Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 031426 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 1026 AM EDT Mon Aug 3 2020 .SYNOPSIS... High pressure off the coast will remain in control over the local area into this afternoon. Please see the latest advisories from the National Hurricane Center concerning Tropical cyclone Isaias which is forecast to impact the region later tonight into Tuesday afternoon. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 230 AM EDT Monday... A band of showers/tstms is pushing nwd into NE NC late this morning. Warm and humid this morning with temperatures in the upper 70s to mid 80s. Otw...sfc hi pres off the coast continues to nose itself W into the FA...and will do so through this morning. Eventually this afternoon/early this evening...tropical moisture will begin to increase from the S...leading to the development of areas of SHRAs/tstms. Starting out at least partly sunny for all except far N-W then VRB clouds-mostly cloudy this afternoon. Highest PoPs (60-70%) will generally be W of I 95...tapering to 30-40% E. Locally heavy rainfall and brief gusty winds are poss w/ any SHRAs/tstms later today. Highs in the m-u80s (could RIC break the 90F max streak?). && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... As of 245 AM EDT Monday... No big changes wrt forecast and impacts from TC Isaias late tonight/Tue. Forecast guidance continues to an inland track (landfall near the coast at the NC-SC border tonight). The storm will be moving rather briskly NNE thereafter...which brings it into the local area very late tonight into Tue afternoon (although there are still some timing differences amongst numerical guidance). Please refer to the official NHC forecast for exact details with respect to Isaias. Impacts from Isaias are expected to arrive late tonight and continue into Tue afternoon. High potential exists for (widespread) heavy rain and breezy to windy conditions (for about a 6-8hr time frame at any particular location) well as the potential for isolated tornadoes (ern VA/the ern shore and NE NC). Have made only minor adjustments to the axis of heaviest rainfall and forecast QPF as the storm interacts w/ a trough aloft to the WNW and as a strong upper jet (100+kt at 200 mb) develops N of the tropical low. As this occurs the forward speed of the storm will increase. The latest QPF forecast is still for generally 4-6" along and W of the I-95 corridor...3-5" over the interior coastal plain...and tapering to 1-2" toward the coast. A Flash Flood Watch remains in place for late this evening/tonight through Tue afternoon for most of the area...excluding coastal NE NC, SE VA and the Atlantic coast of the Ern Shore. Strong low-level shear and SRH are expected E of the track bringing a tornado potential initially to NE NC/SE VA late tonight...spreading nwd Tue. The tornado potential and the extent will be dependent on how much destabilization is able to occur E of the track along with the location of any surface boundaries. Lows tonight in the u60s-l70s inland to the l-m70s at the coast. Highs Tue in the u70s-l80s inland to the l-m80s at the coast. Conditions settle down Tues night into Wed as Isaias moves to the NE. There is a chc of diurnal showers/tstms Wed afternoon. Seasonal temperatures with lows in the upper 60s/low 70s Tue night...followed by highs in the upper 80s/low 90s Wed. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 530 PM EDT Sunday... As Tropical Storm Isaias pulls away from the area, a broad upper trough will remain in place across the Great Lakes and Ohio River Valley through Saturday. A sfc trough will be located east of the Appalachian Mountains through the early part of the weekend. This will allow for widespread thunderstorms to develop across the area each afternoon and last until shortly after sunset. Temperatures will not be as hot as previous weeks with the increased tstm chances and associated cloud cover. Highs 87-92F and overnight low temperatures in the upper 60s to mid 70s. Even though dew points will be in the low 70s, heat indices are expected to remain below 100 degrees. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... As of 635 AM EDT Monday... SCT-BKN SC (largely MVFR) for a part of the morning then SCT-BKN CU w/ increases CHCs for SHRAs/tstms this afternoon/evening (which would be accompanied by brief flight restrictions in heavy rain/lower CIGs). Kept VCSH for now given uncertain coverage attm. SSW winds 5-15 kt. More widespread (potentially heavy) rain...reduced VSBY/CIGS...along with breezy to windy conditions are likely late tonight into Tue afternoon as lo pres (tropical cyclone Isaias) crosses the area from south to north. Conditions transition back to more diurnal showers/tstms Wednesday through Friday. && .MARINE... As of 600 AM EDT Monday... Early morning surface analysis shows low pressure centered in southern Quebec with a surface trough extending southward into the Mid-Atlantic states. Tropical Storm Isaias is centered roughly 150 miles SE of Jacksonville, FL moving NNW parallel to the FL coast. Locally, winds across the marine area are SW 15-20 knots from Cape Henry northward and 10-15 knots to the south. A few gusts to 25 knots have been noted overnight, especially at elevated sensors on the east and northeastern Ches Bay. Waves in the bay are 1-3 ft with seas averaging 3-4 ft. Winds will decrease to 10-15 knots and become SSE today as the trough lifts away to the NE. Attention then turns to Isaias. 00z/03 guidance has come into better agreement with respect to the track/intensity of Isaias, but there are still some differences with respect to timing. GFS remains the fastest of the bunch, about 6 hours ahead of the GEM/ECMWF. There have only been minor shifts in the forecast track since last night but global models do show a modest increase in strength over the next 12-24 hours vs the previous forecast, resulting in a slightly stronger wind field for our area. The latest NHC track is faster and shows Isaias making landfall just S of the NC/SC border Monday night before moving to just east of Raleigh. Isaias will likely track NNE near/just to the west of the Chesapeake Bay on Tuesday morning before quickly exiting to the N/NE Tue afternoon. Isaias is expected to maintain tropical storm strength as it tracks through the area, so TS Watches have been upgraded to TS Warnings for the ocean, bay, Currituck Sound, and all of the rivers. Looks like the most likely timing for tropical storm conditions will be from around 2 AM through 2 PM Tuesday. The earliest onset of TS conditions will be across srn marine zones, with the latest onset of TS conditions occurring across nrn marine zones. There is the potential for sustained winds of 40-50 kt with gusts up to 60-65 kt during this timeframe. The strongest winds will generally be from the S or SE across the marine area (E of the center of Isaias). Given that Isaias will be gaining forward speed as it tracks through the area, tropical storm conditions will last no more than 6-8 hours or so at any given location. Will continue to advertise increasing winds /waves-seas late Mon night-Tue AM before winds, waves, and seas quickly decrease Tue evening in the wake of Isaias. Sub- SCA conditions return on Wed and are expected to last through Fri. Please see the latest advisories from the National Hurricane Center concerning the track of Hurricane Isaias. && .TIDES/COASTAL FLOODING... As of 530 AM EDT Monday... Tidal flooding is possible across parts of the area on Tuesday-early Wednesday morning as TS Isaias tracks NNE through the area. Strong S to SE winds for a 6-8 hour period will result in rapidly rising water levels across the mid/upper Ches Bay (especially the bayside of the Lower MD Ern Shore) and also in areas on the north side of the Albemarle/Currituck Sounds. In coordination with neighboring offices, Coastal Flood Watches remain in effect for the bayside of the Lower MD Ern Shore, VA Northern Neck, all counties in NE NC north of the Albemarle Sound, and VA Beach (for sound side flooding). There is the potential for water levels to exceed moderate flood thresholds in the watch area on Tuesday. The latest guidance shows lower potential for water to be trapped in the northern Ches Bay, but the forecast will continue to show minor to low-end moderate flooding on the bayside of the Lower Ern Shore early Wed AM. Thus, the Coastal Flood Watch for the Lower Ern shore runs through ~06z Wed. Watches for NE NC/VA Beach run through Tuesday evening. While a watch has been issued for Northumberland/Westmoreland, confidence remains quite low that Lewisetta will reach moderate flood thresholds. && .CLIMATE... As of 230 AM EDT Monday... RIC official had a high temperature of 96F Sun which made it 24 consecutive days of 90+F temperatures (the 2nd longest streak in the period of record). The longest streak on record is 27 days in 1995. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...Flash Flood Watch from 10 PM EDT this evening through Tuesday evening for MDZ021>023. Tropical Storm Warning for MDZ021>025. Coastal Flood Watch from late tonight through late Tuesday night for MDZ021>023. NC...Flash Flood Watch from 10 PM EDT this evening through Tuesday evening for NCZ012>014-030. Tropical Storm Warning for NCZ012>017-030>032-102. Coastal Flood Watch from late tonight through Tuesday evening for NCZ015>017-030>032-102. VA...Flash Flood Watch from 10 PM EDT this evening through Tuesday evening for VAZ048-060>062-064>069-075>090-092-093-096- 509>524. Tropical Storm Warning for VAZ064-075>090-092-093-095>100- 511>525. Coastal Flood Watch from late tonight through late Tuesday night for VAZ099. Coastal Flood Watch from late tonight through Tuesday evening for VAZ098. Coastal Flood Watch from late tonight through Tuesday evening for VAZ075-077. MARINE...Tropical Storm Warning for ANZ630>638-650-652-654-656-658. && $$ SYNOPSIS...AJZ/ALB NEAR TERM...AJZ/ALB SHORT TERM...AJZ/ALB LONG TERM...CP/JDM AVIATION...ALB MARINE...ERI/RHR TIDES/COASTAL FLOODING...AKQ CLIMATE...AKQ is the U.S. government's official web portal to all federal, state and local government web resources and services.