Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 201744 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1244 PM EST Mon Nov 20 2017 .SYNOPSIS... High pressure over the Lower Mississippi valley will move east and off the southeast coast tonight. A cold front will move through the eastern United States Tuesday night, followed by high pressure on Wednesday and Thursday. Another cold front will cross the region this weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 934 AM EDT Monday...No major changes needed to the going forecast, with only small adjustments to temperatures and dewpoints to account for current observations and trends through the early afternoon hours. A crisp start with temperatures in the mid 20s to the mid 30s. Lots of sunshine expected today which should push highs into the 40s to mid 50s, perhaps even a few upper 50s in the northern NC Piedmont. Coolest readings in the lower 40s in northern Summers and western Greenbrier counties under a fresh light snowpack. Previous near-term discussion issued at 210 AM follows... Upper trough and colder air aloft over the northeast United States move east today. 500 mb pattern over the Mid Atlantic region gradually becomes southwest ahead of the next northern stream trough. Colder air at 850MB is retreating too. by Tuesday morning 850MB temperatures will be in the +6 to +8 range over southeast West Virginia, southwest Virginia and northwest North Carolina. At the surface high pressure moves from the Tennessee Valley to off the Carolina coast by this evening. Expect the high to be far enough offshore tonight that winds will slowly increase from the southwest over the ridges overnight. Even surface winds in the foothills and piedmont may not decouple. Clouds and moisture along the western slopes all below 850MB. Model show clearing before 9AM then little to no clouds for the rest of the day and tonight. Will be staying close to National Blend and bias corrected MAV for highs today and lows tonight. && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... As of 145 PM EST Monday... Shortwave ridging will slowly weaken Tuesday as surface high pressure slides offshore in advance of both northern/southern stream shortwaves within the split flow regime. These features still remain just out of phase with only a couple solutions pulling enough moisture north for showers Tuesday night as the southern surface low passes off the Carolinas. Since the latest ensembles show a few showers both across the east, and also northwest with the northern piece of energy will keep in some low pops in spots Tuesday night. High pressure following these systems to bring drier weather including a quick punch of cooler air on brief gusty winds Wednesday before the gradient diminishes by Wednesday night. We will see another short wave trough track a disturbance off the Carolina coast Thursday and Thursday night. Rain with this system will remain along the coast with only an increase in high clouds for the area. Highs mid 50s to lower 60 Tuesday before cooling back to 40s mountains and 50s east per cool advection Wednesday and Thursday. Cold air slow to come in Tuesday night with most areas staying above freezing (mid 30s to lower 40s). Temperatures fall into the 20s across the mountains and 30s east Wednesday and Thursday night. && .LONG TERM /FRIDAY THROUGH SUNDAY/... As of 200 PM EST Sunday... Overall upper troffiness to prevail through the period with reinforcing energy arriving next week that looks to carve out an even deeper 500 mb cold pool. Will see low pressure develop offshore the Carolinas later on Thanksgiving within split upper flow early on but appears too far offshore for any showers at this point. Otherwise should see mainly dry weather under weak high pressure and overall below seasonal temps until a strong cold front arrives Saturday. This front will again be followed by colder temperatures next Sunday similar to this weekend. Appears a few western rain showers possible ahead of the front Saturday night, followed by western snow showers early Sunday, but little more than low pops for now. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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As of 1243 PM EST Monday... High-confidence VFR conditions through the 18z TAF period. Broad surface high pressure continues to migrate eastward to our south, leading to a light northwest component roughly east of the Blue Ridge contrasting with a light west to southwest component. Expect a subtle backing to west-southwest in the Piedmont with all TAF sites eventually going to a southwesterly wind 3-5 kt by 00z Tuesday. Clear skies should support an eventual decoupled boundary layer and lighter wind flow by overnight. May have some pockets of low-level wind shear as 925-850 mb flow increases to around 35 kts by early-morning Tuesday associated with warm advection. Accompanying that will be an increase in high clouds from southwest to northeast and predominantly over our Piedmont/Southside counties. Still could see some marginal low-level wind shear into the morning hours but less confident on this so left out of the TAFs for now. Expect more variable cloudiness into Tuesday, with the greatest cloudiness to the south and east. This will mostly affect Danville with VFR mid- clouds. It`s not until after 18z Tuesday when degradation in ceilings then becomes a possibility at Danville. Southwest winds increase Tuesday to around 6-8 kts. Extended Discussion... Look for lowering ceilings along the southern Blue Ridge foothills in NC and into the Piedmont Tuesday afternoon into the evening. Though VFR ceilings should be common outside of these areas, MVFR bases appear possible at Danville Tuesday afternoon and evening, along with limited chances for light showers. High pressure then establishes itself for the Wednesday through Friday Thanksgiving period, with an expectation of good flying conditions for Thanksgiving travel in the RNK airspace. Next chance for sub-VFR conditions is with a cold front on Saturday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AL/AMS SHORT TERM...RCS LONG TERM...JH AVIATION...AL

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