Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 232346 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 746 PM EDT Sun Apr 23 2017 .SYNOPSIS... Upper level low passes to our south tonight and then swings east to the Carolina coastal states Monday, keeping rain mainly in the south and east through Monday. Warmer midweek before a cold front crosses Thursday night. && .NEAR TERM /THROUGH MONDAY/... As of 740 PM Sunday... Updated POPs based on current trends and hi-res guidance. Did not make any real significant changes, but mainly just tightened up gradients a bit. Opted to extend flash flood watch until 18Z Monday with the next wave of precip drifting up from the south and lingering into Monday. Really, we are in more of a flood than flash flood scenario now with lots of minor issues already ongoing. However, think canceling the flash flood watch just to issue a flood watch is counterproductive and likely confusing. As of 200 PM Sunday... While there are typical model differences in the exact handling of the broad upper low currently over the western Tennessee valley this period, all are indicating SIMILAR main effects for our area. The associated rain shield just over our southern most zones early this afternoon will struggle to shift northward this afternoon and evening. As the upper low slides south southeast into the southeastern states tonight, the rain shield will tend to shift slowly eastward and spread up the WV mountains. This process will continue Monday as the upper low then reaches the Southeast coast. By Monday afternoon, most of the rain will have shifted into the mountains. Thus, will keep the northwest half basically dry and the southeast quite wet, with a tight POP gradient in between. In addition, the good influx of moisture and steady but persistent rain over the southern mountains will validate continuing the Flood Watch as is, with flood warnings already in effect for SW VA. The watch may very well have to be extended and expanded up the mountains later tonight and Monday, but there is enough uncertainty in the exact track of the upper low and the axis of heavy rain for further evaluation. Otherwise, look for coolest temps tonight and warmest temps Monday over northwest portions of the area given less thick clouds and lack of rain. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 245 PM Sunday... Influences from the cut off upper low over the Southeast will continue through Tuesday as an inverted trough remains over the area. Precipitation chances will largely be confined to the eastern half of the CWA, while the low and mid level moisture starts to dissolve CWA wide after Tuesday. Improvements expected all around with temperatures on the increase, and the far southern zones drying out after a few days of persistent rain. Expecting a significant increase in 500mb heights heading into Wednesday, and an 850mb temperature jump of 5-8C. In the meantime, the upper trough merger over the central states will be occurring. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 245 PM Sunday... Getting quick cyclogenesis occurring with the upper trough merger over the Midwest, and a strong frontal system deepening into the western Great Lakes. The models continue to take it towards northern Ontario, so the cold front is still expected to shear out considerably as it passes through the Ohio Valley. Still needing POPs into Thursday, with thunder, but overall it should be a weakening cold front as it affects our area. Strong upper level ridge builds over the southeastern states while a southern plains upper low deepens, developing another surface low. Warm frontal influences keep low end chances for precipitation into the weekend, but the temperature trend continues to go upwards, with summer like readings prevailing. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 740 PM Sunday... Currently VFR across the forecast area, but expect lowering ceilings from south to north tonight into Monday. Expect MVFR at most locations, with IFR possible at BKW. Most guidance actually has backed off the IFR there, but with lots of IFR just to the south, opted to include it despite lower confidence. Will also have rain spreading across the south and east tonight which could result in some MVFR to IFR visibilities. Rain will linger across the east Monday, with clouds gradually lifting and breaking up from the west late in the day. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY... FORECAST CONFIDENCE: Low to Medium. ALTERNATE SCENARIOS: Timing of rain and category changes may vary. BKW may not get into IFR. 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 MON 04/24/17 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H M M M M M M L HTS CONSISTENCY H H H H M M M M M M M L BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY H H H H H H H M M M 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 00Z TUESDAY... IFR may linger across the mountains into Monday night. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flash Flood Watch through Monday afternoon for WVZ033-034. OH...None. KY...None. VA...Flash Flood Watch through Monday afternoon for VAZ003-004. && $$ SYNOPSIS...JMV/26 NEAR TERM...JMV/MZ SHORT TERM...26 LONG TERM...26 AVIATION...MZ

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