textproduct: Newport/Morehead City

WHAT HAS CHANGED

Scattered strong to severe thunderstorms possible late this afternoon into tonight.

Updated aviation discussion.

KEY MESSAGES

1) Scattered strong to severe thunderstorms are possible late this afternoon and into tonight. Best window between 4PM-12AM. The main threat will be damaging winds, with potential for an isolated tornado, small hail, freq lightning and locally heavy rain.

2) Seasonable and dry mid to late week. Another front will approach the area this weekend, becoming unsettled again late weekend into early next week.

DISCUSSION

KEY MESSAGE 1...An anomalously strong upper level trough amplifies over the eastern US today, with a potent shortwave dives southeast through VA and the Carolinas. A strong LLJ ahead of this feature should lead to increasing moisture advection, with PWATs once again climbing back above 2". Meanwhile, heating of a moist boundary layer should support moderate instability, with MLCAPE rising into the 1500-2500 j/kg range. Aloft, a notable upper jet max is forecast to overspread the instability axis, supporting deep layer shear of 30-45kt. While instability will be moderate, the shear/instability/forcing combo is notable for this time of year. This combination supports the threat for severe weather, with modest support from ensemble, analog, and machine learning guidance. The main potential limiting factors are timing and potential subsidence, with area remaining capped through much of today. Some guidance suggests convection may not reach ENC until after sunset. Despite the potential for a gradually stabilizing boundary layer, if strong large-scale forcing is realized, it should help support deep convection well past the typical diurnal max in convective intensity this time of year. Storm mode could be a bit messy, with combination of supercells early ahead of more organized multicell line segments later. Given the potential amount of forcing present, it appears likely that a MCS will move through the eastern Carolinas and VA during the evening and early overnight hours posing a risk of damaging winds. Low- level SRH around 100-200m2/s2 may support a few rotating updrafts capable of hail and tornados. However, those latter 2 hazards should be lower compared to the wind risk. While convection looks to be fairly progressive, heavy rain in a high PWAT airmass could pose a localized flood threat, esp for areas that have received heavy rain over the last few days (Hyde county east through the Outer Banks).

Ahead of the convection, hot and humid conditions are expected, with heat indices rising to 100-105 degrees for portions of the area. Still looks too marginal for heat advisory at this time.

KEY MESSAGE 2...Cold front will push offshore early Wed morning, with sfc high pressure building in from the west while troughing continues aloft. This will keep temps seasonable and mostly dry through late week. The next frontal system will impact the area this weekend into early next week, with increasing precip chances.

AVIATION /10Z TUESDAY THROUGH SATURDAY/

Mix bag of conditions across the terminals early this morning with areas of fog and low stratus. Higher confidence in widespread stratus and areas of fog through sunrise, with greatest probabilities along and west of Hwy 17. Periods of dense fog possible at times. Area will remain mostly dry today, with shower and thunderstorm chances increasing late afternoon and into the first part of tonight. Strong to severe thunderstorms possible, with the main threat of damaging wind gusts 45-65 mph. Storms will grad push offshore late tonight. SSW winds will gusts 15-20 kt this afternoon and evening.

Outlook (Wednesday through Saturday): Much drier behind the fropa for Wed into the end of the week as high pres rebuilds. Periods of early morning fog and/or stratus possible each night.

MARINE

Latest obs show light winds less than 10 kt across the waters, with seas 2-3 ft. SSW winds will increase through the day, 10-20 kt by late afternoon with seas building to 2-4 ft. SSW winds will peak at 15-25 kt gusting 20-30 kt tonight, with seas building to 4-7 ft. Expanded SCA to the Pamlico Sound and portions of the central waters. Scattered strong to severe thunderstorms will be possible late this afternoon into tonight. These storms will be capable of 40-50 kt winds, small hail, waterspouts and frequent lightning.

Outlook: Modest NW wind surge 10-20 kt behind the front Wed with seas grad subsiding. Light to moderate NW winds continue Thu with 2-4 ft seas. Flow becomes more southerly late Fri and Fri night.

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...Small Craft Advisory from 6 PM this evening to 4 AM EDT Wednesday for AMZ135. Small Craft Advisory from 8 PM this evening to 8 AM EDT Wednesday for AMZ152-154. Small Craft Advisory from 5 PM this afternoon to 8 AM EDT Wednesday for AMZ156-158.