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10HPC_2.2_Blair

VIEWS: 15 PAGES: 22

									Convective Initiation and Flow
 Regimes of Severe Storms
Across the Central High Plains



               Scott F. Blair
               National Weather Service
                  Goodland, Kansas
                          Overview
                         Overall Purpose
    Spatial / Temporal Characteristics of Convective Initiation (CI)
      Flow Regime Type Associated With Severe Convection

                          Scope of Study
 Limited to examine severe weather occurring within the GLD CWA
 Determine any signals to better anticipate local severe weather traits




                                                   Goodland County Warning Area
                                                        19 Counties Served
Central High Plains
                                       Central High Plains

Wyoming

           Cheyenne Ridge                Nebraska




                             GLD CWA
             Palmer Divide


Colorado
                                           Kansas



             Raton Ridge



                                         Oklahoma
New Mexico
      Severe Weather Criteria - Defined

      Remained consistent with current warning operations




1” Diameter Hail       50+ Knot Winds            All Tornadoes

            Severe Weather Climatology (1950 – 2006)
        CI / Flow Regime Event Investigations (1997 – 2006)
                Built Upon Defined Criteria
       Severe Weather Climatology
                   1950 – 2006 Severe Reports

                  1950 - 2006 Severe Reports

2500
                                        2504
2000


1500                      1713
                                                        Total
1000


 500       688

   0
                                                Total
        Tornado          Wind           Hail
       Severe Weather Climatology
                   1950 – 2006 Severe Reports

                  1950 - 2006 Severe Reports

2500
                                          2504
2000

                                1713   1923
1500
                                                           MJJ
1000                     1244                              Total

                  688
 500
           565
                                                   Total
   0
                                                 MJJ
        Tornado          Wind          Hail
   Severe Weather Climatology
              1950 – 2006 Severe Reports



                           May, June, and July
                                 82% Tornadoes
                                 77% Hail
                                 73% Wind


76% ALL Severe Weather Occurred May – July

 Climatological Three-Month Maximum of Severe Weather

     Ten-Year Period (1997–2006) Further Examined
Convective Initiation
     First 45 dBZ echo resolved in 0.5 degree
         reflectivity to represent initiation

    Origin of deep moist convection ultimately
      producing 1st severe report in GLD CWA

         Unlimited domain for the origin of
               convective initiation

    New convection (mergers, clusters, outflow)
     associated with original activity NOT used
Convective Initiation
    Spatial Distribution




         285 Event Cases
          May – July (1997-2006)
Convective Initiation
    Spatial Distribution




         285 Event Cases
          May – July (1997-2006)
                                   Convective Initiation
                                                  Temporal Analysis
         80


         70


         60


         50
Events




         40


         30


         20


         10


          0
          00
               00
                    00
                         00
                              00
                                   00
                                        00
                                             00
                                                  00
                                                       00
                                                            00
                                                                 00
                                                                      00
                                                                           00
                                                                                00
                                                                                     00
                                                                                          00
                                                                                               00
                                                                                                    00
                                                                                                         00
                                                                                                              00
                                                                                                                   00
                                                                                                                        00
                                                                                                                             00
         06
              07
                   08
                        09
                             10
                                  11
                                       12
                                            13
                                                 14
                                                      15
                                                           16
                                                                17
                                                                     18
                                                                          19
                                                                               20
                                                                                    21
                                                                                         22
                                                                                              23
                                                                                                   00
                                                                                                        01
                                                                                                             02
                                                                                                                  03
                                                                                                                       04
                                                                                                                            05
                                                                 Time (UTC)                                                 CI

1900 – 2100 UTC Peak Initiation Period (65% Events)
                                            (1900 – 2300 UTC ~85% Events)
                                       Convective Initiation vs. 1st Severe
                                 80                                                                                                                                                                           40

                                 70                                                                                                                                                                           35

                                 60                                                                                                                                                                           30

                                 50                                                                                                                                                                           25
Convective Initiation
                        Events




                                                                                                                                                                                                                   1st Severe Report
                                 40                                                                                                                                                                           20

                                 30                                                                                                                                                                           15

                                 20                                                                                                                                                                           10

                                 10                                                                                                                                                                           5

                                  0                                                                                                                                                                           0
                                      0600
                                             0700
                                                    0800
                                                           0900
                                                                  1000
                                                                         1100
                                                                                1200
                                                                                       1300
                                                                                              1400
                                                                                                     1500
                                                                                                            1600
                                                                                                                   1700
                                                                                                                          1800
                                                                                                                                 1900
                                                                                                                                        2000
                                                                                                                                               2100
                                                                                                                                                      2200
                                                                                                                                                             2300
                                                                                                                                                                    0000
                                                                                                                                                                           0100
                                                                                                                                                                                  0200
                                                                                                                                                                                         0300
                                                                                                                                                                                                0400
                                                                                                                                                                                                       0500
                                                                                                             Time (UTC)
                                             CI                                           Tor                                              Wind                                                 Hail

                         Temporal analysis parsed by CI and 1st severe report / type from event day
                                            Convective Initiation vs. 1st Severe
         80                                                                                                                                                                           40
                                                                                                                                                                                                 Peak CI Period:
                                                                                                                                                                                                1900 UTC – 2100 UTC
         70                                                                                                                                                                           35

         60                                                                                                                                                                           30

         50                                                                                                                                                                           25
                                                                                                                                                                                           Peak 1st Hail Report Period:
Events




         40                                                                                                                                                                           20
                                                                                                                                                                                                2200 UTC – 0000 UTC
         30                                                                                                                                                                           15

         20                                                                                                                                                                           10
                                                                                                                                                                                           Peak 1st Tor Report Period:
         10                                                                                                                                                                           5
                                                                                                                                                                                                2300 UTC – 0000 UTC
          0                                                                                                                                                                           0
              0600
                     0700
                            0800
                                   0900
                                          1000
                                                 1100
                                                        1200
                                                               1300
                                                                      1400
                                                                             1500
                                                                                    1600
                                                                                           1700
                                                                                                  1800
                                                                                                         1900
                                                                                                                2000
                                                                                                                       2100
                                                                                                                              2200
                                                                                                                                     2300
                                                                                                                                            0000
                                                                                                                                                   0100
                                                                                                                                                          0200
                                                                                                                                                                 0300
                                                                                                                                                                        0400
                                                                                                                                                                               0500
                                                                                     Time (UTC)
                                                                                                                                                                                           Peak 1st Wind Report Period:
                     CI                                           Tor                                              Wind                                                 Hail                    2300 UTC – 0100 UTC


                              Large majority of cases exhibit strong diurnal preference
                                   in regards to time of CI and time of 1st resultant severe type

                       Data suggests greatest operational concern with regards to
                                          CI and 1st severe event between 1900 UTC and 0100 UTC
                   500 mb Flow Regimes
             Investigated 500 mb Flow for Each Event Day

                                                      337.5    N    22.5


                                             292.5
                                                     NW


                                                W

                                             247.5   SW

                                                      202.5    S     157.5


   Surrounding Upper Air Sites Utilized Data Stratified by 45 Degree Increments
___________________________________________________________________________

              Determine any signal that might exist with respect to the
                origin of severe convection per specific flow regime
                        500 mb Flow Regimes



                                            Distribution of Events:
                            SW
        W                                       West (43%)
                                              Southwest (33%)
                                              Northwest (20%)
                   NW NS

Regime Distribution - Entire Study Period




                        Preferred flow regimes by month?
                  500 mb Flow Regimes
                       1997-2006 Flow Regimes
50.00%



40.00%



30.00%



20.00%



10.00%



0.00%

                 May               June               July
         South         Southwest   West   Northwest          North
500 mb Flow Regimes
                                                N
                             NW             337.5 – 22.5

                            292.5 - 337.5




                         W                   Flow
                                            Regimes
                      247.5 – 292.5




                              SW
                            247.5 – 202.5
                                                S
                                            202.5 – 157.5
500 mb Flow Regimes
                                                N
                             NW             337.5 – 22.5

                            292.5 - 337.5




                         W                   Flow
                                            Regimes
                      247.5 – 292.5




                              SW
                            247.5 – 202.5
                                                S
                                            202.5 – 157.5
                   Limitations

 NCDC National Mosaic Reflectivity Imagery
     Radar data available every 30 minutes to 1 hour
                 2 km radar resolution


     In-Depth Study Period Restricted
              to 10 Year Database

 Study Domain Narrowed to Goodland CWA
                    Closing Remarks
          May, June, and July climatological three-month
            maximum of severe weather for GLD CWA

                 ~ 285 CI event cases (1997 – 2006)

        Spatial distribution CI overall analogous with some
         clustering in identifiable topographical locations

      Temporal analysis established strong diurnal preference
       with regards to CI and 1st resultant severe weather type

Preferred flow regimes were favored in specific geographic locations

         Flow regimes tended to transition throughout the
          progression of months during the study period
 Acknowledgements
Albert Pietrycha (SOO – NWS GLD)
    NWS Goodland Resources




Questions ???

     Thank You !

         Contact Information:
      scott.blair@noaa.gov

								
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