Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 261828 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 228 PM EDT SAT JUL 26 2014 .SYNOPSIS... HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST TODAY AS A WARM FRONT LIFTS NORTH ACROSS THE AREA THIS AFTERNOON THROUGH TONIGHT. A STRONG COLD FRONT APPROACHES THE REGION ON SUNDAY AND CROSSES THE AREA MONDAY INTO MONDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... BASED ON RADAR TRENDS PAST HOUR...BUMPED UP POPS ACROSS NRN NECK & LWR MD ERN SHORE NEXT FEW HRS AS LINE OF CONVECTION MOVES E. PVS DSCN: WEAK MID LEVEL S/W MOVG EAST ACROSS NRN VA IS RESPONSIBLE FOR THE BKN CLOUD DECK ACROSS THE FA THIS MORNING. LATEST RADAR LOOP SHOWING SCT SHOWERS ACROSS NRN VA AND MD WITH EVEN A FEW LTG STRIKES ACROSS NRN DEL. THIS FEATURE WILL CONTINUE TO MOVE EAST THIS AFTRN. LATEST SHORT RANGE MODELS ARE A BIT MORE BULLISH WITH PCPN CHCS THIS AFTRN...BASICALLY OVERCOMING THE CAP THAT WAS PRESENT ON SNDGS PAST FEW DAYS. BEST SPRT FOR ISLTD SHWRS/TSTRMS WILL BE ALONG & NORTH OF A OFP-IXA-WAL LINE. MID LEVEL CAP WILL BE HARDER TO OVERCOME ACROSS SRN HALF OF FA WHERE IT SHOULD REMAIN DRY. DEWPOINTS ALRDY IN THE M-U60S WITH ONLY MINOR SUPPRESSION DURING AFTN MIXING AS WINDS BECOME S-SW AOB 10 MPH. LOOK FOR HIGHS ARND 90 INLAND...M-U80S ALONG THE COAST. PVS DSCN: TONIGHT...THE REGION BECOMES WELL-ROOTED IN THE WARM SECTOR THIS EVENING AND DEWPOINTS AROUND 70 DEGREES WILL BE COMMON AREAWIDE. A THERMAL/LEE SIDE TROUGH DEVELOPS IN THE WAKE OF THE WARM FRONTAL PASSAGE OVERNIGHT...THUS CAUSING THE SFC PRESSURE GRADIENT TO TIGHTEN AHEAD OF AN APPROACHING COLD FRONT FROM THE WEST (S WINDS BTWN 5-10 MPH). A MUGGY NIGHT WILL BE ON TAP WITH TEMPS/DEWPOINTS BOTH IN THE LOWER 70S. DESPITE CONDITIONS BEING NEAR SATURATION...MIXING OVERNIGHT SHOULD PREVENT FOG FROM DEVELOPING. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... THE THERMAL TROUGH STRENGTHENS ON SUNDAY AND THE SFC PRESSURE GRADIENT TIGHTENS UP EVEN MORE AS A STRONG COLD FRONT APPROACHES THE REGION FROM THE WEST. SHORTWAVE ENERGY EJECTS FROM A PARENT LOW/TROUGH SWINGING THROUGH THE WRN GREAT LAKES ON SUNDAY IS PROGGED TO CROSS NRN VA SUN AFTN/EVENING. CONFIDENCE IS INCREASING REGARDING SEVERE WX POTENTIAL DURING THIS TIMEFRAME. NOT ONLY WILL AMPLE MOISTURE BE PRESENT ACROSS THE REGION (PWATS AROUND 2.00 INCHES AND DEWPOINTS IN THE LOWER 70S) BUT 0-6KM BULK SHEAR INCREASES TO 50-55 KT WITH INCREASING LEVELS OF 850-700MB MUCAPE RANGING FROM 500-2500 J/KG...DEPENDING ON WHICH MODEL SOLUTION IS PREFERRED. SFC LIFTED INDEX VALUES ARE ALSO VERY UNSTABLE (-3 TO -7 DURING THE AFTN/EVENING). MODEL CROSS SECTIONS/TIME HEIGHTS REVEAL PLENTY OF ELEVATED LIFT (INCLUDING THROUGH THE HAIL GROWTH ZONE) AND SOUNDINGS CONFIRM THIS. SOUNDINGS ALSO SHOW INCREASING WINDS WITH HEIGHT WITH DRY AIR ENTRAINMENT IN THE MID LEVELS (SW SFC GUSTS TO AROUND 20 MPH IN THE AFTN). NAM SOUNDINGS SHOW THE WIND PROFILE VEERING WITH HEIGHT WHILE THE GFS IS MORE UNIDIRECTIONAL. ALL OF THE ABOVE CONVECTIVE PARAMETERS SUGGEST THAT ORGANIZED (AND POSSIBLY LINEAR) CONVECTION WILL BE POSSIBLE ON SUNDAY. SOME STORMS MAY BECOME SEVERE WITH DAMAGING WINDS...LARGE HAIL...AND VERY HEAVY RAINFALL. SPC CONFIRMS THIS IN THEIR DAY 2 OUTLOOK WHICH HAS THE ENTIRE WAKEFIELD CWA IN A SLIGHT RISK AREA FOR DAMAGING WINDS AND LARGE HAIL. SUPERCELLS MAY ALSO BE POSSIBLE DUE TO FAVORABLE SHEAR PROFILES...WHICH MEANS ISOLATED TORNADOES CANNOT BE RULED OUT. WILL HIGHLIGHT SEVERE POTENTIAL IN THE HWO. HIGH TEMPS OF 90-95 DEGREES ARE EXPECTED ON SUNDAY. THE COMBINATION OF HEAT AND DEWPOINTS IN THE LOWER 70S WILL BUMP HEAT INDEX VALUES TO 100-104 DEGREES (SUB-ADVISORY). IF THE AREA EXPERIENCES MORE SUNSHINE EARLY IN THE DAY...ESPECIALLY SE VA/NE NC...THEN HEAT INDICES COULD PUSH INTO ADVISORY LEVELS (105-109 DEGREES). WILL NEED TO MONITOR CLOSELY. A BRIEF REPRIEVE FROM ADVERSE WX MAY BE POSSIBLE LATE SUNDAY NIGHT INTO MONDAY MORNING PRE-FROPA. THE COLD FRONT IS EXPECTED TO GAIN MOMENTUM FROM A STRONG SHORTWAVE SWINGING ACROSS THE OHIO VALLEY INTO NEW ENGLAND DURING THE DAY. THIS SHOULD PUSH THE FRONT QUICKLY THROUGH THE AREA MON AFTN/EVENING. THUNDERSTORMS ARE EXPECTED TO BECOME FOCUSED ACROSS SE VA/NE NC DURING THE FRONTAL PASSAGE. THE AFOREMENTIONED CONVECTIVE PARAMETERS FROM SUNDAY WILL ALSO BE IN PLAY ON MONDAY. ALTHOUGH OVERALL VALUES ARE SLIGHTLY WEAKER...THERE IS A CONTINUED THREAT FOR DAMAGING WINDS...LARGE HAIL...AND VERY HEAVY RAINFALL. HIGH TEMPS WILL BE TRICKY DUE TO EXACT PLACEMENT OF THUNDERSTORMS...HOW MUCH DRYING CAN OCCUR POST- FRONTAL...AND HOW AFTN MIXING KEEPS TEMPS ELEVATED DUE TO BREEZY SW-W WINDS WITH GUSTS TO AROUND 25 MPH. CURRENT FORECAST IS FOR HIGHS IN THE LOWER 90S REGIONWIDE. A COOLER AND DRIER AIRMASS FILTERS IN FROM THE NORTH MON NIGHT AS PRECIP COMES TO AN END ACROSS THE SE. LOWS SHOULD RANGE FROM THE LOWER 60S NW TO LOWER 70S SE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF FOR THE EXTENDED PERIOD. LONGWAVE TROF DIGS INTO AND OVR THE MID ATLC REGION MON NGT INTO EARLY THU...BEFORE RETROGRADING BACK INTO THE OH AND MS VALLEYS THU AFTN THRU FRI. COLD FRONT WILL PUSH OFF THE CST MON NGT AND TUE...LINGERS FARTHER OFF THE CST TUE NGT THRU THU...THEN POSSIBLY DRIFTS BACK TWD THE CST LATE FRI. OTHER THAN A SLGT OR SML CHC FOR SHOWERS OVR EXTRM SE VA AND NE NC MON NGT INTO TUE MORNG...WILL HAVE A DRY FCST FOR THE REMAINDER OF THE EXTENDED PERIOD. A MORE COMFORTABLE AIRMASS WILL DOMINATE THE AREA TUE INTO THU...BEFORE A LITTLE MORE HUMIDITY RETURNS ON FRI. MAX TEMPS WILL GENERALLY BE IN THE LWR TO MID 80S THRU THE PERIOD. MIN TEMPS WILL RANGE FM THE LWR 60S TO LWR 70S TUE MORNG...RANGE FM THE UPR 50S TO MID 60S WED AND THU MORNGS...AND RANGE THRU THE 60S FRI MORNG. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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WEAK SFC HI PRES OFF THE CST...WITH A WEAK SURFACE TROUGH EXTENDING FROM THE MID-ATLANTIC THROUGH THE NORTHEAST. SCATTERED SHOWERS AND THUNDERSTORMS ARE FORMING ALONG THIS TROUGH...AIDED BY PASSING MID-LEVEL ENERGY. EXPECTING MAINLY VFR CONDITIONS THROUGH THE 18Z TAF PERIOD...ASIDE FROM A PASSING SHOWER LIMITING VISIBILITIES AT KSBY THROUGH 20Z. S-SW WINDS GUSTING TO 15 KT AND SCT-BKN CLOUDS EXPECTED SUN AS A COLD FRONT APPROACHES THE REGION FROM THE W. POTENTIAL FOR MVFR/IFR CONDITIONS IN ANY CONVECTION DURING THE AFTN THROUGH THE EVENING. THE FRONT IS EXPECTED TO CROSS THE REGION ON MONDAY. NOTE: OBSERVATIONS FROM KSBY ARE NOT READILY AVAILABLE DUE TO A COMMUNICATIONS PROBLEM. RETURN TO SERVICE IS UNKNOWN AT THIS TIME. HOWEVER...CURRENT INFORMATION MAY BE OBTAINED BY CALLING INTO THE ASOS SITE DIRECTLY. AMD NOT SKED WILL BE APPENDED TO THE KSBY TAF UNTIL FURTHER NOTICE.
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&& .MARINE... NO HEADLINES XPCD THROUGH MON. HI PRES SLIDES E OF THE WTRS THROUGH TNGT. S TO SW WINDS WILL AOB 15 KT TDA...INCRS A BIT TNGT...ESP ON THE OCN (TO ABT 20 KT). IN ADVANCE OF APPROACHING CDFNT...SIMILAR CONDS (SSW WNDS AVGG SPEEDS AOB 15 KT) SUN THROUGH MON. THAT CDFNT TO CROSS THE WTRS MON...THEN OFF THE CST MON NGT. WNDS WILL TURN TO THE NW BEHIND THE FNT INTO TUE (W/ A PSBL SURGE IN SPEEDS). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...BMD NEAR TERM...BMD/MPR SHORT TERM...BMD LONG TERM...TMG AVIATION...ALB/DAP MARINE...ALB

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