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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 2017-09-10.

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%
14524
10%
46643
8%
14495
39%
14495
15%
34777

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
29%
750
9%
2686
8%
746
31%
746
9%
2172
January16th to endNight
29%
774
9%
2666
8%
774
32%
774
11%
2068
February1st to 15thNight
24%
700
6%
2288
4%
700
28%
700
9%
1876
February16th to endNight
25%
632
9%
2047
7%
632
28%
632
9%
1667
March1st to 15thNight
18%
720
5%
2034
3%
720
20%
720
8%
1724
March16th to endNight
19%
768
5%
2091
2%
768
21%
768
8%
1788
April1st to 15thNight
28%
716
6%
1796
3%
716
30%
716
12%
1485
April16th to endNight
33%
540
10%
1620
6%
540
37%
540
15%
1244
May1st to 15thNight
47%
359
11%
1439
16%
359
51%
359
15%
980
May16th to endNight
50%
375
7%
1496
9%
374
54%
374
14%
1050
June1st to 15thNight
46%
360
5%
1261
4%
360
47%
360
18%
862
June16th to endNight
51%
360
8%
1260
7%
360
52%
360
22%
817
July1st to 15thNight
72%
340
14%
1190
14%
340
76%
340
40%
595
July16th to endNight
77%
376
18%
1352
27%
354
81%
354
44%
613
August1st to 15thNight
80%
479
18%
1553
20%
477
81%
477
42%
794
August16th to endNight
68%
611
24%
1757
19%
611
70%
611
41%
978
September1st to 15thNight
68%
700
23%
1750
14%
700
70%
700
47%
1016
September16th to endNight
46%
656
18%
1817
13%
656
49%
656
23%
1288
October1st to 15thNight
40%
660
11%
1980
10%
660
42%
660
19%
1423
October16th to endNight
28%
704
8%
2166
5%
704
33%
704
13%
1686
November1st to 15thNight
16%
700
6%
2450
4%
700
20%
700
6%
2071
November16th to endNight
23%
720
5%
2520
3%
720
26%
720
8%
2045
December1st to 15thNight
25%
724
6%
2544
4%
724
28%
724
9%
2067
December16th to endNight
15%
800
5%
2880
3%
800
18%
800
6%
2468

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%5%8%7%45%5%45%26%
48009
Night
8%11%49%8%46%5%5%6%27%
46799
Cloud CoverDay
12%12%47%6%35%5%5%6%28%
48009
Night
8%10%47%7%46%6%6%7%31%
46802
TransparencyDay
57%8%11%14%7%1
47668
Night
53%9%12%14%8%1
46644
SeeingDay
21%18%30%20%7%2
6125
Night
12%12%31%23%15%3
14529

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%16%6%9%9%5%8%6%4417%
1253
16th to endDay
11%18%5%10%7%47%446%19%
1557
February1st to 15thDay
10%18%6%12%9%5%7%5%5%6%13%
1576
16th to endDay
8%21%8%10%8%46%5%4416%
1427
March1st to 15thDay
7%21%9%10%9%5%8%6%4412%
1923
16th to endDay
12%28%6%12%8%45%4339%
2133
April1st to 15thDay
13%22%6%11%8%45%6%5%5%10%
2149
16th to endDay
16%21%6%9%7%46%5%4414%
2340
May1st to 15thDay
16%14%47%6%44445%25%
2510
16th to endDay
21%12%5%7%7%45%5%6%5%17%
2615
June1st to 15thDay
19%11%48%7%45%5%5%6%22%
2697
16th to endDay
16%10%49%8%35%5%45%25%
2700
July1st to 15thDay
9%5%24434347%50%
2700
16th to endDay
7%414423447%54%
2723
August1st to 15thDay
7%425%4245%6%8%48%
2397
16th to endDay
7%5%25%5%345%6%7%45%
2444
September1st to 15thDay
8%5%24423346%53%
2097
16th to endDay
13%9%38%6%445%45%34%
1810
October1st to 15thDay
13%12%410%7%345%5%6%26%
1650
16th to endDay
15%10%49%8%46%6%5%5%21%
1703
November1st to 15thDay
16%16%5%11%10%5%7%5%4411%
1408
16th to endDay
12%19%6%10%7%5%6%44417%
1440
December1st to 15thDay
10%13%5%10%9%6%8%6%3420%
1413
16th to endDay
8%20%5%10%8%6%8%6%5%414%
1344
January1st to 15thNight
9%13%6%10%10%5%9%6%5%5%18%
2686
16th to endNight
11%11%5%11%8%47%5%6%6%20%
2666
February1st to 15thNight
8%15%7%12%10%5%6%5%46%17%
2276
16th to endNight
9%16%6%12%9%5%7%5%45%18%
2047
March1st to 15thNight
5%15%6%10%10%5%10%9%6%6%12%
2034
16th to endNight
6%16%8%13%10%6%8%7%5%412%
2087
April1st to 15thNight
9%15%5%12%8%5%7%6%5%6%17%
1796
16th to endNight
8%11%5%8%7%48%7%6%8%21%
1620
May1st to 15thNight
7%10%39%8%5%5%5%45%34%
1439
16th to endNight
9%7%46%7%46%6%6%9%29%
1496
June1st to 15thNight
9%8%37%6%35%45%6%38%
1261
16th to endNight
6%5%36%7%35%6%6%9%39%
1260
July1st to 15thNight
321342335%6%61%
1260
16th to endNight
3223223345%67%
1446
August1st to 15thNight
241331345%7%63%
1561
16th to endNight
441432445%7%58%
1757
September1st to 15thNight
5%21342435%5%61%
1750
16th to endNight
11%6%36%8%46%5%6%6%35%
1817
October1st to 15thNight
11%8%5%8%7%36%5%5%6%31%
1980
16th to endNight
14%11%311%8%5%6%5%5%6%21%
2166
November1st to 15thNight
15%15%5%10%10%5%8%6%4413%
2450
16th to endNight
9%16%6%9%10%5%8%5%5%5%16%
2520
December1st to 15thNight
7%15%6%9%10%6%8%6%45%18%
2544
16th to endNight
9%19%5%11%9%5%9%6%5%412%
2880

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%6%9%7%47%6%7%7%20%
1253
16th to endDay
11%15%49%7%36%5%5%8%21%
1557
February1st to 15thDay
10%16%5%9%9%6%7%5%6%6%16%
1576
16th to endDay
10%19%5%9%8%36%5%5%7%17%
1427
March1st to 15thDay
7%19%6%10%8%46%6%6%6%16%
1923
16th to endDay
13%26%5%9%8%5%5%45%412%
2133
April1st to 15thDay
13%21%47%8%46%5%6%6%13%
2149
16th to endDay
16%19%5%9%7%36%45%5%18%
2340
May1st to 15thDay
17%12%36%5%35%5%5%6%27%
2510
16th to endDay
23%12%46%5%36%5%5%6%19%
2615
June1st to 15thDay
21%10%37%6%45%446%24%
2697
16th to endDay
18%10%47%7%45%6%5%6%25%
2700
July1st to 15thDay
10%6%145%24436%50%
2700
16th to endDay
8%5%25%323346%54%
2723
August1st to 15thDay
8%5%25%42445%9%48%
2397
16th to endDay
7%5%25%6%245%5%8%46%
2444
September1st to 15thDay
9%425%323335%55%
2097
16th to endDay
13%6%37%5%345%5%7%36%
1810
October1st to 15thDay
13%10%49%6%345%5%7%29%
1650
16th to endDay
12%10%37%7%45%7%7%8%24%
1703
November1st to 15thDay
13%13%5%10%10%5%7%5%6%7%14%
1408
16th to endDay
10%16%49%8%5%7%5%5%6%18%
1440
December1st to 15thDay
8%14%5%7%7%5%7%5%7%7%23%
1413
16th to endDay
7%17%5%9%8%6%6%7%8%6%16%
1344
January1st to 15thNight
7%10%5%8%8%5%7%7%7%8%22%
2685
16th to endNight
9%11%47%8%46%7%7%7%24%
2666
February1st to 15thNight
7%14%5%11%9%5%7%6%6%8%19%
2276
16th to endNight
8%14%7%8%7%5%6%6%6%7%21%
2047
March1st to 15thNight
5%14%49%8%48%8%9%9%17%
2034
16th to endNight
6%13%5%9%9%5%8%8%7%7%16%
2091
April1st to 15thNight
8%14%47%8%5%7%6%6%7%22%
1796
16th to endNight
8%10%38%7%37%6%7%7%28%
1620
May1st to 15thNight
8%8%36%7%46%5%5%6%37%
1439
16th to endNight
11%5%37%7%46%6%6%9%32%
1496
June1st to 15thNight
10%8%36%5%24446%40%
1261
16th to endNight
7%316%7%35%5%6%9%42%
1260
July1st to 15thNight
3315%314336%63%
1260
16th to endNight
4212323336%67%
1446
August1st to 15thNight
4213322347%65%
1561
16th to endNight
4313424447%59%
1757
September1st to 15thNight
5%213324335%63%
1750
16th to endNight
10%6%25%6%35%6%6%7%37%
1817
October1st to 15thNight
10%8%47%8%45%45%6%34%
1980
16th to endNight
11%9%38%7%5%6%6%6%8%25%
2166
November1st to 15thNight
12%13%49%9%5%8%6%5%5%18%
2450
16th to endNight
8%11%5%10%8%5%7%6%7%8%20%
2520
December1st to 15thNight
7%13%5%8%9%48%7%6%7%22%
2544
16th to endNight
9%16%49%8%48%7%7%6%16%
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
64%11%7%7%6%2
1253
16th to endDay
63%8%9%9%6%2
1557
February1st to 15thDay
68%9%10%6%41
1576
16th to endDay
66%7%9%11%4
1427
March1st to 15thDay
70%9%10%7%2
1923
16th to endDay
78%5%6%8%
2133
April1st to 15thDay
72%7%9%7%2
2149
16th to endDay
70%6%8%10%3
2340
May1st to 15thDay
58%8%11%14%6%
2510
16th to endDay
68%7%12%10%2
2619
June1st to 15thDay
62%8%14%9%4
2697
16th to endDay
61%7%13%12%3
2700
July1st to 15thDay
36%7%13%26%14%1
2541
16th to endDay
30%7%16%26%15%2
2554
August1st to 15thDay
34%8%16%25%13%2
2380
16th to endDay
37%8%15%27%10%1
2444
September1st to 15thDay
32%5%13%23%22%3
2097
16th to endDay
48%7%14%14%11%3
1810
October1st to 15thDay
55%8%11%16%6%
1650
16th to endDay
58%8%13%13%6%
1703
November1st to 15thDay
72%7%9%6%21
1408
16th to endDay
67%8%411%6%1
1440
December1st to 15thDay
62%8%10%12%5%
1413
16th to endDay
67%12%6%8%4
1344
January1st to 15thNight
59%13%8%9%7%1
2686
16th to endNight
57%10%10%9%7%4
2666
February1st to 15thNight
63%10%10%8%5%1
2288
16th to endNight
64%8%9%12%4
2047
March1st to 15thNight
63%12%11%10%2
2034
16th to endNight
68%9%10%9%2
2091
April1st to 15thNight
62%8%12%12%3
1796
16th to endNight
55%8%11%15%8%
1620
May1st to 15thNight
48%8%14%19%7%1
1440
16th to endNight
49%10%18%16%3
1496
June1st to 15thNight
46%9%19%17%6%
1261
16th to endNight
38%11%21%21%42
1260
July1st to 15thNight
22%7%18%31%16%4
1190
16th to endNight
18%6%18%32%18%4
1352
August1st to 15thNight
20%8%16%33%15%4
1553
16th to endNight
25%7%18%31%14%3
1757
September1st to 15thNight
23%6%14%24%24%6%
1750
16th to endNight
45%8%11%15%15%4
1817
October1st to 15thNight
50%6%11%19%10%
1980
16th to endNight
57%8%13%11%8%
2166
November1st to 15thNight
68%9%9%8%22
2450
16th to endNight
62%10%9%6%7%1
2520
December1st to 15thNight
60%13%9%10%6%
2544
16th to endNight
68%11%7%7%41
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
8%10%20%28%25%8%
60
16th to endDay
22%21%29%17%8%
124
February1st to 15thDay
20%27%33%13%3
236
16th to endDay
21%30%27%16%2
213
March1st to 15thDay
27%36%27%8%
270
16th to endDay
29%32%29%5%1
288
April1st to 15thDay
26%24%29%13%4
269
16th to endDay
35%22%25%13%21
270
May1st to 15thDay
32%19%25%17%31
288
16th to endDay
28%14%27%18%6%4
330
June1st to 15thDay
26%18%25%20%6%1
492
16th to endDay
21%16%33%18%9%1
495
July1st to 15thDay
13%8%31%32%12%2
475
16th to endDay
10%7%33%31%10%5%
392
August1st to 15thDay
11%7%26%33%13%6%
315
16th to endDay
8%12%29%31%12%5%
332
September1st to 15thDay
14%8%31%31%11%2
294
16th to endDay
16%16%36%22%5%1
255
October1st to 15thDay
23%19%30%18%6%
255
16th to endDay
21%21%32%17%41
228
November1st to 15thDay
16%33%40%10%
60
16th to endDay
30%11%25%11%318%
60
December1st to 15thDay
25%16%41%13%3
60
16th to endDay
15%12%45%14%10%1
64
January1st to 15thNight
16%21%27%18%13%2
750
16th to endNight
15%17%32%18%12%4
774
February1st to 15thNight
13%15%38%24%6%
704
16th to endNight
13%16%35%24%8%
632
March1st to 15thNight
14%21%40%15%7%1
720
16th to endNight
13%19%40%20%5%1
768
April1st to 15thNight
11%14%38%24%9%1
716
16th to endNight
11%7%41%26%10%2
540
May1st to 15thNight
11%5%29%32%16%5%
360
16th to endNight
11%322%36%24%1
375
June1st to 15thNight
12%6%24%32%21%3
360
16th to endNight
6%428%35%21%2
360
July1st to 15thNight
3214%35%39%3
340
16th to endNight
3211%34%39%6%
376
August1st to 15thNight
5%8%30%39%15%
479
16th to endNight
5%217%27%37%8%
611
September1st to 15thNight
6%118%30%31%12%
700
16th to endNight
14%428%26%21%5%
656
October1st to 15thNight
14%8%29%24%19%4
660
16th to endNight
16%10%38%19%9%4
704
November1st to 15thNight
19%20%38%17%4
700
16th to endNight
14%21%35%14%8%5%
720
December1st to 15thNight
14%16%37%22%8%1
724
16th to endNight
17%23%37%14%7%
800
Page generated at 2017-09-11 16:35:14. Version ac04

Copyright 2017 A. Danko


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