Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 191427 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1026 AM EDT FRI AUG 19 2016 .SYNOPSIS...
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A series of mid-level disturbances will track across the Southern Middle Atlantic states, atop a lee surface trough through Saturday. A cold front will move through the area Sunday night bringing noticeably cooler and less humid air into the area for the first half of next week.
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As of 1026 AM Friday... A series or low-amplitude shortwave disturbances riding atop the flat subtropical high in place will continue to interact with the high PWAT airmass that stretches from the Southern Plain northeastward into the Southern Mid-Atlantic States. Coupled with weak low-convergence along a lee side trough that bisects Central NC, DPVA will support scattered to numerous showers and storms at anytime during the next 36 hours, though insolation in cloud breaks will yield moderate buoyancy this afternoon to support greatest coverage and storm intensity. While shear values are expected to range between 20 to 25 kts, sufficient to support a strong to severe cluster or two, weak mid- level lapse rates will hamper updraft strength. So, just like recent days, expect the severe threat to remain low with an isolated wet downburst possible. With PW`s again around 2 inches, locally heavy rain will be a threat, mainly in urban and poor drainage areas. Tempered by greater cloud cover, a couple degrees cooler than yesterday. Highs in the upper 80s to lower 90s. Lows in the lower to mid 70s.
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&& .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 330 AM Friday... More of the same is expected on Saturday as very little is expected to change in the overall setup. However, some model guidance does show a little bit drier air moving into northern portions of the area on Saturday morning/afternoon, which may limit coverage some on Saturday afternoon/evening across the far northern tier of the RAH CWA. Thus, will again go with the best chance across the southeast, with scattered showers and storms expected. Instability looks to be a bit more tempered on Saturday as well. Given this and only 10 to 15 kts of deep layer shear, expect chances of strong to severe storms will be low again, though heavy rain will again be a threat thanks to slow storm motion and still high moisture content air across the southern/southeastern half of the area. High temps on Saturday are expected to be in the upper 80s to around 90. Isolated to locally scattered showers and storms will again be possible Saturday night as additional disturbances track across northern portions of the area (though chances look smaller than tonight). Lows Sunday morning are expected to be in the lower to mid 70s again. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 335 AM Friday... A cold frontal passage late Sunday night into early Monday will bring a much anticipated change in the air mass across central NC in the form of a drier air mass and less humid conditions. Sunday... a moist and unstable atmosphere ahead of the approaching sfc front coupled with a weak mid level shear axis should trigger/sustain scattered convection across our region. May see a few showers over the northern piedmont to start the day. Heating across the east and south sections of our forecast region should destabilize the atmosphere, leading to decent chances for convection by mid-late afternoon. The threat for showers and storms will persist into Sunday night as the sfc front glides southeast across our region. Based on model timing, front should exit the Piedmont counties after midnight, and the southern counties prior today break. A drier more stable air mass will filter into central NC leading to decreasing cloudiness and inhibiting convective development. Surface high pressure will build into our region Tuesday and maintain its position over our area through Thursday. High temps Sunday dependent upon extent of cloudiness/convective coverage. Appears that there will be enough heating in the late morning-afternoon hours to boost temps to near 90-lower 90s. the advection of the cooler air mass will trim max temps 3-4 degrees Monday, and back to near or slightly below normal levels Tuesday through Thursday. High temps generally mid 80s Tue/Wed, and mid/upper 80s thursday. Comfortable overnight temps in the 60s anticipated by Monday night, with low-mid 60s common Tuesday night and Wednesday night. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... As of 635 AM Friday... A weak mid/upper level disturbance moving across the area this morning is supporting some light showers across the northern portions of the area. Brief MVFR conditions may accompany the heaviest showers at KRDU and KRWI through 14Z or so. Otherwise, VFR conditions will continue this morning with a good bid to mid to high level cloud cover traversing the area. Another upper disturbance tracking near the NC-VA border today and a continued hot and unstable airmass will support the potential for scattered showers and storms this afternoon and evening. Any storms that develop will have the potential to produce sub-VFR conditions and gusty winds. Coverage of showers and storms will dwindle with the loss of daytime heating by late evening. However, isolated to locally scattered showers and storms will continue to be possible with a continued threat of mid/upper level disturbances tracking across the area and interacting with a very moist airmass across the area overnight. Looking ahead: Scattered afternoon/evening showers and storm will be possible through the weekend in advance of a cold front passage early Monday. In addition, patchy morning stratus/fog will be possible, especially for locations that receive appreciable afternoon/evening showers/storms. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...BD LONG TERM...WSS AVIATION...BD/BS is the U.S. government's official web portal to all federal, state and local government web resources and services.