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Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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363 FXUS61 KRNK 142314 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 714 PM EDT Wed Aug 14 2024 .SYNOPSIS... High pressure will keep our weather mainly dry through Thursday. The next widespread chance for rain arrives toward the end of the week and the weekend, as a low pressure system approaches from the Ohio River Valley. && .NEAR TERM /THROUGH THURSDAY/... As of 700 PM EDT Wednesday... Key Message: Quiet night cooling off into the mid 50s to low 60s. No significant changes to the forecast for this update. We have had even less shower activity over the southern Blue Ridge than we have the past 2 nights, and isolated convective updrafts in Alleghany and Wilkes will completely diminish shortly. Temperatures in the 70s and 80s at 7 PM will drop quickly off into the 50s and low 60s by morning. A PWAT of 0.95" on this morning`s RNK sounding showed moisture mainly around 700mb. This PWAT is about 30% of normal for today per SPC sounding climatology, and one indication it is not very humid. Fog is possible overnight in mountain and river valleys as dew point depressions shrink. We will also see occasional cirrus in NW flow aloft. As of 200 PM EDT Wednesday... Key Message: Mainly dry. Afternoon Cu field may spawn an isolated shower otherwise expecting dry conditions to close out hump day. Trend after today will be for increasing moisture, but should sneak out one more fair weather day Thursday before showers/storms make a more pronounced impact to the forecast. In the interim, high pressure is centered to our north with a weak but dry northerly wind. Winds will become southerly Thursday afternoon as the high moves to our east...clockwise flow around the high providing transition to a warmer and moister wind direction. Temperatures through the near term will be close to normal. Patchy fog possible again late tonight and early Thursday favoring the rivers valleys. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 200 PM EDT Wednesday... Key Messages: 1. Showers and storms possible Friday and Saturday, highest chances in the afternoons and evening. 2. Near normal temperatures through the period. By Thursday night, a 500mb trough will be east of the area, while another trough approaches from the upper Midwest, and a ridge expanding over the southeastern US. The ridge aloft and high pressure at the surface will keep conditions dry through early Friday morning. A frontal system will track across the Great Lakes region through the end of the week, and the warm front will lift into the northern Mid Atlantic. Showers and storms are expected to be ongoing from the overnight period over the Ohio Valley associated with this system, so could see some early to mid morning activity as the front progresses eastward, though that activity will likely weaken upon reaching the mountains. By the afternoon, diurnal heating will help to destabilize the atmosphere, and coverage of showers and storms will increase for the afternoon and evening hours. There is a marginal risk of any storms reaching severe criteria, mostly west of the Blue Ridge, as 0-6km shear increases with the approach of the cold front. Showers and storms could continue overnight into Saturday morning, but will more likely wane with the loss of daytime heating. The slow moving cold will spark additional shower and thunderstorm development Saturday afternoon and evening. The front is expected to finally exit to the east by Saturday night, and activity will diminish Saturday night. Heavy rain is possible with any showers and storms both Friday and Saturday, as forecast PWATs near the 90th percentile relative to climatology, in the 1.5 to 2.0 inch range. Temperatures will rise a few degrees by Saturday as south/southwesterly flow advects moisture northward, and dewpoints will be on the rise, so expect more warmer humid conditions by the end of the work week. Highs may approach 90 in the VA Southside and Piedmont, and Roanoke Valley by Saturday. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 200 PM EDT Wednesday... Key Messages: 1. Chances of showers and thunderstorms continue through the beginning of the work week. 2. Temperatures right around normal. Troughing aloft persists over the eastern US through the second half of the weekend and into the work week. This will keep chances of showers and thunderstorms in the forecast through Monday. However, with no appreciable forcing mechanism, like a front, most of the activity will be diurnal and isolated to scattered in nature, and not likely to be severe. That being said, still too far out in the forecast for mesoscale details to be resolved, so any severe potential is uncertain at this time. By midweek, the trough will finally push to the east, as a large ridge over the southern US starts to expand farther east, and surface high pressure builds over the area. This will bring about a return of dry weather to the area for the mid to late week. Temperatures will be around seasonal normals, with mid 80s in the east, and mid to upper 70s in the west. Lows will be in the mid to upper 60s, but could dip into the mid 50s for the typical cool spots on the clearer nights after the start of the week. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As 700 PM EDT Wednesday... VFR conditions are expected at all terminals through most of the TAF period. SCT-BKN CU continues to diminish this afternoon in mainly dry conditions. Some passing cirrus is expected overnight, along with fog in mountain and river valleys. Fog most likely at LWB/BCB/DAN, dissipating by 14Z/10AM Thursday. Winds will remain light from the east to northeast. .EXTENDED AVIATION OUTLOOK... Thursday afternoon should remain dry with VFR conditions across the Mid Atlantic as high pressure maintains control. However, as high pressure moves offshore on Thursday night, clouds will increase from the west due to an approaching cold front. This front should bring a good chance of showers and thunderstorms along with potential MVFR/IFR ceilings during Friday and Saturday. Thunder chances may lower by Sunday as more stable air arrives behind the cold front. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...PM/SH SHORT TERM...AS LONG TERM...AS AVIATION...PM/SH