Carvel Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carvel Observatory clear sky chart from 2005-11-05 to 2017-12-20.

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
40%
15559
10%
47727
7%
15534
44%
15534
18%
34055

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
30%
895
7%
2685
4%
895
33%
895
12%
2086
January16th to endNight
31%
882
15%
2802
8%
882
39%
882
16%
1993
February1st to 15thNight
36%
697
9%
2458
7%
697
39%
697
14%
1741
February16th to endNight
45%
632
11%
1998
11%
632
48%
632
18%
1429
March1st to 15thNight
39%
720
14%
2130
10%
720
43%
720
18%
1535
March16th to endNight
37%
768
10%
2067
5%
767
40%
767
17%
1588
April1st to 15thNight
38%
614
11%
1694
6%
614
41%
614
17%
1281
April16th to endNight
37%
537
11%
1617
9%
537
41%
537
18%
1161
May1st to 15thNight
47%
359
7%
1304
6%
359
49%
359
17%
882
May16th to endNight
43%
374
0%
1309
0%
374
43%
374
15%
948
June1st to 15thNight
42%
360
0%
1212
0%
360
42%
360
13%
906
June16th to endNight
50%
360
0%
1080
0%
360
50%
360
18%
770
July1st to 15thNight
60%
340
0%
1097
0%
340
60%
340
22%
731
July16th to endNight
56%
376
2%
1239
1%
354
56%
354
20%
806
August1st to 15thNight
60%
360
5%
1409
7%
358
62%
358
21%
871
August16th to endNight
56%
565
12%
1711
11%
565
58%
565
26%
1088
September1st to 15thNight
57%
648
14%
1779
11%
648
58%
648
32%
1127
September16th to endNight
51%
716
19%
1980
12%
716
56%
716
32%
1244
October1st to 15thNight
40%
720
14%
2156
10%
720
44%
720
21%
1523
October16th to endNight
39%
768
15%
2496
10%
768
47%
768
19%
1708
November1st to 15thNight
32%
934
12%
2703
8%
934
37%
934
15%
2066
November16th to endNight
29%
975
10%
2925
5%
975
34%
975
15%
2214
December1st to 15thNight
34%
975
12%
2925
8%
975
37%
975
15%
2182
December16th to endNight
37%
984
12%
2951
7%
984
42%
984
17%
2175

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%8%47%6%35%5%6%8%32%
49146
Night
10%10%48%6%45%5%5%7%30%
47874
TransparencyDay
48%7%18%19%5%
48793
Night
50%6%15%18%6%
47732
SeeingDay
15%5%22%31%19%6%
6663
Night
15%5%25%34%17%2
15573

By Month

Percentage Cloud Cover NW (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
6%13%6%9%10%45%5%5%6%26%
1253
16th to endDay
7%14%6%7%5%45%5%5%6%29%
1433
February1st to 15thDay
10%10%5%9%6%46%6%5%7%25%
1406
16th to endDay
6%13%8%8%9%46%5%6%6%24%
1473
March1st to 15thDay
7%13%6%9%9%45%5%6%7%25%
1830
16th to endDay
12%12%5%8%6%36%6%7%7%25%
2152
April1st to 15thDay
12%11%47%6%35%47%8%28%
2253
16th to endDay
14%10%36%6%45%5%6%7%28%
2343
May1st to 15thDay
10%7%36%6%45%5%5%8%35%
2646
16th to endDay
19%6%36%5%35%5%5%7%31%
2802
June1st to 15thDay
18%7%46%7%37%5%5%7%26%
2745
16th to endDay
14%5%25%6%36%5%6%9%33%
2880
July1st to 15thDay
12%416%5%35%6%6%9%38%
2793
16th to endDay
11%3245%36%6%7%8%40%
2846
August1st to 15thDay
12%4145%35%6%7%10%37%
2541
16th to endDay
9%5%25%5%35%6%7%9%39%
2492
September1st to 15thDay
14%7%35%43435%7%40%
2178
16th to endDay
11%5%25%5%3445%9%42%
1980
October1st to 15thDay
14%10%48%5%34445%35%
1801
16th to endDay
11%10%46%5%45%7%6%7%31%
1728
November1st to 15thDay
11%15%5%9%6%35%5%5%6%25%
1469
16th to endDay
7%11%6%10%7%45%448%30%
1365
December1st to 15thDay
7%13%7%11%8%47%445%23%
1365
16th to endDay
6%12%6%9%9%5%6%45%7%26%
1372
January1st to 15thNight
7%13%7%9%8%5%6%5%5%6%24%
2685
16th to endNight
7%12%5%8%7%45%5%47%30%
2802
February1st to 15thNight
7%10%5%11%9%45%5%47%28%
2447
16th to endNight
7%12%6%7%6%46%5%5%8%28%
1998
March1st to 15thNight
8%9%5%9%7%5%5%5%5%7%29%
2130
16th to endNight
9%13%5%9%7%35%6%6%7%24%
2067
April1st to 15thNight
11%10%38%8%47%5%6%6%26%
1694
16th to endNight
13%11%37%6%25%5%5%7%30%
1617
May1st to 15thNight
9%9%27%6%47%6%7%7%31%
1304
16th to endNight
19%8%46%5%35%5%5%7%27%
1309
June1st to 15thNight
18%7%47%6%45%6%6%7%25%
1212
16th to endNight
12%5%37%7%46%7%8%10%27%
1080
July1st to 15thNight
12%4345%35%5%6%10%37%
1164
16th to endNight
11%325%5%46%6%8%11%35%
1323
August1st to 15thNight
10%415%6%26%6%6%9%39%
1416
16th to endNight
10%6%25%5%345%7%10%37%
1711
September1st to 15thNight
12%5%25%5%245%5%7%45%
1779
16th to endNight
11%5%244245%5%8%46%
1980
October1st to 15thNight
13%9%47%6%3445%6%33%
2156
16th to endNight
9%9%38%5%35%6%6%7%34%
2496
November1st to 15thNight
13%12%6%10%6%4445%6%25%
2703
16th to endNight
8%12%6%9%8%46%45%5%27%
2925
December1st to 15thNight
9%14%5%8%6%445%5%8%26%
2925
16th to endNight
5%14%6%9%8%46%5%5%7%26%
2951

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
56%6%15%14%5%
1253
16th to endDay
54%7%13%15%7%1
1433
February1st to 15thDay
56%6%15%15%5%
1406
16th to endDay
57%7%14%15%5%
1473
March1st to 15thDay
55%7%15%16%4
1830
16th to endDay
54%8%14%17%4
2153
April1st to 15thDay
51%8%15%18%5%
2253
16th to endDay
52%6%16%17%6%1
2343
May1st to 15thDay
46%5%15%22%9%
2646
16th to endDay
49%7%14%19%7%
2807
June1st to 15thDay
53%7%18%16%3
2745
16th to endDay
45%8%21%19%4
2880
July1st to 15thDay
40%9%22%23%3
2631
16th to endDay
38%9%29%20%2
2667
August1st to 15thDay
39%10%30%17%2
2523
16th to endDay
37%8%27%21%5%
2492
September1st to 15thDay
43%6%20%22%6%1
2178
16th to endDay
38%6%17%28%7%1
1980
October1st to 15thDay
49%6%15%21%6%
1801
16th to endDay
48%8%15%23%3
1728
November1st to 15thDay
57%5%15%16%4
1469
16th to endDay
53%6%16%16%6%1
1365
December1st to 15thDay
61%6%10%15%4
1365
16th to endDay
55%6%13%15%7%
1372
January1st to 15thNight
60%6%14%13%31
2685
16th to endNight
52%5%13%17%8%2
2802
February1st to 15thNight
54%5%15%16%6%
2459
16th to endNight
51%6%14%17%8%1
1998
March1st to 15thNight
51%6%14%20%7%
2130
16th to endNight
56%6%14%16%5%
2070
April1st to 15thNight
55%6%13%17%6%1
1694
16th to endNight
51%6%12%19%9%
1617
May1st to 15thNight
48%6%12%18%12%
1305
16th to endNight
53%7%13%16%7%2
1309
June1st to 15thNight
55%8%15%15%4
1212
16th to endNight
47%9%21%18%2
1080
July1st to 15thNight
41%10%23%20%5%
1097
16th to endNight
40%11%26%18%3
1239
August1st to 15thNight
37%11%28%20%2
1409
16th to endNight
38%8%21%24%6%
1711
September1st to 15thNight
37%5%19%26%10%1
1779
16th to endNight
34%6%17%27%11%1
1980
October1st to 15thNight
49%6%13%23%7%
2156
16th to endNight
46%8%17%22%5%
2496
November1st to 15thNight
58%5%10%19%5%
2703
16th to endNight
56%6%14%14%5%1
2925
December1st to 15thNight
55%6%14%17%5%
2925
16th to endNight
55%415%17%6%
2951

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
6%5%28%28%26%5%
60
16th to endDay
4315%42%23%10%
64
February1st to 15thDay
18%431%34%9%1
61
16th to endDay
15%6%24%27%21%6%
132
March1st to 15thDay
14%6%31%31%14%
270
16th to endDay
16%428%34%14%1
288
April1st to 15thDay
16%11%31%31%8%1
269
16th to endDay
21%8%23%27%14%4
270
May1st to 15thDay
10%8%22%33%19%5%
423
16th to endDay
19%418%32%18%5%
517
June1st to 15thDay
20%6%21%29%17%5%
540
16th to endDay
15%419%31%22%6%
675
July1st to 15thDay
11%218%34%26%7%
565
16th to endDay
12%419%30%26%7%
515
August1st to 15thDay
12%13%30%25%18%
336
16th to endDay
12%322%32%23%4
332
September1st to 15thDay
22%420%28%18%6%
315
16th to endDay
12%10%23%26%19%7%
315
October1st to 15thDay
24%5%21%26%14%8%
199
16th to endDay
20%6%26%26%17%2
144
November1st to 15thDay
21%28%33%11%4
121
16th to endDay
11%10%31%31%6%10%
90
December1st to 15thDay
14%8%24%30%18%3
90
16th to endDay
9%227%29%22%8%
72
January1st to 15thNight
15%7%29%33%12%2
900
16th to endNight
13%9%30%30%13%1
882
February1st to 15thNight
10%8%24%35%18%2
704
16th to endNight
12%5%23%34%20%3
632
March1st to 15thNight
11%331%35%15%2
720
16th to endNight
16%424%36%15%2
768
April1st to 15thNight
15%7%25%34%15%1
614
16th to endNight
19%6%24%34%15%
537
May1st to 15thNight
13%5%22%39%17%1
360
16th to endNight
21%320%36%16%2
375
June1st to 15thNight
21%5%20%33%15%3
360
16th to endNight
14%319%33%26%1
360
July1st to 15thNight
14%313%43%23%1
340
16th to endNight
13%218%38%25%1
376
August1st to 15thNight
12%213%31%34%5%
360
16th to endNight
12%218%39%25%1
565
September1st to 15thNight
16%214%39%24%2
648
16th to endNight
13%424%36%18%2
716
October1st to 15thNight
19%324%32%18%1
720
16th to endNight
14%5%29%35%13%1
768
November1st to 15thNight
18%6%28%31%12%1
934
16th to endNight
14%6%34%31%11%2
975
December1st to 15thNight
16%6%27%30%15%1
975
16th to endNight
11%5%27%33%18%3
984
Page generated at 2017-12-21 05:04:48. Version ac04

Copyright 2017 A. Danko


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