textproduct: Newport/Morehead City

WHAT HAS CHANGED

Canceled active SCA for coastal waters from Oregon Inlet to Cape Hatteras, but had to extend the active SCA for coastal waters from Cape Hatteras to Hatteras Inlet for 3 more hrs. Continue to issue new marine headlines for the next FROPA event which will start late tonight and last into mid- week.

KEY MESSAGES

1) Rain and thunderstorm chances increase Sunday afternoon with a 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...A brief period of Small Craft Advisory conditions returns this evening/tonight.

DISCUSSION

KEY MESSAGE 1...An area of weak, developing low pressure will travel along or near the coast SUN. The low, starting off the FL east coast SUN morning, will reach the Carolinas SUN evening, pushing a pre-frontal surface trough and eventually a warm front through the area, bringing increased chances for showers and thunderstorms and backing low level winds. Rain will start light with isentropic lift increasing ahead of the front, becoming more vigorous along and behind the boundary in the afternoon and evening. Some of this more excited convection poses a non-zero chance for some damaging wind gusts with an isolated tornado. Chance of thunderstorms greatest along the Crystal Coast Nward across the OBX.

KEY MESSAGE 2...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. Chances for showers and thunderstorms will continue to increase through Monday and peak with the FROPA Monday night. This front will produce a strongly forced line of convection, and with ample deep layer shear and 0-3 km SRH, there remains potential for damaging wind gusts and tornadoes with a lesser risk for severe hail. Destabilization could be significantly inhibited due to cloud cover, showers, and thunderstorms associated with the pre- frontal surface trough SUN and SUN night, but even meager instability could still produce strong to severe thunderstorms with the FROPA given the 90-100kt of bulk shear. Non zero chance of prefrontal supercells developing ahead of the front MON with select HiRes guidance showcasing areas of 250-500 SRH, especially if greater clearing overnight SUN allows more instability to build ahead of the line. 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 /09Z SATURDAY THROUGH WEDNESDAY/

VFR conditions expected to prevail at the terminals through the TAF period. A system passing to the north is bringing a tightened pressure gradient across ENC overnight with light mixing persisting eliminating the fog threat for most areas. Gradients gradually relax through the rest of the overnight though and far southern rtes may decouple sufficiently to allow light fog to develop. HREF guidance shows a 20-40% chance of sub-VFR vsbys across southern Duplin/western Onslow Counties. In addition, a strong LLJ over NW rtes may bring minor LLWS concerns through around 09z.

Outlook...The next frontal system is expected to impact ENC Sunday through Monday bringing gusty winds and periods of sub-VFR conditions in showers and thunderstorms. Some thunderstorms may be strong to severe, especially on Monday.

MARINE

OBs currently showing WSWerly winds 10-20kt across almost all waters save for 15-20G25-30kt winds over GStream waters. Seas generally 3-4ft@5-6sec. The bane of the overnight forecast has been the GStream waters S of Cape Hatt around Diamond Shoals where the obs continue to show winds 20-25G30kt. Winds here have outperformed all available guidance through the entire overnight period. Even though the deterministic models are all underdone, they general consensus is winds come down through the morning. I have extended the active SCA for the zone covering Diamond Shoals (Cape Hatt to Hatt Inlet) up to 0900est. Conditions briefly improve today as high pressure traverses regional waters behind weak front with winds weakening as they veer to more Nerly mid- day and early afternoon. 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. 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. Should the trends in guidance and the current forecast hold, Gale watches will likely be needed for the strongest winds ahead of MON night's FROPA. Have begun issuing the SCAs for coastal waters not currently under any headlines with SCA criteria winds reentering Sern-most coastal waters by 0600est SUN.

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...Small Craft Advisory from 2 PM Sunday to 6 AM EDT Wednesday for AMZ150. Small Craft Advisory from 11 PM this evening to 6 AM EDT Wednesday for AMZ152. Small Craft Advisory until 9 AM EDT this morning for AMZ154. Small Craft Advisory from 6 AM Sunday to 6 AM EDT Wednesday for AMZ156-158.