Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 010739 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 240 AM EST Thu Dec 01 2016 .SYNOPSIS... A cold front will cross the area early this morning. High pressure will then build over the Eastern U.S. from the west through the upcoming weekend. An approaching upper level disturbance and increasing moist flow from the Atlantic and Gulf will bring increasing rain chances beginning Sunday night. && .NEAR TERM /today through tonight/... As of 225 AM Thursday... The cold front has just cleared the northwest CWA, where clouds have cleared out, winds have taken on a primarily westerly component, and dewpoints have fallen into the 40s. Such changes will progress steadily eastward for the balance of the night, with the remaining light showers over the eastern Carolinas including our far SE sections (oriented along the departing 850 mb jet) ending in the next few hours. The continental surface high that will build in behind the front from the WSW today is sufficiently modified such that this initial post-front drop in temps won`t be extreme, with slightly above normal thicknesses supporting seasonably mild highs of 59-68 under plentiful sunshine and lighter (yet still periodically gusty) winds. The generally clear skies will continue through tonight; however, a weak shortwave trough located over the Front Range early this morning is projected to track quickly across VA tonight, potentially bringing a few high thin clouds as mid level winds remain rather brisk. Overall, though, expect fair skies at most overnight, with a slackening MSLP gradient yielding light winds. Expect lows of 32-39. -GIH && .SHORT TERM /Friday through Friday night/... As of 240 AM Thursday... Forecast soundings show deep dry and stable air across Central NC on Friday, with a fairly flat and fast mid level flow and high pressure still building in at the surface, leading to generally sunny skies. As this southern stream surface high begins to merge with the larger Canadian high to its NNW, low level thicknesses will drop further on Friday, to around 10-15 m below normal, so temps should follow suit with below normal highs of 53-60. High clouds are expected to being increasing Friday night, spreading in ahead of convection over TX and the lower Miss Valley (ahead of the digging low over NW Mexico). These initial high clouds should be thin however as they encounter the destructive effects of broad ridging over the Gulf States and Southeast, and thus they should do little to impede radiational cooling. Lows 30-35. -GIH && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 252 PM Wednesday... In the Sunday time frame...moisture advection out of the Gulf will stream east along a frontal zone setting up across the Gulf States. With a cool dry airmass in place, we should see a thickening cloudiness Saturday night with light rain breaking out due to isentropic lift in the west by mid day Sunday, and will maintain ongoing chance PoPs in the west during the morning spreading over the east during the afternoon. Highs will be subsequently suppressed by clouds and evaporative cooling, ranging from mid 40s in the northwest to lower 50s in the southeast. The forecast from Sunday night onward remains low confidence pending consensus as to the progression of a cutoff low over northern Mexico which will be lifting ENE across the plains early next week. Initially, the high pressure over the area is reinforced by the arrival of a second surge of cool dry air from a transitory surface high oriented more classically from New England south down the east coast, which would suppress moisture southward on Monday. This would set the stage for another isentropically induced rain regime on Tuesday/Wednesday as the moisture associated with the aforementioned cutoff low and associated surface reflection ride up the cooler denser air. Will keep PoPs on the low chance side for now, with highs in the 50s Monday through Wednesday as we wait to see how the scenario plays out. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... As of 105 AM Thursday... Widespread MVFR cigs have given way to VFR at INT/GSO as the cold front approached from the west. Similar improvement is expected at RDU/RWI/FAY between 08z and 11z, with VFR conditions areawide by 12z, as the cold front sweeps through the area and high pressure begins to build in from the west. Current surface winds from the SW at 10-15 kts gusting occasionally to 20-25 kts will veer to westerly then northwesterly later this morning with diminishing speeds to around 10 kts and infrequent gusts to 15 kts, lasting into the afternoon as VFR conditions persist. Winds will diminish further after 22z late today, with VFR conditions holding through tonight. Looking beyond 06z early Fri morning, VFR conditions will hold well into the weekend as the ridge of high pressure builds into the area. High clouds will spread in from the WSW on Sunday, and these clouds will thicken with lowering bases to MVFR then IFR Sunday night as an upper level disturbance approaches from the WSW, in conjunction with increasing low level moisture from the Atlantic and Gulf. MVFR to IFR cigs/vsbys will persist through Monday with light rain developing. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...MLM AVIATION...Hartfield

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