AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 240 PM MDT SAT APR 19 2008 .SHORT TERM...UPPER TROUGH MOVING INTO GREAT BASIN IS INCREASING THE SOUTHWEST FLOW ALOFT OVER AREA. ACROSS PLAINS...SOUTHERLY WINDS HAVE DEVELOPED IN RESPONSE TO SURFACE HIGH OVER KANSAS...AND HAVE BECOME A BIT GUSTY AS THE STRONGER WINDS MIXED TO THE SURFACE. DEWPOINTS HAVE DROPPED INTO THE TEENS MOST AREAS OF THE PLAINS WITH HUMIDITY READINGS AROUND 15% OR LESS. LATEST RUC INDICATES LITTLE CHANGE IN CURRENT CONDITIONS THROUGH 00Z...WILL KEEP RED FLAG WARNING GOING TILL 02Z FOR PLAINS. AFTER THAT...SURFACE WINDS DECREASE A BIT WITH INCREASING DEWPOINTS AS LOW LEVEL MOISTURE GETS ADVECTED INTO AREA. AS FOR MOUNTAINS...GUSTY WINDS TO CONTINUE...ESPECIALLY OVER THE RIDGES. SOME HIGH LEVEL MOISTURE MOVES ACROSS AREA...NOT ENOUGH TO MAKE ANY IMPACT. ON SUNDAY...SOUTHWEST FLOW ALOFT WILL CONTINUE TO INCREASE AS TROUGH MOVES CLOSER TO COLORADO. MODEL CROSS SECTIONS CONTINUE TO SHOW A BATCH OF MID LEVEL MOISTURE MOVING INTO MOUNTAINS DURING THE AFTERNOON...APPEARS TO BE ASSOCIATED WITH A WEAK SHORTWAVE. MODELS SHOW SOME QG ASCENT OVER MOUNTAINS AT THAT TIME. WITH LAPSE RATES AROUND 8 C/KM...COULD SEE SOME AFTERNOON BUILDUPS. NOT EXPECTING ANY PRECIP AT THIS TIME...SO WILL KEEP POPS ZERO. MAIN CONCERN AGAIN WILL BE FIRE WEATHER ISSUES ACROSS PLAINS DURING AFTERNOON...AS GUSTY SOUTHWEST WINDS EXPECTED TO DEVELOP WITH RELATIVE HUMIDITY READINGS IN THE TEENS. TO AVOID ANY CONFUSION WITH CURRENT RED FLAG WARNING...WILL LET THE EVENING CREW HOIST THE HILIGHT FOR TOMORROW AFTER TODAY`S WARNING ENDS. GUIDANCE TEMPERATURES LOOK A BIT TOO COOL GIVEN THE INCREASE IN SOUTHWEST WINDS. CURRENT TEMPERATURE GRIDS SEEM MORE REASONABLE...WILL MAKE MINIMAL CHANGES. .LONG TERM...LARGE SCALE TROUGH OVER THE PACIFIC NORTHWEST WILL SPIT SOME ENERGY OUR WAY FROM TIME TO TIME EARLY IN THE PERIOD WITH MOST OF IT HEADING ACROSS WYOMING. EXACT TIMING OF THESE FEATURES IS LESS THAN EXACT BUT IT WOULD APPEAR THAT THE IMPACT ON OUR AREA WON/T BE TERRIBLY SIGNIFICANT...SLIGHT CHANCE OF SOME PRECIPITATION ...COOLER TEMPERATURES AND SOME INCREASE IN THE WINDS APPEARS TO BE ABOUT IT. THE COOLER TEMPERATURES AND ASSOCIATED HIGHER RELATIVE HUMIDITIES WILL ALLEVIATE THE FIRE WEATHER PROBLEMS THAT WE ARE PRESENTLY EXPERIENCING. TOWARDS MIDWEEK THE MODELS SUGGEST THAT A RIDGE MAY BUILD INTO THE PACIFIC NORTHWEST FORCING A STRONGER TROUGH ACROSS THE CENTRAL ROCKIES. HAVE MADE RELATIVELY MINOR CHANGES TO THE GRIDS IN THE LONGER TERM TO REFLECT THESE THOUGHTS. && .AVIATION...VFR CONDITIONS EXPECTED THROUGH SUNDAY. SOUTHERLY SURFACE GRADIENT ACROSS PLAINS TO WEAKEN AFTER 00Z WITH SURFACE WINDS DECREASING AND DRAINAGE PATTERN DEVELOPING. SOUTHWEST WINDS TO INCREASE AFTER 18Z...WITH SOME GUSTS TO 30 KTS EXPECTED AT THE LOCAL AIRPORTS. && .BOU WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING UNTIL 02Z FOR NORTHEAST PLAINS...COZ238>251. && $$ D-L/ET co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 310 AM MDT FRI APR 18 2008 .SHORT TERM....DRY AND STABLE CONDITIONS WILL PREVAIL TODAY AS TEMPERATURES RETURN TO NEAR AVERAGE FOR THE DATE. HIGH PRESSURE RIDGE TO OUR WEST THIS MORNING WILL CONTINUE TO BUILD EASTWARD OVER THE CWFA DURING THE DAY. MODERATE NORTHWESTERLY FLOW AT MID-LEVEL WILL GRADUALLY TURN WESTERLY AS THE DAY PROGRESSES. CROSS SECTIONS SHOW THE FORMATION OF A WEAK MOUNTAIN WAVE OVER THE FRONT RANGE AS MTN TOP STATIC STABILITY STRENGTHENS WITH WARMING ALOFT. RUC AND NAM ALSO INDICATE WEAK PRESSURE FALLS ALONG THE BASE OF THE FRONT RANGE TODAY...TOGETHER WITH THE WLY FLOW ALOFT SHOULD OCCASIONALLY PRODUCE GUSTY DOWNSLOPE WINDS IN AND NEAR THE FOOTHILLS. STRONG DIABATIC HEATING WITH AMPLE SUNSHINE AND THE ADDITIONAL HEATING PRODUCED BY THE DOWNSLOPE FLOW WILL WARM TEMPERATURES BACK INTO THE 60S ON THE PLAINS...WITH THE WARMEST READING WITHIN THE URBAN CORRIDOR AND ALONG THE SOUTH PLATTE. OVERNIGHT WOULD EXPECT TO SEE GUSTY DOWNSLOPE WINDS CONTINUING IN AND NEAR THE BASE OF THE FRONT RANGE...THOUGH SPEEDS WILL REMAIN WELL BELOW HIGH WIND CRITERIA. OTHERWISE EXCEPT FOR SOME MID-LEVEL MTN WAVE CLOUDINESS OVER THE FOOTHILLS LATE...CLEAR SKIES AND SEASONABLY COOL TEMPERATURES WILL BE THE RULE. .LONG TERM...RIDGE AXIS ALOFT SHIFTS EAST OUT ACROSS THE CENTRAL PLAINS THIS WEEKEND AS BROAD UPPER LEVEL TROF BEGINS TO CARVE OUT ACROSS THE NRN GREAT BASIN. FLOW ALOFT WILL INCREASE FROM THE SOUTHWEST AHEAD OF THE TROF. MAIN ISSUE WILL BE INCREASED FIRE WEATHER CONCERNS WITH LOWERING RH AND INCREASING SFC WINDS BY SAT AFTN AND AGAIN FOR SUN AFTERNOON. AFTER CONSULTING WITH ADJOINING OFFICES WILL HOLD OFF ON ANY WATCHES FOR NOW. RECENT PRECIP AND NEW GRASS GROWTH OVER THE PLAINS WOULD PLAY AGAINST CRITICAL FIRE BEHAVIOR. SO WILL LET LATER SHIFTS GATHER INFORMATION ON STATUS OF FUELS TO DECIDE IF A WATCH IS NECESSARY. THERE WILL BE SOME SLIGHT COOLING OVER THE FRONT RANGE ON SUNDAY AS A LEAD WAVE EJECTS OUT FROM THE LOW WITH MORE MID LVL DRYING ON SUNDAY. A STRONGER FRONT WILL MOVE ACROSS EASTERN CO ON SUNDAY NIGHT WITH MORE COOLING FOR MONDAY. MOISTURE THRU EARLY NEXT WEEK REMAINS QUITE SCARCE BUT WILL LEAVE ISOLD SHOWERS IN THE NRN MOUNTAINS FOR NOW. THE MIDDLE OF THE WEEK IS A BIT MORE FUZZY AS JET STREAK AND ADDITIONAL TROFINESS MOVE ACROSS THE REGION LATE TUESDAY THROUGH THURSDAY. GFS IS SHOWING SOME QPF EACH OF THESE DAYS BUT WON`T ADD ANY TO GRIDS YET TIL WE GET SOME BETTER DETAIL. && .AVIATION...HIGH PRESSURE ALOFT AND A WEAK LOW PRESSURE TROUGH ALONG THE FOOT OF THE FRONT RANGE WILL RESULT IN PERIODS OF GUSTY WEST WINDS IN THE NEAR THE FOOTHILLS THIS AFTERNOON AND TONIGHT. EXPECT VFR CONDITIONS IN THE DENVER AREA DURING THE NEXT 24 HOURS AS THE ATMOSPHERE REMAINS DRY AND STABLE. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE && $$ BAKER/ENTREKIN co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 800 PM EDT FRI APR 18 2008 .UPDATE... 00Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN ACTIVE UPPER LEVEL PATTERN ACROSS THE CONUS THIS EVENING. MAIN FEATURE OF NOTE BEING THE POTENT NEGATIVELY TILTED TROUGH ALONG THE MISSISSIPPI RIVER VALLEY WITH AN EMBEDDED CLOSED LOW OVER MISSOURI. LARGE SCALE RIDGING IS SEEN BOTH TO THE WEST AND EAST OF THIS FEATURE OVER THE SOUTHWESTERN STATES AND ALONG THE EAST COAST. ADDITIONAL SHORTWAVE ENERGY IS NOW PUSHING SOUTH INTO WASHINGTON AND OREGON FROM THE COAST OF BRITISH COLUMBIA. AT THE SURFACE...COLD FRONT EXTENDS SOUTHWARD FROM LOW PRESSURE OVER THE MIDDLE/NORTHERN MISSISSIPPI VALLEY TO THE MISSISSIPPI DELTA REGION. LARGE SCALE ASSENT ALONG THE EASTERN PERIPHERY OF THE MID/UPPER LEVEL TROUGH IS HELPING TO SUPPORT A BAND OF SHOWERS/TSTORMS FROM THE WESTERN TENNESSEE VALLEY SOUTHWARD TO MS/WESTERN AL. CLOSER TO HOME...HIGH PRESSURE CONTINUES TO GIVE UP INFLUENCE OVER THE FORECAST AREA AS IT SLIPS FURTHER OFF THE SOUTHEAST COAST. COLD FRONT TO OUR WEST WILL SLIDE EAST OVERNIGHT REACHING OUR WESTERN ZONES AROUND OR JUST BEFORE DAWN. BAND OF SHOWERS/STORMS ALONG THIS FRONT WILL PUSH EAST AS WELL WITH CHANCE/LIKELY POPS WEST OF THE APALACHICOLA RIVER AFTER MIDNIGHT. ONE OR TWO OF THESE STORMS MAY BE ON THE STRONG SIDE ALTHOUGH THE BEST FORCING FOR THE SCT SEVERE STORMS TO OUR WEST WILL BE WEAKENING WITH TIME. A FEW MORE ISOLATED SHOWERS WILL BE POSSIBLE DURING THE LATE NIGHT HOURS AS FAR EAST AS A LINE FROM KTLH TO TIFTON GA...ALTHOUGH MOST OF THE SHOWERS WILL HOLD OFF UNTIL AFTER SUNRISE FOR CENTRAL PORTIONS OF THE FORECAST AREA. COLD FRONT WILL THEN PROGRESS ACROSS THE REST OF THE FORECAST AREA DURING THE LATER MORNING AND AFTERNOON BEFORE EXITING THE SOUTHEAST BIG BEND DURING THE EARLY EVENING. BAND OF SHOWERS/STORMS IS EXPECTED TO WEAKEN THROUGH THE DAY AS ALL GLOBAL GUIDANCE SUGGESTING THAT LARGE SCALE ASSENT WILL CONTINUE TO WEAKEN ALONG THE FRONT THROUGH THE DAY. MAY ONLY BE LOOKING AT A BROKEN AND THIN LINE OF SHOWERS FOR THE AFTERNOON ACROSS THE EASTERN HALF OF THE AREA. LOOK FOR SKIES TO AT LEAST PARTIALLY CLEAR FROM WEST TO EAST LATE FRIDAY AFTERNOON INTO FRIDAY NIGHT AS HIGH PRESSURE BUILDS OVERHEAD FROM THE WEST. LOW TEMPERATURES TONIGHT STILL EXPECTED TO BOTTOM OUT IN THE MIDDLE TO UPPER 50S INLAND AND LOWER TO MIDDLE 60S ALONG THE COAST. HIGH TEMPS FOR SATURDAY GENERALLY IN THE 70S. A FEW SPOTS ACROSS OUR FAR EASTERN ZONES OF THE FL BIG BEND AND SOUTH-CENTRAL GA MAY APPROACH 80 IF SHOWER ACTIVITY CAN HOLD OFF UNTIL THE AFTERNOON. && .AVIATION... AFTERNOON CU FIELD SHOULD DISSIPATE EARLY IN THE EVENING WITH THE SETTING SUN. HOWEVER...CLOUDS WILL RETURN AFTERN MIDNIGHT AS COLD FRONT APPROACHES FROM THE WEST. CIGS WILL GRADUALLY LOWER OVERNIGHT INTO THE MORNING...REACHING MVFR CRITERIA. SCATTERED SHOWERS WILL AFFECT WESTERN TERMINALS BY SUNRISE WITH SHOWERS AND THUNDERSTORMS ELSEWHERE DURING THE MORNING HOURS. ACTIVITY SHOULD EXIT THE REGION BY LATE AFTERNOON. && .MARINE... SOUTHERLY FLOW WILL CONTINUE THROUGH MUCH OF THE NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. FLOW MAY AT TIMES REACH CAUTION CRITERIA BETWEEN 15 AND 20 KNOTS. BUOY 43039 TO THE SOUTH OF PANAMA CITY WAS SUSTAINED AT 17 KNOTS LAST HOUR...SO WILL UPDATE THE COASTAL WATERS FORECAST TO ADD THE CAUTION HEADLINE. COLD FRONT ENTERS THE WESTERN WATERS EARLY ON SATURDAY AND EXITS TO THE SOUTH AND EAST DURING THE LATE AFTERNOON/EARLY EVENING. WINDS BEHIND THE FRONT COMING AROUND TO THE WEST BETWEEN 10 AND 15 KNOTS. FLOW BECOMES QUITE LIGHT FOR THE SECOND HALF OF THE UPCOMING WEEKEND AS HIGH PRESSURE BUILDS OVER THE FORECAST WATERS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 57 79 51 83 53 / 30 50 0 0 0 PANAMA CITY 63 76 59 79 61 / 50 50 0 0 0 DOTHAN 59 76 53 82 56 / 70 40 0 0 0 ALBANY 57 77 51 82 53 / 40 50 0 0 0 VALDOSTA 56 79 55 82 53 / 20 40 05 0 0 CROSS CITY 56 79 55 82 54 / 05 20 05 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE...FRANKLIN... GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON... JEFFERSON...LAFAYETTE...LEON...LIBERTY...MADISON... TAYLOR...WAKULLA...WASHINGTON. && $$ PUBLIC/MARINE...MROCZKA AVIATION...CAMP fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 830 PM CDT SAT APR 19 2008 .DISCUSSION... ISSUED 830 PM CDT SAT APR 19 2008 LOW PRESSURE NOW CENTERED NEAR CHICAGO AND SLOPES UP TO SOUTHERN INDIANA IN THE MID/UPPER LEVELS. SURFACE TROUGH PREVIOUSLY ANALYZED FROM THE LOW SOUTHWARD THROUGH CENTRAL ILLINOIS HAS BECOME LESS DISTINCT AS WINDS DECREASE. DRIER AIRMASS OVER THE EASTERN HALF OF THE AREA WITH AFTERNOON DEWPOINTS IN THE LOW/MID 40S IS NOW MOISTENING UP WITH DEWPOINTS NOW RISING TOWARD 50. MANY AREAS EAST OF INTERSTATE 55 HAVE CLEARED OUT...WHICH WILL PROMOTE RADIATIONAL COOLING THIS EVENING. ALL OF THESE FACTORS WILL FAVOR THE FORMATION OF FOG OVERNIGHT...WHICH WILL LIKELY BE DENSE OVER MANY AREAS. FORECAST SOUNDINGS FROM THE SHORT-RANGE RUC MODEL SUPPORT THIS SCENERIO AS WELL. WOULD NOT BE SURPRISED IF A DENSE FOG ADVISORY BECOMES REQUIRED LATER TONIGHT...BUT WILL HOLD OFF ON ANY ISSUANCE UNTIL THE AERIAL EXTENT BECOMES BETTER DEFINED. AREAS OF THE WEST THAT DID NOT REALLY CLEAR OUT MAY NOT MEET ADVISORY CRITERIA. FORECASTS ALREADY MENTION FOG FOR TONIGHT...SO WILL LET THAT RIDE FOR THE MOMENT. RADAR DATA SHOWS ONLY A FEW WEAKENING SPITS OF DRIZZLE HERE AND THERE SO NO NEED TO MAKE CHANGES IN THE POPS...WHICH HAVE SLIGHT CHANCE ENDING AT MIDNIGHT. WILL SEND OUT A ZONE FORECAST UPDATE LATER THIS EVENING TO FRESHEN UP THE TEMPORAL WORDING...AND WILL ALSO MONITOR FOG TRENDS FOR ANY NEEDED ADVISORIES. 04 && .AVIATION... ISSUED 615 PM CDT SAT APR 19 2008 WEAK SURFACE LOW W OF ORD WITH TROUGH SWD TO STL. MOST CENTRAL ILLINOIS TERMINALS HAVE BECOME VFR THIS AFTERNOON EXCEPT FOR SPI... WHERE A BAND OF LIGHT RAIN AND IFR CONDITIONS CONTINUE. FAIRLY SOLID AREA OF MVFR CIGS OVER WESTERN ILLINOIS...AND THIS WILL PROBABLY DRIFT EASTWARD A LITTLE THIS EVENING WITHIN THE WESTERLY FLOW BEHIND THE SURFACE TROUGH. MAIN IMPACTS WILL BE AT PIA/SPI. EASTERN TERMINALS MAY NOT SEE THIS BATCH OF LOW CLOUDS...HOWEVER EXPECT FAIRLY WIDESPREAD FOG TO DEVELOP LATER TONIGHT WITH VSBYS 1SM OR LESS ALONG WITH AREAS OF STRATUS AT OR BELOW 500 FT. THE LOW CONDITIONS WILL LIKELY PERSIST TOWARD 15Z SUN...THEN THE MOISTURE SHOULD LIFT INTO A SCT-BKN STRATOCU DECK 2K-3K FT AND GRADUALLY BECOME BKN VFR AFTER 20Z SUN. 04 && .PREV DISCUSSION... ISSUED 305 PM CDT SAT APR 19 2008 SHORT TERM...TONIGHT THROUGH MONDAY. UPPER LOW WAS LOCATED JUST EAST OF MATTOON THIS AFTERNOON...WITH THE CIRCULATION SHOWING UP RATHER NICELY ON VISIBLE SATELLITE IMAGERY. MSAS INDICATED SFC LOW OVER NORTHERN ILLINOIS HAD WEAKENED TO AN OPEN TROUGH AT 2 PM...AND SFC WIND FIELDS SUGGEST WEAK CIRCULATION AT THE SFC ROUGHLY CO-LOCATED WITH THE UPPER LOW NEAR MATTOON. PLENTY OF BREAKS HAVE DEVELOPED IN THE CLOUD COVER ACROSS THE REGION... ESPECIALLY NORTH AND WEST OF THE I-72 CORRIDOR. IN AREAS WHERE THE SUN HAS PEEKED THROUGH...TEMPERATURES HAVE QUICKLY REBOUNDED INTO THE LOWER AND MIDDLE 60S. A FEW HEAVIER CONVECTIVE SHOWERS HAVE DEVELOPED NORTHWEST OF THE ILLINOIS RIVER WHERE TEMPS HAVE REBOUNDED THE MOST. IL STATE POLICE EARLIER REPORTED FUNNEL CLOUDS ASSOCIATED WITH A CONVECTIVE CELL OVER LA SALLE COUNTY IN THE LOT CWA. LAPS ANALYSIS INDICATES NON-SUPERCELL TORNADO PARAMETER OF 1.0+ OVER THAT AREA ... NOT SURPRISING GIVEN SFC TEMP OF 64F AT KVYS LEADING TO GREATER INSTABILITY WITHIN AN ARC OF ENHANCED STRETCHING POTENTIAL THAT EXISTS ACROSS THE ILLINOIS VALLEY PER LAPS. ALL THIS MAKES SENSE CONSIDERING ENHANCED VORTICITY WITH UPPER LOW OVER THE AREA. GIVEN OBSERVATIONS...WOULD NOT BE ENTIRELY SURPRISED TO SEE A FUNNEL CLOUD REPORT SHOULD WE MANAGE TO GET SOME HEAVIER CONVECTIVE CELLS TO DEVELOP. HIGHEST RISK WOULD BE NORTHWEST OF THE I-55 CORRIDOR... ESPECIALLY NEAR THE ILLINOIS RIVER. THIS RISK SHOULD DIMINISH AFTER SUNDOWN... AND ANY REMAINING SHOWERS SHOULD DISSIPATE SHORTLY AFTER SUNDOWN AS WELL. DRIER WX AND WARMING TEMPS ON TAP FOR SUNDAY AND MONDAY AS SHORTWAVE RIDGING DEVELOPS ACROSS THE MISSISSIPPI VALLEY IN THE WAKE OF OUR DEPARTING UPPER LOW. CU RULE AND MODEL SOUNDINGS SUGGEST A FEW BANDS OF ENHANCED CU DEVELOPMENT TOMORROW AFTERNOON...BUT OVERALL EXPECT PARTLY CLOUDY SKIES AND TEMPS WITHIN A COUPLE DEGREES EITHER SIDE OF 70 F. LONG TERM...TUESDAY THROUGH SATURDAY. LONGER RANGE MODELS STILL DEPICTING STRONG RIDGING ACROSS THE NORTHWEST PACIFIC INTO MAINLAND ALASKA THROUGH THE END OF NEXT WEEK. THIS WILL SUPPORT CONTINUED TROUGHING ACROSS THE WESTERN HALF OF THE CONUS...BUT PERSISTENT RIDGE EAST OF THE APPALACHIANS WILL PREVENT ANY REALLY STRONG DISTURBANCES FROM COMING THROUGH. WEAK UPPER LEVEL DISTURBANCE WILL RIDE OFF TO OUR NORTHWEST PUSHING A SLOW MOVING COLD FRONT THROUGH THE AREA TUESDAY. LONGER RANGE MODELS SHOW SOME DIFFERENCES WITH TIMING...BUT SUGGEST A PACIFIC DISTURBANCE UNDERCUTTING THE BLOCKING RIDGE OFF THE WEST COAST...WILL APPROACH THE AREA FRIDAY...POSSIBLY FOLLOWED BY A STRONGER REINFORCING WAVE TOWARDS THE WEEKEND. CONSIDERABLE UNCERTAINTY EXISTS BEYOND THURSDAY GIVEN THE RATHER COMPLICATED UPSTREAM PATTERN. EITHER WAY...THE UPCOMING WORK WEEK DOES LOOK TO BE RATHER QUIET CONSIDERING THE TIME OF YEAR. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 415 AM CDT SAT APR 19 2008 .DISCUSSION... THE DEPARTURE OF THE STRATUS DECK OUT OF THE EASTERN TIER OF COUNTIES AND THEN CONVECTIVE POTENTIAL ON MONDAY AND MONDAY NIGHT ARE THE FOCUS OF THE FORECAST PACKAGE. WATER VAPOR IMAGERY INDICATES COLD CORE LOW CONTINUING SLOWLY OFF TO THE EAST. LAST REMNANTS OF MOISTURE WERE PUSHING SOUTH THROUGH THE EXTREME EASTERN PORTION OF THE CWA...GENERALLY OVER AREAS EAST OF HIGHWAY 75 AT 07Z. AT THE SURFACE...LOW PRESSURE WILL PUSH SLOWLY EAST WITH UPPER LEVEL SYSTEM THIS MORNING ALLOWING WEAK RIDGING TO BUILD IN ACROSS THE CWA TODAY. EXPECT STRATUS TO LINGER JUST WEST OF THE KS/MO BORDER AROUND SUNRISE...SO HAVE KEPT SOME CLOUD COVER IN AROUND 12Z FOR LAWRENCE AND OTTAWA TO START OFF THE DAY. 06Z RUC INDICATES THAT STRATUS WILL PUSH EAST OF THE CWA BY 15Z...SO FROM 15Z ON HAVE SKC CONDITIONS OVER THE FORECAST AREA. ASSUMING STRATUS HAS EXITED OFF TO THE EAST AS EXPECTED BY MID MORNING HIGHS WILL CLIMB INTO THE LOWER 70S ACROSS THE CWA...WITH SOME UPPER 60S POSSIBLE WHERE STRATUS LINGERS THIS MORNING. WINDS WILL BE GENERALLY LIGHT AND VARIABLE WITHIN THE RIDGE AXIS TODAY...AND WILL EVENTUALLY COME AROUND TO THE SOUTH AS LEE TROUGHING BEGINS TO DEVELOP OVER THE HIGH PLAINS SENDING SURFACE RIDGE EAST OF THE CWA THIS EVENING. SHORTWAVE RIDGING WILL PUSH EAST OVER THE PLAINS TONIGHT AS AN UPPER LEVEL TROUGH CURRENTLY OVER THE NORTHWESTERN CONUS BUILDS SOUTHEAST INTO THE INTERMOUNTAIN WEST. A SHORTWAVE EMBEDDED IN THIS LARGER TROUGH WILL AID IN THE STRENGTHENING OF THE LEE TROUGH ON SUNDAY BRINGING STRONGER SOUTHERLY WINDS AND WARMER WEATHER THROUGH THE CWA. HIGHS ON SUNDAY ARE EXPECTED TO CLIMB INTO THE UPPER 70S TO LOWER 80S. BY SUNDAY NIGHT MODELS INDICATE THAT PERSISTENT SOUTHERLY FLOW FINALLY TAPS INTO DEEPER GULF MOISTURE...AND RAPID LOW LEVEL MOISTURE TRANSPORT IS CONSISTENTLY FORECAST IN ALL GUIDANCE. ECMWF AND NAM WERE ABOUT 3-6 HOURS SLOWER WITH THE STRONGEST MOISTURE RETURN WHEN COMPARED TO THE GFS. GENERAL CONSENSUS WAS TO ADOPT THE SLIGHTLY SLOWER MOISTURE TRANSPORT AND ASSOCIATED STRATACUMULUS DECK...SO BACKED OFF ON CLOUD COVER AROUND 06Z MONDAY...AND THEN BROUGHT STRATUS RAPIDLY NORTH BY 12Z OVER THE ENTIRE FORECAST AREA. THE SHORTWAVE TROUGH WILL CONTINUE ROTATING THROUGH THE LARGER TROUGH AXIS OVER THE WESTERN CONUS...SENDING THE LEE TROUGH/COLD FRONT SOUTHEAST THROUGH THE NORTHERN PLAINS AND TOWARDS CENTRAL KS BY MONDAY MORNING. THE SHORTWAVE TROUGH EJECTS RAPIDLY NORTH INTO SOUTHERN CANADA BY MONDAY MORNING...SO WOULD EXPECT THE FRONT TO STALL OUT AT SOME POINT DURING THE DAY ON MONDAY...HOWEVER THE SPEED OF THE FRONT AND HOW FAR SOUTHEAST IT PROGRESSES BEFORE STALLING OUT REMAIN UNCERTAIN WITH PROGRESSIVE RUNS OF THE ECMWF ADVERTISING FASTER SOLUTIONS WHILE THE GFS OFFERS A SLOWER FRONTAL MOVEMENT SOLUTION. A SECONDARY SHORTWAVE TROUGH ROTATING THROUGH THE BASE OF THE LARGER TROUGH WILL BRING RENEWED PRESSURE FALLS OVER SOUTHEASTERN CO DURING THE DAY ON MONDAY WHICH WILL DEFINITELY STALL ANY POTENTIAL PROGRESS THE FRONT WAS MAKING...AND POTENTIALLY CAUSE IT TO RETROGRADE SOMEWHAT AS SURFACE LOW DEEPENS AND BEGINS TO MOVE NORTHEAST MONDAY AFTERNOON. SOUTH OF THE FRONT GULF MOISTURE AND BREAKS IN THE STRATUS DECK WILL DESTABILIZE THE ATMOSPHERE...SO THE EXACT POSITION OF THE FRONT IS VERY IMPORTANT FOR CONVECTIVE POTENTIAL MONDAY AFTERNOON. WITH 24 HOURS OF SOUTHWESTERLY MID LEVEL FLOW A STRONG EML WILL BE IN PLACE OVER THE FORECAST AREA...SO CONVECTION WILL LIKELY BE LOCATED NEAR THE CONVERGENCE AXIS ALONG THE FRONTAL BOUNDARY...AND WILL DEPEND ON THE PATH THE SHORTWAVE TROUGH TAKES AS IT EJECTS NORTHEAST INTO THE CENTRAL PLAINS MONDAY AFTERNOON. LARGELY DUE TO THE STRENGTH OF THE EML...HAVE KEPT POPS IN THE SLIGHT CHANCE CATEGORY MONDAY AFTERNOON WITH SEVERAL FACTORS NEEDING TO COME TOGETHER TO ENHANCE CONVECTIVE POTENTIAL. IF THUNDERSTORMS DO MANAGE TO DEVELOP MONDAY AFTERNOON OR EVENING...THERE IS A PRETTY GOOD CHANCE THE STORMS WOULD BE SEVERE WITH MLCAPE VALUES IN THE 1200-1800 J/KG RANGE...AND FAVORABLE HODOGRAPH/SHEAR PROFILES FOR SUPERCELLS IN THE WARM SECTOR RIGHT ALONG AND SOUTHEAST OF THE FRONTAL BOUNDARY. WITH SOMEWHAT LOW CONFIDENCE IN THE EML CAP BEING ERODED OR OVERCOME WILL HOLD OFF MENTIONING SVR WX IN THE HWO FOR NOW. MONDAY NIGHT...SLIGHTLY HIGHER CONFIDENCE IN PRECIPITATION AS SURFACE LOW PUSHES NORTHEAST THROUGH THE CWA AND FRONTAL BOUNDARY ONCE AGAIN SURGES SOUTHEAST. CONVERGENCE ALONG THE FRONT WILL BE GREATER MONDAY NIGHT...SO HAVE AT LEAST CHANCE WORDING IN THE FORECAST AT THIS TIME. BEHIND THE COLD FRONT AND SHORTWAVE TROUGH ON TUESDAY FEEL PRECIPITATION CHANCES WILL END QUICKLY AND HAVE BACKED OFF ON POPS...JUST MENTIONING RAIN SHOWERS FOR MOISTURE WRAPPED UP BEHIND THE LOW PRESSURE SYSTEM EXITING OFF TO THE NORTHEAST. REMOVED POPS TUESDAY NIGHT AND WEDNESDAY AS COLD FRONT LOOKS TO PUSH SOUTH AT LEAST INTO AR AND OK BEFORE STALLING OUT. NO CHANGES WERE MADE TO THE FORECAST BEYOND WEDNESDAY. CAVANAUGH && .AVIATION... STRATUS ON THE BACK SIDE OF SFC LOW OVER THE MID MS RIVER VALLEY IS SLOW TO EXIT TO THE EAST. HOWEVER STEADY PROPAGATION OF THE UPPER CLOSED LOW TO THE EAST WILL ALLOW SKIES TO EVENTUALLY CLEAR. THERE MAY BE SOME TEMPO CIGS AROUND 2 KFT THROUGH MID MORNING. OTHERWISE INCREASING SUBSIDENCE ON THE BACK SIDE OF THE UPPER SYSTEM WITH SHORTWAVE RIDGING MOVING OVERHEAD WILL PROVIDE P6SM SKC AND LIGHT WINDS FOR MOST OF THE DAY. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1140 AM MDT FRI APR 18 2008 .DISCUSSION... 238 AM MDT FRI APR 18 2008 MAIN FORECAST PROBLEMS WILL BE HOW FAST TO RAISE TEMPERATURES THROUGH SUNDAY AND FIRE WEATHER CONCERNS SUNDAY. MINOR INITIAL PROBLEM WILL BE EXTENT AND DURATION OF FOG AND STRATUS. SATELLITE SHOWING A COMPLICATED AND ACTIVE FLOW PATTERN FROM THE CENTRAL PACIFIC INTO THE WESTERN ATLANTIC. THE FLOW WAS SHOWING SOME AMPLITUDE...ESPECIALLY OVER THE EASTERN PACIFIC. OVERALL FLOW WAS NOT THAT PROGRESSIVE. SYSTEM THAT BROUGHT OUR WIDESPREAD PRECIPITATION YESTERDAY IS ALSO ONLY MAKING SLOW PROGRESS TO THE EAST. MODELS ARE HAVING A TERRIBLE TIME THROUGH 06Z WITH THE JET STRENGTH AND POSITION FROM NORTHERN MEXICO INTO EASTERN KANSAS AND WESTERN MISSOURI. MODELS DO NOT HAVE JET AXIS FAR ENOUGH NORTH/TOO FAR EAST AND ARE ALSO NOT ORIENTED MORE SOUTH TO NORTH AND TOO WEAK IN THIS AREA. IF WERE TO CHOOSE A MODEL PREFERENCE IN THIS AREA...WOULD HAVE TO GIVE THE EDGE TO THE NAM. MODELS WERE HAVING A HARD TIME WITH THE INITIAL CONDITIONS AND POSITION OF UPPER FEATURES THROUGH 06Z FROM ALONG THE PACIFIC NORTHWEST INTO CENTRAL CANADA. OVERALL WOULD SAY THAT THE NAM WAS DOING SLIGHTLY BETTER THAN THE GFS. UKMET/ECMWF WERE DOING SLIGHTLY BETTER THAN THE GFS ON 850 MB TEMPERATURES. MODELS WERE SIMILAR WITH SURFACE PATTERN. DUE TO INITIALIZATION PROBLEMS WITH THE MODELS AND VARIOUS SOLUTIONS... CONFIDENCE IS LOW IN ANY ONE SOLUTION. SO WILL USE A BLEND OF THE MODELS...AND TEND TO GO WITH A MORE AMPLIFIED AND LESS PROGRESSIVE SOLUTION. THIS WILL ALSO LEAD TO A DRIER AND WARMER SOLUTION. TODAY/TONIGHT...INITIAL MINOR PROBLEM WILL BE HOW MUCH IF ANY FOG AND STRATUS WILL BE AROUND. SOUNDINGS ALONG WITH RUC/NAM WOULD INDICATE THAT ANY FOG THAT IS AROUND AT 12Z WILL BE GONE QUICKLY. WILL MONITOR AS LONG AS POSSIBLE BEFORE MAKING A FINAL DECISION. BUT WILL PROBABLY HIT STRATUS AND FOG HARDEST IN THE EASTERN HALF THROUGH MID MORNING. NO MATTER WHAT AFTER 15Z...SHOULD SEE PLENTY OF SUN THROUGH THE DAY WITH SOME DOWNSLOPE WINDS AS THE UPPER RIDGE BUILDS IN. TEMPERATURE ANALYSIS WOULD INDICATE THAT WILL BE SEEING WARM AIR ADVECTION BEHIND OUR EXITING SYSTEM. ONLY TWEAKED TEMPERATURES AND TENDED TO WITH THE WARMER GUIDANCE. SATURDAY/SATURDAY NIGHT...ONCE AGAIN SOUNDINGS INDICATE THAT SHOULD SEE PLENTY OF SUN WITH MAIN JET TO THE SOUTH OF AREA. INCREASING GRADIENT AND PRESSURE FALLS AS A RESULT OF STRONG WESTERLY FLOW AT MOUNTAIN TOP LEVEL WILL CAUSE SURFACE WINDS TO INCREASE INTO THE BREEZY CATEGORY DURING THE DAY. WILL ONCE AGAIN WILL GO WITH THE WARMER GUIDANCE. SUNDAY/SUNDAY NIGHT...SOUNDINGS/MOISTURE PROGS WOULD INDICATE THAT THERE SHOULD BE PLENTY OF SUN. AREA IS ALSO IN SUBSIDENCE BETWEEN NORTHERN AND SOUTHERN JETS. MODELS SHOULD HAVE NO PROBLEM MIXING TO A SIGNIFICANT DEPTH. WHICH MEANS LOWER DEWPOINTS THAN CURRENTLY DEPICTED BY ANY MODEL. ALSO BELIEVE THIS WILL MEAN MORE WINDS THAN ANY MODEL SAYS AS WELL AS WARMER THAN ANY MODEL. THIS WILL LEAD TO THE NEED FOR A FIRE WEATHER HIGHLIGHT. HOWEVER...IT IS STILL A FEW DAYS AND HARD TO PIN DOWN ANY PARTICULAR AREA DUE TO UNCERTAINTY IN MODEL PERFORMANCE. BUT WOULD SAY THE WEST WILL HAVE THE BEST SHOT TO GET A RED FLAG WARNING. AT THIS TIME...WILL HIGHLIGHT THIS POTENTIAL IN THE FIRE WEATHER FORECAST AND HAZARDOUS WEATHER OUTLOOK. FOR SOME REASON...THE MAV IS SPITTING OUT SLIGHT CHANCE POPS IN SOME LOCATIONS DURING THE DAY. NAM/GFS POINT SOUNDINGS SAY AIR MASS IS WAY TOO DRY TO SUPPORT PRECIPITATION...AND WILL DISCOUNT THE MAV AND KEEP IT DRY. MONDAY AND TUESDAY...NO CHANGES MADE. THANKS TO ALL FOR COLLABORATION. BULLER && .AVIATION... 1135 AM MDT FRI APR 18 2008 FOR THE 18Z TAF...QUIET CONDITIONS THROUGH AT LEAST THE NEXT 24 HOURS WITH VFR CONDITIONS FIRMLY IN PLACE AT BOTH KGLD AND KMCK. MID/UPPER LEVEL RIDGE WILL CONTINUE TO BUILD INTO THE CWA ALLOWING FOR WINDS GENERALLY LESS THAN 12 KTS. MAY HAVE A FEW GUSTS TO NEAR 20 KTS THIS AFTERNOON BEFORE WINDS BECOME VARIABLE AFTER AROUND 00Z. FOLTZ && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ WFO GOODLAND ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 232 AM MDT FRI APR 18 2008 .DISCUSSION... 232 AM MDT FRI APR 18 2008 MAIN FORECAST PROBLEMS WILL BE HOW FAST TO RAISE TEMPERATURES THROUGH SUNDAY AND FIRE WEATHER CONCERNS SUNDAY. MINOR INITIAL PROBLEM WILL BE EXTENT AND DURATION OF FOG AND STRATUS. SATELLITE SHOWING A COMPLICATED AND ACTIVE FLOW PATTERN FROM THE CENTRAL PACIFIC INTO THE WESTERN ATLANTIC. THE FLOW WAS SHOWING SOME AMPLITUDE...ESPECIALLY OVER THE EASTERN PACIFIC. OVERALL FLOW WAS NOT THAT PROGRESSIVE. SYSTEM THAT BROUGHT OUR WIDESPREAD PRECIPITATION YESTERDAY IS ALSO ONLY MAKING SLOW PROGRESS TO THE EAST. MODELS ARE HAVING A TERRIBLE TIME THROUGH 06Z WITH THE JET STRENGTH AND POSITION FROM NORTHERN MEXICO INTO EASTERN KANSAS AND WESTERN MISSOURI. MODELS DO NOT HAVE FAR ENOUGH NORTH/TOO FAR EAST AND ARE ALSO NOT ORIENTED MORE SOUTH TO NORTH AND TOO WEAK IN THIS AREA. IF WERE TO CHOOSE A MODEL PREFERENCE IN THIS AREA...WOULD HAVE TO GIVE THE EDGE TO THE NAM. MODELS WERE HAVING A HARD TIME WITH THE INITIAL CONDITIONS AND POSITION OF UPPER FEATURES THROUGH 06Z FROM ALONG THE PACIFIC NORTHWEST INTO CENTRAL CANADA. OVERALL WOULD SAY THAT THE NAM WAS DOING SLIGHTLY BETTER THAN THE GFS. UKMET/ECMWF WERE DOING SLIGHTLY BETTER THAN THE GFS ON 850 MB TEMPERATURES. MODELS WERE SIMILAR WITH SURFACE PATTERN. DUE TO INITIALIZATION PROBLEMS WITH THE MODELS AND VARIOUS SOLUTIONS... CONFIDENCE IS LOW IN ANY ONE SOLUTION. SO WILL USE A BLEND OF THE MODELS...AND TEND TO GO WITH A MORE AMPLIFIED AND LESS PROGRESSIVE SOLUTION. THIS WILL ALSO LEAD TO A DRIER AND WARMER SOLUTION. TODAY/TONIGHT...INITIAL MINOR PROBLEM WILL BE HOW MUCH IF ANY FOG AND STRATUS WILL BE AROUND. SOUNDINGS ALONG WITH RUC/NAM WOULD INDICATE THAT ANY FOG THAT IS AROUND AT 12Z WILL BE GONE QUICKLY. WILL MONITOR AS LONG AS POSSIBLE BEFORE MAKING A FINAL DECISION. WILL HIT STRATUS AND FOG HARDEST IN THE EASTERN HALF THROUGH MID MORNING. NO MATTER WHAT...SHOULD SEE PLENTY OF SUN THROUGH THE DAY WITH SOME DOWNSLOPE WINDS AS THE UPPER RIDGE BUILDS IN. TEMPERATURE ANALYSIS WOULD INDICATE THAT WILL BE SEEING WARM AIR ADVECTION BEHIND OUR EXITING SYSTEM. ONLY TWEEKED TEMPERATURES AND TENDED TO WITH COOLER GUIDANCE. SATURDAY/SATURDAY NIGHT...ONCE AGAIN SOUNDINGS INDICATE THAT SHOULD SEE PLENTY OF SUN WITH MAIN JET TO THE SOUTH OF AREA. INCREASING GRADIENT AND PRESSURE FALLS AS A RESULT OF STRONG WESTERLY FLOW AT MOUNTAIN WILL CAUSE WINDS TO INCREASE INTO THE BREEZY CATEGORY DURING THE DAY. WILL ONCE AGAIN WILL GO WITH THE WARMER GUIDANCE. SUNDAY/SUNDAY NIGHT...SOUNDINGS/MOISTURE PROGS WOULD INDICATE THAT THERE SHOULD BE PLENTY OF SUN. AREA IS ALSO IN SUBSIDENCE BETWEEN NORTHERN AND SOUTHERN JETS. MODELS SHOULD HAVE NO PROBLEM MIXING TO A SIGNIFICANT DEPTH. WHICH MEANS LOWER DEWPOINTS THAN CURRENT DEPICTED BY ANY MODEL. ALSO BELIEVE THIS WILL MEAN MORE WINDS THAN ANY MODEL SAYS AS WELL AS WARMER. THIS WILL LEAD TO THE NEED FOR A FIRE WEATHER HIGHLIGHT. HOWEVER...HARD TO PIN DOWN ANY PARTICULAR AREA BUT WOULD SAY THE WEST WILL HAVE THE BEST SHOT TO GET A RED FLAG WARNING. WILL HIGHLIGHT THIS POTENTIAL IN THE FIRE WEATHER FORECAST AND HAZARDOUS WEATHER OUTLOOK. FOR SOME REASON...THE MAV IS SPITTING OUT SLIGHT CHANCE POPS IN SOME LOCATIONS DURING THE DAY. NAM/GFS POINT SOUNDINGS SAY AIR MASS IS WAY TOO DRY TO SUPPORT PRECIPITATION...AND DISCOUNT THE MAV AND KEEP DRY. MONDAY AND TUESDAY...NO CHANGES MADE. THANKS TO ALL FOR COLLABORATION. BULLER && .AVIATION... 1230 AM MDT FRI APR 18 2008 FOR THE 06Z TAF CYCLE...A VERY NARROW BAND OF DENSE FOG HAS LINED UP ALONG THE FAR WESTERN EDGE OF NORTHWESTERN KANSAS...BRINGING KGLD DOWN INTO LIFR CONDITIONS WHILE KMCK REMAINS IN VFR CONDITIONS. BY ABOUT 11Z...KGLD IS EXPECTED TO RAPIDLY SCATTER OUT TO VFR CONDITIONS AS WINDS ORGANIZE AND SETTLE IN FROM THE WEST THROUGHOUT THE ENTIRE REGION. BLM && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ WFO GOODLAND ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 950 PM CDT SAT APR 19 2008 .UPDATE... SATELLITE TRENDS INDICATE CLEARING WILL BE SLOW TO OCCUR OVERNIGHT...ESPECIALLY IN SOUTHERN ILLINOIS AND MUCH OF WESTERN KY. RAISED LOW TEMPS SLIGHTLY IN THOSE AREAS. OVER SW INDIANA...POCKETS OF CLEARING OCCURRED SURPRISINGLY CLOSE TO THE UPPER LOW. EXPECT CLOUDS TO REDEVELOP FROM THE WEST OR NORTHWEST ACROSS SW INDIANA. ADDED MENTION OF PATCHY FOG OVER PARTS OF SE MISSOURI...WHERE SKIES WILL REMAIN CLEAR OVERNIGHT. WINDS ALREADY WENT CALM IN MOST AREAS. REPLACED ISOLATED SHOWER WORDING WITH CHANCE OF SPRINKLES BASED ON RADAR TRENDS. && .PREVIOUS DISCUSSION /ISSUED 130 PM CDT SAT APR 19 2008/... SHORT TERM... /TONIGHT THROUGH TUESDAY NIGHT/ LATEST SURFACE ANALYSIS SHOWS LOW OVER CENTRAL IL WITH THE 12Z 500 MB LOW NEARLY VERTICALLY STACKED. A COLD FRONT EXTENDED FROM THE LOW TO THE SOUTHEAST OVER EASTERN KY...WITH AN ASSOCIATED TROF APPROACHING THE MISSISSIPPI RIVER. REG RADAR LOOP SHOWS SCATTERED LIGHT SHOWERS ROTATING AROUND THE LOW...ACROSS THE MOST OF THE FA. VIS SAT LOOP INDICATES SOME EASTWARD PROGRESS OF THE LOWS WITH THE TRAILING EDGE OF THE CLOUDS ALONG A LINE FROM THE BOOTHEEL THROUGH SGF TO KC. LDS CHART SHOWS NO CLOUD TO GROUND STRIKES OVER THE ENTIRE REGIONAL VIEW. BOTH THE 00Z AND 12Z SAT RUN OF THE NAM SHOW PRECIP OUT OF FA BY 00Z SUN. THE 14Z RUN OF THE RUC ALSO SUGGESTS A SIMILAR SCENARIO. THE 12Z SAT RUN OF THE GFS...INDICATES A FEW HUNDREDTHS IN THE EVV TO HOP CORRIDOR AS DOES THE 12Z SAT ECMWF...WITH THIS IN MIND WILL KEEP AT LEAST A SMALL CHANCE IN EXTREME EAST AFTER 00Z SUN AND MONITOR LATEST RADAR LOOP FOR EXACT CUTOFF LOCATION OF POPS...CLOSER TO PRESS TIME OF COURSE. WILL KEEP THINGS DRY SUNDAY AND MONDAY AS MODEL CONSENSUS IS ADVERTISING FOR THE MOST PART. THE LATEST 12Z MODEL RUNS ALSO SUGGEST THAT ANY PRECIP MONDAY NIGHT WOULD LIKELY BE LATE AND CONFINED TO THE WESTERN HALF SO HAVE ADJUSTED GRIDS TO REFLECT THE AFOREMENTIONED. ALTHOUGH THE MODELS ARE IN PRETTY GOOD AGREEMENT OF BRINGING NEG SFC LI`S TO THE REGION MONDAY NIGHT THE BEST MOISTURE DOES NOT ARRIVE TIL LATE AND MAINLY OVER THE WEST. SO HAVE LEFT POPS IN ALL NIGHT BUT TWEAKED THE COVERAGE TO THE WEST HALF. ATMOSPHERE REMAINS UNSTABLE THROUGH TUESDAY NIGHT SO WILL MAINTAIN THUNDER. CAPE VALUES SOAR INTO THE 2000 J/KG DURING THE DAY TUESDAY SO THAT WILL BE THE BEST CHANCE OF THUNDER COVERAGE. ALTHOUGH CAPE DROPS OFF A GREAT DEAL TUESDAY NIGHT BUT STILL REMAINS IN THE 200 J/KG WITH NEG LI`S. THIS COMBINED WITH FRONT BISECTING THE ARE...WILL ALSO CONTINUE THUNDER. IN ADDITION IF THE 12Z GFS CAPES ARE CORRECT MIGHT BE A CHANCE OF ACTIVE WEATHER TUESDAY...WILL MONITOR FOR SUCCESSIVE MODEL RUNS FOR POSSIBLE STRONG THUNDERSTORMS TUESDAY INTO TUESDAY EVENING. AS FOR SKY COVER BEGAN CLEARING LATE TODAY OVER SEMO AND SLOWLY SPREAD CLEARING EASTWARD TO THE EVV AREA AROUND SUNRISE SUNDAY. AS FOR TEMPS ONLY MINOR TWEAKS TO REFLECT LATEST GUIDANCE TRENDS. LONG TERM... /WEDNESDAY THROUGH SATURDAY/ IN THE MEDIUM RANGE PERIOD...THE 00Z ECMWF AND ITS ENSEMBLE MEAN ARE FAVORED BY HPC AND WILL BE FOLLOWED CLOSELY FOR THIS FORECAST. THIS RESULTS IN SOME SIGNIFICANT DEVIATIONS FROM THE 06Z AND 12Z GFS. THE GFS SOLUTION IS MUCH MORE PROGRESSIVE IN GENERAL...ADVERTISING COLD FRONT PASSAGES EARLY WEDNESDAY AND EARLY FRIDAY. A PATTERN SHIFT TO MORE OF A WESTERN TROUGH/EASTERN RIDGE REGIME IS FAVORED...WHICH LEADS TO A LESS ROBUST FRONTAL PASSAGE WEDNESDAY...AND A SLOWER ARRIVAL TO THE NEXT FRONT NOW FORECAST FOR LATE SATURDAY. FOLLOWING THE ECMWF SOLUTION RESULTS IN 20-30 POPS THROUGHOUT THE PERIOD WEDNESDAY THROUGH SATURDAY. IN GENERAL...HAVE 30S WITH THE WARM FRONT THURSDAY AND THE COLD FRONT SATURDAY...AND 20S WHEN WE ARE IN THE WARM SECTOR THURSDAY NIGHT THROUGH EARLY SATURDAY. WITH THE MID/UPPER LEVEL RIDGING THROUGH THE REGION...TEMPERATURES WILL REMAIN MILD THROUGH THE PERIOD. HIGHS WILL GENERALLY BE IN THE 70S WITH LOWS IN THE 50S EACH DAY. && .AVIATION... MVFR CONDITIONS IN SCATTERED SHOWERS WILL PERSIST FOR MUCH OF THE AFTERNOON...MAINLY ACROSS SOUTHERN ILLINOIS AND THE EVANSVILLE TRI STATE AREA. SKIES SHOULD CLEAR OUT OVER THE SOUTHWEST HALF OF THE AREA EARLY THIS EVENING...AND AS WINDS GO CALM...FOG DEVELOPMENT WILL BE LIKELY...WITH SOME AREAS LIKE KCGI POSSIBLY BECOMING LOCALLY DENSE. IN THE KEVV AND KOWB AREAS...MVFR TO LOW VFR CEILINGS ARE EXPECTED TO CONTINUE THROUGHOUT THE 18Z TAF PERIOD. THERE WILL BE A BREAK IN THE SHOWERY PRECIPITATION FROM LATE AFTERNOON TO LATE EVENING...BUT ANOTHER ROUND OF SHOWERS WITH MVFR CONDITIONS WILL BE POSSIBLE FROM 06Z-15Z. IN THE NORTHEAST...WINDS WILL WAFFLE 20-30 DEGREES OR SO EITHER SIDE OF DUE WEST THROUGHOUT THE PERIOD. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREVIOUS...KH/DS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 130 PM CDT SAT APR 19 2008 .SHORT TERM... /TONIGHT THROUGH TUESDAY NIGHT/ LATEST SURFACE ANALYSIS SHOWS LOW OVER CENTRAL IL WITH THE 12Z 500 MB LOW NEARLY VERTICALLY STACKED. A COLD FRONT EXTENDED FROM THE LOW TO THE SOUTHEAST OVER EASTERN KY...WITH AN ASSOCIATED TROF APPROACHING THE MISSISSIPPI RIVER. REG RADAR LOOP SHOWS SCATTERED LIGHT SHOWERS ROTATING AROUND THE LOW...ACROSS THE MOST OF THE FA. VIS SAT LOOP INDICATES SOME EASTWARD PROGRESS OF THE LOWS WITH THE TRAILING EDGE OF THE CLOUDS ALONG A LINE FROM THE BOOTHEEL THROUGH SGF TO KC. LDS CHART SHOWS NO CLOUD TO GROUND STRIKES OVER THE ENTIRE REGIONAL VIEW. BOTH THE 00Z AND 12Z SAT RUN OF THE NAM SHOW PRECIP OUT OF FA BY 00Z SUN. THE 14Z RUN OF THE RUC ALSO SUGGESTS A SIMILAR SCENARIO. THE 12Z SAT RUN OF THE GFS...INDICATES A FEW HUNDREDTHS IN THE EVV TO HOP CORRIDOR AS DOES THE 12Z SAT ECMWF...WITH THIS IN MIND WILL KEEP AT LEAST A SMALL CHANCE IN EXTREME EAST AFTER 00Z SUN AND MONITOR LATEST RADAR LOOP FOR EXACT CUTOFF LOCATION OF POPS...CLOSER TO PRESS TIME OF COURSE. WILL KEEP THINGS DRY SUNDAY AND MONDAY AS MODEL CONSENSUS IS ADVERTISING FOR THE MOST PART. THE LATEST 12Z MODEL RUNS ALSO SUGGEST THAT ANY PRECIP MONDAY NIGHT WOULD LIKELY BE LATE AND CONFINED TO THE WESTERN HALF SO HAVE ADJUSTED GRIDS TO REFLECT THE AFOREMENTIONED. ALTHOUGH THE MODELS ARE IN PRETTY GOOD AGREEMENT OF BRINGING NEG SFC LI`S TO THE REGION MONDAY NIGHT THE BEST MOISTURE DOES NOT ARRIVE TIL LATE AND MAINLY OVER THE WEST. SO HAVE LEFT POPS IN ALL NIGHT BUT TWEAKED THE COVERAGE TO THE WEST HALF. ATMOSPHERE REMAINS UNSTABLE THROUGH TUESDAY NIGHT SO WILL MAINTAIN THUNDER. CAPE VALUES SOAR INTO THE 2000 J/KG DURING THE DAY TUESDAY SO THAT WILL BE THE BEST CHANCE OF THUNDER COVERAGE. ALTHOUGH CAPE DROPS OFF A GREAT DEAL TUESDAY NIGHT BUT STILL REMAINS IN THE 200 J/KG WITH NEG LI`S. THIS COMBINED WITH FRONT BISECTING THE ARE...WILL ALSO CONTINUE THUNDER. IN ADDITION IF THE 12Z GFS CAPES ARE CORRECT MIGHT BE A CHANCE OF ACTIVE WEATHER TUESDAY...WILL MONITOR FOR SUCCESSIVE MODEL RUNS FOR POSSIBLE STRONG THUNDERSTORMS TUESDAY INTO TUESDAY EVENING. AS FOR SKY COVER BEGAN CLEARING LATE TODAY OVER SEMO AND SLOWLY SPREAD CLEARING EASTWARD TO THE EVV AREA AROUND SUNRISE SUNDAY. AS FOR TEMPS ONLY MINOR TWEAKS TO REFLECT LATEST GUIDANCE TRENDS. .LONG TERM... /WEDNESDAY THROUGH SATURDAY/ IN THE MEDIUM RANGE PERIOD...THE 00Z ECMWF AND ITS ENSEMBLE MEAN ARE FAVORED BY HPC AND WILL BE FOLLOWED CLOSELY FOR THIS FORECAST. THIS RESULTS IN SOME SIGNIFICANT DEVIATIONS FROM THE 06Z AND 12Z GFS. THE GFS SOLUTION IS MUCH MORE PROGRESSIVE IN GENERAL...ADVERTISING COLD FRONT PASSAGES EARLY WEDNESDAY AND EARLY FRIDAY. A PATTERN SHIFT TO MORE OF A WESTERN TROUGH/EASTERN RIDGE REGIME IS FAVORED...WHICH LEADS TO A LESS ROBUST FRONTAL PASSAGE WEDNESDAY...AND A SLOWER ARRIVAL TO THE NEXT FRONT NOW FORECAST FOR LATE SATURDAY. FOLLOWING THE ECMWF SOLUTION RESULTS IN 20-30 POPS THROUGHOUT THE PERIOD WEDNESDAY THROUGH SATURDAY. IN GENERAL...HAVE 30S WITH THE WARM FRONT THURSDAY AND THE COLD FRONT SATURDAY...AND 20S WHEN WE ARE IN THE WARM SECTOR THURSDAY NIGHT THROUGH EARLY SATURDAY. WITH THE MID/UPPER LEVEL RIDGING THROUGH THE REGION...TEMPERATURES WILL REMAIN MILD THROUGH THE PERIOD. HIGHS WILL GENERALLY BE IN THE 70S WITH LOWS IN THE 50S EACH DAY. && .AVIATION... MVFR CONDITIONS IN SCATTERED SHOWERS WILL PERSIST FOR MUCH OF THE AFTERNOON...MAINLY ACROSS SOUTHERN ILLINOIS AND THE EVANSVILLE TRI STATE AREA. SKIES SHOULD CLEAR OUT OVER THE SOUTHWEST HALF OF THE AREA EARLY THIS EVENING...AND AS WINDS GO CALM...FOG DEVELOPMENT WILL BE LIKELY...WITH SOME AREAS LIKE KCGI POSSIBLY BECOMING LOCALLY DENSE. IN THE KEVV AND KOWB AREAS...MVFR TO LOW VFR CEILINGS ARE EXPECTED TO CONTINUE THROUGHOUT THE 18Z TAF PERIOD. THERE WILL BE A BREAK IN THE SHOWERY PRECIPITATION FROM LATE AFTERNOON TO LATE EVENING...BUT ANOTHER ROUND OF SHOWERS WITH MVFR CONDITIONS WILL BE POSSIBLE FROM 06Z-15Z. IN THE NORTHEAST...WINDS WILL WAFFLE 20-30 DEGREES OR SO EITHER SIDE OF DUE WEST THROUGHOUT THE PERIOD. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ KH/DS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 920 PM EDT SAT APR 19 2008 .UPDATE...UPPER LOW SPINNING AWAY IN THE OHIO VALLEY...WITH A LESS WELL-DEFINED SURFACE LOW IN THE SOUTHERN LAKES. WE REMAIN TOO FAR NORTH TO HAVE MUCH OF A PRECIP THREAT. EARLIER (ABOUT 530PM)...THE LAKE MI LAKE BREEZE COLLIDED WITH A WELL-DEFINED HORIZONTAL ROLL... SPITTING OUT A SINGLE SHOWER THAT BROUGHT SOME RAINDROPS TO ACME AND MAPLETON. A MORE SUBSTANTIAL AREA OF SHOWERS BLOSSOMED IN W CENTRAL LOWER JUST AFTER THAT...WHERE SURFACE DEW POINTS WERE IN THE 40S (VS THE 30S UP HERE). THESE SHOWERS GRAZED THE MBL AREA. OTHERWISE...MID AND HIGH CLOUDS AND HAZY SKIES ARE THE RULE. GRIDS WERE UPDATED FOR AN ISOLATED SHOWER OR TWO IN THE SW ZONES THRU 02Z/10PM. WITH LOSS OF HEATING...THE REST OF THE NIGHT WILL BE DRY. WILL LOWER MIN TEMPS AT SOME COASTAL LOCATIONS...WHERE LAKE BREEZES HAVE GIVEN THEM A HEAD START IN COOLING OFF. ZOLTOWSKI && .AVIATION...ISSUED 710 PM SAT APR 19... LOW PRESSURE WILL STEADILY MOVE EAST ACROSS THE OHIO VALLEY. FAIR AMOUNT OF MID/HIGH CLOUDS AND HAZE ALOFT...BUT SHOWERS WILL STAY SOUTH OF ALL TAF SITES. WEATHER WILL REMAIN WARM...WITH LAKE BREEZES DEVELOPING AGAIN SUNDAY AFTERNOON AGAINST A BACKDROP OF OTHERWISE LIGHT EASTERLY WINDS. VFR THRU THE FORECAST. JZ && .PREV DISCUSSION...ISSUED 303 PM SAT APR 19... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LEVEL LOW SPINNING OVER THE SOUTHERN IL-IN BORDER AND A BROAD AREA OF SURFACE LOW PRESSURE OVER THE SOUTHERN GREAT LAKES. BANDS OF MID AND UPPER LEVEL CLOUD COVER CONTINUE TO ROTATE ACROSS NORTHERN MICHIGAN WITH HOLES IN THE CIRRUS SHIELD APPEARING EVERY NOW AND THEN. THESE CLOUDS HAVE NOT PREVENTED TEMPERATURES FROM RAPIDLY WARMING INTO THE LOW TO MID 70S INLAND. WITH PRECIP WELL TO THE SOUTH OVER FAR SOUTHERN LOWER MICHIGAN...MAIN FORECAST CONCERNS INCLUDE TEMPS AND SKY COVER TONIGHT...THEN SMALL CHANCES OF PRECIP ALONG LAKE BREEZE BOUNDARIES TOMORROW. TONIGHT...UPPER LOW WILL DRIFT SLIGHTLY SOUTH OF EAST AS IT CUTS ACROSS THE OHIO RIVER VALLEY TO THE CENTRAL APPALACHIANS. SPOKE OF UPPER LEVEL MOISTURE WILL PINWHEEL ACROSS NORTHERN MICHIGAN TONIGHT...BUT FORCING AND DEEP MOISTURE WILL REMAIN WELL SOUTH OF THE REGION. THAT LEAVES TEMPERATURES AND SKY COVER TO THINK ABOUT. LOWS LAST NIGHT DIPPED INTO THE MIDDLE AND UPPER 30S ACROSS NE LOWER WHERE CLEAR SKIES HUNG ON THE LONGEST. DO NOT THINK THAT WILL HAPPEN TONIGHT DUE TO THE CIRRUS SHIELD...EVEN THOUGH THIS CIRRUS WILL THIN OVERNIGHT ACROSS NORTHERN LOWER. SO HAVE KEPT LOWS SIMILAR TO LAST NIGHT EXCEPT RAISED THEM A FEW DEGREES OVER NE LOWER. LOWS IN THE 40S. TOMORROW...UPPER LOW WILL MEANDER ACROSS THE CENTRAL APPALACHIANS WHILE MID-LEVEL HEIGHTS SLOWLY BUILD ACROSS THE NORTHERN GREAT LAKES. NO LARGE-SCALE FORCING TO SPEAK UP WITH THE BUILDING RIDGE...BUT STILL HINTS THAT LOCALIZED CONVERGENCE WILL SETUP ACROSS THE SW CWA WITH PREVAILING EAST FLOW BUTTING HEADS AGAINST LAKE BREEZES OFF OF LAKE MICHIGAN AND GRAND TRAVERSE BAY. BOTH NAM/GFS SPIT OUT QPF CENTERED AROUND WEXFORD COUNTY...BUT THINK THIS IS MORE OF A BY-PRODUCT OF OVER-GENEROUS SURFACE DEWPOINTS...WHICH BOTH MODELS SHOW IN THE LOWER TO MID 50S. DEEP MIXING UP TO 775MB SUGGESTS DEWPOINTS WILL MIX OUT TO AROUND 48F. USING A TEMP OF 72F...THIS WOULD YIELD SKINNY ML CAPES AROUND 200 J/KG IN THE MORE MOIST NAM SOLUTION...WHILE THE DRIER GFS SUGGESTS TOO MUCH CIN WILL EXIST TO TRIGGER A SHOWER. GIVEN THE INCREASING SUBSIDENCE THROUGH THE DAY...LEAN MORE TOWARD THE DRIER SOLUTION AND WILL LEAVE POPS OUT OF THE FORECAST. ANOTHER WARM DAY ON TAP WITH HIGHS RANGING FROM THE MID 60S NORTH/NEAR LAKESHORES...TO THE LOWER 70S INLAND. MPC SUN NIGHT THRU MON NIGHT...RATHER QUIET PERIOD OF WX EXPECTED TO CONTINUE...THOUGH A FEW FCST CONCERNS REMAIN...NAMELY TEMPS MON AFTN ALONG WITH ANY SMALL PRECIP CHANCES THRU THE PERIOD. POTENT CLOSED LOW SPINNING OVR SOUTHERN IN THIS AFTN PROGGED TO SLIP INTO VIRGINIA BY EARLY MON...WITH BROAD SHORTWAVE RIDGING BUILDING ACRS THE LAKES IN ADVANCE OF NEXT UPSTREAM TROUGH OVR THE NORTHWEST. HOWEVER... CONCERN REGARDING POTENTIAL PRECIP STEMS FROM BROAD PLUME OF WRAP AROUND MOISTURE PROGGED TO ADVECT BACK INTO THE REGION SUN NIGHT TIMEFRAME...AS UPR GYRE ABLE TO TAP ADDITIONAL MOISTURE FROM THE ATLANTIC. INTERESTING TO NOTE BOTH NAM AND GFS SPIT OUT A HINT OF MEASURABLE PRECIP SUN NIGHT/EARLY MON THOUGH DIFFICULT TO FORESEE THIS GIVEN OVERALL LACK OF MID/UPR LEVEL MOISTURE AND FORCING...WITH ONLY SOME WEAK HINT OF CHANNELED VORT (REMNANTS OF CLOSED LOW TO THE SOUTH TODAY) HEADING NORTH THRU THE NIGHT. THUS WILL MAINTAIN DRY FCST AT THIS TIME. HEADING INTO MON AFTN...APPEARS ANOTHER WARM DAY ON TAP WITH DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING UPR TROUGH...THOUGH OVERALL LACK OF MIXING PER LOW LEVEL RIDGE AXIS DRAPED OVERHEAD SHOULD KNOCK A FEW DEGREE OFF POTENTIAL HIGHS (READINGS MAINLY MID/UPR 60S LOOK GOOD). DESPITE GOOD HEATING AND LIKELY LAKE BREEZE CONVERGENCE ALONG THE LAKE MICHIGAN SIDE... DIFFICULT TO SEE CONVECTION (OTHER THAN A FAIRLY HEALTHY CU FIELD) FIRING DESPITE AN INCREASE IN BOUNDARY LAYER MOISTURE...AS MID LEVEL SUBSIDENCE INVERSION BUILDS THRU THE DAY. LATER PERIODS (TUE THRU SAT)...PATTERN TO REMAIN QUITE BLOCKY THRU THE EXTENDED PORTION OF THE FCST...OWING TO HIGHLY AMPLIFIED/ CLOSED MID LEVEL RIDGE ACRS CENTRAL/EASTERN ALASKA...IMPLYING SIGNIFICANT DOWNSTREAM TROUGHING INTO THE WESTERN CONUS. INDEED... THIS TYPE OF PATTERN IS WHAT THE MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST...WITH INITIAL CLOSED LOW (EVIDENT THIS AFTN NEAR THE BRITISH COLUMBIA/WASHINGTON STATE BORDER) AND ASSOCIATED ENERGY SHEARING OUT INTO THE NORTHERN PLAINS/UPR MIDWEST ON TUE...OWING TO BRIEF DISRUPTION OF BLOCKING FLOW ACRS THE EASTERN PACIFIC AS ENERGY UNDERCUTS THE RIDGE. END RESULT FOR NORTHERN MI WILL BE INCREASING CHANCES FOR PRECIP TUE NIGHT AS ASSOCIATED SFC FRONT AND WEAKENING FORCING SLIDES THRU THE REGION. WILL CONTINUE THUNDER MENTION AS WELL WITH EXPECTED DECENT MOISTURE TAP INTO THE AREA VIA OPEN GULF...AND MODEL PROGS OF SHOWALTER INDICES DIPPING WELL BELOW 0C ALONG WITH STEEPER MID LEVEL LAPSE RATE PLUME OVERHEAD. PONDERED BRINGING SMALL POPS BACK INTO THE PICTURE FOR TUE AFTN AS MOISTURE INCREASES AHEAD OF THE FRONT...WITH POTENTIAL FOR BRIEF CONVECTION TO POP AHEAD OF THE BOUNDARY GIVEN EXPECTED HEATING AND LIKELY LOW LEVEL WEAK UPSLOPE REGIME INTO THE HIGHER TERRAIN PER BACKING OF FLOW AHEAD OF THE FRONT...THOUGH ANYTHING ISOLATED AT BEST SO DRY FCST WILL CONTINUE. TEMPS TUE IFFY PENDING DEGREE OF SUN...THOUGH POTENTIAL IS THERE FOR A VERY WARM DAY WITH REGION IN THE THERMAL RIDGE AHEAD OF THE FRONT. WILL RUN WITH MID 60S TO LOWER 70S AREAWIDE. STILL LOOKS LIKE A DRY AND MORE SEASONABLE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGING AND ASSOCIATED SUBSIDENCE/DRYING TAKE HOLD. 00Z GUIDANCE NUMBERS APPEAR A BIT TOO COOL GIVEN EXPECTED SUN...SO WILL RUN WITH TEMPS UPR 50S TO MID 60S. THEREAFTER...GUIDANCE BEGINS TO DIVERGE ON AMPLITUDE OF ADDITIONAL WESTERN TROUGHING THU/FRI...THOUGH PATTERN RECOGNITION WITH DEEP LAYER/MERIDIONAL RIDGE BECOMING RE-ESTABLISHED ACRS ALASKA CERTAINLY ARGUES FOR THE ECMWF/GEFS MEAN SOLUTIONS OF A DEEPER WESTERN TROUGH. REGARDLESS OF EVENTUAL SOLUTION...IMPLICATION FOR THE CWA IS ADDITIONAL PRECIP CHANCES FRI/SAT TIMEFRAME AS LEE CYCLOGENESIS GETS GOING ON THE PLAINS...WITH ASSOCIATED COLD FRONT HEADING EAST BY THE WEEKEND. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 738 PM EDT SAT APR 19 2008 UPDATED AVIATION DISCUSSION FOR 00Z TAFS .SYNOPSIS (ISSUED AT 350 PM EDT)... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF ALG THE W COAST AND BLDG RDG OVER THE E HALF OF NAMERICA. CUTOFF LO UNDER THE BLDG RDG IS MOVING E THRU THE OH VALLEY WHILE ANOTHER SHRTWV IS LIFTING INTO WRN LK SUP. INTERACTION OF THIS SHRTWV/ ASSOCIATED UPR DVGC/DPVA/H85-5 QVECTOR CNVGC WITH DEEPER MSTR SHOWN ON THE 12Z MPX RAOB IS CAUSING SCT -SHRA/QUITE A BIT OF LO CLD OVER THE NW HALF OF THE FA EARLY THIS AFTN. BUT 12Z GRB/APX RAOBS SHOW MUCH DRIER AIR IS PRESENT TO THE SE ABV LINGERING SHALLOW MSTR. WITH SE H85 WINDS BTWN CUTOFF LO IN THE OH VALLEY AND HUDSON BAY HI PRES...THIS DRY IS OVERSPRDG THE FA...HAS ENDED THE PCPN OVER THE SCNTRL AND E...AND IS TENDING TO DIMINISH THE SHRA COVG OVER THE NW. .SHORT TERM (TONIGHT AND SUNDAY ISSUED AT 350 PM EDT)... FOR TNGT...GENERAL MSLP/UPR HGT RISES FCST OVER THE UPR LKS DOWNSTREAM OF DEEPENING TROF IN THE W. WITH PERSISTENT ELY FLOW BTWN HUDSON BAY HI AND DEPARTING CLOSED LO IN THE OH VALLEY...EXPECT DRIER AIR IN THAT DIRECTION TO CONTINUE MAKING INROADS ESE-WNW THRU THE FA. WL RESTRICT MENTION OF POPS THIS EVNG TO THE W BEFORE DROPPING MENTION OF PCPN EXCEPT OVER WRN LK SUP UNDER LINGERING DEEPER MSTR CLOSER TO INCRSGLY SHEARED SHRTWV IMPACTING THAT AREA. EVEN THOUGH THE MID LVLS WL BE DRYING OUT...SUSPECT THE LLVL MSTR WL BE HARDER TO DISLODGE. THIS LLVL MSTR WL BE MOST RESILIENT OVER THE NW IN AREAS WHERE LO CLDS HAVE LINGERED THRU THE DAY AND LIMITED INSOLATION/MIXING. SO WL FCST AREAS OF FOG TO DVLP DESPITE SOME LINGERING HI CLD. HOWEVER...CONDITIONS DON`T APPEAR IDEAL FOR DENSE FOG FORMATION WITH FCST RELATIVELY SHARP PRES GRADIENT BTWN HI TO THE N AND LO IN THE OH VALLEY. EXPECT ONLY PTCHY FOG OVER THE E CONSIDERING THE DEEPER MIXING EVIDENT THERE THIS AFTN. WL TEND TO UNDERCUT MOS FCST LO TEMPS OVER THE INTERIOR E CLOSER TO THE CORE OF THE DRIEST AIR. ON SUN...ACYC ENE FLOW WL DOMINATE THE UPR GRT LKS. WITH DRY AIR ABV THE SFC IN THE MRNG...INSOLATION SHOULD MIX OUT RADIATION FOG. BUT NE FLOW OFF LK SUP MIGHT TEND TO KEEP THE FOG/LO CLD MORE RESILIENT NEAR THE SHORE. DEEP MIXING TO H75 ON GFS FCST SDNGS (NAM/GFS BOTH SHOW H85 TEMPS ARND 10C) WOULD SUPPORT HI TEMPS APRCHG 70 AWAY FM LK MODERATION AS OBSVD IN NRN LWR MI THIS AFTN. BUT TEMPS NEAR LK SUP/ THE GREEN BAY SHOULD BE QUITE A BIT COOLER. SINCE GFS/NAM GENERATE SOME LGT QPF OVER NRN WI BTWN 18Z-24Z...CHECKED FOR THE POTENTIAL FOR SOME INSTABILITY SHRA. BUT EVEN FOR HI TEMPS REACHING AOA 70... UNABLE TO GET ANY SUBSTANTIVE CAPE WITH LLVLS DRIED BY MIXING AND WRMG MID LVLS UNDER UPR RDG. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... THE 500MB RIDGE LOOKS TO REMAIN IN PLACE OVER THE CWA UNTIL SUNDAY NIGHT. AT THAT TIME...SOUTHWESTERLY FLOW WILL BEGIN AS THE TROUGH OVER THE PACIFIC NORTHWEST SLOWLY EDGES EASTWARD TOWARDS THE GREAT LAKES REGION. CAN UNDERSTAND WHY THE TREND HAS CONTINUED...SLOWING THE ONSET OF PRECIPITATION DOWN MONDAY NIGHT AND TUESDAY. IN FACT...IT LOOKS MORE LIKE TUESDAY AFTERNOON BEFORE ANY SIGNIFICANT PRECIPITATION HITS THE WESTERN CWA. HPC GUIDANCE BACKS THIS SCENARIO UP. HOWEVER...THE 12Z RUNS OF THE NAM AND GFS HAVE QUICKENED THINGS UP ROUGHLY 6 HOURS FROM THEIR PREVIOUS RUNS. COMPARED TO THE OTHER OPTIONS...THE GFS WAS QUICKER. CAN NOT IGNORE THIS TREND...AND HAVE MADE SMALL ADJUSTMENTS WHILE ATTEMPTING TO NOT JUMP AROUND TOO MUCH DURING THIS PERIOD. THE PACIFIC TROUGH LOOKS TO SHIFT NE INSTEAD OF STRAIGHT EAST...RESULTING IN A MORE NORTHERLY BROAD SCALE TROUGH FOR US TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON. STILL...CONTINUE TO LOOK FOR THE POTENTIAL FOR HEAVY RAIN AND THUNDERSTORMS AHEAD AND ALONG THE COLD FRONT AS IT SLIDES ACROSS. A HIGH PRESSURE RIDGE IS THEN FIGURED WEDNESDAY NIGHT THROUGH THE DAYTIME HOURS THURSDAY. THEN AGAIN...ANOTHER PACIFIC TROUGH SHOULD EDGE OVER THE WESTERN STATES TO NE MN/SOUTHERN ONTARIO BY 12Z SATURDAY. THE GFS IS THEN MUCH MORE PROGRESSIVE...TRYING TO DIVE THE TROUGH OVER THE SOUTHERN LAKES WHILE OTHER MODELS SEEM TO CONTINUE WITH A GENERAL E TO NE TRACK. FROM FRIDAY ON THE FORECAST BECOMES A BUGABOO. WITH MODEL VARIABILITY PRETTY HIGH...AND FORECAST CONFIDENCE RUNNING LOW AT THIS TIME FRAME...WILL OPT TO UTILIZED HPC GUIDANCE HEAVILY. THIS GENERALLY MEANT FOLLOWING A 00Z ECMWF FORECAST...WITH A BLEND OF ITS ENSEMBLE MEAN. && .HYDROLOGY (ISSUED AT 1050 AM EDT SATURDAY)... LOCATIONS THAT RECEIVED THE LEAST RAINFALL OVER THE LAST 24 HOURS...IN SOUTHERN AND EASTERN UPPER MICHIGAN...WERE ALSO THE LOCATIONS WITH THE SMALLEST SNOWMELT CONCERNS. LOCATIONS TO THE NORTH AND WEST RECEIVED BETWEEN A QUARTER TO A HALF INCH OF RAINFALL...ADDING TO SNOWMELT GOING INTO ALREADY HIGH RIVERS. HIGHS IN THE 40S SATURDAY...AND NEAR 60 ON SUNDAY AND MONDAY WILL RESULT IN RIVER LEVELS CONTINUING TO RISE. LATEST FORECASTS FROM THE RIVER FORECAST CENTER SHOW HIGHER CREST VALUES THAN PREVIOUSLY ISSUED FORECASTS. LOCATIONS WITH THE HIGHEST CONCERN INCLUDE THE CHOCOLAY RIVER NEAR HARVEY...AND THE STURGEON RIVER NEAR CHASSELL. AFTER DISCUSSION WITH THE CMX COUNTY EMERGENCY MANAGER AROUND NOON...OPTED TO ISSUE FLOOD WARNING FOR THE STURGEON RIVER AT CHASSELL WITH IMPENDING SLOW RISE TOWARD FLOOD STAGE. FOR CONTINUED UPDATES ON THE RIVERS... PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 00Z TAF ISSUANCE)... IT`S A VERY DIFFICULT FCST THIS EVENING. DRY AIR IS MAKING SOME INROADS FROM THE E ACROSS PORTIONS OF CNTRL UPPER MI PER SFC OBS WHICH HAVE SHOWN LOW CIGS BREAKING...BUT HIGH CLOUDS HAVE MADE IT IMPOSSIBLE TO SEE ON VIS SATELLITE IMAGERY EXACTLY WHERE AND HOW FAST THE LOW CLOUDS ARE CLEARING. IN ANYCASE...IT APPEARED LOW CLOUDS WOULD SCATTER OUT AT KCMX/KSAW THIS EVENING AS SOME DRYING OCCURS FROM THE E. HOWEVER...HAVE NOW OPTED FOR A MUCH MORE PESSIMISTIC FCST TONIGHT. SINCE SFC DWPTS ACROSS UPPER MI/LAKE SUPERIOR AND SURROUNDING REGION HAVE VERY SIMILAR VALUES TO CURRENT TEMPS AT KSAW/KCMX AND LOW-LEVEL WIND FLOW WILL RETAIN AN UPSLOPE COMPONENT THRU THE NIGHT AT BOTH SITES...IT SEEMS UNLIKELY THAT STRATUS (LIFR/IFR CIGS) WILL BREAK. ALSO...EXPECT VIS TO DROP SLOWLY TO IFR AS FOG DEVELOPS. POTENTIAL EXISTS FOR LIFR VIS IN FOG LATER IN THE NIGHT. SHOULD SEE CONDITIONS AT BOTH SITES IMPROVE TO VFR EARLY SUN AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE FROM JAMES BAY INTO QUEBEC TO REMAIN NEARLY STATIONARY THROUGH SUNDAY. MEANWHILE...LOW PRESSURE OVER SOUTHERN LAKE MICHIGAN IS EXPECTED TO DISSIPATE OVER THE SOUTHERN GREAT LAKES BY LATE SUNDAY. ALSO ON SUNDAY...LOW PRESSURE WILL DEVELOP OVER THE NORTHERN ROCKIES...THEN LIFT NORTHEAST TO HUDSON BAY BY TUESDAY EVENING AND DRAG A TROUGH OF LOW PRESSURE ACROSS THE WESTERN GREAT LAKES BY TUESDAY NIGHT. BEHIND THIS TROUGH...HIGH PRESSURE WILL SLIDE SOUTHEAST ACROSS THE GREAT LAKES REGION ON WEDNESDAY. A LOW PRESSURE SYSTEM DEVELOPING OVER THE CENTRAL PLAINS WILL THEN APPROACH THE WESTERN GREAT LAKES REGION ON THURSDAY. FOR THE MOST PART...WINDS SHOULD REMAIN UNDER 20 KTS INTO TUESDAY. EXPECT STRONGER SOUTH WINDS OVER THE EAST IN THE ADVANCE OF THE APPROACHING TROUGH ON TUESDAY/TUESDAY NIGHT. STRONGER WEST TO NORTHWEST WINDS WILL ARRIVE FOLLOWING THE PASSAGE OF THE TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...KC LONG TERM...KF HYDROLOGY...TG/KC AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 710 PM EDT SAT APR 19 2008 .AVIATION...LOW PRESSURE WILL STEADILY MOVE EAST ACROSS THE OHIO VALLEY. FAIR AMOUNT OF MID/HIGH CLOUDS AND HAZE ALOFT...BUT SHOWERS WILL STAY SOUTH OF ALL TAF SITES. WEATHER WILL REMAIN WARM...WITH LAKE BREEZES DEVELOPING AGAIN SUNDAY AFTERNOON AGAINST A BACKDROP OF OTHERWISE LIGHT EASTERLY WINDS. VFR THRU THE FORECAST. JZ && .DISCUSSION...ISSUED 303 PM SAT APR 19... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LEVEL LOW SPINNING OVER THE SOUTHERN IL-IN BORDER AND A BROAD AREA OF SURFACE LOW PRESSURE OVER THE SOUTHERN GREAT LAKES. BANDS OF MID AND UPPER LEVEL CLOUD COVER CONTINUE TO ROTATE ACROSS NORTHERN MICHIGAN WITH HOLES IN THE CIRRUS SHIELD APPEARING EVERY NOW AND THEN. THESE CLOUDS HAVE NOT PREVENTED TEMPERATURES FROM RAPIDLY WARMING INTO THE LOW TO MID 70S INLAND. WITH PRECIP WELL TO THE SOUTH OVER FAR SOUTHERN LOWER MICHIGAN...MAIN FORECAST CONCERNS INCLUDE TEMPS AND SKY COVER TONIGHT...THEN SMALL CHANCES OF PRECIP ALONG LAKE BREEZE BOUNDARIES TOMORROW. TONIGHT...UPPER LOW WILL DRIFT SLIGHTLY SOUTH OF EAST AS IT CUTS ACROSS THE OHIO RIVER VALLEY TO THE CENTRAL APPALACHIANS. SPOKE OF UPPER LEVEL MOISTURE WILL PINWHEEL ACROSS NORTHERN MICHIGAN TONIGHT...BUT FORCING AND DEEP MOISTURE WILL REMAIN WELL SOUTH OF THE REGION. THAT LEAVES TEMPERATURES AND SKY COVER TO THINK ABOUT. LOWS LAST NIGHT DIPPED INTO THE MIDDLE AND UPPER 30S ACROSS NE LOWER WHERE CLEAR SKIES HUNG ON THE LONGEST. DO NOT THINK THAT WILL HAPPEN TONIGHT DUE TO THE CIRRUS SHIELD...EVEN THOUGH THIS CIRRUS WILL THIN OVERNIGHT ACROSS NORTHERN LOWER. SO HAVE KEPT LOWS SIMILAR TO LAST NIGHT EXCEPT RAISED THEM A FEW DEGREES OVER NE LOWER. LOWS IN THE 40S. TOMORROW...UPPER LOW WILL MEANDER ACROSS THE CENTRAL APPALACHIANS WHILE MID-LEVEL HEIGHTS SLOWLY BUILD ACROSS THE NORTHERN GREAT LAKES. NO LARGE-SCALE FORCING TO SPEAK UP WITH THE BUILDING RIDGE...BUT STILL HINTS THAT LOCALIZED CONVERGENCE WILL SETUP ACROSS THE SW CWA WITH PREVAILING EAST FLOW BUTTING HEADS AGAINST LAKE BREEZES OFF OF LAKE MICHIGAN AND GRAND TRAVERSE BAY. BOTH NAM/GFS SPIT OUT QPF CENTERED AROUND WEXFORD COUNTY...BUT THINK THIS IS MORE OF A BY-PRODUCT OF OVER-GENEROUS SURFACE DEWPOINTS...WHICH BOTH MODELS SHOW IN THE LOWER TO MID 50S. DEEP MIXING UP TO 775MB SUGGESTS DEWPOINTS WILL MIX OUT TO AROUND 48F. USING A TEMP OF 72F...THIS WOULD YIELD SKINNY ML CAPES AROUND 200 J/KG IN THE MORE MOIST NAM SOLUTION...WHILE THE DRIER GFS SUGGESTS TOO MUCH CIN WILL EXIST TO TRIGGER A SHOWER. GIVEN THE INCREASING SUBSIDENCE THROUGH THE DAY...LEAN MORE TOWARD THE DRIER SOLUTION AND WILL LEAVE POPS OUT OF THE FORECAST. ANOTHER WARM DAY ON TAP WITH HIGHS RANGING FROM THE MID 60S NORTH/NEAR LAKESHORES...TO THE LOWER 70S INLAND. MPC SUN NIGHT THRU MON NIGHT...RATHER QUIET PERIOD OF WX EXPECTED TO CONTINUE...THOUGH A FEW FCST CONCERNS REMAIN...NAMELY TEMPS MON AFTN ALONG WITH ANY SMALL PRECIP CHANCES THRU THE PERIOD. POTENT CLOSED LOW SPINNING OVR SOUTHERN IN THIS AFTN PROGGED TO SLIP INTO VIRGINIA BY EARLY MON...WITH BROAD SHORTWAVE RIDGING BUILDING ACRS THE LAKES IN ADVANCE OF NEXT UPSTREAM TROUGH OVR THE NORTHWEST. HOWEVER... CONCERN REGARDING POTENTIAL PRECIP STEMS FROM BROAD PLUME OF WRAP AROUND MOISTURE PROGGED TO ADVECT BACK INTO THE REGION SUN NIGHT TIMEFRAME...AS UPR GYRE ABLE TO TAP ADDITIONAL MOISTURE FROM THE ATLANTIC. INTERESTING TO NOTE BOTH NAM AND GFS SPIT OUT A HINT OF MEASURABLE PRECIP SUN NIGHT/EARLY MON THOUGH DIFFICULT TO FORESEE THIS GIVEN OVERALL LACK OF MID/UPR LEVEL MOISTURE AND FORCING...WITH ONLY SOME WEAK HINT OF CHANNELED VORT (REMNANTS OF CLOSED LOW TO THE SOUTH TODAY) HEADING NORTH THRU THE NIGHT. THUS WILL MAINTAIN DRY FCST AT THIS TIME. HEADING INTO MON AFTN...APPEARS ANOTHER WARM DAY ON TAP WITH DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING UPR TROUGH...THOUGH OVERALL LACK OF MIXING PER LOW LEVEL RIDGE AXIS DRAPED OVERHEAD SHOULD KNOCK A FEW DEGREE OFF POTENTIAL HIGHS (READINGS MAINLY MID/UPR 60S LOOK GOOD). DESPITE GOOD HEATING AND LIKELY LAKE BREEZE CONVERGENCE ALONG THE LAKE MICHIGAN SIDE... DIFFICULT TO SEE CONVECTION (OTHER THAN A FAIRLY HEALTHY CU FIELD) FIRING DESPITE AN INCREASE IN BOUNDARY LAYER MOISTURE...AS MID LEVEL SUBSIDENCE INVERSION BUILDS THRU THE DAY. LATER PERIODS (TUE THRU SAT)...PATTERN TO REMAIN QUITE BLOCKY THRU THE EXTENDED PORTION OF THE FCST...OWING TO HIGHLY AMPLIFIED/ CLOSED MID LEVEL RIDGE ACRS CENTRAL/EASTERN ALASKA...IMPLYING SIGNIFICANT DOWNSTREAM TROUGHING INTO THE WESTERN CONUS. INDEED... THIS TYPE OF PATTERN IS WHAT THE MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST...WITH INITIAL CLOSED LOW (EVIDENT THIS AFTN NEAR THE BRITISH COLUMBIA/WASHINGTON STATE BORDER) AND ASSOCIATED ENERGY SHEARING OUT INTO THE NORTHERN PLAINS/UPR MIDWEST ON TUE...OWING TO BRIEF DISRUPTION OF BLOCKING FLOW ACRS THE EASTERN PACIFIC AS ENERGY UNDERCUTS THE RIDGE. END RESULT FOR NORTHERN MI WILL BE INCREASING CHANCES FOR PRECIP TUE NIGHT AS ASSOCIATED SFC FRONT AND WEAKENING FORCING SLIDES THRU THE REGION. WILL CONTINUE THUNDER MENTION AS WELL WITH EXPECTED DECENT MOISTURE TAP INTO THE AREA VIA OPEN GULF...AND MODEL PROGS OF SHOWALTER INDICES DIPPING WELL BELOW 0C ALONG WITH STEEPER MID LEVEL LAPSE RATE PLUME OVERHEAD. PONDERED BRINGING SMALL POPS BACK INTO THE PICTURE FOR TUE AFTN AS MOISTURE INCREASES AHEAD OF THE FRONT...WITH POTENTIAL FOR BRIEF CONVECTION TO POP AHEAD OF THE BOUNDARY GIVEN EXPECTED HEATING AND LIKELY LOW LEVEL WEAK UPSLOPE REGIME INTO THE HIGHER TERRAIN PER BACKING OF FLOW AHEAD OF THE FRONT...THOUGH ANYTHING ISOLATED AT BEST SO DRY FCST WILL CONTINUE. TEMPS TUE IFFY PENDING DEGREE OF SUN...THOUGH POTENTIAL IS THERE FOR A VERY WARM DAY WITH REGION IN THE THERMAL RIDGE AHEAD OF THE FRONT. WILL RUN WITH MID 60S TO LOWER 70S AREAWIDE. STILL LOOKS LIKE A DRY AND MORE SEASONABLE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGING AND ASSOCIATED SUBSIDENCE/DRYING TAKE HOLD. 00Z GUIDANCE NUMBERS APPEAR A BIT TOO COOL GIVEN EXPECTED SUN...SO WILL RUN WITH TEMPS UPR 50S TO MID 60S. THEREAFTER...GUIDANCE BEGINS TO DIVERGE ON AMPLITUDE OF ADDITIONAL WESTERN TROUGHING THU/FRI...THOUGH PATTERN RECOGNITION WITH DEEP LAYER/MERIDIONAL RIDGE BECOMING RE-ESTABLISHED ACRS ALASKA CERTAINLY ARGUES FOR THE ECMWF/GEFS MEAN SOLUTIONS OF A DEEPER WESTERN TROUGH. REGARDLESS OF EVENTUAL SOLUTION...IMPLICATION FOR THE CWA IS ADDITIONAL PRECIP CHANCES FRI/SAT TIMEFRAME AS LEE CYCLOGENESIS GETS GOING ON THE PLAINS...WITH ASSOCIATED COLD FRONT HEADING EAST BY THE WEEKEND. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 350 PM EDT SAT APR 19 2008 .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF ALG THE W COAST AND BLDG RDG OVER THE E HALF OF NAMERICA. CUTOFF LO UNDER THE BLDG RDG IS MOVING E THRU THE OH VALLEY WHILE ANOTHER SHRTWV IS LIFTING INTO WRN LK SUP. INTERACTION OF THIS SHRTWV/ ASSOCIATED UPR DVGC/DPVA/H85-5 QVECTOR CNVGC WITH DEEPER MSTR SHOWN ON THE 12Z MPX RAOB IS CAUSING SCT -SHRA/QUITE A BIT OF LO CLD OVER THE NW HALF OF THE FA EARLY THIS AFTN. BUT 12Z GRB/APX RAOBS SHOW MUCH DRIER AIR IS PRESENT TO THE SE ABV LINGERING SHALLOW MSTR. WITH SE H85 WINDS BTWN CUTOFF LO IN THE OH VALLEY AND HUDSON BAY HI PRES...THIS DRY IS OVERSPRDG THE FA...HAS ENDED THE PCPN OVER THE SCNTRL AND E...AND IS TENDING TO DIMINISH THE SHRA COVG OVER THE NW. .SHORT TERM (TONIGHT AND SUNDAY)... FOR TNGT...GENERAL MSLP/UPR HGT RISES FCST OVER THE UPR LKS DOWNSTREAM OF DEEPENING TROF IN THE W. WITH PERSISTENT ELY FLOW BTWN HUDSON BAY HI AND DEPARTING CLOSED LO IN THE OH VALLEY...EXPECT DRIER AIR IN THAT DIRECTION TO CONTINUE MAKING INROADS ESE-WNW THRU THE FA. WL RESTRICT MENTION OF POPS THIS EVNG TO THE W BEFORE DROPPING MENTION OF PCPN EXCEPT OVER WRN LK SUP UNDER LINGERING DEEPER MSTR CLOSER TO INCRSGLY SHEARED SHRTWV IMPACTING THAT AREA. EVEN THOUGH THE MID LVLS WL BE DRYING OUT...SUSPECT THE LLVL MSTR WL BE HARDER TO DISLODGE. THIS LLVL MSTR WL BE MOST RESILIENT OVER THE NW IN AREAS WHERE LO CLDS HAVE LINGERED THRU THE DAY AND LIMITED INSOLATION/MIXING. SO WL FCST AREAS OF FOG TO DVLP DESPITE SOME LINGERING HI CLD. HOWEVER...CONDITIONS DON`T APPEAR IDEAL FOR DENSE FOG FORMATION WITH FCST RELATIVELY SHARP PRES GRADIENT BTWN HI TO THE N AND LO IN THE OH VALLEY. EXPECT ONLY PTCHY FOG OVER THE E CONSIDERING THE DEEPER MIXING EVIDENT THERE THIS AFTN. WL TEND TO UNDERCUT MOS FCST LO TEMPS OVER THE INTERIOR E CLOSER TO THE CORE OF THE DRIEST AIR. ON SUN...ACYC ENE FLOW WL DOMINATE THE UPR GRT LKS. WITH DRY AIR ABV THE SFC IN THE MRNG...INSOLATION SHOULD MIX OUT RADIATION FOG. BUT NE FLOW OFF LK SUP MIGHT TEND TO KEEP THE FOG/LO CLD MORE RESILIENT NEAR THE SHORE. DEEP MIXING TO H75 ON GFS FCST SDNGS (NAM/GFS BOTH SHOW H85 TEMPS ARND 10C) WOULD SUPPORT HI TEMPS APRCHG 70 AWAY FM LK MODERATION AS OBSVD IN NRN LWR MI THIS AFTN. BUT TEMPS NEAR LK SUP/ THE GREEN BAY SHOULD BE QUITE A BIT COOLER. SINCE GFS/NAM GENERATE SOME LGT QPF OVER NRN WI BTWN 18Z-24Z...CHECKED FOR THE POTENTIAL FOR SOME INSTABILITY SHRA. BUT EVEN FOR HI TEMPS REACHING AOA 70... UNABLE TO GET ANY SUBSTANTIVE CAPE WITH LLVLS DRIED BY MIXING AND WRMG MID LVLS UNDER UPR RDG. && .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... THE 500MB RIDGE LOOKS TO REMAIN IN PLACE OVER THE CWA UNTIL SUNDAY NIGHT. AT THAT TIME...SOUTHWESTERLY FLOW WILL BEGIN AS THE TROUGH OVER THE PACIFIC NORTHWEST SLOWLY EDGES EASTWARD TOWARDS THE GREAT LAKES REGION. CAN UNDERSTAND WHY THE TREND HAS CONTINUED...SLOWING THE ONSET OF PRECIPITATION DOWN MONDAY NIGHT AND TUESDAY. IN FACT...IT LOOKS MORE LIKE TUESDAY AFTERNOON BEFORE ANY SIGNIFICANT PRECIPITATION HITS THE WESTERN CWA. HPC GUIDANCE BACKS THIS SCENARIO UP. HOWEVER...THE 12Z RUNS OF THE NAM AND GFS HAVE QUICKENED THINGS UP ROUGHLY 6 HOURS FROM THEIR PREVIOUS RUNS. COMPARED TO THE OTHER OPTIONS...THE GFS WAS QUICKER. CAN NOT IGNORE THIS TREND...AND HAVE MADE SMALL ADJUSTMENTS WHILE ATTEMPTING TO NOT JUMP AROUND TOO MUCH DURING THIS PERIOD. THE PACIFIC TROUGH LOOKS TO SHIFT NE INSTEAD OF STRAIGHT EAST...RESULTING IN A MORE NORTHERLY BROAD SCALE TROUGH FOR US TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON. STILL...CONTINUE TO LOOK FOR THE POTENTIAL FOR HEAVY RAIN AND THUNDERSTORMS AHEAD AND ALONG THE COLD FRONT AS IT SLIDES ACROSS. A HIGH PRESSURE RIDGE IS THEN FIGURED WEDNESDAY NIGHT THROUGH THE DAYTIME HOURS THURSDAY. THEN AGAIN...ANOTHER PACIFIC TROUGH SHOULD EDGE OVER THE WESTERN STATES TO NE MN/SOUTHERN ONTARIO BY 12Z SATURDAY. THE GFS IS THEN MUCH MORE PROGRESSIVE...TRYING TO DIVE THE TROUGH OVER THE SOUTHERN LAKES WHILE OTHER MODELS SEEM TO CONTINUE WITH A GENERAL E TO NE TRACK. FROM FRIDAY ON THE FORECAST BECOMES A BUGABOO. WITH MODEL VARIABILITY PRETTY HIGH...AND FORECAST CONFIDENCE RUNNING LOW AT THIS TIME FRAME...WILL OPT TO UTILIZED HPC GUIDANCE HEAVILY. THIS GENERALLY MEANT FOLLOWING A 00Z ECMWF FORECAST...WITH A BLEND OF ITS ENSEMBLE MEAN. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... EXPECT SLOW IMPROVEMENT IN CIG/VSBY TDAY WITH DIURNAL HTG AND ADVECTION OF DRY AIR JUST ABV SHALLOW MOIST LYR AS SHOWN ON THE 12Z APX RAOB/RECENT TAMDAR SDNG FM CIU. CONDITIONS WL BE SLOWEST TO IMPROVE AT CMX FARTHER FM THIS DRY AIR THAT IS ARRIVING FM THE ESE... AND LO CLDS ARE NOT LIKELY TO BREAK UP THERE UNTIL THIS EVNG. WITH CONTINUED DRYING ALF AND SNOW MELT TNGT...EXPECT MORE RADIATION FOG TO DVLP OVERNGT WITH LIFR VSBYS LIKELY. BEST CHC FOR LO IFR CIG WL BE AT SAW WITH FVRBL UPSLOPE NNE WIND COMPONENT. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE FROM JAMES BAY INTO QUEBEC TO REMAIN NEARLY STATIONARY THROUGH SUNDAY. MEANWHILE...LOW PRESSURE OVER SOUTHERN LAKE MICHIGAN IS EXPECTED TO DISSIPATE OVER THE SOUTHERN GREAT LAKES BY LATE SUNDAY. ALSO ON SUNDAY...LOW PRESSURE WILL DEVELOP OVER THE NORTHERN ROCKIES...THEN LIFT NORTHEAST TO HUDSON BAY BY TUESDAY EVENING AND DRAG A TROUGH OF LOW PRESSURE ACROSS THE WESTERN GREAT LAKES BY TUESDAY NIGHT. BEHIND THIS TROUGH...HIGH PRESSURE WILL SLIDE SOUTHEAST ACROSS THE GREAT LAKES REGION ON WEDNESDAY. A LOW PRESSURE SYSTEM DEVELOPING OVER THE CENTRAL PLAINS WILL THEN APPROACH THE WESTERN GREAT LAKES REGION ON THURSDAY. FOR THE MOST PART...WINDS SHOULD REMAIN UNDER 20 KTS INTO TUESDAY. EXPECT STRONGER SOUTH WINDS OVER THE EAST IN THE ADVANCE OF THE APPROACHING TROUGH ON TUESDAY/TUESDAY NIGHT. STRONGER WEST TO NORTHWEST WINDS WILL ARRIVE FOLLOWING THE PASSAGE OF THE TROUGH. && .HYDROLOGY (ISSUED AT 1050 AM EDT SATURDAY)... LOCATIONS THAT RECEIVED THE LEAST RAINFALL OVER THE LAST 24 HOURS...IN SOUTHERN AND EASTERN UPPER MICHIGAN...WERE ALSO THE LOCATIONS WITH THE SMALLEST SNOWMELT CONCERNS. LOCATIONS TO THE NORTH AND WEST RECEIVED BETWEEN A QUARTER TO A HALF INCH OF RAINFALL...ADDING TO SNOWMELT GOING INTO ALREADY HIGH RIVERS. HIGHS IN THE 40S SATURDAY...AND NEAR 60 ON SUNDAY AND MONDAY WILL RESULT IN RIVER LEVELS CONTINUING TO RISE. LATEST FORECASTS FROM THE RIVER FORECAST CENTER SHOW HIGHER CREST VALUES THAN PREVIOUSLY ISSUED FORECASTS. LOCATIONS WITH THE HIGHEST CONCERN INCLUDE THE CHOCOLAY RIVER NEAR HARVEY...AND THE STURGEON RIVER NEAR CHASSELL. AFTER DISCUSSION WITH THE CMX COUNTY EMERGENCY MANAGER AROUND NOON...OPTED TO ISSUE FLOOD WARNING FOR THE STURGEON RIVER AT CHASSELL WITH IMPENDING SLOW RISE TOWARD FLOOD STAGE. FOR CONTINUED UPDATES ON THE RIVERS... PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...KC MARINE...KC HYDROLOGY...TG/KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 303 PM EDT SAT APR 19 2008 .DISCUSSION...LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LEVEL LOW SPINNING OVER THE SOUTHERN IL-IN BORDER AND A BROAD AREA OF SURFACE LOW PRESSURE OVER THE SOUTHERN GREAT LAKES. BANDS OF MID AND UPPER LEVEL CLOUD COVER CONTINUE TO ROTATE ACROSS NORTHERN MICHIGAN WITH HOLES IN THE CIRRUS SHIELD APPEARING EVERY NOW AND THEN. THESE CLOUDS HAVE NOT PREVENTED TEMPERATURES FROM RAPIDLY WARMING INTO THE LOW TO MID 70S INLAND. WITH PRECIP WELL TO THE SOUTH OVER FAR SOUTHERN LOWER MICHIGAN...MAIN FORECAST CONCERNS INCLUDE TEMPS AND SKY COVER TONIGHT...THEN SMALL CHANCES OF PRECIP ALONG LAKE BREEZE BOUNDARIES TOMORROW. TONIGHT...UPPER LOW WILL DRIFT SLIGHTLY SOUTH OF EAST AS IT CUTS ACROSS THE OHIO RIVER VALLEY TO THE CENTRAL APPALACHIANS. SPOKE OF UPPER LEVEL MOISTURE WILL PINWHEEL ACROSS NORTHERN MICHIGAN TONIGHT...BUT FORCING AND DEEP MOISTURE WILL REMAIN WELL SOUTH OF THE REGION. THAT LEAVES TEMPERATURES AND SKY COVER TO THINK ABOUT. LOWS LAST NIGHT DIPPED INTO THE MIDDLE AND UPPER 30S ACROSS NE LOWER WHERE CLEAR SKIES HUNG ON THE LONGEST. DO NOT THINK THAT WILL HAPPEN TONIGHT DUE TO THE CIRRUS SHIELD...EVEN THOUGH THIS CIRRUS WILL THIN OVERNIGHT ACROSS NORTHERN LOWER. SO HAVE KEPT LOWS SIMILAR TO LAST NIGHT EXCEPT RAISED THEM A FEW DEGREES OVER NE LOWER. LOWS IN THE 40S. TOMORROW...UPPER LOW WILL MEANDER ACROSS THE CENTRAL APPALACHIANS WHILE MID-LEVEL HEIGHTS SLOWLY BUILD ACROSS THE NORTHERN GREAT LAKES. NO LARGE-SCALE FORCING TO SPEAK UP WITH THE BUILDING RIDGE...BUT STILL HINTS THAT LOCALIZED CONVERGENCE WILL SETUP ACROSS THE SW CWA WITH PREVAILING EAST FLOW BUTTING HEADS AGAINST LAKE BREEZES OFF OF LAKE MICHIGAN AND GRAND TRAVERSE BAY. BOTH NAM/GFS SPIT OUT QPF CENTERED AROUND WEXFORD COUNTY...BUT THINK THIS IS MORE OF A BY-PRODUCT OF OVER-GENEROUS SURFACE DEWPOINTS...WHICH BOTH MODELS SHOW IN THE LOWER TO MID 50S. DEEP MIXING UP TO 775MB SUGGESTS DEWPOINTS WILL MIX OUT TO AROUND 48F. USING A TEMP OF 72F...THIS WOULD YIELD SKINNY ML CAPES AROUND 200 J/KG IN THE MORE MOIST NAM SOLUTION...WHILE THE DRIER GFS SUGGESTS TOO MUCH CIN WILL EXIST TO TRIGGER A SHOWER. GIVEN THE INCREASING SUBSIDENCE THROUGH THE DAY...LEAN MORE TOWARD THE DRIER SOLUTION AND WILL LEAVE POPS OUT OF THE FORECAST. ANOTHER WARM DAY ON TAP WITH HIGHS RANGING FROM THE MID 60S NORTH/NEAR LAKESHORES...TO THE LOWER 70S INLAND. MPC SUN NIGHT THRU MON NIGHT...RATHER QUIET PERIOD OF WX EXPECTED TO CONTINUE...THOUGH A FEW FCST CONCERNS REMAIN...NAMELY TEMPS MON AFTN ALONG WITH ANY SMALL PRECIP CHANCES THRU THE PERIOD. POTENT CLOSED LOW SPINNING OVR SOUTHERN IN THIS AFTN PROGGED TO SLIP INTO VIRGINIA BY EARLY MON...WITH BROAD SHORTWAVE RIDGING BUILDING ACRS THE LAKES IN ADVANCE OF NEXT UPSTREAM TROUGH OVR THE NORTHWEST. HOWEVER... CONCERN REGARDING POTENTIAL PRECIP STEMS FROM BROAD PLUME OF WRAP AROUND MOISTURE PROGGED TO ADVECT BACK INTO THE REGION SUN NIGHT TIMEFRAME...AS UPR GYRE ABLE TO TAP ADDITIONAL MOISTURE FROM THE ATLANTIC. INTERESTING TO NOTE BOTH NAM AND GFS SPIT OUT A HINT OF MEASURABLE PRECIP SUN NIGHT/EARLY MON THOUGH DIFFICULT TO FORESEE THIS GIVEN OVERALL LACK OF MID/UPR LEVEL MOISTURE AND FORCING...WITH ONLY SOME WEAK HINT OF CHANNELED VORT (REMNANTS OF CLOSED LOW TO THE SOUTH TODAY) HEADING NORTH THRU THE NIGHT. THUS WILL MAINTAIN DRY FCST AT THIS TIME. HEADING INTO MON AFTN...APPEARS ANOTHER WARM DAY ON TAP WITH DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING UPR TROUGH...THOUGH OVERALL LACK OF MIXING PER LOW LEVEL RIDGE AXIS DRAPED OVERHEAD SHOULD KNOCK A FEW DEGREE OFF POTENTIAL HIGHS (READINGS MAINLY MID/UPR 60S LOOK GOOD). DESPITE GOOD HEATING AND LIKELY LAKE BREEZE CONVERGENCE ALONG THE LAKE MICHIGAN SIDE... DIFFICULT TO SEE CONVECTION (OTHER THAN A FAIRLY HEALTHY CU FIELD) FIRING DESPITE AN INCREASE IN BOUNDARY LAYER MOISTURE...AS MID LEVEL SUBSIDENCE INVERSION BUILDS THRU THE DAY. LATER PERIODS (TUE THRU SAT)...PATTERN TO REMAIN QUITE BLOCKY THRU THE EXTENDED PORTION OF THE FCST...OWING TO HIGHLY AMPLIFIED/ CLOSED MID LEVEL RIDGE ACRS CENTRAL/EASTERN ALASKA...IMPLYING SIGNIFICANT DOWNSTREAM TROUGHING INTO THE WESTERN CONUS. INDEED... THIS TYPE OF PATTERN IS WHAT THE MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST...WITH INITIAL CLOSED LOW (EVIDENT THIS AFTN NEAR THE BRITISH COLUMBIA/WASHINGTON STATE BORDER) AND ASSOCIATED ENERGY SHEARING OUT INTO THE NORTHERN PLAINS/UPR MIDWEST ON TUE...OWING TO BRIEF DISRUPTION OF BLOCKING FLOW ACRS THE EASTERN PACIFIC AS ENERGY UNDERCUTS THE RIDGE. END RESULT FOR NORTHERN MI WILL BE INCREASING CHANCES FOR PRECIP TUE NIGHT AS ASSOCIATED SFC FRONT AND WEAKENING FORCING SLIDES THRU THE REGION. WILL CONTINUE THUNDER MENTION AS WELL WITH EXPECTED DECENT MOISTURE TAP INTO THE AREA VIA OPEN GULF...AND MODEL PROGS OF SHOWALTER INDICES DIPPING WELL BELOW 0C ALONG WITH STEEPER MID LEVEL LAPSE RATE PLUME OVERHEAD. PONDERED BRINGING SMALL POPS BACK INTO THE PICTURE FOR TUE AFTN AS MOISTURE INCREASES AHEAD OF THE FRONT...WITH POTENTIAL FOR BRIEF CONVECTION TO POP AHEAD OF THE BOUNDARY GIVEN EXPECTED HEATING AND LIKELY LOW LEVEL WEAK UPSLOPE REGIME INTO THE HIGHER TERRAIN PER BACKING OF FLOW AHEAD OF THE FRONT...THOUGH ANYTHING ISOLATED AT BEST SO DRY FCST WILL CONTINUE. TEMPS TUE IFFY PENDING DEGREE OF SUN...THOUGH POTENTIAL IS THERE FOR A VERY WARM DAY WITH REGION IN THE THERMAL RIDGE AHEAD OF THE FRONT. WILL RUN WITH MID 60S TO LOWER 70S AREAWIDE. STILL LOOKS LIKE A DRY AND MORE SEASONABLE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGING AND ASSOCIATED SUBSIDENCE/DRYING TAKE HOLD. 00Z GUIDANCE NUMBERS APPEAR A BIT TOO COOL GIVEN EXPECTED SUN...SO WILL RUN WITH TEMPS UPR 50S TO MID 60S. THEREAFTER...GUIDANCE BEGINS TO DIVERGE ON AMPLITUDE OF ADDITIONAL WESTERN TROUGHING THU/FRI...THOUGH PATTERN RECOGNITION WITH DEEP LAYER/MERIDIONAL RIDGE BECOMING RE-ESTABLISHED ACRS ALASKA CERTAINLY ARGUES FOR THE ECMWF/GEFS MEAN SOLUTIONS OF A DEEPER WESTERN TROUGH. REGARDLESS OF EVENTUAL SOLUTION...IMPLICATION FOR THE CWA IS ADDITIONAL PRECIP CHANCES FRI/SAT TIMEFRAME AS LEE CYCLOGENESIS GETS GOING ON THE PLAINS...WITH ASSOCIATED COLD FRONT HEADING EAST BY THE WEEKEND. LAWRENCE && .AVIATION... /ISSUED 100 PM EDT SAT APR 19 2008/ CIRRUS SHIELD WITH A FEW MID-LEVEL CLOUDS MIXED IN WILL PERSIST OVER THE AREA THROUGH THE TAF PERIOD AS LOW PRESSURE PASSES TO THE SOUTH. THIS CIRRUS WILL THIN TOMORROW MORNING. OVERALL...VFR CONDITIONS WILL REMAIN PRESENT. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 140 AM EDT SAT APR 19 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .UPDATE (ISSUED AT 1051 PM EDT)... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW MID/UPPER LEVEL LOW DRIFTING E THRU MISSOURI. LIKE LAST NIGHT...UPPER JET STREAK EXTENDS ROUGHLY FROM NE MN/LAKE SUPERIOR ENE ACROSS ONTARIO. UPPER DIVERGENCE IN THE RIGHT ENTRANCE OF JET AND CORRESPONDING BAND OF MIDLEVEL FRONTOGENESIS IS SUPPORTING PCPN ACROSS CNTRL/NRN WI INTO CNTRL UPPER MI IN DEEP MOISTURE BROUGHT N BY MIDLEVEL LOW. AS MIDLEVEL LOW CONTINUES EWD TONIGHT/SAT...LOW-LEVEL WINDS WILL BECOME MORE ERLY...ADVECTING DRIER AIR WWD INTO UPPER MI. AT THE SAME TIME...UPPER JET WILL BE WEAKENING. SO...LAST SURGE OF -RA WILL OCCUR DURING THE NIGHT...AND MAINLY OVER THE W HALF OF UPPER MI. GOING FCST HAS THIS COVERED WELL WITH HIGHEST POPS OVER WRN UPPER MI. LATER IN THE NIGHT...OPTED TO LWR POPS ACROSS PORTIONS OF CNTRL UPPER MI AS DRIER AIR IS ALREADY BEGINNING TO AFFECT HOW FAR E PCPN IS DEVELOPING ACROSS ERN WI. ALSO...EXPANDED AREA OF NO PCPN OVER THE FAR ERN FCST AREA. CARRIED THIS DRIER TREND INTO SAT BY REMOVING MENTION OF PCPN ROUGHLY E OF A KMQT TO KMNN LINE. FINAL NOTE...HIT FOG MENTION HARDER OVER NCNTRL UPPER MI UNDER MOIST UPSLOPING NE FLOW WHICH IS RESULTING IN MORE WIDESPREAD FOG WITH SOME PATCHY DENSE FOG. && .SYNOPSIS (ISSUED AT 515 PM EDT)... THE WEATHER OVER THE CNTRL CONUS WAS DOMINATED BY A MID/UPPER LEVEL LOW OVER NW MO. UPSTREAM ANOTHER H5 LOW WAS LOCATED OVER SRN BC WILL HAVE WEATHER IMPACTS INTO THE CNTRL CONUS NEXT WEEK AS IT SLIDES EAST. AT THE SFC...WEAK NE FLOW PREVAILED OVER THE REGION BTWN LOW PRES OVER SRN IA AND A RIDGE FROM NE CANADA INTO NW MN. RADARS INDICATED A LARGE AREA OF MAINLY LIGHT RAIN FROM NE IA THROUGH CNTRL WI...CNTRL UPPER MI AND ERN LAKE SUPERIOR. THE PCPN WAS SUPPORTED BY A 850-700 MB FGEN/DEFORMATION AND 300K ISENTROPIC ASCENT ALONG AND NORTH OF THE 850 MB FRONT. MOISTURE FUNNELING INTO THE PCPN ZONE WAS ABUNDANT WITH THE 12Z KGRB SOUNDING SHOWING PWAT TO NEAR AN INCH. && .SHORT TERM (TONIGHT AND SATURDAY ISSUED AT 515 PM EDT)... ALTHOUGH THE MID LEVEL LOW IS FCST TO SLIDE TO THE ESE INTO THE OHIO VALLEY THE DEFORMATION ZONE PCPN INTO CNTRL UPPER MI IS EXPECTED TO PERSIST WITH ONLY A SLOW SHIFT INTO THE MAINLY THE W HALF OF THE CWA. OVER THE E HALF...MAINLY DRY WEATHER IS EXPECTED. THE FCST GENERALLY FOLLOWED A BLEND OF THE 12Z NAM/GFS AND LCL HIGH RES WRF WITH THE PCPN PATTERN/POPS AND QPF. WITH 850 MB TEMPS TO AROUND 10C...AND POTENTIAL FOR BETTER INSOLATION...TEMPS ARE EXPECTED TO CLIMB INTO THE LOWER 60S. OTHERWISE...THICKER CLOUDS AND PCPN WEST SHOULD LIMIT MAX READINGS CLOSER TO 50. MDLS SUGGEST THAT THE FORCING WILL WEAKEN SAT...SO THAT THE MODEST PCPN SHOULD TAPER OFF. OVERALL QPF VALUES SHOULD REMAIN IN THE 0.25 TO .50 INCH RANGE TONIGHT AND REMAIN BLO A 0.25 INCH SATURDAY. .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... THE CWA WILL BE IN A COL...WITH GENERAL HIGH PRESSURE BOTH SATURDAY AND SUNDAY...AS TWO 500MB LOWS AFFECT OTHER PORTIONS OF THE NATION. THE FIRST WILL SLIDE FROM THE MID MISSISSIPPI VALLEY TO THE MID OHIO VALLEY. THE SECOND LOW...CURRENTLY OVER THE COAST MOUNTAINS OF WESTERN BRITISH COLUMBIA WILL CONTINUE TO ROTATE ALONG THE PACIFIC NORTHWEST. SW FLOW WILL BEGIN AND STRENGTHEN SUNDAY NIGHT AS THE PACIFIC NORTHWEST TROUGH SLIDES TO CENTRAL SASKATCHEWAN TUESDAY AFTERNOON...AND THEN TO HUDSON BAY BY WEDNESDAY AFTERNOON. CONTINUE TO GO SLOWER THAN A DAY AGO...WITH NO SIGNIFICANT PRECIPITATION FIGURED SUNDAY AND MONDAY. THIS SW FLOW ALOFT WILL BRING ABOUT COOLER THAN NORMAL TEMPERATURES ALONG WITH AN INCREASED CHANCE FOR WET WEATHER THROUGH MID WEEK. ALONG AND JUST AHEAD OF THE COLD FRONT...THE POTENTIAL EXISTS FOR MODERATE TO HEAVY RAINFALL PARTICULARLY WITH ANY THUNDERSTORMS THAT DEVELOP...MAINLY TUESDAY MORNING THROUGH TUESDAY AFTERNOON...AS THE SURFACE LOW OVER THE SOUTHERN PLAINS TUESDAY MORNING SLIDES NORTHEASTWARD TO WESTERN LAKE SUPERIOR BY LATE TUESDAY AFTERNOON. THE COLD FRONT IS EXPECTED TO SLIDE EAST OF THE CWA SHORTLY AFTER MIDNIGHT TUESDAY NIGHT. WE WILL NEED TO CONTINUE TO MONITOR HIGH RUNNING RIVERS THROUGH THIS PERIOD...AS ADDITIONAL RAINFALL COULD POSE A THREAT TO ALREADY SWOLLEN RIVERS AND STREAMS. HIGH PRESSURE WILL SLIDE IN AT THE SFC ON WEDNESDAYS...STILL WITH A BROAD-SCALE TROUGH AT 500MB. INCREASED AFTERNOON HIGH TEMPS ABOUT 5 DEGREES FOR WEDNESDAY...AS COLDER AIR KEEPS NORTH OF THE AREA WITH 850MB TEMPERATURES NOT DIPPING BELOW 0C UNTIL THURSDAY EVENING. FOR TUESDAY THROUGH FRIDAY...HPC GUIDANCE WAS A BLEND OF THE 00Z ECMWF ENSEMBLE MEAN AND 00Z NCEP GLOBAL ENSEMBLE MEAN...WITH LESS WEIGHTING TO THE OPERATIONAL 06Z-12Z GFS/00Z ECMWF/00Z UKMET. && .HYDROLOGY... PCPN COMBINED WITH CONTINUED MILD TEMPS FOR SNOWMELT...READINGS AROUND 40F TONIGHT AND AROUND 50F SAT...WILL LEAD TO STEADY CLIMB IN RIVER LEVELS ESPECIALLY OVER THE WEST HALF. FOR CONTINUED UPDATES ON THE RIVERS...PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 06Z TAF ISSUANCE)... CIGS AND/OR VIS AT KCMX AND KSAW HAVE CRASHED TO LIFR/VLIFR DURING THE EVENING. SEE LITTLE REASON FOR CONDITIONS TO IMPROVE DURING THE NIGHT WITH ABUNDANT LOW-LEVEL MOISTURE OVER THE AREA. CONDITIONS WILL BE WORST AT KSAW WITH PERSISTENT VLIFR VIS IN FOG UNDER UPSLOPING NE WINDS. IMPROVEMENT SHOULD BEGIN AT KSAW MID TO LATE MORNING WITH CONDITIONS TRENDING TO VFR IN THE AFTN AS DRIER AIR ARRIVES FROM THE E. AT KCMX...EXPECT OCCASIONAL -RA AND FOG TO KEEP VIS MOSTLY IN THE IFR RANGE THRU THE NIGHT. LIFR CIGS SHOULD BE THE RULE THRU MID MORNING WITH IMPROVEMENT TO MVFR BY MID AFTN AS -RA DIMINISHES/ENDS. VFR CONDITIONS EXPECTED AT KCMX IN THE EVENING. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE GRADUALLY SHIFTS NORTHEAST OF LAKE SUPERIOR THROUGH SUNDAY...WITH WINDS AT OR LESS THAN 20KT. STRONGER SE WINDS UP TO 30 KT COULD OCCUR ON TUESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SYNOPSIS/SHORT TERM...JLB LONG TERM...KF HYDROLOGY...JLB AVIATION...ROLFSON MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1051 PM EDT FRI APR 18 2008 .UPDATE... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW MID/UPPER LEVEL LOW DRIFTING E THRU MISSOURI. LIKE LAST NIGHT...UPPER JET STREAK EXTENDS ROUGHLY FROM NE MN/LAKE SUPERIOR ENE ACROSS ONTARIO. UPPER DIVERGENCE IN THE RIGHT ENTRANCE OF JET AND CORRESPONDING BAND OF MIDLEVEL FRONTOGENESIS IS SUPPORTING PCPN ACROSS CNTRL/NRN WI INTO CNTRL UPPER MI IN DEEP MOISTURE BROUGHT N BY MIDLEVEL LOW. AS MIDLEVEL LOW CONTINUES EWD TONIGHT/SAT...LOW-LEVEL WINDS WILL BECOME MORE ERLY...ADVECTING DRIER AIR WWD INTO UPPER MI. AT THE SAME TIME...UPPER JET WILL BE WEAKENING. SO...LAST SURGE OF -RA WILL OCCUR DURING THE NIGHT...AND MAINLY OVER THE W HALF OF UPPER MI. GOING FCST HAS THIS COVERED WELL WITH HIGHEST POPS OVER WRN UPPER MI. LATER IN THE NIGHT...OPTED TO LWR POPS ACROSS PORTIONS OF CNTRL UPPER MI AS DRIER AIR IS ALREADY BEGINNING TO AFFECT HOW FAR E PCPN IS DEVELOPING ACROSS ERN WI. ALSO...EXPANDED AREA OF NO PCPN OVER THE FAR ERN FCST AREA. CARRIED THIS DRIER TREND INTO SAT BY REMOVING MENTION OF PCPN ROUGHLY E OF A KMQT TO KMNN LINE. FINAL NOTE...HIT FOG MENTION HARDER OVER NCNTRL UPPER MI UNDER MOIST UPSLOPING NE FLOW WHICH IS RESULTING IN MORE WIDESPREAD FOG WITH SOME PATCHY DENSE FOG. && .SYNOPSIS (ISSUED AT 515 PM EDT)... THE WEATHER OVER THE CNTRL CONUS WAS DOMINATED BY A MID/UPPER LEVEL LOW OVER NW MO. UPSTREAM ANOTHER H5 LOW WAS LOCATED OVER SRN BC WILL HAVE WEATHER IMPACTS INTO THE CNTRL CONUS NEXT WEEK AS IT SLIDES EAST. AT THE SFC...WEAK NE FLOW PREVAILED OVER THE REGION BTWN LOW PRES OVER SRN IA AND A RIDGE FROM NE CANADA INTO NW MN. RADARS INDICATED A LARGE AREA OF MAINLY LIGHT RAIN FROM NE IA THROUGH CNTRL WI...CNTRL UPPER MI AND ERN LAKE SUPERIOR. THE PCPN WAS SUPPORTED BY A 850-700 MB FGEN/DEFORMATION AND 300K ISENTROPIC ASCENT ALONG AND NORTH OF THE 850 MB FRONT. MOISTURE FUNNELING INTO THE PCPN ZONE WAS ABUNDANT WITH THE 12Z KGRB SOUNDING SHOWING PWAT TO NEAR AN INCH. && .SHORT TERM (TONIGHT AND SATURDAY ISSUED AT 515 PM EDT)... ALTHOUGH THE MID LEVEL LOW IS FCST TO SLIDE TO THE ESE INTO THE OHIO VALLEY THE DEFORMATION ZONE PCPN INTO CNTRL UPPER MI IS EXPECTED TO PERSIST WITH ONLY A SLOW SHIFT INTO THE MAINLY THE W HALF OF THE CWA. OVER THE E HALF...MAINLY DRY WEATHER IS EXPECTED. THE FCST GENERALLY FOLLOWED A BLEND OF THE 12Z NAM/GFS AND LCL HIGH RES WRF WITH THE PCPN PATTERN/POPS AND QPF. WITH 850 MB TEMPS TO AROUND 10C...AND POTENTIAL FOR BETTER INSOLATION...TEMPS ARE EXPECTED TO CLIMB INTO THE LOWER 60S. OTHERWISE...THICKER CLOUDS AND PCPN WEST SHOULD LIMIT MAX READINGS CLOSER TO 50. MDLS SUGGEST THAT THE FORCING WILL WEAKEN SAT...SO THAT THE MODEST PCPN SHOULD TAPER OFF. OVERALL QPF VALUES SHOULD REMAIN IN THE 0.25 TO .50 INCH RANGE TONIGHT AND REMAIN BLO A 0.25 INCH SATURDAY. .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... THE CWA WILL BE IN A COL...WITH GENERAL HIGH PRESSURE BOTH SATURDAY AND SUNDAY...AS TWO 500MB LOWS AFFECT OTHER PORTIONS OF THE NATION. THE FIRST WILL SLIDE FROM THE MID MISSISSIPPI VALLEY TO THE MID OHIO VALLEY. THE SECOND LOW...CURRENTLY OVER THE COAST MOUNTAINS OF WESTERN BRITISH COLUMBIA WILL CONTINUE TO ROTATE ALONG THE PACIFIC NORTHWEST. SW FLOW WILL BEGIN AND STRENGTHEN SUNDAY NIGHT AS THE PACIFIC NORTHWEST TROUGH SLIDES TO CENTRAL SASKATCHEWAN TUESDAY AFTERNOON...AND THEN TO HUDSON BAY BY WEDNESDAY AFTERNOON. CONTINUE TO GO SLOWER THAN A DAY AGO...WITH NO SIGNIFICANT PRECIPITATION FIGURED SUNDAY AND MONDAY. THIS SW FLOW ALOFT WILL BRING ABOUT COOLER THAN NORMAL TEMPERATURES ALONG WITH AN INCREASED CHANCE FOR WET WEATHER THROUGH MID WEEK. ALONG AND JUST AHEAD OF THE COLD FRONT...THE POTENTIAL EXISTS FOR MODERATE TO HEAVY RAINFALL PARTICULARLY WITH ANY THUNDERSTORMS THAT DEVELOP...MAINLY TUESDAY MORNING THROUGH TUESDAY AFTERNOON...AS THE SURFACE LOW OVER THE SOUTHERN PLAINS TUESDAY MORNING SLIDES NORTHEASTWARD TO WESTERN LAKE SUPERIOR BY LATE TUESDAY AFTERNOON. THE COLD FRONT IS EXPECTED TO SLIDE EAST OF THE CWA SHORTLY AFTER MIDNIGHT TUESDAY NIGHT. WE WILL NEED TO CONTINUE TO MONITOR HIGH RUNNING RIVERS THROUGH THIS PERIOD...AS ADDITIONAL RAINFALL COULD POSE A THREAT TO ALREADY SWOLLEN RIVERS AND STREAMS. HIGH PRESSURE WILL SLIDE IN AT THE SFC ON WEDNESDAYS...STILL WITH A BROAD-SCALE TROUGH AT 500MB. INCREASED AFTERNOON HIGH TEMPS ABOUT 5 DEGREES FOR WEDNESDAY...AS COLDER AIR KEEPS NORTH OF THE AREA WITH 850MB TEMPERATURES NOT DIPPING BELOW 0C UNTIL THURSDAY EVENING. FOR TUESDAY THROUGH FRIDAY...HPC GUIDANCE WAS A BLEND OF THE 00Z ECMWF ENSEMBLE MEAN AND 00Z NCEP GLOBAL ENSEMBLE MEAN...WITH LESS WEIGHTING TO THE OPERATIONAL 06Z-12Z GFS/00Z ECMWF/00Z UKMET. && .HYDROLOGY... PCPN COMBINED WITH CONTINUED MILD TEMPS FOR SNOWMELT...READINGS AROUND 40F TONIGHT AND AROUND 50F SAT...WILL LEAD TO STEADY CLIMB IN RIVER LEVELS ESPECIALLY OVER THE WEST HALF. FOR CONTINUED UPDATES ON THE RIVERS...PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 00Z TAF ISSUANCE)... EXPECT CIGS TO DROP SLOWLY FROM MVFR TO IFR AT KCMX OVER THE NEXT FEW HRS AS A BAND OF -RA SETS UP OVER THE AREA. VIS SHOULD ALSO TREND DOWN INTO THE MVFR/IFR RANGE AS FOG DEVELOPS ALONG WITH THE OCCASIONAL -RA. EXPECT IMPROVING CONDITIONS LATE SAT MORNING INTO THE AFTN (VIS AND CIGS RISING TO VFR AND MVFR RESPECTIVELY) AS -RA DIMINISHES. -RA WILL GRADUALLY BE SHIFTING W OF KSAW DURING THE EVENING. ALTHOUGH -RA SHOULD END FOR THE MOST PART...EXPECT SOME FOG TO DEVELOP TO KEEP VIS MVFR/IFR...BUT TRENDING MORE PERSISTENTLY IFR DURING THE NIGHT. MEANWHILE...MOIST UPSLOPING NE WINDS SHOULD KEEP CIGS IFR/LIFR. EXPECT IMPROVING CONDITIONS LATE SAT MORNING WITH TREND TO VFR IN THE AFTN AS DRIER AIR SPREADS INTO THE AREA FROM THE E. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE GRADUALLY SHIFTS NORTHEAST OF LAKE SUPERIOR THROUGH SUNDAY...WITH WINDS AT OR LESS THAN 20KT. STRONGER SE WINDS UP TO 30 KT COULD OCCUR ON TUESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SYNOPSIS/SHORT TERM...JLB LONG TERM...KF HYDROLOGY...JLB AVIATION...ROLFSON MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 135 PM EDT FRI APR 18 2008 UPDATED FOR 18Z AVIATION DISCUSSION .UPDATE... RADARS INDICATED A LARGE AREA OF LIGHT TO MODERATE RAIN OVER SW AND CNTRL WI THAT WAS CONTINUING TO EXPAND INTO CNTRL UPPER MI. THE PCPN WAS SUPPORTED BY A 850-600 MB FGEN/DEFORMATION AND 300K ISENTROPIC ASCENT ALONG AND NORTH OF THE 850 MB FRONT. RADAR TRENDS AND THE 12Z NAM AND RUC SUGGEST THAT THE RAIN WILL PIVOT A BIT TO THE NORTHWEST WITH THE GREATEST COVERAGE FROM CNTRL OR W CNTRL UPPER MI. OVERALL AMOUNTS SHOULD REMAIN IN THE 0.10 TO 0.25 INCH RANGE WITH SOME LOCALIZED AMOUNTS TO AROUND A HALF INCH. && .DISCUSSION... UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW ACROSS CENTRAL KS EMBEDDED IN A TROUGH ACROSS THE PLAINS WITH RIDGING ACROSS THE EASTERN U.S. THERE IS A SHORTWAVE EMBEDDED IN THE TROUGH ACROSS SOUTHERN WI AND THIS SHORTWAVE HAS KICKED OFF SOME LIGHT RAIN ACROSS THE U.P. THIS EVENING. THIS SHORTWAVE HEADS NORTH OVERNIGHT WITH THE CLOSED LOW SLOWLY HEADING EAST ALONG WITH THE ASSOCIATED TROUGH. NAM SHOWING 850-500 MB Q-VECTOR CONVERGENCE ALONG WITH MOISTURE TODAY THROUGH SAT WITH THE CONVERGENCE WEAKENING LATE SAT INTO SUN WITH THE MOISTURE ALSO MOVING OUT LATE SAT NIGHT AND SUN. NAM SHOWING SOME ISENTROPIC LIFT ON I290K-I305K SURFACES OVERNIGHT WITH STRONG LIFT AND MOISTURE LASTING THROUGH TODAY. NAM SHOWS THE LOW LEVELS OVER THE EAST DRYING OUT TONIGHT WITH MOISTURE AND LIFT REMAINING OVER THE WEST HALF THROUGH SAT. GFS IS SIMILAR TO THE NAM WITH THE MOISTURE A BIT NARROWER AND LIFT ON I290K AND I300K NOT AS STRONG AS THE NAM. BASICALLY...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST. NAM AND GFS BOTH SHOW QPF AXIS SHIFTING WESTWARD WITH TIME TODAY AND HAD TO MOVE POPS A BIT FURTHER WEST TO ACCOUNT FOR HIGHER MOISTURE AND ISENTROPIC LIFT IN THE WEST. NAM AND GFS SHOW THIS SHIFTING TO THE WEST AND BOTH SHOW THE EAST DRYING OUT IN THE LOW LEVELS THIS AFTERNOON THROUGH SAT. WENT WITH THE LOWEST POPS THERE. OTHER CHANGE I DID IS REMOVE POPS ON SUN AND MON WITH NEXT SYSTEM DELAYED A BIT. WITH LESS POPS OVER THE EAST...RAISED TEMPERATURES A BIT. GOING TEMPERATURES LOOKED GOOD FOR THE MOST PART...BUT RAISED THEM A BIT FOR SUN AND MON WITH MORE SUNSHINE...LESS CLOUDS AND LESS PCPN. && .HYDROLOGY... (ISSUED AT 740 AM EDT) MOST RIVER LEVELS HAVE BEEN EITHER HOLDING OR CLIMBING THROUGH THE NIGHT...AND THIS TREND WILL CONTINUE INTO THE WEEKEND...ESPECIALLY ON THE SLOW RESPONSE RIVERS. RAINFALL DURING THE NIGHT OVER THE SOUTHEASTERN 1/2 OF THE U.P. HAS HELPED IN INCREASING THE RIVER LEVELS. A NEW PROBLEM APPEARS TO BE SHAPING UP...THOUGH...AND THAT IS A LARGE RAIN MASS OVER SW WI HEADING NORTHEAST. MODELS ARE DEPICTING THAT A WIDESPREAD 0.5 INCH OF QPF APPEARS LIKELY FROM THIS AFTERNOON WHEN THE RAIN MOVES IN...AND WHEN IT EXITS SATURDAY EVENING. HOWEVER...ISOLATED AMOUNTS OF 1 TO 1.5 INCHES ARE INDICATED IN THE LATEST HIGH RESOLUTION RUNS. THIS ADDITIONAL RAINFALL COULD CAUSE SOME OF THE SHORT RESPONSE RIVERS TO GO ABOVE FLOOD STAGE. AFTER THIS RAIN...A TRANSITION TO ALMOST EARLY SUMMERTIME WEATHER APPEARS TO BE IN STORE...FOLLOWED BY A COLD FRONTAL PASSAGE ON TUESDAY THAT COULD BE ACCOMPANIED BY THUNDERSTORMS WITH HEAVY RAINFALL. IMAGINE THAT THE RAIN COMBINED WITH THE UPCOMING WARMUP WILL MELT MOST IF NOT ALL THE SNOW ACROSS UPPER MI. THEREFORE... MANY RIVERS ARE EXPECTED TO REMAIN HIGH THROUGH MUCH OF NEXT WEEK...ESPECIALLY THE SLOW RESPONDING RIVERS SUCH AS THE MICHIGAMME. CURRENT RIVERS OF IMMEDIATE CONCERN THAT ARE BEING WATCHED INCLUDE THE TRAP ROCK RIVER NEAR LAKE LINDEN...THE STURGEON RIVER NEAR ALSTON AND THE CHOCOLAY RIVER NEAR HARVEY. ALL THREE OF THESE HAVE POTENTIAL FOR BRIEFLY TOUCHING FLOOD STAGE. THE STURGEON RIVER NEAR ALSTON DEPENDS HIGHLY ON THE FLOW OUT OF PRICKETT DAM...WHICH IF THE HIGHER QPF VALUES MENTIONED EARLIER PAN OUT...THE RIVER IS LIKELY TO GO ABOVE FLOOD STAGE. NEXT RIVERS OF CONCERN BUT REACHING NEAR FLOOD STAGE MAY TAKE A LITTLE LONGER INCLUDE THE STURGEON RIVER NEAR NAHMA JUNCTION AND THE TAHQUAMENON RIVER NEAR UPPER FALLS. FOR THE SLOW RESPONSE RIVERS...THOSE THAT ARE BEING WATCHED INCLUDE THE EAST BRANCH OF THE ESCANABA RIVER AT GWINN AND THE MICHIGAMME RIVER NEAR WITCH LAKE AND REPUBLIC. FINALLY...THE MANISTIQUE RIVER NORTHEAST OF MANISTIQUE REMAINS ABOVE BANKFULL...BUT ITS IMPACTS ARE MINOR IF ANY. FOR CONTINUED UPDATES ON THE RIVERS...PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... EXPECT CIGS TO GRADUALLY COME DOWN AT BOTH SITES WITH RAIN OVER CNTRL UPPER MI SPREADING SLOWLY TO THE NW ...THOUGH MORE QUICKLY AT SAW WITH AN UPSLOPE NE WIND. IMAGINE THAT BY EARLY EVENING...SAW SHOULD HAVE IFR CIGS. IT IS POSSIBLE THAT SAW COULD GO LOWER...BUT UNCERTAINTIES EXIST ON HOW MOIST THE UPSLOPE NE FLOW WILL BE. AT CMX...THE NE WIND IS NOT NEARLY AS FAVORABLE FOR LOWER CIGS...AND THEREFORE HAVE KEPT CIGS AT MVFR UNTIL LATE EVENING. BOTH SITES SHOULD EXPERIENCE IFR VISIBILITIES OVERNIGHT INTO EARLY SATURDAY. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE GRADUALLY SHIFTS NORTHEAST OF LAKE SUPERIOR THROUGH SUNDAY...WITH WINDS AT OR LESS THAN 20KT. STRONGER SE WINDS UP TO 30 KT COULD OCCUR ON TUESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLB DISCUSSION...GJM HYDROLOGY...AJ AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1140 AM EDT FRI APR 18 2008 .UPDATE... RADARS INDICATED A LARGE AREA OF LIGHT TO MODERATE RAIN OVER SW AND CNTRL WI THAT WAS CONTINUING TO EXPAND INTO CNTRL UPPER MI. THE PCPN WAS SUPPORTED BY A 850-600 MB FGEN/DEFORMATION AND 300K ISENTROPIC ASCENT ALONG AND NORTH OF THE 850 MB FRONT. RADAR TRENDS AND THE 12Z NAM AND RUC SUGGEST THAT THE RAIN WILL PIVOT A BIT TO THE NORTHWEST WITH THE GREATEST COVERAGE FROM CNTRL OR W CNTRL UPPER MI. OVERALL AMOUNTS SHOULD REMAIN IN THE 0.10 TO 0.25 INCH RANGE WITH SOME LOCALIZED AMOUNTS TO AROUND A HALF INCH. && .DISCUSSION... UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW ACROSS CENTRAL KS EMBEDDED IN A TROUGH ACROSS THE PLAINS WITH RIDGING ACROSS THE EASTERN U.S. THERE IS A SHORTWAVE EMBEDDED IN THE TROUGH ACROSS SOUTHERN WI AND THIS SHORTWAVE HAS KICKED OFF SOME LIGHT RAIN ACROSS THE U.P. THIS EVENING. THIS SHORTWAVE HEADS NORTH OVERNIGHT WITH THE CLOSED LOW SLOWLY HEADING EAST ALONG WITH THE ASSOCIATED TROUGH. NAM SHOWING 850-500 MB Q-VECTOR CONVERGENCE ALONG WITH MOISTURE TODAY THROUGH SAT WITH THE CONVERGENCE WEAKENING LATE SAT INTO SUN WITH THE MOISTURE ALSO MOVING OUT LATE SAT NIGHT AND SUN. NAM SHOWING SOME ISENTROPIC LIFT ON I290K-I305K SURFACES OVERNIGHT WITH STRONG LIFT AND MOISTURE LASTING THROUGH TODAY. NAM SHOWS THE LOW LEVELS OVER THE EAST DRYING OUT TONIGHT WITH MOISTURE AND LIFT REMAINING OVER THE WEST HALF THROUGH SAT. GFS IS SIMILAR TO THE NAM WITH THE MOISTURE A BIT NARROWER AND LIFT ON I290K AND I300K NOT AS STRONG AS THE NAM. BASICALLY...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST. NAM AND GFS BOTH SHOW QPF AXIS SHIFTING WESTWARD WITH TIME TODAY AND HAD TO MOVE POPS A BIT FURTHER WEST TO ACCOUNT FOR HIGHER MOISTURE AND ISENTROPIC LIFT IN THE WEST. NAM AND GFS SHOW THIS SHIFTING TO THE WEST AND BOTH SHOW THE EAST DRYING OUT IN THE LOW LEVELS THIS AFTERNOON THROUGH SAT. WENT WITH THE LOWEST POPS THERE. OTHER CHANGE I DID IS REMOVE POPS ON SUN AND MON WITH NEXT SYSTEM DELAYED A BIT. WITH LESS POPS OVER THE EAST...RAISED TEMPERATURES A BIT. GOING TEMPERATURES LOOKED GOOD FOR THE MOST PART...BUT RAISED THEM A BIT FOR SUN AND MON WITH MORE SUNSHINE...LESS CLOUDS AND LESS PCPN. && .HYDROLOGY... (ISSUED AT 740 AM EDT) MOST RIVER LEVELS HAVE BEEN EITHER HOLDING OR CLIMBING THROUGH THE NIGHT...AND THIS TREND WILL CONTINUE INTO THE WEEKEND...ESPECIALLY ON THE SLOW RESPONSE RIVERS. RAINFALL DURING THE NIGHT OVER THE SOUTHEASTERN 1/2 OF THE U.P. HAS HELPED IN INCREASING THE RIVER LEVELS. A NEW PROBLEM APPEARS TO BE SHAPING UP...THOUGH...AND THAT IS A LARGE RAIN MASS OVER SW WI HEADING NORTHEAST. MODELS ARE DEPICTING THAT A WIDESPREAD 0.5 INCH OF QPF APPEARS LIKELY FROM THIS AFTERNOON WHEN THE RAIN MOVES IN...AND WHEN IT EXITS SATURDAY EVENING. HOWEVER...ISOLATED AMOUNTS OF 1 TO 1.5 INCHES ARE INDICATED IN THE LATEST HIGH RESOLUTION RUNS. THIS ADDITIONAL RAINFALL COULD CAUSE SOME OF THE SHORT RESPONSE RIVERS TO GO ABOVE FLOOD STAGE. AFTER THIS RAIN...A TRANSITION TO ALMOST EARLY SUMMERTIME WEATHER APPEARS TO BE IN STORE...FOLLOWED BY A COLD FRONTAL PASSAGE ON TUESDAY THAT COULD BE ACCOMPANIED BY THUNDERSTORMS WITH HEAVY RAINFALL. IMAGINE THAT THE RAIN COMBINED WITH THE UPCOMING WARMUP WILL MELT MOST IF NOT ALL THE SNOW ACROSS UPPER MI. THEREFORE... MANY RIVERS ARE EXPECTED TO REMAIN HIGH THROUGH MUCH OF NEXT WEEK...ESPECIALLY THE SLOW RESPONDING RIVERS SUCH AS THE MICHIGAMME. CURRENT RIVERS OF IMMEDIATE CONCERN THAT ARE BEING WATCHED INCLUDE THE TRAP ROCK RIVER NEAR LAKE LINDEN...THE STURGEON RIVER NEAR ALSTON AND THE CHOCOLAY RIVER NEAR HARVEY. ALL THREE OF THESE HAVE POTENTIAL FOR BRIEFLY TOUCHING FLOOD STAGE. THE STURGEON RIVER NEAR ALSTON DEPENDS HIGHLY ON THE FLOW OUT OF PRICKETT DAM...WHICH IF THE HIGHER QPF VALUES MENTIONED EARLIER PAN OUT...THE RIVER IS LIKELY TO GO ABOVE FLOOD STAGE. NEXT RIVERS OF CONCERN BUT REACHING NEAR FLOOD STAGE MAY TAKE A LITTLE LONGER INCLUDE THE STURGEON RIVER NEAR NAHMA JUNCTION AND THE TAHQUAMENON RIVER NEAR UPPER FALLS. FOR THE SLOW RESPONSE RIVERS...THOSE THAT ARE BEING WATCHED INCLUDE THE EAST BRANCH OF THE ESCANABA RIVER AT GWINN AND THE MICHIGAMME RIVER NEAR WITCH LAKE AND REPUBLIC. FINALLY...THE MANISTIQUE RIVER NORTHEAST OF MANISTIQUE REMAINS ABOVE BANKFULL...BUT ITS IMPACTS ARE MINOR IF ANY. FOR CONTINUED UPDATES ON THE RIVERS...PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... RAIN THAT AFFECTED SAW EARLIER IN THE NIGHT HAS SHIFTED TO THE SE ALONG LAKE MICHIGAN. HOWEVER...ANOTHER LARGE RAIN MASS COVERING NE IOWA...FAR SE MN AND SW WI IS HEADING NORTHEAST TOWARDS THE WEST HALF OF UPPER MI. EXTRAPOLATING THE RAIN NORTHEAST AND COMPARING TO MODELS WOULD HAVE IT IMPACTING THE TAF SITES THIS AFTN AND TONIGHT. IT IS POSSIBLE THAT THE RAIN COULD SHIFT JUST WEST OUT OF SAW THIS EVENING...BUT CONFIDENCE IS LOW IN THIS OCCURRING. EXPECTING CIGS TO GRADUALLY COME DOWN AT BOTH SITES...THOUGH QUICKER AT SAW WITH AN UPSLOPING NE WIND. IMAGINE THAT BY EARLY EVENING...SAW SHOULD HAVE IFR CIGS. IT IS POSSIBLE THAT SAW COULD GO LOWER...BUT UNCERTAINTIES EXIST ON HOW MOIST THE UPSLOPE NE FLOW WILL BE. AT CMX...THE NE WIND IS NOT NEARLY AS FAVORABLE FOR LOWER CIGS...AND THEREFORE HAVE KEPT CIGS AT MVFR. BOTH SITES SHOULD EXPERIENCE IFR VISIBILITIES...THOUGH. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE GRADUALLY SHIFTS NORTHEAST OF LAKE SUPERIOR THROUGH SUNDAY...WITH WINDS AT OR LESS THAN 20KT. STRONGER SE WINDS UP TO 30 KT COULD OCCUR ON TUESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLB DISCUSSION...GJM HYDROLOGY...AJ AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 128 AM EDT FRI APR 18 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .UPDATE (ISSUED AT 1026 PM EDT)... MAIN FCST ISSUE OVERNIGHT IS -RA COVERAGE. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A STRONG SHORTWAVE MOVING E INTO THE SRN PLAINS. DOWNSTREAM RIDGING COMBINED WITH A MORE ZONAL FLOW OVER SRN CANADA IS RESULTING IN UPPER JET STREAK EXTENDING FROM LAKE SUPERIOR/ONTARIO EWD. UPPER DIVERGENCE IN THE RIGHT ENTRANCE OF JET AND CORRESPONDING BAND OF MIDLEVEL FRONTOGENESIS IS SUPPORTING PCPN THAT IS STREAKING NE FROM THE SRN PLAINS SHORTWAVE INTO THE UPPER LAKES REGION. PCPN HAS NOT BEEN WELL ORGANIZED YET AS ABUNDANT LOW-LEVEL DRY AIR IS PRESENT OVER UPPER MI PER LATE AFTN TAMDAR SOUNDINGS FROM KSAW/KCMX. IT IS ONLY WHERE FORCING IS WELL FOCUSED THAT PCPN HAS OVERCOME DRY AIR. SO FAR THAT AREA EXISTS FROM ABOUT WATERSMEET AND KIMT NE TO KMQT. POSITION OF UPPER JET AND 700-600MB FRONTOGENESIS OVERNIGHT SUGGESTS THAT THE AREA WHERE SOME -RA IS CURRENTLY OCCURRING MAY BE THE AREA WHERE PCPN REMAINS MOST PERSISTENT THRU THE NIGHT. SO WILL BUMP POPS UP ACROSS ERN IRON/DICKINSON/ERN BARAGA/MARQUETTE COUNTIES OVERNIGHT. STILL EXPECT THE FAR W TO REMAIN DRY. LARGER BATCH OF -RA THAT HAS DEVELOPED IN ERN IA/NW IL/SW WI WILL LIKELY AFFECT THE SE AND E FCST AREA LATER IN THE NIGHT...SUPPORTING PREVIOUS FCST OF CATEGORICAL POPS FOR MOST OF THAT AREA. && .SHORT TERM (TONIGHT AND FRIDAY)... ISSUED AT 435 PM EDT PLENTY OF MID TO HIGH CLOUDS ARE ROLLING IN...AHEAD OF THE NEXT BATCH OF PRECIPITATION HEADING OUR WAY. AT 1930Z...RADAR WAS INDICATING RAIN WITH ISOLATED THUNDERSTORM ACTIVITY OVER SOUTHEASTERN MINNESOTA...WITH RAIN STRETCHING THROUGH CENTRAL WISCONSIN. THIS PRECIPITATION WAS ASSOCIATED WITH THE ELONGATED AREA OF LOW PRESSURE STRETCHING FROM QUEBEC DOWN THROUGH UPPER LOWER MICHIGAN...TO SOUTHERN IOWA AND CENTRAL KANSAS. THE MAIN CONCERN OVERNIGHT THROUGH THE DAY FRIDAY AND BEYOND IS PRECIPITATION AMOUNTS...AND HOW THIS WILL AFFECT ALREADY SWOLLEN RIVERS ACROSS UPPER MICHIGAN. THE NAM...IN ITS 12Z RUN HAS BECOME MORE AGGRESSIVE IN ALLOWING MOISTURE TO OVERCOME THE RIDGE OVER SE CANADA. THIS IS MORE IN LINE WITH THE 06Z AND 12Z GFS RUNS. THE CANADIAN REMAINS STILL A LITTLE MORE TO THE SE WITH PRECIPITATION...KEEPING A MAJORITY OVER EASTERN OR EAST OF UPPER MICHIGAN. WILL HEDGE THE FORECAST TOWARDS THE MORE AGGRESSIVE PRECIPITATION SLIDING MORE INTO CENTRAL UPPER MICHIGAN. EVEN THOUGH PRECIPITATION IS LIKELY...EXPECT ONLY LIGHT PRECIPITATION DURING THE EARLY TO MID AFTERNOON HOURS FRIDAY. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) FRI NIGHT THROUGH SUN..THE 12Z NAM...GFS AND CANADIAN REGIONAL GEM HAVE CONTINUED TREND TOWARD SPREADING PCPN FARTHER NW THROUGH MUCH OF UPPER MI. THE PCPN WILL BE SUPPORTED BY UPPER LEVEL WITH 250-300 JET INTO NRN ONTARIO AND BAND OF 800-600 MB DEFORMATION/FGEN WELL TO THE NORTH OF THE 500 MB LOW TRACKING THROUGH THE OH VALLEY. THE FCST AGAIN LEANED MORE TOWARD THE CANADIAN REGIONAL GEM WHICH WAS SUPPORTED BY THE UKMET AND ECMWF IN LIMITING THE WESTWARD EXTENT OF THE PCPN BAND. HOWEVER...GIVEN THE MODEL DIFFERENCES CONSIDERABLE UNCERTAINTY REMAINS REGARDING RAIN POTENTIAL/COVERAGE AS IT IS POSSIBLE THAT THE PCPN BAND MAY PUSH FAR ENOUGH OF TO THE WEST...PER NAM...SO THAT THE SE CWA MAY SEE LITTLE PCPN. ONLY A SLIGHT CHANCE FOR PCPN OR SPRINKLES INCLUDED BY SUNDAY AS THE DEFORMATION ZONE WEAKENS. MON-THU...THE MODELS WERE CONSISTENT WITH THE DEVELOPMENT OF A NW CONUS MID LEVEL LOW THAT SLOWLY MOVES TOWARD S CNTRL CANADA. GIVEN THE BLOCKY NATURE OF THE PATTERN AND THE TREND OF 12Z GFS...THE SLOWER FRONTAL MOVEMENT AND FARTHER N POSITION OF THE MID LEVEL LOW DEPICTED BY THE 00Z ECMWF WAS PREFERRED. SO...THE BEST CHANCE FOR PCPN IS EXPECTED MON NIGHT LINGERING INTO TUE AS THE MAIN FRONTAL BOUNDARY MOVES THROUGH THE REGION. 850 MB DEWPOINT AROUND 10C AND LI AROUND 0 STILL SUPPORT POTENTIAL FOR ISOLD TSRA WITH THE SYSTEM. CAA BRINGS IN ENOUGH COLD AIR WITH WRAP-AROUND MOISTURE FOR POSSIBILITY OF SCT RA/SN SHOWERS. && .HYDROLOGY... CONTINUE TO MONITOR RIVER LEVELS...AS RIVERS RISE DUE TO ONGOING SNOW MELT. WILL NEED TO CONTINUE TO CLOSELY WATCH THEM AND THEIR RESPONSE TO ADDITIONAL WATER DUE TO RAINFALL EXPECTED THROUGH SATURDAY NIGHT. AT THE CURRENT TIME...SEVERAL RIVERS ARE EXPECTED TO RUN HIGH...BUT BELOW FLOOD STAGE. SOME LOCATIONS OF NOTE INCLUDE THE EAST BRANCH OF THE ESCANABA RIVER AT GWINN...THE STURGEON RIVER DOWNSTREAM OF PRICKETT DAM AND UPSTREAM OF NAHMA JUNCTION...THE MICHIGAMME RIVER NEAR WHICH LAKE AND REPUBLIC...THE TRAP ROCK RIVER NEAR LAKE LINDEN...THE TAHQUAMENON RIVER NEAR UPPER FALLS...THE CHOCOLAY RIVER NEAR HARVEY...THE STAND THE MANISTIQUE RIVER NORTHEAST OF MANISTIQUE. SEE THE LATEST HYDROLOGIC STATEMENT FOR FURTHER DETAILS. FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... WAVES OF -RA WILL BE LIFTING NE INTO THE UPPER GREAT LAKES REGION DURING THIS FCST PERIOD. AT THIS TIME...IT APPEARS KCMX WILL BE NW OF THE -RA THRU MUCH OF THIS FCST PERIOD WITH CONDITIONS REMAINING VFR. INTRODUCED -RA INTO FCST IN THE EVENING...BUT STILL EXPECT VFR CONDITIONS DUE TO INITIAL LOW-LEVEL DRY AIR. AT KSAW...-RA HAS DEVELOPED QUICKER THAN EXPECTED DESPITE PRESENCE OF DRY AIR AT THE LOW-LEVELS. STILL...IT PROBABLY WON`T BE UNTIL MID MORNING THAT LOW-LEVELS MOISTEN SIGNIFICANTLY TO RESULT IN DEVELOPMENT OF MVFR CIGS. THERE MAY BE SOME MVFR VIS IN -RA PRIOR TO MVFR CIGS. ALTHOUGH THERE COULD BE A BREAK IN THE -RA FOR SEVERAL HRS IN THE AFTN...CIGS SHOULD REMAIN MVFR. CIGS AND VIS ARE EXPECTED TO FALL INTO THE IFR RANGE IN THE EVENING UNDER INCREASINGLY MOIST UPSLOPING NE WINDS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE GRADUALLY SHIFTS NORTHEAST OF THE AREA...WITH WINDS AT OR LESS THAN 20KT. STRONGER SE WINDS...BUT STILL AOB 25 KT COULD OCCUR LATE MONDAY ON EASTERN LAKE SUPERIOR AHEAD OF A COLD FRONT APPROACHING FROM THE PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SHORT TERM...KF LONG TERM...JLB HYDROLOGY...KF AVIATION...ROLFSON MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 536 PM CDT SAT APR 19 2008 .DISCUSSION... LOW PRESSURE CONTINUES TO DRIFT SLOWLY EASTWARD ACROSS THE LOWER GREAT LAKES. A FEW SHOWERS HAVE DEVELOPED THIS AFTERNOON ACROSS THE WI CWA ALONG A TROF AXIS. HELPING MATTERS IS STRONG HEATING THAT HAS DEVELOPED TO THE EAST AND SOUTH OF KEAU WITH SOME CLEARING. THERMAL GRADIENT ACROSS THE WESTERN HALF OF WI ABOUT 20 DEGREES ATTM. RUC BEST LI INTO THE EVENING AROUND ZERO SO WILL MENTION A FEW SHOWERS AND ISOLATED THUNDER THROUGH THE EVENING. NEXT CONCERN IS FOG POTENTIAL OVERNIGHT. BELIEF IS THAT THE LOW LEVEL FLOW WILL BECOME MORE EASTERLY OVERNIGHT DRAGGING SOME OF THE LOW CLOUDS INTO THE WESTERN CWA WHILE MAINTAINING A GOOD DEAL OF CLOUDINESS ELSEWHERE. DUE TO THE RAINS OVER WI AND SOUTH CENTRAL AREAS OF MN...AREAS OF FOG SHOULD OCCUR AGAIN TONIGHT. HOWEVER..IT COULD BECOME DENSE IF THE LOW CLOUDS WOULD DIMINISH DURING THE NIGHT. THIS LEADS INTO SUNDAY ON HOW HIGH AFTERNOON TEMPERATURES WILL GET IF PARTLY TO MOSTLY CLOUDY SKIES PREVAIL. NAM CU RULE IS QUITE NEGATIVE OVER EASTERN MN AND WEST CENTRAL WI...SO CUT BACK A LITTLE ON THE HIGH TEMPERATURES OVER THE EASTERN HALF OF THE CWA. THINGS REMAIN PRETTY MUCH ON TRACK WITH LOW PRESSURE AND A COLD FRONT APPROACHING WESTERN MN SUNDAY NIGHT AND THEN MOVING TO NEAR THE MN/WI BORDER BY MONDAY NIGHT. MAIN CHANGES TODAY WERE TO TIGHTEN UP ON THE POPS AND KEEP THEM CONFINED TO THE FAR WEST SUNDAY NIGHT WHERE SOME ELEVATED INSTABILITY DEVELOPS AND THEN NOT ALLOW THINGS TO GET TO FAR TO THE EAST TOO FAST ON MONDAY. STILL LOOKS GOOD FOR SHOWERS AND THUNDERSTORMS ALONG THE FRONT...ESPECIALLY EASTERN MN LATE MONDAY AFTERNOON AND EVENING AND THEN SPREADING INTO WI DURING THE NIGHT. THE FRONT BECOMES NEARLY STATIONARY ACROSS WEST CENTRAL WI BY TUESDAY MORNING AS LOW PRESSURE BEGINS TO RIDE NORTHEAST ALONG THE FRONT. PRECIPITATION CHANCES REMAIN HIGH OVER THE EASTERN CWA UNTIL TUESDAY EVENING. CAPE VALUES MODEST ON MONDAY AND LOW LEVEL SHEAR IS DIMINISHING MONDAY AFTERNOON. WHAT IS REALLY INTERESTING IS THE COUPLED JET THAT DEVELOPS ACROSS OUR AREA MONDAY NIGHT AND TUESDAY...GIVING THE EASTERN CWA QUITE A BIT OF DIFFERENTIAL LAYER DIVERGENCE. THIS WILL BE A PERIOD THAT WILL NEED TO BE MONITORED NOT ONLY FOR SEVERE WEATHER BUT HEAVY RAINFALL. A BREAK IN THE RAIN ON WEDNESDAY AS HIGH PRESSURE MOVES BY THEN A MORE VIGOROUS LOW WILL BE MOVING IN FROM THE CENTRAL PLAINS THURSDAY AND FRIDAY WITH SOME PRETTY GOOD APRIL SHOWERS AND THUNDERSTORMS. && .AVIATION.../00Z TAF ISSUANCE/ TAMDAR SOUNDINGS FROM AIRCRAFT IN AND OUT OF MSP STILL REVEALING A SEVERAL THOUSAND FEET THICK LOW LEVEL MOISTURE LAYER. SOUNDINGS OUT OF EAU AIRPORT SHOW LESS DEPTH TO THE MOISTURE AND VISIBLE SATELLITE CHANNEL IS INDEED PORTRAYING WHOLES IN THE CLOUD COVER NEAR EAU. CONDITIONS WILL LIKELY GO SCT THERE AT TIMES THIS EVE. THIS WILL SET THE STAGE FOR FOG NEAR EAU THAT MAY LAST INTO THE POST DAYBREAK HOURS ON SUN. MSP...RNH...AND STC MORE LIKELY TO STAY UNDER MVFR/IFR STRATUS. LOW T/TDS SPREADS WILL LIKELY PRESENT AT LEAST SOME MVFR VISBYS OVERNIGHT. OUT WEST...AXN AND RWF WILL FEEL THE EFFECT OF THE LOW CLOUDS TONIGHT AS THEY BEGIN TO BE CAUGHT IN THE RETURN FLOW AND RETROGRADE WESTWARD. CONDITIONS MORE LIKELY TO STAY MVFR AT THESE SITES. DURING SUNDAY THE CLOUDS SHOULD BE SLOW TO BREAK IN THE MORNING AS LOW LEVEL WIND GRADIENT IS SOMEWHAT LAX. BUT IN THE AFTN A MORE RAPID SCATTERING IS LIKELY. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/MTF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1244 PM CDT SAT APR 19 2008 .UPDATE...FOR 18Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 355 AM CDT SAT APR 19 2008/ EARLY MORNING WATER VAPOR IMAGERY SHOWS CUTOFF UPPER LOW CONTINUING TO SPIN OVER THE MID MISSISSIPPI RIVER VALLEY AND DRIFTING EAST. THE TROUGH HAS TAKEN ON A NEGATIVE TILT THROUGH THE EVENING WITH 295 K SFC SHOWING UPGLIDE INTO WEST CENT WI AND EAST CENT MN EARLY THIS MORNING. RADAR CONTINUES TO SHOW BANDS OF LIGHT RAIN ROTATING NORTHWESTWARD. THE BACK EDGE OF THE BAND HAS BEGUN TO DRIFT BACK EASTWARD AFTER A WESTWARD MARCH LATE LAST NIGHT WITH RUC 295 K DATA INDICATING THAT THIS TREND WILL CONTINUE. HAVE KEPT LOW POPS ACROSS EAST CENT MN THROUGH THE MORNING WITH THE LOW CONTINUING TO HAVE INFLUENCE WITH HIGHER CHANCE POPS IN WISCONSIN AS RAIN SHIELD PULLS BACK EAST. DECIDED TO KEEP SLIGHT POPS IN FAR EAST CENT MN...INCLUDING MUCH OF THE TWIN CITIES METRO THIS AFTERNOON WITH MID LEVEL LAPSE RATES STEEPENING AND POTENTIAL FOR SOME BREAKS IN THE CLOUD COVER SUPPORTING SMALL CHANCE FOR SHOWER DEVELOPMENT. KEPT PARTLY TO MOSTLY CLOUD SKIES ACROSS THE MN COUNTIES TODAY WITH LOW LEVEL FLOW CONTINUING TO PUSH CLOUD COVER WESTWARD BUT DRIER AIR WILL BEGIN TO WIN OUT HELPING TO DECREASE THE CLOUD OVERAGE FROM WEST TO EAST ACROSS WEST CENT MN. TEMPERATURES WILL BE VERY DEPENDENT ON BREAKING UP OF CLOUDS. THE WEST AND NORTHWEST SHOULD REACH THE LOWER 60S WITH THE EAST CENT MN COUNTIES IN THE UPPER 50S TO NEAR 60 WITH MORE ABUNDANT CLOUD COVER...AND WEST CENT WI REACHING THE LOW TO MID 50S WITH CONTINUED CLOUDS AND SHOWERS. HIGH PRESSURE BUILDS IN TONIGHT WITH WEAK SFC FLOW TAKING HOLD. ADDED FOG FOR MUCH OF THE EASTERN CWA GIVEN THE RAINFALL AND DECREASING WINDS. INTERESTING WEATHER CONTINUES INTO EARLY NEXT WEEK AS CUTOFF UPPER LOW SPINS EASTWARD ACROSS THE APPALACHIANS AND BROAD CLOSED OFF UPPER LOW CURRENTLY OVER THE WASHINGTON STATE/BRITISH COLUMBIA BORDER TAKES RESIDENCE OVER MUCH OF THE NORTHWEST U.S. AS OMEGA BLOCK SETS UP OVER THE EASTERN PACIFIC. LOCALLY...THIS SETS UP SOUTHERLY UPPER LEVEL FLOW WITH SFC LOW PRESSURE BECOMING ESTABLISHED TO THE WEST OVER THE HIGH PLAINS UNDER UPPER HEIGHT FALLS. THIS WILL ALLOW SOUTHERLY SFC FLOW TO TAKE OVER INTO SUNDAY AND CONTINUE THROUGH MONDAY WITH MID LEVEL WARMTH BUILDING OVERHEAD AS EVIDENCED BY +10 TO +12 H85 TEMPS. THIS WILL ALLOW A NICE WARM UP INTO THE UPPER 60S TO AROUND 70 SUNDAY AND MONDAY. A FRONTAL BOUNDARY WILL APPROACH MONDAY WITH ADDITIONAL WARMING THROUGH COMPRESSIONAL HEATING POSSIBLE SO WILL NEED TO WATCH TEMPS MONDAY. WITH THE UPPER LOW STILL HANGING BACK WELL TO THE WEST MONDAY THE FRONT WILL TAKE ITS TIME CROSSING THE AREA. THE UPPER LOW THEN BEGINS TO KICK NORTHEAST INTO CENTRAL CANADA AS A LOW UNDERCUTS THE PACIFIC OMEGA RIDGE ALLOWING EVOLUTION INTO A REX PATTERN TO TAKE PLACE. THE LOCAL RESULT IS SFC CYCLOGENESIS OVER THE UPPER MISSISSIPPI RIVER VALLEY BY EARLY TUESDAY SENDING STRENGTHENING SFC LOW NORTHWARD ACROSS EASTERN MN TUESDAY MORNING. SHOWERS AND THUNDERSTORMS ARE EXPECT TO DEVELOP AS EARLY AS MONDAY MORNING ACROSS WEST-CENTRAL MINNESOTA AS FRONT APPROACHES WITH BETTER CHANCES ARRIVING MONDAY EVENING AS SFC LOW INTENSIFIES. NAM-WRF IS SHOWING STRONGER INSTABILITY AT THIS POINT WITH CAPE VALUES EXCEEDING 1000 J/KG AND BEST COLUMN LI/S OF -4 WITH STRONGER MOISTURE ADVECTION THAN THE GFS. PWAT INCREASES OF MORE THAN A QUARTER INCH IN 6 HOURS ALSO APPEAR MONDAY EVENING. THE EASTWARD PROGRESS OF THE FRONT SLOWS TUESDAY MORNING AS THE SFC LOW MOVES NORTHWARD ALONG IT ALLOWING A LONGER PERIOD OF SHOWERS AND THUNDERSTORMS ACROSS EAST CENT MN AND WEST CENT WI. SFC HIGH PRESSURE SETTLES TO THE WEST INTO WEDNESDAY BUT SEVERAL SHORTWAVES TRAVERSE THE AREA KEEPING A LOW CHANCE FOR ADDITIONAL SHOWERS BUT DRY CONDITIONS LOOK TO FILL IN DURING THE DAY WEDNESDAY WITH HIGH PRESSURE TO THE SOUTH. COOLER AIR WILL ALSO ARRIVE WITH H85 TEMPS BACK BELOW ZERO. BRIEF ZONAL FLOW OF AIR IN THE MID LEVELS KEEPS THINGS QUIET INTO WEDNESDAY NIGHT BUT THERE ARE INDICATIONS OF UPPER FLOW TRYING TO BUCKLE WITH ANOTHER SFC LOW APPROACHING FROM THE WEST. WARM AIR ADVECTION COMMENCES THURSDAY MORNING WITH ENOUGH MOISTURE IN PLACE BY THAT TIME TO SUPPORT PRECIP CHANCES ONCE AGAIN. ..MDB.. && .AVIATION.../18Z TAF ISSUANCE/ LOW CLOUDS CONTINUE TO PLAGUE ALL TAF SITES BUT KAXN THIS AFTERNOON. ALTHOUGH EXPECT KSTC/KRWF TO SEE A FEW BREAKS IN THE CLOUDS THIS AFTERNOON...MVFR CEILINGS WILL REMAIN ENTRENCHED AT KMSP/KRNH/KEAU...WHICH IS SUPPORTED BY THE NAM 925 MB RH PROGS. CEILINGS WILL DEGRADE FURTHER THIS EVENING/TONIGHT...WITH IFR CONDITIONS EXPECTED TO DEVELOP AT ALL SITES AFTER MIDNIGHT. AREAS OF FOG ARE ALSO LIKELY...WITH WIDESPREAD VISIBILITIES BETWEEN 1 AND 3 MPH EXPECTED. CONDITIONS WILL LIKELY NOT BEGIN IMPROVING INTO THE VFR CATEGORY UNTIL AROUND/AFTER 15Z SUNDAY...AS THE WINDS PICK UP ABOVE 10 KNOTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/MDB mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 715 AM CDT SAT APR 19 2008 .DISCUSSION... EARLY MORNING WATER VAPOR IMAGERY SHOWS CUTOFF UPPER LOW CONTINUING TO SPIN OVER THE MID MISSISSIPPI RIVER VALLEY AND DRIFTING EAST. THE TROUGH HAS TAKEN ON A NEGATIVE TILT THROUGH THE EVENING WITH 295 K SFC SHOWING UPGLIDE INTO WEST CENT WI AND EAST CENT MN EARLY THIS MORNING. RADAR CONTINUES TO SHOW BANDS OF LIGHT RAIN ROTATING NORTHWESTWARD. THE BACK EDGE OF THE BAND HAS BEGUN TO DRIFT BACK EASTWARD AFTER A WESTWARD MARCH LATE LAST NIGHT WITH RUC 295 K DATA INDICATING THAT THIS TREND WILL CONTINUE. HAVE KEPT LOW POPS ACROSS EAST CENT MN THROUGH THE MORNING WITH THE LOW CONTINUING TO HAVE INFLUENCE WITH HIGHER CHANCE POPS IN WISCONSIN AS RAIN SHIELD PULLS BACK EAST. DECIDED TO KEEP SLIGHT POPS IN FAR EAST CENT MN...INCLUDING MUCH OF THE TWIN CITIES METRO THIS AFTERNOON WITH MID LEVEL LAPSE RATES STEEPENING AND POTENTIAL FOR SOME BREAKS IN THE CLOUD COVER SUPPORTING SMALL CHANCE FOR SHOWER DEVELOPMENT. KEPT PARTLY TO MOSTLY CLOUD SKIES ACROSS THE MN COUNTIES TODAY WITH LOW LEVEL FLOW CONTINUING TO PUSH CLOUD COVER WESTWARD BUT DRIER AIR WILL BEGIN TO WIN OUT HELPING TO DECREASE THE CLOUD OVERAGE FROM WEST TO EAST ACROSS WEST CENT MN. TEMPERATURES WILL BE VERY DEPENDENT ON BREAKING UP OF CLOUDS. THE WEST AND NORTHWEST SHOULD REACH THE LOWER 60S WITH THE EAST CENT MN COUNTIES IN THE UPPER 50S TO NEAR 60 WITH MORE ABUNDANT CLOUD COVER...AND WEST CENT WI REACHING THE LOW TO MID 50S WITH CONTINUED CLOUDS AND SHOWERS. HIGH PRESSURE BUILDS IN TONIGHT WITH WEAK SFC FLOW TAKING HOLD. ADDED FOG FOR MUCH OF THE EASTERN CWA GIVEN THE RAINFALL AND DECREASING WINDS. INTERESTING WEATHER CONTINUES INTO EARLY NEXT WEEK AS CUTOFF UPPER LOW SPINS EASTWARD ACROSS THE APPALACHIANS AND BROAD CLOSED OFF UPPER LOW CURRENTLY OVER THE WASHINGTON STATE/BRITISH COLUMBIA BORDER TAKES RESIDENCE OVER MUCH OF THE NORTHWEST U.S. AS OMEGA BLOCK SETS UP OVER THE EASTERN PACIFIC. LOCALLY...THIS SETS UP SOUTHERLY UPPER LEVEL FLOW WITH SFC LOW PRESSURE BECOMING ESTABLISHED TO THE WEST OVER THE HIGH PLAINS UNDER UPPER HEIGHT FALLS. THIS WILL ALLOW SOUTHERLY SFC FLOW TO TAKE OVER INTO SUNDAY AND CONTINUE THROUGH MONDAY WITH MID LEVEL WARMTH BUILDING OVERHEAD AS EVIDENCED BY +10 TO +12 H85 TEMPS. THIS WILL ALLOW A NICE WARM UP INTO THE UPPER 60S TO AROUND 70 SUNDAY AND MONDAY. A FRONTAL BOUNDARY WILL APPROACH MONDAY WITH ADDITIONAL WARMING THROUGH COMPRESSIONAL HEATING POSSIBLE SO WILL NEED TO WATCH TEMPS MONDAY. WITH THE UPPER LOW STILL HANGING BACK WELL TO THE WEST MONDAY THE FRONT WILL TAKE ITS TIME CROSSING THE AREA. THE UPPER LOW THEN BEGINS TO KICK NORTHEAST INTO CENTRAL CANADA AS A LOW UNDERCUTS THE PACIFIC OMEGA RIDGE ALLOWING EVOLUTION INTO A REX PATTERN TO TAKE PLACE. THE LOCAL RESULT IS SFC CYCLOGENESIS OVER THE UPPER MISSISSIPPI RIVER VALLEY BY EARLY TUESDAY SENDING STRENGTHENING SFC LOW NORTHWARD ACROSS EASTERN MN TUESDAY MORNING. SHOWERS AND THUNDERSTORMS ARE EXPECT TO DEVELOP AS EARLY AS MONDAY MORNING ACROSS WEST-CENTRAL MINNESOTA AS FRONT APPROACHES WITH BETTER CHANCES ARRIVING MONDAY EVENING AS SFC LOW INTENSIFIES. NAM-WRF IS SHOWING STRONGER INSTABILITY AT THIS POINT WITH CAPE VALUES EXCEEDING 1000 J/KG AND BEST COLUMN LI/S OF -4 WITH STRONGER MOISTURE ADVECTION THAN THE GFS. PWAT INCREASES OF MORE THAN A QUARTER INCH IN 6 HOURS ALSO APPEAR MONDAY EVENING. THE EASTWARD PROGRESS OF THE FRONT SLOWS TUESDAY MORNING AS THE SFC LOW MOVES NORTHWARD ALONG IT ALLOWING A LONGER PERIOD OF SHOWERS AND THUNDERSTORMS ACROSS EAST CENT MN AND WEST CENT WI. SFC HIGH PRESSURE SETTLES TO THE WEST INTO WEDNESDAY BUT SEVERAL SHORTWAVES TRAVERSE THE AREA KEEPING A LOW CHANCE FOR ADDITIONAL SHOWERS BUT DRY CONDITIONS LOOK TO FILL IN DURING THE DAY WEDNESDAY WITH HIGH PRESSURE TO THE SOUTH. COOLER AIR WILL ALSO ARRIVE WITH H85 TEMPS BACK BELOW ZERO. BRIEF ZONAL FLOW OF AIR IN THE MID LEVELS KEEPS THINGS QUIET INTO WEDNESDAY NIGHT BUT THERE ARE INDICATIONS OF UPPER FLOW TRYING TO BUCKLE WITH ANOTHER SFC LOW APPROACHING FROM THE WEST. WARM AIR ADVECTION COMMENCES THURSDAY MORNING WITH ENOUGH MOISTURE IN PLACE BY THAT TIME TO SUPPORT PRECIP CHANCES ONCE AGAIN. ..MDB.. && .AVIATION.../12Z TAF ISSUANCE/ THE TAF ISSUANCE FOR THIS PERIOD REFLECTS A 50H CUTOFF LOW CROSSING THE CENTRAL MISSISSIPPI VALLEY WITH DEFORMATION RELATED PRECIPITATION ACROSS SOUTHERN MN INTO WESTERN WISCONSIN. ACCORDINGLY...KMSP...KEAU AND KRNH START OUT WITH IFR CONDITIONS IN LOW CEILINGS. THE THREAT FOR PRECIPITATION DROPS OFF AT KMSP AROUND 14Z BUT LINGERS THROUGH MORNING AT KEAU. WITH A NARROW RIDGE OF HIGH PRESSURE FORECAST ACROSS MN TNGT...A GOOD PART OF THE AREA APPEARS VULNERABLE FOR SOME FOG. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 245 AM CDT FRI APR 18 2008 .DISCUSSION... SCATTERED AREAS OF -RA CONTINUING TO MOVE ACROSS SC/SE MN INTO WI WELL AHEAD OF VERY SLOW MOVING UPPER LOW WEST OF MKC. PRECIPITATION WILL REMAIN LIGHT AND SCATTERED DURING THE MORNING BUT BOTH THE NAM AND GFS 295K ISENTROPIC SHOW A STRONGER PUSH DEVELOPING AROUND 18Z AND CONTINUING INTO TONIGHT. THUS FORECAST HAS HIGHER POPS FOR THE AFTERNOON THAN THE MORNING HOURS. WILL BE A SUBSTANTIAL RANGE IN MAX TEMPERATURES AGAIN TODAY WITH AREAS AROUND AXN CLIMBING INTO THE LOWER 60S WITH SOME SUN AND THE EAU AND AEL AREAS IN THE LOWER 50S UNDER CLOUDS AND SHOWERS. INCREASED CLOUDS FOR SATURDAY...ESPECIALLY IN THE EASTERN HALF OF AREA AND UPPED POPS A BIT AS FAR WEST AS EC MN WITH ISENTROPIC STILL SHOWING SOME UPGLIDE AND HIGH RH AND 850 MB STILL SHOWING COOL CYCLONIC FLOW. SUNDAY LOOKS TO BE A BETTER DAY AS SLOW MOVING UPPER LOW FINALLY PULLS OFF WELL TO THE EAST. CU RULES DO SHOW POTENTIAL OF BKN CU DEVELOPING THOUGH ON SUNDAY. RESPITE FROM CLOUDS AND PRECIP CHANCES WILL BE BRIEF WITH NEXT SYSTEM MOVING IN FOR MONDAY. TEMPS WILL HAVE TROUBLE WARMING UP IN WAKE OF THIS SYSTEM WITH COOL WNW FLOW THRU MOST OF PERIOD AND SHOWER CHANCES. && .AVIATION.../06Z TAF ISSUANCE/ LOWER CEILINGS GRADUALLY DEVELOPING INTO SC MN INTO WC WISC AS RAIN CONTINUES TO TRACK ACROSS THAT AREA...INCLUDING KEAU. LATEST NAM AND RUC DO SHOW SLOW NWD MOVEMENT INTO KRNH AND THEN KMSP...AND RADAR DOES CONFIRM THAT. THUS HAVE BROUGHT LIGHT RAIN INTO KRNH AFTER DAYBREAK AND KMSP LATE IN THE MORNING. MVFR CEILINGS POSSIBLE BY LATE MORNING AT KEAU AND MID AFTERNOON AT KRNH AND KMSP. LOOKS LIKE KRWF AND KSTC WILL JUST MISS OUT ON PRECIP AND SHOULD JUST SEE OVERCAST MID CLOUDS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1204 AM CDT FRI APR 18 2008 .UPDATE... UPDATED FOR AVIATION DISCUSSION BELOW. && .DISCUSSION... RAIN BEGINNING TO INCREASE IN COVERAGE AT MID AFTERNOON OVER SOUTH CENTRAL MN AND ADJOINING AREAS OF WEST CENTRAL WI. NAM 295K THETA SURFACE SHOWING STRONG UPGLIDE DEVELOPING IN THIS AREA. THIS IS ALONG A MID LEVEL DEFORMATION ZONE THAT STRETCHES FROM THE CENTRAL PLAINS TO THE WESTERN GREAT LAKES. IN ADDITION...FRONTOGENESIS IN THE 600-700 MB LAYER IS SHOWN IN THIS SAME AREA. SOME LIGHTNING STRIKES AS WELL NEAR KRST AND KSLB AT MID AFTERNOON. RUC BEST LI CAPTURES THE INSTABILITY WELL AND SHOWS SOUTH CENTRAL MN INTO THE KEAU AREA VULNERABLE FOR THUNDER THIS EVENING. THE NAM SHOWS A DECREASE IN THE FORCING AND INSTABILITY AFTER MIDNIGHT WHICH LASTS THROUGH A PORTION OF FRIDAY MORNING. HENCE...A DECREASE IN POPS SHOWN. THEN THE UPGLIDE RETURNS FRIDAY AFTERNOON AND EVENING...FOR ABOUT THE SAME AREA WITH LIKELY TO CATEGORICAL POPS FOR A TIME. ALL OF THIS IS ASSOCIATED WITH LOW PRESSURE ALOFT ENTERING THE CENTRAL PLAINS FROM CO/NM THIS AFTERNOON. THE UPPER LEVEL LOW TAKES ON NEGATIVE TILT TO OUR SOUTH AND SOUTHEAST FRIDAY INTO SATURDAY...KEEPING WEST CENTRAL WI IN THE RAIN CHANCES THROUGH PART OF SATURDAY. THE WHOLE PATTERN IS BACKED UP DUE TO ANOTHER UPPER LOW IN THE WEST ATLANTIC AND A BLOCK OVER THE NORTHERN ATLANTIC TO THE EAST OF GREENLAND. SLOW MOVEMENT ARE THE KEY WORDS FOR THIS WEATHER SYSTEM. SUNDAY SHOULD BE THE BEST DAY WEATHERWISE IF THINGS CREEP ALONG AS FORECAST. THE LOW LEVEL FLOW WILL BE INCREASING FROM THE SOUTHEAST AS A MAMMOTH UPPER LOW MOVES INTO THE NORTHERN ROCKIES BY MONDAY. SURFACE LOW PRESSURE WILL BE FORMING OVER THE CENTRAL AND NORTHERN PLAINS. AN ASSOCIATED COLD FRONT TRAILING FROM THE LOW IS PROGGED INTO WESTERN MN MONDAY MORNING AND INTO THE EASTERN CWA BY EVENING. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED WITH THE FROPA. THE TUESDAY THROUGH THURSDAY PERIOD IS UNSETTLED. BASICALLY...THE UPPER LOW SHOULD DRIFT NORTHEAST TO SOUTH CENTRAL CANADA WHILE SHORT WAVES RIPPLE ACROSS THE NORTHERN PLAINS WITH BOUTS OF PRECIPITATION. FOR NOW...HAVE SHOWER CHANCES ON TUESDAY AND THURSDAY. TEMPERATURES NEAR SEASONAL LEVELS THROUGH THE PERIOD. THE RAIN/CLOUDS TOMORROW AND SATURDAY OVER EASTERN AND SOUTHERN AREAS WILL HOLD THINGS BACK A LITTLE. && .AVIATION.../06Z TAF ISSUANCE/ LOWER CEILINGS GRADUALLY DEVELOPING INTO SC MN INTO WC WISC AS RAIN CONTINUES TO TRACK ACROSS THAT AREA...INCLUDING KEAU. LATEST NAM AND RUC DO SHOW SLOW NWD MOVEMENT INTO KRNH AND THEN KMSP...AND RADAR DOES CONFIRM THAT. THUS HAVE BROUGHT LIGHT RAIN INTO KRNH AFTER DAYBREAK AND KMSP LATE IN THE MORNING. MVFR CEILINGS POSSIBLE BY LATE MORNING AT KEAU AND MID AFTERNOON AT KRNH AND KMSP. LOOKS LIKE KRWF AND KSTC WILL JUST MISS OUT ON PRECIP AND SHOULD JUST SEE OVERCAST MID CLOUDS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1100 PM CDT SAT APR 19 2008 ...UPDATED FOR AVIATION... .UPDATE... STRATUS DECK HAS BEEN SLOW TO MOVE EAST TONIGHT...WITH H8 RIDGE AXIS A GOOD DELINEATOR TO THE WESTERN EDGE OF STRATUS. QUICK PEEK AT LATEST RUC INDICATES H8 RIDGE AXIS WILL EDGE SLOWLY EAST OVERNIGHT AND WILL CLEAR EASTERN EDGE OF CWA BY 12 UTC. GIVEN THIS SCENARIO...INCREASED MINIMUM TEMPETURES A COUPLE DEGREES ACROSS EASTERN CWA DUE TO PERSISTENT CLOUD COVER. ALSO TRIMMED FOG POTENTIAL A LITTLE WHERE SKIES HAVE CLEARED. CIRRUS SHIELD IS ADVECTING RAPIDLY EASTWARD ACROSS KANSAS AND COUPLED WITH SLIGHTLY GREATER LOW LEVEL WINDS WILL DETRACT FROM RADIATIONAL FOG FORMATION. GIVEN TEMPERATURES WILL DROP WITH 2-3 DEGREES OF DEWPOINTS...KEPT MENTION OF PATCHY FOG IN FORECAST...ESPECIALLY ALONG RIVER VALLEYS OF NORTH WEST AND NORTH CENTRAL MISSOURI. .DISCUSSION... UPR LOW HAS FINALLY EXITED STAGE RIGHT THIS AFTN...TAKING WITH IT A RATHER PESKY LOW-LVL CLOUD DECK. THIS CLEARING HAS ALLOWED MANY LOCATIONS TO EXPERIENCE SUNSHINE TODAY...HOWEVER CLEARING MAY BE TOO LATE FOR THOSE LIVING ACROSS THE EASTERN HALF OF THE CWA. OTHERWISE FAIRLY BENIGN WEATHER CAN BE EXPECTED FOR THE NEXT 36-48 HOURS...AS MID-LVL RIDGING MOVES IN FROM THE WEST. FOR TONIGHT...GIVEN THE EXTENSIVE CLOUD COVER OVER THE NE HALF OF THE CWA DEW POINTS HAVE NOT BEEN ABLE TO SCOUR OUT AS IN LOCATIONS FURTHER WEST. THUS WITH SFC RIDGE AXIS SLIDING OVERHEAD OVERNIGHT AND CLEARING SKIES FROM WEST TO EAST...FEEL AREAS OF FOG WILL BE POSSIBLE BY DAYBREAK. PERHAPS THE NICEST DAY OF THE YEAR SO FAR WILL BE ON TAP FOR SUNDAY AS H850 RIDGE AXIS SLIDES EAST AND SFC WINDS QUICKLY VEER TO THE SW. EVEN THOUGH WE MAY NOT BE ABLE TO TAP THE FULL POTENTIAL OF THE +13C TO +15C H850 AIR OVERHEAD...HIGHS WILL BE SOME 10+ DEGREES ABOVE NORMAL OVERALL. GUIDANCE DOES INDICATE A BIT OF MID-UPR LVL CLOUD COVER LIFTING NE BY MID-DAY...AT THIS POINT NOT FEELING THIS WILL HURT TEMPS MUCH. MODELS CONTINUE TO BOUNCE AROUND A BIT ON UPCOMING COOL FRONT ON MON. PREFER THE SLIGHTLY SLOWER GFS/UKMET/CMC SOLN...KEEPING EFFECTIVE FRONT WEST OF THE CWA BY MON AFTN...AND MUCH OF THE AREA CAPPED. THEREFORE HAVE TRIMMED BACK MON AM POPS. BEST SYNOPTIC FORCING DOESN`T ARRIVE UNTIL MON EVE/OVERNIGHT AS DISTURBANCE SWINGS AROUND UPR TROUGH AND SHOULD ERODE EML. QUESTION MARK FOR MONDAY WILL BE SPEED AND VOLUME OF MOISTURE WHICH CAN BE LIFTED NORTHWARD. DECENT MOISTURE TRANSPORT SUNDAY NIGHT WILL QUICKLY BE SHUNTED EAST AS LLJ VEERS RATHER RAPIDLY. DEEPENING ON VOLUME OF MOISTURE SURGE AND ASSOCIATED STRATUS DECK...INSTABILITY/HEATING MAY BE AFFECTED OVER THE CWA. AS FAR AS SVR CHANCES ARE CONCERNED...SHEAR AND INSTABILITY REMAIN THE BIGGEST QUESTIONS...CANNOT RULE OUT SCT STRONG CONVECTION OVERNIGHT MONDAY ESPECIALLY OVER THE NORTHERN CWA. HOWEVER...MADE FEW CHANCES TO CURRENT POPS AND TEMPS AS BOTH SEEM REASONABLE ATTM. DUX MEDIUM RANGE (TUE-SAT) WHILE MODELS SHOW SOME DIFFERENCES IN TIMING THE FRONT THROUGH THE REGION ON TUESDAY...THEY ARE IN AGREEMENT WITH IT GETTING EAST OF THE FORECAST AREA BY TUESDAY EVENING. SO HAVE TAPERED POPS DURING THE DAY TUESDAY WITH FORECAST AREA DRY BY TUESDAY NIGHT. EXPECT HIGH TEMPERATURES TUESDAY TO BE WELL INTO THE 70S AHEAD OF THE FRONT...WITH READINGS REACHING THE MID 60S BEHIND IT. RELATIVELY COOL HIGH PRESSURE MOVING IN BEHIND THE FRONT SHOULD KEEP THE REGION DRY THROUGH WEDNESDAY...WITH TEMPS CLOSER TO NORMAL...MAINLY IN THE MID 60S TO AROUND 70 DEGREES. HOWEVER THE FORECAST FOR THE END OF THE WEEK CONTINUES TO BE SOMEWHAT PROBLEMATIC. MODELS ARE NOT IN GOOD AGREEMENT ON THE EVOLUTION OF THE NEXT SYSTEM. OPERATIONAL GFS IS THE OUTLIER...DEVELOPING A STRONG SURFACE LOW AND ASSOCIATED COLD FRONT OVER THE CENTRAL PLAINS...THEN TAKING THE COLD FRONT QUICKLY EAST THROUGH THE REGION BY THURSDAY NIGHT. THE UPPER LOW IS QUICK ON ITS HEELS...MOVING ACROSS THE REGION ON FRIDAY. HAVE TRENDED MORE TOWARD THE ECMWF SOLUTION...WHICH IS A LITTLE SLOWER AND A LITTLE FARTHER NORTH WITH THE SURFACE AND UPPER LOWS. HAVE TRIMMED BACK POPS A LITTLE WEDNESDAY NIGHT...THINKING DRY EASTERLY WINDS WILL HOLD OFF PRECIP IN EASTERN SECTIONS. IF MOISTURE RETURN IS SHARP ENOUGH AND FAR ENOUGH EAST...THEN MAY GET STORMS ON THE LEADING EDGE ACROSS EASTERN KANSAS AND WESTERN MISSOURI. HOWEVER BASED ON THE LOCATION OF THE EXPECTED DEVELOPING LOW...THINK BEST CHANCE WILL BE WEST OF THE FORECAST AREA WEDNESDAY NIGHT. MOISTURE CONTINUES TO OVERSPREAD THE REGION ON THURSDAY...POSSIBLY BRINGING SCATTERED THUNDERSTORMS. HAVE PRECIP CHANCES CONTINUING THROUGH FRIDAY...WHEN THE ECMWF BRINGS THE COLD FRONT ACROSS THE FORECAST AREA. PROGS SUGGEST THE FRONT MAY HANG UP ACROSS OR JUST SOUTH OF THE FORECAST AREA. POPS AND QPF ARE CURRENTLY NOT VERY HIGH DUE TO THE EXPECTED TIMING CHANGES IN UPCOMING FORECASTS...BUT BOTH WILL INCREASE AS THE FORECAST BECOMES MORE CLEAR. NRR && .AVIATION... FOR THE 06Z TAFS...NAM AND RUC SOUNDINGS DEPICTING THE POTENTIAL FOR DEVELOPMENT BEGINNING IN THE 08-09 UTC TIMEFRAME AT STJ AND PERSISTING THROUGH 13 UTC. BASED ON CLIMATOLOGY...THE DENSEST FOG LIKELY WILL NOT OCCUR UNTIL AROUND SUNRISE...THUS CONTINUED PREVIOUS TAF FORECAST TREND OF INTRODUCING TEMPO GROUP IN THE 10-13 TIMEFRAME. ANY FOG THAT DEVELOPS AT STJ WILL DISSIPATE BY 14-15 UTC DUE TO MIXING. BY LATE MORNING...PRESSURE GRADIENT TIGHTENS SUFFICIENTLY THUS WIND SPEEDS AT ALL THREE TAF SITES WILL INCREASE AT OR ABOVE 12 KNOTS BY 16 UTC. OTHERWISE...VFR CONDITIONS WILL PREVAIL. 24 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1035 PM CDT SAT APR 19 2008 .UPDATE... STRATUS DECK HAS BEEN SLOW TO MOVE EAST TONIGHT...WITH H8 RIDGE AXIS A GOOD DELINEATOR TO THE WESTERN EDGE OF STRATUS. QUICK PEEK AT LATEST RUC INDICATES H8 RIDGE AXIS WILL EDGE SLOWLY EAST OVERNIGHT AND WILL CLEAR EASTERN EDGE OF CWA BY 12 UTC. GIVEN THIS SCENARIO...INCREASED MINIMUM TEMPETURES A COUPLE DEGREES ACROSS EASTERN CWA DUE TO PERSISTENT CLOUD COVER. ALSO TRIMMED FOG POTENTIAL A LITTLE WHERE SKIES HAVE CLEARED. CIRRUS SHIELD IS ADVECTING RAPIDLY EASTWARD ACROSS KANSAS AND COUPLED WITH SLIGHTLY GREATER LOW LEVEL WINDS WILL DETRACT FROM RADIATIONAL FOG FORMATION. GIVEN TEMPERATURES WILL DROP WITH 2-3 DEGREES OF DEWPOINTS...KEPT MENTION OF PATCHY FOG IN FORECAST...ESPECIALLY ALONG RIVER VALLEYS OF NORTH WEST AND NORTH CENTRAL MISSOURI. .DISCUSSION... UPR LOW HAS FINALLY EXITED STAGE RIGHT THIS AFTN...TAKING WITH IT A RATHER PESKY LOW-LVL CLOUD DECK. THIS CLEARING HAS ALLOWED MANY LOCATIONS TO EXPERIENCE SUNSHINE TODAY...HOWEVER CLEARING MAY BE TOO LATE FOR THOSE LIVING ACROSS THE EASTERN HALF OF THE CWA. OTHERWISE FAIRLY BENIGN WEATHER CAN BE EXPECTED FOR THE NEXT 36-48 HOURS...AS MID-LVL RIDGING MOVES IN FROM THE WEST. FOR TONIGHT...GIVEN THE EXTENSIVE CLOUD COVER OVER THE NE HALF OF THE CWA DEW POINTS HAVE NOT BEEN ABLE TO SCOUR OUT AS IN LOCATIONS FURTHER WEST. THUS WITH SFC RIDGE AXIS SLIDING OVERHEAD OVERNIGHT AND CLEARING SKIES FROM WEST TO EAST...FEEL AREAS OF FOG WILL BE POSSIBLE BY DAYBREAK. PERHAPS THE NICEST DAY OF THE YEAR SO FAR WILL BE ON TAP FOR SUNDAY AS H850 RIDGE AXIS SLIDES EAST AND SFC WINDS QUICKLY VEER TO THE SW. EVEN THOUGH WE MAY NOT BE ABLE TO TAP THE FULL POTENTIAL OF THE +13C TO +15C H850 AIR OVERHEAD...HIGHS WILL BE SOME 10+ DEGREES ABOVE NORMAL OVERALL. GUIDANCE DOES INDICATE A BIT OF MID-UPR LVL CLOUD COVER LIFTING NE BY MID-DAY...AT THIS POINT NOT FEELING THIS WILL HURT TEMPS MUCH. MODELS CONTINUE TO BOUNCE AROUND A BIT ON UPCOMING COOL FRONT ON MON. PREFER THE SLIGHTLY SLOWER GFS/UKMET/CMC SOLN...KEEPING EFFECTIVE FRONT WEST OF THE CWA BY MON AFTN...AND MUCH OF THE AREA CAPPED. THEREFORE HAVE TRIMMED BACK MON AM POPS. BEST SYNOPTIC FORCING DOESN`T ARRIVE UNTIL MON EVE/OVERNIGHT AS DISTURBANCE SWINGS AROUND UPR TROUGH AND SHOULD ERODE EML. QUESTION MARK FOR MONDAY WILL BE SPEED AND VOLUME OF MOISTURE WHICH CAN BE LIFTED NORTHWARD. DECENT MOISTURE TRANSPORT SUNDAY NIGHT WILL QUICKLY BE SHUNTED EAST AS LLJ VEERS RATHER RAPIDLY. DEEPENING ON VOLUME OF MOISTURE SURGE AND ASSOCIATED STRATUS DECK...INSTABILITY/HEATING MAY BE AFFECTED OVER THE CWA. AS FAR AS SVR CHANCES ARE CONCERNED...SHEAR AND INSTABILITY REMAIN THE BIGGEST QUESTIONS...CANNOT RULE OUT SCT STRONG CONVECTION OVERNIGHT MONDAY ESPECIALLY OVER THE NORTHERN CWA. HOWEVER...MADE FEW CHANCES TO CURRENT POPS AND TEMPS AS BOTH SEEM REASONABLE ATTM. DUX MEDIUM RANGE (TUE-SAT) WHILE MODELS SHOW SOME DIFFERENCES IN TIMING THE FRONT THROUGH THE REGION ON TUESDAY...THEY ARE IN AGREEMENT WITH IT GETTING EAST OF THE FORECAST AREA BY TUESDAY EVENING. SO HAVE TAPERED POPS DURING THE DAY TUESDAY WITH FORECAST AREA DRY BY TUESDAY NIGHT. EXPECT HIGH TEMPERATURES TUESDAY TO BE WELL INTO THE 70S AHEAD OF THE FRONT...WITH READINGS REACHING THE MID 60S BEHIND IT. RELATIVELY COOL HIGH PRESSURE MOVING IN BEHIND THE FRONT SHOULD KEEP THE REGION DRY THROUGH WEDNESDAY...WITH TEMPS CLOSER TO NORMAL...MAINLY IN THE MID 60S TO AROUND 70 DEGREES. HOWEVER THE FORECAST FOR THE END OF THE WEEK CONTINUES TO BE SOMEWHAT PROBLEMATIC. MODELS ARE NOT IN GOOD AGREEMENT ON THE EVOLUTION OF THE NEXT SYSTEM. OPERATIONAL GFS IS THE OUTLIER...DEVELOPING A STRONG SURFACE LOW AND ASSOCIATED COLD FRONT OVER THE CENTRAL PLAINS...THEN TAKING THE COLD FRONT QUICKLY EAST THROUGH THE REGION BY THURSDAY NIGHT. THE UPPER LOW IS QUICK ON ITS HEELS...MOVING ACROSS THE REGION ON FRIDAY. HAVE TRENDED MORE TOWARD THE ECMWF SOLUTION...WHICH IS A LITTLE SLOWER AND A LITTLE FARTHER NORTH WITH THE SURFACE AND UPPER LOWS. HAVE TRIMMED BACK POPS A LITTLE WEDNESDAY NIGHT...THINKING DRY EASTERLY WINDS WILL HOLD OFF PRECIP IN EASTERN SECTIONS. IF MOISTURE RETURN IS SHARP ENOUGH AND FAR ENOUGH EAST...THEN MAY GET STORMS ON THE LEADING EDGE ACROSS EASTERN KANSAS AND WESTERN MISSOURI. HOWEVER BASED ON THE LOCATION OF THE EXPECTED DEVELOPING LOW...THINK BEST CHANCE WILL BE WEST OF THE FORECAST AREA WEDNESDAY NIGHT. MOISTURE CONTINUES TO OVERSPREAD THE REGION ON THURSDAY...POSSIBLY BRINGING SCATTERED THUNDERSTORMS. HAVE PRECIP CHANCES CONTINUING THROUGH FRIDAY...WHEN THE ECMWF BRINGS THE COLD FRONT ACROSS THE FORECAST AREA. PROGS SUGGEST THE FRONT MAY HANG UP ACROSS OR JUST SOUTH OF THE FORECAST AREA. POPS AND QPF ARE CURRENTLY NOT VERY HIGH DUE TO THE EXPECTED TIMING CHANGES IN UPCOMING FORECASTS...BUT BOTH WILL INCREASE AS THE FORECAST BECOMES MORE CLEAR. NRR && .AVIATION... FOR THE 18Z TAFS...MVFR DECK NOW RAPIDLY DISSIPATING ACROSS THE TERMINAL LOCATIONS EARLY THIS AFTN. CLOUD DECK WILL CONTINUE TO LIFT INTO VFR CATEGORY WITHIN THE NEXT HOUR. SFC RIDGE WILL SLIDE ACROSS THE TERMINAL SITES THIS EVENING...WITH VARIABLE WINDS EXPECTED. WINDS SHOULD QUICKLY PICK UP SUN MORNING AS LOW-LVL FLOW VEERS TO THE SW. SOUNDINGS INDICATE THE POTENTIAL FOR A BIT OF LIGHT BRIEF FOG DEVELOPMENT IN STJ...AS A RESULT HAVE INTRODUCED A TEMPO GROUP FROM 10-13Z DUX && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 943 PM CDT SAT APR 19 2008 .DISCUSSION... HAVE UPDATED FOR A COUPLE OF CHANGES THIS EVENING. SFC RIDGE AXIS AT 02Z WAS ALREADY LOCATED IN CTLR IA...WITH SELY WINDS BECOME ESTABLISHED ACROSS THE CWA. THINK THE WINDS WILL BE ENOUGH TO KEEP MENTIONABLE FOG FROM FORMING...ESPECIALLY IF DRIER DEWPOINTS CONTINUE TO PUSH SEWD OUT OF SD/CTRL NEB. AS A RESULT...HAVE PULLED FOG MENTION FOR THE LATE OVERNIGHT/EARLY MORNING HOURS. HAVE ALSO UPDATED SKY GRIDS FOR CURRENT TRENDS...AS CWA HAS BEEN CLEAR FOR SEVERAL HRS. WILL SEE CI WORK SLOWLY NWD OUT OF KS INTO THE SWRN CWA THROUGH THE OVERNIGHT HOURS...WITH ERN CWA LIKELY TO STAY CLEAR THROUGH THE NIGHT. KEPT GOING MIN TEMPS WITH BALANCE BETWEEN DRIER AIR/CLEAR SKIES AND INCREASING WINDS PREVENTING A FULL DROP-OFF OF TEMPS. && .PREV DISCUSSION... /ISSUED 215 PM CDT SAT APR 19 2008/ DISCUSSION... SHORT TERM CONCERNS WILL BE TEMPS AND FOG POTENTIAL...WINDS SUNDAY...THEN FRONTAL PASSAGE MONDAY/ PRECIP POTENTIAL WITH THE FRONT AND BEHIND THE FRONT MONDAY THROUGH TUESDAY MORNING. STORM SYSTEM HEADING INTO THE OHIO RIVER VALLEY FINALLY PULLING THE CLD SHIELD EAST OF THE FCST AREA. SFC HIGH PRES OVER THE MO VALLEY WILL YIELD LIGHT WINDS AND CLEAR SKIES TONIGHT. FOG...CONTINUED TO MENTION FOG ALONG THE MO RIVER AND EAST INTO WRN IA WITH 1-3 DEG SFC DEWPOINT DEPRESSIONS. HOW FAR TO BRING FOG WEST IS THE QUESTION WITH LOW LEVEL WINDS BEGINNING TO STRENGTHEN BY MORNING. NEXT TO THE AREAS OF FOG ALONG THE MO RIVER...INCLUDED A STRIPE OF PATCHY FOG TO NR THE THE H85 RIDGE LINE...WITH LNK BEING ON THE WRN EXTENT OF THE FOG. LOWS IN THE 40S STILL LOOK REASONABLE TONIGHT. WINDS...THE NAM AND TO A LESSER EXTENT...THE GFS HAS THE 40-50KT LOW LEVEL JET OVER CNTRL NEBRASKA SHIFTING INTO EASTERN NEBRASKA DURING THE MORNING AND WRN IA DURING THE AFTERNOON. THE OVERNIGHT SHIFT WILL NEED TO CONSIDER WIND ADVISORY. PER BUFKIT FCST SOUNDINGS NAM FCSTS WIND ADVISORY POTENTIAL AT OFK/FBY AROUND NOON...AT LNK EARLY IN THE AFTERNOOON...AND AT OMA MID AFTERNOON AND INTO SW IA BY EVE. CURRENT FCST IS CLOSE OR AT WIND ADVISORY FOR SUNDAY...DECREASING AFTER EARLY EVENING...BUT STILL WINDY/BREEZY OVERNIGHT. PRECIP POTENTIAL MONDAY THROUGH EARLY TUESDAY...THE SFC FNT WILL BE MOVING THROUGH THE FCST AREA MONDAY. WITH DYNAMICS NOT REAL IMPRESSIVE...HAVE A SLIGHT CHANCE FOR -TSRA LATE SUNDAY NIGHT...THEN A SLIGHT CHC DURING THE MORNING. WITH A SHORTWAVE TROF APPROACHING IN THE FLOW POST-FRONTAL MONDAY AFTERNOON...KEPT A SLIGHT CHC/CHC FOR SHOWERS/-TSRA. CURRENTLY HAVE HIGHEST POPS MONDAY NIGHT. WITH LINGERING ELEVATED INSTABILITY...LEFT THUNDER MENTION IN. SHORTWAVE IS MOVING EAST OF THE AREA TUESDAY...THUS LOWERED POPS IN THE MORNING AND DROPPED THEM IN THE AFTERNOON. HIGHS IN THE UPR 70S SUNDAY...THEN 60S/70S MONDAY AND TUESDAY. THE EXTENDED TUESDAY NIGHT STARTS OUT WITH THE SFC FRONT S OF THE FCST AREA AND HIGH PRES BUILDING IN. THE NEXT MID TROPOSPHERIC TROF IS OVR THE NW U.S. AND THE ECMWF/GFS SHOW A WEAK WAVE LIFTING ACRS THE WRN PLAINS...MEANWHILE A SFC WRMFT IS DEVELOPING OUT WEST. AM COUNTING OF THIS FEATURE TO BE FAR ENOUGH WEST...TO NOT INCLUDE PRECIP WED. WEDNESDAY NIGHT...HOWEVER...THE SFC LOW FM CO TO WY MOVES INTO WRN NEB AND WRN KS AND THE LOW LEVEL JET INCREASES AND VEERS WITH PRECIP EXPANDING INTO THE PLAINS. AS WE GET INTO THU...THERE ARE A VARIETY OF SOLUTIONS AND TIMING. THE CANADIAN LIFTS THE SFC LOW NORTH TOWARD THE SD/ND BORDER...THE ECMWF TAKES IT TO ERN SD...AND THE GFS TAKES IT TO NW IA. HPC IS USING A ECWMF/ENSEMBLE MEAN APPROACH TO THE EXTENDED. LOOKS LIKE A CHC FOR TSRA THU AND THU NIGHT. HELD ON TO SOME POPS FRIDAY DEPENDING ON THE SPEED/AMPLITUDE OF THE SYSTEM. HIGHS IN THE 60S AND 70S IN THE EXTENDED...EXCEPT SOME 50S FOR FRIDAY. AVIATION... TAF SITES KOMA...KLNK AND KOFK...THRU 20/18Z. MAIN FORECAST ISSUES TONIGHT REVOLVE AROUND POTENTIAL FOG DEVELOPMENT ACROSS EXTREME EASTERN NEBRASKA AND WESTERN IOWA. SURFACE DEWPOINT DEPRESSIONS ARE PROGGED TO FALL TO 1 TO 2 DEGREES WITH LIGHT SOUTHEAST WINDS. RUC WAS MOST AGGRESSIVE WITH FOG DEVELOPMENT...WHICH WAS GENERALLY USED FOR THE FORECAST. ADDED SOME FOG AT KLNK/KOMA BY 09Z/10Z...WITH POTENTIAL TO GET DOWN TO 1/2SM AT KOMA AND 1SM AT KLNK FROM 11Z-13Z...BUT THEN QUICKLY BACK TO P6SM BY 14Z. INCREASING SOUTHEASTERLY SURFACE WINDS SUNDAY MORNING WERE ALSO CONSIDERED...WITH SPEEDS APPROACHING 20KTS SUSTAINED BY 16Z...AND LIKELY HIGHER BY 18Z AND BEYOND ESPECIALLY AT KOFK. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ MAYES ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 215 PM CDT SAT APR 19 2008 .DISCUSSION... SHORT TERM CONCERNS WILL BE TEMPS AND FOG POTENTIAL...WINDS SUNDAY...THEN FRONTAL PASSAGE MONDAY/ PRECIP POTENTIAL WITH THE FRONT AND BEHIND THE FRONT MONDAY THROUGH TUESDAY MORNING. STORM SYSTEM HEADING INTO THE OHIO RIVER VALLEY FINALLY PULLING THE CLD SHIELD EAST OF THE FCST AREA. SFC HIGH PRES OVER THE MO VALLEY WILL YIELD LIGHT WINDS AND CLEAR SKIES TONIGHT. FOG...CONTINUED TO MENTION FOG ALONG THE MO RIVER AND EAST INTO WRN IA WITH 1-3 DEG SFC DEWPOINT DEPRESSIONS. HOW FAR TO BRING FOG WEST IS THE QUESTION WITH LOW LEVEL WINDS BEGINNING TO STRENGTHEN BY MORNING. NEXT TO THE AREAS OF FOG ALONG THE MO RIVER...INCLUDED A STRIPE OF PATCHY FOG TO NR THE THE H85 RIDGE LINE...WITH LNK BEING ON THE WRN EXTENT OF THE FOG. LOWS IN THE 40S STILL LOOK REASONABLE TONIGHT. WINDS...THE NAM AND TO A LESSER EXTENT...THE GFS HAS THE 40-50KT LOW LEVEL JET OVER CNTRL NEBRASKA SHIFTING INTO EASTERN NEBRASKA DURING THE MORNING AND WRN IA DURING THE AFTERNOON. THE OVERNIGHT SHIFT WILL NEED TO CONSIDER WIND ADVISORY. PER BUFKIT FCST SOUNDINGS NAM FCSTS WIND ADVISORY POTENTIAL AT OFK/FBY AROUND NOON...AT LNK EARLY IN THE AFTERNOOON...AND AT OMA MID AFTERNOON AND INTO SW IA BY EVE. CURRENT FCST IS CLOSE OR AT WIND ADVISORY FOR SUNDAY...DECREASING AFTER EARLY EVENING...BUT STILL WINDY/BREEZY OVERNIGHT. PRECIP POTENTIAL MONDAY THROUGH EARLY TUESDAY...THE SFC FNT WILL BE MOVING THROUGH THE FCST AREA MONDAY. WITH DYNAMICS NOT REAL IMPRESSIVE...HAVE A SLIGHT CHANCE FOR -TSRA LATE SUNDAY NIGHT...THEN A SLIGHT CHC DURING THE MORNING. WITH A SHORTWAVE TROF APPROACHING IN THE FLOW POST-FRONTAL MONDAY AFTERNOON...KEPT A SLIGHT CHC/CHC FOR SHOWERS/-TSRA. CURRENTLY HAVE HIGHEST POPS MONDAY NIGHT. WITH LINGERING ELEVATED INSTABILITY...LEFT THUNDER MENTION IN. SHORTWAVE IS MOVING EAST OF THE AREA TUESDAY...THUS LOWERED POPS IN THE MORNING AND DROPPED THEM IN THE AFTERNOON. HIGHS IN THE UPR 70S SUNDAY...THEN 60S/70S MONDAY AND TUESDAY. THE EXTENDED TUESDAY NIGHT STARTS OUT WITH THE SFC FRONT S OF THE FCST AREA AND HIGH PRES BUILDING IN. THE NEXT MID TROPOSPHERIC TROF IS OVR THE NW U.S. AND THE ECMWF/GFS SHOW A WEAK WAVE LIFTING ACRS THE WRN PLAINS...MEANWHILE A SFC WRMFT IS DEVELOPING OUT WEST. AM COUNTING OF THIS FEATURE TO BE FAR ENOUGH WEST...TO NOT INCLUDE PRECIP WED. WEDNESDAY NIGHT...HOWEVER...THE SFC LOW FM CO TO WY MOVES INTO WRN NEB AND WRN KS AND THE LOW LEVEL JET INCREASES AND VEERS WITH PRECIP EXPANDING INTO THE PLAINS. AS WE GET INTO THU...THERE ARE A VARIETY OF SOLUTIONS AND TIMING. THE CANADIAN LIFTS THE SFC LOW NORTH TOWARD THE SD/ND BORDER...THE ECMWF TAKES IT TO ERN SD...AND THE GFS TAKES IT TO NW IA. HPC IS USING A ECWMF/ENSEMBLE MEAN APPROACH TO THE EXTENDED. LOOKS LIKE A CHC FOR TSRA THU AND THU NIGHT. HELD ON TO SOME POPS FRIDAY DEPENDING ON THE SPEED/AMPLITUDE OF THE SYSTEM. HIGHS IN THE 60S AND 70S IN THE EXTENDED...EXCEPT SOME 50S FOR FRIDAY. && .AVIATION... TAF SITES KOMA...KLNK AND KOFK...THRU 20/18Z. MAIN FORECAST ISSUES TONIGHT REVOLVE AROUND POTENTIAL FOG DEVELOPMENT ACROSS EXTREME EASTERN NEBRASKA AND WESTERN IOWA. SURFACE DEWPOINT DEPRESSIONS ARE PROGGED TO FALL TO 1 TO 2 DEGREES WITH LIGHT SOUTHEAST WINDS. RUC WAS MOST AGGRESSIVE WITH FOG DEVELOPMENT...WHICH WAS GENERALLY USED FOR THE FORECAST. ADDED SOME FOG AT KLNK/KOMA BY 09Z/10Z...WITH POTENTIAL TO GET DOWN TO 1/2SM AT KOMA AND 1SM AT KLNK FROM 11Z-13Z...BUT THEN QUICKLY BACK TO P6SM BY 14Z. INCREASING SOUTHEASTERLY SURFACE WINDS SUNDAY MORNING WERE ALSO CONSIDERED...WITH SPEEDS APPROACHING 20KTS SUSTAINED BY 16Z...AND LIKELY HIGHER BY 18Z AND BEYOND ESPECIALLY AT KOFK. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ ZAPOTOCNY/DEWALD ne AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 826 PM CDT SAT APR 19 2008 .UPDATE... THE MAIN ISSUE OVERNIGHT IS WILL LOWER CLOUDS ADVANCE FROM CNTRL AND NE MN INTO NW MN AND SE ND. SATELLITE LAST FEW HOURS HAS SHOWN THE WRN EDGE OF CLOUDS NR AN KAXN-KADC-KINL LINE WITH THICKEST CLOUDS EAST OF THIS LINE WITH CEILINGS IN THE 4500-5500 FT RANGE EVENTUALLY DROPPING TO IFR RANGE OVER FAR ERN MN INTO WI WHERE MOISTURE IS DEEPER ON NORTH SIDE OF VERY SLOW MOVING UPR LOW IN THE SRN GREAT LAKES/OHIO VALLEY. SFC HIGH PRESSURE RIDGE HAS REMAINED INTACT AGAIN TODAY NR AN INL-AXN LINE KEEPING WITH A SHARP CUTOFF AT 925-800 MB LAYER FROM MOISTURE TO THE EAST AND VERY DRY AIR TO THE WEST. 18Z NAM/RUC AND GFS ALL SHOW IDEA THAT THE 850 MB MOISTURE CURRENT AXN-INL EASTWARD WILL START TO MOVE BACK WEST AS 850 MB WINDS TURN MORE SOUTHEAST AND INCREASE OVERNIGHT AS SFC RIDGE WEAKENS AND MOVES EAST AS MONTANA SFC LOW MOVES NORTHEAST INTO CANADA. 21Z RUC SHOW 850 MB MOISTURE NR AXN AREA MOVING NORTHWEST AFTER 06Z INTO WCNTRL MN AND SE ND AT THIS MAY BE CORRECT. SEEING TRENDS THIS EVENING THAT POINT TO THIS IN THAT 40+ DEW PTS HAVE MOVED INTO WHEATON AND WAHPETON PAST FEW HOURS WITH DEW PTS INCREASING INTO THE UPR 30S INTO SE ND AND NE SD. THUS COORD WITH MPX/DLH AND ADDED MORE CLOUD COVER OVERNIGHT TO SOUTHEAST HALF OF THE FCST AREA. DID NOT GO AS WILD AS RUC WOULD SUGGEST UNTIL CLOUD TRENDS ARE MORE SET. DID ALSO INCREASE DEW PTS A BIT IN WCNTRL MN. && .AVIATION...DID BRING IN SOME MVFR CIGS INTO BEMIDJI OVERNIGHT AS 850 MB FLOW TURNS SOUTHEAST 06Z AND AFTER AND KEPT IN SOME MVFR CIGS TIL LATE MORNING SUNDAY. OTHERWISE FOR NOW KEPT IDEA OF JUST SOME INCREASING CIRRUS AT FARGO-GRAND FORKS. SOUTHEAST WINDS BY 15Z SUNDAY INCREASING TO 15-20 KTS IN THE VALLEY WITH 20-30 KTS BY 20Z. && .PREV DISCUSSION... /ISSUED 300 PM CDT SAT APR 19 2008/ SHORT TERM... /TONIGHT THROUGH TUE/ CURRENT H500 PATTERN SHOWING A LOW OVER THE PAC NW AND SECOND LOW OVER THE CENTRAL MISSISSIPPI VALLEY...WITH RIDGING OVER THE CENTRAL AND NORTHERN PLAINS. AT H850...SEEING 40 DM HEIGHT FALLS OVER WA STATE AND WEAK SFC CIRCULATION OVER MT. MAIN FORECAST CHALLENGE WILL BE PRECIP AND CHANCES FOR THUNDER AS ASSOCIATED FRONT PUSHES ACROSS THE FA. IN GENERAL...NAM AND GFS IN FAIR AGREEMENT WITH TIMING HOWEVER...AS USUAL...NAM IS A BIT DRIER. THUS GOING PRIMARILY WITH GFS. GFS SHOWS H700 LOW DEEPEN OVER NRN ROCKIES EARLY SUN...AND DEVELOPMENT OF DECENT BAND OF FRONTOGENESIS BY MID DAY SUNDAY. TIGHTENING SFC GRADIENT WILL RESULT IN SOUTHERLY FLOW PUMPING UP DEW POINTS DRG THE DAY SUN. SFC FRONT THEN PROGGED TO ENTER INTO THE WESTERN FA BY 12Z MON...WITH SHOWALTER INDICES AHEAD OF FRONT RANGING FROM NEG TWO TO NEG 4. BEST INSTABILITY LOOKS TO BE ALONG AND JUST EAST OF VALLEY AT 12Z MON...WITH RAPID RISE IN SHOWALTERS ACROSS THE EAST BY MON AFTERNOON. MAIN CHANGES TO PREV FCST ARE MINOR TWEAKS TO POPS AND TIMING OF FRONT. ELECTED TO NOT BUMP POPS INTO THE CHANCE CAT FOR 00Z TO 06Z MON AS MODELS FAIRLY CONSISTENT WITH KEEPING FRONT WELL TO WEST. BEYOND THAT...MADE MINOR ADJUSTMENTS FOR ORIENTATION OF FRONT HOWEVER DID ADJUST POPS BEHIND FRONT TO MOVE SYSTEM OUT IN LINE WITH 12Z GFS. ALSO CHANGED PRECIP TYPE BEHIND THE TIGHT SHOWALTER GRADIENT TO RAIN WITH ISOLATED THUNDER...VICE PREDOMINANTLY THUNDERSTORMS. LAST ISSUE WAS QPF...APPEARS BOTH HPC AND GFS LIKELY OVERDOING QPF AMOUNTS SO CUT AMOUNTS IN HALF. GFS AND ECMWF BOTH SHOW WEAK SFC LOW DEVELOP IN WRN DAKOTAS BEHIND THIS FRONT...WITH A CHANCE FOR MORE PRECIP IN CNTRL DAKOTA FOR TUE. DID INTRODUCE A SLIGHT CHANCE FOR RAIN SHOWERS IN MY SW. FOR TEMPS...NEWEST MAV GUIDANCE VERY MUCH IN LINE WITH PREV FCST AND MINOR ADJUSTMENTS WERE MADE. LONG TERM... /WED THROUGH SAT/ A BROAD 500 MB TROUGH ACROSS CANADA WILL RESULT IN BELOW NORMAL TEMPERATURES THROUGH THE EXTENDED PERIOD. A CHANCE OF PRECIPITATION RETURNS DURING THE THURSDAY INTO FRIDAY TIME PERIOD AS THE NEXT IN A SERIES OF COLORADO SURFACE CYCLONES TRACKS INTO THE NORTHERN PLAINS. 850 MB TEMPERATURES COOL BELOW 0C THURSDAY NIGHT INTO FRIDAY MORNING. THUS...A MIXTURE OF RAIN AND SNOW SHOWERS HAS BEEN INTRODUCED INTO THIS TIME PERIOD. FIRE WEATHER... CONDITIONS WILL REMAIN NEAR CRITICAL FIRE WEATHER CRITERIA OVER THE DEVILS LAKE BASIN THROUGH THE REST OF THIS AFTERNOON. TOWARDS EVENING...TEMPERATURES WILL COOL SUFFICIENTLY TO BRING RELATIVE HUMIDITIES UP. WINDS WILL GENERALLY REMAIN IN THE 5 TO 10 MPH RANGE WITH AN OCCASIONAL GUST TO 15. OTHERWISE...SOUTHERLY FLOW DEVELOPING THIS AFTERNOON AND EVENING WILL HELP TRANSPORT LOW LEVEL MOISTURE INTO THE CWA...AND WILL INCREASE AHEAD OF LOW PRESSURE DEVELOPING IN THE HIGHT PLAINS. THUS...MINIMUM HUMIDITIES SHOULD RISE INTO THE 32 TO 37 PERCENT RANGE FOR SUNDAY. AS THE GRADIENT TIGHTENS INTO SUNDAY...WINDS ARE EXPECTED TO INCREASE INTO THE 15 TO 20 MPH RANGE...WITH GUSTS OF 25 TO 30 MPH POSSIBLE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ RIDDLE/SPEICHER/HOPKINS nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 550 PM EDT SAT APR 19 2008 .SYNOPSIS... WEAKENING LOW PRESSURE OVER LOWER MICHIGAN WILL REMAIN NEARLY STATIONARY INTO SUNDAY AS A SECONDARY LOW PRESSURE AREA FORMS OVER VIRGINIA AND DRIFTS SLOWLY SOUTHEAST INTO NORTH CAROLINA ON MONDAY. HIGH PRESSURE OFF THE NEW ENGLAND COAST WILL REMAIN NEARLY STATIONARY AND SPREAD BACK SOUTHWESTWARD EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY/... THE REGION IS IN THE DEFORMATION ZONE ON THE EAST SIDE OF THE LOW TONIGHT AND AS THE LOW BECOMES NEGATIVELY TILTED A STRONG SE FLOW AT 850 MB TRIES TO TAP MOISTURE FROM THE MID ATLANTIC COAST AND SEND IT NW TOWARD NW PA BY SUNDAY. THE NAM IS MORE PRONOUNCED WITH THIS SE FLOW THAN THE GFS. BOTH THE GFS AND NAM PRODUCED A MOD TO LARGE AMOUNT UVM TONIGHT SO EXPECT NUMEROUS SHOWERS WITH ISOLATED THUNDER. HAVE ADJUSTED POPS FOR THIS EVENING TO SHOW HIGHER INITIAL POP FOR MORE LAKESHORE COUNTIES AND HAVE ADDED THUNDER FOR ALL BUT NW PA WHERE PRECIP PROB WL NOT OCCUR UNTIL AIRMASS HAS STABILIZED MORE LATER THIS EVENING. && .SHORT TERM /6 AM SUNDAY THROUGH MONDAY NIGHT/... THE CUT OFF LOW MAKES GRADUAL PROGRESS TO THE EAST JUST SOUTH OF THE REGION SUNDAY INTO MONDAY. SOME SUBSIDENCE IS INDICATED FROM SUNDAY OVER THE WESTERN COUNTIES SO I DON`T EXPECT MUCH MORE THAN A SCATTERED MORNING SHOWER. LIKELY POPS ARE IN STORE FOR THE EAST HALF WITH THE MOIST SE FLOW A LOW LEVELS PERSISTING. THE SE LOW LEVEL FLOW WILL WEAKEN MONDAY AND ALLOW SOME DRYING TO TAKE PLACE. GFS GUIDANCE SEEMS REASONABLE. && .LONG TERM /TUESDAY THROUGH SATURDAY/... SIDED WITH THE MORE CONSISTENT AND MUTUALLY AGREED UPON ECWMF FOR THE EXTENDED WHICH BRINGS A FRONT IN A WEAKENED STATE ACROSS WEDNESDAY AND THEN A MORE SIGNIFICANT FRONT FOR SATURDAY. WITH NO REAL CHILLY AIR BEHIND THE NEAR/SHORT TERM SYSTEM...HAVE HIGHS IN THE 70S FOR TUESDAY AND ONLY BACKING OFF A FEW FOR WED/THU. TEMPS CLIMB AGAIN FRI AS WED/THU FRONT WILL PROBABLY LIFT NORTHWARD AS A WARM FRONT. COLD FRONT SATURDAY. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... SURFACE AND UPPER LEVEL LOW CONTINUE TO SPIN AND MAKE SLOW ESE PROGRESS INTO THE OHIO VALLEY TODAY. SURFACE TROUGH/WIND SHIFT MOVED ACROSS FROM SW TO NE TURNING WINDS SOUTHWEST THIS MORNING. SE FLOW CONTINUES FOR NW PA. DRY AIR IN PLACE HAS MADE PRECIP IMPOSSIBLE THUS FAR ACROSS THE AREA. FOR THE REST OF THE AFTERNOON...FIRST CONCERN IS LAKE BREEZE. ATYPICAL TODAY WITH SOME SYNOPTIC INFLUENCE BUT LAKE BREEZE ALREADY AT DKK AND AND BKL. FOR ERI TROUGH/WIND SHIFT EMANATING FROM SFC LOW TO DISRUPT LAKE BREEZE SOMEWHAT AND HAVE WINDS COMING AROUND TO THE EAST-NE AT MOST. THEY MAY SWING EITHER WAY. FOR CLE WE MAY TEND MORE WEST THIS AFTERNOON WITH A POSSIBILITY THAT THE LAKE BREEZE WILL PULL US TO THE WNW. WIND FORECAST ON CURRENT CONDITIONS AND RUC FORECAST. ALL OF THIS RELAXES THIS EVENING AND WINDS AREA WIDE WILL PRETTY MUCH GO LIGHT/VARIABLE WITH THE BROAD AND WEAK LOW OVER OHIO. PREVAILING VFR CONDITIONS EVEN IF WE DO GET A FEW SHOWERS IN TO THE AREA THIS AFTERNOON. POSSIBILITY FOR A RUMBLE OF THUNDER BUT CHANCES SLIM AND THEREFORE NOT IN TAFS/EXCEPT FDY/. DELAYED THE START OF ANY SHRA. BEST CHANCES LOOK TO BE CENTRAL AND WESTERN PORTIONS AS MOISTURE/SHOWERS FROM CENTRAL OHIO AND ADDITIONAL DEVELOPMENT ACROSS WV IS EXPECTED. THIS AREA HAS NICE CONNECTION TO ATLANTIC FEED. ALSO ACROSS THE EAST CAPE VALUES WILL BE ABLE TO MOUNT SOME. VFR CIGS/VSBY TO GIVE WAY TO MVFR AS LOW GETS CLOSER...AFTER MIDNIGHT. HAVE CONTINUED WITH PREVIOUS FORECAST...TRENDED THE FORECAST TO SHOW POSSIBLE IFR CONDITIONS AFTER 06Z BUT CONFIDENCE IN THIS OCCURRING IS LOW. MAV GUIDANCE SHOWS LIFR CONDITIONS AT MOST SITES AT 12Z SUNDAY BUT THIS SEEMS TOO PESSIMISTIC GIVEN SOUTHWESTERLY FLOW AND CLIMATOLOGY TO THE CONTRARY. OUTLOOK...MVFR CIGS WILL BE POSSIBLE DURING THE DAY ON SUNDAY BUT SHOULD GIVE WAY TO VFR CONDITIONS ON MONDAY. COLD FRONT AND EXPECTED TO SWEEP THROUGH THE TERMINALS WEDNESDAY MORNING...COULD SEE BRIEF RESTRICTIONS TO MVFR/IFR ALONG THE FRONT BUT THIS SHOULD BE SHORT LIVED WITH VFR CONDITIONS RETURNING WEDNESDAY NIGHT. && .MARINE... LIGHT AND VARIABLE FLOW ON THE LAKE THIS AFTERNOON...WITH ONSHORE FLOW ALONG THE NEARSHORE REGION. SLOW MOVING WEAK SYSTEM MOVING THROUGH THE OHIO VALLEY WILL KEEP LGT/VARIABLE FLOW ACROSS THE LAKE THROUGH SUNDAY AND A CHANCE FOR SHOWERS. MORE UNIFORM ESE FLOW TO DEVELOP MONDAY AS A RIDGE BUILDS IN. COLD FRONT WEDNESDAY WILL BRIEFLY BRING WINDS AROUND THE DIAL TO THE NW AND NORTH AND TO ENE WITH HIGH PRESSURE FOR THURSDAY. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...REL NEAR TERM...ADAMS SHORT TERM...REL/ADAMS LONG TERM...OUDEMAN AVIATION...OUDEMAN MARINE...OUDEMAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 154 PM EDT SAT APR 19 2008 .SYNOPSIS... WEAKENING LOW PRESSURE OVER ILLINOIS WILL MOVE EASTWARD TO LOWER MICHIGAN BY TONIGHT. THE LOW WILL DRIFT SOUTHEAST ACROSS OHIO TONIGHT TO THE CENTRAL APPALACHIANS ON SUNDAY AND CAROLINA COAST ON MONDAY. HIGH PRESSURE WILL REMAIN NEARLY STATIONARY ACROSS EASTERN CANADA AND SPREAD BACK SOUTHWESTWARD EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CURRENT FORECAST LOOKS GOOD SO ONLY MINOR CHANGES PLANNED. MOSTLY SUNNY SKIES OVER NE OH AND NW PA WITH DOWNSLOPE SE FLOW HAS ALLOWED TEMPS TO RISE INTO THE 70S ALREADY. WILL RAISE TEMPS TO NEAR 80 THERE. PCPN ROTATING AROUND THE IL UPPER LOW IS HAVING TROUBLE FILLING IN AS BOUNDARY LAYER IS STILL RATHER DRY. A LARGER AREA OF SHOWERS OVER WV IS MOVING NORTH AND MAY REACH THE REGION BY MID AFTERNOON. HAVE DROPPED THE MENTION OF THUNDERSTORMS FOR THE AFTERNOON WITH LIMITED INSTABILITY. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... AS SYSTEM GETS TOTALLY CUT OFF THERE WILL ESSENTIALLY BE NO GULF INFLOW BY TONIGHT. PCPN WILL BECOME DEPENDENT STRICTLY ON UPWARD MOTION WHICH WILL BE ENHANCED AT NIGHT BY THE LOW LEVEL JET AND DURING THE DAY BY CONVECTIVE PROCESS. THE MAIN AREA OF SHOWERS SHOULD SHIFT OFF TO THE ESE LATER TONIGHT AND THROUGH THE DAY SUNDAY AS LARGE DRY SURFACE HIGH REMAINS BLOCKED OVER E CANADA AND UPPER LOW GETS KNUCKLED UNDER THE RIDGE TOWARD THE CAROLINAS. SHOULD SEE A FAIR AMOUNT OF CLOUDS LINGER ON SUNDAY WITH A GRADUAL THINNING INTO MONDAY. SHOWERS SHOULD DECREASE ACROSS NW OHIO TONIGHT. WILL NOT GO AS HIGH AS GFS GUIDANCE POPS ON SUNDAY FOR NE OH/NW PA. THE SHOWERS WILL REACH THE DEFORMATION ZONE ALOFT AND COULD LINGER IN THAT AREA BUT WITH DOWNSLOPE SSE FLOW CONTINUING AND THE VARIABILITY IN THE MODELS DO NOT HAVE ENOUGH CONFIDENCE TO PIN DOWN THAT PARTICULAR AREA AND WILL GENERALLY HAVE "CHANCE" POPS ON SUNDAY. AIRMASS WILL BE EXCHANGED IN MOST AREAS ON SUNDAY WITH THE POSSIBLE EXCEPTION OF NW PA AND SHOULD SEE COOLER TEMPS FILTER BACK TO ALL AREAS. AREAS THAT GET THE MOST SHOWERS WILL SEE TEMPS DEPRESSED THE MOST WHILE AREAS THAT HAVE LITTLE RAIN WILL SEE TEMPS SNEAK UP TOWARD THE UPPER 60S OR 70. MONDAY TRICKY IN THE FACT THAT THE AXIS OF HIGHER THETA E AND SURFACE TROUGH MAY LINGER. MY FIRST THOUGHT WAS THAT IT MIGHT GET CONVECTIVE AND NEW SHOWERS AND THUNDERSTORMS MIGHT POP UP. MODELS DO NOT SHOW MUCH INSTABILITY THOUGH. CANNOT RULE OUT A LINGERING SHOWER...MAINLY N CENTRAL AND NE OH. WILL CONTINUE WITH A 20 POP (SLIGHT CHANCE) ON MONDAY. ENOUGH SUBSIDENCE AND RIDGING BY TUESDAY THAT IT SHOULD BE DRY. TEMPS WILL REBOUND A CATEGORY OR TWO ON TUESDAY AS SOUTH FLOW GET REESTABLISHED. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... EXTENDED PORTION OF THE FORECAST STARTS WITH A COLD FRONTAL PASSAGE WEDNESDAY MORNING. THE ECMWF GFS AND GFS ENSEMBLE MEAN ALL MOVE THIS FRONT THROUGH THE FORECAST AREA BY WEDNESDAY AFTERNOON WITH HIGH PRESSURE RAPIDLY BUILDING BEHIND THE FRONT WEDNESDAY EVENING. MADE SOME ADJUSTMENTS TO THE FORECAST AND WENT WITH A MORE OPTIMISTIC APPROACH WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WITH STRONG HIGH PRESSURE EXPECTED TO BUILD SOUTHWARD FROM ONTARIO...WILL GO WITH A DRY FORECAST THROUGH THURSDAY EVENING. ALSO EXPECTING TO SEE A FAIR AMOUNT OF SUN DURING THE DAY ON THURSDAY AND DECREASED FORECAST CLOUD COVER. MODEL DISCREPANCIES MAKE THEMSELVES APPARENT THURSDAY NIGHT THROUGH THE END OF THE WEEK AS THE GFS MAINTAINS DRY CONDITIONS WHILE THE EURO BRINGS A WAVE UP THE OHIO VALLEY BY FRIDAY MORNING. THE ECMWF SOLUTION TENDS TO AGREE MORE WITH THE 18Z GFS...THUS MAKING THE 00Z GFS SOLUTION THE OUTLIER AND HAVE DISCARDED IT ACCORDINGLY. WILL MAINTAIN CHANCE POPS DURING THE DAY ON FRIDAY. WHILE THE 00Z GFS SHOWS A DECAYING COLD FRONT SWEEPING THROUGH OHIO/PENNSYLVANIA FRIDAY...AM HESITANT TO BITE OFF ON THIS SOLUTION ENTIRELY GIVEN THE VARIETY OF MODEL SOLUTIONS. && .AVIATION /17Z SATURDAY THROUGH WEDNESDAY/... SURFACE AND UPPER LEVEL LOW CONTINUE TO SPIN AND MAKE SLOW ESE PROGRESS INTO THE OHIO VALLEY TODAY. SURFACE TROUGH/WIND SHIFT MOVED ACROSS FROM SW TO NE TURNING WINDS SOUTHWEST THIS MORNING. SE FLOW CONTINUES FOR NW PA. DRY AIR IN PLACE HAS MADE PRECIP IMPOSSIBLE THUS FAR ACROSS THE AREA. FOR THE REST OF THE AFTERNOON...FIRST CONCERN IS LAKE BREEZE. ATYPICAL TODAY WITH SOME SYNOPTIC INFLUENCE BUT LAKE BREEZE ALREADY AT DKK AND AND BKL. FOR ERI TROUGH/WIND SHIFT EMANATING FROM SFC LOW TO DISRUPT LAKE BREEZE SOMEWHAT AND HAVE WINDS COMING AROUND TO THE EAST-NE AT MOST. THEY MAY SWING EITHER WAY. FOR CLE WE MAY TEND MORE WEST THIS AFTERNOON WITH A POSSIBILITY THAT THE LAKE BREEZE WILL PULL US TO THE WNW. WIND FORECAST ON CURRENT CONDITIONS AND RUC FORECAST. ALL OF THIS RELAXES THIS EVENING AND WINDS AREA WIDE WILL PRETTY MUCH GO LIGHT/VARIABLE WITH THE BROAD AND WEAK LOW OVER OHIO. PREVAILING VFR CONDITIONS EVEN IF WE DO GET A FEW SHOWERS IN TO THE AREA THIS AFTERNOON. POSSIBILITY FOR A RUMBLE OF THUNDER BUT CHANCES SLIM AND THEREFORE NOT IN TAFS/EXCEPT FDY/. DELAYED THE START OF ANY SHRA. BEST CHANCES LOOK TO BE CENTRAL AND WESTERN PORTIONS AS MOISTURE/SHOWERS FROM CENTRAL OHIO AND ADDITIONAL DEVELOPMENT ACROSS WV IS EXPECTED. THIS AREA HAS NICE CONNECTION TO ATLANTIC FEED. ALSO ACROSS THE EAST CAPE VALUES WILL BE ABLE TO MOUNT SOME. VFR CIGS/VSBY TO GIVE WAY TO MVFR AS LOW GETS CLOSER...AFTER MIDNIGHT. HAVE CONTINUED WITH PREVIOUS FORECAST...TRENDED THE FORECAST TO SHOW POSSIBLE IFR CONDITIONS AFTER 06Z BUT CONFIDENCE IN THIS OCCURRING IS LOW. MAV GUIDANCE SHOWS LIFR CONDITIONS AT MOST SITES AT 12Z SUNDAY BUT THIS SEEMS TOO PESSIMISTIC GIVEN SOUTHWESTERLY FLOW AND CLIMATOLOGY TO THE CONTRARY. OUTLOOK...MVFR CIGS WILL BE POSSIBLE DURING THE DAY ON SUNDAY BUT SHOULD GIVE WAY TO VFR CONDITIONS ON MONDAY. COLD FRONT AND EXPECTED TO SWEEP THROUGH THE TERMINALS WEDNESDAY MORNING...COULD SEE BRIEF RESTRICTIONS TO MVFR/IFR ALONG THE FRONT BUT THIS SHOULD BE SHORT LIVED WITH VFR CONDITIONS RETURNING WEDNESDAY NIGHT. && .MARINE... LIGHT FLOW ON THE LAKE TODAY WITH NORTHEASTERLY WINDS EVENTUALLY BECOMING SOUTHEASTERLY LATE TONIGHT. SURFACE AND UPPER LEVEL LOW PRESSURE EXPECTED TO MOVE OVERHEAD AND DISSIPATE SUNDAY AFTERNOON WHILE HIGH PRESSURE BUILDS ACROSS THE LAKE FROM THE NORTH. WINDS WILL RETURN TO NORTHEASTERLY LATE SUNDAY NIGHT AND MAINTAIN AN EASTERLY COMPONENT THROUGH TUESDAY. LOW PRESSURE AND A COLD FRONT WILL APPROACH LAKE ERIE FROM THE WEST WEDNESDAY MORNING WITH WINDS VEERING TO SOUTHERLY TUESDAY NIGHT...THEN COMING AROUND OUT OF THE WEST WEDNESDAY AFTERNOON. AT THIS POINT GIVEN THE TIMING OF THE FRONT AND ITS WEAK NATURE...NOT EXPECTING WINDS TO REACH SMALL CRAFT ADV CRITERIA. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KOSARIK NEAR TERM...REL SHORT TERM...KOSARIK LONG TERM...LEINS AVIATION...OUDEMAN MARINE...LEINS oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 925 AM CDT SAT APR 19 2008 .UPDATE... WILL GO AHEAD AND SEND AN UPDATE TO ADDRESS SOME CHANGES MADE TO THE GRIDS WRT TO TEMPS AND WINDS TODAY ALONG WITH SOME CHANGES TO MIXING HEIGHTS/TRANSPORT WINDS FOR FIRE WX. MUCH OF THE CHANGES BASED ON MORNING TRENDS AND LATEST RUC FORECAST. UPDATES OUT SHORTLY. 30 ----------------------------------------------------------- 502 AM CDT SAT APR 19 2008 .DISCUSSION... WARMER TEMPERATURES AND DRY WEATHER ARE EXPECTED TODAY AS SOUTH WINDS RETURN TO THE REGION WHILE AN UPPER LEVEL RIDGE TRANSLATES ACROSS SOUTHERN PLAINS. SKIES WILL START OUT CLEAR THIS MORNING ALTHOUGH SOME CIRRUS MAY SPREAD INTO THE SOUTHWEST PART OF THE AREA THIS AFTERNOON. SOUTH WINDS WILL INCREASE QUITE A BIT ON SUNDAY OVER MUCH OF THE AREA AS THE LEE TROUGH DEEPENS TO OUR WEST. THE WINDS WILL BEGIN TO PULL MORE MOISTURE... AND SOME LOWER CLOUDS... NORTH INTO THE AREA BY LATE IN THE DAY. THE DRYLINE IS ALSO FORECAST TO BECOME BETTER DEFINED NEAR THE WESTERN OK-TX PANHANDLE BORDER IN RESPONSE TO VEERING WINDS OVER WEST TEXAS AND THE MOISTURE RETURN TO THE EAST. ALTHOUGH THE WINDS WILL BE INCREASING THROUGH THE WEEKEND... UNCERTAINTY REMAINS REGARDING HOW SIGNIFICANT THE FIRE WEATHER CONCERNS WILL BE FOR OUR FAR WESTERN TIER OF COUNTIES. FOR THIS AFTERNOON... THE MINIMUM HUMIDITIES WILL LIKELY BE NEAR OR BELOW 20 PERCENT IN THE FAR WEST BUT THOSE AREAS MAY NOT REACH WIND SPEED CRITERIA UNTIL RATHER LATE IN THE AFTERNOON. FOR SUNDAY... THERE IS STILL UNCERTAINTY CONCERNING THE EXACT LOCATION OF WHERE THE DRYLINE WILL SET UP. THE ECMWF LIKELY IS MIXING THE MOISTURE OUT TOO FAR TO THE EAST...WHILE THE GFS AND NAM MIGHT BE JUST A BIT TOO MOIST IN THE FAR WEST. THE NAM WAS ALSO LOWERING THE WIND SPEEDS NEAR AND BEHIND THE DRYLINE IN THE AFTERNOON. FOR NOW... WE DO NOT PLAN TO ISSUE A WATCH. FARTHER WEST... A LARGE UPPER TROUGH WILL BE SETTLING INTO THE WESTERN U.S. THROUGH THE WEEKEND AND WILL BEGIN SPREADING ITS INFLUENCE INTO THE SOUTHERN PLAINS BY LATE SUNDAY. CONCERNING THE T-STORM CHANCES FOR THE UPCOMING WEEK... THE EARLIEST POSSIBILITY FOR STORMS WOULD BE LATE SUNDAY NEAR THE DRY LINE. HOWEVER... MODEL SOUNDINGS SUGGEST THAT MOISTURE WILL STILL BE RATHER SHALLOW... WHILE A MID LEVEL CAP STRENGTHENS OVER THE AREA. A LEAD SHORT WAVE MOVING OUT OF THE WESTERN TROUGH WILL LIKELY BE TOO FAR NORTH TO CONTRIBUTE MUCH UPPER SUPPORT. GIVEN THESE FACTORS... WE WILL NOT MENTION STORMS FOR SUNDAY. ANOTHER UPPER WAVE MAY BRUSH NORTH CENTRAL OKLAHOMA MONDAY NIGHT WHICH COULD RESULT IN A FEW STORMS IN THAT AREA. T-STORM CHANCES INCREASE A BIT MORE WEDNESDAY AND THURSDAY AS A FRONT MOVES INTO THE REGION. SINCE CONFIDENCE IN THE MODELS STARTS TO FALL OFF ABOUT THIS TIME... SO WILL NOT GET TOO CARRIED AWAY WITH POPS AT THIS POINT. REGARDING THE DECREASING CONFIDENCE IN THE MODELS BY MIDWEEK... THE GFS AND ECMWF 500 MB PATTERNS START TO MOVE OUT OF PHASE FROM EACH OTHER BY THAT TIME. THE ECMWF HOLDS ONTO A BROAD TROUGH OVER THE WESTERN U.S. WHILE THE OPERATIONAL GFS IS PROGRESSIVE WITH MOVING AN UPPER RIDGE INTO THE WESTERN US. THE OPERATIONAL GFS ALSO HAS MUCH MORE AMPLITUDE IN A WAVE THAT MOVES INTO THE UPPER MIDWEST TUESDAY NIGHT WHILE THE ECMWF DAMPENS THE WAVE QUITE A BIT. THE NET RESULT OF THESE DIFFERENCES IS THAT THE GFS PUSHES A STRONGER COLD FRONT SOUTH INTO THE SOUTHERN PLAINS. THE MEX GUIDANCE REFLECTS THIS SOLUTION IN COOLING TEMPERATURES SEVERAL DEGREES IN MANY LOCATIONS FOR THE PERIOD TUES NIGHT THROUGH EARLY FRI AS COMPARED TO THE PAST MODEL RUNS. THE CONFIDENCE IN THIS SOLUTION IS NOT HELPED BY THE FACT THAT THE GFS ENSEMBLE MEMBERS EXHIBIT SIGNIFICANT VARIABILITY IN THIS TIME PERIOD WHILE THE ENSEMBLE MEAN HEIGHTS DO INDICATE A LOW AMPLITUDE TROUGH TO OUR WEST... A SOLUTION THAT MORE CLOSELY MIRRORS THE ECMWF RATHER THAN THE OPERATIONAL GFS. GIVEN THE UNCERTAINTIES SURROUNDING THE NEW TREND OF THE GFS TO DEPICT GREATER COOLING NEXT WEEK AND THAT MOST OF OUR SURROUNDING OFFICES ARE HANGING ON TO WARMER TEMPERATURES FOR NOW... WE WILL DISCARD THIS PART OF THE MEX TEMPERATURE GUIDANCE AND KEEP THE CURRENT TEMPERATURE FORECAST FOR MID WEEK. WE WILL ALSO ADJUST WIND DIRECTIONS MORE CLOSELY MATCH TO THE ECMWF GUIDANCE. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 79 53 78 58 / 0 10 10 10 HOBART OK 81 54 82 57 / 0 10 10 10 WICHITA FALLS TX 83 55 83 62 / 0 10 10 10 GAGE OK 84 48 84 48 / 0 10 10 10 PONCA CITY OK 76 51 79 60 / 0 10 10 10 DURANT OK 80 54 80 64 / 0 0 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 26/32 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1030 AM CDT FRI APR 18 2008 .UPDATE... MADE A FEW MINOR TWEAKS TO TODAYS GRIDS BASED ON MORNING RUC13. THIS RESULTED IN A COUPLE DEGREES WARMER IN MANY LOCATION FOR THIS AFTN. OTHERWISE WINDS SHOULD DECREASE SOME THIS AFTN...BUT ARE EXPECTED TO PICK BACK UP OUT OF THE SOUTH OVER THE WEEKEND WITH MUCH WARMER TEMPS. UPDATES OUT SHORTLY. 30 ----------------------------------------------- 354 AM CDT FRI APR 18 2008 .DISCUSSION... THE STRONG UPPER WAVE OVER OK AND WESTERN NORTH TEXAS EARLY THIS MORNING WILL REACH THE MISSISSIPPI VALLEY BY LATE TODAY. WITH THE FORCING ASSOCIATED WITH THIS SYSTEM EXITING THE AREA... THE SHOWERS HAVE MOVED EAST OUT OF THE CWA. MEANWHILE... THE CLOUDS WILL CONTINUE TO GRADUALLY CLEAR FROM THE WEST DURING THE DAY. THIS MORNING WILL START OFF WITH BREEZY AND COOL WITH TEMPERATURES IN THE MID 30S IN NORTHWEST OKLAHOMA AND 40S ELSEWHERE. TEMPERATURES BY LATE AFTERNOON WILL GENERALLY RANGE FROM THE LOWER 60S IN THE FAR EAST TO THE LOWER HALF OF THE 70S IN THE WEST. DRY AND WARMER WEATHER IS EXPECTED OVER THE WEEKEND AS AN UPPER RIDGE MOVES THROUGH THE PLAINS AND SOUTH WINDS RETURN. ALTHOUGH THE LATEST GFS MOS GENERATES SOME LOW POPS FOR SATURDAY NIGHT... WE WILL STAY WITH THE GOING FORECAST OF DRY WEATHER. IT APPEARS THAT THE UNSTABLE MOIST LAYER AVAILABLE TO GENERATE RAIN WILL BE VERY HIGH-BASED WITH A DEEP LAYER OF DRY AIR BENEATH IT. THE GFS GRIDDED FIELDS ALSO DO NOT GENERATE ANY QPF. LOW LEVEL MOISTURE SHOULD BEGIN TO RETURN TO THE AREA BY LATE SUNDAY WHILE A DRYLINE SETS UP OVER THE FAR WESTERN PART OF THE CWA. EVEN THOUGH THE UPPER RIDGE HAS MOVED EAST OF THE AREA BY THAT TIME... THUNDERSTORM CHANCES WILL LIKELY REMAIN LOW DUE TO A FAIRLY SUBSTANTIAL CAP THAT DEVELOPS. MEANWHILE... THE INCREASE OF LOW LEVEL CLOUDS ON SUNDAY IN RESPONSE TO DEEPER MOISTURE RETURN MAY KEEP TEMPERATURES A FEW DEGREES COOLER OVER THE EASTERN PART OF THE CWA. IN THE LONGER TERM... A LARGE... COMPLEX UPPER WAVE DIGGING INTO THE WESTERN U.S. OVER THE WEEKEND WILL PROVIDE A FEW CHANCES FOR T-STORMS NEXT WEEK ALTHOUGH THE EXACT TIMING OF THE VARIOUS ENERGY PULSES BEING EJECTED OUT OF THE UPPER WAVE IS UNCERTAIN. WHILE A FEW STORMS WILL BE POSSIBLE LATE MONDAY AND TUESDAY... IT APPEARS THAT THE BETTER CHANCES WILL BE WEDNESDAY AND THURSDAY AS A SLOW MOVING COLD FRONT DROPS INTO THE AREA. WE HAVE ADJUSTED THE GFS MOS HIGH TEMPERATURE GRIDS FOR TUE/WED DOWNWARD ACROSS NORTHWEST OKLAHOMA TO REFLECT GFS GRID SOLUTION OF PUSHING THE COLD FRONT INTO THE AREA. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 66 42 78 56 / 0 0 0 10 HOBART OK 67 42 82 56 / 0 0 0 10 WICHITA FALLS TX 73 45 83 58 / 0 0 0 10 GAGE OK 72 36 84 50 / 0 0 0 10 PONCA CITY OK 62 41 76 57 / 10 0 0 10 DURANT OK 66 48 80 60 / 0 0 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 26/32 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1036 PM EDT SAT APR 19 2008 .SYNOPSIS... AN AREA OF HIGH PRESSURE OVER NOVA SCOTIA WILL HELP TO PROVIDE A PERSISTENT SOUTHEASTERLY FLOW OF AIR OVER THE NEXT FEW DAYS AND INCREASE THE CHANCE FOR SHOWERS AS UPPER LOW PRESSURE SLOWLY DRIFTS ACROSS THE CENTRAL APPALACHIANS. SOME PORTIONS OF SOUTH CENTRAL PENNSYLVANIA AND THE LAUREL HIGHLANDS COULD SEE AN INCH OR TWO OF RAINFALL OVER THE NEXT 48 HOURS. COOLER AND UNSETTLED WEATHER WILL ACCOMPANY THIS LOW PRESSURE SYSTEM FOR THE LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... BANDS OF SHOWERS (SOME BRIEFLY HEAVY) WERE TRAINING NNWD AND ACROSS THE LAUREL HIGHLANDS ATTM. 12 KM NAM AND 13 KM RUC APPEAR TO BEE AT LEAST SEVERAL HOURS TOO SLOW AND LIKELY TOO LIGHT WITH THE QPF FROM THESE RAIN BANDS. INCREASED POPS ACROSS THE WRN MTNS AND SCENT ZONES AFTER MIDNIGHT TO LIKELY OR CATEGORICAL WITH AROUND ONE QUARTER OF AN INCH EXPECTED BY 12Z ACROSS THE LAUREL HIGHLANDS. MINOR DOWNWARD ADJUSTMENTS MADE TO TEMPS...AS RAIN STARTS TO COOL THE VERY DRY LOW TO MID LEVELS ACROSS THE SOUTH AND WEST LATE TONIGHT. && .SHORT TERM /SUNDAY NIGHT/... CONTINUED SLOW EASTWARD PROGRESSION OF UPPER LVL LOW. LATEST SOLUTIONS BEGINNING TO SLIDE SHORTWAVE TO THE SE SUN MORNING...WITH A CENTER OVER EXTREME SE KY BY SUNRISE. THIS WILL AID IN SLIDING THE BEST PRECIP CHANCES FURTHER SOUTH...MAINLY ALONG AND SOUTH OF I-80. FEEL THAT WITH THE WEAK RIDGE SLIDING OVERTOP FROM QUEBEC...THIS WILL AID IN STEERING VORT FURTHER SE AND MAY EVEN FILTER IN SOME DRY LOW/MID-LVL MOISTURE. HAVE MAINTAINED CATEGORICAL POPS GIVEN CONSISTENCY AND PROXIMITY OF LLJ...DESPITE LATEST BUMP IN TRACK TO THE SOUTH. MIXED LYR SHOULD TAP PORTION OF LLJ...SO COULD SEE GUSTS UP TO 30MPH IN NUMEROUS LOCATIONS. SREF PLUMES PROGGED A FOCUS OF 1.00 INCH FOR STATE COLLEGE THRU SUN NIGHT...WITH 1-1.5 TOWARDS MASON-DIXON LINE...HOWEVER THIS APPEARS TO BE A CONVERGENCE DRIVEN EVENT VS. A CONVECTIVE DRIVEN EVENT. ATTM DUE TO THE LONG DURATION OF THE EVENT...QPF TOTALS SHUD NOT POSE ANY HYDROLOGIC CONCERNS. WILL STILL CLOSELY MONITOR THE THREAT FOR LOCALIZED...TRAINING HEAVY RAIN BANDS/MINOR SMALL STREAM AND POOR DRAINAGE FLOODING... ESPECIALLY ACROSS SCENT PENN DURING THE MIDDAY AND AFTERNOON HOURS SUNDAY. THE PAST FEW RUNS OF THE NAM HAVE PAINTED THE POTENTIAL FOR 1.5 TO 2 INCHES OF RAIN IN A 12 HOUR PERIOD FROM NEA KAOO...SSE TO KMRB AND KHGR. && .LONG TERM /MONDAY THROUGH SATURDAY/... BEST CHC OF RAIN WL SHIFT TO S PA MONDAY. AFTER TUESDAY AFTERNOON...THINK ANY RAIN FROM CUTOFF WOULD BE SOUTH OF C PA. SOME SHOWERS LATE WED INTO THU WITH NEXT FRONT...BUT NOT LOOKING LIKE A STRONG FRONT...BEST CHC FOR SHOWERS WILL BE WESTERN SECTIONS. CHC OF SHOWERS FOR NEXT FRIDAY...BUT A WAYS OUT...SOME TIMING CONCERNS WITH THAT FRONT. FOR NOW...JUST WENT WITH A CHC... MAINLY THE GMOS WITH SOME MINOR ADJUSTMENTS. TEMPS WILL BE ABOVE NORMAL FOR THE MOST PART INTO LATE NEXT WEEK...BUT CLDS ON SUNDAY INTO MONDAY WILL HOLD DOWN TEMPS CLOSER TO NORMAL. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... GRADUAL INCREASE IN MOISTURE WILL MEAN A GRADUAL DECREASE IN FLIGHT CONDITIONS OVER THE NEXT 6-12 HOURS. EXPECTED ALL STATIONS TO BE IFR/MVFR BY MORNING...WITH PROBABLY A SLOW LIFT BACK UP TO MVFR BY AFTERNOON. BUT THE SLOW MOVING UPPER LOW WILL KEEP LESS THAN VFR WEATHER IN THE AREA INTO MONDAY AT LEAST. DRIER AIR SHUD BUILD IN LATER MON-TUES...BUT THE CEILINGS MAY BE STUBBORN TO GO AWAY AS WE WILL SEE A DEEP EASTERLY FLOW DEVELOP THRU MID WEEK. IT ALL POINTS TO ONLY SLOW CHANGES FOR THE NEXT SEVERAL DAYS...BUT UNFORTUNATELY...ONCE THINGS DETERIORATE...THEY COULD STAY THAT WAY FOR A WHILE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT/BEACHLER NEAR TERM...LAMBERT/BEACHLER SHORT TERM...LAMBERT/BEACHLER LONG TERM...BEACHLER/MARTIN AVIATION...LACORTE pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 1039 AM CDT SAT APR 19 2008 .UPDATE... CURRENT FORECAST ON TRACK. TEMPERATURES WARMING TO FORECAST HIGH STILL ON TRACK. A PLEASANT DAY SHAPING UP. WIND WILL NEED TO BE WATCHED THIS AFTERNOON ESPECIALLY IN THE WEST BUT LATEST RUC SHOWS WIND FORECAST STILL LOOKS GOOD. NO CHANGES WILL BE MADE EXCEPT TO ADJUST RATE OF WARMING. && .PREV DISCUSSION... .SHORT TERM...THROUGH MONDAY MORNING SEVERAL ISSUES THIS FORECAST CYCLE...MAINLY PERTAINING TO FIRE WEATHER. DEW POINTS ACROSS THE REGION ARE IN THE LOW 30S/UPPER 20S...ONLY A FEW DEGREES HIGHER THAN THIS TIME YESTERDAY. WITH SURFACE HIGH MOVING EASTWARD...SOUTHEAST WINDS WILL BEGIN TO TAP SLIGHTLY MORE HUMID AIR OVER THE MIDWEST. THE LAG BETWEEN DEVELOPMENT OF GUSTY SURFACE WINDS AND INCREASED MOISTURE ADVECTION JUST HAPPENS TO BE DURING PEAK HEATING IN CENTRAL/NORTH CENTRAL COUNTIES. THE RESULT WILL BE AN INCREASED GRASSLAND FIRE THREAT. CONTINUE TO SUPPORT DEW POINTS IN FORECAST THAT ARE BELOW MODEL GUIDANCE...WHICH HAS BEEN A TREND FOR MOST OF THE WEEK. GIVEN THAT...HUMIDITY VALUES REMAIN TOO MARGINAL FOR RED FLAG WARNING...AND WILL FORGO ISSUANCE. INCREASED MOISTURE SUNDAY WOULD HELP MITIGATE FIRE WEATHER THREAT...HOWEVER SURFACE WINDS OF +40KTS WILL OFFSET THE HIGHER RH VALUES. H85 TEMPERATURES TODAY TO RANGE BETWEEN +15C TO +6C FROM WEST TO EAST...AND INCREASE TO +18C TO +9C FROM WEST TO EAST TOMORROW. THESE WARMER TEMPERATURES EASILY TRANSLATE TO THE SURFACE AS HIGHS IN THE 70S. WITH A LOW LEVEL JET PRESENT ACROSS THE REGION...THE +50KTS OR SO WILL SUPPORT VERY WARM OVERNIGHT TEMPERATURES TONIGHT. WILL CONTINUE TO ADVERTISE CHANCE POPS AS LAPSE RATES STEEPEN ACROSS WESTERN COUNTIES IN THE LATE AFTERNOON SUNDAY...THOUGH OVERALL MOISTURE REMAINS LIMITED. BETTER CHANCE EARLY MONDAY AS COLD FRONT AND UPPER TROUGH MOVE ACROSS REGION...WILL SEE CAPE VALUES UP TO 500 J/KG AND MARGINALLY NEGATIVE LI VALUES. .LONG TERM...MONDAY THROUGH FRIDAY A SURFACE BOUNDARY WILL PUSH INTO WESTERN MINNESOTA ON MONDAY BEFORE STALLING OUT AND WAITING IN ANTICIPATION OF MORE ENERGY ALOFT FOR MONDAY NIGHT AND TUESDAY. WILL MAINTAIN MENTION OF THUNDER FOR MONDAY MORNING DUE TO ELEVATED INSTABILITY IN VICINITY OF ADVANCING FRONT. BUT FOR LATER IN THE DAY MONDAY THROUGH TUESDAY WILL LEAVE PCPN AS SHOWERS WITH NO THUNDER MENTION AS PROGS SHOW FAIRLY STABLE ATMOSPHERE IN PLACE. THE EMPHASIS FOR PCPN MONDAY NIGHT AND TUESDAY WILL COME FROM A WAVE THAT MOVES OUT OF THE ROCKIES AND ACROSS THE REGION. EVEN A NICE LOOKING JET MAX IS PROGGED BY THE GFS TO CROSS THE REGION. AFTER TUESDAY FORECAST CONFIDENCE WANES DRASTICALLY WITH ECMWF AND GFS AT ODDS ON EVOLUTION OF THE MID LEVEL PATTERN. ECMWF MAINTAINS A BROAD WESTERN AND CENTRAL CONUS TROF...WHILE THE GFS/UKMET INDICATE RIDGING. TEMPERATURES WERE AN AMALGAM OF INHERITED GRIDS/00Z MEX GUIDANCE. && .AVIATION... VFR CONDITIONS ARE EXPECTED THROUGH THE NEXT 24 HOURS WITH ANY CLOUDS GENERALLY ABOVE 10K FEET WITH UNRESTRICTED VSBYS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...KEEFE SHORT TERM...CONNELLY LONG TERM...TDK AVIATION...TMT WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 255 PM CDT SAT APR 19 2008 .SHORT TERM...THROUGH TUESDAY NIGHT FORECAST CONCERNS WERE PRIMARILY FOCUSED ON FOG POTENTIAL TONIGHT...THEN RAIN CHANCES MONDAY AFTERNOON INTO TUESDAY. LOW PRESSURE AT THE SURFACE AND ALOFT WAS MOVING SLOWLY ACROSS OHIO VALLEY THIS AFTERNOON. EFFECTS OF THIS SYSTEM MANIFESTED BY CLOUD SHIELD WRAPPING OVER THE UPPER MISSISSIPPI VALLEY. EXCEPT FOR A FEW LINGERING PATCHES OF LIGHT RAIN OR DRIZZLE...PRECIPITATION HAD ENDED. ATMOSPHERE STILL MOIST BENEATH CLOUDS COVER...AS EVIDENCED BY RELATIVELY CLOSE TEMPERATURE/DEW POINT SPREADS. FURTHER UPSTREAM... ANOTHER MID LEVEL CIRCULATION WAS LOCATED OVER PACIFIC NORTHWEST. 19.12Z DETERMINISTIC NCEP AND EUROPEAN MODELS WERE IN GOOD AGREEMENT ON OVERALL SYNOPTIC SCALE FEATURES THROUGH EARLY PART OF THE WEEK. THUS...FORECAST CONFIDENCE WAS HIGH THAT THE FORECAST AREA SHOULD RECEIVE ANOTHER RAINFALL EVENT MONDAY AFTERNOON INTO TUESDAY. ONLY MODEL DIFFERENCES THAT MAY HAVE AN IMPACT ON SENSIBLE WEATHER WOULD BE 850MB TEMPERATURES ON MONDAY. NAM/WRF HAD WARMEST VALUES... WHICH WAS REFLECTED IN HIGHEST VALUES OF THE MOS GUIDANCE SUITE. TONIGHT INTO SUNDAY MORNING...ATMOSPHERE PRIMED FOR FOG DEVELOPMENT DUE TO MOIST BOUNDARY LAYER AND LIGHT WINDS. CAVEAT TO THIS WILL BE CURRENT CLOUD COVER AND WHETHER OR NOT THERE WILL BE SUFFICIENT BREAKS IN THE CLOUDS AND/OR CLEARING TO ALLOW FOR RADIATIONAL COOLING. LATEST RUC...NAM/WRF AND GFS SUGGEST RELATIVELY DRIER AIR SHOULD WRAP WESTWARD INTO THE FORECAST AREA...EXCEPT MOST LOCATIONS WEST OF THE MISSISSIPPI RIVER. AS A RESULT...THERE COULD BE AREAS OF DENSE FOG...ALTHOUGH UNCERTAINTY EXISTS ABOUT HOW WIDESPREAD IT COULD BE. AT THIS TIME...OPTED TO MAINTAIN SPIRIT OF CURRENT DATA BASE. MONDAY INTO TUESDAY...LATEST DATA SUITE SUPPORTED PREVIOUS MODEL TRENDS WITH REGARD TO COLD FRONTAL PASSAGE OCCURRING LATE MONDAY NIGHT INTO THE EARLY MORNING HOURS OF TUESDAY. TONGUE OF SURFACE DEW POINTS IN THE 50S ALONG THE FRONT EXPECTED TO INTERACT WITH LOW LEVEL THETA-E CONVERGENCE...ALONG WITH UPPER LEVEL DIVERGENCE...TO PROVIDE SUFFICIENT FORCING TO TRIGGER CONVECTION. TIMING OF FRONT AND ONSET OF FORCING SUGGESTS RAIN CHANCES BEGIN MONDAY AFTERNOON...WITH RAIN CHANCES INCREASING INTO LIKELY CATEGORY MONDAY NIGHT INTO TUESDAY. WITH RESPECT TO SEVERE WEATHER POTENTIAL...HIGHEST 0-6KM WIND SHEAR VALUES RESIDE IN POST-FRONTAL ENVIRONMENT. MEANWHILE...NARROW AXIS OF 0-3KM CAPE OF 1000-1500J/KG BUILDS WEST OF THE MISSISSIPPI RIVER MONDAY AFTERNOON AND EVENING. PER CURRENT SPC DAY 3 OUTLOOK...SLIGHT RISK OF SEVERE STORMS WAS ACROSS PARTS OF SOUTHEAST MN AND NORTHEAST IOWA. THIS APPEARS REASONABLE...ALTHOUGH HIGHEST THREAT MAY EVEN BE FURTHER WEST IN CLOSER PROXIMITY TO FRONT AND HIGHEST WIND SHEAR. BASED ON NAM/WRF 850MB TEMPERATURE FORECAST AROUND 12C AHEAD OF COLD FRONT ON MONDAY...NAM/WRF MOS GUIDANCE HAD WARMEST MAXIMUM TEMPERATURES COMPARED TO NGM AND GFS DATA SUITE. ACCORDING TO TIME/HEIGHT CROSS SECTIONS AND PLAN VIEW OF RELATIVE HUMIDITY...THERE SHOULD BE SUFFICIENT SOLAR INSOLATION TO ALLOW WARM SECTOR HEATING. THUS...OPTED TO NUDGE MAXIMUM TEMPERATURES UPWARD AREAWIDE MONDAY. .LONG TERM...WEDNESDAY THROUGH SATURDAY PRIMARY FOCUS WAS ON RAIN CHANCES FROM THURSDAY INTO FRIDAY. DETERMINISTIC AND PROBABILISTIC DATA CONTINUED TO SUPPORT A CONSISTENT SIGNAL FOR AN UPPER LEVEL AND SURFACE WAVE TO AFFECT THE UPPER MISSISSIPPI VALLEY. AS A RESULT...ANOTHER RAINFALL EVENT APPEARS TO BE IN STORE FOR THE AREA. CURRENT LOW-END RAIN CHANCES IN THIS TIME FRAME WILL PROBABLY WARRANT AN UPGRADE BASED ON POTENTIALLY STRONG DYNAMICS INTERACTING WITH RICH BOUNDARY LAYER MOISTURE. FOR NOW...NO CHANGES WERE MADE TO THIS PORTION OF THE EXTENDED OUTLOOK. && .AVIATION... FOCUS FOR NEXT 24-30 HOURS WILL BE TREND OF LOW CLOUD AND FOG ACROSS THE AREA. LOW STRATUS ALONG WITH DRIZZLE/FOG IN DEFORMATION AREA ON THE NORTHWEST SIDE OF THE DEPARTING SYSTEM. VISIBLE SATELLITE IMAGERY SHOWING SOME BREAKS WHERE DRY AIR ENTRAINED INTO THE OCCLUSION OVER EASTERN HALF OF WI...AND ALSO BREAKS ON THE WESTERN FRINGE OF THE CLOUD SHIELD OVER MN/IA. MODEL SOLUTIONS SUGGEST MOISTURE TO LINGER OVER THE AREA TONIGHT... AND THIS LOOKING ON TARGET...ESPECIALLY GIVEN ALL OF THE RAIN THAT HAS FALLEN RECENTLY. WOULD EXPECT MAINLY BROKEN CONDITIONS OVER THE EAST...IN THE VFR CATEGORY INITIALLY. BUT EXPECT SOME FOG DEVELOPMENT WHICH COULD MORPH INTO LIFR IN FOG/STRATUS AGAIN. OVER THE WEST...EXPECT AREAS THAT CLEAR JUST AHEAD OF THE SLOWLY ADVANCING RIDGE AXIS...TO SOUP IN WITH FOG AND STRATUS. AREAS THAT STAY UNDER THE THICKER CLOUD COVER MAY ACTUALLY SEE THE HIGHEST VISIBILITY. FOR THE TAF FORECASTS AT 18Z...OPTED TO GO ON THE PESSIMISTIC SIDE...WITH LIFR. THIS IN LINE WITH MOS GUIDANCE. WOULD EXPECT SOME IMPROVEMENT PRIOR TO THE NOON HOUR TOMORROW...SO THE LATER PERIODS OF THE TAFS WILL START SHOWING THIS IMPROVEMENT. && .HYDROLOGY... SIGNIFICANT RAIN IS NOW OVER...BUT NOT BEFORE 3 DAY TOTALS OF 2.5 TO 3 INCHES OVER PARTS OF NORTHEAST IA/WESTERN WI. AS EXPECTED...THIS LONG PERIOD OF LIGHT TO MODERATE RAIN RESULTING IN GOOD RISES FOR AREA CREEKS AND RIVERS. A FEW LOCATIONS HAVE REACHED BANKFULL OR MINOR FLOOD STAGE. UPPER HALF OF THE KICKAPOO BASIN HAS PAST CREST...WITH THE FLOOD WATERS NOW MOVING DOWN STREAM. AT THIS POINT LOOKING LIKE CREST WILL BE JUST BELOW FLOOD STAGE. SAME FOR THE UPPER IOWA RIVER...WITH DORCHESTER THE CLOSEST TO REACHING BANKFULL. MOST SIGNIFICANT RISES WERE ALONG THE TURKEY RIVER...ESPECIALLY FROM ELKADER DOWN THROUGH GARBER. MINOR IN THAT AREA...CRESTING NEAR OR JUST ABOVE FLOOD STAGE. THE BLACK RIVER APPEARS TO BE HAVING THE WORST OF IT...HAVING JUST COME DOWN FROM A SIGNIFICANT RISE LAST WEEK. ANTECEDENT CONDITIONS AND NEW RAIN TOTALS SENDING HATFIELD AND BLACK RIVER FALLS TO THE HIGHEST CRESTS IN A WHILE. THIS WILL TRANSLATE DOWNSTREAM TOWARD GALESVILLE. EXPECT HIGHWAY VV TO BE CLOSED AGAIN ALONG THE LA CROSSE/TREMPEALEAU COUNTY LINE FOR THE NEXT SEVERAL DAYS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM......THOMPSON AVIATION/HYDROLOGY...MW wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 329 AM EDT SUN APR 20 2008 .SHORT TERM...TODAY THE CENTER OF THE UPPER LEVEL CIRCULATION/LARGE CUTOFF LOW OVER EASTERN KENTUCKY EARLY THIS MORNING WILL CONTINUE TO SLOWLY TRACK OFF TO THE SOUTHEAST TODAY...AWAY FROM SOUTHERN LOWER MICHIGAN. THIS WILL RESULT IN SOME MID LEVEL WARMING/500 MB HEIGHT RISES...AS 500 MB TEMP IS FORECASTED TO RISE TO -15 C THIS AFTERNOON...UP FROM THE -19 C WHICH THE 00Z DTX RAOB INDICATED. MEANWHILE...DEEP EASTERLY FLOW IN THE LOW LEVELS WILL LEAD TO MODEST COLD AIR ADVECTION DURING THE DAY...AS 850 MB TEMPS FORECASTED TO DROP TO 8 TO 10 C BY 00Z MONDAY. WITH THE MID LEVEL WARMING AND LIMITED MOISTURE...THINKING SHOWERS ARE GOING TO BE HARD TO COME BY...AND CERTAINLY DON`T EXPECT ANY THUNDERSTORMS WITH LESS INSTABILITY TODAY. BASED ON THE BEST LOW LEVEL CONVERGENCE/MOISTURE POOLING...THINKING THE BEST CHANCE FOR SHOWERS WILL BE ACROSS LENAWEE/WASHTENAW COUNTIES. BUT EVEN THERE...DON`T SEE MUCH MORE THAN LOW CHANCE POPS. WITH RELATIVELY STABLE MARINE LAYER PUSH...PLANNING TO GO DRY/SLIGHT CHANCE POPS FOR THUMB REGION/NORTH HALF OF THE CWA. AS FAR AS TEMPERATURES GO...AFTER SUCCESSFULLY CHOOSING THE WARMER NAM TEMPS YESTERDAY...WILL CONTINUE TO TO LEAN TOWARD WARMER MAXES AS THERE SHOULD BE CONSIDERABLE INSOLATION...OFFSET BY THE PREVIOUSLY MENTIONED LOW LEVEL COLD ADVECTION AND MARINE LAYER. WITH THOSE CONSIDERATIONS...FORESEE MAXES PREDOMINATELY AROUND 70/LOWER 70S...EXCEPT MID 70S IN AND AROUND THE FLINT VICINITY. INTERESTING TO NOTE...TODAY WILL MARK THE 4TH CONSECUTIVE DAY FLINT`S MAX WILL EXCEED 70 DEGREES. THE AVERAGE NUMBER OF OCCURRENCES (MAX GREATER THAN 70 DEGREES) FOR THE MONTH OF APRIL IS 4...WITH THE RECORD BEING 11 DAYS (1977/1985). A LOOK AT THE FORECAST OVER THE NEXT COUPLE OF DAYS SHOWS SHOWS MAXES CONTINUING TO RISE ABOVE 70. SO...ALTHOUGH SOME MAY HAVE COMPLAINED SPRING ARRIVED A BIT LATE...WE CERTAINLY HAVE TURNED THINGS AROUND. && .LONG TERM...TONIGHT THROUGH SATURDAY AS UPPER LOW DRIFTS INTO THE MID ATLANTIC REGION... PRECIPITATION THREAT FOR SOUTHEAST MICHIGAN WILL DIMINISH TONIGHT AND CONTINUE THROUGH TUESDAY. GFS STILL HAS A LITTLE BIT OF CAPE EVIDENT OVER SOUTHWEST LOWER MONDAY AFTERNOON AND PARAMETERIZATIONS IMMEDIATELY KICK OFF A LARGE AREA OF QPF. OBVIOUSLY THINK THIS IS OVERDONE AND WILL KEEP MONDAY AFTERNOON DRY ACROSS THE AREA. MODELS ARE PRETTY CONSISTENT WITH TIMING OF NEXT FRONT INTO THE WESTERN GREAT LAKES ON TUESDAY ALTHOUGH GFS IS SLIGHTLY FASTER THAN THE NAM... BUT PRETTY CONSISTENT WITH PREVIOUS CYCLES. IN EITHER CASE... WILL KEEP CHANCE-TYPE POPS GOING TUESDAY NIGHT AND EARLY WEDNESDAY AS THE FRONT MOVES THROUGH. A LOT OF UNCERTAINLY REMAINS IN THE LATTER STAGES OF THE FORECAST. THE LAST THREE GFS CYCLES ARE ALL STICKING WITH A SIGNIFICANT SYSTEM MOVING INTO THE UPPER MIDWEST AND ONTARIO... BUT HAVE JUMPED THE MAIN SURFACE VALID 18UTC FRIDAY FROM UPPER MICHIGAN TO NEAR JAMES BAY AND NOW TO NORTHERN MINNESOTA. APPROACH OF SURFACE FRONT DURING THIS TIMEFRAME CERTAINLY SUPPRTIVE OF POPS FOR FRIDAY INTO SATURDAY... ALTHOUGH EXTENT OF PRECIPITATION IS STILL A LITTLE UP IN THE AIR. IF LATEST GFS CYCLE VERIFIES... EXPECT SIGNIFICANT NEGATIVE TILT TO UPPER TROUGH IN THE PLAINS BY FRIDAY WITH A CHANCE OF SEVERE WEATHER - DESPITE MINIMAL PRE-FRONTAL INSTABILITY INDICATED ALONG AND AHEAD OF THE FRONT. && .MARINE... MAIN STORY FROM A MARINE STANDPOINT IS STABLE CONDITIONS OVER WATER PERSISTING THROUGH THE WEEK. EVEN WITH A FRONTAL PASSAGE ON TUESDAY NIGHT TO EARLY WEDNESDAY TIMEFRAME... NOT ENOUGH COLD ADVECTION EXPECTED TO REALLY MIX HIGHER MOMENTUM TO THE SURFACE. ADDITIONALLY... DON`T EXPECT SURFACE PRESSURE GRADIENT TO REALLY TIGHTEN UP ENOUGH TO OVERCOME STABILITY CONCERNS... AHEAD OF OR BEHIND THR FRONT. BOTTOM LINE... EXPECTING A HARD TIME ACHIEVING EVEN SMALL CRAFT WIND CONDITIONS THIS WEEK ANYWHERE OVER LAKE HURON AND LAKE ST. CLAIR. && .PREV DISCUSSION...ISSUED 100 AM EDT SUN APR 20 2008 / AVIATION... LOWER LEVELS CONTINUE TO REMAIN RATHER DRY. THE 00Z NAM AND RUC SEEM TO HAVE A REASONABLE HANDLE ON THIS LOW LEVEL DRY AIR BASED OFF THE 00Z DTX SOUNDING. BOTH NAM AND RUC SUGGEST CEILINGS WILL REMAIN VFR THROUGH THE DAY...WHICH LOOKS REASONABLE GIVEN UPSTREAM CEILING HEIGHTS ON THE NORTHERN FRINGE OF THE DEEPER MOISTURE ASSOCIATED WITH THE UPPER LOW NOW OVER KENTUCKY. A WEAK AREA OF SURFACE LOW PRESSURE EXTENDING ACROSS SOUTHERN MICHIGAN AND SOUTHERN ONTARIO IS FORECAST TO SLOWLY BUILD TO THE WEST DURING THE COURSE OF THE DAY. DESPITE THE DRY LOWER LEVELS...SOME SHALLOW FOG POTENTIAL STILL LOOKS POSSIBLE DURING THE 08Z AND 14Z TIME FRAME GIVEN THE WEAK SURFACE CONVERGENCE AND UPPER 40 TO LOWER 50 SURFACE DEWPOINTS IN THE AREA. WITH SIGNIFICANT BREAKS IN THE MID CLOUDS AROUND FNT AND MBS...HAVE LOWERED VISIBILITIES TO AROUND 1 MILE BY DAYBREAK. MEANWHILE...WILL RAISE FORECAST VISIBILITIES AROUND DTW SLIGHTLY GIVEN THE MORE EXTENSIVE MID CLOUD DECK. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...SF LONG TERM....05 MARINE.......05 AVIATION.....SC YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 130 AM EDT SUN APR 20 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .SYNOPSIS (ISSUED AT 350 PM EDT)... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF ALG THE W COAST AND BLDG RDG OVER THE E HALF OF NAMERICA. CUTOFF LO UNDER THE BLDG RDG IS MOVING E THRU THE OH VALLEY WHILE ANOTHER SHRTWV IS LIFTING INTO WRN LK SUP. INTERACTION OF THIS SHRTWV/ ASSOCIATED UPR DVGC/DPVA/H85-5 QVECTOR CNVGC WITH DEEPER MSTR SHOWN ON THE 12Z MPX RAOB IS CAUSING SCT -SHRA/QUITE A BIT OF LO CLD OVER THE NW HALF OF THE FA EARLY THIS AFTN. BUT 12Z GRB/APX RAOBS SHOW MUCH DRIER AIR IS PRESENT TO THE SE ABV LINGERING SHALLOW MSTR. WITH SE H85 WINDS BTWN CUTOFF LO IN THE OH VALLEY AND HUDSON BAY HI PRES...THIS DRY IS OVERSPRDG THE FA...HAS ENDED THE PCPN OVER THE SCNTRL AND E...AND IS TENDING TO DIMINISH THE SHRA COVG OVER THE NW. && .SHORT TERM (TONIGHT AND SUNDAY ISSUED AT 350 PM EDT)... FOR TNGT...GENERAL MSLP/UPR HGT RISES FCST OVER THE UPR LKS DOWNSTREAM OF DEEPENING TROF IN THE W. WITH PERSISTENT ELY FLOW BTWN HUDSON BAY HI AND DEPARTING CLOSED LO IN THE OH VALLEY...EXPECT DRIER AIR IN THAT DIRECTION TO CONTINUE MAKING INROADS ESE-WNW THRU THE FA. WL RESTRICT MENTION OF POPS THIS EVNG TO THE W BEFORE DROPPING MENTION OF PCPN EXCEPT OVER WRN LK SUP UNDER LINGERING DEEPER MSTR CLOSER TO INCRSGLY SHEARED SHRTWV IMPACTING THAT AREA. EVEN THOUGH THE MID LVLS WL BE DRYING OUT...SUSPECT THE LLVL MSTR WL BE HARDER TO DISLODGE. THIS LLVL MSTR WL BE MOST RESILIENT OVER THE NW IN AREAS WHERE LO CLDS HAVE LINGERED THRU THE DAY AND LIMITED INSOLATION/MIXING. SO WL FCST AREAS OF FOG TO DVLP DESPITE SOME LINGERING HI CLD. HOWEVER...CONDITIONS DON`T APPEAR IDEAL FOR DENSE FOG FORMATION WITH FCST RELATIVELY SHARP PRES GRADIENT BTWN HI TO THE N AND LO IN THE OH VALLEY. EXPECT ONLY PTCHY FOG OVER THE E CONSIDERING THE DEEPER MIXING EVIDENT THERE THIS AFTN. WL TEND TO UNDERCUT MOS FCST LO TEMPS OVER THE INTERIOR E CLOSER TO THE CORE OF THE DRIEST AIR. ON SUN...ACYC ENE FLOW WL DOMINATE THE UPR GRT LKS. WITH DRY AIR ABV THE SFC IN THE MRNG...INSOLATION SHOULD MIX OUT RADIATION FOG. BUT NE FLOW OFF LK SUP MIGHT TEND TO KEEP THE FOG/LO CLD MORE RESILIENT NEAR THE SHORE. DEEP MIXING TO H75 ON GFS FCST SDNGS (NAM/GFS BOTH SHOW H85 TEMPS ARND 10C) WOULD SUPPORT HI TEMPS APRCHG 70 AWAY FM LK MODERATION AS OBSVD IN NRN LWR MI THIS AFTN. BUT TEMPS NEAR LK SUP/ THE GREEN BAY SHOULD BE QUITE A BIT COOLER. SINCE GFS/NAM GENERATE SOME LGT QPF OVER NRN WI BTWN 18Z-24Z...CHECKED FOR THE POTENTIAL FOR SOME INSTABILITY SHRA. BUT EVEN FOR HI TEMPS REACHING AOA 70... UNABLE TO GET ANY SUBSTANTIVE CAPE WITH LLVLS DRIED BY MIXING AND WRMG MID LVLS UNDER UPR RDG. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... THE 500MB RIDGE LOOKS TO REMAIN IN PLACE OVER THE CWA UNTIL SUNDAY NIGHT. AT THAT TIME...SOUTHWESTERLY FLOW WILL BEGIN AS THE TROUGH OVER THE PACIFIC NORTHWEST SLOWLY EDGES EASTWARD TOWARDS THE GREAT LAKES REGION. CAN UNDERSTAND WHY THE TREND HAS CONTINUED...SLOWING THE ONSET OF PRECIPITATION DOWN MONDAY NIGHT AND TUESDAY. IN FACT...IT LOOKS MORE LIKE TUESDAY AFTERNOON BEFORE ANY SIGNIFICANT PRECIPITATION HITS THE WESTERN CWA. HPC GUIDANCE BACKS THIS SCENARIO UP. HOWEVER...THE 12Z RUNS OF THE NAM AND GFS HAVE QUICKENED THINGS UP ROUGHLY 6 HOURS FROM THEIR PREVIOUS RUNS. COMPARED TO THE OTHER OPTIONS...THE GFS WAS QUICKER. CAN NOT IGNORE THIS TREND...AND HAVE MADE SMALL ADJUSTMENTS WHILE ATTEMPTING TO NOT JUMP AROUND TOO MUCH DURING THIS PERIOD. THE PACIFIC TROUGH LOOKS TO SHIFT NE INSTEAD OF STRAIGHT EAST...RESULTING IN A MORE NORTHERLY BROAD SCALE TROUGH FOR US TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON. STILL...CONTINUE TO LOOK FOR THE POTENTIAL FOR HEAVY RAIN AND THUNDERSTORMS AHEAD AND ALONG THE COLD FRONT AS IT SLIDES ACROSS. A HIGH PRESSURE RIDGE IS THEN FIGURED WEDNESDAY NIGHT THROUGH THE DAYTIME HOURS THURSDAY. THEN AGAIN...ANOTHER PACIFIC TROUGH SHOULD EDGE OVER THE WESTERN STATES TO NE MN/SOUTHERN ONTARIO BY 12Z SATURDAY. THE GFS IS THEN MUCH MORE PROGRESSIVE...TRYING TO DIVE THE TROUGH OVER THE SOUTHERN LAKES WHILE OTHER MODELS SEEM TO CONTINUE WITH A GENERAL E TO NE TRACK. FROM FRIDAY ON THE FORECAST BECOMES A BUGABOO. WITH MODEL VARIABILITY PRETTY HIGH...AND FORECAST CONFIDENCE RUNNING LOW AT THIS TIME FRAME...WILL OPT TO UTILIZED HPC GUIDANCE HEAVILY. THIS GENERALLY MEANT FOLLOWING A 00Z ECMWF FORECAST...WITH A BLEND OF ITS ENSEMBLE MEAN. && .HYDROLOGY... LOCATIONS THAT RECEIVED THE LEAST RAINFALL OVER THE LAST 36 HOURS...IN SOUTHERN AND EASTERN UPPER MICHIGAN...WERE ALSO THE LOCATIONS WITH THE SMALLEST SNOWMELT CONCERNS. LOCATIONS TO THE NORTH AND WEST RECEIVED BETWEEN A QUARTER TO A HALF INCH OF RAINFALL...ADDING TO SNOWMELT GOING INTO ALREADY HIGH RIVERS. HIGHS IN THE 40S SATURDAY...AND NEAR 60 ON SUNDAY AND MONDAY WILL RESULT IN RIVER LEVELS CONTINUING TO RISE. EVENING OBS ARE INLINE WITH FORECASTS FROM THE RIVER FORECAST CENTER...SO NO NOTABLE CHANGES HAVE BEEN MADE TO ONGOING STATEMENTS. LOCATIONS WITH THE HIGHEST CONCERN REMAIN THE CHOCOLAY RIVER NEAR HARVEY...AND THE STURGEON RIVER NEAR CHASSELL. FOR CONTINUED UPDATES ON THE RIVERS... PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 06Z TAF ISSUANCE)... FCST REMAINS CHALLENGING AT KSAW AND KCMX. SOMEWHAT DRIER AIR MANAGED TO SLIP INTO KSAW EARLY IN THE EVENING...RESULTING IN CIGS RISING TO VFR. CHECK OF KMQT VAD WIND PROFILE SHOWS LOW-LEVEL WINDS JUST OFF THE SFC HAVE VEERED MORE ERLY THAN EXPECTED...ALLOWING FOR MORE SUBSTANTIAL LOW-LEVEL DRYING. HOWEVER...NOT CONVINCED CIGS WILL REMAIN VFR THRU THE NIGHT. SINCE UPSTREAM SFC DWPTS ARE STILL SIMILAR TO CURRENT TEMP AT KSAW...UPSLOPING WINDS MAY STILL RESULT IN LOW CIGS (LIFR) DEVELOPING. LOOKS LIKE THERE WILL BE SUFFICIENT WIND TO KEEP VIS FROM FALLING ANY LOWER THAN MVFR IF FOG DEVELOPS. EXPECT CONDITIONS TO IMPROVE TO VFR EARLY IN THE AFTN. AT KCMX...A LITTLE MORE CONFIDENT THAT LIFR/IFR CIGS WILL PERSIST THRU THE NIGHT. THERE STILL APPEARS TO BE POTENTIAL FOR VIS TO DROP TO LIFR IN FOG GIVEN LIGHTER WINDS AND RECENT RAINFALL EARLIER IN THE NIGHT. EXPECT CONDITIONS TO IMPROVE TO VFR EARLY IN THE AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE FROM JAMES BAY INTO QUEBEC TO REMAIN NEARLY STATIONARY THROUGH SUNDAY. MEANWHILE...LOW PRESSURE OVER SOUTHERN LAKE MICHIGAN IS EXPECTED TO DISSIPATE OVER THE SOUTHERN GREAT LAKES BY LATE SUNDAY. ALSO ON SUNDAY...LOW PRESSURE WILL DEVELOP OVER THE NORTHERN ROCKIES...THEN LIFT NORTHEAST TO HUDSON BAY BY TUESDAY EVENING AND DRAG A TROUGH OF LOW PRESSURE ACROSS THE WESTERN GREAT LAKES BY TUESDAY NIGHT. BEHIND THIS TROUGH...HIGH PRESSURE WILL SLIDE SOUTHEAST ACROSS THE GREAT LAKES REGION ON WEDNESDAY. A LOW PRESSURE SYSTEM DEVELOPING OVER THE CENTRAL PLAINS WILL THEN APPROACH THE WESTERN GREAT LAKES REGION ON THURSDAY. FOR THE MOST PART...WINDS SHOULD REMAIN UNDER 20 KTS INTO TUESDAY. EXPECT STRONGER SOUTH WINDS OVER THE EAST IN THE ADVANCE OF THE APPROACHING TROUGH ON TUESDAY/TUESDAY NIGHT. STRONGER WEST TO NORTHWEST WINDS WILL ARRIVE FOLLOWING THE PASSAGE OF THE TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...KC LONG TERM...KF HYDROLOGY...TG/KC/ROLFSON AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 120 AM EDT SUN APR 20 2008 .AVIATION...VFR CONDITIONS THRU THE FORECAST. AN UPPER LEVEL LOW PROGRESSING THRU THE OHIO VALLEY WILL CONTINUE TO SEND MID AND HIGH CLOUDS OUR WAY THRU THE PRE-DAWN HOURS...BUT THESE WILL DIMINISH DURING THE UPCOMING DAY. LIGHT NORTHEAST WINDS WILL PREVAIL...WITH LAKE BREEZES DURING WINDS ONSHORE BY MIDDAY. JZ && .UPDATE...ISSUED 920 PM SAT APR 19... UPPER LOW SPINNING AWAY IN THE OHIO VALLEY...WITH A LESS WELL-DEFINED SURFACE LOW IN THE SOUTHERN LAKES. WE REMAIN TOO FAR NORTH TO HAVE MUCH OF A PRECIP THREAT. EARLIER (ABOUT 530PM)...THE LAKE MI LAKE BREEZE COLLIDED WITH A WELL-DEFINED HORIZONTAL ROLL... SPITTING OUT A SINGLE SHOWER THAT BROUGHT SOME RAINDROPS TO ACME AND MAPLETON. A MORE SUBSTANTIAL AREA OF SHOWERS BLOSSOMED IN W CENTRAL LOWER JUST AFTER THAT...WHERE SURFACE DEW POINTS WERE IN THE 40S (VS THE 30S UP HERE). THESE SHOWERS GRAZED THE MBL AREA. OTHERWISE...MID AND HIGH CLOUDS AND HAZY SKIES ARE THE RULE. GRIDS WERE UPDATED FOR AN ISOLATED SHOWER OR TWO IN THE SW ZONES THRU 02Z/10PM. WITH LOSS OF HEATING...THE REST OF THE NIGHT WILL BE DRY. WILL LOWER MIN TEMPS AT SOME COASTAL LOCATIONS...WHERE LAKE BREEZES HAVE GIVEN THEM A HEAD START IN COOLING OFF. ZOLTOWSKI && .PREV DISCUSSION...ISSUED 303 PM SAT APR 19... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LEVEL LOW SPINNING OVER THE SOUTHERN IL-IN BORDER AND A BROAD AREA OF SURFACE LOW PRESSURE OVER THE SOUTHERN GREAT LAKES. BANDS OF MID AND UPPER LEVEL CLOUD COVER CONTINUE TO ROTATE ACROSS NORTHERN MICHIGAN WITH HOLES IN THE CIRRUS SHIELD APPEARING EVERY NOW AND THEN. THESE CLOUDS HAVE NOT PREVENTED TEMPERATURES FROM RAPIDLY WARMING INTO THE LOW TO MID 70S INLAND. WITH PRECIP WELL TO THE SOUTH OVER FAR SOUTHERN LOWER MICHIGAN...MAIN FORECAST CONCERNS INCLUDE TEMPS AND SKY COVER TONIGHT...THEN SMALL CHANCES OF PRECIP ALONG LAKE BREEZE BOUNDARIES TOMORROW. TONIGHT...UPPER LOW WILL DRIFT SLIGHTLY SOUTH OF EAST AS IT CUTS ACROSS THE OHIO RIVER VALLEY TO THE CENTRAL APPALACHIANS. SPOKE OF UPPER LEVEL MOISTURE WILL PINWHEEL ACROSS NORTHERN MICHIGAN TONIGHT...BUT FORCING AND DEEP MOISTURE WILL REMAIN WELL SOUTH OF THE REGION. THAT LEAVES TEMPERATURES AND SKY COVER TO THINK ABOUT. LOWS LAST NIGHT DIPPED INTO THE MIDDLE AND UPPER 30S ACROSS NE LOWER WHERE CLEAR SKIES HUNG ON THE LONGEST. DO NOT THINK THAT WILL HAPPEN TONIGHT DUE TO THE CIRRUS SHIELD...EVEN THOUGH THIS CIRRUS WILL THIN OVERNIGHT ACROSS NORTHERN LOWER. SO HAVE KEPT LOWS SIMILAR TO LAST NIGHT EXCEPT RAISED THEM A FEW DEGREES OVER NE LOWER. LOWS IN THE 40S. TOMORROW...UPPER LOW WILL MEANDER ACROSS THE CENTRAL APPALACHIANS WHILE MID-LEVEL HEIGHTS SLOWLY BUILD ACROSS THE NORTHERN GREAT LAKES. NO LARGE-SCALE FORCING TO SPEAK UP WITH THE BUILDING RIDGE...BUT STILL HINTS THAT LOCALIZED CONVERGENCE WILL SETUP ACROSS THE SW CWA WITH PREVAILING EAST FLOW BUTTING HEADS AGAINST LAKE BREEZES OFF OF LAKE MICHIGAN AND GRAND TRAVERSE BAY. BOTH NAM/GFS SPIT OUT QPF CENTERED AROUND WEXFORD COUNTY...BUT THINK THIS IS MORE OF A BY-PRODUCT OF OVER-GENEROUS SURFACE DEWPOINTS...WHICH BOTH MODELS SHOW IN THE LOWER TO MID 50S. DEEP MIXING UP TO 775MB SUGGESTS DEWPOINTS WILL MIX OUT TO AROUND 48F. USING A TEMP OF 72F...THIS WOULD YIELD SKINNY ML CAPES AROUND 200 J/KG IN THE MORE MOIST NAM SOLUTION...WHILE THE DRIER GFS SUGGESTS TOO MUCH CIN WILL EXIST TO TRIGGER A SHOWER. GIVEN THE INCREASING SUBSIDENCE THROUGH THE DAY...LEAN MORE TOWARD THE DRIER SOLUTION AND WILL LEAVE POPS OUT OF THE FORECAST. ANOTHER WARM DAY ON TAP WITH HIGHS RANGING FROM THE MID 60S NORTH/NEAR LAKESHORES...TO THE LOWER 70S INLAND. MPC SUN NIGHT THRU MON NIGHT...RATHER QUIET PERIOD OF WX EXPECTED TO CONTINUE...THOUGH A FEW FCST CONCERNS REMAIN...NAMELY TEMPS MON AFTN ALONG WITH ANY SMALL PRECIP CHANCES THRU THE PERIOD. POTENT CLOSED LOW SPINNING OVR SOUTHERN IN THIS AFTN PROGGED TO SLIP INTO VIRGINIA BY EARLY MON...WITH BROAD SHORTWAVE RIDGING BUILDING ACRS THE LAKES IN ADVANCE OF NEXT UPSTREAM TROUGH OVR THE NORTHWEST. HOWEVER... CONCERN REGARDING POTENTIAL PRECIP STEMS FROM BROAD PLUME OF WRAP AROUND MOISTURE PROGGED TO ADVECT BACK INTO THE REGION SUN NIGHT TIMEFRAME...AS UPR GYRE ABLE TO TAP ADDITIONAL MOISTURE FROM THE ATLANTIC. INTERESTING TO NOTE BOTH NAM AND GFS SPIT OUT A HINT OF MEASURABLE PRECIP SUN NIGHT/EARLY MON THOUGH DIFFICULT TO FORESEE THIS GIVEN OVERALL LACK OF MID/UPR LEVEL MOISTURE AND FORCING...WITH ONLY SOME WEAK HINT OF CHANNELED VORT (REMNANTS OF CLOSED LOW TO THE SOUTH TODAY) HEADING NORTH THRU THE NIGHT. THUS WILL MAINTAIN DRY FCST AT THIS TIME. HEADING INTO MON AFTN...APPEARS ANOTHER WARM DAY ON TAP WITH DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING UPR TROUGH...THOUGH OVERALL LACK OF MIXING PER LOW LEVEL RIDGE AXIS DRAPED OVERHEAD SHOULD KNOCK A FEW DEGREE OFF POTENTIAL HIGHS (READINGS MAINLY MID/UPR 60S LOOK GOOD). DESPITE GOOD HEATING AND LIKELY LAKE BREEZE CONVERGENCE ALONG THE LAKE MICHIGAN SIDE... DIFFICULT TO SEE CONVECTION (OTHER THAN A FAIRLY HEALTHY CU FIELD) FIRING DESPITE AN INCREASE IN BOUNDARY LAYER MOISTURE...AS MID LEVEL SUBSIDENCE INVERSION BUILDS THRU THE DAY. LATER PERIODS (TUE THRU SAT)...PATTERN TO REMAIN QUITE BLOCKY THRU THE EXTENDED PORTION OF THE FCST...OWING TO HIGHLY AMPLIFIED/ CLOSED MID LEVEL RIDGE ACRS CENTRAL/EASTERN ALASKA...IMPLYING SIGNIFICANT DOWNSTREAM TROUGHING INTO THE WESTERN CONUS. INDEED... THIS TYPE OF PATTERN IS WHAT THE MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST...WITH INITIAL CLOSED LOW (EVIDENT THIS AFTN NEAR THE BRITISH COLUMBIA/WASHINGTON STATE BORDER) AND ASSOCIATED ENERGY SHEARING OUT INTO THE NORTHERN PLAINS/UPR MIDWEST ON TUE...OWING TO BRIEF DISRUPTION OF BLOCKING FLOW ACRS THE EASTERN PACIFIC AS ENERGY UNDERCUTS THE RIDGE. END RESULT FOR NORTHERN MI WILL BE INCREASING CHANCES FOR PRECIP TUE NIGHT AS ASSOCIATED SFC FRONT AND WEAKENING FORCING SLIDES THRU THE REGION. WILL CONTINUE THUNDER MENTION AS WELL WITH EXPECTED DECENT MOISTURE TAP INTO THE AREA VIA OPEN GULF...AND MODEL PROGS OF SHOWALTER INDICES DIPPING WELL BELOW 0C ALONG WITH STEEPER MID LEVEL LAPSE RATE PLUME OVERHEAD. PONDERED BRINGING SMALL POPS BACK INTO THE PICTURE FOR TUE AFTN AS MOISTURE INCREASES AHEAD OF THE FRONT...WITH POTENTIAL FOR BRIEF CONVECTION TO POP AHEAD OF THE BOUNDARY GIVEN EXPECTED HEATING AND LIKELY LOW LEVEL WEAK UPSLOPE REGIME INTO THE HIGHER TERRAIN PER BACKING OF FLOW AHEAD OF THE FRONT...THOUGH ANYTHING ISOLATED AT BEST SO DRY FCST WILL CONTINUE. TEMPS TUE IFFY PENDING DEGREE OF SUN...THOUGH POTENTIAL IS THERE FOR A VERY WARM DAY WITH REGION IN THE THERMAL RIDGE AHEAD OF THE FRONT. WILL RUN WITH MID 60S TO LOWER 70S AREAWIDE. STILL LOOKS LIKE A DRY AND MORE SEASONABLE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGING AND ASSOCIATED SUBSIDENCE/DRYING TAKE HOLD. 00Z GUIDANCE NUMBERS APPEAR A BIT TOO COOL GIVEN EXPECTED SUN...SO WILL RUN WITH TEMPS UPR 50S TO MID 60S. THEREAFTER...GUIDANCE BEGINS TO DIVERGE ON AMPLITUDE OF ADDITIONAL WESTERN TROUGHING THU/FRI...THOUGH PATTERN RECOGNITION WITH DEEP LAYER/MERIDIONAL RIDGE BECOMING RE-ESTABLISHED ACRS ALASKA CERTAINLY ARGUES FOR THE ECMWF/GEFS MEAN SOLUTIONS OF A DEEPER WESTERN TROUGH. REGARDLESS OF EVENTUAL SOLUTION...IMPLICATION FOR THE CWA IS ADDITIONAL PRECIP CHANCES FRI/SAT TIMEFRAME AS LEE CYCLOGENESIS GETS GOING ON THE PLAINS...WITH ASSOCIATED COLD FRONT HEADING EAST BY THE WEEKEND. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 100 AM EDT SUN APR 20 2008 .AVIATION... LOWER LEVELS CONTINUE TO REMAIN RATHER DRY. THE 00Z NAM AND RUC SEEM TO HAVE A REASONABLE HANDLE ON THIS LOW LEVEL DRY AIR BASED OFF THE 00Z DTX SOUNDING. BOTH NAM AND RUC SUGGEST CEILINGS WILL REMAIN VFR THROUGH THE DAY...WHICH LOOKS REASONABLE GIVEN UPSTREAM CEILING HEIGHTS ON THE NORTHERN FRINGE OF THE DEEPER MOISTURE ASSOCIATED WITH THE UPPER LOW NOW OVER KENTUCKY. A WEAK AREA OF SURFACE LOW PRESSURE EXTENDING ACROSS SOUTHERN MICHIGAN AND SOUTHERN ONTARIO IS FORECAST TO SLOWLY BUILD TO THE WEST DURING THE COURSE OF THE DAY. DESPITE THE DRY LOWER LEVELS...SOME SHALLOW FOG POTENTIAL STILL LOOKS POSSIBLE DURING THE 08Z AND 14Z TIME FRAME GIVEN THE WEAK SURFACE CONVERGENCE AND UPPER 40 TO LOWER 50 SURFACE DEWPOINTS IN THE AREA. WITH SIGNIFICANT BREAKS IN THE MID CLOUDS AROUND FNT AND MBS...HAVE LOWERED VISIBILITIES TO AROUND 1 MILE BY DAYBREAK. MEANWHILE...WILL RAISE FORECAST VISIBILITIES AROUND DTW SLIGHTLY GIVEN THE MORE EXTENSIVE MID CLOUD DECK. && .PREV DISCUSSION...ISSUED 1000 PM EDT SAT APR 19 2008 UPDATE... UPSTREAM RADAR IMAGERY SUGGESTS BULK OF RAIN SHOWERS WILL REMAIN JUST SOUTH OF THE STATE LINE...WITH SCATTERED ACTIVITY IMPACTING ROUGHLY THE M 59 CORRIDOR SOUTHWARD. WILL UPDATE THE GRIDS/ZONES TO ACCOUNT FOR THESE LATEST TRENDS AND TO LOWER POPS ALONG AND NORTH OF THE I 69 CORRIDOR. THE BETTER CHANCES FOR PRECIP FARTHER NORTH SHOULD HOLD OFF UNTIL LATE TONIGHT WHEN SOME MID LEVEL DEFORMATION ASSOCIATED WITH THE OHIO VALLEY UPPER LOW BEGINS TO MOVE IN FROM THE EAST. DEWPOINTS HOLDING IN THE MID 40S TO LOWER 50S ALONG WITH A LINGERING SURFACE TROUGH OVER SOUTHERN MICHIGAN WILL CONTINUE TO SUPPORT AREAS OF FOG LATE TONIGHT. SOME CLEAR SKIES TO THE NORTH WILL ALSO HELP IN RADIATIONAL COOLING. THE ONLY OTHER UPDATE TO THE FORECAST WILL BE TO LOWER TEMPS A COUPLE DEGREES AROUND THE TRI CITIES WHERE TEMPS ARE ALREADY IN THE LOWER 50S THANKS TO THE MARINE LAYER THAT HAD ADVECTED INLAND OFF SAGINAW BAY. PREV DISCUSSION...ISSUED 330 PM EDT SAT APR 19 2008 SHORT TERM...TONIGHT THE BEST CHANCE OF RAIN TONIGHT WILL BE NEAR THE OHIO BORDER BUT CLOUDS AND MILD TEMPERATURES WILL AFFECT ALL OF SE MICHIGAN TONIGHT. RADAR COMPOSITES INDICATE PRECIPITATION HAS TAKEN ON MORE IMPRESSIVE AREAL COVERAGE OVER SOUTHERN/WESTERN OHIO THIS AFTERNOON. THIS IS WHERE A RESPECTABLE COMBINATION OF FORCING IS COMING TOGETHER ON THE EAST FLANK OF THE UPPER LOW. SATELLITE AND MODEL FIELDS INDICATE THE UPPER LOW IS DOING A GOOD JOB OF BENDING THE LOW TO MID LEVEL THETA-E RIDGE AND APPLYING SOME MODEST DYNAMIC FORCING TO THE MOISTURE TRANSPORT. THIS IS COMBINED WITH SOME COOLER TEMPERATURES ALOFT AND SOME POCKETS OF DAYTIME HEATING GENERATING ENOUGH INSTABILITY FOR ADDED SHOWER COVERAGE ALONG WITH A FEW THUNDERSTORMS. NOW THAT IT IS UNDERWAY, THE PERSISTENCE OF INSTABILITY INTO THIS EVENING WILL KEEP THE SHOWERS/STORMS GOING AS THEY ROTATE TOWARD THE OHIO BORDER REGION OF SE MICHIGAN. THIS WILL OCCUR AS THE ENTIRE LOW PRESSURE SYSTEM SLIDES EASTWARD AND SOUTH OF THE OHIO RIVER. THE SLIGHTLY SE TRACK OF THE SYSTEM WILL KEEP RAIN FROM MOVING VERY FAR NORTHWARD INTO OUR AREA BUT IS STILL WORTHY OF NUMEROUS COVERAGE FOR LENAWEE AND MONROE COUNTIES. LATER ON TONIGHT, EXPECT JUST A GENERAL CHANCE OF LIGHT RAIN SHOWERS IN THE NW PORTION OF THE SYSTEM. THIS WOULD BE DUE TO WEAK MID LEVEL DEFORMATION OVER THE TOP OF THE FILLING SURFACE TROUGH/LOW. MORE IMPORTANT MIGHT BE THE PATCHY FOG EXPECTED TO DEVELOP TOWARD SUNRISE. AS THE SURFACE TROUGH SETTLES INTO LOWER MICHIGAN AND GRADUALLY FILLS/DRIFTS NORTHWEST IT WILL PULL HIGHER DEWPOINT AIR INTO THE REGION WITH SOME POCKETS OF 1 MILE FOG POSSIBLE LATE IN THE NIGHT THROUGH A COUPLE HOURS AFTER SUNRISE SUNDAY MORNING. LONG TERM...SUNDAY THROUGH SATURDAY RESIDUAL TROUGHING WILL PERSIST ON SUNDAY AS THE UPPER LOW DRIFTING ACROSS THE OHIO VALLEY WEAKENS AND TRACKS EAST/SOUTHEAST. WITH MINOR INSTABILITY FROM DAYTIME HEATING...THE CHANCE OF SHOWERS STILL SEEMS REASONABLE AND WILL MAINTAIN THE CURRENT WORDING IN THE FORECAST. DRY WEATHER IS THEN EXPECTED FROM SUNDAY NIGHT INTO TUESDAY AS THIS FEATURE CONTINUE TO DRIFT TO THE EAST COAST...AND UPPER RIDGING AND SURFACE HIGH PRESSURE REMAIN IN PLACE FROM THE GREAT LAKES EAST INTO NEW ENGLAND. DURING THIS TIMEFRAME...A BROAD WESTERN TROUGH WILL BE TAKING SHAPE OVER WESTERN/CENTRAL CANADA INTO THE CONUS. THIS WILL ESTABLISH A MUCH MORE PROGRESSIVE PATTERN OVER THE AREA BY THE MIDDLE OF NEXT WEEK ON INTO NEXT WEEKEND. TIMING INDIVIDUAL DISTURBANCE INTO AND THROUGH THE AREA WILL CONTINUE TO BE AN ISSUE...BUT CONSISTENCY IS SOMEWHAT REASONABLE FOR THE FIRST COLD FRONT...WHICH MOVES THROUGH THE AREA ON TUESDAY NIGHT INTO WEDNESDAY MORNING...AND THE FORECAST IS IN GOOD SHAPE WITH THIS SCENARIO. BY LATE IN THE WEEK...A MORE SUBSTANTIAL STORM SYSTEM APPEARS TO BE DEVELOPING AS A SHORTWAVE IS FORECAST TO DIG SOUTHEAST INTO THE CENTRAL PLAINS WITH A LITTLE MORE AUTHORITY. SUCH A FEATURE SHOULD BE ABLE TAP ADDITIONAL MOISTURE FROM THE SOUTHERN CONUS AND GULF OF MEXICO...LEADING TO SEVERAL DAY PERIOD WITH SHOWERS/THUNDERSTORMS. FIRST...WITH THIS WARM/MOIST SURGE IN ADVANCE OF THE STORM...AND THEN WITH THE STORM CENTER ITSELF. PRECIPITATION WILL BE CARRIED FROM THURSDAY NIGHT INTO THE WEEKEND. TEMPERATURES WILL REMAIN MILD WITH HIGHS IN THE 60S TO AROUND 70 AND LOWS IN THE 40S TO AROUND 50...WHICH IS SLIGHTLY ABOVE NORMAL FOR THIS PART OF APRIL. MARINE... A BROAD AREA OF LOW PRESSURE LOCATED OVER THE SOUTHERN GREAT LAKES TODAY WILL GRADUALLY FILL LATE TONIGHT AND SUNDAY. THIS PROCESS WILL CONFINE THE BEST CHANCE OF RAIN TO LAKE ST CLAIR AND LAKE ERIE TONIGHT, BUT WILL KEEP FAVORABLE WIND AND WAVE CONDITIONS OVER THE ENTIRE REGION THROUGH THE REST OF THE WEEKEND. MODEST SE WINDS WILL THEN PERSIST THROUGH MONDAY AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS IN THE PLAINS. THIS SYSTEM WILL TRACK FROM THE PLAINS ON MONDAY TO THE NORTH OF LAKE SUPERIOR ON TUESDAY AND WILL DRAG A COLD FRONT THROUGH THE REGION DURING THE MID WEEK PERIOD. 30 KNOT WIND SPEEDS WILL BE POSSIBLE OVER THE OPEN WATERS OF LAKE HURON TUESDAY NIGHT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....SC UPDATE.......SC SHORT TERM...BT LONG TERM....DG MARINE.......BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1155 PM CDT SAT APR 19 2008 .PREV DISCUSSION.../ISSUED 350 PM CDT SAT APR 19 2008/ LOW PRESSURE CONTINUES TO DRIFT SLOWLY EASTWARD ACROSS THE LOWER GREAT LAKES. A FEW SHOWERS HAVE DEVELOPED THIS AFTERNOON ACROSS THE WI CWA ALONG A TROF AXIS. HELPING MATTERS IS STRONG HEATING THAT HAS DEVELOPED TO THE EAST AND SOUTH OF KEAU WITH SOME CLEARING. THERMAL GRADIENT ACROSS THE WESTERN HALF OF WI ABOUT 20 DEGREES ATTM. RUC BEST LI INTO THE EVENING AROUND ZERO SO WILL MENTION A FEW SHOWERS AND ISOLATED THUNDER THROUGH THE EVENING. NEXT CONCERN IS FOG POTENTIAL OVERNIGHT. BELIEF IS THAT THE LOW LEVEL FLOW WILL BECOME MORE EASTERLY OVERNIGHT DRAGGING SOME OF THE LOW CLOUDS INTO THE WESTERN CWA WHILE MAINTAINING A GOOD DEAL OF CLOUDINESS ELSEWHERE. DUE TO THE RAINS OVER WI AND SOUTH CENTRAL AREAS OF MN...AREAS OF FOG SHOULD OCCUR AGAIN TONIGHT. HOWEVER..IT COULD BECOME DENSE IF THE LOW CLOUDS WOULD DIMINISH DURING THE NIGHT. THIS LEADS INTO SUNDAY ON HOW HIGH AFTERNOON TEMPERATURES WILL GET IF PARTLY TO MOSTLY CLOUDY SKIES PREVAIL. NAM CU RULE IS QUITE NEGATIVE OVER EASTERN MN AND WEST CENTRAL WI...SO CUT BACK A LITTLE ON THE HIGH TEMPERATURES OVER THE EASTERN HALF OF THE CWA. THINGS REMAIN PRETTY MUCH ON TRACK WITH LOW PRESSURE AND A COLD FRONT APPROACHING WESTERN MN SUNDAY NIGHT AND THEN MOVING TO NEAR THE MN/WI BORDER BY MONDAY NIGHT. MAIN CHANGES TODAY WERE TO TIGHTEN UP ON THE POPS AND KEEP THEM CONFINED TO THE FAR WEST SUNDAY NIGHT WHERE SOME ELEVATED INSTABILITY DEVELOPS AND THEN NOT ALLOW THINGS TO GET TO FAR TO THE EAST TOO FAST ON MONDAY. STILL LOOKS GOOD FOR SHOWERS AND THUNDERSTORMS ALONG THE FRONT...ESPECIALLY EASTERN MN LATE MONDAY AFTERNOON AND EVENING AND THEN SPREADING INTO WI DURING THE NIGHT. THE FRONT BECOMES NEARLY STATIONARY ACROSS WEST CENTRAL WI BY TUESDAY MORNING AS LOW PRESSURE BEGINS TO RIDE NORTHEAST ALONG THE FRONT. PRECIPITATION CHANCES REMAIN HIGH OVER THE EASTERN CWA UNTIL TUESDAY EVENING. CAPE VALUES MODEST ON MONDAY AND LOW LEVEL SHEAR IS DIMINISHING MONDAY AFTERNOON. WHAT IS REALLY INTERESTING IS THE COUPLED JET THAT DEVELOPS ACROSS OUR AREA MONDAY NIGHT AND TUESDAY...GIVING THE EASTERN CWA QUITE A BIT OF DIFFERENTIAL LAYER DIVERGENCE. THIS WILL BE A PERIOD THAT WILL NEED TO BE MONITORED NOT ONLY FOR SEVERE WEATHER BUT HEAVY RAINFALL. A BREAK IN THE RAIN ON WEDNESDAY AS HIGH PRESSURE MOVES BY THEN A MORE VIGOROUS LOW WILL BE MOVING IN FROM THE CENTRAL PLAINS THURSDAY AND FRIDAY WITH SOME PRETTY GOOD APRIL SHOWERS AND THUNDERSTORMS. && .AVIATION.../06Z TAF ISSUANCE/ MAINLY MVFR CIGS IN PLACE UNDER SURFACE RIDGE OVER ALL BUT KAXN. DRIER AIR WAS ADVECTING INTO PARTS OF EAST CENTRAL MN...BUT LO LEVEL FLOW WILL GRADUALLY TURN MORE ESE TOWARD MORNING. EXPECT CEILINGS TO SPREAD NWRD OVER REST OF CWA OVERNIGHT AND SOME LOWERING INTO IFR CATEGORY IS EXPECTED OVER SOUTH CENTRAL MN. AS SE FLOW INCREASES DURING SUNDAY...LOWER CEILINGS WILL CONTINUE TO LIFT INTO CENTRAL AND NW MN WITH CLEARING OVER WEST CENTRAL WISCONSIN AND SOUTH CENTRAL MN. EXPECT VFR CONDITIONS UNDER MAINLY HIGH MAINLY HIGH CLOUDS AFTER 00Z. && .MP WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/JPR mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 418 AM CDT SUN APR 20 2008 .DISCUSSION... SURFACE HIGH PRESSURE CONTINUES TO SLIDE SLOWLY EAST ACROSS CENTRAL PORTIONS OF MISSOURI EARLY THIS MORNING. PESKY STRATUS CLOUDS PERSIST ACROSS NORTH CENTRAL AND NORTHEAST MISSOURI STILL THIS MORNING...BUT SHOULD BE EXITING BY AFTERNOON ALONG WITH THE H8 RIDGE AXIS. THERE HAVE BEEN SOME VARIABLE LOWER VISIBILITIES WITH FOG THIS MORNING...MAINLY IN PROXIMITY TO THE SURFACE RIDGE AXIS WHERE WINDS ARE CALM AND WHERE THE LOW CLOUDS HAVE CLEARED. CONTINUED TO MENTION SOME PATCHY FOG IN THE FORECAST FOR EARLY MORNING...WITH IMPROVEMENT EXPECTED SHORTLY AFTER SUNRISE. TEMPERATURES TODAY WILL WARM RATHER SIGNIFICANTLY...EVEN WITH SOME HIGHER LEVEL CLOUDS SPREADING OVER THE REGION. MIDDLE TO UPPER 70S ARE EXPECTED FOR DAYTIME HIGH TEMPERATURES TODAY...WITH INCREASING SOUTHERLY WINDS DEVELOPING AHEAD OF THE NEXT LOW PRESSURE SYSTEM. THE SOUTHERLY WINDS WILL ALSO START THE RETURN OF INCREASING MOISTURE TO THE REGION THROUGH TOMORROW. THE MOISTURE RETURN WILL SET THE STAGE FOR INCREASED CLOUDS MONDAY...AND EVENTUAL PRECIPITATION CHANCES. KEPT SLIGHT CHANCES FOR SOME POSSIBLE SCATTERED SHOWER AND THUNDERSTORM DEVELOPMENT DURING THE AFTERNOON MONDAY. INSTABILITY WILL BE IN PLACE ALONG WITH WARM ADVECTION/ISENTROPIC LIFT...BUT THE LIMITING FACTOR COULD BE THE FORECAST STRONG CAP. AS A SECONDARY SHORTWAVE TROUGH ROTATES ACROSS THE PLAINS ON THE SOUTHEAST SIDE OF THE SOUTH CENTRAL CANADA UPPER LOW...A SURFACE COLD FRONT WILL BE PUSHED INTO THE FORECAST AREA. THE TIMING OF THE FRONT DIFFERS AMONGST THE MODEL SOLUTIONS. AM EXPECTING THE NORTHERN PORTION OF THE COLD FRONT TO BE PUSHED EAST FASTER ACROSS THE NORTHERN PLAINS WITH THE INITIAL SHORTWAVE...WITH THE SOUTHERN PORTION OF THE FRONT STALLING UNTIL THE SECONDARY SHORTWAVE PUSHES IT EAST. THIS WOULD DELAY THE ARRIVAL OF THE COLD FRONT TO NORTHWEST MISSOURI UNTIL LATE MONDAY NIGHT...WHICH IS WHAT THE GFS SOLUTION HAS BEEN SHOWING. THE CONVERGENCE ALONG THE FRONT MAY BE WHAT IS NEEDED FOR CONVECTION TO BREAK THROUGH THE CAP MONDAY NIGHT INTO EARLY TUESDAY...WHERE THE GRIDDED FORECAST DISPLAYS INCREASED PRECIPITATION CHANCES. STILL CANNOT RULE OUT SOME STRONGER STORMS OVERNIGHT MONDAY INTO EARLY TUESDAY. THE COLD FRONT WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE FORECAST AREA DURING THE DAY TUESDAY....EVENTUALLY PUSHING INTO ARKANSAS. THE FRONT WILL THEN RETURN NORTH AS A WARM FRONT TOWARD THURSDAY...ALONG WITH ANOTHER CHANCE FOR SHOWERS AND STORMS. STOFLET && .AVIATION... FOR THE 06Z TAFS...NAM AND RUC SOUNDINGS DEPICTING THE POTENTIAL FOR FOG DEVELOPMENT BEGINNING IN THE 08-09 UTC TIMEFRAME AT STJ AND PERSISTING THROUGH 13 UTC. BASED ON CLIMATOLOGY...THE DENSEST FOG LIKELY WILL NOT OCCUR UNTIL AROUND SUNRISE...THUS CONTINUED PREVIOUS TAF FORECAST TREND OF INTRODUCING TEMPO GROUP IN THE 10-13 TIMEFRAME. ANY FOG THAT DEVELOPS AT STJ WILL DISSIPATE BY 14-15 UTC DUE TO MIXING. BY LATE MORNING...PRESSURE GRADIENT TIGHTENS SUFFICIENTLY THUS WIND SPEEDS AT ALL THREE TAF SITES WILL INCREASE AT OR ABOVE 12 KNOTS BY 16 UTC. OTHERWISE...VFR CONDITIONS WILL PREVAIL. 24 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 412 AM EDT SUN APR 20 2008 .SYNOPSIS... AN UPPER LEVEL LOW ACROSS THE MIDDLE OHIO VALLEY WILL DRIFT SLOWLY SOUTHEAST TOWARD THE CAROLINA COAST THROUGH TONIGHT. UPPER LEVEL RIDGING WILL BUILD INTO THE REGION BEHIND THIS SYSTEM FOR MONDAY AND TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... WILL USE A BLEND OF THE LATEST RUC MODEL AND OPERATIONAL MODELS FOR THE NEAR TERM FORECAST. AN UPPER LEVEL CLOSED LOW WAS LOCATED OVER ERN KY THIS MORNING. THIS LOW IS FCST TO DRIFT SLOWLY SOUTHEAST TODAY...BEING LOCATED OVER NW NORTH CAROLINA BY THIS EVENING. EMBEDDED VORTICITY LOBES ROTATING AROUND THE LOW...ALONG WITH DAYTIME HEATING/WEAK SFC TO 850 MB CONVERGENCE...WILL RESULT IN A CHANCE FOR SHOWERS ACROSS THE REGION. THE BEST CHANCE IS EXPECTED ACROSS THE SE CWFA. THERE WILL BE ENOUGH INSTABILITY IN THIS AREA TO ALSO WARRANT A MENTION OF THUNDER. TEMPERATURES WILL RANGE FROM THE LOWER TO MID 60S. FOR TONIGHT...ANY SHOWER/THUNDERSTORM ACTIVITY WILL END QUICKLY AFTER SUNSET. SKIES WILL BECOME PARTLY CLOUDY. OVERNIGHT LOWS WILL RANGE FROM THE MID TO UPPER 40S. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... MID LEVEL RIDGING WILL BUILD ACROSS THE OHIO VALLEY AND ERN GREAT LAKES MONDAY THROUGH TUESDAY IN THE WAKE OF THE UPPER LEVEL LOW. THIS PATTERN WILL PROVIDE FOR PARTLY TO MOSTLY SUNNY SKIES DURING THE DAY AND MOSTLY CLEAR CONDITIONS AT NIGHT. HIGHS WILL WARM FROM THE LOWER 70S ON MONDAY TO THE MID AND UPPER 70S ON TUESDAY. FOR TUESDAY NIGHT...A COLD FRONT WILL APPROACH THE REGION FROM THE WEST. HAVE SLOWED THE ONSET OF SHOWERS AND THUNDERSTORMS INTO THE REGION...KEEPING A LOW CHC THREAT LATE TUESDAY NIGHT ACRS THE FAR NW CWFA. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... WEAK COLD FRONT WILL TRAVERSE OH VLY ON WED. PCPN SHOULD REMAIN SCATTERED AT BEST AS MAIN FORCING REMAINS WELL NORTH OF THE REGION ACRS NRN GRT LKS IN CLOSER PROXIMITY TO SFC LO. WEAK LO LVL CONV AND INSTABILITY WILL LIKELY BE MAIN CONTRIBUTORS TO CONVECTIVE DVLPMNT ON WED. CONSIDERED LOWERING POPS A BIT FOR WED BUT HAVE DECIDED TO CONTINUE TO ROLL WITH 40 POPS. SHOULD MODELS CONTINUE TRENDING TOWARDS WEAKER AND MOISTURE-STARVED FRONT FOR WED...LATER SHIFTS WOULD NEED TO CONSIDER LOWERING POPS BACK INTO THE 20-30% RANGE. FRONT WILL DROP SOUTH AND EAST OF THE REGION WED NIGHT AS SFC HI BUILDS IN ACRS THE GRT LKS. MID LVL RIDGE WILL ONCE AGAIN REESTABLISH ACRS EASTERN CONUS ON THURS...BRINGING DRY PLEASANT WX TO THE REGION. WARM FRONT WILL LIFT NORTH THRU THE OH VLY LATE THURS NIGHT AND INTO FRI IN RESPONSE TO SFC LO MOVING INTO THE UPR MISSISSIPPI VLY. 00Z GFS/ECMWF/UKMET AND MAJORITY OF THE GFS ENSEMBLE MEMBERS HAVE ALL COME INTO REASONABLE AGREEMENT IN TRACKING ASSOCD COLD FRONT THRU THE REGION FRI NIGHT INTO SAT AS SFC LO OCCLUDES NORTH OF THE GRT LKS. WILL CARRY CHANCE POPS THRU THIS PERIOD WITH SCT TSTMS POSSIBLE. SFC HI PRES WILL THEN BUILD IN FOR THE SECOND HALF OF THE WEEKEND. WITH MID LVL RIDGE IN PLACE FOR MUCH OF THE SECOND HALF OF THE WORK WEEK...EXPECT ABV NORM TEMPS TO PERSIST WITH AFTN HIGHS IN THE 70S AND LOWS IN THE U40S AND 50S. WITH ZONAL FLO ALOFT IN WAKE OF FROPA ON SAT...EXPECT COOLER AND MORE SEASONABLE TEMPS WITH HIGHS IN THE 60S AND LOWS IN THE 40S. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... UPR LO CENTERED OVER CNTRL KY THIS MRNG WITH SFC LO OVER SRN ONTARIO. MUCH OF THE DEEPER MOISTURE AND LIFT ASSOCD WITH OCCLUDED FRNTL BNDRY HAD PUSHED OFF TO NORTH/EAST OF THE FCST AREA. UPR LO WILL CONTINUE TO MOVE SLOWLY E/SE INTO ERN KY BY DAYBREAK. MID LVL CLOUDS WILL LINGER THRU THE NIGHT WITH POTENTIAL FOR MVFR SC TO ADVECT BACK SOUTH INTO THE NORTHERN TERMINALS AS AFOREMENTIONED SFC LO BEGINS TO SLIP BACK SOUTHEAST. IFR AND LOWER VSBY/CIGS RESTRICTIONS HAVE DVLPD OVER CNTRL OH WHERE MOST RAINFALL OCCURRED ON SAT. EXPECT IFR AND LOWER CONDITIONS TO PERSIST THRU DAYBREAK AT KCMH/KLCK. VSBYS RESTRICTIONS WILL LIKELY DROP NO LOWER THAN MVFR CAT AT REMAINING TERMINALS AS AIRMASS IS DRIER. UPR LO WILL CONTINUE TO SHIFT EAST INTO WEST VIRGINIA DURING THE DAY SUNDAY. WITH STILL SOME WEAK INSTABILITY AND COOLER AIR ALOFT IN THE REGION...EXPECT SCT -SHRA WILL DVLP WITH DAYTIME HEATING DURING AFTN HOURS. HAVE MAINTAINED VCSH FOR ALL OF THE TERMINALS...BUT WOULD APPEAR THAT KCMH/KLCK/KILN STAND THE BEST CHANCE AT SEEING PCPN AS SFC LO SLIDES SE ACRS ERN OH. CLOUDS WILL DIMINISH DURING THE EVNG WITH POSSIBILITY AT SKIES GOING MSTLY CLR. OUTLOOK...MVFR CEILINGS WILL BE POSSIBLE IN SCATTERED SHOWERS AND THUNDERSTORMS LATE TUESDAY NIGHT AND WEDNESDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...RYAN AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 1043 AM CDT SUN APR 20 2008 .UPDATE... INHERITED GRIDS LOOK TO BE IN LINE WITH CURRENT OBSERVATIONS AND NUMERICAL GUIDANCE. THE MAIN UPDATE WAS TO LOWER HIGH TEMPERATURES SLIGHTLY FOR SUNDAY...SINCE LOW STRATUS HAS SPREAD ACROSS THE WESTERN PART OF THE STATE AND SCATTERED SHOWERS SHOULD SLOW DAYTIME HEATING A BIT. && .PREV DISCUSSION... /ISSUED 418 AM CDT SUN APR 20 2008/ SHORT TERM...TODAY THROUGH TUESDAY NIGHT... MAIN FOCUS TODAY INCLUDES STRONG WINDS THIS MORNING WITH WIND ADVISORY AND RED FLAG WARNING WARRANTED. SEE FIRE WEATHER DISCUSSION FOR RED FLAG DETAILS. THEN FOCUS SHIFTS TO PRECIPITATION CHANCES WITH SURFACE TROUGH/FRONT AND VIGOROUS UPPER LEVEL LOW/TROUGH WITH THUNDERSHOWERS AND RAIN AND SNOW SHOWERS. CURRENTLY...INVERTED TROUGH/COLD FRONT EXTENDED FROM A LOW IN WYOMING NORTHEASTWARD THROUGH EASTERN MONTANA TO SOUTH CENTRAL SASKATCHEWAN. BY NOON THE FRONT SHOULD BE OVER FAR WESTERN COUNTIES OF NORTH DAKOTA...AND BY EVENING NEAR DICKINSON TO EAST OF WILLISTON. BY MONDAY MORNING THE FRONT SHOULD BE APPROACHING THE RED RIVER VALLEY. CURRENTLY SOUTHEAST WINDS OF 15 TO 20 MPH WITH SOME HIGHER GUSTS...EXCEPT DICKINSON WHICH REPORTED 35 MPH GUSTING TO OVER 45 MPH. THINKING WINDS THERE SHOULD DECREASE DURING THE MORNING. WILL ISSUE WIND ADVISORY MY CENTRAL AND EASTERN COUNTIES...ONE BEGINNING 15Z AND THE JAMESTOWN AREA BEGINNING 18Z. EXPECTING ENOUGH INSTABILITY FOR THUNDERSTORMS THIS AFTERNOON OVER THE WESTERN HALF OF THE STATE...THEN RAIN AND SNOW SHOWERS SPREADING WEST TO EAST TONIGHT AS COLD AIR MOVES IN BEHIND THE COLD FRONT. MODELS HAVE CONSISTENTLY PUT GOOD PRECIP AMOUNTS OF 1/4 TO 1/2 INCH OVER NORTHWEST AND NORTH CENTRAL...WITH LESS THAN A TENTH OF AN INCH SOUTHERN COUNTIES. WEST WINDS MONDAY WITH A CHANCE OF SHOWERS AS UPPER LEVEL VORT ENERGY MOVES ACROSS THE STATE AND THE UPPER LOW LIFTS NORTH INTO CANADA. LONG TERM...WEDNESDAY THROUGH SATURDAY UNSETTLED PATTERN IN THE EXTENDED PERIOD. MODELS BEGIN THE EXTENDED PERIOD IN PRETTY GOOD AGREEMENT WITH HIGH PRESSURE SITUATED OVER THE REGION AND A CLOSED UPPER LOW SITUATED JUST OFFSHORE OF THE WA/OR COAST. WEDNESDAY LOOKS TO BE DRY AND A LITTLE WARMER ACROSS THE SOUTH THAN THE PREVIOUS FORECAST AS SOUTHERLY RETURN FLOW DEVELOPS DURING THE DAY AHEAD OF SURFACE LOW PRESSURE THAT DEVELOPS OVER THE NORTHERN AND CENTRAL HIGH PLAINS IN A BROAD SOUTHWEST UPPER FLOW PATTERN. THIS SURFACE LOW MOVES INTO THE NORTHERN PLAINS WEDNESDAY NIGHT BRINGING A CHANCE OF SHOWERS TO THE AREA. APPEARS TO BE ENOUGH STABILITY FOR SOME THUNDER ACROSS THE SOUTH...AS WELL AS ENOUGH COLD AIR FOR A RAIN/SNOW MIX IN THE WEST LATE WEDNESDAY NIGHT. THE ECMWF IS A BIT QUICKER THAN THE GFS AT THIS POINT BUT STILL ENOUGH AGREEMENT ON QPF PATTERN TO RAISE POPS INTO THE CHANCE CATEGORY ON WEDNESDAY NIGHT. THE GLOBAL GEM ALSO SUPPORTS THIS SCENARIO. MODELS BEGIN TO DIVERGE BEYOND THIS POINT WITH THE ECMWF AND GLOBAL GEM BRINGING AND END TO THE PRECIPITATION FROM WEST TO EAST ON THURSDAY AS THE SYSTEM HEADS EAST. THE GFS ON THE OTHER HAND SLOWS THE SURFACE SYSTEM AS THE UPPER TROUGH CLOSES OFF OVER NORTH DAKOTA BRINGING SIGNIFICANT RAIN AND SNOW TO THE AREA THURSDAY AND THURSDAY NIGHT. THE GFS HAS BEEN THE LEAST CONSISTENT OF THE MODELS AND HAVE LEANED TOWARD AN ECMWF GLOBAL GEM SOLUTION HERE. THUS WE DID KEEP A CHANCE OF RAIN AND SNOW OVER THE CWA ON THURSDAY BUT WENT DRIER THURSDAY NIGHT WITH MAINLY SLIGHT CHANCE POPS. BEYOND THE DAY 4-5 PERIOD...THE GFS KEEPS A COOL AIRMASS OVER THE REGION IN A NORTHWEST FLOW. ECMWF IS MORE ZONAL AND BRINGS A BRIEF WARM UP ON SATURDAY BEFORE COOLING TEMPERATURES DOWN AGAIN ON SUNDAY. AVIATION... SEVERAL PROBLEMS TO DEAL WITH IN THE AVIATION FORECAST TODAY. FIRST WILL BE WINDS AS A LOW PRESSURE SYSTEM CURRENTLY OVER SOUTHEAST MONTANA MAKES IT WAY EAST ACROSS THE CWA BY THE END OF THE 24 HOUR PERIOD. STRONG SOUTHEAST FLOW AHEAD OF THE SYSTEM WILL TURN WEST BEHIND THE SYSTEM. WILL USE LATEST RUC AND NAM WIND GUIDANCE FOR A START ON WIND FORECAST. SECOND PROBLEM WILL BE SHOWER AND POSSIBLE THUNDERSTORM DEVELOPMENT ALONG AND BEHIND THE COLD FRONT THIS AFTERNOON AND EVENING. WILL LIKELY CARRY A PROB30 GROUP FOR THUNDERSTORM ACTIVITY THIS AFTERNOON AND EVENING. AND FINALLY LOW CEILINGS AND VSBYS IN FROZEN PRECIPITATION LATE IN THE PERIOD. WILL HIT NORTHERN ZONES THE HARDEST WITH LOWER CIGS/VSBYS LATE TONIGHT. FIRE WEATHER... STRONG WINDS AND LOW RELATIVE HUMIDITIES ON SATURDAY GAVE RISE TO RED FLAG CONDITIONS. SEVERAL FIRES IGNITED AND WERE DIFFICULT TO CONTROL. WINDS WERE 15 TO 25 MPH AND GUSTY WITH MINIMUM RELATIVE HUMIDITIES OF 15 TO 22 PERCENT. FOR TODAY...EXPECTING WINDS OF 25 TO 35 MPH WITH GUSTS TO 45 MPH TODAY OVER ALL BUT THE FAR WESTERN COUNTIES. THE TROUGH/FRONT IS EXPECTED TO MOVE INTO WESTERN NORTH DAKOTA AROUND NOON AND THE SOUTHEAST WINDS WILL DECREASE DURING THE MORNING...THEN BECOME WESTERLY 15 TO 20 MPH THIS AFTERNOON. FROM ROUGHLY BURKE COUNTY TO GRANT/SIOUX COUNTIES EXPECTING SOUTHEAST WINDS TO INCREASE DURING THE MORNING AND REMAIN IN WIND ADVISORY CRITERIA THROUGH 10 PM CDT. THE MAIN FLY IN THE OINTMENT IS RELATIVE HUMIDITIES...WHICH ARE EXPECTED TO DROP TO 35 TO 40 PERCENT THIS AFTERNOON. THIS RELATIVE HUMIDITY WOULD NORMALLY BE TOO HIGH FOR RED FLAG CRITERIA...HOWEVER BECAUSE OF DORMANT/DRY VEGETATION WITH LITTLE OR NO GREENUP REPORTED...AND SUCH STRONG WINDS EXPECTED...WILL ISSUE THE RED FLAG BEGINNING AROUND 10 AM CDT THIS MORNING AND CONTINUING UNTIL 10 PM CDT TONIGHT. AS THE COLD FRONT PUSHES EASTWARD INTO THE STATE THIS AFTERNOON AND EVENING...THUNDERSTORMS SHOULD BECOME MORE WIDESPREAD...AND THE LOWER LEVELS SHOULD BECOME MORE CONDUCIVE TO PRECIPITATION REACHING THE GROUND. LIGHTNING STRIKES ARE POSSIBLE AND WILL BE A HAZARD WITH DRY FUEL CONDITIONS. PRECIPITATION SHOULD CHANGE OVER INTO A RAIN AND SNOW MIX BEHIND THE COLD FRONT TONIGHT. && .BIS WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 10 PM CDT /9 PM MDT/ THIS EVENING FOR NDZ002>005-010>013-019>023-025-034>037-042-045>048-050-051. WIND ADVISORY UNTIL 10 PM CDT /9 PM MDT/ THIS EVENING FOR NDZ002>005-010>013-019>023-034>036-042-045>047-050. WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR NDZ025-037-048- 051. WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR NDZ018- 033-041-044. && $$ JWS nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1020 AM CDT SUN APR 20 2008 .UPDATE... AGAIN TODAY MADE SOME MINOR CHANGES TO TODAYS GRIDS BASED ON MORNING TRENDS AND LATEST RUC. MORE CLOUD COVER WILL MAKE AFTN HIGH TEMP FORECAST A LITTLE MORE TRICKY TODAY... BUT THICKER BATCH OF CLOUDS WILL SHIFT EAST LATER TODAY AND MANY LOCATIONS SHOULD GET NEAR YESTERDAYS READINGS. WINDS WILL ALSO BECOME QUITE STRONG THIS AFTN... BUT THESE SHOULD AID IN INCREASING LOW LEVEL MOISTURE WHICH WILL KEEP AFTN HUMIDITIES FROM DROPPING TOO MUCH. STILL APPEARS THAT WE CAN GO WITHOUT ANY FIRE WX HEADLINES TODAY. UPDATES OUT SHORTLY. 30 --------------------------------------------------- 350 AM CDT SUN APR 20 2008 .DISCUSSION... THE UPPER RIDGE OVER THE SOUTHERN PLAINS WILL BE SHIFTING EAST OF THE AREA TODAY AS A LARGE UPPER LOW DOMINATES NEARLY THE WESTERN HALF OF THE COUNTRY. A DEEPENING SURFACE LOW PRESSURE TROUGH ALONG THE LEE OF THE ROCKIES WILL RESULT IN INCREASING SOUTH WINDS OVER THE AREA TODAY. THE STRONG WINDS WILL BEGIN PULLING GULF MOISTURE NORTH TOWARDS THE AREA... ALTHOUGH WITH 60 DEGREE DEWPOINTS JUST NOW REACHING THE LOWER TEXAS COAST... THE NAM MAY BE A LITTLE FAST IN PULLING 60 DEWPOINTS INTO WEST CENTRAL OKLAHOMA BY LATE AFTERNOON. MEANWHILE... A LEAD SHORT WAVE MOVING AROUND THE WESTERN LOW WILL TRACK MAINLY TO THE NORTH OF OUR AREA AS IT LIFTS NE THROUGH THE CENTRAL AND NORTHERN PLAINS. TO OUR SOUTH... A SECOND UPPER WAVE THAT WILL BE MOVING EAST OUT OF NORTHERN MEXICO BUT IT WILL LIKELY STAY TO OUR SOUTH IN TEXAS. IT STILL APPEARS THAT THE DRYLINE WILL BECOME ESTABLISHED JUST WEST OF THE CWA THIS AFTERNOON WHICH IN TURN SHOULD KEEP HUMIDITIES ABOVE 20 PCT IN FAR WESTERN PARTS OF OK AND N-TX. WHILE WILDFIRE CONCERNS WILL BE HEIGHTENED BECAUSE OF THE STRONGER WINDS... THE INCREASING LOW LEVEL MOISTURE WILL LIKELY HELP TO KEEP CONDITIONS BELOW CRITICAL LEVELS. OVER THE NEXT FEW DAYS... WE WILL SEE MUCH OF THE ENERGY ASSOCIATED WITH THE LARGE WESTERN LOW CONTINUE TO TRACK MAINLY TO THE NORTH OF THE AREA... BUT CLOSE ENOUGH TO PUSH AN OCCASIONAL FRONT INTO THE SOUTHERN PLAINS. THE FIRST WEAK COLD FRONT WILL MOVE THROUGH ABOUT THE WESTERN HALF OF THE CWA EARLY MONDAY BEFORE BECOMING STATIONARY BY LATE AFTERNOON. WE WILL MAINTAIN LOW POPS FOR PARTS OF NORTH CENTRAL OKLAHOMA FOR MONDAY NIGHT WHERE LIFTING OVER THE FRONT MIGHT GENERATE A STORM OR TWO. HOWEVER... MODEL SOUNDINGS CONTINUE TO SHOW A DECENT CAP OVER MOST OF THE AREA THAT WOULD SUPPRESS MORE WIDESPREAD CONVECTION. ANOTHER WAVE MOVING THROUGH THE CENTRAL PLAINS ON TUESDAY SHOULD HELP PUSH THE FRONT BACK SOUTH ACROSS AREA MONDAY NIGHT AND TUESDAY. WE WILL MAINTAIN A MENTION OF T-STORMS OVER AT LEAST PART OF THE AREA FOR MUCH OF THE UPCOMING WORK WEEK AS UPPER WAVES MOVING OUT OF THE LARGE WESTERN TROUGH CONTINUE TO BRUSH THE AREA... WHILE VARIOUS FRONTS TRAVERSE BACK AND FORTH THROUGH THE AREA. THE MAIN ADJUSTMENTS MADE TO THE GFS MAV/MEX GUIDANCE INCLUDED... MONDAY NIGHT - PULLING THE MAV 20 PCT POPS A LITTLE FARTHER WEST TO INCLUDE SOME OF OUR SE ZONES WHERE CONVERGENCE ON A FRONT AND DEEPER MOISTURE MAY BE SUFFICIENT TO OVERCOME THE CAP IN A FEW PLACES. TUESDAY - COOLED THE MAV HIGH TEMPS IN THE NORTH TO ACCOUNT FOR THE COLD FRONT MOVING THROUGH THE AREA AND TO IMPROVE CONSISTENCY WITH GFE GRIDDED TEMPS AND SURROUNDING OFFICES. THURSDAY - SMOOTHED OUT AN APPARENT LOCAL TEMPERATURE ANOMALY DEPICTED IN NW WOODWARD COUNTY WHERE THE MEX MAX TEMPERATURE GUIDANCE WAS 8 TO 10 DEGREES COOLER THAN NEARBY SURROUNDING AREAS. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 82 59 81 61 / 0 10 0 10 HOBART OK 83 58 86 58 / 0 10 10 10 WICHITA FALLS TX 84 65 88 62 / 0 10 0 10 GAGE OK 87 48 83 51 / 0 10 10 10 PONCA CITY OK 81 60 79 62 / 0 10 0 20 DURANT OK 79 63 82 67 / 0 10 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 26/32 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 300 PM MDT SUN APR 20 2008 .SHORT TERM...FAIRLY STRONG SOUTHWEST GRADIENT ACROSS COLORADO AT PRESENT DUE TO UPPER TROUGH OVER PACIFIC NORTHWEST. GUSTY SOUTHWEST WINDS OCCURRING OVER CWA DUE TO GOOD MIXING. HUMIDITY READINGS HAVE BOTTOMED OUT AROUND 10 PERCENT. FIRE WEATHER CONCERNS REMAIN CRITICAL OVER THE PLAINS. RUC CONTINUES THE GUSTY WINDS THROUGH AT LEAST 02Z...SO RED FLAG WARNING WILL CONTINUE. CONDITIONS SHOULD IMPROVE AT THAT TIME AS HUMIDITY LEVELS BEGIN TO INCREASE. MODELS CONTINUE TO SHOW COLD FRONT MOVING ACROSS MOUNTAINS THIS EVENING...THEN ONTO THE PLAINS AROUND 06Z. SHOULD SEE WINDS BECOME WESTERLY ACROSS THE MOUNTAINS AFTER FRONT PASSES THROUGH. MODEL CROSS SECTIONS INDICATING LITTLE IF ANY MOISTURE THROUGH ABOUT 12Z. WILL DROP THE LOW POPS FOR THE MOUNTAINS TONIGHT. AS FOR THE PLAINS...WINDS BECOME NORTHERLY. NO POPS AS AIRMASS DRY. ON MONDAY...MODELS CONTINUE TO SHOW WEAK WAVE MOVING ACROSS AREA AS NOTED BY AREA OF QG ASCENT. SOME MID LEVEL ASSOCIATED WITH THIS WAVE. COULD SEE SOME PRECIP DEVELOP ACROSS MOUNTAINS...CURRENT LOW POPS SEEM REASONABLE AT THIS POINT. FOR THE PLAINS...SURFACE FLOW EXPECTED TO BECOME SOUTHEAST BY AFTERNOON...WHICH COULD LEAD TO SOME WEAK CONVERGENCE ALONG FOOTHILLS. WITH WEAK ASCENT AND LAPSE RATES AROUND 8 C/KM...CAN`T RULE OUT THE POSSIBILITY OF A FEW STORMS DEVELOPING...THOUGH FORECAST CAPES ARE MINIMAL. CURRENT FORECAST ALREADY HAS A SLIGHT CHANCE OF STORMS FOR FOOTHILLS AND ADJACENT PLAINS FOR THE AFTERNOON...WILL CONTINUE. NOT MUCH IN THE WAY OF LOW LEVEL MOISTURE...SO ANY PRECIPITATION WILL BE LIGHT. COULD BE SOME GUSTY DOWNDRAFTS WITH THE STORMS. TEMPERATURE AND THICKNESS PROGS SHOW TEMPERATURES ABOUT 10 DEGREES COOLER THAN TODAY`S READINGS. CURRENT TEMPERATURE GRIDS SEEM ON TRACK. NOT EXPECTING ANY FIRE WEATHER CONCERNS AS WINDS AND HUMIDITY SHOULD BE BELOW CRITICAL LEVELS. .LONG TERM...MODELS HAVE STRONG WEST-NORTHWESTERLY FLOW ALOFT OVER THE FORECAST AREA MONDAY NIGHT...WITH A JET MAX TO OUR IMMEDIATE NORTH. ON TUESDAY THE UPPER LEVEL FLOW DECREASES QUITE A BIT AND BECOMES MORE SOUTHWESTERLY. THIS CONTINUES INTO EARLY WEDNESDAY. LATER WEDNESDAY...THE FLOW INCREASES A BIT AND BECOMES MORE WESTERLY. DOWNWARD SYNOPTIC SCALE ENERGY IS PROGGED FOR THE FORECAST AREA MONDAY NIGHT AND TUESDAY. FROM TUESDAY NIGHT THROUGH WEDNESDAY EVENING...WEAK UPWARD MOTION IS PROGGED FOR THE FORECAST AREA. THE BOUNDARY LAYER FLOW IS FAIRLY BENIGN MONDAY NIGHT THROUGH TUESDAY NIGHT. BY WEDNESDAY...LOWER PRESSURE EAST OF THE MOUNTAINS INDICATES SOME SOUTHWESTERLY DOWNSLOPING FLOW FOR THE FOOTHILLS AND PLAINS. FOR MOISTURE...THERE IS A BIT IN THE MID AND UPPER LEVELS MONDAY NIGHT THROUGH WEDNESDAY. THERE IS A BIT OF LOW LEVEL MOISTURE OVER THE PLAINS WEDNESDAY. THERE IS A THETA-E AXIS ACROSS THE EASTERN PLAINS WEDNESDAY AFTERNOON. THE STEEPEST LAPSE RATES ARE PROGGED ON WEDNESDAY. FORECAST SOUNDINGS SHOW A TINY BIT OF CAPE MONDAY EVENING OVER THE CENTRAL FORECAST AREA. THERE IS ALSO SOME LIMITED CAPE OVER THE MOUNTAINS AND FOOTHILLS LATE DAY WEDNESDAY...WITH FAIRLY DECENT CAPE VALUES OVER THE FAR EASTERN BORDER WEDNESDAY AFTERNOON. NO POPS MONDAY NIGHT THROUGH WEDNESDAY MORNING JUST NOT ENOUGH MOISTURE. WILL GO 10-20% WEDNESDAY AFTERNOON INTO THE EVENING WITH THUNDER MENTIONED AS WELL. FOR TEMPERATURES... TUESDAY`S HIGHS ARE 3-4 C WARMER THAN MONDAY`S. WEDNESDAY`S HIGHS ARE 2-4 C WARMER THAN TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH SUNDAY...MODELS SHOW AN UPPER TROUGH PUSH ACROSS THURSDAY INTO EARLY FRIDAY. THERE IS NORTHWESTERLY FLOW ALOFT FRIDAY. THEN AN UPPER RIDGE FOR THE WEEKEND. WILL DRY THURSDAY OUT A BIT ON THE GRIDS AND LEAVE THE REST OF THE POPS WITH THE TROUGH AS IS. FRIDAY IS THE ONLY COOL DAY. WILL WARM THURSDAY UP AND KEEP READINGS A BIT A ABOVE NORMALS FOR THE LAST DAY...SUNDAY. && .AVIATION...WEST SOUTHWEST WINDS OF 15-25 KTS WITH SOME GUSTS TO 30 KTS TO CONTINUE THROUGH ABOUT 03Z BEFORE DECREASING. A COLD FRONT WILL MOVE ACROSS THE AREA AROUND 06Z WITH WINDS BECOMING NORTHERLY. FRONT WILL BE DRY...SO VFR CONDITIONS EXPECTED WITH NO PRECIP. A FEW HIGH BASED STORMS COULD DEVELOP AFTER 18Z ALONG FOOTHILLS... SLOWLY DRIFTING ACROSS ADJACENT PLAINS BETWEEN 21Z AND 00Z. GUSTY OUTFLOW WINDS TO AROUND 30KTS POSSIBLE FROM THE STORMS...WHICH COULD AFFECT AREA AIRPORTS. ANY AREA PRECIPITATION WILL BE LIGHT. && .BOU WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING UNTIL 8 PM FOR NORTHEAST PLAINS...COZ238>251 FOR GUSTY WIND AND LOW HUMIDITY. && $$ D-L/RJK co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 242 PM MDT SUN APR 20 2008 .SHORT TERM...TONIGHT THROUGH TUESDAY... SURFACE OBSERVATIONS AND RUC SHOW THE COLD FRONT THROUGH VERNAL AND PRICE...BUT JUST WEST OF CANYONLANDS AND HANKSVILLE. THE NORTHERN PORTION OF THE FRONT WILL CONTINUE EAST AND MOVE THROUGH NORTHWEST COLORADO THIS EVENING. IT SHOULD REACH ROUTT COUNTY BY ABOUT 8 PM MDT. THE SOUTHERN PORTION...SOUTH OF ABOUT INTERSTATE 70...WILL CONTINUE LAGGING BACK TO THE SOUTHWEST AND SLOW ITS EASTERLY PROGRESS. EXPECT THE FRONT TO HANGUP LATE TONIGHT SOMEWHERE BETWEEN GRAND JUNCTION AND MONTROSE...AND STAY NORTH OF MONTICELLO. THE STRONG SOUTHWEST WINDS AND HEIGHTENED FIRE WEATHER CONCERNS WILL CONTINUE UNTIL THE WINDS DIMINISH ABOUT 9 PM. THERE IS NOT MUCH IN THE WAY OF CLOUD COVER WITH THIS SYSTEM...SO HAVE DECREASED CLOUDS AND POPS SIGNIFICANTLY FOR TONIGHT AND MONDAY. MONDAY THROUGH TUESDAY...WINDS ALOFT WILL SLOWLY DECREASE SO ANOTHER WIDESPREAD WIND ADVISORY WAS NOT ISSUED. INSTEAD...BELIEVE WINDS WILL BE STRONG ENOUGH FOR AN ADVISORY ONLY IN THE I-70 CORRIDOR EAST OF GRAND JUNCTION TO EDWARDS...CO ZONES 7 AND 8...MONDAY AFTERNOON AND EARLY EVENING. THE COLD FRONT WILL BE ABOUT PARALLEL TO THE WESTERLY FLOW AND WILL SLOUGH A BIT FURTHER SOUTH. MONDAY SHOULD BE A BIT COOLER AS A RESULT IN ALL BUT THE MOST SOUTHERN ZONES. ON TUESDAY THE FRONT SHOULD WAVE BACK TO THE NORTH AND AN POORLY DEFINED WARM FRONT. THIS SHOULD CONTINUE THE DECREASING WIND TREND...WHILE TEMPS INCREASE AGAIN WITH HUMIDITY STAYING LOW. .LONG TERM...TUESDAY NIGHT THROUGH SUNDAY... CONSISTENCY REMAINS GOOD AS LONG AS ONE THROWS OUT THE 06Z GFS BEYOND MIDWEEK. THERE STILL ARE A FEW MINOR TIMING DIFFERENCES...WITH THE MIDWEEK TROUGH PASSAGE AND COLD FRONT WAITING FOR THU AFTERNOON. THE 12Z CAME BACK IN LINE WITH THE 00Z ECMWF AND GFS RUNS IN BRINGING A FLAT RIDGE OVER THE WEST FOR THE LATTER HALF OF THE PERIOD. SOUTHWEST WINDS WILL AGAIN PICK UP WED AFTERNOON AS THE TROUGH STRENGTHENS TO OUR WEST. HOWEVER MODELS HAVE TRENDED MORE NORTHERLY WITH ITS TRACK ON THUR...AND WEAKER WITH ITS ASSOCIATED COLD FRONT. SO TWEAKED THE ALREADY LOW POPS DOWNWARDS...AND THURSDAYS TEMPERATURES UPWARDS. BEYOND THURSDAY...A WARMING TREND IS EXPECTED AS A RIDGE BUILDS OVER THE WEST COAST THEN SHIFTS EASTWARD THROUGH THE REMAINDER OF THE PERIOD. && .AVIATION... VFR WILL CONTINUE THROUGH MONDAY. HOWEVER...WINDY CONDITIONS WITH AFTERNOON GUSTS REACHING 40 KNOTS OVER THE RIDGES WILL BE COMMON AND CAUSE WIDESPREAD TURBULENCE AND MOUNTAIN WAVES OVER AND IN THE LEE OF RIDGES. && .FIRE WEATHER (FROM SATURDAY AFTERNOON DISCUSSION)... WIDESPREAD GUSTY SW GRADIENT WINDS AND LOW RH CONTINUE THIS AFTERNOON. THE COLD FRONT SWEEPS ACROSS THE NORTH THIS EVENING AND BECOMES STATIONARY NEAR THE I-70 CORRIDOR. THIS WILL USHER IN A COOLER AIRMASS NORTH OF THE ROAN/TAVAPUTS FOR INCREASED RH MONDAY AFTERNOON. SOUTH OF THE FRONT...SURFACE-BASED INVERSIONS WILL SET UP QUICKLY AFTER SUNSET. BUT MIXING WILL BRING RED FLAG WARNING CONDITIONS AGAIN LATE MONDAY MORNING. AFTERNOON HUMIDITIES OF 8-15 PCT WITH WIND GUSTS 35-45 MPH IN THESE AREAS WILL AGAIN CREATE DANGEROUS FIRE CONDITIONS. COORDINATION WITH LAND MGMT AGENCIES INDICATE THE MAIN CONCERN IS THE BURNING OF DITCHES OF AGRICULTURAL FIELDS...WHERE DEAD/DRY VEGETATION WILL FUEL RAPID FIRE GROWTH. WINDY CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THURSDAY...BUT COOLER TEMPS FORECAST SHOULD RESULT IN SOMEWHAT HIGHER HUMIDITIES. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...RED FLAG WARNING IN EFFECT UNTIL 9 PM MDT TODAY FOR FIRE WEATHER ZONES 201/203/205/207 BELOW 6500 FEET. RED FLAG WARNING IN EFFECT FROM 11 AM UNTIL 7 PM MDT MONDAY FOR FIRE WEATHER ZONES 203/205/207 BELOW 6500 FEET. WIND ADVISORY IN EFFECT FOR ALL LOWER ELEVATIONS ZONES TODAY FROM NOON UNTIL 9 PM MDT...ZONES 1/2/6/7/8/11/14/20/ 21/22/23. WIND ADVISORY IN EFFECT MONDAY FROM 11 AM 7 PM MDT...FOR THE INTERSTATE 70 CORRIDOR FROM CAMEO TO EDWARDS...ZONES 7 AND 8. .UT...RED FLAG WARNING IN EFFECT UNTIL 9 PM MDT TODAY FOR FIRE WEATHER ZONE 443 BELOW 5500 FEET. WIND ADVISORY IN EFFECT FOR ALL LOWER ELEVATIONS ZONES TODAY FROM NOON UNTIL 9 PM MDT...ZONES 24/27/29/22. $$ SHORT TERM.....CJC LONG TERM......ELH AVIATION.......CJC FIRE WEATHER...JOE co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 345 PM EDT SUN APR 20 2008 .SYNOPSIS... THE RIDGE OF HIGH PRESSURE WILL REMAIN IN CONTROL HEADING INTO THE NEW WEEK. HOWEVER...WITH COOLER AIR COMING OFF THE ATLANTIC...LOWER CLOUD COVER WILL IMPACT THE MIDDLE HUDSON VALLEY AND PORTIONS OF NORTHWEST CONNECTICUT. THE NEXT CHANCE FOR RAINFALL ARRIVES LATE WEDNESDAY WITH AN APPROACH OF A COLD FRONT. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE PICTURES SHOW THE MARINE STRATUS SLOWING BUT SURELY ERODING AWAY FROM THE EAST IN OUR SOUTHERN AREAS. LATEST OBS STILL HAD KPOU CLOUDY BUT EVEN THERE...SOME SUNSHINE SHOULD BREAK OUT SOON. EVEN WITH LIMITED SUNSHINE...TEMPERATURES WILL REMAIN QUITE A BIT LOWER THAN THOSE OF YESTERDAY...MAINLY IN THE 60S. THE CUTOFF LOW...CENTERED OVER SW VA...CONTINUES TO SLOWLY "WOBBLE" TO THE ESE AND THE HEAVY SWATH OF RAIN ASSOCIATED WITH IT...SHOULD REMAIN TO OUR SOUTH. OVER THE REMAINDER OF THE COUNTY WARNING AREA (CWA)...NOTHING MORE THAN HIGH CLOUDS AND SOME HAZE WITH A GOOD DEAL OF SUNSHINE. TEMPERATURES ARE A BIT COOLER THAN YESTERDAY BUT NOT AS MUCH...TOPPING OUT IN THE 70S. TONIGHT...ONCE THE SUN GOES DOWN...THE STRATUS WILL LIKELY REFORM TO OUR SOUTH UNDERNEATH AN INCREASING AND LOWER INVERSION...AS THE MARINE AIR GETS TRAPPED UNDERNEATH IT. THE STRATUS MIGHT SNEAK A LITTLE FURTHER UP THE HUDSON VALLEY...BUT FOR NOW...BELIEVE IT WILL ONCE AGAIN STAY JUST SOUTH OF THE TRI-CITY AREA. THE MODEL SOUNDINGS DO INDICATE WHAT STRATUS CLOUDS THAT DO FORM... SHOULD BE VERY SHALLOW AND NOT THICK ENOUGH TO SUPPORT EVEN ANY DRIZZLE...SO LEFT IT OUT. WENT CLOSE TO MAV LOWS OVERNIGHT...EXCEPT A LITTLE HIGHER IN THE CAPITAL DISTRICT WHERE WE THINK A BREEZE MIGHT PERSIST A BIT LONGER MITIGATING A RADIATIONAL LOSS OF HEAT FLUX. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... TOMORROW...THE CUTOFF LOW IS FORECAST TO CONTINUE TO SLOWLY SINK SOUTHWARD BY BOTH THE 12Z NAM AND GFS MODELS. AT THE SAME TIME...HIGH PRESSURE ALOFT IS ACTUALLY FORECAST BY BOTH MODELS TO REBUILD OVER OUR CWA. THIS WILL INCREASE SUBSIDENCE ONCE AGAIN. THIS SUBSIDENCE IN CONJUNCTION WITH THE STRONG LATE APRIL SUNSHINE (HAVING THE SAME EQUIVALENT AS SUNSHINE IN LATE AUGUST)...SHOULD BE ENOUGH TO BURN OFF ANY LOW STRATUS CLOUDS...LEAVING ONLY SOME RESIDUAL HIGH AND MID LEVEL ONES...WHICH HAVE BLOWN OFF THE UPPER AIR LOW. H850 TEMPERATURES LOOK TO HOLD AROUND +8C. WITH GOOD MIXING...TEMPERATURES WILL TOP OUT WITHIN A FEW DEGREES OF 70 IN VALLEY LOCATIONS...AND 60S OVER THE HIGHER TERRAIN. WENT CLOSE TO MAV VALUES. VERY LITTLE LOOKS TO CHANGE IN TERMS OF THE SYNOPTIC SETUP AND SENSIBLE WEATHER THROUGH TUESDAY NIGHT. THE CUTOFF LO9W WILL CONTINUE TO VERY SLOW DRIFT SOUTH AND EAST...BY THIS POINT...OFF THE SOUTH CAROLINA COASTLINE. HIGH PRESSURE WILL REMAIN OVER OUR REGION BOTH AT THE SURFACE AND ALOFT WITH VERY LITTLE CHANGE IN TEMPERATURES THROUGH THE COLUMN. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH NO RAIN. WENT VERY CLOSE TO MAV GUIDANCE DURING THESE TIME FRAMES. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... THE EXTENDED PERIOD BEGINS WITH RIDGING OVER THE EASTERN SEABOARD WHILE A SHORTWAVE MOVES EASTWARD FROM JUST NORTH OF THE GREAT LAKES TOWARDS EASTERN CANADA. 850 MB TEMPS WILL CONTINUE TO RUN 1-2 STD ABOVE NORMAL...WITH VALUES AROUND 8 DEGREES C. THIS SHOULD ALLOW FOR HIGHS TO RANGE FROM THE MIDDLE 60S IN THE DACKS TO THE MIDDLE 70S IN THE MID HUDSON VALLEY. THE AFOREMENTIONED DISTURBANCE WILL RUN INTO THE RIDGE...FLATTENING THE 500MB FLOW BY WEDNESDAY NIGHT. AT THE SURFACE...THIS FEATURE WILL DRAG A WEAK COLD FRONT THROUGH THE REGION FOR THE SAME TIME PERIOD. WITH THE BEST UPPER LEVEL DYNAMICS LIFTING NORTH ACROSS QUEBEC AND LITTLE MOISTURE TO WORK WITH...THIS SYSTEM SHOULD ONLY PRODUCE SCT SHOWERS AT BEST. 12Z GFS ENSEMBLES SHOW THE OPERATIONAL RUN TO BE THE MOST PESSIMISTIC WITH PRECIP...SO AM CONTINUING ONLY LOW CHC POPS OVER THE NORTHERN 3/4 OF THE CWA...WITH SLT CHC POPS ACROSS THE FAR SOUTH. THE GFS SHOWS LIS DROPPING TO JUST NEAR ZERO AND WITH ABOUT 100-200 J/KG OF CAPE PROJECTED. SOME T-STORM ACTIVITY COULD BE POSSIBLE...BUT WITH CONFIDENCE BEING LOW...WILL CONTINUE TO LEAVE IT OUT OF THE FORECAST FOR NOW. BEHIND THIS SYSTEM...CAA WILL DROP 850 TEMPS...ALLOWING LOWER MAX TEMPS ON THURS...YET STILL VERY COMFORTABLE AND STILL SEVERAL DEGREES ABOVE NORMAL. PLENTY OF SUNSHINE SHOULD RETURN FOR THURSDAY AS WELL AS A 1026 MB HIGH RAPIDLY MOVES IN BEHIND THE SYSTEM. THE NEXT FEATURE TO WATCH WILL BE A SYSTEM MOVING ACROSS THE PLAINS FOR THE WEEKEND. YESTERDAYS MODELS RUNS SEEMED TO CUT THIS FEATURE OFF QUICKER...SLOWING ITS EASTWARD PROGRESS. TODAY/S 12Z EURO SHOWS THIS NEXT FEATURE BEING A LOT MORE PROGRESSIVE...MOVING IT ACROSS THE REGION ON SAT NIGHT INTO SUNDAY...WHILE THE 12Z GFS CONTINUES TO SHOWS THIS FEATURE CLOSING OFF OVER THE GREAT LAKES...AND AFFECTING OUR WEATHER STARTING LATE ON SATURDAY AND CONTINUING INTO EARLY NEXT WEEK. WITH UNCERTAINTIES REGARDING THIS SYSTEM...WILL CONTINUE TO SHOW JUST CHC POPS FOR -SHRA ACROSS THE CWA STARTING ON SATURDAY AND CONTINUING THROUGH SUNDAY. IN GENERAL...THE LONG TERM PERIOD LOOKS TO HAVE PRECIP AVERAGING BELOW NORMAL AND TEMPERATURES AVERAGING ABOVE NORMAL. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... FOR KGFL TO KALB...VFR CONDITIONS EXPECTED WITH LIGHT WINDS AND NEAR IDEAL FAVORABLE AVIATION CONDITIONS. THIS DOES CHANGE FOR KPOU. WITH SOUTHEAST WIND TRAJECTORIES ORIGINATING FROM THE MARINE INFLUENCE OFF THE COOLER WATERS OF LONG ISLAND SOUND AND THE ATLANTIC...A LAYER OF LOW STRATUS WILL REMAIN PROBLEMATIC. LATEST FORECAST SOUNDINGS FROM THE NAM/WRF AND RUC13 SUGGEST THIS IFR CEILING WILL BECOME PREVALENT OVERNIGHT AND WILL REINTRODUCE THOSE 1000 FOOT CIGS. CONDITIONS WILL IMPROVE THROUGH THE DAYLIGHT HOURS MONDAY MORNING. OUTLOOK... MON PM-WED...VFR...NO SIGNIFICANT WEATHER. WED NIGHT...VFR/MVFR WITH A CHANCE FOR RAIN SHOWERS. THU...VFR...NO SIGNIFICANT WEATHER. && .FIRE WEATHER... DRY WEATHER IS FORECAST AT THROUGH TUESDAY NIGHT. THE NEXT CHANCE OF ANY SIGNIFICANT RAIN WILL HAVE TO WAIT UNTIL A COLD FRONT CROSSES THE REGION BY WEDNESDAY. A MARINE AIRMASS DID BRING HIGHER RH HUMIDITY VALUES TO MOST OF THE REGION SOUTH TODAY...AS WELL AS STRATUS WELL TO THE SOUTH OF ALBANY. OVERALL...RH VALUES WERE ABOUT 20 PERCENT HIGHER THAN SATURDAY. RH VALUES WILL RECOVER TO BETWEEN 90 AND 100 PERCENT TONIGHT. WITH LESS OF A MARINE INFLUENCE...AFTERNOON RH VALUES WILL DROP BACK INTO THE 30S MOST PLACES ON MONDAY....THEN RECOVER TO BETWEEN 80 AND 90 PERCENT ON MONDAY NIGHT...THEN DROP BACK AROUND 30 PERCENT BY TUESDAY AFTERNOON. A SSE SURFACE WIND WILL DIMINISH TO LIGHT MOST PLACES OVERNIGHT...THEN RESUME FROM THE SE 5 TO 15 MPH ON MONDAY AND AGAIN TUESDAY AFTER BECOMING LIGHT OR CALM MONDAY NIGHT. && .HYDROLOGY... FLOOD WARNINGS REMAIN POSTED ALONG THE NORTHERN BRANCH OF THE HUDSON RIVER AT SCHUYLERVILLE AND FORT EDWARD...THE SCHROON RIVER AT RIVERBANK AND SACANDAGA RIVER AT THE RESERVOIR. WARM TEMPERATURES AND THE SNOWMELT ARE THE CULPRIT WITH STILL SEVERAL INCHES OF WATER EQUIVALENT REMAINING IN HERKIMER COUNTY /ADIRONDACKS/ INCLUDING THE SOUTHERN GREEN MOUNTAINS OF VERMONT. SO EXPECT RIVER LEVELS IN OUR NY CWA AT THESE LOCATIONS TO REMAIN HIGH INCLUDING INDIAN LAKE...NORTH CREEK AND PERHAPS THE WEST CANADA CREEK WITH THE RUNOFF FROM THE MOUNTAINS. WE WILL STILL REMAIN RATHER MILD SO UNTIL THE SNOWPACK COMPLETELY ERODES...RIVER LEVELS WILL REMAIN HIGH. THE NEXT CHANCE FOR RAINFALL ARRIVES LATE WEDNESDAY AND WEDNESDAY NIGHT. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...BGM NEAR TERM...HWJIV SHORT TERM...HWJIV LONG TERM...FRUGIS AVIATION...BGM FIRE WEATHER...HWJIV HYDROLOGY...BGM ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 122 PM EDT SUN APR 20 2008 .SYNOPSIS... HIGH PRESSURE NEAR NOVA SCOTIA WILL KEEP THE FAIR AND DRY WEATHER PATTERN IN PLACE ACROSS EASTERN NEW YORK AND WESTERN NEW ENGLAND TODAY THROUGH EARLY NEXT WEEK. HIGH TEMPERATURES THIS AFTERNOON WILL BE A LITTLE COOLER THAN YESTERDAY...DUE TO AN EAST TO SOUTHEASTERLY FLOW OF SLIGHTLY COOLER AIR...AND SOME HIGH CLOUDS ASSOCIATED WITH A LOW PRESSURE SYSTEM OVER THE MID ATLANTIC REGION. HIGH TEMPERATURES TODAY THROUGH TUESDAY WILL BE 10 TO 15 DEGREES ABOVE NORMAL FOR LATE APRIL. && .NEAR TERM /UNTIL 6 PM THIS AFTERNOON/... MARINE INFLUENCE CONTINUES TO PLAQUE THE MID HUDSON VALLEY WITH AN EXTENSIVE STRATUS DECK. THIS WILL CUT BACK ON HIGH TEMPERATURES AND CURRENT TRENDS FROM THE 1KM VISIBLE SUGGEST THIS CLOUD DECK IS ADVANCING NORTHWARD. WILL ADJUST CLOUD COVER UPWARD FOR THE ENTIRE CWA AND DROP TEMPERATURES ACCORDINGLY BY A FEW DEGREES. HOWEVER...WITH BREAKS AND THIN NATURE OF THE CLOUD COVER...TEMPERATURES INTO THE MOHAWK VALLEY AND NORTH OF THE MID HUDSON VALLEY SHOULD TAP OUT INTO THE LOWER 70S. OTHERWISE...NO OTHER CHANGES NEEDED AT THIS TIME. && .SHORT TERM /6 PM THIS AFTERNOON THROUGH TUESDAY NIGHT/... THE REX BLOCK WITH A RIDGE OVER THE NORTHEAST NORTH OR JUST POLEWARD OF THE CUTOFF LOW OVER THE MID ATLANTIC REGION CONTINUES TO HOLD THROUGH THE SHORT TERM. THE CUTOFF GETS STEERED AND DIRECTED FURTHER SOUTHEAST MONDAY INTO TUESDAY...THAT IT WILL BE PUSHED BACK TOWARD SC AND FL. MEANWHILE...THE CLOSED ANTICYCLONE AT H500 CONTINUES TO BE ANCHORED OVER NY AND NEW ENGLAND. MIN TEMPS SUNDAY EVENING WILL DEPEND ON HOW MUCH RADIATIONAL COOLING OCCURS. SOME CIRRUS WILL BE LINGERING AND THE BOUNDARY LAYER WINDS WILL BE CALM. WITH PARTLY CLOUDY CONDITIONS...WE LEANED TOWARDS THE GFSMOS MINS WITH 30S OVER THE HILLS...MTNS...SRN VT...AND THE LAKE GEORGE REGION....WITH LOWER TO MID 40S ELSEWHERE. MONDAY THROUGH TUESDAY...MORE PLEASANT WEATHER WITH MAX TEMPS STILL ABOUT 10-15 DEGREES ABOVE NORMAL ON MON WITH HIGH PRESSURE EAST OF THE GULF OF MAINE IN CONTROL. TUESDAY MORNING MINS WILL BE A BIT CHILLY WITH SOME DECENT RADIATIONAL COOLING WITH CALM AIR...MOSTLY CLEAR SKIES...AND DRY/PARCHED SOIL IN SOME LOCATIONS. WE WENT 1-3 DEGREES COOLER THAN THE GFSMOS TEMPS. TUESDAY TEMPS COULD SKIP UP A LITTLE WARMER IN THE MID 70S IN THE VALLEYS /60S OVER THE HILLS AND MTNS/ WITH GOOD DRY ADIABATIC MIXING FROM 850 MB /TEMPS AROUND +8C/ AND MOSTLY SUNNY CONDITIONS. TUESDAY NIGHT...A COLD FRONT APPROACHING FROM ERN ONTARIO...THE GREAT LAKES REGION AND THE MIDWEST ASSOCIATED WITH A BROAD UPPER LEVEL TROUGH...MAKES A RUN AT THE NORTHEAST. HOWEVER...THE FRONT LOOKS LIKE IT WILL GO THROUGH SOME FRONTALYSIS RUNNING INTO THE HIGH AMPLITUDE RIDGE OVER THE EAST COAST OF NORTH AMERICA. IT DOESN/T APPEAR ANY PCPN WITH THIS WEAKENING FRONT WILL OCCUR UNTIL LATE WED PM INTO THE EVENING /IF THAT/ BASED ON THE GFS/ECMWF. WE JUST INCREASED SOME CLOUDS AHEAD OF THIS BOUNDARY WED MORNING. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... ABOVE NORMAL TEMPERATURES WILL CONTINUE FOR THE EXTENDED PERIOD. THERE WILL BE A CHANCE FOR SOME SHOWERS WEDNESDAY AND WEDNESDAY NIGHT AS AN UPPER TROUGH/SHORT WAVE MOVES ACROSS THE GREAT LAKES AND NORTHERN NEW YORK STATE PUSHING INTO RIDGE. AT THE SURFACE A WEAKENING COLD FRONT WILL PUSH THROUGH AREA BRINGING A CHANCE FOR SHOWERS. THE RIDGE AMPLIFIES THURSDAY INTO FRIDAY. IN THE MEANTIME A STRONG PACIFIC SHORT WAVE WILL MOVE INTO THE WESTERN UNITED STATES. THE GFS AND ECMWF ARE IN BETTER AGREEMENT HANDLING THIS FEATURE BUT THERE STILL ARE FAIRLY LARGE DIFFERENCES. THE ECMWF HAS A MORE AMPLIFIED RIDGE WHILE THE GFS IS STRONGER WITH PACIFIC ENERGY ACTUALLY CLOSING OFF A LOW OVER THE UPPER MID WEST BY FRIDAY. BOTH MODELS BREAK RIDGE DOWN AS WE HEAD INTO THE WEEKEND BRINGING OUR NEXT CHANCE FOR RAIN AS THE LOW PRESSURE SYSTEM MOVES INTO THE REGION. && .AVIATION /18Z SUNDAY THROUGH THURSDAY/... FOR KGFL TO KALB...VFR CONDITIONS EXPECTED WITH LIGHT WINDS AND NEAR IDEAL FAVORABLE AVIATION CONDITIONS. THIS DOES CHANGE FOR KPOU. WITH SOUTHEAST WIND TRAJECTORIES ORIGINATING FROM THE MARINE INFLUENCE OFF THE COOLER WATERS OF LONG ISLAND SOUND AND THE ATLANTIC...A LAYER OF LOW STRATUS WILL REMAIN PROBLEMATIC. LATEST FORECAST SOUNDINGS FROM THE NAM/WRF AND RUC13 SUGGEST THIS IFR CEILING WILL BECOME PREVALENT OVERNIGHT AND WILL REINTRODUCE THOSE 1000 FOOT CIGS. CONDITIONS WILL IMPROVE THROUGH THE DAYLIGHT HOURS MONDAY MORNING. OUTLOOK... MON PM-WED...VFR...NO SIGNIFICANT WEATHER. WED NIGHT...VFR/MVFR WITH A CHANCE FOR RAIN SHOWERS. THU...VFR...NO SIGNIFICANT WEATHER. && .FIRE WEATHER... ...SOUTHEASTERLY WIND GUSTS TODAY UP TO 20 MPH IN PERSISTENT DRY PATTERN... HIGH PRESSURE NEAR NOVA SCOTIA WILL KEEP DRY WEATHER OVER THE REGION OVER THE NEXT SEVERAL DAYS. MOST OF EASTERN NEW YORK AND WESTERN NEW ENGLAND HAS NOT RECEIVED MEASURABLE RAINFALL IN ABOUT A WEEK. HIGH TEMPERATURES WILL BE COOLER TODAY COMPARED TO THE PREVIOUS TWO DAYS...BUT MINIMUM RH VALUES IN THE AFTERNOON WILL BE MAINLY IN THE 30 TO 40 PERCENT RANGE WITH SOME UPPER 20S ACROSS THE LAKE GEORGE REGION...SOUTHERN VERMONT AND THE BERKSHIRES. EAST OR SOUTHEAST WINDS OF 10 TO 15 MPH WILL BE COMMON WITH GUSTS TO ABOUT 20 MPH. RELATIVE HUMIDITY LEVELS WILL RECOVER TO BETWEEN 80 AND 100 PERCENT MONDAY MORNING...THEN LOWER TO 25 TO 40 PERCENT IN THE AFTERNOON. EXPECT THE WINDS TO GO LIGHT TO CALM SUNDAY NIGHT...AND BE LIGHT FROM THE SOUTHEAST AT 5 TO 10 MPH ON MONDAY. THERE HAVE BEEN MANY BRUSH FIRES ACROSS THE REGION THE PAST FEW DAYS WITH THE MOST NOTABLE ONE TAKING PLACE DOWN IN CENTRAL ULSTER COUNTY IN MINNEWASKA PARK. && .HYDROLOGY... DRY WEATHER AND ABOVE NORMAL TEMPERATURES ARE FORECAST OVER THE NEXT SEVERAL DAYS. THIS WILL RESULT IN CONTINUED SNOWMELT FROM AREAS IN THE ADIRONDACKS WHERE SIGNIFICANT SNOW PACK STILL REMAINS WITH SNOW LIQUID EQUIVALENTS OF THREE TO ISOLATED TEN INCH AMOUNTS. WATER STORED IN SCHROON...BRANT...AND THE GREAT SACANDAGA LAKES HAS RESULTED IN CONTINUED FLOODING ALONG THE SCHROON RIVER FROM SCHROON LAKE TO THE HUDSON RIVER...AND ALONG THE HUDSON RIVER FROM GLENS FALLS TO STILLWATER...INCLUDING THE STILLWATER FLATS. THE HUDSON WILL ALSO BE VERY CLOSE TO FLOOD AT MECHANICVILLE. EAST CANADA CREEK WILL BE NEAR BANKFULL AND WEST CANADA CREEK WILL GET VERY CLOSE TO BANKFULL FROM HINCKLEY DOWNSTREAM TO THE MOHAWK RIVER. SNOW MELT IN THE SOUTHERN GREEN MOUNTAINS HAS BOOSTED RIVER FLOWS ON THE BATTENKILL...WALLOOMSAC...WILLIAMS...SAXTONS...WEST...AND DEERFIELD RIVERS BUT THOSE RIVERS WILL REMAIN BELOW FLOOD. LITTLE RAINFALL IS EXPECTED OVER THE NEXT 5 DAYS WITH A DRY AIR MASS HOLDING OVER THE EAST COAST. PLEASE REFER TO THE LATEST FLOOD STATEMENTS AND THE AHPS GRAPHICS ON THE WEBSITE FOR CURRENT DETAILS ON SPECIFIC RIVERS AND WARNINGS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...BGM SHORT TERM...WASULA LONG TERM...IAA AVIATION...BGM FIRE WEATHER...WASULA HYDROLOGY...WASULA/RCK WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 242 PM CDT SUN APR 20 2008 .DISCUSSION... DAYS 1-2... WINDS AND TEMPERATURES WILL CONTINUE TO BE THE MAIN FORECAST CONCERNS. 12Z MAPS CONTINUE TO DIG THE NEXT UPPER TROUGH DIGGING INTO THE WESTERN CONUS, WITH A 110 KT JET ON THE BACKSIDE OF IT AND 140 M HEIGHT FALLS ACROSS NV. AT 700 AND 850MB, WARM TEMPS OF 9 C AND 21 C RESPECTIVELY HAVE MOVED UP INTO WESTERN KS. AT THE SFC, THERE WAS A DECENT PRESSURE GRADIENT WITH THE LOW OVER EASTERN WY, AND SOUTHERLY WINDS WERE BRINGING UP DEWPOINTS OF 50 PLUS CLOSE TO THE RED RIVER. THE TRULY RICH MOISTURE WAS STILL DOWN OVER CENTRAL KS. EVEN WITH THE TIGHT GRADIENT, WINDS ARE NOT QUITE AS HIGH AS EXPECTED THUS FAR. THE NAM AND RUC ARE ADVERTISING A SURGE OF 25 PLUS KTS AROUND 21Z, BUT AM ON THE FENCE ABOUT KEEPING THE ADVISORY. TONIGHT, A SHORTWAVE WILL EJECT OFF THE MAIN TROUGH IN THE WEST AND MOVE INTO THE NORTHERN PLAINS. THIS SHOULD SHIFT THE SFC TROUGH EASTWARD AND PUSH A COLD FRONT DOWN INTO THE CWA BY EARLY MORNING. WITH NOT MUCH MOISTURE TONIGHT, DON`T THINK THAT WE`LL SEE ANY PRECIP ALONG THE FRONT. WINDS WILL SHIFT AROUND TO THE NORTH AND WE SHOULD GET SOME COOLER AIR FILTERING IN TOWARDS MORNING. KEPT LOWS IN THE 40S IN THE NORTHWEST TO THE 50S IN THE SOUTHEAST. SOUTHWESTERLY FLOW ALOFT WILL CONTINUE INTO MONDAY, WITH THE SFC LOW RE-DEVELOPING JUST SOUTH OF EHA. THE FRONT SHOULD BE SOMEWHERE NEAR THE KS/OK BORDER, AND NORTHEASTERLY WINDS WILL BRING UPSLOPE. 850MB TEMPS ARE ONLY SLIGHTLY COOLER, AND WITH SUNSHINE, WE SHOULD GET BACK UP INTO THE LOW 70S IN THE NORTH, WITH UPPER 70S NEAR THE OK BORDER CLOSE TO THE FRONT. WINDS COULD PICK UP AGAIN BY MONDAY AFTERNOON, WITH THE NAM AND RUC BOTH GETTING CLOSE TO 25 KTS FOR BRIEF PERIODS. HOWEVER, IT LOOKS LIKE ANOTHER BORDERLINE CASE SO WILL HOLD OFF ON A WIND ADVISORY FOR NOW. ANOTHER SHORTWAVE TROUGH WILL MOVE OUT INTO THE PLAINS MONDAY EVENING, AND UPSLOPE FLOW SHOULD BRING SOME STRATUS NEAR OR INTO OUR SOUTHEASTERN COUNTIES. DO NOT AT THIS POINT THINK THAT WE WILL GET ANY PRECIP FROM IT, BUT CONTINUED WITH THE SILENT POPS WE HAD GOING. FLOW WILL BECOME NEAR ZONAL BY TUESDAY, WITH THE SFC HIGH BUILDING IN BEHIND THE FRONT. 850MB TEMP WILL CONTINUE TO BE IN THE TEENS, AND ANY CLOUDS SHOULD DISSIPATE BY AFTERNOON. HIGHS WILL BE IN THE 70S. DAYS 3-7... THE MAIN FORECAST DECISION CENTERS AROUND TEMPERATURES DAYS 3 AND 4...FOLLOWED BY PRECIP CHANCES THE SAME TIME FRAME. THERE APPEARS TO BE AN UPPER LEVEL TROUGH COMING THROUGH THE PLAINS ON LATE WEDNESDAY AND THROUGH THURSDAY NIGHT. OUR CWA IS ON THE BASE PORTION OF THE TROUGH SO MOST CONVECTIVE ACTION WILL BE NORTH OF US INITIALLY AND THEN TO THE EAST OF DDC`S CWA THURSDAY NIGHT. SO THE 20 POPS WEDNESDAY AFTERNOON SEEM APPROPRIATE AND INCREASING TO 30 POPS IN OUR EASTERN 2/3RDS CWA BY 12Z THURSDAY. AS THURSDAY HEAT UP INTO THE 80S...MORE CONVECTION COULD POP MAINLY IN THE EASTERN HALF OF OUR CWA DUE TO MORE MOISTURE BEING AVAILABLE. WILL ESSENTIALLY DROP ALL MENTION OF POPS BY 18Z FRIDAY AS ANY FRONT SHOULD BE SOUTHEAST OF US AND THE UPPER WAVE EAST OF WESTERN KANSAS. AFTER DAY 5...WE WILL BE BACK INTO A WESTERLY ZONAL FLOW ALOFT WITH HIGH PRESSURE AT THE SURFACE CENTERED TO OUR NORTH. SOMEWHERE ON LATE DAY 6 INTO DAY 7 (SAT-SUN)...A TROUGH LOOKS TO COME OFF THE ROCKIES AND INTO SOUTHWEST KANSAS. THIS COULD TRIGGER A FEW THUNDERSTORMS AND HAVE INTRODUCED 10 POPS FOR LATE SUNDAY INTO DAY 8 (MON). WITH THIS SYSTEM...BOUNDARIES WILL BE THE KEY FOCUS AREAS FOR CONVECTION AND WE WILL HAVE TO WAIT TO SEE IF THIS TROUGH MATERIALIZES. .AVIATION... VFR CIGS AND VSBYS THRU THE PERIOD...BUT WITH STRONG SOUTH WINDS IN THE 20 TO 30 MPH AND GUSTY RANGE THRU 01Z OR SO. WINDS WILL BECOME SOUTHEAST SHORTLY AFTER SUNSET AND SETTLE TO AROUND 15KTS FOR THE OVERNIGHT PERIOD. && .PRELIMINARY POINT TEMPS/POPS... DDC 47 71 45 72 / 0 0 10 0 GCK 44 70 44 70 / 0 0 10 0 EHA 42 75 44 73 / 0 0 10 0 LBL 44 75 45 73 / 0 0 10 0 HYS 45 70 44 71 / 0 0 10 0 P28 53 77 52 76 / 0 0 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ030-031-045-046- 064>066-078>081-087>090. RED FLAG WARNING UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR KSZ043-044-061>063-074>077-084>086. && $$ FN26/12/12 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1130 AM MDT SUN APR 20 2008 .DISCUSSION... HAVE TWEAKED FIRST PERIOD TEMP/DP/WIND GRIDS BASED ON CURRENT OBSERVATIONS AND SHORT TERM MODEL GUIDANCE. ALTHOUGH THERE IS GOOD AGREEMENT ON TEMPERATURE FORECAST DISCREPANCY STILL SHOWING UP WITH REGARD TO DEWPOINTS AND WINDS. RUC WANTS TO KEEP THE HIGHER DEWPOINTS UP AGAINST THE COLORADO/KS BORDER WHERE ITS ALSO FORECASTING LOWER WIND SPEEDS. NAM/RUC13 WANT TO PUSH THEM FURTHER EAST AND BRING THE EXPECTED HIGHER AND DRIER WINDS WITH THEM. NAM MIXING DEPTH TO 600MB OR SO VERIFIES OK WITH CURRENT SINGLE DIGIT DEWPOINTS ACROSS FAR EASTERN COLORADO. HAVE BLENDED IT WITH OTHER GUIDANCE FOR THE REST OF THE DAY. AT 17Z THE SURFACE TROUGH HAD MOVED THROUGH ALL OF FAR EASTERN COLORADO AND COUNTIES IMMEDIATELY EAST OF THE BORDER WHERE LOWER DEWPOINTS AND HIGHER/GUSTIER SOUTHWEST WINDS QUICKLY DEVELOPED. WILL CONTINUE PREVIOUS IDEA OF SLOWLY PUSHING THIS BOUNDARY EAST THROUGH THE DAY. WIND ADVISORY OVER GRAHAM AND NORTON COUNTIES MAY BE BORDERLINE BUT WILL ALLOW IT TO CONTINUE. AFTERNOON TEMPS GENERALLY 80-85. DDT && .AVIATION... FOR KGLD SKC WITH WINDS FROM THE SOUTHWEST AT 20G30KTS. AT KMCK SKC WITH WINDS FROM THE SOUTH AT 15G25KTS. BETWEEN 01-02Z BOTH SITES WILL LOSE THE GUSTS. BETWEEN 06Z-08Z A FRONT WILL MOVE INTO THE AREA SHIFTING WINDS TO THE NORTH/NORTHWEST AT 15G25KTS WITH THE INITIAL PUSH. SHORTLY THEREAFTER MAY LOSE SOME OF THE GUSTINESS. BY 17Z WINDS SHOULD VEER AROUND TO THE NORTHEAST AT 15-20KTS WITH ONLY SOME CIRRUS OVERHEAD. DDT && .FIRE WEATHER... AT 17Z RH VALUES ALREADY BELOW 15 PERCENT WEST OF A WRAY COLORADO TO GOODLAND AND LEOTI KANSAS LINE. WINDS FROM THE SOUTHWEST AT 20 TO 30 MPH. FOR THE REMAINDER OF THE DAY GUSTY SOUTHWEST WINDS AND DRIER AIR WITH RH VALUES OF 5 TO 15 PERCENT (LOWEST ACROSS COLORADO AND ADJACENT COUNTIES IN KS) WILL CONTINUE TO SPREAD EAST TOWARD GRAHAM AND NORTON COUNTIES. CURRENT FORECAST IN GOOD SHAPE AND WILL UPDATE FWFGLD PRODUCT SHORTLY. DDT && .GLD WATCHES/WARNINGS/ADVISORIES... KS...RED FLAG WARNING UNTIL 8 PM MDT /9 PM CDT/ THIS EVENING FOR KSZ001>003-013>015-027>029-041-042. WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ004-016. NE...RED FLAG WARNING UNTIL 8 PM MDT /9 PM CDT/ THIS EVENING FOR NEZ079>081. CO...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ252>254. && $$ WFO GOODLAND ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 450 PM EDT SUN APR 20 2008 .SYNOPSIS... A BROAD AREA OF LOW PRESSURE TRACKS SLOWLY ACROSS THE REGION TONIGHT AND MONDAY...AND PUSHES OFF THE NORTH CAROLINA COAST BY TUESDAY. HIGH PRESSURE BUILDS SOUTHWARD ACROSS THE MID ATLANTIC REGION WEDNESDAY INTO FRIDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... ENSEMBLE OF SHORT TERMS MODELS (RUC/NAM/GFS) HAVE HANDLED THE HEAVY PCPN BANDS ACROSS OUR FCST FAIRLY WELL UP TO THIS POINT. A MORE WIDESPREAD AXIS OF HEAVIER RAIN EARLIER THIS AM... COINCIDING WITH THE HIGHER CLOUD TOPS/DEEPER CONVECTION ORIGINATING FROM THE LOWER PTN OF THE GULF STREAM E OF THE FL PENINSULA. CLOUD TOPS HAVE WARMED (LOWERED) DURING THE AFTN HOURS AS THIS WARM CONVEYOR BELT CURVED AND SHIFTED FARTHER OFFSHORE... LIKELY DUE TO SOME DEGREE THE LOSS OF THE NOCTURNAL LLJ AND ONSET OF DIFFERENTIAL DAYTIME HEATING. RADAR TRENDS INDICATE LESS NUMEROUS CLUSTERS OF CONVECTION...HOWEVER MAIN CONCENTRATION REMAINS ALONG THE I-95 CORRIDOR. ISOLATED SVR WX WILL REMAIN POSSIBLE... AS FAVORABLE LLVL THERMODYNAMICS (THETA-E ADVECTION) COINCIDES WITH RELATIVELY STRONG MID LEVEL LAPSE RATES (7 TO 7.5 C/KM BTWN 700-500 MB)...AS THE COLD CORE/DRIER AIR ALOFT ADVECTS E-NE-N FROM THE BASE OF THE UPPER LOW AND INTO THE FCST AREA. EXPECT THE MAIN BAND(S) OF DEEPER CONVECTION TO SHIFT FROM N-S TO A MORE NW-SE ORIENTATION OVERNIGHT...WITH THE HEAVIEST RAINFALL POTENTIAL BASICALLY ALON AND S OF THE I-64 CORRIDOR. LOSS OF DIURNAL EFFECTS (DIFFERENTIAL SFC HEATING) WOULD SUGGEST A DIMINISHING TREND...HOWEVER PER RUC/NAM/GFS PROGS...DEVELOPMENT OF SUBTLE LLJ (25-30+ KTS BTWN 950-850 MB) WOULD SUPPORT FURTHER DEVELOPMENT AND PERSISTENCE OF CONVECTION. FOR NOW...HAVE OPTED NOT TO EXTEND THE CURRENT FLASH FLOOD WATCH AS BELIEVE THE REGION(S) OF HEAVIEST RAIN WILL BE SHIFTING OVERNIGHT (ALBEIT SLOWLY). && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... EXTENSIVE CLOUDS AND RAIN CHANCES CONTINUE MONDAY AS THE LOW SLOWLY PIVOTS TO THE CAROLINA COAST. KEPT HIGH (>50%) POPS IN ALL AREAS...WITH THE HEAVIEST RAIN EXPECTED OVER SC/SERN VA AND NERN NC...WHERE BEST QG FORCING AND LLVL THERMODYNAMICS ARE EXPECTED TO BE). THE PATTERN IS EXPECTED TO TRANSITION VERY SLOWLY MON NIGHT AND TUE... AS THE LOW MOVES SLOWLY SE AND EVENTUALLY OFF THE SE COAST. WHILE EXPECT RAIN CHANCES TO DIMINISH PER WEAKENING DYNAMICS...CONTINUED DEEP E TO EVENTUALLY NE FLOW WILL MAINTAIN EXTENSIVE MOISTURE ACROSS THE FCST AREA...PARTICULARLY AT LOW LEVELS. CONTINUED WITH FCST TEMPS COOLER THAN MOS GUIDANCE ON TUE IN LIGHT OF THE ANTICIPATED MAINLY CLOUDY CONDITIONS WITH SCATTERED SHOWERS. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... LATEST 12Z RUNS OF THE GFS AND ECMWF REMAIN IN FAIRLY GOOD AGREEMENT WITH THE OVERALL PATTERN...UPR LOW DRIFTS WELL OFF TO THE ESE TUE NGT/ERLY WED. HOWEVER...MODEL SNDGS SHOW PLENTY OF LOW LVL MSTR REMAINING IN PLACE AS OF 12Z WED...AND GNLY THESE AMPLIFIED FEATURES TAKE LONGER THAN MODELS THINK TO LEAVE THE REGION. HAVE UNDERCUT MOS FOR HIGHS BY ABOUT 2-3 DEGREES ON WED (MORE ON THE COAST)...AND HAVE RETAINED A 20% CHC FOR -RA IN THE SOUTHEAST. GRADUAL IMPROVEMENT THROUGH THE WEEK AS UPR RIDGE AXIS MOVES FROM THE TN/OH VALLEY THU...AND ALONG THE SPINE OF THE APPALACHIANS BY FRI. TRENDS STILL DO NOT SHOW THE RIDGE AXIS MOVING TOO FAR NEWD INTO NEW ENGLND/ERN CANADA...SO WE SHOULD HAVE DRY CONDITIONS LATER WED AFTN INTO FRI AS SFC HIGH NOSES DOWN ALONG THE EAST COAST. TEMPS RISE WELL INTO THE 70S THU/FRI EXCEPT FOR COOLER CONDITIONS ALONG THE IMMEDIATE COASTAL ZONES WITH CONTINUED EASTERLY LOW LVL FLOW. RIDGING BREAKS DOWN FRI NGT/SAT IN RESPONSE TO ANOTHER DEEP TROUGH/CUTOFF LOW MVG INTO THE GRT LAKES. HAVE BROADBRUSHED ENTIRE AREA W/ 30% POPS FOR SHWRS/TSTMS SAT. KEEPING SUNDAY DRY AT THIS PT AS FRONT MOVES SE AND OFF THE COAST. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... MVFR/VFR IN BKN CIGS TDA AS SHRAS/ISLTD T PUSH ACRS FA. ONSHR LLVL FLO DVLPG ON MON...CONTG INTO TUE...PTNTTLY LEADING TO WDSPD IFR CONDS. IMPRVMNT WL BE SLO MIDWEEK AS UPR LVL LO PRES SLIDES AWAY FM RGN. && .MARINE... SCA FLAGS WILL BE IN EFFECT FOR ALL ZONES BEGINNING THIS EVENG. WINDS WILL BE SOMEWHAT MARGINAL AT TIMES TONIGHT FOR THE BAY AND SOUND...BUT WITH CURRENT OBS SHOWING GUSTS TO AT LEAST 20 KTS...WILL SIMPLIFY THE FCST AND KEEP THESE FLAGS GOING. ON COASTAL WATERS...EXPECT SEAS TO SLOWLY COME UP TO 4-5 FT LATER THIS EVENG (CURRENTLY SEAS ARE RUNNING ARND 3 FT). THEREAFTER...PERSISTENT EASTERLY FLOW MON/TUE WILL ALLOW SEAS TO BUILD SIGNIFICANTLY...ESPECIALLY ACRS NRN COASTAL WTRS. POSITION OF SFC HIGH ACRS NEW ENGLAND STILL SUGGESTS GOING WITH A BIT MORE WIND THAN MODELS ARE CURRENTLY SHOWING...MAINLY 20-25 KTS W/ GUSTS TO 30 KT AND SEAS COMING UP TO 9 FT NRN CSTL WTRS...6-8 FT ACRS SOUTH WHERE TRACK OF THE LOW MAY KEEP WINDS A BIT LOWER. EXPECT SEAS TO REMAIN ABOVE 5 FT THROUGH AT LEAST WED NGT...AND FOR NOW HAVE EXTENDED THE SCA HEADLINES THRU 22Z TUE. TIDES... TOO EARLY AT THIS POINT FOR ANY TIDAL FLOODING PRODUCTS...AT THIS PT LOOKING TO BE 1 FOOT ANOMALIES MON NGT/TUE...ESP ACRS SRN BAY/AND CSTL WTRS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR NCZ012. VA...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR VAZ063-064- 070>076-079>083-087>090-092. MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 PM EDT TUESDAY FOR ANZ650-652-654-656-658. SMALL CRAFT ADVISORY UNTIL 6 PM EDT TUESDAY FOR ANZ630>633. && $$ SYNOPSIS...BKH NEAR TERM...BKH SHORT TERM...BKH LONG TERM...LKB AVIATION...WRS MARINE...LKB md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 316 PM EDT SUN APR 20 2008 .DISCUSSION...LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW THE UPPER LEVEL FLOW CONTINUING TO BE DOMINATED BY THE CLOSED LOW OVER THE APPALACHIANS WHICH IS UNDERCUTTING A BROAD RIDGE OVER THE CENTRAL NOAM. MID-UPPER LEVEL CLOUDS WITHIN A DEFORMATION ZONE ACROSS THE UPPER PENINSULA HAVE BEEN SLOWING LIFTING NORTH LEAVING ALL OF NORTHERN MICHIGAN UNDER SUNNY OR MOSTLY SUNNY SKIES. AMPLE SUNSHINE COMBINED WITH THE LATE APRIL SUN HAVE HELPED TEMPERATURES RISE INTO THE MID TO UPPER 70S AWAY FROM THE GREAT LAKES WITH EVEN SOME REPORTS OF LOW 80S AROUND WELLSTON/PRUDENVILLE/BELLAIRE. RH LEVELS OVER THE HIGHER TERRAIN HAVENT DROPPED QUITE AS LOW AS EXPECTED YET...AND REMAIN BETWEEN 27-32F. MEANWHILE...ON THE NORTHEAST FLANK OF THE UPPER LOW...DEEP MOISTURE PLUME IS ROTATING NE TOWARDS LAKE ERIE BUT IS HAVING TROUBLE PENETRATING A VERY DRY AIRMASS ACROSS LOWER MICHIGAN. CLOUDS AND TEMPS REMAIN THE PRIMARY FORECAST CONCERNS THROUGH TOMORROW. TONIGHT...UNDERCUTTING UPPER LOW WILL SPIN TOWARDS THE MID-ATLANTIC COAST WHILE A SLIGHT INCREASE IN MID-LEVEL HEIGHTS OCCURS OVER THE GREAT LAKES. LOW-MID LEVEL MOISTURE PLUME ROTATING AROUND THE UPPER LOW WILL PIVOT NORTHWEST TOWARDS LAKE HURON AND NE LOWER/EASTERN UPPER TONIGHT. MODELS INDICATE TO VARIOUS DEGREES THAT THE MOISTURE PLUME FALLS APART AS IT REACHES NORTHERN MICHIGAN. THE GFS IS LESS AGGRESSIVE THAN THE NAM IN THIS REGARD...AND THINK THAT THE NAM IS THE BETTER WAY TO GO GIVEN THE VERY DRY AIRMASS IN PLACE. WILL INCREASE CLOUD COVER OVER EASTERN AND NORTHERN SECTIONS OF THE CWA TONIGHT...BUT WILL KEEP ONLY PARTLY CLOUDY SKIES IN THE FORECAST. LOWS GENERALLY IN THE 40S. TOMORROW...ANOTHER PLEASANT SPRING DAY IN STORE FOR NORTHERN MICHIGAN. A SMATTERING OF LOW-MID CLOUDS TO START THE MORNING WILL EVOLVE INTO A DIURNAL CU FIELD OVER INLAND AREAS FOR THE AFTERNOON. ANY CU THAT DOES DEVELOP LOOKS TO BE LIMITED BY A MID-LEVEL CAP BETWEEN 600-700MB. THIS CAP LOOKS POTENT ENOUGH TO KEEP A DRY FORECAST IN PLACE DESPITE A MORE MOIST PROFILE THAN TODAY AND LOCALIZED CONVERGENCE ALONG LAKE BREEZES ACROSS NW LOWER WITH THE PREVALENT NE FLOW. HOWEVER...IF HIGHER DEWPOINTS INTO THE UPPER 40S MATERIALIZE...THEN CHANCES FOR A SHOWER WILL INCREASE ALONG THE LAKE BREEZE. HIGHS SLIGHTLY COOLER IN THE UPPER 60S/LOW 70S AWAY FROM THE LAKES. MPC MON NIGHT THRU WED...PRIMARY FCST CONCERN REMAINS PRECIP CHANCES TUE AFTN/NIGHT ALONG WITH TEMPS. GUIDANCE REMAINS IN GOOD AGREEMENT WITH LARGE GYRE ACRS THE PACIFIC NORTHWEST OPENING UP THRU MON AFTN AS ADDITIONAL PACIFIC ENERGY BRIEFLY UNDERCUTS BLOCKING RIDGE INTO ALASKA...WITH REMNANT ENERGY SHEARING OUT THRU THE UPPER MIDWEST TUE AFTN/EVENING. ASSOCIATED SFC COLD FRONT STILL ON TRACK TO PUSH THRU THE REGION BETWEEN 00Z AND 12Z WED...WITH OBVIOUS INCREASING THREAT FOR PRECIP DURING THIS TIME. STILL APPEARS QG SUPPORT WILL SLIP NORTH OF THE REGION...THOUGH WITH DECENT MOISTURE TAP PER WIDE OPEN WESTERN GULF AND MODEST SFC-700MB CONVERGENCE ALONG INCOMING BOUNDARY...LIKELY POPS WARRANTED AT THIS TIME...IN LINE WITH PERSISTENT TREND OF OPERATIONAL AND ENSEMBLE GUIDANCE. BIGGEST QUESTION REMAINS WHAT WILL HAPPEN AHEAD OF THE FRONT...AS APPEARS DECENT HEATING LIKELY TO TAKE SHAPE IN THE THERMAL RIDGE (HIGHS UPR 60S TO MID 70S) TUE AFTN...WHILE SFC-850MB THETA-E RIDGE BUILDS INTO THE AREA. COUPLED WITH WEAKLY UPSLOPE REGIME PER BACKING OF LOW LEVEL FLOW AHEAD OF INCOMING FRONT...AS WELL AS MODEL HINTS OF ENHANCED CONVERGENCE ALONG DEVELOPING PRE-FRONTAL TROUGH...DIFFICULT TO RULE OUT SCATTERED CONVECTION FIRING ACRS THE WESTERN CWA. FCST RAOBS WITH A 72/48 PARCEL (WHICH SHOULD BE ACHIEVABLE) YIELD 200-300 J/KG MLCAPE...THOUGH ARGUABLY GUIDANCE MAY BE OVERDOING MOISTURE JUST A TAD. IN EITHER CASE...CHANCY POPS CERTAINLY WARRANTED... ESPECIALLY WITH LATEST TREND FOR GUIDANCE TO SPEED UP TIMING OF ENTIRE SYSTEM. SHOULD SEE A QUICK END TO PRECIP BY SUNRISE WED AS LOW/MID LEVEL RIDGING QUICKLY TAKE HOLD...WITH RAPID CLEARING IN THE WAKE OF FROPA WITH 1000-500MB RH FALLING OFF THE TABLE TO AROUND 25% VIA STRONG SUBSIDENCE. COOLER READINGS IN THE MID 50S TO MID 60S WARRANTED FOR WED AFTN WITH QUICK SHOT OF COLD ADVECTION (H85 TEMPS DIP TO AROUND 3-5C PER GEFS MEAN - OPERATIONAL GFS WAY TOO COOL)...THOUGH LIKELY OFFSET BY INSOLATION OUTSIDE OF PERHAPS AFTN CU GIVEN THERMAL TROUGH OVERHEAD. LATER PERIODS (WED NIGHT THRU SUN)...RATHER BLOCKY PATTERN TO PERSIST THRU THE PERIOD...WITH HIGHLY AMPLIFIED/CLOSED MID LEVEL RIDGING ACRS ALASKA FAVORING DOWNSTREAM TROUGHING OVR CENTRAL CANADA...WITH AN EXTENSION INTO THE NORTHERN CONUS. MEDIUM RANGE GUIDANCE REMAINS IN GOOD AGREEMENT WITH THIS OVERALL SETUP...THOUGH SOME DIFFERENCES REMAIN WITH DEGREE OF AMPLIFICATION OF THE WESTERN CONUS TROUGH. STILL APPEARS A NICE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGE AND ASSOCIATED SUBSIDENCE/DRYING BUILDS OVERHEAD IN THE WAKE OF FRONTAL PASSAGE. SHOULD END UP BEING A RATHER SUNNY DAY...OUTSIDE OF SOME POTENTIAL INCREASE IN JET-DRIVEN CIRRUS BY AFTN...WITH GUIDANCE NUMBERS STILL APPEARING TO BE JUST A TOUCH TOO COOL GIVEN EXPECTED INSOLATION. THEREAFTER...INCREASING PRECIP CHANCES IN ORDER FRI/SAT TIMEFRAME AS ENERGY UNDERCUTTING PACIFIC BLOCKING RIDGE AIDS IN KICKING WESTERN TROUGH EASTWARD...WITH ASSOCIATED LEE CYCLONE DEVELOPMENT/SFC FRONTOGENESIS TAKING PLACE ACRS THE PLAINS BEFORE MAKING A RUN TOWARD THE NORTHERN LAKES. POTENTIAL FOR ANOTHER QUITE WARM DAY ON FRI WITH REGION FALLING IN THE THERMAL RIDGE AHEAD OF APPROACHING FRONT...AND HAVE THUS GONE ABOVE GUIDANCE ONCE AGAIN. ALSO SOME POTENTIAL FOR THUNDER WITH INCOMING FRONT...THOUGH WILL HOLD OFF ON MENTION AT THIS TIME WITH SOME REMAINING TIMING ISSUES. LAWRENCE && .AVIATION... /ISSUED 112 PM EDT SUN APR 20 2008/ HIGH CLOUDS WILL OCCASIONALLY DRIFT ACROSS THE TAF SITES THIS AFTERNOON. DEEPER MOISTURE WRAPPING AROUND LOW PRESSURE OVER THE APPALACHIANS WILL PINWHEEL NORTHWEST TOWARDS LAKE HURON TONIGHT. SOME 6-10KFT CLOUDS MAY REACH APN TONIGHT...BUT STILL SOME UNCERTAINTY ABOUT HOW FAR WEST THESE CLOUDS WILL MAKE IT. ANY CLOUDS WILL TRY TO EXIT TOMORROW MORNING. WILL KEEP VFR CONDITIONS PREVAILING THROUGH THE TAF PERIOD. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 348 PM CDT SUN APR 20 2008 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT DECIDED TO CANCEL THE RED FLAG WARNING AS RH VALUES ARE JUST TOO HIGH TO LET IT REMAIN IN PLACE. DEWPOINTS HAVE STAYED UP AROUND 40 DEGREES WHICH GIVES RH VALUES FROM 35 TO 45 PERCENT ACROSS CENTRAL SOUTH DAKOTA. THE STRONG WINDS AND DRY FUELS THOUGH WILL ALLOW FOR VERY HIGH TO EXTREME FIRE DANGER TO REMAIN INTO THE EVENING HOURS. AS FOR THE WIND ADVISORY...CENTRAL SOUTH DAKOTA HAS BEEN IN CRITERIA OFF AND ON ALL DAY SO WILL LET THE HEADLINE GO THROUGH 00Z THIS EVENING. FOR THE AREAS IN THE JAMES VALLEY AND POINTS EAST WITHIN THE WIND ADVISORY...HAVE ALREADY CUT BACK STOP TIME TO 00Z AND WILL MAKE A LAST MINUTE DECISION WHETHER OR NOT TO CANCEL IT ENTIRELY AS THE EAST HAS NOT REALLY MADE IT TO CRITERIA TODAY. ALTHOUGH 850 MB WINDS DO INCREASE SLIGHTLY OVER THE NEXT FEW HOURS ACCORDING TO RUC. WILL MAKE A LAST MINUTE ANALYSIS BEFORE ZONE ISSUANCE. LOW CLOUDS STILL HANGING IN TOUGH ACROSS THE FAR NORTHEASTERN CWA...EAST OF THE SISSETON HILLS WILL EASTERLY FLOW HAS ALLOWED FOR MOISTURE POOLING. ALTHOUGH AS THE LATE AFTERNOON PROGRESSES INTO EVENING...STILL EXPECTING THESE CLOUDS TO SCATTER OUT. COLD FRONT HAS NOT MOVED MUCH TODAY AND REMAINS IN PLACE ACROSS THE EXTREME WESTERN DAKOTAS. MODELS HAVE SLOWED DOWN THE FRONT AND WILL APPROACH CORSON/DEWEY COUNTIES AROUND 03Z OR SO. HI RES MODELS/REFLECTIVITY SIMULATIONS/SREF DATA STILL SHOWING ISO CONVECTION DEVELOPING LATER THIS EVENING CROSS WESTERN SOUTH DAKOTA...MOVING EAST INTO THE CENTRAL PART OF THE STATE. HAVE ALTERED POPS SLIGHTLY TO REFLECT SLOWER FRONTAL PASSAGE. CAPE VALUES AROUND 500 J/KG DEVELOP ACROSS WESTERN SOUTH DAKOTA THIS EVENING AS LIS DROP JUST BELOW ZERO. AS LAPSE RATES STEEPEN SHOULD BE ENOUGH MINIMAL INSTABILITY TO SPARK ISO/SCT CONVECTION. EXPECTING SOME OF THIS ACTIVITY TO MOVE EASTWARD ACROSS THE CWA OVERNIGHT. FRONT CLEARS THE AREA FOR THE MOST PART BY 18Z TOMORROW SO HAVE TRENDED POPS DOWNWARD A BIT AFTER 18Z. A WEAK WAVE MOVES NORTHEAST ACROSS THE AREA ON TUESDAY BUT NOT LOOKING TO IMPRESSIVE. REDUCED POPS DOWN TO 15 PERCENT AS MOST ISOLATED ACTIVITY LOOKS TO BE ACROSS NORTH CENTRAL SOUTH DAKOTA AND INTO NORTH DAKOTA. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY MEDIUM RANGE MODELS ARE IN SOME AGREEMENT WITH THE EXTENDED FORECAST PERIOD AT LEAST IN THE NEAR TERM. BY LATE IN THE PERIOD A FAIR AMOUNT OF UNCERTAINTY IS APPARENT IN ENSEMBLE SPREADS. STAYED WITH THE IDEA OF THE WESTERN UNITED STATES UPPER LEVEL H5 LOW WEAKENING AND MOVING EAST. AT THE SURFACE A LOW PRESSURE SYSTEM MOVES OFF OF THE ROCKIES AND MOVES ONTO THE PLAINS THURSDAY. KEPT WITH THE GOING THUNDERSTORM FORECAST AS A GOOD MOISTURE FEED SETS UP AHEAD OF THE LOW. FRIDAY THE REGION WILL BE BETWEEN SYSTEMS AS THE MAIN SURFACE SYSTEM MOVES TOWARD THE EAST COAST. STILL A FAIR AMOUNT OF ENERGY REMAINS IN THE UPPER LEVEL H5 FLOW WITH A TROUGH MOVING EAST OF THIS AREA AND ANOTHER ONE MOVING INTO MONTANA. THIS SYSTEM MOVES THROUGH THE AREA ON THE WEEK END WITH SOME SLIGHT CHANCE OF RAIN SHOWERS. THE BEST CHANCE APPEARS TO BE NORTH OF THIS AREA BUT DID RUN A SLIGHT CHANCE ACROSS MUCH OF THE NORTHERN TIER OF THIS AREA. TEMPERATURES WERE NOT CHANGED MUCH. NEAR SEASONAL NORMALS WILL PREVAIL WHICH WAS WHAT WAS IN THE GOING GRIDS. && .AVIATION... LOW STRATUS AND FOG IS IN PLACE ALONG AND EAST OF THE SISSETON HILLS. VISIBLE SATELLITE PICTURE SHOWS IT WILL BE SLOW TO ERODE AS FLOW CONTINUES INTO THE HILLS. SOME CONVECTIVE POTENTIAL EXISTS THIS AFTERNOON AND THIS EVENING ESPECIALLY IN THE CENTRAL PART OF SOUTH DAKOTA. A LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE ACROSS THE STATE THIS EVENING AND TONIGHT. HAVE A MENTION OF CUMULONIMBUS CLOUDS IN TAFS IN CENTRAL SOUTH DAKOTA. WILL MONITOR DEVELOPMENT OF AFTERNOON CONVECTIVE POTENTIAL. WIND WILL CONTINUE TO BE A CONCERN THIS AFTERNOON INTO EARLY EVENING AS STRONG SOUTH EAST FLOW CONTINUES AHEAD OF FRONTAL SYSTEM. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR BUFFALO- CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-HYDE-JONES- LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH. MN...NONE. && $$ SHORT TERM...TMT LONG TERM...KEEFE AVIATION...KEEFE WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1204 PM CDT SUN APR 20 2008 .UPDATE...REST OF TODAY LOW CLOUDS HAVE ERODED NICELY IN AND AROUND THE JAMES RIVER VALLEY BUT LOW CLOUDS PERSISTING IN THE SISSETON HILLS AND POINTS EAST. LATEST VIS SATELLITE IMAGERY SHOWING A THINNING AND CONTINUED EROSION FROM WEST TO EAST OVER THIS AREA SO EXPECT A GRADUAL CLEARING THROUGH THE AFTERNOON. THESE CLOUDS WILL MAKE FORECAST HIGHS A CHALLENGE ACROSS THE EAST. HAVE SO FAR BROUGHT HIGHS DOWN A COUPLE DEGREES AS ETH/VVV/8D3 STILL IN THE MID/UPPER 40S AT THIS TIME. FEEL THAT ONCE CLOUDS BEGIN TO ERODE THIS AFTERNOON TEMPS WILL RISE NICELY UNDER STRONG APRIL SUN. WILL HAVE TO MONITOR CLOUD TRENDS THROUGHOUT THE EARLY AFTERNOON FOR POSSIBLE ADDITIONAL UPDATES FOR MAX TEMPS OUT EAST. WILL LET WIND ADVISORY REMAIN IN PLACE FOR THE AFTERNOON AS CENTRAL SD CONTINUES TO SEE LOW END ADVISORY CRITERIA. MBG ALONG WITH A FEW SDSU/RAWS SITES HAVE REPORTED SUSTAINED WINDS IN THE LOW 30S MPH WITH GUSTS CLOSE TO 45 MPH. THESE WINDS WILL TRANSLATE INTO THE EASTERN CWA LATER THIS AFTERNOON. MODELS SHOWING STRONGEST 850/925 MB WINDS RIGHT NOW ACROSS CENTRAL SD AND THESE WINDS WEAKEN A BIT AS THEY MOVE EAST BUT SHOULD STILL BE ABLE TO PULL CLOSE TO ADVISORY LEVEL WINDS. AS FOR THE RED FLAG WARNING...WILL OPT TO KEEP IT IN PLACE AT THIS TIME EVEN THOUGH RH VALUES WILL NOT REACH CRITERIA. DEWPOINTS RIGHT NOW EVEN A BIT HIGHER THAN FORECAST WITH PIR/MBG SITTING AT 43 RIGHT NOW. WITH THE VERY WINDY CONDITIONS IN PLACE...ALONG WITH DRY FUELS AND THE POSSIBILITY FOR CLOUD TO GROUND LIGHTNING STRIKES ACROSS CORSON/DEWEY COUNTIES LATE THIS AFTERNOON/EARLY THIS EVENING...WILL KEEP RED FLAG WARNING GOING. WILL MONITOR THROUGHOUT THE AFTERNOON AND MAY DECIDE TO CANCEL IT WITH THE AFTERNOON FORECAST PACKAGE. LATEST MODEL DATA BEGINNING TO HINT AT CONVECTION OCCURRING AFTER DARK OUT WEST SO CLOUD TO GROUND LIGHTNING MAY NOT BE MUCH OF A FACTOR DURING SUNLIGHT HOURS. COLD FRONT POSITION RIGHT NOW ACROSS EXTREME WESTERN DAKOTAS. BUFFALO AND BOWMAN SHOWED SHARP TEMP DROPS AS FRONT MOVED THROUGH. LATEST NAM/RUC SHOWS VIRTUALLY NO MOVEMENT IN COLD FRONT UNTIL LATER THIS EVENING. && .PREV DISCUSSION... .SHORT TERM...THROUGH TUESDAY MORNING. MULTIPLE WEATHER RELATED ISSUES TO DEAL WITH THIS MORNING. FIRST OFF IS MORNING FOG THAT HAS DRIFTED IN FROM MINNESOTA ON EASTERLY FLOW. THIS WILL PERSIST THROUGH MORNING HOURS BUT IS NOT EXPECTED TO HAVE A SIGNIFICANT IMPACT ON TEMPERATURES TODAY. NEXT ISSUE TO ADDRESS WILL BE MEETING WIND ADVISORY CRITERIA. LOW LEVEL JET AHEAD OF APPROACHING SYSTEM SITUATED ACROSS THE WESTERN CWA...WITH H85 WINDS OF +50KTS. THIS LOW LEVEL JET MAXIMUM WILL BEGIN TO MIX IN WESTERN COUNTIES EARLY...GIVEN BUFKIT PROFILES WITH +45KTS AT 2KFT. DURING THE DAY...JET MAXIMUM MOVES EAST...BUT WILL NOT REACH EASTERNMOST COUNTIES UNTIL VERY LATE IN THE AFTERNOON...SO THIS WONT BE A CWA WIDE EVENT. ADDRESSED ALONG WITH THESE STRONG WINDS IS THE FIRE DANGER FOR TODAY. HAVE ISSUED A RED FLAG WARNING BASED ON WINDS DESPITE MIN RH VALUES IN THE 20 TO 30 PERCENT RANGE...TAKING INTO ACCOUNT THE LACK OF GREEN UP ACROSS CENTRAL/NORTH CENTRAL SD. WILL SEE SEVERAL CHANCES FOR PRECIPITATION AS THIS SYSTEM MOVES ACROSS THE CWA. LATE THIS AFTERNOON...WESTERN COUNTIES COULD SEE A ROGUE THUNDERSTORM...WITH CAPE VALUES UP TO 300J/KG. DRY ATMOSPHERIC PROFILES SUGGEST HIGH BASE...DRY LIGHTNING/STRONG WINDS AS THREATS. THUNDERSTORMS/SHOWERS WILL BECOME MORE WIDESPREAD AS COLD FRONT MOVES ACROSS THE STATE EARLY MONDAY. SHOWERS/THUNDERSTORM THREAT CONTINUES TUESDAY AS WEAK MID LEVEL TROUGH ROTATES AROUND UPPER LOW. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY 00Z MODELS ARE IN BETTER AGREEMENT THIS MORNING. UPPER TROF ALONG THE WEST COAST PROPAGATES EAST INTO THE CENTRAL CONUS ON THURSDAY. THE GFS IS STRONGER WITH THIS SYSTEM AND ACTUALLY FORMS A CLOSED UPPER LOW OVER NORTH DAKOTA...AS OPPOSED TO THE ECMWF/CANADIAN AND THEIR OPEN AND MORE PROGRESSIVE TROFS. NONETHELESS...IT APPEARS THERE IS A FAIR CHANCE OF PCPN WEDNESDAY NIGHT INTO THURSDAY. STRONG LLJ WILL HELP TRANSPORT LLM QUICKLY NORTH. THE GFS ADVECTS SURFACE DEWPOINTS OF UP TO 60F ALL THE WAY UP INTO THE ABR CWA. HAVE A FEELING THIS IS A BIT OVERDONE...BUT 50F DEWPOINTS CERTAINLY A POSSIBILITY. ALSO BELIEVE THE HIGH GFS DEWPOINTS ARE ADVERSELY AFFECTING ITS STABILITY PROGS. HOWEVER...THAT SAID THE DYNAMICS...AVAILABLE MOISTURE AND MID LEVEL LAPSE RATES ALL SUPPORT THUNDER...AND THUS STRATIFORM PCPN WAS CHANGED OVER TO CONVECTIVE FOR WEDNESDAY NIGHT AND THURSDAY. AHEAD OF THE SYSTEM ON WEDNESDAY AND WEDNESDAY NIGHT...BROUGHT UP TEMPS AND DEWPOINTS A NOTCH TO REFLECT THE LATEST TRENDS IN BOTH THE ECMWF AND GFS. && .AVIATION... LOW STRATUS AND FOG IS IN PLACE ALONG AND EAST OF THE SISSETON HILLS. VISIBLE SATELLITE PICTURE SHOWS IT WILL BE SLOW TO ERODE AS FLOW CONTINUES INTO THE HILLS. SOME CONVECTIVE POTENTIAL EXISTS THIS AFTERNOON AND THIS EVENING ESPECIALLY IN THE CENTRAL PART OF SOUTH DAKOTA. A LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE ACROSS THE STATE THIS EVENING AND TONIGHT. HAVE A MENTION OF CUMULONIMBUS CLOUDS IN TAFS IN CENTRAL SOUTH DAKOTA. WILL MONITOR DEVELOPMENT OF AFTERNOON CONVECTIVE POTENTIAL. WIND WILL CONTINUE TO BE A CONCERN THIS AFTERNOON INTO EARLY EVENING AS STRONG SOUTH EAST FLOW CONTINUES AHEAD OF FRONTAL SYSTEM. && .FIRE WEATHER... STRONG WINDS...WARM TEMPERATURES...AND LOW HUMIDITY ARE EXPECTED ACROSS MUCH OF SOUTH DAKOTA TODAY. THESE CONDITIONS WILL BE EXACERBATED BY A LACK OF GREENUP ACROSS THE REGION SO FAR THIS SPRING. AN EXTREME FIRE DANGER THREAT WILL EXIST THROUGH THE DAY AND INTO THE EVENING HOURS ACROSS MUCH OF THE STATE. RELATIVE HUMIDITIES ARE EXPECTED TO DROP TO BETWEEN 20 TO 30 PERCENT...AND DESPITE VALUES ABOVE THE RED FLAG CRITERIA...WINDS OF 25 TO 35 MPH WITH GUSTS TO 45 MPH WILL SUPPORT EXTREME FIRE BEHAVIOR. IN ADDITION...THERE IS A VERY LOW CHANCE THAT A THUNDERSTORM OR TWO WILL DEVELOP LATE IN THE AFTERNOON. IF ANY STORMS THAT DO DEVELOP ACROSS CENTRAL/NORTH CENTRAL SD...THESE WILL PRODUCE LITTLE ACTUAL PRECIPITATION. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...RED FLAG WARNING UNTIL 10 PM CDT /9 PM MDT/ THIS EVENING FOR LOWER BAD RIVER-MISSOURI COTEAU-UPPER CHEYENNE-UPPER MISSOURI COTEAU. WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR BUFFALO- CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-HYDE-JONES- LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH. WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR BROWN-CLARK-DAY- MARSHALL-ROBERTS-SPINK. MN...NONE. && $$ UPDATE...TMT SHORT TERM...CONNELLY LONG TERM...TDK AVIATION...KEEFE WEATHER.GOV/ABERDEEN sd