textproduct: Newport/Morehead City

WHAT HAS CHANGED

Heat Advisory issued for most of eastern NC this morning.

Adjusted PoPs down slightly this afternoon given uncertainty in thunderstorm coverage along the seabreeze.

KEY MESSAGES

1) Marginal to slight risk of severe thunderstorms expected this afternoon into the evening. Unsettled weather pattern lingers into late week.

2) Heat Advisory reissued for all but coastal areas this afternoon. Dangerous heat likely to return late week.

DISCUSSION

KEY MESSAGE 1... Only change made for the remainder of todays forecast was to lower PoPs along the seabreeze to SChc to Chc as guidance overnight and into this morning has depicted lower coverage than previously forecast. The overall trend calls for isolated to widely scattered showers and storms this afternoon along the seabreeze with the potential for more thunderstorm activity tonight with the approach of a cold front.

Latest surface analysis depicting yesterday's stalled frontal boundary roughly draped from the southern Pamlico Sound westward but becoming increasingly diffuse. Well to our west is a stronger cold front stretching from the Great Lakes into the southern plains ahead of an advancing s/w trough over the upper Midwest, expected to progress eastward later today.

Airmass over the southeastern CONUS will be recovering today as remnant frontal boundary lifts northward and southwesterly flow increases ahead of the approaching front. With highs reaching back well into the 90s and Tds still sitting in the upper 60s to low 70s strong instability will be present this afternoon with mean surface CAPE climbing above 1500-2000 J/kg and high-end scenarios depicting values north of 3000 J/kg. Shear, however, will be relatively weak with less than 20 kt across the southern half of the state and around 20-25 kt to the north. This is an environment that would support somewhat organized storms, with the stronger cells capable primarily of damaging wind gusts.

Trickiest part of the forecast is initiation and timing. Most guidance is not very bullish on the seabreeze being a focus for development on the 00z suite, instead favoring development to our west along a pre-frontal trough progressing across the state with further downstream development off of resulting outflow. The HRRR has been particularly aggressive on this, showing more robust convection arriving until after 6-7 PM across the inner coastal plain. Our forecast shows PoPs increasing after the 2-3 PM range, with the expectation of at least isolated development along the seabreeze. Airmass remains unstable through the evening hours and expect a continued risk of showers and thunderstorms to progress eastward after nightfall with threat potentially not moving fully offshore until after 2 AM Monday.

Beyond today, overall pattern through the week remains at least marginally conducive for shower and thunderstorm threats each afternoon and evening. The next best chance for stronger storms appears to be Thursday into Friday ahead of a stronger front where deeper shear will likely be present with equally strong instability.

KEY MESSAGE 2...With delayed convective initiation forecast, heat and humidity will hang on for the better part of the day allowing heat indices to once again climb north of 105 late this morning and lasting well into the afternoon. Risk of dangerous heat is more expansive today than yesterday with the frontal boundary no longer in the picture, and issued a Heat Advisory for all but coastal areas. Current advisory goes until 00z, but this may be cancelled early depending on convective trends.

Once the first front passes on Monday, a relatively cooler couple of days are likely. Heat and humidity will likely return again on Thursday and Friday ahead of the late-week front with more widespread heat index values of 105-110 forecast.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

VFR conditions across the terminals early this afternoon. Winds become gusty this afternoon before isolated to scattered showers and thunderstorms develop over the area. Sct storms likely along the sea breeze this afternoon with potential for more robust convection likely to enter from the west later this afternoon and evening, potentially impacting terminals through 03-04z. A few storms could be strong with damaging gusts exceeding 40 kt along with tempo sub-VFR. Behind the convection, another pre- dawn bank of low stratus could develop inland. Fog appears less likely overnight with winds unlikely to decouple.

Outlook: Front clears area later Monday although iso to sct shower and thunderstorm risk will extend into Tuesday and Wednesday. More widespread convective threat returns Thursday into Friday with stronger front. Overnight fog and stratus threat possible each morning.

MARINE

Little change in marine headlines this morning. Forecast calls for increasing southwesterly winds ahead of approaching cold front expected to cross area waters on Monday. Highest confidence in said conditions is across offshore waters and Pamlico Sound with gusts to 30 kt, with gusts up to 25 kt possible across inland rivers and adjacent sounds. Outside of SCA conditions, there will be a renewed risk of showers and thunderstorms especially after nightfall as more organized convection inland migrates over area waters after 00z. Environment will be favorable for a few stronger storms with gusts in excess of 40 kt.

Outlook (Mon 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 a low risk of Gales across the outer waters.

MHX WATCHES/WARNINGS/ADVISORIES

NC...Heat Advisory until 8 PM EDT this evening for NCZ029-044>047- 079>081-090>092-094-193-194-198-199. Beach Hazards Statement until 8 PM EDT this evening for NCZ195- 196-199-204-205. MARINE...Small Craft Advisory until 8 AM EDT Monday for AMZ135. Small Craft Advisory from 4 PM this afternoon to 3 AM EDT Monday for AMZ137-231. Small Craft Advisory from 6 PM this evening to 5 AM EDT Monday for AMZ150. Small Craft Advisory until 11 AM EDT Monday for AMZ152-154-156- 158.