Predator Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Predator Bay clear sky chart from 2005-11-05 to 2018-02-13.

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
44%
15853
14%
48837
10%
15824
49%
15824
23%
32672

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
38%
972
11%
2910
8%
970
42%
970
18%
2090
January16th to endNight
39%
884
19%
2964
15%
884
47%
884
21%
1924
February1st to 15thNight
44%
748
14%
2574
13%
745
48%
745
18%
1732
February16th to endNight
41%
632
13%
1977
10%
632
45%
632
18%
1407
March1st to 15thNight
36%
720
14%
2115
9%
720
42%
720
21%
1485
March16th to endNight
34%
768
11%
2093
3%
768
39%
768
18%
1552
April1st to 15thNight
35%
626
11%
1706
5%
626
38%
626
19%
1268
April16th to endNight
38%
540
12%
1620
8%
540
43%
540
20%
1140
May1st to 15thNight
43%
428
11%
1428
10%
428
48%
428
21%
934
May16th to endNight
43%
374
5%
1309
3%
374
44%
374
15%
934
June1st to 15thNight
44%
360
1%
1260
0%
360
45%
360
17%
880
June16th to endNight
55%
360
1%
1260
0%
360
55%
360
23%
797
July1st to 15thNight
60%
340
2%
1190
0%
340
61%
340
28%
699
July16th to endNight
63%
376
11%
1283
12%
354
68%
354
32%
698
August1st to 15thNight
64%
406
12%
1478
13%
404
67%
404
26%
863
August16th to endNight
64%
573
22%
1719
19%
573
66%
573
42%
917
September1st to 15thNight
58%
662
18%
1814
13%
662
59%
662
36%
1110
September16th to endNight
55%
716
22%
1980
15%
716
60%
716
39%
1181
October1st to 15thNight
45%
720
17%
2117
11%
720
51%
720
23%
1439
October16th to endNight
46%
768
21%
2496
14%
768
56%
768
26%
1553
November1st to 15thNight
38%
890
18%
2600
12%
890
45%
890
23%
1745
November16th to endNight
37%
975
16%
2899
9%
975
44%
975
23%
1944
December1st to 15thNight
42%
975
14%
2925
10%
975
45%
975
19%
2107
December16th to endNight
40%
1040
16%
3120
10%
1040
45%
1040
18%
2273

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
10%8%36%5%35%5%6%8%35%
49237
Night
8%9%46%6%35%5%6%8%37%
48988
Cloud CoverDay
10%8%36%5%35%5%6%8%35%
49238
Night
7%9%47%6%35%5%6%8%36%
48991
TransparencyDay
44%7%15%21%8%1
48892
Night
43%7%15%22%9%1
48837
SeeingDay
14%7%26%29%16%5%
6391
Night
12%5%26%37%16%2
15862

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
7%10%47%6%35%45%8%35%
1358
16th to endDay
5%11%38%7%345%7%8%33%
1624
February1st to 15thDay
6%11%5%7%6%46%5%6%7%31%
1552
16th to endDay
412%7%8%6%45%5%7%7%28%
1495
March1st to 15thDay
410%5%8%8%35%6%6%8%32%
1845
16th to endDay
9%15%5%7%7%35%5%6%8%25%
2129
April1st to 15thDay
11%15%5%7%6%35%5%5%7%26%
2242
16th to endDay
14%10%47%6%25%5%5%8%29%
2340
May1st to 15thDay
12%8%36%5%35%5%6%7%35%
2520
16th to endDay
22%7%26%6%25%5%6%7%26%
2802
June1st to 15thDay
20%7%36%6%35%5%5%8%27%
2700
16th to endDay
14%5%35%5%35%6%6%9%34%
2700
July1st to 15thDay
10%424435%6%6%9%42%
2700
16th to endDay
6%323435%5%7%9%47%
2797
August1st to 15thDay
12%4244345%7%9%41%
2472
16th to endDay
9%3133345%5%9%49%
2483
September1st to 15thDay
14%5%14423345%50%
2145
16th to endDay
9%5%25%43445%7%45%
1980
October1st to 15thDay
14%10%36%5%25%46%7%33%
1842
16th to endDay
7%8%46%6%25%5%7%8%36%
1728
November1st to 15thDay
9%10%47%6%25%5%48%34%
1574
16th to endDay
5%13%37%42346%9%38%
1388
December1st to 15thDay
410%5%9%8%5%8%5%5%6%30%
1365
16th to endDay
312%5%10%6%36%6%7%8%30%
1456
January1st to 15thNight
5%10%5%9%7%46%5%6%8%28%
2910
16th to endNight
5%10%48%6%35%5%7%8%35%
2964
February1st to 15thNight
6%10%47%6%36%5%5%7%35%
2563
16th to endNight
411%5%10%9%35%5%5%6%31%
1977
March1st to 15thNight
49%5%7%7%45%7%5%10%31%
2115
16th to endNight
7%12%6%8%6%35%5%7%8%27%
2090
April1st to 15thNight
13%12%5%7%6%35%446%30%
1706
16th to endNight
13%10%46%5%25%45%7%33%
1620
May1st to 15thNight
9%10%37%4245%5%8%38%
1427
16th to endNight
19%7%35%435%5%6%7%30%
1309
June1st to 15thNight
16%7%36%6%36%5%6%7%30%
1260
16th to endNight
11%415%446%6%7%9%38%
1260
July1st to 15thNight
7%42443446%8%48%
1260
16th to endNight
6%41432346%7%53%
1371
August1st to 15thNight
9%5%144245%6%9%45%
1486
16th to endNight
9%313214349%56%
1719
September1st to 15thNight
13%6%1331335%7%50%
1814
16th to endNight
10%41332446%7%51%
1980
October1st to 15thNight
12%9%26%5%3445%7%38%
2117
16th to endNight
8%8%245%25%5%6%8%41%
2496
November1st to 15thNight
6%10%45%5%35%46%6%39%
2600
16th to endNight
5%11%5%7%6%3446%8%36%
2899
December1st to 15thNight
49%5%9%8%46%5%5%7%31%
2925
16th to endNight
411%410%9%46%5%7%7%29%
3120

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
7%11%47%6%35%45%8%34%
1358
16th to endDay
5%10%48%6%45%5%7%8%32%
1624
February1st to 15thDay
7%10%5%7%6%37%6%6%7%31%
1552
16th to endDay
5%12%7%8%6%5%5%5%7%6%28%
1495
March1st to 15thDay
410%5%8%8%35%6%6%8%32%
1845
16th to endDay
9%14%5%7%7%35%5%6%8%25%
2130
April1st to 15thDay
11%14%5%7%6%36%5%5%8%25%
2242
16th to endDay
14%10%48%5%345%6%7%29%
2340
May1st to 15thDay
11%9%46%435%5%5%8%34%
2520
16th to endDay
21%7%26%5%36%5%6%7%26%
2802
June1st to 15thDay
19%7%36%5%45%5%5%7%28%
2700
16th to endDay
13%5%35%5%35%6%6%9%34%
2700
July1st to 15thDay
9%424435%6%7%8%42%
2700
16th to endDay
5%414435%5%8%9%47%
2797
August1st to 15thDay
12%4244345%7%8%42%
2472
16th to endDay
9%3134335%6%9%49%
2483
September1st to 15thDay
13%5%24323337%49%
2145
16th to endDay
9%5%25%5%3445%8%45%
1980
October1st to 15thDay
13%10%27%5%3445%8%33%
1842
16th to endDay
6%8%47%6%25%5%8%8%36%
1728
November1st to 15thDay
8%10%5%8%6%35%5%5%7%33%
1574
16th to endDay
6%12%47%5%2437%8%37%
1388
December1st to 15thDay
410%5%10%8%5%8%5%5%6%29%
1365
16th to endDay
411%5%10%8%35%6%7%9%28%
1456
January1st to 15thNight
5%11%5%9%8%46%5%7%9%27%
2910
16th to endNight
5%10%48%6%25%5%7%9%34%
2964
February1st to 15thNight
6%10%47%6%46%5%5%7%35%
2563
16th to endNight
410%5%10%9%45%5%5%7%29%
1977
March1st to 15thNight
410%5%7%7%36%6%6%9%30%
2115
16th to endNight
6%13%5%8%6%36%6%6%8%27%
2093
April1st to 15thNight
12%12%47%7%35%447%29%
1706
16th to endNight
12%10%37%43445%8%33%
1620
May1st to 15thNight
9%9%46%5%236%5%8%37%
1427
16th to endNight
19%7%36%5%36%46%7%29%
1309
June1st to 15thNight
16%8%36%5%45%6%5%8%30%
1260
16th to endNight
10%425%5%36%6%7%9%38%
1260
July1st to 15thNight
6%4245%25%5%6%8%47%
1260
16th to endNight
5%4243245%6%9%52%
1371
August1st to 15thNight
8%5%145%345%7%9%44%
1486
16th to endNight
8%31321345%8%56%
1719
September1st to 15thNight
12%6%12323347%49%
1814
16th to endNight
9%42332345%8%51%
1980
October1st to 15thNight
11%9%35%6%3347%6%37%
2117
16th to endNight
8%8%25%4246%6%8%40%
2496
November1st to 15thNight
6%10%46%6%25%5%5%7%38%
2600
16th to endNight
5%11%5%8%6%3446%7%36%
2899
December1st to 15thNight
49%5%10%9%46%6%6%7%30%
2925
16th to endNight
311%5%10%9%46%6%6%7%28%
3120

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
46%6%15%23%6%2
1358
16th to endDay
45%7%14%18%10%3
1624
February1st to 15thDay
48%8%15%17%8%2
1552
16th to endDay
52%7%13%17%8%
1495
March1st to 15thDay
47%9%17%18%6%
1845
16th to endDay
54%7%13%19%5%
2130
April1st to 15thDay
55%6%14%15%6%
2242
16th to endDay
51%7%13%17%8%1
2340
May1st to 15thDay
45%7%14%21%10%
2520
16th to endDay
54%7%13%18%5%
2807
June1st to 15thDay
53%7%13%17%6%1
2700
16th to endDay
43%8%17%22%6%1
2700
July1st to 15thDay
35%9%19%25%8%1
2541
16th to endDay
29%10%18%27%11%1
2622
August1st to 15thDay
36%8%22%24%6%1
2455
16th to endDay
29%8%18%30%12%1
2483
September1st to 15thDay
35%5%13%24%17%4
2145
16th to endDay
36%6%12%30%11%3
1980
October1st to 15thDay
48%6%14%20%9%
1842
16th to endDay
40%7%15%26%8%1
1728
November1st to 15thDay
48%7%13%21%7%1
1574
16th to endDay
42%5%17%23%8%2
1388
December1st to 15thDay
53%6%13%17%7%1
1365
16th to endDay
48%6%15%18%9%1
1456
January1st to 15thNight
51%6%16%18%5%2
2910
16th to endNight
43%6%15%19%12%3
2964
February1st to 15thNight
46%6%13%21%10%1
2574
16th to endNight
50%6%11%19%10%
1977
March1st to 15thNight
45%8%17%21%5%
2115
16th to endNight
51%7%14%18%7%
2093
April1st to 15thNight
54%5%12%17%9%
1706
16th to endNight
47%7%14%22%6%1
1620
May1st to 15thNight
42%8%13%23%11%
1428
16th to endNight
51%7%15%17%5%1
1309
June1st to 15thNight
50%7%14%18%8%
1260
16th to endNight
37%10%19%23%8%
1260
July1st to 15thNight
33%8%19%28%9%
1190
16th to endNight
27%9%16%32%11%1
1283
August1st to 15thNight
32%10%19%27%9%
1478
16th to endNight
25%417%32%16%3
1719
September1st to 15thNight
33%5%14%23%18%5%
1814
16th to endNight
30%5%17%27%14%4
1980
October1st to 15thNight
44%7%13%21%11%1
2117
16th to endNight
37%8%17%25%10%
2496
November1st to 15thNight
42%6%13%22%12%
2600
16th to endNight
44%6%18%19%8%2
2899
December1st to 15thNight
50%7%13%20%6%1
2925
16th to endNight
51%7%11%21%7%
3120

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%311%32%20%20%
90
16th to endDay
8%6%16%42%17%8%
96
February1st to 15thDay
12%8%26%33%16%3
96
16th to endDay
10%7%25%40%16%
154
March1st to 15thDay
8%14%45%24%6%1
270
16th to endDay
12%17%37%21%9%2
288
April1st to 15thDay
18%14%30%26%9%1
269
16th to endDay
21%12%27%25%10%2
270
May1st to 15thDay
16%7%27%25%16%5%
369
16th to endDay
23%5%17%26%21%5%
517
June1st to 15thDay
20%7%24%30%14%2
495
16th to endDay
14%427%32%15%4
495
July1st to 15thDay
11%420%30%26%6%
475
16th to endDay
7%5%28%33%21%4
466
August1st to 15thDay
14%323%32%17%8%
315
16th to endDay
9%6%25%31%17%9%
332
September1st to 15thDay
18%6%25%28%15%5%
315
16th to endDay
9%11%24%31%14%7%
315
October1st to 15thDay
20%7%24%26%19%1
204
16th to endDay
9%8%29%30%17%4
144
November1st to 15thDay
20%8%23%32%8%5%
135
16th to endDay
7%438%22%13%13%
95
December1st to 15thDay
4331%35%17%7%
90
16th to endDay
13%322%35%18%6%
96
January1st to 15thNight
10%8%27%38%12%2
975
16th to endNight
10%7%30%38%10%2
884
February1st to 15thNight
11%6%23%37%16%3
752
16th to endNight
10%327%38%17%2
632
March1st to 15thNight
8%6%36%33%12%2
720
16th to endNight
14%6%29%35%12%1
768
April1st to 15thNight
16%6%30%30%13%1
626
16th to endNight
19%5%26%34%14%
540
May1st to 15thNight
14%7%25%33%18%1
429
16th to endNight
23%321%30%20%
375
June1st to 15thNight
19%421%37%16%1
360
16th to endNight
14%218%40%22%1
360
July1st to 15thNight
9%216%39%29%2
340
16th to endNight
8%119%46%22%2
376
August1st to 15thNight
11%213%35%33%3
406
16th to endNight
9%218%42%26%
573
September1st to 15thNight
16%318%32%25%3
662
16th to endNight
11%224%39%18%3
716
October1st to 15thNight
17%323%36%16%3
720
16th to endNight
12%428%39%13%1
768
November1st to 15thNight
11%8%32%34%10%2
890
16th to endNight
11%6%33%35%10%2
975
December1st to 15thNight
9%5%28%39%14%2
975
16th to endNight
9%5%27%42%11%3
1040
Page generated at 2018-02-13 17:46:09. Version ac04

Copyright 2018 A. Danko


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