Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 222330 RRA AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 630 PM EST Wed Feb 22 2017 .SYNOPSIS... High pressure will continue to ridge west into the Mid-Atlantic as the center remains offshore. A slow-moving upper level trough will cross the Southeast and Mid Atlantic states through tonight. An upper level ridge will again briefly build over the eastern U.S. Thursday and Friday. && .NEAR TERM /THROUGH TONIGHT/... As of 235 PM Wednesday... Closed southern-stream low over the northern GOM will move east- southeastward across southern Florida and the Keys late tonight through early Thursday. With the system suppressed well to our south, weak forcing via weak upglide and weak DPVA will support ample cloudiness, but very little in the form of rain in the form of patchy rain/isolated showers for the remainder of the day and into the evening. In-situ wedge in place across the NW Pied that developed in response to the batch of light precip that moved earlier this morning and that will likely be sustained by stratus cloud cover within the weak upslope flow will result in a rather NW to SE temperature gradient, ranging from upper 50s/lower 60s NW to mid 70s SE. Skies will remain mostly cloudy overnight, which will support another mild night under light southerly flow. Lows 50 to 55. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 235 PM Wednesday... Strengthening synoptic scale subsidence with a mid to upper level ridge building into the area in the wake of the closed low moving off the Florida coast will give way to increasing sunshine throughout the day. Weak sely onshore flow will prove of little consequence as enhanced mid-level moisture stream moves offshore while remaining capped aloft. Thus, will keep forecast dry. With the erosion of the in-situ wedge across the NW Piedmont, the warmth that central and eastern sections experienced today will spread to all of central NC on Thursday. A projected 10 meter low-level thickness increase will support highs ranging from lower 70s NW to upper 70s SE, which will approach record territory(see climate records below). Lows in the 50s. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 430 PM Wednesday... Fri/Fri Night: Expect rising heights aloft Fri as a shortwave ridge builds eastward across the region in the wake of an upper level low progressing offshore the FL/Atlantic coast. In the lower levels, an offshore surface ridge will extend inland (SW/WSW) through the Carolinas. Despite near record highs (near 80F) and an unseasonably moist airmass characterized by surface dewpoints in the low/mid 50s, precipitation (e.g. convection) is unlikely due to insufficient forcing and a strengthening mid-level (~700 mb) cap marking the leading edge of a modified elevated mixed layer advecting into the region from the SW (on the western periphery of the shortwave ridge as it progresses toward the Southeast coast Fri aft/eve). Expect dry conditions and unseasonably warm temperatures to persist with lows in the mid 50s. Sat/Sat Night: An upper level low moving ashore the Pacific coast this evening will track eastward through the Intermountain West/Rockies on Thu and emerge in the central Plains on Friday. The upper low will amplify as it tracks into the OH valley Friday night and may become negatively tilted as it progresses through the Mid- Atlantic on Sat. An attendant sfc cyclone will track NE from the Great Lakes into Canada, with a secondary cyclone developing offshore the Mid-Atlantic coast (Sat) racing northward to the Canadian Maritimes by 12Z Sunday. A cold front associated with the Great Lakes /inland/ low will approach the mountains from the west Sat morning and track across central NC during the day Sat. Though upper forcing will be present, the strongest DPVA is expected to remain north of central NC (over the DELMARVA) and will likely lag behind the pre-frontal trough. Additionally, with the primary sfc low lifting NE from the Great Lakes into Canada and a secondary low developing offshore, expect little in the way of return flow, with sfc dewpoints similar to Friday and a persistent (albeit weakening) mid-level cap as a modified elevated mixed layer advects eastward across the region. At this time it is difficult to tell whether or not sufficient upper level forcing will be present, let alone favorably juxtaposed with low-level forcing and diurnal heating. As a result, it is difficult to ascertain whether or not convection will develop over central NC Sat afternoon. At this time, the best chance for precipitation appears to be in the NW Piedmont 12-18Z Sat when remnants of an OH/TN valley squall line (if any) would be expected to track into northwest NC. Otherwise, the atmosphere appears too dry/capped for convection to develop (though if did, supercellular organization would be likely). Expect highs in the 70s, lows Sat night in the upper 30s (NW) to lower 40s (SE). Sun-Wed: Expect relatively dry conditions in this period with temperatures gradually rising through the 60s into the 70s early next week, in advance of the next cold front expected to approach from the west mid-week. -Vincent && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 630 PM Wednesday... 24-Hour TAF period: The advection of warm moist air into the region will continue through the TAF period. As a result, overcast skies will prevail and the weak isentropic upglide over the western terminals (KINT/KGSO) will also continue. As a result, the best chances for MVFR and possibly IFR visibilities and low-end VFR to possibly sub-vfr cigs through tonight will be at KINT and KGSO. The remaining sites should remain VFR through the period, however there is a slight chance for a brief period of borderline VFR/MVFR visbys around daybreak. Winds overnight will be calm to light and variable. Conditions should return to VFR across all terminals Thursday morning with generally southerly winds around 5 kts and prevail through the end of the TAF period. -KC Looking ahead: Aside from some early morning fog/stratus, expect predominately VFR conditions through early next week. The exception will be a very isolated/small chance of a shower or thunderstorm as a cold front moves through the area Saturday afternoon. Winds will become breezy Saturday afternoon as the front approaches from the west, with sustained winds between 15 to 20kts, gusting 25 to 30 kts. -CBL && .CLIMATE... Record High Temperatures February 23rd February 24th February 25th GSO 73/1980 79/1982 81/1930 RDU 79/1980 81/1982 82/1930 FAY 80/1922 83/1930 85/1930 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...KC/Hartfield NEAR TERM...CBL SHORT TERM...CBL LONG TERM...Vincent AVIATION...KC/CBL CLIMATE...RAH

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