Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 220837 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 437 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 /08Z SUNDAY THROUGH THURSDAY/... As of 150 AM EDT Sunday... Mainly MVFR flight conditions expected at most terminal forecast points overnight as gradually increasing upsloping winds maintain clouds over the mountains. Further east, weakness in the pressure gradient and influence of weak moist cool wedge should help to keep low level clouds trapped, where some flight restrictions into the ifr range are likely - most notably at/near Lynchburg and Danville. Persistent upper low will drop south over the area Sunday with the next round of shortwave energy producing the best coverage of showers across the north and east from late morning into the early evening. Expecting a faster improvement in conditions early Sunday as increasing northwest winds kick in and lower ceilings and visibilities rise. However, once daytime heating develops, will likely see ceilings fill back in with MVFR cloud bases - especially in upslope areas such as KBLF, and where any afternoon showers redevelop under the upper cold pool. Surface gusts of 20 to 30 kts can be expected across the mountains Sunday, with 10-20 kts possible east of the Blue Ridge. 850 mb winds are progged to increase to 25 to 40 kts, and gradually veer northwest to north. Extended discussion... On Monday, winds will start to decrease as the center of the upper low continues to exit the region. Isolated showers and with periodic sub-VFR conditions will still be possible, especially in the east, related to this feature. Monday night through Wednesday, expect mainly VFR conditions as high pressure settles offshore with southwest flow in place. By Thursday we should start to see some potential for shower and thunderstorms to pop during the heating of the day mainly in the mountains. Fog may start to become an issue by the mornings midweek, in the typical areas like KLWB and KBCB. && .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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