Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 130727 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 327 AM EDT Wed Mar 13 2024 .SYNOPSIS...
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Surface high pressure will continue to influence the Mid-Atlantic region over the next few days with well above normal temperatures and mostly dry conditions. A low pressure system will approach the area Friday, bringing increased chances for rain. Another low pressure system may impact the region Sunday into Monday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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The high pressure centered across the southeast CONUS is allowing for dry and warm conditions this morning with light winds. This will continue throughout the remainder of the day with an increase in scattered mid to high clouds thanks to a shortwave moving off to the north of the area. Do expect there to still be a good mix of sun and clouds throughout the day. With the airmass remaining dry, do expect the high temperatures to favor yesterdays observations and could exceed them by a degree or two in some areas. Went above the NBM 90th percentile with widespread low to mid 70s for the lower elevations and low 60s across the higher terrain. Skies clear out again tonight as the shortwave moves further away. Overnight lows will be in the 40s for most of the area with light winds continuing.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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Another mostly dry day is expected on Thursday with a mix of sun and clouds throughout the day. Dewpoints begin to rise slightly for the afternoon so do expect temperatures to favor a slight increase compared to today with mid to upper 70s expected across the lower elevations. Would not be surprised to see a few areas across central VA reach 80 degrees. The main exception for potential precipitation would be across the Allegheny Front as the low pressure system gets closer to the Ohio Valley later in the day on Thursday. The associated warm front will likely extended across PA by Thursday night, leading to well above average low temperatures for the overnight hours. Most areas will likely only drop down into the mid to upper 50s. Clouds are expected to become more abundant overnight as a more moist airmass begins to invade the Mid-Atlantic. The low pressure system will begin bringing impacts to the area on Friday. First, the area will likely remain in the warm sector and thus allow highs for the day to be similar to Thursday with mid to upper 70s expected across much of the area with 60s in the mountains. Most of the area will be mostly dry early Friday before the main precipitation shield moves in for the afternoon/evening hours. Some guidance has a few hundred joules of SBCAPE across the area, yielding the potential for a few thunderstorms on Friday. The system continues to look progressive in nature so QPF totals remain in the less than a quarter inch range, with the highest values the further west you go. Most of the precipitation should be out in the late overnight hours where lows will be in the upper 30s out west and upper 40s to low 50s closer to the waters with decreasing clouds.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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On the synoptic scale, a rex block persists across western North America while an amplified northern stream anchors much of the central to eastern U.S. Subtropical ridging becomes suppressed and mainly focuses over Florida into the Caribbean. Within this northern stream flow, one such wave will have already exited the Atlantic coast. In its wake, temperatures are forecast to cool some over the weekend after a lengthy period of mild weather. A much stronger longwave trough enters the picture late in the weekend and into early next week. Comprised of sub-522-dm mid-level heights near Hudson Bay, a plunge of colder air works its way into the Great Lakes region on Sunday. The associated cold front races eastward reaching the I-95 corridor by late Sunday. Some shower activity is possible as this system presses through. In its wake, the true surge of colder air enters the Mid-Atlantic region with falling temperatures to start off the work week. After a weekend with high temperatures mainly in the 60s, readings return to near to below normal. In addition to the cooler weather, gusty west to northwesterly winds will overspread the area. For both Monday and Tuesday, wind gusts could push up to 25 to 35 mph, locally a bit higher over mountain locales. This cold advection pattern is forecast to lower temperatures into the mid/upper 40s by Tuesday, with upper 20s to 30s over the higher terrain. Additionally, upslope enhanced snow showers are possible starting as early as late Sunday night. This continues the following couple of days given the cyclonic flow aloft. Downstream locations likely stay dry in this regime.
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&& .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
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VFR conditions will continue through Thursday. Winds will be light out of the west today and south or southwest Thursday. Only a few periods of mid/high level clouds are expected. By Friday, scattered showers and thunderstorms will be possible, especially for the afternoon and evening hours. Brief sub-VFR conditions will be possible at times on Friday. For the weekend, expect mainly VFR conditions at the area TAF sites. A strong cold front does enter the equation Sunday evening and into the night. Some showers may accompany this system with brief restrictions possible. Otherwise, expect a multitude of wind shifts over the weekend. Initial northwesterly flow turns more variable the second half of Saturday. This eventually leads to a southerly flow regime by late Saturday before the next cold front brings a return to west-northwesterlies by Sunday afternoon/evening. Some increase in gusts are possible as this front pushes through.
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&& .MARINE...
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No marine hazards are expected through the day on Thursday with light southerly winds expected. By Thursday night, a low pressure system will begin approaching the Mid-Atlantic and may bring SCA winds to the waters. Showers and isolated thunderstorms become possible during the day on Friday, an SMW is possible. Additionally, winds likely pick back up post-frontally Friday night and will likely warrant a SCA for most of the waters. Marine winds largely stay below Small Craft Advisory levels on Saturday. With a shift to southerlies, some channeling effects over the southern waters could near 18 to 20 knots on Saturday night. A strong cold front pushes through Sunday evening with some small craft potential late Sunday night. A better chance for such occurrences looms thereafter.
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&& .FIRE WEATHER...
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Light winds are expected today with humidity slightly increasing compared to Tuesday, although there will continue to be a warm and dry airmass. High and mid-level clouds will increase later today. Thursday will be warmer still but with further increases in RH with winds becoming southerly. A low pressure system will approach the area Friday and bring the next chance of rain.
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&& .TIDES/COASTAL FLOODING...
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Tidal anomalies are on the increase with lighter west winds in place, and that upward trend will continue through the end of the week. Some tidal sites may near minor flood stage Thursday and Friday as winds turn southerly ahead of the next low pressure system.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...ADM/ADS NEAR TERM...ADM SHORT TERM...ADM LONG TERM...BRO AVIATION...BRO/ADM MARINE...BRO/ADM FIRE WEATHER...ADM/DHOF/ADS TIDES/COASTAL FLOODING...DHOF/ADS

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