458 FXUS61 KRLX 061756 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 156 PM EDT Thu Jul 6 2023 .SYNOPSIS... Advancing cold front overnight into Friday brings unsettled weather. Another cold front brings more unsettled weather late Saturday through Sunday night. && .NEAR TERM /THROUGH FRIDAY/... As of 155 PM Thursday... Afternoon cumulus field has sprouted through the vast majority of the forecast area at the time of writing, with two areas that could produce showers and storms. The first being in a limited capacity and primarily diurnally driven along the higher terrain through this evening. Forecast soundings depict weak steering flow below 20kft AGL, imposing slow moving showers and storms in this part of the CWA. The more impressive activity noted on radar this afternoon stems from showers and storms preceding a cold front entering in from the west. Observations areas upstream of the Ohio River Valley have reported winds of 20-30 mph being produced within these storms alongside a quick dump of rain. Convection is expected to weaken on approach through the western extent of the forecast area this afternoon, especially as the sun sets for the day. The cold front sweeps into the region late tonight and continues its eastward progression on Friday. Shower and storm coverage will become contained to the Appalachian mountain as the front marches through, and will once again have a helping hand from daytime heating before sunset. Limited instability will deter much in the way of severe weather on Friday. Hot and muggy conditions reside over the area today, with several sports in the Tri-State already sneaking up to 90 degrees today. Very little reprieve is anticipated in the wake of the cold front Friday as highs soar into the mid 80s by the afternoon in the lowlands. High dewpoints will also yield continued muggy conditions as the work week wraps up. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... As of 310 AM Thursday... Any fog dissipates first thing Friday morning, and showers and thunderstorms refiring Friday afternoon will be most numerous in the mountains, as a cold front pushes east across the area. However, as the mid-upper level short wave trough driving the cold front through the area lifts through the upper Ohio Valley, meager forcing, light mid level flow and drying of all but the low levels should preclude both severe and excessive rainfall threats. With weak high pressure sailing by to the north, light flow surface and aloft is likely to lead to valley fog overnight Friday night into early Saturday morning, especially where it rains on Friday. How long dry weather lats into Saturday depends upon the timing of the next cold front approaching from the west, but a weak mid-level short wave trough ahead of the main short wave trough driving the cold front toward the area, should aid in at least afternoon pop-up showers and thunderstorms. The threat for strong, heavy storms may increase a bit along the western flank of the forecast area late Saturday, as the main short wave trough approaches, yielding a modest increase in flow/shear, and PW values. Central guidance reflects temperatures settling back to normal for Friday and Friday night as the cold front pushes east, and then a bit above normal ahead of the next cold front on Saturday. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 105 PM Thursday... A shortwave crossing to the south maintains precipitation chances on Monday, with greatest chances of activity expected to occur across the southern and eastern portions of the CWA. Following the exit of the shortwave early Tuesday, an upper low centered over Canada's Hudson Bay will keep the CWA on the periphery of a trough through mid week. During this time, high pressure will be present at the surface, though daytime heating should prompt convective development in the afternoon and evening hours. Models are hinting at the possibility of more widespread precipitation late in the work week as a shortwave swings through the upper trough, potentially bringing a front into the area. At this point, the timing and placement of this feature are uncertain; therefore, a blended solution has been maintained for the end of the long term period. Cloud cover and precipitation should result in cooler temperatures for Monday, then highs are expected to return to around normal for the rest of the long term forecast period. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 155 PM Thursday... Two distinct areas of showers of storms reside near the region this afternoon. The first being along the higher terrain where diurnally driven showers have begun to sprout within the cumulus field. Weak northeasterly steering flow aloft will direct vertically growing showers and storms at a sluggish pace through the afternoon, so mountain terminals will be spared from precip in the event activity does not form overhead or nearby. Radar trends in this part of the forecast area will quickly fizzle out with the loss of daytime heating. The better chance for convection encroaches from the west this afternoon as a cold front traverses the Ohio Valley. At the time of writing, a line of sub-severe storms were venturing into southeast Ohio and eastern Kentucky. Opted to include VCTS and tempo groups for PKB and HTS where storms could cross in close quarters to the airfield in the next few hours. As activity spreads eastward this evening, the loss of daytime heating will lower the potential for thunderstorms, but in the event healthier storms persevere into the central lowlands, additional tempo groups may be needed for other TAF sites. Precipitation associated with the cold front continues an eastward progression overnight, with ceilings gradually dropping to sub-VFR conditions after midnight. Calm column winds will support another round of river valley fog early Friday morning, with forecast soundings honing in on IFR or worse conditions at CRW and EKN. Surface vsbys improve after sunrise Friday morning, but lowered ceilings in the wake of the frontal passage will remain intact through the majority of the morning and early afternoon timeframe. Conditions gradually improve from west to east as high pressure settles in to round out the work week. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Additional tempo groups may become necessary this evening as showers and storms sweep through the area. 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 15 16 17 18 19 20 21 22 23 00 01 02 EDT 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22 CRW CONSISTENCY H H H H H H H H H H H H 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 H EKN CONSISTENCY H H H H H H H H H H H H 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 H H AFTER 18Z FRIDAY... IFR valley fog possible early Saturday morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/MEK NEAR TERM...MEK SHORT TERM...TRM LONG TERM...JLB AVIATION...MEK