Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
278
UXUS97 KPUB 201234
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0634 MDT Sunday, April 20, 2025
This forecast is for Villa Grove, CO for Sunday, April 20, 2025:
If the trigger temperature of 36.3 F/2.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1057 ft/min (5.4 m/s)
Maximum height of thermals.................. 20859 ft MSL (11872 ft AGL)
Forecast maximum temperature................... 54.0 F/12.7 C
Time of trigger temperature.................... 0945 MDT
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................. 17888 ft MSL (8901 ft AGL)
Thermal soaring outlook for Monday 04/21....... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:20:01 / 19:44:43 MDT
Total possible sunshine........... 13 hr 24 min 43 sec (804 min 43 sec)
Altitude of sun at 13:02:22 MDT... 63.53 degrees
Upper air data from numerical model forecast valid on 04/20/2025 at 0600 MDT
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 16600 ft MSL (7613 ft AGL)
Lifted condensation level....... 18667 ft MSL (9680 ft AGL)
Lifted index.................... +1.9
K index......................... -22.8
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 -58.7 -73.7 265 29 15 0.6 0.4 M M M M M
45000 -57.7 -71.9 265 39 20 0.5 0.3 M M M M M
40000 -57.0 -70.6 285 44 23 0.4 0.2 M M M M M
38000 -56.0 -68.8 295 44 22 3.2 1.7 M M M M M
36000 -54.1 -65.4 300 40 20 3.2 1.7 M M M M M
34000 -51.9 -61.4 305 36 19 7.5 4.1 M M M M M
32000 -47.5 -53.5 315 36 18 7.3 4.0 M M M M M
30000 -42.6 -44.7 325 35 18 7.3 4.0 22.0 71.6 7.7 M M
29000 -40.4 -40.7 325 35 18 7.3 4.0 21.0 69.8 6.9 M M
28000 -38.2 -36.8 330 36 18 7.3 4.0 20.1 68.2 6.3 M M
27000 -36.0 -32.8 335 36 18 7.2 3.9 19.4 66.9 5.8 M M
26000 -33.9 -29.0 335 38 19 6.9 3.8 18.2 64.8 4.9 M M
25000 -31.9 -25.4 335 39 20 6.9 3.8 17.2 62.9 4.1 M M
24000 -29.8 -21.6 335 41 21 6.9 3.8 16.3 61.3 3.4 M M
23000 -27.9 -18.2 335 40 20 6.0 3.3 14.9 58.9 2.3 M M
22000 -26.1 -15.0 335 38 19 6.0 3.3 13.6 56.5 1.2 M M
21000 -24.3 -11.7 335 36 18 6.3 3.4 12.5 54.4 0.2 M M
20000 -22.4 -8.3 335 32 17 6.5 3.6 11.3 52.3 -0.9 985 5.0
19500 -21.4 -6.5 330 30 16 6.5 3.6 10.7 51.3 -1.4 941 4.8
19000 -20.4 -4.7 330 29 15 6.5 3.6 10.2 50.3 -1.8 897 4.6
18500 -19.5 -3.1 325 27 14 6.5 3.6 9.7 49.4 -2.3 853 4.3
18000 -18.5 -1.3 325 25 13 6.5 3.5 9.1 48.5 -2.8 809 4.1
17500 -17.5 0.5 320 23 12 6.5 3.6 8.6 47.5 -3.3 765 3.9
17000 -16.6 2.1 315 21 11 6.0 3.3 8.0 46.5 -3.8 722 3.7
16500 -15.7 3.7 315 19 10 6.0 3.3 7.4 45.3 -4.4 680 3.5
16000 -14.8 5.4 310 18 9 5.8 3.2 6.8 44.2 -5.0 639 3.2
15500 -13.5 7.7 310 16 8 5.6 3.1 5.8 42.4 -6.0 579 2.9
15000 -12.7 9.1 310 15 8 6.0 3.3 5.2 41.3 -6.7 539 2.7
14500 -11.8 10.8 315 15 8 6.0 3.3 4.6 40.3 -7.3 497 2.5
14000 -11.2 11.8 320 15 8 4.1 2.3 3.7 38.6 -8.2 465 2.4
13500 -10.4 13.3 325 15 8 5.6 3.1 3.1 37.5 -8.9 425 2.2
13000 -9.5 14.9 330 15 7 5.7 3.1 2.5 36.5 -9.5 384 2.0
12500 -8.8 16.2 335 14 7 5.1 2.8 1.7 35.1 -10.3 349 1.8
12000 -8.1 17.4 335 14 7 6.6 3.6 1.0 33.8 -11.2 313 1.6
11750 -7.6 18.3 335 14 7 7.2 3.9 0.8 33.5 -11.4 289 1.5
11500 -7.1 19.2 335 14 7 5.7 3.1 0.5 33.0 -11.7 269 1.4
11250 -6.7 19.9 335 14 7 5.9 3.3 0.3 32.5 -12.0 249 1.3
11000 -6.3 20.7 335 15 8 6.9 3.8 -0.0 32.0 -12.4 228 1.2
10750 -5.7 21.7 330 14 7 7.3 4.0 -0.2 31.7 -12.6 205 1.0
10500 -5.3 22.5 325 14 7 6.2 3.4 -0.4 31.2 -12.9 184 0.9
10250 -4.8 23.4 320 13 7 6.2 3.4 -0.7 30.7 -13.2 163 0.8
10000 -4.4 24.1 315 13 7 5.6 3.1 -1.0 30.2 -13.6 143 0.7
9750 -4.0 24.8 315 12 6 4.8 2.6 -1.3 29.6 -14.0 125 0.6
9500 -3.8 25.2 310 11 6 2.9 1.6 -1.8 28.8 -14.5 109 0.6
9250 -3.8 25.2 305 9 5 -6.1 -3.4 -2.5 27.4 -15.3 103 0.5
9000 -5.2 22.6 285 4 2 -35.3 -19.4 -4.6 23.6 -17.4 137 0.7
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 * * * * * *
04/20/2025 at 0900 MDT | 04/20/2025 at 1200 MDT
|
CAPE... 0.0 LI... +4.7 | CAPE... +6.2 LI... +3.1
CINH... 0.0 K Index... -13.5 | CINH... 0.0 K Index... +5.3
|
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 -58.4 -73.1 270 31 16 0.1 0.1 | -59.3 -74.7 270 31 16 0.9 0.5
45000 -58.2 -72.8 275 47 24 0.4 0.2 | -57.9 -72.2 280 48 25 0.8 0.5
40000 -57.2 -71.0 280 46 24 0.7 0.4 | -56.7 -70.1 280 57 30 0.8 0.5
38000 -56.3 -69.3 280 43 22 2.5 1.4 | -55.6 -68.1 280 56 29 3.0 1.6
36000 -54.8 -66.6 280 35 18 2.5 1.4 | -53.8 -64.8 280 49 25 3.0 1.6
34000 -53.0 -63.4 280 28 14 7.1 3.9 | -51.9 -61.4 285 42 22 5.6 3.0
32000 -49.0 -56.2 280 27 14 6.7 3.7 | -48.1 -54.6 280 38 19 5.5 3.0
30000 -44.2 -47.6 280 27 14 8.4 4.6 | -44.6 -48.3 280 34 17 7.2 4.0
29000 -41.7 -43.1 285 28 14 8.4 4.6 | -42.4 -44.3 280 32 16 7.3 4.0
28000 -39.1 -38.4 290 29 15 8.4 4.6 | -40.2 -40.4 280 30 15 7.3 4.0
27000 -36.6 -33.9 290 30 15 8.1 4.5 | -38.0 -36.4 280 28 14 7.7 4.2
26000 -34.3 -29.7 295 30 15 7.9 4.3 | -35.6 -32.1 285 27 14 8.1 4.5
25000 -31.9 -25.4 300 30 15 7.9 4.3 | -33.2 -27.8 285 26 13 8.1 4.5
24000 -29.5 -21.1 305 30 15 7.7 4.3 | -30.8 -23.4 290 25 13 8.1 4.4
23000 -27.3 -17.1 310 28 15 7.3 4.0 | -28.4 -19.1 290 25 13 8.0 4.4
22000 -25.1 -13.2 315 27 14 7.3 4.0 | -26.0 -14.8 290 24 13 8.0 4.4
21000 -22.9 -9.2 325 25 13 7.2 4.0 | -23.6 -10.5 290 24 12 7.7 4.2
20000 -20.8 -5.4 325 25 13 7.2 3.9 | -21.3 -6.3 300 22 12 7.6 4.2
19500 -19.7 -3.5 325 25 13 7.2 3.9 | -20.2 -4.4 300 22 11 7.6 4.2
19000 -18.6 -1.5 325 24 12 7.1 3.9 | -19.1 -2.4 305 22 11 7.6 4.1
18500 -17.6 0.3 325 24 12 6.1 3.4 | -17.9 -0.2 310 21 11 7.0 3.9
18000 -16.8 1.8 325 23 12 4.7 2.6 | -17.0 1.4 315 21 11 6.4 3.5
17500 -16.2 2.8 325 23 12 4.7 2.6 | -16.0 3.2 320 21 11 6.5 3.5
17000 -15.5 4.1 320 21 11 3.7 2.0 | -15.1 4.8 320 21 11 5.3 2.9
16500 -15.0 5.0 320 20 10 3.8 2.1 | -14.3 6.3 320 21 11 5.4 3.0
16000 -14.4 6.1 320 18 9 4.6 2.5 | -13.2 8.2 325 20 10 4.2 2.3
15500 -13.7 7.3 325 17 9 4.9 2.7 | -12.6 9.3 325 19 10 4.2 2.3
15000 -13.0 8.6 330 17 9 5.4 2.9 | -12.0 10.4 325 18 9 4.9 2.7
14500 -11.6 11.1 330 16 8 5.8 3.2 | -11.3 11.7 325 16 8 4.7 2.6
14000 -11.0 12.2 335 16 8 4.4 2.4 | -10.5 13.1 320 14 7 7.9 4.3
13500 -10.2 13.6 335 17 9 5.3 2.9 | -9.2 15.4 315 12 6 8.7 4.8
13000 -9.4 15.1 330 17 9 6.2 3.4 | -7.9 17.8 310 11 6 9.3 5.1
12500 -8.5 16.7 330 17 9 6.1 3.3 | -6.5 20.3 310 11 5 9.6 5.3
12000 -7.6 18.3 325 18 9 5.2 2.9 | -5.1 22.8 310 10 5 10.0 5.5
11750 -7.2 19.0 325 17 9 5.6 3.1 | -4.3 24.3 310 10 5 10.4 5.7
11500 -6.8 19.8 325 17 9 6.5 3.5 | -3.5 25.7 310 10 5 10.4 5.7
11250 -6.3 20.7 320 16 8 6.4 3.5 | -2.7 27.1 310 10 5 10.4 5.7
11000 -5.9 21.4 320 15 8 6.8 3.7 | -2.0 28.4 310 10 5 10.2 5.6
10750 -5.4 22.3 315 14 7 8.0 4.4 | -1.2 29.8 310 9 5 10.0 5.5
10500 -4.7 23.5 310 12 6 9.3 5.1 | -0.5 31.1 310 9 5 9.9 5.4
10250 -4.0 24.8 305 11 5 9.7 5.3 | 0.3 32.5 310 9 5 10.2 5.6
10000 -3.3 26.1 300 9 5 10.0 5.5 | 1.1 34.0 310 9 5 11.4 6.2
9750 -2.5 27.5 295 9 5 10.6 5.8 | 2.0 35.6 310 9 4 12.4 6.8
9500 -1.8 28.8 290 8 4 10.3 5.6 | 2.9 37.2 310 8 4 9.8 5.4
9250 -0.9 30.4 290 8 4 15.4 8.4 | 3.7 38.7 310 8 4 16.3 9.0
9000 1.2 34.2 290 7 4 49.5 27.2 | 6.8 44.2 310 8 4 82.8 45.4
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
04/20/2025 at 1500 MDT | 04/20/2025 at 1800 MDT
|
CAPE... +111.2 LI... -0.5 | CAPE... +47.5 LI... -0.2
CINH... -0.5 K Index... +15.8 | CINH... -0.0 K Index... +2.4
|
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 -60.0 -76.0 265 38 20 1.2 0.6 | -61.7 -79.1 265 40 20 0.7 0.4
45000 -58.1 -72.6 280 48 25 0.9 0.5 | -60.6 -77.1 275 56 29 1.6 0.9
40000 -56.9 -70.4 285 60 31 0.8 0.5 | -57.7 -71.9 285 64 33 1.9 1.0
38000 -55.7 -68.3 285 61 32 3.2 1.8 | -55.8 -68.4 290 65 34 4.2 2.3
36000 -53.8 -64.8 290 59 30 3.2 1.8 | -53.3 -63.9 290 63 33 4.2 2.3
34000 -51.6 -60.9 290 56 29 6.8 3.7 | -50.5 -58.9 290 61 31 6.1 3.4
32000 -47.2 -53.0 290 51 26 6.4 3.5 | -46.4 -51.5 295 56 29 6.0 3.3
30000 -43.3 -45.9 290 46 24 7.0 3.8 | -42.6 -44.7 295 52 27 7.3 4.0
29000 -41.2 -42.2 290 43 22 7.0 3.8 | -40.4 -40.7 295 49 25 7.3 4.0
28000 -39.1 -38.4 290 40 20 7.0 3.8 | -38.2 -36.8 300 46 24 7.3 4.0
27000 -37.0 -34.6 290 37 19 6.7 3.7 | -36.0 -32.8 300 43 22 6.5 3.6
26000 -35.1 -31.2 290 33 17 6.5 3.6 | -34.2 -29.6 300 40 21 6.3 3.5
25000 -33.1 -27.6 285 30 16 6.6 3.6 | -32.3 -26.1 295 37 19 6.3 3.5
24000 -31.1 -24.0 280 27 14 6.9 3.8 | -30.4 -22.7 295 34 18 6.9 3.8
23000 -28.9 -20.0 285 27 14 7.6 4.2 | -28.1 -18.6 295 33 17 7.6 4.2
22000 -26.6 -15.9 285 27 14 7.6 4.2 | -25.8 -14.4 295 31 16 7.6 4.2
21000 -24.3 -11.7 290 27 14 7.8 4.3 | -23.5 -10.3 295 29 15 7.1 3.9
20000 -22.0 -7.6 290 26 14 7.8 4.3 | -21.4 -6.5 290 26 14 7.1 3.9
19500 -20.9 -5.6 290 26 13 7.8 4.3 | -20.4 -4.7 290 25 13 7.1 3.9
19000 -19.7 -3.5 295 25 13 7.9 4.3 | -19.3 -2.7 285 24 12 7.1 3.9
18500 -18.5 -1.3 295 25 13 7.4 4.1 | -18.3 -0.9 285 23 12 7.4 4.0
18000 -17.5 0.5 295 23 12 7.2 3.9 | -17.2 1.0 280 21 11 7.4 4.1
17500 -16.4 2.5 295 21 11 7.2 3.9 | -16.1 3.0 275 18 9 7.5 4.1
17000 -15.4 4.3 295 19 10 7.1 3.9 | -15.0 5.0 270 17 9 7.6 4.2
16500 -14.4 6.1 295 17 9 7.1 3.9 | -13.9 7.0 270 17 9 7.6 4.2
16000 -13.3 8.1 290 15 8 7.3 4.0 | -12.7 9.1 270 17 9 8.3 4.5
15500 -11.7 10.9 295 14 7 7.1 3.9 | -11.5 11.3 280 18 9 8.3 4.5
15000 -10.4 13.3 290 14 7 10.6 5.8 | -9.6 14.7 285 18 9 8.9 4.9
14500 -8.9 16.0 290 13 7 8.4 4.6 | -8.3 17.1 290 18 9 7.2 4.0
14000 -7.7 18.1 290 13 7 9.5 5.2 | -7.2 19.0 290 17 9 9.4 5.1
13500 -6.3 20.7 290 13 7 9.7 5.3 | -5.9 21.4 290 17 9 9.2 5.0
13000 -4.8 23.4 290 13 7 9.8 5.4 | -4.5 23.9 290 17 9 9.6 5.3
12500 -3.4 25.9 290 13 7 10.1 5.5 | -3.1 26.4 295 17 9 9.8 5.4
12000 -2.0 28.4 290 13 6 8.6 4.7 | -1.7 28.9 295 17 9 8.8 4.8
11750 -1.3 29.7 290 13 6 10.1 5.5 | -1.0 30.2 295 17 9 10.0 5.5
11500 -0.5 31.1 290 12 6 10.8 5.9 | -0.3 31.5 295 17 9 10.4 5.7
11250 0.3 32.5 290 12 6 10.5 5.8 | 0.5 32.9 295 17 9 10.1 5.6
11000 1.1 34.0 290 12 6 10.3 5.6 | 1.2 34.2 295 17 9 9.3 5.1
10750 1.9 35.4 290 12 6 10.1 5.5 | 1.9 35.4 295 17 9 10.0 5.5
10500 2.6 36.7 295 12 6 10.0 5.5 | 2.7 36.9 295 16 8 11.2 6.2
10250 3.4 38.1 295 12 6 10.3 5.6 | 3.6 38.5 295 16 8 10.7 5.9
10000 4.2 39.6 295 12 6 11.1 6.1 | 4.3 39.7 295 16 8 9.8 5.4
9750 5.0 41.0 295 11 6 12.1 6.6 | 5.1 41.2 295 15 8 10.0 5.5
9500 5.9 42.6 295 11 6 11.2 6.2 | 5.9 42.6 295 15 8 11.1 6.1
9250 6.9 44.4 295 10 5 18.0 9.9 | 6.8 44.2 295 14 7 15.6 8.6
9000 9.7 49.5 290 10 5 69.3 38.0 | 8.5 47.3 290 12 6 35.0 19.2
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