Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 271912 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 310 PM EDT Tue Jun 27 2017 .SYNOPSIS... A moisture-starved cold front will exit central NC this evening. Canadian high pressure will follow and extend over the Carolinas and southern Virginia Wednesday and Wednesday night. && .NEAR TERM /Through Tonight/... As of 310 PM EDT Tuesday... During the mid-late afternoon, a threat for isolated showers and possibly thunderstorm will exists across roughly the eastern half of the forecast area as a mid level s/w approaches from the west. While moisture is limited through the atmosphere, lift associated with height falls of 30-40m, and slight low level instability may be sufficient to trigger isolated convection between 19Z-23Z. The mid level s/w will exit central NC early this evening. Subsidence in the wake of this feature along with a north-northwest low level flow will aid to diminish the cloud coverage. Mostly clear skies should rule overnight. Canadian high pressure will build into the region. the air mass associated within the high is notably cooler and drier. This drier cooler air mass and a near calm sfc regime at the surface should allow temperatures to drop into the 50s overnight across the Piedmont, and near 60-lower 60s across the Sandhills and southern coastal plain. && .SHORT TERM /Wednesday and Wednesday night/... As of 310 PM EDT Tuesday... An area of high pressure at the surface coupled with rising heights aloft translates to dry and pleasant conditions for Wednesday and Wednesday night. The sfc high will deposit a dry air mass over central NC, maintaining dewpoints int the 50s. After the seasonably cool start, afternoon temperatures will rebound into the low-mid 80s. The center of the high will drift offshore by early Thursday evening, initiating a return sly flow across the NC Piedmont. Thus, dewpoints will start to inch upward indicative of the return of low level moisture. Still, under mostly clear skies, overnight temperatures will remain comfortable for this time of year, generally near 60-lower 60s. && .LONG TERM /Thursday through Tuesday/... As of 300 PM EDT Tuesday... A subtle upper level low in vicinity of the TX gulf coast this afternoon is progged to meander slowly NE into the Deep South on Thu before deamplifying/lifting NE across portions of the Carolinas on Fri. Expect dry conditions to persist on Thu, followed by an increasing potential for convection Fri afternoon/evening as the deamplifying upper wave lifts NE across the Carolinas and southerly return flow strengthens (temps/moisture rebound toward climatology). Cyclonic flow aloft will strengthen over the eastern US this weekend as a potent upper level low (currently in Alberta) digs SE into the Great Lakes (Sat) and lifts NE across New England (Sun). Broad troughing aloft will suppress/confine the sub-tropical ridge to the FL peninsula and aid in the development/maintenance of a pronounced surface trough east of the Appalachians over the weekend. With the above in mind, expect above normal chances for convection and near normal temperatures Sat/Sun. Forecast confidence decreases early next week. Several MCS`s are expected to develop upstream of the region Mon/Tue as shortwave energy in NW flow aloft progresses from the Rockies into the Central Plains/Central MS River Valley. In general, temperatures are expected to increase as flow aloft over the Mid-Atlantic weakens/flattens and the previously suppressed sub- tropical ridge expands northward from FL into the Deep South/ Southeast, and the relative best potential for convection should shift along/east of the Hwy 1 corridor, though coverage/timing may ultimately depend on the evolution of upstream MCS`s. -Vincent && .AVIATION /18Z Tuesday through Sunday/... As of 110 PM EDT Tuesday... VFR parameters expected across central NC through Thursday. An upper level disturbance and attendant sfc front will cross central NC this afternoon, and exit our region early this evening. This weather feature will cause an increase in mid/upper level cloudiness, along with a threat for isolated showers and possibly a thunderstorm. The convective threat appears highest along and east of highway 1. Even so, with coverage expected to be no worse than isolated, threat appears too minimal to include in the aerodrome forecast for KFAY and KRWI. Clouds will decrease this evening with mostly clear skies anticipated overnight, persisting Wednesday through early Thursday. An increasing sly low level flow late Thursday into Thursday night will usher moisture into our region, leading to the probability of low cloud cover by early Friday morning. These low clouds, if they occur, should burn off by mid morning. A persistent low level sly flow is expected Friday through Sunday, leading to an increasingly wet atmosphere and increased chances for sub-VFR parameters. This will lead to periods of low clouds and patchy fog each morning and a chance for scattered afternoon-evening convection each day. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...Vincent AVIATION...WSS is the U.S. government's official web portal to all federal, state and local government web resources and services.