Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 01/29/08

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
230 PM PST MON JAN 28 2008 .SYNOPSIS...DEPARTING UPPER LEVEL LOW PRESSURE AND RESIDUAL MOISTURE WILL CONTINUE SCATTERED SHOWERS INTO TONIGHT ALONG WITH LOCAL STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS. PARTLY CLOUDY TUESDAY UNDER WEAK HIGH PRESSURE. FAST MOVING UPPER LEVEL LOW PRESSURE WILL BRING MORE CLOUDS...LOCAL GUSTY WINDS AND A SLIGHT CHANCE OF SHOWERS WEDNESDAY. FAIR THURSDAY UNDER HIGH PRESSURE. A COUPLE OF UPPER LOWS WILL BRING MORE CLOUDS AND COOLING TOWARD THE END OF THE WEEK WITH A CHANCE OF SHOWERS LATE SATURDAY THROUGH SUNDAY. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. .SHORT TERM (TODAY-THU)...THERE WERE LOCAL HEAVY SHOWERS THIS MORNING OVER AND W OF THE MOUNTAINS BUT THEY TAPERED OFF THIS AFTERNOON. EARLY AFTERNOON ACARS SOUNDINGS SHOWED STRONG WLY WINDS ALOFT. ONSHORE GRADIENTS WITH ABOUT 12 MB SAN-TPH AND ABOUT 7 MB SAN-IPL AND THERE WERE LOCAL STRONG GUSTY WINDS ACROSS THE MOUNTAINS AND INTO THE HIGH DESERTS. SHOWERS WILL GENERALLY DECREASE IN AREAL COVERAGE THROUGH THIS EVENING AS THE UPPER LOW CONTINUES TO MOVE E AND A LITTLE DRIER NW FLOW DEVELOPS ALOFT. A FEW SHOWERS COULD LINGER W OF THE MOUNTAINS THROUGH TONIGHT...MAINLY DUE TO ISLAND EFFECTS AND UPSLOPE FLOW. ADDITIONAL RAINFALL ACCUMULATIONS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE OF THE PRECIP BUT WILL GENERALLY BE LESS THAN A QUARTER OF AN INCH WITH LESS THAN 4 INCHES OF NEW SNOW AT THE HIGHER ELEVATIONS. THE WINDS ALOFT AND STRONG ONSHORE GRADIENTS WILL CAUSE LOCAL STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS...ESPECIALLY IN SAN BERNARDINO COUNTY THROUGH THE EVENING...DECREASING LATE TONIGHT. MOST WINDS WILL BE ADVISORY STRENGTH WITH GUSTS TO 50 MPH BUT THERE WILL BE A FEW STRONGER GUSTS TO OVER 70 MPH ON THE NE SIDE OF THE SAN BERNARDINO COUNTY MOUNTAINS AND INTO THE HIGH DESERTS. WEAK RIDGING WILL BRING PARTLY CLOUDY OR FAIR SKIES TUE WITH SLIGHT WARMING. A FAST MOVING UPPER TROUGH WILL MOVE THROUGH WED BRINGING MORE CLOUDS AND COOLING WITH A SLIGHT CHANCE OF SHOWERS. THE WINDS WILL ALSO PICK UP AGAIN WED...MAINLY IN THE MOUNTAINS AND DESERTS. WEAK RIDING AND OFFSHORE FLOW WILL DEVELOP THU FOR MOSTLY CLEAR SKIES AND WARMING...ESPECIALLY W OF THE MOUNTAINS. THERE WILL BE LOCAL GUSTY WINDS THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES THU MORNING BUT THEY SHOULD MOSTLY REMAIN BELOW ADVISORY STRENGTH. && .LONG TERM (FRI-MON)...A WEAK UPPER TROUGH FRI AND THEN A STRONGER ONE SUN WILL BRING MORE CLOUDS AND COOLING INTO THE WEEKEND WITH A CHANCE OF SHOWERS LATE SAT AND SUN. DRIER NW FLOW MON. && .AVIATION... 282100Z...SHOWERS WILL CONTINUE TO MOVE ACROSS THE AREA THROUGH EARLY AFTERNOON...PRODUCING VARIABLE CIGS AND OBSCURING HIGHER TERRAIN. SHOWERS WILL DECREASE LATER THIS AFTERNOON THROUGH TONIGHT. BASES THIS AFTERNOON AROUND 3-4K FT MSL WITH LOCAL BASES 2500 FT IN SHOWERS AND ISOLATED TO 1500 FT OR LOWER IN HEAVIER SHOWERS. VSBY MOSTLY ABOVE 7SM WITH 3-5SM IN SHOWERS AND 1-2SM IN HEAVIER SHOWERS. PARTLY CLOUDY TUESDAY WITH A WEAK SYSTEM MOVING IN TUESDAY NIGHT FOR WIDELY SCATTERED SHOWERS. TUESDAY WILL HAVE AREAS OF STRATOCU BASES AT ABOUT 4000 FT WITH VSBY ABOVE 7SM. BASES LOWERING TO 2500 FT TUE NIGHT. LOCAL SURFACE WINDS WILL BE AROUND 15 TO 25 KT GUSTING TO 45 KT WITH STRONG UP AND DOWN DRAFTS AT TIMES THROUGH THIS EVENING...MAINLY OVER THE MTNS AND DESERTS. WINDS ALOFT WILL BE WEST 30-50 KT TODAY...BECOMING NORTHWEST AND WEAKENING TO LIGHT WINDS TONIGHT THROUGH TUESDAY MORNING...INCREASING AND BECOMING STRONG AGAIN TUESDAY EVENING THROUGH TUESDAY NIGHT. && .MARINE... 282100Z...NORTHWEST WINDS WILL INCREASE TUESDAY EVENING THROUGH WEDNESDAY MORNING FOR POSSIBLE SMALL CRAFT ADVISORY CONDITIONS. && .SGX WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING FOR THE SAN BERNARDINO MOUNTAINS AND DESERTS UNTIL 8 PM TONIGHT. SEE LAXNPWSGX. WIND ADVISORY FOR THE RIVERSIDE AND SAN DIEGO COUNTY MOUNTAINS UNTIL 8 PM TONIGHT. SEE LAXNPWSGX. && $$ PUBLIC...DA AVIATION...PG
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
330 AM PST SUN JAN 27 2008 .SHORT TERM... UPPER LOW IS CURRENTLY SPINNING AT 31.50/130 WHICH ANNOYINGLY IS ABOUT 100 MILES WEST OF WHERE BOTH THE NAM AND AND THE GFS INITIALIZED IT. THE OTHER MAJOR FEATURE IS A DRY SLOT WRAPPED AROUND THE LOW. THIS DRY SLOT IS NOW MOVING INTO THE CENTRAL COAST AND WILL SLOWLY WORK ITS WAY EASTWARD. AHEAD OF THE DRY SLOT LOW LEVEL MOIST INFLOW IS KEEPING A STEADY RAIN GOING. LATER THIS MORNING THE RAIN WILL TRANSITION TO A MORE SHOWERY NATURE AS THE MOISTURE PLUME MOVES AWAY AND THE COLD CORE LOW MOVES OVER. WRF BUFR SOUNDING SHOW THAT THIS IS GOING TO BE AN INTERESTING DAY. AT 22Z KSBA SHOWS AN LI OF -4 WITH 818 CAPE AND A TRIGGER TEMP OF ONLY 54 WHICH IS AS CLOSE TO AUTO-CONVECTIVE AS IT GETS AROUND HERE. EXPECT THERE WILL BE A FEW SEVERE TSTMS. BUFR SOUNDING SHOWS THE POTENTIAL FOR ALL MANOR OF SEVERE WEATHER SVR WINDS...HAIL...AND WITH VERY NICE LOW LEVEL HELICITY TORNADOES AND WATERSPOUTS ARE NOT OUT OF THE QUESTIONS. THE SEVERE WEATHER IS MOST LIKELY FROM POINT CONCEPTION TO OXNARD AS THIS IS THE MOST LIKELY TRACK OF THE UPPER LOW. STORM TOTALS FOR THIS SYSTEM WILL RUN 2 TO 4 INCHES ALONG THE COASTS WITH 3 TO 5 INCHES ALONG THE SOUTH FACING SLOPES. FAVORED LOCATIONS IN THE MOUNTAINS COULD SEE ABOUT 7 INCHES OF RAIN WITH THIS EVENT. HOWEVER...DUE TO THE SHOWERY NATURE OF THIS SYSTEM RAINFALL AMOUNTS WILL BE VERY VARIABLE THROUGHOUT THE AREA. ANY THUNDERSTORM THAT FORMS TODAY WILL LIKELY PRODUCE HIGH INTENSITY RAINFALL WHICH COULD PRODUCE A FLASH FLOOD ANYWHERE...NOT JUST THE BURN AREAS. BECAUSE OF THE SOUTH FLOW SNOW LEVELS WILL START OUT AT OR ABOVE 7000 FEET IN FACT CURRENT ACARS SHOWS THE Z LVL AROUND 9000 FEET. AS THE COLD UPPER LOW APPROACHES THE SNOW LEVEL WILL FALL TO 5000 FEET IN THE AFTERNOON AND THEN TO 4000 FEET OVERNIGHT. THE MOST SNOW WILL FALL THIS AFTERNOON. 06Z WRF SHOWS THE WINDS WINDING UP AGAIN LATER THIS MORNING AND AS A RESULT THE WIND WARNINGS/ADVISORIES HAVE BEEN EXTENDED UNTIL 300 PM. .LONG TERM... THE GFS AND EC ARE IN GOOD AGREEMENT FOR NEXT WEEK. A WEAK TROF MOVES IN WITH THE NW FLOW THAT SETS UP AFTER TODAYS UPPER LOW. THIS WILL PRODUCE SOME SHOWER ACTIVITY MONDAY MORNING...NOT MUCH IN THE WAY OF RAINFALL WITH THIS SYSTEM. LATE MONDAY AND MOST OF TUESDAY SHOULD BE DRY BUT THEN ANOTHER WEAK IMPULSE MOVES IN TUESDAY NIGHT AND WEDNESDAY MORNING. THE BEST CHANCE OF RAIN WILL BE NORTH OF POINT CONCEPTION AND ANY RAIN THAT DOES FALL WILL NOT BE THAT THREATENING. AS THE FAST NORTHWEST FLOW CONTINUES ANOTHER IMPULSE WILL ARRIVE FRIDAY AND AGAIN IT WILL MOSTLY AFFECT AREAS NORTH OF POINT CONCEPTION AND WILL NOT PRODUCE MUCH RAINFALL. TEMPS WILL REMAIN 4 TO 8 DEGREES BELOW NORMAL THROUGH THE PERIOD. && .AVIATION... 27/1130Z ONLY LOW TO MODERATE CONFIDENCE IN 12Z TAFS. LATEST SATELLITE AND RADAR DATA SHOWS MAIN RAIN BAND SHOULD EXIT THE AREA THIS MORNING. MORE CONVECTIVE ACTIVITY CAN BE EXPECTED LATER THIS MORNING AND AFTERNOON AS THE LOW CENTER MOVES OVER THE AREA. AS THE LOW CENTER MOVES OVERHEAD...WILL EXPECT A CHANCE OF SHOWERS AND THUNDERSTORMS JUST ABOUT ANYWHERE. WILL GO WITH VCSH AND VCTS FOR ALL TAF SITES LATE THIS MORNING AND AFTERNOON...WITH VCSH PREDOMINATE OVERNIGHT. CIGS AND VSBYS WILL BE ALL OVER THE PLACE RANGING FROM IFR TO MVFR. GUSTY SOUTHEAST TO EAST FLOW WILL CONTINUE FOR SITES SOUTH OF POINT CONCEPTION THROUGH THE AFTERNOON...BEFORE SWITCHING TO A SOUTH TO SOUTHWEST DIRECTION THIS EVENING. KLAX...ONLY LOW TO MODERATE CONFIDENCE IN CIG AND VSBY FORECAST THROUGH THE PERIOD. GUSTY EAST TO SOUTHEAST WINDS WILL CONTINUE THROUGH THIS AFTERNOON WITH GUSTS TO AROUND 25 KT LIKELY. WILL HAVE CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS...WARRANTING VCSH AND VCTS FORECASTS. KBUR...MODERATE CONFIDENCE IN CIG AND VSBY FORECAST THROUGH THE PERIOD. GUSTY SOUTHEASTERLY WINDS WILL CONTINUE THROUGH THE TAF PERIOD...WITH GUSTS TO AROUND 25 KT LIKELY. WILL HAVE CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS...WARRANTING VCSH AND VCTS FORECASTS. $$ .LOX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING (SEE LAXWSWLOX). HIGH WIND WARNING (SEE LAXNPWLOX). FLOOD WATCH (SEE LAXFFALOX). WIND ADVISORY (SEE LAXNPWLOX). GALE WARNING (SEE LAXCWFLOX). SMALL CRAFT ADVISORY (SEE LAXCWFLOX). HIGH RIP CURRENT RISK (SEE LAXSRFLOX). MARINE WEATHER STATEMENT (SEE LAXMWSLOX). && $$ PUBLIC...RORKE AVIATION...THOMPSON WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS CHICAGO IL
656 PM CST MON JAN 28 2008 .DISCUSSION... 310 PM CST FOCUS REMAINS ON DEEPENING TROF IN PLAINS OVERNIGHT WITH MINOR WAVES TRAVELING NE ON STRONG 60 KT LL JET AND FEEDING HEAT AND MSTR INTO THE MS VLY AND GREAT LAKES. LATEST WAVE OF RAIN SHUD BE DEPARTING TO THE EAST LATE THIS AFTN AND EVENING. NOT MUCH WAVE ACTIVITY SWINGING THRU AFTER THIS EVENING BUT AM KEEPING A MINIMAL CHANCE OF RAIN IN AREA OVERNIGHT WITH STRONG JET FEEDING MSTR INTO AREA. SFC FNT ASSOC WITH UPR TROF SWINGS ACRS MS RVR ARND DAYBREAK WHILE STILL DEEPENING...THEN INTO NE IL IN THE EARLY AFTN...THRU NW INDIANA BY SUNSET. WHILE RAIN CHANCES STILL VALID AHEAD OF COLD FRONT...MAIN ACTIVITY OF CONCERN WILL BE POST FRONTAL. HUGE PRESSURE RISES A FEW HOURS BEHIND FROPA SHUD ACCOMPANY A QUICK DROP IN DAYTIME TEMPERATURES USHERED IN BY STORM FORCE WINDS OF 45 TO 50 MPH. POST FRONTAL PCPN MAY START OFF AS A RAIN AND SNOW MIX BUT QUICKLY TURN OVER TO SNOW TUESDAY EVENING. MELTING SNOW SHUD TAKE LITTLE TIME TO FREEZE WITH THE BLAST OF COLD ARCTIC WIND...CAUSING ROADS TO BECOME SLICK VERY FAST. AN INCH OR TWO OR MAYBE 3 INCHES OF NEW SNOW ON TOP OF THIS WILL MAKE TRAVEL EVEN WORSE. THIS ADDITIONAL SNOW OF COURSE WILL BE BLOWN SIDEWAYS AND LOWERING VISIBILITY TO A QUARTER MILE OR LESS WILL BE MAKING ROAD CLEANUP IMPOSSIBLE. PRESENTLY AM LOOKING AT 2 TO 3 INCHES OF NEW SNOW NORTH OF I-88 WITH 1 TO 2 INCHES FROM I-88 SOUTH TO I-80 AND AN INCH OR LESS SOUTH OF I-80. LUCKILY THIS PCPN WILL BE OUT OF HERE QUICKLY OVERNIGHT TUES NGT BUT STILL BLOWING INTO THE MORNING HOURS WEDNESDAY. NIGHTTIME LOWS TUESDAY NIGHT WILL DROP INTO THE MINUS AND PLUS SINGLE DIGITS FROM I-80 NORTH...TO THE LOW DOUBLE DIGITS SOUTH.. WITH HIGH WINDS STILL BLOWING THRU THE NIGHT...WIND CHILLS WILL DROP INTO ADVISORY CATEGORY IN THE NORTH AT -20 TO -25F. HEADLINES WILL PROBABLY BE POSTED FOR ADVISORIES BY TMRW MRNG AND MAY EITHER BE MULTIPLE HEADLINES OR LIMITED TO A SINGLE HEADLINE TO INCORPORATE HIGH WINDS...BLINDING SNOW...AND WIND CHILLS. THIS WILL BE WINTER AT ITS WORST...THROWING EVERYTHING IT HAS AT US. WARMUP WILL BE RATHER QUICK INTO THE TEENS AND 20S FOR WEDNESDAY INTO THURSDAY AHEAD OF ANOTHER DEEPENING TROF. THIS ONE IS HEADED SOUTH OF THE AREA ACROSS THE SRN PLAINS. BROAD UPPER RIDGING OCCURS OVER THE MIDDLE OF THE CONUS THU IN RESPONSE TO NEXT TROF DROPPING FROM CA COAST INTO SOUTHERN ROCKIES. NAM AND GFS INDICATE AN AREA OF WAA PRECIPITATION BREAKING OUT ACROSS IA AND MN WED EVENING AND LIFTING INTO WI. THE WAA PATTERN WEAKENS AS IT MOVES EAST AND FOCUS SHIFTS MORE TO DEVELOPING STORM IN SOUTHERN PLAINS. WILL KEEP FORECAST DRY FOR WEDNESDAY NIGHT AND INTO THURSDAY MORNING. STILL SOME DISCREPANCY BETWEEN GFS AND ECMWF/UKMET IN TIMING AND POSITIONING OF NEXT CYCLONE. GFS HAS A TENDENCY TO MOVE THESE SYSTEMS IN TOO FAST AND WILL TREND TOWARD SLOWER ECMWF. LATEST GFS BRINGS SURFACE LOW FROM NORTHERN MS THU EVENING TO NEAR BOWLING GREEN KY AND EVENTUALLY TO NEAR TOLEDO BY MIDDAY FRIDAY. BASED ON GFS SHOULD BE AN ALL SNOW EVENT...BUT IF ECMWF IS CORRECT AND LOW TAKES A MORE WESTERLY TRACK...PRECIP COULD MIX WITH OR CHANGE TO RAIN FAR SOUTHEAST COUNTIES. LOOKS LIKE THE BEST POTENTIAL FOR HEAVY SNOW SHOULD BE ALONG AND SE OF A STREATOR TO CHICAGO LINE. LESSER AMOUNTS UP TOWARD ROCKFORD. NEXT SHORT WAVE MOVING THROUGH IN NORTHERN STREAM ON SATURDAY. NOT MUCH MOISTURE OR DYNAMIC LIFT WITH THIS ONE AND BEST CHANCE OF LIGHT SNOW SHOULD STAY NORTH OF IL. THEN BROAD RIDGE REBUILDS AS NEXT POWERFUL STORM MOVES INTO THE WEST COAST THIS WEEKEND. COULD BRING RAIN OR SNOW TO THE AREA BY MONDAY. RLB/JJA && .AVIATION... 0000 UTC TAFS THERE WILL BE SOME LIGHT RAIN THIS EVENING. THE PROFILER WIND DATA AT 500 MB SHOWS A TROUGH OVER WESTERN IOWA AT 00 UTC. THIS WILL MOVE THROUGH NORTHEAST ILLINOIS AND NORTHWEST INDIANA OVERNIGHT. THE ACARS SOUNDING AT 0039 UTC SHOWS AN INVERSION WITH 57 KNOT WIND AT 4000 FT. THERE WILL BE GUSTS TO 35 KNOTS AT SURFACE THIS EVENING. ORD AND MDW CURRENTLY HAVE 29 TO 33 KNOT GUSTS. DURING THE NIGHT THE WIND MAY DECREASE SO SOME LOW VISIBILITY HAS BEEN ADDED. WE MAY RAISE THE VISIBILITY LATER TAFS IF THE WIND REMAINS 15 TO 25 KNOTS OVERNIGHT. THE FRONT WILL MOVE THROUGH AROUND 23 UTC IN CHICAGO AND 20 UTC IN ROCKFORD. THERE WILL BE SNOW BEHIND THE FRONT AND RAIN AND SNOW MIXED AHEAD OF THE FRONT. THE WIND WILL BE AT LEAST 20 TO 25 KNOTS FROM THE NORTHWEST LATE TUESDAY. SNOW AND BLOWING SNOW IS EXPECTED AFTER 20 UTC ACROSS ROCKFORD AND 23 UTC ACROSS CHICAGO AND GARY. WE USED THE LOCAL WRF AND THE NATIONAL WRF MODELS FOR GUIDANCE. && .MARINE... 200 PM...DEEP BROAD LOW PRESSURE OVER THE DAKOTAS THIS AFTERNOON WILL MOVE NORTHEAST ACROSS ONTARIO LATE TONIGHT AND TUESDAY. A STRONG GRADIENT EXTENDS ACROSS THE WESTERN LAKES BETWEEN THIS LOW AND HIGH PRESSURE ACROSS THE MID ATLANTIC STATES...THUS GALES WILL CONTINUE THROUGH THE EVENING HRS AND BEGIN TO DIMINISH OVERNIGHT TOWARD DAWN TUESDAY. NEW LOW PRESSURE WILL DEVELOP OVER THE CENTRAL PLAINS TUESDAY MORNING...AND MOVE NORTHEAST ACROSS THE LAKES TUESDAY EVENING...AS IT RAPIDLY DEEPENS. COLD AIR WILL POUR IN BEHIND THIS SYSTEM TUESDAY NIGHT AS THE GRADIENT TIGHTENS. FOR NOW HAVE LEFT GALES TO 45 KNOTS DURING THIS PERIOD...BUT SOME WIND GUSTS TO STORM FORCE ARE CERTAINLY POSSIBLE. WINDS SLOWLY DIMINISH WEDNESDAY AS THE LOW LIFTS NORTHEAST ACROSS QUEBEC...WHILE STILL DEEPENING. A RIDGE OF HIGH PRESSURE MOVES ACROSS THE LAKES WEDNESDAY NIGHT INTO THURSDAY BEFORE ANOTHER SFC LOW MOVES NORTHEAST ACROSS THE OHIO VALLEY FRIDAY MORNING. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING UNTIL 12 PM CST WEDNESDAY FOR LMZ740>745-777-779. && $$ WFO LOT
AREA FORECAST DISCUSSION
NWS CHICAGO IL
355 AM CST SUN JAN 27 2008 .DISCUSSION... 348 AM CST WEAK HIGH PRESSURE RIDGE MOVING ACROSS NORTHERN IL EARLY THIS MORNING RESULTING IN CLEAR SKIES...LIGHT WINDS AND PLUMMETING TEMPS OVER SNOW COVER. MILDER TEMPS ON THE WAY HOWEVER...LARGE SCALE UPPER TROUGH MOVES ASHORE OUT WEST...AND LOW LEVEL FLOW BECOMES SOUTHERLY ACROSS THE PLAINS AND MISSISSIPPI VALLEY. HAVE BLENDED TOWARD COOLER MAV NUMBERS FOR MAXES ACROSS FAR NORTHERN IL THIS AFTERNOON WHERE SEVERAL INCHES OF SNOW COVER AND RATHER COLD START TO DAY WILL INFLUENCE WARMING...BUT SHOULD SEE READINGS INTO THE LOWER 40S ACROSS SOUTHERN COUNTIES WITH NEARLY FULL SUNSHINE AND LITTLE SNOW COVER. VARIOUS MODELS IN FAIRLY GOOD AGREEMENT IN LIFTING WEAK LEAD SHORT WAVE TROUGH ACROSS THE SOUTHERN ROCKIES AND INTO THE MID/UPPER MISSISSIPPI VALLEY LATE TONIGHT...ON NOSE OF 50-60 KNOT 850 HPA JET. DESPITE INITIALLY DRY LOW/MID LEVELS...FAIRLY IMPRESSIVE MOIST CONVERGENCE AND THETA-E ADVECTION SHOULD BE QUICK TO DEVELOP INITIAL BAND OF SHOWERS WHICH SHOULD RACE ACROSS AREA MONDAY MORNING. MAY SEE A DECREASE IN SHOWER COVERAGE AS LEAD WAVE RACES NORTHEAST OF AREA BY AFTERNOON...THOUGH CONTINUED STRONG LOW LEVEL WARM ADVECTION AND ANOTHER MID LEVEL SHORT WAVE APPROACHING MONDAY EVENING MAKE TIMING DIFFICULT AND SUGGEST MAINTAINING THREAT OF SCATTERED SHOWERS THROUGH PERIOD. STILL APPEARS POTENTIAL FOR ISOLATED THUNDER ESPECIALLY MONDAY NIGHT AND AHEAD OF COLD FRONT TUESDAY AS AREA COMES UNDER LEFT EXIT OF UPPER JET AND MID LEVEL LAPSE RATES AROUND 7 DEG/KM. WITH STRONG SOUTH FLOW AND WARM ADVECTION HAVE GENERALLY GONE ABOVE GUIDANCE...ESPECIALLY SOUTHERN COUNTIES WHERE ATTAINING 50 DEGREES SHOULD BE NO PROBLEM. TEMPERATURES NO EXPECTED TO FALL MUCH MONDAY NIGHT AS COLD FRONT REMAINS WEST OF FORECAST AREA...AND NARROW LOW LEVEL MOISTURE AXIS SPREADS NORTHEAST ACROSS FORECAST AREA BY TUESDAY MORNING. MODELS HAVE SLOWED COLD FRONTAL PROGRESSION JUST A BIT TUESDAY... NOT UNEXPECTED WITH UPPER TROUGH EJECTING FROM SOUTHWEST. BASIC PREMISE STILL STANDS HOWEVER...WITH MORNING MAX TEMPS THEN SHARPLY FALLING TEMPERATURES AS FRONT PUSHES EAST ACROSS FORECAST AREA DURING THE DAY. WITH LOWERING THICKNESS VALUES AND STRONG POST FRONTAL LOW LEVEL COLD ADVECTION ALSO SHOULD SEE PRECIP TYPE CHANGE FROM RAIN TO SNOW OR SNOW SHOWERS FROM WEST TO EAST. STRONG SURFACE PRESSURE GRADIENT AND MIXED LAYER DEEPENING TO ALMOST 850 HPA IN COLD AIR TUESDAY AFTERNOON/EVENING...WINDY CONDITIONS EXPECTED WITH WRF/GFS BUFFER SOUNDINGS INDICATING POTENTIAL FOR 30-40 MPH GUSTS. SO AFTER UNSEASONABLY MILD WEATHER MONDAY AND MONDAY NIGHT...SLAP IN THE FACE TUESDAY AS WEATHER BECOMES BLUSTERY AND SHARPLY COLDER WITH RAIN CHANGING TO SNOW SHOWERS. PRECIP ENDS TUESDAY NIGHT AS UPPER TROUGH AXIS MOVES EAST AND SUBSIDENCE AND DRYING OCCUR. BRIEF SURGE OF ARCTIC AIR WITH CONTINUED WINDY CONDITIONS TUESDAY NIGHT EXPECTED TO PRODUCE SUBZERO WIND CHILLS ONCE AGAIN. WEAK HIGH PRESSURE RIDGE THEN MOVES ACROSS ARE WEDNESDAY...THOUGH LONGER RANGE GUIDANCE ALREADY DEVELOPING WARM ADVECTION ACROSS PLAINS/MISSISSIPPI VALLEY BY WEDNESDAY NIGHT AHEAD OF AMPLIFYING SOUTHERN STREAM UPPER TROUGH. GFS/ECMWF AND GEM ALL POINT TO SURFACE LOW PRESSURE DEVELOPING OVER SOUTHERN PLAINS THURSDAY... WITH INVERTED TROUGH EXTENDING NORTH INTO THE MIDWEST. SOME POTENTIAL FOR LIGHT SNOW MAINLY WEST/NORTHWEST OF FORECAST AREA AT THAT TIME WHERE BEST THERMAL ADVECTION OCCURRING IN ASSOCIATION WITH BAROCLINIC ZONE ALONG SOUTHERN PERIPHERY OF ARCTIC AIR. MORE SOLID CHANCE OF SNOW APPEARS THURSDAY NIGHT/FRIDAY...AS LONG RANGE GUIDANCE CONTINUE TO TAKE SURFACE LOW FROM SOUTHERN PLAINS FARTHER NORTHEAST INTO OHIO VALLEY...OR EVEN GREAT LAKES REGION THAN PREVIOUS RUNS. THUS HAVE BUMPED POPS JUST A BIT DURING THIS PERIOD. WILL HAVE TO WATCH TRACK OF THIS SYSTEM FOR POTENTIAL HEAVY SNOW SWATH SOMEWHERE CLOSE TO FORECAST AREA LATE IN THE WEEK. RATZER && .AVIATION... 0600 UTC TAFS THE LOW CLOUDS OVER NORTHERN ILLINOIS WILL MOVE EAST INTO LAKE MICHIGAN BY 08 UTC. THE CEILING SHOULD LIFT TO VFR BY THEN. A STABLE BOUNDARY LAYER HAS FORMED. THE ACARS AT ORD SHOWS A INVERSION AROUND 3660 FEET. THE INVERSION IS STRONG. THE WIND TO DECREASE TO LESS THAN 10 KNOTS OVERNIGHT. AS THE LOW APPROACHES FROM THE GREAT PLAINS...THE WIND WILL BECOME SOUTH LATE SUNDAY AFTERNOON AND WILL BE AROUND 10 KNOTS. && .MARINE... 355 AM CST NO SIGNIFICANT CHANGES WERE MADE TO THE MARINE FORECAST THIS MORNING...WITH A VERY ACTIVE PERIOD UPCOMING IN TERMS OF WINDS ON LAKE MICHIGAN. WEST TO NORTHWEST WINDS EARLY THIS MORNING IN THE WAKE OF A SURFACE TROUGH WHICH PASSED ACROSS LAKE MICHIGAN LAST EVENING WILL BACK TO THE SOUTHWEST TODAY AS A RIDGE OF HIGH PRESSURE MOVES EASTWARD ACROSS THE LOWER MS RIVER VALLEY. THE COMBINATION OF THE RIDGE OF HIGH PRESSURE AND FALLING PRESSURES ACROSS THE CENTRAL AND NORTHERN PLAINS WILL LEAD TO A SOUTHERLY GRADIENT BY THIS EVENING. STRONG LOW PRESSURE WILL DEVELOP ACROSS THE NORTHERN PLAINS TONIGHT INTO MONDAY WHICH WILL ALLOW FOR STRENGTHENING SOUTHERLY WINDS LATE TONIGHT INTO MONDAY. IT APPEARS AS THOUGH SOUTH GALES WILL BE POSSIBLE BY THE 12-15Z TIME FRAME MONDAY...WITH HIGH END GALES EXPECTED BY MONDAY AFTERNOON AS THE SFC PRESSURE GRADIENT CONTINUES TO STRENGTHEN. THIS LOW PRESSURE AREA IS EXPECTED TO TRACK INTO SOUTHERN ONTARIO EARLY TUESDAY WHICH MAY ALLOW GALES TO PERSIST INTO TUESDAY MORNING ACROSS THE NORTH HALF OF THE LAKE. WINDS SHOULD DIMINISH BY LATE MORNING TUESDAY...BUT THE LULL IN STRONGER WINDS WILL BE SHORT LIVED AS ANOTHER SFC LOW DEVELOPS ACROSS THE MID MS RVR VALLEY AND TRACKS NORTHEAST INTO THE EASTERN GREAT LAKES ON TUESDAY NIGHT. ARCTIC AIR WILL OVERSPREAD THE REGION LATE TUESDAY AFTERNOON INTO TUESDAY NIGHT BEHIND THIS SYSTEM...WHICH SHOULD ALLOW FOR A PERIOD OF WEST GALES FROM LATE TUESDAY AFTERNOON THROUGH EARLY WEDNESDAY. FREEZING SPRAY WILL LIKELY BECOME A CONCERN AGAIN LATE TUESDAY NIGHT...AND CONTINUING INTO WEDNESDAY. WINDS AND WAVES SHOULD SUBSIDE RATHER QUICKLY WEDNESDAY NIGHT AS A SURFACE HIGH SETTLES ACROSS THE WESTERN GREAT LAKES. IN TERMS OF HEADLINES...WILL MAINTAIN GALE WATCH FOR THE NEARSHORE AND OPEN WATERS GIVEN ONSET OF GALES EXPECTED AFTER 12Z MONDAY. MARSILI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR LMZ740>745-777-779. && $$ WFO LOT
AREA FORECAST DISCUSSION
NWS CHICAGO IL
348 AM CST SUN JAN 27 2008 .DISCUSSION... 348 AM CST WEAK HIGH PRESSURE RIDGE MOVING ACROSS NORTHERN IL EARLY THIS MORNING RESULTING IN CLEAR SKIES...LIGHT WINDS AND PLUMMETING TEMPS OVER SNOW COVER. MILDER TEMPS ON THE WAY HOWEVER...LARGE SCALE UPPER TROUGH MOVES ASHORE OUT WEST...AND LOW LEVEL FLOW BECOMES SOUTHERLY ACROSS THE PLAINS AND MISSISSIPPI VALLEY. HAVE BLENDED TOWARD COOLER MAV NUMBERS FOR MAXES ACROSS FAR NORTHERN IL THIS AFTERNOON WHERE SEVERAL INCHES OF SNOW COVER AND RATHER COLD START TO DAY WILL INFLUENCE WARMING...BUT SHOULD SEE READINGS INTO THE LOWER 40S ACROSS SOUTHERN COUNTIES WITH NEARLY FULL SUNSHINE AND LITTLE SNOW COVER. VARIOUS MODELS IN FAIRLY GOOD AGREEMENT IN LIFTING WEAK LEAD SHORT WAVE TROUGH ACROSS THE SOUTHERN ROCKIES AND INTO THE MID/UPPER MISSISSIPPI VALLEY LATE TONIGHT...ON NOSE OF 50-60 KNOT 850 HPA JET. DESPITE INITIALLY DRY LOW/MID LEVELS...FAIRLY IMPRESSIVE MOIST CONVERGENCE AND THETA-E ADVECTION SHOULD BE QUICK TO DEVELOP INITIAL BAND OF SHOWERS WHICH SHOULD RACE ACROSS AREA MONDAY MORNING. MAY SEE A DECREASE IN SHOWER COVERAGE AS LEAD WAVE RACES NORTHEAST OF AREA BY AFTERNOON...THOUGH CONTINUED STRONG LOW LEVEL WARM ADVECTION AND ANOTHER MID LEVEL SHORT WAVE APPROACHING MONDAY EVENING MAKE TIMING DIFFICULT AND SUGGEST MAINTAINING THREAT OF SCATTERED SHOWERS THROUGH PERIOD. STILL APPEARS POTENTIAL FOR ISOLATED THUNDER ESPECIALLY MONDAY NIGHT AND AHEAD OF COLD FRONT TUESDAY AS AREA COMES UNDER LEFT EXIT OF UPPER JET AND MID LEVEL LAPSE RATES AROUND 7 DEG/KM. WITH STRONG SOUTH FLOW AND WARM ADVECTION HAVE GENERALLY GONE ABOVE GUIDANCE...ESPECIALLY SOUTHERN COUNTIES WHERE ATTAINING 50 DEGREES SHOULD BE NO PROBLEM. TEMPERATURES NO EXPECTED TO FALL MUCH MONDAY NIGHT AS COLD FRONT REMAINS WEST OF FORECAST AREA...AND NARROW LOW LEVEL MOISTURE AXIS SPREADS NORTHEAST ACROSS FORECAST AREA BY TUESDAY MORNING. MODELS HAVE SLOWED COLD FRONTAL PROGRESSION JUST A BIT TUESDAY... NOT UNEXPECTED WITH UPPER TROUGH EJECTING FROM SOUTHWEST. BASIC PREMISE STILL STANDS HOWEVER...WITH MORNING MAX TEMPS THEN SHARPLY FALLING TEMPERATURES AS FRONT PUSHES EAST ACROSS FORECAST AREA DURING THE DAY. WITH LOWERING THICKNESS VALUES AND STRONG POST FRONTAL LOW LEVEL COLD ADVECTION ALSO SHOULD SEE PRECIP TYPE CHANGE FROM RAIN TO SNOW OR SNOW SHOWERS FROM WEST TO EAST. STRONG SURFACE PRESSURE GRADIENT AND MIXED LAYER DEEPENING TO ALMOST 850 HPA IN COLD AIR TUESDAY AFTERNOON/EVENING...WINDY CONDITIONS EXPECTED WITH WRF/GFS BUFFER SOUNDINGS INDICATING POTENTIAL FOR 30-40 MPH GUSTS. SO AFTER UNSEASONABLY MILD WEATHER MONDAY AND MONDAY NIGHT...SLAP IN THE FACE TUESDAY AS WEATHER BECOMES BLUSTERY AND SHARPLY COLDER WITH RAIN CHANGING TO SNOW SHOWERS. PRECIP ENDS TUESDAY NIGHT AS UPPER TROUGH AXIS MOVES EAST AND SUBSIDENCE AND DRYING OCCUR. BRIEF SURGE OF ARCTIC AIR WITH CONTINUED WINDY CONDITIONS TUESDAY NIGHT EXPECTED TO PRODUCE SUBZERO WIND CHILLS ONCE AGAIN. WEAK HIGH PRESSURE RIDGE THEN MOVES ACROSS ARE WEDNESDAY...THOUGH LONGER RANGE GUIDANCE ALREADY DEVELOPING WARM ADVECTION ACROSS PLAINS/MISSISSIPPI VALLEY BY WEDNESDAY NIGHT AHEAD OF AMPLIFYING SOUTHERN STREAM UPPER TROUGH. GFS/ECMWF AND GEM ALL POINT TO SURFACE LOW PRESSURE DEVELOPING OVER SOUTHERN PLAINS THURSDAY... WITH INVERTED TROUGH EXTENDING NORTH INTO THE MIDWEST. SOME POTENTIAL FOR LIGHT SNOW MAINLY WEST/NORTHWEST OF FORECAST AREA AT THAT TIME WHERE BEST THERMAL ADVECTION OCCURRING IN ASSOCIATION WITH BAROCLINIC ZONE ALONG SOUTHERN PERIPHERY OF ARCTIC AIR. MORE SOLID CHANCE OF SNOW APPEARS THURSDAY NIGHT/FRIDAY...AS LONG RANGE GUIDANCE CONTINUE TO TAKE SURFACE LOW FROM SOUTHERN PLAINS FARTHER NORTHEAST INTO OHIO VALLEY...OR EVEN GREAT LAKES REGION THAN PREVIOUS RUNS. THUS HAVE BUMPED POPS JUST A BIT DURING THIS PERIOD. WILL HAVE TO WATCH TRACK OF THIS SYSTEM FOR POTENTIAL HEAVY SNOW SWATH SOMEWHERE CLOSE TO FORECAST AREA LATE IN THE WEEK. RATZER && .AVIATION... 0600 UTC TAFS THE LOW CLOUDS OVER NORTHERN ILLINOIS WILL MOVE EAST INTO LAKE MICHIGAN BY 08 UTC. THE CEILING SHOULD LIFT TO VFR BY THEN. A STABLE BOUNDARY LAYER HAS FORMED. THE ACARS AT ORD SHOWS A INVERSION AROUND 3660 FEET. THE INVERSION IS STRONG. THE WIND TO DECREASE TO LESS THAN 10 KNOTS OVERNIGHT. AS THE LOW APPROACHES FROM THE GREAT PLAINS...THE WIND WILL BECOME SOUTH LATE SUNDAY AFTERNOON AND WILL BE AROUND 10 KNOTS. && .MARINE... 203 PM CST WEAK LOW PRESSURE WILL MOVE ACROSS LAKE MICHIGAN THIS EVENING. A BROAD AREA OF HIGH PRESSURE WILL MOVE ACROSS THE LOWER AND MIDDLE MISSISSIPPI VALLEY TONIGHT AND SUNDAY. THE HIGH WILL MOVE TO THE EAST COAST BY MONDAY WHILE STRONG LOW PRESSURE DEVELOPS OVER THE DAKOTAS. THIS WILL SET UP A STRONG SOUTH TO SOUTHWEST FLOW ACROSS LAKE MICHIGAN MONDAY AND MONDAY NIGHT. GALE FORCE WINDS ARE LIKELY. THE LOW WILL MOVE NORTHEAST ACROSS ONTARIO AND INTO HUDSON BAY MONDAY NIGHT AND TUESDAY. THE SOUTHWEST WINDS MAY DIMINISH BELOW GALE FORCE TUESDAY BUT A STRONG COLD FRONT WILL SURGE ACROSS LAKE MICHIGAN BY TUESDAY EVENING. THIS WILL SEND ANOTHER BLAST OF ARCTIC AIR IN FROM THE NORTHWEST...POSSIBLY RESULTING IN ANOTHER ROUND OF GALE FORCE WINDS. HIGH PRESSURE WILL BUILD INTO THE MIDWEST WEDNESDAY AND WEDNESDAY NIGHT. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR LMZ740>745-777-779. && $$ WFO LOT
AREA FORECAST DISCUSSION
NWS CHICAGO IL
1055 PM CST SAT JAN 26 2008 .DISCUSSION... 746 PM CST LATEST IMAGERY FROM THE 11-3.9U CHANNEL SHOWING LLVL CLOUD DECK THAT WAS OVER S WI EARLIER THIS AFTERNOON HAS NOW CROSSED THE STATE LINE AND NOW RESIDES OVER THE NORTHERN TIER COUNTIES INCLUDING NORTHERN COOK COUNTY. EXPECT PARTLY TO MOSTLY CLOUDY SKIES TO CONTINUE THROUGH THE MID EVENING HOURS BEFORE SFC RIDGE AXIS LOCATED OVER THE MISS RIVER VALLEY SHIFTS EASTWARD. WITH CLOUD DECK IN PLACE...DECIDED TO INCREASE OVERNIGHT LOWS ACROSS THE NORTHERN TIER COUNTIES A DEGREE OR TWO AS THE ONSET OF RADIATIONAL COOLING WILL BE SLIGHTLY DELAYED AT FIRST. ONCE CLOUDS BEGIN TO CLEAR LATER TONIGHT...EXPECT SLOWLY FALLING TEMPS. AWAY FROM THESE AREAS...PRETTY MUCH LEFT GOING FORECAST AS IS WITH NO MAJOR TWEAKS. && .AVIATION... 0600 UTC TAFS THE LOW CLOUDS OVER NORTHERN ILLINOIS WILL MOVE EAST INTO LAKE MICHIGAN BY 08 UTC. THE CEILING SHOULD LIFT TO VFR BY THEN. A STABLE BOUNDARY LAYER HAS FORMED. THE ACARS AT ORD SHOWS A INVERSION AROUND 3660 FEET. THE INVERSION IS STRONG. THE WIND TO DECREASE TO LESS THAN 10 KNOTS OVERNIGHT. AS THE LOW APPROACHES FROM THE GREAT PLAINS...THE WIND WILL BECOME SOUTH LATE SUNDAY AFTERNOON AND WILL BE AROUND 10 KNOTS. && .MARINE... 203 PM CST WEAK LOW PRESSURE WILL MOVE ACROSS LAKE MICHIGAN THIS EVENING. A BROAD AREA OF HIGH PRESSURE WILL MOVE ACROSS THE LOWER AND MIDDLE MISSISSIPPI VALLEY TONIGHT AND SUNDAY. THE HIGH WILL MOVE TO THE EAST COAST BY MONDAY WHILE STRONG LOW PRESSURE DEVELOPS OVER THE DAKOTAS. THIS WILL SET UP A STRONG SOUTH TO SOUTHWEST FLOW ACROSS LAKE MICHIGAN MONDAY AND MONDAY NIGHT. GALE FORCE WINDS ARE LIKELY. THE LOW WILL MOVE NORTHEAST ACROSS ONTARIO AND INTO HUDSON BAY MONDAY NIGHT AND TUESDAY. THE SOUTHWEST WINDS MAY DIMINISH BELOW GALE FORCE TUESDAY BUT A STRONG COLD FRONT WILL SURGE ACROSS LAKE MICHIGAN BY TUESDAY EVENING. THIS WILL SEND ANOTHER BLAST OF ARCTIC AIR IN FROM THE NORTHWEST...POSSIBLY RESULTING IN ANOTHER ROUND OF GALE FORCE WINDS. HIGH PRESSURE WILL BUILD INTO THE MIDWEST WEDNESDAY AND WEDNESDAY NIGHT. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR LMZ740>745-777-779. && $$ WFO LOT
AREA FORECAST DISCUSSION...UPDATED
NWS PADUCAH KY
707 AM CST SUN JAN 27 2008 .UPDATE... GRIDS AND PUBLIC PRODUCTS UPDATED TO ACCOUNT FOR MORE WIDESPREAD DENSE FOG OVER THE SOUTHWEST HALF OF THE AREA. && .DISCUSSION... SURFACE OBSERVATIONS FROM THE PURCHASE AREA AND ALONG THE MISSISSIPPI RIVER HAVE GONE DOWN TO A HALF MILE OR LESS...SO DECIDED TO EXPAND THE ADVISORY NORTH AND WEST. ALSO TWEAKED TRENDS IN MOST ELEMENTS TO ACCOUNT FOR THE FOG/LOW CLOUD BURNING OFF SLOWLY THIS MORNING. && .AVIATION... LIFR CIGS/VSBYS ARE PREVALENT OVER MUCH OF THE SOUTHERN HALF OF THE QUAD STATE THIS MORNING...WHILE MVFR CONDITIONS PREVAILED IN THE NORTH. NORTHERN SECTIONS SHOULD BECOME VFR QUICKLY THIS MORNING OVER SOUTHERN ILLINOIS...BUT MAY TAKE MUCH OF THE MORNING TO GET THERE IN THE EVANSVILLE/OWENSBORO AREAS. FURTHER SOUTH...IFR CONDITIONS WILL LIKELY PREVAIL TIL MIDDAY. VFR CONDITIONS ARE EXPECTED THROUGHOUT THE AREA THIS AFTERNOON...AND TONIGHT. && .PREV DISCUSSION... /ISSUED 355 AM CST SUN JAN 27 2008/ DISCUSSION... MAIN CONCERN THIS MORNING IS GETTING RID OF THE PESKY LOW CLOUDS AND FOG OVER THE SOUTHERN HALF OF THE AREA...THEN ATTENTION TURNS TO THE STORM SYSTEM FOR MONDAY NIGHT AND TUESDAY. THE LOW CLOUDS THIS MORNING SEEM TO BE TRAPPED BY THE TERRAIN BORDERED BY THE OZARKS TO THE WEST AND THE SHAWNEE HILLS NORTH. MOST AREAS APPEAR TO BE JUST LOW CLOUDS WITH LIGHT FOG...BUT PORTIONS OF SOUTHEAST MISSOURI HAVE SOME DENSE FREEZING FOG. AFTER CONDUCTING A PHONE SURVEY OF SOUTHEAST MISSOURI...WILL BE ISSUING A DENSE FOG ADVISORY FOR THE SOUTHERN PORTIONS FROM RIPLEY COUNTY TO NEW MADRID COUNTY. WITH TEMPERATURES AT OR BELOW FREEZING THROUGHOUT THE AREA...MORE BLACK ICE WILL BE POSSIBLE AS WELL. SEE NO REASON FOR THE FOG/LOW CLOUDS TO GO AWAY BEFORE THE SUN GETS A CHANCE TO WORK ON IT LATER THIS MORNING. IF IT CAN BURN OFF...THERE SHOULD BE PLENTY OF SUNSHINE THROUGHOUT THE AREA THIS AFTERNOON. HAVE UNDERCUT GUIDANCE A BIT IN MOST LOCALES FOR HIGHS TODAY...ESPECIALLY IN AREAS THAT ARE GETTING A SLOW START. ALSO UNDERCUT GUIDANCE A BIT FOR LOWS TONIGHT...FIGURING ON A BETTER PERIOD OF RADIATIONAL COOLING BEFORE THE WINDS KICK UP LATE. LOOKS LIKE SOME ELEVATED LIGHT SHOWERS MAY DEVELOP THROUGHOUT THE AREA BY MIDDAY MONDAY...SO HAVE A SLIGHT CHANCE OF SHOWERS OVER ALL BUT THE KHOP AREA IN THE AFTERNOON. THIS THICK MID/UPPER LEVEL CLOUD COVER WILL ALSO LIKELY HOLD TEMPERATURES DOWN. LITTLE CHANGE TO MONDAY NIGHT AND TUESDAY. THE MODELS SEEM TO BE DELAYING THE FRONT A BIT...AND ESPECIALLY THE 00Z ECMWF HOLDS BACK THE PRECIPITATION UNTIL THE AFTERNOON AND EVENING OVER MUCH OF THE AREA. WITH THIS IN MIND...ADDED A 20-30 POP FOR SHOWERS TUESDAY EVENING. IF ENOUGH SURFACE-BASED INSTABILITY CAN DEVELOP...WIND FIELDS WOULD SUPPORT SEVERE STORMS. RIGHT NOW THAT LOOKS LIKE A BIG IF. FEW CHANGES FOR WEDNESDAY AND BEYOND. AVIATION... LOW CLOUDS HAD CREEPED BACK INTO THE AREA SATURDAY EVENING AND CONTINUE TO PLAGUE KCGI AND KPAH EARLY THIS MORNING. KEVV AND KOWB SEEM TO HAVE DODGED THE BULLET AND ARE CURRENTLY SKC. BUT AT KCGI AND KPAH...CIGS AROUND 300 FT ARE COMMON WITH VSYBS DOWN INTO THE 3-5 SM RANGE...WITH KCGI DROPPING DOWN TO 3/4SM AT 0832Z. CLOUDS SHOULD....KEY WORD HERE IS SHOULD...SLOWLY BEGIN TO MOVE SOUTH AND OUT OF THE AREA THIS MORNING. ACCORDING TO THE LATEST TAMDAR SOUNDINGS...THE CLOUDS ARE AROUND 950MB. LOOKING AT THE LATEST MODEL DATA AND TRENDS...IT APPEARS AS THOUGH 950MB WINDS SHOULD BEGIN TO USHER IN DRIER AIR TO THE AFFECTED TERMINALS LATER ON THIS MORNING. IN ADDITION...CLOUDS SHOULD BE SHALLOW ENOUGH THAT SUNSHINE MAY AID IN THEIR EROSION. $$ PUBLIC.....DRS && .PAH WATCHES/WARNINGS/ADVISORIES... KY...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR BALLARD- CALLOWAY-CARLISLE-FULTON-GRAVES-HICKMAN-MARSHALL-MCCRACKEN. MO...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR BOLLINGER- BUTLER-CAPE GIRARDEAU-MISSISSIPPI-NEW MADRID-RIPLEY-SCOTT- STODDARD-WAYNE MO. IL...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR ALEXANDER- JOHNSON-MASSAC-PULASKI-UNION IL. IN...NONE. && $$ SHORT TERM...DRS LONG TERM....DRS AVIATION...CW
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
256 PM EST MON JAN 28 2008 .SYNOPSIS... HIGH PRESSURE WILL DRIFT OFF THE COAST EARLY TUESDAY ALLOWING FOR A COLD FRONT TO MOVE THROUGH THE REGION LATE TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT FOR WEDNESDAY AND THURSDAY. THE NEXT STORM SYSTEM WILL ARRIVE THURSDAY NIGHT AND FRIDAY. HIGH PRESSURE WILL RETURN FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... WATER VAPOR LOOP SHOWS UPPER LOW MOVING NORTHEAST OVER NEW ENGLAND WATERS. MEANWHILE...RIDGING IS BUILDING IN FROM THE MIDWEST...AHEAD OF A WEST COAST TROUGH. ACARS 400-250MB WIND OBSERVATIONS REVEAL NORTHWESTERLY FLOW ALOFT ON PERIPHERY OF UPPER RIDGE. A 125-150KT JET IS EXITING THE WEST COAST TROUGH ACROSS THE ROCKIES. 11Z SURFACE ANALYSIS PLACED AN OCCLUDED CYCLONE WELL OFF OF NEW ENGLAND...WITH A SECONDARY COLD FRONT SINKING SOUTH THROUGH NEW ENGLAND...BECOMING STATIONARY ACROSS NEW YORK STATE AND WESTERN QUEBEC. A 1024MB ANTICYCLONE WAS LOCATED ACROSS THE APPALACHIANS...WITH A TROUGH IN THE LEE OF THE MOUNTAINS. START WITH CLEAR SKIES AND LIGHT WINDS AS HIGH PRESSURE ALLOWS DECOUPLING AT SUNSET. MID AND UPPER LEVEL MOISTURE WILL QUICKLY INVADE FROM THE WEST OVERNIGHT. WESTERN MOUNTAINS MAY SEE SOME LIGHT PRECIPITATION FROM BAND OF WARM ADVECTION PRECIPITATION DURING THE PRE-DAWN HOURS. TEMPERATURES WILL LIKELY FALL BELOW FREEZING AT MOST LOCATIONS OVERNIGHT...BUT WITH CLOUDS OVERSPREADING THE REGION...EXPECT SEVERAL DEGREES OF REBOUND BY THE PRE-DAWN HOURS. VERTICAL TEMPERATURE PROFILES NEAR KCBE INDICATE +6 TO +8C BETWEEN 800-900MB...THUS EXPECT PRECIPITATION TO BE LIQUID. CANNOT RULE OUT A FEW LOCATIONS MAY REMAIN NEAR FREEZING...BUT WITH SUCH LOW PROBABILITIES OF LIGHT QPF...DONT THINK ITS PRUDENT TO HAVE IN DETERMINISTIC FORECAST. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... BEST CHANCE FOR PRECIPITATION ACROSS MOST OF THE AREA WILL BE DURING THE MORNING...AS BAND OF LIGHT WARM ADVECTION PRECIPITATION MOVES NORTHEAST INTO PENNSYLVANIA. BY AFTERNOON...THE FOCUS IS WEST OF THE MOUNTAINS CLOSER TO THE DYNAMICS OF THE APPROACHING SYSTEM. HAVE THEREFORE TRIMMED POPS BACK WITH FOCUS ALONG THE APPALACHIANS. WITH A DRIER FORECAST AND WARM AIR OFF THE SURFACE...HIGH TEMPERATURE FORECAST IS WELL INTO THE 50S EAST OF THE BLUE RIDGE. TIGHTENING PRESSURE GRADIENT SHOULD ALLOW GUSTS UP TO 25 MPH. SNOWPACK ON THE WESTERN RIDGES SHOULD KEEP TEMPERATURES OUT THERE FROM RISING BEYOND 40F. AM CONCERNED THAT WHEN DEWPOINTS RISE ABOVE FREEZING DURING THE AFTERNOON...FOG MAY DEVELOP ABOVE THE SNOWPACK. STRONG CDFROPA TMRW NGT. DUE TO SFC CNVGNC...TIGHT H8 THRML PACKING AND LLJ OF 50-60 KT...A BAND OF SHRA WL ACCMPNY FROPA... MVG W TO E. THUS...CAT POPS OVNGT...BUT NOT ALL NGT. THERE/S EVEN A HINT OF INSTBLTY...PER CAPES LESS THAN 100 J/KG AND TT 40-50. HWVR...AM A LTL HESITANT AS TO HOW MUCH WND WL MIX TO SFC AS GRND COLD...AND GIVEN ITS THE DIURNAL MIN...BNDRY LYR LIKELY WL BE TOO. BIGGEST THREAT ATTM WUD BE IF SHRA CUD TAP WNDS...SPCLY INVOF FROPA. THAT WL BE AN HWO ISSUE. DUE TO THE TIMING OF THE CDFNT... NEEDED TO PLAY W/ MIN-T A LTL. FEEL TEMPS WL STAY RELATIVELY WARM THRU THE EVNG WHILE CWFA IN THE WARM SECTOR...THEN DROP PRECIPITOUSLY W/ CDFNT. THUS... PTMC HIGHLANDS AND MAYBE BLURDG ONLY LOCATIONS WHICH WL DROP BLO FRZG AFTR MIDNGT. DUE TO THERMAL PROFILES...IF THERE/S ANY LINGERING MSTR...IT WL BE A CHGOVR TO SNW. CUD BE A LTL LINGERING PCPN IN THE E ELY IN THE DAY /REPRESENTED BY CHC POPS/...OTRW CAA WL ENSUE FOR THE DAY WED. PLENTY OF WND UPSTAIRS...AND PROFILES FVRBL TO MIX IT DWN. BASED ON MDL SNDGS... APPRS TO BE ENUF FOR A STRONG WND ADVY. TOO FAR OUT FOR THAT HEADLINE...BUT APPROPRIATE FOR AN HWO MNTN AS WELL. IN ADDITION... THE UPSLOPE COMPONENT FOR SHSN WL KICK IN...THO FAST FLOW AND WLY TRAJ MEANS THAT MSTR WL BE LMTD. THUS...WL JEEP IT AT CHC POPS AND AMTS AOB 1 IN. WL ONLY GET A GLANCING BLOW FROM THE CORE OF COLD AIR. STILL...ITLL BE ENUF TO DROP MAXT 5-7DEG F FM TUE. HIPRES WL BE TRANSITORY DUE TO JET STREAM ORIENTED ACRS CONUS. WED AFTN-THU WLL BE THAT PD. OVRALL...JAN COLD LACKING...AND TEMPS WL BE AOA CLIMO. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... LOPRES TRACKS FM LWR MS VLY TO ERN GRTLKS FRI. AS W/ PRVS DAYS... ECMWF/GFS SOLNS DIFFER. UPA PTTN ACTV AND SOMEWHAT AMPLIFIED...WHICH WUD FAVOR A SLOWER EVOLUTION. TO THAT END...EURO MORE REASONABLE. WAA AHD OF SYSTM WUD SUGGEST THAT SNW WUDNT STAND MUCH OF A CHC... PTYPE EITHER RA OR FZRA. FORTUNATELY...TKNS PTTN SUGGESTS IT WL BE WARM ENUF...THO WARY OF DIURNAL CHGS/ONSET TIMES. TOO FAR OUT TO DEAL W/ SUCH SMALLER SCALE PROCESSES...WHICH WL BE PSBL. WL SPREAD PCPN EWD THU EVE...W/ THE CORE OF PCPN THU NGT-FRI. CFP BY SAT MRNG...W/ CLRG SKIES. PER USUAL THIS TIME OF YR...THERE/S THE THREAT OF COLD AIR WORKING IN PRIOR TO PCPN SHUTOFF FRI NGT... AND THUS CHGG RA TO SNW. ATTM...DONT HV THAT THREAT PASSING E OF BLURDG. BY SAT...SKIES WL BE CLRG AS HIPRES BUILDS. WL HOLD ONTO DRY WX THRU THE WKND...THO WUDNT BE SURPRISED IF ANTHR CYCLONE APPRCHS BY END OF WKND. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... WINDS QUICKLY DIMINISH DURING THE EVENING PUSH WITH HIGH PRESSURE OVER THE AREA. MID AND UPPER LEVEL MOISTURE INVADE FROM THE WEST OVERNIGHT. SOME LOWERING OF CEILINGS TOWARD MVFR MAY OCCUR AROUND DAY BREAK AND EARLY TOMORROW MORNING KIAD WESTWARD AS WARM ADVECTION PRECIPITATION SKIRTS THE AREA AND HEADS INTO PENNSYLVANIA. DRY AFTERNOON FOR THE METRO HUBS...WITH WIND GUSTS 20-25KTS POSSIBLE FROM THE SOUTHWEST AS THE PRESSURE GRADIENT TIGHTENS. CDFNT LT TUE NGT-ELY WED MRNG. MOSTLY RA AND WND W/ THIS SYSTM. MVFR TO LCL IFR FLGT RESTRICTIONS PSBL. LLWS PSBL TMRW NGT AS WNDS SVRL THSND FT ALOFT SHUD BE 30-45 KT. SIMLR GUSTS TO SFC AFTR FROPA WED. HIPRES WED AFTN-THU. A 2ND STORM SYSTEM WL AFFECT TERMINALS THU NGT-FRI. AGN...PRIMARY PTYPE RA...BUT CUD BE SOME FZRA NEAR MRB DEPENDENT UPON ONSET TIME. && .MARINE... LIGHT WINDS TONIGHT WITH THE SURFACE RIDGE OVER THE WATERS. WINDS BECOME SOUTHERLY TOMORROW AS THE HIGH MOVES OFF THE EAST COAST. WINDS INCREASE DURING THE AFTERNOON...BUT THINK COOLER WATERS WILL PREVENT THE WARMER SOUTHWEST FLOW FROM MIXING DOWN. IF IT DOES HAPPEN HOWEVER...SMALL CRAFT WIND GUSTS WILL OCCUR. WNDS WL INCREASE IN SLY CHANNELING AHD OF CDFNT TUE NGT. MDL SNDGS DEPICT 40-50 KT SVRL THSND FT OFF DECK. HWVR...WATER TEMPS WL BE COOLER THAN AIR...AND HV DOUBTS AS TO HOW MUCH OF THAT WL MIX DWN. PTTN SEEMS LIKE ENUF TO JUSTIFY SCA ATTM. WNDS WL INCR WED AS CDFNT CROSSES WATER IN THE MRNG...ALLWG BETTER MIXING TO AFFECT MARINE AREA. ATTM...WUD APPEAR AS THOUGH THERE/S THE POTENTIAL FOR GLW WED...AT LEAST IN THE MRNG. SINCE ITS 4TH PD...WL PLACE IT IN THE HWO/SYNOPSIS AND ALLW ANOTHER CYCLE OF GNDC TO COME FORTH. WNDS WL SUBSIDE WED NGT-THU AS HIPRES MVS OHD...AND THEN INCR FRI IN SLY FLOW AHD OF NXT STORM SYSTM. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM TUESDAY TO 6 AM EST WEDNESDAY FOR ANZ530>537. && $$ SYNOPSIS...HTS NEAR TERM...ROGOWSKI SHORT TERM...ROGOWSKI/HTS LONG TERM...HTS AVIATION...ROGOWSKI/HTS MARINE...ROGOWSKI/HTS
AREA FORECAST DISCUSSION...UPDATED
NWS BALTIMORE MD/WASHINGTON DC
1159 AM EST MON JAN 28 2008 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVER THE AREA TODAY. THE HIGH WILL DRIFT OFF THE COAST EARLY TUESDAY ALLOWING FOR A COLD FRONT TO MOVE THROUGH THE REGION TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT FOR WEDNESDAY AND THURSDAY. THE NEXT STORM SYSTEM WILL ARRIVE THURSDAY NIGHT AND FRIDAY. HIGH PRESSURE WILL RETURN FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED TEXT PRODUCTS TO FRESHEN UP CLOUD WORDING...NO CHANGES TO GRIDS OR DIGITAL PRODUCTS... WATER VAPOR LOOP SHOWS UPPER LOW MOVING NORTHEAST OVER NEW ENGLAND WATERS. MEANWHILE...RIDGING IS BUILDING IN FROM THE MIDWEST...AHEAD OF A WEST COAST TROUGH. ACARS 400-250MB WIND OBSERVATIONS REVEAL NORTHWESTERLY FLOW ALOFT ON PERIPHERY OF UPPER RIDGE. A 125-150KT JET IS EXITING THE WEST COAST TROUGH ACROSS THE ROCKIES. 11Z SURFACE ANALYSIS PLACED AN OCCLUDED CYCLONE WELL OFF OF NEW ENGLAND...WITH A SECONDARY COLD FRONT SINKING SOUTH THROUGH NEW ENGLAND...BECOMING STATIONARY ACROSS NEW YORK STATE AND WESTERN QUEBEC. A 1024MB ANTICYCLONE WAS LOCATED ACROSS THE APPALACHIANS...WITH A TROUGH IN THE LEE OF THE MOUNTAINS. CORRIDOR OF STRATO-CU...WHICH DEVELOPED AS SUBSIDENCE INVERSION TRAPPED A THIN LAYER OF MOISTURE LAST NIGHT...IS MOVING TO THE NORTHEAST AT 5 MPH AS RIDGING BUILDS IN FROM THE WEST. COMBINATION OF CLOUD MOVEMENT...AND DIURNAL MIXING...SHOULD END UP YIELDING A MOSTLY SUNNY AFTERNOON ACROSS EASTERN ZONES. FURTHER WEST...EXPECT SUNSHINE WITH A FEW THIN CIRRUS INVADING FROM THE OHIO VALLEY THIS AFTERNOON. AS WARM ADVECTION CONTINUES TO OCCUR...SUNNY LOCATIONS WILL SEE TEMPERATURES CLIMB NEAR OR ABOVE 50F. TEMPERATURES MAY BE A FEW DEGREES TOO OPTIMISTIC EAST OF INTERSTATE 95 IF CLOUDS HOLD INTO THE EARLY AFTERNOON. WINDS BECOME LIGHT AS HIGH PRESSURE BUILDS INTO THE REGION. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/... HIGH OVER THE AREA FOR THE 1ST PART OF NGT...MOVG OFFSHORE OVRNGT. MDLS ARE GIVING LO CHC POPS TOWARDS TUE MRNG AS A WARM FNT MOVES INTO THE AREA. I AM A TOUCH SKEPTICAL ON THE PCPN CHCS - RDG STILL LOOKS ALONG THE CST BY 12Z...SO I`LL STAY W/ OUR CURRENT FCST OF SLT CHC ALONG THE BLUE RDG BY 12Z TUE. TEMPS MON NGT GNRLY U20S/L30S. && .LONG TERM /TUESDAY THROUGH SUNDAY/... RAISED TEMPS A FEW DEGREES TUES AFTN W/ INCR PRE-FRONTAL S/RLY WINDS. EVEN W/ INCR CLOUD COVER AND INCOMING PRECIP...SR MODELS PLACING A WEAK WARM FRONT...MORE OF A WEAK SFC TROF THO A BAROCLINIC ZONE REGARDLESS...JUST SOUTH OF MASON/DIXON LINE...ALLOWING FOR HIGHS NEAR 50 ACROSS THE PIEDMONT...U40S N OF THE BNDRY. NAM/GFS KEYING IN ON AN ELONGATED BAND OF PRECIP SPREADING NE ACROSS THE CWA TUES AFTN AND OVERNIGHT. NOT A VERY STRONG SIGNAL OF WAA...SO THE ISENTROPIC ASCENT WILL BE MINIMAL AND LOWER QPFS SHOULD RESULT FROM THE BEGINNING. RISING MOTION ALONG THE SFC TROF/BNDRY WILL BE THE MAIN FORCING...AS SW/RLY WINDS RIDE ALONG THE SLOW MOVING BNDRY. OVERNIGHT...THE SFC LOW BACK ACROSS THE GREAT LAKES REGION WILL STRENGTHEN...ALONG W/ A SHARPLY DEEPENING NEGATIVELY TILTED ACROSS THE EASTERN OHIO RIVER VALLEY. THE RESULTS WILL MOST LIKELY BE A STRONGER COLD FRONT W/ A MORE NORTH/SOUTH ORIENTATION...WHICH IS MORE FAVORABLE TO SPREAD PRECIP ACROSS THE MID ATLANTIC WHEREAS THE HIGHER ELEVATIONS WOULD NORMALLY SCATTER IT OUT BEFORE MAKING IT INTO THE PIEDMONT. LOW LEVEL WINDS WILL ALSO INCR JUST AHEAD OF A BEHIND THE FRONT...W/ 20-25KT GUSTS COMMON FOR THIS EVENT. THE STRONGEST WINDS LOOK TO BE OVERNIGHT AND EARLY WED W/ THE FRONTAL PASSAGE...MAINLY BEFORE 18Z WED. ANOTHER LEE TROF OVER THE CENTRAL/SRN PLAINS WILL GEAR UP THE NEXT SYSTEM AS A 1030MB HIGH SETTLES OVER THE MID ATLANTIC WED AND THURS. THE SFC HIGH WILL BRING MAINLY CLEAR SKIES...BUT KEEP TEMPS IN THE MID/U 40S W/ A WEAK N/RLY SFC FLOW AND COOLER TEMPS RIDING DOWN INTO THE REGION. THIS FLOW WILL ALSO BE THE FOCAL POINT FOR A POSSIBLE WEAK IN-SITU DAMMING SCENARIO. ANY CAD SITU THAT DEVELOPS WOULD LIKELY BE QUICKLY ERODED AS S/RLY FLOW INCR ON FRI AFTN. GFS SLIDES THE SFC LOW ACROSS LAKE ERIE...W/ THE ECMWF FURTHER WEST ACROSS MI. THE TRACK WILL HELP DETERMINE HOW STRONG THE PRE-FRONTAL S/RLY FLOW WILL BE IN AND IF ANY FROZEN PRECIP WILL RESULT. THICKNESS SUPPORT A RA/SN MIX FOR A BRIEF PERIOD EARLY FRI W/ THE ONSET...AND MAINLY ACROSS THE WESTERN HALF OF THE CWA. RA PREDOMINANT ACROSS THE COASTAL AND PIEDMONT REGIONS FRI MRNG/AFTN. HIGH PRESSURE OVER THE EASTERN HALF OF THE U.S. FOR THE END OF THE WEEK...INTO EARLY NEXT WEEK. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... EXPECT STRATO-CU TO DISSIPATE WITH DIURNAL MIXING AS CLOUDS GRADUALLY MOVE TO THE NORTHEAST LATE THIS MORNING. TWO SYSTEMS TO WATCH...MAINLY RAINMAKERS. TUES AFTN PRECIP WILL BEGIN TO REACH THE I-95 TAF SITES...MAINLY LIGHT/INTERMTNT TILL TUES NIGHT AHEAD OF THE COLD FRONT. S/RLY WINDS WILL INCR LATE TUES AND GUST TO 20-30KT RANGE W/ THE FRONTAL PASSAGE EARLY WED. WINDS WILL STAY IN THE 15-25KT RANGE THRU WED AS THE UPPER TROF PASSES. THURS FAIRLY QUIET...AHEAD OF ANOTHER LOW PRESSURE SYSTEM ON FRI AND EXITING THE REGION EARLY SAT. HIGH PRES FOR NEXT WEEKEND. && .MARINE... NORTHWEST WINDS BECOME LIGHT LATE THIS AFTERNOON AS THE SURFACE RIDGE MOVES OVER THE WATERS. SCA COND/S LATE TUES AND THRU MUCH OF WED. GUSTY WINDS WILL CHANNEL ACROSS THE BAY LATE TUES...AHEAD OF STRONG COLD FRONT...EXPTD TO MOVE ACROSS THE BAY EARLY WED. THE NEXT COLD FRONT EARLY SAT MRNG...W/ MORE SCA COND/S POSSIBLE FRI INTO EARLY SAT. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...ABW NEAR TERM...ROGOWSKI SHORT TERM...ABW LONG TERM...GMS AVIATION...ROGOWSKI/GMS MARINE...ROGOWSKI/GMS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
949 AM EST SUN JAN 27 2008 .SYNOPSIS... AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION THIS MORNING...THEN HIGH PRESSURE WILL BUILD OVER THE AREA FOR LATER TODAY THROUGH MONDAY. THIS HIGH WILL DRIFT OFF THE MID-ATLANTIC COAST MONDAY NIGHT AND TUESDAY ALLOWING FOR THE NEXT COLD FRONT TO SLOWLY PASS THROUGH THE REGION TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT FOR WEDNESDAY AND THURSDAY. THE NEXT STORM SYSTEM WILL ARRIVE OVERNIGHT THURSDAY AND FRIDAY...BUT HIGH PRESSURE WILL RETURN FOR NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WATER VAPOR LOOP SHOWS A TROUGH MOVING OFF THE DELMARVA AS AN UPPER LOW SINKS SOUTHEAST OVER PENNSYLVANIA. RIDGING IS OCCURRING OVER THE ROCKIES AS AN UPPER LOW TROUGH APPROACHES AN UPPER LOW OFF THE CALIFORNIA COAST. ACARS 400-250MB WIND OBSERVATIONS REVEAL SPLIT FLOW OVER THE ROCKIES...WITH A WESTERLY 120-160KT JET AT THE BASE OF THE UPPER TROUGH OVER THE SOUTHEAST CONUS. 11Z SURFACE ANALYSIS PLACED A CYCLONE DEEPER THAN 1011MB WELL OFF THE DELMARVA...WITH A COLD FRONT TRAILING SOUTHWEST THROUGH CENTRAL FLORIDA. A BACKDOOR COLD FRONT HAS SAGGED THROUGH THE NORTHERN PORTION OF NEW ENGLAND...WITH A SURFACE REFLECTION TROUGH BISECTING PENNSYLVANIA FROM NORTHWEST TO SOUTHEAST. A STATIONARY BOUNDARY EXTENDED SOUTHEAST FROM SOUTH DAKOTA INTO THE TENNESSEE VALLEY. FINALLY...A 1027MB ANTICYCLONE DOMINATED THE WESTERN GULF STATES. SYSTEM DEEPENING OVER THE ATLANTIC AS UPPER TROUGH MOVES OFF THE EAST COAST. RESULTANT SUBSIDENCE AND DIURNAL MIXING ARE ALLOWING CLOUDS TO SCATTER EAST OF THE MOUNTAINS. UPSLOPE CLOUDS AND SNOW SHOWERS POSSIBLE THROUGH THE AFTERNOON...UNTIL ANTICYCLONIC FLOW DEVELOPS THIS EVENING. TEMPERATURES EXPECTED TO NEAR OR SURPASS 40F BASED ON 12Z KIAD RAOB...REMAINING IN THE 20S WITHIN THE CLOUDY UPSLOPE MOUNTAINS. NORTH-NORTHWEST WINDS GRADUALLY INCREASE THIS AFTERNOON AS PRESSURE GRADIENT INCREASES AHEAD OF BUILDING HIGH PRESSURE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE AREA OVERNIGHT. ANY UPSLOPE SNOW SHOWERS SHOULD BEGIN TO DWINDLE IN THE EVENING HOURS...AND CLOUDS WILL BEGIN TO BREAK OVER THE HIGHLANDS. ELSEWHERE...MOSTLY CLEAR SKIES ARE EXPECTED. && .LONG TERM /MONDAY THROUGH SATURDAY/... MONDAY THROUGH TUESDAY NIGHT: HIGH PRESSURE WILL BRING DRY AND SEASONABLE CONDITIONS FOR MONDAY. THIS HIGH WILL DRIFT OFF THE COAST MONDAY NIGHT AND THE NEXT COLD FRONT WILL SLOWLY APPROACH THE REGION TUESDAY BEFORE PASSING THROUGH LATER TUESDAY NIGHT. THIS FRONT WILL BRING A CHANCE FOR RAIN ACROSS MOST LOCATIONS. HOWEVER...GUIDANCE STILL INDICATES AN AREA OF LIGHT WARM ADVECTION PRECIP WELL OUT AHEAD OF THE FRONT LATE MONDAY NIGHT INTO TUESDAY MORNING MAINLY FOR LOCATIONS ACROSS NORTHERN MARYLAND AND WEST OF THE BLUE RIDGE. SURFACE TEMPS WILL BE CLOSE TO FREEZING DURING THIS TIME SO POCKETS OF FREEZING RAIN CANNOT BE RULED OUT LATE MONDAY NIGHT INTO EARLY TUESDAY MORNING ACROSS THESE LOCATIONS. MOST PRECIP WILL END QUICKLY BEHIND THE FRONT LATE TUESDAY NIGHT...BUT WITH STRONG COLD AIR ADVECTION BEHIND THE FRONT A FEW SNOW SHOWERS ARE POSSIBLE BEFORE THE DRIER AIR TAKES OVER...MAINLY ACROSS THE POTOMAC HIGHLANDS. WEDNESDAY THROUGH FRIDAY NIGHT: HIGH PRESSURE WILL BRING DRY AND SEASONABLE CONDITIONS FOR WEDNESDAY AND THURSDAY. THE NEXT STORM SYSTEM WILL AFFECT THE AREA FOR LATER THURSDAY NIGHT AND FRIDAY. THIS STORM SYSTEM WILL LIKELY TRACK UP THROUGH THE GREAT LAKES BY FRIDAY NIGHT. THIS WILL ALLOW FOR ENOUGH WARM AIR TO MAKE RAIN THE PRIMARY PTYPE ACROSS THE REGION. HOWEVER...THERE MAY BE JUST ENOUGH LOW-LEVEL COLD AIR IN PLACE FOR A WINTRY MIX IN THE FAVORED CLIMO LOCATIONS THURSDAY NIGHT INTO FRIDAY MORNING. MOST PRECIP WILL END OVERNIGHT FRIDAY BEHIND THE FRONT BUT THERE MAY BE JUST ENOUGH MOISTURE FOR A FEW SNOW SHOWERS...MAINLY ACROSS THE POTOMAC HIGHLANDS. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... BORDERLINE MVFR CEILINGS EXPECTED TO DECAY THROUGHOUT THE MORNING AS A DEEPENING CYCLONE WELL OFF THE DELMARVA BEGINS TO MOVE OUT TO SEA. NORTHWEST FLOW WILL GRADUALLY INCREASE AS THE PRESSURE GRADIENT TIGHTENS THIS AFTERNOON. VFR CONDITIONS ARE EXPECTED FOR MONDAY. THE NEXT COLD FRONT WILL BRING A CHANCE FOR MVFR/IFR CIGS AND VSBYS TUESDAY AND TUESDAY NIGHT. VFR CONDITIONS ARE EXPECTED FOR WEDNESDAY AND THURSDAY BUT GUSTY WEST-NORTHWEST WINDS ARE EXPECTED ON WEDNESDAY BEHIND THE FRONT. THE NEXT STORM SYSTEM WILL APPROACH THE TERMINALS THURSDAY NIGHT AND FRIDAY BRINGING THE CHANCE FOR IFR/SUBIFR CIGS AND VSBYS. HIGH PRESSURE WILL BRING DRIER CONDITIONS FOR SATURDAY. && .MARINE... OBSERVATIONS AND LOCAL HIGH RESOLUTION MODELS INDICATE WINDS WILL TAKE A WHILE LONGER TO INCREASE OVER THE BAY TODAY. HAVE PUSHED SMALL CRAFT ADVISORY BACK TO TONIGHT...EXCEPT IN THE MID BAY WHERE 20KT WINDS MAY DEVELOP DURING THE MID AFTERNOON NEAR TANGIER SOUND. GUSTS UP TO 20 TO 25 KT ARE LIKELY DURING THE OVERNIGHT HOURS. WINDS WILL APPROACH SCA CRITERIA MONDAY. A BETTER CHANCE FOR SCA CRITERIA IS EXPECTED TUESDAY NIGHT AND WEDNESDAY WITH ANOTHER COLD FRONTAL PASSAGE. THE NEXT STORM SYSTEM WILL APPROACH THE WATERS THURSDAY NIGHT AND FRIDAY. HIGH PRESSURE WILL RETURN FOR SATURDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 5 PM EST MONDAY FOR ANZ530>533-537. SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 5 PM EST MONDAY FOR ANZ534. && $$ SYNOPSIS...BJL NEAR TERM...ROGOWSKI SHORT TERM...NWL LONG TERM...BJL AVIATION...ROGOWSKI/BJL MARINE...ROGOWSKI/BJL
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1045 PM EST MON JAN 28 2008 .UPDATE...FIRST ROUND OF WARM ADVECTION DRIVEN PRECIP EXITING THE EASTERN THIRD OF THE CWA ATTM. AND DESPITE A VERY DRY ATMOSPHERE/ MIXED PRECIP CONCERNS TO START...ALL OBSERVATIONS REPORTING RAIN EVEN IN EASTERN UPPER MICHIGAN. A PERFECT EXAMPLE OF THE MAGNITUDE OF WARM ADVECTION OVERWHELMING THE DEGREE OF EVAPORATIVE AND DYNAMIC COOLING. SFC DEWPOINTS AT MOST OBS SITES NOW AROUND OR ABOVE 32F. SO LOOKS LIKE ANY FREEZING RAIN THREAT HAS BEEN AVERTED. MEANWHILE UPSTREAM...SATELLITE IMAGERY SHOWING STRONG MID LEVEL SHORT WAVE PUNCHING INTO SW WISCONSIN WITH PRONOUNCED MID LEVEL DRYING BEHIND. SECOND AREA OF ASSOCIATED COOLING CLOUD TOPS AND EXPANDING PRECIP PUSHING OUT OF EASTERN WISCONSIN AND ACROSS THE LAKE. FOR THE REST OF TONIGHT...MAIN FORECAST ISSUES REVOLVE AROUND CONTINUING PRECIP CHANCES/P-TYPE...AND FOG POSSIBILITIES. SATELLITE/ RADAR EXTRAPOLATION SUGGESTS UPSTREAM SHORT WAVE AND SECOND ROUND OF LIGHT PRECIP WILL TRAVERSE SW-NE THROUGH THE CWA BETWEEN NOW AND ROUGHLY 09Z...PERHAPS HANGING ON THROUGH 12Z IN EASTERN UPPER. UPSTREAM DRY SLOT FOLLOWS SUITE AND 00Z NAM FORECAST SOUNDINGS THEN SUGGEST SOME DRIZZLE POSSIBILITIES AS SATURATED LOWER LAYERS DROP WELL BELOW THE -10C LEVEL. WILL CRAFT UPDATED GRIDS/ZONE FORECASTS ACCORDINGLY. AS FAR AS P-TYPE IS CONCERNED...MOST OBS SITES ACROSS NRN LOWER MICHIGAN REPORTING DEWPOINTS >32F...AND 00Z NAM FORECAST SOUNDINGS STILL SUGGEST ALL LIQUID. ONLY EXCEPTION REMAINS IN EASTERN UPPER MICHIGAN WHERE MUCH OF THE SOUNDING TEMP PROFILE COOLS BELOW FREEZING OVERNIGHT AND SUGGESTS A RAIN/SNOW MIX POTENTIAL. FOG ISSUES...DESPITE THE RAIN AND MELTING SNOWPACK...STRONG WINDS AND POCKETS OF LINGERING LOW LEVEL DRIER AIR (AS EVIDENCED BY CLR SKY REPORTS IN SFC OBS) HAVE KEPT FOG IN CHECK. AND BELIEVE THIS WILL REMAIN THE CASE THROUGH THE NIGHT. FOG POTENTIAL ACTUALLY LOOKS BETTER ON MONDAY AS WINDS DIMINISH/HIGHER DEWPOINT AIR CONTINUES TO ADVECT INTO THE REGION AND MELTING PROCEEDS. WITH THIS IN MIND HAVE ADDED AREAS OF FOG TO THE GOING TUESDAY FORECAST. ADAM && .AVIATION...ISSUED AT 655 PM. LOW LEVEL WIND SHEAR ANTICIPATED LATER THIS EVENING AND OVERNIGHT AT PLN/TVC/APN. AREA OF LIGHT TO MODERATE RAIN SHOWERS WILL MOVE THROUGH NORTHERN LOWER MICHIGAN EARLY THIS EVENING... HEAVIEST OF THE SHOWER ACTIVITY IMPACTING PLN/APN THROUGH 03Z. HOWEVER...DRY LOW LEVEL AIR WILL KEEP CIGS MAINLY VFR THROUGH THIS TIME. ANOTHER ROUND OF RAINFALL MAY DEVELOP UPSTREAM OVER WISCONSIN AND MOVE THROUGH THE REGION BETWEEN 03Z AND 09Z...BUT WILL SEE HOW THAT GOES. IN ANY EVENT...CIGS LOWERING TO MVFR ANTICIPATED LATE THIS EVENING AND OVERNIGHT AS THE LOW LEVELS SATURATE. ON TUESDAY... LIGHT RAIN AND DRIZZLE CONDITIONS EXPECTED TO PREVAIL WHILE IFR CIGS TAKE HOLD. ADAM .DISCUSSION...ISSUED AT 345 PM. SHORT TERM (TONIGHT)...986MB SURFACE LOW OVER ND LATE THIS AFTERNOON WILL CONTINUE TO STRENGTHEN AS IT SLIDES TO A POSITION OFF THE NORTH SHORE OF LAKE SUPERIOR TUESDAY MORNING. WARM ADVECTION WITHIN BROAD SOUTHWEST LOW/MID LEVEL FLOW SPREADING CLOUDS AND SOME LIGHT PRECIPITATION ACROSS IL/IN/WI...THOUGH STILL NOT MUCH REACHING THE GROUND ACROSS WI AS PRECIPITATION STRUGGLES THROUGH DRY AIR MASS IN PLACE OVER THE WESTERN LAKES. A SECOND AREA OF PRECIPITATION STRETCHED FROM NE/EASTERN SD/WESTERN MN AHEAD OF A SHORT WAVE TROUGH COMING OUT OF CO AND FOCUSED ALONG AN AXIS OF MID LEVEL FRONTOGENESIS. ALTHOUGH F-GEN FORCING DOES NOT LOOK LIKE IT WILL IMPACT NORTHERN MI TONIGHT...COMBINATION OF PERSISTENT WARM ADVECTION AND AN ADDED BOOST FROM AFOREMENTIONED SHORT WAVE WHICH IS EXPECTED TO CROSS THE FORECAST AREA OVERNIGHT SHOULD RESULT IN AN INCREASE IN PRECIPITATION COVERAGE DURING THE LATE AFTERNOON AND THROUGH THE EVENING HOURS. NEXT ISSUE IS PRECIPITATION TYPE... TEMPERATURES HAVE WARMED QUITE NICELY ACROSS THE REGION THIS AFTERNOON...MID/UPPER 30S ACROSS EASTERN UPPER/NORTHEAST AND NORTH CENTRAL LOWER...WITH MID/UPPER 40S ALONG THE LAKE MICHIGAN SHORELINE AIDED BY DOWNSLOPE WIND COMPONENT. MODEL VERTICAL TEMPERATURE PROFILES ARE QUITE DIFFERENT TONIGHT...WITH THE GFS BEING COLDER THAN THE NAM. EARLY AFTERNOON AIRCRAFT SOUNDINGS OUT OF PLN/CIU ARE SIMILAR TO GUIDANCE 6H FORECASTS...BUT SUGGEST THAT SOMETHING IN BETWEEN IS PROBABLY MORE REFLECTIVE OF REALITY. THE MAIN CONCERN WILL BE ACROSS EASTERN UPPER WHERE COLUMN ALOFT SHOULD BE COLD ENOUGH FOR ALL SNOW...SO PRECIP TYPE WILL BE FOCUSED ON DEPTH OF SURFACE BASED WARM LAYER. BOTH NAM/GFS SUGGESTING THAT SURFACE BASED WARM LAYER WILL BE MINIMAL/NON-EXISTENT AND THAT PRECIP WILL BE ALL SNOW. PROBLEM IS THAT SURFACE TEMPERATURES IN BOTH MODELS ARE RUNNING WELL SHORT OF CURRENT OBSERVATIONS (A GOOD 4-8 DEGREES)...WITH MID/UPPER 40S TEMPERATURES FLOODING UP THROUGH THE STRAITS AND INTO AT LEAST MACKINAC COUNTY (ERY UP TO 43F AT 20Z...MCD AT 45F). LOSS OF DIURNAL HEATING AND WET BULB COOLING WILL HAVE SOME IMPACT...BUT CURRENT THINKING IS THAT BEST CHANCE FOR SNOW OR MIXED RAIN/SNOW WILL BE ACROSS NORTHERN AND PERHAPS FAR EASTERN PORTIONS OF CHIPPEWA COUNTY. GIVEN SURGE IN SURFACE TEMPERATURES THIS AFTERNOON APPEARS FREEZING RAIN THREAT ACROSS NORTHEAST LOWER WILL BE MINIMAL...ONLY REAL CONCERN IS HIGHER TERRAIN ACROSS INTERIOR NORTHERN LOWER. EXPECT PRECIPITATION TO TAPER OFF TO DRIZZLE LATE AS MID LEVEL MOISTURE GETS STRIPPED OUT IN WAKE OF SHORT WAVE TROUGH. ONSET OF PRECIPITATION MAY ALSO BRING A PERIOD OF STRONG WINDS DUE TO THE DRY LOW LEVELS. GUSTS IN EXCESS OF 40 MPH WILL BE POSSIBLE THIS EVENING. JPB REMAINDER OF THE FORECAST (TUESDAY THROUGH NEXT MONDAY)...A VERY BUSY STRETCH OF WEATHER IS EXPECTED OVER THE NEXT SEVERAL DAYS. THE MAIN FORECAST CONCERNS WILL REVOLVE AROUND THE DETAILS OF A VIGOROUS WEATHER SYSTEM MOVING ACROSS THE AREA TUESDAY NIGHT AND WEDNESDAY INCLUDING WHETHER OR NOT HEADLINES WILL BE NECESSARY. THEREAFTER...POPS WILL BE THE MAIN ISSUE AS THE PATTERN REMAINS RATHER ACTIVE. TUESDAY...RELATIVE LULL IN THE ACTION AS THE FIRST AREA OF LOW PRESSURE CONTINUES TO TRACK ACROSS ONTARIO. DO NOT BE FOOLED THOUGH AS AN ARCTIC COLD FRONT WILL BE LURKING ACROSS THE MID MISSISSIPPI VALLEY. MODEL SOUNDINGS/CROSS SECTIONS SHOW MOISTURE SHALLOWING OUT...MAINLY CONFINED TO BELOW 800 MB. THEREFORE...WILL CONTINUE WITH ONLY A CHANCE OF LIGHT RAIN AND DRIZZLE FOR MUCH OF THE DAY. HIGHS OF WELL INTO THE 30S TO AROUND 40 EXPECTED WITH SOUTH SOUTHWEST WINDS OF BETWEEN 10 AND 20 MPH. LATE TUESDAY INTO TUESDAY NIGHT...STRONG FORCING ALONG WITH ABUNDANT MOISTURE OUT AHEAD OF THE VIGOROUS COLD FRONT WILL QUICKLY OVERSPREAD THE REGION FROM THE WEST LEADING TO RAINFALL ACROSS THE ENTIRE FORECAST AREA LATE IN THE AFTERNOON. THE ARCTIC COLD FRONT THEN PLOWS ACROSS THE REGION IN THE EVENING WITH VERY STRONG COLD AIR ADVECTION BEHIND IT (850 MB TEMPERATURES PLUMMET FROM AROUND PLUS 4 C AT 00Z TUE TO BETWEEN -20 AND -25 C AT 12Z) LEADING TO FALLING TEMPERATURES LIKELY LEADING TO A RAPID FREEZE UP OF AREA ROADWAYS. MEANWHILE...A WAVE OF LOW PRESSURE MOVES UP ALONG THE FRONT WHILE RAPIDLY INTENSIFYING TO BETWEEN 975 AND 980 MB. 925 MB WINDS OF 35 TO 40 KNOTS ARE NOT EXPECTED TO HAVE TOO MUCH OF A PROBLEM MIXING DOWN WHICH WOULD LEAD TO THE POTENTIAL FOR BLIZZARD LIKE CONDITIONS DEVELOPING AT TIMES TUESDAY EVENING AND TUESDAY NIGHT (AND GALES ACROSS NEARSHORE ZONES). THEREFORE...WILL ISSUE A WINTER STORM WATCH FROM TUE EVENING THROUGH WED ACROSS ALL ZONES EXCEPT GLADWIN AND ARENAC COUNTIES FOR THE COMBINATION OF STRONG WINDS...LOW VISIBILITIES AND LOW WIND CHILLS. ACCUMULATIONS WED NIGHT ARE EXPECTED TO RANGE FROM AN INCH OR TWO SOUTHEAST TO FOUR OR FIVE INCHES ACROSS EASTERN UPPER WHERE THE BEST WRAP AROUND MOISTURE IS SHOWN. TEMPERATURES WILL PLUNGE OVERNIGHT ENDING UP BETWEEN 10 AND 15 DEGREES BY WED MORNING. WEDNESDAY...850 MB TEMPERATURES BOTTOM OUT BETWEEN -23 AND -28 C. THE MEAN SURFACE-850 MB FLOW SETTLES IN OUT OF THE WEST LEADING TO LAKE EFFECT SNOW SHOWERS. MEAN 900-700 MB RH FALLS FROM BETWEEN 70 AND 80 PERCENT IN THE MORNING TO BETWEEN 30 AND 50 PERCENT IN THE AFTERNOON. MEAN 1000-850 MB WINDS REMAIN ABOUT 30 KNOTS THROUGH THE DAY SO LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO BE PUSHED ALL THE WAY TO THE LAKE HURON SHORELINE. ACCUMULATIONS DO NOT LOOK OVERLY IMPRESSIVE AS COLD THERMAL REGIME WOULD SUPPORT SMALL SNOWFLAKE PRODUCTION SO A COUPLE OF INCHES EXPECTED IN WESTERLY FLOW FAVORED AREAS AND AN INCH OR LESS ELSEWHERE. HOWEVER...EXTENSIVE BLOWING AND DRIFTING SNOW IS EXPECTED TO CONTINUE LEADING TO POTENTIAL FOR HAZARDOUS TRAVEL CONDITIONS. TEMPERATURES WILL REMAIN NEARLY STEADY IN THE TEENS OR FALL INTO THE UPPER SINGLE DIGITS AS COLD AIR ADVECTION CONTINUES. WIND CHILLS VALUES COULD BE AS LOW AS 10 TO 15 DEGREES BELOW ZERO. WEDNESDAY NIGHT INTO THURSDAY...LAKE EFFECT IS EXPECTED TO LINGER AS 850 MB TEMPERATURES BEGIN TO STEADILY RISE BACK INTO THE -10 TO -15 C RANGE. THE FLOW IS SHOWN TO BACK FROM THE WEST INTO THE SOUTHWEST BY THURSDAY. LOWS WED NIGHT WITHIN A FEW DEGREES EITHER SIDE OF ZERO. HIGHS ON THURSDAY RANGING FROM THE UPPER TEENS TO THE MIDDLE 20S. FRIDAY THROUGH NEXT MONDAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN ENERGETIC SOUTHERN JET STREAM SENDING ENERGY NORTHWARD TOWARD THE GREAT LAKES. THERE IS THE POTENTIAL FOR MAJOR STORM SYSTEM TO AFFECT THE REGION ON FRIDAY AND AGAIN SOMETIME EARLY NEXT WEEK. IN BETWEEN...AN ALBERTA CLIPPER WILL BRING A CHANCE OF LIGHT SNOW LATE SATURDAY INTO SATURDAY NIGHT. NO ARCTIC AIR IS IN SIGHT WITH SEASONABLE TEMPERATURES EXPECTED WITH HIGHS IN THE UPPER 20S TO LOWER 30S AND LOWS IN THE TEENS. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ008-015>036. LM...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LMZ323-341-342-344>346. LH...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LHZ345>349. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1009 PM EST MON JAN 28 2008 .UPDATE...FIRST ROUND OF WARM ADVECTION DRIVEN PRECIP EXITING THE EASTERN THIRD OF THE CWA ATTM. AND DESPITE A VERY DRY ATMOSPHERE/ MIXED PRECIP CONCERNS TO START...ALL OBSERVATIONS REPORTING RAIN EVEN IN EASTERN UPPER MICHIGAN. A PERFECT EXAMPLE OF THE MAGNITUDE OF WARM ADVECTION OVERWHELMING THE DEGREE OF EVAPORATIVE AND DYNAMIC COOLING. SFC DEWPOINTS AT MOST OBS SITES NOW AROUND OR ABOVE 32F. SO LOOKS LIKE ANY FREEZING RAIN THREAT HAS BEEN AVERTED. MEANWHILE UPSTREAM...SATELLITE IMAGERY SHOWING STRONG MID LEVEL SHORT WAVE PUNCHING INTO SW WISCONSIN WITH PRONOUNCED MID LEVEL DRYING BEHIND. SECOND AREA OF ASSOCIATED COOLING CLOUD TOPS AND EXPANDING PRECIP PUSHING OUT OF EASTERN WISCONSIN AND ACROSS THE LAKE. FOR THE REST OF TONIGHT...MAIN FORECAST ISSUES REVOLVE AROUND CONTINUING PRECIP CHANCES/P-TYPE...AND FOG POSSIBILITIES. SATELLITE/ RADAR EXTRAPOLATION SUGGESTS UPSTREAM SHORT WAVE AND SECOND ROUND OF LIGHT PRECIP WILL TRAVERSE SW-NE THROUGH THE CWA BETWEEN NOW AND ROUGHLY 09Z...PERHAPS HANGING ON THROUGH 12Z IN EASTERN UPPER. UPSTREAM DRY SLOT FOLLOWS SUITE AND 00Z NAM FORECAST SOUNDINGS THEN SUGGEST SOME DRIZZLE POSSIBILITIES AS SATURATED LOWER LAYERS DROP WELL BELOW THE -10C LEVEL. WILL CRAFT UPDATED GRIDS/ZONE FORECASTS ACCORDINGLY. AS FAR AS P-TYPE IS CONCERNED...MOST OBS SITES ACROSS NRN LOWER MICHIGAN REPORTING DEWPOINTS >32F...AND 00Z NAM FORECAST SOUNDINGS STILL SUGGEST ALL LIQUID. ONLY EXCEPTION REMAINS IN EASTERN UPPER MICHIGAN WHERE MUCH OF THE SOUNDING TEMP PROFILE COOLS BELOW FREEZING OVERNIGHT AND SUGGESTS A RAIN/SNOW MIX POTENTIAL. FOG ISSUES...DESPITE THE RAIN AND MELTING SNOWPACK...STRONG WINDS AND POCKETS OF LINGERING LOW LEVEL DRIER AIR (AS EVIDENCED BY CLR SKY REPORTS IN SFC OBS) HAVE KEPT FOG IN CHECK. AND BELIEVE THIS WILL REMAIN THE CASE THROUGH THE NIGHT. FOG POTENTIAL ACTUALLY LOOKS BETTER ON MONDAY AS WINDS DIMINISH/HIGHER DEWPOINT AIR CONTINUES TO ADVECT INTO THE REGION AND MELTING PROCEEDS. WITH THIS IN MIND HAVE ADDED AREAS OF FOG TO THE GOING TUESDAY FORECAST. ADAM && .AVIATION...ISSUED AT 655 PM. LOW LEVEL WIND SHEAR ANTICIPATED LATER THIS EVENING AND OVERNIGHT AT PLN/TVC/APN. AREA OF LIGHT TO MODERATE RAIN SHOWERS WILL MOVE THROUGH NORTHERN LOWER MICHIGAN EARLY THIS EVENING... HEAVIEST OF THE SHOWER ACTIVITY IMPACTING PLN/APN THROUGH 03Z. HOWEVER...DRY LOW LEVEL AIR WILL KEEP CIGS MAINLY VFR THROUGH THIS TIME. ANOTHER ROUND OF RAINFALL MAY DEVELOP UPSTREAM OVER WISCONSIN AND MOVE THROUGH THE REGION BETWEEN 03Z AND 09Z...BUT WILL SEE HOW THAT GOES. IN ANY EVENT...CIGS LOWERING TO MVFR ANTICIPATED LATE THIS EVENING AND OVERNIGHT AS THE LOW LEVELS SATURATE. ON TUESDAY... LIGHT RAIN AND DRIZZLE CONDITIONS EXPECTED TO PREVAIL WHILE IFR CIGS TAKE HOLD. ADAM .DISCUSSION...ISSUED AT 345 PM. SHORT TERM (TONIGHT)...986MB SURFACE LOW OVER ND LATE THIS AFTERNOON WILL CONTINUE TO STRENGTHEN AS IT SLIDES TO A POSITION OFF THE NORTH SHORE OF LAKE SUPERIOR TUESDAY MORNING. WARM ADVECTION WITHIN BROAD SOUTHWEST LOW/MID LEVEL FLOW SPREADING CLOUDS AND SOME LIGHT PRECIPITATION ACROSS IL/IN/WI...THOUGH STILL NOT MUCH REACHING THE GROUND ACROSS WI AS PRECIPITATION STRUGGLES THROUGH DRY AIR MASS IN PLACE OVER THE WESTERN LAKES. A SECOND AREA OF PRECIPITATION STRETCHED FROM NE/EASTERN SD/WESTERN MN AHEAD OF A SHORT WAVE TROUGH COMING OUT OF CO AND FOCUSED ALONG AN AXIS OF MID LEVEL FRONTOGENESIS. ALTHOUGH F-GEN FORCING DOES NOT LOOK LIKE IT WILL IMPACT NORTHERN MI TONIGHT...COMBINATION OF PERSISTENT WARM ADVECTION AND AN ADDED BOOST FROM AFOREMENTIONED SHORT WAVE WHICH IS EXPECTED TO CROSS THE FORECAST AREA OVERNIGHT SHOULD RESULT IN AN INCREASE IN PRECIPITATION COVERAGE DURING THE LATE AFTERNOON AND THROUGH THE EVENING HOURS. NEXT ISSUE IS PRECIPITATION TYPE... TEMPERATURES HAVE WARMED QUITE NICELY ACROSS THE REGION THIS AFTERNOON...MID/UPPER 30S ACROSS EASTERN UPPER/NORTHEAST AND NORTH CENTRAL LOWER...WITH MID/UPPER 40S ALONG THE LAKE MICHIGAN SHORELINE AIDED BY DOWNSLOPE WIND COMPONENT. MODEL VERTICAL TEMPERATURE PROFILES ARE QUITE DIFFERENT TONIGHT...WITH THE GFS BEING COLDER THAN THE NAM. EARLY AFTERNOON AIRCRAFT SOUNDINGS OUT OF PLN/CIU ARE SIMILAR TO GUIDANCE 6H FORECASTS...BUT SUGGEST THAT SOMETHING IN BETWEEN IS PROBABLY MORE REFLECTIVE OF REALITY. THE MAIN CONCERN WILL BE ACROSS EASTERN UPPER WHERE COLUMN ALOFT SHOULD BE COLD ENOUGH FOR ALL SNOW...SO PRECIP TYPE WILL BE FOCUSED ON DEPTH OF SURFACE BASED WARM LAYER. BOTH NAM/GFS SUGGESTING THAT SURFACE BASED WARM LAYER WILL BE MINIMAL/NON-EXISTENT AND THAT PRECIP WILL BE ALL SNOW. PROBLEM IS THAT SURFACE TEMPERATURES IN BOTH MODELS ARE RUNNING WELL SHORT OF CURRENT OBSERVATIONS (A GOOD 4-8 DEGREES)...WITH MID/UPPER 40S TEMPERATURES FLOODING UP THROUGH THE STRAITS AND INTO AT LEAST MACKINAC COUNTY (ERY UP TO 43F AT 20Z...MCD AT 45F). LOSS OF DIURNAL HEATING AND WET BULB COOLING WILL HAVE SOME IMPACT...BUT CURRENT THINKING IS THAT BEST CHANCE FOR SNOW OR MIXED RAIN/SNOW WILL BE ACROSS NORTHERN AND PERHAPS FAR EASTERN PORTIONS OF CHIPPEWA COUNTY. GIVEN SURGE IN SURFACE TEMPERATURES THIS AFTERNOON APPEARS FREEZING RAIN THREAT ACROSS NORTHEAST LOWER WILL BE MINIMAL...ONLY REAL CONCERN IS HIGHER TERRAIN ACROSS INTERIOR NORTHERN LOWER. EXPECT PRECIPITATION TO TAPER OFF TO DRIZZLE LATE AS MID LEVEL MOISTURE GETS STRIPPED OUT IN WAKE OF SHORT WAVE TROUGH. ONSET OF PRECIPITATION MAY ALSO BRING A PERIOD OF STRONG WINDS DUE TO THE DRY LOW LEVELS. GUSTS IN EXCESS OF 40 MPH WILL BE POSSIBLE THIS EVENING. JPB REMAINDER OF THE FORECAST (TUESDAY THROUGH NEXT MONDAY)...A VERY BUSY STRETCH OF WEATHER IS EXPECTED OVER THE NEXT SEVERAL DAYS. THE MAIN FORECAST CONCERNS WILL REVOLVE AROUND THE DETAILS OF A VIGOROUS WEATHER SYSTEM MOVING ACROSS THE AREA TUESDAY NIGHT AND WEDNESDAY INCLUDING WHETHER OR NOT HEADLINES WILL BE NECESSARY. THEREAFTER...POPS WILL BE THE MAIN ISSUE AS THE PATTERN REMAINS RATHER ACTIVE. TUESDAY...RELATIVE LULL IN THE ACTION AS THE FIRST AREA OF LOW PRESSURE CONTINUES TO TRACK ACROSS ONTARIO. DO NOT BE FOOLED THOUGH AS AN ARCTIC COLD FRONT WILL BE LURKING ACROSS THE MID MISSISSIPPI VALLEY. MODEL SOUNDINGS/CROSS SECTIONS SHOW MOISTURE SWALLOWING OUT...MAINLY CONFINED TO BELOW 800 MB. THEREFORE...WILL CONTINUE WITH ONLY A CHANCE OF LIGHT RAIN AND DRIZZLE FOR MUCH OF THE DAY. HIGHS OF WELL INTO THE 30S TO AROUND 40 EXPECTED WITH SOUTH SOUTHWEST WINDS OF BETWEEN 10 AND 20 MPH. LATE TUESDAY INTO TUESDAY NIGHT...STRONG FORCING ALONG WITH ABUNDANT MOISTURE OUT AHEAD OF THE VIGOROUS COLD FRONT WILL QUICKLY OVERSPREAD THE REGION FROM THE WEST LEADING TO RAINFALL ACROSS THE ENTIRE FORECAST AREA LATE IN THE AFTERNOON. THE ARCTIC COLD FRONT THEN PLOWS ACROSS THE REGION IN THE EVENING WITH VERY STRONG COLD AIR ADVECTION BEHIND IT (850 MB TEMPERATURES PLUMMET FROM AROUND PLUS 4 C AT 00Z TUE TO BETWEEN -20 AND -25 C AT 12Z) LEADING TO FALLING TEMPERATURES LIKELY LEADING TO A RAPID FREEZE UP OF AREA ROADWAYS. MEANWHILE...A WAVE OF LOW PRESSURE MOVES UP ALONG THE FRONT WHILE RAPIDLY INTENSIFYING TO BETWEEN 975 AND 980 MB. 925 MB WINDS OF 35 TO 40 KNOTS ARE NOT EXPECTED TO HAVE TOO MUCH OF A PROBLEM MIXING DOWN WHICH WOULD LEAD TO THE POTENTIAL FOR BLIZZARD LIKE CONDITIONS DEVELOPING AT TIMES TUESDAY EVENING AND TUESDAY NIGHT (AND GALES ACROSS NEARSHORE ZONES). THEREFORE...WILL ISSUE A WINTER STORM WATCH FROM TUE EVENING THROUGH WED ACROSS ALL ZONES EXCEPT GLADWIN AND ARENAC COUNTIES FOR THE COMBINATION OF STRONG WINDS...LOW VISIBILITIES AND LOW WIND CHILLS. ACCUMULATIONS WED NIGHT ARE EXPECTED TO RANGE FROM AN INCH OR TWO SOUTHEAST TO FOUR OR FIVE INCHES ACROSS EASTERN UPPER WHERE THE BEST WRAP AROUND MOISTURE IS SHOWN. TEMPERATURES WILL PLUNGE OVERNIGHT ENDING UP BETWEEN 10 AND 15 DEGREES BY WED MORNING. WEDNESDAY...850 MB TEMPERATURES BOTTOM OUT BETWEEN -23 AND -28 C. THE MEAN SURFACE-850 MB FLOW SETTLES IN OUT OF THE WEST LEADING TO LAKE EFFECT SNOW SHOWERS. MEAN 900-700 MB RH FALLS FROM BETWEEN 70 AND 80 PERCENT IN THE MORNING TO BETWEEN 30 AND 50 PERCENT IN THE AFTERNOON. MEAN 1000-850 MB WINDS REMAIN ABOUT 30 KNOTS THROUGH THE DAY SO LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO BE PUSHED ALL THE WAY TO THE LAKE HURON SHORELINE. ACCUMULATIONS DO NOT LOOK OVERLY IMPRESSIVE AS COLD THERMAL REGIME WOULD SUPPORT SMALL SNOWFLAKE PRODUCTION SO A COUPLE OF INCHES EXPECTED IN WESTERLY FLOW FAVORED AREAS AND AN INCH OR LESS ELSEWHERE. HOWEVER...EXTENSIVE BLOWING AND DRIFTING SNOW IS EXPECTED TO CONTINUE LEADING TO POTENTIAL FOR HAZARDOUS TRAVEL CONDITIONS. TEMPERATURES WILL REMAIN NEARLY STEADY IN THE TEENS OR FALL INTO THE UPPER SINGLE DIGITS AS COLD AIR ADVECTION CONTINUES. WIND CHILLS VALUES COULD BE AS LOW AS 10 TO 15 DEGREES BELOW ZERO. WEDNESDAY NIGHT INTO THURSDAY...LAKE EFFECT IS EXPECTED TO LINGER AS 850 MB TEMPERATURES BEGIN TO STEADILY RISE BACK INTO THE -10 TO -15 C RANGE. THE FLOW IS SHOWN TO BACK FROM THE WEST INTO THE SOUTHWEST BY THURSDAY. LOWS WED NIGHT WITHIN A FEW DEGREES EITHER SIDE OF ZERO. HIGHS ON THURSDAY RANGING FROM THE UPPER TEENS TO THE MIDDLE 20S. FRIDAY THROUGH NEXT MONDAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN ENERGETIC SOUTHERN JET STREAM SENDING ENERGY NORTHWARD TOWARD THE GREAT LAKES. THERE IS THE POTENTIAL FOR MAJOR STORM SYSTEM TO AFFECT THE REGION ON FRIDAY AND AGAIN SOMETIME EARLY NEXT WEEK. IN BETWEEN...AN ALBERTA CLIPPER WILL BRING A CHANCE OF LIGHT SNOW LATE SATURDAY INTO SATURDAY NIGHT. NO ARCTIC AIR IS IN SIGHT WITH SEASONABLE TEMPERATURES EXPECTED WITH HIGHS IN THE UPPER 20S TO LOWER 30S AND LOWS IN THE TEENS. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ008-015>036. LM...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LMZ323-341-342-344>346. LH...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LHZ345>349. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
655 PM EST MON JAN 28 2008 .AVIATION...LOW LEVEL WIND SHEAR ANTICIPATED LATER THIS EVENING AND OVERNIGHT AT PLN/TVC/APN. AREA OF LIGHT TO MODERATE RAIN SHOWERS WILL MOVE THROUGH NORTHERN LOWER MICHIGAN EARLY THIS EVENING... HEAVIEST OF THE SHOWER ACTIVITY IMPACTING PLN/APN THROUGH 03Z. HOWEVER...DRY LOW LEVEL AIR WILL KEEP CIGS MAINLY VFR THROUGH THIS TIME. ANOTHER ROUND OF RAINFALL MAY DEVELOP UPSTREAM OVER WISCONSIN AND MOVE THROUGH THE REGION BETWEEN 03Z AND 09Z...BUT WILL SEE HOW THAT GOES. IN ANY EVENT...CIGS LOWERING TO MVFR ANTICIPATED LATE THIS EVENING AND OVERNIGHT AS THE LOW LEVELS SATURATE. ON TUESDAY... LIGHT RAIN AND DRIZZLE CONDITIONS EXPECTED TO PREVAIL WHILE IFR CIGS TAKE HOLD. ADAM && .DISCUSSION...ISSUED AT 345 PM. SHORT TERM (TONIGHT)...986MB SURFACE LOW OVER ND LATE THIS AFTERNOON WILL CONTINUE TO STRENGTHEN AS IT SLIDES TO A POSITION OFF THE NORTH SHORE OF LAKE SUPERIOR TUESDAY MORNING. WARM ADVECTION WITHIN BROAD SOUTHWEST LOW/MID LEVEL FLOW SPREADING CLOUDS AND SOME LIGHT PRECIPITATION ACROSS IL/IN/WI...THOUGH STILL NOT MUCH REACHING THE GROUND ACROSS WI AS PRECIPITATION STRUGGLES THROUGH DRY AIR MASS IN PLACE OVER THE WESTERN LAKES. A SECOND AREA OF PRECIPITATION STRETCHED FROM NE/EASTERN SD/WESTERN MN AHEAD OF A SHORT WAVE TROUGH COMING OUT OF CO AND FOCUSED ALONG AN AXIS OF MID LEVEL FRONTOGENESIS. ALTHOUGH F-GEN FORCING DOES NOT LOOK LIKE IT WILL IMPACT NORTHERN MI TONIGHT...COMBINATION OF PERSISTENT WARM ADVECTION AND AN ADDED BOOST FROM AFOREMENTIONED SHORT WAVE WHICH IS EXPECTED TO CROSS THE FORECAST AREA OVERNIGHT SHOULD RESULT IN AN INCREASE IN PRECIPITATION COVERAGE DURING THE LATE AFTERNOON AND THROUGH THE EVENING HOURS. NEXT ISSUE IS PRECIPITATION TYPE... TEMPERATURES HAVE WARMED QUITE NICELY ACROSS THE REGION THIS AFTERNOON...MID/UPPER 30S ACROSS EASTERN UPPER/NORTHEAST AND NORTH CENTRAL LOWER...WITH MID/UPPER 40S ALONG THE LAKE MICHIGAN SHORELINE AIDED BY DOWNSLOPE WIND COMPONENT. MODEL VERTICAL TEMPERATURE PROFILES ARE QUITE DIFFERENT TONIGHT...WITH THE GFS BEING COLDER THAN THE NAM. EARLY AFTERNOON AIRCRAFT SOUNDINGS OUT OF PLN/CIU ARE SIMILAR TO GUIDANCE 6H FORECASTS...BUT SUGGEST THAT SOMETHING IN BETWEEN IS PROBABLY MORE REFLECTIVE OF REALITY. THE MAIN CONCERN WILL BE ACROSS EASTERN UPPER WHERE COLUMN ALOFT SHOULD BE COLD ENOUGH FOR ALL SNOW...SO PRECIP TYPE WILL BE FOCUSED ON DEPTH OF SURFACE BASED WARM LAYER. BOTH NAM/GFS SUGGESTING THAT SURFACE BASED WARM LAYER WILL BE MINIMAL/NON-EXISTENT AND THAT PRECIP WILL BE ALL SNOW. PROBLEM IS THAT SURFACE TEMPERATURES IN BOTH MODELS ARE RUNNING WELL SHORT OF CURRENT OBSERVATIONS (A GOOD 4-8 DEGREES)...WITH MID/UPPER 40S TEMPERATURES FLOODING UP THROUGH THE STRAITS AND INTO AT LEAST MACKINAC COUNTY (ERY UP TO 43F AT 20Z...MCD AT 45F). LOSS OF DIURNAL HEATING AND WET BULB COOLING WILL HAVE SOME IMPACT...BUT CURRENT THINKING IS THAT BEST CHANCE FOR SNOW OR MIXED RAIN/SNOW WILL BE ACROSS NORTHERN AND PERHAPS FAR EASTERN PORTIONS OF CHIPPEWA COUNTY. GIVEN SURGE IN SURFACE TEMPERATURES THIS AFTERNOON APPEARS FREEZING RAIN THREAT ACROSS NORTHEAST LOWER WILL BE MINIMAL...ONLY REAL CONCERN IS HIGHER TERRAIN ACROSS INTERIOR NORTHERN LOWER. EXPECT PRECIPITATION TO TAPER OFF TO DRIZZLE LATE AS MID LEVEL MOISTURE GETS STRIPPED OUT IN WAKE OF SHORT WAVE TROUGH. ONSET OF PRECIPITATION MAY ALSO BRING A PERIOD OF STRONG WINDS DUE TO THE DRY LOW LEVELS. GUSTS IN EXCESS OF 40 MPH WILL BE POSSIBLE THIS EVENING. JPB REMAINDER OF THE FORECAST (TUESDAY THROUGH NEXT MONDAY)...A VERY BUSY STRETCH OF WEATHER IS EXPECTED OVER THE NEXT SEVERAL DAYS. THE MAIN FORECAST CONCERNS WILL REVOLVE AROUND THE DETAILS OF A VIGOROUS WEATHER SYSTEM MOVING ACROSS THE AREA TUESDAY NIGHT AND WEDNESDAY INCLUDING WHETHER OR NOT HEADLINES WILL BE NECESSARY. THEREAFTER...POPS WILL BE THE MAIN ISSUE AS THE PATTERN REMAINS RATHER ACTIVE. TUESDAY...RELATIVE LULL IN THE ACTION AS THE FIRST AREA OF LOW PRESSURE CONTINUES TO TRACK ACROSS ONTARIO. DO NOT BE FOOLED THOUGH AS AN ARCTIC COLD FRONT WILL BE LURKING ACROSS THE MID MISSISSIPPI VALLEY. MODEL SOUNDINGS/CROSS SECTIONS SHOW MOISTURE SWALLOWING OUT...MAINLY CONFINED TO BELOW 800 MB. THEREFORE...WILL CONTINUE WITH ONLY A CHANCE OF LIGHT RAIN AND DRIZZLE FOR MUCH OF THE DAY. HIGHS OF WELL INTO THE 30S TO AROUND 40 EXPECTED WITH SOUTH SOUTHWEST WINDS OF BETWEEN 10 AND 20 MPH. LATE TUESDAY INTO TUESDAY NIGHT...STRONG FORCING ALONG WITH ABUNDANT MOISTURE OUT AHEAD OF THE VIGOROUS COLD FRONT WILL QUICKLY OVERSPREAD THE REGION FROM THE WEST LEADING TO RAINFALL ACROSS THE ENTIRE FORECAST AREA LATE IN THE AFTERNOON. THE ARCTIC COLD FRONT THEN PLOWS ACROSS THE REGION IN THE EVENING WITH VERY STRONG COLD AIR ADVECTION BEHIND IT (850 MB TEMPERATURES PLUMMET FROM AROUND PLUS 4 C AT 00Z TUE TO BETWEEN -20 AND -25 C AT 12Z) LEADING TO FALLING TEMPERATURES LIKELY LEADING TO A RAPID FREEZE UP OF AREA ROADWAYS. MEANWHILE...A WAVE OF LOW PRESSURE MOVES UP ALONG THE FRONT WHILE RAPIDLY INTENSIFYING TO BETWEEN 975 AND 980 MB. 925 MB WINDS OF 35 TO 40 KNOTS ARE NOT EXPECTED TO HAVE TOO MUCH OF A PROBLEM MIXING DOWN WHICH WOULD LEAD TO THE POTENTIAL FOR BLIZZARD LIKE CONDITIONS DEVELOPING AT TIMES TUESDAY EVENING AND TUESDAY NIGHT (AND GALES ACROSS NEARSHORE ZONES). THEREFORE...WILL ISSUE A WINTER STORM WATCH FROM TUE EVENING THROUGH WED ACROSS ALL ZONES EXCEPT GLADWIN AND ARENAC COUNTIES FOR THE COMBINATION OF STRONG WINDS...LOW VISIBILITIES AND LOW WIND CHILLS. ACCUMULATIONS WED NIGHT ARE EXPECTED TO RANGE FROM AN INCH OR TWO SOUTHEAST TO FOUR OR FIVE INCHES ACROSS EASTERN UPPER WHERE THE BEST WRAP AROUND MOISTURE IS SHOWN. TEMPERATURES WILL PLUNGE OVERNIGHT ENDING UP BETWEEN 10 AND 15 DEGREES BY WED MORNING. WEDNESDAY...850 MB TEMPERATURES BOTTOM OUT BETWEEN -23 AND -28 C. THE MEAN SURFACE-850 MB FLOW SETTLES IN OUT OF THE WEST LEADING TO LAKE EFFECT SNOW SHOWERS. MEAN 900-700 MB RH FALLS FROM BETWEEN 70 AND 80 PERCENT IN THE MORNING TO BETWEEN 30 AND 50 PERCENT IN THE AFTERNOON. MEAN 1000-850 MB WINDS REMAIN ABOUT 30 KNOTS THROUGH THE DAY SO LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO BE PUSHED ALL THE WAY TO THE LAKE HURON SHORELINE. ACCUMULATIONS DO NOT LOOK OVERLY IMPRESSIVE AS COLD THERMAL REGIME WOULD SUPPORT SMALL SNOWFLAKE PRODUCTION SO A COUPLE OF INCHES EXPECTED IN WESTERLY FLOW FAVORED AREAS AND AN INCH OR LESS ELSEWHERE. HOWEVER...EXTENSIVE BLOWING AND DRIFTING SNOW IS EXPECTED TO CONTINUE LEADING TO POTENTIAL FOR HAZARDOUS TRAVEL CONDITIONS. TEMPERATURES WILL REMAIN NEARLY STEADY IN THE TEENS OR FALL INTO THE UPPER SINGLE DIGITS AS COLD AIR ADVECTION CONTINUES. WIND CHILLS VALUES COULD BE AS LOW AS 10 TO 15 DEGREES BELOW ZERO. WEDNESDAY NIGHT INTO THURSDAY...LAKE EFFECT IS EXPECTED TO LINGER AS 850 MB TEMPERATURES BEGIN TO STEADILY RISE BACK INTO THE -10 TO -15 C RANGE. THE FLOW IS SHOWN TO BACK FROM THE WEST INTO THE SOUTHWEST BY THURSDAY. LOWS WED NIGHT WITHIN A FEW DEGREES EITHER SIDE OF ZERO. HIGHS ON THURSDAY RANGING FROM THE UPPER TEENS TO THE MIDDLE 20S. FRIDAY THROUGH NEXT MONDAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN ENERGETIC SOUTHERN JET STREAM SENDING ENERGY NORTHWARD TOWARD THE GREAT LAKES. THERE IS THE POTENTIAL FOR MAJOR STORM SYSTEM TO AFFECT THE REGION ON FRIDAY AND AGAIN SOMETIME EARLY NEXT WEEK. IN BETWEEN...AN ALBERTA CLIPPER WILL BRING A CHANCE OF LIGHT SNOW LATE SATURDAY INTO SATURDAY NIGHT. NO ARCTIC AIR IS IN SIGHT WITH SEASONABLE TEMPERATURES EXPECTED WITH HIGHS IN THE UPPER 20S TO LOWER 30S AND LOWS IN THE TEENS. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ008-015>036. LM...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LMZ323-341-342-344>346. LH...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LHZ345>349. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
345 PM EST MON JAN 28 2008 .DISCUSSION...SHORT TERM (TONIGHT)...986MB SURFACE LOW OVER ND LATE THIS AFTERNOON WILL CONTINUE TO STRENGTHEN AS IT SLIDES TO A POSITION OFF THE NORTH SHORE OF LAKE SUPERIOR TUESDAY MORNING. WARM ADVECTION WITHIN BROAD SOUTHWEST LOW/MID LEVEL FLOW SPREADING CLOUDS AND SOME LIGHT PRECIPITATION ACROSS IL/IN/WI...THOUGH STILL NOT MUCH REACHING THE GROUND ACROSS WI AS PRECIPITATION STRUGGLES THROUGH DRY AIR MASS IN PLACE OVER THE WESTERN LAKES. A SECOND AREA OF PRECIPITATION STRETCHED FROM NE/EASTERN SD/WESTERN MN AHEAD OF A SHORT WAVE TROUGH COMING OUT OF CO AND FOCUSED ALONG AN AXIS OF MID LEVEL FRONTOGENESIS. ALTHOUGH F-GEN FORCING DOES NOT LOOK LIKE IT WILL IMPACT NORTHERN MI TONIGHT...COMBINATION OF PERSISTENT WARM ADVECTION AND AN ADDED BOOST FROM AFOREMENTIONED SHORT WAVE WHICH IS EXPECTED TO CROSS THE FORECAST AREA OVERNIGHT SHOULD RESULT IN AN INCREASE IN PRECIPITATION COVERAGE DURING THE LATE AFTERNOON AND THROUGH THE EVENING HOURS. NEXT ISSUE IS PRECIPITATION TYPE... TEMPERATURES HAVE WARMED QUITE NICELY ACROSS THE REGION THIS AFTERNOON...MID/UPPER 30S ACROSS EASTERN UPPER/NORTHEAST AND NORTH CENTRAL LOWER...WITH MID/UPPER 40S ALONG THE LAKE MICHIGAN SHORELINE AIDED BY DOWNSLOPE WIND COMPONENT. MODEL VERTICAL TEMPERATURE PROFILES ARE QUITE DIFFERENT TONIGHT...WITH THE GFS BEING COLDER THAN THE NAM. EARLY AFTERNOON AIRCRAFT SOUNDINGS OUT OF PLN/CIU ARE SIMILAR TO GUIDANCE 6H FORECASTS...BUT SUGGEST THAT SOMETHING IN BETWEEN IS PROBABLY MORE REFLECTIVE OF REALITY. THE MAIN CONCERN WILL BE ACROSS EASTERN UPPER WHERE COLUMN ALOFT SHOULD BE COLD ENOUGH FOR ALL SNOW...SO PRECIP TYPE WILL BE FOCUSED ON DEPTH OF SURFACE BASED WARM LAYER. BOTH NAM/GFS SUGGESTING THAT SURFACE BASED WARM LAYER WILL BE MINIMAL/NON-EXISTENT AND THAT PRECIP WILL BE ALL SNOW. PROBLEM IS THAT SURFACE TEMPERATURES IN BOTH MODELS ARE RUNNING WELL SHORT OF CURRENT OBSERVATIONS (A GOOD 4-8 DEGREES)...WITH MID/UPPER 40S TEMPERATURES FLOODING UP THROUGH THE STRAITS AND INTO AT LEAST MACKINAC COUNTY (ERY UP TO 43F AT 20Z...MCD AT 45F). LOSS OF DIURNAL HEATING AND WET BULB COOLING WILL HAVE SOME IMPACT...BUT CURRENT THINKING IS THAT BEST CHANCE FOR SNOW OR MIXED RAIN/SNOW WILL BE ACROSS NORTHERN AND PERHAPS FAR EASTERN PORTIONS OF CHIPPEWA COUNTY. GIVEN SURGE IN SURFACE TEMPERATURES THIS AFTERNOON APPEARS FREEZING RAIN THREAT ACROSS NORTHEAST LOWER WILL BE MINIMAL...ONLY REAL CONCERN IS HIGHER TERRAIN ACROSS INTERIOR NORTHERN LOWER. EXPECT PRECIPITATION TO TAPER OFF TO DRIZZLE LATE AS MID LEVEL MOISTURE GETS STRIPPED OUT IN WAKE OF SHORT WAVE TROUGH. ONSET OF PRECIPITATION MAY ALSO BRING A PERIOD OF STRONG WINDS DUE TO THE DRY LOW LEVELS. GUSTS IN EXCESS OF 40 MPH WILL BE POSSIBLE THIS EVENING. JPB REMAINDER OF THE FORECAST (TUESDAY THROUGH NEXT MONDAY)...A VERY BUSY STRETCH OF WEATHER IS EXPECTED OVER THE NEXT SEVERAL DAYS. THE MAIN FORECAST CONCERNS WILL REVOLVE AROUND THE DETAILS OF A VIGOROUS WEATHER SYSTEM MOVING ACROSS THE AREA TUESDAY NIGHT AND WEDNESDAY INCLUDING WHETHER OR NOT HEADLINES WILL BE NECESSARY. THEREAFTER...POPS WILL BE THE MAIN ISSUE AS THE PATTERN REMAINS RATHER ACTIVE. TUESDAY...RELATIVE LULL IN THE ACTION AS THE FIRST AREA OF LOW PRESSURE CONTINUES TO TRACK ACROSS ONTARIO. DO NOT BE FOOLED THOUGH AS AN ARCTIC COLD FRONT WILL BE LURKING ACROSS THE MID MISSISSIPPI VALLEY. MODEL SOUNDINGS/CROSS SECTIONS SHOW MOISTURE SWALLOWING OUT...MAINLY CONFINED TO BELOW 800 MB. THEREFORE...WILL CONTINUE WITH ONLY A CHANCE OF LIGHT RAIN AND DRIZZLE FOR MUCH OF THE DAY. HIGHS OF WELL INTO THE 30S TO AROUND 40 EXPECTED WITH SOUTH SOUTHWEST WINDS OF BETWEEN 10 AND 20 MPH. LATE TUESDAY INTO TUESDAY NIGHT...STRONG FORCING ALONG WITH ABUNDANT MOISTURE OUT AHEAD OF THE VIGOROUS COLD FRONT WILL QUICKLY OVERSPREAD THE REGION FROM THE WEST LEADING TO RAINFALL ACROSS THE ENTIRE FORECAST AREA LATE IN THE AFTERNOON. THE ARCTIC COLD FRONT THEN PLOWS ACROSS THE REGION IN THE EVENING WITH VERY STRONG COLD AIR ADVECTION BEHIND IT (850 MB TEMPERATURES PLUMMET FROM AROUND PLUS 4 C AT 00Z TUE TO BETWEEN -20 AND -25 C AT 12Z) LEADING TO FALLING TEMPERATURES LIKELY LEADING TO A RAPID FREEZE UP OF AREA ROADWAYS. MEANWHILE...A WAVE OF LOW PRESSURE MOVES UP ALONG THE FRONT WHILE RAPIDLY INTENSIFYING TO BETWEEN 975 AND 980 MB. 925 MB WINDS OF 35 TO 40 KNOTS ARE NOT EXPECTED TO HAVE TOO MUCH OF A PROBLEM MIXING DOWN WHICH WOULD LEAD TO THE POTENTIAL FOR BLIZZARD LIKE CONDITIONS DEVELOPING AT TIMES TUESDAY EVENING AND TUESDAY NIGHT (AND GALES ACROSS NEARSHORE ZONES). THEREFORE...WILL ISSUE A WINTER STORM WATCH FROM TUE EVENING THROUGH WED ACROSS ALL ZONES EXCEPT GLADWIN AND ARENAC COUNTIES FOR THE COMBINATION OF STRONG WINDS...LOW VISIBILITIES AND LOW WIND CHILLS. ACCUMULATIONS WED NIGHT ARE EXPECTED TO RANGE FROM AN INCH OR TWO SOUTHEAST TO FOUR OR FIVE INCHES ACROSS EASTERN UPPER WHERE THE BEST WRAP AROUND MOISTURE IS SHOWN. TEMPERATURES WILL PLUNGE OVERNIGHT ENDING UP BETWEEN 10 AND 15 DEGREES BY WED MORNING. WEDNESDAY...850 MB TEMPERATURES BOTTOM OUT BETWEEN -23 AND -28 C. THE MEAN SURFACE-850 MB FLOW SETTLES IN OUT OF THE WEST LEADING TO LAKE EFFECT SNOW SHOWERS. MEAN 900-700 MB RH FALLS FROM BETWEEN 70 AND 80 PERCENT IN THE MORNING TO BETWEEN 30 AND 50 PERCENT IN THE AFTERNOON. MEAN 1000-850 MB WINDS REMAIN ABOUT 30 KNOTS THROUGH THE DAY SO LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO BE PUSHED ALL THE WAY TO THE LAKE HURON SHORELINE. ACCUMULATIONS DO NOT LOOK OVERLY IMPRESSIVE AS COLD THERMAL REGIME WOULD SUPPORT SMALL SNOWFLAKE PRODUCTION SO A COUPLE OF INCHES EXPECTED IN WESTERLY FLOW FAVORED AREAS AND AN INCH OR LESS ELSEWHERE. HOWEVER...EXTENSIVE BLOWING AND DRIFTING SNOW IS EXPECTED TO CONTINUE LEADING TO POTENTIAL FOR HAZARDOUS TRAVEL CONDITIONS. TEMPERATURES WILL REMAIN NEARLY STEADY IN THE TEENS OR FALL INTO THE UPPER SINGLE DIGITS AS COLD AIR ADVECTION CONTINUES. WIND CHILLS VALUES COULD BE AS LOW AS 10 TO 15 DEGREES BELOW ZERO. WEDNESDAY NIGHT INTO THURSDAY...LAKE EFFECT IS EXPECTED TO LINGER AS 850 MB TEMPERATURES BEGIN TO STEADILY RISE BACK INTO THE -10 TO -15 C RANGE. THE FLOW IS SHOWN TO BACK FROM THE WEST INTO THE SOUTHWEST BY THURSDAY. LOWS WED NIGHT WITHIN A FEW DEGREES EITHER SIDE OF ZERO. HIGHS ON THURSDAY RANGING FROM THE UPPER TEENS TO THE MIDDLE 20S. FRIDAY THROUGH NEXT MONDAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN ENERGETIC SOUTHERN JET STREAM SENDING ENERGY NORTHWARD TOWARD THE GREAT LAKES. THERE IS THE POTENTIAL FOR MAJOR STORM SYSTEM TO AFFECT THE REGION ON FRIDAY AND AGAIN SOMETIME EARLY NEXT WEEK. IN BETWEEN...AN ALBERTA CLIPPER WILL BRING A CHANCE OF LIGHT SNOW LATE SATURDAY INTO SATURDAY NIGHT. NO ARCTIC AIR IS IN SIGHT WITH SEASONABLE TEMPERATURES EXPECTED WITH HIGHS IN THE UPPER 20S TO LOWER 30S AND LOWS IN THE TEENS. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ008-015>036. LM...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LMZ323-341-342-344>346. LH...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LHZ345>349. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1248 PM EST MON JAN 28 2008 UPDATED AVIATION SECTION FOR 18Z TAF ISSUANCE .UPDATE... FORECAST IS RATHER TRICKY FOR THIS AFTERNOON...PARTICULARLY WITH REGARDS TO PCPN POTENTIAL. 15Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED GENERAL UPPER LEVEL SW FLOW...BETWEEN A TROUGH OVER THE WESTERN U.S. AND A RIDGE FROM THE SOUTHERN PLAINS INTO THE EASTERN GREAT LAKES. PLENTY OF UPPER LEVEL MOISTURE STREAMING UP FROM THE EAST PACIFIC INTO THE GREAT LAKES REGION AS SEEN ON WATER VAPOR...WHICH VISIBLE SATELLITE IMAGERY AND SURFACE OBS INDICATES IS MOSTLY IN THE FORM OF HIGH CLOUDS. BELOW THESE HIGH CLOUDS...12Z RAOB AND TAMDAR SOUNDINGS ARE QUITE DRY...WITH 10-20C DEWPOINT DEPRESSIONS ACROSS THE REGION BETWEEN 900-500MB. THE SOUNDINGS DEPICT A STRONG INVERSION BETWEEN 900-850MB THANKS TO 850MB TEMPS OF 3C AT APX...7C AT GRB AND 12C AT MPX. NORMALLY THIS INVERSION WOULD MEAN TRAPPED LOW CLOUDS OVER THE AREA. HOWEVER...VISIBLE IMAGERY AND MOST SURFACE OBS (EXCLUDING SAW) SHOW VERY FEW IF ANY LOW CLOUDS ACROSS THE MIDWEST OR GREAT LAKES. THIS APPEARS MOSTLY DUE TO THE LACK OF LOW LEVEL MOISTURE...THOUGH DEWPOINTS ARE GENERALLY ON THE WAY UP NOW WITH MOST READINGS IN THE 25 TO 30 F RANGE. HIGHER DEWPOINTS...NEAR 40...ARE MOVING NORTHEAST THROUGH KS INTO SW IA ON A STRONG LOW LEVEL JET. 850MB WINDS ARE SW AT 60-65 KT AT PROFILERS ACROSS KS INTO NORTHERN MO. AT THE SURFACE...A 987MB LOW IS SITUATED NEAR BISMARCK...WITH ALL OF THE UPPER MISSISSIPPI VALLEY INTO THE GREAT LAKES IN THE WARM SECTOR. GIVEN THE PRESENCE OF SO MUCH DRY AIR IN THE LOW AND MID LEVELS...AM HIGHLY UNCERTAIN ON ANY PCPN OCCURRING TODAY. FOLLOWED THE DRIER NAM/RUC SCENARIO OVER THE GFS AS THEY SEEM TO BE DOING BETTER WITH RESPECT TO MOISTURE IN CURRENT TAMDAR SOUNDINGS. PLUS... CLIMATOLOGICALLY SPEAKING THE WARM SECTOR OF A SYSTEM IN WINTER IS NOT VERY FAVORABLE FOR PCPN BECAUSE MOISTURE IS HARDER TO COME BY. THEREFORE MADE A SOMEWHAT DRASTIC CHANGE AND WENT COMPLETELY DRY FOR TODAY. RAISED TEMPS SLIGHTLY GIVEN CURRENT READINGS ARE NEAR PREVIOUS FORECAST HIGHS...BUT HIGH CLOUDS WHICH SHOULD INCREASE THROUGH THE AFTERNOON WILL TEMPER READINGS FROM CLIMBING TOO HIGH. AS FAR AS TONIGHT GOES...WANTED TO LOWER POPS ACROSS THE BOARD...BUT THERE IS A BIT MORE DYNAMICAL FORCING TAKING PLACE. OVER THE WESTERN U.P....MODELS INDICATE SOME MID-LEVEL FRONTOGENESIS AND POSSIBLE JET COUPLING TAKING PLACE...WHICH COULD FORCE SATURATION AND PCPN. IN THE FAR EASTERN U.P....ISENTROPIC LIFT MOVING UP THROUGH MISSOURI INTO ILLINOIS (NOTED BY THICK MID-CLOUDS THERE) HEADS NORTHEAST AND COULD PRODUCE SOME LIGHT PCPN. THE CENTRAL U.P. GETS STUCK IN-BETWEEN PERHAPS INTO A DRIZZLE/FREEZING DRIZZLE. WILL SOMEWHAT HEDGE THE GOING FORECAST TOWARDS THIS SCENARIO...WITH MORE CHANGES FORTHCOMING ONCE THE 12Z GFS COMES IN TO SEE IF IT HANDLES THE MOISTURE BETTER. && .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE STORM POTENTIAL FOR TUESDAY THROUGH WEDNESDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER THE PACIFIC NORTHWEST AND A FLATTEN RIDGE OVER GREAT LAKES REGION. A CLOSED LOW IS JUST OFF THE COAST OF THE MID ATLANTIC STATES. WEAK SHORTWAVES ARE OVER WESTERN ONTARIO...NORTH DAKOTA...AND WYOMING. SURFACE ANALYSIS DEPICTS A LOW OVER NORTH DAKOTA WITH A WARM FRONT LEADING IT STRETCHING INTO ILLINOIS. ANOTHER FRONTAL SYSTEM EXTENDS FROM WINNIPEG EAST TO JAMES BAY. AN ELONGATED RIDGE STRETCHES FROM GEORGIA NORTHEAST INTO SOUTHERN QUEBEC. THERE IS SOME FOG OVER THE EASTERN OHIO RIVER VALLEY AND THE LOWER GREAT LAKES. THE PACIFIC NORTHWEST LONGWAVE WILL SHIFT INTO THE NORTHERN HIGH PLAINS TODAY. THE RIDGE OVER THE GREAT LAKES WILL SHIFT INTO THE LOWER GREAT LAKES REGION AS THE LOW OFF THE ATLANTIC COAST WORKS NORTHEAST. THE SHORTWAVE CLIMBING THE RIDGE WILL GENERALLY STAY NORTH OF THE AREA TODAY...EXCEPT FOR THE SHORTWAVE OVER WYOMING WHICH WILL RACE UP THE RIDGE INTO THE FORECAST AREA THIS AFTERNOON. THE NOSE OF A 100+ KNOT UPPER LEVEL JET WILL SHIFT INTO WESTERN U.P. BY LATE AFTERNOON. THE SURFACE LOW OVER MONTANA WILL CATCH UP WITH THE LOW OVER NORTH DAKOTA AND MERGE AS THEY MOVE INTO WESTERN MINNESOTA. THE ACCOMPANYING WARM FRONT WILL SHIFT INTO WISCONSIN. THE LARGE RIDGE OVER THE EAST COAST APPEARS TO BE STEERING EVERYTHING NORTHEAST. THE RIDGE KEEPS A SOUTHERLY FLOW THROUGHOUT THE EASTERN CONUS DRAWING WARM AIR INTO THE GREAT LAKES REGION. THIS SHOULD PUSH TEMPERATURES INTO THE MID AND UPPER 30S OVER THE U.P. TODAY. THE INSTABILITY WITH THE SHORTWAVE...ISENTROPIC ASCENT AHEAD OF THE FRONTAL SYSTEM...AND LOW LEVEL MOISTURE WILL GENERATE PRECIPITATION. AN 850MB THERMAL TROUGH WILL SHIFT INTO THE AREA BY LATE AFTERNOON ALONG WITH CLOUD COVER. THE FORECAST SOUNDING PROFILE AND WARMER SURFACE TEMPERATURES SUGGEST THAT THERE WILL BE A MIX OF RAIN AND SNOW. A 50KNOT LOW LEVEL JET WILL SWEEP ACROSS THE FORECAST AREA TODAY. THE WARM SURFACE TEMPERATURES WILL HELP TO MIX SOME OF THESE WINDS TO THE SURFACE. MODELS IN PRETTY GOOD AGREEMENT WITH THE SYSTEM MOVING INTO THE GREAT LAKES WITH THE NAM ONLY A LITTLE FARTHER NORTH THAN THE CONSENSUS AND THE UKMET SLIGHTLY SLOWER. AS SUGGESTED BY HPC WILL GO WITH THE GFS/ECMWF BLEND. THE LONGWAVE TROUGH WILL MOVE INTO THE DAKOTA AND CENTRAL CANADA TONIGHT. SHORTWAVES EJECTED OUT AHEAD OF THE TROUGH WILL SWEEP THROUGH THE AREA TONIGHT. THE SURFACE LOW WILL MOVE OUT OF MINNESOTA AND INTO CENTRAL ONTARIO BY MIDNIGHT DRAGGING THE COLD FRONT INTO THE WESTERN U.P. AND LAKE SUPERIOR. WINDS AT THAT TIME WILL BEGIN TO VEER WEST AND NORTHWEST. ISENTROPIC ASCENT AHEAD OF THE FRONT AND WARM MOISTURE AIR WILL CONTINUE TO FEED RAINS OVER THE AREA. AS THE FRONT MOVES INTO THE AREA LATE TONIGHT...COLD AIR WILL ADVECT IN AND CHANGE THE RAIN TO SNOW OVER THE WESTERN U.P. THE TEMPERATURES WILL DROP RAPIDLY FOLLOWING THE FROPA. A SECONDARY LOW DEVELOPING ALONG THIS FRONT WILL WORK NORTHWARD ALONG THE FRONT AND REACH EASTERN IOWA BY SUNRISE. THE LONGWAVE TROUGH WILL REACH MINNESOTA AND EASTERN MANITOBA BY LATE TUESDAY AFTERNOON. WEAK SHORTWAVES AHEAD OF THE TROUGH WILL SWEEP THROUGH THE FORECAST AREA. THE SURFACE LOW WILL LIFT INTO NORTHEAST ONTARIO DRAGGING THE COLD FRONT INTO THE EASTERN U.P. THE SURFACE LOW MOVING UP THE FRONT AND WILL REACH NORTHERN LOWER MICHIGAN BY LATE TUESDAY. A -32C 850MB THERMAL WILL SHIFT INTO MINNESOTA. LOW LEVEL MOISTURE AND INSTABILITY ALONG WITH THE COLD AIR SPREADING ACROSS THE AREA WILL CHANGE THE PRECIPITATION TO SNOW BY LATE MORNING. THE TIGHT GRADIENTS BEHIND THE FRONT WILL INCREASE THE WINDS OVER THE WEST. THIS WILL PRODUCE SOME BLOWING SNOW BY LATE AFTERNOON. THE LONGWAVE TROUGH WILL MOVE OVER THE FORECAST AREA TUESDAY NIGHT. THE SURFACE LOW WILL TRACK TO EAST CENTRAL ONTARIO DRAGGING THE COLD FRONT THROUGH THE LOWER GREAT LAKES INTO THE MID ATLANTIC STATES. THE CENTRAL PLAINS RIDGE WILL ADVANCE INTO THE MIDDLE MISSISSIPPI RIVER VALLEY. THE 850MB THERMAL TROUGH WILL SHIFT INTO WESTERN LAKE SUPERIOR. WINDS WILL BE MAINLY FROM THE WEST TO NORTHWEST ACROSS LAKE SUPERIOR. A 40KNOT LOW LEVEL JET WILL SETTLE OVER THE FORECAST AREA OVERNIGHT. THE COLD 850MB TEMPERATURES WILL PROMOTE MIXING SOME OF THESE WINDS TO THE SURFACE. THE COLD TEMPERATURES AND WINDS WILL GENERATE LAKE EFFECT SNOWS AND BLOWING SNOW MAINLY OVER THE WEST END. A WINTER STORMS WATCH MAY BE WARRANTED. WIND CHILLS COULD REACH ADVISORY CATEGORY LATE. SINCE IT COULD BE AN ADVISORY WILL HOLD OFF ON ISSUING IT AT THIS TIME. THE LONGWAVE TROUGH WILL SWING INTO NORTHERN ONTARIO AND SOUTHERN QUEBEC ON WEDNESDAY. THE SURFACE LOW WILL LIKEWISE SWING INTO QUEBEC WHILE THE RIDGE PUSHES DEEPER INTO THE UPPER MISSISSIPPI RIVER VALLEY. ANTI-CYCLONIC FLOW WILL DRAW COLDER AIR INTO THE UPPER GREAT LAKES REGION. DRY AIR WILL OVERSPREAD THE REGION AS WELL. THE THERMAL TROUGH WILL SUPPORT LOW LEVEL INSTABILITY AND LAKE EFFECT SNOWS. THE WINDS WILL MIX DOWN OVER LAKE SUPERIOR SO EXPECT TO SEE MORE BLOWING SNOW. WITH THE TEMPERATURES AS COLD AS IT WILL BE...EXPECT TO SEE FINER FLAKES WHICH WITH THE WINDS WILL REDUCE VISIBILITY GREATLY. THE LONGER FETCH ACROSS THE CENTRAL AND EASTERN PART OF LAKE SUPERIOR WILL CONTRIBUTE GREATLY TO SIGNIFICANT LES OVER THE LUCE...ALGER AND EVEN NORTHERN SCHOOLCRAFT COUNTIES. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... TAF FORECAST IS VERY TRICKY...PARTICULARLY WITH REGARDS TO CEILINGS GIVEN THE FACT THAT MUCH OF THE UPPER MISSISSIPPI VALLEY INTO THE GREAT LAKES HAS NO LOW CLOUDS AT ALL AS OF 1730Z. FOR CMX...CLOUD COVER OVER THE DAKOTAS CONTINUES TO BECOME THICKER AHEAD OF AN UPPER LEVEL DISTURBANCE OVER SE COLORADO. AS THIS DISTURBANCE LIFTS NE AND BRINGS MOISTURE UP FROM THE CENTRAL PLAINS...THESE CLOUDS SHOULD LOWER...WITH ENOUGH FORCING TO PRODUCE SOME -RA OR -SN AFTER 02Z. FOR NOW JUST WENT WITH A LOWERING TO MVFR AND PROB30S FOR POSSIBLY SOME LOWER VSBYS AND CEILINGS. A COLD FRONT SLOWLY PASSING TOMORROW MORNING WILL RAPIDLY INCREASE THE WINDS...BUT COLD ENOUGH AIR TO PRODUCE LAKE EFFECT SNOW IS NOT INDICATED UNTIL 17/18Z...AND THUS HAVE LEFT THAT OUT FOR NOW. AT SAW...THE DISTURBANCE MENTIONED AT CMX IS A BIT TOO FAR WEST TO PROVIDE MUCH FORCING FOR PCPN. HOWEVER...THE PERSISTENT BRINGING UP OF MOISTURE FROM KANSAS INTO THE COLDER AIRMASS OVER UPPER MICHIGAN (THANKS ALSO IN PART FROM SNOWPACK MELTING)...WILL LIKELY RESULT IN SOME LOW CLOUD DECK OVER THE AREA. LOOKS LIKE SOMEWHERE AROUND 03Z THIS SHOULD FORM...WITH THE POSSIBILITY OF SOME IFR MIST/DRIZZLE CONDITIONS. THE COLD FRONT MOVING IN TUE MORNING COULD ACTUALLY CLEAR THE SKIES UP SOME...AND AT THE MINIMUM RAISE CEILINGS. HAVE DONE THIS BY SHOWING AN MVFR BKN DECK. HOWEVER...WOULD NOT BE SURPRISED IF SKIES SCATTER OUT...BASED ON WHAT IS HAPPENING NEAR THE COLD FRONT NOW BETWEEN RAPID CITY AND BISMARCK NORTH DAKOTA. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT LO PRES DVLPG IN THE NORTHERN PLAINS THIS MRNG TO MOVE INTO MN THIS EVENING AND THEN ONTARIO ON TUE MRNG WHILE DEEPENING. SLY GALES HAVE DVLPD AS FCST OVER ECNTRL LK SUP...AND THESE WL CONTINUE INTO TNGT BEFORE PRES GRADIENT GRDLY EASES LATE TNGT. A STRONG ARCTIC COLD FRONT WILL CROSS LAKE SUPERIOR ON TUE AS THE LO MOVES TO NEAR JAMES BAY IN THE EVNG. ANOTHER LO PRES SYS WILL DEVELOP ON THE COLD FRONT OVER THE LOWER GREAT LAKES LATE ON TUE AND MOVE INTO SE CAN AND INTENSIFY ON WEDNESDAY. GALE TO STORM FORCE W TO NW WINDS AND HEAVY FRZG SPRAY WL DVLP IN THE WAKE OF THE COLD FNT AND THE DVLPG LO ON THIS BNDRY AS ARCTIC AIR SURGES OVER LK SUP. PLAN ON THE STRONGEST WINDS FM THE KEWEENAW AND ISLE ROYALE TO THE E. AS THE LO CONTINUES NE ON THU...A HI PRES RDG WL BUILD TOWARD THE UPPER GREAT LAKES. ON FRI...A DEVELOPING LO OVER THE TENNESSEE VALLEY IS EXPECTED TO SHIFT NE TO THE EASTERN GREAT LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... WINTER STORM WATCH FROM 1 PM TUESDAY TO 7 PM WEDNESDAY MIZ001>003. WINTER STORM WATCH FROM 7 PM TUESDAY TO 7 PM WEDNESDAY MIZ006>007-085. LAKE SUPERIOR...GALE WARNING UNTIL 4 AM EST TUESDAY LSZ266-267. LAKE MICHIGAN...GALE WARNING UNTIL 1 AM EST TUESDAY LMZ248-250. && $$ UPDATE...AJ DISCUSSION...DLG AVIATION...AJ MARINE...KC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
208 PM EST MON JAN 28 2008 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO THE AREA TODAY BRINGING DRY CONDITIONS AND MILD AIR. LOW PRESSURE OVER THE MIDWEST WILL PUSH SLOWLY EAST AND PUSH LIGHT PRECIPITATION INTO THE AREA TUESDAY AND EARLY WEDNESDAY. A COLD FRONT ON WEDNESDAY WILL BRING COLDER AIR BACK INTO REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED AT 950 AM...SFC HI PRES RDG CNTRD OVER WRN NY WITH XTNSV LOW CLD DECK OVER MUCH OF THE BGM CWA. SOME CLEARING ACRS FAR ERN ZONES BUT CLDS HOLDING TUFF ALONG AND W OF I-81. ACARS DATA FROM ASCENDING BGM FLIGHT THIS MRNG SHOWED NEARLY SATURATED CONDITIONS TO JUST BLO 850 MB (SIMILAR TO 12Z BUF SNDG). WITH RDG AXIS OVERHEAD AND LGT WINDS, THINK CLDS WILL HOLD FIRM OVER THE FINGER LAKES AND CNTRL SRN TIER WELL INTO THE AFTN. CLDS MAY EVEN WORK BACK INTO THE WRN MOHAWK VLY AND CATSKILLS THIS AFTN. HOWEVER, THINK OVERALL TREND WIL BE FOR IMPVNG CONDITIONS AND WILL INDICATE PC SKIES BY MID/LATE AFTN MOST AREAS, AS SUGGESTED BY LATEST RUC PROFILES. PREV BLO... LOPRES SPINS OVER THE WRN ATLANTIC WHILE A SHARP RDG BUILDS OVER THE FCST AREA. AS USUAL...LGT NLY FLOW HAS RESULTED IN AN XTNSV SC CVR OVRNGT EVEN WHILE CI DUMPS OVER THE TOP OF THE RDG. BACK EDGE OF THE SC MAKING STEADY PROGRESS OVER WRN PA. LWR DEW PTS IN THE CNTRL AND ERN ZONES MAY HELP ERODE THE CLDS SO WILL SIMPLY FCST PTLY SUNNY SKIES FOR TODAY AS THE BACK EDGE WORKS EAST AND THE ERN CLDS ERODE IN THE DRY AIR. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... LOPRES IS OVER NW MN 00Z TUE AS THE MODELS CONT THEIR TREND OF TRACKING THE SYSTEM FURTHER WEST. UA LOW CLOSES OFF LTR TUE AS THE SYSTEM GOES NEG. REALL NO FRCG MECHANISM FOR PCPN OVER THE FCST AREA UNTIL THE COLD FNT PUSHES THRU 06Z TO 12Z WED. OPERATIONAL GFS HAS BACKED OFF ON THE EARLY QPF AND IS MORE IN LINE WITH THE NAM FOR ANY PREFNTL PCPN. STILL...BOTH THE GFS AND NAM DOP SOME LGT PCPN OVER THE AREA BEGINNING EARLY TUE...AND IF IT FALLS...TEMPS WILL BE COLD ENUF FOR SOME LGT FRZG PCPN. SO WHILE I BELIEVE THE CHANCE IS SMALL...HAVE ELECTED TO KEEP CHANCE POPS IN THE WEST FOR NOW. SOME LGT PCPN IS PSBL DURING TUE DAYLIGHT HRS BUT ONCE AGAIN THERE IS LTL TO FORCE THE PCPN. WILL STICK WITH CONTNUITY AND KEEP THE LGT PCPN DURING TUE. NEG TILT UA TROF ACCOMPANIES THE COLD FNT EARLY WED AND FINALLY SOME LIFT FOR PCPN. DEEPER...FURTHER WEST LOW HAS DELAYED THE PASSAGE OF THE COLD FNT AND ARRIVAL OF THE COLD AIR SO IN TURN HAS DELAYED THE CHG OVER TO SNOW UNTIL LTR. VERY DRY AIR BHD THE FNT WILL LIMT THE LES ACTIVITY BUT IT DOES LOOK AS THOUGH THE FLOW WILL BE FVRBL FOR SOME LES OVER THE NRN ZONES...ESP LTR WED AS THE COLD AIR BECOMES ESTABLISHED. GOOD GRADIENT AND PRESSURE RISES ON WED WILL RESULT IN VERY WINDY CONDS BHD THE FNT. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... MAIN SYSTEM DURING THE EXTENDED PERIOD WILL BE THE LOW PRESSURE SYSTEM FORECAST TO PULL NORTHEAST OUT OF THE OHIO VALLEY ON FRIDAY, TO THE NEW ENGLAND COAST FRIDAY NIGHT. CURRENT INDICATIONS ARE FOR PRECIP TO START AFTER 06Z FRIDAY FROM SOUTHWEST TO NORTHEAST. ATTM, IT LOOKS LIKE IT WILL START AS SNOW, THEN MIX DURING FRIDAY MORNING, WITH A PERIOD OF MAINLY RAIN FOR MUCH OF THE FORECAST AREA DURING THE DAY FRIDAY. MIXED PRECIP MAY WELL HOLD ON FOR MOST OF THE EVENT ACROSS NORTHEAST SECTIONS OF THE AREA, WHERE COLD AIR REMAINS ENTRENCHED. AS THE SYSTEM PULLS EAST LATER IN THE DAY, A CHANGE OVER TO SNOW OR SNOW SHOWERS IS EXPECTED FRIDAY EVENING. SOME LINGERING SHSN ACROSS LAKE EFFECT AREAS OVER THE WEEKEND, BUT OTHERWISE QUIET AS SURFACE HIGH PRESSURE EXTENDS ALONG THE ATLANTIC SEABOARD. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... STRATOCU DECK HAS BEEN SLOW TO ERODE THRU THE MORNING, WITH ONLY KRME MAKING IT OUT OF THE CLDS THUS FAR. THESE MVFR CEILINGS WILL CONTINUE THIS AFTN, WITH NAM 925 MOISTURE SHOWING MOST AREAS LOSING THE CLD COVER BETWEEN 21Z AND 23Z. AFTER THAT...VFR THRU THE NIGHT WITH WINDS BECOMING LGT SE. CLDS WILL LOWER AND THICKEN TUESDAY MRNING WITH THE APPROACH OF A WARM FRONT...TO PERHAPS MVFR WITH CHC FOR SHRA BY ABT 15Z. OUTLOOK...MVFR RESTRICTIONS LIKELY FROM TUES INTO TUES NGT WITH CDFNT. GUSTY WINDS WILL PRECEDE AND FOLLOW THIS FNT. RAPID CLEARING WITH VFR BY WED AFTN...PERSISTING THRU THURSDAY. SRN STREAM SYSTEM APRCHS THU NGT WITH MVFR/IFR CONDITIONS INTO FRIDAY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DGM NEAR TERM... SHORT TERM...DGM LONG TERM...JML AVIATION...DJP/JML
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1235 PM EST MON JAN 28 2008 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO THE AREA TODAY BRINGING DRY CONDITIONS AND MILD AIR. LOW PRESSURE OVER THE MIDWEST WILL PUSH SLOWLY EAST AND PUSH LIGHT PRECIPITATION INTO THE AREA TUESDAY AND EARLY WEDNESDAY. A COLD FRONT ON WEDNESDAY WILL BRING COLDER AIR BACK INTO REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED AT 950 AM...SFC HI PRES RDG CNTRD OVER WRN NY WITH XTNSV LOW CLD DECK OVER MUCH OF THE BGM CWA. SOME CLEARING ACRS FAR ERN ZONES BUT CLDS HOLDING TUFF ALONG AND W OF I-81. ACARS DATA FROM ASCENDING BGM FLIGHT THIS MRNG SHOWED NEARLY SATURATED CONDITIONS TO JUST BLO 850 MB (SIMILAR TO 12Z BUF SNDG). WITH RDG AXIS OVERHEAD AND LGT WINDS, THINK CLDS WILL HOLD FIRM OVER THE FINGER LAKES AND CNTRL SRN TIER WELL INTO THE AFTN. CLDS MAY EVEN WORK BACK INTO THE WRN MOHAWK VLY AND CATSKILLS THIS AFTN. HOWEVER, THINK OVERALL TREND WIL BE FOR IMPVNG CONDITIONS AND WILL INDICATE PC SKIES BY MID/LATE AFTN MOST AREAS, AS SUGGESTED BY LATEST RUC PROFILES. PREV BLO... LOPRES SPINS OVER THE WRN ATLANTIC WHILE A SHARP RDG BUILDS OVER THE FCST AREA. AS USUAL...LGT NLY FLOW HAS RESULTED IN AN XTNSV SC CVR OVRNGT EVEN WHILE CI DUMPS OVER THE TOP OF THE RDG. BACK EDGE OF THE SC MAKING STEADY PROGRESS OVER WRN PA. LWR DEW PTS IN THE CNTRL AND ERN ZONES MAY HELP ERODE THE CLDS SO WILL SIMPLY FCST PTLY SUNNY SKIES FOR TODAY AS THE BACK EDGE WORKS EAST AND THE ERN CLDS ERODE IN THE DRY AIR. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... LOPRES IS OVER NW MN 00Z TUE AS THE MODELS CONT THEIR TREND OF TRACKING THE SYSTEM FURTHER WEST. UA LOW CLOSES OFF LTR TUE AS THE SYSTEM GOES NEG. REALL NO FRCG MECHANISM FOR PCPN OVER THE FCST AREA UNTIL THE COLD FNT PUSHES THRU 06Z TO 12Z WED. OPERATIONAL GFS HAS BACKED OFF ON THE EARLY QPF AND IS MORE IN LINE WITH THE NAM FOR ANY PREFNTL PCPN. STILL...BOTH THE GFS AND NAM DOP SOME LGT PCPN OVER THE AREA BEGINNING EARLY TUE...AND IF IT FALLS...TEMPS WILL BE COLD ENUF FOR SOME LGT FRZG PCPN. SO WHILE I BELIEVE THE CHANCE IS SMALL...HAVE ELECTED TO KEEP CHANCE POPS IN THE WEST FOR NOW. SOME LGT PCPN IS PSBL DURING TUE DAYLIGHT HRS BUT ONCE AGAIN THERE IS LTL TO FORCE THE PCPN. WILL STICK WITH CONTNUITY AND KEEP THE LGT PCPN DURING TUE. NEG TILT UA TROF ACCOMPANIES THE COLD FNT EARLY WED AND FINALLY SOME LIFT FOR PCPN. DEEPER...FURTHER WEST LOW HAS DELAYED THE PASSAGE OF THE COLD FNT AND ARRIVAL OF THE COLD AIR SO IN TURN HAS DELAYED THE CHG OVER TO SNOW UNTIL LTR. VERY DRY AIR BHD THE FNT WILL LIMT THE LES ACTIVITY BUT IT DOES LOOK AS THOUGH THE FLOW WILL BE FVRBL FOR SOME LES OVER THE NRN ZONES...ESP LTR WED AS THE COLD AIR BECOMES ESTABLISHED. GOOD GRADIENT AND PRESSURE RISES ON WED WILL RESULT IN VERY WINDY CONDS BHD THE FNT. && .LONG TERM /THURSDAY THROUGH MONDAY/... FOCUS THIS PERIOD CONTINUES TO BE ON CYCLONE MOVING OUT OF THE PLAINS THROUGH THE OHIO VALLEY THURSDAY NIGHT. THIS SYSTEM WILL SPREAD PRECIPITATION INTO OUR REGION AFTER MIDNIGHT, WITH PRECIPITATION INTENSITY INCREASING ON FRIDAY. CURRENT MODEL SOUNDINGS INDICATE THE PRECIPITATION WILL BE MAINLY SNOW THURSDAY NIGHT, WITH SOME SLEET MIXING IN TOWARD MORNING... PARTICULARLY OVER SOUTHERN HALF OF REGION. FRIDAY WILL SEE WARM AIR CONTINUE TO SURGE NORTHWARD AHEAD OF COLD FRONT, CHANGING PTYPE FOR SOUTHERN HALF OF FORECAST AREA TO RAIN. A MIX WILL HOLD ON OVER THE NORTHEAST WHERE COLD AIR REMAINS ENTRENCHED. ONCE THE COLD FRONT PULLS THROUGH DURING THE AFTERNOON, EXPECT THE MAIN PTYPE TO GO BACK OVER TO SNOW. BIGGEST CONCERN WITH THIS EVENT WILL BE MIXED PRECIP, AS THERE APPEARS TO BE ENOUGH WARM AIR IN THE MODELS TO PRECLUDE STRONG SNOW GROWTH. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... STRATOCU DECK HAS BEEN SLOW TO ERODE THRU THE MORNING, WITH ONLY KRME MAKING IT OUT OF THE CLDS THUS FAR. THESE MVFR CEILINGS WILL CONTINUE THIS AFTN, WITH NAM 925 MOISTURE SHOWING MOST AREAS LOSING THE CLD COVER BETWEEN 21Z AND 23Z. AFTER THAT...VFR THRU THE NIGHT WITH WINDS BECOMING LGT SE. CLDS WILL LOWER AND THICKEN TUESDAY MRNING WITH THE APPROACH OF A WARM FRONT...TO PERHAPS MVFR WITH CHC FOR SHRA BY ABT 15Z. OUTLOOK...MVFR RESTRICTIONS LIKELY FROM TUES INTO TUES NGT WITH CDFNT. GUSTY WINDS WILL PRECEDE AND FOLLOW THIS FNT. RAPID CLEARING WITH VFR BY WED AFTN...PERSISTING THRU THURSDAY. SRN STREAM SYSTEM APRCHS THU NGT WITH MVFR/IFR CONDITIONS INTO FRIDAY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DGM NEAR TERM... SHORT TERM...DGM LONG TERM...DJP AVIATION...DJP/JML
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
940 PM CST MON JAN 28 2008 .DISCUSSION... WATER VAPOR LOOP SHOWS UPPER LEVEL TROUGH EXTENDED FROM WESTERN MT TO SOUTHERN NV MOVING EAST ABOUT 25 KNOTS. WATER VAPOR LOOP ALSO INDICATED A SHORT WAVE OVER WESTERN IA MOVING NORTHEAST. RAIN WAS OCCURRING OVER EASTERN MN WITH THIS FEATURE. SURFACE LOW PRESSURE NEAR INL AND IS FORECAST TO MODESTLY DEEPEN AND MOVE NEAR LS BY MORNING. HIGH PRESSURE OVER SOUTHERN BC WILL ALSO INTENSIFY A BIT AND MOVE ALONG THE BC/AB BORDER BY MORNING. GOOD PRESSURE GRADIENT WILL OCCUR ACROSS THE AREA OVERNIGHT. MODEL SOUNDINGS AND AN EAST WEST CROSS SECTION INDICATES A NEARLY ADIABATIC LOW LEVEL LAYER FOR TONIGHT AND SHOULD MAKE FOR GOOD MIXING AND MAINTAINING WINDY CONDITIONS. RADAR INDICATED LIGHT SNOW OVER MUCH OF EASTERN ND MOVING EAST ABOUT 15 KNOTS. SNOW WAS OCCURRING ALONG A COLD FRONT ALOFT. WINDS HAVE INCREASED ACROSS EASTERN ND WITH GUSTS TO 40 KNOTS AT DVL. EXPECT NORTHWEST WINDS TO INCREASE WITH ACROSS THE REST OF THE FORECAST AREA TONIGHT AS PRECIPITATION BAND SWEEPS ACROSS THE AREA. MESOSCALE ANALYSIS SHOWS SURFACE LOWEST MIXING RATIOS WERE MOVING INTO THE WESTERN DAKOTAS. PRESSURE RISE CENTER OVER MT WAS MOVING SOUTHEAST INTO CENTRAL SD. RUC AND NAM HANDLED WITH THE PRESSURE RISES BEST. TAMDAR SOUNDINGS INDICATE NAM WAS A LITTLE COLDER AND WAS BETTER WITH LOW LEVEL TEMP FIELD THAN THE RUC OR THE GFS. WILL USE THE RUC AND NAM FOR TONIGHT. GOING ADVISORIES AND WARNINGS LOOK GOOD. WILL UPDATE ZONES. && .PREVIOUS DISCUSSION.../ISSUED 245 PM CST MON JAN 28 2008/ MAIN FORECAST CHALLENGE IS WHAT TO TRANSITION TO WITH OUR WINTER STORM WATCH HEADLINE. MODELS HAVE BEEN PRETTY CONSISTENT WITH THIS SYSTEM...TRENDING DRIER BUT STILL WITH PLENTY OF COLD/WIND. WILL STICK PRETTY CLOSE TO THE GFS TODAY...ALTHOUGH WILL TREND BACK FROM THE 12Z GFS RUNS HIGHER QPF AMOUNTS. TONIGHT/TUE...SFC LOW AT 20Z IS SOMEWHERE BETWEEN KJMS AND KABR. KFAR/KJMS HAVE SWITCHED FROM SOUTH WINDS TO A NORTHERLY COMPONENT. COLD PUSH AND STRONGER WINDS ARE NOW INTO THE WESTERN HALF OF ND AND WILL PUSH INTO THE FA TONIGHT. BATCH OF MOSTLY MID LEVEL ECHOES ARE NOW MOVING INTO THE SOUTHERN HALF OF MN...AND THERE HAVE BEEN SOME SPRINKLES OR VERY LIGHT RAIN WITH THIS. THIS WILL NOT AFFECT OUR SOUTHEAST FA AT ALL...SO WILL NOT HAVE TO WORRY ABOUT ANY FREEZING OR LIQUID PCPN FOR THIS EVENT. THERE IS ANOTHER BATCH OF ECHOES ON RADAR IN WESTERN ND...AND THIS SHOULD CONTINUE TO PUSH EAST AND GIVE A LITTLE LIGHT SNOW TO OUR FA. AS FAR AS HOW TO TRANSITION FROM OUR CURRENT WINTER STORM WATCH...HAVE ELECTED TO GO WITH A WINTER WEATHER ADVISORY AT FIRST. WILL HAVE THE COMBINATION OF SOME LIGHT SNOW/BLOWING SNOW AND FALLING TEMPS... LEADING TO SOME WIND CHILL ISSUES. ALL THESE PARAMETERS SHOULD STAY IN ADVISORY CRITERIA FOR MOST OF THE NIGHT. THERE COULD BE SOME LOWER VSBYS INITIALLY...BUT AM NOT EXPECTING A DURATION OF VSBYS LESS THAN A QUARTER MILE. AS THE COLDER AIR WORKS INTO THE KDVL REGION TOWARD MORNING...WIND CHILL VALUES START TO GET INTO WIND CHILL WARNING CRITERIA. THEREFORE WILL ISSUE A DOUBLE HEADLINE PRODUCT AND TRANSITION FROM THE WINTER WEATHER ADVISORY TO A WIND CHILL WARNING FOR PORTIONS OF THE FA TOWARD MORNING. WILL KEEP ALL HEADLINES VALID UNTIL 00Z WED. TUE NIGHT...THERE COULD BE A PERIOD OF TIME YET INTO TUE NIGHT WHERE WIND CHILL HEADLINES WILL STILL BE NEEDED. WILL HOLD OFF ON EXTENDING THE PLANNED HEADLINES FOR NOW TO KEEP THINGS FROM GETTING TOO CONFUSING. WILL LEAVE THIS FOR LATER SHIFTS. WED/THU...HIGH PRESSURE WILL AFFECT THE FA FOR A PORTION OF WED... BUT THIS WILL SHIFT OFF TO THE EAST ON THU. FORECAST CHALLENGE WILL TRANSITION TO MAINLY TEMPS...AND THESE GREATLY AFFECTED BY CLOUD TRENDS. .LONG TERM [FRI-MON]... DECENT AGREEMENT AMONG GFS/CANADIAN/ECMWF MODELS WITH POSITION/SPEED OF SFC LOW MOVING ACROSS SRN CANADA LATE THU NIGHT INTO EARLY SAT MORNING. BIGGEST CHALLENGE I SEE AS SYSTEM APPROACHES IS TEMPS THU NIGHT AND FRI. WITH SOUTHERLY FLOW SETTING UP BY 00Z FRIDAY...I INCREASED MIN TEMPS FOR THU NIGHT. MODELS CONSISTENT IN SHOWING A BAND OF CLOUDS ACROSS SRN CANADA AND JUST INTO OUR NORTHERN ZONES. WITH H850 TEMPS PROGGED TO BE AROUND 20 F IN THE NORTHEAST...COUPLED WITH FAIRLY DECENT SOUTHERLY FLOW...SHOULD HAVE ENOUGH MIXING TO KEEP US FROM DROPPING MUCH BELOW NEG 10 F...PROBABLY WARMER. MEX GUIDANCE KEEPS MOST OF FA IN SINGLE DIGITS ABOVE ZERO. THUS STILL WELL BELOW GUIDANCE...BUT ABOUT 5 DEG WARMER THAN PREVIOUS GRIDS SHOWED AND WARMER THAN MOST SURROUNDING OFFICES. INTRODUCED A SLIGHT CHANCE OF LIGHT SNOW BEHIND THE SYSTEM FROM NOON FRIDAY TO MIDNIGHT SATURDAY. && .AVIATION... MOSTLY MVFR CIGS HAVE BEEN ACROSS NORTHEAST ND THIS EVENING. EXPECT CIGS AND VISIBILITIES TO BECOME IFR FOR A COUPLE HOURS AT GFK AND FAR AS WINDS INCREASE AND BAND OF PRECIPITATION MOVES THROUGH THE RED RIVER VALLEY. CIGS MAY RISE TO VFR/MVFR EARLY TUE MORNING THEN FALL BACK INTO MVFR CONDITIONS FOR LATER TONIGHT AND TUE. EXPECT SIMILAR CONDITIONS AT BJI BUT A COUPLE HOURS BEHIND GFK AND FAR. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR NDZ008- 016-027-029-030-039-049-052-053. WIND CHILL WARNING FROM 6 AM TO 6 PM CST TUESDAY FOR NDZ008-016- 027-029-030-039-049-052-053. WINTER WEATHER ADVISORY UNTIL 3 AM CST TUESDAY FOR NDZ006-007- 014-015-024-026-028-038-054. WIND CHILL WARNING FROM 3 AM TO 6 PM CST TUESDAY FOR NDZ006-007- 014-015-024-026-028-038-054. MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR MNZ001>004- 007-029. WIND CHILL WARNING FROM 6 AM TO 6 PM CST TUESDAY FOR MNZ001>004- 007-029. WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR MNZ005-008- 013>015-022-027-030-031-040. WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CST TUESDAY FOR MNZ006- 009-016-017-023-024-028-032. && $$ HOPPES
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1103 AM CST MON JAN 28 2008 .UPDATE...ADJUSTED PRECIPITATION CHANCES AND TEMPERATURES FOR TODAY. 12Z SOUNDINGS ACROSS THE REGION AND UPSTREAM WERE SHOWING A DEEP DRY LAYER BELOW 700MB...500MB IN SOME LOCATIONS. RADAR LOOP SHOWED SOME WEAK RETURNS BUT IT APPEARS THAT IT IS PICKING UP MID CLOUDS. SOME LIGHT DRIZZLE SHOWED UP ON OBSERVATIONS LATE THIS MORNING IN WESTERN ILLINOIS...ONE SITE HAD 10SM -DZ CLR AND ANOTHER 10SM -DZ SCT070 OVC090. SOME RAIN WAS REPORTED ON OBSERVATIONS AROUND SAINT LOUIS...BUT PREVAILING CONDITIONS THERE AT THE TIME WERE UNRESTRICTED VISIBILITY WITH MIDDLE CLOUDS. MODELS NOT IN AGREEMENT REGARDING QPF. COMPARISON AMONG 12Z NAM...NGM AND GFS RANGED FROM NOTHING AT ALL THIS AFTERNOON TO QPF ACROSS THE ENTIRE AREA. BASED ON CURRENT CONDITIONS AND TRENDS...HAVE DECIDED TO ONLY GO WITH NOTHING IN VILAS COUNTY AND CHANCE POPS IN THE SOUTH AND EAST...WITH SLIGHT CHANCE BETWEEN THE TWO. INCREASED MAX TEMPERATURES FOR THIS AFTERNOON...BUT SNOW PACK MAY MAKE IT DIFFICULT TO MIX VERY DEEP. WARMEST TEMPERATURES LATE THIS MORNING WERE IN THE SOUTHERN AND NORTHWEST PARTS OF THE FORECAST AREA WITH COOLER READINGS BETWEEN THE TWO. HAVE SMOOTHED HIGH TEMPERATURES IN THE GRIDS AND ZONES. MG && .PREV DISCUSSION...ISSUED AT 455 AM CST MON JAN 28 2008... SHORT TERM....TODAY THROUGH TUESDAY...PCPN TRENDS...EFFECTS OF ARCTIC COLD FRONTAL PASSAGE AND WINTER WX HEADLINES ARE THE FOCUS DURING THIS PERIOD. HAVE PULLED POPS FROM THE MORNING FCST...AS MODELS CONTINUE TO DELAY THE ONSET OF PCPN OVER C/NE WI...AND UPSTREAM OBS SHOW MAINLY HIGH CLOUDS UPSTREAM. WILL KEEP LIKELY POPS FOR THIS AFTERNOON...WITH FAIRLY LGT QPF. GIVEN THE LATER ARRIVAL TIME AND EXPECTED HIGH TEMPS IN THE UPPER 30S TO LOWER 40S...WILL JUST MENTION LIGHT RAIN ATTM. TONIGHT...DEEPER SATURATION OCCURS DURING THE EVG HOURS... COINCIDENT WITH THE ARRIVAL OF A S/W TROF AND SOME JET ENERGY. DYNAMIC/EVAPORATIVE COOLING NEARLY WIPE OUT THE WARM LYR ALOFT OVER NORTHERN WI DURING THE EARLY EVG...OPENING UP THE POSSIBILITY OF A MIX OF RAIN/SNOW/SLEET. A DRY SLOT ARRIVE AFTER MIDNIGHT... LIKELY RESULTING IN A DECREASE IN PCPN OVERNIGHT. HAVE REDUCED POPS TO CHC CATEGORY...AND MENTIONED MAINLY LGT RAIN...DRIZZLE AND AREAS OF FOG. THE LEADING EDGE OF THE ARTIC BOUNDARY MAY SLIP INTO OUR NW COUNTIES OVERNIGHT...LEADING TO THE POSSIBILITY OF SOME FZDZ IN NC/C WI. ON TUES...THE POWERFUL ARCTIC FRONT IS EXPECTED TO SHIFT THROUGH THE FA DURING THE 12-18Z PERIOD...WITH THE COLDEST AIR SURGING INTO THE RGN DURING THE AFTERNOON. A MIX OF LIGHT RAIN OR FREEZING RAIN WILL OCCUR DURING THE MORNING...FOLLOWED BY SNOW DURING THE AFTERNOON AS DEEP FRONTOGENETIC FORCING AND UPPER DIVG AHEAD OF A STG NEGATIVELY-TILTED S/W TROF ARRIVE. EXPECT ACCUMS OF 1-3 INCHES OF POWDERY SNOW BY EVG. COMBO OF STG CAA AND INCREASING ISALLOBARIC GRADIENT WILL CAUSE A SIGNIFICANT INCREASE IN WEST WINDS DURING THE AFTERNOON...WITH GUSTS TO 35-45 MPH CAUSING CONSIDERABLE BLOWING/DRIFTING SNOW. TEMPS WILL FALL SHARPLY DURING THE AFTERNOON. GIVEN THE COMBINED THREAT OF FREEZING PCPN...SOME MODEST SNOW ACCUMS...STG WINDS AND ASSOC BLOWING SNOW AND FALLING TEMPS...HAVE OPTED TO ISSUE A WINTER WEATHER ADVSY FOR THE ENTIRE CWA THROUGH TUES NGT. LONG TERM...TUESDAY NIGHT THROUGH NEXT SUNDAY WINDY CONDITIONS ALONG WITH SNOW AND BLOWING SNOW WILL CREATE HAZARDOUS CONDITIONS FOR AIRCRAFT OR BY CAR. PER COORDINATION WITH SURROUNDING OFFICES AND WITH THE SHORT TERM FORECASTER... MANY DIFFERENT HEADLINE OPTIONS WERE DISCUSSED DUE TO THE DIFFERENT TYPES OF PRECIPITATION ON TUESDAY MORNING...THEN SNOW AND CONSIDERABLE BLOWING AND DRIFTING SNOW AS THE ARCTIC COLD FRONT RACES ACROSS THE AREA TUESDAY AFTERNOON AND TUESDAY EVENING. DECIDED TO GO WITH A WINTER WEATHER ADVISORY FOR MUCH OF TUESDAY UNTIL 12Z WEDNESDAY. FOR MY PART OF THE FORECAST...WILL BE DEALING WITH BAND OF SNOW EXITING THE REGION ALONG WITH CONSIDERABLE BLOWING AND DRIFTING OF THE SNOW. WIND GUSTS OVER 40 MPH WILL CREATE NEAR BLIZZARD CONDITIONS AT TIMES. ALONG WITH THE WHITE OUT CONDITIONS...EXPECTING AREA ROADS TO FREEZE UP DUE TO THE RAINFALL EARLY IN THE DAY AND THEN SNOW AND BLOWING SNOW DURING THE AFTERNOON ALONG WITH TEMPERATURES FALLING WELL BELOW FREEZING. THE EVENING COMMUTE ACROSS NORTHEAST WISCONSIN COULD BE VERY TREACHEROUS DESPITE SANDING AND SALTING OF AREA ROADS. THE SNOW SHOULD DIMINISH QUICKLY TO SCATTERED FLURRIES TUESDAY EVENING. AREAS OF BLOWING SNOW SHOULD CONTINUE OVERNIGHT. LATER TUESDAY NIGHT...WIND CHILL READINGS WILL APPROACH WARNING CRITERIA...35 BELOW ZERO OR LOWER ACROSS CENTRAL AND NORTH CENTRAL WISCONSIN. WIND CHILL ADVISORY CRITERIA SHOULD BE MET OVER THE REMAINDER OF NORTHEAST WISCONSIN WITH WINDS OF 25 TO 35 BELOW ZERO. ALSO HAVE LOWER MINIMUM TEMPERATURES SEVERAL DEGREES ON WEDNESDAY...HAVE UNDERCUT GUIDANCE BY 5 DEGREES AND CUT AROUND 10 DEGREES OFF CURRENT HIGHS. DESPITE PARTLY CLOUDY CONDITIONS... TEMPERATURES WILL STRUGGLE INTO THE SINGLE DIGITS ABOVE ZERO. DO NOT PUT AWAY THE SNOW SHOVELS. AN ACTIVE PATTERN IS SETTING UP LATER THIS WEEK...AND MODELS SUGGESTING A SIGNIFICANT SNOWFALL BEYOND THE FORECAST PERIOD EARLY NEXT WEEK. RETURN FLOW SETS UP WEDNESDAY NIGHT AND MODELS ARE STRUGGLING WITH LOW LEVEL MOISTURE. HAVE INCREASED SNOW CHANCES OVER THE SOUTH WEDNESDAY NIGHT INTO THURSDAY NIGHT. DEPENDING ON THE LOW LEVEL MOISTURE...COULD BE SEVERAL INCHES OF SNOW DURING THIS PERIOD. A SECONDARY STORM IS EXPECTED TO DEVELOP AND MOVE TOWARDS THE GREAT LAKES REGION. THE 00Z ECMWF TONIGHT WOULD SUGGEST THAT A WINTER STORM WATCH WILL NEEDED ACROSS NORTHEAST WISCONSIN AS THIS MODEL TRACKS THE SYSTEM FURTHER WEST THAN THE CANADIAN/GFS. MY HUNCH IS THAT THE GFS/CANADIAN WILL TREND FURTHER WEST ON LATER MODEL RUNS. PLENTY OF TIME TO SORT THE DETAILS ON THIS FEATURE AND WILL BE WATCHING IT CLOSELY OVER THE NEXT SEVERAL DAYS. THE OTHER SIGNIFICANT STORM WILL OCCUR NEXT MONDAY INTO TUESDAY. BOTH THE ECMWF AND GFS ARE CRANKING OUT 1.00 TO 2.00 INCHES OF LIQUID QPF. IF THIS FALLS AS SNOW...THIS WOULD EQUATE TO 10 TO 20 INCHES OF SNOW. THE GFS IS FURTHER WEST AND WOULD SUGGEST SOME RAIN OVER THE SOUTHEAST PORTION OF THE FORECAST AREA. ANOTHER SYSTEM TO WATCH OVER THE NEXT WEEK. THE ECMWF WOULD SUGGEST ALL SNOW. AVIATION...ASIDE FROM SOME MVFR VSBYS IN LIGHT FOG THIS MORNING... EXPECT VFR CONDITIONS TO PREVAIL UNTIL MID-LATE AFTERNOON...WHEN LIGHT RAIN AND ASSOC MVFR CONDITIONS ARE EXPECTED TO DEVELOP. EXPECT CIGS/VSBYS TO LOWER TONIGHT DUE TO RAINFALL AND INCREASING DEW POINTS OVER A DEEP SNOWPACK. SOME FZDZ/LIGHT FZRA IS PSBL OVER PARTS OF C/NC WI LATE TONIGHT. LLWS WILL CONTINUE TODAY INTO TONIGHT...THEN DIMINISH OVERNIGHT AS WINDS ALOFT DECREASE. MARINE...A GALE WARNING WILL BE IN EFFECT THROUGH TUESDAY NIGHT. SOUTH GALES WILL DEVELOP THIS MORNING AND CONTINUE INTO TONIGHT. WINDS WILL SUBSIDE A BIT DURING THE DAY ON TUESDAY...THEN INCREASE TO GALE FORCE FROM THE WEST LATER TUESDAY INTO TUES NGT AS AN ARCTIC FRONT MOVES THROUGH. WILL NEED TO MONITOR THE POTENTIAL FOR A BRIEF PERIOD OF STORM FORCE GUSTS TUESDAY EVG AS STG CAA AND THE CORE OF STRONGEST PRESSURE RISES MOVES THROUGH. && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 12 PM TUESDAY TO 6 AM CST WEDNESDAY FOR WIZ022-038>040-048>050-073-074. WINTER WEATHER ADVISORY FROM 9 AM TUESDAY TO 6 AM CST WEDNESDAY FOR WIZ005-010>013-018>021-030-031-035>037-045. && $$ TK/RE
AREA FORECAST DISCUSSION
NWS CHICAGO IL
319 AM CST TUE JAN 29 2008 .DISCUSSION... 319 AM CST MAIN FORECAST CONCERN THIS MORNING IS PASSAGE OF ARCTIC FRONT TODAY...ALONG WITH SNOW AND VERY WINDY CONDITIONS CREATING VERY HAZARDOUS TRAVEL CONDITIONS LATER TODAY INTO TONIGHT. A WINTER STORM WARNING WILL REMAIN IN EFFECT. AT 08Z...SURFACE COLD FRONT EXTENDS FROM NORTH CENTRAL WISCONSIN THROUGH CENTRAL IOWA...WITH PRESSURE RISES ON THE ORDER OF 6 TO 8 MB/3 HOURS BEHIND THIS FRONT. STRONG LOW/MID LEVEL SOUTHWESTERLY FLOW WILL CONTINUE THIS MORNING IN ADVANCE OF THIS FRONT ALLOWING FOR QUITE MILD CONDITIONS THIS MORNING. FRONT MAY TEND TO SLOW JUST A BIT THIS LATER THIS MORNING/EARLY THIS AFTERNOON AS AN UPPER LEVEL SHORT WAVE DIGGING INTO THE NORTHERN PLAINS SHOULD ALLOW FOR LOW LEVEL WINDS TO BACK SLIGHTLY MORE SOUTH SOUTHWEST. WATER VAPOR IMAGERY ALSO HIGHLIGHTS A SHORT WAVE TROUGH MOVING ACROSS WESTERN KANSAS WHICH SHOULD TRACK INTO NORTHERN ILLINOIS TOWARD MIDDAY...WITH A STRONGER SHORT WAVE ON ITS HEELS MOVING OUT OF THE ROCKIES. FORECAST SOUNDINGS INDICATE SOME FAIRLY STEEP MID LEVEL LAPSE RATES OVERSPREADING THE AREA TODAY IN ADVANCE OF THE ARCTIC FRONT...ON THE ORDER OF 7 DEG C/KM. ELEVATED CAPES DO INCREASE TO AROUND 500 J/KG BY MID MORNING...AND GIVEN APPROACHING SHORT WAVES ...WILL MAINTAIN LIKELY POPS FOR RAIN SHOWERS THIS MORNING AND KEEP THE MENTION OF THUNDER GOING THIS MORNING. SPC DAY 1 CONVECTIVE OUTLOOK DOES TAKE SLIGHT RISK OF SEVERE JUST SOUTH OF THE CWA. ALTHOUGH INSTABILITY IS ELEVATED IN NATURE...MAY HAVE TO MONITOR WIND GUSTS WITH ANY CONVECTIVE ELEMENTS THAT DEVELOP ACROSS THE AREA GIVEN THE STRONG UNIDIRECTIONAL WIND PROFILE. FOCUS THIS AFTERNOON WILL THEN SHIFT TO WEATHER BEHIND THE ARCTIC FRONT. INHERITED FORECAST STILL SEEMS REASONABLE IN TERMS OF TIMING PRECIP TYPE CHANGEOVERS. STRONGER AFOREMENTIONED VORT MAX ACROSS THE ROCKIES WILL LIFT INTO THE AREA LATER THIS AFTERNOON WHICH SHOULD ALLOW FOR PRECIP ENHANCEMENT WITH THE ARCTIC BOUNDARY. FORECAST AREA ALSO WILL BE SETUP IN FAVORABLE LEFT EXIT REGION OF UPPER JET STREAK CUTTING THROUGH THE BASE OF THIS TROUGH ENHANCING UPWARD VERTICAL MOTIONS. DID INCLUDE A BRIEF PERIOD OF SLEET DURING THE PRECIP CHANGEOVER AS WRF/GFS FORECAST SOUNDINGS MAINTAIN A WEAK ELEVATED WARM LAYER ATOP SHALLOW ARCTIC AIR MASS THIS AFTERNOON. OF MORE CONCERN WILL BE COMBINATION OF SNOW AND WIND BEHIND THIS BOUNDARY. STRONG ISALLOBARIC COMPONENT/COLD ADVECTION SHOULD SUPPORT GUSTS TO 45 TO 50 MPH THIS AFTERNOON INTO EARLY THIS EVENING. HAVE KEPT SNOW ACCUMS IN THE 1 TO 3 INCH RANGE ACROSS THE AREA FROM THIS AFTERNOON THROUGH EARLY THIS EVENING GIVEN FAIRLY SHARP DRYING BEHIND THIS BOUNDARY...BUT THE COMBINATION OF SNOW AND THESE WINDS WILL CREATE EXTREMELY HAZARDOUS TRAVEL CONDITIONS...AND VERY LOW VISIBILITIES LESS THAN A QUARTER OF A MILE AT TIMES. WILL KEEP WINTER STORM WARNING HEADLINE IN EFFECT...AND JUST ALTER THE BEGINNING TIME FOR NORTHWEST INDIANA COUNTIES TO 00Z WITH EXPECTED TIMING OF THE FRONT. SNOW SHOULD DIMINISH TOWARD MIDNIGHT WITH CLEARING SKIES OVERNIGHT...BUT WINDS WILL REMAIN STRONG OVERNIGHT RESULTING IN CONTINUED BLOWING AND DRIFTING SNOW PROBLEMS AND REDUCED VISIBILITIES. WIND CHILLS ALSO DROP OFF INTO THE 15 TO 25 BELOW ZERO RANGE OVERNIGHT...ESPECIALLY ACROSS THE NORTHERN HALF OF THE FORECAST AREA. AREAS OF BLOWING SNOW WILL PERSIST INTO EARLY WEDNESDAY...BUT WINDS SHOULD SUBSIDE FAIRLY RAPIDLY BY LATE MORNING AS SFC RIDGE AXIS SETTLES OVER THE AREA. MID LEVEL CLOUDINESS WILL INCREASE DURING THE AFTERNOON AND EVENING AS MID LEVEL WAA BECOMES MORE PRONOUNCED IN RESPONSE TO NEXT UPPER LEVEL SHORT WAVE TROUGH OF INTEREST DIGGING INTO THE CENTRAL PLAINS. AT THIS TIME...CURRENT THINKING IS A SOLUTION SLIGHTLY SLOWER THAN 00Z OPERATIONAL GFS MIGHT BE THE BEST APPROACH WITH THE EVOLUTION OF THIS WAVE...AS NCEP ENSEMBLE MEANS AND ECMWF HAVE TRENDED SLOWER. ALTHOUGH MUCH UNCERTAINTY REMAINS REGARDING THE TRACK OF THIS SYSTEM...THIS SYSTEM WILL NEED TO BE WATCHED AS IT LIFTS NORTHEAST THURSDAY INTO FRIDAY WITH A POTENTIAL FOR HEAVY SNOW. CURRENT INDICATIONS WOULD POINT TOWARD SOUTHEAST HALF OF THE FORECAST AREA AS HAVING THE GREATEST CHANCE OF SIGNIFICANT SNOW...BUT WILL HAVE TO FINE TUNE THIS ASSESSMENT OVER THE NEXT DAY OR SO. WILL MAINTAIN LIKELY POPS ON FRIDAY FOR SNOW GIVEN PREFERENCE OF A SLOWER SOLUTION...AND ALSO DID INTRODUCE CHANCE POPS FOR -SN ON THURSDAY AFTERNOON ACROSS FAR NORTH CENTRAL ILLINOIS WITH GFS ISENTROPIC PROGS INDICATING SOME LIGHT SNOW POSSIBLE. NO CHANGES WERE MADE TO THE FORECAST POST FRIDAY...WITH A RELATIVELY QUIET PERIOD IN STORE FOR THE WEEKEND. LATEST GFS DOES INDICATE ANOTHER RAINY SYSTEM FOR EARLY NEXT WEEK...BUT ENOUGH DISCREPANCIES PERSIST IN THE MEDIUM RANGE MODELS TO KEEP LOW CHANCE POPS FOR RA/SN AT THIS TIME FOR MONDAY. MARSILI && .AVIATION... 0600 UTC TAFS THE ACARS SOUNDING AT 0316 UTC SHOWS AN INVERSION WITH 54 KNOT WIND AT 3000 FT. THERE WILL BE GUSTS TO 30 KNOTS AT SURFACE OVERNIGHT. WILL KEEP AN EYE ON THE WIND OVERNIGHT. IF THE WIND DECREASES MORE THERE MAY BE LOW LEVEL WIND SHEAR. ADDED SOME FOG IN THE FORECAST BUT IT MAY NOT FORM BECAUSE OF THE WIND. THE FRONT WILL MOVE THROUGH AROUND 23 UTC IN CHICAGO AND 20 UTC IN ROCKFORD. THERE WILL BE SNOW BEHIND THE FRONT AND RAIN AND SNOW MIXED AHEAD OF THE FRONT. THE WIND WILL BE AT LEAST 20 TO 25 KNOTS FROM THE NORTHWEST LATE TUESDAY. SNOW AND BLOWING SNOW IS EXPECTED AFTER 20 UTC ACROSS ROCKFORD AND 23 UTC ACROSS CHICAGO AND GARY. WE USED THE LOCAL WRF AND THE NATIONAL WRF MODELS FOR GUIDANCE. && .MARINE... 258 AM CST DEEP LOW PRESSURE LIFTING NORTHEAST ACROSS ONTARIO THIS MORNING...WITH ARCTIC COLD FRONT TRAILING THROUGH THE PLAINS. THIS FRONT WILL PUSH EAST ACROSS LAKE MICHIGAN THIS AFTERNOON AS ANOTHER WAVE OF LOW PRESSURE RIPPLES NORTHEAST ALONG THE FRONT AND INTO THE GREAT LAKES BY TONIGHT. INTENSE SURFACE PRESSURE GRADIENT AND STRONG LOW LEVEL COLD ADVECTION EXPECTED TO RESULT IN 40-45 KNOT GALES DEVELOPING FROM WEST/NORTHWEST BEHIND FRONT LATER TODAY...WITH AIR TEMPERATURES FALLING INTO THE SINGLE DIGITS OVER THE LAKE TONIGHT. HEAVY FREEZING SPRAY WILL POSE STRONG ICING THREAT TONIGHT AND WEDNESDAY AS STRONG WINDS COMBINE WITH BITTER COLD...AND HAVE ISSUED HEAVY FREEZING SPRAY WARNING FROM 6 PM CST TONIGHT THROUGH THE DAY WEDNESDAY. GALES WILL GRADUALLY DIMINISH DURING THE DAY WEDNESDAY AS SECOND LOW ALSO MOVES NORTH TOWARD JAMES BAY...AND HIGH PRESSURE RIDGE BUILDS FROM PLAINS INTO GREAT LAKES AREA WEDNESDAY NIGHT. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING FROM NOON TODAY TO 12 PM CST WEDNESDAY FOR ILZ003>006-008-010>014-019>023-032-033-039. IN...WINTER STORM WARNING FROM 6 PM CST /7 PM EST/ THIS EVENING TO 12 PM CST /1 PM EST/ WEDNESDAY FOR INZ001-002-010-011-019. LM...HEAVY FREEZING SPRAY WARNING FROM 6 PM THIS EVENING TO 6 PM CST WEDNESDAY FOR LMZ777-779. GALE WARNING UNTIL 12 PM CST WEDNESDAY FOR LMZ740>745-777-779. HEAVY FREEZING SPRAY WARNING FROM 6 PM THIS EVENING TO 12 PM CST WEDNESDAY FOR LMZ740>745. && $$ WFO LOT
AREA FORECAST DISCUSSION
NWS CHICAGO IL
258 AM CST TUE JAN 29 2008 .DISCUSSION... 310 PM CST FOCUS REMAINS ON DEEPENING TROF IN PLAINS OVERNIGHT WITH MINOR WAVES TRAVELING NE ON STRONG 60 KT LL JET AND FEEDING HEAT AND MSTR INTO THE MS VLY AND GREAT LAKES. LATEST WAVE OF RAIN SHUD BE DEPARTING TO THE EAST LATE THIS AFTN AND EVENING. NOT MUCH WAVE ACTIVITY SWINGING THRU AFTER THIS EVENING BUT AM KEEPING A MINIMAL CHANCE OF RAIN IN AREA OVERNIGHT WITH STRONG JET FEEDING MSTR INTO AREA. SFC FNT ASSOC WITH UPR TROF SWINGS ACRS MS RVR ARND DAYBREAK WHILE STILL DEEPENING...THEN INTO NE IL IN THE EARLY AFTN...THRU NW INDIANA BY SUNSET. WHILE RAIN CHANCES STILL VALID AHEAD OF COLD FRONT...MAIN ACTIVITY OF CONCERN WILL BE POST FRONTAL. HUGE PRESSURE RISES A FEW HOURS BEHIND FROPA SHUD ACCOMPANY A QUICK DROP IN DAYTIME TEMPERATURES USHERED IN BY STORM FORCE WINDS OF 45 TO 50 MPH. POST FRONTAL PCPN MAY START OFF AS A RAIN AND SNOW MIX BUT QUICKLY TURN OVER TO SNOW TUESDAY EVENING. MELTING SNOW SHUD TAKE LITTLE TIME TO FREEZE WITH THE BLAST OF COLD ARCTIC WIND...CAUSING ROADS TO BECOME SLICK VERY FAST. AN INCH OR TWO OR MAYBE 3 INCHES OF NEW SNOW ON TOP OF THIS WILL MAKE TRAVEL EVEN WORSE. THIS ADDITIONAL SNOW OF COURSE WILL BE BLOWN SIDEWAYS AND LOWERING VISIBILITY TO A QUARTER MILE OR LESS WILL BE MAKING ROAD CLEANUP IMPOSSIBLE. PRESENTLY AM LOOKING AT 2 TO 3 INCHES OF NEW SNOW NORTH OF I-88 WITH 1 TO 2 INCHES FROM I-88 SOUTH TO I-80 AND AN INCH OR LESS SOUTH OF I-80. LUCKILY THIS PCPN WILL BE OUT OF HERE QUICKLY OVERNIGHT TUES NGT BUT STILL BLOWING INTO THE MORNING HOURS WEDNESDAY. NIGHTTIME LOWS TUESDAY NIGHT WILL DROP INTO THE MINUS AND PLUS SINGLE DIGITS FROM I-80 NORTH...TO THE LOW DOUBLE DIGITS SOUTH.. WITH HIGH WINDS STILL BLOWING THRU THE NIGHT...WIND CHILLS WILL DROP INTO ADVISORY CATEGORY IN THE NORTH AT -20 TO -25F. HEADLINES WILL PROBABLY BE POSTED FOR ADVISORIES BY TMRW MRNG AND MAY EITHER BE MULTIPLE HEADLINES OR LIMITED TO A SINGLE HEADLINE TO INCORPORATE HIGH WINDS...BLINDING SNOW...AND WIND CHILLS. THIS WILL BE WINTER AT ITS WORST...THROWING EVERYTHING IT HAS AT US. WARMUP WILL BE RATHER QUICK INTO THE TEENS AND 20S FOR WEDNESDAY INTO THURSDAY AHEAD OF ANOTHER DEEPENING TROF. THIS ONE IS HEADED SOUTH OF THE AREA ACROSS THE SRN PLAINS. BROAD UPPER RIDGING OCCURS OVER THE MIDDLE OF THE CONUS THU IN RESPONSE TO NEXT TROF DROPPING FROM CA COAST INTO SOUTHERN ROCKIES. NAM AND GFS INDICATE AN AREA OF WAA PRECIPITATION BREAKING OUT ACROSS IA AND MN WED EVENING AND LIFTING INTO WI. THE WAA PATTERN WEAKENS AS IT MOVES EAST AND FOCUS SHIFTS MORE TO DEVELOPING STORM IN SOUTHERN PLAINS. WILL KEEP FORECAST DRY FOR WEDNESDAY NIGHT AND INTO THURSDAY MORNING. STILL SOME DISCREPANCY BETWEEN GFS AND ECMWF/UKMET IN TIMING AND POSITIONING OF NEXT CYCLONE. GFS HAS A TENDENCY TO MOVE THESE SYSTEMS IN TOO FAST AND WILL TREND TOWARD SLOWER ECMWF. LATEST GFS BRINGS SURFACE LOW FROM NORTHERN MS THU EVENING TO NEAR BOWLING GREEN KY AND EVENTUALLY TO NEAR TOLEDO BY MIDDAY FRIDAY. BASED ON GFS SHOULD BE AN ALL SNOW EVENT...BUT IF ECMWF IS CORRECT AND LOW TAKES A MORE WESTERLY TRACK...PRECIP COULD MIX WITH OR CHANGE TO RAIN FAR SOUTHEAST COUNTIES. LOOKS LIKE THE BEST POTENTIAL FOR HEAVY SNOW SHOULD BE ALONG AND SE OF A STREATOR TO CHICAGO LINE. LESSER AMOUNTS UP TOWARD ROCKFORD. NEXT SHORT WAVE MOVING THROUGH IN NORTHERN STREAM ON SATURDAY. NOT MUCH MOISTURE OR DYNAMIC LIFT WITH THIS ONE AND BEST CHANCE OF LIGHT SNOW SHOULD STAY NORTH OF IL. THEN BROAD RIDGE REBUILDS AS NEXT POWERFUL STORM MOVES INTO THE WEST COAST THIS WEEKEND. COULD BRING RAIN OR SNOW TO THE AREA BY MONDAY. RLB/JJA && .AVIATION... 0600 UTC TAFS THE ACARS SOUNDING AT 0316 UTC SHOWS AN INVERSION WITH 54 KNOT WIND AT 3000 FT. THERE WILL BE GUSTS TO 30 KNOTS AT SURFACE OVERNIGHT. WILL KEEP AN EYE ON THE WIND OVERNIGHT. IF THE WIND DECREASES MORE THERE MAY BE LOW LEVEL WIND SHEAR. ADDED SOME FOG IN THE FORECAST BUT IT MAY NOT FORM BECAUSE OF THE WIND. THE FRONT WILL MOVE THROUGH AROUND 23 UTC IN CHICAGO AND 20 UTC IN ROCKFORD. THERE WILL BE SNOW BEHIND THE FRONT AND RAIN AND SNOW MIXED AHEAD OF THE FRONT. THE WIND WILL BE AT LEAST 20 TO 25 KNOTS FROM THE NORTHWEST LATE TUESDAY. SNOW AND BLOWING SNOW IS EXPECTED AFTER 20 UTC ACROSS ROCKFORD AND 23 UTC ACROSS CHICAGO AND GARY. WE USED THE LOCAL WRF AND THE NATIONAL WRF MODELS FOR GUIDANCE. && .MARINE... 258 AM CST DEEP LOW PRESSURE LIFTING NORTHEAST ACROSS ONTARIO THIS MORNING...WITH ARCTIC COLD FRONT TRAILING THROUGH THE PLAINS. THIS FRONT WILL PUSH EAST ACROSS LAKE MICHIGAN THIS AFTERNOON AS ANOTHER WAVE OF LOW PRESSURE RIPPLES NORTHEAST ALONG THE FRONT AND INTO THE GREAT LAKES BY TONIGHT. INTENSE SURFACE PRESSURE GRADIENT AND STRONG LOW LEVEL COLD ADVECTION EXPECTED TO RESULT IN 40-45 KNOT GALES DEVELOPING FROM WEST/NORTHWEST BEHIND FRONT LATER TODAY...WITH AIR TEMPERATURES FALLING INTO THE SINGLE DIGITS OVER THE LAKE TONIGHT. HEAVY FREEZING SPRAY WILL POSE STRONG ICING THREAT TONIGHT AND WEDNESDAY AS STRONG WINDS COMBINE WITH BITTER COLD...AND HAVE ISSUED HEAVY FREEZING SPRAY WARNING FROM 6 PM CST TONIGHT THROUGH THE DAY WEDNESDAY. GALES WILL GRADUALLY DIMINISH DURING THE DAY WEDNESDAY AS SECOND LOW ALSO MOVES NORTH TOWARD JAMES BAY...AND HIGH PRESSURE RIDGE BUILDS FROM PLAINS INTO GREAT LAKES AREA WEDNESDAY NIGHT. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING FROM NOON TODAY TO 12 PM CST WEDNESDAY FOR ILZ003>006-008-010>014-019>023-032-033-039. IN...WINTER STORM WARNING FROM NOON CST /1 PM EST/ TODAY TO 12 PM CST /1 PM EST/ WEDNESDAY FOR INZ001-002-010-011-019. LM...HEAVY FREEZING SPRAY WARNING FROM 6 PM THIS EVENING TO 6 PM CST WEDNESDAY FOR LMZ777-779. GALE WARNING UNTIL 12 PM CST WEDNESDAY FOR LMZ740>745-777-779. HEAVY FREEZING SPRAY WARNING FROM 6 PM THIS EVENING TO 12 PM CST WEDNESDAY FOR LMZ740>745. && $$ WFO LOT
AREA FORECAST DISCUSSION
NWS CHICAGO IL
1048 PM CST MON JAN 28 2008 .DISCUSSION... 310 PM CST FOCUS REMAINS ON DEEPENING TROF IN PLAINS OVERNIGHT WITH MINOR WAVES TRAVELING NE ON STRONG 60 KT LL JET AND FEEDING HEAT AND MSTR INTO THE MS VLY AND GREAT LAKES. LATEST WAVE OF RAIN SHUD BE DEPARTING TO THE EAST LATE THIS AFTN AND EVENING. NOT MUCH WAVE ACTIVITY SWINGING THRU AFTER THIS EVENING BUT AM KEEPING A MINIMAL CHANCE OF RAIN IN AREA OVERNIGHT WITH STRONG JET FEEDING MSTR INTO AREA. SFC FNT ASSOC WITH UPR TROF SWINGS ACRS MS RVR ARND DAYBREAK WHILE STILL DEEPENING...THEN INTO NE IL IN THE EARLY AFTN...THRU NW INDIANA BY SUNSET. WHILE RAIN CHANCES STILL VALID AHEAD OF COLD FRONT...MAIN ACTIVITY OF CONCERN WILL BE POST FRONTAL. HUGE PRESSURE RISES A FEW HOURS BEHIND FROPA SHUD ACCOMPANY A QUICK DROP IN DAYTIME TEMPERATURES USHERED IN BY STORM FORCE WINDS OF 45 TO 50 MPH. POST FRONTAL PCPN MAY START OFF AS A RAIN AND SNOW MIX BUT QUICKLY TURN OVER TO SNOW TUESDAY EVENING. MELTING SNOW SHUD TAKE LITTLE TIME TO FREEZE WITH THE BLAST OF COLD ARCTIC WIND...CAUSING ROADS TO BECOME SLICK VERY FAST. AN INCH OR TWO OR MAYBE 3 INCHES OF NEW SNOW ON TOP OF THIS WILL MAKE TRAVEL EVEN WORSE. THIS ADDITIONAL SNOW OF COURSE WILL BE BLOWN SIDEWAYS AND LOWERING VISIBILITY TO A QUARTER MILE OR LESS WILL BE MAKING ROAD CLEANUP IMPOSSIBLE. PRESENTLY AM LOOKING AT 2 TO 3 INCHES OF NEW SNOW NORTH OF I-88 WITH 1 TO 2 INCHES FROM I-88 SOUTH TO I-80 AND AN INCH OR LESS SOUTH OF I-80. LUCKILY THIS PCPN WILL BE OUT OF HERE QUICKLY OVERNIGHT TUES NGT BUT STILL BLOWING INTO THE MORNING HOURS WEDNESDAY. NIGHTTIME LOWS TUESDAY NIGHT WILL DROP INTO THE MINUS AND PLUS SINGLE DIGITS FROM I-80 NORTH...TO THE LOW DOUBLE DIGITS SOUTH.. WITH HIGH WINDS STILL BLOWING THRU THE NIGHT...WIND CHILLS WILL DROP INTO ADVISORY CATEGORY IN THE NORTH AT -20 TO -25F. HEADLINES WILL PROBABLY BE POSTED FOR ADVISORIES BY TMRW MRNG AND MAY EITHER BE MULTIPLE HEADLINES OR LIMITED TO A SINGLE HEADLINE TO INCORPORATE HIGH WINDS...BLINDING SNOW...AND WIND CHILLS. THIS WILL BE WINTER AT ITS WORST...THROWING EVERYTHING IT HAS AT US. WARMUP WILL BE RATHER QUICK INTO THE TEENS AND 20S FOR WEDNESDAY INTO THURSDAY AHEAD OF ANOTHER DEEPENING TROF. THIS ONE IS HEADED SOUTH OF THE AREA ACROSS THE SRN PLAINS. BROAD UPPER RIDGING OCCURS OVER THE MIDDLE OF THE CONUS THU IN RESPONSE TO NEXT TROF DROPPING FROM CA COAST INTO SOUTHERN ROCKIES. NAM AND GFS INDICATE AN AREA OF WAA PRECIPITATION BREAKING OUT ACROSS IA AND MN WED EVENING AND LIFTING INTO WI. THE WAA PATTERN WEAKENS AS IT MOVES EAST AND FOCUS SHIFTS MORE TO DEVELOPING STORM IN SOUTHERN PLAINS. WILL KEEP FORECAST DRY FOR WEDNESDAY NIGHT AND INTO THURSDAY MORNING. STILL SOME DISCREPANCY BETWEEN GFS AND ECMWF/UKMET IN TIMING AND POSITIONING OF NEXT CYCLONE. GFS HAS A TENDENCY TO MOVE THESE SYSTEMS IN TOO FAST AND WILL TREND TOWARD SLOWER ECMWF. LATEST GFS BRINGS SURFACE LOW FROM NORTHERN MS THU EVENING TO NEAR BOWLING GREEN KY AND EVENTUALLY TO NEAR TOLEDO BY MIDDAY FRIDAY. BASED ON GFS SHOULD BE AN ALL SNOW EVENT...BUT IF ECMWF IS CORRECT AND LOW TAKES A MORE WESTERLY TRACK...PRECIP COULD MIX WITH OR CHANGE TO RAIN FAR SOUTHEAST COUNTIES. LOOKS LIKE THE BEST POTENTIAL FOR HEAVY SNOW SHOULD BE ALONG AND SE OF A STREATOR TO CHICAGO LINE. LESSER AMOUNTS UP TOWARD ROCKFORD. NEXT SHORT WAVE MOVING THROUGH IN NORTHERN STREAM ON SATURDAY. NOT MUCH MOISTURE OR DYNAMIC LIFT WITH THIS ONE AND BEST CHANCE OF LIGHT SNOW SHOULD STAY NORTH OF IL. THEN BROAD RIDGE REBUILDS AS NEXT POWERFUL STORM MOVES INTO THE WEST COAST THIS WEEKEND. COULD BRING RAIN OR SNOW TO THE AREA BY MONDAY. RLB/JJA && .AVIATION... 0600 UTC TAFS THE ACARS SOUNDING AT 0316 UTC SHOWS AN INVERSION WITH 54 KNOT WIND AT 3000 FT. THERE WILL BE GUSTS TO 30 KNOTS AT SURFACE OVERNIGHT. WILL KEEP AN EYE ON THE WIND OVERNIGHT. IF THE WIND DECREASES MORE THERE MAY BE LOW LEVEL WIND SHEAR. ADDED SOME FOG IN THE FORECAST BUT IT MAY NOT FORM BECAUSE OF THE WIND. THE FRONT WILL MOVE THROUGH AROUND 23 UTC IN CHICAGO AND 20 UTC IN ROCKFORD. THERE WILL BE SNOW BEHIND THE FRONT AND RAIN AND SNOW MIXED AHEAD OF THE FRONT. THE WIND WILL BE AT LEAST 20 TO 25 KNOTS FROM THE NORTHWEST LATE TUESDAY. SNOW AND BLOWING SNOW IS EXPECTED AFTER 20 UTC ACROSS ROCKFORD AND 23 UTC ACROSS CHICAGO AND GARY. WE USED THE LOCAL WRF AND THE NATIONAL WRF MODELS FOR GUIDANCE. && .MARINE... 200 PM...DEEP BROAD LOW PRESSURE OVER THE DAKOTAS THIS AFTERNOON WILL MOVE NORTHEAST ACROSS ONTARIO LATE TONIGHT AND TUESDAY. A STRONG GRADIENT EXTENDS ACROSS THE WESTERN LAKES BETWEEN THIS LOW AND HIGH PRESSURE ACROSS THE MID ATLANTIC STATES...THUS GALES WILL CONTINUE THROUGH THE EVENING HRS AND BEGIN TO DIMINISH OVERNIGHT TOWARD DAWN TUESDAY. NEW LOW PRESSURE WILL DEVELOP OVER THE CENTRAL PLAINS TUESDAY MORNING...AND MOVE NORTHEAST ACROSS THE LAKES TUESDAY EVENING...AS IT RAPIDLY DEEPENS. COLD AIR WILL POUR IN BEHIND THIS SYSTEM TUESDAY NIGHT AS THE GRADIENT TIGHTENS. FOR NOW HAVE LEFT GALES TO 45 KNOTS DURING THIS PERIOD...BUT SOME WIND GUSTS TO STORM FORCE ARE CERTAINLY POSSIBLE. WINDS SLOWLY DIMINISH WEDNESDAY AS THE LOW LIFTS NORTHEAST ACROSS QUEBEC...WHILE STILL DEEPENING. A RIDGE OF HIGH PRESSURE MOVES ACROSS THE LAKES WEDNESDAY NIGHT INTO THURSDAY BEFORE ANOTHER SFC LOW MOVES NORTHEAST ACROSS THE OHIO VALLEY FRIDAY MORNING. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING FROM 12 PM TUESDAY TO 12 PM CST WEDNESDAY FOR ILZ003>006-008-010>014-019>023-032-033-039. IN...WINTER STORM WARNING FROM 12 PM CST /1 PM EST/ TUESDAY TO 12 PM CST /1 PM EST/ WEDNESDAY FOR INZ001-002-010-011-019. LM...GALE WARNING UNTIL 12 PM CST WEDNESDAY FOR LMZ740>745-777-779. && $$ WFO LOT
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1137 PM EST MON JAN 28 2008 .AVIATION...LOW LEVEL WIND SHEAR ANTICIPATED OVERNIGHT AT PLN/TVC/APN. AREA OF LIGHT TO MODERATE RAIN SHOWERS WILL MOVE THROUGH NORTHERN LOWER MICHIGAN...ENDING W-E BETWEEN 06Z AND 09Z CIGS WILL BOUNCE AROUND BETWEEN MVFR AND VFR THROUGH THE TIME...BUT EXPECTED TO LOWER TO PREDOMINATE MVFR LATER OVERNIGHT. ON TUESDAY... LIGHT RAIN AND DRIZZLE CONDITIONS EXPECTED TO PREVAIL WHILE IFR CIGS AND REDUCED VSBYS DEVELOP DUE TO ONGOING SNOW MELT. ADAM && .UPDATE...ISSUED AT 1045 PM. FIRST ROUND OF WARM ADVECTION DRIVEN PRECIP EXITING THE EASTERN THIRD OF THE CWA ATTM. AND DESPITE A VERY DRY ATMOSPHERE/ MIXED PRECIP CONCERNS TO START...ALL OBSERVATIONS REPORTING RAIN EVEN IN EASTERN UPPER MICHIGAN. A PERFECT EXAMPLE OF THE MAGNITUDE OF WARM ADVECTION OVERWHELMING THE DEGREE OF EVAPORATIVE AND DYNAMIC COOLING. SFC DEWPOINTS AT MOST OBS SITES NOW AROUND OR ABOVE 32F. SO LOOKS LIKE ANY FREEZING RAIN THREAT HAS BEEN AVERTED. MEANWHILE UPSTREAM...SATELLITE IMAGERY SHOWING STRONG MID LEVEL SHORT WAVE PUNCHING INTO SW WISCONSIN WITH PRONOUNCED MID LEVEL DRYING BEHIND. SECOND AREA OF ASSOCIATED COOLING CLOUD TOPS AND EXPANDING PRECIP PUSHING OUT OF EASTERN WISCONSIN AND ACROSS THE LAKE. FOR THE REST OF TONIGHT...MAIN FORECAST ISSUES REVOLVE AROUND CONTINUING PRECIP CHANCES/P-TYPE...AND FOG POSSIBILITIES. SATELLITE/ RADAR EXTRAPOLATION SUGGESTS UPSTREAM SHORT WAVE AND SECOND ROUND OF LIGHT PRECIP WILL TRAVERSE SW-NE THROUGH THE CWA BETWEEN NOW AND ROUGHLY 09Z...PERHAPS HANGING ON THROUGH 12Z IN EASTERN UPPER. UPSTREAM DRY SLOT FOLLOWS SUITE AND 00Z NAM FORECAST SOUNDINGS THEN SUGGEST SOME DRIZZLE POSSIBILITIES AS SATURATED LOWER LAYERS DROP WELL BELOW THE -10C LEVEL. WILL CRAFT UPDATED GRIDS/ZONE FORECASTS ACCORDINGLY. AS FAR AS P-TYPE IS CONCERNED...MOST OBS SITES ACROSS NRN LOWER MICHIGAN REPORTING DEWPOINTS >32F...AND 00Z NAM FORECAST SOUNDINGS STILL SUGGEST ALL LIQUID. ONLY EXCEPTION REMAINS IN EASTERN UPPER MICHIGAN WHERE MUCH OF THE SOUNDING TEMP PROFILE COOLS BELOW FREEZING OVERNIGHT AND SUGGESTS A RAIN/SNOW MIX POTENTIAL. FOG ISSUES...DESPITE THE RAIN AND MELTING SNOWPACK...STRONG WINDS AND POCKETS OF LINGERING LOW LEVEL DRIER AIR (AS EVIDENCED BY CLR SKY REPORTS IN SFC OBS) HAVE KEPT FOG IN CHECK. AND BELIEVE THIS WILL REMAIN THE CASE THROUGH THE NIGHT. FOG POTENTIAL ACTUALLY LOOKS BETTER ON MONDAY AS WINDS DIMINISH/HIGHER DEWPOINT AIR CONTINUES TO ADVECT INTO THE REGION AND MELTING PROCEEDS. WITH THIS IN MIND HAVE ADDED AREAS OF FOG TO THE GOING TUESDAY FORECAST. ADAM && .DISCUSSION...ISSUED AT 345 PM. SHORT TERM (TONIGHT)...986MB SURFACE LOW OVER ND LATE THIS AFTERNOON WILL CONTINUE TO STRENGTHEN AS IT SLIDES TO A POSITION OFF THE NORTH SHORE OF LAKE SUPERIOR TUESDAY MORNING. WARM ADVECTION WITHIN BROAD SOUTHWEST LOW/MID LEVEL FLOW SPREADING CLOUDS AND SOME LIGHT PRECIPITATION ACROSS IL/IN/WI...THOUGH STILL NOT MUCH REACHING THE GROUND ACROSS WI AS PRECIPITATION STRUGGLES THROUGH DRY AIR MASS IN PLACE OVER THE WESTERN LAKES. A SECOND AREA OF PRECIPITATION STRETCHED FROM NE/EASTERN SD/WESTERN MN AHEAD OF A SHORT WAVE TROUGH COMING OUT OF CO AND FOCUSED ALONG AN AXIS OF MID LEVEL FRONTOGENESIS. ALTHOUGH F-GEN FORCING DOES NOT LOOK LIKE IT WILL IMPACT NORTHERN MI TONIGHT...COMBINATION OF PERSISTENT WARM ADVECTION AND AN ADDED BOOST FROM AFOREMENTIONED SHORT WAVE WHICH IS EXPECTED TO CROSS THE FORECAST AREA OVERNIGHT SHOULD RESULT IN AN INCREASE IN PRECIPITATION COVERAGE DURING THE LATE AFTERNOON AND THROUGH THE EVENING HOURS. NEXT ISSUE IS PRECIPITATION TYPE... TEMPERATURES HAVE WARMED QUITE NICELY ACROSS THE REGION THIS AFTERNOON...MID/UPPER 30S ACROSS EASTERN UPPER/NORTHEAST AND NORTH CENTRAL LOWER...WITH MID/UPPER 40S ALONG THE LAKE MICHIGAN SHORELINE AIDED BY DOWNSLOPE WIND COMPONENT. MODEL VERTICAL TEMPERATURE PROFILES ARE QUITE DIFFERENT TONIGHT...WITH THE GFS BEING COLDER THAN THE NAM. EARLY AFTERNOON AIRCRAFT SOUNDINGS OUT OF PLN/CIU ARE SIMILAR TO GUIDANCE 6H FORECASTS...BUT SUGGEST THAT SOMETHING IN BETWEEN IS PROBABLY MORE REFLECTIVE OF REALITY. THE MAIN CONCERN WILL BE ACROSS EASTERN UPPER WHERE COLUMN ALOFT SHOULD BE COLD ENOUGH FOR ALL SNOW...SO PRECIP TYPE WILL BE FOCUSED ON DEPTH OF SURFACE BASED WARM LAYER. BOTH NAM/GFS SUGGESTING THAT SURFACE BASED WARM LAYER WILL BE MINIMAL/NON-EXISTENT AND THAT PRECIP WILL BE ALL SNOW. PROBLEM IS THAT SURFACE TEMPERATURES IN BOTH MODELS ARE RUNNING WELL SHORT OF CURRENT OBSERVATIONS (A GOOD 4-8 DEGREES)...WITH MID/UPPER 40S TEMPERATURES FLOODING UP THROUGH THE STRAITS AND INTO AT LEAST MACKINAC COUNTY (ERY UP TO 43F AT 20Z...MCD AT 45F). LOSS OF DIURNAL HEATING AND WET BULB COOLING WILL HAVE SOME IMPACT...BUT CURRENT THINKING IS THAT BEST CHANCE FOR SNOW OR MIXED RAIN/SNOW WILL BE ACROSS NORTHERN AND PERHAPS FAR EASTERN PORTIONS OF CHIPPEWA COUNTY. GIVEN SURGE IN SURFACE TEMPERATURES THIS AFTERNOON APPEARS FREEZING RAIN THREAT ACROSS NORTHEAST LOWER WILL BE MINIMAL...ONLY REAL CONCERN IS HIGHER TERRAIN ACROSS INTERIOR NORTHERN LOWER. EXPECT PRECIPITATION TO TAPER OFF TO DRIZZLE LATE AS MID LEVEL MOISTURE GETS STRIPPED OUT IN WAKE OF SHORT WAVE TROUGH. ONSET OF PRECIPITATION MAY ALSO BRING A PERIOD OF STRONG WINDS DUE TO THE DRY LOW LEVELS. GUSTS IN EXCESS OF 40 MPH WILL BE POSSIBLE THIS EVENING. JPB REMAINDER OF THE FORECAST (TUESDAY THROUGH NEXT MONDAY)...A VERY BUSY STRETCH OF WEATHER IS EXPECTED OVER THE NEXT SEVERAL DAYS. THE MAIN FORECAST CONCERNS WILL REVOLVE AROUND THE DETAILS OF A VIGOROUS WEATHER SYSTEM MOVING ACROSS THE AREA TUESDAY NIGHT AND WEDNESDAY INCLUDING WHETHER OR NOT HEADLINES WILL BE NECESSARY. THEREAFTER...POPS WILL BE THE MAIN ISSUE AS THE PATTERN REMAINS RATHER ACTIVE. TUESDAY...RELATIVE LULL IN THE ACTION AS THE FIRST AREA OF LOW PRESSURE CONTINUES TO TRACK ACROSS ONTARIO. DO NOT BE FOOLED THOUGH AS AN ARCTIC COLD FRONT WILL BE LURKING ACROSS THE MID MISSISSIPPI VALLEY. MODEL SOUNDINGS/CROSS SECTIONS SHOW MOISTURE SHALLOWING OUT...MAINLY CONFINED TO BELOW 800 MB. THEREFORE...WILL CONTINUE WITH ONLY A CHANCE OF LIGHT RAIN AND DRIZZLE FOR MUCH OF THE DAY. HIGHS OF WELL INTO THE 30S TO AROUND 40 EXPECTED WITH SOUTH SOUTHWEST WINDS OF BETWEEN 10 AND 20 MPH. LATE TUESDAY INTO TUESDAY NIGHT...STRONG FORCING ALONG WITH ABUNDANT MOISTURE OUT AHEAD OF THE VIGOROUS COLD FRONT WILL QUICKLY OVERSPREAD THE REGION FROM THE WEST LEADING TO RAINFALL ACROSS THE ENTIRE FORECAST AREA LATE IN THE AFTERNOON. THE ARCTIC COLD FRONT THEN PLOWS ACROSS THE REGION IN THE EVENING WITH VERY STRONG COLD AIR ADVECTION BEHIND IT (850 MB TEMPERATURES PLUMMET FROM AROUND PLUS 4 C AT 00Z TUE TO BETWEEN -20 AND -25 C AT 12Z) LEADING TO FALLING TEMPERATURES LIKELY LEADING TO A RAPID FREEZE UP OF AREA ROADWAYS. MEANWHILE...A WAVE OF LOW PRESSURE MOVES UP ALONG THE FRONT WHILE RAPIDLY INTENSIFYING TO BETWEEN 975 AND 980 MB. 925 MB WINDS OF 35 TO 40 KNOTS ARE NOT EXPECTED TO HAVE TOO MUCH OF A PROBLEM MIXING DOWN WHICH WOULD LEAD TO THE POTENTIAL FOR BLIZZARD LIKE CONDITIONS DEVELOPING AT TIMES TUESDAY EVENING AND TUESDAY NIGHT (AND GALES ACROSS NEARSHORE ZONES). THEREFORE...WILL ISSUE A WINTER STORM WATCH FROM TUE EVENING THROUGH WED ACROSS ALL ZONES EXCEPT GLADWIN AND ARENAC COUNTIES FOR THE COMBINATION OF STRONG WINDS...LOW VISIBILITIES AND LOW WIND CHILLS. ACCUMULATIONS WED NIGHT ARE EXPECTED TO RANGE FROM AN INCH OR TWO SOUTHEAST TO FOUR OR FIVE INCHES ACROSS EASTERN UPPER WHERE THE BEST WRAP AROUND MOISTURE IS SHOWN. TEMPERATURES WILL PLUNGE OVERNIGHT ENDING UP BETWEEN 10 AND 15 DEGREES BY WED MORNING. WEDNESDAY...850 MB TEMPERATURES BOTTOM OUT BETWEEN -23 AND -28 C. THE MEAN SURFACE-850 MB FLOW SETTLES IN OUT OF THE WEST LEADING TO LAKE EFFECT SNOW SHOWERS. MEAN 900-700 MB RH FALLS FROM BETWEEN 70 AND 80 PERCENT IN THE MORNING TO BETWEEN 30 AND 50 PERCENT IN THE AFTERNOON. MEAN 1000-850 MB WINDS REMAIN ABOUT 30 KNOTS THROUGH THE DAY SO LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO BE PUSHED ALL THE WAY TO THE LAKE HURON SHORELINE. ACCUMULATIONS DO NOT LOOK OVERLY IMPRESSIVE AS COLD THERMAL REGIME WOULD SUPPORT SMALL SNOWFLAKE PRODUCTION SO A COUPLE OF INCHES EXPECTED IN WESTERLY FLOW FAVORED AREAS AND AN INCH OR LESS ELSEWHERE. HOWEVER...EXTENSIVE BLOWING AND DRIFTING SNOW IS EXPECTED TO CONTINUE LEADING TO POTENTIAL FOR HAZARDOUS TRAVEL CONDITIONS. TEMPERATURES WILL REMAIN NEARLY STEADY IN THE TEENS OR FALL INTO THE UPPER SINGLE DIGITS AS COLD AIR ADVECTION CONTINUES. WIND CHILLS VALUES COULD BE AS LOW AS 10 TO 15 DEGREES BELOW ZERO. WEDNESDAY NIGHT INTO THURSDAY...LAKE EFFECT IS EXPECTED TO LINGER AS 850 MB TEMPERATURES BEGIN TO STEADILY RISE BACK INTO THE -10 TO -15 C RANGE. THE FLOW IS SHOWN TO BACK FROM THE WEST INTO THE SOUTHWEST BY THURSDAY. LOWS WED NIGHT WITHIN A FEW DEGREES EITHER SIDE OF ZERO. HIGHS ON THURSDAY RANGING FROM THE UPPER TEENS TO THE MIDDLE 20S. FRIDAY THROUGH NEXT MONDAY...ACTIVE WEATHER PATTERN CONTINUES WITH AN ENERGETIC SOUTHERN JET STREAM SENDING ENERGY NORTHWARD TOWARD THE GREAT LAKES. THERE IS THE POTENTIAL FOR MAJOR STORM SYSTEM TO AFFECT THE REGION ON FRIDAY AND AGAIN SOMETIME EARLY NEXT WEEK. IN BETWEEN...AN ALBERTA CLIPPER WILL BRING A CHANCE OF LIGHT SNOW LATE SATURDAY INTO SATURDAY NIGHT. NO ARCTIC AIR IS IN SIGHT WITH SEASONABLE TEMPERATURES EXPECTED WITH HIGHS IN THE UPPER 20S TO LOWER 30S AND LOWS IN THE TEENS. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR MIZ008-015>036. LM...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LMZ323-341-342-344>346. LH...GALE WARNING UNTIL 10 AM EST TUESDAY FOR LHZ345>349. && $$
AREA FORECAST DISCUSSION
NWS SEATTLE WA
350 AM PST TUE JAN 29 2008 .SYNOPSIS...A FRONT WILL MOVE THROUGH WESTERN WASHINGTON. INCREASING ONSHORE FLOW BEHIND THE FRONT WILL LIFT THE SNOW LEVEL UP TO NEAR 1000 FEET BRIEFLY THIS AFTERNOON. A COOL UPPER LEVEL TROUGH BEHIND THE FRONT WILL MOVE INTO THE AREA LATE THIS AFTERNOON AND TONIGHT KEEP SHOWERS IN THE FORECAST WITH THE SNOW LEVEL BELOW 1000 FEET. ANOTHER FRONTAL SYSTEM WILL BRING MORE RAIN AND MOUNTAIN SNOW TO THE AREA ON LATE WEDNESDAY. EXPECT A COOL AND MOIST WEATHER PATTERN TO CONTINUE THROUGH EARLY NEXT WEEK. && .SHORT TERM...SATELLITE IMAGERY SHOWS COLD FRONT JUST OFF THE COAST AT 11Z. IF YOU WANT THE DEFINITION OF A BORDERLINE SNOW SITUATION WE HAVE HAD IT OVERNIGHT. ACARS SOUNDINGS AFTER MIDNIGHT PUT THE FREEZING LEVEL JUST ABOVE 1000 FEET WITH THE AMS ISOTHERMAL UP TO 2000 FEET. SOUTHERLY SURFACE GRADIENTS HAVE ONLY KEPT TEMPERATURES IN THE MID 30S. HEAVIER PRECIPITATION NEAR THE FRONT HAS RESULTED IN SNOW AT KUIL THE LAST COUPLE OF HOURS. IN BELLINGHAM...THE WINDS SWITCHED TO SOUTHEAST IN THE LAST HOUR AND THE TEMPERATURE ROSE TO 27 DEGREES WITH THE SNOW TEMPORARILY STOPPING. GAME PLAN FOR THIS MORNING...FRONT MOVES THROUGH COAST 12Z-14Z...INTERIOR 14Z-18Z. ITS STILL POSSIBLE TO GET A BRIEF SHOT OF SNOW OVER THE INTERIOR OUTSIDE OF WHATCOM COUNTY JUST AHEAD OF THE FRONT AS THE PRECIPITATION INTENSITY INCREASES. FOR WHATCOM COUNTY SNOW POSSIBLE UP UNTIL THE FRONT PASSES BUT WITH THE REMAINING QPF VALUES EXPECTED AROUND A TENTH JUST ANOTHER INCH OF SNOW POSSIBLE WILL EXTEND THE SNOW ADVISORY UNTIL 10 AM. INCREASING ONSHORE GRADIENTS BEHIND THE FRONT WILL BUMP UP THE SNOW LEVEL A FEW HUNDRED FEET MIDDAY TODAY. ONCE AGAIN LATE THIS AFTERNOON THE SNOW LEVEL WILL DROP DOWN TO THE EVER POPULAR NEAR 500 FEET AS A COLD UPPER LEVEL TROUGH BEHIND THE FRONT...1000-850 MB THICKNESS VALUES AROUND 1290M...MOVES INTO THE AREA. THE FLOW ALOFT WILL SHADOW THE CENTRAL SOUND A LITTLE TONIGHT WITH A CONVERGENCE ZONE POSSIBLE TO THE NORTH BUT WITH THE FLOW ALOFT EXPECT THE CONVERGENCE TO GET PUSHED MOSTLY INTO THE CASCADES. TROUGH SHIFTS EAST EARLY WEDNESDAY WITH THE NEXT FRONTAL SYSTEM REACHING WESTERN WASHINGTON WEDNESDAY NIGHT. THE AMS LOOKS WARM ENOUGH WITH THIS SYSTEM THAT THE PRECIPITATION IN THE LOWLANDS WILL BE IN THE FORM OF RAIN. ANOTHER COLD...BUT NOT AS COLD AS THE TROUGH TODAY...FALLS IN BEHIND THE FRONT FOR THURSDAY. THE LA NINA WINTER CONTINUES. .LONG TERM...NOT MUCH CHANGE IN THE PATTERN WITH A COOL UPPER LEVEL TROUGH HANGING OUT ALONG THE PACIFIC NORTHWEST COAST. A MORE ORGANIZED FEATURE CURRENTLY TIMED INTO WESTERN WASHINGTON LATE DAY SIX INTO DAY SEVEN. WILL GO FOR LIKELY POPS THEN. IN THE MEANTIME COOL WITH A CHANCE OF SHOWERS WILL BE THE RULE. NO CHANGES TO THE EXTENDED FORECAST THIS MORNING. FELTON && .AVIATION...MVFR CEILINGS TO CONTINUE THROUGH THIS MORNING...WITH FRONTAL PASSAGE THROUGH THE PUGET SOUND AREA EXPECTED AROUND 14Z OR 15Z. THERE ARE STILL A FEW POCKETS OF MIXED RAIN AND SNOW SHOWING UP IN A FEW OBS...BUT THE ARRIVAL OF THE FRONT SHOULD EFFECTIVELY MIX THINGS UP AND TURN IT ALL TO RAIN. SNOW AT BELLINGHAM MAY CONTINUE THROUGH 18Z OR LATER...WHEN COLD AIR FINALLY GETS SCOURED OUT. KSEW PROFILER IS SHOWING SW WIND AT 35 KNOTS NEAR 5000 FT AND THEY COULD REACH UP TO 50 KNOTS NEAR AND JUST AHEAD OF FRONTAL PASSAGE BETWEEN 12Z AND 15Z. FOR KSEA...MVFR CEILINGS TO CONTINUE INTO THE AFTERNOON. AS PREVIOUSLY MENTIONED...SOUTHERLY WINDS AT 5000 FT WILL APPROACH 50 KNOTS BETWEEN 12Z AND 15Z NEAR AND WITH FRONTAL PASSAGE. SURFACE WINDS WILL BECOME GUSTY OUT OF THE SOUTHWEST BEHIND THE FRONT LATER THIS MORNING...POSSIBLY UP TO 25 KNOTS OR SO AT TIMES. 27 && .MARINE...EXISTING ADVISORIES AND WARNINGS REMAIN IN EFFECT. POST FRONTAL WINDS OVER PUGET SOUND COULD APPROACH GALE FORCE LATER THIS MORNING....BUT HAVE CHOSEN TO STICK WITH HIGH END SMALL CRAFT ADVISORY FOR NOW. 27 && .AVALANCHE...AVALANCHE WARNING FOR WASHINGTON CASCADES, OLYMPICS AND MT HOOD AREA FOR EARLY TUESDAY MORNING THROUGH TUESDAY NIGHT. NUMEROUS WEAK LAYERS IN PLACE AS WELL AS FIRM UNDERLYING CRUSTS TO PROVIDE SLIDING SURFACES. INCOMING STRONG WINDS AND HEAVY LOADING WILL TIP THE BALANCE AND MAKE FOR WIDESPREAD AVALANCHES TUESDAY. SEE NWAC.US FOR FORECAST DETAILS. KK && .SEW WATCHES/WARNINGS/ADVISORIES... .GALE WARNING COASTAL WATERS AND STRAIT OF JUAN DE FUCA. .SMALL CRAFT ADVISORY ALL INLAND WATERS. .SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR. .HEAVY SNOW WARNING UNTIL 4 AM PST WEDNESDAY FOR THE OLYMPICS AND CASCADES. .SNOW ADVISORY UNTIL 10 AM PST TUESDAY FOR WESTERN WHATCOM COUNTY. $$ WEATHER.GOV
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
502 AM CST TUE JAN 29 2008 .SHORT TERM...TODAY THROUGH WEDNESDAY. 180KT JET LIFTING OUT OF SOUTHWEST UNITED STATES CAN BE SEEN FROM AIRCRAFT DATA EARLY THIS MORNING. THIS STRONG JET WILL LIFT NORTHEAST TODAY AND TONIGHT AND HELP DEEPEN SURFACE LOW THAT WAS NEAR KANSAS CITY AT 09Z. THIS LOW IS FORECAST TO MOVE TO NORTH OF SAULT SAINTE MARIE BY MIDNIGHT. FAST MOVEMENT WILL KEEP SNOWFALL TOTALS FAIRLY MODEST. WHILE THE SNOWFALL AMOUNTS MAY NOT BE THAT GREAT...STRONG WINDS WILL CREATE NEAR BLIZZARD CONDITIONS DURING THE LATE AFTERNOON AND EVENING... ESPECIALLY IN THE EASTERN ZONES WHERE THE GRADIENT IS STRONGEST. LATER SHIFTS WILL LIKELY REPLACE THE CURRENT WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES WITH WIND CHILL WARNINGS OR ADVISORIES ONCE THE SNOW DIMINISHES THIS EVENING. .LONG TERM...WEDNESDAY NIGHT THROUGH NEXT MONDAY UNLIKE THE SYSTEM PUSHING THROUGH THE AREA THIS AFTERNOON... MINOR FEATURES AND MOISTURE WILL BE THE SIGNIFICANT FEATURES TO PRECIPITATION CHANCES IN THE WEDNESDAY NIGHT THROUGH THURSDAY NIGHT TIME FRAME. HIGH PRESSURE IS EXPECTED TO SLIDE EAST OF THE AREA WEDNESDAY EVENING. WEAK WARM ADVECTION NOTED AT 850MB BEGINS AFTER 06Z...COMBINED WITH A JET STREAK MOVING ACROSS THE AREA LATER WEDNESDAY NIGHT INTO THURSDAY MORNING WILL TRIGGER AN EAST WEST BAND OF LIGHT SNOW. THIS IS SUPPORTED BY THE GFS/WRF DEPICTION OF VERY DRY AIR AT 850MB AND 925MB ACROSS MUCH OF THE AREA...BUT A NARROW RIBBON OF MOISTURE IS EXPECTED TO DEVELOP OVER THE FAR SOUTHERN PORTION OF THE FORECAST AREA LATER WEDNESDAY NIGHT. CONTINUED THE CHANCES FOR FLURRIES OR LIGHT SNOW OVER THE FAR SOUTH. SEVERAL WEAK DISTURBANCE EXPECTED TO MOVE ACROSS THE AREA BETWEEN WEDNESDAY NIGHT AND THURSDAY NIGHT WILL MAKE IT HARD TO PINPOINT WHEN IT WOULD SNOW...BUT BEST CHANCES APPEAR TO BE LATE WEDNESDAY NIGHT INTO THURSDAY MORNING AND AGAIN THURSDAY NIGHT. CONTINUED 30-40 PERCENT CHANCES FOR SNOW OVER THE SOUTH...AND BROUGHT A SMALL CHANCE OF LIGHT SNOW OR FLURRIES FURTHER NORTH DURING THE DAY THURSDAY AND THURSDAY NIGHT. CONTINUED WITH LIGHT SNOWFALL AMOUNTS UNDER AN INCH...BUT CONCERNED THAT THERE COULD BE A NARROW BAND OF HEAVIER SNOW IF IT SNOWS OVER THE SAME AREA FOR A LONGER PERIOD OF TIME. LATER SHIFTS CAN FINE TUNE THE DETAILS ONCE WE GET CLOSER TO THE EVENT. ALL THE MODELS SUGGEST THAT THE STRONGER SYSTEM FOR FRIDAY WILL PASS SOUTH OF THE FORECAST AREA. ANALYSIS OF THE MODEL DATA WOULD SUGGEST THAT THE TRACK MAY BE A LITTLE FURTHER NORTH THAN WHAT THE 00Z MODELS INDICATE. ALSO...THE TREND THIS WINTER IS FOR WINTER STORMS ENDING UP FURTHER NORTH AND WEST OF THE MODEL TRACK 48 TO 72 HOURS IN ADVANCE OF THE SYSTEM. WILL CONTINUE WITH PERSISTENCE FOR NOW AND SEE IF THIS DOES WORK OUT. AN UPPER LEVEL DISTURBANCE MOVES ACROSS THE AREA...BRINGING A SMALL CHANCE FOR LIGHT SNOW ON SATURDAY. NEXT SYSTEM FOR EARLY NEXT WEEK IS MUCH WEAKER THAN YESTERDAY. THE MODELS HAVE DIVERGED WITH THE SURFACE LOW PATH WITH GFS MOVING IT NORTH OF WISCONSIN WHILE THE ECMWF TAKES THE SYSTEM SOUTH OF THE STATE. LITTLE CHANGES MADE BEYOND SATURDAY NIGHT. && .AVIATION...MVFR/IFR CIGS EXPECTED THROUGH MIDDAY IN MOST PLACES...WITH IFR CIGS AND VSBYS IN SNOW BY LATE AFTERNOON AND CONTINUING THIS EVENING. SNOW AND BLOWING SNOW COULD PRODUCE VSBYS BELOW AIRPORT MINIMA LATER TODAY. && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 8 AM CST WEDNESDAY FOR WIZ022-038>040-048>050-073-074. WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO 8 AM CST WEDNESDAY FOR WIZ005-010>013-018>021-030-031-035>037-045. && $$ RDM/ECKBERG