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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 150116
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1915 MDT Sunday, April 14, 2024
This forecast is for Monday, April 15, 2024:
If the trigger temperature of 70.1 F/21.2 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 782 ft/min (4.0 m/s)
Maximum height of thermals.................. 14291 ft MSL (8996 ft AGL)
Forecast maximum temperature................... 76.0 F/24.9 C
Time of trigger temperature.................... 1045 MDT
Time of overdevelopment........................ 1900 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 10308 ft MSL (5013 ft AGL)
Thermal soaring outlook for Tuesday 04/16...... Fair
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)................ Weak PVA
Potential height of wave....................... 31811 ft MSL (26516 ft AGL)
Wave soaring outlook for Tuesday 04/16......... Fair
Remarks... Strong and deep south/southwest flow on Monday, turning northwesterly
on Tuesday.
Sunrise/Sunset.................... 06:20:35 / 19:38:03 MDT
Total possible sunshine........... 13 hr 17 min 28 sec (797 min 28 sec)
Altitude of sun at 12:59:19 MDT... 60.38 degrees
Upper air data from numerical model forecast valid on 04/15/2024 at 0600 MDT
Freezing level.................. 13179 ft MSL (7884 ft AGL)
Convective condensation level... 19734 ft MSL (14439 ft AGL)
Lifted condensation level....... 18452 ft MSL (13157 ft AGL)
Lifted index.................... +1.6
K index......................... -2.3
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 -56.6 -69.9 240 47 24 -0.6 -0.3 M M M M M
45000 -57.5 -71.5 230 59 30 -0.9 -0.5 M M M M M
40000 -59.0 -74.2 225 72 37 -0.9 -0.5 M M M M M
38000 -57.0 -70.6 225 72 37 5.3 2.9 M M M M M
36000 -53.8 -64.8 225 70 36 5.3 2.9 M M M M M
34000 -50.3 -58.5 225 67 34 6.9 3.8 M M M M M
32000 -46.2 -51.2 220 61 31 6.9 3.8 M M M M M
30000 -41.8 -43.2 220 55 28 8.5 4.7 33.6 92.5 6.9 M M
29000 -39.2 -38.6 215 52 27 8.5 4.7 33.1 91.5 6.6 M M
28000 -36.0 -32.8 215 49 25 8.6 4.7 32.6 90.6 6.3 M M
27000 -33.5 -28.3 210 46 24 8.4 4.6 32.1 89.9 6.0 M M
26000 -31.0 -23.8 205 45 23 8.4 4.6 31.5 88.8 5.6 M M
25000 -28.4 -19.1 200 43 22 8.4 4.6 31.1 87.9 5.3 M M
24000 -25.9 -14.6 200 42 21 8.5 4.6 30.7 87.2 5.1 M M
23000 -23.4 -10.1 195 41 21 8.5 4.6 30.1 86.2 4.7 M M
22000 -20.9 -5.6 190 40 21 8.5 4.6 29.7 85.4 4.3 M M
21000 -18.4 -1.1 190 40 20 7.9 4.3 29.2 84.6 4.0 M M
20000 -16.0 3.2 190 39 20 7.9 4.4 28.5 83.3 3.4 M M
19500 -14.8 5.4 190 39 20 7.9 4.4 28.2 82.8 3.2 M M
19000 -13.6 7.5 190 39 20 7.9 4.4 27.9 82.3 3.0 M M
18500 -12.4 9.7 190 38 20 8.0 4.4 27.6 81.8 2.7 M M
18000 -11.3 11.7 190 38 19 8.0 4.4 27.3 81.2 2.5 M M
17500 -10.1 13.8 190 37 19 8.0 4.4 27.0 80.7 2.2 M M
17000 -8.9 16.0 190 36 19 7.8 4.3 26.7 80.1 1.9 M M
16500 -7.7 18.1 190 35 18 7.9 4.3 26.4 79.5 1.7 M M
16000 -6.6 20.1 190 34 18 7.4 4.0 26.0 78.9 1.3 M M
15500 -5.5 22.1 190 34 17 7.3 4.0 25.6 78.1 1.0 M M
15000 -4.4 24.1 190 33 17 7.4 4.1 25.2 77.4 0.6 M M
14500 -2.8 27.0 190 31 16 7.5 4.1 24.7 76.4 0.1 M M
14000 -1.7 28.9 190 30 15 7.7 4.3 24.3 75.8 -0.3 742 3.8
13500 -0.5 31.1 195 29 15 7.8 4.3 24.0 75.2 -0.6 693 3.5
13000 0.6 33.1 195 28 15 7.2 3.9 23.7 74.6 -0.9 644 3.3
12500 1.6 34.9 200 28 14 6.7 3.7 23.2 73.7 -1.4 601 3.1
12000 2.6 36.7 205 27 14 7.1 3.9 22.7 72.8 -1.9 557 2.8
11500 3.7 38.7 205 26 13 7.8 4.3 22.3 72.2 -2.3 509 2.6
11000 4.8 40.6 205 25 13 7.8 4.3 22.0 71.7 -2.6 460 2.3
10500 6.0 42.8 205 24 13 7.4 4.1 21.7 71.1 -2.9 410 2.1
10250 6.6 43.9 210 24 13 9.5 5.2 21.6 70.9 -3.1 385 2.0
10000 7.4 45.3 210 24 13 10.7 5.8 21.7 71.0 -3.0 354 1.8
9750 8.1 46.6 215 24 12 9.0 5.0 21.7 71.0 -3.0 326 1.7
9500 8.7 47.7 215 23 12 9.2 5.0 21.6 70.9 -3.1 298 1.5
9250 9.4 48.9 215 22 11 9.0 4.9 21.6 70.8 -3.2 271 1.4
9000 10.0 50.0 215 20 10 8.4 4.6 21.5 70.7 -3.3 245 1.2
8750 10.6 51.1 215 19 10 8.3 4.6 21.4 70.5 -3.4 219 1.1
8500 11.3 52.3 215 19 10 8.3 4.6 21.3 70.3 -3.5 192 1.0
8250 11.9 53.4 215 18 9 8.7 4.8 21.2 70.1 -3.6 166 0.8
8000 12.6 54.7 215 17 9 9.8 5.4 21.1 70.0 -3.6 138 0.7
7750 13.3 55.9 215 16 8 8.2 4.5 21.1 70.0 -3.7 109 0.6
7500 13.9 57.0 215 16 8 6.8 3.7 20.9 69.6 -3.9 85 0.4
7250 14.4 57.9 215 15 8 7.1 3.9 20.7 69.2 -4.1 62 0.3
7000 14.9 58.8 220 15 8 6.7 3.7 20.5 68.9 -4.3 39 0.2
6750 15.3 59.5 225 15 8 3.1 1.7 20.2 68.3 -4.6 20 0.1
6500 15.5 59.9 230 14 7 4.2 2.3 19.6 67.2 -5.2 7 0.0
6250 15.6 60.1 235 14 7 -6.2 -3.4 19.0 66.2 -5.8 M M
6000 14.5 58.1 230 12 6 -16.8 -9.2 17.2 62.9 -7.7 22 0.1
5750 13.1 55.6 225 11 6 -24.5 -13.4 15.1 59.2 -9.8 56 0.3
5500 10.2 50.4 215 8 4 -52.3 -28.7 11.5 52.7 -13.5 137 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/15/2024 at 0900 MDT | 04/15/2024 at 1200 MDT
|
CAPE... 0.0 LI... +4.5 | CAPE... 0.0 LI... +3.4
CINH... 0.0 K Index... -11.2 | CINH... 0.0 K Index... -7.2
|
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 -54.1 -65.4 240 43 22 -0.6 -0.3 | -52.9 -63.2 240 48 25 0.2 0.1
45000 -55.0 -67.0 225 62 32 -1.4 -0.8 | -52.6 -62.7 230 62 32 -0.4 -0.2
40000 -58.0 -72.4 220 77 40 -2.0 -1.1 | -54.4 -65.9 210 72 37 -1.2 -0.6
38000 -56.9 -70.4 215 80 41 4.3 2.4 | -54.0 -65.2 205 75 39 2.4 1.3
36000 -54.4 -65.9 215 80 41 4.3 2.4 | -52.5 -62.5 205 77 40 2.4 1.3
34000 -51.4 -60.5 215 79 41 7.3 4.0 | -50.7 -59.3 200 79 40 7.4 4.1
32000 -47.0 -52.6 210 74 38 7.3 4.0 | -46.6 -51.9 200 77 40 6.9 3.8
30000 -42.4 -44.3 205 68 35 8.7 4.8 | -42.5 -44.5 200 75 39 6.7 3.7
29000 -39.8 -39.6 205 64 33 8.7 4.8 | -40.0 -40.0 195 70 36 6.7 3.7
28000 -36.5 -33.7 200 60 31 8.7 4.8 | -38.0 -36.4 195 67 34 6.7 3.7
27000 -34.0 -29.2 195 57 29 8.1 4.4 | -36.0 -32.8 190 63 32 7.2 4.0
26000 -31.6 -24.9 190 53 27 8.0 4.4 | -33.6 -28.5 190 62 32 7.9 4.3
25000 -29.2 -20.6 185 50 26 8.0 4.4 | -31.3 -24.3 185 62 32 7.9 4.3
24000 -26.8 -16.2 180 47 24 7.9 4.3 | -28.9 -20.0 185 61 32 7.9 4.4
23000 -24.4 -11.9 180 47 24 7.8 4.3 | -26.5 -15.7 180 59 31 8.0 4.4
22000 -22.1 -7.8 180 47 24 7.8 4.3 | -24.1 -11.4 180 57 29 8.0 4.4
21000 -19.7 -3.5 180 47 24 7.7 4.2 | -21.7 -7.1 180 55 28 7.9 4.3
20000 -17.4 0.7 180 45 23 7.7 4.2 | -19.4 -2.9 180 52 27 7.8 4.3
19500 -16.3 2.7 180 45 23 7.7 4.2 | -18.3 -0.9 180 50 26 7.8 4.3
19000 -15.1 4.8 180 44 23 7.7 4.2 | -17.1 1.2 180 49 25 7.8 4.3
18500 -14.0 6.8 180 43 22 7.8 4.3 | -15.9 3.4 180 47 24 7.9 4.3
18000 -12.8 9.0 180 41 21 7.8 4.3 | -14.7 5.5 180 46 24 8.5 4.7
17500 -11.7 10.9 180 40 21 7.8 4.3 | -13.4 7.9 180 44 23 8.5 4.7
17000 -10.5 13.1 180 38 20 8.2 4.5 | -12.2 10.0 180 43 22 8.2 4.5
16500 -9.3 15.3 180 37 19 8.1 4.5 | -11.0 12.2 185 44 22 8.1 4.4
16000 -8.1 17.4 185 35 18 7.7 4.2 | -9.7 14.5 185 44 23 8.0 4.4
15500 -6.9 19.6 185 34 17 7.5 4.1 | -8.6 16.5 190 43 22 7.6 4.2
15000 -5.8 21.6 185 32 17 7.4 4.1 | -6.9 19.6 195 42 22 6.9 3.8
14500 -4.2 24.4 190 31 16 7.2 3.9 | -5.9 21.4 195 40 21 6.4 3.5
14000 -3.1 26.4 190 30 16 7.3 4.0 | -5.0 23.0 200 38 19 6.4 3.5
13500 -2.0 28.4 195 30 15 7.4 4.1 | -4.0 24.8 205 35 18 6.5 3.6
13000 -0.9 30.4 200 30 15 7.2 4.0 | -3.1 26.4 205 32 16 6.6 3.6
12500 0.1 32.2 205 29 15 6.9 3.8 | -2.0 28.4 205 29 15 8.2 4.5
12000 1.1 34.0 205 28 15 6.8 3.7 | -0.8 30.6 205 26 13 8.1 4.5
11500 2.1 35.8 210 27 14 6.6 3.6 | 0.5 32.9 205 23 12 8.9 4.9
11000 3.0 37.4 210 26 13 6.9 3.8 | 1.7 35.1 200 20 10 8.8 4.9
10500 4.1 39.4 210 24 12 7.6 4.2 | 3.0 37.4 200 18 9 8.4 4.6
10250 4.7 40.5 210 23 12 8.2 4.5 | 3.6 38.5 195 17 9 9.2 5.0
10000 5.3 41.5 210 22 11 9.5 5.2 | 4.4 39.9 195 16 8 10.0 5.5
9750 6.0 42.8 210 21 11 10.2 5.6 | 5.1 41.2 190 16 8 10.4 5.7
9500 6.8 44.2 205 20 10 10.5 5.7 | 5.9 42.6 190 15 8 11.0 6.0
9250 7.5 45.5 205 19 10 10.0 5.5 | 6.7 44.1 190 15 8 10.6 5.8
9000 8.2 46.8 205 19 10 8.2 4.5 | 7.4 45.3 190 15 8 7.9 4.3
8750 8.8 47.8 200 18 9 8.6 4.7 | 8.0 46.4 190 15 8 9.1 5.0
8500 9.5 49.1 200 17 9 10.0 5.5 | 8.8 47.8 190 15 8 11.3 6.2
8250 10.3 50.5 195 17 9 9.2 5.0 | 9.6 49.3 190 15 8 11.6 6.4
8000 11.0 51.8 195 16 8 11.1 6.1 | 10.4 50.7 190 14 7 7.9 4.3
7750 11.8 53.2 190 15 7 9.9 5.4 | 10.9 51.6 190 14 7 7.1 3.9
7500 12.4 54.3 190 14 7 7.4 4.1 | 11.6 52.9 190 14 7 10.8 5.9
7250 13.0 55.4 190 13 7 7.8 4.3 | 12.3 54.1 195 14 7 9.3 5.1
7000 13.4 56.1 190 12 6 3.8 2.1 | 13.1 55.6 195 14 7 11.7 6.4
6750 13.5 56.3 195 10 5 -0.1 -0.1 | 14.0 57.2 195 14 7 11.2 6.2
6500 13.5 56.3 200 9 4 0.0 0.0 | 14.7 58.5 195 14 7 8.6 4.7
6250 13.5 56.3 215 7 4 -1.5 -0.8 | 15.4 59.7 195 13 7 9.9 5.4
6000 13.2 55.8 220 6 3 -4.1 -2.2 | 16.2 61.2 195 13 7 11.6 6.4
5750 12.9 55.2 220 5 3 -3.3 -1.8 | 17.2 63.0 195 13 6 17.7 9.7
5500 12.7 54.9 220 4 2 3.8 2.1 | 18.8 65.8 195 12 6 25.1 13.8
04/15/2024 at 1500 MDT | 04/15/2024 at 1800 MDT
|
CAPE... +4.4 LI... +1.2 | CAPE... +18.9 LI... -0.9
CINH... -10.2 K Index... -4.8 | CINH... -136.7 K Index... +17.8
|
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 -53.2 -63.8 240 41 21 1.4 0.7 | -51.7 -61.1 235 40 21 1.1 0.6
45000 -51.2 -60.2 240 52 27 0.8 0.4 | -50.0 -58.0 245 40 21 1.0 0.6
40000 -50.9 -59.6 220 56 29 0.2 0.1 | -48.6 -55.5 230 41 21 1.0 0.5
38000 -50.5 -58.9 210 56 29 1.4 0.8 | -47.9 -54.2 220 41 21 1.4 0.8
36000 -49.6 -57.3 205 54 28 1.4 0.8 | -47.0 -52.6 210 39 20 1.4 0.8
34000 -48.6 -55.5 195 54 28 4.8 2.6 | -46.1 -51.0 200 37 19 2.5 1.4
32000 -45.3 -49.5 200 55 28 5.5 3.0 | -44.3 -47.7 195 32 17 3.0 1.6
30000 -42.0 -43.6 200 56 29 6.3 3.4 | -42.5 -44.5 185 27 14 3.9 2.1
29000 -39.5 -39.1 200 55 28 6.6 3.6 | -41.2 -42.2 185 25 13 4.5 2.5
28000 -37.6 -35.7 200 54 28 6.6 3.6 | -39.8 -39.6 180 24 12 4.5 2.5
27000 -35.6 -32.1 200 54 28 6.6 3.6 | -38.5 -37.3 175 22 11 4.6 2.5
26000 -34.0 -29.2 195 50 26 5.0 2.8 | -36.8 -34.2 170 20 11 6.2 3.4
25000 -32.5 -26.5 195 46 24 5.1 2.8 | -35.0 -31.0 165 19 10 6.2 3.4
24000 -31.0 -23.8 190 43 22 4.9 2.7 | -33.1 -27.6 155 18 9 6.3 3.4
23000 -29.0 -20.2 190 39 20 7.2 3.9 | -31.1 -24.0 145 18 9 7.3 4.0
22000 -26.9 -16.4 195 35 18 7.2 3.9 | -28.9 -20.0 135 19 10 7.3 4.0
21000 -24.8 -12.6 195 31 16 7.3 4.0 | -26.7 -16.1 130 20 10 7.3 4.0
20000 -22.3 -8.1 195 30 16 8.4 4.6 | -24.3 -11.7 130 20 10 8.7 4.8
19500 -21.1 -6.0 195 30 16 8.4 4.6 | -22.3 -8.1 135 19 10 8.7 4.8
19000 -19.8 -3.6 195 30 16 8.4 4.6 | -21.0 -5.8 135 18 10 8.7 4.8
18500 -18.5 -1.3 195 30 16 8.4 4.6 | -19.7 -3.5 140 18 9 8.8 4.8
18000 -17.3 0.9 195 29 15 8.7 4.8 | -18.4 -1.1 140 17 9 9.2 5.1
17500 -16.0 3.2 200 28 14 8.6 4.7 | -17.0 1.4 145 17 9 9.2 5.0
17000 -14.7 5.5 200 26 14 8.4 4.6 | -15.6 3.9 150 16 8 8.7 4.8
16500 -13.5 7.7 205 26 13 8.2 4.5 | -14.4 6.1 155 16 8 8.6 4.7
16000 -12.2 10.0 205 26 13 8.3 4.6 | -13.1 8.4 160 16 8 8.7 4.8
15500 -10.1 13.8 200 25 13 9.6 5.3 | -11.8 10.8 160 15 8 8.9 4.9
15000 -8.7 16.3 200 25 13 9.5 5.2 | -10.4 13.3 165 15 8 9.0 4.9
14500 -7.3 18.9 200 24 13 9.2 5.0 | -9.1 15.6 170 14 7 9.2 5.0
14000 -6.0 21.2 200 24 12 9.2 5.0 | -7.8 18.0 175 13 7 9.2 5.1
13500 -4.6 23.7 200 23 12 8.9 4.9 | -6.4 20.5 180 12 6 9.0 4.9
13000 -3.3 26.1 200 21 11 9.0 4.9 | -5.1 22.8 190 11 5 9.1 5.0
12500 -2.0 28.4 195 21 11 8.8 4.8 | -3.8 25.2 200 9 5 7.6 4.2
12000 -0.8 30.6 195 20 10 8.8 4.8 | -2.7 27.1 230 7 4 7.4 4.1
11500 0.6 33.1 195 20 10 9.9 5.5 | -1.7 28.9 260 8 4 6.3 3.4
11000 2.1 35.8 195 19 10 9.8 5.4 | -0.9 30.4 285 11 6 6.0 3.3
10500 3.6 38.5 195 19 10 11.6 6.4 | -0.1 31.8 300 16 8 5.7 3.1
10250 4.5 40.1 195 19 10 10.0 5.5 | 0.3 32.5 300 19 10 5.4 2.9
10000 5.1 41.2 195 19 10 7.8 4.3 | 0.6 33.1 305 22 11 4.6 2.5
9750 5.7 42.3 195 19 10 9.7 5.3 | 0.9 33.6 305 24 13 4.6 2.5
9500 6.5 43.7 195 19 10 11.7 6.4 | 1.3 34.3 305 27 14 5.5 3.0
9250 7.4 45.3 200 19 10 11.3 6.2 | 1.7 35.1 305 30 16 6.0 3.3
9000 8.1 46.6 200 19 10 6.6 3.6 | 2.2 36.0 305 33 17 5.0 2.8
8750 8.6 47.5 200 19 10 8.3 4.6 | 2.5 36.5 305 35 18 4.4 2.4
8500 9.4 48.9 200 19 10 12.4 6.8 | 2.9 37.2 300 37 19 5.0 2.7
8250 10.3 50.5 200 19 10 12.8 7.0 | 3.3 37.9 300 40 20 5.1 2.8
8000 11.2 52.2 200 19 10 7.9 4.3 | 3.7 38.7 295 42 22 4.7 2.6
7750 11.6 52.9 200 18 10 6.7 3.7 | 4.0 39.2 295 45 23 2.6 1.4
7500 12.4 54.3 200 18 9 11.2 6.1 | 4.1 39.4 290 43 22 2.0 1.1
7250 13.1 55.6 200 18 9 9.9 5.4 | 4.2 39.6 290 42 22 1.1 0.6
7000 13.9 57.0 200 18 9 10.5 5.8 | 4.3 39.7 285 41 21 5.7 3.1
6750 14.7 58.5 200 18 9 10.3 5.7 | 4.9 40.8 285 41 21 10.1 5.5
6500 15.4 59.7 200 18 9 10.0 5.5 | 5.6 42.1 280 39 20 8.8 4.8
6250 16.2 61.2 200 18 9 9.9 5.4 | 6.3 43.3 280 38 20 8.8 4.8
6000 16.9 62.4 200 17 9 10.6 5.8 | 7.0 44.6 280 37 19 11.0 6.0
5750 17.9 64.2 200 17 9 17.6 9.6 | 8.0 46.4 280 34 18 16.4 9.0
5500 19.5 67.1 200 15 8 26.7 14.6 | 9.3 48.7 280 29 15 19.1 10.5
________________________________________________________________________________
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
- National Weather Service
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- Page last modified: Sep 19th, 2023 19:10 UTC