Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 211828 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 225 PM EDT Fri Jul 21 2017 .SYNOPSIS... A hot upper level high pressure will remain in place from the Plains eastward over our region into the weekend. A cold front will approach from the northwest late in the weekend into early next week as the high pressure breaks down over the region. && .NEAR TERM /THIS AFTERNOON THROUGH TONIGHT/... As of 1100 AM Friday... Heat advisory in effect for much of the eastern Piedmont, Sandhills, and Coastal Plain for heat indices of 105+ this afternoon. A chance of a few strong thunderstorms this afternoon at 20-30 percent. Temperatures were already at or approaching 90 for much of the Heat Advisory area, with the "cooler" NW Piedmont zones not really that far behind in the heat. Satellite data indicated some cumulus along the Piedmont trough and over the Blue Ridge. Otherwise, strong heating with sunny skies noted. Dew points were slowly mixing out from the 70s into the upper 60s in the rear of the Piedmont trough over the Triad, with "outrageous" dew points down east (81 at Goldsboro, 77 at Fayetteville, 77 at Smithfield etc.. Highs are expected to reach 95-99 this afternoon, with 100 around Fayetteville. Heat indices will approach 110 in the FAY and GSB areas. An Excessive Heat Warning may be needed later today if lows are still anticipated to remain 77+ overnight - with heat indices of near 110 again Saturday in these areas. The latest data analysis indicated a well defined surface trough stretching SW to NE across the Piedmont, or roughly from near Charlotte to Raleigh. It is along this boundary were isolated thunderstorms are favored to develop this afternoon. MLCapes of 2000+ J/KG and high freezing levels support mainly a gusty wind threat with any storm. Even within this favored zone near the trough, POP is no higher than 20-30 percent for any one given spot for a thunderstorm. The MCS tracking toward the central Appalachians from Ohio is expected to track ESE over WVA and western VA this afternoon. There is a potential for outflow from this feature to help initiate or even enhance the chance of diurnally driven thunderstorms over SW VA and possibly NW NC Mountains this afternoon. Some of the CAMS indicate the probability (30-40 percent) that the NW Piedmont may get in to some action by mid to late day. We are not currently in any outlook by SPC; however, any storms that form or move into the NW have the chance to be locally strong to severe given the available energy to work with. Convection chances are expected to drop off by mid-evening, but we will have to watch the development of upstream MCS activity later tonight. Lows will be in the 70s (80 around KFAY). && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 415 AM Friday... Mid level ridging begins to flatten on Saturday as a short wave and associated front drops out of the Ohio Valley and grazes the area Saturday night. Very warm airmass in place Saturday modifies further, with low level thicknesses inching up to near 1450M (a modest 4M warmer than today = perhaps a degree warmer), so will basically maintain persistence highs from 97-99 and anticipate our heat advisory expanded perhaps a county to the west. The front will be moving across the area late in the day, and will have 30% PoPs across the northern tier from mid afternoon through midnight, with potential for showers and isolated storms to persist overnight due to outflow propagation. Persistence mins in the mid 70s Saturday night. && .LONG TERM /SUNDAY THROUGH FRIDAY/...
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As of 225 PM Friday... Hot and humid airmass will remain over central North Carolina Sunday as a ridges remain centered near Bermuda and in the lower Mississippi Valley. Meanwhile a shortwave moving across Great Lakes Sunday into Tuesday will deepen a trough over the Northeast and mid Atlantic states allowing a cold front to move south into the North Carolina area. Temperatures will lower to near seasonal averages by mid week with additional cloud cover and convection. Another shortwave will move across the Great Lakes Thursday and Friday keeping the eastern trough in place. Maximum temperatures on Sunday are expected in the mid to upper 90s with heat indices approaching 105F in some locations. However there is a possibility that considerable high level moisture and resultnant cloudiness will keep temperatures a few degrees lower.
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&& .AVIATION /18Z FRIDAY THROUGH TUESDAY/... As of 125 PM Friday... 24 hour TAF period: Generally VFR conditions under high pressure will persist through the TAF period. There is a low probability (20- 30) for MVFR thunderstorm conditions between 20z and 00z/this evening. Outlook: Generally VFR conditions are expected Saturday. Scattered mainly diurnally driven convection is possible Saturday and Sunday, with MVFR to IFR conditions. An even better chance of storms are expected by early next week as a cold front moves into the area, along with morning stratus and/or fog. && .CLIMATE... RDU Records: Date | High Year | High Min Year ------------------------------------------ 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 ------------------------------------------ 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 ------------------------------------------- 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...
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NC...Heat Advisory until 8 PM EDT Friday for NCZ010-011-025>028- 040>043-075>078-084>086-088-089.
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&& $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...mlm LONG TERM...Franklin AVIATION...Badgett CLIMATE...RAH

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