Plains tornado threat Mon 5/27-Fri 5/31

[Srain]

 

[OUGrad05]

The latest from SPC:

 

 

 

 DAY 1 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0728 AM CDT WED MAY 29 2013

   VALID 291300Z - 301200Z

   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF THE ERN TX
   PANHANDLE...NW TX...WRN TO CNTRL OK AND WRN TO CNTRL KS...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE GREAT
   PLAINS...MID-MO VALLEY AND MID TO UPPER MS VALLEY...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE ERN GREAT
   LAKES REGION...NRN APPALACHIAN MTNS AND WRN TO SRN NEW ENGLAND...

   ...WIDESPREAD SEVERE WEATHER WITH TORNADOES LIKELY THIS AFTERNOON
   AND EVENING ACROSS PARTS OF THE SRN AND CNTRL PLAINS

   ...SRN AND CNTRL PLAINS...
   A NEGATIVELY-TILTED UPPER-LEVEL TROUGH EXTENDING FROM THE FOUR
   CORNERS SWD INTO NRN MEXICO WILL MOVE EWD INTO THE CNTRL AND SRN
   HIGH PLAINS TODAY. AT THE SFC...A LOW WILL GRADUALLY DEEPEN ACROSS
   THE CNTRL HIGH PLAINS AS A DRYLINE SHARPENS THIS AFTERNOON. TO THE
   EAST OF THE DRYLINE ACROSS THE ERN TX PANHANDLE...WRN OK AND
   SOUTHWEST KS...SFC DEWPOINTS SHOULD BE IN THE 65 TO 70 F RANGE
   ALLOWING FOR STRONG DESTABILIZATION BY MIDDAY. THUNDERSTORMS SHOULD
   INITIATE ALONG AND EAST OF THE DRYLINE THIS AFTERNOON BUT THE TIMING
   OF INITIATION IS STILL UNCERTAIN. THE DETERMINISTIC MODELS SUGGEST
   THAT STORMS WILL INITIATE ALONG THE DRYLINE BY 18Z BUT THIS APPEARS
   TO BE TOO EARLY. THE CURRENT THINKING IS THAT CELL INITIATION WILL
   BE DELAYED UNTIL ABOUT 20Z...MORE IN LINE WITH SOME OF THE HI-RES
   GUIDANCE.  AS CELLS INITIATE...THE STRONG INSTABILITY SHOULD ENABLE
   RAPID CELL INTENSIFICATION. DUE TO THE AMOUNT OF INSTABILITY...STEEP
   MID-LEVEL LAPSE RATES AND MODERATE DEEP LAYER SHEAR...A SEVERE
   THREAT SHOULD DEVELOP ACROSS A WIDESPREAD AREA LATE THIS AFTERNOON
   INTO THE EVENING. THE MAGNITUDE OF INSTABILITY AND DEEP LAYER SHEAR
   COMBINED WITH STEEP LAPSE RATES AND STRONG LOW-LEVEL SHEAR WILL MAKE
   A SIGNIFICANT SEVERE EVENT POSSIBLE ACROSS THE MODERATE RISK AREA.

   FORECAST SOUNDINGS AT 21Z FROM DODGE CITY...CHILDRESS AND LAWTON
   SHOW LOADED-GUN SOUNDINGS WITH MLCAPE OF 2000 TO 3500 J/KG...0-6 KM
   SHEAR AROUND 40 KT AND 700 TO 500 MB LAPSE RATES OF 8.0 C/KM. THIS
   IMPRESSIVE ENVIRONMENT SHOULD EASILY SUPPORT SUPERCELL DEVELOPMENT
   AND LARGE HAIL WILL BE LIKELY WITH ANY ROBUST UPDRAFT THAT
   INITIATES. HAILSTONES GREATER THAN 2 INCHES IN DIAMETER WILL BE
   POSSIBLE WITH SUPERCELLS THAT BECOME DOMINANT. TORNADOES WILL ALSO
   BE POSSIBLE WITH THE MORE ORGANIZED SUPERCELLS WITH THE THREAT
   INCREASING LATE THIS AFTERNOON AS STORMS MOVE EWD AWAY FROM THE
   DRYLINE. THE GREATEST POTENTIAL FOR STRONG TORNADOES THIS AFTERNOON
   IS EXPECTED TO DEVELOP FROM NEAR DODGE CITY SWD ACROSS THE ERN TX
   PANHANDLE AND WRN OK TO AROUND CHILDRESS WHERE SFC WINDS ARE LOCALLY
   BACKED. DUE TO IMPRESSIVE SHEAR AND THERMODYNAMICS...A 15 PERCENT
   TORNADO CONTOUR HAS BEEN ADDED FROM SW KS SWD INTO NW TX WHERE
   LOW-LEVEL SHEAR SHOULD BE ENHANCED BY A STRENGTHENING 40 TO 55 KT
   LOW-LEVEL JET EARLY THIS EVENING. SWATHS OF WIND DAMAGE WILL BE
   POSSIBLE WITH THE MORE INTENSE SUPERCELLS AND BOW ECHOS.

   A SEVERE THREAT SHOULD ALSO DEVELOP FROM WRN AND CNTRL NEB SEWD INTO
   NE KS THIS AFTERNOON AND EVENING. HOWEVER...SFC DEWPOINTS SHOULD BE
   LOWER THAN IN AREAS TO THE SOUTH AND THIS COULD KEEP SEVERE THREAT
   COVERAGE SLIGHTLY LESS WIDESPREAD. LARGE HAIL...WIND DAMAGE AND A
   FEW TORNADOES WILL BE POSSIBLE ACROSS NRN PARTS OF THE CNTRL PLAINS.


   ...NRN PLAINS/UPPER MS VALLEY...
   SOUTH TO SOUTHWEST FLOW WILL BE IN PLACE ACROSS THE NRN PLAINS AND
   UPPER MS VALLEY TODAY AS A NEGATIVELY-TILTED UPPER-LEVEL TROUGH
   MOVES EWD INTO THE CNTRL HIGH PLAINS. MODEL FORECASTS DEVELOP AN
   AXIS OF MODERATE INSTABILITY FROM NE NEB EXTENDING NWD ACROSS ECNTRL
   SD INTO SE ND WHERE SFC DEWPOINTS SHOULD BE IN THE 55 TO 60 F RANGE.
   A CAPPING INVERSION SHOULD WEAKEN QUICKLY BY MIDDAY ALLOWING FOR
   SCATTERED CONVECTIVE INITIATION ALONG AND SOUTH OF A WARM FRONT FROM
   ERN SD EWD ACROSS SRN MN INTO SCNTRL WI. THUNDERSTORMS SHOULD ALSO
   INITIATE FURTHER WEST NEAR THE NOSE OF THE LOW-LEVEL JET AND IN WRN
   NEB AND WRN SD ALONG THE WRN EDGE OF MODERATE INSTABILITY. DUE TO
   THE MODERATELY UNSTABLE AIRMASS ACROSS MUCH OF THE NRN PLAINS AND
   UPPER MS VALLEY...A SEVERE THREAT IS FORECAST FOR A BROAD AREA.

   FORECAST SOUNDINGS AT NORFOLK NEB...ABERDEEN SD AND SOUTH OF
   LACROSSE WI GENERALLY SHOW SBCAPE VALUES REACHING THE 1500 TO 2500
   J/KG RANGE BY LATE THIS AFTERNOON. THIS COMBINED WITH 35 TO 45 KT OF
   DEEP LAYER SHEAR SHOULD BE FAVORABLE FOR SEVERE THUNDERSTORM
   DEVELOPMENT WITH SUPERCELLS POSSIBLE ESPECIALLY WHERE
   DESTABILIZATION MAXIMIZES. SUPERCELLS SHOULD HAVE A THREAT FOR LARGE
   HAIL WITH THE GREATEST POTENTIAL OVER SRN SECTIONS OF THE NRN PLAINS
   WHERE MID-LEVEL LAPSE RATES ARE FORECAST TO BE STEEP AND TEMPS ALOFT
   WILL BE COLD ASSOCIATED WITH THE APPROACHING UPPER-LEVEL TROUGH. A
   WIND DAMAGE THREAT WILL ALSO BE LIKELY WITH ANY ORGANIZED
   LINE-SEGMENT THAT CAN PERSIST INTO THE EARLY EVENING WHEN THE
   LOW-LEVEL JET IS FORECAST TO MARKEDLY STRENGTHEN. INCREASING
   LOW-LEVEL SHEAR DURING THE EARLY EVENING WILL ALSO MAKE TORNADOES
   POSSIBLE WITH SUPERCELLS AND BOWING LINE-SEGMENTS.

   ...GREAT LAKES...
   SOUTH TO SOUTHWEST FLOW WILL BE IN PLACE ACROSS THE LOWER OH VALLEY
   WITH AN UPPER-LEVEL RIDGE LOCATED IN THE GREAT LAKES REGION. AT THE
   SFC...SOUTH TO SWLY FLOW WILL EXIST FROM THE OH VALLEY NWD INTO
   LOWER MI WHERE SFC DEWPOINTS SHOULD BE IN THE LOWER TO MID 60S F
   ALLOWING FOR MODERATE DESTABILIZATION BY THIS AFTERNOON. IN SPITE OF
   LIMITED LARGE-SCALE ASCENT...THUNDERSTORM DEVELOPMENT MAY OCCUR LATE
   THIS MORNING OR EARLY THIS AFTERNOON WHERE GAPS IN THE CLOUD COVER
   ALLOW FOR STRONGER SFC HEATING. THE MODELS SUGGEST THAT THE GREATEST
   POTENTIAL FOR THUNDERSTORM DEVELOPMENT WILL EXIST FROM NRN IL EWD
   ACROSS NRN IND...NRN OH AND SRN LOWER MI. A MARGINAL WIND DAMAGE
   THREAT WILL BE POSSIBLE WITH STORMS THAT CAN DEVELOP IN AREAS THAT
   DESTABILIZE THE MOST AND WHERE LOW-LEVEL LAPSE RATES BECOME
   STEEPEST.

   ...LOWER GREAT LAKES/NEW ENGLAND...
   AN UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS THE LOWER GREAT LAKES
   REGION INTO NEW ENGLAND TODAY. AT THE SFC...A MOIST AXIS SHOULD BE
   IN PLACE FROM THE MID-ATLANTIC EXTENDING NNWWD INTO CNTRL NY ALONG
   WHICH MODERATE INSTABILITY MAY DEVELOP BY AFTERNOON.  MODEL
   FORECASTS SUGGEST STORMS WILL INITIATE ALONG THE INSTABILITY
   GRADIENT FROM LAKE ERIE ENEWD INTO UPSTATE NEW YORK NEAR THE AXIS OF
   A 30 TO 40 KT LOW-LEVEL JET. AS THUNDERSTORMS EXPAND IN COVERAGE AND
   MOVE ESEWD INTO NE PA...THE HUDSON RIVER VALLEY AND WRN NEW ENGLAND
   A SEVERE THREAT WILL BE POSSIBLE DURING THE MID TO LATE AFTERNOON.

   FORECAST SOUNDINGS LATE THIS AFTERNOON AT ALBANY NY...SCRANTON PA
   AND SPRINGFIELD MA GENERALLY SHOW MLCAPE VALUES IN THE 1000 TO 1500
   J/KG RANGE WITH 30 TO 40 KT OF DEEP LAYER SHEAR. THIS COMBINED WITH
   STEEP LOW-LEVEL LAPSE RATES AND UNIDIRECTIONAL WIND PROFILES ABOVE
   THE BOUNDARY LAYER SHOULD BE FAVORABLE FOR SEVERE MULTICELL
   LINE-SEGMENTS WITH WIND DAMAGE POTENTIAL. A SUPERCELL THREAT WILL
   ALSO BE POSSIBLE WHERE THE STRONGEST SFC HEATING OCCURS. IF
   SUPERCELLS CAN DEVELOP...THEN AN ISOLATED THREAT FOR TORNADOES AND
   HAIL WILL BE POSSIBLE LATE THIS AFTERNOON.

 

 

The wording in particular regarding the area S. of Dodge and down to the Red River (ie the 15% hatched area) makes me think they are now expecting the possibility of numerous tornadoes.  While they didn't ellude to upgrading to high risk, I am now beginning to wonder if they wont consider that at 11:30 or perhaps early afternoon.  I'm also becomining increasingly worried about the OKC metro, should a tail end charlie pop up between Lawton and Chickasaw later this evening and track up the I44 corridor.  Conditions would be favorable for a continued tornado threat into the evening hours.

[Ian]

Marks vid from yday note the hail hitting (sound) right by us early.

[Ground Scouring]

The latest from SPC:

The wording in particular regarding the area S. of Dodge and down to the Red River (ie the 15% hatched area) makes me think they are now expecting the possibility of numerous tornadoes.  While they didn't allude to upgrading to high risk, I am now beginning to wonder if they wont consider that at 11:30 or perhaps early afternoon.

The 15% hatched TOR probabilities, and especially the 30% wind probabilities, would need to be both larger and higher to warrant a High Risk. You would probably need 45% hatched TOR and 45% wind to, perhaps, gain a High Risk. I do not see anything in the modeling or the environment that would justify such drastic change.

 

We have this rather-tiring discussion, often with veiled criticism of the SPC, before every near-significant event. Usually the SPC, in the end, does extremely well.

 

Edit: On the other hand, the rather persistent low-level backing of the winds over much of W OK after 00Z is disconcerting and does hint at a robust tornado threat. The WRF-NMM shows tornadic supercells until after 09Z in W-C KS and OK...

 

One of the top CIPS analogs, 06/01/1990, featured a large F4 tornado near Iraan, TX.

[dljuly3]

The 15% hatched TOR probabilities, and especially the 30% wind probabilities, would need to be both larger and higher to warrant a High Risk. You would probably need 45% hatched TOR and 45% wind to, perhaps, gain a High Risk. I do not see anything in the modeling or the environment that would justify such drastic change.

 

We have this rather-tiring discussion, often with veiled criticism of the SPC, before every near-significant event. Usually the SPC, in the end, does extremely well.

 

Edit: On the other hand, the rather persistent low-level backing of the winds over much of W OK after 00Z is disconcerting and does hint at a robust tornado threat. The WRF-NMM shows tornadic supercells until after 09Z in W-C KS and OK...

 

From the SPC webpage. Don't see us hitting 30% tor today and the winds definitely aren't going to make it to a 60% hatch. So I'd also be shocked to see any upgrade to high risk.

[Ground Scouring]

GFS forecast sounding for 00Z Thursday, west of Woodward, OK:

 

 

Similar sounding profiles occur at 00Z north through Meade, DDC, and Grainfield, KS.

[scoresman]

SW OK looks prime if you ask me. If I could chase that would be my target.

[OUGrad05]

From the SPC webpage. Don't see us hitting 30% tor today and the winds definitely aren't going to make it to a 60% hatch. So I'd also be shocked to see any upgrade to high risk.

Didn't realize the next bump up was 30%...I don't see that today...

 

And snowflake, I'm not criticizing SPC at all.  They've done fantastically well this year and have a lot of faith, especially their track record this year...that was also a good point regarding coverage and possible high risk.  Probably not in the cards given the probs table above and the narrow corridor of greatest instability.  Although I wouldn't be surprised to see the 15% area moved to the east another 30 to 40 miles.

[Ed Lizard]

Marks vid from yday note the hail hitting (sound) right by us early.

 

Who yelped in pain?

[Brick Tamland]

Hope everyone in the plains is safe today. It's been a rough two weeks out there.

[HM]

The 15% hatched TOR probabilities, and especially the 30% wind probabilities, would need to be both larger and higher to warrant a High Risk. You would probably need 45% hatched TOR and 45% wind to, perhaps, gain a High Risk. I do not see anything in the modeling or the environment that would justify such drastic change.

 

We have this rather-tiring discussion, often with veiled criticism of the SPC, before every near-significant event. Usually the SPC, in the end, does extremely well.

 

Edit: On the other hand, the rather persistent low-level backing of the winds over much of W OK after 00Z is disconcerting and does hint at a robust tornado threat. The WRF-NMM shows tornadic supercells until after 09Z in W-C KS and OK...

 

One of the top CIPS analogs, 06/01/1990, featured a large F4 tornado near Iraan, TX.

 

This year continues to show up again and again. I'm hoping for the best here; it looks pretty bad.

[Brick Tamland]

This year continues to show up again and again. I'm hoping for the best here; it looks pretty bad.

 

How does the threat today compare to the day of the Moore, OK tornado last week?

[HM]

How does the threat today compare to the day of the Moore, OK tornado last week?

 

The Moore, OK day featured a dryline bulge with locally enhanced backed surface winds. The jet aloft was more zonal, leading to classic hodographs and excellent directional shear. I think Sam posted it in the other thread that the EHI to 3km spiked well over 10 in the bulge area near Moore. Today is a deeper cyclone with stronger winds under an unseasonably strong trough for the end of May. The dryline will be well west of the area. Keep an eye on these dryline bulges / surface obs/mesonets etc. Tomorrow looks more like last weekend's setup than today.

[Dsnowx53]

Just a few quick pictures from the CO/NE storms.

Those are gorgeous! Nice job.

[Dsnowx53]

Added a little more contrast, but here is my best photo of the tornado near Salina. Absolutely incredible.

IMG_3896_3.jpg

Nice! Here's a shot I got early on as the tornado first developed near Bennington, KS.

Nice! We didn't get there early enough to be outside for the cone part...we saw the cone when we were in the car repositioning. Then when we got out, it was a lot more "wedgy".

[Ground Scouring]

I know that the 12Z run is not online yet, but does anyone have access to the initial release of the 12Z WRF-NMM? If so, may you please give a preview for those of us who lack such access?

[jojo762]

13Z HRRR looks like garbage for a widespread Tornado threat, besides when CI takes place, when things are still discrete things look excellent. But it rapidly goes linear from SW Nebraska to NW Oklahoma. Looks like a good Squall line though, however it does appear that there would be good potential for a few discrete Supercells to go in W-Central/ SW Oklahoma, since it doesn't back build the line that far south. Haven't looked at WRF yet, which apparently looks pretty good, but the HRRR look like conplete garbage IMO.

[Chinook]

The 4km NAM shows a quick transition to a long squall line at 21z. It seems that a 15% risk for tornadoes wouldn't verify if this happens.

 

http://www.meteo.psu.edu/~fxg1/NAMSFC4SC_12z/rad9.html

[David Reimer]

The 4-KM NAM develops everything east of the 15% tornado this afternoon with development towards the west around 0Z. Weird run...

[Dsnowx53]

Our preliminary target is Elk City, though that could change upon our lunch evaluation.

[Ground Scouring]

The 4km NAM shows a quick transition to a long squall line at 21z. It seems that a 15% risk for tornadoes wouldn't verify if this happens.

 

http://www.meteo.psu.edu/~fxg1/NAMSFC4SC_12z/rad9.html

Both the NAM and the RUC-HRRR show almost no low-level backing of the winds over W-C KS / OK. Once again they differ greatly from the 12Z GFS and probably the 12Z WRF-NMM. I tend to give more synoptic weight to the latter as the NAM and the RUC-HRRR have not always performed well in this pattern. Interestingly, the SPC's wording this morning seemed to reflect the GFS and the WRF-NMM more than the NAM or the RUC-HRRR.

[tornadoguy11]

I'm sitting in Erick, OK for the mean time, I like my chances for West central OK or maybe sliding down south to SW OK

[tornadotony]

I would favor as far south as possible today given the propensity for veer-back-veer profiles with latitude.

[OUGrad05]

Both the NAM and the RUC-HRRR show almost no low-level backing of the winds over W-C KS / OK. Once again they differ greatly from the 12Z GFS and probably the 12Z WRF-NMM. I tend to give more synoptic weight to the latter as the NAM and the RUC-HRRR have not always performed well in this pattern. Interestingly, the SPC's wording this morning seemed to reflect the GFS and the WRF-NMM more than the NAM or the RUC-HRRR.

I agree looking at how models have handled similar scenarios in hte past is important.  I also like to see if initialization was wrong/screwy because that can also play a crucial role in how these scenarios are unfold on the models.  If the NAM initialized poorly you could probably take the result with a grain of salt.  When they all initialize well and have divergent outputs the day of, you divert to your suggestion and generally relying on the data from the historically more accurate model...

 

SPC has been on fire this year with forecasting so I'm interested to see the 11:30 update. 

[SmokeEater]

Tor probs downgraded back to 10% in the 11:30 outlook.

[yoda]

Tor probs downgraded back to 10% in the 11:30 outlook.

 

Along with MOD risk being moved up into NE due to hail

[Ian]

Meso up already for the southern area

[Jim Marusak]

storm vectors are suggesting ~ 210/220, as per the latest models, and what's being seen on the radar attm. that should change for KS/TX/NE over to like 250/260 in the late evening/overnight as the frontal/dry-line band comes through later on.

[Ground Scouring]

The 12Z WRF-NMM shows a rather widespread tornado outbreak between 20Z-03Z tonight across much of OK and KS...maybe this event, though not warranting a High Risk, will hit the 15% TOR criteria and perhaps up to 30% TOR in part of the warm sector.

 

0100Z tonight:

 

[yoda]

http://www.spc.noaa.gov/products/watch/ww0239.html

Probs 70/50 for TOR

DISCUSSION...TSTM INITIATION IS UNDERWAY E OF THE DRYLINE IN

RESPONSE TO THE EWD MIGRATION OF A SHORT-WAVE TROUGH INTO THE SRN

PLAINS. THE PRESENCE OF VERY STEEP MIDLEVEL LAPSE RATES AND A MOIST

BOUNDARY LAYER IS ALREADY RESULTING IN MLCAPE VALUES OF 2000-3000

J/KG WITH A DECREASING CAP. DESPITE SOME VEER-BACK TENDENCIES IN

OBSERVED AND FORECAST WIND PROFILES...LOW-LEVEL SHEAR WILL

STRENGTHEN INTO THIS EVENING SUPPORTING A RISK FOR TORNADOES /SOME

POTENTIALLY SIGNIFICANT/ IN ADDITION TO VERY LARGE HAIL WITH THE

MOST INTENSE SUPERCELLS THAT DEVELOP.