Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 170732 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 330 AM EDT Tue Apr 17 2018 .SYNOPSIS... An area of high pressure will drift east from the northern Gulf today to a position off the FL peninsula on Wednesday. Meanwhile, a series of strong low pressure systems will track from the upper Midwest into New England. The difference in pressure between the high to our south and the lows to our north will create breezy conditions across central NC through Thursday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 330 AM Tuesday... Cyclonic flow around a deep upper level low over the eastern Great Lakes into New England will maintain breezy and seasonably cool conditions across central NC today. Perturbations in the flow interacting with available moisture in the 4000-8000ft layer will cause periods of patchy stratocu, primarily across the northern counties. 850mb thermal trough over the region this morning will lift nwd later today as the upper level low also lifts nwd into southern Quebec. Low level thickness 40-50m below normal supportive of afternoon temperatures a 6-9 degrees below normal for mid-April. Highs this afternoon should vary from around 60 across the far northern coastal plain to the mid-upper 60s elsewhere. Sfc winds will remain gusty due to the pressure difference between the deep low well to our north and the area of high pressure residing over the northern Gulf. Wind gusts 20-25 MPH should be common with isolated gusts near 30 MPH. Tonight, mostly clear skies in the evening will giveway to partly cloudy skies overnight as a low level warm air advection commences. Low level winds will gradually back to a west-sw direction. This pattern will support min temps several degrees warmer than current overnight readings. Min temps generally 40-45 degrees.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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As of 330 AM Tuesday... Wednesday through Thursday, the atmosphere will remain relatively dry and stable, leading to a dry forecast. The stout sw flow Wednesday will usher a much warmer air mass into the region. Aloft, heights will be rising as the upper level low over New England lifts into southern Quebec. The modifying air mass will lead to temperatures slightly above normal, ranging from the upper 70s north to the lower 80s south. While sfc winds will generally be less than 10 MPH int he morning, a tightening sfc pressure gradient should yield sfc wind 10-15 MPH later in the afternoon with gusts around 25 MPH. These winds in conjunction with minimum rh values in the upper 20s-lower 30s across the southern counties may lead to enhanced fire danger conditions. A dry cold front will move sewd across central NC late Wednesday night-Thursday morning, being propelled aloft by a s/w crossing southern New England. The breezy conditions will continue Wednesday night into Thursday, drying the fine fuels even more. While cooler air will overspread the region from the NW Thursday, lower dewpoints will lead to minimum rh values in the afternoon close to 25 percent. The low rh combined with gusty winds between 25 and 30 mph will lead to another afternoon of enhanced fire danger. High temperatures Thu will vary from the upper 60s/around 70 NW to the upper 70s SE. Sfc winds will subside Thursday evening under clear skies as high pressure builds into central NC from the west. Min temps in the low- mid 40s.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/... As of 250 AM Tuesday... The upper-air pattern at the beginning of the long term period on Friday features a broad trough over New England with another trough and closed low over the four corners region with ridging in between across the Plains states. The eastern U.S. trough axis will be pushing off the mid Atlantic coast on Friday morning and central NC will experience a northwest flow aloft for Friday into Saturday. This pattern typically supports dry weather and cooler than normal temperatures. The surface pattern will feature a cool 1034MB surface high pressure system centered over the northern Plains on Friday that will shift east into the eastern Great Lakes on Saturday and then ridge into the Mid-Atlantic. The resulting sensible weather on Friday and Saturday will include mainly clear skies, dry weather, and temperatures between 5 and 10 degrees below normal. The upper trough and embedded closed low over the southwestern U.S. pushes east and reaches the southern Plains on Sunday and the Deep South on Monday as the narrow ridge axis reaches the Carolinas late Sunday and early Monday. NWP guidance is in better agreement with the overall pattern and timing which is a little slower than guidance from previous days. This should result in dry conditions on Sunday and through a good part of Monday. As the surface high to our north shifts off the New England coast, a weak surface low associated with the upper-trough will push east across the Deep South/Gulf Coast region late Sunday and Monday. This will allow an easterly flow to develop across the Carolinas on Sunday into Monday with a breezy and cool northeast winds expected by Monday. Given the placement of the surface low, central NC will remain on the cooler and more stable portion of the storm system. The resulting sensible weather will feature increasing clouds on Sunday with mostly cloudy conditions expected by late afternoon with considerable cloudiness persisting into Monday. Dry weather is expected on Sunday with a chance of showers arriving across the southwest and southern areas Monday morning with rain chances increasing slightly and spreading north on Monday night. At this point, the greatest precipitation chances and amounts through Monday night will be located to our south in SC, GA, and FL. Morning lows on Sunday will range in the mid 40s with highs in the mid 60s to around 70. Lows on Monday morning will be moderated by the cloud clover and stirring wind with lows in the upper 40s to lower 50s and highs in the lower to mid 60s. -Blaes && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... As of 250 AM Tuesday... There is a high likelihood that VFR conditions will persist across central NC through Wednesday afternoon. Wly sfc winds will be breezy, especially during the late morning and afternoon hours, with gusts 22-27kts common today and Wednesday. VFR parameters are expected to persist into the weekend. A dry cold front will progress southward across central NC late Wednesday night through Thursday morning. The atmosphere during the time of frontal passage appears too dry and too stable to support anything more than a few clouds. It will remain breezy with gusts around 30 kts probable on Thursday. A lighter wind regime anticipated Friday into Saturday. && .RAH WATCHES/WARNINGS/ADVISORIES...
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Frost Advisory through 9 AM EDT this morning for NCZ007>010- 021>026-038>041-073>076-083.
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&& $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...Blaes AVIATION...WSS

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