Archive for February 24th, 2012
Weather observations inside tornado
A long time friend and blog reader, Wally Coker, has been keeping 1-minute resolution observations at his house in Clay, just off I-59/Deerfoot Parkway, for several years. His station ID on the mesonet was KC4ANB. Since getting 1-min data is tough in the short-term, I have sometimes asked Wally for his data, and he always obliges. I have used his data in blog posts, conference talks, etc.
Wally’s home was hit by the Center Point-Clay-Trussville tornado of Jan 23. His house is pictured below. Fortunately, his family was safe.
His Davis instruments weather system was wireless, and continued taking wind observations until his roof came off the house around 414 am. Apparently, the barometer is inside the weather station inside his basement, so it took readings for a few more minutes (it and computer must have been on battery back up and kept running until rain water came in). His highest observed 1-minute average wind speed was 53 mph. His highest recorded gust was 79 mph according to an internet site he was linked in to, but given the damage I would say it got a lot higher than that when the roof and the anemometer left.
Here is a trace of pressure and 1-minute average wind speed, then a trace of temperature, both at Wally’s house.
The rapid drop in pressure began even before the tornado arrived, but got worse when it did. This drop in pressure is due to the rotation in the mesocyclone and then the tornado…centrifugal force literally throws air out away from the center of the rotation, just like you get pushed to the outside of the curve in a car. The wind averaged 53 mph for the minute ending at 4:13 am, then dropped and went away.
Interestingly, the temperature suddenly rose 2 or 3 degrees as the tornado passed by. This could be an electronic problem with the sensor due to debris, etc. But, some have suggested that there are occasionally downdrafts in the middle of a tornado that can actually warm the air right in the middle…so maybe it was real.
Cool Weekend Ahead
**No afternoon Weather Xtreme video today**
ACTIVE WEATHER TO THE EAST: Big storms continue over the eastern third of the U.S. this afternoon, where tornado watches are in effect… here is one of them…
TURNING COLDER: The sky will clear across Alabama this evening, and by daybreak tomorrow we will be down in the 32-35 degree range with a fair sky and light wind. This will kick off a dry but cool weekend.
TOMORROW AND SUNDAY: We expect maximum available sunshine tomorrow with a high between 56 and 60 degrees. Sunday morning will be cold again with a low in the 30s, but we rise into the low 60s by afternoon with a partly sunny sky.
NEXT WEEK: The 12Z GFS looks pretty dry Monday, and we turn warmer with a high up in the mid 60s. Then, we warm up in a big way through mid-week; the latest MOS is printing a high of 70 for Tuesday, and 80 for Wednesday. Showers will begin to form Tuesday, but the main rain/storm day will be Wednesday, and with a high near 80 needless to say we will have to monitor that one for signs of severe weather potential as we get closer.
And, still no sign of any major late season cold snaps through the next 15 days. You can see the morning Weather Xtreme video for more details and graphics.
WEATHER BRAINS: Don’t forget you can listen to our weekly 90 minute netcast anytime on the web, or on iTunes. This is the show all about weather featuring many familiar voices, including our meteorologists here at ABC 33/40.
CONNECT: You can find me on all of the major social networks…
I had a great time today visiting with the kids at McElwain Christian Academy…. be looking for them on the Pepsi KIDCAM today at 5:00 on ABC 33/40 News! Brian Peters will have the video updates over the weekend…. my next one will be posted early Monday by 7:00. Enjoy the weekend!
Cooling Down
As expected… temperatures have cooled into the 50s over the northern half of the state with a chilly northwest wind…
The severe weather threat for South Alabama is winding down as the stable air moves in from the north…
The sky will clear over the next 6 hours, and we will be down in the low to mid 30s by daybreak tomorrow. The weekend will be cool and dry….
Tornado Warning : BMX@ 2/24/2012 11:00:31 AM
Here is a new weather bulletin from AlabamaWX.com. Stand by for more details.
WFUS54 KBMX 241701
TORBMX
ALC005-011-241730-
/O.NEW.KBMX.TO.W.0019.120224T1701Z-120224T1730Z/
BULLETIN – EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1101 AM CST FRI FEB 24 2012
THE NATIONAL WEATHER SERVICE IN BIRMINGHAM HAS ISSUED A
* TORNADO WARNING FOR…
NORTHWESTERN BARBOUR COUNTY IN SOUTHEAST ALABAMA…
BULLOCK COUNTY IN SOUTHEAST ALABAMA…
* UNTIL 1130 AM CST
* AT 1058 AM CST…THE NATIONAL WEATHER SERVICE INDICATED A SEVERE
THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM
WAS LOCATED NEAR LINWOOD…OR 10 MILES NORTHEAST OF TROY…AND
MOVING EAST AT 55 MPH.
* LOCATIONS IMPACTED INCLUDE…
UNION SPRINGS…MIDWAY…INVERNESS…BOOT HILL…ABERFOIL…
PICKETT…CLAYTON…BARBOUR COUNTY PUBLIC LAKE DAM…SIMSVILLE AND
TANYARD.
PRECAUTIONARY/PREPAREDNESS ACTIONS…
TAKE COVER NOW. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE
LOWEST FLOOR OF A STURDY BUILDING.
&&
TO REPORT SEVERE WEATHER…
CALL 1-800-856-0758.
LAT…LON 3186 8567 3188 8566 3188 8579 3197 8579
3197 8588 3199 8590 3205 8590 3206 8595
3214 8595 3222 8543 3214 8542 3187 8542
TIME…MOT…LOC 1701Z 250DEG 50KT 3194 8581
$$
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Tornado Warning : BMX@ 2/24/2012 10:33:59 AM
Here is a new weather bulletin from AlabamaWX.com. Stand by for more details.
WFUS54 KBMX 241634
TORBMX
ALC109-241715-
/O.NEW.KBMX.TO.W.0018.120224T1634Z-120224T1715Z/
BULLETIN – EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1034 AM CST FRI FEB 24 2012
THE NATIONAL WEATHER SERVICE IN BIRMINGHAM HAS ISSUED A
* TORNADO WARNING FOR…
NORTHERN PIKE COUNTY IN SOUTHEAST ALABAMA…
* UNTIL 1115 AM CST
* AT 1029 AM CST…THE NATIONAL WEATHER SERVICE INDICATED A SEVERE
THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM
WAS LOCATED NEAR BRADLEYTON…OR 10 MILES NORTH OF LUVERNE…AND
MOVING EAST AT 55 MPH.
* LOCATIONS IMPACTED INCLUDE…
TROY…ANSLEY…TROY MUNICIPAL AIRPORT…TROY UNIVERSITY…
ANTIOCH…LINWOOD…BANKS…ORION…MOSSY GROVE AND SANDFIELD.
PRECAUTIONARY/PREPAREDNESS ACTIONS…
TAKE COVER NOW. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE
LOWEST FLOOR OF A STURDY BUILDING.
&&
TO REPORT SEVERE WEATHER…
CALL 1-800-856-0758.
LAT…LON 3173 8615 3178 8615 3179 8621 3188 8618
3196 8619 3196 8600 3202 8599 3202 8590
3197 8588 3197 8579 3188 8579 3188 8574
3174 8572
TIME…MOT…LOC 1634Z 262DEG 48KT 3187 8622
$$
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