Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 210129 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 929 PM EDT Sat May 20 2017 .SYNOPSIS...
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A cold front will continue to drift south across North Carolina tonight before lifting north as a warm front late Sunday. A cold front will move through the area from the west Monday. High pressure will briefly return Monday night before low pressure develops over the Carolinas Tuesday and moves northeast off the Delmarva into Wednesday. Upper level low pressure will then linger over the area into Friday.
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&& .NEAR TERM /THROUGH SUNDAY/...
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As of 9pm, a cold front is drifting into southern NC with 1032mb surface high pressure centered over northern Quebec and 1006mb surface low over northeastern Iowa. The warm sector of this low extends to the Gulf of Mexico with a plume of heavy thunderstorms extending into the Midwest. An onshore flow is across the area with clouds over the area except for lower southern MD. Expect low to mid 50s inland and upper 50s urban/nearshore. Onshore flow persists Sunday with the wedge firmly in place. Max temps upper 60s with rain approaching from the west late.
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&& .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
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The central CONUS low will lift to Lake Superior through Sunday where it will linger through Monday as it becomes a sprawling occluded low. The cold/occluded front will struggle to push east through the area Monday with prefrontal showers crossing the area Sunday night into Monday. Previous... Things will change Sunday night as a cold front reaches the Appalachians forcing the CAD-style cloud wedge to weaken but a line of showers/isolated thunderstorms to move through the area. Severe threat will be very low with this front as it will be coming through at night after a day with very little heating. Have upped PoPs to likely everywhere Sunday night. Precipitation chances will continue Monday as the cold front slowly works it way off the east coast. For the entire event QPF of 1/2" west to 1" east is possible. Precipitation should be ending in the west during the afternoon and east by evening. Improvement in sky condition is expected Monday night. Lows in the 50s except warmer in the cities and Lower Southern MD.
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&& .LONG TERM /TUESDAY THROUGH SATURDAY/...
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High pressure should keep the region dry Tuesday. The chance for rain showers return Tuesday night with a likelihood of rain showers Wednesday and Wednesday night as a broad storm system over the Ohio and Tennessee Valleys send pieces of energy our way from the southwest. The chance for rain showers or perhaps a rumble of thunder or two will linger Thursday and Thursday night as the main low pressure system decides to trek eastward toward the East Coast. Timing is uncertain as to how long it will take for the main low to move out of the area. There could be some leftover upper level energy overhead Friday. This could spawn a shower or two, mainly across the north and eastern areas. By Saturday, broad high pressure works its way into the region. Dry conditions and seasonable temperatures expected Saturday.
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&& .AVIATION /01Z SUNDAY THROUGH THURSDAY/...
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Cloud wedge hanging over the Mid-Atlantic tonight. Ceilings high MVFR to low VFR. Some improvement in cloud heights is expected Sunday ahead of a frontal boundary. Sunday night should be wet with multiple showers..continuing into Monday morning. A return to VFR is expected late Monday and Monday night. Vfr conditions Tuesday. Winds light and variable. Mvfr conditions Tuesday night. Winds light and variable. Ifr to lifr conditions possible Wednesday and Wednesday night. Winds south 5 to 10 knots Wednesday becoming light and variable Wednesday night.
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&& .MARINE...
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Easterly flow continues well into Sunday. Surge this evening in southern MD waters, easing after midnight when the SCA ends. Next possible SCA situation will be Sunday night ahead of a cold front and Monday behind the front. No marine hazards Tuesday through Wednesday night.
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&& .TIDES/COASTAL FLOODING... Easterly onshore flow has developed due to high pressure over eastern Canada. Flow turns southerly Sunday night as warm front lifts into the area. Water levels will gradually increase through Monday, with anomalies supporting elevated/minor coastal flooding at Annapolis, Straits Point, and DC by Sunday night. && .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 9 PM EDT this evening for ANZ532- 533-536-540>542. Small Craft Advisory until midnight EDT tonight for ANZ534-537- 543.
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&& $$ Update...Jackson Previous...Woody!/KLW

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