699
UXUS97 KBOU 100008
SRGBOU
SOARING FORECAST
NATIONAL WEATHER SERVICE DENVER/BOULDER, COLORADO
1807 MDT THURSDAY, APRIL 9, 2026
THIS FORECAST IS FOR FRIDAY, APRIL 10, 2026:
IF THE TRIGGER TEMPERATURE OF 60.7 F/15.9 C IS REACHED...THEN
THERMAL SOARING INDEX....................... FAIR
MAXIMUM RATE OF LIFT........................ 232 FT/MIN (1.2 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 11823 FT MSL (6526 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 70.0 F/21.6 C
TIME OF TRIGGER TEMPERATURE.................... 1145 MDT
TIME OF OVERDEVELOPMENT........................ 1400 MDT
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................. 9973 FT MSL (4677 FT AGL)
THERMAL SOARING OUTLOOK FOR SATURDAY 04/11..... 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)................ NEITHER
POTENTIAL HEIGHT OF WAVE....................... 39534 FT MSL (34237 FT AGL)
WAVE SOARING OUTLOOK FOR SATURDAY 04/11........ POOR
REMARKS...
SUNRISE/SUNSET.................... 06:28:50 / 19:32:32 MDT
TOTAL POSSIBLE SUNSHINE........... 13 HR 3 MIN 42 SEC (783 MIN 42 SEC)
ALTITUDE OF SUN AT 13:00:41 MDT... 58.40 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 04/10/2026 AT 0600 MDT
FREEZING LEVEL.................. 12426 FT MSL (7129 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 13077 FT MSL (7780 FT AGL)
LIFTED CONDENSATION LEVEL....... 12871 FT MSL (7574 FT AGL)
LIFTED INDEX.................... -3.6
K INDEX......................... +23.3
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 -60.9 -77.6 265 38 19 0.9 0.5 M M M M M
45000 -59.6 -75.3 260 37 19 -2.3 -1.3 M M M M M
40000 -64.9 -84.8 265 50 26 -3.6 -2.0 M M M M M
38000 -63.0 -81.4 265 50 26 7.8 4.3 M M M M M
36000 -58.3 -72.9 265 47 24 7.8 4.3 M M M M M
34000 -53.5 -64.3 265 44 23 8.7 4.8 M M M M M
32000 -47.6 -53.7 265 39 20 8.7 4.8 M M M M M
30000 -42.6 -44.7 260 35 18 8.0 4.4 32.9 91.1 8.8 M M
29000 -40.2 -40.4 260 32 17 8.0 4.4 32.1 89.8 8.4 M M
28000 -37.8 -36.0 260 30 15 8.0 4.4 31.5 88.7 8.0 M M
27000 -35.4 -31.7 255 29 15 7.9 4.4 30.9 87.6 7.6 M M
26000 -33.0 -27.4 255 29 15 7.9 4.4 30.1 86.2 7.1 M M
25000 -30.6 -23.1 255 29 15 8.0 4.4 29.5 85.0 6.6 M M
24000 -28.3 -18.9 255 29 15 7.7 4.2 28.8 83.9 6.2 M M
23000 -25.9 -14.6 260 27 14 7.7 4.2 28.0 82.4 5.6 M M
22000 -23.6 -10.5 265 25 13 7.7 4.2 27.3 81.2 5.1 M M
21000 -21.3 -6.3 265 24 12 7.4 4.1 26.6 79.9 4.5 M M
20000 -19.1 -2.4 270 23 12 7.5 4.1 25.7 78.3 3.8 M M
19500 -18.0 -0.4 270 23 12 7.5 4.1 25.3 77.6 3.5 M M
19000 -16.9 1.6 270 23 12 7.5 4.1 25.0 77.0 3.2 M M
18500 -15.8 3.6 270 22 12 8.0 4.4 24.7 76.4 2.9 M M
18000 -14.6 5.7 270 22 11 8.0 4.4 24.3 75.8 2.6 M M
17500 -13.5 7.7 270 22 11 8.3 4.6 24.1 75.3 2.3 M M
17000 -12.2 10.0 270 20 10 8.6 4.7 23.8 74.9 2.1 M M
16500 -10.3 13.5 270 19 10 9.3 5.1 23.6 74.4 1.8 M M
16000 -8.9 16.0 270 18 9 9.4 5.2 23.5 74.3 1.7 M M
15500 -7.6 18.3 270 17 9 9.2 5.0 23.5 74.2 1.7 M M
15000 -6.2 20.8 270 17 9 8.9 4.9 23.3 74.0 1.5 M M
14500 -4.9 23.2 265 17 9 8.8 4.8 23.2 73.7 1.4 M M
14000 -3.7 25.3 260 17 9 8.3 4.5 23.0 73.3 1.2 M M
13500 -2.4 27.7 255 17 9 8.3 4.6 22.7 72.9 1.0 M M
13000 -1.2 29.8 245 17 9 8.0 4.4 22.5 72.5 0.7 M M
12500 -0.0 32.0 240 17 9 8.2 4.5 22.2 72.0 0.5 M M
12000 1.1 34.0 235 17 9 6.9 3.8 21.9 71.3 0.1 M M
11500 2.1 35.8 230 16 8 7.4 4.0 21.4 70.5 -0.3 398 2.0
11000 2.9 37.2 225 15 8 3.7 2.1 20.8 69.4 -1.0 359 1.8
10500 3.4 38.1 220 13 7 4.3 2.3 19.8 67.7 -1.9 328 1.7
10250 3.7 38.7 220 13 6 2.8 1.5 19.4 66.9 -2.4 312 1.6
10000 3.8 38.8 220 12 6 0.6 0.3 18.7 65.7 -3.0 301 1.5
9750 3.8 38.8 215 11 5 0.5 0.3 18.0 64.4 -3.7 293 1.5
9500 3.9 39.0 215 9 5 0.5 0.3 17.3 63.1 -4.4 285 1.4
9250 3.9 39.0 210 8 4 0.2 0.1 16.5 61.8 -5.1 277 1.4
9000 3.9 39.0 210 7 4 0.4 0.2 15.8 60.4 -5.9 270 1.4
8750 3.9 39.0 205 6 3 1.1 0.6 15.1 59.2 -6.6 262 1.3
8500 4.0 39.2 200 5 3 2.0 1.1 14.4 58.0 -7.3 253 1.3
8250 4.1 39.4 200 5 3 3.6 2.0 13.9 57.0 -7.9 240 1.2
8000 4.4 39.9 200 6 3 4.0 2.2 13.5 56.2 -8.4 225 1.1
7750 4.7 40.5 195 6 3 5.4 3.0 13.0 55.5 -8.8 209 1.1
7500 5.1 41.2 190 7 3 4.3 2.4 12.7 54.9 -9.2 190 1.0
7250 5.2 41.4 175 6 3 2.0 1.1 12.2 53.9 -9.8 177 0.9
7000 5.4 41.7 160 7 3 2.7 1.5 11.6 52.9 -10.4 165 0.8
6750 5.6 42.1 145 7 4 1.7 0.9 11.1 51.9 -11.0 153 0.8
6500 5.7 42.3 135 8 4 2.4 1.3 10.4 50.8 -11.7 143 0.7
6250 5.9 42.6 125 8 4 3.6 2.0 10.0 49.9 -12.2 128 0.6
6000 6.2 43.2 115 9 4 3.9 2.1 9.5 49.1 -12.7 112 0.6
5750 6.5 43.7 110 9 4 4.1 2.3 9.1 48.3 -13.1 95 0.5
5500 6.7 44.1 105 7 3 2.1 1.2 8.6 47.4 -13.6 81 0.4
* * * * * * NUMERICAL WEATHER PREDICTION MODEL FORECAST DATA VALID * * * * * *
04/10/2026 AT 0900 MDT | 04/10/2026 AT 1200 MDT
|
CAPE... +0.3 LI... +0.4 | CAPE... +32.4 LI... -0.5
CINH... -0.0 K INDEX... +17.3 | CINH... -106.3 K INDEX... +19.5
|
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 -61.0 -77.8 265 38 20 0.6 0.3 | -60.3 -76.5 260 38 20 0.1 0.1
45000 -60.2 -76.4 255 46 24 -2.0 -1.1 | -60.2 -76.4 260 47 24 -2.1 -1.1
40000 -64.8 -84.6 260 55 28 -3.2 -1.7 | -65.1 -85.2 255 59 30 -3.3 -1.8
38000 -62.7 -80.9 255 54 28 7.8 4.3 | -62.9 -81.2 255 58 30 8.2 4.5
36000 -58.1 -72.6 255 49 25 7.8 4.3 | -57.3 -71.1 255 53 27 8.2 4.5
34000 -52.6 -62.7 255 44 23 8.5 4.7 | -52.4 -62.3 250 49 25 8.2 4.5
32000 -47.5 -53.5 255 40 21 8.5 4.7 | -47.5 -53.5 250 44 23 8.2 4.5
30000 -42.5 -44.5 255 36 19 8.5 4.6 | -42.4 -44.3 250 40 20 8.6 4.7
29000 -39.9 -39.8 255 35 18 8.5 4.7 | -39.9 -39.8 250 37 19 8.6 4.7
28000 -37.4 -35.3 255 34 17 8.5 4.6 | -37.3 -35.1 255 35 18 8.6 4.7
27000 -34.9 -30.8 255 32 17 7.7 4.2 | -34.8 -30.6 255 33 17 7.5 4.1
26000 -32.6 -26.7 260 31 16 7.7 4.3 | -32.5 -26.5 255 32 17 7.5 4.1
25000 -30.3 -22.5 260 30 16 7.8 4.3 | -30.3 -22.5 255 31 16 7.6 4.1
24000 -28.0 -18.4 265 29 15 7.5 4.1 | -28.1 -18.6 255 30 15 6.9 3.8
23000 -25.7 -14.3 265 29 15 7.6 4.1 | -26.0 -14.8 255 28 14 7.0 3.8
22000 -23.5 -10.3 265 29 15 7.6 4.1 | -23.9 -11.0 255 26 13 7.0 3.8
21000 -21.2 -6.2 270 28 15 7.7 4.2 | -21.6 -6.9 255 24 12 8.2 4.5
20000 -18.9 -2.0 265 27 14 7.7 4.2 | -19.2 -2.6 255 23 12 8.2 4.5
19500 -17.7 0.1 265 27 14 7.7 4.2 | -17.4 0.7 250 23 12 8.2 4.5
19000 -16.6 2.1 265 26 13 7.7 4.2 | -16.2 2.8 250 22 11 8.6 4.7
18500 -14.8 5.4 265 25 13 8.0 4.4 | -14.9 5.2 250 22 11 8.8 4.8
18000 -13.6 7.5 265 24 12 8.0 4.4 | -13.6 7.5 250 21 11 8.8 4.8
17500 -12.4 9.7 270 23 12 8.5 4.7 | -12.3 9.9 250 21 11 8.7 4.8
17000 -11.1 12.0 270 22 11 8.4 4.6 | -11.0 12.2 245 20 11 8.7 4.8
16500 -9.9 14.2 270 21 11 8.8 4.8 | -9.7 14.5 245 20 10 9.1 5.0
16000 -8.6 16.5 270 20 10 8.9 4.9 | -8.4 16.9 245 19 10 9.1 5.0
15500 -7.3 18.9 270 19 10 9.1 5.0 | -7.0 19.4 240 18 9 9.2 5.1
15000 -5.9 21.4 270 18 9 9.3 5.1 | -5.6 21.9 240 18 9 9.4 5.1
14500 -4.5 23.9 265 17 9 9.3 5.1 | -4.2 24.4 235 17 9 9.3 5.1
14000 -3.2 26.2 265 17 9 9.0 4.9 | -2.9 26.8 235 17 9 9.2 5.0
13500 -1.8 28.8 260 16 8 9.1 5.0 | -1.5 29.3 230 16 8 9.2 5.0
13000 -0.6 30.9 255 16 8 7.4 4.1 | -0.1 31.8 230 16 8 8.9 4.9
12500 0.5 32.9 250 17 9 7.7 4.2 | 1.2 34.2 225 17 9 9.0 4.9
12000 1.5 34.7 240 17 9 6.2 3.4 | 2.5 36.5 225 17 9 8.4 4.6
11500 2.4 36.3 230 18 9 6.5 3.6 | 3.7 38.7 220 18 9 8.6 4.7
11000 3.2 37.8 220 18 9 4.9 2.7 | 4.9 40.8 215 18 9 7.3 4.0
10500 3.9 39.0 215 19 10 5.9 3.2 | 6.0 42.8 215 19 10 8.7 4.8
10250 4.2 39.6 210 19 10 1.2 0.7 | 6.5 43.7 210 19 10 2.4 1.3
10000 4.2 39.6 210 20 10 2.2 1.2 | 6.5 43.7 210 20 10 2.0 1.1
9750 4.6 40.3 205 19 10 7.5 4.1 | 6.9 44.4 210 19 10 8.0 4.4
9500 5.1 41.2 200 19 10 6.3 3.5 | 7.4 45.3 205 19 10 6.7 3.7
9250 5.5 41.9 195 19 10 3.6 2.0 | 7.8 46.0 200 18 9 3.0 1.6
9000 5.6 42.1 195 19 10 1.3 0.7 | 7.8 46.0 200 18 9 0.0 0.0
8750 5.8 42.4 195 18 9 2.9 1.6 | 7.8 46.0 195 16 8 1.8 1.0
8500 5.9 42.6 195 17 9 2.3 1.3 | 7.9 46.2 190 15 8 1.1 0.6
8250 6.0 42.8 195 16 8 0.4 0.2 | 7.9 46.2 180 13 7 -0.8 -0.4
8000 6.0 42.8 195 15 8 -0.3 -0.2 | 7.7 45.9 170 11 6 -1.1 -0.6
7750 5.9 42.6 200 14 7 -2.0 -1.1 | 7.6 45.7 155 9 5 0.3 0.2
7500 5.7 42.3 205 10 5 -4.4 -2.4 | 7.7 45.9 135 8 4 3.3 1.8
7250 5.3 41.5 200 8 4 -4.8 -2.6 | 8.1 46.6 125 7 4 5.8 3.2
7000 4.9 40.8 200 6 3 -4.8 -2.6 | 8.5 47.3 115 7 4 5.3 2.9
6750 4.5 40.1 195 5 2 -4.9 -2.7 | 9.0 48.2 110 8 4 9.5 5.2
6500 4.3 39.7 160 3 1 0.8 0.4 | 9.9 49.8 105 7 4 11.7 6.4
6250 4.6 40.3 140 3 2 5.9 3.2 | 10.7 51.3 100 7 4 10.5 5.7
6000 4.9 40.8 125 3 2 2.2 1.2 | 11.4 52.5 095 7 4 9.1 5.0
5750 5.2 41.4 110 4 2 8.1 4.4 | 12.2 54.0 090 7 4 15.1 8.3
5500 6.4 43.5 105 4 2 24.3 13.3 | 13.9 57.0 090 7 3 31.2 17.1
04/10/2026 AT 1500 MDT | 04/10/2026 AT 1800 MDT
|
CAPE... +221.9 LI... -1.8 | CAPE... +4.4 LI... 0.0
CINH... -112.3 K INDEX... +22.2 | CINH... -0.4 K INDEX... +24.9
|
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 -60.1 -76.2 255 40 20 0.8 0.4 | -60.9 -77.6 250 41 21 0.9 0.5
45000 -58.9 -74.0 255 45 23 -2.0 -1.1 | -59.7 -75.5 250 50 26 -1.9 -1.1
40000 -64.9 -84.8 255 64 33 -3.6 -2.0 | -65.1 -85.2 255 55 28 -3.1 -1.7
38000 -62.3 -80.1 255 64 33 7.9 4.3 | -62.1 -79.8 255 53 27 8.3 4.6
36000 -57.5 -71.5 255 60 31 7.9 4.3 | -57.1 -70.8 255 49 25 8.3 4.6
34000 -52.6 -62.7 255 55 28 8.7 4.8 | -51.9 -61.4 255 43 22 9.2 5.0
32000 -47.4 -53.3 255 47 24 8.7 4.7 | -46.4 -51.5 250 34 17 9.2 5.0
30000 -42.1 -43.8 250 39 20 9.1 5.0 | -40.9 -41.6 250 28 14 9.2 5.0
29000 -39.4 -38.9 250 37 19 9.1 5.0 | -37.5 -35.5 245 28 14 9.2 5.0
28000 -36.0 -32.8 245 33 17 9.1 5.0 | -34.7 -30.5 245 28 14 9.2 5.0
27000 -33.4 -28.1 245 32 16 8.7 4.7 | -32.2 -26.0 240 28 15 8.1 4.4
26000 -30.8 -23.4 240 32 16 8.7 4.7 | -29.8 -21.6 240 29 15 8.1 4.4
25000 -28.2 -18.8 240 31 16 8.7 4.7 | -27.4 -17.3 235 30 16 8.1 4.4
24000 -25.9 -14.6 235 31 16 6.3 3.4 | -25.0 -13.0 235 31 16 7.6 4.1
23000 -24.0 -11.2 230 29 15 6.4 3.5 | -22.8 -9.0 235 32 16 7.6 4.2
22000 -22.1 -7.8 225 28 14 6.5 3.6 | -20.5 -4.9 235 33 17 7.6 4.2
21000 -19.9 -3.8 225 26 13 7.8 4.3 | -18.4 -1.1 230 33 17 6.6 3.6
20000 -17.6 0.3 220 25 13 7.8 4.3 | -16.5 2.3 230 33 17 6.6 3.6
19500 -16.4 2.5 220 24 12 7.8 4.3 | -15.5 4.1 230 34 17 6.6 3.6
19000 -15.3 4.5 215 24 12 7.8 4.3 | -14.5 5.9 230 34 17 6.6 3.6
18500 -14.0 6.8 215 23 12 8.4 4.6 | -13.6 7.5 230 34 17 6.4 3.5
18000 -12.8 9.0 215 22 11 8.4 4.6 | -12.7 9.1 230 33 17 6.4 3.5
17500 -11.5 11.3 215 22 11 8.2 4.5 | -11.7 10.9 230 33 17 6.9 3.8
17000 -10.3 13.5 215 21 11 8.2 4.5 | -10.7 12.7 225 32 17 7.1 3.9
16500 -9.1 15.6 215 21 11 8.3 4.5 | -9.6 14.7 225 31 16 7.1 3.9
16000 -7.9 17.8 210 21 11 8.5 4.7 | -8.6 16.5 225 30 15 6.8 3.7
15500 -6.7 19.9 210 21 11 8.6 4.7 | -7.7 18.1 225 28 15 6.8 3.7
15000 -5.5 22.1 210 21 11 8.4 4.6 | -6.1 21.0 225 26 13 7.3 4.0
14500 -3.7 25.3 205 21 11 8.5 4.7 | -5.1 22.8 220 25 13 7.3 4.0
14000 -2.4 27.7 200 21 11 8.6 4.7 | -4.0 24.8 220 23 12 7.0 3.9
13500 -1.2 29.8 195 21 11 8.7 4.8 | -3.0 26.6 220 20 11 7.1 3.9
13000 0.1 32.2 195 20 11 8.7 4.8 | -2.1 28.2 225 18 9 6.3 3.5
12500 1.4 34.5 195 20 10 9.1 5.0 | -1.2 29.8 225 16 8 6.5 3.6
12000 2.5 36.5 190 20 10 5.8 3.2 | -0.3 31.5 230 14 7 5.1 2.8
11500 3.3 37.9 185 19 10 6.7 3.7 | 0.4 32.7 235 12 6 5.3 2.9
11000 3.8 38.8 180 17 9 1.1 0.6 | 1.1 34.0 245 11 6 4.7 2.6
10500 3.8 38.8 170 15 7 1.7 0.9 | 1.8 35.2 255 11 6 5.5 3.0
10250 3.9 39.0 160 14 7 0.9 0.5 | 2.2 36.0 260 11 6 1.6 0.9
10000 4.0 39.2 155 12 6 3.0 1.6 | 2.2 36.0 265 11 6 3.2 1.8
9750 4.3 39.7 145 10 5 5.3 2.9 | 2.7 36.9 270 11 6 8.2 4.5
9500 4.7 40.5 130 8 4 4.9 2.7 | 3.3 37.9 275 11 5 6.9 3.8
9250 5.0 41.0 105 7 4 4.0 2.2 | 3.7 38.7 280 11 5 5.7 3.1
9000 5.4 41.7 095 7 4 6.6 3.6 | 4.1 39.4 285 10 5 5.3 2.9
8750 6.0 42.8 080 7 4 9.8 5.4 | 4.5 40.1 290 10 5 7.3 4.0
8500 6.7 44.1 070 8 4 9.4 5.1 | 5.1 41.2 300 10 5 6.8 3.8
8250 7.4 45.3 065 8 4 9.8 5.4 | 5.5 41.9 305 10 5 5.1 2.8
8000 8.2 46.8 060 9 4 9.9 5.4 | 5.8 42.4 315 9 5 4.4 2.4
7750 8.9 48.0 055 9 5 9.9 5.4 | 6.1 43.0 320 9 5 4.4 2.4
7500 9.7 49.5 050 9 5 9.7 5.3 | 6.4 43.5 325 10 5 3.3 1.8
7250 10.4 50.7 045 9 5 9.6 5.2 | 6.6 43.9 335 10 5 2.4 1.3
7000 11.1 52.0 045 9 5 9.6 5.2 | 6.7 44.1 340 10 5 2.7 1.5
6750 11.8 53.2 040 9 5 10.2 5.6 | 6.9 44.4 345 11 6 2.1 1.1
6500 12.6 54.7 040 9 5 10.8 5.9 | 7.0 44.6 345 12 6 1.5 0.8
6250 13.4 56.1 040 9 5 11.3 6.2 | 7.1 44.8 345 12 6 1.4 0.8
6000 14.2 57.6 035 10 5 9.8 5.4 | 7.2 45.0 340 13 7 2.1 1.2
5750 15.0 59.0 035 10 5 14.1 7.7 | 7.5 45.5 340 13 7 8.8 4.8
5500 16.6 61.9 035 9 5 27.2 14.9 | 8.5 47.3 340 11 6 17.3 9.5
________________________________________________________________________________
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.
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