US says goodbye Harvey and hello Fall, Chilly 10 days ahead in East! Watching Irma

Amazingly, we’ve been talking about Harvey for a solid week now and he’s finally lifting and fading but not without flooding parts of the TN/OH valleys.

Credit: weather.com

Credit: Tropical Tidbits

Credit: weather.com

While Harvey finally begins to leave the playing field, down comes one of two waves of Canadian chill which will certainly bring a taste of fall to the East.

While Harvey joins forces with a SE bound cold front which will enhance the cool Eastern trough this weekend with a stronger push next week, the Great Basin continues to enjoy summer.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

GFS ensemble 5-day mean 2m temp anomaly.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

While less extreme, even the 11-15 day is cool and this takes us out to the 16th.

Credit: Tropical Tidbits

US nervously watches Category 3 Irma in Atlantic

Harvey may be on his way out but unfortunately more trouble may be on the way. Now a powerful Category 3 and likely to become 4, Irma is making a beeline for the Leewards and most long range models take this deepening, dangerous system through the Caribbean and towards the Southeast US in 10-14 days… There’s a lot of uncertainty however and at least we’ve time with this one.

Piece from weather.com

Clues to East Coast Danger or a Sigh of Relief

There are some overall pattern clues for which meteorologists look to ascertain the overall threat to the East Coast from a hurricane approaching the area.

Scenario A: East Coast Danger

The Bermuda-Azores high is usually the primary steering wheel for Atlantic tropical cyclones, particularly those from Africa to near the Caribbean Sea.

When this high is strong and expansive in west-to-east extent and/or there’s little or no southward plunge of the jet stream anywhere near the eastern U.S., an approaching hurricane would be steered westward into the Caribbean Sea, Gulf of Mexico or East Coast.

In the case of Hurricane Isabel in 2003, there was actually high-pressure aloft over New England that helped steer Isabel into the East Coast.

(MORE: Beware of ‘I’ Hurricanes)

The typical pattern in place for an increased threat of a U.S. East Coast tropical cyclone landfall.

Scenario B: East Coast Relief

Conversely, if the Bermuda-Azores high is weaker, centered more toward the Azores and/or there’s a sharp southern plunge of the jet stream near the eastern U.S., the hurricane would follow around the west side of the high and curl safely off the East Coast, though sometimes putting Bermuda or parts of Atlantic Canada at risk.

One recent example of this was mid-August’s Hurricane Gert, which became a Category 2 hurricane but “split the uprights” between Bermuda, the U.S. East Coast and Atlantic Canada.

The typical pattern in place for a diminished threat of a U.S. East Coast tropical cyclone landfall.

In reality, the forecast is often more complicated, and not neatly sorted into either of those scenarios.

Furthermore, an East Coast relief pattern (scenario B) days before the hurricane arrives may evolve to one that steers it toward the coast (scenario A) by the time the hurricane gets near. This can happen if the eastern U.S. jet stream dip moves out or weakens without helping to turn the hurricane away from the coast.

The takeaway is that all residents along the East Coast and Gulf Coast should check back with weather.com or any trusted source for weather information to get the latest on Irma.

As the days go by, uncertainty will narrow and we’ll be able to pinpoint first whether Irma will impact the U.S. and, if so, when, where and how severe the impacts may be.

(MORE: Retired Atlantic Tropical Storm and Hurricane Names

In the meantime, now is an excellent time to develop or refresh your hurricane plan. The Federal Alliance for Safe Homes has an excellent site to help.

FEATURED IMAGE CREDIT: 

Tags: ,

Follow us

Connect with Mark Vogan on social media to get notified about new posts and for the latest weather updates.

Subscribe via RSS Feed Connect on YouTube

Leave a Reply

Top