Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 270423 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1123 PM EST Sun Feb 26 2017 .SYNOPSIS... High pressure will cross the area overnight before passing offshore Monday morning. A warm front will lift northeast toward the region Monday night and Tuesday resulting in an increasing chance of light precipitation. By Wednesday and Thursday, low pressure tracking east out of the Great Lakes will drag a trailing strong cold front east across the eastern United States. && .NEAR TERM /THROUGH MONDAY/... As of 1115 PM EST Sunday... Making added downward adjustments to low temps given some of the deeper valleys already in the low/mid 20s with a few added hours of good radiational cooling to go per very dry dewpoints under light winds/clear skies. Latest satellite pics also show mid/high clouds to the west struggling to move east into the very dry air aloft seen on evening soundings. Thus appears models a bit fast to bring moisture east which should allow most to see little more than thin high clouds for a while longer until more of the mid cloud canopy arrives late. This cloudiness should finally put a lid on temp falls well after midnight so running with some steadying or rises in readings before daybreak espcly west. Otherwise lows ranging from 20-25 valleys and eastern outlying spots to low/mid 30s ridges before clouds increase. Could even see a few teens deeper valleys per current observations. Previous update as of 634 PM EST Sunday... High pressure centered over southeastern TN will remain in control through the evening. However, watching increasing mid /high-level cloudiness associated with a low-amplitude shortwave over central KS advect quickly eastward, its eastern extent now into central KY/OH. I therefore opted to increase sky cover, essentially a west-east increase in cloud cover beginning just before midnight in our far western zones and into the overnight hours elsewhere. However worth pointing out that this sky cover will be nothing more than mid- level altostratus at worst. What that will do is curb what should be strong radiational cooling, the strongest of which should take place in the next few hours now that the sun has gone down. Temps should then begin to stabilize. I did raise lows up 1-2 degrees based on an increase in sky cover but idea that ridges should stay comparatively milder to the lower valleys looks good. Previous near-term discussion issued at 220 PM follows... Cold high pressure will be centered over the region this evening, then drifts off the VA/NC coast Monday morning. Warm moist air from a disturbance tracking across the Tennessee Valley will bring thick mid level clouds to the area Monday morning. If isentropic lift can increase, a few mountain locations may see a few light showers for the morning commute. However, this moisture must overcome some very dry low level air which will limit precipitation to scattered sprinkle/flurries across southeastern West Virginia. Best lift moves north during the afternoon, but clouds likely to stick around into Monday night. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 320 PM EST Sunday... Warm front over the Gulf Coast states to lift north to the KY/TN area by Tuesday morning while high pressure retreats eastward well off the mid-Atlantic coast. Will see some in-situ damming possibly into Tuesday as clouds increase Monday night with an drizzly/light rain scenario expected. The low level wedge erodes Tuesday afternoon, but expect cloudiness to stick around with threat of showers moving in, as warm front lifts north. Some instability arrives toward the southern and central Appalachians in the afternoon, so not out of the question for a few thunderstorms mainly west of I-77. As we head into Tuesday night and Wednesday will see less coverage over the piedmont but strong sfc low works northeast across the midwest into teh Great Lakes. Very strong energy with this system in terms of winds, with cold front tracking from Illinois to Arkansas Wednesday morning to the mountains by late Wednesday afternoon. SPC highlighted our area for Wednesday with threat of squall line and mainly damaging winds. Given timing of the sfc front, not out of the question to have some severe winds around Wednesday afternoon/evening, as shear is good as are low level lapse rates. However, the question is thermodynamics and how much, if any sunshine we get. Think with strong southwest flow in the low levels the areas along/east of the Blue Ridge should break out in the sunshine, as temperatures soar into the mid-upper 70s. Will highlight svr thunderstorm threat in the HWO. The line races east of the forecast area by midnight with showers lingering in the east and upslope side of the west. The EC model favored as GFS is quicker, nonetheless even with EC its shifting things east of us overnight Wed night. Winds crank up overnight as well as strong cold air advection arrives along with 6 hr pressure rises of 6-8mb and 8h winds 40- 50kts. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 120 PM EST Sunday... Sharp cold front expected to be off the coast by Thursday morning with brisk and cold winds for Thursday, with some lingering moisture in the west for a few snow showers. We will see moisture erode by afternoon with a weak high pressure center moving across the mountains. On the heels of this is a northern stream front that moves across Friday morning. Appears moisture and lift will be further north of the forecast area, but some rain and snow showers could spill into the mountains of WV to the Alleghanys. Strong high pressure works in from the midwest for Saturday then shifts south across the southeast U.S for Sunday. After a period of cooler temperatures near to just below normal Thu-Sat, we will warm back up for Sunday. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... As of 1120 PM EST Sunday... VFR conditions the rule through most of the TAF period. West to east increase in BKN/OVC high clouds mainly after midnight, followed by more mid deck canopy toward daybreak into Monday afternoon when cigs should slowly lower. Winds to remain light overnight then turning more southerly at 5-12 knots on Monday. Extended Aviation Discussion... A warm front is expected to lift northeast toward the region Monday night into Tuesday before passing to the north on Wednesday. Continued moisture advection ahead of this boundary should cause cigs to slowly lower Monday night and perhaps reach MVFR levels in spots espcly southern/eastern sections by early Tuesday. This will also keep a threat of showers in place including periods of sub- VFR Tuesday into Wednesday. A cold front pushes east into the area Wednesday into Wednesday night with potential for more widespread MVFR/IFR in showers and thunderstorms. Strong northwest winds along with mountain sub- VFR in upslope low clouds and light precip will likely follow the front for much of Thursday. Expect downslope drying to return VFR to eastern locations by Thursday afternoon with this trend lingering across eastern sections through the end of the week. However another weak clipper area of low pressure looks to track just north of the region by Friday with possible mountain MVFR in at least upslope cloudiness, and possible light precipitation western ridges later Thursday night into Friday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/AMS NEAR TERM...AL/JH/RCS SHORT TERM...WP LONG TERM...WP AVIATION...AL/JH/RCS

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