Thomaston
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Thomaston clear sky chart from 2005-11-05 to 2017-09-24.

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
49%
15537
24%
47024
16%
15493
58%
15493
29%
28587

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
27%
720
24%
2327
10%
716
45%
716
21%
1420
January16th to endNight
28%
768
24%
2418
11%
768
42%
768
22%
1519
February1st to 15thNight
31%
704
27%
2109
11%
700
47%
700
26%
1293
February16th to endNight
27%
631
26%
1893
9%
631
43%
631
26%
1148
March1st to 15thNight
31%
720
26%
2061
12%
720
44%
720
28%
1261
March16th to endNight
40%
768
24%
2112
13%
768
49%
768
31%
1286
April1st to 15thNight
43%
644
26%
1902
17%
644
52%
644
33%
1093
April16th to endNight
50%
540
28%
1722
21%
540
59%
540
34%
942
May1st to 15thNight
53%
539
24%
1620
15%
539
61%
539
33%
956
May16th to endNight
61%
561
22%
1682
16%
561
65%
561
33%
1004
June1st to 15thNight
68%
540
17%
1620
15%
540
69%
540
30%
1010
June16th to endNight
76%
540
18%
1620
16%
540
77%
540
34%
984
July1st to 15thNight
76%
510
12%
1530
11%
510
76%
510
29%
981
July16th to endNight
74%
564
15%
1595
12%
531
76%
531
28%
1036
August1st to 15thNight
73%
539
17%
1675
18%
536
74%
536
29%
1075
August16th to endNight
64%
573
17%
1910
19%
573
65%
573
22%
1264
September1st to 15thNight
66%
711
20%
1971
18%
711
67%
711
29%
1285
September16th to endNight
59%
693
24%
1914
18%
693
63%
693
29%
1237
October1st to 15thNight
55%
660
32%
1815
24%
660
63%
660
38%
1063
October16th to endNight
53%
704
35%
2106
27%
704
64%
704
38%
1144
November1st to 15thNight
51%
700
31%
2246
25%
700
63%
700
35%
1202
November16th to endNight
39%
720
28%
2340
18%
720
54%
720
29%
1324
December1st to 15thNight
37%
720
24%
2340
17%
720
48%
720
24%
1423
December16th to endNight
33%
768
21%
2496
14%
768
44%
768
20%
1637

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%6%7%40%
47896
Night
11%42442445%8%46%
47226
TransparencyDay
40%6%11%18%17%5%
47597
Night
35%5%10%19%19%8%
47029
SeeingDay
15%6%18%23%22%12%
5420
Night
14%7%21%28%22%4
15540

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
16%6%24324335%46%
1611
16th to endDay
17%5%34424436%43%
1803
February1st to 15thDay
13%5%25%42445%6%44%
1750
16th to endDay
15%6%24323446%44%
1580
March1st to 15thDay
14%6%246%22446%44%
1897
16th to endDay
14%5%25%424446%44%
2111
April1st to 15thDay
12%5%245%23446%47%
2055
16th to endDay
9%42442435%7%51%
2238
May1st to 15thDay
10%425%5%345%5%7%44%
2331
16th to endDay
8%3246%36%5%6%9%42%
2431
June1st to 15thDay
9%5%26%8%47%6%7%9%31%
2340
16th to endDay
43146%5%8%7%9%10%37%
2340
July1st to 15thDay
10%5%36%7%48%8%9%11%26%
2340
16th to endDay
6%5%35%7%49%9%9%12%24%
2465
August1st to 15thDay
8%5%26%8%47%8%8%10%26%
2271
16th to endDay
14%6%25%8%5%6%6%7%8%27%
2289
September1st to 15thDay
14%5%25%6%36%6%7%7%33%
1980
16th to endDay
15%6%25%5%3445%7%38%
1905
October1st to 15thDay
14%413323335%52%
1815
16th to endDay
11%31332333458%
1766
November1st to 15thDay
11%423324345%54%
1610
16th to endDay
14%324424236%50%
1620
December1st to 15thDay
16%5%2442345%6%44%
1620
16th to endDay
23%8%35%324335%36%
1728
January1st to 15thNight
16%6%24314345%46%
2327
16th to endNight
18%5%24423435%44%
2418
February1st to 15thNight
15%433424346%48%
2103
16th to endNight
14%5%23424446%47%
1893
March1st to 15thNight
12%424424336%50%
2061
16th to endNight
11%5%2431335%7%49%
2112
April1st to 15thNight
11%41341345%8%50%
1902
16th to endNight
8%3144245%47%53%
1722
May1st to 15thNight
7%324435%5%5%7%50%
1619
16th to endNight
6%4245%35%5%6%8%46%
1682
June1st to 15thNight
6%425%6%345%7%11%40%
1620
16th to endNight
3315%436%8%7%15%39%
1620
July1st to 15thNight
6%4145%47%8%7%12%36%
1620
16th to endNight
6%3245%38%8%8%13%34%
1703
August1st to 15thNight
5%4246%46%6%7%12%37%
1686
16th to endNight
11%5%26%6%36%5%6%11%34%
1910
September1st to 15thNight
9%425%5%35%5%6%9%40%
1971
16th to endNight
10%6%26%5%3446%7%42%
1914
October1st to 15thNight
12%413323345%54%
1815
16th to endNight
10%31242234459%
2106
November1st to 15thNight
10%413323345%57%
2246
16th to endNight
13%424324246%52%
2340
December1st to 15thNight
14%6%25%324345%46%
2340
16th to endNight
20%6%245%23446%38%
2496

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
41%36%15%26%6%
1612
16th to endDay
40%5%5%15%23%8%
1803
February1st to 15thDay
40%35%19%23%7%
1752
16th to endDay
40%35%17%24%7%
1580
March1st to 15thDay
40%38%18%20%8%
1897
16th to endDay
39%5%9%20%20%4
2112
April1st to 15thDay
37%38%21%20%8%
2055
16th to endDay
32%410%20%24%7%
2238
May1st to 15thDay
37%5%11%19%21%4
2331
16th to endDay
37%6%13%25%14%3
2435
June1st to 15thDay
43%8%14%21%9%1
2340
16th to endDay
35%9%17%20%14%2
2340
July1st to 15thDay
44%11%21%14%6%2
2201
16th to endDay
44%10%18%18%7%
2310
August1st to 15thDay
46%9%17%18%7%
2258
16th to endDay
50%8%14%15%9%
2289
September1st to 15thDay
43%9%12%15%14%4
1980
16th to endDay
43%49%21%16%4
1905
October1st to 15thDay
34%39%20%23%8%
1815
16th to endDay
29%35%16%30%15%
1766
November1st to 15thDay
32%3417%26%15%
1610
16th to endDay
35%37%17%24%11%
1620
December1st to 15thDay
38%410%18%19%8%
1620
16th to endDay
50%27%17%14%8%
1728
January1st to 15thNight
39%35%18%25%7%
2327
16th to endNight
42%35%14%23%10%
2418
February1st to 15thNight
38%3320%21%12%
2112
16th to endNight
37%36%17%23%10%
1893
March1st to 15thNight
36%48%19%21%9%
2061
16th to endNight
33%49%21%23%7%
2112
April1st to 15thNight
31%48%24%21%10%
1902
16th to endNight
30%410%23%22%9%
1722
May1st to 15thNight
31%7%12%19%23%5%
1620
16th to endNight
32%7%14%26%14%5%
1684
June1st to 15thNight
34%9%17%26%12%
1620
16th to endNight
30%9%21%21%14%2
1620
July1st to 15thNight
34%11%24%18%7%3
1530
16th to endNight
33%12%23%19%8%1
1595
August1st to 15thNight
35%9%20%22%9%1
1675
16th to endNight
41%9%17%16%13%1
1910
September1st to 15thNight
36%8%15%19%16%3
1971
16th to endNight
39%6%11%19%16%6%
1914
October1st to 15thNight
31%49%21%20%12%
1815
16th to endNight
27%3416%30%16%
2106
November1st to 15thNight
28%36%16%29%15%
2246
16th to endNight
34%26%16%25%13%
2340
December1st to 15thNight
39%38%18%21%8%
2340
16th to endNight
46%37%17%17%6%
2496

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
23%18%35%10%7%4
90
16th to endDay
20%21%44%6%6%
96
February1st to 15thDay
21%20%37%17%3
90
16th to endDay
27%11%48%13%
81
March1st to 15thDay
22%15%29%18%11%1
187
16th to endDay
15%10%31%27%14%
288
April1st to 15thDay
22%12%24%20%18%2
270
16th to endDay
11%7%30%26%18%6%
270
May1st to 15thDay
14%10%27%19%14%13%
288
16th to endDay
14%314%27%26%13%
331
June1st to 15thDay
10%214%22%27%21%
315
16th to endDay
7%210%27%26%24%
315
July1st to 15thDay
9%7%23%31%26%
305
16th to endDay
6%15%22%35%27%
326
August1st to 15thDay
13%25%27%32%19%
313
16th to endDay
15%27%27%29%18%
332
September1st to 15thDay
18%39%20%32%16%
315
16th to endDay
19%211%33%23%10%
287
October1st to 15thDay
20%316%28%23%7%
255
16th to endDay
13%7%18%27%25%7%
272
November1st to 15thDay
27%11%21%23%14%1
118
16th to endDay
16%7%35%25%12%2
90
December1st to 15thDay
23%15%33%16%11%
90
16th to endDay
41%10%27%16%4
96
January1st to 15thNight
22%17%27%24%8%
720
16th to endNight
21%14%31%27%5%
768
February1st to 15thNight
19%12%30%29%7%
704
16th to endNight
17%18%34%25%4
631
March1st to 15thNight
15%14%35%27%8%
720
16th to endNight
17%11%26%28%15%
768
April1st to 15thNight
14%9%29%27%17%
644
16th to endNight
10%8%26%34%19%1
540
May1st to 15thNight
8%5%28%28%25%3
540
16th to endNight
10%118%32%31%6%
563
June1st to 15thNight
8%19%35%33%11%
540
16th to endNight
417%30%42%12%
540
July1st to 15thNight
8%1426%43%15%
510
16th to endNight
8%15%23%48%12%
564
August1st to 15thNight
8%5%24%45%15%
539
16th to endNight
14%16%25%38%13%
573
September1st to 15thNight
11%19%25%39%11%
711
16th to endNight
13%212%36%31%3
693
October1st to 15thNight
15%321%26%28%4
660
16th to endNight
12%8%22%29%24%2
704
November1st to 15thNight
13%8%22%32%21%2
700
16th to endNight
14%11%28%28%15%1
720
December1st to 15thNight
19%10%28%26%12%1
720
16th to endNight
24%11%26%28%8%1
768
Page generated at 2017-09-25 09:02:29. Version ac04

Copyright 2017 A. Danko


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