116 FXUS61 KRLX 162341 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 741 PM EDT Fri Aug 16 2019 .SYNOPSIS... High pressure with dry weather tonight. Storms possible across north from passing disturbances this weekend. Cold front midweek with high pressure for the latter part of next week. && .NEAR TERM /THROUGH SATURDAY/... As of 735 PM Friday... Quiet weather night across the region with fog development being the main forecast challenge overnight. While the flow will be light and many areas will decouple, there could be enough high level cloud cover moving in ahead of upstream convection across the central Plains to complicate the fog potential. Thinking the best chance will be in the deeper river valleys of the region. Other than making some tweaks to sky cover, the remainder of the forecast remains on track. As of 1240 PM Friday... Overall, no major changes were necessary from the previous near term forecast. Did elect to add a slight chance of a shower or storm across northern mountains this afternoon during peak heating hours, but overall, area should remain dry. Less fog development expected tonight due to another day of drying conditions, and the possibility of cloud cover moving across the area from convective activity to our west. Deeper mountain valleys will be most likely to see much fog development. Showers and storms will be possible across the northern zones on Saturday, as shortwave moves across the area, and surface front develops across the midwest and Great Lakes region. Some storms across far northern zones could be strong tomorrow, with 30-35 kts of shear, but overall, better threat will be farther to the north and east of the CWA. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 215 PM Friday... The short term will be dominated by weak flow aloft with a ridge of high pressure off the East Coast. At the surface weak high pressure will linger into the start of the work week. Models do show a couple of weak 500mb impulses crossing, one on Sunday and another on Monday. With hot and humid conditions at the surface, these impulses may be enough to kick off isolated to scattered showers and storms, especially across the elevated heat source of the mountains. The NAM keeps everything dry, while the GFS and ECMWF each show some light QPF. Kept POPs fairly diurnal in nature, with isolated to scattered coverage maxing out during the late afternoon and early evening, and then tapering off after sunset. Both Sunday and Monday will be warm than normal for mid August, with highs across the lowlands in the low to mid 90s. Higher elevations will see upper 70s and 80s. Muggy overnights can be expected with dewpoints in the mid to upper 60s across most of the area. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 215 PM Friday... Hot and humid conditions continue Tuesday with mostly diurnally driven shower and thunderstorm activity. Models begin to diverge in handling of upper trough and associated cold front approaching Wednesday/Wednesday night with EC based guidance around 6 to 12 hours faster and more aggressive with southern extent than GFS based guidance. Will opt toward a blended solution with increase in shower and thunderstorm coverage along the front by Wednesday afternoon gradually becoming confined to southeastern portions of the forecast area through the day Thursday. With rather weak shear and significant overturning upstream, severe weather is not expected. Cooler and drier conditions will begin working in from the northwest Thursday with Friday looking like a fantastic late summer day. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... As of 735 PM Friday... Diurnal cu field continues to diminish with the loss of daytime heating and VFR conditions will remain through the remainder of the evening. Attention will then turn to the possibility of river valley fog overnight, especially after around 07Z. There does remain uncertainty in the extent of the fog potential though as high level clouds may move in ahead of a convective complex that will develop in the central Plains. However, can't completely rule it out given the low level inversion and light flow, so expect IFR/LIFR conditions where fog does develop. Any fog that develops should dissipate after around 12Z Saturday, and VFR conditions will then rapidly return to the area. Diurnal cu field will then develop in the afternoon in response to daytime heating. In addition, showers and storms are expected to develop across the Ohio Valley late in the period, and may impact northern terminals by late Saturday afternoon. For now, will leave mention of VCTS at PKB towards the end of the period, but thunderstorm activity will be possible at other terminals as well. Outside of any convection, conditions will remain VFR through much of Saturday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing, duration, and coverage of fog tonight may 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 SAT 08/17/19 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 M M L L L L L L HTS CONSISTENCY H H H H H H M M L L L L BKW CONSISTENCY H H H H H H M M H H M L EKN CONSISTENCY H H H M M M L M M M M M PKB CONSISTENCY H H H H H H M M L L L L CKB CONSISTENCY H H H H H M M H M H L L AFTER 00Z SUNDAY... Morning valley fog with IFR conditions possible Sunday and Monday mornings. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...MZ/SL/99 NEAR TERM...SL/RG SHORT TERM...MZ LONG TERM...99 AVIATION...RG