textproduct: Newport/Morehead City

WHAT HAS CHANGED

The Small Craft Advisory from Ocracoke Inlet south through Surf City has been expanded through Wednesday night.

KEY MESSAGES

1) Warmer air will precede a cold front that will track across the area bringing a quick round of rain during the day Wednesday.

2) Low pressure is forecast to pass over, or just south of, the area this weekend bringing another round of rain and potentially a few thunderstorms.

AVIATION...A period of low level wind shear will be possible overnight tonight at all TAF sites ahead of a frontal system that will affect the area on Wednesday.

MARINE...Increased risk of hazardous conditions for small craft this evening through Wednesday night.

Monitoring potential for dense marine fog across portions of our inland waters through Wednesday.

DISCUSSION

KEY MESSAGE 1...Weak to moderate WAA within a southwest flow pattern has allowed temperatures to warm into the mid to upper 60s inland this afternoon. As of 1pm, SW portions of ENC were flirting with 70 degrees, which is quite the change from the past few weeks. Closer to the coast, the cold shelf waters are helping to hold temperatures in the 50s. Southwesterly flow will continue through about early afternoon Wednesday in advance of an approaching cold front. This will keep temperatures on the warmer side (compared to recent weeks). Highs on Wednesday may not get quite as warm as today, mainly due to increased cloudcover and an increasing chance of rain. CAA doesn't look particularly strong behind Wednesday's front, and temperatures may actually rise slightly just behind the front before falling in the evening.

Increasing low-mid level moisture and modest lift along the advancing frontal zone should support several hours of light to moderate rain during the day Wednesday, especially during the morning and early afternoon hours. Given the progressive nature of the system, rainfall amounts should be light (0.10-0.20").

KEY MESSAGE 2...Medium range guidance are in decent agreement bringing a progressive shortwave trough, and an accompanying surface low, east across the Southeast U.S. this weekend. Guidance has been flipping back and forth between a more amplified and further inland track vs a weaker, more suppressed southern track. The latest suite of 06z/12z guidance has shifted back towards a more suppressed/weaker/southern track. Despite the trend towards a more southern track, it currently doesn't appear that there would be enough cold air in place for any wintry precipitation. That said, a more southern track would certainly favor colder temperatures, just not cold enough for wintry precip. A more southern track would also tend to lower the risk of thunderstorms. We'll continue to see how model trends evolve, but for now the trend favors a cold rain with a lower risk of thunderstorms late Saturday through Sunday night.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

VFR conditions prevail this evening across all terminals with light south to southwesterly winds as high pressure sits just east of the Bahamas and a cold front works its way across the Midwest and over the Appalachians. Despite cool SSTs and elevated Tds sea fog has yet to materialize, and odds of impacts to coastal terminals along the Crystal Coast and OBX are falling with this forecast. Odds for shallow fog remain low tonight, decreasing further into Wed morning as southwesterly flow increases. If any fog was to develop it would be from now to around 03z when winds will be at their calmest and skies clearest.

There will likely be a period overnight tonight into Wednesday morning where low level wind shear could be a possibility of 30-40 kts near 2000 feet with strengthening LLJ ahead of the approaching cold front.

Guidance still favors rain chances tomorrow ahead of the approaching cold front, resulting in cigs dropping to at least MVFR Wednesday morning through 18-20z. Odds of IFR are moderate (around 30-40%) and most favored for terminals south of ISO-OCW, although these will likely be temporary. All terminals will return to VFR prior to 00z as cooler and drier air sweeps in behind the front.

Outlook: VFR expected to prevail until later in the weekend when a low pressure system moving across the southern CONUS combines with a weak low forming off of the coast to bring some more unsettled weather to the area.

MARINE

South to southwest winds of 5-15kt this afternoon are forecast to steadily build to 10-20kt by tonight. A strong marine inversion over the coldest waters should keep mixing at a minimum. Over the warmest waters, there should be enough mixing to support gusts of 20-30kt. Over those waters is where conditions will be the most adverse for small craft. Of note, it was decided to hold onto the Small Craft Advisory for the Pamlico Sound, but in reality, the risk of 25kt winds should be confined mainly to the far southern extent of the sound. For the coastal waters, seas of 4-8ft are expected tonight into early Wednesday in the pre-frontal southwesterly flow. Of note, warm and moistening southwest flow overtop the cold shelf waters may support a risk of sea fog development this evening into Wednesday morning. Local sea fog research suggests a more marginal risk, mainly due to higher air temp/water temp differences. We'll continue to closely monitor this potential, though.

A cold front moves through Wednesday, with winds shifting around to northerly. Somewhat deeper mixing behind the front should lead to a renewed risk of 25kt winds for a larger portion of the area. Since there isn't much downtime with winds across the southern waters, the Small Craft Advisory was extended out in time through Wednesday night. This will now cover both the pre- frontal and the post-frontal risk of 25kt winds. For the central waters, it appears that there will be a longer time of sub-25kt winds, and it was decided to hold off on extending the advisory there. What will likely happen is that another advisory will need to be issued to cover the post-frontal winds for both the central and northern waters. For the coastal waters, seas of 3-6 ft are expected in the wake of the cold front.

Outlook: Low pressure is forecast to track east across the Southeast U.S. this weekend, emerging off the coast Sunday or Sunday night. Guidance continues to differ on the strength and track of this low. In general, confidence is moderate to high regarding the potential for 25kt winds, but low regarding something stronger.

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...Small Craft Advisory until 7 AM EST Wednesday for AMZ135. Small Craft Advisory until 4 PM EST Wednesday for AMZ152-154. Small Craft Advisory until 7 AM EST Thursday for AMZ156-158.