Key MESSAGE 1, Warm and muggy this morning is the name of the game with temps only getting down into the 70s to low 80s. A rather similar setup across ENC for today as compared to yesterday as weak upper ridging centered off the GA/FL coast extends N towards ENC keeping the area under a hot airmass. Temps across inland areas get into the mid 90s while temps along the OBX get into the upper 80s this afternoon. At the same time, expect dewpoints to remain around 75-80 with the highest dewpoints noted directly behind the seabreeze today. This is forecast to result in heat indices around 100-105F today across much of ENC. While the seabreeze will likely kick off convection once again today, much like yesterday think there is some time for heat indices to reach heat advisory criteria prior to thunderstorm initiation. Have issued a heat advisory mainly along and south of Greene and Pamlico County today starting at 11AM as I have the highest confidence of reaching criteria here. This foot print also follows the major heat risk footprint pretty well. Will note an expansion could be needed this morning like yesterday if we quickly heat up out ahead of thunderstorm activity. Even if we dont reach explicit criteria it will be hot and muggy today so make sure you are taking proper precautions if headed outside for an extended time period today.
KEY MESSAGE 2, Isolated showers noted across the OBX and the offshore waters this morning and expect precip to continue to wane in coverage through daybreak as yesterdays mid level shortwave pushes further offshore. However, still expecting an active precip pattern into Wed. An additional shortwave is forecast to track across the region this evening while the seabreeze pushes inland. At the same time, surface troughing remains in place to the west. The seabreeze and surface trough remain the focus for thunderstorm activity today. Then tomorrow a backdoor cold front/seabreeze combo will be the focus for thunderstorm activity. Guidance continues to suggest PoPs remain around the 50-80% range each day with highest PoPs noted in the afternoon/evening. Much like yesterday, precip will certainly be very hit or miss across ENC.
No real changes to forecast thinking for today and tomorrow. A rather moist airmass is expected to remain in place across ENC over the next few days with PWATs generally ranging from 2-2.5 inches through Wed. Combined with ample heating across ENC, instability will rapidly build each day with MLCAPE values generally expected to be between 1500-2500+ J/kg each afternoon. While instability will certainly be plentiful, deep layer shear will not be, as wind shear struggles to get above 25 kts. This will likely limit any significant storm organization, but cannot rule out some wet microbursts or stronger winds (40-60 mph) within the strongest storms along the seabreeze and surface trough today. Because of this, SPC has outlined a good portion of ENC in a Marginal Risk (1/5) for severe tstorms today. Another round of afternoon showers/storms is possible Wed as the aforementioned front moves through, once again bringing a severe threat to ENC given the similar airmass. Spc has portions of ENC under a marginal risk (level 1/5) for severe weather as well on Wed with damaging winds (40-60 mph) being the main hazard within the strongest storms. In addition to the severe threat today and tomorrow, there will also be a heavy rain threat with any thunderstorm that develops given the high PWAT's (2" +) and slow storm motions which could lead to some localized flooding mainly in poor drainage and urban areas. As a result WPC also has kept much of the area under a marginal risk for excessive rainfall over the next two days as well.
Beyond mid week, 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 100-105 in the forecast.
KEY MESSAGE 3, Not much change in forecast thinking from Thurs onwards as low level thicknesses remain around normal values which places inland temps in the mid to upper 90s across ENC. 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 heat advisories may come into play later this week.
KEY MESSAGE 4, With the aforementioned high heat and humidity expected Thurs into this weekend, a very unstable atmosphere develops with the potential for ML CAPES to near 3500 J/KG each day, and SFC based instability between 4000-5000 J/KG. As is typical this time of year, deep layer shear will not be too strong, but any storms that can develop with some upper level support could produce strong downdraft/microburst winds and very heavy rain characterized by PW's exceeding 2". Will also be monitoring Sunday as the next potential front makes an appearance across ENC which could help to focus thunderstorm activity and bring more shear to the area.
12z Tuesday through Saturday Some patchy low stratus and ground fog remains across portions of our NW'rn zones this morning but this should quickly lift within the next hour or so. All TAF sites are currently VFR as of this update and should remain that way over the next few hours. Outside of the TAF sites, some brief periods of sub-VFR conditions are possible near MRH as a line of heavy showers moves through. Once this rain activity pushes off the coast expect VFR conditions across all of ENC until the next round of thunderstorms this afternoon. Much like yesterday, expect increasing shower and thunderstorm chances late this morning and afternoon. Have maintained the PROB30/TEMPO groups to mention this threat with general timing at all TAF sites after 18Z today. Any TSRA that develop today will be capable of 30-45kt winds and significant reductions to VIS. Showers and thunderstorms once again wane tonight with another round of low stratus and patchy fog possible.
Outlook (Wed through Sat): A backdoor cold front will track across the region on Wed bringing yet another chance for showers and thunderstorms and potential for sub-VFR conditions. Beyond Wed, more typical iso to widely sct activity expected as ridging rebuilds into ENC so a much lower threat for sub-VFR conditions.
As expected 15-25 kt SW'rly winds with gusts up to 25-30 kts are occuring across the coastal waters south of Oregon Inlet and the Pamlico Sound this morning where ongoing SCA's are noted. Weaker winds at 5-15 kts are noted elsewhere while seas remain around 2-5 ft offshore. These conditions will persist into daybreak before easing this morning thus ending the ongoing SCA's. Expect 10-20 kt SW winds today with 2-5 ft seas keeping things just below SCA levels for the most part. There will be the potential for another round of SCA conditions across the coastal waters and Pamlico Sound tonight, though this looks less likely than this mornings SCA's so have not added additional SCA's across these waters just yet. Regardless do expect winds to ease close to daybreak Wed once again. Scattered showers and thunderstorms will also be possible across our waters today and tonight as a shortwave moves through bringing a threat for locally enhanced winds and seas.
Outlook (Wed through Sat): Weakening front moves into the waters on Wed, though as is typical in July, the front appears to wash out, with any N'rly flow behind it short lived with return flow developing Wed evening. Sw'rly winds look to strengthen some on Thurs/Fri as a thermal trough strengthens across the area bringing our next potential threat for SCA's to the waters.
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.
