Heaven's Gate
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Heaven's Gate clear sky chart from 2005-11-05 to

2017-09-12
.

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
37%
14784
13%
46932
11%
14755
41%
14755
19%
32799

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%
717
8%
2506
5%
716
24%
716
9%
1982
January16th to endNight
30%
768
10%
2688
9%
768
34%
768
13%
2026
February1st to 15thNight
20%
700
5%
2318
3%
696
22%
696
8%
1907
February16th to endNight
22%
632
9%
1895
5%
632
27%
632
10%
1551
March1st to 15thNight
23%
720
5%
2160
2%
720
27%
720
12%
1720
March16th to endNight
21%
768
5%
2031
2%
768
23%
768
11%
1683
April1st to 15thNight
30%
719
7%
1799
3%
719
31%
719
15%
1439
April16th to endNight
37%
560
14%
1640
10%
560
39%
560
19%
1188
May1st to 15thNight
42%
483
15%
1563
12%
483
46%
483
23%
999
May16th to endNight
46%
374
9%
1496
13%
374
49%
374
16%
1003
June1st to 15thNight
43%
360
7%
1440
10%
360
46%
360
16%
956
June16th to endNight
58%
360
16%
1440
22%
360
64%
360
31%
746
July1st to 15thNight
77%
340
19%
1360
30%
340
81%
340
46%
566
July16th to endNight
74%
376
31%
1416
41%
354
82%
354
56%
523
August1st to 15thNight
73%
438
29%
1510
29%
436
78%
436
49%
678
August16th to endNight
66%
675
31%
1821
21%
675
69%
675
56%
914
September1st to 15thNight
71%
706
30%
1798
18%
706
75%
706
56%
953
September16th to endNight
57%
656
28%
1815
22%
656
61%
656
37%
1091
October1st to 15thNight
44%
660
19%
1881
16%
660
48%
660
27%
1250
October16th to endNight
37%
704
13%
2288
11%
704
41%
704
17%
1650
November1st to 15thNight
26%
700
12%
2275
8%
700
33%
700
14%
1730
November16th to endNight
22%
720
9%
2424
6%
720
27%
720
13%
1816
December1st to 15thNight
20%
858
5%
2658
2%
858
23%
858
10%
2156
December16th to endNight
15%
790
7%
2710
4%
790
18%
790
7%
2272

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%12%46%5%24445%37%
47733
Night
13%12%46%5%24446%35%
47102
Cloud CoverDay
10%11%46%6%34446%37%
47734
Night
11%11%46%5%3445%6%35%
47105
TransparencyDay
48%6%9%17%13%4
47405
Night
49%6%11%18%10%3
46933
SeeingDay
17%22%32%20%5%1
5310
Night
18%11%28%28%12%1
14793

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
11%16%6%9%7%3445%6%24%
1432
16th to endDay
14%18%7%8%5%23446%24%
1536
February1st to 15thDay
14%19%8%9%5%2445%5%21%
1542
16th to endDay
10%24%10%12%7%34335%16%
1579
March1st to 15thDay
14%21%7%10%6%45%44417%
1800
16th to endDay
14%23%8%10%7%2443413%
2190
April1st to 15thDay
15%24%5%8%5%33345%19%
2149
16th to endDay
17%19%47%5%2334428%
2319
May1st to 15thDay
14%13%35%5%33446%35%
2385
16th to endDay
23%12%37%5%35%445%23%
2615
June1st to 15thDay
21%9%36%5%345%45%28%
2520
16th to endDay
11%42442335%5%51%
2520
July1st to 15thDay
431442446%6%59%
2520
16th to endDay
212213245%71%
2657
August1st to 15thDay
421232345%6%62%
2442
16th to endDay
4213323345%65%
2378
September1st to 15thDay
5%113323336%65%
2081
16th to endDay
10%7%24423436%50%
1815
October1st to 15thDay
15%11%36%5%2334440%
1747
16th to endDay
20%12%35%434346%30%
1584
November1st to 15thDay
17%19%45%434446%24%
1584
16th to endDay
12%17%6%7%6%345%45%26%
1536
December1st to 15thDay
15%20%8%10%6%3345%317%
1284
16th to endDay
15%19%8%10%6%4434319%
1518
January1st to 15thNight
18%17%5%8%5%24346%23%
2506
16th to endNight
12%18%6%6%5%2435%5%27%
2688
February1st to 15thNight
17%17%6%8%6%3443322%
2307
16th to endNight
11%20%7%10%6%35%45%5%19%
1895
March1st to 15thNight
15%16%6%7%6%345%5%6%22%
2160
16th to endNight
15%17%6%7%5%345%6%7%20%
2028
April1st to 15thNight
14%18%5%8%6%3445%5%23%
1799
16th to endNight
18%15%35%423345%32%
1640
May1st to 15thNight
13%12%25%323345%42%
1563
16th to endNight
18%9%35%6%2445%8%30%
1496
June1st to 15thNight
22%6%25%42445%7%34%
1440
16th to endNight
11%41333435%6%52%
1440
July1st to 15thNight
412323446%66%
1440
16th to endNight
222112346%71%
1512
August1st to 15thNight
421232335%6%63%
1518
16th to endNight
4212224345%66%
1821
September1st to 15thNight
421232335%5%65%
1798
16th to endNight
13%6%14213336%52%
1815
October1st to 15thNight
14%8%26%424345%44%
1881
16th to endNight
17%11%36%6%34345%33%
2288
November1st to 15thNight
19%14%45%435%446%28%
2275
16th to endNight
15%18%6%6%433345%27%
2424
December1st to 15thNight
14%18%5%8%6%36%446%22%
2658
16th to endNight
13%19%8%10%7%35%345%17%
2710

Percentage Cloud Cover SW (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
9%14%7%10%7%345%5%6%25%
1432
16th to endDay
10%17%6%8%6%25%45%6%25%
1536
February1st to 15thDay
9%16%8%10%7%35%45%6%21%
1542
16th to endDay
6%20%9%13%9%35%44417%
1579
March1st to 15thDay
9%16%8%10%9%5%7%6%45%18%
1800
16th to endDay
10%23%8%10%8%46%44413%
2191
April1st to 15thDay
13%20%7%10%6%3445%5%19%
2149
16th to endDay
17%17%47%5%24336%27%
2319
May1st to 15thDay
12%11%35%5%34447%35%
2385
16th to endDay
21%12%47%6%35%445%23%
2615
June1st to 15thDay
18%9%36%6%345%5%6%28%
2520
16th to endDay
10%424433446%51%
2520
July1st to 15thDay
3333245%6%6%59%
2520
16th to endDay
212312346%71%
2657
August1st to 15thDay
42123235%5%7%61%
2442
16th to endDay
3313313345%66%
2378
September1st to 15thDay
4213324345%65%
2081
16th to endDay
9%5%245%23435%51%
1815
October1st to 15thDay
13%9%36%6%34335%39%
1747
16th to endDay
17%10%46%6%3445%6%30%
1584
November1st to 15thDay
13%17%47%6%3445%6%24%
1584
16th to endDay
8%14%7%8%7%445%5%7%26%
1536
December1st to 15thDay
12%16%7%9%10%45%45%418%
1284
16th to endDay
11%16%9%11%8%35%445%19%
1518
January1st to 15thNight
14%15%5%8%8%35%346%23%
2506
16th to endNight
9%17%5%9%5%34446%28%
2688
February1st to 15thNight
11%16%7%10%7%35%445%21%
2307
16th to endNight
8%17%6%11%8%45%5%5%7%20%
1895
March1st to 15thNight
9%15%6%9%6%36%5%5%6%24%
2160
16th to endNight
13%14%6%8%6%46%6%6%6%20%
2031
April1st to 15thNight
11%16%6%8%6%45%5%5%5%24%
1799
16th to endNight
18%12%37%424446%32%
1640
May1st to 15thNight
12%10%2442345%5%42%
1563
16th to endNight
16%9%35%6%3445%9%30%
1496
June1st to 15thNight
21%6%35%5%2445%7%34%
1440
16th to endNight
10%313325%447%53%
1440
July1st to 15thNight
31222345%6%66%
1440
16th to endNight
21111235%6%71%
1512
August1st to 15thNight
321221345%8%63%
1518
16th to endNight
32222335%5%66%
1821
September1st to 15thNight
411222445%6%65%
1798
16th to endNight
11%5%24322346%52%
1815
October1st to 15thNight
13%7%25%5%34445%42%
1881
16th to endNight
15%10%35%7%34446%33%
2288
November1st to 15thNight
16%13%46%5%35%5%46%28%
2275
16th to endNight
11%15%6%8%6%34446%28%
2424
December1st to 15thNight
10%15%6%8%7%46%5%6%6%22%
2658
16th to endNight
10%18%7%10%8%45%45%5%18%
2710

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
60%9%13%11%3
1432
16th to endDay
61%7%11%12%5%2
1536
February1st to 15thDay
63%10%11%11%2
1542
16th to endDay
71%6%9%10%1
1579
March1st to 15thDay
69%7%9%9%3
1800
16th to endDay
73%6%8%10%1
2191
April1st to 15thDay
66%6%12%10%3
2149
16th to endDay
59%5%10%18%6%
2319
May1st to 15thDay
47%5%12%25%8%
2385
16th to endDay
62%5%10%15%5%
2619
June1st to 15thDay
55%5%8%19%8%1
2520
16th to endDay
33%48%28%20%4
2520
July1st to 15thDay
23%5%8%20%30%12%
2371
16th to endDay
13%35%16%37%22%
2490
August1st to 15thDay
21%46%21%31%14%
2425
16th to endDay
19%47%24%31%12%
2378
September1st to 15thDay
20%39%21%31%13%
2081
16th to endDay
34%410%25%20%4
1815
October1st to 15thDay
47%5%9%22%13%1
1747
16th to endDay
53%7%11%17%10%
1584
November1st to 15thDay
59%9%12%13%3
1584
16th to endDay
59%7%12%13%6%
1536
December1st to 15thDay
69%9%10%7%1
1284
16th to endDay
69%8%11%8%1
1518
January1st to 15thNight
62%8%10%12%41
2506
16th to endNight
56%8%11%14%7%1
2688
February1st to 15thNight
66%8%10%11%3
2318
16th to endNight
65%7%10%13%21
1895
March1st to 15thNight
61%8%12%13%4
2160
16th to endNight
62%10%12%13%1
2031
April1st to 15thNight
60%6%14%14%3
1799
16th to endNight
53%5%12%23%5%
1640
May1st to 15thNight
42%5%13%29%8%
1564
16th to endNight
49%5%16%21%6%
1496
June1st to 15thNight
47%7%14%21%7%1
1440
16th to endNight
30%5%13%30%16%3
1440
July1st to 15thNight
17%410%24%30%12%
1360
16th to endNight
12%3424%36%18%
1416
August1st to 15thNight
18%48%26%28%14%
1510
16th to endNight
17%39%26%29%13%
1821
September1st to 15thNight
18%48%25%30%12%
1798
16th to endNight
32%410%23%21%7%
1815
October1st to 15thNight
41%5%11%23%15%1
1881
16th to endNight
51%7%11%16%12%
2288
November1st to 15thNight
55%9%11%17%5%1
2275
16th to endNight
58%6%11%16%6%1
2424
December1st to 15thNight
62%10%14%11%2
2658
16th to endNight
68%8%10%9%2
2710

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%15%40%16%13%1
60
16th to endDay
15%21%35%20%6%
64
February1st to 15thDay
18%31%26%19%4
142
16th to endDay
23%33%31%9%1
238
March1st to 15thDay
23%39%25%10%1
270
16th to endDay
28%38%22%9%1
288
April1st to 15thDay
21%28%29%13%5%1
269
16th to endDay
35%22%24%13%2
270
May1st to 15thDay
25%23%31%15%3
288
16th to endDay
29%13%25%21%6%3
330
June1st to 15thDay
19%22%32%19%5%1
315
16th to endDay
10%22%35%25%5%1
315
July1st to 15thDay
6%15%38%28%9%1
305
16th to endDay
320%41%27%6%1
327
August1st to 15thDay
7%10%38%33%7%2
315
16th to endDay
5%13%36%30%12%2
332
September1st to 15thDay
7%19%30%27%11%4
300
16th to endDay
12%14%39%25%7%
255
October1st to 15thDay
17%25%34%17%4
241
16th to endDay
27%17%35%13%6%
96
November1st to 15thDay
24%21%34%15%4
90
16th to endDay
21%23%40%13%1
76
December1st to 15thDay
31%26%30%8%3
60
16th to endDay
18%29%34%10%41
64
January1st to 15thNight
26%15%34%18%5%
720
16th to endNight
20%12%30%29%5%
768
February1st to 15thNight
23%15%35%21%4
704
16th to endNight
19%21%33%20%5%
632
March1st to 15thNight
17%20%35%19%7%
720
16th to endNight
20%17%36%21%3
768
April1st to 15thNight
19%13%29%22%12%1
719
16th to endNight
25%8%24%29%10%1
560
May1st to 15thNight
20%6%24%33%13%1
484
16th to endNight
19%418%33%21%1
375
June1st to 15thNight
22%324%31%17%1
360
16th to endNight
12%420%41%20%
360
July1st to 15thNight
5%112%52%26%
340
16th to endNight
3216%52%25%
376
August1st to 15thNight
5%16%44%31%
438
16th to endNight
4222%37%29%2
675
September1st to 15thNight
5%117%41%27%5%
706
16th to endNight
14%420%33%22%5%
656
October1st to 15thNight
18%7%24%33%14%1
660
16th to endNight
22%7%28%29%9%3
704
November1st to 15thNight
23%13%34%24%4
700
16th to endNight
24%17%31%18%6%1
720
December1st to 15thNight
21%17%37%22%1
858
16th to endNight
21%22%36%16%2
790
Page generated at 2017-09-13 05:39:18. Version ac04

Copyright 2017 A. Danko


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