Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 130121
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1921 MDT Wednesday, June 12, 2013
This forecast is for Thursday, June 13, 2013:
If the trigger temperature of 82.7 F/28.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1118 ft/min (5.7 m/s)
Maximum height of thermals.................. 18658 ft MSL (13371 ft AGL)
Forecast maximum temperature................... 94.0 F/34.9 C
Time of trigger temperature.................... 1015 MDT
Time of overdevelopment........................ 1500 MDT
Middle/high clouds during soaring window....... Overcast thin high
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10829 ft MSL (5542 ft AGL)
Thermal soaring outlook for Friday 06/14....... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 22260 ft MSL (16973 ft AGL)
Wave soaring outlook for Friday 06/14.......... Poor
Remarks...
Sunrise/Sunset.................... 05:31:00 / 20:28:07 MDT
Total possible sunshine........... 14 hr 57 min 7 sec (897 min 7 sec)
Altitude of sun at 12:59:43 MDT... 73.45 degrees
Upper air data from numerical model forecast valid on 06/13/2013 at 0600 MDT
Freezing level.................. 16370 ft MSL (11083 ft AGL)
Convective condensation level... 16765 ft MSL (11478 ft AGL)
Lifted condensation level....... 17333 ft MSL (12046 ft AGL)
Lifted index.................... -4.2
K index......................... +11.1
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 -63.5 -82.3 250 30 16 2.0 1.1 M M M M M
45000 -60.5 -76.9 245 34 18 1.8 1.0 M M M M M
40000 -56.9 -70.4 230 49 25 7.8 4.3 M M M M M
38000 -52.1 -61.8 230 47 24 8.0 4.4 M M M M M
36000 -47.3 -53.1 225 45 23 7.9 4.4 M M M M M
34000 -42.2 -44.0 230 43 22 8.5 4.6 M M M M M
32000 -37.2 -35.0 235 41 21 8.3 4.6 M M M M M
30000 -31.6 -24.9 240 38 19 8.1 4.4 43.6 110.4 6.9 M M
29000 -29.2 -20.6 240 36 19 8.1 4.4 43.0 109.4 6.6 M M
28000 -26.8 -16.2 240 34 18 7.8 4.3 42.4 108.4 6.2 M M
27000 -24.5 -12.1 245 34 17 7.8 4.3 41.6 106.9 5.6 M M
26000 -22.1 -7.8 250 33 17 7.8 4.3 40.9 105.6 5.1 M M
25000 -19.8 -3.6 255 33 17 7.2 4.0 40.3 104.5 4.7 M M
24000 -17.9 -0.2 255 36 18 6.2 3.4 38.9 102.0 3.6 M M
23000 -16.1 3.0 255 39 20 6.2 3.4 37.6 99.7 2.5 M M
22000 -14.3 6.3 255 42 21 7.4 4.1 36.4 97.6 1.5 M M
21000 -11.8 10.8 255 40 21 8.5 4.6 35.9 96.6 1.0 M M
20000 -9.3 15.3 255 39 20 8.5 4.6 35.5 95.8 0.6 M M
19500 -8.0 17.6 255 38 20 8.5 4.7 35.3 95.5 0.5 M M
19000 -6.8 19.8 255 37 19 8.0 4.4 35.0 95.0 0.2 M M
18500 -5.6 21.9 250 34 18 8.0 4.4 34.7 94.5 -0.0 1209 6.1
18000 -4.4 24.1 245 32 16 8.1 4.5 34.4 94.0 -0.3 1158 5.9
17500 -3.2 26.2 245 30 15 8.2 4.5 34.2 93.5 -0.6 1107 5.6
17000 -2.0 28.4 240 27 14 8.2 4.5 33.9 93.0 -0.8 1056 5.4
16500 -0.7 30.7 240 26 13 9.6 5.3 33.8 92.8 -1.0 1001 5.1
16000 0.7 33.3 240 25 13 9.5 5.2 33.7 92.7 -1.0 944 4.8
15500 2.2 36.0 240 25 13 9.3 5.1 33.7 92.6 -1.1 887 4.5
15000 4.2 39.6 245 23 12 9.2 5.0 33.5 92.4 -1.2 803 4.1
14500 5.6 42.1 245 23 12 9.5 5.2 33.5 92.3 -1.3 747 3.8
14000 7.0 44.6 245 22 12 9.5 5.2 33.4 92.2 -1.3 689 3.5
13500 8.4 47.1 250 22 11 9.3 5.1 33.4 92.1 -1.4 632 3.2
13000 9.8 49.6 250 21 11 9.1 5.0 33.3 91.9 -1.5 576 2.9
12500 11.2 52.2 250 20 10 8.5 4.7 33.2 91.8 -1.6 521 2.6
12000 12.3 54.1 250 19 10 7.9 4.3 32.9 91.2 -1.9 471 2.4
11500 13.5 56.3 250 18 9 7.0 3.9 32.6 90.7 -2.2 421 2.1
11000 14.3 57.7 250 16 8 5.5 3.0 32.0 89.6 -2.8 382 1.9
10500 15.1 59.2 250 14 7 3.0 1.7 31.4 88.4 -3.5 343 1.7
10250 15.2 59.4 250 14 7 1.9 1.0 30.7 87.2 -4.2 333 1.7
10000 15.5 59.9 250 13 7 4.8 2.6 30.2 86.4 -4.7 318 1.6
9750 15.7 60.3 250 12 6 4.9 2.7 29.8 85.7 -5.1 303 1.5
9500 16.0 60.8 250 10 5 3.6 2.0 29.4 85.0 -5.6 287 1.5
9250 16.1 61.0 250 10 5 1.6 0.9 28.8 83.9 -6.2 276 1.4
9000 16.2 61.2 255 9 5 1.4 0.8 28.2 82.8 -6.9 266 1.4
8750 16.3 61.3 260 9 5 1.9 1.0 27.6 81.6 -7.6 257 1.3
8500 16.3 61.3 265 9 4 0.0 0.0 26.9 80.5 -8.3 248 1.3
8250 16.2 61.2 260 8 4 -2.0 -1.1 26.1 78.9 -9.2 245 1.2
8000 16.0 60.8 260 8 4 -1.6 -0.9 25.2 77.3 -10.1 243 1.2
7750 15.8 60.4 260 7 4 -1.7 -0.9 24.3 75.7 -11.0 240 1.2
7500 15.6 60.1 255 7 4 -2.7 -1.5 23.4 74.1 -12.0 239 1.2
7250 15.3 59.5 260 6 3 -3.3 -1.8 22.4 72.3 -13.0 241 1.2
7000 15.0 59.0 265 6 3 -3.6 -2.0 21.4 70.5 -14.1 242 1.2
6750 14.7 58.5 270 5 3 -3.6 -2.0 20.4 68.7 -15.2 245 1.2
6500 14.5 58.1 285 5 2 -2.1 -1.1 19.4 66.9 -16.2 245 1.2
6250 14.3 57.7 300 4 2 -1.4 -0.8 18.5 65.4 -17.2 243 1.2
6000 14.1 57.4 320 4 2 -1.7 -0.9 17.7 63.8 -18.1 241 1.2
5750 13.9 57.0 320 4 2 -2.2 -1.2 16.8 62.3 -19.1 239 1.2
5500 13.7 56.7 305 4 2 -2.7 -1.5 15.9 60.7 -20.0 238 1.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/13/2013 at 0900 MDT | 06/13/2013 at 1200 MDT
|
K index... +10.8 LI... +1.0 | K index... +14.1 LI... -1.0
CAPE... 0.0 CIN... -1.8 | CAPE... +367.2 CIN... -366.8
|
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 -63.0 -81.4 240 25 13 2.7 1.5 | -62.6 -80.7 235 26 13 2.6 1.5
45000 -59.6 -75.3 240 31 16 0.9 0.5 | -59.0 -74.2 235 37 19 1.3 0.7
40000 -57.1 -70.8 235 45 23 7.8 4.3 | -56.2 -69.2 230 47 24 6.9 3.8
38000 -52.3 -62.1 235 41 21 8.0 4.4 | -51.9 -61.4 235 44 23 7.0 3.9
36000 -47.6 -53.7 230 37 19 7.9 4.4 | -47.7 -53.9 235 41 21 6.9 3.8
34000 -42.5 -44.5 230 35 18 8.5 4.7 | -42.8 -45.0 235 39 20 8.3 4.6
32000 -37.4 -35.3 230 33 17 8.4 4.6 | -37.8 -36.0 230 38 20 8.2 4.5
30000 -32.2 -26.0 235 32 17 7.5 4.1 | -32.6 -26.7 230 37 19 7.7 4.2
29000 -30.0 -22.0 235 32 16 7.5 4.1 | -30.3 -22.5 230 37 19 7.8 4.3
28000 -27.7 -17.9 240 32 16 8.4 4.6 | -27.9 -18.2 225 37 19 7.9 4.3
27000 -25.1 -13.2 240 31 16 8.4 4.6 | -25.6 -14.1 230 36 18 7.9 4.3
26000 -22.6 -8.7 245 30 15 8.4 4.6 | -23.2 -9.8 230 34 18 7.9 4.3
25000 -20.1 -4.2 245 29 15 7.5 4.1 | -20.9 -5.6 230 33 17 7.4 4.0
24000 -18.3 -0.9 245 32 17 6.2 3.4 | -18.9 -2.0 230 34 18 6.6 3.6
23000 -16.5 2.3 240 35 18 6.3 3.5 | -17.0 1.4 230 35 18 6.6 3.6
22000 -14.7 5.5 240 38 20 7.5 4.1 | -15.0 5.0 235 36 19 7.9 4.3
21000 -12.2 10.0 240 37 19 8.4 4.6 | -12.4 9.7 235 36 18 8.9 4.9
20000 -9.7 14.5 240 35 18 8.4 4.6 | -9.8 14.4 235 35 18 9.0 4.9
19500 -8.5 16.7 240 35 18 8.4 4.6 | -8.5 16.7 235 34 18 9.0 4.9
19000 -7.3 18.9 245 34 18 8.4 4.6 | -7.2 19.0 235 33 17 8.5 4.6
18500 -6.0 21.2 245 34 17 8.4 4.6 | -6.0 21.2 235 32 17 8.5 4.7
18000 -4.7 23.5 245 34 17 8.8 4.9 | -4.7 23.5 235 31 16 9.0 5.0
17500 -3.4 25.9 245 33 17 9.1 5.0 | -3.3 26.1 235 31 16 9.3 5.1
17000 -2.0 28.4 245 32 16 9.1 5.0 | -1.9 28.6 235 30 16 9.3 5.1
16500 -0.6 30.9 245 31 16 9.5 5.2 | -0.5 31.1 235 30 15 9.0 5.0
16000 0.8 33.4 245 30 16 9.5 5.2 | 0.8 33.4 235 29 15 9.1 5.0
15500 2.2 36.0 245 30 15 9.1 5.0 | 2.2 36.0 235 28 14 8.9 4.9
15000 4.2 39.6 245 29 15 9.0 5.0 | 4.2 39.6 235 27 14 8.9 4.9
14500 5.6 42.1 245 28 14 9.2 5.1 | 5.6 42.1 235 26 13 9.6 5.3
14000 7.0 44.6 245 26 14 9.2 5.0 | 7.0 44.6 235 25 13 9.5 5.2
13500 8.3 46.9 245 25 13 9.2 5.0 | 8.5 47.3 235 25 13 9.7 5.3
13000 9.7 49.5 245 23 12 9.2 5.0 | 9.9 49.8 235 24 12 9.7 5.3
12500 11.1 52.0 245 21 11 9.3 5.1 | 11.3 52.3 235 24 12 9.4 5.2
12000 12.5 54.5 245 20 10 9.3 5.1 | 12.7 54.9 235 23 12 9.2 5.1
11500 13.9 57.0 245 19 10 9.2 5.1 | 14.1 57.4 235 22 11 8.9 4.9
11000 15.3 59.5 245 18 9 8.8 4.8 | 15.4 59.7 235 21 11 8.4 4.6
10500 16.6 61.9 240 17 9 3.9 2.1 | 16.7 62.1 230 19 10 4.4 2.4
10250 16.7 62.1 240 17 9 4.3 2.4 | 16.9 62.4 230 19 10 5.4 3.0
10000 17.4 63.3 240 16 8 10.9 6.0 | 17.6 63.7 230 18 9 11.2 6.1
9750 18.2 64.8 240 16 8 10.2 5.6 | 18.4 65.1 230 17 9 10.5 5.7
9500 18.9 66.0 240 15 8 6.6 3.6 | 19.1 66.4 225 16 8 7.6 4.2
9250 19.1 66.4 235 14 7 1.4 0.7 | 19.5 67.1 225 15 8 3.7 2.0
9000 19.2 66.6 235 14 7 1.1 0.6 | 19.8 67.6 220 14 7 4.1 2.2
8750 19.2 66.6 235 12 6 1.3 0.7 | 20.1 68.2 220 13 7 5.2 2.8
8500 19.2 66.6 235 11 6 -0.8 -0.4 | 20.4 68.7 215 12 6 1.1 0.6
8250 19.0 66.2 235 10 5 -3.0 -1.7 | 20.2 68.4 210 10 5 -3.0 -1.7
8000 18.7 65.7 235 8 4 -2.6 -1.4 | 20.0 68.0 200 9 5 -2.1 -1.2
7750 18.5 65.3 240 7 4 -2.8 -1.5 | 19.7 67.5 190 9 4 -2.6 -1.4
7500 18.1 64.6 245 6 3 -4.7 -2.6 | 19.5 67.1 180 8 4 -1.1 -0.6
7250 17.7 63.9 250 6 3 -5.7 -3.1 | 19.3 66.7 170 7 3 0.2 0.1
7000 17.2 63.0 255 5 3 -6.6 -3.6 | 19.1 66.4 155 5 3 -0.4 -0.2
6750 16.6 61.9 265 4 2 -5.5 -3.0 | 19.0 66.2 135 4 2 3.2 1.7
6500 16.3 61.3 270 4 2 -0.2 -0.1 | 19.4 66.9 120 4 2 9.4 5.1
6250 16.3 61.3 275 3 1 1.8 1.0 | 20.1 68.2 120 4 2 10.9 6.0
6000 16.3 61.3 285 2 1 0.7 0.4 | 20.9 69.6 120 3 2 9.9 5.4
5750 16.4 61.5 305 1 0 8.4 4.6 | 21.7 71.1 115 3 2 14.5 8.0
5500 17.6 63.7 355 1 0 22.6 12.4 | 23.1 73.6 105 3 2 23.4 12.9
06/13/2013 at 1500 MDT | 06/13/2013 at 1800 MDT
|
K index... +27.2 LI... -4.6 | K index... +23.4 LI... -3.5
CAPE... M CIN... -41.4 | CAPE... +1216.3 CIN... -51.2
|
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 -62.8 -81.0 230 29 15 2.3 1.3 | -63.4 -82.1 230 34 18 2.8 1.5
45000 -59.5 -75.1 235 43 22 1.5 0.8 | -59.7 -75.5 235 42 21 1.5 0.8
40000 -56.3 -69.3 230 48 25 7.1 3.9 | -56.5 -69.7 230 45 23 7.3 4.0
38000 -52.0 -61.6 230 47 24 7.2 3.9 | -51.9 -61.4 230 43 22 7.5 4.1
36000 -47.7 -53.9 235 45 23 7.1 3.9 | -47.4 -53.3 225 41 21 7.5 4.1
34000 -42.9 -45.2 230 45 23 8.1 4.4 | -42.6 -44.7 225 41 21 8.2 4.5
32000 -38.1 -36.6 230 45 23 8.0 4.4 | -37.6 -35.7 225 41 21 8.1 4.4
30000 -32.6 -26.7 230 44 23 8.1 4.4 | -33.0 -27.4 230 42 22 7.7 4.2
29000 -30.2 -22.4 235 44 22 8.1 4.4 | -30.1 -22.2 230 43 22 7.7 4.2
28000 -27.8 -18.0 235 43 22 7.7 4.2 | -27.8 -18.0 230 43 22 7.8 4.3
27000 -25.5 -13.9 235 43 22 7.8 4.3 | -25.5 -13.9 235 43 22 7.8 4.3
26000 -23.2 -9.8 235 43 22 7.8 4.3 | -23.2 -9.8 235 42 22 7.8 4.3
25000 -20.9 -5.6 235 42 22 7.5 4.1 | -20.9 -5.6 240 41 21 7.7 4.2
24000 -18.8 -1.8 240 39 20 7.1 3.9 | -18.7 -1.7 240 39 20 7.6 4.1
23000 -16.7 1.9 245 36 18 7.2 3.9 | -16.4 2.5 240 36 18 7.6 4.2
22000 -14.6 5.7 250 33 17 7.7 4.2 | -14.2 6.4 240 33 17 7.8 4.3
21000 -12.2 10.0 245 31 16 8.2 4.5 | -11.9 10.6 240 30 15 8.0 4.4
20000 -9.8 14.4 245 29 15 8.2 4.5 | -9.5 14.9 240 27 14 8.1 4.4
19500 -8.6 16.5 245 27 14 8.3 4.5 | -8.4 16.9 235 26 13 8.1 4.4
19000 -7.3 18.9 245 27 14 9.2 5.1 | -7.1 19.2 235 24 13 8.8 4.8
18500 -6.0 21.2 245 26 14 9.2 5.0 | -5.9 21.4 230 23 12 8.8 4.8
18000 -4.6 23.7 240 26 13 9.3 5.1 | -4.6 23.7 225 21 11 9.2 5.1
17500 -3.2 26.2 240 26 13 9.3 5.1 | -3.2 26.2 225 21 11 9.5 5.2
17000 -1.8 28.8 240 26 13 9.3 5.1 | -1.7 28.9 225 20 10 9.5 5.2
16500 -0.5 31.1 235 25 13 9.2 5.1 | -0.3 31.5 220 20 10 9.6 5.3
16000 0.9 33.6 235 25 13 9.2 5.1 | 1.1 34.0 220 20 10 9.6 5.3
15500 2.3 36.1 230 25 13 9.4 5.1 | 2.6 36.7 215 20 10 9.8 5.3
15000 4.4 39.9 225 25 13 9.4 5.2 | 4.0 39.2 215 19 10 9.8 5.4
14500 5.7 42.3 225 24 12 9.4 5.1 | 6.2 43.2 215 19 10 9.4 5.1
14000 7.1 44.8 220 24 12 9.4 5.1 | 7.6 45.7 210 19 10 9.4 5.1
13500 8.5 47.3 215 23 12 9.6 5.2 | 9.0 48.2 210 19 10 9.7 5.3
13000 9.9 49.8 210 22 12 9.6 5.3 | 10.5 50.9 210 19 10 9.8 5.4
12500 11.3 52.3 205 22 11 9.3 5.1 | 11.9 53.4 210 18 9 9.6 5.3
12000 12.6 54.7 200 21 11 9.1 5.0 | 13.3 55.9 205 18 9 9.4 5.1
11500 13.9 57.0 195 20 10 8.9 4.9 | 14.7 58.5 200 17 9 9.3 5.1
11000 15.2 59.4 185 18 9 8.4 4.6 | 16.0 60.8 200 16 8 9.0 4.9
10500 16.4 61.5 175 17 9 5.1 2.8 | 17.4 63.3 195 16 8 6.2 3.4
10250 16.6 61.9 175 16 8 5.2 2.8 | 17.7 63.9 195 15 8 6.5 3.6
10000 17.2 63.0 170 15 8 9.7 5.3 | 18.4 65.1 195 15 8 10.5 5.8
9750 17.8 64.0 160 14 7 9.0 4.9 | 19.1 66.4 195 14 7 9.7 5.3
9500 18.4 65.1 150 13 7 7.6 4.2 | 19.8 67.6 190 13 7 8.9 4.9
9250 18.8 65.8 140 12 6 5.9 3.2 | 20.3 68.5 190 12 6 7.0 3.8
9000 19.3 66.7 140 11 6 6.8 3.7 | 20.8 69.4 190 11 6 6.8 3.8
8750 19.7 67.5 135 10 5 6.7 3.7 | 21.3 70.3 190 10 5 6.8 3.8
8500 20.2 68.4 130 9 5 7.4 4.1 | 21.8 71.2 190 8 4 7.2 4.0
8250 20.8 69.4 125 8 4 9.5 5.2 | 22.3 72.1 190 7 4 7.9 4.3
8000 21.5 70.7 120 8 4 6.5 3.6 | 22.8 73.0 190 6 3 7.2 4.0
7750 22.2 72.0 120 7 4 19.7 10.8 | 23.3 73.9 195 4 2 6.2 3.4
7500 22.1 71.8 120 7 4 -61.5 -33.7 | 23.8 74.8 205 3 2 7.6 4.2
7250 12.8 55.0 115 7 4 -99.0 -54.3 | 24.4 75.9 225 3 1 9.0 4.9
7000 3.5 38.3 115 7 3 -10.5 -5.7 | 25.0 77.0 255 2 1 8.5 4.7
6750 12.7 54.9 110 6 3 213.1 116.9 | 25.5 77.9 275 3 1 8.0 4.4
6500 25.8 78.4 110 6 3 98.3 53.9 | 26.1 79.0 290 4 2 9.2 5.1
6250 26.7 80.1 110 6 3 -12.6 -6.9 | 26.9 80.4 290 4 2 10.3 5.7
6000 27.5 81.5 105 5 3 18.1 9.9 | 27.6 81.7 295 4 2 9.9 5.4
5750 28.5 83.3 105 5 3 13.4 7.4 | 28.3 82.9 300 5 2 9.7 5.3
5500 30.0 86.0 090 4 2 30.7 16.9 | 29.0 84.2 300 5 3 9.8 5.4
________________________________________________________________________________
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.
CIN (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: Jun 3rd, 2013 13:59 UTC