textproduct: Newport/Morehead City

WHAT HAS CHANGED

Scattered strong to severe thunderstorms will be possible Saturday afternoon and evening, with the main threat of damaging wind gusts.

KEY MESSAGES

1) Expecting hot and humid conditions this weekend with highs in the 90s, and heat indices around 100-105 Sat and Sun.

2) Multiple shortwaves and a backdoor cold front bring increasing chances for showers and thunderstorms this weekend, with severe potential Saturday PM.

3) Dangerous heat likely mid to late next week heading into the holiday weekend.

DISCUSSION

KEY MESSAGE 1...A WAA regime will persist into this weekend as high pressure becomes centered offshore. This will bring continued SSW winds and increasing low level thicknesses to ENC. Latest guidance continues to show low level thicknesses generally around 1410-1425m which support highs into the low to mid 90s each day. With temps in the low to mid 90s and dewpoints in the upper 60s to low 70s heat indices will likely peak around 100-105 Saturday and Sunday. Will note with an increase in precip chances especially Sat/Sun, mentioned in key message 2 below, there is larger than normal uncertainty in explicit heat index values. So while heat advisories are certainly possible Sat/Sun, it is not a given as these values will be highly dependent on thunderstorm timing and coverage. Based on the current forecast and ensemble probs, will hold off on heat headlines for now. Sunday chances are highest south of where the back door cold front ends up by the afternoon hours. With lows only getting into the 70s each night this weekend there wont be much relief from the heat. If you have any extended plans outdoors this weekend make sure to stay properly hydrated and take proper precautions when outside.

KEY MESSAGE 2...Multiple shortwaves will transit across the Mid-Atlantic this weekend bringing the potential for a few rounds of scattered showers and thunderstorms. Scattered showers and iso storms beginning to blossom along and west of Hwy 17 and north of Hwy 70 this afternoon...aided by the seabreeze and approaching shortwave. Weak shear still looks to be a limiting factor with stronger storm/svr potential this afternoon, but cannot rule out a stronger storms with gusty winds 40-50 mph developing. Convection likely to wane with loss of heating this evening.

Sat, a slightly stronger shortwave looks to impact the Carolinas with a surface trough setting up across the coastal plain. This is forecast to result in slightly more widespread shower and thunderstorm activity Sat afternoon and evening (40-60%). On top of that, with continued SW'rly flow, low level moisture will maximize on Sat/Sun and with ample surface heating MLCAPE values increase to 1000-2000 J/kg Sat afternoon with some guidance suggesting MLCAPE values as high as 1500-3000 J/kg. With deep layer shear also increasing slightly on Sat closer to 25-35 kts there is the potential for a few stronger thunderstorms to develop bringing a threat for downbursts and gusty winds (40-60 mph) within the strongest storms. SPC continues to outlook much of the area in a Slight risk (2/5) for Saturday. While strong storms are possible in the afternoon, there is also potential for weakening MCS activity to move into the area from the W/NW after sunset, keeping svr threat going into later evening.

The strongest shortwave looks to impact the area on Sunday associated with an incoming backdoor cold front which would likely bring the best precipitation coverage. Backdoor front looks to track from north to south Sun afternoon and evening providing the focus for scattered showers and thunderstorms. Once again can't rule out a stronger storm or two especially across the southern OBX and Crystal Coast where the best instability and shear axis will be but for now only expecting sub-severe thunderstorms. Will note given the nature of shower and thunderstorm activity it will not be a washout any of these days with showers and storms likely being hit or miss across the area.

KEY MESSAGE 3...No significant changes to the extended forecast as an omega block sets up across the Eastern CONUS with anomalous ridging persisting across the the midwest and eastern US next week. This will bring the potential for an extended period of dangerous heat to ENC starting around Wed next week and continuing into the July 4th weekend. GEFS probs of high temps > 100F have increased slightly to 30-50% for inland locales during this time period. Meanwhile, EPS probs have trended down to near 0% through July 3rd for ENC, with better chances along and west of I-95. NWS probabilistic Heat Risk values of reaching major heat risk levels or higher are currently sitting at about 40-60% on Wed, 70-90% on Thurs, and 80-90% on Fri/Sat which is fairly notable given the higher end values this far out. Those sensitive to heat and anyone planning on spending ample amounts of time outside later next week should continue to monitor the forecast trends as this potential heat wave would have impacts on the holiday weekend. CPC has highlighted the Carolinas in a high risk of extreme heat July 2-4.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

VFR conditions across the terminals this afternoon, with scattered showers and iso storms developing. Periods of sub-VFR possible with afternoon convection, best chances west of Hwy 17. There is potential for low stratus to move in early Sat morning, with best chances between 10-15z along the coastal plain. Scattered to numerous showers and storms likely to develop Sat afternoon and evening, some storms may become strong to severe with the main threat of damaging wind gusts.

Outlook (Sat night through Wed): Could see some isolated showers and thunderstorms along the seabreeze again Sat afternoon bringing a brief period of sub-VFR conditions to any area impacted by this activity. A front then tracks across the area on Sun bringing a bigger threat at sub-VFR conditions. However, by Mon VFR conditions return and persist into Tue.

MARINE

Latest obs show SW winds 5-15 kt with seas around 2 ft this afternoon. SSW winds will to 10-20 kt this evening with seas building to 2-4 ft. Moderate to breezy SSW winds will continue Sat, with potential for a period of 25 kt gusts developing in the afternoon and evening for the coastal waters, Pamlico/Croatan/Roanoke sounds. Will hold off on SCA for now but may need to be issued with later shifts.

Outlook (Sat night through Wed): Pinched pressure gradient and thermal gradient Saturday PM brings a risk of SCA conditions to coastal waters/Pamlico/Croatan/Roanoke sounds with SW gusts around 25 knots. Gulf stream showers and thunderstorms possible through Sun with the shortwave and back door cold front. Winds will eventually shift from the SW to the NE on Sun and Mon from N to S behind the aforementioned front.

MHX WATCHES/WARNINGS/ADVISORIES

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