Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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551 FXUS61 KRNK 160753 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 353 AM EDT Mon Sep 16 2024 .SYNOPSIS... Potential Tropical Cyclone Eight moves onshore today and drifts through the Carolinas through Wednesday bringing a prolonged period of rain to the area. A low probability of rain remains in the forecast through the end of the week as high pressure wedges down the Appalachians. && .NEAR TERM /THROUGH TONIGHT/... As of 245 AM EDT Monday... Key message: - Rain spreading in this afternoon and evening Increase in winds from the east through a deep layer brings moisture and lift to the area and therefore rain. Precipitable water values that will be advected in by late today and through tonight will be in the 1.5 to 2.2 range. Leaning to the 3KM NAM and WPC/NHC for the timing and location of Potential Tropical Cyclone Eight, as well as WPC for the precipitation location and amounts. Expecting a combination of isentropic lift, upper diffluence and strong upslope tonight. Variety of models showing the potential for localized pockets of heavier rainfall amounts along the southern Blue Ridge and a shadow effect resulting in lighter amounts through the Greenbrier Valley. Will be increasing probability of precipitation across the area tonight and wind speeds at higher elevations. Not planning on adding any thunder to the forecast as there is little to no instability. Little opportunity for heating today. Highs will again be below normal. No need to adjust much from NBM temperatures for maximum or minimum temperatures. && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... As of 345 AM EDT Monday... Key Messages: 1) Confidence is high for ongoing chances of showers due to the remnants of Potential Tropical Cyclone Eight. 2) A risk of flooding exists if there are repeated rounds of heavy downpours during the middle of the week. The remnant low from Potential Tropical Cyclone Eight will slowly wobble northwestward towards western North Carolina on Tuesday. The models have trended further southwestward with the track in recent runs, and the remnant low may stall somewhere close to the North Carolina and Tennessee border sometime on Wednesday. The lingering upper level low will be blocked by an upper level ridge building to the north. Of course, there are still some uncertainties regarding this track, but this solution appears to be the latest consensus. Rain bands may be the heaviest on Tuesday across the Mid Atlantic but should start to weaken towards Wednesday. Wind gusts up to 30 mph may be possible along the higher elevations on Tuesday morning but should weaken thereafter. Rainfall amounts still remain a challenge due to the changes in the track and the fact that a cool wedge of high pressure will have to be overcome on Tuesday. This wedge could limit rainfall amounts in some locations but also provide an easterly upslope enhancement across portions of the Blue Ridge. At the moment, it appears that the southern Blue Ridge should witness the highest total amounts with one to three inches and locally higher amounts possible. There may even be a hint of instability as the week progresses and the wedge weakens to spark a slight chance of thunderstorms. A risk of flooding is possible if there are repeated rounds of heavy rainfall during this time, but the dry antecedent conditions allow a good amount of room for some rainfall. Temperatures will remain below normal for this time of year. && .LONG TERM /FRIDAY THROUGH SUNDAY/... As of 345 AM EDT Monday... Key Messages: 1) Confidence is moderate for lower chances of showers. 2) Temperatures still remain near or slightly below normal. The upper level low resembling the remnants from Tropical Cyclone Eight will hover over the Mid Atlantic into Friday. Upper level ridging to the north will keep blocking the low and eventually start to shove it southward by the weekend. Rainfall chances should continue to lessen compared to earlier in the week but may not vanish completely. Meanwhile, another area of surface high pressure could build across the New England states and start another cool wedge against the eastern slopes of the Blue Ridge. Temperatures will likely stay near or slightly below normal and might trend further downward if the wedge strengthens in later model runs. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... As of 140 AM EDT Monday... Mostly VFR conditions across the area at this time, with a few areas of MVFR ceilings along the higher elevations of the southern Blue Ridge. Ceilings will gradually lower throughout the day as Potential Tropical Cyclone Eight moves slowly towards the Carolinas. Generally east to northeast winds today and tonight. Winds become gusty again this morning, gusts between 20 to 25 knots are possible for KDAN and KLYH, as well as the along the Blue Ridge. There may be too much cirrus for fog in the Greenbrier Valley early this morning. Left a potential for a couple of hours of MVFR fog in at KLWB. Light rain from the tropical system reaches the VA and NC Piedmont this afternoon but is more likely after 00Z/8PM. Forecast confidence is average for ceiling, visibility, and wind. EXTENDED AVIATION OUTLOOK... Periods of sub VFR conditions are possible through Thursday, as a low pressure system brings rain and clouds to the area through the midweek. Widespread rain continues into Tuesday A lower chance of rain remains in the area through rest of the week. && .EQUIPMENT... As of 145 PM EDT Sunday... The Lynchburg ASOS (LYH) is still experiencing data transmission issues, mainly at night. Please use caution when using data from this site, as some may be missing. Technicians continue to investigate the problem. No estimated date for return to full service at this time. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...PW LONG TERM...PW AVIATION...AMS/AS EQUIPMENT...AS/SH