Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
175
UXUS97 KPUB 171237
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0633 MDT Sunday, August 17, 2025
This forecast is for Villa Grove, CO for Sunday, August 17, 2025:
If the trigger temperature of 65.8 F/18.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 957 ft/min (4.9 m/s)
Maximum height of thermals.................. 21601 ft MSL (12625 ft AGL)
Forecast maximum temperature................... 83.0 F/28.8 C
Time of trigger temperature.................... 0930 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Overcast opaque high
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 19195 ft MSL (10219 ft AGL)
Thermal soaring outlook for Monday 08/18....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:20:38 / 19:54:27 MDT
Total possible sunshine........... 13 hr 33 min 49 sec (813 min 49 sec)
Altitude of sun at 13:07:33 MDT... 64.82 degrees
Upper air data from numerical model forecast valid on 08/17/2025 at 0600 MDT
Freezing level.................. 15535 ft MSL (6559 ft AGL)
Convective condensation level... 16283 ft MSL (7307 ft AGL)
Lifted condensation level....... 19756 ft MSL (10780 ft AGL)
Lifted index.................... -4.2
K index......................... +4.1
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
--------------------------------------------------------------------------------
50000 -65.4 -85.7 235 14 7 1.3 0.7 M M M M M
45000 -60.3 -76.5 240 24 12 6.8 3.7 M M M M M
40000 -49.9 -57.8 230 30 16 7.6 4.2 M M M M M
38000 -45.4 -49.7 235 32 17 7.6 4.2 M M M M M
36000 -40.8 -41.4 240 34 18 7.5 4.1 M M M M M
34000 -36.5 -33.7 235 34 18 7.3 4.0 M M M M M
32000 -31.5 -24.7 235 34 18 6.9 3.8 M M M M M
30000 -28.0 -18.4 235 34 17 5.9 3.3 36.4 97.5 6.4 M M
29000 -26.2 -15.2 235 34 17 5.9 3.2 35.0 95.1 5.4 M M
28000 -24.3 -11.7 235 33 17 7.8 4.3 33.9 92.9 4.5 M M
27000 -22.0 -7.6 235 32 16 7.7 4.2 33.0 91.4 3.8 M M
26000 -19.7 -3.5 235 30 15 7.7 4.2 32.2 90.0 3.3 M M
25000 -17.4 0.7 235 28 14 7.5 4.1 31.6 88.9 2.8 M M
24000 -15.2 4.6 235 25 13 7.2 4.0 30.6 87.1 1.9 M M
23000 -13.0 8.6 230 23 12 7.2 4.0 29.7 85.5 1.2 M M
22000 -10.9 12.4 220 21 11 6.6 3.6 28.9 84.1 0.5 M M
21000 -9.1 15.6 220 20 10 5.9 3.2 27.5 81.5 -0.7 1111 5.6
20000 -7.4 18.7 220 19 10 6.0 3.3 26.2 79.2 -1.9 1029 5.2
19500 -6.5 20.3 220 18 9 6.2 3.4 25.6 78.1 -2.5 988 5.0
19000 -5.8 21.6 220 17 9 3.2 1.7 24.8 76.6 -3.2 953 4.8
18500 -5.3 22.5 225 17 9 3.5 1.9 23.8 74.8 -4.2 923 4.7
18000 -4.8 23.4 230 16 8 3.7 2.0 22.8 73.0 -5.2 893 4.5
17500 -4.3 24.3 235 14 7 4.2 2.3 21.8 71.2 -6.3 865 4.4
17000 -3.9 25.0 245 13 7 4.4 2.4 20.9 69.6 -7.3 836 4.2
16500 -2.9 26.8 250 12 6 9.9 5.4 20.5 68.9 -7.9 793 4.0
16000 -1.6 29.1 255 10 5 9.4 5.2 20.4 68.8 -8.1 738 3.7
15500 0.4 32.7 265 9 5 9.1 5.0 20.3 68.6 -8.3 655 3.3
15000 1.7 35.1 275 8 4 9.1 5.0 20.2 68.4 -8.5 600 3.1
14500 3.1 37.6 280 7 4 9.3 5.1 20.2 68.3 -8.6 545 2.8
14000 4.4 39.9 290 7 4 9.1 5.0 20.0 68.1 -8.8 490 2.5
13500 5.8 42.4 300 7 4 8.8 4.8 19.9 67.9 -9.0 436 2.2
13000 7.0 44.6 300 8 4 8.1 4.5 19.7 67.5 -9.2 383 1.9
12500 8.2 46.8 305 9 5 8.5 4.7 19.5 67.1 -9.5 332 1.7
12000 9.5 49.1 310 10 5 8.6 4.7 19.3 66.8 -9.7 279 1.4
11750 10.1 50.2 310 10 5 8.3 4.5 19.2 66.6 -9.9 253 1.3
11500 10.7 51.3 315 10 5 8.4 4.6 19.1 66.4 -10.0 228 1.2
11250 11.3 52.3 315 10 5 8.4 4.6 19.0 66.2 -10.2 202 1.0
11000 12.0 53.6 315 10 5 8.3 4.6 18.9 66.0 -10.3 176 0.9
10750 12.6 54.7 315 11 5 8.6 4.7 18.8 65.8 -10.5 150 0.8
10500 13.1 55.6 315 11 5 5.6 3.1 18.7 65.6 -10.7 126 0.6
10250 13.4 56.1 315 11 6 3.0 1.7 18.2 64.7 -11.2 112 0.6
10000 13.6 56.5 315 11 6 1.9 1.1 17.7 63.8 -11.7 98 0.5
9750 13.8 56.8 315 12 6 6.7 3.7 17.1 62.9 -12.3 85 0.4
9500 14.1 57.4 315 12 6 -3.8 -2.1 16.8 62.3 -12.7 66 0.3
9250 12.6 54.7 305 8 4 -36.3 -19.9 14.6 58.2 -15.0 105 0.5
9000 10.8 51.4 275 5 3 17.6 9.7 12.1 53.7 -17.5 151 0.8
8750 M M M M M M M M M M M M
8500 M M M M M M M M M M M M
8250 M M M M M M M M M M M M
8000 M M M M M M M M M M M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
08/17/2025 at 0900 MDT | 08/17/2025 at 1200 MDT
|
CAPE... +71.8 LI... +0.3 | CAPE... +1.6 LI... +2.0
CINH... -24.4 K Index... +0.8 | CINH... 0.0 K Index... -1.8
|
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
--------------------------------------------------------------------------------
50000 -65.1 -85.2 220 16 8 1.3 0.7 | -64.9 -84.8 210 17 9 1.1 0.6
45000 -60.1 -76.2 225 23 12 6.7 3.7 | -60.2 -76.4 215 23 12 6.5 3.6
40000 -49.9 -57.8 225 27 14 7.4 4.0 | -50.2 -58.4 225 29 15 7.4 4.0
38000 -45.5 -49.9 225 28 14 7.4 4.0 | -45.7 -50.3 230 29 15 7.4 4.0
36000 -41.1 -42.0 225 29 15 7.3 4.0 | -41.3 -42.3 230 28 15 7.3 4.0
34000 -36.8 -34.2 225 30 16 7.2 4.0 | -37.0 -34.6 230 29 15 7.2 4.0
32000 -32.4 -26.3 230 32 16 7.3 4.0 | -32.1 -25.8 230 31 16 6.9 3.8
30000 -28.3 -18.9 230 32 17 5.9 3.2 | -28.5 -19.3 225 31 16 5.9 3.3
29000 -26.6 -15.9 230 33 17 5.9 3.2 | -26.7 -16.1 225 31 16 5.9 3.2
28000 -24.6 -12.3 230 33 17 8.4 4.6 | -24.8 -12.6 225 30 16 8.2 4.5
27000 -22.2 -8.0 235 32 16 8.1 4.4 | -22.4 -8.3 230 30 15 7.9 4.3
26000 -19.8 -3.6 235 31 16 8.1 4.4 | -20.0 -4.0 230 30 15 7.9 4.3
25000 -17.3 0.9 240 30 16 7.6 4.1 | -17.7 0.1 235 29 15 7.5 4.1
24000 -15.3 4.5 240 28 14 6.9 3.8 | -15.5 4.1 240 27 14 7.0 3.8
23000 -13.2 8.2 235 25 13 6.9 3.8 | -13.4 7.9 240 24 13 7.0 3.8
22000 -11.2 11.8 235 22 11 6.3 3.5 | -11.3 11.7 245 22 11 6.5 3.5
21000 -9.4 15.1 230 21 11 5.8 3.2 | -9.6 14.7 245 20 10 6.0 3.3
20000 -7.7 18.1 230 20 10 5.8 3.2 | -7.8 18.0 250 19 10 6.0 3.3
19500 -6.9 19.6 225 19 10 5.9 3.3 | -6.9 19.6 250 18 9 6.0 3.3
19000 -6.3 20.7 230 18 9 2.3 1.3 | -6.3 20.7 250 17 9 2.5 1.4
18500 -5.9 21.4 235 16 8 2.9 1.6 | -5.9 21.4 255 16 8 2.9 1.6
18000 -5.6 21.9 245 15 8 3.9 2.2 | -5.5 22.1 260 15 8 4.3 2.4
17500 -5.0 23.0 250 13 6 4.8 2.6 | -4.8 23.4 265 12 6 5.6 3.0
17000 -4.4 24.1 255 10 5 5.2 2.8 | -4.1 24.6 265 10 5 6.4 3.5
16500 -3.3 26.1 260 9 5 9.3 5.1 | -3.0 26.6 270 9 4 9.7 5.3
16000 -2.1 28.2 260 8 4 9.0 4.9 | -1.6 29.1 270 8 4 9.4 5.2
15500 -0.7 30.7 265 7 4 9.3 5.1 | 0.5 32.9 270 8 4 10.0 5.5
15000 1.3 34.3 270 7 4 9.3 5.1 | 2.0 35.6 270 8 4 10.2 5.6
14500 2.7 36.9 275 7 4 8.9 4.9 | 3.4 38.1 270 8 4 8.8 4.8
14000 4.0 39.2 285 7 4 8.7 4.8 | 4.9 40.8 270 7 4 9.9 5.4
13500 5.3 41.5 295 7 4 9.0 5.0 | 6.4 43.5 275 7 4 11.5 6.3
13000 6.6 43.9 300 8 4 8.3 4.5 | 8.0 46.4 275 7 4 8.9 4.9
12500 7.9 46.2 310 9 5 8.7 4.7 | 9.4 48.9 275 7 3 9.9 5.4
12000 9.2 48.6 315 11 5 8.6 4.7 | 10.9 51.6 275 7 3 9.9 5.4
11750 9.8 49.6 315 11 6 8.4 4.6 | 11.6 52.9 275 6 3 9.5 5.2
11500 10.4 50.7 315 12 6 8.1 4.4 | 12.3 54.1 280 6 3 9.8 5.4
11250 10.9 51.6 315 12 6 7.9 4.3 | 13.0 55.4 280 6 3 9.9 5.4
11000 11.5 52.7 315 12 6 7.7 4.2 | 13.8 56.8 280 6 3 9.8 5.4
10750 12.1 53.8 315 12 6 9.0 5.0 | 14.5 58.1 280 6 3 10.4 5.7
10500 12.7 54.9 315 12 6 9.7 5.3 | 15.3 59.5 280 6 3 11.0 6.0
10250 13.4 56.1 315 11 6 8.9 4.9 | 16.2 61.2 280 6 3 10.7 5.8
10000 14.0 57.2 315 10 5 9.3 5.1 | 17.0 62.6 280 6 3 11.4 6.3
9750 14.6 58.3 310 10 5 8.9 4.9 | 17.8 64.0 280 5 3 8.7 4.8
9500 15.4 59.7 305 8 4 13.0 7.2 | 18.5 65.3 285 5 3 16.4 9.0
9250 16.6 61.9 305 7 4 20.7 11.4 | 20.5 68.9 280 5 3 36.9 20.2
9000 17.9 64.2 295 6 3 6.9 3.8 | 22.5 72.5 280 5 3 -1.7 -0.9
8750 M M M M M M M | M M M M M M M
8500 M M M M M M M | M M M M M M M
8250 M M M M M M M | M M M M M M M
8000 M M M M M M M | M M M M M M M
08/17/2025 at 1500 MDT | 08/17/2025 at 1800 MDT
|
CAPE... +6.2 LI... +0.3 | CAPE... +16.0 LI... -0.3
CINH... 0.0 K Index... +14.0 | CINH... -6.3 K Index... +21.9
|
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
--------------------------------------------------------------------------------
50000 -64.8 -84.6 215 19 10 0.6 0.3 | -64.5 -84.1 225 17 9 1.2 0.7
45000 -60.5 -76.9 225 27 14 6.6 3.6 | -59.9 -75.8 230 27 14 6.3 3.5
40000 -50.4 -58.7 240 29 15 7.7 4.2 | -50.1 -58.2 240 31 16 7.3 4.0
38000 -45.8 -50.4 235 31 16 7.7 4.2 | -45.7 -50.3 240 33 17 7.3 4.0
36000 -41.2 -42.2 235 33 17 7.6 4.2 | -41.4 -42.5 240 36 18 7.3 4.0
34000 -36.8 -34.2 230 34 17 7.3 4.0 | -36.3 -33.3 240 36 18 7.5 4.1
32000 -31.9 -25.4 230 35 18 6.8 3.7 | -31.7 -25.1 245 36 18 7.0 3.8
30000 -28.5 -19.3 225 33 17 5.5 3.0 | -28.4 -19.1 240 32 17 5.5 3.0
29000 -26.8 -16.2 225 32 16 5.5 3.0 | -26.8 -16.2 235 31 16 5.5 3.0
28000 -25.0 -13.0 220 31 16 7.7 4.2 | -25.0 -13.0 235 29 15 7.3 4.0
27000 -22.8 -9.0 225 29 15 7.5 4.1 | -22.9 -9.2 235 27 14 7.1 3.9
26000 -20.5 -4.9 230 28 14 7.5 4.1 | -20.8 -5.4 235 25 13 7.1 3.9
25000 -18.3 -0.9 235 26 14 7.4 4.1 | -18.6 -1.5 240 23 12 7.2 3.9
24000 -16.1 3.0 240 23 12 7.4 4.0 | -16.5 2.3 240 20 11 7.3 4.0
23000 -13.9 7.0 245 20 10 7.4 4.0 | -14.3 6.3 245 17 9 7.3 4.0
22000 -11.7 10.9 255 17 9 6.0 3.3 | -12.2 10.0 250 15 8 6.4 3.5
21000 -10.2 13.6 255 16 8 5.2 2.9 | -10.5 13.1 245 11 6 5.8 3.2
20000 -8.6 16.5 260 14 7 5.4 2.9 | -8.9 16.0 245 8 4 6.1 3.3
19500 -7.9 17.8 265 14 7 5.6 3.1 | -8.1 17.4 240 6 3 6.5 3.5
19000 -7.0 19.4 265 12 6 7.1 3.9 | -6.9 19.6 240 6 3 9.4 5.1
18500 -6.0 21.2 260 10 5 7.3 4.0 | -5.6 21.9 235 5 3 9.2 5.1
18000 -5.0 23.0 255 8 4 8.6 4.7 | -4.2 24.4 235 5 3 9.5 5.2
17500 -3.7 25.3 255 7 4 9.1 5.0 | -2.8 27.0 235 5 2 9.6 5.3
17000 -2.4 27.7 255 6 3 9.2 5.0 | -1.4 29.5 235 5 2 9.6 5.3
16500 -1.0 30.2 255 6 3 9.8 5.4 | 0.1 32.2 230 4 2 9.4 5.2
16000 0.5 32.9 255 6 3 9.8 5.4 | 2.2 36.0 225 4 2 9.4 5.2
15500 2.6 36.7 255 6 3 9.6 5.3 | 3.6 38.5 220 4 2 9.3 5.1
15000 4.1 39.4 255 5 3 9.7 5.3 | 5.0 41.0 215 4 2 9.3 5.1
14500 5.4 41.7 250 5 3 9.5 5.2 | 6.4 43.5 210 4 2 9.7 5.3
14000 7.0 44.6 250 5 3 10.4 5.7 | 7.8 46.0 200 4 2 9.7 5.3
13500 8.4 47.1 250 5 3 8.7 4.8 | 9.3 48.7 190 4 2 9.2 5.0
13000 9.9 49.8 250 5 3 10.7 5.9 | 10.7 51.3 185 4 2 9.8 5.4
12500 11.4 52.5 250 5 2 9.8 5.4 | 12.1 53.8 180 4 2 9.1 5.0
12000 12.9 55.2 250 5 2 9.9 5.4 | 13.4 56.1 175 4 2 9.6 5.3
11750 13.6 56.5 250 4 2 10.3 5.6 | 14.2 57.6 170 4 2 10.5 5.7
11500 14.4 57.9 250 4 2 9.9 5.5 | 14.9 58.8 170 4 2 9.8 5.4
11250 15.1 59.2 250 4 2 9.7 5.3 | 15.6 60.1 165 4 2 9.3 5.1
11000 15.9 60.6 250 4 2 9.8 5.4 | 16.3 61.3 165 4 2 9.4 5.1
10750 16.6 61.9 250 4 2 10.6 5.8 | 17.1 62.8 160 4 2 9.9 5.4
10500 17.4 63.3 250 4 2 11.1 6.1 | 17.8 64.0 160 4 2 10.3 5.6
10250 18.2 64.8 250 4 2 10.5 5.7 | 18.6 65.5 160 4 2 10.1 5.5
10000 19.0 66.2 250 4 2 11.4 6.3 | 19.4 66.9 155 4 2 10.2 5.6
9750 19.8 67.6 250 3 2 8.2 4.5 | 20.1 68.2 155 4 2 9.9 5.4
9500 20.5 68.9 250 3 2 15.2 8.3 | 20.9 69.6 155 4 2 12.3 6.8
9250 22.5 72.5 250 3 2 36.7 20.1 | 22.0 71.6 150 4 2 17.4 9.5
9000 24.5 76.1 250 3 2 0.5 0.3 | 23.1 73.6 150 4 2 9.9 5.4
8750 M M M M M M M | M M M M M M M
8500 M M M M M M M | M M M M M M M
8250 M M M M M M M | M M M M M M M
8000 M M M M M M M | M M M M M M M
________________________________________________________________________________
This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 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 near Villa Grove, Colorado at:
North Latitude: 38 deg 16 min 03 sec
West Longitude: 105 deg 53 min 37 sec
Elevation: 7986 feet (2434 meters)
and may not be representative of other areas along the Front Range of the
Colorado Rocky Mountains. 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.
042613