Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 202335 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 735 PM EDT WED JUL 20 2016 .SYNOPSIS... High pressure in control with dry and stable air. Getter hotter. Weak disturbances could drop southeast around ridge Friday night and Saturday. && .NEAR TERM /THROUGH THURSDAY/... Update... A very tight dewpoint gradient exists along the northern border of the CWA with a reading of 57 at CKB and 48 at MGW. MET guidance too cool with the overnight lows in the mountain valleys...and hug the warmer values of the MAV. No wholesale changes to the forecast this evening with upper level ridging building in over the Ohio Valley and west. Previous Discussion... as of 17z...daytime heating forming cu over the central and southern counties. Further north...air drier...so cu will struggle to form. Temperatures continue to rise faster than mos guidance and more along our trace with a hotter maximum temperature around 21z. Winds remain light with strong surface heating. With the lower dew points...have minimum temperatures lower at dawn Thursday than dawn Wednesday. Lowered minimum from our previous forecast for northern counties and central mountains with the lowest late afternoon dew points. Still have river valley fog forming first in southern coal fields of WV and cooler mountain valleys. Overall...a bit later in forming and less coverage than 06z to 12z Wednesday. Will try to stay on high side of maximum temperature guidance for Thursday as top soil gets drier. Winds remain light. Dew points remain aob normal levels during the afternoon. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... The heat builds into the weekend. It looks like a string of 90s will carry at least thru Sunday. Dewpoints will initially start out in the low to mid 60s...but creep up past 70 by Friday. As a result...heat indices will climb to near 100 by Friday for portions of the Lowlands. We will have to watch for a disturbance coming down in the NW flow aloft Friday evening for shot at shra/tsra...otherwise dry thru the period. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... The heat will continue thru Monday with this weekend serving as the apex as the upper level ridge axis plagues the central parts of the country...keeping the extreme heat at bay thankfully. Still...highs in the low to mid 90s with dewpoints in the lower 70s will create heat index values likely eclipsing the 100 degree mark Saturday and Sunday. Will keep the mention of potential heat advisories in the current HWO. A caveat in realizing such thresholds will depend on areal coverage of any convection. A moisture axis from the upper level wave that comes thru Friday night may linger on Saturday as the ridge axis makes subtle changes. This may provide the lift for aftn convection once any mid level cap is broken. Our far NE zones may stay capped to keep the day dry. Another upper level wave will help to flatten the ridge some on Sunday and especially early next week with increased threat for shra/tsra long about Monday. The associated weak surface front will meander thru the area into midweek with a daily shra/tsra threat. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... Keeping the trend of the late IFR fog in the coal field river valleys...and in the northeast mountain valleys. Will stay with the same timing in a persistence type forecast from the previous morning. Model guidance looks to be too aggressive...including LAMP guidance...and have a more optimistic forecast in place overall. VFR after 13Z Thursday. CONFIDENCE AND ALTERNATE SCENARIOS... FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z FRIDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: With cooler temperatures...fog could be briefly thicker than forecast at CRW for an hour or 2 near dawn. 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 22 23 00 01 02 03 04 05 06 07 08 09 EDT 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 CRW CONSISTENCY H H H H H H H H H H H M 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 M L 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 00Z FRIDAY... No widespread IFR expected. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...KTB/30 NEAR TERM...KTB SHORT TERM...30 LONG TERM...30 AVIATION...26

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