Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 242055 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 355 PM EST WED DEC 24 2014 .SYNOPSIS... LOW PRESSURE WILL LIFT WEST OF THE AREA TONIGHT. THE ASSOCIATED COLD FRONT WILL PUSH ACROSS THE AREA LATE TONIGHT. HIGH PRESSURE WILL BUILD INTO THE REGION CHRISTMAS DAY AND FRIDAY...MOVING OFFSHORE FRIDAY NIGHT THROUGH SATURDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... LATEST WX ANALYSIS CONTINUES TO FEATURE A DEEPENING ~992MB SFC LOW OVER THE EASTERN GREAT LAKES. THE ASSOCIATED SFC COLD FRONT EXTENDED SOUTH TO THE EAST CENTRAL GULF COAST. MEANWHILE, SFC WARM/COASTAL FRONT WAS ORIENTED SW TO NE JUST E-NE OF THE I-85/US-1 CORRIDOR. RESIDUAL COOL-WEDGE AIRMASS CONTINUES TO PERSIST ACROSS THE PIEDMONT, KEEPING TEMPS IN THE LOW 50S ALONG AND W OF THE RIC METRO AREA WITH TEMPERATURES NOW WELL INTO THE 60S OVER MUCH OF E & SE VA INTO NE NC. WV SAT IMAGERY SHOWING BROAD SWATH OF WARM CONVEYOR BELT MOISTURE LIFTING NORTH FROM THE SE COAST ACROSS THE EASTERN THIRD OF THE LOCAL AREA. PCPN HAS BECOME A BIT MORE SCT IN NATURE AS THE POSITIVELY TILTED UPPER TROUGH BEGINS TO LIFT NE AND MID-UPPER DRY SLOT PIVOTS FROM THE THE WESTERN CAROLINAS SWINGS ACROSS THE REGION. HOWEVER, PLENTY OF LLVL MOISTURE TO KEEP OVC WORDING THROUGHOUT THE OVERNIGHT. REGARDING CONVECTIVE POTENTIAL, HAVE CONFINED THUNDER WORDING TO THE WARM SECTOR ALONG COASTAL SE VA AND NE NC, WHERE TEMPS ARE AOA 70 AT 20Z. SPC HAS ADDED THE SE IN A SLIGHT SEVERE RISK FOR TONIGHT IN THE PRESENCE OF A WARM AND MOISTURE RICH AIRMASS AND A STRONG 925-700MB WIND FIELD. HOWEVER, DESPITE STRONG MID LVL SHEAR/0-1KM EHI PARAMETERS...EXPECT THUNDER WILL REMAIN CONFINED TO ALONG AND SOUTH OF THE ALBEMARLE. THUS, WL RETAIN SLIGHT CHC T OVER SE VA AND THE SE COASTAL PLAIN, MAINLY FOR THE LATE AFTN AND EVENING HOURS. HRRR AND NAM HAVE PERFORMED WELL THIS AFTN, BOTH IN THEIR DEPICTION OF THE WEDGE HOLDING ON INLAND AND THE PCPN FIELD THIS AFTN. HI RES MODELS CONTINUE TO DEPICT A BRIEF LULL IN PCPN ACROSS THE PIEDMONT IN ASSOCIATION WITH AFOREMENTIONED MID-LEVEL DRIER AIR PUSHING ACROSS AHEAD OF THE COLD FRONTAL PASSAGE. THE COLD FRONT ARRIVES FROM THE W LATE THIS EVENING AND MOVES W-E ACROSS THE AREA BETWEEN 02-06Z TONIGHT. A BRIEF PD OF SCT SHRAS THEN POSSIBLE ALONG AND AHEAD OF THE FRONT. WENT AHEAD AND CHANGED PCPN CHARACTER TO SHOWERS TONIGHT, WITH STEADIER RAIN COMING TO AN END INLAND NOW, AND BY MID TO LATE EVENING ALONG THE COAST. DROPPED POPS OFF DURING AFOREMENTIONED LULL PERIOD EARLY THIS EVENING, WITH MORE SCATTERED RAIN SHRAS TO PERSIST LATER IN THE EVENING AND AFTER MIDNIGHT...RAPIDLY DIMINISHING BEHIND THE FRONT AFTER 06Z TOWARDS DAWN CHRISTMAS MORNING. BY EARLY EVENING, EXPECT TEMPS TO RANGE FROM THE 50-55 WELL INLAND...MID/UPPER 60S FOR CENTRAL PORTIONS TO AROUND 70 SE. THESE HIGHS WILL BE NEAR DAILY RECORDS...SEE THE CLIMATE SECTION BELOW FOR DETAILS. GIVEN ONLY WEAK CAA, EXPECT TEMPS TO BE SLOW TO DROP OFF OVERNIGHT, LIKELY LINGERING IN THE 50S AND 60S FOR MUCH OF THE NIGHT. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... UPPER TROUGH WILL PIVOT ACROSS THE REGION CHRISTMAS DAY. MEANWHILE, SFC HIGH PRESSURE WILL BUILD IN FROM THE W-SW. A SLOWER FRONTAL PASSAGE WILL RESULT IN A MILD START TO CHRISTMAS MORNING, WITH TEMPS IN THE 50S FOR MOST. THE SKY SHOULD GRADUALLY CLEAR OUT, BECOMING MAINLY SUNNY WITH SCT CU BY AFTN ON A BREEZY W FLOW. AGAIN, ONLY WEAK CAA WILL BE OFFSET BY DOWNSLOPE WARMING, WHICH WILL RESULT IN TEMPS SLOWLY RISING INTO THE U50S TO LOW 60S CHRISTMAS DAY. CLEAR/SEASONABLE THURSDAY NIGHT AS SFC HIGH PRESSURE BUILDS OVERHEAD. CLEAR SKY/LGT WINDS WILL BRING SEASONABLY CHILLY LOWS IN THE UPPER 20S TO MID 30S. SURFACE HIGH PRESSURE SETTLES IMMEDIATELY OFF THE COAST LATER FRIDAY THROUGH SATURDAY, RESULTING IN DRY CONDITIONS, LIMITED MIXING/LIGHT WINDS AND SUNNY CONDITIONS. HIGHS SHOULD GENERALLY BE IN THE 50S, WITH EARLY MORNING LOWS IN THE L-M 30S. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... THE MODELS ARE IN GOOD AGREEMENT TO BEGIN THE PERIOD FRIDAY NIGHT WITH THE STRONG RIDGING OVER THE SOUTHEASTERN US AND HIGH PRESSURE OVER THE SOUTHEAST...CENTERED OVER EASTERN VA/NC. BUT THE MODELS STRUGGLE WITH THE BREAKING DOWN OF THE RIDGE WITH THE GFS BREAKING IT DOWN MUCH MORE QUICKLY THAN THE ECMWF. THE GFS ALLOW THE NEXT COLD FRONT TO DROP INTO THE ARE SAT NIGHT AND MOVES IT SOUTH OF THE REGION BY SUNDAY MORNING...SETTING UP AN OVERRUNNING PATTERN SUNDAY AFTERNOON INTO MONDAY MORNING. THE ECMWF...AND THE 12Z IS FURTHER NORTH WITH FEATURES THAN 00Z RUN...KEEPS THE RIDGE MUCH STRONGER OVER THE SE AND DOES NOT ALLOW THE COLD FRONT TO MOVE THROUGH THE AREA SAT NIGHT. IT STALLS THE FRONT OVER THE AREA ON SUNDAY AND AS A WAVE OF LOW PRESSURE FORMS ALONG THE BOUNDARY AND LIFTS NE INTO THE CENTRAL APPALACHIANS...IT PUSHES GULF MOISTURE INTO THE AREA. THE 00Z ECMWF PUSHED THE WAVE OFF THE COAST BY MONDAY...BUT THE 12Z RUN LIFTS THE LOW TO THE NORTH AND DRAGS A COLD FRONT ACROSS THE REGION ON TUESDAY. SO FOR NOW WITH THE GREAT SPREAD IN THE MODELS...HAVE TRENDED TOWARD HPC/WPC GUIDANCE...WHICH IS SIMILAR TO THE 00Z ECMWF AND BROUGHT THE WAVE INTO THE REGION ON SUNDAY AFTERNOON AND EVENING WITH IT EXITING BY MONDAY AFTERNOON. HAVE INCREASED POPS TO 50% FOR THAT PERIOD...KEEPING SATURDAY DRY. HAVE ALSO GONE DRY ON MONDAY NIGHT INTO TUESDAY. THE BIG DIFFERENCE COMES TO TEMPERATURES AS THE GFS WOULD ALLOW MUCH COLD AIR INTO THE REGION BEGINNING ON SUNDAY THROUGH TUESDAY. THIS COULD ALSO POTENTIALLY LEAD TO SOME WINTRY PCPN WITH WAVE ON SUNDAY NIGHT. FOR NOW HAVE KEPT TEMPERATURES ABOVE FREEZING AND ALL RAIN WITH THE COLD AIR BEING KEPT MORE TO THE NORTH. FOR TEMPERATURES HAVE ALLOW FOR A GRADUAL COOL DOWN THROUGH THE PERIOD WITH THE COLDEST AIR ARRIVING ON TUESDAY WITH HIGHS IN THE 40S. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... AS OF 12Z...ANOTHER BAND OF RAIN WAS PROGRESSING INTO THE CWA FROM THE SW. CIGS AND VSBYS WILL CONTINUE TO BE VARIABLE BUT ARE EXPECTED TO BE PREDOMINANTLY IFR OR LOWER THIS MORNING. A BIT OF IMPROVEMENT IS EXPECTED THIS AFTERNOON AS THE AREA BECOMES WARM SECTORED BUT THE TAF SITES SHOULD BE MAINLY IFR IS STILL EXCEPT AT ORF AND ECG. CONFIDENCE IN THE DEGREE OF IMPROVEMENT IS MARGINAL. A COLD FRONT APPROACHES FROM THE WEST TONIGHT WITH SHOWERS AND A SLGT CHC OF THUNDER (THIS PCPN NOT INCLUDED IN THE TAF). CONDITIONS IMPROVE FROM THE WEST IN THE MORNING AS WINDS TURN TO WESTERLY. OUTLOOK...HIGH PRESSURE DOMINATES THURSDAY AFTERNOON THROUGH SATURDAY WITH DRY WEATHER. A CHC FOR RAIN RETURNS SUNDAY AS LOW PRESSURE APPROACHES FROM THE WEST. && .MARINE... DENSE FOG ADVISORY IS IN EFFECT FOR THE MARINE AREA THROUGH LATE THIS AFTERNOON AS WARM MOIST AIR MOVES OVER THE RELATIVELY COOL WATERS. AS OF 11Z...WINDS WERE BEGINNING TO INCREASE FROM THE SE. SCA STARTED AT 15Z FOR THE MOUTH OF THE BAY AS WAVES WILL SOON REACH 4 FT IN THE CHANNEL. PREVIOUS DISCUSSION... AS OF 08Z...WINDS REMAIN LIGHT OVER THE MARINE AREA BUT ARE FORECAST TO INCREASE FROM THE SE AND THEN S THIS MORNING AS A WARM FRONT MOVES N THROUGH THE WATERS AND LOW PRESSURE DEEPENS OVER THE OHIO VALLEY. SCA IS IN EFFECT FOR ALL THE WATERS EXCEPT THE RIVERS SAVE THE LOWER JAMES. SCA CONDITIONS OVER INLAND WATERS MAY BE MINIMAL AT FIRST DUE TO LIMITED MIXING BUT WILL BECOME MORE FAVORABLE THURSDAY MORNING. HAVE ADDED THE LOWER JAMES WITH TIMES STAGGERED SLIGHTLY FROM THE BAY (STARTING AT 21Z TODAY AND ENDING 3 HOURS EARLIER THURSDAY). LATER SHIFTS MAY NEED TO CONSIDER SCA BEHIND THE COLD FRONT FOR OTHER RIVER ZONES ON THURSDAY MORNING. SCA IS ALREADY IN EFFECT N OF PARRAMORE ISLAND. SEAS ARE EXPECTED TO BUILD TO 5 FT OR HIGHER BY 18Z S OF THERE AND DECIDED TO BEGIN SCA S OF PARRAMORE ISLAND AT 15Z TO ALLOW SUFFICIENT CUSHION. HIGH PRESSURE THEN BUILDS INTO THE REGION ON THURSDAY NIGHT AND LINGERS THROUGH SATURDAY AS A STRONG UPPER LEVEL RIDGE BUILDS INTO THE SOUTHEASTERN US AND KEEPS STRONG HIGH PRESSURE AT THE SURFACE OVER THE REGION THROUGH SATURDAY. LOW PRESSURE APPROACHES FROM THE SW SUNDAY AND MOVES ACROSS THE REGION MONDAY. PRELIMINARY INDICATIONS DO NOT INDICATE THAT A SCA WILL BE NEEDED WITH THIS SYSTEM. && .TIDES/COASTAL FLOODING... TIDAL DEPARTURES AVERAGING 1-1.5FT ABOVE NORMAL, AND HV EXCEEDED LOW END MINOR THRESHOLDS IN THE ONGOING AFTN HIGH TIDE CYCLE AT BISHOPS HEAD. A COASTAL FLOOD ADVISORY REMAINS IN EFFECT UNTIL 8PM AS TIDE CYCLE CONTINUES UNTIL 5-7P AROUND CAMBRIDGE, WHERE WATER LEVELS ARE EXPECTED TO TOP OUT AROUND MINOR FLOOD THRESHOLD. WATER LEVELS SHOULD DROP OFF POST FRONTAL FOR AM TIDE CYCLE ON CHRISTMAS DAY, BUT WILL CONTINUE TO MONITOR FOR POSSIBLE EXTENSION/RE-ISSUE OF ADVY. && .CLIMATE... RECORD HIGHS FOR TODAY 12/24: RICHMOND.......71 F (1988) NORFOLK........75 F (1891) SALISBURY......67 F (1990) ELIZ CITY NC...75 F (1990) && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...COASTAL FLOOD ADVISORY UNTIL 8 PM EST THIS EVENING FOR MDZ021>023. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THURSDAY FOR ANZ630>634- 650-652-654-656-658. SMALL CRAFT ADVISORY UNTIL 1 PM EST THURSDAY FOR ANZ638. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...AJZ/MAM LONG TERM...TMG AVIATION...ESS MARINE...TMG TIDES/COASTAL FLOODING... CLIMATE...

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