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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 241307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Wednesday, April 24, 2024
This forecast is for Wednesday, April 24, 2024:
If the trigger temperature of 72.8 F/22.7 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1507 ft/min (7.7 m/s)
Maximum height of thermals.................. 20530 ft MSL (15710 ft AGL)
Forecast maximum temperature................... 83.0 F/28.8 C
Time of trigger temperature.................... 1045 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................. 16834 ft MSL (12014 ft AGL)
Thermal soaring outlook for Thursday 04/25..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:23:36 / 20:00:40 MDT
Total possible sunshine........... 13 hr 37 min 4 sec (817 min 4 sec)
Altitude of sun at 13:12:08 MDT... 63.96 degrees
Upper air data from rawinsonde observation taken on 04/24/2024 at 0600 MDT
Freezing level.................. 13006 ft MSL (8186 ft AGL)
Convective condensation level... 17281 ft MSL (12461 ft AGL)
Lifted condensation level....... 18677 ft MSL (13857 ft AGL)
Lifted index.................... -0.2
K index......................... +12.6
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 -54.0 -65.2 260 72 37 4.2 2.3 109.4 228.8 46.4 M M
45000 -54.5 -66.1 265 58 30 -6.6 -3.6 82.6 180.7 33.4 M M
40000 -59.3 -74.7 250 74 38 -3.7 -2.0 52.0 125.6 15.6 M M
38000 -56.7 -70.1 245 74 38 5.7 3.1 47.3 117.1 12.8 M M
36000 -52.9 -63.2 245 67 34 6.8 3.7 44.1 111.4 11.0 M M
34000 -48.8 -55.8 245 61 31 7.7 4.2 41.6 106.9 9.5 M M
32000 -44.1 -47.4 250 60 31 7.4 4.1 40.2 104.3 8.7 M M
30000 -39.1 -38.4 260 44 22 4.8 2.6 38.1 100.6 7.3 M M
29000 -37.2 -35.0 260 41 21 7.1 3.9 36.7 98.0 6.3 M M
28000 -34.8 -30.6 255 41 21 8.4 4.6 36.0 96.8 5.9 M M
27000 -32.3 -26.1 255 39 20 8.7 4.8 35.5 95.8 5.6 M M
26000 -29.7 -21.5 250 36 19 9.0 5.0 35.1 95.1 5.3 M M
25000 -28.2 -18.8 240 43 22 3.8 2.1 33.2 91.8 3.8 M M
24000 -25.7 -14.3 240 42 22 9.6 5.2 32.8 91.0 3.5 M M
23000 -23.2 -9.8 240 41 21 7.2 3.9 32.3 90.1 3.2 M M
22000 -20.7 -5.3 240 38 20 8.4 4.6 31.7 89.1 2.8 M M
21000 -19.0 -2.2 240 36 19 -2.1 -1.2 30.2 86.3 1.5 M M
20000 -18.3 -0.9 220 28 15 4.9 2.7 27.6 81.7 -0.7 1472 7.5
19500 -17.5 0.5 215 28 14 7.7 4.2 26.9 80.4 -1.3 1433 7.3
19000 -16.2 2.8 210 25 13 9.7 5.3 26.7 80.0 -1.5 1380 7.0
18500 -15.0 5.0 210 23 12 6.3 3.5 26.5 79.6 -1.7 1328 6.7
18000 -14.0 6.8 220 16 8 6.9 3.8 26.0 78.8 -2.2 1283 6.5
17500 -13.0 8.6 220 15 8 6.7 3.7 25.5 77.9 -2.7 1239 6.3
17000 -11.8 10.8 220 17 9 10.2 5.6 25.3 77.5 -3.0 1188 6.0
16500 -9.8 14.4 220 20 10 8.6 4.7 25.1 77.1 -3.2 1106 5.6
16000 -8.4 16.9 225 22 11 9.6 5.2 25.0 77.1 -3.3 1049 5.3
15500 -6.9 19.6 220 21 11 9.6 5.3 25.1 77.1 -3.3 991 5.0
15000 -5.5 22.1 220 23 12 9.6 5.3 25.0 77.1 -3.3 934 4.7
14500 -4.1 24.6 230 21 11 9.6 5.3 25.0 77.0 -3.3 876 4.5
14000 -2.7 27.1 235 20 10 9.6 5.3 25.0 77.0 -3.4 818 4.2
13500 -1.2 29.8 240 22 11 9.6 5.3 25.0 77.0 -3.4 761 3.9
13000 0.2 32.4 240 23 12 9.6 5.3 25.0 76.9 -3.5 703 3.6
12500 1.6 34.9 255 21 11 9.6 5.3 24.9 76.8 -3.5 646 3.3
12000 3.1 37.6 255 21 11 9.6 5.3 24.9 76.7 -3.6 588 3.0
11500 4.5 40.1 255 19 10 9.8 5.4 24.8 76.6 -3.7 530 2.7
11000 5.8 42.4 250 16 8 7.3 4.0 24.6 76.3 -3.9 477 2.4
10500 6.8 44.2 255 20 10 6.3 3.5 24.1 75.4 -4.4 432 2.2
10250 7.3 45.1 255 22 11 7.0 3.9 23.9 75.0 -4.6 410 2.1
10000 7.9 46.2 255 22 11 8.1 4.4 23.7 74.7 -4.8 385 2.0
9750 8.5 47.3 255 20 10 8.1 4.4 23.6 74.5 -4.9 360 1.8
9500 9.1 48.4 255 18 9 8.1 4.4 23.5 74.3 -5.1 334 1.7
9250 9.7 49.5 250 20 10 8.1 4.4 23.4 74.0 -5.2 309 1.6
9000 10.3 50.5 240 17 9 8.1 4.4 23.2 73.8 -5.3 283 1.4
8750 10.9 51.6 240 16 8 8.1 4.4 23.1 73.6 -5.5 258 1.3
8500 11.5 52.7 245 14 7 8.1 4.4 23.0 73.3 -5.6 232 1.2
8250 12.1 53.8 245 13 7 8.1 4.4 22.8 73.1 -5.8 207 1.1
8000 12.7 54.9 245 8 4 8.1 4.4 22.7 72.9 -5.9 181 0.9
7750 13.3 55.9 240 6 3 8.1 4.5 22.6 72.6 -6.0 156 0.8
7500 13.9 57.0 200 4 2 8.1 4.4 22.4 72.4 -6.2 130 0.7
7250 14.5 58.1 160 6 3 8.3 4.5 22.3 72.2 -6.3 105 0.5
7000 15.1 59.2 150 9 5 6.0 3.3 22.1 71.9 -6.5 81 0.4
6750 15.4 59.7 145 11 6 5.0 2.7 21.8 71.2 -6.9 63 0.3
6500 15.8 60.4 140 13 7 6.2 3.4 21.5 70.6 -7.3 43 0.2
6250 16.2 61.2 140 15 8 5.8 3.2 21.2 70.1 -7.6 23 0.1
6000 16.6 61.9 135 18 9 6.2 3.4 20.9 69.6 -7.9 3 0.0
5750 17.1 62.8 135 19 10 5.2 2.9 20.6 69.1 -8.3 M M
5500 17.5 63.5 130 17 9 9.1 5.0 20.3 68.6 -8.6 M M
5250 17.9 64.2 125 15 8 -5.2 -2.9 20.1 68.1 -8.9 M M
5000 16.0 60.8 120 11 6 -43.8 -24.0 17.5 63.4 -11.5 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/24/2024 at 0900 MDT | 04/24/2024 at 1200 MDT
|
CAPE... 0.0 LI... +1.5 | CAPE... 0.0 LI... +2.3
CINH... -0.0 K Index... +14.5 | CINH... -0.0 K Index... +13.8
|
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 -68.1 260 51 26 2.6 1.4 | -55.5 -67.9 255 53 27 2.2 1.2
45000 -52.4 -62.3 260 58 30 -4.1 -2.3 | -53.0 -63.4 255 62 32 -4.2 -2.3
40000 -58.2 -72.8 255 69 36 -3.5 -1.9 | -59.1 -74.4 255 70 36 -3.9 -2.1
38000 -56.4 -69.5 255 68 35 5.2 2.8 | -56.9 -70.4 255 71 36 5.8 3.2
36000 -53.3 -63.9 255 66 34 5.2 2.8 | -53.4 -64.1 255 70 36 5.8 3.2
34000 -49.5 -57.1 260 63 33 8.1 4.4 | -49.4 -56.9 250 68 35 7.8 4.3
32000 -44.7 -48.5 255 59 30 8.1 4.4 | -44.7 -48.5 250 63 32 7.8 4.3
30000 -40.1 -40.2 255 53 27 7.1 3.9 | -39.9 -39.8 245 58 30 8.2 4.5
29000 -37.9 -36.2 255 47 24 7.1 3.9 | -37.5 -35.5 250 55 28 8.2 4.5
28000 -35.8 -32.4 255 42 22 7.1 3.9 | -35.0 -31.0 250 52 27 8.2 4.5
27000 -33.6 -28.5 255 38 20 8.4 4.6 | -32.6 -26.7 250 49 25 7.4 4.1
26000 -30.5 -22.9 250 38 20 8.3 4.5 | -29.8 -21.6 250 44 23 7.5 4.1
25000 -28.0 -18.4 250 39 20 8.3 4.5 | -27.6 -17.7 245 40 20 7.5 4.1
24000 -25.6 -14.1 245 39 20 7.4 4.0 | -25.3 -13.5 245 37 19 7.5 4.1
23000 -23.4 -10.1 245 38 20 7.4 4.1 | -23.1 -9.6 245 38 19 7.5 4.1
22000 -21.2 -6.2 245 37 19 7.4 4.0 | -20.8 -5.4 245 38 20 7.5 4.1
21000 -19.2 -2.6 240 35 18 5.9 3.2 | -18.6 -1.5 245 37 19 7.1 3.9
20000 -17.5 0.5 240 32 16 5.8 3.2 | -16.5 2.3 245 35 18 7.1 3.9
19500 -16.6 2.1 235 30 16 5.8 3.2 | -15.4 4.3 245 34 18 7.0 3.9
19000 -15.7 3.7 235 28 15 5.9 3.2 | -14.4 6.1 245 33 17 6.8 3.7
18500 -14.8 5.4 235 27 14 6.2 3.4 | -13.5 7.7 245 31 16 5.3 2.9
18000 -13.9 7.0 230 26 13 6.1 3.4 | -12.7 9.1 240 29 15 5.4 3.0
17500 -13.0 8.6 230 24 13 7.4 4.1 | -11.9 10.6 235 27 14 5.4 2.9
17000 -11.9 10.6 230 24 12 7.7 4.2 | -11.2 11.8 235 25 13 5.5 3.0
16500 -10.8 12.6 230 23 12 8.0 4.4 | -10.4 13.3 230 23 12 6.2 3.4
16000 -9.5 14.9 230 22 11 8.7 4.8 | -9.3 15.3 230 22 11 7.6 4.2
15500 -8.2 17.2 230 21 11 8.7 4.8 | -8.2 17.2 225 20 11 7.6 4.2
15000 -6.9 19.6 230 21 11 9.2 5.0 | -7.0 19.4 225 19 10 8.0 4.4
14500 -5.5 22.1 230 20 10 9.1 5.0 | -5.9 21.4 225 18 9 7.9 4.3
14000 -4.2 24.4 230 19 10 9.3 5.1 | -4.7 23.5 220 17 9 8.7 4.8
13500 -2.8 27.0 230 18 9 9.3 5.1 | -3.4 25.9 220 16 8 8.7 4.8
13000 -1.4 29.5 230 17 9 9.0 4.9 | -2.1 28.2 220 15 8 9.1 5.0
12500 -0.1 31.8 235 17 9 9.0 4.9 | -0.7 30.7 220 15 8 9.2 5.1
12000 1.2 34.2 235 16 8 8.5 4.7 | 0.6 33.1 225 14 7 9.4 5.1
11500 2.4 36.3 235 15 8 8.4 4.6 | 2.0 35.6 225 14 7 9.5 5.2
11000 3.7 38.7 240 15 8 7.3 4.0 | 3.4 38.1 225 14 7 8.2 4.5
10500 4.7 40.5 240 15 8 6.1 3.4 | 4.6 40.3 230 13 7 6.7 3.7
10250 5.2 41.4 240 15 7 9.9 5.4 | 5.2 41.4 230 12 6 11.7 6.4
10000 6.1 43.0 245 14 7 10.3 5.6 | 6.2 43.2 230 13 7 12.9 7.1
9750 6.6 43.9 240 13 7 6.5 3.6 | 6.9 44.4 230 13 6 8.4 4.6
9500 7.2 45.0 240 13 7 8.0 4.4 | 7.6 45.7 230 12 6 10.1 5.5
9250 7.7 45.9 240 12 6 5.7 3.1 | 8.3 46.9 230 12 6 7.9 4.3
9000 8.1 46.6 245 12 6 5.8 3.2 | 9.6 49.3 235 11 6 10.4 5.7
8750 8.6 47.5 240 11 6 7.7 4.2 | 10.4 50.7 235 11 5 10.0 5.5
8500 9.8 49.6 235 10 5 6.0 3.3 | 11.1 52.0 230 10 5 9.5 5.2
8250 10.1 50.2 235 10 5 4.7 2.6 | 11.8 53.2 235 10 5 9.3 5.1
8000 10.5 50.9 235 9 5 6.9 3.8 | 12.6 54.7 240 9 5 10.3 5.6
7750 11.1 52.0 230 8 4 7.9 4.3 | 13.3 55.9 235 9 5 10.7 5.9
7500 11.6 52.9 220 7 4 5.8 3.2 | 14.1 57.4 235 9 5 9.4 5.1
7250 12.0 53.6 220 7 4 4.3 2.3 | 14.8 58.6 240 9 5 8.5 4.6
7000 12.4 54.3 220 7 3 8.6 4.7 | 15.5 59.9 240 9 4 10.6 5.8
6750 13.2 55.8 210 6 3 10.1 5.5 | 16.3 61.3 240 9 4 11.5 6.3
6500 13.8 56.8 200 6 3 7.4 4.1 | 17.1 62.8 240 8 4 10.7 5.9
6250 14.3 57.7 195 5 3 6.8 3.7 | 18.0 64.4 245 8 4 11.4 6.3
6000 14.9 58.8 190 5 2 8.1 4.4 | 18.8 65.8 245 8 4 8.1 4.4
5750 15.6 60.1 190 5 3 14.1 7.8 | 19.3 66.7 240 8 4 12.5 6.9
5500 17.2 63.0 180 3 2 27.8 15.2 | 22.3 72.1 250 7 4 87.2 47.8
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
04/24/2024 at 1500 MDT | 04/24/2024 at 1800 MDT
|
CAPE... +0.5 LI... +1.6 | CAPE... +0.7 LI... +0.8
CINH... -0.1 K Index... +16.5 | CINH... -0.7 K Index... +16.0
|
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 -56.0 -68.8 260 55 28 1.8 1.0 | -55.6 -68.1 260 53 27 1.7 0.9
45000 -53.8 -64.8 255 64 33 -3.6 -2.0 | -53.6 -64.5 255 64 33 -3.4 -1.9
40000 -59.0 -74.2 250 73 38 -3.3 -1.8 | -58.5 -73.3 240 74 38 -3.0 -1.7
38000 -56.7 -70.1 245 74 38 5.9 3.3 | -56.3 -69.3 240 75 39 5.7 3.1
36000 -53.1 -63.6 245 74 38 5.9 3.3 | -52.9 -63.2 240 75 39 5.7 3.1
34000 -49.1 -56.4 245 71 37 7.6 4.2 | -49.0 -56.2 240 73 38 7.5 4.1
32000 -44.6 -48.3 245 66 34 7.6 4.2 | -44.5 -48.1 240 70 36 7.5 4.1
30000 -39.9 -39.8 245 60 31 8.1 4.4 | -39.9 -39.8 240 64 33 7.7 4.2
29000 -37.4 -35.3 245 57 29 8.1 4.4 | -37.6 -35.7 240 60 31 7.7 4.2
28000 -35.0 -31.0 245 54 28 8.1 4.4 | -35.4 -31.7 240 55 28 7.7 4.2
27000 -32.0 -25.6 245 50 26 7.7 4.2 | -33.1 -27.6 240 51 26 7.7 4.3
26000 -29.7 -21.5 240 46 24 7.7 4.2 | -30.1 -22.2 235 46 24 7.7 4.2
25000 -27.4 -17.3 240 42 22 7.7 4.2 | -27.8 -18.0 235 42 22 7.7 4.2
24000 -25.1 -13.2 240 40 20 7.4 4.1 | -25.5 -13.9 235 39 20 7.4 4.0
23000 -22.9 -9.2 240 39 20 7.5 4.1 | -23.3 -9.9 235 36 19 7.4 4.1
22000 -20.7 -5.3 240 38 20 7.5 4.1 | -21.1 -6.0 235 34 18 7.4 4.1
21000 -18.5 -1.3 240 36 18 6.9 3.8 | -19.0 -2.2 230 31 16 6.7 3.7
20000 -16.5 2.3 235 32 16 6.9 3.8 | -17.1 1.2 230 27 14 6.8 3.7
19500 -15.4 4.3 235 30 15 6.9 3.8 | -16.1 3.0 225 25 13 6.8 3.7
19000 -14.4 6.1 235 28 14 6.8 3.7 | -15.1 4.8 225 23 12 6.9 3.8
18500 -13.5 7.7 235 26 13 5.9 3.3 | -14.0 6.8 225 22 11 7.8 4.3
18000 -12.6 9.3 235 25 13 6.0 3.3 | -12.9 8.8 220 21 11 7.8 4.3
17500 -11.7 10.9 230 23 12 6.9 3.8 | -11.8 10.8 220 20 10 8.0 4.4
17000 -10.7 12.7 225 22 11 7.1 3.9 | -10.6 12.9 215 20 10 8.1 4.4
16500 -9.7 14.5 225 21 11 7.7 4.2 | -9.4 15.1 215 19 10 8.4 4.6
16000 -8.4 16.9 220 20 10 8.8 4.8 | -8.0 17.6 215 19 10 9.3 5.1
15500 -7.1 19.2 220 20 10 8.8 4.8 | -6.6 20.1 210 19 10 9.3 5.1
15000 -5.8 21.6 220 19 10 9.4 5.1 | -5.2 22.6 210 19 10 9.7 5.3
14500 -4.4 24.1 220 19 10 9.3 5.1 | -3.8 25.2 210 19 10 9.7 5.3
14000 -3.0 26.6 215 18 9 9.2 5.1 | -2.3 27.9 210 19 10 9.4 5.2
13500 -1.6 29.1 215 17 9 9.2 5.1 | -0.9 30.4 210 19 10 9.4 5.2
13000 -0.2 31.6 215 17 9 9.2 5.1 | 0.5 32.9 210 19 10 9.3 5.1
12500 1.2 34.2 215 16 8 9.2 5.1 | 1.9 35.4 210 18 9 9.2 5.0
12000 2.5 36.5 220 16 8 9.2 5.0 | 3.3 37.9 210 18 9 9.2 5.1
11500 3.9 39.0 220 15 8 9.1 5.0 | 4.7 40.5 215 18 9 9.2 5.0
11000 5.3 41.5 220 14 7 8.4 4.6 | 6.0 42.8 215 17 9 8.5 4.7
10500 6.4 43.5 225 13 6 7.1 3.9 | 7.2 45.0 215 16 8 7.1 3.9
10250 7.0 44.6 230 12 6 11.0 6.0 | 7.8 46.0 215 15 8 10.9 6.0
10000 8.0 46.4 230 13 7 12.1 6.6 | 8.8 47.8 215 16 8 11.4 6.2
9750 8.7 47.7 230 13 7 9.0 4.9 | 9.4 48.9 220 15 8 8.0 4.4
9500 10.2 50.4 230 12 6 9.5 5.2 | 10.1 50.2 220 15 8 8.7 4.8
9250 10.9 51.6 235 11 6 9.9 5.4 | 10.7 51.3 220 14 7 9.1 5.0
9000 11.7 53.1 235 12 6 10.1 5.6 | 12.1 53.8 220 15 8 9.3 5.1
8750 12.4 54.3 235 12 6 10.1 5.6 | 12.9 55.2 220 14 7 9.5 5.2
8500 13.2 55.8 235 12 6 9.8 5.4 | 13.6 56.5 225 14 7 9.2 5.1
8250 13.9 57.0 240 12 6 9.7 5.3 | 14.2 57.6 225 14 7 9.2 5.1
8000 14.6 58.3 240 11 6 10.1 5.5 | 14.9 58.8 225 13 7 9.6 5.3
7750 15.4 59.7 240 12 6 10.4 5.7 | 15.7 60.3 225 13 7 9.8 5.4
7500 16.2 61.2 240 12 6 9.5 5.2 | 16.4 61.5 225 13 7 9.3 5.1
7250 16.8 62.2 245 11 6 8.7 4.8 | 17.1 62.8 230 13 7 8.8 4.8
7000 17.5 63.5 245 11 6 10.4 5.7 | 17.8 64.0 230 13 7 9.8 5.4
6750 18.4 65.1 245 11 6 11.3 6.2 | 18.5 65.3 230 13 7 10.4 5.7
6500 19.2 66.6 240 11 6 11.0 6.1 | 19.3 66.7 225 12 6 10.4 5.7
6250 20.0 68.0 245 11 6 12.0 6.6 | 20.1 68.2 230 12 6 11.3 6.2
6000 20.9 69.6 250 10 5 8.0 4.4 | 20.9 69.6 235 12 6 8.5 4.6
5750 21.4 70.5 245 10 5 11.9 6.5 | 21.5 70.7 230 11 6 9.0 4.9
5500 24.5 76.1 250 9 5 91.0 49.9 | 23.2 73.8 235 10 5 50.0 27.5
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
- Paducah, KY Weather Forecast Office
- 8250 Kentucky Highway 3520
- West Paducah, KY 42086-9762
- 270-744-6440
- Page Author: PAH Webmaster
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- Page last modified: Sep 19th, 2023 19:10 UTC