Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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929 FXUS62 KRAH 152332 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 632 PM EST Wed Nov 15 2017 .SYNOPSIS... High pressure over the middle Atlantic states will weaken and shift east early tonight. A weak upper level trough will move across NC tonight, with the surface high pressure to follow Thursday night into Friday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 630 PM EST Wednesday... Mid and upper level cloud cover will continue to thicken this evening in advance of the northern stream trough currently moving through the Great Lakes. Otherwise, only minor/cosmetic updates were made to forecast grids. Previous discussion from 330 pm ... Just a couple of minor issues to deal with tonight. First, the stratocumulus seen along the SE Coastal Plain moving NNW from offshore of Wilmington. This cloudiness was associated with low level moisture return, along the periphery of the departing surface high, seen shifting off the coast in the latest data. These clouds are expected to affect areas along and east of Interstate 95 through the early evening, bringing mostly cloudy skies there. Elsewhere, only scattered to broken cirrus and cirrostratus were spreading eastward across the region. This leads to the other minor issue of the approaching but weakening mid/upper trough from the WNW. Since this feature is expected to become moisture starved as it pushes over the Appalachians tonight, we will exclude POP for the night. However, mid and high cloudiness will increase, and this may play a role in warmer lows overnight, especially in the west and north where clouds will be thicker. It does appear that it will clear between 06z-09z in the NW, with clouds lingering down east through around daybreak. We will raise lows a degree or two and go with the warmest MOS lows overnight ranging in the upper 30s to lower 40s all zones. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... As of 330 PM Wednesday... A secondary cold front is expected to push through late Thursday. Until then, drier and sinking air will follow the departing mid/upper trough Thursday. Temperatures should warm well into the 60s (near 70 Sandhills) with WSW flow at 10-15 mph. Winds will die off overnight Thursday, with clear skies as the high pressure builds overnight. Lows generally in the mid to upper 30s expected, with lower 30s in the normally colder locations of the Piedmont. The high will be overhead Friday into Friday night supplying clear skies and light winds. Highs 55-62. Lows Friday night will depend on the timing of WAA, much of which will likely be felt aloft and not at the surface. This may be especially in the east, where the ridge will be slower to depart. Lows should be coolest in the NE - warmest SW (35-42). && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 340 PM Wednesday... Shortwave ridging aloft across the mid-Atlantic early on Saturday pushes offshore as a progressive upper-level trough moves across the OH and TN Valleys Saturday afternoon an then pushes off the east coast Sunday night. The associated cold front will reach the southern Appalachians Saturday evening and then reach the coast around Sunday morning. Vigorous low-level flow with southwesterly 850 hPa winds of 40-50 kts are expected ahead of the front while stout southwesterly winds of 130+ kts are expected at jet level. Even with these dynamics, the best forcing for ascent lifts northeast away from the Carolinas which combined with limited moisture return and a progressive pattern will result in a brief and generally light precipitation event with precipitation amounts of a tenth or two. The weather pattern quiets and chills with generally fair weather expected for Sunday into early next week as deep troughing across develops across the eastern CONUS on Sunday and Monday. The is followed by a period of short-wave ridging late Monday into early Tuesday. The southern jet stream becomes more active across the Deep South and Gulf Coast into Wednesday as troughing develops in the vicinity of the lower Mississippi Valley. Not much confidence in forecast details late Tuesday into Wednesday as this pattern can be difficult to forecast, especially at day 7 but fair and dry weather still expected. With a strong southerly flow and a delayed arrival of clouds and precipitation, raised max temperatures on Saturday to the mid 60s to lower 70s. Temperatures cool on Sunday with highs in the lower to mid 50s and cool even further on Monday with highs only in the upper 40s to lower 50s despite lots of sunshine. A moderation to just below normal temperatures are expected on Tuesday and wednesday with highs in the mid 50s to around 60. -Blaes && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 630 PM Wednesday... Band of weak showers accompanying associated with the northern stream through and attendant cold front moving through the region overnight/early Thursday morning will largely dissipate east of mountains overnight, hindered by dry air in the low-levels. Thus, dry VFR conditions will persist with only a 4 to 6 hour period of broken/overcast of VFR ceilings with cloud bases between 8 to 10kft expected. Subsidence in the wake of the upper level trough will lead to abrupt west-east clearing Thursday morning. Light and variable this evening will become westerly overnight and then NWLY on Thursday behind the sfc cold front. Outlook: Generally VFR conditions expected until the next cold front that is forecast to arrive Saturday night. This may result in MVFR to IFR CIGS and MVFR VSBYS for a period Saturday night and early Sunday. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...BADGETT NEAR TERM...CBL/BADGETT SHORT TERM...BADGETT LONG TERM...BLAES AVIATION...CBL/BADGETT

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