Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 271929 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 229 PM EST SAT DEC 27 2014 .SYNOPSIS... HIGH PRESSURE WILL SLOWLY DRIFT OFFSHORE TODAY. LOW PRESSURE TRACKS NORTHEAST THROUGH THE TENNESSEE VALLEY SATURDAY NIGHT AND ACROSS THE MID ATLANTIC SUNDAY AS A COLD FRONT APPROACHES FROM THE NORTHWEST. THIS COLD FRONT DROPS THROUGH THE REGION SUNDAY NIGHT. ANOTHER AREA OF LOW PRESSURE TRACKS ALONG THE FRONT AND CROSSES THE REGION SUNDAY NIGHT...BEFORE MOVING OFF THE COAST MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPPER/SFC HIGH PRESSURE OVER THE REGION THIS MORNING HAS PRODUCED DRY CONDITIONS AND CALM-LIGHT SLY WINDS. A WEAK PERTURBATION IN THE SWLY FLOW ALOFT HAS SPREAD SOME HIGH CLOUDS INTO THE REGION...BUT HAVING LITTLE IMPACT ON TEMPS. DEWPOINTS IN THE LOW 30S HAVE KEPT TEMPS STEADY EARLY THIS MORNING...IN THE LOW-MID 30S. UPPER RIDGE AXIS AND SFC HIGH DRIFT OFFSHORE THIS AFTERNOON. LIMITED MIXING DUE TO SUBSIDENCE ALOFT WILL RESULT IN LIGHT RETURN FLOW AND LITTLE RECOVER IN LOW-LEVEL THICKNESS. HOWEVER...TEMPS WILL WARM A FEW DEGS TODAY COMPARED TO 24 HOURS AGO...IN THE UPPER 50S TO LOW 60S INLAND AND MID TO UPPER 50S COASTAL ZONES. INCREASING SWLY FLOW AND AN APPROACHING SHORTWAVE WILL INCREASE MID LEVEL CLOUDS THIS AFTERNOON...WITH SKIES AVG PARTLY CLOUDY. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... STRONG SPEED MAX ROUNDS THE UPPER TROUGH SAT NIGHT AS THE RIDGE AXIS REMAINS OFF THE SE COAST. THIS WILL DEAMPLIFY THE LEADING SHORTWAVE ENERGY AS IT LIFTS INTO THE NE. ATTENDANT SFC LOW DEEPENS AS IT LIFTS INTO SE CANADA. TRAILING COLD FRONT WILL REACH THE OH VALLEY LATE SAT NIGHT AS WAVES OF LOW PRESSURE DEVELOP ALONG THE FRONT. EXPECT SAT NIGHT TO REMAIN DRY OVER THE LOCAL AREA AS RETURN MOISTURE WILL BE SLOW TO ADVECT INTO THE REGION. HOWEVER...WILL MAINTAIN SLIGHT CHANCE-LOW END CHANCE POPS IN THE FAR SW AS OVERRUNNING MAY COME IN QUICKER THAN ANTICIPATED. MILD OVERNIGHT TEMPS IN THE LOW-MID 40S. FRONT DROPS INTO THE LOCAL AREA SUN AS A WAVE OF LOW PRESSURE DEVELOPS OVER THE REGION. UPSTREAM SHORTWAVE ENERGY AND INCREASING WINDS ALOFT WILL PROVIDE UVM AS THE FRONT CROSSES THE REGION. MOISTURE ALSO RAMPS UP THANKS TO INCREASING WINDS ALOFT (30-40 KT H85 WINDS). PRECIP WATERS WILL CLIMB TO AROUND 1.2-1.3 INCHES (+2 STD DEV). THE RESULT WILL BE PRECIP SPREADING SW TO NE ACROSS THE REGION THRU THE DAY. BEST CHANCES WILL BE ACROSS THE NRN LOCAL AREA CLOSEST TO BEST UVM. HIGHS SUN IN THE MID-UPPER 50S INLAND TO LOW 60S SE. INITIAL WAVE OF PRECIP LIFTS THRU THE AREA SUN AFTERNOON. THE FRONT STALLS JUST OFF THE MID-ATLANTIC COAST...EXTENDING SWWD INTO THE SE COASTAL PLAINS AS SWLY FLOW ALOFT CONTINUES. A LULL IS EXPECTED SUN EVENING AS THE LEAD WAVE PUSHES OFFSHORE. THE NEXT SHORTWAVE DEAMPLIFIES AND LIFTS INTO THE REGION LATE SUN NIGHT INTO MONDAY MORNING. SFC LOW DEVELOPS ALONG THE FRONT...LIFTING INTO NC EARLY MON MORNING. ANOTHER ROUND OF WIDESPREAD PRECIP IS EXPECTED SUN NIGHT THROUGH MON. MODEL GUIDANCE BEGINS TO DIVERGE LATE MON INTO MON NIGHT WITH HANDLING THE SFC LOW AS IT EXITS THE COAST. NAM QUICKER TO PUSH THE SFC LOW AND ASSOCIATED MOISTURE OFFSHORE MON AFTERNOON AS THE GFS LINGERS THRU MON EVENING. ECMWF IS SOMEWHERE IN THE MIDDLE. MAINTAINED CHANCE POPS THRU MON AFTERNOON. HIGHS MON RANGE FROM THE MID 40S IN THE N TO MID 50S IN THE SOUTH. UPPER JET AND ADDITIONAL SHORTWAVE ENERGY LIFTS INTO THE REGION MON NIGHT INTO TUES...PROVIDING ADDITIONAL UVM. REMNANT LOW LEVEL MOISTURE WILL RESULT IN ADDITIONAL LIGHT PRECIP MON NIGHT INTO TUES MORNING. TEMP PROFILES EXPECTED TO REMAIN ABOVE FREEZING THRU TUES MORNING...AS THE BEST CAA ARRIVES AS PRECIP PUSHES OFFSHORE LATE MON NIGHT. HAVE MAINTAINED SLIGHT CHANCE POPS THRU TUES MORNING TO ACCOUNT FOR POTENTIAL WRAP AROUND MOISTURE. && .LONG TERM /TUESDAY THROUGH SATURDAY/...
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GFS/ECMWF REMAIN IN GOOD AGREEMENT THROUGH THROUGH THE DAYTIME HOURS ON FRIDAY WITH REGARD TO OVERALL PATTERN. A COLD ZONAL FLOW WILL PREVAIL ALOFT ACROSS THE REGION WEDNESDAY/THURSDAY...WITH HIGH PRESSURE BUILDING INTO AND ACROSS THE AREA. WEATHER IS EXPECTED TO BE DRY WITH TEMPERATURES AT OR A BIT BELOW NORMAL FOR LATE DECEMBER. LOW TEMPS TUESDAY NIGHT AND WEDNESDAY NIGHT IN THE 24 TO 30 DEGREE RANGE /A BIT WARMER NEAR THE COAST/. LOWS THURSDAY NIGHT IN THE UPPER 20S NW TO THE LOWER/MID 30S SE...WITH MIN TEMPS EXPECTED TO OCCUR BEFORE 06Z...AS CLOUDS INCREASE OVERNIGHT. HIGH TEMPS TUESDAY THROUGH THURSDAY IN THE 40S...AND IN THE 40S ALL AREAS FRIDAY... EXCEPT SE VA/NE NC...WHERE 50S LOOK LIKELY. GFS/ECMWF CONTINUE TO DIVERGE FROM NEXT FRIDAY NIGHT THROUGH SATURDAY NIGHT WITH REGARD TO TIMING OF LOW PRESSURE AND ASSOCIATED COMPLEX FRONTAL SYSTEM. GFS REMAINS 12-18 HOURS FASTER THAN ECMWF...WHICH DEVELOPS WAVE ALONG THE FRONT SATURDAY NIGHT...DELAYING FRONTAL PASSAGE UNTIL SUNDAY. REGARDLESS...FRIDAY NIGHT INTO SATURDAY NIGHT NEXT WEEK LOOK TO BE UNSETTLED...WITH CLOUDS AND SHWERS. HOWEVER...TEMPERATURES WILL WARM TO WELL ABOVE NORMAL ON SATURDAY...WITH MANY AREAS IN THE 60S.
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&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/... A LIGHT SOUTHERLY FLOW AND SCT HIGH CLOUDS PREVAILED OVER THE AREA STATES SATURDAY AFTERNOON. MID AND HIGH LEVEL CLOUDS WILL INCREASE TONIGHT AND SUNDAY AS A COLD FRONT APPROACHES FROM THE WEST. PCPN IS EXPECTED TO DEVELOP TO THE WEST AND SPREAD INTO PORTIONS OF THE MID ATLANTIC STATES SUNDAY. THE 12Z NAM HAS TRENDED DRIER THROUGH 18Z AND HELD OFF ON PUTTING PCPN THROUGH THEN. NO FOG ISSUES ARE EXPECTED SUNDAY MORNING WITH TEMPERATURES BEING HELD UP BY CLOUD COVER AND WAA. OUTLOOK...RAIN DEVELOPS FROM THE N/W SUNDAY AFTN AND EVENING WITH PERIODS OF IFR INDICATED SUNDAY NIGHT AND MONDAY MORNING. A TEMPORARY DRYING SHOULD OCCUR LATE MONDAY AND MONDAY EVENING. LOW PRESSURE MOVING ALONG THE FRONT TO OUR SOUTH TO BRING ANOTHER ROUND OF RAIN AND PSBL IFR LATE MONDAY NIGHT INTO TUESDAY. VFR AND DRY WEATHER ARE EXPECTED WEDNESDAY AND THURSDAY. && .MARINE...
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FAIRLY TRANQUIL CONDITIONS EXPECTED ON THE MARINE AREA THROUGH SUNDAY...AS HIGH PRESSURE PREVAILS ALONG/JUST OFF THE VA/NC COAST. SOME INCREASE IN WINDS LIKELY TONIGHT/EARLY SUN...WITH SPEEDS IN THE 10-15 KT RANGE. NEXT FRONTAL SYSTEM APPROACHES THE AREA LATE SUNDAY...AND CROSSES THE AREA SUNDAY NIGHT/MONDAY MORNING. WINDS GRADUALLY DROP OFF AHEAD OF THE FRONT ON SUNDAY...BUT ARE EXPECTED TO INCREASE OUT OF THE N/NE ON MONDAY. MODELS HAVE COME INTO LINE WITH EARLIER FORECAST REASONING...AND ARE NOW INDICATING A STRONGER SURGE...WITH WIND SPEEDS NEAR SCA CRITERIA POSSIBLE MONDAY/MONDAY NIGHT. ALSO EXPECT THAT SEAS WILL EVENTUALLY BUILD TO 5 FT OVER AT LEAST THE SOUTHERN COASTAL WATERS LATE MON-TUE IN N/NE FLOW OF 15-20 KT. MAY NEED SOME SCA HEADLINES DURING THAT TIMEFRAME. SFC HIGH PRESSURE SLOWLY BUILDS INTO THE AREA BY MIDWEEK...WITH WINDS/SEAS DIMINISHING.
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&& .EQUIPMENT... KDOX 88D RADAR IS EXPECTED TO BE OUT OF SERVICE THROUGH AT LEAST WED 12/31. SEE FTMDOX (FREE TEXT MESSAGE) FOR DETAILS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...MAM NEAR TERM...SAM SHORT TERM...SAM LONG TERM...WRS AVIATION...LSA MARINE...LKB/WRS EQUIPMENT...

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