Area Forecast Discussion
Issued by NWS Sterling, VA

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396 FXUS61 KLWX 131934 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 234 PM EST Fri Dec 13 2019 .SYNOPSIS...
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Low pressure will move north up the East Coast tonight and Saturday. High pressure will return briefly on Sunday before another system potentially affects the region Monday into Tuesday. Cold high pressure will then follow for the middle of next week.
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&& .NEAR TERM /THROUGH SATURDAY/...
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Rain continues for most areas along and east of the Blue Ridge Mountains. Temperatures have risen above freezing for most of our region but near to below freezing temperatures continue for portions of western Maryland, the eastern panhandle of West Virginia and northern Virginia. These freezing temps continue to erode and we expect most areas to be above freezing by 3pm with portions of western Maryland remaining below freezing through 5 pm. Freezing rain and drizzle will continue to be possible for parts of western Maryland, Northern Virginia, and eastern West Virginia. The threat for wintry precipitation has mostly diminished and remains focused to this afternoon. Temperatures should max out today in the upper 30s to low 40s. with overnight lows this evening in the 30s. Rain is expected to continue through early Saturday afternoon as the upper low moves northward over our region. General trend has the rain moving out of our region by Saturday evening sometime around 00Z. As the main upper low moves through our region this evening into early tomorrow, rain may become moderate at times which could lead to decreases in visibility especially over the higher elevations. Temperatures on Saturday will be warmer then today in the mid to upper 40s to low 50s. This indicates we are expecting mainly a rain threat on Saturday.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
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Rain will start to diminish after 18Z and be fully out of our region by 00Z Sunday other than some upslope induced rain and snow showers. A westerly flow will form as the surface low pressure system lifts to our northeast. The westerly flow will lead to upslope showers over the western parts of the Allegheny Mountain range with some these showers falling as snow. Currently we have potions of the elevations receiving up to a few inches of snow. The upslope induced showers should diminish by Sunday morning High pressure will briefly build over our region late Saturday and through Sunday. Should become mostly clear on Sunday with some mid to high level clouds lingering along the Allegheny Mountain range. Temperatures will be warmer in the 40s to low 50s during the day with cooler temps in the 30s for Sunday night. A warm front will lift through our region late Sunday into early Monday. The shield of precipitation associated with this boundary will start to affect our area late Sunday evening with outer portions of the DC metro near Sunrise on Monday. Areas north and west of the I-95 corridor may experience periods of wintry mix in the form of rain and snow with best areas for snow being northern Maryland, Norther Virginia and West Virginia. Any wintry mix will depend on the temperatures Monday morning and the timing of the precipitation.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/...
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Low pressure moving from the mid MS valley through the OH valley Sunday into Monday will bring another threat of overrunning precip. Some light mixed p-type is possible at onset, but with sfc and 850 mb low centers passing well northwest of the area, expect bulk of the precip to fall as rain with only light wintry precip possible. Cdfnt will cross the area Tue afternoon with rain/showers ending with frontal passage. Winds begin to increase Mon night from the SSW and then increase further on Tue from the NW as pres gradient tightens between low pressure offshore and building high pressure from the west. Think gales are possible, but wind advisory headlines appear unlikely at this time. Much quieter wx pattern sets up for the rest of next week but with more seasonable cool temperatures for mid to late Dec with highs in the 40s and lows in the 20s.
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&& .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
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Rain continues for all terminals leading to mainly IFR conditions with brief periods of LIFR restrictions. I believe all terminals will potentially experience periods of LIFR conditions but I didn`t feel confident on a specific time that LIFR conditions could occur. The best chance for LIFR restrictions will be when the moderate rain moves through our area overnight and I have tried to indicate that in the TAF`s with ceilings hovering near LIFR thresholds. Visibility will likely be restricted to IFR to MVFR during light to moderate rain. I believe the two areas that I have the highest confidence for LIFR conditions will be MRB and CHO terminals since both tend to restrict much easier. IFR conditions will likely continue through Saturday morning becoming more MVFR late Saturday morning and into the afternoon periods as the rain starts to taper off. VFR conditions are expected Saturday evening and through Sunday. More rain is expected late Sunday into Tuesday with some very light wintry precip possible at onset, but bulk of precip should be rain. Gusty winds Mon night and then windy Tue with gusts to 35 kt possible.
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&& .MARINE...
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Small Craft Craft advisories arent expected through Saturday morning. As the surface low pulls off to the north, winds will pick up over the waters. Small Craft Advisories will likely be needed for Saturday afternoon through Sunday afternoon. Small Craft Advzy conditions likely Monday afternoon and night with gales possible Tuesday. Continued SCA conditions likely through the middle of next week.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Winter Weather Advisory until 3 PM EST this afternoon for MDZ003-004. Winter Weather Advisory until 6 PM EST this evening for MDZ501- 502. VA...Winter Weather Advisory until 3 PM EST this afternoon for VAZ026>031-040-501-505-507. WV...Winter Weather Advisory until 3 PM EST this afternoon for WVZ050>053-055-501-502. Winter Weather Advisory until 6 PM EST this evening for WVZ503- 504. MARINE...None.
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&& $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...JMG LONG TERM...LFR/JMG AVIATION...LFR/JMG MARINE...LFR/JMG

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