Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 141049 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 650 AM EDT Wed Mar 14 2018 .SYNOPSIS... A strong mid and upper level disturbance will move over North Carolina this morning, bringing a surface trough southeastward through the region. High pressure will drift across the Gulf Coast states and Southeast states this afternoon through Thursday. A backdoor cold front will drop southward into the area Thursday night, before stalling across the Carolinas on Friday. && .NEAR TERM /TODAY THROUGH TONIGHT/...
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As of 650 AM Wednesday... A cluster of dynamically-driven snow showers has survived the trip over the higher terrain intact, and is now moving toward the SW Piedmont. With the increasing chance that at least southern portions of the CWA could see a few flurries or snow showers despite the high dewpoint depression, have nudged pops up slightly and increased the area that could see flurries over the next few hours. -GIH Previous discussion from 245 am: Weak elevated returns persist over the SE half of the forecast area, along a weak surface trough and just ahead of a 700 mb trough, although the relative dry low levels are keeping much of this from reaching the ground so far. A strong mid level vort max seen on GOES imagery over SE KY moving into far SW VA will bring a surge of DPVA and vertical motion through the column, resulting in a deepening of the moisture and a greater potential for what is now largely virga to reach the ground as cloud bases drop. Have retained low chances for measurable precip through this morning, mainly across the S and E CWA. Vertical wet bulb profiles support anything that falls being a few flurries or snow showers, with the best chance in the SE including FAY. Will need to watch this closely this morning, as any measurable wintry precip during the morning rush hour with air temps not far from the freezing mark can make for a bad situation quite quickly. Otherwise, expect copious cloud cover this morning, especially away from the NW CWA which will be influenced by downslope drying. As the vorticity lobe shifts to our east by afternoon, cloud cover should decrease, however residual moisture near the top of the deep boundary layer should allow a few clouds to linger through the afternoon into early evening. Thicknesses remain well below normal, and despite the good mixing today, highs should be chilly, 42-50, well below the normal highs of about 60-67. With the deep mixing and energetic system (including a low tropopause, as the 2 PVU surface is projected to drop below 600 mb), surface winds will be blustery, with gusts up to around 25 mph common today. Skies will be fair tonight with decreasing winds as heights aloft start to recover. Expect cold lows in the mid 20s to around 30. -GIH
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&& .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... As of 255 AM Wednesday... The surface high will move from the central Gulf Coast to over FL during this period, as the powerful mid-upper level low tracks northeast over New England and the Canadian Maritimes. This will lead to continued rising heights aloft and a decrease in mid-upper winds, yielding a neutral-to-sinking and generally dry column over central NC. Low level flow will back to WSW, allowing for some air mass modification, with highs only slightly below normal at 57-65 under fair to mostly sunny skies. But the MSLP gradient and still- strong winds through the low levels (including passage of a 40 kt 850 mb jetlet) will make for another breezy day with gusts of 20-30 mph. Winds will decrease once again Thu evening toward sunset. Then, a backdoor front is expected to sink into the NE and N sections of NC overnight. While this frontal passage will be dry Thu night, increasing moisture streaking NW to SE over the region (and along the frontal zone) will lead to increasing clouds. The frontal zone will increase the range of lows, from low-mid 30s N to low-mid 40s S. -GIH && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 325 AM Wednesday... High pressure to the south will remain in control on Friday keeping the warming trend going with highs in the upper 50s to upper 60s. Much more representative for this time of year. An upper level disturbance will try to approach western areas by late in the day which could cause some increased cloud cover and a slight chance of a shower but very low confidence at this point. On Saturday a messy and very unorganized low pressure system tries to bring some wet weather to the area. Expected cloud cover will keep temperatures generally in the middle 50s. Unsettled weather continues into Sunday as models don`t agree on what will happen with this disturbance/frontal zone. This will make temperature forecasting tricky for Sunday. GFS extended MOS guidance gives a high of 68 for Raleigh which seems highly unlikely given the pattern. Will trend closer to the 60 degrees shown in the ECM guidance. Don`t think either day over the weekend will be a washout but certainly keep an umbrella nearby. For early next week, another strong low pressure system will track just north of the area. Although showing Miller B type characteristics, the proposed P-type transition zone for the current storm track would be north of the area and thus will keep the forecast all liquid for now but this will need to be monitored through the week as some more winter precip could be on our doorstep, at least for northern counties by next Tuesday. With this will come another drop in temperatures to below seasonal norms. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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As of 645 AM Wednesday... VFR conditions are expected over central NC terminals for the next 24 hours, however the passage of a strong upper level disturbance WNW to ESE across the area through this morning will bring a period of lowered (still VFR) cigs and a possible brief snow flurry or snow shower. While any vsbys in such a flurry/snow shower would drop down to MVFR, the chance of this occurring at any particular site this morning precludes mentioning this in the TAF. But aviation interests should be aware of this potential this morning. Additionally, deep mixing will lead to blustery winds today, from the NW at around 10- 15 kts with sporadic gusts to 20-25 kts possible. Winds will diminish toward nightfall. Looking beyond 12z Thu, VFR conditions will hold through late in the work week as high pressure drifts over the Southeast states, although breezy and gusty winds are again expected Thu. 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
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Ellis AVIATION...Hartfield is the U.S. government's official web portal to all federal, state and local government web resources and services.