Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 250801 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 401 AM EDT Sat Mar 25 2017 .SYNOPSIS... Bermuda high pressure will extend west into the Carolinas and VA through the weekend. A weakening upper level disturbance will cross our region on Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 950 PM Friday... Mid/upper level ridge centered over the region this evening will shift offshore overnight in advance of the closed cyclone advancing east across the southern central Plains. This will allow for a marked increase in high-level moisture from west to east after midnight, which based on IR imagery, be sufficiently opaque enough to impede radiational cooling. Mild overnight lows generally in the 50s(~ 7 to 10 F degrees above normal). Sfc ridge axis extending into the area from the parent high centered off the Carolina coast, should maintain it`s influence across the area overnight, which will result in only modest/marginal low-level moisture recovery overnight, and thus should further limit fog development. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
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As of 400 AM Saturday... The upper low over the southern Plains states will lift to toward the Great lakes and weaken today through Sunday, while a Bermuda High continues to provide a warm southerly wind over the Carolinas. Ongoing convection in the Southern Appalachians Sunday morning should weaken as it moves out ahead of the primary cold front and the upper low, while becoming negatively tilted, weakens and passes well to our northwest. Aside form the western Piedmont, where 40-60m height falls appears to erode a fairly stout capping inversion, the rest of central and eastern NC remains capped by the sub-tropical ridge. Models continue to trend drier for most of central NC, and POPs have been adjusted down to just a chance west of US 1 on Sunday. Widespread cloud cover and possible showers will likely hold temps back a little in the west, but southerly flow should still allow highs to reach the mid 70s in the east. Models cranks out some light qpf Sunday night, but this looks over done, and stratus looks to be the only really issue, with mild lows in the mid and upper 50s.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/...
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As of 400 AM Saturday... With split flow persisting over the western US, yet another shortwave is forecast to eject east across the Mid-South Monday and Tuesday. Better destablization is expected each day as the low-levels continue to moisten around the Bermuda high, though limited forcing makes it hard to see more than isolated showers and storms on Monday. The relatively weak upper wave will cross NC late Monday night and Tuesday, and should result in a better chance of storms as it interacts with better instability on Tuesday. Highs both days will be in the upper 70s to lower 80s. The ridge aloft will then build back over the region Wednesday ahead of another upper low moving into the central Plains. meanwhile, a cold front is progged to push backdoor into NC Wednesday night and Thursday on the heels, though its still unclear how far south the front will get given the presence of the upper ridge. the GFS is much more aggressive with the front but also has a much more amplified northern stream flow. Temps will be knocked back into the 60s and lower 70s, with a possible cold air damming scenario setting up as high pressure migrates across the Great Lakes and the aforementioned low pressure system moves through the Midwest.
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&& .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... As of 215 AM Saturday... VFR conditions are expected for most of the TAF period, with a couple of exceptions. The first will be a chance of radiation fog around daybreak at RWI and FAY, where winds will be lightest in proximity to offshore high pressure, and also where surface dewpoints around 50 degrees are maximized relative to areas to the west. In addition, morning to midday heating of a seasonably moist air mass around Bermuda high pressure will favor the development of a field of stratocumulus that will initially develop around 2500- 3000 ft, and may be briefly broken at that time. Otherwise, SSWly surface winds will increase into the 6-12 kt range after 14Z, with occasional gusts into the teens kts, then lessen after sunset. Outlook: Late night-early morning fog and/or stratus, then MVFR range cloudiness as that moist layer is heated through midday, will be possible each day through early next week. Otherwise, a chance of showers and associated sub-VFR conditions mainly at Piedmont TAF sites will exist Sun, then again forecast area-wide on Tue. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...CBL SHORT TERM...SMITH LONG TERM...SMITH AVIATION...MWS

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