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Hurricane Ridge Visitor Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hurricane Ridge Visitor Center clear sky chart from 2005-11-05 to 2021-07-27.

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
36%
19430
11%
62065
9%
19401
40%
19401
16%
45319

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%
1050
8%
3586
6%
1046
29%
1046
8%
2930
January16th to endNight
26%
1042
9%
3554
7%
1042
29%
1042
11%
2751
February1st to 15thNight
22%
940
8%
3068
4%
940
28%
940
10%
2469
February16th to endNight
23%
844
11%
2733
8%
844
28%
844
9%
2188
March1st to 15thNight
23%
960
9%
2712
6%
960
26%
960
11%
2187
March16th to endNight
24%
1024
8%
2788
4%
1024
27%
1024
11%
2263
April1st to 15thNight
28%
955
8%
2395
3%
955
30%
955
14%
1921
April16th to endNight
35%
714
12%
2142
7%
714
39%
714
16%
1616
May1st to 15thNight
48%
480
13%
1920
17%
480
53%
480
17%
1257
May16th to endNight
51%
503
8%
2008
10%
502
55%
502
14%
1384
June1st to 15thNight
45%
480
6%
1682
5%
480
47%
480
18%
1142
June16th to endNight
54%
480
8%
1680
7%
480
56%
480
26%
1027
July1st to 15thNight
68%
460
15%
1610
15%
460
72%
460
36%
850
July16th to endNight
76%
496
19%
1810
27%
474
80%
474
46%
793
August1st to 15thNight
79%
590
19%
1916
21%
588
80%
588
42%
985
August16th to endNight
67%
763
25%
2197
19%
763
70%
763
41%
1222
September1st to 15thNight
66%
900
23%
2250
13%
900
68%
900
46%
1321
September16th to endNight
45%
896
17%
2478
12%
896
48%
896
23%
1739
October1st to 15thNight
42%
900
12%
2700
11%
900
45%
900
21%
1879
October16th to endNight
30%
960
13%
2953
8%
960
37%
960
16%
2173
November1st to 15thNight
21%
940
8%
3290
6%
940
26%
940
9%
2650
November16th to endNight
21%
960
7%
3360
3%
960
25%
960
8%
2670
December1st to 15thNight
29%
973
9%
3393
6%
973
33%
973
11%
2654
December16th to endNight
15%
1120
6%
3840
3%
1120
18%
1120
7%
3248

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
11%13%48%7%45%5%46%28%
63594
Night
8%11%48%8%46%5%5%6%29%
62221
Cloud CoverDay
12%12%37%6%35%5%5%6%31%
63594
Night
7%10%37%7%46%6%6%7%33%
62224
TransparencyDay
54%8%12%15%8%1
63253
Night
51%9%12%15%8%2
62066
SeeingDay
19%18%29%20%8%2
11114
Night
12%12%31%24%15%3
19435

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
9%15%6%9%10%5%8%6%4417%
1673
16th to endDay
9%18%5%10%8%47%5%5%6%17%
2076
February1st to 15thDay
11%18%6%12%8%46%5%5%6%14%
2116
16th to endDay
6%20%8%10%9%46%5%45%17%
1906
March1st to 15thDay
6%19%8%10%9%5%7%6%45%16%
2564
16th to endDay
10%26%6%11%8%35%43413%
2844
April1st to 15thDay
11%20%6%10%7%45%6%45%15%
2869
16th to endDay
16%19%5%8%7%45%44418%
3082
May1st to 15thDay
14%13%47%6%45%446%28%
3348
16th to endDay
19%13%5%7%6%35%46%6%21%
3511
June1st to 15thDay
19%12%48%7%45%45%6%21%
3596
16th to endDay
14%9%48%7%35%5%46%30%
3600
July1st to 15thDay
10%5%24434346%48%
3600
16th to endDay
6%313423346%59%
3578
August1st to 15thDay
7%4244245%5%8%50%
2945
16th to endDay
7%5%245%345%6%8%47%
3060
September1st to 15thDay
9%5%25%423346%52%
2700
16th to endDay
12%10%37%6%44446%34%
2468
October1st to 15thDay
13%12%48%7%345%5%6%29%
2250
16th to endDay
14%11%48%7%45%6%6%6%25%
2324
November1st to 15thDay
14%16%6%10%10%47%5%45%14%
1888
16th to endDay
11%17%6%10%7%5%6%5%5%5%18%
1920
December1st to 15thDay
9%12%410%9%5%8%6%45%23%
1884
16th to endDay
8%19%5%11%9%6%8%6%5%414%
1792
January1st to 15thNight
8%14%6%11%9%5%8%6%5%6%16%
3586
16th to endNight
10%11%5%10%9%47%6%6%6%19%
3554
February1st to 15thNight
9%16%6%11%9%45%5%47%18%
3056
16th to endNight
7%17%7%12%8%46%45%5%19%
2733
March1st to 15thNight
414%5%9%10%5%9%8%6%7%16%
2712
16th to endNight
5%15%7%12%9%5%7%7%5%418%
2784
April1st to 15thNight
8%14%5%10%8%5%6%5%5%6%21%
2395
16th to endNight
9%10%5%9%8%47%7%6%7%24%
2142
May1st to 15thNight
6%9%38%8%45%45%7%36%
1920
16th to endNight
9%7%37%7%36%6%6%9%32%
2008
June1st to 15thNight
8%8%37%6%35%5%5%7%37%
1682
16th to endNight
5%426%6%25%6%6%9%42%
1680
July1st to 15thNight
331442335%6%60%
1680
16th to endNight
2213212335%70%
1904
August1st to 15thNight
241331245%8%63%
1924
16th to endNight
431332445%7%58%
2197
September1st to 15thNight
5%31342335%6%59%
2250
16th to endNight
9%7%37%8%35%5%6%6%36%
2478
October1st to 15thNight
10%9%47%7%35%5%6%6%33%
2700
16th to endNight
13%9%39%8%45%5%5%7%26%
2953
November1st to 15thNight
13%14%5%9%10%47%7%5%5%17%
3290
16th to endNight
9%15%5%9%9%5%7%6%6%5%17%
3360
December1st to 15thNight
6%14%5%9%10%5%8%7%5%6%21%
3393
16th to endNight
8%19%6%11%9%5%8%6%5%412%
3840

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
8%13%5%8%8%46%6%6%8%21%
1673
16th to endDay
9%15%48%8%46%6%6%8%21%
2076
February1st to 15thDay
12%17%5%9%8%5%6%5%6%6%17%
2116
16th to endDay
8%18%6%9%8%37%5%5%6%19%
1906
March1st to 15thDay
6%18%6%9%8%46%6%6%6%20%
2564
16th to endDay
11%24%5%8%8%45%45%5%16%
2844
April1st to 15thDay
13%19%47%7%46%5%5%6%18%
2869
16th to endDay
16%17%48%7%35%45%5%22%
3082
May1st to 15thDay
14%12%36%5%35%5%5%7%30%
3348
16th to endDay
21%12%37%5%35%5%5%6%23%
3511
June1st to 15thDay
21%11%37%6%35%45%6%23%
3596
16th to endDay
15%9%36%6%35%6%5%6%30%
3600
July1st to 15thDay
11%7%14424436%49%
3600
16th to endDay
7%5%14322345%59%
3578
August1st to 15thDay
8%5%1442345%8%51%
2945
16th to endDay
7%5%25%5%245%5%8%47%
3060
September1st to 15thDay
10%5%24323335%54%
2700
16th to endDay
13%7%36%5%345%5%7%36%
2468
October1st to 15thDay
12%10%47%6%345%5%7%32%
2250
16th to endDay
11%10%27%7%45%6%6%8%29%
2324
November1st to 15thDay
11%13%6%9%9%5%6%6%6%6%18%
1888
16th to endDay
10%16%48%7%5%6%6%6%6%21%
1920
December1st to 15thDay
7%13%5%6%7%5%6%5%7%7%26%
1884
16th to endDay
7%17%5%9%8%5%6%7%7%6%17%
1792
January1st to 15thNight
7%12%5%8%8%5%7%7%7%8%21%
3585
16th to endNight
8%10%48%8%46%7%7%8%24%
3554
February1st to 15thNight
8%14%5%10%8%46%5%6%7%22%
3056
16th to endNight
7%14%7%9%7%46%5%6%6%23%
2733
March1st to 15thNight
413%48%7%5%7%7%8%9%22%
2712
16th to endNight
6%12%48%8%5%7%7%6%7%23%
2788
April1st to 15thNight
8%14%48%8%47%5%6%6%25%
2395
16th to endNight
9%9%37%7%47%6%6%7%31%
2142
May1st to 15thNight
7%8%26%6%35%45%7%40%
1920
16th to endNight
10%6%26%6%45%6%6%8%34%
2008
June1st to 15thNight
10%8%36%5%35%5%46%40%
1682
16th to endNight
6%315%6%245%6%9%47%
1680
July1st to 15thNight
4415%314335%61%
1680
16th to endNight
3212222226%70%
1904
August1st to 15thNight
3312222347%65%
1924
16th to endNight
4313423447%59%
2197
September1st to 15thNight
6%313324246%61%
2250
16th to endNight
9%6%25%6%35%6%6%6%40%
2478
October1st to 15thNight
9%8%36%7%345%5%6%37%
2700
16th to endNight
10%8%37%7%46%6%6%8%31%
2953
November1st to 15thNight
10%12%48%8%47%6%6%6%23%
3290
16th to endNight
7%11%49%8%5%7%6%7%8%22%
3360
December1st to 15thNight
6%12%47%8%47%7%6%7%26%
3393
16th to endNight
9%15%49%8%47%6%7%7%17%
3840

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
62%11%9%9%6%1
1673
16th to endDay
62%9%11%9%6%2
2076
February1st to 15thDay
66%8%10%7%41
2116
16th to endDay
63%8%10%11%5%
1906
March1st to 15thDay
65%8%11%9%4
2564
16th to endDay
72%5%9%9%2
2844
April1st to 15thDay
68%7%10%9%3
2869
16th to endDay
65%6%8%11%6%
3082
May1st to 15thDay
54%8%14%15%7%
3348
16th to endDay
63%8%14%11%2
3515
June1st to 15thDay
62%8%13%9%4
3596
16th to endDay
54%8%15%13%6%1
3600
July1st to 15thDay
37%7%13%24%14%1
3441
16th to endDay
26%7%15%31%16%2
3409
August1st to 15thDay
31%8%17%26%13%1
2928
16th to endDay
35%8%15%28%11%1
3060
September1st to 15thDay
33%5%13%22%21%3
2700
16th to endDay
48%7%15%15%9%3
2468
October1st to 15thDay
53%7%11%17%8%1
2250
16th to endDay
53%8%13%15%8%1
2324
November1st to 15thDay
67%8%9%8%41
1888
16th to endDay
64%9%5%10%8%1
1920
December1st to 15thDay
59%8%10%12%7%1
1884
16th to endDay
66%11%8%8%4
1792
January1st to 15thNight
61%12%9%9%6%1
3586
16th to endNight
57%10%12%10%6%4
3554
February1st to 15thNight
61%9%10%10%6%1
3068
16th to endNight
62%8%9%12%5%1
2733
March1st to 15thNight
58%11%11%13%4
2712
16th to endNight
62%8%13%11%31
2788
April1st to 15thNight
59%8%14%12%5%
2395
16th to endNight
54%8%10%15%10%
2142
May1st to 15thNight
44%9%15%20%8%1
1921
16th to endNight
47%10%18%18%4
2008
June1st to 15thNight
46%8%19%17%6%
1682
16th to endNight
34%11%22%21%7%2
1680
July1st to 15thNight
25%8%18%28%14%4
1610
16th to endNight
16%6%18%32%21%4
1810
August1st to 15thNight
21%8%17%31%17%3
1916
16th to endNight
25%6%17%29%16%3
2197
September1st to 15thNight
25%6%14%24%22%6%
2250
16th to endNight
44%8%11%17%13%4
2478
October1st to 15thNight
47%6%13%19%12%1
2700
16th to endNight
51%8%12%14%11%1
2953
November1st to 15thNight
62%9%10%11%32
3290
16th to endNight
60%10%10%7%9%2
3360
December1st to 15thNight
56%12%10%11%8%1
3393
16th to endNight
67%10%8%7%41
3840

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
16%24%21%16%16%5%
180
16th to endDay
18%26%29%18%7%1
272
February1st to 15thDay
22%27%33%11%3
416
16th to endDay
20%32%29%13%3
374
March1st to 15thDay
21%30%30%13%3
510
16th to endDay
25%25%31%13%4
544
April1st to 15thDay
24%27%29%13%4
509
16th to endDay
29%22%24%15%6%1
498
May1st to 15thDay
24%16%29%21%7%1
528
16th to endDay
27%15%25%19%8%3
586
June1st to 15thDay
28%18%24%18%7%1
791
16th to endDay
17%15%34%21%9%1
795
July1st to 15thDay
14%10%29%31%11%2
775
16th to endDay
7%10%30%31%13%5%
652
August1st to 15thDay
9%8%26%32%15%7%
479
16th to endDay
8%13%29%29%13%4
524
September1st to 15thDay
14%9%32%30%10%2
495
16th to endDay
19%15%33%20%8%2
495
October1st to 15thDay
21%18%29%18%9%1
495
16th to endDay
18%23%29%15%9%3
464
November1st to 15thDay
19%25%30%15%8%
180
16th to endDay
24%16%29%15%5%8%
180
December1st to 15thDay
17%11%29%19%15%6%
180
16th to endDay
18%17%39%18%5%1
192
January1st to 15thNight
17%22%27%17%12%3
1050
16th to endNight
15%18%33%17%11%3
1042
February1st to 15thNight
15%16%39%21%6%1
944
16th to endNight
15%16%34%24%7%
844
March1st to 15thNight
12%20%37%18%9%1
960
16th to endNight
13%17%37%22%7%1
1024
April1st to 15thNight
13%13%39%24%8%1
955
16th to endNight
11%7%39%25%12%2
714
May1st to 15thNight
9%5%29%33%17%4
481
16th to endNight
12%421%35%23%1
503
June1st to 15thNight
12%6%25%33%20%2
480
16th to endNight
6%427%37%22%2
480
July1st to 15thNight
5%216%36%36%2
460
16th to endNight
3313%36%36%6%
496
August1st to 15thNight
5%19%31%38%13%
590
16th to endNight
6%218%30%34%7%
763
September1st to 15thNight
6%219%31%29%10%
900
16th to endNight
14%428%27%20%4
896
October1st to 15thNight
14%8%28%26%20%3
900
16th to endNight
15%11%38%18%11%5%
960
November1st to 15thNight
18%18%35%20%6%
940
16th to endNight
13%20%38%14%7%5%
960
December1st to 15thNight
13%15%34%23%10%2
973
16th to endNight
17%22%37%15%5%
1120
Page generated at 2021-07-28 15:31:13. Version ac04

Copyright 2021 A. Danko


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