Severe weather threat 5-9-06

[SamSagnella]

From another board:
"Collin County spotter reports home hit just now by tornado near Westminster on FM 2862. Occupants appear to be accounted for.

"Debris is everywhere." another spotter just says.

147.18MHZ is getting out there tonight... I'm 100 miles away and it's S9. If you're in the vicinity, you might tune it in."

EDIT: Storm hit about 1045CT.

Spotter reports funnel lifted at 1055CT, lowering remains."

[SamSagnella]

OK, but how can you know how strong tornadic developments are ?

for that you need a special kind of radar program such as grlevel3
http://www.grlevelx.com

[Bunkertor]

All right ! I´ll check this. But i can´t use it from germany ?

[CrazyC83]

All right ! I´ll check this. But i can´t use it from germany ?

Yes you can, although they are useless for local tracking...

[Bunkertor]

[TexasStooge]

From another board:
"Collin County spotter reports home hit just now by tornado near Westminster on FM 2862. Occupants appear to be accounted for.

"Debris is everywhere." another spotter just says.

147.18MHZ is getting out there tonight... I'm 100 miles away and it's S9. If you're in the vicinity, you might tune it in."

EDIT: Storm hit about 1045CT.

Spotter reports funnel lifted at 1055CT, lowering remains."

I just got an update on that, 3 people were killed, about a dozen injured, and homes just ripped off the foundtion. You'll see more of that info in the severe weather aftermath topic.

[Extremeweatherguy]

DAY 4-8 CONVECTIVE OUTLOOK RESENT 1
NWS STORM PREDICTION CENTER NORMAN OK
0440 AM CDT WED MAY 10 2006

VALID 131200Z - 181200Z

...DISCUSSION...
MEDIUM RANGE MODELS AGREE THAT THE LARGE UPPER CYCLONE OVER THE ERN
THIRD OF THE NATION WILL BE MAINTAINED AT LEAST THROUGH THE UPCOMING
WEEKEND. STRONG IMPULSE THAT WILL CROSS THE ROCKIES ON FRI WILL
CONTINUE TO DIG SEWD TOWARD THE CNTRL GULF COASTAL AREA ON SAT.
ASSOCD COLD FRONT WILL SWEEP SWD...REACHING THE GULF COAST AND THE
SRN HIGH PLAINS BY EARLY SUNDAY. LOW-LEVEL MOISTURE RETURN BENEATH
STEEP LAPSE RATES SHOULD PROVIDE AT LEAST MODEST INSTABILITY ALONG
THE FRONT FOR TSTMS. NWLY H5 FLOW ATOP SWLY LOW-LEVEL FLOW WILL
LIKELY CONTRIBUTE TO SUFFICIENT SHEAR FOR ORGANIZED STORMS FROM
PARTS OF TX EWD TO ALONG THE GULF COAST.

ELSEWHERE...FAVORED NWLY FLOW ALOFT AND RETURN OF MOISTENING UPSLOPE
FLOW WILL CONTRIBUTE TO INCREASING CHANCES FOR CNTRL/SRN HIGH PLAINS
MCS EPISODES...PRIMARILY LATE IN THE WEEKEND AND EARLY NEXT WEEK.
TIMING AND LOCATION UNCERTAINTIES PRECLUDE AN ENHANCED SEVERE OTLK
ATTM.

..RACY.. 05/10/2006

Looks like another severe event setting up this weekend.

[Dr. Jonah Rainwater]

Last night around 10:30 I saw that storm rolling in. It wasn't like most storms...the sky was clear until this sudden wall of cloud that was visibly vertical even at night...lightning crackling through the whole thing. It looked like it was coming this way so i went and checked the NWS radar...that was a hook echo if I ever saw one. The tornado warning was issued a few minutes later for my county, but the supercell passed to the north of the suburbs. (thankfully - can you imagine the damage if that tornado had passed through southern Collin County instead?)

By the looks of the damage, that's at least an F2, probably an F3. Some of those levelled buildings look like sturdy wood-frame houses.

[6SpeedTA95]

Yeah damage was pretty significant although I only saw one damaged structure on the news this morning.

[CrazyC83]

It looked like a high F2 or F3 in my view. They weren't totally flattened (from my view) so it should be no more than F3. Still a major tornado - it reminds people that even isolated events can produce a strong killer...

Anna and Childress both sound like F2's from my view.

[CrazyC83]

Excellent 30-minute aerial view here: http://www.dallasnews.com/sharedcontent ... &catId=342 - looks like low-end F3 to me

[Dr. Jonah Rainwater]

Westminster doesn't have tornado sirens. The town actually went bankrupt last year and unincorporated itself. This tornado seems to be another nail in the coffin for poor Westminster, Texas.

[CrazyC83]

Hopefully it will rebuild and get back on its feet...

[SouthFloridawx]

Wow that's some pretty bad damage thanks for the video link.

[PTrackerLA]

Very interesting discussion out of NWS New Orleans this morning about the volatile situation that exists in our area. Big issue is the cap, if it continues to hold we might not see anything. If it breaks, according to them, watch out.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1030 AM CDT WED MAY 10 2006

.UPDATED DISCUSSION...
TODAY`S FORECAST IS HIGHLY CONDITIONAL AND CONFIDENCE IS RIDING ON
INTEGRITY OF CAPPED AIRMASS. 12Z SOUNDING IS VERY UNSTABLE ABOVE 600
MB LEVEL WITH ABOUT A 300 MB LAYERED CAP TO OVERCOME...ABOUT 2C. THE
ONGOING FORECAST LOOKS ON TRACK...EVEN THE LOW POPS...BUT ONE SHOULD
NOT TAKE LIGHTLY THE POTENTIAL SEVERE WEATHER AND HEAVY RAINFALL
THREAT IF THE CAP ERODES. WE WILL BE LAUNCHING AN 18Z SOUNDING TO
ASSESS THE CAP STRENGTH AND CONVECTIVE INTEGRITY. MEANWHILE...VERY
STRONG DIFLUENCE PATTERN ALOFT AND JET DYNAMICS TO AUGMENT THE OMEGA
OVER THE AREA ALONG WITH 150% OR GREATER PRECIPITABLE WATER VALUES
WILL PRODUCE AN EFFICIENT RAINFALL CAPABILITY. WILL NOT ISSUE A
FLOOD WATCH DUE TO CONDITIONAL NATURE OF THE FORECAST BUT LOCALIZED
FLOOD STATEMENTS AND WARNINGS MAY BE WARRANTED ONCE RAINFAL BREAKS
OUT.

RAN THE PRECIPITATION CALCULATOR/RICKS INDEX USING A 343K LIFT FROM
900 MB THROUGH THE CAP YIELDS PROBABILITY OF PRECIPITATION
79%...PRECIPITATION 2.82" WITH A POTENTIAL FOR 7.32 INCHES FOR TEMPS
BELOW 75F!. RICKS INDEX 179...PROB OF SEVERE 69%. FORECAST WIND
GUSTS 73 KTS/84 MPH...FORECAST HAIL SIZE 2.25" DIAMETER (HEN EGG).
TORNADO THREAT UP TO F3 POSSIBLE, HELICITY DEPENDENT. SOUNDING VIL
47=HEN EGG...40=PENNY. ARKANSAS METHOD VIL OF THE DAY 56.

BOTTOM LINE...EVERYTHING POINTS TO SEVERE WEATHER AND SUBSTANTIATED
MODERATE RISK BUT THE CAPPED AIRMASS IS LOWERING CONFIDENCE IN
WIDESPREAD OCCURRENCE IN OUR WARNING AREA. WILL BE UPDATING HWO
SHORTLY TO DETAIL THE ABOVE INFORMATION AND WILL BE CLOSELY
MONITORING TRENDS THROUGHOUT THE AFTERNOON.

[Extremeweatherguy]

MESOSCALE DISCUSSION 0831
NWS STORM PREDICTION CENTER NORMAN OK
0234 PM CDT WED MAY 10 2006

AREAS AFFECTED...SRN/SERN TX

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 101934Z - 102130Z

SVR TSTMS ARE ANTICIPATED TO BEGIN DEVELOPING ALONG A COLD FRONT
FROM SERN TX INTO THE MIDDLE TX COASTAL PLAIN IN THE NEXT 1-2 HRS.
SVR TSTMS MAY DEVELOP AS FAR SOUTH AS THE LOWER RIO GRANDE RIVER
VALLEY OF SOUTH TX. AREA WILL BE MONITORED FOR THE POTENTIAL OF ONE
OR MORE WW/S BY 21Z.

LATEST VIS IMAGERY SHOWS TOWERING CU DEVELOPING ALONG A COLD FRONT
FROM JUST NORTH OF HOUSTON SWWD ALONG THE MIDDLE TX COASTAL PLAIN.
MODIFIED RUC SOUNDINGS SHOW AN EXTREMELY UNSTABLE AIRMASS WITH
MLCAPES ABOVE 5000 J/KG AND VERY LITTLE CINH REMAINING. CONVERGENCE
ALONG THE FRONT /WHICH IS 2 KM DEEP PER RECENT GRK VWP DATA/ SHOULD
SUPPORT TSTM DEVELOPMENT WITHIN THE NEXT 1-2 HRS. THE COMBINATION OF
MODERATE MID LEVEL FLOW /30 KTS/ AND INSTABILITY SHOULD SUPPORT
RAPID STORM INTENSIFICATION AND A LARGE HAIL/DMGG WIND THREAT. A WW
MAY BE NEEDED FOR THIS AREA SHORTLY.

FURTHER SOUTH ALONG THE LOWER TX COAST/LOWER RIO GRANDE RIVER
VALLEY...A VERY UNSTABLE AIRMASS EXISTS AS WELL. A SLIGHTLY STRONGER
CAP THAN FURTHER NORTH /PER THE 12Z CRP SOUNDING/ MAY DELAY
CONVECTIVE INITIATION FOR ANOTHER FEW MORE HRS...UNTIL THE FRONTAL
BOUNDARY MOVES INTO THE AREA BEGINNING AROUND 21Z. AGAIN THE DEGREE
OF INSTABILITY AND MODEST SHEAR WOULD SUPPORT A SVR HAIL/WIND THREAT
QUICKLY AFTER ANY STORM INITIATION. SLIGHTLY GREATER LOW LVL LAPSE
RATES SUGGEST THAT THE WIND THREAT MAY BE SLIGHTLY HIGHER THAN IN
THE MIDDLE TX COAST.

..CROSBIE.. 05/10/2006


ATTN...WFO...HGX...CRP...EWX...BRO...

31169486 29999676 28899810 27119913 26669912 26339880
26009808 26179791 26959748 28299676 29379478

[SamSagnella]

Code: Select all

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
350 PM CDT WED MAY 10 2006

...INITIAL RESULTS FROM DAMAGE SURVEY IN COLLIN AND GRAYSON COUNTIES
FROM STORMS ON MAY 9TH 2006...

NATIONAL WEATHER SERVICE METEOROLOGISTS CONTINUE TO SURVEY DAMAGE
FROM TUESDAY EVENING'S TORNADOES ACROSS COLLIN AND GRAYSON COUNTIES.
THE SURVEY TEAM FOUND DAMAGE FROM APPROXIMATELY 2 MILES
EAST-NORTHEAST OF ANNA IN COLLIN COUNTY TO 2 MILES SOUTH OF
WHITEWRIGHT IN SOUTHEAST GRAYSON COUNTY.  A SMALL BREAK IN THE
DAMAGE PATH EAST OF ANNA WAS RECENTLY FOUND...SUPPORTING SPOTTER
REPORTS OF TWO SEPARATE TORNADOES. THE WORST DAMAGE TO SINGLE FAMILY
HOMES...JUST NORTH OF WESTMINSTER NEAR AND EAST OF FM 3133...HAS
BEEN RATED UPPER F3 ON THE SCALE.

NATIONAL WEATHER SERVICE METEOROLOGISTS CONTINUE TO SURVEY THE
DAMAGE AND ARE WORKING WITH WIND ENGINEERING EXPERTS TO PRODUCE A
MORE DETAILED DAMAGE ANALYSIS AND SUMMARY. 

AN UPDATED PUBLIC INFORMATION STATEMENT WILL BE ISSUED LATER TODAY.

I'm not surprised that this received as high of a rating as it did, mainly because of the aerial video circulating online showing tremendous scouring of the topsoil near Westminster. It takes a strong tornado to suck all the grass out of the ground. There was at least one house that was reduced to its foundation and though it wasn't a 'clean sweep', the debris was removed at least a short ways downstream (I'd have to assume that was the upper-end F3 house that KFWD mentioned as that's pretty standard damage for a borderline F3/F4 tornado).

http://www.wfaa.com/ click - "Watch video of the tornado's path"

[CrazyC83]

From my view, those houses that were wiped clean were weak mobile homes. Based on what I saw, I think they over-rated the tornado; IMO it was a low-end F3 (and barely one at that).

[SamSagnella]

Whatever videos we have access to show just a small piece of the evidence they look at when assigning a rating. Not only do I trust the NWS' damage assesment teams (most of the time at least), I also agree with their rating. Based on that video linked above there's no way this tornado was weaker than a solid F3. I actually wouldn't be surprised if the final rating puts this one at an F4 - this was one intense tornado; the ground scouring seen here is something that an F2 or even a weak F3 is incapable of.

Pictures of the Westminster tornado taken by Mike Mezeul II.