May '10 Weather Discussion

[Thunder]

David, just a request. Don't update the graphics in place of the old. It's all saved to see the progress, would prefer posting the new graphic with the old intact, so we can compare the changes along the way.

[scootweather]

SPC isn't picking up on the 2nd L forming to our southwest?

That isn't a low forming down there, that is an remnant one.

[venture]

David, just a request. Don't update the graphics in place of the old. It's all saved to see the progress, would prefer posting the new graphic with the old intact, so we can compare the changes along the way.

Yeah I just thought about that today.

Will change the naming process.

[venture]

New 00Z NAM blows up convection all along the dryline now.

Will adjust outlook when GFS roles. If they agree...will extend Moderate further south. Also if they agree, expect SPC to role with a Day 2 Moderate hatched area for most of Oklahoma.

http://www.twisterdata.com/data/mode...PCPIN_3_HR.png

[venture]

Updated outlook based on tonights models. I scaled down Kansas a bit as models really backed off up there. More so due to the situation of precip on going during Monday morning. More in a bit.

[venture]

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1236 AM CDT SUN MAY 09 2010

VALID 101200Z - 111200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS NCNTRL/NE OK...SCNTRL/SE KS AND EXTREME SW MO...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL/SRN PLAINS TO THE MID-MS VLY...

***SUPERCELLS WITH LONG-TRACK STRONG TORNADOES AND VERY LARGE HAIL EXPECTED MONDAY LATE AFTN/EVENING ACROSS PARTS OF CNTRL/N OK...SE KS AND SW MO***

...CNTRL/SRN PLAINS TO THE MID-MS VLY...
WATER VAPOR SHOWS A HEALTHY MID-LVL SHORTWAVE TROUGH APPROACHING THE CNTRL/NRN CA COAST SUNDAY MORNING. FEATURE WILL REACH THE FOUR-CORNERS REGION MONDAY MORNING AND THE CNTRL/SRN PLAINS BY EVENING. SFC LOW WILL INTENSIFY OVER SCNTRL KS MONDAY AFTN BEFORE TRANSLATING TO N MO BY 12Z TUESDAY. TO THE S OF THE LOW...A DRYLINE WILL MIX EWD INTO SCNTRL KS AND WRN PARTS OF TX/OK DURING THE AFTN AND BE THE IMPETUS FOR TSTM INITIATION.

THERE STILL REMAINS A SLIGHT AMOUNT OF UNCERTAINTY WITH RESPECT TO TROUGH TIMING/SFC FEATURE PLACEMENT AND GFS REMAINS ON THE ERN EDGE OF THE ENVELOPE OF SOLUTIONS. CANNOT DISCOUNT THAT IDEA COMPLETELY GIVEN HOW MOBILE/ZONAL THE FLOW REGIME WILL BECOME IN THE NEXT 24-48 HOURS AND CURRENT DAY 2 OTLK WILL INCLUDE ELEMENTS OF BOTH 00Z NAM/GFS...MOST LIKE THE 12Z ECMWF.

ELEVATED CONVECTION...WHICH MAY ALREADY BE PRODUCING LARGE HAIL ACROSS PORTIONS OF OK AND ERN KS MONDAY MORNING...SHOULD MOVE ENE TOWARD THE MID-MS VLY DURING THE AFTN. AIR MASS SHOULD RECOVER RAPIDLY IN WAKE OF THESE STORMS WITH MONDAY AFTN MID-60S SFC DEW POINTS SURGING NWD THROUGH OK AND INTO SCNTRL KS. CINH...RATHER STRONG INITIALLY...SHOULD WEAKEN WITH THE APPROACH OF DCVA... DEEPENING DRYLINE CIRCULATION AND STRONG HEATING. TSTM INITIATION WILL OCCUR MID-LATE AFTN...MOST LIKELY IN SCNTRL KS AND NCNTRL OK...WITH MORE ISOLD STORMS FARTHER S ALONG THE LENGTH OF THE DRYLINE INTO SWRN OK AND W TX.

AS STORMS MOVE OUT OF THE DRYLINE CIRCULATION...LARGELY PERPENDICULAR DEEP-LAYER WIND VECTORS...MLCAPES TO 3000 J/KG AND EFFECTIVE SHEAR 50-70 KTS WILL FAVOR DISCRETE SUPERCELLS WITH VERY LARGE HAIL. FCST HODOGRAPHS EXHIBIT VERY STRONG LOW-LEVEL SRH IN EXCESS OF 400 M2/S2 AND GIVEN ANTICIPATED STORM MODE...INCREASE IN THE NOCTURNAL EVENING LLJ AND LOWERING LCL/S...LONG-TRACK STRONG TORNADOES WILL BE POSSIBLE... PARTICULARLY FROM OK PORTION OF I-40/44 NWD INTO SCNTRL/SERN KS DURING THE EARLY EVENING.

WARM SECTOR WILL RAPIDLY RECOVER DOWNSTREAM OF EARLY EVENING ACTIVITY INTO SWRN MO AND SET-UP APPEARS CONDUCIVE TO SUPPORT DISCRETE SUPERCELLS WELL INTO THE EVENING. EVENTUALLY...ACTIVITY WILL TRANSITION INTO LINES/CLUSTERS OVERNIGHT WITH DMGG WINDS...ISOLD TORNADOES AND LARGE HAIL PROBABILITIES AS FAR E AS THE MID-MS RVR VLY BY 12Z TUESDAY.

FARTHER S...SUPERCELLS THAT MAY FORM ACROSS SW OK INTO W TX WILL DIMINISH DURING THE EARLY EVENING AS STRONGER FORCING EXITS TO THE N OF THE REGION.

..RACY.. 05/09/2010

[oknacreous]

The 12Z NAM model is extremely ominous for central and north-central Oklahoma Monday evening, provided that a storm can develop and move into the forecast environment of high humidity, strong instability and extreme low-level wind shear. Still a chance that won't happen, but people should really be aware of the weather starting 3pm tomorrow into the evening. Storms will be moving toward the ENE very fast - 55 mph - so a hypothetical tornado over Union City would move to downtown OKC in less than 30 minutes.

[venture]

Agree. Not going to be changing the risk graphic at all for now. One modification would be to paint more of KS back into the moderate area. I think SPC will move the MDT further SW a bit. The best dynamics appear as they will be in NC OK into KS. The best instability (with still very good dynamics) will be in Central OK.

Someone on ST summed it up best. There are two areas in play. KS closer to the low where we may see a higher number of tornadoes produces from a classic tornado machine setup. However, in OK there is a great chance that what forms will be 1 or 2 monster supercells that can just churn away with a long track tornado.

Storm motions are still pretty scary with stuff screaming east at 40-50 mph.

[venture]

As expected, the MDT was expanded south a bit and also more to the north. It now includes nearly all of the Metro area except for the far western portions.





DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1235 PM CDT SUN MAY 09 2010

VALID 101200Z - 111200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF KS/OK TO SOUTHWEST MO...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL/SOUTHERN PLAINS TO MIDDLE MS RIVER VALLEY...

...SUPERCELLS WITH STRONG TORNADOES AND VERY LARGE HAIL ARE EXPECTED MONDAY LATE AFTERNOON AND EVENING ACROSS PARTS OF OK/KS INTO SOUTHWEST MO...

...CENTRAL/SOUTHERN PLAINS TO MIDWEST/MIDDLE MS RIVER VALLEY...
WITHIN A PROGRESSIVE/RELATIVELY STRONG BELT OF WESTERLIES...A SHORTWAVE TROUGH CURRENTLY ALONG THE NORTHERN CA COAST IS EXPECTED TO ADVANCE EAST-NORTHEASTWARD FROM THE FOUR CORNERS VICINITY TO THE LOWER/MIDDLE MO RIVER VALLEY AND MIDWEST MONDAY/MONDAY NIGHT.

OWING TO A 50+ SOUTHWESTERLY LOW LEVEL JET AND ROBUST ELEVATED MOISTURE TRANSPORT REGIME...EARLY DAY ELEVATED TSTMS...WITH AT LEAST SOME THREAT FOR SEVERE STORMS CAPABLE OF HAIL...WILL LIKELY BE ONGOING MONDAY MORNING ACROSS EASTERN NEB/EASTERN KS/NORTHEAST OK TO ADJACENT PORTIONS OF IA/MO/AR. ON THE EDGE OF AN EASTWARD BUILDING ELEVATED MIXED LAYER...THESE EARLY DAY STORMS COULD CONTINUE TO PRODUCE SEVERE HAIL THROUGH THE MORNING AS THIS ACTIVITY TRANSITIONS EAST-NORTHEASTWARD ACROSS THE REGION.

OTHERWISE...BENEATH THE STRENGTHENING ELEVATED MIXED LAYER...MAINLY MIDDLE 60S F SURFACE DEWPOINTS WILL BECOME WELL ESTABLISHED IN THE PRE-DRYLINE WARM SECTOR FROM PORTIONS OF WEST/NORTH TX INTO OK AND SOUTHERN KS. THERE IS SOME CONCERN THAT EARLY DAY STORMS/CLOUD COVER COULD IMPEDE APPRECIABLE DESTABILIZATION WITH NORTH EXTENT ACROSS KS...BUT SUCH DETAILS WILL BE MORE READILY RESOLVED IN THE DAY 1 TIME FRAME.

OWING TO SHORTWAVE TROUGH ASSOCIATED DVCA AND STRONG HEATING/MIXING IN VICINITY OF THE DRYLINE...THE CAP IS EXPECTED TO GRADUALLY ERODE THROUGH MID/LATE AFTERNOON. CURRENT THINKING IS THAT SURFACE BASED SEVERE TSTM DEVELOPMENT COULD FIRST OCCUR ACROSS WEST CENTRAL KS BY MID AFTERNOON...WITH SUBSEQUENT DEVELOPMENT PROBABLE ALONG THE DRYLINE /AUGMENTED PERHAPS BY EFFECTIVE WARM FRONT INTERSECTION OR EARLY DAY CONVECTIVE OUTFLOW/ FROM SOUTH CENTRAL KS INTO CENTRAL OK BY LATE AFTERNOON/EARLY EVENING.

DRYLINE PERPENDICULAR DEEP LAYER WIND VECTORS...WARM/MOIST SECTOR MLCAPE VALUES OF 2000-3500 J/KG...AND EFFECTIVE SHEAR OF 50-70 KT WILL SUPPORT DISCRETE SUPERCELLS WITH THE POSSIBILITY OF VERY LARGE HAIL. AS LOW LEVEL/NEAR-1 KM FLOW RE-INTENSIFIES DURING THE EARLY EVENING HOURS...FORECAST SOUNDINGS ALSO REFLECT 300-400 M2/S2 OF 0-1 KM/EFFECTIVE SRH AHEAD OF THE DRYLINE...WHICH SUPPORTS THE POSSIBILITY OF SOME STRONG TORNADOES...PARTICULARLY FROM THE OK PORTION OF I-40/44 INTO SOUTH CENTRAL KS EITHER SIDE OF I-35/135.

EVENTUALLY MONDAY NIGHT...ACTIVITY WILL TRANSITION INTO LINES/CLUSTERS WITH DAMAGING WINDS...ISOLATED TORNADOES...AND LARGE HAIL AS FAR EAST AS THE MIDDLE MS RIVER VALLEY BY EARLY TUESDAY.

FARTHER SOUTH...IT SEEMS PROBABLE THAT STORM DEVELOPMENT MAY BE A BIT MORE ISOLATED WITH SOUTH-SOUTHWESTWARD EXTENT ALONG THE DRYLINE FROM SOUTHERN OK TO WEST CENTRAL TX. NONETHELESS...SHEAR/INSTABILITY WILL AT LEAST CONDITIONALLY SUPPORT A RISK OF SUPERCELLS WITH LARGE HAIL AND PERHAPS A TORNADO OR TWO...MAINLY DURING THE LATE AFTERNOON/EARLY EVENING HOURS.

..GUYER.. 05/09/2010

[venture]

I put a lot of emphasis on the key parts of the discussion. Not much to really add to the forecast discussion. We know the atmosphere will be ripe. The two main questions remain to be the CAP strength and the backing of winds (to the S or SE) closer to the surface. Once those two things are answered, and if they can be handled (breaking cap, winds backing) then this will be a very big day. Preparations for knowing on where to go need to be completed today. Advanced warning lead times will not be like they were May 3rd. These storms will be hauling so we aren't going to have the leisure of watching things on the ground for over an hour before they approach any populated areas.

Edit: Zoomed in view with city names for the Day 2 outlook.

[venture]

Strong storm with some hail possible moving into Harmon County in far SW OK.

[Uncle Slayton]

Got the Dodge gassed up in Norman. What are the odds that I'm going to get to drive it into a tornado tomorrow?

[venture]

Going through making some pretty big changed to AnvilCrawlers.com - Weather Forum and Discussion for Oklahoma today to be ready for tomorrow. Have added in live streaming video through USTREAM that will typically broadcast radar and other images that are important.

The Live Blog/Chat is already active and is passing along tweets from the National Weather Service and local County Emergency Management offices.

Today is mostly going to be testing a bunch of stuff out, so if you all drop by and things look out of place, that's why. :-P

[Thunder]

David, I'm curious. Which causes more damage. Both tornadoes having everything the same. One goes way faster than the other. And the greatest damages come from which tornado?

[venture]

David, I'm curious. Which causes more damage. Both tornadoes having everything the same. One goes way faster than the other. And the greatest damages come from which tornado?

So you are talking about two identical tornadoes, going over identical areas...just one moving at like 20 mph and the other at 50?

I am inclined to say the slower one, for this reason. The slower it moves, the more debris it will have in the funnel staying over the same general area longer. A lot of the damage in a tornado isn't so much from the winds, it is all the flying debris in the funnel. A faster moving tornado would typically pull a lot of that debris away from the area so it isn't being recirculated over the same stuff.

This isn't referencing any study or anything, just what I think would commonly happen.

[Thunder]

You're a genius!

[venture]

I wouldn't say that. LOL

[blangtang]

maybe i missed it, thanks for the updates, but what is the ETA on these twister outbreaks, was it tomorrow evening?

also is that vortex research team gonna try to drive into a twister or is that already over...thx, sounds like there won't be much regular tv on tomorrow night!

those slight/moderate colored circles are pretty amazing to me. I didn't realize they could get such a good bulls eye so far out from when the events occur. Crazy Mike was right!

[venture]

Looking at probably 4-7PM initiation time tomorrow. VORTEX2 is on going right now, but I have a feeling they'll be in Kansas...haven't checked their twitter feed yet.

[venture]

Will be running some test video tonight on the USTREAM feed. None of it is live, but some may be familiar.

[venture]

OUN's AFD included this:

WE ALSO CONTINUE TO STEP UP OUR SEVERE WEATHER MESSAGE FOR THE
EVENT ANTICIPATED AHEAD OF THE DRYLINE ON MONDAY. THE SPC MODERATE
RISK AREA DEPICTS THE REGION WHERE OUR CONFIDENCE IS GREATEST THAT
THE CAP WILL BREAK. ANY STORM FORMING FARTHER SOUTH...HOWEVER...
MAY BE EQUALLY AS STRONG. THE TREND IN THE MODELS HAS
BEEN...COMPARED TO PREVIOUS FORECAST CYCLES...TO PRODUCE GREATER
HEIGHT FALLS...LIFT...AND MID LEVEL COOLING...AS WELL AS A LIGHT
QPF SIGNAL...IN THE AREA SOUTH OF THE MODERATE RISK. THIS INDICATES
A LITTLE GREATER CHANCE OF STORMS INITIATING DOWN TO THE LATITUDE
OF THE RED RIVER. WE INCREASED POPS SOMEWHAT FOR MONDAY EVENING TO
REFLECT THIS.

All things considered, I expect us to be under a High Risk tomorrow.

[oknacreous]

My quick take on the 00Z NAM is that the highest threat of tornadoes has shifted a bit east and northeast, to be more centered on Tulsa/Bartlesville/Stillwater/Shawnee. People in the metro should definitely still pay attention to this one, though.

[venture]

00Z GFS seems to be matching up with NAM and speed this thing up. Dryline is into or past the metro by 7PM now.

[venture]

I'm going to hold off on doing anymore outlook graphics and defer back to SPC going through tomorrow. However, if I were to call it right now...going through NAM and GFS...I would definitely push the higher risk area into the area from Ponca down to Shawnee and over to Muskogee (east and north of that line). Both GFS and NAM have this dryline flying in here by 7PM, a couple hours earlier than previous expected. CIN seems to be coming down some ahead of the dryline, but neither model initiates convection until the dryline passes. A lot of dynamics, a ton of sheer, but it does no good if it tears every updraft apart. NSSL models hint at a couple large supercells along the OK/KS border and then once the dryline gets east of the US-75 area...it lights the fuse and away they go.

As stated before, this doesn't mean OKC is out of the risk area. NWS Norman is being very good with their wording that the Slight risk area is just going to see fewer coverage of storms but the intensities of the storms will be pretty uniform - regardless of where you are. If we see something fire along the dryline by 4PM to the west of OKC...we'll definitely need to watch it very closely.

Since a few questions were thrown into the mix tonight, SPC may hold off on going high risk until the morning model runs are done...if they do. I won't be totally shocked to see OKC out of the moderate risk, but we'll still be in a high end slight with hatching for significant weather.

We'll know more here in an hour when they release their thoughts.

[venture]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT MON MAY 10 2010

VALID 101200Z - 111200Z

...THERE IS A HIGH RISK OF SVR TSTMS ACROSS PARTS OF SE KS AND ERN OK...

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF CNTRL AND ERN KS...CNTRL AND ERN OK...WRN MO AND NW AR...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND CNTRL PLAINS...MID-MS VALLEY AND OZARKS...

...REGIONAL TORNADO OUTBREAK AND LONG-TRACK STRONG TO VIOLENT TORNADOES BECOMING LIKELY IN ERN OK AND SE KS FROM LATE THIS AFTERNOON INTO THE EVENING...

...SRN AND CNTRL PLAINS...
RAPID MOISTURE TRANSPORT WILL TAKE PLACE TODAY ACROSS THE SRN PLAINS AS AN IMPRESSIVE NEGATIVELY-TILTED UPPER-LEVEL TROUGH MOVES QUICKLY INTO THE REGION FROM THE WEST. SCATTERED THUNDERSTORMS SHOULD BE ONGOING ON THE NOSE OF A 50 TO 60 KT LOW-LEVEL JET ACROSS ERN KS WITH THIS CONVECTION BEING SHUNTED NNEWD AWAY FROM THE HIGH RISK AREA AROUND MIDDAY. AT THIS TIME...A WELL-DEFINED MOIST AXIS AND DRYLINE WILL RAPIDLY ORGANIZE MOVING ENEWD ACROSS WRN OK THIS AFTERNOON. SFC DEWPOINTS ARE FORECAST TO RAPIDLY INCREASE INTO THE UPPER 60S TO AROUND 70 F ACROSS ECNTRL OK WHERE FORECAST SFC TEMPS SHOULD REACH THE MID TO UPPER 80S F. THIS RESULTS IN A TONGUE OF STRONG INSTABILITY FROM NRN TX EXTENDING NWD INTO NRN OK WITH MLCAPE VALUES IN THE 3000 TO 4000 J/KG RANGE. AS THE UPPER-LEVEL TROUGH APPROACHES THE INSTABILITY AXIS...A 75-90 KT MID-LEVEL JET WILL MOVE EWD ACROSS NRN OK. THIS FEATURE WILL CREATE VERY STRONG DEEP LAYER SHEAR PROFILES WITH 0-6 KM SHEAR VALUES ACROSS THE HIGH RISK AREA REACHING THE 70 TO 80 KT RANGE. THIS COMBINED WITH THE STRONG INSTABILITY SHOULD RESULT IN RAPID SUPERCELL INITIATION AS STORMS GO UP ALONG THE DRYLINE ON THE WRN EDGE OF THE LOW-LEVEL JET LATE THIS AFTERNOON.

THE LOW-LEVEL JET WILL CREATE VERY STRONG LOW-LEVEL SHEAR PROFILES WITH FORECAST SOUNDINGS ACROSS THE HIGH RISK AREA AT 00Z SHOWING 0-3 KM HELICITIES IN THE 450 TO 550 M2/S2 RANGE SUGGESTING THE SHEAR ENVIRONMENT WILL BE VERY FAVORABLE FOR TORNADOES. THE CURRENT THINKING IS THAT SEVERAL SUPERCELLS WILL INITIATE ALONG THE I-35 CORRIDOR FROM WICHITA SWD TO OKLAHOMA CITY WITH THE CELLS BECOMING TORNADIC TRACKING ENEWD ALONG THE I-44 CORRIDOR INTO THE TULSA AREA AND INTO FAR SE KS BY EARLY EVENING. STORM MOTIONS SHOULD BE TO THE EAST NORTHEAST AT 50 KT SUGGESTING THE TORNADOES COULD BE LONG-TRACK WITH STRONG TO VIOLENT TORNADOES CERTAINLY POSSIBLE ACROSS THE HIGH RISK AREA. FORECAST SOUNDINGS SHOW VERY STEEP MID-LEVEL LAPSE RATES WHICH COMBINED WITH THE STRONG VERTICAL SHEAR SHOULD SUPPORT VERY LARGE HAIL WITH SUPERCELLS THAT DEVELOP ALONG THE DRYLINE. THIS THREAT SHOULD EXIST SSWWD INTO NRN AND WCNTRL TX WHERE SUPERCELLS MAY ALSO PRODUCE A FEW TORNADOES.

FURTHER NORTH IN THE CNTRL PLAINS...THUNDERSTORMS SHOULD ALSO INITIATE NORTH OF SFC LOW IN CNTRL AND NRN KS LATE THIS AFTERNOON. FORECAST SOUNDINGS ACROSS NRN KS SHOW STRONG VERTICAL SHEAR PROFILES SUGGESTING SUPERCELL DEVELOPMENT WILL BE POSSIBLE. SUPERCELLS WILL BECOME INCREASINGLY LIKELY AS MODERATE INSTABILITY DEVELOPS ACROSS ERN KS EARLY THIS EVENING. TORNADOES AND VERY LARGE HAIL WILL BE POSSIBLE WITH SUPERCELLS. HOWEVER...A POTENTIAL FOR WIND DAMAGE WILL ALSO BE POSSIBLE ESPECIALLY IF THE STORMS CAN ORGANIZE INTO A BOWING LINE-SEGMENT MOVING INTO WRN MO DURING THE LATE EVENING.

..BROYLES/STOPPKOTTE.. 05/10/2010

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