Picketwire Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Picketwire Observatory clear sky chart from 2005-11-06 to 2024-01-12.

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%
24385
32%
74390
13%
24324
56%
24324
38%
36747

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 10thNight
33%
949
36%
2647
12%
946
56%
946
43%
1257
January11th to 20thNight
29%
778
37%
2411
15%
778
53%
778
37%
1106
January21st to endNight
30%
792
37%
2574
15%
792
54%
792
38%
1164
February1st to 10thNight
22%
720
35%
2284
9%
720
51%
720
34%
1077
February11th to 20thNight
19%
701
33%
2098
8%
700
44%
700
34%
1025
February21st to endNight
16%
592
42%
1776
6%
592
51%
592
33%
835
March1st to 10thNight
21%
720
31%
2160
6%
720
45%
720
32%
1047
March11th to 20thNight
29%
720
31%
1995
9%
720
46%
720
38%
1052
March21st to endNight
20%
658
37%
2044
8%
658
50%
658
30%
974
April1st to 10thNight
16%
540
33%
1800
7%
540
48%
540
32%
809
April11th to 20thNight
24%
533
31%
1777
11%
533
51%
533
30%
853
April21st to endNight
26%
540
29%
1800
10%
540
52%
540
30%
911
May1st to 10thNight
30%
540
27%
1764
12%
540
52%
540
30%
930
May11th to 20thNight
37%
531
21%
1545
12%
531
48%
531
29%
929
May21st to endNight
35%
584
27%
1552
9%
582
52%
582
41%
825
June1st to 10thNight
48%
540
28%
1440
13%
540
60%
540
42%
778
June11th to 20thNight
39%
540
30%
1440
13%
540
53%
540
49%
737
June21st to endNight
52%
540
23%
1440
13%
540
61%
540
38%
836
July1st to 10thNight
58%
525
20%
1400
13%
525
64%
525
33%
889
July11th to 20thNight
68%
522
23%
1392
16%
522
72%
522
43%
799
July21st to endNight
72%
591
13%
1641
13%
558
72%
558
27%
1036
August1st to 10thNight
70%
537
14%
1681
13%
534
72%
534
31%
966
August11th to 20thNight
64%
534
22%
1778
19%
534
70%
534
33%
983
August21st to endNight
62%
594
24%
1980
22%
594
68%
594
38%
1047
September1st to 10thNight
62%
540
30%
1800
24%
540
73%
540
39%
924
September11th to 20thNight
51%
540
37%
1831
24%
540
68%
540
47%
838
September21st to endNight
50%
540
35%
1980
25%
540
65%
540
41%
869
October1st to 10thNight
41%
670
32%
2110
15%
670
56%
670
41%
1024
October11th to 20thNight
42%
720
41%
2160
15%
720
64%
720
54%
923
October21st to endNight
39%
792
38%
2376
14%
792
57%
792
42%
1157
November1st to 10thNight
39%
919
39%
2399
13%
919
56%
919
54%
1125
November11th to 20thNight
35%
950
42%
2470
13%
950
55%
950
52%
1183
November21st to endNight
37%
950
38%
2470
12%
950
54%
950
47%
1251
December1st to 10thNight
31%
950
36%
2617
10%
950
52%
950
41%
1291
December11th to 20thNight
29%
950
36%
3102
11%
948
51%
948
36%
1415
December21st to endNight
25%
1043
23%
4656
9%
1026
48%
1026
26%
1882

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
44244345%6%8%56%
74761
Night
332332445%8%64%
74970
TransparencyDay
23%7%10%21%25%13%
74475
Night
19%5%10%23%28%14%
74778
SeeingDay
13%19%30%23%12%3
14223
Night
10%17%33%27%12%2
24391

By Month

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 10thDay
424212349%69%
1518
11th to 20thDay
1424323347%69%
1592
21st to endDay
133432335%6%67%
1782
February1st to 10thDay
1325%413448%64%
1674
11th to 20thDay
132332346%8%65%
1749
21st to endDay
15%35%33345%6%63%
1480
March1st to 10thDay
15%2433345%7%64%
1800
11th to 20thDay
37%3442446%8%54%
1962
21st to endDay
26%2442446%10%57%
2312
April1st to 10thDay
25%133245%6%9%59%
2160
11th to 20thDay
5%6%135%25%5%6%8%54%
2131
21st to endDay
5%7%2443447%9%51%
2160
May1st to 10thDay
5%6%234345%6%9%53%
2196
11th to 20thDay
7%6%34436%6%7%8%45%
2346
21st to endDay
5%424425%5%7%9%53%
2724
June1st to 10thDay
3313436%7%8%10%51%
2520
11th to 20thDay
33134246%6%9%60%
2520
21st to endDay
4414437%8%9%9%46%
2520
July1st to 10thDay
6%4245%47%8%9%11%42%
2520
11th to 20thDay
4325%5%46%7%8%11%45%
2520
21st to endDay
7%425%8%48%8%9%11%33%
2576
August1st to 10thDay
8%426%6%46%8%7%10%40%
2247
11th to 20thDay
7%4245%46%7%8%9%44%
2123
21st to endDay
6%325%5%46%6%7%9%46%
2376
September1st to 10thDay
6%425%5%35%5%8%8%48%
2160
11th to 20thDay
5%323325%5%5%7%60%
2129
21st to endDay
5%313423446%64%
1980
October1st to 10thDay
6%42433445%7%59%
1846
11th to 20thDay
2212212346%75%
1800
21st to endDay
5%42331224469%
1967
November1st to 10thDay
1212113448%73%
1673
11th to 20thDay
121432445%7%68%
1710
21st to endDay
15%2432335%7%65%
1710
December1st to 10thDay
334312347%70%
1558
11th to 20thDay
142332345%8%64%
1926
21st to endDay
1326%324347%66%
2794
January1st to 10thNight
132331235%7%69%
2647
11th to 20thNight
1323323347%69%
2411
21st to endNight
323423446%68%
2574
February1st to 10thNight
1424424437%67%
2284
11th to 20thNight
1325%32335%7%66%
2098
21st to endNight
424423246%70%
1776
March1st to 10thNight
1423324447%67%
2160
11th to 20thNight
25%2442345%8%61%
1995
21st to endNight
242331345%7%66%
2044
April1st to 10thNight
2422323347%69%
1800
11th to 20thNight
3414423347%64%
1777
21st to endNight
45%2332445%7%61%
1800
May1st to 10thNight
36%33325%447%60%
1764
11th to 20thNight
8%6%25%335%5%6%9%49%
1545
21st to endNight
5%41232345%8%65%
1552
June1st to 10thNight
232243446%10%60%
1440
11th to 20thNight
22122345%5%9%65%
1440
21st to endNight
5%323335%6%7%11%52%
1440
July1st to 10thNight
43245%38%6%7%11%46%
1440
11th to 20thNight
4323427%6%7%9%53%
1440
21st to endNight
5%4245%37%7%10%12%40%
1738
August1st to 10thNight
32135%47%7%9%9%49%
1690
11th to 20thNight
6%324436%5%8%11%48%
1778
21st to endNight
5%3234345%8%11%53%
1980
September1st to 10thNight
6%313425%6%7%10%54%
1800
11th to 20thNight
5%312313348%66%
1831
21st to endNight
4412313346%69%
1980
October1st to 10thNight
5%423213246%68%
2110
11th to 20thNight
2212222335%77%
2160
21st to endNight
3424323335%68%
2376
November1st to 10thNight
1212212346%76%
2399
11th to 20thNight
1213322235%76%
2470
21st to endNight
242332345%6%68%
2470
December1st to 10thNight
21332446%8%66%
2617
11th to 20thNight
131432335%8%68%
3271
21st to endNight
132442345%7%66%
4873

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 10thDay
15%37%29%35%10%
1519
11th to 20thDay
17%38%25%35%11%
1592
21st to endDay
18%38%24%33%14%
1782
February1st to 10thDay
20%39%27%27%14%
1674
11th to 20thDay
17%48%26%30%15%
1759
21st to endDay
21%5%6%16%30%22%
1480
March1st to 10thDay
19%5%7%23%29%17%
1800
11th to 20thDay
26%48%22%31%9%
1962
21st to endDay
23%410%24%28%10%
2312
April1st to 10thDay
21%6%9%23%25%17%
2160
11th to 20thDay
26%6%7%24%22%15%
2134
21st to endDay
27%7%11%21%26%9%
2160
May1st to 10thDay
26%8%11%21%24%10%
2196
11th to 20thDay
32%9%14%20%16%8%
2350
21st to endDay
25%8%11%18%23%15%
2724
June1st to 10thDay
24%10%12%21%20%13%
2520
11th to 20thDay
19%7%11%17%21%25%
2520
21st to endDay
28%9%12%19%19%14%
2520
July1st to 10thDay
31%12%14%14%16%13%
2451
11th to 20thDay
27%11%15%26%15%6%
2445
21st to endDay
38%15%19%20%7%1
2433
August1st to 10thDay
37%12%18%13%13%8%
2232
11th to 20thDay
31%11%13%20%18%8%
2123
21st to endDay
30%11%12%19%22%6%
2376
September1st to 10thDay
30%8%10%21%21%10%
2160
11th to 20thDay
21%7%11%17%26%18%
2129
21st to endDay
21%5%9%19%33%13%
1980
October1st to 10thDay
25%6%9%21%26%13%
1846
11th to 20thDay
12%36%19%36%24%
1800
21st to endDay
19%36%22%34%16%
1967
November1st to 10thDay
11%45%23%36%22%
1673
11th to 20thDay
15%37%26%35%14%
1710
21st to endDay
19%36%17%34%21%
1710
December1st to 10thDay
15%410%27%31%14%
1558
11th to 20thDay
19%410%22%31%14%
1924
21st to endDay
18%39%23%31%17%
2794
January1st to 10thNight
15%38%27%34%12%
2647
11th to 20thNight
17%38%26%32%15%
2411
21st to endNight
17%47%25%36%11%
2574
February1st to 10thNight
19%47%29%27%14%
2284
11th to 20thNight
20%310%27%28%12%
2098
21st to endNight
18%35%20%36%18%
1776
March1st to 10thNight
18%48%23%33%14%
2160
11th to 20thNight
22%410%22%32%10%
1995
21st to endNight
19%48%26%33%9%
2044
April1st to 10thNight
17%48%28%28%15%
1800
11th to 20thNight
22%48%26%27%13%
1777
21st to endNight
23%7%13%25%24%9%
1800
May1st to 10thNight
24%7%9%24%25%11%
1764
11th to 20thNight
31%8%14%21%18%8%
1546
21st to endNight
18%7%15%19%24%17%
1552
June1st to 10thNight
18%9%14%23%20%17%
1440
11th to 20thNight
16%6%10%18%26%24%
1440
21st to endNight
23%10%12%17%22%14%
1440
July1st to 10thNight
29%13%14%15%16%13%
1400
11th to 20thNight
23%9%18%29%13%8%
1392
21st to endNight
29%17%25%21%7%1
1641
August1st to 10thNight
25%14%24%16%13%8%
1681
11th to 20thNight
27%10%19%26%12%7%
1778
21st to endNight
22%11%17%26%20%5%
1980
September1st to 10thNight
22%8%14%26%21%9%
1800
11th to 20thNight
18%5%13%19%29%17%
1831
21st to endNight
18%5%9%23%32%13%
1980
October1st to 10thNight
19%5%11%21%28%16%
2110
11th to 20thNight
10%47%17%40%22%
2160
21st to endNight
20%46%24%30%17%
2376
November1st to 10thNight
12%26%22%36%21%
2399
11th to 20thNight
13%25%27%35%17%
2470
21st to endNight
17%37%21%32%20%
2470
December1st to 10thNight
16%5%9%30%29%12%
2617
11th to 20thNight
17%39%22%36%14%
3272
21st to endNight
18%411%23%28%16%
4873

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 10thDay
19%21%30%17%12%
270
11th to 20thDay
19%27%29%20%41
243
21st to endDay
12%25%37%18%8%
264
February1st to 10thDay
18%31%35%13%31
240
11th to 20thDay
23%28%31%13%5%
240
21st to endDay
30%29%30%10%1
198
March1st to 10thDay
23%28%26%20%3
240
11th to 20thDay
20%28%34%14%41
402
21st to endDay
28%36%26%8%2
462
April1st to 10thDay
21%35%30%10%41
420
11th to 20thDay
25%35%27%10%2
412
21st to endDay
21%36%28%14%1
420
May1st to 10thDay
17%29%37%12%5%1
459
11th to 20thDay
12%20%35%23%9%2
625
21st to endDay
12%21%34%20%11%2
679
June1st to 10thDay
6%16%28%32%15%4
630
11th to 20thDay
7%16%36%24%13%3
630
21st to endDay
7%12%35%27%15%5%
630
July1st to 10thDay
6%7%24%33%23%6%
621
11th to 20thDay
6%417%34%30%10%
618
21st to endDay
8%416%36%27%8%
518
August1st to 10thDay
10%5%22%35%20%7%
447
11th to 20thDay
5%7%30%36%17%5%
437
21st to endDay
6%6%30%35%17%5%
495
September1st to 10thDay
6%9%29%33%18%4
450
11th to 20thDay
7%11%33%32%13%3
419
21st to endDay
11%14%30%22%17%5%
270
October1st to 10thDay
16%17%26%22%13%6%
270
11th to 20thDay
13%21%29%23%10%4
270
21st to endDay
16%20%30%22%11%1
297
November1st to 10thDay
15%19%33%21%11%
270
11th to 20thDay
11%23%30%23%11%2
270
21st to endDay
14%20%36%18%9%3
270
December1st to 10thDay
16%28%33%17%6%1
270
11th to 20thDay
14%26%32%21%6%1
270
21st to endDay
23%29%32%13%4
297
January1st to 10thNight
11%20%33%24%9%2
950
11th to 20thNight
13%22%33%22%9%2
778
21st to endNight
6%23%37%24%8%1
792
February1st to 10thNight
10%25%42%20%4
720
11th to 20thNight
13%25%41%17%5%
704
21st to endNight
13%27%42%16%2
592
March1st to 10thNight
14%28%35%19%41
720
11th to 20thNight
10%19%39%24%7%1
720
21st to endNight
15%26%37%19%3
658
April1st to 10thNight
12%26%44%15%3
540
11th to 20thNight
12%24%37%22%5%
533
21st to endNight
14%21%38%20%7%
540
May1st to 10thNight
10%18%37%28%6%1
540
11th to 20thNight
13%15%31%29%11%2
531
21st to endNight
9%17%36%27%10%1
584
June1st to 10thNight
412%31%35%16%2
540
11th to 20thNight
314%40%33%10%1
540
21st to endNight
5%7%31%33%22%2
540
July1st to 10thNight
7%323%34%29%3
525
11th to 20thNight
4318%38%32%5%
522
21st to endNight
7%210%35%39%7%
591
August1st to 10thNight
4414%38%35%5%
537
11th to 20thNight
7%316%42%29%3
534
21st to endNight
5%421%36%30%5%
594
September1st to 10thNight
6%421%40%23%5%
540
11th to 20thNight
8%6%32%32%20%3
540
21st to endNight
7%13%25%36%16%2
540
October1st to 10thNight
8%15%33%29%13%2
670
11th to 20thNight
5%17%35%28%12%3
720
21st to endNight
11%17%31%25%13%4
792
November1st to 10thNight
10%15%34%29%11%1
919
11th to 20thNight
9%17%37%26%9%2
950
21st to endNight
10%16%35%27%10%1
950
December1st to 10thNight
11%20%37%24%7%1
950
11th to 20thNight
13%22%35%23%7%1
950
21st to endNight
13%22%36%23%41
1045
Page generated at 2024-01-09 05:14:43. Version ac07

Copyright 2024 Attilla Danko


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