Wednesday, September 30, 2015

Hurricane Joaquin + Major Flooding Possible

I try not to write to much "inside meteorology"on this blog since it is for the public-at-large. However, meteorologists are dealing with an extraordinary situation this evening so I hope a little "insider" information might be interesting.

Normally, at this point in a major tropical weather system, the "models" (computer simulations of the future state of the atmosphere) start coming together geographically. Today, they are doing anything but converging with regard to Hurricane Joaquin. Courtesy of Dr. Ryan Maue, here is a plot of all of the different model solutions. It is breathtaking in its breadth.

Nevertheless, meteorologists don't get to say, "the models were bad" as an excuse. You expect us to give us our best forecast regardless of any problems we may have to face. So, here goes:

Flooding

This is a huge issue. As much as 14" inches of rain have fallen in western Virginia in the past seven days (see map below). The red areas have received more than five. So, given the wet ground, if high winds occur, trees will be uprooted at speeds much lower than usual. Plus, given these rains, some rivers are already running high.

Here is the National Weather Service's smoothed rainfall forecast for the next 7-days.

Here is a rough estimate of the rainfall if, for example, Joaquin makes landfall in North Carolina and then stalls over South Carolina as one of the computer models indicates. Do not take this as a forecast of the hurricane's path! My point in showing this is that if the hurricane adds to the rainfall amounts, an area will likely have more than a foot -- with catastrophic flooding possible.

So, if you live:
  • In a flood prone area or near a small stream
  • If you live in a 100 year flood plain
  • Or, if you live near a major river in the area labeled "heaviest rain region"
please think about the following preparations:
  • Plenty of extra cash.
  • A full tank of fuel for your vehicle.
  • Freshly refilled prescriptions.
  • Valuables gathered together so they can be quickly put into the trunk so you can leave quickly.
  • A place to go: A relative's home on high ground, a motel, a public shelter, etc. If you go to a hotel, have a reservation. You may wish to consider an "extended stay" type of hotel.
  • Be prepared to put valuable items you cannot take with you on top of tables, on the second floor, or in the attic to hopefully protect them from floodwaters. 
  • If you evacuate, turn off the gas, water and electricity.

Hurricane Joaquin

The pale blue is the National Hurricane Center's official forecast as of 5pm Eastern time.
I have added (between the orange lines) where I believe the higher risk of landfall may reside. However, this entire forecast is fairly low confidence. 

The storm will likely be Category 1 or, possibly, a minimal Cat. 2 in terms of wind speed at the time of landfall based on what we know now.

What Are We Doing Now to Reduce Uncertainty?

The National Weather Service -- a government agency that is one of the few that produces far more value than it takes in in tax dollars -- is flying its Gulfstream aircraft in the blue area and dropping an instrument package at each of the squares. In addition, the Hurricane Hunters are making recon flights into the storm. Add that to doubling the number of weather balloons being launched and, hopefully, we'll have much more confidence by tomorrow (Thursday) morning.,

Thanks for reading. There will be more updates as I get more information.

No comments:

Post a Comment