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
0734 CDT Tuesday, September 18, 2018

This forecast is for Tuesday September 18, 2018
:

If the trigger temperature of 87.2 F/30.7 C is reached...then
   Thermal Soaring Index....................... Good
   Maximum rate of lift........................ 407 ft/min (2.1 m/s)
   Maximum height of thermals.................. 7595 ft MSL (6063 ft AGL)

Forecast maximum temperature................... 93.0 F/34.3 C
Time of trigger temperature.................... 1145 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................. 4768 ft MSL (3236 ft AGL)
Thermal soaring outlook for Wednesday 09/19.... Fair

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

Remarks... 

Sunrise/Sunset.................... 07:16:12 / 19:35:15 CDT
Total possible sunshine........... 12 hr 19 min 2 sec (739 min 2 sec)
Altitude of sun at 13:25:44 CDT... 53.29 degrees

Upper air data from numerical model forecast valid on 09/18/2018 at 0600 CDT

Freezing level.................. 17342 ft MSL (15810 ft AGL)
Convective condensation level... 9381 ft MSL (7849 ft AGL)
Lifted condensation level....... 8754 ft MSL (7221 ft AGL)
Lifted index.................... -0.3
K index......................... +18.4

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   -1.3  29.7   270    2    1   6.0   3.3   49.6 121.3    13.2      M    M
 17000    0.5  32.9   280    2    1   6.2   3.4   48.4 119.1    12.3      M    M
 16000    2.2  36.0   290    2    1   5.4   2.9   46.9 116.4    11.1      M    M
 15000    3.5  38.3   295    2    1   4.2   2.3   45.1 113.1     9.7      M    M
 14000    4.6  40.3   295    2    1   3.3   1.8   43.0 109.4     7.9      M    M
 13000    5.5  41.9   275    3    1   4.2   2.3   40.9 105.6     5.9      M    M
 12000    7.2  45.0   260    4    2   5.9   3.2   38.9 102.0     4.0      M    M
 11000    9.1  48.4   245    5    2   7.1   3.9   37.8 100.1     3.0      M    M
 10000   11.0  51.8   230    5    2   7.0   3.8   36.9  98.5     2.1      M    M
  9500   12.0  53.6   220    5    3   7.4   4.1   36.5  97.7     1.6      M    M
  9000   13.1  55.6   205    5    3   7.7   4.2   36.2  97.1     1.2      M    M
  8500   14.1  57.4   195    5    3   7.6   4.2   35.8  96.5     0.8      M    M
  8000   15.1  59.2   190    6    3   7.7   4.2   35.5  95.9     0.3      M    M
  7500   16.1  61.0   185    6    3   6.6   3.6   35.1  95.1    -0.2    395  2.0
  7000   16.9  62.4   185    7    3   6.8   3.7   34.6  94.2    -0.9    357  1.8
  6500   17.6  63.7   185    7    4   6.3   3.5   34.1  93.3    -1.6    319  1.6
  6000   18.4  65.1   190    7    4   8.3   4.6   33.5  92.3    -2.3    282  1.4
  5500   19.6  67.3   195    8    4   7.8   4.3   33.4  92.1    -2.6    231  1.2
  5000   20.7  69.3   205    9    5   8.2   4.5   33.2  91.7    -2.9    182  0.9
  4500   21.9  71.4   210   10    5   8.4   4.6   33.0  91.3    -3.1    131  0.7
  4000   23.2  73.8   215   11    6   8.7   4.8   32.8  91.1    -3.3     79  0.4
  3750   23.7  74.7   215   11    6   7.2   3.9   32.7  90.8    -3.5     54  0.3
  3500   24.2  75.6   220   12    6   6.2   3.4   32.4  90.4    -3.8     33  0.2
  3250   24.6  76.3   220   12    6   5.8   3.2   32.2  89.9    -4.1     12  0.1
  3000   25.0  77.0   220   12    6   4.5   2.5   31.8  89.3    -4.4      M    M
  2750   25.3  77.5   220   12    6   1.9   1.0   31.3  88.4    -4.9      M    M
  2500   25.2  77.4   215   12    6  -5.2  -2.9   30.5  86.9    -5.7      M    M
  2250   24.4  75.9   210   11    5  -9.6  -5.3   29.1  84.4    -7.2      M    M
  2000   23.7  74.7   200    9    5  -7.7  -4.2   27.7  81.9    -8.7      4  0.0
  1750   22.9  73.2   190    8    4 -11.0  -6.0   26.4  79.5   -10.2     19  0.1

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

           09/18/2018 at 0900 CDT          |       09/18/2018 at 1200 CDT        
                                           |
CAPE...  +718.8    LI...       -1.5        | CAPE... +1436.2    LI...       -2.8
CINH...   -77.2    K Index... +15.1        | CINH...    -4.8    K Index...  +9.6
                                           |
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  -2.1  28.2  265   3  2   5.9   3.2 |  -1.9  28.6  265   5  3   5.1   2.8
 17000  -0.3  31.5  300   3  2   6.1   3.4 |  -0.4  31.3  270   4  2   5.3   2.9
 16000   1.7  35.1  320   4  2   6.8   3.8 |   1.4  34.5  290   3  2   6.5   3.6
 15000   3.5  38.3  325   4  2   5.6   3.1 |   3.4  38.1  320   3  1   6.8   3.7
 14000   4.9  40.8  320   4  2   4.3   2.3 |   5.3  41.5  330   3  1   6.0   3.3
 13000   6.2  43.2  295   3  1   5.0   2.7 |   7.0  44.6  300   2  1   5.3   2.9
 12000   8.1  46.6  255   3  2   6.0   3.3 |   8.7  47.7  255   3  1   6.2   3.4
 11000  10.0  50.0  240   4  2   6.9   3.8 |  10.9  51.6  230   4  2   6.1   3.4
 10000  11.9  53.4  225   4  2   6.6   3.6 |  12.6  54.7  220   5  3   6.7   3.7
  9500  12.8  55.0  215   5  2   7.2   4.0 |  13.5  56.3  220   6  3   7.0   3.8
  9000  13.9  57.0  210   5  3   7.7   4.2 |  14.4  57.9  215   6  3   7.3   4.0
  8500  14.8  58.6  200   6  3   6.4   3.5 |  15.2  59.4  215   7  4   5.7   3.1
  8000  15.5  59.9  200   8  4   6.3   3.4 |  15.8  60.4  215   9  4   5.3   2.9
  7500  16.1  61.0  195   9  5   5.5   3.0 |  16.4  61.5  210  10  5   4.9   2.7
  7000  16.7  62.1  195  10  5   5.7   3.1 |  16.9  62.4  210  11  6   5.2   2.8
  6500  17.4  63.3  195  11  6   5.9   3.3 |  17.4  63.3  210  11  6   4.4   2.4
  6000  18.1  64.6  190  11  6   8.4   4.6 |  17.8  64.0  205  12  6   7.9   4.3
  5500  19.3  66.7  195  11  6   7.0   3.8 |  19.1  66.4  205  11  6   8.1   4.4
  5000  20.3  68.5  200  11  6   7.9   4.3 |  20.2  68.4  205  11  6   8.0   4.4
  4500  21.5  70.7  200  11  6   8.0   4.4 |  21.5  70.7  200  11  5  10.0   5.5
  4000  22.7  72.9  205  11  6   8.7   4.7 |  22.9  73.2  200  10  5   9.8   5.4
  3750  23.2  73.8  210  11  6   6.8   3.7 |  23.6  74.5  200  10  5   9.2   5.0
  3500  23.7  74.7  210  11  6   5.8   3.2 |  24.3  75.7  200  10  5   9.2   5.0
  3250  24.1  75.4  210  11  6   5.2   2.9 |  25.0  77.0  195  10  5   9.4   5.2
  3000  24.5  76.1  210  11  6   4.5   2.5 |  25.7  78.3  195  10  5   9.8   5.4
  2750  24.8  76.6  205  11  5   3.8   2.1 |  26.4  79.5  195   9  5  10.3   5.7
  2500  25.0  77.0  205  10  5   2.2   1.2 |  27.2  81.0  195   9  5  10.8   5.9
  2250  25.0  77.0  205   9  5   0.6   0.3 |  28.0  82.4  195   9  5  11.3   6.2
  2000  25.0  77.0  200   8  4   3.1   1.7 |  28.8  83.8  195   9  4  10.7   5.9
  1750  25.4  77.7  200   7  4  12.5   6.9 |  29.7  85.5  195   8  4  16.0   8.8

           09/18/2018 at 1500 CDT          |       09/18/2018 at 1800 CDT        
                                           |
CAPE... +1525.6    LI...       -2.6        | CAPE... +1588.0    LI...       -3.0
CINH...    -0.7    K Index...  +8.6        | CINH...   -12.9    K Index...  +8.8
                                           |
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  -1.3  29.7  280   6  3   4.6   2.5 |  -1.2  29.8  305   4  2   4.9   2.7
 17000  -0.1  31.8  285   5  2   4.5   2.5 |   0.0  32.0  320   4  2   4.5   2.5
 16000   1.5  34.7  290   4  2   6.0   3.3 |   1.6  34.9  320   3  1   5.5   3.0
 15000   3.4  38.1  295   3  1   7.0   3.8 |   3.4  38.1  320   2  1   6.9   3.8
 14000   5.6  42.1  315   2  1   7.2   3.9 |   5.5  41.9  325   1  1   7.8   4.3
 13000   7.7  45.9  315   2  1   6.5   3.6 |   7.9  46.2  340   1  0   7.5   4.1
 12000   9.6  49.3  280   2  1   6.2   3.4 |  10.1  50.2  325   1  0   6.7   3.7
 11000  11.8  53.2  250   4  2   5.6   3.1 |  12.6  54.7  270   2  1   5.9   3.2
 10000  13.2  55.8  240   5  3   5.4   3.0 |  14.0  57.2  250   3  2   4.8   2.7
  9500  13.7  56.7  235   6  3   5.5   3.0 |  14.5  58.1  245   4  2   4.5   2.5
  9000  14.3  57.7  235   7  4   5.1   2.8 |  14.8  58.6  245   6  3   4.2   2.3
  8500  14.8  58.6  230   8  4   5.2   2.8 |  15.0  59.0  240   7  4   4.5   2.5
  8000  15.4  59.7  225   9  5   5.3   2.9 |  15.4  59.7  230   8  4   4.7   2.6
  7500  16.0  60.8  220  10  5   6.5   3.5 |  15.9  60.6  225   9  5   7.3   4.0
  7000  16.7  62.1  215  10  5   6.9   3.8 |  16.9  62.4  215  10  5   8.0   4.4
  6500  17.6  63.7  210  10  5   7.4   4.1 |  17.9  64.2  210  10  5   7.4   4.0
  6000  18.5  65.3  205  10  5  11.6   6.4 |  19.0  66.2  205  10  5  11.7   6.4
  5500  20.3  68.5  205  10  5   8.5   4.7 |  20.7  69.3  200  11  5   8.1   4.4
  5000  21.7  71.1  200  10  5   8.1   4.4 |  22.1  71.8  195  11  6   7.6   4.2
  4500  23.0  73.4  200  10  5  11.0   6.0 |  23.3  73.9  195  11  6  10.8   5.9
  4000  24.7  76.5  195  10  5  10.9   6.0 |  24.8  76.6  190  11  6   9.8   5.4
  3750  25.4  77.7  195  10  5   9.4   5.1 |  25.5  77.9  190  11  6   9.3   5.1
  3500  26.1  79.0  195  10  5   9.0   5.0 |  26.2  79.2  185  11  6   9.3   5.1
  3250  26.8  80.2  195  10  5  10.3   5.7 |  26.9  80.4  185  11  6   9.2   5.1
  3000  27.6  81.7  195   9  5  10.5   5.8 |  27.6  81.7  185  11  6   9.4   5.1
  2750  28.3  82.9  195   9  5   9.1   5.0 |  28.3  82.9  185  11  6  10.0   5.5
  2500  29.0  84.2  195   9  5  10.2   5.6 |  29.0  84.2  180  11  5   9.1   5.0
  2250  29.8  85.6  195   9  5  11.8   6.5 |  29.6  85.3  180  10  5   7.9   4.3
  2000  30.6  87.1  195   9  4  10.3   5.6 |  30.1  86.2  180   9  5   8.5   4.6
  1750  31.4  88.5  190   8  4  13.2   7.3 |  30.6  87.1  175   8  4   5.0   2.7
________________________________________________________________________________

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