Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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228 FXUS62 KRAH 241840 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 240 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 FRIDAY/... As of 240 PM Friday... A deep low pressure system will lift northeast into the Great Lakes Sunday. Its associated cold front will be weakening and essentially stalling as it edges up against the mountains Sunday and the parent low moves further northeast. This will result in central NC being nicked by only a glancing blow from the stronger dynamic regime associated with the upper system. So, despite our increasingly warm and moist airmass, convection will be favored northwest, with progressively smaller chances heading southeast. Some areas east of I95 may not see any activity at all. Will also maintain small chances for thunder west during the afternoon as instability will be modest and the east will be strongly capped in proximity to the Bermuda high offshore. Highs will reach the low to mid 70s, but the northeast may struggle to reach upper 60s due to heavier cloud coverage and potential shower activity. Warm and moist airmass remains in place in return flow around the Bermuda high with isolated convection on Monday and highs mostly in the upper 70s. A rather weak, but more southerly tracking short wave will be approaching from the west on Tuesday to increase our chance of convection somewhat due to its moving through during the heat of the day. Not seeing forcing that would readily signal potentially strong or well-organized convection, though, so will maintain 40-50 chance PoPs. Tuesdays highs will again climb way up into the 70s, with some lower 80s likely across the southern tier. Highs will again reach upper 70s Wednesday, but only isolated showers look doable in weak westerly low level flow and upper ridging over the area. Cooler high pressure makes a surge down the Atlantic coast on Thursday, with a backdoor cold front threatening to make it as far south as central NC, but low confidence in picking a model solution at this point. We will concurrently have a more southerly low pressure system taking shape over the southern Midwest which would feed moisture into the frontal zone and potentially give us a rain period Thursday night and Friday. && .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...mlm AVIATION...WSS

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