AllSky Camera - Tatla Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the AllSky Camera - Tatla Lake clear sky chart from 2005-11-05 to 2017-09-10.

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
41%
14344
10%
46683
7%
14315
46%
14315
19%
32015

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
34%
750
9%
2686
5%
746
40%
746
12%
1963
January16th to endNight
38%
800
12%
2880
8%
800
44%
800
17%
1972
February1st to 15thNight
36%
699
10%
2310
5%
699
43%
699
17%
1636
February16th to endNight
45%
632
14%
2053
12%
632
49%
632
20%
1386
March1st to 15thNight
29%
720
13%
2076
5%
720
36%
720
20%
1446
March16th to endNight
42%
768
12%
2096
7%
767
45%
767
24%
1435
April1st to 15thNight
42%
635
10%
1715
5%
635
45%
635
20%
1234
April16th to endNight
39%
501
9%
1581
7%
501
43%
501
18%
1136
May1st to 15thNight
45%
359
7%
1434
8%
359
48%
359
17%
933
May16th to endNight
42%
374
3%
1309
1%
374
43%
374
13%
976
June1st to 15thNight
43%
360
0%
1260
0%
360
43%
360
17%
858
June16th to endNight
48%
360
0%
1260
0%
360
48%
360
18%
849
July1st to 15thNight
55%
340
1%
1190
0%
340
55%
340
24%
716
July16th to endNight
56%
376
7%
1239
6%
354
60%
354
29%
715
August1st to 15thNight
70%
420
12%
1452
16%
418
71%
418
26%
869
August16th to endNight
55%
573
14%
1719
10%
573
59%
573
26%
1123
September1st to 15thNight
61%
676
18%
1726
10%
676
64%
676
37%
1084
September16th to endNight
44%
656
16%
1825
9%
656
49%
656
25%
1225
October1st to 15thNight
42%
660
12%
1980
7%
660
48%
660
21%
1349
October16th to endNight
36%
704
12%
2279
6%
704
44%
704
17%
1608
November1st to 15thNight
31%
700
11%
2450
6%
700
39%
700
16%
1686
November16th to endNight
33%
731
11%
2583
6%
731
41%
731
16%
1803
December1st to 15thNight
34%
750
9%
2700
6%
750
39%
750
13%
1968
December16th to endNight
30%
800
12%
2880
5%
800
39%
800
14%
2045

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
5%7%37%7%46%6%7%9%33%
47981
Night
47%36%6%46%6%7%9%36%
46831
TransparencyDay
45%11%17%18%6%
47629
Night
43%11%19%19%6%
46687
SeeingDay
13%17%31%24%10%2
6371
Night
8%7%32%33%15%1
14354

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
37%38%11%6%7%6%9%10%25%
1253
16th to endDay
16%25%5%37%7%9%13%35%
1344
February1st to 15thDay
28%37%6%5%7%7%8%12%29%
1550
16th to endDay
16%49%6%38%7%8%9%33%
1421
March1st to 15thDay
15%37%7%47%7%9%11%34%
1882
16th to endDay
17%39%8%5%8%7%9%10%28%
2124
April1st to 15thDay
39%5%9%9%47%7%7%9%26%
2230
16th to endDay
412%5%9%8%47%7%7%8%24%
2379
May1st to 15thDay
5%9%48%7%5%7%7%7%8%28%
2517
16th to endDay
12%10%48%6%47%6%7%7%24%
2804
June1st to 15thDay
11%8%38%7%46%6%6%8%28%
2700
16th to endDay
10%7%36%8%47%5%8%8%28%
2700
July1st to 15thDay
8%5%35%5%36%5%6%7%42%
2700
16th to endDay
5%5%36%6%46%5%5%7%43%
2846
August1st to 15thDay
5%5%25%6%45%5%5%7%45%
2496
16th to endDay
46%26%6%46%7%7%8%38%
2483
September1st to 15thDay
7%6%25%5%34448%47%
2120
16th to endDay
5%5%25%6%35%7%6%11%41%
1802
October1st to 15thDay
6%7%36%7%46%6%7%8%35%
1650
16th to endDay
36%37%7%46%6%7%11%34%
1591
November1st to 15thDay
45%35%6%37%6%9%11%35%
1408
16th to endDay
27%47%7%37%8%7%8%35%
1377
December1st to 15thDay
26%48%7%46%8%8%9%32%
1260
16th to endDay
6%39%6%38%7%9%14%29%
1344
January1st to 15thNight
27%38%8%5%10%8%8%10%26%
2686
16th to endNight
26%46%6%5%7%7%8%12%32%
2880
February1st to 15thNight
38%47%6%5%6%7%7%9%33%
2298
16th to endNight
18%5%8%7%46%5%7%8%36%
2053
March1st to 15thNight
16%38%6%45%7%8%11%36%
2076
16th to endNight
25%26%5%46%8%9%13%35%
2096
April1st to 15thNight
39%36%7%36%6%7%9%33%
1715
16th to endNight
49%48%6%36%5%6%10%33%
1581
May1st to 15thNight
5%8%46%6%35%7%6%11%35%
1433
16th to endNight
14%7%26%7%46%6%7%8%28%
1309
June1st to 15thNight
12%436%6%26%6%8%9%34%
1260
16th to endNight
10%6%35%5%346%6%8%39%
1260
July1st to 15thNight
7%313447%5%6%8%46%
1260
16th to endNight
5%424426%46%9%49%
1323
August1st to 15thNight
6%4335%25%5%6%8%48%
1459
16th to endNight
6%5%35%6%35%6%6%8%43%
1719
September1st to 15thNight
7%5%2442336%6%52%
1726
16th to endNight
6%6%36%5%35%5%7%7%43%
1825
October1st to 15thNight
5%9%25%5%35%46%9%40%
1980
16th to endNight
49%37%5%46%5%7%9%35%
2279
November1st to 15thNight
27%37%6%46%7%8%10%33%
2450
16th to endNight
28%5%8%6%46%6%6%9%34%
2583
December1st to 15thNight
39%5%7%7%48%7%7%9%28%
2700
16th to endNight
16%49%8%48%7%9%10%29%
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
52%11%16%15%3
1253
16th to endDay
37%13%22%18%6%2
1344
February1st to 15thDay
46%13%18%15%5%
1550
16th to endDay
45%10%16%20%7%
1421
March1st to 15thDay
40%11%20%20%7%
1882
16th to endDay
47%11%19%17%4
2124
April1st to 15thDay
52%11%15%14%6%
2230
16th to endDay
56%11%14%12%4
2379
May1st to 15thDay
52%10%15%14%6%
2517
16th to endDay
58%10%13%13%3
2808
June1st to 15thDay
51%10%16%15%5%1
2700
16th to endDay
51%10%14%16%5%
2700
July1st to 15thDay
40%9%14%22%11%1
2541
16th to endDay
37%9%19%23%10%
2667
August1st to 15thDay
34%10%20%25%7%
2478
16th to endDay
39%11%20%19%6%1
2483
September1st to 15thDay
35%7%19%25%10%1
2120
16th to endDay
36%11%18%24%7%1
1802
October1st to 15thDay
45%9%19%20%5%
1650
16th to endDay
42%12%20%19%4
1591
November1st to 15thDay
39%13%19%22%4
1408
16th to endDay
43%11%18%18%7%1
1377
December1st to 15thDay
46%12%19%17%3
1260
16th to endDay
42%12%18%18%6%
1344
January1st to 15thNight
51%10%17%16%3
2686
16th to endNight
43%12%20%15%6%2
2880
February1st to 15thNight
46%10%19%15%8%
2310
16th to endNight
45%7%16%24%5%
2053
March1st to 15thNight
40%12%19%20%6%
2076
16th to endNight
36%13%23%20%5%
2100
April1st to 15thNight
44%11%19%18%5%
1715
16th to endNight
48%10%19%17%4
1581
May1st to 15thNight
42%10%22%16%6%
1434
16th to endNight
52%12%17%14%3
1309
June1st to 15thNight
43%11%17%18%6%1
1260
16th to endNight
41%12%16%21%6%
1260
July1st to 15thNight
33%11%20%21%11%1
1190
16th to endNight
32%8%23%26%9%
1239
August1st to 15thNight
32%10%19%28%7%
1452
16th to endNight
36%11%20%24%5%1
1719
September1st to 15thNight
31%7%18%29%11%1
1726
16th to endNight
38%9%19%22%7%1
1825
October1st to 15thNight
39%12%19%22%6%
1980
16th to endNight
44%12%19%20%3
2279
November1st to 15thNight
44%11%20%19%4
2450
16th to endNight
45%11%18%16%5%2
2583
December1st to 15thNight
50%12%17%16%3
2700
16th to endNight
47%11%17%16%6%
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
316%36%28%15%
60
16th to endDay
328%37%26%4
64
February1st to 15thDay
8%13%37%30%8%1
233
16th to endDay
9%17%35%24%12%
211
March1st to 15thDay
11%31%34%16%4
263
16th to endDay
11%25%34%21%5%1
288
April1st to 15thDay
16%23%30%18%8%2
269
16th to endDay
19%27%27%19%4
270
May1st to 15thDay
15%21%28%25%7%1
294
16th to endDay
20%16%28%20%10%3
518
June1st to 15thDay
17%23%30%19%8%1
495
16th to endDay
15%18%33%20%10%2
495
July1st to 15thDay
12%16%32%27%8%2
475
16th to endDay
9%14%30%30%12%2
515
August1st to 15thDay
9%6%25%31%20%7%
354
16th to endDay
10%16%28%31%10%2
332
September1st to 15thDay
13%11%28%25%15%4
294
16th to endDay
12%18%30%26%10%1
255
October1st to 15thDay
14%18%32%19%12%2
255
16th to endDay
10%13%40%20%12%2
187
November1st to 15thDay
316%40%35%5%
60
16th to endDay
8%323%33%15%16%
60
December1st to 15thDay
8%330%25%20%13%
60
16th to endDay
7%6%34%26%18%6%
64
January1st to 15thNight
7%8%36%32%12%2
750
16th to endNight
6%8%36%33%12%2
800
February1st to 15thNight
7%7%36%31%15%1
707
16th to endNight
6%6%30%39%15%2
632
March1st to 15thNight
311%47%30%5%
720
16th to endNight
49%34%33%16%1
768
April1st to 15thNight
8%8%28%38%15%
635
16th to endNight
7%7%38%34%10%
501
May1st to 15thNight
8%6%30%39%15%
360
16th to endNight
18%5%24%37%13%1
375
June1st to 15thNight
12%7%30%36%11%
360
16th to endNight
13%6%25%38%16%
360
July1st to 15thNight
10%5%24%40%18%
340
16th to endNight
7%325%37%25%1
376
August1st to 15thNight
7%11%40%34%4
420
16th to endNight
9%422%35%26%1
573
September1st to 15thNight
11%418%31%29%5%
676
16th to endNight
11%9%28%28%18%3
656
October1st to 15thNight
11%8%28%32%16%1
660
16th to endNight
10%8%34%30%13%2
704
November1st to 15thNight
6%11%41%33%6%
700
16th to endNight
7%7%41%29%10%2
731
December1st to 15thNight
7%7%37%33%11%2
750
16th to endNight
6%6%41%30%12%2
800
Page generated at 2017-09-11 16:35:27. Version ac04

Copyright 2017 A. Danko


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