Key MESSAGE 1, Current analysis this morning depicts a complex mid-level pattern with three distinct shortwaves digging across portions of the Great Lakes, Midwest and MS Valley while primary jet axis sits just to their east over the spine of the Appalachians. At the surface, main feature of interest for us is a stalled to slow moving front sitting across far western NC which is just now beginning to push eastward. Pre-frontal trough ahead of it is driving a broken band of showers and a few embedded thunderstorms extending roughly along the I-85 corridor.
The forecast for today has changed little, with widespread showers and a few thunderstorms developing late this afternoon as the aforementioned front finally makes its way through our area. Most CAMs continue to depict some isolated showers migrating NEward off the water along the pre-frontal trough. This is certainly possible although it is worth noting this is a common artifact in guidance that has a very mixed history of being realized. If such activity does develop, it could modestly hamper destabilization through the day. In either scenario, a minimum of around 500 J/kg MLCAPE (worst case scenario 1000 J/kg as suggested by the HRRR) to be in place this afternoon across the region fueled by above average moisture and temperatures in the mid to upper 70s. This is unusually high for early November, supported by EFI highlighting CAPE values in the 75-80th percentile.
In addition to instability, respectable low-level shear will be present ahead of the front with 0-1 km values potentially reaching 20-25 kt. This will support a pre-storm environment that could support organized convection and possibly low-topped supercells in the afternoon and evening hours. The primary hazard would be damaging winds, but model hodographs do show low-level veering suggesting a brief tornado is not implausible.
The main threat window runs from early afternoon to around sunset inland, lingering slightly longer over the Outer Banks but with a diminishing severe risk as instability collapses. The main front sweeps offshore late tonight with any remaining showers exiting the OBX around or shortly after midnight. There will likely be a delay between the main front coming through and the dry air surge, so would not be surprised to see a period of low stratus Fri night into Sat morning.
KEY MESSAGE 2, A more seasonably dry airmass will be ushered in for the weekend behind the front. Expect a return to mostly sunny skies and highs in the upper 60s to low 70s Sat, then cooler yet for Sun with 60-65. Lows will be in the 40s, with some 30s for some of the normally colder spots. We will have to monitor the temp forecast for any frost concerns Sunday morning.
12z Friday through Tuesday Forecast confidence is moderate over the next 24 hours.
A strengthening cold front will move east across central and eastern NC today, eventually moving offshore by tonight. Scattered SHRA and TSRA will accompany the front, some of which could produce wind gusts in excess of 40kt. There will also be a risk of significant reductions to VIS (LIFR/IFR). While not likely, a low-end tornado risk is present as well, mainly for inland TAF sites. Ahead of the front and TSRA, gradient/mixing winds will be capable of gusts up to 20-25kt out of the south.
The most uncertain part of the forecast is CIGs. Cig heights have varied between 2500ft and 8000ft this morning, and this will probably continue until the front gets closer. At that point, CIGs should fall into the 2500ft to 4000ft range. In the wake of the cold front, guidance insists on a period of low CIGs due to residual low- level moisture. During this time, CIGs may fall as low as IFR/LIFR for several hours.
Outlook: An extended period of VFR conditions is expected after today's TSRA as a much drier airmass builds in across the region.
Light to moderate southerly winds will continue through the period (strongest across the outer southern and central waters). Seas will persist at 3-5 ft nearshore and near 4-6 ft offshore through today. A cold front moves through this evening into the overnight hours for our waters, and ahead of this boundary strong thunderstorms capable of gusty winds and a brief waterspout are possible. Behind the front, winds switch to the north/northwest, gusting to near 20 knots. Gusts exceeding 25 kt will likely be concentrated beyond 20nm offshore, so no headlines were offered this morning.
Outlook (Saturday through Tuesday): High builds in this weekend into next week, keeping winds below 20 kts and skies rain-free. Despite the decrease in winds, elevated seas may linger through the weekend for 20-60nm zones at around 4-6 feet, and an isolated 6 foot wave is possible just within 20nm primarily for waters in Raleigh Bay.
Nc, none. Marine, none.
