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 2017-05-01.

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%
15284
22%
45632
16%
15242
58%
15242
29%
28469

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
56%
497
22%
1494
13%
497
63%
497
31%
918
May16th to endNight
63%
513
18%
1538
13%
513
66%
513
28%
983
June1st to 15thNight
64%
495
16%
1485
13%
495
65%
495
27%
959
June16th to endNight
72%
495
14%
1485
12%
495
73%
495
29%
951
July1st to 15thNight
67%
465
12%
1395
10%
465
67%
465
25%
937
July16th to endNight
72%
522
11%
1469
9%
489
73%
489
25%
1012
August1st to 15thNight
73%
494
16%
1474
14%
491
74%
491
25%
1005
August16th to endNight
61%
586
13%
1725
12%
586
61%
586
20%
1236
September1st to 15thNight
66%
660
18%
1815
16%
660
67%
660
26%
1242
September16th to endNight
55%
657
17%
1815
13%
657
58%
657
24%
1254
October1st to 15thNight
57%
660
31%
1887
27%
660
62%
660
34%
1147
October16th to endNight
58%
704
34%
2112
29%
704
68%
704
39%
1166
November1st to 15thNight
56%
700
31%
2143
27%
700
64%
700
38%
1191
November16th to endNight
44%
720
27%
2340
20%
720
56%
720
32%
1330
December1st to 15thNight
45%
720
24%
2340
18%
720
54%
720
27%
1400
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%
46115
Night
11%42442445%7%45%
45832
TransparencyDay
38%7%11%19%17%5%
45816
Night
36%6%11%18%18%8%
45635
SeeingDay
14%416%22%24%17%
5026
Night
14%5%21%32%22%3
15288

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%8%44%
2138
16th to endDay
9%5%25%5%36%5%8%8%39%
2223
June1st to 15thDay
8%5%245%36%6%6%11%37%
2145
16th to endDay
33146%37%7%8%12%41%
2145
July1st to 15thDay
7%5%26%7%5%7%7%8%9%31%
2145
16th to endDay
5%437%8%48%8%9%11%28%
2283
August1st to 15thDay
8%5%37%7%46%6%8%11%31%
2145
16th to endDay
14%6%26%7%46%7%7%9%26%
2109
September1st to 15thDay
9%5%16%6%46%5%6%8%39%
1815
16th to endDay
16%6%26%5%245%5%7%38%
1815
October1st to 15thDay
14%414323346%52%
1741
16th to endDay
10%31432333459%
1760
November1st to 15thDay
12%5%23323245%55%
1712
16th to endDay
14%424313346%51%
1620
December1st to 15thDay
16%7%2442345%6%44%
1620
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%8%45%
1493
16th to endNight
6%4245%36%6%7%9%42%
1538
June1st to 15thNight
10%5%245%35%5%7%11%37%
1485
16th to endNight
3326%5%45%6%9%13%37%
1485
July1st to 15thNight
8%436%6%35%7%8%10%34%
1485
16th to endNight
5%426%6%47%9%10%11%32%
1577
August1st to 15thNight
7%415%6%47%7%8%13%32%
1485
16th to endNight
11%8%37%6%35%6%6%9%31%
1725
September1st to 15thNight
8%5%25%7%35%7%7%10%36%
1815
16th to endNight
15%6%26%6%35%446%39%
1815
October1st to 15thNight
14%42441333453%
1887
16th to endNight
8%314324335%58%
2112
November1st to 15thNight
10%413422346%56%
2143
16th to endNight
13%413413245%52%
2340
December1st to 15thNight
14%42442345%6%46%
2340
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
35%7%15%21%17%2
2138
16th to endDay
37%9%14%25%11%2
2227
June1st to 15thDay
38%9%17%23%10%
2145
16th to endDay
30%10%19%22%13%2
2145
July1st to 15thDay
41%10%19%17%6%4
2006
16th to endDay
41%14%19%17%6%1
2128
August1st to 15thDay
42%12%15%19%9%1
2132
16th to endDay
50%12%14%13%9%
2109
September1st to 15thDay
39%10%14%15%15%4
1815
16th to endDay
45%7%10%15%14%6%
1815
October1st to 15thDay
34%48%19%23%9%
1741
16th to endDay
30%2418%29%14%
1760
November1st to 15thDay
32%36%18%25%14%
1712
16th to endDay
35%38%19%22%11%
1620
December1st to 15thDay
39%5%9%17%19%7%
1620
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
34%7%14%20%17%4
1494
16th to endNight
35%9%14%22%15%2
1540
June1st to 15thNight
38%7%16%26%10%
1485
16th to endNight
33%12%19%18%12%3
1485
July1st to 15thNight
38%10%21%18%7%3
1395
16th to endNight
36%15%22%18%6%1
1469
August1st to 15thNight
37%13%18%21%8%
1474
16th to endNight
45%11%16%17%8%
1725
September1st to 15thNight
38%12%15%16%12%4
1815
16th to endNight
45%6%11%15%15%5%
1815
October1st to 15thNight
35%38%17%24%10%
1887
16th to endNight
28%36%17%27%15%
2112
November1st to 15thNight
30%36%16%26%17%
2143
16th to endNight
33%48%15%24%14%
2340
December1st to 15thNight
37%410%18%20%8%
2340
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
7%424%28%21%13%
229
16th to endDay
12%110%19%25%29%
267
June1st to 15thDay
14%8%16%29%30%
255
16th to endDay
37%22%26%38%
255
July1st to 15thDay
7%424%31%31%
245
16th to endDay
7%1312%40%34%
270
August1st to 15thDay
15%418%31%30%
253
16th to endDay
16%412%30%35%
268
September1st to 15thDay
14%7%16%34%25%
255
16th to endDay
24%111%25%22%14%
254
October1st to 15thDay
21%117%25%24%9%
255
16th to endDay
11%218%26%31%10%
272
November1st to 15thDay
20%320%25%24%5%
220
16th to endDay
8%7%23%27%26%5%
90
December1st to 15thDay
23%8%27%23%15%1
90
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%423%37%21%2
498
16th to endNight
9%114%31%37%4
515
June1st to 15thNight
12%210%36%32%5%
495
16th to endNight
48%35%40%10%
495
July1st to 15thNight
10%16%33%40%8%
465
16th to endNight
7%5%31%47%7%
522
August1st to 15thNight
10%328%47%8%
494
16th to endNight
15%15%27%39%10%
586
September1st to 15thNight
10%18%27%44%7%
660
16th to endNight
19%211%33%30%2
657
October1st to 15thNight
17%315%33%24%5%
660
16th to endNight
10%321%34%26%3
704
November1st to 15thNight
14%419%38%21%2
700
16th to endNight
15%9%25%29%18%1
720
December1st to 15thNight
16%7%25%33%16%1
720
16th to endNight
22%9%25%32%9%
768
Page generated at 2017-05-02 08:43:41. Version ac04

Copyright 2017 A. Danko


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