Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 021611 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1211 PM EDT THU OCT 2 2014 .SYNOPSIS... HIGH PRESSURE BUILDS OVER THE MID ATLANTIC REGION THROUGH FRIDAY. A STRONG COLD FRONT CROSSES THE AREA SATURDAY MORNING...USHERING IN MUCH COOLER AND DRIER WEATHER FOR THE END OF THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... FOG HAS BURNED OFF...BUT PLNTY OF SCT-BKN SC ARND THE FA ATTM FOR SKIES TO BE VRBLY CLDY. EXPECT SKIES TO AVG PT SUNNY THRU THE AFTRN HRS. GIVEN THE LL MSTR AND HTNG...CAN`T COMPLETELY RULE OUT AN ISLTD SHWR...BUT CHCS ARE ARND 10% SO KEPT MENTION OF ANY POP OUT OF FCST FOR NOW. ANTHR WRM AND RTHR HUMID DAY WITH HIGHS 75-80. PVS DSCN: HIGH PRESSURE AT THE SFC AND ALOFT WILL PIVOT OFFSHORE TONIGHT AND EARLY FRIDAY, ALLOWING LIGHT LLVL FLOW TO SHIFT AROUND TO THE E-SE. NAM FAMILY MODELS STILL KEYING IN ON SOME ADDITIONAL AREAS OF LIGHT OVERRUNNING IN THE LATE NIGHT HOURS TNGT/ERY FRIDAY. WHILE THIS COULD PORTEND TO ANOTHER ROUND OF ISO SHRAS/SPRINKLES...LIFT IS SHALLOW ENOUGH THAT ACCUMULATING PCPN IS NOT ANTICIPATED. THUS, HV HELD OUT OF FORECAST FOR NOW AND WILL CAP POP AT 14% ACROSS I-95 AND WEST. WENT WITH MILDER ENVELOPE OF MOS GUIDANCE WITH ONSHORE FLOW. LOWS GENERALLY LOW 60S, WITH SOME U50S OVER THE FAR NORTH- NORTHEASTERN ZONES. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... FORECAST MODELS CONTINUE TO SLOW THE APPROACH OF THE MID-UPPER TROUGH DIVING SOUTHEAST ACROSS THE UPPER MIDWEST AND UPPER GREAT LAKES ON FRIDAY, WITH ITS ASSOCIATED STRONG SFC COLD FRONTAL PASSAGE PUSHING ACROSS THE OH/TN VLYS FRIDAY AND FRI NIGHT. EXPECT A RATHER MILD AND PLEASANT DAY AHEAD OF THE FRONT WITH HIGHS IN THE LOW 80S INLAND...MID TO UPPER 70S EASTERN SHORE AND COASTAL ZONES. FRONT WILL SWEEP ACROSS THE AREA FRIDAY NIGHT...REACHING THE COASTAL ZONES BY SUNRISE SAT MORNING. OVERNIGHT LOWS FRIDAY NIGHT IN THE 60S. AS FAR AS TIMING POPS, ARW/NMM SEEM IN GOOD AGREEMENT WITH LATEST 00Z ECMWF IN BRINGING A DECAYING LINE OF SHRAS TOWARDS THE REGION LATE FRIDAY AFTN INTO FRI NIGHT. PW VALUES QUICKLY RAMP UP INTO 1.50-1.75 RANGE, SO HIGH CHC TO LKLY POPS FRIDAY NIGHT LOOK GOOD. HOWEVER, DYNAMICS/INSTABILITY PARAMETERS LOOK ANEMIC DUE TO LATE NIGHT FROPA TIMING AND THE ORIENTATION OF THE TROUGH WELL TO OUR N-NW. THUS, HAVE DECIDED TO HOLD THUNDER WORDING OUT OF THIS PACKAGE. DID ALLOW FOR SOME SCT SHRAS LATE FRIDAY AFTERNOON ACROSS OUR WESTERN TIER OF COUNTIES, WITH POPS RAMPING UP FRIDAY NIGHT OVER THE I-95 CORRIDOR AND OVERNIGHT FRIDAY OVER THE EASTERN SHORE. TOTAL QPF IS GENERALLY AROUND A QUARTER INCH ACROSS THE AREA, SLIGHTLY MORE ACROSS THE NORTH. POPS RAMP DOWN FROM WEST TO EAST QUICKLY SATURDAY MORNING, WITH A CLEARING SKY FROM MID MORNING THROUGH AFTERNOON. USED THICKNESS TOOLS FOR MAX T ON SATURDAY, BUT DO EXPECT WEST (DOWNSLOPING) WINDS ALONG W/PLENTY OF AFTN SUNSHINE TO HELP BOOST TEMPS A DEGREE OR TWO WARMER. HIGHS U60S/AROUND 70 IN THE PIEDMONT TO LOWER 70S ACROSS THE COASTAL PLAIN. COOLEST NIGHT OF THE YOUNG FALL SEASON IS EXPECTED SATURDAY NIGHT. BEST COLD AIR ADVECTION WILL REMAIN NORTH AND WEST OF THE LOCAL AREA, BUT H85 TEMPS DO DROP TO BETWEEN 0-2 DEG C SUNDAY MORNING. EXPECT A PLEASANT, CHILLY NIGHT SAT NIGHT WITH LOWS IN THE LOWER TO MIDDLE 40S...TO NEAR 50 ALONG THE COAST UNDER A MOSTLY CLEAR SKY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... LONG TERM PERIOD WILL FEATURE MAINLY DRY AND SEASONABLE CONDITIONS. MID-LEVEL TROF AXIS AND ASSOCIATED SFC COLD FRONT PUSHES FARTHER OFFSHORE SUN. HI PRES THEN BLDS INTO THE SE U.S. SUN AFTN WITH SW FLOW DEVELOPING ACROSS THE MID ATLANTIC. EXPECT A SUNNY SKY WITH HI TEMPS IN THE MID TO UPR 60S. DRY CONDITIONS CONTINUE INTO MON WITH A BROAD UPR-LEVEL TROF OVR THE E HALF OF THE CONUS AND SFC HI PRES SLIDING OFFSHORE. HI TEMPS NEAR NORMAL...IN THE LO TO MID 70S. FOR TUE/WED...A MID-LEVEL SHORTWAVE TROF AND WEAK SFC FRONTAL BOUNDARY WILL CROSS THE MID ATLANTIC LEADING TO A SLGT CHANCE FOR A SHRA. DIFFICULT TO TIME THIS FAR OUT BUT EITHER WAY NOT EXPECTING A LARGE AMOUNT OF PRECIP WITH THIS SYSTEM. HI TEMPS BOTH DAYS STILL IN THE LO TO MID 70S WITH LOWS RANGING THRU THE 50S. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... AREAS OF MVFR FOG/MIST HAVE DEVELOPED EARLY THIS MORNING WITH VISIBILITIES PRIMARILY RANGING FROM 2-5SM. THERE ARE SOME ISOLATED POCKETS OF IFR FOG/CIGS OBSERVED AT TIMES...THEREFORE OCCASIONALLY RAPID BUT BRIEF REDUCTIONS IN FLIGHT CONDITIONS SHOULD ALSO BE ANTICIPATED. AS WITH THE PAST FEW MORNINGS...FOG SHOULD LIFT/DISSIPATE BTWN 02/1300-1400Z. THE COMBINATION OF LIGHT ONSHORE FLOW AT THE SFC AND LIGHT NW WINDS ALOFT WILL ALLOW A MID LEVEL CLOUD DECK TO PERSIST THROUGH TODAY...GENERALLY 4-9 KFT AGL. FOG POTENTIAL SLOWLY WANES FOR TONIGHT AS UPPER RIDGING MOVES DIRECTLY OVERHEAD. PATCHY FOG MAY DEVELOP ALONG/WEST OF INTERSTATE 95...OTHERWISE THE REST OF THE AREA SHOULD REMAIN FOG-FREE DUE TO WEAK COLD AIR ADVECTION CLOSER TO THE COAST. A STRONG COLD FRONT APPROACHES THE MID ATLANTIC REGION ON FRIDAY AND SE WINDS WILL BECOME BREEZY BY FRIDAY AFTN WITH GUSTS AROUND 15 KT. THE SFC PRESSURE GRADIENT TIGHTENS SIGNIFICANTLY WITH THE FROPA FRI NIGHT INTO SAT. EXPECT S-SW WINDS TO STRENGTHEN AHEAD OF AND ALONG THE FRONT...TURNING TO THE W-NW BEHIND THE FROPA WITH WIND SPEEDS REMAINING ELEVATED THROUGH SATURDAY DUE TO NOTICEABLY COOLER TEMPS AND STRONG COLD AIR ADVECTION. MODERATE TO HEAVY RAINFALL WILL ALSO BE POSSIBLE AT TIMES DURING THE FROPA. HIGH PRESSURE AND DRY CONDITIONS RETURN TO THE REGION LATE SATURDAY AFTN INTO EARLY NEXT WEEK WITH PLEASANT FLYING CONDITIONS ANTICIPATED. && .MARINE... CONTINUED LIGHT N-NE WINDS AOB 10 KT WILL PERSIST ACROSS MOST LOCATIONS THIS MORNING. N-NE WINDS OF 15-20KT WILL OCCUR OFF THE NRN COASTAL WATERS (FROM 10-20NM) DUE TO THE PRESENCE OF A QUASI-STATIONARY LOW PRESSURE SYSTEM THAT IS WELL EAST OF NEW ENGLAND. THIS FEATURE WILL PROVIDE JUST ENOUGH OF A PRESSURE GRADIENT TO KEEP WINDS ELEVATED HERE. OBSERVED SEAS AT BUOY 44009 KEEP FLUCTUATING BTWN 4.3-4.6FT NEAR 20NM AND EXPECT THIS TO CONTINUE THROUGH TODAY...HOWEVER IT IS NOT WIDESPREAD ENOUGH TO WARRANT SCA FLAGS ATTM. OTHERWISE...SEAS WILL AVERAGE 3-4FT ALL WATERS TODAY/WAVES 1-2FT. A STRONG COLD FRONT APPROACHES THE MID ATLANTIC REGION ON FRI AND STARTS TO PUSH THE OFFSHORE NEW ENGLAND LOW EWD. THIS WILL CAUSE THE PRESSURE GRADIENT TO RELAX OVER ALL WATERS ON FRI WITH NE-E WINDS AOB 10KT FOR MOST OF THE DAY. THE COLD FRONT IS EXPECTED TO CROSS THE WATERS LATE FRI NIGHT INTO SAT. WINDS VEER TO THE SE-S ON FRI EVENING INTO EARLY SAT AHEAD OF/ALONG THE FRONT WITH SPEEDS INCREASING TO 15-20KT AND GUSTS AROUND 25 KT. WINDS THEN SWING AROUND TO THE W-NW BEHIND THE FRONT BY EARLY SAT AFTN. A PERIOD OF SCA CONDITIONS MAY BE POSSIBLE LATE FRI THROUGH SAT NIGHT DUE TO WINDS AND SEAS/WAVES. THE TIMING OF THE FRONTAL PASSAGE MAY SLOW DOWN AS THE ASSOCIATED UPPER TROUGH DIGS INTO THE TN VALLEY FRI/FRI NIGHT...THEREFORE HAVE DECIDED TO HOLD OFF ON ISSUING SCA FLAGS ATTM SINCE THE START TIME IS HIGHLY DEPENDENT ON THE INCOMING/INCREASING PRESSURE GRADIENT (I.E. SCA CONDITIONS COULD BEGIN EARLY FRI AFTN OR LATE FRI EVENING). WINDS AND SEAS DIMINISH SUNDAY AS HIGH PRESSURE BUILDS INTO THE AREA AND STRONG CAA SUBSIDES. && .TIDES/COASTAL FLOODING... TIDAL ANOMALIES ARE EXPECTED TO AVERAGE AROUND 1.0 FT ABOVE NORMAL TODAY THROUGH FRIDAY DUE TO PERSISTENT ONSHORE/NE WINDS. THIS HAS THE POTENTIAL TO PUSH PORTIONS OF THE MIDDLE BAY AND TIDAL POTOMAC INTO MINOR FLOODING THRESHOLDS DURING HIGH TIDE THIS EVENING/TONIGHT AT LEWISETTA AND BISHOPS HEAD. CAMBRIDGE SHOULD STAY JUST BELOW MINOR FLOODING THRESHOLDS BUT WILL NEED TO MONITOR TRENDS FOR THIS EVENING ONCE NEW 12Z MODEL RUNS COME IN. WATER LEVELS WILL AGAIN APPROACH MINOR THRESHOLDS AT THE SAME LOCATIONS FRIDAY EVENING/NIGHT AS THE WIND BECOMES SOUTHERLY AHEAD OF A STRONG COLD FRONT. TIDAL ANOMALIES SHOULD BEGIN TO DECLINE SATURDAY AS THE WIND SHIFTS OFFSHORE/NW BEHIND THE COLD FRONT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ650-652. && $$ SYNOPSIS...MAM NEAR TERM...MPR/MAM SHORT TERM...MAM LONG TERM...MAS AVIATION...BMD MARINE...BMD TIDES/COASTAL FLOODING...AKQ

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