Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 261855 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 255 PM EDT WED OCT 26 2016 .SYNOPSIS... Cool high pressure will extend into our region from the north through tonight, before shifting offshore early Thursday. A cold front will move into the area from the northwest Thursday night. && .NEAR TERM /through tonight/...
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As of 230 PM Wednesday... Quiet weather and generally clear skies for the rest of the afternoon will give way to increasing clouds overnight, as the surface ridge axis extending into the area from the north shifts east and offshore, resulting in a low level return flow and inducing strengthening and deepening moist isentropic upglide focused at 285- 295K, within a surface-based stable layer extending up to around 940 mb. This should lead to development of stratus late tonight as the upglide ramps up. We`ll also see increasing mid and high clouds based around 18kft to 25kft, ahead of the weakening positively tilted mid level shortwave trough, spreading in from the west soon after midnight, and this in part may help limit fog development, and as such, stratus is favored as 925-850 mb flow increases late from the southwest. All of this will translate to clear skies this evening, trending to mostly cloudy or cloudy overnight. Expect lows to be much milder than last night, in the mid-upper 40s. -GIH
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&& .SHORT TERM /Thursday through Friday night/...
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As of 250 PM Wednesday... We`re firmly in the warm sector for the entirety of Thu, although the chance for any significant precip late Thu into Thu night remains on the low side. Vorticity within the incoming weakening mid level shortwave trough continues to shear out as the trough axis swings through the area Thu, just ahead of the weak surface front being driven by potent surface and mid level low pressure crossing the Great Lakes and Northeast. Forecast soundings indicate a dry and fairly stable column between 850 and 700 mb, coupled with borderline surface dewpoints low to rise into the 50s until late in the day. By the time the lower levels moisten up, the mid levels (500-700 mb) begin to warm and stabilize/dry out Thu night as the weak trough axis shifts to our east. This all serves to limit deep destabilization that would support convection ahead of or with the front. Other forcing mechanisms also grow weaker with each model run, it seems, with upper divergence a non-issue at our latitude based on weak upper winds, and an 850 mb southwesterly jet that is focused well to our northwest and north. Ensemble model output shows unimpressive precip chances, with the SREF probabilities of measurable rain quite low, even in our far northern section, while the GEFS members almost uniformly indicate just a few hundredths of an inch of precip through the event. Will trim pops by a few percentage points, keeping chances in the far north and northeast with no better than a slight chance of showers along and south of Highway 64 through central NC, focused on very late Thu afternoon into Thu evening. The trough axis hangs back just enough to keep a few clouds in central and eastern sections later Thu night, but these should clear out for Fri, yielding mostly sunny/clear skies Fri/Fri night as broad mid level ridging extending from west of Baja California NE through the lower Miss Valley builds toward the Carolinas. Models don`t show much of a dropoff in thicknesses heading into Fri, mainly because the surface front will be undergoing frontolysis by that point as it dips into northern NC Fri morning before washing out completely. Expect highs of 72-77 Thu and 69-76 Fri. Warm lows in the 50s Thu night and in the upper 40s to lower 50s Fri night. -GIH
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&& .LONG TERM /Friday through Tuesday/... As of 304 AM Wednesday... Cold front will be near the NC coast by 12z Friday. Lack of CAA will result in high temperatures on Friday similar to those on Thursday. Transitory surface high pressure will build across the area in the wake of the front Friday, before shifting south of the area Saturday. Another cold front will move quickly through the region Sunday. Dry westerly flow aloft with little moisture return will result in a dry passage, followed by weak surface high pressure and upper level ridging Monday and Tuesday. Temperatures will remain above normal through the period, with highs in the 70s. && .AVIATION /18Z Wednesday through Monday/... As of 1205 PM Wednesday... Confidence is high that we`ll see VFR conditions continuing through this evening, with high pressure nosing into the region from the north and warm/stable air aloft. However, conditions are expected to deteriorate overnight, starting after 06z in the southeast (FAY) and after 08z elsewhere, as low level return flow brings increasing moisture into the low level (under 3 000 ft AGL) surface-based stable layer. A trend to MVFR or IFR cigs is likely late, lasting through 13z, followed by a trend to low-end VFR through 16z, with gusty winds from the southwest developing at all sites. Patchy sprinkles are possible toward the end of the TAF valid period at INT/GSO/RDU, but any sprinkles will be isolated and not impactful to aviation interests. Looking beyond 18z Thu, a few showers with MVFR conditions are possible in the west (INT/GSO) in the 21z Thu to 03z Fri time frame, and in the 00z to 06z Fri time frame elsewhere (perhaps lasting until 09z at FAY/RWI), but VFR conditions should remain dominant with any sub-VFR conditions being very brief with only light precip expected. Sub-VFR shallow ground fog is then possible late Thu night into Fri morning (mainly 08z-13z). A weak cold front will drop southward into the area Fri morning, with high pressure building in behind it from the north. VFR conditions will return by mid morning Fri, holding through the weekend and into early next week, although sub-VFR fog/stratus is again possible early Sat morning and again Mon morning as the high shifts to our southeast and another mostly dry front approaches from the north. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...30 AVIATION...Hartfield is the U.S. government's official web portal to all federal, state and local government web resources and services.