Parkfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Parkfield clear sky chart from 2005-11-05 to 2018-11-30.

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
76%
17162
33%
51729
30%
17126
79%
17126
50%
25351

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
65%
776
21%
2612
22%
776
67%
776
30%
1513
January16th to endNight
66%
832
27%
2704
30%
832
68%
832
34%
1522
February1st to 15thNight
67%
759
29%
2375
30%
759
71%
759
36%
1332
February16th to endNight
64%
684
28%
2051
29%
684
68%
684
36%
1152
March1st to 15thNight
65%
780
21%
2249
20%
780
68%
780
38%
1300
March16th to endNight
66%
832
25%
2210
20%
832
70%
832
43%
1263
April1st to 15thNight
63%
779
31%
1949
18%
779
67%
779
46%
1100
April16th to endNight
69%
772
32%
1930
15%
772
74%
772
61%
976
May1st to 15thNight
76%
756
32%
1926
19%
756
79%
756
65%
936
May16th to endNight
77%
453
35%
1672
34%
453
82%
453
58%
626
June1st to 15thNight
82%
390
37%
1560
44%
390
87%
390
63%
532
June16th to endNight
92%
390
41%
1560
49%
390
96%
390
84%
442
July1st to 15thNight
95%
376
38%
1486
46%
376
96%
376
77%
455
July16th to endNight
92%
612
39%
1737
34%
579
93%
579
71%
719
August1st to 15thNight
94%
703
42%
1849
29%
700
94%
700
84%
777
August16th to endNight
95%
828
45%
2070
29%
828
95%
828
85%
906
September1st to 15thNight
92%
780
47%
1950
36%
780
93%
780
80%
877
September16th to endNight
91%
776
48%
2089
44%
776
93%
776
80%
885
October1st to 15thNight
78%
780
34%
2327
37%
780
81%
780
54%
1101
October16th to endNight
82%
832
41%
2496
44%
832
85%
832
60%
1129
November1st to 15thNight
79%
820
37%
2608
39%
820
82%
820
52%
1209
November16th to endNight
74%
840
28%
2730
29%
840
77%
840
41%
1408
December1st to 15thNight
68%
780
26%
2677
27%
780
71%
780
31%
1503
December16th to endNight
59%
832
24%
2912
24%
832
64%
832
27%
1688

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
5%312212335%66%
52571
Night
4212223345%66%
51915
TransparencyDay
20%36%19%29%21%
52255
Night
20%37%19%27%21%
51731
SeeingDay
7%6%18%32%26%8%
7561
Night
6%38%32%38%11%
17173

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
9%5%15%5%2445%6%49%
1654
16th to endDay
12%6%24423346%48%
1872
February1st to 15thDay
12%6%23223436%51%
1817
16th to endDay
13%6%34414447%44%
1709
March1st to 15thDay
8%5%245%35%5%6%8%43%
2038
16th to endDay
10%5%24434446%48%
2366
April1st to 15thDay
9%6%33423347%52%
2329
16th to endDay
5%213324346%61%
2305
May1st to 15thDay
2113222247%68%
2350
16th to endDay
3212222336%69%
2790
June1st to 15thDay
1111212235%75%
2730
16th to endDay
111388%
2730
July1st to 15thDay
11122484%
2720
16th to endDay
11111223480%
2676
August1st to 15thDay
111111386%
2352
16th to endDay
111111386%
2484
September1st to 15thDay
111111386%
2340
16th to endDay
1121233379%
2200
October1st to 15thDay
3213323345%67%
1960
16th to endDay
221321335%5%68%
2080
November1st to 15thDay
5%324323346%60%
1909
16th to endDay
5%424424447%54%
1884
December1st to 15thDay
9%426%42445%6%48%
1612
16th to endDay
11%5%34423348%46%
1664
January1st to 15thNight
8%6%25%42445%7%46%
2612
16th to endNight
10%5%24334346%51%
2704
February1st to 15thNight
8%424324447%52%
2365
16th to endNight
9%423423347%54%
2051
March1st to 15thNight
7%425%434448%51%
2249
16th to endNight
6%31332445%7%56%
2210
April1st to 15thNight
4324324346%59%
1949
16th to endNight
311113346%71%
1930
May1st to 15thNight
212212247%72%
1926
16th to endNight
211112235%76%
1671
June1st to 15thNight
11111123479%
1560
16th to endNight
11391%
1560
July1st to 15thNight
11112386%
1566
16th to endNight
111111223380%
1845
August1st to 15thNight
11111288%
1858
16th to endNight
1121387%
2070
September1st to 15thNight
111112286%
1950
16th to endNight
1122385%
2089
October1st to 15thNight
331331223470%
2327
16th to endNight
322212235%71%
2496
November1st to 15thNight
2213223245%67%
2608
16th to endNight
5%3143235%6%9%54%
2730
December1st to 15thNight
7%43443435%7%49%
2677
16th to endNight
11%5%33424447%48%
2912

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
34%49%21%20%10%
1654
16th to endDay
36%310%14%21%12%
1872
February1st to 15thDay
34%27%21%24%8%
1817
16th to endDay
39%38%23%20%4
1709
March1st to 15thDay
35%5%11%20%18%8%
2038
16th to endDay
36%410%23%19%5%
2366
April1st to 15thDay
31%39%25%21%7%
2329
16th to endDay
22%39%27%27%9%
2305
May1st to 15thDay
16%36%26%35%11%
2350
16th to endDay
16%37%31%33%7%
2794
June1st to 15thDay
12%27%19%35%23%
2730
16th to endDay
5%119%38%43%
2730
July1st to 15thDay
6%119%28%52%
2571
16th to endDay
10%2312%29%42%
2521
August1st to 15thDay
6%111%34%45%
2336
16th to endDay
7%111%41%37%
2484
September1st to 15thDay
7%1215%34%39%
2340
16th to endDay
9%2119%40%25%
2200
October1st to 15thDay
18%35%21%26%25%
1960
16th to endDay
17%35%18%30%24%
2080
November1st to 15thDay
24%310%19%30%12%
1909
16th to endDay
29%38%20%27%10%
1884
December1st to 15thDay
35%47%16%21%14%
1612
16th to endDay
36%49%19%20%8%
1664
January1st to 15thNight
35%5%9%19%20%9%
2612
16th to endNight
32%310%16%21%14%
2704
February1st to 15thNight
31%37%22%25%10%
2376
16th to endNight
30%39%26%23%5%
2051
March1st to 15thNight
30%413%23%19%8%
2249
16th to endNight
26%414%24%21%7%
2210
April1st to 15thNight
25%312%28%22%7%
1949
16th to endNight
14%312%29%28%11%
1930
May1st to 15thNight
13%28%26%33%14%
1927
16th to endNight
12%28%32%35%10%
1672
June1st to 15thNight
9%17%17%35%27%
1560
16th to endNight
3110%35%48%
1560
July1st to 15thNight
5%17%28%55%
1486
16th to endNight
10%1210%27%47%
1737
August1st to 15thNight
5%18%31%52%
1849
16th to endNight
5%118%39%43%
2070
September1st to 15thNight
7%1211%28%48%
1950
16th to endNight
6%1119%38%32%
2089
October1st to 15thNight
18%25%19%27%25%
2327
16th to endNight
15%25%19%34%22%
2496
November1st to 15thNight
19%28%22%31%15%
2608
16th to endNight
25%311%20%26%12%
2730
December1st to 15thNight
32%5%8%16%22%14%
2677
16th to endNight
36%411%17%19%9%
2912

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
20%426%30%15%2
192
16th to endDay
15%5%23%29%22%3
304
February1st to 15thDay
17%7%21%26%21%6%
307
16th to endDay
18%14%21%28%15%1
290
March1st to 15thDay
12%11%27%29%17%1
330
16th to endDay
17%12%22%28%16%1
352
April1st to 15thDay
15%16%25%23%13%4
329
16th to endDay
6%15%28%30%15%4
318
May1st to 15thDay
6%10%23%33%19%6%
348
16th to endDay
48%22%36%20%7%
394
June1st to 15thDay
26%18%36%24%12%
375
16th to endDay
1214%33%33%14%
375
July1st to 15thDay
110%37%32%17%
365
16th to endDay
17%32%39%18%
391
August1st to 15thDay
111%38%31%15%
359
16th to endDay
115%32%39%20%
396
September1st to 15thDay
1113%34%36%13%
375
16th to endDay
2212%36%38%7%
375
October1st to 15thDay
3425%40%22%3
375
16th to endDay
6%415%30%35%8%
400
November1st to 15thDay
35%12%31%39%7%
235
16th to endDay
10%8%16%35%23%6%
178
December1st to 15thDay
6%5%25%34%24%2
102
16th to endDay
12%6%15%34%23%7%
96
January1st to 15thNight
13%27%35%31%9%
780
16th to endNight
13%38%36%29%9%
832
February1st to 15thNight
12%49%33%30%10%
764
16th to endNight
14%6%9%40%23%5%
684
March1st to 15thNight
10%312%38%27%7%
780
16th to endNight
8%5%13%34%31%6%
832
April1st to 15thNight
5%8%14%36%29%4
779
16th to endNight
46%18%32%30%9%
772
May1st to 15thNight
2312%38%32%9%
757
16th to endNight
3411%37%37%5%
454
June1st to 15thNight
328%36%43%4
390
16th to endNight
5%34%51%7%
390
July1st to 15thNight
1124%60%12%
376
16th to endNight
1115%57%22%
612
August1st to 15thNight
1222%58%15%
703
16th to endNight
1117%61%19%
828
September1st to 15thNight
1222%54%18%
780
16th to endNight
5%27%47%17%
776
October1st to 15thNight
5%35%36%36%13%
780
16th to endNight
5%15%30%40%16%
832
November1st to 15thNight
418%36%38%10%
820
16th to endNight
6%37%36%34%11%
840
December1st to 15thNight
10%47%38%32%7%
780
16th to endNight
13%6%10%37%25%6%
832
Page generated at 2018-12-01 08:35:39. Version ac04

Copyright 2018 A. Danko


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