Area Forecast Discussion
Issued by NWS Sterling, VA

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784 FXUS61 KLWX 101855 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 255 PM EDT Mon Jun 10 2024 .SYNOPSIS...
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A supporting mid-level trough of low pressure will push across the region today. High pressure will build over the area tonight through midweek, leading to mostly dry conditions.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A pressure trough moving through the area will bring scattered to numerous showers and thunderstorms to the forecast area this afternoon and into the early evening. With limited CAPE, the threat for any storms becoming severe is low. The area with the highest chances of precipitation is along I-66 and then along and east of I-95 this evening. Precipitation chances linger through the overnight for those in the eastern portions of the area, but any thunder should dissipate after sunset with the loss of daytime heating. Dry conditions return late tonight for those west of I-95 with patchy fog west of the Blue Ridge. Overnight temperatures dip into the 50s for most with higher elevations dipping into the upper 40s. Metro areas will stay in the low 60s.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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A weak area of low pressure and surface trough located just off the east coast will lead to a slight chance of rain showers and a possible rumble of thunder Tuesday in the easternmost portions of the forecast area. Those west of I-95 are expected to remain dry with sunny to mostly sunny skies. Dry conditions are expected areawide beginning Tuesday night as high pressure builds over the region. Dry conditions continue through Wednesday with mostly sunny skies. High temperatures on Tuesday will be in the 70s for most with those at higher elevations staying in the 60s. Overnight lows on Tuesday will dip into the 50s for most with those near the metro areas staying in the low 60s. On Wednesday, temperatures will be a few degrees warmer with highs in the low 80s for most. Overnight low temperatures will be in the upper 50s to low 60s.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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The warmest air mass of the year is set to build in the region towards the end of the week ahead of an approaching cold front that sweeps through on Friday. High pressure will then build across the region for the weekend, with dry and seasonably warm conditions expected. For Thursday, dry conditions are expected to continue as high pressure gradually moves offshore. Moisture return isn`t expected to be enough to bring thunderstorms into the forecast just yet. High temperatures will be very warm, reaching the low 90s for most. By Friday, the aforementioned cold front will approach and cross the region throughout the day. Ahead of that, southerly flow will funnel in warmer and somewhat more moist air into the region. Westerly flow aloft could help keep dew points on the lower end with mixing during the afternoon, so keeping dew points roughly around the low to mid 60s for now. What this will do though is lead to well above average temperatures. High temperatures Friday are likely in the mid to upper 90s for most. Heat Advisories may be needed, but could be difficult to high criteria if dew points struggle to rise higher than the low 60s as previously mentioned. Now, some guidance does bring dew points more into the mid-upper 60s, which could change the game a bit. Should we get into the 90s with dew points into the mid-upper 60s, the cold front may even spark a few thunderstorms during the afternoon. Should this occur, some storms could very well be severe. Thinking is that the best chance for this would be along a westward propagating Bay Breeze. Dew points are likely to be enhanced right along the Chesapeake Bay, so could see a localized favorable environment for thunderstorms to develop. Further west, finding it hard to see convection firing along the cold front itself, as dew points just seem like they are going to be too low, thus CAPE would be nearly non-existent. Carrying 20 POPs across most of the area, even west of I-95, as it is a very low likelihood event, but certainly can`t rule it out at this point. Have decided to up POPs around 30 percent right around the Chesapeake Bay to account for the localized higher likelihood mentioned previously along the Bay Breeze. The weekend looks to be dry, as ridging aloft takes hold of the region in the wake of the aforementioned cold front. Highs will generally be slightly above average, reaching the upper 80s. Humidity levels should be tolerable with dew points in the 50s.
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&& .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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VFR conditions are expected at all terminals through Wednesday with winds remaining light out of the northwest. As of 2PM today, all terminals are gusting up to 20 knots as a pressure trough pivots over the area. Gusts are expected to diminish around 6PM at all terminals with the loss of daytime heating. Winds go light and variable tonight and are expected to remain light, out of the north/northwest through Wednesday. As the pressure trough pivots overhead, isolated showers and a possible rumble of thunder are possible. Greatest chances are for KIAD and KDCA so included VCSH for this evening. Can`t rule it out at other terminals but confidence is too low on location of precipitation. Dry conditions return Tuesday evening and persist through Wednesday. VFR conditions are expected on Thursday and likely even into Friday. However, an isolated thunderstorm cannot be ruled out at any of the terminals Friday afternoon. Better chances could occur at DCA, BWI, and MTN where thunderstorm chances are a bit higher. If storms move over a particular terminal, brief VSBY reductions would occur.
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&& .MARINE...
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Small Craft Advisories are in effect until 6PM this evening with gusts up to 25 knots expected. Winds diminish this evening with the loss of daytime heating with northerly/northwesterly winds remaining below SCA criteria through Wednesday. An extended period of south-southwesterly winds is likely for Thursday through much of Friday. Some southerly channeling effects are evident in the model output which could support some advisory- caliber winds Thursday and Friday afternoon/evening. A chance for showers and thunderstorms returns to the waters late Friday with a cold front, which could necessitate some SMWs should storms develop.
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&& .TIDES/COASTAL FLOODING...
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Some of the more sensitive tidal sites start to near (or reach) Action during the higher of the high tide cycles by Tuesday morning with snapback occurring. However, no coastal flooding is anticipated through Thursday.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ530>543.
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&& $$ SYNOPSIS...AVS NEAR TERM...AVS SHORT TERM...AVS LONG TERM...CJL AVIATION...AVS/CJL MARINE...AVS/CJL TIDES/COASTAL FLOODING...BRO/AVS