Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 200845 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 345 AM EST SAT DEC 20 2014 .SYNOPSIS...
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WEAK LOW PRESSURE WILL TRACK FROM THE GULF OF MEXICO EASTWARD AND OFF THE SOUTHEAST COAST THROUGH TONIGHT. HIGH PRESSURE WILL BE OVER THE AREA AGAIN DURING SUNDAY. ANOTHER LOW PRESSURE AREA MOVES NORTHEAST OUT OF THE GULF OF MEXICO AND UP ALONG THE CAROLINA COAST LATE SUNDAY NIGHT THROUGH MONDAY NIGHT.
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&& .NEAR TERM /THROUGH TONIGHT/...
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SFC HIGH PRESSURE OVER THE MID-ATLANTIC TODAY KEEPS DEEPER MOISTURE FROM THE GULF SHUNTED TO OUR SOUTH AS MID LEVEL FLOW REMAINS FAIRLY ZONAL. LATEST RADAR MOSAIC NOT SHOWING MUCH IN THE WAY OF PCPN MAKING IT ANY FARTHER NORTH THAN THE NC/SC BORDER EARLY THIS MORNING...AND LATEST SFC OBS CONFIRM THAT. THEREFORE...WILL KEEP FORECAST DRY THROUGH 12Z. 00Z SUITE OF MODELS TRY TO BRING SOME LIGHT PCPN INTO FAR SOUTHERN PORTIONS OF OUR CWA LATER THIS MORNING INTO THE AFTERNOON. HOWEVER...MODELS HAVE CONTINUED TO TREND DRIER SINCE YESTERDAY...AND WILL LIMIT POPS TO NO MORE THAN 30% ACROSS NE NC THIS AFTN. GENERALLY EXPECTING DRY WX NORTH OF HWY 58 IN VIRGINIA. WITH TEMPS AT OR BELOW FREEZING ACROSS THE PIEDMONT THIS MORNING...AN PCPN THAT FALLS NEAR THE NC BORDER PRIOR TO 15Z COULD BE IN THE FORM OF A SNOW SHOWER OR SLEET PELLETS WITH NO ACCUMULATION. CLOUDY TO MOSTLY CLOUDY TODAY WITH HIGHS IN THE UPR 30S NW TO MID 40S SE. SFC HIGH PRESSURE REBOUNDS TONIGHT WITH DECREASING CLOUDS. LOWS IN THE MID 20S NORTH TO THE LOW 30S SOUTH.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY/...
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HIGH PRESSURE REMAINS ENTRENCHED OVER THE MID-ATLANTIC SUNDAY WITH A MIX OF SUN AND CLOUDS. SEASONABLE HIGHS OF 45-50. NEXT SYSTEM...THIS ONE MORE AMPLIFIED WILL AFFECT THE AREA ON MON...WITH LIKELY TO CATEGORICAL POPS ALL ZONES MON AM/MON AFTN. LOOKS LIKE ALL RAIN ASIDE FROM A BRIEF MIX POSSIBLE AT ONSET IN FAR NW COUNTIES. AT THIS POINT...IT DOES NOT APPEAR ENOUGH FROZEN PCPN WOULD OCCUR TO CAUSE ANY CONCERNS. LOWS SUNDAY NIGHT FROM AROUND 30 NW TO AROUND 40 VA BEACH. HIGHS MON ONLY AROUND 40 NW TO THE MID 50S FAR SE IN CAD SETUP.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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LOW PRESSURE LIFTS TO THE NE MONDAY NIGHT WITH POPS SLOWLY DIMINISHING FROM SW-NE OVERNIGHT. MID-LEVEL RIDGING BRIEFLY BUILDS INTO THE REGION TUESDAY. HOWEVER...MOIST SOUTHERLY FLOW ORIGINATING FROM THE GULF STREAM WILL PREVAIL SO LOW CHC (30%) POPS WILL BE MAINTAINED. A VERY DYNAMIC SYSTEM LIFTS NNE WEST OF THE APPALACHIANS TUESDAY NIGHT WITH THE ATTENDANT COLD FRONT CROSSING THE MID-ATLANTIC WEDNESDAY. THE FIRST POTENTIAL OF RAIN ARRIVES TUESDAY NIGHT ASSOCIATED WITH MOIST WAA. THE SECOND POTENTIAL WILL BE WEDNESDAY AHEAD OF THE COLD FRONT. THERE IS A POTENTIAL FOR THUNDER WEDNESDAY AS SURFACE DEWPOINTS POTENTIALLY EXCEED 60F (ESPECIALLY OVER THE COASTAL PLAIN). THE PATTERN DOES SUPPORT THE POSSIBILITY OF A DYNAMICALLY FORCED LINE OF CONVECTION CONTAINING STRONG WIND GUSTS AS CURRENT FORECAST GUIDANCE SUGGESTS A 925-700MB WIND FIELD AVERAGING 40-50KT. THIS WOULD BE A CLIMATOLOGICALLY RARITY THIS TIME OF YEAR...SO CONFIDENCE IS ON THE LOW-SIDE GIVEN THAT THIS IS 5-6 DAYS OUT. TEMPERATURES WILL BE VERY MILD AHEAD OF THE FRONT TUESDAY AND WEDNESDAY...WITH HIGHS AVERAGING FROM THE MID 50S NW...TO MID/UPPER 60S SE. DRY AND BREEZY CONDITIONS WILL LIKELY PREVAIL BY CHRISTMAS DAY...WITH HIGH TEMPERATURES OF 50-55. THE FLOW BECOMES MORE SW BY FRIDAY WITH CURRENT FORECAST HIGHS OF 55-60...BUT 60-65 IS POSSIBLE BASED ON LOW-LEVEL THICKNESS FIELDS.
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&& .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... VFR CONDS IN PLACE ACROSS THE REGION THIS MORNING, WITH PREDOMINATELY VFR CONDS TO PERSIST THROUGH THE TAF PERIOD. HIGH PRESSURE WILL CONTINUE TO RIDGE SOUTH ACROSS THE REGION FROM THE EASTERN GREAT LAKES/NORTHEAST THROUGH THE TAF PERIOD, AS AN UPPER LEVEL DISTURBANCE MOVES ACROSS THE SOUTHEAST TOWARD THE CAROLINAS TODAY, WHILE ASSOCIATED WEAK SFC LOW MOVES ACROSS THE SOUTHEAST TODAY AND TONIGHT. EAST FLOW WILL ALLOW FOR LOWERING CIGS THROUGH THE MORNING, WITH OVC AT 5-8 KFT AGL EXPECTED THROUGH AFTN. FORCING WILL BE ENOUGH FOR SOME SPOTTY LIGHT RAIN SHRAS, MAINLY IN FAR SRN PORTIONS OF THE AREA. PERIODIC MVFR CIGS WILL BE POSSIBLE ACROSS PHF/ORF/ECG AFTER 18Z. HOWEVER, RAIN SHOULD BE LIGHT ENOUGH TO PRECLUDE ANY VSBY RESTRICTIONS. OUTLOOK...ANY PRECIP COMES TO AN END EARLY SATURDAY EVENING AND CONDITIONS WILL GRADUALLY IMPROVE FROM WEST TO EAST THROUGH THE REST OF SAT NIGHT. HIGH PRESSURE BUILDS TO THE NORTH OF THE AREA SUNDAY. A SERIES OF LOW PRESSURE SYSTEMS AND COMPLEX FRONTAL BOUNDARIES WILL BRING CHANCES FOR RAIN AND PERIODS OF LOW CEILINGS AND VISIBILITIES BEGINNING MONDAY. && .MARINE...
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LATEST OBS HIGH PRESSURE SPREADS EAST ACROSS NEW ENGLAND THROUGH TONIGHT, RIDGING SOUTH INTO THE AREA TODAY. MEANWHILE, WEAK SFC LOW PRESSURE WILL PASS SOUTH OF THE REGION LATER TODAY AND TONIGHT. THIS WILL MAINTAIN LIGHT NORTHERLY FLOW ~10 KT OVER THE MARINE AREA TODAY. HIGH PRESSURE MOVES FARTHER E SUNDAY AND SUNDAY NIGHT, AS LOW PRESSURE DEVELOPS OFF THE SOUTHEAST COAST SUNDAY NIGHT BEFORE TRACKING NE OFF THE LOWER MID ATLANTIC COAST LATER MONDAY AND MONDAY NIGHT. THE RESULTANT TIGHTENING SURFACE PRESSURE GRADIENT WILL ALLOW ONSHORE (EAST) FLOW TO GRADUALLY INCREASE MONDAY AFTN, GRADUALLY BUILDING SEAS MONDAY NIGHT AND EARLY TUESDAY. 15-20KT EASTERLY FLOW OVER THE OCEAN AND LOWER BAY COULD PRODUCE A PERIOD OF SCA CONDITIONS ESPECIALLY OVER THE SRN OCEAN ZONES (MAINLY FOR SEAS) AND LOWER BAY/MOUTH OF JAMES. THERE IS NO CAA IN THE WAKE OF THIS LOW...SO SUB-SCA CONDITIONS SHOULD PREVAIL BEHIND THE SYSTEM LATER MONDAY NIGHT INTO TUESDAY. A STRONG LOW PRESSURE SYSTEM LOOKS TO DEVELOP ACROSS THE OHIO VALLEY, TRACKING WEST OF THE MOUNTAINS TUESDAY NIGHT. HOWEVER, THIS SYSTEM WILL PUSH A STRONG COLD FRONT ACROSS THE MID ATLANTIC COAST LATER WEDNESDAY. SCA CONDITIONS ARE LIKELY WEDNESDAY NIGHT INTO CHRISTMAS DAY AS HIGH PRESSURE BUILDS IN FROM THE WNW.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...JDM/LKB LONG TERM...AJZ/MAS AVIATION...MAM MARINE...MAM

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