Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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702 FXUS62 KRAH 030045 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 845 PM EDT Thu May 2 2024 .SYNOPSIS... A backdoor cold front will approach the area from the northeast on Friday before stalling over the northern Coastal Plain by Saturday morning. A series of weak upper level disturbances will move through the region Friday evening through Sunday, bringing periods of unsettled weather. && .NEAR TERM /THROUGH TONIGHT/... As of 845 PM Thursday... Little change to the going forecast for the rest of tonight. The Mid- level ridge will remain anchored in place, although some energy from the Mid-Mississippi valley and OH valley will reach portions of eastern TN, increasing some high clouds toward daybreak. The main forecast challenge will be if we see fog like we did yesterday, and if so, where. Dewpoints mixed out into the low to mid 50s in most places, indicating the dry air in place. However, observations and model forecasts indicate these dewpoints rising into the low to mid 60s overnight with the inland sea-breeze. Dewpoints are already in the mid 60s over some parts of the southern Coastal Plain. So there could be some potential for some shallow fog beneath the drier air and inversion that develops. However, most guidance keeps the best chance over far SE NC. The best chance appears over the eastern Sandhills to southern Coastal Plain, where dewpoints are expected to be higher. Lows were raised a degree or two given the expected weak moist advection. Lows to range from 57 to 64. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 230 PM Thursday... A convectively enhanced disturbance over the Ohio Valley Fri morning will largely remain to our west and north as it rides through the western periphery of the high amplitude ridging along the East Coast through the Great Lakes. At the surface, a lobe a high pressure will ridge south through the Northeast and down the Mid-Atlantic coast during the daylight hours. This should effectively push a shallow backdoor cold front combined with the seabreeze through southeastern VA into the northern Coastal Plain of central NC Fri evening before stalling overnight. 12z Hi-Res guidance hints at some isolated shower potential early Fri afternoon over the Piedmont, but limited instability, dry air aloft, and a deeply mixed boundary layer will likely prevent much outside of towering cumulus and an isolated shower. Otherwise, a very similar airmass will be in place with marginally cooler 850mb temperatures compared to Thurs and would result in highs in the upper 80s to around 90. Thickening mid/high clouds and bubbling cumulus during the afternoon may keep temperatures in the Triad closer to low/mid 80s. Underneath a blanket of cloud cover overnight, lows will be more uniform across the area with lows in the low/mid 60s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 220 PM Thursday... The first half of the extended forecast will feature an unsettled pattern. A weak surface low will be over the Ohio River Valley Saturday morning, slowly move to the east over Virginia by Sunday morning, then dissipate. A cold front will extend to the south from the low, and the front will be the primary rain-maker over the weekend. Extended likely pops a bit farther to the east both Saturday and Sunday. Rainfall amounts will range from a quarter inch in the southeast to nearly an inch in the northwest - needed rainfall, but not enough to change the drought status (almost all of which is D0 - abnormally dry - in our area). All locations will have at least a slight chance of thunderstorms, although instability values will be a little higher in the west. After the upper 80s and lower 90s of today and tomorrow, highs will be more seasonable for the weekend, ranging from the upper 70s the mid 80s. An upper level trough will approach the area Monday and move overhead Tuesday, bringing a chance of showers and thunderstorms to all locations. The forecast should then generally dry out for the middle of the week. However, an upper ridge will build across the Carolinas, and with southwesterly surface flow, temperatures will rise above normal again. By Wednesday and Thursday, highs should be in the lower 90s with lows around 70, values more typical of July and August than early May. && .AVIATION /00Z FRIDAY THROUGH WEDNESDAY/... As of 715 PM Thursday... Generally VFR conditions are forecast under high pressure through 18z/Friday. Looking beyond 18z Fri, VFR conditions are likely to hold through Fri, although mid/high clouds will gradually increase from the west. The chance for sub-VFR conditions within scattered to numerous showers and storms will increase starting late Fri night, lasting through Mon, as a series of disturbances passes over the region. Areas of early-morning fog are also expected. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Swiggett/Hartfield NEAR TERM...Kren SHORT TERM...Swiggett LONG TERM...Green AVIATION...pwb/Hartfield