Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 231838 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 238 PM EDT Sun Apr 23 2017 .SYNOPSIS...
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Upper level low passes to our south tonight and then swings east to the Carolina coastal states Monday, keeping rain mainly in the south and east through Monday. Warmer midweek before a cold front crosses Thursday night.
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As of 200 PM Sunday... While there are typical model differences in the exact handling of the broad upper low currently over the western Tennessee valley this period, all are indicating SIMILAR main effects for our area. The associated rain shield just over our southern most zones early this afternoon will struggle to shift northward this afternoon and evening. As the upper low slides south southeast into the southeastern states tonight, the rain shield will tend to shift slowly eastward and spread up the WV mountains. This process will continue Monday as the upper low then reaches the Southeast coast. By Monday afternoon, most of the rain will have shifted into the mountains. Thus, will keep the northwest half basically dry and the southeast quite wet, with a tight POP gradient in between. In addition, the good influx of moisture and steady but persistent rain over the southern mountains will validate continuing the Flood Watch as is, with flood warnings already in effect for SW VA. The watch may very well have to be extended and expanded up the mountains later tonight and Monday, but there is enough uncertainty in the exact track of the upper low and the axis of heavy rain for further evaluation. Otherwise, look for coolest temps tonight and warmest temps Monday over northwest portions of the area given less thick clouds and lack of rain.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 420 AM Sunday... Stacked low pressure system tracks slowly eastward across the carolinas Monday through Tuesday, and then northward along the middle Atlantic seaboard Tuesday night through Wednesday night. What is left of the deformation zone near the diffluent region northeast of the upper level low moves northward through the forecast area Monday, returning the chance for showers across much of the WV lowlands. Showers should become increasingly confined to the eastern slopes of the central Appalachians Monday night and Tuesday, as the system shifts east. High pressure anchored over New England, and low pressure over the upper midwest, combine to configure a cool air damming wedge, resulting in moist upslope flow along the eastern slopes of the mountains. This will keep that area socked in with low clouds and light rain and drizzle. This pattern gradually breaks down later Tuesday into Tuesday night, as the pressure gradient from the low to the west moves in and establishes a southerly flow. Wednesday and Wednesday night will be warm and mainly dry in the southerly flow, as a cold front associated with the low pressure system to the west only slowly approaches. The chance for showers is introduced in the middle Ohio Valley by dawn Thursday, as that front gets closer. No adjustments were needed to central guidance temperatures and dew points, with a warming trend that takes temperatures back above normal. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 420 AM Sunday... Models were generally in agreement on a cold front approaching Thursday and then crossing Thursday night, bringing the chance for showers and thunderstorms, the thunderstorm chance also diurnally driven. The front weakens thereafter, becoming oriented west to east and drifting back over the area Friday. A chance for showers and afternoon thunderstorms are in the forecast for Friday as a result. Models diverge for next weekend on how quickly that front pushes northward, and the area breaks out in the warm sector, and how quickly the next cold front approaches from the west. This will depend upon the strength and positioning of upper level ridging along or off the east coast. A low chance for showers and mainly diurnally driven thunderstorms remain in the forecast as a result. No changes to central guidance temperatures, with lowland highs generally holding in the lower 80s. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... 18Z Sunday thru 18Z Monday... As of 1145 AM Sunday... Quite a gradient of Flight Categories this period. Upper level low currently centered over the Tennessee Valley will slowly drop south and east this afternoon and tonight. However, it is broad enough to pull deeper moisture and widespread rain northward into parts our area this afternoon and tonight. Northern edge of rain by 00Z will be just south of HTS-CRW-W22 line with the south quite wet and the north remaining dry. Tonight will see this rain shield shift toward the east and expand up eastern WV, with the back edge of the rain mainly along and east of a CRW-CKB line by 14Z. Look for VFR ceilings to mostly persist outside of the precip shield this period, mainly at PKB and CKB. Mostly MVFR/IFR IN the precip shield, with MVFR prevailing at HTS,CRW, and possibly EKN. IFR/LIFR in the southern and central mountains including BKW. Wind will be easterly at 5 to 10 KTS, except 10 to 20 KTS higher mountain elevations. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY... FORECAST CONFIDENCE: Low to Medium. ALTERNATE SCENARIOS: A minor shift in the upper low movement may greatly affect timing and development of rain across the area. 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 M M M M M M M M M M M L HTS CONSISTENCY H H M M M M M M M M M L BKW CONSISTENCY L L L L L L L L L L L L EKN CONSISTENCY H H H H H H H H M M M L 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 MONDAY... IFR possible into Monday with another wave of low pressure. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flash Flood Watch until midnight EDT tonight for WVZ033-034. OH...None. KY...None. VA...Flash Flood Watch until midnight EDT tonight for VAZ003-004. && $$ SYNOPSIS...JMV/26 NEAR TERM...JMV SHORT TERM...TRM LONG TERM...TRM AVIATION...JMV is the U.S. government's official web portal to all federal, state and local government web resources and services.