Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 162322 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 722 PM EDT Wed May 16 2018 .SYNOPSIS...
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A weak front across the region will remain about stationary through the end of the week. Low pressure lifting north into the Tennessee Valley will combine with the stalled boundary to bring periodic rounds of showers and storms into the weekend.
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&& .NEAR TERM /THROUGH THURSDAY/... As of 400 PM EDT Wednesday... The main focus through Thursday will be quasi-stationary front to our north and subtropical low lifting north into the southern Appalachians from the eastern Gulf of Mexico. Airmass south of the front and covering the entire southeast CONUS is more indicative of August as opposed to May with PWATs 2 standard deviations above normal. As such, showers and thunderstorms which occur within this environment will be very rain efficient. For our forecast area, anticipate numerous to widespread showers. CAPE has been limited to generally 1000 j/kg or less, so nothing severe, but lack of a cap has allowed for showers to bubble up all over the CWA... more of a shotgun pattern but nothing organized. Since the front is well north of the area, not much to focus the heavy rain, so no need for a flood watch attm, but may need to consider possibility of headline pending track of subtropical low as it lifts north into the southern Appalachians Thursday. Until then will entertain occasional showers with embedded thunderstorms with brief heavy downpours. Temperatures/dewpoints will remain summerlike with overnight lows above 60 coinciding with the August-like dewpoints. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 340 AM EDT Wednesday... The portion of the forecast is continuing to offer wet conditions across the region. From Thursday night through Saturday, an upper level area of low pressure will make gradual progress from western TN to Wisconsin. Saturday night, the low will open into a wave and start to be transported eastward as it reaches the northern jet. Its associated trough axis will still be extending south into eastern KY. This trough axis will cross our region Saturday night. On the east side of this low/trough, southerly, moisture-rich flow of air will be streaming across our area with its origins off the eastern Gulf of Mexico. It will be this moisture that will allow for a very generous coverage of moderate to heavy rain showers to cross our region during this time period, along with some isolated to scattered thunderstorms, especially during the late afternoon and evening hours. We will be monitoring precipitation patterns and amounts as we progress into this time period. This will help us gauge where and/or if any flood watches may need to be posted. The first time period of increased focus will be Thursday into Thursday night. WPC currently has posted a slight chance for excessive rainfall during this time period. Temperatures during this portion of the forecast are expected to average about five degrees above normal. Low will range from the low to mid 60s across the mountains with mid 60s to near 70 across the Piedmont. High temperatures are forecast in the the mid to upper 70s across the mountains with upper 70s to around 80 across the Piedmont. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... By Sunday, the upper low/trough that has been impacting our weather pattern the past several days, will be far enough north to be caught up by the northern jet, and heading eastward towards New England. This will return our region to a flow that initially will be predominately westerly, all while another baroclinic zone establishes itself along or near the Ohio River Valley by Monday evening. Concurrently, an upper high in the western Atlantic, east of GA/FA will hold fast, and anti-cyclonic flow around this feature will keep a decent fetch of moisture into our region at the lower levels. By Wednesday, the front to our north is expected to have trended farther south to over, or just north of our region. The result of the above scenario will be a weather pattern that will still have daily chances of showers and some thunderstorms. On average, chances will be greatest during the afternoon hours during the peak heating of the day. Chances will also on average increase by mid-week as the frontal boundary gets closer to, or overhead of, the area. Temperatures across the region will begin this portion of the forecast averaging five to ten degrees above normal. While a slight cooling trend is expected, by Wednesday, temperatures will still be averaging five degrees above normal. && .AVIATION /00Z THURSDAY THROUGH MONDAY/...
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As of 715 PM EDT Wednesday... Variable conditions will prevail into this evening with a mix of VFR to MVFR pending locations of heavier showers where IFR or worse could briefly occur espcly KDAN region under a passing heavier downpour. Expect showers to slowly wane with loss of heating but may be after midnight before coverage decreases to more isolated nature along/east of the Blue Ridge. Once the showers diminish, could also see areas of lower cigs/vsbys in stratus and some fog given the tropical air over the region. However uncertain to the extent of any fog overnight with stratus more likely at this point with widespread sub-VFR cigs possible overnight. Anticipating scattered to numerous showers/thunderstorms again on Thursday, but moreso during the afternoon as low pressure to the south approaches. However they are expected to lack organization...except perhaps across northern and western sections where will be closer to the residual front. Thus will maintain IFR/MVFR in low clouds to start Thursday and then transition to more prevailing showers with VCTS included for now. Winds will be light and variable, except in/near thunderstorms. .Extended Aviation Discussion... Continued period of showers and storms likely Thursday night and Friday as the wave lifts north perhaps resulting in more widespread showers overnight and then more diurnal nature to storms on Friday. As the weak low drifts north over the weekend, convective activity will become slightly less numerous and more scattered, but a better than normal chance for showers/thunderstorms and associated aviation issues will continue through at least Saturday with periods of sub-VFR possible. After more isolated storms on Sunday, appears another weak cold front may bring increasing coverage of showers and storms again on Monday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH NEAR TERM...PM SHORT TERM...DS LONG TERM...DS AVIATION...JH/PM

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