Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 250734 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 334 AM EDT Mon Jul 25 2016 .SYNOPSIS...
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A cold front will approach from the northwest late tonight. This front may stall across the region during the middle of the week. Another cold front is expected at the end of the week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A cold front is located across the Mid-West this morning. Other than that, little in the way of any surface features across the Mid- Atlantic. A warm and humid airmass is in place and a pop-up shower and thunderstorm is possible as elevated instability is present across the region this morning. Two hazards are expected today...heat and scattered strong thunderstorms. Warm air advection in the mid-levels will allow surface temperatures to climb into the mid-upper 90s with a few spots around the I-95 corridor getting near or hitting 100. High moisture content will lead to heat indices between 105-109 across much of the Mid-Atlantic with the exception of higher elevations and the Shenandoah Valley. A heat advisory is in effect from noon to 8pm today. The second hazard is for severe thunderstorms mainly along and north of U.S. Highway 50. As the cold front tracks east into the Ohio Valley today a shortwave trough will also approach the Mid- Atlantic region this afternoon. Instability is expected to increase to 2-3k j/kg with higher amounts across the northern half of the outlook area. Scattered thunderstorms are expected to form around 12pm-1pm today along and west of the Blue Ridge Mtns and track eastward. Ahead of the shortwave trough...wind field will increase mainly across OH/NY/PA however areas near the md/pa border will likely see shear increasing to 20-25kts. The strongest storms are expected across the nrn half of the region into this evening. To sum everything up...scattered storms are expected to develop this afternoon across the Mid-Atlantic as well as ahead of the cold front and current line of thunderstorms across the Mid- West. Due to the heat and moisture...isolated strong to severe thunderstorms are expected. Damaging winds and heavy rain are the main threats in strong to severe storms. Localized flooding can not be ruled out through tonight. Activity will likely sag southward across the southern outlook area late this evening and overnight. It should diminish some but thunderstorms are still likely overnight.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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The cold front will be near the Mid-Atlantic Tuesday morning. Light northerly winds will give some relief to the heat and humidity however temps will still reach the low to mid 90s and indices into the upper 90s to near 100 Tuesday afternoon. Showers and thunderstorms are likely mainly across the southern half of the outlook area Tuesday afternoon and evening. Coverage seems to be isolated however confidence is low at this time due to the stalled frontal boundary. The front will be near the Mid-Atlantic through Wednesday night. Showers and thunderstorms can not be ruled out through this period. Light w-nw flow aloft will keep heat and humidity down however still be above normal for late July. Uncertainity exists for coverage and threat level of thunderstorms Wed-Wed night.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/... A front will meander across the area through the end of the work week keeping the risk of t-storms Thu and Fri. With front stalled out across the area, we could see multiple rounds of convection with heavy rain becoming a bigger threat. It will still be hot and humid with temperatures in the mid 90s and heat indices at or above 100F. By the weekend, guidance shows a low pressure center developing off of the Delaware coast and moving northeast away from the coast with front clearing the fcst area and weak high pressure building in bringing lower humidities but with temps still around 90F. && .AVIATION /08Z MONDAY THROUGH FRIDAY/...
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VFR conditions expected this morning however a rogue thunderstorm is possible. More thunderstorms are expected this afternoon and evening and may impact the terminals. Some storms may be strong with gusty winds and heavy rain. Sub-vfr conditions expected in activity. The chance for thunderstorms persists through Wednesday as a frontal boundary stalls across the region.
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&& .MARINE...
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Overall winds expected to be 10-15kts today and tonight. A brief surge of SW winds ahead of a cold front is possible across the southern Chesapeake Bay late tonight and will need to be monitored. Showers and thunderstorms are possible this morning as well as today and tonight as a hot and humid airmass stays in places. Coverage will increase this evening and overnight as thunderstorms track eastward. Some storms may be strong to severe resulting in gusty winds. SMWs will be likely through Tuesday morning. A cold front will move through the waters Tuesday morning and winds will become nrly behind it. Showers and thunderstorms are possible Tuesday afternoon mainly across the southern waters and again on Wednesday.
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&& .CLIMATE... New record highs are likely today at DCA and IAD. Here are the record highs today, DCA...100 in 1930...79 in 1965 BWI...100 in 2010...77 in 1887 IAD... 98 in 2010...76 in 1965 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Heat Advisory from noon today to 8 PM EDT this evening for DCZ001. MD...Heat Advisory from noon today to 8 PM EDT this evening for MDZ003>006-011-013-014-016>018-503>508. VA...Heat Advisory from noon today to 8 PM EDT this evening for VAZ028-030-031-036>040-050>057-501-502-505-506. WV...Heat Advisory from noon today to 8 PM EDT this evening for WVZ052-053. MARINE...None. && $$ SYNOPSIS...LFR NEAR TERM...HAS SHORT TERM...HAS LONG TERM...LFR AVIATION...HAS/LFR MARINE...HAS/LFR CLIMATE...LFR

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