Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 301044 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 645 AM EDT Mon May 30 2016 .SYNOPSIS...Tropical Depression Bonnie, located over the central South Carolina coast, will drift slowly toward the northeast along the North Carolina coast through mid week, before moving offshore. A cold front will approach from the west late in the week. && .NEAR TERM /Today through Tonight/... As of 255 AM Monday... Mostly cloudy and unsettled weather will persist today with high rain chances, particularly over eastern sections. The center of TD Bonnie, located near CHS early this morning with an inverted trough extending up through the NC Coastal Plain, is still projected to sit and spin in place for much of today, before starting a slow northeastward drift toward the northern SC coast late today through tonight. Its center remains vertically aligned with a baggy upper low along a weak shear axis extending from the OH Valley to the Bahamas, and this stacked troughing with deep southeasterly flow to its NE will keep a moderate flux of both deep moisture (PW of 1.7- 2.0") and mid level vorticity advecting into central and eastern NC today. After a relative lull in precip coverage early this morning, both conventional and convection-allowing models support numerous to widespread showers spreading northeastward into the NC today, with greatest coverage in the northeast CWA where the mid level DPVA will line up with the inverted trough. Will trend pops from low chance early this morning to good chance and likely (highest east half) by afternoon, lasting into the evening before the loss of heating and the slow exit of the shearing vorticity to our NE contribute to diminishing shower coverage. As was the case yesterday, storm coverage and intensity will be limited by marginal instability due to abundant clouds at multiple levels, along with weak bulk shear. Will maintain an isolated storm mention over the eastern CWA this afternoon and early evening. Expect highs from the mid 70s to lower 80s, coolest over the north-central and northeast CWA where sunshine should be minimized. lows in the mid-upper 60s with areas of fog and stratus re-developing tonight. -GIH && .SHORT TERM /Tuesday through Tuesday night/... As of 310 AM Monday... The mid level shear axis will weaken further Tue and continue an eastward drift into eastern NC/SE VA, as the center of TD Bonnie drifts NE over the southeast coast of NC. With the shift of both the mid level shear axis and the inverted surface trough eastward into coastal sections, our rain chances Tue should be a bit lower than today with the best coverage shifting into our far eastern sections and at the coast. PW will remain anomalously high, above 1.5" mainly east of Highway 1, so despite the waning dynamic forcing for ascent, it won`t take much to generate scattered showers and perhaps a storm or two especially over the eastern CWA. Will retain cloudy to mostly cloudy skies east, although the western CWA could see some sunshine if the weak mid level low center shifts into eastern NC/SE VA early enough. Highs in the low-mid 80s, coolest east where clouds should be thickest with greater shower coverage. Lows mostly in the mid 60s. -GIH && .LONG TERM /Wednesday through Sunday/... As of 305 AM Monday... Wednesday and Thursday: Tropical Depression Bonnie will continue to churn off the North Carolina coast on Wednesday somewhere between Wilmington and Cape Lookout. With no steering flow in place the forecast remains status quo with the best chances for precipitation in the east but models also hinting at precipitation forming as the result of orographic uplift as northeasterly flow approaches the Appalachians. Therefore will carry chance of showers and thunderstorms everywhere. Hot and humid with highs in the upper to middle 80s and dewpoints in the mid to upper 60s. Lows Wednesday night in the mid 60s. Thursday will see the depression move a bit further northeast and thus central NC may see a bit of a lull in precipitation before the next system approaches from the west. Will carry low chance pops in the forecast but it is possible that precipitation isn`t realized until later in the day as moisture transport ahead of the front increases. By evening expect thunderstorms to become more numerous in the Triad and points west. These will be driven mostly by diurnal heating as any dynamics associated with the fronts parent low will reside well to the north. Highs still in the mid 80s with lows in the mid to upper 60s. Friday through Sunday: Low pressure moving through the Northern Great Lakes and into Ontario and Quebec will move a frontal zone over the east coast and leave it there as it detaches and heads northeast. Back to the southwest an upper level low developing over Texas will help to initiate the development of a broad upper trough that will drape itself over the eastern US for several days. At the surface a couple of waves, most notably on Saturday afternoon, will move along the front and supply extra forcing for showers and thunderstorms over central NC. Expect best chances in the afternoon each day. Temperatures will cool off some during this time starting in the mid to upper 80s on Friday afternoon down to the lower 80s by Sunday afternoon. Lows each night in the mid to upper 60s. && .AVIATION /12Z Monday through Friday/... As of 645 AM Monday... Periods of adverse aviation conditions are expected to dominate over the next 24 hours at Central NC terminals, as very moist air remains in place over the area. At INT/GSO, MVFR cigs are expected to persist through the morning, before gradually lifting to VFR during the early afternoon hours. Scattered showers this afternoon may generate brief MVFR vsbys here, but otherwise VFR vsbys are expected during the daylight hours today. At RDU/RWI/FAY, IFR/LIFR cigs will persist early this morning, especially at RDU/FAY, where IFR vsbys are also likely. Vsbys at these three sites should improve to VFR later this morning, with cigs slower to improve, trending to MVFR during the afternoon. Isolated showers with MVFR vsbys are likely to pass near RDU/RWI/FAY through mid morning, then coverage will increase by afternoon, with numerous showers and a few thunderstorms this afternoon into evening producing brief MVFR to IFR conditions mainly at RDU/RWI/FAY. Shower/storm coverage is expected to slowly decrease this evening with a trend to MVFR to IFR conditions after sunset. Looking beyond 12Z early Tue morning: MVFR to IFR conditions are likely to hold through mid morning Tue, with improvement to MVFR east and to VFR west during Tue afternoon. Nightfall will bring another trend to sub-VFR conditions at all sites Tue night, as the air mass remains moist and unsettled with the center of TD Bonnie tracking slowly toward the NNE along the NC coast. Improvement to VFR is expected Wed lasting into Thu especially at INT/GSO, as Bonnie moves out over the sea, although sub-VFR vsbys in fog are possible late Wed night into early Thu morning with light surface winds. A cold front approaching from the west Thu night may bring sub-VFR conditions in showers/storms on Fri. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Ellis AVIATION...Hartfield

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