Blythe
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blythe clear sky chart from 2005-11-05 to 2017-12-02.

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
51%
16022
22%
47824
16%
15980
58%
15980
29%
29767

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
33%
719
23%
2327
12%
716
47%
716
24%
1413
January16th to endNight
31%
768
23%
2496
14%
768
45%
768
24%
1556
February1st to 15thNight
36%
704
25%
2147
12%
701
50%
701
27%
1315
February16th to endNight
32%
631
25%
1893
10%
631
46%
631
29%
1137
March1st to 15thNight
39%
720
27%
1982
13%
720
50%
720
33%
1199
March16th to endNight
40%
768
21%
2112
11%
768
48%
768
32%
1306
April1st to 15thNight
44%
718
25%
1976
14%
718
52%
718
35%
1184
April16th to endNight
52%
600
27%
1686
17%
600
58%
600
35%
1025
May1st to 15thNight
55%
539
21%
1620
12%
539
62%
539
32%
987
May16th to endNight
62%
561
19%
1682
14%
561
66%
561
28%
1067
June1st to 15thNight
63%
540
15%
1620
12%
540
64%
540
26%
1063
June16th to endNight
70%
540
14%
1620
12%
540
71%
540
27%
1058
July1st to 15thNight
68%
510
12%
1530
10%
510
69%
510
25%
1019
July16th to endNight
72%
564
11%
1595
10%
531
73%
531
24%
1099
August1st to 15thNight
74%
539
15%
1609
13%
536
74%
536
23%
1111
August16th to endNight
62%
640
14%
1883
12%
640
62%
640
21%
1343
September1st to 15thNight
66%
720
17%
1980
16%
720
67%
720
27%
1326
September16th to endNight
58%
717
20%
1980
16%
717
61%
717
26%
1338
October1st to 15thNight
59%
720
30%
2059
27%
720
64%
720
35%
1240
October16th to endNight
57%
768
36%
2304
30%
768
68%
768
40%
1250
November1st to 15thNight
57%
760
30%
2327
26%
760
64%
760
38%
1294
November16th to endNight
46%
780
28%
2535
21%
780
57%
780
33%
1419
December1st to 15thNight
46%
728
24%
2365
18%
728
55%
728
27%
1415
December16th to endNight
37%
768
23%
2496
17%
768
47%
768
23%
1603

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%5%25%5%35%5%6%7%43%
48611
Night
11%42442445%7%45%
48024
TransparencyDay
38%7%12%19%17%5%
48312
Night
36%6%11%18%18%7%
47827
SeeingDay
13%416%23%25%16%
5858
Night
14%5%20%32%23%3
16026

By Month

Percentage Cloud Cover SE (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
13%6%25%314445%46%
1611
16th to endDay
15%5%33323445%46%
1728
February1st to 15thDay
15%5%24323445%46%
1711
16th to endDay
16%5%14423335%48%
1580
March1st to 15thDay
14%41442345%6%48%
1977
16th to endDay
13%5%24424346%47%
2111
April1st to 15thDay
9%4235%3345%6%50%
1972
16th to endDay
8%3144345%5%7%50%
2281
May1st to 15thDay
9%4245%245%7%7%45%
2331
16th to endDay
10%5%25%5%36%5%7%8%39%
2431
June1st to 15thDay
9%5%246%36%6%7%11%36%
2340
16th to endDay
43146%37%7%8%11%39%
2340
July1st to 15thDay
7%5%26%7%5%7%7%7%9%32%
2340
16th to endDay
6%437%8%48%8%9%11%28%
2465
August1st to 15thDay
8%5%37%7%46%7%8%11%30%
2340
16th to endDay
13%6%26%7%46%7%7%9%27%
2301
September1st to 15thDay
9%5%15%6%45%5%6%9%40%
1980
16th to endDay
15%5%26%5%245%5%7%40%
1980
October1st to 15thDay
13%414323346%52%
1899
16th to endDay
10%31432333459%
1920
November1st to 15thDay
12%423323245%55%
1858
16th to endDay
13%424323345%51%
1755
December1st to 15thDay
15%7%2442345%6%44%
1632
16th to endDay
20%7%25%333346%39%
1728
January1st to 15thNight
14%7%24423346%46%
2327
16th to endNight
17%5%3442434446%
2496
February1st to 15thNight
15%424424435%48%
2139
16th to endNight
14%433424346%48%
1893
March1st to 15thNight
10%424434446%51%
1982
16th to endNight
11%4245%2445%6%49%
2112
April1st to 15thNight
11%32332345%6%52%
1976
16th to endNight
8%324435%45%6%51%
1686
May1st to 15thNight
7%4245%35%5%7%7%46%
1619
16th to endNight
6%4245%46%6%7%9%42%
1682
June1st to 15thNight
10%6%245%35%5%7%11%36%
1620
16th to endNight
4326%5%45%6%9%13%36%
1620
July1st to 15thNight
8%436%6%35%7%8%10%34%
1620
16th to endNight
5%325%6%47%9%9%11%32%
1703
August1st to 15thNight
7%415%6%47%7%9%12%31%
1620
16th to endNight
11%7%26%6%35%7%7%10%31%
1883
September1st to 15thNight
8%425%6%35%6%7%10%38%
1980
16th to endNight
13%5%25%6%35%446%41%
1980
October1st to 15thNight
13%424323345%53%
2059
16th to endNight
8%313323335%60%
2304
November1st to 15thNight
11%413412346%56%
2327
16th to endNight
12%413324345%53%
2535
December1st to 15thNight
14%42442345%6%46%
2365
16th to endNight
18%6%34323445%41%
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
39%5%8%15%25%5%
1612
16th to endDay
39%47%17%24%7%
1728
February1st to 15thDay
38%37%20%22%7%
1713
16th to endDay
39%35%20%22%7%
1580
March1st to 15thDay
35%48%20%20%10%
1977
16th to endDay
37%411%21%20%5%
2112
April1st to 15thDay
33%410%20%23%7%
1972
16th to endDay
30%412%21%23%6%
2281
May1st to 15thDay
34%7%14%21%19%3
2331
16th to endDay
38%9%13%24%12%2
2435
June1st to 15thDay
38%9%17%23%10%
2340
16th to endDay
32%11%19%22%12%2
2340
July1st to 15thDay
40%10%19%18%6%3
2201
16th to endDay
41%14%18%17%6%1
2310
August1st to 15thDay
43%11%15%18%8%1
2327
16th to endDay
49%11%15%14%8%
2301
September1st to 15thDay
38%9%14%15%16%4
1980
16th to endDay
43%7%11%16%15%5%
1980
October1st to 15thDay
34%49%19%23%9%
1899
16th to endDay
29%2418%29%15%
1920
November1st to 15thDay
32%37%19%24%13%
1858
16th to endDay
34%38%19%22%11%
1755
December1st to 15thDay
39%5%9%17%19%7%
1632
16th to endDay
47%28%17%16%6%
1728
January1st to 15thNight
38%47%16%24%7%
2327
16th to endNight
42%35%15%22%11%
2496
February1st to 15thNight
38%36%18%19%12%
2148
16th to endNight
36%37%16%24%9%
1893
March1st to 15thNight
34%410%18%23%9%
1982
16th to endNight
35%5%12%19%19%9%
2112
April1st to 15thNight
32%48%21%23%9%
1976
16th to endNight
31%7%8%19%23%10%
1686
May1st to 15thNight
33%7%14%20%18%5%
1620
16th to endNight
35%9%14%22%15%2
1684
June1st to 15thNight
40%7%16%25%10%
1620
16th to endNight
35%12%19%18%11%3
1620
July1st to 15thNight
37%11%21%19%6%2
1530
16th to endNight
36%15%21%17%6%1
1595
August1st to 15thNight
38%14%18%20%8%
1609
16th to endNight
44%11%16%18%8%
1883
September1st to 15thNight
37%11%15%16%14%5%
1980
16th to endNight
42%6%12%17%16%4
1980
October1st to 15thNight
34%49%17%25%9%
2059
16th to endNight
27%36%17%28%16%
2304
November1st to 15thNight
30%37%16%25%15%
2327
16th to endNight
32%48%15%24%14%
2535
December1st to 15thNight
37%411%17%20%7%
2365
16th to endNight
43%48%18%17%7%
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
20%8%36%22%10%2
90
16th to endDay
15%22%37%14%9%
96
February1st to 15thDay
12%17%47%18%3
90
16th to endDay
14%9%39%32%3
81
March1st to 15thDay
14%11%28%32%12%
267
16th to endDay
15%430%30%18%1
288
April1st to 15thDay
13%10%21%26%22%5%
270
16th to endDay
11%221%26%27%11%
270
May1st to 15thDay
8%6%23%27%20%12%
288
16th to endDay
14%211%21%24%25%
331
June1st to 15thDay
15%9%15%31%27%
315
16th to endDay
6%8%24%26%33%
315
July1st to 15thDay
6%421%34%32%
305
16th to endDay
8%315%40%30%
326
August1st to 15thDay
14%6%19%32%26%
313
16th to endDay
15%6%14%28%34%
332
September1st to 15thDay
14%210%18%33%21%
315
16th to endDay
20%11%23%25%18%
314
October1st to 15thDay
20%115%26%23%12%
315
16th to endDay
10%419%26%30%8%
336
November1st to 15thDay
18%320%25%26%5%
276
16th to endDay
7%8%22%30%25%5%
135
December1st to 15thDay
23%8%27%24%14%1
94
16th to endDay
34%14%15%23%8%3
96
January1st to 15thNight
18%11%30%30%8%
720
16th to endNight
19%10%34%30%4
768
February1st to 15thNight
17%10%30%33%6%
704
16th to endNight
15%10%35%33%4
631
March1st to 15thNight
13%9%32%36%7%
720
16th to endNight
14%7%30%31%15%
768
April1st to 15thNight
13%8%30%31%15%
718
16th to endNight
11%6%22%41%18%
600
May1st to 15thNight
10%424%37%20%3
540
16th to endNight
9%115%32%36%4
563
June1st to 15thNight
12%210%37%31%5%
540
16th to endNight
6%7%35%39%10%
540
July1st to 15thNight
9%5%31%41%9%
510
16th to endNight
6%6%31%46%8%
564
August1st to 15thNight
10%329%46%9%
539
16th to endNight
14%16%27%39%10%
640
September1st to 15thNight
10%19%28%42%7%
720
16th to endNight
17%110%31%34%3
717
October1st to 15thNight
15%315%34%25%5%
720
16th to endNight
10%322%32%26%3
768
November1st to 15thNight
14%318%38%21%3
760
16th to endNight
14%8%25%29%20%1
780
December1st to 15thNight
15%7%25%33%16%1
728
16th to endNight
22%9%25%32%9%
768
Page generated at 2017-12-03 11:16:41. Version ac04

Copyright 2017 A. Danko


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