Timber Point:
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Timber Point: clear sky chart from 2005-11-05 to 2017-09-22.

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%
14204
5%
46506
5%
14171
42%
14171
11%
36897

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
32%
855
4%
3052
4%
850
33%
850
6%
2593
January16th to endNight
34%
800
8%
3072
8%
800
36%
800
7%
2502
February1st to 15thNight
39%
731
8%
2554
8%
727
41%
727
10%
2045
February16th to endNight
50%
657
11%
2148
10%
657
51%
657
15%
1588
March1st to 15thNight
43%
720
12%
2160
11%
720
45%
720
15%
1674
March16th to endNight
46%
627
6%
2016
7%
627
47%
627
12%
1590
April1st to 15thNight
53%
539
7%
1679
6%
539
54%
539
17%
1215
April16th to endNight
51%
516
2%
1416
2%
516
51%
516
18%
1059
May1st to 15thNight
53%
359
0%
1158
0%
359
53%
359
16%
848
May16th to endNight
57%
374
0%
1023
0%
374
57%
374
25%
682
June1st to 15thNight
54%
221
0%
761
0%
221
54%
221
20%
517
June16th to endNight
56%
180
0%
720
0%
180
56%
180
13%
509
July1st to 15thNight
53%
196
0%
712
0%
196
53%
196
14%
509
July16th to endNight
46%
376
0%
1062
0%
354
46%
354
14%
808
August1st to 15thNight
54%
420
0%
1212
0%
418
54%
418
20%
861
August16th to endNight
35%
573
1%
1546
1%
573
35%
573
12%
1272
September1st to 15thNight
41%
540
6%
1752
5%
540
42%
540
13%
1336
September16th to endNight
34%
644
8%
1861
5%
644
36%
644
13%
1471
October1st to 15thNight
39%
660
8%
2060
8%
660
40%
660
13%
1594
October16th to endNight
36%
720
3%
2406
3%
720
37%
720
9%
1954
November1st to 15thNight
35%
730
4%
2629
3%
730
36%
730
7%
2228
November16th to endNight
33%
844
5%
2974
4%
844
34%
844
8%
2452
December1st to 15thNight
32%
930
5%
3077
4%
930
34%
930
7%
2648
December16th to endNight
36%
992
6%
3456
6%
992
37%
992
6%
2942

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%12%6%10%8%46%6%6%7%19%
48458
Night
9%14%6%10%8%46%5%6%7%19%
46610
TransparencyDay
61%8%15%12%2
48065
Night
62%7%14%12%3
46508
SeeingDay
17%9%22%24%18%5%
7626
Night
16%5%17%30%23%5%
14209

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
8%17%10%16%9%5%6%45%6%8%
898
16th to endDay
7%15%8%11%9%47%7%8%8%12%
1152
February1st to 15thDay
6%13%7%11%8%5%7%7%7%6%18%
1306
16th to endDay
411%8%10%9%6%6%6%7%10%20%
1326
March1st to 15thDay
212%7%11%11%7%8%6%5%7%19%
1800
16th to endDay
313%8%12%8%5%6%5%5%8%20%
2208
April1st to 15thDay
5%14%8%11%9%45%6%6%8%20%
2268
16th to endDay
413%6%10%10%5%6%5%5%7%24%
2544
May1st to 15thDay
10%15%7%7%6%46%5%5%6%23%
2792
16th to endDay
9%8%48%8%35%5%7%7%30%
3090
June1st to 15thDay
13%10%5%9%8%45%6%5%6%22%
3198
16th to endDay
14%10%5%10%9%47%6%6%7%18%
3240
July1st to 15thDay
17%8%5%9%8%5%7%7%7%7%16%
3201
16th to endDay
16%9%48%7%46%6%6%7%21%
3035
August1st to 15thDay
12%9%47%7%45%6%7%7%28%
2741
16th to endDay
25%11%48%6%35%5%5%5%16%
2656
September1st to 15thDay
21%10%48%7%45%5%6%6%18%
2205
16th to endDay
17%14%410%8%445%5%5%18%
1911
October1st to 15thDay
13%17%5%9%8%4445%7%19%
1570
16th to endDay
11%15%6%11%9%46%5%6%5%16%
1466
November1st to 15thDay
8%18%9%12%9%5%5%5%5%6%12%
1228
16th to endDay
6%15%6%15%10%47%5%8%7%12%
973
December1st to 15thDay
10%16%8%12%9%5%6%6%7%7%9%
882
16th to endDay
6%16%7%11%13%5%5%10%7%7%7%
768
January1st to 15thNight
8%18%9%12%11%5%6%45%5%13%
3052
16th to endNight
8%15%7%13%9%47%5%6%6%14%
3072
February1st to 15thNight
6%13%6%12%9%6%8%6%6%7%15%
2544
16th to endNight
310%7%12%8%45%5%7%7%25%
2148
March1st to 15thNight
313%7%11%7%47%6%45%26%
2160
16th to endNight
313%7%11%11%6%8%7%5%5%20%
2011
April1st to 15thNight
5%11%5%9%7%5%6%5%5%7%29%
1679
16th to endNight
5%11%5%8%9%5%7%7%7%7%25%
1416
May1st to 15thNight
9%10%48%6%46%5%7%7%28%
1157
16th to endNight
7%6%46%5%45%6%8%9%34%
1023
June1st to 15thNight
11%5%37%7%36%6%6%10%30%
761
16th to endNight
10%8%47%5%37%8%7%10%25%
720
July1st to 15thNight
14%6%37%8%47%7%10%9%20%
754
16th to endNight
16%8%46%7%37%7%7%8%23%
1134
August1st to 15thNight
11%6%26%6%346%8%9%32%
1218
16th to endNight
22%10%5%8%7%35%5%45%21%
1546
September1st to 15thNight
16%10%47%7%4445%7%25%
1752
16th to endNight
16%15%5%8%6%3445%5%24%
1861
October1st to 15thNight
13%16%37%7%34447%25%
2060
16th to endNight
11%20%7%9%7%4445%6%18%
2406
November1st to 15thNight
9%16%7%11%11%6%7%5%5%6%11%
2629
16th to endNight
7%14%9%15%9%5%7%5%6%7%12%
2974
December1st to 15thNight
8%20%8%10%10%5%6%5%5%8%9%
3077
16th to endNight
7%18%7%11%10%6%9%6%5%6%10%
3456

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
77%47%6%3
898
16th to endDay
65%7%13%11%2
1152
February1st to 15thDay
62%7%9%14%4
1306
16th to endDay
57%9%13%14%5%
1326
March1st to 15thDay
62%7%7%15%41
1800
16th to endDay
59%7%14%11%7%
2208
April1st to 15thDay
60%7%16%13%2
2268
16th to endDay
58%6%18%13%2
2544
May1st to 15thDay
60%7%15%13%3
2792
16th to endDay
49%8%16%21%4
3094
June1st to 15thDay
59%7%14%15%3
3198
16th to endDay
61%9%15%11%1
3240
July1st to 15thDay
61%10%16%9%1
3014
16th to endDay
58%10%20%10%
2844
August1st to 15thDay
51%9%21%14%2
2722
16th to endDay
67%9%16%6%
2656
September1st to 15thDay
62%10%14%10%2
2205
16th to endDay
66%7%13%11%1
1911
October1st to 15thDay
63%7%15%12%1
1570
16th to endDay
67%8%14%9%
1466
November1st to 15thDay
70%6%12%9%1
1228
16th to endDay
66%8%10%10%3
973
December1st to 15thDay
71%9%9%8%1
882
16th to endDay
69%8%7%10%3
768
January1st to 15thNight
72%6%9%7%3
3052
16th to endNight
66%7%10%11%2
3072
February1st to 15thNight
63%7%9%14%5%
2556
16th to endNight
54%6%15%15%6%
2148
March1st to 15thNight
58%6%9%16%7%1
2160
16th to endNight
62%6%13%9%7%
2016
April1st to 15thNight
51%7%16%20%3
1679
16th to endNight
52%8%18%17%3
1416
May1st to 15thNight
51%9%18%16%3
1158
16th to endNight
42%6%21%24%4
1023
June1st to 15thNight
44%9%23%18%3
761
16th to endNight
48%13%20%16%1
720
July1st to 15thNight
51%9%24%12%1
712
16th to endNight
54%9%22%12%
1062
August1st to 15thNight
43%13%23%17%2
1212
16th to endNight
64%7%16%10%
1546
September1st to 15thNight
57%7%19%14%1
1752
16th to endNight
60%6%16%14%1
1861
October1st to 15thNight
57%9%17%13%1
2060
16th to endNight
64%8%17%9%
2406
November1st to 15thNight
70%7%12%9%
2629
16th to endNight
68%6%11%11%1
2974
December1st to 15thNight
72%7%9%9%1
3077
16th to endNight
72%6%8%8%3
3456

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
21%6%15%30%17%8%
46
16th to endDay
12%14%21%29%17%4
64
February1st to 15thDay
12%8%27%30%15%5%
213
16th to endDay
6%6%28%26%21%10%
211
March1st to 15thDay
9%11%27%27%17%6%
240
16th to endDay
10%11%19%29%23%5%
281
April1st to 15thDay
11%11%27%23%20%6%
299
16th to endDay
12%11%27%23%21%3
450
May1st to 15thDay
17%12%20%24%16%8%
468
16th to endDay
12%9%20%25%24%7%
617
June1st to 15thDay
16%9%22%26%21%4
675
16th to endDay
18%7%19%26%22%5%
675
July1st to 15thDay
19%5%19%26%22%6%
636
16th to endDay
23%10%20%24%15%5%
515
August1st to 15thDay
15%10%20%24%21%7%
494
16th to endDay
31%12%23%20%10%2
505
September1st to 15thDay
32%12%24%14%11%5%
315
16th to endDay
25%10%25%19%14%4
278
October1st to 15thDay
25%12%27%21%8%4
225
16th to endDay
20%6%23%24%20%4
210
November1st to 15thDay
20%6%30%36%33
60
16th to endDay
5%330%30%16%15%
60
December1st to 15thDay
5%115%26%29%21%
57
16th to endDay
3315%37%31%9%
32
January1st to 15thNight
17%6%18%33%20%3
855
16th to endNight
14%8%22%32%18%2
800
February1st to 15thNight
12%6%20%38%19%2
734
16th to endNight
9%416%39%24%5%
657
March1st to 15thNight
9%7%21%30%26%4
720
16th to endNight
8%412%28%35%10%
627
April1st to 15thNight
7%413%31%35%7%
539
16th to endNight
9%418%30%28%8%
516
May1st to 15thNight
14%5%14%28%30%8%
360
16th to endNight
11%313%27%36%6%
375
June1st to 15thNight
15%216%31%29%4
221
16th to endNight
16%212%29%36%2
180
July1st to 15thNight
12%216%28%34%5%
196
16th to endNight
18%6%16%27%25%5%
376
August1st to 15thNight
15%216%27%31%6%
420
16th to endNight
29%6%17%20%21%4
573
September1st to 15thNight
22%5%17%28%21%4
540
16th to endNight
28%8%19%22%16%5%
644
October1st to 15thNight
23%8%17%32%14%3
660
16th to endNight
23%5%18%28%18%6%
720
November1st to 15thNight
19%418%31%19%6%
730
16th to endNight
15%5%19%29%25%5%
844
December1st to 15thNight
19%5%15%33%22%2
930
16th to endNight
14%6%17%33%20%7%
992
Page generated at 2017-09-23 03:43:34. Version ac04

Copyright 2017 A. Danko


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