Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 151754 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1254 PM EST Sun Jan 15 2017 .SYNOPSIS... A weak frontal boundary will drift back south through much of the forecast area today, then lift back north Monday. Another frontal system will move into the region from the west Tuesday, then move slowly across the area Wednesday before finally move east toward the coast by Thursday. Several more days of cloudy, damp weather can be expected as a result of these frontal systems lingering across the region. && .NEAR TERM /THROUGH TONIGHT/... As of 1100 AM EST Sunday... Thin spots in the overcast will yield some sun through mid afternoon before thickening again this evening. Added solar insolation will boost temperatures a few degrees higher than previous forecast. Overall, not a bad afternoon as main rain threat will hold off until tonight. The wedge that was in place across most of the forecast area Saturday has lifted back to the north. Temperatures have surged into the mid and upper 50s across southwest VA and northwest NC early this morning, while temperatures were about 10 degrees cooler along the I-64 corridor. The retreat of the cooler air to the north will not be for long, however, as another cell of high pressure moves from the Ohio Valley toward New England. This is already evident in the LAPS analysis with northeast winds advancing westward from eastern VA. This wedge will encompass about the same area that the previous one did and hold in place overnight into the morning Monday before retreating back to the north. Max temperatures today will be tricky with the wedge affecting eastern areas fairly early while western areas, especially west of I-77 may not see the wedge at all and are already in the mid to upper 50s. In spite of the tease of sunshine, extensive cloud cover upstream of the forecast area will continue to overspread the area as the baroclinic zone oscillates about the region and a series of weak disturbances aloft drift east from a deep upper low in the southwest U.S. It appears that the best period of rain through this part of the forecast will occur later this evening into the overnight hours, especially north of the U.S. 460 corridor. Minimum temperatures Monday morning will be largely determined by the location of the wedge boundary, ranging from the mid 30s north to the upper 40s around Richlands which will never see the wedge. With temperatures remaining above freezing, there is no threat of freezing rain with tonights rain event. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... As of 315 AM EST Sunday... Another faint shortwave will be spilling east across the area to start Monday as surface high pressure translates down the Mid Atlantic coast by the end of the day. This should result in higher chance pops from west to east during the morning with rain tapering off during the afternoon, leaving only spotty coverage in the far west by evening. Locked in wedging could again result in cold enough deep valley temps for a spot or two of ice across Bath/Greenbrier counties early Monday, but very isolated if any occurs at this point, so likely wont mention. Otherwise strong warm advection aloft combined with the high sliding to the east should help slowly break down the wedge during Monday, but likely not enough to scour things out east of the Blue Ridge given clouds. Thus expecting a range in temps from the mild 50s to around 60 Interstate 77 corridor to only 40s from the Blue Ridge and points east. Surface high to finally exit offshore Monday night into Tuesday ahead of stronger shortwave ridging that will slide overhead in advance of the next weak cold front off to the west. Expect this to reduce shower chances Monday night with best lift still west of the mountains by early Tuesday. However the residual wedge will likely persist into Monday night out east before finally fading under even deeper warm advection on Tuesday as mixing increases. Thus lows still chilly with upper 30s/low 40s east to mid 40s west Monday night. Models differ a bit on timing with the arrival of the pre-frontal axis of showers Tuesday with a couple rounds of showers possible later Tuesday into Tuesday night as the front slows up a bit and waves ripple along the boundary. Latest 00z ECMWF remains faster with decent coverage west Tuesday morning, while most other guidance including ensembles take until afternoon to spill shower across the mountains. Since best support will be lifting out to the north while shortwave ridging holds in place, slowed down the onset of likely or higher pops to the western third of the area Tuesday, with higher pops lingering mountains, and chance east into Tuesday night. Highs Tuesday quite mild given 850 mb temps near +10C and decent mixing that despite cloud cover/showers should send highs well into the 50s if not warmer most spots. && .LONG TERM /THURSDAY THROUGH SATURDAY/... As of 345 PM EST Saturday... Surface front is forecast to cross the forecast area early Wednesday. Attm, models do not indicate much in the way of cool air behind the front, a few degrees drop at 850 mb, so once we dry out behind this feature Wednesday, the afternoon should be fairly nice with temperatures once again testing 60. Beyond Wednesday, the weather pattern still looks mild. A new cutoff low is forecast to take up residence within the southern stream over the southwestern CONUS with ridging over the southeast States and Gulf Coast. There are some model differences with respect to how far east the southern stream trough will progress next weekend. This results in timing differences with respect to precipitation. Per the mild pattern, there should not be any P-type issues for our forecast area with any precipitation falling in the form of rain. Forecast high temperatures will run about 10- 20 degrees above normal Wednesday through Saturday. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... As of 100 PM EST Sunday... Overall flying conditions will range from continued sub-VFR along the Blue Ridge and points west this morning to VFR/ocnl MVFR across the east. Should also see pockets of light drizzle over the mountains with ridges obscured attms. A stationary front extends from west to east across the southern Appalachians. Most of the Mid-Atlantic region resides north of this front with widespread cloud cover prevailing. This front is expected to gradually lift north tonight as a wave of low pressure ripples east along the front. This will result in lowering cigs and vsbys with areas of light rain developing after sunset. ifr are likely during the overnight period with pockets of lifr. The warm front will gradually lift north of the area by monday afternoon with cigs/vsbys trending back to MVFR. Extended Aviation Discussion... A baroclinic zone will remain anchored across the region sandwiched between a strong upper ridge over the southeast states and an active jet stream from the southwest U.S. into the northeast U.S. Thus, an unsettled, wet weather pattern is expected to remain in place Monday into Tuesday. The frontal boundary may lift north enough by Monday night for a brief period of mainly VFR, but a stronger front will arrive By Tuesday with more showers including widespread sub-VFR. Generally looking at MVFR much of the period, although periods of VFR as well as IFR-LIFR can be expected at times. Models remain uncertain with timing of another wave along a passing cold front during midweek. Some guidance showing another round of showers with sub-VFR on Wednesday with improving conditions Thursday. This while others slower with a break on Wednesday before moisture returns from the southwest Thursday afternoon into Thursday night. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RAB NEAR TERM...PM/RAB SHORT TERM...JH LONG TERM...JH/PM AVIATION...PM

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