National Weather Service United States Department of Commerce

Soaring Forecast

 

 

 

It is emphasized...this soaring forecast information is valid only for the RAOB site area, and frequently will not apply to other areas of the state.

 


Soaring Forecast
National Weather Service Wichita, Kansas
0735 CDT Thursday, August 17, 2017

This forecast is for Thursday August 17, 2017
:

If the trigger temperature of 79.4 F/26.4 C is reached...then
   Thermal Soaring Index....................... Fair
   Maximum rate of lift........................ 294 ft/min (1.5 m/s)
   Maximum height of thermals.................. 7019 ft MSL (5481 ft AGL)

Forecast maximum temperature................... 88.0 F/31.6 C
Time of trigger temperature.................... 1100 CDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 5395 ft MSL (3857 ft AGL)
Thermal soaring outlook for Friday 08/18....... Fair

Wave Soaring Index............................. Not available

Remarks... 

Sunrise/Sunset.................... 06:49:05 / 20:22:08 CDT
Total possible sunshine........... 13 hr 33 min 3 sec (813 min 3 sec)
Altitude of sun at 13:35:37 CDT... 64.03 degrees

Upper air data from numerical model forecast valid on 08/17/2017 at 0600 CDT

Freezing level.................. 15174 ft MSL (13636 ft AGL)
Convective condensation level... 14237 ft MSL (12699 ft AGL)
Lifted condensation level....... 10740 ft MSL (9202 ft AGL)
Lifted index.................... +4.0
K index......................... -4.5

Height  Temperature  Wind  Wind Spd  Lapse Rate  ConvectionT  Thermal  Lift Rate
ft MSL  deg C deg F   Dir   kt  m/s  C/km F/kft  deg C deg F   Index    fpm  m/s
--------------------------------------------------------------------------------
 18000   -5.2  22.6   290   14    7   5.7   3.1   45.6 114.0    12.0      M    M
 17000   -3.5  25.7   295   14    7   5.8   3.2   44.2 111.5    10.9      M    M
 16000   -1.7  28.9   300   15    8   6.3   3.4   42.9 109.2     9.9      M    M
 15000    0.2  32.4   305   15    8   6.6   3.6   41.7 107.1     9.0      M    M
 14000    2.3  36.1   305   15    8   7.2   4.0   40.7 105.3     8.3      M    M
 13000    4.5  40.1   305   14    7   7.1   3.9   39.9 103.8     7.6      M    M
 12000    6.5  43.7   310   14    7   6.6   3.6   38.9 102.1     6.8      M    M
 11000    8.4  47.1   310   12    6   5.1   2.8   37.8 100.0     5.8      M    M
 10000   10.2  50.4   315   11    6   5.8   3.2   36.0  96.9     4.1      M    M
  9500   11.0  51.8   315   10    5   5.6   3.1   35.4  95.7     3.4      M    M
  9000   11.8  53.2   315   10    5   5.4   3.0   34.7  94.4     2.7      M    M
  8500   12.5  54.5   315   10    5   5.2   2.9   34.0  93.2     2.0      M    M
  8000   13.3  55.9   315   10    5   5.2   2.8   33.2  91.8     1.3      M    M
  7500   14.0  57.2   315    9    5   5.0   2.7   32.5  90.5     0.6      M    M
  7000   14.7  58.5   310    9    5   5.0   2.7   31.7  89.1    -0.1    289  1.5
  6500   15.4  59.7   310    9    5   4.2   2.3   30.9  87.7    -0.9    255  1.3
  6000   15.9  60.6   305    9    5   2.6   1.5   30.1  86.2    -1.8    223  1.1
  5500   16.4  61.5   305    9    5   5.6   3.1   29.1  84.4    -2.9    195  1.0
  5000   17.0  62.6   305    9    5   4.4   2.4   28.4  83.1    -3.7    162  0.8
  4500   17.4  63.3   310    9    5   3.6   2.0   27.5  81.4    -4.7    133  0.7
  4000   18.0  64.4   315    9    5   4.6   2.5   26.6  79.9    -5.7    102  0.5
  3750   18.2  64.8   320    9    5   3.3   1.8   26.2  79.1    -6.1     87  0.4
  3500   18.4  65.1   325    9    5   3.2   1.7   25.6  78.1    -6.7     75  0.4
  3250   18.6  65.5   330    9    5   4.5   2.4   25.2  77.3    -7.2     61  0.3
  3000   18.9  66.0   330   10    5   4.8   2.6   24.8  76.6    -7.7     44  0.2
  2750   19.2  66.6   335   10    5   3.9   2.1   24.4  75.9    -8.1     28  0.1
  2500   19.3  66.7   335   10    5   1.2   0.7   23.9  75.0    -8.8     17  0.1
  2250   19.3  66.7   330    9    5   0.6   0.3   23.2  73.7    -9.6     12  0.1
  2000   19.2  66.6   330    9    5  -0.6  -0.3   22.5  72.5   -10.4      7  0.0
  1750   18.7  65.7   325    8    4 -11.8  -6.5   21.4  70.5   -11.6     13  0.1

 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 

           08/17/2017 at 0900 CDT          |       08/17/2017 at 1200 CDT        
                                           |
CAPE...     0.0    LI...       +4.7        | CAPE...     0.0    LI...       +4.4
CINH...    -1.0    K Index... -16.5        | CINH...    -0.0    K Index...  +1.9
                                           |
Height Temperature  Wnd WndSpd  Lapse Rate | Temperature  Wnd WndSpd  Lapse Rate
ft MSL deg C deg F  Dir kt m/s  C/km F/kft | deg C deg F  Dir kt m/s  C/km F/kft
--------------------------------------------------------------------------------
 18000  -5.5  22.1  285  17  9   5.9   3.2 |  -6.0  21.2  280  17  9   6.2   3.4
 17000  -3.8  25.2  285  17  9   5.9   3.2 |  -4.1  24.6  285  17  9   6.2   3.4
 16000  -1.9  28.6  290  17  9   6.4   3.5 |  -2.2  28.0  285  17  9   6.6   3.6
 15000   0.1  32.2  295  17  9   6.6   3.6 |  -0.1  31.8  290  17  9   6.8   3.7
 14000   2.1  35.8  300  16  8   6.8   3.7 |   1.9  35.4  295  16  8   6.5   3.6
 13000   4.2  39.6  300  16  8   6.7   3.7 |   3.9  39.0  300  16  8   6.7   3.7
 12000   6.2  43.2  305  15  8   6.7   3.7 |   5.9  42.6  300  15  8   6.8   3.7
 11000   8.3  46.9  310  13  7   6.7   3.7 |   7.9  46.2  305  14  7   7.0   3.8
 10000  10.8  51.4  315  12  6   6.9   3.8 |  10.6  51.1  310  13  7   6.9   3.8
  9500  11.8  53.2  315  11  6   6.8   3.8 |  11.6  52.9  315  12  6   6.7   3.7
  9000  12.9  55.2  315  11  6   6.8   3.7 |  12.6  54.7  315  12  6   6.7   3.7
  8500  13.9  57.0  315  11  6   6.4   3.5 |  13.6  56.5  315  12  6   6.5   3.6
  8000  14.8  58.6  315  11  5   6.4   3.5 |  14.6  58.3  320  11  6   6.5   3.6
  7500  15.7  60.3  315  10  5   5.0   2.7 |  15.5  59.9  320  11  6   5.4   3.0
  7000  16.4  61.5  320  10  5   5.0   2.7 |  16.2  61.2  320  10  5   5.5   3.0
  6500  17.1  62.8  320  10  5   3.8   2.1 |  16.8  62.2  325  10  5   3.7   2.0
  6000  17.6  63.7  325  10  5   3.3   1.8 |  17.4  63.3  330   9  5   2.9   1.6
  5500  18.1  64.6  330  10  5   3.9   2.1 |  17.6  63.7  335   8  4   2.8   1.5
  5000  18.6  65.5  335  10  5   2.8   1.5 |  17.8  64.0  340   7  4   4.2   2.3
  4500  18.9  66.0  340  10  5   3.0   1.7 |  18.7  65.7  335   6  3   8.5   4.7
  4000  19.2  66.6  340   9  5   3.6   2.0 |  19.9  67.8  335   5  3  10.3   5.6
  3750  19.3  66.7  340   9  5   2.7   1.5 |  20.7  69.3  335   5  3   9.3   5.1
  3500  19.3  66.7  340   9  5   2.8   1.5 |  21.4  70.5  335   5  3   9.7   5.3
  3250  19.5  67.1  340   9  5   3.8   2.1 |  22.1  71.8  335   5  3  10.5   5.8
  3000  19.6  67.3  340   9  4   4.1   2.2 |  22.9  73.2  335   5  3  10.3   5.6
  2750  19.8  67.6  335   8  4   5.6   3.1 |  23.6  74.5  335   5  2  10.3   5.6
  2500  20.2  68.4  335   8  4   7.5   4.1 |  24.4  75.9  335   5  2  10.8   5.9
  2250  20.7  69.3  330   7  4   7.1   3.9 |  25.2  77.4  335   4  2  10.2   5.6
  2000  21.1  70.0  330   7  3   9.9   5.4 |  26.0  78.8  335   4  2  12.7   7.0
  1750  22.1  71.8  330   6  3  18.8  10.3 |  27.2  81.0  335   4  2  21.4  11.8

           08/17/2017 at 1500 CDT          |       08/17/2017 at 1800 CDT        
                                           |
CAPE...     0.0    LI...       +3.2        | CAPE...     0.0    LI...       +2.0
CINH...    -0.0    K Index... +15.4        | CINH...     0.0    K Index... +21.7
                                           |
Height Temperature  Wnd WndSpd  Lapse Rate | Temperature  Wnd WndSpd  Lapse Rate
ft MSL deg C deg F  Dir kt m/s  C/km F/kft | deg C deg F  Dir kt m/s  C/km F/kft
--------------------------------------------------------------------------------
 18000  -6.0  21.2  280  17  9   5.6   3.1 |  -6.4  20.5  285  17  9   6.2   3.4
 17000  -4.3  24.3  285  16  8   6.1   3.3 |  -4.4  24.1  285  16  8   6.8   3.7
 16000  -2.5  27.5  285  15  8   6.4   3.5 |  -2.4  27.7  290  15  8   7.2   3.9
 15000  -0.6  30.9  285  15  8   6.5   3.6 |  -0.3  31.5  290  14  7   6.9   3.8
 14000   1.4  34.5  290  15  8   6.8   3.7 |   1.6  34.9  290  13  7   6.8   3.7
 13000   3.4  38.1  290  14  7   6.9   3.8 |   3.6  38.5  290  13  6   6.5   3.6
 12000   5.5  41.9  295  14  7   7.6   4.2 |   5.5  41.9  295  12  6   7.2   3.9
 11000   7.8  46.0  305  13  7   7.6   4.2 |   7.6  45.7  295  11  6   8.2   4.5
 10000  10.6  51.1  310  12  6   7.7   4.2 |  10.6  51.1  300  10  5   8.1   4.5
  9500  11.8  53.2  310  12  6   7.3   4.0 |  11.8  53.2  305  10  5   7.6   4.2
  9000  12.9  55.2  315  11  6   7.3   4.0 |  12.9  55.2  310   9  5   7.4   4.1
  8500  13.9  57.0  315  11  6   5.3   2.9 |  14.0  57.2  310   8  4   6.6   3.6
  8000  14.6  58.3  320  10  5   4.9   2.7 |  15.0  59.0  315   7  4   6.6   3.6
  7500  15.3  59.5  325   8  4   4.9   2.7 |  15.9  60.6  320   6  3   5.1   2.8
  7000  15.9  60.6  325   7  4   5.0   2.7 |  16.7  62.1  320   5  2   5.2   2.8
  6500  16.6  61.9  330   6  3   5.8   3.2 |  17.5  63.5  320   3  2   6.0   3.3
  6000  17.3  63.1  330   4  2   5.9   3.2 |  18.2  64.8  315   1  1   5.5   3.0
  5500  18.5  65.3  330   4  2  10.2   5.6 |  19.3  66.7  305   1  0  10.1   5.5
  5000  19.8  67.6  330   3  2   9.4   5.2 |  20.6  69.1  000   0  0   9.0   4.9
  4500  21.2  70.2  330   3  1  10.3   5.6 |  22.0  71.6  180   1  0  10.1   5.5
  4000  22.8  73.0  335   3  1  10.2   5.6 |  23.5  74.3  170   1  0  10.3   5.7
  3750  23.5  74.3  335   3  1   9.7   5.3 |  24.3  75.7  165   1  0   9.5   5.2
  3500  24.2  75.6  335   3  1   9.7   5.3 |  25.0  77.0  165   1  0   9.4   5.2
  3250  24.9  76.8  335   2  1   9.6   5.3 |  25.7  78.3  165   1  1   9.6   5.3
  3000  25.7  78.3  335   2  1  10.0   5.5 |  26.4  79.5  165   1  1   9.8   5.4
  2750  26.4  79.5  335   2  1  10.5   5.8 |  27.1  80.8  160   1  1  10.1   5.5
  2500  27.2  81.0  335   2  1  10.7   5.9 |  27.9  82.2  160   1  1  10.1   5.5
  2250  28.0  82.4  335   2  1  10.3   5.7 |  28.6  83.5  160   1  1  10.2   5.6
  2000  28.8  83.8  335   2  1  11.5   6.3 |  29.4  84.9  160   1  1   9.8   5.4
  1750  29.8  85.6  335   2  1  17.2   9.4 |  30.0  86.0  160   1  1   9.5   5.2
________________________________________________________________________________

This product is issued twice per day, once by approximately 0630 CST/0730 CDT 
(1330 UTC) and again by approximately 1830 CST/1930 CDT (0130 UTC).  It is not 
continuously monitored nor updated after its initial issuance. 

The information contained herein is based on rawinsonde observation and/or
numerical weather prediction model data taken at the Wichita Gliderport at 

                   North Latitude: 37 deg 45 min 48.420 sec
                   West Longitude: 97 deg 10 min 41.220 sec
                   Elevation: 1380 feet (420 meters)

and may not be representative of other locations around the Wichita area.  Note
that some elevations in numerical weather prediction models differ from actual
station elevations, which can lead to data which appear to be below ground.
Erroneous data such as these should not be used.

The content and format of this report as well as the issuance times are subject
to change without prior notice.  Comments and suggestions are welcome and should
be directed to one of the addresses or phone numbers shown at the bottom of this
page.  To expedite a response to comments, be sure to mention your interest in 
the soaring forecast.

DEFINITIONS:

CAPE (Convective Available Potential Energy) - An integrated measure of the
     energy available for convective development, also known as the positive 
     area on a thermodynamic diagram.  Units are Joules per kilogram.  Larger
     values are indicative of greater instability and the possibility of 
     stronger convective activity, including thunderstorms.  Values around or
     greater than 1000 suggest the possibility of severe weather should
     convective activity develop.

CIN (Convective Inhibition) - An integrated measure of the amount of energy
     needed to initiate convective activity, also known as the negative area on
     a thermodynamic diagram.  Units are Joules per kilogram.  The more negative
     this number, the more energy is required to initiate convection.  This
     inhibitive energy can be overcome through surface heating, cooling aloft,
     lifting mechanisms (orographic, frontal, gravity waves, etc.)

Convective Condensation Level - The height to which an air parcel possessing the
     average saturation mixing ratio in the lowest 4000 feet of the airmass,
     if heated sufficiently from below, will rise dry adiabatically until it 
     just becomes saturated.  It estimates the base of cumulus clouds that are
     produced by surface heating only.

Convection Temperature (ConvectionT) - The surface temperature required to make
     the airmass dry adiabatic up to the given level.  It can be considered a
     "trigger temperature" for that level.

Freezing Level - The height where the temperature is zero degrees Celsius.

Height of Stable Layer - The height (between 12,000 and 18,000 feet above 
     mean sea level) where the smallest lapse rate exists.  The location and
     existence of this feature is important in the generation of mountain 
     waves.

K Index - A measure of stability which combines the temperature difference
     between approximately 5,000 and 18,000 feet above the surface, the amount
     of moisture at approximately 5,000 feet above the surface, and a measure
     of the dryness at approximately 10,000 feet above the surface.  Larger 
     positive numbers indicate more instability and a greater likelihood of 
     thunderstorm development.  One interpretation of K index values regarding
     soaring in the western United States is given in WMO Technical Note 158 
     and is reproduced in the following table:

          below -10    no or weak thermals
           -10 to 5    dry thermals or 1/8 cumulus with moderate thermals
            5 to 15    good soaring conditions
           15 to 20    good soaring conditions with occasional showers
           20 to 30    excellent soaring conditions, but increasing
                       probability of showers and thunderstorms
           above 30    more than 60 percent probability of thunderstorms

Lapse Rate - The change with height of the temperature. Negative values indicate
     inversions. 

Lifted Condensation Level - The height to which an air parcel possessing the 
     average dew point in the lowest 4000 feet of the airmass and the forecast
     maximum temperature must be lifted dry adiabatically to attain saturation.

Lifted Index (LI) - The difference between the environmental temperature at a
     level approximately 18,000 feet above the surface and the temperature of
     an air parcel lifted dry adiabatically from the surface to its lifted
     condensation level and then pseudoadiabatically thereafter to this same
     level.  The parcel's initial temperature is the forecast maximum 
     temperature and its dew point is the average dew point in the lowest 4000
     feet of the airmass.  Negative values are indicative of instability with
     positive values showing stable conditions.

Lift Rate - An experimental estimate of the strength of thermals.  It is
     computed the same way as the maximum rate of lift but uses the actual
     level rather than the maximum height of thermals in the calculation.
     Also, none of the empirical adjustments based on cloudiness and K-index
     are applied to these calculations.

Maximum Height of Thermals - The height where the dry adiabat through the
     forecast maximum temperature intersects the environmental temperature.

Maximum Rate of Lift - An estimate of the maximum strength of thermals.  It 
     is computed from an empirical formula which combines the expected maximum
     height of thermals with the difference in the environmental temperatures 
     between the maximum height of thermals and the temperature 4,000 feet 
     above the ground.  After this computation, further empirical adjustments
     are made based on the value of the K-index and the amount and opacity of
     middle and high level cloudiness expected between the time of trigger
     temperature and the time of overdevelopment.  

Middle/High Clouds - The amount and opacity of middle (altostratus, altocumulus)
     or high (cirrus, cirrostratus, cirrocumulus) clouds.  Broken means that
     between 60% and 90% of the sky is covered by the cloud, with overcast
     conditions occurring when more than 90% of the sky is covered by the cloud.
     Thin implies that the clouds are predominantly transparent, meaning that
     some sunlight is reaching the ground, in contrast to opaque which suggests
     that little sunlight is reaching the ground.
  
Potential Height of Wave - The minimum of the following two heights: 
     1. Level above the height of stable layer (or 14,000 feet if none exists)
        where the wind direction changes by 30 degrees or more
     2. Level above the height of stable layer (or 14,000 feet if none exists)
        where the wind speed no longer increases with height

PVA/NVA - Positive vorticity advection (PVA)/negative vorticity advection (NVA)
     on the 500 millibar isobaric surface (approximately 18,000 feet above mean
     sea level).  Weak PVA has been shown to assist in mountain wave soaring.

Soaring Window - The time between the time the trigger temperature is reached
                 and the time of overdevelopment.

Thermal Index - The difference between the environmental temperature and the
     temperature at a particular level determined by following the dry adiabat
     through the forecast maximum temperature up to that level.  Negative values
     are indicative of thermal lift.

Thermal Soaring Index - An adjective rating (for sailplanes) based on the 
     computed maximum rate of lift, and the wind speed and middle and high
     cloud cover expected during the soaring window (the time of the trigger
     temperature and the time of overdevelopment) according to the following:

                 Maximum rate of lift        Adjective Rating
                      >= 800 fpm                 Excellent
                 >= 400 and < 800 fpm              Good
                 >= 200 and < 400 fpm              Fair
                       < 200 fpm                   Poor  

Time of Overdevelopment - The time one or more of the following phenomena,
     which essentially shut off thermal lift, is expected to occur:
     1. formation of broken to overcast convective cloud cover
     2. formation of scattered to numerous downbursts
     3. initiation of widespread precipitation

Time of Trigger Temperature - The time the surface temperature is expected to
     reach the trigger temperature.

Trigger Temperature - The surface temperature required to make the first 4000
     feet of the atmosphere dry adiabatic.

Wave Soaring Index - An empirical, adjective rating (for sailplanes) which 
     attempts to combine a variety of phenomena important in mountain wave
     soaring into a single index number.  Objective points are assigned to
     these phenomena: wind speed and direction at 14,000 ft MSL, the static
     stability in the 12,000-18,000 ft MSL layer, the wind speed gradient above
     the stable layer, jet stream location and frontal and upper trough 
     movements.

051515