Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 160135 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 935 PM EDT Sun Oct 15 2017 .SYNOPSIS... Low pressure over the Great Lakes will push a strong cold front through the area tonight. High pressure follows the front for the rest of the week. && .NEAR TERM /THROUGH MONDAY/...
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As of 930 PM EDT Sunday... Cold front will cross the forecast area overnight. At 2100 the front was along the western slopes of the Appalachians. It should be through BLF/LWB by 11PM, then to along the Blue Ridge between Midnight-1A, and across the foothills and piedmont between 1A and 4AM, exiting the CWA before sunrise. Typical of Fall fronts, expect falling temperatures/dewpoints and winds shifting to the northwest. Northwest low level jet of 30 to 35 knots noted behind the front along with 5-6 MB/6hr so will result in breezy conditions, especially across the higher elevations and just lee of the Blue Ridge. Strong cold air advection is forecast behind the front tonight with 850MB temperatures dropping into the +4 to +12 range by Monday morning. Actual low temperatures tonight will range from around 40 degrees in the mountains to the upper 50s in the piedmont. Rain showers associated with the front will be brief, amounts generally a tenth of an inch or less. Upwards of a quarter of an inch is possible across the higher terrain of southeast WV. Cold advection and upslope flow will lead to persistent low level clouds and a few lingering showers in the west into early Monday. In general however, showers will taper off Monday morning as the cold front pushes into the Atlantic ocean. The center of the 500 mb trough axis will swing across our area Monday afternoon into Monday night. High pressure in the Ohio Valley will build southeast across our area by Monday night. High temperatures on Monday will vary from the upper 40s in the northwest mountains to the mid 60s in the Piedmont.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 325 PM EDT Sunday... A large area of Canadian high pressure will slowly drift across the region through the period as zonal flow aloft transitions to ridging later in the week. 850mb temperatures will reach their lowest point Monday, near 0C in the northern parts of the CWA to around +8C in the south, warming back into the +8C to +12C range by Wed. A very dry air mass will spread across the area underneath the increasingly vertically stacked area of high pressure surface and aloft. Mean 1000-500mb reach will fall into the 15-20% range through the period. No precipitation and little to no cloud cover is expected. The only real sensible weather concern during this time frame is the potential for frost Tuesday morning and to a lesser extent Wednesday morning. Tuesday morning will offer the best combination of clear skies, maximum radiational cooling, and the center of the cold air mass near the WV/VA border. Some of the deeper mountain valleys should drop into the upper 20s to lower 30s, such as Burke`s Garden and Lewisburg. This would not be unprecedented at all as Burke`s Garden fell into the upper 20s once back in September. Patchy to areas of frost can be expected in many of these same locations as well as others west of the Blue Ridge that fall into the mid 30s. There should be enough moisture in the ground from the Nate rainfall last week and the light rain expected Monday to support fairly good coverage of frost. Later shifts will need to consider issuing a Frost Advisory for Monday night and also evaluate whether or not a freeze warning is warranted in a few spots across the western mountains given that it is yet prior to the deadline of 10/25 in those areas. My current thinking is that freezing temperatures will not be widespread enough for a freeze watch/warning at this point. Patchy frost may be a concern again Wednesday morning in some of the typically colder, sheltered deep valleys, such as Burkes Garden again, or LWB and BCB. The surface high will be a tad further east by that time. Otherwise, look for temperatures about 5-degrees below normal warming to above normal once again by Thursday. The very dry air mass will allow for cool nights and mild afternoons with a good warmup from sunrise to afternoon on the order of 30+ degrees. Lows mostly in the 30s with highs in the 50s and 60s Tuesday rising to the 60s and 70s by Thursday. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 335 PM EDT Sunday... Strong, vertically stacked high pressure surface to aloft will be parked over the area through the weekend. Deep troughing in the western U.S. will teleconnect to a strong ridge in the east and support this pattern, which has been quite common during the last couple of months. The entire period is expected to be primarily cloud free and dry with unseasonably warm daytime temperatures and near normal nighttime temperatures early in the period trending toward much above normal by the weekend. Minimum temperatures Thursday will be mainly in the 40s rising to the 50s by the weekend. Maximum temperatures will start out in the 60s and 70s warming by the weekend into the 70s west to around 80 east. The next cold front to bring any chance for precipitation will approach early next week and as of now appears to have even less moisture associated with it than the current front. Hence, a long dry period expected for our region. && .AVIATION /01Z MONDAY THROUGH FRIDAY/...
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As of 930 PM EDT Sunday... MVFR ceilings and visibilities are anticipated overnight as a cold front moves from west to east across the Appalachians. A bkn line of showers will be associated with the front, which is forecast to cross BLF/LWB around 11PM...BCB/ROA around Midnight, then through LYH/DAN between 1A-4A. A wind shift will take place with the frontal passage, direction switching from SW to NW. Pressure rises behind the front will result in breezy conditions, winds remaining gusty during the day Monday. Pockets of IFR ceilings are possible Monday morning across the higher ridge crests and possibly impacting BLF. Guidance has shown good continuity with the timing of the front. Medium confidence in ceilings, visibilities and winds during the taf period. Extended Aviation Discussion... The cold front will head offshore on Monday night, which will allow conditions to improve to VFR by Tuesday. High pressure will return for the remainder of the week with good flying weather from Tuesday through Saturday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...KK/PM SHORT TERM...RAB LONG TERM...RAB AVIATION...PM

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