Furnace Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Furnace Creek clear sky chart from 2005-11-05 to 2017-08-12.

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
71%
15413
38%
46400
30%
15373
79%
15373
59%
20370

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
70%
719
31%
2506
28%
716
80%
716
50%
1075
January16th to endNight
67%
768
35%
2439
29%
768
77%
768
46%
1191
February1st to 15thNight
67%
700
34%
2108
29%
699
76%
699
49%
1022
February16th to endNight
59%
632
35%
1895
31%
632
70%
632
49%
926
March1st to 15thNight
65%
720
34%
2160
28%
720
77%
720
55%
958
March16th to endNight
61%
768
39%
2034
25%
768
72%
768
57%
986
April1st to 15thNight
57%
719
37%
1799
16%
719
68%
719
57%
903
April16th to endNight
61%
693
39%
1773
18%
693
70%
693
64%
832
May1st to 15thNight
66%
539
37%
1619
24%
539
72%
539
64%
666
May16th to endNight
66%
561
35%
1684
25%
561
73%
561
62%
694
June1st to 15thNight
74%
444
35%
1524
33%
444
80%
444
67%
554
June16th to endNight
84%
360
40%
1440
44%
360
91%
360
76%
433
July1st to 15thNight
85%
340
34%
1360
39%
340
89%
340
61%
474
July16th to endNight
80%
514
37%
1543
34%
481
82%
481
61%
658
August1st to 15thNight
80%
648
39%
1698
25%
645
83%
645
76%
758
August16th to endNight
85%
700
42%
1750
26%
700
87%
700
79%
793
September1st to 15thNight
83%
660
42%
1708
29%
660
88%
660
72%
786
September16th to endNight
82%
656
47%
1815
38%
656
90%
656
83%
717
October1st to 15thNight
75%
660
42%
1815
33%
660
83%
660
66%
815
October16th to endNight
77%
704
44%
2189
40%
704
86%
704
65%
883
November1st to 15thNight
75%
700
39%
2275
36%
700
84%
700
63%
913
November16th to endNight
75%
720
40%
2340
39%
720
82%
720
60%
962
December1st to 15thNight
69%
720
35%
2340
29%
720
78%
720
46%
1102
December16th to endNight
64%
768
33%
2586
28%
768
73%
768
37%
1269

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
111112236%76%
47560
Night
111212235%76%
46589
TransparencyDay
11%35%14%27%37%
47243
Night
12%35%15%26%36%
46406
SeeingDay
412%33%34%12%3
5577
Night
25%17%37%31%4
15421

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
1212225%7%72%
1432
16th to endDay
2213322446%67%
1779
February1st to 15thDay
111111335%9%69%
1751
16th to endDay
2211213448%67%
1579
March1st to 15thDay
1113349%73%
1800
16th to endDay
1221235%9%69%
2185
April1st to 15thDay
1221235%6%73%
2149
16th to endDay
1111123480%
2187
May1st to 15thDay
111237%80%
2331
16th to endDay
11111236%77%
2429
June1st to 15thDay
123483%
2433
16th to endDay
1111388%
2520
July1st to 15thDay
1112112245%74%
2520
16th to endDay
111213346%72%
2515
August1st to 15thDay
11122383%
2164
16th to endDay
1122385%
2100
September1st to 15thDay
11122384%
1922
16th to endDay
1111389%
1815
October1st to 15thDay
1112335%77%
1815
16th to endDay
11112246%77%
1678
November1st to 15thDay
11111123479%
1584
16th to endDay
1111225%6%75%
1620
December1st to 15thDay
212324348%65%
1620
16th to endDay
2323314347%64%
1632
January1st to 15thNight
112223346%71%
2506
16th to endNight
2213314335%67%
2439
February1st to 15thNight
2112313348%67%
2101
16th to endNight
3213212337%67%
1895
March1st to 15thNight
11112348%72%
2160
16th to endNight
1112112347%72%
2034
April1st to 15thNight
21111235%5%75%
1799
16th to endNight
111223479%
1773
May1st to 15thNight
112225%81%
1619
16th to endNight
112123480%
1684
June1st to 15thNight
11122483%
1524
16th to endNight
1111388%
1440
July1st to 15thNight
111112235%77%
1440
16th to endNight
11121334475%
1650
August1st to 15thNight
111112483%
1707
16th to endNight
1123483%
1750
September1st to 15thNight
11233381%
1708
16th to endNight
112388%
1815
October1st to 15thNight
1112345%76%
1815
16th to endNight
11111122481%
2189
November1st to 15thNight
121123479%
2275
16th to endNight
11111347%76%
2340
December1st to 15thNight
2212313347%67%
2340
16th to endNight
2223323347%64%
2586

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%5%8%32%29%9%
1432
16th to endDay
19%410%26%25%13%
1779
February1st to 15thDay
14%5%9%22%30%16%
1751
16th to endDay
17%6%9%20%32%14%
1579
March1st to 15thDay
10%48%22%34%19%
1800
16th to endDay
12%49%21%31%20%
2185
April1st to 15thDay
13%45%17%33%25%
2149
16th to endDay
10%2415%34%32%
2187
May1st to 15thDay
7%3412%30%41%
2331
16th to endDay
10%2412%34%35%
2432
June1st to 15thDay
7%227%21%58%
2433
16th to endDay
411311%77%
2520
July1st to 15thDay
11%236%15%59%
2371
16th to endDay
12%35%8%16%52%
2359
August1st to 15thDay
7%136%15%66%
2149
16th to endDay
6%225%21%62%
2100
September1st to 15thDay
7%235%17%63%
1922
16th to endDay
4117%29%54%
1815
October1st to 15thDay
11%3413%32%35%
1815
16th to endDay
9%35%13%36%32%
1678
November1st to 15thDay
10%26%20%41%18%
1584
16th to endDay
10%46%25%34%18%
1620
December1st to 15thDay
19%5%12%23%31%7%
1620
16th to endDay
21%5%13%26%23%9%
1632
January1st to 15thNight
15%47%27%33%11%
2506
16th to endNight
20%47%22%26%18%
2439
February1st to 15thNight
18%48%20%28%19%
2112
16th to endNight
18%46%22%29%17%
1895
March1st to 15thNight
13%46%20%32%23%
2160
16th to endNight
13%36%20%34%21%
2034
April1st to 15thNight
11%5%6%15%36%25%
1799
16th to endNight
9%3313%32%37%
1773
May1st to 15thNight
8%3314%28%42%
1620
16th to endNight
9%3311%29%42%
1685
June1st to 15thNight
7%329%17%60%
1524
16th to endNight
5%1139%78%
1440
July1st to 15thNight
10%235%15%62%
1360
16th to endNight
13%337%17%54%
1543
August1st to 15thNight
7%225%14%67%
1698
16th to endNight
6%237%17%62%
1750
September1st to 15thNight
9%327%14%62%
1708
16th to endNight
4126%23%62%
1815
October1st to 15thNight
10%3412%29%39%
1815
16th to endNight
10%2310%29%44%
2189
November1st to 15thNight
11%2418%37%25%
2275
16th to endNight
10%46%18%32%27%
2340
December1st to 15thNight
17%5%9%24%27%14%
2340
16th to endNight
21%6%10%25%24%11%
2586

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
5%16%51%26%
60
16th to endDay
6%8%35%28%16%4
185
February1st to 15thDay
5%13%30%30%16%3
266
16th to endDay
12%18%34%22%10%1
238
March1st to 15thDay
6%16%31%27%16%
270
16th to endDay
5%20%32%31%8%
288
April1st to 15thDay
9%28%29%19%10%2
269
16th to endDay
8%25%37%23%21
270
May1st to 15thDay
318%40%25%10%2
288
16th to endDay
220%30%34%10%
330
June1st to 15thDay
311%40%34%8%1
315
16th to endDay
6%32%40%15%4
315
July1st to 15thDay
2330%45%14%3
305
16th to endDay
2228%46%14%5%
327
August1st to 15thDay
3441%35%10%5%
300
16th to endDay
1335%41%11%7%
268
September1st to 15thDay
7%32%43%10%4
255
16th to endDay
28%25%39%20%3
255
October1st to 15thDay
212%36%34%11%1
255
16th to endDay
6%12%24%35%19%2
168
November1st to 15thDay
27%15%33%32%8%
90
16th to endDay
410%36%34%14%
90
December1st to 15thDay
46%26%46%15%
90
16th to endDay
8%11%30%32%12%5%
80
January1st to 15thNight
25%19%37%30%5%
720
16th to endNight
45%18%38%28%4
768
February1st to 15thNight
36%18%40%25%4
704
16th to endNight
5%8%24%36%22%3
632
March1st to 15thNight
27%22%38%22%6%
720
16th to endNight
410%22%35%25%2
768
April1st to 15thNight
5%11%23%36%20%3
719
16th to endNight
210%25%34%23%3
693
May1st to 15thNight
38%21%41%22%2
540
16th to endNight
38%19%35%31%1
563
June1st to 15thNight
15%18%41%31%2
444
16th to endNight
1112%39%41%3
360
July1st to 15thNight
29%43%42%2
340
16th to endNight
114%44%38%1
514
August1st to 15thNight
114%48%33%1
648
16th to endNight
119%37%46%4
700
September1st to 15thNight
1111%36%43%5%
660
16th to endNight
412%32%42%7%
656
October1st to 15thNight
2417%36%33%6%
660
16th to endNight
25%12%32%37%7%
704
November1st to 15thNight
1416%33%36%7%
700
16th to endNight
35%14%35%35%5%
720
December1st to 15thNight
5%7%14%35%32%4
720
16th to endNight
5%10%15%38%25%3
768
Page generated at 2017-08-13 11:16:37. Version ac04

Copyright 2017 A. Danko


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