062 FXUS61 KRLX 161841 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 241 PM EDT Mon Sep 16 2019 .SYNOPSIS... Weak cold front crosses today with isolated showers possible. High pressure and upper ridge dominate the rest of the week. Another system due to approach for the end of the weekend. && .NEAR TERM /THROUGH TUESDAY/... As of 219 PM Monday... A wavy cold front stretches from northwestern PA into central OH and central IN, which is associated with a weak surface low in the northern Ohio Valley. The frontal boundary will continue to move ESE towards our region through the day as surface high pressure in Ontario builds into the region this evening and overnight. Upper level support associated with the front will be weak, but with the heating this afternoon and fairly steep low level lapse rates, a few short-lived showers may occur across the area. A few of these showers have already developed near the Tri-state region, but the majority of the impact in this area has just been an increase in mid- level clouds. Thus, thinking the fropa will mainly just result in a wind shift from near W winds ahead of the front to near NNW behind the front. The front will push through most of the area overnight into early Tuesday, but low level moisture lingering behind the front overnight may support the development of river valley fog throughout parts of the area as many locations decouple. There is uncertainty in the coverage of fog tonight given how dry the ground is and little to no moisture contribution from the ground, but with the subsidence inversion overnight and little to no flow, at least some fog appears possible. With surface high pressure north of the area on Tuesday, expecting mainly dry conditions throughout the day. However, have included slight PoPs in the forecast in the mountains as enough orographic lift and instability could support a few showers and an isolated thunderstorm threat. Elsewhere, subsidence aloft will keep the remainder of the area dry, but temperatures remain well above normal with highs expected to reach the mid/upper 80s. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 230 PM Monday... For the start of this forecast period a weak trough of low pressure will move off to the southeast. High pressures at the surface builds in from the north over the region on Wednesday. This will promote fair and dry weather for the rest of this period and into the next period. Temperatures will remain above normal and also on the decline with mid 80's for highs and 50's possibly into the 60's for lows into Thursday as a cooler airmass slides closer in to the area. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 240 PM Monday... With high pressure overhead planted at the surface along with an extensive broad upper level ridge acting as an omega block, nothing but fair weather is in the long term forecast. Dry, mainly clear skies along with very low probability for any diurnal convection will continue into the weekend. Temperatures will remain above normal in the mid to upper 80's and vary only slightly over the week. Low 90's in certain spots is not out of the question especially during the weekend. Night time lows will increase slightly from what has previously been observed, however will stay generally around the 60's for a greater part of the area. Some models hint on the high pressure finally breaking down and bring a system through sometime late in the weekend, although they disagree on timing. Decided to agree with central guidance and went with slight chance/chance POPs areawide for Sunday when the next system is anticipated. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... As of 126 PM Monday... Widespread VFR conditions are in place this afternoon with high pressure in control. Latest surface analysis shows a cold front across southeast OH and western PA, associated with a weak area of low pressure in the northern Ohio Valley. As this system moves to the east, the cold front will continue to moving SSE towards the area through the remainder of the afternoon and evening. Only real impact from this feature will be a wind shift from WNW ahead of the front to NNW behind the front. The cold front will push south of the region overnight, with high pressure in the Great Lakes quickly building int. Enough low level moisture may remain tonight to bring a risk of river valley fog throughout the area, perhaps bringing IFR/LIFR conditions to areas where fog develops. By mid morning on Tuesday, any fog that develops will dissipate and VFR conditions will return to the area. Diurnal cu field will develop Tuesday afternoon, but any flight restrictions aren't expected. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z TUESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Coverage of fog and timing 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. 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 M L HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY H H H H H H H H M M L L PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H M M AFTER 18Z TUESDAY... Early morning dense river valley fog possible each morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JZ/RG NEAR TERM...RG SHORT TERM...JZ LONG TERM...JZ AVIATION...RG