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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 251237
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0636 MDT Thursday, April 25, 2024
This forecast is for Thursday, April 25, 2024:
If the trigger temperature of 70.5 F/21.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1271 ft/min (6.5 m/s)
Maximum height of thermals.................. 18599 ft MSL (13263 ft AGL)
Forecast maximum temperature................... 78.0 F/26.0 C
Time of trigger temperature.................... 1045 MDT
Time of overdevelopment........................ 1600 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 11658 ft MSL (6322 ft AGL)
Thermal soaring outlook for Friday 04/26....... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Little change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 39597 ft MSL (34261 ft AGL)
Wave soaring outlook for Friday 04/26.......... Poor
Remarks... Am fog and clouds, then sunny this afternoon...chances of rain and
storms increase this evening
Sunrise/Sunset.................... 06:06:31 / 19:48:07 MDT
Total possible sunshine........... 13 hr 41 min 36 sec (821 min 36 sec)
Altitude of sun at 12:57:19 MDT... 63.76 degrees
Upper air data from numerical model forecast valid on 04/25/2024 at 0600 MDT
Freezing level.................. 12849 ft MSL (7513 ft AGL)
Convective condensation level... 14860 ft MSL (9524 ft AGL)
Lifted condensation level....... 15996 ft MSL (10660 ft AGL)
Lifted index.................... -4.0
K index......................... +15.0
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 -54.7 -66.5 255 57 29 0.8 0.4 M M M M M
45000 -53.8 -64.8 250 57 29 -2.9 -1.6 M M M M M
40000 -57.7 -71.9 240 64 33 -2.6 -1.4 M M M M M
38000 -56.6 -69.9 235 65 34 4.6 2.5 M M M M M
36000 -53.5 -64.3 235 65 34 4.6 2.5 M M M M M
34000 -50.0 -58.0 235 64 33 7.8 4.3 M M M M M
32000 -45.3 -49.5 235 60 31 7.8 4.3 M M M M M
30000 -40.7 -41.3 235 55 28 7.8 4.3 34.8 94.6 7.0 M M
29000 -38.3 -36.9 230 52 27 7.8 4.3 34.0 93.1 6.4 M M
28000 -36.0 -32.8 230 49 25 7.8 4.3 33.3 91.9 6.0 M M
27000 -33.7 -28.7 230 46 24 6.8 3.7 32.5 90.5 5.5 M M
26000 -31.7 -25.1 225 44 22 6.8 3.7 31.3 88.3 4.5 M M
25000 -29.7 -21.5 220 42 21 6.8 3.7 30.2 86.3 3.7 M M
24000 -27.6 -17.7 220 40 21 7.6 4.2 29.2 84.6 2.9 M M
23000 -25.2 -13.4 220 39 20 8.2 4.5 28.5 83.4 2.4 M M
22000 -22.7 -8.9 220 38 19 8.2 4.5 28.0 82.4 2.0 M M
21000 -20.3 -4.5 220 36 19 7.8 4.3 27.5 81.4 1.5 M M
20000 -17.4 0.7 220 33 17 7.8 4.3 26.5 79.7 0.7 M M
19500 -16.2 2.8 215 32 16 7.8 4.3 26.2 79.2 0.4 M M
19000 -15.1 4.8 215 30 16 7.8 4.3 25.9 78.6 0.2 M M
18500 -13.9 7.0 215 29 15 7.5 4.1 25.5 78.0 -0.1 1251 6.4
18000 -12.8 9.0 220 27 14 7.6 4.2 25.2 77.3 -0.5 1203 6.1
17500 -11.7 10.9 220 26 13 7.6 4.2 24.8 76.6 -0.8 1155 5.9
17000 -10.6 12.9 220 24 12 7.6 4.2 24.4 75.9 -1.2 1107 5.6
16500 -9.5 14.9 225 23 12 7.7 4.2 24.1 75.3 -1.6 1059 5.4
16000 -8.3 17.1 225 21 11 8.1 4.5 23.8 74.8 -1.9 1009 5.1
15500 -7.1 19.2 230 19 10 8.0 4.4 23.5 74.3 -2.2 958 4.9
15000 -5.9 21.4 230 18 9 9.1 5.0 23.3 73.9 -2.4 906 4.6
14500 -4.5 23.9 235 17 9 9.0 4.9 23.2 73.7 -2.5 850 4.3
14000 -3.2 26.2 235 16 8 9.3 5.1 23.1 73.5 -2.6 795 4.0
13500 -1.8 28.8 240 15 8 9.3 5.1 23.0 73.4 -2.7 738 3.8
13000 -0.4 31.3 245 15 8 9.4 5.1 22.9 73.3 -2.8 682 3.5
12500 1.0 33.8 245 15 8 9.4 5.2 22.9 73.1 -2.9 625 3.2
12000 2.5 36.5 250 15 8 9.3 5.1 22.8 73.1 -2.9 568 2.9
11500 3.8 38.8 250 15 7 9.1 5.0 22.7 72.9 -3.0 511 2.6
11000 5.2 41.4 255 14 7 8.3 4.6 22.6 72.7 -3.1 455 2.3
10500 6.3 43.3 255 14 7 6.6 3.6 22.3 72.1 -3.5 407 2.1
10250 6.9 44.4 255 13 7 10.6 5.8 22.1 71.8 -3.7 383 1.9
10000 7.8 46.0 260 13 7 10.9 6.0 22.3 72.2 -3.5 348 1.8
9750 8.4 47.1 260 13 7 6.8 3.7 22.2 71.9 -3.7 323 1.6
9500 8.9 48.0 260 12 6 8.2 4.5 22.0 71.6 -3.8 299 1.5
9250 9.5 49.1 260 12 6 6.0 3.3 21.8 71.3 -4.0 275 1.4
9000 9.9 49.8 260 11 6 5.1 2.8 21.5 70.6 -4.4 257 1.3
8750 10.3 50.5 260 10 5 6.3 3.4 21.2 70.1 -4.7 237 1.2
8500 10.7 51.3 260 10 5 6.1 3.3 20.9 69.6 -5.1 217 1.1
8250 11.1 52.0 260 9 5 5.8 3.2 20.6 69.1 -5.4 197 1.0
8000 11.4 52.5 260 8 4 3.4 1.9 20.2 68.4 -5.8 180 0.9
7750 11.6 52.9 260 7 4 2.0 1.1 19.6 67.4 -6.4 168 0.9
7500 11.7 53.1 260 7 3 2.9 1.6 19.1 66.3 -7.1 158 0.8
7250 11.8 53.2 260 6 3 1.6 0.9 18.5 65.4 -7.7 147 0.7
7000 11.7 53.1 260 5 3 -0.3 -0.2 17.8 64.1 -8.5 141 0.7
6750 11.6 52.9 260 5 3 -2.4 -1.3 17.0 62.6 -9.4 139 0.7
6500 11.2 52.2 260 4 2 -3.7 -2.0 16.0 60.8 -10.5 142 0.7
6250 10.8 51.4 265 4 2 -4.4 -2.4 15.0 58.9 -11.7 146 0.7
6000 10.4 50.7 265 3 2 -6.4 -3.5 13.8 56.8 -12.9 152 0.8
5750 10.0 50.0 265 3 2 -2.5 -1.3 12.7 54.8 -14.1 157 0.8
5500 9.9 49.8 245 3 1 0.1 0.0 11.9 53.5 -14.9 151 0.8
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/25/2024 at 0900 MDT | 04/25/2024 at 1200 MDT
|
CAPE... +92.5 LI... +0.6 | CAPE... +94.2 LI... -0.4
CINH... -132.7 K Index... +6.4 | CINH... -9.6 K Index... +10.0
|
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 -53.6 -64.5 255 54 28 1.1 0.6 | -52.5 -62.5 255 52 27 2.3 1.2
45000 -52.3 -62.1 240 57 29 -4.0 -2.2 | -49.5 -57.1 240 59 30 -4.4 -2.4
40000 -57.5 -71.5 230 61 31 -3.5 -1.9 | -55.5 -67.9 220 62 32 -4.0 -2.2
38000 -56.7 -70.1 230 63 33 4.7 2.6 | -55.7 -68.3 215 65 33 3.0 1.7
36000 -53.5 -64.3 230 67 34 4.7 2.6 | -53.7 -64.7 215 67 35 3.0 1.7
34000 -50.1 -58.2 230 68 35 7.5 4.1 | -51.0 -59.8 220 68 35 7.8 4.3
32000 -45.6 -50.1 230 63 33 7.5 4.1 | -46.3 -51.3 220 67 34 7.9 4.3
30000 -41.0 -41.8 225 59 30 7.9 4.3 | -41.5 -42.7 220 64 33 7.7 4.3
29000 -38.6 -37.5 225 56 29 7.9 4.3 | -39.2 -38.6 220 61 31 7.7 4.2
28000 -36.3 -33.3 225 54 28 7.9 4.3 | -36.9 -34.4 220 58 30 7.7 4.2
27000 -33.9 -29.0 225 51 26 7.4 4.0 | -34.6 -30.3 220 55 28 7.6 4.2
26000 -31.7 -25.1 220 50 26 7.3 4.0 | -32.3 -26.1 220 53 27 7.6 4.1
25000 -29.5 -21.1 220 49 25 7.3 4.0 | -30.0 -22.0 215 50 26 7.6 4.2
24000 -27.3 -17.1 220 48 25 6.9 3.8 | -27.7 -17.9 215 48 24 7.2 4.0
23000 -25.4 -13.7 220 46 24 6.4 3.5 | -25.8 -14.4 215 44 23 6.3 3.5
22000 -23.5 -10.3 225 43 22 6.4 3.5 | -23.9 -11.0 220 41 21 6.3 3.5
21000 -21.5 -6.7 225 41 21 8.0 4.4 | -22.0 -7.6 220 38 20 7.1 3.9
20000 -19.1 -2.4 225 38 20 8.2 4.5 | -19.8 -3.6 220 33 17 7.5 4.1
19500 -17.2 1.0 225 36 18 8.2 4.5 | -18.1 -0.6 225 29 15 7.5 4.1
19000 -16.0 3.2 225 34 18 8.3 4.5 | -17.0 1.4 225 27 14 7.5 4.1
18500 -14.8 5.4 225 32 17 7.6 4.2 | -15.8 3.6 225 25 13 8.4 4.6
18000 -13.6 7.5 225 30 15 7.7 4.2 | -14.6 5.7 220 23 12 8.4 4.6
17500 -12.5 9.5 225 27 14 7.9 4.3 | -13.4 7.9 220 21 11 8.6 4.7
17000 -11.3 11.7 225 24 13 8.0 4.4 | -12.0 10.4 220 20 10 8.9 4.9
16500 -10.1 13.8 225 22 11 8.0 4.4 | -10.7 12.7 220 19 10 8.9 4.9
16000 -8.9 16.0 225 19 10 8.3 4.5 | -9.4 15.1 215 17 9 9.1 5.0
15500 -7.7 18.1 220 17 9 8.2 4.5 | -8.0 17.6 215 16 8 9.1 5.0
15000 -6.4 20.5 220 16 8 8.9 4.9 | -6.6 20.1 210 15 8 9.2 5.1
14500 -5.1 22.8 220 14 7 8.9 4.9 | -5.3 22.5 210 15 8 9.2 5.1
14000 -3.8 25.2 220 13 6 9.2 5.0 | -3.9 25.0 205 14 7 8.9 4.9
13500 -2.4 27.7 220 12 6 9.2 5.1 | -2.6 27.3 205 13 7 8.8 4.8
13000 -1.0 30.2 225 12 6 8.8 4.8 | -1.3 29.7 200 11 6 8.9 4.9
12500 0.2 32.4 225 11 6 8.6 4.7 | 0.1 32.2 200 11 6 9.1 5.0
12000 1.5 34.7 225 10 5 8.8 4.8 | 1.4 34.5 200 11 6 9.1 5.0
11500 2.8 37.0 230 9 5 9.0 4.9 | 2.8 37.0 195 10 5 9.0 4.9
11000 4.2 39.6 230 9 4 8.4 4.6 | 4.1 39.4 195 10 5 8.5 4.6
10500 5.3 41.5 235 8 4 6.8 3.7 | 5.2 41.4 190 9 5 6.3 3.5
10250 5.9 42.6 235 8 4 10.5 5.8 | 5.8 42.4 190 8 4 10.1 5.5
10000 6.8 44.2 240 8 4 11.7 6.4 | 6.7 44.1 190 7 4 12.2 6.7
9750 7.5 45.5 245 8 4 8.3 4.6 | 7.4 45.3 190 7 4 9.0 5.0
9500 8.2 46.8 245 8 4 9.5 5.2 | 8.1 46.6 190 7 3 8.6 4.7
9250 8.9 48.0 250 8 4 7.4 4.1 | 8.7 47.7 185 6 3 9.4 5.1
9000 9.3 48.7 250 8 4 7.1 3.9 | 9.5 49.1 185 5 3 10.2 5.6
8750 10.0 50.0 255 8 4 8.7 4.8 | 10.2 50.4 185 5 2 9.7 5.3
8500 10.6 51.1 255 8 4 8.4 4.6 | 10.9 51.6 185 4 2 9.4 5.1
8250 11.2 52.2 255 8 4 8.1 4.4 | 11.6 52.9 185 4 2 9.3 5.1
8000 11.7 53.1 255 8 4 6.1 3.4 | 12.2 54.0 180 4 2 8.4 4.6
7750 12.1 53.8 255 7 4 5.5 3.0 | 12.9 55.2 180 3 2 9.1 5.0
7500 12.5 54.5 255 7 4 6.5 3.6 | 13.6 56.5 175 3 2 10.4 5.7
7250 12.9 55.2 255 7 3 4.5 2.5 | 14.4 57.9 175 3 1 9.2 5.1
7000 13.1 55.6 250 6 3 1.5 0.8 | 15.0 59.0 170 2 1 7.3 4.0
6750 13.1 55.6 245 6 3 0.0 0.0 | 15.5 59.9 165 2 1 9.7 5.3
6500 13.0 55.4 240 5 3 -0.6 -0.3 | 16.4 61.5 165 2 1 12.3 6.7
6250 12.8 55.0 235 4 2 -0.2 -0.1 | 17.2 63.0 160 2 1 10.7 5.9
6000 12.7 54.9 230 4 2 -1.1 -0.6 | 18.0 64.4 155 1 1 10.0 5.5
5750 12.6 54.7 220 4 2 3.2 1.8 | 18.7 65.7 145 1 1 9.9 5.4
5500 13.2 55.8 220 3 2 14.1 7.7 | 19.6 67.3 150 1 1 16.5 9.1
04/25/2024 at 1500 MDT | 04/25/2024 at 1800 MDT
|
CAPE... +146.7 LI... -0.4 | CAPE... +251.3 LI... -0.4
CINH... -11.4 K Index... +17.0 | CINH... -101.5 K Index... +23.1
|
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 -51.9 -61.4 250 49 25 2.6 1.4 | -51.8 -61.2 245 44 23 2.7 1.5
45000 -48.3 -54.9 245 56 29 -2.4 -1.3 | -48.0 -54.4 245 43 22 -0.5 -0.3
40000 -52.4 -62.3 225 60 31 -2.6 -1.4 | -49.2 -56.6 230 45 23 -0.8 -0.4
38000 -52.7 -62.9 215 62 32 1.0 0.5 | -49.8 -57.6 220 46 24 -1.2 -0.6
36000 -52.1 -61.8 215 64 33 1.0 0.5 | -50.5 -58.9 210 48 25 -1.2 -0.6
34000 -50.9 -59.6 210 66 34 6.8 3.7 | -50.8 -59.4 200 50 26 4.8 2.6
32000 -47.0 -52.6 210 66 34 6.5 3.6 | -48.4 -55.1 200 38 20 4.1 2.3
30000 -43.1 -45.6 210 65 33 6.6 3.6 | -45.5 -49.9 195 28 15 9.1 5.0
29000 -40.6 -41.1 210 57 30 6.6 3.6 | -43.0 -45.4 195 27 14 8.6 4.7
28000 -38.6 -37.5 210 52 27 6.7 3.6 | -39.8 -39.6 190 26 14 8.6 4.7
27000 -36.6 -33.9 210 46 24 7.7 4.2 | -37.2 -35.0 190 25 13 8.7 4.8
26000 -34.2 -29.6 210 41 21 8.1 4.4 | -34.6 -30.3 190 26 13 8.8 4.8
25000 -31.8 -25.2 210 35 18 8.1 4.4 | -31.9 -25.4 190 26 14 8.8 4.8
24000 -29.4 -20.9 205 30 16 8.2 4.5 | -29.3 -20.7 190 27 14 8.8 4.8
23000 -26.9 -16.4 205 28 14 8.4 4.6 | -26.7 -16.1 190 27 14 8.6 4.7
22000 -24.5 -12.1 205 26 13 8.4 4.6 | -24.2 -11.6 185 26 13 8.6 4.7
21000 -22.0 -7.6 205 23 12 8.2 4.5 | -21.6 -6.9 185 26 13 8.3 4.6
20000 -19.6 -3.3 205 21 11 8.1 4.4 | -19.2 -2.6 185 24 12 8.2 4.5
19500 -18.4 -1.1 205 21 11 8.1 4.5 | -18.0 -0.4 180 23 12 8.2 4.5
19000 -17.2 1.0 200 20 10 8.1 4.5 | -16.8 1.8 180 22 11 8.2 4.5
18500 -16.0 3.2 200 19 10 8.3 4.6 | -15.6 3.9 180 21 11 8.2 4.5
18000 -14.7 5.5 200 18 9 8.5 4.7 | -14.4 6.1 180 20 10 8.0 4.4
17500 -13.5 7.7 200 18 9 8.5 4.7 | -13.2 8.2 180 19 10 8.1 4.4
17000 -12.2 10.0 195 17 9 9.1 5.0 | -12.0 10.4 180 18 9 8.2 4.5
16500 -10.8 12.6 195 16 8 9.1 5.0 | -10.8 12.6 180 17 9 8.2 4.5
16000 -9.5 14.9 195 15 8 9.3 5.1 | -9.6 14.7 180 16 8 8.3 4.6
15500 -8.1 17.4 190 15 8 9.3 5.1 | -8.4 16.9 180 15 8 8.5 4.6
15000 -6.0 21.2 190 14 7 9.6 5.3 | -6.5 20.3 180 14 7 8.7 4.7
14500 -4.6 23.7 190 13 7 9.6 5.3 | -5.2 22.6 185 13 7 8.7 4.8
14000 -3.1 26.4 185 12 6 9.5 5.2 | -4.0 24.8 185 11 6 8.7 4.8
13500 -1.7 28.9 185 12 6 9.5 5.2 | -2.7 27.1 185 10 5 8.8 4.8
13000 -0.3 31.5 185 11 6 9.5 5.2 | -1.4 29.5 185 9 5 8.7 4.8
12500 1.1 34.0 185 10 5 9.5 5.2 | -0.1 31.8 190 7 4 8.5 4.7
12000 2.5 36.5 180 9 5 9.5 5.2 | 1.2 34.2 200 6 3 8.5 4.7
11500 3.9 39.0 180 8 4 9.3 5.1 | 2.4 36.3 210 4 2 8.1 4.4
11000 5.3 41.5 180 8 4 9.2 5.0 | 3.6 38.5 240 3 2 8.1 4.4
10500 6.6 43.9 175 6 3 8.4 4.6 | 4.5 40.1 280 3 2 4.9 2.7
10250 7.3 45.1 170 6 3 10.2 5.6 | 5.0 41.0 295 4 2 7.9 4.4
10000 8.1 46.6 170 6 3 11.1 6.1 | 5.7 42.3 305 5 3 10.7 5.9
9750 8.8 47.8 170 5 3 9.5 5.2 | 6.4 43.5 310 6 3 7.8 4.3
9500 9.5 49.1 165 5 2 9.0 4.9 | 6.9 44.4 310 8 4 6.3 3.5
9250 10.2 50.4 165 4 2 9.4 5.1 | 7.4 45.3 310 9 5 7.0 3.8
9000 10.9 51.6 160 4 2 9.8 5.4 | 8.0 46.4 310 10 5 8.9 4.9
8750 11.6 52.9 160 4 2 9.7 5.3 | 8.6 47.5 315 11 6 8.0 4.4
8500 12.4 54.3 155 3 2 9.6 5.3 | 9.1 48.4 310 12 6 6.3 3.5
8250 13.1 55.6 150 3 2 9.5 5.2 | 9.6 49.3 310 14 7 6.1 3.3
8000 13.8 56.8 140 3 1 9.8 5.4 | 10.1 50.2 305 15 8 8.8 4.8
7750 14.5 58.1 145 3 2 9.8 5.4 | 10.8 51.4 310 16 8 9.5 5.2
7500 15.2 59.4 135 3 1 9.3 5.1 | 11.4 52.5 305 17 9 6.9 3.8
7250 15.9 60.6 130 3 1 9.6 5.3 | 11.9 53.4 305 18 9 8.6 4.7
7000 16.6 61.9 120 2 1 7.4 4.0 | 12.5 54.5 305 19 10 4.7 2.6
6750 17.1 62.8 105 2 1 8.6 4.7 | 12.7 54.9 305 19 10 6.8 3.8
6500 17.9 64.2 100 2 1 11.3 6.2 | 13.5 56.3 305 18 9 12.1 6.7
6250 18.7 65.7 095 2 1 10.5 5.8 | 14.3 57.7 305 18 9 10.4 5.7
6000 19.4 66.9 085 2 1 9.7 5.3 | 15.1 59.2 305 17 9 8.5 4.7
5750 20.3 68.5 070 2 1 14.9 8.2 | 15.7 60.3 305 17 9 10.7 5.9
5500 21.8 71.2 060 2 1 25.3 13.9 | 16.8 62.2 305 14 7 18.3 10.1
________________________________________________________________________________
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 near the old Stapleton
Airport site in Denver, Colorado at
North Latitude: 39 deg 46 min 5.016 sec
West Longitude: 104 deg 52 min 9.984 sec
Elevation: 5285 feet (1611 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.
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
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