Key MESSAGE 1, Thunderstorm activity from last night has since weakened with just some isolated showers noted across ENC this morning. Latest surface analysis shows this ongoing activity is currently riding east just to the south of a slow moving cold front which is noted near the NC/VA border. General expectation is for this front to gradually move south through the day eventually stalling and washing out across ENC, bisecting the area around or just north of Hwy 70 this afternoon. This backdoor cold front will combine with the seabreeze and will be the focus for shower and thunderstorm development later this morning and afternoon. While CAM guidance has come in slightly drier than previous runs, I am a bit skeptical of this outcome given the poor performance of the CAMs over the last few days. For now to not completely rule it out, have lowered PoPs slightly closer to 40-60% to lend credence to the potential scattered nature of activity. But will note, synoptically it would make sense to have more precip coverage today as compared to yesterday, so wont be shocked if I am slightly too low on PoPs and adjustments upwards are needed later this morning.
To the south of this front a warm and unstable airmass will be in place outside of the N'rn OBX and far NE'rn counties as the front will move through these locations first. A combination of ample moisture and hot temps today will result in MLCAPE building during peak heating to around 2000-3000 J/kg across ENC with the highest values noted along the Crystal Coast and just south of the aforementioned front. Will note some guidance has MLCAPE values building closer to 3000+ J/kg this afternoon which could act to increase thunderstorm strength. In addition to this, with the front moving south we may have slightly more deep layer shear as compared to previous days (closer to 25kts). All of this could lead to a few storms becoming strong to severe in nature this afternoon. Spc has portions of ENC under a marginal risk (level 1/5) for severe weather with damaging winds (40-60 mph) and small hail being the main hazard within the strongest storms.
In addition to this, given the slow moving nature of the front, storm motions will be rather slow, and with PWATs generally around 2-2.5 inches across the region any thunderstorm that develops will be a rather efficient rainmaker. So in addition to the severe threat we will also have a threat for localized flash flooding, and WPC has kept much of the area under a marginal risk for excessive rainfall as well.
Beyond today, PoPs return back to climo (20-40%) as more typical seabreeze showers/storms return. Hts/thicknesses slowly build in the process as ridging begins to build once again, with heat indices around 100-110 in the forecast later this week. As we get into the weekend, an upper trough and associated surface front look to approach from the north and west bringing the next threat for increased shower and thunderstorm activity
KEY MESSAGE 2, While we sound like a broken record, we will continue to be hot and humid across ENC into this weekend. Today the hottest temps (upper 80s to mid 90s) will be noted south of the previously mentioned cold front today. While cooler temps (low to mid 80s) will be noted along the OBX which is where the front will move through first. Combined with dewpoints in the 70s we will once again see heat indices today around the 100-110F range across the Crystal Coast. As a result have issued a heat advisory for the same area as yesterday as areas from Greene/Pamlico County south have the best chance to reach heat advisory criteria given later timing for showers and storms here. This also coincides with the major heat risk footprint across the CWA.
As we get into Thursday and into this weekend expect to see continued hot and humid conditions as temps get into the 90s each day with the hottest temps occuring on Thurs/Fri. Lows each night only get into the mid 70s to low 80s not bringing much relief to the area each night. With dewpoints in the 70s there could be widespread heat indices around 100-110 each afternoon from Thurs into Sat. Probabilistic heat risk shows a 60% + chance for reaching major heat risk values with the greatest risk coming on Thurs/Fri so additional more widespread heat advisories may come into play over the next few days before we finally cool off Sun/early next week.
KEY MESSAGE 3, Some changes with regards to this weekend as instability has trended down with MLCAPE values likely closer to 1000-2000 J/kg this weekend as more cloud cover may be noted this weekend. Either way, with an upper level trough, mid level shortwave and surface front approaching from the north and west this weekend an increase in shower and thunderstorm chances is likely. While instability has trended down, with a cold front moving into the area from the north and west could see a few stronger storms this weekend.
12z Wednesday through Sunday A mix of low stratus and patchy fog has developed across portions of inland ENC this morning with low stratus and thunderstorms noted along the OBX near Hatteras. Expect any leftover low stratus and fog to dissipate within the next hour or two across ENC. Have put TEMPO groups in for reduced ceilings/vis until 13Z to account for this. Afterwards expect widespread VFR conditions outside of the OBX where patchy areas of sub-VFR conditions will continue as isolated to widely scattered showers and thunderstorms impact the area. As we get into the late morning and afternoon, a cold front will begin to approach from the north which will bring yest another round of TSRA to portions of ENC. Any thunderstorm that impacts the area would bring a threat for brief periods of sub-VFR ceilings/vis mainly after 18Z. For now given the scattered nature of this activity have just used VCTS and PROB30 groups at the terminals to account for this threat. Otherwise once the front stalls and washes out this evening will likely see a return to VFR conditions to all of ENC.
Outlook (Thursday through Sunday): Beyond Wed, more typical iso to widely sct activity expected as ridging rebuilds into ENC so a much lower threat for sub-VFR conditions. However, as we get into the weekend as an upper level trough and associated surface front approaches increasing chances for showers and storms as well as sub-VFR conditions will be noted.
Have issued a small craft advisory along the coastal waters from Hatteras Island south to Onslow Bay as latest obs have shown frequent SW'rly wind gusts up to 25 kts overnight. While this small craft advisory currently goes out until 8AM today, have seen a recent reduction in wind gusts so could end this small craft earlier than previously anticipated.
Either way, latest obs across our waters show widespread 10-20 kt SW'rly winds with a few gusts up to 25 kts across our waters this morning. With a weak backdoor cold front approaching from the north, expect the gradient to weaken across our waters today allowing winds to ease to 5-15 kts by this afternoon. Winds will shift to a NE-ENE direction to the north of the front and remain SW'rly to the south of the front. The front is forecast to bisect our waters around Hatteras Island before washing out this evening. In addition to the weak wind shift, scattered showers and thunderstorm will be possible today along this front bringing a risk for locally enhanced winds and seas. As we get into tonight, front dissipates ending the thunderstorm threat and allowing winds to become S'rly across all waters varying from SE-SW at 5-15 kts. Seas generally remain around 2-5 ft into Tuesday morning across our coastal waters.
Outlook (Thursday through Sunday): A summer time pattern with a strengthening thermal trough is forecast from Thurs on into this weekend. This will result in increasing SW'rly winds each afternoon through Sat bringing our next threat for small craft conditions to our waters. Next frontal passage occurs over the weekend as well brining increased chances or showers and thunderstorms Sat night into Sun.
Nc, heat advisory from 11 am this morning to 8 pm EDT this evening for ncz079-090>092-094-193>196-198-199. Marine, none.
