textproduct: Newport/Morehead City

WHAT HAS CHANGED

Adjusted PoPs through the weekend given trends.

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 possible mid to late next week as we approach July 4th.

DISCUSSION

KEY MESSAGE 1...A WAA regime sets up across the area and persists into this weekend as troughing pulls away and high pressure becomes centered offshore. This regime will bring continued W-SW 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. The shift to temps staying below record continues, and with some consistency in this outcome now have decided to remove the climate section from the AFD. Despite us not reaching record heat, temps in the low to mid 90s and dewpoints in the upper 60s to low 70s heat indices could be 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, Saturday looks to be the best chance of needing any heat advisory headlines but will continue to monitor trends. 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. Strongest shortwave looks to impact the area on Sunday associated with an incoming backdoor cold front which would bring the best chances for precipitation. On Fri we may have multiple focuses for shower and thunderstorm activity with one being along an inland moving seabreeze Fri afternoon and the second coming in from the west Fri evening associated with the incoming weak shortwave. While moisture will be on the increase we will not be at our highest moisture level just yet on Fri so chances are still isolated for showers and thunderstorms along the sea breeze (15-20%). Further inland, some tstorms could develop along a thermal trough west of hwy 17, where chances are higher (15-30%). Will note while thunderstorm activity looks to remain sub- severe, we could see a few strong downbursts in the strongest storms with gusts up around 40-50 mph possible if they do develop.

As we get into 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 has increased the risk to Slight (2/5) for Saturday. It is worth noting that the severe potential may linger into the late evening/night. Even after the sun sets the WAA may continue to keep atmospheric profiles uncapped, allowing for convection persist. On top of the increased chances for showers and thunderstorms on Sat, increased chances for precipitation are once again possible on Sun as well (50-70%). Front looks to track from N to S Sun afternoon and evening providing thee 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 hazardous 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 /06Z FRIDAY THROUGH TUESDAY/

Pred VFR conditions expected through the TAF period, but another night of mainly clear skies and light winds will allow for good radiational cooling conditions which may lead to some shallow ground fog development late. There may also be isolated showers and thunderstorms that develop along the sea breeze and thermal trough Friday afternoon that could bring temporary sub- VFR conditions. Best chances are for inland terminals where VCTS has been introduced.

Outlook (Fri night through Tue): 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

Winds to turn to the SW this morning at 5-10 kts and increase closer to 10-15 kts Fri afternoon with gusts up to 20 kts. Seas generally remain around 2-3 ft as well into Fri night given the lighter winds. Boating conditions look to be rather pleasant today. Winds remain SW'rly Friday night and increase further to 15-20 kts with occasional gusts to 25 kts, though threat for SCA's remains low.

Outlook (Sat through Tue): Pinched pressure gradient and thermal gradient Saturday PM brings a risk of SCA conditions to coastal waters with SW gusts around 25 knots. Gulf stream showers and thunderstorms possible Sat/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.