Presque Isle
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Presque Isle clear sky chart from 2005-11-05 to 2017-09-17.

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
30%
14705
12%
46792
7%
14674
36%
14674
16%
33859

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
20%
738
9%
2613
3%
734
29%
734
10%
2023
January16th to endNight
24%
768
12%
2688
5%
768
34%
768
13%
1957
February1st to 15thNight
24%
704
9%
2292
4%
701
31%
701
13%
1735
February16th to endNight
20%
631
11%
1940
4%
631
29%
631
12%
1504
March1st to 15thNight
23%
720
14%
2081
8%
720
31%
720
16%
1537
March16th to endNight
28%
768
16%
2112
8%
768
35%
768
21%
1537
April1st to 15thNight
24%
637
14%
1739
5%
637
30%
637
16%
1291
April16th to endNight
29%
540
17%
1620
8%
540
36%
540
19%
1136
May1st to 15thNight
30%
540
11%
1620
6%
540
35%
540
17%
1197
May16th to endNight
27%
417
9%
1361
5%
417
33%
417
15%
1002
June1st to 15thNight
38%
360
7%
1260
4%
360
43%
360
16%
902
June16th to endNight
39%
360
6%
1260
6%
360
41%
360
15%
905
July1st to 15thNight
45%
340
10%
1190
10%
340
49%
340
21%
805
July16th to endNight
48%
376
10%
1393
12%
354
52%
354
18%
920
August1st to 15thNight
50%
524
10%
1595
9%
522
52%
522
22%
1086
August16th to endNight
48%
573
19%
1719
11%
573
54%
573
29%
1079
September1st to 15thNight
40%
669
13%
1875
7%
669
44%
669
26%
1252
September16th to endNight
44%
665
20%
1836
13%
665
50%
665
31%
1155
October1st to 15thNight
34%
660
18%
1928
9%
660
42%
660
24%
1305
October16th to endNight
25%
704
12%
2239
5%
704
32%
704
16%
1631
November1st to 15thNight
27%
711
14%
2340
9%
711
35%
711
15%
1700
November16th to endNight
26%
750
12%
2520
7%
750
33%
750
12%
1876
December1st to 15thNight
20%
750
9%
2691
4%
750
27%
750
11%
2058
December16th to endNight
17%
800
9%
2880
4%
800
24%
800
9%
2266

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
18%8%36%6%35%45%6%29%
47997
Night
18%9%36%5%3445%6%31%
46952
TransparencyDay
53%6%12%18%8%
47675
Night
52%6%12%19%8%
46792
SeeingDay
24%8%27%24%12%2
6594
Night
23%8%31%28%8%
14706

By Month

Percentage Cloud Cover NE (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
13%14%6%8%6%445%5%6%24%
1322
16th to endDay
12%11%5%9%435%6%5%7%27%
1536
February1st to 15thDay
10%13%5%6%7%5%7%47%6%24%
1569
16th to endDay
16%11%5%9%6%36%5%5%6%25%
1533
March1st to 15thDay
18%11%46%6%35%447%28%
1867
16th to endDay
14%11%5%9%6%24435%32%
2112
April1st to 15thDay
20%9%46%6%35%45%5%28%
2206
16th to endDay
22%8%25%5%34445%33%
2340
May1st to 15thDay
24%7%26%5%24446%29%
2332
16th to endDay
24%7%36%6%35%446%27%
2763
June1st to 15thDay
23%8%26%6%35%5%5%7%24%
2700
16th to endDay
23%7%36%6%46%5%5%7%23%
2700
July1st to 15thDay
15%5%36%7%35%5%7%9%30%
2700
16th to endDay
16%6%36%6%45%6%7%8%29%
2678
August1st to 15thDay
16%5%36%6%36%5%6%8%31%
2343
16th to endDay
12%5%26%6%35%5%6%7%36%
2483
September1st to 15thDay
18%7%35%423337%41%
2082
16th to endDay
16%41442345%6%45%
1830
October1st to 15thDay
18%8%36%5%33436%35%
1702
16th to endDay
24%9%46%4235%46%27%
1631
November1st to 15thDay
20%9%36%5%35%5%5%5%29%
1518
16th to endDay
21%10%48%425%446%27%
1440
December1st to 15thDay
23%11%6%6%5%25%45%424%
1266
16th to endDay
22%13%5%8%6%24435%23%
1344
January1st to 15thNight
16%11%5%7%6%45%5%4425%
2613
16th to endNight
12%11%5%7%7%36%6%7%6%25%
2688
February1st to 15thNight
9%13%5%7%8%5%7%5%46%25%
2291
16th to endNight
15%15%48%6%35%34427%
1940
March1st to 15thNight
17%9%47%6%35%5%46%29%
2069
16th to endNight
15%10%5%8%5%33445%34%
2112
April1st to 15thNight
22%10%35%6%3434431%
1739
16th to endNight
25%8%25%324245%36%
1620
May1st to 15thNight
22%8%36%5%245%5%6%29%
1620
16th to endNight
23%8%36%5%2445%6%29%
1359
June1st to 15thNight
24%5%36%5%35%5%47%30%
1260
16th to endNight
19%7%35%5%35%45%7%31%
1260
July1st to 15thNight
17%6%35%6%345%47%35%
1260
16th to endNight
16%6%25%5%36%5%5%7%35%
1488
August1st to 15thNight
13%7%25%6%3445%7%37%
1605
16th to endNight
11%425%5%3445%8%44%
1719
September1st to 15thNight
15%6%245%2435%7%41%
1875
16th to endNight
13%4135%23445%50%
1836
October1st to 15thNight
19%6%24424347%39%
1928
16th to endNight
24%9%25%423346%32%
2239
November1st to 15thNight
21%9%35%5%35%346%31%
2340
16th to endNight
19%10%47%5%25%45%5%29%
2520
December1st to 15thNight
23%11%46%6%35%44427%
2691
16th to endNight
23%12%48%6%24445%22%
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
59%8%10%15%6%
1323
16th to endDay
53%6%13%17%8%
1536
February1st to 15thDay
56%6%13%15%6%
1572
16th to endDay
58%7%11%14%6%
1533
March1st to 15thDay
55%5%11%14%11%1
1878
16th to endDay
55%49%19%10%1
2112
April1st to 15thDay
55%5%10%16%9%2
2206
16th to endDay
52%410%17%12%3
2340
May1st to 15thDay
54%410%17%10%1
2332
16th to endDay
57%6%12%17%6%
2767
June1st to 15thDay
57%6%14%13%7%
2700
16th to endDay
58%8%12%14%7%
2700
July1st to 15thDay
46%9%17%19%7%
2541
16th to endDay
52%8%14%18%7%
2510
August1st to 15thDay
49%9%17%19%4
2329
16th to endDay
43%9%15%25%6%
2483
September1st to 15thDay
44%5%15%23%10%
2082
16th to endDay
39%5%12%28%12%
1830
October1st to 15thDay
51%413%23%7%
1702
16th to endDay
57%5%13%16%6%
1631
November1st to 15thDay
54%7%12%15%8%
1518
16th to endDay
57%6%13%16%4
1440
December1st to 15thDay
61%6%13%14%3
1266
16th to endDay
64%5%10%13%6%
1344
January1st to 15thNight
60%7%11%13%7%
2613
16th to endNight
54%7%11%18%7%
2688
February1st to 15thNight
57%6%12%17%5%
2292
16th to endNight
60%5%9%12%10%
1940
March1st to 15thNight
55%49%18%9%1
2081
16th to endNight
51%5%9%18%13%1
2112
April1st to 15thNight
54%5%9%14%12%2
1739
16th to endNight
51%37%18%16%2
1620
May1st to 15thNight
53%6%9%18%10%
1620
16th to endNight
54%7%12%16%8%
1361
June1st to 15thNight
53%6%13%19%6%1
1260
16th to endNight
52%8%13%17%8%
1260
July1st to 15thNight
46%7%16%22%7%
1190
16th to endNight
45%8%16%20%9%
1393
August1st to 15thNight
44%8%18%23%5%
1595
16th to endNight
36%8%17%30%7%
1719
September1st to 15thNight
42%6%12%27%10%1
1875
16th to endNight
35%6%15%29%12%
1836
October1st to 15thNight
44%6%12%26%10%
1928
16th to endNight
53%6%12%20%6%
2239
November1st to 15thNight
53%6%14%15%9%
2340
16th to endNight
55%8%12%16%6%
2520
December1st to 15thNight
60%6%12%17%2
2691
16th to endNight
63%6%10%14%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
11%23%25%33%6%
60
16th to endDay
20%445%15%12%1
64
February1st to 15thDay
16%10%30%31%10%
230
16th to endDay
23%12%30%24%8%
231
March1st to 15thDay
25%11%31%23%8%
270
16th to endDay
21%10%27%26%11%2
288
April1st to 15thDay
28%11%25%21%9%2
270
16th to endDay
25%10%27%16%14%5%
270
May1st to 15thDay
33%6%28%19%9%2
288
16th to endDay
28%12%28%22%7%
511
June1st to 15thDay
27%10%22%28%9%1
495
16th to endDay
25%6%31%23%11%1
495
July1st to 15thDay
18%5%26%29%18%1
475
16th to endDay
20%227%32%15%2
349
August1st to 15thDay
20%425%25%16%7%
313
16th to endDay
19%8%19%25%20%5%
332
September1st to 15thDay
21%6%26%25%14%5%
315
16th to endDay
21%6%26%23%15%7%
259
October1st to 15thDay
21%11%28%16%14%7%
234
16th to endDay
34%10%26%20%7%1
240
November1st to 15thDay
25%11%30%20%9%2
235
16th to endDay
27%12%26%22%10%
240
December1st to 15thDay
27%6%34%21%9%1
66
16th to endDay
28%17%35%15%3
64
January1st to 15thNight
22%12%36%24%4
738
16th to endNight
18%11%36%27%6%
768
February1st to 15thNight
16%9%40%27%6%
704
16th to endNight
23%11%35%23%6%
631
March1st to 15thNight
22%10%35%28%4
720
16th to endNight
20%7%36%26%7%1
768
April1st to 15thNight
27%10%30%25%6%
637
16th to endNight
30%8%27%24%8%
540
May1st to 15thNight
25%5%31%30%5%
540
16th to endNight
28%5%33%27%6%
418
June1st to 15thNight
23%426%35%10%
360
16th to endNight
21%6%28%32%10%
360
July1st to 15thNight
20%224%35%16%
340
16th to endNight
16%322%39%16%
376
August1st to 15thNight
17%218%42%19%
524
16th to endNight
14%127%37%16%1
573
September1st to 15thNight
18%5%28%35%11%
669
16th to endNight
16%6%29%34%12%
665
October1st to 15thNight
23%6%31%28%10%
660
16th to endNight
29%10%30%23%6%
704
November1st to 15thNight
25%8%33%23%7%
711
16th to endNight
26%12%28%23%7%
750
December1st to 15thNight
29%8%35%23%3
750
16th to endNight
30%13%29%20%5%
800
Page generated at 2017-09-18 08:38:29. Version ac04

Copyright 2017 A. Danko


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