Area Forecast Discussion
Issued by NWS Blacksburg, VA
Issued by NWS Blacksburg, VA
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587 FXUS61 KRNK 241919 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 319 PM EDT Tue Sep 24 2024 .SYNOPSIS... A slow-moving cold front will meander along the Ohio River Valley over the next several days, triggering rounds of showers and thunderstorm activity that will persist through much of the workweek. PTC 9 lifting northward from the Gulf of Mexico toward the end of the work week may bring more widespread rainfall to the region. && .NEAR TERM /THROUGH TOMORROW/... As of 200 PM EDT Tuesday Key message: 1) An upper level trough and associated cold front will approaching the region today will lead to continued shower and thunderstorm activity overnight tonight and into the early morning hours on Wednesday before becoming more isolated in nature through Wednesday afternoon. An upper level trough that has been digging southward today is expected to separate from the main northern flow by Wednesday, and become quasi-stationary across northeastern Arkansas and western Tennessee. As this happens, upper level ridging is expected to build across the southeastern coastal plain, and off the southeast coastline. While This happens throughout the day on Wednesday, a strengthening jet streak in a southwest to northeast orientation is expected to develop from the lower Mississippi valley towards West Virginia. This 250mb jet orientation coupled with upper level divergent flow through the 500mb level will lead to scattered shower and thunderstorm activity across the region for much of the morning on Wednesday, with a possible break in the mid morning before additional storms develop through the afternoon hours across the I-77 corridor into West Virginia. While much of the eastern half of the area will dry out through the afternoon and evening, cloud cover is expected to be plentiful across the region as mid and upper level clouds from the south and southwest stream north. This will keep temperatures in the low to mid 70s across higher terrain, and in the upper 70s to near 80 across the Piedmont. Lows Wednesday morning will generally fall into the low to mid 60s areawide. && Short Term .../WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/ ... As of 135 PM EDT Tuesday... 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 /18Z TUESDAY THROUGH SUNDAY/... As of 130 PM EDT Monday... Clearing across southwest Virginia and southeastern West Virginia has lead to scattered shower and thunderstorm development across these regions over the last hour or so. This will lead to VCTS conditions at KBLF, KLWB, KBCB, and KROA for the next several hours and into the evening. As these showers and thunderstorms pass near or over terminals, expect brief MVFR to LIFR conditions. KDAN and KLYH look to remain under dense cloud cover through the entire TAF period; however, TSRA conditions look to impact both terminals through the overnight hours. MVFR to LIFR conditions look to return to all terminals beyond 0900 UTC Wednesday, and linger through 12-15 UTC on Wednesday before conditions start to improve to MVFR to VFR levels as visibilities increase, and CIGs lift. EXTENDED AVIATION OUTLOOK... MVFR/IFR stratus and fog are expected to occur in rounds through at least the middle of the week, and increasingly likely to persist through the end of the workweek. Rounds of showers and thunderstorms will also continue to pass across the lower Mid- Atlantic. 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...None. NC...None. WV...None. && $$ SYNOPSIS...EB/BMG NEAR TERM...EB SHORT TERM...VFJ LONG TERM...JCB AVIATION...EB/BMG