textproduct: Newport/Morehead City

WHAT HAS CHANGED

No significant forecast changes.

KEY MESSAGES

1) Dangerous heat builds through the week and into the weekend

2) Unsettled pattern expected to return by this weekend, including the next risk of strong to marginally severe thunderstorms

DISCUSSION

KEY MESSAGE 1...Mid-level ridging will overspread the Carolinas over the next couple of days with warming low-level thicknesses beneath it. Additionally, persistent southerly flow begins today, potentially lasting all the way into next week. Ridging plus much drier conditions aloft should put a cap on convection over the next couple of days, and will probably limit cloudcover as well. Strong heating plus all of the factors above should support highs rising into the mid to upper 90s inland, and around 90 along the coast.

With the dry airmass in place, dewpoints are expected to mix out into the 60s inland through at least Thursday. While it will be hot, the drier airmass should keep heat indices close to the actual air temperatures, lowering the risk of 105+ heat indices. This should especially be the case today and Thursday. Although, Thursday may come close to Heat Advisory criteria, especially just inland of the coast where rising dewpoints along the seabreeze may support a 2-3 hour period of heat indices near 105.

From Friday on, dewpoints are expected to steadily increase with continued, and moistening, southerly flow. This should lead to dewpoints consistently staying in the 70s, even during peak heating/mixing. It's at this point that the risk of heat indices of 105-110 degrees is expected to increase, and is when heat headlines are most likely. Afternoon convection and increased cloudcover may eventually factor in regarding headlines vs no headlines Sunday into Monday, but it will also be more humid by then.

KEY MESSAGE 2...Low-mid level troughing is forecast to setup across the Eastern U.S. over the weekend and into next week. Increasing moisture and instability, plus increasing low-level forcing, is expected to support a more active convective period. Initially, convection is expected to be primarily focused along the seabreeze Friday and Saturday, and will probably be more isolated in nature. An increasing coverage is then expected Sunday into Monday. Deep layer shear is forecast to be weak (<25kt), but moderate to strong instability should support a daily risk of strong to marginally severe pulse-type convection. There is strong support for this in analog and machine learning guidance, especially Sunday-Tuesday.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

The main aviation forecast challenge, and potential impact, early this morning is BR/MIFG/FG. Observations have bounced in and out of LIFR conditions for much of the night, but webcams show this is mostly due to shallow, lower-impact, fog. Any sub- VFR conditions should quickly improve to VFR by 13z. Dry conditions are expected today, with no TSRA risk. Of note, the afternoon seabreeze is expected to move through KOAJ and KEWN between 19-21z with a bump up in south to southeast winds. Another round of BR/MIFG/FG may develop tonight with periods of sub-VFR conditions.

Outlook (Thursday through Sunday): VFR conditions are anticipated to prevail through Thursday along with a reduced risk of TSRA. On Friday, isolated seabreeze TSRA will be possible. This is expected to be followed by an increasing risk of TSRA impacts over the weekend.

MARINE

Light and variable winds this morning are expected to become southerly by this afternoon and steadily build through the evening hours. Despite the building winds later today, seas are forecast to hold in the 2-3ft range through tonight. No thunderstorms are expected through tonight.

Outlook (Thursday through Sunday): Southerly winds will continue to build through the weekend, peaking at 15-25kt by Saturday, then remaining around that range into next week. Seas will respond and build to 3-5ft by Saturday, then peak in the 4-7ft range by Sunday. The risk of thunderstorms is expected to increase over the weekend, especially on Sunday.

MHX WATCHES/WARNINGS/ADVISORIES

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