Oklahoma Severe Weather Discussion - May 2011

[Boo1083]

I love this blog site! Do you give blog imformation on southeast Oklahoma too? I'm in Poteau, and I like to be ahead of severe weather !

[Thunder]

So, nothing to expect for the 7th, which is today? *sighs* The time seem to have gotten slower and slower, but it could be the storms keep pushing further days away. All we can do is wait, wait, and wait. It is like having that feeling, "Will it be my house this year?"

[venture]

SPC 4-8 Day Outlook is out now... Lot of the things I picked up on earlier this evening are mentioned. They seem to like the consistency of the ECMWF model which slows thing down a bit...Keeps Tuesday as an isolated day (as previously thought) and a potential outbreak for Wednesday.

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0353 AM CDT SAT MAY 07 2011

VALID 101200Z - 151200Z

...DISCUSSION...
ATTENTION IN THE MEDIUM RANGE WILL REVOLVE AROUND THE EJECTION OF
THE WRN STATES UPPER TROUGH INTO THE MID-SECTION OF THE COUNTRY.
GUIDANCE HAS DECIDEDLY BECOME HIGHLY VARIED AND CONFIDENCE HAS
DECREASED...ALTHOUGH 00Z ECMWF SEEMS TO BE THE MOST CONSISTENT.

THE LEAD WAVE THAT CRESTS THE ROCKIES ON MONDAY WILL CONTINUE ENE
ACROSS THE DAKOTAS ON TUESDAY. THIS MAY HELP SUPPORT STRONG TO
SCATTERED SVR STORMS OVER THE UPR MS VLY/ERN DAKOTAS ON DAY 4...TOO
SPARSE FOR A MEDIUM RANGE OUTLOOK. MEANWHILE...HOT BOUNDARY
LAYER...WEAK HEIGHT FALLS AND CONVERGENCE ALONG THE DRYLINE MAY
YIELD ISOLD SVR STORMS OVER SW OK INTO W TX ON TUESDAY...THOUGH
CONFIDENCE IS NOT HIGH...ESPECIALLY GIVEN STRENGTH OF THE EML.

ECMWF WOULD LEND CREDENCE TO A HIGHER POTENTIAL FOR A HIGHER-END SVR
EPISODE ON WEDNESDAY AS PRIMARY TROUGH EJECTS INTO THE CNTRL/SRN
PLAINS. SFC LOW SHOULD REMAIN ON THE CO/KS BORDER...ALLOWING
DRYLINE TO SET UP FROM W KS INTO NW TX. COOLING MID-LEVEL
TEMPERATURES AND ASCENT/MOISTENING SHOULD WEAKEN THE CAP AND
ORGANIZED STORMS SHOULD EVOLVE WEDNESDAY AFTN/EVE ACROSS CNTRL
KS...WRN/CNTRL OK AND NCNTRL/NWRN TX WITH ALL FACETS OF SVR WEATHER
POSSIBLE.

BEYOND WEDNESDAY...FLOW REGIME EXHIBITS PARTICULARLY LOW
PREDICTABILITY.

[Thunder]

I get the feeling we are going to have an EF5 sweeping through the metro. Possibly an EF6. Maybe higher.

[PennyQuilts]

Maybe an EF7!

[Bostonfan]

Can we keep this thread informational? Maybe make an "I hope for death and destruction" thread somewhere else? My God.

[Thunder]

We don't want death and destruction. Its just the history that happens after a strong La Nina. Looking at the SE, now its our turn, so it is scary. Reflect back on May 3rd, 1999.

[venture]

Can we keep this thread informational? Maybe make an "I hope for death and destruction" thread somewhere else? My God.

Will have to side with Bostonfan here for this. We could be looking at a high end event for us that yes, could involve a tornado outbreak, so let's not get anyone freaked out if at all possible. :-)

[bandnerd]

I think we've all reflected enough. Let's be prepared without panicking or causing a panic.

[Andrew4OU]

Uhm... seriously, Thunder? Good gosh.

[venture]

Updated Day 2 for Sunday...

...SRN PLAINS...
A CONDITIONAL THREAT OF SUPERCELLS CAPABLE OF VERY LARGE HAIL WILL
EXIST. STRONG CONVECTIVE INHIBITION WILL GENERALLY LIMIT DEVELOPMENT
THROUGH MUCH OF THE AFTERNOON/EVENING. HOWEVER...HEATING/MIXING WEST
OF THE DRYLINE CHARACTERIZED BY HOT TEMPERATURES IN THE MID 90S TO
NEAR 100 F SUGGEST THE POSSIBILITY THAT THE CAP MAY ERODE IN A
NARROW CORRIDOR ACROSS WRN/CNTRL OK SWD INTO TX AS A WEAK UPPER
TROUGH/SUBTLE VORT MAX APPROACH THE AREA. GIVEN VERY STEEP MID LEVEL
LAPSE RATES IN EXCESS OF 8.5 C/KM...AND DEEP LAYER SHEAR VECTORS
ORIENTED PERPENDICULAR TO THE DRYLINE...A FEW HIGH-BASED SUPERCELLS
MAY DEVELOP. ALTHOUGH A TORNADO CANNOT BE RULED OUT...HIGH-BASED
NATURE SUGGESTS LOW PROBABILITIES OF THIS OCCURRING.

[venture]

Severe threat today is mostly for hail...



...SRN PLAINS...

CONDITIONAL RISK OF SEVERE STORMS IS FORECAST ALONG THE DRYLINE
SUNDAY...PRIMARILY FROM SWRN OK INTO SWRN TX. LATEST NAM/GFS
GUIDANCE HAS GRADUALLY EASED AWAY FROM CONVECTIVE DEVELOPMENT ALONG
THIS ZONE THE LAST SEVERAL MODEL RUNS. EARLY EVENING SATELLITE
IMAGERY DOES SUGGEST A FEW MINOR IMPULSES EMBEDDED WITHIN THE FLOW
ACROSS THE SWRN U.S. WHICH SHOULD APPROACH THE DRYLINE BEFORE THEY
WEAKEN. THIS NEUTRAL-WEAK LARGE SCALE SUPPORT MAY ALLOW ISOLATED
THUNDERSTORMS TO DEVELOP AS TEMPERATURES SOAR INTO THE 90S TO NEAR
100F. ANY STORMS THAT EMERGE ACROSS THIS REGION COULD CERTAINLY
PRODUCE LARGE HAIL BEFORE WEAKENING BY 03Z.

[venture]

Pretty much steady as she goes for Wednesday. The Day 4-8 SPC Discussion is below. Looking at the models tonight...ECMWF is still favored (per SPC) and GFS and NAM are a bit different, but really not by a lot. NAM only goes out 84 hours, so that takes us to Weds morning. We'll need to wait for late morning to get more specific for Wednesday evening.

Comparing GFS and ECMWF, GFS kicks things through faster than ECMWF. At 7PM Wednesday, GFS has the southern Low kicking up through SW Nebraska, whereas ECMWF has it located in SW/SC Kansas. Either way, dryline will be across western OK with a cold front over extreme NW OK. Some storms may be on going early on Wednesday, so those could come into play. However, storms will fire in an environment that will have some cap, but be very breakable. At this point, storms will likely be severe with very large hail and tornadoes as the main risks.

Forecast Sounding for Wednesday evening showing an extremely unstable environment.



-------------------
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0330 AM CDT SUN MAY 08 2011

VALID 111200Z - 161200Z

...DISCUSSION...
SRN PORTIONS OF THE WRN STATES UPPER TROUGH WILL BE IN THE PROCESS
OF EJECTING ENE FROM THE SRN ROCKIES INTO THE CNTRL/SRN PLAINS BY
TUESDAY NIGHT AND WEDNESDAY /DAY 4/. 00Z ECMWF SOLUTION IS
PREFERRED IN MAINTAINING STRONGER HEIGHT FALLS/JET AS IT MOVES INTO
KS/OK/W TX WITH TRIPLE POINT LIKELY EVOLVING OVER SW KS WEDNESDAY
AFTN. MAGNITUDE OF FORCING...COOLING MID-LEVEL TEMPS AND 50-60 KTS
OF SWLY MID-LEVEL FLOW ASSOCIATED WITH THE TROUGH SHOULD LEAD TO
ORGANIZED SEVERE STORMS FROM KS/NEB BORDER SWD INTO NRN TX. THESE
STORMS WILL THEN TRANSLATE ENE TOWARD SE NEB...ERN PARTS OF KS/OK
AND NCNTRL TX WEDNESDAY NIGHT. AT THIS POINT...DAY 4 APPEARS TO BE
SETTING UP FOR AN ACTIVE SEVERE EVENT WITH ALL FACETS OF SEVERE
WEATHER POSSIBLE.

[venture]

Some sporadic CU trying to develop along the dryline, but nothing major to worry about right now.

[Thunder]

Some sporadic CU trying to develop along the dryline, but nothing major to worry about right now.

Will they be capable of spawning those swirling monsters?

[venture]

MESOSCALE DISCUSSION 0700
NWS STORM PREDICTION CENTER NORMAN OK
0357 PM CDT SUN MAY 08 2011

AREAS AFFECTED...PORTIONS OF SWRN OK AND WRN PORTIONS OF NORTH TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 082057Z - 082300Z

AN ISOLATED SVR STORM OR TWO COULD DEVELOP ACROSS PORTIONS OF SWRN
OK AND WRN PORTIONS OF NORTH TX.

A DRYLINE CONTINUES TO SHARPEN FROM CNTRL OK INTO WRN PORTIONS OF
NORTH TX...EXTENDING FROM 15 W CHK TO THE RED RIVER 20 W SPS TO 25
ENE SJT AND FARTHER SW INTO SWRN TX. A BROAD MOIST SECTOR EXISTS
EAST OF THE DRYLINE WHERE SFC DEWPOINTS ARE IN THE MIDDLE 60S TO
NEAR 70. OVERLAYING THIS MOISTURE...VERY STEEP MID-LEVEL LAPSE RATES
/APPROACHING DRY ADIABATIC PER 12Z OBSERVED SOUNDINGS AT KOUN AND
KDDC/ IN ASSOCIATION WITH THE STRONG ELEVATED MIXED-LAYER ARE
CONTRIBUTING TO A VERY UNSTABLE AIR MASS EAST OF THE DRYLINE /MLCAPE
VALUES AOA 3000 J PER KG/. THUS FAR...STRONG CAPPING EAST OF THE
DRYLINE IS SUPPRESSING THE DEVELOPMENT.

CONTINUED STRONG INSOLATION OVER THE WRN PERIPHERY OF THE RICH
MOISTURE AXIS AND ERN PERIPHERY OF THE THERMAL AXIS COULD REDUCE
CONVECTIVE INHIBITION SUFFICIENTLY TO SUPPORT THE DEVELOPMENT OF A
THUNDERSTORM OR TWO ALONG AND IMMEDIATELY EAST OF THE DRYLINE. THERE
IS MUCH UNCERTAINTY IN THIS POTENTIAL...OWING TO LACK OF SUPPORT
FROM CONVECTIVE-ALLOWING MODELS AND UNCERTAINTY IN THE DEGREE OF
SUPPRESSION OF CONVECTIVE INHIBITION. HOWEVER...THE PRESENCE OF A
DEVELOPING CUMULUS FIELD NEAR THE DRYLINE...WHERE ENHANCED
CONVERGENCE IS PRESENT AND RAPID REFRESH FORECAST SOUNDINGS INDICATE
CONVECTIVE INHIBITION AOB 25 J/KG...LEND CREDENCE TO THIS THREAT
/ALBEIT SMALL/.

ANY STORM THAT FORMS COULD QUICKLY BECOME SEVERE...GIVEN THE DEGREE
OF POTENTIAL UPWARD BUOYANCY PREVIOUSLY MENTIONED. WHILE
LOW/MID-LEVEL FLOW IS NOT PARTICULARLY IMPRESSIVE...MODERATE
UPPER-LEVEL FLOW COUPLED WITH LARGE STORM DEPTHS WILL YIELD
EFFECTIVE BULK SHEAR MAGNITUDES FROM 35 TO 40 KT TO SUPPORT
SUPERCELLULAR STRUCTURES. THIS WILL ESPECIALLY BE THE CASE IF ANY
STORM IS STEERED INTO THE DEEPER MOISTURE EAST OF THE DRYLINE. DMGG
WINDS AND LARGE HAIL /POTENTIALLY VERY LARGE/ WILL BE THE MAIN
THREATS WITH ANY STORMS. THE ABSENCE OF STRONGER LOW-LEVEL FLOW PER
AREA VWPS IS EXPECTED TO MITIGATE THE TORNADO POTENTIAL. GIVEN THAT
ANY FORCING FOR CONVECTION WILL LARGELY BE TIED TO THE DRYLINE
/WHICH IS EXPECTED TO MAKE LITTLE EWD PROGRESS THROUGH THIS
EVENING/...GIVEN THE CONVECTIVE INHIBITION EAST OF THE DRYLINE...AND
GIVEN ONLY ISOLATED CONVECTIVE COVERAGE...THE SPATIAL EXTENT OF ANY
SEVERE THREAT IS EXPECTED TO BE LOW.

..COHEN.. 05/08/2011

[silvergrove]

When driving home to see my folks in Yukon, I noticed those cumulus clouds towards the west-northwest. They're not really big but they at least are trying!

[venture]

We do have storms attempting to go up now in Caddo County.

[venture]

Bulletin - immediate broadcast requested
severe thunderstorm warning
national weather service norman ok
559 pm cdt sun may 8 2011

the national weather service in norman has issued a

* severe thunderstorm warning for...
Central grady county in central oklahoma...
Eastern caddo county in southwest oklahoma...

* until 645 pm cdt

* at 559 pm cdt...national weather service radar indicated a
severe thunderstorm centered 7 miles southwest of verden...moving
east northeast at 25 mph.

Hazards in the warning include...
Hail up to the size of quarters...
Wind gusts to 60 mph...

* locations in the warning include amber...bridge creek...
Chickasha...laverty...middleberg...ninnekah...norg e...tabler and
verden.

[venture]

Chat room at www.chatokc.com is now up and going.

[silvergrove]

Back in my home away from home in the MLK neighborhood, those clouds to my southwest look rather scary! Looking forward to possible rain though

[venture]

Bulletin - immediate broadcast requested
severe thunderstorm warning
national weather service norman ok
653 pm cdt sun may 8 2011

the national weather service in norman has issued a

* severe thunderstorm warning for...
Cotton county in southwest oklahoma...

* until 730 pm cdt

* at 653 pm cdt...national weather service radar indicated a severe
thunderstorm 7 miles south of devol...moving northeast at 40 mph.

Hazards in the warning include...
Hail up to the size of golf balls...
Wind gusts to 60 mph...

* locations in the warning include cookietown...devol...randlett...
Taylor...temple and walters.

This includes interstate 44 between mile markers 1 and 24.

Lat...lon 3415 9858 3416 9861 3424 9860 3445 9846
3429 9813 3414 9837 3406 9843 3406 9848
time...mot...loc 2353z 228deg 41kt 3412 9853

[venture]

Special weather statement
national weather service norman ok
959 pm cdt sun may 8 2011

okz028-029-090315-
cleveland ok-mcclain ok-
959 pm cdt sun may 8 2011

...significant weather advisory...

This significant weather advisory is for cleveland and mcclain
counties.

At 1000 pm cdt...a strong thunderstorm was located 3 miles east of
criner...moving northeast at 35 mph.

Hazards include...
Hail up to one-half inch...
Wind gusts to 50 mph...

Monitor the weather situation closely and be alert for threatening
weather conditions.

[venture]

New Day 2 Outlook is out for Tuesday. Monday no risk associated as cap is expected to be very strong.

...ERN PARTS OF CNTRL/SRN PLAINS...
REGION WILL REMAIN IN SUSTAINED SLY LOW-LEVEL FLOW THAT WILL
MAINTAIN RELATIVELY RICH BOUNDARY LAYER MOISTURE /SFC DEW POINTS IN
THE 60S/ THROUGH TUESDAY. THIS MOISTURE WILL BE TOPPED BY A STRONG
EML THAT WILL RESULT IN A STRONG CAP...BUT POTENTIALLY VERY STRONG
INSTABILITY GIVEN 8+ DEG C/KM H5-H7 LAPSE RATES.

SECONDARY MID-LEVEL WAVE...EXPECTED TO BEGIN AN ENE TREK TO THE SRN
ROCKIES BY TUESDAY AFTN...WILL RESULT IN WEAKLY DIFLUENT UPR FLOW
REGIME ACROSS THE DRYLINE DURING THE AFTN/EVE. ALTHOUGH STORM
INITIATION CANNOT BE RULED OUT FROM NRN OK INTO CNTRL/ERN
KS...HIGHER PROBABILITIES WILL EXIST FROM CNTRL/SWRN OK INTO THE ERN
EDWARDS PLATEAU OF TX WHERE HOTTEST BOUNDARY LAYER TEMPERATURES
SHOULD EXIST. WIND PROFILES CONSISTING OF VERTICAL SHEAR OF 45-50
KTS...AND THE MAGNITUDE OF LAPSE RATES WILL YIELD SUPERCELLS WITH
LARGE HAIL AND PERHAPS ISOLD TORNADOES/DMGG WIND GUSTS DURING THE
EVENING. ACTIVITY MAY PERSIST INTO LATE EVENING ACROSS ERN OK TO
CNTRL TX WITH AT LEAST ISOLD LARGE HAIL.

MEANWHILE...WRN FRINGES OF EVENING MOISTURE SURGE MAY IGNITE INTO
TSTMS VERY LATE IN THE PERIOD AS THE UPPER TROUGH EDGES TO THE SRN
HIGH PLAINS. THESE STORMS MAY PRODUCE ISOLD LARGE HAIL FROM THE TX
S PLAINS INTO THE TRANS-PECOS REGION OF SW TX.

[Thunder]

Hi, I have a question and I hope you can answer it.

Lets say there is a broad area of strong cap and a storm successfully bust through an area of weaker cap. Does the surrounding strong cap prevent the storm, or at least slow the movement, from doing much? Like for an example, a ship trying to sail thru thick ice in ocean and sometime getting stuck. Is it that way with the storms? Do they have to struggle moving thru the strong cap or it doesn't matter once they bust an area?