Pelican Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pelican Point clear sky chart from 2005-11-05 to 2017-09-23.

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%
15247
11%
46845
8%
15221
45%
15221
19%
33137

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
33%
895
8%
2685
5%
895
36%
895
14%
2031
January16th to endNight
34%
894
15%
2814
8%
894
42%
894
17%
1998
February1st to 15thNight
40%
697
9%
2406
8%
696
44%
696
15%
1692
February16th to endNight
43%
632
13%
2025
12%
632
47%
632
18%
1440
March1st to 15thNight
40%
720
13%
2097
8%
720
45%
720
19%
1532
March16th to endNight
35%
768
8%
2109
3%
767
38%
767
15%
1658
April1st to 15thNight
37%
592
11%
1675
5%
592
41%
592
18%
1238
April16th to endNight
41%
540
12%
1620
10%
540
44%
540
20%
1126
May1st to 15thNight
44%
419
11%
1350
9%
419
47%
419
19%
939
May16th to endNight
43%
374
2%
1309
2%
374
43%
374
14%
939
June1st to 15thNight
43%
360
0%
1260
0%
360
43%
360
14%
918
June16th to endNight
51%
360
0%
1260
0%
360
51%
360
18%
854
July1st to 15thNight
60%
340
0%
1190
0%
340
60%
340
22%
770
July16th to endNight
61%
376
5%
1239
5%
354
62%
354
25%
753
August1st to 15thNight
62%
402
8%
1436
9%
400
64%
400
21%
915
August16th to endNight
59%
573
14%
1719
13%
573
60%
573
31%
1065
September1st to 15thNight
56%
615
16%
1781
12%
615
57%
615
29%
1129
September16th to endNight
53%
688
20%
1903
13%
688
57%
688
34%
1179
October1st to 15thNight
40%
660
15%
1955
9%
660
46%
660
21%
1365
October16th to endNight
43%
707
15%
2291
10%
707
49%
707
19%
1567
November1st to 15thNight
37%
875
16%
2450
10%
875
42%
875
20%
1759
November16th to endNight
29%
900
11%
2691
7%
900
33%
900
15%
2038
December1st to 15thNight
28%
900
9%
2700
5%
900
32%
900
13%
2106
December16th to endNight
36%
960
13%
2880
8%
960
42%
960
17%
2126

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%8%37%6%35%5%6%8%33%
48099
Night
10%9%47%6%35%5%6%8%31%
46999
TransparencyDay
48%8%16%20%5%
47749
Night
48%7%15%20%7%1
46853
SeeingDay
15%5%23%30%20%5%
6113
Night
14%426%35%16%2
15261

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
6%13%7%7%9%5%5%447%26%
1253
16th to endDay
7%11%5%8%7%36%6%6%7%29%
1422
February1st to 15thDay
10%11%49%7%45%35%9%28%
1452
16th to endDay
8%11%6%10%8%37%5%6%7%24%
1448
March1st to 15thDay
9%11%48%7%5%7%6%6%7%26%
1863
16th to endDay
12%13%5%8%6%35%5%7%7%24%
2111
April1st to 15thDay
13%11%48%7%45%5%5%7%27%
2273
16th to endDay
15%10%36%6%35%46%8%30%
2340
May1st to 15thDay
9%9%37%5%36%6%6%7%34%
2600
16th to endDay
20%6%36%5%445%6%6%29%
2802
June1st to 15thDay
18%7%46%6%35%5%6%7%28%
2700
16th to endDay
13%6%35%6%35%5%7%9%32%
2700
July1st to 15thDay
11%4245%36%5%6%9%39%
2700
16th to endDay
10%424425%5%5%8%45%
2846
August1st to 15thDay
13%5%25%6%35%5%6%9%38%
2516
16th to endDay
9%5%24435%5%6%9%44%
2483
September1st to 15thDay
15%6%15%5%24346%42%
2177
16th to endDay
10%5%2443336%9%45%
1893
October1st to 15thDay
12%9%47%5%35%445%37%
1672
16th to endDay
11%11%45%5%345%6%7%34%
1570
November1st to 15thDay
9%12%7%9%5%35%5%5%8%28%
1408
16th to endDay
8%10%411%9%36%5%5%7%27%
1266
December1st to 15thDay
9%14%7%13%9%6%7%45%5%18%
1260
16th to endDay
7%12%411%9%46%5%6%7%23%
1344
January1st to 15thNight
7%11%6%10%9%5%6%6%6%8%22%
2685
16th to endNight
7%12%5%7%6%45%6%5%7%31%
2814
February1st to 15thNight
6%9%5%9%8%45%5%6%7%30%
2400
16th to endNight
8%12%6%6%6%35%5%6%8%29%
2025
March1st to 15thNight
6%10%5%7%7%47%6%7%9%27%
2097
16th to endNight
10%12%6%9%7%46%6%6%8%21%
2109
April1st to 15thNight
12%10%47%6%35%6%6%8%27%
1675
16th to endNight
15%9%45%5%25%45%8%33%
1620
May1st to 15thNight
12%10%46%5%4445%8%33%
1349
16th to endNight
22%7%35%5%3446%7%28%
1309
June1st to 15thNight
18%6%37%5%5%6%5%7%7%27%
1260
16th to endNight
10%6%36%6%46%6%7%8%33%
1260
July1st to 15thNight
10%4245%35%5%7%12%37%
1260
16th to endNight
9%325%435%5%6%9%43%
1323
August1st to 15thNight
11%425%4347%6%9%39%
1443
16th to endNight
7%425%5%446%6%8%44%
1719
September1st to 15thNight
13%425%5%24347%46%
1781
16th to endNight
11%6%2341345%8%48%
1903
October1st to 15thNight
12%9%38%5%3445%7%34%
1955
16th to endNight
9%9%36%6%36%6%6%8%33%
2291
November1st to 15thNight
9%11%5%6%5%35%5%6%8%32%
2450
16th to endNight
8%12%6%10%8%36%5%5%6%27%
2691
December1st to 15thNight
9%13%6%11%9%45%447%23%
2700
16th to endNight
5%11%5%10%8%5%6%5%5%9%25%
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
56%7%12%16%5%
1253
16th to endDay
51%7%13%16%8%1
1422
February1st to 15thDay
52%7%15%16%6%
1452
16th to endDay
56%6%12%16%6%
1448
March1st to 15thDay
54%9%14%16%4
1863
16th to endDay
56%8%14%16%3
2112
April1st to 15thDay
54%7%13%16%6%
2273
16th to endDay
51%7%14%16%7%1
2340
May1st to 15thDay
46%8%13%22%9%
2600
16th to endDay
52%7%13%18%6%
2807
June1st to 15thDay
53%9%13%19%3
2700
16th to endDay
45%10%20%20%3
2700
July1st to 15thDay
40%9%22%23%4
2541
16th to endDay
37%10%23%26%3
2667
August1st to 15thDay
41%10%25%19%4
2498
16th to endDay
33%8%23%25%7%
2483
September1st to 15thDay
41%5%17%24%8%1
2177
16th to endDay
35%7%17%29%8%2
1893
October1st to 15thDay
49%5%17%20%7%
1672
16th to endDay
46%8%13%24%6%
1570
November1st to 15thDay
53%6%14%19%5%
1408
16th to endDay
54%8%16%13%6%1
1266
December1st to 15thDay
67%5%10%14%2
1260
16th to endDay
56%6%12%17%5%
1344
January1st to 15thNight
56%6%16%13%41
2685
16th to endNight
50%6%13%18%8%2
2814
February1st to 15thNight
51%6%15%18%7%
2411
16th to endNight
50%7%14%16%10%1
2025
March1st to 15thNight
49%9%15%19%6%
2097
16th to endNight
58%7%12%15%5%
2112
April1st to 15thNight
51%8%13%17%7%1
1675
16th to endNight
48%6%13%21%7%2
1620
May1st to 15thNight
48%6%9%22%10%1
1350
16th to endNight
53%7%10%19%6%1
1309
June1st to 15thNight
52%9%12%19%5%
1260
16th to endNight
45%9%20%18%5%
1260
July1st to 15thNight
37%12%20%24%5%
1190
16th to endNight
35%9%23%25%5%
1239
August1st to 15thNight
38%11%21%22%5%
1436
16th to endNight
34%8%20%27%8%1
1719
September1st to 15thNight
37%6%13%25%12%3
1781
16th to endNight
33%7%14%27%13%3
1903
October1st to 15thNight
47%7%15%21%8%
1955
16th to endNight
45%8%16%24%5%
2291
November1st to 15thNight
48%7%12%22%6%1
2450
16th to endNight
55%7%13%14%7%1
2691
December1st to 15thNight
61%6%12%16%3
2700
16th to endNight
54%6%14%19%5%
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
6%123%43%18%6%
60
16th to endDay
6%325%26%25%14%
64
February1st to 15thDay
21%220%36%14%4
69
16th to endDay
16%323%28%24%2
107
March1st to 15thDay
16%434%31%11%1
270
16th to endDay
19%431%33%9%1
288
April1st to 15thDay
16%13%26%28%13%1
269
16th to endDay
24%8%25%25%14%2
270
May1st to 15thDay
13%7%24%30%19%5%
438
16th to endDay
20%419%27%19%7%
517
June1st to 15thDay
19%5%23%30%15%5%
495
16th to endDay
14%5%24%29%20%6%
495
July1st to 15thDay
11%213%35%29%6%
475
16th to endDay
11%5%19%32%26%5%
515
August1st to 15thDay
11%216%29%27%11%
353
16th to endDay
11%420%31%27%4
332
September1st to 15thDay
18%324%27%17%6%
315
16th to endDay
15%9%22%26%20%5%
284
October1st to 15thDay
21%6%26%23%19%3
126
16th to endDay
17%323%30%20%4
96
November1st to 15thDay
17%328%35%12%2
90
16th to endDay
11%8%27%18%24%9%
61
December1st to 15thDay
6%35%26%28%3
60
16th to endDay
12%423%32%21%4
64
January1st to 15thNight
13%8%30%32%14%1
900
16th to endNight
13%7%31%33%11%2
894
February1st to 15thNight
10%6%25%34%19%3
704
16th to endNight
13%5%24%35%18%3
632
March1st to 15thNight
10%430%37%15%2
720
16th to endNight
16%327%36%14%2
768
April1st to 15thNight
15%430%32%14%2
592
16th to endNight
21%422%35%14%1
540
May1st to 15thNight
15%5%24%37%15%2
420
16th to endNight
24%5%18%26%21%3
375
June1st to 15thNight
23%417%33%17%3
360
16th to endNight
14%221%33%27%1
360
July1st to 15thNight
12%116%43%25%
340
16th to endNight
10%218%42%24%1
376
August1st to 15thNight
13%113%34%32%4
402
16th to endNight
9%318%40%27%1
573
September1st to 15thNight
14%119%39%22%2
615
16th to endNight
13%423%39%16%1
688
October1st to 15thNight
17%230%31%15%2
660
16th to endNight
14%428%39%13%
707
November1st to 15thNight
14%6%31%35%10%1
875
16th to endNight
13%6%33%31%11%2
900
December1st to 15thNight
15%7%31%29%14%2
900
16th to endNight
12%331%32%16%3
960
Page generated at 2017-09-24 07:15:55. Version ac04

Copyright 2017 A. Danko


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