Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 150138 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 940 PM EDT Wed Mar 14 2018 .SYNOPSIS... High pressure will drift across the Gulf Coast states and Southeast states through Thursday. A backdoor cold front will drop southward into the area Thursday night, before stalling across the Carolinas on Friday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 940 PM Wednesday... A deep l/w trough over the eastern U.S. with a series of perturbations aloft will maintain a chilly air mass across central NC tonight. As the perturbations drop into the base of the l/w trough, moisture associated with the disturbance will skirt across central NC, resulting in periods of partly cloudy skies, primarily across the northern counties. The low level cold air advection will continue as the 850mb temperature trough is centered to our northwest. Min temperatures in the mid-upper 20s appear on target. Wind chill values by early Thu will be close to 20 degrees across the NW Piedmont.
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As of 940 PM Wednesday... The l/w trough will undergo a brief period of amplification/digging Thu as as/w digs sewd into the base of the trough. This will enhance the wly flow over our region, leading to the development of a lee side/Piedmont trough. The deep low to the north of New England and a sfc high over the Deep South will maintain the gusty winds over our region, enhanced by the mid level winds of 60-70kts, and 850mb winds of 35-40kts. Wind gusts Thu afternoon of 30-35 mph expected. Meanwhile the air mass will continue to be rather dry with sfc dewpoints in the lower 20s. These dewpoints coupled with afternoon temperatures in the 60-65 degree range will yield relative humidity values between 20-25 percent.The low RH and the strong gusty winds will create conditions that may lead to adverse fire behavior. Thus, will issue a SPS highlighting these conditions, and discourage outdoor burning. A backdoor cold front associated with the s/w will drop into central NC Thu night. Not much weather expected to occur with the front aside from patchy cloudiness. The clouds coupled with a modifying air mass will yield overnight temperatures that should vary from the 30s to around 40 north, and 40-45 degrees south.
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&& .LONG TERM /FRIDAY 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 /00Z THURSDAY THROUGH TUESDAY/... As of 735 PM Wednesday... 24-Hour TAF Period: Confidence remains high that VFR parameters will prevail through the TAF Period. SCT/FEW CIGS will give way to clearing skies overnight across central NC, with only maybe a few waves of upper-level cirrus passing overhead. Winds will diminish after sunset, with gusts subsiding to light westerly/northwesterly flow between 4 and 8kts at the surface. Winds will pick up again mid morning, and shift slightly southwesterly as a high pressure pivots across the FL peninsula and a shortwave pushes through from the North. Expect sustained winds in the teens, with gusts as high as 20 to 30kts, especially after the noon hour. Possibly a few LLWS concerns Thursday evening around dusk, especially out east at KFAY/KRWI, but have left these out of this TAF issuance as confidence on timing and location remains low. -JJM Looking ahead: VFR conditions are expected to hold true through late in the work week as high pressure drifts over the Southeastern U.S. states. A backdoor front will approach from the north late Thu before pushing southward through NC Thu night. This may bring a period of sub-VFR conditions with rain chances Sat into Sun as the front stalls out over the Carolinas, with a series of upper level disturbances tracking over the region along the surface frontal zone. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...KC NEAR TERM...WSS SHORT TERM...WSS LONG TERM...mlm AVIATION...JJM/Hartfield is the U.S. government's official web portal to all federal, state and local government web resources and services.