Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 201912 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 210 PM EST Mon Nov 20 2017 .SYNOPSIS... High pressure over the area today will shift offshore late tonight and into the day on Tuesday. A weak low pressure will develop off the Florida coast on Tuesday, and then track quickly northeastward along the Southeast coast Tuesday night. A cold front will move through the area on Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 1145 AM Wednesday... Latest surface analysis shows surface high pressure centered near Charlotte with a mainly light northwest surface flow across central NC. The air mass across the region is quite dry as noted by the 12Z KGSO RAOB which sampled a precipitable water values of 0.18. Current forecast is in good shape with only minor adjustments needed to remove or delay the arrival of some cirrus clouds toward evening and to lower surface dew points which have dipped into the teens in the Triad. -Blaes Previous discussion from 640 am... High pressure and a deep dry air column will dominate today with nary a cloud in the sky until the arrival of some thin cirrus clouds late this afternoon/early evening. It will be a chilly start this morning, with 12z low-level thicknesses averaging around 20 to 23 meters below normal, more typical of late December as oppose to mid/late November. Highs today a good 5 to 7 degrees below normal, ranging from mid 50s north to upper 50s/near 60 south. Aforementioned thin cirrus Monday evening will spread north and possibly thicken tonight within the increasing SWLY flow aloft, in response to a southern stream shortwave trough advancing east across the western and central GOM. Meanwhile, high pressure over the area, will quickly scoot east and offshore. The NAM is quicker with the onset of southerly low-level moisture return late tonight, advecting a stratus cloud deck into southern/southeastern portions of the forecast area during predawn hours. Lows in the lower to mid 30s. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 340 AM Wednesday... The aforementioned southern stream shortwave trough over the GOM will progress eastward across the Florida peninsula during the day on Tuesday, and then lift northeast along the SE Coast Tuesday evening/night. The associated weak spin-up of surface low pressure area over the eastern GOM will quickly track NE up the SE coast, remaining offshore. This wave will support yet another quick hitting- light precip event across the area late Tuesday afternoon and Tuesday night, with bulk of measurable precip expected to remain along and east of US 1, where low-level moisture transport will be strongest. Expect QPF amounts to range from a trace across the western Piedmont a tenth of an inch across the Coastal Plain counties. Under a thickening cloud cover, temperatures will range from lower to mid 50s across the NW Piedmont to lower/mid 60s SE. Much warmer overnight lows in the lower 40s NW to near 50 SE. && .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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As of 210 PM Monday... A surface cold front with limited moisture will be making its way through the region Wednesday and Wednesday night. High pressure and its associated cold airmass to the north will expand into North Carolina on Thursday. A brief warmup will occur Friday into Saturday ahead of the next cold front that will pass through Saturday night. Very amplified trough in the eastern US Sunday and Monday will bring a much colder airmass into North Carolina with max temps Monday only in the 40s. Precipitation during this time frame will be limited to spotty light rain with each frontal passage. Waves of low pressure off the southeast US coastline will keep more substantial rain to the east and south of the region.
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&& .AVIATION /18Z MONDAY THROUGH SATURDAY/... As of 120 PM Monday... VFR will continue through the 24 hour TAF period, with increasing high clouds tonight. Low level misture advection will occur beginning mid-day Tuesday. Sfc winds through Tuesday will be variable at less than 10 kts. MVFR ceilings are possible Tuesday afternoon through early Wednesday as an area of low pressure skirts northeastward up the Southeast U.S. coast. VFR parameters will return on Wednesday and should remain VFR through the majority of the upcoming week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...Blaes/CBL SHORT TERM...CBL LONG TERM...Franklin AVIATION...np/cbl

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