Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 141455 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1055 AM EDT MON JUL 14 2014 .SYNOPSIS...
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LOW PRESSURE MOVES ACROSS THE GREAT LAKES REGION TODAY WITH A TRAILING COLD FRONT APPROACHING THE LOCAL AREA FROM THE NORTHWEST TONIGHT INTO TUESDAY MORNING. THE FRONT IS EXPECTED TO SLOWLY PUSH THROUGH THE LOCAL AREA TUESDAY AFTERNOON AND NIGHT. THE FRONT PUSHES OFF THE COAST ON WEDNESDAY...AS HIGH PRESSURE BEGINS TO BUILD IN FROM THE NORTHWEST.
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&& .NEAR TERM /THROUGH TONIGHT/...
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ANOMALOUSLY DEEP UPPER LOW OVER SOUTHERN CANADA LOOKS TO PUSH A STRONG SHORTWAVE SE THROUGH THE GREAT LAKES/UPPER MIDWEST TODAY. THIS ALLOWS LOW LEVEL FLOW FROM THE SW TO INCREASE ACROSS THE LOCAL AREA...FOR ANOTHER VERY WARM TO HOT AFTN. HIGHS AGAIN 90-95...EXCEPT COOLER 80S AT THE BEACHES. FORCING FOR ASCENT WILL REMAIN RATHER MINIMAL ACRS THE LOCAL AREA MUCH OF TODAY...BEFORE INCREASING SOMEWHAT BY LATE AFTN/EVENING INTO THE OVERNIGHT HOURS. IN ADDITION...STRONG SW FLO IN THE BOUNDARY LAYER OFTEN DRIES THE AKQ CWA OUT (ESPECIALLY SE VA/NE NC). THEREFORE...WILL MAINTAIN CHC POPS (30-40%) ACROSS FAR N-NW PORTIONS OF THE CWA UNTIL EVENING...TAPERING TO ONLY 15-20% POPS IN SE VA/NE NC. BETTER FORCING DOES ARRIVE TNGT...ESPECIALLY NW-W PARTS OF THE CWA. HOWEVER...THIS WILL LARGELY BE OFFSET BY POOR DIURNAL TIMING. SPC HAS BACKED OFF ON THEIR SLIGHT RISK AREA FOR THE LOCAL AREA TODAY...BASICALLY KEEPING IT ACRS OUR NW/NRN MOST COUNTIES...WHICH IS IN LINE WITH THE AFOREMENTIONED REASONING. SHWR/TSTM COVERAGE SHOULD ACTUALLY INCREASE ACRS THE CWA TNGT GIVEN HEIGHT FALLS AND APPROACH OF A SFC COLD FRONT (POPS 30-50%). WARM TNGT WITH LOWS MAINLY 70-75.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... BY TUE...MODELS IN DECENT AGREEMENT W/ TIMING...THE SFC COLD FRONT MOVES INTO THE REGION AND UPPER LEVEL SUPPORT INCLUDING RRQ FORCING FROM THE UPPER JET ARRIVES LATER IN THE DAY. STILL SOMEWHAT UNCLEAR AS TO PRECIP COVERAGE IN THE MORNING HRS DUE TO VARYING MODEL SOLUTIONS AND PRESENCE OF OLD BOUNDARIES FROM TONIGHT. WILL CARRY HIGH CHC POPS MOST AREAS IN THE AM HRS WITH LIKELY POPS BY AFTN ALL ZONES...SOME SEVERE POTENTIAL EXISTS (MAINLY STRAIGHT LINE WIND THREAT) AS DEEP LAYER SHEAR VALUES INCREASE TO > 30 KT (NOT BAD FOR TIME OF YR). SEVERE THREAT WILL TEND TO TRANSITION TO MAINLY A HEAVY RAIN THREAT BY TUE NIGHT AS THE COLD FRONT SLOWLY MOVES EAST. BEST CHANCE OF SEVERE TSTMS ON TUESDAY (SLIGHT RISK BY SPC) WILL BE ACROSS EASTERN PORTIONS OF THE CWA WHERE THE BEST BUOYANCY/INSTABILITY WILL BE LOCATED ALONG AND AHEAD OF THE COLD FRONT. LOCALIZED FLOODING MAY ALSO BE AN ISSUE...AND MAY PERSIST OVERNIGHT TUE INTO WED AM GIVEN SLOW MOVEMENT OF THE FRONT...STRONG FORCING FOR ASCENT...AND PW`S IN EXCESS OF 2 INCHES. WILL CONTINUE TO HIGHLIGHT THESE THREATS IN THE HWO. IF TEMPERED BY CLOUDS/PCPN HIGHS TUE WOULD GENERALLY REMAIN IN THE MID/UPR 80S...BUT COULD REACH INTO THE LOWER 90S IF SOME SUN DEVELOPS FOR A FEW HRS THROUGH MIDDAY. HAVE BLENDED THESE 2 SCENARIOS FOR FCST HIGHS...GENLY GOING UPPER 80S NW TO AROUND 90 F SE. LOWS TUE NIGHT MID 60S NW TO AROUND 70 F SE. ON WED...MODELS NOW ALSO INTO DECENT CONSENSUS REGARDING THE SFC FRONT POSITION...JUST PUSHING OFF THE SE VA/NE NC COAST AS OF 12Z/WED. LOW LEVEL FLOW SHIFTS TO THE N-NE MOST AREAS BEHIND THE FRONT WITH A COOLER/DRIER AIRMASS EVENTUALLY OVERSPREADING THE REGION FROM THE W/NW. LIKELY POPS WILL STILL PREVAIL THRU THE MORNING ALONG THE COAST (CHC POPS ELSEWHERE)...BUT SKIES SHOULD BECOME PARTLY SUNNY ALONG/WEST OF I-95 IN THE AFTERNOON AS ANY LEFTOVER PCPN IS CONFINED TO THE COAST. COOLER W/ HIGHS IN THE UPPER 70S TO LWR-MID 80S. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... LONG TERM PERIOD WILL FEATURE SLGTLY BLO NORMAL TEMPS AND FREQUENT CHANCES FOR PRECIP. FOR THU...SFC HI PRES WILL BE CENTERED OVR THE OH VALLEY WITH A BROAD AREA OF WEAK LO PRES OVR THE SE STATES...AND MID-LEVEL ENERGY APPROACHING FM THE CNTRL PLAINS/MIDWEST. WITH LO PRES NEAR THE CAROLINAS...COULD SEE SOME SHRAS/TSTMS OVR SE AREAS OF THE FA...BUT NOTHING WIDESPREAD EXPECTED. HI TEMPS AVG IN THE MID 80S. THE AFOREMENTIONED SFC HI MOVES OFF THE NE CST FRI...WITH APPROACHING MID-LEVEL ENERGY LEADING TO A CONTINUED CHANCE FOR SHRAS/TSTMS (30-40% POPS). THE PATTERN CONTINUES INTO SAT AND SUN WITH CHANCE POPS. EXACT TIMING OF THE PRECIP IS DIFFICULT TO PREDICT WITH THIS BEING SEVERAL DAYS OUT. HI TEMPS FRI THRU SUN IN THE MID 80S...WITH LO TEMPS IN THE MID TO UPR 60S. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... SURFACE HIGH PRESSURE HAS SETTLED OFF THE SOUTHEAST COAST...WITH LOW PRESSURE WELL N OF THE REGION AND A FRONTAL BOUNDARY ALIGNED FROM NRN NEW ENGLAND BACK THROUGH THE OHIO VALLEY. A SSW WIND WILL INCREASE TO 10-12KT THIS MORNING...WITH GUSTS UP TO 20KT POSSIBLE THIS AFTERNOON. ISO-SCT AFTERNOON/EVENING SHRA/TSRA ARE EXPECTED AS THE AFOREMENTIONED FRONTAL BOUNDARY NUDGES SOUTHWARD. A STRONGER COLD FRONT ARRIVES FROM THE WEST TUESDAY AND TUESDAY NIGHT AND WILL MAINTAIN THE POTENTIAL FOR SHRA/TSRA. THE FRONT SLOWLY MOVES OFFSHORE WEDNESDAY...WITH DRIER AIR PREVAILING THROUGH FRIDAY AS HIGH PRESSURE BUILDS N OF THE REGION. && .MARINE... A SOUTHERLY WIND WILL CONTINUE TO AVERAGE 10-15KT (15-20KT N OF CAPE CHARLES) TODAY AND TONIGHT AS HIGH PRESSURE REMAINS ANCHORED OFF THE SOUTHEAST COAST...AND SECONDARY LOW PRESSURE DEVELOPS OVER THE GREAT LAKES. THIS AREA OF LOW PRESSURE LIFTS N OF THE GREAT LAKES TUESDAY AND TUESDAY NIGHT...WITH THE TRAILING COLD FRONT APPROACHING FROM THE NW TUESDAY...AND SLOWLY CROSSING THE AREA TUESDAY NIGHT. 14/00Z WAVEWATCH BUILDS SEAS TO 5FT OUT NEAR 20NM TONIGHT N OF PARRAMORE ISLAND. HOWEVER...THE NWPS WAVE MODEL BASED ON FORECAST WIND GRIDS KEEPS SEAS AT 4FT...WHICH IS FURTHER SUPPORTED BY OUR LOCAL WAVE ALGORITHM. GIVEN THIS...NO SCA WILL BE ISSUED AT THIS TIME. SHOWERS/TSTMS ARE LIKELY TUESDAY AFTERNOON AND EVENING AS THE FRONT CROSSES THE AREA. A WIND SHIFT TO N IS EXPECTED BEHIND THE FRONT. A MODEST SUB-SCA 10-15KT NORTHERLY SURGE IS POSSIBLE OVER THE BAY EARLY WEDNESDAY AS COOLER AIR FILTERS IN FROM THE NW. HIGH PRESSURE THEN BUILDS N OF THE REGION THROUGH THE END OF THE WEEK AS WEAK LOW PRESSURE LINGERS OVER THE SOUTHEAST. THIS WILL MAINTAIN LIGHT ONSHORE FLOW AOB 10KT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...JDM NEAR TERM...JDM/TMG SHORT TERM...JDM/LKB LONG TERM...MAS AVIATION...AJZ MARINE...AJZ

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