728 FXUS61 KRLX 041849 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 149 PM EST Fri Dec 4 2020 .SYNOPSIS... Low pressure crosses south of the area today into tonight. A cold northwest flow may allow for light snow in the mountains Saturday/Saturday night. Dry but cold Sunday. && .NEAR TERM /THROUGH SATURDAY/... As of 925 AM Friday... Adjusted the sky grids over the mountains to completely overcast and made some minor changes to the max temperatures today. Light rain continues to stream in from southwest to northeast this morning, continuing through the day and shifting into the mountains tonight. As of 630 AM Friday... Upped POPs for our southwestern extent of the forecast area this morning as some observations denote that rain has started to reach the surface. This will continue to overspread portions east of the Ohio River Valley through the morning as surface low pressure strengthens south of the region. Also freshened up temperatures and dew points this morning. With rain already reaching the surface in the Beckley area, dew points were coming in higher than the previously drier solution made with the initial issuance. As of 220 AM Friday... A quiet night is in progress amid increasing mid to upper level clouds ahead of our next system, which is currently undergoing cyclogenesis in the Mississippi Valley. As surface low pressure develops to our south, the forecast area will find itself within the western periphery of the disturbance, which will be enough to enforce a washout for the end of the work week. Early morning forecast soundings suggest it'll still be a few hours before the lowest levels of the atmosphere moisten enough for precipitation to reach the surface. By daybreak, the first batch of rain will flow in from the Tennessee Valley and up through the central and eastern portions of the forecast area. As the low continues to intensify in the Carolinas and up into Virginia, jet dynamics aloft will aid in feeding likely POPs east of the I-77 corridor through the day and start of the overnight period. The center of the low will propagate along the eastern seaboard up into New England by the conclusion of the period. A cold front will follow in quick succession behind the departing low, sending a colder airmass down from the Great Lakes and tapering shower chances from west to east. Precipitation still residing over the higher terrain late tonight will change over to a mix of rain and snow showers heading into the weekend, with a measly half an inch to an inch of snow projected along the ridgetops. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 148 PM Friday... A complex upper level pattern is expected to develop late weekend and early next week and might support a light rain and/or snow event across the region late Sunday into Monday. On Sunday, an upper level low is expected to be moving eastward across the lower Mississippi Valley and a pair of shortwaves in the northern stream will be diving southward with the leading one moving from the northern plains towards the Ohio Valley and secondary shortwave dropping into the Great Lakes. The main question is whether these three features merge together and help support a deeper upper trough and associated surface low that may track across the southeast US, which would be a more favorable precipitation solution across the region and is what the latest ECMWF continues to suggest. However, the other scenario, which the latest GFS suggests, shows less phasing with these three features and thus, possibly resulting in a surface low that develops further east and ultimately less precipitation chances for our area. Given these scenarios, there still remains considerable uncertainty with the forecast in the late Sunday into Monday timeframe but it does appear that regardless of the outcome, overall precipitation should be fairly light if the more phased solution verifies. However, if this system materializes, light snow would be the dominant p-type Sunday night with temperatures well below freezing area- wide and since temperatures are expected to around 10 degrees below normal on Monday, we should remain snow in the mountains and possibly a rain/snow mix elsewhere. Thus, trends will need to be monitored in subsequent model runs before there is more confidence with this system. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... As of 148 PM Friday... An upper level trough across the eastern US will maintain below normal temperatures at the beginning of the long term period, but temperatures will gradually increase each day as the trough shifts east and an upper ridge moves in. As a result, high temperatures should return to near normal values on Wednesday and above normal values by Thursday. In addition, little to no precipitation chances are expected at this time as surface high pressure is expected to dominate the region through late week. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... As of 1250 PM Friday... Light rain continuing to overspread the region as a low pressure system passes through the Tennessee Valley. Overall, expecting deteriorating conditions as the lower levels of the atmosphere saturate and any light wind today going calm alter this evening into the overnight. IFR ceilings and IFR fog settle in primarily after 00Z Saturday give or take a couple of hours depending on site. A reinforcing weak front aloft will keep the low ceilings in place into Saturday after 12Z, although improvements to MVFR can be expected as of this issuance. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY... FORECAST CONFIDENCE: Medium to High. ALTERNATE SCENARIOS: Timing of sub-MVFR ceilings may vary in the forecast. Brief visibility restrictions could arise within heavier showers. 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 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY H H H H H H M H H H H L HTS CONSISTENCY M H H H H H H H H M H H BKW CONSISTENCY H H H H M H H M M H H M EKN CONSISTENCY H M L M H H H H M M H M PKB CONSISTENCY H H H H M M M M M H H H CKB CONSISTENCY H H M M M L H M M H H H AFTER 18Z SATURDAY... Periods of IFR conditions possible within upslope snow showers Saturday into Saturday night. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...26/RG NEAR TERM...26/MEK SHORT TERM...RG LONG TERM...RG AVIATION...26