520
UXUS97 KPUB 101224
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO, COLORADO
0624 MDT FRIDAY, MAY 10, 2024
THIS FORECAST IS FOR VILLA GROVE, CO FOR FRIDAY, MAY 10, 2024:
IF THE TRIGGER TEMPERATURE OF 38.6 F/3.7 C IS REACHED...THEN
THERMAL SOARING INDEX....................... POOR
MAXIMUM RATE OF LIFT........................ 142 FT/MIN (0.7 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 14965 FT MSL (6001 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 44.0 F/7.1 C
TIME OF TRIGGER TEMPERATURE.................... 1145 MDT
TIME OF OVERDEVELOPMENT........................ 1200 MDT
MIDDLE/HIGH CLOUDS DURING SOARING WINDOW....... BROKEN/OVERCAST OPAQUE MIDDLE
SURFACE WINDS DURING SOARING WINDOW............ 20 MPH OR LESS
HEIGHT OF THE -3 THERMAL INDEX................. 12893 FT MSL (3929 FT AGL)
THERMAL SOARING OUTLOOK FOR SATURDAY 05/11..... FAIR
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 05:56:18 / 20:03:38 MDT
TOTAL POSSIBLE SUNSHINE........... 14 HR 7 MIN 21 SEC (847 MIN 21 SEC)
ALTITUDE OF SUN AT 12:59:58 MDT... 69.63 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 05/10/2024 AT 0600 MDT
FREEZING LEVEL.................. ENTIRE AIRMASS BELOW 32 F / 0 C
CONVECTIVE CONDENSATION LEVEL... 12498 FT MSL (3534 FT AGL)
LIFTED CONDENSATION LEVEL....... 13990 FT MSL (5026 FT AGL)
LIFTED INDEX.................... +1.4
K INDEX......................... +17.0
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 -55.2 -67.4 260 22 11 1.9 1.0 M M M M M
45000 -52.5 -62.5 250 21 11 0.9 0.5 M M M M M
40000 -50.9 -59.6 250 39 20 1.0 0.6 M M M M M
38000 -50.3 -58.5 250 48 25 1.0 0.6 M M M M M
36000 -49.7 -57.5 250 58 30 1.0 0.6 M M M M M
34000 -48.5 -55.3 250 65 34 4.5 2.5 M M M M M
32000 -45.7 -50.3 250 62 32 4.6 2.5 M M M M M
30000 -42.9 -45.2 245 55 28 4.8 2.6 22.3 72.1 12.2 M M
29000 -41.5 -42.7 240 45 23 4.8 2.7 20.3 68.5 10.7 M M
28000 -40.1 -40.2 235 35 18 4.9 2.7 18.4 65.2 9.4 M M
27000 -38.0 -36.4 220 26 13 8.5 4.7 16.6 61.8 8.0 M M
26000 -35.6 -32.1 220 24 13 8.3 4.6 16.0 60.7 7.6 M M
25000 -33.1 -27.6 225 22 12 8.3 4.6 15.5 59.8 7.3 M M
24000 -30.6 -23.1 220 21 11 8.2 4.5 15.0 59.1 7.0 M M
23000 -28.2 -18.8 215 24 12 8.1 4.5 14.4 57.9 6.5 M M
22000 -25.8 -14.4 210 27 14 8.1 4.5 13.8 56.9 6.1 M M
21000 -23.4 -10.1 205 30 15 7.8 4.3 13.3 55.9 5.6 M M
20000 -21.1 -6.0 200 32 17 7.9 4.3 12.6 54.7 5.1 M M
19500 -19.9 -3.8 195 33 17 7.9 4.3 12.3 54.1 4.8 M M
19000 -18.8 -1.8 190 35 18 7.9 4.4 12.0 53.6 4.6 M M
18500 -17.6 0.3 190 35 18 7.3 4.0 11.7 53.1 4.3 M M
18000 -16.6 2.1 185 35 18 7.3 4.0 11.3 52.3 3.9 M M
17500 -15.5 4.1 180 35 18 6.8 3.7 10.9 51.6 3.5 M M
17000 -14.6 5.7 175 33 17 5.9 3.2 10.3 50.5 3.0 M M
16500 -13.8 7.2 170 32 16 5.9 3.3 9.6 49.3 2.4 M M
16000 -13.0 8.6 165 31 16 4.6 2.5 8.9 48.0 1.7 M M
15500 -12.3 9.9 155 29 15 4.8 2.6 8.1 46.6 1.0 M M
15000 -11.6 11.1 150 28 15 4.8 2.6 7.3 45.1 0.2 M M
14500 -10.9 12.4 140 27 14 4.8 2.6 6.5 43.7 -0.5 516 2.6
14000 -10.2 13.6 135 26 13 5.5 3.0 5.8 42.4 -1.3 480 2.4
13500 -8.9 16.0 125 24 12 6.2 3.4 4.8 40.7 -2.2 420 2.1
13000 -8.2 17.2 120 23 12 4.3 2.4 4.0 39.3 -3.0 384 2.0
12500 -7.4 18.7 115 22 12 5.7 3.1 3.4 38.1 -3.6 345 1.8
12000 -6.5 20.3 105 22 11 6.0 3.3 2.8 37.1 -4.3 304 1.5
11750 -6.1 21.0 105 22 11 6.1 3.4 2.5 36.5 -4.6 284 1.4
11500 -5.6 21.9 100 22 11 6.5 3.6 2.3 36.1 -4.9 263 1.3
11250 -5.2 22.6 095 22 11 5.5 3.0 2.0 35.6 -5.2 242 1.2
11000 -4.9 23.2 095 22 11 4.4 2.4 1.6 34.9 -5.6 225 1.1
10750 -4.5 23.9 090 22 11 4.8 2.6 1.2 34.2 -6.0 207 1.1
10500 -4.2 24.4 090 21 11 5.2 2.9 0.8 33.5 -6.4 189 1.0
10250 -3.8 25.2 090 21 11 5.1 2.8 0.5 32.9 -6.7 171 0.9
10000 -3.4 25.9 085 19 10 4.9 2.7 0.1 32.2 -7.1 153 0.8
9750 -3.1 26.4 085 17 9 5.0 2.8 -0.2 31.6 -7.5 134 0.7
9500 -2.7 27.1 080 15 8 6.9 3.8 -0.5 31.1 -7.8 115 0.6
9250 -2.1 28.2 075 11 6 9.7 5.3 -0.6 30.9 -8.0 89 0.5
9000 -1.5 29.3 065 7 3 4.0 2.2 -0.7 30.7 -8.2 65 0.3
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 * * * * * *
05/10/2024 AT 0900 MDT | 05/10/2024 AT 1200 MDT
|
CAPE... +7.1 LI... +0.1 | CAPE... +80.4 LI... +0.7
CINH... -0.3 K INDEX... +17.3 | CINH... -0.3 K INDEX... +8.1
|
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 -55.3 -67.5 255 27 14 1.4 0.8 | -55.0 -67.0 255 29 15 0.9 0.5
45000 -53.2 -63.8 260 28 15 1.2 0.6 | -53.6 -64.5 250 33 17 0.4 0.2
40000 -51.4 -60.5 250 45 23 1.2 0.6 | -52.9 -63.2 245 50 26 0.5 0.3
38000 -50.8 -59.4 245 50 26 1.0 0.5 | -52.0 -61.6 245 52 27 1.8 1.0
36000 -50.2 -58.4 245 53 27 1.0 0.5 | -50.9 -59.6 240 53 27 1.8 1.0
34000 -48.6 -55.5 245 55 29 6.9 3.8 | -48.9 -56.0 240 55 28 6.7 3.7
32000 -44.4 -47.9 245 58 30 7.0 3.8 | -44.8 -48.6 245 55 28 6.8 3.7
30000 -40.6 -41.1 245 56 29 4.4 2.4 | -40.8 -41.4 245 55 28 6.2 3.4
29000 -39.3 -38.7 245 49 25 4.3 2.3 | -39.0 -38.2 245 54 28 6.2 3.4
28000 -38.1 -36.6 240 43 22 4.3 2.4 | -36.7 -34.1 240 52 27 6.2 3.4
27000 -36.3 -33.3 235 35 18 6.9 3.8 | -34.8 -30.6 240 49 25 6.3 3.5
26000 -34.3 -29.7 235 28 14 6.6 3.6 | -32.9 -27.2 240 41 21 6.3 3.5
25000 -32.3 -26.1 230 21 11 6.7 3.6 | -31.0 -23.8 235 33 17 6.3 3.5
24000 -30.3 -22.5 220 15 8 7.6 4.2 | -29.1 -20.4 225 26 13 7.0 3.8
23000 -28.0 -18.4 220 17 9 7.9 4.3 | -26.9 -16.4 215 20 10 7.1 3.9
22000 -25.7 -14.3 220 20 10 7.9 4.3 | -24.8 -12.6 200 15 8 7.1 3.9
21000 -23.4 -10.1 220 22 11 6.5 3.6 | -22.8 -9.0 185 13 7 6.3 3.4
20000 -21.5 -6.7 215 24 12 6.7 3.7 | -20.9 -5.6 190 13 7 6.4 3.5
19500 -20.5 -4.9 210 25 13 6.7 3.7 | -20.0 -4.0 190 13 7 6.4 3.5
19000 -19.5 -3.1 210 26 14 6.7 3.7 | -19.0 -2.2 190 13 7 6.5 3.5
18500 -18.5 -1.3 205 28 14 6.9 3.8 | -18.1 -0.6 195 14 7 5.8 3.2
18000 -17.5 0.5 200 29 15 6.9 3.8 | -17.3 0.9 195 15 8 5.8 3.2
17500 -16.5 2.3 195 30 15 7.2 3.9 | -16.4 2.5 200 16 8 6.2 3.4
17000 -15.4 4.3 195 31 16 7.5 4.1 | -15.5 4.1 200 17 9 6.6 3.6
16500 -14.3 6.3 195 31 16 7.5 4.1 | -14.5 5.9 200 19 10 6.7 3.7
16000 -13.2 8.2 190 32 17 7.6 4.2 | -13.5 7.7 205 20 10 7.4 4.0
15500 -12.1 10.2 190 33 17 7.7 4.2 | -12.5 9.5 205 21 11 7.4 4.1
15000 -11.0 12.2 185 33 17 6.7 3.7 | -11.5 11.3 205 22 11 6.6 3.6
14500 -10.1 13.8 180 32 17 6.6 3.6 | -10.5 13.1 205 22 11 6.7 3.6
14000 -9.1 15.6 175 32 16 6.0 3.3 | -9.1 15.6 200 22 11 6.5 3.6
13500 -8.0 17.6 165 29 15 5.4 2.9 | -8.1 17.4 200 22 12 6.5 3.6
13000 -7.3 18.9 155 28 14 3.7 2.0 | -7.2 19.0 195 21 11 6.6 3.6
12500 -6.7 19.9 145 26 13 3.9 2.1 | -6.2 20.8 185 18 9 7.2 3.9
12000 -6.1 21.0 135 24 12 4.5 2.5 | -5.4 22.3 170 16 8 4.7 2.6
11750 -5.8 21.6 130 23 12 3.8 2.1 | -5.0 23.0 160 15 8 5.8 3.2
11500 -5.5 22.1 125 22 11 3.5 1.9 | -4.5 23.9 150 14 7 6.1 3.3
11250 -5.3 22.5 120 21 11 3.7 2.0 | -4.1 24.6 140 14 7 5.6 3.1
11000 -5.0 23.0 110 20 10 3.5 1.9 | -3.7 25.3 130 13 7 5.0 2.7
10750 -4.7 23.5 105 19 10 4.1 2.2 | -3.3 26.1 120 13 7 6.0 3.3
10500 -4.4 24.1 100 18 9 4.9 2.7 | -2.9 26.8 110 13 6 7.3 4.0
10250 -4.0 24.8 095 17 9 6.0 3.3 | -2.3 27.9 100 12 6 8.7 4.8
10000 -3.6 25.5 090 16 8 6.6 3.6 | -1.6 29.1 095 12 6 9.7 5.3
9750 -3.1 26.4 085 15 8 6.4 3.5 | -1.0 30.2 090 12 6 9.1 5.0
9500 -2.6 27.3 085 13 7 9.0 5.0 | -0.3 31.5 085 11 6 11.4 6.3
9250 -1.8 28.8 080 10 5 13.6 7.4 | 0.8 33.4 080 10 5 17.8 9.8
9000 -0.9 30.4 070 7 4 7.8 4.3 | 2.1 35.8 080 8 4 16.9 9.2
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
05/10/2024 AT 1500 MDT | 05/10/2024 AT 1800 MDT
|
CAPE... +93.1 LI... -0.4 | CAPE... +94.2 LI... +0.2
CINH... -6.4 K INDEX... +14.4 | CINH... 0.0 K INDEX... +18.1
|
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 -55.0 -67.0 260 32 17 1.0 0.5 | -55.2 -67.4 260 29 15 1.4 0.8
45000 -53.6 -64.5 245 43 22 0.2 0.1 | -53.3 -63.9 250 42 22 -0.1 -0.0
40000 -53.2 -63.8 245 52 27 0.3 0.2 | -53.3 -63.9 250 51 26 0.1 0.0
38000 -52.2 -62.0 245 55 28 2.4 1.3 | -52.2 -62.0 245 55 28 2.4 1.3
36000 -50.8 -59.4 245 57 29 2.4 1.3 | -50.8 -59.4 245 59 30 2.4 1.3
34000 -48.7 -55.7 245 58 30 5.6 3.1 | -48.8 -55.8 245 61 31 5.1 2.8
32000 -45.3 -49.5 245 56 29 5.7 3.1 | -45.8 -50.4 250 58 30 5.1 2.8
30000 -41.6 -42.9 245 54 28 7.2 4.0 | -42.3 -44.1 250 54 28 7.3 4.0
29000 -39.5 -39.1 245 52 27 7.3 4.0 | -40.1 -40.2 250 50 26 7.3 4.0
28000 -36.7 -34.1 250 51 26 7.3 4.0 | -37.4 -35.3 250 47 24 7.3 4.0
27000 -34.6 -30.3 250 49 25 7.4 4.1 | -35.2 -31.4 250 43 22 7.5 4.1
26000 -32.3 -26.1 245 47 24 7.4 4.1 | -33.0 -27.4 250 40 21 7.5 4.1
25000 -30.1 -22.2 245 44 23 7.4 4.1 | -30.7 -23.3 250 37 19 7.5 4.1
24000 -28.0 -18.4 245 41 21 6.3 3.4 | -28.5 -19.3 250 34 18 6.8 3.7
23000 -26.1 -15.0 240 35 18 6.2 3.4 | -26.5 -15.7 245 31 16 6.8 3.7
22000 -24.3 -11.7 240 28 14 6.2 3.4 | -24.5 -12.1 235 29 15 6.9 3.8
21000 -22.4 -8.3 235 24 12 6.0 3.3 | -22.4 -8.3 230 28 14 8.1 4.4
20000 -20.7 -5.3 230 24 12 6.1 3.4 | -20.0 -4.0 225 27 14 8.1 4.4
19500 -19.8 -3.6 230 24 12 6.2 3.4 | -18.9 -2.0 225 27 14 8.1 4.4
19000 -18.9 -2.0 225 24 12 6.3 3.5 | -17.7 0.1 225 27 14 8.2 4.5
18500 -17.9 -0.2 225 24 12 7.5 4.1 | -16.6 2.1 220 27 14 6.9 3.8
18000 -16.8 1.8 225 23 12 7.5 4.1 | -15.5 4.1 225 26 14 7.0 3.9
17500 -15.7 3.7 225 21 11 7.7 4.2 | -14.5 5.9 225 26 13 7.1 3.9
17000 -14.6 5.7 225 22 11 7.9 4.3 | -13.5 7.7 225 25 13 7.2 4.0
16500 -13.4 7.9 225 22 11 7.9 4.3 | -12.4 9.7 230 24 12 7.2 4.0
16000 -12.3 9.9 225 22 11 7.1 3.9 | -11.4 11.5 230 23 12 6.5 3.6
15500 -11.3 11.7 225 21 11 7.2 3.9 | -10.4 13.3 230 22 11 6.5 3.6
15000 -10.2 13.6 225 21 11 7.4 4.0 | -9.4 15.1 235 20 10 7.3 4.0
14500 -8.6 16.5 225 19 10 6.6 3.6 | -7.8 18.0 230 17 9 6.6 3.6
14000 -7.7 18.1 220 18 9 6.9 3.8 | -6.9 19.6 225 15 8 7.0 3.8
13500 -6.7 19.9 220 17 9 6.7 3.7 | -5.9 21.4 215 14 7 6.9 3.8
13000 -5.7 21.7 215 15 8 6.7 3.7 | -4.9 23.2 210 11 6 6.8 3.7
12500 -4.8 23.4 205 13 6 6.9 3.8 | -3.9 25.0 195 9 5 8.0 4.4
12000 -4.0 24.8 190 9 5 3.8 2.1 | -3.1 26.4 175 8 4 3.2 1.8
11750 -3.7 25.3 175 8 4 4.8 2.6 | -2.8 27.0 160 8 4 5.4 2.9
11500 -3.4 25.9 155 7 4 4.8 2.6 | -2.3 27.9 145 8 4 6.0 3.3
11250 -3.0 26.6 135 8 4 5.1 2.8 | -1.9 28.6 130 9 4 5.2 2.9
11000 -2.7 27.1 125 9 4 5.0 2.7 | -1.6 29.1 125 9 5 4.6 2.5
10750 -2.3 27.9 115 9 5 6.2 3.4 | -1.3 29.7 125 10 5 4.8 2.6
10500 -1.8 28.8 110 10 5 8.0 4.4 | -1.0 30.2 120 10 5 4.0 2.2
10250 -1.2 29.8 100 10 5 8.8 4.9 | -0.6 30.9 115 10 5 7.0 3.8
10000 -0.5 31.1 095 9 5 9.6 5.3 | -0.0 32.0 115 9 5 9.7 5.3
9750 0.2 32.4 090 9 5 9.1 5.0 | 0.6 33.1 110 8 4 9.0 4.9
9500 0.9 33.6 085 9 4 11.0 6.1 | 1.3 34.3 110 8 4 10.2 5.6
9250 1.9 35.4 080 8 4 17.7 9.7 | 2.1 35.8 105 6 3 12.3 6.7
9000 3.4 38.1 080 7 3 22.4 12.3 | 3.0 37.4 100 6 3 12.9 7.1
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