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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 180104
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1803 MST Sunday, February 17, 2019
This forecast is for Monday, February 18, 2019:
If the trigger temperature of 22.0 F/-5.6 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 7719 ft MSL (2374 ft AGL)
Forecast maximum temperature................... 17.0 F/-8.8 C
Time of trigger temperature.................... None
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. None
Thermal soaring outlook for Tuesday 02/19...... Poor
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST)......... No change
Height of stable layer (12-18K ft MSL)......... 12240 ft MSL (6895 ft AGL)
Weak PVA/NVA (through 1700 MST)................ Weak NVA
Potential height of wave....................... 15688 ft MSL (10343 ft AGL)
Wave soaring outlook for Tuesday 02/19......... Poor
Remarks...
Sunrise/Sunset.................... 06:48:01 / 17:38:47 MST
Total possible sunshine........... 10 hr 50 min 45 sec (650 min 45 sec)
Altitude of sun at 12:13:24 MST... 38.61 degrees
Upper air data from numerical model forecast valid on 02/18/2019 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 9230 ft MSL (3885 ft AGL)
Lifted condensation level....... 8246 ft MSL (2901 ft AGL)
Lifted index.................... +10.5
K index......................... +5.7
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 -53.3 -63.9 250 24 12 1.2 0.7 M M M M M
45000 -51.5 -60.7 250 29 15 1.2 0.7 M M M M M
40000 -50.5 -58.9 245 30 15 0.4 0.2 M M M M M
38000 -50.3 -58.5 245 30 15 0.4 0.2 M M M M M
36000 -50.6 -59.1 245 30 15 -0.8 -0.4 M M M M M
34000 -51.1 -60.0 245 30 15 -0.8 -0.4 M M M M M
32000 -51.8 -61.2 245 27 14 -1.4 -0.8 M M M M M
30000 -52.6 -62.7 240 22 11 -1.4 -0.8 M M M M M
29000 -53.0 -63.4 240 20 10 -0.1 -0.1 21.7 71.0 22.4 M M
28000 -52.8 -63.0 235 17 9 0.9 0.5 17.9 64.3 19.9 M M
27000 -52.5 -62.5 230 15 8 0.9 0.5 14.4 58.0 17.5 M M
26000 -52.2 -62.0 225 13 7 0.2 0.1 11.1 52.0 15.1 M M
25000 -50.5 -58.9 225 11 6 7.8 4.3 9.6 49.2 14.1 M M
24000 -48.1 -54.6 220 10 5 7.7 4.3 8.8 47.8 13.6 M M
23000 -45.8 -50.4 220 9 5 7.7 4.2 8.1 46.6 13.3 M M
22000 -43.0 -45.4 220 9 4 9.7 5.3 7.9 46.2 13.3 M M
21000 -40.1 -40.2 220 8 4 9.7 5.3 7.9 46.2 13.4 M M
20000 -37.3 -35.1 220 8 4 9.5 5.2 7.9 46.2 13.6 M M
19500 -35.1 -31.2 225 8 4 9.5 5.2 7.8 46.0 13.6 M M
19000 -33.7 -28.7 225 8 4 9.5 5.2 7.7 45.9 13.6 M M
18500 -32.3 -26.1 225 8 4 9.5 5.2 7.7 45.8 13.7 M M
18000 -30.9 -23.6 225 9 4 9.2 5.0 7.7 45.8 13.8 M M
17500 -29.6 -21.3 225 9 5 8.6 4.7 7.5 45.5 13.7 M M
17000 -28.3 -18.9 225 9 5 8.6 4.7 7.3 45.1 13.6 M M
16500 -27.1 -16.8 220 10 5 7.7 4.2 7.0 44.6 13.4 M M
16000 -25.9 -14.6 220 10 5 7.8 4.3 6.7 44.0 13.2 M M
15500 -24.8 -12.6 215 11 6 7.0 3.9 6.3 43.3 12.9 M M
15000 -23.8 -10.8 215 11 6 7.0 3.8 5.8 42.5 12.5 M M
14500 -22.8 -9.0 210 12 6 6.3 3.5 5.3 41.6 12.2 M M
14000 -21.9 -7.4 210 12 6 6.0 3.3 4.7 40.4 11.6 M M
13500 -21.0 -5.8 205 12 6 4.7 2.6 4.1 39.3 11.1 M M
13000 -20.5 -4.9 205 12 6 3.7 2.0 3.0 37.5 10.3 M M
12500 -20.0 -4.0 205 12 6 1.8 1.0 2.0 35.7 9.4 M M
12000 -19.9 -3.8 200 12 6 0.5 0.3 0.5 32.9 8.0 M M
11500 -19.8 -3.6 200 11 6 1.2 0.6 -1.0 30.2 6.7 M M
11000 -19.6 -3.3 195 11 6 1.4 0.8 -2.3 27.9 5.5 M M
10500 -19.2 -2.6 190 10 5 4.4 2.4 -3.5 25.8 4.4 M M
10250 -18.8 -1.8 185 10 5 5.2 2.9 -3.8 25.1 4.1 M M
10000 -18.5 -1.3 185 10 5 5.3 2.9 -4.2 24.4 3.7 M M
9750 -18.1 -0.6 180 9 5 4.3 2.4 -4.6 23.8 3.4 M M
9500 -17.8 -0.0 180 9 5 3.8 2.1 -5.0 22.9 2.9 M M
9250 -17.5 0.5 180 8 4 4.4 2.4 -5.5 22.1 2.5 M M
9000 -17.2 1.0 175 8 4 4.0 2.2 -5.9 21.4 2.1 M M
8750 -16.9 1.6 175 8 4 4.0 2.2 -6.4 20.6 1.7 M M
8500 -16.6 2.1 170 7 4 4.8 2.6 -6.8 19.8 1.3 M M
8250 -16.2 2.8 160 7 4 5.5 3.0 -7.1 19.2 1.0 M M
8000 -15.8 3.6 155 7 4 4.5 2.5 -7.5 18.5 0.6 M M
7750 -15.5 4.1 145 7 4 3.7 2.0 -7.9 17.7 0.2 M M
7500 -15.2 4.6 135 7 4 3.4 1.9 -8.4 16.9 -0.3 157 0.8
7250 -15.0 5.0 125 7 4 4.6 2.5 -8.9 16.0 -0.8 141 0.7
7000 -14.5 5.9 120 7 4 6.9 3.8 -9.2 15.5 -1.1 121 0.6
6750 -14.0 6.8 110 7 4 7.0 3.8 -9.4 15.1 -1.3 97 0.5
6500 -13.5 7.7 105 7 3 7.5 4.1 -9.6 14.8 -1.5 74 0.4
6250 -12.9 8.8 100 6 3 9.5 5.2 -9.7 14.6 -1.6 48 0.2
6000 -12.1 10.2 095 6 3 10.3 5.7 -9.6 14.6 -1.6 18 0.1
5750 -11.3 11.7 095 6 3 10.1 5.6 -9.6 14.7 -1.5 M M
5500 -10.5 13.1 090 5 3 12.2 6.7 -9.5 14.8 -1.5 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
02/18/2019 at 0800 MST | 02/18/2019 at 1100 MST
|
CAPE... +0.4 LI... +7.4 | CAPE... +5.7 LI... +5.3
CINH... 0.0 K Index... +2.3 | CINH... 0.0 K Index... +2.4
|
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 -53.9 -65.0 250 24 12 1.1 0.6 | -53.9 -65.0 245 26 13 1.0 0.6
45000 -52.2 -62.0 250 30 15 1.1 0.6 | -52.3 -62.1 245 30 16 1.0 0.6
40000 -51.1 -60.0 245 31 16 0.7 0.4 | -51.4 -60.5 240 34 17 0.5 0.3
38000 -50.7 -59.3 240 32 16 0.7 0.4 | -51.1 -60.0 240 35 18 0.4 0.2
36000 -50.7 -59.3 240 32 17 -0.2 -0.1 | -51.1 -60.0 240 36 18 0.0 0.0
34000 -50.8 -59.4 240 32 17 -0.2 -0.1 | -51.0 -59.8 235 37 19 0.0 0.0
32000 -50.6 -59.1 240 31 16 0.6 0.3 | -50.7 -59.3 235 37 19 1.1 0.6
30000 -50.3 -58.5 240 28 14 0.6 0.3 | -50.0 -58.0 240 35 18 1.1 0.6
29000 -50.1 -58.2 240 26 13 0.0 0.0 | -49.7 -57.5 240 34 17 0.9 0.5
28000 -50.3 -58.5 240 22 11 -0.3 -0.2 | -49.5 -57.1 240 30 15 0.8 0.4
27000 -50.4 -58.7 240 19 10 -0.4 -0.2 | -49.2 -56.6 240 26 13 0.8 0.4
26000 -50.5 -58.9 240 15 8 -0.9 -0.5 | -49.0 -56.2 240 22 11 0.5 0.3
25000 -49.3 -56.7 235 13 6 5.5 3.0 | -48.1 -54.6 235 18 9 3.9 2.1
24000 -47.7 -53.9 235 11 5 5.5 3.0 | -46.9 -52.4 235 15 8 3.8 2.1
23000 -46.0 -50.8 230 9 4 5.3 2.9 | -45.8 -50.4 230 11 6 3.6 2.0
22000 -43.5 -46.3 230 8 4 9.1 5.0 | -43.5 -46.3 225 10 5 8.7 4.8
21000 -40.8 -41.4 230 8 4 9.0 5.0 | -40.3 -40.5 225 9 5 8.6 4.7
20000 -38.1 -36.6 230 7 4 9.4 5.1 | -37.6 -35.7 230 9 4 9.4 5.2
19500 -36.0 -32.8 230 7 4 9.5 5.2 | -36.2 -33.2 230 9 4 9.4 5.2
19000 -34.6 -30.3 230 7 4 9.5 5.2 | -34.8 -30.6 230 9 5 9.4 5.2
18500 -33.1 -27.6 230 8 4 9.5 5.2 | -33.4 -28.1 230 9 5 9.4 5.2
18000 -31.7 -25.1 230 8 4 9.3 5.1 | -32.0 -25.6 230 9 5 9.3 5.1
17500 -30.4 -22.7 230 8 4 9.1 5.0 | -30.6 -23.1 230 9 5 9.1 5.0
17000 -29.0 -20.2 230 8 4 9.1 5.0 | -29.2 -20.6 235 9 5 9.1 5.0
16500 -27.7 -17.9 225 8 4 8.4 4.6 | -27.9 -18.2 235 10 5 8.6 4.7
16000 -26.4 -15.5 225 9 4 8.5 4.7 | -26.6 -15.9 235 10 5 8.7 4.8
15500 -25.2 -13.4 225 9 5 7.5 4.1 | -25.3 -13.5 235 10 5 8.1 4.5
15000 -24.1 -11.4 225 9 5 7.4 4.1 | -24.1 -11.4 230 11 5 8.1 4.5
14500 -23.1 -9.6 225 10 5 6.1 3.3 | -22.9 -9.2 230 11 6 7.4 4.1
14000 -22.3 -8.1 225 10 5 5.6 3.1 | -21.9 -7.4 230 11 6 7.2 4.0
13500 -21.5 -6.7 220 11 6 4.0 2.2 | -20.8 -5.4 230 12 6 5.8 3.2
13000 -21.0 -5.8 220 11 6 3.0 1.6 | -20.1 -4.2 230 12 6 5.1 2.8
12500 -20.6 -5.1 215 11 6 1.3 0.7 | -19.4 -2.9 230 12 6 3.5 1.9
12000 -20.6 -5.1 215 11 6 0.3 0.1 | -19.0 -2.2 225 12 6 2.7 1.5
11500 -20.6 -5.1 210 10 5 1.0 0.6 | -18.6 -1.5 225 11 6 1.8 1.0
11000 -20.4 -4.7 210 10 5 1.1 0.6 | -18.4 -1.1 220 11 5 1.5 0.8
10500 -20.0 -4.0 200 10 5 4.5 2.4 | -18.2 -0.8 220 9 5 1.3 0.7
10250 -19.6 -3.3 200 10 5 4.9 2.7 | -18.1 -0.6 215 9 5 1.4 0.7
10000 -19.3 -2.7 195 10 5 5.3 2.9 | -18.0 -0.4 210 8 4 1.1 0.6
9750 -18.9 -2.0 190 10 5 3.5 1.9 | -17.9 -0.2 205 8 4 2.1 1.2
9500 -18.7 -1.7 190 9 5 4.3 2.4 | -17.7 0.1 200 8 4 4.1 2.2
9250 -18.2 -0.8 185 9 5 6.9 3.8 | -17.4 0.7 190 7 4 4.7 2.6
9000 -17.8 -0.0 185 9 5 5.5 3.0 | -17.0 1.4 180 7 3 3.9 2.2
8750 -17.4 0.7 180 9 5 4.4 2.4 | -16.8 1.8 175 6 3 4.6 2.5
8500 -17.1 1.2 175 9 5 5.2 2.8 | -16.3 2.7 170 6 3 6.9 3.8
8250 -16.6 2.1 170 9 5 6.0 3.3 | -15.8 3.6 165 6 3 7.5 4.1
8000 -16.2 2.8 165 9 5 5.1 2.8 | -15.2 4.6 160 6 3 7.1 3.9
7750 -15.9 3.4 160 9 5 4.5 2.5 | -14.7 5.5 155 6 3 7.2 3.9
7500 -15.5 4.1 155 9 4 4.7 2.6 | -14.2 6.4 155 5 3 7.4 4.0
7250 -15.2 4.6 145 8 4 4.9 2.7 | -13.6 7.5 150 5 3 8.0 4.4
7000 -14.8 5.4 140 8 4 5.2 2.8 | -13.0 8.6 145 5 3 8.9 4.9
6750 -14.4 6.1 135 8 4 5.0 2.7 | -12.3 9.9 145 5 3 8.7 4.8
6500 -14.0 6.8 130 7 4 5.6 3.1 | -11.6 11.1 140 5 3 9.3 5.1
6250 -13.6 7.5 120 7 3 7.0 3.8 | -10.9 12.4 140 5 2 10.8 5.9
6000 -13.0 8.6 120 6 3 7.2 3.9 | -10.0 14.0 135 5 2 11.2 6.2
5750 -12.5 9.5 115 6 3 7.5 4.1 | -9.2 15.4 135 4 2 11.1 6.1
5500 -11.9 10.6 105 5 2 9.9 5.4 | -8.3 17.1 130 4 2 15.6 8.6
02/18/2019 at 1400 MST | 02/18/2019 at 1700 MST
|
CAPE... +5.4 LI... +3.7 | CAPE... +4.2 LI... +3.3
CINH... -0.0 K Index... +3.8 | CINH... -0.0 K Index... +5.0
|
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 -54.1 -65.4 245 27 14 1.2 0.6 | -54.1 -65.4 250 27 14 0.9 0.5
45000 -52.3 -62.1 245 32 16 1.2 0.6 | -52.8 -63.0 245 32 17 0.9 0.5
40000 -51.7 -61.1 240 36 18 0.2 0.1 | -52.2 -62.0 240 35 18 0.3 0.1
38000 -51.6 -60.9 240 38 19 0.2 0.1 | -52.0 -61.6 240 36 19 0.3 0.2
36000 -51.5 -60.7 235 39 20 0.1 0.1 | -51.7 -61.1 235 38 20 0.4 0.2
34000 -51.4 -60.5 235 40 21 0.1 0.1 | -51.5 -60.7 235 40 20 0.4 0.2
32000 -51.0 -59.8 235 41 21 1.1 0.6 | -50.8 -59.4 235 40 21 1.6 0.9
30000 -50.4 -58.7 235 40 20 1.1 0.6 | -49.9 -57.8 235 40 20 1.6 0.9
29000 -50.0 -58.0 235 39 20 2.0 1.1 | -49.4 -56.9 235 39 20 1.6 0.9
28000 -49.3 -56.7 240 36 19 2.2 1.2 | -48.9 -56.0 235 36 19 1.5 0.8
27000 -48.7 -55.7 240 33 17 2.2 1.2 | -48.5 -55.3 235 34 17 1.5 0.8
26000 -48.0 -54.4 240 30 15 2.0 1.1 | -48.0 -54.4 240 31 16 1.3 0.7
25000 -46.9 -52.4 240 26 13 4.0 2.2 | -47.0 -52.6 240 27 14 4.1 2.3
24000 -45.7 -50.3 240 21 11 4.0 2.2 | -45.7 -50.3 240 22 12 4.1 2.3
23000 -44.5 -48.1 235 17 9 4.0 2.2 | -44.5 -48.1 240 18 9 4.4 2.4
22000 -42.4 -44.3 235 14 7 8.1 4.4 | -42.1 -43.8 235 16 8 8.7 4.8
21000 -39.3 -38.7 240 12 6 8.1 4.4 | -38.8 -37.8 230 15 8 8.7 4.8
20000 -36.8 -34.2 235 11 5 8.7 4.8 | -36.2 -33.2 230 14 7 8.9 4.9
19500 -35.5 -31.9 235 10 5 8.7 4.8 | -34.9 -30.8 225 14 7 8.9 4.9
19000 -34.2 -29.6 235 10 5 8.7 4.8 | -33.5 -28.3 225 13 7 8.9 4.9
18500 -33.0 -27.4 230 10 5 8.7 4.8 | -32.2 -26.0 225 12 6 8.9 4.9
18000 -31.7 -25.1 230 9 5 8.7 4.8 | -30.9 -23.6 220 11 6 8.8 4.8
17500 -30.3 -22.5 230 9 5 8.8 4.8 | -29.6 -21.3 220 11 5 8.6 4.7
17000 -29.0 -20.2 230 9 5 8.8 4.8 | -28.3 -18.9 220 10 5 8.6 4.7
16500 -27.7 -17.9 230 9 5 8.9 4.9 | -27.0 -16.6 220 9 5 8.3 4.6
16000 -26.4 -15.5 230 10 5 8.9 4.9 | -25.8 -14.4 215 9 5 8.3 4.6
15500 -25.0 -13.0 230 10 5 9.0 5.0 | -24.5 -12.1 215 8 4 8.4 4.6
15000 -23.7 -10.7 230 10 5 9.1 5.0 | -23.3 -9.9 215 8 4 8.4 4.6
14500 -22.3 -8.1 230 10 5 8.6 4.7 | -22.0 -7.6 215 8 4 8.3 4.6
14000 -21.1 -6.0 230 10 5 8.4 4.6 | -20.8 -5.4 215 8 4 8.3 4.6
13500 -19.8 -3.6 230 11 6 7.5 4.1 | -19.5 -3.1 215 8 4 7.5 4.1
13000 -18.8 -1.8 230 11 6 6.9 3.8 | -18.5 -1.3 220 8 4 7.1 3.9
12500 -17.8 -0.0 230 11 6 5.3 2.9 | -17.5 0.5 220 8 4 6.0 3.3
12000 -17.2 1.0 230 11 6 4.2 2.3 | -16.7 1.9 220 8 4 5.3 2.9
11500 -16.7 1.9 225 10 5 1.6 0.9 | -16.0 3.2 220 8 4 2.7 1.5
11000 -16.7 1.9 225 9 5 0.4 0.2 | -15.8 3.6 215 7 4 1.6 0.9
10500 -16.7 1.9 215 7 4 -0.5 -0.3 | -15.7 3.7 210 6 3 -0.8 -0.4
10250 -16.7 1.9 210 6 3 -0.5 -0.3 | -15.8 3.6 205 4 2 -1.2 -0.7
10000 -16.8 1.8 200 5 3 -1.4 -0.8 | -15.9 3.4 195 4 2 -2.0 -1.1
9750 -16.8 1.8 185 4 2 2.5 1.4 | -16.0 3.2 175 3 1 2.4 1.3
9500 -16.4 2.5 170 4 2 6.8 3.8 | -15.6 3.9 165 3 1 6.8 3.7
9250 -15.9 3.4 160 4 2 6.4 3.5 | -15.1 4.8 155 3 2 6.0 3.3
9000 -15.5 4.1 155 4 2 5.8 3.2 | -14.7 5.5 150 3 2 5.9 3.2
8750 -15.0 5.0 150 4 2 6.7 3.7 | -14.2 6.4 145 3 2 6.7 3.7
8500 -14.4 6.1 145 4 2 9.0 4.9 | -13.7 7.3 145 4 2 8.2 4.5
8250 -13.7 7.3 140 5 2 8.9 4.9 | -13.1 8.4 145 4 2 7.6 4.2
8000 -13.1 8.4 135 5 2 9.8 5.4 | -12.5 9.5 145 4 2 9.4 5.2
7750 -12.3 9.9 135 4 2 10.1 5.5 | -11.7 10.9 140 4 2 10.3 5.6
7500 -11.6 11.1 135 4 2 8.8 4.8 | -11.0 12.2 140 4 2 8.5 4.7
7250 -10.9 12.4 130 4 2 9.3 5.1 | -10.3 13.5 140 4 2 8.9 4.9
7000 -10.2 13.6 130 4 2 11.5 6.3 | -9.6 14.7 135 4 2 10.6 5.8
6750 -9.3 15.3 130 4 2 10.3 5.7 | -8.8 16.2 135 4 2 9.8 5.4
6500 -8.6 16.5 130 4 2 8.0 4.4 | -8.2 17.2 135 4 2 8.1 4.4
6250 -8.0 17.6 125 4 2 10.0 5.5 | -7.5 18.5 130 4 2 9.6 5.3
6000 -7.1 19.2 125 4 2 11.8 6.5 | -6.7 19.9 130 4 2 11.2 6.1
5750 -6.3 20.7 125 4 2 9.8 5.4 | -5.9 21.4 130 4 2 9.3 5.1
5500 -5.6 21.9 125 3 2 12.1 6.6 | -5.3 22.5 125 3 2 8.7 4.8
________________________________________________________________________________
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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- Page last modified: Feb 6th, 2019 17:08 UTC