Hemlock Crossings Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hemlock Crossings Park clear sky chart from 2005-11-05 to 2017-03-24.

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
37%
15459
13%
45261
10%
15417
40%
15417
17%
33455

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
13%
900
5%
2506
2%
895
16%
895
6%
2230
January16th to endNight
17%
960
3%
2688
2%
960
18%
960
6%
2409
February1st to 15thNight
18%
739
6%
2210
2%
739
21%
739
9%
1856
February16th to endNight
23%
631
10%
1893
5%
631
27%
631
11%
1523
March1st to 15thNight
34%
720
14%
2151
10%
720
37%
720
18%
1559
March16th to endNight
38%
682
18%
1977
13%
682
44%
682
23%
1358
April1st to 15thNight
35%
494
14%
1647
11%
494
40%
494
18%
1143
April16th to endNight
43%
495
20%
1521
13%
495
50%
495
24%
1010
May1st to 15thNight
43%
495
16%
1485
9%
495
48%
495
20%
1035
May16th to endNight
54%
514
14%
1400
11%
513
57%
513
28%
938
June1st to 15thNight
56%
495
15%
1320
11%
495
59%
495
31%
864
June16th to endNight
60%
495
13%
1320
9%
495
62%
495
30%
861
July1st to 15thNight
68%
465
17%
1240
14%
465
69%
465
40%
735
July16th to endNight
70%
522
18%
1305
16%
489
70%
489
38%
803
August1st to 15thNight
69%
494
24%
1443
20%
491
72%
491
39%
821
August16th to endNight
66%
525
20%
1695
18%
525
70%
525
31%
992
September1st to 15thNight
62%
544
24%
1699
24%
544
65%
544
32%
993
September16th to endNight
57%
657
21%
1815
16%
657
60%
657
32%
1153
October1st to 15thNight
48%
660
22%
1846
17%
660
52%
660
27%
1235
October16th to endNight
24%
704
11%
2288
7%
704
31%
704
14%
1702
November1st to 15thNight
34%
700
17%
2276
15%
700
38%
700
16%
1624
November16th to endNight
21%
720
8%
2340
6%
720
24%
720
8%
1934
December1st to 15thNight
12%
888
3%
2508
1%
888
13%
888
5%
2267
December16th to endNight
11%
960
4%
2688
1%
960
14%
960
6%
2410

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
14%9%46%5%3445%7%35%
45677
Night
16%11%5%7%5%24345%32%
45429
Cloud CoverDay
14%9%46%5%3445%7%35%
45686
Night
16%11%5%7%5%34345%32%
45434
TransparencyDay
48%6%12%20%10%1
45363
Night
54%5%10%17%10%1
45261
SeeingDay
16%5%22%30%18%6%
5214
Night
20%7%25%29%14%1
15463

By Month

Percentage Cloud Cover NE (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
18%15%9%12%9%5%6%43311%
1432
16th to endDay
14%19%10%15%11%35%32210%
1536
February1st to 15thDay
12%15%8%13%11%4433416%
1648
16th to endDay
15%13%7%10%6%5%5%5%5%6%19%
1580
March1st to 15thDay
14%11%48%6%345%5%7%27%
1799
16th to endDay
15%9%45%42335%7%37%
2100
April1st to 15thDay
20%10%35%423347%33%
1971
16th to endDay
16%6%25%33445%7%39%
2109
May1st to 15thDay
19%5%25%42445%8%36%
2136
16th to endDay
10%325%4345%5%8%47%
2360
June1st to 15thDay
11%415%435%45%8%45%
2310
16th to endDay
8%41443445%9%47%
2310
July1st to 15thDay
5%413325%5%6%9%52%
2310
16th to endDay
8%31342446%9%49%
2459
August1st to 15thDay
9%42442345%9%48%
2178
16th to endDay
11%325%42346%8%47%
2153
September1st to 15thDay
13%42443445%8%44%
1920
16th to endDay
11%5%35%435%36%8%41%
1815
October1st to 15thDay
18%6%25%6%24445%38%
1780
16th to endDay
24%7%37%6%43447%25%
1584
November1st to 15thDay
16%11%36%435%345%34%
1582
16th to endDay
22%20%5%8%5%2333418%
1620
December1st to 15thDay
19%24%12%12%6%2212311%
1449
16th to endDay
21%22%10%10%5%2433311%
1536
January1st to 15thNight
20%16%9%11%10%3332314%
2506
16th to endNight
14%16%12%12%11%3443411%
2688
February1st to 15thNight
13%19%7%14%8%4422318%
2208
16th to endNight
17%16%5%10%6%35%335%22%
1893
March1st to 15thNight
16%10%47%5%23446%33%
2138
16th to endNight
15%7%45%5%3435%5%39%
1977
April1st to 15thNight
19%9%45%43445%6%34%
1647
16th to endNight
18%6%25%424445%40%
1521
May1st to 15thNight
18%6%26%5%345%5%6%34%
1485
16th to endNight
11%5%36%5%2446%7%42%
1398
June1st to 15thNight
10%5%25%5%35%45%8%43%
1320
16th to endNight
7%435%6%35%5%6%8%42%
1320
July1st to 15thNight
7%314435%36%8%52%
1320
16th to endNight
6%3134145%6%8%52%
1401
August1st to 15thNight
6%4244235%5%8%53%
1452
16th to endNight
11%42442335%6%51%
1695
September1st to 15thNight
12%324433345%51%
1699
16th to endNight
10%5%245%34346%49%
1815
October1st to 15thNight
22%6%24313345%42%
1846
16th to endNight
27%9%26%42334431%
2288
November1st to 15thNight
18%12%35%423346%34%
2276
16th to endNight
22%20%6%9%5%13345%18%
2340
December1st to 15thNight
22%23%10%11%5%2222311%
2508
16th to endNight
22%22%9%11%5%2323411%
2688

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%15%8%12%10%5%6%44311%
1432
16th to endDay
14%19%11%14%11%45%22210%
1536
February1st to 15thDay
12%15%8%13%12%45%335%16%
1648
16th to endDay
15%13%7%9%7%5%45%5%6%19%
1580
March1st to 15thDay
15%11%37%6%35%5%5%8%26%
1809
16th to endDay
15%9%45%42345%7%37%
2099
April1st to 15thDay
20%10%45%413347%33%
1971
16th to endDay
16%6%25%4235%5%7%38%
2109
May1st to 15thDay
19%5%25%42445%8%36%
2136
16th to endDay
10%425%43445%8%47%
2360
June1st to 15thDay
11%4245%35%45%8%44%
2310
16th to endDay
9%414435%45%9%47%
2310
July1st to 15thDay
6%413335%5%6%9%51%
2310
16th to endDay
8%31342446%9%49%
2459
August1st to 15thDay
9%325%42445%10%47%
2178
16th to endDay
12%42442346%8%46%
2153
September1st to 15thDay
13%5%2343445%8%45%
1920
16th to endDay
11%5%34435%36%8%41%
1815
October1st to 15thDay
18%6%25%5%34446%38%
1780
16th to endDay
24%8%27%6%3435%7%25%
1584
November1st to 15thDay
16%11%36%425%35%5%34%
1582
16th to endDay
22%19%5%8%5%2433419%
1620
December1st to 15thDay
18%24%12%12%6%2312411%
1449
16th to endDay
21%22%10%9%7%2433311%
1536
January1st to 15thNight
20%15%9%12%10%3432314%
2506
16th to endNight
14%15%12%12%11%4433412%
2688
February1st to 15thNight
13%17%8%13%8%4423319%
2201
16th to endNight
17%15%6%9%6%34435%22%
1893
March1st to 15thNight
17%10%46%5%3445%6%33%
2151
16th to endNight
15%7%35%5%34346%39%
1977
April1st to 15thNight
19%9%35%5%2445%6%33%
1647
16th to endNight
18%6%25%424445%40%
1521
May1st to 15thNight
18%6%26%5%345%5%6%34%
1484
16th to endNight
11%5%36%5%2445%7%42%
1398
June1st to 15thNight
10%5%25%5%35%5%5%8%42%
1320
16th to endNight
7%5%25%6%26%5%6%9%42%
1320
July1st to 15thNight
6%3145%35%35%8%53%
1320
16th to endNight
6%31441446%8%52%
1401
August1st to 15thNight
6%325%32345%8%53%
1452
16th to endNight
11%424423347%50%
1695
September1st to 15thNight
13%224433345%52%
1699
16th to endNight
10%6%145%33346%49%
1815
October1st to 15thNight
21%6%24312346%42%
1846
16th to endNight
27%9%36%33334431%
2288
November1st to 15thNight
18%12%44423346%34%
2276
16th to endNight
22%18%6%9%5%23335%18%
2340
December1st to 15thNight
22%23%11%11%6%2222311%
2508
16th to endNight
22%22%10%11%5%2323411%
2688

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
76%7%7%6%1
1433
16th to endDay
81%36%5%2
1536
February1st to 15thDay
72%6%6%12%1
1650
16th to endDay
64%8%11%11%4
1580
March1st to 15thDay
55%6%13%17%6%
1809
16th to endDay
45%5%15%24%6%1
2100
April1st to 15thDay
51%5%9%20%12%
1971
16th to endDay
42%6%13%19%13%3
2109
May1st to 15thDay
45%6%13%24%9%
2136
16th to endDay
35%7%13%28%13%1
2364
June1st to 15thDay
36%7%14%24%16%
2310
16th to endDay
32%7%16%22%19%1
2310
July1st to 15thDay
28%7%13%28%19%2
2161
16th to endDay
30%8%15%26%16%3
2292
August1st to 15thDay
31%6%14%31%13%2
2163
16th to endDay
33%6%13%25%17%2
2153
September1st to 15thDay
36%7%13%26%13%1
1920
16th to endDay
38%6%13%26%14%
1815
October1st to 15thDay
47%5%10%23%12%
1780
16th to endDay
58%6%15%13%5%
1584
November1st to 15thDay
51%7%10%19%10%
1582
16th to endDay
70%5%10%11%2
1620
December1st to 15thDay
81%36%6%2
1449
16th to endDay
79%5%7%6%1
1536
January1st to 15thNight
77%5%5%8%2
2506
16th to endNight
76%7%9%5%1
2688
February1st to 15thNight
71%48%11%3
2210
16th to endNight
65%5%9%14%5%
1893
March1st to 15thNight
51%6%12%18%9%1
2151
16th to endNight
46%5%11%24%9%1
1977
April1st to 15thNight
50%5%8%17%15%1
1647
16th to endNight
44%5%9%19%15%5%
1521
May1st to 15thNight
48%6%11%21%11%1
1485
16th to endNight
40%7%11%22%15%3
1400
June1st to 15thNight
38%6%11%26%15%1
1320
16th to endNight
36%8%13%22%16%1
1320
July1st to 15thNight
29%6%12%26%22%3
1240
16th to endNight
29%8%14%24%20%2
1305
August1st to 15thNight
28%6%10%33%18%2
1443
16th to endNight
33%6%9%27%19%3
1695
September1st to 15thNight
33%5%13%27%18%1
1699
16th to endNight
36%5%11%29%14%1
1815
October1st to 15thNight
43%49%26%14%
1846
16th to endNight
56%5%13%16%7%
2288
November1st to 15thNight
52%6%10%18%11%1
2276
16th to endNight
69%5%10%12%2
2340
December1st to 15thNight
80%45%5%2
2508
16th to endNight
78%5%9%5%1
2688

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
25%12%24%36%1
90
16th to endDay
30%229%31%7%
96
February1st to 15thDay
15%17%47%16%2
90
16th to endDay
22%8%28%24%14%1
81
March1st to 15thDay
28%13%26%22%9%1
99
16th to endDay
22%5%26%28%13%2
260
April1st to 15thDay
27%7%25%28%9%1
210
16th to endDay
21%424%28%14%7%
210
May1st to 15thDay
26%324%27%12%5%
228
16th to endDay
11%325%31%20%6%
404
June1st to 15thDay
13%323%37%17%5%
420
16th to endDay
10%423%37%18%6%
420
July1st to 15thDay
6%123%34%23%11%
400
16th to endDay
8%119%38%23%8%
445
August1st to 15thDay
9%113%30%30%16%
286
16th to endDay
16%211%30%25%13%
268
September1st to 15thDay
14%29%35%26%11%
255
16th to endDay
12%317%22%30%13%
254
October1st to 15thDay
17%6%21%26%22%5%
236
16th to endDay
20%8%35%31%4
96
November1st to 15thDay
12%10%23%32%17%4
90
16th to endDay
32%13%30%12%12%
90
December1st to 15thDay
32%20%31%12%31
90
16th to endDay
30%27%35%7%
96
January1st to 15thNight
26%14%31%20%7%
900
16th to endNight
20%9%34%29%4
960
February1st to 15thNight
22%10%34%25%6%
742
16th to endNight
24%10%30%27%7%
631
March1st to 15thNight
21%8%27%31%9%
720
16th to endNight
15%5%30%32%14%1
682
April1st to 15thNight
21%5%29%34%7%1
494
16th to endNight
20%426%34%12%1
495
May1st to 15thNight
18%325%36%14%1
495
16th to endNight
14%218%38%24%1
515
June1st to 15thNight
12%220%40%23%1
495
16th to endNight
9%218%37%29%2
495
July1st to 15thNight
8%113%39%32%4
465
16th to endNight
7%113%41%32%3
522
August1st to 15thNight
7%11%42%31%5%
494
16th to endNight
12%111%35%33%5%
525
September1st to 15thNight
13%313%38%25%6%
544
16th to endNight
13%417%28%28%6%
657
October1st to 15thNight
25%417%30%20%2
660
16th to endNight
31%8%30%20%7%
704
November1st to 15thNight
24%8%27%27%11%
700
16th to endNight
31%13%25%22%6%
720
December1st to 15thNight
33%13%30%18%4
888
16th to endNight
31%10%34%19%3
960
Page generated at 2017-03-25 12:39:50. Version ac04

Copyright 2017 A. Danko


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