I have been calculating instability while storm chasing for years. While the models do fairly well at predicting upper-level
        temperatures, they tend to do poorly at low-levels where theta-e changes rapidly in time and space. While 500mb temps change
        very slowly(except with upper level cold pools), low level temperatures and dewpoints change rapidly and vary tremendously
        on the mesoscale. So, a good way to stay abreast on the amount of instability in your target area is to actually measure the low
        level temperature and dewpoint, and then look at morning upper air data, model initializations and 6-12 hr fcsts valid at 18Z to
        approximate the 500mb temp, and then just find the lifted index on a skew-t log P diagram. Yes, I know its easier just to use
        some objective analysis scheme provided on the internet, but how accurate are these? Certainly not very accurate in the data
        sparse areas of the western high plains. The models tend to fail miserably on the western high plains and dramatically underestimate
        instability. It is fun to monitor the cool side of an outflow boundary, warm front, or any area where moisture is pooling, since
        surface observations often are non-existent. Of course you have to know the elevation. I have provided elevation maps to help
        in this process. Of course, this is easy for those with GPS. On this page I will provide tables for 500mb temps between -6 and
        -20C. Some of the values listed below are inaccurate and need to be tweaked, so use with caution.

    500mb temp = -6C
    assume sea level pressure 1005mb
    note T/TD in degrees F
 

	-5	-7	-9	-11	-13
Laramie   7240	77/52   73/53   69/56   65/58	81/55   78/57   74/59   69/60	83/57   79/58   75/60   71/62	X	X
Cheyenne  6140	80/55  76/57    72/59   69/60	84/58   80/60   76/62   72/63	86/60   81/61   77/63   73/65		X
Akron   4700	84/58   80/60   77/61   73/63	88/61   84/63   80/65   76/67	90/63   84/64   81/66   77/68
Goodland  3700	86/61   82/63   79/64   74/66	9/64    86/66   82/68    78/70	91/65   86/67   83/68   77/71
Gage   2220	89/63  85/65    81/67   77/69	93/66   89/68   85/70   81/72	94/68   89/70   86/72   80/74
Wichita   1340	93/66  88/68   84/70   81/71	95/69   91/71   87/73   83/74	97/70   92/72   88/74   82/76
Dallas   500	94/68   89/70   85/72   81/73	96/71   92/72   88/74   84/76	98/72   93/74   89/76   84/77

    500mb temp = -8C
    assume sea level pressure 1005mb
    note T/TD in degrees F
 

	-5	-7	-9	-11	-13
Laramie  7240	75/49    71/51  67/54   63/55	77/52   73/53   69/56   65/58	81/55   78/57   74/59   71/62	83/57   79/58   75/60   71/62	X
Cheyenne 6140	78/53    74/54  70/56   66/58	80/55   76/57   72/59   69/60	84/58   80/60   76/62   72/63	86/60   81/61   77/63   73/65
Akron  4700	82/56    78/57   75/59  70/61	84/58   80/60   77/61   73/63	88/61   84/63   80/65   76/67	90/63   84/64   81/66   77/68
Goodland  3700	84/59    80/60  76/62   72/64	86/61   82/63   79/64   74/66	89/64   86/66   82/68   78/70	91/65   86/67   83/68   77/71
Gage  2220	87/61    83/63  79/65   75/67	89/63   85/65   81/67   77/69	93/66   89/68   85/70   81/72	94/68   89/70   86/72   80/74
Wichita 1340	91/64   86/66   82/68   78/69	93/66  88/68   84/70   80/71	95/69   91/71   87/73   83/74	97/70   92/72   88/74   82/76
Dallas  500	92/66   87/68   83/70   78/72	94/68   89/70   85/72   81/73	96/71   92/72   88/74   84/76	98/72   93/74   89/76   84/77

    500mb temp = -10C
    assume sea level pressure 1005mb
    note T/TD in degrees F
 

	-5	-7	-9	-11	-13
Laramie   7240	73/46  69/49   65/50   61/53	75/48   71/51   67/53   63/55	78/51   73/53   69/55   65/57	80/53   76/55  72/57    68/59	83/57   79/58   75/60   71/62
Cheyenne   6140	76/49  72/52   68/54   64/56	78/52   74/54   70/56   66/58	80/54   76/56   72/58   68/60	82/56   78/58  74/60    71/62	86/60   81/61   77/63   73/65
Akron   4700	80/53  76/55   72/57   68/59	82/55   78/57   75/59   71/61	84/57   80/59   76/61   72/63	86/59   82/61   78/63   74/65	90/63   84/64   81/66   77/68
Goodland  3700	82/56  78/58   74/60   70/62	84/58   80/60   76/62   72/64	86/60   82/62   78/64   74/66	88/62   84/64  80/66    76/68	91/65   86/67   83/68   77/71
Gage  2220	85/59  81/61   77/63   73/65	87/61   83/63   79/65   75/67	89/63  85/65    81/67   77/69	91/64   87/66  83/68    79/70	94/68   89/70   86/72   80/74
Wichita  1340	88/62  84/64   80/66   76/68	90/64   86/66   82/68   78/70	92/66  88/68    84/70   80/72	93/67  89/69   85/71    82/73	97/70   92/72   88/74   82/76
Dallas  500	89/64  85/66   82/68   77/70	91/66   87/68   83/70   78/72	93/68   89/70   85/72   81/73	94/69  90/71   86/73    83/75	98/72   93/74   89/76   84/77

    500mb temp = -12C
    assume sea level pressure 1005mb
    note T/TD in degrees F
 

	-5	-7	-9	-11	-13
Laramie 7240	69/42   65/45   61/48   59/51	73/46  69/49   65/50   61/53	75/48   71/51   67/53   63/55	78/51   73/53   69/55   65/57	80/53   76/55   72/57    68/59
Cheyenne 6140	74/47   70/49   66/52   62/54	76/49  72/52   68/54   64/56	78/52   74/54   70/55   66/58	80/54   76/56   72/58  68/60	82/56   78/58   76/60    71/62
Akron 4700	78/51   74/53   70/55   66/57	80/53  76/55   72/57   68/59	82/55   78/57   75/59   71/61	84/57   80/59   76/61   72/63	86/59   82/61   78/63   74/65
Goodland 3700	80/54   76/56   72/58   68/60	82/56  78/58   74/60   70/62	84/58   80/60   76/62   72/64	86/60   82/62   78/64   74/66	88/62   84/64   80/66    76/68
Gage 2220	83/57   79/59   75/61  71/63	85/60  81/62   77/64   73/66	87/61   83/63   79/65   75/67	89/63   85/65   81/67   77/69	91/64   87/66   83/68    79/70
Wichita  1340	86/60   82/62  78/64    74/66	88/62  84/64   80/66   76/68	90/64   86/66   82/68   78/70	92/66  88/68   84/70   80/72	93/67   89/69   85/71    82/73
Dallas  500	87/62   83/64  79/66    75/68	89/64  85/66   82/68   77/70	91/66   87/68   83/70   78/72	93/68   89/70   85/72   81/73	94/69   90/71   86/73    83/75

    500mb temp = -16C
    assume sea level pressure 1005mb
    note T/Td in degrees F
 

	-5	-7	-9	-11	-13
Laramie  7240	63/37   59/39   56/42   52/45	65/39   61/42   59/45   55/47	68/41   65/43   61/45   57/48	73/47  69/49   65/51   61/53	75/49   71/51   67/53   63/55
Cheyenne  6140	68/42   64/44   60/46   56/48	70/44   66/46   62/48   58/50	72/46   68/48   64/50   60/52	76/50  72/52   68/54   64/56	78/52   74/54   70/55   66/58
Akron  4700	74/47   70/49   66/47   62/49	76/49   72/51   68/53   64/55	77/50   72/51   68/53   64/55	80/53  76/55   72/57   68/59	82/55   78/57   75/59   71/61
Goodland  3700	76/49   72/51   68/53   64/54	78/52   74/54   70/56   66/58	80/53   76/54   72/55   67/58	82/56  78/58   74/60   70/62	84/58   80/60   76/62   72/64
Gage  2220	79/51   75/53  71/55    67/56	82/55   78/57   74/59   70/61	83/56   79/57   75/59   71/62	85/60  81/62   77/64   73/66	87/61   83/63   79/65   75/67
Wichita  1340	82/54  78/56   74/58    70/60	84/58   80/60   76/62   72/64	86/59   82/62   78/63   74/64	88/62  84/64   80/66   76/68	90/64   86/66   82/68   78/70
Dallas  500	83/57  79/59   75/61    71/63	85/60   81/62   77/64   73/66	87/61   83/64   79/65   75/67	89/64  85/66   82/68   77/70	91/66   87/68   83/70   78/72

    500mb temp = -20C
    assume sea level pressure 1005mb
    note T/Td in degrees F
 

	-5	-7	-9	-11	-13
Laramie   7240	56/32	59/34   56/37   53/40   50/42	62/37   59/39  56/42   52/45	65/39   61/42   57/45   55/47	68/41   65/43   61/45   57/48
Cheyenne   6140			68/42   64/44  60/46   56/48	70/44   66/46   62/48   58/50	72/46   68/48   64/50   60/52
Akron  4700		69/42   66/44   62/48   58/51	72/45   70/49  66/47   62/49	74/47   70/49   66/51   62/53	77/50   72/51   68/53   64/55
Goodland   3700			76/49  72/51   68/53   64/54	78/52   74/54   70/56   66/58	80/53   76/54   72/55   67/58
Gage   2220			79/51  75/53   71/55   67/56	82/55   78/57   74/59   70/61	83/56   79/57   75/59   71/62
Wichita  1340			81/54  77/56   74/58   70/60	83/57   80/60   76/62   72/64	86/60   82/63   78/63   74/64
Dallas   500	75/51	78/54   76/57   72/59   69/60	82/57  79/59   75/61   71/63	84/59   81/62   77/64   73/66	87/61   83/64   79/65   75/67