Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 210207 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1007 PM EDT SAT AUG 20 2016 .SYNOPSIS... An upper level trough and attendant cold front will approach the region from the west tonight, then progress east across the Mid- Atlantic and Carolinas Sunday into Sunday night. && .NEAR TERM /TONIGHT/...
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As of 1000 PM Saturday... Mid to upper level ridging will continue to expand E across the Carolinas tonight, between a shortwave trough that exited the Middle Atlantic coast Sat morning and a much larger positive tilt trough now extending from central Canada to SRN CA. In the lower levels, a NW to SE-oriented trough axis/weak remnant frontal zone remains evident in surface and 925-850 mb RAOB data from WRN VA to east-central NC; and the models indicate this low level focus for lift will gradually retreat NEWD into ERN VA and ERN NC by Sun morning. Ongoing scattered convection across central NC appears to be a result of convergence into, and weak WAA atop, this low level frontal zone. As such, this focus for (scattered) showers and storms should likewise move through the ERN half of the RAH CWFA tonight. While several bands of disorganized showers and storms are lined up generally along and W of the Appalachians, this activity will likely diminish as it moves E through an increasingly nocturnally-cooled environment over the WRN Carolinas. Satellite imagery indicates deep-layered cloud cover should be less than previous nights owing to the aforementioned mid to upper level ridging building overhead, with associated partly cloudy conditions supportive of some glimpses of the lingering Perseid meteor showers. Persistence lows in the lower to middle 70s.
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&& .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... As of 250 PM Saturday... The upper trough moving through the OH Valley on Sunday will propel a long-awaited cold front across the area Sunday evening. Moderate instability (highest east) should unfold ahead of the front giveN another day of ~90/72, and a bit stronger mid-level flow (30-35kt) downstream of the trough should also favor better organization to convection. However, the core of the associated vort max will pass well top our north, and the front and trough axis will cross the area during an increasingly less favorable time frame between 21z and 03z. thus, the prospects of an organized convective event appear low, with a low-end severe threat more likely in a more favorable environment toward the VA border. Highs 88-92 Sunday afternoon, with lows dipping into the mid 60s in the northwest Piedmont behind the front Sunday night and near 70s to the east. && .LONG TERM /MONDAY THROUGH SATURDAY/... As of 310 PM Saturday... Surface high pressure will build in to the area on Monday and move off the coast on Wednesday, bringing a drier and slightly cooler airmass. Highs will be a few degrees below normal through Wednesday... in the mid 80s. The high will shift offshore on Wednesday, as upper level heights increase, and temps will begin to rebound to normal. Shortwave moving in to the Ohio Valley on Wednesday moves northwestward and dampens as it encounters the ridge along the east coast. Attendant front will likely remain north/west of the area before weakening, keeping conditions dry in to the weekend. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 745 PM Saturday... Convection has waned across the area, with only isolated showers for the remainder of the evening. Aside from some localized fog/stratus at KRWI, expect predominately VFR conditions overnight with broken cirrus overspreading the area in advance of the approaching trough. On Sunday, a cold front will approach from the west and cross the area between 21z and 03z Monday. Westerly flow preceding the front will limit pops/coverage, especially across eastern and southern terminals. Looking ahead: High pressure in the wake of the frontal passage will advect much drier air into the area Monday through midweek, promoting VFR conditions through the period. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...VINCENT NEAR TERM...MWS SHORT TERM...SMITH LONG TERM...SEC AVIATION...CBL

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