Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 200559 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 159 AM EDT Fri Oct 20 2017 .SYNOPSIS...
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A ridge of high pressure will extend across the eastern United States through the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/... As of 940 PM Thursday... Another night of calm winds and clear skies over central North Carolina. A slightly modified airmass that added a few degrees to our high temperatures today will do the same for the lows overnight. Expect most locations to bottom out in the 40s with some scattered upper 30s sprinkled in. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 245 PM Thursday... The strengthening high aloft and associated subsidence coupled with the sfc ridge will maintain a dry atmosphere across central NC Friday and Friday night. This dry air will support diurnal temperature swings of 30-35 degrees. The warming aloft in conjunction with the ridge at the surface will translate to mild afternoon temperatures in the mid-upper 70s, with a few locations across the far south possibly reaching 80 degrees. While temperatures will be in the 70s late Friday afternoon, the dry air in place will permit temperatures to cool into the 60s early Friday evening, and solidly in the 50s by midnight. Minimum temperatures in the upper 40s to around 50 should be common. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 255 PM Thursday... Mid-upper ridging now over the western Gulf will continue to amplify as it builds up and east across the Atlantic seaboard, to finally move off the coast late this weekend. Meanwhile, downstream lies a strong trof which is forecast to deepen as it moves east across the Plains, and we still have the potential for a cutoff low to separate from the trof over the Tennessee or the lower Mississippi valley Sunday night. If this low does indeed cut off (basically the GFS`s solution), it would enhance the chance for stronger, perhaps severe, convection in the Monday night/early Tuesday time frame. At the surface, high pressure over the mid-Atlantic states will gradually shift offshore, with return flow producing moisture advection and increasing cloudiness ahead of an approaching cold front Sunday night in the west, and spreading over central NC on Monday. Showers will become likely by late day Monday in the west, with likely PoPs spreading to the eastern Piedmont and Coastal Plain Monday night. Most of the convective activity will end by later Tuesday, with potential for some lingering instability showers in the cold air advection behind the front Tuesday night. Dry and cooler air will settle into place for midweek. Temperatures this weekend will be glorious for attending outdoor activities, with plenty of sun to accompany highs in the mid and upper 70s. Highs should also reach mostly mid to upper 70s on Monday with warm southerly flow to offset the lack of sun. Highs Tuesday should reach upper 60s to lower 70s, with the cooler airmass stalling highs in the 60s on Wednesday and Thursday. Morning mins will be in the low and mid 50s through Tuesday morning, with mins in the 40s on tap for Wednesday and Thursday. && .AVIATION /06Z Friday through Tuesday/...
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As of 155 AM Friday... High pressure building east across the middle Atlantic states, and associated strong radiational cooling and risk of "persistence" (relative to similar conditions 24 hrs ago) radiation fog at RWI this morning, will otherwise result in mainly clear, VFR conditions with light and variable to light n/nely surface winds, through the TAF period. Outlook: Continued persistence radiation fog will be possible mainly at RWI each morning through the weekend, followed by a higher probability of more-widespread sub-VFR conditions in stratus and fog, in increasingly moist east to southeasterly low level flow, Sun night-Mon morning. An approaching frontal system will then result in a good chance of sub-VFR conditions, showers and storms, and strong/shifting winds with height late Mon-Tue.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...Ellis SHORT TERM...WSS LONG TERM...mlm/MWS AVIATION...MWS

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