DAYS 1-5 (AUGUST 4-8)
As far as “action” goes, this forecast is front-end-loaded. Today and this evening will be our impacts from Isaias. The thinking has not really changed since yesterday. While the system, according to NHC, returned to hurricane strength before making landfall in SC yesterday and moving up across the eastern Carolinas overnight, it has weakened to a tropical storm and will continue to slowly weaken while at the same time starting to undergo transition to a post-tropical system (or return to a cold core low pressure area) as it tracks north northeastward all the while accelerating. This track will take the center of the low across NJ, southeastern NY, and far western to northwestern New England during this evening. It’s known, but I will remind you, that the wind field around these systems tends to expand as the storm loses tropical characteristics. Another general rule of thumb is that the heaviest rainfall amounts occur west of the center with a more showery/windy eastern side of a northward-moving storm system. All these rules generally apply here. I think it’s important to note that the absolute strongest wind gust potential will be coming as what appears to be a single band of convective rainfall (downpours & possible thunder) sweeps across the region from southwest to northeast early this evening. Yes it will be breezy to windy before it and after it, but those convective cells are what can bring down your strongest winds to the surface, and therefore can be where you find the most significant pockets of wind damage. These systems also bring their own wind sheer along with them and those convective cells can easily rotate, sometimes enough to produce brief and (relatively) weak tornadoes. It goes without saying that even “weak” tornadoes can cause significant localized damage. So we will need to be on the watch for this. But as quickly as the maximum part of this event will be underway for us, it will be gone, and the overnight hours will feature less wind, but still a gusty breeze, and an opportunity to look at the stars and moon as the sky clears. With the low in eastern Canada and moving rapidly away on Wednesday, expect a rather nice summer day here on Wednesday. If there is any damage cleanup to be done it can proceed without any further weather issues. High pressure builds in, centered just to the north of the region, with a nice day, air temperature modified by an easterly wind flow, on Thursday. A frontal boundary not too far to the south will edge northward far enough on Friday for more cloudiness, and maybe a bit of South Coast shower activity. This may linger into early Saturday before high pressure wins the battle and clouds retreat for a nice start to the second weekend of August.
TODAY (THROUGH EARLY AFTERNOON): Mostly cloudy. Passing rain showers possible. Increasingly humid. Highs 76-83. Wind SE-S 5-15 MPH except increasing to 15-25 MPH late afternoon, strongest South Coast.
MID AFTERNOON / EARLY EVENING (ABOUT 3PM TO ABOUT 7PM): A band of showers, some heavy, and a risk of thunder, moving southwest to northeast across the region. Very humid. Temperatures cooling slightly to 70-77. Wind SE-SSW sustained 15-25 MPH interior and 25-35 MPH coast. Maximum wind gust potential generally 45-60 MPH, favoring coastal and higher elevations, but can occur in isolated locations interior with any heavier showers/storms.
TONIGHT: Partly cloudy to mostly clear. Humid. Lows 65-72. Wind SW 10-20 MPH, higher gusts.
WEDNESDAY: Sun and passing clouds. Less humid. Highs 82-89. Wind W 10-20 MPH and gusty early, diminishing to 5-15 MPH.
WEDNESDAY NIGHT: Clear. Lows 62-69. Wind W up to 10 MPH.
THURSDAY: Sunny to partly cloudy. Highs 80-87, but turning cooler in some coastal areas during the afternoon. Wind variable up to 10 MPH with coastal sea breezes.
THURSDAY NIGHT: Increasing clouds. Lows 60-67. Wind E to SE under 10 MPH.
FRIDAY: Mostly cloudy. Slight risk of showers South Coast. Highs 77-84, coolest coast. Wind SE up to 10 MPH.
FRIDAY NIGHT: Mostly cloudy. Risk of showers South Coast. Lows 63-70. Wind SE up to 10 MPH.
SATURDAY: Early clouds and a shower risk South Coast, otherwise partly to mostly sunny. Highs 78-85, coolest coast. Wind NE 5-15 MPH.
DAYS 6-10 (AUGUST 9-13)
High pressure brings fair and warm weather August 9, then shifts to the south with an increase in humidity and a risk of showers/t-storms during the August 10-13 period, highest risk around August 12-13 with a frontal boundary in the region.
DAYS 11-15 (AUGUST 14-18)
This looks like a mostly dry period with high pressure centered north of the region at first, keeping temperatures moderate, then high pressure shifting to the south later as upper level high pressure builds, increasing the chance of hotter weather returning.