Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 181757 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1257 PM EST Thu Jan 18 2018 .SYNOPSIS... With high pressure passing south of the area, a southwest flow will bring milder air today through the weekend, with a warm front passing Saturday. A cold front crosses late Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 900 AM Thursday... Sent a quick update to expire the wind chill advisory. Rest of package remains on track. As of 630 AM Thursday... Delayed clearing in the mountains until the low level moisture mixes out and the upslope component of flow diminishes later this morning. As of 350 AM Thursday... Arctic air mass, represented by high pressure over the southeastern states, modifies as that high drifts slowly eastward during the near term period, and beyond. In the meantime, a southwest flow of milder air had already become established over the forecast area, with rising temperatures over the hill and ridgetops early this morning. The stratocu in and near the mountains will be eradicated this morning, as the moisture mixes out, and the westerly flow there backs, diminishing the upslope component. The remainder of the forecast is dry with a mainly clear sky, with a dry column, even as upper level ridging gives way to a short wave trough passing by to the north of the area tonight. Temperatures do rise slowly today overtop the snow cover and beneath a low inversion, with wind chills rising above the -10F advisory threshold by 10 AM. Leaned on the lower side of guidance, with highs just making it above freezing across the southern lowlands this afternoon. It will be noticeably less cold compared with one of the coldest days of the winter Wednesday. Lows tonight close to the MET, except lower in the valleys, but not quite as low as the MAV. The persistent pressure gradient will make for only somewhat of a ridge / valley split tonight, as even the valleys are not likely to stay decoupled through the night. Lows generally in the teens, compared with the widepsread single digits of early this morning, reflect the ongoing retreat of the arctic air. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... As of 350 AM Thursday... Warm and mostly dry during the short term period with high pressure in control. A warm frontal boundary associated with low pressure moving northeast out of the Plains will lift north across the area late Saturday night into Sunday, with light showers forming as it does so. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 350 AM Thursday... Cold front associated with aforementioned low will sweep across the forecast area on Monday, with rain developing area wide. Good moisture fetch associated with system, with PW values progged to rise to around an inch, will result in decent rain totals, with qpf values around 0.75 inches or more area wide. Any lingering precipitation will change over to light rain and snow showers Monday night, continuing into Tuesday, with light accumulations possible. Wednesday looks to be dry with more seasonal temperatures. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 1245 PM Thursday... CAVU through the period. High pressure builds overhead to provide clear skies through the period. The GFS and NAM show H850 west southwest winds around 40 knots around 2000 feet. The NAM and RAP13 models suggest Boundary layered winds of 20 to 30 knots overnight. Expecting EKN site to decouple overnight to produce light to calm winds. These conditions could produce low level wind shear at EKN overnight and was included in TAFEKN starting at 05Z. For the rest of the sites, light to gentle flow with occasional gusty winds will reduce the threat for LLWS at other sites. Light southwest surface flow, west to northwest on the ridges, will strengthen and become a bit gusty this afternoon and evening, before becoming light again tonight. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE: Medium to high. ALTERNATE SCENARIOS: Timing of low level wind shear may vary. Low level wind shear could materialize at other sites if the lower atmosphere decouples. 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 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 18Z FRIDAY... None. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...ARJ/TRM SHORT TERM...SL LONG TERM...SL AVIATION...ARJ is the U.S. government's official web portal to all federal, state and local government web resources and services.