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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 231241
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
0641 MDT Wednesday, May 23, 2018
This forecast is for Wednesday, May 23, 2018:
If the trigger temperature of 70.6 F/21.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1430 ft/min (7.3 m/s)
Maximum height of thermals.................. 20054 ft MSL (15211 ft AGL)
Forecast maximum temperature................... 82.0 F/28.2 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................. 14416 ft MSL (9574 ft AGL)
Thermal soaring outlook for Thursday 05/24..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:54:58 / 20:26:40 MDT
Total possible sunshine........... 14 hr 31 min 42 sec (871 min 42 sec)
Altitude of sun at 13:11:01 MDT... 71.54 degrees
Upper air data from rawinsonde observation taken on 05/23/2018 at 0600 MDT
Freezing level.................. 12788 ft MSL (7945 ft AGL)
Convective condensation level... 13140 ft MSL (8297 ft AGL)
Lifted condensation level....... 14755 ft MSL (9912 ft AGL)
Lifted index.................... -5.8
K index......................... +20.6
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 -57.0 -70.6 210 18 9 -5.6 -3.0 104.0 219.3 43.7 M M
45000 -56.6 -69.9 205 37 19 2.5 1.3 80.0 176.0 32.0 M M
40000 -55.3 -67.5 205 56 29 2.8 1.5 58.0 136.3 19.9 M M
38000 -53.4 -64.1 205 65 34 3.1 1.7 51.8 125.2 16.3 M M
36000 -51.4 -60.5 205 72 37 5.3 2.9 46.5 115.7 13.0 M M
34000 -48.9 -56.0 205 60 31 2.7 1.5 41.7 107.1 9.9 M M
32000 -45.8 -50.4 205 50 26 7.7 4.2 37.8 100.1 7.3 M M
30000 -40.7 -41.3 205 44 23 9.1 5.0 36.0 96.7 6.2 M M
29000 -38.0 -36.4 205 43 22 9.0 4.9 35.6 96.1 6.0 M M
28000 -35.3 -31.5 205 43 22 9.1 5.0 35.3 95.6 5.8 M M
27000 -32.9 -27.2 210 42 22 7.6 4.2 34.6 94.3 5.3 M M
26000 -30.7 -23.3 210 42 21 7.7 4.2 33.8 92.8 4.7 M M
25000 -28.4 -19.1 210 41 21 7.7 4.2 33.1 91.6 4.2 M M
24000 -26.0 -14.8 215 39 20 8.3 4.5 32.4 90.4 3.7 M M
23000 -24.2 -11.6 210 36 19 0.1 0.0 31.2 88.1 2.7 M M
22000 -22.4 -8.3 215 37 19 8.2 4.5 29.7 85.5 1.6 M M
21000 -20.1 -4.2 220 39 20 7.2 3.9 29.0 84.3 1.0 M M
20000 -18.2 -0.8 205 42 21 4.8 2.6 28.0 82.3 0.0 M M
19500 -17.4 0.7 205 44 23 5.9 3.3 27.2 81.0 -0.7 1393 7.1
19000 -16.5 2.3 200 47 24 5.6 3.1 26.6 79.8 -1.3 1352 6.9
18500 -15.4 4.3 200 44 23 9.6 5.3 26.2 79.1 -1.6 1304 6.6
18000 -14.0 6.8 205 42 21 9.2 5.1 26.1 78.9 -1.7 1248 6.3
17500 -12.7 9.1 205 39 20 8.9 4.9 26.0 78.8 -1.8 1192 6.1
17000 -11.4 11.5 210 37 19 8.7 4.8 25.8 78.4 -2.0 1139 5.8
16500 -9.5 14.9 210 34 18 8.7 4.8 25.5 78.0 -2.3 1059 5.4
16000 -8.2 17.2 215 32 17 8.7 4.8 25.4 77.7 -2.4 1005 5.1
15500 -6.9 19.6 215 30 15 8.7 4.8 25.2 77.3 -2.6 952 4.8
15000 -5.6 21.9 210 27 14 8.7 4.8 25.0 77.0 -2.8 899 4.6
14500 -4.3 24.3 210 25 13 8.8 4.8 24.8 76.7 -3.0 845 4.3
14000 -3.0 26.6 205 22 12 8.8 4.8 24.7 76.5 -3.2 791 4.0
13500 -1.7 28.9 205 19 10 8.8 4.8 24.5 76.2 -3.4 738 3.7
13000 -0.4 31.3 205 16 8 8.8 4.8 24.4 75.9 -3.6 684 3.5
12500 0.9 33.6 200 12 6 8.8 4.8 24.2 75.6 -3.7 631 3.2
12000 2.2 36.0 200 9 5 8.8 4.9 24.1 75.4 -3.9 577 2.9
11500 3.5 38.3 195 10 5 8.9 4.9 23.9 75.1 -4.1 524 2.7
11000 4.7 40.5 190 11 5 8.1 4.5 23.8 74.8 -4.3 471 2.4
10500 5.8 42.4 185 11 6 7.7 4.2 23.4 74.2 -4.7 423 2.1
10250 6.4 43.5 180 12 6 8.1 4.4 23.3 73.9 -4.9 399 2.0
10000 7.0 44.6 180 12 6 8.9 4.9 23.2 73.8 -5.0 374 1.9
9750 7.6 45.7 170 13 7 9.0 4.9 23.1 73.6 -5.1 347 1.8
9500 8.3 46.9 165 15 8 9.2 5.0 23.1 73.5 -5.2 320 1.6
9250 8.9 48.0 160 16 8 6.4 3.5 23.0 73.3 -5.4 295 1.5
9000 9.3 48.7 155 18 9 7.0 3.8 22.6 72.8 -5.7 277 1.4
8750 9.5 49.1 155 17 9 -3.9 -2.2 22.2 72.0 -6.2 261 1.3
8500 8.8 47.8 160 16 8 -6.0 -3.3 20.7 69.3 -7.7 275 1.4
8250 8.9 48.0 160 15 8 6.6 3.6 20.2 68.3 -8.3 264 1.3
8000 9.4 48.9 165 14 7 6.8 3.7 19.9 67.9 -8.5 242 1.2
7750 9.8 49.6 160 13 7 1.6 0.9 19.6 67.2 -8.9 224 1.1
7500 9.7 49.5 155 11 6 0.0 0.0 18.8 65.8 -9.8 220 1.1
7250 9.9 49.8 145 10 5 5.9 3.2 18.3 64.9 -10.4 207 1.1
7000 10.4 50.7 135 9 5 7.5 4.1 18.1 64.5 -10.6 184 0.9
6750 10.9 51.6 130 9 5 7.0 3.9 17.9 64.2 -10.8 160 0.8
6500 11.5 52.7 120 9 4 7.1 3.9 17.7 63.8 -11.0 137 0.7
6250 12.0 53.6 110 9 4 7.2 4.0 17.5 63.5 -11.3 114 0.6
6000 12.5 54.5 100 9 5 6.8 3.7 17.3 63.1 -11.5 91 0.5
5750 13.0 55.4 100 8 4 8.3 4.6 17.1 62.8 -11.7 67 0.3
5500 13.6 56.5 095 7 4 2.6 1.4 16.9 62.4 -11.9 44 0.2
5250 13.4 56.1 095 7 3 -3.6 -2.0 16.0 60.8 -12.9 42 0.2
5000 13.0 55.4 090 6 3 -8.1 -4.4 14.9 58.9 -14.0 45 0.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/23/2018 at 0900 MDT | 05/23/2018 at 1200 MDT
|
K index... +24.2 LI... -1.1 | K index... +25.8 LI... -1.4
CAPE... +41.8 CIN... -69.8 | CAPE... +109.7 CIN... -19.9
|
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 -57.7 -71.9 210 24 12 0.6 0.3 | -58.1 -72.6 215 27 14 0.4 0.2
45000 -56.8 -70.2 215 35 18 1.1 0.6 | -57.4 -71.3 220 38 20 1.4 0.8
40000 -55.0 -67.0 220 64 33 1.0 0.6 | -55.1 -67.2 225 65 33 1.2 0.7
38000 -52.6 -62.7 215 70 36 4.6 2.5 | -52.5 -62.5 225 71 36 5.1 2.8
36000 -49.9 -57.8 215 76 39 4.6 2.5 | -49.5 -57.1 225 76 39 5.1 2.8
34000 -47.1 -52.8 215 74 38 4.8 2.6 | -46.5 -51.7 220 76 39 4.8 2.6
32000 -44.3 -47.7 215 62 32 4.8 2.6 | -43.6 -46.5 225 66 34 4.8 2.6
30000 -40.8 -41.4 215 52 27 7.5 4.1 | -40.3 -40.5 225 58 30 6.7 3.7
29000 -38.6 -37.5 220 49 25 7.5 4.1 | -37.8 -36.0 225 52 27 6.6 3.6
28000 -35.8 -32.4 220 44 23 7.5 4.1 | -35.9 -32.6 225 48 25 6.7 3.7
27000 -33.5 -28.3 220 42 22 7.9 4.3 | -33.7 -28.7 230 45 23 7.7 4.2
26000 -31.1 -24.0 220 41 21 7.9 4.3 | -31.4 -24.5 230 43 22 7.7 4.2
25000 -28.8 -19.8 220 40 20 7.9 4.3 | -29.1 -20.4 230 40 21 7.7 4.2
24000 -26.5 -15.7 220 38 20 7.2 4.0 | -26.7 -16.1 230 39 20 8.4 4.6
23000 -24.3 -11.7 215 36 19 7.3 4.0 | -24.2 -11.6 225 38 19 8.3 4.6
22000 -22.1 -7.8 215 34 17 7.3 4.0 | -21.8 -7.2 225 37 19 8.3 4.6
21000 -20.1 -4.2 215 32 17 6.2 3.4 | -19.5 -3.1 225 36 19 6.6 3.6
20000 -18.2 -0.8 210 32 16 6.3 3.4 | -17.6 0.3 225 34 18 6.6 3.6
19500 -17.3 0.9 210 31 16 6.3 3.4 | -16.6 2.1 220 33 17 6.6 3.6
19000 -16.3 2.7 210 31 16 6.3 3.4 | -15.7 3.7 220 33 17 6.6 3.6
18500 -15.4 4.3 205 31 16 7.1 3.9 | -14.7 5.5 220 31 16 6.7 3.7
18000 -14.4 6.1 205 31 16 7.1 3.9 | -13.7 7.3 220 29 15 6.7 3.7
17500 -13.3 8.1 205 30 16 7.9 4.4 | -12.7 9.1 220 26 14 7.3 4.0
17000 -12.1 10.2 205 28 14 8.3 4.6 | -11.7 10.9 220 24 13 7.6 4.2
16500 -10.9 12.4 200 26 13 8.5 4.7 | -10.6 12.9 225 22 12 7.7 4.2
16000 -9.7 14.5 200 24 12 8.8 4.9 | -9.4 15.1 220 21 11 7.9 4.3
15500 -8.4 16.9 200 22 11 8.8 4.8 | -8.3 17.1 220 19 10 7.9 4.3
15000 -7.1 19.2 200 20 10 9.3 5.1 | -7.1 19.2 215 18 9 8.2 4.5
14500 -5.7 21.7 200 19 10 9.3 5.1 | -5.9 21.4 215 17 9 8.1 4.5
14000 -4.3 24.3 205 18 9 9.2 5.1 | -4.0 24.8 215 16 8 9.0 4.9
13500 -2.3 27.9 205 16 8 9.2 5.0 | -2.7 27.1 215 16 8 9.0 4.9
13000 -1.0 30.2 205 15 8 8.8 4.8 | -1.3 29.7 215 15 8 9.3 5.1
12500 0.4 32.7 210 14 7 8.8 4.8 | 0.0 32.0 215 15 8 9.3 5.1
12000 1.6 34.9 215 13 7 8.7 4.8 | 1.4 34.5 215 14 7 9.1 5.0
11500 2.9 37.2 215 13 7 8.9 4.9 | 2.8 37.0 215 13 7 9.1 5.0
11000 4.1 39.4 220 12 6 7.7 4.2 | 4.1 39.4 215 13 7 8.6 4.7
10500 5.3 41.5 220 12 6 8.3 4.6 | 5.4 41.7 215 12 6 5.1 2.8
10250 5.9 42.6 220 12 6 5.7 3.1 | 5.7 42.3 220 12 6 5.6 3.1
10000 6.2 43.2 220 11 6 6.0 3.3 | 6.4 43.5 220 11 6 10.7 5.9
9750 6.8 44.2 220 11 6 8.8 4.8 | 7.1 44.8 220 10 5 9.4 5.2
9500 7.4 45.3 220 11 6 8.1 4.5 | 7.8 46.0 220 10 5 9.5 5.2
9250 8.0 46.4 220 11 6 6.5 3.6 | 8.4 47.1 220 9 5 8.0 4.4
9000 8.4 47.1 220 11 6 6.2 3.4 | 9.0 48.2 225 8 4 8.4 4.6
8750 8.9 48.0 220 11 5 7.5 4.1 | 9.7 49.5 225 7 4 9.4 5.2
8500 9.5 49.1 220 11 5 6.9 3.8 | 10.3 50.5 230 7 3 9.2 5.0
8250 9.9 49.8 215 11 5 5.9 3.2 | 11.0 51.8 230 6 3 9.1 5.0
8000 10.3 50.5 215 10 5 5.2 2.9 | 11.6 52.9 235 6 3 9.3 5.1
7750 10.7 51.3 210 10 5 5.4 3.0 | 12.4 54.3 235 6 3 9.4 5.2
7500 11.1 52.0 205 10 5 5.0 2.7 | 13.1 55.6 235 6 3 9.9 5.4
7250 11.5 52.7 205 10 5 4.5 2.5 | 13.8 56.8 240 6 3 10.7 5.9
7000 11.8 53.2 200 9 5 4.3 2.4 | 14.6 58.3 240 6 3 10.3 5.6
6750 12.1 53.8 200 8 4 3.9 2.1 | 15.4 59.7 240 6 3 9.9 5.4
6500 12.4 54.3 200 7 3 7.5 4.1 | 16.1 61.0 240 6 3 10.9 6.0
6250 13.1 55.6 200 6 3 10.6 5.8 | 17.0 62.6 240 6 3 12.0 6.6
6000 13.8 56.8 200 6 3 9.1 5.0 | 17.9 64.2 245 6 3 10.4 5.7
5750 14.4 57.9 200 5 3 9.7 5.3 | 18.6 65.5 245 6 3 12.5 6.9
5500 15.2 59.4 205 5 2 11.5 6.3 | 19.8 67.6 245 6 3 17.1 9.4
5250 16.1 61.0 205 5 2 11.5 6.3 | 21.0 69.8 245 6 3 16.0 8.8
5000 M M M M M M M | M M M M M M M
05/23/2018 at 1500 MDT | 05/23/2018 at 1800 MDT
|
K index... +26.0 LI... -0.9 | K index... +28.0 LI... -1.0
CAPE... +34.7 CIN... -41.9 | CAPE... +80.9 CIN... -27.7
|
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 -58.8 -73.8 220 25 13 0.3 0.2 | -58.6 -73.5 225 21 11 0.9 0.5
45000 -58.0 -72.4 230 36 19 1.6 0.9 | -57.2 -71.0 235 31 16 1.0 0.6
40000 -55.6 -68.1 235 60 31 1.3 0.7 | -55.7 -68.3 245 57 29 0.8 0.4
38000 -53.0 -63.4 235 64 33 4.8 2.7 | -53.6 -64.5 240 58 30 3.9 2.1
36000 -50.1 -58.2 230 68 35 4.8 2.7 | -51.2 -60.2 240 58 30 3.9 2.1
34000 -47.0 -52.6 230 65 34 5.3 2.9 | -48.1 -54.6 240 54 28 6.7 3.7
32000 -43.8 -46.8 235 56 29 5.3 2.9 | -44.1 -47.4 240 46 24 6.7 3.7
30000 -39.5 -39.1 240 47 24 7.6 4.2 | -39.2 -38.6 245 41 21 7.8 4.3
29000 -37.3 -35.1 245 44 23 7.6 4.2 | -36.9 -34.4 245 41 21 7.8 4.3
28000 -35.0 -31.0 245 41 21 7.6 4.2 | -34.5 -30.1 250 40 21 7.8 4.3
27000 -32.6 -26.7 250 39 20 8.2 4.5 | -32.1 -25.8 250 39 20 8.3 4.6
26000 -30.2 -22.4 245 38 19 8.2 4.5 | -29.6 -21.3 245 38 19 8.3 4.6
25000 -27.7 -17.9 245 36 19 8.2 4.5 | -27.1 -16.8 245 36 19 8.3 4.6
24000 -25.2 -13.4 240 34 18 8.3 4.6 | -24.7 -12.5 245 34 18 7.7 4.2
23000 -22.7 -8.9 240 33 17 8.3 4.6 | -22.4 -8.3 240 32 17 7.7 4.2
22000 -20.3 -4.5 235 31 16 8.2 4.5 | -20.1 -4.2 240 31 16 7.7 4.2
21000 -18.1 -0.6 235 30 16 6.1 3.3 | -18.0 -0.4 235 30 15 6.8 3.7
20000 -16.4 2.5 235 31 16 6.1 3.3 | -16.0 3.2 235 29 15 6.9 3.8
19500 -15.5 4.1 235 32 16 6.1 3.4 | -15.0 5.0 235 29 15 7.0 3.8
19000 -14.6 5.7 230 32 17 6.4 3.5 | -14.0 6.8 235 29 15 7.4 4.1
18500 -13.6 7.5 230 31 16 7.5 4.1 | -12.8 9.0 235 27 14 8.5 4.7
18000 -12.5 9.5 230 30 16 7.5 4.1 | -11.6 11.1 235 25 13 8.5 4.7
17500 -11.4 11.5 225 29 15 8.2 4.5 | -10.4 13.3 230 24 12 8.4 4.6
17000 -10.2 13.6 220 27 14 8.4 4.6 | -9.2 15.4 230 23 12 8.4 4.6
16500 -9.0 15.8 215 26 13 8.5 4.7 | -8.0 17.6 225 22 11 8.2 4.5
16000 -7.8 18.0 215 25 13 8.7 4.8 | -6.8 19.8 225 21 11 7.9 4.4
15500 -6.5 20.3 210 24 12 8.8 4.8 | -5.7 21.7 220 20 11 7.9 4.3
15000 -5.3 22.5 210 23 12 7.6 4.2 | -4.5 23.9 220 20 10 7.6 4.2
14500 -3.6 25.5 205 22 11 7.9 4.3 | -2.8 27.0 220 18 9 8.2 4.5
14000 -2.4 27.7 205 21 11 8.1 4.5 | -1.5 29.3 220 17 9 8.9 4.9
13500 -1.2 29.8 205 20 10 8.2 4.5 | -0.2 31.6 215 17 9 8.9 4.9
13000 0.1 32.2 205 19 10 9.0 4.9 | 1.1 34.0 215 16 8 8.4 4.6
12500 1.4 34.5 205 18 9 8.9 4.9 | 2.4 36.3 220 15 8 8.5 4.7
12000 2.6 36.7 205 17 9 7.6 4.2 | 3.7 38.7 220 14 7 9.0 4.9
11500 3.8 38.8 210 15 8 7.7 4.2 | 5.0 41.0 220 13 7 9.0 4.9
11000 4.9 40.8 210 13 7 7.8 4.3 | 6.2 43.2 225 12 6 7.9 4.3
10500 6.1 43.0 215 11 6 4.4 2.4 | 7.4 45.3 230 11 6 11.3 6.2
10250 6.3 43.3 220 10 5 5.0 2.8 | 8.4 47.1 230 11 5 11.3 6.2
10000 7.0 44.6 225 9 5 10.1 5.5 | 9.0 48.2 235 10 5 6.9 3.8
9750 7.7 45.9 230 9 5 8.8 4.8 | 9.5 49.1 235 9 5 8.1 4.5
9500 8.3 46.9 240 8 4 9.1 5.0 | 10.1 50.2 240 9 5 7.6 4.2
9250 9.0 48.2 245 8 4 8.7 4.8 | 10.7 51.3 245 8 4 7.0 3.9
9000 9.6 49.3 250 8 4 8.7 4.8 | 11.2 52.2 250 7 4 7.4 4.1
8750 10.3 50.5 255 8 4 8.9 4.9 | 11.8 53.2 260 6 3 7.8 4.3
8500 10.9 51.6 260 8 4 9.0 4.9 | 12.3 54.1 270 5 3 7.9 4.3
8250 11.6 52.9 265 8 4 9.2 5.1 | 12.9 55.2 280 5 2 8.4 4.6
8000 12.3 54.1 265 8 4 9.7 5.3 | 13.6 56.5 290 5 2 9.0 4.9
7750 13.1 55.6 265 8 4 9.9 5.4 | 14.3 57.7 290 5 2 9.2 5.1
7500 13.8 56.8 270 8 4 10.1 5.5 | 15.0 59.0 295 5 2 9.6 5.3
7250 14.6 58.3 270 8 4 10.6 5.8 | 15.7 60.3 295 5 2 10.3 5.7
7000 15.4 59.7 270 8 4 10.1 5.5 | 16.5 61.7 295 5 2 9.8 5.3
6750 16.1 61.0 270 8 4 9.6 5.3 | 17.2 63.0 295 5 2 9.1 5.0
6500 16.8 62.2 270 8 4 10.8 6.0 | 17.9 64.2 295 5 2 10.2 5.6
6250 17.7 63.9 270 8 4 12.3 6.8 | 18.7 65.7 295 5 2 11.0 6.1
6000 18.6 65.5 270 8 4 10.0 5.5 | 19.5 67.1 295 5 2 10.5 5.7
5750 19.3 66.7 275 8 4 11.7 6.4 | 20.3 68.5 295 4 2 10.6 5.8
5500 20.4 68.7 270 8 4 17.1 9.4 | 21.1 70.0 295 4 2 11.4 6.3
5250 21.7 71.1 270 8 4 16.0 8.8 | 22.0 71.6 295 5 2 11.4 6.2
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.
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
- National Weather Service
- Bismarck, ND Weather Forecast Office
- 2301 University Drive, Building 27
- Bismarck, ND 58504
- 701-250-4224
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- Page last modified: Mar 8th, 2018 20:36 UTC