Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 231526 AFDAKQ Area Forecast Discussion National Weather Service WAKEFIELD VA 1126 AM EDT Thu Mar 23 2017 .SYNOPSIS... High pressure prevails over the region today, sliding offshore tonight through Saturday. A gradual warming trend begins Friday into the upcoming weekend. Low pressure tracks across the region early next week. && .NEAR TERM /THROUGH TONIGHT/...
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High pressure settles over the region today as a broad, anomalous upper ridge over the central US builds eastward. Despite moderating heights and low level thicknesses, a light onshore flow and limited mixing will keep temperatures below normal. Highs struggle into the low to mid 40s along the coast and into the low 50s inland. Otherwise, a clear sky prevails. High pressure slides offshore tonight as winds become south to southwest. Dewpoints begin to moderate overnight thanks to modest return flow, but still cool with lows in the upper 20s to low 30s inland. Cooler over the Maryland Lower Eastern Shore as temperatures drop quickly into the mid 20s late this evening before light return flow warms temperatures into the low 30s around daybreak.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY/... Upper flow flattens Friday as an upper level low tracks into the central Plains. High pressure slides farther offshore, resulting in increasing return flow over the forecast area. Southwest winds increase to 15-20 mph with gusts of 25 to 30 mph. 850Mb temperatures warm to around +6 to +8C (~1 standard deviation). Have trended toward the warmest guidance Friday as thicknesses depict temperatures warming into the mid 60`s. A shortwave tracking across the northern Mid-Atlantic region will result in a partly cloudy sky, mostly across the northern half of the local area. Breezy southwest winds Friday afternoon mix dewpoints into the low to mid 30`s Friday afternoon, resulting in minimum relative humidity values as low as 30%. Mild Friday night as light return flow continues ahead of an approaching storm system. Lows generally in the upper 40`s to low 50`s. The upper low begins to weaken/fill Saturday, tracking into the lower Missouri River valley late. Associated area of low pressure also locates in the vicinity of northeast Missouri. A warm front will extend eastward over the northern Mid-Atlantic region as the cold front tracks into the lower Mississippi River Valley. The result will be ongoing return flow over the local area. 850Mb high pressure centers slides offshore, with better moisture return expected, but conditions remain dry thanks to ridging aloft (warm temperatures and a lack of forcing). Warm, with highs in the mid to possibly upper 70`s under a generally partly cloudy sky. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Medium range of the forecast period characterized by near to above normal temperatures, courtesy of arriving mid-level ridging aloft, and surface high pressure oriented just off the Mid Atlantic/Southeast Coast. Main weather features of note will be a series of mid/upper level troughs...bringing a few periods of scattered light precipitation over the weekend/early next week. The first of these disturbances traverses across the central/southern Plains on Saturday, dampening as it crosses E-NE into the Ohio Valley and Great Lakes on Sunday and into the northeast on Monday. This feature will allow for some isolated to scattered showers Sunday afternoon into early on Monday. QPF will be limited with this feature. Instability and weakening dynamics/forcing remain maximized well off to our N-NW, and will therefore maintain 40-60% POP over our western/NW tier for some sct to numerous showers Sunday evening into Monday morning, with lesser pops for more isolated showers across the SE coastal plain. Mild southerly flow will keep temps mild, with forecast highs in the upper 50s to 60s Northern Neck and Lower MD Eastern Shore...with upper 60s to low 70s inland for the weekend into early next week. For the middle of next week...attention turns to a pair of shortwaves. A second southern stream disturbance is expected to track east/northeastward from the CA coast...across the Plains and Mid-South Late Sat to early Monday. This system will continue to weaken as it pushes across the eastern third of the CONUS Monday through early Tuesday. Meanwhile, a northern stream system will drop from the PAC NW toward the northern plains early Monday, eventually reaching the Great Lakes by the middle of next week. Models are still split on the evolution of these systems. The 12z/22 ECMWF and 00z EC Ensembles remains quicker to dampen these features with the GFS/GEFS a bit stronger/more amplified. Taking a middle of the road approach remains the preference at this point, with the resultant blended solution allowing for continued mild weather Mon to Wed with at least a small chance for showers on Tuesday and Tuesday night. Shortwave ridging rebuilds behind this system for Wednesday. Highs remain mild through the period, with 50s and 60s over the Northern Neck of VA into MD, with highs well into the 60s to Mid 70s inland. Early morning lows mainly in the 40s to low 50s southern sections. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... High pressure/fair weather prevails over the region this morning. A few high clouds at or above 25k feet AGL are streaming over the region, with little aviation impact. Surface winds generally north to northeast at or below 10 knots. SKC conditions expected today as high pressure settles over the region. Winds become south to southeast this afternoon, remaining at or below 10 knots. OUTLOOK...High pressure/fair weather prevails through Saturday. A storm system approaches from the west on Sunday, with a good chance of showers late Sunday through Monday. && .MARINE... Sfc hi pressure starting to build into the region, with winds starting to diminish. Have cancelled the SCA headlines for Bay zones N of New pt Comfort, and extended them through 1pm for the lower Bay where NE winds of 15-20 kt will persist another 2-3 hrs. For the coastal waters, seas have fallen off to 3-4 ft across the N so the headlines N of Parramore Island have been cancelled. They remain in effect through 1 to 4 pm this aftn farther S (lingering the longest for NC waters where its still 6 ft at buoy 44100). Winds gradually shift more to the E by late today at 10-15 kt or less. Sfc hi pres remains off the coast tonight...w/ winds becoming SW Fri and lingering through Sat. Speeds increase to 15-20 knots by Fri afternoon as a storm system develops over the Midwest. The next front crosses the waters early next week...w/ relatively benign marine conditions expected over the weekend in SSW winds mainly aob 15 kt. Seas averaging 2-3 ft...waves 1-2 ft. && .EQUIPMENT...
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Radar KDOX is now fully operational.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 1 PM EDT this afternoon for ANZ632>634-654-656. Small Craft Advisory until 4 PM EDT this afternoon for ANZ658. && $$ SYNOPSIS...BMD/SAM NEAR TERM...SAM SHORT TERM...SAM LONG TERM...MAM AVIATION...SAM/LSA MARINE...ALB/LKB EQUIPMENT...BMD

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