Key MESSAGE 1, Latest surface analysis this afternoon shows frontal boundary has cleared ENC and now sits offshore, leaving our area in partly cloudy skies. The front will help nudge temperatures down slightly compared to yesterday, felt most across the Albemarle Peninsula and northern Outer Banks with relatively cool onshore NW flow. Farther south and west, however, will see little relief as temps once again climb back into the mid 90s and Tds remain unrelenting in the upper 70s. Heat Advisory remains in effect for counties south of US264 into this evening.
Boundary remains to our south for much of Sunday, but temperatures have trended slightly lower tomorrow with likely lingering convective debris and potentially earlier start of convection. No Heat Advisories issued for tomorrow, although spots from Lenoir County southward may get close to 105 for an hour or two. Higher confidence in dangerous heat remains on Monday as the front lifts north and re- entrenches ENC in a very hot airmass with 1000-850 mb thicknesses once again climbing above 1430m and widespread Tds in the mid to upper 70s. This could nudge max heat index values above 110 in many areas. We continue to encourage anyone planning on spending time outdoors to stay hydrated and to limit exposure to the heat, if able.
Another frontal boundary quickly pushes across NC on Monday evening before stalling along the coast. Like this weekend, SW counties will likely remain hot and humid while Albemarle and vicinity see some modest relief. A more widespread cooldown, however, is on the horizon late next week as a stronger cold front dives out of Canada and across the eastern CONUS.
KEY MESSAGE 2, Environment today once again appears at least marginally conducive for shower and thunderstorm development as ENC sits in northwesterly flow aloft and multiple mid-level disturbances rotate around a mid-level ridge stubbornly sitting over the Gulf States. Coverage today will be a touch better than yesterday, aided by sea and sound breezes as well as enhanced low-level convergence along the aforementioned frontal boundary. This most favors storm development, at least initially, along the southern coastline. Later in the day, upstream convection expected to develop in the NC Piedmont and southwest VA will migrate southeastward and potentially graze the coastal plain in the evening hours, although CAM consensus most favors areas west of I-95.
Pre-storm environment, like yesterday, is only marginally conducive for stronger storms with effective shear near 20 kt but ample instability forecast to reach 2500-3000 J/kg. An isolated wet microburst is possible, but a greater risk for stronger winds would be tied to more organized convective complexes likely to our west. Flooding threat today is more readily apparent - although storms will be somewhat progressive, impressively high PWATs and sufficient saturation up to 500 mb point to highly efficient rainmakers easily capable of rainfall rates exceeding 2"/hr. Isolated flash flooding is possible, particularly for urban locations or those with known susceptibilities.
Frontal boundary begins to lift northward on Sunday, shifting more robust convection threat closer to VA but still leaving a favorable environment for sea breeze activity, as well as some upstream threats once again making their way towards the area in the evening. Evolution will be heavily driven by mesoscale factors owing to continued higher than average forecast uncertainty owing to large spread in CAMs.
Another frontal boundary looks to approach on Monday. There will still be plenty of details to hammer out but both AI and trusted deterministic NWP guidance point to at least another marginal risk of strong to severe storms associated with this boundary. It will stall along our coast next week, keeping our area in an unsettled pattern through most of the work week.
18z Saturday through Thursday VFR conditions in place this afternoon as cold front sits south of terminals. Main threat for aviators will be convection, focused initially south of EWN along the stalled frontal boundary and coupled with the diurnal seabreeze. Later in the evening, bands of convection dropping southeast from the NC Piedmont may graze inner coastal plain terminals through 00z. Stronger convection could bring winds of 40+ kt as well as torrential rainfall briefly limiting visibility.
Lingering showers diminish overnight, but with post-frontal low odds have increased for low stratus and potentially fog, highest chances west of a line from OCW-EWN. Did lower forecast cigs from previous cycle with GLAMP showing increasingly bullish probabilities north of 50%. Conditions should gradually improve to VFR Sun morning, but may hold at MVFR for a few hours after sunrise.
Outlook (Sunday through Wednesday): More isolated TSRA activity is possible, mainly Sun evening. Otherwise, mainly VFR conditions expected into Monday. Then as we get into Mon evening and Tue more widespread threat for sub- VFR conditions is possible on ahead of the next front before VFR conditions return Tue into Wed.
Cold front has largely cleared area waters this afternoon with sound and sea breezes becoming dominant. Winds are primarily out of the northeast at 10-15 kt except along the Crystal Coast where sea breeze has turned winds out of the south. Seas are around 2 feet with a 6 sec wind wave, although some underlying 12-13 second swell lingers. Scattered showers and thunderstorms likely across Onslow Bay waters this afternoon, with lower probabilities farther north.
Outlook (Sunday through Wednesday): Marine forecast, in terms of winds and seas, is largely benign with the next focus for SCA on Monday as another cold front approaches area waters. This, coupled with a healthy thermal gradient, will likely boost southwesterly winds back to 15-20 kt with some spotty gusts to 25 kt. At this time, coverage of SCA conditions appears too limited to need a headline but forecast trends will be monitored. Beyond this, next potential for SCA is late next week. Each day will bring a low to moderate risk (20-40%) of showers and thunderstorms to area waters.
Nc, heat advisory until 8 pm EDT this evening for ncz044-079-080- 090>092-094-193>196-198-199. Marine, none.
