textproduct: Newport/Morehead City

WHAT HAS CHANGED

Start time of SCA for southern waters (S of Ocracoke) has been delayed until 15Z Thursday.

Increased pops for Sunday into Monday.

KEY MESSAGES

1) A cold front will move through Thursday, bringing gusty winds with widespread showers (80-90%), along with a slight chance (20%) of embedded, non-severe storms.

2) High pressure will build in Friday and bring a brief round of dry conditions.

3) Another round of unsettled weather for this weekend into early next week as several low pressure systems and fronts move through the region bringing scattered to numerous (40-70%) coverage of showers, along with slight chance to chance (20-30%) of thunderstorms.

DISCUSSION

KEY MESSAGE 1...A positively tilted upper-level trough will move across the Midwest and Great Lakes region Thu. At the surface, a slow moving cold front will move into ENC, pushing S of the FA by Thu evening. Timing differences still in place across avail HiRes guidance due to development of weak lows and convective activity along and ahead of the front. Depending on the depth of these waves, FROPA could start as early as THU morning in the Nern FA, or delayed until the afternoon. These timing differences could have significant impacts on T/Td, Max temps, and available instability for storm development.

What is certain however, is that plentiful moisture along with mid to upper level lift is in place for widespread beneficial showers. There is a low, but non- zero, chance for some stronger storms to develop, but lapse rates are quite weak due to the widespread morning clouds and showers, and thus instability is in the form of long skinny CAPE's, which would yield some gusty winds even if no lightning is present. Have lowered thunder threat to slight chc (20%) across the FA as a result. Current QPF for 6Z THU-6Z FRI still ranges from 0.25-1" with highest totals over NWern half of the FA. In addition to showers and storms, Thursday will bring gusty SW winds with gusts to 20-25 mph inland and 25-35 mph along the coast. Convective showers and storms with greater vertical development, if some sunshine is realized, may mix down some of the stronger winds aloft, making strong convective wind gusts the greatest threat for the area.

KEY MESSAGE 2...Surface high pressure will briefly build in on Friday leading to a mild, mostly dry day with MaxTs in the low 70s (60s OBX). The high shifts offshore FRI night ahead of a shortwave to move through the Carolinas Saturday. This will lead to warmer, cloudier conditions to start the weekend with moisture advection ramping up in the Serly flow developing on the W side of the high.

KEY MESSAGE 3...Rain chances increased again steadily on the weekend, with the first wave on Sat with sheared mid level energy swinging through as weak warm front lifts north northeastward, producing chances for showers, then a better chance later SUN into MON with likely pop's ahead of another front and stronger wave of low pressure that is forecast to cross the FA. We will monitor this system for a strong to severe storm threat, as better dynamics are in place, with potentially more robust instability, which will depend on diurnal timing of mesoscale features.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

During the day today, a steady stream of mid-level moisture from the west should lead to a gradual increase in mid-level cloudcover. This will then be followed by a renewed surge of increasing low-level moisture this evening. This should support gradually lowering CIGs during that time, with CIGs potentially falling to MVFR conditions late tonight. Additionally, increasing large-scale lift should lead to a gradual increase in the risk of SHRA and TSRA, especially from KISO to KPGV. I added a PROB30 group for both of those sites to highlight the higher potential there compared to KOAJ and KEWN. I left TSRA out for now due to uncertainty with how much instability will be present.

Light southerly winds early this morning will give way to increasing winds during the day in a typical summer-like pattern with gusty winds along and behind the developing seabreeze.

Outlook: A cold front will slide south through ENC on Thursday with a continued risk of SHRA and TSRA. Additionally, there will be a risk of IFR CIGs (40-60% chance). A northerly wind shift will occur along the front. Drier air moving in behind the front should support improving aviation conditions by Friday. Looking ahead, the next opportunity for sub VFR conditions looks to be over the weekend. There will be a risk of TSRA over the weekend as well.

MARINE

SSW winds have inc due to inc diurnal thermal gradient, with speeds of generally 10-20 kt, with some gusts to 25 kt over the warmer Gulf waters. Choppy seas cont in the 2-4 ft@5-6sec range. Moderate to gusty SSW winds will continue as a slow moving cold front approaches and finally crosses from N to S during the day THU. Timing of the front will be slow, with the ctrl and srn waters esp south of Hatteras remaining in gusty swrly flow most of the day Thu, and thus the SCA will be in effect here, starting south of Ocracoke at 15Z Thu. Gusts of up to around 30 kt will be common, building seas to 5-7ft coastal waters, 7-9ft offshore waters. Showers and storms likely ahead of the front THU afternoon into early evening. Winds turn sharply N to NNE behind fropa on Thu, with a thump of winds to 25 kt or higher for a brief period on most sounds and nrn waters, but too brief to warrant issuance of any SCA's attm.

Outlook (Friday through Monday): Winds will decrease to 5-15 kt with gusts to 15-20 kt by Friday morning with good boating conditions returning by the afternoon as high pressure builds in. The improvement will be short lived with showers and storms expected again SAT, then again later Sun into Mon with troughing traveling over regional waters behind the high pressure sliding further offshore. SCA conditions on the nearshore waters poss late Sun into early Mon ahead of strong front, with brief gale gusts poss on the offshore waters.

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 5 AM EDT Friday for AMZ152-154. Small Craft Advisory from 11 AM Thursday to 2 AM EDT Friday for AMZ156-158.