textproduct: Newport/Morehead City

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1) Risk of dangerous heat later this week.

2) Pattern expected to become more conducive for showers and thunderstorms mid-week into early next week.

DISCUSSION

KEY MESSAGE 1...Very warm low-level thicknesses are forecast to overspread the Carolinas from mid-week on as we get into a WSW low- level flow pattern. Once again, 00z guidance have trended warmer, and this continues to support an increased confidence in above normal temperatures. The caveats each day will be the coverage of convection (see KEY MESSAGE 2 for additional details), and the potential for high clouds/convective debris. Both of those factors can have significant impacts on the temperature forecast each day. Regardless, persistent southerly flow will allow dewpoints to steadily rise through the 60s and 70s each day. This will lead to higher humidity and increasing "feels like" temperatures even on the days with convection/clouds. Right now, it appears Friday may have the lowest coverage of thunderstorms, and the hottest temperatures of the week. Probabilistic guidance currently shows a 50-70% chance of exceeding 95 degrees for inland areas away from the coast. This combined with dewpoints in the low 70s suggests a widespread area of "feels like" temperatures of 100-105 degrees. This setup could lead to the first heat headlines of the summer season. The NWS' experimental Heat Risk guidance shows much of ENC in the major category, with a few areas nearing the extreme category.

KEY MESSAGE 2...From a 50,000ft perspective, the synoptic pattern is expected to shift towards something more favorable for convection across ENC from mid-week into early next week. However, this shouldn't be read as a high coverage of thunderstorms each day. It simply means the potential is there to not be nearly as dry as we have been lately.

Initially, yesterday's cold front will flip around and lift back northeast as a warm front tonight. A few showers may accompany this front as it moves through. In the wake of this front, an upper level shortwave is forecast to move through the Mid- Atlantic and Carolinas late Wednesday into Thursday. This wave is forecast to interact with a moistening and gradually destabilizing airmass, supporting clusters of convection from Virginia south into North Carolina. Locally, temps aloft will be very warm, with 850 temps of 15-20C. This will have a tendency to support some residual capping, and may tend to lead to a weakening trend with any convection that approaches our area from the west/northwest. Given the increased forcing with the wave, though, it stands to reason that at least some weak, elevated convection could survive into the area, and the forecast reflects this potential. Very warm temps aloft may continue to cap a greater coverage of convection into Friday. Over the weekend, temps aloft "cool" slightly, and this may support at least a risk of seabreeze convection. Early next week, guidance is now hinting at the potential for a front to move through with an increased risk of convection. Additionally, deep layer shear of around 30-35kt along the front may support a modest increase in the potential for organized convection, some of which could be on the strong side. Outside of Monday, shear looks fairly weak each day, with a marginal, pulse severe environment each day.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

A dry, post-frontal airmass is now fully entrenched across ENC. On the fringe of this airmass is a ribbon of low CIGs that stretches from SE North Carolina north through SW Virginia. Over the past few hours, this area of low CIGs has crept north along the Crystal Coast, and may briefly impact KOAJ and KEWN. An easterly low-level flow should prevent those lower CIGs from reaching KISO and KPGV. For now, I've added a TEMPO IFR group at KOAJ. Confidence is slightly lower at KEWN, therefore I have opted to hold off on adding a TEMPO group and have, instead, highlighted this potential with a SCT IFR level group.

Light and variable winds this morning will slightly increase and become southeasterly by mid to late afternoon into the early evening hours as the seabreeze moves inland. SCT cumulus development appears likely along the seabreeze, but the risk of SHRA and TSRA looks low (<5% chance).

Outlook (Wednesday through Sunday): A warm front will lift northeast across ENC Tuesday night and may be accompanied by a few SHRA. A period of low VFR CIGs may develop along this front as well. From Wednesday into Thursday, an upper level wave may combine with a moistening and destabilizing airmass to support a TSRA and sub-VFR risk. Occasionally gusty south to southwest winds are expected mid-week as well. In general, the weather pattern looks to continue to be supportive of a daily TSRA risk into the weekend.

MARINE

Despite high pressure building in, the gradient remains tight enough to support NE winds of 10-20kt as of 3am. The gradient is expected to quickly relax by sunrise this morning, with winds becoming easterly and laying down to 5-15kt. Seas will eventually follow suite, laying down from 3-6ft this morning to 2-4ft by this afternoon. The one exception is the outer waters where 4-6ft seas are forecast to last through tonight.

Winds will become southeasterly by this evening, then southerly tonight, as high pressure shifts offshore.

Outlook (Wednesday through Sunday): A typical summertime regime returns from Wednesday onwards, with a daily building of southwesterly flow each afternoon and evening as the thermal gradient tightens. Occasional periods of 25- 30kt winds will be possible during this time, especially Wednesday- Friday. Seas of 3-5ft will be common. The risk of thunderstorms will gradually increase from mid to late-week as well, but widespread thunderstorm activity is not anticipated on any day for now.

MHX WATCHES/WARNINGS/ADVISORIES

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