Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 271738 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 138 PM EDT Mon Mar 27 2017 .SYNOPSIS... A warm moist southerly flow will hold over the area through Wednesday. An upper level trough will cross the region beginning late tonight through Tuesday, bringing unsettled weather. A backdoor cold front will drop southward through the area late Wednesday through Wednesday night. Another storm system will cross the area Thursday night and Friday. && .NEAR TERM /THROUGH TONIGHT/... As of 1010 AM Monday... The band of light showers was slowly weakening and dissipating over the eastern Piedmont and northern Coastal Plain late morning. Rainfall this morning has been generally less than a tenth of an inch with this band. We will update the weather and POP grids to indicate scattered showers closer to the Interstate 95 corridor with a few isolated showers possible over the western Piedmont through around 18Z. This afternoon, it appears that a lull in showers will occur, supported by current data and by the Hi-Res convection allowing models, as the focus for storms will shift well to our west over the Tennessee Valley with the next short wave trough. This trough will set off strong to severe thunderstorms over TN/AL this afternoon and evening with weakening storms likely advancing into the NC mountains tonight. Before that time, a few showers/isolated thunderstorms may develop this afternoon - with a low chance POP warranted into the Triad region. Satellite data indicated some breaks developing over much of the Piedmont, with stratus confined to the NW Piedmont and Foothills. This is expected to burn off by early afternoon. Partly sunny skies will lead to increased mixing with SSW winds 10-15 mph. Highs should warm into the 70s to near 80 in the Sandhills. Readings in the N and E Piedmont and N Coastal Plain may be tempered a few degrees due to the slower clearing. Tonight, increasing POP later over the western third of the region with the convective threat increasing. Otherwise, very mild SW flow and at least partly cloudy skies will lead to lows around 60 (15-20 degrees above normal). && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 330 AM Monday... Tuesday and Tuesday night low pressure currently over the Arklatex area will track north of the area through the mid-Atlantic states and bring a very weak cool front with it. Maybe a bit better chance for thunder Tuesday afternoon, especially in the central and eastern portions of the forecast area as instability look a little better than on Monday afternoon and low-level lapse rates remain very steep. The proximity of the low to the north will provide upwards of 25-30 kts of bulk shear to work with. As a result SPC, currently has the forecast area in a marginal risk for severe thunderstorms. While damaging wind should remain the primary threat, some better CAPE values aloft could result in some small hail. Temperatures will continue to be in the upper 70 to low 80s across the forecast area on Tuesday afternoon with lows in the mid 50s. && .LONG TERM /Wednesday through Tuesday/...
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As of 145 PM Monday... Wed-Wed Night: With shortwave ridging aloft, expect mostly sunny to partly cloudy skies and above normal temps in the mid/upper 70s Wed afternoon. Subsidence in the wake of an upper level low moving offshore New England Wed evening will result in pressure rises along the eastern seaboard as an inverted sfc ridge extends southward through the Mid-Atlantic into the Carolinas, the leading edge of which will be marked by a backdoor cold frontal passage /wind shift to the NE at ~15 mph/. Lows Wed night will be determined by the precise timing of fropa. At this time, expect temps ranging from the mid 40s NE Coastal Plain to lower 50s in the SW Piedmont. Thu: NE low-level flow in the wake of the back door cold front early Thu morning will gradually veer to the E/ESE during the day, allowing temperatures to recover into the mid 60s across the Sandhills and SE Coastal Plain Thu afternoon. A cold air damming wedge is expected to develop across portions of the N/NW Piedmont where broken/overcast cloud cover (and possibly evap cooling attendant intermittent light rain or sprinkles in the foothills) are largely expected to offset diurnal heating, keeping highs in the mid 50s, coolest in Forsyth/Person county. Thu night: Expect an increasing potential for showers across the western half of the state (primarily along/west of Highway 1) between midnight and sunrise Fri as an upper level low progresses into the OH valley and low-level warm advection strengthens downstream over the Carolinas. Expect lows Fri morning ranging from the mid/upper 40s to lower 50s, coolest in the W/NW Piedmont where precipitation /evap cooling/ is more likely. Fri-Fri Night: Confidence in the evolution of the aforementioned upper level low, attendant sfc cyclone and associated fronts (warm/cold/wedge) remains below normal for several reasons, ranging from antecedent conditions (CAD wedge in place across portions of central NC Fri morning) to significant disagreement amongst the GFS/ECMWF. The 12Z GFS suggests the upper level low over the central MS river valley on Thu will track east across the Carolinas/VA late Friday/Friday night. In stark contrast, the 00Z ECMWF shows the upper level low deamplifying and lifting NE through the lower Great Lakes into New England late Fri/Fri night. While the precipitation forecast appears to remain on track (e.g. a solid potential for showers across the entire area during the day Friday), significant uncertainty is present w/regard to the intensity of convection/ amount of precipitation. From a hazardous weather standpoint, the 12Z GFS solution would favor a potential for severe storms whereas the 00Z ECMWF solution would not. The temperature forecast on Fri/Fri night is challenging to say the least. At this time will show the coolest temps in the Triad (highs in the lower 60s) and warmest temps in the Sandhills and SE Coastal Plain (lower 70s). A clearing trend from SW-NE is expected in the wake of a cold frontal passage late Fri night, though the timing thereof remains in question. At this time anticipate lows in the lower/mid 50s, coolest NW Piedmont. Sat-Sun night: Confidence in the forecast for Sat has decreased, with the 12Z GFS guidance now showing a potential for showers assoc/w DPVA digging SE on the western periphery of the upper level low tracking offshore the Mid-Atlantic/Carolinas. The 00Z ECMWF suggests dry conditions and a warm-up with the upper low deamplifying/lifting into New England and clear skies in the wake of the cold front on Sat. Dry conditions and further warming are expected on Sun as a shortwave ridge aloft tracks across the region from the west. Mon-Tue Night: Expect increasing cloud cover during the day Monday and a chance for convection by Tue as the next upper level low /attendant sfc cyclone/ approach from the west. -Vincent
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&& .AVIATION /15Z MONDAY THROUGH FRIDAY/...
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As of 1010 AM Monday... 24 Hour TAF Period: Generally VFR CIGS expected this afternoon, with MVFR CIGS and VSBYS with showers/isolated thunderstorms expected to spread eastward into the region after 06Z/tonight. Lower IFR CIGS with showers likely between 06Z-12z/Tue, especially at KINT/KGSO/KRDU. This should spread into the KFAY and KRWI areas Tuesday. A return to VFR conditions is expected Tuesday night and Wednesday, with the exception of IFR to LIFR fog and stratus potential during the early morning Wed. Long term: A storm system is expected to push into the region Thursday night and Friday with showers, low CIGS, and fog.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...Ellis LONG TERM...Vincent AVIATION...Badgett

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