Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 200719 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 319 AM EDT Thu Jul 20 2017 .SYNOPSIS... Convective activity on the increase into the weekend with heat persisting. Frontal system passes early next week. && .NEAR TERM /THROUGH TONIGHT/... As of 730 PM Wednesday... No changes necessary. As of 215 PM Wednesday... Isolated showers have developed across the forecast area this afternoon in the moist unstable atmosphere. But overall, threat for showers remains quite low, and any should dissipate by sunset with the loss of heating. Tonight will be similar to previous nights, with a mostly clear sky, and patchy river valley fog developing towards morning. Thursday, strengthening upper ridge and warmer low level temperatures should result in temperatures a few degrees warmer. A shortwave will move east across the Great Lakes late in the day on Thursday/Thursday night, with increasing chances of showers and thunderstorms, particularly across southeast Ohio towards the end of the period. Some of the storms could be on the stronger side, with increasing shear 30-40kts, but overall, better dynamics lie to the north, and timing of storms is late, which should help to mitigate the threat in the near term somewhat. SPC has the area in a marginal risk for storms. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 305 AM Thursday... The short term transition brings an increase in the mid level dewpoints and a marked increase in the surface based instability Friday and especially into Saturday. As advertised, northwest flow aloft will drop into the CWA, as well as a weaker surface boundary from a surface low lingering in the plains states. The low level frontogenetic forcing with the boundary will be less than impressive, but even weak forcing with the temperatures nearing their convective temperatures and disturbances aloft in the 500mb gradient should be able to initiate convection. In the meantime, lowland dewpoints and temperatures will couple to push and exceed the 100 heat index criteria Friday and Saturday. Will mention again in the HWO. Some concern about cloud cover and showers possibly keeping those values at bay a bit, but need to push that threat. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 305 AM Thursday... As the upper ridge retreats to the west, plains area surface low will finally track eastward as an upper level open wave drops into the Great Lakes. Expect some organization to the convection as the frontal system approaches and the magnitude of the low level frontogenesis increases. This should lead to some early next week relief to the temperatures and dewpoints for a short period of time. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... 06Z Thursday thru 06Z Friday... As of 200 AM Thursday... Upper ridging continues to weaken. A frontal system over the upper midwest early this morning will drop southeastward today and tonight, but staying just north of our area by 12Z Friday. Today... More widespread MVFR haze/fog for mainly the river valley areas early this morning as compared to yesterday morning, with patchy IFR fog mainly affecting PKB and EKN 09Z- 12Z. Thereafter, generally SCT 5000-7000 feet AGL except becoming BKN far northern portions of area by around 00Z. Models have a mid level dry slot crossing today ahead of the front. Associated convection and deeper moisture with the front is expected to remain mostly north of our area until around 00Z. Thus, will leave convection out of most of the area and the major TAF sites today. Tonight... Even though frontal system sags ever so slowly southward and will remain just north of our area by 12Z Friday, west to northwest flow aloft is expected to carry the deeper moisture and convection southward across the north and into central sections of WV by 12Z Friday. However, despite deep moisture, the diurnal timing will tend to diminish the convection, and will keep the convection as scattered. So, given this uncertainty with the convection, will keep mention out of the northern TAFS of PKB, CKB and EKN for now. Dry south. Generally VFR ceilings 4000-7000 feet across the north, except lower in scattered convection, while SCT mid level clouds prevail in the south. Near calm winds by night, and west winds 5 to 10 KTS by day. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: IFR Fog development early this morning may vary from forecast. Timing and southward extent of convection may also vary. 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 THU 07/20/17 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY H H M M M M M H H H H M HTS CONSISTENCY H H M M M M M H H H H M BKW CONSISTENCY H H H M M M M H H H H M EKN CONSISTENCY H H M M L L M H H H H M PKB CONSISTENCY M L L L L L M H H H H M CKB CONSISTENCY M M M L L L H H H H H M AFTER 06Z FRIDAY... Patchy IFR river valley fog is possible Friday morning, and Friday and Saturday in showers and thunderstorms. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JMV/26 NEAR TERM...JMV SHORT TERM...26 LONG TERM...26 AVIATION...JMV is the U.S. government's official web portal to all federal, state and local government web resources and services.