Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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336 FXUS62 KRAH 230840 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 335 AM EST Mon Jan 23 2017 .SYNOPSIS... A potent low pressure system over the southern Appalachians will track east-northeast through the Carolinas today, then track off the Mid-Atlantic coast on Tuesday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 335 AM Monday... Through daybreak: In advance of the vertically stack cyclone over Northern GA, low-topped convection within the mid-level dry slot will pivot northward across the area as the occluded front along the NC/SC state line lifts north into Central and Eastern NC through daybreak. Elevated instability of 500 to 1000 J/Kg of MUCAPE will develop briefly across the area between 06 to 12z as tongue of 850- 700mb moist warm air advection lifts north into the area, and further aided by the proximity of the cold temperatures aloft and relatively steep mid-level lapse rates of 7.5-8.0 C/km. This may lead to a slight uptick in coverage and intensity, with some isolated elevated thunder possible across the NC Piedmont. Latest Rap tries to develop some very weak sfc base buoyancy ~100 J/Kg across the far southeastern zones over the next couple of hours, coincident with the lower 60s Td air. This will be the one area we will have to monitor for some weak rotation and possibly a weak isolated tornado. Today: Upper low will track eastward across southern NC through 00z, and off the NC coast tonight. In the wake of the occluded front lifting north into Virginia, we could see some breaks develop in the low clouds across the central and eastern zones during the mid to late morning hours, before the approach of the cold core aloft(-22 to -24C)and steep lapse rates aloft(7-7.5C/km) will support the re- development of scattered showers across the area, with best coverage and best chance for thunder across the far SE where stronger diurnal heating is expected. Given cold temps aloft, could see some small hail with any decent updraft. Highs ranging from mid 50s NW to lower 60s east. Tonight: Drier air filtering into the area with the departure of the system should lead to SW to NE clearing late tonight into Tuesday morning. Lows in the lower 40s NW to mid 40s elsewhere.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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As of 220 PM Sunday... Tuesday and Wednesday: Any lingering cloudiness Tuesday morning will be retreating rapidly to the northeast as the coastal low lifts up the mid Atlantic coast. Unseasonably mild temperatures will stay with us through mid week with copious sunshine and increasing heights as mid level ridging migrates across the area. Highs on Tuesday will range from the upper 50s north to lower 60s south, warming on Wednesday to the mid and upper 60s.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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As of 220 PM Sunday... A strong shortwave lifting out of a longer wave trof into the Great Lakes region will push a cold front across the mountains Wednesday night and rapidly east across central NC and out of the area by mid afternoon Thursday. This front will be accompanied by scattered showers and begin our transition to north west flow and attendant cooler temperatures for late week and through the upcoming weekend. Temperatures on Thursday will have time to warm to the mid 50s west to lower 60s east before the cooler air arrives, and we will really notice the end of our two week mild spell Thursday night as mins fall to near freezing in the northwest to mid 30s elsewhere. Northwest flow will produce dry, but much cooler conditions Friday through Sunday, with highs in the 40s each day. Mins Friday and Saturday night will range from 25 to 30.
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&& .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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As of 118 AM Monday... 24-Hour TAF period: Low-topped convection, mainly in the form of showers, will lift north across the area through 12 to 14z. Could see some isolated elevated thunder across the far NW Piedmont over the next couple of hours, while isolated surface based thunder is possible at KFAY. Ceilings are expected to remain IFR/LIFR through 12 to 15z. Easterly winds of 10 to 12kts will become southwesterly around daybreak as the occluded boundary to our south lifts north of the area. Conditions should improve to MVFR/VFR between 15 to 18z. However, as the upper low moves across the area, we could see another round of scattered low-topped convection. Cannot rule out some isolated elevated thunder at KFAY this afternoon, in closer proximity to the upper low. MVFR ceilings will linger into the evening before drier air begins to filter into the area from the southwest between 06 to 12z, bringing a return to VFR by Tuesday morning. Looking ahead: Ridging aloft and at the surface will produced VFR conditions Tuesday and Wednesday. A cold front will cross the region late Wednesday night/early Thursday, bringing with a chance of showers and sub-VFR ceilings to the area. VFR conditions should return late Thursday afternoon/evening.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...SMITH NEAR TERM...CBL SHORT TERM...MLM LONG TERM...MLM AVIATION...CBL

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