Springdale
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Springdale clear sky chart from 2005-11-05 to 2017-09-22.

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
19%
15051
8%
46865
3%
15010
25%
15010
11%
36581

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
11%
747
7%
2604
2%
746
18%
746
6%
2144
January16th to endNight
14%
800
8%
2688
2%
800
21%
800
8%
2176
February1st to 15thNight
15%
732
7%
2437
2%
730
21%
730
9%
1917
February16th to endNight
16%
631
9%
1893
2%
631
22%
631
10%
1477
March1st to 15thNight
19%
720
10%
2160
4%
720
24%
720
10%
1708
March16th to endNight
17%
578
10%
2024
5%
578
24%
578
9%
1582
April1st to 15thNight
16%
539
10%
1766
6%
539
24%
539
10%
1388
April16th to endNight
19%
540
10%
1620
6%
540
23%
540
12%
1265
May1st to 15thNight
25%
540
7%
1464
3%
540
27%
540
15%
1152
May16th to endNight
23%
561
7%
1343
2%
560
25%
560
15%
1092
June1st to 15thNight
24%
540
1%
1260
1%
540
24%
540
12%
1058
June16th to endNight
24%
540
2%
1260
1%
540
26%
540
18%
999
July1st to 15thNight
30%
510
4%
1190
2%
510
31%
510
24%
866
July16th to endNight
28%
565
6%
1410
2%
532
32%
532
17%
1064
August1st to 15thNight
30%
539
8%
1453
3%
535
34%
535
19%
1088
August16th to endNight
33%
573
11%
1744
7%
573
38%
573
19%
1218
September1st to 15thNight
22%
540
10%
1840
5%
540
31%
540
17%
1293
September16th to endNight
20%
514
12%
1890
5%
514
30%
514
15%
1276
October1st to 15thNight
20%
576
14%
1943
5%
576
30%
576
13%
1430
October16th to endNight
17%
736
11%
2288
4%
736
23%
736
11%
1779
November1st to 15thNight
17%
730
10%
2308
3%
730
23%
730
11%
1806
November16th to endNight
12%
750
9%
2700
3%
750
19%
750
7%
2166
December1st to 15thNight
14%
750
6%
2700
2%
750
18%
750
7%
2227
December16th to endNight
15%
800
5%
2880
2%
800
19%
800
6%
2410

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
23%12%47%6%34445%23%
48036
Night
21%11%47%6%35%45%6%24%
47026
TransparencyDay
63%5%10%14%5%
47715
Night
61%5%11%15%5%
46865
SeeingDay
30%13%27%18%7%2
8143
Night
29%14%30%19%6%
15055

By Month

Percentage Cloud Cover NE (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
17%12%5%10%7%46%5%5%6%17%
1332
16th to endDay
15%12%6%8%10%6%8%5%45%16%
1536
February1st to 15thDay
15%12%410%9%46%5%6%5%18%
1420
16th to endDay
15%18%7%12%6%25%44418%
1580
March1st to 15thDay
18%14%6%8%6%3444423%
1790
16th to endDay
21%17%6%9%7%4432320%
2200
April1st to 15thDay
21%16%6%9%6%24445%18%
2183
16th to endDay
25%16%5%5%42323326%
2340
May1st to 15thDay
24%15%47%5%2343424%
2487
16th to endDay
28%13%35%5%33445%21%
2771
June1st to 15thDay
32%11%46%5%25%446%16%
2700
16th to endDay
28%9%35%5%24435%26%
2700
July1st to 15thDay
19%7%35%5%45%5%6%8%29%
2700
16th to endDay
23%8%36%5%45%5%5%6%25%
2661
August1st to 15thDay
24%8%47%6%34446%25%
2496
16th to endDay
22%8%36%6%3445%6%27%
2456
September1st to 15thDay
26%8%36%424345%29%
2119
16th to endDay
20%9%36%6%2445%7%28%
1882
October1st to 15thDay
24%9%26%5%34436%30%
1685
16th to endDay
27%15%38%6%345%45%16%
1584
November1st to 15thDay
24%14%46%433445%23%
1550
16th to endDay
19%14%6%8%6%35%35%421%
1260
December1st to 15thDay
21%12%6%9%7%35%5%5%416%
1260
16th to endDay
25%12%6%8%7%345%4317%
1344
January1st to 15thNight
17%12%6%9%8%45%5%6%7%17%
2604
16th to endNight
15%11%5%8%8%47%5%5%7%19%
2688
February1st to 15thNight
15%11%410%8%46%5%5%6%21%
2437
16th to endNight
15%15%6%7%7%36%5%5%5%22%
1893
March1st to 15thNight
18%10%5%8%6%46%5%5%5%23%
2147
16th to endNight
18%14%5%7%7%3444423%
2024
April1st to 15thNight
22%13%5%7%5%34446%23%
1766
16th to endNight
25%15%45%423235%26%
1620
May1st to 15thNight
26%11%35%5%23445%26%
1464
16th to endNight
30%11%25%433336%24%
1341
June1st to 15thNight
31%10%36%6%3345%6%17%
1260
16th to endNight
28%9%25%424335%28%
1260
July1st to 15thNight
21%6%345%245%6%7%33%
1260
16th to endNight
24%8%25%5%34346%31%
1505
August1st to 15thNight
22%7%36%6%34445%29%
1464
16th to endNight
22%6%25%42436%8%33%
1744
September1st to 15thNight
24%8%24423345%35%
1840
16th to endNight
19%7%345%245%6%7%33%
1890
October1st to 15thNight
22%8%35%6%2445%6%29%
1943
16th to endNight
27%11%25%43435%6%24%
2288
November1st to 15thNight
23%11%45%6%3445%6%23%
2308
16th to endNight
20%13%5%9%5%45%45%6%18%
2700
December1st to 15thNight
19%13%5%9%7%46%45%5%17%
2700
16th to endNight
22%11%6%9%6%45%6%5%5%16%
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
69%5%10%10%3
1333
16th to endDay
69%5%8%11%4
1536
February1st to 15thDay
64%5%12%10%5%
1424
16th to endDay
71%45%11%6%
1580
March1st to 15thDay
65%48%12%7%
1800
16th to endDay
70%45%11%6%1
2200
April1st to 15thDay
68%5%8%11%5%
2183
16th to endDay
64%36%16%8%
2340
May1st to 15thDay
64%49%14%5%
2487
16th to endDay
65%411%13%5%
2775
June1st to 15thDay
69%5%9%12%3
2700
16th to endDay
60%5%8%16%7%
2700
July1st to 15thDay
49%7%15%20%7%
2542
16th to endDay
57%6%12%17%5%
2493
August1st to 15thDay
59%5%13%17%4
2482
16th to endDay
56%6%14%17%5%
2456
September1st to 15thDay
56%5%11%19%6%
2119
16th to endDay
54%5%14%18%7%
1882
October1st to 15thDay
57%412%15%8%1
1685
16th to endDay
71%37%13%4
1584
November1st to 15thDay
65%5%10%13%4
1550
16th to endDay
63%7%10%12%6%
1260
December1st to 15thDay
68%6%11%8%4
1260
16th to endDay
71%38%11%4
1344
January1st to 15thNight
68%6%9%11%4
2604
16th to endNight
65%6%9%13%4
2688
February1st to 15thNight
63%5%12%11%6%
2437
16th to endNight
63%410%14%6%
1893
March1st to 15thNight
62%5%8%14%7%
2160
16th to endNight
65%47%14%7%
2024
April1st to 15thNight
65%37%15%8%
1766
16th to endNight
63%37%15%9%
1620
May1st to 15thNight
61%410%17%5%
1464
16th to endNight
63%411%15%4
1343
June1st to 15thNight
65%6%11%10%4
1260
16th to endNight
58%411%15%8%
1260
July1st to 15thNight
46%6%18%22%5%
1190
16th to endNight
56%5%14%18%4
1410
August1st to 15thNight
53%6%15%18%5%
1453
16th to endNight
49%6%18%19%6%
1744
September1st to 15thNight
52%5%13%22%6%
1840
16th to endNight
50%5%17%18%7%
1890
October1st to 15thNight
55%6%12%15%8%1
1943
16th to endNight
62%410%15%6%
2288
November1st to 15thNight
61%5%11%15%4
2308
16th to endNight
67%5%9%12%4
2700
December1st to 15thNight
68%6%10%10%3
2700
16th to endNight
71%5%9%11%2
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
21%25%35%14%2
240
16th to endDay
24%18%32%20%4
256
February1st to 15thDay
23%18%36%16%42
236
16th to endDay
27%16%31%14%5%3
212
March1st to 15thDay
24%24%27%11%9%2
240
16th to endDay
31%18%26%15%5%1
272
April1st to 15thDay
30%18%28%16%42
300
16th to endDay
34%16%20%20%7%1
450
May1st to 15thDay
37%7%20%21%8%3
468
16th to endDay
37%9%26%18%5%1
519
June1st to 15thDay
41%8%17%20%9%2
495
16th to endDay
31%10%31%14%7%3
495
July1st to 15thDay
21%11%32%23%7%4
475
16th to endDay
29%6%23%28%11%
514
August1st to 15thDay
26%8%29%21%11%3
493
16th to endDay
26%7%25%23%14%3
496
September1st to 15thDay
35%10%30%16%5%
304
16th to endDay
25%16%33%19%3
242
October1st to 15thDay
29%16%24%19%8%2
225
16th to endDay
36%15%30%9%6%1
240
November1st to 15thDay
31%16%28%13%9%
235
16th to endDay
33%17%27%15%4
240
December1st to 15thDay
30%21%30%15%2
240
16th to endDay
32%21%27%13%4
256
January1st to 15thNight
24%22%32%15%4
750
16th to endNight
22%21%34%17%3
800
February1st to 15thNight
23%20%31%20%3
733
16th to endNight
25%15%32%17%6%3
631
March1st to 15thNight
24%21%28%19%5%
720
16th to endNight
30%14%32%17%4
578
April1st to 15thNight
28%16%31%16%5%1
539
16th to endNight
34%11%26%19%6%1
540
May1st to 15thNight
32%7%25%21%12%1
540
16th to endNight
38%8%25%19%7%
561
June1st to 15thNight
37%9%20%22%8%
540
16th to endNight
36%7%26%18%10%1
540
July1st to 15thNight
22%9%33%24%8%1
510
16th to endNight
30%5%27%26%9%
565
August1st to 15thNight
30%427%25%11%
539
16th to endNight
27%5%26%28%9%1
573
September1st to 15thNight
30%7%34%21%5%
540
16th to endNight
27%10%37%21%2
514
October1st to 15thNight
32%10%31%17%7%
576
16th to endNight
36%12%28%18%4
736
November1st to 15thNight
29%16%30%16%6%
730
16th to endNight
28%20%31%16%2
750
December1st to 15thNight
27%20%31%15%4
750
16th to endNight
31%16%29%16%5%1
800
Page generated at 2017-09-23 08:13:41. Version ac04

Copyright 2017 A. Danko


Springdale Clear Sky Chart | Charts Home