Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 202359 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 759 PM EDT WED JUL 20 2016 .SYNOPSIS... A strong upper level ridge over the central U.S. will expand east through the end of the week. && .NEAR TERM /THROUGH TONIGHT/... As of 320 PM Wednesday... A northerly wind across central NC suggests this morning`s cold front has slipped south across the SC border, but dewpoints remain rather high in the upper 60s and lower 70s over much of the piedmont and coastal plain. Richer boundary layer air lies across the Sandhills and southern coastal plain, where increasing instability, up to 1500 j/kg, and better low-level convergence will still support a few showers and storms through early evening. Tonight, another speed max crossing the Ohio valley will amplify south across NC, but with increasing stability and PW down to 1.25", the disturbance will largely have little impact over central NC. However, as previously noted, some weak moisture recovery over upstate SC and western NC may be enough for showers after midnight, mostly west of the Yadkin/Pee-Dee. Will maintain a slight chance POP along the far western CWA. Some patchy fog may develop given still elevated dewpoints, light wind and drier air just above the surface and statistical guidance/SREF probs show a little hint of some limited vsbys. Lows in the upper 60s and lower 70s. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... As of 320 PM Wednesday... On the heels of tonight`s upper disturbance, one more weak disturbance aloft will dive south across the area. Despite a slowly developing return flow, limited instability and moisture will inhibit anymore than just isolated convection over the western Piedmont, where weak theta e advection will be most prominent. 1000-850 mb thicknesses support highs within a degree or two of today`s highs, 86-91. Lows Thursday night again in the upper 60s and lower 70s. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 305 PM Wednesday... To begin the long term period, the region will be under northwest flow aloft as we remain between a strong upper ridge over the central conus and an upper trough over the Atlantic. However, the ridge will dampen some and start to spread east. Overall precip chances will stay rather low through the weekend, but will not be zero as there will be a persistent Piedmont trough that could be a focus for convective development, as well as any weak disturbances that move through in the northwesterly flow aloft. The bigger story will be the heat. As the aforementioned ridge spreads east, heights will rise over central NC. Max low level thickness values are progged to top out in the mid to upper 1440s (highest Saturday) and with temps not cooling off much as night, temps will be able to rise well into the mid 90s (maybe even some upper 90s). This combined with a moist air mass may necessitate the issuance of a heat advisory, most likely across the eastern half of the forecast area. The aforementioned ridge will shift even more over our region into early next week and possible offshore depending on which model you believe. Also, a shortwave trough is progged to cross the Great Lakes Monday into Tuesday. This will propel a cold front towards the region, but models are in general agreement that it will stay to our north. Regardless, with us gradually losing the influence of the upper ridge and with a cold front in the vicinity, precip chances will start to increase, at least back to the normal diurnal range. The increased cloud cover and precip chances should allow temps to "cool" back to the lower 90s, especially Tuesday and Wednesday. && .AVIATION /00Z WEDNESDAY THROUGH MONDAY/...
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As of 755 PM Wednesday... A few isolated showers will be possible this evening (best chance at KRWI). Otherwise, expect mainly VFR conditions with generally dry conditions and light and variable winds. However, the latest HRRR and statistical guidances indicates there is some potential for patchy low stratus and/or fog around sunrise, with the best chance east vs west. Will limit visbys in a tempo group around sunrise to MVFR conditions, except at fog prone KRWI (where we could see IFR/LIFR conditions). VFR conditions are expected during the day on Thursday, with a light southerly wind beginning to develop. Outlook: Sub-tropical high pressure will expand across the Southeastern U.S. and result in mostly dry/VFR, and increasingly hot conditions, through the weekend. However, a small chance of early morning fog/stratus, and isolated to widely scattered afternoon and evening storms, will be possible each day, but the probability of occurrence at any given TAF site will be quite low.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...BS NEAR TERM...BS SHORT TERM...BS LONG TERM...KRD AVIATION...BSD/BS

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