Jump to content
  • Member Statistics

    17,606
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

Severe Weather Thread (April 2, 2012 - April 4, 2012)


David Reimer

Recommended Posts

  • Replies 335
  • Created
  • Last Reply

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE NEW ORLEANS LA

1154 PM CDT TUE APR 3 2012

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A

* TORNADO WARNING FOR...

WEST CENTRAL ORLEANS PARISH IN SOUTHEAST LOUISIANA...

THIS INCLUDES THE CITY OF NEW ORLEANS...

* UNTIL 1230 AM CDT

* AT 1153 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO OVER NEW

ORLEANS. THIS TORNADO WAS NEARLY STATIONARY.

Link to comment
Share on other sites

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE NEW ORLEANS LA

1154 PM CDT TUE APR 3 2012

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A

* TORNADO WARNING FOR...

WEST CENTRAL ORLEANS PARISH IN SOUTHEAST LOUISIANA...

THIS INCLUDES THE CITY OF NEW ORLEANS...

* UNTIL 1230 AM CDT

* AT 1153 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO OVER NEW

ORLEANS. THIS TORNADO WAS NEARLY STATIONARY.

post-277-0-37349000-1333515709.png

Link to comment
Share on other sites

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE NEW ORLEANS LA

1230 AM CDT WED APR 04 2012

.TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON

.DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.

..REMARKS..

1158 PM TSTM WND DMG 3 NE NEW ORLEANS 30.00N 90.05W

04/03/2012 ORLEANS LA BROADCAST MEDIA

ROOF BLOWN OFF OF HOUSE AT GENTILLY AND FRANKLIN AVENUES.

SEVERAL HOMES DAMAGED. POSSIBLE TORNADO.

Link to comment
Share on other sites

I did notice that GTG shear even on the hi-res, low-scanning TDWRs (which cleanly sampled both of the supercells in question) never appeared outrageously strong, even as video showed tractor trailers flying through the sky. A lot of chaser and local video from the ground seems to suggest visually* that the upward velocities were more impressive than the tangential ones. This is a very intriguing case that I'm sure will be explored further in the future.

*can't be taken as a truly reliable indicator of the real flow, of course

Link to comment
Share on other sites

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX

102 PM CDT WED APR 4 2012

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* TORNADO WARNING FOR...

GALVESTON COUNTY IN SOUTHEASTERN TEXAS...

EXTREME NORTHEASTERN BRAZORIA COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 145 PM CDT

* AT 1259 PM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM

CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED

NEAR ALVIN...AND MOVING SOUTHEAST AT 10 MPH. LARGE HAIL IS ALSO

EXPECTED.

* LOCATIONS IMPACTED INCLUDE...

ALVIN...SANTA FE AND HILLCREST.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO A BASEMENT OR AN INTERIOR ROOM ON THE

LOWEST FLOOR OF A STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE

HOME OR OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND

PROTECT YOURSELF FROM FLYING DEBRIS.

post-6398-0-71533300-1333563449.png

Link to comment
Share on other sites

From Jeff:

Extremely dangerous thunderstorm producing frequent reports of baseball and golfball size hail moving toward the western end of Galveston Island. As this storm passed over Alvin there have been numerous reports of baseball size hail breaking windows of vehicles and houses in and around Alvin Community College.

This storm is nearing the northern side of west Bay and will be crossing into west Bay and western Galveston Island within the next 20 minutes. Although the radar is showing a weakening trend, this remains a dangerous storm.

Link to comment
Share on other sites

From NESDIS:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 04/04/12 1901Z

SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-763-8678

LATEST DATA USED: GOES-13 1845Z KUSSELSON

NOAA AMSU:1614Z DMSP SSMIS:1223Z

.

LOCATION...SE TEXAS...

.

ATTN WFOS...HGX...

ATTN RFCS...WGRFC...

.

EVENT...MICROWAVE PASS SHOWING DEEP PRECIPITABLE WATER WITH OFFSHORE

CONVECTIVE COMPLEX FOLLOWING ALONG OUTFLOW INTO SE TEXAS CONVECTION...

.

SATELLITE ANALYSIS AND TRENDS...NICE 1614Z NOAA AMSU PASS OVER THE WESTERN

GULF OF MEXICO SHOWING OUTFLOW HIGHER PRECIP WATER MOISTURE TRAILING

ALONG THE OUTFLOW AND BACK INTO THE SE TEXAS COAST. THIS WAS ALLOWING

SMALLER COMPLEX BRAZORIA INTO GALVESTON COUNTY TO HANG TOGETHER WITH

SOME EMBEDDED TRAINING CELLS. EAST EXTENT OF COMPLEX DRIFTING EAST AND

SE TOWARD GULF COAST...BUT BACK EDGE MOVING SLOWLY AND CONVECTIVE CELLS

TRYING TO FORM TO SOUTHWEST FOR POTENTIAL TRAINING SCENARIO...AT LEAST

BRAZORIA TO NEAR WEST/SW GALVESTON COUNTY. WITH GPS PW VALUES NEAR 1.6"

AND A FEW GOES SOUNDER VALUES EVEN HIGHER...CERTAINLY COULD GET AMOUNTS

OF 1-1.5" PER HR WITH ISOLATED RATES TO 2.0"/HR, ESPECIALLY IF THERE

ARE ANY OVERSHOOTING CLOUD TOPS LIKE 1745Z AND 1830Z.

.

AN ANNOTATED SATELLITE GRAPHIC SHOWING THE HEAVY PRECIPITATION THREAT AREA

SHOULD BE AVAILABLE ON THE INTERNET ADDRESS LISTED BELOW IN APPROXIMATELY

10-15 MINUTES.

.

SHORT TERM OUTLOOK VALID 1900-2200Z...MEDIUM CONFIDENCE FACTOR IN SHORT

TERM OUTLOOK...CONVECTIVE DEVELOP TO SW OF THIS SMALL COMPEX THE KEY...IF

CELLS CONTINUE TO DEVELOP...THEN THERE IS A CHANCE THEY COULD FEED

INTO BACK PART OF COMPEX AND CONTINUE TO GIVE BURSTS OF HVY RAIN AND

INCREASE FF. BUT NO WHERE NEAR A CERTAINTY...JUST WILL HAVE TO WATCH

THE CELL DEVELOPMENT AND POTENTIAL TRAINING IN MATAGORDA/WHARTON AND

EAST THAT COULD GIVE ADDITIONAL HVY RAIN TO BRAZORIA AND GALVESTON COUNTY.

post-32-0-14278500-1333567019.gif

Link to comment
Share on other sites

I did notice that GTG shear even on the hi-res, low-scanning TDWRs (which cleanly sampled both of the supercells in question) never appeared outrageously strong, even as video showed tractor trailers flying through the sky. A lot of chaser and local video from the ground seems to suggest visually* that the upward velocities were more impressive than the tangential ones. This is a very intriguing case that I'm sure will be explored further in the future.

*can't be taken as a truly reliable indicator of the real flow, of course

I did notice that too. I have a hypothesis that CAPE correlates stronger with upward velocities in a tornado, but that shear/helicity correlates stronger with the tangential velocities. Yesterday was a high CAPE/low shear day, with the former around 2000-3000 J/kg, but the latter only around 100 m2/s2.

Link to comment
Share on other sites

Hah that one little cluster of supercells is causing more issues than it's worth! Furthermore as they appear to be training over pretty much the same area I'd wager there is gonna be some flooding issues there as well. Not to mention more nasty hail, yikes.

Also

I have a hypothesis that CAPE correlates stronger with upward velocities in a tornado, but that shear/helicity correlates stronger with the tangential velocities. Yesterday was a high CAPE/low shear day, with the former around 2000-3000 J/kg, but the latter only around 100 m2/s2.

Even with me being someone completely untrained in meteorology, that's incredibly fascinating. The main reason I come here is to hear people that know what they're doing put forth interesting hypothesis and explanations for severe weather events. Am I or am I not the only one that thought the videos from Dallas yesterday were like a less intense version of the Pampa tornado videos?

Link to comment
Share on other sites

That's one of the most amazing close-range videos I have ever seen. Reminds me a little of the Rice, TX video from 2010 when it crosses the highway, but even clearer. The vortex action is incredible and I wouldn't dare be as close as the folks in the cars appear to be, haha. Debris is falling absolutely everywhere.

Link to comment
Share on other sites

Reading reports all over that the tornado damage near Forney looked EF3+, but have to admit I'm somewhat at a loss when looking at the FWS data...

The hook echo is impressive enough but the velocity signature looks really marginal for that strong of a tornado. Certainly much weaker than Arlington at the same height AGL.

Link to comment
Share on other sites

Which of the EF-2 tornadoes was the one tossing the tractor trailer's around? I know it wasnt the EF3 forney tornado... I'm pretty amazed that an EF-2 could lift 10,000 lb+ objects like that and toss them around.

Lancaster tornado as it hit a shipping/trucking facility on Interstate 20 just east of Interstate 35E.

Link to comment
Share on other sites

Reading reports all over that the tornado damage near Forney looked EF3+, but have to admit I'm somewhat at a loss when looking at the FWS data...

The hook echo is impressive enough but the velocity signature looks really marginal for that strong of a tornado. Certainly much weaker than Arlington at the same height AGL.

Tim Marshall actually surveyed that tornado and provided the EF-3 rating. He has several damage survey photos and thoughts on his facebook.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...