Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 241955 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 355 PM EDT MON OCT 24 2016 .SYNOPSIS... A dry cold front will move across central North Carolina this afternoon and evening. High pressure will extend into the region tonight and persist through late Wednesday. A cold front will drop southeast across the Mid Atlantic on Thursday. && .NEAR TERM /through tonight/... As of 320 PM Monday... The incoming cold front is on pace to drop SSE through NC through the remainder of the afternoon into early-mid evening hours. Expansive high pressure centered over north central Canada will then extend SE post-front, building into the area tonight. A relatively dry column ahead of and along the front, noted on WV imagery and upstream soundings from this morning, in tandem with little substantial forcing for ascent, continues to support a dry frontal passage with few clouds. Later tonight, the kinematic structure on forecast soundings (including fast mid-upper level WNW to NW flow) along with observed patchy upper level moisture upstream over the Midwest suggest the potential for another rough of orographically enhanced cirrus over the NC Foothills and western Piedmont late tonight, and have indicated this with a bit more cloud cover across the western portion of the forecast area, although confidence is not high enough in the density of any such clouds and resultant impact on reducing radiational cooling to adjust lows upward beneath the cirrus. Apart from a few gusts with and just behind the frontal passage through mid evening, surface winds should gradually decrease overnight as they veer to northerly or north-northeasterly. Expect lows of 40-46 with moderate radiational cooling under mostly clear skies. -GIH && .SHORT TERM /Tuesday through Wednesday night/... As of 330 PM Monday... Quiet and fairly uneventful through mid week. A portion of the surface ridge settles over central NC and modifies somewhat on Tue, then is followed by a weak reinforcing boundary dropping southward through NC Tue evening, and cool Canadian-rooted high pressure nosing in from the north through Wed. This ridge axis will be capped by an 850 mb anticyclone which will drift from the Mid South ESE across the Southeast states through Tue night before shifting off the coast late Wed. Further aloft, the mid levels will remain subsident and warming as a large vortex centered over the Canadian Maritimes and encompassing much of NE NOAM drifts NE and fills with weakening flow over our region as a shortwave ridge builds in from the west through Wed. All of this equates to little or no lift or moisture and a generally weak surface flow. The only issue of concern is the presence of the chilly ridge axis overhead Tue night accompanied by clear skies and light winds, fostering radiational cooling and bringing about the risk of patchy frost. Statistical guidance has trended slightly cooler in spots, and with otherwise favorable conditions, will introduce patchy fog over portions of north central NC with lows in the upper 30s. Otherwise, expect somewhat cool highs Tue/Wed in the mid-upper 60s. The surface ridge will then shift east off the coast Wed night with a light return flow helping to drive surface dewpoints back up through the 40s Wed night. Lows in the mid-upper 40s with mostly clear skies. -GIH && .LONG TERM /Thursday through Monday/... As of 350 PM Monday... Shortwave troughing will extend from south central Canada through the Great Lakes to the Mid South early Thu, shifting eastward Thu into Thu night. This will be accompanied by a strong surface low crossing the Great Lakes (and culminating in a triple point low over E PA and NJ) Thu through early Fri, and a trailing cold front that will drop SE through NC Thu night/early Fri. We will briefly be in the warm sector Thu, which will help drive up thicknesses to near or just above normal with temps expected to warm up into the upper 60s to mid 70s. Moisture depth does improve with PW reaching near 1.25", with decent mid level DPVA and minor upper divergence, although along-front mass convergence is apt to be small. Will retain chance pops Thu afternoon, peaking Thu night before departing early Fri morning. Projected instability appears minimal, and will keep it at just showers for now. The active northern stream across the north central and northeast CONUS/Mid-Atlantic persists through the rest of the week, with the aforementioned trough strengthening to a closed mid level low over MI Thu before shifting east and off the Northeast coast by early Sat, and another closed low close on its heels over the weekend. Another high pressure ridge builds into NC and overhead through Sat morning before shifting to our SE Sat afternoon in response to this fast flow. Expect minimal cooling Fri as the cooler thicknesses barely work into NC, then a warmup back into the 70s is anticipated Sat as we again get into return flow on the back side of the departing surface ridge. The next front pushing in from the north is likely to drop into or through NC on Sun or Sun night, but this too should be moisture-starved. Expect highs to cool back down a bit Sun and a bit more Mon, into the 65-70 range. The way-too-early outlook for Halloween night appears to be dry, with seasonable to slightly cooler than normal temps. -GIH && .AVIATION /18Z MONDAY THROUGH FRIDAY/... As of 205 PM Monday... High confidence of VFR conditions through the 24 hour TAF period. A cold front will move southeast across central NC this afternoon and evening with a cool and dry high pressure center building into the region overnight and Tuesday. The result will be mainly clear skies through Tuesday afternoon with just a few wisps of cirrus clouds at times on Tuesday. Westerly winds at around 10kts with a few gusts to 15kts this afternoon will become northwest at around 5 to 10kts behind the front through this evening and then veer around to light northerly tonight and then northeasterly on Tuesday. looking further ahead... High pressure will extend into the region through late Wednesday resulting in fair weather. An approaching cold front on Thursday and the return flow ahead of it could trigger a few showers and perhaps some early morning low stratus resulting in a chance of adverse aviation conditions. Fair weather with perhaps some gusty winds can be expected on Friday and Friday night. -Blaes && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Blaes NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Hartfield AVIATION...Blaes is the U.S. government's official web portal to all federal, state and local government web resources and services.