textproduct: Newport/Morehead City

WHAT HAS CHANGED

Confidence has increased in severe weather potential for FROPA MON. Have added severe tstorm wording to Wx Grids from late MON morning into the first half of MON night.

Strengthening onshore flow today and then even stronger Serly flow on MON has prompted the issuance of a high surf advisory for Eastern Carteret through Ocracoke and Hatteras Islands from this afternoon into Monday night.

Have converted most of the active gale watches to warnings as well as added SCAs for smaller inside waters.

KEY MESSAGES

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

2) A strong cold front MON evening brings strengthening winds and chance of severe thunderstorms.

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

Marine...Small craft conditions in place through SUN with gale force winds impacting coastal waters and Pamlico Sound MON.

DISCUSSION

KEY MESSAGE 1...A weak low pressure system will develop just off the FL/GA coast this morning and gradually lift Nward with this low and its associated warm front reaching the Carolinas this evening and reaching the VA border tonight. This will bring increasing chances for showers and thunderstorms and strengthening onshore flow starting this afternoon. This morning, light isentropic lift overspreads the area leading to the potential for some light rain across portions of the Inner Banks and Crystal Coast early. Showers and storms becoming more widespread second half of the day as the low and front near and track across ENC, warm sectoring the FA and increasing dynamic forcing. As the warm front lifts Nward, Eerly winds will veer to a SEerly and eventually Serly overnight, allowing for warm moist air to overspread the region, increasing instability. HiRes CAMs continue to show MUCAPE values building to ~500-750 J/kg overnight. This, combined with deep layer shear values around 25-35 kts and 0-1km SRH values ~100m2s2, the environment will be marginally favorable for a few isolated strong to severe thunderstorms, especially near the coast overnight. Strongest storms could be capable of producing damaging wind gusts and perhaps small hail, though an isolated tornado can't be ruled out either as any potential waterspout that develops across the coastal waters could reach the coast and move inland. The strengthening onshore flow this afternoon and evening will rapidly build seas, leading to the issuance of a high surf advisory. Beaches susceptible to a SEerly wave direction could be at risk for wave runup issues and maybe ocean overwash for particularly vulnerable locations.

KEY MESSAGE 2...Impressive upper level trough will dig across the Plains on today, becoming more negatively tilted as it moves Eward across the MS River Valley tomorrow. Latest forecasts suggests the potential for multiple rounds of showers and thunderstorms through the day. First, prefrontal SFC trough sharpens early as LLJ strengthens, opening the door for organized convection starting early MON morning. 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. Prefrontal supercells are not out of the realm of possibility, with any cells with even moderate vertical development capable of bringing the stout winds aloft down to the SFC. Damaging wind gusts and a few tornadoes being the most likely threat, while small hail being a lesser threat within the strongest storms. The second round of precip will be an organized line of showers and thunderstorms expected with the front MON evening into MON night. This line will lead to the potential for more damaging winds and a QLCS tor threat.

Morning shower/tstorm activity and cloud cover could inhibit the amount of instability that builds across the FA Mon, but even meager instability could still produce strong to severe tstorms given the strong dynamics in place. Because of all this, SPC has outlooked all of ENC in an Enhanced risk (3/5) for severe weather with a a Moderate (4/5) risk just to our W from SC Nward into VA, where the greatest chance dynamics will coincide with peak heating, and therefore greatest chance for higher instability values to feed storms and potential supercell development. 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. High Surf Advisory remains in effect through MON with beach erosion and ocean overwash remaining a concern for vulnerable locations susceptible to Serly wave directions.

KEY MESSAGE 3...The initial blast of CAA directly behind MON's FROPA will lead to MinTs approaching freezing across the Coastal Plain. A second 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 in the upper 20s for the majority of the mainland area, mid to upper 30s DownEast and OBX.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

VFR conditions currently with sct-bkn STCU advecting across rtes with bases are around 4k ft. A better chance for sub-VFR cigs (up to 70-90%) develops this afternoon and evening as a warm front lifts across the area bringing scattered showers and thunderstorms. Instability and shear increases this afternoon and tonight and could see isolated storms producing damaging wind gust or a brief tornado. SPC has the region in a marginal risk (level 1/5) for severe storms late today and tonight. Could see a period of VFR conditions develop after midnight but expect sub-VFR conditions return Monday morning.

Light Ely winds this morning will become SE and increase to around 10-15 kt with gusts around 20-25 kt late this morning and afternoon. Winds become Sly around 10-25 kt this evening and will see LLWS concerns develop this evening as a strong low level jet develops ahead of an approaching cold front.

Outlook...A strong frontal system will impact ENC Monday bringing gusty winds and periods of sub-VFR conditions in showers and thunderstorms. Thunderstorms may be strong to severe with SPC placing ENC in an enhanced risk (level 3/5) of severe thunderstorms with a moderate risk (level 4/5) across the piedmont and western coastal plain. Thunderstorms will have the capability of producing damaging wind gusts, isolated strong tornadoes and large hail.

Pred VFR conditions will return by late Monday night and continuing through mid week.

MARINE

ESEerly winds currently 15-20kt offshore, 10-15kt inside, with seas generally 2-3ft@4-6sec. These winds strengthen through the morning as a warm front approaches from the S and lifts Nward through area waters this afternoon and evening. A strong cold front crosses from W to E late MON/early TUE. Winds gradually veer to become more SEerly while strengthening through the day. Winds peak Mon night, 15-25G30kt over smaller inland waters, 20-30G35kt larger sounds, with strongest winds over GStream waters 30-35G40-45kt. Have upgraded all but one gale watch to gale warnings starting MON, with a SCA conditions expected across all coastal waters through the day today. The lone gale watch remains over Nern coastal waters, where gale force gust potential is more marginal. Given the onset is later in the day MON, opted to keep the watch here to give dayshift another cut at the wind forecast today. Remaining inland rivers and sounds have had SCAs introduced for the strengthening Serly flow ahead of FROPA late MON. Showers and tstorms, some of which could be strong to severe, will be possible from this afternoon through Mon night until drier air arrives behind Mon night's front and Tue's reinforcing front. Waterspout threat in place for cells along and near the warm front lifting forward this afternoon and evening. Supercell potential increases overnight tonight and into MON, increasing risk of waterspouts. Any of MON's storms with even modest vertical development could bring strong winds aloft down to the SFC. Strongest cells could also produce small hail.

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. Low pressure system well offshore lateweek expected to increase swell and could further the need for extending SCAs that follow the Gales MON and TUE.

MHX WATCHES/WARNINGS/ADVISORIES

NC...High Surf Advisory from 4 PM this afternoon to 2 AM EDT Tuesday for NCZ196-204-205. MARINE...Small Craft Advisory from 11 AM Monday to 11 AM EDT Tuesday for AMZ131-230-231. Gale Warning from 2 PM Monday to 2 AM EDT Tuesday for AMZ135. Small Craft Advisory from 2 PM Monday to 11 AM EDT Tuesday for AMZ136-137. Small Craft Advisory from 2 PM this afternoon to 5 PM EDT Monday for AMZ150. Gale Watch from Monday afternoon through Monday evening for AMZ150. Small Craft Advisory until 6 AM EDT Monday for AMZ152-154. Gale Warning from 6 AM Monday to 2 AM EDT Tuesday for AMZ152- 154. Small Craft Advisory until 10 AM EDT Monday for AMZ156-158. Gale Warning from 10 AM Monday to 4 AM EDT Tuesday for AMZ156- 158.