Isaac is now making its way through the Midwest bringing clouds, rain, thunderstorms and very muggy conditions. The rain bands around the Miami Valley are rather scattered but I expect those to organize a little more for Sunday.

Here’s where what’s left of Isaac is right now.  You can see a spin in the clouds from the area of low pressure now centered near Missouri and Illinois.

This former tropical system is making it “feel” tropical around here.  Dew points (that’s the measurement of how much moisture is in the air) are in the upper 60′s and lower 70′s.  We usually don’t see values this high very often so that’s why it “feels” so muggy outside.  (on a side note:  The reason I am showing dew points instead of relative humidity is because dew point is a much better measurement of how muggy it feels.  When dew points are above 60 you’ll feel the high humidity.  This is a perfect case because the relative humidity today was 61% at 5pm.  This is why it’s important to use dew point and not relative humidity when talking about how muggy it is)

Basically it feels “gross” out there.  It’s not going to get any better this weekend either.  Expect the high humidity to continue through Monday.  These high dew points tell us there is a lot of moisture in the air and a lot of fuel for rainfall.  We are going to see quite a bit of it over the holiday weekend.  While the exact timing and placement of the rain bands from Isaac are going to be hard to pin point Sunday is going to be a better day to pick up significant rain.  Keep the umbrella handy and have a back up plan if you have any outdoor activities.

I think the main threat from Isaac will be locally heavy rain.  The risk of severe weather is going to be low for the weekend.

The muggy and rain continues for Labor Day as well.  Although the rainfall is going to be more scattered in coverage.

Throughout the next few days we have the potential to pick up anywhere from one to as much as 2.5 inches of rainfall.  This will really help some of the areas in the Miami Valley that have been seeing very dry conditions this summer.  As always with heavy rainfall there’s the potential for flooding.  However because the rain is  going to be over a few days, the ground is dry, and local streams are low it doesn’t look like we’ll see flooding issues.

One important note – I have had many questions asking if Isaac will bring the strong winds we saw with Ike.  The answer is no.  These are two different systems.  We saw strong winds with Ike but with Isaac we’re going to see just heavy rainfall.  Here’s a great graphic the National Weather Service Office in Wilmington put together explaining the difference between the two.

Keep the umbrella handy this weekend and try to stay dry!

Tara
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