Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 210635 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 135 AM EST Tue Nov 21 2017 .SYNOPSIS... High pressure will drift offshore late tonight and Tuesday. A weak area of 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 1020 PM Monday... No changes made to previous discussion, slight adjustment to temperatures based on the latest observations but general forecast thinking remains the same for tonight. An area of high pressure at the surface will extend across the eastern third of NC through the night. While sfc winds will be near calm east of highway 1, a light sly return flow on the back side of the high will occur over the southern-western Piedmont. Aloft, patchy cirrus will traverse overhead in the sw flow. The cirrus will become thicker towards morning in advance of an upper level disturbance that will cross the northern Gulf. Cool dry air associated with the sfc high will permit temperatures to quickly cool into the 30s by mid-late evening. After midnight, temperatures should stabilize as the high clouds thicken and a light sly flow develops over the Piedmont. Min temps should be fairly uniform, mostly in the lower 30s, and around 30 degrees at the normally colder locations. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 234 PM Monday... A southern stream short wave, currently located over the western GOM, will move to the northeast and across the Carolinas during the afternoon and evening Tuesday. A resulting sfc low is still progged to move northeast along the Gulf Stream late Tuesday and Tuesday night. The latest GFS has trended farther east with the deepest moisture and best rain chances. The NAM is a bit farther west, but it too has shifted slightly east with the better moisture. The latest ECMWF is about the same as its prev run...generally showing some light overrunning precip basically from US-1 eastward quickly moving through Tuesday evening. So for now, will shift highest pops a bit eastward, basically along and east of I-95 with lesser rain chances back west toward the Triad. Either way, this light rain event Tuesday evening will be short lived with limited rainfall amounts, and other than the usual wet road hazards, should be fairly low-impact. Given the late-day timing of the rain, we should see some sunshine during the morning, however clouds will be on the increase as we head through the afternoon. Highs from the mid-upr 50s northwest to mid 60s southeast. Tuesday night, the next front will move into our CWA as the next northern stream short wave moves by to our north. The fropa is expected to be dry given the drying in the wake of the earlier southern stream wave. CAA will be somewhat delayed with the next high delayed, so given prefrontal flow and clouds, look for warmer lows Tuesday night ranging from the lower 40s northeast to around 50 southeast. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... 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. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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As of 135 AM Tuesday... Sfc high pressure over the area this morning will drift eastward and offshore throughout the day. Low-level dry air associated with this high will support a continuation of VFR conditions through at least 18z, with the resultant SELY return flow leading to gradual moistening and broken/overcast ceilings between 3 to 5kt during the mid to late afternoon. Strengthening low-level moisture advection in advance of a sfc low that will move northeast off the SE Coast overnight, is expected to lead to deteriorating aviation conditions this evening and overnight, especially at the eastern terminals(KRWI and KFAY). Model guidance continues to exhibit higher than average spread with this coastal system, and thus forecaster confidence is lower than normal. Expect ceilings to lower to IFR to MVFR with patches of light rain/drizzle from RDU eastward. It`s possible that KINT and KGSO could also see a period of sub-VFR ceilings during the late afternoon/early evening, however confidence is too low to include in TAFS at this time. A cold front will cross central NC Wednesday. Cold dry air advection will quickly scour out any sub-VFR ceilings Wednesday morning. VFR parameters should prevail across central NC Wednesday afternoon through Saturday.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...KC/WSS SHORT TERM...np LONG TERM...Franklin AVIATION...CBL

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