Huntsville State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Huntsville State Park clear sky chart from 2005-11-05 to 2018-01-12.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
48%
15924
25%
48323
17%
15875
56%
15875
31%
28658

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
31%
956
24%
2472
9%
951
41%
951
28%
1626
January16th to endNight
28%
960
28%
2496
9%
960
39%
960
29%
1622
February1st to 15thNight
28%
785
24%
2186
9%
779
38%
779
26%
1407
February16th to endNight
22%
536
26%
1798
10%
536
37%
536
22%
1104
March1st to 15thNight
28%
540
25%
1980
12%
540
42%
540
22%
1211
March16th to endNight
33%
576
22%
2112
14%
576
45%
576
24%
1231
April1st to 15thNight
34%
539
22%
1941
14%
539
47%
539
25%
1128
April16th to endNight
34%
540
23%
1800
16%
540
47%
540
27%
1081
May1st to 15thNight
33%
539
20%
1679
14%
539
43%
539
27%
1018
May16th to endNight
55%
563
26%
1684
23%
561
64%
561
37%
968
June1st to 15thNight
74%
540
20%
1620
21%
540
78%
540
47%
832
June16th to endNight
75%
540
20%
1620
21%
540
78%
540
39%
926
July1st to 15thNight
77%
510
19%
1530
22%
510
79%
510
40%
853
July16th to endNight
82%
564
19%
1594
23%
531
83%
531
38%
901
August1st to 15thNight
88%
539
29%
1610
33%
536
88%
536
55%
759
August16th to endNight
76%
573
17%
1914
20%
573
77%
573
28%
1161
September1st to 15thNight
73%
540
16%
1980
19%
540
75%
540
28%
1139
September16th to endNight
70%
537
28%
1980
32%
537
72%
537
31%
1092
October1st to 15thNight
70%
658
32%
2098
28%
658
72%
658
43%
1052
October16th to endNight
56%
768
37%
2304
24%
768
65%
768
45%
1185
November1st to 15thNight
48%
760
27%
2280
18%
760
55%
760
33%
1333
November16th to endNight
44%
846
33%
2406
19%
846
53%
846
35%
1403
December1st to 15thNight
33%
975
25%
2535
12%
975
42%
975
25%
1726
December16th to endNight
31%
1040
21%
2704
9%
1040
38%
1040
23%
1900

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
12%5%25%5%35%5%5%7%40%
49002
Night
10%5%2432345%7%49%
48527
TransparencyDay
42%5%10%18%16%6%
48702
Night
34%5%12%20%18%9%
48332
SeeingDay
10%5%18%27%28%9%
5789
Night
13%6%25%32%18%2
15925

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
17%6%24323346%43%
1710
16th to endDay
18%6%24423345%45%
1728
February1st to 15thDay
17%6%35%313335%45%
1678
16th to endDay
18%7%25%423345%42%
1676
March1st to 15thDay
21%7%35%423345%38%
1980
16th to endDay
15%6%45%423236%43%
2110
April1st to 15thDay
15%6%25%5%33446%40%
2006
16th to endDay
12%5%35%5%35%5%5%8%38%
2160
May1st to 15thDay
11%7%37%6%36%6%5%7%34%
2268
16th to endDay
9%435%7%46%6%6%10%34%
2430
June1st to 15thDay
5%425%7%5%7%7%7%9%37%
2340
16th to endDay
7%426%7%5%9%7%7%8%31%
2340
July1st to 15thDay
9%436%7%46%7%7%9%33%
2340
16th to endDay
6%436%8%6%7%7%8%11%29%
2466
August1st to 15thDay
5%2235%36%6%8%9%45%
2340
16th to endDay
8%5%27%5%5%6%7%7%8%34%
2285
September1st to 15thDay
8%436%6%47%6%6%6%38%
1980
16th to endDay
7%426%6%45%5%6%6%43%
1980
October1st to 15thDay
9%413434445%52%
1848
16th to endDay
10%31221333462%
1920
November1st to 15thDay
9%5%25%5%25%5%5%7%45%
1908
16th to endDay
12%6%1442334452%
1882
December1st to 15thDay
18%8%35%325%435%39%
1755
16th to endDay
20%9%26%424345%35%
1872
January1st to 15thNight
17%6%24313336%46%
2472
16th to endNight
19%5%24323236%47%
2496
February1st to 15thNight
15%7%34323245%46%
2183
16th to endNight
16%6%25%323335%46%
1798
March1st to 15thNight
18%6%24413347%43%
1980
16th to endNight
10%6%44424446%48%
2112
April1st to 15thNight
9%5%25%43445%8%46%
1941
16th to endNight
12%5%15%43335%9%45%
1800
May1st to 15thNight
9%5%25%42446%8%44%
1679
16th to endNight
442432446%11%50%
1683
June1st to 15thNight
32321346%12%57%
1620
16th to endNight
32134247%9%13%48%
1620
July1st to 15thNight
43243135%7%12%49%
1620
16th to endNight
3213336%5%8%13%47%
1702
August1st to 15thNight
21221245%12%63%
1620
16th to endNight
6%3146%35%6%7%10%43%
1914
September1st to 15thNight
6%415%5%246%6%8%47%
1980
16th to endNight
7%41342446%8%50%
1980
October1st to 15thNight
5%313323446%61%
2098
16th to endNight
9%31321223465%
2304
November1st to 15thNight
9%5%23324346%52%
2280
16th to endNight
12%424323335%54%
2406
December1st to 15thNight
18%7%24324336%42%
2535
16th to endNight
18%9%35%42333440%
2704

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
42%35%14%22%10%
1711
16th to endDay
41%35%14%21%13%
1728
February1st to 15thDay
42%25%17%18%12%
1679
16th to endDay
45%36%14%19%10%
1676
March1st to 15thDay
49%37%12%21%6%
1980
16th to endDay
43%38%16%22%6%
2112
April1st to 15thDay
45%5%417%17%9%
2006
16th to endDay
43%5%8%17%18%7%
2160
May1st to 15thDay
47%6%9%15%13%6%
2268
16th to endDay
42%8%10%19%16%2
2434
June1st to 15thDay
38%8%13%21%16%1
2340
16th to endDay
46%9%13%19%10%1
2340
July1st to 15thDay
43%8%16%20%10%
2201
16th to endDay
45%10%16%20%7%
2311
August1st to 15thDay
31%7%18%28%12%
2326
16th to endDay
45%9%17%19%6%2
2285
September1st to 15thDay
42%7%13%18%12%5%
1980
16th to endDay
39%5%11%18%17%7%
1980
October1st to 15thDay
33%49%20%16%15%
1848
16th to endDay
26%25%13%32%18%
1920
November1st to 15thDay
36%5%10%19%19%8%
1908
16th to endDay
35%35%14%25%14%
1882
December1st to 15thDay
48%38%15%15%8%
1755
16th to endDay
51%36%16%13%7%
1872
January1st to 15thNight
40%26%16%20%13%
2472
16th to endNight
41%25%14%22%14%
2496
February1st to 15thNight
40%35%15%20%14%
2193
16th to endNight
41%36%15%17%15%
1798
March1st to 15thNight
42%38%14%20%10%
1980
16th to endNight
38%411%15%21%8%
2112
April1st to 15thNight
36%5%9%18%18%12%
1941
16th to endNight
37%5%11%19%18%9%
1800
May1st to 15thNight
37%5%13%19%15%8%
1680
16th to endNight
28%7%15%29%15%3
1685
June1st to 15thNight
19%7%18%30%21%1
1620
16th to endNight
24%10%20%30%13%1
1620
July1st to 15thNight
25%8%28%27%10%
1530
16th to endNight
24%10%28%29%6%
1594
August1st to 15thNight
14%5%24%40%13%
1610
16th to endNight
34%8%24%24%5%2
1914
September1st to 15thNight
32%8%22%18%11%5%
1980
16th to endNight
30%6%13%20%19%8%
1980
October1st to 15thNight
23%311%27%19%14%
2098
16th to endNight
24%25%15%30%21%
2304
November1st to 15thNight
33%411%20%20%8%
2280
16th to endNight
32%37%15%25%16%
2406
December1st to 15thNight
45%37%18%16%9%
2535
16th to endNight
47%36%15%17%9%
2704

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
24%11%32%19%8%3
123
16th to endDay
16%19%41%15%6%
96
February1st to 15thDay
8%23%37%25%4
90
16th to endDay
13%16%46%19%3
81
March1st to 15thDay
25%22%33%12%5%1
90
16th to endDay
11%13%33%30%11%
96
April1st to 15thDay
13%13%32%23%17%
125
16th to endDay
16%9%31%27%13%1
270
May1st to 15thDay
14%12%37%23%10%1
405
16th to endDay
10%6%31%31%17%2
517
June1st to 15thDay
5%111%37%35%7%
495
16th to endDay
8%11%32%35%11%
495
July1st to 15thDay
7%8%32%38%13%
475
16th to endDay
45%23%47%19%
515
August1st to 15thDay
5%324%50%16%
493
16th to endDay
16%5%18%36%23%
325
September1st to 15thDay
119%25%40%21%
135
16th to endDay
45%25%42%20%
135
October1st to 15thDay
2111%37%34%13%
135
16th to endDay
17%8%16%25%25%6%
144
November1st to 15thDay
13%324%40%14%2
135
16th to endDay
10%11%30%31%11%4
135
December1st to 15thDay
27%7%24%22%8%8%
135
16th to endDay
32%15%31%17%2
144
January1st to 15thNight
21%13%28%27%8%
956
16th to endNight
21%12%34%25%5%
960
February1st to 15thNight
20%13%33%27%4
785
16th to endNight
20%12%41%22%3
536
March1st to 15thNight
22%8%38%25%4
540
16th to endNight
12%11%40%27%9%
576
April1st to 15thNight
10%11%40%30%7%
539
16th to endNight
16%9%37%27%9%
540
May1st to 15thNight
13%6%42%28%7%
540
16th to endNight
6%231%39%18%1
563
June1st to 15thNight
413%48%30%2
540
16th to endNight
313%45%32%4
540
July1st to 15thNight
5%8%47%33%6%
510
16th to endNight
45%44%42%4
564
August1st to 15thNight
3247%40%5%
539
16th to endNight
8%5%36%41%6%
573
September1st to 15thNight
8%7%32%42%7%
540
16th to endNight
8%10%31%42%6%
537
October1st to 15thNight
7%215%39%28%6%
658
16th to endNight
10%426%32%23%2
768
November1st to 15thNight
11%5%30%32%19%1
760
16th to endNight
15%8%29%29%16%
846
December1st to 15thNight
22%9%29%26%11%
975
16th to endNight
25%10%28%28%6%
1040
Page generated at 2018-01-12 21:01:29. Version ac04

Copyright 2018 A. Danko


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