Area Forecast Discussion
Issued by NWS Charleston, WV
Issued by NWS Charleston, WV
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024 FXUS61 KRLX 210538 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 138 AM EDT Sat Sep 21 2024 .SYNOPSIS... Mostly dry and warm under high pressure. A weak system passes through over the weekend, and may trigger a few showers over and near the mountains on Saturday. && .NEAR TERM /THROUGH TODAY/... As of 900 PM Friday... No major changes were made to the overnight forecast as things appear to be largely on track. Still expect some river valley fog to develop, but outside of the high valleys, there`s some uncertainty on the extent of the fog, so the day shift`s fog forecast was left as-is. As of 120 PM Friday... Mostly dry conditions expected tonight as a surface high pressure slides east of the Appalachians. Patchy dense fog will be possible once again, along the most protected river valleys. Any fog will quickly dissipate by 9 AM Saturday morning. A weak shortwave, evident at H700, will push a cold front Saturday morning with isolated light showers, as shown by a few of the deterministic models. Therefore, added low PoPs for the onset of precipitation Saturday morning across SE OH, spreading east across WV through the afternoon. Then, aided by afternoon heating, showers and thunderstorms should develop across the area into the evening hours. Moderate instability with CAPE reaching 1,800 J/kg and PWATs +2 standard deviation from the mean suggest storms may produce localized heavy downpours. In addition, dry air in the mid levels may allow for strong downburst capable to produce damaging winds. SPC has most of the area under general thunder, and a marginal risk for severe thunderstorms across the northeast mountains for Saturday. Tonight`s lows will range from the low to mid 60s lowlands, into the mid 50s northeast mountains. Highs on Saturday will reach the lower 90s across the lowlands, ranging into the lower 70s northeast mountains. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... As of 952 AM Friday... An upper-level ridge will briefly move over the area Sunday with the return of dry, hot, and sunny weather areawide. Increased fire danger will return Sunday afternoon, especially in the lowlands, with afternoon minimum RH values expected to range from 30-40% across the central and northern WV lowlands and portions of southeast OH. High temperatures will reach the lower 90s across much of the lowlands during the afternoon. Rain chances will slowly increase from west to east Sunday night as 500-mb heights lower and the next low pressure system approaches. The best chance of showers Sunday night into Monday morning will be across southeast Ohio. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 952 AM Friday... A wave of low pressure will track into the Great Lakes Monday with a trailing cold front moving into the Ohio Valley. This will bring more moisture into the area with afternoon minimum RH only expected to drop to 50-60% across the WV lowlands and southeast OH. This should mitigate the fire threat. In addition, shower chances will return, with the greatest chances across northern WV and southeast OH. The rest of the week looks unsettled with chances of rain just about each day as waves of mid-level vorticity flow along the approaching trough. Given our drought situation, this is good news. Another cutoff upper-level low is expected to develop by the middle of next week, over the midwest or the Great Lakes, with not much movement expected through the end of next week. This should bring daily chances of showers for our region. Confidence is still low at this time, but there is potential for some beneficial rainfall. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... As of 140 AM Saturday... Pockets of FEW to SCT mid-level clouds will mitigate river valley fog from seeping away from the mountains overnight. Therefore, continue to portray a similar tale to the previous forecast with only EKN having the potential for IFR vsbys through early Saturday morning. A weak cold front passes through the area on Saturday, bringing a broken deck of clouds and the chance for mountain showers/storms in the afternoon. Airfields should remain VFR during this timeframe, but VCSH/VCTS was included for sites close to forecast POPs for this afternoon and evening. In the wake of the front, better potential for fog to ooze down into the lowlands will transpire. This will be especially true for areas that receive rain. Calm winds overnight will shift out of the west/northwest for the second half of the day Saturday in response to FROPA. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing and extent of fog may vary from 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. DATE SAT 09/21/24 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EDT 1HRLY 23 00 01 02 03 04 05 06 07 08 09 10 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 L L M M M M M M H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 06Z SUNDAY... IFR conditions possible Sunday morning with river valley fog in some of the higher valleys around the area. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...FK/ARJ/JMC NEAR TERM...FK/ARJ SHORT TERM...JMC LONG TERM...JMC AVIATION...MEK