AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 937 AM MDT MON APR 7 2008 .UPDATED...ADDED SNOW ADVISORY FOR THE WEST ELK AND SAWATCH MOUNTAINS AND THE GRAND MESA. && .SHORT TERM...TODAY THROUGH TUESDAY NIGHT... THE RUC SEEMS TO HAVE THIS MORNINGS PRECIP COVERED. IT HAS THE COLD FRONT WELL POSITIONED...BETWEEN PUC AND CNY AND EXTENDED ENE THROUGH NW CO. IT ALL PAINTS PRECIP OVER THE NORTHERN HALF OF THE FORECAST AREA WITH ENHANCED OROGRAPHIC SNOW OVER THE SAN JUANS. AS THE FRONT MOVES ESE THROUGH THE DAY...WINDS WILL SHIFT TO NW AND N AND COLD ADVECTION WILL KEEP THE SNOW GOING IN THE MOUNTAINS AND HIGH VALLEYS. THE FRONT SHOULD BE SOUTH AND EAST OF THE FORECAST AREA BY SUNSET... THOUGH GFS AND NAM BOTH HINT AT THE POSSIBILITY THE FRONT MAY HANG UP OVER THE SAN JUAN MTS AND JUST WASH OUT THERE. WILL CONTINUE THE SNOW ADVYS THRU TODAY. ONLY SIGNIFICANT CHANGE TO THE FORECAST WILL BE TO DECREASE CLOUD COVER AND PRECIP OVER THE LOWER ELEVATIONS OF THE FOUR CORNERS THIS MORNING. GFS AND NAM BOTH ADVECT DRIER AIR INTO THE AREA LATER TONIGHT AND TUE MORNING. THEN AS NEXT STRONGER TROUGH AND COLD FRONT DEVELOP OVER THE WESTERN GREAT BASIN...HIGH AND MID CLOUDS WILL INCREASE TUE AFTERNOON AND TUE NIGHT. KEPT TEMPS NEARER TO THE WARMER GFS GUIDANCE AS THIS HAS BEEN THE TREND THE LAST FEW DAYS...WITH THE NAM TEMP BEING TOO COOL. .LONG TERM...WEDNESDAY THROUGH SUNDAY... MODELS HAVE COME TOGETHER OVER THE LAST COUPLE OF RUNS IN THE HANDLING OF THE TROUGH SCHEDULED FOR WED/THU. THE ECMWF HAS TRENDED MORE NORTHERLY WITH LESS OF A SPLIT...AND THE GFS IS A JUST A TAD MORE SOUTHERLY. THEREFORE OUR FORECAST AREA REMAINS IN POSITION TO SEE A GOOD PRECIPITATION EVENT WITH WIDESPREAD SHOWERS DEVELOPING ON WED. THE DAY BEGINS UNDER SOUTHWEST FLOW/WARM ADVECTION AHEAD OF A SURFACE FRONT AND UPPER TROUGH THAT WILL MOVE WEST TO EAST ACROSS THE AREA LATER IN THE AFTERNOON. THE EARLY REGIME WILL FAVOR SOUTHWEST FACING SLOPES...WITH PRECIPITATION BECOMING MORE WIDESPREAD NEAR THE FRONT. THE TROUGH AXIS LOOKS LIKE IT IS TIMED TO BE OVER FAR WESTERN CO AT AROUND 00Z THU...WITH THE EC NOW JUST A LITTLE BEHIND THE GFS. IN ANY CASE INSTABILITY WILL INCREASE THROUGH THE DAY AND CONTINUE THROUGH THE NIGHT. SNOW LEVELS WILL LOWER FROM 8KFT IN THE AFTERNOON TO 5500-6000FT BY THURSDAY MORNING. BY MIDNIGHT WED THE LEFT EXIT REGION OF THE JET WILL RESULT IN A BROAD AREA OF DIFLUENCE OVER EASTERN UT WHICH WILL THEN SHIFT EAST BY EARLY THU MORNING. THEN THE UPPER JET WILL SWEEP ACROSS THE AREA DURING THE DAY THURSDAY. THIS UPPER SUPPORT...ALONG WITH INSTABILITY AS THE COLD CORE ALOFT MOVES OVERHEAD WILL KEEP MOUNTAIN SNOW GOING...ESPECIALLY FOR FAVORED NORTHWEST FACING SLOPES. THE FAR WEST WILL SEE ACTIVITY DIMINISH BEGINNING EARLY IN THE DAY...WITH DRYING MOVING FROM WEST TO EAST THROUGH THE AFTERNOON AND EVENING BEHIND THE TROUGH. THE SNOW LEVEL WILL REMAIN AROUND 6500-7000FT THROUGH THE DAY...THEN LOWER OVERNIGHT. FRIDAY: SEASONABLY COLD NW FLOW CONTINUES WITH POTENTIAL LIGHT SNOWFALL IN THE NORTHERN MTNS. SATURDAY-SUNDAY: DRY AND WARM AS A PROGRESSIVE RIDGE BUILDS OVERHEAD BY SUNDAY. NUDGED TEMPS UPWARD A BIT BUT MAY STILL NEED TO BE WARMED. LOOKS LIKE A BEAUTIFUL SPRING WEEKEND. && .AVIATION... WIDESPREAD MVFR...AND AREAS OF IFR...CIGS AND VSBYS WILL CONTINUE ACROSS THE NORTHERN AND CENTRAL MOUNTAINS OF COLORADO AND UTAH AS ANOTHER LATE WINTER STORMS MOVES THROUGH THE AREA. ISOLATED HEAVIER SNOW SHOWERS WILL PRODUCE LOCAL LIFR CIGS AND VSBYS. SIMILAR CONDITIONS...THOUGH MORE LOCALIZED...WITH CONTINUE OVER THE SOUTHWEST CO MTS TODAY. CONDITIONS WILL GRADUALLY IMPROVE TONIGHT. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...SNOW ADVISORY IN EFFECT FOR THE NORTHERN AND CENTRAL MOUNTAINS AND PLATEAUS THROUGH 6 PM THIS EVENING...ZONES 2/3/4/5/9/10/ 12 AND 13. .UT...SNOW ADVISORY IN EFFECT FOR THE TAVAPUTS PLATEAU AND EASTERN UINTA MOUNTAINS THROUGH 6 PM THIS EVENING...ZONES 25 AND 23. $$ SHORT TERM...CJC/NL LONG TERM....EH AVIATION.....CJC co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 928 AM MDT MON APR 7 2008 .UPDATED...ADDED SNOW ADVISORY FOR THE WEST ELK AND SAWATCH MOUNTAINS. && .SHORT TERM...TODAY THROUGH TUESDAY NIGHT... THE RUC SEEMS TO HAVE THIS MORNINGS PRECIP COVERED. IT HAS THE COLD FRONT WELL POSITIONED...BETWEEN PUC AND CNY AND EXTENDED ENE THROUGH NW CO. IT ALL PAINTS PRECIP OVER THE NORTHERN HALF OF THE FORECAST AREA WITH ENHANCED OROGRAPHIC SNOW OVER THE SAN JUANS. AS THE FRONT MOVES ESE THROUGH THE DAY...WINDS WILL SHIFT TO NW AND N AND COLD ADVECTION WILL KEEP THE SNOW GOING IN THE MOUNTAINS AND HIGH VALLEYS. THE FRONT SHOULD BE SOUTH AND EAST OF THE FORECAST AREA BY SUNSET... THOUGH GFS AND NAM BOTH HINT AT THE POSSIBILITY THE FRONT MAY HANG UP OVER THE SAN JUAN MTS AND JUST WASH OUT THERE. WILL CONTINUE THE SNOW ADVYS THRU TODAY. ONLY SIGNIFICANT CHANGE TO THE FORECAST WILL BE TO DECREASE CLOUD COVER AND PRECIP OVER THE LOWER ELEVATIONS OF THE FOUR CORNERS THIS MORNING. GFS AND NAM BOTH ADVECT DRIER AIR INTO THE AREA LATER TONIGHT AND TUE MORNING. THEN AS NEXT STRONGER TROUGH AND COLD FRONT DEVELOP OVER THE WESTERN GREAT BASIN...HIGH AND MID CLOUDS WILL INCREASE TUE AFTERNOON AND TUE NIGHT. KEPT TEMPS NEARER TO THE WARMER GFS GUIDANCE AS THIS HAS BEEN THE TREND THE LAST FEW DAYS...WITH THE NAM TEMP BEING TOO COOL. .LONG TERM...WEDNESDAY THROUGH SUNDAY... MODELS HAVE COME TOGETHER OVER THE LAST COUPLE OF RUNS IN THE HANDLING OF THE TROUGH SCHEDULED FOR WED/THU. THE ECMWF HAS TRENDED MORE NORTHERLY WITH LESS OF A SPLIT...AND THE GFS IS A JUST A TAD MORE SOUTHERLY. THEREFORE OUR FORECAST AREA REMAINS IN POSITION TO SEE A GOOD PRECIPITATION EVENT WITH WIDESPREAD SHOWERS DEVELOPING ON WED. THE DAY BEGINS UNDER SOUTHWEST FLOW/WARM ADVECTION AHEAD OF A SURFACE FRONT AND UPPER TROUGH THAT WILL MOVE WEST TO EAST ACROSS THE AREA LATER IN THE AFTERNOON. THE EARLY REGIME WILL FAVOR SOUTHWEST FACING SLOPES...WITH PRECIPITATION BECOMING MORE WIDESPREAD NEAR THE FRONT. THE TROUGH AXIS LOOKS LIKE IT IS TIMED TO BE OVER FAR WESTERN CO AT AROUND 00Z THU...WITH THE EC NOW JUST A LITTLE BEHIND THE GFS. IN ANY CASE INSTABILITY WILL INCREASE THROUGH THE DAY AND CONTINUE THROUGH THE NIGHT. SNOW LEVELS WILL LOWER FROM 8KFT IN THE AFTERNOON TO 5500-6000FT BY THURSDAY MORNING. BY MIDNIGHT WED THE LEFT EXIT REGION OF THE JET WILL RESULT IN A BROAD AREA OF DIFLUENCE OVER EASTERN UT WHICH WILL THEN SHIFT EAST BY EARLY THU MORNING. THEN THE UPPER JET WILL SWEEP ACROSS THE AREA DURING THE DAY THURSDAY. THIS UPPER SUPPORT...ALONG WITH INSTABILITY AS THE COLD CORE ALOFT MOVES OVERHEAD WILL KEEP MOUNTAIN SNOW GOING...ESPECIALLY FOR FAVORED NORTHWEST FACING SLOPES. THE FAR WEST WILL SEE ACTIVITY DIMINISH BEGINNING EARLY IN THE DAY...WITH DRYING MOVING FROM WEST TO EAST THROUGH THE AFTERNOON AND EVENING BEHIND THE TROUGH. THE SNOW LEVEL WILL REMAIN AROUND 6500-7000FT THROUGH THE DAY...THEN LOWER OVERNIGHT. FRIDAY: SEASONABLY COLD NW FLOW CONTINUES WITH POTENTIAL LIGHT SNOWFALL IN THE NORTHERN MTNS. SATURDAY-SUNDAY: DRY AND WARM AS A PROGRESSIVE RIDGE BUILDS OVERHEAD BY SUNDAY. NUDGED TEMPS UPWARD A BIT BUT MAY STILL NEED TO BE WARMED. LOOKS LIKE A BEAUTIFUL SPRING WEEKEND. && .AVIATION... WIDESPREAD MVFR...AND AREAS OF IFR...CIGS AND VSBYS WILL CONTINUE ACROSS THE NORTHERN AND CENTRAL MOUNTAINS OF COLORADO AND UTAH AS ANOTHER LATE WINTER STORMS MOVES THROUGH THE AREA. ISOLATED HEAVIER SNOW SHOWERS WILL PRODUCE LOCAL LIFR CIGS AND VSBYS. SIMILAR CONDITIONS...THOUGH MORE LOCALIZED...WITH CONTINUE OVER THE SOUTHWEST CO MTS TODAY. CONDITIONS WILL GRADUALLY IMPROVE TONIGHT. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...SNOW ADVISORY IN EFFECT FOR THE NORTHERN AND CENTRAL MOUNTAINS AND PLATEAUS THROUGH 6 PM THIS EVENING...ZONES 2/3/4/5/10/ 12 AND 13. .UT...SNOW ADVISORY IN EFFECT FOR THE TAVAPUTS PLATEAU AND EASTERN UINTA MOUNTAINS THROUGH 6 PM THIS EVENING...ZONES 25 AND 23. $$ SHORT TERM...CJC/NL LONG TERM....EH AVIATION.....CJC co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 827 AM MDT MON APR 7 2008 .UPDATED...ADDED HEAVY SNOW WARNING FOR THE CENTRAL YAMPA RIVER BASIN SOUTH OF CRAIG. && .SHORT TERM...TODAY THROUGH TUESDAY NIGHT... THE RUC SEEMS TO HAVE THIS MORNINGS PRECIP COVERED. IT HAS THE COLD FRONT WELL POSITIONED...BETWEEN PUC AND CNY AND EXTENDED ENE THROUGH NW CO. IT ALL PAINTS PRECIP OVER THE NORTHERN HALF OF THE FORECAST AREA WITH ENHANCED OROGRAPHIC SNOW OVER THE SAN JUANS. AS THE FRONT MOVES ESE THROUGH THE DAY...WINDS WILL SHIFT TO NW AND N AND COLD ADVECTION WILL KEEP THE SNOW GOING IN THE MOUNTAINS AND HIGH VALLEYS. THE FRONT SHOULD BE SOUTH AND EAST OF THE FORECAST AREA BY SUNSET... THOUGH GFS AND NAM BOTH HINT AT THE POSSIBILITY THE FRONT MAY HANG UP OVER THE SAN JUAN MTS AND JUST WASH OUT THERE. WILL CONTINUE THE SNOW ADVYS THRU TODAY. ONLY SIGNIFICANT CHANGE TO THE FORECAST WILL BE TO DECREASE CLOUD COVER AND PRECIP OVER THE LOWER ELEVATIONS OF THE FOUR CORNERS THIS MORNING. GFS AND NAM BOTH ADVECT DRIER AIR INTO THE AREA LATER TONIGHT AND TUE MORNING. THEN AS NEXT STRONGER TROUGH AND COLD FRONT DEVELOP OVER THE WESTERN GREAT BASIN...HIGH AND MID CLOUDS WILL INCREASE TUE AFTERNOON AND TUE NIGHT. KEPT TEMPS NEARER TO THE WARMER GFS GUIDANCE AS THIS HAS BEEN THE TREND THE LAST FEW DAYS...WITH THE NAM TEMP BEING TOO COOL. .LONG TERM...WEDNESDAY THROUGH SUNDAY... MODELS HAVE COME TOGETHER OVER THE LAST COUPLE OF RUNS IN THE HANDLING OF THE TROUGH SCHEDULED FOR WED/THU. THE ECMWF HAS TRENDED MORE NORTHERLY WITH LESS OF A SPLIT...AND THE GFS IS A JUST A TAD MORE SOUTHERLY. THEREFORE OUR FORECAST AREA REMAINS IN POSITION TO SEE A GOOD PRECIPITATION EVENT WITH WIDESPREAD SHOWERS DEVELOPING ON WED. THE DAY BEGINS UNDER SOUTHWEST FLOW/WARM ADVECTION AHEAD OF A SURFACE FRONT AND UPPER TROUGH THAT WILL MOVE WEST TO EAST ACROSS THE AREA LATER IN THE AFTERNOON. THE EARLY REGIME WILL FAVOR SOUTHWEST FACING SLOPES...WITH PRECIPITATION BECOMING MORE WIDESPREAD NEAR THE FRONT. THE TROUGH AXIS LOOKS LIKE IT IS TIMED TO BE OVER FAR WESTERN CO AT AROUND 00Z THU...WITH THE EC NOW JUST A LITTLE BEHIND THE GFS. IN ANY CASE INSTABILITY WILL INCREASE THROUGH THE DAY AND CONTINUE THROUGH THE NIGHT. SNOW LEVELS WILL LOWER FROM 8KFT IN THE AFTERNOON TO 5500-6000FT BY THURSDAY MORNING. BY MIDNIGHT WED THE LEFT EXIT REGION OF THE JET WILL RESULT IN A BROAD AREA OF DIFLUENCE OVER EASTERN UT WHICH WILL THEN SHIFT EAST BY EARLY THU MORNING. THEN THE UPPER JET WILL SWEEP ACROSS THE AREA DURING THE DAY THURSDAY. THIS UPPER SUPPORT...ALONG WITH INSTABILITY AS THE COLD CORE ALOFT MOVES OVERHEAD WILL KEEP MOUNTAIN SNOW GOING...ESPECIALLY FOR FAVORED NORTHWEST FACING SLOPES. THE FAR WEST WILL SEE ACTIVITY DIMINISH BEGINNING EARLY IN THE DAY...WITH DRYING MOVING FROM WEST TO EAST THROUGH THE AFTERNOON AND EVENING BEHIND THE TROUGH. THE SNOW LEVEL WILL REMAIN AROUND 6500-7000FT THROUGH THE DAY...THEN LOWER OVERNIGHT. FRIDAY: SEASONABLY COLD NW FLOW CONTINUES WITH POTENTIAL LIGHT SNOWFALL IN THE NORTHERN MTNS. SATURDAY-SUNDAY: DRY AND WARM AS A PROGRESSIVE RIDGE BUILDS OVERHEAD BY SUNDAY. NUDGED TEMPS UPWARD A BIT BUT MAY STILL NEED TO BE WARMED. LOOKS LIKE A BEAUTIFUL SPRING WEEKEND. && .AVIATION... WIDESPREAD MVFR...AND AREAS OF IFR...CIGS AND VSBYS WILL CONTINUE ACROSS THE NORTHERN AND CENTRAL MOUNTAINS OF COLORADO AND UTAH AS ANOTHER LATE WINTER STORMS MOVES THROUGH THE AREA. ISOLATED HEAVIER SNOW SHOWERS WILL PRODUCE LOCAL LIFR CIGS AND VSBYS. SIMILAR CONDITIONS...THOUGH MORE LOCALIZED...WITH CONTINUE OVER THE SOUTHWEST CO MTS TODAY. CONDITIONS WILL GRADUALLY IMPROVE TONIGHT. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...SNOW ADVISORY IN EFFECT FOR THE NORTHERN MOUNTAINS AND PLATEAUS THROUGH 6 PM THIS EVENING...ZONES 2/3/4/5/10/13. .UT...SNOW ADVISORY IN EFFECT FOR THE TAVAPUTS PLATEAU AND EASTERN UINTA MOUNTAINS THROUGH 6 PM THIS EVENING...ZONES 25 AND 23. $$ SHORT TERM...CJC/NL LONG TERM....EH AVIATION.....CJC co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 755 AM MDT MON APR 7 2008 .UPDATED...ADDED SNOW ADVISORY TO THE STEAMBOAT SPRINGS AREA. && .SHORT TERM...TODAY THROUGH TUESDAY NIGHT... THE RUC SEEMS TO HAVE THIS MORNINGS PRECIP COVERED. IT HAS THE COLD FRONT WELL POSITIONED...BETWEEN PUC AND CNY AND EXTENDED ENE THROUGH NW CO. IT ALL PAINTS PRECIP OVER THE NORTHERN HALF OF THE FORECAST AREA WITH ENHANCED OROGRAPHIC SNOW OVER THE SAN JUANS. AS THE FRONT MOVES ESE THROUGH THE DAY...WINDS WILL SHIFT TO NW AND N AND COLD ADVECTION WILL KEEP THE SNOW GOING IN THE MOUNTAINS AND HIGH VALLEYS. THE FRONT SHOULD BE SOUTH AND EAST OF THE FORECAST AREA BY SUNSET... THOUGH GFS AND NAM BOTH HINT AT THE POSSIBILITY THE FRONT MAY HANG UP OVER THE SAN JUAN MTS AND JUST WASH OUT THERE. WILL CONTINUE THE SNOW ADVYS THRU TODAY. ONLY SIGNIFICANT CHANGE TO THE FORECAST WILL BE TO DECREASE CLOUD COVER AND PRECIP OVER THE LOWER ELEVATIONS OF THE FOUR CORNERS THIS MORNING. GFS AND NAM BOTH ADVECT DRIER AIR INTO THE AREA LATER TONIGHT AND TUE MORNING. THEN AS NEXT STRONGER TROUGH AND COLD FRONT DEVELOP OVER THE WESTERN GREAT BASIN...HIGH AND MID CLOUDS WILL INCREASE TUE AFTERNOON AND TUE NIGHT. KEPT TEMPS NEARER TO THE WARMER GFS GUIDANCE AS THIS HAS BEEN THE TREND THE LAST FEW DAYS...WITH THE NAM TEMP BEING TOO COOL. .LONG TERM...WEDNESDAY THROUGH SUNDAY... MODELS HAVE COME TOGETHER OVER THE LAST COUPLE OF RUNS IN THE HANDLING OF THE TROUGH SCHEDULED FOR WED/THU. THE ECMWF HAS TRENDED MORE NORTHERLY WITH LESS OF A SPLIT...AND THE GFS IS A JUST A TAD MORE SOUTHERLY. THEREFORE OUR FORECAST AREA REMAINS IN POSITION TO SEE A GOOD PRECIPITATION EVENT WITH WIDESPREAD SHOWERS DEVELOPING ON WED. THE DAY BEGINS UNDER SOUTHWEST FLOW/WARM ADVECTION AHEAD OF A SURFACE FRONT AND UPPER TROUGH THAT WILL MOVE WEST TO EAST ACROSS THE AREA LATER IN THE AFTERNOON. THE EARLY REGIME WILL FAVOR SOUTHWEST FACING SLOPES...WITH PRECIPITATION BECOMING MORE WIDESPREAD NEAR THE FRONT. THE TROUGH AXIS LOOKS LIKE IT IS TIMED TO BE OVER FAR WESTERN CO AT AROUND 00Z THU...WITH THE EC NOW JUST A LITTLE BEHIND THE GFS. IN ANY CASE INSTABILITY WILL INCREASE THROUGH THE DAY AND CONTINUE THROUGH THE NIGHT. SNOW LEVELS WILL LOWER FROM 8KFT IN THE AFTERNOON TO 5500-6000FT BY THURSDAY MORNING. BY MIDNIGHT WED THE LEFT EXIT REGION OF THE JET WILL RESULT IN A BROAD AREA OF DIFLUENCE OVER EASTERN UT WHICH WILL THEN SHIFT EAST BY EARLY THU MORNING. THEN THE UPPER JET WILL SWEEP ACROSS THE AREA DURING THE DAY THURSDAY. THIS UPPER SUPPORT...ALONG WITH INSTABILITY AS THE COLD CORE ALOFT MOVES OVERHEAD WILL KEEP MOUNTAIN SNOW GOING...ESPECIALLY FOR FAVORED NORTHWEST FACING SLOPES. THE FAR WEST WILL SEE ACTIVITY DIMINISH BEGINNING EARLY IN THE DAY...WITH DRYING MOVING FROM WEST TO EAST THROUGH THE AFTERNOON AND EVENING BEHIND THE TROUGH. THE SNOW LEVEL WILL REMAIN AROUND 6500-7000FT THROUGH THE DAY...THEN LOWER OVERNIGHT. FRIDAY: SEASONABLY COLD NW FLOW CONTINUES WITH POTENTIAL LIGHT SNOWFALL IN THE NORTHERN MTNS. SATURDAY-SUNDAY: DRY AND WARM AS A PROGRESSIVE RIDGE BUILDS OVERHEAD BY SUNDAY. NUDGED TEMPS UPWARD A BIT BUT MAY STILL NEED TO BE WARMED. LOOKS LIKE A BEAUTIFUL SPRING WEEKEND. && .AVIATION... WIDESPREAD MVFR...AND AREAS OF IFR...CIGS AND VSBYS WILL CONTINUE ACROSS THE NORTHERN AND CENTRAL MOUNTAINS OF COLORADO AND UTAH AS ANOTHER LATE WINTER STORMS MOVES THROUGH THE AREA. ISOLATED HEAVIER SNOW SHOWERS WILL PRODUCE LOCAL LIFR CIGS AND VSBYS. SIMILAR CONDITIONS...THOUGH MORE LOCALIZED...WITH CONTINUE OVER THE SOUTHWEST CO MTS TODAY. CONDITIONS WILL GRADUALLY IMPROVE TONIGHT. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...SNOW ADVISORY IN EFFECT FOR THE NORTHERN MOUNTAINS AND PLATEAUS THROUGH 6 PM THIS EVENING...ZONES 3/4/5/10/13. .UT...SNOW ADVISORY IN EFFECT FOR THE TAVAPUTS PLATEAU AND EASTERN UINTA MOUNTAINS THROUGH 6 PM THIS EVENING...ZONES 25 AND 23. $$ SHORT TERM...CJC/NL LONG TERM....EH AVIATION.....CJC co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 311 AM MDT MON APR 7 2008 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT... THE RUC SEEMS TO HAVE THIS MORNINGS PRECIP COVERED. IT HAS THE COLD FRONT WELL POSITIONED...BETWEEN PUC AND CNY AND EXTENDED ENE THROUGH NW CO. IT ALL PAINTS PRECIP OVER THE NORTHERN HALF OF THE FORECAST AREA WITH ENHANCED OROGRAPHIC SNOW OVER THE SAN JUANS. AS THE FRONT MOVES ESE THROUGH THE DAY...WINDS WILL SHIFT TO NW AND N AND COLD ADVECTION WILL KEEP THE SNOW GOING IN THE MOUNTAINS AND HIGH VALLEYS. THE FRONT SHOULD BE SOUTH AND EAST OF THE FORECAST AREA BY SUNSET... THOUGH GFS AND NAM BOTH HINT AT THE POSSIBILITY THE FRONT MAY HANG UP OVER THE SAN JUAN MTS AND JUST WASH OUT THERE. WILL CONTINUE THE SNOW ADVYS THRU TODAY. ONLY SIGNIFICANT CHANGE TO THE FORECAST WILL BE TO DECREASE CLOUD COVER AND PRECIP OVER THE LOWER ELEVATIONS OF THE FOUR CORNERS THIS MORNING. GFS AND NAM BOTH ADVECT DRIER AIR INTO THE AREA LATER TONIGHT AND TUE MORNING. THEN AS NEXT STRONGER TROUGH AND COLD FRONT DEVELOP OVER THE WESTERN GREAT BASIN...HIGH AND MID CLOUDS WILL INCREASE TUE AFTERNOON AND TUE NIGHT. KEPT TEMPS NEARER TO THE WARMER GFS GUIDANCE AS THIS HAS BEEN THE TREND THE LAST FEW DAYS...WITH THE NAM TEMP BEING TOO COOL. .LONG TERM...WEDNESDAY THROUGH SUNDAY... MODELS HAVE COME TOGETHER OVER THE LAST COUPLE OF RUNS IN THE HANDLING OF THE TROUGH SCHEDULED FOR WED/THU. THE ECMWF HAS TRENDED MORE NORTHERLY WITH LESS OF A SPLIT...AND THE GFS IS A JUST A TAD MORE SOUTHERLY. THEREFORE OUR FORECAST AREA REMAINS IN POSITION TO SEE A GOOD PRECIPITATION EVENT WITH WIDESPREAD SHOWERS DEVELOPING ON WED. THE DAY BEGINS UNDER SOUTHWEST FLOW/WARM ADVECTION AHEAD OF A SURFACE FRONT AND UPPER TROUGH THAT WILL MOVE WEST TO EAST ACROSS THE AREA LATER IN THE AFTERNOON. THE EARLY REGIME WILL FAVOR SOUTHWEST FACING SLOPES...WITH PRECIPITATION BECOMING MORE WIDESPREAD NEAR THE FRONT. THE TROUGH AXIS LOOKS LIKE IT IS TIMED TO BE OVER FAR WESTERN CO AT AROUND 00Z THU...WITH THE EC NOW JUST A LITTLE BEHIND THE GFS. IN ANY CASE INSTABILITY WILL INCREASE THROUGH THE DAY AND CONTINUE THROUGH THE NIGHT. SNOW LEVELS WILL LOWER FROM 8KFT IN THE AFTERNOON TO 5500-6000FT BY THURSDAY MORNING. BY MIDNIGHT WED THE LEFT EXIT REGION OF THE JET WILL RESULT IN A BROAD AREA OF DIFLUENCE OVER EASTERN UT WHICH WILL THEN SHIFT EAST BY EARLY THU MORNING. THEN THE UPPER JET WILL SWEEP ACROSS THE AREA DURING THE DAY THURSDAY. THIS UPPER SUPPORT...ALONG WITH INSTABILITY AS THE COLD CORE ALOFT MOVES OVERHEAD WILL KEEP MOUNTAIN SNOW GOING...ESPECIALLY FOR FAVORED NORTHWEST FACING SLOPES. THE FAR WEST WILL SEE ACTIVITY DIMINISH BEGINNING EARLY IN THE DAY...WITH DRYING MOVING FROM WEST TO EAST THROUGH THE AFTERNOON AND EVENING BEHIND THE TROUGH. THE SNOW LEVEL WILL REMAIN AROUND 6500-7000FT THROUGH THE DAY...THEN LOWER OVERNIGHT. FRIDAY: SEASONABLY COLD NW FLOW CONTINUES WITH POTENTIAL LIGHT SNOWFALL IN THE NORTHERN MTNS. SATURDAY-SUNDAY: DRY AND WARM AS A PROGRESSIVE RIDGE BUILDS OVERHEAD BY SUNDAY. NUDGED TEMPS UPWARD A BIT BUT MAY STILL NEED TO BE WARMED. LOOKS LIKE A BEAUTIFUL SPRING WEEKEND. && .AVIATION... WIDESPREAD MVFR...AND AREAS OF IFR...CIGS AND VSBYS WILL CONTINUE ACROSS THE NORTHERN AND CENTRAL MOUNTAINS OF COLORADO AND UTAH AS ANOTHER LATE WINTER STORMS MOVES THROUGH THE AREA. ISOLATED HEAVIER SNOW SHOWERS WILL PRODUCE LOCAL LIFR CIGS AND VSBYS. SIMILAR CONDITIONS...THOUGH MORE LOCALIZED...WITH CONTINUE OVER THE SOUTHWEST CO MTS TODAY. CONDITIONS WILL GRADUALLY IMPROVE TONIGHT. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...SNOW ADVISORY IN EFFECT FOR THE NORTHERN MOUNTAINS AND PLATEAUS FROM 9 PM MDT THROUGH 6 PM THIS EVENING...ZONES 3/4/10/13. .UT...SNOW ADVISORY IN EFFECT FOR THE TAVAPUTS PLATEAU AND EASTERN UINTA MOUNTAINS THROUGH 6 PM THIS EVENING...ZONES 25 AND 23. $$ SHORT TERM...CJC LONG TERM....EH AVIATION.....CJC co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 230 PM MDT SUN APR 6 2008 .SHORT TERM...FOR TONIGHT...MOISTURE WILL BE INCREASING OVER WESTERN COLORADO AHD OF THE NEXT STORM SYSTEM. THERE WILL BE A SHORT WAVE RIDGE OVER THE CWFA WITH MID LVL WARM AIR ADVECTION PROGGED IN THE MTNS OVERNIGHT. DO NOT ANTICIPATE MUCH SNOWFALL THERE TONIGHT...BUT WILL GO WITH 1-3 INCHES. SWLY WINDS WL FAVOR ZONE 31 FOR HIGHEST AMTS. ACROSS THE NERN PLAINS...WL KEEP SOME ISOLD POPS ALG THE URBAN CORRIDOR BUT DROP THEM FURTHER E THROUGH THIS EVNG. WL SIDE WITH THE DRIER RUC/NAM SOLUTIONS THROUGH 06Z...THEN INTRODUCE PCPN INTO THE GRIDS. CROSS-SECTIONS SHOW INCREASING QG VERTICAL VELOCITIES OVERNIGHT...BUT STRONGEST LIFT ASSOCIATED WITH THE INCOMING TROF WL OCCUR ON MONDAY WHEN COLD AIR ADVECTION DVLPS. ALTHO BOTH THE NAM/GFS SHOW A SIMILAR TRACK WITH THE TROF THE WINDS ARE CONSIDERABLY DIFFERENT IN THE SPATIAL CROSS-SECTIONS. STRONGEST OROGRAPHIC COMPONENT IS REFLECTED IN THE NAM WITH SNOW MDL YIELDING 3-7 INCHES ON MONDAY. COULD BE MORE WITH SOME EMBEDDED CONVECTION. SOUNDINGS IN THE MTNS SHOW CAPES AROUND 200 J/KG MONDAY AFTN SO THREW SOME ISOLD THUNDER IN THE MTNS AS WELL. SOME SORT OF ADVSY MAY BE NEEDED BUT WL HOLD OFF ISSUING ONE AT THIS POINT. ACROSS THE NERN FOOTHILLS AND URBAN CORRIDOR ...LOW LEVEL SELY WINDS WILL FAVOR BDR AND LARIMER COUNTIES SO HEDGED THE HIGHEST POPS FURTHER N. THERE MAY BE A MIX OF RAIN AND SNOW IN THE MRNG BUT INTERACTIVE SOUNDINGS SHOW THE SNOW LEVEL WL BE AROUND 6K FT BY THE AFTN...SO WENT WITH JUST RAIN AT THAT TIME. LITTLE IF ANY SNOW ACCUMULATION EXPECTED IN THE MRNG. ALL MDLS SHOW A DECENT SWATH OF MSTR OVER THE AREA BY MONDAY AFTN SO OPTED FOR LIKELY OR HIGHER POPS IN MOST AREA. SRN SECTIONS OF THE FCST AREA MAY BE DRIER. .LONG TERM...ACTIVE PATTERN STILL SHAPING UP THROUGH THE FIRST HALF OF THE EXTENDED PERIOD. PRECIPITATION WILL BE FALLING OVER PARTS OF THE FORECAST AREA MONDAY EVENING TO START OFF THIS PERIOD. MODELS ARE A LITTLE STRONGER WITH THE WAVE AND THUS A LITTLE SLOWER. THEY SHOW THE WAVE INTENSIFYING INTO A CLOSED LOW OVER WESTERN NEBRASKA AND EASTERN WYOMING LATE MONDAY NIGHT. WILL UP POPS MONDAY NIGHT FOR THIS AND KEEP POPS IN THE FORECAST UNTIL TUESDAY MORNING. A WEAK RIDGE WILL MOVE ACROSS THE STATE TUESDAY AFTERNOON/TUESDAY EVENING. THIS WILL KEEP THINGS DRY. IN THE MEANTIME...A BROAD UPPER LEVEL TROUGH WILL MOVE ONTO THE WEST COAST AND DROP SOUTHEAST INTO THE FOUR CORNERS REGION BY WEDNESDAY MORNING. THE CHANCE FOR PRECIPITATION WITH THE UPPER LEVEL TROUGH WILL BEGIN TUESDAY NIGHT. ONLY SEEING A SLIGHT CHANCE FOR PRECIPITATION TUESDAY NIGHT WITH MOST OF THE MOISTURE AND DYNAMICS REMAINING TO THE WEST. THE CHANCE FOR PRECIPITATION WILL INCREASE WEDNESDAY AND WEDNESDAY NIGHT AS THE TROUGH NEARS...WHICH WILL INCREASE THE MOISTURE AND LIFT OVER THE AREA. MODELS AGREE WITH THE TIMING OFF THE TROUGH AXIS PUSHING THROUGH THE AREA WEDNESDAY NIGHT. THERE ARE DIFFERENCES SHOWING UP WITH THE MODELS THURSDAY ON HOW MUCH THE TROUGH STRENGTHENS ONCE IT EMERGES ONTO THE PLAINS. BECAUSE OF THE DISCREPANCY BETWEEN THE MODELS WILL LEAVE CHANCE POPS IN THE FORECAST. HAVE ADDED SOME LOW POPS TO THE FORECAST FOR FRIDAY WITH THE MODELS INDICATING AN UNSETTLED NORTHWEST FLOW ALOFT IN THE WAKE OF THE UPPER LEVEL TROUGH. ANY PRECIPITATION FRIDAY WILL BE ON THE LIGHT SIDE. AFTER BELOW NORMAL TEMPERATURES FOR MOST OF THE WEEK HIGHS WILL CLIMB TO NEAR NORMAL FOR THE WEEKEND AS AN UPPER LEVEL RIDGE FORMS OVER THE WESTERN U.S. && .AVIATION...VFR CONDITIONS EXPECTED THROUGH TNGT. THERE MAY AGAIN BE SOME WEAK CU BUILDUPS LATE THIS AFTN BUT DO NOT EXPECT THIS TO BE AS BIG AN ISSUE AS YDA. SHUD SEE CHC OF LGT RAIN MIXED WITH SNOW DVLPG TOWARDS 12Z MONDAY BUT NO ACCUMULATION EXPECTED EVEN IN THE GRASSY AREAS. SNOW LEVEL APPEARS TO BE AROUND 6000 FT SO MOST PCPN SHUD BE IN THE FORM OF RAIN ON MONDAY. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. && $$ COOPER/MEIER co AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TALLAHASSEE FL 530 AM EDT MON APR 7 2008 ...UPDATED TO INCLUDE DENSE FOG ADVISORY UNTIL 10 AM EDT/9 AM CDT... .SYNOPSIS... 07Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING THREE AREAS OF DISTURBED WEATHER IN THE UPPER LEVELS ACROSS THE CONUS EARLY THIS MORNING. FAIRLY ACTIVE NORTHERN STREAM WITH CLOSED UPPER LOW/SHORTWAVE PUSHING THROUGH THE UPPER MISSISSIPPI VALLEY TOWARD THE GREAT LAKES AND ANOTHER FAIRLY POTENT SHORTWAVE PUSHING ASHORE ALONG THE PACIFIC NORTHWEST. CLOSER TO HOME WE SEE A WEAK MID LEVEL DISTURBANCE PUSHING OFF THE NORTHEAST FLORIDA COAST. THIS SHORTWAVE WAS RESPONSIBLE FOR SUNDAYS SHOWERS/RAIN ALONG THE COAST/EASTERN FLORIDA BIG BEND. SIGNIFICANT MID/UPPER LEVEL DRYING AND MORE ZONAL FLOW IS QUICKLY BUILDING IN BEHIND THIS SHORTWAVE AND WILL BE WITH US FOR THE BEGINNING OF THE WORK WEEK. AT THE SURFACE...WEAK FRONTAL BOUNDARY STRETCHED FROM NORTHEAST FLORIDA INTO THE NORTHEASTERN GULF OF MEXICO WILL BE SLOWLY BEGINNING TO PUSH SOUTH AND EAST THROUGH THE MORNING HOURS. BEGINNING TO SEE A WEDGE OF HIGH PRESSURE BUILD DOWN INTO THE SOUTHEASTERN STATES WITH FAIRLY RAPID PRESSURE RISES FROM CENTRAL GA NORTHWARD. MID/HIGH LEVEL CLOUDS ASSOCIATED WITH THE DEPARTING SHORTWAVE AREA QUICKLY EXITING EAST AS WELL. BEHIND THE CLOUDS MID-LEVEL DRY AIR OVERTOP THE STILL MOIST BOUNDARY LAYER IS PROMOTING THE DEVELOPMENT OF AREA OF STRATUS AND FOG. THIS STRATUS IS BECOMING WIDESPREAD IN NATURE AND APPEARS MOST AREAS WILL BEGIN THEIR MONDAY WITH MOSTLY CLOUDY TO CLOUDY SKIES. TEMPERATURES GENERALLY IN THE LOWER AND MIDDLE 60S REGIONWIDE. THE FOG IS BECOMING QUITE DENSE IN SPOTS. THE AREAL COVERAGE OF THIS DENSE FOG IS NOW ENOUGH TO REQUIRE A DENSE FOG ADVISORY. WILL EXPECT VISIBILITIES TO LOCALLY FALL TO 1/4MILE OR LESS FOR THE NEXT SEVERAL HOURS MAKING THE MORNING COMMUTE MORE DIFFICULT IN SPOTS. THE DENSE FOG ADVISORY WILL BE IN EFFECT UNTIL 10 AM EDT/9 AM CDT. && .SHORT TERM (MONDAY THROUGH WEDNESDAY NIGHT)... WEDGE OF HIGH PRESSURE CONTINUES TO BUILD SOUTH AND WEST FROM THE CAROLINAS/NORTHERN GA THROUGH THE DAYLIGHT HOURS AS ZONAL FLOW MATERIALIZES ALOFT ALONG THE GULF COAST. GFS/NAM BOTH SHOWING A WEAK SOUTHERN STREAM TROUGH PASSING THROUGH THE CENTRAL/SOUTHERN GOMEX THROUGH THIS EVENING...HOWEVER THIS FEATURE SHOULD REMAIN FAR ENOUGH SOUTH TO HAVE LITTLE/NO IMPACT ON OUR WEATHER. AS THE WEDGE HIGH BUILDS SOUTH...SOMEWHAT DRIER LOWER LEVEL AIR WILL BEGIN TO FILTER IN. WEAK BACKDOOR FRONT/BOUNDARY MOVING SLOWLY SOUTH AND WEST THROUGH THE DAY WILL INTRODUCE THE SURFACE RIDGE. NAME THE MODEL PACKAGE...GFS/NAM/SREF/EC...AND ALL ARE TRYING TO GENERATE A FEW LIGHT SHOWERS/SPRINKLES (MAINLY OVER OUR GA ZONES) WITH THE LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY THIS MORNING/EARLY AFTERNOON. WITH THE LACK OF MID/UPPER LEVEL SUPPORT...THE QPF FIELDS BEING GENERATED CERTAINLY SEEM OVERDONE. HOWEVER...IN RESPECT TO THE NEARLY UNANIMOUS SOLUTIONS WILL ALLOW A VERY SLIGHT 15% POP OVER OUR NORTHERN ZONES WITH A SILENT 10% OR LESS FURTHER SOUTH AND WEST. THIS WILL ALLOW FOR A FEW ISOLATED SHOWERS/SPRINKLES WITHOUT GIVING THE IMPRESSION OF A WET DAY (SINCE IT CERTAINLY WILL NOT BE). IF REGIONAL RADARS SHOW A FEW SHOWERS BEGINNING TO DEVELOP LATE TONIGHT THAN WILL UPDATE TO A SLIGHT 20-25% POP...BUT FEEL THIS IS UNLIKELY AT THIS TIME. ANOTHER FORECAST ISSUE WILL BE THE EXTENT OF LOWER LEVEL CLOUDS OVER OUR NORTHERN/NORTHEASTERN ZONES (MAINLY GA) WHICH IS OFTEN A DIFFICULT FORECAST FIELD WITH THESE WEDGE SURFACE RIDGES. WILL GO ON THE "CONSERVATIVE" SIDE WITH MOSTLY CLOUDY SKIES ACROSS MOST OF OUR GA ZONES AND MOSTLY CLOUDY MORNING SKIES GIVING WAY TO PARTLY CLOUDY SKIES ELSEWHERE. NAM/GFS RH FIELDS ARE NOT PICKING UP ON THE LOWER CLOUD POTENTIAL YET...BUT LOWER/MIDDLE LEVEL MOISTURE IS OFTEN A POORLY FORECAST FIELD BY NUMERICAL GUIDANCE IN THESE SITUATIONS. THE LAST WEDGE THAT BUILT IN EARLIER LAST WEEK RESULTED IN SOME EXTENSIVE AND STUBBORN CLOUDS FROM AROUND KABY TO TIFTON TO JUST NORTH OF VALDOSTA. THESE CLOUDS OFTEN RESULT IN A SIGNIFICANT COOLER DAY THAN WOULD OTHERWISE BE EXPECTED. THIS MAY ONCE AGAIN BECOME THE CASE TODAY INTO TUESDAY. TEMPS SHOULD STILL BE ABLE TO REACH THE UPPER 70S TO AROUND 80 FOR THE SOUTH AND WEST. WILL SHOW A FAIRLY SIGNIFICANT TEMP GRADIENT NORTHEAST OF A LINE FROM AROUND KABY TO KVLD WITH ONLY LOWER 70S FOR OUR FAR NORTHEAST ZONES. IF THE WEDGE REALLY TAKES CONTROL...THEN EVEN THESE TEMPS MAY BE A BIT OVERDONE AND THE TEMP GRADIENT WILL NEED TO BE PUSHED A BIT FURTHER SOUTHWEST. SURFACE HIGH IN FIRM CONTROL OF THE AREA TONIGHT INTO TUESDAY NIGHT. LOOKING FOR A DRY FORECAST WITH RIDGING IN CONTROL THROUGH A DEEP LAYER OF THE TROP. MID LEVEL RIDGE ACTUALLY AMPLIFIES A BIT DURING THE DAY ON TUESDAY. SAME FORECAST PROBLEMS WILL CONTINUE WITH THE POTENTIAL FOR STUBBORN LOW LEVEL STRATUS FOR OUR NORTHEASTERN AREAS. LIKELY WILL SEE ANY LOW STRATUS EXPAND ACROSS A LARGE PORTION OF THE AREA TONIGHT AND THEN BURN OFF DURING TUESDAY MORNING ACROSS NORTHERN FLORIDA/SOUTHEAST ALABAMA. THIS SHOULD SET UP ANOTHER DECENT TEMP GRADIENT WITH NEAR 80 AWAY FROM THE COAST FOR OUR SOUTH/WESTERN ZONES RANGING TO LOWER AND MIDDLE 70S FURTHER NORTH AND EAST. AGAIN TRIED TO ANTICIPATE THE SOUTHERN EXTENT OF ANY LOWER CLOUDS DURING THE AFTERNOON...BUT ONLY TIME WILL TELL. SURFACE RIDGE BEGINS TO WEAKEN AND MOVE EASTWARD WEDNESDAY IN RESPONSE TO THE NEXT COLD FRONT ARRIVING ACROSS THE MISSISSIPPI VALLEY. GRADIENT WILL WEAKEN BRIEFLY AND ALLOW FLOW TO COME AROUND TO THE SOUTHEAST. MOST AREAS WILL ONCE AGAIN SEE A DRY DAY WITH TEMPS WARMING TO AROUND 80 OR A BIT BETTER AWAY FROM THE COAST. THE SOUTHEAST FLOW WILL KEEP COASTAL AREAS IN THE 70S. GFS/SREF SHOWING THE MOISTURE RETURN INTO THE PANHANDLE RESULTING IN A FEW AFTERNOON SHOWERS WEST OF THE APALACHICOLA RIVER. UNDERCUT THE 30-40% POPS ADVERTISED BY MAV/SREF GUIDANCE AS ONCE AGAIN THERE IS LITTLE SUPPORT FROM ABOVE FOR LIFT. GOING WITH A SLIGHT RISK OF A BRIEF SHOWER/TSHOWER OVER THESE WESTERN ZONES...BUT AT THIS POINT WEDNESDAY SHOULD STILL END UP A FAIRLY PLEASANT SPRING DAY. SOUTHEAST GRADIENT TIGHTENS WEDNESDAY NIGHT AS THE SURFACE RIDGE SLIPS OFF THE SOUTHEAST COAST. SURFACE FRONT AND UPPER LEVEL DYNAMICS STILL WELL OFF TO OUR WEST. SO...AFTER ANY EVENING SHOWERS DIMINISH OVER OUR WESTERN ZONES...THE REST OF THE NIGHT SHOULD BE ON THE WARM AND DRY SIDE. && .LONG TERM (THURSDAY THROUGH SUNDAY)... WITH A STRENGTHENING UPPER RIDGE BUILDING NORTHWARD FROM THE NE GULF AND WRN ATLC WEDNESDAY INTO LATE THURSDAY AND SURFACE HIGH ALONG OR JUST OFF NE FL COAST...A GENERALLY WARM AND DRY FCST WILL OPEN THE EXTENDED PERIOD. HIGH MOVES FURTHER OFFSHORE ON THURSDAY AHEAD OF NEXT DEVELOPING SYSTEM. DIGGING SHORTWAVE FINALLY BREAKS DOWN RIDGE BEGINNING FRIDAY WHILE N-S VORTLOBE MOVES ACROSS SE CONUS SAT. AT SURFACE... SHORTWAVE HELPS TO DEFINE LOW WHICH DEVELOPS IN N TX WITH COLD FRONT EXTENDING SWD IN MEX BY 12Z THURS. LOW LIFTS RAPIDLY N/NE TO GREAT LAKES BY 12Z FRI WITH PRE-FRONTAL TROF ACROSS ALA AND PARENT FRONT THRU WRN TENN-ERN ARK...ERN MOST TX. GFS SHOWING PRE-FRONTAL CONVECTION MOVING ACROSS LOCAL AREA FRI AFTERNOON/NIGHT WITH FRONT MOVING ACROSS EARLY SAT. IN ITS WAKE HIGH PRESSURE BUILDS IN WITH DRY NW FLOW THRU AT LEAST SUNDAY EVE OR EARLY MON WHEN ANOTHER WEAK BAND MOISTURE IS POSSIBLE. 12Z ECMWF IS A BIT SLOWER ON THIS FRONTAL TIMING WITH CONVECTION NOT ARRIVING UNTIL FRIDAY NIGHT AND LINGERING INTO A GOOD PORTION OF SATURDAY. FOR CONTINUITY SAKE WILL STAY WITH THE GFS SOLUTION...HOWEVER TIMING OF FRONT MAY NEED TO BE ADJUSTED BACK IN FUTURE FORECAST PACKAGES...ESPECIALLY SINCE LATEST 00Z CANADIAN IS SHOWING STRONG SUPPORT FOR THE SLOWER ECMWF SOLUTION. UNTIL THE FRONT PASSES...TEMPS SHOULD CONTINUE ABOVE CLIMO...WITH INLAND HIGHS LIKELY REACHING THE LOWER TO MID 80S THRU FRI...THEN DROP TO MID-UPPER 70S SAT AND LOW-MID 70S SUNDAY BEFORE RISING UP TO CLIMO AGAIN ON MONDAY. INLAND LOW TEMPS WILL REMAIN ABOVE CLIMO... OR IN LOW 60S THRU SAT THEN IN WAKE OF FRONT DROP MID 40S SUN AND MID-UPPER 40S MON MORNING. && .AVIATION... FOR REST OF THE OVERNIGHT HOURS...AREAS OF FOG/LOW STRATUS ARE EXPECTED ACROSS THE TRI-STATE AREA WITH PLENTY OF SFC MOISTURE PRESENT AND DRIER AIR MOVING IN AT MID LEVELS PER WATER VAPOR IMAGERY. LIFR AND POSSIBLY VLIFR VIS NOT OUT OF THE QUESTION AND ALREADY OCCURRING AT DHN...VLD...TLH...ABY. PFN LIKELY TO ALSO GET THE LOW CEILINGS...BUT THE VSBY NOT ANTICIPATED TO BE QUITE AS LOW. AFT 14-15Z FOG AND LOW CIGS SHOULD SLOWLY LIFT WITH VFR CEILINGS AROUND 4 KFT UNTIL AROUND 20Z. DIFFICULT FORECAST FOR KABY TO KVLD AS LOWER LEVEL STRATUS MAY ATTEMPT TO HOLD ON THROUGH A GOOD PORTION OF THE DAY. ANY LOWER LEVEL (MVFR/IFR) STRATUS FROM KABY TO KVLD IS EXPECTED TO EXPAND SOUTH AND WEST THROUGH MONDAY NIGHT. && .MARINE... WEAK GRADIENT OVER THE FORECAST WATERS AS BOUNDARY CONTINUES TO SLOWLY SLIDE SOUTH AND EAST. HIGH PRESSURE WILL BUILD IN FROM THE NORTHEAST LATER TODAY INTO TONIGHT ALLOWING THE GRADIENT TO TIGHTEN. THIS SURFACE RIDGE WILL REMAIN IN CONTROL THROUGH TUESDAY NIGHT. EXPECT INCREASING FLOW FROM THE EAST TONIGHT AND AGAIN TUESDAY NIGHT WITH ASSOCIATED WITH NOCTURNAL SURGES WHICH ARE COMMON IN THESE SETUPS. WINDS AND SEAS NOW EXPECTED TO REACH CAUTION LEVELS... ESPECIALLY OVER THE OFFSHORE LEGS. FLOW BECOMES MORE SOUTHERLY DURING THE MIDDLE AND END OF THE WORK WEEK AS HIGH PRESSURE SLIDES EAST OFF THE SOUTHEAST COAST AND LOW PRESSURE BEGINS TO TAKE SHAPE WELL TO OUR WEST. && .FIRE WEATHER... ENOUGH LOW LEVEL MOISTURE WILL REMAIN IN PLACE THROUGH THE NEXT SEVERAL DAYS TO RESULT IN RH VALUES STAYING ABOVE CRITICAL LEVELS. RED FLAG CONDITIONS ARE NOT ANTICIPATED THROUGH AT LEAST WEDNESDAY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 81 59 80 59 81 / 10 10 0 0 10 PANAMA CITY 79 62 77 64 77 / 10 10 0 10 20 DOTHAN 80 59 77 60 80 / 10 10 0 10 20 ALBANY 77 57 75 58 80 / 20 10 0 0 10 VALDOSTA 80 57 77 55 82 / 20 10 0 0 10 CROSS CITY 82 57 81 57 82 / 10 10 0 0 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...DENSE FOG ADVISORY IN EFFECT UNTIL 9 AM CDT. GA...DENSE FOG ADVISORY IN EFFECT UNTIL 10 AM EDT. FL...DENSE FOG ADVISORY IN EFFECT UNTIL 10 AM EDT/9 AM CDT. GM...NONE. && $$ AVIATION/FIRE WX...BLOCK PUBLIC/MARINE...MROCZKA LONG TERM...BLOCK/MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 330 AM EDT MON APR 7 2008 .SYNOPSIS... 07Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING THREE AREAS OF DISTURBED WEATHER IN THE UPPER LEVELS ACROSS THE CONUS EARLY THIS MORNING. FAIRLY ACTIVE NORTHERN STREAM WITH CLOSED UPPER LOW/SHORTWAVE PUSHING THROUGH THE UPPER MISSISSIPPI VALLEY TOWARD THE GREAT LAKES AND ANOTHER FAIRLY POTENT SHORTWAVE PUSHING ASHORE ALONG THE PACIFIC NORTHWEST. CLOSER TO HOME WE SEE A WEAK MID LEVEL DISTURBANCE PUSHING OFF THE NORTHEAST FLORIDA COAST. THIS SHORTWAVE WAS RESPONSIBLE FOR SUNDAYS SHOWERS/RAIN ALONG THE COAST/EASTERN FLORIDA BIG BEND. SIGNIFICANT MID/UPPER LEVEL DRYING AND MORE ZONAL FLOW IS QUICKLY BUILDING IN BEHIND THIS SHORTWAVE AND WILL BE WITH US FOR THE BEGINNING OF THE WORK WEEK. AT THE SURFACE...WEAK FRONTAL BOUNDARY STRETCHED FROM NORTHEAST FLORIDA INTO THE NORTHEASTERN GULF OF MEXICO WILL BE SLOWLY BEGINNING TO PUSH SOUTH AND EAST THROUGH THE MORNING HOURS. BEGINNING TO SEE A WEDGE OF HIGH PRESSURE BUILD DOWN INTO THE SOUTHEASTERN STATES WITH FAIRLY RAPID PRESSURE RISES FROM CENTRAL GA NORTHWARD. MID/HIGH LEVEL CLOUDS ASSOCIATED WITH THE DEPARTING SHORTWAVE AREA QUICKLY EXITING EAST AS WELL. BEHIND THE CLOUDS MID-LEVEL DRY AIR OVERTOP THE STILL MOIST BOUNDARY LAYER IS PROMOTING THE DEVELOPMENT OF AREA OF STRATUS AND FOG. THIS STRATUS IS BECOMING WIDESPREAD IN NATURE AND APPEARS MOST AREAS WILL BEGIN THEIR MONDAY WITH MOSTLY CLOUDY TO CLOUDY SKIES. TEMPERATURES GENERALLY IN THE LOWER AND MIDDLE 60S REGIONWIDE. THE FOG IS BECOMING QUITE DENSE IN A FEW AREA...ESPECIALLY FROM KTLH NORTHWARD INTO PORTIONS OF SOUTHERN GEORGIA. MAY REQUIRE A DENSE FOG ADVISORY FOR PORTIONS OF THE AREA IN THE NEXT COUPLE OF HOURS. STAY TUNED. && .SHORT TERM (MONDAY THROUGH WEDNESDAY NIGHT)... WEDGE OF HIGH PRESSURE CONTINUES TO BUILD SOUTH AND WEST FROM THE CAROLINAS/NORTHERN GA THROUGH THE DAYLIGHT HOURS AS ZONAL FLOW MATERIALIZES ALOFT ALONG THE GULF COAST. GFS/NAM BOTH SHOWING A WEAK SOUTHERN STREAM TROUGH PASSING THROUGH THE CENTRAL/SOUTHERN GOMEX THROUGH THIS EVENING...HOWEVER THIS FEATURE SHOULD REMAIN FAR ENOUGH SOUTH TO HAVE LITTLE/NO IMPACT ON OUR WEATHER. AS THE WEDGE HIGH BUILDS SOUTH...SOMEWHAT DRIER LOWER LEVEL AIR WILL BEGIN TO FILTER IN. WEAK BACKDOOR FRONT/BOUNDARY MOVING SLOWLY SOUTH AND WEST THROUGH THE DAY WILL INTRODUCE THE SURFACE RIDGE. NAME THE MODEL PACKAGE...GFS/NAM/SREF/EC...AND ALL ARE TRYING TO GENERATE A FEW LIGHT SHOWERS/SPRINKLES (MAINLY OVER OUR GA ZONES) WITH THE LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY THIS MORNING/EARLY AFTERNOON. WITH THE LACK OF MID/UPPER LEVEL SUPPORT...THE QPF FIELDS BEING GENERATED CERTAINLY SEEM OVERDONE. HOWEVER...IN RESPECT TO THE NEARLY UNANIMOUS SOLUTIONS WILL ALLOW A VERY SLIGHT 15% POP OVER OUR NORTHERN ZONES WITH A SILENT 10% OR LESS FURTHER SOUTH AND WEST. THIS WILL ALLOW FOR A FEW ISOLATED SHOWERS/SPRINKLES WITHOUT GIVING THE IMPRESSION OF A WET DAY (SINCE IT CERTAINLY WILL NOT BE). IF REGIONAL RADARS SHOW A FEW SHOWERS BEGINNING TO DEVELOP LATE TONIGHT THAN WILL UPDATE TO A SLIGHT 20-25% POP...BUT FEEL THIS IS UNLIKELY AT THIS TIME. ANOTHER FORECAST ISSUE WILL BE THE EXTENT OF LOWER LEVEL CLOUDS OVER OUR NORTHERN/NORTHEASTERN ZONES (MAINLY GA) WHICH IS OFTEN A DIFFICULT FORECAST FIELD WITH THESE WEDGE SURFACE RIDGES. WILL GO ON THE "CONSERVATIVE" SIDE WITH MOSTLY CLOUDY SKIES ACROSS MOST OF OUR GA ZONES AND MOSTLY CLOUDY MORNING SKIES GIVING WAY TO PARTLY CLOUDY SKIES ELSEWHERE. NAM/GFS RH FIELDS ARE NOT PICKING UP ON THE LOWER CLOUD POTENTIAL YET...BUT LOWER/MIDDLE LEVEL MOISTURE IS OFTEN A POORLY FORECAST FIELD BY NUMERICAL GUIDANCE IN THESE SITUATIONS. THE LAST WEDGE THAT BUILT IN EARLIER LAST WEEK RESULTED IN SOME EXTENSIVE AND STUBBORN CLOUDS FROM AROUND KABY TO TIFTON TO JUST NORTH OF VALDOSTA. THESE CLOUDS OFTEN RESULT IN A SIGNIFICANT COOLER DAY THAN WOULD OTHERWISE BE EXPECTED. THIS MAY ONCE AGAIN BECOME THE CASE TODAY INTO TUESDAY. TEMPS SHOULD STILL BE ABLE TO REACH THE UPPER 70S TO AROUND 80 FOR THE SOUTH AND WEST. WILL SHOW A FAIRLY SIGNIFICANT TEMP GRADIENT NORTHEAST OF A LINE FROM AROUND KABY TO KVLD WITH ONLY LOWER 70S FOR OUR FAR NORTHEAST ZONES. IF THE WEDGE REALLY TAKES CONTROL...THEN EVEN THESE TEMPS MAY BE A BIT OVERDONE AND THE TEMP GRADIENT WILL NEED TO BE PUSHED A BIT FURTHER SOUTHWEST. SURFACE HIGH IN FIRM CONTROL OF THE AREA TONIGHT INTO TUESDAY NIGHT. LOOKING FOR A DRY FORECAST WITH RIDGING IN CONTROL THROUGH A DEEP LAYER OF THE TROP. MID LEVEL RIDGE ACTUALLY AMPLIFIES A BIT DURING THE DAY ON TUESDAY. SAME FORECAST PROBLEMS WILL CONTINUE WITH THE POTENTIAL FOR STUBBORN LOW LEVEL STRATUS FOR OUR NORTHEASTERN AREAS. LIKELY WILL SEE ANY LOW STRATUS EXPAND ACROSS A LARGE PORTION OF THE AREA TONIGHT AND THEN BURN OFF DURING TUESDAY MORNING ACROSS NORTHERN FLORIDA/SOUTHEAST ALABAMA. THIS SHOULD SET UP ANOTHER DECENT TEMP GRADIENT WITH NEAR 80 AWAY FROM THE COAST FOR OUR SOUTH/WESTERN ZONES RANGING TO LOWER AND MIDDLE 70S FURTHER NORTH AND EAST. AGAIN TRIED TO ANTICIPATE THE SOUTHERN EXTENT OF ANY LOWER CLOUDS DURING THE AFTERNOON...BUT ONLY TIME WILL TELL. SURFACE RIDGE BEGINS TO WEAKEN AND MOVE EASTWARD WEDNESDAY IN RESPONSE TO THE NEXT COLD FRONT ARRIVING ACROSS THE MISSISSIPPI VALLEY. GRADIENT WILL WEAKEN BRIEFLY AND ALLOW FLOW TO COME AROUND TO THE SOUTHEAST. MOST AREAS WILL ONCE AGAIN SEE A DRY DAY WITH TEMPS WARMING TO AROUND 80 OR A BIT BETTER AWAY FROM THE COAST. THE SOUTHEAST FLOW WILL KEEP COASTAL AREAS IN THE 70S. GFS/SREF SHOWING THE MOISTURE RETURN INTO THE PANHANDLE RESULTING IN A FEW AFTERNOON SHOWERS WEST OF THE APALACHICOLA RIVER. UNDERCUT THE 30-40% POPS ADVERTISED BY MAV/SREF GUIDANCE AS ONCE AGAIN THERE IS LITTLE SUPPORT FROM ABOVE FOR LIFT. GOING WITH A SLIGHT RISK OF A BRIEF SHOWER/TSHOWER OVER THESE WESTERN ZONES...BUT AT THIS POINT WEDNESDAY SHOULD STILL END UP A FAIRLY PLEASANT SPRING DAY. SOUTHEAST GRADIENT TIGHTENS WEDNESDAY NIGHT AS THE SURFACE RIDGE SLIPS OFF THE SOUTHEAST COAST. SURFACE FRONT AND UPPER LEVEL DYNAMICS STILL WELL OFF TO OUR WEST. SO...AFTER ANY EVENING SHOWERS DIMINISH OVER OUR WESTERN ZONES...THE REST OF THE NIGHT SHOULD BE ON THE WARM AND DRY SIDE. && .LONG TERM (THURSDAY THROUGH SUNDAY)... WITH A STRENGTHENING UPPER RIDGE BUILDING NORTHWARD FROM THE NE GULF AND WRN ATLC WEDNESDAY INTO LATE THURSDAY AND SURFACE HIGH ALONG OR JUST OFF NE FL COAST...A GENERALLY WARM AND DRY FCST WILL OPEN THE EXTENDED PERIOD. HIGH MOVES FURTHER OFFSHORE ON THURSDAY AHEAD OF NEXT DEVELOPING SYSTEM. DIGGING SHORTWAVE FINALLY BREAKS DOWN RIDGE BEGINNING FRIDAY WHILE N-S VORTLOBE MOVES ACROSS SE CONUS SAT. AT SURFACE... SHORTWAVE HELPS TO DEFINE LOW WHICH DEVELOPS IN N TX WITH COLD FRONT EXTENDING SWD IN MEX BY 12Z THURS. LOW LIFTS RAPIDLY N/NE TO GREAT LAKES BY 12Z FRI WITH PRE-FRONTAL TROF ACROSS ALA AND PARENT FRONT THRU WRN TENN-ERN ARK...ERN MOST TX. GFS SHOWING PRE-FRONTAL CONVECTION MOVING ACROSS LOCAL AREA FRI AFTERNOON/NIGHT WITH FRONT MOVING ACROSS EARLY SAT. IN ITS WAKE HIGH PRESSURE BUILDS IN WITH DRY NW FLOW THRU AT LEAST SUNDAY EVE OR EARLY MON WHEN ANOTHER WEAK BAND MOISTURE IS POSSIBLE. 12Z ECMWF IS A BIT SLOWER ON THIS FRONTAL TIMING WITH CONVECTION NOT ARRIVING UNTIL FRIDAY NIGHT AND LINGERING INTO A GOOD PORTION OF SATURDAY. FOR CONTINUITY SAKE WILL STAY WITH THE GFS SOLUTION...HOWEVER TIMING OF FRONT MAY NEED TO BE ADJUSTED BACK IN FUTURE FORECAST PACKAGES...ESPECIALLY SINCE LATEST 00Z CANADIAN IS SHOWING STRONG SUPPORT FOR THE SLOWER ECMWF SOLUTION. UNTIL THE FRONT PASSES...TEMPS SHOULD CONTINUE ABOVE CLIMO...WITH INLAND HIGHS LIKELY REACHING THE LOWER TO MID 80S THRU FRI...THEN DROP TO MID-UPPER 70S SAT AND LOW-MID 70S SUNDAY BEFORE RISING UP TO CLIMO AGAIN ON MONDAY. INLAND LOW TEMPS WILL REMAIN ABOVE CLIMO... OR IN LOW 60S THRU SAT THEN IN WAKE OF FRONT DROP MID 40S SUN AND MID-UPPER 40S MON MORNING. && .AVIATION... FOR REST OF THE OVERNIGHT HOURS...AREAS OF FOG/LOW STRATUS ARE EXPECTED ACROSS THE TRI-STATE AREA WITH PLENTY OF SFC MOISTURE PRESENT AND DRIER AIR MOVING IN AT MID LEVELS PER WATER VAPOR IMAGERY. LIFR AND POSSIBLY VLIFR VIS NOT OUT OF THE QUESTION AND ALREADY OCCURRING AT DHN...VLD...TLH...ABY. PFN LIKELY TO ALSO GET THE LOW CEILINGS...BUT THE VSBY NOT ANTICIPATED TO BE QUITE AS LOW. AFT 14-15Z FOG AND LOW CIGS SHOULD SLOWLY LIFT WITH VFR CEILINGS AROUND 4 KFT UNTIL AROUND 20Z. DIFFICULT FORECAST FOR KABY TO KVLD AS LOWER LEVEL STRATUS MAY ATTEMPT TO HOLD ON THROUGH A GOOD PORTION OF THE DAY. ANY LOWER LEVEL (MVFR/IFR) STRATUS FROM KABY TO KVLD IS EXPECTED TO EXPAND SOUTH AND WEST THROUGH MONDAY NIGHT. && .MARINE... WEAK GRADIENT OVER THE FORECAST WATERS AS BOUNDARY CONTINUES TO SLOWLY SLIDE SOUTH AND EAST. HIGH PRESSURE WILL BUILD IN FROM THE NORTHEAST LATER TODAY INTO TONIGHT ALLOWING THE GRADIENT TO TIGHTEN. THIS SURFACE RIDGE WILL REMAIN IN CONTROL THROUGH TUESDAY NIGHT. EXPECT INCREASING FLOW FROM THE EAST TONIGHT AND AGAIN TUESDAY NIGHT WITH ASSOCIATED WITH NOCTURNAL SURGES WHICH ARE COMMON IN THESE SETUPS. WINDS AND SEAS NOW EXPECTED TO REACH CAUTION LEVELS... ESPECIALLY OVER THE OFFSHORE LEGS. FLOW BECOMES MORE SOUTHERLY DURING THE MIDDLE AND END OF THE WORK WEEK AS HIGH PRESSURE SLIDES EAST OFF THE SOUTHEAST COAST AND LOW PRESSURE BEGINS TO TAKE SHAPE WELL TO OUR WEST. && .FIRE WEATHER... ENOUGH LOW LEVEL MOISTURE WILL REMAIN IN PLACE THROUGH THE NEXT SEVERAL DAYS TO RESULT IN RH VALUES STAYING ABOVE CRITICAL LEVELS. RED FLAG CONDITIONS ARE NOT ANTICIPATED THROUGH AT LEAST WEDNESDAY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 81 59 80 59 81 / 10 10 0 0 10 PANAMA CITY 79 62 77 64 77 / 10 10 0 10 20 DOTHAN 80 59 77 60 80 / 10 10 0 10 20 ALBANY 77 57 75 58 80 / 20 10 0 0 10 VALDOSTA 80 57 77 55 82 / 20 10 0 0 10 CROSS CITY 82 57 81 57 82 / 10 10 0 0 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ AVIATION/FIRE WX...BLOCK PUBLIC/MARINE...MROCZKA LONG TERM...BLOCK/MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 835 PM EDT SUN APR 6 2008 .DISCUSSION...A STATIONARY FRONT CUT NORTHEAST TO SOUTHWEST ACROSS OUR GA ZONES AND THEN OFF THE FLORIDA COAST NEAR PENSACOLA AT 00Z. MEANWHILE...RUC ANALYSIS SHOWS A SHORTWAVE CROSSING NORTH FLORIDA NEAR OUR SE BIG BEND ZONES. MOST OF THE ASSOCIATED AREA OF CONVECTION WAS NOW SOUTH AND EAST OF OUR CWA. THE SHORTWAVE WILL MOVE EAST OF THE FLORIDA PENINSULA OVERNIGHT TAKING THE REMAINING SHOWERS WITH IT AND ALLOWING MUCH DRIER AIR TO FILTER INTO THE MID AND UPPER LEVELS IN ITS WAKE. SHOULD BE ABLE TO REMOVE ALL MENTION OF POPS FROM THE 1ST PERIOD OF THE ZONES. AS SKIES BEGIN TO CLEAR FROM WEST TO EAST...WE EXPECT WIDESPREAD STRATUS AND FOG TO DEVELOP AS LOW LEVEL MOISTURE REMAINS QUITE ABUNDANT...ESPECIALLY SOUTH OF THE FRONT WHERE DEW POINTS ARE IN THE MID TO UPPER 60S. && .AVIATION...OVERNIGHT...FOG IS EXPECTED ACROSS THE TRI-STATE AREA WITH PLENTY OF SFC MOISTURE PRESENT AND DRIER AIR MOVING IN AT MID LEVELS PER WATER VAPOR IMAGERY. CONDITIONS COULD GO AS LOW AS VLIFR FOR A FEW HOURS EITHER SIDE OF SUNRISE FOR DHN...VLD AND TLH. PFN AND ABY WILL ALSO GET THE LOW CEILINGS...BUT THE VSBY SHOULD NOT BE QUITE AS LOW. FOR MON...AFTER THE MORNING CONDITIONS IMPROVE... LOOK FOR VFR CEILINGS AROUND 4 KFT FOR MUCH OF THE DAY. && .MARINE...WINDS OVER THE COASTAL WATERS ARE GENERALLY RUNNING 10 TO 15 KNOTS. EXPECT THESE WINDS TO WEAKEN OVERNIGHT AS THE GRADIENT CONTINUES TO SLACK. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ SHORT TERM...BARRY AVIATION...WOOL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 230 PM EDT SUN APR 6 2008 .DISCUSSION... FOR THE REST OF THE AFTERNOON INTO EARLY EVENING...CONVECTION HAS FINALLY DEVELOPED ALONG THE WEST COAST SEA BREEZE ACROSS HENDRY AND COLLIER COUNTIES AND SHOULD CONTINUE MOVING NORTHEAST INTO THE LAKE OKEE REGION/PALM BEACH COUNTY. OTHER ISOLATED TO SCATTERED ACTIVITY MAY DEVELOP FURTHER SOUTH ACROSS MIAMI-DADE AND BROWARD COUNTIES WHERE THE EAST AND WEST COAST SEA BREEZES MERGE...AND THIS TREND SHOULD CONTINUE WITH SLOW NE MOVEMENT BACK TOWARDS THE METRO AREAS EXPECTED HERE AS WELL. COMPLEX/UNCERTAIN FORECAST SHAPING UP FOR THE NEXT 24 HOURS. CURRENTLY...SFC TROUGH LIES ACROSS NORTH FL/BIG BEND AREA. WATER VAPOR IMAGERY SHOWS ONE SHORTWAVE SOUTH OF THE FL PANHANDLE WITH AN ASSOCIATED LARGE CONVECTIVE MASS...AND RUC STREAMLINE ANALYSIS SHOWS GOOD UPPER DIVERGENCE ACROSS THE EASTERN GULF ALONG AND JUST EAST OF THIS DISTURBANCE. MODELS DIFFER IN THE DETAILS...WITH THE NAM12 SAGGING THE SURFACE TROUGH SOUTH TO CENTRAL FL BY 12Z TOMORROW...WHILE THE GFS KEEPS IT FURTHER NORTH. CONCERNING THE SHORTWAVE...THE GFS ELONGATES THE ASSOCIATED CONVECTIVE MASS MOVING ONE PIECE NE ACROSS N FL WHILE THE SOUTHERN PIECE BREAKS OFF AND MOVES E/SE AND SAGS ACROSS CENTRAL FL THIS EVENING/EARLY TONIGHT AND THEN INTO SOUTH FL LATER TONIGHT/EARLY TOMORROW MORNING AHEAD OF THE MAIN TROUGH AXIS. WHILE THE GFS SOLUTION LOOKS LIKE CONVECTIVE FEEDBACK...GIVEN THE UPPER DIVERGENCE IN THE GULF AND CURRENT CONVECTIVE TRENDS IT MAY ACTUALLY HAVE THE RIGHT IDEA...AND WILL LEAN TOWARDS ITS SOLUTION THE NEXT 24 HRS...GIVEN NAM APPEARS TO HAVE INITIALIZED A BIT TOO FAR SOUTH WITH THIS SHORTWAVE...AND GIVEN BROAD/DIFFUSE NATURE OF SURFACE TROUGH AND LACK OF AN UPSTREAM KICKER DO NOT FEEL IT WILL SAG THAT FAR SOUTH...REMAINING FURTHER NORTH OVERNIGHT LIKE THE 09Z SREF ENSEMBLE MEAN SUGGESTS...IN BETTER AGREEMENT WITH THE GFS. FORECAST WILL AGAIN BE HIGHLY DEPENDANT ON CONVECTIVE EVOLUTION ACROSS THE GULF THIS AFTERNOON/EVENING AND ANY ASSOCIATED BOUNDARIES THAT EMANATE FROM IT. WHATEVER CONVECTION THAT DOES MOVE THROUGH LATER TONIGHT/TOMORROW MORNING COULD BE SIMILAR TO LAST NIGHTS ROUND...WITH SOME STRONG WINDS OF 40 TO 50 MPH AND HEAVY RAINFALL...BUT EXPECT WEAK OVERALL SHEAR/LAPSE RATES AND NOCTURNAL COOLING WILL PREVENT A SEVERE WX OUTBREAK. SURFACE RIDGE BUILDING OVER THE MID ATLANTIC WILL FINALLY GIVE THE SFC TROUGH SOME PUSH THROUGH THE CWA MONDAY AFTERNOON. SFC FLOW VEERS TO SW OR WSW AHEAD OF IT WHICH SHOULD ALLOW THINGS TO WARM UP ACROSS THE SOUTHERN EAST COAST AREAS IF CONVECTIVE DEBRIS CAN CLEAR SOME. HIGHS COULD CLIMB INTO THE UPPER 80S AS A RESULT...BUT GIVEN HIGHLY UNCERTAIN CONVECTIVE EVOLUTION OVERNIGHT WILL NOT GO AS WARM AS THIS PATTERN FAVORS CLIMATOLOGICALLY. LOCATIONS TO THE NORTH SHOULD STAY COOLER AS WINDS SHIFT N AND THEN NE DURING THE AFTERNOON. MODELS CONTINUE TO GENERATE PRECIP AS THE TROUGH MOVES THROUGH TOMORROW AFTERNOON...BUT THIS AGAIN WILL BE DEPENDANT ON EVOLUTION TONIGHT. IF GFS SCENARIO DOES INDEED PAN OUT...WOULD EXPECT THE WSW SFC FLOW AHEAD OF THE TROUGH TO LIMIT MOISTURE RECOVERY AND CONVERGENCE...AND THUS LIMIT OVERALL PRECIP THREAT AFTER THE MORNING HOURS. THEREAFTER...SFC RIDGE MOVES SLOWLY INTO THE WESTERN ATLANTIC TUESDAY THROUGH THE END OF THE WEEK WITH PREVAILING NE FLOW...AND MID-LEVEL RIDGING BUILDS OVERHEAD. WHILE ENOUGH MOISTURE MAY LINGER FOR A FEW AFTERNOON SHOWERS ACROSS WESTERN AREAS TUESDAY...THE BULK OF THE REMAINDER OF THE WEEK LOOKS DRY AND WARM. IF THIS PATTERN DOES PAN OUT...STRONG SUBSIDENCE AND OFFSHORE FLOW COULD LEAD TO WARMER THAN GUIDANCE TEMPERATURES ALONG THE WEST COAST/NAPLES AREA ONCE AGAIN. && .AVIATION... VFR CONDITIONS ARE EXPECTED TO CONTINUE MOST OF THE TIME THROUGH MONDAY MORNING. HOWEVER BRIEF PERIODS OF IFR CONDITIONS ARE A DISTINCT POSSIBILITY PARTICULAR THIS AFTERNOON AND EVENING ALONG THE EAST COAST SITES WITH ANY THUNDERSTORM IN THE VICINITY. THIS POSSIBILITY IS HIGHEST FOR PBI THAN THE OTHER SITES. ADDITIONAL ACTIVITY IS LIKELY OVERNIGHT AS A FRONTAL TROUGH APPROACHES THE AREA FROM THE NORTH. ALTHOUGH HIGHLY UNCERTAIN AT THIS TIME...ANY STORM ACTIVITY ACCOMPANYING THIS FEATURE COULD ALSO RESULT IN BRIEF PERIODS OF IFR CONDITIONS. MAIN CONCERN ALONG WITH ANY OF THIS ACTIVITY WILL ALSO BE WIND SHIFTS ASSOCIATED WITH OUTFLOW BOUNDARIES. && .MARINE... S TO SW WINDS CONTINUE INTO TOMORROW MORNING AROUND 15 KTS...THEN BECOME NW THEN NE FROM NORTH TO SOUTH AS WEAK SURFACE TROUGH PASSES THROUGH. NE WINDS WILL CONTINUE INTO THE MIDDLE OF THE WEEK ACROSS THE LOCAL WATERS...AND IF SURFACE LOW DEVELOPS OFF THE CAROLINA COAST AS ADVERTISED BY SOME MODELS...THERE COULD BE A 3 TO 4 FT SWELL MOVING SW TO OUR LOCAL WATERS BEGINNING LATE WEDNESDAY AND LASTING THROUGH THURSDAY. FETCH AT THIS TIME WOULD FAVOR GREATEST IMPACT AT PALM BEACH COAST AS BAHAMAS WILL SHIELD AREAS FURTHER SOUTH FROM MORE THAN A 1 TO 2 FT SWELL. && .FIRE WEATHER... NO CONCERNS...SLIGHTLY LOWER DEWPOINTS WILL MOVE IN AND MIX DOWN ACROSS THE WESTERN INTERIOR TUESDAY AND WEDNESDAY...BUT RH`S SHOULD NOT DROP BELOW 40 PERCENT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 70 85 70 82 / 60 60 20 20 FORT LAUDERDALE 71 85 72 83 / 60 60 20 20 MIAMI 72 87 72 84 / 60 60 20 20 NAPLES 71 84 67 88 / 70 40 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE: STRASSBERG AVIATION: PS fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIAMI FL 1023 AM EDT SUN APR 6 2008 .UPDATE... MCS THAT MOVED ACROSS SOUTH FLORIDA HAS EXITED THE ATLANTIC WATERS THIS MORNING. THE CONVECTION WAS DRIVEN BY EITHER A MESOSCALE CONVECTIVE VORT AND/OR MESOLOW WHICH HAS BEEN EASY TO SEE SPINNING ACROSS THE SOUTH FLORIDA PENINSULA AND IS EXITING INTO THE ATLANTIC. THE MCS HAS LEFT A TRAILING OUTFLOW BOUNDARY WHICH HAS BECOME STATIONARY AND RUNS FROM THE SOUTH SIDE OF THE COMPLEX IN THE WESTERN BAHAMAS TO JUST SOUTH OF THE KEYS AND BACK WNW INTO THE EAST CENTRAL GULF WHERE IT MERGES WITH THE LEADING EDGE OF THE NEXT SOUTHERN STREAM SHORTWAVE. THIS SHORTWAVE HAS CAUSED A LARGE BLOWUP IN CONVECTION ALONG AND NORTH OF THE SHORTWAVES INTERSECTION WITH THE OUTFLOW BOUNDARY THIS MORNING. THE MAIN QUESTION TODAY IS GOING TO BE WHAT HAPPENS WITH ADDITIONAL CONVECTIVE DEVELOPMENT THIS AFTERNOON. THE ATMOSPHERE IS WORKED OVER AND FAIRLY STABLE RIGHT NOW...WITH LAPS AND RUC ANALYSIS SHOWING 200-300 J/KG OF CINH TO WORK THROUGH. SURFACE WINDS HAVE SWITCHED BACK TO THE PREVAILING SE DIRECTION...AND THIS SHOULD ALLOW AIRMASS RECOVERY TODAY GIVEN MUCH OF THE CONVECTIVE DEBRIS HAS ALREADY THINNED OUT...PLUS THE REGION REMAINS WITHIN THE ARCING DEEP MOISTURE PLUME AROUND THE WEST SIDE OF THE ATLANTIC RIDGE. LAPS ANALYSIS INDICATES RECOVERY IS ALREADY BEGINNING WITH SURFACE-BASED INSTABILITY INCREASING EASTWARD THROUGH THE GULF/FL KEYS. GIVEN THE LATEST TRENDS MENTIONED ABOVE...THINK THAT THE ATMOSPHERE WILL RECOVER SUFFICIENTLY TO SUPPORT CONVECTION BY EARLY TO MID AFTERNOON...ESPECIALLY AS TEMPS WARM INTO AT LEAST THE LOW 80S AND SEA BREEZES DEVELOP. STEERING FLOW WILL ALLOW ANY CONVECTION THAT FORMS TO WORK BACK TOWARDS THE EAST COAST. CURRENT FORECAST HAS THIS SITUATION HANDLED WELL...AND WILL ONLY UPDATE FOR CURRENT TRENDS AND LOWER POPS SOME FOR THE MORNING HOURS. IF ADDITIONAL CONVECTION CAN FORM SOUTH ALONG THE SHORTWAVE IN THE CENTRAL GULF...CURRENT TIMING WOULD HAVE IT ARRIVING ALONG THE WEST COAST AFTER 00Z...SO WE WILL HAVE TO MONITOR THAT SHORTWAVE AND ITS INTERACTION WITH THE REMNANT OUTFLOW BOUNDARY FOR CONVECTIVE DEVELOPMENT WHICH COULD IMPACT SOUTH FLORIDA THIS EVENING/EARLY TONIGHT...GIVEN STRONG DRY PUNCH NOTED BEHIND IT ON WATER VAPOR IMAGERY AND GOOD DIVERGENCE ALOFT OVER THE GULF. && .AVIATION... MID-LEVEL CLOUDS WILL THIN SOME AT THE EASTERN TERMINALS THROUGH EARLY AFTERNOON...WITH GENERALLY LIGHT SE WINDS EXPECTED TO PREVAIL. LIGHT FLOW AND HEATING WILL ALLOW SEA BREEZES TO DEVELOP ALONG BOTH COASTS THIS AFTERNOON...AND EXPECT TSRA TO DEVELOP AND IMPACT THE TERMINALS FOR THE MAJORITY OF THE AFTERNOON/EARLY EVENING HOURS. EXPECT SEVERAL ROUNDS MIGHT BE POSSIBLE WITH BRIEFLY REDUCED VSBYS/MVFR CIGS AND PSBL WIND GUSTS UP TO 45 MPH. UPDATE/AVIATION...STRASSBERG/PS && .PREV DISCUSSION... /ISSUED 536 AM EDT SUN APR 6 2008/ SYNOPSIS... CONVECTION ACROSS THE SOUTH FLORIDA PENINSULA AND SURROUNDING WATERS HAS BEEN VERY ACTIVE DURING THE EARLY MORNING HOURS...WITH THE LEADING EDGE OF THE CONVECTION ASSOCIATED WITH A STRONG GUST FRONT NOW OVER THE SOUTHEASTERN PORTIONS OF SOUTH FLORIDA AND EXITING INTO THE ATLANTIC WATERS. AFTER THE PASSAGE OF THE GUST FRONT ADDITIONAL RAIN WILL CONTINUE ACROSS THE REGION BUT MORE STRATI FORM IN NATURE. ADDITIONAL CONVECTION IS EXPECTED AGAIN THIS AFTERNOON...BUT THE CLOUDINESS OVER THE REGION WILL HELP TO SUPPRESS IT SOME. HOWEVER...THE MID TO UPPER LEVEL TROUGH CONTINUES TO INFLUENCE THE REGION AND SYNOPTIC SCALE LIFT AHEAD OF THE FRONT SHOULD LEAD TO ADDITIONAL CHANCES OF CONVECTION THIS AFTERNOON WITH THE DAY TIME HEATING. WITH ANY ADDITIONAL CONVECTION...A FEW STRONG THUNDERSTORMS ARE POSSIBLE BUT THE MAIN HAZARDS SHOULD BE CONFINED TO DAMAGING WINDS AND/OR POSSIBLE HAIL. AFTER TODAY...THE MID TO UPPER LEVEL TROUGH WILL STILL INFLUENCE THE REGION ON MONDAY AND THE BOUNDARY MOISTURE WILL STILL LINGER WITH SOME CONVECTIVE ACTIVITY POSSIBLE...BUT EXPECTED TO BE MAINLY IN THE AFTERNOON AND MORE SCATTERED IN NATURE. THEREAFTER...CHANCES OF CONVECTION WILL BEGIN TO DIMINISH. AVIATION... CONVECTION ASSOCIATED WITH A GUST FRONT EARLY THIS MORNING IS AFFECTING THE EASTERN COASTAL ZONES AND THE EASTERN TERMINALS. FOR THE SHORT TERM FOR THE EAST COAST TERMINALS...EXPECT TO HAVE VCTS WITH PERIODS OF MVFR CONDITIONS POSSIBLE AND VERY BRIEF PERIODS OF IFR CONDITIONS POSSIBLE OVER THE NEXT HOUR OR TWO. THEREAFTER....STRATI FORM RAIN SHOULD PREVAIL INTO THE MID MORNING HOURS WITH ISOLATED THUNDERSTORMS POSSIBLE AND BRIEF PERIODS OF MVFR POSSIBLE. FOR TERMINAL KAPF...MAINLY STRATI FORM RAIN WILL CONTINUE INTO THE MID MORNING HOURS WITH BRIEF PERIODS OF MVFR CONDITIONS POSSIBLE...BUT AN ISOLATED THUNDERSTORM IS POSSIBLE. FOR ALL TERMINALS...CONVECTION COULD BEGIN AGAIN IN THE AFTERNOON...WITH PERIODS OF MFVR POSSIBLE AND BRIEF PERIODS OF IFR POSSIBLE WITH ANY THUNDERSTORMS. MARINE... A LONG PERIOD SWELL HAS BEEN INTRODUCED INTO THE LONG TERM FORECAST...WITH A NORTH NORTHEAST SWELL FORECAST TO ENTER THE WATERS EAST OF PALM BEACH COUNTY LATE WEDNESDAY INTO THURSDAY...WITH 3 TO 4 FEET POSSIBLY REACHING THESE WATERS. THIS SWELL IS FORECAST TO BE GENERATED BY A DEVELOPING LOW EAST OF THE CAROLINAS. FIRE WEATHER... NO FIRE WEATHER CONCERNS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 85 70 85 69 / 70 50 50 20 FORT LAUDERDALE 84 72 85 71 / 70 50 50 20 MIAMI 85 71 86 71 / 70 50 50 20 NAPLES 84 71 84 67 / 50 40 40 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...60/BD SHORT TERM/AVIATION...70/DD fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1215 PM CDT SUN APR 6 2008 .DISCUSSION... ISSUED 1030 AM CDT SUN APR 6 2008 MORNING FORECAST PACKAGE APPEARS ON TRACK AND DO NOT PLAN ANY ADJUSTMENTS AT THIS TIME. LOW PRESSURE CENTERED OVER EASTERN SOUTH DAKOTA HAS A COLD FRONT EXTENDING SOUTH INTO EASTERN KANSAS AND CENTRAL OKLAHOMA. ISOLATED HIGH-BASED CONVECTION HAS BEEN OBSERVED THIS MORNING AHEAD OF THE FRONT IN WESTERN MISSOURI. MID LEVEL LAPSE RATES AHEAD OF THE FRONT ARE SOMEWHAT STEEP /21 DEG 700-500 DELTA-T/...BUT LOW LEVEL MOISTURE IS QUITE SPARSE. WHAT LITTLE MOISTURE THERE IS ON UPSTREAM 12Z SOUNDINGS IS SHALLOW AND DOES NOT EVEN MAKE IT UP TO 850 MB. AS A CONSEQUENCE...THINK THAT THE RUC MODEL FORECAST OF LOWER 50S SURFACE DEWPOINTS LATE THIS AFTERNOON IS ON THE GENEROUS SIDE. THEREFORE... DESPITE IMPRESSIVE DYNAMICS AND COOL TEMPERATURES ALOFT WITH THE ASSOCIATED UPPER LOW OVER SOUTH DAKOTA...ANY CONVECTION THAT GETS GOING ALONG THE FRONT AS IT APPROACHES THE MISSISSIPPI RIVER THIS FAR SOUTH WILL LIKELY BE ISOLATED. 04 && .AVIATION... ISSUED 1215 PM CDT SUN APR 6 2008 VFR CONDITIONS WILL PREVAIL ACROSS AREA TAF SITES THROUGH 18Z MON. SCATTERED VFR CUMULUS WILL BE POSSIBLE DEC/CMI 18Z-23Z TODAY... OTHERWISE CEILINGS WILL BE UNLIMITED WITH SOUTHERLY/SOUTHEASTERLY LOW LEVEL FLOW 12-18 KT THROUGH 01Z MON. A FEW GUSTS 20-25 KT AS WELL. LOW PRESSURE CURRENTLY LOCATED SOUTHWESTERN MINNESOTA WITH COLD FRONT EXTENDING SOUTH ACROSS EASTERN KANSAS INTO CENTRAL OKLAHOMA. THIS FRONT WILL MOVE THROUGH THE CENTRAL ILLINOIS TAF SITES IN THE 09Z-12Z MON TIMEFRAME...WITH THICKENING STRATOCU AROUND 5K FT AHEAD OF IT. A FEW HIGH-BASED SHOWERS WILL BE POSSIBLE AROUND PIA AHEAD OF THE FRONT 03Z-08Z...BUT INSTABILITY IS FORECAST TO BE TOO WEAK FOR ANYTHING MORE THAN ISOLATED CONVECTION. CHANCES FOR ANY PRECIPITATION AT ANY ONE PLACE IS TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME. CLOUDS WILL CLEAR OUT WITH FRONTAL PASSAGE...LEAVING MAINLY CLEAR SKIES. SURFACE WINDS AFTER FRONTAL PASSAGE SOUTHWEST 5-10 KT WILL BECOME WESTERLY 10-15 KT AFTER 14Z MON. 04 && .PREV DISCUSSION... ISSUED 332 AM CDT SUN APR 6 2008 FORECAST MODELS STILL DIFFER IN THE DETAILS...BUT ANY WAY YOU SHAKE IT...A VERY ACTIVE WEEK IS IN STORE FOR THE REGION WEATHER WISE. A SERIES OF THREE DISTURBANCES...EACH ONE MORE IMPRESSIVE THAN THE LAST...WILL AFFECT THE AREA THROUGH THE WEEK. SHORT TERM...TODAY THROUGH TUESDAY. EXPECT ANOTHER BEAUTIFUL DAY THIS AFTERNOON ACROSS THE REGION. SUNSHINE WILL BE FILTERED BY SOME HIGH CLOUDS WHICH ARE SPREADING INTO THE AREA FROM WEST OF THE MISSISSIPPI... AND SHOULD HANG AROUND FOR MUCH OF THE DAY WITH DIFFLUENT FLOW HIGH ALOFT. DESPITE THE FILTERED SUNSHINE... TEMPERATURES SHOULD MAKE IT INTO THE 60S ACROSS THE ENTIRE CWA. PLAYED TEMPS ON THE COOLER SIDE OF MODEL GUIDANCE CONSIDERING A FEW MODELS WENT A LITTLE TOO WARM YESTERDAY... AND TODAY WE WILL HAVE THE ADDED VARIABLE OF HIGH CLOUDS... AND IT IS OFTEN DIFFICULT TO JUDGE JUST HOW THICK THEY WILL BECOME. HOWEVER...INCREASING LOW LEVEL WARM ADVECTION WILL HELP BALANCE OUT THIS LIMITING FACTOR. SHORTWAVE DISTURBANCE THAT WAS OVER NORTHERN IDAHO 24 HOURS AGO IS NOW ROLLING INTO SOUTH DAKOTA...AND IS EXPECTED TO MOVE ACROSS THE UPPER MIDWEST TONIGHT. ATTENDANT SFC COLD FRONT WILL MOVE ACROSS ILLINOIS BETWEEN MIDNIGHT TONIGHT AND DAWN TUESDAY WITH LITTLE FANFARE COMPARED TO WHAT WILL BE HAPPENING LATER IN THE WEEK. JUST NOT ENOUGH MOISTURE FOR THIS SYSTEM TO WORK WITH... AND IN ITS HIGHLY OCCLUDED STATE... THE STRONGEST DYNAMICS WILL BE VERY MUCH CONFINED TO RIGHT NEAR THE MID LEVEL LOW TRACK. KEPT A LOW CHANCE POP IN FOR THE OVERNIGHT HOURS... MAINLY FOCUSED ACROSS THE WESTERN AND NORTHERN PARTS OF THE CWA. MODELS HAVE BEEN IN THE MIDDLE OF A FLIP FLOP OVER THE PAST 24 HOURS. YESTERDAY I MENTIONED THE MODELS WERE TRENDING TOWARDS THE MORE AMPLIFIED SOLUTION WITH A FARTHER NW SFC LOW TRACK FOR TUE-WED... AND FELT THIS WAS THE WAY TO GO GIVEN BLOCKING PATTERN DOWNSTREAM. THEN THE 12Z RUNS CAME IN BRINGING EVERYTHING FARTHER SOUTHEAST AGAIN. 00Z OPERATIONAL RUNS WERE SIMILAR TO 12Z RUNS...WITH THE NOTABLE EXCEPTION OF THE 00Z ECMWF WHICH RESUMED THE MORE NORTHWEST TRACK. 00Z GFS ENSEMBLES AND 21Z SREF BOTH INDICATE THERE IS STILL A FAIRLY WIDE SPREAD OF SOLUTIONS...NOTE THE 00Z OPERATIONAL GFS WAS ON THE FAR SOUTHEAST EDGE OF THE ENSEMBLE SPREAD... AND THE PARALLEL GFS ALSO WAS FARTHER NORTHWEST. LOCAL 80KM ARW MODEL WHICH USES GFS FOR BOUNDARY CONDITIONS ALSO WAS MUCH NW OF THE GFS LOW TRACK. BOTTOM LINE... DO NOT THINK IT IS WISE TO TOSS ALL THE FORECAST EGGS IN ONE MODEL RUNS BASKET...ESPECIALLY WHEN THE OVERALL DIFFERENCES WITH MASS FIELDS ARE MINOR... BUT IT MAKES A FAIRLY BIG DIFFERENCE IN SENSIBLE WX. EXAMINATION OF MODEL SOLUTIONS DID NOT COME UP WITH ANY OBVIOUS REASONS TO FAVOR ONE SOLUTION OVER THE OTHER. SO... TOOK THE PROVERBIAL MIDDLE ROAD AND USED THE PROVERBIAL BLEND OF THE ECMWF/GFS WHEN EDITING GRIDS FOR TUE AND WEDNESDAY. SPC DAY 3 OUTLOOK HAS ENTIRE CWA IN A SLIGHT RISK FOR TUESDAY...AND GIVEN IMPRESSIVE DYNAMICS AND SHEAR... IT IS WELL WARRANTED. UNLESS THE SFC LOW TAKES THE FAR NORTHWEST TRACK... THE ACTUAL SVR WX THREAT AREA WILL LIKELY BE SMALLER. GIVEN THE SHEAR IN PLACE... I AM LEERY OF THE POSITION OF THE SFC WARM FRONT WHICH IS LIKELY TO BISECT SOME PART OF OUR CWA TUE. LOCALLY BACKED SFC FLOW INVOF WARM FRONT COULD INCREASE RISK OF TORNADOES...AND SPC HAS THIS OUTLINED IN THE SWODY3 AS WELL...SO WELCOME TO SPRING. LONG TERM...WEDNESDAY AND THURSDAY. AS IF ONE SYSTEM WAS NOT ENOUGH...GFS/ECMWF/GEM GLOBAL ALL INDICATING ANOTHER STRONG NEGATIVELY TILTED TROUGH... THIS ONE EVEN DEEPER/STRONGER THAN THE EARLIER ONE... WILL MOVE ACROSS THE MID MISSISSIPPI VALLEY THURSDAY... BRINGING ANOTHER GOOD CHANCE FOR LOCALLY HEAVY RAINFALL AND SEVERE WEATHER. INCREASED POPS TO LIKELY... A RARE MOVE FOR DAY 5... GIVEN THE CONSISTENTLY STRONG SIGNAL. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 124 PM EDT MON APR 7 2008 .AVIATION (18Z TAFS)... VFR CONDITIONS WILL BE FOUND THRU THE ENTIRE PERIOD...WITH THE MAIN CONCERN BEING THE GUSTY WESTERLY WINDS WITH GUSTS AT OR JUST ABV 25 KTS POSSIBLE THRU THE EARLY EVENING. WINDS WILL WEAKEN AFT 00Z WITH LIGHT AND VARIABLE WINDS OVERNIGHT. MODEST SOUTHEAST WINDS AFTER 15-16Z. NO CIGS EXPECTED BELOW 12K FT THRU THE PERIOD. && .PREV DISCUSSION... /ISSUED 1037 AM EDT MON APR 7 2008/ UPDATE... DRY AND CLOUDLESS SFC FRONT STARTING TO PUSH INTO THE REGION FROM THE WEST...JET STREAK CI PUSHING NORTHEAST ACROSS SW INDIANA INTO NORTHWEST OHIO. HAVE MADE SOME ADJUSTMENTS TO THE SHORT TERM FORECAST...MAINLY TO REMOVE MOST IF NOT ALL OF THE CLOUDS FOR THE DAY...LEAVING SOME CI/FEW CU IN THE EASTERN PORTIONS OF THE REGION WHERE JUST A BIT MORE MOISTURE EXISTS. TWEAKED TEMPS SOME BLENDING THE LATEST DATA FROM THE OBS AND RUC13 WITH THE EXISTING FORECAST TO CATCH LATEST TEMPS AND DEWPT TRENDS...THIS DID CREATE SLIGHT DIFFERENCES WITH THE AFTN HIGHS...SLIGHTLY HIGHER EAST...AND NEAR THE SAME OR SLIGHTLY LOWER WEST BEHIND THE FRONT AS COOLER TEMPS ADVECT INTO THE REGION. GUSTY WINDS STILL LOOK LIKELY AS THE FRONT PASSES THIS AFTERNOON. PREV DISCUSSION... /ISSUED 545 AM EDT MON APR 7 2008/ SHORT TERM... TODAY AND TONIGHT...A WEAK COLD FRONT WILL RACE EAST INTO THE FORECAST AREA TODAY...ACCOMPANIED BY WINDS SHIFTING TO THE WEST. SOME SPRINKLES MAY ACCOMPANY THE FRONT GIVEN SOME MID LEVEL FORCING. GIVEN ONGOING LIGHT SHOWERS WEST OF THE AREA...HAVE ADDED SPRINKLES EARLY TODAY OVER FAR SOUTHERN LOWER MICHIGAN INTO EXTREME NORTHERN INDIANA. WINDS SHOULD DIMINISH RAPIDLY EARLY THIS EVENING AS THE PRESSURE GRADIENT SLACKENS AND AS THE FRONT BECOMES STATIONARY JUST SOUTHEAST OF THE AREA. LONG TERM... TUESDAY THROUGH SUNDAY. PRIMARY FOCUS ON DELAY OF ONSET OF TSRA CHCS TUESDAY COINCIDENT WITH FOCUS AND BETTER 1000-925MB THETA-E RETURN FLOW/MFLUX CONVERGENCE LIMITED LARGELY TO EVENING/OVERNIGHT IN ADVANCE OF FRONTAL PASSAGE. FIRST S/W NEAR KMPX TO LIFT QUICKLY NEWD INTO SRN ONT...MEANWHILE B.C./WA COAST WAVE EXTENDING SWD TO OR/NRN CA W/STRONG STRATOSPHERIC INTRUSION TO REEMERGE BY 00 UTC TUE ALONG FRONT RANGE OF CNTL ROCKIES FORCING STRONG LEESIDE CYCLOGENSIS EARLY TUE. 06/12Z ECMWF TOO FAST WITH FRONT...NAM/GFS PRETTY MUCH IN GOOD AGREEMENT. QUESTION REMAINS ON DEGREE OF INSTABILITY. MODIFIED SFC PARCELS IN SRN CWA YIELD AROUND 1000 J/KG SBCAPES WITH WINDEX TO 42 KTS/FAVORABLE WBZERO HEIGHTS AROUND 9KFT. AROUND 40 KTS DEEP BULK SHEAR PERPENDICULAR TO FRONT WITH 60-70KT 5H JETLET SUGGESTIVE OF SOME STORM ORGANIZATION POTENTIAL WITH CONDITIONAL LEWP DEVELOPMENT/WIND THREAT. DUE TO CONDITIONAL NATURE PRIMARILY WITH MEAGER INSTABILITY WILL CONTINUE TO ADDRESS IN HWO. GAVE TIGHTER PRECIP GRADIENT WED AM ASSOCIATED WITH FRONT AND TIMED TSRA/SHRA OUT OF CWA BY WED AFTN. REMOVED ALL MENTION OF SHRA WED NIGHT AS 1000-700 MB LAYER MARKEDLY DRY WITH FROPA. UNCERTAINTY WRT HIGH PRECISION IN DY4 TSRA FCST ESPCLY AS ECMWF/GFS SPREAD INCREASES WITH FINAL EJECTION OF SWRN STATES TROF. CERTAINLY UNSETTLED PD AND WITH FRONTAL BNDRY IN PLAY/LIFTING BACK NWD OPTED FOR CHC TSRA THU/THU NIGHT PENDING MESOSCALE FEATURES/TIMING COMING MORE TO LIGHT. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SKIPPER LONG TERM...MURPHY AVIATION/UPDATE...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1037 AM EDT MON APR 7 2008 .UPDATE... DRY AND CLOUDLESS SFC FRONT STARTING TO PUSH INTO THE REGION FROM THE WEST...JET STREAK CI PUSHING NORTHEAST ACROSS SW INDIANA INTO NORTHWEST OHIO. HAVE MADE SOME ADJUSTMENTS TO THE SHORT TERM FORECAST...MAINLY TO REMOVE MOST IF NOT ALL OF THE CLOUDS FOR THE DAY...LEAVING SOME CI/FEW CU IN THE EASTERN PORTIONS OF THE REGION WHERE JUST A BIT MORE MOISTURE EXISTS. TWEAKED TEMPS SOME BLENDING THE LATEST DATA FROM THE OBS AND RUC13 WITH THE EXISTING FORECAST TO CATCH LATEST TEMPS AND DEWPT TRENDS...THIS DID CREATE SLIGHT DIFFERENCES WITH THE AFTN HIGHS...SLIGHTLY HIGHER EAST...AND NEAR THE SAME OR SLIGHTLY LOWER WEST BEHIND THE FRONT AS COOLER TEMPS ADVECT INTO THE REGION. GUSTY WINDS STILL LOOK LIKELY AS THE FRONT PASSES THIS AFTERNOON. && .PREV DISCUSSION... /ISSUED 545 AM EDT MON APR 7 2008/ SHORT TERM... TODAY AND TONIGHT...A WEAK COLD FRONT WILL RACE EAST INTO THE FORECAST AREA TODAY...ACCOMPANIED BY WINDS SHIFTING TO THE WEST. SOME SPRINKLES MAY ACCOMPANY THE FRONT GIVEN SOME MID LEVEL FORCING. GIVEN ONGOING LIGHT SHOWERS WEST OF THE AREA...HAVE ADDED SPRINKLES EARLY TODAY OVER FAR SOUTHERN LOWER MICHIGAN INTO EXTREME NORTHERN INDIANA. WINDS SHOULD DIMINISH RAPIDLY EARLY THIS EVENING AS THE PRESSURE GRADIENT SLACKENS AND AS THE FRONT BECOMES STATIONARY JUST SOUTHEAST OF THE AREA. LONG TERM... TUESDAY THROUGH SUNDAY. PRIMARY FOCUS ON DELAY OF ONSET OF TSRA CHCS TUESDAY COINCIDENT WITH FOCUS AND BETTER 1000-925MB THETA-E RETURN FLOW/MFLUX CONVERGENCE LIMITED LARGELY TO EVENING/OVERNIGHT IN ADVANCE OF FRONTAL PASSAGE. FIRST S/W NEAR KMPX TO LIFT QUICKLY NEWD INTO SRN ONT...MEANWHILE B.C./WA COAST WAVE EXTENDING SWD TO OR/NRN CA W/STRONG STRATOSPHERIC INTRUSION TO REEMERGE BY 00 UTC TUE ALONG FRONT RANGE OF CNTL ROCKIES FORCING STRONG LEESIDE CYCLOGENSIS EARLY TUE. 06/12Z ECMWF TOO FAST WITH FRONT...NAM/GFS PRETTY MUCH IN GOOD AGREEMENT. QUESTION REMAINS ON DEGREE OF INSTABILITY. MODIFIED SFC PARCELS IN SRN CWA YIELD AROUND 1000 J/KG SBCAPES WITH WINDEX TO 42 KTS/FAVORABLE WBZERO HEIGHTS AROUND 9KFT. AROUND 40 KTS DEEP BULK SHEAR PERPENDICULAR TO FRONT WITH 60-70KT 5H JETLET SUGGESTIVE OF SOME STORM ORGANIZATION POTENTIAL WITH CONDITIONAL LEWP DEVELOPMENT/WIND THREAT. DUE TO CONDITIONAL NATURE PRIMARILY WITH MEAGER INSTABILITY WILL CONTINUE TO ADDRESS IN HWO. GAVE TIGHTER PRECIP GRADIENT WED AM ASSOCIATED WITH FRONT AND TIMED TSRA/SHRA OUT OF CWA BY WED AFTN. REMOVED ALL MENTION OF SHRA WED NIGHT AS 1000-700 MB LAYER MARKEDLY DRY WITH FROPA. UNCERTAINTY WRT HIGH PRECISION IN DY4 TSRA FCST ESPCLY AS ECMWF/GFS SPREAD INCREASES WITH FINAL EJECTION OF SWRN STATES TROF. CERTAINLY UNSETTLED PD AND WITH FRONTAL BNDRY IN PLAY/LIFTING BACK NWD OPTED FOR CHC TSRA THU/THU NIGHT PENDING MESOSCALE FEATURES/TIMING COMING MORE TO LIGHT. PREV DISCUSSION... /ISSUED 736 AM EDT MON APR 7 2008/ AVIATION (12Z TAFS)... VFR CONDITIONS WILL CONTINUE THRU THE PERIOD...WINDS WILL BE THE BIGGEST ISSUE WITH MODERATE SOUTHWESTERLIES WITH GUSTS TO 25 KTS THIS AFTERNOON AND EARLY EVENING. WINDS WILL LESSEN LATER IN THE EVENING AND VEER MORE TO THE WEST WITH HIGH CIGS AROUND 20K POSSIBLE. EVENTUALLY THE WINDS WILL BECOME LIGHT AND VARIABLE THRU THE END OF THE PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SKIPPER LONG TERM...MURPHY UPDATE...SCHOTT in AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 950 PM CDT MON APR 7 2008 .UPDATED PUBLIC DISCUSSION. .DISCUSSION... STILL SOME UNCERTAINTY FOR PTYPE THROUGH ALL OF TUESDAY. HAVE ADDED CHANCE SNOW IN THE MORNING ALONG WITH THE EXPECTED RAIN. LOTS OF DRY AIR AT H850 THIS EVENING AND NEW NAM...THOUGH NAM ISNT INITIALIZING THE EXTENT OF QPF PRESENTLY...IT CONTINUES TO POINT TOWARD A FASTER RAIN/SNOW CHANGEOVER FOR THE LATE MORNING AND AFTERNOON HOURS. SFC TEMPS MAY BE WARM ENOUGH TO KEEP A MIX GOING...ONCE IT BEGINS... THOUGH IF SHOWERS ARE HEAVY ENOUGH...WE COULD HAVE A SITUATION SIMILAR TO LAST THURSDAY WITH AN AREA OF WET SNOW SURROUNDED BY AREAS OF RAINFALL. FOR THE MOMENT THE SNOW OVER NE HAS LESSENED. WILL BE LOOKING AT LATEST GFS AND RUC CLOSELY. EARLIER...UPDATED ZONES FOR INCREASED AREAL COVERAGE OF SHOWERS SOUTH. ALREADY GETTING MEASURABLE ALONG THE BORDER COUNTIES. LOTS OF VIRGA OUTSIDE ATTM WITH DRY LAYER BEGINNING TO FILL IN. SNOW CONTINUES OVER SOUTH CENTRAL NE AND WILL BE LOOKING CLOSELY AT UPPER AIR/NEW MODEL OUTPUT OVER THE NEXT SEVERAL HOURS FOR ANY SIGN OF PTYPE ISSUES TUES./REV .PREVIOUS DISCUSSION... AN ACTIVE WEATHER PATTERN REMAINS IN STORE FOR CENTRAL IOWA THROUGH THE FORECAST PERIOD. WATER VAPOR SHOWING AN UPPER LEVEL SHORTWAVE CROSSING THE ROCKIES AND TRYING TO FORM WHAT LOOKS LIKE A BAROCLINIC LEAF ON THE LEE SIDE. AT THE SURFACE...LOW PRESSURE ACROSS TX/NEW MEXICO WILL LIFT NORTHEAST OVERNIGHT. A WARM FRONT EXTENDS FROM THE LOW INTO OK AND SRN MO. OVERRUNNING SETTING UP AND PRODUCING SCATTERED SHOWERS MAINLY OVER KS AND NEB. AS THE SHORTWAVE MOVES IN IT SHOULD ENHANCE ACTIVITY ALONG AND NORTH OF THE FRONT. FROM THE LOOKS OF THINGS THE BETTER MOISTURE WILL STAY TO THE SOUTH OF IOWA AND THUS ONLY MEAGER CAPE VALUES TONIGHT AND WEDNESDAY. THERE SHOULD BE ENOUGH FOR SOME ISOLATED THUNDER NEAR THE BOUNDARY. THIS SHOULD COME CLOSE ENOUGH TO IOWA TO GIVE A SMALL PORTION OF SE IA A SHOT AT SOME THUNDER. SHEAR IS DECENT WITH THIS SYSTEM BUT WITH VERY LOW CAPES AND THE AREA NOT GETTING INTO THE WARM SECTOR AT ALL I WOULD EXPECT ELEVATED STORMS THOUGH SEVERE POTENTIAL NOT LOOKING LIKE MUCH AT THIS POINT. QPF HOWEVER LOOKS PRETTY GOOD AS A BETTER MOISTURE TAP OCCURS BY 18Z TUES. SYSTEM LIFTS OUT BY LATE TUESDAY. THERE WILL THEN BE A BRIEF RESPITE ON WEDNESDAY AS HIGH PRESSURE MOVES IN THEN DEPARTS BY MID EVENING. THE NEXT SYSTEM THEN BEGINS TO LIFT OUT OF THE SOUTHERN PLAINS FOR WEDNESDAY NIGHT AND THURSDAY. MODELS CONTINUE TO DISAGREE MAINLY ON TIMING BUT GENERAL TRENDS ARE TO LIFT THE LOW OUT OF THE SOUTHERN PLAINS AND ACROSS IOWA BY LATE THURSDAY NIGHT. THERE IS ALSO SOME QUESTION AS TO HOW MUCH COLD AIR THIS SYSTEM WILL TAP INTO. THE GFS IS SLOWER WITH THIS SYSTEM AND THUS ALLOWS A LITTLE MORE COLD AIR INTO THE NW. THE EURO HAS A BIGGER GULF TAP AND PUTS THE WARM SECTOR INTO MORE INTO EASTERN IOWA THEN AS THE SYSTEM MOVES NE COLDER AIR PUSHES IN LATER THURSDAY NIGHT AND LINGERS THROUGH FRIDAY. GIVEN THE STRENGTH OF THE UPPER LOW I LIKE THE SLOWER GFS BUT THINK THAT THE WARM SECTOR WILL MAKE ITS WAY INTO SOUTHEAST IOWA. IN SHORT I WENT WITH A BLEND OF THE GFS/EURO. THIS COULD BE A POTENTIAL SNOW PRODUCER FOR LOCATIONS NORTH OF IOWA BUT WILL MONITOR FOR THE POTENTIAL TO SLIP INTO NORTHERN IOWA THURSDAY NIGHT. && .AVIATION...08/00Z COMPLICATED FORECAST FOR THIS TAF PERIOD. CONTINUE TO SEE MODERATE OVERRUNNING PRECIP ACROSS KS AND NE ATTM WITH RAIN/SNOW AND SOME THUNDER ALREADY OCCURRING. MODELS CONTINUE TO INITIALIZE THE SFC FEATURE POORLY WITH THE 18Z RUN. GFS/NAM QUITE DIFFERENT BUT AM LEANING TOWARD A NAM/EURO COMPROMISE FOR TUES. DRY POOL AT THE SFC AND ALOFT SETS THE STAGE FOR A MIX OF PRECIP OVER MUCH OF THE AREA ALONG AND NORTH OF I80 SO WILL CONTINUE RASN AND LOWER CIGS VSBYS THERE FOR THE LATE MORNING AND AFTERNOON HOURS. CURRENTLY AM GOING WITH LOW MVFR CIGS. POTENTIAL FOR LOWER CIGS TUES 12Z-20Z IF THE PRECIP CHANGES OVER TO SNOW. WILL BE MONITORING TRENDS THIS EVENING AND UPDATING PACKAGE IF NECESSARY. /REV && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...MS APR 08/REV AVIATION...REV LONG TERM...FAB ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 344 PM CDT MON APR 7 2008 .DISCUSSION... DAYS 1-2... A PROGRESSIVE SHORTWAVE TROUGH AND JET STREAK WILL MOVE ACROSS KANSAS TONIGHT. AHEAD OF THE SHORTWAVE, STRONG ELEVATED WARM ADVECTION WILL DEVELOP FROM 900 TO 750MB. MODEL SOUNDINGS SHOW CONSIDERABLE ELEVATED CAPE BASED AT THE ELEVATED FRONTAL SURFACE. THE NAM WAS MUCH FURTHER WEST WITH THIS ELEVATED INSTABILITY THAN THE GFS/UKMET. IN SUCH A PROGRESSIVE FLOW REGIME, CLIMATOLOGY SUGGESTS THAT THE BEST CHANCE FOR STORMS WILL BE IN OUR EASTERN COUNTIES. ASIDE FROM THE THUNDERSTORMS, STRONG WARM ADVECTION BELOW THE CAP WILL RESULT IN WIDESPREAD LIGHT RAIN OR DRIZZLE. DESPITE THE NAM`S HEAVY PRECIP, I SUSPECT THAT AMOUNTS WILL BE FAIRLY LOW IN OUR WESTERN COUNTIES, PERHAPS A FEW HUNDREDTHS OF AN INCH. BUT PLACES EAST OF DODGE CITY INCLUDING STAFFORD AND PRATT COULD RECEIVE UP TO AN INCH. SOME SNOW COULD MIX WITH THE RAIN IN OUR FAR NW BEFORE THE PRECIP ENDS, BUT THIS SHOULD BE FAIRLY LIGHT. NAM/RUC SFC TEMPS WERE GENERALLY ACCEPTED FOR 12Z TUE WITH LOWS FROM 33 TO 41 FROM NW TO SE. WIDESPREAD CLOUD COVER SHOULD HOLD MAXES DOWN TUESDAY, BUT SOME BREAKS IN THE AFTERNOON MAY ALLOW FOR SOME LOWER 50S IN DDC AND UPPER 50S IN THE SW CORNER. THE MODELS ARE CONVERGING ON THE ECMWF SOLUTION FOR THE NEXT SYSTEM WITH STRONG BAROCLINIC DEVELOPMENT ACROSS THE PLAINS. BUT IT APPEARS THAT THE STORM TRACK WILL BE OVER DODGE CITY, SO THE DRY INTRUSION MAY COME INTO PLAY. BUT DECENT LIFT AHEAD OF THE SYSTEM SHOULD RESULT IN WIDESPREAD AREAS OF RAIN BEGINNING WEDNESDAY. DAYS 3-7... MODELS REMAIN IN GOOD AGREEMENT WITH BRINGING OUR NEXT SIGNIFICANT UPPER LEVEL SYSTEM INTO THE CNTL PLAINS BY THURSDAY. BASED ON THE WAA DEVELOPING AHEAD OF 25H JET ACROSS NRN OK/SC KS IT CURRENTLY APPEARS THAT E/SE CWA WILL HAVE THE BETTER OPPORTUNITY FOR PCPN WEDNESDAY NIGHT. BY THURSDAY THE UPPER TROF/LOW WILL CROSS INTO THE CNTL PLAINS AND DEEPEN AS MID LVL MOISTURE BEGINS TO WRAP AROUND THIS DEEPENING SYSTEM. LLVL WAA AND 85H-7H FGEN PROGGED TO INCREASES ACROSS NW KS NEAR OUR NW CWA THURSDAY AFTERNOON WITH BOTH THE GFS AND ECMWF SUGGESTING THAT THIS AREA OF ENHANCED VVEL SLOWLY SHIFTING EASTWARD ACROSS CWA THROUGH EARLY FRIDAY. EXACT TIMING OF WHEN OUR UPPER LOW WILL EXIT THE PLAINS IS STILL SOMEWHAT UNCLEAR BUT FOLLOWING THE GFS/ECMWF TREND THE PCPN SHOULD BE TAPERING OFF IN OUR NE CWA FRIDAY MORNING WHILE CLOUDY SKIES REMAIN THROUGH EARLY SATURDAY. CLOUDS AND COLD NE/E WIND WILL BE KEEPING TEMPS ON THE COOL SIDE LATE WEEK. AT THIS TIME HAVE TRENDED TOWARDS THE COOLER GFS SOUNDING FOR TEMPS ON THURSDAY AND FRIDAY. THIS COLD AIR WILL BEGIN TO SLOWLY ERODE FROM SW TO NE EARLY THIS WEEKEND AS NW FLOW STARTS TO DEVELOP. TEMPERATURES WILL BEGIN TO REBOUND BACK INTO THE 60S BY SATURDAY AND IF THE GFS...ECWMF AND CANADIAN VERIFY THEN HIGHS BY MONDAY SHOULD BE IN THE 70S. .AVIATION... LOW LEVELS GRADUALLY SATURATE EARLY THIS EVENING WITH 925-85H AND 85H-7H FGEN FORCING PLACING THE BETTER CHANCE OF PCPN OVER DDC/HYS AROUND 6Z. THIS LOW LEVEL FORCING THEN SHIFTS EAST OF THE AREA BY 12Z. LOW LVL MOISTURE HOWEVER FROM BOTH THE NAM/GFS EXTENDS UP TO 85H LVL AT 12Z SO WILL TAKE SOME TIME FOR THIS DEPTH OF MOISTURE TO ERODE. HAVE THEREFORE FAVORED A SLOWER EROSION OF THE LOW CLOUDS THROUGH 18Z THAN WHAT THE GFS/LAMP GUIDANCE SUGGESTS. && .PRELIMINARY POINT TEMPS/POPS... DDC 36 52 31 54 / 60 30 0 50 GCK 33 51 30 53 / 60 20 0 40 EHA 34 60 34 54 / 20 20 0 30 LBL 36 58 31 54 / 30 20 0 40 HYS 34 47 31 53 / 60 40 0 50 P28 41 52 34 58 / 70 30 0 50 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN24/18 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1135 AM MDT SUN APR 6 2008 .UPDATE... 1110 AM MDT SUN APR 6 2008 JUST COMPLETED AN UPDATE. MAIN CHANGE WAS TO ISSUE A RED FLAG WARNING THROUGH 21Z THIS AFTERNOON. AIR MASS DRIER AND WINDIER THAN WHAT MODELS WERE SHOWING. DEWPOINTS HAVE TANKED TO SINGLE DIGITS TO NEAR ZERO OVER THE WESTERN PORTION OF THE FORECAST AREA. EXPECT THIS DRY AIR MASS TO SPREAD FURTHER EAST. WINDS ARE ALSO STRONGER AND DO NOT LOOK TO START DECREASING UNTIL THE EARLY TO MIDDLE AFTERNOON HOURS. USED REALITY AND THE NAM40 SOUNDINGS TO UPDATE DEWPOINTS. COMBINED REALITY WITH THE RUC13 FOR THE WIND FORECAST. ALSO ADJUSTED SKY GRIDS BASED ON CURRENT TRENDS AND SATELLITE. AT THIS TIME...THE HIGH TEMPERATURES LOOK IN THE BALLPARK. BULLER && .DISCUSSION... 224 AM MDT SUN APR 6 2008 RELATIVELY QUIET WX ON SUNDAY UNDER SHORTWAVE RIDGING. NORTHWEST SURFACE WINDS WILL GRADUALLY DIMINISH AS PRESSURE GRADIENT RELAXES BEHIND THE PACIFIC COLD FRONT. GAVE SOME THOUGHT TO POTENTIAL RED FLAG CONDITIONS WITH VERY LOW DEW POINTS ADVECTING FROM THE NORTHWEST...BUT WINDS FORECAST TO SUBSIDE BY THE TIME THE LOWEST RH ARRIVES THIS AFTERNOON...SO DECIDED AGAINST IT. SECONDARY CANADIAN COLD FRONT WILL BACKDOOR THE FORECAST AREA LATE TONIGHT. MODELS GENERATING SOME LIGHT QPF ALONG THE PALMER DIVIDE IN THE WESTERN CWA. POINT SOUNDINGS SHOW INVERTED-V PROFILES...AND THINK IT WILL BE VIRGA TONIGHT WITH LITTLE CHANCE OF MEASURABLE PRECIPITATION. HOWEVER...SYNOPTIC SCALE LIFT WILL BE ON THE INCREASE THROUGH THE DAY ON MONDAY WITH APPROACH OF SHORTWAVE TROUGH. NAM/GFS STILL TRYING TO CUT OFF A CIRCULATION AT 700MB OVER EXTREME NORTHEAST COLORADO BY 00Z TUESDAY. NAM SOUNDINGS RAPIDLY SATURATE...WHILE GFS NOT QUITE SO AGGRESSIVE. GIVEN LOW LEVEL UPSLOPE FLOW AND DYNAMICS ALOFT...LIKE THE WETTER SOLUTIONS. PHASE WILL BE A PROBLEM...AS ICE LIKELY TO DEVELOP IN DENDRITIC GROWTH ZONE...BUT SURFACE WET BULB TEMPERATURES WILL BE NEAR OR JUST ABOVE FREEZING. EVEN IF SNOW MAKES IT TO THE SURFACE...HARD TO GAUGE POTENTIAL FOR ACCUMULATION WITH WARM SOIL/GROUND TEMPERATURES TO START. USED A VERY LOW SLR OF 5 FOR MONDAY...TRANSITIONING TO 10 MONDAY NIGHT IN EXPECTATION OF A WET SNOW OF AN INCH OR TWO NORTH OF THE INTERSTATE. AN INTENSE CUT OFF LOW IS FORECAST TO MOVE ACROSS THE CENTRAL HIGH PLAINS WEDNESDAY AND THURSDAY. THE POSITION OF THE 500MB LOW OVER SOUTHERN AND CENTRAL KANSAS SUGGESTS THE LOCAL AREA WILL BE ON THE COLD SIDE UNDER POSSIBLE DEFORMATION SNOW BAND. STILL A BIT EARLY BUT ADDED A MENTION OF SNOW IN WESTERN HALF OF THE FORECAST AREA ON THURSDAY BASED PRIMARILY ON PATTERN RECOGNITION AND TIME OF YEAR. 24 && .AVIATION... 1134 AM MDT SUN APR 6 2008 FOR THE 18Z TAFS...VFR CONDITIONS WILL CONTINUE WITH AN INCREASE IN CLOUDS AFTER 00Z. CLOUDS WILL BEGIN TO LOWER TO 5K FT. AFTER 03Z BUT SHOULD REMAIN VFR THROUGH THE PERIOD. THE WIND SPEED WILL START TO DIMINISH AFTER 21Z AND REMAIN NORTHERLY, SURFACE HIGH PRESSURE WILL MAKE ITS WAY INTO THE REGION AND THE WINDS WILL EVENTUALLY TURN EAST/SOUTHEAST AROUND THE END OF THE TAF PERIOD. KJ && .GLD WATCHES/WARNINGS/ADVISORIES... KS...RED FLAG WARNING UNTIL 3 PM MDT /4 PM CDT/ THIS AFTERNOON FOR KSZ001>004-013>016-027>029. NE...RED FLAG WARNING UNTIL 3 PM MDT /4 PM CDT/ THIS AFTERNOON FOR NEZ079>081. CO...RED FLAG WARNING UNTIL 3 PM MDT THIS AFTERNOON FOR COZ252>254. && $$ WFO GOODLAND ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PADUCAH KY 839 PM CDT MON APR 7 2008 .UPDATE... INTERIM UPDATE FOR EVENING CLOUD/TEMPERATURE/DEWPOINT/WIND TRENDS. && .DISCUSSION... CLOUD TREND ACCOMODATED MORE EASILY WITH A SLIGHTLY SLOWER ONSET OF OPAQUE CIRRUS CLOUD DECK OVERNIGHT. WINDS ADJUSTED CLOSER TO A MORE SOUTHERLY ORIENTATION/SLOWER VEERING OF WINDS PER THE 13 KM RUC GUIDANCE THIS EVENING. TEMPERATURES AND DEWPOINTS REMAIN MORE PROBLEMATIC...AS ANTECEDENT CONVERGENCE/FRONTAL BOUNDARY STRETCHING FROM SIKESTON MO TO SACRAMENTO KY SHOWS A MARKED THETA-E BOUNDARY...WITH MIDDLE 30/LOWER 40 SURFACE DEWPOINTS TO THE NORTH AND UPPER 40/LOWER 50 DEWPOINTS TO THE SOUTH OF THE BOUNDARY. SOME ATTEMPT WAS MADE TO RECONCILE THE SUBTLE DIFFERENCES WITH SURROUNDING OFFICES. ANOTHER UPDATE OF THE TABULAR PRODUCTS MAY BE NECESSARY BEFORE LATE EVENING...IF SURFACE DEWPOINTS DO NOT REBOUND MUCH NORTH OF THE BOUNDARY. THE RUC/NAM...AND TO A SLIGHTLY LESSER DEGREE...THE SREF...HANDLE THE SYNOPTIC SITUATION WELL...WITH ONLY A MINOR VARIATIONS ON THE MASS/WIND/THERMAL FIELDS BY 12Z TUESDAY. && .PREV DISCUSSION... /ISSUED 320 PM CDT MON APR 7 2008/ DISCUSSION... CONCERN CONTINUES FOR HEAVY RAINFALL POTENTIAL WITH MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS FROM TUESDAY THROUGH FRIDAY AS TWO WEATHER SYSTEMS CROSS THE LOWER OHIO VALLEY. IN THE WAKE OF A WEAK SURFACE TROUGH PASSAGE TODAY...MOST AREAS WILL SEE A NORTH OR NORTHEASTERLY WIND BY 00Z. WINDS WILL THEN QUICKLY BECOME SOUTHEAST BY DAYBREAK TUESDAY...AS A WARM FRONT DEVELOPS TO THE NORTHWEST OF THE QUAD STATE. CAN SEE NO EVIDENCE TO SUPPORT A POP LATE TONIGHT...SO KEPT THE TONIGHT PERIOD DRY. ON TUESDAY AS THE NEXT STORM SYSTEM AND ASSOCIATED SFC LOW TRACK FROM THE SOUTHERN PLAINS TO THE GREAT LAKES...THE MAIN QUESTION WILL BE HOW QUICKLY DECENT LOW-LEVEL MOISTURE WILL MAKE IT BACK INTO THE AREA. LATEST MODELS SHOW SUFFICIENT MOISTURE RETURN TO SUPPORT DECCENT CONVECTION LATE TUESDAY AND ESPECIALLY TUESDAY NIGHT. HAVE LIKELY POPS IN THE WEST TUESDAY AFTERNOON...AND BUMPED THEM UP TO CATEGORICAL EVERYWHERE TUESDAY NIGHT. MODELS HAVE NOT BEEN THAT CONSISTENT WITH QPF PLACEMENT WITH EITHER OF THE TWO SYSTEMS THIS WEEK. MODELS ARE HINTING AT A FRONTAL WAVE DEVELOPING WEDNESDAY MORNING JUST SOUTHWEST OF OUR CWA WHICH WOULD SERVE TO HOLD BACK THE EASTWARD PROGRESS OF THE FRONT THUS KEEPING ANY BANDS OF HEAVY RAIN ASSOCIATED WITH THE BOUNDARY LINGERING LONGER ACROSS OUR CWA. WE WILL HAVE TO KEEP AN EYE ON THAT. GFS HAS SHOWN PROBLEMS WITH CONVECTIVE FEEDBACK...SO SOME OF ITS QPF OUTPUT HAS TO BE IGNORED. INITIAL THINKING OF TOTAL QPF WITH SYSTEM NUMBER ONE IS 1-2 INCHES. A SLIGHT RISK OF A FEW STORMS BECOMING SEVERE IS STILL A POSSIBILITY TUESDAY AND TUESDAY EVENING WITH LARGE HAIL AND DAMAGING WINDS BEING THE MAIN THREAT...ALTHOUGH PARAMETERS PALE IN COMPARISON TO SYSTEM NUMBER TWO COMING LATER THIS WEEK. SPEAKING OF SYSTEM NUMBER TWO...NOT LONG AFTER SYSTEM ONE CLEARS THE AREA...SYSTEM NUMBER TWO WILL BEGIN TO AFFECT THE REGION WEDNESDAY NIGHT. MODELS HAVE BEEN CONSISTENTLY SLOWING THE FORWARD PROGRESS OF THIS SYSTEM DUE TO INCREASED DEEPENING OF THE ASSOCIATED UPPER LOW. EARLIER RUNS SHOWED THE FRONT AND POTENTIAL FOR HEAVY RAIN MAINLY AFFECTING THE REGION ON THURSDAY...BUT THAT HAS NOW SHIFTED TO MORE OF A THURSDAY NIGHT SCENARIO. THE BULK OF PRECIP WILL BE CLEAR OF THE CWA BY MIDDAY FRIDAY...BUT UNFORTUNATELY THE POTENTIAL EXISTS FOR AN ADDITIONAL TWO TO THREE INCHES OF RAINFALL...WHICH WILL ONLY EXACERBATE THE FLOODING ISSUES WE ALREADY HAVE. TO MAKE MATTERS MORE INTERESTING HOWEVER IS THE POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER OUTBREAK THURSDAY INTO THURSDAY EVENING. NOT ENOUGH TIME TO DISCUSS IN DEPTH RIGHT NOW...BUT NUMEROUS SEVERE WEATHER PARAMETERS WILL BE IN PLACE FOR A SIGNIFICANT WEATHER EVENT WITH A HIGH PROBABILITY OF LARGE HAIL...DAMAGING WINDS...AND SUPERCELL THUNDERSTORMS CAPABLE OF PRODUCING LONG TRACK TORNADOES. A SMALL CHANCE FOR LIGHT PRECIP IN THE WRAP AROUND MOISTURE EXISTS FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE THEN KEEPS THE REGION DRY AND COOLER THROUGH THE END OF THE SEVEN DAY FORECAST PERIOD. WILL BE ISSUING AN ESF (HYDROLOGIC OUTLOOK) SHORTLY FOR THE FLOOD POTENTIAL FROM TUESDAY NIGHT THROUGH THURSDAY NIGHT. AVIATION... VFR CONDITIONS WILL CONTINUE INTO TONIGHT...WITH HIGH CLOUDS INCREASING TO BKN THEN OVC BY 12Z. LIGHT NORTHWEST TO NORTH WINDS WILL GRADUALLY TURN NORTHEAST THEN SOUTH OVERNIGHT. WINDS AFTER 12Z WILL THEN INCREASE FROM THE SOUTH TO SOUTHWEST TO AROUND 10 KTS. NO RESTRICTIONS TO VSBYS EXPECTED. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ SHORT TERM/LONG TERM/AVIATION...SMITH ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1028 PM CDT MON APR 7 2008 .DISCUSSION...TOUGH CALL ON DEGREE OF FOG TONIGHT WITH THE MAIN CON BEING THE LLJ FORECAST TO DEVELOP OVER ERN TX/WRN LA. KLCH AND KPOE VAD WIND PROFILES BOTH SHOWING 25-30KT AT 1K FT...WHICH IS FAIRLY CLOSE TO PROGS AT 975MB SHOWN BY THE GFS AND NAM. MEANWHILE...FORECAST SOUNDINGS/TIME HEIGHTS CONTINUE TO SHOW LL MOISTURE TRAPPED BENEATH THE NOCTURNAL INVERSION. IN ADDITION...RAW PROGS SHOWN BY THE RUC/NAM/SREF ALL POINT TO A DECENT CHANCE OF VISIBILITY FALLING BELOW AT LEAST 1SM....WHILE NUMERICAL GUIDANCE POINTS TO FOG KLCH EASTWARD TO KLFT. IN THE FACE OF THIS UNCERTAINTY...WILL NOT BE ISSUING AN ADVISORY AT THIS TIME... AND SIMPLY ADJUST BUT OTHERWISE MAINTAIN INHERITED PATCHY/AREAS WORDING. ALSO ADJUSTED SKY COVER AS THE BETTER STRATUS SIGNAL IS TO OUR WEST...AND CIRRUS FROM CONVECTION OVER OK AND N TX SHOULD REMAIN TO OUR NORTH. FOR THE EVENING COASTAL WATERS ISSUANCE...WINDS CURRENTLY NEAR SCEC CRITERIA...THOUGH THEY ARE EXPECTED TO WEAKEN LATER TONIGHT. KEPT THE CWF HEADLINE FREE. && .PREV DISCUSSION... /ISSUED 306 PM CDT MON APR 7 2008/ SYNOPSIS...A DRY ZONAL FLOW DOMINATES THE LOWER 48. WHILE MINOR DISTURBANCES ARE EMBEDDED IN THE WESTERLY UPPER FLOW, THERE IS VERY LITTLE MOISTURE AVAILABLE TO LIFT AND CAPPING DOMINATES THE LOWER ATMOSPHERE. FOG IS ANOTHER ISSUE. LEFT OVER MOISTURE NEAR THE SURFACE WITH LIGHT WINDS AND CLEAR SKIES WILL ALLOW FOR ANOTHER NIGHT WITH AREAS OF FOG OVER MOST OF THE AREA. WOULD NOT BE SURPRISED IF ANOTHER DENSE FOG ADVISORY ENDED UP BEING REQUIRED. SINCE FOG FORMATION WILL BE BEYOND THE EVENING HOURS, WILL LET THE NIGHT CREWS TAKE ANOTHER LOOK AT THAT. SHORT TERM...STRONG FOG SIGNAL AND PERSISTENCE ANOTHER NIGHT OF LATE FOG. NGM HAS BEEN VERIFYING WELL ON POPS AND ZEROS WILL RULE INTO TUESDAY. CAPPING AND A SUBSIDENT RIGHT FRONT QUAD OF THE H3 JET SHOULD GIVE AN ASSIST TO THE GOAL OF KEEPING PRECIP OUT OF THE FCST ON TUESDAY. GFS HAS BEEN TOUGH TO BEAT ON TEMPS. HUGGED THAT GUIDANCE TIGHTLY. LONG TERM...A PACIFIC COLD FRONT WILL PROVIDE OUR NEXT CHANCE OF RAIN ON WEDNESDAY. WE FIND OURSELVES WITHIN A BROAD AREA OF SLIGHT RISK FOR SEVERE TSTMS. BETTER DYNAMICS APPEAR WELL TO THE NORTH. LOW LEVEL JET NOT ALL THAT STRONG AT 20 KTS. CAPES AROUND 1500 JOULES COULD SUPPORT SOME HAIL BUT ALL IN ALL LOOKS TO BE A STRETCH. WEEKEND LOOKING COOL AND DRY IN THE WAKE OF THE COLD FRONT. AVIATION...LIFR FOG LATE TNITE. MARINE...BACKED OFF ON THE INCREASING SOUTHERLY WINDS LATE TUESDAY AS LATEST SHORT RANGE MODELS SHOW LESS PRESSURE FALLS IN THE SOUTHERN PLAINS OVER THE NEXT 24 HOURS. SOUTHERLY WINDS STILL LOOK TO INCREASE BY THURSDAY TO SCEC OR POSSIBLY SCA CRITERIA AS THE NEXT LOW PRESSURE SYSTEM DEEPENS OVER THE SOUTHERN PLAINS. DELAYED STRONG NORTHERLY WINDS UNTIL A MID LEVEL TROF APPROACHES LATE FRIDAY NIGHT. && .PRELIMINARY POINT TEMPS/POPS... KLCH 64 82 71 82 / 0 0 10 30 KBPT 66 81 71 83 / 0 0 10 30 KAEX 56 85 66 83 / 0 0 10 30 KLFT 61 83 69 81 / 0 0 10 40 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$ 13 la AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1147AM EDT MON APR 7 2008 UPDATED AVIATION SECTION .SHORT TERM...THIS AFTERNOON AND TONIGHT. WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER WEST CENTRAL WISCONSIN. MODELS SHOWING THAT THIS LOW WILL TRACK NORTHEAST INTO SOUTH CENTRAL U.P. THIS AFTERNOON. MEANWHILE...THE ACCOMPANYING SURFACE LOW WILL TRACK FROM NORTHEAST WISCONSIN INTO CENTRAL UPPER MICHIGAN DRAGGING A COLD FRONT INTO EASTERN LOWER MICHIGAN. LOW LEVEL MOISTURE CONTINUES TO BE DRAWN INTO THE AREA AHEAD OF THE FRONTAL SYSTEM. ISENTROPIC ASENT NORTH OF THE LOW AND SHORTWAVE ENERGY WILL CONTINUE TO GENERATE RAIN ACROSS THE AREA. A WEAK DRY SLOT WILL SWEEP THROUGH THE U.P. WITH THE LOW. SO THERE WILL BE A BRIEF LET UP BEFORE THE WRAP AROUND RAINS SHIFT OVER THE AREA. COOLER TEMPERATURES WILL ADVECT INTO THE WEST END OF THE FORECAST AREA. THE CURRENT GRIDS REFLECT THIS ALREADY. WARM AIR ADVECTION WRAPPING AROUND THE LOW WILL PUSH THE TEMPERATURES UP TO AROUND 50 THIS AFTERNOON. THE LOW WILL MOVE TO NORTHEAST ONTARIO TONIGHT. AS IT LIFTS NORTHEAST IT WILL LOSE ITS LOW AND MID LEVEL SUPPORT AND DRY AIR WILL ADVECT INTO THE AREA CAUSING THE RAIN/SNOW TO END. TRAJECTORY FORECAST SUGGEST AIR MASS OVER WESTERN ONTARIO WILL SLIDE INTO THE AREA TONIGHT. THIS WOULD SUPPORT OVERNIGHT LOW TEMPERATURES LOWERING TO ONLY THE UPPER 20S ACROSS THE AREA. .LONG TERM...TUESDAY AND LATER. WEAK HI PRES RDG EXTENDING SWD FM CENTER OVER HUDSON BAY WL BE IN CONTROL ON TUE MRNG AND BRING DRY WX INTO THE AFTN...BUT FOCUS IN THE AFTN WL SHIFT TO THE SCNTRL PLAINS...WHERE SFC LO PRES WL BE DVLPG IN ASSOCIATION WITH ARRIVAL OF SHRTWV NOW MOVING INTO THE PAC NW. OVERALL...NCEP PREFERS THE 12Z ECMWF FOR THE HANDLING OF THIS LO...WITH THE TIMING A BIT SLOWER THAN EXPLICITLY FCST BY THIS MODEL. THE 12Z ECMWF SHOWS THE SFC LO REACHING NCNTRL IL BY 00Z WED... BUT A SLOWER VERSION WOULD LINE UP NICELY WITH THE NAM/GFS FCST POSITION IN SCNTRL IL IN ADVANCE OF NEGATIVELY TILTED SHRTWV LIFTING OUT OF THE MEAN WRN TROF. EXPECT HI CLD TO BE ON THE INCRS ON TUE IN THE INCRSGLY DIFFLUENT UPR FLOW WITH THE CLD BASE GRDLY LOWERING WITH INCRSG ISENTROPIC LIFT SHOWN ON THE 290-300K SFCS. SINCE NCEP PREFERS A SLOWER TIMING AND GFS FCST SDNGS SHOW QUITE A BIT OF MID LVL DRY AIR OVER THE SCNTRL THRU 00Z WED...OPTED TO SLOW ARRIVAL OF PCPN FM THE S A FEW HRS A BIT IN LINE WITH GFS MOS GUIDANCE. OVERALL...THE 12Z ECMWF TRACK SHOWING THE LO MOVING INTO THE ERN U.P. IS A COMPROMISE BTWN THE DEEPER/FARTHER W SOLN OF THE NAM AND THE SOMEWHAT WEAKER/FARTHER E TRACK SHOWN BY THE GFS. COMPROMISE BTWN THESE TWO SCENARIOS WOULD SUG A RA/SN LINE FM P53 TO JUST SE OF IMT USING H925-85 CRITICAL THKNS OF 676M. FCST SDNGS FM BOTH MODELS SUG PCPN WL BE EITHER RA OR SN...WITH NO ELEVATED WARM LYR ABV A SUB FRZG LYR OF SGIFNICANCE TO CAUSE FZRA/PL THAT WOULD BE MORE TYPICAL OF A MID WINTER SYS. AS FAR AS PCPN AMTS ARE CONCERNED...THE GFS AND ESPECIALLY THE NAM BOTH SHOW SHARP H8-7 FGEN ON THE WRN FLANK OF THE H7 LO TRACK (NAM PLACEMENT IS A BIT FARTHER W...GFS TO THE E). WITH 4 G/KG SPECIFIC HUMIDITY AVBL AND A 12HR PD OF UVV...SN AMTS OF 8"/12 HRS WOULD BE PSBL UNDER THIS SHARPEST DEFORMATION ZN. ATLHOUGH SN/WATER RATIOS WL LIKELY BE LO (10:1) WITH RATHER NARROW DGZ SHOWN ON BUFKIT SDNGS...HVY/WET NATURE OF THE SN AND LOWER WRNG CRITERIA (6"/12HRS) FOR THE WI BORDER COUNTIES SEEMS TO JUSTIFY A WATCH THERE...ESPECIALLY SINCE BULK OF SN WL FALL DURING THE NGT WHEN HTG OF THE LLVLS WL BE ABSENT. ALSO DECIDED TO ISSUE A WATCH FOR MQT COUNTY WITH POTENTIAL FOR SOME UPSLOPE ENHANCEMENT OF THE PCPN WITH FAIRLY TIGHT NNE FLOW PERPENDICULAR TO THE TERRAIN CONTOURS. QUICK LOOK AT THE 00Z ECMWF SEEMS TO JUSTIFY WATCH ISSUANCE WITH CLASSIC COMMA HEAD HIER RH PATTERN ON THE CYC SIDE OF H7 LO/H5 VORT TRACK THRU THE UPR LKS. COORDINATED WITH GRB/DLH/APX/LOT. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... COLD POOL ALOFT HAS ALLOWED FOR SHOWERS AND EVEN A FEW LIGHTNING STRIKES ACROSS UPPER MICHIGAN. THE LIGHTNING SHOULD AVOID THE TERMINALS...HOWEVER A CB HAS BEEN NOTED AT KSAW BTWN 18-20Z DUE TO THE PROXIMITY OF 18-20KFT SHOWERS/STORMS ACROSS WESTERN MQT COUNTY. THE LOW OVER NRN WI WILL MOVE INTO LAKE SUPERIOR BY THIS EVENING. THIS SHOULD ALLOW VSBYS TO IMPROVE DURING THE DAY AS SLIGHTLY DRIER AIR MOVES INTO THE REGION BEHIND THE LOW. HOWEVER...THE LOWER LOW MVFR TO IFR CLOUDS SHOULD CONTINUE THROUGH THE AFTERNOON AND OVERNIGHT AS LOW LEVEL MOISTURE REMAINS PLENTIFUL. WILL NEED TO WATCH FOR SOME UPSLOPE DRIZZLE OR PERHAPS FZDZ OVERNIGHT. AS ADDITIONAL DRY AIR MOVES INTO THE UPPER LAKES TUE MORNING...CIGS/VSBYS SHOULD RISE TO MVFR ALL SITES BY 14Z. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRES WILL MOVE NORTHEASTWARD ACROSS THE AREA...AND INTO ONTARIO LATE THIS EVENING. 20 TO 30 KT GUSTS WILL DIMINISH AS THE LOW MOVES OVERHEAD...AND HIGH PRESSURE BEGINS TO FILTER IN THIS EVENING. THE NEXT PERIOD OF POTENTIAL GALES LOOKS TO BE LATE TUESDAY NIGHT INTO WEDNESDAY...AS A SFC LOW SLIDES UP FROM THE SOUTHWEST. THE TRACK SHOULD BRING IT OVER FAR EASTERN LS TO LH BY WEDNESDAY MORNING. KEEPING JUST BELOW GALES AT THE MOMENT...BUT WOULD NOT BE SURPRISED IF GALES WILL BE NEEDED. TOWARDS THE END OF THE PERIOD...YET ANOTHER SFC LOW SLIDES NORTHEASTWARD TOWARDS LM FRIDAY. AT THIS TIME THIS LAST LOW SEEMS TO BE THE STRONGEST...WITH THE BEST CHANCE FOR LS WIDE GALES FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ005-010-011. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && && $$ SHORT TERM...DLG LONG TERM...KC AVIATION...MRD MARINE...KF mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 728 AM EDT MON APR 7 2008 UPDATED FOR 12Z TAF ISSUANCE .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW GENERAL WRN TROFFING AND ERN RDGING OVR THE CONUS. NEGATIVELY TILTED SHRTWV IS MOVING THRU SRN MN EARLY THIS MRNG...WITH SFC LO NOT FAR FM MPX. QUITE A BIT OF MID/HI CLD HAS OVERSPRD THE FA...BUT WARM CONVEYOR BELT PCPN IN THE FORM OF RA IS CONFINED TO THE WRN COUNTIES AS 00Z APX/GRB RAOBS SHOW EXTREMELY DRY AIR BLO THE MID/HI LVL MSTR (H7 DWPT DEPRESSION AT APX IS 32C...H85 DWPT DEPRESSION AT GRB IS 27C). AXIS OF MAIN BAND OF WARM CONVEYOR BELT PCPN EXTENDS FM NW WI SSE INTO SCNTRL WI. THE ERN EDGE OF THIS PCPN IS MOVING EWD ONLY SLOWLY INTO THE DRY AIR DESPITE WHAT APPEARS ON WV IMAGERY TO BE A FAIRLY STEADY EWD PROGRESSION OF THE SHRTWV THRU SRN MN. THE PROBLEM APPEARS TO BE THE SSE LLVL FLOW E OF THE PCPN AXIS THAT IS PROVIDING A CONTINUOUS FEED OF THE DRY AIR SHOWN ON THE GRB/APX SDNGS AS WELL AS A LACK OF ANY GLFMEX MSTR FEED AT H85. WELL DEFINED DRY SLOTTING IS MOVING INTO WRN WI BEHIND THE WARM CONVEYOR BELT RA. MUCH HEAVIER WINTRY PCPN IS CURRENTLY FALLING IN THE DEFORMATION ZN/COMMA HEAD ON THE CYC COLD SIDE OF THE SHRTWV/SFC LO TRACK FM NRN MN INTO THE ERN DAKOTAS. MUCH DRIER AIR IS OBSVD FARTHER W IN THE DAKOTAS (00Z H85 DWPT DEPRESSION IS 21C AT BIS WITH SFC DWPTS AOB 0F THERE). NEXT SHRTWV OF CONCERN IS NOW MOVING ONSHORE IN THE PAC NW. MAIN FCST CONCERNS IN THE SHORT TERM ARE RA CHCS THRU TDAY AND POTENTIAL FOR ANY WINTRY PCPN LATER TDAY/THIS EVNG. FOCUS FOR TUE/WED TURNS TO TIMING/IMPACT OF SHRTWV NOW MOVING INTO THE PAC NW. FOR TDAY...INCSRGLY OCCLUDED LO IS FCST TO MOVE OVER SCNTRL LK SUP BY 00Z TUE. 00Z NAM APPEARS TO HAVE GOOD HANDLE ON THE EVOLUTION OF WARM CONVEYOR BELT PCPN SHOWING INCRSGLY NARROW WARM CONVEYOR BELT SHRA PINCHED OFF BY DRY SLOTTING FM THE W AND EVAPORATION OF PCPN MOVING INTO THE BONE DRY AIR TO THE E IN THE ABSENCE OF ANY GLFMEX MSTR FEED. IN FACT...MODEL APPEARS TO DEGENERATE MAIN BODY OF RA INTO JUST SOME SCT SHRA BY THE TIME WHAT IS LEFT OF THE WARM CONVEYOR BELT REACHES ERY LATE IN THE MRNG. FCST WL REFLECT DIMINISHING POPS TO THE E. IN LGT OF THESE EXPECTATIONS AND WITH ABSENCE OF ANY LGT STRIKES DURING THE NGT...REMOVED MENTION OF TS FM THE DECAYING WARM CONVEYOR BELT. ARRIVAL OF DRY SLOT WL THEN END PCPN CHCS FOR AT LEAST A SHORT TIME. HOWEVER... ARRIVAL OF SHRTWV/COLD POCKET ALF AS WELL AS AN AREA OF DEEPER MSTR WL BRING A RETURN OF MORE SHRA CHCS WITH STEEPENING LAPSE RATES ENHANCED BY ANY SFC HTG IN THE DRY SLOT. MODIFIED NAM F18 SDNG FOR 53/39 YIELDS ONLY 135 J/KG...SO EVEN THOUGH SITUATION MIGHT SEEM FVRBL FOR TS DOUBT THERE WL BE STRG CNVCTN. PLUS NO TS OBSVD UPSTREAM YDAY AFTN UNDER DRY SLOT. OTRW...WL GO WITH THE HIER POPS UP TO HI CHC ON THE CYC SIDE OF THE SHRTWV TRACK. NEW NAM FCST INDICATES THE AIRMASS WL BCM COLD ENUF FOR SN TO MIX WITH THE PCPN ONLY LATE OVER THE W AS SOME COLD LLVL AIR FINALLY ARRIVES IN THE CYC NW FLOW IN THE WAKE OF THE LO MOVING TO THE NE. AS STACKED LO PULLS TO THE NE TNGT AND GIVES WAY TO RISING HGTS/ DNVA/MID LVL DRYING...EXPECT ANY LINGERING SHRASN TO DIMINISH WITH LOSS OF DIURNAL HTG. GFS/NAM FCST SDNGS HINT AT LINGERING LLVL MSTR HANGING IN OVER THE W WITH CYC NNW FLOW/TRAJECTORIES FM THE N PREVENTING INFLUX OF VERY DRY AIR NOW IN THE NRN PLAINS. SO EXPECT LO CLD TO LINGER ESPECIALLY IN UPSLOPE AREAS NEAR LK SUP WITH RELATIVELY SHALLOW INFLUX OF COLD AIR STRENGTHENING INVRN. HOWEVER...SFC AIR OVER NW ONTARIO TO THE N OF PCPN SHIELD IS ALSO QUITE DRY...SO NUMERICAL MODELS SEEM TO HANG ON TO NR SFC MSTR TOO LONG...A TYPICAL BIAS OF LATE. BEST CHC FOR CLRG WL BE OVER THE SCNTRL ZNS WHERE FLOW WL BE DOWNSLOPING. MOS FCST LO TEMPS ARE QUITE SIMILAR...BUT WL SHAVE OFF A DEGREE OR TWO TO ACCOUNT FOR RELATIVELY HI STABILITY/SHALLOW NATURE OF COLD AIR INFLUX. WEAK HI PRES RDG EXTENDING SWD FM CENTER OVER HUDSON BAY WL BE IN CONTROL ON TUE MRNG AND BRING DRY WX INTO THE AFTN...BUT FOCUS IN THE AFTN WL SHIFT TO THE SCNTRL PLAINS...WHERE SFC LO PRES WL BE DVLPG IN ASSOCIATION WITH ARRIVAL OF SHRTWV NOW MOVING INTO THE PAC NW. OVERALL...NCEP PREFERS THE 12Z ECMWF FOR THE HANDLING OF THIS LO...WITH THE TIMING A BIT SLOWER THAN EXPLICITLY FCST BY THIS MODEL. THE 12Z ECMWF SHOWS THE SFC LO REACHING NCNTRL IL BY 00Z WED... BUT A SLOWER VERSION WOULD LINE UP NICELY WITH THE NAM/GFS FCST POSITION IN SCNTRL IL IN ADVANCE OF NEGATIVELY TILTED SHRTWV LIFTING OUT OF THE MEAN WRN TROF. EXPECT HI CLD TO BE ON THE INCRS ON TUE IN THE INCRSGLY DIFFLUENT UPR FLOW WITH THE CLD BASE GRDLY LOWERING WITH INCRSG ISENTROPIC LIFT SHOWN ON THE 290-300K SFCS. SINCE NCEP PREFERS A SLOWER TIMING AND GFS FCST SDNGS SHOW QUITE A BIT OF MID LVL DRY AIR OVER THE SCNTRL THRU 00Z WED...OPTED TO SLOW ARRIVAL OF PCPN FM THE S A FEW HRS A BIT IN LINE WITH GFS MOS GUIDANCE. OVERALL...THE 12Z ECMWF TRACK SHOWING THE LO MOVING INTO THE ERN U.P. IS A COMPROMISE BTWN THE DEEPER/FARTHER W SOLN OF THE NAM AND THE SOMEWHAT WEAKER/FARTHER E TRACK SHOWN BY THE GFS. COMPROMISE BTWN THESE TWO SCENARIOS WOULD SUG A RA/SN LINE FM P53 TO JUST SE OF IMT USING H925-85 CRITICAL THKNS OF 676M. FCST SDNGS FM BOTH MODELS SUG PCPN WL BE EITHER RA OR SN...WITH NO ELEVATED WARM LYR ABV A SUB FRZG LYR OF SGIFNICANCE TO CAUSE FZRA/PL THAT WOULD BE MORE TYPICAL OF A MID WINTER SYS. AS FAR AS PCPN AMTS ARE CONCERNED...THE GFS AND ESPECIALLY THE NAM BOTH SHOW SHARP H8-7 FGEN ON THE WRN FLANK OF THE H7 LO TRACK (NAM PLACEMENT IS A BIT FARTHER W...GFS TO THE E). WITH 4 G/KG SPECIFIC HUMIDITY AVBL AND A 12HR PD OF UVV...SN AMTS OF 8"/12 HRS WOULD BE PSBL UNDER THIS SHARPEST DEFORMATION ZN. ATLHOUGH SN/WATER RATIOS WL LIKELY BE LO (10:1) WITH RATHER NARROW DGZ SHOWN ON BUFKIT SDNGS...HVY/WET NATURE OF THE SN AND LOWER WRNG CRITERIA (6"/12HRS) FOR THE WI BORDER COUNTIES SEEMS TO JUSTIFY A WATCH THERE...ESPECIALLY SINCE BULK OF SN WL FALL DURING THE NGT WHEN HTG OF THE LLVLS WL BE ABSENT. ALSO DECIDED TO ISSUE A WATCH FOR MQT COUNTY WITH POTENTIAL FOR SOME UPSLOPE ENHANCEMENT OF THE PCPN WITH FAIRLY TIGHT NNE FLOW PERPENDICULAR TO THE TERRAIN CONTOURS. QUICK LOOK AT THE 00Z ECMWF SEEMS TO JUSTIFY WATCH ISSUANCE WITH CLASSIC COMMA HEAD HIER RH PATTERN ON THE CYC SIDE OF H7 LO/H5 VORT TRACK THRU THE UPR LKS. COORDINATED WITH GRB/DLH/APX/LOT. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... RAIN WILL CONTINUE TO SLIDE NORTHWARD THROUGH MID MORNING AT SAW. CENTER OF CIRCULATION SHOWED UP WELL ON IR SATELLITE IMG OVER SE MN AT 11Z. THIS LOW WILL SHIFT OVER US THIS AFTERNOON. SOME DRY AIR HAS BEEN WORKING INTO EASTERN WI...BUT IT LOOKS LIKE ANY BREAK IN THE OVC WILL BE SHORT LIVED. WILL KEEP BKN-OVC THROUGH THE ENTIRE PERIOD...MAINLY LIFT TO IFR CEIGS AND VIS. CIGS AND VSBYS WILL IMPROVE IN THE AFTERNOON AS THE MAIN SYSTEM SLIDES OVERHEAD. STILL...SOME SHOWERS COULD STILL POP UP THIS AFTERNOON. MELTING SNOW...ALONG WITH WHAT FELL THIS MORNING WILL ADD TO THE LOW LEVEL MOISTURE AND KEEP THE LOWER CLOUDS LOCKED IN A BIT LONGER ACROSS UPPER MICHIGAN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRES WILL MOVE NORTHEASTWARD ACROSS THE AREA...AND INTO ONTARIO LATE THIS EVENING. 20 TO 30 KT GUSTS WILL DIMINISH AS THE LOW MOVES OVERHEAD...AND HIGH PRESSURE BEGINS TO FILTER IN THIS EVENING. THE NEXT PERIOD OF POTENTIAL GALES LOOKS TO BE LATE TUESDAY NIGHT INTO WEDNESDAY...AS A SFC LOW SLIDES UP FROM THE SOUTHWEST. THE TRACK SHOULD BRING IT OVER FAR EASTERN LS TO LH BY WEDNESDAY MORNING. KEEPING JUST BELOW GALES AT THE MOMENT...BUT WOULD NOT BE SURPRISED IF GALES WILL BE NEEDED. TOWARDS THE END OF THE PERIOD...YET ANOTHER SFC LOW SLIDES NORTHEASTWARD TOWARDS LM FRIDAY. AT THIS TIME THIS LAST LOW SEEMS TO BE THE STRONGEST...WITH THE BEST CHANCE FOR LS WIDE GALES FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ005. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && && $$ DISCUSSION...KC AVIATION...AJ/KF MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 427 AM EDT MON APR 7 2008 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW GENERAL WRN TROFFING AND ERN RDGING OVR THE CONUS. NEGATIVELY TILTED SHRTWV IS MOVING THRU SRN MN EARLY THIS MRNG...WITH SFC LO NOT FAR FM MPX. QUITE A BIT OF MID/HI CLD HAS OVERSPRD THE FA...BUT WARM CONVEYOR BELT PCPN IN THE FORM OF RA IS CONFINED TO THE WRN COUNTIES AS 00Z APX/GRB RAOBS SHOW EXTREMELY DRY AIR BLO THE MID/HI LVL MSTR (H7 DWPT DEPRESSION AT APX IS 32C...H85 DWPT DEPRESSION AT GRB IS 27C). AXIS OF MAIN BAND OF WARM CONVEYOR BELT PCPN EXTENDS FM NW WI SSE INTO SCNTRL WI. THE ERN EDGE OF THIS PCPN IS MOVING EWD ONLY SLOWLY INTO THE DRY AIR DESPITE WHAT APPEARS ON WV IMAGERY TO BE A FAIRLY STEADY EWD PROGRESSION OF THE SHRTWV THRU SRN MN. THE PROBLEM APPEARS TO BE THE SSE LLVL FLOW E OF THE PCPN AXIS THAT IS PROVIDING A CONTINUOUS FEED OF THE DRY AIR SHOWN ON THE GRB/APX SDNGS AS WELL AS A LACK OF ANY GLFMEX MSTR FEED AT H85. WELL DEFINED DRY SLOTTING IS MOVING INTO WRN WI BEHIND THE WARM CONVEYOR BELT RA. MUCH HEAVIER WINTRY PCPN IS CURRENTLY FALLING IN THE DEFORMATION ZN/COMMA HEAD ON THE CYC COLD SIDE OF THE SHRTWV/SFC LO TRACK FM NRN MN INTO THE ERN DAKOTAS. MUCH DRIER AIR IS OBSVD FARTHER W IN THE DAKOTAS (00Z H85 DWPT DEPRESSION IS 21C AT BIS WITH SFC DWPTS AOB 0F THERE). NEXT SHRTWV OF CONCERN IS NOW MOVING ONSHORE IN THE PAC NW. MAIN FCST CONCERNS IN THE SHORT TERM ARE RA CHCS THRU TDAY AND POTENTIAL FOR ANY WINTRY PCPN LATER TDAY/THIS EVNG. FOCUS FOR TUE/WED TURNS TO TIMING/IMPACT OF SHRTWV NOW MOVING INTO THE PAC NW. FOR TDAY...INCSRGLY OCCLUDED LO IS FCST TO MOVE OVER SCNTRL LK SUP BY 00Z TUE. 00Z NAM APPEARS TO HAVE GOOD HANDLE ON THE EVOLUTION OF WARM CONVEYOR BELT PCPN SHOWING INCRSGLY NARROW WARM CONVEYOR BELT SHRA PINCHED OFF BY DRY SLOTTING FM THE W AND EVAPORATION OF PCPN MOVING INTO THE BONE DRY AIR TO THE E IN THE ABSENCE OF ANY GLFMEX MSTR FEED. IN FACT...MODEL APPEARS TO DEGENERATE MAIN BODY OF RA INTO JUST SOME SCT SHRA BY THE TIME WHAT IS LEFT OF THE WARM CONVEYOR BELT REACHES ERY LATE IN THE MRNG. FCST WL REFLECT DIMINISHING POPS TO THE E. IN LGT OF THESE EXPECTATIONS AND WITH ABSENCE OF ANY LGT STRIKES DURING THE NGT...REMOVED MENTION OF TS FM THE DECAYING WARM CONVEYOR BELT. ARRIVAL OF DRY SLOT WL THEN END PCPN CHCS FOR AT LEAST A SHORT TIME. HOWEVER... ARRIVAL OF SHRTWV/COLD POCKET ALF AS WELL AS AN AREA OF DEEPER MSTR WL BRING A RETURN OF MORE SHRA CHCS WITH STEEPENING LAPSE RATES ENHANCED BY ANY SFC HTG IN THE DRY SLOT. MODIFIED NAM F18 SDNG FOR 53/39 YIELDS ONLY 135 J/KG...SO EVEN THOUGH SITUATION MIGHT SEEM FVRBL FOR TS DOUBT THERE WL BE STRG CNVCTN. PLUS NO TS OBSVD UPSTREAM YDAY AFTN UNDER DRY SLOT. OTRW...WL GO WITH THE HIER POPS UP TO HI CHC ON THE CYC SIDE OF THE SHRTWV TRACK. NEW NAM FCST INDICATES THE AIRMASS WL BCM COLD ENUF FOR SN TO MIX WITH THE PCPN ONLY LATE OVER THE W AS SOME COLD LLVL AIR FINALLY ARRIVES IN THE CYC NW FLOW IN THE WAKE OF THE LO MOVING TO THE NE. AS STACKED LO PULLS TO THE NE TNGT AND GIVES WAY TO RISING HGTS/ DNVA/MID LVL DRYING...EXPECT ANY LINGERING SHRASN TO DIMINISH WITH LOSS OF DIURNAL HTG. GFS/NAM FCST SDNGS HINT AT LINGERING LLVL MSTR HANGING IN OVER THE W WITH CYC NNW FLOW/TRAJECTORIES FM THE N PREVENTING INFLUX OF VERY DRY AIR NOW IN THE NRN PLAINS. SO EXPECT LO CLD TO LINGER ESPECIALLY IN UPSLOPE AREAS NEAR LK SUP WITH RELATIVELY SHALLOW INFLUX OF COLD AIR STRENGTHENING INVRN. HOWEVER...SFC AIR OVER NW ONTARIO TO THE N OF PCPN SHIELD IS ALSO QUITE DRY...SO NUMERICAL MODELS SEEM TO HANG ON TO NR SFC MSTR TOO LONG...A TYPICAL BIAS OF LATE. BEST CHC FOR CLRG WL BE OVER THE SCNTRL ZNS WHERE FLOW WL BE DOWNSLOPING. MOS FCST LO TEMPS ARE QUITE SIMILAR...BUT WL SHAVE OFF A DEGREE OR TWO TO ACCOUNT FOR RELATIVELY HI STABILITY/SHALLOW NATURE OF COLD AIR INFLUX. WEAK HI PRES RDG EXTENDING SWD FM CENTER OVER HUDSON BAY WL BE IN CONTROL ON TUE MRNG AND BRING DRY WX INTO THE AFTN...BUT FOCUS IN THE AFTN WL SHIFT TO THE SCNTRL PLAINS...WHERE SFC LO PRES WL BE DVLPG IN ASSOCIATION WITH ARRIVAL OF SHRTWV NOW MOVING INTO THE PAC NW. OVERALL...NCEP PREFERS THE 12Z ECMWF FOR THE HANDLING OF THIS LO...WITH THE TIMING A BIT SLOWER THAN EXPLICITLY FCST BY THIS MODEL. THE 12Z ECMWF SHOWS THE SFC LO REACHING NCNTRL IL BY 00Z WED... BUT A SLOWER VERSION WOULD LINE UP NICELY WITH THE NAM/GFS FCST POSITION IN SCNTRL IL IN ADVANCE OF NEGATIVELY TILTED SHRTWV LIFTING OUT OF THE MEAN WRN TROF. EXPECT HI CLD TO BE ON THE INCRS ON TUE IN THE INCRSGLY DIFFLUENT UPR FLOW WITH THE CLD BASE GRDLY LOWERING WITH INCRSG ISENTROPIC LIFT SHOWN ON THE 290-300K SFCS. SINCE NCEP PREFERS A SLOWER TIMING AND GFS FCST SDNGS SHOW QUITE A BIT OF MID LVL DRY AIR OVER THE SCNTRL THRU 00Z WED...OPTED TO SLOW ARRIVAL OF PCPN FM THE S A FEW HRS A BIT IN LINE WITH GFS MOS GUIDANCE. OVERALL...THE 12Z ECMWF TRACK SHOWING THE LO MOVING INTO THE ERN U.P. IS A COMPROMISE BTWN THE DEEPER/FARTHER W SOLN OF THE NAM AND THE SOMEWHAT WEAKER/FARTHER E TRACK SHOWN BY THE GFS. COMPROMISE BTWN THESE TWO SCENARIOS WOULD SUG A RA/SN LINE FM P53 TO JUST SE OF IMT USING H925-85 CRITICAL THKNS OF 676M. FCST SDNGS FM BOTH MODELS SUG PCPN WL BE EITHER RA OR SN...WITH NO ELEVATED WARM LYR ABV A SUB FRZG LYR OF SGIFNICANCE TO CAUSE FZRA/PL THAT WOULD BE MORE TYPICAL OF A MID WINTER SYS. AS FAR AS PCPN AMTS ARE CONCERNED...THE GFS AND ESPECIALLY THE NAM BOTH SHOW SHARP H8-7 FGEN ON THE WRN FLANK OF THE H7 LO TRACK (NAM PLACEMENT IS A BIT FARTHER W...GFS TO THE E). WITH 4 G/KG SPECIFIC HUMIDITY AVBL AND A 12HR PD OF UVV...SN AMTS OF 8"/12 HRS WOULD BE PSBL UNDER THIS SHARPEST DEFORMATION ZN. ATLHOUGH SN/WATER RATIOS WL LIKELY BE LO (10:1) WITH RATHER NARROW DGZ SHOWN ON BUFKIT SDNGS...HVY/WET NATURE OF THE SN AND LOWER WRNG CRITERIA (6"/12HRS) FOR THE WI BORDER COUNTIES SEEMS TO JUSTIFY A WATCH THERE...ESPECIALLY SINCE BULK OF SN WL FALL DURING THE NGT WHEN HTG OF THE LLVLS WL BE ABSENT. ALSO DECIDED TO ISSUE A WATCH FOR MQT COUNTY WITH POTENTIAL FOR SOME UPSLOPE ENHANCEMENT OF THE PCPN WITH FAIRLY TIGHT NNE FLOW PERPENDICULAR TO THE TERRAIN CONTOURS. QUICK LOOK AT THE 00Z ECMWF SEEMS TO JUSTIFY WATCH ISSUANCE WITH CLASSIC COMMA HEAD HIER RH PATTERN ON THE CYC SIDE OF H7 LO/H5 VORT TRACK THRU THE UPR LKS. COORDINATED WITH GRB/DLH/APX/LOT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... TAMDAR SOUNDING SHOW VERY DRY BELOW THE CURRENT MID/HIGH CLOUDS. RAIN SHOULD MOVE INTO CMX AT 09Z...WITH CIGS AND VSBYS DROPPING THANKS TO THE EASTERLY UPSLOPE FLOW. LIFR POSSIBLE AT CMX BETWEEN 14-17Z. A SE WIND AT SAW IS A WEAKER UPSLOPE FLOW THERE...WITH IFR VIS AND MVFR CIGS FIGURED LATE THIS MORNING. CIGS AND VSBYS WILL IMPROVE IN THE AFTERNOON AS THE UPPER LEVEL PORTION OF THE STORM SYSTEM CROSSES UPPER MI...ALLOWING WINDS TO TURN TO DIRECTIONS MORE FAVORABLE FOR BRINGING LOWER LEVEL DRY AIR IN. HOWEVER...DAYTIME HEATING COMBINED WITH THE COLD UPPER LEVEL PORTION OF THE STORM COULD RESULT IN SOME SCATTERED SHOWERS. DIURNAL PCPN NOT NEARLY AS FAVORABLE AT CMX...BUT KEPT MVFR CIG DUE TO LINGERING LOW LEVEL MOISTURE. MODELS INDICATE THAT THE UPPER LEVEL MOISTURE EXITS...AND WITH AN UPSLOPE NW WIND AT CMX FOR -FZDZ. NW AT SAW SHOULD RESULT IN A DRY FORECAST WITH SOME MVFR CIGS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRES WILL MOVE NORTHEASTWARD ACROSS THE AREA...AND INTO ONTARIO LATE THIS EVENING. 20 TO 30 KT GUSTS WILL DIMINISH AS THE LOW MOVES OVERHEAD...AND HIGH PRESSURE BEGINS TO FILTER IN THIS EVENING. THE NEXT PERIOD OF POTENTIAL GALES LOOKS TO BE LATE TUESDAY NIGHT INTO WEDNESDAY...AS A SFC LOW SLIDES UP FROM THE SOUTHWEST. THE TRACK SHOULD BRING IT OVER FAR EASTERN LS TO LH BY WEDNESDAY MORNING. KEEPING JUST BELOW GALES AT THE MOMENT...BUT WOULD NOT BE SURPRISED IF GALES WILL BE NEEDED. TOWARDS THE END OF THE PERIOD...YET ANOTHER SFC LOW SLIDES NORTHEASTWARD TOWARDS LM FRIDAY. AT THIS TIME THIS LAST LOW SEEMS TO BE THE STRONGEST...WITH THE BEST CHANCE FOR LS WIDE GALES FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ005. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && && $$ DISCUSSION...KC AVIATION...AJ/KF MARINE...KF mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1230 AM EDT MON APR 7 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE. .UPDATE... (ISSUED 741 PM EDT SUN APR 6) LATEST 18Z NAM/GFS AND 21Z RUC CONTINUE TO SHOW A SLOWER ARRIVAL OF PCPN INTO THE CWA. THERE APPEARS TO BE A FEW REASONS FOR THIS. FIRST...A LOOP OF THE WATER VAPOR IMAGERY AND RUC 500MB HEIGHTS INDICATES BUILDING RIDGING OVER THE CWA AHEAD OF THE UPPER LOW IN SE SOUTH DAKOTA BECOMING NEGATIVELY TILTED. THIS PLACES THE AREA UNDER SUBSIDENCE ALOFT. SECOND...TAMDAR SOUNDINGS FROM THE LAST FEW HOURS AT HOUGHTON...SAWYER...APPLETON AND MUSKEGON ALL DEPICT A LOT OF DRY AIR BELOW 700 MB (APPLETON AND MUSKEGON HAD DEWPOINT DEPRESSIONS OF 20-25C BETWEEN 700-800MB). SINCE THE UPPER LOW IS BECOMING NEGATIVELY TILTED...THE LOW LEVEL WINDS END UP TURNING SOUTH TO SOUTHEASTERLY...WHICH WOULD KEEP FEEDING DRY AIR INTO THE CWA. RADAR LOOP OF THE WARM CONVEYOR BELT OVER ERN MN/ERN IA AND FAR WESTERN WI HAVE SHOWN SOME OF THE EFFECTS OF THIS DRY AIR...WITH A CLUSTER OF HEAVIER PCPN NW OF DUBUQUE HAS ALMOST DISSIPATED AS IT LIFTED NNE. THEREFORE...THINK THE SLOWER TREND DEPICTED BY THE 18Z NAM/GFS AND 21Z RUC IS VALID...AND HAVE MODIFIED THE FORECAST FOR TONIGHT TOWARDS THESE MODELS. THERE ARE A FEW OTHER ITEMS TO NOTE TOO. THE DRY SLOT ASSOCIATED WITH THE UPPER LOW...SEEN WELL ON VISIBLE WITH CLEARING JUST TO THE WEST OF I-35 BETWEEN MSP AND DSM...HAS BEEN MOVING EASTWARD QUICKLY. IT IS POSSIBLE THAT COMBINATION OF THE FAST MOVING DRY SLOT AND THE DRY AIR OVER ERN WI COULD CAUSE THE WARM CONVEYOR BELT PCPN TO NARROW WITH TIME. ALSO...WITH MODELS TAKING A TRACK OF THE UPPER LOW ACROSS SRN MN AND BUILDING RIDGING OCCURRING UP ACROSS THE CWA AND WESTERN LAKE SUPERIOR...WARMER LOW TO MID LEVEL AIR IS PUSHED WESTWARD THROUGH THE NIGHT. THEREFORE...THE GFS/NAM BOTH DEPICT WET-BULB ZERO HEIGHTS AT OR ABOVE 3000 FT AT 06Z AND 12Z MON OVER MUCH OF NW WI...SUGGESTING ONLY RAIN WILL FALL. GIVEN THIS...PULLED ANY MENTION OF SNOW ACROSS THE U.P.. && .SYNOPSIS... (ISSUED 445 PM EDT SUN APR 6) BROAD CYCLONIC FLOW ALOFT OVR MUCH OF THE CONUS. STRONG SHORTWAVE WITHIN THIS FLOW IS STILL SPINNING OUT OVR SD. RIBBON OF INCREASED H85-H7 MOISTURE STREAMING AHEAD OF THE FEATURE IS RESULTING IN SWATH OF RAIN SHOWERS ALONG COLD FRONT FROM FM NORTHERN IA INTO WESTERN WI AND MUCH OF MN. DEFORMATION PCPN IN FORM OF HEAVY SNOW HAS AFFECTED EASTERN ND INTO NORTHERN MN MUCH OF THE DAY. SO FAR...JUST MID CLOUDS ACROSS FORECAST AREA AS NO PCPN HAS MADE IT INTO UPR MI DUE TO VERY DRY AIR IN LOW-MID LEVELS SEEN ON TAMDAR SOUNDINGS AT SAW AND 12Z UPSTREAM SOUNDINGS AT GRB/DVN. MUCH FARTHER UPSTREAM ON WEST EDGE OF THE LARGE SCALE TROUGH...CLUSTER OF SHORTWAVES ARE SHIFTING ONTO THE WESTERN COAST. LEAD SHORTWAVE WILL HELP DEVELOP LOW PRESSURE SYSTEM OVER THE PLAINS LATE MONDAY. IT IS THIS LOW THAT COULD BRING NEXT SIGNIFICANT PCPN TO UPR MI TUE-WED. && .SHORT TERM (TONIGHT AND MONDAY)... (ISSUED 445 PM EDT SUN APR 6) SLOWER PROGRESSION OF UPR LOW AND SFC LOW OVR MN LEADS MINIMAL PTYPE ISSUES TONIGHT. SINCE UPR MI IS WITHIN WARM SECTOR AHEAD OF SFC LOW...JUST RAIN IS EXPECTED. EXCEPTION IS OVER FAR WRN UPR NEAR IWD WHERE THERE COULD BE SOME SNOWFLAKES MIX WITH RAIN LATE. AS FOR PCPN COVERAGE...THAT IS STILL UNFOLDING AT THIS HOUR. FOR THE MOST PART...MODELS ARE IN GOOD AGREEMENT WITH LARGE SCALE FEATURES THROUGH MONDAY. INITIAL SHOWERS ARE CAPTURED WELL LOOKING AT 300K ISENTROPIC SFC (H7-H6). MOST CONCENTRATED PCPN OCCURS THIS EVENING OVR FAR WEST UPR MI UPSTREAM OF CURRENT BATCH OF SHOWERS. COULD BE A LULL AFTER THESE SHOWERS MOVE THROUGH AS NEXT SHOWERS IN THE WARM ADVECTION REGIME DEVELOP THIS EVENING JUST AHEAD OF COLD FRONT AND SHORTWAVE TROUGH. DECENT AGREEMENT THAT SECOND BATCH OF RAIN DOES NOT ARRIVE UNTIL AFT 06Z IN WESTERN CWA AND MORE TOWARD 12Z IN CNTRL. DID NOT GET THAT SPECIFIC YET AS ONGOING WARM AIR ADVECTION MAY BE SUFFICIENT ENOUGH TO POP SOME SHOWERS EARLIER AHEAD OF THE MORE SYNOPTICALLY FORCED AXIS OF MOISTURE/SHOWERS. HIGHEST POPS ON MON WILL BE OVR CNTRL AND EAST CWA AS DEEP MOISTURE AND LIFT SHIFT ACROSS AHEAD OF SHORTWAVE. PUT SOME SLIGHT CHANCES OF THUNDER OVR SOUTHEAST LATE TONIGHT INTO MON MORNING ON EDGE OF DRY SLOT AS COOLING ALOFT (H5 TEMPS BLO -25C) AND LINGERING 925-850MB THERMAL RIDGE (925MB TEMPS NEAR +8C) STEEPENS LAPSE RATES. BEST CHANCE WILL BE OVR NORTHERN LK MI INTO ADJACENT PORTIONS OF UPR MI. STILL A POTENTIAL FOR REDEVELOPMENT OF SHOWERS ON MONDAY OVR MUCH OF CWA WITH SHORTWAVE AND STEEP LAPSE RATES OVER THE AREA. COVERAGE OF SHOWERS DEPENDS ON HOW MUCH HEATING CAN OCCUR AFTER MORNING PCPN AND LOW CLOUDS/FOG DEPART. MIXING TO H9 IN AFTN SUPPORTS TEMPS WELL INTO THE 50S OVR CNTRL AND ERN CWA WHILE TEMPS SHOULD STAY STEADY OR SLOWLY FALL FAR WEST AS COLD AIR BANKED OVR MN ALL WEEKEND FINALLY WORKS TOWARD THE EAST. DUE TO THE COLD AIR ADVECTION...ANY RAIN SHOWERS COULD BE MIXED WITH SNOW IN THE FAR WEST. NO ACCUM THOUGH AS SFC TEMPS WILL STILL BE WELL ABOVE 32. .LONG TERM (MON NIGHT THRU SUN)... (ISSUED 445 PM EDT SUN APR 6) ACTIVE PATTERN CONTINUES DURING THIS TIME FRAME WITH 2 STORM SYSTEMS TO AFFECT THE FCST AREA. THE MOST SIGNIFICANT ONE WILL BE LATE IN THE WEEK. FIRST SYSTEM WILL MOVE FROM THE SRN PLAINS TUE TO THE UPPER LAKES WED MORNING. GFS...LIKE A FEW OF ITS RECENT RUNS...IS AN OUTLIER SOLUTION...BEING WEAKER WITH SHORTWAVE AND FARTHER E WITH SFC LOW. WITH LACK OF SUPPORT FROM ANY OTHER MODELS...WILL DISCARD ITS SOLUTION. GLOBAL CANADIAN/UKMET/ECMWF ARE IN GOOD AGREEMENT IN CLOSING OFF A SMALL 500MB LOW AS SYSTEM REACHES THE UPPER LAKES. ACTUALLY...THE ECMWF AND CANADIAN ARE ALMOST IDENTICAL IN PLACEMENT OF SFC LOW OVER FAR ERN UPPER MI AND MIDLEVEL CENTER OVER WRN UPPER MI AT 12Z WED. SINCE THIS SOLUTION IS SIMILAR TO THE CONSENSUS OF MODEL RUNS OVER THE LAST DAY OR SO...AND SINCE THE ECMWF IS NOW SHOWING EXCELLENT CONTINUITY ON THIS TRACK...WILL UTILIZE ECMWF/CANADIAN FOR THE DETAILS OF THIS STORM SYSTEM. BY THE WAY... THE NAM ALSO SUPPORTS THE PREFERRED SOLUTION...THOUGH IT IS SLIGHTLY W AND MUCH MORE AGGRESSIVE WITH WARMING INTO CNTRL/ERN UPPER MI. FOR THE DETAILS...ANY LINGERING LIGHT PCPN WITH EXITING SYSTEM MON WILL END MON NIGHT...AND THEN EXPECT DRY WEATHER TO PREVAIL FOR MUCH OF THE DAY TUE. AS SHORTWAVE HEADS OUT OF THE WRN PLAINS TUE MORNING TOWARD THE UPPER MISSISSIPPI VALLEY BY EVENING...NICE BULLSEYE OF STRENGTHENING DEEP LAYER QVECTOR CONVERGENCE DEVELOPS NE TOWARD THE UPPER LAKES AS SHORTWAVE BEGINS TO CLOSE OFF TO A MIDLEVEL LOW. IN RESPONSE...INCREASING SRLY FLOW AHEAD OF SYSTEM TRANSPORTS A SURGE OF GULF MOISTURE N WITH INTENSIFYING ISENTROPIC ASCENT. 295K SFC (700-750MB) SHOWS MIXING RATIOS OF 4G/KG AVBL TUE NIGHT WHICH COULD TRANSLATE TO UP TO 8 INCHES OF WET SNOW WHERE PCPN CAN FALL AS ALL SNOW. SINCE DETAILED FCST SOUNDINGS ARE NOT AVBL FOR THE PREFERRED MODELS...USE OF 1000-850MB THICKNESSES SUGGESTS PCPN SHOULD FALL AS MAINLY SNOW W OF ROUGHLY A KIMT TO KMQT LINE WITH PCPN TRENDING TOWARD MAINLY RAIN ALONG LAKE MI SHORELINE. WHERE PCPN FALLS MOSTLY AS SNOW...IT WILL BE ANOTHER VERY WET/HVY SNOWFALL WITH LOW SNOW TO WATER RATIOS. AT THE MOMENT...IT LOOKS LIKE ACCUMULATIONS WILL BE IN THE 4-7 INCH RANGE WEST OF KIMT TO KMQT. PCPN WILL DIMINISH WED AS SYSTEM PULLS AWAY. THU THRU SUN...FOR A NUMBER OF DAYS...THE MAJORITY OF GLOBAL CANADIAN/GFS/ECWMF RUNS HAVE BEEN INDICATING A MAJOR STORM SYSTEM TO AFFECT THE MIDWEST/GREAT LAKES REGION LATE THIS WEEK. LATEST ROUND OF MODEL RUNS (00Z/06Z/12Z TODAY) HAVE NOT WAVERED MUCH...SO THERE CONTINUES TO BE A STRONG/PERSISTENT SIGNAL FOR A MAJOR SYSTEM. OVER THE LAST SEVERAL DAYS...MODEL FCST TRACK OF SFC LOW PRES HAS RANGED FROM THE ERN DAKOTAS/WRN MN TO THE CNTRL OR EVEN LWR GREAT LAKES... RESULTING IN A VARIETY OF OUTCOMES FOR UPPER MI RANGING FROM VERY WARM WITH SHRA/TSRA TO A MAJOR WINTER STORM TO VERY LITTLE PCPN. OBVIOUSLY...DETAILS WILL BE UNCERTAIN FOR SEVERAL MORE DAYS...BUT THE OVERALL TREND RECENTLY HAS BEEN TO NARROW TRACK DOWN SOMEWHAT TO ONE FROM THE SOUTHERN PLAINS TO LWR MI. HOWEVER...DESPITE THIS RECENT TREND...THIS SYSTEM IS CERTAINLY FAR ENOUGH OUT INTO THE FCST PERIOD THAT RECENT TRENDS CANNOT BE RELIED ON. ALL THAT CAN BE SAID IS THERE IS A SIGNAL FOR A MAJOR SPRING STORM IN THE MIDWEST/GREAT LAKES/OHIO VALLEY REGION LATE IN THE WEEK...AND THAT IT IS ONE THAT COULD RESULT IN A SIGNIFICANT LATE SEASON WINTER STORM AFFECTING AT LEAST PARTS OF UPPER MI. TIME PERIOD LOOKS TO BE THU NIGHT THRU SAT. FCST WILL INCLUDE RAIN/SNOW AS PTYPES FOR MUCH OF THAT TIME FRAME. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... TAMDAR SOUNDING SHOW VERY DRY BELOW THE CURRENT MID/HIGH CLOUDS. RAIN SHOULD MOVE INTO CMX AT 09Z...WITH CIGS AND VSBYS DROPPING THANKS TO THE EASTERLY UPSLOPE FLOW. LIFR POSSIBLE AT CMX BETWEEN 14-17Z. A SE WIND AT SAW IS A WEAKER UPSLOPE FLOW THERE...WITH IFR VIS AND MVFR CIGS FIGURED LATE THIS MORNING. CIGS AND VSBYS WILL IMPROVE IN THE AFTERNOON AS THE UPPER LEVEL PORTION OF THE STORM SYSTEM CROSSES UPPER MI...ALLOWING WINDS TO TURN TO DIRECTIONS MORE FAVORABLE FOR BRINGING LOWER LEVEL DRY AIR IN. HOWEVER...DAYTIME HEATING COMBINED WITH THE COLD UPPER LEVEL PORTION OF THE STORM COULD RESULT IN SOME SCATTERED SHOWERS. DIURNAL PCPN NOT NEARLY AS FAVORABLE AT CMX...BUT KEPT MVFR CIG DUE TO LINGERING LOW LEVEL MOISTURE. MODELS INDICATE THAT THE UPPER LEVEL MOISTURE EXITS...AND WITH AN UPSLOPE NW WIND AT CMX FOR -FZDZ. NW AT SAW SHOULD RESULT IN A DRY FORECAST WITH SOME MVFR CIGS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... ACTIVE PERIOD ON THE LAKE WITH THREE STRONG LOW PRESSURE SYSTEMS IMPACTING WINDS THIS WEEK. INITIALLY...WILL CONTEND WITH LOW END NORTHEAST GALES OVER WESTERN LK SUPERIOR AS SFC LOW PUSHES INTO WESTERN UPR MI. NEXT POTENTIAL FOR STRONGER WINDS...TO 30 KNOTS... ARRIVES LATE TUESDAY...AGAIN OVER WESTERN LK SUPERIOR DUE TO NE WINDS FUNNELING TOWARD HEAD OF LK SUPERIOR. FINALLY...A STRONG LOW PRESSURE SYSTEM LIFTING INTO UPR GREAT LAKES LATE WEEK MAY PRODUCE GALES OVR MUCH OF LAKE SUPERIOR ON FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING UNTIL MIDNIGHT EDT MON LSZ162. LAKE MICHIGAN...NONE. && $$ UPDATE...AJ SYNOPSIS/SHORT TERM...JLA LONG TERM...ROLFSON AVIATION...AJ/KF MARINE...JLA mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 741 PM EDT SUN APR 6 2008 IN ADDITION TO INSERTION OF UPDATE SECTION...UPDATED AVIATION DISCUSSION FOR 00Z TAF ISSUANCE. .UPDATE... LATEST 18Z NAM/GFS AND 21Z RUC CONTINUE TO SHOW A SLOWER ARRIVAL OF PCPN INTO THE CWA. THERE APPEARS TO BE A FEW REASONS FOR THIS. FIRST...A LOOP OF THE WATER VAPOR IMAGERY AND RUC 500MB HEIGHTS INDICATES BUILDING RIDGING OVER THE CWA AHEAD OF THE UPPER LOW IN SE SOUTH DAKOTA BECOMING NEGATIVELY TILTED. THIS PLACES THE AREA UNDER SUBSIDENCE ALOFT. SECOND...TAMDAR SOUNDINGS FROM THE LAST FEW HOURS AT HOUGHTON...SAWYER...APPLETON AND MUSKEGON ALL DEPICT A LOT OF DRY AIR BELOW 700 MB (APPLETON AND MUSKEGON HAD DEWPOINT DEPRESSIONS OF 20-25C BETWEEN 700-800MB). SINCE THE UPPER LOW IS BECOMING NEGATIVELY TILTED...THE LOW LEVEL WINDS END UP TURNING SOUTH TO SOUTHEASTERLY...WHICH WOULD KEEP FEEDING DRY AIR INTO THE CWA. RADAR LOOP OF THE WARM CONVEYOR BELT OVER ERN MN/ERN IA AND FAR WESTERN WI HAVE SHOWN SOME OF THE EFFECTS OF THIS DRY AIR...WITH A CLUSTER OF HEAVIER PCPN NW OF DUBUQUE HAS ALMOST DISSIPATED AS IT LIFTED NNE. THEREFORE...THINK THE SLOWER TREND DEPICTED BY THE 18Z NAM/GFS AND 21Z RUC IS VALID...AND HAVE MODIFIED THE FORECAST FOR TONIGHT TOWARDS THESE MODELS. THERE ARE A FEW OTHER ITEMS TO NOTE TOO. THE DRY SLOT ASSOCIATED WITH THE UPPER LOW...SEEN WELL ON VISIBLE WITH CLEARING JUST TO THE WEST OF I-35 BETWEEN MSP AND DSM...HAS BEEN MOVING EASTWARD QUICKLY. IT IS POSSIBLE THAT COMBINATION OF THE FAST MOVING DRY SLOT AND THE DRY AIR OVER ERN WI COULD CAUSE THE WARM CONVEYOR BELT PCPN TO NARROW WITH TIME. ALSO...WITH MODELS TAKING A TRACK OF THE UPPER LOW ACROSS SRN MN AND BUILDING RIDGING OCCURRING UP ACROSS THE CWA AND WESTERN LAKE SUPERIOR...WARMER LOW TO MID LEVEL AIR IS PUSHED WESTWARD THROUGH THE NIGHT. THEREFORE...THE GFS/NAM BOTH DEPICT WET-BULB ZERO HEIGHTS AT OR ABOVE 3000 FT AT 06Z AND 12Z MON OVER MUCH OF NW WI...SUGGESTING ONLY RAIN WILL FALL. GIVEN THIS...PULLED ANY MENTION OF SNOW ACROSS THE U.P.. && .SYNOPSIS... BROAD CYCLONIC FLOW ALOFT OVR MUCH OF THE CONUS. STRONG SHORTWAVE WITHIN THIS FLOW IS STILL SPINNING OUT OVR SD. RIBBON OF INCREASED H85-H7 MOISTURE STREAMING AHEAD OF THE FEATURE IS RESULTING IN SWATH OF RAIN SHOWERS ALONG COLD FRONT FROM FM NORTHERN IA INTO WESTERN WI AND MUCH OF MN. DEFORMATION PCPN IN FORM OF HEAVY SNOW HAS AFFECTED EASTERN ND INTO NORTHERN MN MUCH OF THE DAY. SO FAR...JUST MID CLOUDS ACROSS FORECAST AREA AS NO PCPN HAS MADE IT INTO UPR MI DUE TO VERY DRY AIR IN LOW-MID LEVELS SEEN ON TAMDAR SOUNDINGS AT SAW AND 12Z UPSTREAM SOUNDINGS AT GRB/DVN. MUCH FARTHER UPSTREAM ON WEST EDGE OF THE LARGE SCALE TROUGH...CLUSTER OF SHORTWAVES ARE SHIFTING ONTO THE WESTERN COAST. LEAD SHORTWAVE WILL HELP DEVELOP LOW PRESSURE SYSTEM OVER THE PLAINS LATE MONDAY. IT IS THIS LOW THAT COULD BRING NEXT SIGNIFICANT PCPN TO UPR MI TUE-WED. && .SHORT TERM (TONIGHT AND MONDAY)... SLOWER PROGRESSION OF UPR LOW AND SFC LOW OVR MN LEADS MINIMAL PTYPE ISSUES TONIGHT. SINCE UPR MI IS WITHIN WARM SECTOR AHEAD OF SFC LOW...JUST RAIN IS EXPECTED. EXCEPTION IS OVER FAR WRN UPR NEAR IWD WHERE THERE COULD BE SOME SNOWFLAKES MIX WITH RAIN LATE. AS FOR PCPN COVERAGE...THAT IS STILL UNFOLDING AT THIS HOUR. FOR THE MOST PART...MODELS ARE IN GOOD AGREEMENT WITH LARGE SCALE FEATURES THROUGH MONDAY. INITIAL SHOWERS ARE CAPTURED WELL LOOKING AT 300K ISENTROPIC SFC (H7-H6). MOST CONCENTRATED PCPN OCCURS THIS EVENING OVR FAR WEST UPR MI UPSTREAM OF CURRENT BATCH OF SHOWERS. COULD BE A LULL AFTER THESE SHOWERS MOVE THROUGH AS NEXT SHOWERS IN THE WARM ADVECTION REGIME DEVELOP THIS EVENING JUST AHEAD OF COLD FRONT AND SHORTWAVE TROUGH. DECENT AGREEMENT THAT SECOND BATCH OF RAIN DOES NOT ARRIVE UNTIL AFT 06Z IN WESTERN CWA AND MORE TOWARD 12Z IN CNTRL. DID NOT GET THAT SPECIFIC YET AS ONGOING WARM AIR ADVECTION MAY BE SUFFICIENT ENOUGH TO POP SOME SHOWERS EARLIER AHEAD OF THE MORE SYNOPTICALLY FORCED AXIS OF MOISTURE/SHOWERS. HIGHEST POPS ON MON WILL BE OVR CNTRL AND EAST CWA AS DEEP MOISTURE AND LIFT SHIFT ACROSS AHEAD OF SHORTWAVE. PUT SOME SLIGHT CHANCES OF THUNDER OVR SOUTHEAST LATE TONIGHT INTO MON MORNING ON EDGE OF DRY SLOT AS COOLING ALOFT (H5 TEMPS BLO -25C) AND LINGERING 925-850MB THERMAL RIDGE (925MB TEMPS NEAR +8C) STEEPENS LAPSE RATES. BEST CHANCE WILL BE OVR NORTHERN LK MI INTO ADJACENT PORTIONS OF UPR MI. STILL A POTENTIAL FOR REDEVELOPMENT OF SHOWERS ON MONDAY OVR MUCH OF CWA WITH SHORTWAVE AND STEEP LAPSE RATES OVER THE AREA. COVERAGE OF SHOWERS DEPENDS ON HOW MUCH HEATING CAN OCCUR AFTER MORNING PCPN AND LOW CLOUDS/FOG DEPART. MIXING TO H9 IN AFTN SUPPORTS TEMPS WELL INTO THE 50S OVR CNTRL AND ERN CWA WHILE TEMPS SHOULD STAY STEADY OR SLOWLY FALL FAR WEST AS COLD AIR BANKED OVR MN ALL WEEKEND FINALLY WORKS TOWARD THE EAST. DUE TO THE COLD AIR ADVECTION...ANY RAIN SHOWERS COULD BE MIXED WITH SNOW IN THE FAR WEST. NO ACCUM THOUGH AS SFC TEMPS WILL STILL BE WELL ABOVE 32. .LONG TERM... (MON NIGHT THRU SUN) ACTIVE PATTERN CONTINUES DURING THIS TIME FRAME WITH 2 STORM SYSTEMS TO AFFECT THE FCST AREA. THE MOST SIGNIFICANT ONE WILL BE LATE IN THE WEEK. FIRST SYSTEM WILL MOVE FROM THE SRN PLAINS TUE TO THE UPPER LAKES WED MORNING. GFS...LIKE A FEW OF ITS RECENT RUNS...IS AN OUTLIER SOLUTION...BEING WEAKER WITH SHORTWAVE AND FARTHER E WITH SFC LOW. WITH LACK OF SUPPORT FROM ANY OTHER MODELS...WILL DISCARD ITS SOLUTION. GLOBAL CANADIAN/UKMET/ECMWF ARE IN GOOD AGREEMENT IN CLOSING OFF A SMALL 500MB LOW AS SYSTEM REACHES THE UPPER LAKES. ACTUALLY...THE ECMWF AND CANADIAN ARE ALMOST IDENTICAL IN PLACEMENT OF SFC LOW OVER FAR ERN UPPER MI AND MIDLEVEL CENTER OVER WRN UPPER MI AT 12Z WED. SINCE THIS SOLUTION IS SIMILAR TO THE CONSENSUS OF MODEL RUNS OVER THE LAST DAY OR SO...AND SINCE THE ECMWF IS NOW SHOWING EXCELLENT CONTINUITY ON THIS TRACK...WILL UTILIZE ECMWF/CANADIAN FOR THE DETAILS OF THIS STORM SYSTEM. BY THE WAY... THE NAM ALSO SUPPORTS THE PREFERRED SOLUTION...THOUGH IT IS SLIGHTLY W AND MUCH MORE AGGRESSIVE WITH WARMING INTO CNTRL/ERN UPPER MI. FOR THE DETAILS...ANY LINGERING LIGHT PCPN WITH EXITING SYSTEM MON WILL END MON NIGHT...AND THEN EXPECT DRY WEATHER TO PREVAIL FOR MUCH OF THE DAY TUE. AS SHORTWAVE HEADS OUT OF THE WRN PLAINS TUE MORNING TOWARD THE UPPER MISSISSIPPI VALLEY BY EVENING...NICE BULLSEYE OF STRENGTHENING DEEP LAYER QVECTOR CONVERGENCE DEVELOPS NE TOWARD THE UPPER LAKES AS SHORTWAVE BEGINS TO CLOSE OFF TO A MIDLEVEL LOW. IN RESPONSE...INCREASING SRLY FLOW AHEAD OF SYSTEM TRANSPORTS A SURGE OF GULF MOISTURE N WITH INTENSIFYING ISENTROPIC ASCENT. 295K SFC (700-750MB) SHOWS MIXING RATIOS OF 4G/KG AVBL TUE NIGHT WHICH COULD TRANSLATE TO UP TO 8 INCHES OF WET SNOW WHERE PCPN CAN FALL AS ALL SNOW. SINCE DETAILED FCST SOUNDINGS ARE NOT AVBL FOR THE PREFERRED MODELS...USE OF 1000-850MB THICKNESSES SUGGESTS PCPN SHOULD FALL AS MAINLY SNOW W OF ROUGHLY A KIMT TO KMQT LINE WITH PCPN TRENDING TOWARD MAINLY RAIN ALONG LAKE MI SHORELINE. WHERE PCPN FALLS MOSTLY AS SNOW...IT WILL BE ANOTHER VERY WET/HVY SNOWFALL WITH LOW SNOW TO WATER RATIOS. AT THE MOMENT...IT LOOKS LIKE ACCUMULATIONS WILL BE IN THE 4-7 INCH RANGE WEST OF KIMT TO KMQT. PCPN WILL DIMINISH WED AS SYSTEM PULLS AWAY. THU THRU SUN...FOR A NUMBER OF DAYS...THE MAJORITY OF GLOBAL CANADIAN/GFS/ECWMF RUNS HAVE BEEN INDICATING A MAJOR STORM SYSTEM TO AFFECT THE MIDWEST/GREAT LAKES REGION LATE THIS WEEK. LATEST ROUND OF MODEL RUNS (00Z/06Z/12Z TODAY) HAVE NOT WAVERED MUCH...SO THERE CONTINUES TO BE A STRONG/PERSISTENT SIGNAL FOR A MAJOR SYSTEM. OVER THE LAST SEVERAL DAYS...MODEL FCST TRACK OF SFC LOW PRES HAS RANGED FROM THE ERN DAKOTAS/WRN MN TO THE CNTRL OR EVEN LWR GREAT LAKES... RESULTING IN A VARIETY OF OUTCOMES FOR UPPER MI RANGING FROM VERY WARM WITH SHRA/TSRA TO A MAJOR WINTER STORM TO VERY LITTLE PCPN. OBVIOUSLY...DETAILS WILL BE UNCERTAIN FOR SEVERAL MORE DAYS...BUT THE OVERALL TREND RECENTLY HAS BEEN TO NARROW TRACK DOWN SOMEWHAT TO ONE FROM THE SOUTHERN PLAINS TO LWR MI. HOWEVER...DESPITE THIS RECENT TREND...THIS SYSTEM IS CERTAINLY FAR ENOUGH OUT INTO THE FCST PERIOD THAT RECENT TRENDS CANNOT BE RELIED ON. ALL THAT CAN BE SAID IS THERE IS A SIGNAL FOR A MAJOR SPRING STORM IN THE MIDWEST/GREAT LAKES/OHIO VALLEY REGION LATE IN THE WEEK...AND THAT IT IS ONE THAT COULD RESULT IN A SIGNIFICANT LATE SEASON WINTER STORM AFFECTING AT LEAST PARTS OF UPPER MI. TIME PERIOD LOOKS TO BE THU NIGHT THRU SAT. FCST WILL INCLUDE RAIN/SNOW AS PTYPES FOR MUCH OF THAT TIME FRAME. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... WARM CONVEYOR BELT OF RAIN SHOWERS CONTINUES TO DEVELOP OVER ERN MN/ERN IA AND WESTERN WI. AHEAD OF THIS PCPN...THE AIR IS VERY DRY BELOW THE CURRENT MID/HIGH CLOUDS MOVING ACROSS AS SEEN ON TAMDAR SOUNDINGS. THIS DRY AIR SHOULD KEEP A SLOW PROGRESSION EASTWARD OF THIS PCPN...DESPITE THAT THE OVERALL STORM SYSTEM...LOCATED NEAR MSP...WILL BE LIFTING NORTHEAST. ONCE RAIN MOVES INTO CMX LATE TONIGHT...CIGS AND VSBYS SHOULD DROP THANKS TO THE EASTERLY UPSLOPE FLOW. HAVE LEFT THE POSSIBLITY FOR SOME LIFR CONDITIONS AT CMX BETWEEN 14-17Z. A SE WIND AT SAW IS ALSO AN UPSLOPE WIND THERE...BUT IT IS NOT NEARLY AS DRAMATIC AT CMX. THUS...THE GOING POSSIBILTY OF IFR VIS AND MVFR CIGS SEEM REASONABLE THERE LATE TOMORROW MORNING. CIGS AND VSBYS WILL IMPROVE DURING THE AFTERNOON AS THE UPPER LEVEL PORTION OF THE STORM SYSTEM CROSSES UPPER MI...ALLOWING WINDS TO TURN TO DIRECTIONS MORE FAVORABLE FOR BRINGING LOWER LEVEL DRY AIR IN. HOWEVER...DAYTIME HEATING COMBINED WITH THE COLD UPPER LEVEL PORTION OF THE STORM COULD RESULT IN SOME SCATTERED SHOWERS...AND HAVE REPRESENTED THIS AT SAW WITH A PROB30 GROUP OF MVFR VIS. DIURNAL PCPN NOT NEARLY AS FAVORABLE AT CMX...BUT STILL MAINTAINED A GOING MVFR CIG THERE DUE TO LINGERING LOW LEVEL MOISTURE. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... ACTIVE PERIOD ON THE LAKE WITH THREE STRONG LOW PRESSURE SYSTEMS IMPACTING WINDS THIS WEEK. INITIALLY...WILL CONTEND WITH LOW END NORTHEAST GALES OVER WESTERN LK SUPERIOR AS SFC LOW PUSHES INTO WESTERN UPR MI. NEXT POTENTIAL FOR STRONGER WINDS...TO 30 KNOTS... ARRIVES LATE TUESDAY...AGAIN OVER WESTERN LK SUPERIOR DUE TO NE WINDS FUNNELLING TOWARD HEAD OF LK SUPERIOR. FINALLY...A STRONG LOW PRESSURE SYSTEM LIFTING INTO UPR GREAT LAKES LATE WEEK MAY PRODUCE GALES OVR MUCH OF LAKE SUPERIOR ON FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING UNTIL MIDNIGHT EDT MON LSZ162. LAKE MICHIGAN...NONE. && $$ UPDATE...AJ SYNOPSIS/SHORT TERM...JLA LONG TERM...ROLFSON AVIATION...AJ MARINE...JLA mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 125 PM EDT SUN APR 6 2008 UPDATED AVIATION SECTION FOR 18Z TAFS .UPDATE... LOT OF DRY AIR ON TAMDAR SOUNDING FM KSAW AND UPSTREAM SOUNDINGS AT GRB/DVN. SO...PCPN LOOKS LIKE IT WILL TAKE A BIT LONGER TO ARRIVE. LATEST NAM...RUC 13...AND LOCAL WRF-ARW INDICATE PCPN INTO FAR SW BTWN 21Z AND 03Z. BASED ON CLUSTER OF SHOWERS OVR NORTHEAST IA INTO SOUTHEAST MN WENT FOR 21Z. IN OUR AREA...SFC FRONT IS CURRENTLY BTWN ASX AND IWD AND THEN RUNS ACROSS NORTHERN UPR MI INTO LK SUPERIOR. NORTH OF THE FRONT...ESSENTIALLY LK SHORE AREAS OF FAR WEST ACROSS KEWEEANW TEMPS WILL STRUGGLE TO 40. SOUTH OF THE FRONT...PARTLY SUNNY SKIES AND DRY LOW TO MID LEVELS SHOULD ALLOW TEMPS TO RISE WELL INTO THE 50S AWAY FM INFLUENCE OF SE FLOW OFF LK MI. PCPN TONIGHT NOT AS FORMIDABLE ON LATEST MODEL RUNS. IN FACT...BASED ON QPF...CNTRL CWA MAY NOT SEE ANY PCPN UNTIL AFT 06Z. THINK VERY DRY AIR UPSTREAM AND SLOWER PROGRESSION OF SFC LOW/TROUGH MAY HAVE SOMETHING TO DO WITH THE TREND. MAY NEED TO MAKE SOME CHANGES TO CURRENT WX GRIDS FOR TONIGHT...BUT WILL HOLD OFF ATTM TO SEE HOW UPSTREAM PCPN PLAYS OUT THIS AFTN. UPDATED/PUBLISHED GRIDS AND ZFPMQT UPDATE ALREADY OUT. && .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW POTENT SHRTWV MOVING EWD INTO THE NRN PLAINS WHILE ARCTIC VORTEX OVER SRN HUDSON BAY IS LIFTING TO THE NE. SFC COLD FNT ON THE SRN PERIPHERY OF COLD AIRMASS ASSOCIATED WITH THIS VORTEX HAS STALLED FM NRN WI TO BTWN MNM-IMT AND JUST N OF ESC/ISQ. 03Z SFC TEMP IS 52 AT MNM WITH 200 DEGREE WIND WHILE IMT IS 39 WITH A NNE WIND. BUT TREND IS FOR WINDS TO VEER MORE TO THE SSE...SO THIS FNT APPEARS TO BE RETURNING N AS A WARM FNT. 00Z GRB/APX/DVN RAOBS ARE QUITE DRY...SO NO PCPN AND JUST SOME SCT CLD COVER NOTED OVER THIS BNDRY IN THIS AREA. BUT SOME SHRA/ ISOLD TS NOTED CLOSE TO THE BNDRY FM THE WRN CWA TO DLH WHERE RUC/ NAM ANALYSIS INDICATE STEEP H7-5 LAPSE RATES AOA 7.5C/KM WITH DEEPER MSTR CLOSER TO SHARPER H8-7 FGEN IN RRQ OF H3 JET AXIS OVER ONTARIO ON SRN FLANK OF HUDSON BAY VORTEX. MAIN FCST CHALLENGES THIS PACKAGE REVOLVE ARND TIMING/IMPACT OF SHRTWV MOVING INTO THE NRN PLAINS. FOR TDAY...SHRTWV TO THE W IS FCST TO REACH SW MN BY 00Z MON...WITH ACCOMPANYING SFC LO NR MPX. THE NAM/GFS SHOW H85 FNT SHIFTING TO THE NW AS SHRTWV TAKES ON A MORE NEGATIVE TILT. THIS SHIFT IN THE POSITION OF THE H85 FNT SUGS THE DEEPER MSTR/WDSPRD PCPN ASSOCIATED WITH SHARPER H8-7 FGEN/RRQ OF UPR JET IN ONTARIO WL SHIFT TO THE NW AND REMAIN THERE THRU THE DAY. CONSIDERING SHIFT IN FRONTAL POSITION...DRYNESS OF THE AIRMASS TO THE S AND SE...AND TENDENCY FOR LARGER SCALE FLOW TO TURN MORE SSE...SUSPECT ANY SHRA NOW OVER THE WRN ZNS WL DIMINISH BY ARND FCST ISSUANCE IN LINE WITH RUC/NAM FCST. TDAY SHOULD FEATURE A GOOD DEAL OF SUNSHINE OVER THE SCNTRL AND ERN ZNS. SSE FLOW OFF LK MI WL HOLD DOWN DIURNAL TEMP RECOVERY FOR THE MOST PART (EXCEPT OVER THE WRN ZNS WHERE THAT FLOW WL DOWNSLOPE)... BUT MIXING TO H85 ON NAM FCST SDNGS STILL RESULTS IN TEMPS APRCHG 55. ALTHOUGH THE H85 FNT LOOKS TO SHIFT TO THE NW OF THE FA...THE BNDRY MAY GET HUNG UP OVER THE KEWEENAW DUE TO THE COOLING INFLUENCE OF LK SUP AND TENDENCY FOR THIS DENSER AIR TO RETARD RETREAT OF NEAR SFC COOL POOL. SO MUCH COOLER THERE. ALTHOUGH THE SSE FLOW WOULD BE A WARMING WIND FM IWD-ONTONAGON...MORE CLDS/SHRA CHCS WL ARRIVE THERE IN THE AFTN WITH APRCH OF DPVA/UPR DIFFLUENCE AHEAD OF SHRTWV AND WARM CONVEYOR BELT MSTR. MORE NEGATIVELY TILTED SHRTWV PROGGED TO MOVE INTO NW WI BY 12Z MON...WITH SFC LO REACHING THE WRN CWA. AS WARM CONVEYOR BELT MSTR PUSHES ACRS THE FA OVERNGT IN THE DPVA/UPR DIFFLUENCE AHEAD OF THE ARPCHG SHRTWV...WL GO WITH ARRIVAL OF CATEGORICAL/LIKELY POPS W-E BEFORE DRY SLOTTING AFT 06Z IMPACTS THE WI BORDER ZNS. LOWERED HIEST POPS AS THE CONVEYOR BELT WORKS E INTO DRY AIR. PCPN WL BE ENTIRELY IN THE FORM OF RA EXCEPT FOR PERHAPS THE IWD AREA LATE WITH ARRIVAL OF COLDER LLVL AIR IN CYC NLY FLOW LATE. BUT ANY SN WL BE INSIGNFICANT WITH DRY SLOTTING ALF. MIN TEMPS WL APRCH 32 OVER THE FAR W...BUT READINGS SHOULD REMAIN WELL ABV 32 ELSEWHERE. ON MON...NAM/GFS FCST SHRTWV/SFC LO TO REACH NE LK SUP BY 00Z TUE. THE GFS FCST TRACK IS A BIT FARTHER S. PER NCEP PREFERENCE...TRENDED AWAY FM THE NAM TOWARD THE GFS. LARGER SCALE PCPN ASSOCIATED WITH THE WARM CONVEYOR BELT MSTR SHOULD EXIT THE ERN ZNS DURING THE AFTN WITH ARRIVAL OF DRY SLOTTING. THE GFS SHOWS PATCH OF HIER MSTR ON CYC SIDE OF H5 VORT TRACK IMPACTING THE FA...WITH FAIRLY STEEP LAPSE RATES UNDER THE MSTR PATCH. WITH LLVL CYC FLOW...WL LINGER CHC POPS THRU THE DAY EXCEPT OVER THE FAR SCNTRL THAT WL MORE LIKELY ON THE ACYC SIDE OF THE VORT TRACK AND EXPERIENCE DOWNSLOPE FLOW IN THE WAKE OF THE LO. AS FOR TEMPS...GFS IS QUITE A BIT SLOWER PULLING LLVL COLD AIR INTO THE FA...SO WL RESTRICT MIX WITH SN OVER THE W HALF. ANY LINGERING PCPN OVER THE NRN TIER WL END MON EVNG AS SHRTWV/SFC LO PULL TO THE NE AND GIVE WAY TO RISING HGTS/MSLP. BUT ACTIVE WX PATTERN WL CONTINUE AS NEXT SHRTWV LIFTING OUT OF WRN TROF IS DUE TO LIFT FM THE SCNTRL PLAINS EARLY TUE AND INTO THE GRT LKS BY EARLY WED. ALL MODELS HAVE TRENDED FARTHER SE WITH THE TRACK OF THIS LOW...SO LOOKS LIKE ANOTHER WINTER STORM IS ON THE WAY AGAIN. PER NCEP GUIDANCE...TRENDED TOWARD THE GFS TO DETERMINE FCST DETAILS. ADJUSTED GOING FCST TO REFLECT HIER POPS OVER THE E WITH TREND TOWARD NEW TRACK...BUT MAINTAINED HIER POPS THAN MIGHT OTRW BE EXPECTED DUE TO CONTINUED UNCERTAINTY ON TRACK AS 00Z ECMWF IS A BIT FARTHER W. A FARTHER E TRACK ALSO IMPLIES MORE SN THAN FCST BEFORE. SO NEW FCST INDICATES AT LEAST A MIX WITH SN EVEN OVER THE SE ZNS BEGINNING TUE AFTN/EVNG WHEN DYNAMICS/DEEPER MSTR ARRIVE S-N. INTENSE UPWARD MOTION AND STRONG NNE FLOW TO THE W OF THE STORM TRACK LATE TUE NGT MAY BE ENUF TO CHG THE PCPN TO ALL SN EVEN OVER THE SE BEFORE STORM BEGINS TO PULL AWAY TO THE NE ON WED...WITH POPS DIMINISHING SW-NE. LATER SHIFTS WL LIKELY NEED TO ISSUE HEADLINES IF TRENDS WITH THIS NEXT STORM SYS CONTINUE. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... MID TO HIGH CLOUDS SHOULD BE THE RULE THROUGH THIS AFTN. WAVE OF SHOWERS OVR WESTERN WI COULD SKIRT CMX THIS EVENING. POTENTIAL OF MVFR DECK FORMING IN THE WAKE OF THE RAIN INTO THE OVERNIGHT HOURS. LATE TONIGHT...EXPECT BAND OF SHOWERS TO SWEEP ACROSS BOTH TAF SITES. EVEN A SLIM CHANCE FOR THUNDER AT SAW BUT KEPT OUT FOR NOW SINCE IT IS SUCH A LOW PROBABILITY. VSBY/CIGS NOT TOO LOW WITH THE RAIN...BUT ADDED MOISTURE AND FAVORABLE UPSLOPE WINDS WILL ALLOW CIGS/VSBY TO DROP TO LIFR AT CMX AFT 12Z. LOWER CIGS AND VSBY ALSO EXPECTED AT SAW BY MID MORNING ON MON. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A SERIES OF 3 LOW PRESSURE SYSTEMS WILL MOVE OVER THE GREAT LAKES REGION THROUGH THE PERIOD...WITH WINDS TO 30 KTS COMMON. FUNNELING NORTHEAST WINDS ACROSS THE FAR WESTERN LS ZONE SHOULD CREATE LOW 35KT GALES TODAY INTO EARLY EVENING...BEFORE WINDS BECOME MORE EASTERLY. THE SFC LOW TO OUR SE WILL MOVE TO WESTERN LAKE SUPERIOR BY MONDAY MORNING...AND SLIDE TO EASTERN ONTARIO WHILE FILLING TO 29.8 INCHES LATE MONDAY EVENING. IN ITS WAKE 30.1 INCH HIGH PRESSURE WILL MOVE OVER LAKE SUPERIOR. BY TUESDAY AFTERNOON 29.7 INCH LOW PRESSURE WILL ORGANIZING OVER THE SOUTHERN PLAINS. THIS LOW WILL SLIDE NORTHEAST...AND SHOULD RESIDE OVER UPPER MICHIGAN TO NORTHERN LAKE HURON BY WEDNESDAY MORNING...WITH ANOTHER POTENTIAL PERIOD OF GALES FOR W LS TUESDAY NIGHT. BY LATE THURSDAY...29.4 INCH LOW PRESSURE FROM THE CENTRAL PLAINS IS EXPECTED TO SLIDE TO WISCONSIN...WITH INCREASED WINDS EXPECTED ONCE AGAIN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING FROM 3 PM THIS AFTERNOON TO 10 PM EDT THIS EVENING FOR LSZ162. LAKE MICHIGAN...NONE. && $$ UPDATE...JLA DISCUSSION...KC AVIATION...JLA MARINE...KF mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1145 AM EDT SUN APR 6 2008 .UPDATE... LOT OF DRY AIR ON TAMDAR SOUNDING FM KSAW AND UPSTREAM SOUNDINGS AT GRB/DVN. SO...PCPN LOOKS LIKE IT WILL TAKE A BIT LONGER TO ARRIVE. LATEST NAM...RUC 13...AND LOCAL WRF-ARW INDICATE PCPN INTO FAR SW BTWN 21Z AND 03Z. BASED ON CLUSTER OF SHOWERS OVR NORTHEAST IA INTO SOUTHEAST MN WENT FOR 21Z. IN OUR AREA...SFC FRONT IS CURRENTLY BTWN ASX AND IWD AND THEN RUNS ACROSS NORTHERN UPR MI INTO LK SUPERIOR. NORTH OF THE FRONT...ESSENTIALLY LK SHORE AREAS OF FAR WEST ACROSS KEWEEANW TEMPS WILL STRUGGLE TO 40. SOUTH OF THE FRONT...PARTLY SUNNY SKIES AND DRY LOW TO MID LEVELS SHOULD ALLOW TEMPS TO RISE WELL INTO THE 50S AWAY FM INFLUENCE OF SE FLOW OFF LK MI. PCPN TONIGHT NOT AS FORMIDABLE ON LATEST MODEL RUNS. IN FACT...BASED ON QPF...CNTRL CWA MAY NOT SEE ANY PCPN UNTIL AFT 06Z. THINK VERY DRY AIR UPSTREAM AND SLOWER PROGRESSION OF SFC LOW/TROUGH MAY HAVE SOMETHING TO DO WITH THE TREND. MAY NEED TO MAKE SOME CHANGES TO CURRENT WX GRIDS FOR TONIGHT...BUT WILL HOLD OFF ATTM TO SEE HOW UPSTREAM PCPN PLAYS OUT THIS AFTN. UPDATED/PUBLISHED GRIDS AND ZFPMQT UPDATE ALREADY OUT. && .DISCUSSION (... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW POTENT SHRTWV MOVING EWD INTO THE NRN PLAINS WHILE ARCTIC VORTEX OVER SRN HUDSON BAY IS LIFTING TO THE NE. SFC COLD FNT ON THE SRN PERIPHERY OF COLD AIRMASS ASSOCIATED WITH THIS VORTEX HAS STALLED FM NRN WI TO BTWN MNM-IMT AND JUST N OF ESC/ISQ. 03Z SFC TEMP IS 52 AT MNM WITH 200 DEGREE WIND WHILE IMT IS 39 WITH A NNE WIND. BUT TREND IS FOR WINDS TO VEER MORE TO THE SSE...SO THIS FNT APPEARS TO BE RETURNING N AS A WARM FNT. 00Z GRB/APX/DVN RAOBS ARE QUITE DRY...SO NO PCPN AND JUST SOME SCT CLD COVER NOTED OVER THIS BNDRY IN THIS AREA. BUT SOME SHRA/ ISOLD TS NOTED CLOSE TO THE BNDRY FM THE WRN CWA TO DLH WHERE RUC/ NAM ANALYSIS INDICATE STEEP H7-5 LAPSE RATES AOA 7.5C/KM WITH DEEPER MSTR CLOSER TO SHARPER H8-7 FGEN IN RRQ OF H3 JET AXIS OVER ONTARIO ON SRN FLANK OF HUDSON BAY VORTEX. MAIN FCST CHALLENGES THIS PACKAGE REVOLVE ARND TIMING/IMPACT OF SHRTWV MOVING INTO THE NRN PLAINS. FOR TDAY...SHRTWV TO THE W IS FCST TO REACH SW MN BY 00Z MON...WITH ACCOMPANYING SFC LO NR MPX. THE NAM/GFS SHOW H85 FNT SHIFTING TO THE NW AS SHRTWV TAKES ON A MORE NEGATIVE TILT. THIS SHIFT IN THE POSITION OF THE H85 FNT SUGS THE DEEPER MSTR/WDSPRD PCPN ASSOCIATED WITH SHARPER H8-7 FGEN/RRQ OF UPR JET IN ONTARIO WL SHIFT TO THE NW AND REMAIN THERE THRU THE DAY. CONSIDERING SHIFT IN FRONTAL POSITION...DRYNESS OF THE AIRMASS TO THE S AND SE...AND TENDENCY FOR LARGER SCALE FLOW TO TURN MORE SSE...SUSPECT ANY SHRA NOW OVER THE WRN ZNS WL DIMINISH BY ARND FCST ISSUANCE IN LINE WITH RUC/NAM FCST. TDAY SHOULD FEATURE A GOOD DEAL OF SUNSHINE OVER THE SCNTRL AND ERN ZNS. SSE FLOW OFF LK MI WL HOLD DOWN DIURNAL TEMP RECOVERY FOR THE MOST PART (EXCEPT OVER THE WRN ZNS WHERE THAT FLOW WL DOWNSLOPE)... BUT MIXING TO H85 ON NAM FCST SDNGS STILL RESULTS IN TEMPS APRCHG 55. ALTHOUGH THE H85 FNT LOOKS TO SHIFT TO THE NW OF THE FA...THE BNDRY MAY GET HUNG UP OVER THE KEWEENAW DUE TO THE COOLING INFLUENCE OF LK SUP AND TENDENCY FOR THIS DENSER AIR TO RETARD RETREAT OF NEAR SFC COOL POOL. SO MUCH COOLER THERE. ALTHOUGH THE SSE FLOW WOULD BE A WARMING WIND FM IWD-ONTONAGON...MORE CLDS/SHRA CHCS WL ARRIVE THERE IN THE AFTN WITH APRCH OF DPVA/UPR DIFFLUENCE AHEAD OF SHRTWV AND WARM CONVEYOR BELT MSTR. MORE NEGATIVELY TILTED SHRTWV PROGGED TO MOVE INTO NW WI BY 12Z MON...WITH SFC LO REACHING THE WRN CWA. AS WARM CONVEYOR BELT MSTR PUSHES ACRS THE FA OVERNGT IN THE DPVA/UPR DIFFLUENCE AHEAD OF THE ARPCHG SHRTWV...WL GO WITH ARRIVAL OF CATEGORICAL/LIKELY POPS W-E BEFORE DRY SLOTTING AFT 06Z IMPACTS THE WI BORDER ZNS. LOWERED HIEST POPS AS THE CONVEYOR BELT WORKS E INTO DRY AIR. PCPN WL BE ENTIRELY IN THE FORM OF RA EXCEPT FOR PERHAPS THE IWD AREA LATE WITH ARRIVAL OF COLDER LLVL AIR IN CYC NLY FLOW LATE. BUT ANY SN WL BE INSIGNFICANT WITH DRY SLOTTING ALF. MIN TEMPS WL APRCH 32 OVER THE FAR W...BUT READINGS SHOULD REMAIN WELL ABV 32 ELSEWHERE. ON MON...NAM/GFS FCST SHRTWV/SFC LO TO REACH NE LK SUP BY 00Z TUE. THE GFS FCST TRACK IS A BIT FARTHER S. PER NCEP PREFERENCE...TRENDED AWAY FM THE NAM TOWARD THE GFS. LARGER SCALE PCPN ASSOCIATED WITH THE WARM CONVEYOR BELT MSTR SHOULD EXIT THE ERN ZNS DURING THE AFTN WITH ARRIVAL OF DRY SLOTTING. THE GFS SHOWS PATCH OF HIER MSTR ON CYC SIDE OF H5 VORT TRACK IMPACTING THE FA...WITH FAIRLY STEEP LAPSE RATES UNDER THE MSTR PATCH. WITH LLVL CYC FLOW...WL LINGER CHC POPS THRU THE DAY EXCEPT OVER THE FAR SCNTRL THAT WL MORE LIKELY ON THE ACYC SIDE OF THE VORT TRACK AND EXPERIENCE DOWNSLOPE FLOW IN THE WAKE OF THE LO. AS FOR TEMPS...GFS IS QUITE A BIT SLOWER PULLING LLVL COLD AIR INTO THE FA...SO WL RESTRICT MIX WITH SN OVER THE W HALF. ANY LINGERING PCPN OVER THE NRN TIER WL END MON EVNG AS SHRTWV/SFC LO PULL TO THE NE AND GIVE WAY TO RISING HGTS/MSLP. BUT ACTIVE WX PATTERN WL CONTINUE AS NEXT SHRTWV LIFTING OUT OF WRN TROF IS DUE TO LIFT FM THE SCNTRL PLAINS EARLY TUE AND INTO THE GRT LKS BY EARLY WED. ALL MODELS HAVE TRENDED FARTHER SE WITH THE TRACK OF THIS LOW...SO LOOKS LIKE ANOTHER WINTER STORM IS ON THE WAY AGAIN. PER NCEP GUIDANCE...TRENDED TOWARD THE GFS TO DETERMINE FCST DETAILS. ADJUSTED GOING FCST TO REFLECT HIER POPS OVER THE E WITH TREND TOWARD NEW TRACK...BUT MAINTAINED HIER POPS THAN MIGHT OTRW BE EXPECTED DUE TO CONTINUED UNCERTAINTY ON TRACK AS 00Z ECMWF IS A BIT FARTHER W. A FARTHER E TRACK ALSO IMPLIES MORE SN THAN FCST BEFORE. SO NEW FCST INDICATES AT LEAST A MIX WITH SN EVEN OVER THE SE ZNS BEGINNING TUE AFTN/EVNG WHEN DYNAMICS/DEEPER MSTR ARRIVE S-N. INTENSE UPWARD MOTION AND STRONG NNE FLOW TO THE W OF THE STORM TRACK LATE TUE NGT MAY BE ENUF TO CHG THE PCPN TO ALL SN EVEN OVER THE SE BEFORE STORM BEGINS TO PULL AWAY TO THE NE ON WED...WITH POPS DIMINISHING SW-NE. LATER SHIFTS WL LIKELY NEED TO ISSUE HEADLINES IF TRENDS WITH THIS NEXT STORM SYS CONTINUE. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... EASTERLY UPSLOPING WINDS WILL CONTINUE AT CMX. HOWEVER...WITH LITTLE IN THE WAY OF PRECIPITATION OVERNIGHT MVFR CEIGS ARE NOT ANTICIPATED. MID TO HIGH CLOUDS WILL BE THE RULE...STAYING VFR CEIGS AND VIS THROUGH 06Z SUNDAY AT BOTH SITES. AT THAT TIME THE SFC LOW TO OUR SOUTH WILL BE KNOCKING ON OUR DOOR...WITH -RA AND MVFR CEIGS FIGURED THROUGH 12Z. DEPENDING ON INTENSITY AND HOW MUCH LOW LEVEL MOISTURE STICKS AROUND...BR WITH LOWER VIS WILL BE POSSIBLE JUST AFTER 12Z. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A SERIES OF 3 LOW PRESSURE SYSTEMS WILL MOVE OVER THE GREAT LAKES REGION THROUGH THE PERIOD...WITH WINDS TO 30 KTS COMMON. FUNNELING NORTHEAST WINDS ACROSS THE FAR WESTERN LS ZONE SHOULD CREATE LOW 35KT GALES TODAY INTO EARLY EVENING...BEFORE WINDS BECOME MORE EASTERLY. THE SFC LOW TO OUR SE WILL MOVE TO WESTERN LAKE SUPERIOR BY MONDAY MORNING...AND SLIDE TO EASTERN ONTARIO WHILE FILLING TO 29.8 INCHES LATE MONDAY EVENING. IN ITS WAKE 30.1 INCH HIGH PRESSURE WILL MOVE OVER LAKE SUPERIOR. BY TUESDAY AFTERNOON 29.7 INCH LOW PRESSURE WILL ORGANIZING OVER THE SOUTHERN PLAINS. THIS LOW WILL SLIDE NORTHEAST...AND SHOULD RESIDE OVER UPPER MICHIGAN TO NORTHERN LAKE HURON BY WEDNESDAY MORNING...WITH ANOTHER POTENTIAL PERIOD OF GALES FOR W LS TUESDAY NIGHT. BY LATE THURSDAY...29.4 INCH LOW PRESSURE FROM THE CENTRAL PLAINS IS EXPECTED TO SLIDE TO WISCONSIN...WITH INCREASED WINDS EXPECTED ONCE AGAIN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING FROM 3 PM THIS AFTERNOON TO 10 PM EDT THIS EVENING FOR LSZ162. LAKE MICHIGAN...NONE. && $$ UPDATE...JLA DISCUSSION...KC AVIATION...KF MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 435 AM EDT SUN APR 6 2008 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW POTENT SHRTWV MOVING EWD INTO THE NRN PLAINS WHILE ARCTIC VORTEX OVER SRN HUDSON BAY IS LIFTING TO THE NE. SFC COLD FNT ON THE SRN PERIPHERY OF COLD AIRMASS ASSOCIATED WITH THIS VORTEX HAS STALLED FM NRN WI TO BTWN MNM-IMT AND JUST N OF ESC/ISQ. 03Z SFC TEMP IS 52 AT MNM WITH 200 DEGREE WIND WHILE IMT IS 39 WITH A NNE WIND. BUT TREND IS FOR WINDS TO VEER MORE TO THE SSE...SO THIS FNT APPEARS TO BE RETURNING N AS A WARM FNT. 00Z GRB/APX/DVN RAOBS ARE QUITE DRY...SO NO PCPN AND JUST SOME SCT CLD COVER NOTED OVER THIS BNDRY IN THIS AREA. BUT SOME SHRA/ ISOLD TS NOTED CLOSE TO THE BNDRY FM THE WRN CWA TO DLH WHERE RUC/ NAM ANALYSIS INDICATE STEEP H7-5 LAPSE RATES AOA 7.5C/KM WITH DEEPER MSTR CLOSER TO SHARPER H8-7 FGEN IN RRQ OF H3 JET AXIS OVER ONTARIO ON SRN FLANK OF HUDSON BAY VORTEX. MAIN FCST CHALLENGES THIS PACKAGE REVOLVE ARND TIMING/IMPACT OF SHRTWV MOVING INTO THE NRN PLAINS. FOR TDAY...SHRTWV TO THE W IS FCST TO REACH SW MN BY 00Z MON...WITH ACCOMPANYING SFC LO NR MPX. THE NAM/GFS SHOW H85 FNT SHIFTING TO THE NW AS SHRTWV TAKES ON A MORE NEGATIVE TILT. THIS SHIFT IN THE POSITION OF THE H85 FNT SUGS THE DEEPER MSTR/WDSPRD PCPN ASSOCIATED WITH SHARPER H8-7 FGEN/RRQ OF UPR JET IN ONTARIO WL SHIFT TO THE NW AND REMAIN THERE THRU THE DAY. CONSIDERING SHIFT IN FRONTAL POSITION...DRYNESS OF THE AIRMASS TO THE S AND SE...AND TENDENCY FOR LARGER SCALE FLOW TO TURN MORE SSE...SUSPECT ANY SHRA NOW OVER THE WRN ZNS WL DIMINISH BY ARND FCST ISSUANCE IN LINE WITH RUC/NAM FCST. TDAY SHOULD FEATURE A GOOD DEAL OF SUNSHINE OVER THE SCNTRL AND ERN ZNS. SSE FLOW OFF LK MI WL HOLD DOWN DIURNAL TEMP RECOVERY FOR THE MOST PART (EXCEPT OVER THE WRN ZNS WHERE THAT FLOW WL DOWNSLOPE)... BUT MIXING TO H85 ON NAM FCST SDNGS STILL RESULTS IN TEMPS APRCHG 55. ALTHOUGH THE H85 FNT LOOKS TO SHIFT TO THE NW OF THE FA...THE BNDRY MAY GET HUNG UP OVER THE KEWEENAW DUE TO THE COOLING INFLUENCE OF LK SUP AND TENDENCY FOR THIS DENSER AIR TO RETARD RETREAT OF NEAR SFC COOL POOL. SO MUCH COOLER THERE. ALTHOUGH THE SSE FLOW WOULD BE A WARMING WIND FM IWD-ONTONAGON...MORE CLDS/SHRA CHCS WL ARRIVE THERE IN THE AFTN WITH APRCH OF DPVA/UPR DIFFLUENCE AHEAD OF SHRTWV AND WARM CONVEYOR BELT MSTR. MORE NEGATIVELY TILTED SHRTWV PROGGED TO MOVE INTO NW WI BY 12Z MON...WITH SFC LO REACHING THE WRN CWA. AS WARM CONVEYOR BELT MSTR PUSHES ACRS THE FA OVERNGT IN THE DPVA/UPR DIFFLUENCE AHEAD OF THE ARPCHG SHRTWV...WL GO WITH ARRIVAL OF CATEGORICAL/LIKELY POPS W-E BEFORE DRY SLOTTING AFT 06Z IMPACTS THE WI BORDER ZNS. LOWERED HIEST POPS AS THE CONVEYOR BELT WORKS E INTO DRY AIR. PCPN WL BE ENTIRELY IN THE FORM OF RA EXCEPT FOR PERHAPS THE IWD AREA LATE WITH ARRIVAL OF COLDER LLVL AIR IN CYC NLY FLOW LATE. BUT ANY SN WL BE INSIGNFICANT WITH DRY SLOTTING ALF. MIN TEMPS WL APRCH 32 OVER THE FAR W...BUT READINGS SHOULD REMAIN WELL ABV 32 ELSEWHERE. ON MON...NAM/GFS FCST SHRTWV/SFC LO TO REACH NE LK SUP BY 00Z TUE. THE GFS FCST TRACK IS A BIT FARTHER S. PER NCEP PREFERENCE...TRENDED AWAY FM THE NAM TOWARD THE GFS. LARGER SCALE PCPN ASSOCIATED WITH THE WARM CONVEYOR BELT MSTR SHOULD EXIT THE ERN ZNS DURING THE AFTN WITH ARRIVAL OF DRY SLOTTING. THE GFS SHOWS PATCH OF HIER MSTR ON CYC SIDE OF H5 VORT TRACK IMPACTING THE FA...WITH FAIRLY STEEP LAPSE RATES UNDER THE MSTR PATCH. WITH LLVL CYC FLOW...WL LINGER CHC POPS THRU THE DAY EXCEPT OVER THE FAR SCNTRL THAT WL MORE LIKELY ON THE ACYC SIDE OF THE VORT TRACK AND EXPERIENCE DOWNSLOPE FLOW IN THE WAKE OF THE LO. AS FOR TEMPS...GFS IS QUITE A BIT SLOWER PULLING LLVL COLD AIR INTO THE FA...SO WL RESTRICT MIX WITH SN OVER THE W HALF. ANY LINGERING PCPN OVER THE NRN TIER WL END MON EVNG AS SHRTWV/SFC LO PULL TO THE NE AND GIVE WAY TO RISING HGTS/MSLP. BUT ACTIVE WX PATTERN WL CONTINUE AS NEXT SHRTWV LIFTING OUT OF WRN TROF IS DUE TO LIFT FM THE SCNTRL PLAINS EARLY TUE AND INTO THE GRT LKS BY EARLY WED. ALL MODELS HAVE TRENDED FARTHER SE WITH THE TRACK OF THIS LOW...SO LOOKS LIKE ANOTHER WINTER STORM IS ON THE WAY AGAIN. PER NCEP GUIDANCE...TRENDED TOWARD THE GFS TO DETERMINE FCST DETAILS. ADJUSTED GOING FCST TO REFLECT HIER POPS OVER THE E WITH TREND TOWARD NEW TRACK...BUT MAINTAINED HIER POPS THAN MIGHT OTRW BE EXPECTED DUE TO CONTINUED UNCERTAINTY ON TRACK AS 00Z ECMWF IS A BIT FARTHER W. A FARTHER E TRACK ALSO IMPLIES MORE SN THAN FCST BEFORE. SO NEW FCST INDICATES AT LEAST A MIX WITH SN EVEN OVER THE SE ZNS BEGINNING TUE AFTN/EVNG WHEN DYNAMICS/DEEPER MSTR ARRIVE S-N. INTENSE UPWARD MOTION AND STRONG NNE FLOW TO THE W OF THE STORM TRACK LATE TUE NGT MAY BE ENUF TO CHG THE PCPN TO ALL SN EVEN OVER THE SE BEFORE STORM BEGINS TO PULL AWAY TO THE NE ON WED...WITH POPS DIMINISHING SW-NE. LATER SHIFTS WL LIKELY NEED TO ISSUE HEADLINES IF TRENDS WITH THIS NEXT STORM SYS CONTINUE. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... AS OF 05Z...WARM FRONT EXTENDS FROM HAYWARD TO WATERSMEET AND IMT AND CONTINUES TO SLOWLY LIFT NORTH. PCPN HAS DEVELOPED NORTH OF THIS FRONT FROM NORTHERN MN INTO THE KEWEENAW. PCPN WILL MOVE COMPLETELY OUT OF CMX IN AN HOUR. THE QUESTION THEN IS WHAT FOLLOWS IN ITS WAKE AT CMX. EASTERLY WINDS UPSLOPING MOISTURE OFF LAKE SUPERIOR... COMBINED WITH THE PCPN THAT FELL...MAY BE ENOUGH TO GENERATE AN MVFR DECK. CURRENT FORECAST PLAN IS TO KEEP THE LOW CLOUD DECK IN THROUGH THE MORNING...THEN LIFT IT NORTH EARLY IN THE AFTERNOON. HOWEVER... WINDS JUST ABOVE THE SURFACE COULD GO SOUTHERLY QUICKER...PERHAPS BY 12Z...THEREFORE LOW CLOUD TRENDS WILL NEED TO BE MONITORED CLOSE AT CMX. AT SAW...DRY AIRMASS IN PLACE...BOTH ALONG AND SOUTH OF THE WARM FRONT...WILL KEEP VFR CONDITIONS GOING THROUGH THE DAY. WINDS LOOK TO GET GUSTY AT SAW DURING THE AFTERNOON...DUE TO A TIGHTENING OF THE PRESSURE GRADIENT SOUTH OF THE WARM FRONT AND DAYTIME HEATING MIXING DOWN HIGHER WINDS. FOR SUN NIGHT...LOW PRESSURE OVER THE EASTERN DAKOTAS IS EXPECTED TO APPROACH UPPER MI. SOME RAIN SHOWERS SHOULD FORM IMMEDIATELY AHEAD OF IT...BUT THIS PCPN WILL STAY WEST OF THE TAF SITES DURING THE CURRENT FORECAST PERIOD...THANKS TO THE DRY AIRMASS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A SERIES OF 3 LOW PRESSURE SYSTEMS WILL MOVE OVER THE GREAT LAKES REGION THROUGH THE PERIOD...WITH WINDS TO 30 KTS COMMON. FUNNELING NORTHEAST WINDS ACROSS THE FAR WESTERN LS ZONE SHOULD CREATE LOW 35KT GALES TODAY INTO EARLY EVENING...BEFORE WINDS BECOME MORE EASTERLY. THE SFC LOW TO OUR SE WILL MOVE TO WESTERN LAKE SUPERIOR BY MONDAY MORNING...AND SLIDE TO EASTERN ONTARIO WHILE FILLING TO 29.8 INCHES LATE MONDAY EVENING. IN ITS WAKE 30.1 INCH HIGH PRESSURE WILL MOVE OVER LAKE SUPERIOR. BY TUESDAY AFTERNOON 29.7 INCH LOW PRESSURE WILL ORGANIZING OVER THE SOUTHERN PLAINS. THIS LOW WILL SLIDE NORTHEAST...AND SHOULD RESIDE OVER UPPER MICHIGAN TO NORTHERN LAKE HURON BY WEDNESDAY MORNING...WITH ANOTHER POTENTIAL PERIOD OF GALES FOR W LS TUESDAY NIGHT. BY LATE THURSDAY...29.4 INCH LOW PRESSURE FROM THE CENTRAL PLAINS IS EXPECTED TO SLIDE TO WISCONSIN...WITH INCREASED WINDS EXPECTED ONCE AGAIN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING FROM 3 PM THIS AFTERNOON TO 10 PM EDT THIS EVENING FOR LSZ162. LAKE MICHIGAN...NONE. && $$ DISCUSSION...KC AVIATION...AJ MARINE...KF mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 1025 AM CDT MON APR 7 2008 .UPDATE...LET WARNING EXPIRE ACROSS MN THIS MORNING AS VERY HEAVY ACCUMULATING SNOW HAS ENDED. DEFORMATION AXIS STILL GENERATING SOME CONVECTIVE LOOK SNOW SHOWERS/SLEET ACROSS THE RANGE AND ARROWHEAD...SO WILL CONTINUE LIKELY POPS FOR TODAY WITH AN ADDITIONAL 2 INCHES POSSIBLE. ALSO MONITORING FGEN FORCED BAND ACROSS NW WI ATTM. REPORTS OF 1 INCH PER HOUR SNOWFALL RATE HAVE BEEN RECEIVED UNDERNEATH THIS BAND. FGEN FORCING DEPARTS THIS AFTERNOON...BUT WILL MONITOR CLOSELY FOR POSSIBLE ADVISORY. && .PREV DISCUSSION... /ISSUED 345 AM CDT MON APR 7 2008/ DISCUSSION...SHORT TERM CONCERN IS WINDING DOWN CURRENT STORM SYSTEM AND NEXT STORM SYSTEM LATE TUE INTO WED. LONG TERM CONCERN IS POSSIBLE SNOW SYSTEM LATE IN THE WEEK. SHORT TERM...CURRENT SURFACE ANALYSIS INDICATE MAIN AREA OF SNOW ACROSS NE MN WITH A NARROW BAND OF SNOW EXTENDING FROM HIB THROUGH GPZ TO BRD. THIS BAND IS ON THE BACKSIDE OF THE LOW MOVING THROUGH SOUTHERN MINNESOTA. MODELS ARE SIMILAR IN MOVING LOW THROUGH CENTRAL WI INTO THE MI UP BY THIS AFTERNOON. THE RUC/RADAR TRENDS INDICATE THERE WILL STILL BE SNOW FALLING ACROSS THE WARNING/ADVISORY AREA THROUGH 12Z. WILL KEEP THOSE HEADLINES IN EFFECT UNTIL 12Z. THE REST OF THE SNOW WILL STAY UP ACROSS THE ARROWHEAD INTO MIDMORNING. WILL MAKE CHANGES IN HEADLINES AREA LATE THIS MORNING IF NEEDED. ALL OF THE PRECIP PULLS OUT BY LATE THIS AFTERNOON AS LOW MOVES FURTHER INTO MICHIGAN AND DRIER AIR PUSHES INTO AREA. ALSO LOOKED AT THE RUC/BUFKIT...WILL WARNINGS AND ADVISORIES. LONG TERM...TUESDAY NIGHT THROUGH MONDAY... A STORM TRACK HAS SET UP FROM THE TEXAS PANHANDLE NORTHEASTWARD THROUGH THE CENTRAL GREAT LAKES. THE DEPARTING STORM WILL BE FOLLOWED BY A SECOND ONE OVER CHICAGO TUESDAY NIGHT. THIS STORM...SHEPHERDED BY A DIGGING TROUGH WITH A NEGATIVE TILT...WILL SPREAD LIGHT SNOW NORTHWESTWARD INTO OUR AREA TUESDAY NIGHT AND WEDNESDAY. THE LOW LEVEL DRY ADVECTION WILL GREATLY REDUCE PRECIPITATION AMOUNTS...ESPECIALLY NORTH AND WEST OF DULUTH. A THIRD DEEP STORM WILL MOVE OVER CHICAGO EARLY FRIDAY. LIGHT PRECIPITATION...AGAIN MOSTLY SNOW...WILL SPREAD ACROSS OUR AREA THURSDAY NIGHT THROUGH SATURDAY. AGAIN...THE COLD AND DRY AIR FEEDING IN FROM SOUTHERN CANADA WILL MITIGATE PRECIPITATION AMOUNTS...ESPECIALLY NORTH AND WEST OF DULUTH. AVIATION... IFR CONDS IN SNOW...ACRS NERN MN...AND RAIN...ALONG THE LKSHR AND NWRN WI...THIS MRNG WL SLOLY IPV TO MVFR DURG THE AFTN AND VFR FM NW TO SE THRUT TNGT. WE ANCPT VFR UNDER A FL 40 DECK TUE. && POINT TEMPS/POPS... DLH 34 24 39 25 / 70 10 20 40 INL 35 21 42 24 / 70 10 10 10 BRD 35 23 43 28 / 60 10 20 20 HYR 37 23 43 26 / 90 10 40 50 ASX 37 24 41 27 / 70 10 20 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ LILES mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 345 AM CDT MON APR 7 2008 .DISCUSSION...SHORT TERM CONCERN IS WINDING DOWN CURRENT STORM SYSTEM AND NEXT STORM SYSTEM LATE TUE INTO WED. LONG TERM CONCERN IS POSSIBLE SNOW SYSTEM LATE IN THE WEEK. .SHORT TERM...CURRENT SURFACE ANALYSIS INDICATE MAIN AREA OF SNOW ACROSS NE MN WITH A NARROW BAND OF SNOW EXTENDING FROM HIB THROUGH GPZ TO BRD. THIS BAND IS ON THE BACKSIDE OF THE LOW MOVING THROUGH SOUTHERN MINNESOTA. MODELS ARE SIMILAR IN MOVING LOW THROUGH CENTRAL WI INTO THE MI UP BY THIS AFTERNOON. THE RUC/RADAR TRENDS INDICATE THERE WILL STILL BE SNOW FALLING ACROSS THE WARNING/ADVISORY AREA THROUGH 12Z. WILL KEEP THOSE HEADLINES IN EFFECT UNTIL 12Z. THE REST OF THE SNOW WILL STAY UP ACROSS THE ARROWHEAD INTO MIDMORNING. WILL MAKE CHANGES IN HEADLINES AREA LATE THIS MORNING IF NEEDED. ALL OF THE PRECIP PULLS OUT BY LATE THIS AFTERNOON AS LOW MOVES FURTHER INTO MICHIGAN AND DRIER AIR PUSHES INTO AREA. ALSO LOOKED AT THE RUC/BUFKIT...WILL WARNINGS AND ADVISORIES. .LONG TERM...TUESDAY NIGHT THROUGH MONDAY... A STORM TRACK HAS SET UP FROM THE TEXAS PANHANDLE NORTHEASTWARD THROUGH THE CENTRAL GREAT LAKES. THE DEPARTING STORM WILL BE FOLLOWED BY A SECOND ONE OVER CHICAGO TUESDAY NIGHT. THIS STORM...SHEPHERDED BY A DIGGING TROUGH WITH A NEGATIVE TILT...WILL SPREAD LIGHT SNOW NORTHWESTWARD INTO OUR AREA TUESDAY NIGHT AND WEDNESDAY. THE LOW LEVEL DRY ADVECTION WILL GREATLY REDUCE PRECIPITATION AMOUNTS...ESPECIALLY NORTH AND WEST OF DULUTH. A THIRD DEEP STORM WILL MOVE OVER CHICAGO EARLY FRIDAY. LIGHT PRECIPITATION...AGAIN MOSTLY SNOW...WILL SPREAD ACROSS OUR AREA THURSDAY NIGHT THROUGH SATURDAY. AGAIN...THE COLD AND DRY AIR FEEDING IN FROM SOUTHERN CANADA WILL MITIGATE PRECIPITATION AMOUNTS...ESPECIALLY NORTH AND WEST OF DULUTH. .AVIATION... IFR CONDS IN SNOW...ACRS NERN MN...AND RAIN...ALONG THE LKSHR AND NWRN WI...THIS MRNG WL SLOLY IPV TO MVFR DURG THE AFTN AND VFR FM NW TO SE THRUT TNGT. WE ANCPT VFR UNDER A FL 40 DECK TUE. && POINT TEMPS/POPS... DLH 36 24 39 25 / 50 10 20 40 INL 37 21 42 24 / 60 10 10 30 BRD 38 23 43 28 / 70 10 20 20 HYR 38 23 43 26 / 40 10 40 50 ASX 38 24 41 27 / 50 10 20 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL 7 AM CDT THIS MORNING FOR CARLTON/SOUTHERN ST. LOUIS-CROW WING-SOUTHERN CASS. WINTER STORM WARNING UNTIL 10 AM CDT THIS MORNING FOR CENTRAL ST. LOUIS-KOOCHICHING-NORTHERN AITKIN-NORTHERN CASS- NORTHERN COOK/NORTHERN LAKE-NORTHERN ITASCA-NORTHERN ST. LOUIS-SOUTHERN COOK/LAKESHORE-SOUTHERN ITASCA-SOUTHERN LAKE/LAKESHORE. WINTER WEATHER ADVISORY UNTIL 7 AM CDT THIS MORNING FOR PINE- SOUTHERN AITKIN. WI...WINTER STORM WARNING UNTIL 7 AM CDT THIS MORNING FOR DOUGLAS. LS...SMALL CRAFT ADVISORY UNTIL 7 AM CDT THIS MORNING FOR LSZ121- LSZ140-LSZ141-LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147- LSZ148. $$ STEWART/04 mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 350 AM CDT SUN APR 6 2008 .SHORT TERM...TODAY THROUGH MONDAY...LOW CLOUDS HUNG IN ALL DAY SATURDAY AND HELD TEMPERATURES COOLER THAN EXPECTED. AM STILL DEALING WITH THESE LOW CLOUDS THIS MORNING WHICH HAVE BROKEN UP ACROSS THE CENTRAL AND EASTERN PORTIONS OF THE AREA. PATCHY DENSE FOG HAS DEVELOPED UNDER MOSTLY CLEAR SKIES WHERE THE BREAKS HAVE OCCURRED. PATCHY DENSE FOG AND SCATTERED LOW CLOUDS WILL CONTINUE THIS MORNING UNTIL A LITTLE AFTER SUNRISE. OUR AIRMASS IS RATHER DRY WITH PWS BELOW A HALF INCH AND A LITTLE MIXING IS EXPECTED TO DISSIPATE THE LOW CLOUDS AND FOG THIS MORNING. ELSE...WARMER AND QUIET WEATHER IS EXPECTED IN THE SHORT TERM. SATELLITE IMAGERY/RUC ANALYSIS SHOWS A WEAK SHORTWAVE OVER EAST TEXAS THAT WILL MOVE OVER OUR CWFA TODAY BUT HAVE LITTLE AFFECT ON DISCERNIBLE WEATHER. SURFACE ANALYSIS HAS A WEAK SOUTHWEST TO NORTHEAST ORIENTED RIDGE AXIS OVER OUR WESTERN COUNTIES AND PARISHES THAT WILL WEAKEN AND BECOME MORE EAST-WEST ORIENTED THROUGH MONDAY. THIS WILL RESULT IN MOSTLY LIGHT AND VARIABLE WINDS THROUGH THE SHORT TERM. UNDER SUNNY SKIES BY THIS AFTERNOON TEMPERATURES WILL RETURN CLOSER TO NORMAL AND TOP OUT IN THE MID TO UPPER 70S. MOSTLY CLEAR SKIES...LIGHT WINDS AND OUR DRY AIRMASS WILL ALLOW FOR GOOD RADIATIONAL COOLING TONIGHT. MONDAY MORNING LOWS WILL DIP BACK INTO THE UPPER 40S. OUR NEAR ZONAL FLOW ALOFT TODAY WILL BACK TO THE SOUTHWEST MONDAY. A QUICK WARM UP IS EXPECTED MONDAY MORNING AND AFTERNOON HIGHS WILL TOP OUT ABOVE NORMAL...AROUND 80 DEGREES. MAV GUIDANCE TEMPS WERE A LITTLE WARM IN THE DELTA TODAY BUT CLOSE AND GENERALLY ACCEPTED THROUGH THE PERIOD. /22/ .LONG TERM...MONDAY NIGHT THROUGH SUNDAY...WITH AN UPPER RIDGE TO THE EAST OF THE AREA...ALONG WITH HIGH PRESSURE AT THE SURFACE... NUDGED INTO THE REGION FROM THE NORTHEAST...LOOK FOR QUIET YET WARM WEATHER TO PERSIST THROUGH TUESDAY. CHANGES THOUGH WILL BEGIN OVER THE AREA STARTING LATE TUESDAY NIGHT...AND CONTINUE INTO THE FIRST PART OF THE WEEKEND. THE UPPER LEVEL RIDGE DOES HOLD ON OVER THE REGION WEDNESDAY FORCING AN UPPER LEVEL TROUGH...AND ASSOCIATED SURFACE LOW AND COLD FRONT... NORTHWARD TOWARD THE GREAT LAKES REGION. THE COLD FRONT APPROACHES THE AREA...BUT MODELS ARE NOW SHOWING IT STALL TO THE NORTHWEST OF THE CWA OVERNIGHT TUESDAY. THE BEST POPS DURING THIS TIME WILL BE ACROSS THE DELTA REGION DUE TO IT`S PROXIMITY TO THE FRONT...BUT MOST OF THE AREA WILL REMAIN DRY. THIS WEAK COLD FRONT WILL TRY TO PUSH INTO THE FORECAST AREA ON WEDNESDAY BRINGING BETTER RAIN CHANCES...BUT THE FRONT QUICKLY BEGINS TO LIFT BACK TO THE NORTH ON THURSDAY AS ANOTHER STORM SYSTEM BEGINS TO GET IT`S ACT TOGETHER OVER THE SOUTH CENTRAL UNITED STATES. A MUCH STRONG UPPER LEVEL LOW WILL DEEPEN AS IT MOVES ACROSS THE NATION`S MIDSECTION THURSDAY AFTERNOON. THIS WILL ALLOW A STRONG SURFACE LOW TO DEVELOP IN THE VICINITY OF THE TEXAS/OKLAHOMA PANHANDLES AND BEGIN PUSHING OUR WAY THURSDAY NIGHT. IT`S DURING THIS TIME THAT LOW LEVEL SOUTHERLY FLOW REALLY INCREASES BRINGING A SLUG OF GULF MOISTURE AND INSTABILITY UP INTO THE AREA AHEAD OF THE FRONT. BOTH THE GFS AND THE EUROPEAN HAVE SLOWED THIS SYSTEM DOWN A GOOD 12 HOURS. BUT BOTH ARE STILL IN PRETTY GOOD AGREEMENT WITH HOW THEY HANDLE THIS SYSTEM. WITH THAT SAID...WITH THE INCREASE IN MOISTURE AND INSTABILITY OVER THE AREA...COUPLED WITH THE AMPLE WIND SHEAR STILL BEING ADVERTISED BY THE MODELS...IT STILL APPEARS WE COULD SEE THE THREAT OF SOME STRONG TO SEVERE WEATHER ENTER INTO THE PICTURE LATE NEXT WEEK. AS USUAL WITH SYSTEMS THIS FAR OUT IN THE FUTURE... LATER MODEL RUNS AND FUTURE FORECASTS WILL CERTAINLY NEED TO MONITORED TO SEE EXACTLY HOW THIS ALL WILL PAN OUT. HIGH PRESSURE AT THE SURFACE BUILDS INTO THE AREA BEHIND THE FRONT SATURDAY EVENING. THEN FOR THE REMAINDER OF THE WEEKEND...LOOK FOR CLEARING CONDITIONS AND SOME SLIGHTLY COOLER DRIER AIR TO WORK IT`S WAY INTO THE REGION FOR NEXT SUNDAY. /19/ && .AVIATION...A BROKEN LAYER OF STRATUS BETWEEN 2500 AND 3000FT WAS STILL OVER THE AREA FROM SATURDAY RESULTING IN MVFR CEILINGS AT SOME SITES. UNDER THE BREAKS IN THE LAYER OF STRATUS...PATCHY DENSE FOG HAS DEVELOPED WITH LIFR VISIBILITIES BEING REPORTED. THE LAYER OF STRATUS IS EXPECTED TO CONTINUE TO SHRINK OVER THE AREA THIS MORNING WITH MORE OF THE AREA SEEING DENSE FOG DEVELOP. THE FOG IS EXPECTED TO BURN OFF RAPIDLY AFTER SUNRISE AND VFR CONDITIONS ARE EXPECTED TO PREVAIL AREAWIDE BY 15Z. VFR CONDITIONS ARE EXPECTED TO PREVAIL FROM 15Z UNTIL 09Z MONDAY WHEN VISIBILITIES ARE EXPECTED TO DROP BETWEEN 3 TO 5 STATUTE MILES AGAIN AND CONTINUE THROUGH 13Z MONDAY. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 77 48 82 58 / 0 0 0 0 MERIDIAN 78 47 82 55 / 0 0 0 0 VICKSBURG 77 50 82 56 / 0 0 0 0 HATTIESBURG 79 51 83 58 / 0 0 0 0 NATCHEZ 76 49 81 57 / 0 0 0 0 GREENVILLE 75 47 79 58 / 0 0 0 0 GREENWOOD 76 48 81 57 / 0 0 0 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM: 19 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 134 PM CDT SUN APR 6 2008 .DISCUSSION... ONLY MINOR CHANGES MADE TO THE GOING FORECAST AS MODEL GUIDANCE CONTINUES TO INDICATE A VERY ACTIVE AND WET WEEK AHEAD. WEAK SURFACE COLD FRONT WILL PASS ACROSS THE FORECAST AREA TONIGHT WITH LITTLE FAN FAIR AND STALL OUT JUST SOUTH OF THE CWA ON MONDAY. GIVEN EASTERLY FLOW ON MONDAY...TEMPERATURES WILL BE A DEGREE OR TWO COOLER THAN TODAY...BUT STILL SEASONABLE. MOISTURE WILL CONTINUE TO BUILD SOUTH OF THE FRONTAL BOUNDARY ON MONDAY AND AS THE LONGWAVE TROUGH ACROSS THE WESTERN CONUS EDGES EAST AND DEEPENS...LOW PRESSURE WILL DEVELOP TO THE LEE OF THE ROCKY MOUNTAINS. MONDAY NIGHT... STRONG AND QUITE BROAD LOW LEVEL JET DEVELOPS MONDAY NIGHT FROM THE SOUTHERN PLAINS TO THE LOWER MISSOURI VALLEY. AREA OF 900-800MB MOISTURE CONVERGENCE SLOWLY PUSHES NORTH ACROSS THE ENTIRE CWA MONDAY NIGHT AS THE FRONTAL BOUNDARY BEGINS TO LIFT NORTH. ELEVATED SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS FORCING AND CURRENT POPS ARE ALREADY CATEGORICAL FOR THIS TIME PERIOD. TUESDAY... BY TUESDAY MORNING EXPECT THE WARM FRONT TO BE ALIGNED FROM CHANUTE...KANSAS THROUGH THE LAKE OF THE OZARKS TO JUST SOUTH OF THE ST. LOUIS METROPOLITAN AREA. SPC HAS PLACED THE ENTIRE CWA IN A SLIGHT RISK AS SURFACE WAVE/LOW PRESSURE IS PROGGED TO MOVE NORTHEAST ALONG THE WARM FRONT FROM WEST-CENTRAL MISSOURI TO WEST CENTRAL ILLINOIS. THE INTENSITY AND COVERAGE OF SEVERE WEATHER WILL BE DETERMINED BY THE AMOUNT OF INSTABILITY THAT IS REALIZED IN THE WARM SECTOR AHEAD OF THE FROPA. TUESDAY NIGHT AND WEDNESDAY... FRONT SAGS SOUTH OF THE CWA OVERNIGHT TUESDAY AND WEDNESDAY WITH SLIGHTLY COOLER...BUT STILL SEASONABLE...TEMPERATURES EXPECTED AS EASTERLY FLOW DOMINATES. WEDNESDAY NIGHT THROUGH FRIDAY... STILL SOME UNCERTAINTY WITH THIS PERIOD AS ECWMF/GEM ARE MORE AMPLIFIED WITH NEXT TROF AND SURFACE WAVE WITH A TRACK THAT IS MORE FAVORABLE FOR SEVERE WEATHER...WHILE THE OPERATIONAL GFS TAKES A LESS AMPLIFIED SERIES OF SURFACE WAVES ALONG A NEARLY STATIONARY FRONT THAT REMAINS DRAPED ACROSS MISSOURI AND ILLINOIS...WHICH IS MORE CONDUCIVE TO HEAVY RAINFALL AND FLASH FLOODING. OBVIOUSLY TEMPERATURES DURING THIS PERIOD ARE HIGHLY DEPENDENT UPON FRONTAL POSITION. HAVE STAYED THE COURSE...AND FOLLOWED HPC GUIDANCE...WHICH SIDES CLOSELY WITH A MORE AMPLIFIED ECWMF SOLUTION. EXTENDED...SATURDAY AND SUNDAY NEXT WEEKEND LOOKS COOL AS NORTHWEST FLOW DOMINATES. SOME INDICATION BY MEDIUM RANGE MODEL GUIDANCE THAT THERE WILL BE A DISTURBANCE THAT DROPS DOWN ACROSS THE MIDWEST...PROVIDING AT LEAST A CHANCE OF RAIN ACROSS THE AREA. AT THIS POINT...WILL KEEP THE FORECAST DRY...AND LET LATER SHIFTS ADD POPS AS GUIDANCE COMES INTO AGREEMENT ON TIMING AND LOCATION OF THIS DISTRUBANCE. CVKING && .AVIATION... FOR THE 18Z TAFS...WEAK COLD FRONT WILL PASS THRU THE REGION OVERNIGHT. BAND OF SHOWERS (ISOLATED THUNDER IN MKC AREA THIS AM) CONTINUES TO MOV NE. THE EASTWARD MOVEMENT OF THE RAIN HAS NOTICEABLY SLOWED. RUC SHOWS SOME TEMP AND MOISTURE ADVETION IN THE AREA OF THE RAIN THEM MOVING IT MORE NE INTO IA. LOOKS LIKE THAT TREND WILL PREVAIL. HAVE PUT A TEMPO IN UIN FOR 6SM RW-...AND THAT WILL BE IT IN TERMS OF PRECIP FOR THIS BATCH OF TAFS. VFR TO PREVAIL ELSEWHERE WITH A WEAK WIND SHIFT TO THE WEST NORTHWEST. JPK && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 132 PM CDT SUN APR 6 2008 .DISCUSSION... ALTHO THERE IS STILL DISCREPENCY IN THE DETAILS...THE 00Z MODEL RUNS CERTAINLY CONTINUE TO SUPPORT THE GENL IDEA THAT UNSETTLED WX IS IN THE OFFING FOR OUR FA FOR MUCH OF THIS WEEK. THE GOOD NEWS IS THAT MAINLY TRANQUIL CONDS WILL HOLD FOR ANOTHER 36 HRS OR SO. 00Z WRF/NAM AND GFS STILL APR TO BE ON TRACK WITH WK CDFNT PASSING THRU AREA TNGT...ALBEIT JUST A BIT SLOWER THAN ERYR EXPECTED. WAA AHD OF CDFNT HAS BEEN GENERATING A FEW LGT SHWRS OVRNGT FROM NE KS INTO NW MO AND SW IA. DOUBT IF THIS PCPN AREA HOLDS TOGETHER LONG ENUF TO REACH OUR CWA...BUT CONTD WAA AND WK SHTWV ENERGY WITH LIMITED MSTR SHUD BE JUST ENUF TO CONT LO CHC POPS ALG AND AHD OF THE FNT...BGNG IN XTRM NW AREAS LT THIS AFTN AND PUSHING E ACR AREA TNGT. UNLIKE THE LAST FEW RUNS WHERE THE WRF/NAM WAS BEEFY WITH THE QPF THIS AFTN AND TNGT...00Z WRF/NAM RUNHAS BACKED OFF CONSIDERABLY AND NOW MIRRORS VRY LIGHT QPF SUGGESTED BY GFS AND ECMWF. CDFNT WL EXIT AREA BY 12Z MON AND BCM QSNTRY FROM OK INTO AR AS NRW SFC RDG WORKS FROM DKTAS TO MID MSVLY. STG WAA IS FCST TO DVLP IN ADV OF LEAD SHTWV OVR W PLAINS BY MON MRNG...WITH ISENTROPIC LIFT SPREADING E ACR PLAINS AND INTO W MO BY 00Z TUE AS RETURN FLOW INTENSIFIES AHD OF DVLPG SYS. SUSTAINED S FLO OVR S PLAINS AND LWR MSVLY FROM TDA INTO MON AFTN WL ALLOW FOR CONSIDERABLE MSTR INCR IN THE AMS TO OUR S...SO THINK THAT ONCE THE WAA KICKS IN ELEVATED SHWRS AND TSRA WL RPDLY DVLP AND SPRD E. MSTR AND LIFT ARE SO FAVORABLE THAT POPS HV BEEN INCRD ACR MUCH OF THE AREA...AND SPCLY FROM CNTRL MO INTO NE IL WHERE NOSE OF LLJ WL BE FOCUSING MUCH OF THE LIFT BY 12Z TUE. SFC LO IS FCST TO LIFT ACR AREA DURG THE DAY TUE...BUT MODELS DO DIFFER ON ITS EXACT TRACK. APPROX OF GUIDANCE MEAN FROM GFS...GFS ENSEMBLE...WRF/NAM... AND CANADIAN SUGGEST LOW WL MOVE FROM SW CORNER OF MO INTO UIN/PIA AREAS DURG THE DAY...ALTHO ECMWF IS STICKING WITH ITS ERYR TRACK OF TAKING LO INTO E IA BY 00Z WED...WHICH IS TREND ALSO SUPPORTED BY UKMET. EXACT TRACK OF THE LO WL HV A HUGE IMPACT ON TEMPS...AS WELL AS LOCATION AND SEVERITY OF ATTENDANT SVR WX. INITIALLY DURG THE PREDAWN HRS HAIL SHUD BE THE PRIMARY THRT WITH ELEVATED STORMS...WITH CNVTN GRADUALLY BCMG SFC OR NR SFC BASED DURG THE DAY AS THE WRM SECTOR SURGES N. WHILE THE SPECIFICS ARE NRLY IMPOSSIBLE TO PIN DOWN ATTM...LO LVL HELICITY AND BULK SHEAR CERTAINLY SUGGEST ITS GOING TO BE A BUSY DAY. PASSAGE OF CDFNT IN WAKE OF LO WL END TSRA FROM NW TO SE ACR AREA TUE NGT...WITH A BRIEF LULL EXPECTED ON WED BFR ROUND TWO DVLPS WED NGT AND THU...MIMICKING THE OVRALL TREND THAT IS EXPECTED MON NGT-TUE. DISCREPENCIES IN MODEL SOLNS BCM A BIT LARGER BY THIS TIME...BUT OVRALL THEY SUPPORT GOING FCST TRENDS SO NO MAJOR CHGS MADE TO THE WED-THU TIME FRAME. WL BE ISSUING AN ESF FOR THE UPCOMING WET WEATHER. IF QPF IS TAKEN VERBATIM THE MOST PROBLEMATIC TIME PD WOULD BE WITH ROUND TWO WED NGT-THU...WHICH FOCUSES THE HVIEST RAIN OVR WATERLOGGED S SECTIONS OF THE FA. HWVR...AMPLE MOISTURE COULD MEAN HVY RAINS AND ULTIMATELY SM WATER PROBLEMS IN N SECTIONS IN THE MON NGT-TUE TIME FRAME...WHILE IN THE WATERLOGGED S COUNTIES ANY RAIN IS ALMOST TOO MUCH AT THIS POINT. TRUETT && .AVIATION... FOR THE 18Z TAFS...WEAK COLD FRONT WILL PASS THRU THE REGION OVERNIGHT. BAND OF SHOWERS (ISOLATED THUNDER IN MKC AREA THIS AM) CONTINUES TO MOV NE. THE EASTWARD MOVEMENT OF THE RAIN HAS NOTICEABLY SLOWED. RUC SHOWS SOME TEMP AND MOISTURE ADVETION IN THE AREA OF THE RAIN THEM MOVING IT MORE NE INTO IA. LOOKS LIKE THAT TREND WILL PREVAIL. HAVE PUT A TEMPO IN UIN FOR 6SM RW-...AND THAT WILL BE IT IN TERMS OF PRECIP FOR THIS BATCH OF TAFS. VFR TO PREVAIL ELSEWHERE WITH A WEAK WIND SHIFT TO THE WEST NORTHWEST. JPK && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 835 PM MDT MON APR 7 2008 .SHORT TERM...VALID FOR TUE AND WED... UPDATE FOR ZONES AND AFP THIS EVENING. UPPER TROUGH OF LOW PRESSURE MOVING INTO WESTERN MONTANA THIS EVENING WHICH WILL KEEP UNSETTLED WEATHER OVER THE FORECAST AREA. HAVE EXTENDED POPS OVER THE SOUTHEAST ZONES THROUGH 06Z THIS EVENING AS PRECIPITATION CONTINUES TO DEVELOP ALONG A SURFACE CONVERGENCE ZONES. PRECIPITATION IS WIDELY SCATTERED AND WILL BE ENDING LATE THIS EVENING. 18Z MODELS DID NOT PICK UP ON SHORT WAVE MOVING ACROSS SW MT THIS EVENING. THE RUC/WRF 00Z RUNS HAVE FINALLY CAUGHT ON TO THIS WAVE AND PUSH IT INTO THE WESTERN ZONES BY LATE EVENING. HAVE RAISED POPS TO LIKELY IN SEVERAL LOCATIONS OVER THE WESTERN ZONES. LIVINGSTON HAS BEEN SNOWING THROUGH THE EVENING WITH VISIBILITY DOWN TO A MILE AT TIMES. SNOW THERE WILL DECREASE SHORTLY BUT WILL PICK UP AGAIN AFTER 06Z WITH OTHER SHORT WAVE OVER EASTERN WASHINGTON STATE ROTATING THROUGH. WARM GROUND TEMPERATURES WILL KEEP ACCUMULATING DOWN AND HAVE AN INCH OR LESS FOR LIVINGSTON. HAVE ADDED ISOLATED SNOW FOR BILLINGS OVERNIGHT WITH THIS SHORT WAVE MOVING INTO THE AREA AROUND 10Z. REMAINDER OF FORECAST IN GOOD SHAPE AND NO OTHER CHANGES MADE. RICHMOND .LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON... MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH MOST OF THE EXTENDED FORECAST. THEREFORE HAVE MADE VERY FEW CHANGES TO THE GRIDS THIS AFTERNOON. THURSDAY AND FRIDAY...NEGATIVELY TILTED TROUGH WILL AFFECT THE AREA THROUGH FRIDAY AFTERNOON. THE BEST CHANCES FOR PRECIPITATION WILL BE ACROSS THE EASTERN THIRD OF THE FORECAST AREA ON THURSDAY. LOOKS TO BE RELATIVELY UNSTABLE. WOULD NOT BE SURPRISED TO SEE SOME LIGHTNING ACROSS THE SOUTHEAST BUT LOOKS MARGINAL AT THIS TIME SO LEFT IT OUT OF THE GRIDS FOR NOW. LATER ON FRIDAY A HIGHLY AMPLIFIED RIDGE BEGINS TO MOVE INTO MONTANA. THIS WILL DRY THINGS OUT AND BEGIN A WARMING TREND. SATURDAY THROUGH MONDAY...STRONG UPPER LEVEL RIDGE DOMINATES THE AREA. TEMPERATURES WILL BE ABOVE NORMAL AND CONDITIONS WILL REMAIN DRY. THE MODELS DO BEGIN TO DIVERGE ON SUNDAY WITH THE GFS HOLDING ON TO THE UPPER LEVEL RIDGE AND THE ECMWF CREATING MORE FLAT NORTHWEST FLOW OVER THE AREA. EITHER WAY...BOTH MODELS AGREE THAT IT WILL BE WARM ACROSS THE AREA THROUGH MONDAY WITH 850 MB TEMPS AROUND 12 TO 15C. STOPPKOTTE && .AVIATION... A WEAK DISTURBANCE WILL ENHANCE AN AREA OF SNOW SHOWERS WEST OF BILLINGS THIS EVENING. MVFR TO IFR EXPECTED IN THIS AREA...WHICH INCLUDES LVM AND 3HT. SNOW SHOWERS MAY MAKE IT AS FAR WEST AS BIL- SHR BETWEEN 06-12Z. OTHERWISE SCATTERED -SHRASN BETWEEN BIL AND MLS SHOULD DIMINISH BEFORE 06Z. SCATTERED RAIN OR SNOW SHOWERS ON TAP AGAIN FOR TOMORROW ACROSS THE AREA...ESPECIALLY DURING THE AFTERNOON. LOCALIZED MVFR IN THE HEAVIER SHOWERS TOMORROW...AND MOUNTAINS WILL BE OBSCURED AT TIMES. JKL && .PRELIMINARY POINT TEMP/POPS... TUE WED THU FRI SAT SUN MON ----------------------------------------------------------- BIL 032/053 033/052 031/052 031/057 036/062 036/062 037/058 33/O 23/W 42/W 21/B 11/B 11/B 11/B LVM 027/047 027/048 028/049 026/053 028/060 033/058 031/056 62/S 24/W 33/W 21/B 11/N 11/B 12/W HDN 032/055 033/057 031/054 031/058 034/065 032/064 037/062 33/O 23/W 43/W 21/B 11/B 10/B 11/B MLS 030/055 031/056 030/053 029/056 034/063 033/063 037/060 22/O 23/W 53/W 21/B 11/B 10/B 11/B 4BQ 030/052 030/055 029/051 029/055 034/063 033/064 035/056 23/O 24/W 43/W 31/B 11/B 11/B 11/B BHK 024/054 026/052 026/046 027/052 033/060 033/062 032/059 22/O 23/W 53/W 21/B 11/B 10/B 11/B SHR 030/049 028/050 026/048 024/052 028/060 027/061 031/058 43/O 24/W 43/W 31/B 11/B 11/B 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS mt AREA FORECAST DISCUSSION...CORRECTED FOR TIME NATIONAL WEATHER SERVICE GRAND FORKS ND 320 AM CDT SUN APR 6 2008 .DISCUSSION... FORECAST CHALLENGE CONCERN ONGOING HEADLINES...SNOW AMOUNTS/COVERAGE AND TEMPERATURES. MODELS IN FAIR AGREEMENT THROUGH PERIOD AND WILL USE BLEND FOR FORECAST. MID LEVEL CIRCULATION OVER WESTERN SD TO SHIFT EAST ACROSS SD DURING DAY. COMBINATION OF WAVE PASSAGE AND RIGHT ENTRANCE REGION OF UPPER JET PROVIDING ENHANCED UPPER LEVEL DIVERGENCE OVER BAROCLINIC ZONE ACROSS SE FA. BATTLE BETWEEN DRY NE FLOW AND STRONG ISENTROPIC LIFT WILL LIKELY RESULT IN SHARP CUTOFF BETWEEN NO AND HEAVY SNOWFALL TODAY. CURRENTLY MOISTURE BOUNDARY EXTENDING FROM NEAR LISBON TO FAR...FSE AND INL WHERE LOW TEEN DEWPOINTS TRANSITION TO NEAR 30 DEWPOINTS OVER A FEW MILES. SO EXPECT HEAVY SNOWFALL SE OF THIS BOUNDARY WITH NARROW ZONE AS A BUFFER BETWEEN MODEST AND HEAVIER AMOUNTS. RUC LOOKS TO HAVE BEST HANDLE ON THIS FEATURE AND LIFTS BOUNDARY ONLY SLIGHTLY N/NW DURING DAY. AS A RESULT AM NOT EXPECTING HEAVY SNOW BAND TO SHIFT MUCH DURING DAY. SHOWALTER INDICES INCREASE OVERNIGHT AND LOW LEVEL JET SHIFTS EAST SO THUNDER SNOW SHOULD DIMINISH HOWEVER WITH PRECIPITABLE H20 VALUES FROM .50 TO .75 PLENTY OF MOISTURE AVAILABLE. HATS OFF TO EVENING SHIFT WHICH DID AN EXCELLENT JOB IN LAYING OUT WARNING/ADVISORY AREAS AND ONLY CHANGES WILL BE MINOR TIMING OF HEADLINE START TIMES OVER FAR SE FA TO COINCIDE WITH FORECAST ISSUANCE AND TO UP SNOW AMOUNTS OVER PORTIONS OF WARNING AREA AS ALREADY GETTING REPORTS OF 6 INCHES NEAR PKD. BASED ON CURRENT AND EXPECTED RADAR TRENDS WILL ALSO CANCEL NW PORTION ADVISORY AREA WHICH NOT SEE SIGNIFICANT SNOWFALL. WILL BE TRIMMING POPS ACROSS NW HALF OF FA AS DRIER AIR/HIGH PRESSURE WRAPS AROUND SURFACE LOW CURRENTLY OVER SE SD. WILL EVEN LIKELY SEE SOLAR OVER FAR NW TODAY SO WARMEST TEMPERATURES OVER THIS AREA. SYSTEM PULLS AWAY TONIGHT FOR GRADUALLY DIMINISHING SNOWFALL HOWEVER FAR SE WILL REMAIN UNDER THE GUN INTO THE EVENING HOURS BEFORE DEFORMATION ZONE PCPN BAND SHIFTS SE. WILL KEEP HEADLINES GOING INTO EVENING AND LET LATER SHIFTS TWEAK AS NEEDED. WILL LIKELY SEE SNOW ACCUMULATIONS IN EXCESS OF A FOOT OVER SOME AREAS. SURFACE HIGH BUILDS INTO REMAINDER OF FA MONDAY AND WITH DRY COLUMN/MODERATING THERMAL PROFILE TEMPERATURES SHOULD BE ABLE TO RECOVER. WILL KEEP COOLEST TEMPERATURES OVER ANTICIPATED SNOWFIELD. SURFACE HIGH PRESSURE REMAINS IN CONTROL THROUGH MIDWEEK FOR DRY PERIOD AND SEASONAL TEMPERATURES. WESTERN TROUGH SHIFTS EAST LATE IN WORK WEEK HOWEVER RETURN FLOW AROUND HIGH MAY LIMIT PCPN POTENTIAL. FOR NOW WILL HOLD ON TO LOW POPS IN LATER PERIODS HOWEVER CONFIDENCE NOT HIGH. ONLY MINOR CHANGES PLANNED TO LATER PERIODS. && .AVIATION... WILL BE SHARP CUTOFF BETWEEN IFR CIGS/VSBY IN S. LOWEST CIGS WILL BE SOUTH AND EAST OF A LINE FROM LISBON TO FAR TO BJI TRANSITIONING FAIRLY QUICKLY TO VFR OVER REMINDER OF FA. EXPECT CONDITIONS TO CONTINUE MOST OF DAY WITH IMPROVEMENT FROM W TO E LATER IN AFTERNOON. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NDZ039- 049-052. WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR NDZ053. MN...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MNZ002- 003-009-015-016. WINTER WEATHER ADVISORY UNTIL 10 PM CDT THIS EVENING FOR MNZ040. WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR MNZ017- 022>024-027-028. WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR MNZ029>032. && $$ VOELKER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1111 AM CDT MON APR 7 2008 .DISCUSSION... MODIFIED 1ST/2ND PERIOD DEWPOINTS/WINDS/TEMPS BASED ON INGESTED OBSERVATIONS AND LATEST RUC FORECASTS. UNCERTAINTY CONTINUES ON EVOLUTION OF DRY LINE AND WARM FRONT STRUCTURES AND RESULTING LOWER-LEVEL WIND FIELDS/CONVERGENCE. IF WE CAN GET STORMS GOING IN THE WARM SECTOR... LOWER-LEVEL WIND SHEAR FORECAST ARE SOME OF THE MORE IMPRESSIVE THAT WE HAVE SEEN THIS YOUNG SPRING SEASON. HOWEVER...QUALITY/TIMING OF MOISTURE REGIME IN QUESTION. HAZARDOUS WEATHER GRAPHICS/OUTLOOKS UPDATED TO RAISE CONCERNS AND AWARENESS. GREATEST CONCERN FOR SEVERE WILL BE SOUTHWEST/WEST- CENTRAL OKLAHOMA EAST-NORTHEAST THROUGH CENTRAL OKLAHOMA TOWARD AND AFTER 5 PM. && .PREV DISCUSSION... /ISSUED 312 AM CDT MON APR 7 2008/ DISCUSSION... BOUNDARY LAYER MOISTURE WILL MOVE QUICKLY NORTH THIS MORNING INTO OKLAHOMA AS A WARM FRONT NEAR THE RED RIVER MOVES INTO NORTHERN OKLAHOMA BY EARLY AFTERNOON. LOWER LEVEL MOISTURE WILL DEEPEN BY THE TIME ALSO. THE DRY LINE IS EXPECTED TO APPROACH SOUTHWEST OKLAHOMA AND ADJACENT PARTS OF NORTH TEXAS BY LATE AFTERNOON, WHEN AND WHERE THUNDERSTORMS MAY FORM FIRST. A SURFACE LOW PRESSURE AT THE INTERSECTION OF THE TWO FRONTS WILL BE A FURTHER FOCUS FOR THUNDERSTORMS OVER WESTERN OKLAHOMA THIS EVENING. THE FRONT SHOULD BE ACROSS SOUTHEAST OKLAHOMA BY MIDDAY TUESDAY, HAVING GIVEN A GOOD CHANCE FOR RAIN, ESPECIALLY IN NORTH CENTRAL OKLAHOMA NEAR AND NORTH OF THE WARM FRONT OVERNIGHT. WEDNESDAY WILL BE A CLOUDY AND COOL DAY. THE PREVIOUS FRONT WILL HAVE BROUGHT ONLY A SHALLOW AIRMASS, SO WARM ADVECTION ABOVE THE FRONTAL ZONE IS EXPECTED WEDNESDAY MORNING FOR MORE GENERAL SHOWERS AND THUNDERSTORMS IN SOUTHERN OKLAHOMA. THE STRONGER LONG WAVE TROUGH MAY SEND SEVERAL WEAKER UPPER FEATURES ACROSS THIS AIRMASS WEDNESDAY NIGHT AND THURSDAY. AN ASSOCIATED SURFACE TROUGH/FRONT ACROSS THE SOUTHEAST HALF OF OKLAHOMA MAY LEAD TO HEAVY RAINFALL THERE. ONCE THIS SYSTEM MOVES EAST LATER THURSDAY, DRIER AND MILD WEATHER IS EXPECTED INTO THE WEEKEND UNDER THE INFLUENCE OF NORTHWEST WINDS THROUGH A DEEP LAYER OF THE ATMOSPHERE. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 69 55 61 41 / 20 60 30 10 HOBART OK 80 53 64 39 / 20 30 20 10 WICHITA FALLS TX 83 60 73 46 / 20 30 30 30 GAGE OK 63 38 59 31 / 20 50 10 10 PONCA CITY OK 59 50 60 39 / 20 80 40 0 DURANT OK 82 62 71 52 / 10 30 60 50 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 11/30 ok AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1256 PM CDT SUN APR 6 2008 .UPDATE... UPDATED TO EXTEND THE WINTER STORM WARNING THROUGH LATE AFTERNOON ACROSS THE NORTHWESTERN ZONES. ALSO ADDED STANLEY AND HUGHES COUNTIES INTO THE WINTER WEATHER ADVISORY. NO OTHER CHANGES MADE AT THIS TIME. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH TUESDAY FORECAST CHALLENGES IS SNOWFALL AMOUNTS AND TIMING THE CHANGE OF PRECIPITATION TYPE AS THE DAY WEARS ON. CURRENTLY...A VIGOROUS EARLY SPRING WINTER STORM SYSTEM IS WORKING ITS WAY ACROSS SOUTH DAKOTA. THE TROWAL/DEFORMATION ZONE ON THIS LOW IS QUITE EVIDENT IN SATELLITE/RADAR IMAGERY ACROSS WESTERN SOUTH DAKOTA AND EXTREME SOUTH CENTRAL NORTH DAKOTA...AND IS SPREADING SNOW EASTWARD ACROSS THIS FORECAST AREA /IN PARTICULAR...NORTH CENTRAL SOUTH DAKOTA/. LIGHTNING HAS BEEN DETECTED IN ASSOCIATION WITH SNOW FALLING THIS MORNING OVER CENTRAL SOUTH DAKOTA...AND AN IMPRESSIVE BAND OF 30 TO 40 DBZ ECHOES HAS DEVELOPED ACROSS NORTH CENTRAL SOUTH DAKOTA WITH A FEW REPORTS FROM LAW ENFORCEMENT EARLY THIS MORNING INDICATING SLICK ROADS AND LIGHT SNOW ACCUMULATIONS...THUS FAR...FROM A COMBINATION OF SNOW AND SLEET. TO COMPLICATE THINGS FURTHER...SURFACE TO 925HPA CAA IS UNDERCUTTING THE STRONG SURGE OF WARM/MOIST AIR FROM THE SOUTH THIS MORNING...CREATING /BASED OFF REAL-TIME RUC- CASTING/ AN AREA SUPPORTIVE OF FREEZING RAIN AND SLEET. SURFACE TO 925HPA TEMPERATURES ARE COOLING FROM NORTH TO SOUTH AND FALLING BELOW THE FREEZING MARK ACROSS PRETTY MUCH EVERYWHERE BUT THE FAR EASTERN ZONES THIS MORNING. MEANWHILE 850HPA TEMPS ARE STILL ANYWHERE FROM 1 TO 5 DEGREES C ABOVE FREEZING ON TOP OF THIS COLDER LAYER LOWER DOWN. THIS POTENTIAL CORRIDOR OF FREEZING RAIN AND SLEET...MIXING WITH AND CHANGING OVER TO SNOW WILL PRECEDE THE HEAVY WET TROWAL-FORCED SNOW BAND CHASING IT FROM WEST TO EAST ACROSS THE FORECAST AREA TODAY. BY NOON CDT...THE THREAT FOR FREEZING PRECIPITATION IS PRETTY MUCH RELEGATED TO MINNESOTA...WITH JUST A HEAVY WET BAND OF SNOW WORKING INTO NORTHEAST SOUTH DAKOTA AND PERSISTING THERE INTO THE EARLY EVENING HOURS. WITH WORD COMING THIS MORNING FROM MY WESTERN FORECAST NEIGHBOR THAT THEY HAD ALREADY RECEIVED REPORTS OF 5 TO 8 INCHES OF SNOWFALL IN THEIR AREA IN A SPAN OF LESS THEN 6 HOURS...THINKING THAT OUR WINTER WEATHER ADVISORY FOR A MIXTURE OF PRECIPITATION TYPES AND 2 TO 5 INCHES OF SNOWFALL MAY NOT BE ENOUGH TO COVER THE SNOW TOTALS ACROSS NORTH CENTRAL SOUTH DAKOTA THAT ARE CURRENTLY PILING UP. ONCE THIS LOW DEPARTS SOUTH DAKOTA THIS EVENING...HIGH PRESSURE AT THE SURFACE AND ALOFT WORKS INTO THE FORECAST AREA...CLEARING AND DRYING THINGS OUT THROUGH PRETTY MUCH THE REMAINDER OF THE SHORT TERM FORECAST. THE 00Z GFS AND ECMWF MODELS CONTINUE TO TREND THE BROAD UPPER LEVEL TROF OF LOW PRESSURE FURTHER SOUTH AND EAST MONDAY NIGHT THROUGH TUESDAY NIGHT. SO...CONTINUED TO SHAVE MORE OFF OF THE POPS/WX FORECAST FOR SAID TIME FRAME. MODEL THERMAL PROGS STILL LEAVE MUCH TO BE DESIRED FOR NAILING DOWN THE PRECIPITATION TYPE WITH THIS RATHER WEAK/ILL-DEFINED SYSTEM...SO CONTINUED A FORECAST OF RAIN OR SNOW CHANCES ACROSS MAINLY THE SOUTHERN HALF OF THE FORECAST AREA. NO SIGNIFICANT CHANGES TO THE GOING MAX/MIN T FORECAST IN THE SHORT TERM. WILL HAVE TO SEE WHAT SHAKES OUT OF THE ONGOING SNOW EVENT IN ORDER TO BETTER DEFINE MAX/MIN T FORECAST FOR MONDAY AND TUESDAY. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY BIGGEST CHALLENGE IN THE EXTENDED STILL DEALS WITH PCPN CHANCES MID WEEK AND TOWARD THE END OF THE WEEK. MODELS ARE NOW TAKING THE MID WEEK SYSTEM A BIT FURTHER SOUTH...WITH SFC HIGH PRESSURE NOW BUILDING SOUTH INTO THE EASTERN DAKOTAS 00Z WED THROUGH 12Z WED. THETA SURFACES INDICATE DOWNGLIDE TAKING PLACE...SO SAW NO REASON TO LEAVE IN MENTION OF PCPN. ENSEMBLE GUIDANCE HAS ALSO FALLEN TO LESS THAN SLIGHT CHC POPS. ATTENTION THEN TURNS TOWARD THURSDAY AFTERNOON/FRIDAY SYSTEM. BOTH GFS AND EC ARE NOW LIFTING THE SFC LOW NORTHWARD INTO THE PLAINS BY 12Z FRIDAY. THE LATEST 00Z EC IS NOW PUSHING THE SFC LOW A BIT FURTHER TO THE EAST COMPARED TO THE PREVIOUS 12Z RUN...BUT IT STILL APPEARS THAT PCPN AT LEAST DESERVES A CHC MENTION THURSDAY NIGHT INTO FRIDAY. 00Z GFS SHOWS WELL DEFINED 7H TROWAL ACROSS NERN SD BY 12Z FRIDAY...WITH 290K SPEC HUMIDITIES NEARING 3G/KG BY 12Z FRIDAY. WITH MODELS STILL TRYING TO NAIL DOWN EXACT PLACEMENT OF THE OVERALL FEATURES...AM COMFORTABLE WITH LOW CHC POPS UNTIL THINGS BECOME A BIT MORE CERTAIN. WITH HIGH PRESSURE NOW NOSING DOWN INTO CWA FOR WEDNESDAY PERIOD...HAVE NUDGED UP WEDNESDAY FCST HIGHS A DEGREE OR THREE...ESPECIALLY ACROSS THE NE WHERE AMPLE SUNSHINE WILL SUPPORT INCREASED HIGHS. REMAINDER OF TEMP GRIDS PRETTY MUCH LEFT WHAT WAS INHERITED. && .AVIATION... CIGS ACROSS THE CWA WILL BE MAINLY IN THE LIFR TO IFR CATEGORIES BETWEEN 100 AND 800 FEET THROUGH THE AFTERNOON. THE EXCEPTION WILL BE OVER THE SOUTHWESTERN CWA NEAR KPIR...WHERE HIGH IFR TO MVFR CIGS ARE EXPECTED BETWEEN 800 AND 1800 FEET. SNOW WILL CONTINUE ACROSS THE NORTHWESTERN AND CENTRAL PARTS OF THE CWA...REDUCING VSBYS INTO THE LIFR/IFR CATEGORIES BETWEEN 1/4 MILE AND 2 MILES...MAINLY AFFECTING KMBG AND KABR. THE AREA OF SNOW WILL SLIDE EAST LATER THIS AFTERNOON AND THIS EVENING...AFFECTING KATY AROUND OR SHORTLY AFTER 20Z. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER STORM WARNING UNTIL 4 PM CDT /3 PM MDT/ THIS AFTERNOON FOR CAMPBELL-CORSON-DEWEY-POTTER-WALWORTH. WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR CODINGTON- GRANT-HAMLIN-ROBERTS. WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR BROWN-CLARK- DAY-EDMUNDS-FAULK-MARSHALL-MCPHERSON-SPINK. WINTER WEATHER ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR HAND-HUGHES-HYDE-STANLEY-SULLY. MN...WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR BIG STONE- TRAVERSE. && $$ UPDATE...PARKIN SHORT TERM...DORN LONG TERM...HINTZ AVIATION...PARKIN WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1144 AM CDT SUN APR 6 2008 .UPDATE... NO MAJOR UPDATES MADE TO THE FORECAST AT THIS TIME. BROAD AREA OF SNOW CONTINUES TO SPIN OVER THE NORTHWESTERN AND CENTRAL PART OF THE CWA. ALSO SEEING A LINE OF SHOWERS/FREEZING RAIN TRACKING NORTHWARD EAST OF INTERSTATE 29. CURRENT WINTER STORM WARNING SET TO EXPIRE IN A COUPLE OF HOURS IN THE NORTHWEST. WILL CONTINUE TO MONITOR THAT AREA AND MAY NEED TO EXTEND THE WARNING. NO CHANGES MADE TO TEMPERATURES OR WINDS. NEW AVIATION DISCUSSION BELOW. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH TUESDAY FORECAST CHALLENGES IS SNOWFALL AMOUNTS AND TIMING THE CHANGE OF PRECIPITATION TYPE AS THE DAY WEARS ON. CURRENTLY...A VIGOROUS EARLY SPRING WINTER STORM SYSTEM IS WORKING ITS WAY ACROSS SOUTH DAKOTA. THE TROWAL/DEFORMATION ZONE ON THIS LOW IS QUITE EVIDENT IN SATELLITE/RADAR IMAGERY ACROSS WESTERN SOUTH DAKOTA AND EXTREME SOUTH CENTRAL NORTH DAKOTA...AND IS SPREADING SNOW EASTWARD ACROSS THIS FORECAST AREA /IN PARTICULAR...NORTH CENTRAL SOUTH DAKOTA/. LIGHTNING HAS BEEN DETECTED IN ASSOCIATION WITH SNOW FALLING THIS MORNING OVER CENTRAL SOUTH DAKOTA...AND AN IMPRESSIVE BAND OF 30 TO 40 DBZ ECHOES HAS DEVELOPED ACROSS NORTH CENTRAL SOUTH DAKOTA WITH A FEW REPORTS FROM LAW ENFORCEMENT EARLY THIS MORNING INDICATING SLICK ROADS AND LIGHT SNOW ACCUMULATIONS...THUS FAR...FROM A COMBINATION OF SNOW AND SLEET. TO COMPLICATE THINGS FURTHER...SURFACE TO 925HPA CAA IS UNDERCUTTING THE STRONG SURGE OF WARM/MOIST AIR FROM THE SOUTH THIS MORNING...CREATING /BASED OFF REAL-TIME RUC- CASTING/ AN AREA SUPPORTIVE OF FREEZING RAIN AND SLEET. SURFACE TO 925HPA TEMPERATURES ARE COOLING FROM NORTH TO SOUTH AND FALLING BELOW THE FREEZING MARK ACROSS PRETTY MUCH EVERYWHERE BUT THE FAR EASTERN ZONES THIS MORNING. MEANWHILE 850HPA TEMPS ARE STILL ANYWHERE FROM 1 TO 5 DEGREES C ABOVE FREEZING ON TOP OF THIS COLDER LAYER LOWER DOWN. THIS POTENTIAL CORRIDOR OF FREEZING RAIN AND SLEET...MIXING WITH AND CHANGING OVER TO SNOW WILL PRECEDE THE HEAVY WET TROWAL-FORCED SNOW BAND CHASING IT FROM WEST TO EAST ACROSS THE FORECAST AREA TODAY. BY NOON CDT...THE THREAT FOR FREEZING PRECIPITATION IS PRETTY MUCH RELEGATED TO MINNESOTA...WITH JUST A HEAVY WET BAND OF SNOW WORKING INTO NORTHEAST SOUTH DAKOTA AND PERSISTING THERE INTO THE EARLY EVENING HOURS. WITH WORD COMING THIS MORNING FROM MY WESTERN FORECAST NEIGHBOR THAT THEY HAD ALREADY RECEIVED REPORTS OF 5 TO 8 INCHES OF SNOWFALL IN THEIR AREA IN A SPAN OF LESS THEN 6 HOURS...THINKING THAT OUR WINTER WEATHER ADVISORY FOR A MIXTURE OF PRECIPITATION TYPES AND 2 TO 5 INCHES OF SNOWFALL MAY NOT BE ENOUGH TO COVER THE SNOW TOTALS ACROSS NORTH CENTRAL SOUTH DAKOTA THAT ARE CURRENTLY PILING UP. ONCE THIS LOW DEPARTS SOUTH DAKOTA THIS EVENING...HIGH PRESSURE AT THE SURFACE AND ALOFT WORKS INTO THE FORECAST AREA...CLEARING AND DRYING THINGS OUT THROUGH PRETTY MUCH THE REMAINDER OF THE SHORT TERM FORECAST. THE 00Z GFS AND ECMWF MODELS CONTINUE TO TREND THE BROAD UPPER LEVEL TROF OF LOW PRESSURE FURTHER SOUTH AND EAST MONDAY NIGHT THROUGH TUESDAY NIGHT. SO...CONTINUED TO SHAVE MORE OFF OF THE POPS/WX FORECAST FOR SAID TIME FRAME. MODEL THERMAL PROGS STILL LEAVE MUCH TO BE DESIRED FOR NAILING DOWN THE PRECIPITATION TYPE WITH THIS RATHER WEAK/ILL-DEFINED SYSTEM...SO CONTINUED A FORECAST OF RAIN OR SNOW CHANCES ACROSS MAINLY THE SOUTHERN HALF OF THE FORECAST AREA. NO SIGNIFICANT CHANGES TO THE GOING MAX/MIN T FORECAST IN THE SHORT TERM. WILL HAVE TO SEE WHAT SHAKES OUT OF THE ONGOING SNOW EVENT IN ORDER TO BETTER DEFINE MAX/MIN T FORECAST FOR MONDAY AND TUESDAY. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY BIGGEST CHALLENGE IN THE EXTENDED STILL DEALS WITH PCPN CHANCES MID WEEK AND TOWARD THE END OF THE WEEK. MODELS ARE NOW TAKING THE MID WEEK SYSTEM A BIT FURTHER SOUTH...WITH SFC HIGH PRESSURE NOW BUILDING SOUTH INTO THE EASTERN DAKOTAS 00Z WED THROUGH 12Z WED. THETA SURFACES INDICATE DOWNGLIDE TAKING PLACE...SO SAW NO REASON TO LEAVE IN MENTION OF PCPN. ENSEMBLE GUIDANCE HAS ALSO FALLEN TO LESS THAN SLIGHT CHC POPS. ATTENTION THEN TURNS TOWARD THURSDAY AFTERNOON/FRIDAY SYSTEM. BOTH GFS AND EC ARE NOW LIFTING THE SFC LOW NORTHWARD INTO THE PLAINS BY 12Z FRIDAY. THE LATEST 00Z EC IS NOW PUSHING THE SFC LOW A BIT FURTHER TO THE EAST COMPARED TO THE PREVIOUS 12Z RUN...BUT IT STILL APPEARS THAT PCPN AT LEAST DESERVES A CHC MENTION THURSDAY NIGHT INTO FRIDAY. 00Z GFS SHOWS WELL DEFINED 7H TROWAL ACROSS NERN SD BY 12Z FRIDAY...WITH 290K SPEC HUMIDITIES NEARING 3G/KG BY 12Z FRIDAY. WITH MODELS STILL TRYING TO NAIL DOWN EXACT PLACEMENT OF THE OVERALL FEATURES...AM COMFORTABLE WITH LOW CHC POPS UNTIL THINGS BECOME A BIT MORE CERTAIN. WITH HIGH PRESSURE NOW NOSING DOWN INTO CWA FOR WEDNESDAY PERIOD...HAVE NUDGED UP WEDNESDAY FCST HIGHS A DEGREE OR THREE...ESPECIALLY ACROSS THE NE WHERE AMPLE SUNSHINE WILL SUPPORT INCREASED HIGHS. REMAINDER OF TEMP GRIDS PRETTY MUCH LEFT WHAT WAS INHERITED. && .AVIATION... CIGS ACROSS THE CWA WILL BE MAINLY IN THE LIFR TO IFR CATEGORIES BETWEEN 100 AND 800 FEET THROUGH THE AFTERNOON. THE EXCEPTION WILL BE OVER THE SOUTHWESTERN CWA NEAR KPIR...WHERE HIGH IFR TO MVFR CIGS ARE EXPECTED BETWEEN 800 AND 1800 FEET. SNOW WILL CONTINUE ACROSS THE NORTHWESTERN AND CENTRAL PARTS OF THE CWA...REDUCING VSBYS INTO THE LIFR/IFR CATEGORIES BETWEEN 1/4 MILE AND 2 MILES...MAINLY AFFECTING KMBG AND KABR. THE AREA OF SNOW WILL SLIDE EAST LATER THIS AFTERNOON AND THIS EVENING...AFFECTING KATY AROUND OR SHORTLY AFTER 20Z. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER STORM WARNING UNTIL 1 PM CDT /NOON MDT/ THIS AFTERNOON FOR CAMPBELL-CORSON-DEWEY-POTTER-WALWORTH. WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR CODINGTON- GRANT-HAMLIN-ROBERTS. WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR BROWN-CLARK- DAY-EDMUNDS-FAULK-MARSHALL-MCPHERSON-SPINK. WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR HAND- HYDE-SULLY. MN...WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR BIG STONE- TRAVERSE. && $$ UPDATE...PARKIN SHORT TERM...DORN LONG TERM...HINTZ AVIATION...PARKIN WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 934 AM CDT SUN APR 6 2008 .UPDATE... UPDATED FORECAST EARLIER TO ACCOUNT FOR LIKELIHOOD OF HIGHER SNOW AMOUNTS THAN PREVIOUSLY FORECASTED. EXPECT NORTH CENTRAL AND NORTHEASTERN SOUTH DAKOTA TO SEE UPWARDS OF 5 TO 8 INCHES OF SNOW TODAY. UPGRADED THE WINTER WEATHER ADVISORY TO A WINTER STORM WARNING. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH TUESDAY FORECAST CHALLENGES IS SNOWFALL AMOUNTS AND TIMING THE CHANGE OF PRECIPITATION TYPE AS THE DAY WEARS ON. CURRENTLY...A VIGOROUS EARLY SPRING WINTER STORM SYSTEM IS WORKING ITS WAY ACROSS SOUTH DAKOTA. THE TROWAL/DEFORMATION ZONE ON THIS LOW IS QUITE EVIDENT IN SATELLITE/RADAR IMAGERY ACROSS WESTERN SOUTH DAKOTA AND EXTREME SOUTH CENTRAL NORTH DAKOTA...AND IS SPREADING SNOW EASTWARD ACROSS THIS FORECAST AREA /IN PARTICULAR...NORTH CENTRAL SOUTH DAKOTA/. LIGHTNING HAS BEEN DETECTED IN ASSOCIATION WITH SNOW FALLING THIS MORNING OVER CENTRAL SOUTH DAKOTA...AND AN IMPRESSIVE BAND OF 30 TO 40 DBZ ECHOES HAS DEVELOPED ACROSS NORTH CENTRAL SOUTH DAKOTA WITH A FEW REPORTS FROM LAW ENFORCEMENT EARLY THIS MORNING INDICATING SLICK ROADS AND LIGHT SNOW ACCUMULATIONS...THUS FAR...FROM A COMBINATION OF SNOW AND SLEET. TO COMPLICATE THINGS FURTHER...SURFACE TO 925HPA CAA IS UNDERCUTTING THE STRONG SURGE OF WARM/MOIST AIR FROM THE SOUTH THIS MORNING...CREATING /BASED OFF REAL-TIME RUC- CASTING/ AN AREA SUPPORTIVE OF FREEZING RAIN AND SLEET. SURFACE TO 925HPA TEMPERATURES ARE COOLING FROM NORTH TO SOUTH AND FALLING BELOW THE FREEZING MARK ACROSS PRETTY MUCH EVERYWHERE BUT THE FAR EASTERN ZONES THIS MORNING. MEANWHILE 850HPA TEMPS ARE STILL ANYWHERE FROM 1 TO 5 DEGREES C ABOVE FREEZING ON TOP OF THIS COLDER LAYER LOWER DOWN. THIS POTENTIAL CORRIDOR OF FREEZING RAIN AND SLEET...MIXING WITH AND CHANGING OVER TO SNOW WILL PRECEDE THE HEAVY WET TROWAL-FORCED SNOW BAND CHASING IT FROM WEST TO EAST ACROSS THE FORECAST AREA TODAY. BY NOON CDT...THE THREAT FOR FREEZING PRECIPITATION IS PRETTY MUCH RELEGATED TO MINNESOTA...WITH JUST A HEAVY WET BAND OF SNOW WORKING INTO NORTHEAST SOUTH DAKOTA AND PERSISTING THERE INTO THE EARLY EVENING HOURS. WITH WORD COMING THIS MORNING FROM MY WESTERN FORECAST NEIGHBOR THAT THEY HAD ALREADY RECEIVED REPORTS OF 5 TO 8 INCHES OF SNOWFALL IN THEIR AREA IN A SPAN OF LESS THEN 6 HOURS...THINKING THAT OUR WINTER WEATHER ADVISORY FOR A MIXTURE OF PRECIPITATION TYPES AND 2 TO 5 INCHES OF SNOWFALL MAY NOT BE ENOUGH TO COVER THE SNOW TOTALS ACROSS NORTH CENTRAL SOUTH DAKOTA THAT ARE CURRENTLY PILING UP. ONCE THIS LOW DEPARTS SOUTH DAKOTA THIS EVENING...HIGH PRESSURE AT THE SURFACE AND ALOFT WORKS INTO THE FORECAST AREA...CLEARING AND DRYING THINGS OUT THROUGH PRETTY MUCH THE REMAINDER OF THE SHORT TERM FORECAST. THE 00Z GFS AND ECMWF MODELS CONTINUE TO TREND THE BROAD UPPER LEVEL TROF OF LOW PRESSURE FURTHER SOUTH AND EAST MONDAY NIGHT THROUGH TUESDAY NIGHT. SO...CONTINUED TO SHAVE MORE OFF OF THE POPS/WX FORECAST FOR SAID TIME FRAME. MODEL THERMAL PROGS STILL LEAVE MUCH TO BE DESIRED FOR NAILING DOWN THE PRECIPITATION TYPE WITH THIS RATHER WEAK/ILL-DEFINED SYSTEM...SO CONTINUED A FORECAST OF RAIN OR SNOW CHANCES ACROSS MAINLY THE SOUTHERN HALF OF THE FORECAST AREA. NO SIGNIFICANT CHANGES TO THE GOING MAX/MIN T FORECAST IN THE SHORT TERM. WILL HAVE TO SEE WHAT SHAKES OUT OF THE ONGOING SNOW EVENT IN ORDER TO BETTER DEFINE MAX/MIN T FORECAST FOR MONDAY AND TUESDAY. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY BIGGEST CHALLENGE IN THE EXTENDED STILL DEALS WITH PCPN CHANCES MID WEEK AND TOWARD THE END OF THE WEEK. MODELS ARE NOW TAKING THE MID WEEK SYSTEM A BIT FURTHER SOUTH...WITH SFC HIGH PRESSURE NOW BUILDING SOUTH INTO THE EASTERN DAKOTAS 00Z WED THROUGH 12Z WED. THETA SURFACES INDICATE DOWNGLIDE TAKING PLACE...SO SAW NO REASON TO LEAVE IN MENTION OF PCPN. ENSEMBLE GUIDANCE HAS ALSO FALLEN TO LESS THAN SLIGHT CHC POPS. ATTENTION THEN TURNS TOWARD THURSDAY AFTERNOON/FRIDAY SYSTEM. BOTH GFS AND EC ARE NOW LIFTING THE SFC LOW NORTHWARD INTO THE PLAINS BY 12Z FRIDAY. THE LATEST 00Z EC IS NOW PUSHING THE SFC LOW A BIT FURTHER TO THE EAST COMPARED TO THE PREVIOUS 12Z RUN...BUT IT STILL APPEARS THAT PCPN AT LEAST DESERVES A CHC MENTION THURSDAY NIGHT INTO FRIDAY. 00Z GFS SHOWS WELL DEFINED 7H TROWAL ACROSS NERN SD BY 12Z FRIDAY...WITH 290K SPEC HUMIDITIES NEARING 3G/KG BY 12Z FRIDAY. WITH MODELS STILL TRYING TO NAIL DOWN EXACT PLACEMENT OF THE OVERALL FEATURES...AM COMFORTABLE WITH LOW CHC POPS UNTIL THINGS BECOME A BIT MORE CERTAIN. WITH HIGH PRESSURE NOW NOSING DOWN INTO CWA FOR WEDNESDAY PERIOD...HAVE NUDGED UP WEDNESDAY FCST HIGHS A DEGREE OR THREE...ESPECIALLY ACROSS THE NE WHERE AMPLE SUNSHINE WILL SUPPORT INCREASED HIGHS. REMAINDER OF TEMP GRIDS PRETTY MUCH LEFT WHAT WAS INHERITED. && .AVIATION... MVFR/IFR CONDS ARE EXPECTED THROUGH 00Z FOR KABR/KATY/KPIR TERMINALS. SFC LOW NOW SLIDING EAST ALONG HWY 14 CORRIDOR WILL BRING AMPLE SHRA/SN TO THE AREA. FURTHER EAST ALONG I-29...SCT SHRA WITH ISOLD -TSRA ARE POSSIBLE THROUGH 15Z. BY 15Z PCPN WILL HAVE TURNED OVER TO SNOW FOR KMBG...WITH SNOW EXPECTED BY 18Z FOR KABR. VSBYS COULD FALL TO LESS THAN 1SM IN THE SNOW. CIGS ARE EXPECTED TO VARY FROM 008-012 FEET AGL THROUGH 00Z MONDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER STORM WARNING UNTIL 1 PM CDT /NOON MDT/ THIS AFTERNOON FOR CAMPBELL-CORSON-DEWEY-POTTER-WALWORTH. WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR CODINGTON- GRANT-HAMLIN-ROBERTS. WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR BROWN-CLARK- DAY-EDMUNDS-FAULK-MARSHALL-MCPHERSON-SPINK. WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR HAND- HYDE-SULLY. MN...WINTER STORM WARNING UNTIL 10 PM CDT THIS EVENING FOR BIG STONE- TRAVERSE. && $$ UPDATE...PARKIN SHORT TERM...DORN LONG TERM...HINTZ AVIATION...HINTZ WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...DELAYED NATIONAL WEATHER SERVICE ABERDEEN SD 505 AM CDT SUN APR 6 2008 .SHORT TERM...TODAY THROUGH TUESDAY FORECAST CHALLENGES IS SNOWFALL AMOUNTS AND TIMING THE CHANGE OF PRECIPITATION TYPE AS THE DAY WEARS ON. CURRENTLY...A VIGOROUS EARLY SPRING WINTER STORM SYSTEM IS WORKING ITS WAY ACROSS SOUTH DAKOTA. THE TROWAL/DEFORMATION ZONE ON THIS LOW IS QUITE EVIDENT IN SATELLITE/RADAR IMAGERY ACROSS WESTERN SOUTH DAKOTA AND EXTREME SOUTH CENTRAL NORTH DAKOTA...AND IS SPREADING SNOW EASTWARD ACROSS THIS FORECAST AREA /IN PARTICULAR...NORTH CENTRAL SOUTH DAKOTA/. LIGHTNING HAS BEEN DETECTED IN ASSOCIATION WITH SNOW FALLING THIS MORNING OVER CENTRAL SOUTH DAKOTA...AND AN IMPRESSIVE BAND OF 30 TO 40 DBZ ECHOES HAS DEVELOPED ACROSS NORTH CENTRAL SOUTH DAKOTA WITH A FEW REPORTS FROM LAW ENFORCEMENT EARLY THIS MORNING INDICATING SLICK ROADS AND LIGHT SNOW ACCUMULATIONS...THUS FAR...FROM A COMBINATION OF SNOW AND SLEET. TO COMPLICATE THINGS FURTHER...SURFACE TO 925HPA CAA IS UNDERCUTTING THE STRONG SURGE OF WARM/MOIST AIR FROM THE SOUTH THIS MORNING...CREATING /BASED OFF REAL-TIME RUC- CASTING/ AN AREA SUPPORTIVE OF FREEZING RAIN AND SLEET. SURFACE TO 925HPA TEMPERATURES ARE COOLING FROM NORTH TO SOUTH AND FALLING BELOW THE FREEZING MARK ACROSS PRETTY MUCH EVERYWHERE BUT THE FAR EASTERN ZONES THIS MORNING. MEANWHILE 850HPA TEMPS ARE STILL ANYWHERE FROM 1 TO 5 DEGREES C ABOVE FREEZING ON TOP OF THIS COLDER LAYER LOWER DOWN. THIS POTENTIAL CORRIDOR OF FREEZING RAIN AND SLEET...MIXING WITH AND CHANGING OVER TO SNOW WILL PRECEDE THE HEAVY WET TROWAL-FORCED SNOW BAND CHASING IT FROM WEST TO EAST ACROSS THE FORECAST AREA TODAY. BY NOON CDT...THE THREAT FOR FREEZING PRECIPITATION IS PRETTY MUCH RELEGATED TO MINNESOTA...WITH JUST A HEAVY WET BAND OF SNOW WORKING INTO NORTHEAST SOUTH DAKOTA AND PERSISTING THERE INTO THE EARLY EVENING HOURS. WITH WORD COMING THIS MORNING FROM MY WESTERN FORECAST NEIGHBOR THAT THEY HAD ALREADY RECEIVED REPORTS OF 5 TO 8 INCHES OF SNOWFALL IN THEIR AREA IN A SPAN OF LESS THEN 6 HOURS...THINKING THAT OUR WINTER WEATHER ADVISORY FOR A MIXTURE OF PRECIPITATION TYPES AND 2 TO 5 INCHES OF SNOWFALL MAY NOT BE ENOUGH TO COVER THE SNOW TOTALS ACROSS NORTH CENTRAL SOUTH DAKOTA THAT ARE CURRENTLY PILING UP. ONCE THIS LOW DEPARTS SOUTH DAKOTA THIS EVENING...HIGH PRESSURE AT THE SURFACE AND ALOFT WORKS INTO THE FORECAST AREA...CLEARING AND DRYING THINGS OUT THROUGH PRETTY MUCH THE REMAINDER OF THE SHORT TERM FORECAST. THE 00Z GFS AND ECMWF MODELS CONTINUE TO TREND THE BROAD UPPER LEVEL TROF OF LOW PRESSURE FURTHER SOUTH AND EAST MONDAY NIGHT THROUGH TUESDAY NIGHT. SO...CONTINUED TO SHAVE MORE OFF OF THE POPS/WX FORECAST FOR SAID TIME FRAME. MODEL THERMAL PROGS STILL LEAVE MUCH TO BE DESIRED FOR NAILING DOWN THE PRECIPITATION TYPE WITH THIS RATHER WEAK/ILL-DEFINED SYSTEM...SO CONTINUED A FORECAST OF RAIN OR SNOW CHANCES ACROSS MAINLY THE SOUTHERN HALF OF THE FORECAST AREA. NO SIGNIFICANT CHANGES TO THE GOING MAX/MIN T FORECAST IN THE SHORT TERM. WILL HAVE TO SEE WHAT SHAKES OUT OF THE ONGOING SNOW EVENT IN ORDER TO BETTER DEFINE MAX/MIN T FORECAST FOR MONDAY AND TUESDAY. .LONG TERM...00Z WED THROUGH SATURDAY. BIGGEST CHALLENGE IN THE EXTENDED STILL DEALS WITH PCPN CHANCES MID WEEK AND TOWARD THE END OF THE WEEK. MODELS ARE NOW TAKING THE MID WEEK SYSTEM A BIT FURTHER SOUTH...WITH SFC HIGH PRESSURE NOW BUILDING SOUTH INTO THE EASTERN DAKOTAS 00Z WED THROUGH 12Z WED. THETA SURFACES INDICATE DOWNGLIDE TAKING PLACE...SO SAW NO REASON TO LEAVE IN MENTION OF PCPN. ENSEMBLE GUIDANCE HAS ALSO FALLEN TO LESS THAN SLIGHT CHC POPS. ATTENTION THEN TURNS TOWARD THURSDAY AFTERNOON/FRIDAY SYSTEM. BOTH GFS AND EC ARE NOW LIFTING THE SFC LOW NORTHWARD INTO THE PLAINS BY 12Z FRIDAY. THE LATEST 00Z EC IS NOW PUSHING THE SFC LOW A BIT FURTHER TO THE EAST COMPARED TO THE PREVIOUS 12Z RUN...BUT IT STILL APPEARS THAT PCPN AT LEAST DESERVES A CHC MENTION THURSDAY NIGHT INTO FRIDAY. 00Z GFS SHOWS WELL DEFINED 7H TROWAL ACROSS NERN SD BY 12Z FRIDAY...WITH 290K SPEC HUMIDITIES NEARING 3G/KG BY 12Z FRIDAY. WITH MODELS STILL TRYING TO NAIL DOWN EXACT PLACEMENT OF THE OVERALL FEATURES...AM COMFORTABLE WITH LOW CHC POPS UNTIL THINGS BECOME A BIT MORE CERTAIN. WITH HIGH PRESSURE NOW NOSING DOWN INTO CWA FOR WEDNESDAY PERIOD...HAVE NUDGED UP WEDNESDAY FCST HIGHS A DEGREE OR THREE...ESPECIALLY ACROSS THE NE WHERE AMPLE SUNSHINE WILL SUPPORT INCREASED HIGHS. REMAINDER OF TEMP GRIDS PRETTY MUCH LEFT WHAT WAS INHERITED. && .AVIATION... MVFR/IFR CONDS ARE EXPECTED THROUGH 00Z FOR KABR/KATY/KPIR TERMINALS. SFC LOW NOW SLIDING EAST ALONG HWY 14 CORRIDOR WILL BRING AMPLE SHRA/SN TO THE AREA. FURTHER EAST ALONG I-29...SCT SHRA WITH ISOLD -TSRA ARE POSSIBLE THROUGH 15Z. BY 15Z PCPN WILL HAVE TURNED OVER TO SNOW FOR KMBG...WITH SNOW EXPECTED BY 18Z FOR KABR. VSBYS COULD FALL TO LESS THAN 1SM IN THE SNOW. CIGS ARE EXPECTED TO VARY FROM 008-012 FEET AGL THROUGH 00Z MONDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL NOON CDT /11 AM MDT/ TODAY FOR CAMPBELL-CORSON-DEWEY-POTTER-WALWORTH. WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 10 PM CDT THIS EVENING FOR CODINGTON-GRANT-HAMLIN-ROBERTS. WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR BROWN- CLARK-DAY-EDMUNDS-FAULK-HAND-HYDE-MARSHALL-MCPHERSON-SPINK- SULLY. MN...WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 10 PM CDT THIS EVENING FOR BIG STONE-TRAVERSE. && $$ SHORT TERM...DORN LONG TERM...HINTZ AVIATION...HINTZ WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1130 AM CDT MON APR 7 2008 .AVIATION UPDATE... STRATUS HAS DISSIPATED. WE EXPECT SCATTERED CUMULUS TO FORM IN THE AFTERNOON. A THUNDERSTORM OR TWO CROSS OVER THE OKLAHOMA BORDER LATE THIS AFTERNOON OR EVENING...BUT THE BULK OF THE STRONG STORMS LIKELY WILL STILL NORTH OF THE RIVER. STRATUS WILL FORM AGAIN TONIGHT... PROBABLY IN MORE WIDESPREAD FASHION THAN THIS MORNING. #26 .UPDATE... 1045 AM CDT SUNDAY EVENING POSTFRONTAL WINDS OVER THE BIG COUNTRY BACKED RAPIDLY OVERNIGHT...SETTING UP THE MORNING DRYLINE NEAR THE NEW MEXICO BORDER. WITH SW/SSW WINDS ABOVE THE BOUNDARY LAYER...THERE WILL BE LITTLE MECHANICAL FORCING TO THE EAST. SOME MIXING PROPAGATION WILL OCCUR IN THE SUNNY AREAS TO THE WEST OF FWD CWA...BUT DRYLINE BULGE WILL LIKELY BE INTO SW OKLAHOMA. AS EXPECTED...NEW 12Z MODELS HAVE DIMINISHED THE EASTWARD PROGRESSION OF THE DRYLINE. RUC/NAM STILL GENERATING MUCAPES (1000-900MB) IN EXCESS OF 3000J/KG TO THE EAST OF THE BOUNDARY. WITH NEGLIGIBLE CONVERGENCE...BOUNDARY MOVEMENT ALONE MAY BE INSUFFICIENT TO REALIZE THIS EXTRAORDINARY INSTABILITY. ANY NEAR-BOUNDARY CONVECTIVE INITIATION THIS AFTERNOON WOULD BE WEST OF FWD CWA...WITH STORM MOTION TO THE NE. AS A RESULT...FAR NW ZONES MAY GET GRAZED...WITH NO OTHER IMPACTS THIS AFTERNOON. WILL MAINTAIN POP GRIDS AS IS...WITH SEVERE MENTION IN FAR NW...BUT ONLY 10 POPS THROUGHOUT THE REMAINDER OF RECENTLY EXPANDED SPC SLIGHT RISK AREA. OTHERWISE...ONLY MINOR ADJUSTMENTS TO HOURLY DATA TO ACCOUNT FOR CURRENT TRENDS. UPDATED IMAGES/PRODUCTS TO BE ISSUED SHORTLY. 25 && .AVIATION... 715 AM CDT /12Z TAFS/ MOISTURE HAS BEEN SLOW TO GET TO DFW AREA TAFS...SO VFR CONDITIONS HELD THROUGH THE NIGHT. HOWEVER...DO NOT WANT TO COMPLETELY PULL BR OUT OF TAFS BECAUSE IT IS CURRENTLY PATCHY ALL AROUND THE DFW TAF SITES. SO...LEFT BR IN BUT BACKED IT UP FROM 12Z TO 13Z. EXPECT IT TO SCATTER OUT RATHER QUICKLY BETWEEN 15Z/16Z AND RETURN TO VFR CONDITIONS. FURTHER SOUTH...IFR CONDITIONS HAVE BEEN STEADY SINCE 09Z AT ACT... DO NOT EXPECT MVFR CONDITIONS UNTIL AROUND 16Z. WINDS WILL INCREASE BY EARLY AFTERNOON AND CONTINUE THROUGH TOMORROW NIGHT. SKIES WILL BECOME OVC TOMORROW NIGHT AND REMAIN MVFR. VCTS WILL MOST LIKELY NEED TO BE ADDED LATE IN THE TAF PERIOD...BUT CONFIDENCE IS TOO LOW AT THIS TIME TO INCORPORATE INTO TAFS. 77/TDUD && .PREV DISCUSSION... 403 AM CDT THE 11-3.9 MICRON SATELLITE LOOPS SHOWS A LARGE AREA OF STRATUS FROM SOUTH CENTRAL AND SOUTHEAST TEXAS NORTH INTO THE EXTREME SOUTHERN PARTS OF NORTH TEXAS AS OF 08Z. THESE LOW CLOUDS WILL SPREAD NORTHWARD ACROSS MUCH OF NORTH TEXAS THIS MORNING ON A 35 KNOT LOW LEVEL JET. A WEAK COLD FRONT HAS SUNK SOUTH OF I-20...AND EXTENDED ALONG A BROWNWOOD...TO HILLSBORO...ATHENS LINE AS OF 08Z. THIS FRONT WILL LIFT BACK NORTH LATER TODAY AND A DRY LINE IS EXPECTED TO DEVELOP ACROSS WEST TEXAS. WE WILL BE CAPPED ACROSS NORTH TEXAS TODAY...HOWEVER...THUNDERSTORMS MAY FORM ACROSS SOUTHWEST OKLAHOMA INTO NORTHWEST TEXAS AHEAD OF THE DRYLINE. GIVEN THE FORECAST CAPES...AND STEEP LAPSE RATES...THERE WILL BE THE POTENTIAL FOR SOME SEVERE THUNDERSTORMS ACROSS THE NORTHWESTERN ZONES LATE THIS AFTERNOON AND ACROSS THE NORTH TONIGHT. THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS AREAWIDE TUESDAY AS A PACIFIC COLD FRONT ACROSS THE STATE. RAIN CHANCES WILL CONTINUE THROUGH THURSDAY WHEN A SHORTWAVE WILL MOVE ACROSS THE SOUTHERN PLAINS AND PUSH A STRONGER FRONT THROUGH NORTH TEXAS. DRY WEATHER IS THEN EXPECTED FRIDAY THROUGH THE WEEKEND. #58 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 81 65 78 54 67 / 10 20 40 50 50 WACO, TX 82 67 80 60 74 / 5 10 30 50 40 PARIS, TX 78 61 76 55 69 / 10 20 60 50 50 DENTON, TX 80 64 78 54 64 / 10 20 40 50 50 MCKINNEY, TX 78 63 77 56 68 / 10 20 40 50 50 DALLAS, TX 80 66 79 56 69 / 10 20 40 50 50 TERRELL, TX 82 65 78 58 72 / 5 20 40 50 50 CORSICANA, TX 81 64 81 61 75 / 5 10 40 50 40 TEMPLE, TX 82 65 81 62 79 / 5 10 30 40 40 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 26/25/84 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 1200 PM CDT MON APR 7 2008 .FIRE WEATHER... LITTLE CHANGE IN THINKING FROM EARLIER SHIFT. STILL EXPECT DEEPENING AREA OF LOW PRESSURE OVER NORTHEAST NEW MEXICO TO BRING STRENGTHENING SOUTHWEST WINDS TO THE CAPROCK AND SOUTHERN ROLLING PLAINS THIS AFTERNOON. THIS WILL RESULT IN WARM AND DRY AIR PRODUCING RH VALUES DROPPING TO 10 PERCENT OR SLIGHTLY BELOW FOR MUCH OF THE AREA. HOWEVER...THE RUC AND TO A LESSER DEGREE THE GFS KEEP A SOUTHERLY COMPONENT TO THE WINDS AND SLIGHTLY IMPROVED MOISTURE LEVELS OVER OUR VERY EASTERN ZONES...WHICH WOULD HELP TO MITIGATE FIRE WEATHER THREAT THERE IF REALIZED. THIS WILL BE MONITORED AND VERY SOUTHEAST EXTENT OF RED FLAG WARNING MAY NEED TO BE TRIMMED IF THIS LOOKS TO BE THE REALITY. OF NOTE...THE RUC DOES APPEAR TO BE RUNNING A BIT HIGH ON CURRENT MOISTURE FORECASTS...SO A LEAN TOWARD THE DRY SOLUTIONS MAY BE MORE REALISTIC. OTHERWISE...THE MAGNITUDE OF THE WIND SPEED THIS AFTERNOON CONTINUES TO BE THE OTHER WILD CARD WITH REGARDS TO CURRENT FIRE WEATHER HIGHLIGHTS. MODELS ARE IN GOOD AGREEMENT THAT THE SURFACE LOW CURRENTLY IN NE NM WILL TRACK EAST AND SE THROUGH THE AFTERNOON...AND BE LOCATED OVER THE WESTERN TEXAS PANHANDLE BY 00Z. THIS WILL KEEP THE SURFACE PRESSURE GRADIENT RATHER WEAK ACROSS THE NORTHWEST ZONES...AND MAY KEEP WINDS BELOW ABSOLUTE RED FLAG CRITERIA /SUSTAINED 20FT WINDS AT 20 MPH FOR 3 HRS/. STILL...EVEN IF WINDS DO FALL A BIT SHORT OF THE CRITERIA...VERY DRY CONDITIONS AND AT LEAST BREEZY CONDITIONS WILL KEEP THE FIRE DANGER VERY HIGH HERE. MODELS ARE IN BETTER AGREEMENT THAT THE SOUTHERN HALF OF THE SOUTH PLAINS INTO THE SOUTHERN ROLLING PLAINS WILL SEE WINDS SOMEWHERE AROUND THE 20 MPH CRITERIA THIS AFTERNOON AS A LLJ SPREADS ACROSS FROM SE NM AND FAR WEST TEXAS. ALL SAID...WILL CONTINUE WITH RED FLAG WARNING AS IS FOR NOW...BUT MAY NEED TO TRIM AS THE DAY UNFOLDS...WITH THE SOUTHWEST TEXAS PANHANDLE AND SOUTHEAST ROLLING PLAINS IN MOST DOUBT FOR ABOVE MENTIONED REASONS. && .PREV DISCUSSION... /ISSUED 353 AM CDT MON APR 7 2008/ SHORT TERM... A STATIONARY FRONTAL BOUNDARY LOCATED FROM A SFC LOW JUST EAST OF LAS VEGAS NEW MEXICO SOUTHEAST TO NR ODESSA WILL BEGIN LIFTING NORTHWARD TODAY...AS A SFC LEE SIDE TROUGH DEEPENS OVER THE ERN PLAINS OF NEW MEXICO. TO THE WEST AND SOUTH OF THIS BOUNDARY...THE ATMOSPHERE WILL BE VERY DRY AND WARM TODAY. THIS BOUNDARY WILL PUSH NORTH AND EAST THROUGH MUCH OF THE CWFA BY MID AFTERNOON. THE RESULT WILL BE A RETURN TO BREEZY AND WARM SOUTHWEST WINDS WHICH WILL HELP TO BOOST TEMPS BACK UP INTO THE 80S FOR MOST LOCATIONS. UNFORTUNATELY...THIS SCENARIO WILL ONCE AGAIN RESULT IN FIRE WEATHER CONCERNS WHICH ARE ADDRESSED BELOW. FOR TONIGHT...THE SURFACE LOW WILL MOVE EAST ACRS THE TX PANHANDLE AS A H50 SHORTWAVE BEGINS TO TRANSLATE THRU THE SRN PLAINS. AS THIS OCCURS...A COLD FRONT WILL DIVE SOUTH THRU THE PANHANDLES AND INTO THE NORTHERN CWFA BY 12Z WITH WINDS SHIFTING TO THE NORTH. SOME LOW CLOUDS MAY ACCOMPANY THE FRONTAL PASSAGE LATE TONIGHT. LONG TERM... THE COLD FRONT SHOULD CLEAR THE FA BY LATE MORNING WITH BRISK NORTHERLY WINDS SLOWLY TAPERING OFF AND COMING AROUND TO THE EAST BY EVENING. TEMPS SHOULD COOL OFF SOME...WITH HIGH TEMPS IN THE 70S EXPECTED. LATE TUESDAY NIGHT A 30-40 KT LLJ FROM THE SE DEVELOPS AND ISENTROPIC UPGLIDE INCREASES ACROSS THE AREA. THIS SHOULD LEAD TO THE DEVELOPMENT OF LOW STRATUS ACROSS MUCH OF THE AREA BY WED MORN. MEANWHILE...THE WELL ADVERTISED UPPER LOW/TROUGH WILL BE MOVING ACROSS THE GREAT BASIN. 0Z GUIDANCE IS NOW IN DECENT AGREEMENT WITH THE PATH OF THIS SYSTEM...AND CONFIDENCE HAS INCREASED THAT WE WILL SEE SOME SHOWER/TSTM ACTIVITY WED AND WED NIGHT...ESPECIALLY ACROSS THE EASTERN SPLNS AND ROLLING PLAINS. LARGE SCALE ASCENT SHOULD BEGIN TO SPREAD ACROSS THE AREA DURING THE DAY AS LEAD SHTWV LIFTS NE OUT OF THE SRN ROCKIES. LIFT FROM THIS WAVE WILL BE MAXIMIZED NORTH...WHILE THE WARM FRONT SHOULD STILL BE DOWN IN THE PERMIAN BASIN. THUS FEEL THAT WE COULD SEE A FEW SHOWERS ACROSS OUR NW ZONES ON THE NOSE OF THE LLJ WHILE THE THREAT OF SFC-BASED CONVECTION WILL INITIALLY BE TO OUR SOUTH. SFC CYCLOGENESIS IS EXPECTED TO OCCUR AS FAR SOUTH AS SE NM DURING THE DAY WHICH SHOULD MAINTAIN LOW-LVL MOISTURE TRANSPORT INTO MOST OF THE FA...EXPECT POSSIBLY THE SW COUNTIES. BY LATE AFTN INTO EVENING...LIFT FROM THE MAIN TROUGH AND A STRENGTHENING /AND VEERING/ SRLY LLJ SHOULD ALLOW TSTM ACTIVITY TO BLOSSOM ACROSS THE ROLLING PLAINS AND HAVE UPPED POPS TO ABOUT 50 PERCENT THAT AREA. THE HIGH DEGREE OF DEEP SHEAR AND ELEVATED CAPE WILL LEAD TO A SVR THREAT MAINLY ACROSS OUR SE ZONES WITH LARGE HAIL APPEARING TO BE THE MAIN THREAT. STILL SOME UNCERTAINLY HOW QUICKLY THE ACTIVITY WILL SHIFT EASTWARD OVERNIGHT...WITH MOST GUIDANCE INDICATING THAT PRECIP CHANCES WILL END FOR OUR EASTERN ZONES BY 12Z THU. THE FCST LOOKS COMPLICATED FOR THU AS WELL. THE MAIN UPPER LOW MOVES NE AND DEEPENS ACROSS THE CENTRAL PLAINS/MISSOURI VALLEY. STRONG WESTERLY WINDS MAY DEVELOP ACROSS OUR WESTERN AND SOUTHERN ZONES WHILE A TRAILING MID-LVL SHTWV MOVES ACROSS THE PANHANDLE...SKIRTING OUR NRN ZONES. WHILE LOW-LVL MOISTURE WILL BE LACKING...COLD MID-LVL TEMPS MAY BE SUFFICIENT FOR SOME SHOWER DEVELOPMENT DURING THE AFTN IN THIS AREA. THE WIND SHOULD BECOME NW-N FRIDAY AS COLD FRONT WORKS THROUGH THE AREA. THE GFS AND ECMWF DIFFER ON THE DETAILS FOR THE WEEKEND BUT NW FLOW ALOFT SHOULD MAINTAIN COOLER TEMPS FRI/SAT WITH A WARMING TREND IN STORE SUN/MON. FIRE WEATHER... BREEZY SOUTHWEST WINDS WILL RETURN TO THE SOUTH PLAINS AND ROLLING PLAINS TODAY AS A SURFACE TROUGH OF LOW PRESSURE DEEPENS ACROSS EASTERN NEW MEXICO. THE DOWNSLOPE WINDS WILL BRING ABOVE NORMAL TEMPERATURES AND VERY DRY AIR SPREADING BACK ACROSS MUCH OF THE AREA THIS AFTERNOON. AS TEMPS CLIMB INTO THE 80S...RH VALUES WILL LIKELY DROP TO BTWN 10 AND 15 PERCENT OVER THE CAPROCK AND SOUTHERN ROLLING PLAINS. THIS...COMBINED WITH WIND SPEEDS SUSTAINED AROUND 20 MPH AT 20 FT AND DRY FUELS...WILL CREATE AREAS OF CRITICAL FIRE WEATHER THIS AFTERNOON AND EVENING. THERE DOES REMAIN SOME QUESTION WHETHER WIND SPEEDS WILL REMAIN SUSTAINED AT 20 MPH FOR A 3 HR DURATION OR GREATER OVER PORTIONS OF THE SOUTHWEST TEXAS PANHANDLE...IF THE SFC LOW DEVELOPS JUST NORTHWEST OF THIS AREA AND RESULTS IN LOWER SPEEDS IN THE VICINITY. HOWEVER...AS EARLIER FORECASTER STATED...DO NOT WANT TO GET TOO CUTE IN TRYING TO PINPOINT AREAS THAT MAY BE SLIGHTLY BELOW CRITERIA. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 79 42 69 36 63 / 0 0 0 10 20 TULIA 81 42 68 35 59 / 0 0 0 10 30 PLAINVIEW 82 45 70 37 61 / 0 0 0 10 30 LEVELLAND 83 48 75 41 66 / 0 0 0 10 20 LUBBOCK 83 49 74 42 63 / 0 0 0 10 20 DENVER CITY 83 47 78 45 74 / 0 0 0 10 20 BROWNFIELD 84 49 77 43 70 / 0 0 0 10 30 CHILDRESS 80 51 71 40 60 / 10 10 10 10 60 SPUR 85 53 74 42 63 / 0 0 0 10 40 ASPERMONT 86 55 76 47 66 / 10 0 10 10 50 && .LUB WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 9 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: TXZ021>023-027>030-033>037-039>044. && $$ 23 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1045 AM CDT MON APR 7 2008 .UPDATE... 1045 AM CDT SUNDAY EVENING POSTFRONTAL WINDS OVER THE BIG COUNTRY BACKED RAPIDLY OVERNIGHT...SETTING UP THE MORNING DRYLINE NEAR THE NEW MEXICO BORDER. WITH SW/SSW WINDS ABOVE THE BOUNDARY LAYER...THERE WILL BE LITTLE MECHANICAL FORCING TO THE EAST. SOME MIXING PROPAGATION WILL OCCUR IN THE SUNNY AREAS TO THE WEST OF FWD CWA...BUT DRYLINE BULGE WILL LIKELY BE INTO SW OKLAHOMA. AS EXPECTED...NEW 12Z MODELS HAVE DIMINISHED THE EASTWARD PROGRESSION OF THE DRYLINE. RUC/NAM STILL GENERATING MUCAPES (1000-900MB) IN EXCESS OF 3000J/KG TO THE EAST OF THE BOUNDARY. WITH NEGLIGIBLE CONVERGENCE...BOUNDARY MOVEMENT ALONE MAY BE INSUFFICIENT TO REALIZE THIS EXTRAORDINARY INSTABILITY. ANY NEAR-BOUNDARY CONVECTIVE INITIATION THIS AFTERNOON WOULD BE WEST OF FWD CWA...WITH STORM MOTION TO THE NE. AS A RESULT...FAR NW ZONES MAY GET GRAZED...WITH NO OTHER IMPACTS THIS AFTERNOON. WILL MAINTAIN POP GRIDS AS IS...WITH SEVERE MENTION IN FAR NW...BUT ONLY 10 POPS THROUGHOUT THE REMAINDER OF RECENTLY EXPANDED SPC SLIGHT RISK AREA. OTHERWISE...ONLY MINOR ADJUSTMENTS TO HOURLY DATA TO ACCOUNT FOR CURRENT TRENDS. UPDATED IMAGES/PRODUCTS TO BE ISSUED SHORTLY. 25 && .AVIATION... 715 AM CDT /12Z TAFS/ MOISTURE HAS BEEN SLOW TO GET TO DFW AREA TAFS...SO VFR CONDITIONS HELD THROUGH THE NIGHT. HOWEVER...DO NOT WANT TO COMPLETELY PULL BR OUT OF TAFS BECAUSE IT IS CURRENTLY PATCHY ALL AROUND THE DFW TAF SITES. SO...LEFT BR IN BUT BACKED IT UP FROM 12Z TO 13Z. EXPECT IT TO SCATTER OUT RATHER QUICKLY BETWEEN 15Z/16Z AND RETURN TO VFR CONDITIONS. FURTHER SOUTH...IFR CONDITIONS HAVE BEEN STEADY SINCE 09Z AT ACT... DO NOT EXPECT MVFR CONDITIONS UNTIL AROUND 16Z. WINDS WILL INCREASE BY EARLY AFTERNOON AND CONTINUE THROUGH TOMORROW NIGHT. SKIES WILL BECOME OVC TOMORROW NIGHT AND REMAIN MVFR. VCTS WILL MOST LIKELY NEED TO BE ADDED LATE IN THE TAF PERIOD...BUT CONFIDENCE IS TOO LOW AT THIS TIME TO INCORPORATE INTO TAFS. 77/TDUD && .PREV DISCUSSION... 403 AM CDT THE 11-3.9 MICRON SATELLITE LOOPS SHOWS A LARGE AREA OF STRATUS FROM SOUTH CENTRAL AND SOUTHEAST TEXAS NORTH INTO THE EXTREME SOUTHERN PARTS OF NORTH TEXAS AS OF 08Z. THESE LOW CLOUDS WILL SPREAD NORTHWARD ACROSS MUCH OF NORTH TEXAS THIS MORNING ON A 35 KNOT LOW LEVEL JET. A WEAK COLD FRONT HAS SUNK SOUTH OF I-20...AND EXTENDED ALONG A BROWNWOOD...TO HILLSBORO...ATHENS LINE AS OF 08Z. THIS FRONT WILL LIFT BACK NORTH LATER TODAY AND A DRY LINE IS EXPECTED TO DEVELOP ACROSS WEST TEXAS. WE WILL BE CAPPED ACROSS NORTH TEXAS TODAY...HOWEVER...THUNDERSTORMS MAY FORM ACROSS SOUTHWEST OKLAHOMA INTO NORTHWEST TEXAS AHEAD OF THE DRYLINE. GIVEN THE FORECAST CAPES...AND STEEP LAPSE RATES...THERE WILL BE THE POTENTIAL FOR SOME SEVERE THUNDERSTORMS ACROSS THE NORTHWESTERN ZONES LATE THIS AFTERNOON AND ACROSS THE NORTH TONIGHT. THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS AREAWIDE TUESDAY AS A PACIFIC COLD FRONT ACROSS THE STATE. RAIN CHANCES WILL CONTINUE THROUGH THURSDAY WHEN A SHORTWAVE WILL MOVE ACROSS THE SOUTHERN PLAINS AND PUSH A STRONGER FRONT THROUGH NORTH TEXAS. DRY WEATHER IS THEN EXPECTED FRIDAY THROUGH THE WEEKEND. #58 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 81 65 78 54 67 / 10 20 40 50 50 WACO, TX 82 67 80 60 74 / 5 10 30 50 40 PARIS, TX 78 61 76 55 69 / 10 20 60 50 50 DENTON, TX 80 64 78 54 64 / 10 20 40 50 50 MCKINNEY, TX 78 63 77 56 68 / 10 20 40 50 50 DALLAS, TX 80 66 79 56 69 / 10 20 40 50 50 TERRELL, TX 82 65 78 58 72 / 5 20 40 50 50 CORSICANA, TX 81 64 81 61 75 / 5 10 40 50 40 TEMPLE, TX 82 65 81 62 79 / 5 10 30 40 40 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 26/25/84 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 100 PM CDT SUN APR 6 2008 .AVIATION... 100 PM CDT LOW CLOUDS HAVE DISSIPATED. A FEW CU THIS AFTERNOON...SCT CI/CS. WINDS WILL DIMINISH AS FRONT SURGES SOUTH INTO WEST TEXAS. STRATUS WILL RETURN...CIGS NEAR IFR...WITH SOME BR/HZ AROUND DAYBREAK. 25 && .UPDATE... 1028 AM CDT UPDATING FOR HOURLY TRENDS IN SKY/TEMPS/DEWPOINTS. MOISTURE HAS SURGED NORTHWARD EARLY THIS MORNING AND DEWPOINTS ARE RUNNING HIGHER THAN PREVIOUSLY FORECAST. OTHERWISE...HAVE RAISED HIGH TEMPS IN THE SW ZONES BASED ON RUC FORECASTS. SOUTH WINDS WILL INITIALLY BE A LITTLE BREEZY AROUND MIDDAY...BUT WILL BEGIN TO SUBSIDE AS A WEAK COLD FRONT MOVES INTO THE NW CWA AROUND SUNSET. WILL CONTINUE TO ASSESS ISOLATED SEVERE WEATHER POTENTIAL OVER THE NW ZONES FOR LATE TOMORROW AFTERNOON AS AIRMASS WILL BE VERY UNSTABLE WITH A DRY LINE MOVING INTO THE WESTERN ZONES. THEREAFTER...A RAINY/STORMY PATTERN WILL SET UP ACROSS NORTH TEXAS TUESDAY THROUGH THURSDAY. TR.92 && .AVIATION... 633 AM CDT /12Z TAFS/ STRATUS IS APPROACHING FROM THE SOUTH AND EAST RATHER RAPIDLY THIS MORNING. EXPECT CIGS BETWEEN 500 AND 1000 FEET BY DAYBREAK. VSBYS WILL ALSO BE REDUCED AT KACT AND POSSIBLY AT KAFW. CIGS SHOULD LIFT INTO MVFR CATEGORY BY 16Z...FINALLY SCATTERING OUT DURING THE EARLY TO MID AFTERNOON HOURS. EXPECT ANOTHER ROUND OF STRATUS TOMORROW MORNING. THANKS FOR COLLAB FORT WORTH CWSU. SCHULTZ && .UPDATE... 615 AM CDT LOW CLOUDS ARE SPREADING NORTHWARD INTO NORTH TEXAS ON A STRONG LOW LEVEL JET. HAVE SENT AN UPDATE TO INCLUDE MORNING LOW CLOUDS MAINLY ACROSS THE SOUTHEASTERN HALF OF NORTH TEXAS. THERE WILL ALSO BE AREAS OF FOG THROUGH MID MORNING UNDER THE CLOUD COVER. ALTHOUGH A FEW SITES ACROSS SOUTHEAST TEXAS ARE SEEING VISIBILITIES 1/2 MILE OR LESS...EXPECT VISIBILITIES ACROSS MOST OF NORTH TEXAS TO REMAIN ABOVE 1 MILE. #58 && .PREV DISCUSSION... 406 AM CDT A COLD FRONT THAT EXTENDS FROM NORTH CENTRAL KANSAS SOUTHWEST INTO EXTREME NORTHEASTERN NEW MEXICO AS OF 08Z...WILL MOVE INTO THE NORTHWESTERN PART OF NORTH TEXAS LATE THIS AFTERNOON. THIS FRONT WILL SINK FARTHER SOUTHEAST TO NEAR THE I-20 CORRIDOR TONIGHT BEFORE LIFTING BACK TO THE NORTH. AS A SHORTWAVE MOVES ACROSS THE CENTRAL ROCKIES...A DRY LINE WILL MOVE EAST INTO THE WESTERN PART OF NORTH TEXAS LATE MONDAY AFTERNOON. WE WILL SEE LOW CHANCES OF THUNDERSTORMS ACROSS THE EXTREME NORTHWEST MONDAY AFTERNOON...AND ACROSS THE NORTHERN THIRD MONDAY NIGHT. SOME OF THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE LARGE HAIL AND DAMAGING WINDS. A PACIFIC COLD FRONT WILL MOVE EAST ACROSS NORTH TEXAS TUESDAY. WE WILL SEE A CHANCE OF SHOWERS AND THUNDERSTORMS AREAWIDE AS THIS SYSTEM APPROACHES...AND ONCE AGAIN SOME OF THE STORMS MAY BE SEVERE. WE WILL CONTINUE TO SEE CHANCES OF SHOWERS AND THUNDERSTORMS WEDNESDAY AND THURSDAY BEFORE A STRONGER UPPER LEVEL SYSTEM MOVES FARTHER SOUTH AND PUSHES A STRONGER COLD FRONT THROUGH THE REGION. DRY WEATHER IS THEN EXPECTED FRIDAY THROUGH THE WEEKEND. #58 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 79 59 83 65 77 / 0 0 5 20 30 WACO, TX 82 59 83 66 80 / 0 0 5 10 40 PARIS, TX 74 54 80 61 76 / 0 5 10 20 50 DENTON, TX 80 56 82 63 75 / 0 0 10 20 30 MCKINNEY, TX 78 55 82 64 75 / 0 0 10 20 40 DALLAS, TX 79 59 82 66 79 / 0 0 5 20 30 TERRELL, TX 78 57 82 65 78 / 0 0 5 20 40 CORSICANA, TX 78 59 83 65 79 / 0 0 5 10 40 TEMPLE, TX 82 59 85 65 80 / 0 0 5 10 40 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 92/25 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 1028 AM CDT SUN APR 6 2008 .UPDATE... UPDATING FOR HOURLY TRENDS IN SKY/TEMPS/DEWPOINTS. MOISTURE HAS SURGED NORTHWARD EARLY THIS MORNING AND DEWPOINTS ARE RUNNING HIGHER THAN PREVIOUSLY FORECAST. OTHERWISE...HAVE RAISED HIGH TEMPS IN THE SW ZONES BASED ON RUC FORECASTS. SOUTH WINDS WILL INITIALLY BE A LITTLE BREEZY AROUND MIDDAY...BUT WILL BEGIN TO SUBSIDE AS A WEAK COLD FRONT MOVES INTO THE NW CWA AROUND SUNSET. WILL CONTINUE TO ASSESS ISOLATED SEVERE WEATHER POTENTIAL OVER THE NW ZONES FOR LATE TOMORROW AFTERNOON AS AIRMASS WILL BE VERY UNSTABLE WITH A DRY LINE MOVING INTO THE WESTERN ZONES. THEREAFTER...A RAINY/STORMY PATTERN WILL SET UP ACROSS NORTH TEXAS TUESDAY THROUGH THURSDAY. TR.92 && .PREV DISCUSSION... /ISSUED 633 AM CDT SUN APR 6 2008/ AVIATION... /12Z TAFS/ STRATUS IS APPROACHING FROM THE SOUTH AND EAST RATHER RAPIDLY THIS MORNING. EXPECT CIGS BETWEEN 500 AND 1000 FEET BY DAYBREAK. VSBYS WILL ALSO BE REDUCED AT KACT AND POSSIBLY AT KAFW. CIGS SHOULD LIFT INTO MVFR CATEGORY BY 16Z...FINALLY SCATTERING OUT DURING THE EARLY TO MID AFTERNOON HOURS. EXPECT ANOTHER ROUND OF STRATUS TOMORROW MORNING. THANKS FOR COLLAB FORT WORTH CWSU. SCHULTZ PREV DISCUSSION... /ISSUED 615 AM CDT SUN APR 6 2008/ UPDATE... LOW CLOUDS ARE SPREADING NORTHWARD INTO NORTH TEXAS ON A STRONG LOW LEVEL JET. HAVE SENT AN UPDATE TO INCLUDE MORNING LOW CLOUDS MAINLY ACROSS THE SOUTHEASTERN HALF OF NORTH TEXAS. THERE WILL ALSO BE AREAS OF FOG THROUGH MID MORNING UNDER THE CLOUD COVER. ALTHOUGH A FEW SITES ACROSS SOUTHEAST TEXAS ARE SEEING VISIBILITIES 1/2 MILE OR LESS...EXPECT VISIBILITIES ACROSS MOST OF NORTH TEXAS TO REMAIN ABOVE 1 MILE. #58 PREV DISCUSSION... /ISSUED 406 AM CDT SUN APR 6 2008/ DISCUSSION... A COLD FRONT THAT EXTENDS FROM NORTH CENTRAL KANSAS SOUTHWEST INTO EXTREME NORTHEASTERN NEW MEXICO AS OF 08Z...WILL MOVE INTO THE NORTHWESTERN PART OF NORTH TEXAS LATE THIS AFTERNOON. THIS FRONT WILL SINK FARTHER SOUTHEAST TO NEAR THE I-20 CORRIDOR TONIGHT BEFORE LIFTING BACK TO THE NORTH. AS A SHORTWAVE MOVES ACROSS THE CENTRAL ROCKIES...A DRY LINE WILL MOVE EAST INTO THE WESTERN PART OF NORTH TEXAS LATE MONDAY AFTERNOON. WE WILL SEE LOW CHANCES OF THUNDERSTORMS ACROSS THE EXTREME NORTHWEST MONDAY AFTERNOON...AND ACROSS THE NORTHERN THIRD MONDAY NIGHT. SOME OF THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE LARGE HAIL AND DAMAGING WINDS. A PACIFIC COLD FRONT WILL MOVE EAST ACROSS NORTH TEXAS TUESDAY. WE WILL SEE A CHANCE OF SHOWERS AND THUNDERSTORMS AREAWIDE AS THIS SYSTEM APPROACHES...AND ONCE AGAIN SOME OF THE STORMS MAY BE SEVERE. WE WILL CONTINUE TO SEE CHANCES OF SHOWERS AND THUNDERSTORMS WEDNESDAY AND THURSDAY BEFORE A STRONGER UPPER LEVEL SYSTEM MOVES FARTHER SOUTH AND PUSHES A STRONGER COLD FRONT THROUGH THE REGION. DRY WEATHER IS THEN EXPECTED FRIDAY THROUGH THE WEEKEND. #58 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 79 59 83 65 77 / 0 0 5 20 30 WACO, TX 82 59 83 66 80 / 0 0 5 10 40 PARIS, TX 74 54 80 61 76 / 0 5 10 20 50 DENTON, TX 80 56 82 63 75 / 0 0 10 20 30 MCKINNEY, TX 78 55 82 64 75 / 0 0 10 20 40 DALLAS, TX 79 59 82 66 79 / 0 0 5 20 30 TERRELL, TX 78 57 82 65 78 / 0 0 5 20 40 CORSICANA, TX 78 59 83 65 79 / 0 0 5 10 40 TEMPLE, TX 82 59 85 65 80 / 0 0 5 10 40 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 99/99 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1233 PM CDT MON APR 7 2008 .UPDATE...THIS AFTERNOON THE 07.12Z MODELS ARE IN GENERAL AGREEMENT THAT SOME PRECIPITATION WILL LINGER ACROSS NORTH CENTRAL WISCONSIN. THE SOUNDINGS INDICATE THAT THE BOUNDARY LAYER WILL BE WARM ENOUGH FOR A MIX OF RAIN AND SNOW. DUE TO THIS MIX...THERE SHOULD BE LITTLE...IF ANY...SNOW ACCUMULATIONS. && .PREV DISCUSSION... /ISSUED 546 AM CDT MON APR 7 2008/ UPDATE... SENT OUT UPDATED FORECAST FOR NRN FORECAST AREA NORTH OF HWY 10 IN CNTL WISCONSIN FOR INCREASED CHANCES FOR MESOSCALE BAND OF RAIN/DZL/SNOW THIS MORNING INTO EARLY AFTERNOON. LATEST RUNS OF NSSL-WRF...SPC 4KM WRF /NMM/...RUC13...NCAR 4KM WRF /ARW/ ALL SHOWING A NARROW BAND OF FRONTOGENETICALLY FORCED PCPN DEVELOPING THROUGH THE EARLY HOURS THIS MORNING ON THE NRN FRINGE OF THE INTENSE MID LEVEL CIRCULATION CURRENTLY MAKING ITS WAY ACROSS ERN MN. QUITE IMPRESSIVE QPF ON SOME RUNS...UP TOWARD A THIRD OF AN INCH. SOUNDINGS OFF RUC13 SHOWING DEPTH OF MOISTURE JUST BARELY REACHING -9C OR SO...MARGINAL FOR ICE INTRODUCTION. AND WITH BOUNDARY LAYER TEMPS COOLING INTO MID/UPPER 30S...THAT/S NOT OVERLY FAVORABLE FOR SNOW EITHER. SO IT MAY BE JUST LIGHT RAIN. HOWEVER...A LITTLE CONCERNED FOR A COOLER TEMP STRUCTURE /06Z NAM- WRF/ WHICH MAY PROMOTE ENOUGH ICE ALOFT FOR A MESOSCALE SNOW BAND OF ACCUMULATIONS ON GRASSY AREAS. MENTIONED SOME LIGHT ACCUMULATION...AND WE/LL JUST HAVE TO WATCH TO SEE HOW THIS UNFOLDS OVER THE NEXT 6 HOURS. BINAU PREV DISCUSSION... /ISSUED 333 AM CDT MON APR 7 2008/ SHORT TERM...THROUGH WEDNESDAY NIGHT TIME THIS MORNING SPENT ON REMNANTS OF FIRST POTENT MIDWEST SYSTEM CURRENTLY IN MN...SECOND ONE DUE IN TUESDAY...AND BIG SYSTEM LURKING IN THE EXTENDED PORTION. WARM WEEKEND TEMPERATURES A DISTANT MEMORY WITH WEEK OF BELOW NORMAL TEMPERATURES AND UNSETTLED WEATHER IN THE OFFING. CURRENTLY...ELONGATED AREA OF LOW PRESSURE OVER CNTL MN/NRN WI WITH PV ANOMALY ALOFT CURRENTLY APPROACHING WRN MSP AREA. RADAR MOSAICS/SATELLITE CAPTURE STRONG VORTICITY CENTER ASSOCIATED WITH THIS PV ANOMALY WITH SHRA/SHSN CIRCUMNAVIGATING THE CIRCULATION...AND ARM OF DEFORMATION/FRONTOGENETIC PCPN ACROSS NERN MN WHERE 2 FEET OF SNOW HAS FALLEN IN LAST 36 HOURS. LOCAL FORECAST AREA FEELING WESTERLY LOW LEVEL FLOW AS COLD FRONT SHIFTING THROUGH. PLENTY OF STRATOCUMULUS IN THE CRASHING THICKNESSES/TEMPERATURES WITH THE HEIGHT FALLS SHIFTING TOWARD THE AREA. WINDS GUSTY AS WELL SOUTH OF THE CIRCULATION. TODAY...EXPECT COMPACT MID/UPPER LEVEL LOW TO SHIFT EAST/NORTHEAST NORTH OF INTERSTATE 90 THIS MORNING. AREAS SOUTH OF I-90 WILL REMAIN IN SUBSIDENCE REGION OF THIS CYCLONE AND THUS NO POPS THIS MORNING. ALONG AND NORTH OF THE PV ANOMALY...ENOUGH Q/G FORCING AND PV ADVECTION TO MAINTAIN RAIN/SNOW SHOWER CHANCES ESPECIALLY THROUGH 15Z ACROSS AREAS OF CNTL WI NORTH OF HWY 10. TEMPERATURE STRUCTURE PROBLEMATIC THIS MORNING FOR P-TYPE...GIVEN EROSION OF THE VERY WARM WEEKEND AIRMASS...REPLACED WITH COOL ENOUGH TEMPS FOR SNOW. EXPECT ONE MORE BAND OF MIXED RAIN/SNOW SHOWERS TO DEVELOP IMMEDIATELY AHEAD OF 700-500MB LOW/CIRCULATION AS IT CROSSES FORECAST AREA THIS MORNING. WILL NOT RUN ANY ACCUMULATIONS AS EXPECT MOST OF IT WILL BE RAIN...BUT WILL WATCH CLOSELY. LARGE AREA OF STRATOCUMULUS AND BREEZY WESTERLY WINDS GUARANTEE A RATHER RAW DAY WITH HIGHS IN THE 40S. MAY SEE SPRINKLES/FLURRIES THROUGH THE AFTERNOON AND THE BOUNDARY LAYER MIXES DEEPER AND LOW LEVEL INSTABILITY DEVELOPS. BETTER CHANCES OF SUNSHINE REMAIN ALONG THE FAR SWRN/SRN PERIPHERY OF FORECAST AREA TODAY. TONIGHT...A LITTLE MOMENT TO CATCH OUR BREATH IN BETWEEN SYSTEMS. CLEARING OVER SRN FORECAST AREA WILL WORK NORTH/EAST WITH SHORTWAVE RIDGING. VERY LATE IN THE NIGHT...EXPECT RAIN/STORMS TO BLOSSOM OVER KS/MO/SERN NEB AS NEXT POTENT WAVE EJECTS OUT OF HIGH PLAINS WITH STRONG RETURN FLOW DEVELOPING ON 50KT LOW LEVEL JET INTO DEVELOPING CYCLONE OVER ERN KS. CUT BACK POPS FURTHER AS THIS SYSTEM/S EVOLUTION HAS SLOWED A BIT...AND NOW HAVE ONLY VERY SMALL POPS IN FAR SRN AREAS LATER TONIGHT. TUES/TUES NIGHT...RAPIDLY INTENSIFYING/EXPANDING AREA OF RAIN/STORMS WILL MOVE OUT OF HIGH PLAINS INTO IOWA AND SWRN WISCONSIN TUES MORNING. STILL SEEING MODEL ISSUES HERE...BUT SEEING A COMMON THEME IN 07.00Z CMC/ECMWF/SREF/GEFS MEAN FOR MAIN QPF AXIS TO BE LAID OUT ACROSS ERN IOWA/NRN IL/SRN WI. 07.00Z NAM- WRF ON NWRN SIDE OF DATASETS WITH HEAVIER QPF ACROSS MOST OF ARX FORECAST AREA...AND TRENDED FORECAST HEAVILY TOWARD SREF/ECMWF COMBINATION. HENCE...EXPECT BLOSSOMING RAIN AREA TO MOVE NORTH/EAST INTO NORTHEAST IA/SWRN WI WITH MOD INTENSITY. WITH STRONG MID LEVEL WAVE DEEPENING AS IT TREKS ACROSS NRN MN...SFC LOW WILL DEEPEN IN RESPONSE AS IT MOVES FROM ILLINOIS INTO MICHIGAN BY WEDNESDAY MORNING. SREF/ECMWF IN GOOD AGREEMENT THAT BEST MOISTURE TRANSPORT/CONVERGENCE SIGNAL WILL POINT THE HEAVY RAIN AXIS ACROSS OUR SERN FORECAST AREA /SWRN WISCONSIN/ WITH LIGHTER INTENSITY RAINS FURTHER NORTH/WEST. PEAK ISENTROPIC ASCENT/WARM ADVECTION ON TUES AFTN/EVENING SHOULD BRING THE HEAVIEST PCPN RATE. WILL NEED TO WATCH FOR DEVELOPING DEFORMATION /FRONTOGENETIC/ BAND OF PCPN ACROSS HEART OF FORECAST AREA. IF THIS GETS GOING IN EARNEST...THERMAL STRUCTURE WILL INDEED BE SUPPORTIVE OF A CHANGE TO SNOW TUESDAY NIGHT...AND POTENTIAL FOR ACCUMULATIONS OF AT LEAST A SEVERAL INCHES. 07.00Z NAM IS HEAVILY TOWARD THIS SCENARIO...BUT WITHOUT SUPPORT FROM ECMWF/SREF/GFS. BE THAT AS IT MAY...EVEN USING NON-NAM SOLNS BRINGS AN ACCUMULATING SNOW POTENTIAL FOR THE LIGHTER PCPN TUESDAY NIGHT...AND AM RUNNING SOME LIGHT ACCUMS AS A RESULT. VERY IFFY HERE...THOUGH...WITH LOWER CONFIDENCE GIVEN TIME OF YEAR AND QUESTIONABLE RATES FOR GOOD ACCUMULATION ON WARM SOILS. WILL NEED TO CONTINUE TO WATCH THIS CLOSELY...AS DEEP ISOTHERMAL LAYER ON SOUNDINGS CLOSE TO 0C LENDS A NOTION IT WON/T TAKE MUCH CHANGE IN DYNAMICS OR TRACK OF SYSTEM TO GO TOWARD A MORE SNOW SCENARIO. COULD SEE UP AN INCH OF RAIN IN FAR SERN FORECAST AREA...SO NEED TO WATCH RIVER RISES TOO. SYSTEM CLEARS BY WEDNESDAY MORNING WITH A DRY DAY IN STORE...REMAINING COOL HOWEVER. LONG TERM...THURSDAY THROUGH SUNDAY DEEP UPPER LOW/LONGWAVE TROUGH TO AFFECT THE FORECAST AREA THIS PERIOD...ESPECIALLY THURS-SAT. PERIOD WILL BE CHARACTERIZED BY WELL BELOW NORMAL TEMPERATURES...POTENTIALLY HEAVY PRECIPITATION AMOUNTS...AND THREATS RUNNING FROM ACCUMULATING SNOW...TO FLOODING. NEW 07.00Z ECMWF AND GEFS MEAN IN EXCELLENT AGREEMENT ON TIMING A SLOWER SYSTEM THAN GFS/CMC. STRONG SHORTWAVE ENERGY IN THE BASE OF ANOMALOUSLY DEEP LONGWAVE TROUGH IN THE SPINE OF ROCKIES ON THURSDAY SWINGS NORTHEAST AND BECOMES NEGATIVELY TILTED WITH DEEP CYCLOGENESIS OVER THE MIDWEST. UPPER SYSTEM EVOLVES INTO A MATURE CLOSED/STACKED CYCLONE BY FRIDAY /ECMWF/...AND MOVES ONLY VERY SLOWLY ACROSS UPPER MS VALLEY THROUGH SATURDAY. DETERMINISTIC 500MB HEIGHTS AROUND 530DM /ECMWF/ ARE APPROACHING 3 STANDARD DEVIATIONS BELOW CLIMATOLOGY...AND IS ON THE DEEPER END OF THE SPECTRUM. ARRIVAL OF SYSTEM ON THURSDAY/THURSDAY NIGHT ACCOMPANIED BY FORCING VIA JET/PV ADVECTION. VERY DIFFLUENT ALOFT. SHOULD SEE WIDESPREAD RAINS/CONVECTION WHICH COULD BE HEAVY. 07.00Z GFS AND CMC...ALTHOUGH STRONG...ARE A LITTLE WEAKER AND MORE PROGRESSIVE WITH EVOLUTION OF THE SFC/UPPER LEVEL LOWS. ALL MODELS BRING GOOD QPF THURS NIGHT INTO EARLY FRIDAY WHICH IS ALREADY HANDLED IN FORECAST. MAY NEED TO EXTEND HIGH RAIN CHANCES FURTHER INTO WEEKEND GIVEN 07.00Z ECMWF/GEFS MEAN. IF THE STRONGER/MORE NEGATIVE TILT ECMWF VERIFIES...MORE OF A HEAVY RAIN/FLOODING THREAT AND PERHAPS EVEN SEVERE THREAT GIVEN SURFACE LOW WEST OF FORECAST AREA. WEAKER CANADIAN/GFS HAVE A HIGHER THREAT OF ACCUMULATING SNOW WITH SFC LOW SOUTH OF AREA. ALL MODELS TRENDING SLOWER WITH LINGERING RAIN/SNOW THREATS INTO BULK OF WEEKEND. AVIATION... AN AREA OF LOW PRESSURE WILL CONTINUE TO TRACK NORTHEAST TODAY...EXITING OVER LAKE SUPERIOR BY THIS EVENING. MOISTURE WRAPPED AROUND THE LOW SHOULD KEEP THE KRST/KLSE TAF SITES UNDER AN MVFR OVC/BKN CEILING THROUGH MOST OF TODAY. SOME IFR CEILINGS LOOK POSSIBLE PER THE LATEST SURFACE OBS OVER CENTRAL MN...BUT WOULD LIKELY JUST AFFECT KRST. IN ADDITION TO THE CLOUDS...A TROUGH EXTENDING WEST OF THE SFC LOW WILL PROMOTE SOME SCT -RN/SN SHOWERS THIS MORNING...BUT MAYBE NOT ENOUGH TO INCLUDE IN THE TAFS. WEAK HIGH PRESSURE WILL BUILD IN THIS EVENING...PROMOTING SOME CLEARING ACROSS IA/ILL. HOWEVER...LOW LEVEL MOISTURE REMAINS ABUNDANT NORTH OF THERE...AND WOULD TREND TOWARD KEEPING MVFR CEILINGS THROUGH THE NIGHT. THIS SCENARIO HAS THE MOST SUPPORT...SO WILL LEAN THE TAFS TOWARD THIS. CLEARING WILL BE CLOSE THOUGH. TUES WILL BRING ANOTHER LOW INTO THE REGION...WITH THICKENING CLOUDS AND THEN LIKELY PCPN BY LATE AFTERNOON. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE - BOYNE PREV FORECAST - BINAU wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 546 AM CDT MON APR 7 2008 .UPDATE... SENT OUT UPDATED FORECAST FOR NRN FORECAST AREA NORTH OF HWY 10 IN CNTL WISCONSIN FOR INCREASED CHANCES FOR MESOSCALE BAND OF RAIN/DZL/SNOW THIS MORNING INTO EARLY AFTERNOON. LATEST RUNS OF NSSL-WRF...SPC 4KM WRF /NMM/...RUC13...NCAR 4KM WRF /ARW/ ALL SHOWING A NARROW BAND OF FRONTOGENETICALLY FORCED PCPN DEVELOPING THROUGH THE EARLY HOURS THIS MORNING ON THE NRN FRINGE OF THE INTENSE MID LEVEL CIRCULATION CURRENTLY MAKING ITS WAY ACROSS ERN MN. QUITE IMPRESSIVE QPF ON SOME RUNS...UP TOWARD A THIRD OF AN INCH. SOUNDINGS OFF RUC13 SHOWING DEPTH OF MOISTURE JUST BARELY REACHING -9C OR SO...MARGINAL FOR ICE INTRODUCTION. AND WITH BOUNDARY LAYER TEMPS COOLING INTO MID/UPPER 30S...THAT/S NOT OVERLY FAVORABLE FOR SNOW EITHER. SO IT MAY BE JUST LIGHT RAIN. HOWEVER...A LITTLE CONCERNED FOR A COOLER TEMP STRUCTURE /06Z NAM- WRF/ WHICH MAY PROMOTE ENOUGH ICE ALOFT FOR A MESOSCALE SNOW BAND OF ACCUMULATIONS ON GRASSY AREAS. MENTIONED SOME LIGHT ACCUMULATION...AND WE/LL JUST HAVE TO WATCH TO SEE HOW THIS UNFOLDS OVER THE NEXT 6 HOURS. BINAU && .PREV DISCUSSION... /ISSUED 333 AM CDT MON APR 7 2008/ SHORT TERM...THROUGH WEDNESDAY NIGHT TIME THIS MORNING SPENT ON REMNANTS OF FIRST POTENT MIDWEST SYSTEM CURRENTLY IN MN...SECOND ONE DUE IN TUESDAY...AND BIG SYSTEM LURKING IN THE EXTENDED PORTION. WARM WEEKEND TEMPERATURES A DISTANT MEMORY WITH WEEK OF BELOW NORMAL TEMPERATURES AND UNSETTLED WEATHER IN THE OFFING. CURRENTLY...ELONGATED AREA OF LOW PRESSURE OVER CNTL MN/NRN WI WITH PV ANOMALY ALOFT CURRENTLY APPROACHING WRN MSP AREA. RADAR MOSAICS/SATELLITE CAPTURE STRONG VORTICITY CENTER ASSOCIATED WITH THIS PV ANOMALY WITH SHRA/SHSN CIRCUMNAVIGATING THE CIRCULATION...AND ARM OF DEFORMATION/FRONTOGENETIC PCPN ACROSS NERN MN WHERE 2 FEET OF SNOW HAS FALLEN IN LAST 36 HOURS. LOCAL FORECAST AREA FEELING WESTERLY LOW LEVEL FLOW AS COLD FRONT SHIFTING THROUGH. PLENTY OF STRATOCUMULUS IN THE CRASHING THICKNESSES/TEMPERATURES WITH THE HEIGHT FALLS SHIFTING TOWARD THE AREA. WINDS GUSTY AS WELL SOUTH OF THE CIRCULATION. TODAY...EXPECT COMPACT MID/UPPER LEVEL LOW TO SHIFT EAST/NORTHEAST NORTH OF INTERSTATE 90 THIS MORNING. AREAS SOUTH OF I-90 WILL REMAIN IN SUBSIDENCE REGION OF THIS CYCLONE AND THUS NO POPS THIS MORNING. ALONG AND NORTH OF THE PV ANOMALY...ENOUGH Q/G FORCING AND PV ADVECTION TO MAINTAIN RAIN/SNOW SHOWER CHANCES ESPECIALLY THROUGH 15Z ACROSS AREAS OF CNTL WI NORTH OF HWY 10. TEMPERATURE STRUCTURE PROBLEMATIC THIS MORNING FOR P-TYPE...GIVEN EROSION OF THE VERY WARM WEEKEND AIRMASS...REPLACED WITH COOL ENOUGH TEMPS FOR SNOW. EXPECT ONE MORE BAND OF MIXED RAIN/SNOW SHOWERS TO DEVELOP IMMEDIATELY AHEAD OF 700-500MB LOW/CIRCULATION AS IT CROSSES FORECAST AREA THIS MORNING. WILL NOT RUN ANY ACCUMULATIONS AS EXPECT MOST OF IT WILL BE RAIN...BUT WILL WATCH CLOSELY. LARGE AREA OF STRATOCUMULUS AND BREEZY WESTERLY WINDS GUARANTEE A RATHER RAW DAY WITH HIGHS IN THE 40S. MAY SEE SPRINKLES/FLURRIES THROUGH THE AFTERNOON AND THE BOUNDARY LAYER MIXES DEEPER AND LOW LEVEL INSTABILITY DEVELOPS. BETTER CHANCES OF SUNSHINE REMAIN ALONG THE FAR SWRN/SRN PERIPHERY OF FORECAST AREA TODAY. TONIGHT...A LITTLE MOMENT TO CATCH OUR BREATH IN BETWEEN SYSTEMS. CLEARING OVER SRN FORECAST AREA WILL WORK NORTH/EAST WITH SHORTWAVE RIDGING. VERY LATE IN THE NIGHT...EXPECT RAIN/STORMS TO BLOSSOM OVER KS/MO/SERN NEB AS NEXT POTENT WAVE EJECTS OUT OF HIGH PLAINS WITH STRONG RETURN FLOW DEVELOPING ON 50KT LOW LEVEL JET INTO DEVELOPING CYCLONE OVER ERN KS. CUT BACK POPS FURTHER AS THIS SYSTEM/S EVOLUTION HAS SLOWED A BIT...AND NOW HAVE ONLY VERY SMALL POPS IN FAR SRN AREAS LATER TONIGHT. TUES/TUES NIGHT...RAPIDLY INTENSIFYING/EXPANDING AREA OF RAIN/STORMS WILL MOVE OUT OF HIGH PLAINS INTO IOWA AND SWRN WISCONSIN TUES MORNING. STILL SEEING MODEL ISSUES HERE...BUT SEEING A COMMON THEME IN 07.00Z CMC/ECMWF/SREF/GEFS MEAN FOR MAIN QPF AXIS TO BE LAID OUT ACROSS ERN IOWA/NRN IL/SRN WI. 07.00Z NAM- WRF ON NWRN SIDE OF DATASETS WITH HEAVIER QPF ACROSS MOST OF ARX FORECAST AREA...AND TRENDED FORECAST HEAVILY TOWARD SREF/ECMWF COMBINATION. HENCE...EXPECT BLOSSOMING RAIN AREA TO MOVE NORTH/EAST INTO NORTHEAST IA/SWRN WI WITH MOD INTENSITY. WITH STRONG MID LEVEL WAVE DEEPENING AS IT TREKS ACROSS NRN MN...SFC LOW WILL DEEPEN IN RESPONSE AS IT MOVES FROM ILLINOIS INTO MICHIGAN BY WEDNESDAY MORNING. SREF/ECMWF IN GOOD AGREEMENT THAT BEST MOISTURE TRANSPORT/CONVERGENCE SIGNAL WILL POINT THE HEAVY RAIN AXIS ACROSS OUR SERN FORECAST AREA /SWRN WISCONSIN/ WITH LIGHTER INTENSITY RAINS FURTHER NORTH/WEST. PEAK ISENTROPIC ASCENT/WARM ADVECTION ON TUES AFTN/EVENING SHOULD BRING THE HEAVIEST PCPN RATE. WILL NEED TO WATCH FOR DEVELOPING DEFORMATION /FRONTOGENETIC/ BAND OF PCPN ACROSS HEART OF FORECAST AREA. IF THIS GETS GOING IN EARNEST...THERMAL STRUCTURE WILL INDEED BE SUPPORTIVE OF A CHANGE TO SNOW TUESDAY NIGHT...AND POTENTIAL FOR ACCUMULATIONS OF AT LEAST A SEVERAL INCHES. 07.00Z NAM IS HEAVILY TOWARD THIS SCENARIO...BUT WITHOUT SUPPORT FROM ECMWF/SREF/GFS. BE THAT AS IT MAY...EVEN USING NON-NAM SOLNS BRINGS AN ACCUMULATING SNOW POTENTIAL FOR THE LIGHTER PCPN TUESDAY NIGHT...AND AM RUNNING SOME LIGHT ACCUMS AS A RESULT. VERY IFFY HERE...THOUGH...WITH LOWER CONFIDENCE GIVEN TIME OF YEAR AND QUESTIONABLE RATES FOR GOOD ACCUMULATION ON WARM SOILS. WILL NEED TO CONTINUE TO WATCH THIS CLOSELY...AS DEEP ISOTHERMAL LAYER ON SOUNDINGS CLOSE TO 0C LENDS A NOTION IT WON/T TAKE MUCH CHANGE IN DYNAMICS OR TRACK OF SYSTEM TO GO TOWARD A MORE SNOW SCENARIO. COULD SEE UP AN INCH OF RAIN IN FAR SERN FORECAST AREA...SO NEED TO WATCH RIVER RISES TOO. SYSTEM CLEARS BY WEDNESDAY MORNING WITH A DRY DAY IN STORE...REMAINING COOL HOWEVER. LONG TERM...THURSDAY THROUGH SUNDAY DEEP UPPER LOW/LONGWAVE TROUGH TO AFFECT THE FORECAST AREA THIS PERIOD...ESPECIALLY THURS-SAT. PERIOD WILL BE CHARACTERIZED BY WELL BELOW NORMAL TEMPERATURES...POTENTIALLY HEAVY PRECIPITATION AMOUNTS...AND THREATS RUNNING FROM ACCUMULATING SNOW...TO FLOODING. NEW 07.00Z ECMWF AND GEFS MEAN IN EXCELLENT AGREEMENT ON TIMING A SLOWER SYSTEM THAN GFS/CMC. STRONG SHORTWAVE ENERGY IN THE BASE OF ANOMALOUSLY DEEP LONGWAVE TROUGH IN THE SPINE OF ROCKIES ON THURSDAY SWINGS NORTHEAST AND BECOMES NEGATIVELY TILTED WITH DEEP CYCLOGENESIS OVER THE MIDWEST. UPPER SYSTEM EVOLVES INTO A MATURE CLOSED/STACKED CYCLONE BY FRIDAY /ECMWF/...AND MOVES ONLY VERY SLOWLY ACROSS UPPER MS VALLEY THROUGH SATURDAY. DETERMINISTIC 500MB HEIGHTS AROUND 530DM /ECMWF/ ARE APPROACHING 3 STANDARD DEVIATIONS BELOW CLIMATOLOGY...AND IS ON THE DEEPER END OF THE SPECTRUM. ARRIVAL OF SYSTEM ON THURSDAY/THURSDAY NIGHT ACCOMPANIED BY FORCING VIA JET/PV ADVECTION. VERY DIFFLUENT ALOFT. SHOULD SEE WIDESPREAD RAINS/CONVECTION WHICH COULD BE HEAVY. 07.00Z GFS AND CMC...ALTHOUGH STRONG...ARE A LITTLE WEAKER AND MORE PROGRESSIVE WITH EVOLUTION OF THE SFC/UPPER LEVEL LOWS. ALL MODELS BRING GOOD QPF THURS NIGHT INTO EARLY FRIDAY WHICH IS ALREADY HANDLED IN FORECAST. MAY NEED TO EXTEND HIGH RAIN CHANCES FURTHER INTO WEEKEND GIVEN 07.00Z ECMWF/GEFS MEAN. IF THE STRONGER/MORE NEGATIVE TILT ECMWF VERIFIES...MORE OF A HEAVY RAIN/FLOODING THREAT AND PERHAPS EVEN SEVERE THREAT GIVEN SURFACE LOW WEST OF FORECAST AREA. WEAKER CANADIAN/GFS HAVE A HIGHER THREAT OF ACCUMULATING SNOW WITH SFC LOW SOUTH OF AREA. ALL MODELS TRENDING SLOWER WITH LINGERING RAIN/SNOW THREATS INTO BULK OF WEEKEND. AVIATION... AN AREA OF LOW PRESSURE WILL CONTINUE TO TRACK NORTHEAST TODAY...EXITING OVER LAKE SUPERIOR BY THIS EVENING. MOISTURE WRAPPED AROUND THE LOW SHOULD KEEP THE KRST/KLSE TAF SITES UNDER AN MVFR OVC/BKN CEILING THROUGH MOST OF TODAY. SOME IFR CEILINGS LOOK POSSIBLE PER THE LATEST SURFACE OBS OVER CENTRAL MN...BUT WOULD LIKELY JUST AFFECT KRST. IN ADDITION TO THE CLOUDS...A TROUGH EXTENDING WEST OF THE SFC LOW WILL PROMOTE SOME SCT -RN/SN SHOWERS THIS MORNING...BUT MAYBE NOT ENOUGH TO INCLUDE IN THE TAFS. WEAK HIGH PRESSURE WILL BUILD IN THIS EVENING...PROMOTING SOME CLEARING ACROSS IA/ILL. HOWEVER...LOW LEVEL MOISTURE REMAINS ABUNDANT NORTH OF THERE...AND WOULD TREND TOWARD KEEPING MVFR CEILINGS THROUGH THE NIGHT. THIS SCENARIO HAS THE MOST SUPPORT...SO WILL LEAN THE TAFS TOWARD THIS. CLEARING WILL BE CLOSE THOUGH. TUES WILL BRING ANOTHER LOW INTO THE REGION...WITH THICKENING CLOUDS AND THEN LIKELY PCPN BY LATE AFTERNOON. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ 01/01 wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 416 AM CDT SUN APR 6 2008 .SHORT TERM...THROUGH TUESDAY NIGHT BEGINNING OF VERY UNSETTLED PERIOD IN THE WEATHER BEGINS TODAY WITH FIRST OF 3 POTENT SYSTEMS TO MOVE THROUGH THE AREA. SECOND SYSTEM TUESDAY/TUESDAY NIGHT WAS A PRIMARY FOCUS TONIGHT...AS WELL AS RAIN CHANCES TODAY. NICE SPRING WARMTH HANGS ON ONE MORE DAY...BEFORE BACK BELOW NORMAL FOR REST OF THE WEEK. CURRENTLY...EFFECTS OF FIRST POTENT UPPER TROUGH /OVER WRN SD PER WATER VAPOR LOOP/RUC ANALYSIS/ STARTING TO BE SEEN IN OBSERVATIONAL DATASETS. BROAD SLY FLOW IN WARM SECTOR OVER FORECAST AREA...WITH TEMPERATURES VERY SLOW TO FALL OVERNIGHT WITH 40S/50S ACROSS THE AREA. SHARP FRONTAL BOUNDARY FROM BROOKINGS/WATERTOWN SD NORTHEAST TO HAYWARD WI WITH BANDS OF CONVECTIVE SNOW NORTH OF THIS FRONT OVER NERN MN. WEAKER LEAD SHORTWAVE OVER SERN NEB KICKING OFF ELEVATED SHOWERS/THUNDER IN THIS AREA PER KOAX RADAR. LARGE VEIL OF MID/HIGH CLOUDS OVER THE AREA. ANOTHER IMPRESSIVE WAVE UPSTREAM OVER NERN PACIFIC...WHICH IS TUESDAY/S SYSTEM. TODAY/TONIGHT...THINKING HERE HAS NOT CHANGED ALL TOO MUCH...WITH SEVERAL WAVES OF PCPN IN THE WARM SECTOR OF THIS CYCLONE WHICH WILL MOVE/DEVELOP NORTHEAST ALONG THE SHARP FRONTAL ZONE IN RESPONSE TO HEIGHT FALLS ALOFT MOVING ACROSS SD/MN TODAY. INITIAL WAVE OVER SERN NEB THIS MORNING WILL RAPIDLY SHIFT NORTHEAST INTO SRN MN BY LATE THIS MORNING...AND ALL HI-RES WRF MODELS /NSSL...4KM SPC NMM...4KM NCAR ARW...AND LOCAL ARF-WRF/ EXPAND CURRENT ELEVATED ACTIVITY OVER SERN NEB INTO NRN IA/SRN MN LATER THIS MORNING. QUESTIONS HOW FAR EAST THIS WILL MAKE IT...SO RAN HIGHER POPS THIS MORNING IN I-35 CORRIDOR...DECREASING TOWARD MS RIVER. AS CYCLONE DEEPENS/LIFTS NORTHEAST TODAY...MAIN PV ANOMALY ALOFT AND Q/G FORCING OVERSPREADS SHARPENING COLD FRONTAL ZONE AS IT SHIFTS EAST TOWARD MS RIVER THIS AFTN/EVENING. SHOULD SEE NARROW BAND OF SHRA/ISOLD TSRA DEVELOP WITH TIME IN ASSOCIATION WITH THIS FEATURE...ESPECIALLY ALONG/NORTH OF INTERSTATE 90 CLOSER TO PARENT DYNAMICS ALOFT. RAIN AMOUNTS OVERALL WITH THIS SYSTEM WILL BE QUARTER INCH OR LESS...BUT A FEW EMBEDDED CONVECTIVE ELEMENTS MAY DROP UP TO A HALF INCH EAST OF MS RIVER THIS EVENING. AS STRONG SUBSIDENCE SIGNAL BECOMES DEFINED IN Q/G FIELDS OVERNIGHT...SHOULD SEE RAPID END IN PCPN FROM SW-NE THROUGH THE NIGHT. TAILORED POPS/TIMING IN THIS FASHION. A QUIET MONDAY/MONDAY NIGHT IN SHORTWAVE RIDGING BEHIND THIS SYSTEM. MAYBE A FEW SPRINKLES/SNOW SHOWERS IN STEEPER LAPSE RATE REGION/STRATOCUMULUS ON MONDAY MORNING OVER NRN AREAS...AND MUCH COOLER. NEXT ISSUE...A RATHER SIGNIFICANT ONE...IS EVEN MORE DYNAMIC WAVE FOR TUESDAY/TUESDAY NIGHT WITH IMPACTS SHIFTING INTO THE LOCAL AREA. REALLY A LOWER CONFIDENCE FORECAST HERE GIVEN BACK-AND-FORTH DEPICTION OF DEPTH/INTENSITY OF TROPOSPHERIC WAVE AND SFC LOW. 06.00Z GFS/CMC DEFINITELY IN ONE CAMP WHICH IS A WEAKER/MORE OPEN WAVE SLIDING SOUTH/EAST OF THE AREA WITH BAND OF RAIN/SNOW TUES AFTN/EVENING OVER THE SOUTH/EAST...NOT A HIGH IMPACT. 06.00Z ECMWF BACK TO VERY DYNAMIC/CLOSED UPPER LOW AND DEEP SFC LOW MOVING THROUGH IL/WI WITH SIG QPF EVENT...SOME OF WHICH UNDOUBTEDLY WOULD BE HEAVY SNOW GIVEN CRASHING THICKNESSES/THERMAL STRUCTURE IN HEAVY DEFORMATION ZONE PCPN. QPF DIFFERENCES FROM THESE 3 GLOBAL MODELS IS VERY DIFFERENT FOR THE AREA...LITTLE TO NONE ON 06.00Z CMC...LESS THAN A HALF INCH ON 06.00Z GFS...AND 1.0-1.5 INCHES ON 06.00Z ECMWF. 06.03Z SREF QPF ON THE HEAVIER SIDE...WHICH RAISES FLAG THAT ECMWF MAY BE MORE CORRECT HERE...AND THIS CERTAINLY SEEN IN MREF PLUMES WHERE A GOOD NUMBER OF RUNS ARE TOWARD THE HEAVIER AMOUNTS. THIS SYSTEM HAS CERTAINLY BEEN DEPICTED AS A DEEP/CLOSED SYSTEM UNTIL LAST NIGHTS 05.06Z GFS AND SUBSEQUENT RUNS. SO THE BOTTOMLINE...IS THAT CONFIDENCE IS LOW...SO MAINTAINED BROAD AREA OF LIKELY POPS FOR TUESDAY/TUESDAY NIGHT ON THE SOUTH/EAST HALF OF FORECAST AREA. THERE IS DEFINITELY A HEAVY SNOW THREAT HERE...AND THIS BEARS OUT IN HPC DAY3 SNOW RISKS. GIVEN VERY MARGINAL THERMAL STRUCTURE IN THE BOUNDARY LAYER...THE DIFFERING TRACKS...AND THE FACT IT WILL BE APRIL 8TH...THERE IS A LOT GOING AGAINST A HEAVY SNOW EVENT. HOWEVER...SOUNDINGS DO INDEED SUPPORT SNOW FROM A WIDE ASSORTMENT OF MODELS...AND IF HEAVY QPF MATERIALIZES...WILL NEED TO REMAIN OPEN TO THIS POTENTIAL. IF ONLY RAIN WERE TO FALL...WE MAY BE DEALING WITH FLOOD ISSUES GIVEN RIVERS RUNNING A LITTLE ON HIGH SIDE GIVEN LAST SOAK A FEW DAYS AGO. .LONG TERM...WEDNESDAY THROUGH SATURDAY FOCUS IN THE EXTENDED PORTION SQUARELY ON VERY LARGE/POTENT UPPER TROUGH AND SFC CYCLONE SET TO DEVELOP/MOVE NORTHEAST INTO THE AREA ON THURSDAY INTO THE FIRST HALF OF THE WEEKEND WITH POTENTIAL FOR NUMEROUS THREATS...HEAVY RAIN...RUNOFF...THUNDERSTORMS...HEAVY SNOW...ALL DEPENDENT ON TRACK OF SFC LOW. ALL LONGER RANGE GUIDANCE INCREASING CONSENSUS THAT THIS SYSTEM WILL IMPACT CNTL CONUS AND LOCAL AREA...SO POPS WILL NEED TO BE RAISED FURTHER IN COMING SHIFTS. CERTAINLY POTENTIAL FOR SYNOPTIC HEAVY RAINFALL EVENT IN WARM SECTOR PER MODEL QPFS...AND STRONG KINEMATICS/THERMODYNAMICS. OR THE CONTRARY...A LATE SEASON HEAVY SNOW EVENT IN THE DEFORMATION ZONE WITH PLENTY COLD ENOUGH AIR AND DYNAMIC COOLING FOR THIS STRIPE OF WINTRY PRECIPITATION. AS USUAL...THERE ARE TIMING/TRACK DIFFERENCES HERE WITH 06.00Z ECMWF QUICKER/STRONGER WITH SFC LOW THROUGH HEART OF FORECAST AREA THURS NIGHT AND FRIDAY. GFS FURTHER SOUTH/EAST AND SLOWER...AND THIS VERY IMPORTANT TO P-TYPE AND MAX QPF AXIS WITHIN THE RESPECTIVE MODELS. 06.00Z CMC MUCH CLOSER TO 06.00Z GFS/GEFS MEAN. ALSO IN PLAY HERE WITH SUCH A DEEP SYSTEM IS DRY SLOT. REGARDLESS....NEED TO WATCH THIS MONSTER SYSTEM CLOSELY GIVEN POTENTIAL IMPACTS RANGING FROM WINTER STORM TO HEAVY RAIN TO SEVERE WEATHER...ALL DEPENDENT ON EVOLUTION OF UPPER TROUGH/SFC LOW TRACK. ALSO...WOULD SEEM FRI/SAT TEMPERATURES TOO OPTIMISTIC RIGHT NOW GIVEN PCPN POTENTIAL AND AMOUNT OF COLD AIR LURKING. AS OF NOW...MADE NO CHANGES TO CURRENT FORECAST...BUT DO SEE INCREASE IN POPS WARRANTED PARTICULARLY THURS NIGHT/FRIDAY. && .AVIATION... HIGH...THIN CLOUDS WILL COVER THE AREA THROUGH MUCH OF TODAY...WITH CEILINGS GRADUALLY LOWERING AND THICKENING AS A COLD FRONT APPROACHES FROM THE WEST. THIS FRONT WILL MOVE ACROSS THE REGION BETWEEN 00-06Z...BRINGING A THREAT FOR SOME -SHRA/TSRA...ALTHOUGH THE THUNDER POSSIBILITIES LOOK SMALL DUE TO LIMITED INSTABILITY. GUSTY NORTHWEST WINDS POST THE FRONT WILL PERSIST INTO SUNDAY...GRADUALLY SUBSIDING BY SUNDAY NIGHT AS AN AREA OF HIGH PRESSURE BUILDS IN FROM THE NORTHERN PLAINS && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...BINAU AVIATION...RIECK wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 325 AM EDT TUE APR 8 2008 .SYNOPSIS... 07Z WATER VAPOR AND H4 RUC ANALYSIS STILL SHOWING AN ACTIVE NORTHERN STREAM ACROSS THE NORTHERN CONUS AND SOUTHERN CANADA. MOST IMPRESSIVE FEATURE TAKES THE FORM OF A CLOSED LOW/POTENT SHORTWAVE FEATURES SPINNING AND MOVING NORTHEAST FROM THE GREAT LAKES INTO SOUTHERN ONTARIO/QUEBEC. FURTHER UPSTREAM WE SEE MORE LONGWAVE TROUGHING ACROSS THE INTERMOUNTAIN WEST/NORTHERN PLAINS. RIDGING IS THEN FOUND FURTHER UPSTREAM COMING ASHORE FROM NORTHERN CALIFORNIA TO BRITISH COLUMBIA. FURTHER SOUTH THE FLOW IS MORE ZONAL IN NATURE FROM NORTHERN MEXICO EASTWARD ALONG THE NORTHERN GULF COAST. WEAK SOUTHERN STREAM DISTURBANCE IS MOVING EAST THROUGH THE SOUTHEASTERN GULF OF MEXICO WITH ALL ITS ASSOCIATED SHOWERS/TSTORMS REMAINING WELL TO OUR SOUTH. AT THE SURFACE...HIGH PRESSURE HAS WEDGED DOWN TO THE EAST OF THE APPALACHIANS FROM THE MID-ATLANTIC STATES TO THE NORTHEAST GULF OF MEXICO. BACK-DOOR COLD FRONT ALONG THE LEADING EDGE OF THE WEDGE RUNNING OUT OF GAS IN ITS WESTERN AND SOUTHERN PROGRESSION. THE BOUNDARY IS NOW LYING FROM NEAR HUNTSVILLE AL SOUTHWARD TO JUST EAST OF BIRMINGHAM AND MONTGOMERY...THEN SOUTHEAST TO NEAR PANAMA CITY BEACH AND OFFSHORE INTO THE NORTHEAST GULF OF MEXICO. THE BOUNDARY THEN TURNS EAST AND RUNS ACROSS THE CENTRAL FLORIDA PENINSULA FROM NEAR OR JUST SOUTH OF TAMPA TO MELBOURNE. BEHIND THE BOUNDARY...AREAS OF LOWER STRATUS CONTINUE TO EXPAND SOUTH AND WEST. CIGS ARE GENERALLY IN THE MVFR RANGE WITH BASES FROM AROUND 1500-2500KFT. TEMPERATURES REGION-WIDE EARLY THIS MORNING FROM THE UPPER 50S TO MIDDLE 60S. && .SHORT TERM (TODAY THROUGH THURSDAY NIGHT)... SURFACE WEDGE OF HIGH PRESSURE WILL REMAIN IN CONTROL OF THE AREA THROUGH TUESDAY NIGHT. ZONAL FLOW CURRENTLY OVER THE NORTHEAST GULF COAST IS FORECAST TO GIVE WAY TO HEIGHT RISES PER 00Z GFS/NAM AS THE FLOW RIDGES UP ALONG THE SOUTHEAST COAST. THIS RIDGING THROUGH A LARGE PORTION OF THE COLUMN SHOULD ENSURE A DRY FORECAST THROUGH AT LEAST TUESDAY NIGHT. MAIN FORECAST CONCERN THROUGH TUESDAY NIGHT WILL BE THE CLOUD AND TEMPERATURE FORECAST. THE AREAS OF LOWER STRATUS ACROSS THE SOUTHEAST ARE COMMON WITH THESE WEDGE HIGH SCENARIOS...HOWEVER THE EXTENT OF CLOUD COVER OVER A LONG PERIOD AND THE EXTENT TO WHICH THE STRATUS MIXES OUT IN ANY ONE LOCATIONS DURING THE DAY CAN BE VERY DIFFICULT TO FORECAST. WILL USE A CONSERVATIVE FORECAST APPROACH AND NOT GO TOO COOL OR TOO WARM IN ANY ONE SPOT. THE FACT THAT THE STRATUS HAS RETAINED A RATHER BROKEN APPEARANCE INTO THE EARLY MORNING HOURS SUGGESTS THAT AT LEAST SOME BREAKS IN THE OVERCAST WILL DEVELOP DURING THE DAY AND ALLOW TEMPS TO WARM. HOWEVER...AS MENTIONED ABOVE...CONFIDENCE CAN NEVER BE THAT HIGH IN THESE SITUATIONS. THE CONSERVATIVE APPROACH GIVES A HIGH TEMPERATURE GRID IN THE MIDDLE AND UPPER 70S. A FEW SPOTS...ESPECIALLY ACROSS THE SOUTH THAT SEE ENOUGH SUN DURING THE AFTERNOON WILL HAVE THE POTENTIAL TO REACH THE 80 DEGREE MARK. WILL LIKELY SEE ONE MORE NIGHT WITH THE FORMATION AND EXPANSION OF AREAS OF LOWER STRATUS TUESDAY NIGHT. REALLY SHOULD BE LITTLE DIFFERENCE BETWEEN EARLY THIS MORNING AND TONIGHT IN TERMS OF CLOUD COVER AND TEMPS. LOWS EXPECTED TO DROP DOWN INTO THE MIDDLE 50S TO NEAR 60 IN THE EAST AND UPPER 50S TO LOWER 60S IN THE WEST. MID-LEVEL SHORTWAVE ENERGY AND AN ASSOCIATED SURFACE FRONT WILL CROSS THE MIDDLE MISSISSIPPI VALLEY INTO THE OHIO/TENNESSEE VALLEYS TUESDAY NIGHT. THIS WILL ACT TO BRIEFLY BREAK DOWN THE MID/UPPER LEVEL RIDGE ACROSS THE SOUTHEAST FOR WEDNESDAY AND NUDGE THE SURFACE HIGH OFF THE SOUTHEAST COAST. WITH THE SURFACE RIDGE PUSHING EAST...FLOW WILL COME AROUND MORE TO THE EAST AND SOUTHEAST THROUGH THE DAY. THE FRONT WELL TO OUR NORTH OVER THE TENNESSEE VALLEY IS PROGGED BY BOTH THE NAM/GFS TO STALL ON WEDNESDAY AND THEN MOVE BACK NORTH AS A WARM FRONT WEDNESDAY NIGHT IN RESPONSE TO A NEW AND MORE POTENT SYSTEM DEVELOPING ACROSS THE CENTRAL AND SOUTHERN PLAINS. THE FORECAST DURING THE WEDNESDAY/WEDNESDAY NIGHT TIME FRAME WAS HEAVILY BASED ON THE NAM/SREF SOLUTIONS. GFS HAS A SIGNIFICANT CONVECTIVE "BLOWUP" IN THE SOUTHEAST GOMEX TUESDAY AFTERNOON/EVENING. THE RESIDUAL EFFECT FROM THIS CONVECTIVE EVENT PUSH NORTH AND RESULT IN SIGNIFICANTLY HIGHER CLOUD COVER AND SHOWER CHANCES OVER THE SOUTHERN FORECAST AREA WEDNESDAY AND WEDNESDAY NIGHT. WITH LITTLE SUPPORT FROM ANY OTHER GUIDANCE PACKAGE FOR THE GFS FIELDS HAVE DECIDED TO BASE THE FORECAST ON A DRIER AND CLEARER FORECAST. A BIT HIGHER MOISTURE COMBINED WITH SOME SEA-BREEZE CONVERGENCE MAY STILL RESULT IN AN ISOLATED SHOWER/TSTORM ACROSS THE FL PANHANDLE WEDNESDAY AFTERNOON...BUT SHOULD BE FEW AND FAR BETWEEN. SIGNIFICANT HEIGHT FALLS ACROSS THE PLAINS WEDNESDAY NIGHT INTO THURSDAY ASSOCIATED WITH A POTENT UPPER LEVEL SYSTEM WILL FORCE THE RIDGE TO RE-AMPLIFY OVER THE SOUTHEASTERN STATES. THE RESULT SHOULD BE A WARM AND MOIST DAY AS SOUTHEAST FLOW BEGINS TO INCREASE BETWEEN THE HIGH OFF TO OUR EAST AND THE DEVELOPING SYSTEM OVER THE PLAINS. HIGH TEMPERATURES SHOULD REACH THE LOWER 80S AWAY FROM THE IMMEDIATE COAST AND THERE WILL ONCE AGAIN BE A SLIGHT RISK OF AN AFTERNOON SHOWER OR TSTORM OVER SOUTHERN AND WESTERN PORTIONS FOR THE AREA. COLD FRONT ASSOCIATED WITH THE PLAINS LOW PUSHES SLOWLY EAST INTO THE MIDDLE/LOWER MISSISSIPPI VALLEY THURSDAY NIGHT. INCREASING SOUTHERLY FLOW AHEAD OF THE FRONT WILL RESULT IN WELL ABOVE NORMAL LOW TEMPERATURES. && .LONG TERM (FRIDAY THROUGH TUESDAY)... MAJOR SHIFT IN THE LONGWAVE PATTERN THIS UPCOMING WEEKEND. DIGGING SHORTWAVE FINALLY BREAKS DOWN RIDGE BEGINNING FRIDAY AHEAD OF HIGHLY AMPLIFIED TROUGH WHICH SETS UP OVER THE EAST COAST ON SUNDAY. DEEPENING H5 LOW OVER NRN GREAT LAKES 12Z SAT DROPS TO NRN MID-ATLC BY 18Z SUN. DIGGING LOW COMBINED WITH SHORTWAVE WILL HELP TO DEFINE SURFACE LOW AND DRIVE NEXT COLD FRONT SEWD. AT THE SURFACE...WEAK HIGH PRESSURE OVER THE AREA THROUGH EARLY FRIDAY. MODELS IN BETTER AGREEMENT IN TIMING OF LOW/FRONT THAN PREV RUN BUT GFS STILL THE OUTLIER AND FASTER THAN ECMWF/CANADIAN. NORTHEAST TRACK OF THE LOW TOWARD THE GREAT LAKES SHOULD RETARD THE GFS`S FAST ARRIVAL OF THE FRONTAL PASSAGE FRI NIGHT/EARLY SATURDAY. THUS LEANING TOWARDS SLOWER SOLUTION. THIS SHOWS LOW IN SRN PLAINS 00Z FRI WITH COLD FRONT EXTENDING SWD. LOW LIFTS RAPIDLY N/NE TO SRN GREAT LAKES BY 12Z FRI...FRONT THRU WRN TENN-ERN ARK...ERN MOST TX. BY 12Z SAT...LOW OVER NRN GREAT LAKES WITH FRONT APPROACHING CWA AND THEN MOVING ACROSS DURING SAT DAY. ALL GUIDANCE SHOWS THAT LIFT WILL WEAKEN CONSIDERABLY BY TIME FRONT ARRIVES WITH HI SCT CONVECTION BEGINNING FRI EVE MAINLY NW THIRD OF CWA SPREADING TO WRN HALF OF CWA FRI NIGHT AND ACROSS ERN CWA ON SAT ENDING SAT EVENING EAST. WITH SLOWER SOLUTION FAVORED HAVE FOCUSED SHOWERS AND THUNDERSTORMS ON SAT. IN WAKE OF FRONT...ANOTHER DRY PERIOD AS HIGH PRESSURE BUILDS IN FROM THE NORTH OVER WEEKEND WITH MODERATE TO STRONG COLD AIR ADVECTION AND DRIER COOLER CONDITIONS ARE EXPECTED SUNDAY INTO THE EARLY WORK WEEK. TEMPS SHOULD CONTINUE ABOVE CLIMO ON FRI WITH INLAND HIGHS LIKELY REACHING THE LOWER TO MID 80S...THEN DROP TO MID-UPPER 70S SAT WITH FRONT AND MID 60S SE ALA TO LOW 70S SE BIG BEND ON SUN AND MON IN WAKE OF FRONT BEFORE INCHING UP TO LOW 70S ON TUES. INLAND LOW TEMPS WILL REMAIN ABOVE CLIMO FRI AND SAT MORNING...LOW-MID 60S THEN IN WAKE OF FRONT DROP AROUND 50 SUN AND AROUND 40 MON BEFORE INCHING UP TO MID 40S TUES MORNING. && .AVIATION... MAIN OVERNIGHT AND EARLY MORNING FORECAST CONCERN REMAINS LOW CEILINGS...ALTHO VSBYS WILL NOT DROP AS LOW AS PREVIOUS NIGHT... CIGS WILL GET DOWN INTO THE LIFR RANGE. VFR VSBYS EXPECTED BY 14Z BUT MVFR CIGS TO LAST UNTIL 16Z-17Z. THEN...VFR CONDS UNTIL AROUND 06Z WED WHEN MVFR CIGS BEGIN TO DEVELOP BUT VSBYS WILL REMAIN VFR. && .MARINE... FORECAST WATERS RESIDE ON THE SOUTHERN PERIPHERY OF HIGH PRESSURE EXTENDING FROM THE MIDDLE ATLANTIC STATES TO THE NORTHEAST GULF OF MEXICO. CAUTIONARY CONDITIONS ARE LIKELY THIS MORNING ACROSS A LARGE PORTION OF THE MARINE AREA BEFORE DROPPING A BIT FOR THE AFTERNOON. YET ANOTHER EASTERLY SURGE TO NEAR CAUTIONARY LEVELS IS EXPECTED TUESDAY NIGHT INTO WEDNESDAY MORNING. AS THE SURFACE HIGH SLIDES EAST OFF THE SOUTHEAST COAST WEDNESDAY INTO THURSDAY LOOK FOR WINDS TO COME AROUND TO THE SOUTHEAST AND THEN EVENTUALLY TO THE SOUTH BY THE END OF THE WEEK WITH THE APPROACH OF THE NEXT COLD FRONT ON SATURDAY. && .FIRE WEATHER... LACK OF SIGNIFICANT DRY AIR IN THE LOWER LEVELS WILL KEEP RH VALUES ABOVE CRITICAL LEVELS THROUGH THE MIDDLE OF THE WORK WEEK. INCREASING SOUTHERLY FLOW THURSDAY INTO FRIDAY WILL ONLY INCREASE THE LOWER LEVEL MOISTURE. CRITICAL FIRE WX CONDITIONS ARE NOT ANTICIPATED THROUGH AT LEAST FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 79 58 80 61 82 / 0 0 10 10 20 PANAMA CITY 78 61 78 64 79 / 0 0 20 10 20 DOTHAN 76 57 79 61 81 / 0 0 10 10 20 ALBANY 76 55 80 58 80 / 0 0 10 10 10 VALDOSTA 76 55 79 58 81 / 0 0 10 10 10 CROSS CITY 80 57 80 60 83 / 0 0 10 10 20 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ PUBLIC/MARINE...MROCZKA AVIATION/LONG TERM...BLOCK fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 1155 PM CDT MON APR 7 2008 .UPDATED AVIATION DISCUSSION. .DISCUSSION... STILL SOME UNCERTAINTY FOR PTYPE THROUGH ALL OF TUESDAY. HAVE ADDED CHANCE SNOW IN THE MORNING ALONG WITH THE EXPECTED RAIN. LOTS OF DRY AIR AT H850 THIS EVENING AND NEW NAM...THOUGH NAM ISNT INITIALIZING THE EXTENT OF QPF PRESENTLY...IT CONTINUES TO POINT TOWARD A FASTER RAIN/SNOW CHANGEOVER FOR THE LATE MORNING AND AFTERNOON HOURS. SFC TEMPS MAY BE WARM ENOUGH TO KEEP A MIX GOING...ONCE IT BEGINS... THOUGH IF SHOWERS ARE HEAVY ENOUGH...WE COULD HAVE A SITUATION SIMILAR TO LAST THURSDAY WITH AN AREA OF WET SNOW SURROUNDED BY AREAS OF RAINFALL. FOR THE MOMENT THE SNOW OVER NE HAS LESSENED. WILL BE LOOKING AT LATEST GFS AND RUC CLOSELY. EARLIER...UPDATED ZONES FOR INCREASED AREAL COVERAGE OF SHOWERS SOUTH. ALREADY GETTING MEASURABLE ALONG THE BORDER COUNTIES. LOTS OF VIRGA OUTSIDE ATTM WITH DRY LAYER BEGINNING TO FILL IN. SNOW CONTINUES OVER SOUTH CENTRAL NE AND WILL BE LOOKING CLOSELY AT UPPER AIR/NEW MODEL OUTPUT OVER THE NEXT SEVERAL HOURS FOR ANY SIGN OF PTYPE ISSUES TUES./REV .PREVIOUS DISCUSSION... AN ACTIVE WEATHER PATTERN REMAINS IN STORE FOR CENTRAL IOWA THROUGH THE FORECAST PERIOD. WATER VAPOR SHOWING AN UPPER LEVEL SHORTWAVE CROSSING THE ROCKIES AND TRYING TO FORM WHAT LOOKS LIKE A BAROCLINIC LEAF ON THE LEE SIDE. AT THE SURFACE...LOW PRESSURE ACROSS TX/NEW MEXICO WILL LIFT NORTHEAST OVERNIGHT. A WARM FRONT EXTENDS FROM THE LOW INTO OK AND SRN MO. OVERRUNNING SETTING UP AND PRODUCING SCATTERED SHOWERS MAINLY OVER KS AND NEB. AS THE SHORTWAVE MOVES IN IT SHOULD ENHANCE ACTIVITY ALONG AND NORTH OF THE FRONT. FROM THE LOOKS OF THINGS THE BETTER MOISTURE WILL STAY TO THE SOUTH OF IOWA AND THUS ONLY MEAGER CAPE VALUES TONIGHT AND WEDNESDAY. THERE SHOULD BE ENOUGH FOR SOME ISOLATED THUNDER NEAR THE BOUNDARY. THIS SHOULD COME CLOSE ENOUGH TO IOWA TO GIVE A SMALL PORTION OF SE IA A SHOT AT SOME THUNDER. SHEAR IS DECENT WITH THIS SYSTEM BUT WITH VERY LOW CAPES AND THE AREA NOT GETTING INTO THE WARM SECTOR AT ALL I WOULD EXPECT ELEVATED STORMS THOUGH SEVERE POTENTIAL NOT LOOKING LIKE MUCH AT THIS POINT. QPF HOWEVER LOOKS PRETTY GOOD AS A BETTER MOISTURE TAP OCCURS BY 18Z TUES. SYSTEM LIFTS OUT BY LATE TUESDAY. THERE WILL THEN BE A BRIEF RESPITE ON WEDNESDAY AS HIGH PRESSURE MOVES IN THEN DEPARTS BY MID EVENING. THE NEXT SYSTEM THEN BEGINS TO LIFT OUT OF THE SOUTHERN PLAINS FOR WEDNESDAY NIGHT AND THURSDAY. MODELS CONTINUE TO DISAGREE MAINLY ON TIMING BUT GENERAL TRENDS ARE TO LIFT THE LOW OUT OF THE SOUTHERN PLAINS AND ACROSS IOWA BY LATE THURSDAY NIGHT. THERE IS ALSO SOME QUESTION AS TO HOW MUCH COLD AIR THIS SYSTEM WILL TAP INTO. THE GFS IS SLOWER WITH THIS SYSTEM AND THUS ALLOWS A LITTLE MORE COLD AIR INTO THE NW. THE EURO HAS A BIGGER GULF TAP AND PUTS THE WARM SECTOR INTO MORE INTO EASTERN IOWA THEN AS THE SYSTEM MOVES NE COLDER AIR PUSHES IN LATER THURSDAY NIGHT AND LINGERS THROUGH FRIDAY. GIVEN THE STRENGTH OF THE UPPER LOW I LIKE THE SLOWER GFS BUT THINK THAT THE WARM SECTOR WILL MAKE ITS WAY INTO SOUTHEAST IOWA. IN SHORT I WENT WITH A BLEND OF THE GFS/EURO. THIS COULD BE A POTENTIAL SNOW PRODUCER FOR LOCATIONS NORTH OF IOWA BUT WILL MONITOR FOR THE POTENTIAL TO SLIP INTO NORTHERN IOWA THURSDAY NIGHT. && .AVIATION...08/06Z COMPLICATED FORECAST CONTINUES FOR THIS TAF PERIOD. MODELS HAVE TO INITIALIZED THE 00Z RUN BETTER WITH THE GFS DOING BETTER AS FOR QPF PLACEMENT AND INTENSITY. GFS/NAM CONTINUE DIFFERENT BUT SOME COMMONALITIES IN PTYPE NOW SHOWING UP. FOR THE LATE MORNING TO AFTERNOON HOURS...THERE WILL BE A CHANCE OF R/S AND POSSIBLE A QUICK CHANGEOVER TO -SN/SN FROM EAST OF KDSM TO NEAR KALO FOR A PERIOD OF 2 TO 3 HOURS. FOR LATER IN THE MORNING AND AFT HOURS...CIGS WILL DROP INTO MVFR CAT WITH NORTHERN SITES DOWN TO IFR PRIOR TO CIGS LIFTING. MODELS NOW INDICATE THE SYSTEM PULLING AWAY BY 03 TO 06Z SO MAY NEED TO LIFG CIGS FASTER IN NEXT PACKAGE. POTENTIAL FOR LOWER CIGS TUES 15Z-20Z IF THE PRECIP CHANGES OVER TO SNOW. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...MS APR 08/REV AVIATION...REV LONG TERM...FAB ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 349 AM CDT TUE APR 8 2008 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT CURRENT WATER VAPOR IMAGERY EARLY THIS MORNING REVEALS A WEAK SHORTWAVE TROUGH MOVING OVER THE AREA. THIS DISTURBANCE IS CONTINUING TO BRING LIGHT RAIN/SNOW ACROSS A SMALL PORTION OF CENTRAL SOUTH DAKOTA...WITH A DECREASE IN AREAL COVERAGE OVER THE PAST COUPLE HOURS. PHP REPORTED -RA AND 36 DEGREES THE PAST HOUR BUT PIR STILL HAS A CEILING OF 10000 FT. RADAR ECHOES WOULD SUGGEST WESTERN PARTS OF JONES/STANLEY COUNTIES ARE SEEING PRECIPITATION. LOOKING UPSTREAM THERE IS ANOTHER WEAK WAVE WHICH WILL MOVE EAST/NORTHEAST ACROSS THE AREA LATER THIS MORNING. IN FACT...PRECIPITATION IS INCREASING ACROSS NORTHERN NEBRASKA AND IS BEGINNING TO MOVE NORTHWARD INTO SOUTH DAKOTA. THE RUC MODEL IS PICKING UP ON THIS AND BRINGS LIGHT QPF INTO THE FAR SOUTHWEST COUNTIES OVER THE NEXT SEVERAL HOURS. 06Z NAM/00Z GFS AND SREF GUIDANCE ALL SUGGESTING A SMALL CHANCE FOR PRECIPITATION IS WARRANTED ACROSS THE FAR WESTERN CWA FOR THE MORNING HOURS AT LEAST. OTHERWISE...MORE CLOUDS WILL BE HAD ACROSS THE FORECAST AREA TODAY AS THE WEAK WAVES SLIDE OVER THE AREA. TEMPERATURES SHOULD STILL BE ABLE TO RISE FAIRLY WELL OVER THE SNOWFIELD...AS WAS THE CASE YESTERDAY...BUT MORE CLOUDS WILL KEEP THEM FROM GOING TOO HIGH. WILL MORE THAN LIKELY SEE TEMPS FAIRLY CLOSE TO MONDAYS HIGHS BUT AREAS THAT WERE HELD BACK ON MONDAY WILL BE ABLE TO REBOUND TODAY AS SNOW COVER IS MUCH LESS. ATTENTION THEN TURNS TO INCREASING PRECIP CHANCES FOR WEDNESDAY AND WEDNESDAY NIGHT AS MOISTURE SURGES NORTHWARD IN ADVANCE OF A STRONG WESTERN CONUS TROUGH. ALL MODELS ARE NOW SUGGESTING PRECIP STARTING EARLIER THAN PREVIOUSLY THOUGHT ACROSS THE WESTERN CWA SO HAVE INSERTED POPS FOR WEDNESDAY AFTERNOON ACROSS THE WEST. HAVE ALSO INCREASED POPS TO LIKELY WEDNESDAY NIGHT ACROSS CENTRAL SOUTH DAKOTA. LOOKS WARM ENOUGH FOR ALL RAIN WEDNESDAY...AND EVEN INTO MUCH OF WEDNESDAY NIGHT. WILL THEREFORE LEAVE A RAIN OR SNOW MENTION FOR WEDNESDAY NIGHT AS TEMPS WILL BE MARGINAL. BUFKIT SOUNDINGS WOULD SUGGEST PIR/MBG STAY RAIN ALL THE WAY INTO THURSDAY. .LONG TERM...12Z THURSDAY THROUGH MONDAY. BIGGEST CHALLENGE IN THE EXTENDED FORECAST REVOLVES AROUND LATE SEASON WINTER STORM MOVING INTO THE AREA THURSDAY-SATURDAY TIME FRAME. MODELS ARE SLOWLY CONVERGING ON A SIMILAR SOLN FOR THE THURSDAY THROUGH SATURDAY TIME FRAME...WITH THE GFS SLOWLY BACKING TO THE WEST...COMING IN LINE MUCH CLOSER TO PREVIOUS EC RUNS. 12Z THURSDAY STARTS OFF WITH LONG WAVE TROF DIGGING ACROSS 4 CORNERS AREA. BY 00Z FRIDAY EC ADVERTISES A COUPLED JET STRUCTURE FOR THE CWA...WHICH WILL ONLY ENHANCE LIFT FOR US. THE GFS ISN`T AS STRONG WITH THE COUPLED JET FEATURE...BUT SHOWS A LOT OF UPPER DIVERGENCE ACROSS THE FAR ERN CWA BY 12Z FRIDAY. THE EC HAS BEEN RATHER CONSISTENT WITH AMOUNT OF 7H/85H THETA-E FORCING THAT TAKES PLACE FROM 00Z FRIDAY THROUGH 00Z SATURDAY. SO FAR THIS SPRING TROWAL INDUCED SNOWFALL HAS BEEN RATHER EFFECTIVE AT PRODUCING SNOW...AND GIVEN THAT BUFKIT SHOWS STRONG OMEGA VALUES LIFTING THROUGH SNOW PRODUCTION ZONE...EXPECT THIS TO BE MUCH THE SAME. BUFKIT SNOWFALL TOTALS ARE RATHER IMPRESSIVE...WITH MEASUREMENTS IN FEET RATHER THAN INCHES. WITH 5H CLOSED LOW LIFTING NEARLY DUE NORTH OVERNIGHT THURSDAY...PROLONGED PERIOD OF SNOW IS EXPECTED. ESPECIALLY WHEN THE GFS 7H-3H Q-VECTOR ANALYS SHOWS WAA FORCING CONTINUING ACROSS NERN CWA THROUGH NEARLY 12Z SATURDAY ASSOCIATED WITH CONTINUED TROWAL FEATURE. THERE IS SOME CONCERN ABOUT PCPN TYPE TO BEGIN THE EXTENDED ON THURSDAY. THE GFS 85H-7H THICKNESS VALUES SUGGEST THAT THE SW PART OF THE CWA MAY SEE A RAIN/SNOW MIX...AND 85H/925H TEMPS DO SUPPORT THAT. BUT GIVEN EVAPORATIVE COOLING THAT IS EXPECTED HEADING INTO THE AFTERNOON...COUPLED WITH THE MODELS SHOWING 85H AND 925MB TEMPS COOLING...EXPECT A TURN OVER TO SNOW FOR ALL THE CWA DURING THE AFTN. AS CLOSED/STACKED SYSTEM SLOWLY EXITS EAST ON SATURDAY...HAVE PCPN ENDING ALSO WEST TO EAST FOR THAT TIME PERIOD. GIVEN THAT GFS IS SHOWING THAT 925MB GEOSTROPHIC WINDS ARE 40-50 KTS BY 12Z FRIDAY...HAVE NO DOUBT THAT HEADLINES WILL BE NEEDED FOR THE THURSDAY AFTN/FRIDAY EVENING TIME PERIOD. TEMP WISE...WITH EXPECTED ABUNDANCE OF CLOUDS AND PCPN FOR THURSDAY-SATURDAY TIME FRAME...HAVE KNOCKED AT LEAST 5 DEGREES OFF OF INHERITED FORECAST HIGHS. DON`T SEE MUCH RECOVERY FROM OVERNIGHT LOWS...NOR MUCH DIURNAL TREND ONCE PCPN BEGINS. FORECASTED HIGHS MAY NEED TO BE TRIMMED BACK JUST A BIT FURTHER...BUT CAN FINE TUNE THAT AS EVENT APPROACHES. && .AVIATION... WEAK UPPER LEVEL SYSTEM IS SKIRTING ACROSS NEB ATTM...WITH MID/HI LEVEL CLOUDINESS STREAMING ACROSS TERMINAL SITES. AREA OF -RA/-SN LIFTING NORTH OUT OF NEBRASKA MAY IMPACT KPIR TERMINAL AFT 11Z...WITH MVFR CIGS POSSIBLE. THIS PCPN SHOULD END BY 16Z WITH VFR CIGS MOVING BACK INTO THE KPIR TERMINAL BY 18Z. LOOK FOR VFR CONDS FOR THE KMBG/KABR/KATY TERMINALS THROUGH 00Z WEDNESDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...TMT LONG TERM...HINTZ AVIATION...HINTZ WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 1035 AM EDT TUE APR 8 2008 .SYNOPSIS... A WEDGE OF HIGH PRES WILL REMAIN IN PLACE ACROSS THE AREA THROUGH TONIGHT. HIGH PRES WILL WEAKEN ON WED BEFORE SHIFTING OFF THE COAST LATE WEEK. A COLD FRONT WILL MOVE THROUGH THE SE UNITED STATES THIS WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MAIN FORECAST ISSUE FOR TODAY WILL INVOLVE CLOUD COVER AND MAX TEMPERATURES...AS THE PERSISTENT SURFACE WEDGE PATTERN REMAINS IN CONTROL EAST OF THE APPALACHIANS. LATEST SATELLITE IMAGERY DEPICTS A HOLE IN THE THICK LOW CLOUDS OVER EASTERN GEORGIA. THIS AREA OF CLEARING HAS LINGERED FOR THE PAST SEVERAL HOURS...BUT HAS NOT EXPANDED DURING THE SAME TIME PERIOD. THERE ALSO APPEARS TO BE SOME WEAKENING IN THE CEILINGS OVER NORTH CAROLINA AND NORTHEASTERN SOUTH CAROLINA THIS HOUR. THE RUC13 SEEMS TO CAPTURE THE CLOUD PATTERN FAIRLY WELL...AND THE MODEL SHORT TERM FORECAST SUGGESTS A MORE SIGNIFICANT SCATTERING OF THE CEILINGS WILL OCCUR THIS AFTERNOON OVER AREAS TO THE SOUTH AND ALONG THE COAST WITH THE SEABREEZE. CLOUDS MAY BE MORE PERSISTENT FOR LOCATIONS IN THE NORTHWESTERN FORECAST AREA CLOSER TO THE AXIS OF THE SURFACE WEDGE...SUCH AS A LINE ALONG AND WEST OF JENKINS COUNTY INTO WESTERN BERKELEY COUNTY. HIGH TEMPERATURES THIS AFTERNOON WILL BE GREATLY DEPENDENT ON THE EXTENT OF CLEARING THAT OCCURS. CURRENT FORECAST TEMPERATURES ARE RUNNING A FEW DEGREES BELOW OBSERVATIONS...SO WILL MAKE SOME MINOR TWEAKS TO THE HOURLY TREND. WILL MAINTAIN THE ONGOING FORECAST HIGH TEMPERATURES...AS SCATTERING CLOUD COVER MAY INDEED ALLOW MAX TEMPERATURES TO RISE TO AROUND 68 DEGREES NORTHERN COUNTIES TO THE LOWER 70S SOUTHERN ZONES. SKY COVER TREND IS ALSO WELL-HANDLED IN THE ONGOING FORECAST...SO NO MAJOR CHANGES WILL BE NECESSARY OTHERWISE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... MET AND MAV GUIDANCE IN SOME DISAGREEMENT OVER THE POTENTIAL FOR LOW CEILINGS TO DEVELOP TONIGHT. HAVE GONE WITH A PARTLY CLOUDY FORECAST OVERALL AND LOWS IN THE UPPER 40S TO MID 50S...WITH COOLEST READINGS INLAND FROM CHARLESTON AND BEAUFORT AND WARMEST ALONG THE ENTIRE IMMEDIATE COAST. LIGHTER WINDS ACROSS ALL AREAS TONIGHT MAY ALLOW FOR SHALLOW FOG DEVELOPMENT LATE...ESPECIALLY ACROSS OUR INLAND LOCATIONS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... MEDIUM RANGE GUIDANCE IS IN EXCELLENT AGREEMENT THROUGHOUT THE EXTENDED PERIOD THIS MORNING. HIGH PRESSURE IS EXPECTED TO REMAIN THE DOMINANT WEATHER FEATURE WEDNESDAY THROUGH FRIDAY...RESULTING IN RAIN FREE WEATHER ACROSS THE AREA. A COLD FRONT WILL MOVE THROUGH THE REGION LATE SATURDAY...AND WILL CARRY CHANCE POPS SATURDAY...AND SLIGHT CHANCE POPS SATURDAY NIGHT FOR PORTIONS OF THE AREA...TO ACCOUNT FOR THIS. HIGH PRESSURE IS THEN EXPECTED TO BUILD IN BEHIND THE DEPARTING COLD FRONT FOR SUNDAY AND MONDAY RESULTING IN RAIN FREE WEATHER ACROSS THE AREA. TEMPERATURES WILL BE NEAR TO SEVERAL DEGREES ABOVE CLIMATOLOGY WEDNESDAY THROUGH SATURDAY. TEMPERATURES WILL DROP TO BELOW NORMAL LEVELS SUNDAY AND MONDAY BEHIND THE COLD FRONT. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... MVFR CEILINGS AT BOTH KSAV AND KCHS THIS MORNING. CIGS SHOULD LIFT ABOVE 3 KFT THIS AFTERNOON...OR POSSIBLY SCATTER OUT COMPLETELY IN THE WAKE OF THE SEA BREEZE PASSAGE THIS AFTERNOON. N TO NE WINDS MOSTLY BLO 15 KT TODAY...BECOMING MORE EASTERLY LATE DAY. NOT ENOUGH CONFIDENCE AT THIS TIME TO INDICATE IFR OR LOWER CIGS AT EITHER TAF LATE TONIGHT...ALTHOUGH A POTENTIAL FOR THIS DEVELOPMENT DOES EXIST WITHIN DIMINISHING WINDS AND TRAPPED LOW LEVEL MOISTURE. EXTENDED AVIATION OUTLOOK...IFR CIGS ARE POSSIBLE EARLY WED. MVFR OR LOWER VSBYS POSSIBLE IN FOG THU AND FRI MORNINGS. MVFR CONDITIONS POSSIBLE IN SHOWERS AND TSTMS SAT. && .MARINE... TIGHTENED PRESSURE GRADIENT REMAINS OVER THE COASTAL WATERS THIS MORNING...AS HIGH PRESSURE CONTINUES TO RIDGE INLAND AND LOW PRESSURE TO THE SOUTH SLIPS FURTHER INTO THE ATLANTIC. ONGOING SMALL CRAFT ADVISORIES FOR ALL ZONES EXCEPT CHARLESTON HARBOR CONTINUE TO LOOK ON TRACK. ADVISORY WILL BE UPHELD IN THE NEARSHORE SOUTH CAROLINA WATERS THROUGH THE EARLY AFTERNOON JUST DUE TO SEAS FROM 4 TO 6 FEET SUBSIDING DURING THE NEXT SEVERAL HOURS. THE NEARSHORE GEORGIA COASTAL WATERS WILL BE CLOSER TO THE LOW SYSTEM CREATING THE PINCHED GRADIENT...THUS SMALL CRAFT ADVISORY IS BEING MET CURRENTLY THROUGH WINDS AND SEAS AND WILL BE MAINTAINED THROUGH THE EVENING BY SEAS ONLY. PERSISTENT NORTHEAST FETCH DURING THE PAST FEW DAYS WILL MAINTAIN ELEVATED SEAS IN THE OFFSHORE GEORGIA WATERS THROUGH THE SHORT TERM. MODELS CONTINUE TO INDICATE A GENERAL GRADIENT RELAXATION TREND TONIGHT. WINDS WILL DIMINISH QUICKER OVER SOUTH CAROLINA WATERS...WHILE BEING A BIT SLOWER TO DECREASE OVER BOTH OF THE SOUTHEAST GEORGIA ZONES. HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE WEDNESDAY THROUGH FRIDAY. A COLD FRONT WILL APPROACH THE WATERS FROM THE WEST ON SATURDAY. FAVORABLE NORTHEAST FETCH WILL RESULT IN SMALL CRAFT CONDITIONS DUE TO ELEVATED SEAS LINGERING ACROSS THE OUTER GEORGIA WATERS THROUGH AROUND NOON ON THURSDAY. OTHERWISE WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT THRESHOLDS WEDNESDAY THROUGH SATURDAY. && .TIDES/COASTAL FLOODING... TIDE LEVELS REACHED SHALLOW COASTAL FLOODING CRITERIA AT DOWNTOWN CHARLESTON AND FORT PULASKI GEORGIA LAST EVENING AND MAY DO SO AGAIN AROUND HIGH TIDE THIS EVENING. MINOR COASTAL FLOODING RISK MAY NECESSITATE A RE-ISSUANCE OF COASTAL FLOOD ADVISORIES LATER TODAY FOR HIGH TIDE THIS EVENING. RIP CURRENTS...A MODERATE RISK OF RIP CURRENTS IS FORECAST TODAY. A LINGERING NE SWELL COMPONENT MAY ELEVATE THE RISK SOMEWHAT ON WED. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR AMZ350- 352. SMALL CRAFT ADVISORY UNTIL 12 PM EDT THURSDAY FOR AMZ374. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR AMZ354. && $$ ga AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1128 AM CDT TUE APR 8 2008 .UPDATE... MADE A FEW CHANGES TO SKY COVER THIS MORNING AS SOME CLEARING TAKING PLACE ACROSS THE EASTERN CWA. ALSO RAISED TEMPERATURES A BIT IN THE SOUTHEASTERN CWA DUE TO MORE WARMING TAKING PLACE UNDER MORE SUN. NEW AVIATION DISCUSSION BELOW. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT CURRENT WATER VAPOR IMAGERY EARLY THIS MORNING REVEALS A WEAK SHORTWAVE TROUGH MOVING OVER THE AREA. THIS DISTURBANCE IS CONTINUING TO BRING LIGHT RAIN/SNOW ACROSS A SMALL PORTION OF CENTRAL SOUTH DAKOTA...WITH A DECREASE IN AREAL COVERAGE OVER THE PAST COUPLE HOURS. PHP REPORTED -RA AND 36 DEGREES THE PAST HOUR BUT PIR STILL HAS A CEILING OF 10000 FT. RADAR ECHOES WOULD SUGGEST WESTERN PARTS OF JONES/STANLEY COUNTIES ARE SEEING PRECIPITATION. LOOKING UPSTREAM THERE IS ANOTHER WEAK WAVE WHICH WILL MOVE EAST/NORTHEAST ACROSS THE AREA LATER THIS MORNING. IN FACT...PRECIPITATION IS INCREASING ACROSS NORTHERN NEBRASKA AND IS BEGINNING TO MOVE NORTHWARD INTO SOUTH DAKOTA. THE RUC MODEL IS PICKING UP ON THIS AND BRINGS LIGHT QPF INTO THE FAR SOUTHWEST COUNTIES OVER THE NEXT SEVERAL HOURS. 06Z NAM/00Z GFS AND SREF GUIDANCE ALL SUGGESTING A SMALL CHANCE FOR PRECIPITATION IS WARRANTED ACROSS THE FAR WESTERN CWA FOR THE MORNING HOURS AT LEAST. OTHERWISE...MORE CLOUDS WILL BE HAD ACROSS THE FORECAST AREA TODAY AS THE WEAK WAVES SLIDE OVER THE AREA. TEMPERATURES SHOULD STILL BE ABLE TO RISE FAIRLY WELL OVER THE SNOWFIELD...AS WAS THE CASE YESTERDAY...BUT MORE CLOUDS WILL KEEP THEM FROM GOING TOO HIGH. WILL MORE THAN LIKELY SEE TEMPS FAIRLY CLOSE TO MONDAYS HIGHS BUT AREAS THAT WERE HELD BACK ON MONDAY WILL BE ABLE TO REBOUND TODAY AS SNOW COVER IS MUCH LESS. ATTENTION THEN TURNS TO INCREASING PRECIP CHANCES FOR WEDNESDAY AND WEDNESDAY NIGHT AS MOISTURE SURGES NORTHWARD IN ADVANCE OF A STRONG WESTERN CONUS TROUGH. ALL MODELS ARE NOW SUGGESTING PRECIP STARTING EARLIER THAN PREVIOUSLY THOUGHT ACROSS THE WESTERN CWA SO HAVE INSERTED POPS FOR WEDNESDAY AFTERNOON ACROSS THE WEST. HAVE ALSO INCREASED POPS TO LIKELY WEDNESDAY NIGHT ACROSS CENTRAL SOUTH DAKOTA. LOOKS WARM ENOUGH FOR ALL RAIN WEDNESDAY...AND EVEN INTO MUCH OF WEDNESDAY NIGHT. WILL THEREFORE LEAVE A RAIN OR SNOW MENTION FOR WEDNESDAY NIGHT AS TEMPS WILL BE MARGINAL. BUFKIT SOUNDINGS WOULD SUGGEST PIR/MBG STAY RAIN ALL THE WAY INTO THURSDAY. .LONG TERM...THURSDAY THROUGH MONDAY BIGGEST CHALLENGE IN THE EXTENDED FORECAST REVOLVES AROUND LATE SEASON WINTER STORM MOVING INTO THE AREA THURSDAY-SATURDAY TIME FRAME. MODELS ARE SLOWLY CONVERGING ON A SIMILAR SOLN FOR THE THURSDAY THROUGH SATURDAY TIME FRAME...WITH THE GFS SLOWLY BACKING TO THE WEST...COMING IN LINE MUCH CLOSER TO PREVIOUS EC RUNS. 12Z THURSDAY STARTS OFF WITH LONG WAVE TROF DIGGING ACROSS 4 CORNERS AREA. BY 00Z FRIDAY EC ADVERTISES A COUPLED JET STRUCTURE FOR THE CWA...WHICH WILL ONLY ENHANCE LIFT FOR US. THE GFS ISN`T AS STRONG WITH THE COUPLED JET FEATURE...BUT SHOWS A LOT OF UPPER DIVERGENCE ACROSS THE FAR ERN CWA BY 12Z FRIDAY. THE EC HAS BEEN RATHER CONSISTENT WITH AMOUNT OF 7H/85H THETA-E FORCING THAT TAKES PLACE FROM 00Z FRIDAY THROUGH 00Z SATURDAY. SO FAR THIS SPRING TROWAL INDUCED SNOWFALL HAS BEEN RATHER EFFECTIVE AT PRODUCING SNOW...AND GIVEN THAT BUFKIT SHOWS STRONG OMEGA VALUES LIFTING THROUGH SNOW PRODUCTION ZONE...EXPECT THIS TO BE MUCH THE SAME. BUFKIT SNOWFALL TOTALS ARE RATHER IMPRESSIVE...WITH MEASUREMENTS IN FEET RATHER THAN INCHES. WITH 5H CLOSED LOW LIFTING NEARLY DUE NORTH OVERNIGHT THURSDAY...PROLONGED PERIOD OF SNOW IS EXPECTED. ESPECIALLY WHEN THE GFS 7H-3H Q-VECTOR ANALYSIS SHOWS WAA FORCING CONTINUING ACROSS NERN CWA THROUGH NEARLY 12Z SATURDAY ASSOCIATED WITH CONTINUED TROWAL FEATURE. THERE IS SOME CONCERN ABOUT PCPN TYPE TO BEGIN THE EXTENDED ON THURSDAY. THE GFS 85H-7H THICKNESS VALUES SUGGEST THAT THE SW PART OF THE CWA MAY SEE A RAIN/SNOW MIX...AND 85H/925H TEMPS DO SUPPORT THAT. BUT GIVEN EVAPORATIVE COOLING THAT IS EXPECTED HEADING INTO THE AFTERNOON...COUPLED WITH THE MODELS SHOWING 85H AND 925M TEMPS COOLING...EXPECT A TURN OVER TO SNOW FOR ALL THE CWA DURING THE AFTN. AS CLOSED/STACKED SYSTEM SLOWLY EXITS EAST ON SATURDAY...HAVE PCPN ENDING ALSO WEST TO EAST FOR THAT TIME PERIOD. GIVEN THAT GFS IS SHOWING THAT 925MB GEOSTROPHIC WINDS ARE 40-50 KTS BY 12Z FRIDAY...HAVE NO DOUBT THAT HEADLINES WILL BE NEEDED FOR THE THURSDAY AFTN/FRIDAY EVENING TIME PERIOD. TEMP WISE...WITH EXPECTED ABUNDANCE OF CLOUDS AND PCPN FOR THURSDAY-SATURDAY TIME FRAME...HAVE KNOCKED AT LEAST 5 DEGREES OFF OF INHERITED FORECAST HIGHS. DON`T SEE MUCH RECOVERY FROM OVERNIGHT LOWS...NOR MUCH DIURNAL TREND ONCE PCPN BEGINS. FORECASTED HIGHS MAY NEED TO BE TRIMMED BACK JUST A BIT FURTHER...BUT CAN FINE TUNE THAT AS EVENT APPROACHES. && .AVIATION... AN AREA OF MID CLOUDS BETWEEN 6K AND 10K FEET WILL REMAIN ALONG THE MISSOURI RIVER AREA THIS AFTERNOON. HIGHER CLOUDS AOA 11K FEET WILL PUSH NORTHWARD ACROSS THE NORTH CENTRAL AND NORTHEASTERN CWA...WHILE THE SOUTH CENTRAL AND SOUTHEASTERN CWA WILL SEE JUST SOME SCATTERED HIGH CLOUDS AOA 15K FEET STREAM ACROSS THE AREA. VSBYS WILL BE UNRESTRICTED. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...PARKIN SHORT TERM...TMT LONG TERM...HINTZ AVIATION...PARKIN WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1024 AM EDT TUE APR 8 2008 .SYNOPSIS... A WEDGE REMAINS ACROSS PARTS OF CENTRAL VIRGINIA...AS TWO AREAS OF LOW PRESSURE TRAVEL THROUGH THE GREAT LAKES AND OFF THE SOUTHEASTERN COAST TONIGHT. A WEAK FRONT ACROSS WEST VIRGINIA WILL PASS NORTH AS A WARM FRONT THURSDAY...BEFORE A COLD FRONT ARRIVES ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A HIGH PRESSURE WEDGE REMAINS ENTRENCHED ACROSS MUCH OF THE AREA WITH ASSOCIATED LOW STRATUS CLOUDS. WHILE THE TREND OF THE LOW LEVEL MOISTURE HAS BEEN FOR IT TO PROGRESSIVELY BECOME MORE SHALLOW...SATELLITE TRENDS THIS MORNING SHOW A SOUTHWESTWARD ADVECTION OF A LITTLE DEEPER MOISTURE INTO THE PIEDMONT. THINK THIS WILL KEEP THE PIEDMONT AREAS CLOUDY LONGER THAN EARLIER FCST- ESPECIALLY THE VA PIEDMONT...SO I WILL RAISE SKY COVER SOME AND LOWER MAX TEMPS. LOOKING AT RNK SOUNDING...THE LOW LEVEL MOISTURE IS SHALLOW ENOUGH THAT HEATING SHOULD STILL MIX OUT THE LOW CLOUDS FOR SOME SUN THIS AFT WEST OF THE BLUE RIDGE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... TONIGHT ONCE THE LOW LEVEL INVERSION RETURNS...LOOK FOR LOW CLOUDS TO REDEVELOP ACROSS MUCH OF THE AREA...ALTHOUGH THE SPEED OF REDEVELOPMENT SHOULD BE A LITTLE SLOWER...ESPECIALLY IN THE WEST. AFTER MIDNIGHT. HAVE AGAIN FOLLOWED MET MOS FOR LOW TEMPERATURES WITH ADJUSTMENTS FOR LOCAL BIASES. WEDNESDAY LOOK FOR INCREASING WARM AIR ADVECTION IN ADVANCE OF AN APPROACHING COLD FRONT TO FINALLY ERODE OUT THE WEDGE...BUT CLOUD COVER SHOULD STILL BE ABUNDANT AS MID AND HIGH LEVEL CLOUDS BEGIN TO INCREASE AHEAD OF THE SYSTEM. SHOWERS AND STORMS WILL START TO MOVE INTO THE WESTERN PARTS OF THE AREA AROUND NOON...AND REMAIN GENERALLY CONFINED TO AREAS IN THE WEST AND ALSO THE NORTH. THE BULK OF THE ENERGY ASSOCIATED WITH THE COLD FRONTS PARENT LOW WILL STAY NORTH OF THE REGION. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... THURSDAY NIGHT THE HIGH MOVES OFFSHORE AND A DEEP SURFACE LOW WILL MOVE OUT OF THE CENTRAL PLAINS. THIS WILL OPEN UP THE GULF AND WITH A STRONG LOW LEVEL JET MOISTURE WILL RETURN QUICKLY INTO THE TENNESSEE AND OHIO VALLEYS. WINDS WILL INCREASE OUT OF THE SOUTH THURSDAY NIGHT WITH GUSTS UP TO 35 MPH POSSIBLE AT HIGHER ELEVATIONS. 850 MB TEMPERATURES REMAIN IN THE +10 TO +13 DEGREE RANGE UNTIL THE FRONT COMES THROUGH ON SATURDAY. WILL GO ABOVE GUIDANCE FOR MAXIMUM TEMPERATURES THURSDAY AND FRIDAY. GFS IS SHOWING SIGNS IN THE RELATIVE HUMIDITY FORECASTS OF A PREFRONTAL LINE OF CONVECTION THAT REACHES THE EAST COAST BY SATURDAY EVENING. GFS ALSO HAS A SLIGHTLY DEEP SURFACE WAVE ALONG THE FRONT IN VIRGINIA ON SATURDAY MORNING THAN ON PRECIOUS RUNS WHICH MAY LEAD TO A SLOWER FRONTAL PASSAGE. THIS LINES UP CLOSE TO TIMING SHOWN ON THE ECMWF SO WILL BE INCREASING CHANCE OF PRECIPITATION ON FRIDAY NIGHT AND SATURDAY. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... HAVE USED BUFKIT FROM THE 06Z NAM AND RUC TO FINE TUNE WHEN STRATUS SHUD SCATTER OUT OF TAF SITES. EXPECT CLEARING TO MAKE IT FARTHER EAST THAN ON MONDAY. EDGE OF STRATUS IS ALREADY VERY CLOSE TO BLF SO EXPECT THEY WILL BECOME VFR BETWEEN 14-16Z. BROUGHT IFR TO LIFR CEILINGS BACK INTO THE TAFS AFTER 08Z BUT MOISTURE IS GETTING VERY SHALLOW. THIS SHOULD BE THE LAST NIGHT IN THE WEDGE. EVEN LYH WILL CLEAR OUT WITH VFR CONDITIONS ON WEDNESDAY. ON WED...ONCE SITES BREAK OUT WE WILL GET INTO THE WARM SECTOR AND SW FLOW...SO VFR CONDITIONS ARE EXPECTED AT ALL SITES BY AFTERNOON. A COLD FRONT WILL APPROACH THE REGION WED NIGHT...BUT IS EXPECTED TO STALL TO OUR NORTHWEST. BLF AND LWB WILL HAVE A CHANCE FOR MVFR SHOWERS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KM NEAR TERM...JJ SHORT TERM...DS LONG TERM...AMS AVIATION...AMS/DS/KK va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 149 PM CDT TUE APR 8 2008 .AVIATION... LOOK FOR VFR CONDITIONS TO DOMINATE WEST CENTRAL TEXAS UNTIL AROUND SUNSET THIS EVENING. AT THAT TIME...A SURFACE COLD FRONT...CURRENTLY MOVING SOUTHEAST ACROSS THE HEARTLAND AND NORTHERN EDWARDS PLATEAU...WILL STALL. WARM AND MOIST AIR WILL BEGIN MOVING BACK INTO WEST CENTRAL TEXAS FROM THE SOUTHEAST AND GLIDING UP AND OVER THE COOLER AIR NEAR THE SURFACE. BY MIDNIGHT TONIGHT...EXPECT MVFR CEILINGS TO DOMINATE WEST CENTRAL TEXAS. IN ADDITION...THUNDERSTORMS MAY DEVELOP LATER THIS AFTERNOON AND THIS EVENING...MAINLY EAST AND SOUTHEAST OF A LINE FROM ROBY...THROUGH SAN ANGELO...TO OZONA. AFTER MIDNIGHT TONIGHT...THUNDERSTORMS MAY DEVELOP ACROSS ALL OF WEST CENTRAL TEXAS. AFTER MIDNIGHT...THE BEST CHANCES FOR THUNDERSTORMS WILL BE MAINLY ALONG AND EAST OF A LINE FROM ROBY TO SONORA. AFTER SUNRISE TOMORROW MORNING...THE POTENTIAL FOR SEVERE THUNDERSTORMS WILL INCREASE ACROSS WEST CENTRAL TEXAS AS AN UPPER-LEVEL TROUGH OF LOW PRESSURE BEGINS TO MOVE ACROSS AND EAST OF THE SOUTHERN ROCKIES. 23/HUBER && .PREV DISCUSSION... /ISSUED 1155 AM CDT TUE APR 8 2008/ UPDATE... COLD FRONT CONTINUES TO PUSH SOUTH ACROSS WEST CENTRAL TEXAS THIS MORNING. TEMPERATURES BEHIND THE FRONT A MUCH COLDER THAN WE WERE PREVIOUSLY THINKING. FOR EXAMPLE...WE WERE THINKING THE TEMPERATURE WOULD BE AROUND 70 IN ABILENE BY NOON. AS OF 11 AM...THE TEMPERATURE THERE HAD FALLEN TO 58 DEGREES. ALSO...LOW CLOUDS ARE CLEARING SOONER THAN WE WERE THINKING. THE LATEST RUC APPEARS TO BE ON TRACK WITH THIS FRONT. DECIDED TO LOWER AFTERNOON HIGHS FOR TODAY...ESPECIALLY FOR THE CONCHO VALLEY. ALSO...ADJUSTED DEWPOINT...WIND...AND SKY GRIDS FOR THE REMAINDER OF TODAY TO BRING THEM MORE IN LINE WITH CURRENT OBSERVATIONS. LATEST ZONE AND POINT FORECAST MATRIX PRODUCTS REFLECT THESE ADJUSTMENTS. 23/HUBER PREV DISCUSSION... /ISSUED 628 AM CDT TUE APR 8 2008/ AVIATION... SOUTHERLY FLOW HAS TRANSPORTED LOW LEVEL MOISTURE NORTH ACROSS WEST CENTRAL TEXAS THIS MORNING. LLWS IS EXPECTED ACROSS THE AREA THROUGH 08/15Z...WITH SOUTH WINDS OF 40 KNOTS AT 2000 FEET. MVFR CIGS BKN020-030 ARE EXPECTED THROUGH 08/18Z ACROSS SOUTHERN AND EASTERN PARTS OF WEST CENTRAL TEXAS. MAINLY VFR CONDITIONS THIS AFTERNOON. A COLD FRONT WILL MOVE SOUTH ACROSS WEST CENTRAL TEXAS TODAY AND TONIGHT...WITH ISOLD TSTMS POSSIBLE. MVFR CIGS WILL DEVELOP ACROSS WEST CENTRAL TEXAS AFTER 09/04Z. 21 PREV DISCUSSION... /ISSUED 344 AM CDT TUE APR 8 2008/ DISCUSSION... THE MAIN FORECAST CHALLENGES CENTER ON TSTORM CHANCES AND SEVERITY FROM THIS AFTERNOON THROUGH WEDNESDAY NIGHT. HOW COOL TEMPERATURES WILL BE OVER THE WEEKEND AND EARLY NEXT WEEK WILL ALSO BE A CHALLENGE. AS OF 3 AM...A SURFACE LOW WAS LOCATED NEAR ASPERMONT AND A COLD FRONT WAS SURGING SOUTH ACROSS THE TX PANHANDLE AND SOUTHERN OK. THE SURFACE LOW WILL MOVE EAST AND THEN NORTHEAST ALONG THE BAROCLINIC ZONE TODAY AND THE FRONT WILL PUSH SOUTH INTO THE REGION. BY THIS AFTERNOON...WIDELY SCATTERED THUNDERSTORM DEVELOPMENT IS LIKELY ALONG THE FRONT FROM NORTHEAST TX DOWN INTO THE HEARTLAND AND NORTHWEST HILL COUNTRY. THE BETTER CHCS OF STORMS WILL BE EAST OF MY FCST AREA THIS AFTERNOON. IF STORMS DO DEVELOP THERE IS ENUF VERTICAL SHEAR FOR SEVERE...MAINLY IN THE FORM OF HAIL/WINDS DUE TO WEAK LOW LEVEL SHEAR. THE GFS SUGGESTS THAT STORMS MAY BACKBUILD INTO THE AREA TONIGHT AS THE FRONT STALLS. THERE WILL BE AT LEAST SMALL CHCS OF STORMS ALONG AND NORTH OF THIS FRONT AS A STRENGTHENING SOUTHERLY LLJ INTERACTS WITH IT. CHC OF CONVECTION NORTH OF THE FRONT INCREASE WEDNESDAY MORNING WITH STRENGTHENING ISENTROPIC LIFT/MOISTURE TRANSPORT PER THE GFS. ANY OF THESE ELEVATED STORMS COULD PRODUCE SEVERE HAIL GIVEN THE STEEP LAPSE RATES AND GOOD SHEAR ALOFT. WHAT IS OF MOST INTEREST IS HOW THE SURFACE BOUNDARIES EVOLVE WEDNESDAY AFTERNOON AS A POWERFUL UPPER LEVEL TROUGH MOVES EAST INTO THE SOUTHERN PLAINS. CURRENT INDICATIONS ARE THAT THE WARM FRONT WILL LIFT NORTH DURING THE DAY OWING TO CYCLOGENESIS OVER THE SOUTHERN HIGH PLAINS IN THE LEFT EXIT REGION OF APPROACHING UPPER JET. A DRYLINE WILL MIX EAST TO AROUND MY WESTERN BORDER COUNTIES SOUTH OF THE LOW. MODEL SOUNDINGS IN THE WARM SECTOR SHOW SOME CAP BUT DEFINITELY BREAKABLE. SO THE CURRENT THINKING IS THAT STORMS WILL INITIATE ALONG THE DRYLINE...ESPECIALLY NEAR THE INTERSECTION WITH THE WARM FRONT. EXACTLY WHERE THIS WILL BE IS STILL UNCERTAIN...BUT IT VERY WELL COULD BE CLOSE TO MY NORTHWESTERN COUNTIES. ASSUMING STORMS WILL INITIATE...MODEL SOUNDINGS SHOW UP TO 3000 J/KG OF CAPE AND GREAT SHEAR FROM 0 TO 6 KM WITH A CLASSIC VEERING PROFILE WITH HEIGHT. SO SUPERCELL STORMS CAPABLE OF PRODUCING VERY LARGE HAIL AND TORNADOES ARE IN THE CARDS. THE BETTER RISK OF TORNADOES WILL NEAR THE SURFACE WARM FRONT WHERE THE LOW LEVEL SHEAR IS A BIT BETTER DURING THE AFTERNOON AND ACROSS ALL AREAS TOWARD EVENING WITH ANY DISCREET CELLS DUE TO THE STRENGTHENING LLJ AND RESULTANT 0-1KM SHEAR. GIVEN THE AMOUNT OF INSTABILITY THERE COULD BE A STRONG TORNADO OR TWO. THE CONVECTION IS EXPECTED TO BECOME A SQUALL LINE WEDNESDAY NIGHT AS THE PACIFIC FRONT SWEEPS EAST ACROSS THE AREA. THE SEVERE RISK MAY THEN TRANSITION TO A HAIL/WIND THREAT DURING THE NIGHT. THE ACTIVITY SHOULD BE PRETTY MUCH DONE BY 12Z THURSDAY. THE REMAINDER OF THE FORECAST WILL BE TRANQUIL WITH THE MAIN CHALLENGE BEING TEMPS. THE WEDNESDAY SYSTEM WILL LIFT NORTHEAST AND CLOSE OFF OVER THE CENTRAL PLAINS ON THURSDAY AND THEN LIFT UP INTO THE GREAT LAKES...HELPING TO CARVE OUT A DEEP LONGWAVE TROUGH OVER THE CENTRAL PART OF THE COUNTRY. OVER THE WEEKEND...BOTH THE GFS/ECMWF BRING A PIECE OF ENERGY SOUTHEAST ACROSS THE SOUTHERN PLAINS ON THE BACK SIDE OF THE TROUGH AND THIS WILL BRING SOME FAIRLY COOL CANADIAN AIR SOUTH INTO TEXAS BEGINNING AS EARLY AS THURSDAY NIGHT WITH THE ARRIVAL OF THE POLAR FRONT. BASED ON THE LATEST 850MB PROGS FROM THE GFS/ECMWF HIGHS AND LOWS WERE LOWERED...WITH THE ECMWF EVEN SUGGESTING COOLER TEMPS THAT WHAT IS IN THE GRIDS. TEMPS WILL GRADUALLY MODIFY EARLY NEXT WEEK AS THE LONGWAVE TROUGH SHIFTS EAST. LACY && .PRELIMINARY POINT TEMPS/POPS... ABILENE 53 76 61 78 / 30 50 60 10 SAN ANGELO 59 84 62 81 / 20 40 60 0 JUNCTION 64 79 65 86 / 30 20 40 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/HUBER tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1155 AM CDT TUE APR 8 2008 .UPDATE... COLD FRONT CONTINUES TO PUSH SOUTH ACROSS WEST CENTRAL TEXAS THIS MORNING. TEMPERATURES BEHIND THE FRONT A MUCH COLDER THAN WE WERE PREVIOUSLY THINKING. FOR EXAMPLE...WE WERE THINKING THE TEMPERATURE WOULD BE AROUND 70 IN ABILENE BY NOON. AS OF 11 AM...THE TEMPERATURE THERE HAD FALLEN TO 58 DEGREES. ALSO...LOW CLOUDS ARE CLEARING SOONER THAN WE WERE THINKING. THE LATEST RUC APPEARS TO BE ON TRACK WITH THIS FRONT. DECIDED TO LOWER AFTERNOON HIGHS FOR TODAY...ESPECIALLY FOR THE CONCHO VALLEY. ALSO...ADJUSTED DEWPOINT...WIND...AND SKY GRIDS FOR THE REMAINDER OF TODAY TO BRING THEM MORE IN LINE WITH CURRENT OBSERVATIONS. LATEST ZONE AND POINT FORECAST MATRIX PRODUCTS REFLECT THESE ADJUSTMENTS. 23/HUBER && .PREV DISCUSSION... /ISSUED 628 AM CDT TUE APR 8 2008/ AVIATION... SOUTHERLY FLOW HAS TRANSPORTED LOW LEVEL MOISTURE NORTH ACROSS WEST CENTRAL TEXAS THIS MORNING. LLWS IS EXPECTED ACROSS THE AREA THROUGH 08/15Z...WITH SOUTH WINDS OF 40 KNOTS AT 2000 FEET. MVFR CIGS BKN020-030 ARE EXPECTED THROUGH 08/18Z ACROSS SOUTHERN AND EASTERN PARTS OF WEST CENTRAL TEXAS. MAINLY VFR CONDITIONS THIS AFTERNOON. A COLD FRONT WILL MOVE SOUTH ACROSS WEST CENTRAL TEXAS TODAY AND TONIGHT...WITH ISOLD TSTMS POSSIBLE. MVFR CIGS WILL DEVELOP ACROSS WEST CENTRAL TEXAS AFTER 09/04Z. 21 PREV DISCUSSION... /ISSUED 344 AM CDT TUE APR 8 2008/ DISCUSSION... THE MAIN FORECAST CHALLENGES CENTER ON TSTORM CHANCES AND SEVERITY FROM THIS AFTERNOON THROUGH WEDNESDAY NIGHT. HOW COOL TEMPERATURES WILL BE OVER THE WEEKEND AND EARLY NEXT WEEK WILL ALSO BE A CHALLENGE. AS OF 3 AM...A SURFACE LOW WAS LOCATED NEAR ASPERMONT AND A COLD FRONT WAS SURGING SOUTH ACROSS THE TX PANHANDLE AND SOUTHERN OK. THE SURFACE LOW WILL MOVE EAST AND THEN NORTHEAST ALONG THE BAROCLINIC ZONE TODAY AND THE FRONT WILL PUSH SOUTH INTO THE REGION. BY THIS AFTERNOON...WIDELY SCATTERED THUNDERSTORM DEVELOPMENT IS LIKELY ALONG THE FRONT FROM NORTHEAST TX DOWN INTO THE HEARTLAND AND NORTHWEST HILL COUNTRY. THE BETTER CHCS OF STORMS WILL BE EAST OF MY FCST AREA THIS AFTERNOON. IF STORMS DO DEVELOP THERE IS ENUF VERTICAL SHEAR FOR SEVERE...MAINLY IN THE FORM OF HAIL/WINDS DUE TO WEAK LOW LEVEL SHEAR. THE GFS SUGGESTS THAT STORMS MAY BACKBUILD INTO THE AREA TONIGHT AS THE FRONT STALLS. THERE WILL BE AT LEAST SMALL CHCS OF STORMS ALONG AND NORTH OF THIS FRONT AS A STRENGTHENING SOUTHERLY LLJ INTERACTS WITH IT. CHC OF CONVECTION NORTH OF THE FRONT INCREASE WEDNESDAY MORNING WITH STRENGTHENING ISENTROPIC LIFT/MOISTURE TRANSPORT PER THE GFS. ANY OF THESE ELEVATED STORMS COULD PRODUCE SEVERE HAIL GIVEN THE STEEP LAPSE RATES AND GOOD SHEAR ALOFT. WHAT IS OF MOST INTEREST IS HOW THE SURFACE BOUNDARIES EVOLVE WEDNESDAY AFTERNOON AS A POWERFUL UPPER LEVEL TROUGH MOVES EAST INTO THE SOUTHERN PLAINS. CURRENT INDICATIONS ARE THAT THE WARM FRONT WILL LIFT NORTH DURING THE DAY OWING TO CYCLOGENESIS OVER THE SOUTHERN HIGH PLAINS IN THE LEFT EXIT REGION OF APPROACHING UPPER JET. A DRYLINE WILL MIX EAST TO AROUND MY WESTERN BORDER COUNTIES SOUTH OF THE LOW. MODEL SOUNDINGS IN THE WARM SECTOR SHOW SOME CAP BUT DEFINITELY BREAKABLE. SO THE CURRENT THINKING IS THAT STORMS WILL INITIATE ALONG THE DRYLINE...ESPECIALLY NEAR THE INTERSECTION WITH THE WARM FRONT. EXACTLY WHERE THIS WILL BE IS STILL UNCERTAIN...BUT IT VERY WELL COULD BE CLOSE TO MY NORTHWESTERN COUNTIES. ASSUMING STORMS WILL INITIATE...MODEL SOUNDINGS SHOW UP TO 3000 J/KG OF CAPE AND GREAT SHEAR FROM 0 TO 6 KM WITH A CLASSIC VEERING PROFILE WITH HEIGHT. SO SUPERCELL STORMS CAPABLE OF PRODUCING VERY LARGE HAIL AND TORNADOES ARE IN THE CARDS. THE BETTER RISK OF TORNADOES WILL NEAR THE SURFACE WARM FRONT WHERE THE LOW LEVEL SHEAR IS A BIT BETTER DURING THE AFTERNOON AND ACROSS ALL AREAS TOWARD EVENING WITH ANY DISCREET CELLS DUE TO THE STRENGTHENING LLJ AND RESULTANT 0-1KM SHEAR. GIVEN THE AMOUNT OF INSTABILITY THERE COULD BE A STRONG TORNADO OR TWO. THE CONVECTION IS EXPECTED TO BECOME A SQUALL LINE WEDNESDAY NIGHT AS THE PACIFIC FRONT SWEEPS EAST ACROSS THE AREA. THE SEVERE RISK MAY THEN TRANSITION TO A HAIL/WIND THREAT DURING THE NIGHT. THE ACTIVITY SHOULD BE PRETTY MUCH DONE BY 12Z THURSDAY. THE REMAINDER OF THE FORECAST WILL BE TRANQUIL WITH THE MAIN CHALLENGE BEING TEMPS. THE WEDNESDAY SYSTEM WILL LIFT NORTHEAST AND CLOSE OFF OVER THE CENTRAL PLAINS ON THURSDAY AND THEN LIFT UP INTO THE GREAT LAKES...HELPING TO CARVE OUT A DEEP LONGWAVE TROUGH OVER THE CENTRAL PART OF THE COUNTRY. OVER THE WEEKEND...BOTH THE GFS/ECMWF BRING A PIECE OF ENERGY SOUTHEAST ACROSS THE SOUTHERN PLAINS ON THE BACK SIDE OF THE TROUGH AND THIS WILL BRING SOME FAIRLY COOL CANADIAN AIR SOUTH INTO TEXAS BEGINNING AS EARLY AS THURSDAY NIGHT WITH THE ARRIVAL OF THE POLAR FRONT. BASED ON THE LATEST 850MB PROGS FROM THE GFS/ECMWF HIGHS AND LOWS WERE LOWERED...WITH THE ECMWF EVEN SUGGESTING COOLER TEMPS THAT WHAT IS IN THE GRIDS. TEMPS WILL GRADUALLY MODIFY EARLY NEXT WEEK AS THE LONGWAVE TROUGH SHIFTS EAST. LACY && .PRELIMINARY POINT TEMPS/POPS... ABILENE 77 53 76 61 / 20 30 50 60 SAN ANGELO 83 59 84 62 / 10 20 40 60 JUNCTION 84 64 79 65 / 10 30 20 40 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/HUBER tx