Key message 1,
On Monday, a cold front will move south along the coast of NC during peak heating. West to northwest low-level flow should tend to limit the strength of convergence along the front. However, as the front encounters the developing seabreeze, there should be a local enhancement to low-level forcing, especially along and south of HWY 70. This is the area where the best chance for sustained, deep convection exists. The risk is conditional on sufficient low-level forcing, but should this occur, a short-lived risk of strong to marginally severe thunderstorms may develop thanks to elevated deep layer shear (~30kt) and moderate instability (MLCAPE up to 1500j/kg). Machine learning guidance isn't all that excited about this potential, and this likely speaks to the conditionality of the threat. This risk will quickly end from north to south as the front shifts off the Crystal Coast by sunset.
KEY MESSAGE 2, Guidance continue to trend stronger with an upper level ridge that will be expanding across the Southern U.S. This week. In fact, ensemble guidance is now forecasting 500mb heights around 600dm with this ridge, the strength of which is very unusual for this time of year. Normally, this would spell anomalous heat for ENC. However, a pocket of "cooler" thicknesses is forecast to be over the Carolinas associated with the post-frontal northeasterly flow regime, especially Tuesday and Wednesday. While it will be dry, those cooler thicknesses may shield ENC from the anomalous heat that other parts of the South will experience. That pocket of lower thicknesses may begin to erode by the end of the week, with temperatures warming by then. However, guidance differ on when/if this will occur.
00z Monday through Friday A slightly drier westerly flow tonight may limit the risk of low CIGs and VIS. However, light winds, recent rainfall (for some), and residual low-level moisture may still allow periods of reduced VIS in MIFG, but not enough confidence or covg to include in the TAF fcst attm.
Another risk of SCT TSRA is expected on Monday afternoon along a cold front that will be moving south through ENC. There is the potential for some of the thunderstorms to become strong, capable of gusty winds of 40kt+. This risk is contingent on sufficient instability and lift developing along the front. Will not mention thunder in fcst attm as coverg may be quite isolated in nature, and best chances east of the TAF sites. A nerly wind shift, and a bump up in winds, is expected behind the front. Wind gusts as high as 20-25kt will be possible for a few hours behind the front late Mon.
Outlook (Mon night through Fri): High pressure builds in through the middle of the week with mostly VFR conditions expected. The high should also keep a lid on precip through at least mid week.
Southerly winds of 10-15kt will continue into this evening ahead of a surface trough that is approaching from the west. That trough will move through area waters this evening and tonight with the winds becoming westerly, and laying down to 5-10kt. Northerly winds then quickly build from north to south on Monday as a cold front moves through. Deterministic and ensemble guidance continue to show a strong signal for 25kt winds within the post-frontal northerly surge of wind, and marine headlines have been issued to account for this.
Outlook: An extended period of northeasterly flow is expected through at least Wednesday or Thursday. Winds are forecast to lay down below 25kt, but elevated seas may linger for much of the week, especially with the contra flow against the Gulf Stream waters. For the near-shore coastal waters, the Small Craft Advisories may need to be extended into mid-week depending on how long the elevated seas last.
Nc, none. Marine, small craft advisory from 2 pm Monday to 2 am EDT Tuesday for amz131-150-230-231. Small craft advisory from 5 pm Monday to 2 am EDT Tuesday for amz135. Small craft advisory from 5 pm Monday to 8 pm EDT Wednesday for amz152-154. Small craft advisory from 8 pm Monday to 2 pm EDT Tuesday for amz156-158.
