textproduct: Newport/Morehead City

WHAT HAS CHANGED

Have added gale watches along all coastal waters and the Pamlico Sound out ahead of the next frontal passage. Have adjusted the start time of the ongoing small craft advisories.

KEY MESSAGES

1) Rain and thunderstorm chances increase Sunday afternoon and evening with a warm front lifting through the area late.

2) A strong cold front on Monday evening poses a risk of severe weather.

3) Return to chilly weather behind the front through mid-week. Mins at or below freezing Tue night/Wed morning.

Marine...Small craft conditions return tonight before potential gale force winds impact a portion of our waters on Monday.

DISCUSSION

KEY MESSAGE 1...A weak low pressure system will develop just off the FL/GA coast Sunday morning and gradually lift northwards with this low and its associated warm front reaching the Carolinas Sunday evening and pushing north of the area Sunday night. This will bring increasing chances for showers and thunderstorms to ENC starting as early as Sunday afternoon as light isentropic lift overspreads the area with showers and storms becoming more widespread overnight as the low and front near and track across ENC and forcing becomes maximized. This activity is then forecast to persist into Monday morning with the heaviest thunderstorms and rain amounts likely occuring along and east of Hwy 17. As the warm front lifts north, E'rly winds will veer to a SE and then S direction overnight Sunday allowing for warm moist air to overspread the region allowing for instability to advect into ENC Sun afternoon and evening. Latest HI-Res CAMs show MUCAPE values building to around 500-750 J/kg overnight Sunday. This combined with deep layer shear values around 25-35 kts and and with 0-1 km SRH values topping out around 100m2s2 the environment will be marginally favorable for a few isolated strong to severe thunderstorms especially near the coast overnight Sunday. Given the environment strongest storms would be capable of producing strong wind gusts and small hail, though an isolated tornado can't be ruled out either as any potential waterspout that develops across the coastal waters moves inland so conditions will need to be monitored for Sun night.

KEY MESSAGE 2...Not much change in the forecast since the previous update as an impressive upper level trough will dig across the Plains on Sunday and will become more negatively tilted as it moves east across the Mississippi River Valley on Monday. Latest forecasts suggests the potential for multiple rounds for showers and thunderstorms through the day with thunderstorm chances peaking with the FROPA Monday evening into Monday night. The environment will remain very favorable for strong to severe thunderstorms as instability builds with MLCAPE values between 500-1500 J/kg, deep layer shear values of 60+ kts, and SRH values increasing to 200+ m2s2 Mon afternoon. As a result, all severe weather hazards will be possible on Mon with damaging wind gusts and a few tornadoes being the more likely threat, while small hail being a lesser threat within the strongest storms.

The only proverbial fly in the ointment will be the amount of destabilization that takes place on Mon. Morning shower/thunderstorm activity and cloud cover could inhibit the amount of instability that builds across ENC on Mon, but even meager instability could still produce strong to severe thunderstorms given the strong shear and SRH values in place. Because of all this, SPC has outlooked the majority of ENC in an Enhanced risk (3/5) for severe weather, and AI NWP forecasts remain quite bullish on severe potential. The strong pressure gradient and stout LLJ ahead of the front will lead to a strong background wind-field. A wind advisory may be needed for areas along the Crystal Coast, Down East, and OBX MON evening into MON night.

KEY MESSAGE 3...A reinforcing cold front will cross ENC early Tue with cold high pressure filling behind it. The afternoon's CAA and the center of the high settling almost directly overhead late Tue night/early Wed will lead to clearing skies and calming winds. These conditions will prime the FA for strong radiational cooling effects, leading to MinTs AoB freezing for the majority of the mainland area, mid 30s OBX.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

VFR conditions expected to prevail at the terminals through most of the TAF period, with potential for sub-VFR and sct showers developing Sun afternoon and evening. Moisture increases late tonight with stcu beginning to push inland off the coastal waters. Light winds today, becoming gusty ESE Sun afternoon.

Outlook...The next frontal system will impact ENC through Monday bringing gusty winds and periods of sub-VFR conditions in showers and thunderstorms. Some thunderstorms may be strong to severe Monday. Pred VFR conditions will return by late Monday night and continuing through mid week.

MARINE

Light 5-10 kt SW'rly winds and 2-4 ft seas currently persist across our waters as a stalled front remains in place and high pressure remains off to the north and east. Winds will veer this afternoon and tonight to more of a Nerly direction this evening. This relaxing of winds and seas will be short lived with a warm front expected to lift Nward through area waters Sun and a strong cold front crossing from W to E late MON. Winds flip around to become Eerly 10-15kt this evening and will strengthen yet again becoming more Serly until the front crosses Mon night. Winds peak Mon night, 15-25G30kt over smaller inland waters, 20-30G35kt larger sounds, with strongest winds over GStream waters 30-35G40-45kt. Given the continued strong signal between deterministic and ensemble guidance have elected to hoist gale watches across all coastal waters and the Pamlico Sound starting on Mon with a small craft advisory becoming increasingly likely across the remainder of the waters starting on Mon as well. Showers and tstorms, some of which could be strong to severe, will be possible from Sun afternoon through Mon night until drier air arrives behind Mon night's front and Tue's reinforcing front.

Outlook: Winds become N-Nerly mid-week behind TUE's reinforcing front remaining generally 10-15G20kt through the remainder of the work week. Sea-driven SCAs likely to remain active into Wed morning, continuing to improve through late week.

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...Gale Watch from Monday afternoon through Monday evening for AMZ135. Small Craft Advisory from 2 PM Sunday to 5 PM EDT Monday for AMZ150. Gale Watch from Monday afternoon through Monday evening for AMZ150. Small Craft Advisory from 4 AM Sunday to 10 AM EDT Monday for AMZ152-154. Gale Watch from Monday morning through late Monday night for AMZ152-154-156-158. Small Craft Advisory from 10 AM Sunday to 10 AM EDT Monday for AMZ156-158.