Key MESSAGE 1, Anomalously warm low-level thicknesses beneath anomalous ridging aloft has allowed temperatures to reach the low to mid 90s as of this afternoon. The one exception is along the OBX where an onshore flow is keeping temperatures in the upper 80s. Meanwhile, dewpoints in the mid 70s is supporting heat indices of 105-110 degrees away from the coast. The setup remains mostly unchanged on Thursday, and another Heat Advisory has been issued for most of ENC for then. The one difference on Thursday is that a stronger southerly onshore flow and stronger seabreeze is expected along and just inland of the Crystal Coast. It's expected that this will hold temperatures down just enough to keep coastal Onslow County and most of Carteret County below Heat Advisory Criteria. In light of this, those area will be excluded from tomorrow's advisory.
Friday continues to have the strongest signal for the peak of this week's heat wave, with highs approaching 100 degrees across the coastal plain, and low to mid 90s along the coast. Even with another strong seabreeze and southerly onshore flow, it should get hot enough to reach Heat Advisory criteria even along the coast. Of note, some inland locations may flirt with Extreme Heat Warning criteria. Regardless, this will continue to be a notable, and unusual, late-season heat wave for all of enc.
KEY MESSAGE 2, A strong upper level trough will develop off the U.S. East Coast over the weekend, and this will help drive a strong cold front south through the Carolinas on Saturday. Strong heating of a moist boundary layer ahead of the front should allow moderate to potentially strong instability to develop from the Mid-Atlantic south into North Carolina on Friday. While some residual subsidence/capping may be present beneath the ridge, especially across NC, guidance show a decent signal for convection developing upstream of ENC, and making a run towards the coast during the evening or overnight hours. While the pattern is supportive of severe weather, the timing is less favorable for ENC, and there is added uncertainty regarding any residual influence of the ridge. Consequently, machine learning guidance have actually backed off some on the severe weather potential on Friday, which lowers overall confidence.
On Saturday, the ridge will continue to get suppressed further south and west with less influence across the Carolinas. This plus increased forcing along the cold front should support an improved risk of deep convection, and less limiting factors, compared to Friday. Interestingly, machine learning guidance has pulled back some on Saturday as well, and this may be related to some uncertainty regarding the timing of the front and how much instability can develop along/ahead of it. Of the two days, though, Saturday appears to have a better chance than Friday. We'll continue to monitor the potential over both days. In general, the setup favors clusters of thunderstorms, perhaps an MCS or two, impacting the area with strong to damaging wind gusts.
Behind the front, temperatures and humidity will get knocked back down closer to normal for early September, with more comfortable conditions lasting into early next week.
18z Wednesday through Monday Forecast confidence is high over the next 24 hours.
Once again, scattered cumulus are developing with the heating of the day, especially from KISO to KFFA where a weak boundary is leading to an area of better lift. Along this area, an isolated SHRA or TSRA appears possible, but confidence is too low to include a PROB30 mention at KISO or KPGV. Skies should clear out tonight and, with light winds, this may allow a period of reduced VIS in BR/MIFG. Probabilistic guidance doesn't show much of a signal, but I opted to keep a mention in the TAFs to keep consistent with the previous forecast. Thursday should be a repeat of today's conditions, with afternoon cumulus and VFR conditions.
NOTE: AMD NOT SKED has been appended to the EWN TAFs as the site is not transmitting through normal channels. The site is still reporting via telephone so it will be monitored, but not as frequently as when it is completely operational. The next closest ASOS is at Cherry Point (KNKT).
Outlook: The risk of TSRA is likely to increase late Friday into Saturday as a cold front moves through the area. Confidence is moderate regarding the timing of the greatest TSRA risk. For now, the latest guidance shows the strongest signal on Saturday. Sub-VFR conditions will be possible with any TSRA during this time. Behind the front, a northeasterly wind shift will occur, with northeasterly flow continuing into early next week.
Southeasterly long-period swell (2-3ft at 10-11s) from the remnants of "Dolly" will continue to impact the coastal waters through this evening. Seas may briefly lay down overnight, then build again on Thursday as a strengthening thermal gradient supports building south to southwest winds. Those winds are expected to peak Thursday afternoon into Thursday night at 10-20kt. The risk of thunderstorms is expected to remain LOW (<10% chance) through Thursday night.
Outlook: A strong thermal gradient will continue to support moderate southwesterly winds of 10-20kt Friday and Friday night. A cold front will then move through on Saturday with a northeasterly wind shift. Winds are expected to remain moderate through Monday, then lay down as high pressure builds in on Tuesday.
Nc, heat advisory until 8 pm EDT this evening for ncz029-044>047- 079>081-090>092-094-193>196-198-199. Heat advisory from 11 am to 8 pm EDT Thursday for ncz029- 044>047-079>081-090>092-094-193-194-198. Marine, none.
