Knudson Forestry Service Road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Knudson Forestry Service Road clear sky chart from 2005-11-05 to 2017-09-24.

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%
14654
10%
46791
8%
14627
43%
14627
17%
33324

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
25%
739
6%
2637
5%
737
27%
737
7%
2194
January16th to endNight
33%
768
8%
2688
8%
768
34%
768
11%
2052
February1st to 15thNight
33%
697
5%
2348
6%
697
34%
697
9%
1897
February16th to endNight
40%
632
12%
1988
10%
632
44%
632
15%
1458
March1st to 15thNight
29%
720
6%
2133
4%
720
32%
720
12%
1630
March16th to endNight
31%
768
8%
2019
4%
768
34%
768
14%
1585
April1st to 15thNight
39%
719
6%
1799
2%
719
41%
719
17%
1372
April16th to endNight
40%
503
9%
1583
7%
503
43%
503
16%
1137
May1st to 15thNight
50%
359
11%
1439
15%
359
54%
359
19%
902
May16th to endNight
52%
375
7%
1496
10%
374
53%
374
17%
994
June1st to 15thNight
45%
360
3%
1248
1%
360
45%
360
19%
841
June16th to endNight
47%
360
6%
1172
1%
360
48%
360
26%
733
July1st to 15thNight
65%
340
8%
1190
5%
340
66%
340
38%
584
July16th to endNight
65%
376
15%
1414
21%
354
71%
354
46%
583
August1st to 15thNight
79%
360
19%
1432
28%
358
83%
358
43%
632
August16th to endNight
62%
646
21%
1792
16%
646
65%
646
41%
1024
September1st to 15thNight
60%
720
22%
1800
11%
720
63%
720
43%
1062
September16th to endNight
52%
692
19%
1883
13%
692
54%
692
27%
1242
October1st to 15thNight
46%
660
13%
1980
12%
660
49%
660
22%
1340
October16th to endNight
38%
704
9%
2241
8%
704
41%
704
14%
1643
November1st to 15thNight
26%
700
8%
2411
7%
700
29%
700
9%
1937
November16th to endNight
32%
720
6%
2520
4%
720
35%
720
10%
1975
December1st to 15thNight
32%
868
7%
2668
5%
868
34%
868
10%
2156
December16th to endNight
25%
868
6%
2910
4%
868
28%
868
8%
2351

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
8%9%48%7%46%5%6%7%32%
48138
Night
6%9%48%7%46%5%6%8%33%
46948
Cloud CoverDay
8%10%47%7%45%5%5%7%33%
48138
Night
7%10%47%6%35%5%6%8%33%
46951
TransparencyDay
49%9%14%16%8%1
47798
Night
47%10%16%17%6%1
46792
SeeingDay
17%18%31%20%9%2
6010
Night
13%10%27%29%16%2
14664

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
7%10%6%12%10%48%7%7%7%18%
1300
16th to endDay
6%12%6%9%7%35%5%6%8%27%
1536
February1st to 15thDay
414%7%14%10%46%7%6%7%17%
1513
16th to endDay
311%6%13%10%5%5%6%6%8%23%
1485
March1st to 15thDay
5%14%6%10%9%5%7%5%7%6%20%
1824
16th to endDay
6%14%6%11%9%5%8%5%7%8%16%
2204
April1st to 15thDay
8%13%6%9%8%5%7%6%5%7%21%
2149
16th to endDay
7%13%5%9%7%47%6%6%8%23%
2374
May1st to 15thDay
8%9%46%7%45%5%6%7%33%
2511
16th to endDay
12%9%37%8%47%5%6%8%24%
2615
June1st to 15thDay
14%7%47%7%46%5%46%29%
2703
16th to endDay
12%6%36%7%345%5%7%35%
2781
July1st to 15thDay
5%31442445%7%54%
2700
16th to endDay
5%31232445%7%59%
2658
August1st to 15thDay
5%414425%5%6%7%52%
2520
16th to endDay
5%425%6%25%45%8%49%
2408
September1st to 15thDay
8%5%25%5%2434453%
2160
16th to endDay
12%8%37%5%345%5%8%35%
1935
October1st to 15thDay
9%12%47%6%446%5%6%32%
1650
16th to endDay
10%9%5%8%9%5%6%5%5%7%25%
1631
November1st to 15thDay
10%15%7%10%8%46%6%46%20%
1444
16th to endDay
5%13%6%9%8%46%7%6%8%23%
1440
December1st to 15thDay
5%13%6%11%9%6%6%5%7%6%21%
1277
16th to endDay
413%7%12%10%5%7%6%8%6%16%
1320
January1st to 15thNight
8%13%6%12%8%5%7%7%5%7%16%
2637
16th to endNight
5%13%6%9%8%46%6%7%9%21%
2688
February1st to 15thNight
5%13%6%13%9%47%6%5%6%20%
2336
16th to endNight
39%6%10%8%46%5%6%8%29%
1988
March1st to 15thNight
311%5%9%8%47%6%7%8%26%
2133
16th to endNight
5%11%5%8%9%46%6%7%7%27%
2015
April1st to 15thNight
49%5%8%8%46%7%7%8%29%
1799
16th to endNight
6%11%36%6%47%6%6%9%31%
1583
May1st to 15thNight
6%7%36%6%35%45%7%43%
1439
16th to endNight
7%6%36%5%36%6%7%8%37%
1496
June1st to 15thNight
8%7%35%6%46%6%6%7%36%
1248
16th to endNight
6%5%245%345%7%8%44%
1172
July1st to 15thNight
231232346%8%61%
1260
16th to endNight
32211235%7%67%
1509
August1st to 15thNight
22221445%7%65%
1440
16th to endNight
431442346%7%57%
1792
September1st to 15thNight
6%31332345%7%58%
1800
16th to endNight
8%6%25%4445%6%9%40%
1883
October1st to 15thNight
6%9%37%6%2445%7%41%
1980
16th to endNight
10%10%5%7%6%45%6%5%8%28%
2241
November1st to 15thNight
9%13%6%8%8%46%5%6%6%23%
2411
16th to endNight
6%13%6%10%9%46%6%5%8%21%
2520
December1st to 15thNight
414%7%10%9%5%6%6%6%7%21%
2668
16th to endNight
413%6%12%9%5%7%6%6%7%19%
2910

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%11%5%12%10%48%6%7%6%18%
1300
16th to endDay
7%13%6%9%7%345%6%8%27%
1536
February1st to 15thDay
5%15%7%12%10%47%5%6%7%17%
1513
16th to endDay
313%7%11%9%45%5%6%8%23%
1485
March1st to 15thDay
5%15%6%10%8%5%6%6%6%6%20%
1824
16th to endDay
7%15%6%9%9%5%7%6%6%8%17%
2204
April1st to 15thDay
9%14%5%9%8%5%7%5%6%7%21%
2149
16th to endDay
8%14%48%7%46%6%6%8%24%
2374
May1st to 15thDay
9%10%46%7%36%46%7%33%
2511
16th to endDay
14%8%38%8%46%5%6%8%25%
2615
June1st to 15thDay
15%9%36%7%45%45%6%30%
2703
16th to endDay
13%7%36%6%345%5%7%36%
2781
July1st to 15thDay
5%32343445%7%55%
2700
16th to endDay
5%313323446%60%
2658
August1st to 15thDay
5%4134245%6%6%53%
2520
16th to endDay
6%425%5%345%5%8%49%
2408
September1st to 15thDay
8%5%25%5%24335%53%
2160
16th to endDay
12%8%37%5%345%6%7%35%
1935
October1st to 15thDay
9%11%48%6%5%45%5%5%32%
1650
16th to endDay
12%9%49%8%36%5%48%26%
1631
November1st to 15thDay
11%17%6%9%7%45%5%5%5%20%
1444
16th to endDay
5%15%5%9%8%46%6%7%8%23%
1440
December1st to 15thDay
6%12%6%11%8%5%7%6%5%8%19%
1277
16th to endDay
5%14%7%12%9%5%7%6%8%7%16%
1320
January1st to 15thNight
9%15%6%11%9%47%6%5%7%16%
2636
16th to endNight
6%13%6%9%8%45%6%6%9%21%
2688
February1st to 15thNight
6%14%7%11%8%46%5%5%7%20%
2336
16th to endNight
410%7%10%7%46%45%8%30%
1988
March1st to 15thNight
412%5%9%7%45%6%8%9%25%
2133
16th to endNight
7%11%5%8%7%46%6%7%8%27%
2019
April1st to 15thNight
5%10%38%6%46%7%6%8%30%
1799
16th to endNight
7%10%36%6%5%6%5%6%8%32%
1583
May1st to 15thNight
7%7%35%6%35%447%44%
1439
16th to endNight
8%6%35%6%446%7%8%38%
1496
June1st to 15thNight
9%7%26%6%35%6%7%8%35%
1248
16th to endNight
7%5%245%25%46%9%44%
1172
July1st to 15thNight
232131445%8%62%
1260
16th to endNight
421112348%68%
1509
August1st to 15thNight
22121135%5%8%64%
1440
16th to endNight
5%31342445%7%57%
1792
September1st to 15thNight
6%41432235%7%59%
1800
16th to endNight
8%7%25%5%335%7%9%41%
1883
October1st to 15thNight
7%8%37%6%2435%7%41%
1980
16th to endNight
13%10%47%7%35%5%6%7%28%
2241
November1st to 15thNight
11%13%5%8%6%45%6%6%7%22%
2411
16th to endNight
7%14%6%10%8%46%5%5%8%22%
2520
December1st to 15thNight
6%14%6%10%9%5%6%5%5%7%21%
2668
16th to endNight
5%13%6%12%9%47%6%6%7%19%
2910

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
60%13%12%9%4
1300
16th to endDay
54%10%14%14%5%1
1536
February1st to 15thDay
62%12%12%7%4
1513
16th to endDay
57%8%15%12%4
1485
March1st to 15thDay
61%10%14%10%1
1824
16th to endDay
63%9%15%8%1
2204
April1st to 15thDay
62%9%13%12%1
2149
16th to endDay
55%10%17%12%4
2374
May1st to 15thDay
48%8%16%15%9%
2511
16th to endDay
56%9%17%14%2
2619
June1st to 15thDay
55%7%13%15%5%1
2703
16th to endDay
47%8%15%19%8%
2781
July1st to 15thDay
28%7%14%24%18%5%
2541
16th to endDay
24%6%15%27%21%4
2490
August1st to 15thDay
28%7%17%27%14%4
2503
16th to endDay
31%7%16%26%14%2
2408
September1st to 15thDay
34%5%12%24%20%2
2160
16th to endDay
46%7%14%17%10%3
1935
October1st to 15thDay
51%8%13%19%7%
1650
16th to endDay
55%9%14%16%3
1631
November1st to 15thDay
64%9%12%10%31
1444
16th to endDay
55%11%12%13%5%1
1440
December1st to 15thDay
59%12%13%11%3
1277
16th to endDay
63%12%12%10%2
1320
January1st to 15thNight
64%12%9%9%3
2637
16th to endNight
56%11%13%13%42
2688
February1st to 15thNight
61%10%12%11%3
2348
16th to endNight
51%8%15%18%5%
1988
March1st to 15thNight
52%12%19%12%3
2133
16th to endNight
51%13%17%15%1
2019
April1st to 15thNight
50%10%19%16%3
1799
16th to endNight
48%9%20%17%3
1583
May1st to 15thNight
40%9%20%20%9%
1440
16th to endNight
43%10%20%20%3
1496
June1st to 15thNight
44%9%19%18%6%1
1248
16th to endNight
35%10%24%22%7%
1172
July1st to 15thNight
20%8%19%29%17%4
1190
16th to endNight
15%5%20%31%22%3
1414
August1st to 15thNight
17%6%22%31%17%4
1432
16th to endNight
25%7%20%29%14%2
1792
September1st to 15thNight
25%7%15%28%19%3
1800
16th to endNight
37%9%16%22%9%3
1883
October1st to 15thNight
42%9%16%21%10%
1980
16th to endNight
51%9%16%19%4
2241
November1st to 15thNight
57%14%12%11%31
2411
16th to endNight
58%10%12%11%41
2520
December1st to 15thNight
61%10%11%14%2
2668
16th to endNight
61%10%14%10%2
2910

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
15%23%38%26%5%
60
16th to endDay
12%10%32%32%10%
64
February1st to 15thDay
19%16%34%23%5%1
173
16th to endDay
14%24%27%19%12%
223
March1st to 15thDay
30%26%28%12%1
270
16th to endDay
27%27%26%14%4
288
April1st to 15thDay
26%21%32%11%6%1
269
16th to endDay
22%26%28%13%5%2
270
May1st to 15thDay
21%22%33%13%7%2
288
16th to endDay
23%13%27%18%12%4
330
June1st to 15thDay
17%18%35%16%9%2
498
16th to endDay
16%20%32%18%10%1
576
July1st to 15thDay
9%16%39%25%8%
475
16th to endDay
9%14%36%27%8%3
327
August1st to 15thDay
9%10%29%28%13%7%
315
16th to endDay
8%17%36%21%12%4
332
September1st to 15thDay
16%18%25%20%16%2
315
16th to endDay
18%16%28%21%12%2
288
October1st to 15thDay
22%17%29%19%8%2
255
16th to endDay
19%9%25%31%12%1
143
November1st to 15thDay
19%19%47%11%1
67
16th to endDay
6%11%33%20%15%13%
60
December1st to 15thDay
16%10%31%30%8%3
60
16th to endDay
14%143%28%10%1
64
January1st to 15thNight
19%13%30%22%11%1
741
16th to endNight
13%10%32%28%12%2
768
February1st to 15thNight
14%10%24%36%11%2
704
16th to endNight
9%12%26%29%19%2
632
March1st to 15thNight
15%14%33%25%10%1
720
16th to endNight
15%11%33%27%10%2
768
April1st to 15thNight
13%12%25%30%15%2
719
16th to endNight
14%12%25%32%12%1
503
May1st to 15thNight
9%8%23%34%20%2
360
16th to endNight
12%5%23%33%24%1
375
June1st to 15thNight
10%9%26%32%19%1
360
16th to endNight
8%8%30%31%20%1
360
July1st to 15thNight
5%6%19%39%27%2
340
16th to endNight
45%20%40%27%
376
August1st to 15thNight
3113%36%40%3
360
16th to endNight
8%5%21%32%29%3
646
September1st to 15thNight
9%5%20%26%28%10%
720
16th to endNight
14%6%22%27%23%5%
692
October1st to 15thNight
14%8%23%31%20%2
660
16th to endNight
19%10%23%28%15%1
704
November1st to 15thNight
21%11%35%23%7%1
700
16th to endNight
18%12%28%24%13%2
720
December1st to 15thNight
16%11%28%30%11%1
868
16th to endNight
12%12%37%29%7%
868
Page generated at 2017-09-25 06:02:27. Version ac04

Copyright 2017 A. Danko


Knudson Forestry Service Road Clear Sky Chart | Charts Home