Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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564 FXUS61 KRNK 180553 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 153 AM EDT Wed Sep 18 2024 .SYNOPSIS... Low pressure centered over the Carolinas today will drift slowly northeast tonight and through the overnight hours, staying on the east side of the southern Appalachians, which will keep a chance of rain in the area through tomorrow. The low is expected to weaken and move offshore Thursday and Friday, lowering the probability of precipitation areawide. Dry weather and seasonal temperatures are expected for Saturday. && .NEAR TERM /THROUGH TODAY/... As of 633 PM EDT Tuesday... No major changes have been made to our latest forecast. However, we have made a refinement to the most probable location of isolated thunderstorms within an area that will be more prone to convection. Areas near the VA/NC border generally east of I-77 have experienced some isolated thunderstorms, also in association with some locally heavier rainfall. This area of convection is expected to continue over the generally same region over the next few hours. This activity has prompted a Flood Advisory and a Flash Flood Warning for a portion of this area. Continue to monitor our latest advisories and/or warnings for updates for these situations, and also the potential for any new advisories and/or warnings. Have made minor changes to hourly temperatures, dew points, sky cover and wind speed/gusts to better reflect the latest conditions and expected trends through the evening hours. As of 200 PM EDT Tuesday Key message: - Isolated showers and mist look to continue areawide through Wednesday The occluded surface low over northern South Carolina will continue to fill in and remain quasi-stationary across the region into Wednesday. Scattered showers today are expected to transition to isolated showers with widespread light mist overnight tonight and continue for the majority of Wednesday. This is primarily due to occluded low remaining fairly stationary across southwestern North Carolina overnight tonight and into Wednesday. This will keep weak forcing for ascent coupled with PWATs in the 1.2-1.4 inch range in place across the region. 850mb winds look to continue to decrease significantly between this afternoon and Wednesday morning, which will similarly reduce the amount of upslope flow across the eastern peaks across the region. The only caveat for Wednesday is that some surface based instability of around 500-1000 J/Kg of SBCAPE could sneak into the Piedmont region tomorrow afternoon, which may enhance some of the isolated showers that develop to produce some heavier rainfall and lightning; however, confidence is not high at this time as several CAM solutions do not bring those aforementioned levels of instability into the region. Overall, the potential for any flooding threat is diminished for Wednesday as the combination of the weakening low, reduced forcing for ascent, and a weakening LLJ are expected across the region. With the occluded low in such close proximity to the the region, low stratus and overcast conditions are expected areawide on Wednesday. There will also be the potential for some isolated dense fog across portions of the New River and Greenbrier valleys. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... As of 215 PM EDT Tuesday... Key Messages: 1) Showers are likely to continue across the area as an upper level low lingers in the area through Friday. 2) The upper-low moves offshore late Friday, decreasing rain chances and causing temperatures to rise for the weekend. Rain chances continue for Wednesday night into Thursday, as an upper- level low will remain stalled over the area. Wednesday night will provide the best chance of rain in the period, with coverage decreasing on Thursday as the upper-low weakens and slides east. Cloudy and cool conditions will persist, with elevated winds winding down by Thursday. Temperatures will remain slightly below to near normal, with highs mainly in the 70s with higher elevations in the 60s. By Friday, the upper-low begins to move offshore into the Atlantic, with shower chances lowering throughout the day as skies clear out. This will allow temperatures to increase, with highs reaching the low 80s in the piedmont locations. The Ensemble Situational Awareness Table generally keeps QPF totals for Thursday and Friday under 0.25 inches across the CWA. High pressure begins to move back into the region, with dry weather expected heading into the weekend. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 215 PM EDT Tuesday... Key Messages: 1) Drier weather returns for the weekend, as high pressure builds in with a wedge that may keep temperatures just below normal next week. 2) There is a chance that rain returns early next week, but there is low confidence in this due to model disagreement. This weekend will see high pressure begin to dominate the region once again, drying things out with high temperatures in the 70s to around 80 expected on Saturday. This high pressure over New England will begin to wedge in the area on Sunday, which will cool temperatures to slightly below normal and increase cloud cover in the area. Highs will generally be in the low 70s with low temperatures in the 50s. Late Monday, there is a chance for rain to return to the region with a low pressure system that will move across the Plains into the Ohio River Valley. However, confidence is low due to model disagreement that the low will track into our area. A slight chance of showers is kept in the forecast next week, but regardless of rain chances, temperatures will remain near normal through the forecast period. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... As of 145 AM EDT Wednesday... Primarily LIFR to IFR ceilings across the region. This trend is expected to continue early this morning. The southern edge of the cloud shield around the upper low was approaching the Virginia/North Carolina border from the south. As the clouds clear out, dense fog, with LIFR visibility, was forming in the North Carolina piedmont. KDAN may have enough breaks in the clouds before 12Z/8AM for LIFR fog to develop. Ceilings will lift back to MVFR this afternoon. Clouds may also becoming scattered west of the Appalachians, including for a few hours at KBLF and KLWB. Stratus and fog will redevelop across the region this evening with LIFR ceilings and MVFR visibility by the 06Z/2AM end of the TAF forecast period. Winds will be from the east to northeast this morning, with a few gusts up to 20 knots. By this afternoon and evening, wind speeds will be less than 10 kts. Average confidence for ceiling, visibility, and wind. EXTENDED AVIATION OUTLOOK... Thursday and Friday less coverage of showers is expected. VFR conditions and dry weather is expected to return for Saturday and Sunday. && .EQUIPMENT... As of 135 AM EDT Wednesday... The Lynchburg ASOS (LYH) has been repaired. All data can now be transmitted. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...DS/EB SHORT TERM...JCB LONG TERM...JCB AVIATION...AMS/DS EQUIPMENT...AS/WP