Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 261307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Friday, April 26, 2024
This forecast is for Friday, April 26, 2024:
If the trigger temperature of 58.5 F/14.7 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 536 ft/min (2.7 m/s)
Maximum height of thermals.................. 15577 ft MSL (10738 ft AGL)
Forecast maximum temperature................... 67.0 F/19.9 C
Time of trigger temperature.................... 0930 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................. 11707 ft MSL (6868 ft AGL)
Thermal soaring outlook for Saturday 04/27..... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:20:59 / 20:02:38 MDT
Total possible sunshine........... 13 hr 41 min 38 sec (821 min 38 sec)
Altitude of sun at 13:11:49 MDT... 64.61 degrees
Upper air data from rawinsonde observation taken on 04/26/2024 at 0600 MDT
Freezing level.................. 9941 ft MSL (5102 ft AGL)
Convective condensation level... 12409 ft MSL (7570 ft AGL)
Lifted condensation level....... 13603 ft MSL (8763 ft AGL)
Lifted index.................... -2.0
K index......................... +24.2
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 -49.5 -57.1 225 32 17 6.6 3.6 119.4 246.9 57.0 M M
45000 -51.5 -60.7 245 25 13 2.7 1.5 89.9 193.9 43.0 M M
40000 -50.7 -59.3 260 35 18 0.2 0.1 68.1 154.5 31.7 M M
38000 -52.1 -61.8 285 30 16 -4.7 -2.6 57.1 134.8 25.2 M M
36000 -53.8 -64.8 290 31 16 3.5 1.9 46.0 114.8 18.3 M M
34000 -52.1 -61.8 300 29 15 2.1 1.1 40.1 104.1 14.5 M M
32000 -50.8 -59.4 300 37 19 4.4 2.4 32.7 90.9 9.6 M M
30000 -48.3 -54.9 290 19 10 7.5 4.1 28.2 82.8 6.5 M M
29000 -45.5 -49.9 280 17 9 9.5 5.2 28.0 82.3 6.4 M M
28000 -42.7 -44.9 285 13 7 9.3 5.1 27.8 82.1 6.4 M M
27000 -40.0 -40.0 275 15 8 8.6 4.7 27.6 81.7 6.3 M M
26000 -37.4 -35.3 305 14 7 8.6 4.7 27.2 81.0 6.1 M M
25000 -34.8 -30.6 290 15 8 8.7 4.7 26.8 80.2 5.8 M M
24000 -32.2 -26.0 275 11 6 8.1 4.4 26.3 79.3 5.5 M M
23000 -30.0 -22.0 270 15 8 7.9 4.3 25.5 77.9 4.8 M M
22000 -27.6 -17.7 285 13 7 7.9 4.4 24.8 76.7 4.4 M M
21000 -25.3 -13.5 275 23 12 7.8 4.3 24.1 75.5 3.8 M M
20000 -22.9 -9.2 270 21 11 8.2 4.5 23.5 74.2 3.3 M M
19500 -22.0 -7.6 275 22 11 4.6 2.5 22.9 73.2 2.8 M M
19000 -21.0 -5.8 270 21 11 7.3 4.0 22.3 72.1 2.3 M M
18500 -20.0 -4.0 265 20 10 7.0 3.8 21.8 71.2 1.9 M M
18000 -18.9 -2.0 275 22 11 8.6 4.7 21.5 70.6 1.6 M M
17500 -17.0 1.4 285 23 12 8.5 4.6 21.1 70.0 1.2 M M
17000 -15.8 3.6 285 22 12 8.5 4.7 20.9 69.6 1.0 M M
16500 -14.5 5.9 290 20 10 8.7 4.8 20.7 69.2 0.8 M M
16000 -13.4 7.9 285 16 8 5.9 3.2 20.3 68.5 0.4 M M
15500 -12.6 9.3 285 18 9 7.1 3.9 19.6 67.2 -0.2 923 4.7
15000 -11.2 11.8 280 17 9 10.6 5.8 19.5 67.2 -0.3 866 4.4
14500 -9.8 14.4 270 15 8 7.1 3.9 19.5 67.1 -0.4 811 4.1
14000 -9.0 15.8 265 15 8 5.7 3.1 18.9 66.0 -1.0 769 3.9
13500 -8.1 17.4 260 13 7 5.8 3.2 18.2 64.8 -1.6 730 3.7
13000 -7.3 18.9 265 16 8 6.2 3.4 17.5 63.6 -2.2 690 3.5
12500 -6.2 20.8 265 21 11 8.3 4.6 17.2 63.0 -2.6 642 3.3
12000 -5.0 23.0 265 24 12 8.2 4.5 17.0 62.5 -2.9 591 3.0
11500 -3.8 25.2 260 24 12 8.2 4.5 16.7 62.1 -3.1 540 2.7
11000 -2.6 27.3 265 23 12 8.2 4.5 16.4 61.6 -3.4 489 2.5
10500 -1.4 29.5 260 21 11 8.2 4.5 16.2 61.1 -3.7 438 2.2
10250 -0.8 30.6 260 20 10 8.2 4.5 16.1 60.9 -3.8 413 2.1
10000 -0.2 31.6 265 19 10 8.2 4.5 15.9 60.7 -4.0 387 2.0
9750 0.5 32.9 265 17 9 8.2 4.5 15.8 60.4 -4.1 362 1.8
9500 1.1 34.0 265 15 8 8.3 4.5 15.7 60.2 -4.2 336 1.7
9250 1.7 35.1 270 14 7 8.3 4.5 15.6 60.1 -4.3 310 1.6
9000 2.3 36.1 270 9 5 8.3 4.5 15.5 59.9 -4.4 284 1.4
8750 2.9 37.2 265 8 4 8.3 4.5 15.4 59.6 -4.6 258 1.3
8500 3.5 38.3 255 7 3 8.3 4.5 15.2 59.4 -4.7 233 1.2
8250 4.1 39.4 240 6 3 8.3 4.5 15.1 59.2 -4.8 207 1.1
8000 4.8 40.6 225 5 3 8.3 4.5 15.0 59.0 -4.9 181 0.9
7750 5.4 41.7 225 6 3 8.3 4.5 14.9 58.8 -5.1 155 0.8
7500 6.0 42.8 220 4 2 8.3 4.5 14.8 58.6 -5.2 129 0.7
7250 6.6 43.9 215 3 2 8.3 4.5 14.7 58.4 -5.3 103 0.5
7000 7.2 45.0 195 5 3 8.3 4.5 14.6 58.2 -5.5 78 0.4
6750 7.8 46.0 190 6 3 8.3 4.5 14.4 58.0 -5.6 52 0.3
6500 8.4 47.1 170 7 4 8.3 4.5 14.3 57.8 -5.7 26 0.1
6250 9.1 48.4 160 8 4 8.2 4.5 14.2 57.5 -5.9 0 0.0
6000 9.7 49.5 155 12 6 8.4 4.6 14.1 57.3 -6.0 M M
5750 10.3 50.5 150 12 6 6.3 3.5 13.9 57.0 -6.2 M M
5500 10.6 51.1 145 10 5 4.5 2.5 13.5 56.4 -6.6 M M
5250 10.9 51.6 135 9 4 5.5 3.0 13.2 55.7 -7.0 M M
5000 11.3 52.3 120 6 3 3.5 1.9 12.8 55.1 -7.4 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/26/2024 at 0900 MDT | 04/26/2024 at 1200 MDT
|
CAPE... +5.9 LI... +0.2 | CAPE... +136.7 LI... -0.8
CINH... -7.2 K Index... +23.8 | CINH... -2.1 K Index... +25.6
|
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 -51.3 -60.3 235 29 15 1.1 0.6 | -51.7 -61.1 240 30 15 0.9 0.5
45000 -49.7 -57.5 245 32 16 0.2 0.1 | -50.3 -58.5 250 36 19 0.2 0.1
40000 -52.2 -62.0 265 35 18 -1.7 -0.9 | -51.8 -61.2 245 36 18 -1.0 -0.6
38000 -52.9 -63.2 270 36 18 -0.3 -0.2 | -52.4 -62.3 245 35 18 -1.1 -0.6
36000 -53.1 -63.6 270 35 18 -0.3 -0.2 | -53.1 -63.6 240 32 17 -1.1 -0.6
34000 -53.0 -63.4 270 34 17 5.5 3.0 | -53.5 -64.3 230 30 16 5.0 2.8
32000 -49.2 -56.6 275 31 16 6.3 3.5 | -49.8 -57.6 230 26 13 6.2 3.4
30000 -45.4 -49.7 280 29 15 7.3 4.0 | -46.0 -50.8 230 22 11 8.2 4.5
29000 -43.2 -45.8 275 27 14 7.2 4.0 | -43.5 -46.3 230 20 11 8.2 4.5
28000 -41.1 -42.0 275 24 12 7.2 4.0 | -41.1 -42.0 225 19 10 8.2 4.5
27000 -38.9 -38.0 275 22 11 7.1 3.9 | -38.6 -37.5 225 17 9 8.3 4.5
26000 -36.6 -33.9 275 19 10 8.2 4.5 | -36.3 -33.3 220 16 8 7.4 4.1
25000 -34.1 -29.4 275 17 9 8.2 4.5 | -34.1 -29.4 215 15 8 7.4 4.1
24000 -31.7 -25.1 275 14 7 8.2 4.5 | -31.9 -25.4 210 14 7 7.4 4.1
23000 -29.3 -20.7 275 13 7 7.7 4.2 | -29.6 -21.3 210 13 7 8.1 4.5
22000 -26.5 -15.7 275 12 6 7.7 4.2 | -27.1 -16.8 215 13 7 8.2 4.5
21000 -24.2 -11.6 280 11 6 7.5 4.1 | -24.1 -11.4 215 14 7 7.8 4.3
20000 -22.1 -7.8 275 13 7 7.3 4.0 | -21.9 -7.4 215 14 7 7.3 4.0
19500 -21.0 -5.8 270 14 7 7.3 4.0 | -20.9 -5.6 215 14 7 7.3 4.0
19000 -19.9 -3.8 270 15 8 7.3 4.0 | -19.8 -3.6 215 14 7 7.3 4.0
18500 -18.8 -1.8 270 16 8 7.3 4.0 | -18.7 -1.7 215 15 7 7.2 4.0
18000 -17.8 -0.0 265 16 8 7.2 4.0 | -17.7 0.1 220 15 8 6.9 3.8
17500 -16.7 1.9 265 17 9 7.3 4.0 | -16.7 1.9 220 16 8 6.9 3.8
17000 -15.7 3.7 260 18 9 7.0 3.8 | -15.6 3.9 220 17 8 7.4 4.1
16500 -14.7 5.5 260 18 9 7.0 3.8 | -14.6 5.7 220 17 9 7.4 4.1
16000 -13.6 7.5 255 19 10 7.0 3.8 | -13.5 7.7 220 18 9 7.5 4.1
15500 -12.6 9.3 255 18 9 7.0 3.9 | -12.4 9.7 220 19 10 7.5 4.1
15000 -11.6 11.1 250 18 9 7.1 3.9 | -11.3 11.7 220 20 10 7.5 4.1
14500 -10.6 12.9 250 18 9 7.2 3.9 | -10.2 13.6 220 20 11 7.2 4.0
14000 -9.5 14.9 245 18 9 7.2 3.9 | -9.2 15.4 220 21 11 7.2 4.0
13500 -8.4 16.9 245 18 9 7.6 4.2 | -8.1 17.4 220 21 11 7.8 4.3
13000 -7.3 18.9 240 18 9 7.6 4.1 | -7.0 19.4 220 20 11 7.8 4.3
12500 -6.2 20.8 240 18 9 7.6 4.2 | -5.9 21.4 225 20 10 7.6 4.2
12000 -5.1 22.8 240 18 9 7.5 4.1 | -4.8 23.4 225 19 10 7.6 4.2
11500 -4.0 24.8 240 17 9 8.1 4.4 | -3.6 25.5 225 18 9 7.9 4.3
11000 -2.8 27.0 235 17 9 8.2 4.5 | -2.5 27.5 225 16 8 7.9 4.3
10500 -1.7 28.9 235 16 8 7.0 3.8 | -1.4 29.5 225 15 8 7.2 3.9
10250 -1.1 30.0 240 16 8 7.5 4.1 | -0.8 30.6 225 14 7 8.1 4.4
10000 -0.5 31.1 240 15 8 9.8 5.4 | -0.1 31.8 225 13 7 10.1 5.6
9750 0.2 32.4 235 15 8 9.1 5.0 | 0.6 33.1 225 14 7 9.9 5.4
9500 0.8 33.4 235 14 7 7.3 4.0 | 1.3 34.3 225 13 7 9.1 5.0
9250 1.4 34.5 235 14 7 7.7 4.2 | 2.0 35.6 225 12 6 9.1 5.0
9000 1.9 35.4 235 13 7 7.3 4.0 | 2.7 36.9 230 11 6 9.4 5.1
8750 2.4 36.3 230 12 6 7.2 4.0 | 3.4 38.1 225 12 6 9.9 5.4
8500 3.0 37.4 225 11 6 7.5 4.1 | 4.1 39.4 230 11 6 10.0 5.5
8250 4.1 39.4 220 10 5 8.1 4.5 | 4.9 40.8 230 11 6 10.1 5.5
8000 4.7 40.5 225 10 5 8.3 4.6 | 6.3 43.3 230 11 6 9.5 5.2
7750 5.3 41.5 220 10 5 7.4 4.1 | 7.1 44.8 230 11 5 10.1 5.5
7500 5.9 42.6 210 9 5 8.1 4.4 | 7.8 46.0 230 10 5 10.3 5.6
7250 6.4 43.5 205 9 5 6.3 3.4 | 8.5 47.3 230 10 5 8.9 4.9
7000 6.9 44.4 205 9 5 6.5 3.6 | 9.2 48.6 235 10 5 9.2 5.0
6750 7.4 45.3 200 9 5 8.3 4.6 | 9.9 49.8 235 10 5 10.8 5.9
6500 8.0 46.4 190 9 4 8.1 4.4 | 10.7 51.3 230 9 5 10.6 5.8
6250 8.7 47.7 190 8 4 10.5 5.8 | 11.5 52.7 230 9 5 11.1 6.1
6000 9.5 49.1 190 7 4 8.8 4.8 | 12.5 54.5 235 9 4 16.8 9.2
5750 10.0 50.0 190 7 4 8.7 4.8 | 14.1 57.4 240 8 4 26.1 14.3
5500 11.9 53.4 185 6 3 54.5 29.9 | 15.7 60.3 240 8 4 9.6 5.3
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
04/26/2024 at 1500 MDT | 04/26/2024 at 1800 MDT
|
CAPE... +356.5 LI... -1.5 | CAPE... +156.6 LI... -0.1
CINH... -11.1 K Index... +25.7 | CINH... -29.4 K Index... +24.3
|
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 -52.1 -61.8 235 30 15 1.3 0.7 | -51.7 -61.1 235 27 14 1.3 0.7
45000 -50.1 -58.2 250 32 17 0.7 0.4 | -49.6 -57.3 240 30 15 0.7 0.4
40000 -50.2 -58.4 235 33 17 -0.1 -0.1 | -49.4 -56.9 220 32 16 0.1 0.0
38000 -50.7 -59.3 225 33 17 -2.1 -1.1 | -50.1 -58.2 215 31 16 -3.0 -1.6
36000 -51.9 -61.4 220 31 16 -2.1 -1.1 | -51.8 -61.2 200 26 13 -3.0 -1.6
34000 -53.1 -63.6 215 30 15 3.1 1.7 | -53.6 -64.5 185 23 12 -0.9 -0.5
32000 -50.2 -58.4 205 26 14 4.9 2.7 | -51.0 -59.8 170 19 10 4.7 2.6
30000 -47.1 -52.8 200 24 12 8.7 4.8 | -48.2 -54.8 150 17 9 7.2 3.9
29000 -44.4 -47.9 200 22 11 9.1 5.0 | -45.4 -49.7 160 17 9 9.4 5.2
28000 -41.7 -43.1 200 20 10 9.1 5.0 | -42.5 -44.5 165 17 9 9.4 5.2
27000 -39.0 -38.2 205 18 9 9.1 5.0 | -39.0 -38.2 170 18 9 9.5 5.2
26000 -36.4 -33.5 205 18 9 8.4 4.6 | -36.3 -33.3 175 18 9 8.8 4.8
25000 -33.9 -29.0 205 17 9 8.4 4.6 | -33.7 -28.7 180 19 10 8.8 4.8
24000 -31.4 -24.5 205 17 9 8.4 4.6 | -31.0 -23.8 180 20 10 8.9 4.9
23000 -29.0 -20.2 205 17 9 7.7 4.2 | -28.6 -19.5 185 21 11 8.0 4.4
22000 -26.7 -16.1 200 18 9 7.7 4.2 | -26.2 -15.2 190 22 12 8.0 4.4
21000 -23.9 -11.0 195 19 10 7.5 4.1 | -23.8 -10.8 190 24 12 7.9 4.3
20000 -21.7 -7.1 195 19 10 7.3 4.0 | -21.6 -6.9 195 25 13 7.5 4.1
19500 -20.7 -5.3 195 19 10 7.3 4.0 | -20.5 -4.9 195 26 13 7.5 4.1
19000 -19.6 -3.3 195 19 10 7.3 4.0 | -19.4 -2.9 195 27 14 7.5 4.1
18500 -18.5 -1.3 190 19 10 7.3 4.0 | -18.3 -0.9 195 28 14 7.5 4.1
18000 -17.4 0.7 190 19 10 7.1 3.9 | -17.2 1.0 195 28 15 7.0 3.8
17500 -16.4 2.5 195 19 10 7.1 3.9 | -16.2 2.8 200 29 15 7.0 3.9
17000 -15.3 4.5 195 20 10 7.5 4.1 | -15.1 4.8 200 29 15 7.0 3.9
16500 -14.2 6.4 195 20 10 7.6 4.2 | -14.1 6.6 200 29 15 7.0 3.9
16000 -13.1 8.4 195 20 10 7.7 4.2 | -13.1 8.4 200 29 15 7.1 3.9
15500 -12.0 10.4 195 20 10 7.9 4.3 | -12.0 10.4 200 29 15 7.2 3.9
15000 -10.9 12.4 195 21 11 7.9 4.3 | -11.0 12.2 205 29 15 7.2 3.9
14500 -9.7 14.5 200 20 11 7.7 4.2 | -9.9 14.2 205 28 15 7.0 3.8
14000 -8.6 16.5 200 20 10 7.7 4.2 | -8.9 16.0 205 28 14 7.0 3.8
13500 -7.5 18.5 200 20 10 7.5 4.1 | -7.9 17.8 210 27 14 6.9 3.8
13000 -6.4 20.5 200 19 10 7.5 4.1 | -6.9 19.6 210 27 14 6.9 3.8
12500 -5.3 22.5 200 18 9 7.6 4.1 | -5.9 21.4 210 26 13 6.8 3.7
12000 -4.2 24.4 205 17 9 7.6 4.2 | -4.9 23.2 215 25 13 6.8 3.7
11500 -3.2 26.2 205 17 9 7.5 4.1 | -3.9 25.0 215 24 12 6.9 3.8
11000 -2.1 28.2 205 16 8 7.6 4.1 | -2.9 26.8 215 22 12 6.9 3.8
10500 -1.1 30.0 210 15 8 5.3 2.9 | -1.9 28.6 220 21 11 6.0 3.3
10250 -0.7 30.7 205 14 7 6.2 3.4 | -1.5 29.3 220 21 11 5.7 3.1
10000 -0.1 31.8 210 14 7 9.2 5.1 | -1.0 30.2 220 21 11 7.5 4.1
9750 0.6 33.1 210 14 7 9.3 5.1 | -0.4 31.3 220 19 10 7.7 4.2
9500 1.2 34.2 215 13 7 8.3 4.6 | 0.0 32.0 220 18 9 5.9 3.2
9250 1.8 35.2 210 13 6 8.2 4.5 | 0.4 32.7 220 18 9 5.0 2.7
9000 2.4 36.3 210 12 6 8.3 4.6 | 0.8 33.4 225 18 9 5.9 3.3
8750 3.0 37.4 220 12 6 8.6 4.7 | 1.8 35.2 225 14 7 6.9 3.8
8500 3.7 38.7 220 12 6 8.6 4.7 | 2.3 36.1 225 13 7 7.0 3.8
8250 4.3 39.7 220 11 6 9.0 4.9 | 2.8 37.0 230 13 7 6.8 3.7
8000 5.5 41.9 230 10 5 7.5 4.1 | 3.3 37.9 230 10 5 6.6 3.6
7750 6.1 43.0 235 10 5 8.5 4.7 | 3.7 38.7 235 9 5 6.5 3.6
7500 6.7 44.1 235 9 5 8.9 4.9 | 4.2 39.6 235 8 4 6.9 3.8
7250 7.3 45.1 240 9 5 6.4 3.5 | 4.7 40.5 240 6 3 5.4 3.0
7000 7.7 45.9 230 8 4 7.6 4.2 | 5.1 41.2 245 7 3 6.4 3.5
6750 8.5 47.3 235 8 4 10.9 6.0 | 5.6 42.1 250 5 3 8.6 4.7
6500 9.2 48.6 240 8 4 10.3 5.7 | 6.2 43.2 255 4 2 8.4 4.6
6250 10.0 50.0 245 7 4 9.2 5.1 | 6.8 44.2 270 3 1 6.8 3.7
6000 10.7 51.3 235 6 3 13.0 7.1 | 7.3 45.1 300 3 2 8.5 4.6
5750 12.0 53.6 240 5 3 23.0 12.6 | 8.2 46.8 315 3 2 16.1 8.8
5500 13.3 55.9 245 5 2 4.1 2.2 | 9.0 48.2 330 3 2 1.1 0.6
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
- National Weather Service
- Quad Cities, IA/IL Weather Forecast Office
- 9040 N Harrison Street
- Davenport Municipal Airport
- Davenport, IA 52806-7326
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- Page last modified: Sep 19th, 2023 19:10 UTC