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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 2019-07-11.

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
37%
16866
10%
54005
9%
16837
40%
16837
15%
39819

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
30%
900
8%
3136
7%
896
32%
896
9%
2539
January16th to endNight
28%
908
9%
3110
8%
908
31%
908
11%
2408
February1st to 15thNight
23%
820
8%
2678
5%
820
28%
820
10%
2168
February16th to endNight
24%
736
9%
2384
7%
736
27%
736
9%
1930
March1st to 15thNight
23%
840
8%
2374
6%
840
25%
840
11%
1947
March16th to endNight
22%
896
6%
2440
3%
896
24%
896
10%
2035
April1st to 15thNight
24%
836
5%
2096
2%
836
26%
836
12%
1750
April16th to endNight
32%
624
10%
1872
6%
624
36%
624
16%
1416
May1st to 15thNight
50%
419
13%
1679
18%
419
53%
419
17%
1107
May16th to endNight
55%
439
8%
1752
11%
438
58%
438
15%
1202
June1st to 15thNight
49%
420
6%
1471
5%
420
50%
420
19%
984
June16th to endNight
53%
420
7%
1470
7%
420
55%
420
24%
924
July1st to 15thNight
70%
392
15%
1372
15%
392
74%
392
37%
712
July16th to endNight
80%
408
18%
1474
28%
386
84%
386
46%
645
August1st to 15thNight
80%
510
19%
1656
22%
508
81%
508
43%
834
August16th to endNight
68%
662
24%
1904
19%
662
71%
662
42%
1051
September1st to 15thNight
68%
780
23%
1950
14%
780
70%
780
46%
1138
September16th to endNight
48%
776
17%
2149
13%
776
50%
776
24%
1506
October1st to 15thNight
42%
780
13%
2340
12%
780
45%
780
21%
1642
October16th to endNight
31%
832
11%
2560
8%
832
35%
832
15%
1922
November1st to 15thNight
17%
820
7%
2870
5%
820
22%
820
8%
2364
November16th to endNight
21%
840
5%
2940
3%
840
23%
840
8%
2381
December1st to 15thNight
29%
848
8%
2968
7%
848
32%
848
10%
2354
December16th to endNight
14%
960
6%
3360
3%
960
17%
960
6%
2860

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%13%48%7%45%5%46%27%
55221
Night
8%11%49%8%46%5%5%6%28%
54161
Cloud CoverDay
12%12%47%6%35%5%5%6%29%
55221
Night
8%10%37%7%46%6%6%7%32%
54164
TransparencyDay
56%8%12%14%7%1
54880
Night
52%9%12%15%8%2
54006
SeeingDay
20%17%29%21%9%2
8437
Night
12%11%30%23%16%3
16871

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
10%14%5%10%10%5%8%6%4417%
1463
16th to endDay
10%18%5%10%7%47%5%5%6%18%
1817
February1st to 15thDay
10%17%6%13%9%5%6%5%5%6%13%
1846
16th to endDay
7%19%8%11%9%46%5%4416%
1661
March1st to 15thDay
6%20%8%10%9%5%8%6%4414%
2243
16th to endDay
11%27%6%12%8%35%43411%
2488
April1st to 15thDay
13%22%6%10%8%46%6%45%10%
2509
16th to endDay
16%20%6%8%7%45%5%4416%
2692
May1st to 15thDay
15%13%47%6%44446%28%
2930
16th to endDay
20%12%5%7%7%35%46%6%21%
3063
June1st to 15thDay
18%10%48%7%45%5%5%6%22%
3146
16th to endDay
15%9%49%7%35%5%45%26%
3150
July1st to 15thDay
10%5%34434347%47%
3080
16th to endDay
7%314423347%57%
2953
August1st to 15thDay
7%4244245%5%9%50%
2546
16th to endDay
7%5%25%5%345%6%7%46%
2649
September1st to 15thDay
8%5%24423346%52%
2340
16th to endDay
12%9%37%6%445%45%34%
2138
October1st to 15thDay
14%12%49%7%3445%6%29%
1950
16th to endDay
14%10%48%8%46%6%5%5%24%
2012
November1st to 15thDay
16%15%5%11%10%47%5%4412%
1648
16th to endDay
11%18%5%10%8%5%6%5%5%5%16%
1680
December1st to 15thDay
9%12%410%9%6%8%6%4423%
1649
16th to endDay
8%19%6%10%9%6%8%6%5%414%
1568
January1st to 15thNight
8%12%5%10%10%5%8%6%5%6%18%
3136
16th to endNight
10%11%5%10%9%5%7%6%7%6%19%
3110
February1st to 15thNight
9%14%6%12%10%5%5%5%46%18%
2666
16th to endNight
7%16%7%12%9%5%6%5%5%5%18%
2384
March1st to 15thNight
5%15%5%9%10%5%9%9%6%7%15%
2374
16th to endNight
5%15%7%12%10%6%8%7%5%415%
2436
April1st to 15thNight
9%16%5%12%8%5%7%6%5%6%15%
2096
16th to endNight
9%11%5%9%7%47%7%6%8%22%
1872
May1st to 15thNight
6%9%38%8%45%5%5%6%36%
1679
16th to endNight
9%7%36%7%36%6%6%9%32%
1752
June1st to 15thNight
9%7%37%6%35%46%7%38%
1471
16th to endNight
6%426%7%25%6%6%10%40%
1470
July1st to 15thNight
322442335%7%59%
1442
16th to endNight
3213113235%70%
1568
August1st to 15thNight
231331235%7%65%
1664
16th to endNight
431432435%7%59%
1904
September1st to 15thNight
421342435%5%60%
1950
16th to endNight
10%6%37%8%45%5%6%6%36%
2149
October1st to 15thNight
10%8%5%7%7%35%5%5%6%33%
2340
16th to endNight
13%10%310%8%5%6%5%5%7%24%
2560
November1st to 15thNight
14%14%5%10%10%47%7%5%5%14%
2870
16th to endNight
10%16%5%9%10%5%8%6%6%5%16%
2940
December1st to 15thNight
6%14%5%9%10%5%8%6%5%5%21%
2968
16th to endNight
9%19%5%12%9%5%8%6%5%412%
3360

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
9%13%6%8%8%5%6%6%7%7%20%
1463
16th to endDay
10%16%49%8%46%6%5%8%21%
1817
February1st to 15thDay
10%16%5%10%9%5%6%5%6%6%16%
1846
16th to endDay
9%19%6%9%8%37%5%5%6%18%
1661
March1st to 15thDay
6%19%6%10%8%46%6%6%6%18%
2243
16th to endDay
12%25%5%8%7%45%45%414%
2488
April1st to 15thDay
14%20%47%8%46%6%6%6%13%
2509
16th to endDay
16%17%48%7%35%45%5%20%
2692
May1st to 15thDay
15%11%36%5%35%5%5%7%30%
2930
16th to endDay
22%12%36%5%35%45%6%22%
3063
June1st to 15thDay
21%10%37%6%45%45%6%23%
3146
16th to endDay
17%9%36%6%45%5%5%6%26%
3150
July1st to 15thDay
11%6%145%24436%48%
3080
16th to endDay
8%5%15%322345%57%
2953
August1st to 15thDay
8%5%25%42345%9%50%
2546
16th to endDay
7%5%25%5%245%5%8%47%
2649
September1st to 15thDay
10%425%323335%54%
2340
16th to endDay
14%7%37%5%35%5%47%36%
2138
October1st to 15thDay
13%10%48%6%345%46%31%
1950
16th to endDay
12%10%37%7%45%6%7%8%27%
2012
November1st to 15thDay
12%13%6%9%9%5%7%6%6%7%15%
1648
16th to endDay
10%17%49%8%5%7%6%6%6%18%
1680
December1st to 15thDay
7%13%46%7%5%7%6%7%7%25%
1649
16th to endDay
7%17%5%9%8%5%6%7%7%6%17%
1568
January1st to 15thNight
7%11%5%8%8%5%7%7%7%8%22%
3135
16th to endNight
9%11%47%8%46%7%7%8%24%
3110
February1st to 15thNight
8%13%5%10%8%46%5%6%7%21%
2666
16th to endNight
7%14%8%9%7%46%5%6%6%21%
2384
March1st to 15thNight
414%49%7%47%7%8%9%21%
2374
16th to endNight
6%13%49%9%5%8%7%7%7%19%
2440
April1st to 15thNight
9%15%48%8%5%7%5%6%6%21%
2096
16th to endNight
8%10%38%7%47%6%6%7%29%
1872
May1st to 15thNight
7%7%36%6%35%5%5%7%40%
1679
16th to endNight
10%6%26%6%45%6%6%9%35%
1752
June1st to 15thNight
9%8%36%5%245%46%41%
1471
16th to endNight
6%315%7%35%5%6%9%44%
1470
July1st to 15thNight
4316%314336%61%
1442
16th to endNight
3212222326%69%
1568
August1st to 15thNight
3212212337%66%
1664
16th to endNight
3313423447%59%
1904
September1st to 15thNight
5%214324336%62%
1950
16th to endNight
10%6%26%6%35%6%6%7%39%
2149
October1st to 15thNight
10%8%36%8%345%5%6%36%
2340
16th to endNight
10%8%38%7%46%6%6%8%29%
2560
November1st to 15thNight
11%13%49%8%48%6%6%6%20%
2870
16th to endNight
8%12%410%8%5%7%6%7%8%20%
2940
December1st to 15thNight
6%12%47%8%48%7%6%7%24%
2968
16th to endNight
9%15%49%8%48%7%7%6%17%
3360

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
63%11%8%8%6%2
1463
16th to endDay
62%9%10%9%6%2
1817
February1st to 15thDay
68%9%10%6%41
1846
16th to endDay
65%8%9%11%4
1661
March1st to 15thDay
68%9%10%9%3
2243
16th to endDay
75%5%8%9%1
2488
April1st to 15thDay
73%7%9%7%2
2509
16th to endDay
68%6%8%11%4
2692
May1st to 15thDay
55%8%14%14%7%
2930
16th to endDay
65%7%13%11%1
3067
June1st to 15thDay
61%9%14%10%4
3146
16th to endDay
59%7%14%12%4
3150
July1st to 15thDay
39%7%13%24%13%1
2921
16th to endDay
28%7%15%27%17%2
2784
August1st to 15thDay
33%8%16%26%13%2
2529
16th to endDay
36%7%15%27%11%1
2649
September1st to 15thDay
33%5%14%23%20%2
2340
16th to endDay
48%7%14%15%10%2
2138
October1st to 15thDay
54%7%11%17%8%
1950
16th to endDay
55%8%12%14%8%1
2012
November1st to 15thDay
69%8%9%8%31
1648
16th to endDay
67%9%410%6%1
1680
December1st to 15thDay
59%8%10%12%7%1
1649
16th to endDay
66%11%7%8%4
1568
January1st to 15thNight
59%12%9%9%7%1
3136
16th to endNight
57%10%11%10%6%4
3110
February1st to 15thNight
62%9%9%10%6%1
2678
16th to endNight
63%8%8%13%4
2384
March1st to 15thNight
60%11%11%12%3
2374
16th to endNight
65%9%11%10%3
2440
April1st to 15thNight
64%8%12%10%3
2096
16th to endNight
54%8%11%15%9%
1872
May1st to 15thNight
44%9%16%20%8%1
1680
16th to endNight
47%10%18%19%3
1752
June1st to 15thNight
44%9%20%18%6%
1471
16th to endNight
35%11%23%21%5%2
1470
July1st to 15thNight
24%7%17%30%15%4
1372
16th to endNight
17%5%17%32%21%5%
1474
August1st to 15thNight
20%8%16%32%17%4
1656
16th to endNight
24%6%18%30%15%3
1904
September1st to 15thNight
24%6%15%25%22%6%
1950
16th to endNight
44%8%11%17%14%3
2149
October1st to 15thNight
48%6%12%20%12%
2340
16th to endNight
54%8%12%12%11%1
2560
November1st to 15thNight
65%9%10%10%22
2870
16th to endNight
62%10%9%7%7%1
2940
December1st to 15thNight
58%12%9%10%7%1
2968
16th to endNight
67%11%7%7%41
3360

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
10%12%23%21%24%7%
120
16th to endDay
20%22%27%19%9%1
198
February1st to 15thDay
20%25%35%13%3
326
16th to endDay
17%33%29%15%3
291
March1st to 15thDay
22%30%28%14%4
390
16th to endDay
27%26%30%10%4
416
April1st to 15thDay
28%25%29%11%3
389
16th to endDay
33%21%25%14%41
378
May1st to 15thDay
25%15%27%22%7%1
408
16th to endDay
27%12%25%21%9%4
458
June1st to 15thDay
26%16%26%20%8%1
641
16th to endDay
20%16%32%19%9%1
645
July1st to 15thDay
15%9%30%30%12%2
602
16th to endDay
9%6%30%32%14%6%
462
August1st to 15thDay
10%6%25%33%15%8%
359
16th to endDay
9%11%28%30%13%6%
396
September1st to 15thDay
14%9%29%32%11%2
375
16th to endDay
18%14%33%22%8%2
375
October1st to 15thDay
23%18%30%18%8%1
375
16th to endDay
18%18%28%18%11%4
345
November1st to 15thDay
19%25%36%13%4
120
16th to endDay
27%13%28%13%5%12%
120
December1st to 15thDay
15%15%26%15%18%8%
120
16th to endDay
15%12%47%17%5%
128
January1st to 15thNight
16%18%27%19%14%3
900
16th to endNight
15%16%32%18%12%3
908
February1st to 15thNight
13%14%39%23%7%1
824
16th to endNight
13%15%36%25%8%
736
March1st to 15thNight
13%19%36%18%10%1
840
16th to endNight
13%17%38%21%7%1
896
April1st to 15thNight
14%13%38%23%8%1
836
16th to endNight
12%7%40%25%11%2
624
May1st to 15thNight
10%427%33%19%4
420
16th to endNight
11%320%35%26%1
439
June1st to 15thNight
11%5%23%34%22%3
420
16th to endNight
6%426%36%23%2
420
July1st to 15thNight
4215%35%38%3
392
16th to endNight
3211%32%41%7%
408
August1st to 15thNight
5%8%29%40%15%
510
16th to endNight
5%217%28%37%8%
662
September1st to 15thNight
6%217%31%30%11%
780
16th to endNight
14%326%28%21%5%
776
October1st to 15thNight
14%6%28%26%19%3
780
16th to endNight
15%9%37%18%12%6%
832
November1st to 15thNight
19%18%38%17%6%
820
16th to endNight
15%19%36%14%8%5%
840
December1st to 15thNight
13%15%33%22%11%2
848
16th to endNight
17%21%39%14%6%
960
Page generated at 2019-07-12 04:32:34. Version ac04

Copyright 2019 A. Danko


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