Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 131718 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 120 PM EDT Sun Aug 13 2017 .SYNOPSIS... A cold front will stall across the southern counties of central NC today, and remain quasi-stationary through the middle of the week. && .NEAR TERM /THROUGH TONIGHT/... As of 1240 PM Sunday... For the mid day update, adjusted max temps down a tad across the north. Presence of a low cloud deck and light ne sfc flow will likely result in afternoon temperatures across sections of the northern coastal plain and far northeast Piedmont in the 70s to near 80. Little if any adjustments required to the near term forecast. Also, due to the presence of this stable air mass, have lowered PoPs a bit across the northern third of the forecast area. Across the south, partial has warmed temps well into the 80s. Afternoon highs in the upper 80s-lower 90s still appear on target. Sfc cold front has progressed swd into the Sandhills and southern coastal plain of central NC, a little farther south than anticipated 24 hours ago. This sfc feature will serve as a focus for the development of scattered convection this afternoon-evening. Thus will maintain likely PoPs over this region. Convection probabilities will likely increase across the northern counties after sunset as a weak upper level perturbation passes overhead, initiating/sustaining a few showers and storms. Similar to Saturday, enough wind shear exists in the atmosphere to cause the convection to organize into random supercells or broken bow segments. While torrential rainfall will be the main weather hazard through tonight, an isolated strong/severe storm cannot be ruled out, primarily along and immediately behind the stalled sfc front. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... As of 400 AM Sunday... The models continue to depict the front becoming quasi-stationary across south-central NC, perhaps slightly farther south than previously indicated, through early in the upcoming week. Continued high precipitable water values in excess of 2 inches, frontogenetical forcing (including convergence), and isentropic upglide atop the front, will favor a continued high chance to likely probability of showers and storms. Generally persistence temperatures in the middle to upper 80s, with perhaps some lower ones over the nrn Piedmont (on the "cool" side of the front), and with still muggy lows in the lower to middle 70s. && .LONG TERM /TUESDAY THROUGH SUNDAY/... As of 325 AM Sunday... There is still quite a bit of uncertainty with respect to rainfall chances/amounts for this part of the forecast, resulting in below average confidence. Generally, expect the climatological diurnal convection through the period (higher chances during the aft/eve, general lull overnight into the early morning hours. The upper level pattern will be characterized by high pressure over the deep south and weak cyclonic flow over and north of Central NC. A tropical cyclone could be off the NC coast on Tuesday, but should stay over the Atlantic, recurving away from the Carolinas. At the surface, expect the usual trough to hold over the region for much of the period. An upper level disturbance could swing through the Great Lakes and Ohio Valley over the weekend, possibly yielding an increase in convection over the area. Temperatures, hovering within a couple degrees of normal through the period. Highs will increase from mid 80s on Tuesday to near 90 degrees by the weekend. Lows will generally range from upper 60s to mid 70s through the period. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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As of 120 PM Sunday... A moist and unstable air mass coupled with a series of upper level perturbations will cause episodes of scattered showers and thunderstorms across central NC through Tuesday. In vicinity of the heavier showers and storms, low end MVFR or IFR parameters will likely be encountered. Due to the presence of the very moist air in the lower levels of the atmosphere, there is the high likelihood of late night/early morning low clouds and/or fog through mid week. The weather pattern is not expected to change much this week. This suggest a continued high probability of sub VFR parameters through Friday, mainly in the form of late night/early morning low clouds and fog and associated IFR/LIFR parameters, and scattered afternoon- evening convection.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...WSS SHORT TERM...MWS LONG TERM...KC AVIATION...WSS

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