Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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020 FXUS62 KRAH 041908 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 308 PM EDT Tue Jun 4 2024 .SYNOPSIS... A series of mid-level disturbances will move east and interact with an unseasonably moist airmass over NC through Thursday. A pre- frontal trough and cold front will move across the area Thursday evening through early Friday. && .NEAR TERM /THROUGH TONIGHT/... As of 300 PM EDT Tuesday... A shortwave trough centered over the western NC this afternoon is expected to continue eastward through the afternoon and evening. As surface high pressure off the Mid-Atlantic coast continue to pump warm moist air into the region showers and storms will continue to develop over the next few hours. Expect storms to be pulse-type especially over the NW Piedmont region as the shortwave trough moves closer to the region. A second round is possible later tonight as an approaching MCV from the SW could re-develops closer to the region. While coverage is isolated this afternoon and evening, PoP chances slowly reduce, not completely diminish overnight into early Wednesday. WPC has maintained a marginal ERO for excessive rainfall across the much of the area with the greatest threat for flash flooding in urban/flood-prone areas. Lows overnight will range from mid to upper 60s. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... As of 225 PM Tuesday... Upstream MCVs will continue to influence central NC`s sensible weather during this period as Bermuda high pressure remains in control. The first MCV, currently over central TN, will likely traverse central NC during the 1st half of the diurnal cycle. Isolated to widely scattered weak convection is possible as this feature moves through the area during what is otherwise poor diurnal timing. In the wake of the lead MCV, possible remnants of another MCV associated with the linear cluster over NE TX and lower MS Valley, could potentially move through the area during peak afternoon heating, with re-development of showers and storms from west to east across the area during the afternoon and evening. Deep layer shear increases slightly, but is still weak, and should mitigate the severe threat. Mean storm motion should also be higher than recent days, but given moist PWATs of 1.9-2.0", some localized flash flooding remains possible. Isolated to widely scattered showers/storms could linger overnight, especially with renewed lift from an elongated shortwave trough extending south from the mid- latitude cyclone over southern Ontario. Highs into the mid 80s to around 90 F, with some lower 80s possible over the NW Piedmont where the second round of convection could pop off earlier. Lows in the mid 60s to lower 70s with areas of stratus expected. && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 305 PM Tuesday... An oblong upper low will be positioned from Manitoba through southern Ontario and Upper Great Lakes Thurs morning with an occluded surface low stacked underneath over Ontario. Enhanced southwesterly flow centered around 850mb will overspread central NC through the early morning into the evening hours with boundary layer mixing supporting 20-30 mph wind gusts, highest in the Coastal Plain into the Sandhills. A weakening ribbon of vorticity is forecast to spread from the southern Appalachians Thur morning through the Coastal Plain by the evening hours. This band is expected to produce a narrow band of showers/storms traversing across the forecast area with a deepening trend as it overlaps with better pool of instability over the Coastal Plain into the Sandhills. Despite increased flow around 850mb, flow aloft is rather weak with central NC displaced southeast of the better dynamics aloft. This will result in relatively weak deep layer shear with a majority of the speed shear confined to the lowest 3km. This may result in loosely organized clusters tracking along the lead cold front. Severe threat predictability is low at this time, but sub-severe wind gusts and small hail in the deepest updrafts certainly seem possible through the early evening hours. A reinforcing cold front will move through Thurs night into Fri morning and will bring in drier air with dew points falling to the 50s by Fri afternoon. Deep layer moisture will dry out with PWATs falling to around 0.8 inches (approaching the 10th percentile for GSO) and will lead to a dry and more comfortable forecast for Fri through Sun. Steady moisture advection from the west and southwest with periods of troughing over the eastern CONUS will bring back mostly diurnal chances for showers/storms for early next week. Behind the cold front, temperatures will generally waver around near- normal values. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... As of 205 PM Tuesday... Isolated showers and storms are beginning to develop across portions of the CWA, but ceilings are generally around 3k-4k ft over the Triad and 4k-7k elsewhere. Mostly VFR conditions are expected this afternoon and evening with the exception of periods when storms move over/near the terminals causing reduced vsby and ceilings. As the mid level disturbance moves across the region tonight and early morning, this could result in some flight restrictions early Wednesday morning ahead of the cold front. Outlook: Showers ans storms associated with a cold front that is expected to come through the region late Wednesday /Thursday will result in flight restrictions of MVFR or lower in some areas. VFR conditions are expected to return Friday through the weekend before another disturbance moves into the region early next week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...CA SHORT TERM...CBL LONG TERM...Swiggett AVIATION...CA