- Current Hazards
- Current Conditions
RSS Feeds
Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 261416
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
0816 MDT Thursday, April 26, 2018
This forecast is for Thursday, April 26, 2018:
If the trigger temperature of 62.3 F/16.8 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 795 ft/min (4.0 m/s)
Maximum height of thermals.................. 14798 ft MSL (9959 ft AGL)
Forecast maximum temperature................... 74.0 F/23.8 C
Time of trigger temperature.................... 1030 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................. 13043 ft MSL (8204 ft AGL)
Thermal soaring outlook for Friday 04/27....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:22:10 / 20:01:26 MDT
Total possible sunshine........... 13 hr 39 min 16 sec (819 min 16 sec)
Altitude of sun at 13:11:58 MDT... 64.57 degrees
Upper air data from rawinsonde observation taken on 04/26/2018 at 0600 MDT
Freezing level.................. 10603 ft MSL (5764 ft AGL)
Convective condensation level... 18735 ft MSL (13896 ft AGL)
Lifted condensation level....... 17360 ft MSL (12521 ft AGL)
Lifted index.................... +3.1
K index......................... -2.1
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 -61.5 -78.7 290 37 19 -4.3 -2.3 98.7 209.7 42.9 M M
45000 -62.4 -80.3 305 51 26 -0.6 -0.3 71.4 160.5 29.4 M M
40000 -61.3 -78.3 315 50 26 7.3 4.0 50.0 121.9 17.5 M M
38000 -56.4 -69.5 315 53 27 9.5 5.2 48.5 119.3 17.0 M M
36000 -53.0 -63.4 310 52 27 6.4 3.5 44.9 112.8 14.9 M M
34000 -49.3 -56.7 320 51 26 -3.8 -2.1 41.9 107.4 13.2 M M
32000 -45.5 -49.9 310 48 25 8.0 4.4 38.0 100.4 10.7 M M
30000 -40.8 -41.4 315 39 20 7.7 4.2 36.6 97.9 9.9 M M
29000 -38.5 -37.3 315 35 18 7.7 4.2 35.8 96.4 9.5 M M
28000 -36.1 -33.0 325 38 20 8.9 4.9 35.0 95.0 9.0 M M
27000 -33.3 -27.9 330 42 22 9.4 5.2 34.8 94.7 9.0 M M
26000 -30.4 -22.7 335 46 24 9.3 5.1 34.8 94.6 9.0 M M
25000 -28.2 -18.8 330 49 25 5.5 3.0 34.0 93.2 8.5 M M
24000 -26.6 -15.9 325 50 26 4.1 2.3 32.3 90.1 7.2 M M
23000 -24.2 -11.6 320 48 25 9.8 5.4 31.6 88.8 6.7 M M
22000 -21.5 -6.7 320 47 24 5.4 3.0 31.3 88.4 6.6 M M
21000 -20.0 -4.0 315 45 23 7.4 4.0 29.7 85.4 5.3 M M
20000 -17.6 0.3 310 44 23 7.7 4.2 28.9 84.1 4.7 M M
19500 -16.5 2.3 310 43 22 7.5 4.1 28.6 83.4 4.4 M M
19000 -15.4 4.3 310 42 22 7.0 3.8 28.1 82.6 4.0 M M
18500 -14.3 6.3 315 42 21 7.4 4.1 27.6 81.7 3.7 M M
18000 -13.2 8.2 320 41 21 7.4 4.0 27.2 80.9 3.3 M M
17500 -11.6 11.1 325 41 21 7.4 4.0 26.5 79.8 2.8 M M
17000 -10.5 13.1 330 41 21 7.4 4.1 26.1 79.1 2.4 M M
16500 -9.4 15.1 330 41 21 8.2 4.5 25.8 78.4 2.1 M M
16000 -8.7 16.3 335 40 21 1.5 0.8 24.9 76.9 1.4 M M
15500 -7.9 17.8 330 35 18 7.5 4.1 24.2 75.6 0.7 M M
15000 -7.0 19.4 325 30 16 5.3 2.9 23.7 74.6 0.2 M M
14500 -6.3 20.7 320 26 13 6.2 3.4 22.8 73.1 -0.6 769 3.9
14000 -6.2 20.8 315 22 11 0.2 0.1 21.4 70.5 -2.0 752 3.8
13500 -5.2 22.6 320 19 10 7.0 3.8 20.9 69.6 -2.4 706 3.6
13000 -4.4 24.1 325 17 9 4.3 2.4 20.2 68.3 -3.2 669 3.4
12500 -3.8 25.2 330 15 8 4.6 2.5 19.3 66.8 -4.0 635 3.2
12000 -3.2 26.2 335 13 7 5.1 2.8 18.5 65.4 -4.8 601 3.1
11500 -2.4 27.7 350 13 7 6.7 3.7 17.8 64.0 -5.5 563 2.9
11000 -1.1 30.0 360 14 7 9.2 5.0 17.6 63.8 -5.7 509 2.6
10500 0.3 32.5 355 16 8 9.0 4.9 17.6 63.6 -5.8 453 2.3
10250 1.0 33.8 355 17 9 9.9 5.4 17.5 63.5 -5.9 425 2.2
10000 1.8 35.2 355 16 8 10.8 5.9 17.6 63.7 -5.8 394 2.0
9750 2.6 36.7 360 17 9 10.6 5.8 17.7 63.8 -5.8 363 1.8
9500 3.4 38.1 010 18 9 10.7 5.9 17.7 63.9 -5.8 332 1.7
9250 4.1 39.4 015 19 10 8.0 4.4 17.7 63.9 -5.8 302 1.5
9000 4.6 40.3 020 21 11 5.9 3.2 17.5 63.4 -6.0 281 1.4
8750 5.0 41.0 020 20 10 6.5 3.5 17.2 62.9 -6.3 260 1.3
8500 5.5 41.9 020 18 9 6.1 3.4 16.9 62.5 -6.6 238 1.2
8250 6.0 42.8 025 17 9 6.8 3.8 16.7 62.0 -6.9 217 1.1
8000 6.5 43.7 025 15 8 8.8 4.8 16.5 61.7 -7.0 192 1.0
7750 7.2 45.0 025 15 8 9.6 5.2 16.5 61.7 -7.1 164 0.8
7500 7.9 46.2 025 15 8 9.4 5.1 16.5 61.6 -7.1 135 0.7
7250 8.6 47.5 020 15 8 9.4 5.2 16.4 61.6 -7.2 107 0.5
7000 9.3 48.7 020 15 8 9.4 5.2 16.4 61.6 -7.2 78 0.4
6750 10.0 50.0 020 15 8 9.4 5.2 16.4 61.5 -7.2 50 0.3
6500 10.7 51.3 015 16 8 9.4 5.2 16.4 61.5 -7.3 21 0.1
6250 11.4 52.5 015 16 8 9.4 5.1 16.3 61.4 -7.3 M M
6000 12.1 53.8 010 17 9 9.5 5.2 16.3 61.4 -7.4 M M
5750 12.8 55.0 010 15 8 9.1 5.0 16.3 61.3 -7.4 M M
5500 13.5 56.3 010 12 6 10.5 5.8 16.3 61.3 -7.5 M M
5250 14.1 57.4 005 8 4 -0.5 -0.3 16.1 61.0 -7.7 M M
5000 12.8 55.0 005 5 3 -39.2 -21.5 14.0 57.2 -9.8 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/26/2018 at 0900 MDT | 04/26/2018 at 1200 MDT
|
K index... -14.9 LI... +7.1 | K index... -17.8 LI... +6.8
CAPE... 0.0 CIN... 0.0 | CAPE... 0.0 CIN... 0.0
|
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 -62.6 -80.7 315 31 16 -0.2 -0.1 | -62.4 -80.3 315 29 15 -0.9 -0.5
45000 -62.7 -80.9 315 38 20 1.7 0.9 | -63.5 -82.3 315 34 18 1.7 0.9
40000 -60.3 -76.5 330 32 17 1.8 1.0 | -61.1 -78.0 325 25 13 1.8 1.0
38000 -57.1 -70.8 335 33 17 6.6 3.6 | -57.9 -72.2 330 26 13 6.7 3.7
36000 -53.1 -63.6 340 35 18 6.6 3.6 | -53.9 -65.0 340 29 15 6.7 3.7
34000 -48.6 -55.5 345 38 19 6.8 3.7 | -49.1 -56.4 350 30 16 7.4 4.0
32000 -44.6 -48.3 355 40 20 6.8 3.7 | -44.7 -48.5 360 29 15 7.4 4.0
30000 -40.3 -40.5 360 42 22 7.6 4.2 | -40.1 -40.2 005 29 15 8.1 4.4
29000 -38.0 -36.4 360 43 22 7.6 4.2 | -37.7 -35.9 005 30 15 8.1 4.4
28000 -35.7 -32.3 005 44 23 7.6 4.2 | -35.2 -31.4 005 30 16 8.1 4.4
27000 -33.4 -28.1 005 45 23 8.2 4.5 | -32.8 -27.0 360 31 16 8.2 4.5
26000 -30.9 -23.6 005 45 23 8.2 4.5 | -30.3 -22.5 360 33 17 8.2 4.5
25000 -28.5 -19.3 005 44 23 8.2 4.5 | -27.9 -18.2 360 34 18 8.2 4.5
24000 -26.0 -14.8 005 44 22 8.2 4.5 | -25.4 -13.7 355 35 18 8.1 4.4
23000 -23.6 -10.5 005 43 22 8.2 4.5 | -23.0 -9.4 360 35 18 8.1 4.4
22000 -21.1 -6.0 005 42 22 8.2 4.5 | -20.6 -5.1 360 34 18 8.1 4.4
21000 -18.7 -1.7 005 41 21 7.3 4.0 | -18.3 -0.9 360 33 17 7.4 4.0
20000 -16.5 2.3 005 40 20 7.3 4.0 | -16.0 3.2 005 32 17 7.4 4.0
19500 -15.4 4.3 005 39 20 7.3 4.0 | -14.4 6.1 005 31 16 7.4 4.0
19000 -13.8 7.2 005 38 19 7.1 3.9 | -13.3 8.1 005 31 16 7.0 3.8
18500 -12.7 9.1 005 37 19 6.9 3.8 | -12.3 9.9 010 30 15 6.7 3.7
18000 -11.7 10.9 005 35 18 7.1 3.9 | -11.3 11.7 015 29 15 6.7 3.7
17500 -10.8 12.6 010 34 18 5.5 3.0 | -10.3 13.5 015 28 14 6.1 3.3
17000 -9.9 14.2 010 33 17 5.6 3.1 | -9.4 15.1 020 26 14 6.1 3.4
16500 -9.1 15.6 010 32 16 5.9 3.3 | -8.5 16.7 020 25 13 6.1 3.3
16000 -8.2 17.2 010 30 15 6.1 3.3 | -7.6 18.3 020 24 12 6.1 3.3
15500 -7.3 18.9 005 28 15 5.7 3.1 | -6.7 19.9 025 22 12 6.0 3.3
15000 -6.6 20.1 360 27 14 4.3 2.4 | -5.8 21.6 025 22 11 5.7 3.1
14500 -5.9 21.4 355 26 13 4.4 2.4 | -4.9 23.2 020 21 11 5.7 3.1
14000 -5.4 22.3 355 25 13 3.5 1.9 | -4.2 24.4 020 20 10 4.8 2.6
13500 -4.9 23.2 350 25 13 3.5 1.9 | -3.4 25.9 020 20 10 4.8 2.7
13000 -4.2 24.4 350 24 12 5.8 3.2 | -2.7 27.1 020 20 10 5.4 2.9
12500 -3.4 25.9 350 23 12 5.7 3.1 | -1.9 28.6 020 20 10 5.5 3.0
12000 -2.6 27.3 355 22 11 6.3 3.4 | -1.2 29.8 020 20 11 3.7 2.0
11500 -1.7 28.9 360 22 11 6.3 3.5 | -0.7 30.7 025 20 10 4.0 2.2
11000 -0.8 30.6 010 22 11 6.0 3.3 | -0.2 31.6 025 19 10 4.1 2.3
10500 0.1 32.2 015 22 11 6.8 3.7 | 0.3 32.5 030 15 8 4.9 2.7
10250 0.5 32.9 020 22 11 3.2 1.7 | 0.6 33.1 030 14 7 2.5 1.4
10000 0.7 33.3 025 22 11 5.0 2.7 | 0.8 33.4 030 14 7 5.8 3.2
9750 1.3 34.3 025 21 11 9.9 5.4 | 1.4 34.5 030 13 7 10.8 5.9
9500 1.9 35.4 030 19 10 8.8 4.8 | 2.1 35.8 030 13 6 9.6 5.2
9250 2.5 36.5 035 19 10 8.0 4.4 | 2.8 37.0 030 12 6 8.7 4.8
9000 3.1 37.6 035 17 9 8.1 4.4 | 3.4 38.1 030 12 6 8.8 4.8
8750 3.8 38.8 040 16 8 10.2 5.6 | 4.2 39.6 030 12 6 10.5 5.8
8500 4.6 40.3 045 15 8 10.1 5.5 | 5.0 41.0 030 12 6 10.4 5.7
8250 5.3 41.5 045 14 7 8.8 4.8 | 5.7 42.3 030 11 6 10.0 5.5
8000 6.0 42.8 050 13 7 8.1 4.4 | 6.5 43.7 030 11 6 9.9 5.5
7750 6.6 43.9 050 13 6 8.4 4.6 | 7.2 45.0 030 11 6 10.8 5.9
7500 7.2 45.0 050 12 6 6.0 3.3 | 8.1 46.6 030 11 6 10.5 5.7
7250 7.5 45.5 050 11 6 3.6 2.0 | 8.8 47.8 030 11 5 9.7 5.3
7000 7.8 46.0 050 10 5 3.8 2.1 | 9.5 49.1 030 10 5 9.8 5.4
6750 8.1 46.6 050 10 5 3.8 2.1 | 10.3 50.5 030 10 5 10.5 5.8
6500 8.4 47.1 045 8 4 4.2 2.3 | 11.1 52.0 030 10 5 11.0 6.0
6250 8.7 47.7 045 8 4 4.9 2.7 | 11.9 53.4 030 10 5 11.7 6.4
6000 9.0 48.2 045 7 3 3.2 1.8 | 12.8 55.0 030 9 5 8.9 4.9
5750 9.4 48.9 045 6 3 9.1 5.0 | 13.5 56.3 030 9 4 16.4 9.0
5500 10.6 51.1 045 5 3 23.9 13.1 | 15.5 59.9 030 9 5 37.0 20.3
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
04/26/2018 at 1500 MDT | 04/26/2018 at 1800 MDT
|
K index... -15.3 LI... +5.1 | K index... -14.8 LI... +4.9
CAPE... 0.0 CIN... 0.0 | CAPE... 0.0 CIN... 0.0
|
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 -62.3 -80.1 315 28 14 -0.6 -0.3 | -62.5 -80.5 310 28 14 -0.8 -0.4
45000 -63.1 -81.6 315 30 16 1.1 0.6 | -63.4 -82.1 310 29 15 1.5 0.8
40000 -61.4 -78.5 325 19 10 1.1 0.6 | -61.2 -78.2 315 14 7 1.4 0.8
38000 -58.3 -72.9 335 20 11 6.3 3.5 | -58.0 -72.4 335 13 7 6.4 3.5
36000 -54.5 -66.1 340 23 12 6.3 3.5 | -54.2 -65.6 350 14 7 6.4 3.5
34000 -50.3 -58.5 340 24 12 8.1 4.4 | -50.0 -58.0 355 16 8 7.6 4.2
32000 -44.8 -48.6 340 22 12 8.1 4.4 | -44.8 -48.6 345 18 9 7.6 4.2
30000 -39.9 -39.8 340 22 11 8.5 4.6 | -39.9 -39.8 340 19 10 8.5 4.7
29000 -37.3 -35.1 340 23 12 8.5 4.6 | -37.4 -35.3 340 19 10 8.5 4.7
28000 -34.8 -30.6 340 23 12 8.5 4.6 | -34.8 -30.6 340 20 10 8.5 4.7
27000 -32.3 -26.1 345 24 12 8.2 4.5 | -32.3 -26.1 340 19 10 8.4 4.6
26000 -29.9 -21.8 345 24 12 8.2 4.5 | -29.8 -21.6 345 19 10 8.4 4.6
25000 -27.4 -17.3 350 25 13 8.1 4.5 | -27.2 -17.0 345 19 10 8.4 4.6
24000 -25.0 -13.0 355 26 13 7.8 4.3 | -24.8 -12.6 350 18 9 7.8 4.3
23000 -22.7 -8.9 355 25 13 7.8 4.3 | -22.5 -8.5 355 17 9 7.8 4.3
22000 -20.4 -4.7 360 25 13 7.8 4.3 | -20.1 -4.2 360 16 8 7.8 4.3
21000 -18.1 -0.6 005 25 13 7.3 4.0 | -17.9 -0.2 005 15 8 7.3 4.0
20000 -15.9 3.4 005 24 12 7.3 4.0 | -15.7 3.7 005 14 7 7.3 4.0
19500 -14.8 5.4 005 23 12 7.3 4.0 | -14.6 5.7 005 14 7 7.3 4.0
19000 -13.7 7.3 005 22 12 7.4 4.0 | -13.5 7.7 010 13 7 7.3 4.0
18500 -12.6 9.3 010 22 11 7.4 4.1 | -12.4 9.7 010 12 6 7.3 4.0
18000 -11.5 11.3 010 21 11 7.4 4.1 | -11.4 11.5 010 12 6 7.2 4.0
17500 -10.4 13.3 010 20 10 7.1 3.9 | -10.2 13.6 010 11 6 7.9 4.3
17000 -9.3 15.3 015 19 10 7.1 3.9 | -9.0 15.8 010 10 5 7.9 4.3
16500 -8.2 17.2 020 19 10 7.1 3.9 | -7.8 18.0 015 10 5 7.5 4.1
16000 -7.2 19.0 020 18 9 7.1 3.9 | -6.8 19.8 015 9 5 6.9 3.8
15500 -5.6 21.9 025 17 9 6.6 3.6 | -5.3 22.5 020 9 4 7.3 4.0
15000 -4.6 23.7 030 16 8 6.3 3.5 | -4.1 24.6 025 9 4 7.4 4.1
14500 -3.7 25.3 035 15 8 6.5 3.6 | -3.0 26.6 025 8 4 7.3 4.0
14000 -2.7 27.1 035 15 8 6.9 3.8 | -1.9 28.6 030 8 4 7.0 3.8
13500 -1.6 29.1 035 14 7 6.6 3.6 | -0.9 30.4 030 8 4 7.0 3.8
13000 -0.8 30.6 035 14 7 5.0 2.7 | 0.1 32.2 035 8 4 6.7 3.7
12500 -0.0 32.0 035 14 7 4.9 2.7 | 1.1 34.0 040 8 4 6.7 3.7
12000 0.6 33.1 035 14 7 3.6 2.0 | 2.0 35.6 040 9 4 5.7 3.1
11500 1.1 34.0 030 14 7 4.3 2.3 | 2.9 37.2 035 10 5 5.9 3.2
11000 1.8 35.2 030 13 7 6.8 3.8 | 3.7 38.7 035 11 5 5.9 3.2
10500 2.8 37.0 025 13 6 4.8 2.6 | 4.5 40.1 030 11 6 4.6 2.5
10250 3.0 37.4 025 12 6 4.7 2.6 | 4.8 40.6 030 11 6 5.8 3.2
10000 3.6 38.5 025 12 6 9.6 5.3 | 5.4 41.7 035 11 6 9.4 5.2
9750 4.3 39.7 025 12 6 10.7 5.9 | 6.1 43.0 035 11 6 9.6 5.2
9500 5.0 41.0 025 12 6 9.8 5.4 | 6.7 44.1 035 12 6 8.9 4.9
9250 5.7 42.3 025 11 6 8.6 4.7 | 7.3 45.1 035 11 6 7.6 4.2
9000 6.4 43.5 025 11 6 10.1 5.5 | 7.9 46.2 035 11 6 9.0 4.9
8750 7.2 45.0 025 11 6 11.7 6.4 | 8.6 47.5 035 11 6 10.3 5.7
8500 8.0 46.4 025 11 6 10.6 5.8 | 9.4 48.9 035 11 6 10.1 5.5
8250 8.8 47.8 030 11 6 10.0 5.5 | 10.1 50.2 035 11 5 10.4 5.7
8000 9.6 49.3 030 11 6 9.8 5.4 | 10.9 51.6 040 11 5 10.0 5.5
7750 10.3 50.5 030 11 5 9.4 5.2 | 11.6 52.9 040 10 5 9.5 5.2
7500 11.0 51.8 030 10 5 10.0 5.5 | 12.3 54.1 040 10 5 9.9 5.4
7250 11.8 53.2 030 10 5 10.6 5.8 | 13.1 55.6 040 10 5 10.2 5.6
7000 12.5 54.5 030 10 5 9.8 5.4 | 13.9 57.0 040 10 5 10.1 5.5
6750 13.3 55.9 030 10 5 9.9 5.4 | 14.6 58.3 040 10 5 10.2 5.6
6500 14.1 57.4 030 10 5 11.0 6.0 | 15.4 59.7 040 10 5 10.2 5.6
6250 14.9 58.8 030 9 5 11.0 6.1 | 16.2 61.2 040 9 5 10.5 5.8
6000 15.7 60.3 030 9 5 11.3 6.2 | 16.9 62.4 045 9 5 9.5 5.2
5750 16.6 61.9 030 9 4 14.3 7.9 | 17.6 63.7 045 9 4 9.8 5.4
5500 17.8 64.0 030 9 4 16.7 9.2 | 18.4 65.1 040 8 4 11.3 6.2
5250 19.0 66.2 030 9 4 14.9 8.2 | 19.2 66.6 040 8 4 10.1 5.5
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.
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
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