Tropical Weather Resources

Here are a few of my favorite sources for tracking tropical weather:


"Official" Information & Advisories:
The National Hurricane Center, of course...


Satellite Imagery:
Cooperative Institute for Meteorological Satellite Studies


When the storm is impacting Texas, here is a good visible satellite image source, courtesy of the Texas Center for Environmental Quality.


Model Data:
Kind of a "one stop shop" for tropical weather data, including model forecasts, the Weather Underground's Tropical Weather Invest Page.


Radar Data:
GRLevel2 and/or 3 are, of course, excellent.  If you don't already have the program(s), download the full trial version here.


Once you're using GRLevel2 and/or 3, I highly recommend subscribing to the additional resources of Allisonhouse, which include hurricane model data, forecast track data, model data and hurricane hunter aircraft data that can be overlain right on the radar imagery!  Here is a sample image of what I'm talking about:

Center of Alex Nearing Mexican Coast

Above is the WSR-88D (NEXRAD) radar image from the Brownsville, TX (KBRO) site taken a few moments ago.  You can clearly see the eye of Hurricane Alex about 30 miles East of the Mexican Coastline.  This same position is about 96 miles South/Southeast of Brownsville, TX.  

As of the 6pm Central Time National Hurricane Center Advisory, hurricane force winds extended out about 70 miles from the center of the storm.  This means that hurricane force winds would impact land up to about 20 miles South of the Texas/Mexico border, on the present track.  Tropical Storm force winds extend out from the center by just over 200 miles, and tropical storm force wind gusts have indeed been occurring across far South Texas during the last couple of hours.

So far for deep south Texas, very heavy rains have been the main story, along with some isolated wind damage reports:

The image below is the Brownsville radar estimate of storm total precipitaition thus far, through 6pm local time.  The dark purple areas show rainfall estimates of 9-10 inches, while the lighter purple areas show rainfall estimates of 7-9 inches:

  

Widespread, sometimes heavy, rains will continue across far South Texas through much of the night and into Thursday.  This will undoubtedly lead to flash flooding in many of the same areas.

Further North across central and the remainder of south Texas, rains have been tempered a bit today by the concentration of activity further South near the center of Alex.  As the system moves inland tonight and tomorrow, additional moisture and energy is likely to flow Northeast into the remainder of the region, which will result in increasing rain chances there as well.

Alex Nearing Hurricane Strength

Despite the normal computer model guidance flip-flopping of the last few days, the general trend of expecting the center of Alex to move across Northern Mexico (as reflected in my original post a few days ago) appears to be coming more certain.  The ridge of high pressure that was expected to build over the central & southern U.S. is indeed doing so, which will turn Alex more toward the West/Northwest rather than North/Northwest track over the next 24-36 hours.  


The latest National Hurricane Center forecast track reflects the above thinking, with the center of the storm expected to strike land in Northern Mexico sometime before 1am on Thursday morning, central time:

It would be an error to focus solely on where the center of the storm will make landfall, as its reach will extend far from the center.  Certainly the strongest, (likely hurricane force by that time), winds will take place near and immediately surrounding the center, however tropical storm force winds currently extend outward over 170 miles from the center.  On the current forecast track, this means that widespread tropical storm force winds can be expected well into the Rio Grande  Valley of far South Texas.


Alex is currently still classified as a tropical storm.  I suspect he will be upgraded to a hurricane by the next advisory this evening.  Another Air Force Reconnaissance flight will pass through the storm around 7pm Central Time.  The data obtained by that flight will likely determine an intensification to hurricane strength, based on what we're seeing on satellite imagery (like the one at the top of this post). 


Alex will also spread heavy rainfall well into central and south Texas throughout the end of the week.  Summer rains from tropical systems can be both beneficial and hazardous, depending on how much flooding takes place as a result.  It is literally a mixed blessing.

Tropical Storm Alex

Above is a recent satellite image of Tropical Storm Alex, with the 1pm CDT National Hurricane Center (NHC) statistics superimposed in the upper-left hand corner of the image.

Now that Alex has formed, the $64,000 question is, of course, where will he go?  Well, the Yucatan Peninsula is obviously directly in Alex's path at the movement, with the system likely to traverse that land mass from about 8pm this evening through 8pm Sunday evening.  The land mass will quickly result in Alex weakening back down to depression stage after making landfall, but with plenty of warm, Gulf water on the other side, he will likely reintensify upon emerging back out into the Gulf on Monday.  In fact, most of the models have the system reaching hurricane force out over the Southwest Gulf early next week.


Below is the forecast track of Alex as indicated by the latest computer model runs (at total of 7 different computer model forecasts are included, indicated by the color coded legend at the top of the map).

As you can see, the "mean" (or average) track is toward the West/Northwest.  Not one model is currently forecasting a "direct hit" on Texas (the GFDL model does brush the center of Alex on the far southern tip of the state late Wednesday night or early Thursday morning).

The main feature that will determine the track of Alex at the moment appears to be the ridge of high pressure that has dominated the central & southern U.S. weather pattern over much of the last week to 10 days.  The ridge is currently undergoing some weakening/transitioning, but is forecast to regain a foothold on the region again by Tuesday.  If this expectation occurs, then the above forecast tracks of Alex having more of an impact on Mexico rather than the U.S. are likely to come to pass.  


Needless to say, if you live in South Texas or Mexico, you'll want to keep a close eye on the progress of Alex over the coming days.

Tornadic Supercell in Nebraska Panhandle

The above image was taken by the Cheyenne, WY (KCYS) NEXRAD a moment ago.  It's in reflectivity mode, which shows all precipitation echoes being sent to the radar (rain, hail, etc.).

This storm is also rotating, as shown by the strong "mesocyclone" on the Storm Relative Velocity (wind motion) image taken at the same time, below:

Note the strong motion toward and away from the radar associated with the storm (just Southeast of Harrisburg).  This is what is referred to as a mesocyclone.  Remember that green/blue colors are motion toward the radar while red/orange colors are motion away from the radar.  The radar is located just off of the lower left corner of the screen.  

Oh Yeah...I Almost Forgot...

Today is the first "official" day of summer.  Forgive me if I don't seem too excited, but it's been 95+ degrees with a heat index of 100+ degrees for what seems like the last month here in southcentral Texas, so I guess my senses already thought we've been there and done that...


None-the-less, the Summer Solstice took place at around 6:30 local time this morning.  Folks near the Arctic Circle up in Alaska won't see the sun set for the next 4 days...hence the nickname "land of the midnight sun".  I haven't seen that in person, but sure would love to some day...

Tornadic Storm in NW Kansas

Above is the Storm Relative Velocity (wind motion toward & away from the radar taking the storm's movement into account) image taken from the Goodland (KGLD) NEXRAD radar a few moments ago in Northwest Kansas.  Can you locate the mesocyclone about 13 miles South of Atwood, KS?

See below for a hint:

Remember, green is indicating wind blowing toward the radar, while red is indicating wind blowing away from the radar.  The radar is located just off the bottom left corner of the screen in these images:

Look even more closely within the mesocyclone and you can see Tornadic Vortex Signature, or where a tornado is most likely taking place on the ground:

So far there have not been any ground truth reports of tornadoes South of Atwood, but with the above signature I am confident that something is going on.  This is mainly in a rural area, so whether or not actual reports will be received remains to be seen.