Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 060154 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 954 PM EDT Thu Aug 5 2021 .SYNOPSIS... High pressure remains over the area through much of tonight before sliding offshore Friday. Low pressure approaches from the southwest Friday night and tracks across the region Saturday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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As of 955 PM EDT Thursday... Current wx analysis shows a highly amplified ridge over the wrn Atlantic, with a shortwave trough tracking eastward over Pennsylvania/Maryland. Low pressure and its associated stationary boundary is offshore of the area, and weak high pressure is centered from Ohio to NC. Mostly clear skies continue to prevail over the vast majority of the area, with mostly cloudy skies over coastal NE NC. Temperatures in the upper 60s to around 70F as of 950 PM. Dry wx is expected to prevail through tonight with clearing skies as the aforementioned high settles over the area. With clear skies and very light winds, lows will fall into the lower 60s for most inland areas, with mid to upper 60s near the immediate coast. Some isolated upper 50s may be possible in typically cooler locations where the greatest radiational cooling occurs. In addition, may see patchy ground fog develop late across SE VA, NE NC, and inland portions of the MD Eastern Shore (away from the immediate coast...and especially in areas that saw a lot of rain earlier this week).
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... As of 345 PM EDT Thursday... High pressure slides offshore on Friday and the low-level flow will turn more to the ESE-SE by late in the day. Warmer but still fairly comfortable for early August as dew points are progged to only be a few degrees higher than today. Our next shortwave trough will be slowly tracking eastward across the TN Valley/Deep South on Friday. While the best deep-layer moisture will remain to our south through Friday evening, there is still a minimal chance (20-30%) of a shower or tstm over NE NC Friday afternoon/evening. The aforementioned shortwave trough approaches from the WSW Friday night and lifts NE across the area Saturday. This trough is progged to be rather strong for early August. A rather significant airmass change will occur Friday night into Saturday across much of the area, as deep-layer moisture will increase in advance of the shortwave trough. Dew points are progged to rise into the low/mid 70s across the SE half of the area by Saturday morning, with upper 60s/around 70F NW. PW values increase to 2.0-2.3" across the southeast half of the FA by 15-18z Saturday. Deterministic models continue to be in fairly good agreement with respect to the evolution of the trough, and are forecasting it to track from the Southeast and through the local area from Sat-Sat night, and then off the Mid-Atlantic coast by Sun aftn. The 12z/05 NAM and NAM Nest are a bit stronger with this feature and are showing a more amplified and northern track with a well defined surface low over the Mid- Atlantic (somewhat similar to the 00z/05 run of the GFS). Expect showers and tstms to move in from the south Friday night, and overspread most of the area (except for the far north) by midday Saturday. Pcpn exits the area from west to east from Sat evening through the first part of Saturday night, with just a few showers possible near the coast during the latter part of Saturday night. Have increased PoPs to likely across (roughly) the SE half of the forecast area, with high chc PoPs NW (highest PoPs are generally from 15z Sat-00z Sun). There is certainly a threat for localized flooding, especially across SE VA and NE NC (especially since a few inches of rain fell here earlier this week). The current QPF ranges from 0.1-0.25" N to 0.5-0.9" S, but there will likely be localized amounts of at least 1-2" within convection. WPC has a MRGL Risk for Excessive Rainfall across the SE half of the FA from 12z Sat-12z Sun. The lack of strong sfc heating/instability will limit the severe wx threat on Saturday. Lows Friday night range from the mid 60s NW to low 70s SE. Forecast highs Saturday range from the upper 70s to low 80s, but there is some uncertainty as clouds and more coverage of rainfall could hold highs in the low-mid 70s. Forecast lows generally range from the upper 60s to around 70F early Sunday morning. Clearing skies are expected on Sunday as the shortwave trough exits to the northeast. It will be mainly dry with a very low chc of an aftn shower/tstm across far srn and wrn portions of the area. Highs Sun in the mid 80s to near 90F. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 345 PM EDT Thursday... A more typical summertime pattern will return early next week as upper ridging builds from the Gulf coast to the SE CONUS. As the upper heights rise, so will the temperature and humidity. Expect high temperatures to rise into the low/mid 90s in most areas by the early to middle part of next week. Lows Sunday night/Monday morning range from the upper 60s to low 70s, with low/mid 70s expected toward the middle of next week. While isolated aftn/evening tstms are possible on Monday and Tuesday, most areas will be dry as there is little in the way of lift for any organized convection. By Wednesday/Thursday, the global models continue to forecast a couple of shortwave troughs to track across the Great Lakes, resulting in minor height falls across the Mid- Atlantic. Will show increasing PoPs (to 20-40%) for mainly aftn/evening tstms across the area on Wed/Thu. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... As of 745 PM EDT Thursday... VFR conditions are expected to prevail at all of the terminals through much of the 00z TAF period. FEW to SCT CU NW of RIC should diminish over the next few hours, giving way to SKC conditions or high clouds through the night. ECG has the greatest chance of high clouds late in the night as cloud cover increases from S to N. Otherwise, patchy areas of ground fog may develop late tonight into early Fri morning across SE VA, NE NC, and around SBY with occasional drops to MVFR VIS possible. Cloud cover increases from S to N Fri with MVFR CIGs possible near ECG by the end of the 00z taf period. However, confidence is too low in the MVFR CIGs reaching ECG to reflect in the tafs at this time. Winds become light and variable overnight as high pressure builds across the region. Winds eventually shift to E at ORF/PHF/ECG and SE at RIC/SBY Fri at 5-10 kt. Outlook...High pressure moves offshore late Friday. An area of low pressure tracks across the region Saturday bringing the potential for showers and degraded flight conditions. An upper ridge builds over the area Sunday and Monday with mainly dry and VFR conditions expected. && .MARINE... As of 945 PM EDT Thursday... Extremely quiet on the water tonight as weak high pressure is along the coast with a weak low near Charleston, SC. A stationary front lingers just SE of the mid-Atlantic coast. Winds have been light this evening around 3 to 8 kt and generally out of the east. Seas have persisted around 3 ft in the coastal waters and less than one foot on the Bay. Seas overnight along the coast will average 2 to 4 feet with light winds. Onshore easterly flow increases some Friday afternoon as the low to the south shifts north and highs moves offshore. Easterly flow of around 10 kt maybe pushing 15 kt late in the day especially from Cape Charles south. Still a fair amount of uncertainty regarding the strength/location of an area of low pressure that is expected to develop and cross the waters Saturday/Saturday night. The 12z NAM remains the most robust with this system (thus bringing the potential for some SCA conditions) while the other models are weaker and a bit further east with the placement of the low. For now am keeping the winds below SCA criteria and generally have speeds of 10 to 15 knots Saturday afternoon into Saturday night, but could see wind speeds trend higher if the forecast shifts closer to the 12z NAM. Sunday and beyond still looks like a more typical summer pattern with southerly winds of 5 to 15 knots (with the usual diurnal shifts in wind speed/directions). Moderate rip current risk for all beaches Friday. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...AJZ/ERI NEAR TERM...ERI/RMM SHORT TERM...AJZ/ERI LONG TERM...AJZ/ERI AVIATION...RMM MARINE...AJB/JAO

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