Squirrel Cove
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Squirrel Cove clear sky chart from 2005-11-05 to 2017-09-20.

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
30%
14482
7%
46794
5%
14453
33%
14453
11%
36314

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
19%
750
9%
2686
6%
746
24%
746
7%
2266
January16th to endNight
23%
797
5%
2815
4%
797
25%
797
6%
2368
February1st to 15thNight
21%
700
6%
2288
4%
700
25%
700
6%
1937
February16th to endNight
28%
632
10%
2053
8%
632
32%
632
11%
1577
March1st to 15thNight
17%
720
3%
2052
2%
720
18%
720
7%
1776
March16th to endNight
23%
768
5%
2112
3%
768
24%
768
7%
1815
April1st to 15thNight
31%
645
6%
1728
3%
645
32%
645
12%
1419
April16th to endNight
23%
540
7%
1620
4%
540
27%
540
10%
1294
May1st to 15thNight
32%
359
9%
1440
11%
359
38%
359
11%
1001
May16th to endNight
34%
375
5%
1351
4%
374
36%
374
11%
1012
June1st to 15thNight
38%
360
1%
1260
1%
360
38%
360
14%
902
June16th to endNight
37%
360
3%
1260
0%
360
38%
360
12%
933
July1st to 15thNight
54%
340
5%
1190
3%
340
56%
340
27%
671
July16th to endNight
58%
376
10%
1239
9%
354
66%
354
31%
662
August1st to 15thNight
65%
472
13%
1546
15%
470
68%
470
31%
851
August16th to endNight
54%
573
15%
1719
11%
573
58%
573
26%
1080
September1st to 15thNight
59%
705
20%
1785
11%
705
61%
705
36%
1095
September16th to endNight
37%
675
12%
1882
7%
675
40%
675
17%
1393
October1st to 15thNight
34%
660
7%
1980
6%
660
36%
660
15%
1457
October16th to endNight
24%
704
4%
2232
3%
704
26%
704
7%
1879
November1st to 15thNight
12%
700
4%
2450
1%
700
16%
700
5%
2148
November16th to endNight
15%
721
5%
2526
2%
721
20%
721
6%
2104
December1st to 15thNight
20%
750
5%
2700
3%
750
23%
750
7%
2238
December16th to endNight
14%
800
5%
2880
3%
800
17%
800
6%
2436

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
23%7%35%424446%32%
48088
Night
28%8%35%424345%28%
46938
TransparencyDay
54%9%14%15%5%
47737
Night
59%7%13%13%5%
46794
SeeingDay
22%16%20%23%15%2
6406
Night
28%18%16%20%13%1
14487

By Month

Percentage Cloud Cover NW (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
39%11%47%5%1342315%
1253
16th to endDay
38%12%47%433345%12%
1407
February1st to 15thDay
37%10%36%33433418%
1576
16th to endDay
26%10%445%25%447%22%
1421
March1st to 15thDay
37%11%35%4245%5%414%
1908
16th to endDay
27%11%48%6%34446%19%
2112
April1st to 15thDay
25%8%45%6%36%446%23%
2217
16th to endDay
28%8%25%5%33345%27%
2340
May1st to 15thDay
18%6%245%2446%7%36%
2511
16th to endDay
19%6%35%6%35%447%32%
2760
June1st to 15thDay
14%6%35%5%345%48%37%
2700
16th to endDay
17%6%26%5%35%5%5%7%34%
2700
July1st to 15thDay
12%313313447%54%
2700
16th to endDay
8%31331435%7%56%
2846
August1st to 15thDay
7%312324447%59%
2404
16th to endDay
12%4133235%47%49%
2483
September1st to 15thDay
11%414323346%53%
2173
16th to endDay
29%5%135%25%346%32%
1846
October1st to 15thDay
28%8%26%6%23335%29%
1650
16th to endDay
39%8%26%5%12346%18%
1638
November1st to 15thDay
42%7%46%6%3433315%
1408
16th to endDay
37%9%46%5%3343318%
1431
December1st to 15thDay
35%12%45%41333322%
1260
16th to endDay
39%11%36%43444314%
1344
January1st to 15thNight
39%9%36%42333319%
2686
16th to endNight
37%10%35%5%3435%416%
2815
February1st to 15thNight
37%9%36%5%2434418%
2276
16th to endNight
26%9%345%2434429%
2053
March1st to 15thNight
35%10%35%5%3434417%
2052
16th to endNight
30%8%37%5%45%45%5%19%
2108
April1st to 15thNight
25%8%35%6%35%46%6%24%
1728
16th to endNight
28%7%36%5%24445%26%
1620
May1st to 15thNight
20%7%35%435%5%46%33%
1439
16th to endNight
18%10%36%5%35%6%46%28%
1351
June1st to 15thNight
17%7%345%25%445%37%
1260
16th to endNight
16%6%48%7%25%46%6%31%
1260
July1st to 15thNight
10%42432345%6%51%
1260
16th to endNight
9%423213346%56%
1323
August1st to 15thNight
7%3135%23446%56%
1553
16th to endNight
12%42442345%7%48%
1719
September1st to 15thNight
8%323433436%56%
1785
16th to endNight
25%6%25%422345%36%
1882
October1st to 15thNight
25%6%35%323345%35%
1980
16th to endNight
41%7%25%423335%21%
2232
November1st to 15thNight
43%8%36%42333316%
2450
16th to endNight
35%11%36%6%2433418%
2526
December1st to 15thNight
37%10%45%42333320%
2700
16th to endNight
40%11%45%42323318%
2880

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
74%5%7%8%4
1253
16th to endDay
75%5%7%8%12
1407
February1st to 15thDay
69%9%7%6%32
1576
16th to endDay
61%9%13%10%4
1421
March1st to 15thDay
73%7%9%7%2
1908
16th to endDay
69%8%10%9%
2112
April1st to 15thDay
63%11%12%9%3
2217
16th to endDay
62%10%12%10%4
2340
May1st to 15thDay
49%9%16%18%6%
2511
16th to endDay
54%10%14%17%3
2764
June1st to 15thDay
47%13%16%17%31
2700
16th to endDay
51%13%14%15%4
2700
July1st to 15thDay
31%9%22%24%10%1
2541
16th to endDay
26%11%21%30%8%
2667
August1st to 15thDay
25%10%21%30%10%1
2387
16th to endDay
34%9%23%23%6%1
2483
September1st to 15thDay
33%8%19%22%14%1
2173
16th to endDay
52%10%15%14%6%
1846
October1st to 15thDay
59%8%11%13%6%
1650
16th to endDay
66%8%13%8%2
1638
November1st to 15thDay
75%7%7%5%21
1408
16th to endDay
70%6%8%9%4
1431
December1st to 15thDay
68%6%8%8%5%2
1260
16th to endDay
75%48%5%41
1344
January1st to 15thNight
72%5%7%8%5%1
2686
16th to endNight
70%7%8%8%3
2815
February1st to 15thNight
70%6%8%8%32
2288
16th to endNight
60%5%13%14%5%
2053
March1st to 15thNight
72%6%9%8%2
2052
16th to endNight
68%9%11%9%1
2112
April1st to 15thNight
61%9%11%14%2
1728
16th to endNight
61%9%11%14%4
1620
May1st to 15thNight
51%8%15%18%6%
1440
16th to endNight
54%9%18%13%3
1351
June1st to 15thNight
49%10%21%12%41
1260
16th to endNight
51%11%14%17%31
1260
July1st to 15thNight
31%7%23%21%14%1
1190
16th to endNight
27%7%26%30%7%
1239
August1st to 15thNight
28%8%21%29%11%1
1546
16th to endNight
34%9%22%24%7%2
1719
September1st to 15thNight
30%5%18%28%15%1
1785
16th to endNight
51%8%17%14%7%1
1882
October1st to 15thNight
51%9%17%16%6%
1980
16th to endNight
68%8%12%7%2
2232
November1st to 15thNight
76%6%7%5%31
2450
16th to endNight
69%6%7%9%5%
2526
December1st to 15thNight
69%6%9%8%41
2700
16th to endNight
72%6%8%8%4
2880

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
13%131%25%20%8%
60
16th to endDay
48%15%16%12%7%
112
February1st to 15thDay
38%18%16%15%11%
236
16th to endDay
27%19%20%18%11%1
211
March1st to 15thDay
43%25%15%9%4
264
16th to endDay
32%23%24%12%6%1
288
April1st to 15thDay
27%24%20%18%7%1
269
16th to endDay
27%20%25%18%7%
270
May1st to 15thDay
23%14%22%26%11%
288
16th to endDay
16%17%21%25%18%2
475
June1st to 15thDay
15%21%24%25%12%
495
16th to endDay
18%20%20%25%14%1
495
July1st to 15thDay
9%12%23%33%19%2
475
16th to endDay
6%16%16%28%29%2
515
August1st to 15thDay
7%6%16%33%30%6%
315
16th to endDay
14%10%18%34%18%3
332
September1st to 15thDay
14%9%21%28%20%5%
315
16th to endDay
33%10%19%18%14%2
272
October1st to 15thDay
30%14%22%17%12%2
255
16th to endDay
42%13%15%15%9%3
220
November1st to 15thDay
51%10%21%13%11
60
16th to endDay
41%13%13%8%8%15%
60
December1st to 15thDay
45%10%16%11%13%3
60
16th to endDay
34%6%28%21%7%1
64
January1st to 15thNight
37%20%15%16%8%1
750
16th to endNight
35%19%16%15%12%1
797
February1st to 15thNight
36%20%15%19%7%
704
16th to endNight
28%20%18%22%9%1
632
March1st to 15thNight
37%23%17%12%7%1
720
16th to endNight
29%23%18%14%11%1
768
April1st to 15thNight
25%20%16%24%11%1
645
16th to endNight
26%21%21%21%9%
540
May1st to 15thNight
24%19%16%21%17%1
360
16th to endNight
20%19%16%26%15%1
375
June1st to 15thNight
18%19%18%26%15%1
360
16th to endNight
17%18%18%28%15%1
360
July1st to 15thNight
9%15%14%29%29%2
340
16th to endNight
9%16%11%29%30%2
376
August1st to 15thNight
8%9%8%31%36%4
472
16th to endNight
14%10%13%32%27%
573
September1st to 15thNight
10%10%13%29%28%7%
705
16th to endNight
28%11%15%21%18%3
675
October1st to 15thNight
28%14%17%22%16%1
660
16th to endNight
41%15%14%17%9%2
704
November1st to 15thNight
42%19%21%12%4
700
16th to endNight
35%23%17%14%7%
721
December1st to 15thNight
35%20%18%18%6%
750
16th to endNight
40%21%20%13%4
800
Page generated at 2017-09-21 04:18:14. Version ac04

Copyright 2017 A. Danko


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