Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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208 FXUS62 KRAH 212244 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 645 PM EDT Sat Apr 21 2018 .SYNOPSIS... Chilly high pressure will extend south through the middle Atlantic states through the weekend. Low pressure is forecast to track east across the Gulf Coast states this weekend, then turn up the eastern seaboard early next week. This will bring cool and wet conditions early to mid week. && .NEAR TERM /THROUGH TONIGHT/... As of 100 PM EDT Saturday... Surface high pressure was centered from the eastern Great Lakes into the Delmarva and Outer Banks regions early this afternoon. The ridge axis extended down the eastern seaboard into GA and FL. High pressure will gradually move off the Mid-Atlantic coast tonight allowing some modification in temperatures. A few cirrus clouds, if any, is expected through tonight. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... As of 100 PM EDT Saturday... Forecast for Sunday and Sunday night remains on track. Surface high pressure is expected to be reinforced over the Great Lakes into New England, then down into the Mid-Atlantic states Sunday into Sunday night. This occurs as a "closed" circulation or mid/upper low will track east across the Gulf Coast states. There will be an increasing pressure gradient and wind associated with these features. There will be a very deep and moist sub-tropical connection that will be tapped and pulled NW into NC by late Sunday night as the mid/upper low approaches the TN valley region. Clouds will thicken and gradually lower Sunday night, as rain probabilities increase from the south and west. The rain should hold off until Monday, but areas near the NC/SC border may have some light rain or sprinkles after sunrise. Cloud cover will cap temperatures somewhat on Sunday, but keep them very mild Sunday night as the E-SE flow increases. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 400 PM EDT Saturday... ...Another widespread soaking rain expected Monday afternoon into Tuesday night... Compact closed upper level low over the Lower MS Valley Monday morning will drift slowly NNE across the TN Valley through Tuesday. In response to a pair of prominent shortwave troughs diving SE into the central and eastern US, the mature cyclone is forecast to undergo significant shearing Tuesday night, and will eventually open up into a trough as it ejects eastward through the Mid-Atlantic states on Wednesday. While strong mid/upper level ridging extending along the western Atlantic/Mid-Atlantic coast may initially delay the spread of rain NEWD into the area Monday, the widespread rain looks to set in area- wide by late Monday afternoon/early evening. Owing to the slow movement of the upper low across the region, along with a very strong Atlantic maritime feed into the area, central NC has the potential to see a widespread soaking of 1 to 2 inches, with localized higher amounts possible. With area rivers and creeks running high from recent heavy rainfall over the past week, this additional rainfall may be enough to result in some localized/minor flooding. Last few runs of the model guidance have indeed trended farther inland with a secondary/triple point low and occluded front across southern/southeastern NC Tuesday afternoon/evening. If models maintain this low track and sufficient buoyancy can develop(highly uncertain due to widespread rain and low clouds expected on Tuesday), will have to carefully watch the convection along the occluded front it moves into the region, as already favorable low- level shear/wind fields will be further enhanced by the wedge front lingering across the area. Have introduced a slight chance across the eastern Sandhills and southern coastal plain counties. Stay tune. The widespread rain chances should become more scattered Tuesday night and into Wednesday as the sheared/open trough remnants of the low move east through the Mid-Atlantic region. A series of shortwave trough diving SE within the broad mid/upper level troughing across the central and eastern CONUS will lead to a continued chance of rain/showers through the remainder of the work week. The widespread rain, low clouds and cold air damming over the NC Piedmont will keep temps on the cool side Monday and Tuesday, ranging from near 60 NW to o upper 60s/lower 70s SE. Gradual erosion of linger CAD and continued rain chances will result in slower moderation of temperatures into the 70s through the remainder of the work week. && .AVIATION /23 SATURDAY THROUGH THURSDAY/...
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As of 645 PM Saturday... 24 Hour TAF Period: High pressure centered over the Mid-Atlantic region will remain in control of the weather through Sunday, resulting in dry VFR conditions through the TAF period. Surface winds will remain variable and less than 10 knots. Outlook: A slow moving upper level low moving through the region will bring widespread MVFR/IFR VSBYS and CIGS in rain and fog across central NC Monday through Wednesday. Scattered showers and MVFR conditions are possible Thursday as a series of upper level disturbances move the region.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NC...None. && $$ SYNOPSIS...Badgett NEAR TERM...Franklin SHORT TERM...Badgett/Franklin LONG TERM...CBL AVIATION...CBL

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