Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 192312 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 712 PM EDT Wed Jul 19 2017 .SYNOPSIS... A weak upper level low over will drift slowly east and out into the Atlantic tonight. A hot upper level ridge will build east from the Plains to the Carolinas through Saturday, before breaking down Sunday and Monday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 710 PM Wednesday... The skies were generally sunny across central NC at early afternoon. The mid/upper weak low over eastern NC was finally being nudged eastward as strong high pressure over the Plains builds east. This subtle shift east with the old upper low has pulled the trough axis deep into the Coastal Plain, and had veered the wind in the mid levels to the NNW allowing for some mixing and drying from aloft to infiltrate the Piedmont and Sandhills regions. There was some mixing to the surface just in the rear of the trough over the NE Piedmont where RDU, Roxboro, Henderson and Chapel Hill reported dew points in the mid 60s). However, that mixing out is variable elsewhere and dew points were still 70+ at most locations. A few storms have developed along the Blue Ridge, moving south today with the weak northerly steering flow, with a noticeable lack of convection or even cumulus development over the east. Given the mixing in the north central Piedmont, we may very well see a minimum of convection there. This makes sense in the rear of the departing upper low. However, widely scattered to scattered pulse type storms are anticipated elsewhere. MLCapes on the order of 1500 to 2000 J/KG suggest fairly intense cores capable of gusty winds that may again produce some isolated wind damage. Some hail may also occur, but it is favored to be just below severe criteria in most cases. Highs in lower to mid 90s are favored. Convection will diminish rapidly by mid evening, with mostly clear skies overnight. Lows generally in the mid 60s over the rural Piedmont, ranging into the lower 70s elsewhere.
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&& .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 208 PM Wednesday... Heat and heat indices will start to become more of an issue Thursday as the upper ridge builds east. Mostly sunny to sunny skies are expected with only about a 10 percent chance of a storm at any one location. The increase in sun and lack of cloudiness will help temperatures reach the mid 90s (except lower 90s NW) Thursday. The dew points are expected to range in the mid 60s NW and 67-70 in the east during peak heating. This would give heat indices of 100 to 103 in the east, and 95-98 in the NW. A heat advisory is not anticipated Thursday. However, that should change Friday. Lows Thursday night are expected to be in the lower to mid 70s (as the dew points slowly come up). && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 208 PM Wednesday... An upstream ridge (over the lower MS river valley) and a downstream ridge (offshore the SE coast) extending into the Carolinas Fri/Sat will de-amplify Sun-Mon as an upper level ridge amplifies over the Intermountain West, cyclonic flow aloft strengthens across the OH/TN valley and Mid-Atlantic, and a closed low retrogrades westward along the Gulf coast. Fri-Sat: Expect temperatures several degrees above normal Fri/Sat, with heat indices ~105F (primarily Triangle south/east), depending on surface moisture/dewpoints. Heat advisories may be needed for portions of the area Fri/Sat. With westerly flow aloft over the central Appalachians and a lee trough extending southward through central VA/NC in the midst of moderate diurnal destabilization, expect a potential for scattered convection during the afternoon and evening hours Fri-Sat, though activity could be suppressed over eastern portions of the state depending on the strength/orientation of the offshore ridge. Sun-Wed: Above normal temps/humidity may persist into Sunday, though chances for convection will also increase as cyclonic flow aloft strengthens over/upstream of the Mid-Atlantic. With an unseasonably complex synoptic pattern over the mid-latitudes, uncertainty increases significantly by early/mid next week. At this time, will indicate near normal temperatures and near climatological chances for convection Mon-Wed, in assoc/w a synoptic pattern generally characterized by ridging over the western CONUS and troughing over the eastern CONUS. -Vincent && .AVIATION /00Z THURSDAY THROUGH MONDAY/...
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As of 710 PM Wednesday... 24 hour TAF period...Isolated shower/storm near KINT will weaken and dissipate with loss of heating at or shortly after sunset. Otherwise, zone of subsidence in the wake of the broad upper low/trough moving off the SE coast will result in generally dry VFR conditions are expected tonight through Thursday. A lee side trough east of the will support light winds through the period. Outlook for Friday through Monday... Generally VFR conditions are expected Friday and Saturday. Scattered PM thunderstorms may return Sunday and Monday with associated MVFR to IFR conditions.
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&& .CLIMATE... RDU Records: Date | High Year | High Min Year ------------------------------------------ 20 July | 102 1942 | 76 1981 21 July | 102 2011 | 78 1932 22 July | 103 2011 | 78 2011 23 July | 105 1952 | 78 2011 24 July | 101 2011 | 79 2011 GSO Records: Date | High Year | High Min Year ------------------------------------------ 20 July | 100 1977 | 75 1986 21 July | 102 1926 | 76 2011 22 July | 101 1926 | 77 2011 23 July | 99 1952 | 78 2010 24 July | 99 1914 | 78 2010 FAY Records: Date | High Year | High Min Year ------------------------------------------- 20 July | 104 1932 | 80 1996 21 July | 105 1932 | 79 1977 22 July | 107 1932 | 79 2011 23 July | 103 2011 | 79 1998 24 July | 105 1952 | 79 1945 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...Badgett LONG TERM...Vincent AVIATION...CBL/Badgett CLIMATE...RAH

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