Area Forecast Discussion
Issued by NWS Charleston, WV

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262 FXUS61 KRLX 221430 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 1030 AM EDT Wed May 22 2019 .SYNOPSIS... Much warmer today into the weekend with chances for showers and thunderstorms somewhere in the area each day. && .NEAR TERM /THROUGH TONIGHT/... As of 1027 AM Wednesday... Minor adjustments made to hourly temps for this morning, owing to rapid warming that is occurring. Otherwise, no changes needed to inherited forecast at this time. May need to expand POPs across the N/NW CWA a little farther southward late this afternoon, but will await for analysis of incoming 12z guidance suites before making and changes to precip chances this afternoon. As of 635 AM Wednesday... Forecast on track with upper level ridge overhead, but on its way out. As of 315 AM Wednesday... Upper level ridge exits this morning, allowing a weak mid level short wave trough to traverse the mid and upper Ohio Valley this afternoon and evening. Dew point pooling in this area along and southwest of a warm front lifting toward the PA/OH state line will contribute to CAPE values up to 1.5 KJ/kg during peak heating. Bulk shear values into the 30s suggest a marginal risk for severe thunderstorms as depicted by SPC, but 0-3km SRH values possibly as high as 300 m2/s2 also suggest rotating updrafts. The weakness of the wave and lack of deep layer moisture suggested only isolated to scattered coverage, but PW values are progged as high as 1.5 inches, so locally heavy downpours are possible. The remainder of the area will have a summer likely day, noticeably warmer than Tuesday, with highs topping out some 15 degrees higher. Opted to stick with the previous forecast for highs, in line with MOS but slightly higher than central guidance, Any thunderstorms will weaken with loss of heating tonight as they move east across the northern tier and into lower dew points. Otherwise southerly flow will make for a warm night with lows close to central guidance and MET and higher than the MAV even in the valleys. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... As of 348 AM Wednesday... The potential for severe weather will be the main focus on Thursday. Upper level ridge in place across the southeast CONUS will get briefly shunted southward due to the presence of a shortwave trough that will be moving across Ontario through the day. As the ridge axis pushes southward, a belt of westerly mid-level flow of 55-60 kts will stream across the region, particularly northern areas of the CWA where the winds aloft will be stronger. Shortwave energy embedded in the westerly aloft will provide forcing for ascent; while at the surface, a cold front will move across the region Thursday afternoon into the evening as the shortwave trough and associated surface low move eastward into Quebec. With our region in the warm sector for much of the day, dewpoints will rise to the upper 60s with some areas reaching 70F in the afternoon. This will combine with daytime heating to support MLCAPE values in the 2,000- 3,000 J/kg range. In addition, 0-6 km Bulk shear values will be around 40-50 kts, with the higher values more common in the northern portions of the CWA. Due to the stronger dynamics, greater instability, and better forcing in the northern areas, SPC has issued a slight risk for severe storms generally along and north of a line from Ironton to Sissonville to Mill Creek. A marginal risk then covers the remainder of the CWA, with the exception of MCDowell county and our SW VA counties. In regards to the greatest hazards with Thursday`s storms, latest forecast soundings indicate that DCAPE values could be in the 900-1000 J/Kg range, suggesting that strong straight-line winds would be the primary threat with this activity. Hail will also be a concern given the instability expected, and suppose a tornado threat can`t be completely ruled out with 0-3 km SRH values in the 200-250 m2/s2 range; suggesting that some rotating updrafts will be possible. The cold front will mostly push east of the region by Friday morning, however, models suggest that the boundary may stall across southern areas providing just enough of a focus for isolated showers and storms Friday. Given the dry atmosphere in place as the ridge in the southeast builds northward into the region on Friday, any chances for convection will be small and currently just have low slight POPs across the southern coal fields and into SW VA where just enough lift may be present as the frontal boundary lingers in the region. Regardless, a mainly dry and warm day is expected with highs in the mid to upper 80s across most of the region. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 348 AM Wednesday... Warm and humid conditions will continue into the weekend as the persistent upper ridge remains in place in the southeastern CONUS. Saturday will be toasty with widespread highs in the upper 80s and approaching 90 in many locations. The threat for precipitation will once again increase as a low pressure system moves across northern Ontario and a trailing cold front moves eastward across the Ohio Valley. Aloft, embedded disturbances will move along the northern periphery of the ridge and interact with the frontal boundary to support a mention of showers and storms. The highest POPs Saturday afternoon will be near the mountains, aided by the orographic influence, but there will at least be a chance of a shower or storm elsewhere given the warm and humid airmass in place. Coverage of showers and storms will increase by Sunday as the east to west oriented frontal boundary lingers in the Ohio Valley and disturbances embedded in the zonal flow aloft move through. Currently have chance POPs across the majority of the region for better confidence in greater storm coverage on Sunday, and even low likely POPs in northern areas that will remain closer to the stalled boundary. Temperatures remain above seasonal with highs in the mid 80s across the area. It will remain unsettled into the new week as the active westerly flow aloft continues with a continuation of showers and storms. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... As of 635 AM Wednesday... VFR conditions can be expected through the period, with the possible exception of showers or thunderstorms late this afternoon into tonight over the middle Ohio Valley. Light east surface flow across the lowlands early this morning and southeast flow across the mountains, a bit gusty on the ridges, will become south 5 to 10 kts throughout the area today, and continue through tonight. Flow aloft will be moderate southwest. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: A thunderstorm may impact PKB or CKB late this afternoon into tonight. MVFR stratocu may approach BKW from the southeast tonight. 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 12 13 14 15 16 17 18 19 20 21 22 23 EDT 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 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 M M EKN CONSISTENCY H H H H H H H H H H H 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 12Z THURSDAY... Widespread IFR conditions are not expected at this time. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/MZ/RG NEAR TERM...RH/TRM SHORT TERM...RG LONG TERM...RG AVIATION...TRM

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