Area Forecast Discussion
Issued by NWS Charleston, WV
Issued by NWS Charleston, WV
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061 FXUS61 KRLX 171808 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 208 PM EDT Thu Sep 17 2026 .WHAT HAS CHANGED... The SPS for hot and humid conditions across the central and southern lowlands has been extended through this evening due to heat indices in the middle-upper 90s. The forecast for the rest of today and into early next week remains on track, with only minor adjustments made. A slight adjustment to the aviation discussion has been made compared to its previous issuance at 131 PM EDT. && .KEY MESSAGES... 1) Chances for heavy showers and thunderstorms remain on the docket for this afternoon and tonight, along with hot temperatures across the lowlands. 2) Rain and storm chances linger across the southern and mountainous areas Friday afternoon, with a lull in rain heading into Saturday before more chances arrive Saturday night and beyond. && .DISCUSSION... KEY MESSAGE 1... In the mid/upper-levels, the center of the subtropical ridge, which was objectively analyzed at 600 dam per the 12Z UA charts, was located over the Lower MS River Valley and continues to retrograde westward. Farther north, a well-defined shortwave trough was digging southeastward towards the James Bay, with the base of the intense jetlets translating over the Great Lakes region. Several series of smaller-scale perturbations were progressing eastward over the Rust Belt and have generated a few bands of general thunderstorms across the northern counties over the last few hours. GOES-East visible trends have recently shown additional bands of congested cu forming to the north of the I-64 corridor between CRW-HTS due the subtle influence of an ejecting shortwave perturbation overhead. There also appears to be a trapped mountain wave on water-vapor imagery that is aiding in the formation of the diurnally-driven cu. The 12Z RAOB from WFO ILN sampled a stout EML, characterized by SB/MUCAPE values exceeding 3,000 J/kg and an equilibrium level up to 125 mb within the belt of broadly cyclonic flow. However, farther southeast at RNK, large-scale subsidence remained intact atop the lower tranche of the EML advecting over the Appalachian Mountains, which should keep the cu field suppressed until peak heating is reached. The subtropical ridge will continue retrograding over the next 24 hours, which will keep the CWA positioned along the edge of the thickness gradient and south of the more-intense flow aloft through Friday. At the surface, the quasi-stationary front remained along and north of the I-70 corridor, but has since become convectively-reinforced, and will begin sagging southward into southeastern OH and northern WV by this evening. Ahead of the front, the airmass is essentially a clone of yesterday less some convective cloud debris, with dewpoints in the lower-middle 70s and hot surface temperatures that have breached 90 degrees, particularly in the OH River Valley. This will result in heat indices in the middle 90s to near 100 degrees for some locales this afternoon, and the SPS highlighting the heat and high humidity has been reissued through 23Z, or 7 PM EDT, this evening for portions of the lowlands. Additional storm development is expected across the lowlands through this evening due to the uncapped airmass, with the mean convective movement governed by propagation along any boundaries. Heavy rainfall will be the primary hazard, leading to localized instances of flash flooding. Following sunset, there will be a temporary lull in showers and storms until the cold front arrives during the overnight hours. As the cold front arrives, another shortwave impulse will propagate over the CWA, with indications pointing towards the potential for semi-organized bands of training storms to develop along the slow, southward-moving cold front. Corfidi vectors favor frontal-parallel back-building of individual cells while the total propagation vector orients southward along the edge of the thickness gradient. The tall, skinny CAPE profiles; anomalously high PWAT content, meager length of the shear vectors, and moist-adiabatic lapse rates will galvanize the heavy rain potential with storms tonight into the predawn hours Friday. However, there exists uncertainty with respect to the spatiotemporal extent of storms during the early morning hours Friday. As a result, confidence is still not high enough to warrant the issuance of a Flood Watch, although it will continue to be evaluated in forthcoming prognostications. The severe weather threat is otherwise low, but a strong wind gust or two cannot be ruled out with collapsing cores overnight. KEY MESSAGE 2... Storm chances will wane from north-to-south after sunrise Friday, with an expectation for river valley fog to return following storms late tonight and an overcast sky lasting into the afternoon hours across most of the CWA. Northwesterly flow will advect over the CWA by mid-day Friday as the shortwave trough currently digging into the James Bay ejects eastward towards the Canadian Maritimes. Elevated, post-frontal showers may develop across portions of the lowlands and mountains during the afternoon hours Friday, with better chances for lightning across the Coal Fields, which will be in closer proximity to the departing cold front. The flash flooding potential is very low Friday nor is severe weather expected with any renegade cells that develop Friday afternoon. Highs are expected to be a few degrees cooler area-wide Friday, albeit still very warm, with heat indices peaking in the lower 90s for the southwestern zones. The cold front is forecast to clear to the south of the CWA late Friday night and become quasi-stationary once again as the subtropical ridge flattens via a neutrally-tilted shortwave trough emerging over the central Rocky Mountains. Progressive flow aloft will persist to the north of the CWA Saturday, and mostly dry conditions are forecast, with the exception of the mountainous terrain where diurnally-driven, pulse-like showers and storms may develop in the afternoon hours. The quasi-stationary front to the south of the CWA will also undergo warm-frontogenesis and lift northeastward across the CWA throughout the day Saturday, with benign surface winds transitioning to the southeast beneath the prevailing westerlies aloft. By Saturday night, another series of shortwave perturbations will eject over the CWA following the passage of the warm front, with renewed chances for heavy showers and storms arriving overnight Saturday into Sunday. Active weather continues to be forecast through early next week as the subtropical ridge finally breaks down due to an evolving split-flow pattern. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... VFR will prevail for the remainder of the afternoon and evening at all terminals, minus off-and-on bouts of -SHRA/-TSRA. The latest satellite trends have indicated that the bulk of the cu field has remained suppressed, but pop-up -SHRA/-TSRA will certainly be a possibility during the latter half of the afternoon. Therefore, a VCTS mention has been carried for all TAF sites this afternoon, with afternoon TSTM potential waning by dusk. That said, the potential for heavy TSTMs will return overnight, potentially affecting all terminals. Expect reductions to CIGs/VSBYs with any overnight TSTMs. Beyond the overnight TSTM risk, river valley fog is forecast to also develop once again and affect all terminals except KBKW. LIFR/BLO MINS may occur at some of the sites, with CIGs/VSBYs after sunrise and on the backside of any TSTM complexes departing to the south of the terminals. At least MVFR CIGs will linger Friday morning and through the end of the TAF period at all terminals. FORECAST CONFIDENCE: High through this evening, then low-medium tonight. ALTERNATE SCENARIOS: The coverage and timing of showers and thunderstorms tonight may vary from the forecast. The extent of fog early Friday morning may also vary from the forecast. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H L PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 18Z FRIDAY... Low CIGs will gradually improve to VFR beyond 18Z Friday, with the potential for lingering -SHRA/-TSRA to affect some of the terminals Friday afternoon. Morning valley fog will continue through the weekend. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ DISCUSSION...Sincavage AVIATION...Sincavage