textproduct: Newport/Morehead City

WHAT HAS CHANGED

Updated aviation discussion.

KEY MESSAGES

1) Locally dense fog possible for the Wed morning commute for portions of ENC Wed morning.

2) Above normal to near- record high temperatures and rain- free conditions to continue Wednesday.

3) A frontal system approaches the area Thursday, bringing the next appreciable chance of showers and thunderstorms through the weekend

DISCUSSION

KEY MESSAGE 1...Days of moisture advection has resulted in dewpoints in the upper 60s to near 70F across eastern NC. High pressure centered offshore is keeping winds light to calm across SW portions of the CWA, with decoupling allowing for the near surface layer to reach saturation. Areas of fog and low stratus will again be possible, esp across the SE forecast area. SPS or Dense Fog Advisory may eventually be needed. Conditions should rapidly improve by 9AM as strong daytime heating scours out any fog/low stratus.

KEY MESSAGE 2...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 Wednesday. Guidance shows similar low-level thicknesses each afternoon yielding highs generally in the lower 90s across the coastal plain but some warmer spots may reach mid 90s, remaining just shy of records. It will be closest across the coastal plain, however.

Additionally, despite increasing low-level moisture, ridging aloft should provide sufficient subsidence to suppress convective activity outside of perhaps a rogue shower or thunderstorm where convergence is maximized along the seabreeze. Still, probs of this occuring are low enough to keep out of the forecast with this update.

KEY MESSAGE 3...The mid-upper level ridge is forecast to break down some late-week and into the weekend. This should allow a front to drop south Thursday into Friday as it encounters the persistent ridging that has been over the region for much of the past week. Confidence is increasing on the front reaching our CWA, with the most likely outcome being the front briefly stalling between the NC/SC border and Cape Hatteras. Once the high to the north shifts offshore this weekend and ridging strengthens again to our south, the warm front will get clearance to shift back north. The front has trended a bit slower to reach the CWA with this update. As a result, we are forecast to have enough residence time of warm southerly flow Thursday morning and afternoon ahead of the front to see high temps in the upper 80s to near 90 inland.

Increasing moisture and instability along the frontal zone should support an increased risk of showers and thunderstorms Thursday into the weekend. Probabilistic guidance shows a solid chance of 0.25"- 0.75" each day. However, it should be noted that those amounts will be highly dependent on the evolution of the frontal zone. Initially when the front drops into the area, there may be just enough flow aloft to support some thunderstorm organization. Model soundings show steep low level lapse rates and weak turning of low level winds ahead of the frontal passage Thursday and Saturday. A layer of dry air aloft could inhibit deep convection, but if updrafts are able to break through this, DCAPEs of 600-1000 J/kg could support a risk of strong to marginally severe winds. On the flip side, upper level dynamics and deep shear look unimpressive and could inhibit organized tstorms. This setup will be something to monitor the day of, with the later frontal passage timing allowing for greater instability Thursday. Friday, lower surface temps keep low level lapse rates more muted, and as a result a severe risk isn't present. Machine learning and analog guidance support the potential for strong to severe tstorms Thursday and Saturday as well.

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.

AVIATION /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.

MARINE

A summer-like pattern continues through Wednesday, 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. Seas will continue 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. There will be an increased risk of thunderstorms in the region Thursday through Sunday as well.

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...None.