Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 241700 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 100 PM EDT Fri Mar 24 2017 .SYNOPSIS... An area of high pressure anchored offshore will extend west into central NC through Saturday. A weakening upper disturbance will cross our region on Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 1025 AM Friday... An area of high pressure at the surface through 850mb has drifted offshore, resulting in a sw flow in its wake. This flow will advect an increasingly moist and warm air mass into central NC. Aloft, an area of high pressure centered over the northern Gulf will extend newd into the Carolinas. Circulation around this feature will funnel the deeper moisture west- northwest of our region through tonight. The presence of the ridge aloft and the sw flow in the lower levels of the atmosphere will yield partly cloudy skies and noticeably warmer conditions. Afternoon temperatures in the upper 60s-lower 60s will be common. ~WSS 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. ~MWS && .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/... 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. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 100 PM Friday... High pressure at the surface and aloft will gradually weaken and drift east through Saturday night. This will allow an area of low pressure to approach from the west Saturday night and Sunday. The southerly flow ahead of the low will advect a moist air mass into our region, leading to probabilities of MVFR conditions due to low clouds and fog late tonight-early Saturday morning, and again Saturday night into Sunday morning. The sub VFR parameters may linger well into the morning hours before lifting into VFR criteria during the afternoon. The threat for showers appear minimal through Saturday, though the potential appears higher for late Saturday night into Sunday. Periods of MVFR/IFR ceilings and visibility due to fog appear probable Sunday night through Wednesday. The highest threat for scattered showers will be on Tuesday when another upper disturbance passes primarily to our north. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...WSS/MWS SHORT TERM...MWS LONG TERM...Smith AVIATION...WSS

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