Thousand Palms
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Thousand Palms clear sky chart from 2005-11-05 to 2017-09-19.

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
74%
16140
40%
46985
31%
16100
82%
16100
68%
19947

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
74%
717
34%
2327
32%
716
82%
716
54%
1019
January16th to endNight
67%
768
39%
2349
30%
768
79%
768
51%
1103
February1st to 15thNight
68%
699
39%
2107
31%
698
81%
698
59%
938
February16th to endNight
62%
632
37%
1895
34%
632
72%
632
54%
896
March1st to 15thNight
64%
720
36%
2140
29%
720
76%
720
64%
923
March16th to endNight
64%
768
38%
2073
25%
768
76%
768
67%
937
April1st to 15thNight
55%
719
38%
1799
16%
719
68%
719
65%
863
April16th to endNight
60%
718
42%
1798
17%
718
72%
718
77%
801
May1st to 15thNight
66%
539
43%
1619
27%
539
75%
539
79%
604
May16th to endNight
61%
562
40%
1685
26%
561
70%
561
80%
621
June1st to 15thNight
69%
540
36%
1620
27%
540
74%
540
83%
592
June16th to endNight
82%
540
38%
1620
32%
540
84%
540
85%
597
July1st to 15thNight
90%
510
33%
1530
28%
510
91%
510
74%
612
July16th to endNight
91%
564
36%
1593
30%
531
92%
531
64%
698
August1st to 15thNight
92%
717
38%
1790
25%
713
93%
713
82%
798
August16th to endNight
92%
764
45%
1910
31%
764
92%
764
78%
877
September1st to 15thNight
91%
720
40%
1890
31%
720
93%
720
77%
831
September16th to endNight
86%
671
49%
1856
41%
671
92%
671
87%
724
October1st to 15thNight
74%
660
46%
1815
35%
660
84%
660
78%
756
October16th to endNight
81%
704
46%
2118
42%
704
88%
704
77%
815
November1st to 15thNight
78%
700
40%
2275
36%
700
88%
700
71%
865
November16th to endNight
78%
720
43%
2340
43%
720
85%
720
67%
916
December1st to 15thNight
71%
720
37%
2340
33%
720
81%
720
54%
1026
December16th to endNight
63%
768
36%
2496
31%
768
73%
768
49%
1135

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
111112235%78%
47822
Night
11112235%80%
47186
TransparencyDay
9%35%13%25%42%
47518
Night
9%36%14%26%39%
46991
SeeingDay
210%24%34%20%6%
5843
Night
1319%34%33%8%
16150

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 15thDay
111213346%71%
1611
16th to endDay
221312346%69%
1872
February1st to 15thDay
2111212336%73%
1751
16th to endDay
121313448%67%
1579
March1st to 15thDay
1112338%76%
1818
16th to endDay
112248%76%
2148
April1st to 15thDay
111111247%75%
2149
16th to endDay
112485%
2160
May1st to 15thDay
1112485%
2331
16th to endDay
113386%
2429
June1st to 15thDay
1111487%
2340
16th to endDay
11289%
2340
July1st to 15thDay
211212345%74%
2340
16th to endDay
1112213447%69%
2464
August1st to 15thDay
1112245%79%
2160
16th to endDay
11111233479%
2292
September1st to 15thDay
11113335%77%
2070
16th to endDay
1121287%
1849
October1st to 15thDay
112235%81%
1815
16th to endDay
1133482%
1752
November1st to 15thDay
1111222480%
1584
16th to endDay
1112345%76%
1620
December1st to 15thDay
1111212448%68%
1620
16th to endDay
212213346%70%
1728
January1st to 15thNight
12213346%71%
2327
16th to endNight
211213346%70%
2349
February1st to 15thNight
12222336%74%
2101
16th to endNight
21121335%8%68%
1895
March1st to 15thNight
11112347%75%
2140
16th to endNight
1112247%77%
2073
April1st to 15thNight
1112235%79%
1799
16th to endNight
1112387%
1798
May1st to 15thNight
112389%
1619
16th to endNight
111489%
1684
June1st to 15thNight
1111290%
1620
16th to endNight
1192%
1620
July1st to 15thNight
1112225%81%
1620
16th to endNight
1111335%5%75%
1701
August1st to 15thNight
1112484%
1800
16th to endNight
11112384%
1910
September1st to 15thNight
111123483%
1890
16th to endNight
11291%
1856
October1st to 15thNight
11125%83%
1815
16th to endNight
11123385%
2118
November1st to 15thNight
11224383%
2275
16th to endNight
11111235%79%
2340
December1st to 15thNight
21221335%7%70%
2340
16th to endNight
322212335%71%
2496

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
14%48%18%27%27%
1612
16th to endDay
16%48%17%27%26%
1872
February1st to 15thDay
13%37%15%30%29%
1751
16th to endDay
13%6%9%19%28%21%
1579
March1st to 15thDay
9%35%17%30%34%
1818
16th to endDay
8%47%19%32%28%
2148
April1st to 15thDay
11%25%14%34%31%
2149
16th to endDay
5%1416%31%41%
2160
May1st to 15thDay
5%2310%31%45%
2331
16th to endDay
42411%28%48%
2432
June1st to 15thDay
4228%18%63%
2340
16th to endDay
5%1139%77%
2340
July1st to 15thDay
12%248%19%51%
2201
16th to endDay
13%5%8%14%23%33%
2309
August1st to 15thDay
7%35%9%21%52%
2146
16th to endDay
10%348%21%50%
2292
September1st to 15thDay
10%35%9%20%50%
2070
16th to endDay
5%135%23%60%
1849
October1st to 15thDay
7%249%28%46%
1815
16th to endDay
6%36%10%22%51%
1752
November1st to 15thDay
9%35%12%29%39%
1584
16th to endDay
9%36%15%27%38%
1620
December1st to 15thDay
13%5%9%22%21%26%
1620
16th to endDay
15%6%9%23%25%19%
1728
January1st to 15thNight
13%5%8%18%25%29%
2327
16th to endNight
16%5%7%18%21%30%
2349
February1st to 15thNight
12%47%16%25%32%
2112
16th to endNight
14%5%9%20%27%22%
1895
March1st to 15thNight
10%38%18%30%29%
2140
16th to endNight
9%310%17%32%26%
2073
April1st to 15thNight
9%47%18%36%24%
1799
16th to endNight
5%25%15%33%37%
1798
May1st to 15thNight
32416%34%39%
1620
16th to endNight
315%14%39%35%
1685
June1st to 15thNight
31212%21%58%
1620
16th to endNight
415%9%78%
1620
July1st to 15thNight
7%238%19%57%
1530
16th to endNight
11%47%15%27%33%
1593
August1st to 15thNight
5%2410%24%51%
1790
16th to endNight
7%238%24%53%
1910
September1st to 15thNight
6%25%10%20%53%
1890
16th to endNight
326%25%61%
1856
October1st to 15thNight
6%15%10%34%40%
1815
16th to endNight
5%25%11%22%52%
2118
November1st to 15thNight
6%35%12%32%39%
2275
16th to endNight
9%25%15%29%36%
2340
December1st to 15thNight
13%5%10%18%23%28%
2340
16th to endNight
16%5%12%19%24%22%
2496

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
12%5%22%44%15%
90
16th to endDay
5%15%29%35%12%2
240
February1st to 15thDay
312%28%33%18%3
266
16th to endDay
5%20%29%30%13%1
238
March1st to 15thDay
417%25%32%15%4
270
16th to endDay
220%32%28%12%4
288
April1st to 15thDay
5%23%31%21%13%4
269
16th to endDay
124%34%25%12%1
270
May1st to 15thDay
116%30%34%10%5%
288
16th to endDay
15%32%33%13%5%
330
June1st to 15thDay
28%28%34%20%5%
315
16th to endDay
2326%30%25%11%
315
July1st to 15thDay
116%40%29%12%
305
16th to endDay
110%36%34%16%
327
August1st to 15thDay
1114%41%28%12%
315
16th to endDay
211%40%30%14%
332
September1st to 15thDay
1123%46%20%6%
315
16th to endDay
15%20%42%22%7%
268
October1st to 15thDay
13%29%39%15%1
255
16th to endDay
26%22%29%33%5%
181
November1st to 15thDay
8%17%26%31%15%
90
16th to endDay
28%27%26%31%3
90
December1st to 15thDay
311%14%33%30%7%
90
16th to endDay
38%29%43%15%
96
January1st to 15thNight
1218%41%24%11%
720
16th to endNight
3323%35%27%6%
768
February1st to 15thNight
1323%37%28%6%
704
16th to endNight
35%28%36%20%5%
632
March1st to 15thNight
15%27%35%24%5%
720
16th to endNight
17%26%32%26%5%
768
April1st to 15thNight
19%32%31%20%4
719
16th to endNight
6%32%32%22%5%
718
May1st to 15thNight
6%25%41%22%3
540
16th to endNight
6%30%34%24%2
563
June1st to 15thNight
326%41%25%2
540
16th to endNight
15%46%35%1
540
July1st to 15thNight
15%41%46%4
510
16th to endNight
1435%51%6%
564
August1st to 15thNight
1433%49%11%
717
16th to endNight
1221%56%16%
764
September1st to 15thNight
5%29%52%12%
720
16th to endNight
110%31%42%13%
671
October1st to 15thNight
1121%33%34%6%
660
16th to endNight
114%30%37%14%
704
November1st to 15thNight
1118%32%36%10%
700
16th to endNight
1117%34%31%12%
720
December1st to 15thNight
3219%37%28%8%
720
16th to endNight
5%5%22%35%24%6%
768
Page generated at 2017-09-20 01:49:58. Version ac04

Copyright 2017 A. Danko


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