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 2018-01-20.

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%
16543
13%
48445
10%
16501
40%
16501
18%
35671

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%
975
5%
2716
2%
970
16%
970
6%
2412
January16th to endNight
16%
985
4%
2757
2%
985
18%
985
6%
2453
February1st to 15thNight
18%
739
6%
2210
2%
739
22%
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%
705
18%
2049
13%
705
43%
705
22%
1421
April1st to 15thNight
35%
539
13%
1797
11%
539
40%
539
17%
1252
April16th to endNight
42%
540
20%
1659
13%
540
49%
540
24%
1103
May1st to 15thNight
43%
540
15%
1620
9%
540
47%
540
21%
1116
May16th to endNight
52%
562
15%
1531
11%
561
55%
561
28%
1028
June1st to 15thNight
57%
540
15%
1440
10%
540
61%
540
33%
918
June16th to endNight
59%
540
14%
1440
10%
540
61%
540
31%
939
July1st to 15thNight
69%
510
16%
1360
13%
510
70%
510
40%
808
July16th to endNight
71%
564
20%
1417
18%
531
71%
531
39%
862
August1st to 15thNight
69%
539
22%
1575
19%
536
71%
536
38%
900
August16th to endNight
66%
573
21%
1850
19%
573
69%
573
31%
1079
September1st to 15thNight
64%
594
23%
1854
23%
594
67%
594
33%
1079
September16th to endNight
59%
717
23%
1980
19%
717
61%
717
33%
1239
October1st to 15thNight
48%
720
21%
2015
16%
720
51%
720
27%
1356
October16th to endNight
25%
768
12%
2496
8%
768
31%
768
14%
1855
November1st to 15thNight
32%
760
16%
2471
14%
760
37%
760
15%
1796
November16th to endNight
21%
780
9%
2535
6%
780
25%
780
9%
2063
December1st to 15thNight
12%
962
3%
2717
1%
962
13%
962
5%
2441
December16th to endNight
11%
1040
4%
2912
1%
1040
14%
1040
5%
2613

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%
49088
Night
16%11%5%7%5%24345%32%
48613
Cloud CoverDay
14%9%46%5%3445%7%35%
49097
Night
16%11%5%7%5%34345%32%
48618
TransparencyDay
48%6%12%20%11%1
48774
Night
54%5%10%17%10%1
48445
SeeingDay
16%5%22%30%17%6%
6388
Night
20%6%25%29%14%1
16547

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
17%15%8%12%10%46%43311%
1552
16th to endDay
14%19%10%15%11%35%32310%
1571
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
16%9%45%42335%7%36%
2184
April1st to 15thDay
20%10%35%423347%33%
2151
16th to endDay
16%6%25%3345%5%7%39%
2301
May1st to 15thDay
18%5%25%42445%8%37%
2331
16th to endDay
10%325%43445%8%47%
2581
June1st to 15thDay
10%41443445%8%46%
2520
16th to endDay
8%4144345%5%9%47%
2520
July1st to 15thDay
5%413325%5%6%9%52%
2520
16th to endDay
8%31342446%9%50%
2655
August1st to 15thDay
8%4244235%6%9%47%
2376
16th to endDay
11%425%42436%8%48%
2350
September1st to 15thDay
12%42443445%8%46%
2094
16th to endDay
10%5%24435%36%8%43%
1980
October1st to 15thDay
19%6%25%6%24445%38%
1941
16th to endDay
25%8%37%6%43446%25%
1728
November1st to 15thDay
18%11%36%5%25%345%33%
1717
16th to endDay
21%20%5%8%5%2333420%
1755
December1st to 15thDay
18%24%13%12%6%2212311%
1570
16th to endDay
20%22%10%11%7%2433310%
1664
January1st to 15thNight
20%15%9%12%11%3333313%
2716
16th to endNight
14%16%12%12%11%3443412%
2757
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
16%8%45%5%3435%5%38%
2049
April1st to 15thNight
19%9%45%42445%6%32%
1797
16th to endNight
17%6%25%424445%40%
1659
May1st to 15thNight
18%6%26%5%3445%6%35%
1620
16th to endNight
11%5%36%5%25%45%7%41%
1529
June1st to 15thNight
9%5%25%5%3445%8%45%
1440
16th to endNight
8%435%6%25%5%6%8%42%
1440
July1st to 15thNight
6%314435%36%8%52%
1440
16th to endNight
6%31341446%8%52%
1513
August1st to 15thNight
6%3244235%5%8%52%
1584
16th to endNight
11%42442335%7%50%
1850
September1st to 15thNight
12%31433335%5%52%
1854
16th to endNight
9%5%245%34346%50%
1980
October1st to 15thNight
23%6%24313345%41%
2015
16th to endNight
28%9%26%42333431%
2496
November1st to 15thNight
19%12%35%433345%32%
2471
16th to endNight
21%20%6%8%5%13345%19%
2535
December1st to 15thNight
21%24%10%11%5%2222311%
2717
16th to endNight
21%22%9%12%6%2323411%
2912

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%15%8%12%10%5%6%44312%
1552
16th to endDay
14%19%10%14%10%45%32310%
1571
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
16%9%45%42345%7%36%
2183
April1st to 15thDay
20%10%45%423347%33%
2151
16th to endDay
16%6%25%4235%5%7%38%
2301
May1st to 15thDay
18%5%25%42445%8%37%
2331
16th to endDay
9%426%42445%8%47%
2581
June1st to 15thDay
10%424435%45%9%46%
2520
16th to endDay
9%414435%45%9%47%
2520
July1st to 15thDay
6%413335%5%6%9%51%
2520
16th to endDay
8%31342446%9%49%
2655
August1st to 15thDay
8%325%42445%10%47%
2376
16th to endDay
12%42432336%8%47%
2350
September1st to 15thDay
12%5%2343445%8%46%
2094
16th to endDay
10%5%34435%36%9%43%
1980
October1st to 15thDay
18%7%25%5%34445%37%
1941
16th to endDay
24%8%27%6%3435%7%25%
1728
November1st to 15thDay
17%11%46%5%25%35%5%32%
1717
16th to endDay
21%18%5%8%5%2433420%
1755
December1st to 15thDay
18%24%12%11%6%2312411%
1570
16th to endDay
20%21%10%10%8%2424310%
1664
January1st to 15thNight
20%15%9%12%10%3433313%
2716
16th to endNight
14%15%12%12%10%4433412%
2757
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
16%8%35%434346%38%
2049
April1st to 15thNight
19%9%35%5%2445%6%32%
1797
16th to endNight
17%6%25%424446%40%
1659
May1st to 15thNight
18%6%26%5%3445%6%35%
1619
16th to endNight
11%5%36%5%25%45%7%42%
1529
June1st to 15thNight
9%5%245%345%5%8%45%
1440
16th to endNight
8%425%5%26%5%6%8%42%
1440
July1st to 15thNight
6%3145%35%35%8%53%
1440
16th to endNight
6%31442446%9%52%
1513
August1st to 15thNight
6%32432445%8%52%
1584
16th to endNight
11%424423347%50%
1850
September1st to 15thNight
12%21442335%5%52%
1854
16th to endNight
9%5%145%33346%50%
1980
October1st to 15thNight
22%6%24312346%41%
2015
16th to endNight
27%9%36%32333431%
2496
November1st to 15thNight
19%12%45%5%23346%32%
2471
16th to endNight
21%18%6%9%5%23335%20%
2535
December1st to 15thNight
21%23%11%11%5%2222312%
2717
16th to endNight
21%21%9%11%7%2323411%
2912

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
1553
16th to endDay
80%47%5%2
1571
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
47%5%15%24%6%1
2184
April1st to 15thDay
51%5%9%20%12%
2151
16th to endDay
42%6%13%19%14%3
2301
May1st to 15thDay
44%6%12%24%10%1
2331
16th to endDay
35%7%14%28%13%1
2585
June1st to 15thDay
34%7%14%25%17%
2520
16th to endDay
32%7%16%23%18%1
2520
July1st to 15thDay
28%7%13%28%19%2
2371
16th to endDay
29%7%14%26%17%2
2488
August1st to 15thDay
31%7%14%31%13%1
2361
16th to endDay
33%6%13%26%16%2
2350
September1st to 15thDay
35%6%13%27%14%2
2094
16th to endDay
37%6%13%26%15%
1980
October1st to 15thDay
48%5%10%22%12%1
1941
16th to endDay
58%5%15%13%5%
1728
November1st to 15thDay
52%6%10%19%9%
1717
16th to endDay
68%410%11%3
1755
December1st to 15thDay
81%36%6%2
1570
16th to endDay
79%5%7%5%
1664
January1st to 15thNight
77%5%6%7%2
2716
16th to endNight
75%7%10%5%1
2757
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
47%5%11%24%9%1
2049
April1st to 15thNight
51%5%8%17%15%1
1797
16th to endNight
44%5%9%19%15%5%
1659
May1st to 15thNight
47%6%10%20%12%2
1620
16th to endNight
41%6%11%22%15%2
1531
June1st to 15thNight
35%6%11%26%18%1
1440
16th to endNight
36%8%13%23%16%1
1440
July1st to 15thNight
28%6%12%27%21%2
1360
16th to endNight
28%8%14%24%20%3
1417
August1st to 15thNight
28%6%12%32%17%2
1575
16th to endNight
33%6%9%28%18%3
1850
September1st to 15thNight
32%6%12%27%19%2
1854
16th to endNight
35%5%11%30%15%1
1980
October1st to 15thNight
44%49%25%14%1
2015
16th to endNight
57%5%12%16%7%
2496
November1st to 15thNight
53%6%10%17%10%1
2471
16th to endNight
67%5%11%12%2
2535
December1st to 15thNight
80%46%6%3
2717
16th to endNight
78%5%8%5%1
2912

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%9%25%37%2
135
16th to endDay
27%332%29%6%
109
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
27%5%24%27%12%2
288
April1st to 15thDay
28%6%26%28%8%1
270
16th to endDay
21%5%27%28%12%5%
270
May1st to 15thDay
23%5%23%27%14%4
288
16th to endDay
12%428%30%18%6%
481
June1st to 15thDay
11%222%39%18%5%
495
16th to endDay
10%426%36%15%5%
495
July1st to 15thDay
5%122%36%23%10%
475
16th to endDay
8%118%37%24%9%
515
August1st to 15thDay
8%112%30%31%15%
349
16th to endDay
16%210%31%25%13%
332
September1st to 15thDay
12%29%34%25%15%
315
16th to endDay
10%416%20%33%15%
314
October1st to 15thDay
20%6%20%27%19%5%
294
16th to endDay
25%7%29%29%6%
144
November1st to 15thDay
21%8%25%30%11%2
135
16th to endDay
28%15%32%14%9%
135
December1st to 15thDay
31%22%28%11%5%
135
16th to endDay
25%25%36%13%
144
January1st to 15thNight
26%13%30%21%6%
975
16th to endNight
20%9%34%30%4
985
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
17%5%30%31%14%1
705
April1st to 15thNight
22%5%29%34%7%
539
16th to endNight
20%426%34%12%1
540
May1st to 15thNight
19%325%35%14%1
540
16th to endNight
14%220%37%23%2
563
June1st to 15thNight
11%120%41%24%1
540
16th to endNight
9%220%37%27%2
540
July1st to 15thNight
8%13%39%33%4
510
16th to endNight
6%113%41%33%3
564
August1st to 15thNight
7%11%42%31%5%
539
16th to endNight
13%111%34%32%6%
573
September1st to 15thNight
12%313%37%26%7%
594
16th to endNight
12%317%29%29%7%
717
October1st to 15thNight
26%417%30%19%2
720
16th to endNight
32%8%29%21%7%1
768
November1st to 15thNight
25%8%27%26%11%
760
16th to endNight
31%13%26%22%5%
780
December1st to 15thNight
32%13%30%19%4
962
16th to endNight
30%10%35%19%3
1040
Page generated at 2018-01-21 12:19:29. Version ac04

Copyright 2018 A. Danko


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