Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 210251 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 951 PM EST SAT DEC 20 2014 .SYNOPSIS... WEAK LOW PRESSURE WILL PUSH OFF THE SOUTHEAST COAST TONIGHT...AS HIGH PRESSURE REMAINS OVER THE LOCAL AREA THROUGH SUNDAY EVENING. ANOTHER LOW PRESSURE AREA MOVES NORTHEAST OUT OF THE GULF OF MEXICO AND UP ALONG THE CAROLINA COAST LATE MONDAY INTO TUESDAY...AS HIGH PRESSURE DRIFTS OFF THE NEW ENGLAND COAST INTO THE CANADIAN MARITIMES. A COLD FRONT WILL CROSS THE WEDNESDAY NIGHT WITH HIGH PRESSURE RETURNING BY CHRISTMAS DAY. && .NEAR TERM /THROUGH SUNDAY/... WIDESPREAD BKN-OVC CIGS MNLY 6-9KFT CONTG OVR THE FA ATTM...AND W/O ANY DRYING NOTED ON THE SATELLITE...XPCD TO RMN OVR THE FA THROUGH THE NGT. NUDGED TEMPS UP A FEW DEGS F MOST PLACES DUE TO THE CLDNS. COLDEST SPOTS RIGHT NOW ON THE ERN SHORE. MOST LO TEMPS FM THE M/U20S TO L30S. HIGH PRESSURE REMAINS ENTRENCHED OVER THE MID-ATLANTIC SUNDAY WITH A MIX OF SUN AND CLOUDS. LIGHT WINDS OVERALL WITH A LIGHT ONSHORE NE FLOW OVER THE SE COASTAL ZONES...SEASONABLE HIGHS IN THE LOWER- MID 40S NE TO AROUND 50 F IN SOUTH CENTRAL VA. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... MODELS SHOW NEXT SHORTWAVE TROUGH AMPLIFYING ACRS THE NORTHERN PLAINS SUN NIGHT/MON...AS STRONG UPPER LEVEL RIDGING HOLDS STRONG FROM FLORIDA TO THE CARIBBEAN. MID/UPPER LEVEL FLOW PROGGED TO TURN MORE SW AND THIS WILL HELP STEER LOW PRESSURE NE FROM THE GULF COAST STATES INTO THE SE AND MID ATLC COASTAL WATERS MON/MON NIGHT. POSITION OF SFC HIGH TO OUR N...SHIFTING EAST TO THE NEW ENGLAND COAST BY 12Z/MON IS NOT FAVORABLE FOR LOCKING COLD AIR OVER THE AKQ CWA. STILL SHOULD SEE ENOUGH COLD AIR INITIALLY OVER THE REGION SUN NIGHT/MON MORNING DUE TO CLEAR SKIES THROUGH PART OF THE NIGHT. THIS WILL LEAD TO THE CHC OF A FEW HRS WORTH OF OVERRUNNING FROZEN PRECIP OVER CLIMO FAVORED PIEDMONT ZONES NW OF RICHMOND (WITH LITTLE CHC FOR ANYTHING BUT ALL RAIN OVER THE REST OF THE CWA). LOW LEVEL THICKNESSES (1000-850MB) ARE MARGINAL BUT BUFKIT SOUNDINGS SHOW A NARROW LAYER OF BELOW FREEZING TEMPS AT THE SFC FROM ABOUT 09-15Z/MON AT KCHO (AND LIKELY AT KLKU). STILL SOME QUESTION AS TO HOW FAST PRECIP ARRIVES BUT OVERALL LOOKS LIKE CHANCES RAMP UP SIGNIFICANTLY DURING THE 09-12Z TIMEFRAME. WILL GO WITH A CHC FOR SLEET OVER THE PIEDMONT BETWEEN 09-12Z...TRANSITIONING TO SLEET/FREEZING RAIN FROM ABOUT 12-15Z/MON (ALTHOUGH BECOMING CONFINED TO THE FAR NW BY THIS POINT). IN ANY EVENT...THIS LOOKS LIGHT AS BULK OF DEEPER MOISTURE LIKELY ARRIVES AFTER A CHANGEOVER TO ALL RAIN. ALSO...NOT ANTICIPATING TEMPS IN MID 20S...GENLY CLOSER TO 30-32 F...SO IMPACTS ARE EXPECTED TO BE MINIMAL FOR THE MOST PART. HIGHS MON ONLY IN THE UPPER 30S/AROUND 40 NW TO THE MID 50S FAR SE IN CAD SETUP. MAINTAINING LIKELY TO CATEGORICAL POPS THROUGH MON AFTN...ALTHOUGH QPF AMOUNTS ONLY AVG 0.25-0.50". 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. HIGHS IN THE LOW 60S FAR SE TO THE UPPER 40S NW. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A COASTAL LOW JUST OFF THE MID ATLANTIC COAST CONTINUE TO WASH OUT TUE NIGHT AS A WARM FRONT STARTS TO LIFT NORTH THROUGH THE REGION. MEANWHILE...A VERY STRONG AND VIGOROUS SFC LOW DEEPENS OVER THE OH/TN VALLEYS AND PUSHES A STRONG COLD FRONT TWD THE AREA. INITIAL PUSH OF STRATIFORM PRECIPITATION ASSOCIATED WITH THE WARM FRONT TUE NIGHT WILL LIKELY GIVE WAY TO MORE SHOWERY PRECIPITATION AS THE MID ATLANTIC REGION BECOMES WARM-SECTORED AHEAD OF THE APPROACHING COLD FRONT. THE SFC PRESSURE GRADIENT TIGHTENS SIGNIFICANTLY ON WED AS THE PARENT LOW DEEPENS OVER THE GREAT LAKES AND A STRONG JET STREAK (90-150 KT) NOSES INTO THE REGION FROM THE SSW. HIGHS SHOULD RANGE FROM 60-65 NW AND MD/VA LOWER EASTERN SHORE TO 65-69 FROM ROUGHLY RICHMOND TO SE VA/NE NC. IN ADDITION TO DEWPOINTS APPROACHING 60 DEGREES ACROSS THE SERN HALF OF THE CWA...A THETA-E RIDGE IS EXPECTED TO SURGE NWD ALONG THE SE WED MORNING INTO THE SRN MID ATLANTIC COAST BY WED AFTN/EVENING. THE COMBINATION OF THESE FEATURES/CONVECTIVE PARAMETERS MEANS THAT A SLIGHT CHANCE FOR THUNDERSTORMS HAS BEEN ADDED TO THE FORECAST ACROSS SE VA AND NE NC DURING THE AFTN/EARLY EVENING HOURS. THE FRONT EXITS THE REGION LATE WED NIGHT AND PRECIP WILL TAPER OFF FROM WEST TO EAST...COMING TO AN END EARLY THU MORNING. THE UPPER TROUGH ASSOCIATED WITH THE GREAT LAKES SFC LOW SWINGS THROUGH THE REGION LATE WED NIGHT THROUGH THU AFTN. UPPER LEVEL INSTABILITY AND ABUNDANT SFC MOISTURE FROM RECENT PRECIPITATION SHOULD KEEP SCT-BKN CUMULUS OVER THE AREA THROUGH THE DAY ON THU. CAA OCCURRING BEHIND THE COLD FRONT AND A CONTINUED TIGHT SFC PRESSURE GRADIENT WILL RESULT IN GUSTY WSW WINDS OF 20-25MPH WITH GUSTS AROUND 35MPH...AND SHOULD BE FAIRLY UNIFORM ACROSS THE REGION. THE GUSTY WINDS SHOULD DECOUPLE BY THU EVENING. OVERALL CONDITIONS FRI THROUGH THE WEEKEND SHOULD BE DRY. A LEE TROUGH FORMS ACROSS THE AREA ON FRI AND A WEAK CAD WEDGE DEVELOPS. THE PRESSURE GRADIENT RELAXES BRIEFLY FRI/FRI NIGHT AS HIGH PRESSURE BUILDING OVER THE SE STATES EXTENDS UP INTO THE MID ATLANTIC REGION. MEANWHILE...A BROAD UPPER TROUGH PUSHES A DRY COLD FRONT ACROSS THE REGION ON SAT WHICH WILL USHER MUCH COLDER 850MB TEMPS OVER THE AREA (-5 TO -15C). CAA AND A RE-TIGHTENING OF THE SFC PRESSURE GRADIENT WILL BRING A RETURN TO BREEZY SW WINDS ON SAT AND BREEZY NW WINDS ON SUN BEHIND THE NEXT COLD FRONTAL PASSAGE. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... NO PCPN IS EXPECTED DURING THE 00Z TAF PERIOD. BKN CLOUDS WERE OVER MUCH OF THE AREA. MODEL SOUNDINGS INDICATED DRY AIR ABV 10K FT BUT METARS HAVE BASES JUST BELOW THAT LEVEL. A THIN CLOUD DECK OF AROUND 8-10K FT IS EXPECTED TO DIMINISH TOWARD MORNING. SOME CLOUDS AT 5K FT WERE REPORTED AT ECG. A MOSTLY CLEAR SKY IS FORECAST ON SUNDAY. WINDS WILL BE LIGHT THROUGH THE PERIOD. OUTLOOK...A SERIES OF LOW PRESSURE SYSTEMS AND COMPLEX FRONTAL BOUNDARIES WILL BRING CHANCES FOR RAIN AND PERIODS OF LOW CEILINGS AND VISIBILITIES MONDAY THROUGH WEDNESDAY. A COLD FRONT PASSES THROUGH WEDNESDAY NIGHT WITH VFR CONDS AND DRY WEATHER THURSDAY. && .MARINE... QUIET/BENIGN CONDITIONS EXPECTED ACROSS ALL WATERS TONIGHT THROUGH MOST OF SUNDAY NIGHT AS WEAK HIGH PRESSURE RIDGING RESIDES OVER THE MID ATLANTIC REGION. WINDS WILL GENERALLY BE NORTH 5-10KT WITH WAVES/SEAS AVERAGING 1-2FT. MEANWHILE...LOW PRESSURE CURRENTLY STALLED OFF THE SE COAST GETS ABSORBED INTO ANOTHER LOW PRESSURE SYSTEM TRACKING NE OUT OF THE NERN GULF OF MEXICO TO JUST OFF THE SE COAST TONIGHT (RIDING ALONG THE BOUNDARY LEFT BY THE CURRENT SE COAST LOW). THE NEWLY FORMED SE COAST LOW SLOWLY MOVES UP THE CAROLINA COAST ON MON AND THE MID ATLANTIC COAST MON NIGHT...WASHING OUT ON TUE/TUE NIGHT AS A VERY STRONG AND VIGOROUS SFC LOW DEEPENS OVER THE OHIO VALLEY/GREAT LAKES REGIONS AND PUSHES A STRONG COLD FRONT TWD THE AREA. WINDS TURN TO THE NE SUN NIGHT AND GRADUALLY INCREASE TO 15-20KT FROM SOUTH TO NORTH ON MON. LOW-END SCA CONDITIONS ARE ANTICIPATED TO DEVELOP BY MON AFTN AND PERSIST OVER SRN WATERS THROUGH EARLY MON EVENING...AND OVER NRN WATERS THROUGH LATE MON EVENING. A BRIEF REPRIEVE IN SCA CONDITIONS IS EXPECTED TUE/TUE NIGHT AS THE COASTAL LOW GETS WASHED OUT OVER THE MID ATLANTIC REGION. A WARM FRONT LIFTS NORTH ACROSS THE WATERS ON WED AS A VERY STRONG COLD FRONT APPROACHES THE REGION FROM THE WEST. THE SFC PRESSURE GRADIENT TIGHTENS SIGNIFICANTLY ON WED AS A STRONG JET STREAK (90-150KT) ALSO NOSES INTO THE REGION FROM THE SSW. SOUTH WINDS WILL INCREASE TO SPEEDS OF 15-25KT IN THE SRN WATERS DURING THE MORNING AND IN THE NRN WATERS BY THE AFTN WITH SCA CONDITIONS LIKELY DEVELOPING DURING THE AFOREMENTIONED TIMEFRAMES. SEAS SHOULD RESPOND TO THE SLY WINDS PRIOR TO SEEING THE INCREASED WIND SPEEDS WITH SEAS BUILDING FROM 2-4FT TUE NIGHT TO 4-5FT BY WED MORNING. WAVES WILL BUILD TO 3-4FT ON CHES BAY ON WED. THE COLD FRONT IS EXPECTED TO CROSS THE WATERS WED EVENING AND SOLID SCA CONDITIONS WILL LIKELY OCCUR AHEAD OF AND BEHIND ITS PASSAGE. AM NOT ANTICIPATING GALE FORCE GUSTS UNLESS THEY ARE ASSOCIATED WITH CONVECTIVE SHOWERS WED AFTN/EVENING. SEAS CONTINUE TO BUILD TO 5-9FT WED NIGHT THROUGH THU BEFORE STARTING TO SUBSIDE. S-SW WINDS OF 20-30KT WED NIGHT BECOME WLY ON THU...REMAINING STRONG THROUGH THE DAY THU. THE PRESSURE GRADIENT RELAXES BRIEFLY FRI/FRI NIGHT AS HIGH PRESSURE BUILDING OVER THE SE STATES EXTENDS UP INTO THE MID ATLANTIC REGION. MEANWHILE...A BROAD UPPER TROUGH PUSHES A DRY COLD FRONT ACROSS THE REGION ON SAT WHICH WILL BRING A RETURN TO BREEZY NW WINDS ACROSS THE WATERS LATE SAT NIGHT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...ALB/LKB NEAR TERM...ALB/LKB SHORT TERM...JDM/LKB LONG TERM...BMD AVIATION...LSA MARINE...BMD

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