Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
048
UXUS97 KGJT 121307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Wednesday, March 12, 2025
This forecast is for Wednesday, March 12, 2025:
If the trigger temperature of 56.3 F/13.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1003 ft/min (5.1 m/s)
Maximum height of thermals.................. 15896 ft MSL (11057 ft AGL)
Forecast maximum temperature................... 63.0 F/17.7 C
Time of trigger temperature.................... 1245 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................. 10675 ft MSL (5836 ft AGL)
Thermal soaring outlook for Thursday 03/13..... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:29:09 / 19:18:15 MDT
Total possible sunshine........... 11 hr 49 min 6 sec (709 min 6 sec)
Altitude of sun at 13:23:42 MDT... 47.54 degrees
Upper air data from rawinsonde observation taken on 03/12/2025 at 0600 MDT
Freezing level.................. 9403 ft MSL (4564 ft AGL)
Convective condensation level... 17564 ft MSL (12725 ft AGL)
Lifted condensation level....... 16804 ft MSL (11965 ft AGL)
Lifted index.................... +1.9
K index......................... +11.8
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 -54.2 -65.6 280 35 18 -1.3 -0.7 112.4 234.3 54.0 M M
45000 -55.4 -67.7 250 26 13 -3.4 -1.9 85.5 185.9 41.5 M M
40000 -51.9 -61.4 280 29 15 4.5 2.5 67.8 154.1 32.8 M M
38000 -53.4 -64.1 280 18 9 -3.7 -2.0 56.6 133.9 26.3 M M
36000 -54.0 -65.2 265 16 8 2.8 1.6 47.0 116.6 20.4 M M
34000 -55.0 -67.0 225 11 6 -3.3 -1.8 36.1 97.0 13.3 M M
32000 -53.8 -64.8 255 9 5 3.6 2.0 29.6 85.2 8.9 M M
30000 -51.5 -60.7 205 12 6 6.0 3.3 24.8 76.6 5.6 M M
29000 -48.8 -55.8 220 9 5 9.5 5.2 24.4 76.0 5.4 M M
28000 -46.0 -50.8 225 9 5 9.2 5.1 24.3 75.7 5.4 M M
27000 -43.2 -45.8 240 9 5 9.3 5.1 24.1 75.3 5.3 M M
26000 -40.4 -40.7 245 12 6 9.1 5.0 23.9 75.0 5.2 M M
25000 -37.6 -35.7 235 12 6 10.1 5.6 23.8 74.8 5.2 M M
24000 -34.8 -30.6 240 16 8 8.8 4.8 23.6 74.5 5.1 M M
23000 -32.3 -26.1 255 15 8 8.5 4.6 23.1 73.5 4.7 M M
22000 -29.8 -21.6 275 17 9 8.3 4.6 22.6 72.7 4.4 M M
21000 -27.1 -16.8 270 16 8 9.3 5.1 22.3 72.2 4.2 M M
20000 -24.3 -11.7 255 15 8 8.0 4.4 22.2 71.9 4.1 M M
19500 -23.5 -10.3 240 16 8 4.6 2.5 21.5 70.6 3.5 M M
19000 -21.8 -7.2 230 13 7 8.8 4.8 20.9 69.6 3.1 M M
18500 -20.4 -4.7 240 15 8 9.9 5.4 20.7 69.3 3.0 M M
18000 -19.3 -2.7 240 18 9 4.8 2.6 20.4 68.7 2.7 M M
17500 -18.5 -1.3 250 18 9 5.4 3.0 19.6 67.4 2.0 M M
17000 -17.7 0.1 240 19 10 5.5 3.0 18.9 66.0 1.4 M M
16500 -16.9 1.6 235 19 10 5.5 3.0 18.2 64.7 0.7 M M
16000 -16.1 3.0 245 16 8 5.7 3.1 17.5 63.4 0.0 M M
15500 -15.4 4.3 225 19 10 2.0 1.1 16.5 61.8 -0.8 972 4.9
15000 -14.9 5.2 210 18 9 7.5 4.1 15.5 59.9 -1.7 941 4.8
14500 -13.6 7.5 215 17 9 9.0 4.9 15.4 59.7 -1.9 886 4.5
14000 -12.2 10.0 215 15 8 9.1 5.0 15.3 59.5 -2.0 830 4.2
13500 -10.8 12.6 220 17 9 9.1 5.0 15.2 59.4 -2.1 775 3.9
13000 -9.5 14.9 225 16 8 9.1 5.0 15.1 59.2 -2.2 719 3.7
12500 -8.1 17.4 240 16 8 8.8 4.8 15.0 59.0 -2.3 663 3.4
12000 -6.9 19.6 250 18 9 8.1 4.5 14.7 58.5 -2.6 613 3.1
11500 -5.6 21.9 260 17 9 8.9 4.9 14.6 58.2 -2.8 559 2.8
11000 -4.3 24.3 265 18 9 8.9 4.9 14.4 58.0 -2.9 505 2.6
10500 -3.0 26.6 255 18 9 8.9 4.9 14.3 57.7 -3.1 450 2.3
10250 -2.3 27.9 250 16 8 8.9 4.9 14.2 57.6 -3.1 423 2.1
10000 -1.6 29.1 250 16 8 8.9 4.9 14.1 57.5 -3.2 395 2.0
9750 -1.0 30.2 255 18 9 8.8 4.9 14.1 57.3 -3.3 368 1.9
9500 -0.3 31.5 255 20 11 8.8 4.8 14.0 57.2 -3.3 341 1.7
9250 0.3 32.5 260 19 10 8.8 4.8 14.0 57.1 -3.4 313 1.6
9000 1.0 33.8 250 18 9 8.8 4.8 13.9 57.0 -3.5 286 1.5
8750 1.7 35.1 250 17 9 8.8 4.8 13.8 56.9 -3.6 259 1.3
8500 2.3 36.1 245 16 8 8.8 4.8 13.7 56.7 -3.6 231 1.2
8250 3.0 37.4 245 14 7 8.8 4.8 13.7 56.6 -3.7 204 1.0
8000 3.7 38.7 240 13 7 8.8 4.8 13.6 56.5 -3.8 177 0.9
7750 4.3 39.7 250 10 5 8.8 4.8 13.5 56.4 -3.9 149 0.8
7500 5.0 41.0 275 5 3 8.8 4.8 13.5 56.2 -4.0 122 0.6
7250 5.7 42.3 275 4 2 8.8 4.8 13.4 56.1 -4.0 95 0.5
7000 6.3 43.3 260 4 2 8.8 4.8 13.3 55.9 -4.1 68 0.3
6750 7.0 44.6 230 4 2 8.9 4.9 13.2 55.8 -4.2 40 0.2
6500 7.6 45.7 180 7 4 8.7 4.8 13.1 55.6 -4.3 13 0.1
6250 8.3 46.9 165 12 6 9.3 5.1 13.1 55.5 -4.4 M M
6000 8.9 48.0 160 17 9 4.7 2.6 12.9 55.3 -4.5 M M
5750 8.7 47.7 160 16 8 -11.8 -6.5 12.0 53.5 -5.5 M M
5500 7.7 45.9 150 15 8 -6.8 -3.7 10.2 50.3 -7.3 M M
5250 7.7 45.9 135 12 6 -1.0 -0.5 9.5 49.1 -8.0 M M
5000 6.6 43.9 125 8 4 -29.9 -16.4 7.7 45.8 -9.9 1 0.0
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
03/12/2025 at 0900 MDT | 03/12/2025 at 1200 MDT
|
CAPE... 0.0 LI... +2.8 | CAPE... +0.8 LI... +2.7
CINH... -0.0 K Index... +15.5 | CINH... -0.1 K Index... +13.1
|
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 -55.6 -68.1 290 31 16 0.5 0.3 | -57.5 -71.5 290 33 17 1.2 0.7
45000 -54.8 -66.6 290 33 17 0.5 0.3 | -55.6 -68.1 295 41 21 1.3 0.7
40000 -52.6 -62.7 300 31 16 1.6 0.9 | -54.0 -65.2 305 42 22 1.0 0.6
38000 -52.0 -61.6 305 30 15 -1.1 -0.6 | -53.3 -63.9 315 44 22 1.2 0.7
36000 -52.7 -62.9 305 24 12 -1.1 -0.6 | -52.6 -62.7 320 46 24 1.2 0.7
34000 -53.4 -64.1 310 18 9 0.0 0.0 | -51.8 -61.2 325 50 25 3.1 1.7
32000 -51.7 -61.1 310 12 6 3.1 1.7 | -49.2 -56.6 325 40 21 4.3 2.4
30000 -49.8 -57.6 300 6 3 5.2 2.9 | -46.6 -51.9 330 30 16 5.6 3.0
29000 -47.6 -53.7 290 6 3 7.6 4.2 | -44.8 -48.6 325 26 14 6.2 3.4
28000 -45.3 -49.5 280 6 3 7.6 4.2 | -42.9 -45.2 325 23 12 6.2 3.4
27000 -43.0 -45.4 270 7 3 7.6 4.2 | -41.1 -42.0 320 19 10 6.1 3.4
26000 -40.6 -41.1 265 8 4 8.6 4.7 | -38.9 -38.0 310 17 9 7.6 4.2
25000 -38.0 -36.4 265 9 5 8.6 4.7 | -36.6 -33.9 300 16 8 7.7 4.2
24000 -35.4 -31.7 265 10 5 8.6 4.7 | -33.8 -28.8 290 15 8 7.6 4.2
23000 -32.9 -27.2 265 11 6 8.4 4.6 | -31.4 -24.5 280 15 8 8.2 4.5
22000 -29.7 -21.5 270 12 6 8.4 4.6 | -28.9 -20.0 275 16 8 8.2 4.5
21000 -27.2 -17.0 270 12 6 8.2 4.5 | -26.5 -15.7 270 17 9 8.0 4.4
20000 -24.9 -12.8 270 12 6 8.0 4.4 | -24.2 -11.6 265 16 8 7.8 4.3
19500 -23.7 -10.7 270 11 6 8.0 4.4 | -23.0 -9.4 260 16 8 7.8 4.3
19000 -22.5 -8.5 270 11 6 8.0 4.4 | -21.9 -7.4 255 15 8 7.8 4.3
18500 -21.3 -6.3 265 11 5 7.7 4.2 | -20.7 -5.3 255 15 8 7.7 4.2
18000 -20.2 -4.4 265 10 5 6.9 3.8 | -19.6 -3.3 250 15 8 7.4 4.1
17500 -19.2 -2.6 260 10 5 7.0 3.8 | -18.5 -1.3 250 15 7 7.5 4.1
17000 -18.2 -0.8 260 10 5 6.3 3.4 | -17.4 0.7 250 14 7 6.8 3.7
16500 -17.3 0.9 255 10 5 6.3 3.5 | -16.4 2.5 245 14 7 6.8 3.7
16000 -16.4 2.5 250 10 5 6.2 3.4 | -15.4 4.3 245 14 7 6.4 3.5
15500 -15.5 4.1 250 10 5 6.1 3.4 | -14.5 5.9 240 14 7 6.2 3.4
15000 -14.6 5.7 245 10 5 6.3 3.4 | -13.6 7.5 240 13 7 6.1 3.4
14500 -13.7 7.3 240 10 5 6.7 3.7 | -12.8 9.0 235 13 7 5.8 3.2
14000 -12.7 9.1 240 9 5 6.8 3.7 | -12.0 10.4 230 12 6 5.8 3.2
13500 -11.6 11.1 235 9 5 8.1 4.4 | -11.1 12.0 230 11 6 6.2 3.4
13000 -10.4 13.3 240 9 5 7.9 4.4 | -10.2 13.6 225 10 5 6.1 3.4
12500 -9.2 15.4 240 9 5 8.5 4.7 | -9.2 15.4 220 10 5 7.7 4.2
12000 -8.0 17.6 240 9 5 8.5 4.7 | -8.1 17.4 220 9 5 7.5 4.1
11500 -6.7 19.9 245 10 5 8.5 4.6 | -6.9 19.6 220 9 4 8.4 4.6
11000 -5.4 22.3 245 10 5 8.6 4.7 | -5.7 21.7 220 8 4 8.3 4.6
10500 -4.3 24.3 250 10 5 6.5 3.6 | -4.6 23.7 220 8 4 6.6 3.6
10250 -3.8 25.2 250 11 5 6.4 3.5 | -4.1 24.6 225 8 4 6.7 3.7
10000 -3.2 26.2 250 11 6 10.3 5.7 | -3.5 25.7 225 8 4 10.7 5.9
9750 -2.4 27.7 245 11 6 10.2 5.6 | -2.6 27.3 220 8 4 10.4 5.7
9500 -1.8 28.8 245 11 6 6.9 3.8 | -2.0 28.4 220 8 4 7.3 4.0
9250 -1.2 29.8 245 11 6 7.6 4.1 | -1.4 29.5 220 8 4 7.5 4.1
9000 -0.7 30.7 250 11 6 8.2 4.5 | -0.8 30.6 220 7 4 9.7 5.3
8750 -0.0 32.0 245 10 5 8.2 4.5 | 0.0 32.0 220 7 4 10.2 5.6
8500 0.6 33.1 240 10 5 7.2 3.9 | 1.3 34.3 220 7 4 9.1 5.0
8250 1.1 34.0 240 9 5 7.8 4.3 | 1.9 35.4 220 7 3 6.5 3.6
8000 2.1 35.8 240 8 4 6.3 3.5 | 2.3 36.1 225 6 3 7.4 4.0
7750 2.7 36.9 230 8 4 7.6 4.2 | 3.1 37.6 225 5 3 10.5 5.7
7500 3.2 37.8 225 7 4 7.1 3.9 | 3.8 38.8 220 5 3 9.2 5.0
7250 3.7 38.7 215 7 3 6.1 3.3 | 4.4 39.9 225 5 3 7.1 3.9
7000 4.1 39.4 215 6 3 6.0 3.3 | 5.0 41.0 230 4 2 9.2 5.0
6750 4.6 40.3 205 6 3 7.4 4.0 | 5.8 42.4 230 5 2 12.3 6.8
6500 5.1 41.2 195 6 3 4.8 2.6 | 6.7 44.1 225 5 2 10.6 5.8
6250 5.3 41.5 185 5 3 1.8 1.0 | 7.5 45.5 230 4 2 10.7 5.8
6000 5.5 41.9 170 4 2 3.7 2.0 | 8.2 46.8 240 4 2 8.6 4.7
5750 5.7 42.3 165 3 2 1.5 0.8 | 8.9 48.0 230 4 2 11.6 6.4
5500 5.2 41.4 115 2 1 -23.1 -12.7 | 11.2 52.2 245 3 2 64.4 35.3
5250 M M M M M M M | M M M M M M M
5000 M M M M M M M | M M M M M M M
03/12/2025 at 1500 MDT | 03/12/2025 at 1800 MDT
|
CAPE... +8.8 LI... +2.5 | CAPE... +5.0 LI... +3.8
CINH... -1.2 K Index... +12.5 | CINH... -2.7 K Index... +8.2
|
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 -59.6 -75.3 275 37 19 1.8 1.0 | -60.6 -77.1 265 37 19 1.5 0.8
45000 -56.9 -70.4 280 46 24 1.7 1.0 | -58.4 -73.1 265 46 24 1.3 0.7
40000 -56.2 -69.2 290 56 29 0.4 0.2 | -57.5 -71.5 270 53 28 0.6 0.3
38000 -55.3 -67.5 295 58 30 2.4 1.3 | -56.3 -69.3 275 56 29 3.1 1.7
36000 -53.9 -65.0 295 57 29 2.4 1.3 | -54.4 -65.9 275 59 31 3.1 1.7
34000 -52.1 -61.8 300 56 29 7.8 4.3 | -52.2 -62.0 280 61 31 7.5 4.1
32000 -47.6 -53.7 300 51 26 7.4 4.0 | -47.9 -54.2 275 54 28 7.1 3.9
30000 -43.3 -45.9 305 46 24 6.9 3.8 | -43.6 -46.5 275 47 24 7.8 4.3
29000 -41.2 -42.2 305 43 22 6.8 3.7 | -41.3 -42.3 275 45 23 7.8 4.3
28000 -39.2 -38.6 305 40 20 6.8 3.7 | -38.9 -38.0 275 43 22 7.8 4.3
27000 -37.1 -34.8 305 37 19 6.8 3.7 | -36.6 -33.9 275 41 21 7.8 4.3
26000 -35.1 -31.2 305 33 17 6.7 3.7 | -34.3 -29.7 275 42 22 7.7 4.2
25000 -32.6 -26.7 305 29 15 6.8 3.7 | -31.4 -24.5 275 43 22 7.7 4.2
24000 -30.5 -22.9 305 26 14 6.8 3.7 | -29.1 -20.4 275 45 23 7.8 4.3
23000 -28.4 -19.1 300 24 12 7.1 3.9 | -26.7 -16.1 275 42 22 8.0 4.4
22000 -26.3 -15.3 295 22 11 7.1 3.9 | -24.3 -11.7 275 40 20 8.0 4.4
21000 -24.2 -11.6 290 21 11 7.0 3.8 | -22.0 -7.6 275 37 19 7.4 4.0
20000 -22.1 -7.8 280 20 10 6.9 3.8 | -19.8 -3.6 275 34 17 7.2 3.9
19500 -21.1 -6.0 280 20 11 6.9 3.8 | -18.7 -1.7 275 32 16 7.2 3.9
19000 -20.0 -4.0 275 21 11 6.9 3.8 | -17.6 0.3 270 30 16 7.2 3.9
18500 -19.0 -2.2 270 21 11 6.7 3.7 | -16.5 2.3 270 29 15 6.6 3.6
18000 -18.0 -0.4 265 20 11 6.3 3.4 | -15.6 3.9 270 27 14 6.1 3.3
17500 -17.1 1.2 260 20 10 6.3 3.5 | -14.7 5.5 265 26 13 6.1 3.4
17000 -16.2 2.8 255 20 10 6.0 3.3 | -13.9 7.0 260 24 13 5.1 2.8
16500 -15.3 4.5 250 19 10 6.1 3.3 | -13.1 8.4 255 23 12 5.2 2.9
16000 -14.5 5.9 245 19 10 5.9 3.2 | -12.4 9.7 250 22 12 4.3 2.4
15500 -13.6 7.5 240 19 10 5.8 3.2 | -11.8 10.8 245 21 11 4.0 2.2
15000 -12.8 9.0 235 19 10 5.9 3.2 | -11.3 11.7 240 21 11 4.0 2.2
14500 -12.0 10.4 230 18 9 5.9 3.2 | -10.7 12.7 235 19 10 4.0 2.2
14000 -11.1 12.0 225 17 9 6.1 3.3 | -10.2 13.6 230 19 10 4.5 2.5
13500 -10.2 13.6 225 17 9 7.1 3.9 | -9.4 15.1 220 18 9 6.6 3.6
13000 -9.1 15.6 220 16 8 7.1 3.9 | -8.5 16.7 215 17 9 6.6 3.6
12500 -8.1 17.4 215 15 8 7.7 4.2 | -7.4 18.7 215 17 9 8.6 4.7
12000 -6.9 19.6 210 14 7 7.6 4.2 | -6.1 21.0 210 16 8 8.5 4.7
11500 -5.7 21.7 210 13 7 8.8 4.8 | -4.9 23.2 210 16 8 8.5 4.6
11000 -4.4 24.1 210 13 7 8.7 4.8 | -3.6 25.5 210 16 8 8.5 4.6
10500 -3.2 26.2 210 12 6 7.3 4.0 | -2.4 27.7 210 16 8 8.2 4.5
10250 -2.7 27.1 210 11 6 8.1 4.5 | -1.8 28.8 210 15 8 8.7 4.8
10000 -1.9 28.6 210 11 6 11.3 6.2 | -1.0 30.2 210 15 8 10.5 5.7
9750 -1.1 30.0 210 11 6 10.6 5.8 | -0.3 31.5 210 16 8 9.9 5.4
9500 -0.4 31.3 210 10 5 8.5 4.7 | 0.4 32.7 210 16 8 8.8 4.8
9250 0.9 33.6 210 9 4 10.1 5.6 | 1.1 34.0 210 15 8 8.9 4.9
9000 1.8 35.2 215 10 5 10.7 5.9 | 1.8 35.2 210 15 8 9.7 5.3
8750 2.5 36.5 215 10 5 9.3 5.1 | 3.2 37.8 210 15 8 9.3 5.1
8500 3.2 37.8 215 10 5 9.7 5.3 | 3.9 39.0 210 15 8 9.2 5.1
8250 3.9 39.0 215 10 5 9.5 5.2 | 4.6 40.3 210 15 8 10.0 5.5
8000 4.6 40.3 215 8 4 9.8 5.4 | 5.4 41.7 210 14 7 10.0 5.5
7750 5.4 41.7 215 8 4 10.4 5.7 | 6.1 43.0 210 14 7 9.2 5.0
7500 6.2 43.2 215 9 5 9.8 5.4 | 6.8 44.2 210 14 7 9.4 5.1
7250 6.8 44.2 215 8 4 8.1 4.4 | 7.5 45.5 210 14 7 9.0 4.9
7000 7.5 45.5 215 7 4 9.5 5.2 | 8.2 46.8 210 13 7 9.4 5.2
6750 8.3 46.9 215 8 4 11.6 6.4 | 8.9 48.0 210 13 7 9.5 5.2
6500 9.1 48.4 215 9 4 10.6 5.8 | 9.6 49.3 210 12 6 10.3 5.6
6250 9.9 49.8 215 7 4 11.1 6.1 | 10.5 50.9 210 12 6 12.3 6.7
6000 10.7 51.3 215 6 3 8.7 4.8 | 11.3 52.3 210 12 6 8.8 4.8
5750 11.4 52.5 220 7 4 12.1 6.7 | 11.8 53.2 210 11 6 6.3 3.4
5500 13.8 56.8 220 5 3 68.5 37.6 | 13.2 55.8 210 9 5 43.3 23.7
5250 M M M M M M M | M M M M M M M
5000 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) and again by approximately 1830 MST/1930 MDT (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 Walker Field in Grand
Junction, Colorado at
North Latitude: 39 deg 07 min 00.001 sec
West Longitude: 108 deg 31 min 59.998 sec
Elevation: 4839 feet (1475 meters)
and may not be representative of other areas along the Western Slope of
Colorado. 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.
CINH (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