441 FXUS61 KRLX 041417 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1017 AM EDT Tue Jul 4 2017 .SYNOPSIS... A weak frontal boundary will sag south and stall out across the area through mid week before moving back north. Cold fronts Thursday night and Friday night. Cooler and less humid weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 1015 AM Tuesday... Sent a quick update to increase PoPs across the southern third of the area through at least 18Z. The rest of forecast remains on track. As of 515 AM Tuesday... Weather becomes more active today. Frontal boundary at 830Z stalled out near Ohio River. Still progged to sag a little farther south today, and will be a focal point for convection later this afternoon. Main player today however will be a wave of low pressure that will move east out of the Mississippi Valley region towards the CWA, with showers and thunderstorms, particularly across southern and eastern zones. Storms will be slow movers, and with the high moisture content of the air, will produce heavy rainfall. Flooding threat should remain low however. With the expected cloud cover/convection today, temperatures should be slightly cooler across much of the area than recent days. Southeast Ohio may however be a bit warmer than other parts of the CWA due to less convection/cloud cover. Bulk of activity decreases tonight with loss of heating, and as low pressure wave moves east of the area, with a cloudy, muggy night on tap. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... As of 515 AM Tuesday... Active early July pattern this period, with upper level split flow that unifies and amplifies, with a trough in the east, and a large upper level high over the intermountain west. A short wave trough in the southern stream, over the central plains early this morning, reaches the mid Mississippi valley Wednesday morning, and the forecast area Thursday night. It, and weak ripples ahead of, along with an aging front in the area, in the very warm and humid air, spell rounds of showers and thunderstorms Wednesday into Thursday night, timing and location to be further modulated from outflow boundaries. The forecast area is hydrologically dry, but PW values are progged to climb over 2 inches with these waves. With light deep layer flow Wednesday, thunderstorms will be slow movers, and could produce locally excessive rainfall. The flow increases Thursday but, by then, some areas may have become primed. As the pattern amplifies Friday and Friday night, a cold front drops southeastward through the area, with another round of showers and thunderstorms. There may not be quite as much moisture available by Friday, but the flow will be stronger, so the opportunity for severe weather will be better if the storms arrive early enough, which is currently forecast to be the case. Temperatures close to a guidance blend. The MAV was low and the MET high on highs Wednesday, on account of a wetter solution depicted by the GFS, compared with the NAM. Slowed cooling and drying a bit from central guidance overnight Friday night, but cooler and less humid air will be on the way in the wake of the front. && .LONG TERM /SATURDAY THROUGH MONDAY/... As of 515 AM Tuesday... This period is characterized by continued troughing in the east, while an upper level high remains parked over the intermountain west. A short wave trough crosses Saturday, followed by cool Canadian high pressure Sunday. A rather cool Sunday morning is on tap, if the high builds in quickly enough. Canadian high pressure, with cooler and much less humid air, will filter in on Saturday. This feature should remain in control of our weather into Monday. Low level southeast flow around the back side of the high exiting to the north, may bring showers back into the WV mountains Sunday or Monday. A short wave trough is progged to back the upper level flow, and generate cyclogenesis over the area on Tuesday, although the latest ECMWF backs away from this idea. Central guidance temperatures accepted, which show a cool weekend, and then values moderating back toward normal early next week. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... As of 620 AM Tuesday... Patchy mvfr and ifr valley fog through 12-13Z. Otherwise, Showers and thunderstorms will be on the increase, particularly after 16Z, particularly across southern WV, the mountains, and southwest Virginia. Expect brief MVFR conditions in showers/storms. Bulk of convection will begin to dissipate after 00-02Z, however, -shra, along with widespread MVFR cigs expected to develop for remainder of TAF period. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of showers and storms on Tuesday may vary from forecast. Development of widespread MVFR cigs tonight may not occur. 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 M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H H M M H M EKN CONSISTENCY H H H H H H H H H H H M 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 12Z WEDNESDAY... IFR possible in showers and thunderstorms Thursday into Thursday night, and late Friday. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...ARJ/SL SHORT TERM...TRM LONG TERM...TRM AVIATION...SL