Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 281058 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 658 AM EDT THU MAY 28 2015 .SYNOPSIS... HIGH PRESSURE REMAINS ANCHORED WELL OFF THE MID ATLANTIC COAST TODAY...WITH A TROUGH OF LOW PRESSURE NEARLY STATIONARY EAST OF THE MOUNTAINS. HIGH PRESSURE WILL BUILD OVER THE NORTHEAST STATES FRIDAY...THEN SLIDE OFF THE COAST SATURDAY. A SLOW MOVING COLD FRONT WILL ENTER THE LOCAL AREA FROM THE NORTHWEST ON SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... CURRENT ANALYSIS INDICATING SFC HIGH PRESSURE WELL OFF THE MID ATLC/NE COAST...RIDGING SW TO OFF THE NC COAST. SFC COLD FRONT IS SITUATED FROM WRN NY STATE SW INTO THE OHIO VALLEY. FLOW ALOFT IS FROM THE WSW. WV SATELLITE SHOWING DECENT SHORTWAVE PUSHING ACRS THE GREAT LAKES...AND THIS IS PROGGED TO SHIFT EAST INTO NY STATE BY THIS AFTN. FLOW ALOFT BECOMES VERY LIGHT ACRS THE MID ATLC REGION THIS AFTN AS THE SFC COLD FRONT DISSIPATES OFF TO OUR NORTH AND WEAK UPPER RIDGING DEVELOPS IN THE WAKE OF THE SHORTWAVE. NUMERICAL GUIDANCE/MAV/MET POPS ARE QUITE LOW TODAY...SUGGESTING LITTLE IF ANY CHC FOR AFTN CONVECTION. WHILE THIS IS PROBABLY UNDERDONE...THERE WILL BE LITTLE TRIGGER FOR WIDESPREAD PRECIP TODAY OTHER THAN DEVELOPING LOCAL BOUNDARIES AND ML CAPES ON THE ORDER OF 1000 TO 2000 J/KG THIS AFTN. SHEAR IS ABOUT AS WEAK AS IT GETS...10-15 KT OR LESS OF 0-6 KM EFFECTIVE SHEAR. WILL MAINTAIN ABOUT A 30% CHC FOR AFTN/EARLY EVENING TSTMS OVER MOST OF THE AREA....A LITTLE HIGHER (TO AROUND 40%) IN THE FAR NW AS DEVELOPMENT IS MORE LIKELY OVER THE MTNS DUE TO SE LOW LEVEL FLOW. ALSO WILL HAVE A ZONE OF POPS TO ~40% FOR INTERIOR SE VA/NE NC DUE TO POTENTIAL FOR SEABREEZE ENHANCEMENT. AT THE IMMEDIATE COAST POPS WILL TEND TO BE A BIT LOWER/GENLY AROUND 20% WHERE FLOW TURNING ONSHORE FROM THE SE THIS AFTN WILL TEND TO STABILIZE CONDITIONS. WEAK SHEAR WILL MAKE ORGANIZED STRONG STORMS UNLIKELY TODAY...MAIN CONCERN WILL BE LOCALLY HEAVY RAIN IN SLOW MOVING STORMS DUE TO WEAK FLOW AND PWATS OVER 1.50". HIGHS TODAY MAINLY FROM 85-90 F...EXCEPT UPPER 70S TO LOWER 80S AT THE COAST. LOW CHC POPS LINGER THIS EVENING...MAINLY WELL INLAND...OTHERWISE PARTLY CLOUDY WITH LOWS MAINLY FROM 65-70 F. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... WK SFC HI PRES SLIDES E ACRS NEW ENG FRI. MDLS SHOW A SLGT DROP IN DEWPTS ACRS FAR NNE COUNTIES FOR THE DAY...WHILE RMNG UP ELSW. HI PRES JUST OFFSHORE BEGINS TO SLGTLY BUILD WWD DURING THE DAY...SO FOCUS OF HIGHER POPS (30-40%) NW 1/2 OF FA WITH ONLY 10-20% POPS ELSW. BY SAT...CDFNT FM THE NW APPROACHES...THOUGH RMNS FAR ENOUGH AWAY FOR SIGNIFICANT IMPACT ON THE WX HERE. WILL KEEP CONDS WARM W/ VRB CLDS/PCLDY AND MAINLY JUST ABOUT A 20% POP INLAND...10% AT THE CST. HI TEMPS FRI A TAD COOLER MAINLY IN THE MID TO UPPER 80S INLAND...70S AT THE CST. LO TEMPS M60S- ARND 70F. SAT A LITTLE WARMER WITH HIGHS UPPER 80S/NEAR 90 F INLAND TO THE 70S TO LWR 80S AT THE COAST. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... THE MEDIUM RANGE PERIOD REMAINS CHARACTERIZED BY MID/UPPER LEVEL RIDGING OVER THE ERN CONUS WITH A TROUGH LINGERING OVER THE INTERMOUTAIN WEST. SURFACE HIGH PRESSURE BUILDS ACROSS ERN CANADA SATURDAY NIGHT AND SUNDAY PUSHING A COLD FRONT INTO THE NRN MID ATLANTIC. 12Z GFS/ECMWF DIVERGE SUNDAY NIGHT/MONDAY WITH THE GFS BRINGING THE SURFACE COLD FRONT THROUGH THE LOCAL AREA SUNDAY NIGHT AND THE ECMWF WAITING UNTIL MONDAY. HIGH PRESSURE SETTLES IN VICINITY OF THE NEW ENGLAND COAST TUESDAY AND WEDNESDAY...AND MOVES OFFSHORE THURSDAY. THE BEST FOCUS FOR CONVECTION APPEARS TO BE SUNDAY AFTERNOON/EVENING AHEAD OF THE COLD FRONT WITH 40-50% POPS FORECAST ACROSS THE NRN HALF OF THE AREA. THE WIND PROFILE WILL REMAIN WEAKLY SHEARED SO ANY THUNDERSTORMS SHOULD BE RATHER UNORGANIZED. POPS MONDAY AFTERNOON AND EVENING ARE FORECAST TO BE 30-40% MONDAY AFTERNOON/EVENING...AND THEN TREND DOWNWARD TO 20-30% BY TUESDAY AND SUB-15% THROUGH MIDWEEK AS SURFACE HIGH PRESSURE PREVAILS. HIGH TEMPERATURES SUNDAY ARE FORECAST TO RANGE FROM THE MID TO UPPER 80S...WITH UPPER 70S TO LOW 80S BEHIND THE FRONT TUESDAY THROUGH THURSDAY. LOWS SHOULD AVERAGE THROUGH THE 60S. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... HIGH PRESSURE REMAINS CENTERED WELL OFFSHORE THIS MORNING WITH A SFC TROUGH JUST EAST OF THE MOUNTAINS. THE RESULT IS S-SW FLOW WITH SPEEDS GENERALLY 5-10 KT. PATCHY FOG/STRATUS OVER AREAS THAT RECEIVED RAINFALL LAST NIGHT...BUT VFR CONDITIONS PREVAIL AT THE TAF SITES. ANY REMAINING FOG/STRATUS QUICKLY BURNS OFF BY 12-13Z. FOR TODAY...SFC WINDS BECOME SELY (AOB 10 KT) THIS AFTERNOON AS HIGH PRESSURE PUSHES FARTHER OFFSHORE AND A COLD FRONT WASHES OUT NW OF THE REGION. SCATTERED AFTERNOON AND EARLY EVENING SHOWERS AND THUNDERSTORMS ARE EXPECTED AGAIN TODAY. BEST COVERAGE EXPECTED TO BE ACROSS THE SE COUNTIES AND W COUNTIES. SCT-BKN CU DEVELOP THIS AFTERNOON WITH DECKS GENERALLY BETWEEN 3-5K FT AGL. GUIDANCE INDICATES MORE FOG/STRATUS OVERNIGHT...BUT WILL BE DEPENDENT ON WHERE PRECIP OCCURS TODAY. UPPER/SFC HIGH PRESSURE REMAINS OVER THE REGION INTO THE WEEKEND. DRY CONDITIONS ARE EXPECTED TO PREVAIL...BUT THERE IS A CHANCE FOR DIURNALLY DRIVEN SHOWERS/THUNDERSTORMS ACROSS THE PIEDMONT FRI- SAT. BETTER CHANCES FOR MEASURABLE PRECIP EXPECTED SUN-MON AS A COLD FRONT REACHES...AND THEN STALLS OVER THE REGION. && .MARINE... HIGH PRESSURE REMAINS CENTERED WELL OFF THE MID-ATLANTIC COAST EARLY THIS MORNING WITH A WEAK SFC TROUGH JUST WEST OF THE WATER. THE RESULT IS A SW WIND OF 10-15 KT. WAVES HAVE SUBSIDED TO GENERALLY 1 TO 2 FT WITH SEAS RUNNING 2 TO 4 FT (HIGHEST IN THE NRN COASTAL WATERS). HIGH PRESSURE PUSHES FARTHER OFFSHORE TODAY AS A WEAK COLD FRONT DROPS INTO THE REGION...WASHING OUT WEST OF THE WATERS THIS AFTERNOON. FLOW BECOMES SELY THIS AFTERNOON...AVERAGING 10-15 KT. SELY FLOW AOB 10 KT PERSISTS FRI. GRADIENT STRENGTHENS FRI NIGHT-SAT AS A COLD FRONT APPROACHES FROM THE WEST. SPEEDS REMAIN SUB-SCA. SEAS BUILD TO 3-4 FT FRI NIGHT-SAT THANKS TO PERSISTENT AND INCREASING SE FLOW. COLD FRONT REACHES...AND THEN STALLS OVER THE REGION SUN INTO EARLY NEXT WEEK. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...ALB/LKB LONG TERM...AJZ AVIATION...SAM MARINE...SAM

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