Baum Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Baum Lake clear sky chart from 2005-11-05 to 2017-09-21.

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
64%
15036
24%
46915
22%
15004
67%
15004
37%
26081

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
56%
718
17%
2506
16%
716
61%
716
27%
1496
January16th to endNight
53%
768
21%
2508
21%
768
56%
768
26%
1562
February1st to 15thNight
52%
697
16%
2288
16%
697
55%
697
25%
1454
February16th to endNight
51%
632
19%
1920
16%
632
56%
632
26%
1215
March1st to 15thNight
49%
720
13%
2058
11%
720
51%
720
25%
1390
March16th to endNight
48%
768
16%
2061
11%
768
52%
768
27%
1361
April1st to 15thNight
50%
719
16%
1799
8%
719
53%
719
30%
1220
April16th to endNight
57%
720
21%
1800
10%
720
60%
720
43%
1078
May1st to 15thNight
58%
458
24%
1538
20%
458
64%
458
40%
786
May16th to endNight
62%
374
18%
1496
20%
374
67%
374
30%
794
June1st to 15thNight
70%
360
21%
1440
27%
360
76%
360
35%
689
June16th to endNight
79%
360
31%
1440
43%
360
83%
360
56%
532
July1st to 15thNight
93%
340
31%
1360
45%
340
93%
340
67%
453
July16th to endNight
93%
442
39%
1477
45%
415
94%
415
72%
515
August1st to 15thNight
92%
538
38%
1611
33%
535
92%
535
71%
660
August16th to endNight
88%
750
44%
1896
29%
750
89%
750
81%
836
September1st to 15thNight
88%
720
42%
1800
28%
720
89%
720
80%
811
September16th to endNight
78%
680
38%
1850
33%
680
81%
680
63%
868
October1st to 15thNight
70%
660
28%
1980
28%
660
76%
660
47%
1001
October16th to endNight
70%
704
29%
2112
29%
704
74%
704
46%
1103
November1st to 15thNight
64%
700
20%
2271
20%
700
67%
700
28%
1375
November16th to endNight
55%
720
17%
2496
17%
720
58%
720
28%
1468
December1st to 15thNight
51%
720
17%
2520
16%
720
56%
720
22%
1601
December16th to endNight
44%
768
18%
2688
16%
768
50%
768
19%
1813

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
4313324446%60%
47957
Night
5%41332445%7%56%
47093
TransparencyDay
25%5%10%20%21%15%
47634
Night
27%7%12%21%19%11%
46916
SeeingDay
8%14%27%28%15%5%
5792
Night
6%5%18%39%27%2
15047

By Month

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
46%25%5%36%6%6%7%45%
1432
16th to endDay
6%7%245%36%5%5%7%44%
1713
February1st to 15thDay
6%435%6%35%5%6%8%43%
1576
16th to endDay
6%8%25%6%36%5%5%7%42%
1553
March1st to 15thDay
6%6%35%6%48%6%6%9%36%
1902
16th to endDay
6%7%15%5%45%6%6%9%40%
2161
April1st to 15thDay
6%6%35%6%36%47%7%41%
2149
16th to endDay
6%413424447%56%
2160
May1st to 15thDay
431232335%7%61%
2408
16th to endDay
7%424424447%53%
2615
June1st to 15thDay
5%213324346%61%
2520
16th to endDay
212113479%
2520
July1st to 15thDay
11111222382%
2520
16th to endDay
11112385%
2589
August1st to 15thDay
1111223381%
2340
16th to endDay
1112386%
2305
September1st to 15thDay
111123482%
2160
16th to endDay
321212236%74%
1899
October1st to 15thDay
4213323345%66%
1650
16th to endDay
5%3145%2335%8%56%
1760
November1st to 15thDay
7%424435%5%5%8%48%
1587
16th to endDay
5%5%25%5%36%5%5%8%46%
1462
December1st to 15thDay
7%6%25%6%45%5%6%8%40%
1440
16th to endDay
7%8%36%6%46%5%6%7%37%
1536
January1st to 15thNight
5%5%24435%5%6%8%46%
2506
16th to endNight
7%7%36%435%5%5%5%46%
2508
February1st to 15thNight
5%7%25%5%36%5%6%9%42%
2276
16th to endNight
6%9%345%45%46%8%42%
1920
March1st to 15thNight
5%9%25%5%36%5%6%11%39%
2058
16th to endNight
5%5%34435%7%6%10%44%
2061
April1st to 15thNight
6%5%25%436%46%9%44%
1799
16th to endNight
7%41332335%7%57%
1800
May1st to 15thNight
5%314423336%61%
1538
16th to endNight
7%4233245%5%6%54%
1496
June1st to 15thNight
7%21222435%6%60%
1440
16th to endNight
2111211235%76%
1440
July1st to 15thNight
1111223480%
1440
16th to endNight
11112484%
1578
August1st to 15thNight
11111112481%
1620
16th to endNight
111112385%
1896
September1st to 15thNight
111112484%
1800
16th to endNight
211212335%74%
1850
October1st to 15thNight
5%312322246%66%
1980
16th to endNight
5%31232335%7%61%
2112
November1st to 15thNight
6%5%14335%5%6%9%46%
2271
16th to endNight
5%6%24435%5%7%8%46%
2496
December1st to 15thNight
9%6%25%5%35%46%7%42%
2520
16th to endNight
8%8%35%6%35%5%48%38%
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
36%9%15%24%11%2
1432
16th to endDay
39%8%11%20%12%7%
1713
February1st to 15thDay
36%8%16%20%15%1
1576
16th to endDay
39%8%15%26%7%2
1553
March1st to 15thDay
42%10%13%17%13%1
1902
16th to endDay
37%12%18%18%9%3
2161
April1st to 15thDay
41%7%15%20%12%1
2149
16th to endDay
28%6%15%26%18%4
2160
May1st to 15thDay
23%413%28%22%7%
2408
16th to endDay
32%5%13%24%19%5%
2619
June1st to 15thDay
25%410%21%24%13%
2520
16th to endDay
11%26%19%39%21%
2520
July1st to 15thDay
8%2315%31%38%
2371
16th to endDay
6%2311%26%49%
2427
August1st to 15thDay
9%2317%27%39%
2324
16th to endDay
6%1314%34%39%
2305
September1st to 15thDay
7%2414%34%37%
2160
16th to endDay
13%38%24%30%19%
1899
October1st to 15thDay
22%49%26%27%9%
1650
16th to endDay
26%6%15%21%21%9%
1760
November1st to 15thDay
34%7%16%23%12%5%
1587
16th to endDay
33%10%14%21%15%3
1462
December1st to 15thDay
38%12%13%21%13%
1440
16th to endDay
44%8%11%21%10%2
1536
January1st to 15thNight
33%9%18%21%13%2
2506
16th to endNight
37%7%11%18%15%8%
2508
February1st to 15thNight
36%10%15%19%14%3
2288
16th to endNight
37%8%16%24%11%2
1920
March1st to 15thNight
38%11%18%15%12%2
2058
16th to endNight
33%13%19%19%10%2
2061
April1st to 15thNight
36%9%19%23%8%2
1799
16th to endNight
27%6%17%30%15%4
1800
May1st to 15thNight
24%5%11%29%20%7%
1539
16th to endNight
28%7%15%27%15%4
1496
June1st to 15thNight
24%6%12%23%24%7%
1440
16th to endNight
13%36%22%36%18%
1440
July1st to 15thNight
7%3416%31%36%
1360
16th to endNight
7%1312%27%46%
1477
August1st to 15thNight
9%2419%29%33%
1611
16th to endNight
6%1317%35%36%
1896
September1st to 15thNight
6%2414%35%36%
1800
16th to endNight
12%38%23%28%23%
1850
October1st to 15thNight
21%49%26%27%10%
1980
16th to endNight
20%6%15%27%20%8%
2112
November1st to 15thNight
33%9%16%24%11%4
2271
16th to endNight
32%8%16%22%15%4
2496
December1st to 15thNight
39%9%12%21%16%
2520
16th to endNight
43%10%10%18%15%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
30%8%26%35%
60
16th to endDay
12%19%17%25%13%10%
241
February1st to 15thDay
11%20%19%28%17%1
236
16th to endDay
15%21%21%30%10%
233
March1st to 15thDay
17%24%28%16%8%4
270
16th to endDay
13%29%28%19%9%
288
April1st to 15thDay
14%23%30%23%5%2
269
16th to endDay
10%24%30%21%11%1
270
May1st to 15thDay
8%17%34%26%10%2
288
16th to endDay
12%12%22%23%21%8%
330
June1st to 15thDay
7%16%32%24%12%6%
315
16th to endDay
19%32%31%19%6%
315
July1st to 15thDay
1329%35%20%8%
305
16th to endDay
426%41%17%8%
327
August1st to 15thDay
15%30%32%19%10%
315
16th to endDay
15%33%27%18%13%
332
September1st to 15thDay
26%20%40%21%8%
315
16th to endDay
5%10%27%28%23%3
276
October1st to 15thDay
7%16%25%26%17%6%
255
16th to endDay
10%12%29%27%15%4
272
November1st to 15thDay
9%5%15%29%32%8%
93
16th to endDay
47%36%26%20%3
63
December1st to 15thDay
18%13%31%31%5%
60
16th to endDay
6%10%26%39%17%
64
January1st to 15thNight
7%6%21%44%18%1
720
16th to endNight
9%5%25%37%20%2
768
February1st to 15thNight
7%7%25%39%18%
704
16th to endNight
10%9%21%42%14%1
632
March1st to 15thNight
9%10%24%34%18%2
720
16th to endNight
7%10%30%33%18%
768
April1st to 15thNight
8%7%26%40%16%
719
16th to endNight
7%8%22%38%18%4
720
May1st to 15thNight
5%425%39%23%1
459
16th to endNight
8%217%36%32%1
375
June1st to 15thNight
5%216%44%29%
360
16th to endNight
3112%43%39%
360
July1st to 15thNight
1239%55%2
340
16th to endNight
1238%54%2
442
August1st to 15thNight
2135%55%5%
538
16th to endNight
16%43%43%4
750
September1st to 15thNight
17%37%47%5%
720
16th to endNight
2311%36%39%7%
680
October1st to 15thNight
5%317%40%28%4
660
16th to endNight
6%216%39%29%5%
704
November1st to 15thNight
7%5%16%45%20%3
700
16th to endNight
5%7%25%38%20%2
720
December1st to 15thNight
11%7%21%41%15%2
720
16th to endNight
11%7%29%39%11%
768
Page generated at 2017-09-22 04:35:33. Version ac04

Copyright 2017 A. Danko


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