Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 260841 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 441 AM 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. STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE SUNDAY AND MONDAY. && .NEAR TERM /THROUGH TONIGHT/... THE SFC COLD FRONT THAT BROUGHT SEVERE WX TO THE AREA ON THURSDAY HAS WASHED OUT INTO A WARM FRONT AND IS EXPECTED TO SLOWLY LIFT NWD ACROSS THE REGION THROUGH TODAY...FINALLY EXITING THE AREA BY EARLY SUNDAY MORNING. MEANWHILE AS HIGH PRESSURE SLIDES OFF THE COAST TODAY...DEWPOINTS WILL GRADUALLY RISE THROUGH THE DAY WITH ONLY MINOR SUPPRESSION DURING AFTN MIXING AS WINDS BECOME S-SW AT OR BELOW 10 MPH. TEMPERATURES WILL ALSO BE ON THE RISE WITH HIGHS AROUND 90 INLAND AND IN THE MID-UPPER 80S ALONG THE COAST. A SHORTWAVE PASSES JUST NORTH OF THE AREA LATE THIS MORNING THROUGH THIS AFTN AND MAY KICK OFF A STRAY SHOWER/STORM OR TWO ACROSS FAR NRN COUNTIES. FOR 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 /08Z SATURDAY THROUGH WEDNESDAY/... SFC HI PRES OFF THE CST...W/ LGT SSE WNDS ATTM. WNDS LIGHT ENOUGH...AND RECENT RAINFALL PTNTLLY LEADING TO PTCHY FG (AND MVFR CONDS) NEXT FEW HRS (THROUGH AT SUNRISE). XPCG SCT-BKN CLDNS TDA...W/ LO PROB FOR ANY CONVECTION. S-SW WINDS GUSTING TO 15 KT AND SCT-BKN CLDNS XPCD SUN AS A CDFNT APPROACHES THE REGION FROM THE W. PTNTL FOR MVFR CONDS IN ANY SCT CONVECTION LT MRNG THROUGH AFTN. 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. && .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 SHORT TERM...BMD LONG TERM...TMG AVIATION...ALB MARINE...ALB

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