Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 271942 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 342 PM EDT Thu Jul 27 2017 .SYNOPSIS... Low pressure system brings rounds of showers and thunderstorms, with heavy rain through Friday. High pressure with cooler and less humid air follows for the weekend into next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 215 PM Thursday... The HRRR and the RAP have been consistently depicted a relative lull in the convection for about a 4 hour window or so, with the timing depending on location, before the next wave of convection moves through. After a morning of priming with scattered storms, a flash flood warning is now in effect until the front exits the region tomorrow evening. PWAT values are in the 1.5 to 2.0 inch range again, hence the heavy rain that has already been seen, with many cells giving one half inch in 30 minutes being the norm. Instability is high in the mixed and most unstable layers. Convective debris is dissipating off to the west, so expect the convection to fire again upstream, as mentioned earlier in regards to the flash flood watch. Severe threat is marginal, and most storms have not eclipsed the 35mph wind mark, nor have they produced any hail. High dewpoints keep the overnight lows near 70F for the lowlands. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... As of 315 PM Thursday... Models continue to target our area for heavy rain Friday. Waves of low pressure will be moving up along a slow moving cold front that will cross our area from west to east during the day Friday. With very moist (PW`s above 2 inches) and unstable air in place with the front, there is a Flash Flood watch through the day Friday. The front will finally be kicked east of the area Friday evening as an upper low drops south across the Great Lakes and into our area. Showers will end from west to east west of the Ohio River Saturday night, but showers will continue through the day Saturday over much of West Virginia as the upper low stalls over the Mid Atlantic states. The upper low finally shifts far enough east for all rain to end saturday night. It will be warm and humid ahead of the front, and much cooler behind the front with temperatures going well below normal. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 335 PM Thursday... A cool and dry period is on tap as Canadian high pressure will be in control from Sunday into much of the next work week. There will be a slow increase in high temperatures each day, but it will be dry with temperatures at or below normal. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... As of 120 AM Thursday... The general theme is rounds of showers and thunderstorms through the TAF period. It is important to note, however, that in thunderstorm environments, the atmosphere changes significantly from the model initializations, and in many cases, renders the second half of the forecast inaccurate. Thus, there will likely be significant timing issues with the TSRA/VCTS in the forecast beyond the 6 hour time frame. Also carry lower ceilings in visibilities tonight, particularly as rain subsides. This is primarily a 04Z to 14Z time frame, different at each terminal. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE: Medium to high on the occurrence of convective activity, low on timing. ALTERNATE SCENARIOS: Timing of showers and thunderstorms, and associated flight categories, could vary, with short term amendments likely needed. 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 L HTS CONSISTENCY H H H H M L L M H H H L BKW CONSISTENCY M H H H H H H H M M M L EKN CONSISTENCY H H H H H H H H H M H M PKB CONSISTENCY H H H H H L H H L H H M CKB CONSISTENCY H H H H H H H H H H L M AFTER 18Z FRIDAY... Brief periods of IFR conditions with thunderstorms likely through Friday. Fog possible Friday night. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flash Flood Watch from 8 PM EDT this evening through Friday evening for WVZ005>011-013>020-024>034-039-040-515>526. OH...Flash Flood Watch from 8 PM EDT this evening through Friday evening for OHZ066-067-075-076-083>087. KY...Flash Flood Watch from 8 PM EDT this evening through Friday evening for KYZ101>103-105. VA...Flash Flood Watch from 8 PM EDT this evening through Friday evening for VAZ003-004. && $$ SYNOPSIS...JMV/26 NEAR TERM...26 SHORT TERM...JMV LONG TERM...JMV AVIATION...26

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