Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
703
UXUS97 KPUB 301219
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0618 MDT Saturday, August 30, 2025
This forecast is for Villa Grove, CO for Saturday, August 30, 2025:
If the trigger temperature of 59.8 F/15.4 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 422 ft/min (2.1 m/s)
Maximum height of thermals.................. 16515 ft MSL (7542 ft AGL)
Forecast maximum temperature................... 72.0 F/22.7 C
Time of trigger temperature.................... 0845 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 15316 ft MSL (6342 ft AGL)
Thermal soaring outlook for Sunday 08/31....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:32:00 / 19:36:06 MDT
Total possible sunshine........... 13 hr 4 min 6 sec (784 min 6 sec)
Altitude of sun at 13:04:03 MDT... 60.42 degrees
Upper air data from numerical model forecast valid on 08/30/2025 at 0600 MDT
Freezing level.................. 15273 ft MSL (6300 ft AGL)
Convective condensation level... 13775 ft MSL (4802 ft AGL)
Lifted condensation level....... 16145 ft MSL (7172 ft AGL)
Lifted index.................... -4.0
K index......................... -0.3
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 -65.2 -85.4 250 34 17 2.3 1.2 M M M M M
45000 -59.8 -75.6 250 53 27 6.5 3.6 M M M M M
40000 -49.3 -56.7 250 70 36 7.5 4.1 M M M M M
38000 -44.8 -48.6 245 70 36 7.5 4.1 M M M M M
36000 -40.4 -40.7 245 69 36 7.5 4.1 M M M M M
34000 -36.3 -33.3 245 68 35 6.7 3.7 M M M M M
32000 -32.3 -26.1 245 67 34 6.7 3.7 M M M M M
30000 -28.7 -19.7 250 60 31 6.0 3.3 36.7 98.1 11.5 M M
29000 -26.9 -16.4 250 57 29 6.0 3.3 35.3 95.6 10.5 M M
28000 -25.1 -13.2 250 53 27 5.5 3.0 34.1 93.3 9.6 M M
27000 -23.7 -10.7 255 48 24 3.5 1.9 31.2 88.1 7.4 M M
26000 -22.6 -8.7 260 43 22 3.5 1.9 28.9 84.0 5.6 M M
25000 -21.6 -6.9 265 39 20 4.4 2.4 26.8 80.2 3.8 M M
24000 -19.3 -2.7 265 37 19 8.6 4.7 26.1 78.9 3.2 M M
23000 -16.7 1.9 270 35 18 8.6 4.7 25.6 78.2 2.9 M M
22000 -14.1 6.6 270 34 17 8.8 4.9 25.3 77.6 2.6 M M
21000 -11.4 11.5 270 31 16 9.4 5.1 25.1 77.2 2.5 M M
20000 -8.6 16.5 275 28 14 9.4 5.1 25.0 77.0 2.4 M M
19500 -7.2 19.0 275 26 13 9.4 5.2 25.0 76.9 2.4 M M
19000 -5.8 21.6 275 25 13 9.1 5.0 24.9 76.8 2.3 M M
18500 -4.4 24.1 275 23 12 9.1 5.0 24.8 76.7 2.3 M M
18000 -3.0 26.6 280 22 11 8.0 4.4 24.7 76.5 2.3 M M
17500 -2.1 28.2 275 20 10 5.6 3.1 24.1 75.4 1.7 M M
17000 -1.2 29.8 275 18 9 6.0 3.3 23.4 74.2 1.1 M M
16500 -0.7 30.7 275 17 9 1.8 1.0 22.5 72.5 0.2 M M
16000 -0.5 31.1 270 16 8 2.7 1.5 21.3 70.3 -1.1 605 3.1
15500 -0.3 31.5 270 15 7 4.0 2.2 20.3 68.5 -2.4 584 3.0
15000 0.2 32.4 275 14 7 4.3 2.4 19.3 66.8 -3.4 555 2.8
14500 0.7 33.3 275 14 7 4.9 2.7 18.5 65.3 -4.4 525 2.7
14000 1.9 35.4 275 13 7 6.1 3.4 17.6 63.6 -5.4 466 2.4
13500 2.8 37.0 280 13 6 6.0 3.3 17.0 62.6 -6.0 425 2.2
13000 3.7 38.7 285 12 6 6.6 3.6 16.5 61.7 -6.6 383 1.9
12500 4.6 40.3 290 11 6 6.5 3.6 16.0 60.8 -7.1 340 1.7
12000 5.5 41.9 295 10 5 6.5 3.5 15.5 59.8 -7.7 299 1.5
11750 6.0 42.8 300 10 5 6.8 3.8 15.2 59.4 -8.0 278 1.4
11500 6.4 43.5 305 10 5 6.6 3.6 15.0 59.0 -8.3 256 1.3
11250 6.9 44.4 305 10 5 6.5 3.5 14.7 58.5 -8.6 235 1.2
11000 7.3 45.1 305 9 5 6.2 3.4 14.5 58.1 -8.9 214 1.1
10750 7.8 46.0 310 9 5 7.2 3.9 14.2 57.6 -9.2 194 1.0
10500 8.3 46.9 310 9 5 7.0 3.8 14.1 57.3 -9.4 171 0.9
10250 8.7 47.7 310 9 4 5.6 3.1 13.8 56.8 -9.8 152 0.8
10000 9.0 48.2 310 8 4 4.8 2.6 13.5 56.2 -10.2 133 0.7
9750 9.4 48.9 310 7 4 7.5 4.1 13.1 55.6 -10.6 115 0.6
9500 9.9 49.8 305 6 3 4.0 2.2 13.0 55.3 -10.8 92 0.5
9250 9.7 49.5 300 4 2 -11.2 -6.2 12.0 53.6 -11.8 93 0.5
9000 9.1 48.4 275 2 1 8.4 4.6 10.7 51.3 -13.1 102 0.5
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 * * * * * *
08/30/2025 at 0900 MDT | 08/30/2025 at 1200 MDT
|
CAPE... +387.5 LI... -0.3 | CAPE... +436.5 LI... -1.7
CINH... -1.0 K Index... -1.1 | CINH... 0.0 K Index... +14.6
|
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
--------------------------------------------------------------------------------
50000 -64.3 -83.7 255 36 19 2.3 1.3 | -64.0 -83.2 250 37 19 2.8 1.5
45000 -59.2 -74.6 255 58 30 5.8 3.2 | -58.5 -73.3 255 60 31 5.7 3.1
40000 -49.7 -57.5 255 78 40 7.5 4.1 | -49.2 -56.6 255 77 40 7.3 4.0
38000 -45.2 -49.4 250 77 40 7.5 4.1 | -44.8 -48.6 255 77 40 7.3 4.0
36000 -40.7 -41.3 245 76 39 7.6 4.2 | -40.5 -40.9 255 77 40 7.5 4.1
34000 -36.7 -34.1 250 72 37 6.6 3.6 | -36.9 -34.4 255 69 36 5.7 3.1
32000 -32.7 -26.9 250 69 35 6.6 3.6 | -33.5 -28.3 255 60 31 5.7 3.1
30000 -29.8 -21.6 250 57 29 4.3 2.4 | -30.4 -22.7 260 51 26 5.0 2.8
29000 -28.5 -19.3 255 50 26 4.3 2.4 | -28.9 -20.0 260 47 24 5.0 2.8
28000 -26.9 -16.4 255 42 21 5.2 2.9 | -27.0 -16.6 265 41 21 5.8 3.2
27000 -25.2 -13.4 255 38 20 5.5 3.0 | -25.1 -13.2 265 38 19 6.2 3.4
26000 -23.6 -10.5 255 35 18 5.5 3.0 | -23.3 -9.9 265 34 18 6.2 3.4
25000 -21.9 -7.4 260 31 16 5.9 3.2 | -21.5 -6.7 265 31 16 6.2 3.4
24000 -19.5 -3.1 255 30 15 8.5 4.7 | -19.4 -2.9 265 29 15 6.9 3.8
23000 -17.0 1.4 255 29 15 8.5 4.7 | -17.4 0.7 265 27 14 6.9 3.8
22000 -14.5 5.9 255 28 14 8.6 4.7 | -15.3 4.5 265 26 13 7.2 4.0
21000 -11.9 10.6 260 26 13 8.8 4.8 | -12.9 8.8 265 23 12 8.3 4.5
20000 -9.2 15.4 265 23 12 8.8 4.8 | -10.5 13.1 270 21 11 8.3 4.6
19500 -7.9 17.8 265 23 12 9.0 4.9 | -9.3 15.3 275 20 10 8.6 4.7
19000 -6.7 19.9 270 21 11 6.7 3.7 | -8.2 17.2 275 19 10 6.0 3.3
18500 -5.7 21.7 270 20 10 6.7 3.7 | -7.4 18.7 275 17 9 6.2 3.4
18000 -4.7 23.5 270 18 9 6.2 3.4 | -6.5 20.3 280 15 8 6.2 3.4
17500 -3.9 25.0 270 17 9 5.4 2.9 | -5.7 21.7 285 14 7 6.1 3.4
17000 -3.2 26.2 275 15 8 5.7 3.1 | -4.9 23.2 290 12 6 6.3 3.5
16500 -2.6 27.3 275 14 7 3.2 1.7 | -4.0 24.8 295 11 5 5.7 3.1
16000 -2.2 28.0 275 13 7 3.8 2.1 | -3.2 26.2 300 9 5 5.7 3.1
15500 -1.8 28.8 280 12 6 5.4 2.9 | -2.4 27.7 305 8 4 5.9 3.2
15000 -1.0 30.2 285 11 6 6.0 3.3 | -1.2 29.8 310 8 4 6.0 3.3
14500 -0.2 31.6 295 10 5 6.0 3.3 | -0.3 31.5 315 7 4 6.4 3.5
14000 1.1 34.0 305 9 4 6.3 3.4 | 0.6 33.1 315 7 4 6.2 3.4
13500 2.0 35.6 315 8 4 7.1 3.9 | 1.5 34.7 320 6 3 8.6 4.7
13000 2.9 37.2 325 8 4 5.6 3.1 | 2.7 36.9 330 5 3 8.1 4.5
12500 3.7 38.7 335 9 4 6.4 3.5 | 3.9 39.0 340 4 2 9.6 5.3
12000 4.8 40.6 340 9 5 6.9 3.8 | 5.5 41.9 350 4 2 10.1 5.5
11750 5.2 41.4 345 9 5 6.3 3.5 | 6.2 43.2 355 4 2 9.0 4.9
11500 5.7 42.3 345 9 5 6.6 3.6 | 6.9 44.4 355 4 2 9.6 5.3
11250 6.2 43.2 345 10 5 6.9 3.8 | 7.6 45.7 360 4 2 10.2 5.6
11000 6.6 43.9 340 10 5 6.7 3.7 | 8.4 47.1 360 4 2 10.1 5.5
10750 7.1 44.8 340 10 5 7.2 3.9 | 9.1 48.4 360 4 2 10.1 5.6
10500 7.6 45.7 335 10 5 8.7 4.8 | 9.9 49.8 005 4 2 10.6 5.8
10250 8.3 46.9 335 10 5 9.4 5.1 | 10.7 51.3 005 4 2 10.7 5.9
10000 8.9 48.0 330 9 5 9.7 5.3 | 11.5 52.7 005 4 2 11.4 6.3
9750 9.6 49.3 325 9 4 8.3 4.5 | 12.3 54.1 010 4 2 8.6 4.7
9500 10.2 50.4 325 8 4 12.3 6.8 | 13.0 55.4 010 4 2 14.3 7.9
9250 11.5 52.7 325 7 4 23.3 12.8 | 14.7 58.5 010 4 2 32.4 17.8
9000 12.9 55.2 320 6 3 3.0 1.7 | 16.5 61.7 015 3 2 0.5 0.3
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
08/30/2025 at 1500 MDT | 08/30/2025 at 1800 MDT
|
CAPE... +398.2 LI... -2.3 | CAPE... +441.7 LI... -3.7
CINH... 0.0 K Index... +22.7 | CINH... -1.5 K Index... +26.1
|
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 -64.2 -83.6 255 38 19 2.5 1.4 | -64.6 -84.3 260 42 21 1.8 1.0
45000 -58.9 -74.0 255 59 31 5.9 3.2 | -59.9 -75.8 260 62 32 6.2 3.4
40000 -49.4 -56.9 260 75 38 7.2 3.9 | -50.1 -58.2 260 71 37 6.8 3.7
38000 -45.1 -49.2 260 68 35 7.2 3.9 | -46.0 -50.8 260 62 32 6.8 3.7
36000 -40.8 -41.4 260 61 32 7.3 4.0 | -41.9 -43.4 265 53 27 6.8 3.7
34000 -37.1 -34.8 265 56 29 6.1 3.4 | -37.4 -35.3 270 47 24 7.6 4.2
32000 -33.4 -28.1 265 52 27 6.1 3.3 | -32.8 -27.0 280 44 22 7.7 4.2
30000 -30.1 -22.2 270 46 24 5.4 3.0 | -29.2 -20.6 285 40 21 5.6 3.1
29000 -28.4 -19.1 275 43 22 5.4 3.0 | -27.5 -17.5 285 39 20 5.6 3.1
28000 -26.4 -15.5 280 39 20 6.1 3.4 | -25.4 -13.7 290 37 19 5.7 3.1
27000 -24.5 -12.1 280 37 19 6.3 3.5 | -23.7 -10.7 290 34 18 5.7 3.1
26000 -22.6 -8.7 280 34 17 6.3 3.5 | -22.0 -7.6 290 32 16 5.7 3.1
25000 -20.7 -5.3 280 31 16 6.4 3.5 | -20.3 -4.5 295 30 15 5.9 3.2
24000 -18.7 -1.7 285 29 15 6.8 3.7 | -18.4 -1.1 295 28 14 6.3 3.5
23000 -16.7 1.9 285 27 14 6.8 3.7 | -16.5 2.3 290 26 13 6.4 3.5
22000 -14.7 5.5 285 25 13 6.9 3.8 | -14.7 5.5 290 24 12 6.4 3.5
21000 -12.6 9.3 285 24 12 7.0 3.9 | -12.9 8.8 290 21 11 6.2 3.4
20000 -10.6 12.9 285 22 11 7.2 4.0 | -11.2 11.8 290 19 10 6.3 3.5
19500 -9.6 14.7 285 21 11 7.4 4.1 | -10.3 13.5 290 18 9 6.3 3.4
19000 -8.6 16.5 285 20 10 6.5 3.6 | -9.3 15.3 290 17 9 8.0 4.4
18500 -7.7 18.1 285 19 10 6.6 3.6 | -8.2 17.2 295 16 8 7.9 4.3
18000 -6.8 19.8 285 17 9 6.5 3.6 | -7.0 19.4 295 15 8 7.4 4.1
17500 -5.8 21.6 290 16 8 6.4 3.5 | -6.1 21.0 295 15 8 6.8 3.7
17000 -5.0 23.0 290 15 8 6.4 3.5 | -5.1 22.8 300 16 8 6.7 3.7
16500 -4.0 24.8 295 14 7 6.7 3.7 | -4.0 24.8 300 15 8 8.3 4.6
16000 -3.1 26.4 300 14 7 6.7 3.7 | -2.9 26.8 295 15 8 8.2 4.5
15500 -2.1 28.2 305 13 7 7.1 3.9 | -1.7 28.9 295 14 7 7.9 4.3
15000 -1.1 30.0 305 12 6 7.4 4.0 | -0.6 30.9 290 13 7 7.9 4.3
14500 0.4 32.7 300 9 5 8.3 4.6 | 0.5 32.9 290 12 6 7.8 4.3
14000 1.8 35.2 305 7 3 9.5 5.2 | 2.5 36.5 290 10 5 9.6 5.3
13500 3.2 37.8 305 4 2 10.0 5.5 | 4.0 39.2 290 9 5 10.5 5.8
13000 4.6 40.3 310 3 2 9.8 5.4 | 5.4 41.7 295 8 4 8.8 4.8
12500 6.1 43.0 325 3 1 9.7 5.3 | 6.7 44.1 300 7 3 9.4 5.2
12000 7.5 45.5 335 3 1 10.0 5.5 | 8.2 46.8 310 5 2 9.4 5.1
11750 8.3 46.9 340 3 1 10.9 6.0 | 8.8 47.8 320 4 2 8.8 4.8
11500 9.1 48.4 350 3 1 10.1 5.5 | 9.5 49.1 345 3 2 9.0 4.9
11250 9.8 49.6 355 3 1 9.5 5.2 | 10.1 50.2 010 3 1 9.1 5.0
11000 10.5 50.9 360 3 1 9.3 5.1 | 10.8 51.4 030 3 2 8.9 4.9
10750 11.2 52.2 005 3 1 10.7 5.9 | 11.5 52.7 045 4 2 10.2 5.6
10500 12.1 53.8 010 3 1 11.2 6.1 | 12.3 54.1 050 5 2 10.7 5.9
10250 12.8 55.0 015 3 1 10.0 5.5 | 13.0 55.4 050 5 2 9.7 5.3
10000 13.6 56.5 020 3 1 10.5 5.8 | 13.8 56.8 055 5 3 9.9 5.4
9750 14.4 57.9 025 3 2 8.9 4.9 | 14.5 58.1 055 5 3 9.6 5.3
9500 15.1 59.2 025 3 2 14.2 7.8 | 15.2 59.4 055 6 3 10.3 5.6
9250 16.6 61.9 030 3 2 27.9 15.3 | 16.0 60.8 055 5 3 12.0 6.6
9000 18.3 64.9 035 3 2 6.8 3.7 | 16.8 62.2 060 5 3 9.1 5.0
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