Conditions Gradually Deteriorate

The 5PM advisory from the National Hurricane Center placed Hurricane Jose about 285 miles south of Nantucket. The storm was wobbling north-northeastward at just 8 mph – unusually slowly for a hurricane along / off the East Coast of the United States. The storm, which was quite ragged 24 hours ago but has shown signs of life today, has maintained minimal hurricane status today and will only slowly lose strength over the next day or two.

The going forecast remains relatively unchanged – but there are a few new details and questions to consider this evening:

Huge Variations in Rainfall Outputs from Some Computer Guidance

1) Core of the heaviest rain remains offshore? With the system expected to track a bit further south and east vs 24 and 48 hours ago, we could see the bulk of the heaviest downpours remain just barely offshore of the Cape. We are literally talking about a matter of miles here and there is still guidance which places the western edge of the heaviest rain on the Cape…but there is certainly a chance that we avoid a lengthy period of heavy downpours. Unfortunately, this is pretty much a wait-and-see / monitor-the-radar situation as small wobbles in the track and convective developments within the storm’s circulation will dictate the outcome. To give an example of the extremely tight gradient…one model yesterday cranked out an astounding 12 inches of rain at Chatham…and is now showing less than 1 inch! With that in mind, the “best” odds for seeing the highest rainfall totals are on the Lower and Outer Cape.

2) Strong winds linger into Thursday and Friday? There has been an undeniable trend in model guidance today to stall Jose southeast of Cape Cod and to even retrograde the system westward a bit. At the same time, the system’s wind field should expand as the storm continues to take on more hybrid and extra-tropical characteristics. This stall and retrograde, combined with an expanding wind field and a relatively tight pressure gradient on the northwest side of the storm, would keep (at a minimum) a gusty north wind in place through the end of the week. Interestingly enough, numerous products suggest that the strongest winds here on the Cape may not materialize until Wednesday night at the earliest…and may in fact wait until Thursday afternoon as the depth of the mixing layer increases and winds aloft strengthen

3) Heightened Concern for Beach Erosion / Coastal Flooding along Cape Cod Bay? Given the above-mentioned evolution to Jose, a lengthy period of strong gusty north winds seems inevitable and that should result in multiple rounds of beach erosion and likely some pockets of coastal flooding along the ocean-side Outer Cape beaches as well as north-facing shores from Plymouth/Sandwich to Brewster inside of Cape Cod Bay. Model guidance traditionally produces conservative wave height and surge forecasts…something to keep in mind as we go forward over the next 2 days.

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