Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 221138 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 738 AM EDT SUN MAY 22 2016 .SYNOPSIS... A series of low pressure systems will lift northeast off the mid Atlantic and New England coasts through Tuesday as higher pressure builds slowly east from out of the Mississippi Valley. && .NEAR TERM /THROUGH TONIGHT/... As of 430 AM EDT Sunday... Several spokes of short wave energy rounding base of upper trof over the central and northern Appalachians will help to amplify upper flow and support development of vertically stacked H7-H5 low pressure that will drift south from out of upstate NY into eastern VA by this evening - then drift east to the coast by daybreak Monday. Mid-level lapse rates expected to steepen as daytime heating combines with slight cooling aloft with approach of upper low, once again supporting the redevelopment of scattered showers by late morning/early afternoon - with the threat continuing until at least mid- to late evening until thermodynamic support wanes. However, increasing northwesterly winds throughout the day will transport slightly cooler and drier air back into the area such that despite steepening mid level lapse rates, amount of convective available potential energy will be less than on Saturday. As a result, forecast soundings not particularly impressive in generating sufficient instability to warrant inclusion of thunder in the forecast - although an isolated rumble not entirely out of the question if insolation a bit greater than currently expected. Highest threat for precipitation today into tonight will likely be north of a line extending from near Bluefield WV to Danville VA, which will be closer to the deeper moisture and colder air aloft in vicinity of the approaching upper low. Downsloping winds and slightly warmer/drier air aloft over the NC foothills should help to minimize threat of precipitation in that area. Cool air advection and cloud cover in most areas should help to keep daytime highs lower than those experienced on Saturday - mainly mid 50s across the highest elevations, to around 70 across southside VA into north central NC. Overnight lows should be fairly uniform across the area - mainly mid to upper 40s in the mountains, to the lower 50s across the Piedmont. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... As of 320 PM EDT Saturday... The blocky upper pattern which has been prominent for the past several days will slowly be transitioning through the first part of next week. The closed upper low and associated cold pool aloft over the mid Atlantic region will be replaced by a broad low amplitude upper ridge and a Bermuda high at the surface by the middle of the week. This will bring a gradual improvement in our weather along with a significant warming trend. The influence of the upper low combined with diurnal instability will still be great enough to keep a good chance of showers across most of the region on Monday. By Tuesday as the ridging begins we will be down to just a slight chance of showers across the eastern portion of the area. However as the evolution of the pattern begins to pump steadily warmer and more moist air into the region the chances for showers and thunderstorms will start to increase again by Wednesday afternoon. We will start the week with very cool conditions as temperatures remain 5 to 10 degrees below normal with highs in the lower 70s east of the Blue Ridge and in the low to mid 60s to the west. However by Wednesday we will be getting a taste of summer with highs in the middle 80s east of the Ridge and in the mid 70s/around 80 to the west. && .LONG TERM /THURSDAY THROUGH SATURDAY/... As of 330 PM EDT Saturday... The upper level low tracks northeast of the area and off the New England coast Tuesday night. Behind this system high pressure and upper level ridge will bring very warm weather to the region with temperatures remaining above normal through Saturday. With the warmer weather comes a better chance for showers and thunderstorms each afternoon and evening. Storms do not look organized but pulse-like, tracking slowly from the southwest to the northeast. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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As of 735 AM EDT Sunday... Onset of daytime heating will allow ceilings and visibility to gradually improve back to VFR in most areas by mid-late morning. By afternoon, sufficient heating expected for sufficient vertical cloud development to support scattered showers, with most activity along and north of a line extending from KBLF to KDAN. Localized flight restrictions back into MVFR range, with some localized IFR restrictions in heavier showers, are possible. However, most areas outside of shower activity should experience mainly a broken ceiling in 4-6K foot AGL range. Surface gusts of 20 to 30 knots can be expected across the higher elevations during time of best surface heating today - with 10-20 knot gusts possible east of the Blue Ridge. Scattered showers expected to wane, and eventually end over the entire terminal forecast area tonight following loss of daytime heating. However, some isolated lingering showers/sprinkles may occur until after midnight along and east of a KLYH-KDAN line which will remain closer to an upper level low pressure system near the coast. Extended discussion... On Monday, winds will start to decrease as the center of the upper low slowly exits the region. Isolated showers with periodic sub-VFR conditions will still be possible during time of best daytime heating. However, by Monday night, and continuing into Wednesday, expect mainly VFR conditions to persist as high pressure settles into and over the area. On Thursday, we should start to see some potential for shower and thunderstorms to pop up during the heating of the day - mainly in the mountains. Late night/early morning fog with associated flight restrictions into the MVFR or IFR range may start to become an issue by midweek, most notably in the climatologically favored areas such as at/near KLWB and KBCB.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...WERT NEAR TERM...WERT SHORT TERM...MBS LONG TERM...RCS AVIATION...AMS/JH/WERT/WP

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