Should Mainers be concerned about Hurricane Irma?

Just in time for the peak of hurricane season, Irma, a Category 2 hurricane, continues to roll westward across the Atlantic.

As of late morning Friday, Irma was a Category 2 storm.

Peak of the Season

Meteorological summer came to a close on Thursday, so we are now entering the peak of hurricane season. Of course, storms have and will hit New England before and after this period, but the odds are greatest over the next 10 days.

A hurricane hasn’t hit in over two decades

It’s important to keep in mind that the odds of a major hurricane hitting New England are quite small.

The last hurricane to reach the shores of the region was Bob back in 1991, and the last major, Category 3 storm to strike was Carol on Sept. 1, 1954. The winds in that storm, 63 years ago, were actually stronger than those experienced in Texas when Harvey made its first landfall.

It’s quite uncommon for a storm to still have hurricane strength upon reaching Maine. Donna was a Category 1 when it entered the state back in 1960.

Heavy rain, but not 50 inches

Aside from the wind, tropical systems can bring tremendous rainfall.

Images from the Gulf Coast showing the unprecedented amount of water beg the question whether the torrents witnessed there could happen here? The short answer is no.

Meteorologically, even a stalled system is highly unlikely, if not close to impossible, to bring us the rainfall we have seen in Texas and Louisiana. The reason: Conditions created by the proximity of the Gulf of Mexico and the warmth of those waters simply don’t exist here.

While we can pretty much rule out getting 4 feet of rain here, we should take note that major hurricanes do hit New England.

What about Irma?

It’s very early in the forecasting game for Hurricane Irma.

While this storm is certainly getting itself better organized, we don’t know for sure how strong it will become.

Some models ramp her up to a Category 4, but not a 5, which is the strongest, while other models predict something less intense.

As of late Friday morning Irma had weakened a bit. This is expected as these storms undergo different cycles of strengthening.

The eye, which is the calm center of the storm, is surrounded by the eye wall, which is the most intense part of the storm. This undergoes various configurations of weakening and strengthening during a long-track hurricane such as Irma.

Late this weekend the storm will be above warmer water, one reason for a forecast of a stronger system.

Irma is continuing a path west toward the islands in the Caribbean.

The next question is where this storm will track in the coming week to 10 days and whether it could affect the United States. Here again the models offer numerous possibilities for the eventual path of Irma.

Various models take Irma into different spots of the south Atlantic next week.

How hurricanes move

Hurricanes are typically steered by pressure systems around them and most notably by high pressure typically found in the Atlantic. Tropical systems are forced to go around these highs. The exact placement and strength of the high as well as its interaction with other weather systems to the west and east create a funnel of flow for the hurricane.

The Bermuda high acts as a steering tool for tropical systems.

The image above is an average. In actuality, the high pressure area changes daily. The lack of strong steering currents last week is why Harvey meandered so long around Texas.

Looking to the past

Back in 1960 Hurricane Donna crossed Long Island, New York, and then pushed from southern New England into Maine. This storm brought 77 mph winds to Portland.

Donna reached Maine as a minimal hurricane in 1960.

Irma’s track

Assuming Irma remains a hurricane, it will likely affect the islands of the Caribbean next week and then move toward the United States.

Currently, it appears the storm will curve up along the East Coast, hit the East Coast or make a sharp right turn and head back out to sea. It’s all going to depend on how the weather systems evolve in the coming five to seven days, and it will take that long to really have a good idea if this is truly a threat to us or not.

The position and strength of high pressure over Hurricane Irma and the jet stream over the United States will determine the ultimate path of this storm.

There’s little doubt there will be a lot of interest in Hurricane Irma over the next week. Her affect could be significant or she could be just another Atlantic storm with little impact.