Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | 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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
179 FXUS62 KRAH 281828 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 225 PM EDT Tue Mar 28 2017 .SYNOPSIS... An upper-level disturbance and cold front will push across the region today, and offshore this evening. Weak high pressure will follow the front for tonight and Wednesday. Another storm system approach our area Thursday night and Friday, bringing another round of stormy weather. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 225 PM Tuesday... Little has changed in the forecast philosophy for this afternoon and evening. There continues to be a marginal risk for isolated severe thunderstorms this afternoon. Clearing has allowed for an increase in instability from the Foothills into much of the Piedmont. MLCapes have increased in some areas to near 1000 J/KG over southern VA and portions of the NC Piedmont. Temperatures were rising through the 70s with near 80 at Fayetteville. Dew points were in the lower 50s NW ranging to 60 SE. The wind shift line was located from near Hickory NE to Lynchburg at 200 PM. The main area of instability out ahead of the wind shift line will continue to progress with the wind shift SE into our Piedmont in the next few hours. Cumulus were developing with some organization noted along the wind shift line to our NW. In addition, there was another area to watch from near CLT NE to RDU where another low level boundary was draped. A couple of showers and thunderstorms were already ongoing along these boundaries. Hi-Res models and current data suggest widely scattered thunderstorms will continue to develop along both these features this afternoon as they progress rapidly eastward, exiting the Coastal Plain region by early evening. The favorable instability and timing of the wind shift line is expected to be mainly east of the Triad region; therefore, the isolated severe potential should be confined to the far eastern Piedmont to the coast 20z-23z or so. Even over these areas, MLCapes and many other severe weather parameters especially wind shear are only marginal. Pea to nickel hail may end up being common in most of the stronger cells, with isolated 1 inch hail possible. The action will shift offshore by sunset and dry/quiet conditions will return for tonight. Lows in the 50s.
-- End Changed Discussion --
&& .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... As of 400 AM Tuesday... Quiet weather day on Wednesday as surface high pressure builds in from the north behind the exiting frontal system and an upper level ridge extends northward out of the southern Caribbean. A bit cooler with the airmass change with highs in the low 70s across the northeast to upper 70s in the southwest. Lows are expected to be in the mid 40s across the northeast to middle 50s in the southwest. && .LONG TERM /Thursday through Monday/... As of 345 AM Tuesday... Thu through Sat: The backdoor cold front is expected to settle just south of NC early Thu as cool high pressure noses in from the north. In the mid levels, a shortwave ridge shifts across the SE and Carolinas Thu, while a potent low pushes slowly eastward through the central and southern Plains. Major model differences start to emerge between the GFS and ECMWF Thu, resulting in a low confidence forecast. Both models take the mid level low and trough eastward through the Mid/Lower Miss Valley / Mid South / Gulf States and Carolinas / Southeast through early Sat, however the GFS digs energy into this low much more deeply than what is shown by the ECMWF, and this in part results in notable differences with the push of the front back north through NC, with the more southern-track GFS keeping the front to our south through Thu night (with a cool stable wedge regime in the NC Piedmont) followed by a slow northward push Fri, while the slightly weaker/more northerly ECMWF takes the milder air northward into central NC as early as late Thu. While the high to our northeast is not particularly strong nor is it being significantly reinforced aloft, this air mass should still be dense enough for the cool pool to stay lodged into the NC Piedmont through Thu. Will have highs Thu from the mid-upper 50s NW ranging to near 70 SE, with a slight chance of rain or drizzle in the west with overrunning flow strengthening over W NC as the 850 mb anticyclone shifts off the Carolina coast. As the mid level low/trough crosses the region with a negative tilt, it will be accompanied by a complex occluding surface frontal system, with a more southern track and less potential instability on the GFS (which develops strong forcing for ascent near the E Gulf Coast/FL Panhandle Thu/Thu night) and a more northern track with greater potential instability on the ECMWF. Have generally followed the slightly weaker ECMWF, although both models have been trending stronger with the shortwave trough in recent runs, so confidence remains low. There does appear to be enough moisture (PW of 1.25-1.5") and forcing for ascent, including DPVA, enhanced upper divergence, and low level mass convergence, for a continuation of likely pops, focused on Thu night through Fri evening, tapering down WSW to ENE Fri night into early Sat as the mid level shortwave trough and surface frontal system push to our east with a weak cool front settling southward through the area. Highs from the mid 60s to lower 70s Fri with cloudy skies and numerous showers/storms, and in the low-mid 70s Sat with partial sunshine and rising heights aloft as another mid level ridge axis approaches in the wake of the exiting trough. Sat night-Mon: Expect generally quiet weather Sat night/Sun as weak surface high pressure builds in from the north in tandem with the mid level shortwave ridging. Yet another shortwave trough crosses the S Plains into the lower Miss Valley Sun night into Mon, while the weak frontal zone to our south tracks back northward. Expect fairly seasonable temps Sun, perhaps still a little above normal as the incoming surface high will be cut off from a polar air source. Warmer thicknesses Mon, behind the weak warm front, will be offset with increasing clouds with the trough`s approach, so expect highs from the lower to upper 70s Mon. -GIH && .AVIATION /18Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
As of 145 PM Tuesday... 24 Hour TAF Period: Generally VFR conditions forecast for the KGSO/KINT areas, with VFR elsewhere outside of widely scattered strong thunderstorms between 19z and 23z, mainly from KRDU eastward to the coast. VFR conditions expected tonight and Wednesday with weak high pressure. Long term: A low pressure system will cross the area on Friday through Friday night with the potential for showers and thunderstorms. High pressure with VFR conditions should return for the weekend.
-- End Changed Discussion --
&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...Ellis LONG TERM...Hartfield AVIATION...Badgett

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.