344 FXUS61 KRLX 031737 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 1237 PM EST Tue Dec 3 2019 .SYNOPSIS... Large storm system pulls away today. Quick moving upper level system brings a cold front across Wednesday morning. Another system crosses Friday. High pressure Saturday. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 AM Tuesday... I let both the winter weather advisory and warning expire in the mountains as mostly snow showers persist there instead of freezing drizzle and reports were few and far between. Therefore, since impacts were minimal opted to let them both expire as scheduled. Snow showers do persist until that ridge finally builds in allowing dry air to entrain decreasing the moisture level. At that point, sometime in the afternoon, the area will dry out completely and become precip free. In the meantime, I also have modified and increased PoPs to represent the current trend of snow showers persisting in the lowlands and the mountains while changing the precip type to mostly snow with some drizzle to the west, on the backside of where the snow is falling, as the moisture column becomes more shallow thereby cutting off ice crystal growth and promoting drizzle. As of 635 AM Tuesday... Main update was to allow the Wind Advisory to expire as latest observations indicate that winds are below advisory levels. The rest of the forecast remains on track at this time. As of 428 AM Tuesday... Scattered bands of precipitation are evident on radar imagery this morning as upslope flow continues on the backside of an upper level low off the coast of southern New England. While precipitation activity at this point continues to diminish across the lowlands, still could see occasional periods of snow or a rain/snow mix through daybreak. However, precipitation will linger longer in the mountains, likely through at least late morning or early afternoon. Additional accumulations at this point will be light, with possibly a half inch to an inch in higher elevations and perhaps an inch and a half along some of the highest ridgetops through the early afternoon. In addition, there is some concern that chances for freezing drizzle will increase as the morning progresses as forecast soundings show a decreasing trend in moisture depth, leading to eventual uncertainties in the availability of ice crystals in clouds. Thus, decided to extended the winter weather headlines through 15Z (10 AM) given the freezing drizzle potential and travel impacts this could result in. Brief ridging will build in aloft this afternoon and bring an end to precip activity across the region. However, low level moisture will linger all day underneath a strong subsidence inversion, maintaining a fairly solid stratus deck. Given the low clouds and lack of solar insolation, temperatures this afternoon will be around 10 degrees below normal. Models show that the low clouds should start to scatter out by this evening, particularly across southern areas of the CWA. However, mid/upper level clouds will be increasing ahead of a shortwave trough that will be moving across the Great Lakes tonight. Moisture associated with this feature will be limited, but there will be enough to allow for slight/chance PoPs across northeastern areas of the CWA late tonight. This should result in areas of light snow showers across this area toward the end of the near term period, but the remainder of the area should be dry. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... As of 540 AM Tuesday... An upper level short wave trough drives a cold front through the area first thing Wednesday morning, and then crosses Wednesday. This sets up another upslope event for Wednesday into Thursday morning, although only seasonably chilly air follows the front. as such, a lack of ice crystals at times due to shallow moisture depth and / or low inversion spells freezing drizzle to go along with the light snow showers. With little moisture available to this system, snowfall will be considerably less than the event that is winding down this morning. High pressure builds toward the area from the southwest Thursday, only to slide off the mid Atlantic coast Thursday night. A northern stream short wave trough drives a cold front toward the area Friday, while a southern stream system slides south of the area just ahead of it. With the systems not phasing, limited moisture spells just the chance for rain mostly across roughly the southeast half of the forecast area. There could be snow at least mixed in if precipitation arrives early enough in the morning. The cold front sweeps through the area quickly enough to bring an end to any precipitation by the end of the day Friday. Central guidance temperatures accepted, with highs creeping back to normal and lows a little above normal. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... As of 540 AM Tuesday... A large high crosses the area Saturday morning, before moving off the middle Atlantic coast, allowing an increasingly warm and moist south to southwest flow to take over Saturday afternoon through Monday. Dry weather holds for most of the weekend, but rain showers arrive from the southwest late Sunday or Sunday night, likely bringing a wet start to the new work week. Several southern stream waves may then continue to bring rounds of rain showers, until a northern stream short wave trough finally drives a strong cold front through the area on Tuesday. Central guidance temperatures accepted. After a cold start under clear sky and light flow per high pressure Saturday morning, temperatures climb above normal through Monday, before dropping back with the passage of the cold front on Tuesday. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... As of 1235 PM Tuesday... Current CIGs will continue to lift by this late afternoon/evening and open up VFR conditions almost areawide overnight. The extreme northern side and near EKN/CKB will have periodic MVFR CIGs along with some VIS restrictions due to snow showers from earlier becoming reinforced with a trough passing by through the period. These showers will persist and promote even further drops in VIS by the early to late morning. Isolated IFR is feasible around these two sites and will continue through the day and may even worsen through the afternoon if showers progress. The rest of the terminals should remain dry although as the trough moves east lower CIGs will advect back into most of the lowlands causing CIGs to drop into the the MVFR to IFR range although will be temporary for just the morning into the early afternoon at which point the entire area lifts to VFR, besides the EKN/CKB area due to VIS. Light flow at around 5KT predominately out of the west will rotate to the west-northwest by late Wednesday morning and increase to around 5-10kt with gusts of 25KT+ areawide. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: Medium to High. ALTERNATE SCENARIOS: Fluctuations of cloud bases are likely Wednesday with the trough passing by. 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 17 18 19 20 21 22 23 00 01 02 03 04 EST 1HRLY 12 13 14 15 16 17 18 19 20 21 22 23 CRW CONSISTENCY H H H H H M H H H H H H HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY M L M M H H H M H H H H EKN CONSISTENCY H H M M M H H L H H H H PKB CONSISTENCY H H H H H M M M M H M M CKB CONSISTENCY H H H M M M H H H H H L AFTER 18Z WEDNESDAY... IFR in snow showers possible near the mountains Wednesday night, otherwise no widespread IFR expected at this time. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/RG NEAR TERM...JZ/RG SHORT TERM...TRM LONG TERM...TRM AVIATION...JZ