Area Forecast Discussion
Issued by NWS Blacksburg, VA

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007 FXUS61 KRNK 150459 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1159 PM EST Sat Jan 14 2017 .SYNOPSIS... A weak cold front has drifted south of the region and will remain south of the area tonight into Sunday and will drift back north of the area Monday. Meanwhile, a series of disturbances aloft will track over the region keeping clouds and periods of precipitation across the region for several days. Finally, a stronger cold front is slated to move through the region by the middle of next week. && .NEAR TERM /THROUGH SUNDAY/... As of 300 PM EST Saturday... Arctic high pressure to our north will slide east tonight into Sunday. The high center pushed colder air pushing into our region. The frontal boundary has moved south of us and was located across Georgia and South Carolina this afternoon. A wave of low pressure will ride east tonight into Sunday. Regional WSR-88d images showed an area of rain off to our west mainly north of the Ohio River. This feature will rotate east tonight into Sunday. Utilized a blend of the HRRR and Hiresw arw-east for this afternoon into tonight because they capture this precipitation best. Then, blended in the nam for pops overnight into Sunday. In general, the Models seem to focus more activity west in the Tennessee valley overnight/early Sunday. At any rate, there will likely be patchy of fog and drizzle when it is not raining with low level moisture. With a non diurnal temperature curve, low temperatures range from the lower 30s in the northwest Greenbrier county to the mid 50s in the southwest mountains. With temperatures close to freezing in western Greenbrier county, there is a slight chance for freezing rain late tonight into early Sunday morning. The low level wedge across the region Sunday morning will weaken as the flow turns more northwest behind a weak exiting wave offshore. This may result in some drying especially across central and eastern portions of the forecast area Sunday before another transient but weaker surface high starts to build in from the north. Another Mid level shortwave will rotate east returning precipitation to the west and spreadings east by late Sunday. High temperatures Sunday will vary from around 40 degrees in the northern mountains to the lower to mid 50s along the southern Blue Ridge mountains. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 330 PM EST Saturday... Split flow pattern over North America will persist through Tuesday. This will keep our forecast area pinned between the colder northern stream westerlies to our north and subtropical warmth along the Gulf Coast. Closed southern stream low over the southwestern CONUS will be the focus for pieces of short wave energy which will eject east, resulting in period lift along a wavy surface front which bisects the Mid-Atlantic from west to east, dividing the colder air associated with the northern stream from the warmer subtropical air to our south. Result will be abundant cloud cover with the potential for rain and/or drizzle. Highest potential for rain during this time frame will be Sunday night and again Tuesday night, with widely scattered showers in between. Sunday night, models indicate about a 6-8 hour period of isentropic lift promoting 60-80 percent chance of rain, the highest pops vicinity of the blue ridge where lift will be maximized from the easterly low level wind field. Can`t rule out an hour or two of freezing rain/drizzle early Monday morning at the highest elevations along the Blue Ridge (Peaks of Otter and points north along the Blue Ridge Parkway) where temperatures will test 32 degrees. Elsewhere, just looking at a cold rain. Surface front will get a nudged north Monday into Tuesday, so temperature trend Monday into Tuesday should be up, with steady or increasing temperatures, from 40s Monday, steady or rising Monday night (40s/50s), testing 60 on Tuesday. Closed low over the southwest is expected to eject northeast into the upper Mid-West by Wednesday. This will send a surface front east bound, this feature approaching our area Tuesday night. Convergence along the front will likely result in another period of rain or rain showers, beginning as early as Tuesday evening in the mountains, then spreading east across the forecast Tuesday night. && .LONG TERM /WEDNESDAY 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 /06Z SUNDAY THROUGH THURSDAY/... As of 1145 PM EST Saturday... Overall poor flying conditions will continue overnight as a wedge of high pressure starts to lock in along and east of the mountains. Low clouds with patchy light rain and drizzle will combine to produce IFR/LIFR cigs and MVFR/IFR vsbys at times in the mountains and MVFR to periods of VFR out east where cloud bases should remain higher and rainfall less under developing low level northwest flow. Pilots should prepare for mountain obscurations into Sunday. Medium to low confidence with cigs and vsbys through Sunday given varying conditions in and out of the wedge through the weekend. Spotty nature of fog and drizzle is also problematic. Higher confidences that east to southeast winds will prevail on Sunday. Another weak wave of low pressure will track along the remnant boundary by Sunday evening with potential for another round of light rain Sunday night. Also with warm advection aloft over the residual weakening low level wedge of cool air, dense fog also possible espcly along and west of the Blue Ridge where rain/clouds may diminish overnight. 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 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...KK NEAR TERM...KK SHORT TERM...PM LONG TERM...PM AVIATION...JH/KK/RCS is the U.S. government's official web portal to all federal, state and local government web resources and services.