Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 231740 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 140 PM EDT FRI SEP 23 2016 .SYNOPSIS... An upper level low and the remnant low from Julia will linger and weaken near the southern Carolina coast through Saturday. A cold front will drop south into the area late Saturday and stall south of the region on Sunday. A stronger cold front will push through the region on Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 145 PM Friday... Quick update to account for a slightly faster erosion of clouds across the northern tier than expected. Mainly clear skies are now noted across Forsyth, Person, Granville, Vance and Warren Counties. Some breaks in the overcast have developed across much of the remainder of the area as well. Isolated to widely scattered showers have developed across the far southern Coastal Plain and Sandhills, these showers will continue to develop and push south during the afternoon. Current PoP and temperature trends looks good and need only minor adjustment. -Blaes Previous discussion from 1045 AM Friday...Latest surface analysis shows a the persistent remnant low from Julia located just south of Cape Fear. A weakening mid level vortex that was located across the eastern Carolinas was beginning to shear out and open up this morning. The air mass across the eastern Carolinas remains very moist with precipitable water values in excess of 1.9 inches in the southern coastal region and Coastal Plain. Notably drier air with PW values of 1.5 inches or less have reached the Richmond Va area and the western Triad. The latest visible satellite imagery shows a large region of almost exclusively low clouds across the eastern two thirds of NC with some breaks and thin spots in the overcast developing. Shower activity to the southeast of I-95 earlier this morning has diminished. NWP guidance is in generally agreement that drier air over VA and northwestern NC will push slowly south into central NC. Should continue to gradually see a lifting of ceilings and brightening of the sky this morning into this afternoon. Expect to see some breaks develop in the overcast, especially in a slightly divergent low level flow to the northwest of interstate 95 with the clouds more stubborn to the southeast of I-95. Convection allowing models develop scattered to widespread convection this afternoon across the coastal region, with more widely scattered convection in the RAH CWA across the southern Coastal Plain and Sandhills region with little chance of rain elsewhere. A weakly unstable air mass with thin CAPE should lead to a few thunderstorms as well, but given the weak flow severe weather is not expected but storms will be capable of producing locally heavy rain as the move slowly. Atypical highs are expected today with the warmest readings in the northwest including the Triad where there will be the most sun with the coolest conditions in the southeast with the more persistent cloud cover and scattered showers. Highs will range from the mid 80s northwest to lower 80s southeast. Skies will continue to clear this evening with the loss of heating and the arrival of drier air. With little forcing for ascent, no rain is expected overnight. Some clouds may persist across the southeast before areas of fog and perhaps some low stratus appear increasingly likely, most widespread from the northern Coastal Plain southwest across the remainder of the Coastal Plain into the Sandhills and eastern Piedmont. Lows tonight will range in the mid 60s northwest to near 780 southeast. -Blaes && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 255 AM Friday... Dry and very warm weather expected. Mid level ridging aloft continues to build in from the west, while at the surface, the weak trough drifts further offshore as weak high pressure moves in from the west, although lee troughing does form in the afternoon over the western Piedmont. With low PW and a fairly stable column, will keep pops under 15%, with mostly sunny skies. Thicknesses and statistical guidance indicate highs in the mid-upper 80s, around 6-10 degrees above normal. The anticipated backdoor front moving toward NC from the NNE is poised to move into the NE CWA Sat night into early Sun morning, driven by energy rotating around a large vortex centered near the Newfoundland/Quebec border. But this low does not appear to dig markedly down the East Coast, hinting that the front may not work very far into NC despite being propelled by a cool dense surface high to our north. The ECMWF tends to hold the front just north of the VA/NC border through daybreak Sunday, while the NAM/GFS dip the front into northern NC. Will lean toward the ECMWF solution and hold onto mild temps overnight, with lows Sat night in the mid- upper 60s and a minimal drop in dewpoints over the NE. Regardless of frontal progression, we are likely to see increasing clouds from NNE to SSW Sat night. While a few models generate shower activity ahead of or along the front over north central and NE NC Sat night, the presence of features to force ascent is uncertain, and will opt for dry weather for now and monitor trends. -GIH && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 320 AM Friday... Confidence in the long term forecast is still fairly low but nothing like it was yesterday morning as model solutions are slowly starting to come up with somewhat of a common solution. The big difference maker, which was the blocking pattern in the GFS solution is not showing up as much as in previous runs and has allowed high pressure over to come southward out of Quebec on Sunday to become more transitory and move into New England on Monday and out to sea on Tuesday. This allows a cold front to drop into the Carolinas on Wednesday, hang up over the area on Thursday before exiting to the south Thursday night into Friday. During this time period the best chances for thunderstorms would be on Tuesday and Wednesday ahead of and with the cold front. Otherwise some slight chances for rain throughout the period, mostly in the form of diurnal showers are possible. Temperatures will generally stay in the upper 70s to low 80s before the cold front with some hints at some highs in the mid 70s for the end of the week. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 650 AM Friday... Widespread IFR to LIFR conditions will linger through 12-13z this morning across all of central NC, a result of light winds along with stable and very moist air in the low levels. Cigs are expected to rise to MVFR between 14z and 16z, and then to VFR between 16z and 18z west (INT/GSO), 18z-20z central (RDU), and 19z-21z east (RWI/FAY). Rain chances today are low west (INT/GSO) trending higher east (RDU and especially RWI/FAY), with the highest coverage near FAY, which could see a few hours of showers, and perhaps a storm or two, with MVFR vsbys and cigs this afternoon. Conditions will trend toward VFR everywhere after sunset tonight, as weak high pressure starts to build in from the west with drier air moving in. Looking beyond 12z Sat morning, VFR conditions will dominate into Sat evening, with the risk of sub-VFR stratus and fog returning late Sat night/Sun morning as a backdoor front approaches from the north. MVFR cigs may linger through much of Sunday and Sunday night, although confidence is not high, as there is uncertainty regarding the southward pace of the backdoor front through NC. After mostly dry weather Sat, the chance for sub-VFR showers and storms returns for Sunday along the backdoor front. Shower/storm chances will increase further late Mon into Tue as an upper level low pressure trough approaches from the NW. There may be a risk for low level wind shear early Tue morning. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES/HARTFIELD SHORT TERM...HARTFIELD LONG TERM...RE AVIATION...HARTFIELD

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