Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 231915 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 315 PM EDT Tue Oct 23 2018 .SYNOPSIS... A cold front will move southeast across the region to off the East Coast by Wednesday morning, followed by a large high pressure system. Low pressure that develops in the northern Gulf of Mexico late Wednesday will track across Florida Thursday then deepen as it moves northeast, reaching coastal North Carolina Saturday. && .NEAR TERM /THROUGH WEDNESDAY/... As of 315 PM EDT Tuesday... A cold front will drop southeast across the region this evening and push off the East coast tonight. Cooler air comes in behind the frontal boundary tonight and the air mass dries out above 850MB. Some low level moisture may get trapped on the western upslope side of the central Appalachians tonight. Gusty northwest winds are possible in the mountains through early this evening immediately behind a dry cold frontal passage. Winds could gust 25 to 30 mph before diminishing by late evening. In general, northwest winds will subside after sunset and become light northwest overnight. Low temperatures will range from around 30 degrees in the mountains to around 40 degrees in the piedmont. A large Canadian high will build into the region Wednesday. High temperatures Wednesday will vary from the mid 40s in the northwest mountains to the mid 60s into the piedmont. Confidence is average for all elements. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 315 PM EDT Tuesday... A short period of tranquil weather is expected during this time, as a progressive upper air pattern will be in place. With a large area of high pressure over the region Wednesday night/Thursday morning, generally went a couple of degrees below guidance for lows. Shortwave ridging Thursday will keep the area free from precipitation, but a large canopy of high/mid level clouds will blanket the area from west to east Thursday which will keep temps a couple of degrees cooler compared to Wednesday. A strengthening low level southerly jet will quickly advance moisture into our area from the south late Thursday night, and expect light precipitation to develop, especially in the south by dawn Friday. Confidence is low on this timing, as there will be a healthy amount of low level dry air to overcome initially. Soundings and SREF probs suggest some higher elevation locations may see a rain/snow mix initially when precip begins early Friday. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 315 PM EDT Tuesday... The long range models all paint a similar idea of deepening a surface low (thanks to the influence of a deepening negatively tilted upper trof in the eastern U.S.) that exits the Gulf of Mexico and quickly lifts northeast along the Atlantic seaboard Friday into Saturday. This will likely bring rain to much of the region Friday into early Saturday under a strongly diffluent upper air pattern. While PWAT values are currently not forecast to be especially high, ensemble forecast suggest a 30-40% chance of river flooding along the Dan River. A mention of flooding will be placed in the Hazardous Weather Outlook. As a result, bumped up winds and POPs during this period. With a healthy sfc wedge in place, went below guidance for high temps on Friday After this system departs, a dynamic upper level shortwave dives southeast on the western side of the eastern U.S. upper trof, helping to amplify this trof, keeping temperatures well below normal and bringing upslope precipitation through the early portion of next week. Model ensemble members still show uncertainty with the magnitude of the upper trof, but confidence is high that below normal temps will be in place during the latter half of the forecast period. Forecast soundings hint that a rain/snow mix is possible in the higher elevations Sunday and Monday mornings. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... As of 147 PM EDT Tuesday... VFR conditions will prevail through the taf period. High clouds across southern Virginia and the Carolinas will gradually move south this evening into tonight. A cold front will drop southeast across the region this afternoon into tonight. Behind the front, winds will become gusty from the northwest in the mountains and foothills of Virginia and North Carolina. Wind gusts up to 25 knots are possible. Winds will slacken after sunset and become light overnight. Models have some low level moisture forecast behind the front along the west slopes of the central Appalachians late tonight. KLWB has a low chance of having MVFR ceilings after midnight. VFR conditions are expected Wednesday. Wind will be northwest around 10 mph. Confidence is average for TAF elements. Extended Discussion... VFR conditions expected through Thursday. The next chance of rain and sub VFR conditions will be Friday and into the weekend with a low pressure system crossing the southeast United States and then moving up the Mid-Atlantic Coast. MVFR showers are possible in the west early next week. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/KK NEAR TERM...KK SHORT TERM...PH LONG TERM...PH AVIATION...AMS/KK

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