Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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547 FXUS61 KRNK 251037 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 637 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/... As of 200 AM EDT Wednesday... Key Messages: - Outer rain bands from Tropical Storm Helene will enter the area Thursday night. - 1 to 5 inches of rain is possible with the highest amount in the NW NC mountains. - Breezy and Gusty winds are likely Thursday night into Friday. An upper level low will wobble in the vicinity of Memphis TN while an upper level ridge sits off the southeast coast. These two systems will help guide Tropical Storm Helene as it enters the Gulf of Mexico. Tropical Storm Helene is expected to become a hurricane as it moves over the warm waters of the eastern Gulf of Mexico Thursday. Helene is expected to move inland around the Big Bend area of Florida Thursday evening, then turns northward towards the southern tip of the Appalachian mountains (NE GA) Thursday night. Rain showers are forecast to enter the North Carolina High Country between midnight and sunrise Friday morning. The rain shield of moderate rainfall could possibly extend northward into SE WV and the Virginia Highlands during the morning commute Friday. Helene will then make a turn to the northwest as it gets caught up in the upper low. Tropical rain bands will move across RNK`s forecast area through late Friday afternoon. Helene is expected to get absorbed into the upper low Friday night. Rainfall amounts will generally range between 1 to 2 inches across the area. Rainfall amounts of 2 to 5 inches are possible for counties bordering the Blue Ridge from Roanoke County VA southward into Watauga County NC. Winds from Helene will range between 15 to 25 MPH with gusts as high as 40 MPH late Thursday night into Friday morning. The higher end of the range will primarily be across the NW North Carolina High County, the Grayson Highlands and the Mountains Empire of SW Virginia between midnight and noon Friday. Even though winds speeds will not reach advisory criteria, shallow rooted trees could topple as ground will be saturated. High temperatures Thursday and Friday will range from the mid 60s to mid 70s across the mountains and in the 70s over the foothills and piedmont. Humidities will remain high with a tropical airmass over the region. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 230 AM EDT Wednesday... Key Messages: 1) Tropical airmass remains through Saturday. 2) Cooler weather arrives Sunday behind a cold front. 3) Low rain chances are possible each day through the middle of next week. 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 /12Z WEDNESDAY THROUGH SUNDAY/... As of 635 AM EDT Wednesday... Poor flying conditions with widespread IFR/LIFR across the area. A combination of low cigs/vsby, along with areas of heavy downpours 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 with some modest clearing possible. 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 from 2 PM EDT this afternoon through Thursday evening for VAZ007-009-015. Flood Watch until 8 AM EDT this morning for VAZ016-017-032>034- 043>046-058-059. NC...Flood Watch from 2 PM EDT this afternoon through Thursday evening for NCZ001-002-018-019. Flood Watch until 8 AM EDT this morning for NCZ003>006-020. WV...None. && $$ SYNOPSIS...BMG NEAR TERM...BMG SHORT TERM...RCS LONG TERM...JCB AVIATION...BMG