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October 12-13th "Potential" Severe Outbreak


patrick7032

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Don't set yourself up for depression tomorrow night by using a "fluke" like November 7th as a guideline. <Yoda Voice> Only sadness will you find.</Yoda Voice>

ha yeah, I was 75% joking... that's one of those days you blaspheme by comparing to any other setup. Also, someone has definitely been whispering that in my ear in a raspy voice about this whole trough for a few days now... just couldn't place it until now. :lol:

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Cantore is on the hype machine for Sat outbreak. I'm sorta perplexed what he's seeing. If anything SPC seems to be highlighting the wind potential.. as they should.

Just looked at the 12z GFS. The shear is good but the instability is still lacking and it's tied to the front. (that's in regard to 'nados)

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Surprised no mention of the 12z NAM ... almost fully onboard with the GFS and Euro for Saturday

Hell it's better than the GFS...moisture and instability actually align well in KS/OK all the way up to IA because of less veering at 850mb. It also doesn't build the ridge as much as the GFS/Euro do. That will be key. If the NAM strength of the ridge verifies, Saturday becomes an full order of magnitude more interesting than what I've been thinking up to this point.

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Noticed something interesting on the GFS Bufkit soundings and data. Although the main dryline looks to stay west of the state line...a pre-frontal trough looks to pass through KTCC around noon-1pm and through CVS around 3pm. LBB is looking stronger on the shear now...but still like the AMA to C36 (Guymon) area.

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FWIW...dewpoints have not started their usual mixing drop. In fact they have increased across much of west central Texas...with 68-70 degree dewpoints across almost my entire CWA...stretching all the way to Interstate 20. We even had dense fog earlier this morning...a rare event for this area.

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Copy/paste of the bulk of my discussion regarding the tornado potential: http://www.ustornadoes.com/2012/10/11/tornado-threat-forecast-oct-12-13-2012/

Slower storm motion, more isolated activity and better low-level directional shear make Friday a safer bet than Saturday with regards to the tornado potential. Both days will have low to moderate CAPE, but earlier clouds and rain could hinder activity in the Midwest on Saturday. Friday is missing a solid surface low, which would help back the winds at the surface, but right now it looks like the surface winds will already be out of the south/south-southeast within the risk area, so it is not as critical to have the surface low in this case. Some cloudiness could limit the heating potential within the risk area, but there appears to be sufficient instability even with the cloud cover to allow for tornadoes. Additional backing of the surface winds provides a low threat near the warm front in north-central Oklahoma and southwestern Kansas, but storms may struggle to form in the warm sector and could quickly slide north of the warm front after they form, making the potential very limited.

Saturday will have a stronger wind field compared to Friday, and while it does look impressive from a general severe weather perspective, the directional shear could be lacking, limiting storm rotation and tornado potential. It looks more like a potential severe wind outbreak as a squall line develops, with isolated tornado potential within the squall and with any supercells that could form ahead of the squall line. The greatest potential appears to be in southern Iowa, northwestern Missouri and far eastern Kansas. If the parameters come together better than expected on Saturday, the tornado potential could increase. A tornado outbreak is not out of the question, but the setup isn’t clear enough to make such a call at this time.

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Based off of today's Mesoanalaysis...the NAM seems to have the best "idea" and would use it's instability parameters for tomorrow. As such...it shows the highest instability west of I-27...generally 2 tiers of counties either side of the AMA/LBB CWA border... and it continues to show around 2500 j/kg with LI's of -9. Currently the NAM is still under-doing instability...as currently I have 3500-4000 near my CWA borders.

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The 15Z SREF holds serve and seems to show the best composite indices (supercell comp., sigtor) between AMA and the TX/NM border, with 0-1 and 0-3 km SRH values rapidly increasing between 21Z and 00Z anywhere from AMA up to the TX/OK panhandle border. Looks like initiation occurs on the border west of NE and then zips up to the northeast toward Dumas/Perryton. I'm really liking AMA as a "watch-and-wait" target for tomorrow, plus it will have good access to head a bit further west/south if need be. They're also putting out less than a 50% probability of at least 500 J/kg of CAPE up to the OK/TX panhandle border... instability (and dewpoints >= 60F) struggle to really get past Dumas-Pampa.

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Springfield, MO had this to say about Saturday in their afternoon AFD today: (their entire writeup is very long)

THIS SYNOPTIC PATTERN HAS A FAIRLY STRONG DYNAMIC SETUP WITH

HELICITY VALUES ON THE ORDER OF OF 300 TO 400 M2S2 AND BULK SHEAR

RANGING FROM 50 TO 70 KTS. HOWEVER...BOTH MOST UNSTABLE AND

SURFACE BASED CAPE VALUES ARE NOT OVERLY IMPRESSIVE...RANGING FROM

800 TO 1500 J/KG (MOST UNSTABLE) TO 500 TO 1000 J/KG FOR SURFACE

BASED CAPE. SURFACE WINDS ARE FORECAST GENERALLY FROM THE

SOUTHWEST WHICH IS ALSO NOT FAVORABLE FOR TORNADO DEVELOPMENT.

GIVEN THE UPPER LEVEL DYNAMICS...HELICITY...AND WIND SHEAR...WE

BUT MAY STILL SEE SOME MESOVORTICES DEVELOP WELL ABOVE THE

SURFACE.

GIVEN THE ABOVE...AT THIS POINT THE LIKELY STORM MODE APPEARS TO BE

OF A LINEAR/QLCS TYPE OVER EASTERN KANSAS AND THE MISSOURI OZARKS.

BUT DUE TO THE PATTERN IN SOME OF THE MODELS I AM A BIT CONCERNED

ABOUT A POSSIBLE SPLIT OF ENERGY FROM A DYNAMIC PERSPECTIVE WITH A

SEPARATE VORTMAX ON THE SOUTHERN SIDE OF THE TROF. THIS MAY HELP

GENERATE A MORE MIXED MODE QLCS/POTENTIAL SUPERCELL SETUP FORMATION

OVER NORTHERN ARKANSAS AND THE FAR SOUTHERN BORDER COUNTIES OF

MISSOURI WHILE A QLCS/SQUALL LINE SETUP PREVAILS TO THE NORTH...OVER

THE REST OF THE CWA. AT THIS POINT THIS EVENT IS STILL OVER TWO

DAYS AWAY SO IT IS PRUDENT TO SEE EXACTLY HOW IT EVOLVES BEFORE

MAKING ANY SPECIFIC CONCLUSIONS ON STORM MODE TO THE SOUTH.

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Springfield, MO had this to say about Saturday in their afternoon AFD today: (their entire writeup is very long)

THIS SYNOPTIC PATTERN HAS A FAIRLY STRONG DYNAMIC SETUP WITH

HELICITY VALUES ON THE ORDER OF OF 300 TO 400 M2S2 AND BULK SHEAR

RANGING FROM 50 TO 70 KTS. HOWEVER...BOTH MOST UNSTABLE AND

SURFACE BASED CAPE VALUES ARE NOT OVERLY IMPRESSIVE...RANGING FROM

800 TO 1500 J/KG (MOST UNSTABLE) TO 500 TO 1000 J/KG FOR SURFACE

BASED CAPE. SURFACE WINDS ARE FORECAST GENERALLY FROM THE

SOUTHWEST WHICH IS ALSO NOT FAVORABLE FOR TORNADO DEVELOPMENT.

GIVEN THE UPPER LEVEL DYNAMICS...HELICITY...AND WIND SHEAR...WE

BUT MAY STILL SEE SOME MESOVORTICES DEVELOP WELL ABOVE THE

SURFACE.

GIVEN THE ABOVE...AT THIS POINT THE LIKELY STORM MODE APPEARS TO BE

OF A LINEAR/QLCS TYPE OVER EASTERN KANSAS AND THE MISSOURI OZARKS.

BUT DUE TO THE PATTERN IN SOME OF THE MODELS I AM A BIT CONCERNED

ABOUT A POSSIBLE SPLIT OF ENERGY FROM A DYNAMIC PERSPECTIVE WITH A

SEPARATE VORTMAX ON THE SOUTHERN SIDE OF THE TROF. THIS MAY HELP

GENERATE A MORE MIXED MODE QLCS/POTENTIAL SUPERCELL SETUP FORMATION

OVER NORTHERN ARKANSAS AND THE FAR SOUTHERN BORDER COUNTIES OF

MISSOURI WHILE A QLCS/SQUALL LINE SETUP PREVAILS TO THE NORTH...OVER

THE REST OF THE CWA. AT THIS POINT THIS EVENT IS STILL OVER TWO

DAYS AWAY SO IT IS PRUDENT TO SEE EXACTLY HOW IT EVOLVES BEFORE

MAKING ANY SPECIFIC CONCLUSIONS ON STORM MODE TO THE SOUTH.

That would be a dangerous setup...

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AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE AMARILLO TX

310 PM CDT THU OCT 11 2012

TOMORROW...STILL LOOKS LIKE TWO SEPARATE OPPORTUNITIES FOR

THUNDERSTORMS...THE FIRST WITH STORM DEVELOPMENT TOMORROW

AFTERNOON. MANY IFS REMAIN FOR AFTERNOON CONVECTIVE INITIATION...THE

BIGGEST OF WHICH IS IF AND WHEN LOW CLOUDS TOMORROW MORNING WILL

ERODE. NAM AND GFS BOTH SHOW A PERSISTENT LOW LEVEL DECK CONTINUING

THROUGH MUCH OF THE DAY. IF THESE CLOUDS PERSIST THROUGH AT LEAST MID

AFTERNOON...THEN IT IS UNLIKELY THAT WE WILL REACH THE CONVECTIVE

TEMPERATURE...THUS MAKING THE AFTERNOON ROUND OF CONVECTION UNLIKELY.

IF CLOUDS ERODE BY MID DAY...THAN WE COULD GET ENOUGH

INSOLATION...COMBINED WITH SOUTHERLY FLOW TO EASILY REACH THE

CONVECTIVE TEMPERATURE. AS WITH THE LAST SEVERAL MODEL RUNS...CAPE

VALUES OF NEAR 1500 J/KG AND NEAR 50 KT OF BULK SHEAR WILL PROVIDE A

FAVORABLE ENVIRONMENT FOR SUPERCELL DEVELOPMENT THROUGH THE AFTERNOON

AND EARLY EVENING HOURS. AT THIS POINT...THINK THAT THE MOST LIKELY

SOLUTION IS THAT THE CLOUDS WILL PERSIST...LIMITING IF NOT PRECLUDING

ALL TOGETHER AFTERNOON CONVECTIVE INITIATION.

Certainly not an easy chase tomorrow. :unsure:

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AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE FORT WORTH TX

341 PM CDT THU OCT 11 2012

.DISCUSSION...

SATURDAY THROUGH SUNDAY...THE SOUTHERN CA UPPER LOW IS EXPECTED TO

CONTINUE TO MOVE NORTHEAST THROUGH THE PERIOD WITH THE CENTER OF

THE CLOSED CIRCULATION EXPECTED TO MOVE ALONG THE KANSAS/NEBRASKA

BORDER SATURDAY AFTERNOON. WHILE THE CENTER OF THE CLOSED LOW WILL

REMAIN TOO FAR NORTH TO HAVE A DIRECT IMPACT ON NORTH

TX...GUIDANCE INDICATES THAT A SIGNIFICANT PIECE OF ENERGY...A

SHORTWAVE TROUGH EMBEDDED IN THE UPPER LOW...WILL MOVE OVER THE

SOUTHERN PLAINS SATURDAY AFTERNOON THROUGH THE EVENING HOURS. THIS

PIECE OF ENERGY WILL PRIMARILY SPREAD LARGE SCALE FORCING FOR

ASCENT NORTH OF THE RED RIVER...HOWEVER IT IS ALSO EXPECTED TO

SHARPEN UP A PACIFIC TYPE COLD FRONT AND SEND IT SOUTHEAST TOWARDS

NORTH TX SATURDAY AFTERNOON. THE ENHANCEMENT OF THE FRONT SHOULD

RESULT IN STRONG MESOSCALE FORCING FOR ASCENT OUT AHEAD OF THE

FRONT RESULTING IN THE INITIATION OF A BROKEN LINE OF STORMS BY

LATE SATURDAY AFTERNOON JUST WEST OF THE CWA. THERE WILL ALSO

LIKELY BE SOME ENHANCED UPWARD VERTICAL MOTIONS SUPERIMPOSED OVER

THE NORTHWEST PORTIONS OF THE CWA SATURDAY AFTERNOON WITH THE

RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET STREAK IN PLACE.

BETWEEN FORCING FOR ASCENT ASSOCIATED WITH THE BOUNDARY AND UPPER

LEVEL SUPPORT IN THE FORM OF THE THERMALLY DIRECT AGEOSTROPHIC JET

STREAK CIRCULATION...CONFIDENCE IN THUNDERSTORM ACTIVITY SATURDAY

AFTERNOON THROUGH THE EVENING HOURS HAS INCREASED WITH THIS

FORECAST PACKAGE. WENT AHEAD AND BUMPED POPS INTO THE 50 TO 60

PERCENT RANGE AS A RESULT.

OVERALL CONFIDENCE IN AN ORGANIZED STORM MODE DURING THE PERIOD

HAS INCREASED AS WELL. MODEL CONSENSUS INDICATES THAT INSTABILITY

WILL BE SOMEWHAT LIMITED OUT AHEAD OF THE FRONT...PRIMARILY DUE TO

PERSISTENT STRATOCUMULUS ASSOCIATED WITH DEEP MOISTURE AND

ISENTROPIC LIFT AHEAD OF THE FRONT. EVEN WITH LIMITED

HEATING...GUIDANCE STILL FORECASTS AROUND 1500 J/KG OF CAPE ALONG

AND SOUTHEAST OF THE FRONT SATURDAY AFTERNOON AND EVENING. WHILE

THERE IS SOME CONCERN REGARDING AVAILABLE POTENTIAL ENERGY FOR

CONVECTION...CONFIDENCE IS HIGH IN STRONG DEEP LAYER SHEAR IN

PLACE WITH THE PRESENCE OF THE JET STREAK OUT AHEAD OF SATURDAYS

SHORTWAVE TROUGH. ASSUMING THERES SUFFICIENT INSTABILITY TO

SUPPORT UPDRAFT STRENGTH...FAVORABLE VALUES OF DEEP LAYER SHEAR

AND STRONG FORCING FOR ASCENT ALONG THE FRONT SHOULD SUPPORT A

LINEAR STORM MODE SATURDAY AFTERNOON THROUGH THE OVERNIGHT HRS

ACROSS NORTH TX. THERE MAY BE A WINDOW FOR DISCRETE CONVECTION

UPON THUNDERSTORM INITIATION ALONG THE FRONT SATURDAY

AFTERNOON...HOWEVER THIS IS EXPECTED TO OCCUR NORTHWEST OF OUR CWA

AT THIS TIME. AFTER AN INITIALLY BROKEN/DISCRETE STORM

MODE...EXPECT CONSOLIDATION INTO A SQUALL LINE WHICH SHOULD ALLOW

STORMS TO MOVE EAST OFF THE FRONT AND THROUGH THE CWA.

ASSUMING A LINE OF THUNDERSTORMS HAS DEVELOPED BY 00Z...THIS LINE

IS EXPECTED TO RESIDE OVER THE FAR NORTHWESTERN CWA AT

00Z...MOVING EAST-NORTHEAST THEREAFTER. THE LOW LEVEL JET SHOULD

RAMP UP AGAIN AFTER SUNSET WHICH SHOULD ACTUALLY BE FAVORABLE FOR

THE DOWNSTREAM PROPAGATION OF THE SQUALL LINE. THE LOW LEVEL JET

WILL ENHANCE LOW LEVEL SHEAR RELATIVE TO THE CONSOLIDATED COLD

POOL ENHANCING VERTICAL MOTIONS ALONG THE GUST FRONT AS IT MOVES

EAST. THIS SQUALL LINE IS EXPECTED TO APPROACH THE DFW AREA AROUND

MIDNIGHT AND THEREAFTER IT SHOULD BE WEAKENING AS THE UPPER LEVEL

JET STREAK PULLS OFF TO THE NORTHEAST AND SEVERAL HOURS OF COOLING

REDUCE OVERALL DOWNSTREAM INSTABILITY.

SEVERE WEATHER HAZARDS: SATURDAY AFTERNOON THROUGH

MIDNIGHT...THIS LINE OF STORMS SHOULD BE CAPABLE OF PRODUCING

SEVERE WEATHER...WITH THE PRIMARY THREAT BEING IN THE FORM OF

DAMAGING STRAIGHT LINE WINDS. LARGE HAIL IS ALSO POSSIBLE BUT

WOULD BE MORE LIKELY ASSOCIATED WITH EMBEDDED SUPERCELL STRUCTURES

AND SHOULD NOT BE AS WIDESPREAD A THREAT AS DAMAGING WINDS. EXPECT

THE LINE OF STORMS TO BE CHARACTERIZED BY A FEW BOWING STRUCTURES

IN WHICH ANY DAMAGING WINDS SHOULD BE MAXIMIZED. WHILE A HIGH END

DAMAGING WIND THREAT IS NOT EXPECTED...GUSTS OF 60 TO 70 MPH WOULD

SEEM POSSIBLE WITHIN ANY BOWING STRUCTURE MOVING THROUGH THE AREA

SATURDAY AFTERNOON THROUGH THE EVENING HOURS. AFTER MIDNIGHT THE

LOSS OF DEEP LAYER SHEAR AND MARGINAL DOWNSTREAM INSTABILITY

SHOULD ALLOW THE SQUALL LINE TO BECOME OUTFLOW DOMINATED GREATLY

REDUCING ITS POTENTIAL TO PRODUCE DAMAGING WINDS. OF COURSE THE

EXACT EVOLUTION OF THIS SQUALL LINE IS HIGHLY DEPENDENT UPON

MESOSCALE (SHORT TERM AND LOCAL) FORECAST DETAILS WHICH WILL NOT

BE WELL RESOLVED UNTIL SATURDAY MORNING. A SIGNIFICANT CHANGE IN

THE TRACK OR STRENGTH OF THE UPPER LOW AND ASSOCIATED SHORTWAVE

TROUGH WILL HAVE A LARGE IMPACT ON THIS FORECAST.

CAVANAUGH

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That's what I keep telling myself, but then I keep seeing the quote in your signature and swallowing. lol.

I'm not sure what I'd do if I lived out there. I'd either be a bum who only chased tornadoes or get really sick of driving around for nothing after a while. At least you guys are in school doing something greater for the good of mankind, or something.

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The 15Z SREF holds serve and seems to show the best composite indices (supercell comp., sigtor) between AMA and the TX/NM border, with 0-1 and 0-3 km SRH values rapidly increasing between 21Z and 00Z anywhere from AMA up to the TX/OK panhandle border. Looks like initiation occurs on the border west of NE and then zips up to the northeast toward Dumas/Perryton. I'm really liking AMA as a "watch-and-wait" target for tomorrow, plus it will have good access to head a bit further west/south if need be. They're also putting out less than a 50% probability of at least 500 J/kg of CAPE up to the OK/TX panhandle border... instability (and dewpoints >= 60F) struggle to really get past Dumas-Pampa.

I completely agree.

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AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE LUBBOCK TX

350 PM CDT THU OCT 11 2012

AS HEIGHTS FALL AHEAD OF THIS LOW BY MID AFTERNOON...DISCRETE CELLS

WILL HAVE THE INITIAL CHANCE TO COMMENCE. BACKING LOW-LEVEL WINDS

AND INCREASINGLY CLOCKWISE-CURVED HODOGRAPHS WILL SUPPORT THE CHANCE

FOR AN ISOLATED TORNADO. WHILE A FEW SURFACE-BASED STORMS MAY BE

ABLE TO GENERATE TO THE WEST NEAR THE NEW MEXICO STATE LINE...WHERE

BETTER MIXING WILL TAKE PLACE...A RESIDUAL COOLER AND MORE STABLE

BOUNDARY LAYER WILL LIKELY CAUSE STORMS TO BE ELEVATED IN NATURE.

THIS WILL LEAD TO PRIMARILY A HAIL THREAT AS CONVECTIVE WIND GUSTS

MAY STRUGGLE TO REACH THE SURFACE. HEAVY RAIN WILL ALSO BE A

POSSIBILITY WHERE STORMS TRAIN.

&&

.LONG TERM...

CONVECTION IS EXPECTED TO CONTINUE THROUGHOUT THE EVENING AND

OVERNIGHT HOURS FRIDAY INTO SATURDAY. THE MOST WIDESPREAD COVERAGE

IS EXPECTED TO BE BETWEEN 00Z AND 06Z. MAXIMUM LIFT FROM THE CLOSED

LOW/TROUGH CONTINUES TO BE PROGGED NORTH OF THE AREA. THE BEST

THERMODYNAMIC PARAMETERS WILL BE CENTERED OVER THE SOUTHWESTERN

TEXAS PANHANDLE AND VERY IMPRESSIVE FOR OCTOBER STANDARDS. AS CLOUDS

CLEAR OUT...CAPES IN EXCESS OF 1000 J/KG WILL BE SEEN NEAR THE

TEXAS...NEW MEXICO STATE LINE. INSTABILITY WILL BE LESS AND CIN WILL

BE HIGHER EAST OF HERE WITH CLOUD COVER PERSISTING FOR A GOOD

PORTION OF THE DAYTIME. THE BEST LOW LEVEL HELICITY AND SHEAR

VECTORS WILL AGAIN BE LOCATED OVER THE SOUTHWESTERN TEXAS PANHANDLE.

MODEL HODOGRAPHS DO SHOW SOME LOW LEVEL TURNING BUT IS STILL RATHER

WEAK. THOUGH IT IS WEAK...IT IS ENOUGH TO NOT BE IGNORED FOR A

TORNADO THREAT. HOWEVER...ABOVE THIS LOW LAYER...STRONG SHEAR WILL

EXIST LENDING TO ORGANIZED SEVERE CONVECTION. LARGE HAIL IS STILL

THE PRIMARY THREAT FROM THIS CONVECTION. WOULD STILL EXPECT MORE

DISCRETE CELLS OVER THE SOUTHWESTERN PANHANDLE AND SOUTH PLAINS AND

MORE LINEAR FEATURES FARTHER NORTH IN THE WESTERN AND CENTRAL

PANHANDLE. STORM CHANCES WILL SHIFT EAST DURING THE EVENING AND

OVERNIGHT WITH THE DEVELOPMENT OF A LOW LEVEL JET. THIS LLJ WILL BE

MAXIMIZED OVER THE ROLLING PLAINS AT IMPRESSIVE SPEEDS NEAR 50KT.

ELEVATED INSTABILITY WILL ALSO CONTINUE THROUGH THE NIGHT WITH THIS

LLJ.

A CLOSED LOW SOLUTION PERSISTING INTO SATURDAY APPEARS MORE

PLAUSIBLE WITH THE LATEST MODEL RUNS. UPPER LEVEL LIFT FROM THIS LOW

WILL BE TRAILING OVER THE ROLLING PLAINS SATURDAY MORNING AND

AFTERNOON. STORM REDEVELOPMENT WILL BE POSSIBLE OVER THIS AREA

DURING THIS TIME PERIOD. A STRONG UPPER LEVEL JET WILL BE MOVING

DIRECTLY OVERHEAD ON SATURDAY. THIS LIFT MAY OBTAIN SOME ASSISTANCE

FROM A PACIFIC FRONT SWEEPING INTO THE ROLLING PLAINS. THIS FRONT IS

EXPECTED TO SIGNIFICANTLY SLOW OR EVEN STALL OUT BY THE AFTERNOON.

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