Key MESSAGE 1, Heat and humidity will build into ENC from the north and west today into early next week. High impact heat and humidity is expected, as the peak of it will be during the busy 4th of July holiday weekend (Saturday through Monday) with highs expected to reach well into the 90s inland, possibly reaching 100 in some locales, with upper 80s to mid 90s beaches. The combination of the heat and humidity will push heat indices towards the 105-110 degree range or slightly higher this weekend. Overnight lows will also be warm due to the increased Tds, with MinTs around 80 near the coast, and mid 70s interior.
A Heat Advisory remains in effect for much of ENC today; only locations not included in today's advisory are Hatteras and Ocracoke Islands, and immediate coastal zones of the Crystal Coast, where the seabreeze circ is expected to keep advisory criteria just out of the forecast, but MaxAppTs in these zones will still be hot, in the 90s to lower 100 degree range.
The Extreme Heat Watch for Saturday has been upgraded and expanded with a Heat Advisory with today's afternoon package. Nbm's performance over the last two or three days has proved to be too warm across the bulk of the sensible Wx spectrum with NBM 10th and 50th percentile being closer to realized Max/Mins. Mixing during peak heating has been stronger than advertised in the NBM suite as well, with HiRes guidance performing better, showing Tds mixing down into the upper 60s and low 70s vs mid 70s NBM has in its solution. With little change in the pattern, have trended the forecast for the weekend in this direction which has resulted in slightly lower AppTs compared to earlier forecasts. Because of this, felt more comfortable upgrading the watch to a Heat Advisory, albeit a larger one compared to today. Sat's Heat Advisory is the same as today's with Coastal Onslow added. There is absolutely potential for some spots to hit the Extreme Heat Warning criteria of 110deg AppT, but I didn't feel that the conditions would be widespread enough or long enough duration to warrant the product.
Heat Advisory criteria will continue to be met into early next week with daily afternoon MaxAppT in excess of 100deg. The compounding nature of the daily heat with little overnight relief with MinTs trending warmer after the 4th, may warrant the issuance of an Extreme Heat Warning over the next couple of forecast cycles regardless of exact criteria being met. Those sensitive to heat and anyone planning on spending ample amounts of time outside this weekend into early next week should monitor the forecast trends. With the ridge of high pressure overhead, a cap will bring little to no shower or thunderstorm relief through Sunday.
KEY MESSAGE 2, Return to a pattern of increased shower and tstorms chances next week. A series of shortwaves, inland troughing, and a very slow moving backdoor front will eventually cross the FA mid-week leading to a diurnally driven, summer- time PoP forecast through much of the long-term period. Tue currently has the highest PoPs (50-70% TUE afternoon) when moisture peaks ahead of the front and a pair of shortwave troughs aloft traverse NE CONUS.
18z Friday through Wednesday VFR flight cats expected through the rest of FRI, though easing winds and humid low levels will keep patchy fog threat in play in the early morning hours for TAF sites that see the lowest winds. Oaj shows greatest potential and have continued TEMPO group mention of MVFR fog, but did reduce VIS from previous TAF issuance considering that IFR was briefly reported earlier this morning.
Outlook (Saturday through Tuesday): Dry weather is expected to prevail with pred VFR conditions through Sunday, but could see patchy fog during the early morning hours. Upper ridge breaks down Monday with shortwave energy bringing increasing chances for showers and thunderstorms and sub-VFR conditions both Mon and Tue.
Latest obs show S to SW winds 5-10 kt with seas 2-3 ft, and mesoscale circulations across smaller inside waters leading to light winds with highly variable directions. Thermal gradients continue to tighten some this afternoon and evening with winds increasing to around 10-15 kt with seas around 2-3 ft with up to 4 ft possible across the outer zones.
Outlook (Saturday through Monday): The Bermuda high remains dominant into the weekend with light winds 5-15 kt and seas around 2-3 ft. Bermuda high pulls offshore late Sunday into Monday with a front slowly dropping south across the Mid- Atlantic serving to tighten gradients a bit and expect winds to increase to around 10-20 kt and seas building to 3-5 ft.
Nc, heat advisory until 8 pm EDT this evening for ncz029-044>047- 079>081-090>092-094-193-194-198-203. Heat advisory from noon to 8 pm EDT Saturday for ncz029- 044>047-079>081-090>092-094-193-194-198-199-203. Beach hazards statement until 8 pm EDT this evening for ncz205. Marine, none.
