640
UXUS97 KPUB 201305
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO, COLORADO
0605 MST WEDNESDAY, NOVEMBER 20, 2024
THIS FORECAST IS FOR VILLA GROVE, CO FOR WEDNESDAY, NOVEMBER 20, 2024:
IF THE TRIGGER TEMPERATURE OF 43.2 F/6.2 C IS REACHED...THEN
THERMAL SOARING INDEX....................... FAIR
MAXIMUM RATE OF LIFT........................ 381 FT/MIN (1.9 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 12629 FT MSL (3629 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 41.0 F/5.5 C
TIME OF TRIGGER TEMPERATURE.................... NONE
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................. 11708 FT MSL (2708 FT AGL)
THERMAL SOARING OUTLOOK FOR THURSDAY 11/21..... GOOD
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 06:51:08 / 16:47:36 MST
TOTAL POSSIBLE SUNSHINE........... 9 HR 56 MIN 28 SEC (596 MIN 28 SEC)
ALTITUDE OF SUN AT 11:49:22 MST... 31.75 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 11/20/2024 AT 0500 MST
FREEZING LEVEL.................. ENTIRE AIRMASS BELOW 32 F / 0 C
CONVECTIVE CONDENSATION LEVEL... 24896 FT MSL (15896 FT AGL)
LIFTED CONDENSATION LEVEL....... 19557 FT MSL (10557 FT AGL)
LIFTED INDEX.................... +11.4
K INDEX......................... -9.2
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 -62.1 -79.8 280 62 32 -2.8 -1.5 M M M M M
45000 -66.2 -87.2 285 82 42 -1.0 -0.5 M M M M M
40000 -63.3 -81.9 305 93 48 1.9 1.1 M M M M M
38000 -60.3 -76.5 305 92 47 7.1 3.9 M M M M M
36000 -55.5 -67.9 300 84 43 7.1 3.9 M M M M M
34000 -51.0 -59.8 295 78 40 8.1 4.4 M M M M M
32000 -46.1 -51.0 295 72 37 8.1 4.4 M M M M M
30000 -41.3 -42.3 290 67 34 8.1 4.4 23.0 73.3 14.1 M M
29000 -38.8 -37.8 290 65 34 8.1 4.4 22.3 72.1 13.7 M M
28000 -36.4 -33.5 290 64 33 8.1 4.4 21.7 71.1 13.4 M M
27000 -34.0 -29.2 290 63 32 8.3 4.5 21.2 70.1 13.1 M M
26000 -31.5 -24.7 290 61 31 8.2 4.5 20.5 68.9 12.7 M M
25000 -29.0 -20.2 290 60 31 8.3 4.5 20.0 68.0 12.5 M M
24000 -26.6 -15.9 290 58 30 8.3 4.5 19.5 67.2 12.2 M M
23000 -24.1 -11.4 295 54 28 8.3 4.5 18.9 66.1 11.8 M M
22000 -21.6 -6.9 295 50 26 8.3 4.5 18.4 65.2 11.5 M M
21000 -19.2 -2.6 295 47 24 8.0 4.4 17.9 64.3 11.2 M M
20000 -16.8 1.8 300 49 25 8.0 4.4 17.3 63.1 10.8 M M
19500 -15.6 3.9 300 50 26 8.0 4.4 17.0 62.6 10.6 M M
19000 -14.4 6.1 300 52 27 8.0 4.4 16.7 62.1 10.4 M M
18500 -13.2 8.2 300 52 27 8.3 4.5 16.5 61.7 10.2 M M
18000 -11.3 11.7 300 51 26 8.4 4.6 16.1 61.0 10.0 M M
17500 -10.1 13.8 300 50 26 6.7 3.7 15.8 60.5 9.8 M M
17000 -9.2 15.4 300 50 26 6.2 3.4 15.2 59.4 9.3 M M
16500 -8.3 17.1 295 50 26 5.7 3.1 14.7 58.4 8.8 M M
16000 -7.6 18.3 295 50 26 4.4 2.4 13.8 56.9 8.0 M M
15500 -6.9 19.6 295 50 26 4.8 2.6 13.0 55.4 7.3 M M
15000 -6.5 20.3 290 50 26 1.6 0.9 11.9 53.5 6.3 M M
14500 -6.2 20.8 290 50 26 2.0 1.1 10.7 51.2 5.1 M M
14000 -6.1 21.0 290 51 26 0.1 0.0 9.3 48.7 3.8 M M
13500 -6.0 21.2 285 50 26 0.1 0.1 7.8 46.0 2.4 M M
13000 -6.0 21.2 285 50 26 -0.2 -0.1 6.3 43.4 1.0 M M
12500 -6.1 21.0 285 49 25 -1.1 -0.6 4.6 40.3 -0.6 377 1.9
12000 -6.2 20.8 285 47 24 -0.8 -0.4 2.9 37.3 -2.2 367 1.9
11750 -6.3 20.7 285 46 24 -2.1 -1.2 2.1 35.8 -3.0 361 1.8
11500 -6.5 20.3 285 45 23 -3.3 -1.8 1.1 34.0 -3.9 360 1.8
11250 -6.7 19.9 285 44 23 -2.8 -1.6 0.1 32.2 -4.9 359 1.8
11000 -6.9 19.6 280 42 22 -1.4 -0.8 -0.8 30.5 -5.8 357 1.8
10750 -7.0 19.4 280 39 20 -1.5 -0.8 -1.6 29.0 -6.6 352 1.8
10500 -7.1 19.2 280 37 19 -2.8 -1.6 -2.6 27.4 -7.6 350 1.8
10250 -7.4 18.7 280 35 18 -5.0 -2.7 -3.6 25.5 -8.6 351 1.8
10000 -7.9 17.8 275 31 16 -8.6 -4.7 -4.9 23.3 -9.9 359 1.8
9750 -8.7 16.3 270 27 14 -9.5 -5.2 -6.3 20.7 -11.4 373 1.9
9500 -9.4 15.1 265 23 12 -10.5 -5.8 -7.8 18.0 -12.9 388 2.0
9250 -10.3 13.5 255 19 10 -13.3 -7.3 -9.4 15.1 -14.5 408 2.1
9000 -11.2 11.8 240 10 5 -7.6 -4.2 -11.0 12.1 -16.2 428 2.2
8750 M M M M M M M M M M M M
8500 M M M M M M M M M M M M
8250 M M M M M M M M M M M M
8000 M M M M M M M M M M M M
* * * * * * NUMERICAL WEATHER PREDICTION MODEL FORECAST DATA VALID * * * * * *
11/20/2024 AT 0800 MST | 11/20/2024 AT 1100 MST
|
CAPE... 0.0 LI... +1.2 | CAPE... 0.0 LI... +2.3
CINH... 0.0 K INDEX... -3.0 | CINH... 0.0 K INDEX... -0.9
|
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 -63.5 -82.3 285 61 31 -3.8 -2.1 | -63.5 -82.3 280 52 27 -3.7 -2.0
45000 -69.2 -92.6 290 83 43 -0.1 -0.1 | -68.7 -91.7 285 82 42 5.2 2.8
40000 -62.6 -80.7 300 88 45 4.2 2.3 | -62.5 -80.5 295 87 45 4.2 2.3
38000 -58.7 -73.7 300 86 44 7.4 4.1 | -58.5 -73.3 295 85 44 7.7 4.2
36000 -54.3 -65.7 300 83 43 7.4 4.1 | -53.9 -65.0 290 80 41 7.7 4.2
34000 -49.8 -57.6 295 78 40 7.6 4.2 | -49.2 -56.6 290 75 39 7.7 4.2
32000 -45.3 -49.5 295 71 36 7.6 4.2 | -44.0 -47.2 290 69 36 7.7 4.2
30000 -40.6 -41.1 295 64 33 8.2 4.5 | -39.3 -38.7 290 64 33 8.3 4.5
29000 -37.6 -35.7 290 61 32 8.2 4.5 | -36.8 -34.2 290 60 31 8.3 4.5
28000 -35.1 -31.2 290 59 30 8.2 4.5 | -34.3 -29.7 290 57 29 8.3 4.5
27000 -32.7 -26.9 290 57 29 7.8 4.3 | -31.9 -25.4 290 54 28 7.9 4.3
26000 -30.4 -22.7 290 53 28 7.8 4.3 | -29.5 -21.1 290 50 26 7.9 4.3
25000 -28.1 -18.6 290 50 26 7.8 4.3 | -27.2 -17.0 290 47 24 7.9 4.3
24000 -25.7 -14.3 295 48 25 7.7 4.2 | -24.9 -12.8 290 44 22 6.8 3.7
23000 -23.4 -10.1 295 46 23 7.7 4.2 | -22.8 -9.0 285 40 21 6.9 3.8
22000 -21.2 -6.2 290 43 22 7.7 4.2 | -20.8 -5.4 285 36 19 6.9 3.8
21000 -18.9 -2.0 290 41 21 7.1 3.9 | -18.7 -1.7 285 33 17 6.9 3.8
20000 -16.8 1.8 290 39 20 7.2 3.9 | -16.7 1.9 285 31 16 6.9 3.8
19500 -15.7 3.7 295 38 20 7.2 3.9 | -15.6 3.9 290 30 15 6.9 3.8
19000 -14.6 5.7 295 37 19 7.0 3.8 | -14.6 5.7 290 29 15 6.9 3.8
18500 -13.5 7.7 295 35 18 8.7 4.8 | -13.6 7.5 290 28 15 7.0 3.9
18000 -12.2 10.0 295 34 17 8.6 4.7 | -12.5 9.5 290 29 15 7.1 3.9
17500 -10.9 12.4 295 32 16 8.5 4.7 | -11.5 11.3 295 29 15 7.2 4.0
17000 -9.6 14.7 295 30 15 8.3 4.5 | -10.3 13.5 295 29 15 7.5 4.1
16500 -8.4 16.9 295 27 14 8.4 4.6 | -9.2 15.4 295 28 15 7.5 4.1
16000 -7.2 19.0 290 28 15 7.3 4.0 | -7.6 18.3 295 29 15 7.0 3.8
15500 -6.1 21.0 290 32 16 7.5 4.1 | -6.6 20.1 295 30 16 6.6 3.6
15000 -5.1 22.8 290 35 18 5.1 2.8 | -5.7 21.7 295 32 17 5.2 2.9
14500 -4.1 24.6 290 39 20 5.2 2.9 | -4.9 23.2 295 35 18 4.6 2.5
14000 -3.7 25.3 290 41 21 0.3 0.1 | -4.5 23.9 295 38 20 2.4 1.3
13500 -3.6 25.5 285 43 22 0.9 0.5 | -4.1 24.6 295 41 21 2.6 1.4
13000 -3.6 25.5 285 45 23 -1.9 -1.0 | -3.9 25.0 290 43 22 -0.6 -0.3
12500 -4.0 24.8 285 45 23 -2.6 -1.4 | -4.1 24.6 290 43 22 -1.4 -0.8
12000 -4.5 23.9 285 45 23 -3.4 -1.9 | -4.4 24.1 290 43 22 -2.0 -1.1
11750 -4.8 23.4 285 44 22 -4.7 -2.6 | -4.5 23.9 290 42 22 -3.0 -1.7
11500 -5.2 22.6 285 42 22 -5.8 -3.2 | -4.8 23.4 290 41 21 -4.0 -2.2
11250 -5.6 21.9 285 40 21 -4.8 -2.6 | -5.0 23.0 290 40 21 -2.8 -1.5
11000 -5.8 21.6 280 39 20 -3.0 -1.6 | -5.2 22.6 290 36 19 -2.0 -1.1
10750 -6.0 21.2 280 37 19 -3.7 -2.1 | -5.3 22.5 285 31 16 0.1 0.0
10500 -6.4 20.5 280 36 18 -5.9 -3.2 | -5.2 22.6 280 27 14 2.1 1.2
10250 -6.9 19.6 280 34 18 -8.0 -4.4 | -4.9 23.2 275 23 12 6.5 3.6
10000 -7.6 18.3 275 30 16 -9.6 -5.3 | -4.2 24.4 275 20 11 10.6 5.8
9750 -8.3 17.1 270 26 13 -9.8 -5.4 | -3.5 25.7 270 18 10 9.6 5.3
9500 -9.0 15.8 260 22 11 -8.5 -4.7 | -2.7 27.1 265 16 8 10.7 5.9
9250 -9.4 15.1 250 17 9 -1.7 -0.9 | -1.7 28.9 265 14 7 16.3 9.0
9000 -9.1 15.6 235 10 5 13.7 7.5 | -0.0 32.0 260 11 6 31.8 17.5
8750 M M M M M M M | M M M M M M M
8500 M M M M M M M | M M M M M M M
8250 M M M M M M M | M M M M M M M
8000 M M M M M M M | M M M M M M M
11/20/2024 AT 1400 MST | 11/20/2024 AT 1700 MST
|
CAPE... 0.0 LI... +4.0 | CAPE... 0.0 LI... +3.7
CINH... 0.0 K INDEX... -3.4 | CINH... 0.0 K INDEX... -1.4
|
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 -65.4 -85.7 280 60 31 -3.4 -1.8 | -66.1 -87.0 290 63 32 -3.1 -1.7
45000 -69.8 -93.6 290 84 43 5.9 3.2 | -69.7 -93.5 285 82 42 6.2 3.4
40000 -62.0 -79.6 290 91 47 5.2 2.9 | -60.7 -77.3 290 90 47 5.9 3.3
38000 -57.8 -72.0 290 86 44 7.5 4.1 | -56.6 -69.9 295 84 43 7.1 3.9
36000 -53.3 -63.9 290 80 41 7.5 4.1 | -52.3 -62.1 295 76 39 7.1 3.9
34000 -48.6 -55.5 290 73 37 8.2 4.5 | -47.8 -54.0 295 70 36 7.9 4.4
32000 -43.7 -46.7 295 65 33 8.2 4.5 | -42.5 -44.5 300 67 34 7.9 4.4
30000 -38.4 -37.1 295 59 30 7.6 4.2 | -37.7 -35.9 300 63 32 7.9 4.3
29000 -36.1 -33.0 290 57 30 7.6 4.2 | -35.4 -31.7 300 61 31 7.9 4.3
28000 -33.8 -28.8 290 56 29 7.6 4.2 | -33.0 -27.4 300 58 30 7.9 4.3
27000 -31.4 -24.5 290 52 27 8.4 4.6 | -30.5 -22.9 300 55 28 8.6 4.7
26000 -28.9 -20.0 290 45 23 8.5 4.6 | -27.9 -18.2 305 51 26 8.6 4.7
25000 -26.4 -15.5 290 39 20 8.5 4.6 | -25.4 -13.7 305 47 24 8.6 4.7
24000 -23.9 -11.0 290 34 18 7.4 4.1 | -22.9 -9.2 305 45 23 7.4 4.1
23000 -21.7 -7.1 290 37 19 7.6 4.1 | -20.6 -5.1 305 49 25 7.5 4.1
22000 -19.4 -2.9 290 40 20 7.5 4.1 | -18.4 -1.1 300 52 27 7.5 4.1
21000 -17.3 0.9 290 41 21 6.5 3.6 | -16.4 2.5 300 53 27 5.3 2.9
20000 -15.3 4.5 290 40 21 6.6 3.6 | -14.8 5.4 300 51 26 5.4 3.0
19500 -14.3 6.3 295 40 20 6.6 3.6 | -14.0 6.8 300 49 25 5.4 3.0
19000 -13.4 7.9 295 39 20 6.6 3.6 | -13.2 8.2 300 48 25 5.4 2.9
18500 -12.4 9.7 295 39 20 6.2 3.4 | -12.4 9.7 300 47 24 6.1 3.4
18000 -11.5 11.3 295 38 20 6.2 3.4 | -11.5 11.3 300 46 24 6.1 3.3
17500 -10.5 13.1 295 38 20 5.8 3.2 | -10.6 12.9 300 46 24 5.7 3.1
17000 -9.8 14.4 295 39 20 5.3 2.9 | -9.8 14.4 300 46 23 5.5 3.0
16500 -9.0 15.8 295 39 20 5.2 2.9 | -9.0 15.8 300 45 23 5.5 3.0
16000 -8.3 17.1 300 40 21 4.3 2.4 | -7.7 18.1 300 45 23 5.6 3.1
15500 -7.3 18.9 300 41 21 4.4 2.4 | -6.9 19.6 305 45 23 5.5 3.0
15000 -6.7 19.9 300 41 21 4.4 2.4 | -6.1 21.0 305 45 23 5.2 2.8
14500 -6.1 21.0 300 42 21 4.4 2.4 | -5.4 22.3 305 44 23 5.0 2.7
14000 -5.5 22.1 300 42 22 3.3 1.8 | -4.7 23.5 305 43 22 4.4 2.4
13500 -5.0 23.0 300 42 21 3.5 1.9 | -4.1 24.6 305 42 22 4.6 2.6
13000 -4.6 23.7 300 40 21 1.3 0.7 | -3.6 25.5 305 40 21 2.0 1.1
12500 -4.5 23.9 300 38 20 0.7 0.4 | -3.3 26.1 305 37 19 2.2 1.2
12000 -4.4 24.1 295 36 18 -0.7 -0.4 | -3.0 26.6 300 35 18 0.9 0.5
11750 -4.5 23.9 295 33 17 -0.8 -0.4 | -3.0 26.6 300 33 17 -1.2 -0.7
11500 -4.6 23.7 290 30 16 -2.1 -1.2 | -3.1 26.4 295 32 16 -2.9 -1.6
11250 -4.6 23.7 285 28 14 2.3 1.2 | -3.3 26.1 295 31 16 -0.6 -0.3
11000 -4.2 24.4 280 25 13 7.4 4.1 | -3.2 26.2 290 29 15 1.4 0.8
10750 -3.6 25.5 275 22 11 8.2 4.5 | -3.1 26.4 285 27 14 1.8 1.0
10500 -3.0 26.6 275 20 10 9.8 5.4 | -2.9 26.8 280 24 12 2.5 1.4
10250 -2.2 28.0 270 18 9 9.8 5.4 | -2.7 27.1 270 22 11 3.9 2.1
10000 -1.5 29.3 270 17 9 9.7 5.3 | -2.3 27.9 265 20 10 4.8 2.6
9750 -0.8 30.6 265 16 8 9.6 5.3 | -2.0 28.4 260 18 9 5.3 2.9
9500 -0.0 32.0 265 15 8 11.1 6.1 | -1.6 29.1 255 16 8 4.2 2.3
9250 1.0 33.8 265 13 7 16.2 8.9 | -1.6 29.1 250 13 6 -5.5 -3.0
9000 2.4 36.3 260 11 6 22.0 12.0 | -2.7 27.1 235 8 4 -25.1 -13.8
8750 M M M M M M M | M M M M M M M
8500 M M M M M M M | M M M M M M M
8250 M M M M M M M | M M M M M M M
8000 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). 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 VILLA GROVE, COLORADO AT:
NORTH LATITUDE: 38 DEG 16 MIN 03 SEC
WEST LONGITUDE: 105 DEG 53 MIN 37 SEC
ELEVATION: 7986 FEET (2434 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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page