textproduct: Newport/Morehead City

WHAT HAS CHANGED

Added areas of frost for portions of the coastal plain Tuesday night.

KEY MESSAGES

1) Strong cold front to impact the area today with scattered showers and thunderstorms

2) Areas of frost possible Tuesday night

3) Another frontal system to impact ENC late-week

Marine: Elevated winds and seas expected through Tuesday, with a period of gale-force winds expected for a portion of the waters tonight.

DISCUSSION

KEY MESSAGE 1...A pre-frontal trough (outflow from overnight storms to the north) has pushed south across the area this morning while the cold front is currently moving across the piedmont. Most of the showers from overnight convection to the north has dissipated before reaching NE NC with just a few showers pushing across the northern OBX early this afternoon. Expect shower and thunderstorm chances to increase this afternoon as instability has increased to around 500-1000J/Kg with around 40-50 kt of bulk shear in place and somewhat improving jet dynamics. The risk of severe weather continues to look low. The greatest risk looks to be strong downburst winds (40-45 mph) thanks to very steep low-level lapse rates. A reasonable worst case scenario is for a few 50-60 mph wind gusts to occur should stronger instability develop.

Behind the front, a much colder and drier airmass will move in on gusty northerly winds. Across the northern half of ENC, temperatures are expected to fall through the afternoon as the front moves through there first.

KEY MESSAGE 2...High pressure becomes centered over the Mid- Atlantic states Tuesday night bringing light/calm winds and initially good radiational cooling conditions with temperature dropping into the 30s by late Tuesday evening bringing a potential for frost development across the coastal plain. The one caveat that may may limit frost is that clouds are expected to increase through the overnight which could curtail radiational cooling. NBM has increased the probability of frost to around 50-75% across the coastal plain. NBM has lows inland in the mid 30s while MOS guidance is even colder with lows around 30-34. Given the growing season has begun for Eastern NC, felt it was prudent to add frost to the forecast. It is still a bit too early to issue a Frost Advisory and will let future shift evaluate the trends and the need for an advisory.

KEY MESSAGE 3...Another cold front is forecast to push south across the Carolinas late this week. 23/12z guidance is a bit slower with the front bringing the greatest potential for precipitation Friday night behind the front. While temps are forecast to be well above normal Friday, guidance currently keeps instability quite modest at less than 500J/kg and, with limited forcing and near zonal flow aloft, chances for prefrontal showers and thunderstorms appears to be minimal. A period of breezy northerly winds can be expected along and behind the front as well with a much colder airmass building in over the weekend.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Pred VFR conditions expected through the period. The cold front will continue to push through the terminals this evening. Shower and iso tstm chances now mainly east of the terminals, will push offshore in the next hour or two. High pressure builds in from the north and west tonight and Tuesday. N wind gusts around 20 kt tonight grad veering and becoming NE late tonight and Tue.

Outlook: There may be a risk of sub-VFR conditions Tuesday night into Wednesday night associated with a coastal trough that may develop offshore and attempt to migrate inland. Guidance is mixed on whether or not this trough will develop, though. If the trough does, indeed, develop, there would also be an accompanying risk of SHRA, especially along the coast. After mid-week, the next opportunity for sub-VFR conditions looks to be Friday or Saturday as another cold front moves in with SCT SHRA and TSRA.

MARINE

Currently seeing variable winds across the waters as a pre- frontal trough pushed into ENC this morning with N to NE winds around 15 kt or less north of Cape Hatteras and SW 15-20 kt south of Cape Hatteras, strongest over the offshore waters near the Gulf Stream. Seas are 2-4 ft northern waters and 4-6 ft southern/central waters.

A strong cold front will push across the waters late this afternoon and evening with a strong Nly post-frontal winds developing this evening. Scattered thunderstorms are expected to accompany the cold front, which may bring the possibility of enhanced wind gusts. Strong SCA conditions develop this evening over the northern waters and inland rivers and Gales, especially in gusts, across the Pamlico Sound and waters south of Oregon Inlet. Seas will build up to 6-9 ft behind the front, peaking late tonight. No changes to the Gale Warning or Small Craft Advisory area with only slight adjustment with the timing.

Outlook: High pressure builds in on Tuesday with winds and seas gradually laying down. Coastal troughing may develop mid-week, eventually leading to southerly winds returning as the trough moves inland. The next notable cold front is forecast to move through the ENC waters on Friday, with very similar impacts to today's front.

CLIMATE

Record High temps for 03/23 (Monday)

LOCATION TEMP/YEAR Morehead City 75/2012 (COOP - Not KMRH ASOS)

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...Small Craft Advisory until noon EDT Tuesday for AMZ131-230-231. Gale Warning until 5 AM EDT Tuesday for AMZ135. Small Craft Advisory until 11 AM EDT Tuesday for AMZ136-137. Small Craft Advisory until 11 PM EDT Tuesday for AMZ150. Gale Warning until 8 AM EDT Tuesday for AMZ152-154-156-158.