343 FXUS61 KRLX 171005 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 605 AM EDT Fri Mar 17 2017 .SYNOPSIS... High pressure exits first thing this morning. Warm front late today, followed by a cold front late tonight into Saturday. Disturbance Saturday into Saturday night. && .NEAR TERM /THROUGH TONIGHT/... As of 600 AM Friday... Temperatures continue to run a little low early this morning. Forecast otherwise appears to be on track including timing of precipitation. As of 225 AM Friday... High pressure exits first thing this morning. An upper level short wave trough digs east-southeastward through the midwest today and tonight, and becomes a closed upper level low overnight tonight. This drives a surface warm front through the area late today into tonight, and then a surface cold front into the area late tonight. A narrow north-northwest to south-southeast oriented band of precipitation was having trouble reaching the ground south of Chicago early this morning, where the band was thinnest. The models appeared to have a good fix on this precipitation entering the area during the daylight morning hours, the band widening in an area of developing warm advection / isentropic lift. The only gradually increasing PoPs reflect the precipitation having difficulty reaching the ground early on, with rain becoming likely from west to east across the area this afternoon. Blended in the latest MET and short term consensus into the previous forecast, which already looked reasonable, for temperatures and dew points today and tonight. These temperatures and model fields suggest temperatures climb above freezing at the surface before doing so in the elevated warm wedge, which should mitigate the chance for freezing rain. Instead, a light mix of snow and sleet may or may not measure this morning, before the transition to rain this afternoon, when measurable precipitation becomes likely. A slower rise in surface temperatures than forecast could increase the chance for freezing rain today. The daytime timing in mid March does not favor freezing rain but, if precipitation is able to reach the ground early this morning, then the chance for freezing rain could increase. As the cold front pushes into the area late tonight, drier air arriving aloft will eliminate ice crystals and, with surface temperatures above freezing through the night, the diminishing showers should remain in the form of rain in the wake of the cold front over the middle Ohio Valley. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... As of 225 AM Friday... Cold front just to the east of the CWA at the start of the period, with gradually cooler weather taking hold. Light snow shower activity will kick off particularly later in the day Saturday and Saturday night, as a northwesterly upslope flow, and several upper impulses rotate around the back side of an upper low, which will be moving across the Great Lakes region towards the east coast. At this point, figuring mainly light accumulations across the northern mountain zones, with little to no accumulations across the lowlands, with the bulk of accumulations expected Saturday night and Sunday. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 225 AM Friday... High pressure with dry and warmer conditions to start next week, Another cold front will sweep across the area by Monday night, with rain showers developing area wide as it does so. Frontal boundary sags south by late Tuesday night, with high pressure building in across the north, with much drier air in place. There could be a rumble of thunder late Monday night/early Tuesday across far southwestern zones, but threat appears minimal at this point. A strong low pressure system is progged to move into the area by late next week, with the potential for heavier rains, and thunderstorms. && .AVIATION /10Z FRIDAY THROUGH TUESDAY/... As of 600 AM Friday... After a VFR start, a warm front will bring lowering ceilings today, along with precipitation that may start briefly as a mix of snow and sleet, before transitioning to all rain. By the time the probability of precipitation is high enough to code up explicitly in the TAFs this afternoon, it should be in the form of all rain. Visibilities are likely to drop to MVFR in rain late this afternoon into this evening. Later tonight, the combination of the warm front moving through, and the loss of daytime mixing, is likely to result in MVFR ceilings. Ceilings may drop into IFR overnight tonight in the mountains, and in the PKB area of the middle Ohio Valley. A cold front will move into the area late overnight. More widespread IFR conditions are likely behind it. Light and variable surface flow ahead of the warm front will become light southwest behind the warm front late today and tonight, followed by a subtle shift to light west to southwest as the cold front crosses toward dawn Saturday. Light west flow aloft early this morning will become moderate southwest later this morning, and then moderate west tonight. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY... FORECAST CONFIDENCE: High early on, then becoming medium by late today. ALTERNATE SCENARIOS: Timing of precipitation and associated category changes may vary. If confidence increases, may need to add a brief period of wintry mix at the start of the precipitation today. Timing and extent of IFR ceilings tonight may vary, and some IFR visibility cannot entirely be ruled out. 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 FRI 03/17/17 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EDT 1HRLY 23 00 01 02 03 04 05 06 07 08 09 10 CRW CONSISTENCY H H H H H H H H H H H M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY H H H H H H H H H H H M PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 12Z SATURDAY... IFR possible in in low clouds early Saturday morning, especially in and near the mountains. IFR also possible Saturday night into Sunday morning, in snow showers in the mountains, and in low clouds throughout the area. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...Freeze Warning until 9 AM EDT this morning for KYZ101>103-105. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM SHORT TERM...SL LONG TERM...SL AVIATION...TRM