Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
713
UXUS97 KPUB 181212
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0612 MDT Sunday, May 18, 2025
This forecast is for Villa Grove, CO for Sunday, May 18, 2025:
If the trigger temperature of 48.8 F/9.4 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 766 ft/min (3.9 m/s)
Maximum height of thermals.................. 21039 ft MSL (12073 ft AGL)
Forecast maximum temperature................... 61.0 F/16.6 C
Time of trigger temperature.................... 0815 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 17822 ft MSL (8856 ft AGL)
Thermal soaring outlook for Monday 05/19....... Fair
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:49:35 / 20:10:31 MDT
Total possible sunshine........... 14 hr 20 min 55 sec (860 min 55 sec)
Altitude of sun at 13:00:03 MDT... 71.47 degrees
Upper air data from numerical model forecast valid on 05/18/2025 at 0600 MDT
Freezing level.................. 12018 ft MSL (3052 ft AGL)
Convective condensation level... 19483 ft MSL (10517 ft AGL)
Lifted condensation level....... 20322 ft MSL (11356 ft AGL)
Lifted index.................... +0.1
K index......................... +1.1
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 -56.1 -69.0 235 35 18 -0.4 -0.2 M M M M M
45000 -56.7 -70.1 230 43 22 -0.3 -0.2 M M M M M
40000 -57.1 -70.8 225 52 27 -0.3 -0.2 M M M M M
38000 -55.3 -67.5 225 58 30 4.8 2.6 M M M M M
36000 -52.4 -62.3 220 66 34 4.8 2.6 M M M M M
34000 -49.3 -56.7 215 72 37 5.8 3.2 M M M M M
32000 -45.8 -50.4 215 69 35 5.8 3.2 M M M M M
30000 -42.0 -43.6 210 66 34 8.0 4.4 22.4 72.3 4.9 M M
29000 -39.6 -39.3 215 64 33 8.2 4.5 21.7 71.0 4.4 M M
28000 -37.1 -34.8 215 62 32 8.2 4.5 21.1 70.0 4.0 M M
27000 -34.0 -29.2 215 60 31 8.8 4.9 20.5 68.9 3.5 M M
26000 -31.4 -24.5 215 56 29 8.8 4.8 20.1 68.1 3.2 M M
25000 -28.8 -19.8 215 51 26 8.8 4.9 19.8 67.6 3.0 M M
24000 -26.2 -15.2 210 47 24 7.5 4.1 19.5 67.1 2.8 M M
23000 -24.2 -11.6 210 47 24 6.6 3.6 18.3 65.0 1.8 M M
22000 -22.3 -8.1 210 47 24 6.6 3.6 17.2 63.0 0.8 M M
21000 -20.3 -4.5 205 47 24 6.5 3.6 16.2 61.2 -0.0 1162 5.9
20000 -18.4 -1.1 205 46 24 6.5 3.6 15.0 59.1 -1.1 1075 5.5
19500 -17.4 0.7 200 46 24 6.5 3.6 14.5 58.1 -1.6 1031 5.2
19000 -16.4 2.5 200 46 24 6.5 3.6 14.0 57.2 -2.1 987 5.0
18500 -15.4 4.3 200 45 23 7.2 4.0 13.5 56.3 -2.5 943 4.8
18000 -14.3 6.3 200 45 23 7.7 4.2 13.1 55.7 -2.8 894 4.5
17500 -13.1 8.4 200 45 23 7.8 4.3 12.8 55.1 -3.2 845 4.3
17000 -12.0 10.4 200 44 23 7.9 4.3 12.5 54.5 -3.5 795 4.0
16500 -10.8 12.6 200 42 22 7.9 4.3 12.2 54.0 -3.8 745 3.8
16000 -9.7 14.5 200 40 21 7.5 4.1 11.9 53.4 -4.1 696 3.5
15500 -8.6 16.5 205 38 19 7.4 4.0 11.5 52.7 -4.5 648 3.3
15000 -7.4 18.7 210 35 18 7.9 4.3 11.1 52.0 -4.9 600 3.0
14500 -6.2 20.8 210 32 17 9.0 5.0 10.9 51.7 -5.1 546 2.8
14000 -5.2 22.6 215 28 15 4.7 2.6 10.4 50.8 -5.5 502 2.5
13500 -3.5 25.7 225 24 12 8.9 4.9 9.9 49.9 -6.1 429 2.2
13000 -2.4 27.7 230 22 11 7.3 4.0 9.5 49.2 -6.6 383 1.9
12500 -1.1 30.0 235 22 11 9.1 5.0 9.5 49.0 -6.7 328 1.7
12000 0.3 32.5 240 23 12 8.5 4.7 9.4 49.0 -6.8 272 1.4
11750 0.9 33.6 240 22 11 8.8 4.8 9.3 48.7 -7.0 247 1.3
11500 1.6 34.9 240 22 11 10.0 5.5 9.3 48.7 -7.0 217 1.1
11250 2.3 36.1 240 22 11 10.1 5.5 9.3 48.7 -7.0 188 1.0
11000 3.1 37.6 240 22 11 8.8 4.8 9.3 48.8 -7.0 159 0.8
10750 3.6 38.5 240 22 11 7.4 4.1 9.2 48.5 -7.2 134 0.7
10500 4.2 39.6 240 22 11 7.1 3.9 9.0 48.2 -7.4 110 0.6
10250 4.8 40.6 235 22 11 9.0 5.0 8.8 47.9 -7.6 86 0.4
10000 5.3 41.5 235 22 11 1.6 0.9 8.6 47.6 -7.8 62 0.3
9750 4.9 40.8 235 20 10 -7.7 -4.2 7.5 45.6 -8.9 66 0.3
9500 4.5 40.1 230 18 9 -1.1 -0.6 6.4 43.5 -10.1 72 0.4
9250 4.3 39.7 225 15 8 -10.5 -5.8 5.5 41.9 -11.1 70 0.4
9000 0.7 33.3 215 7 3 -99.0 -54.3 1.2 34.2 -15.4 171 0.9
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 * * * * * *
05/18/2025 at 0900 MDT | 05/18/2025 at 1200 MDT
|
CAPE... 0.0 LI... +3.1 | CAPE... +129.7 LI... +0.8
CINH... 0.0 K Index... +7.8 | CINH... -2.8 K Index... +13.4
|
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 -55.4 -67.7 230 32 17 0.2 0.1 | -54.2 -65.6 230 35 18 1.3 0.7
45000 -55.2 -67.4 225 41 21 -0.1 -0.0 | -52.2 -62.0 220 42 22 0.7 0.4
40000 -55.4 -67.7 220 68 35 -0.2 -0.1 | -51.6 -60.9 220 61 31 0.3 0.2
38000 -54.2 -65.6 220 72 37 3.3 1.8 | -50.8 -59.4 220 67 34 2.1 1.2
36000 -52.2 -62.0 215 74 38 3.3 1.8 | -49.5 -57.1 215 72 37 2.1 1.2
34000 -49.8 -57.6 210 76 39 7.1 3.9 | -48.1 -54.6 215 77 39 4.9 2.7
32000 -45.6 -50.1 210 74 38 7.0 3.8 | -45.3 -49.5 215 73 37 4.6 2.6
30000 -41.4 -42.5 210 72 37 6.8 3.7 | -42.5 -44.5 215 69 35 5.7 3.1
29000 -39.4 -38.9 210 70 36 6.8 3.7 | -40.7 -41.3 215 65 33 5.7 3.1
28000 -36.8 -34.2 210 69 35 6.8 3.7 | -38.6 -37.5 210 59 31 5.7 3.1
27000 -34.8 -30.6 210 67 35 7.0 3.8 | -36.9 -34.4 210 55 28 5.8 3.2
26000 -32.7 -26.9 210 63 32 7.1 3.9 | -35.1 -31.2 210 53 27 6.0 3.3
25000 -30.6 -23.1 210 59 30 7.1 3.9 | -33.4 -28.1 210 51 26 6.0 3.3
24000 -28.5 -19.3 210 55 28 7.6 4.2 | -31.6 -24.9 210 49 25 6.0 3.3
23000 -26.0 -14.8 210 50 26 8.6 4.7 | -29.2 -20.6 205 47 24 8.6 4.7
22000 -23.4 -10.1 205 46 24 8.6 4.7 | -26.6 -15.9 200 44 23 8.6 4.7
21000 -20.9 -5.6 205 42 21 8.4 4.6 | -24.0 -11.2 195 42 22 9.0 4.9
20000 -18.4 -1.1 200 42 21 8.4 4.6 | -21.3 -6.3 195 38 19 9.4 5.2
19500 -17.2 1.0 200 42 21 8.4 4.6 | -19.9 -3.8 195 36 18 9.4 5.2
19000 -16.0 3.2 195 42 21 8.3 4.6 | -18.5 -1.3 195 34 17 9.4 5.1
18500 -14.7 5.5 195 42 22 7.0 3.9 | -17.1 1.2 190 32 16 8.9 4.9
18000 -14.0 6.8 195 43 22 4.5 2.4 | -16.0 3.2 195 32 17 6.7 3.7
17500 -13.3 8.1 195 45 23 4.3 2.4 | -15.0 5.0 200 34 18 6.9 3.8
17000 -12.6 9.3 195 46 24 5.8 3.2 | -14.0 6.8 200 36 19 6.3 3.5
16500 -11.7 10.9 195 46 24 5.8 3.2 | -13.0 8.6 205 38 19 6.3 3.5
16000 -10.8 12.6 195 46 24 6.4 3.5 | -12.1 10.2 210 39 20 6.7 3.7
15500 -9.8 14.4 200 46 23 6.9 3.8 | -11.1 12.0 210 38 20 7.3 4.0
15000 -8.7 16.3 200 45 23 7.3 4.0 | -10.0 14.0 210 36 19 7.4 4.1
14500 -6.9 19.6 205 43 22 6.7 3.7 | -8.0 17.6 210 33 17 9.1 5.0
14000 -6.2 20.8 205 43 22 6.3 3.5 | -6.8 19.8 210 31 16 9.5 5.2
13500 -5.1 22.8 210 39 20 8.0 4.4 | -5.2 22.6 210 31 16 10.9 6.0
13000 -4.1 24.6 210 34 18 5.3 2.9 | -3.9 25.0 210 30 16 7.9 4.4
12500 -3.1 26.4 215 34 17 7.0 3.8 | -2.4 27.7 210 30 15 10.2 5.6
12000 -2.1 28.2 220 34 18 8.0 4.4 | -0.9 30.4 210 30 15 10.4 5.7
11750 -1.5 29.3 220 32 17 8.5 4.6 | -0.1 31.8 210 30 15 10.5 5.7
11500 -0.9 30.4 225 31 16 7.5 4.1 | 0.6 33.1 210 29 15 10.1 5.6
11250 -0.3 31.5 225 29 15 7.7 4.2 | 1.4 34.5 210 29 15 10.4 5.7
11000 0.2 32.4 225 27 14 8.0 4.4 | 2.1 35.8 210 29 15 9.8 5.4
10750 0.9 33.6 230 25 13 9.5 5.2 | 2.9 37.2 210 29 15 10.0 5.5
10500 1.6 34.9 230 23 12 10.2 5.6 | 3.6 38.5 210 28 15 10.7 5.9
10250 2.4 36.3 230 22 11 9.9 5.5 | 4.4 39.9 210 28 14 10.5 5.7
10000 3.1 37.6 225 20 10 10.2 5.6 | 5.2 41.4 210 28 14 10.6 5.8
9750 3.9 39.0 225 19 10 11.7 6.4 | 6.1 43.0 210 27 14 13.5 7.4
9500 4.9 40.8 225 18 9 16.8 9.2 | 7.4 45.3 210 26 13 22.3 12.2
9250 6.4 43.5 225 15 8 22.7 12.4 | 9.4 48.9 210 23 12 30.4 16.7
9000 7.9 46.2 225 13 7 12.9 7.1 | 11.4 52.5 210 20 10 17.8 9.8
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
05/18/2025 at 1500 MDT | 05/18/2025 at 1800 MDT
|
CAPE... +187.9 LI... -1.2 | CAPE... +179.0 LI... -0.4
CINH... 0.0 K Index... +12.2 | CINH... -5.2 K Index... +19.1
|
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 -53.9 -65.0 240 29 15 1.6 0.9 | -53.8 -64.8 240 30 15 0.6 0.3
45000 -51.5 -60.7 230 36 18 0.9 0.5 | -52.9 -63.2 240 36 18 1.0 0.5
40000 -50.8 -59.4 235 50 26 0.5 0.3 | -51.1 -60.0 240 47 24 1.2 0.6
38000 -49.9 -57.8 235 56 29 2.4 1.3 | -50.1 -58.2 240 50 26 1.9 1.0
36000 -48.4 -55.1 235 61 32 2.4 1.3 | -49.0 -56.2 245 53 27 1.9 1.0
34000 -46.9 -52.4 235 66 34 3.2 1.8 | -47.8 -54.0 245 54 28 2.7 1.5
32000 -45.0 -49.0 240 59 30 3.2 1.8 | -46.3 -51.3 250 46 24 2.6 1.4
30000 -43.0 -45.4 240 52 27 5.7 3.1 | -44.4 -47.9 255 39 20 7.0 3.8
29000 -40.7 -41.3 245 45 23 6.1 3.3 | -41.8 -43.2 260 33 17 7.0 3.8
28000 -38.9 -38.0 245 40 21 6.1 3.3 | -39.7 -39.5 265 28 14 7.0 3.8
27000 -37.1 -34.8 250 35 18 6.4 3.5 | -37.7 -35.9 270 23 12 7.8 4.3
26000 -34.9 -30.8 250 32 16 7.4 4.1 | -35.0 -31.0 270 20 10 9.0 5.0
25000 -32.7 -26.9 255 29 15 7.4 4.1 | -32.3 -26.1 270 17 9 9.1 5.0
24000 -30.5 -22.9 260 26 13 7.5 4.1 | -29.6 -21.3 265 14 7 9.0 4.9
23000 -28.3 -18.9 260 24 12 7.1 3.9 | -27.1 -16.8 255 16 8 8.3 4.6
22000 -26.2 -15.2 260 23 12 7.1 3.9 | -24.6 -12.3 250 18 9 8.3 4.6
21000 -24.1 -11.4 260 22 11 7.3 4.0 | -22.1 -7.8 245 21 11 8.0 4.4
20000 -21.8 -7.2 260 20 11 7.6 4.2 | -19.9 -3.8 245 25 13 7.7 4.2
19500 -20.7 -5.3 255 20 10 7.6 4.2 | -18.7 -1.7 245 27 14 7.7 4.2
19000 -19.6 -3.3 255 19 10 7.6 4.2 | -17.6 0.3 250 29 15 7.7 4.2
18500 -18.4 -1.1 255 18 9 7.7 4.2 | -16.5 2.3 250 31 16 7.5 4.1
18000 -17.3 0.9 250 19 10 8.2 4.5 | -15.4 4.3 250 33 17 6.7 3.7
17500 -16.1 3.0 245 21 11 8.1 4.5 | -14.4 6.1 250 34 18 6.7 3.7
17000 -14.8 5.4 245 23 12 8.5 4.6 | -13.4 7.9 250 35 18 7.5 4.1
16500 -13.6 7.5 240 25 13 8.5 4.7 | -12.3 9.9 250 36 19 7.6 4.2
16000 -12.4 9.7 235 27 14 8.6 4.7 | -11.2 11.8 255 37 19 7.5 4.1
15500 -11.1 12.0 230 28 14 8.6 4.7 | -10.1 13.8 255 38 20 7.3 4.0
15000 -9.9 14.2 230 29 15 8.6 4.7 | -9.0 15.8 255 39 20 7.3 4.0
14500 -8.6 16.5 225 29 15 9.1 5.0 | -7.4 18.7 255 37 19 7.9 4.3
14000 -6.3 20.7 225 29 15 10.7 5.9 | -6.2 20.8 255 34 17 8.5 4.7
13500 -4.7 23.5 225 29 15 11.3 6.2 | -4.9 23.2 250 31 16 9.7 5.3
13000 -3.3 26.1 225 29 15 7.4 4.1 | -3.6 25.5 250 29 15 7.8 4.3
12500 -1.9 28.6 220 29 15 10.2 5.6 | -2.3 27.9 245 28 14 9.5 5.2
12000 -0.4 31.3 220 29 15 9.9 5.4 | -0.9 30.4 245 27 14 9.8 5.4
11750 0.3 32.5 220 29 15 10.0 5.5 | -0.1 31.8 245 27 14 10.0 5.5
11500 1.1 34.0 220 28 15 10.2 5.6 | 0.6 33.1 245 27 14 9.7 5.3
11250 1.8 35.2 220 28 15 10.4 5.7 | 1.3 34.3 245 26 13 9.7 5.3
11000 2.6 36.7 220 28 14 9.4 5.2 | 2.1 35.8 245 26 13 10.0 5.5
10750 3.3 37.9 220 28 14 9.8 5.4 | 2.8 37.0 245 25 13 10.2 5.6
10500 4.1 39.4 220 28 14 11.0 6.1 | 3.6 38.5 245 25 13 10.2 5.6
10250 4.9 40.8 220 27 14 10.8 5.9 | 4.3 39.7 245 24 13 10.2 5.6
10000 5.7 42.3 220 27 14 10.6 5.8 | 5.1 41.2 245 24 12 10.2 5.6
9750 6.5 43.7 220 27 14 12.9 7.1 | 5.9 42.6 245 23 12 11.7 6.4
9500 7.8 46.0 220 25 13 21.6 11.9 | 6.9 44.4 245 22 11 16.1 8.8
9250 9.7 49.5 220 22 11 30.1 16.5 | 8.3 46.9 245 19 10 20.1 11.0
9000 11.7 53.1 215 19 10 16.9 9.3 | 9.6 49.3 245 16 8 14.0 7.7
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