Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/23/13


AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
930 AM PST THU FEB 21 2013 .SYNOPSIS... NORTHERLY FLOW ALOFT WILL CONTINUE ACROSS THE REGION THROUGH SATURDAY AND RESULT IN ONLY A SLIGHT WARMING TREND. A WEAK DISTURBANCE WILL PRODUCE SCATTERED LIGHT SHOWERS TODAY INTO THIS EVENING...WITH SHOWERS MOST COMMON IN THE MOUNTAINS. PATCHY FROST IS EXPECTED IN THE VALLEYS TONIGHT. GUSTY WESTERLY WINDS ARE EXPECTED IN THE MOUNTAINS AND DESERTS SATURDAY...THEN STRONGER NORTHEAST WINDS WILL DEVELOP THROUGH AND BELOW PASSES AND CANYONS LATE SATURDAY NIGHT AND SUNDAY AS ANOTHER UPPER-LEVEL TROUGH OF LOW PRESSURE SLIDES SOUTHEAST THROUGH THE GREAT BASIN. MOSTLY SEASONAL TEMPERATURES ARE EXPECTED EARLY NEXT WEEK UNDER NORTHWEST FLOW. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A FEW SHOWERS WERE OCCURRING THIS MORNING AHEAD OF A SHORTWAVE MOVING SOUTHEAST THROUGH CENTRAL CALIFORNIA. SOME DENSE FOG WAS OCCURRING OVER THE MOUNTAINS WHERE THE CLOUDS WERE INTERSECTING THE TERRAIN...MOSTLY ABOVE 4000 FEET ABOVE SEA LEVEL. EXPECT SOME MORE SHOWERS TODAY AS HIGH-RES MODELS SUCH AS THE HRRR AND LOCAL WRF ARE SHOWING SCATTERED LIGHT PRECIP AND MODERATELY HIGH RH MOSTLY BELOW 700 MB. SNOW LEVELS WILL BE RISING TO ABOUT 5000 FEET DURING THE AFTERNOON. PRECIP SHOULD END NORTH TO SOUTH LATE TODAY/EARLY THIS EVENING...AND MOST AREAS SHOULD CLEAR BY LATE TONIGHT. WHILE LOCALLY GUSTY WINDS ARE PROGGED THROUGH/BELOW N-S/NE-SW ORIENTED PASSES/CANYONS SUCH AS CAJON PASS AND IN THE SANTA ANA MTNS TONIGHT/EARLY FRI...GUST POTENTIAL IS AROUND 40 MPH AT 12Z/4 AM...AND MOSTLY AT HIGHER ELEVATIONS...SO NO WIND ADVISORY WILL BE ISSUED. A FROST ADVISORY MIGHT BE NEEDED IN THE VALLEYS TONIGHT AS MOST VALLEY FLOORS WILL HAVE LITTLE/NO WIND AND CLEAR SKIES UNDER THE COLD AIR MASS WITH 850 MB TEMPS STILL AROUND 3-4 DEG C. WILL EVALUATE FOR THE AFTERNOON PACKAGE. N/NW FLOW ALOFT WILL CONTINUE THROUGH SATURDAY AND RESULT IN ONLY A SLOW WARMING TREND...WITH TEMPS REMAINING BELOW NORMAL. A GULF OF ALASKA TROUGH WILL MOVE THROUGH THE PAC NW FRI NIGHT AND THROUGH UTAH SAT NIGHT. TEMP GRADIENTS WILL INCREASE IN THE 850-700 MB LAYER...AND 12Z NAM SHOWS 40-KNOT WINDS AT 850 MB...DOWN A BIT FROM THE PREVIOUS RUN...AND ABOUT A 16-MB SURFACE PRESSURE GRADIENT FROM NE NEVADA TO SAN DIEGO. HENCE...LOOKS LIKE SOME DECENT NE WINDS THROUGH/BELOW PASSES AND CANYONS...WITH POSSIBLE GUSTS OVER 55 MPH...MAINLY INLAND EMPIRE/SANTA ANA MTNS/SAN DIEGO COUNTY MTNS. THE OFFSHORE FLOW SHOULD FINALLY BRING SOME WARMING W OF THE MTNS. THE NEXT INSIDE-SLIDER TROUGH FOR TUESDAY LOOKS MUCH WEAKER AND FURTHER NE THAN MODEL SOLUTIONS FROM YESTERDAY...INCLUDING IN MOST OF THE ENSEMBLE RUNS. HENCE...GENERALLY FAIR WEATHER WITH SEASONAL TEMPS THEN. && .AVIATION... 211600Z...A WEAK COASTAL EDDY WILL CONTINUE SCT-BKN LOW CLOUDS ALONG THE COAST AND IN THE INLAND VALLEYS THROUGH THIS MORNING...WITH BASES BETWEEN 2500 AND 3500 FT MSL AND TOPS TO 5000 TO FT MSL. A WEAK WEATHER DISTURBANCE MOVING OVER THE AREA THIS AFTERNOON WILL BRING ISOLATED LIGHT SHOWERS OVER AND WEST OF THE MOUNTAINS...MOSTLY CONFINED TO SAN DIEGO COUNTY. HOWEVER...HAVE OPTED TO KEEP KSAN TAF FEW/SCT040 WITH CONFIDENCE TOO LOW TO INCLUDE ANY PRECIPITATION. CLOUD COVER WILL BE DECREASING OVERNIGHT OVER ALL AREAS. && .MARINE... THE SMALL CRAFT ADVISORY FOR THE OUTER COASTAL WATERS HAS BEEN ALLOWED TO EXPIRE. HOWEVER...COMBINED SEAS OF 7 TO 9 FEET ARE EXPECTED THROUGH LATE THIS MORNING...AS WINDS CONTINUE TO DIMINISH. && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...MAXWELL AVIATION/MARINE...JT
AREA FORECAST DISCUSSION...UPDATE
NWS SAN DIEGO CA
525 AM PST THU FEB 21 2013 .SYNOPSIS... A COOL NORTHERLY FLOW WILL CONTINUE ACROSS THE REGION INTO THE WEEKEND. A WEAK DISTURBANCE MAY PRODUCE A FEW LIGHT SHOWERS TODAY AND TONIGHT...OTHERWISE IT WILL BE PARTLY CLOUDY AND SLIGHTLY WARMER. QUITE COOL AGAIN TONIGHT WITH PATCHY FROST POSSIBLE AGAIN IN THE VALLEYS. GUSTY ONSHORE WIND SATURDAY WILL TURN OFFSHORE AND BECOME GUSTY THROUGH AND BELOW PASSES AND CANYONS LATE SATURDAY NIGHT AND SUNDAY AS ANOTHER UPPER-LEVEL TROUGH SLIDES SOUTHEAST THROUGH THE GREAT BASIN. SEASONAL TEMPS AND DRY NEXT WEEK UNDER NORTHWEST FLOW ALOFT. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A FEW LOW CLOUDS WERE DEVELOPING EARLY THIS MORNING OVER COASTAL AREAS...OTHERWISE SKIES WERE MOSTLY CLEAR. WINDS WERE MOSTLY LIGHT...EXCEPT IN SOME MOUNTAIN AND DESERT AREAS WHERE THEY WERE LOCALLY 15 TO 25 MPH. AN UPPER-LEVEL HIGH WAS CENTERED OVER THE PACIFIC NEAR 160W...WHILE A BROAD TROUGH COVERED THE WESTERN U.S. A SHORT-WAVE TROUGH WILL DIVE SOUTH ACROSS CA TODAY...INCREASING CLOUDS AND BRINGING A CHANCE FOR MORE LIGHT SNOW AND RAIN SHOWERS. BEST CHANCE FOR ACCUMULATIONS WILL BE IN THE MOUNTAINS. THE WAVE IS WELL DEVELOPED ON WATER VAPOR IMAGERY EARLY THIS MORNING NEAR THE NORTHERN CA BORDER. THIS DISTURBANCE WILL EXIT THE REGION THIS EVENING...ALLOWING SKIES TO CLEAR...SETTING US UP FOR ANOTHER CHILLY NIGHT. ANOTHER...STRONGER WAVE WILL DIG SOUTH OVER THE WEEKEND. THIS ONE IS WELL DEVELOPED ON SATELLITE IMAGERY NEAR THE BRITISH COLOMBIA COAST. GLOBAL MODELS ALL DIG THE WAVE...BUT IT IS MOST AMPLIFIED ON THE 00Z ECMWF/GEM MODELS. DEPENDING ON HOW STRONGLY IT DIGS...ONSHORE FLOW MAY BECOME STRONG AND GUSTY OVER THE MTNS/DESERTS AGAIN ON SAT... BEFORE TURNING BACK OFFSHORE AND BECOMING GUSTY THROUGH WND BELOW THE OFFSHORE WIND PRONE PASSES AND CANYONS LATE SAT NIGHT AND SUN. A DRY NW FLOW ALOFT AND MODERATING SURFACE FLOW SET THE STAGE FOR FAIR AND SEASONAL WEATHER NEXT WEEK. MAIN CONCERNS FOR THE NEXT FEW DAYS WILL BE THE CHANCE FOR SHOWERS TODAY AND THIS EVENING...POSSIBLE FROST AGAIN TONIGHT...AND THE UPCOMING ONSHORE...THEN OFFSHORE WINDS. AT THIS TIME...WE WILL KEEP A CHANCE FOR SNOW/RAIN SHOWERS...MAINLY SAN DIEGO COUNTY. 00Z ECMWF AND 06Z NAM BOTH SHOW SOME LIGHT PRECIP...ALONG WITH THE LATEST HRRR MODEL...MAINLY IN SAN DIEGO COUNTY TODAY. IN TERMS OF FROST...HEIGHTS/THICKNESS DO INCREASE A BIT AND THERE IS SOME WIND IN THE WAKE OF THE SHORT-WAVE. THE 4-KM NAM SHOWS SOME SFC WARMING AS WELL...SO WOULD EXPECT FROST TO REMAIN PATCHY...AND IN THE WIND-SHELTERED SPOTS. BASED ON A BLEND OF GUIDANCE...EXPECT BOTH THE ONSHORE AND THE OFFSHORE WINDS WILL BE AT OR BELOW ADVISORY STRENGTH IN THE WIND PRONE FOOTHILL/MTN/DESERT AREAS...BUT WILL MONITOR. IF THE LATEST RUNS OF THE ECMWF MODEL WERE TO VERIFY...THEY WOULD BE STRONGER. BUT GIVEN THE ECMWF PERFORMANCE THIS SEASON WITH THESE SHORT-WAVES IN NW FLOW...COULD WELL SEE SUBSEQUENT RUNS EASE OFF ON THIS MORE WESTWARD TRACK. && .AVIATION... 211000Z...A WEAK COASTAL EDDY WILL CONTINUE SCT-BKN LOW CLOUDS ALONG THE COAST THROUGH THIS MORNING...WITH BASES AROUND 3000 FT MSL AND TOPS TO 5000 FT MSL. PATCHY STRATUS WILL PENETRATE 25 TO 30 SM INLAND BY MID THIS MORNING. SKC AND P6SM VIS ARE FORECAST THIS AFTN THROUGH THE REMAINDER OF THE TAF PERIOD. ISOLATED SHOWERS POSSIBLE THROUGH THIS EVENING BUT LITTLE AVIATION IMPACT EXPECTED. && .MARINE... THE SMALL CRAFT ADVISORY FOR THE OUTER COASTAL WATERS HAS BEEN EXTENDED THROUGH 8 AM PST THIS MORNING DUE TO COMBINED SEAS REMAINING ABOVE 10 FEET. SEAS WILL LOWER THROUGH THE MORNING AS THE WIND CONTINUES TO DIMINISH. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...SMALL CRAFT ADVISORY UNTIL 8 AM PST THURSDAY FOR THE OUTER WATERS AND INCLUDING SAN CLEMENTE ISLAND. && $$ PUBLIC...JAD AVIATION/MARINE...JJT
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1051 PM EST FRI FEB 22 2013 .SYNOPSIS... A WARM FRONT IS EXPECTED TO LIFT NORTHWARD INTO SOUTHEAST GEORGIA THROUGH TONIGHT AS A WEDGE OF HIGH PRESSURE ANCHORS OVER THE CAROLINAS. A WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE FRONT ON SATURDAY THEN PUSH NORTHEAST. HIGH PRESSURE WILL BRIEFLY RETURN TO THE AREA ON SUNDAY BEFORE A WARM FRONT LIFTS NORTH ACROSS THE AREA LATE MONDAY AND MONDAY NIGHT....FOLLOWED BY THE PASSAGE OF A COLD FRONT EARLY TUESDAY. DRIER CONDITIONS ARE EXPECTED TO RETURN TO THE REGION BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... WILL ALLOW DENSE FOG ADVISORY TO EXPIRE AT 11 PM. VSBYS IN THE FOG ARE IMPROVING AS RAIN INTENSIFIES. THE FOG IS BECOMING RATHER THICK IN THE CHARLESTON METRO AREA...BUT AGAIN...EXPECT THIS TO BE TEMPORARY AS RAIN FILLS IN FROM THE SOUTHWEST. AT 23/02Z...THE WEDGE FRONT EXTENDING ROUGHLY ALONG A CAPE ROMAIN- HILTON HEAD-RICHMOND HILL-JESUP LINE. THE FRONT WILL MEANDER ALONG THE COAST FOR MUCH OF THE NIGHT BEFORE BUCKLING NORTH SLIGHTLY AS A WAVE OF LOW PRESSURE DEVELOPS ALONG IT. THE PRIMARY FORECAST CONCERNS THROUGH SUNRISE CENTER ON TEMPERATURES AS WELL AS THE POTENTIAL FOR HEAVY RAIN AND DENSE FOG. HEAVY RAIN...WATER VAPOR IMAGERY SHOWS A SHORTWAVE OVER FAR SOUTHEAST ALABAMA AND THE WESTERN FLORIDA PANHANDLE MOVING NORTHEAST. UPPER FORCING IS SLOWLY INCREASING AHEAD OF THIS FEATURE AS THE UPPER LEVEL FLOW BECOMES INCREASING MORE DIFLUENT ACROSS THE SOUTHEAST U.S. IN RESPONSE TO THE DIGGING LONG-WAVE TROUGH NOTED OVER THE CENTRAL/SOUTHERN PLAINS. CLOUD TOPS ARE SLOWLY COOLING OVER SOUTHERN GEORGIA AND NORTHERN FLORIDA IN RESPONSE WITH THE COVERAGE OF RAIN STEADILY EXPANDING/INTENSIFYING TO THE SOUTHWEST PER KVAX/KTLH RADAR COMPOSITES. RAIN IS EXPECTED TO OVERSPREAD MUCH OF THE FORECAST AREA AS THE SHORTWAVE APPROACHING SOUTHERN GEORGIA DRAWS CLOSER. PWATS IN EXCESS OF 1.5 INCHES /NEAR THE 99TH PERCENTILE FOR LATE FEBRUARY/ WILL SUPPORT MODERATE TO OCCASIONALLY HEAVY RAIN AT TIMES...BUT DO NOT ANTICIPATE ANY WIDESPREAD PROBLEMS WITH FLASH FLOODING. THE LATEST RUNS OF THE HIGHER RESOLUTION SHORT TERM MODELS INCLUDING THE RAP AND H3R ARE IN GOOD AGREEMENT IN SHOWING THE WEDGE FRONT MEANDERING VERY CLOSE TO THE COAST FOR A GOOD PORTION OF THE NIGHT AND ARE NOW FOCUSING THE AXIS OF HEAVIEST RAINS OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA THROUGH SUNRISE. WILL ADJUST FIRST PERIOD POPS TO NEAR 100 PERCENT FOR ALL AREAS...INCREASE QPF SLIGHTLY AND INCLUDE A RAIN HEAVY AT TIMES QUALIFIER. THE RISK FOR TSTMS AT THIS POINT LOOKS LOW...ALTHOUGH A RUMBLE OR TWO CAN NOT BE COMPLETELY RULED OUT. TEMPERATURES...PINNING DOWN TEMPERATURES IS PROVING TO BE NEAR IMPOSSIBLE. THE LATEST RAP SUGGESTS THE WEDGE FRONT WILL DRIFT SLIGHTLY EAST OVER THE NEXT FEW HOURS...POSSIBLY EMERGING OFF THE LOWER SOUTH CAROLINA COAST. WINDS HAVE RECENTLY TURNED NORTH AT THE CHARLESTON AIRPORT WHICH AGREES WELL WITH THE RAP WIND FIELDS. HAVE ADJUSTED HOURLY TEMPERATURES TO BETTER MATCH THE REPOSITIONING OF THE WEDGE FRONT THROUGH SUNRISE. ALSO LOWERED LOW TEMPERATURES DOWN QUITE A BIT IN SOME AREAS AS SOME LOCALES WELL INLAND WERE ALREADY BELOW FORECASTED MINIMUMS. COULD VERY WELL SEE A HUGE SWING IN TEMPERATURES...ESPECIALLY AT THE COAST... SHOULD THE WARM FRONT PUSHING BACK INLAND QUICKER THAN EXPECTED. LOWS WILL RANGE FROM THE LOWER 40S WELL INLAND TO AROUND 60 IN THE LUDOWICI- DARIEN-HINESVILLE CORRIDOR...BUT THIS IS A HIGHLY UNCERTAIN FORECAST. DENSE FOG...DENSE FOG REMAINS A PROBLEM ACROSS INTERIOR SOUTHEAST GEORGIA NORTH OF THE WEDGE FRONT AND ACROSS CHATHAM COUNTY WHERE SEA FOG LINGERS. EXTENDED THE DENSE FOG ADVISORY UNTIL 11 PM AS WARNING POINTS ARE STILL REPORTING VSBYS NEAR ZERO AT TIMES. VSBYS ARE IMPROVING A BIT WHERE RAIN FALLS SO ANTICIPATE THE ADVISORY WILL BE ALLOWED TO EXPIRE AT 11 PM. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SATURDAY AND SATURDAY NIGHT...A VERY LOW CONFIDENCE FORECAST TO START THE WEEKEND. A WEDGE FRONT WILL LIKELY BE POSITIONED SOMEWHERE ACROSS NORTHWEST PORTIONS OF THE FORECAST AREA AT THE START OF THE DAY AS A WAVE OF LOW PRESSURE DEVELOPS IN THE VICINITY OF CENTRAL GEORGIA. THE LOW WILL TRACK ALONG THE WEDGE FRONT THROUGH THE DAY AND SHIFT NORTHEAST OF THE AREA IN THE EVENING AS A TRAILING COLD FRONT SWINGS THROUGH FROM THE NORTHWEST. SHOWERS ARE EXPECTED TO BE ONGOING IN THE MORNING ACROSS NORTHWEST PORTIONS OF THE AREA...WITH THE GREATEST COVERAGE TOWARD THE MIDLANDS AND EAST-CENTRAL GEORGIA...AS A DISTURBANCE APPROACHES ALOFT AND ISENTROPIC LIFT STRENGTHENS. SOME SHOWERS SHOULD ALSO BE STREAMING INTO COASTAL SOUTH CAROLINA FROM THE ADJACENT COASTAL WATERS. THE BAND OF SHOWERS OVER THE MIDLANDS AND EAST-CENTRAL GEORGIA SHOULD SHIFT SOUTHEAST OVER THE AREA DURING THE AFTERNOON AND EARLY EVENING AS THE WAVE OF LOW PRESSURE PASSES...EVENTUALLY TAPERING OFF OVERNIGHT AS THE TRAILING COLD FRONT PUSHES OFFSHORE. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES...OR NEARLY 2 STANDARD DEVIATIONS ABOVE NORMAL...THE RAIN COULD BE HEAVY AT TIMES. THERE IS A POTENTIAL FOR SOME ISOLATED THUNDERSTORMS MAINLY IN THE AFTERNOON IN THE WARM SECTOR...WHICH SHOULD BE OVER PARTS OF SOUTHEAST GEORGIA AND COASTAL SOUTHEAST SOUTH CAROLINA. TEMPERATURES WILL BE VERY DIFFICULT TO FORECAST...WITH A VERY LARGE GRADIENT EXPECTED OVER THE AREA. WITH THE WEDGE EXPECTED TO PERSIST ACROSS FAR NORTHWEST PORTIONS OF THE AREA HIGHS THERE ARE ONLY FORECAST TO BE IN THE LOWER 50S...BUT WITHIN THE WARM SECTOR HIGHS COULD BE IN THE LOWER TO MID 70S ACROSS NORTH COASTAL GEORGIA AND AREAS CLOSER TO THE ALTAMAHA. PINNING DOWN THE EXACT POSITION OF THE WEDGE IS SO DIFFICULT THAT TEMPERATURES IN SOME AREAS COULD BE OFF BY AS MUCH AS 10 DEGREES FROM THE CURRENT FORECAST. SUNDAY...HIGH PRESSURE WILL BRIEFLY BUILD OVER THE REGION FROM THE NORTHWEST WITH RAIN-FREE CONDITIONS EXPECTED. TEMPERATURES COULD REACH HIGHS AROUND 70 WITH A DOWNSLOPE WIND COMPONENT ALOFT UNDER MOSTLY SUNNY TO PARTLY CLOUDY SKIES. SUNDAY NIGHT AND MONDAY...A WARM FRONT EXTENDING FROM A STORM SYSTEM OVER THE MID-MISSISSIPPI VALLEY WILL SLOWLY LIFT NORTHWARD TOWARD THE AREA. IT APPEARS THE WARM FRONT COULD ENTER PARTS OF SOUTHEAST GEORGIA LATE IN THE DAY ON MONDAY. STRENGTHENING ISENTROPIC ASCENT AND DEEP MOISTURE AHEAD OF THE WARM FRONT SHOULD ALLOW SCATTERED TO NUMEROUS SHOWERS TO DEVELOP FROM THE SOUTH SUNDAY NIGHT...THEN BECOME NUMEROUS TO WIDESPREAD ACROSS THE AREA ON MONDAY. SOME ISOLATED THUNDERSTORMS COULD ALSO DEVELOP ACROSS SOUTHERN AREAS LATER IN THE DAY DEPENDING ON THE TIMING OF THE FRONT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... WET CONDITIONS WILL PERSIST OVER THE FORECAST AREA THROUGH EARLY NEXT WEEK AS A SFC LOW SHIFTS ACROSS THE SOUTHEAST. CONDITIONS WILL THEN BEGIN TO DRY AS THE SFC LOW SHIFTS OFF THE MID ATLANTIC COAST AND IS FOLLOWED BY HIGH PRESSURE OVER THE SOUTHEAST. A COOL AND DRY TREND SHOULD THEN TAKE PLACE THROUGH MUCH OF NEXT WEEK AS A MID/UPPER LVL LOW BECOMES CUT OFF OVER THE NORTHEASTERN UNITED STATE. OVERALL...AFTERNOON HIGHS WILL RANGE FROM THE MID 60S ON TUESDAY TO THE UPPER 50S BY THURSDAY. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 30S/LOWER 40S ON TUESDAY TO MID 30S/LOWER 40S BY THURSDAY. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... BOTH TERMINALS WILL BE IFR OR LOWER FOR MOST OF THE NIGHT AS MORE DEEP MOISTURE CONTINUES ITS TRACK UP THE COAST. DEGRADED VISIBILITIES DUE TO FOG AND RAIN ARE ALSO A POSSIBILITY AS THE WARM FRONT AND MINOR SHORTWAVE IMPULSES MOVE UP INTO THE AREA. CONDITIONS LOOK TO SLIGHTLY IMPROVE BY DAYBREAK AS THE WARM FRONT LIFTS NORTH OF KSAV AND WIND SPEEDS PICK UP...HOWEVER...MODEL SOUNDINGS ARE KEEPING THE DEEP MOISTURE IN PLACE FOR THE DAY. EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS WILL LIKELY CONTINUE THROUGH SATURDAY NIGHT DUE TO LOW CEILINGS AND REDUCED VISIBILITIES. VFR CONDITIONS WILL PREVAIL SUNDAY...THEN MVFR OR LOWER CONDITIONS SHOULD RETURN SUNDAY NIGHT THROUGH MONDAY NIGHT. VFR CONDITIONS WILL THEN PREVAIL TUESDAY INTO WEDNESDAY. && .MARINE... SAVANNAH PILOT BOAT REPORTED VSBYS NEAR ZERO IN DENSE SEA FOG AS FAR OFFSHORE AS BUOY CHARLIE. HILTON HEAD AIRPORT ALSO REPORTING A CEILING NEAR 100 FT SUGGESTING FOG IS LIKELY NOT TOO FAR OFFSHORE. HAVE ISSUED A DENSE FOG ADVISORY FOR AMZ352-354 UNTIL 1 AM. ITS UNCLEAR HOW MUCH VSBYS WILL IMPROVE AS RAIN FILLS IN...SO ONLY TOOK THE ADVISORY UNTIL 1 AM. ADJUSTMENTS WILL BE NEEDED OVER THE NEXT FEW HRS. ADJUSTED WINDS OVER THE SOUTH CAROLINA WATERS TO NORTH OVERNIGHT AS RAP GUIDANCE SUGGESTS THE WEDGE FRONT WILL DROP SOUTH. ALSO NUDGED THE START TIME FOR THE SMALL CRAFT ADVISORY TO THE CURRENT TIME OVER THE GEORGIA OFFSHORE WATERS. SATURDAY THROUGH TUESDAY...SMALL CRAFT ADVISORY CONDITIONS WILL PERSIST OVER OUTER GEORGIA WATERS THROUGH 5 PM SATURDAY AS A WEDGE OF HIGH PRESSURE INLAND MAINTAINS AN ENHANCED PRESSURE GRADIENT OVER THESE WATERS THROUGH MUCH OF THE DAY AND SEAS REMAIN ELEVATED. THE WEDGE WILL THEN BREAK DOWN LATE AS A SFC LOW TRACKS THROUGH THE SOUTHEASTERN UNITED STATES AND INTO THE MID ATLANTIC. EXPECT SOUTHERLY WINDS TO BECOME WEST AS A TRAILING COLD FRONT SHIFTS THROUGH THE WATERS INTO EARLY SUNDAY. CONDITIONS WILL THEN REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR ALL WATERS THROUGH EARLY MONDAY AS HIGH PRESSURE DOMINANTS THE PATTERN. WINDS AND SEAS WILL THEN INCREASE MONDAY AFTERNOON INTO TUESDAY AS A WARM FRONT LIFTS NORTH AND THEN IS FOLLOWED BY A SFC LOW TRACKING OVER THE WATERS LATE. WE COULD SEE SMALL CRAFT ADVISORY CONDITIONS AS THE PRESSURE GRADIENT BECOMES ENHANCED OVER THE WATERS DURING THIS TIME. && .HYDROLOGY... STORM TOTAL RAINFALL AMOUNTS OF 3-6 INCHES WITH LOCALLY HIGHER AMOUNTS ARE LIKELY TO OCCUR ACROSS THE REGION THROUGH EARLY NEXT WEEK BRINGING MORE RELIEF TO DROUGHT STRICKEN AREAS. THESE RAINS FALLING INTO ALREADY SWOLLEN RIVERS WILL YIELD ADDITIONAL RISES AND RIVERINE FLOODING THROUGH THE END OF NEXT WEEK. ADDITIONAL RIVER FLOOD WARNINGS ARE LIKELY PER THE LATEST SHORT TERM ENSEMBLE HYDROLOGIC FORECASTS AND RIVER GUIDANCE FROM THE SOUTHEAST RIVER FORECAST CENTER. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...DENSE FOG ADVISORY UNTIL 1 AM EST SATURDAY FOR AMZ352-354. SMALL CRAFT ADVISORY UNTIL 5 PM EST SATURDAY FOR AMZ374. && $$ ST/BDC
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
954 PM EST FRI FEB 22 2013 .SYNOPSIS... A WARM FRONT IS EXPECTED TO LIFT NORTHWARD INTO SOUTHEAST GEORGIA THROUGH TONIGHT AS A WEDGE OF HIGH PRESSURE ANCHORS OVER THE CAROLINAS. A WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE FRONT ON SATURDAY THEN PUSH NORTHEAST. HIGH PRESSURE WILL BRIEFLY RETURN TO THE AREA ON SUNDAY BEFORE A WARM FRONT LIFTS NORTH ACROSS THE AREA LATE MONDAY AND MONDAY NIGHT....FOLLOWED BY THE PASSAGE OF A COLD FRONT EARLY TUESDAY. DRIER CONDITIONS ARE EXPECTED TO RETURN TO THE REGION BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... VERY FEW CHANGES WERE MADE TO THE GOING FORECAST EXCEPT TO EXTEND THE DENSE FOG ADVISORY FOR ANOTHER HOUR. WARNING POINTS STILL INDICATE VSBYS ARE QUITE LOW...NEAR ZERO AT TIMES. VSBYS SHOULD IMPROVE OVER THE NEXT HOURS AS RAIN FILLS IN FROM THE SOUTHWEST. AT 23/02Z...THE WEDGE FRONT EXTENDING ROUGHLY ALONG A CAPE ROMAIN- HILTON HEAD-RICHMOND HILL-JESUP LINE. THE FRONT WILL MEANDER ALONG THE COAST FOR MUCH OF THE NIGHT BEFORE BUCKLING NORTH SLIGHTLY AS A WAVE OF LOW PRESSURE DEVELOPS ALONG IT. THE PRIMARY FORECAST CONCERNS THROUGH SUNRISE CENTER ON TEMPERATURES AS WELL AS THE POTENTIAL FOR HEAVY RAIN AND DENSE FOG. HEAVY RAIN...WATER VAPOR IMAGERY SHOWS A SHORTWAVE OVER FAR SOUTHEAST ALABAMA AND THE WESTERN FLORIDA PANHANDLE MOVING NORTHEAST. UPPER FORCING IS SLOWLY INCREASING AHEAD OF THIS FEATURE AS THE UPPER LEVEL FLOW BECOMES INCREASING MORE DIFLUENT ACROSS THE SOUTHEAST U.S. IN RESPONSE TO THE DIGGING LONG-WAVE TROUGH NOTED OVER THE CENTRAL/SOUTHERN PLAINS. CLOUD TOPS ARE SLOWLY COOLING OVER SOUTHERN GEORGIA AND NORTHERN FLORIDA IN RESPONSE WITH THE COVERAGE OF RAIN STEADILY EXPANDING/INTENSIFYING TO THE SOUTHWEST PER KVAX/KTLH RADAR COMPOSITES. RAIN IS EXPECTED TO OVERSPREAD MUCH OF THE FORECAST AREA AS THE SHORTWAVE APPROACHING SOUTHERN GEORGIA DRAWS CLOSER. PWATS IN EXCESS OF 1.5 INCHES /NEAR THE 99TH PERCENTILE FOR LATE FEBRUARY/ WILL SUPPORT MODERATE TO OCCASIONALLY HEAVY RAIN AT TIMES...BUT DO NOT ANTICIPATE ANY WIDESPREAD PROBLEMS WITH FLASH FLOODING. THE LATEST RUNS OF THE HIGHER RESOLUTION SHORT TERM MODELS INCLUDING THE RAP AND H3R ARE IN GOOD AGREEMENT IN SHOWING THE WEDGE FRONT MEANDERING VERY CLOSE TO THE COAST FOR A GOOD PORTION OF THE NIGHT AND ARE NOW FOCUSING THE AXIS OF HEAVIEST RAINS OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA THROUGH SUNRISE. WILL ADJUST FIRST PERIOD POPS TO NEAR 100 PERCENT FOR ALL AREAS...INCREASE QPF SLIGHTLY AND INCLUDE A RAIN HEAVY AT TIMES QUALIFIER. THE RISK FOR TSTMS AT THIS POINT LOOKS LOW...ALTHOUGH A RUMBLE OR TWO CAN NOT BE COMPLETELY RULED OUT. TEMPERATURES...PINNING DOWN TEMPERATURES IS PROVING TO BE NEAR IMPOSSIBLE. THE LATEST RAP SUGGESTS THE WEDGE FRONT WILL DRIFT SLIGHTLY EAST OVER THE NEXT FEW HOURS...POSSIBLY EMERGING OFF THE LOWER SOUTH CAROLINA COAST. WINDS HAVE RECENTLY TURNED NORTH AT THE CHARLESTON AIRPORT WHICH AGREES WELL WITH THE RAP WIND FIELDS. HAVE ADJUSTED HOURLY TEMPERATURES TO BETTER MATCH THE REPOSITIONING OF THE WEDGE FRONT THROUGH SUNRISE. ALSO LOWERED LOW TEMPERATURES DOWN QUITE A BIT IN SOME AREAS AS SOME LOCALES WELL INLAND WERE ALREADY BELOW FORECASTED MINIMUMS. COULD VERY WELL SEE A HUGE SWING IN TEMPERATURES...ESPECIALLY AT THE COAST... SHOULD THE WARM FRONT PUSHING BACK INLAND QUICKER THAN EXPECTED. LOWS WILL RANGE FROM THE LOWER 40S WELL INLAND TO AROUND 60 IN THE LUDOWICI- DARIEN-HINESVILLE CORRIDOR...BUT THIS IS A HIGHLY UNCERTAIN FORECAST. DENSE FOG...DENSE FOG REMAINS A PROBLEM ACROSS INTERIOR SOUTHEAST GEORGIA NORTH OF THE WEDGE FRONT AND ACROSS CHATHAM COUNTY WHERE SEA FOG LINGERS. EXTENDED THE DENSE FOG ADVISORY UNTIL 11 PM AS WARNING POINTS ARE STILL REPORTING VSBYS NEAR ZERO AT TIMES. VSBYS ARE IMPROVING A BIT WHERE RAIN FALLS SO ANTICIPATE THE ADVISORY WILL BE ALLOWED TO EXPIRE AT 11 PM. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SATURDAY AND SATURDAY NIGHT...A VERY LOW CONFIDENCE FORECAST TO START THE WEEKEND. A WEDGE FRONT WILL LIKELY BE POSITIONED SOMEWHERE ACROSS NORTHWEST PORTIONS OF THE FORECAST AREA AT THE START OF THE DAY AS A WAVE OF LOW PRESSURE DEVELOPS IN THE VICINITY OF CENTRAL GEORGIA. THE LOW WILL TRACK ALONG THE WEDGE FRONT THROUGH THE DAY AND SHIFT NORTHEAST OF THE AREA IN THE EVENING AS A TRAILING COLD FRONT SWINGS THROUGH FROM THE NORTHWEST. SHOWERS ARE EXPECTED TO BE ONGOING IN THE MORNING ACROSS NORTHWEST PORTIONS OF THE AREA...WITH THE GREATEST COVERAGE TOWARD THE MIDLANDS AND EAST-CENTRAL GEORGIA...AS A DISTURBANCE APPROACHES ALOFT AND ISENTROPIC LIFT STRENGTHENS. SOME SHOWERS SHOULD ALSO BE STREAMING INTO COASTAL SOUTH CAROLINA FROM THE ADJACENT COASTAL WATERS. THE BAND OF SHOWERS OVER THE MIDLANDS AND EAST-CENTRAL GEORGIA SHOULD SHIFT SOUTHEAST OVER THE AREA DURING THE AFTERNOON AND EARLY EVENING AS THE WAVE OF LOW PRESSURE PASSES...EVENTUALLY TAPERING OFF OVERNIGHT AS THE TRAILING COLD FRONT PUSHES OFFSHORE. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES...OR NEARLY 2 STANDARD DEVIATIONS ABOVE NORMAL...THE RAIN COULD BE HEAVY AT TIMES. THERE IS A POTENTIAL FOR SOME ISOLATED THUNDERSTORMS MAINLY IN THE AFTERNOON IN THE WARM SECTOR...WHICH SHOULD BE OVER PARTS OF SOUTHEAST GEORGIA AND COASTAL SOUTHEAST SOUTH CAROLINA. TEMPERATURES WILL BE VERY DIFFICULT TO FORECAST...WITH A VERY LARGE GRADIENT EXPECTED OVER THE AREA. WITH THE WEDGE EXPECTED TO PERSIST ACROSS FAR NORTHWEST PORTIONS OF THE AREA HIGHS THERE ARE ONLY FORECAST TO BE IN THE LOWER 50S...BUT WITHIN THE WARM SECTOR HIGHS COULD BE IN THE LOWER TO MID 70S ACROSS NORTH COASTAL GEORGIA AND AREAS CLOSER TO THE ALTAMAHA. PINNING DOWN THE EXACT POSITION OF THE WEDGE IS SO DIFFICULT THAT TEMPERATURES IN SOME AREAS COULD BE OFF BY AS MUCH AS 10 DEGREES FROM THE CURRENT FORECAST. SUNDAY...HIGH PRESSURE WILL BRIEFLY BUILD OVER THE REGION FROM THE NORTHWEST WITH RAIN-FREE CONDITIONS EXPECTED. TEMPERATURES COULD REACH HIGHS AROUND 70 WITH A DOWNSLOPE WIND COMPONENT ALOFT UNDER MOSTLY SUNNY TO PARTLY CLOUDY SKIES. SUNDAY NIGHT AND MONDAY...A WARM FRONT EXTENDING FROM A STORM SYSTEM OVER THE MID-MISSISSIPPI VALLEY WILL SLOWLY LIFT NORTHWARD TOWARD THE AREA. IT APPEARS THE WARM FRONT COULD ENTER PARTS OF SOUTHEAST GEORGIA LATE IN THE DAY ON MONDAY. STRENGTHENING ISENTROPIC ASCENT AND DEEP MOISTURE AHEAD OF THE WARM FRONT SHOULD ALLOW SCATTERED TO NUMEROUS SHOWERS TO DEVELOP FROM THE SOUTH SUNDAY NIGHT...THEN BECOME NUMEROUS TO WIDESPREAD ACROSS THE AREA ON MONDAY. SOME ISOLATED THUNDERSTORMS COULD ALSO DEVELOP ACROSS SOUTHERN AREAS LATER IN THE DAY DEPENDING ON THE TIMING OF THE FRONT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... WET CONDITIONS WILL PERSIST OVER THE FORECAST AREA THROUGH EARLY NEXT WEEK AS A SFC LOW SHIFTS ACROSS THE SOUTHEAST. CONDITIONS WILL THEN BEGIN TO DRY AS THE SFC LOW SHIFTS OFF THE MID ATLANTIC COAST AND IS FOLLOWED BY HIGH PRESSURE OVER THE SOUTHEAST. A COOL AND DRY TREND SHOULD THEN TAKE PLACE THROUGH MUCH OF NEXT WEEK AS A MID/UPPER LVL LOW BECOMES CUT OFF OVER THE NORTHEASTERN UNITED STATE. OVERALL...AFTERNOON HIGHS WILL RANGE FROM THE MID 60S ON TUESDAY TO THE UPPER 50S BY THURSDAY. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 30S/LOWER 40S ON TUESDAY TO MID 30S/LOWER 40S BY THURSDAY. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... BOTH TERMINALS WILL BE IFR OR LOWER FOR MOST OF THE NIGHT AS MORE DEEP MOISTURE CONTINUES ITS TRACK UP THE COAST. DEGRADED VISIBILITIES DUE TO FOG AND RAIN ARE ALSO A POSSIBILITY AS THE WARM FRONT AND MINOR SHORTWAVE IMPULSES MOVE UP INTO THE AREA. CONDITIONS LOOK TO SLIGHTLY IMPROVE BY DAYBREAK AS THE WARM FRONT LIFTS NORTH OF KSAV AND WIND SPEEDS PICK UP...HOWEVER...MODEL SOUNDINGS ARE KEEPING THE DEEP MOISTURE IN PLACE FOR THE DAY. EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS WILL LIKELY CONTINUE THROUGH SATURDAY NIGHT DUE TO LOW CEILINGS AND REDUCED VISIBILITIES. VFR CONDITIONS WILL PREVAIL SUNDAY...THEN MVFR OR LOWER CONDITIONS SHOULD RETURN SUNDAY NIGHT THROUGH MONDAY NIGHT. VFR CONDITIONS WILL THEN PREVAIL TUESDAY INTO WEDNESDAY. && .MARINE... SAVANNAH PILOT BOAT REPORTED VSBYS NEAR ZERO IN DENSE SEA FOG AS FAR OFFSHORE AS BUOY CHARLIE. HILTON HEAD AIRPORT ALSO REPORTING A CEILING NEAR 100 FT SUGGESTING FOG IS LIKELY NOT TOO FAR OFFSHORE. HAVE ISSUED A DENSE FOG ADVISORY FOR AMZ352-354 UNTIL 1 AM. ITS UNCLEAR HOW MUCH VSBYS WILL IMPROVE AS RAIN FILLS IN...SO ONLY TOOK THE ADVISORY UNTIL 1 AM. ADJUSTMENTS WILL BE NEEDED OVER THE NEXT FEW HRS. ADJUSTED WINDS OVER THE SOUTH CAROLINA WATERS TO NORTH OVERNIGHT AS RAP GUIDANCE SUGGESTS THE WEDGE FRONT WILL DROP SOUTH. ALSO NUDGED THE START TIME FOR THE SMALL CRAFT ADVISORY TO THE CURRENT TIME OVER THE GEORGIA OFFSHORE WATERS. SATURDAY THROUGH TUESDAY...SMALL CRAFT ADVISORY CONDITIONS WILL PERSIST OVER OUTER GEORGIA WATERS THROUGH 5 PM SATURDAY AS A WEDGE OF HIGH PRESSURE INLAND MAINTAINS AN ENHANCED PRESSURE GRADIENT OVER THESE WATERS THROUGH MUCH OF THE DAY AND SEAS REMAIN ELEVATED. THE WEDGE WILL THEN BREAK DOWN LATE AS A SFC LOW TRACKS THROUGH THE SOUTHEASTERN UNITED STATES AND INTO THE MID ATLANTIC. EXPECT SOUTHERLY WINDS TO BECOME WEST AS A TRAILING COLD FRONT SHIFTS THROUGH THE WATERS INTO EARLY SUNDAY. CONDITIONS WILL THEN REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR ALL WATERS THROUGH EARLY MONDAY AS HIGH PRESSURE DOMINANTS THE PATTERN. WINDS AND SEAS WILL THEN INCREASE MONDAY AFTERNOON INTO TUESDAY AS A WARM FRONT LIFTS NORTH AND THEN IS FOLLOWED BY A SFC LOW TRACKING OVER THE WATERS LATE. WE COULD SEE SMALL CRAFT ADVISORY CONDITIONS AS THE PRESSURE GRADIENT BECOMES ENHANCED OVER THE WATERS DURING THIS TIME. && .HYDROLOGY... STORM TOTAL RAINFALL AMOUNTS OF 3-6 INCHES WITH LOCALLY HIGHER AMOUNTS ARE LIKELY TO OCCUR ACROSS THE REGION THROUGH EARLY NEXT WEEK BRINGING MORE RELIEF TO DROUGHT STRICKEN AREAS. THESE RAINS FALLING INTO ALREADY SWOLLEN RIVERS WILL YIELD ADDITIONAL RISES AND RIVERINE FLOODING THROUGH THE END OF NEXT WEEK. ADDITIONAL RIVER FLOOD WARNINGS ARE LIKELY PER THE LATEST SHORT TERM ENSEMBLE HYDROLOGIC FORECASTS AND RIVER GUIDANCE FROM THE SOUTHEAST RIVER FORECAST CENTER. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...DENSE FOG ADVISORY UNTIL 11 PM EST THIS EVENING FOR GAZ087-088- 099-100-117>119. SC...NONE. MARINE...DENSE FOG ADVISORY UNTIL 1 AM EST SATURDAY FOR AMZ352-354. SMALL CRAFT ADVISORY UNTIL 5 PM EST SATURDAY FOR AMZ374. && $$ ST/BDC
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
816 PM EST FRI FEB 22 2013 ...DENSE FOG AFFECTING SOME AREAS TONIGHT... .SYNOPSIS... A WARM FRONT IS EXPECTED TO LIFT NORTHWARD INTO SOUTHEAST GEORGIA THROUGH TONIGHT AS A WEDGE OF HIGH PRESSURE ANCHORS OVER THE CAROLINAS. A WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE FRONT ON SATURDAY THEN PUSH NORTHEAST. HIGH PRESSURE WILL BRIEFLY RETURN TO THE AREA ON SUNDAY BEFORE A WARM FRONT LIFTS NORTH ACROSS THE AREA LATE MONDAY AND MONDAY NIGHT....FOLLOWED BY THE PASSAGE OF A COLD FRONT EARLY TUESDAY. DRIER CONDITIONS ARE EXPECTED TO RETURN TO THE REGION BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AT 22/23Z...THE WEDGE FRONT EXTENDING ROUGHLY ALONG A GEORGETOWN- WEST ASHLEY-BEAUFORT-SAVANNAH-JESUP LINE. NORTH OF THE FRONT... TEMPERATURES DROP OFF RAPIDLY INTO THE LOWER 40S TO MID 50S WHILE FARTHER SOUTH TEMPERATURES WERE IN THE UPPER 50S TO AROUND 70. THE FRONT WILL MEANDER ALONG THE COAST FOR MUCH OF THE NIGHT BEFORE BUCKLING NORTH SLIGHTLY AS A WAVE OF LOW PRESSURE DEVELOPS ALONG IT. THE PRIMARY FORECAST CONCERNS THROUGH SUNRISE CENTER ON TEMPERATURES AS WELL AS THE POTENTIAL FOR HEAVY RAIN AND DENSE FOG. HEAVY RAIN...WATER VAPOR IMAGERY SHOWS A SHORTWAVE OVER FAR SOUTHEAST ALABAMA AND THE WESTERN FLORIDA PANHANDLE MOVING NORTHEAST. UPPER FORCING IS SLOWLY INCREASING AHEAD OF THIS FEATURE AS THE UPPER LEVEL FLOW BECOMES INCREASING MORE DIFLUENT ACROSS THE SOUTHEAST U.S. IN RESPONSE TO THE DIGGING LONG-WAVE TROUGH NOTED OVER THE CENTRAL/SOUTHERN PLAINS. CLOUD TOPS ARE SLOWLY COOLING OVER SOUTHERN GEORGIA AND NORTHERN FLORIDA IN RESPONSE WITH THE COVERAGE OF RAIN STEADILY EXPANDING/INTENSIFYING TO THE SOUTHWEST PER KVAX/KTLH RADAR COMPOSITES. RAIN IS EXPECTED TO OVERSPREAD MUCH OF THE FORECAST AREA OVER THE NEXT SEVERAL HOURS AS THE SHORTWAVE APPROACHING SOUTHERN GEORGIA DRAWS CLOSER. PWATS IN EXCESS OF 1.5 INCHES /NEAR THE 99TH PERCENTILE FOR LATE FEBRUARY/ WILL SUPPORT MODERATE TO OCCASIONALLY HEAVY RAIN AT TIMES...BUT DO ANTICIPATE ANY WIDESPREAD PROBLEMS WITH FLASH FLOODING. THE LATEST RUNS OF THE HIGHER RESOLUTION SHORT TERM MODELS INCLUDING THE RAP AND H3R ARE IN GOOD AGREEMENT IN SHOWING THE WEDGE FRONT MEANDERING VERY CLOSE TO THE COAST FOR A GOOD PORTION OF THE NIGHT AND ARE NOW FOCUSING THE AXIS OF HEAVIEST RAINS OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA THROUGH SUNRISE. WILL ADJUST FIRST PERIOD POPS TO NEAR 100 PERCENT FOR ALL AREAS...INCREASE QPF SLIGHTLY AND INCLUDE A RAIN HEAVY AT TIMES QUALIFIER. THE RISK FOR TSTMS AT THIS POINT LOOKS LOW...ALTHOUGH A RUMBLE OR TWO CAN NOT BE COMPLETELY RULED OUT. TEMPERATURES...PINNING DOWN TEMPERATURES IS PROVING TO BE NEAR IMPOSSIBLE. THE LATEST RAP SUGGESTS THE WEDGE FRONT WILL DRIFT SLIGHTLY EAST OVER THE NEXT FEW HOURS...POSSIBLY EMERGING OFF THE LOWER SOUTH CAROLINA COAST. WINDS HAVE RECENTLY TURNED NORTH AT THE CHARLESTON AIRPORT WHICH AGREES WELL WITH THE RAP WIND FIELDS. HAVE ADJUSTED HOURLY TEMPERATURES TO BETTER MATCH THE REPOSITIONING OF THE WEDGE FRONT THROUGH SUNRISE. ALSO LOWERED LOW TEMPERATURES DOWN QUITE A BIT IN SOME AREAS AS SOME LOCALES WELL INLAND WERE ALREADY BELOW FORECASTED MINIMUMS. COULD VERY WELL SEE A HUGE SWING IN TEMPERATURES...ESPECIALLY AT THE COAST... SHOULD THE WARM FRONT PUSHING BACK INLAND QUICKER THAN EXPECTED. LOWS WILL RANGE FROM THE LOWER 40S WELL INLAND TO AROUND 60 IN THE LUDOWICI- DARIEN-HINESVILLE CORRIDOR...BUT THIS IS A HIGHLY UNCERTAIN FORECAST. DENSE FOG...REPORTS FROM COUNTY WARNING POINTS AND THE SAVANNAH MEDIA INDICATE DENSE FOG IS BECOMING QUITE WIDESPREAD ACROSS FAR INTERIOR SOUTHEAST GEORGIA NORTH OF THE WEDGE FRONT. VISIBILITIES WERE BEING REPORTED TO JUST A FEW FEET IN SOME LOCATIONS. HAVE HOISTED A DENSE FOG ADVISORY UNTIL 10 PM FOR CANDLER...SCREVEN... JENKINS AND BULLOCH. EXPECT CONDITIONS TO IMPROVE AS RAIN INCREASES FROM THE SOUTHWEST. AN ADVISORY HAS ALSO BEEN POSTED FOR INLAND CHATHAM...COASTAL CHATHAM AND COASTAL BRYAN WHERE SEA FOG CONTINUES TO PUSH INLAND. SIMILARLY...EXPECT CONDITIONS TO IMPROVE THERE ONCE RAIN MOVES IN BY 10 PM. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SATURDAY AND SATURDAY NIGHT...A VERY LOW CONFIDENCE FORECAST TO START THE WEEKEND. A WEDGE FRONT WILL LIKELY BE POSITIONED SOMEWHERE ACROSS NORTHWEST PORTIONS OF THE FORECAST AREA AT THE START OF THE DAY AS A WAVE OF LOW PRESSURE DEVELOPS IN THE VICINITY OF CENTRAL GEORGIA. THE LOW WILL TRACK ALONG THE WEDGE FRONT THROUGH THE DAY AND SHIFT NORTHEAST OF THE AREA IN THE EVENING AS A TRAILING COLD FRONT SWINGS THROUGH FROM THE NORTHWEST. SHOWERS ARE EXPECTED TO BE ONGOING IN THE MORNING ACROSS NORTHWEST PORTIONS OF THE AREA...WITH THE GREATEST COVERAGE TOWARD THE MIDLANDS AND EAST-CENTRAL GEORGIA...AS A DISTURBANCE APPROACHES ALOFT AND ISENTROPIC LIFT STRENGTHENS. SOME SHOWERS SHOULD ALSO BE STREAMING INTO COASTAL SOUTH CAROLINA FROM THE ADJACENT COASTAL WATERS. THE BAND OF SHOWERS OVER THE MIDLANDS AND EAST-CENTRAL GEORGIA SHOULD SHIFT SOUTHEAST OVER THE AREA DURING THE AFTERNOON AND EARLY EVENING AS THE WAVE OF LOW PRESSURE PASSES...EVENTUALLY TAPERING OFF OVERNIGHT AS THE TRAILING COLD FRONT PUSHES OFFSHORE. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES...OR NEARLY 2 STANDARD DEVIATIONS ABOVE NORMAL...THE RAIN COULD BE HEAVY AT TIMES. THERE IS A POTENTIAL FOR SOME ISOLATED THUNDERSTORMS MAINLY IN THE AFTERNOON IN THE WARM SECTOR...WHICH SHOULD BE OVER PARTS OF SOUTHEAST GEORGIA AND COASTAL SOUTHEAST SOUTH CAROLINA. TEMPERATURES WILL BE VERY DIFFICULT TO FORECAST...WITH A VERY LARGE GRADIENT EXPECTED OVER THE AREA. WITH THE WEDGE EXPECTED TO PERSIST ACROSS FAR NORTHWEST PORTIONS OF THE AREA HIGHS THERE ARE ONLY FORECAST TO BE IN THE LOWER 50S...BUT WITHIN THE WARM SECTOR HIGHS COULD BE IN THE LOWER TO MID 70S ACROSS NORTH COASTAL GEORGIA AND AREAS CLOSER TO THE ALTAMAHA. PINNING DOWN THE EXACT POSITION OF THE WEDGE IS SO DIFFICULT THAT TEMPERATURES IN SOME AREAS COULD BE OFF BY AS MUCH AS 10 DEGREES FROM THE CURRENT FORECAST. SUNDAY...HIGH PRESSURE WILL BRIEFLY BUILD OVER THE REGION FROM THE NORTHWEST WITH RAIN-FREE CONDITIONS EXPECTED. TEMPERATURES COULD REACH HIGHS AROUND 70 WITH A DOWNSLOPE WIND COMPONENT ALOFT UNDER MOSTLY SUNNY TO PARTLY CLOUDY SKIES. SUNDAY NIGHT AND MONDAY...A WARM FRONT EXTENDING FROM A STORM SYSTEM OVER THE MID-MISSISSIPPI VALLEY WILL SLOWLY LIFT NORTHWARD TOWARD THE AREA. IT APPEARS THE WARM FRONT COULD ENTER PARTS OF SOUTHEAST GEORGIA LATE IN THE DAY ON MONDAY. STRENGTHENING ISENTROPIC ASCENT AND DEEP MOISTURE AHEAD OF THE WARM FRONT SHOULD ALLOW SCATTERED TO NUMEROUS SHOWERS TO DEVELOP FROM THE SOUTH SUNDAY NIGHT...THEN BECOME NUMEROUS TO WIDESPREAD ACROSS THE AREA ON MONDAY. SOME ISOLATED THUNDERSTORMS COULD ALSO DEVELOP ACROSS SOUTHERN AREAS LATER IN THE DAY DEPENDING ON THE TIMING OF THE FRONT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... WET CONDITIONS WILL PERSIST OVER THE FORECAST AREA THROUGH EARLY NEXT WEEK AS A SFC LOW SHIFTS ACROSS THE SOUTHEAST. CONDITIONS WILL THEN BEGIN TO DRY AS THE SFC LOW SHIFTS OFF THE MID ATLANTIC COAST AND IS FOLLOWED BY HIGH PRESSURE OVER THE SOUTHEAST. A COOL AND DRY TREND SHOULD THEN TAKE PLACE THROUGH MUCH OF NEXT WEEK AS A MID/UPPER LVL LOW BECOMES CUT OFF OVER THE NORTHEASTERN UNITED STATE. OVERALL...AFTERNOON HIGHS WILL RANGE FROM THE MID 60S ON TUESDAY TO THE UPPER 50S BY THURSDAY. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 30S/LOWER 40S ON TUESDAY TO MID 30S/LOWER 40S BY THURSDAY. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... BOTH TERMINALS WILL BE IFR OR LOWER FOR MOST OF THE NIGHT AS MORE DEEP MOISTURE CONTINUES ITS TRACK UP THE COAST. DEGRADED VISIBILITIES DUE TO FOG AND RAIN ARE ALSO A POSSIBILITY AS THE WARM FRONT AND MINOR SHORTWAVE IMPULSES MOVE UP INTO THE AREA. CONDITIONS LOOK TO SLIGHTLY IMPROVE BY DAYBREAK AS THE WARM FRONT LIFTS NORTH OF KSAV AND WIND SPEEDS PICK UP...HOWEVER...MODEL SOUNDINGS ARE KEEPING THE DEEP MOISTURE IN PLACE FOR THE DAY. EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS WILL LIKELY CONTINUE THROUGH SATURDAY NIGHT DUE TO LOW CEILINGS AND REDUCED VISIBILITIES. VFR CONDITIONS WILL PREVAIL SUNDAY...THEN MVFR OR LOWER CONDITIONS SHOULD RETURN SUNDAY NIGHT THROUGH MONDAY NIGHT. VFR CONDITIONS WILL THEN PREVAIL TUESDAY INTO WEDNESDAY. && .MARINE... SAVANNAH PILOT BOAT REPORTED VSBYS NEAR ZERO IN DENSE SEA FOG AS FAR OFFSHORE AS BUOY CHARLIE. HILTON HEAD AIRPORT ALSO REPORTING A CEILING NEAR 100 FT SUGGESTING FOG IS LIKELY NOT TOO FAR OFFSHORE. HAVE ISSUED A DENSE FOG ADVISORY FOR AMZ352-354 UNTIL 1 AM. ITS UNCLEAR HOW MUCH VSBYS WILL IMPROVE AS RAIN FILLS IN...SO ONLY TOOK THE ADVISORY UNTIL 1 AM. ADJUSTMENTS WILL BE NEEDED OVER THE NEXT FEW HRS. ADJUSTED WINDS OVER THE SOUTH CAROLINA WATERS TO NORTH OVERNIGHT AS RAP GUIDANCE SUGGESTS THE WEDGE FRONT WILL DROP SOUTH. ALSO NUDGED THE START TIME FOR THE SMALL CRAFT ADVISORY TO THE CURRENT TIME OVER THE GEORGIA OFFSHORE WATERS. SATURDAY THROUGH TUESDAY...SMALL CRAFT ADVISORY CONDITIONS WILL PERSIST OVER OUTER GEORGIA WATERS THROUGH 5 PM SATURDAY AS A WEDGE OF HIGH PRESSURE INLAND MAINTAINS AN ENHANCED PRESSURE GRADIENT OVER THESE WATERS THROUGH MUCH OF THE DAY AND SEAS REMAIN ELEVATED. THE WEDGE WILL THEN BREAK DOWN LATE AS A SFC LOW TRACKS THROUGH THE SOUTHEASTERN UNITED STATES AND INTO THE MID ATLANTIC. EXPECT SOUTHERLY WINDS TO BECOME WEST AS A TRAILING COLD FRONT SHIFTS THROUGH THE WATERS INTO EARLY SUNDAY. CONDITIONS WILL THEN REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR ALL WATERS THROUGH EARLY MONDAY AS HIGH PRESSURE DOMINANTS THE PATTERN. WINDS AND SEAS WILL THEN INCREASE MONDAY AFTERNOON INTO TUESDAY AS A WARM FRONT LIFTS NORTH AND THEN IS FOLLOWED BY A SFC LOW TRACKING OVER THE WATERS LATE. WE COULD SEE SMALL CRAFT ADVISORY CONDITIONS AS THE PRESSURE GRADIENT BECOMES ENHANCED OVER THE WATERS DURING THIS TIME. && .HYDROLOGY... STORM TOTAL RAINFALL AMOUNTS OF 3-6 INCHES WITH LOCALLY HIGHER AMOUNTS ARE LIKELY TO OCCUR ACROSS THE REGION THROUGH EARLY NEXT WEEK BRINGING MORE RELIEF TO DROUGHT STRICKEN AREAS. THESE RAINS FALLING INTO ALREADY SWOLLEN RIVERS WILL YIELD ADDITIONAL RISES AND RIVERINE FLOODING THROUGH THE END OF NEXT WEEK. ADDITIONAL RIVER FLOOD WARNINGS ARE LIKELY PER THE LATEST SHORT TERM ENSEMBLE HYDROLOGIC FORECASTS AND RIVER GUIDANCE FROM THE SOUTHEAST RIVER FORECAST CENTER. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...DENSE FOG ADVISORY UNTIL 10 PM EST THIS EVENING FOR GAZ087-088- 099-100-117>119. SC...NONE. MARINE...DENSE FOG ADVISORY UNTIL 1 AM EST SATURDAY FOR AMZ352-354. SMALL CRAFT ADVISORY UNTIL 5 PM EST SATURDAY FOR AMZ374. && $$ ST/BDC
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
723 PM EST FRI FEB 22 2013 ...DENSE FOG ADVISORY ISSUED FOR SOME AREAS THROUGH 10 PM... .SYNOPSIS... A WARM FRONT IS EXPECTED TO LIFT NORTHWARD INTO SOUTHEAST GEORGIA THROUGH TONIGHT AS A WEDGE OF HIGH PRESSURE ANCHORS OVER THE CAROLINAS. A WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE FRONT ON SATURDAY THEN PUSH NORTHEAST. HIGH PRESSURE WILL BRIEFLY RETURN TO THE AREA ON SUNDAY BEFORE A WARM FRONT LIFTS NORTH ACROSS THE AREA LATE MONDAY AND MONDAY NIGHT....FOLLOWED BY THE PASSAGE OF A COLD FRONT EARLY TUESDAY. DRIER CONDITIONS ARE EXPECTED TO RETURN TO THE REGION BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AT 22/23Z...THE WEDGE FRONT EXTENDING ROUGHLY ALONG A GEORGETOWN- WEST ASHLEY-BEAUFORT-SAVANNAH-JESUP LINE. NORTH OF THE FRONT... TEMPERATURES DROP OFF RAPIDLY INTO THE LOWER 40S TO MID 50S WHILE FARTHER SOUTH TEMPERATURES WERE IN THE UPPER 50S TO AROUND 70. THE FRONT WILL MEANDER ALONG THE COAST FOR MUCH OF THE NIGHT BEFORE BUCKLING NORTH SLIGHTLY AS A WAVE OF LOW PRESSURE DEVELOPS ALONG IT. THE PRIMARY FORECAST CONCERNS THROUGH SUNRISE CENTER ON TEMPERATURES AS WELL AS THE POTENTIAL FOR HEAVY RAIN AND DENSE FOG. HEAVY RAIN...WATER VAPOR IMAGERY SHOWS A SHORTWAVE OVER FAR SOUTHEAST ALABAMA AND THE WESTERN FLORIDA PANHANDLE MOVING NORTHEAST. UPPER FORCING IS SLOWLY INCREASING AHEAD OF THIS FEATURE AS THE UPPER LEVEL FLOW BECOMES INCREASING MORE DIFLUENT ACROSS THE SOUTHEAST U.S. IN RESPONSE TO THE DIGGING LONG-WAVE TROUGH NOTED OVER THE CENTRAL/SOUTHERN PLAINS. CLOUD TOPS ARE SLOWLY COOLING OVER SOUTHERN GEORGIA AND NORTHERN FLORIDA IN RESPONSE WITH THE COVERAGE OF RAIN STEADILY EXPANDING/INTENSIFYING TO THE SOUTHWEST PER KVAX/KTLH RADAR COMPOSITES. RAIN IS EXPECTED TO OVERSPREAD MUCH OF THE FORECAST AREA OVER THE NEXT SEVERAL HOURS AS THE SHORTWAVE APPROACHING SOUTHERN GEORGIA DRAWS CLOSER. PWATS IN EXCESS OF 1.5 INCHES /NEAR THE 99TH PERCENTILE FOR LATE FEBRUARY/ WILL SUPPORT MODERATE TO OCCASIONALLY HEAVY RAIN AT TIMES...BUT DO ANTICIPATE ANY WIDESPREAD PROBLEMS WITH FLASH FLOODING. THE LATEST RUNS OF THE HIGHER RESOLUTION SHORT TERM MODELS INCLUDING THE RAP AND H3R ARE IN GOOD AGREEMENT IN SHOWING THE WEDGE FRONT MEANDERING VERY CLOSE TO THE COAST FOR A GOOD PORTION OF THE NIGHT AND ARE NOW FOCUSING THE AXIS OF HEAVIEST RAINS OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA THROUGH SUNRISE. WILL ADJUST FIRST PERIOD POPS TO NEAR 100 PERCENT FOR ALL AREAS...INCREASE QPF SLIGHTLY AND INCLUDE A RAIN HEAVY AT TIMES QUALIFIER. THE RISK FOR TSTMS AT THIS POINT LOOKS LOW...ALTHOUGH A RUMBLE OR TWO CAN NOT BE COMPLETELY RULED OUT. TEMPERATURES...PINNING DOWN TEMPERATURES IS PROVING TO BE NEAR IMPOSSIBLE. THE LATEST RAP SUGGESTS THE WEDGE FRONT WILL DRIFT SLIGHTLY EAST OVER THE NEXT FEW HOURS...POSSIBLY EMERGING OFF THE LOWER SOUTH CAROLINA COAST. WINDS HAVE RECENTLY TURNED NORTH AT THE CHARLESTON AIRPORT WHICH AGREES WELL WITH THE RAP WIND FIELDS. HAVE ADJUSTED HOURLY TEMPERATURES TO BETTER MATCH THE REPOSITIONING OF THE WEDGE FRONT THROUGH SUNRISE. ALSO LOWERED LOW TEMPERATURES DOWN QUITE A BIT IN SOME AREAS AS SOME LOCALES WELL INLAND WERE ALREADY BELOW FORECASTED MINIMUMS. COULD VERY WELL SEE A HUGE SWING IN TEMPERATURES...ESPECIALLY AT THE COAST... SHOULD THE WARM FRONT PUSHING BACK INLAND QUICKER THAN EXPECTED. LOWS WILL RANGE FROM THE LOWER 40S WELL INLAND TO AROUND 60 IN THE LUDOWICI- DARIEN-HINESVILLE CORRIDOR...BUT THIS IS A HIGHLY UNCERTAIN FORECAST. DENSE FOG...REPORTS FROM COUNTY WARNING POINTS AND THE SAVANNAH MEDIA INDICATE DENSE FOG IS BECOMING QUITE WIDESPREAD ACROSS FAR INTERIOR SOUTHEAST GEORGIA NORTH OF THE WEDGE FRONT. VISIBILITIES WERE BEING REPORTED TO JUST A FEW FEET IN SOME LOCATIONS. HAVE HOISTED A DENSE FOG ADVISORY UNTIL 10 PM FOR CANDLER...SCREVEN... JENKINS AND BULLOCH. EXPECT CONDITIONS TO IMPROVE AS RAIN INCREASES FROM THE SOUTHWEST. AN ADVISORY HAS ALSO BEEN POSTED FOR INLAND CHATHAM...COASTAL CHATHAM AND COASTAL BRYAN WHERE SEA FOG CONTINUES TO PUSH INLAND. SIMILARLY...EXPECT CONDITIONS TO IMPROVE THERE ONCE RAIN MOVES IN BY 10 PM. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SATURDAY AND SATURDAY NIGHT...A VERY LOW CONFIDENCE FORECAST TO START THE WEEKEND. A WEDGE FRONT WILL LIKELY BE POSITIONED SOMEWHERE ACROSS NORTHWEST PORTIONS OF THE FORECAST AREA AT THE START OF THE DAY AS A WAVE OF LOW PRESSURE DEVELOPS IN THE VICINITY OF CENTRAL GEORGIA. THE LOW WILL TRACK ALONG THE WEDGE FRONT THROUGH THE DAY AND SHIFT NORTHEAST OF THE AREA IN THE EVENING AS A TRAILING COLD FRONT SWINGS THROUGH FROM THE NORTHWEST. SHOWERS ARE EXPECTED TO BE ONGOING IN THE MORNING ACROSS NORTHWEST PORTIONS OF THE AREA...WITH THE GREATEST COVERAGE TOWARD THE MIDLANDS AND EAST-CENTRAL GEORGIA...AS A DISTURBANCE APPROACHES ALOFT AND ISENTROPIC LIFT STRENGTHENS. SOME SHOWERS SHOULD ALSO BE STREAMING INTO COASTAL SOUTH CAROLINA FROM THE ADJACENT COASTAL WATERS. THE BAND OF SHOWERS OVER THE MIDLANDS AND EAST-CENTRAL GEORGIA SHOULD SHIFT SOUTHEAST OVER THE AREA DURING THE AFTERNOON AND EARLY EVENING AS THE WAVE OF LOW PRESSURE PASSES...EVENTUALLY TAPERING OFF OVERNIGHT AS THE TRAILING COLD FRONT PUSHES OFFSHORE. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES...OR NEARLY 2 STANDARD DEVIATIONS ABOVE NORMAL...THE RAIN COULD BE HEAVY AT TIMES. THERE IS A POTENTIAL FOR SOME ISOLATED THUNDERSTORMS MAINLY IN THE AFTERNOON IN THE WARM SECTOR...WHICH SHOULD BE OVER PARTS OF SOUTHEAST GEORGIA AND COASTAL SOUTHEAST SOUTH CAROLINA. TEMPERATURES WILL BE VERY DIFFICULT TO FORECAST...WITH A VERY LARGE GRADIENT EXPECTED OVER THE AREA. WITH THE WEDGE EXPECTED TO PERSIST ACROSS FAR NORTHWEST PORTIONS OF THE AREA HIGHS THERE ARE ONLY FORECAST TO BE IN THE LOWER 50S...BUT WITHIN THE WARM SECTOR HIGHS COULD BE IN THE LOWER TO MID 70S ACROSS NORTH COASTAL GEORGIA AND AREAS CLOSER TO THE ALTAMAHA. PINNING DOWN THE EXACT POSITION OF THE WEDGE IS SO DIFFICULT THAT TEMPERATURES IN SOME AREAS COULD BE OFF BY AS MUCH AS 10 DEGREES FROM THE CURRENT FORECAST. SUNDAY...HIGH PRESSURE WILL BRIEFLY BUILD OVER THE REGION FROM THE NORTHWEST WITH RAIN-FREE CONDITIONS EXPECTED. TEMPERATURES COULD REACH HIGHS AROUND 70 WITH A DOWNSLOPE WIND COMPONENT ALOFT UNDER MOSTLY SUNNY TO PARTLY CLOUDY SKIES. SUNDAY NIGHT AND MONDAY...A WARM FRONT EXTENDING FROM A STORM SYSTEM OVER THE MID-MISSISSIPPI VALLEY WILL SLOWLY LIFT NORTHWARD TOWARD THE AREA. IT APPEARS THE WARM FRONT COULD ENTER PARTS OF SOUTHEAST GEORGIA LATE IN THE DAY ON MONDAY. STRENGTHENING ISENTROPIC ASCENT AND DEEP MOISTURE AHEAD OF THE WARM FRONT SHOULD ALLOW SCATTERED TO NUMEROUS SHOWERS TO DEVELOP FROM THE SOUTH SUNDAY NIGHT...THEN BECOME NUMEROUS TO WIDESPREAD ACROSS THE AREA ON MONDAY. SOME ISOLATED THUNDERSTORMS COULD ALSO DEVELOP ACROSS SOUTHERN AREAS LATER IN THE DAY DEPENDING ON THE TIMING OF THE FRONT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... WET CONDITIONS WILL PERSIST OVER THE FORECAST AREA THROUGH EARLY NEXT WEEK AS A SFC LOW SHIFTS ACROSS THE SOUTHEAST. CONDITIONS WILL THEN BEGIN TO DRY AS THE SFC LOW SHIFTS OFF THE MID ATLANTIC COAST AND IS FOLLOWED BY HIGH PRESSURE OVER THE SOUTHEAST. A COOL AND DRY TREND SHOULD THEN TAKE PLACE THROUGH MUCH OF NEXT WEEK AS A MID/UPPER LVL LOW BECOMES CUT OFF OVER THE NORTHEASTERN UNITED STATE. OVERALL...AFTERNOON HIGHS WILL RANGE FROM THE MID 60S ON TUESDAY TO THE UPPER 50S BY THURSDAY. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 30S/LOWER 40S ON TUESDAY TO MID 30S/LOWER 40S BY THURSDAY. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... BOTH TERMINALS WILL BE IFR OR LOWER FOR MOST OF THE NIGHT AS MORE DEEP MOISTURE CONTINUES ITS TRACK UP THE COAST. DEGRADED VISIBILITIES DUE TO FOG AND RAIN ARE ALSO A POSSIBILITY AS THE WARM FRONT AND MINOR SHORTWAVE IMPULSES MOVE UP INTO THE AREA. CONDITIONS LOOK TO SLIGHTLY IMPROVE BY DAYBREAK AS THE WARM FRONT LIFTS NORTH OF KSAV AND WIND SPEEDS PICK UP...HOWEVER...MODEL SOUNDINGS ARE KEEPING THE DEEP MOISTURE IN PLACE FOR THE DAY. EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS WILL LIKELY CONTINUE THROUGH SATURDAY NIGHT DUE TO LOW CEILINGS AND REDUCED VISIBILITIES. VFR CONDITIONS WILL PREVAIL SUNDAY...THEN MVFR OR LOWER CONDITIONS SHOULD RETURN SUNDAY NIGHT THROUGH MONDAY NIGHT. VFR CONDITIONS WILL THEN PREVAIL TUESDAY INTO WEDNESDAY. && .MARINE... WATCHING FOR A POSSIBLE MARINE DENSE FOG ADVISORY FOR AT LEAST THE GEORGIA NEARSHORE WATERS. REPORTS OUT OF TYBEE ISLAND INDICATE THE SEA FOG IS GETTING PRETTY BAD OVER THE SAVANNAH RIVER ENTRANCE. ISSUED A MARINE WEATHER STATEMENT TO ADDRESS THIS SITUATION. ADJUSTED WINDS OVER THE SOUTH CAROLINA WATERS TO NORTH OVERNIGHT AS RAP GUIDANCE SUGGESTS THE WEDGE FRONT WILL DROP SOUTH. ALSO NUDGED THE START TIME FOR THE SMALL CRAFT ADVISORY TO THE CURRENT TIME OVER THE GEORGIA OFFSHORE WATERS. SATURDAY THROUGH TUESDAY...SMALL CRAFT ADVISORY CONDITIONS WILL PERSIST OVER OUTER GEORGIA WATERS THROUGH 5 PM SATURDAY AS A WEDGE OF HIGH PRESSURE INLAND MAINTAINS AN ENHANCED PRESSURE GRADIENT OVER THESE WATERS THROUGH MUCH OF THE DAY AND SEAS REMAIN ELEVATED. THE WEDGE WILL THEN BREAK DOWN LATE AS A SFC LOW TRACKS THROUGH THE SOUTHEASTERN UNITED STATES AND INTO THE MID ATLANTIC. EXPECT SOUTHERLY WINDS TO BECOME WEST AS A TRAILING COLD FRONT SHIFTS THROUGH THE WATERS INTO EARLY SUNDAY. CONDITIONS WILL THEN REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR ALL WATERS THROUGH EARLY MONDAY AS HIGH PRESSURE DOMINANTS THE PATTERN. WINDS AND SEAS WILL THEN INCREASE MONDAY AFTERNOON INTO TUESDAY AS A WARM FRONT LIFTS NORTH AND THEN IS FOLLOWED BY A SFC LOW TRACKING OVER THE WATERS LATE. WE COULD SEE SMALL CRAFT ADVISORY CONDITIONS AS THE PRESSURE GRADIENT BECOMES ENHANCED OVER THE WATERS DURING THIS TIME. && .HYDROLOGY... STORM TOTAL RAINFALL AMOUNTS OF 3-6 INCHES WITH LOCALLY HIGHER AMOUNTS ARE LIKELY TO OCCUR ACROSS THE REGION THROUGH EARLY NEXT WEEK BRINGING MORE RELIEF TO DROUGHT STRICKEN AREAS. THESE RAINS FALLING INTO ALREADY SWOLLEN RIVERS WILL YIELD ADDITIONAL RISES AND RIVERINE FLOODING THROUGH THE END OF NEXT WEEK. ADDITIONAL RIVER FLOOD WARNINGS ARE LIKELY PER THE LATEST SHORT TERM ENSEMBLE HYDROLOGIC FORECASTS AND RIVER GUIDANCE FROM THE SOUTHEAST RIVER FORECAST CENTER. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...DENSE FOG ADVISORY UNTIL 10 PM EST THIS EVENING FOR GAZ087-088- 099-100-117>119. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST SATURDAY FOR AMZ374. && $$ ST/BDC
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
651 PM EST FRI FEB 22 2013 .SYNOPSIS... A WARM FRONT IS EXPECTED TO LIFT NORTHWARD INTO SOUTHEAST GEORGIA THROUGH TONIGHT AS A WEDGE OF HIGH PRESSURE ANCHORS OVER THE CAROLINAS. A WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE FRONT ON SATURDAY THEN PUSH NORTHEAST. HIGH PRESSURE WILL BRIEFLY RETURN TO THE AREA ON SUNDAY BEFORE A WARM FRONT LIFTS NORTH ACROSS THE AREA LATE MONDAY AND MONDAY NIGHT....FOLLOWED BY THE PASSAGE OF A COLD FRONT EARLY TUESDAY. DRIER CONDITIONS ARE EXPECTED TO RETURN TO THE REGION BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AT 22/23Z...THE WEDGE FRONT EXTENDING ROUGHLY ALONG A GEORGETOWN- WEST ASHLEY-BEAUFORT-SAVANNAH-JESUP LINE. NORTH OF THE FRONT... TEMPERATURES DROP OFF RAPIDLY INTO THE LOWER 40S TO MID 50S WHILE FARTHER SOUTH TEMPERATURES WERE IN THE UPPER 50S TO AROUND 70. THE FRONT WILL MEANDER ALONG THE COAST FOR MUCH OF THE NIGHT BEFORE BUCKLING NORTH SLIGHTLY AS A WAVE OF LOW PRESSURE DEVELOPS ALONG IT. THE PRIMARY FORECAST CONCERNS THROUGH SUNRISE CENTER ON TEMPERATURES AS WELL AS THE POTENTIAL FOR HEAVY RAIN AND DENSE FOG. HEAVY RAIN...WATER VAPOR IMAGERY SHOWS A SHORTWAVE OVER FAR SOUTHEAST ALABAMA AND THE WESTERN FLORIDA PANHANDLE MOVING NORTHEAST. UPPER FORCING IS SLOWLY INCREASING AHEAD OF THIS FEATURE AS THE UPPER LEVEL FLOW BECOMES INCREASING MORE DIFLUENT ACROSS THE SOUTHEAST U.S. IN RESPONSE TO THE DIGGING LONG-WAVE TROUGH NOTED OVER THE CENTRAL/SOUTHERN PLAINS. CLOUD TOPS ARE SLOWLY COOLING OVER SOUTHERN GEORGIA AND NORTHERN FLORIDA IN RESPONSE WITH THE COVERAGE OF RAIN STEADILY EXPANDING/INTENSIFYING TO THE SOUTHWEST PER KVAX/KTLH RADAR COMPOSITES. RAIN IS EXPECTED TO OVERSPREAD MUCH OF THE FORECAST AREA OVER THE NEXT SEVERAL HOURS AS THE SHORTWAVE APPROACHING SOUTHERN GEORGIA DRAWS CLOSER. PWATS IN EXCESS OF 1.5 INCHES /NEAR THE 99TH PERCENTILE FOR LATE FEBRUARY/ WILL SUPPORT MODERATE TO OCCASIONALLY HEAVY RAIN AT TIMES...BUT DO ANTICIPATE ANY WIDESPREAD PROBLEMS WITH FLASH FLOODING. THE LATEST RUNS OF THE HIGHER RESOLUTION SHORT TERM MODELS INCLUDING THE RAP AND H3R ARE IN GOOD AGREEMENT IN SHOWING THE WEDGE FRONT MEANDERING VERY CLOSE TO THE COAST FOR A GOOD PORTION OF THE NIGHT AND ARE NOW FOCUSING THE AXIS OF HEAVIEST RAINS OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA THROUGH SUNRISE. WILL ADJUST FIRST PERIOD POPS TO NEAR 100 PERCENT FOR ALL AREAS...INCREASE QPF SLIGHTLY AND INCLUDE A RAIN HEAVY AT TIMES QUALIFIER. THE RISK FOR TSTMS AT THIS POINT LOOKS LOW...ALTHOUGH A RUMBLE OR TWO CAN NOT BE COMPLETELY RULED OUT. TEMPERATURES...PINNING DOWN TEMPERATURES IS PROVING TO BE NEAR IMPOSSIBLE. THE LATEST RAP SUGGESTS THE WEDGE FRONT WILL DRIFT SLIGHTLY EAST OVER THE NEXT FEW HOURS...POSSIBLY EMERGING OFF THE LOWER SOUTH CAROLINA COAST. WINDS HAVE RECENTLY TURNED NORTH AT THE CHARLESTON AIRPORT WHICH AGREES WELL WITH THE RAP WIND FIELDS. HAVE ADJUSTED HOURLY TEMPERATURES TO BETTER MATCH THE REPOSITIONING OF THE WEDGE FRONT THROUGH SUNRISE. ALSO LOWERED LOW TEMPERATURES DOWN QUITE A BIT IN SOME AREAS AS SOME LOCALES WELL INLAND WERE ALREADY BELOW FORECASTED MINIMUMS. COULD VERY WELL SEE A HUGE SWING IN TEMPERATURES...ESPECIALLY AT THE COAST... SHOULD THE WARM FRONT PUSHING BACK INLAND QUICKER THAN EXPECTED. LOWS WILL RANGE FROM THE LOWER 40S WELL INLAND TO AROUND 60 IN THE LUDOWICI- DARIEN-HINESVILLE CORRIDOR...BUT THIS IS A HIGHLY UNCERTAIN FORECAST. FOG...SURFACE OBSERVATIONS AND MEDIA REPORTS SUGGEST THE FOG IS BECOMING RATHER DENSE NORTH OF THE WARM FRONT...ESPECIALLY IN INTERIOR SOUTHEAST GEORGIA. WILL HOLD OFF ON A DENSE FOG ADVISORY FOR THIS AREA AS SOME IMPROVEMENT IS EXPECTED TO OCCUR AS RAIN FILLS IN OVER THE NEXT 1-2 HOURS. HOWEVER...THIS WILL BE WATCHED CAREFULLY. ALSO...DENSE SEA FOG IS BEGINNING TO PUSH INLAND ALONG PORTIONS OF NORTH COASTAL GEORGIA WHERE DEWPOINTS ARE SURGING TO AS MUCH AS 10 DEGREES ABOVE THE CHILLY SHELF WATERS. AGAIN...WILL HOLD OFF ON HOISTING AN ADVISORY FOR NOW...BUT THIS MAY NEED TO BE REEVALUATED WITHIN THE HOUR IF CONDITIONS DO NOT IMPROVE. SPECIAL WEATHER STATEMENTS HAVE BEEN ISSUE TO ADDRESS BOTH AREAS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SATURDAY AND SATURDAY NIGHT...A VERY LOW CONFIDENCE FORECAST TO START THE WEEKEND. A WEDGE FRONT WILL LIKELY BE POSITIONED SOMEWHERE ACROSS NORTHWEST PORTIONS OF THE FORECAST AREA AT THE START OF THE DAY AS A WAVE OF LOW PRESSURE DEVELOPS IN THE VICINITY OF CENTRAL GEORGIA. THE LOW WILL TRACK ALONG THE WEDGE FRONT THROUGH THE DAY AND SHIFT NORTHEAST OF THE AREA IN THE EVENING AS A TRAILING COLD FRONT SWINGS THROUGH FROM THE NORTHWEST. SHOWERS ARE EXPECTED TO BE ONGOING IN THE MORNING ACROSS NORTHWEST PORTIONS OF THE AREA...WITH THE GREATEST COVERAGE TOWARD THE MIDLANDS AND EAST-CENTRAL GEORGIA...AS A DISTURBANCE APPROACHES ALOFT AND ISENTROPIC LIFT STRENGTHENS. SOME SHOWERS SHOULD ALSO BE STREAMING INTO COASTAL SOUTH CAROLINA FROM THE ADJACENT COASTAL WATERS. THE BAND OF SHOWERS OVER THE MIDLANDS AND EAST-CENTRAL GEORGIA SHOULD SHIFT SOUTHEAST OVER THE AREA DURING THE AFTERNOON AND EARLY EVENING AS THE WAVE OF LOW PRESSURE PASSES...EVENTUALLY TAPERING OFF OVERNIGHT AS THE TRAILING COLD FRONT PUSHES OFFSHORE. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES...OR NEARLY 2 STANDARD DEVIATIONS ABOVE NORMAL...THE RAIN COULD BE HEAVY AT TIMES. THERE IS A POTENTIAL FOR SOME ISOLATED THUNDERSTORMS MAINLY IN THE AFTERNOON IN THE WARM SECTOR...WHICH SHOULD BE OVER PARTS OF SOUTHEAST GEORGIA AND COASTAL SOUTHEAST SOUTH CAROLINA. TEMPERATURES WILL BE VERY DIFFICULT TO FORECAST...WITH A VERY LARGE GRADIENT EXPECTED OVER THE AREA. WITH THE WEDGE EXPECTED TO PERSIST ACROSS FAR NORTHWEST PORTIONS OF THE AREA HIGHS THERE ARE ONLY FORECAST TO BE IN THE LOWER 50S...BUT WITHIN THE WARM SECTOR HIGHS COULD BE IN THE LOWER TO MID 70S ACROSS NORTH COASTAL GEORGIA AND AREAS CLOSER TO THE ALTAMAHA. PINNING DOWN THE EXACT POSITION OF THE WEDGE IS SO DIFFICULT THAT TEMPERATURES IN SOME AREAS COULD BE OFF BY AS MUCH AS 10 DEGREES FROM THE CURRENT FORECAST. SUNDAY...HIGH PRESSURE WILL BRIEFLY BUILD OVER THE REGION FROM THE NORTHWEST WITH RAIN-FREE CONDITIONS EXPECTED. TEMPERATURES COULD REACH HIGHS AROUND 70 WITH A DOWNSLOPE WIND COMPONENT ALOFT UNDER MOSTLY SUNNY TO PARTLY CLOUDY SKIES. SUNDAY NIGHT AND MONDAY...A WARM FRONT EXTENDING FROM A STORM SYSTEM OVER THE MID-MISSISSIPPI VALLEY WILL SLOWLY LIFT NORTHWARD TOWARD THE AREA. IT APPEARS THE WARM FRONT COULD ENTER PARTS OF SOUTHEAST GEORGIA LATE IN THE DAY ON MONDAY. STRENGTHENING ISENTROPIC ASCENT AND DEEP MOISTURE AHEAD OF THE WARM FRONT SHOULD ALLOW SCATTERED TO NUMEROUS SHOWERS TO DEVELOP FROM THE SOUTH SUNDAY NIGHT...THEN BECOME NUMEROUS TO WIDESPREAD ACROSS THE AREA ON MONDAY. SOME ISOLATED THUNDERSTORMS COULD ALSO DEVELOP ACROSS SOUTHERN AREAS LATER IN THE DAY DEPENDING ON THE TIMING OF THE FRONT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... WET CONDITIONS WILL PERSIST OVER THE FORECAST AREA THROUGH EARLY NEXT WEEK AS A SFC LOW SHIFTS ACROSS THE SOUTHEAST. CONDITIONS WILL THEN BEGIN TO DRY AS THE SFC LOW SHIFTS OFF THE MID ATLANTIC COAST AND IS FOLLOWED BY HIGH PRESSURE OVER THE SOUTHEAST. A COOL AND DRY TREND SHOULD THEN TAKE PLACE THROUGH MUCH OF NEXT WEEK AS A MID/UPPER LVL LOW BECOMES CUT OFF OVER THE NORTHEASTERN UNITED STATE. OVERALL...AFTERNOON HIGHS WILL RANGE FROM THE MID 60S ON TUESDAY TO THE UPPER 50S BY THURSDAY. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 30S/LOWER 40S ON TUESDAY TO MID 30S/LOWER 40S BY THURSDAY. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... BOTH TERMINALS WILL BE IFR OR LOWER FOR MOST OF THE NIGHT AS MORE DEEP MOISTURE CONTINUES ITS TRACK UP THE COAST. DEGRADED VISIBILITIES DUE TO FOG AND RAIN ARE ALSO A POSSIBILITY AS THE WARM FRONT AND MINOR SHORTWAVE IMPULSES MOVE UP INTO THE AREA. CONDITIONS LOOK TO SLIGHTLY IMPROVE BY DAYBREAK AS THE WARM FRONT LIFTS NORTH OF KSAV AND WIND SPEEDS PICK UP...HOWEVER...MODEL SOUNDINGS ARE KEEPING THE DEEP MOISTURE IN PLACE FOR THE DAY. EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS WILL LIKELY CONTINUE THROUGH SATURDAY NIGHT DUE TO LOW CEILINGS AND REDUCED VISIBILITIES. VFR CONDITIONS WILL PREVAIL SUNDAY...THEN MVFR OR LOWER CONDITIONS SHOULD RETURN SUNDAY NIGHT THROUGH MONDAY NIGHT. VFR CONDITIONS WILL THEN PREVAIL TUESDAY INTO WEDNESDAY. && .MARINE... WATCHING FOR A POSSIBLE MARINE DENSE FOG ADVISORY FOR AT LEAST THE GEORGIA NEARSHORE WATERS. REPORTS OUT OF TYBEE ISLAND INDICATE THE SEA FOG IS GETTING PRETTY BAD OVER THE SAVANNAH RIVER ENTRANCE. ISSUED A MARINE WEATHER STATEMENT TO ADDRESS THIS SITUATION. ADJUSTED WINDS OVER THE SOUTH CAROLINA WATERS TO NORTH OVERNIGHT AS RAP GUIDANCE SUGGESTS THE WEDGE FRONT WILL DROP SOUTH. ALSO NUDGED THE START TIME FOR THE SMALL CRAFT ADVISORY TO THE CURRENT TIME OVER THE GEORGIA OFFSHORE WATERS. SATURDAY THROUGH TUESDAY...SMALL CRAFT ADVISORY CONDITIONS WILL PERSIST OVER OUTER GEORGIA WATERS THROUGH 5 PM SATURDAY AS A WEDGE OF HIGH PRESSURE INLAND MAINTAINS AN ENHANCED PRESSURE GRADIENT OVER THESE WATERS THROUGH MUCH OF THE DAY AND SEAS REMAIN ELEVATED. THE WEDGE WILL THEN BREAK DOWN LATE AS A SFC LOW TRACKS THROUGH THE SOUTHEASTERN UNITED STATES AND INTO THE MID ATLANTIC. EXPECT SOUTHERLY WINDS TO BECOME WEST AS A TRAILING COLD FRONT SHIFTS THROUGH THE WATERS INTO EARLY SUNDAY. CONDITIONS WILL THEN REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR ALL WATERS THROUGH EARLY MONDAY AS HIGH PRESSURE DOMINANTS THE PATTERN. WINDS AND SEAS WILL THEN INCREASE MONDAY AFTERNOON INTO TUESDAY AS A WARM FRONT LIFTS NORTH AND THEN IS FOLLOWED BY A SFC LOW TRACKING OVER THE WATERS LATE. WE COULD SEE SMALL CRAFT ADVISORY CONDITIONS AS THE PRESSURE GRADIENT BECOMES ENHANCED OVER THE WATERS DURING THIS TIME. && .HYDROLOGY... STORM TOTAL RAINFALL AMOUNTS OF 3-6 INCHES WITH LOCALLY HIGHER AMOUNTS ARE LIKELY TO OCCUR ACROSS THE REGION THROUGH EARLY NEXT WEEK BRINGING MORE RELIEF TO DROUGHT STRICKEN AREAS. THESE RAINS FALLING INTO ALREADY SWOLLEN RIVERS WILL YIELD ADDITIONAL RISES AND RIVERINE FLOODING THROUGH THE END OF NEXT WEEK. ADDITIONAL RIVER FLOOD WARNINGS ARE LIKELY PER THE LATEST SHORT TERM ENSEMBLE HYDROLOGIC FORECASTS AND RIVER GUIDANCE FROM THE SOUTHEAST RIVER FORECAST CENTER. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST SATURDAY FOR AMZ374. && $$ ST/BDC
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
610 PM CST FRI FEB 22 2013 .SYNOPSIS... ISSUED AT 257 PM CST FRI FEB 22 2013 SLOWLY FILLING SURFACE LOW THAT HAS MOVED NORTH ACROSS THE FORECAST AREA TODAY IS CONTINUING TO MOVE UP INTO SOUTHERN WISCONSIN...AND AS OF 2 PM WAS LOCATED WEST OF MADISON WISCONSIN...WITH A BROAD AREA OF PRESSURE FALLS OVER WISCONSIN. A VERY WEAK TROUGH AXIS EXTENDS BACK INTO NORTHERN IOWA...WHERE SNOW CONTINUES TO FALL VERY LIGHTLY. LOW CLOUDS EXTEND BACK INTO NORTHERN MISSOURI. THERE IS AN AREA IN NORTHWEST MISSOURI WHERE THE CLOUDS HAVE EITHER THINNED OR CLEARED OUT ENTIRELY AS WE CAN SEE THE TEXTURE OF THE GROUND BENEATH ON VISIBLE SATELLITE IMAGERY. THIS IS IN A OBSERVATIONAL DATA VOID AREA...SO IT IS HARD TO DETERMINE WHAT EXACTLY IS GOING ON. AT UPPER LEVELS...BROAD UPPER LEVEL TROUGH OVER THE WESTERN CONUS WITH THE STRONG SHORTWAVE OVER THE MIDWEST ASSOCIATED WITH THIS STORM SYSTEM. STRONG PRESSURE FALLS AHEAD OF THE SHORTWAVE IMPLY THAT IT WILL CONTINUE NORTHEAST...BUT SMALL RISES BEHIND IT SHOW THAT IT IS FILLING AND THE BROADER SCALE TROUGH IS STILL DEEPENING. ..LE.. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 257 PM CST FRI FEB 22 2013 THIS AFTERNOON THE SNOW BAND IS EXPECTED TO CONTINUE TO MOVE NORTHEAST OUT OF THE AREA...AND PLAN ON ALLOWING THE WINTER STORM WARNING AND ADVISORY EXPIRE HERE AT 3 PM. SOME FLURRIES WILL LIKELY STILL AFFECT THE NORTHERN THIRD OF THE FORECAST AREA WITH SOME LOW LEVEL CONVERGENCE AND LIFT GOING ON ACCORDING TO THE RUC THIS EVENING. THUS...HAVE CONTINUED THE SLIGHT CHANCE POPS THIS EVENING BUT WITH NO ACCUMULATIONS EXPECTED. TONIGHT THE SURFACE LOW EJECTS OFF TO THE NORTHEAST...AND WILL BE OVER THE UP OF MICHIGAN BY 06Z TONIGHT. THAT WILL DRAW THE LIFT AND MOST OF THE MOISTURE OFF TO THE NORTHEAST...LEAVING US WITH SOME LINGERING LOW LEVEL MOISTURE. IN FACT...ACCORDING TO SOUNDINGS WE REMAIN FAIRLY WELL SATURATED BELOW 850MB THROUGH SATURDAY MORNING. FLURRIES SHOULD BE POSSIBLE AS THE LEAST LITTLE WIGGLE IS GOING TO PRODUCE THEM. IT APPEARS THAT WE WILL BE COLD ENOUGH AT THE TOP OF THAT LAYER FOR THESE TO BE FLURRIES INSTEAD OF FREEZING DRIZZLE..BUT LATER SHIFTS WILL HAVE TO WATCH FOR THIS. UPSTREAM MIN TEMPERATURES FELL INTO THE TEENS OVER NEBRASKA AND KANSAS LAST NIGHT...SO HAVE KEPT THE MIN TEMPS IN THE TEENS OVERNIGHT. MAY BE SLIGHTLY WARMER WITH THE EXTRA CLOUD COVER...SO DID NOT BRING IN ANY SINGLE DIGIT VALUES. THE EXTRA CLOUD COVER IS ALSO GOING TO KEEP TEMPS FROM FALLING OFF VERY FAST OVERNIGHT...SO A SLOW DROP OFF IN THE EVENING IS EXPECTED. SATURDAY TO BE COLD AND QUIET WITH THE STORM OFF TO THE NORTHEAST AND A GRADUAL CLEARING TREND FROM THE SOUTH. WE ARE NOT BRINGING IN A COLD AIRMASS BEHIND THIS SYSTEM...BUT WITH THE SNOW COVER WE ARE GOING TO BE COLDER THAN WE WOULD WITHOUT. SO...EXPECT HIGHS IN THE 20S TO NEAR 30. LINGERING LOW LEVEL MOISTURE SHOULD LIFT TO AFTERNOON STRATOCUMULUS...BUT STILL ALLOWING A FAIR AMOUNT OF SUNSHINE THROUGH. ..LE.. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 257 PM CST FRI FEB 22 2013 ANOTHER MAJOR AND STRONGER WINTER STORM FOR MONDAY/TUESDAY THE MAIN FORECAST CHALLENGE. OVERVIEW...INITIALIZATION GOOD TO EXCELLENT UPSTREAM INTO THE NORTH PACIFIC. THE 18Z VERIFICATION SUPPORT ALL 4 LONGER RANGE SOLUTIONS VERIFYING WELL AND ARE ALL SIMILAR. THATS THE GOOD NEWS...UNLESS ONE LIKES LOTS OF SNOW...THEY ALL PUT AREA IN THE WHEELHOUSE OF A MAJOR WINTER STORM WITH STRONG WINDS. PREFER A BLEND OF ALL 4 AS A MIX WHICH SUPPORTS MOST OR ALL THE AREA TO PICK UP ANOTHER 4-6+ INCHES OF SNOW WITH LOCALLY UP TO OVER 12 INCHES POSSIBLE WITH WINDS OF 20 TO 35+ MPH AND POSSIBLY HIGHER. THE CONSISTENCY OF FORCING OF UPPER JET STRUCTURE TOOLS ALL SUGGEST IF THIS TREND CONTINUES THE NEXT 24 HOURS THAT OUR AREA WILL SEE A MAJOR...HIGHER END WINTER STORM EVENT WITH POSSIBLE NEAR BLIZZARD CONDITIONS. WILL UPDATE THE LOCAL HWODVN HAZARDOUS WEATHER OUTLOOK PRODUCT FOR STRONGER AND HIGHER IMPACT WORDING. SATURDAY NIGHT AND SUNDAY...VERY MINOR CHANGES WITH LESS CLOUDS ARE LIKELY SUPPORTING LOWER MINS FROM OUR SNOW-PACK AND HIGHER MAX TEMP VALUES FROM LATE FEBRUARY SUNSHINE. LATER SHIFTS MAY NEED TO BUMP HIGHS A FEW MORE DEGREES DUE TO THE SUNSHINE. SUNDAY NIGHT...SEE INCREASING CLOUDS AND KEPT VERY LOW POPS FAR WEST SECTIONS OVERNIGHT AS LEADING EDGE OF ELEVATED FORCING FOR THE NEXT MAJOR WINTER STORM ARRIVES WITH MAIN BRUNT OF FORCING ON TAP TO IMPACT THE AREA LATER ON MONDAY PM HOURS INTO TUESDAY. MONDAY THROUGH NEXT WEDNESDAY...HAVE UPPED POPS MONDAY NIGHT AND TUESDAY TO LIKELY WITH MODERATE TO HEAVY SNOW AMOUNTS SUGGESTED. NUMEROUS TOOLS SUGGEST MOST OF THE AREA TO SEE WELL OVER 4+ INCHES WITH MOST RELIABLE TOOLS ALL SUGGESTING A SWATH OF 6-12+ INCHES OF HEAVY SNOW THAT RIGHT NOW IS TRENDING TOWARD A IRK-MUS-FEP LINE. THIS SHOULD BE BETTER CLARIFIED IN THE NEXT 24 HOURS. IF PHASING ON THE BACK SIDE OCCURS AS SUGGESTED BY SOME SOLUTIONS WITH STRONGER OCCLUSION THEN STRONGER COLD CONVEYOR BELT SUGGESTED AND NEAR BLIZZARD CONDITIONS LIKELY. SOME TOOLS SUGGEST WIND GUSTS OF 40-45 MPH WHICH ARE VERY CLOSE TO BLIZZARD THRESHOLD FOR LATER SHIFTS TO MONITOR. THERE IS NO DOUBT THIS WILL BE A MAJOR EVENT LAST 12-18+ HOURS AND LIKELY GREATER THAN THE EVENT THE PAST 24 HOURS. THIS IS A DEVELOPING SYSTEM THAT WILL STRENGTHEN VERSUS A WEAKENING AND FILLING SYSTEM THAT PASSED. ADD WERE IN THE NATURAL BAROCLINIC ZONE OF A PRONOUNCED SNOW AND NO SNOW LINE...THIS MAKES RISK OF A MAJOR EVENT GREATER. THE DATA AS OF NOW...SUPPORTS AT LEAST PART OF THE AREA WILL SEE A MAJOR WINTER STORM. AREA SNOW TO LIQUID WATER EQUIVALENT RATIOS ARE SUGGESTED TO BE IN THE 12-15 TO 1 RANGE. ARE TEMPERATURES SHOULD STAY IN THE MID 20S TO LOWER 30S FOR THIS EVENT. THURSDAY AND FRIDAY...DRY WITH BELOW NORMAL TEMPERATURES AND WITH AN EVEN GREATER THICKER AND FRESH SNOW PACK LIKELY...AREA TEMPS ARE AGAIN PROBABLY TOO MILD. MINS COULD BE AT LEAST 5 TO 10 DEGREES TOO MILD FOR LATER SHIFTS TO RECONSIDER. NORTHWESTERLY FLOW AND BELOW NORMAL TEMPERATURES REMAIN APPEAR LIKELY INTO THE FIRST FEW DAYS OF MARCH...ALL INDICATIONS ARE THIS MARCH WILL NOTHING LIKE THE RECORD WARM MARCH OF 2012. NICHOLS && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 552 PM CST FRI FEB 22 2013 CYCLONIC FLOW AROUND LOW PRESSURE OVER WISCONSIN AND HIGH LOW LEVEL MOISTURE WILL KEEP CLOUDS BASED BETWEEN 2KFT AND 3KFT IN PLACE THROUGH SATURDAY MORNING. CLEARING SHOULD OCCUR FROM LATE SATURDAY MORNING INTO THE AFTERNOON AS DRIER AIR MOVES IN FROM THE WEST. A FEW SNOW SHOWERS WILL LINGER OVER AREAS NORTH OF I80 EARLY THIS EVENING WITH VISIBLITIES AS LOW AS 1 OR 2 MILES IN THE HEAVIER SHOWERS. AFTER THE SNOW SHOWERS END VSBYS SHOULD BE AOA 6SM THROUGH SATURDAY AFTERNOON. DLF && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...LE SHORT TERM...LE LONG TERM...WDN AVIATION...DLF
AREA FORECAST DISCUSSION
NWS DES MOINES IA
358 PM CST THU FEB 21 2013 .SHORT TERM /TONIGHT/... SNOW BAND ADVECTING NORTHWARD ACROSS MUCH OF THE FORECAST AREA THIS AFTERNOON INTO THE EVENING CAUSING RAPIDLY DETERIORATING CONDITIONS. MODELS REMAIN IN GREAT AGREEMENT WITH TIMING AND PLACEMENT OF HEAVIEST BAND TONIGHT AND WITH THE UPPER LOW TRACK DURING THE OVERNIGHT HOURS. LEANED TOWARD THE TIMING OF NAM12/HRRR/HIRES ARW-WRF FOR BAND DURING THE EVENING HOURS AND SREF/NAM OVERNIGHT. IMPRESSIVE ISENTROPIC LIFT AHEAD OF THE UPPER LOW...GENERALLY ALONG THE 285K TO 305K ISENTROPIC SURFACES...COMBINED WITH GOOD MOISTURE TRANSPORT WILL CONTINUE TO PUSH THE CURRENT SNOW BAND FURTHER NORTH LATE THIS AFTERNOON AND EVENING. THE ISENTROPIC LIFT DIMINISHES IN STRENGTH AS THE UPPER LOW APPROACHES FROM KANSAS LATER TONIGHT INTO THE OVERNIGHT HOURS BUT ENOUGH DEEP FORCING ASSOCIATED WITH IT AS IT PASSES THROUGH THE STATE TO KEEP HIGH POPS GOING OVERNIGHT. ALSO...EXPECTING THE SNOW TO CONTINUE TO FILL IN ACROSS SOUTHWEST IOWA AND REMAIN FAIRLY PERSISTENT ACROSS THE FORECAST AREA FOR SEVERAL HOURS TONIGHT. RAP CONFIRMS THIS AS IT HAS MAX OMEGA WITHIN THE DENDRITIC LAYER PERSISTING THROUGH 02Z AT DSM...AND THROUGH 06Z ACROSS NORTH CENTRAL IOWA. EVEN WITH SNOW INTENSITIES DIMINISHING...STILL EXPECTING LIGHTER SNOWFALL ACCUMULATIONS B/T 06Z AND 12Z FRIDAY WITH PASSAGE OF THE UPPER LOW. LEANED TOWARD A BLEND OF THE GFS/NAM FOR QPF AMOUNTS AND STILL ON TRACK FOR GOOD SWATH OF 6 TO 9 INCHES GENERALLY SOUTH OF HIGHWAY 20. SLIGHTLY LESS FURTHER NORTH AS THE BEST FORCING SKIRTS TO ITS SOUTHEAST. SHARP PRESSURE GRADIENT ACROSS THE STATE KEEPS EAST TO NORTHEAST WINDS GUSTS THROUGH 03-06Z TONIGHT BEFORE DIMINISHING. 925MB WINDS AT 03Z STILL GUSTING AT 30KTS OVER CENTRAL PORTION OF THE FORECAST AREA. VISIBILITY RAPIDLY DIMINISHING WITH THE ONSET OF THE SNOW AND WILL PERSIST BEFORE THE WINDS WEAKEN LATER THIS EVENING. .LONG TERM /FRIDAY THROUGH THURSDAY/... UPPER LOW WILL BE DEPARTING TO THE NORTHEAST ON FRIDAY WITH FORCING SUBSIDING THROUGH THE DAY. HAVE CONTINUED CATEGORICAL WORDING IN THE FAR NORTHEAST DURING THE MORNING WITH A DECENT GRADIENT TO ESSENTIALLY NO PCPN IN FAR SOUTHWEST. SUBSIDENCE WILL CONTINUE TO OVERSPREAD THE AREA DURING THE DAY AND HAVE CUT THE POPS OFF ACROSS THE SOUTH BY AFTERNOON AND LEFT SCATTERED SNOW SHOWERS AND FLURRIES IN THE NORTH UNDER THE UPPER LOW WHERE SOME WEAK LIFT WILL CONTINUE TO RESIDE. THE THREAT OF ANY PCPN WILL END BY SATURDAY NIGHT IN THE NORTH AS THE SYSTEM PULLS AWAY. THE 850MB THERMAL TROF IS NEARLY ASSOCIATED WITH THE UPPER LOW SO WARM ADVECTION WILL COMMENCE IMMEDIATELY ON FRIDAY NIGHT INTO SATURDAY ON BACKSIDE OF THE SYSTEM. THIS WILL KEEP TEMPERATURES FROM DROPPING AS MUCH AS WOULD BE EXPECTED WITH FRESH SNOW COVER WITH HIGHS ON SUNDAY APPROACHING OR SLIGHTLY ABOVE FREEZING. FOCUS WILL THEN SHIFT ON SHORTWAVE DROPPING INTO THE ROCKIES DURING THE WEEKEND. GFS IS FARTHER NORTH AND FASTER WITH THE EVOLUTION OF THIS SYSTEM AND APPEARS TO BE THE ODD MODEL OUT. THE EURO AND GEM HAVE BEEN MORE CONSISTENT DIGGING THE SYSTEM THROUGH THE INTERMOUNTAIN WEST THEN MOVING THE STORM EASTWARD THROUGH THE MID MISSISSIPPI RIVER VALLEY. THE IMPLICATIONS OF THIS WOULD BE TO KEEP THE BULK OF FORCING AND MOISTURE TO OUR SOUTH WITH MISSOURI SEEING THE WORST CONDITIONS. HOWEVER...SOME WEAKER FORCING WILL BLEED INTO THE STATE AS THE UPPER TROF IS ELONGATED FROM THE CENTRAL INTO THE NORTHERN PLAINS. THEREFORE...SOME SNOWFALL IS STILL EXPECTED ACROSS THE STATE FROM LATE SUNDAY NIGHT INTO TUESDAY MORNING...PRIMARILY IMPACTING THE SOUTHERN HALF OF IOWA. SOME LIGHT TO MODERATE ACCUMULATIONS ARE EXPECTED WITH THIS STORM AND WILL CONTINUE TO MONITOR THE TRACK SINCE ANY NORTHWARD SHIFT WOULD BEGIN TO BRING SIGNIFICANTLY HIGHER AMOUNTS INTO THE STATE. AFTER THIS SYSTEM PULLS AWAY...DRIER CONDITIONS ARE EXPECTED WITH TEMPERATURES BELOW NORMAL WITH COOL NORTHERLY FLOW BEHIND THE SYSTEM. && .AVIATION...21/18Z SNOW DEVELOPING OVER SOUTHERN IOWA WILL CONTINUE TO PUSH NORTH AND AFFECT DSM/OTM OVER THE NEXT 2-3 HOURS. HAVE MVFR CONDITIONS QUICKLY DIMINISHING TO LIFR CONDITIONS AT DSM/OTM AFTER 21Z AND WILL PERSIST THROUGH THE EARLY EVENING HOURS. TIMING FOR ALO/MCW/FOD IS LATER THIS AFTERNOON/EARLY EVENING. CONFIDENCE IS HIGH WITH RAPIDLY DETERIORATING CONDITIONS. EXPECTING A GOOD 4-6 HOUR PERIOD OF BLSN AND LIFR VIS BEFORE SNOW BECOMES LIGHTER LATER THIS EVENING. HAVE IFR/MVFR VIS/CIGS THROUGH FRIDAY MORNING. && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL NOON CST FRIDAY FOR ADAIR-ADAMS-APPANOOSE-AUDUBON-BOONE-CALHOUN-CARROLL-CASS-CLARKE- CRAWFORD-DALLAS-DAVIS-DECATUR-GREENE-GUTHRIE-JASPER-LUCAS-MADISON- MAHASKA-MARION-MONROE-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAYLOR-UNION- WAPELLO-WARREN-WAYNE-BLACK HAWK-BREMER-BUTLER-CERRO GORDO-EMMET- FRANKLIN-GRUNDY-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-KOSSUTH-MARSHALL- PALO ALTO-POCAHONTAS-TAMA-WEBSTER-WINNEBAGO-WORTH-WRIGHT. && $$ AVIATION/SHORT TERM...KLP LONG TERM...COGIL
AREA FORECAST DISCUSSION
NWS TOPEKA KS
342 PM CST THU FEB 21 2013 .DISCUSSION... TONIGHT THROUGH FRIDAY... THE UPPER LEVEL LOW WAS LOCATED ACROSS THE NORTHEAST TEXAS PANHANDLE THIS AFTERNOON. ONE 1.5PV ANOMALY WAS LIFTING NORTHWARD ACROSS WEST CENTRAL KS...WITH A SECOND 1.5PV ANOMALY OVER WESTERN OK. THE SHORT-TERM MODELS...HRRR AND RAP SHOW THE 1.5PV ANOMALY LIFTING NORTHEAST ACROSS EASTERN KS. AHEAD OF THE 1.5PV ANOMALY THE FRONTOGENETICAL FORCING SHOULD INCREASE TO PROVIDE A PERIOD OF LIGHT SNOW. THE MODELS SHOW AN INCREASE IN THE NEGATIVE SATURATED EPV...CSI...WHICH COULD CAUSE SOME SLIGHTLY HEAVIER SNOW BANDS...THUS THE WESTERN AND CENTRAL COUNTIES OF THE CWA COULD SEE SOME LOCALLY HIGHER SNOW AMOUNTS. UNTIL THE DENDRITIC GROWTH ZONE SATURATES LATER THIS AFTERNOON THERE MAY BE PERIODS OF FREEZING DRIZZLE ACROSS THE EASTERN HALF OF THE CWA. THE PATCHY FREEZING DRIZZLE MAY REFORM LATER THIS EVENING ONCE THE STRONGER ASCENT SHIFTS NORTHEAST OF THE CWA. ISENTROPIC DOWNGLIDE SHOULD BRING AN END THE THE FREEZING DRIZZLE CHANCE AFTER MIDNIGHT. THE STORM TOTAL SNOWFALL WILL RANGE FROM 6 TO 15 INCHES WITH SOME LOCALLY HIGHER AMOUNTS. I WILL KEEP THE WINTER STORM WARNING IN EFFECT UNTIL 00Z FOR THE WESTERN HALF OF THE CWA AND UNTIL MIDNIGHT FOR THE EASTERN HALF OF THE CWA. FRIDAY...THE SKIES SHOULD BEGIN TO CLEAR FROM WEST TO EAST ACROSS THE CWA THROUGH THE MID AND LATE MORNING HOURS. HIGHS WILL CONTINUE TO BE COLD WITH MID 20S...GIVEN SEVERAL INCHES OF SNOW COVER. GARGAN FRIDAY NIGHT THROUGH THURSDAY... DRY CONDITIONS ARE EXPECTED FOR THE START OF THE WEEKEND AS THE UPPER LEVEL TROUGH THAT IMPACTED THE REGION WITH WINTER WEATHER TODAY SLIDES NORTH TOWARD THE GREAT LAKES REGION. SURFACE HIGH PRESSURE BRIEFLY WILL SETTLE INTO THE REGION BEHIND THE EXITING STORM SYSTEM BEFORE THE NEXT UPPER LEVEL TROUGH BEGINS TO DIG SOUTHWARD ACROSS THE NORTHERN AND CENTRAL PLAINS DURING THE LATTER PART OF THE WEEKEND. THERE IS STILL UNCERTAINTY AMONGST THE MODELS REGARDING JUST HOW FAR SOUTH THIS TROUGH WILL DIG ALONG AND EAST OF THE ROCKY MOUNTAINS AND HOW QUICKLY THE UPPER LOW EJECTS NORTHEASTWARD ACROSS THE FORECAST AREA AND FURTHER EAST OF THE AREA. THESE MODEL DISCREPANCIES LEAD TO DIFFICULTIES IN PINNING DOWN THE TIMING OF ANY PRECIPITATION FROM THIS SYSTEM. MODELS SEEM TO BE A BIT SLOWER IN BRINGING THE SYSTEM INTO THE AREA...SO HAVE DECREASED POPS FOR SUNDAY WITH CHANCE POPS FOR THE SUNDAY NIGHT THROUGH MONDAY NIGHT TIMEFRAME. THESE POPS BEST REFLECT A BLEND OF THE ECMWF/GEM. THE GFS CURRENTLY IS AN OUTLIER IN KEEPING THE UPPER TROUGH FURTHER NORTH AND ONLY HAVING PRECIPITATION SKIMMING ACROSS THE NORTHERN PORTION OF THE FORECAST AREA. DEPENDING UPON THE TIMING OF PRECIPITATION...THE REGION COULD SEE A COMBINATION OF RAIN AND SNOW SHOWERS WITH THIS SYSTEM. AT THIS TIME...THE SYSTEM LOOKS TO EXIT EAST OF THE AREA BY TUESDAY. A WEAK RIDGE WILL MOVE INTO THE REGION BEHIND THIS TROUGH WITH DRY CONDITIONS EXPECTED FOR MID-WEEK. BY THE END OF THE PERIOD MODEL DISCREPANCIES EXIST WITH REGARDS TO THE NEXT SHORTWAVE THAT EJECTS INTO THE CENTRAL PLAINS. KEPT ANY MENTION OF PRECIPITATION OUT OF THE FORECAST AT THIS TIME. TEMPERATURE FORECASTS FOR THE PERIOD HAVE BEEN COMPLICATED BY THE SEVERAL INCHES OF SNOW RECEIVED ACROSS THE FORECAST AREA FROM TODAY`S STORM. WITH THIS IN MIND...HAVE TRENDED WITH TEMPERATURES STAYING BELOW THE SEASONAL NORMALS THROUGH THE EXTENDED FORECAST PERIOD...WITH HIGHS GENERALLY IN THE 30S. THE COLDEST NIGHT LOOKS TO BE FRIDAY NIGHT/EARLY SATURDAY MORNING AS LOW TEMPERATURES PLUMMET INTO THE SINGLE DIGITS...WITH WIND CHILL VALUES ANYWHERE FROM ZERO TO 8 BELOW ZERO. OTHERWISE...LOWS GENERALLY LOOK TO BE IN THE TEENS AND 20S. TEMPERATURE FORECASTS WILL NEED TO BE ADJUSTED DEPENDING UPON ANY MELTING OF SNOW THAT OCCURS IN THE UPCOMING DAYS. ACH && .AVIATION... THE HEAVIER SNOW HAS MOVED NORTH OF THE KTOP AND KFOE TAF SITES. LIGHT TO AT TIMES MODERATE SNOW WILL REDEVELOP LATER THIS AFTERNOON INTO THE EVENING HOURS...WHICH WILL MAY REDUCE VISIBILITIES BELOW 1SM. KMHK MAY KEEP LIGHT SNOW WITH POTENTIALLY SOME HEAVIER SNOW DROPPING VISIBILITIES TO 1/4 MILES AT TIMES. THE SNOW SHOULD END AT ALL TAF SITES AFTER 4Z. CEILINGS WILL VARY FROM IFR TO MVFR DEPENDING ON SNOWFALL RATES. IFR CEILINGS WILL MOVE IN THIS EVENING ON THE NORTHWEST SIDE OF THE SURFACE LOW. THE IFR CEILINGS MAY GRADUALLY RISE TO MVFR CEILINGS LATE TONIGHT. && .TOP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR KSZ010>012- 022>024-026-036>040-054>056-058-059. WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR KSZ008-009- 020-021-034-035. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1232 AM EST THU FEB 21 2013 ...Updated Aviation Discussion... .Short Term (Tonight through Thursday Night)... Issued at 300 PM EST Wed Feb 20 2013 ...A Brief Period of Wintry Weather Coming North of the I-64 Corridor... What a mess as far as dealing with winter weather, as our next system will bring it`s winter weather transition zone right across our forecast area Thursday afternoon to late Thursday night. Until then, the main forecast issue tonight will be cloud cover. Shield of mid/high clouds moving in now is not forecast to last all night. The RAP is advertising additional lower level clouds moving in from the north, a low stratus, which right now is associated with the flow coming off Lake Michigan. Will lean toward the rest of the guidance, which keeps us clearer, overnight, except over the far north. Then mid clouds should increase again as the system mentioned above starts to influence our weather. The atmosphere will saturate from above as an occluded front approaches from the west. Deep isentropic ascent ahead of this front will allow precipitation to start west of the I-65 corridor by late afternoon. With the onset of this precip, expect temperatures to drop a couple of degrees, which will allow for a mix of sleet/snow across the north and cold rain down south. By 00Z, warm air aloft will help to melt the deep freezing layer, allowing for the chance for freezing rain across the north. As the night goes on, the warm air will deepen and expect a transition over the just rain areawide by around 09Z. Forecast uncertainty remains high enough to keep us from issuing an advisory. Went under guidance for temperatures at the surface and aloft. If model forecast temperatures are true, and it should be noted that our forecast errors for this forecast time period average 2-3 degrees, than much more of the area will be mostly rain. Based on this uncertainty, have decided to issue just a special weather statement on the chance for winter weather and hold off on issuing a third-period advisory. .Long Term (Friday through Tuesday Night)... Issued at 326 PM EST Wed Feb 20 2013 The beginning of the long term period will feature a strong shortwave pushing north through the Northern Plains. In its wake, a trough will amplify across the central CONUS this weekend which will work into the Ohio Valley. Another upper ridge will amplify across the Ohio Valley ahead of the next system set to affect the region early next week. A warm front will be lifting north through the region early Friday morning, with the associated synoptic forcing/isentropic ascent lifting north into Ohio. Therefore, precipitation will taper off from southwest to northeast through the day as a dry slot works into the region. Temperatures on Friday will be rather warm, as the surface cold front will remain well off to the west, allowing for southwesterly winds to aid in a quick warmup in the wake of the morning precipitation. The associated cold front will finally push through the region late Friday into early Saturday. Another shortwave will swing through the mean trough Saturday morning, which will induce secondary surface low development across TN/GA. As this wave rides along the departing cold front, it will act to stall its progress. In fact, the 12Z suite of guidance is suggesting there may be enough moisture kicked back into the region to produce some additional precipitation across the Cumberland area as the shortwave and surface low pass by. If this moisture were to get far enough north into the cooler air, then some light freezing rain/drizzle could creep into the northern Bluegrass region Saturday morning. However, this probability looks rather low at this point and will leave precipitation as all rain for now and confined to the far east/southeast portions of the CWA. A ridge will build across the region late Saturday through Monday, providing calm and dry weather conditions. Temperatures will warm each day through the weekend, as temperatures in the lower 40s on Saturday warm into the middle 50s by Monday. Another strong upper level wave will eject out into the Central and Northern Plains on Monday. This system looks very similar to the Thursday/Friday system, spreading a slug of precipitation north in association with a wave of isentropic ascent atop the surface warm front. This time, however, the cooler air will not be in place ahead of the approaching warm front, so any and all precipitation will remain rain. The surface cold front will push through late Monday night into Tuesday morning, dropping temperatures back into the upper 40s Tuesday afternoon. The 20/12Z GFS advertises the surface low tracking across Indiana and Ohio, which would bring some wrap-around precipitation to portions of southern Indiana and northern Kentucky Tuesday into early Wednesday. However, with a strong upper ridge in place, this system will struggle dropping southeast like the GFS suggests. Therefore, will favor the ECMWF and GFS ensembles, lifting the surface low and its associated wrap-around precipitation further north, thus keeping the forecast dry through the remainder of the long term period. && .Aviation (06Z TAF Issuance)... Issued at 1232 AM EST Thu Feb 21 2013 Front half of the upcoming TAF period is fairly quiet as VFR conditions will hold across the region with a very light northeasterly surface flow. Clouds will increase throughout the daytime hours as moisture streams in from the west. Initially dry atmosphere will take some time to moisten up during the day but precipitation looks to break out across the TAF sites towards 22/00Z. Latest guidance continues to show the column moistening up during the late afternoon hours. As column saturates to near the surface by the evening hours, the evaporative cooling associated with the moistening will allow surface temperatures to drop to near or just below freezing at KSDF and KLEX. Warm air advection aloft will result in a gradual warming above the sub-freezing layer at the surface resulting in a profile for freezing rain and sleet to develop. A mix of freezing rain and sleet looks increasingly likely at KSDF between 22/02 and 22/06Z before low-level warm air advection pushes surface temperatures up above freezing resulting in a change back over to plain rain. Over at KLEX, models prog stronger surface cooling resulting in a period of freezing rain likely from 22/00Z through the end of the TAF period. Depending on the amount of warm air aloft, some sleet is possible, but it looks like the warm layer aloft will be sufficiently deep enough to have precip generally in the form of freezing rain. So for now, will just carry FZRA in the TAF from 22/00Z through the end of the period. Further south at KBWG, low-level thermal profiles show plenty of warm air to keep the precipitation as all rain Thursday night. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Short Term.......RJS Long Term........KJD Aviation.........MJ
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
957 PM EST FRI FEB 22 2013 .SYNOPSIS... A WARM FRONT WILL LIFT NORTHWARD INTO THE AREA TONIGHT. A WEAK COLD FRONT WILL MOVE ACROSS THE AREA ON SATURDAY...FOLLOWED BY BUILDING HIGH PRESSURE SUNDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... MADE MINOR ADJUSTMENTS TO OVERNIGHT LOWS USING LATEST LAMP NUMBERS. HAVE REMOVED MENTION OF FZDZ. PREVIOUS FORECAST... THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A CLOSED 500MB LOW CENTERED ACROSS THE UPPER MIDWEST. AT THE SURFACE...AN OCCLUDED FRONT EXTENDS FROM THE LOW IN THE TN VALLEY. FROM THE OCCLUDED FRONT...A WARM EXTENDS EASTWARD INTO NORTH-CENTRAL WV. WITH A DRY LAYER IN PLACE ABOVE 800MB...ANY LINGERING PRECIPITATION IN WEAK LIFT AHEAD OF THE FRONT HAS BEEN IN THE FORM OF DRIZZLE OR FREEZING DRIZZLE ACROSS THE AREA. LOCATIONS NORTH OF PITTSBURGH AND ACROSS THE LAUREL HIGHLANDS/ALLEGHENY FRONT REMAIN BELOW FREEZING. TONIGHT...LOW-LEVEL MOISTURE WILL LINGER ACROSS THE AREA NORTH AND EAST OF PITTSBURGH AS A COLD FRONT APPROACHES FROM THE WEST. RAP/GFS/NAM SOUNDINGS CONTINUE TO INDICATE A DRY DENDRITIC GROWTH ZONE WITH A SATURATED LAYER FROM 800MB TO THE SURFACE. THUS...HAVE CONTINUED MENTIONING OF DZ/FZDZ FOR LOCATIONS NORTH AND EAST OF PITTSBURGH. TEMPS WILL BE FAIRLY STEADY OVERNIGHT...RANGING FROM THE LOWER 30S NORTH AND EAST OF PITTSBURGH TO THE UPPER 30S IN PORTIONS OF EASTERN OHIO AND NORTH- CENTRAL WV. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... A MODEL CONSENSUS INDICATES THAT THE UPPER LOW WILL SHIFT NORTHEASTWARD INTO THE NORTHERN GREAT LAKES AND A WEAK COLD FRONT WILL SWING ACROSS THE OHIO VALLEY ON SATURDAY. MEANWHILE...A SURFACE LOW WILL MOVE FROM THE SOUTHEAST INTO THE MID- ATLANTIC...PASSING TO THE SOUTHEAST OF THE FORECAST AREA. DESPITE MODEL AGREEMENT IN THE SYNOPTIC SCALE PATTERN...THERE STILL LIES SOME UNCERTAINTY IN RESOLVING PRECIPITATION WITH THE FRONTAL PASSAGE ON SATURDAY. HAVE ONLY GONE WITH SCHC IN WESTERN PA AND CHC ACROSS THE RIDGES ON SATURDAY AS THE WEAK FRONT MAY BE ABLE TO PRODUCE A FEW SHOWERS WHEN IT ENCOUNTERS A BIT MORE AVAILABLE MOISTURE IN WESTERN PA AND NORTHERN WV. OTHERWISE...WENT DRY IN OHIO. FOR PRECIP TYPE...MOSTLY RAIN IS FORECAST AS WAA CONTINUES AHEAD OF THE FRONT. THERE IS STILL SOME UNCERTAINTY AS TO WHETHER COLDER AIR TRAPPED AT THE SURFACE WILL REMAIN IN PLACE NORTH OF PITTSBURGH AND ACROSS THE RIDGES...SO HAVE THE MENTION OF SCHC OR CHC FZRA THERE. FOR TEMPS...SIDED WITH THE WARMER MAV...WITH HIGHS RANGING FROM THE LOWER TO MID 40S ACROSS MUCH OF THE AREA. SATURDAY NIGHT THROUGH MONDAY...THE FRONT WILL PASS EAST OF THE AREA SAT NIGHT WITH THE UPPER LEVEL LOW PASSING NORTH OF THE AREA ON SUNDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE SOUTHWEST SUNDAY NIGHT INTO MONDAY. IN A CYCLONIC MID-LEVEL FLOW SAT NIGHT THAT WILL BECOME MORE NORTHWESTERLY ON SUN...HAVE CHC POPS ACROSS THE I-80 CORRIDOR AND WITH UPSLOPING FOR THE LAUREL HIGHLANDS/ALLEGHENY FRONT. A DRY FORECAST IS IN PLACE SUN NIGHT INTO MONDAY AS THE HIGH MOVES OVER THE REGION. TEMPS WILL BE A FEW DEGREES BELOW NORMAL IN THE WAKE OF THE FRONT ON SUNDAY BEFORE MODERATING TO 5 TO 10 DEGREES ABOVE NORMAL ON MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... H5 RDG AXIS WILL MOVE ACRS RGN MON NGT IN ADVC OF A STRONG CLOSED UPR LOW OVER THE SRN PLNS. AS THE WAVE APRCHS LATE MON NGT...WARM AIR ADVCTN WILL DVLP IN EARNEST...PROVIDING SGFNT MSTR FOR WDSPRD PCPN. LGT PCPN XPCD TO SPREAD NEWD LATE MON NGT. CVRG OF PCPN WILL INCR ON TUE AS THE NEGATIVELY-TILTED WAVE CROSSES THE RGN. GIVEN CONSISTENT FCST AMONG THE MODELS AND PERSISTENT MEXMOS PCPN SIGNAL ON TUE...CATEGORICAL POPS WERE INCLUDED ALL ZONES ON TUE. DRY SLOT XPCD TO BRING END TO PCPN TUE NGT. EXACT EVOLUTION OF UPR AIR PATTERN THEREAFTER IS LESS CERTAIN... BUT H5 TROF XPCD TO RMN OVER ERN CONUS. RESULT WILL BE PERSISTENT COLDER AIR AND OCNL SNOW SHWRS AS WLY-NWLY LOW-LVL FLOW DOMINATES THE RGN. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... OVERCAST CEILINGS CAN BE EXPECTED THROUGH THE NIGHT WITH IFR STRATUS CEILINGS ACROSS THE NORTH AND GENERAL MVFR CEILINGS ACROSS THE SOUTH. LITTLE OR NO PRECIPITATION IS EXPECTED OVERNIGHT WHILE SOME PATCHY DRIZZLE CAN NOT BE RULED OUT. CEILINGS WILL IMPROVE SATURDAY WITH THE HEATING OF THE DAY CAUSING ALL PORTS TO LIFT INTO VFR BROKEN CEILINGS. .OUTLOOK.../SATURDAY THROUGH TUESDAY/... IFR WEATHER IS POSSIBLE MONDAY NIGHT INTO TUESDAY WITH THE NEXT WEATHER SYSTEM...OTHERWISE GENERAL VFR CONDITIONS CAN BE EXPECTED FOR THE REMAINDER OF THE EXTENDED PERIOD. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR MDZ001. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ007>009-015-016-022-023. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
929 PM EST FRI FEB 22 2013 .SYNOPSIS... A WARM FRONT WILL LIFT NORTHWARD INTO THE AREA TONIGHT. A WEAK COLD FRONT WILL MOVE ACROSS THE AREA ON SATURDAY...FOLLOWED BY BUILDING HIGH PRESSURE SUNDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... MADE MINOR ADJUSTMENTS TO OVERNIGHT LOWS USING LATEST LAMP NUMBERS. WILL CONTINUE WITH ADV UNTIL 10PM AS TEMPS IN THE REGION ARE STILL BELOW FREEZING AND THERE MAY BE AREAS OF FREEZING DRIZZLE. PREVIOUS FORECAST... THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A CLOSED 500MB LOW CENTERED ACROSS THE UPPER MIDWEST. AT THE SURFACE...AN OCCLUDED FRONT EXTENDS FROM THE LOW IN THE TN VALLEY. FROM THE OCCLUDED FRONT...A WARM EXTENDS EASTWARD INTO NORTH-CENTRAL WV. WITH A DRY LAYER IN PLACE ABOVE 800MB...ANY LINGERING PRECIPITATION IN WEAK LIFT AHEAD OF THE FRONT HAS BEEN IN THE FORM OF DRIZZLE OR FREEZING DRIZZLE ACROSS THE AREA. LOCATIONS NORTH OF PITTSBURGH AND ACROSS THE LAUREL HIGHLANDS/ALLEGHENY FRONT REMAIN BELOW FREEZING. TONIGHT...LOW-LEVEL MOISTURE WILL LINGER ACROSS THE AREA NORTH AND EAST OF PITTSBURGH AS A COLD FRONT APPROACHES FROM THE WEST. RAP/GFS/NAM SOUNDINGS CONTINUE TO INDICATE A DRY DENDRITIC GROWTH ZONE WITH A SATURATED LAYER FROM 800MB TO THE SURFACE. THUS...HAVE CONTINUED MENTIONING OF DZ/FZDZ FOR LOCATIONS NORTH AND EAST OF PITTSBURGH. TEMPS WILL BE FAIRLY STEADY OVERNIGHT...RANGING FROM THE LOWER 30S NORTH AND EAST OF PITTSBURGH TO THE UPPER 30S IN PORTIONS OF EASTERN OHIO AND NORTH- CENTRAL WV. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... A MODEL CONSENSUS INDICATES THAT THE UPPER LOW WILL SHIFT NORTHEASTWARD INTO THE NORTHERN GREAT LAKES AND A WEAK COLD FRONT WILL SWING ACROSS THE OHIO VALLEY ON SATURDAY. MEANWHILE...A SURFACE LOW WILL MOVE FROM THE SOUTHEAST INTO THE MID- ATLANTIC...PASSING TO THE SOUTHEAST OF THE FORECAST AREA. DESPITE MODEL AGREEMENT IN THE SYNOPTIC SCALE PATTERN...THERE STILL LIES SOME UNCERTAINTY IN RESOLVING PRECIPITATION WITH THE FRONTAL PASSAGE ON SATURDAY. HAVE ONLY GONE WITH SCHC IN WESTERN PA AND CHC ACROSS THE RIDGES ON SATURDAY AS THE WEAK FRONT MAY BE ABLE TO PRODUCE A FEW SHOWERS WHEN IT ENCOUNTERS A BIT MORE AVAILABLE MOISTURE IN WESTERN PA AND NORTHERN WV. OTHERWISE...WENT DRY IN OHIO. FOR PRECIP TYPE...MOSTLY RAIN IS FORECAST AS WAA CONTINUES AHEAD OF THE FRONT. THERE IS STILL SOME UNCERTAINTY AS TO WHETHER COLDER AIR TRAPPED AT THE SURFACE WILL REMAIN IN PLACE NORTH OF PITTSBURGH AND ACROSS THE RIDGES...SO HAVE THE MENTION OF SCHC OR CHC FZRA THERE. FOR TEMPS...SIDED WITH THE WARMER MAV...WITH HIGHS RANGING FROM THE LOWER TO MID 40S ACROSS MUCH OF THE AREA. SATURDAY NIGHT THROUGH MONDAY...THE FRONT WILL PASS EAST OF THE AREA SAT NIGHT WITH THE UPPER LEVEL LOW PASSING NORTH OF THE AREA ON SUNDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE SOUTHWEST SUNDAY NIGHT INTO MONDAY. IN A CYCLONIC MID-LEVEL FLOW SAT NIGHT THAT WILL BECOME MORE NORTHWESTERLY ON SUN...HAVE CHC POPS ACROSS THE I-80 CORRIDOR AND WITH UPSLOPING FOR THE LAUREL HIGHLANDS/ALLEGHENY FRONT. A DRY FORECAST IS IN PLACE SUN NIGHT INTO MONDAY AS THE HIGH MOVES OVER THE REGION. TEMPS WILL BE A FEW DEGREES BELOW NORMAL IN THE WAKE OF THE FRONT ON SUNDAY BEFORE MODERATING TO 5 TO 10 DEGREES ABOVE NORMAL ON MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... H5 RDG AXIS WILL MOVE ACRS RGN MON NGT IN ADVC OF A STRONG CLOSED UPR LOW OVER THE SRN PLNS. AS THE WAVE APRCHS LATE MON NGT...WARM AIR ADVCTN WILL DVLP IN EARNEST...PROVIDING SGFNT MSTR FOR WDSPRD PCPN. LGT PCPN XPCD TO SPREAD NEWD LATE MON NGT. CVRG OF PCPN WILL INCR ON TUE AS THE NEGATIVELY-TILTED WAVE CROSSES THE RGN. GIVEN CONSISTENT FCST AMONG THE MODELS AND PERSISTENT MEXMOS PCPN SIGNAL ON TUE...CATEGORICAL POPS WERE INCLUDED ALL ZONES ON TUE. DRY SLOT XPCD TO BRING END TO PCPN TUE NGT. EXACT EVOLUTION OF UPR AIR PATTERN THEREAFTER IS LESS CERTAIN... BUT H5 TROF XPCD TO RMN OVER ERN CONUS. RESULT WILL BE PERSISTENT COLDER AIR AND OCNL SNOW SHWRS AS WLY-NWLY LOW-LVL FLOW DOMINATES THE RGN. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... OVERCAST CEILINGS CAN BE EXPECTED THROUGH THE NIGHT WITH IFR STRATUS CEILINGS ACROSS THE NORTH AND GENERAL MVFR CEILINGS ACROSS THE SOUTH. LITTLE OR NO PRECIPITATION IS EXPECTED OVERNIGHT WHILE SOME PATCHY DRIZZLE CAN NOT BE RULED OUT. CEILINGS WILL IMPROVE SATURDAY WITH THE HEATING OF THE DAY CAUSING ALL PORTS TO LIFT INTO VFR BROKEN CEILINGS. .OUTLOOK.../SATURDAY THROUGH TUESDAY/... IFR WEATHER IS POSSIBLE MONDAY NIGHT INTO TUESDAY WITH THE NEXT WEATHER SYSTEM...OTHERWISE GENERAL VFR CONDITIONS CAN BE EXPECTED FOR THE REMAINDER OF THE EXTENDED PERIOD. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR MDZ001. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ007>009-015-016-022-023. WV...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
659 PM EST FRI FEB 22 2013 .SYNOPSIS... A WARM FRONT WILL LIFT NORTHWARD INTO THE AREA TONIGHT. A WEAK COLD FRONT WILL MOVE ACROSS THE AREA ON SATURDAY...FOLLOWED BY BUILDING HIGH PRESSURE SUNDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... MADE MINOR ADJUSTMENTS TO OVERNIGHT LOWS USING LATEST LAMP NUMBERS. WILL CONTINUE WITH ADV UNTIL 10PM AS TEMPS IN THE REGION ARE STILL BELOW FREEZING AND THERE MAY BE AREAS OF FREEZING DRIZZLE. PREVIOUS FORECAST... THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A CLOSED 500MB LOW CENTERED ACROSS THE UPPER MIDWEST. AT THE SURFACE...AN OCCLUDED FRONT EXTENDS FROM THE LOW IN THE TN VALLEY. FROM THE OCCLUDED FRONT...A WARM EXTENDS EASTWARD INTO NORTH-CENTRAL WV. WITH A DRY LAYER IN PLACE ABOVE 800MB...ANY LINGERING PRECIPITATION IN WEAK LIFT AHEAD OF THE FRONT HAS BEEN IN THE FORM OF DRIZZLE OR FREEZING DRIZZLE ACROSS THE AREA. LOCATIONS NORTH OF PITTSBURGH AND ACROSS THE LAUREL HIGHLANDS/ALLEGHENY FRONT REMAIN BELOW FREEZING. TONIGHT...LOW-LEVEL MOISTURE WILL LINGER ACROSS THE AREA NORTH AND EAST OF PITTSBURGH AS A COLD FRONT APPROACHES FROM THE WEST. RAP/GFS/NAM SOUNDINGS CONTINUE TO INDICATE A DRY DENDRITIC GROWTH ZONE WITH A SATURATED LAYER FROM 800MB TO THE SURFACE. THUS...HAVE CONTINUED MENTIONING OF DZ/FZDZ FOR LOCATIONS NORTH AND EAST OF PITTSBURGH. TEMPS WILL BE FAIRLY STEADY OVERNIGHT...RANGING FROM THE LOWER 30S NORTH AND EAST OF PITTSBURGH TO THE UPPER 30S IN PORTIONS OF EASTERN OHIO AND NORTH- CENTRAL WV. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... A MODEL CONSENSUS INDICATES THAT THE UPPER LOW WILL SHIFT NORTHEASTWARD INTO THE NORTHERN GREAT LAKES AND A WEAK COLD FRONT WILL SWING ACROSS THE OHIO VALLEY ON SATURDAY. MEANWHILE...A SURFACE LOW WILL MOVE FROM THE SOUTHEAST INTO THE MID- ATLANTIC...PASSING TO THE SOUTHEAST OF THE FORECAST AREA. DESPITE MODEL AGREEMENT IN THE SYNOPTIC SCALE PATTERN...THERE STILL LIES SOME UNCERTAINTY IN RESOLVING PRECIPITATION WITH THE FRONTAL PASSAGE ON SATURDAY. HAVE ONLY GONE WITH SCHC IN WESTERN PA AND CHC ACROSS THE RIDGES ON SATURDAY AS THE WEAK FRONT MAY BE ABLE TO PRODUCE A FEW SHOWERS WHEN IT ENCOUNTERS A BIT MORE AVAILABLE MOISTURE IN WESTERN PA AND NORTHERN WV. OTHERWISE...WENT DRY IN OHIO. FOR PRECIP TYPE...MOSTLY RAIN IS FORECAST AS WAA CONTINUES AHEAD OF THE FRONT. THERE IS STILL SOME UNCERTAINTY AS TO WHETHER COLDER AIR TRAPPED AT THE SURFACE WILL REMAIN IN PLACE NORTH OF PITTSBURGH AND ACROSS THE RIDGES...SO HAVE THE MENTION OF SCHC OR CHC FZRA THERE. FOR TEMPS...SIDED WITH THE WARMER MAV...WITH HIGHS RANGING FROM THE LOWER TO MID 40S ACROSS MUCH OF THE AREA. SATURDAY NIGHT THROUGH MONDAY...THE FRONT WILL PASS EAST OF THE AREA SAT NIGHT WITH THE UPPER LEVEL LOW PASSING NORTH OF THE AREA ON SUNDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE SOUTHWEST SUNDAY NIGHT INTO MONDAY. IN A CYCLONIC MID-LEVEL FLOW SAT NIGHT THAT WILL BECOME MORE NORTHWESTERLY ON SUN...HAVE CHC POPS ACROSS THE I-80 CORRIDOR AND WITH UPSLOPING FOR THE LAUREL HIGHLANDS/ALLEGHENY FRONT. A DRY FORECAST IS IN PLACE SUN NIGHT INTO MONDAY AS THE HIGH MOVES OVER THE REGION. TEMPS WILL BE A FEW DEGREES BELOW NORMAL IN THE WAKE OF THE FRONT ON SUNDAY BEFORE MODERATING TO 5 TO 10 DEGREES ABOVE NORMAL ON MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... H5 RDG AXIS WILL MOVE ACRS RGN MON NGT IN ADVC OF A STRONG CLOSED UPR LOW OVER THE SRN PLNS. AS THE WAVE APRCHS LATE MON NGT...WARM AIR ADVCTN WILL DVLP IN EARNEST...PROVIDING SGFNT MSTR FOR WDSPRD PCPN. LGT PCPN XPCD TO SPREAD NEWD LATE MON NGT. CVRG OF PCPN WILL INCR ON TUE AS THE NEGATIVELY-TILTED WAVE CROSSES THE RGN. GIVEN CONSISTENT FCST AMONG THE MODELS AND PERSISTENT MEXMOS PCPN SIGNAL ON TUE...CATEGORICAL POPS WERE INCLUDED ALL ZONES ON TUE. DRY SLOT XPCD TO BRING END TO PCPN TUE NGT. EXACT EVOLUTION OF UPR AIR PATTERN THEREAFTER IS LESS CERTAIN... BUT H5 TROF XPCD TO RMN OVER ERN CONUS. RESULT WILL BE PERSISTENT COLDER AIR AND OCNL SNOW SHWRS AS WLY-NWLY LOW-LVL FLOW DOMINATES THE RGN. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MEDIUM...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. LOW TO MEDIUM CONFIDENCE FORECAST. AREA OF FZRA CONTINUES TO EXIT QUICKLY WITH PATCHY DRIZZLE AND FREEZING DRIZZLE IN ITS WAKE. BRIEF IFR WX WILL LAST AT PIT METRO TERMINALS AND FKL/DUJ THRU 20Z. DRY SLOT THAT IS RACING NE FROM SERN OH AND WV PER LOW LEVEL DOWNSLOPE WINDS AND SW FLOW ALOFT REACHES ZZV - PIT - LBE THIS AFTN. BKN VFR CIGS WILL CARRY THROUGH THE EVENING HOURS AT THE AFOREMENTIONED AIRPORTS. HARDEST PART OF THE FORECAST IS WHAT WILL HAPPEN OVERNIGHT. ALL OF THE STATISTICAL GUIDANCE YIELDS MVFR / IFR CIGS WHILE UPSTREAM OBS SAY IT WILL BE VFR. PLAYED THE OPTIMISTIC ROLE FOR MOST TERMINALS...SAVE FOR FKL/DUJ/ZZV WHERE MVFR CIGS SHOULD OCCUR FOR AT LEAST PART OF THE NIGHT. ANY MVFR CIGS LIFT BY MID MRNG DUE TO LIGHT SW WINDS. WHERE TAFS COULD GO WRONG: - MVFR CIGS COULD LINGER THROUGH THE AFTN - MVFR/IFR CIGS MAY DEVELOP DURING THE OVERNIGHT HOURS AREA WIDE - MVFR CIGS COULD TAKE UNTIL 15-17Z TO LIFT .OUTLOOK.../SATURDAY THROUGH TUESDAY/... IFR WEATHER IS POSSIBLE MONDAY NIGHT INTO TUESDAY WITH THE NEXT WEATHER SYSTEM. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR MDZ001. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ007>009-015-016-022-023. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
359 PM EST THU FEB 21 2013 .SYNOPSIS... ISSUED AT 330 PM EST THU FEB 21 2013 SNOW WILL SPREAD NORTHEAST ACROSS THE AREA OVERNIGHT INTO FRIDAY MORNING. A QUICK 1 TO 2 INCHES OF SNOW MAY AFFECT THE FRIDAY MORNING COMMUTE. THIS WILL BE FOLLOWED BY A TRANSITION TO FREEZING DRIZZLE LATER IN THE DAY. A CHANCE OF WINTRY PRECIPITATION WILL PERSIST THROUGH SATURDAY NIGHT. THE NEXT CHANCES FOR PRECIPITATION WILL BE MONDAY NIGHT AND TUESDAY...WHEN A MIX OF RAIN AND SNOW IS EXPECTED. TEMPERATURES WILL MODERATE NEXT WEEK WITH HIGHS REACHING THE UPPER 30S. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 330 PM EST THU FEB 21 2013 WILL BE ISSUING A WINTER WEATHER ADVISORY FOR OUR SOUTHERN CWFA TO ACCOUNT FOR POSSIBLE BRIEF INTENSE SNOWFALL DURING THE FRIDAY MORNING COMMUTE. CALIBRATED SREF GUIDANCE SHOWS GREATER THAN 1 INCH PER HOUR SNOWFALL PROBABILITIES ACROSS OUR SOUTHERN COUNTY WARNING AREA IN THE 12-15Z TIMEFRAME FRIDAY. ALSO LATEST GRR SNOWTOOL GUIDANCE FROM THE RAP SUGGESTS THAT 1"/HR RATES WILL BE POSSIBLE AFTER 10Z. ADVISORY WILL BE COMING OUT SHORTLY. AFTER THIS INITIAL BURST OF SNOWFALL...AGREE WITH THE PREVIOUS DISCUSSION THAT IMPACTS SHOULD BE MINOR. THE RESPONSIBLE SYSTEM CURRENTLY IN THE PLAINS WILL FILL AS IT SHEARS NORTHEAST. BEHIND THE NARROW BUT POTENTIALLY INTENSE BAND OF WARM ADVECTION SNOW...ALL BUT THE EXTREME NORTHERN PART OF THE FORECAST AREA DESATURATES IN THE DGZ DURING THE LATE MORNING...MEANING A TRANSITION TO FREEZING DRIZZLE AND THEN POSSIBLY DRIZZLE AS SURFACE TEMPERATURES WARM. ICE ACCUMULATION IS EXPECTED TO BE MINIMAL... ESPECIALLY WITH THE MITIGATING EFFECTS OF SNOW COVER...RESIDUAL SALT...AND DAYTIME INSOLATION ALL DISCUSSED IN THE PREVIOUS AFD. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 330 PM EST THU FEB 21 2013 A HIGH PRESSURE RIDGE WILL PRODUCE DRY WX WITH SEASONABLY COOL TEMPERATURES SUNDAY THROUGH SUNDAY NIGHT. LOW PRESSURE TRACKING NE INTO OUR REGION WILL BRING A SLIGHT CHANCE FOR A MIX OF LIGHT RAIN AND LIGHT SNOW AS EARLY AS MONDAY BASED ON 12Z GFS GUIDANCE. HOWEVER THE MUCH BETTER CHANCE FOR MIXED PCPN SHOULD HOLD OFF UNTIL LATE MONDAY NIGHT AND TUESDAY AS SUGGESTED BY THE SLOWER AND PREFERRED ECMWF 12Z GUIDANCE SOLUTION (WHICH IS CONSISTENT WITH PCPN TIMING FROM THE 00Z RUN). TEMPS WILL UNDERGO A GRADUAL MODERATING TREND DURING THE EARLY TO MIDDLE PORTION OF NEXT WEEK WITH MAX TEMPS EXPECTED TO REACH THE UPPER 30S TO LOWER 40S BY TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY) ISSUED AT 1225 PM EST THU FEB 21 2013 MVFR CONDITIONS WILL CONTINUE AT ALL THE TERMINALS THIS AFTERNOON AND EVENING DUE TO LOW CLOUDS WITH CLOUD BASES OF 1.5 TO 2 KFT AGL. CONDITIONS WILL DETERIORATE FROM MVFR TO IFR DURING THE EARLY MORNING HOURS FRIDAY AS A BAND OF SNOW MOVES IN FROM SW TO NE. IFR/LIFR CONDITIONS WILL CONTINUE FRIDAY MORNING THROUGH EARLY FRIDAY AFTERNOON AS CIGS LOWER AND SNOW CONTINUES. THERE IS ALSO SOME POTENTIAL FOR FREEZING DRIZZLE FROM MID MORNING FRIDAY THROUGH 18Z FRIDAY MAINLY FOR THE TERMINALS ALONG THE I-94 CORRIROR. NOT ENOUGH POTENTIAL IN THIS TO WARRANT INCLUSION IN THE TERMINAL FCSTS JUST YET... BUT WE WILL CONTINUE TO MONITOR FOR THIS POTENTIAL. && .MARINE... ISSUED AT 359 PM EST THU FEB 21 2013 AFTER FURTHER CONSIDERATION...ISSUED A NEW SMALL CRAFT ADVISORY BEGINNING TONIGHT TO ACCOUNT FOR STRENGTHENING EAST WINDS TOWARDS MORNING. ALTHOUGH WAVE GROWTH WILL BE LIMITED SOMEWHAT BY POOR FETCH...SUSTAINED WINDS WELL IN EXCESS OF 20 KTS TOWARDS SUNRISE WILL GREATLY INCREASE THE HAZARD. && .HYDROLOGY... ISSUED AT 330 PM EST THU FEB 21 2013 WITH ADDITIONAL QPF EXPECTED TO STAY WELL UNDER HALF AN INCH...THERE ARE NO CONCERNS AT THIS TIME. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY FROM 4 AM TO 1 PM EST FRIDAY FOR MIZ050- 056>059-064>067-071>074. LM...SMALL CRAFT ADVISORY FROM 1 AM FRIDAY TO 5 PM EST SATURDAY FOR LMZ844>849. && $$ SYNOPSIS...TJT SHORT TERM...TJT LONG TERM...LAURENS AVIATION...LAURENS HYDROLOGY...TJT MARINE...TJT
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
330 PM EST THU FEB 21 2013 .SYNOPSIS... ISSUED AT 330 PM EST THU FEB 21 2013 SNOW WILL SPREAD NORTHEAST ACROSS THE AREA OVERNIGHT INTO FRIDAY MORNING. A QUICK 1 TO 2 INCHES OF SNOW MAY AFFECT THE FRIDAY MORNING COMMUTE. THIS WILL BE FOLLOWED BY A TRANSITION TO FREEZING DRIZZLE LATER IN THE DAY. A CHANCE OF WINTRY PRECIPITATION WILL PERSIST THROUGH SATURDAY NIGHT. THE NEXT CHANCES FOR PRECIPITATION WILL BE MONDAY NIGHT AND TUESDAY...WHEN A MIX OF RAIN AND SNOW IS EXPECTED. TEMPERATURES WILL MODERATE NEXT WEEK WITH HIGHS REACHING THE UPPER 30S. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 330 PM EST THU FEB 21 2013 WILL BE ISSUING A WINTER WEATHER ADVISORY FOR OUR SOUTHERN CWFA TO ACCOUNT FOR POSSIBLE BRIEF INTENSE SNOWFALL DURING THE FRIDAY MORNING COMMUTE. CALIBRATED SREF GUIDANCE SHOWS GREATER THAN 1 INCH PER HOUR SNOWFALL PROBABILITIES ACROSS OUR SOUTHERN COUNTY WARNING AREA IN THE 12-15Z TIMEFRAME FRIDAY. ALSO LATEST GRR SNOWTOOL GUIDANCE FROM THE RAP SUGGESTS THAT 1"/HR RATES WILL BE POSSIBLE AFTER 10Z. ADVISORY WILL BE COMING OUT SHORTLY. AFTER THIS INITIAL BURST OF SNOWFALL...AGREE WITH THE PREVIOUS DISCUSSION THAT IMPACTS SHOULD BE MINOR. THE RESPONSIBLE SYSTEM CURRENTLY IN THE PLAINS WILL FILL AS IT SHEARS NORTHEAST. BEHIND THE NARROW BUT POTENTIALLY INTENSE BAND OF WARM ADVECTION SNOW...ALL BUT THE EXTREME NORTHERN PART OF THE FORECAST AREA DESATURATES IN THE DGZ DURING THE LATE MORNING...MEANING A TRANSITION TO FREEZING DRIZZLE AND THEN POSSIBLY DRIZZLE AS SURFACE TEMPERATURES WARM. ICE ACCUMULATION IS EXPECTED TO BE MINIMAL... ESPECIALLY WITH THE MITIGATING EFFECTS OF SNOW COVER...RESIDUAL SALT...AND DAYTIME INSOLATION ALL DISCUSSED IN THE PREVIOUS AFD. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 330 PM EST THU FEB 21 2013 A HIGH PRESSURE RIDGE WILL PRODUCE DRY WX WITH SEASONABLY COOL TEMPERATURES SUNDAY THROUGH SUNDAY NIGHT. LOW PRESSURE TRACKING NE INTO OUR REGION WILL BRING A SLIGHT CHANCE FOR A MIX OF LIGHT RAIN AND LIGHT SNOW AS EARLY AS MONDAY BASED ON 12Z GFS GUIDANCE. HOWEVER THE MUCH BETTER CHANCE FOR MIXED PCPN SHOULD HOLD OFF UNTIL LATE MONDAY NIGHT AND TUESDAY AS SUGGESTED BY THE SLOWER AND PREFERRED ECMWF 12Z GUIDANCE SOLUTION (WHICH IS CONSISTENT WITH PCPN TIMING FROM THE 00Z RUN). TEMPS WILL UNDERGO A GRADUAL MODERATING TREND DURING THE EARLY TO MIDDLE PORTION OF NEXT WEEK WITH MAX TEMPS EXPECTED TO REACH THE UPPER 30S TO LOWER 40S BY TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY) ISSUED AT 1225 PM EST THU FEB 21 2013 MVFR CONDITIONS WILL CONTINUE AT ALL THE TERMINALS THIS AFTERNOON AND EVENING DUE TO LOW CLOUDS WITH CLOUD BASES OF 1.5 TO 2 KFT AGL. CONDITIONS WILL DETERIORATE FROM MVFR TO IFR DURING THE EARLY MORNING HOURS FRIDAY AS A BAND OF SNOW MOVES IN FROM SW TO NE. IFR/LIFR CONDITIONS WILL CONTINUE FRIDAY MORNING THROUGH EARLY FRIDAY AFTERNOON AS CIGS LOWER AND SNOW CONTINUES. THERE IS ALSO SOME POTENTIAL FOR FREEZING DRIZZLE FROM MID MORNING FRIDAY THROUGH 18Z FRIDAY MAINLY FOR THE TERMINALS ALONG THE I-94 CORRIROR. NOT ENOUGH POTENTIAL IN THIS TO WARRANT INCLUSION IN THE TERMINAL FCSTS JUST YET... BUT WE WILL CONTINUE TO MONITOR FOR THIS POTENTIAL. && .MARINE... ISSUED AT 330 PM EST THU FEB 21 2013 BASED ON WEBCAMS AND LATEST LOCAL RUN OF THE GLERL...CANCELLED THE SMALL CRAFT ADVISORY. && .HYDROLOGY... ISSUED AT 330 PM EST THU FEB 21 2013 WITH ADDITIONAL QPF EXPECTED TO STAY WELL UNDER HALF AN INCH...THERE ARE NO CONCERNS AT THIS TIME. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...TJT SHORT TERM...TJT LONG TERM...LAURENS AVIATION...LAURENS HYDROLOGY...TJT MARINE...TJT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
548 AM CST THU FEB 21 2013 .UPDATE...FOR 12Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 404 AM CST THU FEB 21 2013/ TWO WEATHER CONCERNS COMING UP IN THE NEXT WEEK. FIRST WILL BE SNOW FROM THURSDAY NIGHT THROUGH FRIDAY NIGHT...WITH ANOTHER POTENTIAL SNOW MAKER FOR NEXT WEEK. MODEL AGREEMENT REMAINS HIGH WITH THE FIRST SYSTEM...BUT THERE REMAINS QUITE A BIT OF SPREAD WITH SYSTEM TWO...ESPECIALLY IN TERMS OF TIMING. OUR FIRST WAVE IS EASILY IDENTIFIABLE THIS MORNING ON WATER VAPOR IMAGERY THIS NEAR ALBUQUERQUE...WITH AN IMPRESSIVE CLUSTER OF THUNDERSTORMS MOVING NORTH OUT OF OK THAT IS ON THE NOSE OF 90 KT MID LEVEL JET ROUNDING THE BASE OF THE TROUGH. UP HERE...THE MPX AREA REMAINS UNDER THE INFLUENCE OF A 1040 MB ARCTIC HIGH CENTERED OVER NW ONTARIO...WITH A RIDGE AXIS DOWN THE ST. CROIX/MIS RIVER VALLEYS. THIS HIGH IS THE SOURCE FOR OUR LOW LEVEL AIR...WITH DEWPS HOVERING AROUND ZERO AS A RESULT. TEMPERATURES ARE ALSO A FEW DEGREES ON EITHER SIDE OF ZERO AND HAVE BEEN HELD IN CHECK BY A THIN BLANKET OF CIRRUS. FOR TODAY...THE HIGH WILL KEEP ANY PRECIP SOUTH OF THE MPX CWA...WITH THICKENING HIGH CLOUDS HELPING TO KEEP TEMPERATURES A LITTLE BIT MORE UNIFORM THAN WHAT WAS SEEN YESTERDAY. FOR US...THE HEAVY SHIELD OF PRECIP MOVING ACROSS SRN KANSAS WILL BE WHAT BRINGS THIS REGION MOST OF ITS SNOW. AT 3AM...THIS PRECIP WAS STILL ALL SOUTH OF I-70...SO IT WILL BE A WHILE BEFORE REACHING THE I-90 CORRIDOR. MODELS HAVE MAINTAINED GOOD AGREEMENT WITH THEIR HANDLING OF THE SYSTEM...WITH THE ONE OUTLIER CONTINUING TO BE THE NAM...WHICH IS STILL RUNNING A BIT HIGHER WITH QPF ACROSS MN/WRN WI...THOUGH IT HAS COME DOWN MORE IN LINE WITH THE ECMWF/GFS/SREF/GEM. FOR TIMING PRECIP WITH THIS SYSTEM... FAVORED THE SREF TIMING AS IT IS BASICALLY IN LINE WITH EVERYTHING ELSE AND DOES ACCOUNT FOR SOME MINIMAL SPREAD. FOR QPF...A BLEND OF THE ECMWF/GFS/SREF WAS USED...ALONG WITH SNOW RATIOS OF 15-16:1. SO WHAT CHANGED? FIRST...SLOWED EVEN FURTHER HOW QUICKLY THINGS MOVE NORTH TONIGHT...WITH NO CATEGORICAL POPS IN THE SOUTH UNTIL AFTER 3Z AND DELAYING THE START OF SNOW ACROSS THE FAR NRN CWA UNTIL AFTER 9Z. QPF/SNOWFALL WITH THIS FORECAST HAD ONLY A SLIGHT NUDGE DOWN IN BOTH. CURRENT GRIDS HAVE 4-5 INCHES ALONG AND SOUTH OF A ST. JAMES...TO MANKATO...TO RICE LAKE LINE. 3 TO 4 INCHES ARE CURRENTLY INDICATED NORTHWEST TO A REDWOOD FALLS...TO MONTICELLO...TO CAMBRIDGE LINE...WHICH IS BASICALLY AS FAR NW AS CURRENT ADVISORY GOES...SO NO AREAL EXPANSIONS WERE NEEDED WITH IT TONIGHT. PART OF THE REASON TOTALS ARE AS HIGH AS THEY ARE IS THAT AS THIS SYSTEM SLOWLY FILLS FRIDAY INTO SATURDAY...LIGHT SNOW WILL PERSIST ACROSS MUCH OF THE AREA RIGHT THROUGH FRIDAY NIGHT...HELPING BOOST SNOW TOTALS SOME...ESPECIALLY ACROSS WRN WI. LEFT STARTING/END TIMES UNCHANGED WITH ADVY...BUT WITH SNOW LIKELY TO PERSIST THROUGH FRIDAY NIGHT...EXTENDING THE ADVISORY INTO SATURDAY MORNING ACROSS ERN AREAS WILL BE SOMETHING FUTURE SHIFTS WILL NEED TO THINK ABOUT. MODELS SHOW SNOW FINALLY CUTTING OFF DURING THE DAY SATURDAY AS UPPER LOW BEGINS TO EJECT EAST ACROSS THE GREAT LAKES...ALLOWING SFC RIDGE TO MOVE IN. GOOD NEWS THOUGH IS WE WILL NOT SEE A GOOD PUNCH OF ARCTIC AIR BEHIND THIS SYSTEM...SO WILL MAINTAIN HIGHS IN THE 20S/30S INTO THE WEEKEND. NEXT SYSTEM TO POTENTIALLY IMPACT THE AREA DURING THE FIRST HALF OF NEXT WEEK CAN BE FOUND OUT IN THE FAR WEST END OF THE ALEUTIAN ISLAND CHAIN AT THE MOMENT. STILL SEE A DECENT AMOUNT OF SPREAD WITH THIS SYSTEM...WITH THE GFS PUSHING SNOW IN BY SUNDAY NIGHT...WHILE THE ECMWF/GEM DO NOT REALLY BRING ANYTHING IN UNTIL TUESDAY. THE GEFS MEAN LOOKS SIMILAR TO THE GFS...WITH THE FIM HAVING TIMING MORE IN LINE WITH THE GEM/ECMWF...BUT TAKES THE SYSTEM WELL SOUTHEAST OF MN/WRN WI. GIVEN ALL THE SPREAD IN TIMING...MODEL BLEND USED IN THE EXTENDED PORTION OF THIS FORECAST WOUND UP PLASTERING CHANCE POPS FROM SUNDAY NIGHT THROUGH TUESDAY. THIS SECOND SYSTEM DOES LOOK SOMEWHAT SIMILAR TO WHAT THE FIRST STORM WILL BE LIKE...WITH AN OCCLUDED AND FILLING IN LOW MOVING NORTH OUT OF THE SOUTHERN PLAINS...RESULTING IN HIGHEST PRECIP AMOUNTS SOUTH OF THE AREA. ONE DIFFERENCE THOUGH BETWEEN NEXT WEEKS SYSTEM AND THIS WEEKS IS THAT TEMPS WILL BE RUNNING 5 TO 10 DEGREES WARMER NEXT WEEK...THOUGH SHOULD STILL BE JUST COLD ENOUGH IN THE EAST TO KEEP THINGS AS ALL SNOW. && .AVIATION.../12Z TAF ISSUANCE/ SQUEEZE PLAY FOR THE LOW CLOUDS TODAY...WITH MVFR/IFR CLOUDS LIFTING NORTHEAST FROM KS/NE...AND STRATUS OOZING SOUTHWEST FROM LAKE SUPERIOR AND THE UP OF MI. EXPECT THE SOUTHERN BATCH TO SPREAD FROM SOUTHERN MN TO REACH KRWF-KAXN-KSTC BETWEEN 03Z AND 09Z FRIDAY...WITH EASTERN SITES /KEAU-KRNH-KMSP/ LIKELY SEEING LOW CLOUDS ARRIVE EARLIER THIS AFTERNOON. BASED UPON CURRENT SATELLITE IMAGERY AND HRRR/RAP MODELS...HAVE INTRODUCED A SCT-BKN MVFR CLOUD LEVEL BETWEEN 17Z AND 20Z AT KEAU-KRNH-KMSP...BECOMING OVERCAST BETWEEN 21Z THURSDAY AND 00Z FRIDAY. SNOW IS EXPECTED TO BLOSSOM OVER THE AREA AFTER 05Z FRIDAY...WITH IFR VSBYS AND MVFR CIGS BECOMING COMMON THROUGH FRIDAY MORNING. WINDS FROM 050-090 DEGREES WILL PREVAIL...MAINLY FROM 5 TO 10 KTS. KMSP... SCT CLOUDS AROUND 2500 FT MAY MOVE INTO THE AIRPORT FROM THE NORTHEAST THIS AFTERNOON. PER HRRR AND RAP SOLUTIONS...INTRODUCED A 21Z SCT MVFR CLOUD GROUP...WITH OVC CIGS ARRIVING AROUND 00Z. STILL EXPECT SNOW TO HOLD OFF UNTIL AFTER 05Z...AS WE/LL STILL BE WAITING ON THE FORCING/DYNAMICS TO ARRIVE FROM THE SOUTHWEST. THE TIME FRAME FOR THE WORST CONDITIONS STILL LOOKS TO BE BETWEEN 08Z AND 12Z...WHEN VSBYS BETWEEN 1/2SM AND 1 SM ARE EXPECTED. WINDS BETWEEN 080-090 WILL PREVAIL TODAY...WITH 050-070 FOR TONIGHT. SPEEDS BETWEEN 6 KTS AND 10 KTS ARE EXPECTED THROUGH THE PERIOD. /OUTLOOK FOR KMSP/ FRI NIGHT...IFR CIGS AND VSBY EXPECTED...WITH -SN LIKELY. NE WIND 5-15 KT...BECOMING NW LATE. SAT...MVFR CIGS WITH -SN IN THE MORNING. W WIND 5 KT. SUN...VFR CIGS EARLY...MVFR CIGS LATE. CHANCE -SN LATE. SE WINDS BECOMING NE 5 KT. MON...MVFR CIGS WITH CHANCE -SN. NE WINDS 5 TO 10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR BLUE EARTH-BROWN-CARVER-DAKOTA-FARIBAULT- FREEBORN-GOODHUE-HENNEPIN-LE SUEUR-MARTIN-MCLEOD-NICOLLET- REDWOOD-RENVILLE-RICE-SCOTT-SIBLEY-STEELE-WASECA-WATONWAN- WRIGHT. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST FRIDAY FOR ANOKA-CHISAGO-RAMSEY-WASHINGTON. WI...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST FRIDAY FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK- ST. CROIX. && $$ MPG/LS
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1131 AM CST Thu Feb 21 2013 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... Intense winter storm is taking direct aim on the forecast area this morning. Overnight model runs...including the near-term RAP and HRRR models...now indicate a broad swath of 1"+ liquid-equivalent precipitation totals overspreading most of the forecast area with the heaviest axis centered very close to Kansas City. How these precip totals translate into snow and sleet amounts is still somewhat of a question mark given the presence of warm air in the 800-700 hPa layer and a shallow depth of the max dendritic growth region. Seems most methods are giving snow to liquid ratios on the order of 8:1 to 10:1 near I-70...and around 10:1 to 12:1 north of Highway 36. Applying these ratios to expected precip totals now results in a broad swath of 8 to 12 inch snows forecast for most of the forecast area...generally along and north of a Paola...Marshall...Moberly line. These areas are unlikely to see much if any sleet contamination and could see some totals approach or exceed February records (see climate section below). Still expect sleet to fall across areas south of this line, and there could be a good deal of it. Exactly how much sleet falls across these areas will have huge impacts on snow amounts, which could be as low as 3 or 4 inches if sleet lasts several hours...to as much as 8 to 10 inches if sleet is only brief. Freezing rain still appears a possibility for the Clinton/Sedalia/Boonville areas but any icing should be limited to a tenth of an inch or less. Looking upstream, synoptic and mesoscale ascent has become quite strong and is coupled throughout a large depth of the atmosphere. Combine this with strong moisture advection from the south, the result has been an expanding area of heavy precipitation over northern OK and southern KS with several bands of convection feeding into it. In fact, lightning profilers have lit up vividly down there, even in the stratiform precipitation over KS, suggestive of quite a bit of slantwise and even upright instability. This instability will spread into ern KS/wrn MO through the morning and could easily result in occasional thunder and snowfall rates of 2" to 3" per hour. Heaviest precipitation band will spread into northern MO through the afternoon and taper off across the KC area by 21Z or so. However, broad synoptic scale and weak deformation forcing will continue well into the evening and overnight as the upper low moves overhead. This could result in an extra 2" to 5" of snow from late afternoon into the early morning hours particularly north of the Missouri River. Hawblitzel Friday and Saturday... As the system departs, a few lingering snow showers may be possible across far northeast Missouri, but little to no additional snow accumulation is expected. Temperatures will have difficulty rising much on Friday with widespread snow cover and colder air advecting into the region, so have kept high temperatures only a few degrees warmer than Thursday night lows. Frigid temperatures are possible Friday night as surface high pressure drifts over western Missouri, combining the residual snow cover with light winds and clear skies. Warmer air will begin to build into the region on Saturday as the upper low departs, but reaching highs much above freezing will be difficult, especially without strong return flow at low levels. Sunday and Monday... Another deep trough axis will swing through the four corners region on Sunday, bringing a deepening surface low into the southern High Plains by early Monday. This system is currently projected to lift northeast into the region on Monday afternoon, taking a somewhat similar track to the current system; however, there is still a good deal of uncertainty in this forecast. Moisture may be a bit more limited with a smaller window of time to draw from the Gulf, and this more southern track is a very recent trend with the 00z models, so for now have kept probabilities relatively low and maintained a rain or snow precipitation type to cover several possible scenarios. Tuesday through Thursday... Quieter conditions should prevail for the remainder of next week as a more persistent ridge builds over the west. A few snow showers may be possible Tuesday night into early Wednesday as a weak clipper dives in behind the departing upper low, but any snowfall that does occur should be fairly light, and the probability of measurable snow is low. Temperatures will remain below normal as a result of cold air wrapping behind the upper low and additional cold air dropping southeast with the clipper, but should eventually recover when the ridge over the Rockies begins to shift east. Laflin && .CLIMATE... The last time Kansas City officially measured 12" of snow was January 18-19 in 1962 (14.0"). The most recent snowfall greater than 10" was February 24-25 in 1993 (11.1"). Top 10 snowfalls for Kansas City 1. 24.2"...Mar 22-24 1912 2. 15.8"...Feb 11-12 1894 3. 14.6"...Jan 20-21 1958 4. 14.0"...Jan 18-19 1962 5. 13.8"...Mar 14-15 1960 6. 13.7"...Jan 8-9 1930 7. 13.0"...Feb 27-28 1900 8. 12.3"...Mar 29-31 1926 9. 12.2"...Dec 23-24 1918 10. 11.9"...Mar 3-5 1915 Top 5 daily February snowfalls for Kansas City 1. 11.8"...27th 1900 2. 10.5"...4th 1915 3. 8.7"...23rd 1990 4. 8.6"...2nd 1960 5. 8.0"...15th 1960 && .AVIATION... For the 18Z TAFs...Heavy snow will tapper off to light snow this afternoon as dry air aloft works across the terminals from southwest to northeast. This may result in a brief period of improved conditions, going from LIFR to MVFR, but conditions will come back down into the IFR quickly so have left this out of the TAF. Otherwise, precipitation type might convert to, or mix with, freezing drizzle. Light snow is expected to persist through the afternoon and evening hours with additional accumulations. Cutter && .EAX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING until Midnight CST tonight FOR MOZ028>030- 037>040-043>046-053-054. WINTER STORM WARNING until 6 AM CST Friday FOR MOZ001>008- 011>017-020>025-031>033. KS...WINTER STORM WARNING until Midnight CST tonight FOR KSZ057-060- 103>105. WINTER STORM WARNING until 6 AM CST Friday FOR KSZ025-102. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1037 AM CST Thu Feb 21 2013 .UPDATE... /1036 AM CST Thu Feb 21 2013/ ...Shifting heaviest snow band a bit farther south... Morning upper air sounding from Springfield showed a unstable sounding, and sure enough that instability worked north feeding moisture across the southern reaches of the forecast area. This helped fuel thunder-snow that has reached as far north as North Kansas City this morning. Radar trends and satellite imagery are pointing at the heaviest snow band setting up across the southern half of the forecast area this morning, shifting to the northeast through the afternoon hours. Deformation zone snow is developing from northwest Missouri back into south central Kansas, and will likely be what brings significant snow accumulations to far northwest Missouri --this afternoon and this evening--. South of a St Joseph to Kirksville line...snowfall totals have been bumped up with the heaviest snow expected to persist through the early to mid afternoon hours. Totals of greater than 12 inches will be possible as far south as Highway 50. Dry slot is just shy of nosing into the southwest corner of the forecast area, with reports of precipitation type beginning to transit from snow and sleet to freezing drizzle. The Threat of freezing rain continue to look very minimal, but will persist across areas from east central Kansas into central Missouri through the mid- afternoon hours. Cutter && .DISCUSSION... Intense winter storm is taking direct aim on the forecast area this morning. Overnight model runs...including the near-term RAP and HRRR models...now indicate a broad swath of 1"+ liquid-equivalent precipitation totals overspreading most of the forecast area with the heaviest axis centered very close to Kansas City. How these precip totals translate into snow and sleet amounts is still somewhat of a question mark given the presence of warm air in the 800-700 hPa layer and a shallow depth of the max dendritic growth region. Seems most methods are giving snow to liquid ratios on the order of 8:1 to 10:1 near I-70...and around 10:1 to 12:1 north of Highway 36. Applying these ratios to expected precip totals now results in a broad swath of 8 to 12 inch snows forecast for most of the forecast area...generally along and north of a Paola...Marshall...Moberly line. These areas are unlikely to see much if any sleet contamination and could see some totals approach or exceed February records (see climate section below). Still expect sleet to fall across areas south of this line, and there could be a good deal of it. Exactly how much sleet falls across these areas will have huge impacts on snow amounts, which could be as low as 3 or 4 inches if sleet lasts several hours...to as much as 8 to 10 inches if sleet is only brief. Freezing rain still appears a possibility for the Clinton/Sedalia/Boonville areas but any icing should be limited to a tenth of an inch or less. Looking upstream, synoptic and mesoscale ascent has become quite strong and is coupled throughout a large depth of the atmosphere. Combine this with strong moisture advection from the south, the result has been an expanding area of heavy precipitation over northern OK and southern KS with several bands of convection feeding into it. In fact, lightning profilers have lit up vividly down there, even in the stratiform precipitation over KS, suggestive of quite a bit of slantwise and even upright instability. This instability will spread into ern KS/wrn MO through the morning and could easily result in occasional thunder and snowfall rates of 2" to 3" per hour. Heaviest precipitation band will spread into northern MO through the afternoon and taper off across the KC area by 21Z or so. However, broad synoptic scale and weak deformation forcing will continue well into the evening and overnight as the upper low moves overhead. This could result in an extra 2" to 5" of snow from late afternoon into the early morning hours particularly north of the Missouri River. Hawblitzel Friday and Saturday... As the system departs, a few lingering snow showers may be possible across far northeast Missouri, but little to no additional snow accumulation is expected. Temperatures will have difficulty rising much on Friday with widespread snow cover and colder air advecting into the region, so have kept high temperatures only a few degrees warmer than Thursday night lows. Frigid temperatures are possible Friday night as surface high pressure drifts over western Missouri, combining the residual snow cover with light winds and clear skies. Warmer air will begin to build into the region on Saturday as the upper low departs, but reaching highs much above freezing will be difficult, especially without strong return flow at low levels. Sunday and Monday... Another deep trough axis will swing through the four corners region on Sunday, bringing a deepening surface low into the southern High Plains by early Monday. This system is currently projected to lift northeast into the region on Monday afternoon, taking a somewhat similar track to the current system; however, there is still a good deal of uncertainty in this forecast. Moisture may be a bit more limited with a smaller window of time to draw from the Gulf, and this more southern track is a very recent trend with the 00z models, so for now have kept probabilities relatively low and maintained a rain or snow precipitation type to cover several possible scenarios. Tuesday through Thursday... Quieter conditions should prevail for the remainder of next week as a more persistent ridge builds over the west. A few snow showers may be possible Tuesday night into early Wednesday as a weak clipper dives in behind the departing upper low, but any snowfall that does occur should be fairly light, and the probability of measurable snow is low. Temperatures will remain below normal as a result of cold air wrapping behind the upper low and additional cold air dropping southeast with the clipper, but should eventually recover when the ridge over the Rockies begins to shift east. Laflin && .CLIMATE... The last time Kansas City officially measured 12" of snow was January 18-19 in 1962 (14.0"). The most recent snowfall greater than 10" was February 24-25 in 1993 (11.1"). Top 10 snowfalls for Kansas City 1. 24.2"...Mar 22-24 1912 2. 15.8"...Feb 11-12 1894 3. 14.6"...Jan 20-21 1958 4. 14.0"...Jan 18-19 1962 5. 13.8"...Mar 14-15 1960 6. 13.7"...Jan 8-9 1930 7. 13.0"...Feb 27-28 1900 8. 12.3"...Mar 29-31 1926 9. 12.2"...Dec 23-24 1918 10. 11.9"...Mar 3-5 1915 Top 5 daily February snowfalls for Kansas City 1. 11.8"...27th 1900 2. 10.5"...4th 1915 3. 8.7"...23rd 1990 4. 8.6"...2nd 1960 5. 8.0"...15th 1960 && .AVIATION... For the 12Z TAFs...major winter storm will impact all terminals for much of the day with very heavy snow rates of 1 to 2 inches per hour, possibly more. Occasional lightning is also possible. This activity is right on the doorstep, so will go ahead and introduce heavy snow to the KC and STJ terminals right at the onset of the TAF period. The heavy nature of the snow is likely to bring every airport below operational minimums at times. Heaviest snow will gradually taper off across KC/STJ by mid afternoon, and across central and northeast MO late afternoon. However, additional light snow through the evening could produce additional light accumulations and prolonged IFR conditions through the night. Hawblitzel && .EAX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING until Midnight CST tonight FOR MOZ028>030- 037>040-043>046-053-054. WINTER STORM WARNING until 6 AM CST Friday FOR MOZ001>008- 011>017-020>025-031>033. KS...WINTER STORM WARNING until Midnight CST tonight FOR KSZ057-060- 103>105. WINTER STORM WARNING until 6 AM CST Friday FOR KSZ025-102. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
530 AM CST Thu Feb 21 2013 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... Intense winter storm is taking direct aim on the forecast area this morning. Overnight model runs...including the near-term RAP and HRRR models...now indicate a broad swath of 1"+ liquid-equivalent precipitation totals overspreading most of the forecast area with the heaviest axis centered very close to Kansas City. How these precip totals translate into snow and sleet amounts is still somewhat of a question mark given the presence of warm air in the 800-700 hPa layer and a shallow depth of the max dendritic growth region. Seems most methods are giving snow to liquid ratios on the order of 8:1 to 10:1 near I-70...and around 10:1 to 12:1 north of Highway 36. Applying these ratios to expected precip totals now results in a broad swath of 8 to 12 inch snows forecast for most of the forecast area...generally along and north of a Paola...Marshall...Moberly line. These areas are unlikely to see much if any sleet contamination and could see some totals approach or exceed February records (see climate section below). Still expect sleet to fall across areas south of this line, and there could be a good deal of it. Exactly how much sleet falls across these areas will have huge impacts on snow amounts, which could be as low as 3 or 4 inches if sleet lasts several hours...to as much as 8 to 10 inches if sleet is only brief. Freezing rain still appears a possibility for the Clinton/Sedalia/Boonville areas but any icing should be limited to a tenth of an inch or less. Looking upstream, synoptic and mesoscale ascent has become quite strong and is coupled throughout a large depth of the atmosphere. Combine this with strong moisture advection from the south, the result has been an expanding area of heavy precipitation over northern OK and southern KS with several bands of convection feeding into it. In fact, lightning profilers have lit up vividly down there, even in the stratiform precipitation over KS, suggestive of quite a bit of slantwise and even upright instability. This instability will spread into ern KS/wrn MO through the morning and could easily result in occasional thunder and snowfall rates of 2" to 3" per hour. Heaviest precipitation band will spread into northern MO through the afternoon and taper off across the KC area by 21Z or so. However, broad synoptic scale and weak deformation forcing will continue well into the evening and overnight as the upper low moves overhead. This could result in an extra 2" to 5" of snow from late afternoon into the early morning hours particularly north of the Missouri River. Hawblitzel Friday and Saturday... As the system departs, a few lingering snow showers may be possible across far northeast Missouri, but little to no additional snow accumulation is expected. Temperatures will have difficulty rising much on Friday with widespread snow cover and colder air advecting into the region, so have kept high temperatures only a few degrees warmer than Thursday night lows. Frigid temperatures are possible Friday night as surface high pressure drifts over western Missouri, combining the residual snow cover with light winds and clear skies. Warmer air will begin to build into the region on Saturday as the upper low departs, but reaching highs much above freezing will be difficult, especially without strong return flow at low levels. Sunday and Monday... Another deep trough axis will swing through the four corners region on Sunday, bringing a deepening surface low into the southern High Plains by early Monday. This system is currently projected to lift northeast into the region on Monday afternoon, taking a somewhat similar track to the current system; however, there is still a good deal of uncertainty in this forecast. Moisture may be a bit more limited with a smaller window of time to draw from the Gulf, and this more southern track is a very recent trend with the 00z models, so for now have kept probabilities relatively low and maintained a rain or snow precipitation type to cover several possible scenarios. Tuesday through Thursday... Quieter conditions should prevail for the remainder of next week as a more persistent ridge builds over the west. A few snow showers may be possible Tuesday night into early Wednesday as a weak clipper dives in behind the departing upper low, but any snowfall that does occur should be fairly light, and the probability of measurable snow is low. Temperatures will remain below normal as a result of cold air wrapping behind the upper low and additional cold air dropping southeast with the clipper, but should eventually recover when the ridge over the Rockies begins to shift east. Laflin && .CLIMATE... The last time Kansas City officially measured 12" of snow was January 18-19 in 1962 (14.0"). The most recent snowfall greater than 10" was February 24-25 in 1993 (11.1"). Top 10 snowfalls for Kansas City 1. 24.2"...Mar 22-24 1912 2. 15.8"...Feb 11-12 1894 3. 14.6"...Jan 20-21 1958 4. 14.0"...Jan 18-19 1962 5. 13.8"...Mar 14-15 1960 6. 13.7"...Jan 8-9 1930 7. 13.0"...Feb 27-28 1900 8. 12.3"...Mar 29-31 1926 9. 12.2"...Dec 23-24 1918 10. 11.9"...Mar 3-5 1915 Top 5 daily February snowfalls for Kansas City 1. 11.8"...27th 1900 2. 10.5"...4th 1915 3. 8.7"...23rd 1990 4. 8.6"...2nd 1960 5. 8.0"...15th 1960 && .AVIATION... For the 12Z TAFs...major winter storm will impact all terminals for much of the day with very heavy snow rates of 1 to 2 inches per hour, possibly more. Occasional lightning is also possible. This activity is right on the doorstep, so will go ahead and introduce heavy snow to the KC and STJ terminals right at the onset of the TAF period. The heavy nature of the snow is likely to bring every airport below operational minimums at times. Heaviest snow will gradually taper off across KC/STJ by mid afternoon, and across central and northeast MO late afternoon. However, additional light snow through the evening could produce additional light accumulations and prolonged IFR conditions through the night. Hawblitzel && .EAX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING until Midnight CST tonight FOR MOZ039-040- 045-046. WINTER STORM WARNING until Midnight CST tonight FOR MOZ028>030- 037-038-043-044-053-054. WINTER STORM WARNING until 6 AM CST Friday FOR MOZ001>004- 011>013-020-021. WINTER STORM WARNING until 6 AM CST Friday FOR MOZ005>008- 014>017-022>025-031>033. KS...WINTER STORM WARNING until Midnight CST tonight FOR KSZ057-060- 103>105. WINTER STORM WARNING until 6 AM CST Friday FOR KSZ025-102. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
353 AM CST Thu Feb 21 2013 .DISCUSSION... Intense winter storm is taking direct aim on the forecast area this morning. Overnight model runs...including the near-term RAP and HRRR models...now indicate a broad swath of 1"+ liquid-equivalent precipitation totals overspreading most of the forecast area with the heaviest axis centered very close to Kansas City. How these precip totals translate into snow and sleet amounts is still somewhat of a question mark given the presence of warm air in the 800-700 hPa layer and a shallow depth of the max dendritic growth region. Seems most methods are giving snow to liquid ratios on the order of 8:1 to 10:1 near I-70...and around 10:1 to 12:1 north of Highway 36. Applying these ratios to expected precip totals now results in a broad swath of 8 to 12 inch snows forecast for most of the forecast area...generally along and north of a Paola...Marshall...Moberly line. These areas are unlikely to see much if any sleet contamination and could see some totals approach or exceed February records (see climate section below). Still expect sleet to fall across areas south of this line, and there could be a good deal of it. Exactly how much sleet falls across these areas will have huge impacts on snow amounts, which could be as low as 3 or 4 inches if sleet lasts several hours...to as much as 8 to 10 inches if sleet is only brief. Freezing rain still appears a possibility for the Clinton/Sedalia/Boonville areas but any icing should be limited to a tenth of an inch or less. Looking upstream, synoptic and mesoscale ascent has become quite strong and is coupled throughout a large depth of the atmosphere. Combine this with strong moisture advection from the south, the result has been an expanding area of heavy precipitation over northern OK and southern KS with several bands of convection feeding into it. In fact, lightning profilers have lit up vividly down there, even in the stratiform precipitation over KS, suggestive of quite a bit of slantwise and even upright instability. This instability will spread into ern KS/wrn MO through the morning and could easily result in occasional thunder and snowfall rates of 2" to 3" per hour. Heaviest precipitation band will spread into northern MO through the afternoon and taper off across the KC area by 21Z or so. However, broad synoptic scale and weak deformation forcing will continue well into the evening and overnight as the upper low moves overhead. This could result in an extra 2" to 5" of snow from late afternoon into the early morning hours particularly north of the Missouri River. Hawblitzel Friday and Saturday... As the system departs, a few lingering snow showers may be possible across far northeast Missouri, but little to no additional snow accumulation is expected. Temperatures will have difficulty rising much on Friday with widespread snow cover and colder air advecting into the region, so have kept high temperatures only a few degrees warmer than Thursday night lows. Frigid temperatures are possible Friday night as surface high pressure drifts over western Missouri, combining the residual snow cover with light winds and clear skies. Warmer air will begin to build into the region on Saturday as the upper low departs, but reaching highs much above freezing will be difficult, especially without strong return flow at low levels. Sunday and Monday... Another deep trough axis will swing through the four corners region on Sunday, bringing a deepening surface low into the southern High Plains by early Monday. This system is currently projected to lift northeast into the region on Monday afternoon, taking a somewhat similar track to the current system; however, there is still a good deal of uncertainty in this forecast. Moisture may be a bit more limited with a smaller window of time to draw from the Gulf, and this more southern track is a very recent trend with the 00z models, so for now have kept probabilities relatively low and maintained a rain or snow precipitation type to cover several possible scenarios. Tuesday through Thursday... Quieter conditions should prevail for the remainder of next week as a more persistent ridge builds over the west. A few snow showers may be possible Tuesday night into early Wednesday as a weak clipper dives in behind the departing upper low, but any snowfall that does occur should be fairly light, and the probability of measurable snow is low. Temperatures will remain below normal as a result of cold air wrapping behind the upper low and additional cold air dropping southeast with the clipper, but should eventually recover when the ridge over the Rockies begins to shift east. Laflin && .CLIMATE... The last time Kansas City officially measured 12" of snow was January 18-19 in 1962 (14.0"). The most snowfall greater than 10" was February 24-25 in 1993 (11.1"). Top 10 snowfalls for Kansas City 1. 24.2"...Mar 22-24 1912 2. 15.8"...Feb 11-12 1894 3. 14.6"...Jan 20-21 1958 4. 14.0"...Jan 18-19 1962 5. 13.8"...Mar 14-15 1960 6. 13.7"...Jan 8-9 1930 7. 13.0"...Feb 27-28 1900 8. 12.3"...Mar 29-31 1926 9. 12.2"...Dec 23-24 1918 10. 11.9"...Mar 3-5 1915 Top 5 daily February snowfalls for Kansas City 1. 11.8"...27th 1900 2. 10.5"...4th 1915 3. 8.7"...23rd 1990 4. 8.6"...2nd 1960 5. 8.0"...15th 1960 && .AVIATION... For the 06Z TAFs...Thinks look to be on track for the winter storm system that will affect the terminals beginning this morning. Overnight conditions will remain VFR with a cloud deck between 6-7kft. Light returns showing up on radar will remain as virga as the air in the lower 6kft will be very dry. By 14Z-15Z this dry air will be overcome and cigs will quick drop into the MVFR category with vsbys dropping 5SM with the onset of light snow. There will be a period of moderate to occasionally heavy snow at the terminals between 17Z-21Z at which point snow rates could be as high 2-3" inches per hour thus making it difficult for snow removal on runways. The heavy snow will also be accompanied by IFR and occasional VLIFR cigs/vis with even the potential for thundersnow which may be added to the TAF forecast as we get closer to the event. Moderate snow is then expected to continue with IFR cigs/vis through 23Z. Snow should begin to taper off becoming light by 23Z however IFR cigs with vsbys improving to 1SM will continue through the end of the TAF period. Winds overnight will be between 10-15kts but will pick up tomorrow morning as the pressure gradient tightens across the area. Winds tomorrow will be between 15-20kts with gusts to 25-30kts however blowing snow is not expected to be a concern due to the heavy nature of the snow. Winds will weaken somewhat by tomorrow evening but still remain between 10-15kts with gusts to 25kts while backing to the east-northeast. 73 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING until Midnight CST tonight FOR MOZ039-040- 045-046. WINTER STORM WARNING until Midnight CST tonight FOR MOZ028>030- 037-038-043-044-053-054. WINTER STORM WARNING until 6 AM CST Friday FOR MOZ001>004- 011>013-020-021. WINTER STORM WARNING until 6 AM CST Friday FOR MOZ005>008- 014>017-022>025-031>033. KS...WINTER STORM WARNING until Midnight CST tonight FOR KSZ057-060- 103>105. WINTER STORM WARNING until 6 AM CST Friday FOR KSZ025-102. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1011 PM CST WED FEB 20 2013 .UPDATE... ISSUED AT 928 PM CST WED FEB 20 2013 NOT A WHOLE LOT OF CHANGES TO THE FORECAST FOR TONIGHT ASIDE FROM INCREASING SNOWFALL AMOUNTS IN OUR SOUTHWEST ZONES WHERE A 9 INCH AMOUNT HAS BEEN RECEIVED IN PLAINVILLE KS IN ROOKS COUNTY. FARTHER EAST...THE DRIER AIR HAS BEEN SLOW TO OVERCOME AND HAVE LOWERED SNOWFALL AMOUNTS SLIGHTLY FOR OUR EAST/NORTHEAST ZONES. SNOW HAS BEGUN TO INCREASE IN COVERAGE ACROSS OUR SOUTHWEST CWA AND THE SNOW WILL SPREAD NORTH OVERNIGHT. OUR EASTERN AREAS COULD STILL PICK UP AN INCH OR TWO PRIOR TO DAYBREAK...ALTHOUGH THE HIGHER AMOUNTS WILL STILL BE REALIZED ACROSS SOUTHERN/WESTERN AREAS. THE 00Z RUN OF THE NAM REMAINS CONSISTENT WITH THE UPPER LOW LIFTING NORTHEAST FM THE TX PANHANDLE THURSDAY MORNING INTO EAST CENTRAL KS BY 00Z FRIDAY. DEFORMATION SNOWFALL WILL DEVELOP ACROSS KS EARLY THURSDAY AND SPREAD NORTHWARD AS SYSTEMS LIFTS NORTHEAST DURING THE DAY. WE ARE STILL LOOKING AT WIDESPREAD HEAVY SNOWFALL DEVELOPING IN KS THURSDAY MORNING AND SPREADING INTO NEBRASKA BY THURSDAY AFTN AND CONTINUING INTO THE EVENING. 00Z NAM STORM TOTAL SNOWFALL REMAINS CONSISTENT WITH PREVIOUS RUNS AND OTHER MODELS WITH POTENTIAL OF 10 INCHES OR MORE OF SNOW...WITH WELL OVER A FOOT POSSIBLE ACROSS NC KS INTO SW/SC NEB. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 239 PM CST WED FEB 20 2013 TONIGHT THROUGH EARLY FRIDAY MORNING...FOCUS CONTINUES TO BE ON THE APPROACHING UPPER LEVEL DISTURBANCE CURRENTLY VISIBLE IN WATER VAPOR IMAGERY CIRCULATING ACROSS CENTRAL ARIZONA. MOISTURE AHEAD OF THIS DISTURBANCE HAS BEEN SURGING NORTHWARD FOR MUCH OF THE DAY TODAY...WITH LIGHT SNOW SLOWLY SPREADING NORTHWARD INTO PORTIONS OF SOUTH CENTRAL NEBRASKA THE PAST FEW HOURS. EXPECT THIS LIGHT SNOW TO CONTINUE THROUGH THE EVENING HOURS...AND INTENSIFY SOME OVERNIGHT. WITH THE OVERALL SLOWER AND MORE SOUTHEASTWARD TRACK OF THIS SYSTEM...NOW EXPECT THE HEAVIEST SNOWFALL TO DEVELOP IN BANDS ACROSS NORTH CENTRAL KANSAS DURING THE EARLY MORNING HOURS THURSDAY...WORKING ITS WAY INTO SOUTH CENTRAL NEBRASKA BY MID MORNING. THAT SAID...STILL EXPECT SOME SNOWFALL ACCUMULATIONS THIS AFTERNOON AND EVENING...ESPECIALLY ACROSS THE SOUTHWESTERN SECTIONS OF THE FORECAST AREA...WITH LIGHT SNOWFALL POSSIBLY NOT WORKING INTO THE EASTERN FRINGES OF THE LOCAL AREA UNTIL ABOUT MIDNIGHT. LATEST RAP CONTINUES TO BE THE MAIN OUTLIER HOLDING OFF WIDESPREAD SNOW UNTIL AROUND DAYBREAK THURSDAY FOR MUCH OF THE EASTERN HALF OF THE FORECAST AREA...DUE TO ITS DEPICTION OF A MORE SIGNIFICANT DRY LAYER NEAR THE GROUND IN THE LOW LEVEL EASTERLY FLOW. HOWEVER...WITH THE NAM/SREF/GFS/EC/WRF ALL DEVELOPING MORE WIDESPREAD PRECIPITATION BEFORE THEN...MOSTLY DISCOUNTED RAP ANALYSIS...AND KEPT ONSET OF PRECIPITATION SIMILAR TO THIS MORNINGS FORECAST. OTHERWISE...WHILE THE OVERALL TIMING OF THE MAIN SYSTEM ACROSS THE DESERT SOUTHWEST HAS SLOWED DOWN A BIT IN THE 12Z MODELS...IT STILL LOOKS TO BE A MAJOR WINTER STORM EVENT...AND HAVE ADJUSTED FOR THE SLOWER ANALYSIS BY EXTENDING THE WINTER STORM WARNING FOR THE NORTH/NORTHEASTERN HALF OF THE AREA BY 6 HOURS. AND WHILE OVERALL LIQUID EQUIVALENTS HAVE COME DOWN TO AROUND AN INCH FOR THE TRI CITIES AREA WITH THIS SYSTEM...RANGING FROM AROUND 0.75 IN THE EC TO AROUND 1.2 IN THE NAM...INCREASED SNOWFALL RATIOS TO BE SLIGHTLY HIGHER THAN PREVIOUSLY THOUGHT IN THIS COLD AIRMASS...SO ONLY VERY MINOR TWEAKS ARE EVIDENT IN THE OVERALL SNOWFALL ACCUMULATIONS. IN ADDITION TO SNOWFALL...EXPECT BREEZY SOUTHEASTERLY WINDS TO CONTINUE THROUGH THE EVENING AND OVERNIGHT HOURS...AS THE PRESSURE GRADIENT BEGINS TO TIGHTEN AHEAD OF THE APPROACHING SURFACE LOW. WINDS ARE THEN EXPECTED TO EVENTUALLY RELAX AND SHIFT MORE NORTHERLY ON THE BACKSIDE OF THE SURFACE LOW AS IT CROSSES INTO MISSOURI AND IOWA BY TOMORROW EVENING. HOWEVER...WITH LOTS OF FAIRLY DRY SNOW AND BREEZY WINDS...VISIBILITIES ARE EXPECTED TO BE REDUCED IN AREAS OF BLOWING SNOW THROUGH THE DURATION OF THIS EVENT...NOT IMPROVING TIL AFTER 00Z...AND KEPT AREAS OF BLOWING SNOW IN THE FORECAST AS A CONSEQUENCE. TEMPERATURES THROUGH THIS EVENT ARE EXPECTED TO REMAIN ON THE COLD SIDE OF CLIMATOLOGY FOR MID FEBRUARY...WITH AFTERNOON HIGHS ON THURSDAY LIKELY NOT RISING MUCH ABOVE THE MORNING LOWS AS THE CLOUD COVER AND SNOW WILL PUT A CAP ON HEATING ACROSS THE LOCAL AREA. TEMPERATURES ARE THEN EXPECTED TO PLUMMET FRIDAY MORNING ON THE BACKSIDE OF THIS SYSTEM...AS SOME CLEARING ALONG WITH RELAXING WINDS AND FRESH SNOW COVER SHOULD ALLOW FOR GOOD RADIATIONAL COOLING BY EARLY FRIDAY MORNING. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 239 PM CST WED FEB 20 2013 PATTERN: THIS IS A STORMY PATTERN AND EXCITING IF YOU/RE A WINTER WX FAN. WE ARE LIKELY TO SEE WINTERS FURY CONTINUE FULL BORE THRU THE END OF THE MONTH. THIS MEANS AT LEAST ONE MORE SNOW/WIND STORM AND COLDER THAN NORMAL DAYTIME TEMPS...WITH SEVERAL DAYS OF MUCH BELOW NORMAL /ANYTHING 33F OR BELOW/. THE -PNA/-NAO IS DICTATING THE LONG-WAVE PATTERN WHICH FEATURES A STORMY WRN USA TROF AND INCREASING DOWNSTREAM BLOCKING OVER ERN N AMERICA. FOR THOSE NOT EXCITED ABOUT WINTER WX...THE PNA WILL REACH ITS LOWEST POINT THIS WEEK AND THEN TURN POSITIVE THE 1ST WEEK OF MAR. THE ANOMALOUS E PAC RIDGE /+2 STANDARD DEVIATION HGTS/ WILL TAKE A BIG HIT NEXT MON-TUE FROM A DEEPENING GULF OF AK STORM. THIS WILL INITIATE THE RETROGRESSION AND REPOSITION THE LONG-WAVE TROF FURTHER W...INDUCING A RIDGE OVER THE WRN USA NEXT WED. HAZARDS: THERE IS POTENTIAL FOR ANOTHER WINTER STORM SUN NGT-MON WITH APPRECIABLE AMOUNTS OF SNOW POSSIBLE. UPCOMING PCPN OPPORTUNITIES: 2/25. FRI THE STORM CONTINUES TO EXIT. ANOTHER PIECE OF ENERGY MOVES THRU SAT...ON THE BACKSIDE OF THE TROF. THE NEXT POTENT TROF DIVES INTO THE INTERMOUNTAIN W IN THE MEANTIME...AND DEEPENS SUN-MON AS WAVELENGTH DECREASES. ANOTHER VORT MAX FOLLOWS INTO THE DESERT SW TUE AND THIS ODDS FAVOR THIS STORM BEING SUPPRESSED FAR TO OUR S. THE DAILY DETAILS... CONFIDENCE IS BELOW AVERAGE ON OUR DAYTIME HIGHS THRU THE PERIOD SINCE MODELS STRUGGLE WITH SUBSTANTIAL SNOW-PACK ON THE GROUND. WE MAY NOT BE COLD ENOUGH. FRI: CLEAN-UP AND RECOVERY BUT VERY COLD WITH PLENTY OF CLOUDS. ANY BREAKS THAT DEVELOP WILL FILL BACK IN UNDER THERMAL TROF. CANT COMPLETELY RULE OUT A STRAY AFTN FLURRY. WINDS NOT BAD. SAT: QUIET INTERLUDE. CONFIDENCE IS AVERAGE. WOULDNT RULE OUT SOME FLURRIES...BUT LOW-LEVEL MSTR APPEARS LIMITED. SAT NGT: MAINTAINED CONTINUITY WITH PREVIOUS FCST FOR A SLGT CHANCE OF FRZG DRZL...BUT WITH LOW CONFIDENCE. INCREASING LOW-LEVEL MSTR OVER A COLD SNOW PACK COULD RESULT IN STRATUS. DID REMOVE FLURRIES FROM THE FCST. LOW-LEVEL THERMAL PROFILES MAY NOT BE COLD ENOUGH FOR SNOW GRAINS. SUN: BACKED DOWN POPS TO SLGT CHANCE. SUN NGT-MON: THIS STORM COULD BE TROUBLE. COORDINATED WITH HPC AT 1530Z. BELIEVE THIS STORM TAKES A VERY SIMILAR TRACK TO THE CURRENT STORM. THE DIFF IS THIS STORM IS WE/RE GETTING A SIGNAL THAT IT LINGERS OR STALLS OVER ERN KS DURING THE DAYLIGHT HRS MON...BEFORE SLOWLY HEADING TOWARD THE GREAT LAKES MON NGT-TUE. ACCUMULATING/PLOWABLE SNOW REQUIRING WATCHES/WARNINGS/ADVISORIES APPEARS LIKELY BASED ON TRENDS IN THE LAST 72 HRS. BUT THIS DOES NOT NECESSARILY MEAN FOR OUR ENTIRE FCST AREA. POPS HAVE BEEN INCREASED TO 60-70%. THINK WE NEED TO PREPARE FOR THE OPTION OF A SLOW-MOVING...POSSIBLY LONG-LIVED STORM. THE BLOCKING HIGH DOWNSTREAM URGES CAUTION. THIS STORM HAS POTENTIAL TO BE VERY WINDY. MODELS: 1456Z PMDEPD AND HPC GUIDANCE REVIEWED AND WE ARE IN AGREEMENT ON A SLOWER SOLUTION PER THE EC/GEM ENSEMBLES. MOST GFS ENSEMBLE MEMBERS LOOK TOO FAST/PROGRESSIVE AS EARLY AS 12Z/SUN. EVEN THE HIGHER RES OPERATIONAL GFS RUNS ARE TOWARD THE SLOWER PACK. TUE: CYCLONIC FLOW GRADUALLY RELEASES BUT STILL EXPECT PLENTY OF CLOUDS THRU MIDDAY UNDER THERMAL TROF. BEST IMPROVEMENT S AND W OF TRI-CITIES. WED: QUIET AND DRY. NAO/PNA TELECONNECTIONS: THESE REFER TO THE NORTH ATLANTIC OSCILLATION AND PACIFIC-NORTH AMERICAN OSCILLATION. THESE OSCILLATIONS DEAL WITH RIDGES/TROFS AND PATTERNS IN THE JET STREAM. THE VARIOUS CONFIGURATIONS DICTATE WHAT OUR SENSIBLE WEATHER WILL BE...ABOVE OR BELOW NORMAL TEMPS...AND DRIER OR WETTER THAN NORMAL. -PNA: THIS IS A TROF OVER THE WRN USA. COLDER AND STORMIER FOR THE CNTRL PLAINS. +PNA: THIS IS A RIDGE OVER THE WRN USA. THIS IS A QUIET AND MILD PATTERN HERE. THE NAO IS MOSTLY A PLAYER IN OUR STORM TRACKS HERE ON THE PLAINS. +NAO: NO BLOCKING IN THE ATMOSPHERE NEAR GREENLAND. AT TIMES... THIS ALLOWS COLORADO LOWS TO TRACK MORE ACROSS NEB. -NAO: BLOCKING NEAR GREENLAND. THIS TENDS TO FORCE COLORADO LOWS TO OUR S...ACROSS KS. THIS WEBSITE HAS ADDITIONAL INFO...SOME OF WHICH IS TECHNICAL. CHECK OUT THE MAPS THAT INDICATE INDICATE THE POSITIVE PHASES. WARM COLORS INDICATE WARMER TEMPS AND DECREASED STORMINESS. COLD COLORS INDICATE COLDER TEMPS AND INCREASED STORMINESS. FOR THE NEGATIVE PHASES...JUST REVERSE THE COLORS. THESE TELECONNECTIONS HAVE THE GREATEST IMPACTS IN THE COOLER MONTHS OF THE YEAR. WWW.CPC.NCEP.NOAA.GOV/DATA/TELEDOC/TELEINTRO.SHTML (ALL LOWER CASE) && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1005 PM CST WED FEB 20 2013 SNOW WILL CONTINUE TO FALL INTERMITTENTLY THROUGH THE NIGHT WITH THE HEAVIEST SNOWFALL EXPECTED FROM MIDDAY THURSDAY THROUGH THE AFTERNOON AND EVENING AS A POTENT WINTER STORM SYSTEM CROSSES THE CENTRAL PLAINS. STEADY EASTERLY WINDS OVERNIGHT WILL TRANSITION NORTHEAST AND NORTHERLY THURS AFTN AND EVENING. CIGS AND VSBYS WILL BE DEPENDENT ON TIMING OF SNOW BANDS WITH LIFR CONDITONS LIKELY THURS AFTN/EVE. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WINTER STORM WARNING UNTIL MIDNIGHT CST THURSDAY NIGHT FOR NEZ039>041-046>049-060>064-072>077-085>087. WINTER STORM WARNING UNTIL 6 PM CST THURSDAY FOR NEZ082>084. KS...WINTER STORM WARNING UNTIL 6 PM CST THURSDAY FOR KSZ005>007- 017>019. && $$ UPDATE...FAY SHORT TERM...ROSSI LONG TERM...HALBLAUB AVIATION...FAY
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
457 PM MST FRI FEB 22 2013 .AVIATION... 00Z TAF CYCLE UPPER DISTURBANCE PASSING OVER NORTH CENTRAL/NORTHEAST NEW MEXICO BEFORE 23/12Z AND WILL BE ACCOMPANIED BY A COLD FRONT. SCT MAINLY MVFR CIGS/VBSYS IN SHSN WILL OCCASIONALLY OBSCURE MTS MAINLY ESPECIALLY ALONG AND NORTH OF INTERSTATE 40. SOME CLEARING ANTICIPATE AFTER 23/15Z WITH WINDS ALOFT BECOMING WLY AND SFC LEE TROUGH DEVELOPING AFT 23/18Z. && .PREV DISCUSSION...324 PM MST FRI FEB 22 2013... ANOTHER WEAK UPPER WAVE SLIDING ACROSS NORTHERN NM IN FAST NNW FLOW WILL KEEP THE SNOW MACHINE GOING OVER THE HIGH TERRAIN THROUGH EARLY SATURDAY. LOCAL HI RES WRF...NAM12...AND HRRR SOLUTIONS SHOW MESOSCALE FEATURES WITHIN THE LARGER SCALE REGIME SLIDING SOUTHWARD OUT OF THE NORTHERN MTS TONIGHT INTO THE RIO GRANDE VALLEY FROM SANTA FE TO THE ABQ METRO AREA THIS EVENING. INCREASED POPS ACCORDINGLY AND PLACED A DUSTING TO 1 INCH FOR THESE AREAS. FOR THE HIGH TERRAIN THERE HAS BEEN AN EBB AND FLOW OF LIGHT TO MODERATE SNOW AND SNOW SHOWERS SINCE THURSDAY MORNING WITH 1-4 INCHES OF SNOW EACH 12HR PERIOD ADDING UP TO SOME MODEST ACCUMULATIONS. TONIGHT WILL FEATURE ANOTHER 1-4 INCHES ABOVE 7500 FEET. A DISTINCT BREAK WILL TAKE SHAPE FOR THE ENTIRE AREA SATURDAY BEHIND TONIGHTS UPPER WAVE. A HIGHER IMPACT STORM WILL MOVE OVER NORTHERN NM SATURDAY NIGHT AND SUNDAY. THIS SYSTEM WILL BRING WITH IT A STRONG PACIFIC COLD FRONT AND ANOTHER ROUND OF WIND AND SNOW. THE NORTHERN MTS WILL SEE AN ADDITIONAL SEVERAL INCHES OF SNOW BUT WITH MORE WIND AND COLDER TEMPS THAN THE PAST 36 HRS SO SOME WINTER HIGHLIGHTS ARE EXPECTED. THE NE PLAINS WILL BE IN THE ACTION AS WELL WITH A TROWAL FEATURE SLIDING OVER THE AREA AS THE STORM SYSTEM DEEPENS OVER THE PLAINS STATES. TEMPS WILL DIVE BACK 10 TO 20F BLW NORMAL ONCE AGAIN. CONFIDENCE IS NOT HIGH ENOUGH FOR A WINTER STORM WATCH AT THIS TIME BUT IF MODEL TRENDS CONTINUE TO STRENGTHEN THAT COULD CHANGE. COLD TEMPS WILL CONTINUE INTO MONDAY AND TUESDAY WITH BREEZY TO LOCALLY WINDY CONDITIONS EXPECTED. BY LATE TUESDAY GUIDANCE SHOWS ANOTHER WAVE SLIDING SE OVER THE AREA WITH MORE SNOWFALL ACCUMS FOR THE NORTHERN HIGH TERRAIN. ANOTHER BREAK IS ON TAP WEDNESDAY BEFORE ANOTHER FAST MOVING SHEARED WAVE SLIDES OVER THURSDAY. BY THE END OF THE WEEK GUIDANCE FINALLY STOPS THE WAVE TRAIN AND SLOWLY PUSHES A RIDGE TOWARD THE AREA WITH SLIGHTLY WARMER TEMPS. GUYER && .FIRE WEATHER... AN UPPER LEVEL TROUGH WILL MOVE RAPIDLY TO THE EAST ACROSS NORTHERN NM TONIGHT PRODUCING LIGHT TO MODERATE SNOWFALL IN THE HIGHER TERRAIN AND ISOLATED AREAS OF LIGHT SNOW IN THE LOWER ELEVATIONS. MOIST NORTHWEST TO WEST FLOW ACROSS NORTHERN AND CENTRAL NM TONIGHT WILL KEEP RELATIVE HUMIDITIES ABOVE NORMAL THROUGH SATURDAY MORNING. INCREASING 700 MB WINDS AND THE FORMATION OF WEAK SURFACE LOW PRESSURE IN EASTERN NM ON SATURDAY WILL RESULT IN WEST WIND GUSTS UP TO 35 MPH EAST OF THE CENTRAL MOUNTAINS ALONG AND SOUTH OF I-40. MINIMUM RELATIVE HUMIDITY IN THESE AREAS WILL GENERALLY BE IN THE 17-25 PERCENT RANGE...SO THE RISK OF CRITICAL FIRE WEATHER CONDITIONS DEVELOPING SATURDAY AFTERNOON APPEARS LOW. VENTILATION SATURDAY WILL BE FAIR TO GOOD WEST OF THE CONTINENTAL DIVIDE AND GOOD TO VERY GOOD EAST OF THE DIVIDE. A SIGNIFICANTLY STRONGER AND COLDER UPPER LEVEL LOW WILL MOVE FROM THE EASTERN GREAT BASIN ACROSS NORTHERN AND CENTRAL NM SATURDAY NIGHT THROUGH SUNDAY AND THEN EXIT ACROSS NORTHEASTERN NM SUNDAY NIGHT. THE TRACK OF THIS SYSTEM HAS BEEN PROGRESSIVELY FURTHER TO THE SOUTH ON MODEL RUNS OVER THE PAST 48 HOURS. THIS TRACK WILL GENERATE THE STRONGEST WINDS ACROSS SOUTHERN NM ON SUNDAY. THE DRIEST LOW LEVEL AIR AND STRONGEST WINDS WILL LIKELY STAY TO THE SOUTH OF THE FIRE DISTRICT. WINDS WILL STILL BE MODERATE SUNDAY WITH GUSTS BETWEEN 30 TO 35 MPH ACROSS CENTRAL NM...ESPECIALLY SOUTH OF I-40. MOISTURE ACCOMPANYING THIS UPPER LEVEL TROUGH WILL KEEP DAYTIME RELATIVE HUMIDITY VALUES NEAR OR ABOVE 20 PERCENT...SO CRITICAL FIRE WEATHER CONDITIONS WILL BE UNLIKELY. SUSTAINED NORTHWEST WINDS SUNDAY WILL RANGE FROM 10 TO 25 MPH....RESULTING IN VERY GOOD TO EXCELLENT VENTILATION. AS THE UPPER LOW MOVES EASTWARD ACROSS WESTERN OK SUNDAY NIGHT...WRAP-AROUND MOISTURE WILL KEEP RELATIVE HUMIDITY HIGH ACROSS EASTERN NM....WHILE DECREASING WIND SPEEDS AND RESIDUAL LOW LEVEL MOISTURE ACROSS CENTRAL AND WESTERN NM WILL ALLOW FOR STRONG RELATIVE HUMIDITY RECOVERIES SUNDAY NIGHT THROUGH MONDAY MORNING. HIGH PRESSURE WILL BUILD ACROSS NM FROM THE WEST ON MONDAY WITH LIGHTER WINDS AND DRIER LOW LEVEL AIR MOVING INTO THE REGION. AFTERNOON WINDS IN THE EASTERN PLAINS WILL CREATE FAIR TO GOOD VENTILATION...BUT LIGHTER WINDS ACROSS THE REMAINDER OF NM WILL CREATE ONLY POOR TO FAIR VENTILATION. ANOTHER UPPER LEVEL TROUGH MAY AFFECT NORTHERN AND CENTRAL NM ON TUESDAY...MOST LIKELY IN THE AFTERNOON TO EVENING HOURS...THOUGH MODEL GUIDANCE STILL VARIES ON TIMING. THIS SYSTEM WOULD MOST LIKELY BRING SNOW TO NORTHERN NM...BUT CENTRAL NM COULD RECEIVE SNOW GIVEN A SLIGHT ADJUSTMENT IN THE TRACK OF THE STORM. THIS TROUGH WILL MOST LIKELY KEEP TEMPERATURES BELOW NORMAL AND RELATIVE HUMIDITY ABOVE NORMAL THROUGH MIDWEEK. WEAK HIGH PRESSURE WILL DRIFT ACROSS NM WEDNESDAY WITH A GREATER POSSIBILITY FOR STRONGER MORNING INVERSIONS AND POORER DAYTIME VENTILATION. 28 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
324 PM MST FRI FEB 22 2013 .DISCUSSION... ANOTHER WEAK UPPER WAVE SLIDING ACROSS NORTHERN NM IN FAST NNW FLOW WILL KEEP THE SNOW MACHINE GOING OVER THE HIGH TERRAIN THROUGH EARLY SATURDAY. LOCAL HI RES WRF...NAM12...AND HRRR SOLUTIONS SHOW MESOSCALE FEATURES WITHIN THE LARGER SCALE REGIME SLIDING SOUTHWARD OUT OF THE NORTHERN MTS TONIGHT INTO THE RIO GRANDE VALLEY FROM SANTA FE TO THE ABQ METRO AREA THIS EVENING. INCREASED POPS ACCORDINGLY AND PLACED A DUSTING TO 1 INCH FOR THESE AREAS. FOR THE HIGH TERRAIN THERE HAS BEEN AN EBB AND FLOW OF LIGHT TO MODERATE SNOW AND SNOW SHOWERS SINCE THURSDAY MORNING WITH 1-4 INCHES OF SNOW EACH 12HR PERIOD ADDING UP TO SOME MODEST ACCUMULATIONS. TONIGHT WILL FEATURE ANOTHER 1-4 INCHES ABOVE 7500 FEET. A DISTINCT BREAK WILL TAKE SHAPE FOR THE ENTIRE AREA SATURDAY BEHIND TONIGHTS UPPER WAVE. A HIGHER IMPACT STORM WILL MOVE OVER NORTHERN NM SATURDAY NIGHT AND SUNDAY. THIS SYSTEM WILL BRING WITH IT A STRONG PACIFIC COLD FRONT AND ANOTHER ROUND OF WIND AND SNOW. THE NORTHERN MTS WILL SEE AN ADDITIONAL SEVERAL INCHES OF SNOW BUT WITH MORE WIND AND COLDER TEMPS THAN THE PAST 36 HRS SO SOME WINTER HIGHLIGHTS ARE EXPECTED. THE NE PLAINS WILL BE IN THE ACTION AS WELL WITH A TROWAL FEATURE SLIDING OVER THE AREA AS THE STORM SYSTEM DEEPENS OVER THE PLAINS STATES. TEMPS WILL DIVE BACK 10 TO 20F BLW NORMAL ONCE AGAIN. CONFIDENCE IS NOT HIGH ENOUGH FOR A WINTER STORM WATCH AT THIS TIME BUT IF MODEL TRENDS CONTINUE TO STRENGTHEN THAT COULD CHANGE. COLD TEMPS WILL CONTINUE INTO MONDAY AND TUESDAY WITH BREEZY TO LOCALLY WINDY CONDITIONS EXPECTED. BY LATE TUESDAY GUIDANCE SHOWS ANOTHER WAVE SLIDING SE OVER THE AREA WITH MORE SNOWFALL ACCUMS FOR THE NORTHERN HIGH TERRAIN. ANOTHER BREAK IS ON TAP WEDNESDAY BEFORE ANOTHER FAST MOVING SHEARED WAVE SLIDES OVER THURSDAY. BY THE END OF THE WEEK GUIDANCE FINALLY STOPS THE WAVE TRAIN AND SLOWLY PUSHES A RIDGE TOWARD THE AREA WITH SLIGHTLY WARMER TEMPS. GUYER && .FIRE WEATHER... AN UPPER LEVEL TROUGH WILL MOVE RAPIDLY TO THE EAST ACROSS NORTHERN NM TONIGHT PRODUCING LIGHT TO MODERATE SNOWFALL IN THE HIGHER TERRAIN AND ISOLATED AREAS OF LIGHT SNOW IN THE LOWER ELEVATIONS. MOIST NORTHWEST TO WEST FLOW ACROSS NORTHERN AND CENTRAL NM TONIGHT WILL KEEP RELATIVE HUMIDITIES ABOVE NORMAL THROUGH SATURDAY MORNING. INCREASING 700 MB WINDS AND THE FORMATION OF WEAK SURFACE LOW PRESSURE IN EASTERN NM ON SATURDAY WILL RESULT IN WEST WIND GUSTS UP TO 35 MPH EAST OF THE CENTRAL MOUNTAINS ALONG AND SOUTH OF I-40. MINIMUM RELATIVE HUMIDITY IN THESE AREAS WILL GENERALLY BE IN THE 17-25 PERCENT RANGE...SO THE RISK OF CRITICAL FIRE WEATHER CONDITIONS DEVELOPING SATURDAY AFTERNOON APPEARS LOW. VENTILATION SATURDAY WILL BE FAIR TO GOOD WEST OF THE CONTINENTAL DIVIDE AND GOOD TO VERY GOOD EAST OF THE DIVIDE. A SIGNIFICANTLY STRONGER AND COLDER UPPER LEVEL LOW WILL MOVE FROM THE EASTERN GREAT BASIN ACROSS NORTHERN AND CENTRAL NM SATURDAY NIGHT THROUGH SUNDAY AND THEN EXIT ACROSS NORTHEASTERN NM SUNDAY NIGHT. THE TRACK OF THIS SYSTEM HAS BEEN PROGRESSIVELY FURTHER TO THE SOUTH ON MODEL RUNS OVER THE PAST 48 HOURS. THIS TRACK WILL GENERATE THE STRONGEST WINDS ACROSS SOUTHERN NM ON SUNDAY. THE DRIEST LOW LEVEL AIR AND STRONGEST WINDS WILL LIKELY STAY TO THE SOUTH OF THE FIRE DISTRICT. WINDS WILL STILL BE MODERATE SUNDAY WITH GUSTS BETWEEN 30 TO 35 MPH ACROSS CENTRAL NM...ESPECIALLY SOUTH OF I-40. MOISTURE ACCOMPANYING THIS UPPER LEVEL TROUGH WILL KEEP DAYTIME RELATIVE HUMIDITY VALUES NEAR OR ABOVE 20 PERCENT...SO CRITICAL FIRE WEATHER CONDITIONS WILL BE UNLIKELY. SUSTAINED NORTHWEST WINDS SUNDAY WILL RANGE FROM 10 TO 25 MPH....RESULTING IN VERY GOOD TO EXCELLENT VENTILATION. AS THE UPPER LOW MOVES EASTWARD ACROSS WESTERN OK SUNDAY NIGHT...WRAP-AROUND MOISTURE WILL KEEP RELATIVE HUMIDITY HIGH ACROSS EASTERN NM....WHILE DECREASING WIND SPEEDS AND RESIDUAL LOW LEVEL MOISTURE ACROSS CENTRAL AND WESTERN NM WILL ALLOW FOR STRONG RELATIVE HUMIDITY RECOVERIES SUNDAY NIGHT THROUGH MONDAY MORNING. HIGH PRESSURE WILL BUILD ACROSS NM FROM THE WEST ON MONDAY WITH LIGHTER WINDS AND DRIER LOW LEVEL AIR MOVING INTO THE REGION. AFTERNOON WINDS IN THE EASTERN PLAINS WILL CREATE FAIR TO GOOD VENTILATION...BUT LIGHTER WINDS ACROSS THE REMAINDER OF NM WILL CREATE ONLY POOR TO FAIR VENTILATION. ANOTHER UPPER LEVEL TROUGH MAY AFFECT NORTHERN AND CENTRAL NM ON TUESDAY...MOST LIKELY IN THE AFTERNOON TO EVENING HOURS...THOUGH MODEL GUIDANCE STILL VARIES ON TIMING. THIS SYSTEM WOULD MOST LIKELY BRING SNOW TO NORTHERN NM...BUT CENTRAL NM COULD RECEIVE SNOW GIVEN A SLIGHT ADJUSTMENT IN THE TRACK OF THE STORM. THIS TROUGH WILL MOST LIKELY KEEP TEMPERATURES BELOW NORMAL AND RELATIVE HUMIDITY ABOVE NORMAL THROUGH MIDWEEK. WEAK HIGH PRESSURE WILL DRIFT ACROSS NM WEDNESDAY WITH A GREATER POSSIBILITY FOR STRONGER MORNING INVERSIONS AND POORER DAYTIME VENTILATION. 28 && .AVIATION... 18Z TAF CYCLE WEAK UPPER LEVEL TROUGH OVER SOUTHWEST CO THIS MORNING WILL MOVE SOUTHEAST ACROSS NORTHERN NM LATE THIS AFTERNOON THROUGH THE EARLY MORNING HOURS ON SATURDAY. WHILE THIS SYSTEM IS EXPECTED TO PRODUCE ISOLATED LIGHT SNOW SHOWERS AND MOUNTAIN OBSCURATIONS ACROSS THE HIGHER TERRAIN OF NORTHERN NM THROUGH MIDNIGHT...VFR CLOUD DECKS ARE EXPECTED ACROSS THE LOWER ELEVATIONS AND AT THE TAF SITES. THE 12Z RUN OF THE NAM MODEL CONTINUES TO SHOW A BAND OF SNOW FORMING ACROSS THE MIDDLE RIO GRANDE VALLEY AFTER 00Z TONIGHT. CONFIDENCE IN THE FORMATION OF THE SNOW BAND IS NOT HIGH HOWEVER... SO INCLUDED TEMPO FOR LIGHT SNOW AT KABQ FROM 01Z TO 04Z. AFTER THIS LOW PRESSURE SYSTEM MOVES EASTWARD INTO WESTERN TX...WEST WINDS LESS THAN 10 KTS ARE EXPECTED ACROSS MOST OF THE REGION. HOWEVER... WINDS IN THE FAR EASTERN PLAINS...INCLUDING KTCC...WILL SHIFT FROM THE EAST TO THE NORTHEAST TONIGHT...AS LOW PRESSURE PASSES TO THE NORTH. 28 && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 19 45 19 35 / 10 5 40 20 DULCE........................... 6 37 11 29 / 30 5 50 30 CUBA............................ 10 42 15 29 / 40 0 40 40 GALLUP.......................... 21 48 20 32 / 10 0 40 20 EL MORRO........................ 10 39 15 27 / 20 0 30 30 GRANTS.......................... 11 49 20 34 / 20 0 20 20 QUEMADO......................... 17 46 21 31 / 0 0 0 30 GLENWOOD........................ 15 53 26 44 / 0 0 0 10 CHAMA........................... 10 32 13 25 / 60 10 50 50 LOS ALAMOS...................... 19 40 20 30 / 40 0 10 40 PECOS........................... 18 37 20 30 / 50 0 0 40 CERRO/QUESTA.................... 3 37 11 27 / 60 0 20 60 RED RIVER....................... 5 32 10 20 / 80 5 30 70 ANGEL FIRE...................... -3 31 12 24 / 80 5 10 60 TAOS............................ 9 39 15 30 / 60 0 10 50 MORA............................ 15 42 17 29 / 50 0 0 50 ESPANOLA........................ 14 45 21 36 / 30 0 0 30 SANTA FE........................ 21 41 21 31 / 60 0 0 40 SANTA FE AIRPORT................ 18 44 23 34 / 40 0 0 30 ALBUQUERQUE FOOTHILLS........... 26 48 27 36 / 50 0 0 30 ALBUQUERQUE HEIGHTS............. 26 51 28 40 / 30 0 0 20 ALBUQUERQUE VALLEY.............. 22 52 25 41 / 30 0 0 10 ALBUQUERQUE WEST MESA........... 24 54 27 41 / 40 0 0 20 LOS LUNAS....................... 20 52 24 43 / 20 0 0 10 RIO RANCHO...................... 25 51 27 39 / 40 0 0 20 SOCORRO......................... 22 58 26 48 / 5 0 0 10 SANDIA PARK/CEDAR CREST......... 21 47 25 34 / 60 0 5 40 TIJERAS......................... 22 48 27 36 / 50 0 0 30 MORIARTY/ESTANCIA............... 21 45 23 34 / 40 0 0 20 CLINES CORNERS.................. 17 42 21 32 / 40 0 0 30 GRAN QUIVIRA.................... 21 45 24 37 / 10 0 0 20 CARRIZOZO....................... 21 50 28 44 / 0 0 0 20 RUIDOSO......................... 22 45 26 37 / 5 0 0 30 CAPULIN......................... 14 41 21 30 / 70 0 5 60 RATON........................... 14 47 23 34 / 50 0 5 50 SPRINGER........................ 17 49 23 35 / 40 0 0 40 LAS VEGAS....................... 14 47 23 32 / 40 0 0 40 CLAYTON......................... 20 48 27 36 / 50 0 0 40 ROY............................. 21 48 27 35 / 30 0 0 40 CONCHAS......................... 26 57 30 44 / 20 0 0 20 SANTA ROSA...................... 25 55 28 45 / 10 0 0 20 TUCUMCARI....................... 24 59 32 46 / 10 0 0 20 CLOVIS.......................... 24 56 30 48 / 5 0 0 10 PORTALES........................ 27 58 30 51 / 5 0 0 10 FORT SUMNER..................... 26 58 28 49 / 5 0 0 10 ROSWELL......................... 28 64 32 59 / 0 0 0 10 PICACHO......................... 24 58 33 52 / 0 0 0 10 ELK............................. 23 55 34 48 / 0 0 0 20 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
223 AM EST THU FEB 21 2013 .SYNOPSIS... A NORTHWEST FLOW OF COLD AIR ACROSS THE FINGER LAKES WILL KEEP LAKE EFFECT SNOW SHOWERS OVER CENTRAL NEW YORK INTO THURSDAY... ALTHOUGH THE SNOW SHOWERS WILL WEAKEN AS HIGH PRESSURE BUILDS IN AND SLOWLY CLEARS OUR SKIES. IT WILL REMAIN MOSTLY DRY ON FRIDAY BEFORE A COMPLEX STORM SYSTEM OVER THE GREAT LAKES AND MID ATLANTIC COAST PUSHES MIXED PRECIPITATION INTO THE AREA. && .NEAR TERM /THROUGH TODAY/... 950 PM UPDATE... LAKE BAND IS FINALLY SHOWING SIGNS OF A SOUTHWARD PUSH. WILL CONTINUE GRID FORECAST UPDATED A FEW YEARS AGO, WITH THE NEXT TARGET BECOMING NORTHERN ONONDAGA COUNTY. BAND IS STILL FORECAST TO WEAKEN QUICKLY DUE TO COLLAPSING INVERSION HEIGHTS. 750 PM UPDATE... STILL NO MOVEMENT SOUTHWARD TO LAKE BAND, WHICH IS SHOWING A LITTLE MORE ORGANIZATION DEVELOPING. LATEST RAP DROPS THE BAND INTO ONONDAGA COUNTY AROUND 3Z AND WEAKENS IT THEREAFTER. AT THIS POINT I HAVE A HEALTHY DOSE OF SKEPTICISM REGARDING THE NEWEST MESOSCALE MODEL RUNS, AS OTHERS HAVE HANDLED THE SITUATION POORLY. SFC WIND AND PRESSURE OBSERVATIONS ARE NOT SUGGESTING A BIG MOVE COMING. COULD ARGUE FOR EXTENDING THE ADVISORY FOR N. ONEIDA, BUT DO NOT ANTICIPATE MORE THAN AN ADDITIONAL INCH OR TWO TONIGHT. 610 PM UPDATE... LAKE EFFECT BAND IS DEFYING THE SHORT TERM MODELS, AND IS RESISTING THE FORECAST TO DRIFT SOUTHWARD INTO ONONDAGA COUNTY. THE BAND HAS ALSO WEAKENED CONSIDERABLY IN THE LAST HOUR, THOUGH WITH NIGHTTIME UPON US AND DAYTIME THERMALS LONG GONE, IT WOULD NOT BE SURPRISING TO SEE REORGANIZATION. THE GRIDS HAVE BEEN ADJUSTED TO DELAY THE LES ONSET INTO ONONDAGA- MADISON BY 1-2 HOURS. WILL CONTINUE TO MONITOR BAND STRENGTH ONCE IT MAKES ITS MOVE FOR POTENTIAL ADVISORY. SHOULD CURRENT RADAR TRENDS HOLD, THERE WILL BE NO NEED FOR A FLAG. 3 PM UPDATE... MESO SCALE MODELS AND FCST SNDGS SHOW THE BAND SLOWLY DRFTG SOUTH OVRNGT AND WEAKENING. CRNT KTYX 88D IMAGES SHOW A SOMEWHAT MORE DISORGANIZED BAND NOW IN THE ADVISORY AREA AND INDEED VERY SLOWLY MVG SOUTH. SOMEWHAT CNRND THAT ANOTHER SPOKE ROTATING ARND THE UPR LOW COULD DELAY THE SWRD MVMT AND QUICKLY GIVE PART OF THE FCST AREA NEAR ADVISORY SNOW THIS EVE. AIR STILL PLENTY COLD WITH -14C AIR CORE OVER THE LAKE. HWVR...SINKING MOTION SHOWN IN THE SNDGS CONTS TO LWR THE INV PTNLY WEAKENING THE BAND REGARDLESS OF THE FLOW. ATTM WILL CONT WITH THE ADVISORY FOR NRN ONEIDA AND PUT ACCUMS JUST BLO CRITERIA IN NRN ONONDAGA AND SRN ONEIDA. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... LE WILL LINGER INTO THU WITH CONTD COLD AIR AND NW FLOW. HIPRES SFC AND ALOFT FNLY BLDS IN FOR FRI AS THE CLSD LOW DRIFTS EAST IN RESPONSE TO THE DVLPG COMPLEX OVER THE CNTR OF THE COUNTRY. FRI LOOKS SUNNY WITH SLGTLY ABV NRML TEMPS. COMPLEX SCENARIO AND TRICKY FCST UNFOLDING FOR THE END OF THE SHRT TERM. YET ANOTHER CLSD LOW OVER THE GREAT LAKES TRIES TO PHASE WITH A SRN STREAM SHRT WV TRAVELING UP THE EAST CST. MODELS TYPICALLY HAVE TROUBLE WITH DVLPG LOWS AND THIS IS COMPLICATED BY THE DFCLTY IN PLACING THE MEANDERING CLSD UPR LOW OVER THE WRN LAKES. CONSENSUS NOW IS TO DVLP THE SRN STREAM IMPULSE ENOUGH TO PUSH MORE SUBSTANTIAL PCPN BACK INTO THE SERN ZONES...NAMELY THE PA AND THE WRN CATS. OTR COMPLICATING FACTOR IS PCPN TYPE WITH A COMPLETE LACK OF COLD AIR...EVEN OVER NRN NEW ENG. SO...IT LOOKS VERY MUCH LIKE AN EARLY SPRING LIKE SCENARIO WITH MIXED PCPN...OR LRG VLY/HILL DFRNCS. CNRT WWE FCST GIVE THE SERN ZONES A 4 TO 6 INCH ACCUM...2 TO 4 ELSEWHERE. WILL CONT A MENTION IN THE HWO FOR NOW AND XPCT CONTG CHGS TO THE FCST AS THE WEEKEND APRCHS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... 1 PM UPDATE... BLOCKY PATTERN WITH TWO CLOSED LOWS MOVING THROUGH IN THE LONG TERM. BOTH APPEAR TO BE MINOR FOR THE CWA. THE FIRST WILL BE FRIDAY TO SUNDAY. THE UPPER LEVEL LOW WILL BE IN THE GREAT LAKES SAT NGT WITH A NOREASTER FORMING. MOST MODELS HAVE A NEAR MISS. THE TROF GOES NEGATIVE TILT WHICH SLOWS THE SNOW FROM EXITING UNTIL SUNDAY. A WEAK LAKE RESPONSE ON THE BACK SIDE OF THE STORM SUNDAY NIGHT TO MONDAY. LATE MONDAY A LARGE AREA OF HIGH PRESSURE MOVES IN AT THE SFC AND ALOFT. TUESDAY TO WEDNESDAY DO IT ALL OVER AGAIN WITH ANOTHER STACKED LOW. THE EURO HANDLES THIS STORM SLOWER WITH THE LOW IN ILLINOIS TUES MORN MOVG TO SSM WED. WARM AIR COMES NORTH WITH THE OCCLUDED FRONT SO PRECIP WILL BE MIXED. THE GFS BRINGS THE STACKED LOW ENE OVER NY/PA SO A BETTER CHC OF SNOW. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... 06Z UPDATE... A COLD NORTHWEST FLOW WILL PERSIST THROUGH THIS TAF PERIOD BRINGING A CONTINUATION OF SNOW SHOWERS AND FLURRIES. THE BEST CHANCE FOR MORE ORGANIZED LAKE SNOWS WILL BE THROUGH 12Z ESPECIALLY AT KSYR AND KRME...WITH A GRADUAL TRANSITION TO LIGHTER SNOW FLURRIES AND SHOWERS FOR THE REMAINDER OF THURSDAY. AT KRME...GENERALLY IFR WILL CONTINUE THROUGH 09Z IN STEADYER SNOW SQUALLS. AFTER 09Z THE HEAVIER BAND WILL THEN DROP SOUTH OF THE TERMINAL WITH MVFR SNOW SHOWERS EXPECTED THROUGH DAYBREAK WITH A GRADUAL RETURN TO VFR WITH CIGS AROUND 3,500 FT AFTER THAT TIME. AT KSYR...IFR WITH OCCASIONAL BELOW ALT MIN CONDITIONS THROUGH 09Z. AFTER 09Z SOME IMPROVEMENT POSSIBLE BUT CONFIDENCE NOT HIGH ENOUGH AND ELECTED TO KEEP THE POSSIBILITY OF IFR VSBYS IN THROUGH 12Z. AFTER THAT TIME WE SHOULD IMPROVE TO MVFR IN SNOW SHOWERS AND FLURRIES THROUGH AFTERNOON. AT KITH/KBGM...GENERALLY MVFR CONDITIONS DUE TO CIGS WITH OCCASIONAL MVFR VSBY RESTRICTIONS IN SNOW SHOWERS THROUGH DAYBREAK. FLURRIES AND BRIEF HEAVIER SQUALLS LIKELY TO PERSIST THROUGH THURSDAY AFTN AT KITH. AT KELM/KAVP...GENERALLY VFR WITH CIGS AROUND 4K FT AND SNOW FLURRIES. WEST WINDS 10-15 KNOTS WITH GUSTS AROUND 25 KNOTS DURING THE DAYLIGHT HOURS ON THURSDAY. .OUTLOOK... THU NGT/FRI MORN...VFR. FRI AFTN TO SAT NGT...MVFR/IFR IN MIXED PCPN. SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS. MON...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DGM NEAR TERM...DGM/DJP SHORT TERM...DGM LONG TERM...TAC AVIATION...HEDEN/RRM
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1015 PM EST FRI FEB 22 2013 .SYNOPSIS... LOW PRESSURE WILL APPROACH FROM THE SOUTHWEST TONIGHT AND MOVE ACROSS EASTERN NORTH CAROLINA SATURDAY. HIGH PRESSURE WILL PASS TO THE NORTH SUNDAY NIGHT AND MONDAY. LOW PRESSURE AND ITS TRAILING COLD FRONT WILL MOVE THROUGH TUESDAY. LOW PRESSURE WILL LINGER OVER THE MID ATLANTIC STATES WEDNESDAY AND THURSDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 1014 PM FRI...SHOWERS STILL REMAIN ISOLATED OVER EASTERN NC TONIGHT WITH MAIN BULK OF RAIN IN GA. NICE CONVERGENCE ALONG THE COAST AS TROUGH GAINS BETTER DEFINITION. RUC CONTINUES TO HAVE BEST HANDLE ON CURRENT PATTERN. IT MOVES THE MAIN PRECIP INTO NC AROUND SUNRISE. WILL ADJUST TIMING IN GRIDS. NEW FORECAST SOUNDINGS DRYING THINGS OUT A LITTLE SOONER THAN PREVIOUS...BUT THAT IS IN THE NEXT PERIOD. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... AS OF 315 PM FRI...WIDESPREAD RAIN CONTINUES FOR THE FIRST HALF OF SATURDAY AS LOW PRESSURE TRACKS DIRECTLY ACROSS EASTERN NORTH CAROLINA. DUE TO THE LOW TRACK...HIGHS ALONG THE COASTAL PLAIN WILL BE IN THE UPPER 40S TO LOWER 50S...BUT CLOSER TO THE COAST IN THE WARM SECTOR HIGHS WILL CLIMB TO THE UPPER 50S TO NEAR 60. RAIN WILL TAPER OFF IN COVERAGE BEGINNING AROUND MIDDAY AND CONTINUING INTO THE AFTERNOON AS THE LOW MOVES OFF TO THE NORTHEAST. LOOKS LIKE ANOTHER INCH OR SO POSSIBLE FROM DAYBREAK SATURDAY THROUGH MIDDAY...WITH LIGHTER AMOUNTS IN THE AFTERNOON. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... AS OF 315 PM FRI...PRECIPITATION WILL BE GRADUALLY TAPERING OFF SAT NIGHT AS MID LEVEL SHORT WAVE CROSSES THE AREA LATE AT NIGHT. WITH HIGH PRESSURE BUILDING IN FROM THE OHIO VALLEY UNDER WNW FLOW ALOFT...THE LATTER HALF OF THE WEEKEND WILL BE DRY AND SEASONAL WITH HIGHS SUNDAY IN THE UPPER 50S AND LOWER 60S WITH LOWS SUNDAY NIGHT IN THE MID TO UPPER 30S INLAND TO LOW 40S COAST. CLOUDING UP ON MONDAY AS THE NEXT SOUTHERN STREAM SYSTEM LIFTS NE OF THE GULF COAST. MAY SEE SOME LIGHT RAIN REACH SOUTHERN AREAS DURING THE AFTN BUT THE BULK OF THE PRECIPIATATION WILL BE WITH A NORTHWARD MOVING WARM FRONT LATER MON NIGHT INTO EARLY TUE. MAY ALSO SEE SCATTERED SHOWERS ALONG AND AHEAD OF ASSOCD COLD FRONT TUESDAY AFTN/EVE. RAINFALL AMOUNTS MAY AGAIN EXCEED AN INCH WITH THIS SYSTEM. HIGHS MONDAY WILL BE HELD IN THE 50S BY INCREASING AFTN CLOUD COVER TEMPS BUT WILL REBOUND INTO THE LOW 60S OR HIGHER IN BRIEF WARM SECTORING TUE AFTN. WED WILL BE DRY AND A BIT COOLER AS WEAK HIGH PRESSURE BUILS INTO THE AREA. UPPER PATTERN WILL BECOME HIGHLY AMPLIFIED DURING THE END OF THE WEEK AS A DEEP TROF DEVELOPS OVER THE EASTERN STATES. SHUD SEE A SERIES OF MAINLY DRY COLD FRONTAL PASSAGES GIVEN THE APPARENT LACK OF DEEP MOISTURE SOURCES IN THE OVERALL WESTERLY FLOW. TEMPS WILL SHOW A GRADUAL COOLDOWN AS POST FRONTAL CAA SETS IN. HIGHS IN THE MID 50S THU WITH UPPER 40S TO LOW 50S FRI. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... SHORT TERM /TONIGHT & SAT/ AS OF 625 PM FRI...FEW LIGHT SHOWERS ACROSS AREA TAFS THIS EVENING. MAIN AREA OF PRECIP STILL IN GA/AL AREA. RUC/RAP MODEL HAS BEST HANDLE ON CURRENT CONDITIONS AT THIS TIME...EVEN THOUGH THEY ARE A LITTLE OVERDONE. AREA SOUNDINGS SHOWING NON-SATURATED LOWER LEVELS...BUT FORECAST SOUNDINGS SHOWING LOWER LEVELS WILL SATURATE IN THE NEXT FEW HOURS. LOOKS LIKE THE MAIN BULK OF THE PRECIP WILL GET TO EASTERN NC AROUND 7 TO 8Z. IFR/LIFR CONDITIONS EXPECTED LATER TONIGHT AND THROUGH MUCH OF THE DAY SATURDAY. SOME MODELS SHOWING FORCING MOVING A BIT EAST COMPARED TO PREVIOUS GUIDANCE. WILL KEEP AN EYE ON THINGS...BUT EITHER WAY WILL HAVE LOWERED VIS/CIG THROUGH THE DAY. LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 315 PM FRI...SUB-VFR CONDITIONS LINGER INTO SAT NIGHT THEN IMPROVING FLYING CONDITIONS AS DEEPER DRYING SETS IN BEHIND A A COLD FRONT MOVING OFFSHORE EARLY SUNDAY. EXPECT VFR SUNDAY AND MONDAY BEFORE LIKELY SUB-VFR THRESHOLDS AHEAD OF A LOW PRESSURE SYSTEM MOVING NE FROM THE GULF MONDAY NIGHT INTO TUESDAY. CONDITIONS IMPROVE AGAIN WITH VFR EXPECTED TUESDAY NIGHT INTO WEDNESDAY AS COLD FRONT PASSES EAST OF THE AREA. && .MARINE... SHORT TERM /TONIGHT & SAT/... AS OF 1015 PM FRI...NORTHEASTLY WIND AROUND 10 KNOTS THIS EVENING OVER THE COASTAL WATERS. CONVERGENCE ALONG THE COAST WITH RIDGING IN THE CENTRAL PART OF THE STATE. WIND WILL BECOME MORE SOUTHEASTERLY AS COASTAL CONVERGENCE BECOMES MORE WELL DEFINED. WAVE WILL FORM ALONG THE COASTAL TROUGH OFF SC/GA TONIGHT AND RIDE UP ALONG THE COAST AS IT DEEPENS. WIND AND SEAS WILL PICK UP AS SURFACE LOW PRESSURE APPROACHES THE AREA AND GRADIENT TIGHTENS. MAIN BULK OF RAIN WILL GET TO THE COASTAL WATERS BETWEEN MIDNIGHT AND SUNRISE AND WILL CONTINUE THROUGHOUT THE DAY ON SATURDAY WITH REDUCED VISIBILITIES AND HEAVY RAINFALL LIKELY. LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 315 PM FRI...COLD FRONT PASSES THRU THE MARINE AREA SAT EVENING WITH SCA CONDITIONS CONTINUING THRU EARLY SUNDAY. WINDS/SEAS GRADUALLY DECREASE SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NW. WINDS THEN VEER AND INCREASE AGAIN MONDAY AHEAD OF THE NEXT LOW PRESSURE SYSTEM LIFTING NE FROM THE GULF COAST. WINDS/SEAS LIKELY EXCEED SCA CRITERIA LATE MONDAY NIGHT INTO TUESDAY AS WINDS SHIFT SW BEHIND WARM FRONT PUSHING NORTH OF THE AREA. WINDS/SEAS DECREASE AGAIN WED AS WEAK HIGH PRESSURE BUILDS OVER THE AREA. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 AM SATURDAY TO 7 AM EST SUNDAY FOR AMZ152-154. SMALL CRAFT ADVISORY FROM 1 AM SATURDAY TO 1 AM EST SUNDAY FOR AMZ156-158. SMALL CRAFT ADVISORY FROM 7 AM TO 9 PM EST SATURDAY FOR AMZ150. && $$ SYNOPSIS...HSA NEAR TERM...CGG SHORT TERM...HSA LONG TERM...BTC AVIATION...CGG/BTC MARINE...CGG/BTC
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
950 AM CST THU FEB 21 2013 .DISCUSSION... FORECAST CHALLENGE FOR UPDATE CONCERNS CLOUD TRENDS AND TEMPERATURES. SEVERAL CLOUD AREAS TO POTENTIALLY AFFECT FA TODAY. VFR CIGS CONTINUE TO LIFT NORTH THROUGH FAR WESTERN FA. ALSO SOME WEAK RETURNS FROM KMVX-88D OVER DVL BASIN HOWEVER METARS SO FAR REPORTING NO PCPN AND RETURNS LIKELY PICKING UP ON CIGS. WITH NEAREST MEASURABLE SNOW FROM BIS-MOT WILL JUST MENTION FLURRIES REMAINDER OF AM. CI SHIELD FROM CENTRAL PLAINS STORM LIFTING N AROUND 35KTS AND CURRENT TRENDS WOULD HAVE MOST OF FA AFFECTED BY CI BY EARLY AFTERNOON. STILL NOT MUCH CONFIDENCE ON DEGREE OF WESTWARD ADVANCE OF STRATUS COMING OFF OF LAKE SUPERIOR AND WILL CONTINUE TO MONITOR FOR AVIATION PURPOSES. WITH FILTERED SOLAR AFFECTING MOST AREAS FEEL CURRENT TEMPERATURES IN LINE SO WILL BE MAKING MINIMAL CHANGES. WILL MAKE THE POP AND CLOUD TREND ADJUSTMENTS WITH THE REMAINDER OF THE FORECAST OK. && .AVIATION... EXPECT VFR CONDITIONS WITH SOME LOWER VFR CIGS NEAR KDVL FOR TODAY. WILL NEED TO MONITOR THE POTENTIAL FOR LOWER CIGS ADVECTING INTO THE REGION FROM THE EAST THIS AFTERNOON. 12Z RAP INDICATES LOWER CIGS ACROSS NORTHEAST MINNESOTA WILL EXPAND WESTWARD...AND OBSERVATIONS HAVE SHOWN SOME WESTWARD MOVEMENT OF THE LOWER CIGS. WILL AT LEAST HINT AT A LOWER CLOUD DECK FOR KBJI THIS AFTERNOON IN THE TAF. .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER/JAM
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
311 AM CST THU FEB 21 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) CHALLENGE WILL BE TEMPERATURES AND LIGHT SNOW CHANCES. 00Z MODELS IN AGREEMENT AND WILL USE A BLEND FOR THE FORECAST. NO BIG CHANGES REQUIRED TO THE FORECAST. COULD BE SOME FLURRIES OR VERY LIGHT SNOW ACROSS THE DEVILS LAKE BASIN THIS MORNING...BUT MODELS ALL INDICATE RIDGING AND LOW LEVEL EASTERLY DRY FLOW WILL KEEP ACCUMULATING SNOWFALL TO THE WEST. HAVE REMOVED POPS/WX FOR TODAY INTO THE EVENING HOURS. AFTER MIDNIGHT...UPPER LOW WILL TRACK INTO IOWA AND CONTINUE SLOWLY INTO NORTHERN WISCONSIN BY FRIDAY EVENING. THE SOUTHEAST FA WILL BE NEAR THE NORTHERN END OF SNOW SHIELD...AND MODELS ALL AGREE AROUND AN INCH OF SNOW POSSIBLE ON BY FRIDAY AFTERNOON. KEPT THE IDEA OF HIGH POP/LOW QPF. RIDGING THEN DOMINATES ON SATURDAY. TEMPERATURES WILL BE CHALLENGING AND HIGHLY DEPENDENT ON CLOUD COVER...ESPECIALLY AT NIGHT. FOR TODAY...WITH SOLAR EXPECTED ACROSS THE EASTERN FA...THINKING THE FORESTED AREAS WILL BE ABLE TO WARM INTO THE MID/UPPER 20S. WITH A WARMER START COMPARED TO YESTERDAY...THE REMAINDER OF THE FA SHOULD BE ABLE TO WARM INTO THE TEENS. MID-UPPER CLOUDS EXPECTED TO OVERTAKE THE REGION TONIGHT...WHICH WILL LIMIT TEMPERATURE FALL. THE MAIN QUESTION WILL BE AREAS THAT ARE CLEAR THIS EVENING...AND HOW FAR THEY WILL FALL BEFORE CLOUDS ARRIVE. ON FRIDAY...EXPECT MOSTLY CLOUDY SKIES WHICH WILL LIMIT MAX TEMPS ACROSS THE REGION TO AROUND 20F. WEAK FLOW AND SIMILAR AIRMASS TEMPERATURES REMAIN INTO SATURDAY. IF THERE IS SOLAR ON SATURDAY EXPECT THE FORESTED AREAS TO BE WARMER...AND IF/WHERE SKIES ARE CLEAR AT NIGHT EXPECT VALUES JUST BELOW ZERO. DID LOWER MIN TEMPS A BIT...BUT NOT TOO CRAZY. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) MEDIUM-RANGE MODELS AGREE THAT THE NORTHERN PLAINS WILL BE IN A SPLIT FLOW PATTERN WITH THE MAJORITY OF SYNOPTIC ENERGY ACROSS THE SOUTHERN CONUS. ANOTHER FOUR CORNERS LOW AND ITS SNOW MAY CLIP THE SOUTHEASTERN FORECAST AREA EARLY NEXT WEEK...BUT OVERALL MODEL TRENDS CONTINUE TO KEEP THE MAJORITY OF PRECIPITATION SOUTH AND EAST INTO MN/WI/IA. SEVERAL WEAK WAVES COULD IMPACT THE REGION THROUGH THE PERIOD...BUT MODEL TIMING AND PLACEMENT AGREEMENT IS POOR. AS A RESULT...WILL KEEP LOW-END (20-30 PERCENT) ALL BLEND POPS. WITH NO MAJOR CHANGES IN AIR MASS...EXPECT LITTLE DAY TO DAY TEMPERATURE VARIATION. AFTERNOON HIGHS WILL BE IN THE 20S AND NIGHTTIME LOWS WILL BE IN THE TEENS. && .AVIATION... EXPECT VFR CONDITIONS WITH SOME LOWER VFR CIGS NEAR KDVL FOR TODAY. WILL NEED TO MONITOR THE POTENTIAL FOR LOWER CIGS ADVECTING INTO THE REGION FROM THE EAST THIS EVENING. 06Z RAP INDICATES LOWER CIGS ACROSS NORTHERN WISCONSIN WILL EXPAND. CONFIDENCE IS LOW THAT THIS WILL ACTUALLY OCCUR...BUT SOMETHING TO MONITOR. .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG/ROGERS
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
807 PM CST FRI FEB 22 2013 .UPDATE... LATEST REGIONAL RADAR IMAGERY SHOWS SCATTERED RAIN ACROSS NORTHERN MISSISSIPPI AND ALABAMA INTO EAST TENNESSEE. ACTIVITY HAS BEEN REMAINING TO THE SOUTHEAST OF THE CWA SO FAR...AND APPEARS THIS TREND WILL CONTINUE THROUGH MUCH OF THE NIGHT WITH ONLY THE FAR EASTERN AND SOUTHEASTERN ZONES LIKELY TO BE AFFECTED BY ANY PRECIP. WITH SHORT TERM GUIDANCE INCLUDING THE HRRR AND 00Z NAM AGREEING WITH THIS SCENARIO...WILL TRIM POPS BACK FURTHER TOWARDS THE SOUTHEAST. WILL ALSO KEEP IN MENTION OF PATCHY FOG OVER THE SOUTHEAST HALF OF THE CWA AS DEWPOINT DEPRESSIONS ARE ALREADY LOW...AND WILL BE SEVERAL HOURS BEFORE APPROACHING COLD FRONT OVER NORTHWEST ZONES REACHES THIS AREA. REST OF FORECAST APPEARS TO BE ON TRACK. && .PREV DISCUSSION... /ISSUED 641 PM CST FRI FEB 22 2013/ UPDATE...FOR 00Z TAFS... AVIATION... MAINLY VFR CONDITIONS THIS EVENING FOR CKV AND BNA. AFTER MIDNIGHT CEILINGS ARE EXPECTED TO LOWER TO MVFR CONDITIONS...WITH IFR CONDITIONS POSSIBLE IN NASHVILLE AS CIGS DROP BELOW 1000 FEET IN THE EARLY MORNING HOURS. CONDITIONS AT CSV REMAIN WITHIN IFR CONDITIONS WITH CONDITIONS DETERIORATING AS THE NIGHT PROGRESSES. CEILINGS ARE FORECAST TO CONTINUE LOWERING THIS EVENING AS A BAND OF MOISTURE MOVES JUST SOUTH AND EAST OF THE MID STATE. VIS AT CSV MAY BE REDUCED TO 1 MILE OR LESS SATURDAY MORNING DUE TO FOG. CONDITIONS SHOULD IMPROVE CLOSER TO NOON ON SATURDAY AS A FRONT PASSES THROUGH THE AREA. PREV DISCUSSION... /ISSUED 320 PM CST FRI FEB 22 2013/ DISCUSSION... TEMPS DROP OFF CONSIDERABLY TO THE WEST OF NASHVILLE BEHIND THE COLD FRONT. THIS BOUNDARY IS RUNNING PARALLEL TO THE UPPER FLOW BUT WILL SLOWLY MOVE THROUGH AND WILL REACH EAST TN TONIGHT. THE BOUNDARY WILL THEN SLOW DOWN AND STALL. SFC ENERGY WILL THEN LIFT NE ALONG THE BOUNDARY AND SPREAD MOISTURE NORTHWARD. LOOKS AS THOUGH THE MOISTURE WILL FOR THE MOST PART STAY SOUTH OF MIDDLE TN. ALTHOUGH...SOME SHOWER ACTIVITY COULD REACH THE PLATEAU AND SRN AREAS OVERNIGHT. WILL INCLUDE LOW POPS FOR EASTERN AND SOUTHERN PORTIONS. OTHERWISE...DESPITE THE FROPA AND SOME LOWERING DEW POINTS...DEW POINT DEPRESSIONS WILL BE RATHER LOW BY 12Z...PARTICULARLY ACROSS THE EASTERN HALF OF THE CWA. WILL ALSO INCLUDE SOME PATCHY LATE NIGHT FOG. ON SATURDAY...SFC HIGH WILL BUILD IN WITH SOME DRIER AIR WINNING OUT. THIS TREND WILL CONTINUE INTO SUNDAY...AND WITH AMPLIFIED HEIGHTS...SHOULD SEE TEMPS BACK UP INTO THE 50S FOR BOTH DAYS. IN THE EXT FCST...MODELS ARE CONTINUING TO TREND TOWARD A COLDER AND SOMEWHAT UNSETTLED PATTERN. UPPER LEVEL TROUGHING IS EXPECTED WITH SEVERAL DISTURBANCES MOVING THROUGH THE AREA. THE FIRST SYSTEM WILL BE ON MONDAY WITH A POTENT NEGATIVELY TILTED UPPER LOW AXIS. THIS FEATURE WILL PASS NORTH OF TN AND WILL DRAG AN ASSOCIATED FROPA THROUGH ON TUESDAY. RAIN PROBABILITIES LOOK HIGH FOR MONDAY INTO TUESDAY. SYNOPTIC FEATURES SUPPORT THE POTENTIAL FOR SOME WRAP AROUND SNOWFALL. HOWEVER...MODEL SFC TEMPS LOOK TOO WARM AND EVEN A 5 DEGREE UNDERCUT WILL NOT SUPPORT SUFFICIENTLY LOW ENOUGH FREEZING LEVEL SUPPORT. THUS...WILL LEAN TOWARD MOSTLY RAIN FOR TUESDAY. WED NT INTO THU...NEXT IMPULSE TO MOVE THROUGH. MODELS CONVERGE TO SUPPORT TEMPS THAT WILL BE COLD ENOUGH TO SUPPORT AM RAINFALL/SNOWFALL...RAIN IN AFTERNOON. SYSTEM DOES NOT CARRY AN ABUNDANCE OF ORGANIZATION SO WILL KEEP POPS LOW. GFS THEN LEANS TOWARD YET ANOTHER DISTURBANCE FOR FRIDAY. WILL OPT TO KEEP A FLURRIES OR LIGHT SNOW SHOWERS GOING THU NT AD FRIDAY. FOR THE EXT TEMPS...IT WILL BE DO OR DIE TIME VERSUS THE GUIDANCE. MEX IS CARRYING HIGHS OF 45 TO 50 FOR BNA. THE MODELS ARE ALL CONVERGING ON LOW HEIGHTS...CLOUDS AND SOME PRECIP...AD 850 MB TEMPS OF UP TO -5 TO -10. WILL ROLL THE DICE AND UNDERCUT THE MEX NUMBERS DECISIVELY. PERHAPS JUST A SLIGHT UNDERCUT ON OVERNIGHT LOWS. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 55
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1133 PM CST WED FEB 20 2013 .AVIATION... WILL MAINTAIN CONTINUITY OF PREVIOUS FORECASTS CONCERNING TIMING OF SQUALL LINE AND COLD FRONT. HOWEVER...WE DID MODIFY THE TIMING OF LOWERING CLOUD BASES AND ARRIVAL OF IFR CIGS ACROSS THE METROPLEX AND KACT. SHRA ACTIVITY WILL INCREASE FOR KACT AFTER 07Z AS THE SFC-850 FRONT LIFTS NORTHWARD AND FORCING FOR LIFT INCREASES. AS FOR THE METROPLEX...WE/RE LOOKING FOR THIS PROCESS TO GEAR UP 08-10Z. THE TIMING OF THE SQUALL LINE STILL LOOKS GOOD...13-16Z FOR THE METROPLEX AND 14-16Z FOR KACT. LOW-LEVEL WIND SHEAR WILL REMAIN A PROBLEM TONIGHT AS LOCAL 88D RADAR VAD PROFILES SHOW 50+ KNOTS AROUND 2-3 KFT AND GENERALLY 25-30 KNOTS AT 1 KFT AGL. HAVE INCLUDE THIS CAUTION IN ALL TAFS. 75 && .UPDATE... A MINOR UPDATE TO LOWER RAIN CHANCES THROUGH LATE EVENING INTO THE FIRST FEW HOURS OF THURSDAY MORNING...AS NORTH TEXAS IS IN A LULL BETWEEN DISTURBANCES. THE FIRST DISTURBANCE THAT GAVE THE RAIN AND A LITTLE BIT OF SLEET TO PARTS OF NORTH TEXAS EARLIER TODAY IS HEADING AWAY FROM THE AREA AND CAUSING WINTER WEATHER PROBLEMS ACROSS PARTS OF OKLAHOMA INTO ARKANSAS/MISSOURI. THE MAIN SYSTEM THAT WILL AFFECT NORTH TEXAS BY DAYBREAK THURSDAY MORNING IS JUST STARTING TO ROTATE OUT OF ARIZONA AND INTO WESTERN NEW MEXICO AT 9 PM. LINEAR FORCING WAS HELPING TO DEVELOP A LINE OF STORMS ACROSS FAR SOUTHEAST NEW MEXICO AND TO THE TEXAS STATE LINE. NOT ALL MODELS ARE IN SUCH AS THE 00Z GFS...HOWEVER THE 00Z NAM...TEXAS TECH WRF AND HRRR MODELS ARE SHOWING IT WILL BE AFTER 3 AM BEFORE THINGS BEGIN TO GET ACTIVE ACROSS THE WESTERN HALF OF THE AREA. ONE THING TO NOTE OF THE WRF AND 00Z NAM MODELS HOWEVER WAS THEY WERE TOO FAR EAST FROM LUBBOCK TO MIDLAND WITH THE DEVELOPING SQUALL LINE AT MID EVENING. THE SURFACE WARM FRONT WHICH IS NOW OVER SOUTH-CENTRAL TEXAS WILL ONLY CREEP NORTH WITH THE BEST NORTHWARD SURGE OCCURRING WEST/SOUTHWEST OF OUR AREA CLOSER TO THE BETTER HEIGHT FALLS AND SURFACE LOW CURRENTLY OVER ALPINE AND FAR WEST TEXAS. STRONG 850MB WAA WILL SLIDE EAST ACROSS WESTERN NORTH TEXAS BETWEEN 3-6 AM...AND THIS WILL BE THE TIME STORMS AND A FEW SUPERCELLS WILL DEVELOP. BEST CHANCE FOR SURFACE-BASED SEVERE STORMS WITH DAMAGING WINDS AND TORNADOES WILL BE IN A LIMITED TIME WINDOW FROM 5AM-9AM AND GENERALLY SOUTH OF A HAMILTON-WACO-ATHENS OR PALESTINE LINE. WITH 0-6KM SOUTHWESTERLY SHEAR ON THE ORDER OF 70-90 KTS AND SOMEWHAT VEERED 0-1KM ON THE ORDER OF 40-50 KTS...SUPERCELLS ARE HIGHLY LIKELY. ELEVATED SUPERCELLS WILL OCCUR NORTH OF THE WARM FRONT WITH VERY LARGE HAIL...FREQUENT LIGHTNING...AND HEAVY DOWNPOURS THE MAIN THREATS. WE WILL CONTINUE TO MONITOR THIS SYSTEM DURING THE OVERNIGHT AND URGE EVERYONE TO KEEP ON EYE THINGS AS THEY WAKE UP AND BEFORE HEADING OUT FOR THE MORNING COMMUTE THURSDAY MORNING. SPOTTER AND HAMS COULD EASILY BE ACTIVATED ACROSS THE WESTERN HALF OF THE CWA BEFORE SUNRISE. 05/ && .PREV DISCUSSION... /ISSUED 330 PM CST WED FEB 20 2013/ CLOUDY AND COOL CONDITIONS PERSIST ACROSS THE REGION THIS AFTERNOON WITH JUST A FEW SCATTERED AREAS OF LIGHT RAIN/SHOWERS ACROSS THE REGION. THE UPPER LEVEL SYSTEM THAT WE HAVE BEEN MONITORING TO BRING US STORMS AND A THREAT FOR SEVERE WEATHER TONIGHT/THURSDAY IS NOW MOVING INTO SOUTHERN ARIZONA. THE ASSOCIATED PACIFIC FRONT IS ALSO MOVING INTO ARIZONA...AND THIS ENTIRE SYSTEM HAS QUITE A WAYS TO TRAVEL BEFORE ARRIVING IN NORTH AND CENTRAL TEXAS. FOR THE REST OF TODAY AND EARLY TONIGHT...RAIN ACTIVITY WILL BE ISOLATED TO SCATTERED IN NATURE BUT OVERALL IT WILL BE A QUIET EVENING. THEREFORE LOWERED POPS FOR THE EVENING HOURS AND ALSO REMOVED THE MENTION OF THUNDER. THE RAIN ACTIVITY THROUGH THE NIGHT WILL MAINLY COME FROM INCREASING ISENTROPIC LIFT ASSOCIATED WITH WARM AIR ADVECTION OVER THE COOL SURFACE BOUNDARY LAYER. MUCH LATER TONIGHT...LIFT FROM THE APPROACHING UPPER LEVEL LOW WILL BEGIN TO SPREAD OVER THE REGION AND WILL LIKELY SEE AN INCREASE IN CONVECTIVE/THUNDERSTORM ACTIVITY DURING THE OVERNIGHT HOURS. AS THE UPPER LEVEL LOW APPROACHES THE TEXAS PANHANDLE OVERNIGHT...A LINE OF STORMS IS EXPECTED TO DEVELOP ALONG THE PACIFIC FRONT AND SWEEP EAST ACROSS THE REGION. THE LATEST HI-RES AND SHORT TERM GUIDANCE IS NOW SLOWER WITH THE DEVELOPMENT AND MOVEMENT OF THIS LINE OF STORMS...THUS MADE MINOR ADJUSTMENTS TO POPS TOMORROW BASED ON THIS SLOWER TIMING. MOST SHORT-TERM GUIDANCE HAS THE FRONT/LINE OF STORMS ALONG OUR WESTERN BORDER AROUND 11Z/5 AM CST...GIVE OR TAKE AN HOUR. THIS WOULD PUT THE LINE OF STORMS ALONG THE I-35 CORRIDOR AROUND MID MORNING AND THEN MOVING OUT OF OUR EASTERN COUNTIES AROUND MIDDAY. WITH GOOD AGREEMENT AMONG MANY OF THE MODELS ON THIS SLOWER TIMING...CONFIDENCE IS FAIRLY HIGH THAT THE SYSTEM WILL TAKE SLIGHTLY LONGER TO ARRIVE THAN PREVIOUSLY THOUGHT...ESPECIALLY WITH THE UPPER LEVEL LOW STILL OUT IN ARIZONA. WITH LARGE SCALE LIFT SPREADING OVER THE AREA OVERNIGHT AND WARM AIR ADVECTION INCREASING...ALSO EXPECT SCATTERED SHOWER AND THUNDERSTORM ACTIVITY TO DEVELOP AHEAD OF THE LINE OF STORMS. LIKE THE STORMS ALONG THE FRONT...THE STORMS AHEAD OF THE FRONT WILL ALSO BE ELEVATED ABOVE THE COOLER SURFACE BOUNDARY LAYER. HOWEVER...IT IS POSSIBLE THAT SOME OF THESE EARLY STORMS COULD ALSO REACH SEVERE LIMITS...IN PARTICULAR SOUTH OF INTERSTATE 20 WHERE MUCAPE WILL BE HIGHER AND LAPSE RATES STEEPER. HOWEVER...OVERALL THE INSTABILITY OVERNIGHT IT NOT THAT GREAT AND THE ENVIRONMENT WILL LIKELY REMAIN CAPPED THROUGH MUCH OF THE NIGHT. THE GREATER SEVERE THREAT EXISTS WITH THE LINE OF STORMS DUE TO SUFFICIENT INSTABILITY /MUCAPE VALUES OVER 500 J/KG /...STRONG WIND SHEAR...AND BETTER LAPSE RATES. IN THIS PARTICULAR ENVIRONMENT...LARGE HAIL WILL BE THE MAIN THREAT BUT DAMAGING WINDS WILL ALSO BE POSSIBLE. CLOSER TO DAYBREAK...OR AROUND 6-7 AM...SOME OF THE MODELS DEVELOP SURFACE BASED CAPE UP TO 1000 J/KG IN OUR SOUTHWESTERN AND SOUTHERN COUNTIES AS THE WARM FRONT LIFTS INTO THAT AREA AND DEWPOINTS INCREASE INTO THE LOWER 60S. THE NAM IS MOST AGGRESSIVE WITH THE SURFACE BASED CAPE BUT THE SITUATION BEARS A CLOSE WATCH AS SURFACE BASED STORMS WILL POSE A TORNADO THREAT IN THIS STRONGLY SHEARED ENVIRONMENT. WILL HIGHLIGHT A LOW TORNADO THREAT THURSDAY MORNING ALONG AND SOUTH OF A LINE FROM HAMILTON TO FAIRFIELD. STRONG WEST WINDS WILL OCCUR BEHIND THE FRONT TOMORROW AFTERNOON WHICH WILL RESULT IN TEMPERATURES RECOVERING INTO THE 60S AND POSSIBLY LOWER 70S. A COLD FRONT WILL MOVE THROUGH THE REGION THURSDAY NIGHT/EARLY FRIDAY MORNING. THIS WILL RESULT IN COOLER TEMPS ON FRIDAY AND FREEZING TEMPS ACROSS MUCH OF THE REGION FRIDAY NIGHT. ANOTHER SHORTWAVE AND UPPER LEVEL TROUGH WILL SWING ACROSS THE REGION FRIDAY AND SATURDAY BUT THE MOISTURE WILL BE TOO SCOURED OUT FOR ANY ADDITIONAL RAIN WITH THIS FEATURE. WE WILL BRIEFLY WARM UP OVER THE WEEKEND BEFORE ANOTHER UPPER LEVEL SYSTEM MOVES INTO THE PLAINS AND DRIVES A FRONT THROUGH THE REGION ON MONDAY. SOUTHERLY RETURN FLOW AHEAD OF THIS SYSTEM MAY RESULT IN SOME SHOWERS AND STORMS SUNDAY AND SUNDAY NIGHT. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 42 65 33 54 32 / 70 100 5 5 0 WACO, TX 48 67 35 58 31 / 70 90 5 0 0 PARIS, TX 36 59 32 52 27 / 60 90 10 5 0 DENTON, TX 39 64 29 51 25 / 70 100 5 5 0 MCKINNEY, TX 38 64 30 52 28 / 70 100 5 5 0 DALLAS, TX 43 66 34 54 33 / 70 100 5 5 0 TERRELL, TX 41 64 34 55 30 / 60 100 5 5 0 CORSICANA, TX 46 67 37 59 32 / 60 90 10 5 0 TEMPLE, TX 48 69 36 62 33 / 80 90 5 0 0 MINERAL WELLS, TX 43 66 29 55 28 / 80 70 5 5 0 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 75/
AREA FORECAST DISCUSSION
NWS CORPUS CHRISTI TX
1042 PM CST WED FEB 20 2013 .DISCUSSION...SEE AVIATION DISCUSSION BELOW FOR THE 06Z TAF`S. && .AVIATION...OVERALL THINKING REMAINS THE SAME WITH DRIER MID/UPPER LEVELS MVG ACROSS THE AREA WHILE SHALLOW LOW LEVEL MOISTURE REMAINS IN PLACE OVERNIGHT. THIS WILL LEAD TO PREVAILING MVFR CIGS/VSBY`S AND IFR CIGS/VSBY`S BRIEFLY AT TIMES TOWARD EARLY THU MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME BY MID MORNING. A FRONTAL BDRY IS STILL EXPECTED TO MOVE THROUGH S TX FROM THE NW TO SE ON THU...LEADING TO MOD SLY WINDS TONIGHT SHIFTING TO THE SW EARLY MORNING TO N BY EARLY AFTERNOON. LLWS IS EXPECTED OVERNIGHT AS THE LLJ INCREASES TO 45-50KTS AND SFC WINDS DECREASE SLIGHTLY. WIND SPEEDS ARE EXPECTED TO GRADUALLY DIMINISH THROUGH THU AFTERNOON. && .PREV DISCUSSION... /ISSUED 941 PM CST WED FEB 20 2013/ DISCUSSION...LOWERED POPS A BIT OVER THE SOUTHERN AND WESTERN AREAS...BUT KEPT THEM PRETTY MUCH THE SAME NORTHEAST AS CONVERGENCE SHOWERS/STREAMERS STILL SEEM REASONABLE. ADJUSTED CLOUDS A BIT FOR THIS EVENING. OTHERWISE SAW NO NEED TO MAKE ANY CHANGES AT THIS TIME. TEMPERATURES ARE LOOKING GOOD AT THIS TIME...EVEN THE HOURLY TEMPERATURES. MARINE...DECIDED TO GO WITH A SCA FOR THE NORTHERN BAYS. IT WILL BE CLOSE...BUT WILL FIT BETTER WITH SURROUNDING OFFICES. RUC13 AND NAM12 ARE SHOWING WINDS GOING UP TO 20 KNOTS OR MORE OVER THAT AREA SO WILL BITE ON THAT. PREV DISCUSSION... /ISSUED 550 PM CST WED FEB 20 2013/ DISCUSSION...SEE AVIATION DISCUSSION BELOW FOR THE 00Z TAF`S. AVIATION...DRIER MID/UPPER LEVELS WILL FILTER ACROSS S TX THROUGH TONIGHT...HOWEVER LOW LEVEL MOISTURE WILL REMAIN IN PLACE THROUGH MUCH OF THE NIGHT AHD OF A COLD FRONT. A SLY LOW LEVEL JET WILL INCREASE TO 45-50KTS WHICH WILL LEAD TO A STRATUS DECK FLUCTUATING BETWEEN 800-1500FT. PATCHY FOG IS ALSO POSSIBLE BRIEFLY AHD OF THE FRONTAL BDRY TOWARD SUNRISE. ALI TO VCT MAY SEE THE VSBY DROP TO AROUND 1SM AT TIMES. MOD TO STRONG S WINDS WILL CLOCK AROUND TO THE SW AND W THROUGH EARLY TO MID MORNING BECOMING NW TO N BY LATE MORNING INTO EARLY AFTERNOON AS THE BDRY MOVS ESE ACROSS THE AREA ON THU. WINDS ARE EXPECTED TO DECREASE THROUGH THE AFTERNOON. PREV DISCUSSION... /ISSUED 412 PM CST WED FEB 20 2013/ SHORT TERM (TONIGHT THROUGH THURSDAY NIGHT)...UPPER LEVEL SHORT WAVE TROUGH WILL DEEPEN AND DEVELOP INTO CLOSED LOW AS IT DIGS FROM SOUTHERN CA AND ACROSS THE TX PANHANDLE THROUGH THE PERIOD. AS LOW PRESSURE DEEPENS OVER SOUTHWEST TEXAS...SOUTHEAST WINDS WILL CONTINUE TO INCREASE ACROSS THE REGION TONIGHT. ADDITIONALLY...A STRONG LLJ OF 40 TO 50KTS WILL DEVELOP OVER THE EASTERN TWO THIRDS OF THE REGION THIS EVENING AND MOVE EASTWARD ACROSS THE COASTAL WATERS TONIGHT. EXPECTING WINDS TO MIX TO THE SURFACE...AND MODERATE TO STRONG ONSHORE FLOW TO DEVELOP ACROSS THE WATERS. DUE TO THE ELEVATED WINDS AND WIDESPREAD CLOUD COVER...KEPT MINIMUM TEMPERATURES ON THE WARMER SIDE TONIGHT. THURSDAY A FRONTAL BOUNDARY WILL APPROACH FROM THE NORTHWEST...ENTERING THE REGION BY NOON...AND STALL OFFSHORE THURSDAY EVENING. DRY AIR WILL MOVE IN BEHIND THE FRONT AND LOW TEMPERATURES WILL BE MUCH COOLER THAN THE NIGHT BEFORE. AS FOR POPS...MODELS ARE NOW SHOWING MOST OF THE PRECIPITATION OCCURRING TO THE NORTHEAST OF THE REGION. DID KEEP CHANCE POPS AROUND THE VICTORIA CROSSROADS AND SLIGHT CHANCE ACROSS MUCH OF THE REGION...BUT NOT EXPECTING TO GET MUCH OF ANYTHING WIDESPREAD. LONG TERM (FRIDAY THROUGH WEDNESDAY)...THE EXTENDED FORECAST HAS CHANGED LITTLE WITH THE 12Z MODEL RUNS. FRIDAY WILL BEGIN WITH HIGH PRESSURE SURGING INTO THE REGION WITH DRIER AIR ADVECTING INTO SOUTH TEXAS. WILL KEEP SLIGHT CHANCE TO LOW END CHANCE OF SHOWERS OVER THE COASTAL WATERS FRIDAY MORNING WHERE LEFT OVER MOISTURE OVERRUN THE STALLED FRONTAL BOUNDARY. TEMPERATURES WILL BE WARM DURING THE AFTERNOON ON FRIDAY WITH THE LACK OF COLD AIR ADVECTION ASSOCIATED WITH THE SURFACE HIGH PRESSURE. FRIDAY NIGHT INTO SATURDAY MORNING WILL BE COOL...GENERALLY IN THE 40S AND 50S WITH WINDS BECOMING LIGHT. THE SURFACE RIDGE IS PULLED EASTWARD AND MOVES AWAY FROM SOUTH TEXAS WITH A WEAK RETURN FLOW DEVELOPING THROUGH THE WEEKEND. THERE MAY BE ENOUGH MOISTURE RETURN ACROSS THE REGION FOR ISOLATED SHOWERS AHEAD OF OUR NEXT BOUNDARY ON SUNDAY. A MID/UPPER LEVEL TROUGH WILL SWEEP THROUGH THE CENTRAL PLAINS AND DRIVE THE FRONT THROUGH SOUTH TEXAS MONDAY MORNING. THIS WILL ONCE AGAIN BRING NORTHERLY WINDS AND DRIER CONDITIONS BACK ACROSS SOUTH TEXAS. AGAIN...JUST A SLIGHT DROP IN AFTERNOON TEMPERATURES BEHIND THIS BOUNDARY...WITH COOLER OVERNIGHT LOWS INTO TUESDAY MORNING. ONSHORE FLOW RESUMES AGAIN TUESDAY INTO WEDNESDAY OF NEXT WEEK. OUR THIRD FRONTAL BOUNDARY IN LINE WILL BE POSSIBLE IN THE MIDDLE OF THE NEXT WEEK. FIRE WEATHER... A FRONTAL BOUNDARY APPROACHING FROM THE NORTHWEST TOMORROW WILL BRING STRONG WINDS AND LOW RELATIVE HUMIDITIES TO THE RIO GRANDE PLAINS AND BRUSH COUNTRY. NORTHWEST WINDS WILL RANGE FROM 15 TO 25 MPH WITH GUSTS UP TO 30 MPH AND MINIMUM RELATIVE HUMIDITY VALUES WILL FALL BETWEEN 15 TO 20 PERCENT DURING THE AFTERNOON. THIS WILL CREATE POSSIBLE CRITICAL FIRE WEATHER CONDITIONS FOR THE AREA...AND A RED FLAG WARNING HAS BEEN ISSUED FOR THURSDAY FROM 9AM TO 3PM. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 68 83 57 78 49 / 20 10 10 10 10 VICTORIA 64 79 50 71 43 / 40 40 10 10 10 LAREDO 65 84 51 79 52 / 10 10 10 0 0 ALICE 67 85 54 78 48 / 10 10 10 10 10 ROCKPORT 68 78 58 72 50 / 30 20 10 20 10 COTULLA 61 79 47 77 46 / 10 10 10 10 0 KINGSVILLE 66 85 53 78 47 / 10 10 10 10 10 NAVY CORPUS 68 81 60 75 54 / 20 10 20 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...RED FLAG WARNING FROM 9 AM TO 3 PM CST THURSDAY FOR THE FOLLOWING ZONES: DUVAL...LA SALLE...MCMULLEN...WEBB. GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST THURSDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS OUT 20 NM...COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM BAFFIN BAY TO PORT ARANSAS FROM 20 TO 60 NM...WATERS FROM PORT ARANSAS TO MATAGORDA SHIP CHANNEL FROM 20 TO 60 NM. SMALL CRAFT ADVISORY UNTIL 3 AM CST THURSDAY FOR THE FOLLOWING ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT ARANSAS... BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT O`CONNOR. && $$ TE/81...AVIATION
AREA FORECAST DISCUSSION
NWS SPOKANE WA
415 PM PST Fri Feb 22 2013 .SYNOPSIS...An upper level trough will move through the Pacific Northwest tonight and exit the region early Saturday morning. Pacific Northwest today and tonight. This will result in windy conditions and moderate snow in the mountains. Mountain snow showers will likely linger into Saturday afternoon. A short break in the active weather is expected Saturday night and Sunday, before the next in a series of frontal systems brings increasing chances for rain and snow to the region on Monday. This active late winter weather pattern will continue through the next week. && .DISCUSSION... Updates to hopefully better address the complex snow level and resulting accumulation or not of the snow at lower levels. Until the back edge of cold front passes it appears the more intense snowfall along and slightly ahead of the front is intense enough to insulate some of the more sheltered north aspects and edges of roadways resulting in slush while middle of roads have snow-melt ponded in them...generally all in the high impact 1900-2500 ft elevation layer where much of the public live and move about. Once the back edge of the cold front moves through the air-mass is cold enough to allow snow levels to fall much closer to just about all valley floors in the forecast area. Additionally the upper level winds are blowing about quite robustly at ridge-tops primarily southeasterly and southerly ahead of the passing cold front and should make the shift to southwest with the cold front passage and the surface low associated with it eventually positioned in vicinity of Southern Alberta near 6Z this evening. As such will likely make numerous adjustments to the grids that may have little to no impact on the text based products as this 12 hour period is so cluttered with changing weather. Will likely utilize the latest HRRR experimental model in addition to the radar and satellite to make these adjustments. /Pelatti && .AVIATION... 18Z TAFS: Local radar shows the warm front moving through my eastern zones at 0930 and will continue to push east through the remainder of the morning. Low clouds and moderate snow will result in mountain obscurations the remainder of the afternoon. Further west Rain and snow showers will continue to form and push east across the basin and into the eastern highlands through the afternoon resulting in varying conditions. A cold front will approach from the west with fropa at KEAT between 23z-01z and KGEG between 03z-06z. All TAF sites will see a 2-3 hour period of heavier precipitation and mainly as rain. Conditions are expected to dry out behind the front. Expect increasing pre-frontal winds out of the south-southwest through the afternoon with peak winds with and just behind fropa this afternoon and evening. Sustained winds of 15-20kts with gusts 25-30kts will be likely at all TAF sites through at least 12z. /Tobin && .PRELIMINARY POINT TEMPS/POPS... Spokane 29 40 25 36 29 39 / 60 20 10 20 30 70 Coeur d`Alene 30 38 26 36 30 38 / 100 30 10 20 30 70 Pullman 31 40 26 39 29 41 / 100 50 20 20 30 70 Lewiston 35 48 31 46 33 48 / 50 50 20 10 10 60 Colville 28 42 24 39 29 40 / 30 20 10 20 50 70 Sandpoint 29 38 25 35 30 36 / 100 50 10 30 40 70 Kellogg 29 37 26 34 28 37 / 100 80 20 30 30 60 Moses Lake 30 50 27 46 32 47 / 10 10 0 10 50 30 Wenatchee 30 47 28 43 31 43 / 10 10 0 10 40 30 Omak 23 40 19 35 25 38 / 10 10 0 10 50 60 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Storm Warning until 7 PM PST Saturday for Central Panhandle Mountains. Wind Advisory until 4 PM PST Saturday for Coeur d`Alene Area- Idaho Palouse. Winter Weather Advisory until 7 PM PST Saturday for Lewis and Southern Nez Perce Counties. Winter Storm Warning until 10 PM PST this evening for Northern Panhandle. WA...Winter Weather Advisory until 10 AM PST Saturday for East Slopes Northern Cascades. Wind Advisory until 4 PM PST Saturday for Lower Garfield and Asotin Counties-Spokane Area-Upper Columbia Basin- Washington Palouse. Winter Storm Warning until 10 PM PST this evening for Northeast Mountains. Winter Storm Warning until 7 PM PST Saturday for Northeast Blue Mountains. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
540 PM CST FRI FEB 22 2013 .SHORT TERM... 540 PM CST FRI FEB 22 2013 WILL ALLOW THE WINTER WEATHER ADVISORY FOR CLARK AND TAYLOR COUNTY TO EXPIRE AT 6 PM. STILL EXPECT SOME LIGHTER SNOW ACROSS TAYLOR COUNTY OVER THE NEXT HOUR...BUT VISIBILITIES AT KMDZ HAVE BEEN IMPROVING. CALLS TO CLARK COUNTY SHERIFFS DEPARTMENT SAID THE SNOW HAD ENDED AT NEILLSVILLE AROUND 4 PM. MODELS SUGGEST STILL SOME PERIODS OF LIGHT SNOW OR FLURRIES THROUGH THE EVENING HOURS OVER THOSE AREAS AND EVEN FURTHER SOUTH. HOWEVER ANY ACCUMULATIONS WILL BE MINOR AS SYSTEM PULLS NORTHEAST. .LONG TERM...MONDAY NIGHT THROUGH THURSDAY 318 PM CST FRI FEB 22 2013 22.12 MEDIUM RANGE MODELS IN SLIGHTLY BETTER AGREEMENT TODAY REGARDING THE TRACK OF THE STRONG UPPER LOW MONDAY NIGHT INTO TUESDAY. THE GFS AND ECMWF BRINGING ACCUMULATING SNOW TO THE FORECAST AREA WHILE THE GEM TAKES THE LOW WELL SOUTH OF THE FORECAST AREA. THE GFS AND ECMWF TAKE THE LOW ACROSS CENTRAL ILLINOIS ON TUESDAY AND INTO LOWER MICHIGAN TUESDAY NIGHT. THE GEM TAKES THE LOW UP THE OHIO RIVER VALLEY. MEANWHILE...THE NAM OFFERS A VERY SIMILAR SOLUTION TO THE GEM. UNCERTAINTY REMAINS ON THE TRACK OF THE STORM. DECIDED TO LEAN TOWARD THE ECMWF AND GFS SINCE THE ECMWF TENDS TO HAVE A BETTER TRACK RECORD WITH THE SYSTEMS FURTHER OUT IT IN TIME...INCREASING PRECIPITATION CHANCES ACROSS NORTHEAST IOWA INTO SOUTHWEST AND CENTRAL WISCONSIN. WILL HAVE TO MAINTAIN A CLOSE WATCH ON THIS SYSTEM SINCE IT HAS THE POTENTIAL TO PRODUCE SIGNIFICANT SNOWFALL. CHANCES FOR LIGHT SNOW ARE EXPECTED TO LINGER WEDNESDAY INTO THURSDAY AS THE LOW PUSHES INTO THE EASTERN GREAT LAKES AND STALLS. && .AVIATION...TONIGHT AND SATURDAY 540 PM CST FRI FEB 22 2013 SURFACE LOW NOW OVER EAST CENTRAL WISCONSIN WILL CONTINUE TO LIFT NORTHEAST AWAY FROM THE TAF SITES. CYCLONIC FLOW CONTINUES OVER THE AREA WITH MVFR CLOUDS ROTATING SOUTHEASTWARD OUT OF CENTRAL MINNESOTA. SOME LIGHT SNOW ALSO STILL BEING REPORTED IN THESE CLOUDS. 22.20Z HRRR SHOWS THIS AREA OF LIGHT SNOW TO DIMINISH SOMEWHAT AS IT ROTATES SOUTHEAST AND THUS HAVE ONLY MENTIONED FLURRIES AT BOTH SITES THIS EVENING. SOME QUESTION AS TO VISIBILITIES AND CEILINGS HEIGHTS. BOTH THE HRRR AND NAM BUFKIT SOUNDINGS SHOWING SOME LOW LEVEL MOISTURE UNDER THE INVERSION AND EVEN HINTS AT THE POSSIBILITY OF SOME IFR CEILINGS...ESPECIALLY AT KRST. BASED ON UPSTREAM OBSERVATIONS WILL KEEP LOWER END MVFR CEILINGS IN THE FORECAST ALONG WITH MVFR VISIBILITIES. CYCLONIC FLOW DOES WEAKEN LATER SATURDAY AND WILL LIKELY GET A RISE IN THE CEILING HEIGHTS AND PERHAPS EVEN SOME BREAKS IN THE CLOUDS BEFORE 00Z. && .ARX WATCHES/WARNINGS/ADVISORIES... 540 PM CST FRI FEB 22 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...RABERDING LONG TERM...WETENKAMP AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1144 AM CST THU FEB 21 2013 .SHORT TERM...TODAY 921 AM CST THU FEB 21 2013 QUICK UPDATE TO THE FORECAST TO ACCOUNT FOR STRATUS DECK THAT HAS FORMED ACROSS CENTRAL AND EASTERN WISCONSIN THIS MORNING. THIS HAS NOW PUSHED WEST INTO THE FORECAST AREA...AND 21.12Z NAM AND 21.13Z RAP CAPTURE THE LOW LEVEL SATURATION VERY WELL...BRINGING IT AROUND THE MISSISSIPPI RIVER IN THE LATE MORNING...THEN ACROSS MOST OF THE AREA BY EARLY AFTERNOON. THE SATURATION IS OCCURRING IN THE DENDRITIC GROWTH ZONE GIVEN THE COLD TEMPERATURES THIS MORNING SO LIGHT SNOW / FLURRIES ARE BEING REPORTED AS WELL. THIS WILL PERSIST FOR MUCH OF THE LATE MORNING AND AFTERNOON HOURS. VISIBILITY REDUCTIONS HAVE BEEN AS LOW AS 2 MILES...BUT MAINLY IN THE 4 TO 6 MILE RANGE. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 303 AM CST THU FEB 21 2013 21.00Z GFS/ECMWF SHOW A RIDGE OF HIGH PRESSURE DRIFTING ACROSS THE REGION SATURDAY NIGHT THROUGH SUNDAY FOR A BRIEF DRY/QUIET PERIOD. LOWS SATURDAY NIGHT ARE EXPECTED TO DROP INTO THE SINGLE DIGITS/LOWER TEENS ABOVE ZERO WITH HIGHS ON SUNDAY RIGHT AROUND NORMAL IN THE MIDDLE 20S TO LOWER 30S. ATTENTION THEN TURNS TO THE NEXT STORM SYSTEM TO AFFECT THE AREA SUNDAY NIGHT THROUGH WEDNESDAY. THIS SYSTEM LOOKS LIKE IT WILL GIVE THE AREA ANOTHER SHOT OF LONG DURATION ACCUMULATING SNOW WITH PERHAPS A MIX OF RAIN/SNOW IN THE SOUTH DURING THE DAY MON/TUE AS SURFACE TEMPERATURES WARM A DEGREE OR TWO ABOVE THE FREEZING MARK. MODELS PRETTY CLOSE...BUT STILL A BIT AT ODDS WITH THE EXACT TRACK OF THE LOW. THIS WILL OF COURSE DETERMINE THE EXACT OUTCOME OF ACCUMULATING SNOW AMOUNTS...DEFINITELY SOMETHING TO KEEP AN EYE ON. && .AVIATION...THROUGH 18Z FRIDAY 1144 AM CST THU FEB 21 2013 CONDITIONS TO DETERIORATE AT KRST/KLSE TONIGHT AS A WINTER STORM LIFTS TO THE REGION. THERE WILL BE SOME INITIAL DRY AIR AND SATURATION ISSUES TO OVERCOME...BUT BY 04Z A BAND OF MODERATE SNOW WILL IMPACT THE TAF SITES. SNOW RATES WITH THIS BAND LOOK TO BE BETWEEN 1/2 AND 1 INCH PER HOUR. VISIBILITY AND CEILINGS WILL RAPIDLY DROP TO LIFR...WITH THE WORST CONDITIONS EXPECTED BETWEEN 06Z AND 13Z FRIDAY. BY FRIDAY MORNING...3 TO 5 INCHES WILL HAVE ACCUMULATED...HOWEVER SNOW WILL LINGER FOR MUCH OF THE DAY. ADDITIONAL DAYTIME ACCUMULATIONS OF 2 TO 3 INCHES ARE EXPECTED AND FLIGHT CONDITIONS WILL REMAIN IN LIFR THROUGH AT LEAST 18Z. EASTERLY WINDS AROUND 10 KTS WILL PERSIST FOR THE ENTIRE PERIOD. THE SNOW WILL DIMINISH LATE FRIDAY AFTERNOON LEADING TO SLOWLY IMPROVING CONDITIONS. && .ARX WATCHES/WARNINGS/ADVISORIES... 303 AM CST THU FEB 21 2013 WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR WIZ041-053>055-061. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST FRIDAY FOR WIZ017-029-032>034-042>044. MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR MNZ079-086>088-094>096. IA...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR IAZ008>010-018-019-029-030. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR IAZ011. && $$ SHORT TERM...ZT LONG TERM...DAS AVIATION...ZT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
921 AM CST THU FEB 21 2013 .SHORT TERM...TODAY 921 AM CST THU FEB 21 2013 QUICK UPDATE TO THE FORECAST TO ACCOUNT FOR STRATUS DECK THAT HAS FORMED ACROSS CENTRAL AND EASTERN WISCONSIN THIS MORNING. THIS HAS NOW PUSHED WEST INTO THE FORECAST AREA...AND 21.12Z NAM AND 21.13Z RAP CAPTURE THE LOW LEVEL SATURATION VERY WELL...BRINGING IT AROUND THE MISSISSIPPI RIVER IN THE LATE MORNING...THEN ACROSS MOST OF THE AREA BY EARLY AFTERNOON. THE SATURATION IS OCCURRING IN THE DENDRITIC GROWTH ZONE GIVEN THE COLD TEMPERATURES THIS MORNING SO LIGHT SNOW / FLURRIES ARE BEING REPORTED AS WELL. THIS WILL PERSIST FOR MUCH OF THE LATE MORNING AND AFTERNOON HOURS. VISIBILITY REDUCTIONS HAVE BEEN AS LOW AS 2 MILES...BUT MAINLY IN THE 4 TO 6 MILE RANGE. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 303 AM CST THU FEB 21 2013 21.00Z GFS/ECMWF SHOW A RIDGE OF HIGH PRESSURE DRIFTING ACROSS THE REGION SATURDAY NIGHT THROUGH SUNDAY FOR A BRIEF DRY/QUIET PERIOD. LOWS SATURDAY NIGHT ARE EXPECTED TO DROP INTO THE SINGLE DIGITS/LOWER TEENS ABOVE ZERO WITH HIGHS ON SUNDAY RIGHT AROUND NORMAL IN THE MIDDLE 20S TO LOWER 30S. ATTENTION THEN TURNS TO THE NEXT STORM SYSTEM TO AFFECT THE AREA SUNDAY NIGHT THROUGH WEDNESDAY. THIS SYSTEM LOOKS LIKE IT WILL GIVE THE AREA ANOTHER SHOT OF LONG DURATION ACCUMULATING SNOW WITH PERHAPS A MIX OF RAIN/SNOW IN THE SOUTH DURING THE DAY MON/TUE AS SURFACE TEMPERATURES WARM A DEGREE OR TWO ABOVE THE FREEZING MARK. MODELS PRETTY CLOSE...BUT STILL A BIT AT ODDS WITH THE EXACT TRACK OF THE LOW. THIS WILL OF COURSE DETERMINE THE EXACT OUTCOME OF ACCUMULATING SNOW AMOUNTS...DEFINITELY SOMETHING TO KEEP AN EYE ON. && .AVIATION...TODAY AND TONIGHT 515 AM CST THU FEB 21 2013 VFR CONDITIONS WILL PREVAIL THROUGH THE LATE AFTERNOON AS HIGH PRESSURE SLOWLY DRIFTS AWAY FROM THE REGION. A WINTER STORM ADVANCING NORTHEAST OUT OF THE SOUTHERN PLAINS STATES WILL BRING A ROUND OF SNOW TO THE AREA TONIGHT. PLENTY OF FORCING WITH THIS SYSTEM WITH THE 21.06Z NAM SHOWING UP TO 30 PVU/S OF VORTICITY ADVECTION IN THE 500-300 MB LAYER AND A COUPLE BANDS OF WEAK TO MODERATE FRONTOGENESIS IN THE 850-500 MB LAYER. THE HIGH PRESSURE WILL LEAVE PLENTY OF DRY AIR IN PLACE WITH CONDENSATION PRESSURE DEFICITS OF 200+ MB ON THE 280K ISENTROPIC SURFACE. THE INITIAL UP GLIDE OF 2 TO 5 UBAR/S WILL GO INTO SATURATING THIS DRY LAYER WITH TOTAL SATURATION EXPECTED TO OCCUR AT THE TAF SITES BETWEEN 22.03Z AND 22.06Z. INTERESTING TO NOTE THAT THE NAM BUFKIT SOUNDINGS FOR BOTH SITES SHOWS A MVFR DECK DEVELOPING EARLY IN THE EVENING AS THE DRY AIR BECOMES CONFINED TO THE 900-700 MB LAYER. LOOKING DOWN STREAM INTO KANSAS...THERE IS A MVFR DECK WELL OUT AHEAD OF THE MAIN PRECIPITATION SHIELD SO HAVE INCLUDED THIS. EXPECTING LIGHT SNOW WITH MVFR VISIBILITIES TO DEVELOP DURING THE MID EVENING AND ONCE THE COLUMN TOTALLY SATURATES UP...THE VISIBILITY AND CEILINGS WILL GO DOWN TO IFR AND THEN STAY THERE OVERNIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... 303 AM CST THU FEB 21 2013 WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR WIZ041-053>055-061. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST FRIDAY FOR WIZ017-029-032>034-042>044. MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR MNZ079-086>088-094>096. IA...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR IAZ008>010-018-019-029-030. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR IAZ011. && $$ SHORT TERM...ZT LONG TERM...DAS AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1132 PM CST WED FEB 20 2013 .SHORT TERM...TONIGHT THROUGH SATURDAY 232 PM CST WED FEB 20 2013 FORECAST CONCERNS ARE ON WINTER STORM IMPACTING THE AREA THURSDAY NIGHT INTO FRIDAY. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A COMPLEX PATTERN ACROSS THE CONUS TODAY. AN UPPER LOW WAS LOCATED OVER NEW ENGLAND WHILE ANOTHER WAS MOVING INTO SOUTHERN CALIFORNIA. AN UPPER RIDGE EXTENDED FROM THE MID MISSISSIPPI RIVER VALLEY NORTH THROUGH THE UPPER MIDWEST. THE UPPER LOW OVER SOUTHERN CALIFORNIA WILL BE THE MAIN FEATURE TO WATCH CLOSELY TONIGHT AS IT MOVES THROUGH ARIZONA AND NEW MEXICO OVERNIGHT...EJECTING INTO THE CENTRAL PLAINS ON THURSDAY. THE LOW WILL LIFT NORTHEAST THROUGH SOUTHEAST NEBRASKA EARLY FRIDAY EVENING. AHEAD OF THE APPROACHING LOW...STRONG ISENTROPIC LIFT WILL MOVE MOVE INTO THE FORECAST AREA ON THE 280-310 K SURFACES DURING THE EVENING HOURS ON THURSDAY LEADING TO THE DEVELOPMENT OF SNOW. IMPRESSIVE LIFT NOTED IN THE DENDRITIC GROWTH ZONE THURSDAY EVENING INTO LATE THURSDAY NIGHT...WITH LIFT OF -20 UBAR/S NOTED AT -15C. THE ONLY NEGATIVE WITH THIS SYSTEM IS THAT THE INGREDIENTS FOR HEAVY SNOW FALL ADVECT NORTHEAST THROUGH THE FORECAST AREA VERY QUICKLY DURING THE OVERNIGHT HOURS. HOWEVER...MOST ARES WILL SEE A PERIOD OF HEAVY SNOWFALL WITH ACCUMULATION RATES OF 1 TO 1.5 INCHES PER HOUR. SNOW ACCUMULATIONS BY 12Z FRIDAY ARE EXPECTED TO RANGE FROM 5 TO 7 INCHES ACROSS MUCH OF NORTHEAST IOWA. LOCATIONS OVER SOUTHEAST MINNESOTA AND SOUTHWEST THROUGH CENTRAL WISCONSIN ARE EXPECTED TO SEE SNOW ACCUMULATIONS OF 3 TO 6 INCHES. THE BULK OF THE SNOW WILL FALL DURING THE OVERNIGHT HOURS THROUGH THE FRIDAY MORNING COMMUTE...LEADING TO TRAVEL IMPACTS. HAVE ISSUED A WINTER STORM WARNING FOR MOST OF NORTHEAST IOWA...EXCLUDING ALLAMAKEE COUNTY...AND HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE REST OF THE FORECAST AREA. SEE WATCH/WARNING/ADVISORIES SECTIONS BELOW FOR SPECIFIC TIMING. SNOWFALL AMOUNTS HAVE TRENDED SLIGHTLY LESS IN THE 12Z GUIDANCE AND THIS MAKES SENSE GIVEN THE PROGRESSIVE NATURE OF THE HEAVY SNOWFALL INGREDIENTS. THE LOW WILL LIFT NORTHEAST DURING THE DAY ON FRIDAY AND IS EXPECTED TO BE LOCATED OVER SOUTH CENTRAL MINNESOTA BY MIDDAY FRIDAY. LIGHT SNOW LOOKS TO PERSIST INTO FRIDAY AFTERNOON WITH ADDITIONAL ACCUMULATIONS OF 1 TO 2 INCHES POSSIBLE. THE SNOW WILL TAPER OFF SOUTH AND WEST OF INTERSTATE 94 THROUGH THE AFTERNOON HOURS AND PERSIST NORTH OF I-94 INTO FRIDAY EVENING. WILL HAVE TO KEEP A CLOSE EYE ON FREEZING DRIZZLE POTENTIAL OVER SOUTHWEST INTO CENTRAL WISCONSIN AS ICE IS LOST ALOFT LATE FRIDAY MORNING INTO EARLY FRIDAY AFTERNOON. OTHERWISE...HIGH PRESSURE WILL BE IN CONTROL TONIGHT INTO THURSDAY MORNING PROVIDING COOL AND QUIET CONDITIONS. HIGH CLOUDS WILL BE ON THE INCREASE FROM THE SOUTHWEST AHEAD OF THE APPROACHING SYSTEM. LOOK FOR LOWS TONIGHT TO RANGE FROM THE SINGLE DIGITS BELOW ZERO ACROSS NORTH CENTRAL WISCONSIN TO THE SINGLE DIGITS ABOVE ZERO OVER NORTHEAST IOWA. THE LOW WILL LIFT INTO UPPER MICHIGAN EARLY ON SATURDAY AS WEAK HIGH PRESSURE BUILDS INTO THE FORECAST AREA. MOSTLY CLOUDY SKIES ARE EXPECTED ACROSS THE FORECAST AREA ON SATURDAY UNDER THE INFLUENCE OF WEAK CYCLONIC FLOW IN THE WAKE OF THE DEPARTING LOW. LIGHT SNOW COULD LINGER ACROSS NORTH CENTRAL WISCONSIN DURING THE DAY. HIGHS ON SATURDAY WILL RANGE FROM THE MID 20S OVER CENTRAL WISCONSIN TO THE LOWER 20S OVER SOUTHEAST MINNESOTA. A VIGOROUS TROUGH WILL MOVE THROUGH THE PACIFIC NORTHWEST ON SATURDAY...DIVING INTO THE CENTRAL ROCKIES SATURDAY NIGHT. THIS SYSTEM IS THE NEXT FEATURE TO KEEP A CLOSE EYE ON. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 232 PM CST WED FEB 20 2013 20.12 MEDIUM RANGE MODELS ARE IN REASONABLE SATURDAY NIGHT THROUGH SUNDAY SHOWING THE TROUGH PUSHING INTO THE CENTRAL ROCKIES BY SUNDAY AFTERNOON. MEANWHILE...RIDGING WILL BUILD OVER THE UPPER MISSISSIPPI RIVER VALLEY PROVIDING PARTLY SUNNY SKIES ON SUNDAY. HIGHS ON SUNDAY ARE EXPECTED TO RANGE FROM THE LOWER 30S OVER CENTRAL WISCONSIN TO THE UPPER 20S OVER NORTHEAST IOWA. THE TROUGH IS EXPECTED TO MOVE EAST OUT OF THE ROCKIES AND INTO THE CENTRAL PLAINS AND DEEPENING INTO A STRONG UPPER LOW. MODEL SOLUTIONS START TO DIVERGE SLIGHTLY MONDAY INTO TUESDAY. THE 20.00 ECMWF TAKES THE LOW ACROSS EASTERN KANSAS THROUGH NORTHERN MISSOURI MONDAY NIGHT AND INTO NORTHERN ILLINOIS BY EARLY TUESDAY MORNING. THE GFS HAS A SLIGHTLY MORE NORTHERLY TRACK. THIS SYSTEM WILL BRING WARMER AIR WITH IT AND THE POTENTIAL FOR A RAIN AND SNOW MIX. THIS SYSTEM HAS THE POTENTIAL TO BRING SIGNIFICANT SNOWFALL TO THE REGION BUT THE EXACT TRACK IS UNCERTAIN AND WILL BE PINNED DOWN OVER THE NEXT FEW MODEL RUNS. THE 20.00 ECMWF LIFTS THE LOW NORTH INTO EASTERN UPPER MICHIGAN BY WEDNESDAY MORNING WHILE THE GFS TAKES IT TO THE EAST INTO THE OHIO RIVER VALLEY. LIGHT SNOW CHANCES WILL CONTINUE TUESDAY INTO WEDNESDAY...DEPENDING ON THE LOW TRACK. && .AVIATION...THROUGH 06Z FRIDAY 1132 PM CST WED FEB 20 2013 VFR CONDITIONS WITH HIGH CLOUDS EXPECTED THROUGH 00Z FRIDAY WITH WINDS GRADUALLY COMING AROUND TO THE EAST BUT REMAINING UNDER 10 KNOTS. BETWEEN 00Z-06Z SURFACE LOW BEGINS TO PUSH NORTHWARD OUT OF THE CENTRAL PLAINS. QUESTION WILL BE ONSET OF SNOW AS SOUNDINGS SHOW QUITE A BIT OF MID AND LOW LEVEL DRY AIR TO OVERCOME. MODELS CONSISTENT IN SHOWING SNOW TO BREAK OUT BETWEEN 02Z-04Z AT BOTH TAF SITES. ONCE THE SNOW BEGINS VISIBILITIES WILL QUICKLY LOWER INTO THE IFR CATEGORY WITH CEILINGS LOWERING INTO THE IFR TO LOWER MVFR CATEGORY. && .ARX WATCHES/WARNINGS/ADVISORIES... 232 PM CST WED FEB 20 2013 WI...WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY FOR WIZ041-053>055-061. WINTER WEATHER ADVISORY FROM MIDNIGHT THURSDAY NIGHT TO 6 PM CST FRIDAY FOR WIZ017-029-032>034-042>044. MN...WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY FOR MNZ079-086>088-094>096. IA...WINTER STORM WARNING FROM 6 PM THURSDAY TO 6 PM CST FRIDAY FOR IAZ008>010-018-019-029-030. WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY FOR IAZ011. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1259 AM EST SAT FEB 23 2013 .SYNOPSIS... A WARM FRONT IS EXPECTED TO LIFT NORTHWARD INTO SOUTHEAST GEORGIA THROUGH TONIGHT AS A WEDGE OF HIGH PRESSURE ANCHORS OVER THE CAROLINAS. A WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE FRONT ON SATURDAY THEN PUSH NORTHEAST. HIGH PRESSURE WILL BRIEFLY RETURN TO THE AREA ON SUNDAY BEFORE A WARM FRONT LIFTS NORTH ACROSS THE AREA LATE MONDAY AND MONDAY NIGHT....FOLLOWED BY THE PASSAGE OF A COLD FRONT EARLY TUESDAY. DRIER CONDITIONS ARE EXPECTED TO RETURN TO THE REGION BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SHORTLY AFTER MIDNIGHT...RAIN IS WIDESPREAD OVER THE FORECAST AREA BUT FOG PROBLEMS WERE MAINLY CONFINED TO SOME OF THE NEAR SHORE COASTAL WATERS AND PERHAPS BEACHES FROM SAVANNAH TO CHARLESTON. RAINY WEATHER WILL CONTINUE OVERNIGHT WITH SOME POCKETS OF HEAVIER DOWNPOURS AT TIMES. TEMPERATURES...PINNING DOWN TEMPERATURES REMAINS EXTREMELY DIFFICULT. THE LATEST RAP SUGGESTS THE WEDGE FRONT WILL REMAIN QUASI-STATIONARY OVER THE NEXT FEW HOURS...POSSIBLY EMERGING OFF THE LOWER SOUTH CAROLINA COAST BY DAYBREAK. WINDS REMAINED NORTH AT THE CHARLESTON AIRPORT WHICH AGREES WELL WITH THE RAP WIND FIELDS. HAVE ADJUSTED HOURLY TEMPERATURES TO BETTER MATCH THE REPOSITIONING OF THE WEDGE FRONT THROUGH SUNRISE. ALSO LOWERED LOW TEMPERATURES DOWN QUITE A BIT IN SOME AREAS AS SOME LOCALES WELL INLAND WERE ALREADY BELOW FORECASTED MINIMUMS. COULD VERY WELL SEE A HUGE SWING IN TEMPERATURES...ESPECIALLY AT THE COAST...SHOULD THE WARM FRONT PUSHING BACK INLAND QUICKER THAN EXPECTED. LOWS WILL RANGE FROM THE LOWER 40S WELL INLAND TO AROUND 60 IN THE LUDOWICI- DARIEN- HINESVILLE CORRIDOR...BUT THIS IS A HIGHLY UNCERTAIN FORECAST. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... SATURDAY AND SATURDAY NIGHT...A VERY LOW CONFIDENCE FORECAST TO START THE WEEKEND. A WEDGE FRONT WILL LIKELY BE POSITIONED SOMEWHERE ACROSS NORTHWEST PORTIONS OF THE FORECAST AREA AT THE START OF THE DAY AS A WAVE OF LOW PRESSURE DEVELOPS IN THE VICINITY OF CENTRAL GEORGIA. THE LOW WILL TRACK ALONG THE WEDGE FRONT THROUGH THE DAY AND SHIFT NORTHEAST OF THE AREA IN THE EVENING AS A TRAILING COLD FRONT SWINGS THROUGH FROM THE NORTHWEST. SHOWERS ARE EXPECTED TO BE ONGOING IN THE MORNING ACROSS NORTHWEST PORTIONS OF THE AREA...WITH THE GREATEST COVERAGE TOWARD THE MIDLANDS AND EAST-CENTRAL GEORGIA...AS A DISTURBANCE APPROACHES ALOFT AND ISENTROPIC LIFT STRENGTHENS. SOME SHOWERS SHOULD ALSO BE STREAMING INTO COASTAL SOUTH CAROLINA FROM THE ADJACENT COASTAL WATERS. THE BAND OF SHOWERS OVER THE MIDLANDS AND EAST-CENTRAL GEORGIA SHOULD SHIFT SOUTHEAST OVER THE AREA DURING THE AFTERNOON AND EARLY EVENING AS THE WAVE OF LOW PRESSURE PASSES...EVENTUALLY TAPERING OFF OVERNIGHT AS THE TRAILING COLD FRONT PUSHES OFFSHORE. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES...OR NEARLY 2 STANDARD DEVIATIONS ABOVE NORMAL...THE RAIN COULD BE HEAVY AT TIMES. THERE IS A POTENTIAL FOR SOME ISOLATED THUNDERSTORMS MAINLY IN THE AFTERNOON IN THE WARM SECTOR...WHICH SHOULD BE OVER PARTS OF SOUTHEAST GEORGIA AND COASTAL SOUTHEAST SOUTH CAROLINA. TEMPERATURES WILL BE VERY DIFFICULT TO FORECAST...WITH A VERY LARGE GRADIENT EXPECTED OVER THE AREA. WITH THE WEDGE EXPECTED TO PERSIST ACROSS FAR NORTHWEST PORTIONS OF THE AREA HIGHS THERE ARE ONLY FORECAST TO BE IN THE LOWER 50S...BUT WITHIN THE WARM SECTOR HIGHS COULD BE IN THE LOWER TO MID 70S ACROSS NORTH COASTAL GEORGIA AND AREAS CLOSER TO THE ALTAMAHA. PINNING DOWN THE EXACT POSITION OF THE WEDGE IS SO DIFFICULT THAT TEMPERATURES IN SOME AREAS COULD BE OFF BY AS MUCH AS 10 DEGREES FROM THE CURRENT FORECAST. SUNDAY...HIGH PRESSURE WILL BRIEFLY BUILD OVER THE REGION FROM THE NORTHWEST WITH RAIN-FREE CONDITIONS EXPECTED. TEMPERATURES COULD REACH HIGHS AROUND 70 WITH A DOWNSLOPE WIND COMPONENT ALOFT UNDER MOSTLY SUNNY TO PARTLY CLOUDY SKIES. SUNDAY NIGHT AND MONDAY...A WARM FRONT EXTENDING FROM A STORM SYSTEM OVER THE MID-MISSISSIPPI VALLEY WILL SLOWLY LIFT NORTHWARD TOWARD THE AREA. IT APPEARS THE WARM FRONT COULD ENTER PARTS OF SOUTHEAST GEORGIA LATE IN THE DAY ON MONDAY. STRENGTHENING ISENTROPIC ASCENT AND DEEP MOISTURE AHEAD OF THE WARM FRONT SHOULD ALLOW SCATTERED TO NUMEROUS SHOWERS TO DEVELOP FROM THE SOUTH SUNDAY NIGHT...THEN BECOME NUMEROUS TO WIDESPREAD ACROSS THE AREA ON MONDAY. SOME ISOLATED THUNDERSTORMS COULD ALSO DEVELOP ACROSS SOUTHERN AREAS LATER IN THE DAY DEPENDING ON THE TIMING OF THE FRONT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... WET CONDITIONS WILL PERSIST OVER THE FORECAST AREA THROUGH EARLY NEXT WEEK AS A SFC LOW SHIFTS ACROSS THE SOUTHEAST. CONDITIONS WILL THEN BEGIN TO DRY AS THE SFC LOW SHIFTS OFF THE MID ATLANTIC COAST AND IS FOLLOWED BY HIGH PRESSURE OVER THE SOUTHEAST. A COOL AND DRY TREND SHOULD THEN TAKE PLACE THROUGH MUCH OF NEXT WEEK AS A MID/UPPER LVL LOW BECOMES CUT OFF OVER THE NORTHEASTERN UNITED STATE. OVERALL...AFTERNOON HIGHS WILL RANGE FROM THE MID 60S ON TUESDAY TO THE UPPER 50S BY THURSDAY. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 30S/LOWER 40S ON TUESDAY TO MID 30S/LOWER 40S BY THURSDAY. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... BOTH TERMINALS WILL BE IFR OR LOWER FOR MOST OF THE NIGHT AS MORE DEEP MOISTURE AND WIDESPREAD RAINFALL CONTINUE TO TRACK UP THE COAST. DEGRADED VISIBILITIES DUE TO FOG AND RAIN ARE ALSO A POSSIBILITY AS THE WARM FRONT AND MINOR SHORTWAVE IMPULSES MOVE UP INTO THE AREA. CONDITIONS LOOK TO SLIGHTLY IMPROVE BY DAYBREAK AS THE WARM FRONT LIFTS NORTH OF KSAV AND WIND SPEEDS PICK UP...HOWEVER...MODEL SOUNDINGS ARE KEEPING THE DEEP MOISTURE IN PLACE FOR THE DAY. FORECAST SOUNDINGS FOR THIS AFTERNOON AND EVENING INDICATE CIGS WILL LOWER IF THEY EVEN MANAGE TO IMPROVE TO MVFR FOR A SHORT PERIOD. EXTENDED AVIATION OUTLOOK...IFR CONDITIONS WILL LIKELY CONTINUE OVERNIGHT SATURDAY NIGHT DUE TO LOW CEILINGS AND REDUCED VISIBILITIES BUT BEGIN TO SHOW LATE NIGHT IMPROVEMENTS AS DRIER AIR FILLS IN BEHIND A COLD FRONT PASSAGE. VFR CONDITIONS WILL PREVAIL SUNDAY...THEN MVFR OR LOWER CONDITIONS SHOULD RETURN SUNDAY NIGHT THROUGH MONDAY NIGHT. VFR CONDITIONS WILL THEN PREVAIL TUESDAY INTO WEDNESDAY. && .MARINE... SAVANNAH PILOT BOAT REPORTED VSBYS NEAR ZERO IN DENSE SEA FOG AS FAR OFFSHORE AS BUOY CHARLIE. HILTON HEAD AIRPORT ALSO REPORTING A CEILING NEAR 100 FT SUGGESTING FOG IS LIKELY NOT TOO FAR OFFSHORE. HAVE ISSUED A DENSE FOG ADVISORY FOR AMZ352-354 UNTIL 1 AM. ITS UNCLEAR HOW MUCH VSBYS WILL IMPROVE AS RAIN FILLS IN...SO ONLY TOOK THE ADVISORY UNTIL 1 AM. ADJUSTMENTS WILL BE NEEDED OVER THE NEXT FEW HRS. ADJUSTED WINDS OVER THE SOUTH CAROLINA WATERS TO NORTH OVERNIGHT AS RAP GUIDANCE SUGGESTS THE WEDGE FRONT WILL DROP SOUTH. ALSO NUDGED THE START TIME FOR THE SMALL CRAFT ADVISORY TO THE CURRENT TIME OVER THE GEORGIA OFFSHORE WATERS. SATURDAY THROUGH TUESDAY...SMALL CRAFT ADVISORY CONDITIONS WILL PERSIST OVER OUTER GEORGIA WATERS THROUGH 5 PM SATURDAY AS A WEDGE OF HIGH PRESSURE INLAND MAINTAINS AN ENHANCED PRESSURE GRADIENT OVER THESE WATERS THROUGH MUCH OF THE DAY AND SEAS REMAIN ELEVATED. THE WEDGE WILL THEN BREAK DOWN LATE AS A SFC LOW TRACKS THROUGH THE SOUTHEASTERN UNITED STATES AND INTO THE MID ATLANTIC. EXPECT SOUTHERLY WINDS TO BECOME WEST AS A TRAILING COLD FRONT SHIFTS THROUGH THE WATERS INTO EARLY SUNDAY. CONDITIONS WILL THEN REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR ALL WATERS THROUGH EARLY MONDAY AS HIGH PRESSURE DOMINANTS THE PATTERN. WINDS AND SEAS WILL THEN INCREASE MONDAY AFTERNOON INTO TUESDAY AS A WARM FRONT LIFTS NORTH AND THEN IS FOLLOWED BY A SFC LOW TRACKING OVER THE WATERS LATE. WE COULD SEE SMALL CRAFT ADVISORY CONDITIONS AS THE PRESSURE GRADIENT BECOMES ENHANCED OVER THE WATERS DURING THIS TIME. && .HYDROLOGY... STORM TOTAL RAINFALL AMOUNTS OF 3-6 INCHES WITH LOCALLY HIGHER AMOUNTS ARE LIKELY TO OCCUR ACROSS THE REGION THROUGH EARLY NEXT WEEK BRINGING MORE RELIEF TO DROUGHT STRICKEN AREAS. THESE RAINS FALLING INTO ALREADY SWOLLEN RIVERS WILL YIELD ADDITIONAL RISES AND RIVER FLOODING THROUGH THE END OF NEXT WEEK. ADDITIONAL RIVER FLOOD WARNINGS ARE LIKELY PER THE LATEST SHORT TERM ENSEMBLE HYDROLOGIC FORECASTS AND RIVER GUIDANCE FROM THE SOUTHEAST RIVER FORECAST CENTER. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...DENSE FOG ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR AMZ330-350-352-354. SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR AMZ374. && $$ SYNOPSIS... NEAR TERM... SHORT TERM...JAQ LONG TERM...DPB AVIATION... MARINE...ST HYDROLOGY...
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1041 AM CST THU FEB 21 2013 .DISCUSSION... ISSUED 1024 AM CST THU FEB 21 2013 WINTER WEATHER STORM SPINNING UP OVER MISSOURI AND ON TRACK FOR ILX THIS AFTERNOON. SOME MINOR MIX OF PRECIPITATION ON THE LEADING EDGE...BUT MAINLY SNOW EXPECTED WEST AND NORTHWEST OF THE I-55 CORRIDOR. FREEZING RAIN STILL ANTICIPATED ON THE BACK EDGE OF THE SYSTEM...AND IN THE SOUTHEAST...PARTICULARLY ALONG AND SOUTH OF A LINE ROUGHLY FROM PARIS TO TAYLORVILLE. GOING FORECAST IS ACTUALLY ON TRACK...AND CONSIDERING THE WINTRY MIX AND CURRENT VARIABLES...NO REASON TO ALTER THE FORECAST BEYOND WHAT IS CURRENTLY IN THE GRIDS SIGNIFICANTLY. HAVE ALTERED HOURLY TEMPS AND SKY COVER...BUT PRECIP TRENDS ON TRACK. MAJOR CONCERN FOR AFFECTING THE SNOW TOTAL AMOUNTS ARE TWO FOLD...ONE...THE SYSTEM WILL LIKELY BE QUICK IN PASSING AND TOTALS WILL HAVE TO ACCUMULATE QUICKLY TO MAKE AN IMPACT BEFORE THE AREA IS OVERTAKEN BY THE DRY SLOT. TWO...THOUGH THUNDER ACTIVITY IS EXPECTED TO REDUCE AS THE SYSTEM PULLS THROUGH CENTRAL IL...SOME ISOLATED THUNDER IS STILL QUITE POSSIBLE. AREAS AFFECTED BY A CONVECTIVELY ENHANCED STORM HAVE THE POTENTIAL TO SEE LOCALIZED HIGHER TOTALS. WINTER WEATHER ADVISORIES AND TIMING REMAIN UNCHANGED. HJS && .AVIATION... ISSUED 532 AM CST THU FEB 21 2013 LARGE STRATOCUMULUS DECK AROUND 2000 FEET IS ADVECTING IN FROM THE NORTHEAST...WITH AWIPS TIMING TOOLS INDICATING ARRIVAL FROM KBMI- KCMI BY AROUND 13Z. RAP MODEL HUMIDITY PLOT AT 2500 FEET LINES UP WELL...AND SUGGESTS IT SHOULD CONTINUE TOWARD KPIA AND KDEC TOWARD 16-17Z. WILL KEEP THESE MVFR CEILINGS OUT OF KSPI FOR NOW...BUT CONDITIONS THERE WILL RAPIDLY DETERIORATE EARLY THIS AFTERNOON WITH SNOW MOVING IN FROM THE SOUTHWEST TOWARD 21Z. THIS PRECIPITATION WILL OVERSPREAD THE REMAINING TAF SITES BY ABOUT 23Z...WITH IFR OR LIFR CONDITIONS BECOMING WIDESPREAD. FORECAST SOUNDINGS SHOWING SOME FREEZING RAIN POTENTIAL AT KSPI/KDEC EARLY THIS EVENING AS WELL. HEAVIEST PRECIPITATION EXPECTED THROUGH ABOUT 04-05Z...WITH A GRADUAL TREND TOWARD FREEZING DRIZZLE AT ALL TAF SITES AFTER 06Z. GEELHART && .PREV DISCUSSION... ISSUED 340 AM CST THU FEB 21 2013 WILL CONTINUE THE WINTER WEATHER ADVISORY ACROSS CENTRAL AND SOUTHEAST IL BUT START IT AT NOON IN AREAS FROM SPRINGFIELD SW AND START AT 3 PM REST OF CWA. WINTER WX ADVISORY GOES THROUGH 6 AM FRIDAY EXCEPT THROUGH NOON FRIDAY FROM LINCOLN NORTH. INCREASED ICE ACCUMULATIONS OVER SE IL TO BETWEEN A TENTH AND A QUARTER INCH AND ALSO ADDED ISOLATED THUNDERSTORMS TO SW AREAS LATE TODAY. BRUNT OF SNOW STILL EXPECTED TO DEVELOP FROM SW TO NE DURING THE AFTERNOON AND CONTINUE THIS EVENING BEFORE DIMINISHING OVERNIGHT. SNOWFALL AMOUNTS TO RANGE FROM LESS THAN 1 INCH FROM I-70 SE TO 3-5 INCHES FROM I-55 NW WITH HIGHEST AMOUNTS NW OF THE IL RIVER. BETWEEN 1 AND 3 INCHES OF SNOW OVER EAST CENTRAL IL WITH ICE ACCUMULATIONS UP TO A TENTH INCH AS FAR NORTH AS I-72. SHORT TERM...TODAY THROUGH SUNDAY STRONG 541 DM 500 MB LOW NEAR THE SOUTHERN AZ/NM BORDER THAT BROUGHT SNOW AS FAR SOUTH AS TUCSON IN SOUTHERN AZ THIS PAST NIGHT HAS 996 MB LOW PRESSURE OVER NE NM. 1042 DM 500 MB ARCTIC HIGH PRESSURE OVER NW ONTARIO AND RIDGING SOUTHWARD INTO IL AND TN VALLEY BRINGING ANOTHER COLD NIGHT WITH TEMPS IN THE MID TO UPPER TEENS CENTRAL IL AND LOWER 20S IN SE IL. MODELS EJECT UPPER LEVEL LOW NE INTO THE CENTRAL PLAINS BY THIS EVENING AND INTO WI FRI EVENING. STRONG SURFACE LOW IN NE NM TO WEAKEN AS IT EJECTS NE INTO SE KS BY THIS EVENING AND INTO NW IL BY MIDDAY FRI. MODELS HAVE TRENDED FURTHER SE WITH LOW PRESSURE TRACK AND ALSO WITH COLDER AIR. MODELS IN GOOD AGREEMENT THAT MOST OF CENTRAL/SE IL WILL STAY DRY THIS MORNING WITH SNOW SPREADING NE ACROSS AREA DURING THE AFTERNOON THOUGH NOT TO AREAS NE OF I-74 UNTIL CLOSER TO 6 PM. SLEET MIXED IN WITH SNOW FROM I-72 SOUTH WITH FREEZING RAIN POSSIBLE TOO IN SE IL ESPECIALLY LATER THIS AFTERNOON. SPC HAS CHANCE OF THUNDERSTORMS FROM I-72 SOUTH THIS AFTERNOON AND ADDED ISOLATED THUNDERSTORMS LATER THIS AFTERNOON TO SW AREAS. THIS COULD ENHANCE SNOWFALL RATES OF 1-2 INCHES PER HOURS IN A FEW CONVECTIVE BANDS THIS LATER THIS AFTERNOON AND EARLY EVENING. USED A 10-12:1 SNOW RATIO FOR THIS EVENT PER BUFKIT. MIXED PRECIPITATION TO GRADUALLY SPREAD NORTHWARD DURING TONIGHT WITH AND DIMINISH TO FREEZING DRIZZLE DURING OVERNIGHT AS WE LOSE MID LEVEL MOISTURE. AS STATED ABOVE...ICE ACCUMULATIONS UP TO A TENTH INCH AS FAR NORTH AS I-72 WITH LESS THAN A TENTH INCH NORTH OF I-72. BETWEEN A TENTH AND A QUARTER INCH OF ICE IN SOUTHEAST IL FROM I-70 SOUTH WITH HIGHEST AMOUNTS FROM EFFINGHAM AND CLAY COUNTY SW. SNOWFALL AMOUNTS LESS THAN 1 INCH FROM I-70 SE WHILE 3-5 INCHES FROM I-55 NW WITH HIGHEST AMOUNTS OF 4-6 INCHES NW BY KNOX... FULTON AND SCHUYLER COUNTIES. SOME BLOWING SNOW POSSIBLE ESPECIALLY NW AREAS WITH EAST WINDS INCREASING TO 15-20 MPH WITH GUSTS TO AROUND 30 MPH THIS AFTERNOON AND EVENING. LINGERING FREEZING DRIZZLE AND LIGHT SNOW FRIDAY NORTHERN AREAS AND CONTINUE THE WINTER WX ADVISORY THROUGH NOON FRIDAY NORTH OF I-72. SHOULD RISE ABOVE FREEZING FOR CENTRAL AND SE COUNTIES TO CHANGE ANY LINGERING PRECIPITATION TO PATCHY DRIZZLE. WEAKENING UPPER LEVEL LOW MOVES INTO MI SAT/SAT NIGHT WITH PRECIPITATION ENDING OVER CENTRAL IL AND LOW CLOUDS DECREASING. TEMPS COOLING WITH HIGHS AROUND 30F NORTH AND UPPER 30S IN SE IL SAT. DRY WEATHER CONTINUES SUNDAY WITH TEMPS MODIFYING AS UPPER LEVEL RIDGE PUSHES EAST INTO THE MS VALLEY AS WEAK SURFACE HIGH SETTLES OVER IL BY MIDDAY SUNDAY. LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY EXTENDED MODELS HAVE TRENDED A BIT COLDER WITH NEXT CUTOFF UPPER LEVEL LOW EJECTING NE FROM THE SOUTHERN ROCKIES INTO IL BY TUE MORNING. GFS APPEARS TOO FAST WITH THIS CUTOFF UPPER LEVEL LOW AND TRENDED FORECASTER TOWARD SLOWER ECMWF. BEST CHANCES OF PRECIPITATION LATER MONDAY INTO TUESDAY. MAINLY RAIN OVER SE IL WHILE MIX OF RAIN/SNOW OVER CENTRAL IL. UPPER LEVEL LOW TO LINGER OVER THE GREAT LAKES REGION MIDDLE OF NEXT WEEK AND COULD KEEP CLOUDS AROUND LONGER ALONG WITH LOW CHANCES OF LIGHT PRECIPITATION ESPECIALLY NE AREAS. STUCK CLOSE TO ALLBLEND TEMPS DURING THIS TIME WHICH IS CLOSE TO NORMAL FOR LATE FEBRUARY. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM CST FRIDAY FOR ILZ043>046-053>057-061>063-066>068-071>073. WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON CST FRIDAY FOR ILZ027>031-036>038-041-042. WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR ILZ040-047>052. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
532 AM CST THU FEB 21 2013 .DISCUSSION... ISSUED 340 AM CST THU FEB 21 2013 WILL CONTINUE THE WINTER WEATHER ADVISORY ACROSS CENTRAL AND SOUTHEAST IL BUT START IT AT NOON IN AREAS FROM SPRINGFIELD SW AND START AT 3 PM REST OF CWA. WINTER WX ADVISORY GOES THROUGH 6 AM FRIDAY EXCEPT THROUGH NOON FRIDAY FROM LINCOLN NORTH. INCREASED ICE ACCUMULATIONS OVER SE IL TO BETWEEN A TENTH AND A QUARTER INCH AND ALSO ADDED ISOLATED THUNDERSTORMS TO SW AREAS LATE TODAY. BRUNT OF SNOW STILL EXPECTED TO DEVELOP FROM SW TO NE DURING THE AFTERNOON AND CONTINUE THIS EVENING BEFORE DIMINISHING OVERNIGHT. SNOWFALL AMOUNTS TO RANGE FROM LESS THAN 1 INCH FROM I-70 SE TO 3-5 INCHES FROM I-55 NW WITH HIGHEST AMOUNTS NW OF THE IL RIVER. BETWEEN 1 AND 3 INCHES OF SNOW OVER EAST CENTRAL IL WITH ICE ACCUMULATIONS UP TO A TENTH INCH AS FAR NORTH AS I-72. SHORT TERM...TODAY THROUGH SUNDAY STRONG 541 DM 500 MB LOW NEAR THE SOUTHERN AZ/NM BORDER THAT BROUGHT SNOW AS FAR SOUTH AS TUCSON IN SOUTHERN AZ THIS PAST NIGHT HAS 996 MB LOW PRESSURE OVER NE NM. 1042 DM 500 MB ARCTIC HIGH PRESSURE OVER NW ONTARIO AND RIDGING SOUTHWARD INTO IL AND TN VALLEY BRINGING ANOTHER COLD NIGHT WITH TEMPS IN THE MID TO UPPER TEENS CENTRAL IL AND LOWER 20S IN SE IL. MODELS EJECT UPPER LEVEL LOW NE INTO THE CENTRAL PLAINS BY THIS EVENING AND INTO WI FRI EVENING. STRONG SURFACE LOW IN NE NM TO WEAKEN AS IT EJECTS NE INTO SE KS BY THIS EVENING AND INTO NW IL BY MIDDAY FRI. MODELS HAVE TRENDED FURTHER SE WITH LOW PRESSURE TRACK AND ALSO WITH COLDER AIR. MODELS IN GOOD AGREEMENT THAT MOST OF CENTRAL/SE IL WILL STAY DRY THIS MORNING WITH SNOW SPREADING NE ACROSS AREA DURING THE AFTERNOON THOUGH NOT TO AREAS NE OF I-74 UNTIL CLOSER TO 6 PM. SLEET MIXED IN WITH SNOW FROM I-72 SOUTH WITH FREEZING RAIN POSSIBLE TOO IN SE IL ESPECIALLY LATER THIS AFTERNOON. SPC HAS CHANCE OF THUNDERSTORMS FROM I-72 SOUTH THIS AFTERNOON AND ADDED ISOLATED THUNDERSTORMS LATER THIS AFTERNOON TO SW AREAS. THIS COULD ENHANCE SNOWFALL RATES OF 1-2 INCHES PER HOURS IN A FEW CONVECTIVE BANDS THIS LATER THIS AFTERNOON AND EARLY EVENING. USED A 10-12:1 SNOW RATIO FOR THIS EVENT PER BUFKIT. MIXED PRECIPITATION TO GRADUALLY SPREAD NORTHWARD DURING TONIGHT WITH AND DIMINISH TO FREEZING DRIZZLE DURING OVERNIGHT AS WE LOSE MID LEVEL MOISTURE. AS STATED ABOVE...ICE ACCUMULATIONS UP TO A TENTH INCH AS FAR NORTH AS I-72 WITH LESS THAN A TENTH INCH NORTH OF I-72. BETWEEN A TENTH AND A QUARTER INCH OF ICE IN SOUTHEAST IL FROM I-70 SOUTH WITH HIGHEST AMOUNTS FROM EFFINGHAM AND CLAY COUNTY SW. SNOWFALL AMOUNTS LESS THAN 1 INCH FROM I-70 SE WHILE 3-5 INCHES FROM I-55 NW WITH HIGHEST AMOUNTS OF 4-6 INCHES NW BY KNOX... FULTON AND SCHUYLER COUNTIES. SOME BLOWING SNOW POSSIBLE ESPECIALLY NW AREAS WITH EAST WINDS INCREASING TO 15-20 MPH WITH GUSTS TO AROUND 30 MPH THIS AFTERNOON AND EVENING. LINGERING FREEZING DRIZZLE AND LIGHT SNOW FRIDAY NORTHERN AREAS AND CONTINUE THE WINTER WX ADVISORY THROUGH NOON FRIDAY NORTH OF I-72. SHOULD RISE ABOVE FREEZING FOR CENTRAL AND SE COUNTIES TO CHANGE ANY LINGERING PRECIPITATION TO PATCHY DRIZZLE. WEAKENING UPPER LEVEL LOW MOVES INTO MI SAT/SAT NIGHT WITH PRECIPITATION ENDING OVER CENTRAL IL AND LOW CLOUDS DECREASING. TEMPS COOLING WITH HIGHS AROUND 30F NORTH AND UPPER 30S IN SE IL SAT. DRY WEATHER CONTINUES SUNDAY WITH TEMPS MODIFYING AS UPPER LEVEL RIDGE PUSHES EAST INTO THE MS VALLEY AS WEAK SURFACE HIGH SETTLES OVER IL BY MIDDAY SUNDAY. LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY EXTENDED MODELS HAVE TRENDED A BIT COLDER WITH NEXT CUTOFF UPPER LEVEL LOW EJECTING NE FROM THE SOUTHERN ROCKIES INTO IL BY TUE MORNING. GFS APPEARS TOO FAST WITH THIS CUTOFF UPPER LEVEL LOW AND TRENDED FORECASTER TOWARD SLOWER ECMWF. BEST CHANCES OF PRECIPITATION LATER MONDAY INTO TUESDAY. MAINLY RAIN OVER SE IL WHILE MIX OF RAIN/SNOW OVER CENTRAL IL. UPPER LEVEL LOW TO LINGER OVER THE GREAT LAKES REGION MIDDLE OF NEXT WEEK AND COULD KEEP CLOUDS AROUND LONGER ALONG WITH LOW CHANCES OF LIGHT PRECIPITATION ESPECIALLY NE AREAS. STUCK CLOSE TO ALLBLEND TEMPS DURING THIS TIME WHICH IS CLOSE TO NORMAL FOR LATE FEBRUARY. 07 && .AVIATION... ISSUED 532 AM CST THU FEB 21 2013 LARGE STRATOCUMULUS DECK AROUND 2000 FEET IS ADVECTING IN FROM THE NORTHEAST...WITH AWIPS TIMING TOOLS INDICATING ARRIVAL FROM KBMI- KCMI BY AROUND 13Z. RAP MODEL HUMIDITY PLOT AT 2500 FEET LINES UP WELL...AND SUGGESTS IT SHOULD CONTINUE TOWARD KPIA AND KDEC TOWARD 16-17Z. WILL KEEP THESE MVFR CEILINGS OUT OF KSPI FOR NOW...BUT CONDITIONS THERE WILL RAPIDLY DETERIORATE EARLY THIS AFTERNOON WITH SNOW MOVING IN FROM THE SOUTHWEST TOWARD 21Z. THIS PRECIPITATION WILL OVERSPREAD THE REMAINING TAF SITES BY ABOUT 23Z...WITH IFR OR LIFR CONDITIONS BECOMING WIDESPREAD. FORECAST SOUNDINGS SHOWING SOME FREEZING RAIN POTENTIAL AT KSPI/KDEC EARLY THIS EVENING AS WELL. HEAVIEST PRECIPITATION EXPECTED THROUGH ABOUT 04-05Z...WITH A GRADUAL TREND TOWARD FREEZING DRIZZLE AT ALL TAF SITES AFTER 06Z. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM CST FRIDAY FOR ILZ043>046-053>057-061>063-066>068-071>073. WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON CST FRIDAY FOR ILZ027>031-036>038-041-042. WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST FRIDAY FOR ILZ040-047>052. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
304 AM CST SAT FEB 23 2013 .SYNOPSIS... 06Z SFC ANALYSIS HAS AN OCCLUDED LOW NEARING THE MACKINAC STRAITS WHILE HIGH PRESSURE WAS ACROSS THE PLAINS. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS THE PLAINS WITH 20S AND 30S ACROSS THE GREAT LAKES AND OHIO VALLEY. && .SHORT TERM...TODAY AND TONIGHT... A COMBINATION OF CYCLONIC FLOW ALOFT AND VORT MAXES...MAINLY AT 700 MB IS PRODUCING FLURRIES/LIGHT SNOW ACROSS THE NORTHERN PART OF THE CWFA AND UP INTO MINNESOTA. THE RAP TRENDS HAVE THE 700MB SHORTWAVE ROTATING THROUGH DURING THE DAY WITH NEAR CONTINUOUS 700MB VORT MAXES ROTATING THROUGH. THUS FLURRIES/VERY LIGHT SNOW WILL BE SEEN ACROSS ROUGHLY THE NORTHERN HALF DURING THE MORNING. FCST SOUNDINGS SHOW A DRYING ALOFT OCCURRING DURING THE AFTERNOON SO ANY FLURRIES/LIGHT SNOW WILL GRADUALLY END. BASED ON 0.5KM CONDENSATION PRESSURES/WIND...CLOUDS SHOULD STAY PUT FOR MUCH OF THE MORNING BEFORE CLEARING STARTS FROM WEST TO EAST DURING THE AFTERNOON. THE COLD POOL ALOFT MAY HELP GENERATE SOME DIURNAL CLOUDS WHICH MAY SLOW THE RATE OF CLEARING DURING THE AFTERNOON HOURS. ..08.. .LONG TERM...SUNDAY THROUGH NEXT FRIDAY... THE EXTENDED STORM IS IN MUCH BETTER AGREEMENT IN MODEL FORECASTS TONIGHT...AND IS FOCUSED ON A SURFACE LOW TRACK FROM OK/AR THROUGH INDIANA MONDAY INTO TUESDAY. THE STORM SHOULD ONCE AGAIN HAVE A BROAD UPPER LOW ASSOCIATED WITH IT...AND BY IN LARGE...THE UPPER LOW SHOULD DOMINATE THE AREAL PLACEMENT OF RAIN AND SNOW. THE BIGGEST DIFFERENCE IN MODELS TONIGHT...IS THAT NO MODEL FORECASTS AN INTENSIFYING SURFACE LOW...OR EVEN A STRONG OCCLUDED LOW AS IT MOVES PAST THE REGION. THIS WOULD INDICATE A MUCH LOWER RISK FOR A STRONG WIND DRIVEN SNOW/BLIZZARD THAN THE EARLIER 12Z ECMWF WOULD HAVE INDICATED. DESPITE THIS...THE STORM SHOULD BE ABLE TO PRODUCE A HEALTHY DEFORMATION ZONE...AND ALL MODELS BRUSH THIS FORCING THROUGH THE CENTRAL AND SOUTHERN CWA...AND THIS MAY REQUIRE HEADLINES TO BE ISSUED TODAY IN OUR SOUTH. MODERATE SNOW ACCUMULATIONS OVER 3 INCHES SEEM LIKELY WITH THIS SYSTEM...AND SHOULD A DIRECT HIT FROM THE DEF ZONE OCCUR...HEAVY AMOUNTS ARE POSSIBLE. AS THE SYSTEM MOVES PAST INTO THE LOWER GREAT LAKES...MORE ENERGY IS FORECAST BY THE GFS AND ECMWF TO MOVE INTO THE WESTERN SIDE OF THE UPPER LOW...AND THIS SHOULD PRODUCE AN EXTENDED PERIOD OF LIGHT SNOW BEGINNING TUESDAY NIGHT INTO WEDNESDAY NIGHT. THE GFS IS MOST BULLISH...WITH 1 TO 2 INCHES OF SNOW FOR SEVERAL PERIODS IN A ROW FOR A LARGE AREA...WHILE THE ECMWF IS MORE CONSERVATIVE. ANY WAY YOU SHAKE IT...IT APPEARS UNSETTLED...CLOUDY...WITH LIGHT SNOW OR FLURRIES IN THE WAKE OF THE EARLY WEEK STORM...AT LEAST THROUGH WEDNESDAY NIGHT. LATE WEEK...MODELS SHOW A MUDDLED MESS OF NORTHERLY FLOW ALOFT. THERE CERTAINLY COULD BE SOME SNOW POTENTIAL THERE...BUT IF IT WOULD OCCUR...MOISTURE WOULD BE VERY LIMITED...AND AMOUNTS VERY LIGHT. TEMPERATURES WILL AGAIN BE FORECAST TO AVERAGE BELOW NORMAL ON HIGHS...MAINLY IN THE LOWER TO MID 30S THIS WEEK. LOWS IN THE TEENS TO MID 20S ARE FORECAST FROM NORTHWEST TO SOUTHEAST...WITH THE MILDEST LOWS ASSOCIATED WITH MONDAY NIGHT AND TUESDAY NIGHT AS WE SHOULD EXPERIENCE HIGHER DEWPOINTS WITH THE POTENTIAL SNOW EVENT. ERVIN && .AVIATION... MVFR/VFR CONDITIONS THROUGH AT LEAST 18Z/23 BEFORE SKIES CLEAR FROM WEST TO EAST ACROSS IOWA/ILLINOIS. A DISTURBANCE ALOFT IS EXPECTED TO KEEP A THREAT OF FLURRIES OR SHSN AT KDBQ AND POSSIBLY KCID/KMLI THROUGH AT LEAST 18Z/23. HIGH PRESSURE BUILDING INTO THE MIDWEST AFT 00Z/24 IS EXPECTED TO RESULT IN VFR CONDITIONS. ..08.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1132 PM CST FRI FEB 22 2013 .SYNOPSIS... ISSUED AT 257 PM CST FRI FEB 22 2013 SLOWLY FILLING SURFACE LOW THAT HAS MOVED NORTH ACROSS THE FORECAST AREA TODAY IS CONTINUING TO MOVE UP INTO SOUTHERN WISCONSIN...AND AS OF 2 PM WAS LOCATED WEST OF MADISON WISCONSIN...WITH A BROAD AREA OF PRESSURE FALLS OVER WISCONSIN. A VERY WEAK TROUGH AXIS EXTENDS BACK INTO NORTHERN IOWA...WHERE SNOW CONTINUES TO FALL VERY LIGHTLY. LOW CLOUDS EXTEND BACK INTO NORTHERN MISSOURI. THERE IS AN AREA IN NORTHWEST MISSOURI WHERE THE CLOUDS HAVE EITHER THINNED OR CLEARED OUT ENTIRELY AS WE CAN SEE THE TEXTURE OF THE GROUND BENEATH ON VISIBLE SATELLITE IMAGERY. THIS IS IN A OBSERVATIONAL DATA VOID AREA...SO IT IS HARD TO DETERMINE WHAT EXACTLY IS GOING ON. AT UPPER LEVELS...BROAD UPPER LEVEL TROUGH OVER THE WESTERN CONUS WITH THE STRONG SHORTWAVE OVER THE MIDWEST ASSOCIATED WITH THIS STORM SYSTEM. STRONG PRESSURE FALLS AHEAD OF THE SHORTWAVE IMPLY THAT IT WILL CONTINUE NORTHEAST...BUT SMALL RISES BEHIND IT SHOW THAT IT IS FILLING AND THE BROADER SCALE TROUGH IS STILL DEEPENING. ..LE.. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 257 PM CST FRI FEB 22 2013 THIS AFTERNOON THE SNOW BAND IS EXPECTED TO CONTINUE TO MOVE NORTHEAST OUT OF THE AREA...AND PLAN ON ALLOWING THE WINTER STORM WARNING AND ADVISORY EXPIRE HERE AT 3 PM. SOME FLURRIES WILL LIKELY STILL AFFECT THE NORTHERN THIRD OF THE FORECAST AREA WITH SOME LOW LEVEL CONVERGENCE AND LIFT GOING ON ACCORDING TO THE RUC THIS EVENING. THUS...HAVE CONTINUED THE SLIGHT CHANCE POPS THIS EVENING BUT WITH NO ACCUMULATIONS EXPECTED. TONIGHT THE SURFACE LOW EJECTS OFF TO THE NORTHEAST...AND WILL BE OVER THE UP OF MICHIGAN BY 06Z TONIGHT. THAT WILL DRAW THE LIFT AND MOST OF THE MOISTURE OFF TO THE NORTHEAST...LEAVING US WITH SOME LINGERING LOW LEVEL MOISTURE. IN FACT...ACCORDING TO SOUNDINGS WE REMAIN FAIRLY WELL SATURATED BELOW 850MB THROUGH SATURDAY MORNING. FLURRIES SHOULD BE POSSIBLE AS THE LEAST LITTLE WIGGLE IS GOING TO PRODUCE THEM. IT APPEARS THAT WE WILL BE COLD ENOUGH AT THE TOP OF THAT LAYER FOR THESE TO BE FLURRIES INSTEAD OF FREEZING DRIZZLE..BUT LATER SHIFTS WILL HAVE TO WATCH FOR THIS. UPSTREAM MIN TEMPERATURES FELL INTO THE TEENS OVER NEBRASKA AND KANSAS LAST NIGHT...SO HAVE KEPT THE MIN TEMPS IN THE TEENS OVERNIGHT. MAY BE SLIGHTLY WARMER WITH THE EXTRA CLOUD COVER...SO DID NOT BRING IN ANY SINGLE DIGIT VALUES. THE EXTRA CLOUD COVER IS ALSO GOING TO KEEP TEMPS FROM FALLING OFF VERY FAST OVERNIGHT...SO A SLOW DROP OFF IN THE EVENING IS EXPECTED. SATURDAY TO BE COLD AND QUIET WITH THE STORM OFF TO THE NORTHEAST AND A GRADUAL CLEARING TREND FROM THE SOUTH. WE ARE NOT BRINGING IN A COLD AIRMASS BEHIND THIS SYSTEM...BUT WITH THE SNOW COVER WE ARE GOING TO BE COLDER THAN WE WOULD WITHOUT. SO...EXPECT HIGHS IN THE 20S TO NEAR 30. LINGERING LOW LEVEL MOISTURE SHOULD LIFT TO AFTERNOON STRATOCUMULUS...BUT STILL ALLOWING A FAIR AMOUNT OF SUNSHINE THROUGH. ..LE.. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 257 PM CST FRI FEB 22 2013 ANOTHER MAJOR AND STRONGER WINTER STORM FOR MONDAY/TUESDAY THE MAIN FORECAST CHALLENGE. OVERVIEW...INITIALIZATION GOOD TO EXCELLENT UPSTREAM INTO THE NORTH PACIFIC. THE 18Z VERIFICATION SUPPORT ALL 4 LONGER RANGE SOLUTIONS VERIFYING WELL AND ARE ALL SIMILAR. THATS THE GOOD NEWS...UNLESS ONE LIKES LOTS OF SNOW...THEY ALL PUT AREA IN THE WHEELHOUSE OF A MAJOR WINTER STORM WITH STRONG WINDS. PREFER A BLEND OF ALL 4 AS A MIX WHICH SUPPORTS MOST OR ALL THE AREA TO PICK UP ANOTHER 4-6+ INCHES OF SNOW WITH LOCALLY UP TO OVER 12 INCHES POSSIBLE WITH WINDS OF 20 TO 35+ MPH AND POSSIBLY HIGHER. THE CONSISTENCY OF FORCING OF UPPER JET STRUCTURE TOOLS ALL SUGGEST IF THIS TREND CONTINUES THE NEXT 24 HOURS THAT OUR AREA WILL SEE A MAJOR...HIGHER END WINTER STORM EVENT WITH POSSIBLE NEAR BLIZZARD CONDITIONS. WILL UPDATE THE LOCAL HWODVN HAZARDOUS WEATHER OUTLOOK PRODUCT FOR STRONGER AND HIGHER IMPACT WORDING. SATURDAY NIGHT AND SUNDAY...VERY MINOR CHANGES WITH LESS CLOUDS ARE LIKELY SUPPORTING LOWER MINS FROM OUR SNOW-PACK AND HIGHER MAX TEMP VALUES FROM LATE FEBRUARY SUNSHINE. LATER SHIFTS MAY NEED TO BUMP HIGHS A FEW MORE DEGREES DUE TO THE SUNSHINE. SUNDAY NIGHT...SEE INCREASING CLOUDS AND KEPT VERY LOW POPS FAR WEST SECTIONS OVERNIGHT AS LEADING EDGE OF ELEVATED FORCING FOR THE NEXT MAJOR WINTER STORM ARRIVES WITH MAIN BRUNT OF FORCING ON TAP TO IMPACT THE AREA LATER ON MONDAY PM HOURS INTO TUESDAY. MONDAY THROUGH NEXT WEDNESDAY...HAVE UPPED POPS MONDAY NIGHT AND TUESDAY TO LIKELY WITH MODERATE TO HEAVY SNOW AMOUNTS SUGGESTED. NUMEROUS TOOLS SUGGEST MOST OF THE AREA TO SEE WELL OVER 4+ INCHES WITH MOST RELIABLE TOOLS ALL SUGGESTING A SWATH OF 6-12+ INCHES OF HEAVY SNOW THAT RIGHT NOW IS TRENDING TOWARD A IRK-MUS-FEP LINE. THIS SHOULD BE BETTER CLARIFIED IN THE NEXT 24 HOURS. IF PHASING ON THE BACK SIDE OCCURS AS SUGGESTED BY SOME SOLUTIONS WITH STRONGER OCCLUSION THEN STRONGER COLD CONVEYOR BELT SUGGESTED AND NEAR BLIZZARD CONDITIONS LIKELY. SOME TOOLS SUGGEST WIND GUSTS OF 40-45 MPH WHICH ARE VERY CLOSE TO BLIZZARD THRESHOLD FOR LATER SHIFTS TO MONITOR. THERE IS NO DOUBT THIS WILL BE A MAJOR EVENT LAST 12-18+ HOURS AND LIKELY GREATER THAN THE EVENT THE PAST 24 HOURS. THIS IS A DEVELOPING SYSTEM THAT WILL STRENGTHEN VERSUS A WEAKENING AND FILLING SYSTEM THAT PASSED. ADD WERE IN THE NATURAL BAROCLINIC ZONE OF A PRONOUNCED SNOW AND NO SNOW LINE...THIS MAKES RISK OF A MAJOR EVENT GREATER. THE DATA AS OF NOW...SUPPORTS AT LEAST PART OF THE AREA WILL SEE A MAJOR WINTER STORM. AREA SNOW TO LIQUID WATER EQUIVALENT RATIOS ARE SUGGESTED TO BE IN THE 12-15 TO 1 RANGE. ARE TEMPERATURES SHOULD STAY IN THE MID 20S TO LOWER 30S FOR THIS EVENT. THURSDAY AND FRIDAY...DRY WITH BELOW NORMAL TEMPERATURES AND WITH AN EVEN GREATER THICKER AND FRESH SNOW PACK LIKELY...AREA TEMPS ARE AGAIN PROBABLY TOO MILD. MINS COULD BE AT LEAST 5 TO 10 DEGREES TOO MILD FOR LATER SHIFTS TO RECONSIDER. NORTHWESTERLY FLOW AND BELOW NORMAL TEMPERATURES REMAIN APPEAR LIKELY INTO THE FIRST FEW DAYS OF MARCH...ALL INDICATIONS ARE THIS MARCH WILL NOTHING LIKE THE RECORD WARM MARCH OF 2012. NICHOLS && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1127 PM CST FRI FEB 22 2013 CYCLONIC FLOW AROUND LOW PRESSURE OVER NORTHERN LAKE MICHIGAN AND HIGH LOW LEVEL MOISTURE WILL KEEP CLOUDS BASED 2KT AND 4KFT IN PLACE EARLY SATURDAY MORNING. SKIES SHOULD CLEAR FROM WEST TO EAST BEGINNING AROUND SUNRISE WITH THE CLEAR LINE REACHING THE MISSISSIPPI RIVER BY NOON. VISIBILITIES WERE REMAIN AOA 6SM WITH WEST TO SOUTHWEST WINDS AROUND 10 KNOTS. DLF && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...LE SHORT TERM...LE LONG TERM...WDN AVIATION...DLF
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
1050 PM MST FRI FEB 22 2013 .AVIATION... 06Z TAF CYCLE UPPER DISTURBANCE PASSING OVER NORTH CENTRAL/NORTHEAST NEW MEXICO BEFORE 12Z AND WILL BE ACCOMPANIED BY A COLD FRONT. SHSN ALREADY WANING WEST OF THE CENTRAL MT CHAIN...WHILE SCT MAINLY MVFR CIGS/VBSYS IN SHSN/BR WILL OCCASIONALLY OBSCURE MTS OVER THE NORTHEAST THIRD OR SO OF THE STATE UNTIL AROUND 09Z THEN SHOULD TAPER OFF AS THE DISTURBANCE TRACKS INTO THE TX PANHANDLE. WINDS ALOFT BECOMING WLY AND SFC LEE TROUGH DEVELOPING AFT 23/18Z. && .PREV DISCUSSION...324 PM MST FRI FEB 22 2013... ANOTHER WEAK UPPER WAVE SLIDING ACROSS NORTHERN NM IN FAST NNW FLOW WILL KEEP THE SNOW MACHINE GOING OVER THE HIGH TERRAIN THROUGH EARLY SATURDAY. LOCAL HI RES WRF...NAM12...AND HRRR SOLUTIONS SHOW MESOSCALE FEATURES WITHIN THE LARGER SCALE REGIME SLIDING SOUTHWARD OUT OF THE NORTHERN MTS TONIGHT INTO THE RIO GRANDE VALLEY FROM SANTA FE TO THE ABQ METRO AREA THIS EVENING. INCREASED POPS ACCORDINGLY AND PLACED A DUSTING TO 1 INCH FOR THESE AREAS. FOR THE HIGH TERRAIN THERE HAS BEEN AN EBB AND FLOW OF LIGHT TO MODERATE SNOW AND SNOW SHOWERS SINCE THURSDAY MORNING WITH 1-4 INCHES OF SNOW EACH 12HR PERIOD ADDING UP TO SOME MODEST ACCUMULATIONS. TONIGHT WILL FEATURE ANOTHER 1-4 INCHES ABOVE 7500 FEET. A DISTINCT BREAK WILL TAKE SHAPE FOR THE ENTIRE AREA SATURDAY BEHIND TONIGHTS UPPER WAVE. A HIGHER IMPACT STORM WILL MOVE OVER NORTHERN NM SATURDAY NIGHT AND SUNDAY. THIS SYSTEM WILL BRING WITH IT A STRONG PACIFIC COLD FRONT AND ANOTHER ROUND OF WIND AND SNOW. THE NORTHERN MTS WILL SEE AN ADDITIONAL SEVERAL INCHES OF SNOW BUT WITH MORE WIND AND COLDER TEMPS THAN THE PAST 36 HRS SO SOME WINTER HIGHLIGHTS ARE EXPECTED. THE NE PLAINS WILL BE IN THE ACTION AS WELL WITH A TROWAL FEATURE SLIDING OVER THE AREA AS THE STORM SYSTEM DEEPENS OVER THE PLAINS STATES. TEMPS WILL DIVE BACK 10 TO 20F BLW NORMAL ONCE AGAIN. CONFIDENCE IS NOT HIGH ENOUGH FOR A WINTER STORM WATCH AT THIS TIME BUT IF MODEL TRENDS CONTINUE TO STRENGTHEN THAT COULD CHANGE. COLD TEMPS WILL CONTINUE INTO MONDAY AND TUESDAY WITH BREEZY TO LOCALLY WINDY CONDITIONS EXPECTED. BY LATE TUESDAY GUIDANCE SHOWS ANOTHER WAVE SLIDING SE OVER THE AREA WITH MORE SNOWFALL ACCUMS FOR THE NORTHERN HIGH TERRAIN. ANOTHER BREAK IS ON TAP WEDNESDAY BEFORE ANOTHER FAST MOVING SHEARED WAVE SLIDES OVER THURSDAY. BY THE END OF THE WEEK GUIDANCE FINALLY STOPS THE WAVE TRAIN AND SLOWLY PUSHES A RIDGE TOWARD THE AREA WITH SLIGHTLY WARMER TEMPS. GUYER && .FIRE WEATHER... AN UPPER LEVEL TROUGH WILL MOVE RAPIDLY TO THE EAST ACROSS NORTHERN NM TONIGHT PRODUCING LIGHT TO MODERATE SNOWFALL IN THE HIGHER TERRAIN AND ISOLATED AREAS OF LIGHT SNOW IN THE LOWER ELEVATIONS. MOIST NORTHWEST TO WEST FLOW ACROSS NORTHERN AND CENTRAL NM TONIGHT WILL KEEP RELATIVE HUMIDITIES ABOVE NORMAL THROUGH SATURDAY MORNING. INCREASING 700 MB WINDS AND THE FORMATION OF WEAK SURFACE LOW PRESSURE IN EASTERN NM ON SATURDAY WILL RESULT IN WEST WIND GUSTS UP TO 35 MPH EAST OF THE CENTRAL MOUNTAINS ALONG AND SOUTH OF I-40. MINIMUM RELATIVE HUMIDITY IN THESE AREAS WILL GENERALLY BE IN THE 17-25 PERCENT RANGE...SO THE RISK OF CRITICAL FIRE WEATHER CONDITIONS DEVELOPING SATURDAY AFTERNOON APPEARS LOW. VENTILATION SATURDAY WILL BE FAIR TO GOOD WEST OF THE CONTINENTAL DIVIDE AND GOOD TO VERY GOOD EAST OF THE DIVIDE. A SIGNIFICANTLY STRONGER AND COLDER UPPER LEVEL LOW WILL MOVE FROM THE EASTERN GREAT BASIN ACROSS NORTHERN AND CENTRAL NM SATURDAY NIGHT THROUGH SUNDAY AND THEN EXIT ACROSS NORTHEASTERN NM SUNDAY NIGHT. THE TRACK OF THIS SYSTEM HAS BEEN PROGRESSIVELY FURTHER TO THE SOUTH ON MODEL RUNS OVER THE PAST 48 HOURS. THIS TRACK WILL GENERATE THE STRONGEST WINDS ACROSS SOUTHERN NM ON SUNDAY. THE DRIEST LOW LEVEL AIR AND STRONGEST WINDS WILL LIKELY STAY TO THE SOUTH OF THE FIRE DISTRICT. WINDS WILL STILL BE MODERATE SUNDAY WITH GUSTS BETWEEN 30 TO 35 MPH ACROSS CENTRAL NM...ESPECIALLY SOUTH OF I-40. MOISTURE ACCOMPANYING THIS UPPER LEVEL TROUGH WILL KEEP DAYTIME RELATIVE HUMIDITY VALUES NEAR OR ABOVE 20 PERCENT...SO CRITICAL FIRE WEATHER CONDITIONS WILL BE UNLIKELY. SUSTAINED NORTHWEST WINDS SUNDAY WILL RANGE FROM 10 TO 25 MPH....RESULTING IN VERY GOOD TO EXCELLENT VENTILATION. AS THE UPPER LOW MOVES EASTWARD ACROSS WESTERN OK SUNDAY NIGHT...WRAP-AROUND MOISTURE WILL KEEP RELATIVE HUMIDITY HIGH ACROSS EASTERN NM....WHILE DECREASING WIND SPEEDS AND RESIDUAL LOW LEVEL MOISTURE ACROSS CENTRAL AND WESTERN NM WILL ALLOW FOR STRONG RELATIVE HUMIDITY RECOVERIES SUNDAY NIGHT THROUGH MONDAY MORNING. HIGH PRESSURE WILL BUILD ACROSS NM FROM THE WEST ON MONDAY WITH LIGHTER WINDS AND DRIER LOW LEVEL AIR MOVING INTO THE REGION. AFTERNOON WINDS IN THE EASTERN PLAINS WILL CREATE FAIR TO GOOD VENTILATION...BUT LIGHTER WINDS ACROSS THE REMAINDER OF NM WILL CREATE ONLY POOR TO FAIR VENTILATION. ANOTHER UPPER LEVEL TROUGH MAY AFFECT NORTHERN AND CENTRAL NM ON TUESDAY...MOST LIKELY IN THE AFTERNOON TO EVENING HOURS...THOUGH MODEL GUIDANCE STILL VARIES ON TIMING. THIS SYSTEM WOULD MOST LIKELY BRING SNOW TO NORTHERN NM...BUT CENTRAL NM COULD RECEIVE SNOW GIVEN A SLIGHT ADJUSTMENT IN THE TRACK OF THE STORM. THIS TROUGH WILL MOST LIKELY KEEP TEMPERATURES BELOW NORMAL AND RELATIVE HUMIDITY ABOVE NORMAL THROUGH MIDWEEK. WEAK HIGH PRESSURE WILL DRIFT ACROSS NM WEDNESDAY WITH A GREATER POSSIBILITY FOR STRONGER MORNING INVERSIONS AND POORER DAYTIME VENTILATION. 28 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
421 AM EST SAT FEB 23 2013 .SYNOPSIS... OUR REGION IS WEDGED BETWEEN ONE LOW PRESSURE CENTER MOVING FROM THE NORTHERN GREAT LAKES INTO CANADA...AND ANOTHER ONE DEVELOPING WHILE HEADING OFFSHORE THE MIDATLANTIC COAST. WE CAN EXPECT CLOUDS WITH INCREASING CHANCES OF LIGHT RAIN AND SNOW TODAY INTO TONIGHT. SOME LOCATIONS MAY EVEN SEE PATCHY FREEZING DRIZZLE OR LIGHT FREEZING RAIN INTO TONIGHT. TEMPERATURES WILL NOT BE MOVING MUCH THE NEXT SEVERAL DAYS. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 1000 PM UPDATE...CUT BACK ON POPS FOR MOST OF THE AREA THROUGH DAYBREAK BASED ON OBS AND CURRENT TRENDS. THE RUC 500 VORTICITY FIELD SEEMS TO HAVE A GOOD HANDLE ON WHERE THE BEST SHOT FOR PRECIP WILL BE OVERNIGHT. RIGHT NOW WE HAVE A WEAK LOBE OF VORTICITY STRETCHING FROM THE FINGER LAKES SOUTH AND EAST INTO NEPA. THIS LOBE WILL MOVE NORTHEAST THROUGH 09Z THROUGH CNY AND OTSEGO/DELAWARE COUNTY. AS THIS HAPPENS THE WEAK RETURNS WE ARE SEEING NOW ON RADAR IN THE FORM OF VERY LIGHT SNOW OR FLURRIES WILL MOVE NORTHEAST AND EVENTUALLY OUT OF THE AREA BY 12Z. MEANWHILE A MORE IMPRESSIVE AREA OF DRIZZLE AND LIGHT PRECIP IN THE PHILLY AREA WILL BE CAREFULLY WATCHED. AT THIS POINT BASED ON RADAR AND MATCHING IT UP WITH THE UPPER LEVEL LIFT...THIS BATCH SHOULD MOVE NORTH AND EAST WHICH WOULD KEEP IS AWAY FROM OUR SE CWA. THIS IS CONFIRMED BY DESCENT IN THE COLUMN AT KAVP. IT APPEARS MORE ENERGY NOW OVER THE OHIO VALLEY WILL SWING THROUGH BETWEEN 12Z AND 15Z ESPECIALLY OVER THE WESTERN CWA AND THIS IS WHEN I WILL RAMP POPS BACK UP AGAIN. A QUICK GLANCE AT THE 0Z MODELS AND IT LOOKS LIKE FAIRLY LIGHT QPF THROUGH EARLY AFTERNOON...AND MAIN FOCUS OF INTEREST MAY BE THIS EVENING/TONIGHT FOR WINTER POTENTIAL. MORE WITH THE NEXT UPDATE... 945 PM UPDATE...ISOLATED TO SCATTERED SNOW SHOWERS CONTINUE OVER THE AREA AS SECONDARY ALTHOUGH WEAKER SHORT WAVE CROSSES THE CWA. AFTER THIS SHORT WAVE PASSES ACTIVITY MAY EVEN DIMINISH FURTHER FOR THE REMAINDER OF THE OVERNIGHT PERIOD. ONLY MINOR TEMP ADJUSTMENTS NEEDED. 640 PM UPDATE...LOCAL RADAR SHOWS SCATTERED LIGHT RETURNS ACROSS THE EASTERN CWA PRIMARILY EAST OF I81. AT THE AFC NOT MUCH IS BEING REPORTED WITH TEMP/DEW POINT SPREADS OF 10-15 DEGREES. AT SOME SITES FLURRIES OR VERY BRIEF SNOW SHOWERS HAVE OCCURRED. THIS ACTIVITY WAS INITIATED BY A MID LEVEL SHORT WAVE WITH ANOTHER ONE EXPECTED LATER THIS EVENING BUT ONLY SCATTERED ACTIVITY IS FORECAST WITH THIS SECOND FEATURE. WILL CONTINUE WITH JUST LOW CHIC POPS THROUGH THE OVERNIGHT PERIOD WITH PRECIP FALLING AS JUST SNOW THROUGH 06Z. AFTER 06Z MID LEVEL WARMING COMBINED WITH SHALLOW MOISTURE COULD PRODUCE SOME PATCHY FREEZING DRIZZLE ACROSS THE SOUTHERN TIER AND NE PA. CURRENT FORECAST IN GOOD SHAPE. 3 PM UPDATE... A NW TO SE BAND OF LIGHT PRECIP IS MOVG NE INTO THE AREA. IT IS DRYING AS IT MOVES IN. THE BEST CHC OF ANYTHING THIS AFTN WILL BE LIGHT SNOW IN THE FINGER LAKES. ACCUMS LESS THAN AN INCH. REST OF THE CWA LITTLE TO NOTHING. BETTER LIFT AND MOISTURE RETURNS LATE TONIGHT WITH LOW CLOUDS SO MAYBE SOME LIGHT PRECIP IN THE FORM OF FLURRIES OR MAYBE FREEZING DRIZZLE. TOTAL QPF ONLY A HUNDREDTH OR TWO AT BEST. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... 3 PM UPDATE... SATURDAY AND SATURDAY NIGHT BETTER DYNAMICS AND MOISTURE MOVES IN AHEAD AN INTENSIFYING COASTAL LOW MOVG NE TO LONG ISLAND SAT NGT AND A DEEP STACKED LOW OVER THE MI UP MOVG EAST. UNFORTUNATELY THE SW FLOW IS BRINGING IN WARM AIR. PRECIP MAY START AS SNOW THEN MIX OR CHANGE TO RAIN SAT. COLDER AIR COMES IN SAT NGT TO CHANGE MIXED PRECIP BACK TO SNOW. LOW LEVEL CAA WILL BRING SFC TEMPS BELOW FREEZING FIRST SO FREEZING RAIN IS POSSIBLE IN NE PA AND THE CATSKILLS SAT EVE. THE BEST CHC OF ACCUMULATING SNOW WILL BE THE HIGH TERRAIN OF THE CATSKILLS. MAYBE ADVISORY SNOW THERE. THE POCONOS MAY BE TOO WARM. SUNDAY AND SUNDAY NIGHT WE WILL BE UNDER THE UPPER LEVEL LOW AS IT MOVES SE BEHIND THE COASTAL SFC NOREASTER. COLD AIR ADVECTION AND A WEAK FLOW OFF THE GREAT LAKES WILL MEAN WIDESPREAD LIGHT SNOW SHWOERS SUNDAY TO SUNDAY NIGHT. THE QUESTION IS WHEN IT WILL END. FOR NOW HAVE IT ENDING SUN NGT BUT IT COULD CONTINUE INTO MONDAY. BY MONDAY NIGHT SFC HIGH PRESSURE IS OVER THE CWA WITH AN UPPER LEVEL RIDGE JUST UPSTREAM SO LOW CLOUDS AND SNOW SHOWERS WILL TAPER OFF SUN NGT TO MON. WITH THE NW FLOW AND LAKE ENHANCEMENT AND NEARNESS TO THE UPPER LEVEL LOW THE NRN COUNTIES COULD GET A FEW INCHES AGAIN. && .LONG TERM /MONDAY THROUGH FRIDAY/... 345 AM UPDATE... WELCOME TO CUTOFF COUNTRY. A PATTERN MORE REMINISCENT OF EARLY SPRING...THAT IS...AMPLIFIED WITH CUTOFF LOWS...WILL DOMINATE THE LONG TERM PERIOD OF THE FORECAST. DAYTIME TEMPERATURES THOUGH WILL NOT STRAY MUCH FROM CLIMATOLOGY. ECMWF AND GFS AGREE THAT AN UPPER LOW WILL BE SHIFTING ITS WAY UP THE OHIO VALLEY TUESDAY INTO TUESDAY NIGHT. THE DETAILS ARE A BIT DIFFERENT AS TO WHAT HAPPENS FROM THERE...BUT BOTH SHOW A VERSION OF A NORTHERN HIGH PLAINS UPPER TROUGH DIGGING INTO THE MIDWEST AND CAPTURING/CONSOLIDATING WITH THE ORIGINAL UPPER LOW. WHEN THAT OCCURS...IT WILL BE STUCK IN OUR VICINITY AND IN ABSOLUTELY NO RUSH TO GO ANYWHERE THROUGH FRIDAY. FOR US...THAT MEANS PLENTY OF CLOUD COVER...OCCASIONAL SNOW AND/OR RAIN SHOWERS...AND LITTLE MOVEMENT IN TEMPERATURES DIURNALLY. ON THE LEADING EDGE OF THIS PATTERN...MODEL CONSENSUS HAS SHIELD OF PRECIPITATION MOVING IN A BIT SLOWER THAN PREVIOUS FORECAST...MAINLY LATE TUESDAY INTO TUESDAY NIGHT. THIS SLOWER TREND IS NOT A SURPRISE GIVEN AMPLIFIED NATURE TO PATTERN. GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. PRESSURE GRADIENT BETWEEN LARGE DEPARTING NEW ENGLAND HIGH AND INCOMING LOW WILL BE QUITE STEEP...AND I THUS INCREASED WINDS FOR THE TUESDAY NIGHT/EARLY WEDNESDAY PERIOD. NOT SURE YET HOW MUCH OF THE STRONG WINDS ALOFT WILL BE ABLE TO MIX DOWN...THE BOUNDARY LAYER MAY BE FAIRLY STABLE. ONE NOTEWORTHY DIFFERENCE IN THE MODELS IS THAT THE GFS IS COLDER AT 925MB THAN AT 850MB /WHERE IT IS MAINLY ABOVE FREEZING/ AS THE PRECIPITATION MOVES IN TUESDAY. ECMWF MEANWHILE IS VICE- VERSA. SO THE GFS WOULD SUGGEST POSSIBLE FREEZING RAIN WHILE THE ECMWF IS MORE OF A SIMPLE RAIN/SNOW MIX. I HAVE NOT ADDED CHANCE OF FREEZING RAIN TO GRIDS JUST YET...BUT THIS POTENTIAL WILL HAVE TO BE ASSESSED AS THE EVENT GETS CLOSER. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... 06Z UPDATE... COMPLICATED AVIATION FORECAST DURING THIS TAF PERIOD...WITH REGION IN MOIST FEED BETWEEN DEVELOPING LOW AROUND THE MID ATLANTIC COAST...AND ANOTHER LOW IN THE NORTHERN GREAT LAKES. LOW END VFR TO MVFR CIGS...COURTESY OF SHALLOW MOISTURE WHICH WILL OCCASIONALLY YIELD PATCHY FREEZING DRIZZLE KAVP-KBGM-KELM LATER THIS MORNING...BRIEF IFR CIG ALSO NOT OUT OF THE QUESTION LATER THIS MORNING FOR KBGM /AFTER 12Z/. CIGS GENERALLY STAY IN MVFR CATEGORY WITH LIGHT RAIN OR DRIZZLE DURING THE DAY CAUSING MVFR VIS AS OCCLUDED FRONT PASSES OVERHEAD WITH CONTINUED SHALLOW MOISTURE. BEHIND OCCLUDED FRONT TONIGHT...SATURATED LAYER GETS SQUEEZED BELOW LOWERING INVERSION AND IFR CIGS MAY IMPACT MOST TERMINALS. FREEZING DRIZZLE MAY ALSO RE-ENTER THE PICTURE. .OUTLOOK... LATE SAT NGT...MVFR/IFR IN MIXED PCPN. SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS. MON...VFR. TUE...MVFR/IFR IN RAIN AND/OR SNOW. WED...MVFR IN LAKE ENHANCED SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...HEDEN/MDP NEAR TERM...HEDEN/RRM/TAC SHORT TERM...TAC LONG TERM...MDP AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
105 AM EST SAT FEB 23 2013 .SYNOPSIS... A WEAK STORM SYSTEM AND FRONTAL COMPLEX WILL BRING A LIGHT WINTRY MIX OF SNOW, RAIN, OR FREEZING DRIZZLE OVERNIGHT. STEADIER PRECIPITATION IS LIKELY FOR MUCH OF THE AREA SATURDAY AFTERNOON AND EVENING...ASSOCIATED WITH A DEVELOPING STORM OFF THE MID ATLANTIC COAST. ONCE AGAIN...WE WILL LIKELY SEE A MIXTURE OF RAIN AND SNOW...AND MAYBE FREEZING RAIN. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 1000 AM UPDATE...CUT BACK ON POPS FOR MOST OF THE AREA THROUGH DAYBREAK BASED ON OBS AND CURRENT TRENDS. THE RUC 500 VORTICITY FIELD SEEMS TO HAVE A GOOD HANDLE ON WHERE THE BEST SHOT FOR PRECIP WILL BE OVERNIGHT. RIGHT NOW WE HAVE A WEAK LOBE OF VORTICITY STRETCHING FROM THE FINGER LAKES SOUTH AND EAST INTO NEPA. THIS LOBE WILL MOVE NORTHEAST THROUGH 09Z THROUGH CNY AND OTSEGO/DELAWARE COUNTY. AS THIS HAPPENS THE WEAK RETURNS WE ARE SEEING NOW ON RADAR IN THE FORM OF VERY LIGHT SNOW OR FLURRIES WILL MOVE NORTHEAST AND EVENTUALLY OUT OF THE AREA BY 12Z. MEANWHILE A MORE IMPRESSIVE AREA OF DRIZZLE AND LIGHT PRECIP IN THE PHILLY AREA WILL BE CAREFULLY WATCHED. AT THIS POINT BASED ON RADAR AND MATCHING IT UP WITH THE UPPER LEVEL LIFT...THIS BATCH SHOULD MOVE NORTH AND EAST WHICH WOULD KEEP IS AWAY FROM OUR SE CWA. THIS IS CONFIRMED BY DESCENT IN THE COLUMN AT KAVP. IT APPEARS MORE ENERGY NOW OVER THE OHIO VALLEY WILL SWING THROUGH BETWEEN 12Z AND 15Z ESPECIALLY OVER THE WESTERN CWA AND THIS IS WHEN I WILL RAMP POPS BACK UP AGAIN. A QUICK GLANCE AT THE 0Z MODELS AND IT LOOKS LIKE FAIRLY LIGHT QPF THROUGH EARLY AFTERNOON...AND MAIN FOCUS OF INTEREST MAY BE THIS EVENING/TONIGHT FOR WINTER POTENTIAL. MORE WITH THE NEXT UPDATE... 945 PM UPDATE...ISOLATED TO SCATTERED SNOW SHOWERS CONTINUE OVER THE AREA AS SECONDARY ALTHOUGH WEAKER SHORT WAVE CROSSES THE CWA. AFTER THIS SHORT WAVE PASSES ACTIVITY MAY EVEN DIMINISH FURTHER FOR THE REMAINDER OF THE OVERNIGHT PERIOD. ONLY MINOR TEMP ADJUSTMENTS NEEDED. 640 PM UPDATE...LOCAL RADAR SHOWS SCATTERED LIGHT RETURNS ACROSS THE EASTERN CWA PRIMARILY EAST OF I81. AT THE AFC NOT MUCH IS BEING REPORTED WITH TEMP/DEW POINT SPREADS OF 10-15 DEGREES. AT SOME SITES FLURRIES OR VERY BRIEF SNOW SHOWERS HAVE OCCURRED. THIS ACTIVITY WAS INITIATED BY A MID LEVEL SHORT WAVE WITH ANOTHER ONE EXPECTED LATER THIS EVENING BUT ONLY SCATTERED ACTIVITY IS FORECAST WITH THIS SECOND FEATURE. WILL CONTINUE WITH JUST LOW CHIC POPS THROUGH THE OVERNIGHT PERIOD WITH PRECIP FALLING AS JUST SNOW THROUGH 06Z. AFTER 06Z MID LEVEL WARMING COMBINED WITH SHALLOW MOISTURE COULD PRODUCE SOME PATCHY FREEZING DRIZZLE ACROSS THE SOUTHERN TIER AND NE PA. CURRENT FORECAST IN GOOD SHAPE. 3 PM UPDATE... A NW TO SE BAND OF LIGHT PRECIP IS MOVG NE INTO THE AREA. IT IS DRYING AS IT MOVES IN. THE BEST CHC OF ANYTHING THIS AFTN WILL BE LIGHT SNOW IN THE FINGER LAKES. ACCUMS LESS THAN AN INCH. REST OF THE CWA LITTLE TO NOTHING. BETTER LIFT AND MOISTURE RETURNS LATE TONIGHT WITH LOW CLOUDS SO MAYBE SOME LIGHT PRECIP IN THE FORM OF FLURRIES OR MAYBE FREEZING DRIZZLE. TOTAL QPF ONLY A HUNDREDTH OR TWO AT BEST. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... 3 PM UPDATE... SATURDAY AND SATURDAY NIGHT BETTER DYNAMICS AND MOISTURE MOVES IN AHEAD AN INTENSIFYING COASTAL LOW MOVG NE TO LONG ISLAND SAT NGT AND A DEEP STACKED LOW OVER THE MI UP MOVG EAST. UNFORTUNATELY THE SW FLOW IS BRINGING IN WARM AIR. PRECIP MAY START AS SNOW THEN MIX OR CHANGE TO RAIN SAT. COLDER AIR COMES IN SAT NGT TO CHANGE MIXED PRECIP BACK TO SNOW. LOW LEVEL CAA WILL BRING SFC TEMPS BELOW FREEZING FIRST SO FREEZING RAIN IS POSSIBLE IN NE PA AND THE CATSKILLS SAT EVE. THE BEST CHC OF ACCUMULATING SNOW WILL BE THE HIGH TERRAIN OF THE CATSKILLS. MAYBE ADVISORY SNOW THERE. THE POCONOS MAY BE TOO WARM. SUNDAY AND SUNDAY NIGHT WE WILL BE UNDER THE UPPER LEVEL LOW AS IT MOVES SE BEHIND THE COASTAL SFC NOREASTER. COLD AIR ADVECTION AND A WEAK FLOW OFF THE GREAT LAKES WILL MEAN WIDESPREAD LIGHT SNOW SHWOERS SUNDAY TO SUNDAY NIGHT. THE QUESTION IS WHEN IT WILL END. FOR NOW HAVE IT ENDING SUN NGT BUT IT COULD CONTINUE INTO MONDAY. BY MONDAY NIGHT SFC HIGH PRESSURE IS OVER THE CWA WITH AN UPPER LEVEL RIDGE JUST UPSTREAM SO LOW CLOUDS AND SNOW SHOWERS WILL TAPER OFF SUN NGT TO MON. WITH THE NW FLOW AND LAKE ENHANCEMENT AND NEARNESS TO THE UPPER LEVEL LOW THE NRN COUNTIES COULD GET A FEW INCHES AGAIN. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 140 PM UPDATE... LONG TERM STARTS OFF WITH AN ACTIVE PATTERN. UL SYSTEM CURRENTLY SLAMMING INTO THE PACIFIC NORTHWEST WL DIVE SOUTH AND CLOSE OFF ACRS THE CNTRL PLAINS BY EARLY NEXT WEEK. AS IT CROSSES THE ROCKIES IT WL UNDERGO LEE-SIDE CYCLOGENESIS AND INDUCE SFC LOW DVLPMNT ON MONDAY WHICH WL TRANSLATE UP TWD CWA BY MID-WEEK. HOW QUICKLY IT IS ABLE TO SPREAD PCPN UP INTO FA RMNS THE QUESTION WITH MED RANGE MODELS HOLDING ONTO DRY AIR WITH H5 RIDGE THRU 12Z TUESDAY. THUS HV DELAYED INTRODUCING ANY POPS INTO NRN SXNS THRU THIS TIME WITH ONLY CHC EXPECTED FM SRN TIER AND POINTS SOUTH MAINLY IN THE FORM OF LGT SNOW. PCPN OVRSPRDS AREA BY TUE THO HOW QUICKLY IT DOES SO RMNS UP IN THE AIR AT THIS POINT. 00Z EURO IS MUCH SLOWER WITH PROGRESS AND KEEPS IT OUT OF CWA THRU 18Z TUE AND THEN ONLY BRINGS IT INTO WRN AND SRN HALF BY 00Z WED. 12Z GFS IS ABOUT 6 HRS QUICKER. THUS THINK THAT LKLY POPS WL BE THE WAY TO GO FOR THE ENTIRE PD ON TUESDAY WITH HIGHER LKLYS ACRS THE SOUTH AND 55 POPS CONFINED TO NRN AND ERN ZONES FOR CONTINUITY`S SAKE AND IN AGREEMENT WITH SURROUNDING OFFICES. STILL PLENTY OF TIME TO WORK OUT THE DETAILS LATER. AS FOR PTYPE, GFS CONTS TO BRING IN WRMR H8 TEMPS AS IT HAS DONE ALL WINTER LONG AND EURO KEEPS H8 TEMPS BLO 0C. THUS HV CONTD WITH A RAIN/SNOW MIX WRDNG FOR TUESDAY. H5 LOW RIDES WEST OF CWA UP THE GREAT LKS TUE NGT INTO WED AND TRIES TO TRANSFER ENERGY OFF THE COAST WITH SFC LOW RIDING UP FM THE SERN U.S., BUT MAIN UL LOW DEEPENS TO OUR WEST AS ENERGY IS PROGGED TO DIVE INTO THE BASE OF THE TROF ON WED FM THE SRN PLAINS. AS OF NOW ENERGY TRANSFER DOES NOT APPEAR TO HAPPEN BUT THAT CUD ALWAYS CHG. CHC POPS WL CONT THRU RMNDR OF THE WEEK AS UL LOW CLOSES OFF EAST OF THE MS VLY. TEMPS WL BE FAIRLY STEADY WITH HIGHS IN THE MID-30S UNDER EXTENSIVE CLD CVR. OVRNGT LOWS WL DROP THRU THE END OF THE WEEK INTO THE 20S AS NRLY FLOW BRINGS IN CLD AIR. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... 06Z UPDATE... COMPLICATED AVIATION FORECAST DURING THIS TAF PERIOD...WITH REGION IN MOIST FEED BETWEEN DEVELOPING LOW AROUND THE MID ATLANTIC COAST...AND ANOTHER LOW IN THE NORTHERN GREAT LAKES. LOW END VFR TO MVFR CIGS...COURTESY OF SHALLOW MOISTURE WHICH WILL OCCASIONALLY YIELD PATCHY FREEZING DRIZZLE KAVP-KBGM-KELM LATER THIS MORNING...BRIEF IFR CIG ALSO NOT OUT OF THE QUESTION LATER THIS MORNING FOR KBGM /AFTER 12Z/. CIGS GENERALLY STAY IN MVFR CATEGORY WITH LIGHT RAIN OR DRIZZLE DURING THE DAY CAUSING MVFR VIS AS OCCLUDED FRONT PASSES OVERHEAD WITH CONTINUED SHALLOW MOISTURE. BEHIND OCCLUDED FRONT TONIGHT...SATURATED LAYER GETS SQUEEZED BELOW LOWERING INVERSION AND IFR CIGS MAY IMPACT MOST TERMINALS. FREEZING DRIZZLE MAY ALSO RE-ENTER THE PICTURE. .OUTLOOK... LATE SAT NGT...MVFR/IFR IN MIXED PCPN. SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS. MON...VFR. TUE...MVFR/IFR IN RAIN AND/OR SNOW. WED...MVFR IN LAKE ENHANCED SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...RRM/TAC NEAR TERM...HEDEN/RRM/TAC SHORT TERM...TAC LONG TERM...PVN AVIATION...MDP
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
330 AM EST SAT FEB 23 2013 .SYNOPSIS... A STORM SYSTEM WILL BRING MODERATE RAIN TODAY FOLLOWED BY DRY HIGH PRESSURE BUILDING IN ON SUNDAY. MOISTURE INCREASES AGAIN ON MONDAY WITH SOME RAIN EXPECTED MONDAY NIGHT INTO TUESDAY AS ANOTHER SYSTEM MOVES UP THE COAST. SLIGHTLY COOL WEATHER WILL FOLLOW FOR THE LATTER PART OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 3 AM SATURDAY...A WIDESPREAD SIGNIFICANT RAINFALL EVENT IS UNFOLDING ACROSS THE FORECAST AREA AS A SERIES OF WEAK WAVES OF LOW PRESSURE MOVE UP THE COAST ALONG A FRONT. THE RISK FOR WET WEATHER WILL COME TO AN END TONIGHT...VERY LATE AT THE COAST. PRECIPITABLE WATER VALUES WILL PEAK BETWEEN 1.5 AND 1.75 INCHES THIS MORNING...THROUGH MIDDAY. TOTAL RAINFALL AMOUNTS WITH THIS EVENT WILL REACH 1 TO 2 INCHES WITH SOME AREAS RECEIVING AS MUCH AS 3 INCHES. THE CHARACTER OF THE PRECIPITATION WILL MAINLY BE STRATIFORM RAIN. HOWEVER...THE FRONT...JUST OFFSHORE MAY MEANDER ONTO THE COAST AHEAD OF THE NEXT WAVE OF LOW PRESSURE MOVING UP THE SOUTHEAST COAST THIS MORNING. THEREFORE...WILL INCLUDE CONVECTIVE SHOWERS AND AN ISOLATED THUNDERSTORM. THE THUNDERSTORMS WILL BE ELEVATED AS THE AIRMASS WILL REMAIN STABLE NEAR THE SURFACE. A MID-LEVEL TROUGH WILL FINALLY KICK THE FRONT FAR ENOUGH E SO THAT THE RISK FOR RAIN WILL COME TO AN END DURING THE OVERNIGHT HOURS. HIGH PRESSURE CENTERED ACROSS NEW ENGLAND WILL WEDGE UPSTREAM OF THE FRONTAL SYSTEM...ACTING NOT ONLY TO STABILIZE THE LOW-LEVELS...BUT TO REINFORCE THE COOL AIR IN THE LOW-LEVELS. SO WHILE WARMER AND MUCH MORE MOIST AIR STREAMS IN ON INCREASING WSW WINDS ALOFT...BELOW ABOUT 3-4 KFT IT WILL BE COOL AND STABLE. RAIN FALLING INTO THIS ENVIRONMENT WILL KEEP THE INVERSION LOCKED IN. THIS WILL ENSURE A CLOUDY DAY. THE FURTHER INLAND YOU TRAVEL...THE LOWER AND STRONGER WILL BE THIS INVERSION. THUS...HIGHS ACROSS INLAND AREAS WILL ONLY REACH THE UPPER 40S TO LOWER 50S...COOLEST ALONG AND W OF INTERSTATE 95. ON THE COAST...IN CLOSEST PROXIMITY TO THE MEANDERING FRONT... TEMPS WILL BE MORE OF A CHALLENGE. AT THIS TIME...EXPECT 60 DEG TO BE IN REACH ACROSS MOST COASTAL LOCATIONS...HIGHEST DOWN AROUND GEORGETOWN AND UP ACROSS THE CAPE FEAR REGION. FOG WILL LIKELY PLAGUE MOST AREAS TODAY GIVEN THE STABLE LOW LAYERS AND NEAR SATURATED ENVIRONMENT. DO NOT EXPECT DENSE FOG...JUST LOW VISIBILITIES...AROUND A MILE AT TIMES IN RAIN AND FOG. ALONG THE COAST...SEA FOG MAY BLEED ONTO THE COAST...ESPECIALLY THIS MORNING AHEAD OF THE NEXT WAVE OF LOW PRESSURE. TONIGHT...DRIER AIR WILL BE SLOW TO BUILD INTO THE EASTERN CAROLINAS. NEARLY SATURATED GROUND AND LIGHT WINDS AT THE SURFACE SHOULD ALLOW WIDESPREAD STRATUS TO PERSIST FOR MUCH OF THE NIGHT. IN ADDITION... DO EXPECT FOG TO ENVELOP THE AREA AND THERE COULD BE AREAS OF DENSE FOG...ESPECIALLY LATE AT NIGHT. WE WILL CONTINUE TO MONITOR THE PROSPECTS FOR DENSE FOG TONIGHT. DIURNAL RANGE WILL BE ESPECIALLY SMALL INLAND WITH LOWS TONIGHT MAINLY IN THE LOWER TO MID 40S. AT THE COAST...UPPER 40S TO AROUND 50 DEG WILL BE MORE COMMON. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...ZONAL FLOW AND A DRY COLUMN WITH ONLY VERY PALTRY COLD AIR ADVECTION ON SUNDAY TO BRING PLENTY OF SUNSHINE AND FAIRLY SEASONABLE TEMPERATURES. SURFACE HIGH WILL BE BUILDING INTO THE OHIO VALLEY AND EVENTUALLY PA WHILE DIVING UPPER SYSTEM SPINS UP A LOW OVER NRN TX. AS BOTH TRANSLATE EASTWARD SUNDAY NIGHT A LONG WEST-EAST FRONT WILL DEVELOP ACRS THE LOWER MS VALLEY AND GULF STATES. WARM ADVECTION RAIN SHOULD BREAK OUT ACROSS THE SOUTHEAST ALBEIT IN FAIRLY LIGHT AMOUNTS INITIALLY. RAINFALL CHANCES AND INTENSITY SHOULD INCREASE LATE MONDAY INTO MONDAY NIGHT AS WEAK TRIPLE POINT LOW DEVELOPS AND APPROACHES. THE UPPER WAVE DRIVING THIS SYSTEM IS STRONGER AND FURTHER SOUTH THAN THE SYSTEM RELATED TO THE NEAR TERM..WHICH HAS LARGELY FAILED TO BE THE PROLIFIC RAIN PRODUCER THAT MODELS HAD ADVERTISED FOR DAYS. THE POSITION OF THIS FORTHCOMING UPPER LOW MAY BETTER SUPPORT A RAINY SCENARIO. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 3 AM SATURDAY...VERY HIGH RAINFALL CHANCES TO START THE PERIOD AND AN APPRECIABLE QPF EVENT MAY BE IN THE PROCESS OF WINDING DOWN. DEEP CUTOFF LOW OVER WRN TN WITH A WEAK TRIPLE POINT LOW SLIDING NNE UP THE CAROLINA COASTLINE. TEMPS WITH THIS ONE A TOUGH CALL AS NW TO SE GRADIENT IN HIGHS TUESDAY MAY BE CONSIDERABLE. STRONG LOW LEVEL JETTING AND SOME MID LEVEL HEIGHT FALLS TO SERVE AS DEEP LIFT BUT BY LATE MORNING THE SYSTEM SWINGS THROUGH LEADING TO STRONG DRY AIR ADVECTION. WEDNESDAY APPEARS TO BE A TRANSITIONAL DAY WITH A LITTLE WRAP AROUND MOISTURE ASSOCIATED WITH STRONG TRAILING ENERGY KICKING OUT THE TN CUTOFF BUT ALSO LEADING TO DEEP LONGWAVE TROUGHINESS IN THE EAST. AS THIS FEATURE BECOMES INCREASINGLY SLOW TO PROGRESS EAST FOR THE REST OF THE PERIOD PROLONGED COLD AIR ADVECTION WILL KEEP TEMPS BELOW CLIMO BY ABOUT A CATEGORY. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...EXPECT WIDESPREAD IFR/LIFR ACROSS THE TERMINALS THROUGH SATURDAY DUE TO LOWERED CIGS AND REDUCED VISIBILITIES IN RAIN AND FOG. LOWERED CIGS WITH AREAS OF RA AND REDUCED VISIBILITIES DUE TO FOG CONTINUE TO BE WIDESPREAD ACROSS THE AREA...WITH NORTHEAST WINDS AOB 6 KTS. EXPECT MAINLY LIFR CONDITIONS TO CONTINUE OVERNIGHT AND MODELS ARE IN GOOD AGREEMENT. RAIN WILL INCREASE THROUGH THE MORNING HOURS...WHICH WILL ALSO CONTRIBUTE TO REDUCED VISIBILITIES. THOUGH RAIN WILL TAPER OFF INTO SATURDAY EVENING...GIVEN CURRENT FCST SOUNDINGS AND TIME-HEIGHT ANALYSIS...PROJECT IFR CONDITIONS DUE TO LOWERED CIGS AND FOG TO PERSIST THROUGH THE TAIL END OF THE FORECAST PERIOD. NE WIND MAY BRIEFLY BECOME SSW ALONG THE COAST THIS MORNING AS OFFSHORE FRONT NEARS...BUT EXPECT NNE WINDS TO HOLD ACROSS KFLO AND KLBT. WINDS WILL BECOME WSW THROUGHOUT BY EVENING. EXTENDED OUTLOOK...EXPECT MVFR/IFR CONDITIONS OVERNIGHT SATURDAY... BECOMING VFR SUNDAY. RAIN REDEVELOPING MONDAY ENDING TUESDAY MORNING. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM FRIDAY...POSITIONING OF THE COASTAL FRONT WILL BE THE MAIN FOCUS AND PROBLEM OVERNIGHT INTO SATURDAY. BORDERLINE SCA THRESHOLDS WARRANT THE CONTINUATION OF THE SCA INTO SATURDAY. COASTAL FRONT REMAINS JUST OFFSHORE...JUST BEYOND THE OUTER WATERS OF THE ILM COASTAL WATERS. LATEST WINDS AND SEAS AT 41013 AND 41037 BUOYS ARE SE 15 TO 20 KT WITH 5 FT SEAS. LATEST WINDS AND SEAS AT 41110...41038 AND 41024 BUOYS ARE NE TO ENE 10 TO 20 KT WITH SEAS 3 TO 5 FT. SCA CONDITIONS SHOULD BE REALIZED OVERNITE AS THE SFC PG FURTHER TIGHTENS...AND THE COASTAL FRONT GETS PULLED CLOSER TO THE IMMEDIATE COAST IN ADVANCE OF THE LOW APPROACHING FROM THE SW. THE LATEST HRRR SFC WIND FIELDS KEEP THE COASTAL FRONT OVER THE WATERS RATHER THAN BRINGING IT ONSHORE. HAVE GEARED TOWARD THIS SCENARIO...AND HAVE NOW INDICATED THE COASTAL FRONT TO PARTIALLY MOVE ACROSS THE COASTAL WATERS OVERNITE INTO SAT. AS A RESULT... HAVE AD-LIBBED THE CURRENT CWF TEXT TO INDICATE THE DIFFERENCES IN BOTH WINDS AND SEAS IN THE NEAR SHORE...0-10 NM OUT...AND THE OUTER WATERS...10-20 NM OUT. HAVE ALSO INDICATED ISOLATED CONVECTION AFTER MIDNIGHT INTO THE DAYLIGHT HRS OF SAT DUE TO DYNAMICS FROM IMPULSES ALOFT INTERACTING WITH THE COASTAL FRONT. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...EARLY SUNDAY BRINGS A NORTHWEST WIND AS COLD FRONT MOVES FURTHER OFFSHORE AND LOW PRESSURE SLIDES UP OFF OF NEW ENGLAND COAST. A LITTLE BACKSWELL FROM THIS SYSTEM COMBINED WITH THE WIND WAVE WILL GENERATE ABOUT A 2 TO 4 FT PREDOMINANT SEA STATE. LATER SUNDAY HIGH PRESSURE PROGRESSES EASTWARD CUTTING WELL NORTH OF THE REGION LOCALLY VEERING THE WINDS. FLOW WILL MORE OR LESS STAY NORTHEASTERLY OR EASTERLY THROUGH MONDAY AS THE HIGH SLOWS AND A STORM SYSTEM DEEPENS ACROSS THE LOWER MS VALLEY WHILE APPROACHING. CONDITIONS THEN DETERIORATE MONDAY NIGH AS THE WARM FRONT APPROACHES BOTH VEERING AND INCREASING THE FLOW TO WHERE AND ADVISORY WILL LIKELY BE CALLED FOR. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 3 AM SATURDAY...VERY UNSETTLED TO START THE PERIOD AS A TRIPLE POINT LOW PRESSURE SLIDES UP THE COASTAL PLAIN. LOCAL ENHANCEMENT OF THE SOUTHERLY WINDS WILL PUSH WIND AND SEAS MORE SOLIDLY INTO SMALL CRAFT REALM COMPARED TO THE END OF THE SHORT TERM PERIOD BUT THE MILD AIR FLOWING OVER THE COOLER SSTS SHOULD PROBABLY PRECLUDE SUFFICIENT VERTICAL MIXING TO SUPPORT SUSTAINED GALE FORCE WINDS. JUST THE SAME GUSTINESS MAY NOT BE A BIG FACTOR BUT THERE IS SOME UNCERTAINTY AND FUTURE FORECASTS WILL HAVE TO ADDRESS THIS ISSUE. COLD FRONT SWEEPS ACROSS LATER IN THE DAY BEHIND THIS SYSTEM SHARPLY VEERING THE FLOW WHILE ALSO HERALDING A DECREASING TREND IN WIND AND SEAS ALBEIT POSSIBLY A SLOW ONE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR AMZ254-256. SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR AMZ250- 252. && $$ SYNOPSIS...MBB NEAR TERM...RJD SHORT TERM...MBB LONG TERM...MBB AVIATION...RJD/SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1234 AM EST SAT FEB 23 2013 .SYNOPSIS... RAIN WILL PERSIST INTO SATURDAY NIGHT. HIGH PRESSURE WILL BRING DRY AIR ON SUNDAY LASTING INTO EARLY MONDAY. ANOTHER ROUND OF RAINFALL WILL OCCUR MONDAY INTO TUESDAY. THE MIDDLE TO THE END OF NEXT WEEK WILL FEATURE DRY AND COOL CONDITIONS. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 1045 PM FRIDAY...CONTINUED LACK OF RADAR ECHOES ACROSS THE FA AT THE MOMENT. THE RADAR RETURNS FOR THE MOST PART OVER LAND WERE NOT REACHING THE GROUND VIA SFC OBSERVATIONS. THINKING REMAINS THAT THE FA WILL FILL IN WITH LIGHT TO MODERATE STRATIFORM TYPE RAINS AFTER MIDNIGHT...MAINLY TOWARD DAYBREAK SAT. AS A RESULT...OVERNITE AND DAYLIGHT SAT POPS HAVE BEEN ADJUSTED. LATEST PROGS KEEP THE COASTAL FRONT ALONG THE IMMEDIATE COAST...WITH VERY LITTLE INLAND MOVEMENT. IN FACT...LATEST HRRR PROGGED SFC WIND FIELD KEEPS A NORTHERLY COMPONENT IN THE WINDS ACROSS THE CWA OVERNITE INTO SAT. TONIGHTS MINS...NOT THE 24 HR MIN...WILL LIKELY OCCUR AROUND OR JUST AFTER MIDNIGHT...FOLLOWED BY A STEADY OR EVEN A SLOW/SLIGHT RISE IN TEMPS DURING THE PRE- DAWN HRS ESPECIALLY ALONG THE IMMEDIATE COAST. WEAK IMPULSES WITHIN SW-WSW FLOW ALOFT MAY PROVIDE ENOUGH DYNAMICS TO AID THE DEVELOPMENT OF ISOLATED CONVECTION ALONG THE COASTAL FRONT. HAVE INDICATED ISOLATED THUNDER FOR JUST THE COASTAL COUNTIES DURING THE PRE-DAWN SAT HRS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 330 PM FRIDAY...WET START TO THE WEEKEND WITH A COMPLEX FRONTAL SYSTEM MOVING ACROSS THE COASTAL CAROLINAS. A SERIES OF STRONG UPPER SHORT WAVES MOVING ACROSS EASTERN CONUS WILL POWER THE VERY PROGRESSIVE WEATHER PATTERN WE HAVE BEEN EXPERIENCING LATELY. RAIN WILL BE ONGOING SATURDAY MORNING WITH ALL GUIDANCE IN GOOD AGREEMENT THAT 100 POPS ARE MOST APPROPRIATE TO START OFF THE DAY. MODEL SOUNDINGS SHOW A DEEP...MOIST COLUMN WITH P/W VALUES IN EXCESS OF 1.50 INCHES AND ENOUGH ISENTROPIC LIFT TO WRING OUT AT LEAST MODERATE RAINFALL THROUGH THE MORNING HOURS. SIGNIFICANT RAIN COULD EXTEND WELL INTO THE AFTERNOON HOURS...WITH A LESSER SHORTWAVE POSSIBLY KICKING OFF ANOTHER ROUND OF HEAVIER PRECIPITATION IN THE EVENING HOURS. MIGRATORY HIGH PRESSURE PUSHES ENTIRE SYSTEM OFFSHORE OVERNIGHT...WITH ANY RESIDUAL LIGHT PRECIP HAVING SHUT DOWN BY AROUND DAYBREAK ON SUNDAY. THE HIGH BUILDING IN ON SUNDAY WILL BRIEFLY USHER IN A MUCH DRYER AIRMASS ALTHOUGH COLD ADVECTION WILL BE ON THE WEAK SIDE. MODEL SOUNDINGS SUGGEST A SUNNY DAY...WITH INCREASING CIRRUS OVERNIGHT AS A WARM FRONT APPROACHES FROM THE SOUTH. TEMPERATURES MAY BE TRICKY SIDE ON SATURDAY DUE TO FRONTAL PLACEMENT AND EXTENSIVE PRECIPITATION. MODEL CONSENSUS SUGGESTS A NEARLY 10 DEGREE TEMPERATURE SPREAD BETWEEN THE COASTAL AND INLAND REGIONS...WITH MAXIMUM TEMPERATURES OF AROUND 50 WELL INLAND...AND UPPER 50S ALONG THE COAST. AMPLE SUN AND POSSIBLE DOWNSLOPING ON SUNDAY WILL BRING MAXIMUM TEMPERATURES UP INTO THE MID 60S MOST PLACES. NO WORRIES ABOUT FREEZING TEMPERATURES...WITH LOWS IN THE 40S MOST PLACES BOTH NIGHTS. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 330 PM FRIDAY...HIGH PRESSURE EXTENDING DOWN FROM SYSTEM OVER THE GREAT LAKES MAY REMAIN WEDGED IN THROUGH INLAND CAROLINAS AS DEVELOPING LOW PRESSURE MAKES ITS WAY UP FROM THE GULF COAST MONDAY INTO TUESDAY. LOOKS LIKE SHALLOW NORTHEAST FLOW AT THE SURFACE WILL BE OVERRUN BY INCREASING SOUTHERLY FLOW ALOFT THROUGH LATE MONDAY INTO TUES MORNING. EXPECT CLOUDS TO THICKEN EARLY MONDAY AND PCP TO SPREAD NORTH THROUGH THE DAY. MAY SQUEEZE OUT A DRY DAY ACROSS NORTH CAROLINA. THE PARENT LOW TO THIS SYSTEM WILL MOVE UP THROUGH THE MID WEST INTO THE GREAT LAKES ON TUESDAY. THIS WILL HELP TO ERODE THE WEDGE AND PULL THE LOW OVER THE SOUTHEAST TO THE NORTH BY TUES AFTN. THEREFORE EXPECT BEST ISENTROPIC LIFT THROUGH LATE MON INTO MON NIGHT AND TAPERING OFF THROUGH TUES MORNING. MAY SEE DECENT QPF THROUGH MON INTO EARLY TUES. BY TUES AFTN WINDS WILL SHIFT AROUND TO THE SW TO W ON BACK END OF LOW. EXPECT DRIER AIR TO MAKE ITS WAY IN AT THIS TIME. WINDS ALOFT WILL REMAIN W-SW AS PARENT LOW CUTS OFF AND CONTINUES TO SPIN OVER THE UPPER GREAT LAKES WITH BROAD TROUGH EXTENDING DOWN ACROSS THE EASTERN CONUS THROUGH MID WEEK. OVERALL WEAK HIGH PRESSURE WILL TAKE HOLD OVER AREA THROUGH THE REST OF THE PERIOD WITH GENERALLY DRY FORECAST TUES NIGHT THROUGH FRI. GFS SHOWS ANOTHER SHORTWAVE RIDING ACROSS THE BASE OF THE TROUGH THROUGH NORTH CAROLINA WED NIGHT INTO THURS. THIS MAY PRODUCE SOME CLOUDS AND PCP BUT FOR NOW WILL KEEP MAIN EFFECTS FROM THIS TO OUR NORTH. WITH TROUGH HANGING OVER AREA...CAN NOT RULE OUT THE CHC OF CLOUDS OR PCP AS MINOR PERTURBATIONS MOVE THROUGH BUT FOR NOW...NOT LOOKING AT ANY MAJOR EFFECTS. AS FOR TEMPS...COOLER DAY EXPECTED ON MONDAY WITH TEMPS IN THE 50S IN COOL WEDGE...ESPECIALLY INLAND AREAS. AS WINDS COME AROUND WARMER AND MOISTER AIR COMBINED WITH CLOUDS WILL KEEP TEMPS UP MON NIGHT AND THEN WILL SEE WARMER MORE SEASONABLE TEMPS THROUGH MID WEEK IN S-SW FLOW. FRI MAY COOL OFF AS NW FLOW DEVELOPS ON BACK END OF DEPARTING LOW. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...EXPECT WIDESPREAD IFR/LIFR ACROSS THE TERMINALS THROUGH SATURDAY DUE TO LOWERED CIGS AND REDUCED VISIBILITIES IN RAIN AND FOG. LOWERED CIGS WITH AREAS OF RA AND REDUCED VISIBILITIES DUE TO FOG CONTINUE TO BE WIDESPREAD ACROSS THE AREA...WITH NORTHEAST WINDS AOB 6 KTS. EXPECT MAINLY LIFR CONDITIONS TO CONTINUE OVERNIGHT AND MODELS ARE IN GOOD AGREEMENT. RAIN WILL INCREASE THROUGH THE MORNING HOURS...WHICH WILL ALSO CONTRIBUTE TO REDUCED VISIBILITIES. THOUGH RAIN WILL TAPER OFF INTO SATURDAY EVENING...GIVEN CURRENT FCST SOUNDINGS AND TIME-HEIGHT ANALYSIS...PROJECT IFR CONDITIONS DUE TO LOWERED CIGS AND FOG TO PERSIST THROUGH THE TAIL END OF THE FORECAST PERIOD. NE WIND MAY BRIEFLY BECOME SSW ALONG THE COAST THIS MORNING AS OFFSHORE FRONT NEARS...BUT EXPECT NNE WINDS TO HOLD ACROSS KFLO AND KLBT. WINDS WILL BECOME WSW THROUGHOUT BY EVENING. EXTENDED OUTLOOK...EXPECT MVFR/IFR CONDITIONS OVERNIGHT SATURDAY... BECOMING VFR SUNDAY. RAIN REDEVELOPING MONDAY ENDING TUESDAY MORNING. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM FRIDAY...POSITIONING OF THE COASTAL FRONT WILL BE THE MAIN FOCUS AND PROBLEM OVERNIGHT INTO SATURDAY. BORDERLINE SCA THRESHOLDS WARRANT THE CONTINUATION OF THE SCA INTO SATURDAY. COASTAL FRONT REMAINS JUST OFFSHORE...JUST BEYOND THE OUTER WATERS OF THE ILM COASTAL WATERS. LATEST WINDS AND SEAS AT 41013 AND 41037 BUOYS ARE SE 15 TO 20 KT WITH 5 FT SEAS. LATEST WINDS AND SEAS AT 41110...41038 AND 41024 BUOYS ARE NE TO ENE 10 TO 20 KT WITH SEAS 3 TO 5 FT. SCA CONDITIONS SHOULD BE REALIZED OVERNITE AS THE SFC PG FURTHER TIGHTENS...AND THE COASTAL FRONT GETS PULLED CLOSER TO THE IMMEDIATE COAST IN ADVANCE OF THE LOW APPROACHING FROM THE SW. THE LATEST HRRR SFC WIND FIELDS KEEP THE COASTAL FRONT OVER THE WATERS RATHER THAN BRINGING IT ONSHORE. HAVE GEARED TOWARD THIS SCENARIO...AND HAVE NOW INDICATED THE COASTAL FRONT TO PARTIALLY MOVE ACROSS THE COASTAL WATERS OVERNITE INTO SAT. AS A RESULT... HAVE AD-LIBBED THE CURRENT CWF TEXT TO INDICATE THE DIFFERENCES IN BOTH WINDS AND SEAS IN THE NEAR SHORE...0-10 NM OUT...AND THE OUTER WATERS...10-20 NM OUT. HAVE ALSO INDICATED ISOLATED CONVECTION AFTER MIDNIGHT INTO THE DAYLIGHT HRS OF SAT DUE TO DYNAMICS FROM IMPULSES ALOFT INTERACTING WITH THE COASTAL FRONT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 330 PM FRIDAY...COMPLEX FRONTAL SYSTEM OVER THE COASTAL CAROLINAS WILL BRING SOUTH TO SOUTHWEST WINDS OF 15 TO 20 KTS AND 4 TO 6 FT SEAS TO THE WATERS SATURDAY MORNING...WITH CONDITIONS GRADUALLY IMPROVING THROUGH THE DAY. FRONTAL SYSTEM WILL PUSH OFFSHORE OVERNIGHT...WITH WINDS TURNING OFFSHORE AFTER MIDNIGHT. RESULTING LIMITED FETCH WILL ALLOW SEAS TO DROP BACK INTO THE 2 TO 4 FT RANGE OVERNIGHT. RAINFALL ON SATURDAY MAY BE HEAVY AT TIMES...RESTRICTING VISIBILITY SIGNIFICANTLY. FAIRLY BENIGN3CONDITIONS WILL CONTINUE INTO SUNDAY WITH SEAS MAINLY IN THE 2 TO 4 FT RANGE AND LIGHT WINDS DURING THE DAYTIME HOURS. WINDS WILL VEER TO THE NE OVERNIGHT AS A WARM FRONT APPROACHES FROM THE SOUTH...INCREASING TO 10 TO 15 KTS BY DAYBREAK ON MONDAY. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 330 PM FRIDAY...GRADIENT WILL TIGHTEN THROUGH MONDAY AS HIGH PRESSURE EXTENDING DOWN FROM THE GREAT LAKES SHIFTS EAST WHILE LOW PRESSURE SYSTEM MAKES ITS WAY UP FROM THE GULF COAST. EXPECT N-NE WINDS EARLY MONDAY SHIFTING AROUND AND INCREASING AS WARM FRONT/COASTAL TROUGH PUSHES INLAND BY TUESDAY. SEAS AROUND 2 TO 3 FT MON MORNING WILL INCREASE THROUGH THE DAY WITH INCREASING NE TO E FLOW REACHING UP TO A SOLID 20 KTS THROUGH MON NIGHT. THIS WILL PUSH SEAS UP ABOVE SCA THRESHOLDS BY MIDNIGHT AND REMAINING 6 TO 8 FT IN OUTER WATERS AND 4 TO 6 FT NEAR SHORE THROUGH TUES MORNING. AS THE LOW LIFTS OFF TO THE NORTH LATE TUESDAY THE WINDS WILL VEER AROUND TO THE W-SW REMAINING THAT WAY THROUGH MID WEEK. THE WEAKENING OFF SHORE FLOW WILL ALLOW SEAS TO SUBSIDE BELOW SCA THRESHOLDS BY LATE TUES DROPPING FURTHER TO 2 TO 4 FT THROUGH WEDNESDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR AMZ254-256. SMALL CRAFT ADVISORY UNTIL 6 PM EST SATURDAY FOR AMZ250-252. && $$ NEAR TERM...DCH SHORT TERM...REK LONG TERM...RGZ AVIATION...SGL/RJD
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1112 PM EST FRI FEB 22 2013 .SYNOPSIS... ISOLATED AREAS OF LIGHT RAIN WILL CONTINUE THIS AFTERNOON. MODERATE TO HEAVY RAIN IS EXPECTED FOR THE OVERNIGHT HOURS AND INTO SATURDAY. HIGH PRESSURE WILL BRING IN DRY AIR ON SUNDAY LASTING INTO EARLY MONDAY. ANOTHER ROUND OF RAINFALL WILL OCCUR MONDAY INTO TUESDAY. THE MIDDLE TO THE END OF NEXT WEEK WILL FEATURE DRY AIR AND A COOLING TREND. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 1045 PM FRIDAY...CONTINUED LACK OF RADAR ECHOES ACROSS THE FA AT THE MOMENT. THE RADAR RETURNS FOR THE MOST PART OVER LAND WERE NOT REACHING THE GROUND VIA SFC OBSERVATIONS. THINKING REMAINS THAT THE FA WILL FILL IN WITH LIGHT TO MODERATE STRATIFORM TYPE RAINS AFTER MIDNIGHT...MAINLY TOWARD DAYBREAK SAT. AS A RESULT...OVERNITE AND DAYLIGHT SAT POPS HAVE BEEN ADJUSTED. LATEST PROGS KEEP THE COASTAL FRONT ALONG THE IMMEDIATE COAST...WITH VERY LITTLE INLAND MOVEMENT. IN FACT...LATEST HRRR PROGGED SFC WIND FIELD KEEPS A NORTHERLY COMPONENT IN THE WINDS ACROSS THE CWA OVERNITE INTO SAT. TONIGHTS MINS...NOT THE 24 HR MIN...WILL LIKELY OCCUR AROUND OR JUST AFTER MIDNIGHT...FOLLOWED BY A STEADY OR EVEN A SLOW/SLIGHT RISE IN TEMPS DURING THE PRE- DAWN HRS ESPECIALLY ALONG THE IMMEDIATE COAST. WEAK IMPULSES WITHIN SW-WSW FLOW ALOFT MAY PROVIDE ENOUGH DYNAMICS TO AID THE DEVELOPMENT OF ISOLATED CONVECTION ALONG THE COASTAL FRONT. HAVE INDICATED ISOLATED THUNDER FOR JUST THE COASTAL COUNTIES DURING THE PRE-DAWN SAT HRS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 3:30 PM FRIDAY...WET START TO THE WEEKEND WITH A COMPLEX FRONTAL SYSTEM MOVING ACROSS THE COASTAL CAROLINAS. A SERIES OF STRONG UPPER SHORT WAVES MOVING ACROSS EASTERN CONUS WILL POWER THE VERY PROGRESSIVE WEATHER PATTERN WE HAVE BEEN EXPERIENCING LATELY. RAIN WILL BE ONGOING SATURDAY MORNING WITH ALL GUIDANCE IN GOOD AGREEMENT THAT 100 POPS ARE MOST APPROPRIATE TO START OFF THE DAY. MODEL SOUNDINGS SHOW A DEEP...MOIST COLUMN WITH P/W VALUES IN EXCESS OF 1.50 INCHES AND ENOUGH ISENTROPIC LIFT TO WRING OUT AT LEAST MODERATE RAINFALL THROUGH THE MORNING HOURS. SIGNIFICANT RAIN COULD EXTEND WELL INTO THE AFTERNOON HOURS...WITH A LESSER SHORTWAVE POSSIBLY KICKING OFF ANOTHER ROUND OF HEAVIER PRECIPITATION IN THE EVENING HOURS. MIGRATORY HIGH PRESSURE PUSHES ENTIRE SYSTEM OFFSHORE OVERNIGHT...WITH ANY RESIDUAL LIGHT PRECIP HAVING SHUT DOWN BY AROUND DAYBREAK ON SUNDAY. THE HIGH BUILDING IN ON SUNDAY WILL BRIEFLY USHER IN A MUCH DRYER AIRMASS ALTHOUGH COLD ADVECTION WILL BE ON THE WEAK SIDE. MODEL SOUNDINGS SUGGEST A SUNNY DAY...WITH INCREASING CIRRUS OVERNIGHT AS A WARM FRONT APPROACHES FROM THE SOUTH. TEMPERATURES MAY BE TRICKY SIDE ON SATURDAY DUE TO FRONTAL PLACEMENT AND EXTENSIVE PRECIPITATION. MODEL CONSENSUS SUGGESTS A NEARLY 10 DEGREE TEMPERATURE SPREAD BETWEEN THE COASTAL AND INLAND REGIONS...WITH MAXIMUM TEMPERATURES OF AROUND 50 WELL INLAND...AND UPPER 50S ALONG THE COAST. AMPLE SUN AND POSSIBLE DOWNSLOPING ON SUNDAY WILL BRING MAXIMUM TEMPERATURES UP INTO THE MID 60S MOST PLACES. NO WORRIES ABOUT FREEZING TEMPERATURES...WITH LOWS IN THE 40S MOST PLACES BOTH NIGHTS. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3:30 PM FRIDAY...HIGH PRESSURE EXTENDING DOWN FROM SYSTEM OVER THE GREAT LAKES MAY REMAIN WEDGED IN THROUGH INLAND CAROLINAS AS DEVELOPING LOW PRESSURE MAKES ITS WAY UP FROM THE GULF COAST MONDAY INTO TUESDAY. LOOKS LIKE SHALLOW NORTHEAST FLOW AT THE SURFACE WILL BE OVERRUN BY INCREASING SOUTHERLY FLOW ALOFT THROUGH LATE MONDAY INTO TUES MORNING. EXPECT CLOUDS TO THICKEN EARLY MONDAY AND PCP TO SPREAD NORTH THROUGH THE DAY. MAY SQUEEZE OUT A DRY DAY ACROSS NORTH CAROLINA. THE PARENT LOW TO THIS SYSTEM WILL MOVE UP THROUGH THE MID WEST INTO THE GREAT LAKES ON TUESDAY. THIS WILL HELP TO ERODE THE WEDGE AND PULL THE LOW OVER THE SOUTHEAST TO THE NORTH BY TUES AFTN. THEREFORE EXPECT BEST ISENTROPIC LIFT THROUGH LATE MON INTO MON NIGHT AND TAPERING OFF THROUGH TUES MORNING. MAY SEE DECENT QPF THROUGH MON INTO EARLY TUES. BY TUES AFTN WINDS WILL SHIFT AROUND TO THE SW TO W ON BACK END OF LOW. EXPECT DRIER AIR TO MAKE ITS WAY IN AT THIS TIME. WINDS ALOFT WILL REMAIN W-SW AS PARENT LOW CUTS OFF AND CONTINUES TO SPIN OVER THE UPPER GREAT LAKES WITH BROAD TROUGH EXTENDING DOWN ACROSS THE EASTERN CONUS THROUGH MID WEEK. OVERALL WEAK HIGH PRESSURE WILL TAKE HOLD OVER AREA THROUGH THE REST OF THE PERIOD WITH GENERALLY DRY FORECAST TUES NIGHT THROUGH FRI. GFS SHOWS ANOTHER SHORTWAVE RIDING ACROSS THE BASE OF THE TROUGH THROUGH NORTH CAROLINA WED NIGHT INTO THURS. THIS MAY PRODUCE SOME CLOUDS AND PCP BUT FOR NOW WILL KEEP MAIN EFFECTS FROM THIS TO OUR NORTH. WITH TROUGH HANGING OVER AREA...CAN NOT RULE OUT THE CHC OF CLOUDS OR PCP AS MINOR PERTURBATIONS MOVE THROUGH BUT FOR NOW...NOT LOOKING AT ANY MAJOR EFFECTS. AS FOR TEMPS...COOLER DAY EXPECTED ON MONDAY WITH TEMPS IN THE 50S IN COOL WEDGE...ESPECIALLY INLAND AREAS. AS WINDS COME AROUND WARMER AND MOISTER AIR COMBINED WITH CLOUDS WILL KEEP TEMPS UP MON NIGHT AND THEN WILL SEE WARMER MORE SEASONABLE TEMPS THROUGH MID WEEK IN S-SW FLOW. FRI MAY COOL OFF AS NW FLOW DEVELOPS ON BACK END OF DEPARTING LOW. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... AS OF 00Z...WIDESPREAD MVFR/IFR THIS EVENING WILL GRADUALLY DETERIORATE TO IFR/LIFR ACROSS THE ENTIRE AREA OVERNIGHT AND THROUGH SATURDAY EARLY EVENING. CONDITIONS MAY IMPROVE TO MVFR TOWARDS THE END OF THE TAF PERIOD. LOWERED CIGS WITH AREAS OF -DZ AND REDUCED VISIBILITIES DUE TO FOG ARE SPREAD ABOUT THE ENTIRE AREA THIS EVENING...WITH EAST-NORTHEAST WINDS AOB 10 KTS. EXPECT CONDITIONS TO CONTINUE TO DETERIORATE INTO THE EARLY OVERNIGHT HOURS TO IFR/LIFR...WITH MODELS IN GOOD AGREEMENT. DRIER AIR WITHIN THE MID LEVELS HAS INHIBITED WIDESPREAD RA/SHRA AS PREVIOUSLY ANTICIPATED...THUS HAVE OPTED TO ONLY INCLUDE -DZ/VCSH FOR THE OVERNIGHT HOURS. SATURDAY MORNING...ANTICIPATE IFR/LIFR TO CONTINUE WITH LOWERED CIGS AND AREAS OF FOG. RAIN CHANCES WILL INCREASE AS WELL ON SATURDAY...WHICH WILL ALSO CONTRIBUTE TO REDUCED VISIBILITIES. GIVEN CURRENT FCST SOUNDINGS AND TIME-HEIGHT ANALYSIS...PROJECT THESE CONDITIONS TO CONTINUE THROUGH SATURDAY EVENING...THOUGH COULD POTENTIALLY SEE CONDITIONS IMPROVE TO MVFR BEFORE THE END OF VALID FORECAST. WINDS THROUGHOUT THE DAY ON SATURDAY WILL GRADUALLY SHIFT TO GENERALLY SOUTH ALONG THE COAST...WHILE PERSISTING NORTH-NORTHEAST INLAND. EXTENDED OUTLOOK...EXPECT MVFR/IFR CONDITIONS SATURDAY NIGHT. BECOMING VFR SUNDAY. RAIN REDEVELOPING MONDAY ENDING TUESDAY MORNING. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM FRIDAY...POSITIONING OF THE COASTAL FRONT WILL BE THE MAIN FOCUS AND PROBLEM OVERNIGHT INTO SATURDAY. BORDERLINE SCA THRESHOLDS WARRANT THE CONTINUATION OF THE SCA INTO SATURDAY. COASTAL FRONT REMAINS JUST OFFSHORE...JUST BEYOND THE OUTER WATERS OF THE ILM COASTAL WATERS. LATEST WINDS AND SEAS AT 41013 AND 41037 BUOYS ARE SE 15 TO 20 KT WITH 5 FT SEAS. LATEST WINDS AND SEAS AT 41110...41038 AND 41024 BUOYS ARE NE TO ENE 10 TO 20 KT WITH SEAS 3 TO 5 FT. SCA CONDITIONS SHOULD BE REALIZED OVERNITE AS THE SFC PG FURTHER TIGHTENS...AND THE COASTAL FRONT GETS PULLED CLOSER TO THE IMMEDIATE COAST IN ADVANCE OF THE LOW APPROACHING FROM THE SW. THE LATEST HRRR SFC WIND FIELDS KEEP THE COASTAL FRONT OVER THE WATERS RATHER THAN BRINGING IT ONSHORE. HAVE GEARED TOWARD THIS SCENARIO...AND HAVE NOW INDICATED THE COASTAL FRONT TO PARTIALLY MOVE ACROSS THE COASTAL WATERS OVERNITE INTO SAT. AS A RESULT... HAVE AD-LIBBED THE CURRENT CWF TEXT TO INDICATE THE DIFFERENCES IN BOTH WINDS AND SEAS IN THE NEAR SHORE...0-10 NM OUT...AND THE OUTER WATERS...10-20 NM OUT. HAVE ALSO INDICATED ISOLATED CONVECTION AFTER MIDNIGHT INTO THE DAYLIGHT HRS OF SAT DUE TO DYNAMICS FROM IMPULSES ALOFT INTERACTING WITH THE COASTAL FRONT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3:30 PM FRIDAY...COMPLEX FRONTAL SYSTEM OVER THE COASTAL CAROLINAS WILL BRING SOUTH TO SOUTHWEST WINDS OF 15 TO 20 KTS AND 4 TO 6 FT SEAS TO THE WATERS SATURDAY MORNING...WITH CONDITIONS GRADUALLY IMPROVING THROUGH THE DAY. FRONTAL SYSTEM WILL PUSH OFFSHORE OVERNIGHT...WITH WINDS TURNING OFFSHORE AFTER MIDNIGHT. RESULTING LIMITED FETCH WILL ALLOW SEAS TO DROP BACK INTO THE 2 TO 4 FT RANGE OVERNIGHT. RAINFALL ON SATURDAY MAY BE HEAVY AT TIMES...RESTRICTING VISIBILITY SIGNIFICANTLY. FAIRLY BENIGN3CONDITIONS WILL CONTINUE INTO SUNDAY WITH SEAS MAINLY IN THE 2 TO 4 FT RANGE AND LIGHT WINDS DURING THE DAYTIME HOURS. WINDS WILL VEER TO THE NE OVERNIGHT AS A WARM FRONT APPROACHES FROM THE SOUTH...INCREASING TO 10 TO 15 KTS BY DAYBREAK ON MONDAY. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 3:30 PM FRIDAY...GRADIENT WILL TIGHTEN THROUGH MONDAY AS HIGH PRESSURE EXTENDING DOWN FROM THE GREAT LAKES SHIFTS EAST WHILE LOW PRESSURE SYSTEM MAKES ITS WAY UP FROM THE GULF COAST. EXPECT N-NE WINDS EARLY MONDAY SHIFTING AROUND AND INCREASING AS WARM FRONT/COASTAL TROUGH PUSHES INLAND BY TUESDAY. SEAS AROUND 2 TO 3 FT MON MORNING WILL INCREASE THROUGH THE DAY WITH INCREASING NE TO E FLOW REACHING UP TO A SOLID 20 KTS THROUGH MON NIGHT. THIS WILL PUSH SEAS UP ABOVE SCA THRESHOLDS BY MIDNIGHT AND REMAINING 6 TO 8 FT IN OUTER WATERS AND 4 TO 6 FT NEAR SHORE THROUGH TUES MORNING. AS THE LOW LIFTS OFF TO THE NORTH LATE TUESDAY THE WINDS WILL VEER AROUND TO THE W-SW REMAINING THAT WAY THROUGH MID WEEK. THE WEAKENING OFF SHORE FLOW WILL ALLOW SEAS TO SUBSIDE BELOW SCA THRESHOLDS BY LATE TUES DROPPING FURTHER TO 2 TO 4 FT THROUGH WEDNESDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR AMZ254-256. SMALL CRAFT ADVISORY UNTIL 6 PM EST SATURDAY FOR AMZ250-252. && $$ SYNOPSIS...REK NEAR TERM...DCH SHORT TERM...REK LONG TERM...RGZ AVIATION...SGL
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
326 AM CST SAT FEB 23 2013 .SHORT TERM (TODAY-MONDAY NIGHT)... INITIALLY CLOUDS AND FOG WILL BE THE CONCERN. OTHERWISE...CLOUDS AND LIGHT SNOW CHANCES WILL BE THE CHALLENGE. 00Z MODELS IN DECENT AGREEMENT ALTHOUGH WITH DETAIL DIFFERENCES SUNDAY INTO MONDAY. WILL USE A BLEND FOR THIS FORECAST. THE FORECAST AREA (FA) IS CURRENTLY STUCK WITHIN A VERY WEAK FLOW ENVIRONMENT. LOW CLOUDS EXIST ALONG AND EAST OF THE VALLEY. THESE CLOUDS SEEM TO BE OCCURRING WHERE MODELS SHOW 925MB WINDS CALM TO 5 KNOTS. WILL USE THE RAP AS GUIDANCE FOR WHEN SKIES WILL CLEAR FROM WEST TO EAST (AS LOW LEVEL FLOW INCREASES). THIS SLOWS THE CLEARING TREND TODAY. PATCHY DENSE FOG HAS OCCURRED WITHIN THIS WEAK FLOW ENVIRONMENT...BUT 1/4SM VSBY HAS NOT BEEN CONSISTENT FROM HOUR TO HOUR. WILL KEEP PATCHY FOG IN THE GRIDS THROUGH THE MORNING HOURS WHERE CLOUDS (WEAK MIXING) IS EXPECTED...AND MONITOR FOG CONDITIONS. FOR SUNDAY INTO MONDAY...SOUTHERN STREAM ENERGY WILL REMAIN WELL SOUTH OF THE REGION...BUT THERE WILL BE A WEAK NORTHERN STREAM WAVE THAT AFFECTS THE REGION DURING THIS TIME. THE ECMWF IS STRONGER WITH THE RIDGING TO THE EAST...AND KEEPS THIS FEATURE WEST OF OTHER MODELS (WESTERN DAKOTAS VS EASTERN DAKOTAS) AS IT DROPS TO THE SOUTH AND INTO THE SOUTHERN STREAM WAVE. THE MAIN AFFECT OF THIS WAVE WILL LIKELY BE CLOUD COVER...BUT LIGHT SNOW IS ALSO POSSIBLE. THE EXACT LOCATION OF THIS WAVE WILL DETERMINE WHERE/WHEN THE LIGHT SNOW OCCURS. IF THE ECMWF IS CORRECT ACCUMULATIONS WILL BE MAYBE A DUSTING...AND IF THE OTHER MODELS ARE CORRECT ACCUMULATIONS COULD BE AN INCH OR TWO. WILL MAINTAIN PREVIOUS FORECAST OF LOW POPS ACROSS THE WESTERN FA WITH ONLY A DUSTING POSSIBLE (AS PMDHMD PREFERS THE ECMWF). .LONG TERM (TUESDAY-FRIDAY)... MODELS CONTINUE TO BE IN FAIR AGREEMENT WITH A QUIET WEATHER PATTERN FOR THE CWFA FOR THE EXTENDED TIME FRAME WITH A SPLIT FLOW IN THE STORM TRACK. 500MB FLOW WILL TRANSITION FROM AN ARKANSAS CUTOFF LOW WITH THE NWERLY ORIENTED TROUGH THROUGH THE NORTHERN US ROCKIES INTO A POSITIVE PNA PATTERN...WESTERN RIDGE AND EASTERN TROUGH ACROSS THE CONUS...BY THE END OF THE PERIOD. WITH LITTLE UPPER LEVEL ENERGY MOVING ACROSS THE AREA ONLY SLIGHT CHC FOR POPS WITH -SN POSSIBLE TUE AND WED ACROSS THE SOUTH AND EAST ZONES WITH TEMPS NEAR END OF FEB NORMALS. && .AVIATION... IFR/LIFR CIGS/VSBY ALONG AND EAST OF THE RED RIVER VALLEY ARE EXPECTED TO SLOWLY IMPROVE FROM WEST TO EAST TODAY. THE MAIN QUESTION IS WHEN THIS WILL OCCUR. THE THOUGHT IS THAT AS LONG AS LOW LEVEL FLOW REMAINS WEAK THE LOW CIGS WILL REMAIN. WILL FOLLOW MODEL 925MB WINDS ABOVE 5 KNOTS FOR INCREASED LOW LEVEL MIXING AND CLEARING. THIS CLEARS THE VALLEY TAFS LATE MORNING...AND THE EASTERN FA (KBJI) SOMETIME TOWARD SUNRISE ON SUNDAY. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG/JK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1203 AM CST SAT FEB 23 2013 .UPDATE...FOR 06Z TAFS... && .AVIATION... AN AXIS OF LIGHT SHOWERS WILL REMAIN TO THE SOUTH AND EAST OF MIDDLE TENNESSEE TONIGHT. A WEAK FRONT HAS MOVED JUST EAST OF NASHVILLE INFLUENCING WINDS TO REMAIN OUT OF THE WNW FOR CKV AND BNA FOR THE REMAINDER OF THE FORECAST PERIOD. THE BOUNDARY WILL CONTINUE TO SLOWLY MOVE EAST DURING THE EARLY MORNING HOURS...KEEPING CSV IN AN AREA OF LIGHT WINDS AND FOG...WHICH COULD POSSIBLY REDUCE VISIBILITY TO A MILE AT TIMES. CIGS COULD BRIEFLY LOWER TO IFR CONDITIONS AT BNA EARLY SATURDAY MORNING. CSV CIGS ARE ALSO EXPECTED TO REMAIN WITHIN LIFR CONDITIONS FOR MOST OF THE EARLY MORNING HOURS UNTIL THE BOUNDARY FINALLY MOVES FARTHER EAST OF THE MID STATE LATER SATURDAY MORNING...WITH CONDITIONS IMPROVING THROUGHOUT THE DAY ON SATURDAY. && .PREV DISCUSSION... /ISSUED 807 PM CST FRI FEB 22 2013/ UPDATE... LATEST REGIONAL RADAR IMAGERY SHOWS SCATTERED RAIN ACROSS NORTHERN MISSISSIPPI AND ALABAMA INTO EAST TENNESSEE. ACTIVITY HAS BEEN REMAINING TO THE SOUTHEAST OF THE CWA SO FAR...AND APPEARS THIS TREND WILL CONTINUE THROUGH MUCH OF THE NIGHT WITH ONLY THE FAR EASTERN AND SOUTHEASTERN ZONES LIKELY TO BE AFFECTED BY ANY PRECIP. WITH SHORT TERM GUIDANCE INCLUDING THE HRRR AND 00Z NAM AGREEING WITH THIS SCENARIO...WILL TRIM POPS BACK FURTHER TOWARDS THE SOUTHEAST. WILL ALSO KEEP IN MENTION OF PATCHY FOG OVER THE SOUTHEAST HALF OF THE CWA AS DEWPOINT DEPRESSIONS ARE ALREADY LOW...AND WILL BE SEVERAL HOURS BEFORE APPROACHING COLD FRONT OVER NORTHWEST ZONES REACHES THIS AREA. REST OF FORECAST APPEARS TO BE ON TRACK. PREV DISCUSSION... /ISSUED 641 PM CST FRI FEB 22 2013/ UPDATE...FOR 00Z TAFS... AVIATION... MAINLY VFR CONDITIONS THIS EVENING FOR CKV AND BNA. AFTER MIDNIGHT CEILINGS ARE EXPECTED TO LOWER TO MVFR CONDITIONS...WITH IFR CONDITIONS POSSIBLE IN NASHVILLE AS CIGS DROP BELOW 1000 FEET IN THE EARLY MORNING HOURS. CONDITIONS AT CSV REMAIN WITHIN IFR CONDITIONS WITH CONDITIONS DETERIORATING AS THE NIGHT PROGRESSES. CEILINGS ARE FORECAST TO CONTINUE LOWERING THIS EVENING AS A BAND OF MOISTURE MOVES JUST SOUTH AND EAST OF THE MID STATE. VIS AT CSV MAY BE REDUCED TO 1 MILE OR LESS SATURDAY MORNING DUE TO FOG. CONDITIONS SHOULD IMPROVE CLOSER TO NOON ON SATURDAY AS A FRONT PASSES THROUGH THE AREA. PREV DISCUSSION... /ISSUED 320 PM CST FRI FEB 22 2013/ DISCUSSION... TEMPS DROP OFF CONSIDERABLY TO THE WEST OF NASHVILLE BEHIND THE COLD FRONT. THIS BOUNDARY IS RUNNING PARALLEL TO THE UPPER FLOW BUT WILL SLOWLY MOVE THROUGH AND WILL REACH EAST TN TONIGHT. THE BOUNDARY WILL THEN SLOW DOWN AND STALL. SFC ENERGY WILL THEN LIFT NE ALONG THE BOUNDARY AND SPREAD MOISTURE NORTHWARD. LOOKS AS THOUGH THE MOISTURE WILL FOR THE MOST PART STAY SOUTH OF MIDDLE TN. ALTHOUGH...SOME SHOWER ACTIVITY COULD REACH THE PLATEAU AND SRN AREAS OVERNIGHT. WILL INCLUDE LOW POPS FOR EASTERN AND SOUTHERN PORTIONS. OTHERWISE...DESPITE THE FROPA AND SOME LOWERING DEW POINTS...DEW POINT DEPRESSIONS WILL BE RATHER LOW BY 12Z...PARTICULARLY ACROSS THE EASTERN HALF OF THE CWA. WILL ALSO INCLUDE SOME PATCHY LATE NIGHT FOG. ON SATURDAY...SFC HIGH WILL BUILD IN WITH SOME DRIER AIR WINNING OUT. THIS TREND WILL CONTINUE INTO SUNDAY...AND WITH AMPLIFIED HEIGHTS...SHOULD SEE TEMPS BACK UP INTO THE 50S FOR BOTH DAYS. IN THE EXT FCST...MODELS ARE CONTINUING TO TREND TOWARD A COLDER AND SOMEWHAT UNSETTLED PATTERN. UPPER LEVEL TROUGHING IS EXPECTED WITH SEVERAL DISTURBANCES MOVING THROUGH THE AREA. THE FIRST SYSTEM WILL BE ON MONDAY WITH A POTENT NEGATIVELY TILTED UPPER LOW AXIS. THIS FEATURE WILL PASS NORTH OF TN AND WILL DRAG AN ASSOCIATED FROPA THROUGH ON TUESDAY. RAIN PROBABILITIES LOOK HIGH FOR MONDAY INTO TUESDAY. SYNOPTIC FEATURES SUPPORT THE POTENTIAL FOR SOME WRAP AROUND SNOWFALL. HOWEVER...MODEL SFC TEMPS LOOK TOO WARM AND EVEN A 5 DEGREE UNDERCUT WILL NOT SUPPORT SUFFICIENTLY LOW ENOUGH FREEZING LEVEL SUPPORT. THUS...WILL LEAN TOWARD MOSTLY RAIN FOR TUESDAY. WED NT INTO THU...NEXT IMPULSE TO MOVE THROUGH. MODELS CONVERGE TO SUPPORT TEMPS THAT WILL BE COLD ENOUGH TO SUPPORT AM RAINFALL/SNOWFALL...RAIN IN AFTERNOON. SYSTEM DOES NOT CARRY AN ABUNDANCE OF ORGANIZATION SO WILL KEEP POPS LOW. GFS THEN LEANS TOWARD YET ANOTHER DISTURBANCE FOR FRIDAY. WILL OPT TO KEEP A FLURRIES OR LIGHT SNOW SHOWERS GOING THU NT AD FRIDAY. FOR THE EXT TEMPS...IT WILL BE DO OR DIE TIME VERSUS THE GUIDANCE. MEX IS CARRYING HIGHS OF 45 TO 50 FOR BNA. THE MODELS ARE ALL CONVERGING ON LOW HEIGHTS...CLOUDS AND SOME PRECIP...AD 850 MB TEMPS OF UP TO -5 TO -10. WILL ROLL THE DICE AND UNDERCUT THE MEX NUMBERS DECISIVELY. PERHAPS JUST A SLIGHT UNDERCUT ON OVERNIGHT LOWS. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 11
AREA FORECAST DISCUSSION
NWS SPOKANE WA
947 PM PST Fri Feb 22 2013 .SYNOPSIS...An upper level trough will move through the Pacific Northwest tonight and exit the region early Saturday morning. Pacific Northwest today and tonight. This will result in windy conditions and moderate snow in the mountains. Mountain snow showers will likely linger into Saturday afternoon. A short break in the active weather is expected Saturday night and Sunday, before the next in a series of frontal systems brings increasing chances for rain and snow to the region on Monday. This active late winter weather pattern will continue through the next week. && .DISCUSSION... Upon further investigation concerning a small localized vorticity maximum quite evident rotating around on the satellite and radar imagery as it moves slowly along eastward in close proximity to the Southern British Columbia border and how the latest HRRR shows it to remain intact as it does so through at least 12Z Instead of ending the Winter storm warnings that were to expire in that location I have extended them to 4AM and will reword them to address this more intense but yet localized and complex convective snowfall resulting from it as it passes...since snow levels should continue to crash and allow for some accumulation to valley floors. /Pelatti && .AVIATION... 06Z TAFS: Jet stream associated with passing cold front and cold and unstable airmass sagging down over the aviation area will keep robust and gusty surface wind at many of the aviation sites and possibly some low level wind shear as well as wind aloft is quite strong. Snow levels lower and the probability of snow showers decreases as if they occur they will be highly localized so as not to cause too many drastic drops in ceilings and no widespread impact on ceilings either. /Pelatti && .PRELIMINARY POINT TEMPS/POPS... Spokane 29 40 25 36 29 39 / 10 20 10 20 30 70 Coeur d`Alene 30 38 26 36 30 38 / 10 30 10 20 30 70 Pullman 31 40 26 39 29 41 / 40 50 20 20 30 70 Lewiston 35 48 31 46 33 48 / 10 50 20 10 10 60 Colville 28 42 24 39 29 40 / 30 20 10 20 50 70 Sandpoint 29 38 25 35 30 36 / 70 50 10 30 40 70 Kellogg 29 37 26 34 28 37 / 50 80 20 30 30 60 Moses Lake 30 50 27 46 32 47 / 0 10 0 10 50 30 Wenatchee 30 47 28 43 31 43 / 10 10 0 10 40 30 Omak 23 40 19 35 25 38 / 0 10 0 10 50 60 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Wind Advisory until 4 PM PST Saturday for Coeur d`Alene Area- Idaho Palouse. Winter Storm Warning until 7 PM PST Saturday for Central Panhandle Mountains. Winter Weather Advisory until 7 PM PST Saturday for Lewis and Southern Nez Perce Counties. Winter Storm Warning until 4 AM PST Saturday for Northern Panhandle. WA...Winter Weather Advisory until 10 AM PST Saturday for East Slopes Northern Cascades. Wind Advisory until 4 PM PST Saturday for Lower Garfield and Asotin Counties-Spokane Area-Upper Columbia Basin- Washington Palouse. Winter Storm Warning until 4 AM PST Saturday for Northeast Mountains. Winter Storm Warning until 7 PM PST Saturday for Northeast Blue Mountains. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
319 AM CST SAT FEB 23 2013 .SHORT TERM...TODAY THROUGH MONDAY NIGHT 319 AM CST SAT FEB 23 2013 FORECAST CHALLENGES GOING THROUGH EARLY NEXT WEEK REVOLVE AROUND WHEN THE FLURRIES/SKIES CLEAR OUT TODAY/TONIGHT ALONG WITH WHEN THE NEXT ROUND OF LIGHT SNOW MAY MOVE IN ON MONDAY. CYCLONIC FLOW FROM THE SURFACE THROUGH THE UPPER ATMOSPHERE WILL LINGER ACROSS THE REGION FOR MUCH OF TODAY BEFORE A SURFACE TO UPPER LEVEL RIDGE AXIS PROPAGATES IN FROM THE WEST TONIGHT. WITH THE CYCLONIC FLOW HANGING ON FOR MUCH OF TODAY...EXPECT THAT THE CLOUD COVER AND FLURRIES/SNOW SHOWERS WILL CONTINUE AS WELL AND THAT THE DRY AIR TO THE SOUTHWEST WILL STRUGGLE TO MOVE IN. BY 00Z TONIGHT...THE 23.07Z RAP HAS THE SURFACE RIDGE ALIGNED ALONG THE MISSISSIPPI RIVER...SO AT LEAST EXPECT THAT THE FLURRIES WILL HAVE ENDED BY THEN ALONG AND WEST OF THE RIVER. HOWEVER...CLOUD COVER MAY LINGER WITH THE UPPER RIDGE STILL IN THE DAKOTAS. HAVE PLAYED CLOUD COVER A BIT ON THE PESSIMISTIC SIDE THROUGH TONIGHT AS A RESULT. BEYOND THIS THE PATTERN IS FAIRLY QUIET THROUGH THE REST OF THE WEEKEND AS THE RIDGE SHIFTS TO THE EAST WITH TEMPERATURES AND CLOUD COVER THE ONLY ISSUES TO CONTEND WITH. THERE IS NOT MUCH IN THE WAY OF LOW LEVEL COLD AIR ADVECTION KICKING IN BEHIND THIS SYSTEM...SO EXPECT THAT TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH MONDAY NIGHT. THE FOCUS THEN GOES TO THE NEXT SYSTEM THAT COULD IMPACT THE AREA WHICH IS A COMBINATION OF A NORTHERN STREAM WEAKENING MID LEVEL SHORT WAVE TROUGH AND A SOUTHERN STREAM DEEPENING LOW. THE TREND CONTINUES TO BE TO GO SLOWER WITH THE NORTHERN STREAM SHORT WAVE AS A BLOCKING RIDGE ALONG THE ATLANTIC COAST STALLS OUT THE FLOW. THE SURFACE REFLECTION FROM THIS SYSTEM IS A TROUGH THAT TRACKS ACROSS THE DAKOTAS AND STALLS ACROSS MINNESOTA AS THE SOUTHERN STREAM SYSTEM STARTS TO DEEPEN. THE 23.00Z GFS IS THE MOST ROBUST WITH QPF EXTENDING NORTH ALONG THIS SURFACE TROUGH WHILE THE REST OF THE GUIDANCE IS DRY. THEREFORE...HAVE BACKED OFF ON PRECIPITATION CHANCES FOR MONDAY NIGHT AND KEPT THEM RELEGATED TO PORTIONS OF SOUTH CENTRAL MINNESOTA INTO NORTHEAST IOWA. .LONG TERM...TUESDAY THROUGH FRIDAY 319 AM CST SAT FEB 23 2013 THIS AFOREMENTIONED SOUTHERN STREAM SYSTEM APPEARS TO BE COMING TOGETHER BY TUESDAY WITH THE 23.00Z GUIDANCE LOCKING IN ON A MORE SOUTHERN TRACK WITH THIS SURFACE LOW. THE 23.00Z GFS/ECMWF/GEM ALL ADVERTISE THIS LOW RUNNING FROM ST LOUIS OVER TO INDIANAPOLIS TUESDAY WHICH SHOULD KEEP THE MAIN BAND OF SNOW OFF TO THE SOUTHEAST. THE 23.00Z GFS IS FURTHEST TO THE NORTHWEST WHILE THE GEM/ECMWF ARE NEARLY IDENTICAL WITH THEIR TRACK. HAVE BACKED OFF ON SNOW CHANCES FOR TUESDAY ACROSS SOUTHWEST WISCONSIN AS A RESULT. AFTER THIS SYSTEM MOVES THROUGH...ANOTHER MID LEVEL TROUGH WILL DIG DOWN THROUGH THE NORTHWEST FLOW AND REINFORCE THE CUT OFF CLOSED LOW ACROSS THE EASTERN US. THIS WILL KEEP CYCLONIC FLOW IN PLACE ACROSS THE REGION THROUGH THURSDAY WITH SOME LIGHT SNOW POSSIBLE. THE 23.00Z GEM IS THE DRIEST OF THE GUIDANCE AND FOCUSES THIS TROUGH FURTHER TO THE SOUTH AND WOULD KEEP THE REGION ON THE DRY SIDE. DESPITE THESE HIGHLY AMPLIFIED SYSTEMS MOVING THROUGH THE UPPER MIDWEST...THE MAIN POOL OF COLD ARCTIC AIR IS CONFINED TO FAR NORTHERN CANADA WITH 850MB TEMPERATURES IN THE 0C TO -10C RANGE ACROSS THE SOUTHERN HALF OF CANADA. THUS...IT DOES NOT LOOK LIKE TEMPERATURES WILL TAKE MUCH OF A DIP AROUND HERE AS THE NORTHERLY FLOW SETS UP TOWARD MID WEEK. && .AVIATION...THROUGH 06Z SUNDAY 1126 PM CST FRI FEB 22 2013 CEILING HEIGHTS ARE THE MAIN CONCERN WITH THIS SET OF TAFS. BUFKIT SOUNDINGS CONTINUE TO SHOW LOW LEVEL MOISTURE IN PLACE...BUT MAYBE A LITTLE OVERDONE BASED ON THE 00Z MPX SOUNDING. VERY LITTLE IN THE WAY OF MVFR CEILINGS NOW BEING SEE ACROSS MINNESOTA. HOWEVER...DO FEEL THAT CEILINGS WILL LOWER LATER TONIGHT BUT NOT AS LOW AS PREVIOUSLY THOUGHT. DOD DID LOWER INTO THE 020K-030K FEET RANGE. WITH THE CYCLONIC FLOW CONTINUING SATURDAY...EXPECT THE MVFR CEILINGS TO RAISE BACK INTO THE VFR CATEGORY AND THEN PERSIST THROUGH 06Z. COULD BE SOME BREAKS IN THE CLOUDS LATE IN THE AFTERNOON AND EVENING...BUT DID KEEP A BROKEN DECK IN THROUGH 06Z. && .ARX WATCHES/WARNINGS/ADVISORIES... 319 AM CST SAT FEB 23 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...HALBACH AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
519 AM CST SAT FEB 23 2013 .AVIATION... MVFR CONDITIONS WILL SLOWLY IMPROVE TO VFR THROUGH 21Z/23 WITH VCNTY SHSN POSSIBLE AT KDBQ AND MAYBE AT KCID/KMLI. AFT 00Z/24 HIGH PRESSURE WILL BUILD INTO THE WESTERN GREAT LAKES. VFR CONDITIONS ARE EXPECTED TO CONTINUE. HOWEVER...LIGHT WINDS AND MAINLY CLEAR SKIES MAY RESULT IN FG DVLPMNT PRIOR TO SUNRISE SUNDAY. ..08.. && .PREV DISCUSSION... /ISSUED 304 AM CST SAT FEB 23 2013/ SYNOPSIS... 06Z SFC ANALYSIS HAS AN OCCLUDED LOW NEARING THE MACKINAC STRAITS WHILE HIGH PRESSURE WAS ACROSS THE PLAINS. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS THE PLAINS WITH 20S AND 30S ACROSS THE GREAT LAKES AND OHIO VALLEY. SHORT TERM...TODAY AND TONIGHT... A COMBINATION OF CYCLONIC FLOW ALOFT AND VORT MAXES...MAINLY AT 700 MB IS PRODUCING FLURRIES/LIGHT SNOW ACROSS THE NORTHERN PART OF THE CWFA AND UP INTO MINNESOTA. THE RAP TRENDS HAVE THE 700MB SHORTWAVE ROTATING THROUGH DURING THE DAY WITH NEAR CONTINUOUS 700MB VORT MAXES ROTATING THROUGH. THUS FLURRIES/VERY LIGHT SNOW WILL BE SEEN ACROSS ROUGHLY THE NORTHERN HALF DURING THE MORNING. FCST SOUNDINGS SHOW A DRYING ALOFT OCCURRING DURING THE AFTERNOON SO ANY FLURRIES/LIGHT SNOW WILL GRADUALLY END. BASED ON 0.5KM CONDENSATION PRESSURES/WIND...CLOUDS SHOULD STAY PUT FOR MUCH OF THE MORNING BEFORE CLEARING STARTS FROM WEST TO EAST DURING THE AFTERNOON. THE COLD POOL ALOFT MAY HELP GENERATE SOME DIURNAL CLOUDS WHICH MAY SLOW THE RATE OF CLEARING DURING THE AFTERNOON HOURS. ..08.. LONG TERM...SUNDAY THROUGH NEXT FRIDAY... THE EXTENDED STORM IS IN MUCH BETTER AGREEMENT IN MODEL FORECASTS TONIGHT...AND IS FOCUSED ON A SURFACE LOW TRACK FROM OK/AR THROUGH INDIANA MONDAY INTO TUESDAY. THE STORM SHOULD ONCE AGAIN HAVE A BROAD UPPER LOW ASSOCIATED WITH IT...AND BY IN LARGE...THE UPPER LOW SHOULD DOMINATE THE AREAL PLACEMENT OF RAIN AND SNOW. THE BIGGEST DIFFERENCE IN MODELS TONIGHT...IS THAT NO MODEL FORECASTS AN INTENSIFYING SURFACE LOW...OR EVEN A STRONG OCCLUDED LOW AS IT MOVES PAST THE REGION. THIS WOULD INDICATE A MUCH LOWER RISK FOR A STRONG WIND DRIVEN SNOW/BLIZZARD THAN THE EARLIER 12Z ECMWF WOULD HAVE INDICATED. DESPITE THIS...THE STORM SHOULD BE ABLE TO PRODUCE A HEALTHY DEFORMATION ZONE...AND ALL MODELS BRUSH THIS FORCING THROUGH THE CENTRAL AND SOUTHERN CWA...AND THIS MAY REQUIRE HEADLINES TO BE ISSUED TODAY IN OUR SOUTH. MODERATE SNOW ACCUMULATIONS OVER 3 INCHES SEEM LIKELY WITH THIS SYSTEM...AND SHOULD A DIRECT HIT FROM THE DEF ZONE OCCUR...HEAVY AMOUNTS ARE POSSIBLE. AS THE SYSTEM MOVES PAST INTO THE LOWER GREAT LAKES...MORE ENERGY IS FORECAST BY THE GFS AND ECMWF TO MOVE INTO THE WESTERN SIDE OF THE UPPER LOW...AND THIS SHOULD PRODUCE AN EXTENDED PERIOD OF LIGHT SNOW BEGINNING TUESDAY NIGHT INTO WEDNESDAY NIGHT. THE GFS IS MOST BULLISH...WITH 1 TO 2 INCHES OF SNOW FOR SEVERAL PERIODS IN A ROW FOR A LARGE AREA...WHILE THE ECMWF IS MORE CONSERVATIVE. ANY WAY YOU SHAKE IT...IT APPEARS UNSETTLED...CLOUDY...WITH LIGHT SNOW OR FLURRIES IN THE WAKE OF THE EARLY WEEK STORM...AT LEAST THROUGH WEDNESDAY NIGHT. LATE WEEK...MODELS SHOW A MUDDLED MESS OF NORTHERLY FLOW ALOFT. THERE CERTAINLY COULD BE SOME SNOW POTENTIAL THERE...BUT IF IT WOULD OCCUR...MOISTURE WOULD BE VERY LIMITED...AND AMOUNTS VERY LIGHT. TEMPERATURES WILL AGAIN BE FORECAST TO AVERAGE BELOW NORMAL ON HIGHS...MAINLY IN THE LOWER TO MID 30S THIS WEEK. LOWS IN THE TEENS TO MID 20S ARE FORECAST FROM NORTHWEST TO SOUTHEAST...WITH THE MILDEST LOWS ASSOCIATED WITH MONDAY NIGHT AND TUESDAY NIGHT AS WE SHOULD EXPERIENCE HIGHER DEWPOINTS WITH THE POTENTIAL SNOW EVENT. ERVIN && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION...CORRECTED
NWS BILLINGS MT
540 AM MST SAT FEB 23 2013 .SHORT TERM...VALID FOR TDY AND SUN... WE UPDATED THE FORECAST TO CANCEL THE WIND ADVISORY FOR LIVINGSTON AND NYE SINCE OBSERVATIONS HAVE WINDS WELL BELOW CRITERIA NOW. THE SURFACE PRESSURES ARE FALLING ACROSS YELLOWSTONE PARK AS THE LEFT EXIT REGION OF THE 300-HPA JET STREAK APPROACHES...SO THE GRADIENT IS NO LONGER TIGHT ENOUGH TO SUPPORT STRONG GAP WINDS. SCHULTZ PREVIOUS DISCUSSION...ISSUED AT 308 AM MST SAT FEB 23 2013... PASSAGE OF A 500-HPA SHORT WAVE TROUGH AND SURFACE COLD FRONT WILL BRING SNOW SHOWER CHANCES TO THE FOREFRONT TODAY. MOISTURE CHANNEL IMAGERY AT 10 UTC SHOWS THAT TROUGH AXIS ENTERING WESTERN ID...AND THAT IS STARTING TO DISRUPT THE ENVIRONMENT NEEDED FOR NOTABLE GAP WINDS. THAT PROCESS SHOULD BE COMPLETE BETWEEN 12 AND 15 UTC...BUT IN THE INTERIM WE WILL LET OUR WIND ADVISORY AT LIVINGSTON AND NYE RIDE FOR A FEW MORE HOURS. TODAY AND TONIGHT...WE HAVE POPS IN THE 60 TO 90 PERCENT RANGE FOR 1/ THE LIVINGSTON...BIG TIMBER...AND COOKE CITY AREAS UNTIL 18 UTC AND 2/ THE LODGE GRASS...SHERIDAN...AND EVEN BROADUS AREAS BETWEEN 18 AND 06 UTC. THOSE LIKELY AND CATEGORICAL POPS ARE LINED UP WITH THE MOST GENEROUS SYNOPTIC-SCALE FORCING WITH THE SHORT WAVE ALOFT AND THE EXIT REGION OF A WEAKENING 300-HPA JET STREAK WHICH THE 00 UTC GUIDANCE SHOWS SINKING SOUTHWARD TODAY. WE HAVE CHANCE POPS IN MOST OTHER PLACES DURING THE DAY...INCLUDING BILLINGS...BUT DIDN/T GO ANY HIGHER IN ORDER TO CONVEY THE MORE SCATTERED OR SHORT-LIVED NATURE OF SHOWERS OUTSIDE OF THE BETTER FORCING. SNOW IS MENTIONED AS THE PREDOMINATE PRECIPITATION TYPE FOR MOST OF THE AREA BECAUSE THAT NOTION HAS STRONG SUPPORT FROM GFS/ECMWF/NAM WET BULB HEIGHTS AND NCEP PRECIPITATION-TYPE ALGORITHMS APPLIED TO THE 21 UTC SREF. WHERE IMPACTS ARE CONCERNED...OUR MAIN CONCERN IS FOR SHERIDAN AND MAYBE EVEN SOUTHERN BIG HORN COUNTY...WHERE THERE IS SOME RISK OF ADVISORY-LEVEL SNOWFALL THIS AFTERNOON AND EVENING. THE 00 UTC GFS AND RECENT RUNS OF THE RAP /WHICH GETS LATERAL BOUNDARY CONDITIONS FROM THE GFS/ ARE THE MOST AGGRESSIVE QPF SOLUTIONS FOR THAT AREA. HOWEVER...SINCE THOSE QPF NUMBERS ARE HIGHER THAN MOST OF THE REST OF THE PACK...AND BECAUSE IT IS NOT CLEAR HOW EFFICIENT UPSLOPE IN THE LOW LEVELS WILL BE...WE CHOSE TO KEEP SNOW AMOUNTS IN THE 1 TO 3 INCH RANGE /JUST BELOW ADVISORY CRITERIA/ FOR NOW. THIS COULD BE A CASE WHERE NEAR TERM OBSERVATIONAL TRENDS GIVE ENOUGH CONFIDENCE FOR US TO HOIST A HEADLINE LATER TODAY IF GFS-BASED SOLUTIONS WIND UP BEING CORRECT. THE 06 UTC GFS HAS TRENDED EVEN HIGHER WITH ITS QPF...SO THIS SITUATION BEARS CLOSE WATCHING. SUN...NORTH-NORTHWEST FLOW WILL BE IN PLACE ALOFT WITH BOTH MODEST DRYING AND WARMING IN THE LOW- AND MID-LEVELS. WE DECIDED TO LEAVE OUR GOING FORECAST ALONE FOR NOW SINCE IT SHOWS POPS MAINLY BEFORE 18 UTC...WHEN FLOW IS MORE CYCLONIC. HOWEVER...BOTH THE 00 UTC GFS AND NAM SHOW A DECENT BATCH OF 500-300 HPA Q-VECTOR CONVERGENCE IN THE 18 TO 00 UTC TIME FRAME...WHICH MAKES US WONDER IF THERE COULD BE SOME CONVECTION DURING THE AFTERNOON. THAT WILL BE SOMETHING TO CONSIDER WITH LATER FORECAST RELEASES. OTHERWISE...WE DID INCREASE HIGHS USING THE 00 UTC BIAS-CORRECTED MULTI-MODEL CONSENSUS /WHICH HAS VERIFIED WELL LATELY/...AND WINDS ON SUN NIGHT NEAR LIVINGSTON AND BIG TIMBER AS SURFACE PRESSURE FALLS BEGIN ACROSS THE NORTHERN ROCKIES AGAIN. SCHULTZ .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MODELS IN PRETTY GOOD AGREEMENT THROUGH WEDNESDAY. SMALL SYSTEM FOR THURSDAY SHOWS SOME SIGNS OF GETTING BETTER ORGANIZED IN THE GFS BUT NOT SO MUCH IN THE EUROPEAN MODEL. STRONG RIDGING AND MUCH WARMER TEMPERATURES LOOK TO BE ON TRACK FOR NEXT WEEKEND. BRIEF RIDGING BEHIND SUNDAY SYSTEM SHOULD BRING PARTLY CLOUDY AND DRY CONDITIONS TO THE FIRST HALF OF MONDAY. BY LATE IN THE DAY NEXT SYSTEM UPSTREAM QUICKLY BUILDS INTO THE AREA WITH INCREASING PRECIPITATION CHANCES THROUGH TUESDAY. SOME WEAK ENERGY LINGERS INTO WEDNESDAY OVER SOUTHERN ZONES BUT BY WEDNESDAY AFTERNOON RIDGING DEVELOPS ENDING PRECIPITATION CHANCES. GFS BRINGS NEXT SYSTEM INTO IDAHO WEDNESDAY NIGHT AND SEEMS TO BE TRYING TO CUT OFF UPPER LOW NEAR WEST YELLOWSTONE THURSDAY MORNING. ECMWF DIGS THIS SAME TROF MUCH FURTHER SOUTH AND SPLITS THE SYSTEM OVER THE AREA RESULTING IN SOME CLOUD COVER BUT LITTLE IN THE WAY OF PRECIPITATION OUTSIDE OF MOUNTAIN AREAS. CAUSE OF THE DIFFERENCES IS DUE TO HANDLING OF STRONG DOWNSTREAM SYSTEM OVER THE EASTERN US...AND CURRENT GUIDANCE FAVORS THE EC SOLUTION SO LEFT FORECAST DRY AND WARMED TEMPERATURES JUST A BIT. ALL THE MODELS IN GOOD AGREEMENT WITH DEVELOPMENT OF STRONG RIDGING FRIDAY THROUGH NEXT WEEKEND. BOTH MODELS SHOW SATURDAY 850 TEMPERATURES IN THE +6 TO +10C RANGE LEADING TO MIX DOWN TEMPERATURES WELL INTO THE 50S FOR HIGHS FRIDAY THROUGH SUNDAY. NOT OUT OF THE QUESTION TO SEE SOME LOWER 60S SATURDAY AND SUNDAY WITH DRY CONDITIONS UNDER THE RIDGE. CHAMBERS && .AVIATION... GUSTY SOUTHWEST WINDS IN THE KLVM VICINITY WILL DECREASE THIS MORNING BEHIND COLD FRONT. SCATTERED SNOW SHOWERS WILL DEVELOP FROM WEST TO EAST ACROSS THE AREA TODAY AS THE COLD FRONT MOVES THROUGH. VFR CONDITIONS WILL PREVAIL IN MOST AREAS WITH LOCAL MVFR CONDITIONS NEAR SNOW SHOWERS. FOOTHILLS AND MOUNTAIN AREAS WILL SEE MAINLY MVFR CONDITIONS WITH LOCAL IFR OR LOWER CONDITIONS WITH HEAVIER SNOW SHOWERS EXPECTED IN THESE AREAS. MOUNTAIN AND PASS OBSCURATION WILL EXIST FOR ALL AREA MOUNTAINS THROUGH TONIGHT. CHAMBERS && .PRELIMINARY POINT TEMP/POPS... TDY SUN MON TUE WED THU FRI ------------------------------------------------------- BIL 041 025/041 022/039 024/037 021/037 023/045 026/051 4/J 32/J 11/B 33/J 11/U 32/J 00/B LVM 039 020/035 016/035 019/032 013/033 017/038 025/044 7/J 33/W 12/J 44/J 11/U 32/J 11/B HDN 042 023/043 019/037 022/036 017/035 020/043 023/049 5/W 43/J 11/B 34/J 21/U 33/J 10/B MLS 044 027/042 021/037 022/036 020/035 020/041 024/047 2/W 22/J 11/U 23/J 21/B 12/J 10/B 4BQ 041 024/038 017/035 020/033 018/032 017/039 020/045 6/W 73/J 11/U 24/J 21/B 12/J 10/B BHK 041 024/035 016/032 019/031 018/031 016/036 018/040 3/J 22/J 11/U 13/J 21/B 11/B 10/B SHR 038 020/036 012/034 018/032 015/033 016/039 018/045 7/J 83/J 11/U 44/J 21/U 22/J 10/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
524 AM MST SAT FEB 23 2013 .SHORT TERM...VALID FOR TDY AND SUN... WE UPDATED THE FORECAST TO CANCEL THE WIND ADVISORY FOR LIVINGSTON AND NYE SINCE OBSERVATIONS HAVE WINDS WELL BELOW CRITERIA NOW. THE SURFACE PRESSURES ARE FALLING ACROSS YELLOWSTONE PARK AS THE RIGHT EXIT REGION OF THE 300-HPA JET STREAK APPROACHES...SO THE GRADIENT IS NO LONGER TIGHT ENOUGH TO SUPPORT STRONG GAP WINDS. SCHULTZ PREVIOUS DISCUSSION...ISSUED AT 308 AM MST SAT FEB 23 2013... PASSAGE OF A 500-HPA SHORT WAVE TROUGH AND SURFACE COLD FRONT WILL BRING SNOW SHOWER CHANCES TO THE FOREFRONT TODAY. MOISTURE CHANNEL IMAGERY AT 10 UTC SHOWS THAT TROUGH AXIS ENTERING WESTERN ID...AND THAT IS STARTING TO DISRUPT THE ENVIRONMENT NEEDED FOR NOTABLE GAP WINDS. THAT PROCESS SHOULD BE COMPLETE BETWEEN 12 AND 15 UTC...BUT IN THE INTERIM WE WILL LET OUR WIND ADVISORY AT LIVINGSTON AND NYE RIDE FOR A FEW MORE HOURS. TODAY AND TONIGHT...WE HAVE POPS IN THE 60 TO 90 PERCENT RANGE FOR 1/ THE LIVINGSTON...BIG TIMBER...AND COOKE CITY AREAS UNTIL 18 UTC AND 2/ THE LODGE GRASS...SHERIDAN...AND EVEN BROADUS AREAS BETWEEN 18 AND 06 UTC. THOSE LIKELY AND CATEGORICAL POPS ARE LINED UP WITH THE MOST GENEROUS SYNOPTIC-SCALE FORCING WITH THE SHORT WAVE ALOFT AND THE EXIT REGION OF A WEAKENING 300-HPA JET STREAK WHICH THE 00 UTC GUIDANCE SHOWS SINKING SOUTHWARD TODAY. WE HAVE CHANCE POPS IN MOST OTHER PLACES DURING THE DAY...INCLUDING BILLINGS...BUT DIDN/T GO ANY HIGHER IN ORDER TO CONVEY THE MORE SCATTERED OR SHORT-LIVED NATURE OF SHOWERS OUTSIDE OF THE BETTER FORCING. SNOW IS MENTIONED AS THE PREDOMINATE PRECIPITATION TYPE FOR MOST OF THE AREA BECAUSE THAT NOTION HAS STRONG SUPPORT FROM GFS/ECMWF/NAM WET BULB HEIGHTS AND NCEP PRECIPITATION-TYPE ALGORITHMS APPLIED TO THE 21 UTC SREF. WHERE IMPACTS ARE CONCERNED...OUR MAIN CONCERN IS FOR SHERIDAN AND MAYBE EVEN SOUTHERN BIG HORN COUNTY...WHERE THERE IS SOME RISK OF ADVISORY-LEVEL SNOWFALL THIS AFTERNOON AND EVENING. THE 00 UTC GFS AND RECENT RUNS OF THE RAP /WHICH GETS LATERAL BOUNDARY CONDITIONS FROM THE GFS/ ARE THE MOST AGGRESSIVE QPF SOLUTIONS FOR THAT AREA. HOWEVER...SINCE THOSE QPF NUMBERS ARE HIGHER THAN MOST OF THE REST OF THE PACK...AND BECAUSE IT IS NOT CLEAR HOW EFFICIENT UPSLOPE IN THE LOW LEVELS WILL BE...WE CHOSE TO KEEP SNOW AMOUNTS IN THE 1 TO 3 INCH RANGE /JUST BELOW ADVISORY CRITERIA/ FOR NOW. THIS COULD BE A CASE WHERE NEAR TERM OBSERVATIONAL TRENDS GIVE ENOUGH CONFIDENCE FOR US TO HOIST A HEADLINE LATER TODAY IF GFS-BASED SOLUTIONS WIND UP BEING CORRECT. THE 06 UTC GFS HAS TRENDED EVEN HIGHER WITH ITS QPF...SO THIS SITUATION BEARS CLOSE WATCHING. SUN...NORTH-NORTHWEST FLOW WILL BE IN PLACE ALOFT WITH BOTH MODEST DRYING AND WARMING IN THE LOW- AND MID-LEVELS. WE DECIDED TO LEAVE OUR GOING FORECAST ALONE FOR NOW SINCE IT SHOWS POPS MAINLY BEFORE 18 UTC...WHEN FLOW IS MORE CYCLONIC. HOWEVER...BOTH THE 00 UTC GFS AND NAM SHOW A DECENT BATCH OF 500-300 HPA Q-VECTOR CONVERGENCE IN THE 18 TO 00 UTC TIME FRAME...WHICH MAKES US WONDER IF THERE COULD BE SOME CONVECTION DURING THE AFTERNOON. THAT WILL BE SOMETHING TO CONSIDER WITH LATER FORECAST RELEASES. OTHERWISE...WE DID INCREASE HIGHS USING THE 00 UTC BIAS-CORRECTED MULTI-MODEL CONSENSUS /WHICH HAS VERIFIED WELL LATELY/...AND WINDS ON SUN NIGHT NEAR LIVINGSTON AND BIG TIMBER AS SURFACE PRESSURE FALLS BEGIN ACROSS THE NORTHERN ROCKIES AGAIN. SCHULTZ .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MODELS IN PRETTY GOOD AGREEMENT THROUGH WEDNESDAY. SMALL SYSTEM FOR THURSDAY SHOWS SOME SIGNS OF GETTING BETTER ORGANIZED IN THE GFS BUT NOT SO MUCH IN THE EUROPEAN MODEL. STRONG RIDGING AND MUCH WARMER TEMPERATURES LOOK TO BE ON TRACK FOR NEXT WEEKEND. BRIEF RIDGING BEHIND SUNDAY SYSTEM SHOULD BRING PARTLY CLOUDY AND DRY CONDITIONS TO THE FIRST HALF OF MONDAY. BY LATE IN THE DAY NEXT SYSTEM UPSTREAM QUICKLY BUILDS INTO THE AREA WITH INCREASING PRECIPITATION CHANCES THROUGH TUESDAY. SOME WEAK ENERGY LINGERS INTO WEDNESDAY OVER SOUTHERN ZONES BUT BY WEDNESDAY AFTERNOON RIDGING DEVELOPS ENDING PRECIPITATION CHANCES. GFS BRINGS NEXT SYSTEM INTO IDAHO WEDNESDAY NIGHT AND SEEMS TO BE TRYING TO CUT OFF UPPER LOW NEAR WEST YELLOWSTONE THURSDAY MORNING. ECMWF DIGS THIS SAME TROF MUCH FURTHER SOUTH AND SPLITS THE SYSTEM OVER THE AREA RESULTING IN SOME CLOUD COVER BUT LITTLE IN THE WAY OF PRECIPITATION OUTSIDE OF MOUNTAIN AREAS. CAUSE OF THE DIFFERENCES IS DUE TO HANDLING OF STRONG DOWNSTREAM SYSTEM OVER THE EASTERN US...AND CURRENT GUIDANCE FAVORS THE EC SOLUTION SO LEFT FORECAST DRY AND WARMED TEMPERATURES JUST A BIT. ALL THE MODELS IN GOOD AGREEMENT WITH DEVELOPMENT OF STRONG RIDGING FRIDAY THROUGH NEXT WEEKEND. BOTH MODELS SHOW SATURDAY 850 TEMPERATURES IN THE +6 TO +10C RANGE LEADING TO MIX DOWN TEMPERATURES WELL INTO THE 50S FOR HIGHS FRIDAY THROUGH SUNDAY. NOT OUT OF THE QUESTION TO SEE SOME LOWER 60S SATURDAY AND SUNDAY WITH DRY CONDITIONS UNDER THE RIDGE. CHAMBERS && .AVIATION... GUSTY SOUTHWEST WINDS IN THE KLVM VICINITY WILL DECREASE THIS MORNING BEHIND COLD FRONT. SCATTERED SNOW SHOWERS WILL DEVELOP FROM WEST TO EAST ACROSS THE AREA TODAY AS THE COLD FRONT MOVES THROUGH. VFR CONDITIONS WILL PREVAIL IN MOST AREAS WITH LOCAL MVFR CONDITIONS NEAR SNOW SHOWERS. FOOTHILLS AND MOUNTAIN AREAS WILL SEE MAINLY MVFR CONDITIONS WITH LOCAL IFR OR LOWER CONDITIONS WITH HEAVIER SNOW SHOWERS EXPECTED IN THESE AREAS. MOUNTAIN AND PASS OBSCURATION WILL EXIST FOR ALL AREA MOUNTAINS THROUGH TONIGHT. CHAMBERS && .PRELIMINARY POINT TEMP/POPS... TDY SUN MON TUE WED THU FRI ------------------------------------------------------- BIL 041 025/041 022/039 024/037 021/037 023/045 026/051 4/J 32/J 11/B 33/J 11/U 32/J 00/B LVM 039 020/035 016/035 019/032 013/033 017/038 025/044 7/J 33/W 12/J 44/J 11/U 32/J 11/B HDN 042 023/043 019/037 022/036 017/035 020/043 023/049 5/W 43/J 11/B 34/J 21/U 33/J 10/B MLS 044 027/042 021/037 022/036 020/035 020/041 024/047 2/W 22/J 11/U 23/J 21/B 12/J 10/B 4BQ 041 024/038 017/035 020/033 018/032 017/039 020/045 6/W 73/J 11/U 24/J 21/B 12/J 10/B BHK 041 024/035 016/032 019/031 018/031 016/036 018/040 3/J 22/J 11/U 13/J 21/B 11/B 10/B SHR 038 020/036 012/034 018/032 015/033 016/039 018/045 7/J 83/J 11/U 44/J 21/U 22/J 10/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
308 AM MST SAT FEB 23 2013 .SHORT TERM...VALID FOR TDY AND SUN... PASSAGE OF A 500-HPA SHORT WAVE TROUGH AND SURFACE COLD FRONT WILL BRING SNOW SHOWER CHANCES TO THE FOREFRONT TODAY. MOISTURE CHANNEL IMAGERY AT 10 UTC SHOWS THAT TROUGH AXIS ENTERING WESTERN ID...AND THAT IS STARTING TO DISRUPT THE ENVIRONMENT NEEDED FOR NOTABLE GAP WINDS. THAT PROCESS SHOULD BE COMPLETE BETWEEN 12 AND 15 UTC...BUT IN THE INTERIM WE WILL LET OUR WIND ADVISORY AT LIVINGSTON AND NYE RIDE FOR A FEW MORE HOURS. TODAY AND TONIGHT...WE HAVE POPS IN THE 60 TO 90 PERCENT RANGE FOR 1/ THE LIVINGSTON...BIG TIMBER...AND COOKE CITY AREAS UNTIL 18 UTC AND 2/ THE LODGE GRASS...SHERIDAN...AND EVEN BROADUS AREAS BETWEEN 18 AND 06 UTC. THOSE LIKELY AND CATEGORICAL POPS ARE LINED UP WITH THE MOST GENEROUS SYNOPTIC-SCALE FORCING WITH THE SHORT WAVE ALOFT AND THE EXIT REGION OF A WEAKENING 300-HPA JET STREAK WHICH THE 00 UTC GUIDANCE SHOWS SINKING SOUTHWARD TODAY. WE HAVE CHANCE POPS IN MOST OTHER PLACES DURING THE DAY...INCLUDING BILLINGS...BUT DIDN/T GO ANY HIGHER IN ORDER TO CONVEY THE MORE SCATTERED OR SHORT-LIVED NATURE OF SHOWERS OUTSIDE OF THE BETTER FORCING. SNOW IS MENTIONED AS THE PREDOMINATE PRECIPITATION TYPE FOR MOST OF THE AREA BECAUSE THAT NOTION HAS STRONG SUPPORT FROM GFS/ECMWF/NAM WET BULB HEIGHTS AND NCEP PRECIPITATION-TYPE ALGORITHMS APPLIED TO THE 21 UTC SREF. WHERE IMPACTS ARE CONCERNED...OUR MAIN CONCERN IS FOR SHERIDAN AND MAYBE EVEN SOUTHERN BIG HORN COUNTY...WHERE THERE IS SOME RISK OF ADVISORY-LEVEL SNOWFALL THIS AFTERNOON AND EVENING. THE 00 UTC GFS AND RECENT RUNS OF THE RAP /WHICH GETS LATERAL BOUNDARY CONDITIONS FROM THE GFS/ ARE THE MOST AGGRESSIVE QPF SOLUTIONS FOR THAT AREA. HOWEVER...SINCE THOSE QPF NUMBERS ARE HIGHER THAN MOST OF THE REST OF THE PACK...AND BECAUSE IT IS NOT CLEAR HOW EFFICIENT UPSLOPE IN THE LOW LEVELS WILL BE...WE CHOSE TO KEEP SNOW AMOUNTS IN THE 1 TO 3 INCH RANGE /JUST BELOW ADVISORY CRITERIA/ FOR NOW. THIS COULD BE A CASE WHERE NEAR TERM OBSERVATIONAL TRENDS GIVE ENOUGH CONFIDENCE FOR US TO HOIST A HEADLINE LATER TODAY IF GFS-BASED SOLUTIONS WIND UP BEING CORRECT. THE 06 UTC GFS HAS TRENDED EVEN HIGHER WITH ITS QPF...SO THIS SITUATION BEARS CLOSE WATCHING. SUN...NORTH-NORTHWEST FLOW WILL BE IN PLACE ALOFT WITH BOTH MODEST DRYING AND WARMING IN THE LOW- AND MID-LEVELS. WE DECIDED TO LEAVE OUR GOING FORECAST ALONE FOR NOW SINCE IT SHOWS POPS MAINLY BEFORE 18 UTC...WHEN FLOW IS MORE CYCLONIC. HOWEVER...BOTH THE 00 UTC GFS AND NAM SHOW A DECENT BATCH OF 500-300 HPA Q-VECTOR CONVERGENCE IN THE 18 TO 00 UTC TIME FRAME...WHICH MAKES US WONDER IF THERE COULD BE SOME CONVECTION DURING THE AFTERNOON. THAT WILL BE SOMETHING TO CONSIDER WITH LATER FORECAST RELEASES. OTHERWISE...WE DID INCREASE HIGHS USING THE 00 UTC BIAS-CORRECTED MULTI-MODEL CONSENSUS /WHICH HAS VERIFIED WELL LATELY/...AND WINDS ON SUN NIGHT NEAR LIVINGSTON AND BIG TIMER AS SURFACE PRESSURE FALLS BEGIN ACROSS THE NORTHERN ROCKIES AGAIN. SCHULTZ .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MODELS IN PRETTY GOOD AGREEMENT THROUGH WEDNESDAY. SMALL SYSTEM FOR THURSDAY SHOWS SOME SIGNS OF GETTING BETTER ORGANIZED IN THE GFS BUT NOT SO MUCH IN THE EUROPEAN MODEL. STRONG RIDGING AND MUCH WARMER TEMPERATURES LOOK TO BE ON TRACK FOR NEXT WEEKEND. BRIEF RIDGING BEHIND SUNDAY SYSTEM SHOULD BRING PARTLY CLOUDY AND DRY CONDITIONS TO THE FIRST HALF OF MONDAY. BY LATE IN THE DAY NEXT SYSTEM UPSTREAM QUICKLY BUILDS INTO THE AREA WITH INCREASING PRECIPITATION CHANCES THROUGH TUESDAY. SOME WEAK ENERGY LINGERS INTO WEDNESDAY OVER SOUTHERN ZONES BUT BY WEDNESDAY AFTERNOON RIDGING DEVELOPS ENDING PRECIPITATION CHANCES. GFS BRINGS NEXT SYSTEM INTO IDAHO WEDNESDAY NIGHT AND SEEMS TO BE TRYING TO CUT OFF UPPER LOW NEAR WEST YELLOWSTONE THURSDAY MORNING. ECMWF DIGS THIS SAME TROF MUCH FURTHER SOUTH AND SPLITS THE SYSTEM OVER THE AREA RESULTING IN SOME CLOUD COVER BUT LITTLE IN THE WAY OF PRECIPITATION OUTSIDE OF MOUNTAIN AREAS. CAUSE OF THE DIFFERENCES IS DUE TO HANDLING OF STRONG DOWNSTREAM SYSTEM OVER THE EASTERN US...AND CURRENT GUIDANCE FAVORS THE EC SOLUTION SO LEFT FORECAST DRY AND WARMED TEMPERATURES JUST A BIT. ALL THE MODELS IN GOOD AGREEMENT WITH DEVELOPMENT OF STRONG RIDGING FRIDAY THROUGH NEXT WEEKEND. BOTH MODELS SHOW SATURDAY 850 TEMPERATURES IN THE +6 TO +10C RANGE LEADING TO MIX DOWN TEMPERATURES WELL INTO THE 50S FOR HIGHS FRIDAY THROUGH SUNDAY. NOT OUT OF THE QUESTION TO SEE SOME LOWER 60S SATURDAY AND SUNDAY WITH DRY CONDITIONS UNDER THE RIDGE. CHAMBERS && .AVIATION... GUSTY SOUTHWEST WINDS IN THE KLVM VICINITY WILL DECREASE THIS MORNING BEHIND COLD FRONT. SCATTERED SNOW SHOWERS WILL DEVELOP FROM WEST TO EAST ACROSS THE AREA TODAY AS THE COLD FRONT MOVES THROUGH. VFR CONDITIONS WILL PREVAIL IN MOST AREAS WITH LOCAL MVFR CONDITIONS NEAR SNOW SHOWERS. FOOTHILLS AND MOUNTAIN AREAS WILL SEE MAINLY MVFR CONDITIONS WITH LOCAL IFR OR LOWER CONDITIONS WITH HEAVIER SNOW SHOWERS EXPECTED IN THESE AREAS. MOUNTAIN AND PASS OBSCURATION WILL EXIST FOR ALL AREA MOUNTAINS THROUGH TONIGHT. CHAMBERS && .PRELIMINARY POINT TEMP/POPS... TDY SUN MON TUE WED THU FRI ------------------------------------------------------- BIL 041 025/041 022/039 024/037 021/037 023/045 026/051 4/J 32/J 11/B 33/J 11/U 32/J 00/B LVM 039 020/035 016/035 019/032 013/033 017/038 025/044 7/J 33/W 12/J 44/J 11/U 32/J 11/B HDN 042 023/043 019/037 022/036 017/035 020/043 023/049 5/W 43/J 11/B 34/J 21/U 33/J 10/B MLS 044 027/042 021/037 022/036 020/035 020/041 024/047 2/W 22/J 11/U 23/J 21/B 12/J 10/B 4BQ 041 024/038 017/035 020/033 018/032 017/039 020/045 6/W 73/J 11/U 24/J 21/B 12/J 10/B BHK 041 024/035 016/032 019/031 018/031 016/036 018/040 3/J 22/J 11/U 13/J 21/B 11/B 10/B SHR 038 020/036 012/034 018/032 015/033 016/039 018/045 7/J 83/J 11/U 44/J 21/U 22/J 10/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WIND ADVISORY IN EFFECT UNTIL 10 AM MST THIS MORNING FOR ZONES 65-66. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
954 AM EST SAT FEB 23 2013 .SYNOPSIS... A COMBINATION OF TWO STORM SYSTEMS...ONE TO OUR NORTHWEST AND ANOTHER MOVING UP THE COAST...WILL BRING US UNSETTLED WEATHER TODAY WITH PLENTY OF CLOUDS. MOST OF THE AREA WILL SEE RAIN DEVELOP BY AFTERNOON...BUT SOME WET SNOW IS POSSIBLE ACROSS ONEIDA COUNTY AND THE CATSKILLS. BY TONIGHT AS COLDER AIR MOVES BACK INTO OUR AREA...A PERIOD OF FREEZING RAIN IS POSSIBLE OVER THE CATSKILLS...WITH A GRADUAL TRANSITION FROM RAIN TO SNOW OVER THE ENTIRE AREA BEFORE ENDING. LIGHT SNOW SHOWERS ARE POSSIBLE SUNDAY IN CENTRAL NY WITH DRIER WEATHER BY MONDAY. && .NEAR TERM /THROUGH TONIGHT/... 930 AM UPDATE... CONVOLUTED FCST WITH CWA RMNG IN VRY WK FORCING AND PCPN POPPING UP AT RANDOM ACRS THE AREA, THO MOST IS CONFINED CLOSER TO H5-H7 LIFT IN THE FINGER LKS REGION. 12Z RAOBS FM KBUF AND KALY SHOWING VRY LITTLE ICE IN THE CLD, IN AGREEMENT WITH FCST SNDGS FM BUFKIT. MOST OBS ACRS THE AREA ARE REPORTING SOME FORM OF LIQUID THUS HV TWEAKED WX GRIDS TO GO RAIN OR DRIZZLE EXCEPT WHERE LOCALES ARE BLO FZG AND HV ADDED IN A FRZG MENTION. MOISTURE RETURNS IN THE -10C TO -20C LAYER AFTR ABOUT 18Z THIS AFTN AND HV ADDED IN SNOW/FLURRY MENTION BACK IN. BEST CHC FOR SNOW LOOKS TO BE ACRS NRN ONEIDA CNTY LATE THIS AFTN WITH STRONG CONVERGENCE BRINGING A QUICK 1-2 INCHES LATE TDA. ELSEWHERE IT LOOKS TO BE A WINTRY MESS FOR MOST OF THE DAY. LATEST NAM12 HAS COME IN WITH CURRENT SFC LOW LOCATED OFF OF VA/NC BORDER RMNG SOUTH OF OUR AREA TONIGHT AND VRY MINIMAL QPF SPREADING INTO SERN PARTS OF CWA THRU TONIGHT. ONSHORE FLOW WL BE POSSIBLE WITH CHC CONTG FOR LGT PCPN BUT WL IT BE IN THE FORM OF LGT FZRA OR FZDZ. WL AWAIT ADDNL 12Z GUIDANCE BFR MAKING DECISION ON WHAT TO DO WITH EXISTING ADVISORY FOR TONIGHT, WHETHER IT BE TO TWEAK THE AREA OR CANCEL IT ALTOGETHER. ONLY MINOR TWEAKS MADE TO HRLY T/TD GRIDS AT THIS TIME. 6 AM UPDATE... THIS MORNING...AN AREA OF PRECIPITATION MAINLY FROM THE NY/PA LINE NORTH THROUGH THE FINGER LAKES CONTINUES TO MOVE THROUGH OUR AREA. OVER THE PAST 2 HOURS THE INTENSITY ON RADAR OF THIS PRECIP HAS INCREASED. THIS IS LIKELY DUE TO SOME SLEET MIXING IN AS EVIDENT BY LOWER VALUES OF CC ON THE DUAL POL PRODUCTS. THIS IS INDICATING MIXED HYDROMETEORS AND BASED ON SOUNDINGS AND THIS AREA COINCIDING WITH HIGHER RETURNS...SLEET IS THE MOST LIKELY P-TYPE HERE. THE LATEST RUC SEEMS TO OFFER THE BEST HOPE FOR A SHORT TERM FORECAST BASED ON A LOBE OF VORTICITY AT 500 MB MOVING THROUGH...THAT LINES UP WELL WITH THE PRECIP. THE RUC MOVES THIS OFF TO THE NORTHEAST BY 12Z. BASED ON RADAR TRENDS THOUGH MAY SLOW THIS DOWN A TAD. PRECIP INTENSITY WILL BE RELATIVELY LIGHT AS WILL QPF AMOUNTS. WE ARE LACKING ICE IN THE CLOUD SO P-TYPE LOOKS TO BE MAINLY RAIN OR SOME ICE PELLETS EXCEPT ACROSS THE FAR NORTH AND EAST WHERE SLIGHTLY DEEPER MOISTURE PROFILES ALLOW FOR SOME SNOW. ISOLATED POCKETS OF FREEZING RAIN ARE POSSIBLE BUT IT APPEARS WHERE THE LIQUID PRECIP IS MOST LIKELY...TEMPS ARE ALREADY NEAR OR ABOVE FREEZING. WHERE WE HAVE COLDER SURFACE TEMPS...MOISTURE ALOFT SUPPORTS MORE SNOW. AFTER THIS MOVES THROUGH WE MAY SEE A LULL FOR A FEW HOURS FOR MOST OF US. LATER THIS MORNING/TONIGHT...NEXT FEATURES OF INTEREST WILL BE AN AREA OF LOW PRESSURE MOVING THROUGH THE GREAT LAKES AND AN AREA OF LOW PRESSURE NOW TAKING SHAPE OFF THE CAROLINA COAST. OUR AREA WILL BE IN ON THE SQUEEZE PLAY TODAY WITH INCREASING MOISTURE FROM BOTH THE WEST (GREAT LAKES SYSTEM) AND EAST (COASTAL SYSTEM). MAIN ADJUSTMENT WAS TO TRIM BACK POPS IN THE MIDDLE TODAY...AND PUSH BACK THE BEST SHOT AT WIDESPREAD PRECIPITATION INTO THE 18Z - 22Z RANGE. OVERALL THOUGH LOOKING AT A FAIRLY LIGHT QPF EVENT WITH AROUND AMOUNTS RANGING FROM A TENTH TO TWO TENTHS. THE FIRST TRIGGER FOR PRECIP WILL COME BY LATE MORNING AS A RIBBON OF PVA SLIDES INTO WESTERN NY...IN THE FLOW AROUND THE PARENT UPPER LOW OVER THE GREAT LAKES. THIS WILL MOVE ACROSS THE REST OF THE AREA TOWARD 20Z...AS WE ALSO GETTING INCREASING UPPER LEVEL LIFT OVER THE FAR SOUTHEAST IN RESPONSE TO THE COASTAL LOW. I RAMP POPS UP GREATLY IN THE 22Z TO 0Z PERIOD TO SHOW OUR BEST SHOT AT PRECIPITATION ACROSS MOST OF THE AREA AS THIS HAPPENS. AS FAR AS P-TYPE GOES...A TONGUE OF WARMER AIR AROUND 800 MB WILL KEEP US MOSTLY RAIN THROUGH LATE THIS AFTERNOON. THE EXCEPTION WILL BE ACROSS NORTHERN ONEIDA COUNTY WHERE TEMPS ALOFT NEVER GET ABOVE 0C...SO AT THE VERY LEAST A RAIN/SNOW MIX IS LIKELY IF NOT MOSTLY SNOW...ALL DAY. WE COULD SEE UP TO 2 INCHES HERE THROUGH AFTERNOON ACROSS THE HIGHER TERRAIN. OVER THE FAR EAST SNOW IS POSSIBLE EARLY BUT EVEN HERE TEMPS ALOFT WARM UP ABOVE 0C AFTER 21Z. DURING THIS TIME SOME AREAS OF FREEZING RAIN ARE POSSIBLE IN OUR NORMALLY COLDEST SECTIONS...WITH PLAIN RAIN OR A FEW SLEET PELLETS POSSIBLE ELSEWHERE. TONIGHT...AS THE COASTAL SYSTEM DEEPENS AND MOVES WELL OUT TO SEA...COLDER AIR ALOFT WILL RAPIDLY MOVE IN FROM THE WEST. THIS WILL CHANGE OUR RAIN OVER TO A PERIOD OF LIGHT SNOW BEFORE ENDING OVERNIGHT. ACCUMS EXPECTED TO BE AROUND AN INCH OR LESS. THE TRICKY SPOT WILL BE ROUGHLY FROM DELAWARE COUNTY SOUTH THROUGH WAYNE AND PIKE COUNTIES...WHERE TEMPS ALOFT WILL REMAIN ABOVE 0C THROUGH 03Z THIS EVENING. NAM SOUNDINGS HAVE REMAINED CONSISTENT SINCE LAST NIGHT SHOWING SOME BOUNDARY LAYER COOLING DURING THIS TIME ALLOWING SURFACE TEMPS TO BE NEAR OR SLIGHTLY BELOW FREEZING. GFS PROFILES COULD NOT BE MORE DIFFERENT WITH TEMPS REMAINING ABOVE FREEZING AT THE SURFACE...BEFORE A RAPID TRANSITION FROM RAIN TO SNOW...WITH NO PERIOD OF FREEZING RAIN. SREF PROFILES PROVIDE LITTLE HELP WITH SOLUTIONS SHOWING A WILD RANGE. BASED ON CLIMATOLOGY...COORDINATION WITH SURROUNDING WFOS...AND BUYING THAT THE HIGHER RESOLUTION OF THE NAM THIS CLOSE IN SHOULD BE SUPERIOR TO THE GFS...ISSUED A WINTER WEATHER ADVISORY FOR THESE AREAS. WE WANT TO STRESS THIS ADVISORY IS NOT FOR THE SNOWFALL AMOUNTS BUT FOR THE SHORT WINDOW OF TIME FROM BETWEEN 22Z THROUGH 03Z WHEN WARM TEMPS ALOFT COMBINED WITH COOLING SURFACE TEMPS WILL ALLOW FOR A PERIOD OF FREEZING RAIN. LATE TONIGHT WE HAVE PLENTY OF MOISTURE IN THE LOW LEVELS BY LACK OF MOISTURE IN THE MID LEVELS (NO ICE CRYSTALS) WILL LIKELY MEAN A FAIRLY RAPID END FROM WEST TO EAST OF ANY PRECIP. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... 600 AM UPDATE... SUNDAY/SUNDAY NIGHT...NOT MUCH CHANGE TO THE PREVIOUS FORECAST. WE REMAIN UNDER THE INFLUENCE OF THE UPPER LEVEL LOW WITH CHANCES FOR LIGHT SNOW MAINLY IN CNY BY SUNDAY AFTERNOON/NIGHT. NOT LOOKING FOR MUCH IN TERMS OF ACCUMS. && .LONG TERM /MONDAY THROUGH FRIDAY/... 345 AM UPDATE... WELCOME TO CUTOFF COUNTRY. A PATTERN MORE REMINISCENT OF EARLY SPRING...THAT IS...AMPLIFIED WITH CUTOFF LOWS...WILL DOMINATE THE LONG TERM PERIOD OF THE FORECAST. DAYTIME TEMPERATURES THOUGH WILL NOT STRAY MUCH FROM CLIMATOLOGY. ECMWF AND GFS AGREE THAT AN UPPER LOW WILL BE SHIFTING ITS WAY UP THE OHIO VALLEY TUESDAY INTO TUESDAY NIGHT. THE DETAILS ARE A BIT DIFFERENT AS TO WHAT HAPPENS FROM THERE...BUT BOTH SHOW A VERSION OF A NORTHERN HIGH PLAINS UPPER TROUGH DIGGING INTO THE MIDWEST AND CAPTURING/CONSOLIDATING WITH THE ORIGINAL UPPER LOW. WHEN THAT OCCURS...IT WILL BE STUCK IN OUR VICINITY AND IN ABSOLUTELY NO RUSH TO GO ANYWHERE THROUGH FRIDAY. FOR US...THAT MEANS PLENTY OF CLOUD COVER...OCCASIONAL SNOW AND/OR RAIN SHOWERS...AND LITTLE MOVEMENT IN TEMPERATURES DIURNALLY. ON THE LEADING EDGE OF THIS PATTERN...MODEL CONSENSUS HAS SHIELD OF PRECIPITATION MOVING IN A BIT SLOWER THAN PREVIOUS FORECAST...MAINLY LATE TUESDAY INTO TUESDAY NIGHT. THIS SLOWER TREND IS NOT A SURPRISE GIVEN AMPLIFIED NATURE TO PATTERN. GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. PRESSURE GRADIENT BETWEEN LARGE DEPARTING NEW ENGLAND HIGH AND INCOMING LOW WILL BE QUITE STEEP...AND I THUS INCREASED WINDS FOR THE TUESDAY NIGHT/EARLY WEDNESDAY PERIOD. NOT SURE YET HOW MUCH OF THE STRONG WINDS ALOFT WILL BE ABLE TO MIX DOWN...THE BOUNDARY LAYER MAY BE FAIRLY STABLE. ONE NOTEWORTHY DIFFERENCE IN THE MODELS IS THAT THE GFS IS COLDER AT 925MB THAN AT 850MB /WHERE IT IS MAINLY ABOVE FREEZING/ AS THE PRECIPITATION MOVES IN TUESDAY. ECMWF MEANWHILE IS VICE- VERSA. SO THE GFS WOULD SUGGEST POSSIBLE FREEZING RAIN WHILE THE ECMWF IS MORE OF A SIMPLE RAIN/SNOW MIX. I HAVE NOT ADDED CHANCE OF FREEZING RAIN TO GRIDS JUST YET...BUT THIS POTENTIAL WILL HAVE TO BE ASSESSED AS THE EVENT GETS CLOSER. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... 12Z UPDATE... COMPLICATED AVIATION FORECAST DURING THIS TAF PERIOD...WITH REGION IN MOIST FEED BETWEEN DEVELOPING LOW AROUND THE MID ATLANTIC COAST...AND ANOTHER LOW IN THE NORTHERN GREAT LAKES. MAINLY MVFR CIGS TODAY...IN MOST CASES FUEL ALT MINS /AND EVEN IFR FOR KBGM/...COURTESY OF MOISTURE TRAPPED UNDER INVERSION. PASSING -SHRA WILL YIELD MVFR VIS AS WELL AT TIMES. BEHIND OCCLUDED FRONT TONIGHT...SATURATED LAYER GETS SQUEEZED BELOW LOWERING INVERSION AND IFR CIGS WILL IMPACT MOST TERMINALS THIS EVENING BEFORE LIMITED IMPROVEMENT TOWARDS DAWN SUNDAY. FREEZING DRIZZLE NOT OUT OF THE QUESTION...WITH SHALLOW SATURATED LAYER STAYING ON THE WARM SIDE WHICH MAY PRESENT DIFFICULTY INTRODUCING SNOW CRYSTALS. .OUTLOOK... SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS. MON...VFR. TUE...MVFR/IFR IN RAIN AND/OR SNOW LATE TUE INTO TUE NIGHT. WED...MVFR IN LAKE ENHANCED SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST SUNDAY FOR PAZ040-048-072. NY...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST SUNDAY FOR NYZ057-062. && $$ SYNOPSIS...HEDEN NEAR TERM...HEDEN/PVN SHORT TERM...HEDEN LONG TERM...MDP AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
646 AM EST SAT FEB 23 2013 .SYNOPSIS... A COMBINATION OF TWO STORM SYSTEMS...ONE TO OUR NORTHWEST AND ANOTHER MOVING UP THE COAST...WILL BRING US UNSETTLED WEATHER TODAY WITH PLENTY OF CLOUDS. MOST OF THE AREA WILL SEE RAIN DEVELOP BY AFTERNOON...BUT SOME WET SNOW IS POSSIBLE ACROSS ONEIDA COUNTY AND THE CATSKILLS. BY TONIGHT AS COLDER AIR MOVES BACK INTO OUR AREA...A PERIOD OF FREEZING RAIN IS POSSIBLE OVER THE CATSKILLS...WITH A GRADUAL TRANSITION FROM RAIN TO SNOW OVER THE ENTIRE AREA BEFORE ENDING. LIGHT SNOW SHOWERS ARE POSSIBLE SUNDAY IN CENTRAL NY WITH DRIER WEATHER BY MONDAY. && .NEAR TERM /THROUGH TONIGHT/... THIS MORNING...AN AREA OF PRECIPITATION MAINLY FROM THE NY/PA LINE NORTH THROUGH THE FINGER LAKES CONTINUES TO MOVE THROUGH OUR AREA. OVER THE PAST 2 HOURS THE INTENSITY ON RADAR OF THIS PRECIP HAS INCREASED. THIS IS LIKELY DUE TO SOME SLEET MIXING IN AS EVIDENT BY LOWER VALUES OF CC ON THE DUAL POL PRODUCTS. THIS IS INDICATING MIXED HYDROMETEORS AND BASED ON SOUNDINGS AND THIS AREA COINCIDING WITH HIGHER RETURNS...SLEET IS THE MOST LIKELY P-TYPE HERE. THE LATEST RUC SEEMS TO OFFER THE BEST HOPE FOR A SHORT TERM FORECAST BASED ON A LOBE OF VORTICITY AT 500 MB MOVING THROUGH...THAT LINES UP WELL WITH THE PRECIP. THE RUC MOVES THIS OFF TO THE NORTHEAST BY 12Z. BASED ON RADAR TRENDS THOUGH MAY SLOW THIS DOWN A TAD. PRECIP INTENSITY WILL BE RELATIVELY LIGHT AS WILL QPF AMOUNTS. WE ARE LACKING ICE IN THE CLOUD SO P-TYPE LOOKS TO BE MAINLY RAIN OR SOME ICE PELLETS EXCEPT ACROSS THE FAR NORTH AND EAST WHERE SLIGHTLY DEEPER MOISTURE PROFILES ALLOW FOR SOME SNOW. ISOLATED POCKETS OF FREEZING RAIN ARE POSSIBLE BUT IT APPEARS WHERE THE LIQUID PRECIP IS MOST LIKELY...TEMPS ARE ALREADY NEAR OR ABOVE FREEZING. WHERE WE HAVE COLDER SURFACE TEMPS...MOISTURE ALOFT SUPPORTS MORE SNOW. AFTER THIS MOVES THROUGH WE MAY SEE A LULL FOR A FEW HOURS FOR MOST OF US. LATER THIS MORNING/TONIGHT...NEXT FEATURES OF INTEREST WILL BE AN AREA OF LOW PRESSURE MOVING THROUGH THE GREAT LAKES AND AN AREA OF LOW PRESSURE NOW TAKING SHAPE OFF THE CAROLINA COAST. OUR AREA WILL BE IN ON THE SQUEEZE PLAY TODAY WITH INCREASING MOISTURE FROM BOTH THE WEST (GREAT LAKES SYSTEM) AND EAST (COASTAL SYSTEM). MAIN ADJUSTMENT WAS TO TRIM BACK POPS IN THE MIDDLE TODAY...AND PUSH BACK THE BEST SHOT AT WIDESPREAD PRECIPITATION INTO THE 18Z - 22Z RANGE. OVERALL THOUGH LOOKING AT A FAIRLY LIGHT QPF EVENT WITH AROUND AMOUNTS RANGING FROM A TENTH TO TWO TENTHS. THE FIRST TRIGGER FOR PRECIP WILL COME BY LATE MORNING AS A RIBBON OF PVA SLIDES INTO WESTERN NY...IN THE FLOW AROUND THE PARENT UPPER LOW OVER THE GREAT LAKES. THIS WILL MOVE ACROSS THE REST OF THE AREA TOWARD 20Z...AS WE ALSO GETTING INCREASING UPPER LEVEL LIFT OVER THE FAR SOUTHEAST IN RESPONSE TO THE COASTAL LOW. I RAMP POPS UP GREATLY IN THE 22Z TO 0Z PERIOD TO SHOW OUR BEST SHOT AT PRECIPITATION ACROSS MOST OF THE AREA AS THIS HAPPENS. AS FAR AS P-TYPE GOES...A TONGUE OF WARMER AIR AROUND 800 MB WILL KEEP US MOSTLY RAIN THROUGH LATE THIS AFTERNOON. THE EXCEPTION WILL BE ACROSS NORTHERN ONEIDA COUNTY WHERE TEMPS ALOFT NEVER GET ABOVE 0C...SO AT THE VERY LEAST A RAIN/SNOW MIX IS LIKELY IF NOT MOSTLY SNOW...ALL DAY. WE COULD SEE UP TO 2 INCHES HERE THROUGH AFTERNOON ACROSS THE HIGHER TERRAIN. OVER THE FAR EAST SNOW IS POSSIBLE EARLY BUT EVEN HERE TEMPS ALOFT WARM UP ABOVE 0C AFTER 21Z. DURING THIS TIME SOME AREAS OF FREEZING RAIN ARE POSSIBLE IN OUR NORMALLY COLDEST SECTIONS...WITH PLAIN RAIN OR A FEW SLEET PELLETS POSSIBLE ELSEWHERE. TONIGHT...AS THE COASTAL SYSTEM DEEPENS AND MOVES WELL OUT TO SEA...COLDER AIR ALOFT WILL RAPIDLY MOVE IN FROM THE WEST. THIS WILL CHANGE OUR RAIN OVER TO A PERIOD OF LIGHT SNOW BEFORE ENDING OVERNIGHT. ACCUMS EXPECTED TO BE AROUND AN INCH OR LESS. THE TRICKY SPOT WILL BE ROUGHLY FROM DELAWARE COUNTY SOUTH THROUGH WAYNE AND PIKE COUNTIES...WHERE TEMPS ALOFT WILL REMAIN ABOVE 0C THROUGH 03Z THIS EVENING. NAM SOUNDINGS HAVE REMAINED CONSISTENT SINCE LAST NIGHT SHOWING SOME BOUNDARY LAYER COOLING DURING THIS TIME ALLOWING SURFACE TEMPS TO BE NEAR OR SLIGHTLY BELOW FREEZING. GFS PROFILES COULD NOT BE MORE DIFFERENT WITH TEMPS REMAINING ABOVE FREEZING AT THE SURFACE...BEFORE A RAPID TRANSITION FROM RAIN TO SNOW...WITH NO PERIOD OF FREEZING RAIN. SREF PROFILES PROVIDE LITTLE HELP WITH SOLUTIONS SHOWING A WILD RANGE. BASED ON CLIMATOLOGY...COORDINATION WITH SURROUNDING WFOS...AND BUYING THAT THE HIGHER RESOLUTION OF THE NAM THIS CLOSE IN SHOULD BE SUPERIOR TO THE GFS...ISSUED A WINTER WEATHER ADVISORY FOR THESE AREAS. WE WANT TO STRESS THIS ADVISORY IS NOT FOR THE SNOWFALL AMOUNTS BUT FOR THE SHORT WINDOW OF TIME FROM BETWEEN 22Z THROUGH 03Z WHEN WARM TEMPS ALOFT COMBINED WITH COOLING SURFACE TEMPS WILL ALLOW FOR A PERIOD OF FREEZING RAIN. LATE TONIGHT WE HAVE PLENTY OF MOISTURE IN THE LOW LEVELS BY LACK OF MOISTURE IN THE MID LEVELS (NO ICE CRYSTALS) WILL LIKELY MEAN A FAIRLY RAPID END FROM WEST TO EAST OF ANY PRECIP. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... 600 AM UPDATE... SUNDAY/SUNDAY NIGHT...NOT MUCH CHANGE TO THE PREVIOUS FORECAST. WE REMAIN UNDER THE INFLUENCE OF THE UPPER LEVEL LOW WITH CHANCES FOR LIGHT SNOW MAINLY IN CNY BY SUNDAY AFTERNOON/NIGHT. NOT LOOKING FOR MUCH IN TERMS OF ACCUMS. && .LONG TERM /MONDAY THROUGH FRIDAY/... 345 AM UPDATE... WELCOME TO CUTOFF COUNTRY. A PATTERN MORE REMINISCENT OF EARLY SPRING...THAT IS...AMPLIFIED WITH CUTOFF LOWS...WILL DOMINATE THE LONG TERM PERIOD OF THE FORECAST. DAYTIME TEMPERATURES THOUGH WILL NOT STRAY MUCH FROM CLIMATOLOGY. ECMWF AND GFS AGREE THAT AN UPPER LOW WILL BE SHIFTING ITS WAY UP THE OHIO VALLEY TUESDAY INTO TUESDAY NIGHT. THE DETAILS ARE A BIT DIFFERENT AS TO WHAT HAPPENS FROM THERE...BUT BOTH SHOW A VERSION OF A NORTHERN HIGH PLAINS UPPER TROUGH DIGGING INTO THE MIDWEST AND CAPTURING/CONSOLIDATING WITH THE ORIGINAL UPPER LOW. WHEN THAT OCCURS...IT WILL BE STUCK IN OUR VICINITY AND IN ABSOLUTELY NO RUSH TO GO ANYWHERE THROUGH FRIDAY. FOR US...THAT MEANS PLENTY OF CLOUD COVER...OCCASIONAL SNOW AND/OR RAIN SHOWERS...AND LITTLE MOVEMENT IN TEMPERATURES DIURNALLY. ON THE LEADING EDGE OF THIS PATTERN...MODEL CONSENSUS HAS SHIELD OF PRECIPITATION MOVING IN A BIT SLOWER THAN PREVIOUS FORECAST...MAINLY LATE TUESDAY INTO TUESDAY NIGHT. THIS SLOWER TREND IS NOT A SURPRISE GIVEN AMPLIFIED NATURE TO PATTERN. GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. PRESSURE GRADIENT BETWEEN LARGE DEPARTING NEW ENGLAND HIGH AND INCOMING LOW WILL BE QUITE STEEP...AND I THUS INCREASED WINDS FOR THE TUESDAY NIGHT/EARLY WEDNESDAY PERIOD. NOT SURE YET HOW MUCH OF THE STRONG WINDS ALOFT WILL BE ABLE TO MIX DOWN...THE BOUNDARY LAYER MAY BE FAIRLY STABLE. ONE NOTEWORTHY DIFFERENCE IN THE MODELS IS THAT THE GFS IS COLDER AT 925MB THAN AT 850MB /WHERE IT IS MAINLY ABOVE FREEZING/ AS THE PRECIPITATION MOVES IN TUESDAY. ECMWF MEANWHILE IS VICE- VERSA. SO THE GFS WOULD SUGGEST POSSIBLE FREEZING RAIN WHILE THE ECMWF IS MORE OF A SIMPLE RAIN/SNOW MIX. I HAVE NOT ADDED CHANCE OF FREEZING RAIN TO GRIDS JUST YET...BUT THIS POTENTIAL WILL HAVE TO BE ASSESSED AS THE EVENT GETS CLOSER. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... 12Z UPDATE... COMPLICATED AVIATION FORECAST DURING THIS TAF PERIOD...WITH REGION IN MOIST FEED BETWEEN DEVELOPING LOW AROUND THE MID ATLANTIC COAST...AND ANOTHER LOW IN THE NORTHERN GREAT LAKES. MAINLY MVFR CIGS TODAY...IN MOST CASES FUEL ALT MINS /AND EVEN IFR FOR KBGM/...COURTESY OF MOISTURE TRAPPED UNDER INVERSION. PASSING -SHRA WILL YIELD MVFR VIS AS WELL AT TIMES. BEHIND OCCLUDED FRONT TONIGHT...SATURATED LAYER GETS SQUEEZED BELOW LOWERING INVERSION AND IFR CIGS WILL IMPACT MOST TERMINALS THIS EVENING BEFORE LIMITED IMPROVEMENT TOWARDS DAWN SUNDAY. FREEZING DRIZZLE NOT OUT OF THE QUESTION...WITH SHALLOW SATURATED LAYER STAYING ON THE WARM SIDE WHICH MAY PRESENT DIFFICULTY INTRODUCING SNOW CRYSTALS. .OUTLOOK... SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS. MON...VFR. TUE...MVFR/IFR IN RAIN AND/OR SNOW LATE TUE INTO TUE NIGHT. WED...MVFR IN LAKE ENHANCED SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST SUNDAY FOR PAZ040-048-072. NY...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST SUNDAY FOR NYZ057-062. && $$ SYNOPSIS...HEDEN NEAR TERM...HEDEN SHORT TERM...HEDEN LONG TERM...MDP AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
610 AM EST SAT FEB 23 2013 .SYNOPSIS... A COMBINATION OF TWO STORM SYSTEMS...ONE TO OUR NORTHWEST AND ANOTHER MOVING UP THE COAST...WILL BRING US UNSETTLED WEATHER TODAY WITH PLENTY OF CLOUDS. MOST OF THE AREA WILL SEE RAIN DEVELOP BY AFTERNOON...BUT SOME WET SNOW IS POSSIBLE ACROSS ONEIDA COUNTY AND THE CATSKILLS. BY TONIGHT AS COLDER AIR MOVES BACK INTO OUR AREA...A PERIOD OF FREEZING RAIN IS POSSIBLE OVER THE CATSKILLS...WITH A GRADUAL TRANSITION FROM RAIN TO SNOW OVER THE ENTIRE AREA BEFORE ENDING. LIGHT SNOW SHOWERS ARE POSSIBLE SUNDAY IN CENTRAL NY WITH DRIER WEATHER BY MONDAY. && .NEAR TERM /THROUGH TONIGHT/... THIS MORNING...AN AREA OF PRECIPITATION MAINLY FROM THE NY/PA LINE NORTH THROUGH THE FINGER LAKES CONTINUES TO MOVE THROUGH OUR AREA. OVER THE PAST 2 HOURS THE INTENSITY ON RADAR OF THIS PRECIP HAS INCREASED. THIS IS LIKELY DUE TO SOME SLEET MIXING IN AS EVIDENT BY LOWER VALUES OF CC ON THE DUAL POL PRODUCTS. THIS IS INDICATING MIXED HYDROMETEORS AND BASED ON SOUNDINGS AND THIS AREA COINCIDING WITH HIGHER RETURNS...SLEET IS THE MOST LIKELY P-TYPE HERE. THE LATEST RUC SEEMS TO OFFER THE BEST HOPE FOR A SHORT TERM FORECAST BASED ON A LOBE OF VORTICITY AT 500 MB MOVING THROUGH...THAT LINES UP WELL WITH THE PRECIP. THE RUC MOVES THIS OFF TO THE NORTHEAST BY 12Z. BASED ON RADAR TRENDS THOUGH MAY SLOW THIS DOWN A TAD. PRECIP INTENSITY WILL BE RELATIVELY LIGHT AS WILL QPF AMOUNTS. WE ARE LACKING ICE IN THE CLOUD SO P-TYPE LOOKS TO BE MAINLY RAIN OR SOME ICE PELLETS EXCEPT ACROSS THE FAR NORTH AND EAST WHERE SLIGHTLY DEEPER MOISTURE PROFILES ALLOW FOR SOME SNOW. ISOLATED POCKETS OF FREEZING RAIN ARE POSSIBLE BUT IT APPEARS WHERE THE LIQUID PRECIP IS MOST LIKELY...TEMPS ARE ALREADY NEAR OR ABOVE FREEZING. WHERE WE HAVE COLDER SURFACE TEMPS...MOISTURE ALOFT SUPPORTS MORE SNOW. AFTER THIS MOVES THROUGH WE MAY SEE A LULL FOR A FEW HOURS FOR MOST OF US. LATER THIS MORNING/TONIGHT...NEXT FEATURES OF INTEREST WILL BE AN AREA OF LOW PRESSURE MOVING THROUGH THE GREAT LAKES AND AN AREA OF LOW PRESSURE NOW TAKING SHAPE OFF THE CAROLINA COAST. OUR AREA WILL BE IN ON THE SQUEEZE PLAY TODAY WITH INCREASING MOISTURE FROM BOTH THE WEST (GREAT LAKES SYSTEM) AND EAST (COASTAL SYSTEM). MAIN ADJUSTMENT WAS TO TRIM BACK POPS IN THE MIDDLE TODAY...AND PUSH BACK THE BEST SHOT AT WIDESPREAD PRECIPITATION INTO THE 18Z - 22Z RANGE. OVERALL THOUGH LOOKING AT A FAIRLY LIGHT QPF EVENT WITH AROUND AMOUNTS RANGING FROM A TENTH TO TWO TENTHS. THE FIRST TRIGGER FOR PRECIP WILL COME BY LATE MORNING AS A RIBBON OF PVA SLIDES INTO WESTERN NY...IN THE FLOW AROUND THE PARENT UPPER LOW OVER THE GREAT LAKES. THIS WILL MOVE ACROSS THE REST OF THE AREA TOWARD 20Z...AS WE ALSO GETTING INCREASING UPPER LEVEL LIFT OVER THE FAR SOUTHEAST IN RESPONSE TO THE COASTAL LOW. I RAMP POPS UP GREATLY IN THE 22Z TO 0Z PERIOD TO SHOW OUR BEST SHOT AT PRECIPITATION ACROSS MOST OF THE AREA AS THIS HAPPENS. AS FAR AS P-TYPE GOES...A TONGUE OF WARMER AIR AROUND 800 MB WILL KEEP US MOSTLY RAIN THROUGH LATE THIS AFTERNOON. THE EXCEPTION WILL BE ACROSS NORTHERN ONEIDA COUNTY WHERE TEMPS ALOFT NEVER GET ABOVE 0C...SO AT THE VERY LEAST A RAIN/SNOW MIX IS LIKELY IF NOT MOSTLY SNOW...ALL DAY. WE COULD SEE UP TO 2 INCHES HERE THROUGH AFTERNOON ACROSS THE HIGHER TERRAIN. OVER THE FAR EAST SNOW IS POSSIBLE EARLY BUT EVEN HERE TEMPS ALOFT WARM UP ABOVE 0C AFTER 21Z. DURING THIS TIME SOME AREAS OF FREEZING RAIN ARE POSSIBLE IN OUR NORMALLY COLDEST SECTIONS...WITH PLAIN RAIN OR A FEW SLEET PELLETS POSSIBLE ELSEWHERE. TONIGHT...AS THE COASTAL SYSTEM DEEPENS AND MOVES WELL OUT TO SEA...COLDER AIR ALOFT WILL RAPIDLY MOVE IN FROM THE WEST. THIS WILL CHANGE OUR RAIN OVER TO A PERIOD OF LIGHT SNOW BEFORE ENDING OVERNIGHT. ACCUMS EXPECTED TO BE AROUND AN INCH OR LESS. THE TRICKY SPOT WILL BE ROUGHLY FROM DELAWARE COUNTY SOUTH THROUGH WAYNE AND PIKE COUNTIES...WHERE TEMPS ALOFT WILL REMAIN ABOVE 0C THROUGH 03Z THIS EVENING. NAM SOUNDINGS HAVE REMAINED CONSISTENT SINCE LAST NIGHT SHOWING SOME BOUNDARY LAYER COOLING DURING THIS TIME ALLOWING SURFACE TEMPS TO BE NEAR OR SLIGHTLY BELOW FREEZING. GFS PROFILES COULD NOT BE MORE DIFFERENT WITH TEMPS REMAINING ABOVE FREEZING AT THE SURFACE...BEFORE A RAPID TRANSITION FROM RAIN TO SNOW...WITH NO PERIOD OF FREEZING RAIN. SREF PROFILES PROVIDE LITTLE HELP WITH SOLUTIONS SHOWING A WILD RANGE. BASED ON CLIMATOLOGY...COORDINATION WITH SURROUNDING WFOS...AND BUYING THAT THE HIGHER RESOLUTION OF THE NAM THIS CLOSE IN SHOULD BE SUPERIOR TO THE GFS...ISSUED A WINTER WEATHER ADVISORY FOR THESE AREAS. WE WANT TO STRESS THIS ADVISORY IS NOT FOR THE SNOWFALL AMOUNTS BUT FOR THE SHORT WINDOW OF TIME FROM BETWEEN 22Z THROUGH 03Z WHEN WARM TEMPS ALOFT COMBINED WITH COOLING SURFACE TEMPS WILL ALLOW FOR A PERIOD OF FREEZING RAIN. LATE TONIGHT WE HAVE PLENTY OF MOISTURE IN THE LOW LEVELS BY LACK OF MOISTURE IN THE MID LEVELS (NO ICE CRYSTALS) WILL LIKELY MEAN A FAIRLY RAPID END FROM WEST TO EAST OF ANY PRECIP. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... 600 AM UPDATE... SUNDAY/SUNDAY NIGHT...NOT MUCH CHANGE TO THE PREVIOUS FORECAST. WE REMAIN UNDER THE INFLUENCE OF THE UPPER LEVEL LOW WITH CHANCES FOR LIGHT SNOW MAINLY IN CNY BY SUNDAY AFTERNOON/NIGHT. NOT LOOKING FOR MUCH IN TERMS OF ACCUMS. && .LONG TERM /MONDAY THROUGH FRIDAY/... 345 AM UPDATE... WELCOME TO CUTOFF COUNTRY. A PATTERN MORE REMINISCENT OF EARLY SPRING...THAT IS...AMPLIFIED WITH CUTOFF LOWS...WILL DOMINATE THE LONG TERM PERIOD OF THE FORECAST. DAYTIME TEMPERATURES THOUGH WILL NOT STRAY MUCH FROM CLIMATOLOGY. ECMWF AND GFS AGREE THAT AN UPPER LOW WILL BE SHIFTING ITS WAY UP THE OHIO VALLEY TUESDAY INTO TUESDAY NIGHT. THE DETAILS ARE A BIT DIFFERENT AS TO WHAT HAPPENS FROM THERE...BUT BOTH SHOW A VERSION OF A NORTHERN HIGH PLAINS UPPER TROUGH DIGGING INTO THE MIDWEST AND CAPTURING/CONSOLIDATING WITH THE ORIGINAL UPPER LOW. WHEN THAT OCCURS...IT WILL BE STUCK IN OUR VICINITY AND IN ABSOLUTELY NO RUSH TO GO ANYWHERE THROUGH FRIDAY. FOR US...THAT MEANS PLENTY OF CLOUD COVER...OCCASIONAL SNOW AND/OR RAIN SHOWERS...AND LITTLE MOVEMENT IN TEMPERATURES DIURNALLY. ON THE LEADING EDGE OF THIS PATTERN...MODEL CONSENSUS HAS SHIELD OF PRECIPITATION MOVING IN A BIT SLOWER THAN PREVIOUS FORECAST...MAINLY LATE TUESDAY INTO TUESDAY NIGHT. THIS SLOWER TREND IS NOT A SURPRISE GIVEN AMPLIFIED NATURE TO PATTERN. GRIDS HAVE BEEN ADJUSTED ACCORDINGLY. PRESSURE GRADIENT BETWEEN LARGE DEPARTING NEW ENGLAND HIGH AND INCOMING LOW WILL BE QUITE STEEP...AND I THUS INCREASED WINDS FOR THE TUESDAY NIGHT/EARLY WEDNESDAY PERIOD. NOT SURE YET HOW MUCH OF THE STRONG WINDS ALOFT WILL BE ABLE TO MIX DOWN...THE BOUNDARY LAYER MAY BE FAIRLY STABLE. ONE NOTEWORTHY DIFFERENCE IN THE MODELS IS THAT THE GFS IS COLDER AT 925MB THAN AT 850MB /WHERE IT IS MAINLY ABOVE FREEZING/ AS THE PRECIPITATION MOVES IN TUESDAY. ECMWF MEANWHILE IS VICE- VERSA. SO THE GFS WOULD SUGGEST POSSIBLE FREEZING RAIN WHILE THE ECMWF IS MORE OF A SIMPLE RAIN/SNOW MIX. I HAVE NOT ADDED CHANCE OF FREEZING RAIN TO GRIDS JUST YET...BUT THIS POTENTIAL WILL HAVE TO BE ASSESSED AS THE EVENT GETS CLOSER. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/... 06Z UPDATE... COMPLICATED AVIATION FORECAST DURING THIS TAF PERIOD...WITH REGION IN MOIST FEED BETWEEN DEVELOPING LOW AROUND THE MID ATLANTIC COAST...AND ANOTHER LOW IN THE NORTHERN GREAT LAKES. LOW END VFR TO MVFR CIGS...COURTESY OF SHALLOW MOISTURE WHICH WILL OCCASIONALLY YIELD PATCHY FREEZING DRIZZLE KAVP-KBGM-KELM LATER THIS MORNING...BRIEF IFR CIG ALSO NOT OUT OF THE QUESTION LATER THIS MORNING FOR KBGM /AFTER 12Z/. CIGS GENERALLY STAY IN MVFR CATEGORY WITH LIGHT RAIN OR DRIZZLE DURING THE DAY CAUSING MVFR VIS AS OCCLUDED FRONT PASSES OVERHEAD WITH CONTINUED SHALLOW MOISTURE. BEHIND OCCLUDED FRONT TONIGHT...SATURATED LAYER GETS SQUEEZED BELOW LOWERING INVERSION AND IFR CIGS MAY IMPACT MOST TERMINALS. FREEZING DRIZZLE MAY ALSO RE-ENTER THE PICTURE. .OUTLOOK... LATE SAT NGT...MVFR/IFR IN MIXED PCPN. SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS. MON...VFR. TUE...MVFR/IFR IN RAIN AND/OR SNOW. WED...MVFR IN LAKE ENHANCED SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST SUNDAY FOR PAZ040-048-072. NY...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST SUNDAY FOR NYZ057-062. && $$ SYNOPSIS...HEDEN NEAR TERM...HEDEN SHORT TERM...HEDEN LONG TERM...MDP AVIATION...MDP
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
1017 AM EST SAT FEB 23 2013 .DISCUSSION... RAIN HAS EXITED THE AREA...AND A SLOW MOVING FRONT WILL BE BRINGING DRIER AIR FROM THE WEST THROUGH THE DAY. SATELLITE SHOWS BROKEN CLOUDS NORTHWEST...AND THE LATEST RUC SHOWS RH CONTINUING TO DECREASE THROUGH THE AFTERNOON. THE 12Z OHX SOUNDING SHOWS A THIN MOIST LAYER...HOWEVER DRY ADVECTION WILL BE WEAK AS WINDS IN THIS LAYER ARE LIGHT. THE TRICKY PART WILL BE HOW MUCH TEMPS WILL RISE THROUGH BROKEN CLOUDS BEFORE SUNSET. THE LATEST 06Z GFS MOS GUIDANCE AND LAMP GUIDANCE ARE COOLER THAN THE CURRENT FORECAST...ESPECIALLY NORTH...SO WILL MAKE A SLIGHT DOWNWARD ADJUSTMENT TO TEMPS. LOWER 60S WILL STILL BE POSSIBLE IN THE SOUTHERN VALLEY...WITH MID TO UPPER 50S NORTH AND CENTRAL. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DGS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
530 AM CST SAT FEB 23 2013 .SHORT TERM...TODAY THROUGH MONDAY NIGHT 319 AM CST SAT FEB 23 2013 FORECAST CHALLENGES GOING THROUGH EARLY NEXT WEEK REVOLVE AROUND WHEN THE FLURRIES/SKIES CLEAR OUT TODAY/TONIGHT ALONG WITH WHEN THE NEXT ROUND OF LIGHT SNOW MAY MOVE IN ON MONDAY. CYCLONIC FLOW FROM THE SURFACE THROUGH THE UPPER ATMOSPHERE WILL LINGER ACROSS THE REGION FOR MUCH OF TODAY BEFORE A SURFACE TO UPPER LEVEL RIDGE AXIS PROPAGATES IN FROM THE WEST TONIGHT. WITH THE CYCLONIC FLOW HANGING ON FOR MUCH OF TODAY...EXPECT THAT THE CLOUD COVER AND FLURRIES/SNOW SHOWERS WILL CONTINUE AS WELL AND THAT THE DRY AIR TO THE SOUTHWEST WILL STRUGGLE TO MOVE IN. BY 00Z TONIGHT...THE 23.07Z RAP HAS THE SURFACE RIDGE ALIGNED ALONG THE MISSISSIPPI RIVER...SO AT LEAST EXPECT THAT THE FLURRIES WILL HAVE ENDED BY THEN ALONG AND WEST OF THE RIVER. HOWEVER...CLOUD COVER MAY LINGER WITH THE UPPER RIDGE STILL IN THE DAKOTAS. HAVE PLAYED CLOUD COVER A BIT ON THE PESSIMISTIC SIDE THROUGH TONIGHT AS A RESULT. BEYOND THIS THE PATTERN IS FAIRLY QUIET THROUGH THE REST OF THE WEEKEND AS THE RIDGE SHIFTS TO THE EAST WITH TEMPERATURES AND CLOUD COVER THE ONLY ISSUES TO CONTEND WITH. THERE IS NOT MUCH IN THE WAY OF LOW LEVEL COLD AIR ADVECTION KICKING IN BEHIND THIS SYSTEM...SO EXPECT THAT TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH MONDAY NIGHT. THE FOCUS THEN GOES TO THE NEXT SYSTEM THAT COULD IMPACT THE AREA WHICH IS A COMBINATION OF A NORTHERN STREAM WEAKENING MID LEVEL SHORT WAVE TROUGH AND A SOUTHERN STREAM DEEPENING LOW. THE TREND CONTINUES TO BE TO GO SLOWER WITH THE NORTHERN STREAM SHORT WAVE AS A BLOCKING RIDGE ALONG THE ATLANTIC COAST STALLS OUT THE FLOW. THE SURFACE REFLECTION FROM THIS SYSTEM IS A TROUGH THAT TRACKS ACROSS THE DAKOTAS AND STALLS ACROSS MINNESOTA AS THE SOUTHERN STREAM SYSTEM STARTS TO DEEPEN. THE 23.00Z GFS IS THE MOST ROBUST WITH QPF EXTENDING NORTH ALONG THIS SURFACE TROUGH WHILE THE REST OF THE GUIDANCE IS DRY. THEREFORE...HAVE BACKED OFF ON PRECIPITATION CHANCES FOR MONDAY NIGHT AND KEPT THEM RELEGATED TO PORTIONS OF SOUTH CENTRAL MINNESOTA INTO NORTHEAST IOWA. .LONG TERM...TUESDAY THROUGH FRIDAY 319 AM CST SAT FEB 23 2013 THIS AFOREMENTIONED SOUTHERN STREAM SYSTEM APPEARS TO BE COMING TOGETHER BY TUESDAY WITH THE 23.00Z GUIDANCE LOCKING IN ON A MORE SOUTHERN TRACK WITH THIS SURFACE LOW. THE 23.00Z GFS/ECMWF/GEM ALL ADVERTISE THIS LOW RUNNING FROM ST LOUIS OVER TO INDIANAPOLIS TUESDAY WHICH SHOULD KEEP THE MAIN BAND OF SNOW OFF TO THE SOUTHEAST. THE 23.00Z GFS IS FURTHEST TO THE NORTHWEST WHILE THE GEM/ECMWF ARE NEARLY IDENTICAL WITH THEIR TRACK. HAVE BACKED OFF ON SNOW CHANCES FOR TUESDAY ACROSS SOUTHWEST WISCONSIN AS A RESULT. AFTER THIS SYSTEM MOVES THROUGH...ANOTHER MID LEVEL TROUGH WILL DIG DOWN THROUGH THE NORTHWEST FLOW AND REINFORCE THE CUT OFF CLOSED LOW ACROSS THE EASTERN US. THIS WILL KEEP CYCLONIC FLOW IN PLACE ACROSS THE REGION THROUGH THURSDAY WITH SOME LIGHT SNOW POSSIBLE. THE 23.00Z GEM IS THE DRIEST OF THE GUIDANCE AND FOCUSES THIS TROUGH FURTHER TO THE SOUTH AND WOULD KEEP THE REGION ON THE DRY SIDE. DESPITE THESE HIGHLY AMPLIFIED SYSTEMS MOVING THROUGH THE UPPER MIDWEST...THE MAIN POOL OF COLD ARCTIC AIR IS CONFINED TO FAR NORTHERN CANADA WITH 850MB TEMPERATURES IN THE 0C TO -10C RANGE ACROSS THE SOUTHERN HALF OF CANADA. THUS...IT DOES NOT LOOK LIKE TEMPERATURES WILL TAKE MUCH OF A DIP AROUND HERE AS THE NORTHERLY FLOW SETS UP TOWARD MID WEEK. && .AVIATION...TODAY AND TONIGHT. 530 AM CST SAT FEB 23 2013 MVFR CIGS AND LCL MVFR VSBYS IN -SN WILL GIVE WAY TO VFR CIGS/VSBYS THIS MORNING AS THE BROAD SFC-MID LEVEL LOW AND ITS CIRCULATION CENTERED OVER NORTHERN LK MI CONTINUES TO DRIFT OFF TO THE EAST TODAY. BIGGER QUESTION IS HOW QUICKLY WILL THE CLOUDS DECREASE/ 3K-5K FT CLOUD DECKS BECOME SCT THIS AFTERNOON OR EVENING. FOG- PRODUCT IMAGERY SHOWING THE WESTERN EDGE OF THE CLOUDS NEAR AK KBDH-KULM-KMCW LINE AT 11Z...MAKING SOME PROGRESS EAST WITH WESTERLY SFC-925MB FLOW. HOWEVER MODELS HANG ONTO PLENTIFUL SFC-850MB RH INTO THIS EVENING AT THE TAF SITES. LEFT CLOUDS BKN THRU TODAY WITH CLOUDS BECOMING SCT DURING THE EVENING. WINDS WILL BE LIGHT TONIGHT. WITH DECREASING CLOUDS OVER THE FRESH SNOW...THE LINGERING VERY LOW LEVEL/BOUNDARY LAYER MOISTURE UNDER A STRENGTHENING SFC-925MB INVERSION IS CONCERN FOR BR DEVELOPMENT LATE TONIGHT...ESPECIALLY AT SITES LIKE KRST. INTRODUCED SOME MVFR BR AT KRST AFTER 07Z. FAVORABLE SET-UP FOR RIMING/HOAR FROST FORMATION LATER TONIGHT INTO SUN MORNING AT SITES WHERE ANY FOG DOES FORM. && .ARX WATCHES/WARNINGS/ADVISORIES... 319 AM CST SAT FEB 23 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM....HALBACH AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
330 PM MST SAT FEB 23 2013 .SHORT TERM....CURRENT WATER VAPOR AND Q-G ANALYSIS SHOWS A STRONG STORM SYSTEM CARVING OUT ACROSS THE GREAT BASIN. LATEST MODEL TRENDS FROM THE 12Z NAM...GFS...GEM AND EVEN WRF HAVE SHOWN A SLIGHT NORTHWARD SHIFT IN AREAS OF BEST LIFT AND HEAVIER SNOWFALL. HOWEVER...12Z ECMWF STILL MAINTAINED A PERSISTENT AND PREFERRED SOLUTION BUT AT THE SAME TIME HAS INCREASED SNOWFALL AMOUNTS AN INCH OR TWO MORE THAN THE 00Z RUN. NCEP FORECASTERS WITH ACCESS TO 00Z EC ENSEMBLE MEMBERS NOTED THAT SOME UNCERTAINTY EVEN REGARDED THE SLIGHTLY FARTHER SOUTH ECMWF SOLUTION...BUT Q-G HEIGHT FALL ANALYSIS FROM THE RUC INDICATES THE OPERATION ECMWF SEEMS QUITE REASONABLE. THE ONLY ARGUMENT WOULD BE IF A MID LEVEL CIRCULATION CENTER PERHAPS RELATED TO LARGER LATENT HEAT RELEASE WOULD RESULT IN A MORE NORTHERLY SOLUTION. AT THIS TIME...HAVE STILL LEANED HEAVILY TOWARD THE ECMWF...BUT ALSO INCORPORATED A BIT OF THE MESOSCALE/SREF MODEL SOLUTIONS. ALL OF THESE FACTORS ADD UP TO A HIGH POTENTIAL FOR A HEAVY SNOW EVENT. THEY INCLUDE...NEUTRAL STABILITY PROFILES...AVERAGE OF 25-30 KTS OF NNE UPSLOPE FLOW...DEEP UPSLOPE COMPONENT WELL ABOVE MOUNTAIN TOP...GOOD MICROPHYSICS WITH LARGE OMEGA THROUGH THE DENDRITIC GROWTH REGION...AND A 12-18 HOUR PERIOD OF MODERATE Q-G VERTICAL MOTION. THIS ALL SUPPORTS THE UPGRADE OF BLIZZARD WATCHES TO WARNING...WINTER STORM WATCHES TO WINTER STORM WARNINGS...AND MOST OTHER LOCATIONS TO WINTER WEATHER ADVISORIES FOR SNOW AND BLOWING SNOW. THE OVERALL BLENDING USING A MAJORITY OF THE ECMWF WITH A LITTLE BIT OF MESOSCALE/SREF MODELS SUPPORT THE FOLLOWING AMOUNTS...6-10 INCHES FOR DENVER/BOULDER AREA...8-12 INCHES PALMER DIVIDE...7-14 INCHES FOOTHILLS...AND 4-8 INCHES THROUGH SOUTHERN WELD...MORGAN...TOWARD WASHINGTON/LINCOLN COUNTY. .LONG TERM...THE BRUNT OF SUNDAY`S STORM SHOULD BE GETTING CLOSE TO ENDING BY THE BEGINNING OF THE LONG TERM PERIOD 25/00Z. THERE WILL PROBABLY STILL BE SOME SNOW OVER THE SOUTHEAST THIRD OR SO OF THE CWA DURING THE EVENING BUT THAT WILL FLUSH OUT TOWARDS MORNING. SURFACE PRESSURE GRADIENTS WILL REMAIN SUFFICIENT TO KEEP GUSTY WINDS OVER MANY LOWER ELEVATIONS IN THE EVENING BUT THESE TOO WILL SETTLE DOWN OVERNIGHT. ONLY A QUICK BREAK IN THINGS AS A SHORT WAVE RIDGE MOVES IN FOR MONDAY WITH THE NEXT PACIFIC SYSTEM IMPACTING OUR WEATHER ON TUESDAY. THIS WILL BE MAINLY A MOUNTAIN EVENT BUT ENOUGH QG LIFT BLEEDS OVER THE HILLS TO BRING A THREAT OF PRECIPITATION TO THE PLAINS TUESDAY. ANOTHER WEAKER SYSTEM IS PROGGED TO PUSH OVER THE CENTRAL ROCKIES THURSDAY...AGAIN BEING MAINLY A PRECIPITATION PRODUCER FOR THE HIGH COUNTRY. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH MOST OF THE WEEK BUT SHOULD APPROACH NORMAL TOWARD WEEK`S AS A STRONG RIDGE ALOFT BUILDS INTO THE GREAT BASIN. THE MOUNTAINS AND FOOTHILLS WILL ALSO EXPERIENCE SOME WINDY PERIODS AS THE FLOW ALOFT BECOMES NORTHWESTERLY. && .AVIATION...SIGNIFICANT AVIATION IMPACTS EXPECTED FROM THIS WINTER STORM. CEILINGS AND VISIBILITIES WILL TUMBLE TONIGHT AND REMAIN VERY LOW THROUGH MOST OF SUNDAY. ONSET TIMING OF THIS IS STILL RATHER DIFFICULT...BUT WE SHOULD SEE SNOW DEVELOPING IN THE FRONT RANGE AIRPORTS MOST LIKELY BETWEEN 05Z AND 08Z...WITH VLIFR CONDITIONS BY 09Z-11Z WHEN SNOWFALL RATES INCREASE TO AROUND 1 INCH PER. THE HEAVY SNOW WILL LIKELY CONTINUE THROUGH ABOUT 20Z SUNDAY BEFORE CONDITIONS SLOWLY IMPROVE. GUSTS UP TO 30 KTS AT KDEN WITH CONSIDERABLE BLOWING AND DRIFTING SNOW AND POOR VISIBILITIES CLOSE TO ONE QUARTER MILE FOR SEVERAL HOURS DURING THE HEAVIEST SNOW 11Z-20Z...THEN GRADUAL IMPROVEMENT. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM MST SUNDAY FOR COZ048- 050-051. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 5 PM MST SUNDAY FOR COZ035-036-039-040. WINTER WEATHER ADVISORY UNTIL 5 PM MST SUNDAY FOR COZ031-033-034. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 5 PM MST SUNDAY FOR COZ038-042. WINTER STORM WARNING FROM 2 AM TO 5 PM MST SUNDAY FOR COZ043-044. BLIZZARD WARNING FROM 2 AM TO 5 PM MST SUNDAY FOR COZ041-045. BLIZZARD WARNING FROM 5 AM TO 5 PM MST SUNDAY FOR COZ046-047-049. && $$ SHORT TERM...BARJENBRUCH LONG TERM....ET AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
128 PM CST SAT FEB 23 2013 .SYNOPSIS... ISSUED AT 519 AM CST SAT FEB 23 2013 06Z SFC ANALYSIS HAS AN OCCLUDED LOW NEARING THE MACKINAC STRAITS WHILE HIGH PRESSURE WAS ACROSS THE PLAINS. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS THE PLAINS WITH 20S AND 30S ACROSS THE GREAT LAKES AND OHIO VALLEY. && .UPDATE... ISSUED AT 127 PM CST SAT FEB 23 2013 WITH THE CLEARING OF THE CLOUDS HAVE BOOSTED MAX TEMPS A LITTLE...ESPECIALLY ACROSS THE WESTERN HALF OF THE AREA WHERE SUNSHINE HAS BEEN OUT THE LONGEST. WITH THE CLEARING OF THESE LOW CLOUDS THERE IS A NEW CONCERN FOR TONIGHT. WILL BE LOOKING AT HOW MUCH COLDER TO GO WITH MIN TEMPS...BUT HAVE NOT MADE ANY ADJUSTMENTS YET. HOWEVER...THIS DOES RAISE THE SPECTER OF FOG AS WE SAW LAST NIGHT OVER EASTERN NEBRASKA. THUS...HAVE PUT IN AREAS OF FOG FOR TONIGHT AND EARLY SUNDAY. LIKELY THE FOG WILL BE ACCOMPANIED BY LOW CLOUDS AS WELL...BUT WILL ALSO REVISIT THIS THIS AFTERNOON. LE && .SHORT TERM...TODAY AND TONIGHT ISSUED AT 519 AM CST SAT FEB 23 2013 A COMBINATION OF CYCLONIC FLOW ALOFT AND VORT MAXES...MAINLY AT 700 MB IS PRODUCING FLURRIES/LIGHT SNOW ACROSS THE NORTHERN PART OF THE CWFA AND UP INTO MINNESOTA. THE RAP TRENDS HAVE THE 700MB SHORTWAVE ROTATING THROUGH DURING THE DAY WITH NEAR CONTINUOUS 700MB VORT MAXES ROTATING THROUGH. THUS FLURRIES/VERY LIGHT SNOW WILL BE SEEN ACROSS ROUGHLY THE NORTHERN HALF DURING THE MORNING. FCST SOUNDINGS SHOW A DRYING ALOFT OCCURRING DURING THE AFTERNOON SO ANY FLURRIES/LIGHT SNOW WILL GRADUALLY END. BASED ON 0.5KM CONDENSATION PRESSURES/WIND...CLOUDS SHOULD STAY PUT FOR MUCH OF THE MORNING BEFORE CLEARING STARTS FROM WEST TO EAST DURING THE AFTERNOON. THE COLD POOL ALOFT MAY HELP GENERATE SOME DIURNAL CLOUDS WHICH MAY SLOW THE RATE OF CLEARING DURING THE AFTERNOON HOURS. ..08.. .LONG TERM...SUNDAY THROUGH NEXT FRIDAY ISSUED AT 519 AM CST SAT FEB 23 2013 THE EXTENDED STORM IS IN MUCH BETTER AGREEMENT IN MODEL FORECASTS TONIGHT...AND IS FOCUSED ON A SURFACE LOW TRACK FROM OK/AR THROUGH INDIANA MONDAY INTO TUESDAY. THE STORM SHOULD ONCE AGAIN HAVE A BROAD UPPER LOW ASSOCIATED WITH IT...AND BY IN LARGE...THE UPPER LOW SHOULD DOMINATE THE AREAL PLACEMENT OF RAIN AND SNOW. THE BIGGEST DIFFERENCE IN MODELS TONIGHT...IS THAT NO MODEL FORECASTS AN INTENSIFYING SURFACE LOW...OR EVEN A STRONG OCCLUDED LOW AS IT MOVES PAST THE REGION. THIS WOULD INDICATE A MUCH LOWER RISK FOR A STRONG WIND DRIVEN SNOW/BLIZZARD THAN THE EARLIER 12Z ECMWF WOULD HAVE INDICATED. DESPITE THIS...THE STORM SHOULD BE ABLE TO PRODUCE A HEALTHY DEFORMATION ZONE...AND ALL MODELS BRUSH THIS FORCING THROUGH THE CENTRAL AND SOUTHERN CWA...AND THIS MAY REQUIRE HEADLINES TO BE ISSUED TODAY IN OUR SOUTH. MODERATE SNOW ACCUMULATIONS OVER 3 INCHES SEEM LIKELY WITH THIS SYSTEM...AND SHOULD A DIRECT HIT FROM THE DEF ZONE OCCUR...HEAVY AMOUNTS ARE POSSIBLE. AS THE SYSTEM MOVES PAST INTO THE LOWER GREAT LAKES...MORE ENERGY IS FORECAST BY THE GFS AND ECMWF TO MOVE INTO THE WESTERN SIDE OF THE UPPER LOW...AND THIS SHOULD PRODUCE AN EXTENDED PERIOD OF LIGHT SNOW BEGINNING TUESDAY NIGHT INTO WEDNESDAY NIGHT. THE GFS IS MOST BULLISH...WITH 1 TO 2 INCHES OF SNOW FOR SEVERAL PERIODS IN A ROW FOR A LARGE AREA...WHILE THE ECMWF IS MORE CONSERVATIVE. ANY WAY YOU SHAKE IT...IT APPEARS UNSETTLED...CLOUDY...WITH LIGHT SNOW OR FLURRIES IN THE WAKE OF THE EARLY WEEK STORM...AT LEAST THROUGH WEDNESDAY NIGHT. LATE WEEK...MODELS SHOW A MUDDLED MESS OF NORTHERLY FLOW ALOFT. THERE CERTAINLY COULD BE SOME SNOW POTENTIAL THERE...BUT IF IT WOULD OCCUR...MOISTURE WOULD BE VERY LIMITED...AND AMOUNTS VERY LIGHT. TEMPERATURES WILL AGAIN BE FORECAST TO AVERAGE BELOW NORMAL ON HIGHS...MAINLY IN THE LOWER TO MID 30S THIS WEEK. LOWS IN THE TEENS TO MID 20S ARE FORECAST FROM NORTHWEST TO SOUTHEAST...WITH THE MILDEST LOWS ASSOCIATED WITH MONDAY NIGHT AND TUESDAY NIGHT AS WE SHOULD EXPERIENCE HIGHER DEWPOINTS WITH THE POTENTIAL SNOW EVENT. ERVIN && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1142 AM CST SAT FEB 23 2013 MVFR CIGS GRADUALLY CLEARING THE TERMINALS FROM WEST TO EAST...AND SHOULD CLEAR NO LATER THAN 19Z. KDBQ WILL REMAIN NEAR THE EDGE AND MAY FLIRT WITH BKN015 FOR THE NEXT SEVERAL HOURS...AND WILL HAVE TO CLOSELY MONITOR. THESE CLEAR SKIES TO ALLOW FOG AND STRATUS TO DEVELOP LATE TONIGHT AS WARM AIR BEGINS TO ADVECT OVER THE TOP OF THIS FRESH SNOW. HAVE GONE WITH MAINLY IFR CONDITIONS GENERALLY FROM 09Z TO 15Z...THOUGH LIFR IS POSSIBLE AT KCID WHERE IT WILL BE CLEAR THE LONGEST. VISIBILITIES TO REMAIN MVFR AT KDBQ AND KMLI AS EXPECT STRATUS TO SET IN FIRST. LE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...LE SYNOPSIS...08 SHORT TERM...08 LONG TERM...ERVIN AVIATION...LE
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1142 AM CST SAT FEB 23 2013 .SYNOPSIS... ISSUED AT 519 AM CST SAT FEB 23 2013 06Z SFC ANALYSIS HAS AN OCCLUDED LOW NEARING THE MACKINAC STRAITS WHILE HIGH PRESSURE WAS ACROSS THE PLAINS. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS ACROSS THE PLAINS WITH 20S AND 30S ACROSS THE GREAT LAKES AND OHIO VALLEY. && .SHORT TERM...TODAY AND TONIGHT ISSUED AT 519 AM CST SAT FEB 23 2013 A COMBINATION OF CYCLONIC FLOW ALOFT AND VORT MAXES...MAINLY AT 700 MB IS PRODUCING FLURRIES/LIGHT SNOW ACROSS THE NORTHERN PART OF THE CWFA AND UP INTO MINNESOTA. THE RAP TRENDS HAVE THE 700MB SHORTWAVE ROTATING THROUGH DURING THE DAY WITH NEAR CONTINUOUS 700MB VORT MAXES ROTATING THROUGH. THUS FLURRIES/VERY LIGHT SNOW WILL BE SEEN ACROSS ROUGHLY THE NORTHERN HALF DURING THE MORNING. FCST SOUNDINGS SHOW A DRYING ALOFT OCCURRING DURING THE AFTERNOON SO ANY FLURRIES/LIGHT SNOW WILL GRADUALLY END. BASED ON 0.5KM CONDENSATION PRESSURES/WIND...CLOUDS SHOULD STAY PUT FOR MUCH OF THE MORNING BEFORE CLEARING STARTS FROM WEST TO EAST DURING THE AFTERNOON. THE COLD POOL ALOFT MAY HELP GENERATE SOME DIURNAL CLOUDS WHICH MAY SLOW THE RATE OF CLEARING DURING THE AFTERNOON HOURS. ..08.. .LONG TERM...SUNDAY THROUGH NEXT FRIDAY ISSUED AT 519 AM CST SAT FEB 23 2013 THE EXTENDED STORM IS IN MUCH BETTER AGREEMENT IN MODEL FORECASTS TONIGHT...AND IS FOCUSED ON A SURFACE LOW TRACK FROM OK/AR THROUGH INDIANA MONDAY INTO TUESDAY. THE STORM SHOULD ONCE AGAIN HAVE A BROAD UPPER LOW ASSOCIATED WITH IT...AND BY IN LARGE...THE UPPER LOW SHOULD DOMINATE THE AREAL PLACEMENT OF RAIN AND SNOW. THE BIGGEST DIFFERENCE IN MODELS TONIGHT...IS THAT NO MODEL FORECASTS AN INTENSIFYING SURFACE LOW...OR EVEN A STRONG OCCLUDED LOW AS IT MOVES PAST THE REGION. THIS WOULD INDICATE A MUCH LOWER RISK FOR A STRONG WIND DRIVEN SNOW/BLIZZARD THAN THE EARLIER 12Z ECMWF WOULD HAVE INDICATED. DESPITE THIS...THE STORM SHOULD BE ABLE TO PRODUCE A HEALTHY DEFORMATION ZONE...AND ALL MODELS BRUSH THIS FORCING THROUGH THE CENTRAL AND SOUTHERN CWA...AND THIS MAY REQUIRE HEADLINES TO BE ISSUED TODAY IN OUR SOUTH. MODERATE SNOW ACCUMULATIONS OVER 3 INCHES SEEM LIKELY WITH THIS SYSTEM...AND SHOULD A DIRECT HIT FROM THE DEF ZONE OCCUR...HEAVY AMOUNTS ARE POSSIBLE. AS THE SYSTEM MOVES PAST INTO THE LOWER GREAT LAKES...MORE ENERGY IS FORECAST BY THE GFS AND ECMWF TO MOVE INTO THE WESTERN SIDE OF THE UPPER LOW...AND THIS SHOULD PRODUCE AN EXTENDED PERIOD OF LIGHT SNOW BEGINNING TUESDAY NIGHT INTO WEDNESDAY NIGHT. THE GFS IS MOST BULLISH...WITH 1 TO 2 INCHES OF SNOW FOR SEVERAL PERIODS IN A ROW FOR A LARGE AREA...WHILE THE ECMWF IS MORE CONSERVATIVE. ANY WAY YOU SHAKE IT...IT APPEARS UNSETTLED...CLOUDY...WITH LIGHT SNOW OR FLURRIES IN THE WAKE OF THE EARLY WEEK STORM...AT LEAST THROUGH WEDNESDAY NIGHT. LATE WEEK...MODELS SHOW A MUDDLED MESS OF NORTHERLY FLOW ALOFT. THERE CERTAINLY COULD BE SOME SNOW POTENTIAL THERE...BUT IF IT WOULD OCCUR...MOISTURE WOULD BE VERY LIMITED...AND AMOUNTS VERY LIGHT. TEMPERATURES WILL AGAIN BE FORECAST TO AVERAGE BELOW NORMAL ON HIGHS...MAINLY IN THE LOWER TO MID 30S THIS WEEK. LOWS IN THE TEENS TO MID 20S ARE FORECAST FROM NORTHWEST TO SOUTHEAST...WITH THE MILDEST LOWS ASSOCIATED WITH MONDAY NIGHT AND TUESDAY NIGHT AS WE SHOULD EXPERIENCE HIGHER DEWPOINTS WITH THE POTENTIAL SNOW EVENT. ERVIN && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1142 AM CST SAT FEB 23 2013 MVFR CIGS GRADUALLY CLEARING THE TERMINALS FROM WEST TO EAST...AND SHOULD CLEAR NO LATER THAN 19Z. KDBQ WILL REMAIN NEAR THE EDGE AND MAY FLIRT WITH BKN015 FOR THE NEXT SEVERAL HOURS...AND WILL HAVE TO CLOSELY MONITOR. THESE CLEAR SKIES TO ALLOW FOG AND STRATUS TO DEVELOP LATE TONIGHT AS WARM AIR BEGINS TO ADVECT OVER THE TOP OF THIS FRESH SNOW. HAVE GONE WITH MAINLY IFR CONDITIONS GENERALLY FROM 09Z TO 15Z...THOUGH LIFR IS POSSIBLE AT KCID WHERE IT WILL BE CLEAR THE LONGEST. VISIBILITIES TO REMAIN MVFR AT KDBQ AND KMLI AS EXPECT STRATUS TO SET IN FIRST. LE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...08 SHORT TERM...08 LONG TERM...ERVIN AVIATION...LE
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
938 AM MST SAT FEB 23 2013 .SHORT TERM...VALID FOR TDY AND SUN... AREA OF SNOW THIS MORNING OVER THE WESTERN ZONES WITH SOME SNOW SHOWERS EAST OF BILLINGS BUT RADAR SEEMS TO BE REFLECTING MORE MELTING LAYER ACTIVITY THAN ACTUAL SNOWFALL. SNOWFALL LOOKS TO BE INTENSE FOR ABOUT A HALF HOUR BEFORE DECREASING...SO UPDATED CURRENT FORECAST TO NUDGE UP AMOUNTS OVER THE SOUTHWESTERN ZONES A BIT. SNOWFALL SHOULD BECOME A BIT MORE PERSISTENT SOUTH OF BILLINGS THIS AFTERNOON AS DIGGING SYSTEM OVER IDAHO CAUSES A FRONTAL BOUNDARY TO BEGIN SLOWING. FRONT SHOULD REACH BILLINGS AROUND NOON BUT STILL COULD SEE A COUPLE OF DEGREES OF WARMING BETWEEN NOW AND THEN SO DID NOT LOWER TEMPERATURES. MOST PRECIPITATION WILL FALL AS SNOW ESPECIALLY WITH DEWPOINT DEPRESSIONS AROUND 20 DEGREES...BUT RADAR DOES INDICATE SOME MELTING MAY BE GOING ON. UPDATE SENT. BORSUM PREVIOUS DISCUSSION...ISSUED AT 308 AM MST SAT FEB 23 2013... PASSAGE OF A 500-HPA SHORT WAVE TROUGH AND SURFACE COLD FRONT WILL BRING SNOW SHOWER CHANCES TO THE FOREFRONT TODAY. MOISTURE CHANNEL IMAGERY AT 10 UTC SHOWS THAT TROUGH AXIS ENTERING WESTERN ID...AND THAT IS STARTING TO DISRUPT THE ENVIRONMENT NEEDED FOR NOTABLE GAP WINDS. THAT PROCESS SHOULD BE COMPLETE BETWEEN 12 AND 15 UTC...BUT IN THE INTERIM WE WILL LET OUR WIND ADVISORY AT LIVINGSTON AND NYE RIDE FOR A FEW MORE HOURS. TODAY AND TONIGHT...WE HAVE POPS IN THE 60 TO 90 PERCENT RANGE FOR 1/ THE LIVINGSTON...BIG TIMBER...AND COOKE CITY AREAS UNTIL 18 UTC AND 2/ THE LODGE GRASS...SHERIDAN...AND EVEN BROADUS AREAS BETWEEN 18 AND 06 UTC. THOSE LIKELY AND CATEGORICAL POPS ARE LINED UP WITH THE MOST GENEROUS SYNOPTIC-SCALE FORCING WITH THE SHORT WAVE ALOFT AND THE EXIT REGION OF A WEAKENING 300-HPA JET STREAK WHICH THE 00 UTC GUIDANCE SHOWS SINKING SOUTHWARD TODAY. WE HAVE CHANCE POPS IN MOST OTHER PLACES DURING THE DAY...INCLUDING BILLINGS...BUT DIDN/T GO ANY HIGHER IN ORDER TO CONVEY THE MORE SCATTERED OR SHORT-LIVED NATURE OF SHOWERS OUTSIDE OF THE BETTER FORCING. SNOW IS MENTIONED AS THE PREDOMINATE PRECIPITATION TYPE FOR MOST OF THE AREA BECAUSE THAT NOTION HAS STRONG SUPPORT FROM GFS/ECMWF/NAM WET BULB HEIGHTS AND NCEP PRECIPITATION-TYPE ALGORITHMS APPLIED TO THE 21 UTC SREF. WHERE IMPACTS ARE CONCERNED...OUR MAIN CONCERN IS FOR SHERIDAN AND MAYBE EVEN SOUTHERN BIG HORN COUNTY...WHERE THERE IS SOME RISK OF ADVISORY-LEVEL SNOWFALL THIS AFTERNOON AND EVENING. THE 00 UTC GFS AND RECENT RUNS OF THE RAP /WHICH GETS LATERAL BOUNDARY CONDITIONS FROM THE GFS/ ARE THE MOST AGGRESSIVE QPF SOLUTIONS FOR THAT AREA. HOWEVER...SINCE THOSE QPF NUMBERS ARE HIGHER THAN MOST OF THE REST OF THE PACK...AND BECAUSE IT IS NOT CLEAR HOW EFFICIENT UPSLOPE IN THE LOW LEVELS WILL BE...WE CHOSE TO KEEP SNOW AMOUNTS IN THE 1 TO 3 INCH RANGE /JUST BELOW ADVISORY CRITERIA/ FOR NOW. THIS COULD BE A CASE WHERE NEAR TERM OBSERVATIONAL TRENDS GIVE ENOUGH CONFIDENCE FOR US TO HOIST A HEADLINE LATER TODAY IF GFS-BASED SOLUTIONS WIND UP BEING CORRECT. THE 06 UTC GFS HAS TRENDED EVEN HIGHER WITH ITS QPF...SO THIS SITUATION BEARS CLOSE WATCHING. SUN...NORTH-NORTHWEST FLOW WILL BE IN PLACE ALOFT WITH BOTH MODEST DRYING AND WARMING IN THE LOW- AND MID-LEVELS. WE DECIDED TO LEAVE OUR GOING FORECAST ALONE FOR NOW SINCE IT SHOWS POPS MAINLY BEFORE 18 UTC...WHEN FLOW IS MORE CYCLONIC. HOWEVER...BOTH THE 00 UTC GFS AND NAM SHOW A DECENT BATCH OF 500-300 HPA Q-VECTOR CONVERGENCE IN THE 18 TO 00 UTC TIME FRAME...WHICH MAKES US WONDER IF THERE COULD BE SOME CONVECTION DURING THE AFTERNOON. THAT WILL BE SOMETHING TO CONSIDER WITH LATER FORECAST RELEASES. OTHERWISE...WE DID INCREASE HIGHS USING THE 00 UTC BIAS-CORRECTED MULTI-MODEL CONSENSUS /WHICH HAS VERIFIED WELL LATELY/...AND WINDS ON SUN NIGHT NEAR LIVINGSTON AND BIG TIMBER AS SURFACE PRESSURE FALLS BEGIN ACROSS THE NORTHERN ROCKIES AGAIN. SCHULTZ .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MODELS IN PRETTY GOOD AGREEMENT THROUGH WEDNESDAY. SMALL SYSTEM FOR THURSDAY SHOWS SOME SIGNS OF GETTING BETTER ORGANIZED IN THE GFS BUT NOT SO MUCH IN THE EUROPEAN MODEL. STRONG RIDGING AND MUCH WARMER TEMPERATURES LOOK TO BE ON TRACK FOR NEXT WEEKEND. BRIEF RIDGING BEHIND SUNDAY SYSTEM SHOULD BRING PARTLY CLOUDY AND DRY CONDITIONS TO THE FIRST HALF OF MONDAY. BY LATE IN THE DAY NEXT SYSTEM UPSTREAM QUICKLY BUILDS INTO THE AREA WITH INCREASING PRECIPITATION CHANCES THROUGH TUESDAY. SOME WEAK ENERGY LINGERS INTO WEDNESDAY OVER SOUTHERN ZONES BUT BY WEDNESDAY AFTERNOON RIDGING DEVELOPS ENDING PRECIPITATION CHANCES. GFS BRINGS NEXT SYSTEM INTO IDAHO WEDNESDAY NIGHT AND SEEMS TO BE TRYING TO CUT OFF UPPER LOW NEAR WEST YELLOWSTONE THURSDAY MORNING. ECMWF DIGS THIS SAME TROF MUCH FURTHER SOUTH AND SPLITS THE SYSTEM OVER THE AREA RESULTING IN SOME CLOUD COVER BUT LITTLE IN THE WAY OF PRECIPITATION OUTSIDE OF MOUNTAIN AREAS. CAUSE OF THE DIFFERENCES IS DUE TO HANDLING OF STRONG DOWNSTREAM SYSTEM OVER THE EASTERN US...AND CURRENT GUIDANCE FAVORS THE EC SOLUTION SO LEFT FORECAST DRY AND WARMED TEMPERATURES JUST A BIT. ALL THE MODELS IN GOOD AGREEMENT WITH DEVELOPMENT OF STRONG RIDGING FRIDAY THROUGH NEXT WEEKEND. BOTH MODELS SHOW SATURDAY 850 TEMPERATURES IN THE +6 TO +10C RANGE LEADING TO MIX DOWN TEMPERATURES WELL INTO THE 50S FOR HIGHS FRIDAY THROUGH SUNDAY. NOT OUT OF THE QUESTION TO SEE SOME LOWER 60S SATURDAY AND SUNDAY WITH DRY CONDITIONS UNDER THE RIDGE. CHAMBERS && .AVIATION... SCATTERED SNOW SHOWERS ARE DEVELOPING ACROSS THE AREA AS THE COLD FRONT MOVES THROUGH. MAINLY VFR CONDITIONS WILL PREVAIL IN MOST AREAS WITH LOWER CONDITIONS IN AND AROUND NEAR SNOW SHOWERS. VLIFR CONDITIONS HAVE BEEN REPORTED IN KLVM THIS MORNING...WITH LOW CIGS AND VIS. FOOTHILLS AND MOUNTAIN AREAS WILL SEE MAINLY MVFR CONDITIONS WITH LOCAL IFR OR LOWER CONDITIONS WITH HEAVIER SNOW SHOWERS. MOUNTAIN AND PASS OBSCURATION WILL EXIST FOR ALL AREA MOUNTAINS THROUGH TONIGHT. AAG && .PRELIMINARY POINT TEMP/POPS... TDY SUN MON TUE WED THU FRI ------------------------------------------------------- BIL 041 025/041 022/039 024/037 021/037 023/045 026/051 4/W 32/J 11/B 33/J 11/U 32/J 00/B LVM 039 020/035 016/035 019/032 013/033 017/038 025/044 8/W 33/W 12/J 44/J 11/U 32/J 11/B HDN 042 023/043 019/037 022/036 017/035 020/043 023/049 5/W 43/J 11/B 34/J 21/U 33/J 10/B MLS 044 027/042 021/037 022/036 020/035 020/041 024/047 2/W 22/J 11/U 23/J 21/B 12/J 10/B 4BQ 041 024/038 017/035 020/033 018/032 017/039 020/045 6/W 73/J 11/U 24/J 21/B 12/J 10/B BHK 041 024/035 016/032 019/031 018/031 016/036 018/040 3/W 22/J 11/U 13/J 21/B 11/B 10/B SHR 038 020/036 012/034 018/032 015/033 016/039 018/045 8/J 83/J 11/U 44/J 21/U 22/J 10/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1252 PM EST SAT FEB 23 2013 .SYNOPSIS... A COMBINATION OF TWO STORM SYSTEMS...ONE TO OUR NORTHWEST AND ANOTHER MOVING UP THE COAST...WILL BRING US UNSETTLED WEATHER TODAY WITH PLENTY OF CLOUDS. MOST OF THE AREA WILL SEE RAIN DEVELOP BY AFTERNOON...BUT SOME WET SNOW IS POSSIBLE ACROSS ONEIDA COUNTY AND THE CATSKILLS. BY TONIGHT AS COLDER AIR MOVES BACK INTO OUR AREA...A PERIOD OF FREEZING RAIN IS POSSIBLE OVER THE CATSKILLS...WITH A GRADUAL TRANSITION FROM RAIN TO SNOW OVER THE ENTIRE AREA BEFORE ENDING. LIGHT SNOW SHOWERS ARE POSSIBLE SUNDAY IN CENTRAL NY WITH DRIER WEATHER BY MONDAY. && .NEAR TERM /THROUGH TONIGHT/... 930 AM UPDATE... CONVOLUTED FCST WITH CWA RMNG IN VRY WK FORCING AND PCPN POPPING UP AT RANDOM ACRS THE AREA, THO MOST IS CONFINED CLOSER TO H5-H7 LIFT IN THE FINGER LKS REGION. 12Z RAOBS FM KBUF AND KALY SHOWING VRY LITTLE ICE IN THE CLD, IN AGREEMENT WITH FCST SNDGS FM BUFKIT. MOST OBS ACRS THE AREA ARE REPORTING SOME FORM OF LIQUID THUS HV TWEAKED WX GRIDS TO GO RAIN OR DRIZZLE EXCEPT WHERE LOCALES ARE BLO FZG AND HV ADDED IN A FRZG MENTION. MOISTURE RETURNS IN THE -10C TO -20C LAYER AFTR ABOUT 18Z THIS AFTN AND HV ADDED IN SNOW/FLURRY MENTION BACK IN. BEST CHC FOR SNOW LOOKS TO BE ACRS NRN ONEIDA CNTY LATE THIS AFTN WITH STRONG CONVERGENCE BRINGING A QUICK 1-2 INCHES LATE TDA. ELSEWHERE IT LOOKS TO BE A WINTRY MESS FOR MOST OF THE DAY. LATEST NAM12 HAS COME IN WITH CURRENT SFC LOW LOCATED OFF OF VA/NC BORDER RMNG SOUTH OF OUR AREA TONIGHT AND VRY MINIMAL QPF SPREADING INTO SERN PARTS OF CWA THRU TONIGHT. ONSHORE FLOW WL BE POSSIBLE WITH CHC CONTG FOR LGT PCPN BUT WL IT BE IN THE FORM OF LGT FZRA OR FZDZ. WL AWAIT ADDNL 12Z GUIDANCE BFR MAKING DECISION ON WHAT TO DO WITH EXISTING ADVISORY FOR TONIGHT, WHETHER IT BE TO TWEAK THE AREA OR CANCEL IT ALTOGETHER. ONLY MINOR TWEAKS MADE TO HRLY T/TD GRIDS AT THIS TIME. 6 AM UPDATE... THIS MORNING...AN AREA OF PRECIPITATION MAINLY FROM THE NY/PA LINE NORTH THROUGH THE FINGER LAKES CONTINUES TO MOVE THROUGH OUR AREA. OVER THE PAST 2 HOURS THE INTENSITY ON RADAR OF THIS PRECIP HAS INCREASED. THIS IS LIKELY DUE TO SOME SLEET MIXING IN AS EVIDENT BY LOWER VALUES OF CC ON THE DUAL POL PRODUCTS. THIS IS INDICATING MIXED HYDROMETEORS AND BASED ON SOUNDINGS AND THIS AREA COINCIDING WITH HIGHER RETURNS...SLEET IS THE MOST LIKELY P-TYPE HERE. THE LATEST RUC SEEMS TO OFFER THE BEST HOPE FOR A SHORT TERM FORECAST BASED ON A LOBE OF VORTICITY AT 500 MB MOVING THROUGH...THAT LINES UP WELL WITH THE PRECIP. THE RUC MOVES THIS OFF TO THE NORTHEAST BY 12Z. BASED ON RADAR TRENDS THOUGH MAY SLOW THIS DOWN A TAD. PRECIP INTENSITY WILL BE RELATIVELY LIGHT AS WILL QPF AMOUNTS. WE ARE LACKING ICE IN THE CLOUD SO P-TYPE LOOKS TO BE MAINLY RAIN OR SOME ICE PELLETS EXCEPT ACROSS THE FAR NORTH AND EAST WHERE SLIGHTLY DEEPER MOISTURE PROFILES ALLOW FOR SOME SNOW. ISOLATED POCKETS OF FREEZING RAIN ARE POSSIBLE BUT IT APPEARS WHERE THE LIQUID PRECIP IS MOST LIKELY...TEMPS ARE ALREADY NEAR OR ABOVE FREEZING. WHERE WE HAVE COLDER SURFACE TEMPS...MOISTURE ALOFT SUPPORTS MORE SNOW. AFTER THIS MOVES THROUGH WE MAY SEE A LULL FOR A FEW HOURS FOR MOST OF US. LATER THIS MORNING/TONIGHT...NEXT FEATURES OF INTEREST WILL BE AN AREA OF LOW PRESSURE MOVING THROUGH THE GREAT LAKES AND AN AREA OF LOW PRESSURE NOW TAKING SHAPE OFF THE CAROLINA COAST. OUR AREA WILL BE IN ON THE SQUEEZE PLAY TODAY WITH INCREASING MOISTURE FROM BOTH THE WEST (GREAT LAKES SYSTEM) AND EAST (COASTAL SYSTEM). MAIN ADJUSTMENT WAS TO TRIM BACK POPS IN THE MIDDLE TODAY...AND PUSH BACK THE BEST SHOT AT WIDESPREAD PRECIPITATION INTO THE 18Z - 22Z RANGE. OVERALL THOUGH LOOKING AT A FAIRLY LIGHT QPF EVENT WITH AROUND AMOUNTS RANGING FROM A TENTH TO TWO TENTHS. THE FIRST TRIGGER FOR PRECIP WILL COME BY LATE MORNING AS A RIBBON OF PVA SLIDES INTO WESTERN NY...IN THE FLOW AROUND THE PARENT UPPER LOW OVER THE GREAT LAKES. THIS WILL MOVE ACROSS THE REST OF THE AREA TOWARD 20Z...AS WE ALSO GETTING INCREASING UPPER LEVEL LIFT OVER THE FAR SOUTHEAST IN RESPONSE TO THE COASTAL LOW. I RAMP POPS UP GREATLY IN THE 22Z TO 0Z PERIOD TO SHOW OUR BEST SHOT AT PRECIPITATION ACROSS MOST OF THE AREA AS THIS HAPPENS. AS FAR AS P-TYPE GOES...A TONGUE OF WARMER AIR AROUND 800 MB WILL KEEP US MOSTLY RAIN THROUGH LATE THIS AFTERNOON. THE EXCEPTION WILL BE ACROSS NORTHERN ONEIDA COUNTY WHERE TEMPS ALOFT NEVER GET ABOVE 0C...SO AT THE VERY LEAST A RAIN/SNOW MIX IS LIKELY IF NOT MOSTLY SNOW...ALL DAY. WE COULD SEE UP TO 2 INCHES HERE THROUGH AFTERNOON ACROSS THE HIGHER TERRAIN. OVER THE FAR EAST SNOW IS POSSIBLE EARLY BUT EVEN HERE TEMPS ALOFT WARM UP ABOVE 0C AFTER 21Z. DURING THIS TIME SOME AREAS OF FREEZING RAIN ARE POSSIBLE IN OUR NORMALLY COLDEST SECTIONS...WITH PLAIN RAIN OR A FEW SLEET PELLETS POSSIBLE ELSEWHERE. TONIGHT...AS THE COASTAL SYSTEM DEEPENS AND MOVES WELL OUT TO SEA...COLDER AIR ALOFT WILL RAPIDLY MOVE IN FROM THE WEST. THIS WILL CHANGE OUR RAIN OVER TO A PERIOD OF LIGHT SNOW BEFORE ENDING OVERNIGHT. ACCUMS EXPECTED TO BE AROUND AN INCH OR LESS. THE TRICKY SPOT WILL BE ROUGHLY FROM DELAWARE COUNTY SOUTH THROUGH WAYNE AND PIKE COUNTIES...WHERE TEMPS ALOFT WILL REMAIN ABOVE 0C THROUGH 03Z THIS EVENING. NAM SOUNDINGS HAVE REMAINED CONSISTENT SINCE LAST NIGHT SHOWING SOME BOUNDARY LAYER COOLING DURING THIS TIME ALLOWING SURFACE TEMPS TO BE NEAR OR SLIGHTLY BELOW FREEZING. GFS PROFILES COULD NOT BE MORE DIFFERENT WITH TEMPS REMAINING ABOVE FREEZING AT THE SURFACE...BEFORE A RAPID TRANSITION FROM RAIN TO SNOW...WITH NO PERIOD OF FREEZING RAIN. SREF PROFILES PROVIDE LITTLE HELP WITH SOLUTIONS SHOWING A WILD RANGE. BASED ON CLIMATOLOGY...COORDINATION WITH SURROUNDING WFOS...AND BUYING THAT THE HIGHER RESOLUTION OF THE NAM THIS CLOSE IN SHOULD BE SUPERIOR TO THE GFS...ISSUED A WINTER WEATHER ADVISORY FOR THESE AREAS. WE WANT TO STRESS THIS ADVISORY IS NOT FOR THE SNOWFALL AMOUNTS BUT FOR THE SHORT WINDOW OF TIME FROM BETWEEN 22Z THROUGH 03Z WHEN WARM TEMPS ALOFT COMBINED WITH COOLING SURFACE TEMPS WILL ALLOW FOR A PERIOD OF FREEZING RAIN. LATE TONIGHT WE HAVE PLENTY OF MOISTURE IN THE LOW LEVELS BY LACK OF MOISTURE IN THE MID LEVELS (NO ICE CRYSTALS) WILL LIKELY MEAN A FAIRLY RAPID END FROM WEST TO EAST OF ANY PRECIP. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... 600 AM UPDATE... SUNDAY/SUNDAY NIGHT...NOT MUCH CHANGE TO THE PREVIOUS FORECAST. WE REMAIN UNDER THE INFLUENCE OF THE UPPER LEVEL LOW WITH CHANCES FOR LIGHT SNOW MAINLY IN CNY BY SUNDAY AFTERNOON/NIGHT. NOT LOOKING FOR MUCH IN TERMS OF ACCUMS. && .LONG TERM /MONDAY THROUGH FRIDAY/... AN UNSETTLED PTRN FOR THE MED RNG AS LARGE UPR LVL LOW...WITH SVRL EMBEDDED IMPULSES ROTATING ARND IT...TAKES UP RESIDENCE OVER THE NE U.S.. ALL IN ALL THE HPC GDNC LOOKED GOOD BUT CHC POPS LOOKED A BIT ON THE LOW SIDE GIVEN THIS PTRN...SPCLY OVER CNTRL NY WHERE MOIST SYNOPTIC AIRMASS AND CYCLONIC FLOW WILL COMBINE WITH LAKE INFLUENCES TO ENHANCE THE SNOW SHOWERS. THIS FAR OUT...WE OPTED TO RAISE HPC CHC POP NUMBERS LATE IN THE PD AND USED "SCATTERED" TERMINOLOGY THROUGHOUT. IF MDLS REMAIN CONSISTENT...NO DOUBT WE`LL BE RAISING THE MED RNG POPS TO LIKELY FOR MUCH OF THE RGN...BUT PLENTY OF TIME FOR THAT THIS FAR OUT. PLUS WE KNOW ALL THE SUPRISES THESE CUTOFFS CAN THROW AT US. TEMPS WILL GNRLY RNG FROM THE MAXES IN THE M30S TO MINS IN THE U20S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... WDSPRD IFR/MVFR WILL PREVAIL FOR THE REMAINDER OF THE AFTN AND OVRNGT HRS...WITH CONDITIONS LIKELY TO BE BLO AIRPORT MINS AT TIMES (SPCLY AT BGM/ITH/ELM/AVP). ANY PCPN WILL BE ON THE LGT SIDE...AND PROFILES SUGGEST SHRA OR A MIX TRANSITIONING TO -SHSN TNGT AS SLIGHTLY COLDER AIR MOVS IN. XPCT MVFR TO CONTINUE AT MOST SITES INTO SUN MRNG. WINDS THIS AFTN GNRLY FROM THE SOUTH 5-10 KT...THEN VRBL BECMG WNW LATER TNGT 5-10 KTS...THEN W TO NW ON SUNDAY INCRSNG TO 10-20 KTS. .OUTLOOK... SUN NGT/MON...PATCHY MVFR CIGS CNTRL NY...OTRW VFR. MON NGT...VFR. TUE...VFR EARLY DETERIORATING TO MVFR/IFR IN MIXED PCPN. TUE NGT/WED/THU...IFR/MVFR IN SNOW AND RAIN SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST SUNDAY FOR PAZ040-048-072. NY...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST SUNDAY FOR NYZ057-062. && $$ SYNOPSIS...HEDEN NEAR TERM...HEDEN/PVN SHORT TERM...HEDEN
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1025 AM CST SAT FEB 23 2013 .DISCUSSION... CLOUDS AND TEMPS ARE THE MAIN CHALLENGE FOR TODAYS FORECAST. PRETTY CONSISTENT CLOUD BAND JUST TO THE EAST OF THE RED RIVER VALLEY WITH LOTS OF SUN TO THE WEST. THERE ARE ALSO SOME HOLES IN THE CLOUDS DOWN NEAR KAXN AND UP BY KINL. SFC FEATURES ARE EVIDENT ON THE VISIBLE SATELLITE IMAGERY THROUGH THE CLOUDS EAST OF THE VALLEY. HOWEVER THERE IS VERY WEAK WIND FLOW SO THE MAIN QUESTION WILL BE THE POWER OF THE LATE FEBRUARY SUN. THERE ARE SOME HINTS OF EROSION ON THE WESTERN FRINGE OF THE MAIN CLOUD BAND AND WITH THE HOLES APPEARING ALREADY IN THE PREVIOUSLY MENTIONED AREAS THINK THERE MAY BE A SHOT AT CLEARING IN THE IMMEDIATE RED RIVER VALLEY AND FOR THE LAKE OF THE WOODS REGION. OTHER AREAS FROM KDTL TO KROX MAY BE A TOUGHER CALL AND WILL JUST HAVE TO SEE HOW THINGS PAN OUT. LOTS OF FOG OUT THERE NOW BUT VSBYS HAVE MOSTLY RISEN ENOUGH TO LEAVE ANY MENTION OF IT OUT FOR THE AFTERNOON. && .AVIATION... AS WITH THE ABOVE REASONING WILL JUST HAVE TO MONITOR THE TAF SITES THRU THE REST OF THE MORNING TO SEE IF ANY TRENDS CAN BE ESTABLISHED. && .PREV DISCUSSION... /ISSUED 326 AM CST SAT FEB 23 2013/ SHORT TERM (TODAY-MONDAY NIGHT)... INITIALLY CLOUDS AND FOG WILL BE THE CONCERN. OTHERWISE...CLOUDS AND LIGHT SNOW CHANCES WILL BE THE CHALLENGE. 00Z MODELS IN DECENT AGREEMENT ALTHOUGH WITH DETAIL DIFFERENCES SUNDAY INTO MONDAY. WILL USE A BLEND FOR THIS FORECAST. THE FORECAST AREA (FA) IS CURRENTLY STUCK WITHIN A VERY WEAK FLOW ENVIRONMENT. LOW CLOUDS EXIST ALONG AND EAST OF THE VALLEY. THESE CLOUDS SEEM TO BE OCCURRING WHERE MODELS SHOW 925MB WINDS CALM TO 5 KNOTS. WILL USE THE RAP AS GUIDANCE FOR WHEN SKIES WILL CLEAR FROM WEST TO EAST (AS LOW LEVEL FLOW INCREASES). THIS SLOWS THE CLEARING TREND TODAY. PATCHY DENSE FOG HAS OCCURRED WITHIN THIS WEAK FLOW ENVIRONMENT...BUT 1/4SM VSBY HAS NOT BEEN CONSISTENT FROM HOUR TO HOUR. WILL KEEP PATCHY FOG IN THE GRIDS THROUGH THE MORNING HOURS WHERE CLOUDS (WEAK MIXING) IS EXPECTED...AND MONITOR FOG CONDITIONS. FOR SUNDAY INTO MONDAY...SOUTHERN STREAM ENERGY WILL REMAIN WELL SOUTH OF THE REGION...BUT THERE WILL BE A WEAK NORTHERN STREAM WAVE THAT AFFECTS THE REGION DURING THIS TIME. THE ECMWF IS STRONGER WITH THE RIDGING TO THE EAST...AND KEEPS THIS FEATURE WEST OF OTHER MODELS (WESTERN DAKOTAS VS EASTERN DAKOTAS) AS IT DROPS TO THE SOUTH AND INTO THE SOUTHERN STREAM WAVE. THE MAIN AFFECT OF THIS WAVE WILL LIKELY BE CLOUD COVER...BUT LIGHT SNOW IS ALSO POSSIBLE. THE EXACT LOCATION OF THIS WAVE WILL DETERMINE WHERE/WHEN THE LIGHT SNOW OCCURS. IF THE ECMWF IS CORRECT ACCUMULATIONS WILL BE MAYBE A DUSTING...AND IF THE OTHER MODELS ARE CORRECT ACCUMULATIONS COULD BE AN INCH OR TWO. WILL MAINTAIN PREVIOUS FORECAST OF LOW POPS ACROSS THE WESTERN FA WITH ONLY A DUSTING POSSIBLE (AS PMDHMD PREFERS THE ECMWF). LONG TERM (TUESDAY-FRIDAY)... MODELS CONTINUE TO BE IN FAIR AGREEMENT WITH A QUIET WEATHER PATTERN FOR THE CWFA FOR THE EXTENDED TIME FRAME WITH A SPLIT FLOW IN THE STORM TRACK. 500MB FLOW WILL TRANSITION FROM AN ARKANSAS CUTOFF LOW WITH THE NWERLY ORIENTED TROUGH THROUGH THE NORTHERN US ROCKIES INTO A POSITIVE PNA PATTERN...WESTERN RIDGE AND EASTERN TROUGH ACROSS THE CONUS...BY THE END OF THE PERIOD. WITH LITTLE UPPER LEVEL ENERGY MOVING ACROSS THE AREA ONLY SLIGHT CHC FOR POPS WITH -SN POSSIBLE TUE AND WED ACROSS THE SOUTH AND EAST ZONES WITH TEMPS NEAR END OF FEB NORMALS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ GODON
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
255 PM CST SAT FEB 23 2013 .SHORT TERM...TONIGHT THROUGH TUESDAY 255 PM CST SAT FEB 23 2013 MAIN FORECAST CONCERNS ARE ON FREEZING FOG POTENTIAL TONIGHT AND IF AND WHEN SNOW CAN MOVE IN FOR EARLY NEXT WEEK. CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING DIGGING DOWN THROUGH THE U.S. ROCKIES... RIDGING BUILDING HEAD OF THIS TROUGH INTO THE CENTRAL PLAINS AND AN UPPER LOW ENCOMPASSING MUCH OF THE WESTERN GREAT LAKES REGION. THIS UPPER LOW COMBINED WITH MOISTURE AND WEAK SHORTWAVES ROTATING AROUND IT HAS KEPT CLOUDS IN PLACE ACROSS THE NORTHWEST HALF OF THE FORECAST AREA. 12Z GRB AND MPX SOUNDINGS REFLECT THE MOISTURE...TRAPPED BELOW A SUBSIDENCE INVERSION BETWEEN 750-800MB. THERE WERE SOME SNOW SHOWERS/FLURRIES EARLIER...BUT THESE HAVE SINCE DISSIPATED FOR THE MOST PART. TO THE WEST...CLEARING HAS BEEN WORKING INTO SOUTHWESTERN PORTIONS OF THE FORECAST AREA FROM THE PLAINS AND IOWA. 12Z ABR AND OAX SOUNDINGS SHOWED THE DRIER AIR WITH DEWPOINT DEPRESSIONS OF 5C OR MORE FROM JUST ABOVE THE SURFACE TO 300MB. AT THE SURFACE WAS A STRONG RADIATIONAL INVERSION THAT WAS SATURATED...REFLECTING THE FOG THAT OCCURRED. BOTH LOCATIONS WERE UNDER A RIDGE OF HIGH PRESSURE WHICH HAS SHIFTED EAST TO CENTRAL PORTIONS OF IOWA AND MINNESOTA. AIRMASS REMAINS COOL WITH 850MB TEMPS FROM 12Z SOUNDINGS BETWEEN -10C AND -12C...OR 1 STANDARD DEVIATION BELOW NORMAL. SHORT TERM HIGHLIGHTS/CONCERNS... TONIGHT - CLEARING/TEMPS/FOG - MODELS ARE STRUGGLING A BIT WITH THE CLEARING IMPACTING WESTERN PORTIONS OF THE FORECAST AREA. 925MB RH FIELDS FROM THE RAP/NAM/GFS WOULD ALL SUGGEST A PESSIMISTIC IDEA WITH CLOUDS HANGING AROUND MUCH OF THE NIGHT ACROSS THE FORECAST AREA. HOWEVER...AS NOTED BY SATELLITE IMAGERY...WE HAVE PARTIALLY CLEARED OUT ALREADY OVER THE SOUTHWEST HALF OF THE AREA. WITH THE SURFACE RIDGE MOVING OVER THE ENTIRE FORECAST AREA BY 12Z SUNDAY...THINKING THE CLEARING SHOULD CONTINUE TO PROGRESS EAST. THE CLEARING SKIES IN THE EVENING COMBINED WITH LIGHT WINDS...DRIER AIR MOVING IN ALOFT AND THE FRESH SNOW PACK MAKE A GREAT SITUATION FOR RADIATIONAL COOLING. WENT TOWARDS THE COLDER GFS40 2 METER TEMPERATURE GUIDANCE FOR LOWS...WHICH WAS FAIRLY SIMILAR TO THE PREVIOUS FORECAST. THE LOWS...WHICH DROP INTO THE SINGLE DIGITS ABOVE ZERO SOUTHWEST OF I-94...COMBINED WITH THE CURRENT AFTERNOON DEWPOINTS IN THE 15 TO 20 RANGE YIELD A FAVORABLE FOG AND VERY LOW STRATUS SITUATION VIA CROSS-OVER APPROACH. SREF PROBABILITIES OF LESS THAN 1 MILE SHOW A RAPID DEVELOPMENT AND EXPANSION OF FOG THROUGH THE EVENING ACROSS MINNESOTA AND IOWA...THEN SPREADING EAST INTO WISCONSIN. LATEST HRRR RUNS ARE VERY SIMILAR. GIVEN THE TEMPERATURES...FREEZING FOG WITH RIMING ON UNTREATED SURFACES WOULD OCCUR. HAVE ADDED THE FOG TO THE FORECAST...WITH THE MOST COVERAGE WEST AND SOUTH OF I-94 WHERE CONFIDENCE IS HIGHEST. IN ADDITION... AFTER COLLABORATION FROM SURROUNDING OFFICES...ISSUED A FREEZING FOG ADVISORY FOR MUCH OF THE FORECAST AREA LINING UP WITH THE GENERAL MINIMUM IN LOW TEMPS AND CLEARING AREA. IT IS POSSIBLE DENSE FOG COULD OCCUR AS WELL...BUT CONFIDENCE IS TOO LOW TO GO WITH THAT ADVISORY TYPE AT THIS TIME. IF DENSE FOG WERE TO OCCUR...ALONG AND WEST OF HIGHWAY 52 WOULD APPEAR TO HAVE THE BEST CHANCE. LATER SHIFTS MAY NEED TO REPLACE SOME OF THE FREEZING FOG ADVISORY WITH DENSE FOG IF CONFIDENCE OF GROWS. ANY FOG/STRATUS MAY TAKE SOME TIME TO MIX OUT...BUT THE HIGHER LATE FEBRUARY SUN ANGLE SHOULD ALLOW IT TO CLEAR OUT BY 18Z. MONDAY THROUGH TUESDAY - WINTER STORM COMING OUT OF THE SOUTHERN PLAINS - WHAT HAS BEEN CONSISTENT... 1. THE UPPER TROUGH RESPONSIBLE FOR THE STORM...CURRENTLY THE BASE OF THE TROUGH CROSSING THE ROCKIES...IS FORECAST TO DIG INTO TEXAS AND OKLAHOMA ON MONDAY...FARTHER SOUTH THAN THE RECENT STORM. 2. STRONG RIDGING DEVELOPS AHEAD OF UPPER TROUGH FROM THE MID-ATLANTIC TOWARDS OUR FORECAST AREA. 3. MODEL TRENDS OVERALL FROM THE GFS...CANADIAN AND ECMWF THE PAST FEW DAYS HAVE BEEN SLOWER LIFTING THE STORM OUT OF THE SOUTHERN PLAINS AND MORE TO THE SOUTHEAST...REPRESENTATIVE OF THE IMPACT THE STRONG RIDGING AHEAD OF IT IS HAVING. WHAT HAS BEEN INCONSISTENT...WHETHER THE HEAVIER BUT WEAKENING DEFORMATION BAND ON THE NORTHWEST SIDE OF THE SYSTEM WILL IMPACT PORTIONS OF THE AREA...OR STAY TO THE SOUTHEAST. TAKE FOR EXAMPLE THE 23.12Z CANADIAN...WHICH OVER THE PAST FEW DAYS HAS BEEN A SOUTHEAST SOLUTION...NOW HAS SHIFTED NORTHWEST TOWARDS THE 23.12Z GFS WHICH HAS BEEN A MORE NORTHWEST SOLUTION ALL ALONG. THE 23.12Z NAM HAS FOLLOWED SIMILARLY TO THE CANADIAN. LASTLY...THE 23.12Z ECMWF HAS SHIFTED BACK MORE NORTHWEST COMPARED TO ITS 00Z RUN. NO MATTER WHAT MODEL SOLUTION IS FOLLOWED...ANY PRECIPITATION ASSOCIATED WITH THE SYSTEM...EITHER FROM THE DEFORMATION BAND OR FROM AN INVERTED TROUGH EXTENDING NORTH FROM THE LOW...LOOKS TO HOLD OFF TO OUR WEST AND SOUTH THROUGH 12Z TUESDAY. THIS MAKES SENSE WITH THE BUILDING RIDGING ALOFT AND DRY AIR FLOW FROM HIGH PRESSURE HEADING EAST INTO THE GREAT LAKES. IN FACT...THE DRY AIR FLOW ONLY INTENSIFIES AS THE SYSTEM LIFTS NORTHEAST DUE TO THE WINDS INCREASING. THUS...HAVE A DRY FORECAST FOR MONDAY AND MONDAY NIGHT. FOR TUESDAY...FOLLOWED A CONSENSUS APPROACH ON PRECIPITATION CHANCES FOR NOW GIVEN THE MODEL INCONSISTENCIES ON THE DEFORMATION BAND. STILL...THE BEST CHANCES FOR SNOW ON TUESDAY WOULD OCCUR IN THE SOUTHEAST 1/3 OF THE AREA. AMOUNTS RIGHT NOW WOULD BE MAYBE WORTHY OF AN ADVISORY AT MOST. THE SYSTEM JUST REALLY WEAKENS AS IT LIFTS NORTHEAST AND RUNS INTO THE RIDGE. OUTSIDE OF THE SHORT TERM HIGHLIGHTS ABOVE...EXPECT THE MOST SUNSHINE TOMORROW AFTER THE MORNING FOG/STRATUS MIX OUT. AS WE HEAD INTO MONDAY AND TUESDAY...CIRRUS WILL DOMINATE THE AREA AND EVENTUALLY LOWER CLOUDS COME TUESDAY. DESPITE THE HIGH CLOUDS...THERE SHOULD BE ENOUGH SUN GETTING THROUGH TO COMBINE WITH SLIGHTLY WARMING 925MB TEMPS TO BRING TEMPERATURES UP A LITTLE EACH DAY. EVEN ON TUESDAY...WHEN THE SYSTEM APPROACHES...925MB TEMPS ARE ONLY -2 TO -4C. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY 255 PM CST SAT FEB 23 2013 THE LONG TERM FORECAST OVERALL IS FAIRLY QUIET. IN THE UPPER LEVEL PATTERN...THE ECMWF/GFS/CANADIAN CONTINUE TO FORECAST THAT THE WEAKENING STORM SYSTEM FROM TUESDAY IS GOING TO GET BOTTLED UP OVER THE GREAT LAKES REGION...ONLY SLOWLY MOVING TO THE EAST. THERE ARE TWO REASONS FOR THIS...1. THE SYSTEM IS HAVING TO GET THAT THROUGH THE RIDGING AHEAD OF IT AND 2. THERE IS ANOTHER FAIRLY POTENT SHORTWAVE TROUGH ON ITS HEELS COMING ACROSS THE SOUTHERN U.S. THAT EVENTUALLY GETS ABSORBED. WHAT THIS MEANS FOR OUR AREA IS THAT WE COULD SEE A GOOD 24 HOURS OR SO OF LIGHT SNOW FROM TUESDAY NIGHT INTO WEDNESDAY...ASSOCIATED WITH MOISTURE WRAPPING AROUND THE UPPER LOW. RAISED PRECIPITATION CHANCES SLIGHTLY...BUT FURTHER INCREASES ARE LIKELY NEEDED. ONCE THE UPPER LOW SHIFTS EAST...THEN HIGH PRESSURE BUILDS IN FROM THE U.S. AND CANADIAN PLAINS. HOWEVER...THE HIGH PRESSURE AREA DOES NOT LOOK TO BUILD INTO THE AREA UNTIL SATURDAY AT THE EARLIEST. A COMBINATION OF UPPER RIDGING BUILDING OVER THE WESTERN U.S. AND TROUGHING HOLDING IN PLACE OVER THE EASTERN U.S. LOOKS TO RESULT IN THIS SETUP. THEREFORE...A PROLONGED PERIOD OF DRY...NORTHERLY FLOW IS EXPECTED. DESPITE THE NORTHERLY FLOW...THE 850MB TEMPS BOTTOM OUT MAYBE AROUND -10C...THUS TEMPERATURES SHOULD HANG JUST BELOW NORMAL. && .AVIATION...THROUGH 18Z SUNDAY 1155 AM CST SAT FEB 23 2013 A SCATTERED TO BROKEN STRATUS DECK WILL BRING IFR CONDITIONS TO KRST AND MVFR CONDITIONS TO KLSE THROUGH EARLY AFTERNOON. HIGH PRESSURE IS EXPECTED TO BUILD IN LATE THIS AFTERNOON INTO THIS EVENING WITH SKIES CLEARING AND WINDS BECOMING LIGHT AND VARIABLE AT BOTH TAF SITES. AREAS OF FOG ARE EXPECTED TO DEVELOP AND COULD BE LOCALLY DENSE AT TIMES. LIFR CONDITIONS WILL DEVELOP AT KRST AROUND 9Z WITH VISIBILITIES FALLING TO 1/4 MILE. IFR CONDITIONS ARE EXPECTED AT KLSE AROUND 9Z WITH VISIBILITIES FALLING TO 2SM. THE FOG COULD FREEZE TO OBJECTS DEPOSITING A THIN LAYER OF FROST OR ICE. THE FOG WILL DISSIPATE IN THE 14-16Z TIMEFRAME WITH CONDITIONS GRADUALLY IMPROVING TO MVFR BY MID SUNDAY MORNING AND EVENTUALLY OF VFR BY THE LATE MORNING HOURS. && .ARX WATCHES/WARNINGS/ADVISORIES... 255 PM CST SAT FEB 23 2013 WI...FREEZING FOG ADVISORY FROM 10 PM THIS EVENING TO 9 AM CST SUNDAY FOR WIZ032>034-041-042-053>055-061. MN...FREEZING FOG ADVISORY FROM 10 PM THIS EVENING TO 9 AM CST SUNDAY FOR MNZ079-086>088-094>096. IA...FREEZING FOG ADVISORY FROM 10 PM THIS EVENING TO 9 AM CST SUNDAY FOR IAZ008>011-018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1156 AM CST SAT FEB 23 2013 .SHORT TERM...TODAY THROUGH MONDAY NIGHT 319 AM CST SAT FEB 23 2013 FORECAST CHALLENGES GOING THROUGH EARLY NEXT WEEK REVOLVE AROUND WHEN THE FLURRIES/SKIES CLEAR OUT TODAY/TONIGHT ALONG WITH WHEN THE NEXT ROUND OF LIGHT SNOW MAY MOVE IN ON MONDAY. CYCLONIC FLOW FROM THE SURFACE THROUGH THE UPPER ATMOSPHERE WILL LINGER ACROSS THE REGION FOR MUCH OF TODAY BEFORE A SURFACE TO UPPER LEVEL RIDGE AXIS PROPAGATES IN FROM THE WEST TONIGHT. WITH THE CYCLONIC FLOW HANGING ON FOR MUCH OF TODAY...EXPECT THAT THE CLOUD COVER AND FLURRIES/SNOW SHOWERS WILL CONTINUE AS WELL AND THAT THE DRY AIR TO THE SOUTHWEST WILL STRUGGLE TO MOVE IN. BY 00Z TONIGHT...THE 23.07Z RAP HAS THE SURFACE RIDGE ALIGNED ALONG THE MISSISSIPPI RIVER...SO AT LEAST EXPECT THAT THE FLURRIES WILL HAVE ENDED BY THEN ALONG AND WEST OF THE RIVER. HOWEVER...CLOUD COVER MAY LINGER WITH THE UPPER RIDGE STILL IN THE DAKOTAS. HAVE PLAYED CLOUD COVER A BIT ON THE PESSIMISTIC SIDE THROUGH TONIGHT AS A RESULT. BEYOND THIS THE PATTERN IS FAIRLY QUIET THROUGH THE REST OF THE WEEKEND AS THE RIDGE SHIFTS TO THE EAST WITH TEMPERATURES AND CLOUD COVER THE ONLY ISSUES TO CONTEND WITH. THERE IS NOT MUCH IN THE WAY OF LOW LEVEL COLD AIR ADVECTION KICKING IN BEHIND THIS SYSTEM...SO EXPECT THAT TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH MONDAY NIGHT. THE FOCUS THEN GOES TO THE NEXT SYSTEM THAT COULD IMPACT THE AREA WHICH IS A COMBINATION OF A NORTHERN STREAM WEAKENING MID LEVEL SHORT WAVE TROUGH AND A SOUTHERN STREAM DEEPENING LOW. THE TREND CONTINUES TO BE TO GO SLOWER WITH THE NORTHERN STREAM SHORT WAVE AS A BLOCKING RIDGE ALONG THE ATLANTIC COAST STALLS OUT THE FLOW. THE SURFACE REFLECTION FROM THIS SYSTEM IS A TROUGH THAT TRACKS ACROSS THE DAKOTAS AND STALLS ACROSS MINNESOTA AS THE SOUTHERN STREAM SYSTEM STARTS TO DEEPEN. THE 23.00Z GFS IS THE MOST ROBUST WITH QPF EXTENDING NORTH ALONG THIS SURFACE TROUGH WHILE THE REST OF THE GUIDANCE IS DRY. THEREFORE...HAVE BACKED OFF ON PRECIPITATION CHANCES FOR MONDAY NIGHT AND KEPT THEM RELEGATED TO PORTIONS OF SOUTH CENTRAL MINNESOTA INTO NORTHEAST IOWA. .LONG TERM...TUESDAY THROUGH FRIDAY 319 AM CST SAT FEB 23 2013 THIS AFOREMENTIONED SOUTHERN STREAM SYSTEM APPEARS TO BE COMING TOGETHER BY TUESDAY WITH THE 23.00Z GUIDANCE LOCKING IN ON A MORE SOUTHERN TRACK WITH THIS SURFACE LOW. THE 23.00Z GFS/ECMWF/GEM ALL ADVERTISE THIS LOW RUNNING FROM ST LOUIS OVER TO INDIANAPOLIS TUESDAY WHICH SHOULD KEEP THE MAIN BAND OF SNOW OFF TO THE SOUTHEAST. THE 23.00Z GFS IS FURTHEST TO THE NORTHWEST WHILE THE GEM/ECMWF ARE NEARLY IDENTICAL WITH THEIR TRACK. HAVE BACKED OFF ON SNOW CHANCES FOR TUESDAY ACROSS SOUTHWEST WISCONSIN AS A RESULT. AFTER THIS SYSTEM MOVES THROUGH...ANOTHER MID LEVEL TROUGH WILL DIG DOWN THROUGH THE NORTHWEST FLOW AND REINFORCE THE CUT OFF CLOSED LOW ACROSS THE EASTERN US. THIS WILL KEEP CYCLONIC FLOW IN PLACE ACROSS THE REGION THROUGH THURSDAY WITH SOME LIGHT SNOW POSSIBLE. THE 23.00Z GEM IS THE DRIEST OF THE GUIDANCE AND FOCUSES THIS TROUGH FURTHER TO THE SOUTH AND WOULD KEEP THE REGION ON THE DRY SIDE. DESPITE THESE HIGHLY AMPLIFIED SYSTEMS MOVING THROUGH THE UPPER MIDWEST...THE MAIN POOL OF COLD ARCTIC AIR IS CONFINED TO FAR NORTHERN CANADA WITH 850MB TEMPERATURES IN THE 0C TO -10C RANGE ACROSS THE SOUTHERN HALF OF CANADA. THUS...IT DOES NOT LOOK LIKE TEMPERATURES WILL TAKE MUCH OF A DIP AROUND HERE AS THE NORTHERLY FLOW SETS UP TOWARD MID WEEK. && .AVIATION...THROUGH 18Z SUNDAY 1155 AM CST SAT FEB 23 2013 A SCATTERED TO BROKEN STRATUS DECK WILL BRING IFR CONDITIONS TO KRST AND MVFR CONDITIONS TO KLSE THROUGH EARLY AFTERNOON. HIGH PRESSURE IS EXPECTED TO BUILD IN LATE THIS AFTERNOON INTO THIS EVENING WITH SKIES CLEARING AND WINDS BECOMING LIGHT AND VARIABLE AT BOTH TAF SITES. AREAS OF FOG ARE EXPECTED TO DEVELOP AND COULD BE LOCALLY DENSE AT TIMES. LIFR CONDITIONS WILL DEVELOP AT KRST AROUND 9Z WITH VISIBILITIES FALLING TO 1/4 MILE. IFR CONDITIONS ARE EXPECTED AT KLSE AROUND 9Z WITH VISIBILITIES FALLING TO 2SM. THE FOG COULD FREEZE TO OBJECTS DEPOSITING A THIN LAYER OF FROST OR ICE. THE FOG WILL DISSIPATE IN THE 14-16Z TIMEFRAME WITH CONDITIONS GRADUALLY IMPROVING TO MVFR BY MID SUNDAY MORNING AND EVENTUALLY OF VFR BY THE LATE MORNING HOURS. && .ARX WATCHES/WARNINGS/ADVISORIES... 319 AM CST SAT FEB 23 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM....HALBACH AVIATION...WETENKAMP