Key MESSAGE 1, Notably warm low-level thicknesses beneath an anomalous mid-upper level ridging will continue to support above to well above normal temperatures across the Carolinas through tomorrow. Guidance shows similar low-level thicknesses this afternoon and tomorrow's yielding highs generally in the lower 90s across the coastal plain, but some warmer spots may reach mid 90s. This will fall a few degrees short of records, but is still around 10 degrees above normal for mid to late May.
Additionally, despite increasing low-level moisture, ridging aloft will provide sufficient subsidence to suppress convective activity outside of perhaps a rogue shower or thunderstorm where convergence is maximized along the seabreeze (the usual suspect spots over Dare County and Down East Carteret come to mind here). Still, probs of this occuring are low enough to keep out of the forecast this afternoon.
KEY MESSAGE 2, The mid-upper level ridge is forecast to break down some starting Thursday and into the weekend, allowing a front to drop south late Thursday into Friday and then stall as it encounters the persistent ridging that has been over the region for much of the past week. Confidence continues to increase on the front reaching our CWA, with the most likely outcome being the front briefly stalling between the NC/SC border and Cape Hatteras. The front will likely linger over the area for a couple days before the boundary eventually lifts back northward over the weekend with ridging building back in its wake. The trend of a slower frontal passage has held this morning, with the front not reaching our area from the north until mid-afternoon. Therefore, forecast highs will once again reach the 80s and 90s with persistent southerly flow.
Increasing moisture and instability along the frontal zone should support an increased risk of showers and thunderstorms Thursday into the weekend. Probabilistic guidance depicts a 30-40% chance of over a quarter inch of rainfall, especially along and north of Highway 64 along the frontal boundary on Thursday. Ahead of the front, the pre- storm environment should be sufficiently unstable for a few storms as CAPE rises to 1000-1500 J/kg. With forecast steep low-level lapse rates and modest dry air aloft, combined with PWATs in the 1.5-1.75" range, the environment would be marginally conducive for the risk of a strong downburst in a more organized storm. Said organization, however, would require some amount of deep level shear and this appears lacking with 0-6 km values under 20 kt. The odds of a stronger storm appear to be around 10% or less as of this afternoon, in line with CSU and NCAR ML guidance, but trends will continue to be monitored. The severe risk will likely be muted on Friday with the frontal boundary to our south, then return to a low-probability regime for Saturday. Beyond here, the front becomes weak enough that diurnal sea and sound breezes become dominant, focusing the highest shower and thunderstorm chances inland. Each of these days carries a low, highly conditional severe risk as well per ML guidance.
Notably high PWATs along the frontal zone should support higher rainfall rates in convection. However, notable hydro impacts are not expected due to the recent dry stretch and ongoing drought conditions. While probs are low, if we do see training storms over urban areas like Greenville, Jacksonville, and New Bern, minor flooding impacts could be seen despite the ongoing drought.
18z Tuesday through Sunday VFR conditions across the terminals this afternoon. Given the similar set up and little change to the airmass, fog and low stratus chances return with another night of light winds and low level moisture. Best chances at OAJ/EWN/ISO. Locally dense fog will be possible. Conditions improve quickly after 12z.
Outlook: A frontal boundary sagging south into ENC is expected to bring an increasing risk of SHRA, TSRA, and sub-VFR conditions Thu into the weekend.
A summer-like pattern continues through tomorrow, with a daily building of winds to 10-20kt each afternoon and evening as the thermal gradient tightens. This will especially be the case for the inland rivers and sounds and the nearby coastal waters within 20nm of the coast, where funneling could result in some brief periods of 25kt gusts in the afternoon. Seas will continue to hover around 2-3ft, potentially up to 4 ft during the afternoon and evening.
Outlook: A frontal boundary is forecast to sag south into the area Thursday, then meander around the area through the upcoming weekend. This leads to lower confidence regarding winds and seas, but especially wind direction. In general, the risk of 25kt+ winds appears low during this time ahead of the front, with slightly higher chances of seeing 25+kt gusts behind the front across the Ablemarle Sound and adjacent waters on Thursday afternoon and evening. There will be an increased risk of thunderstorms in the region Thursday through Sunday as well.
Nc, none. Marine, none.
