Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 262000 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 400 PM EDT Sun Mar 26 2017 .SYNOPSIS...
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Active, mild pattern continues in a parade of southern stream systems. One crosses this evening, followed by another Monday night and Tuesday, and then again Thursday through Friday.
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&& .NEAR TERM /THROUGH MONDAY/... As of 2 PM Sunday... The remainder of the afternoon will tell what comes of a negatively tilted trough axis pivoting through the middle Ohio Valley, and the left front exit region of a strong jet on the back side of the trough coming in close proximity of the diffluent area ahead of the trough axis. So far, only small breaks in the cloud cover have limited surface heating. Heating was more evident farther south, beneath and behind the upper level trough axis, where the first thunderstorms were firing up in eastern Kentucky early this afternoon. The WRFs appear to have this pegged as the beginning of the main shower/thunderstorm activity crossing the area this afternoon into this evening, as the categorical PoPs in the forecast depict. The low level reflection of the upper level trough is a warm occlusion that will push through the area tonight. Loss of daytime heating should end the thunderstorm threat tonight, while the last of the showers should end once the occlusion pushes through. Compromised between the faster GFS, HRRR and RUC, and slower NAM and WRFs in winding down the precipitation overnight tonight. Models depict morning stratus where the surface occlusion stalls over the middle Ohio Valley on Monday. The next short wave trough brings an increasing chance for showers and thunderstorms from the southwest late Monday. Used a blend of near term guidance for temperatures and dew points, which did not bring up any major changes from the previous forecast. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
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As of 4 PM Sunday... Upper level southern stream short wave trough crosses Monday night and Tuesday, bringing the next round of showers and thunderstorms. However, the timing of the system is such that the strongest thunderstorms will be to the west of the forecast area Monday afternoon, and then to the east on Tuesday afternoon. The system pulls out Tuesday afternoon and evening, but is likely to leave low level moisture behind in the form of stratus overnight Tuesday night into Wednesday morning. High pressure sails across to the north of the area Wednesday, followed by a southeast flow developing in its wake by Thursday morning, beneath an upper level ridge. Temperatures close to central guidance and remaining above normal, even in the wake of the system midweek.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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As of 4 PM Sunday... The next southern stream upper level low approaches Thursday through Friday, before passing north of the area Friday night. This brings a surface warm front, along with an initial round of rain or rain showers, Thursday afternoon and evening. The surface cold front crosses Friday evening, as the surface low passes north of the area Friday night. Models have come in good agreement on this system. Showers and thunderstorms are most likely Friday into Friday night, but with the typical downslope shadow effect west of the mountains Friday in strong south to southeast flow in the warm sector ahead of the cold front. Northwest flow behind the system may bring upslope rain showers in and near the WV mountains on Saturday, with the latter part of next weekend more likely to bring dry weather. However, models are not too divergent on timing of yet another southern upper level low approaching late next Sunday. Temperatures close to central guidance and lower than the MEX.
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&& .AVIATION /20Z SUNDAY THROUGH FRIDAY/...
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As of 2 PM Sunday... A weak warm occlusion and upper level trough will continue bringing bands of showers through the area into this evening. Thunder is most likely to accompany these showers later this afternoon into this evening, especially in the middle Ohio Valley versus the central Appalachians. Brief MVFR conditions are possible in any of these showers and, of course, a heavier thunderstorm can always bring brief IFR conditions. The precipitation will diminish overnight tonight given the loss of diurnal heating, along with the causative upper level system moving out of the area. While areas of fog are possible where rain occurs, 15 to 20 kts of flow just above the surface should keep widespread IFR fog from becoming an issue. However, early morning IFR stratus is likely where it rains the most and a surface boundary stalls out, across the middle Ohio Valley. Have persistent stratus coded up for PKB overnight and Monday morning, and for CKB Monday morning. The rest of Monday morning and early afternoon will bring dry VFR weather, with at most a 4-6kft stratocu deck. Gusty south to southwest surface flow early on will tend to diminish later this afternoon, although gusts will remain possible in showers, and any thunderstorm can bring strong wind gusts, especially over the middle Ohio Valley later this afternoon. Otherwise surface flow will become light south tonight, and then light and variable on Monday. Light to moderate south to southwest flow aloft this afternoon into tonight will become moderate west to southwest early Monday morning, and then gradually become light southwest during the day on Monday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: May need TEMPO IFR in thunderstorms later this afternoon into this evening. There may be a bit more or less MVFR / IFR ceilings and visibilities overnight tonight and Monday morning and timing of improvement on Monday may vary. 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 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 CRW CONSISTENCY H H H H H H H H H H H L HTS CONSISTENCY H H H H H H H H H H H L BKW CONSISTENCY M H H H H H H H H H H L EKN CONSISTENCY H H H H H H H H H H H L PKB CONSISTENCY M H H H H M H H H H H M CKB CONSISTENCY H H H H H H H H H H H L AFTER 18Z MONDAY... Brief IFR possible in thunderstorms Monday night and Tuesday.
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&& .EQUIPMENT...
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Radar site KRLX has a faulty component that is leading to higher reflectivities than what should be observed at times. A part is on order and will be replaced as soon as it arrives. Keep this in mind since there is marginal potential for severe weather into this evening.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM NEAR TERM...TRM SHORT TERM...TRM LONG TERM...TRM AVIATION...TRM EQUIPMENT...TRM

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