Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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969 FXUS62 KRAH 240806 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 405 AM EDT Fri Mar 24 2017 .SYNOPSIS... A warm front will lift north across NC and VA today. Bermuda high pressure will then extend across our region through early next week, though interrupted briefly by the passage of a shortwave trough on Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 345 AM Friday... 1036 mb high pressure now centered a few hundred miles east of the DelMarVA will drift to near and just north of Bermuda today. Return Sly flow around the wrn periphery of the ridge will cause warmer and more moist air to flood north through the Carolinas and VA today, with afternoon temperatures in the upper 60s NW to lower 70s elsewhere in central NC, and surface dewpoints rising into the 40s to near 50 degrees. The increasing low level moisture values, and broad WAA regime, will favor a scattering of flat/fair weather cumulus trapped beneath a subsidence inversion that will have become established courtesy of an amplified longwave ridge now building east toward the Appalachians. Not as cool tonight, and with a chance of patchy radiation fog owing to the aforementioned increase in low level moisture values, with low temperatures mostly in the upper 40s (45-50) expected. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 355 AM Friday... A mid-upper level trough axis extending south from a closed low now over sern CO will migrate newd from the MS Valley early Sat to near the srn Appalachians by Sun morning, as the parent upper low lifts toward the Great Lakes. Associated mid level height falls on the order of 20-30 meters will pivot NEwd across central and wrn NC Sat and Sat night, but lingering influence of the preceding ridge axis aloft/sub-tropical ridge will maintain a strong capping inversion and dry air aloft. As such, precipitation chances will remain low through Sat night, with perhaps just a slight chance of a shower near the Yadkin River by 12Z Sun. Even then and there, however, instability will be weak, shallow, and still capped by the inversion, so the (relatively) better chances of any showers will not occur until Sunday. It will otherwise be warm Sat, with scattered to broken fair weather cumulus, and mild Sat night with both thickening high level cloudiness in Swly flow aloft, and a chance of stratus over the wrn piedmont late. Highs in the lower to middle 70s, and lows in the lower to middle 50s. && .LONG TERM /Sunday through Thursday/...
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As of 400 AM Friday... An upper low will lift from the southern Plains to the Great Lakes this weekend, with its associated cold front and convection moving across the deep South on Saturday and Saturday night. As the upper low lifts and weakens, the cold front essentially stalls well west of the mountains and leaves NC int he warm sector through the middle of next week. Despite the lifting upper low taking on a negative tilt Sunday, only a glancing shot of 40-60m height falls over the western piedmont and generally weakening deep layer forcing should cause the convection to weaken as it moves into the southern Appalachians early Sunday. South-southeasterly low-level flow may sustain showers and isolated storms over the western Piedmont on Sunday, while areas of east of US 1 may see no precip at all. Instability will be hampered in the west by early morning clouds and scattered showers, while a dry mid-level cap will be more pronounced to the east where a ridge of high pressure off the coast has more influence. Expect highs to range from around 70 west to near 80 east. High pressure will continue to influence the region early next week, with warm return flow around the high and thicknesses approaching 1400m by Tuesday. Showers and storms will be possible Tuesday as another shortwave lifting out of the southwest US moves east across the Mid-South. models continue to struggle with the amplitude of this yet to be well sampled wave, and thus confidence in the coverage of convection is low. However, strong diurnal heating and modest dewpoint recovery through early next week suggests some strong storms could be possible if the wave and associated shear are strong enough. Highs should easily be in the mid 70s to low 80s Monday, Tuesday and even Wednesday, before a back door cold front is forecast to slip into the area by Thursday.
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&& .AVIATION /06Z FRIDAY THROUGH TUESDAY/... As of 220 AM Friday... A lingering continental (dry) air mass, deposited by strong high pressure now drifting off the NC/VA coast, will result in continued VFR conditions through the TAF period. Surface winds, in return flow around the surface high, will become Sly to SSWly and increase into the 8-13 kt range, strongest and with at least occasional gusts into the upper teens kts at nrn TAF sites. A warm front and influx of low level moisture will result in the development of a scattering of flat cumulus, with bases around 4 k ft, today. Outlook: Patchy MVFR-IFR visibility restrictions in radiation fog will be possible early Sat morning. Associated moisture may then produce a few hour period of scattered to broken MVFR range cumulus with diurnal heating mid-morning to midday Sat, especially at Piedmont sites. Late night-early morning fog and/or stratus, then MVFR range cloudiness as that moist layer is heated through midday each day, will be possible through early next week. Otherwise, a chance of showers and storms and sub-VFR conditions mainly at Piedmont TAF sites will exist Sun, then again forecast area-wide on Tue. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...MWS LONG TERM...Smith AVIATION...MWS

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