Torrential Downpours In The Northeast Today While Irma Churns Closer

Hello everyone!

Today’s US weather is once again going to be dominated by a cold front moving through the northeast. The cold front today won’t have quite enough energy to produce a widespread severe weather threat, but it will have more than enough moisture to drive some torrential downpours.

This is a map from the ECMWF model showing the amount of moisture in the air this afternoon. Generally values here above 1″ are supportive of heavy rains with values above 1.5″ indicating very high moisture content. As you can see, the coastal plain from Eastern Maine all the way down through the Mid Atlantic has more than enough moisture present to support heavy rain.

Today’s heavy rains will come in two rounds as two weak waves of low pressure travel northeast along the front. The first round will be in the early afternoon across parts of SE NY, Southern New England, and coastal ME/NH. The second round will follow later tonight and into tomorrow morning.

Farther south along the front, some strong to severe storms can’t be ruled out across parts of the coastal Southeast.

This map shows the amount of energy available in the atmosphere for thunderstorms. Notice how there’s very little if any energy over the Northeast and Mid Atlantic, but plenty in the NC/SC/GA area. This is why those regions will see this front bring some severe thunderstorm activity, but areas farther north will not. The main threat with these storms will be gusty winds and small hail, though a tornado cannot be ruled out.

Farther to the west, an upper level low moving into California will help fuel some strong thunderstorms in the northeast part of the state. 

Some of these storms could be severe with gusty winds and small hail.

What about Irma?

Irma strengthened yesterday evening to a Category 5 storm with 185 mph winds. That intensity continues today as the storm moves through the Leeward Islands. The environment around the system continues to support Irma maintaining this intensity as it moves west-northwest in the coming days.

What’s next for Irma? The same basic forecast I presented on Monday evening still applies. Irma will move WNW just north of Puerto Rico and Hispaniola before turning more to the west in the direction of Cuba. After making a close brush with the Cuban coast, the system will turn north. There’s still some uncertainty as to where that turn north will happen. As a result, there’s still some uncertainty with regards to the impacts Southern Florida will feel from the storm. However, even if Irma makes the turn north a little bit sooner than forecast and ends up tracking closer to Nassau than Miami, residents of Southern Florida should still be preparing for at least tropical storm conditions and impacts. I’ll have much more information tomorrow afternoon regarding Irma’s next steps.

Outside of the cold front discussed above as well as those storms in California, generally quiet weather is expected across the US as Irma is still a few days away. For more information on your local forecast, head on over to weather.us.

For more information on the local forecast for Maine and New Hampshire, check out my local blog post from this morning.

Jack Sillin is a weather nerd and forecaster who regularly writes for weather.us and 33andrain.com.

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  1. Spacecoast 09/06/2017
    • Jack Sillin 09/07/2017

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