Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 101718 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1217 PM EST Sun Dec 10 2017 .SYNOPSIS... A strong upper level trough and accompanying surface cold front will cross the Carolinas early this morning. High pressure will build into the area and extend across the region through Monday. An arctic cold front will drop southeastward through the area early Tuesday, ushering in frigid air for midweek. && .NEAR TERM /today through tonight/... As of 957 AM Sunday... With temperatures currently at or above freezing and on the way up, will let the WSW for black ice expire at 10 AM as originally scheduled. Otherwise, skies have cleared behind the departing trough axis, and we`re in store for ample sunshine today. The morning sounding at GSO shows a well-mixed layer up to about 800 mb that starts just above the shallow sfc-based inversion. Mixing out the aforementioned sfc-based inversion would suggest high temps today from the upper 30s north of the I-85 corridor where there`s snow cover...to lower 40s south of I-85 where there`s no snow cover. Current forecast depicts these conditions, thus no significant changes with the morning update. Previous discussion as of 220 AM Sunday...The influx of colder air with a dry and stable column will ensure a trend to mostly sunny skies areawide by sunrise, holding through the day. Thicknesses are projected to be 40-45 m below normal, indicating chilly highs of 38- 45 despite the abundant sunshine. A fast-moving batch of scattered to briefly broken mid clouds, a product of a strong vorticity lobe passing by just to our north overnight, will bring a period of partly cloudy skies tonight, mainly across the north half. Lows 22- 30. -GIH && .SHORT TERM /Monday through Monday night/... As of 230 AM Sunday... Temps will rebound Mon as surface winds back to southwesterly on the north side of a sprawling surface high spanning the Gulf of Mexico, FL, and off the SE coast. The column will remain dry and very stable aloft with shallow mixing, so still expect below normal highs from the mid 40s N to low 50s SE under mostly sunny skies. Clouds of the mid and high variety will be increasing late Mon through Mon night within an accelerating southwesterly steering flow, with a potent wave dropping SE over the Upper Midwest then E across the Ohio Valley to the N Mid Atlantic states Mon through Mon night, taking another dry cold front southeastward toward our area. Skies should trend to partly cloudy Mon night, with the thickest clouds across the north, and this should temper radiational cooling a bit. Lows 30- 35. -GIH && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 315 AM Sunday... A dry cold front will cross the area on Tuesday which will put a damper on our brief warmup. Highs will reach the upper 40s to low 50s but it isn`t until later in the evening when the colder airmass begins to really filter in. Lows Tuesday night in the low to mid 20s. Continued cold air advection on Wednesday will see highs only reaching the mid 30s to lower 40s as this will be the coldest day of the long term. Lows Wednesday night again in the low to mid 20s. For the end of the week, a warming trend will gradually push high temperatures up to the 50 degree mark across central NC as high pressure builds over the deep south and moves south of the Carolinas and off of the east coast. There is some uncertainty between the GFS and the ECMWF in the handling of a low pressure system that forms in the Gulf of Mexico and moves northeastward over the Carolinas. The current EC scenario has the low well to the east and staying offshore, while the GFS has a much later timing with a westward track that would bring us some precipitation late in the weekend. With uncertainty so high will keep the forecast dry through Saturday. && .AVIATION /18Z Sunday through Friday/... As of 1217 PM Sunday... VFR conditions are expected through the 24 hour TAF period, thanks to mainly clear skies as high pressure builds in from the west. W to NW winds 10+ kts attm will diminish to SW 5kt or less this evening. After 11/18Z: Mainly VFR conditions are expected through the week with high pressure and dry airmass for most of this time period. The exceptions will be associated with cold front passages Tuesday, and another one late Thursday or early Friday. However, right now these systems are expected to pass by without any precip or reduced cig/vsby. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...np/Hartfield SHORT TERM...Hartfield LONG TERM...Ellis AVIATION...np

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