Throughout this afternoon and early this evening, Bertha was not really discernible within the east coast trough. In the most recent hours a new plume of thunderstorms has gone up off the coast of the Delmarva peninsula, which suggest that Bertha as we know is still kicking. That time is slowly coming to an end as the vorticity (or spin) is becoming entrenched into the cold front off the east coast. Also notice the low pressure center to the southwest of Bertha in the analysis below. That low was the low the NHC isolated as the possible system that could have absorbed Bertha a few days ago. That obviously did not happen. That system did however bring record rainfall (~7″!) to the Naples area in recent days.

Getting back to Bertha, our shielding trough will likely absorb this tropical storm in roughly 24 hours or slightly more. That will – in a technicality – end Bertha’s life as a tropical cyclone. Let me stress that impacts will remain the same as Bertha moves past Canada. Bertha has spread high seas and rip currents all the way to the coastline from the Carolinas northward. These seas have gotten up to 8 feet high in some spots even closer to shore. Surfing is not recommended in these seas, and they can be life-threatening. These seas will likely follow Bertha as it moves toward the northeast this week. Bertha will be passing Nova Scotia tomorrow and Newfoundland on Thursday. Bertha…or what ever is left of this system…will reach Great Britain over the weekend likely on Sunday.

Intensity is expected to remain a near constant 50 mph, and thus I will not be including the current numbers on Bertha at 11pm unless there are significant changes. Please see the NHC advisory for the latest at http://www.hurricanes.gov

Impacts: 

• Gusty winds and rain are possible on the eastern end of Newfoundland in Canada, however most of the impacts will be over the water. Boating concerns should keep this in mind.
• Waves will increase on the east coast to 5-8 feet well off the coast of New England tomorrow. 4-8 feet waves are possible on the coasts of eastern Canada peaking on Thursday. Rip currents are possible north of the Delaware coast into New England through the weekend.

Active Times Ahead in Paradise

The above image is of Annular Major Hurricane from the ISS webcams. I always love to see pictures of tropical cyclones from the ISS because of the shear detail we get. This particular image shows the very circular eye and the stadium surrounding it, as well as the sun being seen setting on the southern side of this eye.

Microwave imagery of Hurricane Iselle taken during the afternoon.

Enough of my drooling! Hurricane Iselle is beginning to weaken as it has hit both shear and dry air. Usually when a hurricane hits those two things they begin to fall apart, but because this system was annular upon impact it has been resilient. In the image above, you can see that dry air has reached the eye of Iselle on the southern side at least at the mid to upper levels. Although shear has been lessening very recently, the intensity forecast thankfully is for Iselle to weaken as it approaches the Hawaiian islands. That being said Iselle is still expected to be a moderate tropical storm as it reaches the Big Island. A tropical storm watch has been issued for that island. Just as we see in the Atlantic, an area of high pressure is also present in the Pacific, and that steer and accelerate Iselle toward the WNW over the next 3-5 days. Iselle will be reaching the longitude of Hawaii on Thursday afternoon, and impact will move westward into the weekend.

Tropical Storm Julio is the second possible hit in the Hawaiian island chain as forecast by the NHC. Fortunately, the track of Julio is a bit farther north than Iselle, but this track can and probably will change in one direction of the other. The NOAA Hurricane Hunters are flying missions around Iselle today and that data will help the forecasting for both Iselle and Julio. Julio will be traveling through waters that are cooler than the waters that Iselle traveled through and conditions are not expected to be as good. The NHC currently forecasts a max sustained wind at 85 mph later this week, well before any impact on Hawaii.

The above graphic shows the combined probabilities of winds reaching or surpassing 40 mph over the next 5 days for both Iselle and Julio (and Genevieve well to the west). These probabilities will increase as both systems get closer to the island chain.

Julio will be reaching the longitude of the Hawaiian islands on Sunday or Monday as a moderate tropical storm.

Impact Summary of Iselle and Julio: 

• Wind: Winds greater than 40 mph will reach the Big Island on Thursday and move westward as Iselle moves WNW. Gusts of hurricane force could occur on the mountain peaks of the Big Islands at that time. Julio could bring similar winds again on Sunday and Monday, again moving through the island chain from east to west.
• Seas: Rough waters will be commonplace east and southeast of Hawaii through Monday with high seas moving through the islands starting late Wednesday and continuing through early next week. There may be smoother waves in between these two storms.
• Heavy Rainfall: Rainfall of a couple of inches is possible Thursday and Friday on the Big Island and these rains will move westward toward the end of the week from Iselle. Mudslides are possible in the mountainous areas. Flash Flooding is possible, and the entire state is under a flash flood watch.
• Tropical Storm Watch: Hawaii County (the Big Island) …for winds of 40 mph or greater possible within 48 hours.

I will be watching all three systems as they evolve. Have a great night!

–Jonathan, @JonathanBelles