Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 150631 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 230 AM EDT Thu Mar 15 2018 .SYNOPSIS... High pressure will remain centered to our south, crossing Florida today before moving off the Florida coast tonight. A backdoor front will push southward into the area late tonight before stalling across the Carolinas Friday into Saturday. && .NEAR TERM /TODAY THROUGH TONIGHT/...
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As of 205 AM Thursday... Quiet but windy day. As the surface high center holds to our south, drifting to the ESE, the approaching backdoor front will tighten the pressure gradient, while very deep mixing taps into strong winds aloft. Models depict a 50+ kt 850 mb jet from central IL into the southern Appalachians this morning, and as this sweeps across the area today, we should easily be able to tap into these winds. Gusts of 30-35 mph should be common, mainly in the mid to late afternoon, with sustained speeds of 15-25 mph. These values are below wind advisory criteria, so will stick with a mention in the hazardous weather outlook, but this situation will be monitored closely today. (See fire weather discussion below.) Otherwise, a batch of moisture around 850-700 mb will cross NE NC this afternoon, so expect a period of broken clouds there, with just scattered high-based flat cu elsewhere, at most. As we mix up into rapidly warming air aloft, temps should top out close to seasonal normals, 60-66. Winds should diminish tonight to under 12 mph after nightfall as we decouple with decreasing winds aloft. Expect fair to partly cloudy (NE) skies as we continue to see a streak of 850 mb moisture across N and NE sections overnight, as the backdoor front drops into far N and NE sections of NC. Lows 36-44. -GIH
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As of 230 AM Wednesday... The backdoor front will continue to settle to the SSW, likely stretching across southern NC Fri into Fri night. Expect some clouds near the frontal zone Fri, but the more marked increase will come late Fri through Fri night as the mid level flow flattens and small perturbations track ESE into the Carolinas. A shortwave trough will cross the Midwest and into the NW Ohio Valley through Fri night, accompanied by a surface low along the frontal zone, to a position near St. Louis by Sat morning. Forcing for ascent appears minimal until late Fri night, when a strengthening upper jet from AR southeast through GA induces increasing upper divergence moving into W NC, along with the weak but improving DPVA and arrival of a southwesterly 40-50 kt 850 mb jetlet nosing into W NC. Will gradually bring low pops into the far W CWA late Fri night, along with increasing clouds. Will have highs from the upper 50s NE to near 70 SW Fri, with the front bisecting the area. Lows 33 to 43, again NE to SW, Fri night. -GIH
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 250 PM Wednesday... A nearly stationary frontal zone will develop between high pressure edging off the southeast coast and high pressure over the Great Lakes trying to edge south and down the coast. This front will be across the area on Friday, with cooler highs in the upper 50s north to potentially 70 degrees across the southern tier counties. A mid level short wave will be moving southeast, nearly paralleling to the frontal zone, increasing cloud coverage and chances for showers, mainly in the western Piedmont, Friday night. Lows will be range widely, from low and mid 30s north to lower 40s south. The forecast becomes a bit messier through the weekend due to split, near-zonal flow aloft. A weak cold front will be pushed rapidly east, then southeast over the weekend as the flow begins amplify, ridging north into the Midwest Sunday. The front will be accompanied by a chance of showers, mainly through Saturday afternoon, and highs will be seasonable, mid to upper 50s. Sunday looks to be dry and a bit warmer, 60 to 65, as heights build with the ridging aloft. For early next week, another strong low pressure system will track across the Ohio Valley, with patchy to widespread rain developing ahead of the low due to modest isentropic lift Monday into Monday night. As the low deepens and moves offshore, expect wrap around rain showers on Tuesday, and there is a chance that we could see enough cold air advection to cause a brief mix with snow across the northern tier before the precip ends late Tuesday. Highs Monday and Tuesday are a challenge at this point, and a wide north-south variation is possible, due to uncertainty as to the degree of evaporative cooling/in-situ damming effects. Regardless, highs across the north should reach at least mid and upper 50s, with lows across the south in the low to mid 60s. Morning lows will be in the low to mid 40s both days. Sunny skies are expected Wednesday in northerly dry and cool air advection. Highs will be in the mid and upper 50s. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... As of 150 AM Thursday... VFR conditions are likely to persist through the next 24 hours, although the winds today may be problematic for aviators. High pressure remains centered to our south today/tonight, as a backdoor front approaches from the north. The tightening pressure gradient will lead to strong surface winds from the SW and WSW today, sustained at 15-20 kts with frequent gusts around 30 kts. Mechanical turbulence may be generated. The strongest winds are most likely to occur between 2 pm and 6 pm. After sunset, winds aloft remain strong (25-40 kts, strongest across the SE, at around 2k ft AGL) despite decreasing to around 10 kts at the surface, so low level wind shear may impact FAY after 00z. Any clouds this afternoon will be VFR and mainly affecting RDU/RWI. Looking beyond 06z Fri, VFR conditions will hold through Fri as the backdoor front drops into the area and stalls across the Carolinas. Upper level disturbances tracking ESE across the area (along the frontal zone) will bring increasing chances for sub-VFR conditions Sat/Sat night. VFR conditions may return briefly Sun, then another threat of sub-VFR conditions is possible on Monday. Confidence is not high during the Sat-Mon time frame, with wide variation among models regarding timing of these disturbances, so aviation interests should check back for the latest. -GIH && .FIRE WEATHER... Relative humidity is expected to bottom out between 19% (south) and 27% (north) this afternoon, while surface winds increase to sustained speeds of 15-25 mph, with frequent gusts to 30-35 mph, from the SW and WSW. This combination of low RH and strong winds may lead to adverse fire behavior today. An SPS to cover the increased fire danger ill be continued. Given these meteorological conditions, a dditional coordination with forestry officials will be conducted this morning to determine if fuel moisture levels warrant a red flag warning today. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...mlm AVIATION...Hartfield is the U.S. government's official web portal to all federal, state and local government web resources and services.