Key MESSAGE 1, A potent upper level shortwave will swing east through the Carolinas/Mid-Atlantic on Thursday, with an associated cold front passage Thursday morning. Ahead of this feature, strengthening southerly flow will develop associated with a notable southwesterly LLJ. This will support strengthening moisture transport, with PWATs climbing to 1-1.50", and dewpoints rising into the low-mid 60s.
Despite increasing moisture and instability, upper level ridging building into the area should keep a fairly tight lid on convective potential Wednesday and Wednesday night. Then, by the time the front reaches the area on Thursday, the timing looks less favorable for severe weather, primarily due to limited heating and weak instability. It should be noted, though, that this will be a high shear/low CAPE scenario that can sometimes support some stronger wind gusts or a very brief, weak tornado. While this risk appears low, machine learning guidance and pattern recognition suggests the risk isn't zero. The most likely scenario is widespread showers with a few embedded thunderstorms during the day Thursday.
Ahead of the front, breezy south winds and increasing low-level thicknesses beneath the ridge will support well above normal temperatures. The ECMWF's EFI guidance continues to show a very strong signal for above normal to record high temps. A few inland locations could approach 90 degrees. Very warm conditions continue into Wednesday night. In fact, lows Wednesday night will likely be warmer than our normal highs for this time of year.
KEY MESSAGE 2, Yet another strong cold front is forecast to move through the U.S. East Coast late this weekend or early next week. Similarly, strong southerly flow ahead of the front should support increasing moisture with 1"+ PWATs and 60+ dewpoints. This should once again allow a narrow ribbon of modest instability to develop in the warm sector. The timing of the cold front looks more favorably timed for peak heating/destabilization. Consequently, machine learning guidance show a slightly stronger signal for severe thunderstorms during this time. This is several days away, but something to monitor as we approach the weekend and early next week.
Temperatures will quickly rebound with increasing southerly flow ahead of the front this weekend. This looks to be followed by a notable surge of cold air next week. In fact, the Climate Prediction Center has highlighted a portion of our area for a risk of below normal temperatures. This may lead to frost/freeze potential which is notable because it comes after some greenup is ongoing during this recent stretch of above normal temps.
00z Wednesday through Sunday Light SW winds and VFR conditions through the TAF pd. Fog setup looks less significant than this morning, given lowered TD's this afternoon and temps expected to remain mainly above x-over threshold. Href only advertising a 20% chc of IFR for the inland areas. Any patchy fog that does develop should burn off by 14Z, leading to VFR conditions and breezy SW winds with a gust factor introduced after 15Z.
Outlook (Thursday through Sunday), Sub-VFR may return Thursday with scattered to numerous showers, isolated storms and gusty winds. Pred VFR to return Fri into the weekend.
Sea Fog: With the sounds now well into the 60s, the sea fog threat here has diminished substantially. Crystal Coast water temps have also warmed into the low 60s, so threat is marginal for some patchy fog. Best chc for some dense sea fg is the waters noth of C Hatteras, where sst's still in the 40s.
Light south winds of 5-10kt are expected to continue into early Wednesday morning, with seas of 2-3ft common. These low impact conditions won't last long, though, as winds and seas begin to build on Wednesday in advance of an approaching cold front. Ahead of the front, southerly winds of 10-20kt are expected, with seas building to 3-5ft. Behind the front, strong cold air advection and enhanced mixing is expected to support widespread 15-25kt winds, with frequent gusts of 30-35kt+. Of note, some guidance suggests gusts of 40kt possible. Given the recent warming of SSTs into the 60s, this seems very reasonable as this will help enhance mixing (compared to earlier this year when SSTs were much colder). In light of all of this, confidence continues to steadily increase regarding the potential for gale- force gusts, and a Gale Watch has been issued where confidence is the highest. Expansions of the watch will be possible, with additional marine headlines eventually needed. The cold front will be accompanied by a risk of thunderstorms on Thursday, the strongest of which may produce enhanced wind gusts and brief waterspouts.
Outlook: Winds and seas will lay down Friday and Saturday, with more benign marine impacts expected. Winds and seas will rebuild Sunday into Monday associated with the next strong cold front.
Nc, none. Marine, gale watch from Thursday morning through Thursday evening for amz150-152-154.
