Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 150704 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 305 AM EDT Tue Aug 15 2017 .SYNOPSIS... A nearly stationary front will extend across the Carolinas through Thursday, before lifting north of the area as a warm front Thursday night. A cold front will approach from the northwest on Friday. && .NEAR TERM /TODAY THROUGH TONIGHT/... As of 245 AM Tuesday... Deep moisture over the Carolinas is evident on GOES-16 layer water vapor imagery. A string of subtle mid level perturbations riding across western and northern NC and adjacent VA has been partially responsible for the showers and embedded storms impacting the Piedmont in the last few hours, as is a weak upper divergence maximum associated with a broad upper jet from OH to off the Northeast coast. These forcing features are on pace to shift off the Mid Atlantic coast and away from our area later this morning, which should result in a relative lull in convection for a few hours from late morning into mid afternoon. Another weak but discrete vorticity maximum, located over western portions of the KY/TN border early this morning, will shift eastward and merge into the base of an amplifying trough shifting through the St Lawrence Valley and New England late today into this evening. This should work with marginal to moderate instability to support scattered to numerous showers and storms later this afternoon, moving ESE through central NC into the evening before exiting the SE CWA overnight. This motion will correspond with a weak Piedmont surface trough that will push slowly SE today, and to the S and E of the forecast area tonight. Will trend pops up to likely for a brief period late this afternoon, then trend down NW to SE tonight, leaving just slight chances SE late. While the morning areas of stratus and patchy fog will be slow to lift this morning due to weak winds slowing dispersion, some insolation today will allow temps to peak in the 85-90 range. Lows tonight 70-75. -GIH && .SHORT TERM /Wednesday and Wednesday night/...
-- Changed Discussion --
As of 305 AM Tuesday... The weak surface trough will settle near or just south of the NC/SC border through Wed, as a very band of mid level vorticity streaks across western and southern NC. MUCAPE is expected to be marginal in the NW and moderate SE, and with PW values holding at or just over 2.0" in the SE only with values slipping to 1.5" elsewhere, combined with weak deep layer winds, shower/storm chances look rather small over all but the SE portion of the forecast area in the afternoon. Chances look similarly low after loss of heating from mid evening through the overnight hours Wed night, with only southern and southwestern sections expected to see a few showers overnight. With partly cloudy skies, highs should be in the upper 80s to lower 90s. Lows Wed night 70-74. -GIH
-- End Changed Discussion --
&& .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 244 AM Tuesday... Expect a fairly unsettled and uncertain extended period, with low forecast confidence. Thursday and Thursday night, a upper level trough off the Carolina coast and approaching upper level trough from the northwest will result in primary convection development along the Carolina coast and in close proximity to the mtns, leaving much of Central NC primarily dry. Highs in the upper 80s to low 90s and lows in the low to mid 70s. Friday and Friday night: High pressure will build off the Southeast U.S. coast and over the desert southwest as the upper level trough amplifies over the OH/TN valley. The usual Piedmont trough will set up over the region ahead of the approaching cold front, and with increasing southerly flow into the area will provide a focus for convective development. Chances will be higher in the aft/eve, although depending on the timing of the approaching cold front, could linger into the overnight hours. Temperatures similar to Thursday, highs in the low to mid 90s and lows in the low to mid 70s. Saturday onward: Forecast confidence decreases significantly for this time frame. The approaching cold front moves into Central NC on late Friday night into Saturday, where it could stall into early next week as the parent low moves off to the northeast and the upper level trough deamplifies. For now, expect convection to be diurnally driven and primarily along the surface boundary. Highs will steadily decrease through the period, into the mid 80s by Tuesday. Lows will also exhibit a downward trend, into the upper 60s and low 70s by Monday and Tuesday nights. Eclipse Forecast: Taken with a grain of salt given that this is still several days away, expect partly cloudy skies and chances for showers and storms over Central NC. Better chances for clouds and rain farther south and in proximity to the surface boundary. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... As of 1255 AM Tuesday... Showers and storms with locally heavy rain and IFR to briefly LIFR conditions will impact INT/GSO/RDU until around 08z. There is a high probability of IFR to LIFR cigs, most likely between 08z and 12z, along with MVFR vsbys, at all sites early this morning. Cigs will then lift gradually lift through the MVFR category 12z-16z before becoming VFR. With a very moist and unstable air mass in place, development of showers/storms is likely after 16z INT/GSO and after 18z RDU/FAY/RWI, lasting until 00z-03z before pushing to the SE and decreasing in coverage. Winds will be light and variable, under 8 kts, except gusty and erratic in/near storms. Looking beyond 06z Wed, dry weather is expected after 06z through mid morning Wed. Best chance of showers/storms Wed afternoon will be in east sections, near RWI/FAY, but in general Wed into Wed evening should be dry for most places. Otherwise, a very moist, humid, and unsettled pattern will hold in place through much of this week, as a weak frontal zone holds across the Carolinas. There will be a good chance of showers and storms Thu-Sat, most likely from mid afternoon through the evening, as well as a good chance of early morning sub- VFR stratus and fog at all sites. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...KC AVIATION...Hartfield is the U.S. government's official web portal to all federal, state and local government web resources and services.