Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/13/13


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1049 AM MDT MON MAR 11 2013 .UPDATE... && .SHORT TERM...NORTHWEST FLOW ALOFT ACROSS REGION AT THIS TIME. MOISTURE HAS INCREASED ACROSS MOUNTAINS AS OROGRAPHICS IMPROVE. WEB CAMS SHOWING LIGHT SNOW OCCURRING ALONG CONTINENTAL DIVIDE OF SUMMIT GRAND AND BOULDER COUNTIES AS WELL AS THE HIGHER PEAKS IN ROCKY MOUNTAIN PARK. AIRMASS STILL FAIRLY STABLE WITH LAPSE RATES AROUND 5 C/KM. LATEST SATELLITE SHOWING JET STREAK MOVING ACROSS WYOMING AT THIS TIME. MOISTURE TO CONTINUE TO SPREAD INTO MOUNTAINS THIS AFTERNOON AND EVENING WITH CONTINUED OROGRAPHICS. LATEST RAP INDICATING LAPSE RATES IMPROVE TO AROUND 7 C/KM AS POCKET OF MID LEVEL COOLING MOVES OVER THE AREA. WILL MAKE SOME UPWARD ADJUSTMENTS TO POPS ACROSS MOUNTAINS THIS AFTERNOON BASED ON CURRENT TRENDS. WILL ALSO INCREASE SNOW AMOUNTS A BIT ALONG THE DIVIDE AND ACROSS ZONE 31 THIS AFTERNOON. ZONE 31 ON DOWNSLOPE SIDE OF THIS NORTHWEST FLOW SO AMOUNTS WILL STILL BE LIMITED. ACROSS PLAINS...SHOULD SEE SOME INCREASE IN MID AND HIGH LEVEL CLOUDS AS JET APPROACHES. SHOULD SEE SOME SHOWERS DEVELOP TOWARDS EVENING ACROSS NORTHEAST CORNER AWAY FROM DOWNSLOPE FLOW. LATEST RAP AND HRRR SUGGESTING SOME LIGHT PRECIP IN AN AREA EAST OF A GREELEY TO LIMON LINE AFTER 21Z...CONTINUING THROUGH THE EVENING. WILL MAKE SOME ADJUSTMENTS LATE THIS AFTERNOON FOR THIS TREND. SOME CONCERN FOR ANTICYCLONIC UPSLOPE DEVELOPING AS FAR WEST AS THE DENVER AREA THIS EVENING...WHICH COULD INCREASE SNOW CHANCES FOR DENVER. FOR NOW WILL CONTINUE WITH THE SLIGHT CHANCE FOR DENVER. MODELS HAVE BEEN CONSISTENT WITH SOME LIGHT QPF AND SNOW AMOUNTS THIS EVENING IN AN AREA OVER NORTHEAST WELD...MORGAN AND WASHINGTON COUNTIES INTO THE NORTHEAST CORNER. MAY NEED TO INCREASE POPS THERE FOR THE EVENING...FOR NOW WILL CONTINUE WITH THE CHANCE POPS. .AVIATION...WINDS SHIFTING TO THE NORTHWEST AS SYSTEM MOVES ACROSS WYOMING. NORTHWEST DIRECTION TO PREVAIL THROUGH THE AFTERNOON AS SOME MIXING STILL EXPECTED. STILL A SLIGHT CHANCE OF WINDS TURNING NORTHEAST TOWARDS EVENING...WITH LOWERING CEILINGS AND POSSIBLE ILS CONDITIONS. WILL CONTINUE TAF TRENDS AT THIS TIME. && .PREV DISCUSSION... /ISSUED 442 AM MDT MON MAR 11 2013/ SHORT TERM...A JET STREAK WILL DROP ACROSS NORTHEAST COLORADO TONIGHT. CURRENT MOUNTAIN WAVE WILL DIMINISH AS THE STABILITY STRUCTURE GOES AWAY. THERE IS A BRIEF DECREASE IN HIGH CLOUDS...THEN THEY SHOULD COME BACK THIS AFTERNOON. AREA OF LIFT WILL SLIDE ACROSS THE NORTHEAST CORNER OF THE STATE OVERNIGHT. NOT THAT IMPRESSED WITH WHAT IS HAPPENING UPSTREAM...AS AREAS UNDER THE LIFT NOW HAVE FAIRLY HIGH CEILINGS AND NOT MUCH PRECIPITATION. BUT THERE WILL BE SOME INSTABILITY UNDER THIS AREA AND THE LIFT IS REAL. MODELS ALL SHOW A BAND WITH SEVERAL INCHES OF SNOW THROUGH STERLING AND AKRON OVERNIGHT. AMOUNTS SEEM A BIT MUCH GIVEN THE MOISTURE AVAILABLE...BUT I WILL RAISE POPS IN THIS AREA. WITH A WESTERLY COMPONENT OFF THE GROUND...I WILL KEEP THE POPS AWAY FROM THE FRONT RANGE...WE WILL PROBABLY DEVELOP AN ANTICYCLONE WITH THE SHOWERS ON THE NORTHEAST SIDE OF THE LOW LEVEL SHEAR ZONE...SO PROBABLY NOT MUCH CHANCE FROM FORT COLLINS-DIA AND WESTWARD. FOR THE MOUNTAINS INCREASING MOISTURE AT OR BELOW MOUNTAINTOP LEVEL THIS AFTERNOON...WE SHOULD SEE SOME OROGRAPHIC SNOW THOUGH IT WILL NOT BE AS UNSTABLE AS WILL BE OVER THE PLAINS. NAM SNOWFALL OF UP TO 4 INCHES IS PROBABLY A BIT MUCH...BUT HERE TOO I WILL RAISE POPS FOR LIGHT SNOW. DROPPED LOW TEMPERATURES A BIT TONIGHT IN LINE WITH THE LATEST GUIDANCE. LONG TERM...FAIRLY STRONG NORTHWESTERLY FLOW ALOFT IS PROGGED FOR THE CWA TUESDAY THROUGH WEDNESDAY...DECREASING IN SPEED A BIT BY WEDNESDAY NIGHT BUT STILL TO STAY NORTHWESTERLY. MODELS KEEP AN UPPER RIDGE OVER THE WESTERN U.S. THROUGH THE PERIOD. THE SYNOPTIC SCALE ENERGY IS VERY WEAK AND DOWNWARD IN NATURE TUESDAY THROUGH WEDNESDAY NIGHT. THE BOUNDARY LAYER FLOW WILL MAINLY ADHERE TO NORMAL DIURNAL PATTERNS THROUGH THE PERIOD. CONCERNING MOISTURE...THERE IS SOME PROGGED IN THE LOWER LEVELS ON TUESDAY. BY TUESDAY NIGHT...MOISTURE DECREASES OVER THE EASTERN HALF OF THE CWA...WITH SOME LINGERING OVER THE MOUNTAINS. WEDNESDAY AND WEDNESDAY NIGHT ARE PRETTY DRY. THE QPF FIELDS HAVE A TAD OF MEASURABLE SNOW OVER THE HIGH MOUNTAINS TUESDAY MORNING...THEN THERE IS NOTHING ANYWHERE THROUGH WEDNESDAY NIGHT. WILL KEEP MINOR POPS GOING IN THE HIGH MOUNTAINS TUESDAY INTO TUESDAY EVENING...THATS IT. FOR TEMPERATURES...TUESDAY`S HIGHS DO NOT LOOK AS WARM AS THEY DID FROM YESTERDAY`S 00Z MODEL RUNS. THEY ARE NOW 0-2 C COOLER THAN TODAY`S EXPECTED READINGS. WEDNESDAY`S HIGHS ARE 3-8 C WARMER THAN TUESDAY`S HIGHS. FOR THE LATER DAYS...THURSDAY THROUGH SUNDAY...THE UPPER RIDGE IS PROGGED TO SLOWLY MAKE ITS WAY EAST GETTING OVER COLORADO ON FRIDAY. THE ECMWF STILL SHOWS A WEAK UPPER TROUGH TO MOVE INTO THE CWA...BUT NOW IT MOVE ACROSS LATE SATURDAY INTO SATURDAY NIGHT AND IT IS WEAKER THAN YESTERDAY`S RUN INDICATED. WILL INCREASE CLOUDINESS A BIT SATURDAY AND SUNDAY... BUT NO POPS FOR THE LAST FOUR DAYS ANYWHERE. TEMPERATURES LOOK TO BE ABOVE SEASONAL NORMALS ALL FOUR DAYS. AVIATION...VFR CONDITIONS TODAY. NORTH TO NORTHWEST WINDS SHOULD MIX DOWN BY EARLY AFTERNOON...TURNING NE OR POSSIBLY SE BY EARLY EVENING. CEILINGS MAY LOWER ENOUGH TO REQUIRE INSTRUMENT APPROACHES TO KDEN OVERNIGHT...THOUGH THERE IS ONLY A SLIGHT CHANCE OF SNOW SHOWERS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....RJK AVIATION...D-L
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
649 PM EDT MON MAR 11 2013 ...SHALLOW COASTAL FLOODING AROUND HIGH TIDE THIS EVENING ALONG THE LOWER SOUTH CAROLINA COAST... .SYNOPSIS... HIGH PRESSURE WILL SHIFT OFFSHORE THROUGH THE EVENING. A COLD FRONT WILL ADVANCE INTO CENTRAL GEORGIA AND THE CAROLINAS TONIGHT. THE FRONT WILL MOVE OFF THE COAST TUESDAY MORNING FOLLOWED BY HIGH PRESSURE THROUGH SATURDAY. A WEAK BACKDOOR COLD FRONT MAY APPROACH FROM THE NORTH ON SUNDAY AND POSSIBLY LINGER IN THE AREA INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... UPPER LEVEL LOW PRESSURE SPINNING OVER SOUTHERN MICHIGAN WILL WEAKEN TONIGHT AS IT MOVES NORTH INTO SOUTHERN QUEBEC AND SOUTHEAST ONTARIO. THE ATTENDANT COLD FRONT STRETCHES FROM SURFACE LOW PRESSURE NEAR SOUTHERN LAKE MICHIGAN SOUTH THROUGH THE OHIO AND TENNESSEE VALLEYS AND INTO THE CENTRAL GULF OF MEXICO. THE FRONT WILL STEADILY MARCH EAST AND POSITIONED BE VERY NEAR THE COAST BY SUNRISE TUESDAY. GOES-EAST WATER VAPOR IMAGERY SHOWS A LARGE PLUME OF TROPICAL MOISTURE SURGING NORTH ACROSS MUCH OF THE EASTERN U.S. WITH BLENDED AMSU/SSMI DATA PINGING PWATS IN EXCESS OF 1.50 INCHES ACROSS SOUTHERN ALABAMA AND GEORGIA. THESE VALUES WILL ADVECT EAST INTO SOUTHERN SOUTH CAROLINA AND SOUTHEAST GEORGIA BY MIDNIGHT AS PRE-FRONTAL LOW-LEVEL JETTING STRENGTHENS. RAIN CHANCES WILL STEADILY INCREASE FROM WEST-EAST OVERNIGHT AS THE COLD FRONT DRAWS CLOSER AND SHORTWAVE ENERGY CURRENTLY MOVING ACROSS THE SOUTHERN MISSISSIPPI VALLEY EJECTS NORTHEAST ACROSS NORTHERN GEORGIA AND THE SOUTHERN APPALACHIANS. WILL INCREASE POPS TO 100 PERCENT FOR ALL AREAS TONIGHT WITH THE BULK OF THE HEAVIEST RAINS LIKELY FALLING BETWEEN MIDNIGHT AND SUNRISE...POSSIBLY A BIT EARLIER ACROSS FAR INTERIOR SOUTHEAST GEORGIA. GENERALLY USED A BLEND OF THE HIGHER RESOLUTION H3R AND RAP RUNS TO CONSTRUCT HOURLY WEATHER PARAMETERS THROUGH 6 AM. AVERAGE RAIN AMOUNTS OF 0.25-0.75 INCH LOOKS REASONABLE WITH LOCALLY HIGHER VALUES LIKELY. HOURLY TEMPERATURES WILL BE A BIT ATYPICAL WITH THE AREA HOLDING WELL INTO THE WARM SECTOR UNTIL EARLY TUESDAY MORNING. LOWS WILL RANGE FROM THE MID 50S ACROSS FAR INTERIOR SOUTHEAST GEORGIA TO THE LOWER 60S AT THE COAST. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... TUESDAY...THERE ARE SOME SLIGHT TIMING DIFFERENCES REGARDING THE COLD FRONTAL PASSAGE IN THE LATEST 12Z NUMERICAL MODEL SOLUTIONS...YET EVEN THE SLOWEST SCENARIOS HAVE THE FRONT OFFSHORE BY MID TO LATE MORNING. WILL THUS CONTINUE TO ADVERTISE 70 TO 80 PERCENT RAIN CHANCES GENERALLY ALONG AND EAST OF INTERSTATE 95 AT DAYBREAK...WITH POPS 50 PERCENT AND LOWER JUST TO THE WEST. PRECIPITATION POTENTIAL WILL RAPIDLY DIMINISH BEHIND THE FRONT AS THE MORNING PROGRESSES...AND HAVE INDICATED ONLY SLIGHT CHANCES REMAINING FOR THE CHARLESTON TRI COUNTY AREA BY MID AFTERNOON. TEMPERATURES WILL ONLY BE A FEW DEGREES COOLER THAN MONDAY...PEAKING FROM 70 TO 72 DEGREES...A COMBINED RESULT OF DELAYED COLD ADVECTION BEHIND THE FRONT AND THE WARMING EFFECTS OF INCREASING SUNSHINE AND DOWNSLOPE FLOW. MINIMUM TEMPERATURES TUESDAY NIGHT WILL REFLECT THE COOLING TREND...FALLING MORE THAN 10 DEGREES LOWER THAN THE PREVIOUS NIGHT...INTO THE 40 DEGREE RANGE. WEDNESDAY AND THURSDAY...THE AXIS OF A SHORTWAVE TROUGH WILL SWING ACROSS THE EAST COAST WEDNESDAY AFTERNOON...AS CENTRAL CANADIAN HIGH PRESSURE BUILDS INTO THE REGION THROUGH THE LATE WEEK PERIOD. STRONG COLD ADVECTION WILL INITIATE ACCORDINGLY...AND WHEN COMBINED WITH LOWERING HEIGHTS ALOFT...WILL SUPPRESS HIGH TEMPERATURES IN THE MID TO UPPER 60S WEDNESDAY AFTERNOON. BREEZY CONDITIONS ARE ALSO EXPECTED DURING THE DAYTIME HOURS ON WEDNESDAY...AS DECENT DIURNAL MIXING TAPS INTO 30 KT BOUNDARY LAYER WINDS. HIGH TEMPERATURES WILL ACTUALLY BE A DEGREE OR TWO LOWER ON THURSDAY...WITH WINDS VEERING TOWARD THE NORTH AND DOWNSLOPE WARMING EFFECTS DIMINISHING. ABUNDANT SUNSHINE AND DRY CONDITIONS WILL PREVAIL. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A BROAD UPPER RIDGE WILL SPREAD EAST THURSDAY NIGHT THROUGH SATURDAY...SUPPORTING A WARMING TREND AND DRY WEATHER. TEMPERATURES WILL BE BACK INTO THE 70S BY SATURDAY GIVEN CURRENT TRENDS. UNCERTAINTY INCREASES SUNDAY INTO MONDAY CONSIDERING SOME DISCREPANCIES IN MEDIUM RANGE MODEL SOLUTIONS. THE LATEST ECMWF IS STILL SHOWING A PRONOUNCED UPPER TROUGH DIGGING INTO THE CENTRAL UNITED STATES ON MONDAY...WITH THE 12Z GFS COMING MORE INTO LINE WITH THIS SCENARIO. HAVE MAINTAINED A DRY EXTENDED FORECAST WITH ABOVE NORMAL TEMPERATURES...WHILE SHOWING AN INCREASE IN CLOUD COVER TO ACCOUNT FOR A MORE UNSETTLED PATTERN TOWARD THE END OF THE PERIOD. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... TO BE ISSUED SHORTLY. EXTENDED AVIATION OUTLOOK...THERE ARE NO CONCERNS WITH A GREATER THAN 30 PERCENT CONFIDENCE AT THIS TIME. && .MARINE... TONIGHT...LATEST SWAN AND WW4 OUTPUT SUGGEST 6 FT SEAS WILL AFFECT THE GEORGIA NEARSHORE WATERS LATER TONIGHT THROUGH TUESDAY MORNING. EXPANDED THE SMALL CRAFT ADVISORY INTO THIS AREA GIVEN THIS LATEST MODEL TREND. WINDS/SEAS WILL THEN INCREASE/BUILD OVER ALL WATERS TONIGHT AS LOW LVL WINDS ENHANCE OVER THE WATERS AND THE COLD FRONT APPROACHES THE COAST LATE. SOUTHERLY FLOW INCREASING TO 15-20 WITH GUSTS TO 25 KT IS FORECAST TO BUILD SEAS TO 4-6 FT WITHIN 20 NM AND 5-8 FT 20-60 NM OFFSHORE. A SMALL CRAFT ADVISORY WILL THEREFORE REMAIN IN EFFECT FOR MARINE LEGS WITH THE EXCEPTION OF THE CHARLESTON HARBOR. WINDS AND SEAS FOR THE NEARSHORE WATERS WILL DIMINISH BELOW ADVISORY CRITERIA NO LATER THAN TUESDAY AFTERNOON AS THE COLD FRONT PUSHES OFFSHORE...WHILE SEAS MAINTAIN ADVISORY CONDITIONS ACROSS THE OUTER GEORGIA WATERS. COLD ADVECTION WILL BE SLIGHTLY DELAYED BEHIND THE FRONT...WITH THE MAIN SURGE EXPECTED MORE TOWARD WEDNESDAY. THE DEEPEST MIXING WILL BE ACROSS THE WARMER OFFSHORE WATERS...MAINLY BEYOND 20 NM FROM THE COAST. THUS THE OUTER GEORGIA MARINE ZONES WILL REMAIN UNDER A SMALL CRAFT ADVISORY THROUGH THURSDAY. FREQUENT GUSTS UP TO 25 KT ACROSS PORTIONS OF THE NEARSHORE WATERS COULD NECESSITATE ADVISORIES FOR THOSE AREAS AS WELL. MUCH WEAKER FLOW EXPECTED THURSDAY INTO THE WEEKEND AS HIGH PRESSURE BUILDS FROM THE WEST/NORTHWEST. && .TIDES/COASTAL FLOODING... TIDES ANOMALIES ARE RUNNING 1 FT ABOVE PREDICTED IN THE CHARLESTON HARBOR EARLY THIS EVENING. CURRENT TRENDS SUGGEST TIDE LEVELS WILL PEAK VERY NEAR 7.0 FT MLLW WITH HIGH TIDE THIS EVENING. THE SITUATION LOOKS MARGINAL...BUT GIVEN THE AMOUNT OF TIDAL LOADING THAT HAS OCCURRED OVER THE PAST SEVERAL HIGH TIDES...WILL HOIST A COASTAL FLOOD ADVISORY FOR THE SOUTH CAROLINA COASTAL ZONES...EXCLUDING TIDAL BERKELEY...FROM 8 PM UNTIL 11 PM. HIGH TIDE WILL OCCUR IN THE CHARLESTON HARBOR AT 844 PM AND IN THE BEAUFORT RIVER AT BEAUFORT AT 959 PM. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...COASTAL FLOOD ADVISORY UNTIL 11 PM EDT THIS EVENING FOR SCZ048>051. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT TUESDAY FOR AMZ350-352. SMALL CRAFT ADVISORY UNTIL 11 AM EDT TUESDAY FOR AMZ354. SMALL CRAFT ADVISORY UNTIL 2 PM EDT THURSDAY FOR AMZ374. && $$ ST
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
141 PM EDT MON MAR 11 2013 .AVIATION... VARIABLE CIGS IMPACTED KSBN FOR A SHORT PERIOD OF TIME IN THE WAKE OF THE FRONTAL BOUNDARY SWEEPING ACROSS THIS MORNING. LOW CLOUDS ASSOCIATED WITH THE UPPER LOW ITSELF WERE DRIFTING BACK IN FROM ILLINOIS AND WILL CAUSE A RETURN TO LOW END MVFR CONDITIONS WITH SOME EXCURSIONS TO IFR POSSIBLE TONIGHT. AT KFWA TAFS HAVE BEEN ADJUSTED TO REFLECT THE TEMP IMPROVEMENT IN FLGT CONDITIONS BEFORE RETURNING LATER THIS AFTERNOON. NO FURTHER DETAIL ADDED BEYOND 00-02Z WITH PERSISTENT CAA AND LOW CLOUDS WITH UPPER LOW LINGERING ACROSS THE AREA THROUGH THE REMAINDER OF THE PERIOD. && .UPDATE... SECOND UPDATE OF THE DAY ISSUED TO ADJUST FOR RADAR TRENDS AS RETURNS CONTINUE TO INCREASE AHEAD OF AND JUST BEHIND FAST MOVING FRONT. HRRR FOR PAST FEW HOURS HAS HINTED AT A BIT OF A FINE LINE OF COVECTION POSSIBLY DEVELOPING AND RECENT TREDNS SUGGEST THIS MAY BE UNDERWAY NEAR THE IN/OH STATE LINE AS SFC DWPTS APPROACH 50 DEGREES. ONE STRAY LIGHTNING STRIKE WAS DETECTED NOT TO LONG AGO EAST OF AUBURN INDIANA. WHILE THERE MAY ONLY BE ONE OR 2 MORE STRIKES PRIOR TO DEPARTURE FROM THE AREA OPTED TO ADD SLGT CHC MENTION TO ZONES/GRIDS FOR A FEW HOURS. OTHERWISE PRECIP WILL COME TO AND END FROM SW TO NE THROUGH THE AFTERNOON WITH GENERALLY DRY CONDTIONS ALREADY SEEN ALONG AND WEST OF US 31. TEMPS WILL FALL OFF AS THE RAIN CLEARS WITH READINGS DROPPING INTO THE 30S. HOWEVER...ANY MIX OR SWITCH TO SNOW STILL LOOKS TO OCCUR CLOSER TO/AFTER 00Z. WILL ADDRESS IN REGULAR FORECAST PACKAGE. && .PREV DISCUSSION... /ISSUED 433 AM EDT MON MAR 11 2013/ SHORT TERM... DEEP LYRD CYCLONE OVR CNTRL IA WILL LIFT OUT THROUGH NRN LWR MI TONIGHT AS SFC FNTL ZONE SHIFTS EWD ACRS CWA TDA. RAINFALL IN ASSOCN/W THIS SYS HAS LARGELY BEEN A BUST SO FAR TIED TO POOR EWD MOISTENING AS PLAINLY ILLUSTRATED IN 00Z RAOBS FM ILN/DTX. HWVR W/SFC BNDRY STILL PLANTED THROUGH CNTRL IL AND CONTD WARM SECTOR LL MSTR FLUX -SHRA WOULD STILL APPEAR TO BE A GOOD PROSPECT THROUGH EARLY AFTN TIED TO NEARING SFC FNTL ZONE AND ASSOCD LL SATURATED ASCENT. OTRWS WELL DVLPD WRAP AROUND DEFORMATION ZONE ACRS WRN IA LOOKS TO CARRY EWD AND GRAZE MUCH OF THE AREA LT THIS AFTN/EARLY THIS EVENING W/A PD OF LT SNOW SHOWERS...TIMED W/INTENSIFYING LL THERMAL TROUGHING. HWVR MARGINAL VERTICAL ASCENT/SFC TEMPS SHLD YIELD LTL TO NO SNOW ACCUMULATION THIS EVENING. SECONDARY FOLLOWING UPR DISTURBANCE DROPPING WWD THROUGH BASE OF LARGER SCALE TROUGH POSITIONED THROUGH THE WRN LAKES ON TUE SHLD YIELD ENHANCED DIURNAL SHSN TUE AFTN/EVE AND WILL BACK/EXPAND PRIOR POPS QUITE A BIT IN CONCERT W/EVEN STRONGER/DEEPER LL THERMAL TROUGHING AND UNDER GUISE OF STEEP LL LAPSE RATES DVLPG IN MOIST CYCLONIC FLW. DIFFICULT NR TERM TEMP FCST GIVEN WWD POSITION OF SFC CDFNT THIS MORNING. WILL GENERALLY FOLLOW CLOSE KNIT MOS BLEND WHICH YIELDS A PREFERRED NON-DIURNAL CURVE WRN HALF AND FLAT LINES ERN HALF. MUCH COLDER AIR TO FILTER IN OVERNIGHT AND AGAIN LT TUE. LONG TERM... WEDNESDAY THROUGH SUNDAY...VERY COLD AIR WILL BE OVER THE FORECAST AREA WEDNESDAY WITH THE LIKELIHOOD OF A WEAK SHORT WAVE TROF MOVING ACROSS THE WESTERN GREAT LAKES REGION. HAVE ADDED A CHANCE FOR SNOW SHOWERS MOST AREAS WEDNESDAY GIVEN SHALLOW BUT STEEP LAPSE RATES EXPECTED WITH RESIDUAL MOISTURE FROM RECENT SNOWMELT AND LIGHT PRECIPITATION IN CONJUNCTION WITH DAYTIME HEATING. EXPECT ALSO SOME LAKE ENHANCEMENT UPSTREAM WITH FAVORABLE PRECONDITIONING OF THE LOW LEVELS. AFTER WEDNESDAY...A ECMWF/GFS CONSENSUS FAVORS THE FLOW BECOMING HIGH ZONAL LATE IN THE WEEK WITH MODERATING TEMPERATURES... SO CONTINUED TO TREND HIGHS WARMER FRIDAY. HOWEVER...CONFIDENCE BECOMES VERY POOR BY SUNDAY AS REFLECTED IN THE GFS MEX MODEL OUTPUT WITH VERY HIGH STANDARD DEVIATIONS...THUS...TRIED TO KEEP PERSISTENCE FOR THE 2ND HALF OF THIS PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT WEDNESDAY FOR LMZ043-046. && $$ SHORT TERM...T LONG TERM...SKIPPER AVIATION...FISHER UPDATE...FISHER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
313 PM MDT MON MAR 11 2013 .SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY) ISSUED AT 1215 PM MDT MON MAR 11 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS INDICATE NW FLOW IN PLACE ACROSS PLAINS WITH TROUGH OVER GREAT LAKES AND RIDGE BUILDING ALONG WEST COAST. SEVERAL WEAK SHORTWAVES WITHIN THE MEAN FLOW HAVE LEAD TO DEVELOPMENT OF HIGH CLOUDS ACROSS THE REGION. PRIMARY FORECAST CONCERN FOR SHORT TERM WILL BE POTENTIAL FOR LIGHT SNOW LATE TONIGHT ACROSS THE CWA. A FAST MOVING SHORTWAVE TROUGH OVER THE NORTHERN PLAINS WILL SHIFT SOUTH THIS EVENING AND OVER THE CWA TONIGHT. LARGE SCALE FORCING IS ADVERTISED ACROSS THE CENTRAL PART OF THE CWA...WITH MOISTURE PROFILES SATURATING LATER THIS EVENING. THERE IS GOOD MODEL OVERLAP IN TIMING OF QPF FROM WEST TO EAST THROUGH THE EVENING AND OVERNIGHT...WITH PRECIP STARTING AS RAIN LATE THIS AFTERNOON OVER EASTERN COLORADO AND TRANSITIONING TO ALL SNOW THIS EVENING. WITH INCREASING CONFIDENCE IN MEASURABLE PRECIP I INCREASED POPS TO LIKELY CATEGORY ACROSS THE CENTRAL PART OF THE CWA IN LINE WITH MODEL CONSENSUS. THERE IS STILL WEAK INSTABILITY ADVERTISED WITH SNOW BAND...AND WITH STRONG FRONTOGENESIS IMMEDIATELY BEHIND SHORTWAVE WE COULD SEE NARROW BANDING. QPF AMOUNTS ARE GENERALLY LIGHT...AND WITH MARGINAL MOISTURE ADVECTION AND THE FAST NATURE OF THIS SYSTEM I AM ONLY ANTICIPATING AROUND ONE INCH OF SNOWFALL AT THE MOST. ANY LINGERING SNOW SHOULD QUICKLY COME TO AN END AROUND SUNRISE TUESDAY MORNING. DRY CONDITIONS ARE THEN EXPECTED THROUGH THE REST OF THE DAY TUESDAY WITH ONLY HIGH CLOUDS POSSIBLY LINGERING THROUGH THE DAY. AIR MASS SHOULD BE COOLER THAN TODAY...THOUGH IMPACTS FROM SNOW PACK SHOULD BE MINIMAL. WE COULD SEE IMPACT FROM SKY COVER...BUT FOR NOW I KEPT FORECAST SIMILAR TO TODAY...WITH MID/UPPER 40S IN THE NORTHEAST TO LOW 50S IN THE SOUTHWEST. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 255 PM MDT MON MAR 11 2013 FORECAST CONCERN IN THE LONG TERM PERIOD IS THE POSSIBILITY OF PRECIPITATION THIS WEEKEND. THE AXIS OF THE BROAD UPPER RIDGE TRANSLATES FROM THE WEST COAST TO THE INTERMOUNTAIN AND ROCKY MOUNTAIN REGION BETWEEN TUESDAY NIGHT AND THURSDAY NIGHT. BY FRIDAY THE RIDGE BEGINS TO FLATTEN AS SEVERAL SHORT WAVE TROUGH BEGIN TO RIDE UP OVER THE APEX OF THE RIDGE. THESE WAVES ARE EXPECTED TO REMAIN NORTH OF THE CENTRAL HIGH PLAINS REGION THROUGH AT LEAST SATURDAY MORNING. THEREFORE...THE FORECAST AREA IS EXPECTED TO REMAIN DRY AND WARM THROUGH SATURDAY NIGHT WITH A PERSISTENT LEE TROUGH REMAINING IN PLACE IN THE VICINITY OF THE EASTERN COLORADO BORDER AREA. EARLY SATURDAY...IT APPEARS THAT A COOLER AREA OF HIGH PRESSURE WILL MOVE SOUTHWARD ACROSS THE PLAINS STATES WITH A BACKDOOR COLD FRONT PUSHING INITIALLY INTO THE EASTERN PORTION OF THE FORECAST AREA WITH COOLER AIR REMAINING GENERALLY IN PLACE ACROSS THE PLAINS THROUGH THE END OF THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. THE GFS AND ECMWF ARE NO LONGER COMPLETELY OUT OF PHASE WITH EACH OTHER AT THIS POINT...BUT CONTINUE TO OFFER SOMEWHAT DIFFERENT SOLUTIONS WITH THE NEXT UPPER TROUGH ENTERING THE PACIFIC NORTHWEST AND TRACKING EAST OF THE ROCKIES SOMETIME IN THE SUNDAY TO SUNDAY NIGHT TIME FRAME. WITH SEVERAL SMALLER SHORT WAVE TROUGHS PRECEDING THE MAIN UPPER TROUGH AND WITH THE APPROACH AND PASSAGE OF THE MAIN UPPER TROUGH...EXPECT AT LEAST A SLIGHT CHANCE OF PRECIPITATION OVER THE FORECAST AREA FROM LATE SATURDAY THROUGH AT LEAST SUNDAY NIGHT AND POSSIBLY THE DAY ON MONDAY...DEPENDING UPON THE MODEL SOLUTION THAT ENDS UP CLOSER TO REALITY. HAVE THEREFORE GONE WITH A FAIRLY BROAD BRUSHED SOLUTION THROUGH THE WEEKEND AND INTO MONDAY WITH A SLIGHT CHANCE OF LIGHT RAIN WITH LIGHT ACCUMULATIONS DURING THAT TIME. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1134 AM MDT MON MAR 11 2013 VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THIS EVENING AT BOTH TERMINALS. MVFR CONDITIONS WILL DEVELOP OVER KGLD AT A BAND OF RAIN/SNOW DEVELOPS LATE THIS AFTERNOON AND EVENING OVER EASTERN COLORADO AND SPREADS INTO NORTHWEST KANSAS AS ALL SNOW TONIGHT. I COULDNT RULE OUT BRIEF IFR CONDITIONS ALONG MOST INTENSE PART OF SNOW BAND TONIGHT...HOWEVER I WAS NOT CONFIDENT ENOUGH TO PREVAIL OR INCLUDE TEMPO GROUP...SINCE LOCATION OF THIS BAND IS STILL IN QUESTION. CHANCE ARE LOWER FOR PRECIP/MVFR AT AT THE KMCK TERMINAL SO CURRENTLY HAVE VFR CONTINUING WITH VCSH. VFR CONDITIONS SHOULD PREVAIL AT BOTH TERMINALS AFTER 12Z WHEN PRECIP QUICKLY MOVES EAST. WINDS HAVE BEEN SLOWER TO INCREASE AT BOTH TERMINALS TODAY WITH THICK HIGH CLOUDS OVERHEAD.I STILL EXPECT WIND GUSTS AROUND 20KT BY MID AFTERNOON...DECREASING AROUND SUNSET. GUSTY WEST WINDS SHOULD REDEVELOP AROUND 15Z TUESDAY WITH CLEARING SKIES AND BETTER DAYTIME MIXING. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...LOCKHART AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1215 PM MDT MON MAR 11 2013 .SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY) ISSUED AT 1215 PM MDT MON MAR 11 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS INDICATE NW FLOW IN PLACE ACROSS PLAINS WITH TROUGH OVER GREAT LAKES AND RIDGE BUILDING ALONG WEST COAST. SEVERAL WEAK SHORTWAVES WITHIN THE MEAN FLOW HAVE LEAD TO DEVELOPMENT OF HIGH CLOUDS ACROSS THE REGION. PRIMARY FORECAST CONCERN FOR SHORT TERM WILL BE POTENTIAL FOR LIGHT SNOW LATE TONIGHT ACROSS THE CWA. A FAST MOVING SHORTWAVE TROUGH OVER THE NORTHERN PLAINS WILL SHIFT SOUTH THIS EVENING AND OVER THE CWA TONIGHT. LARGE SCALE FORCING IS ADVERTISED ACROSS THE CENTRAL PART OF THE CWA...WITH MOISTURE PROFILES SATURATING LATER THIS EVENING. THERE IS GOOD MODEL OVERLAP IN TIMING OF QPF FROM WEST TO EAST THROUGH THE EVENING AND OVERNIGHT...WITH PRECIP STARTING AS RAIN LATE THIS AFTERNOON OVER EASTERN COLORADO AND TRANSITIONING TO ALL SNOW THIS EVENING. WITH INCREASING CONFIDENCE IN MEASURABLE PRECIP I INCREASED POPS TO LIKELY CATEGORY ACROSS THE CENTRAL PART OF THE CWA IN LINE WITH MODEL CONSENSUS. THERE IS STILL WEAK INSTABILITY ADVERTISED WITH SNOW BAND...AND WITH STRONG FRONTOGENESIS IMMEDIATELY BEHIND SHORTWAVE WE COULD SEE NARROW BANDING. QPF AMOUNTS ARE GENERALLY LIGHT...AND WITH MARGINAL MOISTURE ADVECTION AND THE FAST NATURE OF THIS SYSTEM I AM ONLY ANTICIPATING AROUND ONE INCH OF SNOWFALL AT THE MOST. ANY LINGERING SNOW SHOULD QUICKLY COME TO AN END AROUND SUNRISE TUESDAY MORNING. DRY CONDITIONS ARE THEN EXPECTED THROUGH THE REST OF THE DAY TUESDAY WITH ONLY HIGH CLOUDS POSSIBLY LINGERING THROUGH THE DAY. AIR MASS SHOULD BE COOLER THAN TODAY...THOUGH IMPACTS FROM SNOW PACK SHOULD BE MINIMAL. WE COULD SEE IMPACT FROM SKY COVER...BUT FOR NOW I KEPT FORECAST SIMILAR TO TODAY...WITH MID/UPPER 40S IN THE NORTHEAST TO LOW 50S IN THE SOUTHWEST. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 224 AM MDT MON MAR 11 2013 IN THE EXTENDED (THUR-SUN)...MEDIUM RANGE MODELS BEGIN THE PERIOD IN REASONABLE AGREEMENT WITH LARGE RIDGE CENTERED OVER THE INTERMOUNTAIN WEST...BUT FAIRLY QUICKLY BECOME OUT OF PHASE WITH EACH OTHER OVER THE WEEKEND LEADING TO A FAIRLY LOW CONFIDENCE FORECAST FOR THE AREA. WHILE THERE DOES APPEAR TO BE SOME THREAT FOR PRECIPITATION IN THE SATURDAY-SUNDAY PERIOD...POSSIBILITY STRETCHES FOR SEVERAL PERIODS DUE TO DIFFERENCES IN MODEL TIMING/OVERALL PATTERN. GIVEN OVERALL CONFIDENCE LOW...THINK TRYING TO PICK AN SPECIFIC PERIOD TO ENHANCE POPS NOT WARRANTED ATTM AND WILL CONTINUE DRY FORECAST FOR CWA. FOR TEMPERATURES...CONFIDENCE REMAINS HIGH THAT TEMPERATURES WILL WARM INTO THE 70S THROUGH FRIDAY BUT WITH AFOREMENTIONED CONCERNS...THINK KEEPING TEMPS AROUND CONSENSUS VALUES WARRANTED FOR REST OF PERIOD DUE TO UNCERTAINTY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1134 AM MDT MON MAR 11 2013 VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THIS EVENING AT BOTH TERMINALS. MVFR CONDITIONS WILL DEVELOP OVER KGLD AT A BAND OF RAIN/SNOW DEVELOPS LATE THIS AFTERNOON AND EVENING OVER EASTERN COLORADO AND SPREADS INTO NORTHWEST KANSAS AS ALL SNOW TONIGHT. I COULDNT RULE OUT BRIEF IFR CONDITIONS ALONG MOST INTENSE PART OF SNOW BAND TONIGHT...HOWEVER I WAS NOT CONFIDENT ENOUGH TO PREVAIL OR INCLUDE TEMPO GROUP...SINCE LOCATION OF THIS BAND IS STILL IN QUESTION. CHANCE ARE LOWER FOR PRECIP/MVFR AT AT THE KMCK TERMINAL SO CURRENTLY HAVE VFR CONTINUING WITH VCSH. VFR CONDITIONS SHOULD PREVAIL AT BOTH TERMINALS AFTER 12Z WHEN PRECIP QUICKLY MOVES EAST. WINDS HAVE BEEN SLOWER TO INCREASE AT BOTH TERMINALS TODAY WITH THICK HIGH CLOUDS OVERHEAD.I STILL EXPECT WIND GUSTS AROUND 20KT BY MID AFTERNOON...DECREASING AROUND SUNSET. GUSTY WEST WINDS SHOULD REDEVELOP AROUND 15Z TUESDAY WITH CLEARING SKIES AND BETTER DAYTIME MIXING. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JRM AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1112 PM MDT SUN MAR 10 2013 .UPDATE... ISSUED AT 540 PM MDT SUN MAR 10 2013 WINDS HAD DECREASED TO BELOW ADVISORY CRITERIA SO WIND ADVISORY HAS BEEN CANCELLED. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 143 PM MDT SUN MAR 10 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LONG WAVE TROUGH EXTENDING FROM GREAT LAKES ACROSS THE THE CENTRAL PLAINS WITH BASE OF TROUGH OVER BAJA PENINSULA. STACKED H7/H5 CLOSED LOW CENTER IS CURRENTLY OVER NE KANSAS WITH SHORTWAVE RIDGE BUILDING ACROSS WESTERN US INTO THE NORTHERN PLAINS ON THE BACK SIDE OF THIS SYSTEM. BETWEEN THE RIDGE AND CLOSED LOW A STRONG AXIS OF SUBSIDENCE IN IN PLACE ACROSS OUR CWA. TIGHT PRESSURE GRADIENT IS CURRENTLY IN PLACE ACROSS THE EASTERN HALF OF THE CWA WITH HIGH PRESSURE BUILDING OVER EASTERN COLORADO AND STRONG SURFACE LOW PRESSURE CENTERED OVER MISSOURI. GRADIENT WILL CONTINUE TO WEAKEN AS LARGE SCALE SYSTEM PULLS EAST THIS AFTERNOON AND HIGH PRESSURE CONTINUES TO BUILD OVER THE CWA. WE ARE ALREADY SEEING WINDS DECREASE BELOW ADVISORY CRITERIA OVER THE NW HALF OF THE CWA. WINDS CONTINUE TO HOVER RIGHT AT OR ABOVE ADVISORY CRITERIA WITH BETTER THAN ANTICIPATED AFTERNOON MIXING ACROSS THE SE HALF OF THE AREA. I DECIDED TO EXTEND ADVISORY 00Z...THOUGH WE MIGHT BE ABLE TO EXPIRE THE ADVISORY EARLY ESPECIALLY FOR THE NW COUNTIES. WINDS WILL DECREASE RAPIDLY AROUND SUNSET WITH LIGHT W/NW WINDS EXPECTED OVERNIGHT TONIGHT. WITH SHORTWAVE RIDGE BUILDING EAST FLOW ALOFT WITH SHIFT TO A NW WITH LEE TROUGH BEGINNING TO REDEVELOP OVER EASTERN COLORADO BY 12Z TONIGHT. EARLY THIS AFTERNOON EASTERN LOCATIONS COULD STILL SEE A FEW FLURRIES AS ENERGY ROTATES ON THE BACK SIDE OF UPPER LOW...HOWEVER BEYOND THIS THE FORECAST SHOULD REMAIN DRY THROUGH THE DAYTIME PERIOD MONDAY. THERE WILL BE A MODERATION OF THE AIR MASS OVER OUR CWA FROM THE WEST TO THE EAST TONIGHT WHICH WILL CONTINUE THROUGH THE DAY MONDAY. IT IS DIFFICULT TO TELL WHAT IMPACT RECENT SNOW PACK WILL HAVE ON TEMPS TONIGHT AND MONDAY WITH PAST EVENTS WARMING MUCH FASTER THAN ORIGINALLY INDICATED. FOR NOW I THINK OUR LOWS SHOULD COOL TO LOW TO MID TEENS FOR MOST LOCATIONS DESPITE WARMING AIRMASS. H85 TEMPS ON MON WOULD SUPPORT HIGHS IN THE MID 50S TO AROUND 60F UNDER IDEAL MIXING. TO ACCOUNT FOR SNOW I KEPT HIGH FORECAST MON ABOUT 5-10F COOLER RANGING FROM UPPER 40S IN THE NORTH TO MID 50S IN THE SOUTH WHERE LESS SNOW FELL. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 143 PM MDT SUN MAR 10 2013 LONG TERM FORECAST CONCERNS ARE THE POTENTIAL FOR FLURRIES MONDAY NIGHT AND THE POSSIBILITY OF PRECIPITATION DURING NEXT WEEKEND. NORTHWEST FLOW ALOFT OVER THE FORECAST AREA AS THE RIDGE AMPLIFIES OVER THE WESTERN UNITED STATES WILL CARRY A SHORT WAVE TROUGH THROUGH THE CENTRAL HIGH PLAINS REGION OVERNIGHT MONDAY NIGHT. THERE MAY BE A FEW FLURRIES ASSOCIATED WITH THIS WAVE AS MID AND LOWER LEVEL MOISTURE INCREASES. WINDS MAY ALSO BE GUSTY OVERNIGHT AND INTO THE DAY ON TUESDAY AS SUBSIDENCE BEHIND THIS WEAK WAVE HELPS MIX STRONGER WINDS TO THE SURFACE. DRY CONDITIONS WILL PERSIST THROUGH THE REMAINDER OF THE WORK WEEK AS THE BROAD RIDGE OVER THE WESTERN UNITED STATES MOVES EASTWARD FROM THE INTERMOUNTAIN REGION TO THE ROCKIES AND HIGH PLAINS. THE RIDGE WILL BEGIN TO FLATTEN THURSDAY NIGHT AND FRIDAY AS A SERIES OF WEAKER SHORT WAVE TROUGHS BEGINS TO MOVE INTO THE WEST COAST AND ACROSS THE TOP OF THE RIDGE. MUCH WARMER THAN NORMAL TEMPERATURES ARE EXPECTED ACROSS THE FORECAST AREA THURSDAY AND FRIDAY. THE FLOW FLATTENS ACROSS THE UNITED STATES TOWARDS THE END OF THE WEEK AND INTO THE WEEKEND FOR A MORE PROGRESSIVE PATTERN. BETWEEN FRIDAY NIGHT AND SUNDAY THE GFS AND ECMWF BEGIN TO DIVERGE IN THERE INDIVIDUAL HANDLING OF SUBSEQUENT SHORT WAVES AND THE LARGER SCALE UPPER TROUGH MOVING INTO THE WESTERN UNITED STATES. DEPENDING UPON WHICH SOLUTION PANS OUT...THE CENTRAL HIGH PLAINS REGION COULD SEE COOLER TEMPERATURES...ALTHOUGH STILL WARMER THAN AVERAGE FOR THIS TIME OF YEAR...ALONG WITH SOME LIGHT SHOWERS MOVING ACROSS THE AREA ON SATURDAY...OR COOLER TEMPERATURES AND A FEW SPRINKLES ACROSS PORTIONS OF THE AREA ON SUNDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1109 PM MDT SUN MAR 10 2013 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. AFTER THE SUN COMES THE WINDS WILL BECOME NORTHWEST AND GUSTY AS A SURFACE TROUGH MOVES THROUGH THE AREA. WINDS WILL BECOME MUCH LIGHTER NEAR 00Z. EVEN THOUGH CONDITIONS WILL REMAIN VFR...CEILINGS WILL LOWER AND THICKEN. TOWARD THE END OF THIS PERIOD OR JUST AFTER...THERE WILL BE THE POSSIBILITY OF VERY LIGHT SNOW. SINCE IT IS AT THE END OF THIS PERIOD...CHOSE NOT TOO MENTION IT AT THIS TIME. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...DR LONG TERM...LOCKHART AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
105 AM EDT MON MAR 11 2013 ...Updated Aviation Discussion... .Forecast Update... Issued at 1005 PM EST Sun Mar 10 2013 Rain band is progressing slowly eastward across the western forecast area. Dewpoints have been slow to come up over the eastern half, but that should change as this batch of moisture aloft saturates the lower levels. Expect the rain shield to expand as we get a low level surge of winds overnight. Latest RAP indicating between 45-55 knots at 2 kft. Diffluent flow aloft will combine with these low level winds to create additional rains. Did not make any changes to the pops, but did bring the near term grids closer to current values. These changes are transparent in the zones, so not sending out a zone update at this point. Still looking for areal averages for rain between an inch and an inch and a half by Monday evening. && .Short Term (Now - Monday Night)... Issued at 300 PM EDT Sun Mar 10 2013 The approaching surface low continues to strengthen as the upper-level trough is amplifying over the central CONUS. The surface low, currently across the Middle Mississippi River Valley, will move north-northeast to Lake Michigan by Monday morning. This more northward movement of the surface low will cause the frontal boundary to slowly progress eastward. Under cloudy skies, a few sprinkles were present this morning. This quickly dissipated and cloud cover began to break up by late morning. This has allowed temperatures to range from the mid 60s to low 70s early this afternoon, with a little more warming possible. Southerly winds have also increased across the region, in response to the strengthening pressure gradient. Gusts have reached the low to mid 30 mph range, mainly across our southwest CWA (Bowling Green region) and believe a few more hours of gusts similar to this will be possible. Lighter wind gusts will be possible across the east and northeast forecast area. By this evening, the frontal boundary will approach from the west. Widespread rain, moderate at times, will move across the western forecast area late this evening, the central forecast area during the early morning hours to about daybreak, and across the eastern forecast area from about daybreak through midday Monday. Expect precipitation efficient rainfall, as warm-cloud depths range between 8-9K feet, total PWs range between 1 and 1.2 inches, and sub-cloud layer relative humidity will be 70+ percent. Still looking for 0.75-1.4 inches of rainfall for overall QPF, with the higher amounts being across south-central Kentucky. This should not cause may issues, with just some nuisance ponding/flooding and rises on area rivers and streams. Some low-top showers could develop on the back side of the departing main precip shield Monday afternoon and exit the eastern forecast area during the evening hours. Will continue PoPs Monday afternoon and trend them back from west to east, ending PoPs around midnight in the east. Still appears showers could mix down some stronger, sub-severe winds. So, winds of 40 mph are possible, especially with already strong gradient winds. Strong gusty winds will subside a bit tonight and transition to westerly Monday afternoon and evening, as the front pushes through the forecast area. Expect non-diurnal temperature trends Sunday night and Monday as colder air filters southeast across the forecast area. Temperatures will be quite mild tonight, with readings ranging from the low to mid 50s. Temperatures will trend cooler from northwest to southeast through the day Monday, with generally low 40 in the northwest to around 50 in the southeast expected by early Monday evening. Temperatures will continue to cool Monday night, with lows in the lower 30s anticipated. .Long Term (Tuesday Night through Sunday)... Issued at 340 PM EDT Sun Mar 10 2013 Tuesday Night through Thursday Night... The medium range models are in fairly decent agreement for the middle of the week. The multi-model consensus is in agreement that a fairly stout upper trough will push through the region around mid-week bringing colder than normal temperatures back into the region. Within the upper trough, the models continue to struggle with bringing a mid-level vorticity max through the base of the trough. Using the consensus mean, it appears that this feature will most likely pass to our north and just bring some clouds down into the region Wednesday afternoon and evening. The upper trough will shift to the east on Thursday as some mid-level ridging builds to the west of the area. We will remain in a northwesterly flow aloft and will be watching for another mid-level vort max to swing through the region Thursday night. The timing of this vort max is very much in question as the deterministic models continue to have timing issues. Yesterday`s solutions showed the GFS being more progressive and faster, but today`s solutions show a faster Euro and slower GFS. For now, will keep some low chc PoPs in for Thursday night until some better forecast/model continuity. As for temperatures, the multi-model consensus has trended a little cooler over the last 24 hours. Therefore, it appears that going a little cooler on temperatures is probably a good bet at this point, but nothing too earth shattering. Lows Tuesday and Wednesday night will cool into the 20s. Highs Tuesday will probably only warm into the lower 40s in the north with lower-middle 40s in the south. A little bit of a warm up is expected Thursday with readings warming into the upper 40s in the north and lower 50s in the south. Lows Thursday night look to cool back into the mid 30s. Friday through Sunday... The long term portion of the forecast can be summed up as a low confidence forecast at best given the large amount of spread in today`s deterministic guidance. Utilizing an average of the multi-model consensus, the upper ridge over the east looks to eventually get replaced with a broad trough as we get toward the end of the forecast period. The Euro and GFS both handle the mid-level wave differently and with different speeds. The GFS lets the wave slide east and results in a quasi-stationary boundary remaining over the region from this weekend and into next. On the other hand, the Euro has been trending with pushing the system on through with the boundary setting up to our south with a more significant system developing just beyond the forecast period. Interestingly enough, the pattern is almost reminiscent of the system that passed through the Mid-Atlantic last week...though the Euro solutions are a little more to the south of last weeks track. For now, plan on leaving conditions partly to mostly cloudy through the period. Will maintain some low chance PoPs in the forecast but hold off on making more significant adjustments until some better forecast convergence emerges. Temperatures are equally challenging as well. The overall pattern does support above normal temperatures with highs on Friday warming into the upper 50s to the lower 60s. Saturday could be a bit warmer with readings in the lower to middle 60s. Depending on the eventual frontal position, we trended temperatures back a bit on Sunday and have gone with a more consensus blend here which results in temperatures in the middle to upper 50s. Overnight lows through the period will likely average in the 40s. && .Aviation (06Z TAF Issuance)... Issued at 104 AM EDT Sun Mar 11 2013 Surface low is now over the lower Great Lakes with upper level low over southern Iowa. A cold front extends southward from the surface low along the middle Mississippi River Valley, and will slowly push east toward the TAF sites through the overnight. Widespread rain showers are now filtering across the SDF/BWG terminal and will continue to do so through the overnight, however conditions should stay generally VFR, outside of the heaviest showers where a brief drop to MVFR vis is possible. As we approach dawn, the frontal boundary will begin to move through, and with the lighter winds will come lower ceilings. Will stay above the MVFR/IFR threshold for now, but cannot rule it out at this point. Showery activity will persists through the early afternoon behind the front, as the upper level trough axis to the west begins to move through. Will return to VFR by early to mid afternoon with a gusty west wind between 10 and 20 mph and a few gusts around 25 mph. LEX will widespread rain onset toward dawn, with a brief drop into the MVFR category for visibilities through midday. Then by mid afternoon, front moves through with low MVFR ceilings and light rain shower activity persisting into the early evening hours. Conditions should return to VFR by mid evening with a steady west wind. One other note, decided to let low level wind shear mention go as soundings across the area do not show much of a low level inversion and low level winds in the 1000-2000 foot range are marginal at this point. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........RJS Short Term.......MJP Long Term........MJ Aviation.........BJS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
600 AM EDT MON MAR 11 2013 .SYNOPSIS... HIGH PRESSURE WILL RESIDE ALONG THE MID-ATLANTIC COAST TODAY. A COLD FRONT WILL APPROACH TONIGHT...AND THEN MOVE ACROSS THE AREA DURING THE MORNING AND EARLY AFTERNOON ON TUESDAY. AN UPPER TROUGH IS EXPECTED TO LINGER OVER THE NORTHEAST AND MID-ATLANTIC STATES THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... A LGT SE RETURN FLOW HAS DEVELOPED IN RESPONSE TO HIPRES SHIFTING OFF THE ERN SEABOARD. ONSHORE COMPONENT TO THE FLOW HAS ADVECTED MARINE LAYER INLAND ERY THIS MRNG. 11U-3.9U SAT IMAGERY SHOWS STRATUS DECK HAS ADVANCED WESTWARD TO ABOUT I-95 AT 07Z. FCST REGARDING INLAND PROGRESSION OF STRATUS DECK ERY THIS MRNG WAS IN BETWEEN THE HRRR AND NAM...WHICH HAVE BOTH CAPTURED THIS STRATUS EVENT WELL THUS FAR. THE HRRR DEVELOPS STRATUS AS FAR WEST AS IAD TO FDK TO EZF WHILE THE 00Z NAM TAKES IT AS FAR INLAND AS MRB BY SUNRISE. LOPRES WILL TRACK NEWD ACROSS THE UPPER MIDWEST TDA WHILE ATTENDANT COLD FRONT MOVES THRU THE OH VLY. DEEP SLY FLOW WITHIN PRE-FRONTAL WARM SECTOR BECOMES FURTHER ESTABLISHED TDA. TEMPS FCST IS COMPLEX TDA AMID VARIABLE CLOUD COVER TDA. GIVEN THE MID MARCH SUN ANGLE...THERE IS A POTENTIAL FOR STRATUS TO TAKE LONGER TO MIX OUT THAN MODELS FCST ESPECIALLY TOWARD THE CHSPK BAY. HAVE CUT DOWN MAX TEMPS SEVERAL DEGREES FROM BIAS-CORRECTED MET. ELSEWHERE...HI CLOUDS THIS MRNG WILL THICKEN/LOWER THRUOUT THE DAY AS LLVL ISENTROPIC LIFT DEVELOPS AHEAD OF THE COLD FRONT. HIRES MODEL GUIDANCE IN AGREEMENT WITH FRONTAL BAND OF PRECIP REMAINING WEST OF THE CWA TDA...BUT A FEW LGT SHOWERS MAY DEVELOPS OVER THE POTOMAC HIGHLANDS LATE THIS AFTN. 00Z NAM/GFS IN GOOD AGREEMENT WITH THE COLD FRONT CROSSING THE CENTRAL APPALACHIANS CLOSE TO MIDNIGHT. STEADIER SHOWERS SHOULD MOVE INTO THE MTS THIS EVE WHILE LIGHTER AND MORE SCATTERED ACTIVITY DEVELOPS EAST OF THE BLUE RIDGE. COLD FRONT IS EXPECTED TO CROSS THE BLUE RIDGE OVNGT WHILE WIDESPREAD SHOWERS SPREAD EWD. WENT WARM WITH MIN TEMPS TNGT AS SLY FLOW AHEAD OF THE FRONT PREVENTS TEMPS FROM DROPPING MUCH DURING THE NGT. && .SHORT TERM /TUESDAY/... COLD FRONT WILL MOVE ACROSS THE CWA TUESDAY...DURING THE MORNING WEST OF THE BLUE RIDGE AND THEN MIDDAY/EARLY AFTERNOON TOWARD THE INTERSTATE 95 CORRIDOR. PREFER A NAM/SREF TIMING FOR FROPA/PRECIP ALTHOUGH GFS/ECMWF AREN/T MUCH DIFFERENT. THIS SHOULD ALLOW SHOWERS TO TAPER OFF ACROSS THE INTERSTATE 95 CORRIDOR BY EARLY AFTERNOON. TOTAL RAINFALL LOOKS TO BE ON THE ORDER OF 1/2 TO 3/4 OF AN INCH ACROSS THE CWA. IF SHOWERS END AS FORECAST AND PARTIAL CLEARING OCCURS LATER IN THE AFTERNOON...THEN MAXIMA SHOULD BE ABLE TO RECOVER AOA 60 DEG F ACROSS MUCH OF THE CWA /SAVE FOR HIGHER ELEVATIONS/. WITH THIS EXPECTATION AND CONSIDERING RECENT COLD BIASES FROM GUIDANCE...FAVORED THE WARMER BIAS CORRECTED MAV FOR MAXIMA ON TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... UPPER TROUGH/SHORTWAVE AND ASSOCIATED REINFORCING FRONT AT THE SURFACE MOVE THROUGH ON WEDNESDAY. THIS MAY PROMOTE LIGHT PRECIPITATION ACROSS THE NORTHWEST PORTION OF THE CWA...AND ALSO IS LIKELY TO BRING MOSTLY CLOUDY AND BLUSTERY CONDITIONS ACROSS THE CWA. COOLER AIR WILL MOVE IN BEHIND TUESDAY/S FROPA FOR WEDNESDAY...BUT COLDEST PERIOD OF THE STRETCH LOOKS TO BE THURSDAY/THURSDAY NIGHT IN THE WAKE OF THE REINFORCING BOUNDARY. MID-ATLANTIC REMAINS IN A WEST/NORTHWEST FLOW ALOFT INTO THE WEEKEND. BOTH GFS AND ECMWF INDICATE A WAVE BRINGING A CHANCE OF PRECIP SOMETIME IN THE SATURDAY THROUGH SUNDAY TIME FRAME. IT/S A LOW CONFIDENCE FORECAST ATTM AND CONTINUE LOW POPS FOR MAINLY SHRA DURING THE DAY AND SHSN AT NIGHT. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... STRATUS DECK CONTINUES TO ADVECT INLAND ERY THIS MRNG...RESULTING IN IFR CIGS. LATEST OBS AND 11U-3.9U SAT IMAGERY SHOWS STRATUS DECK HAS ADVANCED WESTWARD TO ABOUT DCA AS OF 0730Z. FCST REGARDING INLAND PROGRESSION OF STRATUS DECK ERY THIS MRNG WAS IN BETWEEN THE HRRR AND NAM /BOTH CAPTURED THIS STRATUS EVENT WELL THUS FAR/ WHICH REACHES IAD BEFORE SUNRISE BUT STAYS EAST OF MRB AND CHO. THE HRRR DEVELOPS STRATUS AS FAR WEST AS IAD TO FDK TO EZF WHILE THE 00Z NAM TAKES IT AS FAR INLAND AS MRB BY SUNRISE. 06Z TAFS REFLECTS EROSION OF STRATUS DECK FROM WEST TO EAST DURING THE MRNG. GIVEN THE MARCH SUN ANGLE...STRATUS MAY BE MORE STUBBORN TO ERODE THAN MODELS INDICATE. BWI AND MTN ARE MOST PRONE TO STRATUS HANGING UNTIL MIDDAY...AND POSSIBLY EVEN LATER. SHOWERS WILL OVERSPREAD THE TERMINALS FROM WEST TO EAST TNGT. SHOWERS AND CIG/VSBY RESTRICTIONS MAY DEVELOP BEFORE MIDNIGHT AT MRB/CHO AND OVNGT FARTHER EAST. LLWS ADDED TO TAFS FOR OVNGT AS 50 KT LOW-LEVEL JET CROSSES TERMINALS. GUIDANCE SUGGESTS IFR CONDITIONS ONGOING AT THE START OF TUESDAY. FLIGHT RESTRICTIONS WILL ASSOCIATED WITH SHOWERS MOVING THROUGH DURING THE MORNING PUSH. FROPA THAT BRINGS THE SHOWERS LOOKS TO OCCUR DURING MIDDAY/EARLY AFTERNOON HOURS AT THE HUBS...WITH A WIND SHIFT TO THE NORTHWEST. THIS SHOULD ALSO PROMOTE IMPROVING CONDITIONS TO VFR FOR THE AFTERNOON. REINFORCING COLD FRONT MOVES THROUGH ON WEDNESDAY WITH THE POTENTIAL FOR GUSTY WINDS. && .MARINE... SELY WINDS INCREASE THIS MRNG WHILE HIPRES MOVES OFFSHORE. WINDS BECOME MORE SLY THIS AFTN AND TNGT AS A COLD FRONT APPROACHES FROM THE WEST. SCA STARTS LATE THIS AFTN FOR THE MAIN STEM OF THE MD CHSPK BAY AND LOWER TIDAL POTOMAC RVR...WHICH ARE MOST PRONE TO SLY CHANNELING. SCA IN EFFECT FOR ALL WATERS TNGT. SCA HAS BEEN EXTENDED OVER THE MD CHESAPEAKE BAY AND LOWER TIDAL POTOMAC RIVER TUESDAY MORNING FOR ONGOING GUSTY/CHANNELLING SOUTHERLY FLOW. COLD FRONT MOVES EAST OF THE BAY DURING THE EARLY AFTERNOON HOURS...WITH A WIND SHIFT TO THE NORTHWEST. REINFORCING FRONT MOVES THROUGH WEDNESDAY...WITH SCA CONDITIONS LIKELY TO RETURN. && .TIDES/COASTAL FLOODING... WITH PERSISTENT SELY FLOW...ANOMALIES REMAIN AT OR JUST BELOW 2 FT THIS MRNG. ANOMALIES MAY INCREASE A BIT MORE TDA WITH SELY FLOW EXPECTED TO INCREASE. IF ANOMALIES DO INCREASE A BIT MORE...THAN ANNAPOLIS WOULD APPROACH MODERATE FLOOD STAGE. A COASTAL FLOOD WARNING FOR ANNE ARUNDEL COUNTY IS IN EFFECT THRU THIS EVE ACCORDINGLY. A COASTAL FLOOD ADVISORY WILL CONTINUE INTO TDA ALONG THE REMAINDER OF THE WRN SHORE OF THE MD CHSPK BAY AND THE TIDAL POTOMAC RVR. WILL LIKE TO MONITOR HOW ANOMALIES RESPOND TDA BEFORE EXTENDING THE WRNG OR ISSUING A WATCH FOR ANNE ARUNDEL SINCE CONFIDENCE IN REACHING MODERATE THRESHOLD IS TOO LOW TO ISSUE ATTM. CONFIDENT ON ADVISORY LEVEL /MINOR/ FLOODING CONTINUING INTO TUESDAY. COLD FRONT MOVES THROUGH THE BAY BY EARLY AFTERNOON TUESDAY. NORTHWEST WINDS BEHIND THE FRONT SHOULD HELP TO BRING LOWER WATER LEVELS THEREAFTER...HOWEVER HOW QUICKLY WATER LEVELS LOWER WILL DETERMINE WHETHER OR NOT ADVISORIES MAY CONTINUE FOR THE SUBSEQUENT HIGH TIDE CYCLE LATER TUESDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR DCZ001. MD...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR MDZ007- 011-013-016>018. COASTAL FLOOD WARNING UNTIL MIDNIGHT EDT TONIGHT FOR MDZ014. VA...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR VAZ052>055-057. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 1 PM EDT TUESDAY FOR ANZ530-531-538>541. SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EDT TUESDAY FOR ANZ532>534-537-542-543. SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 5 AM EDT TUESDAY FOR ANZ535. SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 5 AM EDT TUESDAY FOR ANZ536. && $$ SYNOPSIS...JRK/BPP NEAR TERM...JRK SHORT TERM...BPP LONG TERM...BPP AVIATION...JRK/BPP MARINE...JRK/BPP TIDES/COASTAL FLOODING...JRK/BPP
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
422 AM EDT MON MAR 11 2013 .SYNOPSIS... A COLD FRONT WILL SLOWLY MOVE ACROSS THE MIDWEST TODAY. EXPECT RAIN TO OVERSPREAD THE REGION LATE TODAY AND TONIGHT. BELOW NORMAL TEMPERATURES WILL RETURN BY WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AREA OF SPRINKLES...ASSOCIATED WITH SHORTWAVE OVER CENTRAL OHIO...IS MOVING NORTHWARD TOWARD LAKE ERIE. LATEST MODEL DATA KEEPS THIS SHORTWAVE TO THE NORTH AND WEST FOLLOWING THE STRONG SOUTHERLY FLOW ALOFT. BROAD AREA OF HIGH CLOUDS WILL COVER THE AREA THROUGH THE MORNING HOURS. CLOUDS WILL LOWER THIS AFTERNOON FROM THE WEST...AS SLOW MOVING FRONT APPROACHES. ABOVE AVE CONFIDENCE ON SLOWER FORECAST TODAY. LATEST HIRES MODELS ARE IN GOOD AGREEMENT WITH OP MODELS THAT MAIN AREA OF RAIN WILL SLOWLY MOVE THROUGH THE WEST LATE THIS MORNING AND THROUGH THE AFTERNOON AND WILL NOT REACH THE EASTERN HALF UNTIL THIS EVE. AN ISO SHOWER OR SPRINKLES IS POSSIBLE AHEAD OF THE MAIN AREA. WITH AREA IN THE WARM SECTOR...TEMPS WILL RISE ABOVE NORMAL AGAIN TODAY. LAMP MODEL HAS DONE PRETTY WELL WITH WARM AIR MASS...SO WILL LEAN ON THAT FOR HIGHS TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... EXPTG SHRA WITH FROPA OVRNGT. COLD AIR ADVCTN WL BEGIN AFT FROPA WITH LOW CHCS FOR PCPN. CRITICAL THICKNESSES/PROFILES INDICATE SHRA MAY MIX WITH SHSN TUE. HIGH TEMPS ARE EXPD TO DROP BLO SEASONAL AVGS AGAIN TUE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... COLD NW FLOW AND AN UPR LVL TROF WL BRING INCRG SHSN CHCS TO THE RGN THRU WED. SFC HI PRES GRDLY BLDS IN THU AND THU NGT. A WK SFC LOW IS EXPD TO QUICKLY TRACK SEWD ACRS THE OH VLY RGN FRI...WITH A CHC FOR SHRA/SHSN MAINLY S OF PIT. A QUASI STNRY FNT IS EXPD TO SET UP ACRS THE OH/TN VLY RGNS OVR THE WK END...CONTG THE CHC FOR SHRA/SHSN MAINLY S OF PIT. TEMPS EXPD TO REMAIN BLO SEASONAL AVGS THRU THE PD. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... VFR WEA WL CONT THRU MONDAY...HOWEVER...LLWS WL BE A CONCERN LATE TNGT AND EARLY MONDAY AS DEEPENING LOW PRES DVLPS TWD THE WRN GREAT LAKES. LATEST NAM AND RAP MDL SNDINGS INDICATE SUFFICIENT ENHANCEMENTMENT OF THE LLVL JET TO ADD A WIND SHEAR MENTION FOR THE OVRNGT HRS IN ALL...BUT ERNMOST TAF SITES. THIS STRONG WARM ADVCTN REGIME SHOULD CAP THE BNDRY LYR...AND THUS LIMIT GUSTS ON MONDAY. 20 TO 25 KT SFC GUSTS WL SUFFICE FOR THE CURRENT PROGNOSIS. .OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/... THE CDFNT EXTENDING FM THE AFOREMENTIONED GREAT LAKES LOW IS FORECAST FOR A MONDAY NGT CROSSING OF THE UPR OH VALLEY. RESTRICTIONS IN SHRA SHOULD BE ANTICIPATED WITH THAT PASSAGE...AND IN THE COLD ADVCTN REGIME BEHIND A REINFORCING FRONT PROJECTED FOR TUESDAY. HIGH PRES IS EXPECTED TO RTN GENL VFR TO REGIONAL PORTS FOR LTR THURSDAY AND FRIDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
401 AM EDT MON MAR 11 2013 .SYNOPSIS... HIGH PRESSURE WILL RESIDE ALONG THE MID-ATLANTIC COAST TODAY. A COLD FRONT WILL APPROACH TONIGHT...AND THEN MOVE ACROSS THE AREA DURING THE MORNING AND EARLY AFTERNOON ON TUESDAY. AN UPPER TROUGH IS EXPECTED TO LINGER OVER THE NORTHEASTERN QUARTER OF THE COUNTRY THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... A LGT SE RETURN FLOW HAS DEVELOPED IN RESPONSE TO HIPRES SHIFTING OFF THE ERN SEABOARD. ONSHORE COMPONENT TO THE FLOW HAS ADVECTED MARINE LAYER INLAND ERY THIS MRNG. 11U-3.9U SAT IMAGERY SHOWS STRATUS DECK HAS ADVANCED WESTWARD TO ABOUT I-95 AT 07Z. FCST REGARDING INLAND PROGRESSION OF STRATUS DECK ERY THIS MRNG WAS IN BETWEEN THE HRRR AND NAM...WHICH HAVE BOTH CAPTURED THIS STRATUS EVENT WELL THUS FAR. THE HRRR DEVELOPS STRATUS AS FAR WEST AS IAD TO FDK TO EZF WHILE THE 00Z NAM TAKES IT AS FAR INLAND AS MRB BY SUNRISE. LOPRES WILL TRACK NEWD ACROSS THE UPPER MIDWEST TDA WHILE ATTENDANT COLD FRONT MOVES THRU THE OH VLY. DEEP SLY FLOW WITHIN PRE-FRONTAL WARM SECTOR BECOMES FURTHER ESTABLISHED TDA. TEMPS FCST IS COMPLEX TDA AMID VARIABLE CLOUD COVER TDA. GIVEN THE MID MARCH SUN ANGLE...THERE IS A POTENTIAL FOR STRATUS TO TAKE LONGER TO MIX OUT THAN MODELS FCST ESPECIALLY TOWARD THE CHSPK BAY. HAVE CUT DOWN MAX TEMPS SEVERAL DEGREES FROM BIAS-CORRECTED MET. ELSEWHERE...HI CLOUDS THIS MRNG WILL THICKEN/LOWER THRUOUT THE DAY AS LLVL ISENTROPIC LIFT DEVELOPS AHEAD OF THE COLD FRONT. HIRES MODEL GUIDANCE IN AGREEMENT WITH FRONTAL BAND OF PRECIP REMAINING WEST OF THE CWA TDA...BUT A FEW LGT SHOWERS MAY DEVELOPS OVER THE POTOMAC HIGHLANDS LATE THIS AFTN. 00Z NAM/GFS IN GOOD AGREEMENT WITH THE COLD FRONT CROSSING THE CENTRAL APPALACHIANS CLOSE TO MIDNIGHT. STEADIER SHOWERS SHOULD MOVE INTO THE MTS THIS EVE WHILE LIGHTER AND MORE SCATTERED ACTIVITY DEVELOPS EAST OF THE BLUE RIDGE. COLD FRONT IS EXPECTED TO CROSS THE BLUE RIDGE OVNGT WHILE WIDESPREAD SHOWERS SPREAD EWD. WENT WARM WITH MIN TEMPS TNGT AS SLY FLOW AHEAD OF THE FRONT PREVENTS TEMPS FROM DROPPING MUCH DURING THE NGT. && .SHORT TERM /TUESDAY/... COLD FRONT WILL MOVE ACROSS THE CWA TUESDAY...DURING THE MORNING WEST OF THE BLUE RIDGE AND THEN MIDDAY/EARLY AFTERNOON TOWARD THE INTERSTATE 95 CORRIDOR. PREFER A NAM/SREF TIMING FOR FROPA/PRECIP ALTHOUGH GFS/ECMWF AREN/T MUCH DIFFERENT. THIS SHOULD ALLOW SHOWERS TO TAPER OFF ACROSS THE INTERSTATE 95 CORRIDOR BY EARLY AFTERNOON. TOTAL RAINFALL LOOKS TO BE ON THE ORDER OF 1/2 TO 3/4 OF AN INCH ACROSS THE CWA. IF SHOWERS END AS FORECAST AND PARTIAL CLEARING OCCURS LATER IN THE AFTERNOON...THEN MAXIMA SHOULD BE ABLE TO RECOVER AOA 60 DEG F ACROSS MUCH OF THE CWA /SAVE FOR HIGHER ELEVATIONS/. WITH THIS EXPECTATION AND CONSIDERING RECENT COLD BIASES FROM GUIDANCE...FAVORED THE WARMER BIAS CORRECTED MAV FOR MAXIMA ON TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... UPPER TROUGH/SHORTWAVE AND ASSOCIATED REINFORCING FRONT AT THE SURFACE MOVE THROUGH ON WEDNESDAY. THIS MAY PROMOTE LIGHT PRECIPITATION ACROSS THE NORTHWEST PORTION OF THE CWA...AND ALSO IS LIKELY TO BRING MOSTLY CLOUDY AND BLUSTERY CONDITIONS ACROSS THE CWA. COOLER AIR WILL MOVE IN BEHIND TUESDAY/S FROPA FOR WEDNESDAY...BUT COLDEST PERIOD OF THE STRETCH LOOKS TO BE THURSDAY/THURSDAY NIGHT IN THE WAKE OF THE REINFORCING BOUNDARY. MID-ATLANTIC REMAINS IN A WEST/NORTHWEST FLOW ALOFT INTO THE WEEKEND. BOTH GFS AND ECMWF INDICATE A WAVE BRINGING A CHANCE OF PRECIP SOMETIME IN THE SATURDAY THROUGH SUNDAY TIME FRAME. IT/S A LOW CONFIDENCE FORECAST ATTM AND CONTINUE LOW POPS FOR MAINLY SHRA DURING THE DAY AND SHSN AT NIGHT. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... STRATUS DECK CONTINUES TO ADVECT INLAND ERY THIS MRNG...RESULTING IN IFR CIGS. LATEST OBS AND 11U-3.9U SAT IMAGERY SHOWS STRATUS DECK HAS ADVANCED WESTWARD TO ABOUT DCA AS OF 0730Z. FCST REGARDING INLAND PROGRESSION OF STRATUS DECK ERY THIS MRNG WAS IN BETWEEN THE HRRR AND NAM /BOTH CAPTURED THIS STRATUS EVENT WELL THUS FAR/ WHICH REACHES IAD BEFORE SUNRISE BUT STAYS EAST OF MRB AND CHO. THE HRRR DEVELOPS STRATUS AS FAR WEST AS IAD TO FDK TO EZF WHILE THE 00Z NAM TAKES IT AS FAR INLAND AS MRB BY SUNRISE. 06Z TAFS REFLECTS EROSION OF STRATUS DECK FROM WEST TO EAST DURING THE MRNG. GIVEN THE MARCH SUN ANGLE...STRATUS MAY BE MORE STUBBORN TO ERODE THAN MODELS INDICATE. BWI AND MTN ARE MOST PRONE TO STRATUS HANGING UNTIL MIDDAY...AND POSSIBLY EVEN LATER. SHOWERS WILL OVERSPREAD THE TERMINALS FROM WEST TO EAST TNGT. SHOWERS AND CIG/VSBY RESTRICTIONS MAY DEVELOP BEFORE MIDNIGHT AT MRB/CHO AND OVNGT FARTHER EAST. LLWS ADDED TO TAFS FOR OVNGT AS 50 KT LOW-LEVEL JET CROSSES TERMINALS. GUIDANCE SUGGESTS IFR CONDITIONS ONGOING AT THE START OF TUESDAY. FLIGHT RESTRICTIONS WILL ASSOCIATED WITH SHOWERS MOVING THROUGH DURING THE MORNING PUSH. FROPA THAT BRINGS THE SHOWERS LOOKS TO OCCUR DURING MIDDAY/EARLY AFTERNOON HOURS AT THE HUBS...WITH A WIND SHIFT TO THE NORTHWEST. THIS SHOULD ALSO PROMOTE IMPROVING CONDITIONS TO VFR FOR THE AFTERNOON. REINFORCING COLD FRONT MOVES THROUGH ON WEDNESDAY WITH THE POTENTIAL FOR GUSTY WINDS. && .MARINE... SELY WINDS INCREASE THIS MRNG WHILE HIPRES MOVES OFFSHORE. WINDS BECOME MORE SLY THIS AFTN AND TNGT AS A COLD FRONT APPROACHES FROM THE WEST. SCA STARTS LATE THIS AFTN FOR THE MAIN STEM OF THE MD CHSPK BAY AND LOWER TIDAL POTOMAC RVR...WHICH ARE MOST PRONE TO SLY CHANNELING. SCA IN EFFECT FOR ALL WATERS TNGT. SCA HAS BEEN EXTENDED OVER THE MD CHESAPEAKE BAY AND LOWER TIDAL POTOMAC RIVER TUESDAY MORNING FOR ONGOING GUSTY/CHANNELLING SOUTHERLY FLOW. COLD FRONT MOVES EAST OF THE BAY DURING THE EARLY AFTERNOON HOURS...WITH A WIND SHIFT TO THE NORTHWEST. REINFORCING FRONT MOVES THROUGH WEDNESDAY...WITH SCA CONDITIONS LIKELY TO RETURN. && .TIDES/COASTAL FLOODING... WITH PERSISTENT SELY FLOW...ANOMALIES REMAIN AT OR JUST BELOW 2 FT THIS MRNG. ANOMALIES MAY INCREASE A BIT MORE TDA WITH SELY FLOW EXPECTED TO INCREASE. IF ANOMALIES DO INCREASE A BIT MORE...THAN ANNAPOLIS WOULD APPROACH MODERATE FLOOD STAGE. A COASTAL FLOOD WARNING FOR ANNE ARUNDEL COUNTY IS IN EFFECT THRU THIS EVE ACCORDINGLY. A COASTAL FLOOD ADVISORY WILL CONTINUE INTO TDA ALONG THE REMAINDER OF THE WRN SHORE OF THE MD CHSPK BAY AND THE TIDAL POTOMAC RVR. WILL LIKE TO MONITOR HOW ANOMALIES RESPOND TDA BEFORE EXTENDING THE WRNG OR ISSUING A WATCH FOR ANNE ARUNDEL SINCE CONFIDENCE IN REACHING MODERATE THRESHOLD IS TOO LOW TO ISSUE ATTM. CONFIDENT ON ADVISORY LEVEL /MINOR/ FLOODING CONTINUING INTO TUESDAY. NW FLOW BHD FNT SHUD ALLEVIATE CSTL FLOOD CONCERNS...BUT WE WL SEE HOW QUICKLY THAT WL FOLLOW. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR DCZ001. MD...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR MDZ007- 011-013-016>018. COASTAL FLOOD WARNING UNTIL MIDNIGHT EDT TONIGHT FOR MDZ014. VA...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR VAZ052>055-057. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 1 PM EDT TUESDAY FOR ANZ530-531-538>541. SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EDT TUESDAY FOR ANZ532>534-537-542-543. SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 5 AM EDT TUESDAY FOR ANZ535. SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 5 AM EDT TUESDAY FOR ANZ536. && $$ SYNOPSIS...JRK/BPP NEAR TERM...JRK SHORT TERM...BPP LONG TERM...BPP AVIATION...JRK/BPP MARINE...JRK/BPP TIDES/COASTAL FLOODING...JRK/BPP/HTS
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
138 AM EDT MON MAR 11 2013 .SYNOPSIS... A COLD FRONT WILL SLOWLY MOVE ACROSS THE MIDWEST TODAY. EXPECT RAIN TO OVERSPREAD THE REGION LATE TODAY AND TONIGHT. BELOW AVERAGE TEMPERATURES WILL RETURN BY WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... LITTLE CHANGE TO OVERNIGHT. MADE MINOR ADJUSTMENTS TO TEMPS AND CLOUD COVER. MODELS ARE IN GOOD AGREEMENT SLOWLY THE ONSET OF RAIN TODAY. WILL HOLD OF THE MENTION IN THE WESTERN HALF UNTIL THE AFTERNOON...WITH RAIN NOT REACHING THE EASTERN HALF UNTIL THIS EVE. EXPECT ANOTHER DAY OF ABOVE NORMAL TEMPS WITH SOUTHERLY WINDS STRENGTHENING AHEAD OF THE SFC FRONT. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... EXPTG SHRA WITH FROPA OVRNGT. COLD AIR ADVCTN WL BEGIN AFT FROPA WITH LOW CHCS FOR PCPN. CRITICAL THICKNESSES/PROFILES INDICATE SHRA MAY MIX WITH SHSN TUE. HIGH TEMPS ARE EXPD TO DROP BLO SEASONAL AVGS AGAIN TUE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... COLD NW FLOW AND AN UPR LVL TROF WL BRING INCRG SHSN CHCS TO THE RGN THRU WED. SFC HI PRES GRDLY BLDS IN THU AND THU NGT. A WK SFC LOW IS EXPD TO QUICKLY TRACK SEWD ACRS THE OH VLY RGN FRI...WITH A CHC FOR SHRA/SHSN MAINLY S OF PIT. A QUASI STNRY FNT IS EXPD TO SET UP ACRS THE OH/TN VLY RGNS OVR THE WK END...CONTG THE CHC FOR SHRA/SHSN MAINLY S OF PIT. TEMPS EXPD TO REMAIN BLO SEASONAL AVGS THRU THE PD. && .AVIATION /05Z MONDAY THROUGH FRIDAY/... VFR WEA WL CONT THRU MONDAY...HOWEVER...LLWS WL BE A CONCERN LATE TNGT AND EARLY MONDAY AS DEEPENING LOW PRES DVLPS TWD THE WRN GREAT LAKES. LATEST NAM AND RAP MDL SNDINGS INDICATE SUFFICIENT ENHANCEMENTMENT OF THE LLVL JET TO ADD A WIND SHEAR MENTION FOR THE OVRNGT HRS IN ALL...BUT ERNMOST TAF SITES. THIS STRONG WARM ADVCTN REGIME SHOULD CAP THE BNDRY LYR...AND THUS LIMIT GUSTS ON MONDAY. 20 TO 25 KT SFC GUSTS WL SUFFICE FOR THE CURRENT PROGNOSIS. .OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/... THE CDFNT EXTENDING FM THE AFOREMENTIONED GREAT LAKES LOW IS FORECAST FOR A MONDAY NGT CROSSING OF THE UPR OH VALLEY. RESTRICTIONS IN SHRA SHOULD BE ANTICIPATED WITH THAT PASSAGE...AND IN THE COLD ADVCTN REGIME BEHIND A REINFORCING FRONT PROJECTED FOR TUESDAY. HIGH PRES IS EXPECTED TO RTN GENL VFR TO REGIONAL PORTS FOR LTR THURSDAY AND FRIDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
742 PM EDT TUE MAR 12 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 408 PM EDT TUE MAR 12 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF CENTERED OVER THE GREAT LKS BTWN UPR RDGS ALONG THE W COAST AND OFF THE E COAST. WITH DEEP CYC NW FLOW...ABUNDANT MSTR SHOWN ON THE 12Z GRB RAOB...AND H85 TEMPS IN THE -13C TO -16C RANGE...SHSN HAVE BEEN COMMON OVER THE CWA TODAY UNDER CLDY SKIES...ESPECIALLY NEAR LK SUP IN AREAS FAVORED BY THE NW LLVL FLOW. THE SN HAS BEEN RATHER FLUFFY AS MODEL SDNGS INDICATE THE DGZ IS SEVERAL THOUSAND FEET DEEP GIVEN FVRBL H85 TEMPS. THERE IS A SHRTWV DROPPING SEWD THRU MN ACCOMPANIED BY A FAIRLY WELL DEFINED TROF AT H85-7. UPSTREAM OBS AT GRAND MARAIS ON THE MN NORTH SHORE AND AT THUNDER BAY IN ONTARIO INDICATE SOME HEAVIER SHSN ACCOMPANY THIS TROF PASSAGE FARTHER TO THE E-SE AWAY FM DRIER AIR SHOWN ON THE 12Z INL/YPL RAOBS. APRCHG FCST ISSUANCE... SOME OF THE HEAVIER SHSN HAVE ARRIVED OVER THE WRN COUNTIES. CMX HAS REPORTED VSBY DOWN TO 1/4SM AT TIMES...AND REPORTS FM GOGEBIC COUNTY INDICATE AS MUCH AS 5 INCHES OF SN FELL THERE THRU 18Z. LATE THIS AFTN/TNGT...AS SHRTWV IN MN DIGS SEWD...GUIDANCE SHOWS PRONOUNCED H85 WSHFT ASSOCIATED WITH TROF PASSAGE AS WELL AS AREA OF H85-5 QVECTOR CNVGC CROSSING THE CWA NW-SE. EXPECT SHSN TO INCRS IN INTENSITY WITH THIS ENHANCED SUPPORT IN PRESENCE OF DEEP MSTR. FCST SDNGS CONTINUE TO SHOW UVV FOCUSED IN THE DGZ...SO EXPECT HI SN/ WATER RATIOS AOA 20:1. LATER TNGT IN THE WAKE OF THE TROF PASSAGE... DEEP LYR QVECTOR DVGC/SUBSIDENCE IN THE WAKE OF THE SHRTWV/TROF WL CONSPIRE TO LOWER INVRN BASES DOWN TO 2-3K FT AGL. WITH ARRIVAL OF LLVL DRY AIR SHOWN ON THE 12Z INL/YPL RAOBS...EXPECT LES TO DIMINISH FAIRLY STEADILY AFT 06Z. OVERALL...SHIFTING WINDS FM NW TO N AND LIMITED 6-9HR WINDOW OR SO FOR HEAVIER SHSN WL LIMIT TOTAL SN FALL...SO EXPECT SN TOTALS TO REMAIN WITHIN ADVY LIMITS DESPITE FVRBL SN/WATER RATIOS. THGE ONLY EXCEPTION IS OVER THE FAR W...WHERE SOME HEAVY SN FELL DURING THE AFTN AS NOTED ABV. SINCE THERE WL BE PERIODS OF +SHSN THRU THIS EVNG IN THAT AREA WITH SOME FOCUSED LLVL CNVGC IN FVRBL CYC NNW FLOW...OPTED TO UPGRADE ADVY TO A WARNING FOR GOGEBIC/ONTONAGON COUNTIES. ALSO EXTENDED ADVY OVER THE ERN ZNS THRU 12Z GIVEN MORE PERSISTENT FORCING/DEEPER MSTR THERE. WED...AXIS OF MUCH DRIER AIR WITH H85 DEWPTS AS LO AS -40C AS WELL AS DEEP LYR QVECTOR DVGC/SUBSIDENCE UNDER STEADILY RISING H5 HGTS FOLLOWING SHIFT OF UPR TROF AXIS TO THE E WL RESULT IN MAINLY DRY WX AFTER LINGERING SHSN OVER MAINLY THE E DIMINISH IN THE MRNG. IN FACT...FCST SDNGS SUG SKIES MAY TURN MOSUNNY IN THE AFTN... ESPECIALLY NEAR LK SUP WITH A TENDENCY FOR CLRG OVER THE WATER UNDER STRENGTHENING LATE WINTER SUNSHINE. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 408 PM EDT TUE MAR 12 2013 TO START THE LONG TERM PERIOD...OVERVIEW OF LARGE SCALE FEATURES TROUGH OVER GREAT LAKES AND EASTERN CANADA WITH BROAD RIDGING EXTENDING WELL UPSTREAM INTO EASTERN PORTION OF PACIFIC OCEAN. FARTHER UPSTREAM TROUGHING IS PRESENT NORTH OF HAWAII. THAT TROUGH IS ESSENTIALLY EXTENSION OF TROUGHING RESIDING OVER NORTHERN PORTIONS OF CANADA ON NORTHERN PORTION OF WESTERN CONUS RIDGE. OVER TIME...TROUGH OVER GREAT LAKES SYNCS UP WITH TROUGHING OVER NORTHERN CANADA RESULTING IN FAST AND ACTIVE WEST-NORTHWEST FLOW ACROSS MOST OF THE CONUS THROUGH THE UPCOMING WEEKEND. TWO SHORTWAVES PROGGED TO DROP THROUGH IN THIS FLOW PATTERN INTO THIS WEEKEND. FIRST WAVE ALONG WITH WEAK SFC-H85 LOW-LEVEL WARM AIR ADVECTION GLANCES UPR LAKES TO WEST ON THURSDAY. WAVE IS DIGGING INTO THE MEAN TROUGH WHICH FAVORS MORE OF A SOUTH AND/OR WEST TRACK AND IS PRETTY PROGRESSIVE. ALSO LOOKS LIKE ANY UPPER JET SUPPORT REMAINS WEST OF UPR MICHIGAN. MODELS VARY WILDLY FROM SOUTH TO NORTH WHERE THE MOST QPF/SNOW IS EXPECTED. GEM-NH ON SOUTHERN EXTREME... TRACKING ACROSS IOWA...WHILE NAM IS OVER WESTERN UPR MICHIGAN. NAM IS ON NORTH EDGE OF EVEN SREF...SO IT IS CERTAINLY AN OUTLIER. GFS AND ECMWF IN BTWN...BUT ARE STILL MAINLY OVER WISCONSIN. SINCE THERE IS A SLIGHT EASTWARD TREND IN MODELS...WILL BRING CHANCE POPS OVER WESTERN CWA ON THURSDAY. OTHER ISSUE...PREVIOUSLY MENTIONED BY MID SHIFT...IS POSSIBLE FREEZING DRIZZLE LATER THURSDAY INTO THURSDAY NIGHT. BASED ON FORECAST SOUNDINGS...WI BORDER/SCNTRL...WILL HAVE BEST CHANCE SEEING THIS ONCE ANY SNOW DECREASES. ELSEWHERE...THINK TOO MUCH DRIER AIR IS AROUND BLO H85 TO HAVE IN THERE. SINCE AM NOT CERTAIN WHERE ULTIMATELY THE STEADIER SNOW SETS UP OVR CWA...IF IT DOES AT ALL...WILL KEEP FZDZ OUT OF FCST. COUPLE OF SUBTLE THINGS HAPPEN LATER THURSDAY INTO THURSDAY NIGHT THAT MAY HAVE LARGE IMPACT ON FORECAST FOR FRIDAY. ALL MODELS INDICATE STRONGER NORTHERN STREAM WAVE TRACKS WELL TO THE NORTH OVER NORTHWEST ONTARIO THURSDAY NIGHT. WE ARE GOOD THERE. TROUBLE IS THAT SAME MODELS DIFFER ON HOW FAR SOUTH TO BRING LOW-LEVEL COLD AIR IN WAKE OF SHORTWAVE BY FRIDAY MORNING. GEM-NH FARTHER SOUTH WITH COLD AIR AND TRENDS FROM GFS ALSO INDICATE FARTHER SOUTH LOW-LEVEL TEMPERATURE GRADIENT AT SFC-H85. ECMWF NOT AS COLD THOUGH. LOCATION OF TIGHTER LOW-LEVEL TEMPERATURE GRADIENT COULD PAVE THE WAY FOR WHERE HEAVIER QPF/SNOW SETS UP ON FRIDAY AS SHORTWAVE AND SFC-H85 LOWS MOVE IN FROM NORTHERN PLAINS. THIS SECOND SHORTWAVE IS MUCH STRONGER THAN ONE MOVING THROUGH 24 HR EARLIER AND HAS POTENTIAL TO BRING WIDESRPEAD SNOW TO UPPER LAKES ON FRIDAY. WHERE EVER LOW-LEVEL BAROCLINIC ZONE SETS UP THERE ARE ENHANCING FACTORS THAT MAY RESULT IN SWATH OF MODERATE TO HEAVY SNOW INCLUDING DIVERGENCE ALOFT FROM RIGHT ENTRANCE REGION OF JET STREAK DROPPING INTO GREAT LAKES FROM ONTARIO...DECENT MOISTURE ADVECTION WITH H7 MIXING RATIOS OVR 3G/KG...AND OVERALL STRENGTHENING SFC-H85 LOWS/LOW-LEVEL FLOW. ADVY LEVEL SNOWS CERTAINLY POSSIBLE. INCREASED POPS TO LIKELY OVER WEST AND SOUTH...WHERE MODEL AGREEMENT IS HIGHER THAT SNOW OCCURS. WWD DAY 3 GRAPHICS INDICATE UP TO 4 INCHES OVER WEST THIRD OF CWA ON FRIDAY. IF FARTHER NORTH ECMWF AND GEM-NH ARE CORRECT...THEN LIKELY POPS WILL BE NEEDED FOR MOST AREAS ON FRIDAY. AT FIRST GLANCE A MAINLY QUIET WEEKEND AS HIGH PRESSURE IS MAIN FEATURE OVER REGION. COULD BE RE-INFORCING SHOT OF COLDER AIR AND SOME DEEPER MOISTURE COME IN LATER SATURDAY AND SATURDAY NIGHT. GFS/ECMWF INDICATE INCREASE IN POPS DURING THAT TIME. KEPT CHANCY POPS IN ALONG LK SUPERIOR WITH ADDED POTENTIAL FOR LK EFFECT AS H85 TEMPS DROP INTO THE -15C TO -20C RANGE. RECORD SETTING WARMTH OF MID MARCH IN 2012 WILL BE BUT A DISTANT MEMORY COMPARED TO THE CHILL OF THIS YEAR. COOL AND ACTIVE PATTERN CONTINUES INTO EARLY NEXT WEEK...AND PROBABLY EVEN INTO LATER MARCH AS WELL. CERTAINLY NOT DONE WITH WINTER YET. DEEPER SHORTWAVE TROUGH EMERGES FROM TROUGHING OVER NORTHERN CANADA AND EVENTUALLY TRACKS ACROSS ROCKIES LATE IN THE WEEKEND. THIS TROUGH THEN DEEPENS ACROSS THE MIDDLE CONUS MONDAY AND MOVES INTO THE GREAT LAKES ON TUESDAY. DEEPENING LOW PRESSURE SYSTEM RESULTS WHICH DRAWS UP GULF MOISTURE AND COULD LEAD TO SIGNIFICANT SNOW SOMEWHERE UPPER MIDWEST THROUGH THE GREAT LAKES...INCLUDING UPR MICHIGAN. OVERALL THE ECMWF IS DEEPER AND FARTHER NORTH WITH SFC LOW...THOUGH LATEST RUN BACKED OFF WITH STRENGTH OF LOW. GFS IS MORE SUPPRESSED WITH TRACK OF SFC LOW. WPC...FORMALLY HPC...HAND DRAWN PROGS BTWN THE TWO WITH LOW MOVING ACROSS LOWER LAKES AND UPR MICHIGAN JUST ON THE FRINGE. CONSENSUS POPS ARE IN THE CHANCE RANGE WHICH IS FINE AT THIS POINT. GIVEN NORTHEAST WINDS AND COOLER AIR...INCREASED POPS CLOSER TO LK SUPERIOR. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 740 PM EDT TUE MAR 12 2013 PREVAILING LIFR CONDITIONS SHOULD LINGER THRU MUCH OF THE EVENING AT KCMX AND ESPECIALLY KIWD AS LAKE ENHANCED SNOW CONTINUES WITH DISTURBANCE/TROF PASSING ACROSS THE AREA. SIMILAR TO WHAT HAS HAPPENED OVER THE LAST FEW HRS...EXPECT FLUCTUATIONS TO IFR AT TIMES. AT KSAW...IFR CONDITIONS WILL CONTINUE THIS EVENING...THOUGH THERE MAY BE FLUCTUATIONS DOWN TO LIFR LATE EVENING AS WIND SHIFT TO A MORE NRLY DIRECTION IMPROVES UPSLOPE/LAKE ENHANCED SNOWFALL. SUBSIDENCE/STRONG DRYING IN THE WAKE OF THE TROF PASSAGE WILL RESULT IN CONDITIONS IMPROVING TO MVFR AT ALL 3 SITES OVERNIGHT. MAY SEE MVFR CIGS SCATTER OUT WED AFTN UNDER CONTINUED DRYING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 408 PM EDT TUE MAR 12 2013 UNDER THE TIGHTENING PRES GRADIENT IN THE WAKE OF A TROF PASSAGE THIS EVENING...EXPECT A N GALE UP TO 35 KTS OVER PORTIONS OF NCENTRAL LAKE SUP MUCH OF TONIGHT. FREEZING SPRAY WILL BE WIDESPREAD. AS THE GRADIENT WEAKENS LATE TONIGHT THRU WED...THE WINDS WILL GRADUALLY DIMINISH AND BACK TOWARD THE NW WITH APPROACH OF HI PRES FROM THE W. WINDS OF LESS THAN 20 KTS PERSIST INTO THURSDAY AS HIGH PRESSURE SLIDES ACROSS. SOUTHWESTERLY RETURN FLOW ON BACK SIDE OF HIGH MAY GET GUSTY OVER 25 KTS BY THU NIGHT. COLD FRONT SHIFTS THROUGH OVERNIGHT THURSDAY NIGHT WITH NORTHWEST WINDS TRYING TO REACH 30 KTS. NORTHERLY WINDS TO 25 KTS CONTINUE INTO FRI. WINDS DIMINISH THROUGH REST OF WEEKEND AS HIGH PRESSURE RETURNS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR MIZ006-007- 085. WINTER WEATHER ADVISORY UNTIL 2 AM EDT WEDNESDAY FOR MIZ001- 003>005-084. LAKE EFFECT SNOW WARNING UNTIL 2 AM EDT /1 AM CDT/ WEDNESDAY FOR MIZ002-009. LAKE SUPERIOR... GALE WARNING UNTIL 5 AM EDT WEDNESDAY FOR LSZ243-244-264. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...JLA AVIATION...ROLFSON MARINE...KC/JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
637 PM EDT MON MAR 11 2013 .UPDATE... ISSUED AT 636 PM EDT MON MAR 11 2013 PER WATER VAPOR IMAGERY...SHORTWAVE LIFTING N THRU WRN LWR MI IS LOOKING INCREASINGLY IMPRESSIVE...AND IR IMAGERY SHOWS RAPIDLY COOLING CLOUD TOPS THRU NRN LWR MI AS DEEP LAYER FORCING STRENGTHENS. AS A RESULT...RADAR IMAGERY SHOWS EXPANDING PCPN ACROSS NRN LWR MI. HAVE INCREASED POPS TO CATEGORICAL OVER THE FAR ERN FCST AREA FOR SEVERAL HRS THIS EVENING AS EXPANDING/INTENSIFYING PCPN SHIELD LIFTS N. COLUMN SHOULD RAPIDLY COOL...GIVING A QUICK TRANSITION FROM MOSTLY LIQUID TO SNOW AS PCPN ARRIVES. INCLUDED 1-2 INCH SNOW AMOUNTS ACROSS LUCE COUNTY...BUT WILL NEED TO MONITOR TRENDS CLOSELY OVER THE NEXT FEW HRS AS IT`S NOT OUT OF THE QUESTION THAT THIS COULD TURN INTO AN ADVY TYPE SNOW EVENT OVER THE FAR E GIVEN THE STRENGTHENING SHORTWAVE. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 426 PM EDT MON MAR 11 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW AN UPR TROF OVER CENTRAL AND ERN NAMERICA. NEGATIVELY TILTED CLOSED LO OVER THE LOWER GRT LKS IS TENDING TO LIFT TO THE NE AS ANOTHER SHRTWV DROPPING THRU SCENTRAL CANADA DIGS INTO THE NRN PLAINS. THE SFC LO ASSOCIATED WITH THIS DISTURBANCE HAS PUSHED TO NEAR MANISTIQUE AS OF MID AFTN. SFC TEMPS AT ISQ/ERY HAVE RISEN INTO THE MID/UPR 30S TO THE E OF THE SFC LO...AND THERE IS SOME FOG HERE WITH THE DRY AIR MOVING OVER LINGERING LLVL MSTR. THE ARRIVAL OF THE DRY SLOT ASSOCIATED WITH THE UPR LO HAS ENDED MOST OF THE PCPN EXCEPT OVER THE WRN COUNTIES... WHICH LIE UNDER THE DEFORMATION ZN ON THE CYC SIDE OF THE H7 LO TRACK. PERIODS OF SN HAVE BEEN MOST PERSISTENT IN THESE AREAS TDAY...WITH SN FALL RATES UP TO 0.5-0.75 INCH/HR. ALTHOUGH THE DRY SLOT HAS SWEPT THRU THE CNTRL COUNTIES...SOME -SN CONTINUES OVER MAINLY NCENTRAL MQT COUNTY WITH CYC UPSLOPE N WIND PROVIDING SUFFICIENT LIFT. ANOTHER AREA OF -SHRASN ASSOCIATED WITH THE DPVA/DEEP LYR QVECTOR CNVGC AHEAD OF THE UPR LO IS APRCHG THE SE COUNTIES...BUT PRESENCE OF LARGER SCALE DRY SLOT LOOKS TO BE LIMITING THE COVERAGE TO SCT -SHRASN. TO THE W...12Z YPL/INL RAOBS SHOW A DRIER/MORE STABLE AIRMASS IS PRESENT OVHD TO THE W OF THE DEFORMATION ZN IN MN...AND THERE IS LTL PCPN FALLING THERE. ALTHOUGH A FAIRLY IMPRESSIVE COMMA CLD APPEARS ASSOCIATED WITH THE SHRTWV DIGGING INTO THE NRN PLAINS...PCPN APPEARS TO BE CONFINED TO AN AREA NEAR LK WINNIPEG RIGHT UNDER THE COMMA HEAD. MAIN FCST CONCERNS TNGT ARE SN TRENDS/GOING HEADLINES. FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SHRTWV DIGGING INTO THE NRN PLAINS. TNGT...MODELS SHOW SFC LO LIFTING NEWD INTO SE ONTARIO TNGT...BUT CLOSED LO/DEEPER MSTR TENDING TO LINGER OVER THE UPR LKS DESPITE ARRIVAL OF DEEP LYR QVECTOR DVGC BY 06Z. AREA OF -SHRASN LIFTING NWD THRU LK MI AHEAD OF THE UPR LO WL IMPACT THE ERN ZNS THIS EVNG WITH AREAS OF FOG LINGERING THERE UNTIL SFC LO PASSES TO THE NE THIS EVNG AND COLDER AIR ARRIVES. SUSPECT LINGERING DEFORMATION ZN PCPN OVER THE WRN CWA WL SLOWLY DIMINISH WITH ARRIVAL OF THE NEGATIVE FORCING...SO ENDED THE GOING HEADLINES AS SCHEDULED 00Z TO 06Z FM SW TO NE. DOWNGRADED THE WARNINGS FOR BARAGA/MQT COUNTIES VALID THRU 0Z WITH BULK OF PCPN EXPECTED TO FALL FARTHER W ON CYC SIDE OF H7 LO TRACK. EVEN THOUGH THE STEADY SN WL TEND TO DIMINISH OVER THE W...CYC NW FLOW OF AIR/ARRIVAL OF COLDER AIR WITH H85 TEMPS PROGGED TO SINK AS LO AS -14C TO -15C BY 12Z TUE WL CAUSE NMRS SHSN TO PERSIST. BUT CONCERNED LO INVRN HGTS/DRY MID LVL AIR SHOWN ON THE 12Z INL/YPL RAOBS WL LIMIT THE COVERAGE/INTENSITY OF THE SHSN...SO WENT NO HIER THAN LIKELY POPS FOR NOW. TUE...DISTURBANCE MOVING THRU THE NRN PLAINS/ACCOMPANYING DEEP LYR QVECTOR CNVGC IS PROGGED TO MOVE TOWARD THE CWA...SO MAINTAINED GOING INCRSG POPS TO CATEGOCIAL NEAR LK SUP BY LATE AFTN WITH FAIRLY SHARP CYC NW FLOW ACTING AS AN ENHANCEMENT FACTOR IN THE PRESENCE OF DEEPER MSTR/H85 TEMPS NOT FAR FM -15C. SINCE FCST SDNGS SHOW THE DGZ SEVERAL THOUSAND FEET DEEP IN THE CONVECTIVE LYR...CONCERNED SOME ADVY INTENSITY LES MIGHT OCCUR LATER IN THE DAY...ESPECIALLY IN THE UPSLOPE AREAS OVER THE W. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 426 PM EDT MON MAR 11 2013 WITH AN UPPER LOW JUST E OF THE CWA AT 00Z WED AND A SFC TROUGH OVER LAKE SUPERIOR...850MB TEMPS WILL BE AROUND -14 WITH CYCLONIC NW-NNW LOW LEVEL WINDS. THESE CONDITIONS WILL BE FAVORABLE FOR LES TUE NIGHT...WITH WARMING TEMPS VERY DRY LOW LEVEL AIR MOVING IN WITH A SFC RIDGE LATE TUE NIGHT INTO WED NIGHT. EXPECT A RELATIVELY QUICK BURST OF MODERATE LES ALONG AND JUST BEHIND THE SFC TROUGH THAT MAY BRING A QUICK 2-4 INCHES OF SNOW OVER THE FAVORED HIGHER TERRAIN. WITH THE RATE THAT THE VERY DRY AIR MOVES IN LATE TUE NIGHT...LES WILL QUICKLY WEAKEN...AND SHOULD BE ALMOST COMPLETELY GONE BY 15Z WED /IF NOT A BIT EARLIER/. MODELS THEN INDICATE AN AREA OF INCREASED LOW LEVEL MOISTURE AND INCREASED LAKE INDUCED EQUILIBRIUM LEVELS MOVING ACROSS CENTRAL LAKE SUPERIOR ALONG A WEAK SFC TROUGH WED NIGHT. WILL KEEP SLIGHT CHANCE POPS E OF MARQUETTE AS CONDITIONS WILL STILL ONLY BE MARGINAL FOR LES. ELSEWHERE WED NIGHT...CLEARING OVER THE INTERIOR W SHOULD ALLOW MIN TEMPS TO FALL TO NEAR ZERO. A COUPLE OF SHORTWAVES LOOK TO MOVE NEARBY THU/THU NIGHT...BUT CONSENSUS OF MODELS PLACES BEST FORCING AND PRECIP N AND S OF THE CWA...SO WILL KEEP ANY POPS ON THE LOW SIDE. ANOTHER SHORTWAVE...BACKED UP BY THE LEFT EXIT REGION OF A 120+KT JET...MOVES THROUGH FRI INTO FRI NIGHT. MODEL VARY WITH TIMING...BUT GENERALLY AGREE ON OVERALL EXTENT/STRENGTH OF THE SYSTEM. MODELS PAINT A QUARTER TO A THIRD OF AN INCH OF QPF...AND THE BEST OMEGA LOOKS TO BE JUST BELOW AND INTO THE DGZ...WHICH SHOULD KEEP SNOW TO LIQUID RATIOS FROM GETTING TOO LOW. STILL DIFFICULT TO SAY GIVEN VOLATILE NATURE OF SHORTWAVES THAT FAR OUT...BUT COULD SEE A FEW INCHES OF SNOW ACROSS THE AREA. 850MB TEMPS AOB -14C AND N-NW FLOW BEHIND THE SYSTEM WOULD BRING SOME ADDITIONAL LES INTO SAT /AND POSSIBLY BEYOND BUT TOO UNCERTAIN IN ANY DETAILS THAT FAR OUT TO MENTION OR ADD TO THE FORECAST/. HIGHS TEMPS WILL BE IN THE 20S ON WED...WITH A WARM UP TO AROUND 30 ON THU AND INTO THE MID 30S ON FRI. TEMPS LOOK TO DECREASE GOING INTO THE WEEKEND AND EARLY NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 149 PM EDT MON MAR 11 2013 WINTER STORM STILL OVER NORTHERN UPR MICHIGAN...SO EXPECT POOR FLYING CONDITIONS TO CONTINUE. NNE WINDS TURN NNW TONIGHT. HEAVIER SNOW WITH MID-LEVEL LOW WILL CONTINUE AT IWD AND CMX INTO THIS EVENING. THEN...LK EFFECT SNOWS WITH IFR VSBY AND MVFR CIGS SHOULD CONTINUE THROUGH REST OF TAF PERIOD DUE TO LINGERING COOL AND MOIST FLOW THROUGH LOWEST 5KFT. AT SAW...CONDITIONS WILL IMPROVE STEADILY THROUGH LATE AFTN THROUGH TONIGHT AS HEAVIER SNOW REMAINS WEST THIS AFTN AND LK EFFECT DEVELOPING TONIGHT WILL NOT BE AS FAVORABLE WITH MORE OF A NW COMPONENT TO WIND. EVEN SO...PLENTY OF LINGERING MOISTURE AND CYCLONIC LOW-LEVEL WINDS SHOULD RESULT IN MVFR CONDITIONS INTO TUESDAY. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 426 PM EDT MON MAR 11 2013 EXPECT SLOWLY DIMINISHING NNE WINDS TO BACK TO THE NW TNGT INTO TUE AS SFC LO OVER ERN UPR MI THIS EVNG MOVES NEWD THRU ONTARIO TOWARD JAMES BAY. EVEN THOUGH WINDS WL BE SLOWLY DIMINISHING...THE ARRIVAL OF COLDER AIR WL RESULT IN SOME FREEZING SPRAY. A TROUGH WILL MOVE THROUGH LATE TUESDAY AND TUESDAY NIGHT...CAUSING WINDS TO GUST NEAR 35KTS OVER CENTRAL AND EASTERN LAKE SUPERIOR. WINDS RELAX WEDNESDAY AND WEDNESDAY NIGHT AS A RIDGE MOVES THROUGH. BEHIND THE RIDGE. WINDS WILL REMAIN BELOW 20KTS THROUGH THE REST OF THE WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 11 PM EDT THIS EVENING FOR MIZ004- 005. WINTER STORM WARNING UNTIL 11 PM EDT THIS EVENING FOR MIZ002-084. WINTER STORM WARNING UNTIL 2 AM EDT TUESDAY FOR MIZ003. WINTER WEATHER ADVISORY UNTIL 2 AM EDT TUESDAY FOR MIZ001. WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MIZ009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...ROLFSON SHORT TERM...KC LONG TERM...TITUS AVIATION...JLA MARINE...KC/TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
430 PM EDT MON MAR 11 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 426 PM EDT MON MAR 11 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW AN UPR TROF OVER CENTRAL AND ERN NAMERICA. NEGATIVELY TILTED CLOSED LO OVER THE LOWER GRT LKS IS TENDING TO LIFT TO THE NE AS ANOTHER SHRTWV DROPPING THRU SCENTRAL CANADA DIGS INTO THE NRN PLAINS. THE SFC LO ASSOCIATED WITH THIS DISTURBANCE HAS PUSHED TO NEAR MANISTIQUE AS OF MID AFTN. SFC TEMPS AT ISQ/ERY HAVE RISEN INTO THE MID/UPR 30S TO THE E OF THE SFC LO...AND THERE IS SOME FOG HERE WITH THE DRY AIR MOVING OVER LINGERING LLVL MSTR. THE ARRIVAL OF THE DRY SLOT ASSOCIATED WITH THE UPR LO HAS ENDED MOST OF THE PCPN EXCEPT OVER THE WRN COUNTIES... WHICH LIE UNDER THE DEFORMATION ZN ON THE CYC SIDE OF THE H7 LO TRACK. PERIODS OF SN HAVE BEEN MOST PERSISTENT IN THESE AREAS TDAY...WITH SN FALL RATES UP TO 0.5-0.75 INCH/HR. ALTHOUGH THE DRY SLOT HAS SWEPT THRU THE CNTRL COUNTIES...SOME -SN CONTINUES OVER MAINLY NCENTRAL MQT COUNTY WITH CYC UPSLOPE N WIND PROVIDING SUFFICIENT LIFT. ANOTHER AREA OF -SHRASN ASSOCIATED WITH THE DPVA/DEEP LYR QVECTOR CNVGC AHEAD OF THE UPR LO IS APRCHG THE SE COUNTIES...BUT PRESENCE OF LARGER SCALE DRY SLOT LOOKS TO BE LIMITING THE COVERAGE TO SCT -SHRASN. TO THE W...12Z YPL/INL RAOBS SHOW A DRIER/MORE STABLE AIRMASS IS PRESENT OVHD TO THE W OF THE DEFORMATION ZN IN MN...AND THERE IS LTL PCPN FALLING THERE. ALTHOUGH A FAIRLY IMPRESSIVE COMMA CLD APPEARS ASSOCIATED WITH THE SHRTWV DIGGING INTO THE NRN PLAINS...PCPN APPEARS TO BE CONFINED TO AN AREA NEAR LK WINNIPEG RIGHT UNDER THE COMMA HEAD. MAIN FCST CONCERNS TNGT ARE SN TRENDS/GOING HEADLINES. FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SHRTWV DIGGING INTO THE NRN PLAINS. TNGT...MODELS SHOW SFC LO LIFTING NEWD INTO SE ONTARIO TNGT...BUT CLOSED LO/DEEPER MSTR TENDING TO LINGER OVER THE UPR LKS DESPITE ARRIVAL OF DEEP LYR QVECTOR DVGC BY 06Z. AREA OF -SHRASN LIFTING NWD THRU LK MI AHEAD OF THE UPR LO WL IMPACT THE ERN ZNS THIS EVNG WITH AREAS OF FOG LINGERING THERE UNTIL SFC LO PASSES TO THE NE THIS EVNG AND COLDER AIR ARRIVES. SUSPECT LINGERING DEFORMATION ZN PCPN OVER THE WRN CWA WL SLOWLY DIMINISH WITH ARRIVAL OF THE NEGATIVE FORCING...SO ENDED THE GOING HEADLINES AS SCHEDULED 00Z TO 06Z FM SW TO NE. DOWNGRADED THE WARNINGS FOR BARAGA/MQT COUNTIES VALID THRU 0Z WITH BULK OF PCPN EXPECTED TO FALL FARTHER W ON CYC SIDE OF H7 LO TRACK. EVEN THOUGH THE STEADY SN WL TEND TO DIMINISH OVER THE W...CYC NW FLOW OF AIR/ARRIVAL OF COLDER AIR WITH H85 TEMPS PROGGED TO SINK AS LO AS -14C TO -15C BY 12Z TUE WL CAUSE NMRS SHSN TO PERSIST. BUT CONCERNED LO INVRN HGTS/DRY MID LVL AIR SHOWN ON THE 12Z INL/YPL RAOBS WL LIMIT THE COVERAGE/INTENSITY OF THE SHSN...SO WENT NO HIER THAN LIKELY POPS FOR NOW. TUE...DISTURBANCE MOVING THRU THE NRN PLAINS/ACCOMPANYING DEEP LYR QVECTOR CNVGC IS PROGGED TO MOVE TOWARD THE CWA...SO MAINTAINED GOING INCRSG POPS TO CATEGOCIAL NEAR LK SUP BY LATE AFTN WITH FAIRLY SHARP CYC NW FLOW ACTING AS AN ENHANCEMENT FACTOR IN THE PRESENCE OF DEEPER MSTR/H85 TEMPS NOT FAR FM -15C. SINCE FCST SDNGS SHOW THE DGZ SEVERAL THOUSAND FEET DEEP IN THE CONVECTIVE LYR...CONCERNED SOME ADVY INTENSITY LES MIGHT OCCUR LATER IN THE DAY...ESPECIALLY IN THE UPSLOPE AREAS OVER THE W. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 426 PM EDT MON MAR 11 2013 WITH AN UPPER LOW JUST E OF THE CWA AT 00Z WED AND A SFC TROUGH OVER LAKE SUPERIOR...850MB TEMPS WILL BE AROUND -14 WITH CYCLONIC NW-NNW LOW LEVEL WINDS. THESE CONDITIONS WILL BE FAVORABLE FOR LES TUE NIGHT...WITH WARMING TEMPS VERY DRY LOW LEVEL AIR MOVING IN WITH A SFC RIDGE LATE TUE NIGHT INTO WED NIGHT. EXPECT A RELATIVELY QUICK BURST OF MODERATE LES ALONG AND JUST BEHIND THE SFC TROUGH THAT MAY BRING A QUICK 2-4 INCHES OF SNOW OVER THE FAVORED HIGHER TERRAIN. WITH THE RATE THAT THE VERY DRY AIR MOVES IN LATE TUE NIGHT...LES WILL QUICKLY WEAKEN...AND SHOULD BE ALMOST COMPLETELY GONE BY 15Z WED /IF NOT A BIT EARLIER/. MODELS THEN INDICATE AN AREA OF INCREASED LOW LEVEL MOISTURE AND INCREASED LAKE INDUCED EQUILIBRIUM LEVELS MOVING ACROSS CENTRAL LAKE SUPERIOR ALONG A WEAK SFC TROUGH WED NIGHT. WILL KEEP SLIGHT CHANCE POPS E OF MARQUETTE AS CONDITIONS WILL STILL ONLY BE MARGINAL FOR LES. ELSEWHERE WED NIGHT...CLEARING OVER THE INTERIOR W SHOULD ALLOW MIN TEMPS TO FALL TO NEAR ZERO. A COUPLE OF SHORTWAVES LOOK TO MOVE NEARBY THU/THU NIGHT...BUT CONSENSUS OF MODELS PLACES BEST FORCING AND PRECIP N AND S OF THE CWA...SO WILL KEEP ANY POPS ON THE LOW SIDE. ANOTHER SHORTWAVE...BACKED UP BY THE LEFT EXIT REGION OF A 120+KT JET...MOVES THROUGH FRI INTO FRI NIGHT. MODEL VARY WITH TIMING...BUT GENERALLY AGREE ON OVERALL EXTENT/STRENGTH OF THE SYSTEM. MODELS PAINT A QUARTER TO A THIRD OF AN INCH OF QPF...AND THE BEST OMEGA LOOKS TO BE JUST BELOW AND INTO THE DGZ...WHICH SHOULD KEEP SNOW TO LIQUID RATIOS FROM GETTING TOO LOW. STILL DIFFICULT TO SAY GIVEN VOLATILE NATURE OF SHORTWAVES THAT FAR OUT...BUT COULD SEE A FEW INCHES OF SNOW ACROSS THE AREA. 850MB TEMPS AOB -14C AND N-NW FLOW BEHIND THE SYSTEM WOULD BRING SOME ADDITIONAL LES INTO SAT /AND POSSIBLY BEYOND BUT TOO UNCERTAIN IN ANY DETAILS THAT FAR OUT TO MENTION OR ADD TO THE FORECAST/. HIGHS TEMPS WILL BE IN THE 20S ON WED...WITH A WARM UP TO AROUND 30 ON THU AND INTO THE MID 30S ON FRI. TEMPS LOOK TO DECREASE GOING INTO THE WEEKEND AND EARLY NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 149 PM EDT MON MAR 11 2013 WINTER STORM STILL OVER NORTHERN UPR MICHIGAN...SO EXPECT POOR FLYING CONDITIONS TO CONTINUE. NNE WINDS TURN NNW TONIGHT. HEAVIER SNOW WITH MID-LEVEL LOW WILL CONTINUE AT IWD AND CMX INTO THIS EVENING. THEN...LK EFFECT SNOWS WITH IFR VSBY AND MVFR CIGS SHOULD CONTINUE THROUGH REST OF TAF PERIOD DUE TO LINGERING COOL AND MOIST FLOW THROUGH LOWEST 5KFT. AT SAW...CONDITIONS WILL IMPROVE STEADILY THROUGH LATE AFTN THROUGH TONIGHT AS HEAVIER SNOW REMAINS WEST THIS AFTN AND LK EFFECT DEVELOPING TONIGHT WILL NOT BE AS FAVORABLE WITH MORE OF A NW COMPONENT TO WIND. EVEN SO...PLENTY OF LINGERING MOISTURE AND CYCLONIC LOW-LEVEL WINDS SHOULD RESULT IN MVFR CONDITIONS INTO TUESDAY. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 426 PM EDT MON MAR 11 2013 EXPECT SLOWLY DIMINISHING NNE WINDS TO BACK TO THE NW TNGT INTO TUE AS SFC LO OVER ERN UPR MI THIS EVNG MOVES NEWD THRU ONTARIO TOWARD JAMES BAY. EVEN THOUGH WINDS WL BE SLOWLY DIMINISHING...THE ARRIVAL OF COLDER AIR WL RESULT IN SOME FREEZING SPRAY. A TROUGH WILL MOVE THROUGH LATE TUESDAY AND TUESDAY NIGHT...CAUSING WINDS TO GUST NEAR 35KTS OVER CENTRAL AND EASTERN LAKE SUPERIOR. WINDS RELAX WEDNESDAY AND WEDNESDAY NIGHT AS A RIDGE MOVES THROUGH. BEHIND THE RIDGE. WINDS WILL REMAIN BELOW 20KTS THROUGH THE REST OF THE WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 11 PM EDT THIS EVENING FOR MIZ004- 005. WINTER STORM WARNING UNTIL 11 PM EDT THIS EVENING FOR MIZ002-084. WINTER STORM WARNING UNTIL 2 AM EDT TUESDAY FOR MIZ003. WINTER WEATHER ADVISORY UNTIL 2 AM EDT TUESDAY FOR MIZ001. WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MIZ009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...TITUS AVIATION...JLA MARINE...KC/TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1100 AM EDT MON MAR 11 2013 .UPDATE... ISSUED AT 1059 AM EDT MON MAR 11 2013 12Z RAOBS/LATEST STLT IMAGERY AND RUC ANALYSIS SHOW CLOSED UPR LO OVER SW WI LIFTING NEWD AS DISTURBANCE DIGS INTO THE NRN PLAINS. DRY SLOT IN ADVANCE OF THIS DISTURBANCE HAS OVERSRPEAD MUCH OF THE SCNTRL AND ERN CWA...LIMITING THE PCPN IN THESE AREAS TO SCT -SHSN OR EVEN -SHRA OVER THE E WHERE SFC TEMPS ARE NOW ABV 32. BUT WET SN STRETCHING FM SE MN THRU WCENTRAL WI INTO THE W HALF OF UPR MI ON CYC SIDE OF H7 LO TRACK. A FEW CHGS TO HEADLINES FOR NOW...PLAN TO CANX GOING WRNG FOR ALGER COUNTY AS DRY SLOT HAS LIFTED THRU THIS AREA. ALTHOUGH THERE COULD BE SOME SN OVER THE FAR W PORTION OF THE COUNTY...BULK OF THIS AREA WL SEE ONLY SCT -SHSN THRU THE DAY. MQT COUNTY WL BE ON THE ACYC SIDE OF THE H7 LO TRACK AS WELL...BUT PERSISTENT NE SFC WIND IS FVRBL FOR LINGERING WET SN OVER THE HIER TERRAIN. WL CONT GOING HEADLINES FOR THE WRN ZNS...WHICH WL BE MOST IMPACTED BY SN UNDER THE DEFORMATION ZN. SINCE TEMPS ARE ABV 32 WHERE RA IS FALLING OVER THE E FM NEWBERRY TO MANISTIQUE...TOOK OUT MENTION OF FZRA. ALSO ADDED MENTION OF PATCHY FOG WITH LLVL MSTR UNDER THE DRY SLOT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 509 AM EDT MON MAR 11 2013 UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER SOUTHERN IOWA WITH AN ASSOCIATED TROUGH OVER THE CENTRAL PLAINS. THIS CLOSED LOW WILL CONTINUE TO HEAD NORTHEAST TODAY AND OPEN UP. THIS TROUGH WILL THEN TAKE ON A NEGATIVE TILT OVER THE UPPER GREAT LAKES. THIS TROUGH MOVES OUT TONIGHT. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE OVER THE AREA WITH DEEP MOISTURE TODAY BEFORE THE STRONG Q-VECTOR CONVERGENCE MOVES OUT BY TONIGHT. NAM HAS SOME ISENTROPIC LIFT ON I280OK-I295K WITH MOISTURE THIS MORNING THAT MOVES OUT BY THIS EVENING. BUSY MORNING DEALING WITH ALL SORTS OF WEATHER AND MIXED PCPN. HEAVY SNOW CONTINUES ACROSS THE CENTRAL AND WESTERN CWA WITH SOME RAIN MIXED IN WITH SOME FREEZING RAIN OVER THE SOUTH AND EAST. LEAD SHORTWAVE ON WATER VAPOR IS MOVING THROUGH AND THERE IS A BREAK IN PCPN THAT IS DEVELOPING ACROSS NE WI AND THE FAR SOUTHERN U.P. ASSOCIATED WITH A DRY SLOT. THIS DRY SLOT IS HEADING NORTH AND COULD END UP ENDING THE PCPN SOONER THAN EXPECTED EXCEPT IN UPSLOPE AREAS. AM A LITTLE CONCERNED THAT THE DRY SLOT WOULD HAVE SOME FREEZING DRIZZLE ASSOCIATED WITH IT. FOR THIS REASON...KEPT UP ALL HEADLINES FOR NOW AND WILL PROBABLY HAVE TO CANCEL SOME OF THEM EARLIER IF IT APPARENT THAT THE HEAVIEST PCPN IS DONE ALREADY. OTHERWISE...KEPT IN FREEZING RAIN AND RAIN THIS MORNING ACROSS THE SOUTH AND EAST WITH SNOW IN THE WEST AND QUICKLY LOOKED AT A FEW SOUNDINGS FOR ISQ...ESC AND ERY OFF OF BUFKIT AND CONFIRMED PREVIOUS THINKING OF MIXED PCPN THIS MORNING. OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE PREVIOUS FORECAST EXCEPT PUSH TIMING UP FOR HEAVIER PCPN MOVING OUT THIS MORNING. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 509 AM EDT MON MAR 11 2013 LOW PRESSURE SYSTEM THAT WILL BE AFFECTING THE AREA TODAY AND TONIGHT WILL BE EXITING THROUGH NORTHWEST QUEBEC ON TUESDAY...BUT WILL LINGER A SURFACE TROUGH BACK TO THE SOUTHEAST ACROSS UPPER MICHIGAN. THIS...COMBINED WITH THE UPPER TROUGH OVER THE AREA WILL LEAD TO LAKE EFFECT/ENHANCED SNOW SHOWERS OVER THE AREA ON TUESDAY INTO TUESDAY NIGHT. 850MB TEMPS AROUND -13C TO -16C WILL PROVIDE ENOUGH OVER LAKE INSTABILITY AND WHEN COMBINED WITH THE DEEPER MOISTURE LINGERING UNDER THE UPPER TROUGH OVER THE GREAT LAKES REGION WILL LEAD TO THE HEAVIEST SNOW IN THE NORTH-NORTHWEST WIND SNOW BELTS. LATEST TRENDS IN THE MODELS ARE INDICATING THE DRIER AIR ALOFT TO BE A LITTLE FARTHER WEST FOR TUESDAY AND THINK THERE WILL BE A BETTER CHANCE FOR SNOW OVER THE WESTERN PORTIONS OF THE CWA THAN PREVIOUS THOUGHT. WITH THE GREATER CONFIDENCE ON THE SNOW ON TUESDAY...HAVE BUMPED POPS NEAR LAKE SUPERIOR TO DEFINITE VALUES WITH THE HIGHEST POPS OVER THE KEWEENAW AND NORTH CENTRAL UPPER MICHIGAN. FARTHER INLAND...WOULD EXPECT SCATTERED SNOW SHOWERS WITH THE ABUNDANT MOISTURE AND CONTINUING UPWARD MOTION UNDER THE UPPER TROUGH...ESPECIALLY ON TUESDAY AFTERNOON. SNOWFALL AMOUNTS DURING THE DAY ON TUESDAY WILL BE IN THE 1-4 INCH RANGE ACROSS MUCH OF THE AREA...WITH THE HIGHEST AMOUNTS OVER THE FAVORED LOCATIONS NEAR LAKE SUPERIOR. IN ADDITION...INCREASING WINDS AND A TREND TOWARDS MORE FLUFFY SNOW SHOULD LEAD TO BLOWING SNOW FOR AREAS NEAR LAKE SUPERIOR TUESDAY AFTERNOON INTO TUESDAY TONIGHT. THESE TWO FACTORS MAY BE ENOUGH FOR A FUTURE ADVISORY FOR THE COUNTIES NEAR LAKE SUPERIOR AND WILL MENTION THE LIGHT/MODERATE SNOW IN THE HWO. WITH THE UPPER TROUGH STARTING TO SHIFT TO THE EAST ON TUESDAY NIGHT AND INTO WEDNESDAY...DRIER AIR WILL START TO WORK INTO THE UPPER GREAT LAKES AREA AND DECREASE THE INTENSITY OF THE SNOW SHOWERS. COMPARED TO 24HRS AGO...THE MODELS HAVE SHOWN A MUCH QUICKER DRYING TREND AND HAVE FOLLOWED SUIT WITH POPS. LATEST IDEA FROM THE NAM/GFS IS FOR THE LAKE EFFECT SNOW TO BE DONE BY WEDNESDAY AFTERNOON. THERE MAY BE A FEW SNOW SHOWERS REDEVELOPING OVER THE EAST LATE IN THE AFTERNOON OR EARLY EVENING AS THERE ARE HINTS OF A SECOND AREA OF 925-850MB MOISTURE MOVING THROUGH WITH FAVORABLE 850MB TEMPS OF -13C. THE UPPER RIDGE WILL PUSH IN ON WEDNESDAY NIGHT AND ALLOW A SURFACE HIGH TO MOVE INTO THE AREA. ANY ISOLATED SNOW SHOWERS ON WEDNESDAY EVENING SHOULD QUICKLY COME TO AN END AS THE SMALL POCKET OF MOISTURE DEPARTS. WITH THE DRY AIR AND WEAKENING WINDS WITH THE APPROACHING HIGH...HAVE TRENDED TEMPS COLDER ON WEDNESDAY NIGHT. CURRENT FORECAST HAS INTERIOR WEST TEMPS IN THE LOW SINGLE DIGITS AND THERE IS THE POTENTIAL FOR SOME LOCATIONS TO FALL BELOW BELOW ZERO. WITH AN UPPER RIDGE OVER THE WESTERN CONUS...AREA WILL BE UNDER NORTHWEST FLOW ALOFT FROM THURSDAY THROUGH THE WEEKEND. THIS LEADS TO THE POTENTIAL FOR SHORTWAVES AND WEAK LOW PRESSURE SYSTEMS TO QUICKLY SLIDE ACROSS THE AREA. THERE ARE STILL HINTS OF A SHORTWAVE FOR THE THURSDAY INTO THURSDAY NIGHT...BUT LATEST TRENDS HAVE THAT SLIDING TO THE SOUTHWEST OF THE CWA. BASED OFF THE 00Z RUNS...THE BEST POTENTIAL FOR A SHORTWAVE TO AFFECT THE AREA WILL BE ON SATURDAY AND WILL TREND TOWARDS CHANCE POPS FOR THAT PERIOD. HIGHS TUESDAY AND WEDNESDAY WILL BE SIMILAR TO VALUES YOU WOULD EXPECT TO SEE A MONTH AGO /MID 20S/. THERE WILL BE A SLIGHT WARM UP FOR THE SECOND HALF OF THE WEEK AND INTO THE WEEKEND...BUT HIGHS SHOULD STILL STAY AT OR SLIGHTLY BELOW NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 714 AM EDT MON MAR 11 2013 WINTER STORM TRACKING INTO THE UPPER GREAT LAKES WILL CONTINUE TO BE THE DOMINANT FEATURE FOR MOST OF THIS FCST PERIOD. ON THE WESTERN FRINGE OF THE STORM SYSTEM...IFR CONDITIONS SHOULD PREVAIL AT KIWD THRU THE MORNING HRS BEFORE CONDITIONS IMPROVE TO MVFR THROUGH THE REST OF THE PERIOD THERE. HEAVIER SNOW WILL IMPACT KCMX AND ESPECIALLY KSAW...LIKELY RESULTING IN IFR CONDITIONS THRU MUCH OF THE MORNING HRS. N/NE WINDS GUSTING 20-30KT...STRONGEST AT KSAW GIVEN FAVORABLE WIND DIRECTION...WILL PRODUCE BLSN AS WELL. THIS AFTN...EXPECT SOME IMPROVEMENT TO MVFR AT KCMX/KSAW WHERE THINGS WILL STAY THROUGH TONIGHT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 509 AM EDT MON MAR 11 2013 DECIDED TO GO WITH A GALE WARNING FOR EASTERN LAKE SUPERIOR THIS MORNING AS THE SFC PRESSURE GRADIENT TIGHTENS AS A LOW MOVES THROUGH NORTHERN LAKE MICHIGAN INTO NORTHERN LAKE HURON TODAY. FREQUENT GUSTS UP TO 35 KNOTS WILL BE EXPECTED THIS MORNING. WINDS CRANK UP AGAIN TO CLOSE TO GALES ACROSS EASTERN LAKE SUPERIOR TUE NIGHT. AFTER THAT...HIGH PRESSURE BUILDS IN AND THE WINDS WILL DIMINISH THROUGH THE REST OF THE FORECAST PERIOD. THERE WILL BE SOME FREEZING SPRAY OUT ON LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WARNING UNTIL 11 PM EDT THIS EVENING FOR MIZ004-005- 084. WINTER WEATHER ADVISORY UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR MIZ002-009. WINTER WEATHER ADVISORY UNTIL 2 AM EDT TUESDAY FOR MIZ001-003. LAKE SUPERIOR... GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LSZ266-267. LAKE MICHIGAN... NONE. && $$ UPDATE...KC SHORT TERM...07 LONG TERM...SRF AVIATION...07 MARINE...07
AREA FORECAST DISCUSSION
NWS DULUTH MN
317 PM CDT MON MAR 11 2013 .SHORT TERM...CWA REMAINS UNDER THE INFLUENCE OF A CYCLONIC CIRCULATION TO THE EAST OF THE REGION. ORGANIZED FORCING IN THE FORM OF WEAK FRONTOGENESIS HAS KEPT MORE PERSISTENT SNOW OVER ERN EDGE OF REGION. ELSEWHERE...ABUNDANT CLOUD COVER AND A FEW FLURRIES ARE OCCURRING. TONIGHT...AN AMPLIFYING MID LVL SYSTEM WILL TRACK FROM SRN MANITOBA TO JUST SOUTH OF THE BRD LAKES VICINITY. IT IS DIFFICULT TO FIND MUCH IN THE WAY OF A SFC REFLECTION ASSOCIATED WITH THIS FEATURE EITHER IN THE PRESSURE OR WIND FIELDS. USED A BLEND OF THE SREF AND EC TO KEEP POPS FOCUSED IN TWO AREAS. FIRST...ACROSS THE SRN TIER OF ZONES CLOSER TO TRACK OF UPPER FEATURE. SECOND...AS COLDER AIR MOVES ACROSS LAKE SUPERIOR...SOME INCREASE IN LES MAY OCCUR OVER ERN WISC SNOWBELTS. TOMORROW...UPPER LOW SCOOTS QUICKLY SE OF REGION BY MIDDAY WITH DEEPENING OF NRLY FLOW ACROSS CWA. MOST PROBABLE AREAS FOR PRECIP WILL BE OVER ARROWHEAD AND WISC SNOWBELTS. A WRAPAROUND LOBE OF DEEP LAYER MOISTURE ASSOCIATED WITH A MIGRATORY SHORTWAVE TROF WILL ROTATE WESTWARD INTO ARROWHEAD DURING THE DAY. THIS IS REFLECTED IN THE EC AND THE SPC WRF/NMM. 85H THERMAL TROUGH SETTLES SOUTHWARD ACROSS LAKE SUPERIOR IN THE AFTERNOON. NEARLY UNIDIRECTIONAL FLOW IN SFC/85H LAYER COMBINED WITH INCREASINGLY FAVORABLE SYNOPTIC SCALE MOISTURE WILL PROMOTE ADDITIONAL SNOW INTO SNOWBELTS. MAY NEED TO CONSIDER AN ADVISORY FOR LATE AFTERNOON INTO EVENING. TUESDAY NIGHT THROUGH MONDAY. THE NORTHLAND WILL CONTINUE TO BE INFLUENCED BY A TROUGH TUESDAY NIGHT...WITH SOME LIGHT SNOW OR FLURRIES WILL LINGERING TUESDAY EVENING...BUT DIMINISHING OVERNIGHT. LITTLE ACCUMULATION IS EXPECTED FOR MOST AREAS. THE EXCEPTION WILL BE ALONG THE SOUTH SHORE...MAINLY THE SNOWBELT REGION OF ASHLAND/IRON COUNTIES. CHANCES FOR LAKE EFFECT SNOW SHOWERS LOOK PRETTY GOOD WITH NORTHERLY WINDS AND 850MB TEMPERATURES DROPPING TO AROUND -14C TO -16C. WE INCREASED POPS AND SNOW AMOUNTS ACROSS ASHLAND/IRON COUNTIES TUESDAY NIGHT...WITH THE BEST CHANCE FROM 00Z WED TO ABOUT 09Z WED. INVERSION LEVELS DROP LATE AND DRIER AIR MOVES OVER THE LAKE LATE TUESDAY NIGHT AND THROUGH WEDNESDAY. WINDS WILL ALSO BACK WEDNESDAY. AN ADVISORY MAY BE NEEDED FOR IRON AND ASHLAND COUNTIES. A WEST NORTHWEST FLOW WILL PREVAIL THROUGH MOST OF THE REST OF PERIOD WITH SEVERAL SHORTWAVES MOVING THROUGH AND BRINGING PERIODIC CHANCES FOR PRECIPITATION. MOST OF THE SHORTWAVES WILL ONLY BRING LIGHT PRECIPITATION. WE HAVE A CHANCE FOR LIGHT SNOW WEDNESDAY NIGHT INTO THURSDAY AS WAA MOVES THROUGH THE AREA. THE PRECIP LOOKS RATHER LIGHT...AND PRECIP TYPE COULD BE IN QUESTION. 850MB TEMPS ARE FORECAST TO RISE TO AROUND +4C OVER OUR SOUTHWEST ZONES BY 00Z FRI...AND REMAIN AROUND -4C FAR NORTHEAST. FORECAST SOUNDINGS ALSO SHOW THE MOIST LAYER IS RATHER LIMITED...WITH ICE CRYSTAL PRESENCE IN QUESTION. LATER SHIFTS MAY HAVE TO ADD SOME MIXED PRECIP ONCE WE GET CLOSER. A MORE SIGNIFICANT CLIPPER SYSTEM IS FORECAST BY THE ECMWF TO AFFECT THE NORTHLAND FRIDAY INTO FRIDAY NIGHT...WITH THE GFS ABOUT 12 HOURS FASTER. A MIX COULD BE POSSIBLE ONCE AGAIN...ESPECIALLY OVER THE SOUTHERN HALF. A FEW INCHES OF SNOW WILL BE POSSIBLE WITH THIS SYSTEM. THE GFS SHOWS THE CORE OF THE PRECIPITATION FURTHER NORTH THAN THE ECMWF. BOTH THE GFS AND ECMWF DO SHOW COLDER AIR MOVING IN BEHIND THIS CLIPPER...LASTING INTO THE WEEKEND. HIGH TEMPERATURES WILL RANGE FROM THE UPPER TWENTIES TO LOWER THIRTIES WEDNESDAY. THEY WILL WARM INTO THE LOWER TO MID THIRTIES THURSDAY/FRIDAY...AND COOL A BIT BEHIND THE CLIPPER OVER THE WEEKEND. .AVIATION...18Z TAFS MIX OF MVFR AND LOW VFR CONDITIONS COVERED THE NORTHLAND EARLY THIS AFTERNOON...WITH SOME LIGHT SNOW OR FLURRIES IN SPOTS. OVERALL...WE EXPECT THESE CONDITIONS TO CONTINUE THROUGH THE PERIOD. THE RUC 900-925MB PRESSURE DEFICITS WERE INDICATING SOME DECREASE IN CLOUD COVER THIS EVENING...BUT JUST DON`T HAVE THE CONFIDENCE TO DIMINISH CEILINGS TOO MUCH. A CLIPPER MAY SPREAD ADDITIONAL CLOUDS AND PERHAPS SOME ADDITIONAL LIGHT SNOW TO THE REGION TONIGHT. .POINT TEMPS/POPS... DLH 15 29 11 30 / 20 30 10 0 INL 11 27 6 29 / 20 20 10 0 BRD 16 29 10 30 / 30 30 10 10 HYR 16 30 12 32 / 30 60 20 10 ASX 16 29 15 30 / 30 60 30 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...CANNON LONG TERM....MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
123 PM CDT MON MAR 11 2013 .AVIATION...18Z TAFS MIX OF MVFR AND LOW VFR CONDITIONS COVERED THE NORTHLAND EARLY THIS AFTERNOON...WITH SOME LIGHT SNOW OR FLURRIES IN SPOTS. OVERALL...WE EXPECT THESE CONDITIONS TO CONTINUE THROUGH THE PERIOD. THE RUC 900-925MB PRESSURE DEFICITS WERE INDICATING SOME DECREASE IN CLOUD COVER THIS EVENING...BUT JUST DON`T HAVE THE CONFIDENCE TO DIMINISH CEILINGS TOO MUCH. A CLIPPER MAY SPREAD ADDITIONAL CLOUDS AND PERHAPS SOME ADDITIONAL LIGHT SNOW TO THE REGION TONIGHT. && .PREV DISCUSSION... /ISSUED 1009 AM CDT MON MAR 11 2013/ UPDATE...INCREASED SKY COVERAGE ACROSS MOST OF THE ERN CWA WITH SLOWER CLEARING TREND INDICATED BY SAT IMAGERY. AREA OF CLEARING OVER WRN CWA MAY BE SHORT LIVED AS MID LVL MOISTURE FROM NEXT SYSTEM IS APPROACHING WRN BORDER ALREADY. FLURRIES WILL REMAIN NEAR TWIN PORTS UNTIL MIDDAY WHEN RELAXING OF CIRCULATION FROM ERN SYSTEM BEGINS. BDRY LYR FLOW BACKS MORE NRLY THIS AFTERNOON OVER WISCONSIN. INCREASED POPS OVER ERN WISC ZONES REMAINDER OF MORNING AS LATEST SPC MESOANALYSIS...AND 88D RETURNS...SHOWS A DEFORMATION AXIS STRETCHING ACROSS PRICE COUNTY. WILL INCREASE SNOW ACCUMULATIONS TO 1 TO 3 INCHES. PREV DISCUSSION... /ISSUED 307 AM CDT MON MAR 11 2013/ SHORT TERM...TODAY AND TONIGHT. THE MAIN FOCUS FOR THE SHORT TERM IS THE SNOW IN EASTERN AREAS OF THE NW WI FORECAST AREA. CURRENT SURFACE AND RADAR ANALYSIS INDICATE MODERATE SNOW FALLING ACROSS AREAS EAST OF A LINE FROM IRONWOOD THROUGH GLIDDEN. VSBYS HAVE RANGED FROM 1/2 TO 1 MILE AT PBH AND IRONWOOD THE PAST TWO HOURS. NAM HAD HAD MORE SNOWFALL WITH SYSTEM THAN THE GFS/ECMWF BUT THE SREF HAS BEEN CLOSER THE PAST COUPLE OF RUNS WITH PLACEMENT. AS INDICATED BY PREVIOUS SHIFT...THE NAM CROSS SECTIONS SHOW GOOD SATURATION/UPWARD MOTION IN THE DENDRITIC EARLY THIS MORNING THROUGH 12Z. IT WILL BE CLOSE...BUT SOME AREA IN SOUTHERN PRICE COUNTY COULD SEE 6 INCHES. THE OTHER COUNTIES IN THE ADVISORY HAVE SOME SNOW BANDS OVER THEM SO THE 3-5 INCHES LOOK GOOD. WILL KEEP CURRENT HEADLINES UP THROUGH 17Z AS PLANNED. THE SNOW WILL TAPER OFF TO LIGHT SNOW BY EARLY THIS AFTERNOON AS THE LOW MOVES OFF TO THE NORTHEAST. WILL ALSO HAVE FLURRIES IN THE REST OF FCST AREA THIS MORNING AS SFC OBS HAVE BEEN REPORTING THEM. EXTENDED...TUESDAY THROUGH MONDAY. IT IS LOOKING A BIT DRIER FOR TUESDAY NOW THAN IT HAS OVER THE PAST SEVERAL RUNS. THE MODELS GENERALLY AGREE ON FAIRLY DRY AIR ENTRAINMENT INTO THE CWA BEHIND DEPARTING LOW PRESSURE. THE BEST CHANCE OF LIGHT SNOW WOULD BE ALONG THE SOUTH SHORE OF LAKE SUPERIOR. ANOTHER STRONGER SHORTWAVE SHOULD MOVE GENERALLY SOUTH OF THE CWA TUESDAY AND TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN ON WEDNESDAY BRINGING A BIT OF SUNSHINE TO THE NORTHLAND. ANOTHER SHOT OF LIGHT SNOW IS POSSIBLE ON THURSDAY BUT ONLY LOW POPS WARRANTED FOR RELATIVELY WEAK WAA EVENT. A BETTER SNOWFALL EVENT IS EXPECTED TO ARRIVE ON FRIDAY AND LINGER INTO SATURDAY AND EVEN A BIT INTO SATURDAY NIGHT. HAVE RAISED POPS INTO THE HIGH CHANCE CATEGORY BUT WILL LIKELY NEED TO CONTINUE TO TREND TOWARD A LIKELY TYPE WORDING. COOL HIGH PRESSURE WILL THEN BUILD IN FOR THE REMAINDER OF THE WEEKEND WITH SOME SCATTERED LIGHT SNOW SHOWERS BY MONDAY. OVERALL WE ARE LOOKING AT TEMPERATURES IN THE 30S FOR THE MOST PART...WITH SOME 40S LATE IN THE WEEK AND INTO THE UPCOMING WEEKEND. SHOULD BE A GOOD RUN OF DAYTIME MELTING AND NIGHTTIME COOLING WHICH WOULD BE GOOD FOR SPRING SNOWMELT ISSUES. && .POINT TEMPS/POPS... DLH 15 29 12 31 / 20 20 10 0 INL 11 27 8 30 / 20 20 10 0 BRD 16 29 11 30 / 30 30 10 10 HYR 16 30 13 33 / 30 30 20 10 ASX 16 29 16 31 / 30 40 30 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
331 AM CDT MON MAR 11 2013 .DISCUSSION... WILL SEE A GOOD COOLDOWN FOR THE START OF THE WEEK BEHIND SHORTWAVE CURRENTLY DROPPING SOUTHEAST THROUGH SASKATCHEWAN. THAT FEATURE HELPS CARVE OUT A NICE TROUGH FROM OUR AREA THROUGH THE GREAT LAKES REGION BY TUESDAY... WITH CYCLONIC FLOW AND BELOW NORMAL TEMPERATURES LIKELY BRINGING SOME SNOW SHOWER ACTIVITY GIVEN THE EASE WITH WHICH WE CAN GENERATE STEEP LOW LEVEL LAPSE RATES NOW. AFTER THAT... THE LARGE SCALE PATTERN LOOKS TO MODERATE OVER THE SECOND HALF OF THE WEEK... WITH NORTHWEST FLOW GIVING WAY TO MORE IN THE WAY OF RIDGING AND WESTERLY DOWNSLOPING FLOW FROM THE ROCKIES. THAT COULD BRING SOME CHANCES FOR MIXED PCPN DURING THE END OF THE WEEK INTO THE WEEKEND... ALTHOUGH THERE CERTAINLY DON/T APPEAR TO BE ANY SIGNIFICANT SYSTEMS ON THE HORIZON. FOR SIGNIFICANCE... ATTENTION IS STILL SOMEWHAT FIXED ON THE SHORT TERM... ALTHOUGH THAT IS BECOMING LESS INTERESTING AS WELL. RADAR TRENDS OVER THE PAST FEW HOURS HAVE DIMINISHED MARKEDLY AS UPPER RIDGING ENCROACHES FROM THE WEST AND THE UPPER WAVE TO OUR SOUTH HAS SHEARED OUT AND OPENED UP A BIT. THE HIGH RESOLUTION GUIDANCE... INCLUDING THE HRRR... LOCAL WRF-ARW... AND THE HOPWRF... ALL DID A NICE JOB OF SHOWING THE RAPID WEAKENING TREND... AND GENERALLY AGREE THAT ANY SIGNIFICANT PCPN IS DONE FOR THE AREA. HOWEVER... A NARROW BAND WILL LIKELY HANG ON INTO THE MORNING HOURS FROM FAR SOUTHEAST MINNESOTA THROUGH OUR FAR EASTERN COUNTIES. THE AFOREMENTIONED HIGH RESOLUTION SOLUTIONS ALSO SUGGEST A SLIGHT REJUVENATION OF ACTIVITY IN THAT AREA IN THE 12-15Z TIME FRAME... SO LOCATIONS FROM NEAR EAU CLAIRE SOUTH AND EASTWARD COULD STILL SEE SOME ADDITIONAL LIGHT ACCUMULATIONS. THAT BEING SAID... PLAN TO DROP MOST OF THE HEADLINES BY 09Z... LEAVING ONLY THINGS OVER THE FAR EAST. COULD SEE SOME FLURRIES OR SNOW SHOWERS LINGER OVER PORTIONS OF THE AREA TONIGHT... MAINLY THE NORTH HALF... WHERE CYCLONIC FLOW WILL LINGER AND THE SECONDARY SHORTWAVE AND TROUGH WILL ARRIVE LATE TONIGHT. THAT FEATURE WILL HELP KEEP CYCLONIC BOUNDARY LAYER FLOW IN PLACE THROUGH THE DAY ON TUESDAY AND GIVEN THE SHARPLY COOLER TEMPERATURES ALOFT THAT IT BRINGS INTO THE AREA... THINK WE SHOULD SEE A FAIR AMOUNT OF SCATTERED SNOW SHOWER ACTIVITY DURING THE DAY ON TUESDAY. THINGS THEN LOOK TO BE FAIRLY QUIET THROUGH WEDNESDAY... WITH THE NEXT CHANCE OF PCPN HOLDING OFF UNTIL THURSDAY WHEN WE SEE RETURN FLOW AND DECENT WARM ADVECTION SETUP ACROSS THE REGION. AT THIS POINT IT LOOKS LIKE THE EASTERN AND NORTHERN FORECAST AREA HAVE THE BEST SHOT AT SEEING ANY OF THIS WARM ADVECTION PCPN GIVEN WHERE THINGS APPEAR TO SATURATE ALONG THE ISENTROPIC SURFACES. ANY PCPN ON THURSDAY SHOULD STILL BE IN THE FORM OF SNOW. A BETTER SHOT AT SEEING SOME PCPN ACROSS THE AREA WILL COME FROM FRIDAY INTO THE WEEKEND AS THE BAROCLINIC ZONE SETS UP ACROSS THE AREA AND A FEW SHORTWAVES RIPPLE EAST-SOUTHEAST ALONG IT. THE MAIN IMPULSE LOOKS TO SWING ACROSS THE AREA LATE FRIDAY INTO EARLY SATURDAY... BUT THAT IS AROUND THE TIME WHEN THE ECMWF AND GFS START TO EXHIBIT SIGNIFICANT DIFFERENCES IN THE LARGE SCALE FLOW ACROSS THE CONTINENT... SO THERE IS CERTAINLY A FAIR AMOUNT OF UNCERTAINTY AT THIS POINT. INCLUDED SOME POPS FOR MUCH OF THE TIME FROM FRIDAY THROUGH SUNDAY... ALTHOUGH WITH THE POSSIBILITY OF MIXED PCPN GIVEN THE FORECAST SOUNDINGS AND GENERAL WARM ADVECTION PATTERN. && .AVIATION.../06Z TAF ISSUANCE/ /ISSUED 1158 PM CDT SUN MAR 10 2013/ HEAVY SNOW WELL UNDER WAY FROM SOUTH CENTRAL MN UP INTO WRN WI. HOWEVER...ONLY EAU WILL HAVE TO DEAL WITH THE BRUNT OF THE SNOW... WITH SNOW BAND MAKING IT NO FURTHER THAN ABOUT 5-10 MILES FROM MSP. BASED ON RAP/NAM HOURLY SNOWFALL FORECASTS...HEAVIEST SNOW HAPPENING NOW...WITH 1/2SM TYPE SNOW NOT LASTING MUCH PAST 7Z. WILL HAVE TO WATCH FOR A SECOND BAND OF HEAVIER SNOW FROM ABOUT 12Z TO 15Z AS MAIN UPPER LOW MOVES INTO CENTRAL WI. THE HRRR HAS BEEN BACK AND FORTH WITH WHERE THIS BAND SETS UP BETWEEN EAU AND BCK...SO JUST LEFT GENERAL MVFR VIS -SN DURING THE MORNING...BUT DEPENDING ON WHERE THIS SECOND BAND SETS UP...THERE COULD BE ANOTHER BOUT OF IFR OR LOWER VIS THERE. EVERYWHERE ELSE IT IS A CIG PROBLEM. AXN HAS FOUND ITSELF JUST WEST OF THE LOW CLOUDS AND IT SHOULD STAY THERE THROUGH MONDAY AFTERNOON. FOR OTHER TERMINALS...HEIGHTS SHOULD BE FAIRLY CONSTANT THROUGH THE NIGHT. SHOULD SEE SOME BREAKS BY MORNING...WITH CATEGORICAL IMPROVEMENTS IN CIGS ACROSS MN BY THE AFTERNOON...BUT THERE IS THE POSSIBILITY THAT ERN MN REMAINS IN MVFR CIGS THROUGH THE DURATION OF THE TAF PERIOD. TOWARD THE END OF THE TAF PERIOD...STRONG WAVE CURRENTLY UP IN ALBERTA WILL DIVE SE INTO MN ON NW FLOW. THIS WILL BRING MVFR CIGS BACK TO WRN MN AFTER 00Z AND THEY WILL BE CLOSE TO AXN/RWF BY THE END OF THIS TAF PERIOD. KMSP...CONFIDENCE IS HIGH THAT FIELD REMAINS IN THE FRONT ROW SEATS WITH ONGOING SNOW STORM JUST TO THE SE. FLIGHTS ON APPROACH FOR THE 12S WILL LIKELY BE COMING THROUGH SNOW ON THEIR WAY IN...BUT NOT EXPECTING ANYTHING WORSE THAN A FEW FLURRIES FOR THE FIELD. CIGS WILL BE FLIRTING WITH 017 THROUGH THE REST OF TONIGHT...BUT THEY SHOULD REMAIN ABOVE THIS LEVEL. CONFIDENCE IS LOW IN CLEARING TOMORROW AFTERNOON...WITH IT VERY PLAUSIBLE THAT MVFR CIGS NEVER BECOME BETTER THAN BKN BEFORE CLOUDS FROM NW SYSTEM SHOW UP. FOR WINDS...SPEEDS WILL BE FAIRLY CONSISTENT IN THE 10-15 KT RANGE WITH A SLOW BACKING TOWARD THE WEST THIS PERIOD. /OUTLOOK FOR KMSP/ TUE...MVFR CIGS/VSBYS POSSIBLE WITH -SN. NW WIND 15G25KTS. WED...VFR. NW WIND 5 TO 10 KTS BACKING TO SW. THU...VFR. S WIND AROUND 5 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL 4 AM CDT EARLY THIS MORNING FOR FARIBAULT-FREEBORN-GOODHUE-STEELE-WASECA. WINTER WEATHER ADVISORY UNTIL 4 AM CDT EARLY THIS MORNING FOR BLUE EARTH-MARTIN-RICE. WI...WINTER STORM WARNING UNTIL 4 AM CDT EARLY THIS MORNING FOR DUNN- PIERCE. WINTER STORM WARNING UNTIL 10 AM CDT THIS MORNING FOR CHIPPEWA- EAU CLAIRE-PEPIN. WINTER WEATHER ADVISORY UNTIL 10 AM CDT THIS MORNING FOR RUSK. && $$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1158 PM CDT SUN MAR 10 2013 .UPDATE... 06Z AVIATION DISCUSSION ADDED BELOW. && .PREV DISCUSSION... /ISSUED 854 PM CDT SUN MAR 10 2013/ WINTER STORM BEGINNING TO TAKE SHAPE THIS EVENING AS SFC LOW MOVES INTO THE QUAD CITIES. LAST FEW RUNS OF THE RAP HAVE BEEN REALLY UNLOADING WITH HEAVY SNOW FROM CENTRAL FARIBAULT COUNTY...UP TO OWATONNA...LAKE CITY...AND EAU CLAIRE/CHIP FALLS. WITH THE RAP AND HRRR COMING IN A BIT FARTHER NW WITH THE HEAVIER SNOW...TACKED ON A FEW MORE COUNTIES TO THE WARNING...WITH SLIGHTLY HIGHER AMOUNTS EXPECTED AS WELL IN THE ALBERT LEA AND EAU CLAIRE AREAS. CURRENT RADAR SHOWING A RATHER STRONG BAND SETTING UP FROM NEAR THE CITY OF BLUE EARTH UP TOWARD LAKE CITY. AT TIMES HAVE SEEN KAEL AND KTOB GO DOWN TO A HALF MILE VIS WITH THIS BAND OVERHEAD...AND A CALL TO FARIBAULT COUNTY REVEALED 2 INCHES ALREADY IN THE CITY OF BLUE EARTH. BASED ON THE RAP/SPC MESO ANALYSIS...THIS LOOKS TO BE THE RESULT OF A COMBO OF FGEN AROUND THE H85 LAYER...ALONG WITH STRONG MOISTURE TRANSPORT WITHIN THE COLD CONVEYOR BELT TO THE NORTH OF THE SFC LOW. THIS IS HEAVIER BAND 1 OF 2 THAT THE RAP HAS FOR SE MN...WITH TOTAL QPF FROM BLUE EARTH...UP THROUGH DODGE CENTER...LAKE CITY...AND EAU CLAIRE BETWEEN 0.85" AND 0.95"...WHICH RESULTS IN A FAIRLY HEALTHY REGION OF 8 TO 10 INCHES OF SNOW. BAND 2 MENTIONED ABOVE SETS UP JUST EAST OF THE FIRST BAND LATER TONIGHT AND WILL PRIMARILY IMPACT THE ARX AREA. THIS BAND IS ASSOCIATED WITH PV ADVECTION TO THE WEST OF THE MAIN PV ANOMALY WHICH THE RAP TAKES FROM AROUND IOWA CITY UP TOWARD WAUSAU. THE 11.23 RAP HAS SLIGHTLY HIGHER QPF AMOUNTS UP AROUND 1 INCH IN THIS AREA...WHICH WOULD INDICATE THE POTENTIAL FOR AMOUNTS OF A FOOT OR MORE. WHAT MAKES THIS A TRICKY SYSTEM TO FORECAST IS THE VERY TIGHT GRADIENT IN SNOWFALL AND AMOUNTS THAT IS EXPECTED TO THE NORTHWEST OF THE HEAVY BAND OF SNOW. FOR INSTANCE...ACROSS GOODHUE COUNTY...LATEST UPDATE TO GRIDS HAS AROUND 8 INCHES ALONG THE WABASHA COUNTY LINE IN THE SOUTH...WITH AMOUNTS NEAR 4 INCHES ALONG THE DAKOTA COUNTY LINE TO THE NORTH. WITH THE SLIGHT NORTHWESTWARD SHIFT IN THE HEAVIER SNOW AMOUNTS...THIS PULLED THE 6+ INCH AMOUNTS A LITTLE FARTHER NORTHWEST. FOR THE COUNTIES ADDED /WASECA...STEELE...GOODHUE...PIERCE...DUNN...AND CHIPPEWA WI/...IT IS BASICALLY THE SOUTHEAST HALF OR LESS OF THESE COUNTIES WHERE AMOUNTS OF 6 INCHES OR MORE ARE EXPECTED. WITH THE TIGHT GRADIENT IN SNOW...DID NOT SEE THE NEED TO ADD ANY COUNTIES TO AN ADVY. FOR EXAMPLE...IN DAKOTA COUNTY...HAVE SNOWFALL AMOUNTS RANGING FROM A TRACE ALONG THE HENNEPIN/RAMSEY COUNTY LINE TO NEAR 4 INCHES ALONG THE GOODHUE COUNTY LINE. OTHER COUNTIES BORDERING THE WARNING SHOW SIMILAR GRADIENTS...SO DID NOT ADD ANY COUNTIES TO AN ADVY. IF ANYTHING...COUNTIES STILL IN THE ADVY WILL BE CLOSE TO WARNING TYPE SNOWS IN THE FAR SOUTHEAST TIPS OF THOSE COUNTIES. KIND OF AN ALL OR NOTHING SCENARIO HERE! WILL BE SEEING SOME INTENSE SNOWFALL RATES TONIGHT ON THE ORDER OF 1 TO 2 INCHES PER HOUR AS WELL /SEE NESDIS SATELLITE PRECIP ESTIMATE PRODUCT AND SPC MESO DISCUSSION #269/. BY MONDAY MORNING...THE INTENSE SNOWFALL WILL START LETTING UP...WITH LIGHT SNOW LINGERING INTO THE AFTERNOON...ESPECIALLY ACROSS WI. SNOW WILL LIKELY CONTINUE BEYOND CURRENT END TIME OF HEADLINES...THOUGH ACCUMULATING SNOWS SHOULD BE ALL BUT DONE BY NOON...BUT A POSSIBLE EXTENSION IN TIME WILL NEED TO BE CONSIDERED BY LATER SHIFTS. BEHIND THIS SYSTEM...IT WILL BE COOL THROUGH THE MIDDLE OF THE WEEK AS HIGH PRESSURE SETTLES IN. TUESDAY LOOKS TO BE THE COLDEST DAY NEXT WEEK. WITH THE COLD UPPER TROUGH OVERHEAD...THIS WILL CREATE STEEP LAPSE RATES WITH DAYTIME HEATING AND LIKELY SOME BOUTS OF SNOW SHOWERS...THOUGH NO ACCUMULATIONS ARE EXPECTED. FOR THE SECOND HALF OF THE WEEK...A MODERATION IN TEMPERATURES BACK TOWARD NORMAL /WHICH ARE ALREADY PUSHING 40 ON THE HIGHS/ IS EXPECTED AS UPPER RIDGING BUILDS EAST FROM THE ROCKIES. FOR NEXT WEEKEND AND BEYOND...THERE IS NOT MUCH CONFIDENCE IN THE FORECAST AS THE ECMWF AND THE GFS SIT ABOUT 180 DEGS APART FROM EACH OTHER. FOR NEXT WEEKEND INTO THE FOLLOWING WEEK...THE ECMWF HAS THE DEEP THROUGH OVER ERN NOAM...WITH A SHARP RIDGE OVER THE ROCKIES...WHICH OPENS THE DOOR FOR MORE MODIFIED ARCTIC AIR. THE GFS ON THE OTHER HAND GOES RIDGING EAST AND TROUGHING WEST AND BRINGS ANOTHER WARM WET SYSTEM INTO THE UPPER MS VALLEY AT THE END OF NEXT WEEKEND INTO THE FOLLOWING WEEK. BASED ON PAST PERFORMANCE...THE GFS IS LIKELY A BIT TOO AGGRESSIVE WITH BREAKING DOWN THE WRN RIDGE NEXT WEEKEND. && .AVIATION.../06Z TAF ISSUANCE/ HEAVY SNOW WELL UNDER WAY FROM SOUTH CENTRAL MN UP INTO WRN WI. HOWEVER...ONLY EAU WILL HAVE TO DEAL WITH THE BRUNT OF THE SNOW... WITH SNOW BAND MAKING IT NO FURTHER THAN ABOUT 5-10 MILES FROM MSP. BASED ON RAP/NAM HOURLY SNOWFALL FORECASTS...HEAVIEST SNOW HAPPENING NOW...WITH 1/2SM TYPE SNOW NOT LASTING MUCH PAST 7Z. WILL HAVE TO WATCH FOR A SECOND BAND OF HEAVIER SNOW FROM ABOUT 12Z TO 15Z AS MAIN UPPER LOW MOVES INTO CENTRAL WI. THE HRRR HAS BEEN BACK AND FORTH WITH WHERE THIS BAND SETS UP BETWEEN EAU AND BCK...SO JUST LEFT GENERAL MVFR VIS -SN DURING THE MORNING...BUT DEPENDING ON WHERE THIS SECOND BAND SETS UP...THERE COULD BE ANOTHER BOUT OF IFR OR LOWER VIS THERE. EVERYWHERE ELSE IT IS A CIG PROBLEM. AXN HAS FOUND ITSELF JUST WEST OF THE LOW CLOUDS AND IT SHOULD STAY THERE THROUGH MONDAY AFTERNOON. FOR OTHER TERMINALS...HEIGHTS SHOULD BE FAIRLY CONSTANT THROUGH THE NIGHT. SHOULD SEE SOME BREAKS BY MORNING...WITH CATEGORICAL IMPROVEMENTS IN CIGS ACROSS MN BY THE AFTERNOON...BUT THERE IS THE POSSIBILITY THAT ERN MN REMAINS IN MVFR CIGS THROUGH THE DURATION OF THE TAF PERIOD. TOWARD THE END OF THE TAF PERIOD...STRONG WAVE CURRENTLY UP IN ALBERTA WILL DIVE SE INTO MN ON NW FLOW. THIS WILL BRING MVFR CIGS BACK TO WRN MN AFTER 00Z AND THEY WILL BE CLOSE TO AXN/RWF BY THE END OF THIS TAF PERIOD. KMSP...CONFIDENCE IS HIGH THAT FIELD REMAINS IN THE FRONT ROW SEATS WITH ONGOING SNOW STORM JUST TO THE SE. FLIGHTS ON APPROACH FOR THE 12S WILL LIKELY BE COMING THROUGH SNOW ON THEIR WAY IN...BUT NOT EXPECTING ANYTHING WORSE THAN A FEW FLURRIES FOR THE FIELD. CIGS WILL BE FLIRTING WITH 017 THROUGH THE REST OF TONIGHT...BUT THEY SHOULD REMAIN ABOVE THIS LEVEL. CONFIDENCE IS LOW IN CLEARING TOMORROW AFTERNOON...WITH IT VERY PLAUSIBLE THAT MVFR CIGS NEVER BECOME BETTER THAN BKN BEFORE CLOUDS FROM NW SYSTEM SHOW UP. FOR WINDS...SPEEDS WILL BE FAIRLY CONSISTENT IN THE 10-15 KT RANGE WITH A SLOW BACKING TOWARD THE WEST THIS PERIOD. /OUTLOOK FOR KMSP/ TUE...MVFR CIGS/VSBYS POSSIBLE WITH -SN. NW WIND 15G25KTS. WED...VFR. NW WIND 5 TO 10 KTS BACKING TO SW. THU...VFR. S WIND AROUND 5 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL 7 AM CDT MONDAY FOR FARIBAULT- FREEBORN-GOODHUE-STEELE-WASECA. WINTER WEATHER ADVISORY UNTIL 7 AM CDT MONDAY FOR BLUE EARTH- MARTIN-RICE. WI...WINTER STORM WARNING UNTIL 10 AM CDT MONDAY FOR CHIPPEWA-DUNN- EAU CLAIRE-PEPIN-PIERCE. WINTER WEATHER ADVISORY UNTIL 10 AM CDT MONDAY FOR RUSK. && $$ MPG/MPG
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
634 PM CDT TUE MAR 12 2013 .AVIATION... 00Z TAFS FOR KOMA...KOFK...KLNK VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. BKN SC DECK AT ALL 3 SITES WILL BE EXITING THIS EVENING...FIRST AT LNK AND THEN OFK AND OMA BY AROUND 07Z. SOME SCT FLURRIES REMAIN POSSIBLE AT OMA FOR ANOTHER HOUR OR TWO...BUT NO ACCUMULATION IS EXPECTED. THE WINDS WILL ALSO BE DIMINISHING THIS EVENING WITH HIGH PRESSURE MOVING OVER. WINDS WILL INCREASE FROM THE AND SOUTHWEST ON WEDNESDAY WITH SOME MID LEVEL CLOUDS. && .PREV DISCUSSION... /ISSUED 325 PM CDT TUE MAR 12 2013/ SHORT TERM...TONIGHT THROUGH FRIDAY. MOSTLY CLOUDY CONDITIONS HAD DEVELOPED THROUGH THE DAY IN THE NORTHEASTERN 2/3 OF THE FORECAST AREA...WITHIN AN AREA CYCLONIC NORTHWESTERLY FLOW AROUND STRONG CLOSED LOW PRESSURE ACROSS THE WESTERN GREAT LAKES. A FEW FLURRIES HAD DEVELOPED IN NORTHEAST NEBRASKA AND NORTHWEST IOWA...BUT MORE IMPORTANTLY...WINDS GUSTING 30 TO 35 MPH HAS ALSO CREATED AREAS OF BLOWING SNOW OUT IN OPEN RURAL AREAS. THIS WAS CREATING SOME VISIBILITY ISSUES...AS WELL AS SOME SLICK ROADWAYS. THIS TREND WILL CONTINUE THROUGH EARLY EVENING UNTIL THE WINDS BEGIN TO DIMINISH BY 5 TO 7 PM...ALTHOUGH ISOLATED FLURRIES COULD STILL BE POSSIBLE IN WESTERN IOWA FOR ANOTHER HOUR OR TWO BEYOND THAT. CLOUD TRENDS OVERNIGHT WILL BE ALSO BE TRICKY TO FORECAST. SURFACE HIGH PRESSURE RIDGE WILL CONTINUE MOVING IN FROM THE WEST. THIS WILL ALLOW SOME OF THE DIURNAL CLOUDS TO DISSIPATE ON THE SOUTHWEST EDGE...HOWEVER AS WITH PAST SEVERAL SYSTEMS...THE RAP SEEMS TO HAVE A MUCH BETTER HANDLE ON THE LOW LEVEL CLOUDINESS...LINGERING IT MUCH LONGER THAN OTHER MODELS WOULD SUGGEST. THIS COULD ALSO AFFECT HOURLY TEMPERATURES...AS SKIES CLEAR IN SOME AREAS AND WINDS BECOME LIGHT AND PERHAPS EVEN CALM IN OUR WESTERN CWA. SOME CIRRUS COULD ALSO BEGIN TO MOVE INTO THESE SAME AREAS TOWARD DAYBREAK...AS AREAS ALONG/EAST OF THE MISSOURI RIVER FINALLY BEGIN TO SCATTER OUT. SOUTHEASTERLY SURFACE FLOW DEVELOPS ON WEDNESDAY AS THE MID/HIGH CLOUDS MOVE ACROSS THE REGION. TEMPS SHOULD WARM INTO THE MID 30S OVER THE SNOWFIELD, AND THE LOWER/MID 40S ELSEWHERE. MEANWHILE...WARM AIR ADVECTION ALOFT WILL CONTINUE THROUGH THE REMAINDER OF THE PERIOD. ANOTHER WEAK CLIPPER SYSTEM WILL MOVE THROUGH THE DAKOTAS WEDNESDAY NIGHT. WHILE THIS COULD GENERATE A SPRINKLE OR TWO IN OUR AREA AND MAYBE EVEN MEASURABLE PRECIP JUST TO OUR NORTH/NORTHEAST...WILL MAINTAIN A DRY FORECAST AT THIS TIME WITH PARTLY TO MOSTLY CLOUDY SKIES EXPECTED. THIS SHOULD TRANSLATE TO DECENT WARMING ON THURSDAY...UPPER 40S OVER THE DIMINISHING SNOW PACK...WHICH IS STILL UNDER MAV/MET GUIDANCE... TO THE LOWER 60S OVER THE SNOW FREE AREAS. FRIDAY SHOULD BE THE WARMEST DAY OF THE WEEK AS TEMPERATURES WARM SIGNIFICANTLY AHEAD OF THE NEXT COLD FRONT EXPECTED FOR THE WEEKEND. TEMPS FRIDAY SHOULD REACH THE MID 50S WHERE SOME SNOW STILL EXISTS...AND EVEN IN THE MID TO UPPER 60S ELSEWHERE. DEWALD LONG TERM...FRIDAY NIGHT THROUGH TUESDAY. THE EXTENDED PERIOD LOOKS TO BE A PERIOD OF BELOW NORMAL TEMPERATURES WITH UNSETTLED WEATHER SATURDAY THROUGH MONDAY. WEATHER DISTURBANCES MOVING THROUGH THE WEST AND NORTHWEST FLOW ALOFT AND WILL BRING CHANCES OF PRECIPITATION. THE LONG RANGE MODELS ARE NOT IN GOOD AGREEMENT IN SPECIFIC TIMING AND STRENGTH OF THE SYSTEMS...THUS LOW CONFIDENCE IN PINNING DOWN THE THERMAL STRUCTURE AND TIMING. A WEAK WAVE APPEARS TO MOVE THROUGH THE CENTRAL/NORTHER PLAINS SATURDAY AND SATURDAY NIGHT...AND THE GFS LINGERS IT INTO SUNDAY...WITH SNOW...SLEET...AND RAIN POSSIBLE. SUNDAY NIGHT INTO MONDAY...ANOTHER STRONGER SYSTEM MOVES THROUGH. THE EC IS STRONGER WITH THE WAVE...FARTHER NORTH WITH THE PRECIP AND MOVES IT THROUGH FASTER WITH MORE COLD AIR AND STRONGER WINDS AVAILABLE. FOR NOW HAVE CHANCE POPS FOR RAIN OR SNOW MENTIONED FOR SUNDAY NIGHT AND MONDAY. ZAPOTOCNY && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1242 PM CDT MON MAR 11 2013 .SYNOPSIS... ISSUED AT 404 AM CDT MON MAR 11 2013 WATER VAPOR IMAGERY AT 08Z SHOWED A DEEP TROUGH OVER THE CENTRAL CONUS WHICH EXTENDED INTO BAJA CALIFORNIA...WITH THE UPPER LEVEL LOW CENTERED OVER IOWA. SNOW CONTINUED TO FALL WITH THIS SYSTEM OVER EASTERN NEBRASKA EARLY THIS MORNING...HOWEVER MOST IMPACTS HAD SHIFTED EAST OF THE STATE. STRONG RIDGING WAS OBSERVED DOWNSTREAM OVER THE EAST COAST...WHILE ANOTHER BROAD RIDGE WAS SEEN OVER THE EASTERN PACIFIC AND WESTERN CONUS. THERE WAS A WEAK SHORTWAVE TROUGH OVER MONTANA THIS MORNING AS TOP OF THE RIDGE WAS FAIRLY FLATTENED. AT THE SURFACE...THE PRESSURE GRADIENT HAD FINALLY WEAKENED AS THE SURFACE LOW WITH THE SYSTEM TO THE EAST PULLED OFF INTO ILLINOIS AND WISCONSIN. THIS LEFT WINDS TO DIMINISH OVERNIGHT...WHILE A SURFACE TROUGH WAS ANALYZED ON THE LEE SIDE OF THE ROCKIES WITH BREEZY WESTERLY WINDS IN ITS WAKE. WITH WEAK HIGH PRESSURE OVER THE FORECAST AREA...TEMPERATURES OVERNIGHT HAVE DROPPED SIGNIFICANTLY...INTO THE SINGLE DIGITS AND TEENS. && .UPDATE... ISSUED AT 1107 AM CDT MON MAR 11 2013 INCREASED MAX TEMPERATURES TODAY ACROSS MY SOUTHEAST ZONES INTO THE UPPER 40S. TEMPERATURES HAVE QUICKLY WARMED THIS MORNING IN AREAS OF MINIMAL SNOW COVER. DID NOT TAKE AN AGGRESSIVE APPROACH WITH CONTINUED WARMING THIS AFTERNOON SINCE NORTHWEST WINDS WILL MOVE OVER THE DENSE SNOW PACK FROM OGA TO VTN...WHICH MAY HAMPER TEMPERATURES BY A FEW DEGREES. ALSO ADJUSTED POP FIELDS FOR THIS AFTERNOON AND EVENING. H7 FRONT SHOWING UP WELL ON IR SATELLITE...EXTENDING FROM CENTRAL MONTANA SOUTHEAST INTO NORTHEAST COLORADO. EXPECT THIS TO BE THE PRIMARY FOCUS FOR SNOW SHOWERS LATER TODAY INTO THE OVERNIGHT HOURS AS COLDER AIR MOVES SOUTH IN ADVANCE OF THE SHORTWAVE TROUGH CURRENTLY IN EASTERN MONTANA. UPDATE ISSUED AT 715 AM CDT MON MAR 11 2013 A NEW FORECAST IS OUT. LOOKING AT THE RAP MODEL SOUNDINGS AND THE K INDEXES OF ALL MODELS SUGGESTS REASONABLE POTENTIAL FOR CONVECTION THIS AFTERNOON...MAINLY OFF THE BLACK HILLS AND IN THE PANHANDLE WHERE MOISTURE WILL BE DEEPEST AND LAPSE RATES STEEPEST. WE MAY EVEN SEE A BREAKAWAY STORM MOVE AS FAR SOUTH AS I-80 LATE THIS AFTN OR THIS EVENING. THE NAM INDICATED POTENTIAL FOR TSTMS BUT GIVEN THE ISOLATED COVERAGE IT IS PROBABLY NOT WORTH MENTION. OTHERWISE RAIN AND SNOW SHOWERS UNTIL EARLY EVENING THEN SNOW SHOWERS. WINDS STAY UP TONIGHT SO LOWS SHOULD BE IN THE 20S MOST AREAS. THE MODELS ARE SUGGESTING A BLEND OF PACIFIC AND ARCTIC MOVING IN TONIGHT AND HOLDING ON THROUGH TUESDAY. HIGH TEMPERATURES TUESDAY HAVE BEEN MARKED DOWN TO 30S TO LOWER 40S AS SUGGESTED BY A MULTIMODEL BLEND OF BIAS DATA. WINDS TODAY AND TUESDAY WILL REACH 20 TO 30 MPH...ACROSS THE WEST TODAY AND THE NORTHEAST TUESDAY. && .SHORT TERM...(TODAY THROUGH MONDAY NIGHT) ISSUED AT 404 AM CDT MON MAR 11 2013 A MULTIMODEL BLEND OF THE GEM...NAM...GFS AND ECM WHICH ARE ALL PRETTY CLOSE WITH LOW PRESSURE DROPPING THROUGH THE MISSOURI BASIN SETTING OFF ISOLATED RAIN OR SNOW SHOWERS THIS AFTERNOON. FARTHER WEST...LAPSE RATES STEEPEN LATE THIS AFTERNOON AND THIS EVENING. A COLD FRONT DROPS THROUGH THE HIGH PLAINS ACTING AS A FOCUS FOR RAIN AND SNOW SHOWERS. WINDS INCREASE TO 15 TO 30 MPH THIS AFTERNOON AND REMAIN SUFFICIENTLY STRONG TO PREVENT THE DEVELOPMENT OF A SFC INVERSION TONIGHT. SO TEMPS TONIGHT SHOULD REMAIN MOSTLY IN THE 20S...A FEW TEENS IN THE NORTHWEST WHERE HIGH PRESSURE WILL SETTLE IN SOMEWHAT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 404 AM CDT MON MAR 11 2013 THE FORECAST FOCUS THROUGH THIS PERIOD IS WITH TEMPERATURES...AS WELL AS PRECIPITATION CHANCES THROUGH THE WEEKEND. THE TUESDAY THROUGH FRIDAY PERIOD IS FAIRLY STRAIGHT FORWARD THIS FORECAST CYCLE AS MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE UPPER LEVEL PATTERN AND SURFACE FEATURES. THE RIDGE OFF THE EAST COAST WILL STAY FIRMLY IN PLACE THROUGH MID-WEEK WHICH WILL KEEP AN UPPER LEVEL TROUGH CENTERED OVER THE MISSISSIPPI AND OHIO VALLEYS. MEANWHILE...ENERGY ASSOCIATED WITH THE SHORTWAVE TROUGH CURRENTLY OVER MONTANA WILL BE MOVING OUT OF THE NORTHERN AND CENTRAL PLAINS ON TUESDAY AND INTO THE PRIMARY TROUGH TO THE EAST. ANY PRECIPITATION EXPECTED FOR MONDAY NIGHT SHOULD END BY TUESDAY MORNING AS ANY FORCING FOR PRECIPITATION DEVELOPMENT WANES ACROSS THE LOCAL AREA. ALTHOUGH THE FORECAST AREA WILL BE IN NORTHWEST FLOW BEHIND THIS SHORTWAVE...SLIGHT WARM AIR ADVECTION WILL BE ONGOING THROUGH THE DAY...AND WITH SKIES EXPECTED TO CLEAR AS HIGH PRESSURE BUILD IN...TEMPERATURES WILL BE ON A WARMING TREND. SHOULD STILL SEE IMPACTS ON HIGHS ON TUESDAY FROM THE SNOWPACK...WHICH IS QUITE SUBSTANTIAL IN PARTS OF THE FORECAST AREA. THE UPPER LEVEL TROUGH OVER THE OHIO VALLEY WILL FINALLY SHIFT FURTHER EASTWARD THROUGH THURSDAY ALLOWING THE RIDGE OVER THE WEST TO BUILD INTO THE PLAINS. THIS WILL BRING SIGNIFICANT WARM AIR ADVECTION TO THE REGION AS TEMPERATURES AT 850MB ARE BEING SHOWN TO RISE INTO THE MID AND UPPER TEENS BY FRIDAY EVENING. SNOW MELT WILL BE IN FULL SWING BY WEDNESDAY AND BY THURSDAY AND FRIDAY DON/T EXPECT MUCH IMPACT ON TEMPERATURES. ALTHOUGH MODELS AREN/T SHOWING REAL STRONG WINDS WEDNESDAY THROUGH FRIDAY...THOUGHTS ARE THAT WITH THE WARMING EXPECTED...WILL GET DECENT MIXING TO BRING DOWN SOME STRONGER WINDS FROM ALOFT SO DID INCREASE THE WIND SPEEDS SLIGHTLY. DIDN/T GO QUITE AS WARM AS SOME MODELS WOULD SUGGEST...AS SOME GUIDANCE WAS GIVING MID TO UPPER 70S FOR FRIDAY. STUCK WITH UPPER 50S AND 60S FOR THURSDAY AND 60S TO LOW 70S FOR FRIDAY. THINGS WILL COOL OFF FOR THE WEEKEND AS THE MODELS ARE SHOWING A SWITCH IN THE UPPER LEVEL PATTERN. THIS BEING SAID...THERE ARE CONSIDERABLE DIFFERENCES IN THE MODEL SOLUTIONS THROUGH THE WEEKEND SO CONFIDENCE ON THIS PORTION OF THE FORECAST IS FAIRLY LOW. THERE LOOKS TO BE A CHANCE FOR SOME PRECIPITATION ACROSS THE AREA AT SOME POINT DURING THE WEEKEND...BUT WITH THE INCONSISTENCIES AND LOW CONFIDENCE IN MODEL SOLUTIONS...TRIED TO PICK OUT THE PERIODS AND LOCATIONS WITH THE HIGHER PROBABILITIES TO INCLUDE PRECIPITATION CHANCES IN THE FORECAST AT THIS POINT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1245 PM CDT MON MAR 11 2013 NO AVIATION CONCERNS OVER THE NEXT 24 HOURS. CONDITIONS WILL REMAIN VFR ACROSS MOST OF WESTERN NEBRASKA. SNOW SHOWERS WILL BE POSSIBLE IN THE EASTERN PANHANDLE AND FAR SOUTHWEST NEBRASKA THIS EVENING AND TONIGHT...WHICH MAY CLIP KLBF. DUE TO LOW FORECASTER CONFIDENCE HAVE LEFT ANY MENTION OF -SN OUT OF THE TAF FOR NOW. MONITORING POSSIBILITY OF FOG AT KVTN OVERNIGHT ON TOP OF FRESH SNOW PACK. HOWEVER WINDS ARE EXPECTED TO REMAIN ELEVATED THROUGH THE OVERNIGHT HOURS WHICH WOULD ALL BUT ELIMINATE CHANCES OF FOG FORMATION. TRENDS WILL BE MONITORED AND AMENDMENTS WILL BE MADE IF NECESSARY. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...MARTIN SYNOPSIS...BROOKS SHORT TERM...CDC LONG TERM...BROOKS AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1108 AM CDT MON MAR 11 2013 .SYNOPSIS... ISSUED AT 404 AM CDT MON MAR 11 2013 WATER VAPOR IMAGERY AT 08Z SHOWED A DEEP TROUGH OVER THE CENTRAL CONUS WHICH EXTENDED INTO BAJA CALIFORNIA...WITH THE UPPER LEVEL LOW CENTERED OVER IOWA. SNOW CONTINUED TO FALL WITH THIS SYSTEM OVER EASTERN NEBRASKA EARLY THIS MORNING...HOWEVER MOST IMPACTS HAD SHIFTED EAST OF THE STATE. STRONG RIDGING WAS OBSERVED DOWNSTREAM OVER THE EAST COAST...WHILE ANOTHER BROAD RIDGE WAS SEEN OVER THE EASTERN PACIFIC AND WESTERN CONUS. THERE WAS A WEAK SHORTWAVE TROUGH OVER MONTANA THIS MORNING AS TOP OF THE RIDGE WAS FAIRLY FLATTENED. AT THE SURFACE...THE PRESSURE GRADIENT HAD FINALLY WEAKENED AS THE SURFACE LOW WITH THE SYSTEM TO THE EAST PULLED OFF INTO ILLINOIS AND WISCONSIN. THIS LEFT WINDS TO DIMINISH OVERNIGHT...WHILE A SURFACE TROUGH WAS ANALYZED ON THE LEE SIDE OF THE ROCKIES WITH BREEZY WESTERLY WINDS IN ITS WAKE. WITH WEAK HIGH PRESSURE OVER THE FORECAST AREA...TEMPERATURES OVERNIGHT HAVE DROPPED SIGNIFICANTLY...INTO THE SINGLE DIGITS AND TEENS. && .UPDATE... ISSUED AT 1107 AM CDT MON MAR 11 2013 INCREASED MAX TEMPERATURES TODAY ACROSS MY SOUTHEAST ZONES INTO THE UPPER 40S. TEMPERATURES HAVE QUICKLY WARMED THIS MORNING IN AREAS OF MINIMAL SNOW COVER. DID NOT TAKE AN AGGRESSIVE APPROACH WITH CONTINUED WARMING THIS AFTERNOON SINCE NORTHWEST WINDS WILL MOVE OVER THE DENSE SNOW PACK FROM OGA TO VTN...WHICH MAY HAMPER TEMPERATURES BY A FEW DEGREES. ALSO ADJUSTED POP FIELDS FOR THIS AFTERNOON AND EVENING. H7 FRONT SHOWING UP WELL ON IR SATELLITE...EXTENDING FROM CENTRAL MONTANA SOUTHEAST INTO NORTHEAST COLORADO. EXPECT THIS TO BE THE PRIMARY FOCUS FOR SNOW SHOWERS LATER TODAY INTO THE OVERNIGHT HOURS AS COLDER AIR MOVES SOUTH IN ADVANCE OF THE SHORTWAVE TROUGH CURRENTLY IN EASTERN MONTANA. UPDATE ISSUED AT 715 AM CDT MON MAR 11 2013 A NEW FORECAST IS OUT. LOOKING AT THE RAP MODEL SOUNDINGS AND THE K INDEXES OF ALL MODELS SUGGESTS REASONABLE POTENTIAL FOR CONVECTION THIS AFTERNOON...MAINLY OFF THE BLACK HILLS AND IN THE PANHANDLE WHERE MOISTURE WILL BE DEEPEST AND LAPSE RATES STEEPEST. WE MAY EVEN SEE A BREAKAWAY STORM MOVE AS FAR SOUTH AS I-80 LATE THIS AFTN OR THIS EVENING. THE NAM INDICATED POTENTIAL FOR TSTMS BUT GIVEN THE ISOLATED COVERAGE IT IS PROBABLY NOT WORTH MENTION. OTHERWISE RAIN AND SNOW SHOWERS UNTIL EARLY EVENING THEN SNOW SHOWERS. WINDS STAY UP TONIGHT SO LOWS SHOULD BE IN THE 20S MOST AREAS. THE MODELS ARE SUGGESTING A BLEND OF PACIFIC AND ARCTIC MOVING IN TONIGHT AND HOLDING ON THROUGH TUESDAY. HIGH TEMPERATURES TUESDAY HAVE BEEN MARKED DOWN TO 30S TO LOWER 40S AS SUGGESTED BY A MULTIMODEL BLEND OF BIAS DATA. WINDS TODAY AND TUESDAY WILL REACH 20 TO 30 MPH...ACROSS THE WEST TODAY AND THE NORTHEAST TUESDAY. && .SHORT TERM...(TODAY THROUGH MONDAY NIGHT) ISSUED AT 404 AM CDT MON MAR 11 2013 A MULTIMODEL BLEND OF THE GEM...NAM...GFS AND ECM WHICH ARE ALL PRETTY CLOSE WITH LOW PRESSURE DROPPING THROUGH THE MISSOURI BASIN SETTING OFF ISOLATED RAIN OR SNOW SHOWERS THIS AFTERNOON. FARTHER WEST...LAPSE RATES STEEPEN LATE THIS AFTERNOON AND THIS EVENING. A COLD FRONT DROPS THROUGH THE HIGH PLAINS ACTING AS A FOCUS FOR RAIN AND SNOW SHOWERS. WINDS INCREASE TO 15 TO 30 MPH THIS AFTERNOON AND REMAIN SUFFICIENTLY STRONG TO PREVENT THE DEVELOPMENT OF A SFC INVERSION TONIGHT. SO TEMPS TONIGHT SHOULD REMAIN MOSTLY IN THE 20S...A FEW TEENS IN THE NORTHWEST WHERE HIGH PRESSURE WILL SETTLE IN SOMEWHAT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 404 AM CDT MON MAR 11 2013 THE FORECAST FOCUS THROUGH THIS PERIOD IS WITH TEMPERATURES...AS WELL AS PRECIPITATION CHANCES THROUGH THE WEEKEND. THE TUESDAY THROUGH FRIDAY PERIOD IS FAIRLY STRAIGHT FORWARD THIS FORECAST CYCLE AS MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE UPPER LEVEL PATTERN AND SURFACE FEATURES. THE RIDGE OFF THE EAST COAST WILL STAY FIRMLY IN PLACE THROUGH MID-WEEK WHICH WILL KEEP AN UPPER LEVEL TROUGH CENTERED OVER THE MISSISSIPPI AND OHIO VALLEYS. MEANWHILE...ENERGY ASSOCIATED WITH THE SHORTWAVE TROUGH CURRENTLY OVER MONTANA WILL BE MOVING OUT OF THE NORTHERN AND CENTRAL PLAINS ON TUESDAY AND INTO THE PRIMARY TROUGH TO THE EAST. ANY PRECIPITATION EXPECTED FOR MONDAY NIGHT SHOULD END BY TUESDAY MORNING AS ANY FORCING FOR PRECIPITATION DEVELOPMENT WANES ACROSS THE LOCAL AREA. ALTHOUGH THE FORECAST AREA WILL BE IN NORTHWEST FLOW BEHIND THIS SHORTWAVE...SLIGHT WARM AIR ADVECTION WILL BE ONGOING THROUGH THE DAY...AND WITH SKIES EXPECTED TO CLEAR AS HIGH PRESSURE BUILD IN...TEMPERATURES WILL BE ON A WARMING TREND. SHOULD STILL SEE IMPACTS ON HIGHS ON TUESDAY FROM THE SNOWPACK...WHICH IS QUITE SUBSTANTIAL IN PARTS OF THE FORECAST AREA. THE UPPER LEVEL TROUGH OVER THE OHIO VALLEY WILL FINALLY SHIFT FURTHER EASTWARD THROUGH THURSDAY ALLOWING THE RIDGE OVER THE WEST TO BUILD INTO THE PLAINS. THIS WILL BRING SIGNIFICANT WARM AIR ADVECTION TO THE REGION AS TEMPERATURES AT 850MB ARE BEING SHOWN TO RISE INTO THE MID AND UPPER TEENS BY FRIDAY EVENING. SNOW MELT WILL BE IN FULL SWING BY WEDNESDAY AND BY THURSDAY AND FRIDAY DON/T EXPECT MUCH IMPACT ON TEMPERATURES. ALTHOUGH MODELS AREN/T SHOWING REAL STRONG WINDS WEDNESDAY THROUGH FRIDAY...THOUGHTS ARE THAT WITH THE WARMING EXPECTED...WILL GET DECENT MIXING TO BRING DOWN SOME STRONGER WINDS FROM ALOFT SO DID INCREASE THE WIND SPEEDS SLIGHTLY. DIDN/T GO QUITE AS WARM AS SOME MODELS WOULD SUGGEST...AS SOME GUIDANCE WAS GIVING MID TO UPPER 70S FOR FRIDAY. STUCK WITH UPPER 50S AND 60S FOR THURSDAY AND 60S TO LOW 70S FOR FRIDAY. THINGS WILL COOL OFF FOR THE WEEKEND AS THE MODELS ARE SHOWING A SWITCH IN THE UPPER LEVEL PATTERN. THIS BEING SAID...THERE ARE CONSIDERABLE DIFFERENCES IN THE MODEL SOLUTIONS THROUGH THE WEEKEND SO CONFIDENCE ON THIS PORTION OF THE FORECAST IS FAIRLY LOW. THERE LOOKS TO BE A CHANCE FOR SOME PRECIPITATION ACROSS THE AREA AT SOME POINT DURING THE WEEKEND...BUT WITH THE INCONSISTENCIES AND LOW CONFIDENCE IN MODEL SOLUTIONS...TRIED TO PICK OUT THE PERIODS AND LOCATIONS WITH THE HIGHER PROBABILITIES TO INCLUDE PRECIPITATION CHANCES IN THE FORECAST AT THIS POINT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 620 AM CDT MON MAR 11 2013 VFR IS GENERALLY EXPECTED TODAY AND TONIGHT AS A MIX OF MID AND HIGH CLOUDS MOVE SOUTHEAST OFF THE HIGH PLAINS. THERE IS OPPORTUNITY FOR MVFR CIGS IN ISOLATED TO SCATTERED RAIN AND SNOW SHOWERS...MAINLY LATE THIS AFTERNOON AND THIS EVENING ACROSS NRN AND WRN NEB. THE MODELS OFFER SOME DIVERSE SOLNS TO THIS EVENT. SOME DEVELOP CONVECTION ACROSS NRN NEB AROUND NOON WHILE OTHERS WAIT TILL LATE AFTERNOON AND SOME SOLNS SHOW NO CONVECTION AT ALL ACROSS NRN NEB. THERE IS A GOOD CONSENSUS FOR ACTIVITY DEVELOPING OFF THE BLACK HILLS LATE THIS AFTERNOON AND ACROSS THE NEB PANHANDLE. THIS ACTIVITY WILL MOVE SOUTH SOUTHEAST. IN FACT THERE COULD EVEN BE AN ISOLATED LIGHTNING STRIKE OR TWO ACROSS SHERIDAN AND CHERRY COUNTIES LATE THIS AFTERNOON. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...MARTIN SYNOPSIS...BROOKS SHORT TERM...CDC LONG TERM...BROOKS AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
724 AM CDT MON MAR 11 2013 .SYNOPSIS... ISSUED AT 404 AM CDT MON MAR 11 2013 WATER VAPOR IMAGERY AT 08Z SHOWED A DEEP TROUGH OVER THE CENTRAL CONUS WHICH EXTENDED INTO BAJA CALIFORNIA...WITH THE UPPER LEVEL LOW CENTERED OVER IOWA. SNOW CONTINUED TO FALL WITH THIS SYSTEM OVER EASTERN NEBRASKA EARLY THIS MORNING...HOWEVER MOST IMPACTS HAD SHIFTED EAST OF THE STATE. STRONG RIDGING WAS OBSERVED DOWNSTREAM OVER THE EAST COAST...WHILE ANOTHER BROAD RIDGE WAS SEEN OVER THE EASTERN PACIFIC AND WESTERN CONUS. THERE WAS A WEAK SHORTWAVE TROUGH OVER MONTANA THIS MORNING AS TOP OF THE RIDGE WAS FAIRLY FLATTENED. AT THE SURFACE...THE PRESSURE GRADIENT HAD FINALLY WEAKENED AS THE SURFACE LOW WITH THE SYSTEM TO THE EAST PULLED OFF INTO ILLINOIS AND WISCONSIN. THIS LEFT WINDS TO DIMINISH OVERNIGHT...WHILE A SURFACE TROUGH WAS ANALYZED ON THE LEE SIDE OF THE ROCKIES WITH BREEZY WESTERLY WINDS IN ITS WAKE. WITH WEAK HIGH PRESSURE OVER THE FORECAST AREA...TEMPERATURES OVERNIGHT HAVE DROPPED SIGNIFICANTLY...INTO THE SINGLE DIGITS AND TEENS. && .UPDATE... ISSUED AT 715 AM CDT MON MAR 11 2013 A NEW FORECAST IS OUT. LOOKING AT THE RAP MODEL SOUNDINGS AND THE K INDEXES OF ALL MODELS SUGGESTS REASONABLE POTENTIAL FOR CONVECTION THIS AFTERNOON...MAINLY OFF THE BLACK HILLS AND IN THE PANHANDLE WHERE MOISTURE WILL BE DEEPEST AND LAPSE RATES STEEPEST. WE MAY EVEN SEE A BREAKAWAY STORM MOVE AS FAR SOUTH AS I-80 LATE THIS AFTN OR THIS EVENING. THE NAM INDICATED POTENTIAL FOR TSTMS BUT GIVEN THE ISOLATED COVERAGE IT IS PROBABLY NOT WORTH MENTION. OTHERWISE RAIN AND SNOW SHOWERS UNTIL EARLY EVENING THEN SNOW SHOWERS. WINDS STAY UP TONIGHT SO LOWS SHOULD BE IN THE 20S MOST AREAS. THE MODELS ARE SUGGESTING A BLEND OF PACIFIC AND ARCTIC MOVING IN TONIGHT AND HOLDING ON THROUGH TUESDAY. HIGH TEMPERATURES TUESDAY HAVE BEEN MARKED DOWN TO 30S TO LOWER 40S AS SUGGESTED BY A MULTIMODEL BLEND OF BIAS DATA. WINDS TODAY AND TUESDAY WILL REACH 20 TO 30 MPH...ACROSS THE WEST TODAY AND THE NORTHEAST TUESDAY. && .SHORT TERM...(TODAY THROUGH MONDAY NIGHT) ISSUED AT 404 AM CDT MON MAR 11 2013 A MULTIMODEL BLEND OF THE GEM...NAM...GFS AND ECM WHICH ARE ALL PRETTY CLOSE WITH LOW PRESSURE DROPPING THROUGH THE MISSOURI BASIN SETTING OFF ISOLATED RAIN OR SNOW SHOWERS THIS AFTERNOON. FARTHER WEST...LAPSE RATES STEEPEN LATE THIS AFTERNOON AND THIS EVENING. A COLD FRONT DROPS THROUGH THE HIGH PLAINS ACTING AS A FOCUS FOR RAIN AND SNOW SHOWERS. WINDS INCREASE TO 15 TO 30 MPH THIS AFTERNOON AND REMAIN SUFFICIENTLY STRONG TO PREVENT THE DEVELOPMENT OF A SFC INVERSION TONIGHT. SO TEMPS TONIGHT SHOULD REMAIN MOSTLY IN THE 20S...A FEW TEENS IN THE NORTHWEST WHERE HIGH PRESSURE WILL SETTLE IN SOMEWHAT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 404 AM CDT MON MAR 11 2013 THE FORECAST FOCUS THROUGH THIS PERIOD IS WITH TEMPERATURES...AS WELL AS PRECIPITATION CHANCES THROUGH THE WEEKEND. THE TUESDAY THROUGH FRIDAY PERIOD IS FAIRLY STRAIGHT FORWARD THIS FORECAST CYCLE AS MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE UPPER LEVEL PATTERN AND SURFACE FEATURES. THE RIDGE OFF THE EAST COAST WILL STAY FIRMLY IN PLACE THROUGH MID-WEEK WHICH WILL KEEP AN UPPER LEVEL TROUGH CENTERED OVER THE MISSISSIPPI AND OHIO VALLEYS. MEANWHILE...ENERGY ASSOCIATED WITH THE SHORTWAVE TROUGH CURRENTLY OVER MONTANA WILL BE MOVING OUT OF THE NORTHERN AND CENTRAL PLAINS ON TUESDAY AND INTO THE PRIMARY TROUGH TO THE EAST. ANY PRECIPITATION EXPECTED FOR MONDAY NIGHT SHOULD END BY TUESDAY MORNING AS ANY FORCING FOR PRECIPITATION DEVELOPMENT WANES ACROSS THE LOCAL AREA. ALTHOUGH THE FORECAST AREA WILL BE IN NORTHWEST FLOW BEHIND THIS SHORTWAVE...SLIGHT WARM AIR ADVECTION WILL BE ONGOING THROUGH THE DAY...AND WITH SKIES EXPECTED TO CLEAR AS HIGH PRESSURE BUILD IN...TEMPERATURES WILL BE ON A WARMING TREND. SHOULD STILL SEE IMPACTS ON HIGHS ON TUESDAY FROM THE SNOWPACK...WHICH IS QUITE SUBSTANTIAL IN PARTS OF THE FORECAST AREA. THE UPPER LEVEL TROUGH OVER THE OHIO VALLEY WILL FINALLY SHIFT FURTHER EASTWARD THROUGH THURSDAY ALLOWING THE RIDGE OVER THE WEST TO BUILD INTO THE PLAINS. THIS WILL BRING SIGNIFICANT WARM AIR ADVECTION TO THE REGION AS TEMPERATURES AT 850MB ARE BEING SHOWN TO RISE INTO THE MID AND UPPER TEENS BY FRIDAY EVENING. SNOW MELT WILL BE IN FULL SWING BY WEDNESDAY AND BY THURSDAY AND FRIDAY DON/T EXPECT MUCH IMPACT ON TEMPERATURES. ALTHOUGH MODELS AREN/T SHOWING REAL STRONG WINDS WEDNESDAY THROUGH FRIDAY...THOUGHTS ARE THAT WITH THE WARMING EXPECTED...WILL GET DECENT MIXING TO BRING DOWN SOME STRONGER WINDS FROM ALOFT SO DID INCREASE THE WIND SPEEDS SLIGHTLY. DIDN/T GO QUITE AS WARM AS SOME MODELS WOULD SUGGEST...AS SOME GUIDANCE WAS GIVING MID TO UPPER 70S FOR FRIDAY. STUCK WITH UPPER 50S AND 60S FOR THURSDAY AND 60S TO LOW 70S FOR FRIDAY. THINGS WILL COOL OFF FOR THE WEEKEND AS THE MODELS ARE SHOWING A SWITCH IN THE UPPER LEVEL PATTERN. THIS BEING SAID...THERE ARE CONSIDERABLE DIFFERENCES IN THE MODEL SOLUTIONS THROUGH THE WEEKEND SO CONFIDENCE ON THIS PORTION OF THE FORECAST IS FAIRLY LOW. THERE LOOKS TO BE A CHANCE FOR SOME PRECIPITATION ACROSS THE AREA AT SOME POINT DURING THE WEEKEND...BUT WITH THE INCONSISTENCIES AND LOW CONFIDENCE IN MODEL SOLUTIONS...TRIED TO PICK OUT THE PERIODS AND LOCATIONS WITH THE HIGHER PROBABILITIES TO INCLUDE PRECIPITATION CHANCES IN THE FORECAST AT THIS POINT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 620 AM CDT MON MAR 11 2013 VFR IS GENERALLY EXPECTED TODAY AND TONIGHT AS A MIX OF MID AND HIGH CLOUDS MOVE SOUTHEAST OFF THE HIGH PLAINS. THERE IS OPPORTUNITY FOR MVFR CIGS IN ISOLATED TO SCATTERED RAIN AND SNOW SHOWERS...MAINLY LATE THIS AFTERNOON AND THIS EVENING ACROSS NRN AND WRN NEB. THE MODELS OFFER SOME DIVERSE SOLNS TO THIS EVENT. SOME DEVELOP CONVECTION ACROSS NRN NEB AROUND NOON WHILE OTHERS WAIT TILL LATE AFTERNOON AND SOME SOLNS SHOW NO CONVECTION AT ALL ACROSS NRN NEB. THERE IS A GOOD CONSENSUS FOR ACTIVITY DEVELOPING OFF THE BLACK HILLS LATE THIS AFTERNOON AND ACROSS THE NEB PANHANDLE. THIS ACTIVITY WILL MOVE SOUTH SOUTHEAST. IN FACT THERE COULD EVEN BE AN ISOLATED LIGHTNING STRIKE OR TWO ACROSS SHERIDAN AND CHERRY COUNTIES LATE THIS AFTERNOON. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CDC SYNOPSIS...BROOKS SHORT TERM...CDC LONG TERM...BROOKS AVIATION...CDC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
930 PM EDT TUE MAR 12 2013 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO THE CAROLINAS TONIGHT THROUGH THURSDAY. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... AS OF 930 PM TUESDAY... THROUGH TONIGHT: SKIES HAVE CLEARED ACROSS ALL OF CENTRAL NC AS THE COLD FRONT WHICH BROUGHT TODAY`S RAIN HAS SHIFTED TO COASTAL SECTIONS AND IS POISED TO MOVE OFFSHORE... PROPELLED BY COOL HIGH PRESSURE EXTENDING FROM CENTRAL CANADA DOWN THROUGH THE PLAINS AND LOWER MISS VALLEY. THE DIFFERENCE BETWEEN THE 00Z SOUNDINGS AT MHX (SOME LINGERING MOISTURE BELOW 850 MB) AND GSO (VERY DRY AIR THROUGH THE COLUMN) TELLS THE STORY... AS DOES THE WATER VAPOR IMAGERY SHOWING WELL THE SLUG OF DRY AIR SWEEPING TO THE NE THROUGH CENTRAL NC. UPPER LEVEL TRAJECTORIES DO SUGGEST HOWEVER THAT THE HIGH CLOUDS NOW STREAMING ACROSS ARK AND THE MEMPHIS AREA WILL SWEEP ACROSS NC TOWARD MIDNIGHT AND DURING THE OVERNIGHT HOURS... ALSO INDICATED BY THE RAP SOUNDINGS. WILL INCLUDE A THIN VEIL OF CLOUDS OVERNIGHT... BUT OTHERWISE SKIES SHOULD BE CLEAR. AS THE SURFACE RIDGE BUILDS IN OVERNIGHT WITH NORTHEASTERLY SURFACE WINDS AND COLD AIR ADVECTION... THICKNESSES ARE EXPECTED TO PLUMMET... FROM MUCH ABOVE NORMAL READINGS TODAY TO JUST BELOW NORMAL READINGS BY MORNING... ALTHOUGH THE MORE SIGNIFICANT DROP COMES WEDNESDAY INTO WEDNESDAY NIGHT WITH THE ARRIVAL OF THE POLAR FRONT. BOTH TEMPS AND DEW POINTS ARE TRENDING VERY CLOSE TO THE FORECAST PACE... AND LOWS OF 34-42 STILL LOOK REASONABLE. -GIH WEDNESDAY AND WEDNESDAY NIGHT: POTENT SHORTWAVE ENERGY UPSTREAM OVER MINNESOTA WILL DIG SOUTHEAST INTO THE TN VALLEY TONIGHT AND THEN THROUGH THE CAROLINAS AND VIRGINIA ON WEDNESDAY. AS THE POTENT VORTMAX SWINGS THROUGH THE AREA...STRONG DCVA AIDED BY COOLING ALOFT WILL RESULT IN STRONG MID AND UPPER LEVEL ASCENT. AIRMASS WILL BE TOO DRY TO SUPPORT OTHER THAN A PERIOD OF A PERIOD OF BROKEN TO OVERCAST MID CLOUDS WEDNESDAY AFTERNOON. AN ATYPICALLY COLD AIRMASS ALOFT (H85 TEMPS 1-2 STD DEVIATIONS BELOW NORMAL)IN THE PRESENCE OF DEEP VERTICAL MIXING WILL RESULT IN BELOW NORMAL TEMPERATURES WITH BREEZY NWLY WIND GUSTS BETWEEN 20 TO 25KTS. BOTH THE DRY-ADIABATIC AND LOW-LEVEL THICKNESS TEMPERATURES SCHEME SUGGEST AFTERNOON HIGHS A GOOD 5 TO 8 DEGREES BELOW STATISTICAL MOS GUIDANCE. HOWEVER...CONSIDERING THE EVER INCREASING SUN ANGLE THIS TIME OF YEAR...AM CONCERNED CURRENT FORECAST MAY BE A TOUCH TOO COOL...BUT THE EXPECTED PERIOD OF BROKEN MID-LEVEL CLOUD COVER SHOULD HELP. HIGHS NEAR 50 NW TO MID/UPPER 50S SOUTHEAST. A SECONDARY ROUND OF LOW-LEVEL COLD ADVECTION WILL OCCUR WEDNESDAY EVENING/NIGHT IN ASSOCIATION WITH RENEWED LOW-LEVEL NWLY FLOW IN THE WAKE OF THE EXITING UPPER LEVEL TROUGH. MINS FOR THE SECOND CONSECUTIVE NIGHT WILL BE DRIVEN BY CAA. LOWS WED NIGHT IN THE UPPER 20S TO LOWER 30S. -CBL && .SHORT TERM /THURSDAY THROUGH FRIDAY/... AS OF 320 PM TUESDAY... A STRONG UPPER LEVEL TROUGH WILL STILL BE IN PLACE ALONG THE EASTERN US ON THURSDAY. THIS...ALONG WITH CONTINUED COLD AIR ADVECTION (NORTHWESTERLY WINDS OF 10-15 MPH WILL LEAD TO ANOTHER DAY OF BELOW NORMAL TEMPS. HIGHS ARE ONLY EXPECTED TO BE IN THE LOW 50S (POSSIBLY STRUGGLING TO EVEN REACH 50 DEGREES IN SOME LOCATIONS). THE UPPER LEVEL TROUGH AXIS WILL MOVE OFFSHORE THURSDAY NIGHT...BUT A DISTURBANCE WITHIN THE NORTHWEST FLOW ALOFT WILL MOVE SOUTHEASTWARD ACROSS THE REGION THURSDAY NIGHT INTO FRIDAY MORNING. IT STILL APPEARS THE MAIN IMPACT FROM THIS FEATURE WILL BE AN INCREASE IN MID LEVEL CLOUD COVER AS THE BOUNDARY LAYER IS PROGGED TO BE RATHER DRY. HOWEVER...CANNOT COMPLETELY SOME SPRINKLES OR A LIGHT SHOWER... ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. DESPITE CLOUD COVER...OVERNIGHT LOWS WILL GENERALLY BE WITHIN A DEGREE OR TWO OF FREEZING. CLOUDS WILL DECREASE THROUGHOUT THE DAY ON FRIDAY AS SUBSIDENCE INCREASES ON THE BACKSIDE OF THE DEPARTING SHORTWAVE. AS HEIGHTS INCREASE SOME...TEMPS WILL BEGIN TO MODERATE...WITH HIGHS IN THE MID/UPPER 50S AND OVERNIGHT LOWS IN THE MID/UPPER 30S EXPECTED. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 320 PM TUESDAY... UNCERTAINTY REMAINS HIGH DURING THE LONG TERM PERIOD. OVERALL...THE FLOW ALOFT IS PROGGED TO DEAMPLIFY AND TEMPS SHOULD GRADUALLY MODIFY THROUGH THE WEEKEND. MODELS ARE STILL INDICATING A BACKDOOR FRONT MOVING INTO THE AREA ON SATURDAY...BUT THERE IS CONSIDERABLE DISAGREEMENT ON HOW TO HANDLE THIS FRONT. THE LAST COUPLE OF RUNS OF THE GFS PUSH THE FRONT SOUTH OF THE AREA SATURDAY NIGHT...WHILE THE ECMWF STALLS THE FRONT SOMEWHERE NEAR THE FORECAST AREA. THIS CREATES A LOT OF DISAGREEMENT WITH RESPECT TO BOTH PRECIP CHANCES AND TEMPS. THEN MODELS SHOW A WAVE OF LOW PRESSURE DEVELOPING ON THE FRONT SUNDAY INTO MONDAY AND TRACKING EAST...ALTHOUGH WHERE EXACTLY THIS FRONT WILL BE (AND ASSOCIATED LOW TRACK) IS STILL IN QUESTION. MODELS ARE THEN IN GENERAL AGREEMENT WITH A MORE AMPLIFIED TROUGH ALOFT MOVING INTO THE MIDWEST ON TUESDAY...WITH AN ASSOCIATED SURFACE FRONT PROGGED TO CROSS THE REGION TUESDAY/TUESDAY NIGHT. GIVEN ALL THE UNCERTAINTY WILL NOT CHANGE THE FORECAST TOO MUCH...WITH SLIGHT CHANCE POPS OVER THE WEEKEND...BEFORE SLIGHTLY HIGHER POPS FOR EARLY NEXT WEEK. TEMPS ARE EXPECTED TO BE ABOVE NORMAL ON SATURDAY (AHEAD OF THE BACKDOOR FRONT)...WITH NEAR NORMAL TEMPS FOR THE REMAINDER OF THE PERIOD (ALTHOUGH IT WILL BE HIGHLY DEPENDENT ON FRONTAL POSITION). && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... AS OF 730 AM TUESDAY... CLEAR SKIES AND A STEADY 5-10KT NORTHWESTERLY WIND ARE EXPECTED OVERNIGHT BETWEEN A COLD FRONT MOVING OFFSHORE AND AN UPPER LEVEL DISTURBANCE APPROACHING FROM THE NORTHWEST. VFR CONDITIONS ARE EXPECTED TO CONTINUE ON WEDNESDAY AS THE UPPER DISTURBANCE CROSSES THE AREA...THOUGH STRONG WESTERLY WINDS WILL GUST TO NEAR 25KT DURING THE AFTERNOON. OUTLOOK... GUSTY NORTHWESTERLY WINDS ARE EXPECTED AGAIN ON THURSDAY...FOLLOWED BY A PASSING UPPER DISTURBANCE EARLY FRIDAY AND A VERY SMALL CHANCE OF A SHOWER. VFR CONDITIONS ARE EXPECTED TO PREVAIL. LATER IN THE WEEKEND...A COLD FRONT IS FORECAST TO SLIP SOUTH INTO CENTRAL NC AND LINGER THROUGH EARLY NEXT WEEK...BRING A CHANCE OF SUB-VFR CONDITIONS BY SUNDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GIH NEAR TERM...HARTFIELD/CBL SHORT TERM..KRR LONG TERM...KRR AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
358 PM EDT MON MAR 11 2013 .SYNOPSIS... A SLOW-MOVING COLD FRONT WILL APPROACH FROM THE WEST TONIGHT AND TUESDAY AND MOVE OFFSHORE TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST WEDNESDAY AND LINGER ACROSS THE AREA BEFORE MOVING OFFSHORE ON SATURDAY. ANOTHER COLD FRONT WILL APPROACH THE REGION SUNDAY AND MOVE OFFSHORE BY MONDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... AS OF 330 PM MONDAY...AFTER A VERY WARM AFTERNOON WITH HIGH TEMPERATURES AT OR ABOVE 70 DEGREES AT MANY LOCATIONS...CLOUDS WILL INCREASE OVERNIGHT AS LOW-LEVEL MOISTURE IS ADVECTED INTO THE REGION WITH A INCREASING SE SURFACE FLOW. THE CLOUDS AND WINDS SHOULD HOLD MINIMUM TEMPERATURES IN THE MILD MIDDLE AND UPPER 50S TONIGHT. THE 4KM WRF...ARW AND RAP MODELS KEEP MOST OF THE SIGNIFICANT PRECIPITATION WEST OF OUR CWA THROUGH ABOUT MIDNIGHT...ALTHOUGH A FEW LIGHT WARM ADVECTION LIGHT SHOWERS OR SPRINKLES MAY OCCUR LATER THIS EVENING. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... AS OF 330 PM MON...THERE IS STILL SOME CONCERN ON TUESDAY ABOUT A MINIMAL THREAT OF SEVERE WEATHER IN A WINDOW DURING THE MORNING AND EARLY AFTERNOON. STRONG LOW-LEVEL SSE/S WINDS ARE EXPECTED WITH GOOD LOW-LEVEL SHEAR VALUES AND THE AREA IN A RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET STREAK. LOW LEVEL (0-3 KM) HELICITY VALUES ARE FORECAST TO BE AS HIGH AS 300 M2/S2 DURING THE EARLY PART OF TUESDAY...HOWEVER CAPE VALUES LOOK TO MINIMAL WITH FORECAST LI`S OF ONLY ABOUT -1 PER FORECAST SOUNDINGS. THINK THE THREAT OF ANY THUNDER ENDS DURING THE MID-AFTERNOON AS THE COLD FRONT MOVES OFFSHORE IN THE EARLY EVENING. LOOKS LIKE MOST AREAS WILL RECEIVE ROUGHLY ONE HALF INCH OF RAIN TUESDAY. TEMPERATURES WILL RISE INTO THE MIDDLE 60S TO LOWER 70S FOR HIGHS ON TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... AS OF 300 PM MONDAY...MED RANGE MODELS IN DECENT AGREEMENT THROUGH FRIDAY...THEN DIVERGE FOR SAT-MON. INITIAL SHRT WV AND ASSCTD SFC FRONT WILL MOVE OFFSHORE TUE EVENING...FOLLOWED BY DRIER AND COLDER CONDITIONS FOR WED-THU NIGHT. UPPER FLOW THEN BECOMES MORE ZONAL FOR WEEKEND LEADING TO MODERATING TEMPS...BUT SOME MODEL DIFFERENCES ON HOW FAR SOUTH A EAST-WEST ORIENTED FRONT WILL PUSH SAT-MON. LEANED TO HPC SOLUTION WITH FRONT REMAINING JUST N OF AREA...BUT CONFIDENCE IS LOW. KEPT POPS TO JUST SLIGHT CHC FOR SAT NIGHT AND SUN WITH CHC ON MONDAY. UPR TROFFING WILL LEAD TO BELOW NORMAL TEMPS INTO FRIDAY...WITH THU THE COLDEST DAY WITH HIGHS ONLY NEAR 50 INLAND. TEMPS FCST TO MODERATE BACK INTO 60S SAT AND CONTINUE NEAR OR SLIGHTLY ABOVE NORMAL SUN-MON...BUT WILL BE DEPENDENT ON FRONTAL LOCATION. IF FRONT PUSHES THROUGH AND STALLS S OF AREA...TEMPS COULD BE 5-10 DEGS COOLER. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... SHORT TERM /THROUGH TUESDAY AFTERNOON /... AS OF 130 PM MON...VFR CONDITIONS WILL CONTINUE THROUGH MUCH OF THE EVENING AS A FRONT APPROACHES THE REGION TONIGHT. THE FRONT WILL SLOWLY CROSS THE AREA TOMORROW AFTERNOON WITH RAIN AHEAD OF ACTUAL BOUNDARY. AS MOIST SOUTHERLY FLOW INCREASES TONIGHT...ANTICIPATE SOME SHOWERS TO MOVE INLAND FROM OFF THE WATER AHEAD OF THE MAIN LINE OF PRECIPITATION. CEILINGS WILL BEGIN TO SLOWLY LOWER TONIGHT AND WILL EVENTUALLY BECOME MVFR BY EARLY TOMORROW MORNING. THE HEAVIER PRECIPITATION SHOULD CROSS THE TAF SITES BETWEEN 12Z-18Z. THEREFORE...ANTICIPATE CEILINGS TO DROP TO IFR CRITERIA...ALBEIT BRIEFLY. RAIN SHOULD TAPPER OFF BY TOMORROW LATE AFTERNOON. EXPECT ANY THUNDERSTORM ACTIVITY WILL OCCUR CLOSER TO THE COAST WITH BETTER INSTABILITY. CEILINGS WILL SCATTER OUT TOMORROW EVENING AS DRIER AIR ADVECTS ACROSS THE AREA. LONG TERM /TUE NIGHT THROUGH SATURDAY/... AS OF 300 PM MONDAY...VFR EXPECTED TO RETURN TUE NIGHT IN WAKE OF COLD FRONT MOVING OFF COAST...THEN PREVAILING THROUGH SAT WITH DRY HIGH PRES GRADUALLY BUILDING OVER AREA FROM NW. && .MARINE... SHORT TERM /TONIGHT AND TUESDAY/... AS OF 335 PM MONDAY...WINDS ARE PRETTY UNIFORM ON THE COASTAL WATERS AND SOUNDS THIS AFTERNOON WITH ESE/SE WINDS OF 10 TO 15 KNOTS. SEAS CONTINUE ROUGH...ESPECIALLY OVER THE NORTHERN WATERS WITH 7 TO 10 FEET WITH CONTINUED LONG PERIOD SWELLS. SEAS HAVE SUBSIDED SOMEWHAT ON THE SOUTHERN WATERS...BUT SHOULD INCREASE FROM THE SE/S TONIGHT AS GRADIENT IS PINCHED AS A COLD FRONT SLOWLY APPROACHES FROM THE WEST. GUSTY SOUTH WINDS OF 20 TO 25 KNOTS WITH A FEW GUSTS TO 30 KNOTS ARE EXPECTED ON TUESDAY IN ADVANCE OF THE FRONT WHICH SHOULD MOVE OFFSHORE DURING THE EARLY EVENING HOURS. NO CHANGES MADE TO CURRENT HEADLINES. LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 300 PM MONDAY...WIND SHIFT TO NW WILL FOLLOW FRONTAL PASSAGE TUE EVENING WITH INITIAL CAA SURGE GENERALLY LESS THAN 20 KT EARLY WED. STRONGER SURGE WITH GUSTS TO AROUND 25 KT WILL DEVELOP WED EVENING WITH PASSAGE OF MAIN UPR TROF AND CONTINUE INTO THU NIGHT. FLOW WILL THEN DIMINISH AND BACK TO W FRI AND FRI NIGHT AS HIGH PRES MOVES ACROSS TO S. LONG PERIOD SWELL FROM E-NE WILL GRADUALLY SUBSIDE DURING PERIOD...BUT MODERATE TO STRONG NW WINDS WITH CAA SURGE WILL PRODUCE SEAS TO AROUND 6 FT OVER OUTER PORTIONS INTO THU. SEAS FINALLY EXPECTED TO SUBSIDE BELOW 6 FT FRIDAY...BUT MAY BUILD TO 6 FT SRN PORTIONS LATE SAT WITH INCREASING SW WINDS. && .TIDES/COASTAL FLOODING... AS OF 340 PM MONDAY...HAVE EXTENDED THE HIGH SURF ADVISORY UNTIL 1 AM TONIGHT GIVEN CONTINUES LARGE SWELLS AND REPORTS OF ROADWAY ISSUES ALONG HIGHWAY 12 OVER THE OUTER BANKS. LARGE HIGH-ENERGY WAVES FROM A DEEP LOW PRESSURE SYSTEM OVER THE NORTHWESTERN ATLANTIC WILL CONTINUE TO BRING HIGH SURF CONDITIONS AND PERIODS OF OCEAN OVERWASH ACROSS THE OBX NORTH OF CAPE HATTERAS THROUGH THIS EVENING. SEAS ARE SLOWLY COMING DOWN BUT WILL STILL LIKELY HAVE BREAKERS OF 8 FT OR GREATER THIS EVENING. HIGHWAY 12 HAS BEEN IMPACTED BY SIGNIFICANT OVERWASH ESPECIALLY AT HIGH TIDE AND PORTIONS HAVE BEEN CLOSED AT TIMES NEAR MIRLO AND SHOULD CONTINUE INTO THIS EVENING. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...HIGH SURF ADVISORY UNTIL 1 AM EDT TUESDAY FOR NCZ103. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT FRIDAY FOR AMZ150-152-154. SMALL CRAFT ADVISORY UNTIL NOON EDT THURSDAY FOR AMZ156-158. && $$ SYNOPSIS...CTC NEAR TERM...CTC SHORT TERM...CTC LONG TERM...JBM AVIATION...LEP/JBM/CTC MARINE...JBM/CTC TIDES/COASTAL FLOODING...CTC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
203 AM EDT SUN MAR 10 2013 .SYNOPSIS... HIGH PRESSURE ALONG THE EAST COAST WILL DRIFT EASTWARD IN ADVANCE OF A COLD FRONT THAT WILL CROSS CENTRAL NC EARLY TUE. && .NEAR TERM /TONIGHT/... AS OF 915 PM SUNDAY... REST OF TONIGHT: BIGGEST CHALLENGE TONIGHT IS HOW MUCH STRATUS WILL FORM -- IF ANY -- AND WHERE IT WILL BE MOST WIDESPREAD. HIGH PRESSURE CENTERED JUST OFF THE MAINE COAST AND EXTENDING DOWN THE EASTERN SEABOARD ACCORDING TO THE LATEST SURFACE ANALYSIS WILL SLIP SLOWLY EASTWARD OFF THE COAST TONIGHT... RESULTING IN A SLOW BUT STEADY INFLUX OF ATLANTIC-SOURCE NEAR-SURFACE MOISTURE INTO NC AS WINDS SWING AROUND TO SOUTHEASTERLY. SURFACE DEW POINTS ACROSS CENTRAL NC HAVE VARIED WIDELY FOR THE LAST SEVERAL HOURS... FROM 15-20 EAST/CENTRAL TO 25-34 WEST LATE THIS AFTERNOON... AND THIS WIDE RANGE REMAINS ALBEIT WITH A MARKED INCREASE INTO THE 20S AND LOW 30S IN THE COASTAL PLAIN... PUSHING THE VALUES IN THE TEENS UP INTO THE NORTHEAST PIEDMONT. DEW POINTS IN THE UPPER 30S AND 40S ARE NOT FAR AWAY... RIGHT AT THE COAST AND JUST OFFSHORE... AND I SEE NOTHING TO SUGGEST THAT THIS HIGHER LOW-LEVEL MOISTURE WILL NOT CONTINUE TO SURGE INTO THE COASTAL PLAIN OVERNIGHT. THE LATEST RUNS OF THE RAP SUPPORT THIS ONSHORE SURGE OF MOISTURE... AS DO RECENT HRRR RUNS WHICH DEPICT RAPID DEVELOPMENT OF LOW CIGS ALONG AND EAST OF I-95 BEFORE 09Z. WORKING AGAINST SUCH A SCENARIO IS THE RESIDENT DRY AIR NOTED ON AREA SOUNDINGS... AS LOW LEVELS ARE MORE MOIST AT MHX/CHS THAN AT GSO BUT NOT INCREDIBLY SO. BUT GIVEN THE STABLE NEAR-SURFACE LAYER... THE AFTERNOON ABUNDANCE OF STRATOCU JUST OFF THE CAROLINA COAST... AND WITH A MULTITUDE OF MODELS (INCLUDING BUFR SOUNDINGS FROM THE NAM AND GFS) SHOWING LOW STRATUS FORMING BY MORNING ESPECIALLY IN THE EAST... WILL INCREASE SKY COVER ESPECIALLY IN THE EASTERN HALF OF THE CWA. MOISTURE REMAINS ELEVATED IN THE WESTERN PIEDMONT AS WELL... AND UPSLOPE FLOW MAY RESULT IN AREAS OF STRATUS HERE AS WELL... ALTHOUGH TRAJECTORIES SUGGEST THAT THE ISOLATED POCKET OF DRY SURFACE AIR NOW FOUND OVER INTERIOR SOUTHEAST NC AND NORTHEAST SC WILL TRANSLATE INTO THIS AREA... LIMITING STRATUS FORMATION SOMEWHAT. TEMPS HAVE ALREADY DROPPED INTO THE 40S IN ISOLATED SPOTS BUT 50S REMAIN WIDESPREAD ENOUGH TO JUSTIFY A SLIGHT UPWARD TICK IN LOWS TONIGHT... GIVEN THE ANTICIPATED CLOUD DEVELOPMENT. LOWS 39-46. -GIH && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 225 PM SUNDAY... LEADING EDGE OF A 45-50KT SOUTHERLY LOW-LEVEL JET EMBEDDED IN THE BROAD WARM AIR CONVEYOR BELT DOWNSTREAM OF THE SYSTEM WILL BEGIN TO ADVECT GULF MOISTURE NORTHWARD LATE MONDAY AFTERNOON...WHICH WILL RESULT IN SCATTERED SHOWERS BREAKING OUT OVER THE AREA LATE MONDAY AFTERNOON/EARLY EVENING. DEEP LAYER FORCING VIA DIFFLUENT FLOW ALOFT ASSOCIATED WITH A COUPLED JET STRUCTURE ATOP STRONG LOW-LEVEL MOISTURE FLUX CONVERGENCE ALONG THE SOUTHERLY LOW-LEVEL JET WILL ARRIVE FROM THE WEST AOA MIDNIGHT MONDAY NIGHT WITH SIGNIFICANT-WIDESPREAD(CATEGORICAL)CONVECTIVE SHOWERS SPREADING WEST TO EAST THROUGH THE AREA THROUGH 15Z TUESDAY MORNING BEFORE THIS SUPPORT MOVES OFFSHORE. THE LOW-LEVEL JET AND ATTENDANT LINE OF CONVECTION WILL SERVE AS THE EFFECTIVE FRONT WITH ONLY AN ISOLATED SHOWER EXPECTED WITH THE ACTUAL TRAILING SFC COLD FRONT AS IT MOVES THROUGH THE AREA BETWEEN 15 TO 21Z TUESDAY. A SOLID ONE QUARTER TO ONE HALF INCH OF RAINFALL LOOKS TO BE IN ORDER FOR ALL OF CENTRAL NC. THUNDER/SEVERE THREAT: WITH THE STRONG TROUGH DYNAMICS AND LOW-LEVEL KINEMATIC FIELDS TRAVERSING THE CAROLINAS BETWEEN 06 TO 15Z TUESDAY... WEAK TO MODEST MID-LEVEL LAPSE RATES OF 5.5 TO 6.0 C/KM--NOCTURNAL BOUNDARY LAYER COOLING OVERNIGHT ALONG WITH RATHER WIDESPREAD LOW-LEVEL CLOUD COVER ACROSS THE AREA THROUGH MIDDAY TUESDAY WILL RESULT IN MEASLY INSTABILITY (100-200 J/KG MUCAPE)ACROSS EASTERN NC. SO WHILE NOT ZERO...BOTH THUNDER AND A SEVERE THREAT ARE VERY LOW. WILL NOT INCLUDE A MENTION OF THUNDER AT THIS TIME. TEMPERATURES: MILD OVERNIGHT LOWS MONDAY NIGHT GIVEN WIDESPREAD RAIN AND CLOUDS. LOWS IN THE LOWER 50S NW TO MID-UPPER 50S SOUTHEAST. NOT MUCH DIFFERENCE IN HIGHS TEMPERATURES FROM MONDAY TO TUESDAY WITH CAA DELAYED UNTIL TUESDAY NIGHT. AS SUCH...CLOUD COVER WILL BE THE MAIN DETERMINING FACTOR. HIGHS BOTH DAYS IN THE LOWER 60S NW TO NEAR 70 SOUTHEAST. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... AS OF 225 PM SUNDAY... TO START THE LONG TERM PERIOD...THE COLD FRONT AND ASSOCIATED PRECIP ARE EXPECTED TO BE EAST OF THE AREA BY EARLY TUESDAY EVENING...WITH ANY LINGERING CLOUDS ACROSS THE EASTERN PORTIONS OF THE FORECAST AREA CLEARING SHORTLY AFTER. COLD AIR ADVECTION BEHIND THE DEPARTING FRONT WILL LEAD TO COOLER OVERNIGHT LOWS...GENERALLY IN THE MID TO UPPER 30S. THEN...MUCH OF THE PERIOD IS EXPECTED TO BE DOMINATED BY A BROAD UPPER TROUGH. THIS WILL RESULT IN BELOW NORMAL TEMPS... ESPECIALLY WED AND THU AS SOME COLD AIR ADVECTION CONTINUES. TEMPS SHOULD REBOUND SLIGHTLY TO NEAR NORMAL BY THE END OF THE WEEK AND INTO THE WEEKEND AS HEIGHTS RISE SOME. WITH REGARDS TO ANY PRECIP... WITH NORTHWESTERLY FLOW ALOFT PERSISTING ACROSS OUR REGION...MODELS CONTINUE TO PROG SEVERAL DISTURBANCES/CLIPPERS MOVING SOUTHEAST WITHIN THIS FLOW. HOWEVER...UNCERTAINTY REMAINS HIGH WITH RESPECT TO EXACT TRACK OF THESE (AND TIMING IN GENERAL) AND WITH MOISTURE REMAINING RATHER LIMITED...WILL MAINTAIN A DRY FORECAST THROUGH AT LEAST THE END OF THE WEEK. UNCERTAINTY INCREASES EVEN MORE BY THE WEEKEND AS MODELS ARE SHOWING A BACKDOOR FRONT IMPACTING THE AREA (TO VARYING DEGREES). MOISTURE IS PROGGED TO BEGIN TO INCREASE DURING THIS TIME FRAME AS WELL AND THEREFORE WILL GO AHEAD AND INTRODUCE SLIGHT CHANCE POPS FOR THE WEEKEND...ALTHOUGH CONFIDENCE IS FAIRLY LOW. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 201 AM MONDAY... 24-HR TAF PERIOD: HIGH CLOUDS INCREASING AHEAD OF THE COLD FRONT APPROACHING THE AREA... INDICATIONS ARE THAT INCREASING SOUTHERLY FLOW AND MOISTURE WILL RESULT IN THE FORMATION OF LOW STRATUS IN THE EARLY MORNING OVER THE AREA... AND DEWPOINTS ACROSS THE COASTAL PLAIN AND PIEDMONT HAVE RISEN OVER THE PAST FEW HOURS TO THE MID AND UPPER 20S. CLOUDY CONDITIONS WILL CONTINUE THROUGH THE DAY...WITH CIGS RISING IN THE MORNING HOURS TO MVFR AFTER 12Z. RAIN CHANCES WILL INCREASE LATE IN THE 24 HOUR PERIOD... AFFECTING INT AND GSO FIRST BEFORE MOVING EAST. LOOKING AHEAD: RAIN WILL BE EXITING THE REGION AFTER 18Z TUESDAY... BRINGING A RETURN TO VFR CONDITIONS. WINDS GUSTING 15 TO 20KTS WILL BE POSSIBLE DURING THE AFTERNOON HOURS ON TUESDAY AND WEDNESDAY. VFR CONDITIONS REMAIN LIKELY THROUGH THE REST OF THE WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...HARTFIELD SHORT TERM..CBL LONG TERM...KRR AVIATION...SEC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
328 PM CDT MON MAR 11 2013 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT... MAIN HIGHLIGHT IN THE SHORT TERM IS A WINTER WEATHER ADVISORY ACROSS THE NORTH...AND THE JAMES RIVER VALLEY MONDAY NIGHT THROUGH EARLY TUESDAY MORNING. THE LATEST SURFACE MAP SHOWS A STRONG COLD FRONT STRETCHING FROM NEAR LAKE WINNIPEG SOUTHWEST INTO REGINA. A RATHER LARGE AREA OF 3HR MAX PRESSURE RISES OF 4MB WAS CENTERED OVER SOUTH CENTRAL SASKATCHEWAN. NORTHWEST WINDS OF 25 TO 35 MPH ASSOCIATED WITH THIS WERE OCCURRING OVER SEVERAL LOCATIONS...WITH VISIBILITIES RANGING ANYWHERE FROM 3/4 OF A MILE TO 8 MILES. WITH RECENT SNOWFALL IN THE NORTH AND THE JAMES RIVER VALLEY...IN COMBINATION WITH THE GUSTY WINDS TO 35 MPH TONIGHT...SIGNIFICANT BLOWING AND DRIFTING SNOW WILL CAUSE VISIBILITIES OF A MILE OR LESS AND HAZARDOUS TRAVEL. THE LATEST RAP MODEL DRAGS THE CENTER OF THE PRESSURE RISE AREA INTO NORTHERN NORTH DAKOTA BY 06Z AND INTO THE JAMES RIVER VALLEY AT 12Z. SCATTERED SNOW SHOWERS WILL ACCOMPANY THE COLD FRONT WITH ACCUMULATIONS OF AROUND ONE INCH. THIS WILL FURTHER ADD TO THE REDUCTION IN VISIBILITIES AND HAZARDOUS TRAVEL OVERNIGHT AND EARLY TUESDAY MORNING. DESPITE LARGE SCALE ASCENT ABSENT FROM THIS SYSTEM...MOST OF THE SNOW SHOWERS WILL BE DRIVEN BY LOW LEVEL INSTABILITY. DECENT LOW LEVEL LAPSE RATES ARE ACHIEVED AS THE COLD H85 POCKET OF -12C TO -14C SLIDES INTO WESTERN AND CENTRAL NORTH DAKOTA TONIGHT. AS MENTIONED ABOVE...SNOWFALL ACCUMULATIONS OF AROUND ONE INCH POSSIBLE WITH THESE SNOW SHOWERS. FOR TUESDAY...SCATTERED SNOW SHOWERS AND GUSTY WINDS LINGER IN THE JAMES RIVER VALLEY DURING THE MORNING. OTHERWISE A COLDER DAY WITH A 1032MB SURFACE HIGH PRESSURE ARRIVING IN NORTHWEST NORTH DAKOTA BY 18Z WITH LIGHTER WINDS AND MORE SUNSHINE DEVELOPING FROM WEST TO EAST. HIGHS TUESDAY WILL RANGE FROM 20 NORTH TO LOWER 30S SOUTHWEST. FOR TUESDAY NIGHT..WARM AIR ADVECTION ARRIVES IN THE WEST WITH UPGLIDE/ASCENT ADVERTISED ON THE 285-295K PRESSURE SURFACES. THUS HAVE SLIGHT CHANCE OF SNOW TUESDAY EVENING IN THE WEST FOLLOWED BY A CHANCE AFTER MIDNIGHT. SNOWFALL AMOUNTS OF AROUND ONE HALF INCH POSSIBLE TUESDAY NIGHT IN THE WEST. .LONG TERM...WEDNESDAY THROUGH MONDAY NIGHT... HIGHLIGHTS OF THE EXTENDED FORECAST ARE ABOVE AVERAGE TEMPERATURES TO BEGIN THE PERIOD...WITH TEMPERATURES TRENDING POTENTIALLY BELOW NORMAL LATE NEXT WEEK AND INTO THE WEEKEND. WIDESPREAD ACCUMULATING SNOW IS ALSO POSSIBLE THURSDAY NIGHT INTO FRIDAY. A WARM FRONT IS FORECAST TO PROPAGATE ACROSS WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE DAY ON WEDNESDAY. A RATHER LARGE TEMPERATURE GRADIENT IS EXPECTED WITH HIGHS IN THE 20S AND LOWER 30S OVER THE SNOWPACK AHEAD OF THE WARM FRONT...TO THE UPPER 50S ACROSS THE SOUTHWEST WITH BARE GROUND. THE 12 UTC GFS BECOMES A CLEAR OUTLIER FRIDAY ONWARDS AS IT IS THE DEEPEST AND FASTEST SOLUTION IN REGARDS TO A SURFACE LOW ACROSS NORTHERN MONTANA THURSDAY NIGHT...PROPAGATING INTO MINNESOTA ON FRIDAY. THUS...FOLLOWED THE 12 UTC ECMWF/GEM WHICH BUILD ARCTIC HIGH PRESSURE INTO NORTH DAKOTA FRIDAY THROUGH THE WEEKEND. THESE MODELS ALSO HAVE SHOWN GOOD TEMPERATURE VERIFICATION WITH BIAS CORRECTION APPLIED TO ACCOUNT FOR THE FAIRLY CONSISTENT SNOW/SNOW FREE AREAS. THUS...ANOTHER LARGE TEMPERATURE GRADIENT IS POSSIBLE THURSDAY WITH HIGHS IN THE 20S NORTH TO THE LOWER 60S SOUTHWEST...WITH HIGHS 10 TO 20 DEGREES COOLER FOR SATURDAY AS THE ARCTIC HIGH BUILDS IN. IN REGARDS TO PRECIPITATION...WIDESPREAD ACCUMULATING SNOW IS POSSIBLE THURSDAY NIGHT INTO FRIDAY WITH FRONTOGENESIS ASSOCIATED WITH THE BAROCLINIC ZONE ON THE LEADING EDGE OF THE AFOREMENTIONED SURFACE HIGH. && .AVIATION...AS OF 2030 UTC...A WEAK FRONT WAS ENTERING EASTERN NORTH DAKOTA. STRONG NORTHWEST WINDS WITH GUSTS OF 25-30 KTS WERE OCCURRING BEHIND THIS FRONT IN WESTERN AND CENTRAL NORTH DAKOTA. A SECOND...AND STRONGER COLD FRONT LOCATED ACROSS SOUTHEAST SASKATCHEWAN WILL DROP SOUTH INTO NORTH DAKOTA LATE THIS AFTERNOON AND THROUGH THE EVENING. EVEN STRONGER GUSTS OF 30-40 KTS ARE EXPECTED BEHIND THIS FRONT WITH SCATTERED SNOW SHOWERS. BLOWING SNOW IS ALSO A CONCERN AT KISN...KMOT AND KJMS THIS EVENING AND TONIGHT...WITH IFR VISIBILITIES WHEN COMBINED WITH SNOW SHOWERS POSSIBLE. OTHERWISE...MVFR CEILINGS ARE EXPECTED BEHIND THE SECOND FRONT AS STRATUS OVERSPREADS THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 1 AM TO 10 AM CDT TUESDAY FOR NDZ021>023-025-036-037-047-048-050-051. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM CDT TUESDAY FOR NDZ001>005-009>013. && $$ SHORT TERM...KS LONG TERM/AVIATION...AYD
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
656 AM EDT MON MAR 11 2013 .SYNOPSIS... MOIST SOUTHERLY FLOW AHEAD OF A COLD FRONT WILL BRING WIDESPREAD SHOWERS TO THE REGION TODAY. THE COLD FRONT WILL PUSH EAST TONIGHT WHICH WILL SIGNAL THE END OF WIDESPREAD PRECIPITATION. A COLD UPPER LEVEL TROUGH WILL DIG SOUTHEAST INTO THE GREAT LAKES AND OHIO VALLEY TUESDAY INTO WEDNESDAY. THIS PATTERN WILL BRING A THREAT OF RAIN AND SNOW SHOWERS ALONG WITH BELOW NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NWP MODELS WERE IN FAIRLY DECENT AGREEMENT IN TERMS OF SYNOPTIC SCALE FORCING AND TIMING OF FEATURES. HAVE USED A BLEND OF THE NAM...GFS AND THE RAP FOR THE NEAR TERM FORECAST. PRECIPITATION ACROSS THE REGION TODAY WILL COME IN TWO SEPARATE WAVES. THE FIRST BOUT OF SHOWERS WILL ACCOMPANY A MOIST...LOW LEVEL JET WHICH WILL PUSH SOUTHWEST TO NORTHEAST THROUGH THE MORNING AND EARLY AFTERNOON HOURS. AS THIS SHIFTS EAST...AN UPR LVL S/WV AND ACCOMPANYING SFC COLD FRONT WILL SWING THROUGH THE WESTERN ZONES THIS AFTERNOON...PUSHING THROUGH THE EASTERN ZONES BY EARLY EVENING. THIS FEATURE WILL ALSO BRING ANOTHER ROUND OF SHOWERS. RAINFALL WITH THE FIRST WAVE IS EXPECTED TO BE THE HEAVIEST WITH 0,50 TO 1.25 INCHES OF RAIN EXPECTED. THERE CONTINUES TO BE SOME CONCERN FOR FLOODING GIVEN THE RECENT SNOW MELT AND MOIST TO NEARLY SATURATED GROUND...PARTICULARLY IN THE WHITEWATER...MIAMI...AND UPPER SCIOTO RIVER BASINS. ATTM...BELIEVE WIDESPREAD FLOODING IS NOT EXPECTED GIVEN STEADY BUT PROGRESSIVE MOVEMENT TO THE EAST OF THE FIRST BATCH OF SHOWERS. HOWEVER...WILL CONTINUE TO MONITOR FOR ANY POTENTIAL FLOOD ADVISORIES GIVEN HIGH STREAM LEVELS PER USGS WEB SITE AND SATURATED SOILS. WILL ALSO HIGHLIGHT THIS THREAT IN THE HWO PRODUCT. WILL ALSO MONITOR THE LINE OF SHOWERS EXPECTED WITH FRONTAL PASSAGE AS SOME MODELS INDICATE THAT SOME GUSTY WINDS MAY OCCUR. AS FOR TEMPERATURES...THEY WILL BE TRICKY GIVEN PERSISTENT RAIN ACRS THE WEST BUT LATE ARRIVING IN THE FAR EAST. HAVE HIGHS RANGING FROM THE LOWER 50S WEST TO THE UPPER 50S FAR EAST. HOWEVER...IF RAIN IS SLOWER TO ARRIVE IN THE FAR EAST...TEMPERATURES MAY WARM INTO THE 60S. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... AFOREMENTIONED COLD FRONT AND S/WV WILL MOVE OFF TO THE EAST THIS EVENING WHICH WILL SIGNAL THE END OF WIDESPREAD PCPN. TEMPERATURES WILL FALL OVERNIGHT IN THE CAA PATTERN BEHIND THE FRONT. MODELS CONTINUE TO SUGGEST THAT AN EMBEDDED DISTURBANCE WILL APPROACH THE AREA FROM THE WEST LATE. THIS MAY TRIGGER A FEW SNOW SHOWERS ACRS THE NRN ZONES BY MORNING. FOR THE PERIOD TUESDAY INTO WEDNESDAY...A COLD UPR LEVEL TROUGH IS FORECAST TO DIG SOUTHEAST INTO THE GREAT LAKES AND OHIO VALLEY. SKIES ON TUESDAY WILL BE MOSTLY CLOUDY WITH PERHAPS A FEW LIGHT RAIN AND SNOW SHOWERS ACROSS THE NORTH IN THE CAA PATTERN WHICH WILL BRING SOME LOW LEVEL INSTABILITY. AN EMBEDDED S/WV ROTATING AROUND THE LOW IS EXPECTED TO PASS ACRS THE REGION TUESDAY NIGHT. THIS FEATURE WILL BRING A CHANCE OF SNOW SHOWERS AND HAVE RAISED POPS UP INTO THE 40 PERCENT RANGE. ON WEDNESDAY...CAA WILL BE IN FULL SWING AS LOW LEVEL MOIST...COLD CYCLONIC FLOW ACROSS THE GREAT LAKES COMBINED WITH SOME DAYTIME HEATING WILL RESULT IN A CHANCE OF SNOW SHOWERS...BEST FAVORED FROM LATE MORNING INTO THE MID AFTERNOON HOURS. MODEL SOUNDINGS DEPICT STEEP LOW LEVEL LAPSE RATES ALONG WITH THE LOW LEVEL MOISTURE INTERSECTING THE DENDRITIC GROWTH ZONE. THE MAJORITY OF OPERATIONAL MODELS USED THIS FAR OUT OUR NOT CONVECTIVE ALLOWING...AND AS A RESULT...MAY BE UNDER DOING THE CONVECTIVE ACTIVITY AS HAS BEEN THE CASE THIS PAST WINTER. HAVE RAISED POPS TO 40 PERCENT...BUT WOULD NOT BE SURPRISED IF THE ACTIVITY ENDS UP BEING IN THE LIKELY CATEGORY. COLD UPR LEVEL TROUGH WILL MOVE EAST WEDNESDAY NIGHT. THIS SHOULD ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE REGION LATE. CLOUDS WILL DECREASE AND WITH THE LOSS OF DAYTIME HEATING...SNOW SHOWERS SHOULD WANE FROM WEST TO EAST. AS FOR TEMPERATES...HIGHS ON TUESDAY WILL RANGE FROM THE UPPER 30S NORTH TO THE MID 40S SOUTH. HIGHS ON WEDNESDAY WILL STRUGGLE TO WARM INTO THE MID AND UPPER 30S. && .LONG TERM /THURSDAY THROUGH SUNDAY/... SURFACE HIGH PRESSURE WILL PUSH ACROSS THE AREA THURSDAY INTO FRIDAY. THIS WILL PROVIDE FOR MAINLY DRY CONDITIONS ALONG WITH A GRADUAL WARM UP EACH DAY. IN A NORTHWEST FLOW PATTERN ALOFT...SHORT WAVE ENERGY WILL DROP DOWN INTO THE AREA FRIDAY INTO SATURDAY. HOWEVER...THERE ARE SOME TIMING/STRENGTH AND PLACEMENT ISSUES BETWEEN THE 12Z GFS/CMC AND 00Z ECMWF WITH THE GFS THE FASTEST AND THE ECMWF THE SLOWEST. THE OVERALL TREND HAS BEEN SLOWER SO WILL TRIM BACK POPS HEADING INTO FRIDAY AFTERNOON AND THEN INCREASE THEM FOR FRIDAY NIGHT INTO SATURDAY. BOTH THE GFS AND ECMWF LOOK LIKE THEY ARE TRYING TO LAY OUT A BOUNDARY SOMEWHERE ACROSS THE OHIO OR TENNESSEE VALLEY LATE IN THE WEEKEND. THIS WILL LIKELY LINGER PCPN ON INTO SUNDAY...ESPECIALLY ACROSS OUR SOUTHERN AREAS. PTYPE THROUGH THE LATER PART OF THE LONG TERM SHOULD GENERALLY BE RAIN...ALTHOUGH LOW LEVELS COULD COOL OFF ENOUGH TO SEE THE POSSIBILITY OF SOME SNOW MIXING IN ACROSS THE NORTH. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY BELOW NORMAL THROUGH THE WEEKEND. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... A COLD FRONT IS SLOWLY APPROACHING THE REGION...AND A STEADY STREAM OF RAIN WILL CONTINUE TO MOVE NORTHEAST THROUGH THE REGION TODAY. WHILE CLOUDS OVER THE AREA ARE STILL GENERALLY IN THE 4000-6000 FOOT RANGE...SIGNIFICANTLY LOWER CLOUDS ARE LOCATED UPSTREAM IN PARTS OF INDIANA AND KENTUCKY. TEMPO GROUPS HAVE BEEN INCLUDED FOR ALL THE TAF SITES TO ATTEMPT TO TIME OUT THESE LOWER CEILINGS...WHICH ARE EXPECTED TO BE IN THE 1000-1500 FOOT RANGE. IFR CEILINGS ARE NOT OUT OF THE QUESTION...BUT IT LOOKS LIKE THIS WILL BE MORE LIKELY NORTH AND WEST OF THE TAF SITES. AS THE RAIN CONTINUES...OCCASIONAL MVFR VISIBILITIES ARE EXPECTED. BY AFTERNOON...THE FRONTAL PASSAGE WILL PROMPT A QUICK CHANGE IN WIND DIRECTION FROM THE SOUTH TO THE WEST-SOUTHWEST. WIND GUSTS AHEAD OF...DURING...AND JUST AFTER THE FRONTAL PASSAGE MAY REACH AS HIGH AS THE 25-30 KNOT RANGE. THE VAST MAJORITY OF THE PRECIPITATION IS AHEAD OF THE FRONT...BUT SOME LIGHT SHOWERS ARE EXPECTED BEHIND IT. THOUGH THERE MAY BE SOME BRIEF CLEARING IN THE CLOUD DECKS (ESPECIALLY JUST AFTER THE FRONT PASSES)...MVFR CEILINGS ARE EXPECTED TO BE THE PREVAILING CONDITION. THESE CLOUDS SHOULD PERSIST (AND EVEN LOWER A BIT) GOING INTO THE OVERNIGHT PERIOD AND EARLY TUESDAY MORNING. OUTLOOK...MVFR CEILINGS WILL BE POSSIBLE THROUGH TUESDAY MORNING. MVFR CEILINGS ARE AGAIN EXPECTED ON TUESDAY NIGHT INTO WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...JGL AVIATION...HATZOS
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1054 PM CDT TUE MAR 12 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 342 PM CDT TUE MAR 12 2013 TEMPERATURES AND TRENDS TONIGHT WILL BE VERY DEPENDENT ON A DIFFICULT CLOUD FORECAST. A LARGE PART OF CURRENT CLOUD COVERAGE IS DIURNALLY SUPPORTED AS BREAKS HAVE FILLED BACK IN DURING THE DAY...WITH SCATTERED COVERAGE OF VERY LIGHT SNOW OR FLURRIES OVER MUCH OF THE CWA. RAP SOMEWHAT A JECKYLL AND HYDE OF LATE WHEN IT COMES TO LOWER CLOUD PREDICTION...BUT GENERALLY SEEMS ON TRACK WITH CURRENT CLOUDS. HAS A MUCH SLOWER CLEARING RATE FROM WEST TO EAST...BUT PROBABLY TOO MUCH SO WITH THE DEGREE OF DIURNALLY DRIVEN CLOUDS WHICH WILL ERODE QUICKLY WEST...AND TO SOME DEGREE IN THE FAR EAST AS WELL...LEAVING A MORE PERSISTENT BAND DOWN THE MIDDLE TO DISSIPATE MORE SLOWLY AND BUILD EAST. COMPLICATING TRENDS WILL BE THE SLOW EASTWARD SHIFT IN SURFACE RIDGE...BRINGING LIGHT RETURN FLOW TO AREAS FROM THE JAMES VALLEY WEST LATER NIGHT...ALONG WITH INCREASING HIGH LEVEL CLOUDS. COULD BE A FEW LOCATIONS OF BLOWING SNOW THROUGH LATE AFTERNOON IN DEEPER SNOW AREAS NORTH AND EAST...BUT OVERALL TREND IN WINDS GOING INTO THE EVENING WILL BE DOWN...AND EXPECT WILL NOT CONTINUE INTO THE EVENING. MUCH OF CURRENT PRECIPITATION RESULT OF THE STEEP LOW LEVEL LAPSE RATES...AND WILL PROBABLY TAKE A COUPLE OF HOURS INTO THE EVENING BEFORE FULLY LOSING A FLURRY THREAT WITH TEMPS IN CLOUD LAYER SUPPORTIVE OF ICE PROCESS. ON WEDNESDAY...DECENT COVERAGE OF MID/HIGH CLOUDS WILL PUSH EASTWARD ACROSS THE AREA. WEAKER LOW LEVEL GRADIENT AND SNOWCOVER EAST WILL RESTRAIN TEMPERATURES TO THE LOWER PORTIONS OF GUIDANCE RANGE WITH UPPER 20S. MUCH WARMER AIRMASS PUSHES INTO THE WEST...SHOULD ALLOW SOME LOWER 40S. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 342 PM CDT TUE MAR 12 2013 BOTH THURSDAY AND FRIDAY PLACE THE CWA RIGHT ALONG A STRONG THERMAL GRADIENT IN THE LOW LEVELS WHICH MAKES FORECASTING HIGHS TRICKY. NOT JUST SIMPLY DUE TO THE STRONG THERMAL GRADIENT BUT IF THURSDAY DOES NOT PROVIDE ENOUGH SOLAR RADIATION THE SNOW MAY NOT MELT AS MUCH AS EXPECTED WHICH COULD INFLUENCE HIGHS ON THURSDAY. WILL PLAN ON SOME MELTING TO OCCUR WEDNESDAY IN CENTRAL SOUTH DAKOTA WHICH WILL ALLOW TEMPERATURES TO CLIMB A BIT SOUTH OF INTERSTATE 90 WHERE MUCH OF THAT AREA IS ALREADY SNOW FREE...ON THE SOUTH DAKOTA SIDE OF THINGS. SO WILL GO CLOSE TO 60 IN THESE LOCATIONS TAPERING OFF TO NEAR 40 IN SOUTHWEST MINNESOTA. BUT AGAIN...WITH THE TIGHT THERMAL GRADIENT CONFIDENCE IS NOT EXTREMELY HIGH. THIS THERMAL GRADIENT SHIFTS A BIT NORTHWARD ON THURSDAY NIGHT INTO FRIDAY BEFORE SLIDING BACK SOUTHWARD AS A WAVE MOVES THROUGH NORTH DAKOTA WHICH WILL PUSH THIS COLDER AIR SOUTH. WILL KEEP TEMPERATURES MILD THURSDAY NIGHT...WITH LOWS IN UPPER 20S TO LOWER 30S. WILL RULE OUT THE GFS AND LEAN TOWARDS THE EC AND NAM OUTPUT ON FRIDAY. THE GFS DOES NOT SEEM TO HANDLE LOW LEVEL FEATURES OF SYSTEMS TO THE NORTH VERY WELL AS IT TENDS TO COLLAPSE THE COLD AIR INTO THE PRE FRONTAL TROUGH WHILE THE EC AND NAM TEND TO HANDLE THIS BETTER. WHAT THIS MEANS IS THAT FRIDAY SHOULD BE VERY MILD ...ESPECIALLY DOWN THE MISSOURI RIVER WHICH WILL AGAIN SEE TEMPERATURES CLIMB TO AROUND 60 WHILE 40 TO 45 SHOULD BE MORE COMMON IN THE NORTH. IN FACT IF THINGS ARE AS SLOW AS THE NAM SUGGESTS IT COULD CLIMB INTO THE LOWER 50S ALONG THE HIGHWAY 14 CORRIDOR. SATURDAY AND SUNDAY WILL SEE FAIRLY STRONG WEST/NORTHWEST FLOW ALOFT AHEAD OF A MARGINALLY AGREED UPON FORECAST TROUGH OF LOW PRESSURE FOR SUNDAY NIGHT INTO MONDAY NIGHT. WITH COLD AIR IN PLACE ON SATURDAY MORNING WEAK EAST TO SOUTHEAST FLOW WILL TRY TO RETURN CONDITIONS BACK TO NORMAL BUT COLDER AIR WILL BEGIN TO SINK SOUTH SUNDAY AHEAD OF THE TROUGH OF LOW PRESSURE. OVERALL EACH OF THE MODELS IS COLD ENOUGH THAT ANY PRECIPITATION THAT FALLS WOULD BE SNOW WITH AN EAST TO SOUTHEAST LOW LEVEL FLOW ADVECTING IN THE COOLER AND DRIER AIR TO THE EAST. COLDER AIR BURIES IN BEHIND THIS WAVE TUESDAY INTO WEDNESDAY BUT AGAIN...SOME DECENT TIMING DIFFERENCES SO CONFIDENCE IS AVERAGE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1050 PM CDT TUE MAR 12 2013 MOST OF THE CWA SHOULD REMAIN VFR THROUGH TONIGHT. SOME MVFR STRATUS IS LINGERING ACROSS PORTIONS OF OUR EAST...BUT EXPECT MOST OF THIS TO CONTINUE TO DISSIPATE OVER THE NEXT FEW HOURS. WINDS WILL ALSO CONTINUE TO DIMINISH AND THEN TURN SOUTH SOUTHEASTERLY TOMORROW...GENERALLY AT 12 KTS OR LESS. ONLY EXPECTING SOME INCREASING MID AND HIGH CLOUDS TOMORROW...WITH VFR CONDITIONS CONTINUING. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...CHAPMAN LONG TERM...08 AVIATION...CHENARD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
928 AM CDT MON MAR 11 2013 .SHORT TERM... 928 AM CDT MON MAR 11 2013 GIVEN CURRENT RADAR TREND WITH LINGERING STRETCHED DEFORMATION BAND/STRONG 700-600MB FRONTOGENETIC FORCING...HAVE OPTED TO EXTEND THE CURRENT WINTER STORM WARNING/WINTER WEATHER ADVISORY TIL NOON TODAY. ALSO WITH TIGHTENING BAND OF SNOW...TRIMMED OFF DODGE COUNTY IN MN FROM THE WINTER STORM WARNING AND MONROE COUNTY IN WISCONSIN FROM THE WINTER WEATHER ADVISORY. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY 346 AM CDT MON MAR 11 2013 A FAIRLY ACTIVE NORTHWEST FLOW REMAINS ACROSS THE AREA THROUGH THIS TIME PERIOD. SHORT WAVES WILL BRING CHANCES OF PRECIPITATION ON THURSDAY...FRIDAY AND FRIDAY NIGHT...AND SUNDAY AND SUNDAY NIGHT. THE PRECIPITATION TYPES DURING THIS TIME FRAME IS HIGHLY DEPENDENT ON WHERE THE BAROCLINIC ZONE SETS UP. THEREFORE JUST WENT WITH A MIX OF RAIN AND SNOW FOR THESE TIME PERIODS. && .AVIATION...TODAY AND TONIGHT 627 AM CDT MON MAR 11 2013 AN ELONGATED AREA OF LOW PRESSURE WAS LOCATED FROM NORTHERN ILLINOIS INTO EASTERN WISCONSIN. DEFORMATION BAND OF SNOW WAS LOCATED OVER NORTHEAST IOWA INTO SOUTHEAST MINNESOTA...AFFECTING THE KRST TAF SITE WITH 1 1/2SM VISIBILITY IN SNOW. 11.08Z HRRR SHOWS THIS BAND TO TRANSLATE EASTWARD THIS MORNING AS THE LOW PULLS AWAY. THUS EXPECT VISIBILITIES TO DROP AT KLSE BETWEEN 14Z-17Z INTO THE 1-3SM RANGE. EXPECT CEILINGS TO REMAIN IFR AT KRST UNTIL 17Z THEN RISE INTO THE MVFR CATEGORY. AT KLSE...CEILINGS WILL REMAIN IN THE MVFR CATEGORY. THE SNOW WILL TAPER OFF EARLY THIS AFTERNOON...BUT THE MVFR CEILINGS WILL CONTINUE THROUGH THE REMAINDER OF THE TAF PERIOD. && .ARX WATCHES/WARNINGS/ADVISORIES... 928 AM CDT MON MAR 11 2013 WI...WINTER STORM WARNING UNTIL NOON CDT TODAY FOR WIZ017-029-032>034. WINTER WEATHER ADVISORY UNTIL NOON CDT TODAY FOR WIZ041. WINTER WEATHER ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ042. MN...WINTER STORM WARNING UNTIL NOON CDT TODAY FOR MNZ079-087-088-094- 095. WINTER WEATHER ADVISORY UNTIL NOON CDT TODAY FOR MNZ096. WINTER STORM WARNING UNTIL 10 AM CDT THIS MORNING FOR MNZ086. IA...WINTER STORM WARNING UNTIL NOON CDT TODAY FOR IAZ008-009-018-019. WINTER WEATHER ADVISORY UNTIL NOON CDT TODAY FOR IAZ010-029. && $$ SHORT TERM...DAS LONG TERM...BOYNE AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
627 AM CDT MON MAR 11 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY 346 AM CDT MON MAR 11 2013 AT 3 AM...THE SURFACE LOW WAS OVER NORTHERN LAKE MICHIGAN. THE 850 MB LOW TRACKED 50 TO 100 MILES FURTHER NORTH THAN ORIGINALLY ADVERTISED. THIS BROUGHT THE DRY SLOT INTO SOUTHWEST AND CENTRAL WISCONSIN AND PARTS OF NORTHEAST IOWA...THUS CUTTING OFF MUCH OF THE PRECIPITATION IN THESE AREAS. IT ALSO SHIFTED THE DEFORMATION AREA FURTHER NORTH INTO SOUTHEAST MINNESOTA AND NORTH CENTRAL WISCONSIN. THE 11.00Z MODELS ARE IN GOOD AGREEMENT THAT THE DEFORMATION AXIS WILL BECOME ORIENTATED NORTH-SOUTH EARLY THIS MORNING AND THEN MOVE SLOWLY EAST AND WEAKEN AS IT MOVES ACROSS THE FORECAST AREA. ADDITIONAL SNOW AMOUNTS WILL BE LESS THAN 2 INCHES. WITH VERY LITTLE SNOW FALLING SOUTHEAST OF A MAUSTON WISCONSIN TO OELWEIN IOWA LINE...DROPPED THE WINTER WEATHER ADVISORIES AND WARNINGS IN THESE AREAS. ALSO...DOWNGRADED THE WINTER STORM WARNING TO A WINTER WEATHER ADVISORY FOR FAYETTE AND WINNESHIEK COUNTIES IN NORTHEAST IOWA...HOUSTON COUNTY IN SOUTHEAST MINNESOTA...AND LA CROSSE AND MONROE COUNTIES IN WEST-CENTRAL WISCONSIN. FOR TONIGHT...ANOTHER WEAK WAVE WILL MOVE ACROSS EAST ACROSS THE AREA. THIS SYSTEM WILL BRING SOME LIGHT SNOW TO THE AREA...BUT THERE WILL BE LITTLE...IF ANY...ACCUMULATIONS FROM IT. ON TUESDAY...A MUCH STRONGER SHORT WAVE TROUGH WILL MOVE EAST THROUGH THE FORECAST AREA. DURING THE LATE MORNING AND AFTERNOON... 950-850 MB LAPSE RATES CLIMB TO AROUND 9C/KM AND CAPES WILL CLIMB UP 100 J/KG. THIS WILL RESULT IN THE DEVELOPMENT OF SCATTERED SHOWERS. SOUNDINGS SUGGEST TEMPERATURES WILL BE COLD ENOUGH ALOFT FOR THE PRECIPITATION TO BE IN THE FORM OF SNOW. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY 346 AM CDT MON MAR 11 2013 A FAIRLY ACTIVE NORTHWEST FLOW REMAINS ACROSS THE AREA THROUGH THIS TIME PERIOD. SHORT WAVES WILL BRING CHANCES OF PRECIPITATION ON THURSDAY...FRIDAY AND FRIDAY NIGHT...AND SUNDAY AND SUNDAY NIGHT. THE PRECIPITATION TYPES DURING THIS TIME FRAME IS HIGHLY DEPENDENT ON WHERE THE BAROCLINIC ZONE SETS UP. THEREFORE JUST WENT WITH A MIX OF RAIN AND SNOW FOR THESE TIME PERIODS. && .AVIATION...TODAY AND TONIGHT 627 AM CDT MON MAR 11 2013 AN ELONGATED AREA OF LOW PRESSURE WAS LOCATED FROM NORTHERN ILLINOIS INTO EASTERN WISCONSIN. DEFORMATION BAND OF SNOW WAS LOCATED OVER NORTHEAST IOWA INTO SOUTHEAST MINNESOTA...AFFECTING THE KRST TAF SITE WITH 1 1/2SM VISIBILITY IN SNOW. 11.08Z HRRR SHOWS THIS BAND TO TRANSLATE EASTWARD THIS MORNING AS THE LOW PULLS AWAY. THUS EXPECT VISIBILITIES TO DROP AT KLSE BETWEEN 14Z-17Z INTO THE 1-3SM RANGE. EXPECT CEILINGS TO REMAIN IFR AT KRST UNTIL 17Z THEN RISE INTO THE MVFR CATEGORY. AT KLSE...CEILINGS WILL REMAIN IN THE MVFR CATEGORY. THE SNOW WILL TAPER OFF EARLY THIS AFTERNOON...BUT THE MVFR CEILINGS WILL CONTINUE THROUGH THE REMAINDER OF THE TAF PERIOD. && .ARX WATCHES/WARNINGS/ADVISORIES... 346 AM CDT MON MAR 11 2013 WI...WINTER STORM WARNING UNTIL 10 AM CDT THIS MORNING FOR WIZ017-029- 032>034. WINTER WEATHER ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ041- 042. MN...WINTER STORM WARNING UNTIL 10 AM CDT THIS MORNING FOR MNZ079- 086>088-094-095. WINTER WEATHER ADVISORY UNTIL 10 AM CDT THIS MORNING FOR MNZ096. IA...WINTER STORM WARNING UNTIL 10 AM CDT THIS MORNING FOR IAZ008-009- 018-019. WINTER WEATHER ADVISORY UNTIL 10 AM CDT THIS MORNING FOR IAZ010- 029. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
449 AM EDT WED MAR 13 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 447 AM EDT WED MAR 13 2013 WV IMAGERY AND RUC ANALYSIS UPPER TROUGH IS STILL ROTATING OVER THE GREAT LAKES REGION THIS MORNING. THE ABUNDANT MOISTURE WITH THIS UPPER LOW AND 850MB TEMPERATURES AROUND -16C LED TO MODERATE TO HEAVY LAKE EFFECT SNOW OFF LAKE SUPERIOR YESTERDAY INTO THE OVERNIGHT HOURS. AS OF 2AM...THE SNOWFALL TOTAL AT OUR OFFICE HAD REACHED 8.7 INCHES. BUT MID LEVEL DRYING...SEEN ON THE 00Z KINL AND CWPL SOUNDINGS ALONG WITH IR SATELLITE OVER WESTERN LAKE SUPERIOR...HAD BROUGHT A QUICK END TO THE SNOW OVER THE WESTERN CWA SHORTLY AFTER MIDNIGHT AND RECENT RADAR TRENDS OVER THE CENTRAL AND EAST SHOW SIMILAR QUICK DECREASE. UPPER RIDGE AND SURFACE HIGH PRESSURE WILL BE BUILDING IN TODAY AND REMAINING INTO TONIGHT. THIS WILL CONTINUE TO PULL THE DRY AIR OVER THE AREA AND SHOULD BRING AN END TO THE LINGERING SNOW SHOWERS OVER THE EAST DURING THE MORNING HOURS. WITH THE QUICK DECREASE TO THE SNOW...DECIDED TO DROP THE REMAINING WINTER WX ADVISORIES OVER THE EAST. THE GUSTY WINDS TODAY WILL KEEP SOME BLOWING SNOW IN THE FORECAST...WITH THE BEST CHANCES NEAR LAKE SUPERIOR EAST OF MARQUETTE. BASED ON LATEST TRENDS...HAVE OPTED TO GO MORE A LITTLE MORE OPTIMISTIC ON THE CLOUD COVER FOR TODAY. THE QUICK TRANSITION TO VFR AND MID CLOUDS OVER THE WEST SHOWS A LACK OF LOW LEVEL MOISTURE EVENTHOUGH 850MB TEMPS ARE STILL AROUND -14C. THERE IS JUST ENOUGH TERRAIN ENHANCEMENT TO AID CLOUD COVER OVER THE WEST AND THAT COULD BE THE CASE TODAY...ESPECIALLY WITH SOME DIURNAL HEATING HELP. THUS...AFTER THE DEEPER MOISTURE DEPARTS THIS MORNING...TRANSITIONED TO A PARTLY CLOUDY SKY WITH THE GREATEST CLEARING NEAR THE WISCONSIN BORDER. HIGHS TODAY WILL REMAIN BELOW NORMAL WITH MOST LOCATIONS IN THE MID-UPPER 20S. FOR TONIGHT...MODELS STILL HINTING AT A INCREASE IN THE MOISTURE IN THE 925-875MB RANGE LATE THIS AFTERNOON INTO THIS EVENING FROM THE KEWEENAW SOUTHEAST THROUGH MARQUETTE/ALGER COUNTIES. 875MB TEMPS AROUND -12.5C WOULD SUPPORT ENOUGH INSTABILITY FOR SOME SNOW SHOWERS...BUT CONCERN IS THE DEPTH OF THE CLOUD LAYER WHICH WILL LIKELY ONLY BE 2-3KFT. THERE WAS A THIN AREA OF CLOUDS THIS PAST EVENING WHERE THE MODELS ARE SHOWING THE LOW MOISTURE...BUT IT HAS SINCE DISSIPATED. THAT MOISTURE MAY STILL BE PRESENT AND WITH THE INFLUENCE OF LAKE SUPERIOR...PUT IN A MENTION OF ISOLATED FLURRIES FOR ALGER/LUCE/SCHOOLCRAFT COUNTIES. OTHERWISE...HIGH PRESSURE SHOULD BE IN PLACE OVER THE AREA AND LEAD TO A QUIET NIGHT. THE WESTERN CWA WILL LIKELY BE MOSTLY CLEAR DURING THE EVENING HOURS BEFORE MID/HIGH CLOUDS START STREAMING IN AHEAD OF THE NEXT SHORTWAVE DROPPING THROUGH THE NORTHWEST FLOW ALOFT. THINKING THE HIGH CLOUDS WILL BE IN BY MIDNIGHT AND THEN THEY WILL THICKEN/LOWER THROUGH THE NIGHT AND COVER ALL OF THE WESTERN CWA BY MORNING. THIS GIVES CONCERN TO LOWS FOR TONIGHT...AS THE CLOUD COVER WILL HAVE A GREAT INFLUENCE ON TEMPERATURES WITH THE OTHERWISE GOOD RADIATIONALLY COOLING NIGHT WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF NORMAL. THE REGIONAL GEM...WHICH USUALLY DOES WELL IN THESE RADIATIONAL AND CLOUD SITUATIONS HAS LOWS AROUND ZERO AROUND IRON COUNTY AND THAT COMBINED WITH THE PREVIOUS FORECAST SEEMS LIKE THE WAY TO GO. UNFORTUNATELY IN THESE SITUATIONS...AN HOUR OR TWO DIFFERENCE IN CLOUD COVER TIMING CAN EASILY BUST THE FORECAST IN EITHER DIRECTION. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 447 AM EDT WED MAR 13 2013 UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE OVER THE WESTERN U.S. WITH A TROUGH OVER THE EASTERN U.S. 12Z THU. THE RIDGE GETS FLATTENED WITH TIME ON FRI WITH A SHORTWAVE MOVING INTO THE NORTHERN PLAINS LATE FRI. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE AND DEEPER MOISTURE MOVING IN ON FRI AND FRI NIGHT. FOR THIS FORECAST...NOT REAL CONFIDENT IN THE STORM SYSTEM FOR FRIDAY FOR NOW. ECMWF AND GFS ARE TAKING THE SYSTEM A BIT FURTHER SOUTH WHILE THE NAM IS NORTH WITH IT. NO REAL CONTINUITY IN THE MODELS EITHER WITH THEIR FORECASTS...SO CONFIDENCE IS FAIRLY LOW. WITH THE DIFFERENCE IN PLACEMENT OF THE SYSTEM...THIS WILL AFFECT HOW COLD 850 MB TEMPERATURES ARE. 12Z ECMWF WAS MUCH WARMER AT 850 MB WITH TEMPERATURES OF -4C TO -8C ON FRI. 00Z ECMWF NOW IS COLDER WITH 850 MB TEMPERATURES -8C TO -14C WHILE THE GFS IS -10C TO -12C. WITH NORTH WINDS AND DELTA-T GREATER THAN 11C...THIS IS ENOUGH FOR LAKE ENHANCEMENT OF THE SNOW. COULD SEE UP TO 5 INCHES OF SNOW ON FRIDAY INTO FRIDAY NIGHT AND WILL PROBABLY NEED SOME HEADLINES UP FOR FRIDAY AND FRIDAY NIGHT. WENT LIKELY POPS ON FRIDAY FOR THE LAKE ENHANCEMENT. FOR THU...LOOKS LIKE A SYSTEM WILL STAY TO THE WEST OF THE AREA AND ENDED UP GOING DRIER FOR THE FORECAST AS 850 MB TEMPERATURES ARE NOT COLD ENOUGH FOR LAKE ENHANCEMENT. OVERALL...LOWERED HIGH TEMPERATURES A COUPLE DEGREES ALONG WITH OVERNIGHT LOWS DUE TO TRENDS LATELY WHERE FORECASTS HAVE BEEN TOO WARM. IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE NORTHERN U.S. 12Z SAT. THIS TROUGH REMAINS OVER THE AREA ON SUN. A TROUGH DIGS IN THE NORTHERN PLAINS ON MON AND AFFECTS THE UPPER GREAT LAKES MON NIGHT INTO TUE. TEMPERATURES CONTINUE TO LOOK COLDER THAN NORMAL THROUGH THE PERIOD WITH NO WARM UP IN SIGHT. WITH COLD TEMPERATURES IN PLACE...LAKE EFFECT SNOW WILL BE POSSIBLE THIS EXTENDED PERIOD FOR SAT AND SUNDAY. ANOTHER SYSTEM ARRIVES FOR MON INTO TUE AND BRINGS A CHANCE FOR SNOW. THIS SYSTEM WILL HAVE TO BE WATCHED AS COULD BE ANOTHER SIGNIFICANT WINTER STORM AND WILL HIT UP THIS POTENTIAL IN THE HWO PRODUCT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 130 AM EDT WED MAR 13 2013 WITH DISTURBANCE/TROF EXITING...DRIER AIR IS FLOWING INTO THE AREA...RESULTING IN MUCH IMPROVED CONDITIONS FROM EARLIER IN THE NIGHT. AT KIWD/KCMX/KSAW...MVFR/VFR CONDITIONS SHOULD PREVAIL OVERNIGHT. SOME LINGERING SHSN ARE POSSIBLE FOR THE NEXT FEW HRS AT KSAW...BUT SHOULD ONLY RESULT IN BRIEF REDUCTION OF VIS BLO MVFR. WITH CONTINUED DRYING...MVFR CIGS SHOULD TEND TO SCATTER OUT TODAY OR LIFT JUST ABOVE 3KFT...AND THAT COULD HAPPEN AS EARLY AS THE MORNING HRS. VFR CONDITIONS WILL ROUND OUT THE FCST DURING THE EVENING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 447 AM EDT WED MAR 13 2013 A SURFACE TROUGH THAT DROPPED SOUTH ACROSS LAKE SUPERIOR LAST NIGHT WILL CONTINUE TO PRODUCE NORTHWEST WINDS OF 20-30KTS OVER THE EASTERN LAKE TODAY. BUT WITH THE PARENT LOW MOVING NORTHEAST THROUGH QUEBEC...THIS TIGHT PRESSURE GRADIENT WILL WEAKEN THIS AFTERNOON AS HIGH PRESSURE MOVES OVER THE LAKE TONIGHT. WINDS HAVE DROPPED BELOW GALES AT OBSERVATION SITES AND HAVE DROPPED THE GALE WARNING. THERE COULD STILL BE A FEW GALE FORCE GUSTS OVER THE EASTERN LAKE DURING THE MORNING...BUT THE COVERAGE SHOULD BE LIMITED. TONIGHT/S HIGH WILL BEGIN TO SHIFT EAST ON THURSDAY...ALLOWING A COLD FRONT TO DROP SOUTHEAST ACROSS LAKE SUPERIOR ON THURSDAY NIGHT. A SECONDARY LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST FROM THE UPPER MISSISSIPPI VALLEY TO THE LOWER GREAT LAKES ON FRIDAY INTO FRIDAY NIGHT...SHIFTING WINDS TO A NORTHERLY DIRECTION AT 15-30KTS. BEHIND THIS LOW...A LARGE AREA OF HIGH PRESSURE WILL MOVE INTO THE UPPER GREAT LAKES FOR SATURDAY. ANOTHER WEAK TROUGH WILL MOVE ACROSS LAKE SUPERIOR ON SATURDAY NIGHT BEFORE THE HIGH PRESSURE RIDGE RESETS OVER THE UPPER GREAT LAKES. THERE WILL BE FREEZING SPRAY OVER CENTRAL AND EASTERN LAKE SUPERIOR THROUGH THIS EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...SRF LONG TERM...07 AVIATION...ROLFSON/SRF MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
133 AM EDT WED MAR 13 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 408 PM EDT TUE MAR 12 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF CENTERED OVER THE GREAT LKS BTWN UPR RDGS ALONG THE W COAST AND OFF THE E COAST. WITH DEEP CYC NW FLOW...ABUNDANT MSTR SHOWN ON THE 12Z GRB RAOB...AND H85 TEMPS IN THE -13C TO -16C RANGE...SHSN HAVE BEEN COMMON OVER THE CWA TODAY UNDER CLDY SKIES...ESPECIALLY NEAR LK SUP IN AREAS FAVORED BY THE NW LLVL FLOW. THE SN HAS BEEN RATHER FLUFFY AS MODEL SDNGS INDICATE THE DGZ IS SEVERAL THOUSAND FEET DEEP GIVEN FVRBL H85 TEMPS. THERE IS A SHRTWV DROPPING SEWD THRU MN ACCOMPANIED BY A FAIRLY WELL DEFINED TROF AT H85-7. UPSTREAM OBS AT GRAND MARAIS ON THE MN NORTH SHORE AND AT THUNDER BAY IN ONTARIO INDICATE SOME HEAVIER SHSN ACCOMPANY THIS TROF PASSAGE FARTHER TO THE E-SE AWAY FM DRIER AIR SHOWN ON THE 12Z INL/YPL RAOBS. APRCHG FCST ISSUANCE... SOME OF THE HEAVIER SHSN HAVE ARRIVED OVER THE WRN COUNTIES. CMX HAS REPORTED VSBY DOWN TO 1/4SM AT TIMES...AND REPORTS FM GOGEBIC COUNTY INDICATE AS MUCH AS 5 INCHES OF SN FELL THERE THRU 18Z. LATE THIS AFTN/TNGT...AS SHRTWV IN MN DIGS SEWD...GUIDANCE SHOWS PRONOUNCED H85 WSHFT ASSOCIATED WITH TROF PASSAGE AS WELL AS AREA OF H85-5 QVECTOR CNVGC CROSSING THE CWA NW-SE. EXPECT SHSN TO INCRS IN INTENSITY WITH THIS ENHANCED SUPPORT IN PRESENCE OF DEEP MSTR. FCST SDNGS CONTINUE TO SHOW UVV FOCUSED IN THE DGZ...SO EXPECT HI SN/ WATER RATIOS AOA 20:1. LATER TNGT IN THE WAKE OF THE TROF PASSAGE... DEEP LYR QVECTOR DVGC/SUBSIDENCE IN THE WAKE OF THE SHRTWV/TROF WL CONSPIRE TO LOWER INVRN BASES DOWN TO 2-3K FT AGL. WITH ARRIVAL OF LLVL DRY AIR SHOWN ON THE 12Z INL/YPL RAOBS...EXPECT LES TO DIMINISH FAIRLY STEADILY AFT 06Z. OVERALL...SHIFTING WINDS FM NW TO N AND LIMITED 6-9HR WINDOW OR SO FOR HEAVIER SHSN WL LIMIT TOTAL SN FALL...SO EXPECT SN TOTALS TO REMAIN WITHIN ADVY LIMITS DESPITE FVRBL SN/WATER RATIOS. THGE ONLY EXCEPTION IS OVER THE FAR W...WHERE SOME HEAVY SN FELL DURING THE AFTN AS NOTED ABV. SINCE THERE WL BE PERIODS OF +SHSN THRU THIS EVNG IN THAT AREA WITH SOME FOCUSED LLVL CNVGC IN FVRBL CYC NNW FLOW...OPTED TO UPGRADE ADVY TO A WARNING FOR GOGEBIC/ONTONAGON COUNTIES. ALSO EXTENDED ADVY OVER THE ERN ZNS THRU 12Z GIVEN MORE PERSISTENT FORCING/DEEPER MSTR THERE. WED...AXIS OF MUCH DRIER AIR WITH H85 DEWPTS AS LO AS -40C AS WELL AS DEEP LYR QVECTOR DVGC/SUBSIDENCE UNDER STEADILY RISING H5 HGTS FOLLOWING SHIFT OF UPR TROF AXIS TO THE E WL RESULT IN MAINLY DRY WX AFTER LINGERING SHSN OVER MAINLY THE E DIMINISH IN THE MRNG. IN FACT...FCST SDNGS SUG SKIES MAY TURN MOSUNNY IN THE AFTN... ESPECIALLY NEAR LK SUP WITH A TENDENCY FOR CLRG OVER THE WATER UNDER STRENGTHENING LATE WINTER SUNSHINE. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 408 PM EDT TUE MAR 12 2013 TO START THE LONG TERM PERIOD...OVERVIEW OF LARGE SCALE FEATURES TROUGH OVER GREAT LAKES AND EASTERN CANADA WITH BROAD RIDGING EXTENDING WELL UPSTREAM INTO EASTERN PORTION OF PACIFIC OCEAN. FARTHER UPSTREAM TROUGHING IS PRESENT NORTH OF HAWAII. THAT TROUGH IS ESSENTIALLY EXTENSION OF TROUGHING RESIDING OVER NORTHERN PORTIONS OF CANADA ON NORTHERN PORTION OF WESTERN CONUS RIDGE. OVER TIME...TROUGH OVER GREAT LAKES SYNCS UP WITH TROUGHING OVER NORTHERN CANADA RESULTING IN FAST AND ACTIVE WEST-NORTHWEST FLOW ACROSS MOST OF THE CONUS THROUGH THE UPCOMING WEEKEND. TWO SHORTWAVES PROGGED TO DROP THROUGH IN THIS FLOW PATTERN INTO THIS WEEKEND. FIRST WAVE ALONG WITH WEAK SFC-H85 LOW-LEVEL WARM AIR ADVECTION GLANCES UPR LAKES TO WEST ON THURSDAY. WAVE IS DIGGING INTO THE MEAN TROUGH WHICH FAVORS MORE OF A SOUTH AND/OR WEST TRACK AND IS PRETTY PROGRESSIVE. ALSO LOOKS LIKE ANY UPPER JET SUPPORT REMAINS WEST OF UPR MICHIGAN. MODELS VARY WILDLY FROM SOUTH TO NORTH WHERE THE MOST QPF/SNOW IS EXPECTED. GEM-NH ON SOUTHERN EXTREME... TRACKING ACROSS IOWA...WHILE NAM IS OVER WESTERN UPR MICHIGAN. NAM IS ON NORTH EDGE OF EVEN SREF...SO IT IS CERTAINLY AN OUTLIER. GFS AND ECMWF IN BTWN...BUT ARE STILL MAINLY OVER WISCONSIN. SINCE THERE IS A SLIGHT EASTWARD TREND IN MODELS...WILL BRING CHANCE POPS OVER WESTERN CWA ON THURSDAY. OTHER ISSUE...PREVIOUSLY MENTIONED BY MID SHIFT...IS POSSIBLE FREEZING DRIZZLE LATER THURSDAY INTO THURSDAY NIGHT. BASED ON FORECAST SOUNDINGS...WI BORDER/SCNTRL...WILL HAVE BEST CHANCE SEEING THIS ONCE ANY SNOW DECREASES. ELSEWHERE...THINK TOO MUCH DRIER AIR IS AROUND BLO H85 TO HAVE IN THERE. SINCE AM NOT CERTAIN WHERE ULTIMATELY THE STEADIER SNOW SETS UP OVR CWA...IF IT DOES AT ALL...WILL KEEP FZDZ OUT OF FCST. COUPLE OF SUBTLE THINGS HAPPEN LATER THURSDAY INTO THURSDAY NIGHT THAT MAY HAVE LARGE IMPACT ON FORECAST FOR FRIDAY. ALL MODELS INDICATE STRONGER NORTHERN STREAM WAVE TRACKS WELL TO THE NORTH OVER NORTHWEST ONTARIO THURSDAY NIGHT. WE ARE GOOD THERE. TROUBLE IS THAT SAME MODELS DIFFER ON HOW FAR SOUTH TO BRING LOW-LEVEL COLD AIR IN WAKE OF SHORTWAVE BY FRIDAY MORNING. GEM-NH FARTHER SOUTH WITH COLD AIR AND TRENDS FROM GFS ALSO INDICATE FARTHER SOUTH LOW-LEVEL TEMPERATURE GRADIENT AT SFC-H85. ECMWF NOT AS COLD THOUGH. LOCATION OF TIGHTER LOW-LEVEL TEMPERATURE GRADIENT COULD PAVE THE WAY FOR WHERE HEAVIER QPF/SNOW SETS UP ON FRIDAY AS SHORTWAVE AND SFC-H85 LOWS MOVE IN FROM NORTHERN PLAINS. THIS SECOND SHORTWAVE IS MUCH STRONGER THAN ONE MOVING THROUGH 24 HR EARLIER AND HAS POTENTIAL TO BRING WIDESRPEAD SNOW TO UPPER LAKES ON FRIDAY. WHERE EVER LOW-LEVEL BAROCLINIC ZONE SETS UP THERE ARE ENHANCING FACTORS THAT MAY RESULT IN SWATH OF MODERATE TO HEAVY SNOW INCLUDING DIVERGENCE ALOFT FROM RIGHT ENTRANCE REGION OF JET STREAK DROPPING INTO GREAT LAKES FROM ONTARIO...DECENT MOISTURE ADVECTION WITH H7 MIXING RATIOS OVR 3G/KG...AND OVERALL STRENGTHENING SFC-H85 LOWS/LOW-LEVEL FLOW. ADVY LEVEL SNOWS CERTAINLY POSSIBLE. INCREASED POPS TO LIKELY OVER WEST AND SOUTH...WHERE MODEL AGREEMENT IS HIGHER THAT SNOW OCCURS. WWD DAY 3 GRAPHICS INDICATE UP TO 4 INCHES OVER WEST THIRD OF CWA ON FRIDAY. IF FARTHER NORTH ECMWF AND GEM-NH ARE CORRECT...THEN LIKELY POPS WILL BE NEEDED FOR MOST AREAS ON FRIDAY. AT FIRST GLANCE A MAINLY QUIET WEEKEND AS HIGH PRESSURE IS MAIN FEATURE OVER REGION. COULD BE RE-INFORCING SHOT OF COLDER AIR AND SOME DEEPER MOISTURE COME IN LATER SATURDAY AND SATURDAY NIGHT. GFS/ECMWF INDICATE INCREASE IN POPS DURING THAT TIME. KEPT CHANCY POPS IN ALONG LK SUPERIOR WITH ADDED POTENTIAL FOR LK EFFECT AS H85 TEMPS DROP INTO THE -15C TO -20C RANGE. RECORD SETTING WARMTH OF MID MARCH IN 2012 WILL BE BUT A DISTANT MEMORY COMPARED TO THE CHILL OF THIS YEAR. COOL AND ACTIVE PATTERN CONTINUES INTO EARLY NEXT WEEK...AND PROBABLY EVEN INTO LATER MARCH AS WELL. CERTAINLY NOT DONE WITH WINTER YET. DEEPER SHORTWAVE TROUGH EMERGES FROM TROUGHING OVER NORTHERN CANADA AND EVENTUALLY TRACKS ACROSS ROCKIES LATE IN THE WEEKEND. THIS TROUGH THEN DEEPENS ACROSS THE MIDDLE CONUS MONDAY AND MOVES INTO THE GREAT LAKES ON TUESDAY. DEEPENING LOW PRESSURE SYSTEM RESULTS WHICH DRAWS UP GULF MOISTURE AND COULD LEAD TO SIGNIFICANT SNOW SOMEWHERE UPPER MIDWEST THROUGH THE GREAT LAKES...INCLUDING UPR MICHIGAN. OVERALL THE ECMWF IS DEEPER AND FARTHER NORTH WITH SFC LOW...THOUGH LATEST RUN BACKED OFF WITH STRENGTH OF LOW. GFS IS MORE SUPPRESSED WITH TRACK OF SFC LOW. WPC...FORMALLY HPC...HAND DRAWN PROGS BTWN THE TWO WITH LOW MOVING ACROSS LOWER LAKES AND UPR MICHIGAN JUST ON THE FRINGE. CONSENSUS POPS ARE IN THE CHANCE RANGE WHICH IS FINE AT THIS POINT. GIVEN NORTHEAST WINDS AND COOLER AIR...INCREASED POPS CLOSER TO LK SUPERIOR. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 130 AM EDT WED MAR 13 2013 WITH DISTURBANCE/TROF EXITING...DRIER AIR IS FLOWING INTO THE AREA...RESULTING IN MUCH IMPROVED CONDITIONS FROM EARLIER IN THE NIGHT. AT KIWD/KCMX/KSAW...MVFR/VFR CONDITIONS SHOULD PREVAIL OVERNIGHT. SOME LINGERING SHSN ARE POSSIBLE FOR THE NEXT FEW HRS AT KSAW...BUT SHOULD ONLY RESULT IN BRIEF REDUCTION OF VIS BLO MVFR. WITH CONTINUED DRYING...MVFR CIGS SHOULD TEND TO SCATTER OUT TODAY OR LIFT JUST ABOVE 3KFT...AND THAT COULD HAPPEN AS EARLY AS THE MORNING HRS. VFR CONDITIONS WILL ROUND OUT THE FCST DURING THE EVENING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 408 PM EDT TUE MAR 12 2013 UNDER THE TIGHTENING PRES GRADIENT IN THE WAKE OF A TROF PASSAGE THIS EVENING...EXPECT A N GALE UP TO 35 KTS OVER PORTIONS OF NCENTRAL LAKE SUP MUCH OF TONIGHT. FREEZING SPRAY WILL BE WIDESPREAD. AS THE GRADIENT WEAKENS LATE TONIGHT THRU WED...THE WINDS WILL GRADUALLY DIMINISH AND BACK TOWARD THE NW WITH APPROACH OF HI PRES FROM THE W. WINDS OF LESS THAN 20 KTS PERSIST INTO THURSDAY AS HIGH PRESSURE SLIDES ACROSS. SOUTHWESTERLY RETURN FLOW ON BACK SIDE OF HIGH MAY GET GUSTY OVER 25 KTS BY THU NIGHT. COLD FRONT SHIFTS THROUGH OVERNIGHT THURSDAY NIGHT WITH NORTHWEST WINDS TRYING TO REACH 30 KTS. NORTHERLY WINDS TO 25 KTS CONTINUE INTO FRI. WINDS DIMINISH THROUGH REST OF WEEKEND AS HIGH PRESSURE RETURNS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MIZ006- 007-085. LAKE EFFECT SNOW WARNING UNTIL 2 AM EDT /1 AM CDT/ EARLY THIS MORNING FOR MIZ002-009. WINTER WEATHER ADVISORY UNTIL 2 AM EDT EARLY THIS MORNING FOR MIZ001-003-004-084. WINTER WEATHER ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR MIZ005. LAKE SUPERIOR... GALE WARNING UNTIL 5 AM EDT EARLY THIS MORNING FOR LSZ243-244- 248>250-264>266. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...JLA AVIATION...ROLFSON/SRF MARINE...KC/JLA
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1152 PM CDT TUE MAR 12 2013 .AVIATION... 06Z TAFS FOR KOMA...KOFK...KLNK VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. THE SC DECK THAT WAS AFFECTING THE TAF SITES EARLIER THIS EVENING HAS SHIFTED EAST LEAVING GENERALLY CLEAR SKIES CURRENTLY. SOME MID AND HIGH LEVEL CLOUDS WILL INCREASE TOWARD MORNING...BUT THESE ARE EXPECTED TO BE AOA 8 K FT. WINDS WILL CONTINUE TO DIMINISH OVERNIGHT BEFORE BECOMING SOUTH ON WED WITH SPEEDS BELOW 12 KT. && .PREV DISCUSSION... /ISSUED 325 PM CDT TUE MAR 12 2013/ SHORT TERM...TONIGHT THROUGH FRIDAY. MOSTLY CLOUDY CONDITIONS HAD DEVELOPED THROUGH THE DAY IN THE NORTHEASTERN 2/3 OF THE FORECAST AREA...WITHIN AN AREA CYCLONIC NORTHWESTERLY FLOW AROUND STRONG CLOSED LOW PRESSURE ACROSS THE WESTERN GREAT LAKES. A FEW FLURRIES HAD DEVELOPED IN NORTHEAST NEBRASKA AND NORTHWEST IOWA...BUT MORE IMPORTANTLY...WINDS GUSTING 30 TO 35 MPH HAS ALSO CREATED AREAS OF BLOWING SNOW OUT IN OPEN RURAL AREAS. THIS WAS CREATING SOME VISIBILITY ISSUES...AS WELL AS SOME SLICK ROADWAYS. THIS TREND WILL CONTINUE THROUGH EARLY EVENING UNTIL THE WINDS BEGIN TO DIMINISH BY 5 TO 7 PM...ALTHOUGH ISOLATED FLURRIES COULD STILL BE POSSIBLE IN WESTERN IOWA FOR ANOTHER HOUR OR TWO BEYOND THAT. CLOUD TRENDS OVERNIGHT WILL BE ALSO BE TRICKY TO FORECAST. SURFACE HIGH PRESSURE RIDGE WILL CONTINUE MOVING IN FROM THE WEST. THIS WILL ALLOW SOME OF THE DIURNAL CLOUDS TO DISSIPATE ON THE SOUTHWEST EDGE...HOWEVER AS WITH PAST SEVERAL SYSTEMS...THE RAP SEEMS TO HAVE A MUCH BETTER HANDLE ON THE LOW LEVEL CLOUDINESS...LINGERING IT MUCH LONGER THAN OTHER MODELS WOULD SUGGEST. THIS COULD ALSO AFFECT HOURLY TEMPERATURES...AS SKIES CLEAR IN SOME AREAS AND WINDS BECOME LIGHT AND PERHAPS EVEN CALM IN OUR WESTERN CWA. SOME CIRRUS COULD ALSO BEGIN TO MOVE INTO THESE SAME AREAS TOWARD DAYBREAK...AS AREAS ALONG/EAST OF THE MISSOURI RIVER FINALLY BEGIN TO SCATTER OUT. SOUTHEASTERLY SURFACE FLOW DEVELOPS ON WEDNESDAY AS THE MID/HIGH CLOUDS MOVE ACROSS THE REGION. TEMPS SHOULD WARM INTO THE MID 30S OVER THE SNOWFIELD, AND THE LOWER/MID 40S ELSEWHERE. MEANWHILE...WARM AIR ADVECTION ALOFT WILL CONTINUE THROUGH THE REMAINDER OF THE PERIOD. ANOTHER WEAK CLIPPER SYSTEM WILL MOVE THROUGH THE DAKOTAS WEDNESDAY NIGHT. WHILE THIS COULD GENERATE A SPRINKLE OR TWO IN OUR AREA AND MAYBE EVEN MEASURABLE PRECIP JUST TO OUR NORTH/NORTHEAST...WILL MAINTAIN A DRY FORECAST AT THIS TIME WITH PARTLY TO MOSTLY CLOUDY SKIES EXPECTED. THIS SHOULD TRANSLATE TO DECENT WARMING ON THURSDAY...UPPER 40S OVER THE DIMINISHING SNOW PACK...WHICH IS STILL UNDER MAV/MET GUIDANCE... TO THE LOWER 60S OVER THE SNOW FREE AREAS. FRIDAY SHOULD BE THE WARMEST DAY OF THE WEEK AS TEMPERATURES WARM SIGNIFICANTLY AHEAD OF THE NEXT COLD FRONT EXPECTED FOR THE WEEKEND. TEMPS FRIDAY SHOULD REACH THE MID 50S WHERE SOME SNOW STILL EXISTS...AND EVEN IN THE MID TO UPPER 60S ELSEWHERE. DEWALD LONG TERM...FRIDAY NIGHT THROUGH TUESDAY. THE EXTENDED PERIOD LOOKS TO BE A PERIOD OF BELOW NORMAL TEMPERATURES WITH UNSETTLED WEATHER SATURDAY THROUGH MONDAY. WEATHER DISTURBANCES MOVING THROUGH THE WEST AND NORTHWEST FLOW ALOFT AND WILL BRING CHANCES OF PRECIPITATION. THE LONG RANGE MODELS ARE NOT IN GOOD AGREEMENT IN SPECIFIC TIMING AND STRENGTH OF THE SYSTEMS...THUS LOW CONFIDENCE IN PINNING DOWN THE THERMAL STRUCTURE AND TIMING. A WEAK WAVE APPEARS TO MOVE THROUGH THE CENTRAL/NORTHER PLAINS SATURDAY AND SATURDAY NIGHT...AND THE GFS LINGERS IT INTO SUNDAY...WITH SNOW...SLEET...AND RAIN POSSIBLE. SUNDAY NIGHT INTO MONDAY...ANOTHER STRONGER SYSTEM MOVES THROUGH. THE EC IS STRONGER WITH THE WAVE...FARTHER NORTH WITH THE PRECIP AND MOVES IT THROUGH FASTER WITH MORE COLD AIR AND STRONGER WINDS AVAILABLE. FOR NOW HAVE CHANCE POPS FOR RAIN OR SNOW MENTIONED FOR SUNDAY NIGHT AND MONDAY. ZAPOTOCNY && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
253 AM EDT WED MAR 13 2013 .SYNOPSIS... HIGH PRESSURE WILL BUILD TOWARD THE REGION FROM THE WEST TODAY THROUGH THURSDAY. A CLIPPER LOW WILL TRACK RAPIDLY SOUTHEAST INTO THE MID ATLANTIC AND CAROLINAS THURSDAY NIGHT. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... AS OF 930 PM TUESDAY... THROUGH TONIGHT: SKIES HAVE CLEARED ACROSS ALL OF CENTRAL NC AS THE COLD FRONT WHICH BROUGHT TODAY`S RAIN HAS SHIFTED TO COASTAL SECTIONS AND IS POISED TO MOVE OFFSHORE... PROPELLED BY COOL HIGH PRESSURE EXTENDING FROM CENTRAL CANADA DOWN THROUGH THE PLAINS AND LOWER MISS VALLEY. THE DIFFERENCE BETWEEN THE 00Z SOUNDINGS AT MHX (SOME LINGERING MOISTURE BELOW 850 MB) AND GSO (VERY DRY AIR THROUGH THE COLUMN) TELLS THE STORY... AS DOES THE WATER VAPOR IMAGERY SHOWING WELL THE SLUG OF DRY AIR SWEEPING TO THE NE THROUGH CENTRAL NC. UPPER LEVEL TRAJECTORIES DO SUGGEST HOWEVER THAT THE HIGH CLOUDS NOW STREAMING ACROSS ARK AND THE MEMPHIS AREA WILL SWEEP ACROSS NC TOWARD MIDNIGHT AND DURING THE OVERNIGHT HOURS... ALSO INDICATED BY THE RAP SOUNDINGS. WILL INCLUDE A THIN VEIL OF CLOUDS OVERNIGHT... BUT OTHERWISE SKIES SHOULD BE CLEAR. AS THE SURFACE RIDGE BUILDS IN OVERNIGHT WITH NORTHEASTERLY SURFACE WINDS AND COLD AIR ADVECTION... THICKNESSES ARE EXPECTED TO PLUMMET... FROM MUCH ABOVE NORMAL READINGS TODAY TO JUST BELOW NORMAL READINGS BY MORNING... ALTHOUGH THE MORE SIGNIFICANT DROP COMES WEDNESDAY INTO WEDNESDAY NIGHT WITH THE ARRIVAL OF THE POLAR FRONT. BOTH TEMPS AND DEW POINTS ARE TRENDING VERY CLOSE TO THE FORECAST PACE...AND LOWS OF 34-42 STILL LOOK REASONABLE. -GIH WEDNESDAY AND WEDNESDAY NIGHT: POTENT SHORTWAVE ENERGY UPSTREAM OVER MINNESOTA WILL DIG SOUTHEAST INTO THE TN VALLEY TONIGHT AND THEN THROUGH THE CAROLINAS AND VIRGINIA ON WEDNESDAY. AS THE POTENT VORTMAX SWINGS THROUGH THE AREA...STRONG DCVA AIDED BY COOLING ALOFT WILL RESULT IN STRONG MID AND UPPER LEVEL ASCENT. AIRMASS WILL BE TOO DRY TO SUPPORT OTHER THAN A PERIOD OF A PERIOD OF BROKEN TO OVERCAST MID CLOUDS WEDNESDAY AFTERNOON. AN ATYPICALLY COLD AIRMASS ALOFT (H85 TEMPS 1-2 STD DEVIATIONS BELOW NORMAL)IN THE PRESENCE OF DEEP VERTICAL MIXING WILL RESULT IN BELOW NORMAL TEMPERATURES WITH BREEZY NWLY WIND GUSTS BETWEEN 20 TO 25KTS. BOTH THE DRY-ADIABATIC AND LOW-LEVEL THICKNESS TEMPERATURES SCHEME SUGGEST AFTERNOON HIGHS A GOOD 5 TO 8 DEGREES BELOW STATISTICAL MOS GUIDANCE. HOWEVER...CONSIDERING THE EVER INCREASING SUN ANGLE THIS TIME OF YEAR...AM CONCERNED CURRENT FORECAST MAY BE A TOUCH TOO COOL...BUT THE EXPECTED PERIOD OF BROKEN MID-LEVEL CLOUD COVER SHOULD HELP. HIGHS NEAR 50 NW TO MID/UPPER 50S SOUTHEAST. A SECONDARY ROUND OF LOW-LEVEL COLD ADVECTION WILL OCCUR WEDNESDAY EVENING/NIGHT IN ASSOCIATION WITH RENEWED LOW-LEVEL NWLY FLOW IN THE WAKE OF THE EXITING UPPER LEVEL TROUGH. MINS FOR THE SECOND CONSECUTIVE NIGHT WILL BE DRIVEN BY CAA. LOWS WED NIGHT IN THE UPPER 20S TO LOWER 30S. -CBL && .SHORT TERM /THURSDAY THROUGH FRIDAY/... AS OF 320 PM TUESDAY... A STRONG UPPER LEVEL TROUGH WILL STILL BE IN PLACE ALONG THE EASTERN US ON THURSDAY. THIS...ALONG WITH CONTINUED COLD AIR ADVECTION (NORTHWESTERLY WINDS OF 10-15 MPH WILL LEAD TO ANOTHER DAY OF BELOW NORMAL TEMPS. HIGHS ARE ONLY EXPECTED TO BE IN THE LOW 50S (POSSIBLY STRUGGLING TO EVEN REACH 50 DEGREES IN SOME LOCATIONS). THE UPPER LEVEL TROUGH AXIS WILL MOVE OFFSHORE THURSDAY NIGHT...BUT A DISTURBANCE WITHIN THE NORTHWEST FLOW ALOFT WILL MOVE SOUTHEASTWARD ACROSS THE REGION THURSDAY NIGHT INTO FRIDAY MORNING. IT STILL APPEARS THE MAIN IMPACT FROM THIS FEATURE WILL BE AN INCREASE IN MID LEVEL CLOUD COVER AS THE BOUNDARY LAYER IS PROGGED TO BE RATHER DRY. HOWEVER...CANNOT COMPLETELY SOME SPRINKLES OR A LIGHT SHOWER... ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. DESPITE CLOUD COVER...OVERNIGHT LOWS WILL GENERALLY BE WITHIN A DEGREE OR TWO OF FREEZING. CLOUDS WILL DECREASE THROUGHOUT THE DAY ON FRIDAY AS SUBSIDENCE INCREASES ON THE BACKSIDE OF THE DEPARTING SHORTWAVE. AS HEIGHTS INCREASE SOME...TEMPS WILL BEGIN TO MODERATE...WITH HIGHS IN THE MID/UPPER 50S AND OVERNIGHT LOWS IN THE MID/UPPER 30S EXPECTED. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 250 AM WEDNESDAY... FRIDAY NIGHT THROUGH SUNDAY NIGHT: THE H85 RIDGE OVER THE GULF SHOULD DEAMPLIFY AS A LOW PRESSURE SYSTEM MOVES ACROSS THE GREAT LAKES REGION FRIDAY NIGHT INTO SATURDAY. A GOOD DEAL OF UNCERTAINTY STILL REMAINS BETWEEN THE 00Z GFS AND 12Z ECMWF WITH REGARD TO STRENGTH AND TIMING OF THE SYSTEM AND ASSOCIATED BACKDOOR COLD FRONT...WHICH WILL IN TURN HAVE AN IMPACT ON TEMPS AND PRECIP THROUGH THE PERIOD. THE ECMWF TENDS TO AMPLIFY THE TROUGH A BIT MORE THAN THE 00Z GFS... HOWEVER BOTH MODELS AGREE ON A WEST TO EAST ORIENTED FRONTAL BOUNDARY IN THE VICINITY OF CENTRAL NC SATURDAY THROUGH SUNDAY NIGHT. THE GFS PLACES THE FRONT IN THE VICINITY OF THE NC/SC BORDER AND THE ECMWF PLACES IT FARTHER NORTH...NEAR THE NC/VA BORDER. THIS DIFFERENCE HAS SIGNIFICANT IMPACTS ON PRECIP LOCATION AND TEMPS FOR THE PERIOD. IN GENERAL...EXPECT HIGH TEMPS SLIGHTLY ABOVE NORMAL SATURDAY AND... BASED ON THE GFS FRONTAL POSITIONING...SLIGHTLY BELOW NORMAL ON SUNDAY. OVERNIGHT LOWS GENERALLY IN THE LOW TO MID 40S. GFS FORECAST SOUNDINGS INDICATE MOISTURE INCREASING FROM THE TOP DOWN STARTING SATURDAY...SATURATING THROUGHOUT THE COLUMN FROM NORTH TO SOUTH BY SUNDAY NIGHT. GIVEN THE CURRENT MODEL DIFFERENCES AND DEGREE OF UNCERTAINTY...WILL CONTINUE TO LEAN TOWARD THE MORE CONSISTENT GFS SOLUTION...WITH SLIGHT CHANCE OF RAIN ACROSS THE NORTH BEGINNING SATURDAY AFTERNOON...EXTENDING ACROSS THE ENTIRE AREA BY SUNDAY. MONDAY THROUGH TUESDAY: THE MODELS AGREE THAT A STRONG LOW PRESSURE SYSTEM WILL DEVELOP IN THE LEE OF THE ROCKIES SUNDAY NIGHT AND DEEPEN AS IT MOVES EAST AND NORTHEAST THROUGH THE GREAT LAKES TOWARD THE END OF THE PERIOD. AT THE SURFACE...THE LOW AND ASSOCIATED COLD FRONT WILL PUSH THE HIGH OUT OF THE NE AND BRING THE CHANCE FOR ANOTHER ROUND OF PRECIP THROUGH THE AREA. THERE IS SOME INDICATION IN THE MODELS OF A PERIOD OF LIGHT PRECIP ACROSS THE WEST AHEAD OF THE MAIN SYSTEM...LIKELY THE PRODUCT OF SOME ISENTROPIC LIFT AS THE ENE RETURN FLOW ADVECTS LOW LEVEL MOISTURE INTO THE AREA. MODELS ARE TRENDING DRIER WITH THE FROPA TUESDAY...AS WESTERLY FLOW OFF THE APPALACHIANS INDUCES SUBSIDENCE. WITH SOME UNCERTAINTY WITH REGARD TO LOCATION OF THE PARENT LOW AND TIMING OF THE FROPA...WILL CARRY SLIGHT CHANCE OF RAIN INTO TUESDAY...WITH GFS FORECAST SOUNDINGS INDICATING DRYING BEHIND IT. HIGH TEMPS MONDAY AND TUESDAY IN THE UPPER 50S NORTH TO MID 60S SOUTH. LOW TEMPS MONDAY NIGHT IN THE MID TO UPPER 40S... DECREASING TUESDAY NIGHT BEHIND THE FRONT...MID 30S NORTHWEST TO LOW 40S SOUTHEAST. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 115 AM WEDNESDAY... 24-HR TAF PERIOD: VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD IN ASSOCIATION WITH A DRY AIRMASS IN PLACE OVER THE REGION. NORTHWEST WINDS AT 5-10 KT WILL PREVAIL THROUGH 12Z THIS MORNING. WINDS WILL BACK TO A MORE WESTERLY DIRECTION AND INCREASE TO ~15 KT SUSTAINED WITH GUSTS UP TO ~25 KT BY 15-18Z. WINDS WILL VEER TO THE NORTHWEST AT 10-15 KT WITH GUSTS UP TO 20 KT BY 00Z THIS EVENING...WITH GUSTS BECOMING MORE SPORADIC IN NATURE OVERNIGHT. LOOKING AHEAD: VFR CONDITIONS AND A NORTHWEST BREEZE WILL PERSIST ON THURSDAY. A FAST MOVING CLIPPER LOW WILL TRACK SOUTHEAST THROUGH THE CAROLINAS THURSDAY NIGHT AND EARLY FRIDAY MORNING...HOWEVER...AT THIS TIME ANTICIPATE THAT CEILINGS WILL REMAIN AT OR ABOVE 4-5 KFT AGL. VFR CONDITIONS WILL PERSIST THROUGH FRIDAY NIGHT...WITH THE NEXT CHANCE OF SUB-VFR CONDITIONS ON SAT/SUN IN ASSOCIATION WITH A COLD FRONT EXPECTED TO MOVE INTO THE REGION FROM THE NORTH. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...HARTFIELD/CBL SHORT TERM..KRR LONG TERM...KC AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
118 AM EDT WED MAR 13 2013 .SYNOPSIS... HIGH PRESSURE WILL BUILD TOWARD THE REGION FROM THE WEST TODAY THROUGH THURSDAY. A CLIPPER LOW WILL TRACK RAPIDLY SOUTHEAST INTO THE MID ATLANTIC AND CAROLINAS THURSDAY NIGHT. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... AS OF 930 PM TUESDAY... THROUGH TONIGHT: SKIES HAVE CLEARED ACROSS ALL OF CENTRAL NC AS THE COLD FRONT WHICH BROUGHT TODAY`S RAIN HAS SHIFTED TO COASTAL SECTIONS AND IS POISED TO MOVE OFFSHORE... PROPELLED BY COOL HIGH PRESSURE EXTENDING FROM CENTRAL CANADA DOWN THROUGH THE PLAINS AND LOWER MISS VALLEY. THE DIFFERENCE BETWEEN THE 00Z SOUNDINGS AT MHX (SOME LINGERING MOISTURE BELOW 850 MB) AND GSO (VERY DRY AIR THROUGH THE COLUMN) TELLS THE STORY... AS DOES THE WATER VAPOR IMAGERY SHOWING WELL THE SLUG OF DRY AIR SWEEPING TO THE NE THROUGH CENTRAL NC. UPPER LEVEL TRAJECTORIES DO SUGGEST HOWEVER THAT THE HIGH CLOUDS NOW STREAMING ACROSS ARK AND THE MEMPHIS AREA WILL SWEEP ACROSS NC TOWARD MIDNIGHT AND DURING THE OVERNIGHT HOURS... ALSO INDICATED BY THE RAP SOUNDINGS. WILL INCLUDE A THIN VEIL OF CLOUDS OVERNIGHT... BUT OTHERWISE SKIES SHOULD BE CLEAR. AS THE SURFACE RIDGE BUILDS IN OVERNIGHT WITH NORTHEASTERLY SURFACE WINDS AND COLD AIR ADVECTION... THICKNESSES ARE EXPECTED TO PLUMMET... FROM MUCH ABOVE NORMAL READINGS TODAY TO JUST BELOW NORMAL READINGS BY MORNING... ALTHOUGH THE MORE SIGNIFICANT DROP COMES WEDNESDAY INTO WEDNESDAY NIGHT WITH THE ARRIVAL OF THE POLAR FRONT. BOTH TEMPS AND DEW POINTS ARE TRENDING VERY CLOSE TO THE FORECAST PACE... AND LOWS OF 34-42 STILL LOOK REASONABLE. -GIH WEDNESDAY AND WEDNESDAY NIGHT: POTENT SHORTWAVE ENERGY UPSTREAM OVER MINNESOTA WILL DIG SOUTHEAST INTO THE TN VALLEY TONIGHT AND THEN THROUGH THE CAROLINAS AND VIRGINIA ON WEDNESDAY. AS THE POTENT VORTMAX SWINGS THROUGH THE AREA...STRONG DCVA AIDED BY COOLING ALOFT WILL RESULT IN STRONG MID AND UPPER LEVEL ASCENT. AIRMASS WILL BE TOO DRY TO SUPPORT OTHER THAN A PERIOD OF A PERIOD OF BROKEN TO OVERCAST MID CLOUDS WEDNESDAY AFTERNOON. AN ATYPICALLY COLD AIRMASS ALOFT (H85 TEMPS 1-2 STD DEVIATIONS BELOW NORMAL)IN THE PRESENCE OF DEEP VERTICAL MIXING WILL RESULT IN BELOW NORMAL TEMPERATURES WITH BREEZY NWLY WIND GUSTS BETWEEN 20 TO 25KTS. BOTH THE DRY-ADIABATIC AND LOW-LEVEL THICKNESS TEMPERATURES SCHEME SUGGEST AFTERNOON HIGHS A GOOD 5 TO 8 DEGREES BELOW STATISTICAL MOS GUIDANCE. HOWEVER...CONSIDERING THE EVER INCREASING SUN ANGLE THIS TIME OF YEAR...AM CONCERNED CURRENT FORECAST MAY BE A TOUCH TOO COOL...BUT THE EXPECTED PERIOD OF BROKEN MID-LEVEL CLOUD COVER SHOULD HELP. HIGHS NEAR 50 NW TO MID/UPPER 50S SOUTHEAST. A SECONDARY ROUND OF LOW-LEVEL COLD ADVECTION WILL OCCUR WEDNESDAY EVENING/NIGHT IN ASSOCIATION WITH RENEWED LOW-LEVEL NWLY FLOW IN THE WAKE OF THE EXITING UPPER LEVEL TROUGH. MINS FOR THE SECOND CONSECUTIVE NIGHT WILL BE DRIVEN BY CAA. LOWS WED NIGHT IN THE UPPER 20S TO LOWER 30S. -CBL && .SHORT TERM /THURSDAY THROUGH FRIDAY/... AS OF 320 PM TUESDAY... A STRONG UPPER LEVEL TROUGH WILL STILL BE IN PLACE ALONG THE EASTERN US ON THURSDAY. THIS...ALONG WITH CONTINUED COLD AIR ADVECTION (NORTHWESTERLY WINDS OF 10-15 MPH WILL LEAD TO ANOTHER DAY OF BELOW NORMAL TEMPS. HIGHS ARE ONLY EXPECTED TO BE IN THE LOW 50S (POSSIBLY STRUGGLING TO EVEN REACH 50 DEGREES IN SOME LOCATIONS). THE UPPER LEVEL TROUGH AXIS WILL MOVE OFFSHORE THURSDAY NIGHT...BUT A DISTURBANCE WITHIN THE NORTHWEST FLOW ALOFT WILL MOVE SOUTHEASTWARD ACROSS THE REGION THURSDAY NIGHT INTO FRIDAY MORNING. IT STILL APPEARS THE MAIN IMPACT FROM THIS FEATURE WILL BE AN INCREASE IN MID LEVEL CLOUD COVER AS THE BOUNDARY LAYER IS PROGGED TO BE RATHER DRY. HOWEVER...CANNOT COMPLETELY SOME SPRINKLES OR A LIGHT SHOWER... ESPECIALLY ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. DESPITE CLOUD COVER...OVERNIGHT LOWS WILL GENERALLY BE WITHIN A DEGREE OR TWO OF FREEZING. CLOUDS WILL DECREASE THROUGHOUT THE DAY ON FRIDAY AS SUBSIDENCE INCREASES ON THE BACKSIDE OF THE DEPARTING SHORTWAVE. AS HEIGHTS INCREASE SOME...TEMPS WILL BEGIN TO MODERATE...WITH HIGHS IN THE MID/UPPER 50S AND OVERNIGHT LOWS IN THE MID/UPPER 30S EXPECTED. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 320 PM TUESDAY... UNCERTAINTY REMAINS HIGH DURING THE LONG TERM PERIOD. OVERALL...THE FLOW ALOFT IS PROGGED TO DEAMPLIFY AND TEMPS SHOULD GRADUALLY MODIFY THROUGH THE WEEKEND. MODELS ARE STILL INDICATING A BACKDOOR FRONT MOVING INTO THE AREA ON SATURDAY...BUT THERE IS CONSIDERABLE DISAGREEMENT ON HOW TO HANDLE THIS FRONT. THE LAST COUPLE OF RUNS OF THE GFS PUSH THE FRONT SOUTH OF THE AREA SATURDAY NIGHT...WHILE THE ECMWF STALLS THE FRONT SOMEWHERE NEAR THE FORECAST AREA. THIS CREATES A LOT OF DISAGREEMENT WITH RESPECT TO BOTH PRECIP CHANCES AND TEMPS. THEN MODELS SHOW A WAVE OF LOW PRESSURE DEVELOPING ON THE FRONT SUNDAY INTO MONDAY AND TRACKING EAST...ALTHOUGH WHERE EXACTLY THIS FRONT WILL BE (AND ASSOCIATED LOW TRACK) IS STILL IN QUESTION. MODELS ARE THEN IN GENERAL AGREEMENT WITH A MORE AMPLIFIED TROUGH ALOFT MOVING INTO THE MIDWEST ON TUESDAY...WITH AN ASSOCIATED SURFACE FRONT PROGGED TO CROSS THE REGION TUESDAY/TUESDAY NIGHT. GIVEN ALL THE UNCERTAINTY WILL NOT CHANGE THE FORECAST TOO MUCH...WITH SLIGHT CHANCE POPS OVER THE WEEKEND...BEFORE SLIGHTLY HIGHER POPS FOR EARLY NEXT WEEK. TEMPS ARE EXPECTED TO BE ABOVE NORMAL ON SATURDAY (AHEAD OF THE BACKDOOR FRONT)...WITH NEAR NORMAL TEMPS FOR THE REMAINDER OF THE PERIOD (ALTHOUGH IT WILL BE HIGHLY DEPENDENT ON FRONTAL POSITION). && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 115 AM WEDNESDAY... 24-HR TAF PERIOD: VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD IN ASSOCIATION WITH A DRY AIRMASS IN PLACE OVER THE REGION. NORTHWEST WINDS AT 5-10 KT WILL PREVAIL THROUGH 12Z THIS MORNING. WINDS WILL BACK TO A MORE WESTERLY DIRECTION AND INCREASE TO ~15 KT SUSTAINED WITH GUSTS UP TO ~25 KT BY 15-18Z. WINDS WILL VEER TO THE NORTHWEST AT 10-15 KT WITH GUSTS UP TO 20 KT BY 00Z THIS EVENING...WITH GUSTS BECOMING MORE SPORADIC IN NATURE OVERNIGHT. LOOKING AHEAD: VFR CONDITIONS AND A NORTHWEST BREEZE WILL PERSIST ON THURSDAY. A FAST MOVING CLIPPER LOW WILL TRACK SOUTHEAST THROUGH THE CAROLINAS THURSDAY NIGHT AND EARLY FRIDAY MORNING...HOWEVER...AT THIS TIME ANTICIPATE THAT CEILINGS WILL REMAIN AT OR ABOVE 4-5 KFT AGL. VFR CONDITIONS WILL PERSIST THROUGH FRIDAY NIGHT...WITH THE NEXT CHANCE OF SUB-VFR CONDITIONS ON SAT/SUN IN ASSOCIATION WITH A COLD FRONT EXPECTED TO MOVE INTO THE REGION FROM THE NORTH. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...HARTFIELD/CBL SHORT TERM..KRR LONG TERM...KRR AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS BISMARCK ND
404 AM CDT WED MAR 13 2013 .SHORT TERM...TODAY THROUGH THURSDAY... THE MAIN HIGHLIGHT OF THE SHORT TERM PERIOD IS PRECIPITATION CHANCES THIS MORNING AND AGAIN TONIGHT. CURRENTLY...LATEST RADAR REFLECTIVITIES AT 0830Z SHOW SCATTERED SNOW SHOWERS OVER EASTERN MONTANA THROUGH NORTHWEST SOUTH DAKOTA ASSOCIATED WITH AN EASTWARD MOVING WARM FRONT. ACROSS THE WEST...SURFACE OBSERVATIONS OVER THE LAST COUPLE OF HOURS HAVE YET TO REFLECT ANY SNOW REACHING THE SURFACE. THE 00Z SUITE OF DETERMINISTIC MODELS ARE IN DISAGREEMENT REGARDING PRECIP AND QPF. THE 00Z ECWMF/GFS PAINT LIGHT QPF OVER THE WEST OVER THE NEXT FEW HOURS...WHILE THE NAM/GEM KEEP THE WEST DRY. THE 07Z RAP HAS THE AREA OF SNOW SHOWERS CONTINUING TO MOVE EAST...BUT THEN STALL AND DIMINISH ACROSS THE WEST LATER THIS MORNING. FOR NEAR TERM POPS...HAVE USED A BLEND OF THE GFS/ECWMF/RAP. SNOW ACCUMULATIONS ARE EXPECTED TO BE UNDER A HALF INCH. THE AFOREMENTIONED WARM FRONT WILL CONTINUE TO PUSH EAST AND OVER NORTH DAKOTA TODAY. WITH WARM AIR ADVECTION TAKING PLACE OVER THE AREA...THERE WILL BE SHARP TEMPERATURE GRADIENT DEVELOPING. WHERE RECENT SNOW HAS FALLEN AND IS STILL IN PLACE...TEMPERATURES WILL REMAIN SEASONABLE AND IN THE UPPER 20S AND LOWER 30S. THE GREATEST WARM UP WILL BE FOR THE SNOWLESS SOUTHWEST...WHERE TEMPERATURES WILL WARM INTO THE MID TO UPPER 50S. FOR TONIGHT...A WEAK UPPER LEVEL IMPULSE WILL MOVE ACROSS THE AREA...BRINGING A PERIOD OF LIGHT PRECIPITATION THROUGH FRIDAY MORNING. THERE IS DISAGREEMENT BETWEEN THE 00Z MODEL SOLUTIONS...WITH THE NAM/GEM KEEPING PRECIP FURTHER EAST...THE ECWMF BEING MORE PROGRESSIVE...AND THE GFS BRINGING LIGHT QPF TO THE AREA. HAVE UTILIZED A BLEND OF THE 00Z GFS/ECWMF SOLUTIONS. PRECIPITATION WILL BE IN THE FORM LIGHT RAIN FOR LOCATIONS ALONG THE MISSOURI...AS THE THERMAL PROFILE WILL BE ABOVE FREEZING...AND AS LIGHT WINTRY MIX ACROSS THE NORTH. ANY ACCUMULATING SNOW WILL BE CONFINED TO THE TURTLE MOUNTAINS AND FAR EAST...WHERE OVERNIGHT TEMPERATURES WILL COOL INTO THE UPPER 20S. FOR THURSDAY...A DRY AND MILD DAY IS EXPECTED. THURSDAY AFTERNOON HIGHS WILL BE 10 TO 15 DEGREES WARMER THAN NORMAL FOR THE SOUTHWEST AND SOUTH CENTRAL...WHERE TEMPERATURES WILL CLIMB INTO THE MID TO UPPER 50S. FOR THE FAR SOUTHWEST...LOWER 60S ARE A POSSIBILITY. ELSEWHERE...TEMPERATURES WILL BE IN THE 30S AND 40S. .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... FRONTOGENESIS ALONG A BAROCLINIC ZONE OVER NORTHWESTERN NORTH DAKOTA IS PROGGED TO EXTEND INTO SOUTHEASTERN NORTH DAKOTA THURSDAY NIGHT. THIS WILL GENERATE CATEGORICAL PRECIP CHANCES NORTH WITH CHANCE POPS CENTRAL...MAINLY AFTER MIDNIGHT. THE LATEST 00Z MODEL SUITE IS A LITTLE FASTER THAN PREVIOUS RUNS AND PROGS THE BOUNDARY TO PUSH SOUTH ACROSS THE STATE FRIDAY MORNING AND INTO SOUTH DAKOTA FRIDAY AFTERNOON. SUBSEQUENTLY...THE PRECIP TYPE IS PROGGED TO TRANSITION FROM A WINTRY MIX CENTRAL EARLY FRIDAY MORNING TO ALL SNOW BY MID TO LATE FRIDAY MORNING. MADE ADJUSTMENTS TO THE HOURLY WX GRIDS ACCORDINGLY. THE SNOW CHANCES SHOULD TAPER OFF FROM WEST TO EAST FRIDAY NIGHT AS HIGH PRESSURE BUILDS INTO THE REGION. A WEAK WAVE IN WESTERLY FLOW ALOFT IS PROGGED TO GENERATE A SLIGHT CHANCE OF SNOW SATURDAY AND SATURDAY NIGHT. HOWEVER...ACCUMULATIONS SHOULD BE LIGHT. A MORE POTENT SHORTWAVE IS THEN PROGGED TO AFFECT THE NORTHERN PLAINS SUNDAY/SUNDAY NIGHT/MONDAY. THE 00Z ECMWF CONTINUES TO BE MORE AGGRESSIVE THAN THE GFS/GEM WITH RESPECT TO THE STRENGTH OF THIS FEATURE. HOWEVER...THE ECMWF IS TRENDING FARTHER SOUTH WITH ITS TRACK. GIVEN THE MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...WENT WITH A BLEND OF SOLUTIONS AND INCREASED POPS SUNDAY THROUGH MONDAY. HIGH PRESSURE BUILDING INTO THE REGION SHOULD GENERATE COOL AND DRY CONDITIONS TUESDAY WITH BELOW NORMAL TEMPERATURES EXPECTED. && .AVIATION... VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE TAF PERIOD. THERE IS A POTENTIAL FOR LOW VFR CONDITIONS IN STRATUS AND SNOW AFTER 09 UTC ACROSS NORTHWEST NORTH DAKOTA...POSSIBLY IMPACTING KISN BETWEEN 09 UTC AND 12 UTC. FURTHERMORE...THERE WILL BE A SLIGHT CHANCE FOR A RAIN/SNOW MIX NORTH (KISN/KMOT) LATE THIS AFTERNOON. HOWEVER...CONDITIONS SHOULD REMAIN VFR. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...LTH LONG TERM/AVIATION...TM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
650 AM EDT WED MAR 13 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 447 AM EDT WED MAR 13 2013 WV IMAGERY AND RUC ANALYSIS UPPER TROUGH IS STILL ROTATING OVER THE GREAT LAKES REGION THIS MORNING. THE ABUNDANT MOISTURE WITH THIS UPPER LOW AND 850MB TEMPERATURES AROUND -16C LED TO MODERATE TO HEAVY LAKE EFFECT SNOW OFF LAKE SUPERIOR YESTERDAY INTO THE OVERNIGHT HOURS. AS OF 2AM...THE SNOWFALL TOTAL AT OUR OFFICE HAD REACHED 8.7 INCHES. BUT MID LEVEL DRYING...SEEN ON THE 00Z KINL AND CWPL SOUNDINGS ALONG WITH IR SATELLITE OVER WESTERN LAKE SUPERIOR...HAD BROUGHT A QUICK END TO THE SNOW OVER THE WESTERN CWA SHORTLY AFTER MIDNIGHT AND RECENT RADAR TRENDS OVER THE CENTRAL AND EAST SHOW SIMILAR QUICK DECREASE. UPPER RIDGE AND SURFACE HIGH PRESSURE WILL BE BUILDING IN TODAY AND REMAINING INTO TONIGHT. THIS WILL CONTINUE TO PULL THE DRY AIR OVER THE AREA AND SHOULD BRING AN END TO THE LINGERING SNOW SHOWERS OVER THE EAST DURING THE MORNING HOURS. WITH THE QUICK DECREASE TO THE SNOW...DECIDED TO DROP THE REMAINING WINTER WX ADVISORIES OVER THE EAST. THE GUSTY WINDS TODAY WILL KEEP SOME BLOWING SNOW IN THE FORECAST...WITH THE BEST CHANCES NEAR LAKE SUPERIOR EAST OF MARQUETTE. BASED ON LATEST TRENDS...HAVE OPTED TO GO MORE A LITTLE MORE OPTIMISTIC ON THE CLOUD COVER FOR TODAY. THE QUICK TRANSITION TO VFR AND MID CLOUDS OVER THE WEST SHOWS A LACK OF LOW LEVEL MOISTURE EVENTHOUGH 850MB TEMPS ARE STILL AROUND -14C. THERE IS JUST ENOUGH TERRAIN ENHANCEMENT TO AID CLOUD COVER OVER THE WEST AND THAT COULD BE THE CASE TODAY...ESPECIALLY WITH SOME DIURNAL HEATING HELP. THUS...AFTER THE DEEPER MOISTURE DEPARTS THIS MORNING...TRANSITIONED TO A PARTLY CLOUDY SKY WITH THE GREATEST CLEARING NEAR THE WISCONSIN BORDER. HIGHS TODAY WILL REMAIN BELOW NORMAL WITH MOST LOCATIONS IN THE MID-UPPER 20S. FOR TONIGHT...MODELS STILL HINTING AT A INCREASE IN THE MOISTURE IN THE 925-875MB RANGE LATE THIS AFTERNOON INTO THIS EVENING FROM THE KEWEENAW SOUTHEAST THROUGH MARQUETTE/ALGER COUNTIES. 875MB TEMPS AROUND -12.5C WOULD SUPPORT ENOUGH INSTABILITY FOR SOME SNOW SHOWERS...BUT CONCERN IS THE DEPTH OF THE CLOUD LAYER WHICH WILL LIKELY ONLY BE 2-3KFT. THERE WAS A THIN AREA OF CLOUDS THIS PAST EVENING WHERE THE MODELS ARE SHOWING THE LOW MOISTURE...BUT IT HAS SINCE DISSIPATED. THAT MOISTURE MAY STILL BE PRESENT AND WITH THE INFLUENCE OF LAKE SUPERIOR...PUT IN A MENTION OF ISOLATED FLURRIES FOR ALGER/LUCE/SCHOOLCRAFT COUNTIES. OTHERWISE...HIGH PRESSURE SHOULD BE IN PLACE OVER THE AREA AND LEAD TO A QUIET NIGHT. THE WESTERN CWA WILL LIKELY BE MOSTLY CLEAR DURING THE EVENING HOURS BEFORE MID/HIGH CLOUDS START STREAMING IN AHEAD OF THE NEXT SHORTWAVE DROPPING THROUGH THE NORTHWEST FLOW ALOFT. THINKING THE HIGH CLOUDS WILL BE IN BY MIDNIGHT AND THEN THEY WILL THICKEN/LOWER THROUGH THE NIGHT AND COVER ALL OF THE WESTERN CWA BY MORNING. THIS GIVES CONCERN TO LOWS FOR TONIGHT...AS THE CLOUD COVER WILL HAVE A GREAT INFLUENCE ON TEMPERATURES WITH THE OTHERWISE GOOD RADIATIONALLY COOLING NIGHT WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF NORMAL. THE REGIONAL GEM...WHICH USUALLY DOES WELL IN THESE RADIATIONAL AND CLOUD SITUATIONS HAS LOWS AROUND ZERO AROUND IRON COUNTY AND THAT COMBINED WITH THE PREVIOUS FORECAST SEEMS LIKE THE WAY TO GO. UNFORTUNATELY IN THESE SITUATIONS...AN HOUR OR TWO DIFFERENCE IN CLOUD COVER TIMING CAN EASILY BUST THE FORECAST IN EITHER DIRECTION. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 447 AM EDT WED MAR 13 2013 UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE OVER THE WESTERN U.S. WITH A TROUGH OVER THE EASTERN U.S. 12Z THU. THE RIDGE GETS FLATTENED WITH TIME ON FRI WITH A SHORTWAVE MOVING INTO THE NORTHERN PLAINS LATE FRI. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE AND DEEPER MOISTURE MOVING IN ON FRI AND FRI NIGHT. FOR THIS FORECAST...NOT REAL CONFIDENT IN THE STORM SYSTEM FOR FRIDAY FOR NOW. ECMWF AND GFS ARE TAKING THE SYSTEM A BIT FURTHER SOUTH WHILE THE NAM IS NORTH WITH IT. NO REAL CONTINUITY IN THE MODELS EITHER WITH THEIR FORECASTS...SO CONFIDENCE IS FAIRLY LOW. WITH THE DIFFERENCE IN PLACEMENT OF THE SYSTEM...THIS WILL AFFECT HOW COLD 850 MB TEMPERATURES ARE. 12Z ECMWF WAS MUCH WARMER AT 850 MB WITH TEMPERATURES OF -4C TO -8C ON FRI. 00Z ECMWF NOW IS COLDER WITH 850 MB TEMPERATURES -8C TO -14C WHILE THE GFS IS -10C TO -12C. WITH NORTH WINDS AND DELTA-T GREATER THAN 11C...THIS IS ENOUGH FOR LAKE ENHANCEMENT OF THE SNOW. COULD SEE UP TO 5 INCHES OF SNOW ON FRIDAY INTO FRIDAY NIGHT AND WILL PROBABLY NEED SOME HEADLINES UP FOR FRIDAY AND FRIDAY NIGHT. WENT LIKELY POPS ON FRIDAY FOR THE LAKE ENHANCEMENT. FOR THU...LOOKS LIKE A SYSTEM WILL STAY TO THE WEST OF THE AREA AND ENDED UP GOING DRIER FOR THE FORECAST AS 850 MB TEMPERATURES ARE NOT COLD ENOUGH FOR LAKE ENHANCEMENT. OVERALL...LOWERED HIGH TEMPERATURES A COUPLE DEGREES ALONG WITH OVERNIGHT LOWS DUE TO TRENDS LATELY WHERE FORECASTS HAVE BEEN TOO WARM. IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE NORTHERN U.S. 12Z SAT. THIS TROUGH REMAINS OVER THE AREA ON SUN. A TROUGH DIGS IN THE NORTHERN PLAINS ON MON AND AFFECTS THE UPPER GREAT LAKES MON NIGHT INTO TUE. TEMPERATURES CONTINUE TO LOOK COLDER THAN NORMAL THROUGH THE PERIOD WITH NO WARM UP IN SIGHT. WITH COLD TEMPERATURES IN PLACE...LAKE EFFECT SNOW WILL BE POSSIBLE THIS EXTENDED PERIOD FOR SAT AND SUNDAY. ANOTHER SYSTEM ARRIVES FOR MON INTO TUE AND BRINGS A CHANCE FOR SNOW. THIS SYSTEM WILL HAVE TO BE WATCHED AS COULD BE ANOTHER SIGNIFICANT WINTER STORM AND WILL HIT UP THIS POTENTIAL IN THE HWO PRODUCT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 649 AM EDT WED MAR 13 2013 SYSTEM THAT HAS BROUGHT THE SNOW TO THE AREA OVER THE LAST COUPLE OF DAYS AS STARTED TO EXIT AND DRIER AIR HAS SURGED SOUTH ACROSS LAKE SUPERIOR. THIS SHOULD LEAD TO VFR CONDITIONS FOR MUCH OF THE FORECAST PERIOD. THERE ARE A COUPLE ITEMS TO NOTE THOUGH. FIRST...THERE WILL STILL BE GUSTY WINDS THROUGH THE EARLY AFTERNOON...ESPECIALLY AT KSAW. THIS COULD PRODUCE A SOME BLOWING SNOW...BUT LEFT VISIBILITY RESTRICTIONS OUT OF THE TAF. SECOND...MODELS ARE SHOWING A POCKET OF LOWER LEVEL MOISTURE MOVING SOUTHEAST ACROSS LAKE SUPERIOR LATE THIS AFTERNOON AND INTO THE EVENING HOURS. CONFIDENCE IS LIMITED ON THIS OCCURRING WITH THE LACK OF CLOUDS UPSTREAM...BUT DID PUT A MENTION OF BORDERLINE MVFR CEILINGS FOR KCMX/KSAW. FINALLY...A SHORTWAVE WILL BE MOVING THROUGH WISCONSIN TOMORROW...WHICH WILL SPREAD MID CLOUDS OVER THE AREA AND COULD BRUSH KIWD WITH -SHSN AT THE END OR JUST AFTER THE TAF PERIOD. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 447 AM EDT WED MAR 13 2013 A SURFACE TROUGH THAT DROPPED SOUTH ACROSS LAKE SUPERIOR LAST NIGHT WILL CONTINUE TO PRODUCE NORTHWEST WINDS OF 20-30KTS OVER THE EASTERN LAKE TODAY. BUT WITH THE PARENT LOW MOVING NORTHEAST THROUGH QUEBEC...THIS TIGHT PRESSURE GRADIENT WILL WEAKEN THIS AFTERNOON AS HIGH PRESSURE MOVES OVER THE LAKE TONIGHT. WINDS HAVE DROPPED BELOW GALES AT OBSERVATION SITES AND HAVE DROPPED THE GALE WARNING. THERE COULD STILL BE A FEW GALE FORCE GUSTS OVER THE EASTERN LAKE DURING THE MORNING...BUT THE COVERAGE SHOULD BE LIMITED. TONIGHT/S HIGH WILL BEGIN TO SHIFT EAST ON THURSDAY...ALLOWING A COLD FRONT TO DROP SOUTHEAST ACROSS LAKE SUPERIOR ON THURSDAY NIGHT. A SECONDARY LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST FROM THE UPPER MISSISSIPPI VALLEY TO THE LOWER GREAT LAKES ON FRIDAY INTO FRIDAY NIGHT...SHIFTING WINDS TO A NORTHERLY DIRECTION AT 15-30KTS. BEHIND THIS LOW...A LARGE AREA OF HIGH PRESSURE WILL MOVE INTO THE UPPER GREAT LAKES FOR SATURDAY. ANOTHER WEAK TROUGH WILL MOVE ACROSS LAKE SUPERIOR ON SATURDAY NIGHT BEFORE THE HIGH PRESSURE RIDGE RESETS OVER THE UPPER GREAT LAKES. THERE WILL BE FREEZING SPRAY OVER CENTRAL AND EASTERN LAKE SUPERIOR THROUGH THIS EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...SRF LONG TERM...07 AVIATION...SRF MARINE...SRF
AREA FORECAST DISCUSSION
NWS TOPEKA KS
555 PM CDT WED MAR 13 2013 .DISCUSSION... SEE PREV DISCUSSION. && .AVIATION... MODELS SHOW LITTLE IN THE WAY OF FORCING OR DEEP MOISTURE. THEREFORE A VFR FORECAST IS EXPECTED TO PERSISTS WITH A WEAK SFC TROUGH MOVING ACROSS THE AREA THROUGH THE DAY THURSDAY. THE RAP AND NAM SHOW THE LOW LEVEL JET INCREASING TO AROUND 40KTS OVERNIGHT SO CONTINUED WITH LLWS. WOLTERS && .PREV DISCUSSION... /314 PM CDT WED MAR 13 2013/ TONIGHT THROUGH TOMORROW...VERY LITTLE SENSIBLE WEATHER ON TAP FOR THE SHORT TERM PORTION OF THE FORECAST. ONCE BAND OF MID CLOUDS MOVE SOUTHEAST EXPECT MOSTLY CLEAR SKIES OVERNIGHT. HIGH PRESSURE CENTER WILL MOVE EAST AND WINDS WILL STRENGTHEN FROM THE SOUTH ...USHERING IN WARMER TEMPERATURES. WEAK BOUNDARY DOES MOVE THROUGH TOMORROW BY MIDDAY...WHICH ONLY SERVES TO SWITCH WINDS TO THE WEST AND CONTINUE WARMING TREND. HARDING THURSDAY NIGHT THROUGH WEDNESDAY...A NORTHWESTERLY ZONAL FLOW WILL BE IN PLACE ACROSS THE CONUS BY THE END OF THE WORK WEEK WITH A SOUTHWESTERLY SURFACE FLOW AS AN AREA OF LOW PRESSURE OVER THE NORTHERN PLAINS SINKS SOUTHWARD INTO THE CENTRAL PLAINS. WITH A MILD DAY EXPECTED ON THURSDAY...LOWS THURSDAY NIGHT WILL ONLY DROP INTO THE UPPER 30S/LOWER 40S DESPITE MOSTLY CLEAR SKIES. AS A RESULT...CAN EXPECT A MILD START TO THE DAY ON FRIDAY...WITH MODELS SHOWING 850MB TEMPERATURES SOARING UPWARDS OF 14C-16C DEGREES BY THE AFTERNOON HOURS. WITH THE SOUTHWESTERLY SURFACE FLOW INCREASING THROUGH THE DAY...COULD SEE AFTERNOON HIGHS TOPPING OUT IN THE LOW/MID 70S ACROSS FAR NORTHERN AND NORTHEAST KANSAS AND INTO THE MID/UPPER 70S ACROSS CENTRAL AND EAST CENTRAL KANSAS. MODELS SHOW THE SURFACE LOW TRACKING EASTWARD ACROSS THE FORECAST AREA BY FRIDAY AFTERNOON...WITH A COLD FRONT MOVING THROUGH THE CWA FRIDAY NIGHT AND IT LOOKS TO BE SOUTH OF THE AREA AFTER MIDNIGHT. SATURDAY AND SUNDAY...SURFACE HIGH PRESSURE WILL SPREAD SOUTHWARD ACROSS THE NORTHERN AND CENTRAL PLAINS BEHIND THE FRONT WITH TEMPERATURES EXPECTED TO DROP BACK DOWN TO JUST BELOW THE SEASONAL NORMALS AS SURFACE WINDS SHIFT TO THE NORTHEAST. MODELS CONTINUE TO SHOW A FEW WEAK WAVES DEVELOPING WITHIN THE ZONAL FLOW DURING THE SATURDAY TO SUNDAY TIMEFRAME. THERE IS STILL UNCERTAINTY AMONGST THE MODELS REGARDING THE EXACT TRACKING OF THESE WAVES AND THE BEST TIMING OF ANY LIGHT PRECIPITATION...BUT PRECIPITATION CHANCES CURRENTLY LOOK TO INCREASE BY SATURDAY NIGHT AS A BIT MORE MOISTURE MOVES INTO THE AREA. WITH TEMPERATURES DROPPING TO AROUND THE FREEZING MARK EARLY SUNDAY MORNING OVER NORTHERN AND NORTHEAST KANSAS...COULD SEE A BRIEF PERIOD OF A RAIN/SNOW MIX. HIGH TEMPERATURES SATURDAY AND SUNDAY ARE EXPECTED TO BE IN THE UPPER 40S TO LOWER 50S. SUNDAY NIGHT THROUGH MONDAY...A MORE WELL-DEFINED SHORTWAVE TROUGH WILL DEVELOP ACROSS THE NORTHERN PLAINS SUNDAY NIGHT AND PROGRESS EASTWARD TOWARD THE GREAT LAKES REGION ON MONDAY. SURFACE LOW PRESSURE ASSOCIATED WITH THIS WAVE WILL DRAG A COLD FRONT EASTWARD THROUGH THE FORECAST AREA LATE SUNDAY NIGHT INTO MONDAY MORNING...BRINGING A BETTER CHANCE FOR PRECIPITATION BEFORE EXITING EAST OF THE AREA BY MONDAY AFTERNOON. ONCE AGAIN...LOW TEMPERATURES EARLY MONDAY MORNING COULD BE NEAR THE FREEZING MARK ACROSS NORTHERN AND NORTHEAST KANSAS SO THERE MAY BE A BIT OF A RAIN/SNOW MIX BEFORE TRANSITIONING BACK OVER TO RAIN. TUESDAY AND WEDNESDAY...ONCE THIS WAVE PASSES TO THE EAST...NORTHWESTERLY ZONAL FLOW WILL RETURN TO THE CENTRAL CONUS WITH DRY CONDITIONS EXPECTED AS SURFACE HIGH PRESSURE BUILDS INTO THE NORTHERN AND CENTRAL PLAINS. TEMPERATURES LOOK TO BE BACK ON THE RISE BY WEDNESDAY WITH A RETURN OF ABOVE-NORMAL TEMPERATURES. ACH && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
423 PM EDT WED MAR 13 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 421 PM EDT WED MAR 13 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF/ CLOSED UPR LO CENTERED JUST S OF JAMES BAY MOVING STEADILY TO THE E...ALLOWING A RDG OVER THE ROCKIES TO EXPAND TO THE E...WITH 00Z-12Z H3 HGT RISES UP TO 150M EVIDENT OVER THE NRN PLAINS/UPR MS RIVER VALLEY. ALTHOUGH A STEADY NNW FLOW BTWN ASSOCIATED SFC LO OVER SE CANADA AND HI PRES RDG AXIS STRETCHING FM NW ONTARIO INTO THE CENTRAL PLAINS IS PUSHING H85 TEMPS AS LO AS -13C TO -15C INTO THE UPR LKS...THE AIRMASS IMMEDIATELY UPSTREAM IS SO DRY PER 12Z INL RAOB THAT THERE ARE NO -SHSN OR EVEN MUCH IN THE WAY OF LK CLDS OVER UPR MI ATTM. LOOKING A BIT FARTHER TO THE NW...THERE WAS SOME SC NOTED EARLIER OVER PORTIONS OF NW ONTARIO ASSOCIATED WITH A BIT MORE MSTR SHOWN ON THE 12Z YPL RAOB...BUT SUBSIDENCE ASSOCIATED WITH THE APRCHG H3 HGT RISES/SFC ACYC FLOW AS WELL AS SOME DAYTIME HEATING HAS CAUSED THIS CLD TO DISSIPATE. FARTHER TO THE NW...A SHRTWV MOVING THRU ALBERTA AND INTO SASKATCHEWAN IS ROUNDING THE UPR RDG OVER THE ROCKIES. MID/HI CLDS AHEAD OF THIS DISTURBANCE AND ASSOCIATED WARM FNT OVER THE HI PLAINS ARE PUSHING E THRU THE DAKOTAS/SCENTRAL CANADA THIS AFTN. MAIN FCST CONCERNS IN THE SHORT TERM ARE CLD TRENDS/IMPACT ON TEMPS. TNGT...ALTHOUGH LK CLDS HAVE DISSIPATED WITH ARRIVAL OF DRIER AIR/ DAYTIME HEATING WITH HIER MARCH SUN ANGLE THAT TENDS TO CAUSE SUBSIDENCE OVER LK SUP...CONCERNED SOME CLDS WL REFORM THIS EVNG WITH LOSS OF HEATING/ARRIVAL OF MSTR NOTED IN NW ONTARIO IN THE PRESENCE OF H85 TEMPS NEAR -12C AND THEN SPREAD INLAND INTO MAINLY THE NCENTRL AND ERN CWA IN NW FLOW AHEAD OF APRCHG HI PRES RDG AXIS. BUT AS THE HI PRES RDG AXIS APRCHS FM THE W...INCRSG SUBSIDENCE/MORE ACYC LLVL FLOW IS FCST TO SINK THE SUBSIDENCE INVRN LO ENUF ANY LO CLD SHOULD DSPT W-E. ALTHOUGH FCST H85 TEMPS ARE MARGINAL FOR LES... LO INVRN BASE 2-3K FT AGL WL LIMIT LES TO PERHAPS SOME FLURRIES OVER THE ERN ZNS DOWNWIND OF THE LK IN LLVL NW FLOW. PREVIOUS FCST HAD A REASONABLE HANDLE ON THESE EXPECTATIONS...SO MADE FEW CHANGES TO THESE GRIDS. SOME MID/HI CLDS WELL IN ADVANCE OF APRCHG SHRTWV/WARM FNT TO THE W ARE FCST TO MOVE INTO THE WRN ZNS LATE TNGT. BUT WITH A PERIOD OF MAINLY CLR SKIES/LGT WINDS...WL MAINTAIN MIN TEMPS FCST NEAR LO END OF GUIDANCE OVER MUCH OF THE INTERIOR W HALF. THU...SHRTWV NOW MOVING THRU SCENTRAL CANADA OVER TOP OF ROCKIES RDG IS FCST TO MOVE THRU NW ONTARIO. ALTHOUGH CLD WL OVERSPREAD UPR MI W-E AHEAD OF THE WARM FNT...PASSAGE OF SHARPER DPVA/DEEP LYR QVECTOR CNVGC TO THE N CLOSER TO TRACK OF DISTURBANCE AS WELL AS LIMITED DEPTH OF ABSOLUTE MSTR RETURN SHOULD RESULT IN A DRY DAY. H85 TEMPS ARE FCST TO RISE TO BTWN ABOUT -2C OVER THE W AND -8C OVER THE E BY 00Z FRI AS A SW FLOW DVLPS ON THE WRN FLANK OF RETREATING HI PRES... SO EXPECT A WARMER DAY ESPECIALLY OVER THE W HALF. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 421 PM EDT WED MAR 13 2013 UPPER LEVEL PATTERN STARTS OFF LONG TERM WITH ELONGATED TROUGH OVER MOST OF NORTHERN AND EASTERN CANADA AND RIDGING OVER WESTERN CANADA. OVER TIME RIDGE IS FLATTENED AS TROUGHING OVR CANADA SETTLES INTO NORTHERN TIER OF CONUS THROUGH THE UPCOMING WEEKEND. ZONAL WNW FLOW RESULTS AND WILL BRING STRONGER SHORTWAVE ACROSS NORTHERN PLAINS AND UPPER GREAT LAKES THURSDAY NIGHT AND FRIDAY. TRICKY SYSTEM WITH REGARD TO NORTHERN EXTENT OF HEAVIER SNOW. AS ALLUDED TO YDY...WILL GREATLY DEPEND ON HOW FAR SOUTH SFC-H85 BAROCLINIC ZONE ALLIGNS IN WAKE OF NORTHERN STREAM SHORTWAVE MOVING THROUGH THURSDAY NIGHT. GFS AND GEM-NH FARTHER SOUTH /12Z GFS TRENDED EVEN FARTHER SOUTH/ WHILE NAM IS MUCH FARTHER NORTH. ECMWF/UKMET A COMPROMISE...BUT THE ECMWF DID TREND FARTHER SOUTH COMPARED TO THE 12Z RUN FROM YDY/12 MARCH. SEEMS LIKE THE NAM IS BECOMING MORE OF A NORTHERN OUTLIER...SO WILL TEND TO TREND AWAY FROM THAT IDEA AND ANY MODELS THAT ARE INITIALIZED OFF OF IT SUCH AS OUR LOCAL WRF. STILL THINK THAT THE LOCATION OF TIGHTER LOW-LEVEL TEMPERATURE GRADIENT WILL BE ULTIMATELY WHERE HEAVIEST QPF/SNOW SETS UP ON FRIDAY AS SHORTWAVE AND SFC-H85 LOWS MOVE IN FROM NORTHERN PLAINS. WHERE THE TIGHT THERMAL GRADIENT OCCURS THERE IS A POTENTIAL FOR A NARROW STRIPE OF HEAVY SNOW DUE TO LOW-MID LEVEL FRONTOGENESIS AMD DIVERGENCE ALOFT FROM RIGHT ENTRANCE REGION OF JET STREAK DROPPING INTO GREAT LAKES FROM ONTARIO ALONG WITH DECENT MOISTURE ADVECTION WITH H7 MIXING RATIOS 3-4G/KG. SFC-H85 LOWS/LOW-LEVEL FLOW IS SHOWING A STRENGTHENING TREND OVERALL AS WELL. BASED ON MODEL CONSENSUS...SEEMS LIKE BETTER CHANCE FOR ENHANCEMENT/HEAVIER SNOW TO COME TOGETHER MAY END UP JUST TO OUR SOUTH. WILL KEEP POPS LIKELY TOWARD THE WEST AND SOUTH...WHERE MODEL AGREEMENT IS HIGHER THAT SNOW OCCURS. MAY NEED HEADLINES...LIKELY ADVISORIES...IN THESE AREAS FRIDAY INTO FRIDAY EVENING. WWD DAY2 GRAPHICS INDICATE SWATH OF 2-4 INCHES OF SNOW FRIDAY ALONG WI BORDER...WITH JUST A COUPLE INCHES OVER NORTHERN UPR MICHIGAN. BASED ON CROSS SECTIONS FROM GFS AND JUST THE LOOK FROM QPF FIELDS...COULD BE A VERY SHARP CUTOFF TO SNOW ON NORTH SIDE. AS AGEOSTROPIC CIRCULATION WITHIN H85-H7 FRONTOGENEIS OCCURS THERE ARE INDICATIONS THAT SUBSIDENCE AREA OVER NORTHERN UPR MICHIGAN WILL DRAW INCREASINGLY DRIER AIR IN FROM CANADA. GRADIENT OF SNOW AMOUNTS MAY END UP SIMILAR TO SNOW EVENT FROM LATE MARCH OF 2011 THAT IMPACTED FAR SOUTH CENTRAL CWA WITH OVER A FOOT OF SNOW WHILE NORTHERN CWA ONLY SAW FLURRIES. WE SHALL SEE. ONCE SNOW TAPERS OFF...DESPITE SUFFICIENT COLD AIR IN LOW-LEVELS...UNSURE ON EXTENT OF LK EFFECT GIVEN CONCERNS WITH THE DRY AIR. FAIRLY QUIET LATER FRIDAY NIGHT INTO SATURDAY MORNING. MAY SEE SOME SNOW SHOWERS FLARE UP SATURDAY AFTN INTO SATURDAY NIGHT WITH ARRIVAL OF SHORTWAVE/COLD AIR ADVECTION DRIVING H85 TEMPS DOWN TO NEAR -20C. MODELS HINT AT SHARPER LOW-LEVEL TROUGH MOVING THROUGH SATURDAY EVENING WHICH MAY ALSO ENHANCE THE SNOW. INCREASED POPS A BIT INTO SATURDAY NIGHT. GIVEN FAVORABLE LOCATION OF DGZ WITHIN MOIST LAYER PRESENT WITH LAKE EQLS UP TO 10KFT...MAY SEE SEVERAL INCHES OF FLUFFY SNOW ALONG LK SUPERIOR. INVERSION LOWERS BLO 5KFT THROUGH DAY ON SUNDAY...BUT ENOUGH COLD AIR LINGERS FOR NW FLOW AREAS TO SEE SCT LK EFFECT SNOW SHOWERS. ATTN THEN TURNS TO SHORTWAVE TROUGHING DIGGING ACROSS ROCKIES BY SUNDAY HELPING TO DEEPEN SFC LOW ON THE LEE SIDE OF THE ROCKIES. UPPER TROUGH/SFC LOW IS FORECAST TO HEAD EAST AND DEEPEN AS SHORTWAVE IN THE NORTHERN BRANCH ATTEMPTS TO PHASE WITH THE SOUTHERN STREAM SYSTEM. SFC LOW DEEPENS FURTHER AND LIFTS ACROSS GREAT LAKES WHICH MAY LEAD TO A SIGNIFICANT SNOW STORM OVER PORTIONS OF THE UPPER GREAT LAKES. UP TO 12Z THERE WAS ACTUALLY GOOD AGREEMENT FROM THE ECMWF AND GFS ON TRACK OF THE LOW. 12Z ECMWF JOGGED FARTHER WEST THOUGH IT WOULD STILL BE MAINLY A SNOW EVENT. WAVES PRODUCING THIS WEATHER SYSTEM ARE STILL WELL TO THE NORTH...UNDERSTATEMENT...OVER THE NORTHWEST TERRITORIES OF CANADA...AND IN THE VCNTY OF THE NORTH POLE. THERE IS A LOT OF INTERACTION THAT HAS TO OCCUR YET BTWN THESE WAVES...AND LIKELY OTHERS AS WELL...BEFORE A FINAL SOLUTION IS DETERMINED. CERTAINLY A SYSTEM TO WATCH THOUGH AS IT WILL HAVE GULF MOISTURE TO WORK ON. CONVECTION TO THE SOUTH TOO SO THAT INTERACTION WILL NEED TO BE ADDRESSED BY MODELS AS WELL. MID SHIFT PUT A MENTION IN HWO...WHICH SEEMS LIKE GOOD CALL IN THIS SITUATION. STRONGER SYSTEM DRAWS DOWN CONTINUAL COLD AIR ACROSS LK SUPERIOR THROUGH MIDWEEK SO PUT CHANCE POPS IN OVER NORTHERN CWA. LAST PANELS OF GFS AND ECMWF INDICATE SOME POTENTIAL FOR MODERATING TEMPS TOWARD LAST WEEK OF MARCH AS MEAN TROUGH ATTEMPTS TO SHIFT INTO EASTERN CANADA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 126 PM EDT WED MAR 13 2013 EXPECT PREDOMINANT VFR CONDITIONS AND SLOWLY DIMINISHING WINDS THIS AFTN AS HI PRES RDG AXIS/AREA OF DRIER LLVL AIR MOVES SLOWLY EWD AND PRES GRADIENT WEAKENS. NEXT CONCERN IS IMPACT OF AREA OF LLVL MSTR THAT IS PRESENT OVER NW ONTARIO. NUMERICAL GUIDANCE SHOWS THIS MOIST AIR STREAMING SEWD ACRS LK SUP AND INTO MAINLY NCENTRAL AND ERN UPR MI IN THE NW FLOW AHEAD OF THE ENCROACHING HI. CONCERNED THERE COULD BE SOME LK CLDS THAT FORM WITHIN THE CHILLY AIRMASS AFTER SUNSET ESPECIALLY AT CMX/SAW...SO RETAINED FCST OF HI END MVFR CIGS BTWN 00Z-06Z AT CMX/SAW. AS THE HI PRES RDG MOVES CLOSER...EXPECT SUBSIDENCE INVRN TO LOWER ENUF LATE TNGT TO DISSIPATE ANY MVFR CLDS THAT DO FORM. ALTHOUGH SOME MID/HI CLDS WL INVADE THE AREA ON THU... PREVAILING DRY LLVL AIR WL RESULT IN VFR CONDITIONS. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 421 PM EDT WED MAR 13 2013 AS HI PRES RIDGE AXIS MOVES IN FROM THE W TONIGHT...THE PRES GRADIENT WILL WEAKEN OVER LAKE SUP...CAUSING NNW WINDS UP TO 30 KTS LATE THIS AFTERNOON OVER THE E HALF TO DIMINISH AND FREEZING SPRAY TO END. WINDS WILL SHIFT TO THE SW ON THU AS THE RIDGE AXIS MOVES TO THE E...BUT WINDS WILL BE UNDER 20 KTS UNTIL LATE IN THE DAY OVER THE W AS ANOTHER TROF APPROACHES FROM THE NW AND SHARPENS THE PRES GRADIENT. DUE TO THAT TIGHTER PRESSURE GRADIENT...W WINDS TO 25 KTS INCREASE TO 30 KTS WHILE SHIFTING N-NW ON THU NIGHT. SLIGHT RISK THAT GALE GUSTS COULD OCCUR RIGHT IN WAKE OF THE WIND SHIFT THURSDAY EVENING OVER EASTERN LK SUPERIOR. EXPECT N-NE WINDS TO 25 KTS THROUGH FRI AS LOW PRESSURE PASSES SOUTH OF THE REGION. AFTER LIGHTER WINDS INTO SAT MORNING ANOTHER TROUGH WILL SHIFT WINDS TO NW TO 25 KTS SAT NIGHT. WINDS DIMINISH ON SUN BUT INCREASE YET AGAIN LATE ON MON AS STRONG LOW PRESSURE SYSTEM LIFTS ACROSS THE UPR LAKES REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...JLA AVIATION...KC MARINE...KC/JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
127 PM EDT WED MAR 13 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 447 AM EDT WED MAR 13 2013 WV IMAGERY AND RUC ANALYSIS UPPER TROUGH IS STILL ROTATING OVER THE GREAT LAKES REGION THIS MORNING. THE ABUNDANT MOISTURE WITH THIS UPPER LOW AND 850MB TEMPERATURES AROUND -16C LED TO MODERATE TO HEAVY LAKE EFFECT SNOW OFF LAKE SUPERIOR YESTERDAY INTO THE OVERNIGHT HOURS. AS OF 2AM...THE SNOWFALL TOTAL AT OUR OFFICE HAD REACHED 8.7 INCHES. BUT MID LEVEL DRYING...SEEN ON THE 00Z KINL AND CWPL SOUNDINGS ALONG WITH IR SATELLITE OVER WESTERN LAKE SUPERIOR...HAD BROUGHT A QUICK END TO THE SNOW OVER THE WESTERN CWA SHORTLY AFTER MIDNIGHT AND RECENT RADAR TRENDS OVER THE CENTRAL AND EAST SHOW SIMILAR QUICK DECREASE. UPPER RIDGE AND SURFACE HIGH PRESSURE WILL BE BUILDING IN TODAY AND REMAINING INTO TONIGHT. THIS WILL CONTINUE TO PULL THE DRY AIR OVER THE AREA AND SHOULD BRING AN END TO THE LINGERING SNOW SHOWERS OVER THE EAST DURING THE MORNING HOURS. WITH THE QUICK DECREASE TO THE SNOW...DECIDED TO DROP THE REMAINING WINTER WX ADVISORIES OVER THE EAST. THE GUSTY WINDS TODAY WILL KEEP SOME BLOWING SNOW IN THE FORECAST...WITH THE BEST CHANCES NEAR LAKE SUPERIOR EAST OF MARQUETTE. BASED ON LATEST TRENDS...HAVE OPTED TO GO MORE A LITTLE MORE OPTIMISTIC ON THE CLOUD COVER FOR TODAY. THE QUICK TRANSITION TO VFR AND MID CLOUDS OVER THE WEST SHOWS A LACK OF LOW LEVEL MOISTURE EVENTHOUGH 850MB TEMPS ARE STILL AROUND -14C. THERE IS JUST ENOUGH TERRAIN ENHANCEMENT TO AID CLOUD COVER OVER THE WEST AND THAT COULD BE THE CASE TODAY...ESPECIALLY WITH SOME DIURNAL HEATING HELP. THUS...AFTER THE DEEPER MOISTURE DEPARTS THIS MORNING...TRANSITIONED TO A PARTLY CLOUDY SKY WITH THE GREATEST CLEARING NEAR THE WISCONSIN BORDER. HIGHS TODAY WILL REMAIN BELOW NORMAL WITH MOST LOCATIONS IN THE MID-UPPER 20S. FOR TONIGHT...MODELS STILL HINTING AT A INCREASE IN THE MOISTURE IN THE 925-875MB RANGE LATE THIS AFTERNOON INTO THIS EVENING FROM THE KEWEENAW SOUTHEAST THROUGH MARQUETTE/ALGER COUNTIES. 875MB TEMPS AROUND -12.5C WOULD SUPPORT ENOUGH INSTABILITY FOR SOME SNOW SHOWERS...BUT CONCERN IS THE DEPTH OF THE CLOUD LAYER WHICH WILL LIKELY ONLY BE 2-3KFT. THERE WAS A THIN AREA OF CLOUDS THIS PAST EVENING WHERE THE MODELS ARE SHOWING THE LOW MOISTURE...BUT IT HAS SINCE DISSIPATED. THAT MOISTURE MAY STILL BE PRESENT AND WITH THE INFLUENCE OF LAKE SUPERIOR...PUT IN A MENTION OF ISOLATED FLURRIES FOR ALGER/LUCE/SCHOOLCRAFT COUNTIES. OTHERWISE...HIGH PRESSURE SHOULD BE IN PLACE OVER THE AREA AND LEAD TO A QUIET NIGHT. THE WESTERN CWA WILL LIKELY BE MOSTLY CLEAR DURING THE EVENING HOURS BEFORE MID/HIGH CLOUDS START STREAMING IN AHEAD OF THE NEXT SHORTWAVE DROPPING THROUGH THE NORTHWEST FLOW ALOFT. THINKING THE HIGH CLOUDS WILL BE IN BY MIDNIGHT AND THEN THEY WILL THICKEN/LOWER THROUGH THE NIGHT AND COVER ALL OF THE WESTERN CWA BY MORNING. THIS GIVES CONCERN TO LOWS FOR TONIGHT...AS THE CLOUD COVER WILL HAVE A GREAT INFLUENCE ON TEMPERATURES WITH THE OTHERWISE GOOD RADIATIONALLY COOLING NIGHT WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF NORMAL. THE REGIONAL GEM...WHICH USUALLY DOES WELL IN THESE RADIATIONAL AND CLOUD SITUATIONS HAS LOWS AROUND ZERO AROUND IRON COUNTY AND THAT COMBINED WITH THE PREVIOUS FORECAST SEEMS LIKE THE WAY TO GO. UNFORTUNATELY IN THESE SITUATIONS...AN HOUR OR TWO DIFFERENCE IN CLOUD COVER TIMING CAN EASILY BUST THE FORECAST IN EITHER DIRECTION. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 447 AM EDT WED MAR 13 2013 UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE OVER THE WESTERN U.S. WITH A TROUGH OVER THE EASTERN U.S. 12Z THU. THE RIDGE GETS FLATTENED WITH TIME ON FRI WITH A SHORTWAVE MOVING INTO THE NORTHERN PLAINS LATE FRI. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE AND DEEPER MOISTURE MOVING IN ON FRI AND FRI NIGHT. FOR THIS FORECAST...NOT REAL CONFIDENT IN THE STORM SYSTEM FOR FRIDAY FOR NOW. ECMWF AND GFS ARE TAKING THE SYSTEM A BIT FURTHER SOUTH WHILE THE NAM IS NORTH WITH IT. NO REAL CONTINUITY IN THE MODELS EITHER WITH THEIR FORECASTS...SO CONFIDENCE IS FAIRLY LOW. WITH THE DIFFERENCE IN PLACEMENT OF THE SYSTEM...THIS WILL AFFECT HOW COLD 850 MB TEMPERATURES ARE. 12Z ECMWF WAS MUCH WARMER AT 850 MB WITH TEMPERATURES OF -4C TO -8C ON FRI. 00Z ECMWF NOW IS COLDER WITH 850 MB TEMPERATURES -8C TO -14C WHILE THE GFS IS -10C TO -12C. WITH NORTH WINDS AND DELTA-T GREATER THAN 11C...THIS IS ENOUGH FOR LAKE ENHANCEMENT OF THE SNOW. COULD SEE UP TO 5 INCHES OF SNOW ON FRIDAY INTO FRIDAY NIGHT AND WILL PROBABLY NEED SOME HEADLINES UP FOR FRIDAY AND FRIDAY NIGHT. WENT LIKELY POPS ON FRIDAY FOR THE LAKE ENHANCEMENT. FOR THU...LOOKS LIKE A SYSTEM WILL STAY TO THE WEST OF THE AREA AND ENDED UP GOING DRIER FOR THE FORECAST AS 850 MB TEMPERATURES ARE NOT COLD ENOUGH FOR LAKE ENHANCEMENT. OVERALL...LOWERED HIGH TEMPERATURES A COUPLE DEGREES ALONG WITH OVERNIGHT LOWS DUE TO TRENDS LATELY WHERE FORECASTS HAVE BEEN TOO WARM. IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE NORTHERN U.S. 12Z SAT. THIS TROUGH REMAINS OVER THE AREA ON SUN. A TROUGH DIGS IN THE NORTHERN PLAINS ON MON AND AFFECTS THE UPPER GREAT LAKES MON NIGHT INTO TUE. TEMPERATURES CONTINUE TO LOOK COLDER THAN NORMAL THROUGH THE PERIOD WITH NO WARM UP IN SIGHT. WITH COLD TEMPERATURES IN PLACE...LAKE EFFECT SNOW WILL BE POSSIBLE THIS EXTENDED PERIOD FOR SAT AND SUNDAY. ANOTHER SYSTEM ARRIVES FOR MON INTO TUE AND BRINGS A CHANCE FOR SNOW. THIS SYSTEM WILL HAVE TO BE WATCHED AS COULD BE ANOTHER SIGNIFICANT WINTER STORM AND WILL HIT UP THIS POTENTIAL IN THE HWO PRODUCT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 126 PM EDT WED MAR 13 2013 EXPECT PREDOMINANT VFR CONDITIONS AND SLOWLY DIMINISHING WINDS THIS AFTN AS HI PRES RDG AXIS/AREA OF DRIER LLVL AIR MOVES SLOWLY EWD AND PRES GRADIENT WEAKENS. NEXT CONCERN IS IMPACT OF AREA OF LLVL MSTR THAT IS PRESENT OVER NW ONTARIO. NUMERICAL GUIDANCE SHOWS THIS MOIST AIR STREAMING SEWD ACRS LK SUP AND INTO MAINLY NCENTRAL AND ERN UPR MI IN THE NW FLOW AHEAD OF THE ENCROACHING HI. CONCERNED THERE COULD BE SOME LK CLDS THAT FORM WITHIN THE CHILLY AIRMASS AFTER SUNSET ESPECIALLY AT CMX/SAW...SO RETAINED FCST OF HI END MVFR CIGS BTWN 00Z-06Z AT CMX/SAW. AS THE HI PRES RDG MOVES CLOSER...EXPECT SUBSIDENCE INVRN TO LOWER ENUF LATE TNGT TO DISSIPATE ANY MVFR CLDS THAT DO FORM. ALTHOUGH SOME MID/HI CLDS WL INVADE THE AREA ON THU... PREVAILING DRY LLVL AIR WL RESULT IN VFR CONDITIONS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 447 AM EDT WED MAR 13 2013 A SURFACE TROUGH THAT DROPPED SOUTH ACROSS LAKE SUPERIOR LAST NIGHT WILL CONTINUE TO PRODUCE NORTHWEST WINDS OF 20-30KTS OVER THE EASTERN LAKE TODAY. BUT WITH THE PARENT LOW MOVING NORTHEAST THROUGH QUEBEC...THIS TIGHT PRESSURE GRADIENT WILL WEAKEN THIS AFTERNOON AS HIGH PRESSURE MOVES OVER THE LAKE TONIGHT. WINDS HAVE DROPPED BELOW GALES AT OBSERVATION SITES AND HAVE DROPPED THE GALE WARNING. THERE COULD STILL BE A FEW GALE FORCE GUSTS OVER THE EASTERN LAKE DURING THE MORNING...BUT THE COVERAGE SHOULD BE LIMITED. TONIGHT/S HIGH WILL BEGIN TO SHIFT EAST ON THURSDAY...ALLOWING A COLD FRONT TO DROP SOUTHEAST ACROSS LAKE SUPERIOR ON THURSDAY NIGHT. A SECONDARY LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST FROM THE UPPER MISSISSIPPI VALLEY TO THE LOWER GREAT LAKES ON FRIDAY INTO FRIDAY NIGHT...SHIFTING WINDS TO A NORTHERLY DIRECTION AT 15-30KTS. BEHIND THIS LOW...A LARGE AREA OF HIGH PRESSURE WILL MOVE INTO THE UPPER GREAT LAKES FOR SATURDAY. ANOTHER WEAK TROUGH WILL MOVE ACROSS LAKE SUPERIOR ON SATURDAY NIGHT BEFORE THE HIGH PRESSURE RIDGE RESETS OVER THE UPPER GREAT LAKES. THERE WILL BE FREEZING SPRAY OVER CENTRAL AND EASTERN LAKE SUPERIOR THROUGH THIS EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...SRF LONG TERM...07 AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
345 PM EDT WED MAR 13 2013 .SYNOPSIS... COLD NORTHWEST WINDS FLOWING OVER THE RELATIVELY WARM WATERS OF LAKE ONTARIO WILL BRING SNOW SHOWERS TO THE AREA TONIGHT INTO THURSDAY. A FEW INCHES OF SNOW COULD ACCUMULATE OVER OUR NORTHERN COUNTIES... WITH LESS TO THE SOUTH. HIGH PRESSURE WILL BRING DRY WEATHER THURSDAY NIGHT INTO FRIDAY... THEN THE NEXT STORM SYSTEM APPROACHING FROM THE WEST WILL BRING A CHANCE OF LIGHT SNOW OR MIXED PRECIPITATION BY LATE FRIDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY/... SNOW SHOWERS ASSOCIATED WITH A POOL OF COLD AIR ALOFT WILL MOVE ACROSS THE AREA LATE THIS AFTERNOON THROUGH MID-EVENING... WITH SNOW SHOWERS DIMINISHING AFTER SUNSET. LATEST RAP SHORT-RANGE FORECAST SOUNDINGS ARE STILL SHOWING SOME CAPE... GENERALLY 50 TO 150 J/KG ALONG WITH STEEP LOW-LEVEL LAPSE RATES. AS A RESULT SOME REPORTS OF THUNDER HAVE BEEN RECEIVED FROM THE HEAVIEST SNOW SHOWERS. WILL HAVE TO WATCH FOR SOME LOCALIZED AREAS OF SLICK TRAVEL EARLY THIS EVENING AS ANY HEAVIER SQUALL COULD BRING A QUICK COATING TO AN INCH OF SNOW ALONG WITH TEMPERATURES FALLING TO NEAR OR JUST BELOW FREEZING. SOME LAKE EFFECT SNOW BANDS WILL DEVELOP LATER THIS EVENING THROUGH THE OVERNIGHT HOURS AS LOSS OF DIURNAL HEATING ALLOWS FOR MORE ORGANIZATION OF THE RADAR ECHOES. LATEST GUIDANCE INDICATES THAT 850 MB TEMPERATURES WILL FALL ALL THE WAY TO -20 C LATE TONIGHT WHICH CERTAINLY WILL BE COLD ENOUGH FOR SOME LAKE EFFECT GIVEN ADEQUATE SYNOPTIC-SCALE MOISTURE WHICH WILL ALSO BE IN PLACE. FLOW WILL BE FROM AROUND 270 DEGREES LATE THIS EVENING WHICH WILL FAVOR ANY ORGANIZED BAND TO BE NORTH OF SYRACUSE AND THE THRUWAY. LATER TONIGHT THE FLOW SHIFTS TO BETWEEN 300 AND 310 DEGREES WHICH WILL FAVOR MULTIBANDS ACROSS A WIDE SECTION OF CENTRAL NY. AT THIS POINT EXPECTING 2 OR 3 INCHES ACROSS MUCH OF THE NORTHERN 1/3 OF THE FORECAST AREA BY THURSDAY MORNING. && .SHORT TERM /6 AM THURSDAY THROUGH SATURDAY/... SNOW SHOWERS WILL CONTINUE THURSDAY WITH A FLOW VECTOR FROM AROUND 300 DEGREES. ANOTHER COUPLE OF INCHES COULD FALL OVER THE NORTHERN 1/3 OF THE FORECAST AREA THROUGH LATE MORNING. DURING THE AFTERNOON EXPECT SNOW SHOWERS TO BECOME DISORGANIZED WITH INCREASING DIURNAL HEATING. 850 MB TEMPERATURES WILL RISE ONLY SLIGHTLY DURING THE DAY AND ENOUGH SYNOPTIC SCALE MOISTURE WILL REMAIN IN PLACE TO KEEP SOME SNOW SHOWERS GOING INTO THURSDAY EVENING. TEMPERATURES WILL LIKELY REMAIN BELOW FREEZING ACROSS THE ENTIRE AREA THROUGH THURSDAY DESPITE THE STRONG MARCH SUNSHINE. A WEAK RIDGE OF HI PRESSURE WILL BRING A PERIOD OF DRY WEATHER THURSDAY NIGHT INTO FRIDAY MORNING. LOW PRESSURE WILL TRACK ACROSS SOUTHERN CANADA ON FRIDAY... DRAGGING A FRONTAL BOUNDARY SOUTH ACROSS THE AREA DURING THE AFTERNOON. SOME MOISTURE STREAKING OUT AHEAD OF AN APPROACHING CLIPPER SYSTEM MAY TRAIN ALONG THIS FRONT FRIDAY AFTERNOON ALLOWING FOR SOME LIGHT SNOW OR A MIX OF LIGHT RAIN AND SNOW TO BREAK OUT ACROSS THE AREA DURING THE DAY. TEMPERATURES WILL RECOVER BACK ABOVE FREEZING FRIDAY AFTERNOON SO THAT ANY SNOW THAT DOES FALL WILL LIKELY NOT ACCUMULATE MUCH. CLIPPER SYSTEM PASSES SOUTH OF OUR AREA FRIDAY NIGHT INTO SATURDAY. MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE TRACK AND INTENSITY OF THIS SYSTEM... AND AS OF NOW IT LOOKS LIKE THIS SYSTEM WILL PRODUCE A PERIOD OF ACCUMULATING SNOW FRIDAY NIGHT INTO SATURDAY MORNING ACROSS AT LEAST A PORTION OF THE AREA. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A HIGHLY ACTIVE PATTERN WILL DOMINATE THE NORTHERN HEMISPHERE DURING THIS PERIOD WITH A SERIES OF FRONTAL SYSTEMS AND LOW PRESSURE SYSTEMS PASSING THROUGH...OR NEAR THE NORTHEASTERN AND MID-ATLANTIC STATES. THE INITIAL WAVE IN THE SERIES IS HANDLED DIFFERENTLY BY THE GFS AND ECMWF MODEL TRENDS. THE 13/00Z EC WOULD BRING A PERIOD OF SNOW THROUGH PA AND SOUTHERN NY DURING SUNDAY AFTERNOON AND EVENING WHILE THE 13/12Z GFS REMAINS SUPPRESSED FURTHER SOUTH. THE 13/12Z CANADIAN GGEM MODEL LEANS WITH A DRIER SOLUTION FOR THIS REGION. AT THIS TIME IT IS PRUDENT TO MENTION A CHANCE OF PRECIP EXTENDING ACROSS NEPA AND THE SOUTHERN HALF OF CNY. A MORE SUBSTANTIAL SYSTEM IS GENERALLY AGREED UPON WITHIN THE MODEL SOLUTIONS TO SLIDE THROUGH THE REGION LATER MONDAY INTO TUESDAY AS AN OCCLUDED SYSTEM. THE GFS IS A LITTLE MORE WRAPPED UP AND FURTHER N/W. THE SYSTEM GENERALLY LOOKS MILD WITH RAIN...ALTHOUGH A MIX WITH SNOW IS STILL HIGHLY POSSIBLE. THIS SYSTEM WILL ALSO USHER IN AN ANOMALOUSLY SHOT OF COLD AIR TO THE REGION FOR THE LATTER HALF OF THE WEEK. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... 18Z WED UPDATE...AN UNSTABLE ATMOSPHERE WITH A POTENT DISTURBANCE MOVING THROUGH THE REGION HAS SPAWNED NUMEROUS BANDS OF SNOW SHOWERS AND SQUALLS THIS AFTERNOON WHICH WILL CONTINUE INTO THE EARLY EVENING. IN GENERAL...VFR/MVFR CIGS WILL PREVAIL BUT VSBYS WILL BE HIGHLY VARIABLE IN AND OUT OF SQUALLS. MOST SNOW SHOWERS WILL PRODUCE IFR VSBYS...BUT THE HEAVIEST SQUALLS COULD PRODUCE NEAR WHITEOUT CONDITIONS FOR A SHORT AMOUNT OF TIME OVER THE TERMINAL. BEYOND ABOUT 00Z...SNOW SHOWERS WILL BECOME MORE SPORADIC AND BECOME FOCUSED ALONG THE DOWNWIND TRAJECTORY OF LAKE ONTARIO MAINLY AFFECTING KSYR-KRME WITH THE MOST RESTRICTIONS. ELSEWHERE... DEEPENING COLD AIR WILL KEEP CIGS IN THE MVFR CATEGORY THROUGH THURSDAY MORNING WITH SOME IMPROVEMENT TO VFR. WINDS SW 10-15 KTS INTO THIS EVENING...BECOMING W-NW AND INCREASING 15-25 KTS AND GUSTY LATER TONIGHT AND THURSDAY. .OUTLOOK... FRIDAY...MAINLY VFR BY AFTERNOON. FRIDAY NIGHT/SATURDAY EVE...RESTRICTIONS POSSIBLE IN LIGHT SNOW. SUNDAY...VFR. MONDAY...BECOMING MVFR IN A RAIN/SNOW MIX. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MSE NEAR TERM...MSE SHORT TERM...MSE LONG TERM...JAB AVIATION...JAB
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1158 AM CDT WED MAR 13 2013 .DISCUSSION...LATEST SURFACE ANALYSIS SHOWS SURFACE LOW PRESSURE IN SOUTHEAST ALBERTA WITH MAX PRESSURE FALLS IN EASTERN SASKATCHEWAN SOUTH INTO NORTH CENTRAL NORTH DAKOTA. THE LOW WILL TRACK TOWARD THE SOUTHEAST THROUGH THIS EVENING...TO NEAR BISMARCK BY 06Z THURSDAY. STRONG WARM AIR ADVECTION WITH THIS WAVE AS H85 TEMPS PER RAP MODEL ADVERTISING +8 TO +10C SOUTHEASTERN ALBERTA. THIS WILL SHIFT INTO WESTERN AND PORTIONS OF CENTRAL NORTH DAKOTA FOLLOWING THE PASSAGE OF THE SURFACE LOW LATE TONIGHT INTO THURSDAY. IN ADVANCE OF THE LOW THIS AFTERNOON...WILL CONTINUE TO MENTION AN ISOLATED MIX IN THE NORTH AS VERTICAL MOTION INCREASES IN ASSOCIATION WITH THE LEFT EXIT REGION OF A 120KT JET. THE LIGHT PRECIPITATION THREAT WILL EXPAND INTO THE JAMES RIVER VALLEY TONIGHT PER LATEST RAP/NAM/GFS. PRECIPITATION AMOUNTS ARE VERY LIGHT. ADJUSTED THE HIGHS IN THE SOUTHWEST UP A FEW DEGREES BASED ON LATEST OBSERVATIONS AND STILL PLENTY OF TIME WITH AMPLE SUNSHINE THIS AFTERNOON TO RISE. LATEST 12Z MODEL SUITE STILL ON TRACK FOR SNOW IN THE NORTH THURSDAY NIGHT AND FRIDAY. THE POTENTIAL FOR FREEZING RAIN CONTINUES TO SHRINK. THUS THE CURRENT THINKING RIGHT IS DOING A SPECIAL WEATHER STATEMENT MOST LIKELY ALONG AND NORTH OF HIGHWAY 2 FOR THURSDAY NIGHT AND FRIDAY WITH POSSIBLE ADVISORY LEVEL SNOW AMOUNTS. WILL CONTINUE TO LOOK AT THINGS...BUT THAT IS THE DIRECTION WE ARE LEANING TOWARDS AT THIS TIME. && .AVIATION...FOR THE UPCOMING 18 UTC TAF CYCLE...VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND CENTRAL NORTH DAKOTA FOR THE AFTERNOON AND INTO THE EARLY EVENING AS HIGH PRESSURE ACROSS EASTERN NORTH DAKOTA SHIFTS SLOWLY SOUTHEAST. HOWEVER...MVFR STRATUS CURRENTLY ACROSS ALBERTA AS OF 17 UTC WILL CONTINUE TO MOVE SOUTHEAST SPREADING ACROSS WESTERN AND CENTRAL NORTH DAKOTA LATE THIS EVENING AND TONIGHT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...KS AVIATION...AYD