Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 260812 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 412 AM EDT Wed Apr 26 2017 .SYNOPSIS...
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Low pressure lifts along the Northeast coast today, resulting in a warming trend through the remaining work week. A cold front weakens west of the region Thursday night. High pressure prevails through the weekend. The next cold front pushes across the region early next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Latest water vapor and surface analysis depicts vertically stacked low pressure just offshore the Delmarva. Moisture and energy wrapping around the backside of the system is producing an area of light rain/drizzle from the Northern Neck to southeast Virginia. Latest radar trends depict a decrease in coverage, with latest RAP/HRRR guidance pushing the upper level energy offshore shortly after daybreak. As the energy slides offshore, expect light rain to dissipate/slide offshore. Stratus and mixing has limited fog development this morning. Given the upper level cyclonic flow and low cloud bases, patchy/areas of drizzle expected to linger thru mid morning. The surface low weakens and slowly drifts northeast today as an upper level ridge builds in from the west. Cloud deck will be slow to erode/lift thru mid morning, with the late April sun expected to erode the deck inland mid to late morning. However, warming temperatures aloft ahead of the building ridge and wrap around moisture from the departing upper low will keep a partly cloudy to mostly cloudy sky across the area. Cloudy across the far northeast, nearest the upper low and associated energy. While soundings indicate drying aloft for the Maryland Eastern Shore, abundant low level moisture and some modest isentropic lift will keep a chance of rain thru early afternoon. Mixing will be limited today (south-southwest winds of 5-10 mph) due to a strong subsidence inversion, but temperatures expected to warm nicely into the mid to upper 70`s. Cooler near the coast.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
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The stubborn upper low finally picks up speed and pushes northeast away from the area tonight as the ridge axis aligns along the Eastern Seaboard. Lingering moisture will keep some clouds along the coast, but clearing expected inland. Lows generally in the upper 50`s to low 60`s. Ridge axis slides offshore ahead of an approaching cold front Thursday. Increasing return flow and 850mb temps around +14 to +16C (around +1 standard deviation) result in warm (and dry) conditions with highs generally in the mid 80`s. Cooler along the coast. Plenty of sunshine expected. Aforementioned cold front reaches the central Appalachians late Thursday as an upper level trough lifts from the Ohio Valley over the eastern Great Lakes region. Limited moisture return expected ahead of the front as the best dynamics lift well north of the Mid-Atlantic. The cold front progged to not make it over the mountains Thursday night as southwest flow aloft prevails. Pressure falls along the lee side of the Appalachians will push a pre-frontal trough across the region Thursday night. Given modest theta-e advection and warm temperatures, guidance does indicated some marginal instability across the Piedmont Thursday evening. However, temperatures aloft remain warm. Given the limitations, have only slight chance to low end chance POPs Thursday evening. Better moisture progged across the eastern portion of the local area late Thursday night, so have 30-40% POPs for scattered showers and possibly a thunderstorm. Deepest moisture pushes offshore Friday morning, with only a slight chance POP across the far southeast. Sky becomes mostly sunny to partly sunny Friday afternoon. Another warm day in store, with highs in the mid (possibly upper) 80`s. Cooler near the coast.
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&& .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Temperatures are expected to remain well above normal through the weekend as an upper level ridge remains anchored over the Ern Conus. 850mb temperatures ~18C will support highs in the upper 80s to around 90 Saturday (75-80F at the immediate coast) after morning lows in the mid/upper 60s. A weak front will knock high temperatures down a few degrees Sunday over the Ern Shore, with low 80s expected and mid/upper 70s at the immediate coast. Meanwhile, highs W of the Bay will once again be into the upper 80s. Aftn/evening chances for showers/tstms Saturday/Sunday will be low and mainly aob 20%. A cold front approaches from the W Monday. Forecast highs Monday are in the low/mid 80s after morning lows in the mid/upper 60s. 25/12z GFS/ECMWF/CMC support the best chc for showers/tstms very late Monday aftn into Monday evening and shifting to the coast late Monday night. Temperatures trend back toward normal Tuesday with highs in the 70s. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... Latest surface analysis centers low pressure just offshore the Mid-Atlantic coast. The result is ongoing widespread IFR conditions over the region. VFR conditions currently observed across southeast Virginia into northeast North Carolina, but expect deteriorating conditions as the low slowly lifts northward. Area of light rain along the coast has reduced visibilities to MVFR. Surface winds have become northwest at or below 10 knots. IFR conditions prevail thru mid morning as the low lifts slowly northward. Light rain wraps around the low, mainly impacting the Northern Neck to Eastern Shore. Have kept mention of patchy fog over the Piedmont and Eastern Shore, but due to stratus and the upper low lifting over the region, expect areas of drizzle to persist through early-mid morning. Expect improving conditions mid to late morning inland as ceilings lift to MVFR and rain/drizzle/fog lift/dissipate. IFR conditions will be slow to improve KSBY as the low slowly lifts northward. Elsewhere, VFR conditions return with a generally broken sky. Surface winds generally out of the west at or below 10 knots. Low pressure lifts along the Northeast coast Thursday as high pressure/fair weather returns to the region. The next cold front stalls north of the region Thursday night/Friday, with only a chance of rain Thursday night. High pressure centers over the western Atlantic this weekend. && .MARINE...
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Marine dense fog advisory is in effect thru 7am for the coastal waters north of Parramore Island. Latest sfc analysis shows a weak pressure gradient over the region, with sfc low pressure centered just off the Delmarva coast. Winds avg 10-15 kt (or less) over the entire marine area and will be relatively light today, allowing flow to become onshore by late aftn at 10 Kt or less. Seas remain elevated at 6-8 ft north and 4-6 ft south and given the light winds have converted SCA headlines to Small Craft Advisory for hazardous seas, these lasting through early this evening S and into Thu morning N. Elsewhere, a relatively benign/decent boating day expected with waves 1-2 ft or less. The gradient becomes a bit stronger on Thu, with winds turning to the S and expected to avg around 15 kt with some higher gusts. Some residual swell around 9-10 sec and the increasing winds look to keep seas elevated/probably coming back up to 5 ft offshore and a SCA headline may be needed for coastal waters. Marginal SCA conditions possible for the Bay/Rivers Thu aftn/evening but overall would expect this to be below criteria for headlines given a very warm airmass (temps in 80s) over water temperatures in the 60s or cooler leading to less than optimal mixing. Waves will build to 2-3 ft in the Bay and 1-2 ft rivers. Similar conditions expected Fri/Sat as the warm weather and a general southerly flow persist. Some guidance depicting a backdoor cold front could shift winds to the NE for awhile for northern coastal waters by Sunday, but most places likely to stay south of this boundary.
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&& .TIDES/COASTAL FLOODING... Current tidal departures continue to average around 1.0 to 1.5 feet, with strong low pressure pushing up the Mid Atlc coast. With the high tidal anomalies and new moon tomorrow, expect many areas to reach minor flooding tonight. Have hoisted several coastal flood advisories and statements to account for this. Think this tide will have the highest water levels this week, but still cannot rule out some areas getting to minor again Wed/Wed night. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...Coastal Flood Advisory until 6 AM EDT early this morning for MDZ021>023. NC...None. VA...None. MARINE...Small Craft Advisory for hazardous seas until 10 PM EDT this evening for ANZ654. Small Craft Advisory for hazardous seas until 7 PM EDT this evening for ANZ656-658. Dense Fog Advisory until 7 AM EDT this morning for ANZ650-652. Small Craft Advisory for hazardous seas until 10 AM EDT Thursday for ANZ650-652.
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&& $$ SYNOPSIS...SAM NEAR TERM...SAM SHORT TERM...SAM LONG TERM...AJZ AVIATION...SAM MARINE...LKB TIDES/COASTAL FLOODING...

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