Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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348 FXUS61 KRNK 250548 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 148 AM EDT Wed Sep 25 2024 .SYNOPSIS... A slow-moving frontal system will meander along the Ohio River Valley over the next several days, triggering rounds of showers and thunderstorm activity through much of the workweek. Helene is forecast to move northward from the Gulf of Mexico toward the end of the work week, and may bring more widespread rainfall to the region. && .NEAR TERM /THROUGH TONIGHT/... As of 130 AM EDT Wednesday... Key Messages: 1) Heavy rain and thunderstorms to continue through the early morning hours. 2) A lull in rainfall during the day, but will see an increase in rain again tonight across the mountains. Ongoing rain and thunderstorm activity this morning will continue through daybreak in association with a stalled surface front extended south from West Virginia into Western Virginia and then into the North Carolina Piedmont. Favorable upper divergence remains overhead as an upper low closes off over the middle Mississippi Valley. High ambient moisture continue to pool over the area, thus ongoing rain/storms this morning continue to be very efficient rain producers. Therefore, the threat for flooding continues this morning. CAM guidance suggests there will be a lull in rain/storms late this morning and into the afternoon hours as the stalled front lifts north again as a warm front. May even have some pockets of clearing and peeks of sun by the afternoon. Attention then turns to the mountains tonight from northwest North Carolina into far southwest Virginia as deep tropical moisture begins to be drawn north and interacts with a stalled front across the Tennessee Valley. A nearly unidirectional southerly flow up to 500mb directly from the tropics will result in bands of rain developing and repeatedly training from south to north over the same areas. Heavy rainfall could begin as early as tonight across the Carolina mountains and extend north into southwest Virginia. Confidence has increased enough that a Flood Watch will be introduced for this region. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Issued at 135 PM EDT Tue Sep 24 2024 Key Messages: 1: Outer bands of TS Helene will cause showers as early as Thursday 2: Heaviest and most widespread rainfall will be Friday and Friday PM Moisture convergence over a weak wedge will continue to cause showers and embedded storms Wednesday night. TS Helene will still be in the Gulf, but entering the influence of a closed 500mb low near the Arklatex and MS. This low will accelerate Helene quickly northward, going from the FL panhandle to western Carolina in the span of just 12 hours. This could place the outer bands of tropical moisture and rain in our NC counties as early as Thursday afternoon. Friday looks to be the most active day, with rain expected for most of the day throughout the CWA. Flooding will be a definite concern as we expect 3-4" along the southern Blue Ridge and in the High Country, and 1-3" across the remainder of the CWA. As always with banding in tropical systems, due to the nature of banding there could be higher amounts in localized areas. Flooding concerns will be exacerbated by the enhanced winds, particularly near and south of the NC/VA border. Above 3kft elevation, winds could gust up to 30kt. This will blow down early dead leaves, serving to clog up drains, culverts and sewers. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 200 PM EDT Tuesday... Key Messages: 1) Lingering moisture from Tropical Storm Helene will remain in the area through the forecast period, with showers possible each day. 2) High pressure wedges back into the region on Sunday, decreasing rain chances and keeping below average temperatures through midweek. As Tropical Storm Helene begins to dissipate over the Appalachian mountains early on Saturday, remnant moisture and breezy conditions will remain across the area. Rain chances decrease significantly on Saturday but remain possible. High temperatures will be in the 70s, with eastern piedmont locations around 80. For Sunday, surface high pressure over New England will begin to wedge back into the RNK CWA, pushing drier and cooler air southward. Residual moisture from Helene will continue to ride over top of this wedge, leading to light showers and cloudy conditions continuing into early next week. Due to the cloud cover and high pressure wedge, temperatures are expected to remain below normal beginning on Sunday. Highs will be in the 60s and 70s, with lows in the 50s to around 60 degrees through midweek. Winds also remain slightly elevated due to the wedge. There is some model disagreement with where the remnant low and associated moisture will go early next week. The Ensemble Situational Awareness Table continues to keep precipitable water values around 1.5 inches for early next week. Due to this, PoPs are kept modest through the forecast period, with showers possible each day. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... As of 145 AM EDT Wednesday... Poor flying conditions through daybreak with widespread IFR/LIFR across the area. A combination of low cigs/vsby, along with areas of heavy rain will continue through daybreak and may linger a few hours after sunrise. Should see some slight improvement during the late morning as rain begins to come to an end. However, sub-vfr cigs are still likely for the mountains throughout most of the day. A period of low end VFR for ROA/LYH/DAN possible mid/later afternoon. Rain and thunderstorms will increase again tonight along and west of the Blue Ridge, and especially for the North Carolina mountains and for southwest Virginia. Outside of the heavy rain, low cigs/vsby will result in another round of widespread IFR/LIFR late in the TAF period. EXTENDED AVIATION OUTLOOK... MVFR/IFR stratus and fog are expected to occur in rounds through at least the end of the week, and increasingly likely to persist through the end of the workweek. Low pressure lifting northward from the Gulf of Mexico toward the end of the week may bring more widespread rainfall and sub- VFR conditions to the region. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Flood Watch until 8 AM EDT this morning for VAZ016-017-032>034- 043>046-058-059. NC...Flood Watch until 8 AM EDT this morning for NCZ003>006-020. WV...None. && $$ SYNOPSIS...BMG NEAR TERM...BMG SHORT TERM...VFJ LONG TERM...JCB AVIATION...BMG