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 2017-08-12.

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
40%
15018
10%
46116
7%
14993
44%
14993
18%
32987

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%
352
5%
1377
7%
350
62%
350
20%
859
August16th to endNight
55%
518
11%
1568
10%
518
57%
518
26%
1001
September1st to 15thNight
57%
594
15%
1631
11%
594
58%
594
32%
1038
September16th to endNight
51%
656
18%
1815
11%
656
56%
656
33%
1135
October1st to 15thNight
41%
660
15%
1976
11%
660
45%
660
21%
1397
October16th to endNight
41%
704
14%
2288
10%
704
47%
704
19%
1582
November1st to 15thNight
33%
860
13%
2489
9%
860
38%
860
16%
1878
November16th to endNight
29%
900
11%
2700
5%
900
34%
900
15%
2043
December1st to 15thNight
32%
900
11%
2700
7%
900
35%
900
14%
2072
December16th to endNight
38%
960
12%
2880
7%
960
42%
960
17%
2125

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
12%8%47%6%35%5%6%8%32%
47890
Night
10%10%48%6%45%5%5%7%30%
46263
TransparencyDay
48%7%18%19%5%
47537
Night
51%6%15%18%6%
46121
SeeingDay
15%5%22%31%19%6%
6258
Night
15%5%25%34%17%2
15032

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%5%145%35%6%7%11%36%
2488
16th to endDay
9%5%26%5%35%6%7%9%38%
2283
September1st to 15thDay
14%7%35%43435%7%39%
1996
16th to endDay
10%5%25%5%4445%9%42%
1815
October1st to 15thDay
14%9%37%5%34446%35%
1651
16th to endDay
10%10%46%5%45%7%6%7%31%
1584
November1st to 15thDay
11%14%5%7%6%35%5%5%7%27%
1354
16th to endDay
7%11%6%10%7%45%337%31%
1260
December1st to 15thDay
8%13%8%12%8%5%8%445%19%
1260
16th to endDay
6%13%6%9%9%5%6%45%7%25%
1344
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%10%38%
1384
16th to endNight
11%6%25%5%345%7%11%36%
1568
September1st to 15thNight
11%5%25%5%235%5%7%44%
1631
16th to endNight
10%5%244245%6%8%46%
1815
October1st to 15thNight
12%9%47%6%345%5%7%33%
1976
16th to endNight
10%10%38%5%35%6%6%7%33%
2288
November1st to 15thNight
14%11%5%9%6%4445%6%26%
2489
16th to endNight
8%12%6%9%7%46%45%5%28%
2700
December1st to 15thNight
10%15%5%9%7%445%5%8%24%
2700
16th to endNight
5%14%6%9%8%46%447%26%
2880

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
40%10%30%17%1
2470
16th to endDay
38%8%26%20%5%
2283
September1st to 15thDay
43%6%21%22%6%
1996
16th to endDay
37%6%17%29%6%1
1815
October1st to 15thDay
48%6%15%22%6%
1651
16th to endDay
47%7%15%25%3
1584
November1st to 15thDay
54%5%16%16%5%
1354
16th to endDay
53%6%15%16%6%1
1260
December1st to 15thDay
64%6%10%14%3
1260
16th to endDay
56%6%14%16%6%
1344
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
38%11%28%19%1
1377
16th to endNight
39%7%22%23%6%
1568
September1st to 15thNight
37%5%19%26%10%
1631
16th to endNight
34%7%17%28%10%2
1815
October1st to 15thNight
49%5%13%23%7%
1976
16th to endNight
47%8%17%22%4
2288
November1st to 15thNight
56%5%11%20%5%
2489
16th to endNight
57%6%14%15%5%1
2700
December1st to 15thNight
58%6%13%16%4
2700
16th to endNight
55%415%17%6%
2880

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%12%30%24%19%
321
16th to endDay
15%422%32%20%4
268
September1st to 15thDay
23%320%29%18%5%
255
16th to endDay
9%12%25%29%16%6%
255
October1st to 15thDay
23%6%21%29%12%6%
149
16th to endDay
19%418%32%20%4
96
November1st to 15thDay
25%33%28%11%1
81
16th to endDay
15%8%26%26%8%15%
60
December1st to 15thDay
20%130%23%20%5%
60
16th to endDay
10%320%31%25%9%
64
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%30%35%5%
352
16th to endNight
13%217%38%25%1
518
September1st to 15thNight
16%214%40%23%2
594
16th to endNight
12%426%36%17%2
656
October1st to 15thNight
18%424%33%17%1
660
16th to endNight
15%427%36%14%1
704
November1st to 15thNight
18%6%29%30%12%1
860
16th to endNight
14%6%33%32%11%2
900
December1st to 15thNight
18%7%27%30%15%2
900
16th to endNight
11%5%26%34%18%3
960
Page generated at 2017-08-13 12:16:37. Version ac04

Copyright 2017 A. Danko


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