Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 211034 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 630 AM EDT SAT MAY 21 2016 .SYNOPSIS...Low pressure will track northeastward over eastern North Carolina today. An upper level low will drift slowly over the area during the weekend, bringing continued unsettled weather. && .NEAR TERM /today through tonight/...
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As of 630 AM Saturday... The consolidated line of showers (re: 2nd paragraph below) is moving across the i-95 corridor and coastal plain attm as expected. Subsidence behind the causative short wave is eroding the back edge of the showers that are moving across the US-1 corridor. In the wake of the back edge of the current showers, look for a period of little or no shower activity the rest of this morning into mid-day, before scattered showers and tstms become possible again this afternoon and evening. Current forecast is on track, so little or no changes with this update. Prev near term AFD as of 4 AM: Early morning analysis shows a nearly closed mid/upr low moving across the midwest and oh river valley. A short wave out ahead of the closed low is moving across the western carolinas and heading east. A band of mostly-light showers occurring along and ahead of this feature, are currently moving across the western and central Piedmont. Meanwhile at the sfc, high pressure anchored off the New England coast extends wests and southwest with ridging down along the lee of the Appalachians in a CAD pattern. A sfc low along a stationary boundary is located just off the SC coast. For the rest of the early morning period, look for the showers currently moving across the western and central Piedmont to continue to moving east. Meanwhile, an area of rain currently falling across central SC (on the nw periphery of the coastal sfc low) is progged to lift NE into NC and merge with the aforementioned band of showers, generally invof of the i-95 corridor, between 10-13Z. this consolidated band of rain and embedded showers is progged by the latest hrrr to exit east of our CWA between 10-11 AM as the lead shortwave moves east and the coastal sfc low lifts ne across the Outer Banks. Subsidence in the wake of this precip band should facilitate a break in the precip for at least the late morning into the early afternoon. For later this afternoon and this evening, widely scattered showers will move back in and across central NC from the NW and as the next short wave assoc with the closed low moves across our area. While the airmass across the NW Piedmont will not have recovered from the CAD and is expected to remain cooler and stable, a sfc boundary trailing the exiting coastal low is progged to extend across portions of central NC generally along and south of Hwy 64. South of this boundary, the airmass may be warm enough to support isolated thunderstorms, some of which could become marginally strong due to 30-40 kt of 0-6km bulk shear coincident with the area of best CAPE south of the boundary. Right now, SWODY1 shows much of our CWA (mainly south of Hwy 64) in a marginal risk for severe tstms later today, with isolated severe tstm wind gusts the main threat. High temps today will vary from around 70 NW to near 80 SE. Lows tonight in the mid 50 nw to around 60 S/SE.
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&& .SHORT TERM /Sunday and Sunday night/... As of 400 AM Saturday... The risk for scattered showers and isolated thunderstorms will continue through this period as the closed low over PA drifts south across the Mid-Atlantic region and NE NC. POPs during this time will be highest NE in closer proximity to the upper low center, and lowest SW closer to the subsident region of the pattern and subsequent drier airmass. In fact, there`s a good chance that places west and south of a line from Lexington to Fayetteville may remain dry during this time. Temps will continue to run 5-10 deg below normal. Highs Sunday in the lower to mid 70s and lows Sunday night in the lower to mid 50s. && .LONG TERM /Monday through Friday/... As of 300 AM Saturday... Monday and Monday night: An upper level low over NC will gradually shift eastward then northeastward along the Mid-Atlantic coast through Monday night. A slight chance for showers will linger on the back side of the low as it pulls away. The associated surface low will strengthen as it moves north-northeastward along the coast. Surface winds will be mainly NW, shifting to more westerly as the low departs. As a result, expect highs Monday topping out in the mid 70s and overnight lows in the mid 50s. Tuesday through Friday: The upper level low and attendant trough will quickly move away from the area, replaced by ridging aloft. Similarly at the surface, high pressure will build into the region, though central NC will still be on the back side of the departing surface flow Tuesday, resulting in lingering westerly winds. As the low races off to the NE Tuesday night, surface winds will become more southerly. With the surface high and upper level ridge over the region skies will be mostly sunny/clear mid week with moderating temperatures. Weather will remain dry, likely through Wednesday night, with a slight chance for showers and afternoon thunderstorms returning late in the week. Model agreement still is not great at this time so will keep chances limited to slight. Highs in the upper 70s to mid 80s Tuesday will moderate into the mid to upper 80s by Wednesday, where they will remain through the end of the week. Overnight lows will generally be in the mid 60s. && .AVIATION /12Z Saturday through Wednesday/...
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As of 630 AM Saturday... 24 hour TAF period: As of 1030Z...flt conditions from RDU west to INT are beginning to improve as the short wave has passed and the rain has ended. For our remaining TAF sites (RWI and FAY), rain and assoc IFR conditions will remain possible through 12-13Z. Then after 13Z, look for VFR conditions across most of central NC, which will persist through early afternoon. Then later this afternoon and this evening, scattered showers and thunderstorms are expected to re- develop across central NC, resulting in local IFR conditions. More widespread IFR conditions will develop later tonight due to low clouds and some fog, esp invof areas that received heavier rain. Beyond 12z Sunday: the risk for sub-VFR conditions will continue through at least mid-day Monday as a closed low gradually moves south across eastern NC. VFR conditions expected to return by Tuesday and remain for the mid-week period as the closed low moves east and short wave ridging moves over our region.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...RAH NEAR TERM...RAH SHORT TERM...RAH LONG TERM...RAH AVIATION...RAH

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