Area Forecast Discussion
Issued by NWS Charleston, WV

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701 FXUS61 KRLX 271454 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1054 AM EDT Thu Apr 27 2017 .SYNOPSIS... A cold front crosses late today and this evening. Weak high crosses Friday morning. A front sags into the area and then retreats this weekend. A stronger cold front crosses Monday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1050 AM Thursday... Surface analysis shows pre-frontal pressure trough, over central KY this morning. Just to the west lies a vigorous cold front approaching from the west. The past few radar scans show a line of convection forming up in vicinity of Lexington KY. Expect this line to continue to progress to the east today. Moderate instability and shear profiles support linear convection with some multicellular development with gusty winds being the main threat. Current forecast trends on track with only minor tweaks made to forecast. As of 545 AM Thursday... Showers and thunderstorms are likely today, as a cold front approaches from the west-southwest. The front was just east of the Mississippi River early this morning, with convection ahead of it along the nose of a jet max through the base of an upper level short wave trough, pushing into eastern Tennessee early this morning. The cold front is progged to move through late this afternoon and this evening, as the short wave trough lifts through the middle and upper portions of the Ohio Valley. Meanwhile, the jet max approaches, but remains mainly southwest of the area through tonight. All of this places the timing of the showers and thunderstorms moving west to east across the area squarely on today, with the forcing weakening late. CAPE is progged to reach 1500 J/kg ahead of the front. Deep layer shear is impressive, exceeding 80 kts in the 0-8km layer, but the effective inflow layer is limited by a relatively stable layer about h9-h9, thus limiting the effective bulk shear. Midday through mid afternoon across central and eastern portions of the forecast area appear to carry the best potential for strong wind gusts and small hail. Clearing takes place behind the cold front tonight, as high pressure builds in toward dawn. Fog is likely to form toward dawn as the boundary layer becomes calm, with low clouds possible in the mountains. Adjusted temperatures today to get highest values ahead of precipitation. Faster timing of the front, and associated precipitation result in slightly lower highs than previous forecast. Lows tonight are close to latest guidance as well as previous forecast.
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY/... As of 545 AM Thursday... High pressure Friday, with dry and warmer conditions, with warm frontal boundary lifting north across the region. The warm frontal boundary will linger across the Ohio Valley during the weekend, with periods of showers and thunderstorms, particularly across parts of southeast Ohio, with heavy downpours expected. In addition, some of the storms could be on the strong side late Friday night/early Saturday, with strong winds the primary threat, particularly across western zones. A slight risk is in place across parts of northeast KY, with a marginal risk across western 1/3 of CWA. Warm frontal boundary will continue to lift north over the weekend as upper trough across central U.S. continues to deepen. Showers and thunderstorms, along with increasing heat and humidity can be expected over the weekend as a result. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... As of 545 AM Thursday... Cold frontal boundary associated with the system will push through the region Monday and Monday night, with additional rounds of showers and thunderstorms, some of which will be heavy at times. Still a bit too early to pinpoint/determine any severe threat. Behind the front, cooler and unsettled weather takes hold for Tuesday, followed by another system by mid week. && .AVIATION /15Z THURSDAY THROUGH MONDAY/...
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As of 700 AM Wednesday... MVFR fog in the Tygart Valley will dissipate first hour of the forecast. A cold front approaching from the west is likely to bring showers and thunderstorms from west to east across the area late this morning through this afternoon. So far have coded VCTS / CB at this distance, but any thunderstorm can bring IFR conditions. Strong wind gusts and hail are also possible. Timing of the showers and thunderstorms is generally 16-21Z west, and 18-23Z east, although the actual window of precipitation should be no more than 3 or 4 hours at any one site. Clearing will take place behind the cold front tonight, although MVFR stratocu may linger in the mountains, and fog may form late. IFR is coded for CRW 09Z and EKN 11Z, when MVFR stratocu breaks up. South to southwest will be around 10 kts and gusty ahead of the cold front today, and then light west to southwest behind the cold front tonight, becoming calm overnight. Moderate south to southwest flow aloft today will become light to moderate southwest tonight. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY... FORECAST CONFIDENCE: Medium to high. ALTERNATE SCENARIOS: Timing and coverage of showers and storms, and associated MVFR or worse conditions, may vary today. Formation and then breakup of MVFR stratocu behind the cold front tonight may vary, as may fog formation late. Fog formation may depend upon dissipation of stratocu in the mountains. 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 M H H H H H H M HTS CONSISTENCY H H M H H H H H H H H M BKW CONSISTENCY H H H H H M L H H L H L EKN CONSISTENCY H H H H H H M H L H H L PKB CONSISTENCY H H H H M H H H H H H M CKB CONSISTENCY H H H H H M L H H H H M AFTER 12Z FRIDAY... IFR fog possible Friday morning.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...KMC/TRM SHORT TERM...SL LONG TERM...SL AVIATION...TRM

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