Severe Weather Discussion: 2/17/08

ndg
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Posts: 9,974

Severe Weather Discussion: 2/17/08 Feb 16, 2008 16:50:31 GMT -6

Quote

Post by ndg on Feb 16, 2008 16:50:31 GMT -6

From KLIX's latest AFD write up:

SEVERE WEATHER POTENTIAL...
RAN RICKS INDEX AND REVIEWED CHAP OUTPUT FOR BOTH THE NAM AND GFS
MODEL SOUNDINGS FOR SEVERAL LOCATIONS IN THE CWA. THERE ARE
INDICATIONS FOR SEVERE THUNDERSTORMS FOR AT LEAST ONE MODEL TIME
STEP OVERNIGHT OR VERY EARLY SUNDAY. THE GFS IS MORE SEVERE THAN
THE NAM AND APPEARS TO BE SLOWER THAN THE NAM SOLUTION. BELOW IS A
TABLE OF OUTPUTS FROM THE CHAP INDICATING THE WORST TIME STEP
OUTPUT FOR EACH LOCATION TESTED.

LOCATION MODEL TIMESTEP PROB SVR HAILSIZE GUSTS TORNADO QPF
KMCB 12Z NAM 17/12Z 29% PENNY 57KT EF1 0.86"
KMCB 12Z GFS 17/12Z 69% PING PONG 87KT EF3 0.63"

KBTR 12Z NAM 17/12Z 0% PEA 38KT NIL 0.86"
KBTR 12Z GFS 17/15Z 7% MARBLE 48KT NIL 1.05"

KASD 12Z NAM 17/12Z 0% GRAUPEL 37KT WATERSPOUTS 0.71"
KASD 12Z GFS 17/18Z 9% MARBLE 51KT WATERSPOUTS 0.71"

KMSY 12Z NAM 17/12Z 6% PEA-MARBLE 49KT WATERSPOUTS 0.65"
KMSY 12Z GFS 17/18Z 21% MARBLE 58KT EF0 0.45"

KGPT 12Z NAM 17/15Z 0% PEA 44KT WATERSPOUTS 0.59"
KGPT 12Z GFS 17/18Z 16% MARBLE 57KT WATERSPOUTS 1.22"

WE LAUNCHED AN 18Z SPECIAL RELEASE BALLOON TO ASSIST WITH SEVERE
WEATHER PRE-STORM ENVIRONMENT MONITORING. SOUNDING SHOWS A
CONSIDERABLE AMOUNT OF LOW LEVEL STABILITY TO ERODE. THIS SHOULD
BE THE CASE MAINLY AFTER MIDNIGHT AS BEST DYNAMICS APPROACHES
BEFORE LIFTING NORTHWARD AND LARGE SCALE LIFT TAKES OVER. THE THREAT
SHOULD DIMINISH AS CONVECTION PUSHES EAST OF THE PEARL RIVER. AT THIS
TIME AND BASED ON ABOVE OUTPUT...GREATEST RISK WILL BE NEAR
ATCHAFALAYA BASIN INTO SOUTHWEST MISSISSIPPI AND GRADUALLY
TAPERING IN INTENSITY INTO NEW ORLEANS METRO AREA AND MISSISSIPPI
GULF COAST EARLY SUNDAY.

&&

tracker1
Tropical Low

Posts: 28

Severe Weather Discussion: 2/17/08 Feb 16, 2008 17:08:23 GMT -6

Quote

Post by tracker1 on Feb 16, 2008 17:08:23 GMT -6

ndg said:

From KLIX's latest AFD write up:

SEVERE WEATHER POTENTIAL...
RAN RICKS INDEX AND REVIEWED CHAP OUTPUT FOR BOTH THE NAM AND GFS
MODEL SOUNDINGS FOR SEVERAL LOCATIONS IN THE CWA. THERE ARE
INDICATIONS FOR SEVERE THUNDERSTORMS FOR AT LEAST ONE MODEL TIME
STEP OVERNIGHT OR VERY EARLY SUNDAY. THE GFS IS MORE SEVERE THAN
THE NAM AND APPEARS TO BE SLOWER THAN THE NAM SOLUTION. BELOW IS A
TABLE OF OUTPUTS FROM THE CHAP INDICATING THE WORST TIME STEP
OUTPUT FOR EACH LOCATION TESTED.

LOCATION MODEL TIMESTEP PROB SVR HAILSIZE GUSTS TORNADO QPF
KMCB 12Z NAM 17/12Z 29% PENNY 57KT EF1 0.86"
KMCB 12Z GFS 17/12Z 69% PING PONG 87KT EF3 0.63"

KBTR 12Z NAM 17/12Z 0% PEA 38KT NIL 0.86"
KBTR 12Z GFS 17/15Z 7% MARBLE 48KT NIL 1.05"

KASD 12Z NAM 17/12Z 0% GRAUPEL 37KT WATERSPOUTS 0.71"
KASD 12Z GFS 17/18Z 9% MARBLE 51KT WATERSPOUTS 0.71"

KMSY 12Z NAM 17/12Z 6% PEA-MARBLE 49KT WATERSPOUTS 0.65"
KMSY 12Z GFS 17/18Z 21% MARBLE 58KT EF0 0.45"

KGPT 12Z NAM 17/15Z 0% PEA 44KT WATERSPOUTS 0.59"
KGPT 12Z GFS 17/18Z 16% MARBLE 57KT WATERSPOUTS 1.22"

WE LAUNCHED AN 18Z SPECIAL RELEASE BALLOON TO ASSIST WITH SEVERE
WEATHER PRE-STORM ENVIRONMENT MONITORING. SOUNDING SHOWS A
CONSIDERABLE AMOUNT OF LOW LEVEL STABILITY TO ERODE. THIS SHOULD
BE THE CASE MAINLY AFTER MIDNIGHT AS BEST DYNAMICS APPROACHES
BEFORE LIFTING NORTHWARD AND LARGE SCALE LIFT TAKES OVER. THE THREAT
SHOULD DIMINISH AS CONVECTION PUSHES EAST OF THE PEARL RIVER. AT THIS
TIME AND BASED ON ABOVE OUTPUT...GREATEST RISK WILL BE NEAR
ATCHAFALAYA BASIN INTO SOUTHWEST MISSISSIPPI AND GRADUALLY
TAPERING IN INTENSITY INTO NEW ORLEANS METRO AREA AND MISSISSIPPI
GULF COAST EARLY SUNDAY.

&&

Hmmmmm. Leaving it up to the wx navigator.

;D

tracker1 Tropical Low Posts: 28	Severe Weather Discussion: 2/17/08 Feb 16, 2008 17:27:57 GMT -6 Quote Select Post Deselect Post Link to Post Back to Top Post by tracker1 on Feb 16, 2008 17:27:57 GMT -6 Severe thunderstorm /tornado watches issued for Cent. & East TX.
	Last Edit: Feb 16, 2008 17:31:41 GMT -6 by tracker1

Zack Fradella
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Severe Weather Discussion: 2/17/08 Feb 16, 2008 17:51:52 GMT -6

Quote

Post by Zack Fradella on Feb 16, 2008 17:51:52 GMT -6

Th setup for this event is very dangerous. However, we could see anything from absolutely nothing to a severe weather outbreak worst than Tuesday. The kinematics are very favorable for severe winds and intense tornadoes, but the thermodynamics are all in question. You cannot get those tornadoes or severe winds without the thermodyanmics so what happens?

I guess we will see but please remember that slight risk we are under can be way off.

Zack Fradella
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StormCast - Gulf Coast Weather Founder

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tracker1
Tropical Low

Posts: 28

Severe Weather Discussion: 2/17/08 Feb 16, 2008 18:03:24 GMT -6

Quote

Post by tracker1 on Feb 16, 2008 18:03:24 GMT -6

admin said:

Th setup for this event is very dangerous. However, we could see anything from absolutely nothing to a severe weather outbreak worst than Tuesday. The kinematics are very favorable for severe winds and intense tornadoes, but the thermodynamics are all in question. You cannot get those tornadoes or severe winds without the thermodyanmics so what happens?

I guess we will see but please remember that slight risk we are under can be way off.

To chase, or not to chase, that is the prevailing question!LOL!

Yea/nay?

Last Edit: Feb 16, 2008 18:05:36 GMT -6 by tracker1

futuremet
Meteorologist

Posts: 1,430

Severe Weather Discussion: 2/17/08 Feb 16, 2008 19:18:09 GMT -6

Quote

Post by futuremet on Feb 16, 2008 19:18:09 GMT -6

Okay, just got in. Tomorrow is continuing to look like a mdt risk day for portions of MS,AL,GA,FL (maybe even Northshore imo). The farther north the instability reaches, the greater the outbreak this will turn out to be. An isolated significant tornado or 2 could occur in the area where the northern edge of highest CAPEs and the southern end of best helicities overlap. Central MS, Central AL, Central GA and points southward look prime for severe weather tomorrow. The risk would be higher in SELA and may still be but the storms are expected to roll through early morning which isn't the best time for full svr potential. One other thing that concerns me, though, is that tornado around baton rouge occurred at a temp of around 60 with DT's in the low 50s. I'll take a look at more things around the 00z model outputs.
Zack, what's the latest for the chase? Where are we targeting and when are we meeting?

U of U Atmospheric Science - Focus in Rapid Intensification of Tropical Cyclones

tracker1 Tropical Low Posts: 28	Severe Weather Discussion: 2/17/08 Feb 16, 2008 19:50:48 GMT -6 Quote Select Post Deselect Post Link to Post Back to Top Post by tracker1 on Feb 16, 2008 19:50:48 GMT -6 Well fellow chasers, I hope we know by 10 pm if not sooner if we are indeed going, or not. If I knew now, I'd go to sleep now to get a good rest. We may wind up in Ms.!

tracker1 Tropical Low Posts: 28	Severe Weather Discussion: 2/17/08 Feb 16, 2008 20:31:24 GMT -6 Quote Select Post Deselect Post Link to Post Back to Top Post by tracker1 on Feb 16, 2008 20:31:24 GMT -6 Weather is beginning to change here. A few gusts of wind, along w/ BP dropping.

strato474
Category 2

Posts: 538

Severe Weather Discussion: 2/17/08 Feb 16, 2008 20:36:29 GMT -6

Quote

Post by strato474 on Feb 16, 2008 20:36:29 GMT -6

The SPC hints at some QLCS....those can be tricky to warn for as far as tornadoes go...

MESOSCALE DISCUSSION 0246
NWS STORM PREDICTION CENTER NORMAN OK
0718 PM CST SAT FEB 16 2008

AREAS AFFECTED...PORTIONS SE TX...WRN LA.

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 170118Z - 170245Z

SOMETIME BEFORE WW 58 EXPIRES AT 03Z...ANOTHER WW PROBABLY WILL BE
REQUIRED THAT WOULD INCLUDE THIS AREA...EITHER AS REPLACEMENT FOR WW
58 OR TACKED ONTO ITS ERN FRINGE.

BOUNDARY LAYER AIR MASS ACROSS EXTREME SE TX AND SWRN LA IS
RELATIVELY STABLE ATTM BUT SHOULD DESTABILIZE FAVORABLY FOR SVR
THREAT TO INCREASE DURING NEXT FEW HOURS. RELATIVELY BACKED FLOW
ACROSS THIS REGION HAS MAINTAINED VERY STRONG DEEP-LAYER SHEAR...BUT
ALSO HAS KEPT PARTIALLY MODIFIED AIR MASS WITH LITTLE OR NO 0-3 KM
AGL CAPE ACROSS THIS REGION. THIS AIR MASS EXISTS N OF DIFFUSE
MARINE/WARM FRONT THAT IS ANALYZED ATTM FROM NEAR LFK SSEWD ACROSS
ERN GLS BAY AREA...THEN ESEWD OVER GULF. PRIND BOUNDARY WILL
CONTINUE TO WEAKEN AND LIFT NEWD...WITH SFC FLOW VEERING TO MORE SLY
COMPONENT...INCREASING THETAE ADVECTION INTO THIS REGION. THIS
PROCESS SHOULD REDUCE STG MLCINH IMPARTED BY STABLE LAYER AROUND 750
MB THAT WAS EVIDENT IN 00Z LCH SOUNDING. TRIANGULAR AREA NEAR COAST
WILL HAVE GREATEST POTENTIAL FOR EFFECTIVE LIFTED PARCELS TO BE
ROOTED NEAR SFC...AMIDST VERTICAL SHEAR ENVIRONMENT THAT WILL REMAIN
VERY FAVORABLE. 0-1 KM SRH ABOVE 500 J/KG AND 50-70 KT EFFECTIVE
SHEAR MAGNITUDES WILL MAINTAIN TORNADO POTENTIAL WITH RELATIVELY
DISCRETE CONVECTION...AS WELL AS SUPPORTING POTENTIAL FOR DAMAGING
GUSTS AND BRIEF TORNADOES WITH BOWS AND QLCS CIRCULATIONS IN MAIN
CONVECTIVE PLUME.

ALTHOUGH AREA OF GREATEST SFC-BASED SVR POTENTIAL WILL SHRINK
COASTWARD ACROSS LA WITH TIME...THREAT FOR ISOLATED STG/DAMAGING
GUSTS AND LARGE HAIL MAY PERSIST WITH NRN PORTION OF LINE OVER
WRN/NRN LA.

University of North Carolina Asheville

undergraduate student in meteorology
minor in environmental science

futuremet
Meteorologist

Posts: 1,430

Severe Weather Discussion: 2/17/08 Feb 16, 2008 20:44:10 GMT -6

Quote

Post by futuremet on Feb 16, 2008 20:44:10 GMT -6

NAM 00Z has continued to increase instability across Central MS, AL, and SW GA. 1000+ Capes extending up to and just north of a W to E line through Birmingham. If the NAM is right in slowing down the timing and increasing instability than this could be shaping up to be a major event tomorrow. IF NAM were to verify than there would also be and increased possibility of a few significant long tracked tornadoes. (most likely in Central AL/GA)

Also, one more thing to add is watch and see if winds can get completely southerly leading to better dewpoints and instability indicated by NAM.

Last Edit: Feb 16, 2008 21:13:41 GMT -6 by futuremet

U of U Atmospheric Science - Focus in Rapid Intensification of Tropical Cyclones

nolasim
Moderator

Posts: 6,930
Location: Algiers-West Bank

Staff Member

Severe Weather Discussion: 2/17/08 Feb 16, 2008 22:19:48 GMT -6

Quote

Post by nolasim on Feb 16, 2008 22:19:48 GMT -6

Beaumont, TX, getting rocked with this big, ugly blob of a system. Not sure if that is the one that may or may not give us a hard time, but it is moving towards the NE with a tail that extends past Corpus Christi, TX. Houston has been getting slammed for the past few hours it seems. Shreveport as well.

We shall see!

"Let's work the problem, people; don't make things worse by guessing!"

Gene Krantz, Flight Director, Apollo 13

SKYSUMMIT
Administrator

President | Director of Operations

Posts: 67,639

Location: Ponchatoula, LA

Staff Member

Severe Weather Discussion: 2/17/08 Feb 16, 2008 22:39:52 GMT -6

Quote

Post by SKYSUMMIT on Feb 16, 2008 22:39:52 GMT -6

Updated MD for Western Louisiana:

MESOSCALE DISCUSSION 0247
NWS STORM PREDICTION CENTER NORMAN OK
1041 PM CST SAT FEB 16 2008

AREAS AFFECTED...PORTIONS SWRN/S-CENTRAL THROUGH NRN LA...SERN
AR...EXTREME WRN MS.

CONCERNING...TORNADO WATCH 59...

VALID 170441Z - 170615Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 59 CONTINUES.

POTENTIAL FOR SVR WIND AND A FEW TORNADOES PERSISTS WITH BAND OF
TSTMS MOVING EWD ACROSS WW AREA. THIS ACTIVITY MAY ACCELERATE
AMIDST STRENGTHENING DEEP-LAYER WINDS. AS PARENT TROUGH CONTINUES
TO EJECT NEWD INTO OK...AND ASSOCIATED GRADIENT FLOW ENHANCEMENTS
SPREAD ACROSS REGION...POTENTIAL FOR DAMAGING GUSTS MAY INCREASE.
DURING PAST 3 HOURS...500 MB WINDS HAVE STRENGTHENED FROM 55-75 KT
AT CENTRAL LA PROFILER. POTENTIAL FOR DAMAGING WIND INCLUDES SOME
AREAS N AND NE OF EXISTING WW...IN AND NEAR N-CENTRAL/NERN LA.
ANOTHER WW MAY BE REQUIRED FOR THOSE AREAS.

MEANWHILE...NEARLY UNIDIRECTIONAL PROFILES ARE EVIDENT IN
VWP/PROFILER DATA AND RUC SOUNDINGS ABOVE RELATIVELY WEAK/SHALLOW
STABLE LAYER NEAR SFC. THIS SHOULD SUPPORT CONTINUED DOMINANCE OF
LINEAR CONVECTIVE MODE...WITH POTENTIAL FOR BOTH DAMAGING GUSTS AND
BRIEF TORNADOES MAXIMIZED LOCALLY INVOF BOW/LEWP FEATURES. MUCAPES
AROUND 1000 J/KG STILL ARE EVIDENT ACROSS THIS AREA...THOUGH RUC
FCST SOUNDINGS INDICATE MLCAPES HAVE DROPPED TO BELOW 200 J/KG
BECAUSE OF WEAK LAPSE RATES AND STABLE AREAS IN LOW LEVELS.

LCH IS LAUNCHING RAOB AHEAD OF CONVECTIVE BAND TO SAMPLE PROXIMITY
INFLOW AIR MASS ACROSS SWRN LA.

..EDWARDS.. 02/17/2008

Buying or Selling Real Estate?--->scottguidry.com
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Scott Guidry, Realtor, ABR, AHWD, AWREP, C2EX
Click HERE To Download My FREE MLS Touch App!
NWS COOP ID: 16-7425-08
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futuremet
Meteorologist

Posts: 1,430

Severe Weather Discussion: 2/17/08 Feb 16, 2008 22:39:55 GMT -6

Quote

Post by futuremet on Feb 16, 2008 22:39:55 GMT -6

As Zack had said earlier, after looking at all the thermodynamics and helicities/wind shear this could be a big bust or big severe event. It all still depends on the amount of instability. In Texas, many area in the mdt risk didn't verify b/c cap inversion/lack of instability. I'm done trying to figure this one out. I'll wait and see now how everything plays out.

U of U Atmospheric Science - Focus in Rapid Intensification of Tropical Cyclones

nolasim
Moderator

Posts: 6,930
Location: Algiers-West Bank

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Severe Weather Discussion: 2/17/08 Feb 16, 2008 23:19:25 GMT -6

Quote

Post by nolasim on Feb 16, 2008 23:19:25 GMT -6

futuremet said:

As Zack had said earlier, after looking at all the thermodynamics and helicities/wind shear this could be a big bust or big severe event. It all still depends on the amount of instability. In Texas, many area in the mdt risk didn't verify b/c cap inversion/lack of instability. I'm done trying to figure this one out. I'll wait and see now how everything plays out.

It's definitely moving NE, and Lake Charles is about to experience it. The tail that extends to Corpus Christi dies out at that point, however, and I think it may move as far as Lafayette and perhaps Baton Rouge, but unless some training develops from that "tail," I think we're going to get away with it and have a sunny day tomorrow.

This is your most amateur forecast from the Jimster!!

"Let's work the problem, people; don't make things worse by guessing!"

Gene Krantz, Flight Director, Apollo 13

Zack Fradella
Administrator

Chairman | Founder

Posts: 8,547

Staff Member

Severe Weather Discussion: 2/17/08 Feb 17, 2008 0:00:29 GMT -6

Quote

Post by Zack Fradella on Feb 17, 2008 0:00:29 GMT -6

I am going to cancel the storm chase. It looks like this will be widespread enough that we will see just as much straight-line winds as every place else. Not much of a tornado threat with the lack of instability.

We will have to wait a little longer for a good tornado chase in the Ms Valley. I am dying for March and April for the big Ms tornado outbreaks.

Zack Fradella
FOX 8 Meteorologist
StormCast - Gulf Coast Weather Founder

For Regular Weather Updates
Like Me On Facebook
Meteorologist Zack Fradella
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Severe Weather Discussion: 2/17/08

Post by ndg on Feb 16, 2008 16:50:31 GMT -6

Post by tracker1 on Feb 16, 2008 17:08:23 GMT -6

Post by tracker1 on Feb 16, 2008 17:27:57 GMT -6

Post by Zack Fradella on Feb 16, 2008 17:51:52 GMT -6

Post by tracker1 on Feb 16, 2008 18:03:24 GMT -6

Post by futuremet on Feb 16, 2008 19:18:09 GMT -6

Post by tracker1 on Feb 16, 2008 19:50:48 GMT -6

Post by tracker1 on Feb 16, 2008 20:31:24 GMT -6

Post by strato474 on Feb 16, 2008 20:36:29 GMT -6

Post by futuremet on Feb 16, 2008 20:44:10 GMT -6

Post by nolasim on Feb 16, 2008 22:19:48 GMT -6

Post by SKYSUMMIT on Feb 16, 2008 22:39:52 GMT -6

Post by futuremet on Feb 16, 2008 22:39:55 GMT -6

Post by nolasim on Feb 16, 2008 23:19:25 GMT -6

Post by Zack Fradella on Feb 17, 2008 0:00:29 GMT -6

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