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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 2018-03-11.

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
36%
15288
10%
49044
8%
15259
38%
15259
15%
36573

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%
825
8%
2911
7%
821
32%
821
9%
2367
January16th to endNight
26%
841
8%
2888
7%
841
29%
841
11%
2251
February1st to 15thNight
23%
760
7%
2483
4%
760
27%
760
9%
2023
February16th to endNight
23%
684
9%
2215
7%
684
27%
684
9%
1817
March1st to 15thNight
19%
764
5%
2160
3%
764
21%
764
9%
1813
March16th to endNight
18%
768
5%
2091
2%
768
20%
768
8%
1788
April1st to 15thNight
26%
716
6%
1796
3%
716
27%
716
12%
1485
April16th to endNight
31%
540
10%
1620
6%
540
34%
540
15%
1244
May1st to 15thNight
46%
359
11%
1439
16%
359
49%
359
15%
980
May16th to endNight
52%
375
7%
1496
9%
374
56%
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
79%
376
18%
1352
27%
354
83%
354
44%
613
August1st to 15thNight
79%
479
18%
1553
20%
477
81%
477
42%
794
August16th to endNight
67%
611
24%
1757
19%
611
70%
611
41%
978
September1st to 15thNight
68%
720
24%
1800
14%
720
71%
720
48%
1038
September16th to endNight
47%
716
18%
1983
13%
716
49%
716
23%
1413
October1st to 15thNight
41%
720
11%
2160
10%
720
44%
720
20%
1529
October16th to endNight
29%
768
10%
2363
7%
768
34%
768
14%
1811
November1st to 15thNight
16%
760
6%
2660
4%
760
19%
760
7%
2214
November16th to endNight
20%
780
5%
2730
3%
780
23%
780
8%
2223
December1st to 15thNight
28%
786
7%
2756
5%
786
31%
786
10%
2199
December16th to endNight
15%
880
6%
3120
4%
880
18%
880
6%
2669

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%45%26%
49607
Night
8%11%49%8%46%5%5%6%27%
49200
Cloud CoverDay
12%12%47%6%35%5%5%6%28%
49607
Night
8%10%47%7%46%6%6%7%31%
49203
TransparencyDay
57%8%11%14%7%1
49266
Night
53%9%12%14%8%2
49045
SeeingDay
21%18%30%20%7%2
6639
Night
13%12%31%23%15%3
15293

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
11%15%6%10%10%5%8%6%4416%
1358
16th to endDay
10%19%5%10%7%47%5%5%6%17%
1687
February1st to 15thDay
10%17%6%13%9%5%7%5%5%6%13%
1711
16th to endDay
8%20%8%11%9%46%5%4416%
1544
March1st to 15thDay
6%21%8%10%9%5%8%6%4413%
2033
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%54%
2160
16th to endDay
13%10%38%6%445%45%33%
1974
October1st to 15thDay
13%12%49%7%345%5%6%27%
1800
16th to endDay
14%10%48%8%46%6%5%5%23%
1857
November1st to 15thDay
15%16%6%12%10%5%7%5%4411%
1528
16th to endDay
12%18%6%10%8%5%6%445%16%
1560
December1st to 15thDay
9%12%410%9%6%8%6%3422%
1531
16th to endDay
8%20%6%10%9%6%8%6%5%414%
1456
January1st to 15thNight
9%12%6%10%10%5%8%6%5%5%18%
2911
16th to endNight
11%11%5%11%9%47%6%6%6%19%
2888
February1st to 15thNight
9%14%6%12%10%5%5%5%46%17%
2471
16th to endNight
8%16%7%12%9%5%6%445%18%
2215
March1st to 15thNight
5%16%6%9%10%5%9%9%6%6%12%
2160
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%
1800
16th to endNight
10%6%37%8%46%6%6%6%34%
1983
October1st to 15thNight
10%8%5%8%7%35%5%5%5%32%
2160
16th to endNight
14%10%310%8%5%6%5%5%7%22%
2363
November1st to 15thNight
14%14%5%10%10%48%6%5%5%13%
2660
16th to endNight
10%16%5%9%10%5%8%6%5%5%15%
2730
December1st to 15thNight
6%14%6%9%10%6%8%6%5%5%20%
2756
16th to endNight
9%19%6%12%9%5%8%6%5%413%
3120

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%9%7%46%6%6%8%19%
1358
16th to endDay
10%16%48%8%46%5%5%8%20%
1687
February1st to 15thDay
10%16%5%10%9%5%6%5%6%6%16%
1711
16th to endDay
9%19%6%9%8%36%5%5%6%18%
1544
March1st to 15thDay
6%19%6%10%8%46%6%6%6%17%
2033
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%
2160
16th to endDay
14%7%37%5%345%5%6%35%
1974
October1st to 15thDay
12%10%48%6%345%5%7%30%
1800
16th to endDay
12%10%37%7%45%7%7%8%26%
1857
November1st to 15thDay
12%14%6%10%9%5%7%5%6%6%14%
1528
16th to endDay
10%17%48%8%5%7%6%6%6%18%
1560
December1st to 15thDay
8%13%47%7%5%7%5%7%7%25%
1531
16th to endDay
7%17%5%9%8%5%6%7%7%6%16%
1456
January1st to 15thNight
8%11%5%8%8%5%7%7%7%8%22%
2910
16th to endNight
9%11%47%8%46%7%7%7%24%
2888
February1st to 15thNight
9%14%410%8%5%6%5%6%7%20%
2471
16th to endNight
8%14%8%9%7%5%6%5%6%6%20%
2215
March1st to 15thNight
414%49%8%48%7%9%9%18%
2160
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%
1800
16th to endNight
10%6%26%6%36%6%6%7%37%
1983
October1st to 15thNight
9%8%37%8%45%45%6%35%
2160
16th to endNight
11%9%38%7%5%6%6%6%8%27%
2363
November1st to 15thNight
11%13%49%8%48%6%6%6%19%
2660
16th to endNight
8%12%410%8%5%7%6%7%8%20%
2730
December1st to 15thNight
6%12%5%8%9%48%7%6%7%23%
2756
16th to endNight
9%15%49%8%48%7%7%6%17%
3120

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%8%6%1
1358
16th to endDay
63%8%9%9%6%2
1687
February1st to 15thDay
68%9%10%6%41
1711
16th to endDay
66%7%9%12%4
1544
March1st to 15thDay
68%9%10%8%2
2033
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
2160
16th to endDay
49%7%14%13%11%3
1974
October1st to 15thDay
54%8%11%17%6%
1800
16th to endDay
56%8%12%13%7%1
1857
November1st to 15thDay
71%7%9%6%21
1528
16th to endDay
67%9%410%5%1
1560
December1st to 15thDay
60%8%10%13%6%1
1531
16th to endDay
67%11%6%7%5%
1456
January1st to 15thNight
60%12%8%8%7%1
2911
16th to endNight
58%10%10%9%6%4
2888
February1st to 15thNight
63%9%9%9%5%1
2483
16th to endNight
65%8%8%12%3
2215
March1st to 15thNight
62%12%11%10%3
2160
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%25%24%6%
1800
16th to endNight
45%8%11%15%14%4
1983
October1st to 15thNight
49%6%12%19%11%
2160
16th to endNight
56%8%12%11%10%1
2363
November1st to 15thNight
66%9%10%8%22
2660
16th to endNight
62%11%10%6%7%1
2730
December1st to 15thNight
58%12%9%10%6%1
2756
16th to endNight
68%11%6%7%41
3120

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
13%10%21%23%24%7%
90
16th to endDay
23%25%27%16%6%
161
February1st to 15thDay
21%25%34%13%3
281
16th to endDay
19%33%28%15%2
252
March1st to 15thDay
25%33%28%10%1
312
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
13%7%31%33%11%2
315
16th to endDay
19%15%34%20%7%1
315
October1st to 15thDay
22%20%30%18%7%1
315
16th to endDay
19%21%29%18%8%2
286
November1st to 15thDay
20%28%38%10%2
90
16th to endDay
30%13%31%11%212%
90
December1st to 15thDay
17%12%31%17%15%5%
90
16th to endDay
15%10%48%16%7%1
96
January1st to 15thNight
17%19%27%18%14%3
825
16th to endNight
16%17%33%17%11%3
841
February1st to 15thNight
15%15%38%23%6%1
764
16th to endNight
14%16%36%24%7%
684
March1st to 15thNight
14%21%38%16%8%1
764
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
5%118%30%30%12%
720
16th to endNight
14%427%28%21%5%
716
October1st to 15thNight
14%7%29%25%20%3
720
16th to endNight
16%10%37%19%11%4
768
November1st to 15thNight
19%19%38%17%4
760
16th to endNight
15%20%36%13%8%5%
780
December1st to 15thNight
13%14%34%22%11%2
786
16th to endNight
17%22%38%15%6%
880
Page generated at 2018-03-12 10:28:04. Version ac04

Copyright 2018 A. Danko


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