Key MESSAGE 1, Today, daytime heating of the airmass in the vicinity of the seabreeze and any residual boundaries from early morning convection should support a renewed risk of thunderstorms. Once again, some of these could be strong to marginally severe. Residually dry air aloft should support DCAPE values of 1000+ j/kg. This in tandem with steep low-level lapse rates and moderate instability should lead to the primary risk being damaging winds of 40-60 mph. Forecast aids like the ECMWF's EFI show a decent environmental signal for a few severe thunderstorms which is also supported by short-range ensemble guidance. The convective potential this afternoon should primarily be diurnally-driven, with the risk decreasing after sunset.
KEY MESSAGE 2, An anomalously strong upper level trough is forecast to develop over the Mid-Atlantic Region on Tuesday, with a potent shortwave diving southeast through Virginia and the Carolinas Tuesday into Tuesday night. A strong LLJ ahead of this feature should lead to increasing moisture advection, with PWATs once again climbing back above 2". Meanwhile, heating of a moist boundary layer should support moderate instability, with MLCAPE rising into the 1000-1500j/kg range. Aloft, a notable upper jet max is forecast to overspread the instability axis, supporting deep layer shear of 30-45kt. While instability will be moderate, the shear/instability combo is notable for this time of year, as is the amount of lift expected.
Synoptically, the combination of all of the factors above checks several boxes for severe weather potential. This also has overwhelming support from ensemble, analog, and machine learning guidance. The main potential limiting factor is timing. Some guidance suggests convection may not reach ENC until after sunset. Despite the potential for a gradually stabilizing boundary layer, the strong large-scale forcing should help support deep convection well past the typical diurnal max in convective intensity this time of year. Given the amount of forcing present, it appears likely that an MCS will move through ENC during the evening and early overnight hours posing a risk of damaging winds. Low-level SRH around 100m2/s2 may support a few rotating updrafts capable of hail and perhaps a brief tornado. However, those latter 2 hazards should be lower compared to the wind risk. Lastly, while a MCS would be more progressive, the high PWAT airmass should support heavy rainfall rates which may support a short-fused flooding risk, especially for the area hardest hit the past few days (ie. Hyde County east through the Outer Banks).
Ahead of the convection, hot and humid conditions are expected, with heat indices rising to 100-105 degrees. This appears to be a bit marginal for heat headlines, but is something we'll continue to assess in later forecasts.
10z Monday through Friday Mix of VFR and MVFR conditions across the terminals early this morning. Still some signal for MVFR stratus and patchy fog early this morning, mainly across the coastal plain. Vfr should return by 15z. This afternoon, increasing moisture and instability should lead to vcts for most TAF sites after around 18Z, though covg not high enough attm to warrant a TEMPO group yet. Iso strong to severe storms with gusty winds possible. Convection would wane with loss of heating this evening, with potential for patchy fog overnight.
Outlook (Tuesday through Friday): A notably strong storm system for this time of year is forecast to impact the area later Tue. This system will be accompanied by gusty winds and an increased risk of TSRA Tue evening, some potentially severe. Sub-VFR conditions are expected to accompany the TSRA risk. The strongest storms will be capable of 40-60kt winds and small hail. Much drier behind the fropa for Wed into the end of the week as high pres rebuilds.
Latest obs show light S-SE winds less than 10 kt across the waters, with seas 2-3 ft. Light SE winds 5-10 kt will continue today, becoming southerly tonight. Scattered showers and storms expected this afternoon, which could bring gusty winds.
Outlook: A strong frontal system is forecast to impact the waters Tuesday into Wednesday with building winds and seas and an increased risk of thunderstorms. Winds of 15-30kt are expected late Tuesday into early Wednesday morning. Seas are forecast to peak in the 4-8ft range. Of note, a cluster of thunderstorms moving through Tuesday evening and Tuesday night will be capable of 40-50kt winds and hail.
Nc, none. Marine, none.
