Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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974 FXUS62 KRAH 082252 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 752 PM EDT Wed May 8 2024 .SYNOPSIS... A series of upper level disturbances will interact with an unseasonably moist airmass over North Carolina through early Friday, bringing unsettled weather. A cold front will move across the region on Friday, ushering in drier and less humid air for the weekend. && .NEAR TERM /THROUGH TONIGHT/...
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As of 752 PM Wednesday... The SVR Watch is being trimmed back on the northwest flank leaving only Hoke, Scotland, Cumberland, and Sampson Counties in the Severe Thunderstorm Watch in our SE zones. We are watching upstream for the next potential for later this evening and overnight in which the guidance continues mixed on whether anything significant reaches our region.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 245 pm Wednesday... * Slight/Level 2 Threat continues into Thursday... The chance for severe storms on Thursday hinges highly on how convection evolves tonight. A couple rounds of storms are possible tonight, the latter of which is expected to be a larger MCS moving into NC overnight. That deep convection should overturn the atmosphere and reduce the currently steep lapse rates aloft and ultimately reduce updraft strength on Thursday. However, guidance isn`t exactly consist on how far east the line will track or how far north it will extend. The 12z NAM suggests the storms may weaken significantly before reaching the coastal plain, and thus forecast soundings from FAY to RDU and east still show a solid 2000 MLCAPE on Thursday afternoon. GFS soundings show a similar profile. In the wake of the MCS, dying or not, there should also be some subsidence to subdue convection, but otherwise the trailing outflow effective front may end up across the southern CWA and serves as a focus for development, along with lee troughing ahead of the approaching synoptic front and perhaps even another disturbance approaching from the Deep South (which models tend to take south into the Southeast state along with an MCS). Deep layer shear will continue to be strong as the upper jet edges eastward along with the upper trough and 500mb winds increase to 40- 50kt. There is a big discrepancy between the CAMS and the coarser NAM/GFS/ECMWF. Most HREF members show every little redevelopment of convection on Thursday and focus activity across SC and further southwest, while the NAM/GFS/ECMWF suggest quite a bit of convection in their QPF. Tend to lean toward less coverage but with a conditional severe threat where convection does develop. Highs should range from the mid 80s nW to around 90 SE. Lows in the low to mid 80s. Friday is another tricky forecast day, as multiple days of possible convection should continue modify the local airmass, but larger scale forcing will be better as the positively tilted trough over the Midwest and Mid-Miss valley today swing east toward the Mid- Atlantic states. The limiting factor will be instability given that the cold front is expected to have shifted across the southern CWA, with highs dipping back into the mid 70s to lower 80s and lower dewpoints infiltrating the Piedmont. Again, and conditional threat for severe storms seems possible but confined to areas closer to the SC border. Cooler and drier air is expected behind the front as it finally pushes through the area Friday, but favor the warmer side of low temp guidance in the lower 50s for Friday night. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 215 PM Wednesday... Sat begins with broad troughing over generally the Northeast CONUS characterized mainly by two embedded shortwaves, one of which is shifting out over the western Atlantic while the second dives ESE out of Upper Great Lakes and into the Ohio Valley by Sat afternoon. The former will have shifted the axis of deep, rich moisture (PWAT ~1.6 inches) well offshore and usher in PWAT values around 0.5 of an inch (near the 10th percentile for GSO, RNK, MHX RAOB) driven by briefly strong subsidence and downsloping flow WNW flow. The latter shortwave will pivot across Mid-Atlantic Sat afternoon and evening, but central NC may only see glancing synoptic forcing from this feature as the better DPVA remains north of the VA border. Point soundings suggest shallow afternoon cumulus development to the base of the subsidence inversion with better 700mb moisture (deepening the moisture layer) moving into the area late Sat afternoon into the evening hours. This may be enough to squeeze out some sprinkles over central NC with better chance for very light rain closer to the NC/VA border. Surface high pressure and a secondary area of subsidence on the backside of the departing trough will lead to dry conditions Sun through Mon with temperatures in the 70s to low 80s. The next system will move towards the area Mon night into Wed as a closed low near the Four Corners Region Sun morning slowly drifts eastward. Closed lows situated in between a split-flow regime often have timing issues, and this one is no exception. Latest forecast gradually brings in precipitation early Tues morning with chances lingering into Wed with greatest chances diurnally favored during the afternoon/evening. It would not be surprising to see the quicker GEFS trend towards the slower EPS and precipitation onset becoming 12 hours later than is currently forecast. Temperatures will trend back towards above normal mid-level height rises and the 850mb anti- cyclone shifts offshore. && .AVIATION /00Z THURSDAY THROUGH MONDAY/...
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As of 750 PM Wednesday... The first round of storms is currently passing mostly from FAY south and east. Generally VFR conditions are expected elsewhere through late evening into the overnight. There is the potential for another round of storms overnight. In addition, stratus is expected to develop across much of the region between 09z and 13z. Looking beyond 13z Thu, high uncertainty in the details of showers and storms and their impacts lingers through Thu. Generally VFR conditions should develop after the stratus burns off mid to late morning. Otherwise, a chance of showers/storms into Friday as the cold front moves through. Then VFR conditions expected this weekend.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Badgett SHORT TERM...BLS LONG TERM...Swiggett AVIATION...Badgett