Key MESSAGE 1, Positively tilted upper level trough/shortwave pushing through the Mid Atlantic states per latest H2O vapor imagery. At the surface, a cold front will track across the Carolinas and then linger around the area on Monday before lifting north as a weak warm front.
Out ahead of the the cold front, a warm and moist airmass has developed acrs ENC promoting MLCAPE vals up to 1,000 J/KG per latest RAP analysis. At the same time deep layer shear will increase to 25-35 kts through early evening. As we get into the mid afternoon, sea breeze convergence inland will aid and work in tandem with aforementioned approaching cold front. Showers and thunderstorms will start out isolated along the seabreeze but then quickly increase in coverage and intensity later this afternoon across the Coastal Plain as the seabreeze interacts with the incoming cold front, and this activity will then push towards the coast and offshore tonight. Some of these storms could become strong to severe in nature bringing a damaging wind and small hail threat within the strongest storms. Latest SSCRAM and HRRR Neural Network svr probs indicate a 10-15% chc of svr winds centered roughly between the HWY 17 and 264 Corridors, which makes sense given maritime airmass keeping coastal areas more stable. Pops remain 60-80% late afternoon into early evening. As bkn convective line moves towards the coast this evening, a weakening trend expected, but trailing stratiform rain will bring very beneficial rain to a good chunk of ENC with amts likely over 0.50" for many. Href PMM QPF values show amounts as high as 1-1.5 inches, which would likely occur where convective training occurs over a short duration. Rain will end through the overnight, with only some diurnal showers redeveloping on Mon as front gets hung up and moves north as weak warm front. Pops remain in the 20-40% range for Mon.
KEY MESSAGE 2, An anomalously strong ridge will remain in place across the Southeastern CONUS through Wednesday, with NAEFS standardized anomalies around 2-3 standard deviations above normal for the time of year across the area. As a result this will continue to bring well above avg temperatures to Eastern North Carolina with near record to record high temperatures possible on Tue/Wed out ahead of an even stronger cold front (See CLIMATE Section below). Biggest threat for breaking records will be across inland locations as relatively cool water temps should moderate high temps in the 60s and 70s near the coast.
KEY MESSAGE 3, Guidance has been surprisingly consistent with the forecast for later this week showing a deep neutral to negatively tilted upper level trough approaching and tracking across the Eastern Seaboard on Thursday. At the surface a rapidly deepening low pressure system will be tracking NE'wards across the Great Lakes and Interior Northeast while its associated strong cold front sweeps E'wards across the Mid- Atlantic and Southeast. Ahead of this front, strong southwesterly winds will help bring up moisture, with PWATs modeled to be in the 1.25-1.5" range. While there will be ample forcing, there is still a fair amount of uncertainty on exact timing of the front which is typical given how far out the frontal passage is. Modeled CAPEs are quite low, and thus a threat for thunder is less than 15% for most areas, with 20% or higher relegated to just the OBX and eastern Downeast Carteret in vcnty of the warmer Gulf waters. Given the impressive dynamics of this system, elected to not use NBM winds for Thursday as they appear to be much too low. Current forecast has wind gusts 30-35 mph. Behind the front cool, dry air moves in for Thursday night/Friday.
02z Monday through Friday SHRA and TSRA will continue to impact ENC for at least another few hours. The highest TSRA risk looks to be focused from KOAJ to KEWN through 03z, then the risk should begin to decrease areawide after that point. Attention then turns to the potential for low CIGs/VIS tonight into Monday morning. In the wake of the ongoing SHRA and TSRA, guidance shows a strong signal for IFR conditions developing after 05z tonight. I stayed fairly close to the previous forecast, but adjusted the timing some based on the latest guidance. It appears that tonight will be more of a stratus issue and less of a FG issue, but we'll continue to monitor this potential in case the FG risk were to increase. Low CIGs/VIS should improve during the day on Monday, with VFR conditions expected by Monday afternoon.
LIFR PROBABILITY (late tonight into Monday morning): 50-70% for all terminals.
Outlook, A front will likely stall near the region continuing to bring chances for sub-VFR conditions to ENC through Tue (mainly periods of fog and stratus) before widespread VFR conditions officially return on Wed. Sub-VFR may return Thursday with scattered to numerous showers.
Swrly winds 10-20 kt SW'rly winds across our inland waters with and 25-30 kt gusts along our coastal waters over the warm Gulf Stream. In addition to this, seas have built to 5-7 ft over the Gulf. Sca remains in place through this evening. A cold front will gradually push offshore bringing widespread showers and thunderstorms to our waters. Some stronger wind gusts possible esp inland rivers and sounds before convection weakens as it approaches the waters south of Oregon Inlet. As front pushes offshore the gradient will ease allowing for SW'rly winds to decrease down to 5-10 kts with gusts up around 15 kts. Seas will also fall closer to 3-5 ft later tonight ending the ongoing SCA's by 2AM Mon.
Sea fog remains in place over portions of Pamlico Sound and coastal waters N of Hatteras, but expectation is for the showers and tstorms reaching the waters here to clear the densest sea fog out. Sea fog is forecast to persist through the overnight, however VIS is forecast to remain above marine dense fog criteria. Fog may become denser closer to sunrise with winds laying down and showers clearing out and another advisory may be needed MON am.
Outlook (Monday through Friday): Benign boating conditions forecast through Wed with widespread 5-10 kt winds and 2-4 ft seas forecast. However, a stronger front will likely cross the waters Thursday. Sw winds will strengthen ahead of the front Wed night with SCA conditions likely (Gales over the warmer Gulf Stream). Winds turn nwrly and remain gusty later Thur behind the fropa. Winds and seas diminish rapidly Thu night and esp Fri as dry high pres builds overhead.
Nc, none. Marine, small craft advisory until 2 am EDT Monday for amz152-154. Small craft advisory until 11 pm EDT this evening for amz156- 158.
