Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 041206 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 706 AM EST WED MAR 4 2015 .SYNOPSIS... A WARM FRONT LINGERS OVER THE NORTHERN MID ATLANTIC EARLY TODAY...WITH A COLD FRONT SLOWLY CROSSING THE REGION LATER THIS AFTERNOON THROUGH TONIGHT. THE FRONT WILL STALL OVER NORTH CAROLINA ON THURSDAY...WITH A WAVE OF LOW PRESSURE MOVING ALONG THE FRONT INTO THURSDAY NIGHT. THIS WILL BRING ANOTHER ROUND OF WINTRY WEATHER TO THE AREA...FOLLOWED BY COLD AND DRY CONDITIONS BY FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... THE CURRENT SURFACE ANALYSIS SHOWS A QUASI-STATIONARY FRONTAL BOUNDARY LINGERING FROM THE TENNESSEE VALLEY THROUGH THE NRN MID- ATLANTIC WITH A RESIDUAL WEDGE AIRMASS IN PLACE TO THE LEE OF THE MOUNTAINS. THE FRONTAL BOUNDARY IS SITUATED IN BETWEEN ARCTIC HIGH PRESSURE BUILDING OVER THE CENTRAL PLAINS AND HIGH PRESSURE OFF THE COAST...AND IS ALIGNED NEARLY PARALLEL TO THE UPPER LEVEL FLOW AND HENCE IT WILL MOVE VERY LITTLE TODAY. STRATUS WILL LINGER THROUGH AT LEAST MID-MORNING...WITH AREAS OF FOG EARLY...ESPECIALLY OVER SE VA/NE NC. HIGH TEMPERATURES WILL BE VERY CHALLENGING TODAY. THERE IS A POTENTIAL THAT FAR NRN PORTIONS STAY IN THE UPPER 40S...WITH LOW 70S ACROSS SRN PORTIONS. CENTRAL PORTIONS COULD EXPERIENCE A SPREAD OF AT LEAST 10-15F DEPENDING ON THE EVENTUAL POSITION OF THE FRONTAL BOUNDARY. THE HIGHEST POPS TODAY WILL BE ACROSS THE FAR NRN TIER COUNTIES IN CLOSER PROXIMITY TO THE BOUNDARY...WITH A SHARP GRADIENT ACROSS CENTRAL PORTIONS THAT TAPERS TO 10-20% ACROSS S/SE PORTIONS. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... A COLD FRONT PRESENTLY BACK OVER THE OHIO VALLEY DROPS INTO THE AREA THIS EVENING AND TRACKS NNW-SSE ACROSS THE AREA OVERNIGHT INTO THU MORNING. MEANWHILE...A WAVE OF LOW PRESSURE DEVELOPS ALONG THE FRONT AND TRACKS ACROSS THE CAROLINAS WEDNESDAY NIGHT INTO THURSDAY. MUCH COLDER AIR ARRIVES BEHIND THE FRONT WITH MOST OF THE AREA FALLING INTO THE UPPER 20S/LOW 30S BY THU AFTN. FORECAST SOUNDINGS SHOW DRY AIR LINGERING BETWEEN 600-400MB TONIGHT...SO ANY PCPN (IN THE FORM OF -RA) WILL BE LIGHT. A STRONG ANTI-CYCLONIC JET IS PRESENTLY LOCATED FROM THE MID-MISSISSIPPI VALLEY THROUGH ATLANTIC CANADA. THIS JET STRUCTURE WILL TRANSLATE EWD THROUGH THU AS A STRONG TROUGH DIGS ACROSS THE UPPER MIDWEST AND GREAT LAKES BY LATER THU MORNING INTO THU AFTERNOON. IT IS AT THIS TIME THAT DEEPER MOISTURE WILL ARRIVE AND RRQ FORCING WILL BE IDEALIZED AND TRIGGER THE ONSET OF WINTRY PCPN FROM NW-SE ACROSS THE AREA. IT IS NOT UNTIL 21Z THU TO 00Z FRI THAT SUB 1540M 850-700MB THICKNESS VALUES ARRIVE INTO NW PORTIONS OF THE AREA. HOWEVER...BY THIS TIME THE STRONGEST UVM WILL BE EXITING THE COAST. OVERALL IT APPEARS THAT SLR VALUES WILL BE LOW (PERHAPS 5:1-8:1) GIVEN THAT THERE WILL BE A PERIOD OF SLEET...AND THAT MID-LEVEL THICKNESSES WILL BE `WARM` DURING THE STRONGEST FORCING. THE CURRENT FORECAST HAS A NARROW BAND OF 3-4" FROM LOUISA COUNTY TO DORCHESTER COUNTY BORDERED BY A BAND OF 2-3" FOR OTHER PORTIONS OF THE NW PIEDMONT...NRN NECK...AND LOWER MD EASTERN SHORE. CURRENTLY 1-2" IS FORECAST FROM THE RIC METRO DOWN THROUGH HAMPTON ROADS...WITH 1" OR LESS FARTHER S. A BRIEF PERIOD OF FZRA IS POSSIBLE DURING THE TRANSITION FROM RA TO SN/IP WITH ANY ICE ACCUM ONLY TRACE TO A FEW HUNDREDTHS OF AN INCH. CONFIDENCE IS NOT HIGH ENOUGH FOR A WATCH ACROSS THE FAR N AT THIS TIME GIVEN THAT THIS IS A LATER THIRD PERIOD EVENT...SO THIS WILL CONTINUED TO BE HIGHLIGHTED IN THE HWO. WINTRY PCPN SHOULD TAPER OFF THU EVENING...WITH DRIER AIR ARRIVING FROM THE NW DURING THE LATE EVENING. TEMPERATURES WILL CONTINUE TO PLUMMET WITH LOWS FRI MORNING RANGING FROM THE LOW TEENS NW...TO LOW 20S SE. HIGHS FRI WILL STRUGGLE TO REACH 30-35 FRI UNDER A MOSTLY SUNNY SKY. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... EXTENDED PERIOD WILL BE HIGHLIGHTED BY GENERALLY DRY CONDITIONS AND A RETURN TO NEAR SEASONABLE NORMAL TEMPS. MEDIUM RANGE GUIDANCE IN GENERAL CONSENSUS WITH THE UPPER FLOW THRU THE EXTENDED...CHARACTERIZED BY RIDGING/BLOCKING OVER THE WRN CONUS/ERN PACIFIC AND BROAD TROUGHING OVER THE CNTRL AND ERN CONUS. TO BEGIN THE PERIOD...COLD/DRY 1030+MB ARCTIC HIGH PRESSURE CENTERS OVER THE MID-ATLANTIC REGION. THURSDAYS COLD FRONT LOCATES OFF THE COAST...EXTENDING SWWD INTO THE NRN GULF. H85 TEMPS DROP TO AROUND -8C FRI (~-1 STD DEV)...SLIGHTLY WARMER THAN DEPICTED 24 HRS AGO. HIGHS FRI GENERALLY IN THE LOW-MID 30S INLAND AND UPPER 20S-LOW 30S COASTAL AREAS. AIRMASS MODIFIES FRI NIGHT-SAT AS THE COLD/DRY AIR RETREATS NWD. HIGH PRESSURE REMAINS OVER THE REGION SAT...WITH LIGHT RETURN FLOW HELPING TO MODERATE LOW LEVEL THICKNESSES. TEMPS WARM INTO THE UPPER 40S-LOW 50S INLAND AND LOW- MID 40S COASTAL AREAS. SKY AVG MOSTLY SUNNY-PARTLY CLOUDY. HIGH PRESSURE REMAINS OVER THE REGION SUN...RESULTING IN CONTINUED DRY AND WARMING CONDITIONS. HIGHS IN THE LOW-MID 50S INLAND AND LOW 40S TO UPPER 40S COASTAL AREAS. ATTENTION THEN TURNS OUT WEST...WHERE MODELS CONTINUE TO STRUGGLE HANDLING SPLIT/BLOCKY FLOW AND SRN STREAM ENERGY OVER THE DESERT SW/BAJA. GOOD NEWS IS THAT NOW THE DETERMINISTIC ECMWF HAS TRENDED DRY SUN NIGHT-EARLY NEXT WEEK...MATCHING THE GFS AND ENSEMBLES. HOWEVER...SPLIT FLOW CONTINUES RESULTING IN LOW CONFIDENCE EARLY NEXT WEEK. FRONT OVER THE GULF WILL ATTEMPT TO AMPLIFY AND LIFT NWD AS SRN STREAM ENERGY APPROACHES...BUT WILL KEEP POPS SILENT. HIGHS EARLY NEXT WEEK (MON AND TUES) CONTINUE TO WARM INTO THE MID 50S INLAND AND LOW-UPPER 40S COASTAL AREAS THANKS TO COLD WATER. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... AS OF 12Z...IFR/LIFR CONDS ARE FOUND THROUGHOUT THE AREA WITH A WARM FRNT IN THE VICINITY AND VERY MOIST LO LEVELS. THE CHANCE OF -RA HAS DIMINISHED THIS MORNG BUT THERE IS STILL SOME AREAS OF -DZ. SW WINDS GUSTING UP TO 20-25 KT WILL CONTINUE TDA AHEAD OF AN APPROACHING COLD FRNT. SOME IMPROVEMENT IN CIGS IS EXPECTED THIS AFTN AT MOST TAF SITES...BUT IFR/MVFR IS STILL PSBL. THE COLD FRNT DROPS INTO THE AREA THIS EVENG INTO TNGT...WITH RAIN AND LIFR/IFR CONDS EXPECTED. DURING THE DAY THU...THE PCPN BECOMES SNOW NRN PORTIONS AND MIXED PCPN SRN PORTIONS. PCPN BECOMES MAINLY SNOW THU EVENING BEFORE ENDING FROM THE NW. ANY SNOW ACCUMULATIONS ARE EXPECTED TO BE AROUND 1-3 IN ON AVG...WITH PSBLY MORE AT KSBY. A GUSTY NORTHERLY WIND WILL DEVELOP ALONG THE COAST THU. HIGH PRESSURE THEN BUILDS IN WITH DRY WEATHER FRIDAY THROUGH SUNDAY. && .MARINE... A COLD FRNT APPROACHES FM THE W TDA WITH S/SW FLOW CONTINUING OUT AHEAD OF THE FRNT. WINDS MAY COME CLOSE TO SCA THRESHOLDS THIS MORNG OVER THE LWR BAY DUE TO A STRONG LLJ...BUT WAA AND COLD WATERS WILL CAUSE A SHARP INVERSION THAT SHOULD KEEP SUSTAINED WINDS UP TO ~15 KT THERE. ISSUED A DENSE FOG ADVSRY FOR CSTL WTRS S OF CAPE CHARLES LIGHT DUE TO EXPECTED VSBYS AOB 1 MI THRU THE MIDDAY HRS IN ASSOCIATION WITH VERY MOIST LO LEVELS. THE FRNT SLOWLY DROPS THRU THE AREA LATE TDA INTO TNGT AS A WAVE OF LO PRES DEVELOPS ALONG THE FRNT. AS THE FRNT FINALLY PUSHES S OF THE AREA TNGT...SCA CONDS WILL COMMENCE OVR THE WTRS. THESE CONDS WILL CONTINUE INTO THU NGT AS WELL SO EXTENDED THE HEADLINES INTO THE 4TH PERIOD. WINDS MAY COME CLOSE TO GALE FORCE OVR SRN CSTL WTRS BUT CONFIDENCE IS NOT HI ENUF TO ISSUE A GALE WATCH/WARNG ATTM. ALSO KEPT ALL RIVER ZONES EXCEPT THE LWR JAMES OUT OF THE ADVSRY FOR NOW BUT WILL CONTINUE TO MONITOR. WAVES OVER THE BAY UP TO 4-5 FT WITH SEAS OVER CSTL WTRS UP TO 7-8 FT. SFC HI PRES THEN BLDS IN FOR FRI INTO THE WEEKEND LEADING TO IMPROVING MARINE CONDS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR ANZ632>634-637-638- 656-658. SMALL CRAFT ADVISORY FROM 4 AM THURSDAY TO 4 AM EST FRIDAY FOR ANZ630>632-634-650-652-654-656-658. SMALL CRAFT ADVISORY FROM 7 AM THURSDAY TO 4 AM EST FRIDAY FOR ANZ633-638. && $$ SYNOPSIS...AJZ/LKB NEAR TERM...AJZ SHORT TERM...AJZ LONG TERM...SAM AVIATION...MAS MARINE...MAS

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