Key MESSAGE 1, Very warm low-level thicknesses are forecast to overspread the Carolinas from mid-week on as we get into a WSW low- level flow pattern. Nbm guidance continues too warm with temps, however, records will still be in jeopardy, esp FRI (see climate section below for record high info). The caveats each day will be the coverage of convection (see KEY MESSAGE 2 for additional details), and the potential for high clouds/convective debris. Both of those factors can have significant impacts on the temperature forecast each day. Regardless, persistent SWerly flow will allow dewpoints to steadily rise through the 70s each day. This will lead to higher humidity and increasing "feels like" temperatures even on the days with convection/clouds. The chances for afternoon convection remain Thu and Fri, but coverage is expected to be limited. Fri will start already relatively warm with early morning MinTs 10deg above Normal, and low level thicknesses will continue to increase. Probabilistic guidance currently shows a 50-70% chance of exceeding 95 degrees for inland areas away from the coast. This combined with dewpoints in the low 70s suggests a widespread area of AppTs of ~105deg. This setup could lead to the first heat headlines of the summer season. The NWS' experimental Heat Risk guidance shows much of ENC in the major category, with a few areas nearing the extreme category.
KEY MESSAGE 2, Synoptic pattern is expected to shift towards something more favorable for convection across ENC esp this weekend with a weak front crossing the FA SAT and stalling to the S of the area, and into early next week when troughing aloft develops, opening moisture transport from the Gulf. However, this shouldn't be read as a high coverage of thunderstorms each day. In fact most of the day will be rain free, but as is typical in convective season in ENC, hit and miss storms are going to dot the area each afternoon through early evening.
Firstly, an upper level shortwave is forecast to move through the Mid- Atlantic and Carolinas late tonight and push offshore in the early morning THU. This wave is forecast to interact with a moistening and gradually destabilizing airmass, supporting clusters of convection from VA S into the Piedmont of NC. Locally, temps aloft will be very warm, with 850 temps of 15-20C. This will have a tendency to support some residual capping, and may tend to lead to a weakening trend with any convection that approaches our area from the W/NW. Given the increased forcing with the wave, though, it stands to reason that at least some weak, elevated convection could survive into the area, and the forecast reflects this potential for WED evening for a potential weakening MCS with 30% chances for showers or storms. Very warm temps aloft may continue to cap a greater coverage of convection into FRI, and thus afternoon spotty rain chances are only 20%, so slightly below climo.
Friday night, stronger showers and thunderstorms developing to our W may reinvigorate over the area when the prefrontal trough interacts with the seabreeze as works over the Coastal Plain. Some of these storms may be strong enough to carry strong winds and maybe some hail, and as such, SPC has outlined the bulk of the state of NC in a marginal risk (lvl 1/5) for severe thunderstorms.
Temps aloft "cool" slightly as heights aloft fall ahead of the front and the stout mid level ridge begins to weaken, and this may support at least a risk of higher coverage seabreeze convection.
Early next week, higher than climo shower and storm chances are in the forecast with the greater moisture content through the column leading to PWATs in excess of 2in. Additionally, deep layer shear of around 30-35kt along the front may support a modest increase in the potential for organized convection, some of which could be on the strong side.
06z Wednesday through Sunday Fun nocturnal TAFs tonight with increased moisture compared to previous nights potentially brining an end to the long period of VFR flight cats we've had for the last few days. Cirri likely to plague skies through the period in light south to SWerly flow, which should preclude fog formation for the bulk of the area. Where winds go light, mainly over SWern corners of the FA, fog could develop. Any fog that does develop is expected to be patchy, but could be enough to bounce VIS to MVFR or IFR levels. As such, have introduced a TEMPO IFR BR group for OAJ, though MVFR VIS may persist longer. There is a signal for low stratus (MVFR with a low risk of IFR level) to advect from S to N in a pool of low- level moisture, most prominent along and west of the I-95 corridor, which could threaten inland TAF sites PGV/ISO. Will continue sct mention of MVFR decks for these sites, but will monitor conditions closely with tempo IFR groups potentially needed. Any stratus likely to burn off by 14z with increasing southwesterly flow after sunrise today, gusting up to 15 kt at times in the afternoon. Surface trough and attendant mid-level disturbance will pose a threat for sct showers and thunderstorms after sunset and into tonight over Nern rtes. Have introduced VCSH mention for PGV this cycle.
Outlook (Thu through Mon): Risk of showers/storms is quite low Thu and Fri, but not 0. Better chance for afternoon/evening showers/storms this weekend into early next week, with tempo reductions in vsby and/or cigs accompanying the heavier showers.
Entering a more typical summertime pattern through the end of the work-week with high pressure centered offshore. Swerly winds 10-15kt and seas 2-3ft@ predominantly 8-9sec. Thermal gradient leads to increase in nearshore winds, strongest over Eern Pamlico Sound, Croatan/Roanoke Sounds and adjacent coastal waters around Cape Hatteras and NOBX. Scas have been issued for these areas. Schc to Chc of showers and thunderstorms crossing Nern inside waters after sunset and pushing offshore after midnight
Outlook (Thu through Mon): A typical summertime regime, with swrly gradient flow maxing out between 21Z and 06Z each evening leading to marginal 25+ kt winds gusts in the favored areas mentioned above. Seas of 3-5ft will be common. The risk of thunderstorms will increase late- week into early next week, with best chances in the late afternoon to evening hours. A front will cross SAT and stall to the S. Low pressure will develop along the boundary and lift back Nward across the Carolinas early next week.
Nc, none. Marine, small craft advisory from 3 pm this afternoon to 9 am EDT Thursday for amz135. Small craft advisory from 3 pm this afternoon to 8 am EDT Thursday for amz150. Small craft advisory from 6 pm this evening to 6 pm EDT Thursday for amz152-154.
