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Showing posts with label tornado. Show all posts
Showing posts with label tornado. Show all posts

Monday, May 12, 2008

Expected and the Unexpected

Remember the Storm Page- Find the Tab or link to Full Web Site Above.
Mother's Day Forecast- Verified!

If this pattern was a few months ago- we would be digging out of historic snow. That's just a matter of timing. Sure the forecast was almost exact for 6 days leading up to Mother's Day- go back and check each post and you will see how the Canadian Model called this precipitation to move in. The rain began between 4pm and 6pm- and in just the last few hours of Sunday dumped a record 1.49" at BWI. That brings us to 2.66" for the month and all now surplus for the year. THE DROUGHT IS OVER! (As of 5am we had another 1.04" of rain)

That wind was something too: We average gusts over 40mph, but Ocean City wins with a gust to 66mph. Most of us had gusts between 35-50mph overnight. That is one mighty impressive Low (992mb), that had BWI's barometer down to 29.52" earlier today. Here is a live link to the Water Vapor Loop of the last 24hours. You can see the impressive circulation of what I see as a late winter like storm. Consider the snow drought and mild temperatures mid winter while much of the nation had record snow- that was the result of an active jet stream passing to our west and north. It is still quite active, and shifting east. In fact the whole jet stream is a bit south for May. Just a delay in the spring transition. In combination with May solar heating- the result has been deadly. Another round of tornadoes this weekend killed 22 (at last count). While it's been the most active tornado season in 50 years, again I see it as a rare jet stream, but the result of a moderate La Nina holding in the Pacific. Other's have been speculating- without surprise- that it something else... say Global Warming. I heard just that on ABC this weekend from an interview with two women called the Twister Sisters. I did a little background on these two, and you can find them at www.twistersisters.com. They have run a tornado chasing tour group. Are they just promoting their business? Somehow a cute name gets them a national interview, but they have little background if meteorology... They cited research guessing that Global Warming would allow more Gulf Of Mexico moisture to flow farther north and result in more tornadoes. That doesn't account for the low tornado years of 1999 and 2003. Jim Reed- photographer, was on GMA this morning also talking about trends. He has been tracking tornadoes for over 20 years. He believes there has been in increase in storm size and people getting caught out. That does lead credence to the mobility and spread of our population into places that were uncharted or sparse farmland just a decade ago...
Below are links to USA tornadoes since 1916. This brings up the debate of whether tornadoes have really increased dramatically or has our ability to track and confirm them improved. You'll notice the number of fatalities have dropped dramatically as well. Since 1995 with the completion of the current WSR-88D network, warning time has gone up from 5 to 20 minutes. But consider what else has changed.

  • Personal Video Cameras
  • Cell Phones (With Cameras)
  • Internet Use and transfer of images
  • Suburban sprawl... people live in more places that would go unnoticed in the past.
Tornado Reports
Tornado Fatalities

So what do you think? Please see the poll at the right and click your choice:

This is the pattern that should have evolved at the end of the winter. It seems rather common of many past springs, the pattern turns cool and damp too late. This is a demonstration of why so many in Maryland say we go right from winter into summer. The spring runs below normal in April and May, and as the jet lifts to our north by June- it brings prime heat with it, right on schedule.
Today, much like Friday- the redevelopment off of the coast wraps in some very cold northerly winds- keeping us in the low 50s or 20 degrees below normal. I would not be surprised if it stays in the upper 40s north of the beltway.
Look at this radar image saved from 6:34 this morning. Yup, that's snow in Altoona, PA (by the clock). I have to give credit to Tony Pann for calling this on Friday. He called me and pointed out the 850mb temps and 540 thickness forecast on the GFS model. I thought it was overdoing it. Wow! Of course it's not our forecast area, but impressive to have snow even in the higher terrain this time of year. A sign of the cold air generated bu this storm and reinforcing my forecast for this afternoon staying in the 40s in most spots.

Tuesday, April 29, 2008

Virgina Tornadoes! Frost Tonight?

Yesterday's storm gave us about 1 inch of rain locally, but that was nothing compared to the severe weather in south east Virginia. Here you can see the peak of the storms as captured around 4pm. If you see the map I posted in yesterday's blog- it was a strong cold front that sparked the storms.
Here is an example of wind sheer similar to what caused yesterday's tornadoes... Winds at the surface were from the south east, while the storm was moving cloud level winds from the south west to north west. A different direction and speed with height. That caused the wind to sheer or rotate with height. For the record, a Tornado Watch was posted for this region by The National Weather Service. A 75 mile path of at least 3 separate tornadoes straddled North Carolina and Virgina. Ironically this was the 6 year anniversary of the La Plata tornado. Today is the day that the NWS will survey the damage and confirm the strength. Early Doppler estimates of perhaps an EF 3- which would mean winds of 138mph-167mph.
For a comparison of the original Fujita Scale and the new Enhanced Fujita Scale- click here.

What I find most interesting, was that this morning, the cold upper level low was passing through Ohio, and brought snow to the mountains of West Virginia - see here at 6am. Due to this upper level Low, I am not sure we will clear out and get back to 60F today. I think clouds will likely hang on longer, and many of us will stay in the upper 50s. When we do clear out tonight, frost is likely just inland with temperatures back into the mid 30s... The sun will be back tomorrow.

Monday, April 21, 2008

Severe Weather Season Is Here....

Due to the storms yesterday and what is expected today- I will not be posting about the Chesapeake Health and Earth Day as expected. Sorry....
Yesterday's Tornado Warning was issue by NWS due to Doppler Indicated Tornado. There was none spotted at the time on the ground, but here are the Doppler Images showing what we look for.
Note: This image on the left is your standard return of rain intensity measure in DDZ you might see on TV or online. This was the image from Baltimore County around 6:20pm Sunday. The rainfall rates were over 1 inch per hour with small pea size hail in Parkton (account from a co worker). I've highlighted the central point of the storm and wind field, however the possible 'hook' on the south side in the rain free zone is a signature of rotation in a storm. Most tornadoes are in the rain free section on the south or southeast side of a storm.


This image is a different level showing the wind profile. The whole premise for Doppler Radar is measuring a frequency change as wind/rain, etc move towards or away from the radar site. Much like the sound Danica Patrick's car winning in Japan's Indy race. That change in movement is measure and shown here with wind away from the radar in red, and towards the radar in green. When they are stacked side by side, that indicates rotation and potential spin of a funnel cloud. You'll notice I did not say tornado yet since this is all at cloud level. There is no guarantee that it will reach the ground, and as of this posting (6am), I did not see any confirmation of touchdown.


I am working on placing the lighting tracker with Radars and Stuff, but until then I will continue to post a live image here:
In terms of rain, how about those giant drops? This type of environment will produce what appears to be larger drops as small hail generated in these storms will melt on the way down from the clouds. The wind turbulence will help to break up these drops, but some can hold together. There is a lot of moisture available, so rain amounts under these storms may exceed a few inches.
Our severe weather is all thanks to a cold upper level trough with this pocket of warm moist air underneath. That allows the freedom for this air to rise and quickly dump rain. The spin from the upper low (check it out on Water Vapor Loop)

Sunday, April 20, 2008

Tornado Warning "Doppler Indicated"

It was around 6:15 or so this evening when I first heard the warning. It was indicated by radar that the storm might be rotating, but that does not guarantee a funnel on the ground. Here is our lightning tracker which shows strikes over the past 30 minutes and any other indication on radar with rotation and storm centers. I have also posted an enhanced radar view. These colors are much more intense than our normal view- to help see the storm....
This is part of an upper low that will be stuck nearby for another day or two. For more mas go to the TV Graphics tab above (on my website view of this blog)
That's all I have time for now- be safe...