Area Forecast Discussion
Issued by NWS Wakefield, VA

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968 FXUS61 KAKQ 271804 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 204 PM EDT MON JUN 27 2016 .SYNOPSIS... High pressure shifts off the Mid Atlantic coast today, as a cold front slowly approaches from the west. The front will move across the region Tuesday and Tuesday night. Weak high pressure builds in from the north Wednesday and Thursday as the front stalls across the Carolinas. && .NEAR TERM /THROUGH TONIGHT/... Latest GOES water vapor imagery depicts anticyclonic flow over the Southeast states late this morning. The result is a mostly sunny to sunny sky and dry conditions after some early morning patchy fog. Temps have warmed into the mid to upper 70`s late morning. Ongoing forecast is on track, so no changes made. Hi- res guidance still indicating a weakening line of showers ahead of the front tonight, while course resolution models keep the showers together moving into the region. With the lack of upper level support and warm temperatures aloft, the hi-res guidance may be onto something. Have kept POPs unchanged and will await new guidance before making adjustments. Previous Discussion... Today will be a transition from the dry/pleasant weather yesterday when dew pts were primarily in the 50s to one with increasing moisture and humidity as the low level flow veers around to the south. However, still should have a dry day for most areas as showers and tstms develop along the Mtns this aftn and will be slow to push east into the CWA. Model consensus continues to support a broken line of showers and tstms beginning to affect the NW zones sometime late in the aftn, primarily after 20-21Z, with the better chance for storms not making it to areas e and SE of metro Richmond until after 00Z. Have made some minor adjustments to the forecast to best reflect these trends. Highs today will avg in the upper 80s well inland to the upper 70s to lower 80s along the immediate coast (gradient not strong enough to completely keep the typical backing of the wind direction to the SE closer to the coast). Skies will start off mostly cloudy along the coast and become mostly sunny later this morning. Farther inland expect partly to mostly sunny skies for most of the day with increasing clouds late over the NW. Precipitable Water values surge rapidly to around 2.00" this evening/overnight ahead of the approaching cold front. POPS ramp up to likely most areas during the 00-06Z/tue timeframe, though far SE VA and ne NC look to stay mainly dry through that time as shortwave energy rides ENE along or slightly ahead of the cold front. Severe threat for strong wind gusts appears to remain just NW of the area closer to the main jet axis and where storm coverage will be greater prior to sunset and coincident w/ optimal instability. However, The high PW airmass will support this potentially being a moderate to locally heavy rainfall event. Furthermore, the flow aloft will not be that strong from the NW and shifting to the W with low level flow from the SW, creating a fairly slow storm motion and perhaps some training cells. Still not enough confidence to issue a Flash Flood watch, as some of the models depict storms diminishing after sunset w/ loss of daytime heating while others shows coverage of storms maintaining through the night. Will mention potential for heavy rain/flooding in the HWO (mainly NW). Thunder chc greatest through 06z. Lows in the upr 60s to lwr 70s. QPF through 12Z Tue to avg 1.00-1.50" far NW and 0.50 to 1.00" or less elsewhere (but with locally higher amounts possible). && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... The boundary will be slow to push across the region Tuesday as the upper trough and associated cold front slowly moves east. Additional shortwave energy will maintain decent amount of lift across the SE half of the region and have bumped even the morning POPS to likely across this region (30-40% elsewhere). The greatest threat for heavy rain will be across the SE. By aftn, potential for some clearing which could lead to additional storm development. Highs in the low to mid 80s except upper 70s to lower 80s SE sections with more widespread low clouds all day. Convection slowly wanes Tuesday night as drier air arrives in the wake of the front, but upper level shortwave passing across the north may be enough to set off a secondary line of showers/tstms Tue evening, especially across the north. Lows 65-70 F. Broad, upper level trough pushes across the region Wed. This will likely be enough of a trigger for sct convection to develop once again mainly during the afternoon / evening hours, over the south (probably becomes too dry over the north by aftn). Highs in the mid 80s except upr 70s to lower 80s at the beaches. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... The cold front will have pushed well offshore by Wednesday morning with high pressure building in and dominating the weather Wednesday into Thursday. model hint at a few possible showers along the Sound Wednesday night into early Thursday...otherwise dry through mid week with high in the low to mid 80s. The weather pattern becomes more unsettled Friday as a broad upper level trough dominates Thursday night into the holiday weekend. Have increased POPS to high chance over much of the area with the exception of the Eastern Shore Friday afternoon. Showers and storms look to develop late after strong heating with highs Friday in the mid to upper 80s. The pattern changes very little into the holiday weekend with another front pushing though Saturday night into Sunday. This will keep a good chance for showers and storms in the forecast through the weekend. At some point POPS will likely have to be increased for the timing of the front. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... VFR conditions are expected through this evening at all sites. Showers and thunderstorms over the mountains will attempt to move into the region tonight, however it is unclear how widespread they will become. If nothing else, ceilings will lower overnight at all sites and may become MVFR late tonight into Tuesday. There are chances for thunderstorms late tonight, but confidence is not high enough to include in any terminal at this time. Best chance for thunder would be at RIC. Continued MVFR or lower end VFR on Tuesday. OUTLOOK...Chances for thunderstorms will continue Tuesday afternoon into Wednesday as the front moves slowly through the area. This front remains just south of the area through Friday, and with that a chance for showers and storms, especially at ORF and ECG. && .MARINE... High pres was cntrd just off the New England and nrn Mid Atlc cst early this morning, while a cold front was pushing thru cntrl OH and wrn KY. No headlines in the short term today thru Tue ngt. The high will slide farther e into the Atlc during today, as a pre- frntl trough approaches fm the wnw. Winds will become SE or S and increase to 10 to 15 kt for this aftn into tngt. A band of showers and some thunderstorms will approach the Ches Bay and coast later tngt into Tue morning, as the pre-frntl trough slides into and acrs the region. Winds will lessen a bit and become SSW as the trough moves in. SSW flow 5 to 15 kt continues Tue into Tue ngt, as the actual cold front approaches fm the wnw. The cold front and wind shift to a N and NE wind drops through the waters Wed morning into Wed aftn with high pressure pushing into the Grt Lks and OH valley. This will maintain a NE to E flow Wed and Thu. && .CLIMATE... Chances to add to an already wet month mainly tonight and Tue. June has been another wet month at Richmond, the monthly total rainfall through the 24th stands at 6.92" and already makes this the 9th wettest June on record (2004 is wettest June with 9.93"). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...LKB NEAR TERM...LKB/SAM SHORT TERM...LKB LONG TERM...JAO AVIATION...MRD MARINE...TMG CLIMATE...

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