Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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175 FXUS62 KRAH 110502 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 100 AM EDT Thu Jul 11 2024 .SYNOPSIS... A cold front will push slowly east across central North Carolina tonight, reaching the Coastal Plain before stalling out early Thursday morning. This front will push back westward into the Piedmont Thursday, but will generally hold over the western and central Carolinas through Sunday, as it slowly weakens. && .NEAR TERM /THROUGH TONIGHT/... As of 835 PM Wednesday... Scattered showers and thunderstorms have been developing in the past hour or so in the pre-frontal convergence zone out ahead of the approaching cold front. The cold front, which is currently a fine line on radar (no precipitation - wind shift to the NW) will be merging with the convergence zone (where the SE winds become SW). In addition, there is currently analyzed around 2500 j/kg of MLCape in the region around the Triangle to RWI to FAY. Some of the hi-res models continue to suggest a fair amount of thunderstorms around the eastern Triangle into the Coastal Plain in the next couple of hours. There have been some gusty winds with the showers/storms thus far and conditions are favorable for 40+ mph wind gusts in the stronger storms. Otherwise, the front will move into the Coastal Plain later tonight taking these initial POP to the east and dissipating. A decent gradient in overnight lows appears likely tonight, with readings dipping into the upper 60s NW ranging into the mid/upper 70s SE. Some patchy fog and stratus will be possible across the south and east and mid 70s dew points still persist there. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 140 PM Wednesday... Aloft, the longwave trough will remain over the MS Valley through Thu night, while the strengthening Bermuda high slowly ridges westward. Model guidance continues to show an area of low pressure tracking wnwwd around the Bermuda high toward the mid-Atlantic coast Thu/Thu night. At the surface, the surface boundary should retreat westward through central NC Thu/Thu night. Meanwhile, a low could develop along the front off the Southeast US coast Wed night, then drift westward into the SC Thu/Thu night. There is still some uncertainty wrt the timing and track of that system thereafter. As the surface boundary retreats westward and the low aloft approaches, cloud cover and chances for showers and storms will increase over central NC from east to west through Thu night. Rainfall amounts remain a bit uncertain, but still expect highest amounts over the Coastal Plain, lowest over the western Piedmont. There is still a marginal risk for excessive rainfall Thu/Thu night across most of central NC. Highs should range from upper 80s east to mid 90s southwest, but with the higher dewpoints accompanied by rain and clouds, air temps should be decreasing as dewpoints are increasing. As a result, heat index values should top out in the mid 90s Thu. Lows should range from around 70 degrees north and west, to mid 70s SE. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 400 PM Wednesday... Wet weather is expected across central NC on at least Friday and possibly into Saturday, which will hopefully provide some welcome relief from the drought conditions. A front that pushed back west through central NC as a warm front on Thursday night will likely stall somewhere around the Foothills or western Piedmont on Friday. Rich moisture will be in place ahead of the front, with dew points in the 70s and PW values in the 2-2.5 inch range, which is 125-150% of normal. Meanwhile mid-level troughing off the Southeast US coast will induce a weak surface low that moves north across SC and NC on Friday and Friday night. The NHC gives this system only a 10% chance of tropical development with only marginally favorable conditions, but it will still aid with moisture and lift regardless. In addition, a shortwave trough will swing NE from the Great Lakes into southern Ontario/Quebec, and central NC will be in the right entrance region of a southwesterly upper jet on the eastern side of the trough. Low-level convergence along the front will combine with the coastal disturbance and jet influence to result in widespread convection on Friday. WPC depicts a pretty sharp QPF gradient across our area, ranging from just around a quarter inch in the far NW Piedmont to 1- 1.5 inches in the Coastal Plain. Of course, locally higher amounts will be possible given relatively slow storm motion and potential training that occurs. While we have been dry lately, this much rain could still result in localized flooding issues, especially by Friday which will be the second day in a row of potentially heavy rain, so soils will be more saturated and FFG will be lower. Thus WPC has a slight risk (level 2 of 4) for excessive rainfall across most of the area on Friday. Not expecting much of any severe threat given the lack of shear. High temperatures will be below normal, in the lower-to-mid-80s, but lows Friday night will stay mild (lower-to- mid-70s). Precipitation coverage and intensity will begin to decrease on Saturday, but exactly how much is still uncertain. The upper disturbance will pull away, and the highest moisture axis will push near the coast as the mid-level flow turns more WSW. At the surface, the front over the area will start to become more diffuse, and if the ECMWF is to be believed, the low-level flow will turn dry/northwesterly. But the GFS and most of its ensembles keep moist southerly low-level flow for another day and thus have greater coverage of showers and storms. For now have chance to likely POPs across the area, lowest NW and highest SE. Temperatures will get back to near normal with highs in the upper-80s to lower-90s. Sunday through Wednesday will turn drier with POPs closer to climo (20-40%) each day, as the upper pattern gets less active and PW values drop back to near normal. Troughing over the Great Lakes will finally push east into northern New England and the Canadian Maritimes, as broad mid-level ridging extends from the western Atlantic into the Southeast US. At the surface, the stalled front will gradually wash out as low-level flow is from a S/SW direction. The best chances for convection will be focused near the Piedmont trough and sea breeze. While this pattern reduces the flooding threat, it brings back the heat. By Sunday, highs will be back in the lower-to-mid-90s with heat indices in the upper-90s to low-100s. Even hotter conditions are expected from Monday through Wednesday with highs in the mid-to-upper-90s and heat indices reaching 105-110 possible from around the Triangle south and east. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... As of 100 AM Thursday... VFR conditions are expected to mostly dominate central NC terminals through this evening, although a downturn to IFR is likely starting later this evening, esp over central and eastern TAF sites. A few showers in the E, just affecting RWI at this point, is all that remains from the earlier band of storms this past evening, along with sct-bkn MVFR clouds in the far NE and SE near RWI/FAY. These lower clouds should clear out by 08z as a cold front pushes past I-95 and brings drier air in from the W. A few showers and isolated storms are possible in the far E this morning through this afternoon, mainly E of RWI/FAY, with VFR conditions prevailing at the TAF sites through early-mid evening. The front is then expected to push back westward from mid evening through tonight, and an east- to-west trend toward IFR cigs and scattered showers and storms is expected starting around 02z-03z at RWI/FAY and around 03z-04z at RDU, with INT/GSO holding at VFR with dry weather through the end of the TAF valid period. Surface winds will be mainly from the N and NE today, with a few gusts to 15-20 kts through early afternoon, then shifting slowly east-to-west to be from the ENE or E from this evening through tonight. Looking beyond 06z Fri, sub-VFR conditions and numerous areas of showers and isolated storms, including locally heavy rain, will prevail early Fri morning through Fri night at all sites, as the westward moving front slows then stalls over the W Piedmont or Foothills, where it will linger into the weekend. Shower/storm chances will persist, mainly each afternoon through evening and primarily in the E Sat/Sun. Mon currently appears mostly dry with only isolated storms. Morning sub-VFR fog and low clouds are possible mainly E early Sat/Sun with fairly low chances Mon. -GIH && .CLIMATE... Record High Temperatures: July 10: KRDU: 99/1993 July 15: KGSO: 97/1974 KRDU: 99/1997 July 16: KGSO: 99/1915 KRDU: 101/1887 KFAY: 103/1937 Record High Minimum Temperatures: July 10: KGSO: 77/1981 KRDU: 77/1981 KFAY: 77/1998 July 11: KGSO: 75/1992 KRDU: 77/1981 KFAY: 76/2019 July 12: KGSO: 76/2011 KRDU: 78/2011 KFAY: 80/1935 July 13: KGSO: 75/2017 KRDU: 78/2017 KFAY: 78/2017 July 14: KGSO: 77/1981 KRDU: 77/2017 KFAY: 80/2017 July 15: KGSO: 74/2019 KRDU: 76/1992 KFAY: 78/2015 July 16: KGSO: 75/2010 KRDU: 77/2010 KFAY: 78/1992 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Badgett/Luchetti SHORT TERM...Hartfield LONG TERM...Danco AVIATION...Hartfield CLIMATE...RAH