Monday, August 28, 2017

Tropical Storm Harvey and the Florida Blobette: August 27, Update A

Jumping right in today…

Tropical Storm Harvey
The on-going saga… the severe flooding and tornados in Texas today will continue as he is still hanging out in the area.

He is currently at 28.8N, 96.6W, heading ESE at 3mph – so he has started to move, but very slowly. Because it is night-time, you can barely see his center of circulation in this infrared satellite imagery:
But what is quite clear is the area of thunderstorms and tornados in the dark orange and red areas, including Houston. He is officially barely a Tropical Storm with winds of 40 mph (TS range: 39-40mph) and a central pressure of 1000mb. I would now agree with the Tropical Storm status, but I think he is stronger than ‘barely a Tropical Storm’. The circulation (vorticity) in the upper level of the troposphere has finally started to wane so he is no longer a hurricane. But it is really very strong in the lower half of the troposphere, which indicates to me that he is still a pretty robust Tropical Storm:
Lowest level vorticity (850mb): 
Mid-level (500mb):
 Upper-level (200mb):
The NHC forecast track has him moving over water again, so we can continue to expect more rainfall and possibly more strong thunderstorms. The flooding is enormous – not only from the rain, but along the coast the storm surge reached around 3ft in a number of places. The highest storm surge that I saw from Tides Online was again at that Manchester tide-gauge at the top of Galveston Bay… where waters reached almost 10ft above normal!!
<Technical Alert!> A bit about Tornadoes: If you are under a tornado warning, I hope you have a siren or radio that will alert you!  But for anyone who is not in the area and is concerned and looking for information on Tornadoes, I would look at NOAA’s National Weather Service radar first. From this site, click on the ‘dot’ that is closest to the region you are interested in, and you will get the radar image for that region. These images will have boxes indicating the areas that have a warning (a warning is more imminent activity and is issued when a tornado has been seen either in person or on the radar; a watch is where there is some potential of activity during the watch timeframe but a tornado has not yet been seen). For the Houston area (for example), you can see a band of very strong thunderstorms (red) and boxes that are in red, showing where there is a Tornado warning:

I also like to check the text which will tell me which county in particular is under that warning. For that, I got to NOAA’s Weather Ready Nation website, and under the map are a list of warnings and watches. Clicking on the ‘Tornado warning’ will lead to the textual information where you can gather more specific information for that location. These are updated very frequently, so make sure you refresh the page. For the Houston/Galveston area:

For general information about tornadoes and what to do in the event that you are under a warning, there are many resources, including the Department of Homeland Security’s Ready tornado website. <End Technical Alert>

As always, please stay safe out there and listen to your local emergency managers and authorities. More on Horrible Harvey tomorrow! 

Florida Blobette
There hasn’t been too much change here. Florida got a drop or two of rain today again:
But most of the convection is streaming off to the northeast because of wind shear. The vorticity (circulation) is still not very well developed as you can see in the 850mb vorticity map above (it is elongated instead of the circular sort of shape that Harvey has), and there isn’t much in the middle troposphere yet (500mb) – again, compared to Harvey there is nothing, but compared to yesterday, it does look like it is slowly forming.

Officially, it is stationary and the ‘center’ is at 30.3N, 81W (just offshore from Jacksonville). Central pressure is 1007mb, winds are 30mph. We may be looking at the future TS Irma if the wind shear dies down and she gets her act together.

That’s it for this crazy weekend kids.

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DISCLAIMER: These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know. 

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