Key MESSAGE 1, Really not much change in forecast thinking as we will remain rather hot going into this weekend. High pressure ridging will remain centered off the Mid-Atlantic coast allowing for steady SW'rly surface flow outside of daily seabreezes. This will result in rather warm low-level thicknesses overspreading the Carolinas. While NBM guidance continues to be too warm with temps, records will still be in jeopardy, esp FRI (see climate section below for record high info). The caveats each day through this weekend 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 into the upper 60s to low 70s each day with the highest dewpoints being found behind the daily seabreeze as it works its way inland. This will lead to higher humidity and increasing "feels like" temperatures even on the days with convection/clouds. There does look to be a chance for a few showers and thunderstorms today, tomorrow, and on Friday mainly during the afternoon and evening each day. 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 70-90% 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, Once again no real changes to forecast thinking over the next few days. 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 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 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 20-30% 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 on Sat.
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.
18z Wednesday through Monday Primarily VFR forecast expected through the TAF period. Widespread cirrus continues to remain over ENC this afternoon bringing little in the way of impacts to routes. Surface trough and attendant mid-level disturbance will pose a threat for iso to sct showers and thunderstorms after about 21Z and into tonight over Nern routes. Chances have lowered slightly compared to the previous update so do not have a mention of VCSH in any TAF site as of this update, but on the off chance something sneaks into the area, a brief period of sub-VFR conditions is not out of the question. As we get into tonight a similar setup is expected to last night with the potential for MVFR to IFR ceilings with low stratus infiltrating ENC from S/N. Less of a signal tonight especially with steadier SW breezes forecast, but wanted to set the table for the potential and have introduced a SCT deck of low stratus at 1.5 kft after 05Z tonight at OAJ Ewn with ceilings quickly raising around 13 4Z. Will have to monitor if this threat increases and expands northwards to ISO/PGV. Otherwise steady SW winds at 10 kts with gusts up to 15 kts are expected through Thursday afternoon with the only wind shifts occuring behind the seabreeze with more of a turn to the S each afternoon.
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.
Thermal gradient has begin to develop this afternoon allowing winds to increase across waters that currently have ongoing SCA's out. 10-20kt S-SW winds and gusts up to 25 knots noted across coastal waters north of Ocracoke, as well as the Pamlico and Croatan/Roanoke sounds with lighter winds noted elsewhere (closer to 10-15 kts with gusts up around 20 kts). Seas are generally around the 2-4 ft range across our coastal waters as well. Don't expect much change over the next 24 hours with steady SW winds forecast across our area waters at 10-20 kts with gusts up to 20-30 kts. As a result expect SCA's across the Pamlico and central coastal waters to continue into Thurs evening now, but elsewhere we likely get a reprieve late tonight into Thurs morning before wind increase yet again resulting in a threat for additional SCA's on Thursday. Schc to Chc of showers and thunderstorms crossing Nern inside waters after sunset and pushing offshore after midnight
Outlook (Thu night 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 2-4ft 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 until 6 pm EDT Thursday for amz135. Small craft advisory until 8 am EDT Thursday for amz150-231. Small craft advisory from 6 pm this evening to 6 pm EDT Thursday for amz152-154.
