textproduct: Newport/Morehead City

WHAT HAS CHANGED

Risk of rainfall Wednesday has trended downward. Timing of late week frontal passage has slowed to Thursday night into Friday.

KEY MESSAGES

1) Conditional severe thunderstorm risk this afternoon and evening

2) Lower risk of showers and thunderstorms expected across eastern NC Wednesday and Thursday with next higher-end threat Thursday night and Fri ahead of strong front.

3) Dangerous heat likely to return late week.

DISCUSSION

KEY MESSAGE 1...The latest surface analysis this morning shows a stationary area of low pressure near Cape Lookout. A stationary frontal boundary extends northeast up to Cape Hatteras, then turns southeast out into the Atlantic. A subtle upper level shortwave is forecast to cross the Carolinas later today and tonight which should act to lift the low and front north across the inner/outer banks of ENC this afternoon and evening. While significant deepening of the low is not anticipated, there may be just enough low-level turning along the track of the low and warm front to support an area of marginal 0-1km SRH of around 75-100 m2/s2. Meanwhile, SBCAPE of 1000- 2000j/kg and seasonably strong deep layer shear of 40kt+ should be more than supportive of thunderstorm organization. Guidance is mixed on if deep convection will develop. However, given the environment, any deep convection that manages to develop should have the potential to become supercellular in nature with an accompanying wind, hail, and tornado risk. Given the marginal nature of the environment for tornadoes, any tornado that were to develop should be weak/short-lived. This is definitely not a slam-dunk setup, but it's worth monitoring.

KEY MESSAGE 2...The next best chance for stronger storms remains Thursday night into Friday ahead of a stronger front where deeper shear will likely be present along with strong instability as temperatures soar back into the 90s and humidity remains oppressive. Like previous days, better kinematics and thus higher risk of organized convection will likely be to our north in the Mid- Atlantic. Medium- range AI NWP guidance still highlights much of the Carolinas for a severe risk during this period. The primary threat risk is damaging winds, but other hazards remain on the table.

KEY MESSAGE 3...Relatively cooler temperatures will prevail again today with more overcast skies and ENC on the cool side of the frontal boundary. This reprieve will end tomorrow as the boundary lifts northward tonight into Wednesday. As alluded earlier, increasing southwesterly flow ahead of the late-week front will boost low- level thicknesses and kick temperatures into the mid to upper 90s by Thursday. Paired with Tds in the low to mid 70s, heat indices will climb back to around 105+. The passing front may cool things down briefly for the weekend, but medium range guidance suggests excessive heat will remain a concern starting next week.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

A weak area of low pressure will lift north through ENC this afternoon and evening, and will combine with the seabreeze to support SCT SHRA and TSRA. How far inland the seabreeze gets will likely determine what, if any, TSRA risk develops for the main TAF sites. A PROB30 has been maintained for KEWN where the chance remains the highest. Elsewhere, the chance is lower, and we'll hold off on introducing PROB30 or TEMPO groups for now. Otherwise, occasional SCT to BKN low CIGs will remain possible through Wednesday morning. It appears that the most likely timeframe for sub-VFR CIGs is between 09z-15z Wednesday. Light and variable winds this afternoon will give way to a more dominant southwesterly wind during the day Wednesday.

Outlook: More widespread TSRA threat returns Thursday night and especially Friday with a stronger front. Overnight fog and stratus threat possible each morning. Weekend is trending drier and more quiet with predominant VFR expected.

MARINE

A weak area of low pressure is forecast to move slowly north through the central and northern waters through this evening. Along the track of the low there will be a risk of thunderstorms with waterspouts and strong winds to 40kt. Some hail may occur as well. In the wake of the low, building southwesterly winds are expected, with a period of 25kt winds possible for the coastal waters south of Cape Lookout. It looks like the greatest risk of 25kt winds will be over a relatively smaller area of the southern coastal waters, therefore a Small Craft Advisory is currently not planned. Elsewhere, east winds of 5-15kt will become southeast as the low passes, then become southwesterly by tonight. Seas of 2-3 ft are expected north of Cape Hatteras through tonight, with higher seas of 3-5 ft south of Hatteras.

Outlook (Wed through Sat): Periodic nocturnal and early morning risk of showers and thunderstorms is possible each weeknight, although most likely odds will be Thursday night into Friday ahead of stronger front approaching area waters. This front will also be the next focus of widespread SCA conditions with an increasing risk of Gales across the outer waters.

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...None.