jpeters3

Meteorologist
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Posts posted by jpeters3


  1. Please do. My point is that Plains tornado events that last into the night are the exception to the rule and not the norm so in most cases posting those 03z amped up soundings will be pointless.

     

    I'm currently doing a study on this, and you are incorrect.  More often than not, tornado events that produce EF-1 or greater tornadoes during the spring last into the night.

     

    Edit: The question of whether chasing is very relevant after 03Z depends on who you are asking ;-)


  2. Using both DP's and ThetaE as markers for where the surface WF could be, i'd say the warm front will end up about 10-20 miles or so north into Nebraska from the border by 00Z. So on that basis, yes many of the best parameters are north of the warm front, but any supercell along and slightly north/south of the WF will pose a significant tornado risk, no matter where exactly it ends up.

     

    I generally agree with this - anywhere near, or slightly south of the boundary (and slightly south of the sounding I posted) is going to be prime.  I do expect that some of the convection the model is blowing up north of this region is going to be elevated though.  Might end up being elevated supercells with the very high low-level SRH, but elevated none the less.


  3. To me, that just looks like a sounding where shallow convection is occurring in the model. There's also no inversion nor any real SBCINH. I don't think it's north of the WF, although it's basically right on it. The temperatures on the north side of the boundary don't become chilly too quickly, so I can see storms having strong tornado potential right as they cross it.

     

    Shallow convection/clouds or warm front are sort of semantics.  Shallow convection/clouds is common just north of a warm front. Regardless of what is causing the profile to look like this, the shallow statically stable layer shows up in pretty much every profile north of the KS/NE boarder, and has in several rounds of model runs.  What the model shows as SBCIN is not based on the actual surface virtual temperature (you see, the lifted parcel path starts to the right of the surface virtual temperature in the sounding), so the actual SBCIN is probably higher than what is listed on there. You can easily get supercells within an environment like this, but it is very difficult to develop a tornado when surface parcels are convectively inhibited.


  4. FWIW, despite that most of them over-convect, by a lot,  the WRF-NMMB, WRF-ARW, and WRF-NSSL all show impressive UH-tracks basically with any storm that develops from SE/SC NE southward into the C OK. Like I said yesterday, there will be a certain amount of time, probably from 22/23Z to roughly 03Z where the wind-profile will be sufficient, and not wacky enough, combined with the strong/extreme instability where any storm will be capable of producing high-end tornadoes. 4 or 5 hours of potentially numerous intense discrete supercells across the dryline and warm-front is enough for me. 

     

    I am still convinced that most of the profiles in southern NE are actually slightly north of the surface front, and any supercells that develop there will end up being elevated.  Take a look at some profiles out of the high sigtor regions in S nebraska.  They all look like this:

     

    http://climate.cod.edu/hanis/model/fsound/index.php?type=12|NAM|US|con|stp|36|*129,113*|ml|severe

     

    Shallow saturated stable layer.


  5. After looking at the 12Z NAM, I've got my eyes on the KS/NE boarder somewhere between Belleville and Phillipsburg KS.  While the NAM goes crazy with sigtor in southern Nebraska, soundings from this area all show a shallow and very moist inversion, suggesting to me that they are north of the effective surface front and that surface parcels in this area will be somewhat convectively inhibited.  I like the profiles I see in northern KS around 00Z.

     


  6. The SPC didn't make any mention of VBV at all. Strange, I doubt they are dismissing it all together. And if it verifies there's no chance of a high risk, and issuing one would be a mistake on their part, at least in my eyes.

     

    With all the focus on VBV here, I can't seem to find any peer reviewed articles that demonstrate its effect on supercell dynamics.  Can someone point me to an article that addresses VBV?

    From what I gather from rather "hand-wavy" arguments, VBV implies that a supercell ingests the opposite sign of vorticity from its ambient environment at mid levels, which is detrimental to mesocyclone.  The problem I have with this argument is that the primary "fuel source," or the effective inflow layer to a supercell is usually well below the layer where the back-veer portion of the profile is.  So I'm not entirely convinced that the storm is ingesting the opposite-signed ambient horizontal vorticity at mid levels.

    I could be convinced that the changes to the storm-relative wind profile implied by VBV results in more precip falling within the storm's inflow region, and thus evaporative cooling contaminating the storms inflow and leading to outflow dominated storm modes.

    Any thoughts?  I spend most of my time reading MCS papers, so I could have missed some recent articles that address this.


  7. I was simply correcting your poorly worded conjecture. Perhaps you should use the scientific method and try to prove why your hypothesis is false.

     

    You have me on this one.  I should have stated 'To the best of our knowledge, Hurricane Patricia is the strongest tropical cyclone in the history of reliable observations'.

     

    My apologies for harping on you, and then turning around and making a statement like that.


  8.  

    The assertions in this article are still speculative.  You earlier saw with this storm how significantly ADT numbers can sometimes give poor estimations for observed winds.  In this case, the observed winds were higher than ADT estimates; however, there is certainly an error margin on ADT, and 'concluding' that unobserved storms that had ADT numbers a few decimal points higher simply isn't good science.


  9. Hurricane Patricia is the strongest tropical cyclone measured 1-min sustained winds by aircraft reconnaissance in the recorded meteorological history. Pacific typhoon wind speed is generally satellite measured. I would venture to conclude several Pacific typhoons would have as fast or faster 1-min sustained winds using the same metric.

     

    I wouldn't venture to conclude anything from unsubstantiated speculation.

     

    Also, the Dvorak estimates for this system were comparable to, or higher than any other numbers I am familiar with.  Does anyone recall what the highest observed Dvorak numbers are?


  10. Hurricane patricia IS the strongest tropical cyclone in history in terms of 1-min sustained winds.  End of story. 

     

    There is no 'sensationalizing' a TC that achieves a low central pressure of <=880 hPa and 200 mph 1 minute sustained winds for > 6 hours.  This has never happened since reliable measurements have been taken.  Don't try and under sensationalize this event.


  11. The 0Z GFS seems to have initialized with a pressure of around 989 MB. I wouldn't trust much of anything the 0Z run of the GFS says. You put bad data into the run you're going to get bad data out of the run. Basic forecasting 101 when it comes down to utilizing model data. FWIW the high-res GFS had the pressure around 965 MB for initialization. 

     

    gfs_mslp_uv850_east3_2.png

     

    I rarely see the GFS initialize with the correct pressure (presumably due to resolution issues).  Furthermore, a significant component of storm track and intensity is dictated by large scales... so don't throw in the towel on every run that doesn't get the exact pressure right.


  12. Are helicities expected to increase as they move south? Currently the atmosphere doesn't seem to have much spin in that region

     

    Even if you combine modest helicity with massive w gradients in the vertical (with this much cape, your updrafts are going to be very strong), you'll get spin.


  13. HRRR and other hi-res models struggle with subtle set-ups. Hey it's job security for operational mets! Seriously those models are optimized for traditional or classic severe weather sequences. If sensitivity were turned up for subtle events, every traditional outbreak would look like April 27, 2011. Fortunately those are only once a generation in real life. It is not really sensitivity, but the equations and physics required to do well with traditional sequences. Usually it is a trade-off in NWP, unless we have a whole other model for subtle events. With scarce resources, the community favors models that do well in traditional sequences. I'm not complaining about budgets; I mean the scarce resources from Econ 101. The most lives are saved and commerce protected with models that do well in traditional sequences or classic outbreaks.

     

    Even the HRRR did not totally blow it in Kansas IMHO. Despite off the charts TOR parameters, it never showed spectacular mesos in Kansas or Nebraska. 2-5km updraft helicity (weather.cod.edu) was not spectacular. You could get at that on the hi-res NAM indirectly with 925 mb, and the NAM showed uninspiring storm inflow (and some bad outflow NE). While both had gorgeous reflectivity simulations, neither had impressive mesos. They actually did OK in Kansas. On the other hand both missed the incredible tornado show in Colorado. Apparently some human forecasters decided 2000 CAPE, vs 1000 day prior, would do the trick.

     

    Congratulations to all who documented the Colorado storm! Appears it will go down as a Rozel 13 or Haper 04 type career event for you all. Event had 4+ cycles, all photogenic, including a double tornado. Tough to beat that. James Smart shot may become a classic anti-cyclonic tornado photo. Nice work to all who got those!

     

    It's not that the models are "tuned" incorrectly for these marginal events.  The same dynamics and physics that govern marginal events govern outbreak events.  Rather, the events are frequently sensitive to the the upscale influence of prior convection.  For instance, the location of cold pools and their boundaries - meso-delta scale atmospheric circulations that contribute to convective initiation.  These area all processes that are poorly emulated by, and initialized in models.

     

    Outbreak events, on the other hand, are more synoptically driven, and models are better at getting a good handle on the synoptic scale environment. 

     

    The point being - there isn't an easy way to just "tune" the models to better understand these upscale convective feedbacks and nuances of convective initiation.  These processes are inherently chaotic.


  14. Elmer - Tipton tornado assigned preliminary EF-2 rating

     

    elmertiptontrack.jpg

     

     

    000
    NOUS44 KOUN 180234
    PNSOUN
    OKZ006-011-021-023-030-035>038-044-TXZ085-181445-

    PUBLIC INFORMATION STATEMENT
    NATIONAL WEATHER SERVICE NORMAN OK
    934 PM CDT SUN MAY 17 2015

    ...NWS DAMAGE SURVEY FOR 5/16/15 TORNADO EVENT

    .ELMER-ODELL-TIPTON-SNYDER TORNADO...

    RATING:                 EF-2
    ESTIMATED PEAK WIND:    125 MPH
    PATH LENGTH /STATUTE/:  35 MILES
    PATH WIDTH /MAXIMUM/:   TO BE DETERMINED
    FATALITIES:             0
    INJURIES:               0 KNOWN

    START DATE:             MAY 16 2015
    START TIME:             APPROX 535 PM CDT
    START LOCATION:         6 SW ELMER / JACKSON COUNTY / OK
    START LAT/LON:          34.42 / -99.42

    END DATE:               MAY 16 2015
    END TIME:               APPROX 645 PM CDT
    END LOCATION:           APPROX 3 E SNYDER / KIOWA COUNTY / OK
    END LAT/LON:            34.66 / -98.90

    SURVEY_SUMMARY: INFORMATION ABOUT THIS TORNADO IS STILL VERY
    PRELIMINARY. A LARGE MULTIPLE VORTEX TORNADO DEVELOPED IN
    SOUTHERN JACKSON COUNTY OKLAHOMA SOUTHWEST OF ELMER OKLAHOMA AND
    NORTH OF ODELL TEXAS... AND MOVED NORTHEAST THROUGH THE FAR
    NORTHERN PORTION OF WILBARGER COUNTY TEXAS... THEN BACK INTO
    JACKSON COUNTY OKLAHOMA SOUTHEAST OF ELMER. THE TORNADO CONTINUED
    NORTHEAST MOVING THROUGH TILLMAN COUNTY FROM WEST OF TIPTON TO
    SOUTHWEST OF SNYDER... THEN CONTINUED IN KIOWA COUNTY FROM SOUTHWEST
    OF SNYDER TO EAST OF SNYDER. THE DISSIPATION POINT OF THE TORNADO
    HAS NOT BEEN DETERMINED YET. THE MOST INTENSE DAMAGE FOUND SO FAR
    IS CONSISTENT WITH AN EF2 TORNADO.

    .CLEO SPRINGS TORNADO...

    RATING:                 EF-1
    ESTIMATED PEAK WIND:    105 MPH
    PATH LENGTH /STATUTE/:  12 MILES
    PATH WIDTH /MAXIMUM/:   50 YARDS
    FATALITIES:             0
    INJURIES:               0 KNOWN

    START DATE:             MAY 16 2015
    START TIME:             622 PM CDT
    START LOCATION:         5.5 NW FAIRVIEW / MAJOR COUNTY / OK
    START LAT/LON:          36.32 / -98.56

    END DATE:               MAY 16 2015
    END TIME:               642 PM CDT
    END LOCATION:           4 NNE CLEO SPRINGS / MAJOR COUNTY / OK
    END LAT/LON:            36.46 / -98.42

    *SURVEY_SUMMARY: A TORNADO DEVELOPED ABOUT 5.5 MILES NORTHWEST
    OF FAIRVIEW IN MAJOR COUNTY AND MOVED NORTHEAST TO 4 MILES NORTH-
    NORTHEAST OF CLEO SPRINGS JUST EAST OF HIGHWAY 8 AND SOUTH OF THE
    ALFALFA COUNTY LINE. THE TORNADO PASSED ACROSS THE NORTHWEST
    CORNER OF CLEO SPRINGS WITH ADDITIONAL DAMAGE IN CLEO SPRINGS
    CAUSED BY ADJACENT THUNDERSTORM WINDS. THUNDERSTORM WIND DAMAGE
    CONTINUED NORTHEAST FROM WHERE THE TORNADO DISSIPATED TO AREAS
    NEAR AND SOUTHWEST OF HELENA IN ALFALFA COUNTY.

    EF SCALE: THE ENHANCED FUJITA SCALE CLASSIFIES
    TORNADOES INTO THE FOLLOWING CATEGORIES.

    EF0...WEAK......65 TO 85 MPH
    EF1...WEAK......86 TO 110 MPH
    EF2...STRONG....111 TO 135 MPH
    EF3...STRONG....136 TO 165 MPH
    EF4...VIOLENT...166 TO 200 MPH
    EF5...VIOLENT...>200 MPH

    NOTE:
    THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO
    CHANGE PENDING FINAL REVIEW OF THE EVENTS AND PUBLICATION IN
    NWS STORM DATA.
     


  15. I'm not driving anywhere if it is just going to be boring rain or weak thunderstorms. Previously I was thinking of sitting around east of Cheyenne at a gas station on I-80 and looking at the sky. I have cancelled that idea, until further notice.

     

    Note. I am seeing the Denver cyclone set up with a surface circulation north of DIA (Adams/Weld Co). It's all in the 50's with dew points around 48. There's no extremely dry area, as of yet.

     

    With the HRRR hinting at a palmer divide initiation, and the denver cyclone setting up, I may consider driving southeast toward Greeley (or a little bit south) to catch any supercells moving NE off the high terrain.


  16. Really have to wonder about storm initiation today, even near the triple point. Yet another event this season that seemingly had big potential, but became less and less interesting leading up. Making my way up eastern Colorado later today. Those in central/eastern Nebraska may not see much at all, but maybe I'm wrong.

     

    ? There will almost certainly be storm initiation near the triple point (which is right up against the high terrain).  Looks like a pretty decent setup for SE WY / NW NE.

     

    Best way to alleviate questions about convective initiation is to plow convectively unstable flow into mountains


  17. BULLETIN - EAS ACTIVATION REQUESTED  

    TORNADO WARNING  

    NATIONAL WEATHER SERVICE GOODLAND KS  

    1004 PM CDT SAT MAY 9 2015  

     

    THE NATIONAL WEATHER SERVICE IN GOODLAND HAS ISSUED A  

     

    * TORNADO WARNING FOR...  

    NORTHWESTERN SHERIDAN COUNTY IN NORTHWESTERN KANSAS...  

    SOUTHWESTERN DECATUR COUNTY IN NORTHWESTERN KANSAS...  

     

    * UNTIL 1045 PM CDT  

     

    * AT 1004 PM CDT...A CONFIRMED LARGE AND EXTREMELY DANGEROUS TORNADO  

    WAS LOCATED NEAR SELDEN...OR 14 MILES NORTHWEST OF HOXIE...MOVING  

    NORTH AT 25 MPH.  

     

    THIS IS A PARTICULARLY DANGEROUS SITUATION.  

     

    HAZARD...DAMAGING TORNADO.  

     

    SOURCE...WEATHER SPOTTERS CONFIRMED TORNADO.  

     

    IMPACT...YOU ARE IN A LIFE THREATENING SITUATION. FLYING DEBRIS  

    MAY BE DEADLY TO THOSE CAUGHT WITHOUT SHELTER. MOBILE  

    HOMES WILL BE DESTROYED. CONSIDERABLE DAMAGE TO  

    HOMES...BUSINESSES AND VEHICLES IS LIKELY AND COMPLETE  

    DESTRUCTION IS POSSIBLE.  

     

    * LOCATIONS IMPACTED INCLUDE...  

    SELDEN.  

     

    PRECAUTIONARY/PREPAREDNESS ACTIONS...  

     

    TORNADOES ARE EXTREMELY DIFFICULT TO SEE AND CONFIRM AT NIGHT. DO NOT  

    WAIT TO SEE OR HEAR THE TORNADO. TAKE COVER NOW.  

     

    A LARGE AND EXTREMELY DANGEROUS TORNADO IS ON THE GROUND. TAKE  

    IMMEDIATE TORNADO PRECAUTIONS. THIS IS AN EMERGENCY SITUATION.  

     

     

    Okay this is getting ridiculous.  Not much evidence to support an "EXTREMELY DANGEROUS TORNADO".


  18. What's preventing these storms from going down? I saw it said in the warning that there was a Confirmed Tornado, but have yet to see any visuals yet.

     

    I suspect the RFD is a bit cooler than optimal.  There is a pretty well-defined OFB that trails this storm, and supercells that produce well defined cold pools don't usually seem to be prolific tornado producers (again, due to the RFD/cold pool being too cool).  Also, 0-1 km SRH isn't particularly high.

     

    Edit: the storm also appears to be moving just east of the region of highest effective SRH.