Milo McIver State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Milo McIver State Park clear sky chart from 2005-11-05 to 2017-09-22.

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%
14682
12%
46925
11%
14654
43%
14654
16%
34372

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
26%
718
9%
2506
5%
716
31%
716
10%
1992
January16th to endNight
29%
768
12%
2598
9%
768
34%
768
12%
1977
February1st to 15thNight
28%
700
6%
2288
5%
699
30%
699
9%
1868
February16th to endNight
25%
632
10%
1993
5%
632
32%
632
9%
1590
March1st to 15thNight
30%
720
6%
2055
5%
720
31%
720
10%
1714
March16th to endNight
26%
768
6%
2072
4%
768
28%
768
10%
1780
April1st to 15thNight
30%
719
6%
1799
3%
719
30%
719
11%
1539
April16th to endNight
39%
618
8%
1698
5%
618
40%
618
14%
1342
May1st to 15thNight
46%
376
13%
1456
16%
376
49%
376
16%
997
May16th to endNight
45%
375
7%
1496
11%
374
45%
374
10%
1152
June1st to 15thNight
46%
360
6%
1440
9%
360
47%
360
12%
1047
June16th to endNight
53%
360
10%
1440
16%
360
55%
360
18%
937
July1st to 15thNight
79%
340
16%
1360
27%
340
80%
340
37%
645
July16th to endNight
81%
376
27%
1416
40%
354
84%
354
45%
593
August1st to 15thNight
82%
508
24%
1582
25%
506
83%
506
46%
781
August16th to endNight
75%
669
29%
1815
23%
669
75%
669
48%
973
September1st to 15thNight
71%
720
26%
1800
15%
720
73%
720
51%
1011
September16th to endNight
60%
683
22%
1873
19%
683
61%
683
29%
1246
October1st to 15thNight
47%
660
16%
1980
16%
660
49%
660
22%
1376
October16th to endNight
39%
704
11%
2147
11%
704
40%
704
14%
1643
November1st to 15thNight
26%
700
8%
2383
7%
700
29%
700
8%
1962
November16th to endNight
27%
720
6%
2520
4%
720
30%
720
10%
1977
December1st to 15thNight
27%
720
8%
2520
6%
720
30%
720
11%
1968
December16th to endNight
22%
768
6%
2688
5%
768
23%
768
7%
2262

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
23%8%35%5%24345%33%
47981
Night
25%8%35%423345%33%
47093
Cloud CoverDay
24%8%35%423345%33%
47981
Night
25%9%35%423345%32%
47097
TransparencyDay
55%410%16%10%3
47652
Night
55%5%9%15%10%3
46926
SeeingDay
29%10%23%25%8%2
5637
Night
31%6%14%26%17%2
14689

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
36%9%37%6%2333320%
1432
16th to endDay
31%10%25%423335%26%
1626
February1st to 15thDay
31%10%46%6%15%446%17%
1576
16th to endDay
31%12%48%43433319%
1481
March1st to 15thDay
33%10%47%6%25%446%13%
1904
16th to endDay
33%12%5%8%6%245%35%13%
2151
April1st to 15thDay
30%12%48%6%3444416%
2149
16th to endDay
27%10%47%5%23445%22%
2259
May1st to 15thDay
24%8%35%5%23336%33%
2493
16th to endDay
29%7%36%5%24446%25%
2615
June1st to 15thDay
26%10%46%5%34345%25%
2520
16th to endDay
16%7%35%5%34446%38%
2520
July1st to 15thDay
7%313323346%60%
2520
16th to endDay
8%41232223463%
2657
August1st to 15thDay
5%31342435%6%59%
2368
16th to endDay
7%413323346%58%
2387
September1st to 15thDay
8%413323346%59%
2160
16th to endDay
18%6%35%5%33346%39%
1897
October1st to 15thDay
22%7%36%5%2345%6%32%
1650
16th to endDay
29%7%36%5%33345%27%
1724
November1st to 15thDay
37%6%38%5%23446%15%
1476
16th to endDay
30%10%46%6%25%44420%
1440
December1st to 15thDay
30%11%46%6%2434420%
1440
16th to endDay
36%13%35%42333318%
1536
January1st to 15thNight
34%9%45%5%2334322%
2506
16th to endNight
30%9%35%5%3324426%
2598
February1st to 15thNight
32%10%35%5%24335%21%
2276
16th to endNight
29%12%36%423345%23%
1993
March1st to 15thNight
32%10%36%5%25%44420%
2055
16th to endNight
31%11%47%5%34446%16%
2068
April1st to 15thNight
29%13%46%5%25%336%19%
1799
16th to endNight
26%10%25%424446%28%
1698
May1st to 15thNight
20%8%345%24346%36%
1456
16th to endNight
26%6%25%5%345%48%25%
1496
June1st to 15thNight
21%8%46%42444433%
1440
16th to endNight
15%7%25%5%24335%42%
1440
July1st to 15thNight
5%213312246%66%
1440
16th to endNight
3213212246%70%
1512
August1st to 15thNight
2212322348%64%
1590
16th to endNight
5%313223225%67%
1815
September1st to 15thNight
7%31221123469%
1800
16th to endNight
17%413424246%46%
1873
October1st to 15thNight
22%6%35%422335%40%
1980
16th to endNight
26%6%26%5%3345%5%29%
2147
November1st to 15thNight
37%7%36%5%2434419%
2383
16th to endNight
33%8%35%5%2433325%
2520
December1st to 15thNight
33%9%36%423325%24%
2520
16th to endNight
35%13%46%43333317%
2688

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
36%9%37%5%3333320%
1432
16th to endDay
31%11%2441334426%
1626
February1st to 15thDay
30%12%46%5%24445%18%
1576
16th to endDay
30%14%46%5%25%23419%
1481
March1st to 15thDay
34%12%5%6%6%3434414%
1904
16th to endDay
34%13%5%7%5%34435%12%
2151
April1st to 15thDay
30%14%48%6%2433416%
2149
16th to endDay
29%12%46%5%23345%22%
2259
May1st to 15thDay
25%9%35%422335%33%
2493
16th to endDay
32%8%36%424445%24%
2615
June1st to 15thDay
29%9%46%5%33245%25%
2520
16th to endDay
19%7%25%5%24446%37%
2520
July1st to 15thDay
7%313323336%60%
2520
16th to endDay
9%312223225%63%
2657
August1st to 15thDay
5%413424346%58%
2368
16th to endDay
7%413223346%58%
2387
September1st to 15thDay
8%423313346%58%
2160
16th to endDay
20%7%34423435%39%
1897
October1st to 15thDay
23%7%25%5%24346%33%
1650
16th to endDay
30%8%35%433435%27%
1724
November1st to 15thDay
38%7%47%5%23346%16%
1476
16th to endDay
32%8%46%5%335%3420%
1440
December1st to 15thDay
30%12%5%5%425%34421%
1440
16th to endDay
37%13%3442333318%
1536
January1st to 15thNight
33%11%35%42423422%
2506
16th to endNight
30%10%44433245%26%
2598
February1st to 15thNight
31%12%36%434345%20%
2276
16th to endNight
30%13%35%423335%23%
1993
March1st to 15thNight
31%11%36%5%35%34420%
2055
16th to endNight
31%14%47%424445%16%
2072
April1st to 15thNight
30%14%45%5%25%325%19%
1799
16th to endNight
28%10%25%324345%27%
1698
May1st to 15thNight
23%8%24413446%35%
1456
16th to endNight
28%6%35%43445%7%24%
1496
June1st to 15thNight
23%9%46%325%336%31%
1440
16th to endNight
17%7%26%5%24445%40%
1440
July1st to 15thNight
5%31221334465%
1440
16th to endNight
3213212346%68%
1512
August1st to 15thNight
3212224349%63%
1590
16th to endNight
5%313313225%66%
1815
September1st to 15thNight
7%31231223468%
1800
16th to endNight
18%5%13334246%45%
1873
October1st to 15thNight
23%8%25%322235%40%
1980
16th to endNight
27%6%26%5%24445%28%
2147
November1st to 15thNight
38%8%26%5%24335%18%
2383
16th to endNight
33%9%35%5%2333425%
2520
December1st to 15thNight
32%10%45%423235%24%
2520
16th to endNight
35%14%36%5%2333416%
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
70%36%9%7%2
1432
16th to endDay
62%47%11%9%5%
1626
February1st to 15thDay
69%6%9%9%5%
1576
16th to endDay
71%38%9%6%1
1481
March1st to 15thDay
73%5%7%9%3
1904
16th to endDay
77%47%7%2
2151
April1st to 15thDay
73%6%8%8%2
2149
16th to endDay
67%5%9%10%5%1
2259
May1st to 15thDay
56%311%19%8%
2493
16th to endDay
63%7%11%14%2
2619
June1st to 15thDay
63%414%12%4
2520
16th to endDay
49%5%15%20%7%2
2520
July1st to 15thDay
26%5%13%26%22%6%
2371
16th to endDay
23%37%25%32%6%
2490
August1st to 15thDay
25%5%14%30%18%6%
2351
16th to endDay
28%411%29%20%5%
2387
September1st to 15thDay
27%310%24%21%12%
2160
16th to endDay
47%411%17%12%5%
1897
October1st to 15thDay
52%411%18%9%4
1650
16th to endDay
58%6%9%12%11%1
1724
November1st to 15thDay
70%49%11%3
1476
16th to endDay
68%5%6%6%11%
1440
December1st to 15thDay
67%5%7%9%8%1
1440
16th to endDay
71%47%10%4
1536
January1st to 15thNight
66%38%9%8%2
2506
16th to endNight
61%47%10%9%7%
2598
February1st to 15thNight
67%5%8%9%6%2
2288
16th to endNight
65%5%8%11%7%1
1993
March1st to 15thNight
68%5%8%12%3
2055
16th to endNight
71%5%9%10%3
2072
April1st to 15thNight
70%5%11%8%4
1799
16th to endNight
61%5%13%13%41
1698
May1st to 15thNight
52%411%20%8%2
1457
16th to endNight
61%7%12%13%31
1496
June1st to 15thNight
57%6%15%14%5%
1440
16th to endNight
48%415%21%6%3
1440
July1st to 15thNight
23%6%12%28%22%7%
1360
16th to endNight
18%47%27%30%10%
1416
August1st to 15thNight
21%415%32%17%8%
1582
16th to endNight
22%412%33%19%7%
1815
September1st to 15thNight
23%312%24%19%16%
1800
16th to endNight
41%5%10%19%14%7%
1873
October1st to 15thNight
49%48%17%16%4
1980
16th to endNight
58%6%7%11%12%3
2147
November1st to 15thNight
69%5%7%10%6%
2383
16th to endNight
65%46%8%10%4
2520
December1st to 15thNight
64%48%12%9%
2520
16th to endNight
73%47%8%5%
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
35%11%26%15%10%1
60
16th to endDay
46%5%19%16%11%1
154
February1st to 15thDay
42%12%20%19%4
236
16th to endDay
38%19%26%14%1
221
March1st to 15thDay
49%17%20%11%2
270
16th to endDay
47%15%21%11%2
288
April1st to 15thDay
38%18%18%17%6%1
269
16th to endDay
42%14%22%15%31
270
May1st to 15thDay
35%14%22%21%41
288
16th to endDay
38%7%17%24%8%2
330
June1st to 15thDay
32%11%23%20%10%1
315
16th to endDay
18%9%30%30%8%2
315
July1st to 15thDay
6%6%28%40%14%3
305
16th to endDay
7%5%29%41%12%3
327
August1st to 15thDay
8%5%21%42%16%5%
315
16th to endDay
6%6%25%38%16%6%
332
September1st to 15thDay
12%7%27%34%14%3
315
16th to endDay
26%8%22%31%10%
280
October1st to 15thDay
31%11%21%27%7%
255
16th to endDay
39%8%23%20%6%2
236
November1st to 15thDay
29%11%27%26%22
72
16th to endDay
40%13%26%13%6%
60
December1st to 15thDay
48%28%18%5%
60
16th to endDay
42%12%15%21%7%
64
January1st to 15thNight
40%10%18%22%7%
720
16th to endNight
36%7%19%23%11%1
768
February1st to 15thNight
37%7%19%26%7%1
704
16th to endNight
39%12%17%21%8%
632
March1st to 15thNight
40%10%15%23%9%
720
16th to endNight
41%8%16%21%10%
768
April1st to 15thNight
41%8%15%21%13%1
719
16th to endNight
37%5%12%23%16%3
618
May1st to 15thNight
31%5%11%28%20%2
377
16th to endNight
34%311%24%24%1
375
June1st to 15thNight
31%5%12%28%20%2
360
16th to endNight
21%5%11%35%24%1
360
July1st to 15thNight
7%17%35%45%2
340
16th to endNight
427%40%42%2
376
August1st to 15thNight
6%6%26%50%10%
508
16th to endNight
8%28%37%34%8%
669
September1st to 15thNight
10%212%30%36%6%
720
16th to endNight
23%38%32%28%3
683
October1st to 15thNight
28%415%28%19%3
660
16th to endNight
30%6%16%27%15%2
704
November1st to 15thNight
42%10%15%24%7%
700
16th to endNight
41%9%16%23%7%
720
December1st to 15thNight
40%6%20%25%5%
720
16th to endNight
44%10%18%19%7%
768
Page generated at 2017-09-23 03:43:39. Version ac04

Copyright 2017 A. Danko


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