Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 080656 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 156 AM EST FRI Dec 8 2017 .SYNOPSIS... A nearly stationary front will remain offshore of the NE Gulf of Mexico to off the Carolina coast into Saturday. Several waves of low pressure will track along the front later tonight into Saturday. A cold front will move east across the region late Saturday, followed by cold and dry air. && .NEAR TERM /THROUGH TONIGHT/... As of 1022 PM Thursday... Next batch of shortwave energy and re-newed/increasing upper level divergence within the right entrance region of a 150 kt jet in place across the Mid-Atlantic States, on the cyclonic-downwind side of the high-amplitude positively-tilted trough across the Central US, is allowing the northern edge of the precipitation shield that stretches from the southeast TX to the SE NC coast to spread back into southern and southeastern portions of the forecast area, with eventually filling westward into central Piedmont by daybreak. Dual-pol products indicates mixed precipitation within the narrow bright band moving across the Sandhills and Coastal Plain counties, that has been confirmed by recent a observation at KPOB metar and a public social media report at Goldsboro. While high precip rates could cool the vertical temp column to support a brief mixture of rain mixed with sleet or snow, the main p-type will be rain overnight. With BL temperatures remaining above freezing overnight, ranging form mid to upper 30s northwest to near 40 SE, there will be no impacts or accumulations. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... As of 240 PM Thursday... ...Some wet snow is still possible across portions of Central NC Friday night and early Saturday although accumulations will be limited... Primary changes to the previous forecast are a slight increase in surface temperatures, decrease in snowfall accumulations and a slower exit of precipitation out of the area on Saturday. Still expect Central NC to be under the influence of deep southwesterly flow aloft as a strong upper level trough to the west swings eastward toward the region. Several disturbances in the flow aloft will move over the area on Friday while the trough axis remains west of the area. At the surface, Central NC will be sandwiched between the stalled front off the Mid-Atlantic coast and an arctic front to the west. With the high in an unfavorable location, the best push of cold air will likely get hung up along the mountains. The models have trended slightly warmer, which results in higher thicknesses and lower chances for snow to fall or accumulate. Though we could see some wet-snowflakes mix with rain across the NW Piedmont Friday, much of the precipitation will fall as rain through the daylight hours. Near surface temperatures in the upper 30s will keep any snow from accumulating on what is an otherwise warm ground. By Friday evening-night, nocturnal cooling and strong lift in a saturated dendritic growth zone will likely result in precipitation rates strong enough for snow to occur where temperatures are in the 32-36 degree range(northern and northwest Piedmont). The thermal profile will determine why type of precipitation actually falls, and right now there is still uncertainty surrounding what exactly that profile will look like. There has been a trend, as there tends to be in Central NC, for a warm nose aloft to develop. As of the latest model runs, the Triad should be all rain or snow through the period, with the thermal profile remaining at or below 0C through the column. Farther to the east, the temperature profile has a more prominent warm nose, and remains near isothermal around 0C below it, which would result in all rain. There may be a sweet spot between the Triad and Triangle where some sleet and snow may fall and accumulate a bit on the elevated and grassy surfaces. However, with temperatures at or above freezing and the residual warmth at the surface, do not expect significant impacts to result. Any precipitation beyond 15Z should be all rain, which will progress eastward out of the area by Saturday night. This will be an event where the cold air is chasing the rain, thus expect most of the precipitation to fall as liquid, except where brief period of snow may mix in as mentioned above. Liquid equivalent precipitation totals will range from less than a quarter of an inch in the northwest to around 2 inches in the southeast. Given the warm ground and boundary layer, snow will have a difficult time accumulating except for on elevated and grassy surfaces and under high precipitation rates. Generally less than an inch of snow is expected at this time, primarily between midnight and 7 AM Saturday. Best chances for accumulating snow along a line from Burlington to Oxford, generally be along and west of I-85. Highs on Friday in the upper 30s to low 40s with overnight lows in the low to mid 30s. With the rain and clouds sticking around longer on Saturday, highs will be similar to Friday, low to mid 40s. && .LONG TERM /SUNDAY THROUGH THURSDAY/...
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As of 155 AM Friday... Dry weather is expected for the medium range period, with below normal temps (some days much colder than others). Surface high pressure will build/extend into the area from the Deep South/Gulf Coast States behind the exiting deep trough Sunday. This will result in a brief warm up through Monday and dry weather, with highs on Sunday in the upper 30s NW to the lower to mid 40s SE. Highs Monday are expected to be in the mid to upper 40s, with some lower 50s across the south. The mid/upper level trough across the eastern half of the country is expected to reload by Tuesday, sending another deep/potent mid/upper disturbance and associated generally dry cold front through the area Tuesday. This will result in a renewed push of cold and dry air on Wednesday, with high temps again plummeting into the 30s and 40s. Moderating surface high pressure will build into the area again on Thursday, resulting in moderating temps by Thursday, with highs in the 40s and 50s.
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&& .AVIATION /06Z FRIDAY THROUGH TUESDAY/... As of 120 AM Friday... 24 Hour TAF Period: Another round of rain is overspread the area this morning, with precip expected to expand and continue on an off through the day. Precip has move into southern and eastern portions of the already this morning, with precip expected to spread into the Piedmont through around daybreak Friday. Sub-VFR conditions are expected to develop as the dry low level air mass saturates this morning, allowing for cigs to fall into the IFR/MVFR range. Cigs may fall into the LIFR range late today/this evening. With regard to precip type, we will likely see a rain/snow mix at KGSO/KINT this morning, before changing over to all snow on by mid morning. We may see a brief period of rain mixing in again with the snow during the late afternoon/early evening at KGSO/KINT, before turning over to all snow again late in the evening. Further east at KRDU, a mixture of rain/sleet is expected by early this morning, changing to a rain/snow mix by daybreak (with possibly bursts of all snow), with all rain expected by late afternoon/evening. At KRWI and KFAY, only rain is expected. For locations that see snow, expect we`ll see IFR and possibly LIFR visbys in addition to the cigs. Outlook: Sub-VFR conditions and precip will continue tonight into Saturday. Snow may mix with the rain at the eastern TAF sites on Saturday morning as well, before ending on Saturday afternoon. A return to VFR conditions are expected by late weekend into early next week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...CBL SHORT TERM...KC LONG TERM...BSD AVIATION...BSD/Badgett

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