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Prescott
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prescott clear sky chart from 2005-11-05 to 2018-03-11.

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
71%
16380
35%
49079
29%
16341
78%
16341
52%
23560

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
65%
779
32%
2522
29%
776
73%
776
45%
1233
January16th to endNight
62%
832
36%
2704
34%
832
71%
832
42%
1368
February1st to 15thNight
66%
758
35%
2357
29%
758
76%
758
50%
1116
February16th to endNight
59%
684
35%
2051
32%
684
67%
684
44%
1071
March1st to 15thNight
63%
764
36%
2123
27%
764
72%
764
52%
1070
March16th to endNight
65%
768
35%
2112
25%
768
73%
768
55%
1042
April1st to 15thNight
57%
719
29%
1978
16%
719
67%
719
51%
1021
April16th to endNight
59%
543
44%
1642
27%
543
74%
543
67%
665
May1st to 15thNight
70%
539
36%
1619
28%
539
76%
539
58%
719
May16th to endNight
72%
561
38%
1684
28%
561
78%
561
66%
699
June1st to 15thNight
77%
540
33%
1620
29%
540
78%
540
67%
681
June16th to endNight
84%
540
34%
1620
31%
540
86%
540
72%
659
July1st to 15thNight
85%
510
24%
1530
21%
510
85%
510
47%
782
July16th to endNight
81%
564
22%
1593
18%
531
83%
531
38%
909
August1st to 15thNight
88%
539
30%
1611
26%
536
89%
536
50%
799
August16th to endNight
84%
664
33%
1855
28%
664
84%
664
45%
1014
September1st to 15thNight
82%
720
30%
1980
26%
720
83%
720
50%
1056
September16th to endNight
81%
716
46%
1980
35%
716
86%
716
72%
863
October1st to 15thNight
75%
720
38%
2046
30%
720
80%
720
62%
934
October16th to endNight
80%
768
44%
2304
39%
768
85%
768
63%
1012
November1st to 15thNight
74%
760
37%
2374
32%
760
80%
760
55%
1081
November16th to endNight
70%
780
41%
2535
38%
780
79%
780
56%
1112
December1st to 15thNight
70%
780
35%
2535
32%
780
76%
780
46%
1227
December16th to endNight
62%
832
35%
2704
32%
832
69%
832
38%
1427

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
3313323446%62%
49546
Night
2213323345%66%
49275
TransparencyDay
21%35%15%28%25%
49241
Night
18%36%15%28%26%
49081
SeeingDay
410%22%31%22%8%
6065
Night
3314%34%35%8%
16390

By Month

Percentage Cloud Cover SW (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
3424423345%61%
1746
16th to endDay
5%5%13324346%58%
1872
February1st to 15thDay
36%23324336%59%
1833
16th to endDay
46%25%42345%7%54%
1709
March1st to 15thDay
3423323445%62%
2072
16th to endDay
331332344464%
2112
April1st to 15thDay
2313423346%63%
1970
16th to endDay
1212212336%70%
2315
May1st to 15thDay
3213223335%68%
2331
16th to endDay
321221333471%
2429
June1st to 15thDay
1111212235%77%
2340
16th to endDay
11111222380%
2340
July1st to 15thDay
3214436%6%6%7%53%
2340
16th to endDay
6%436%7%5%6%7%8%8%35%
2467
August1st to 15thDay
5%4245%36%5%6%8%46%
2340
16th to endDay
5%324425%5%6%7%51%
2343
September1st to 15thDay
5%3145%35%5%5%6%53%
1980
16th to endDay
211222223472%
1980
October1st to 15thDay
221222333473%
1914
16th to endDay
212212335%72%
1920
November1st to 15thDay
123324346%68%
1811
16th to endDay
4312212246%68%
1755
December1st to 15thDay
46%23423437%58%
1755
16th to endDay
5%6%35%42345%6%53%
1872
January1st to 15thNight
3324423445%61%
2522
16th to endNight
5%423423345%61%
2704
February1st to 15thNight
3313312345%65%
2346
16th to endNight
3324425%45%7%58%
2051
March1st to 15thNight
341231336%6%63%
2123
16th to endNight
2222223346%66%
2112
April1st to 15thNight
322332334465%
1978
16th to endNight
11221224477%
1642
May1st to 15thNight
222213235%73%
1619
16th to endNight
21121123478%
1684
June1st to 15thNight
111121213478%
1620
16th to endNight
1221212281%
1620
July1st to 15thNight
21134345%6%7%58%
1620
16th to endNight
32145%47%6%8%12%42%
1701
August1st to 15thNight
2123335%6%10%58%
1620
16th to endNight
22134345%7%8%56%
1855
September1st to 15thNight
22134245%6%6%59%
1980
16th to endNight
21111113480%
1980
October1st to 15thNight
2212212345%73%
2046
16th to endNight
1212212225%75%
2304
November1st to 15thNight
2212323345%68%
2374
16th to endNight
3212212235%70%
2535
December1st to 15thNight
331232445%5%62%
2535
16th to endNight
5%424424445%56%
2704

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
24%26%16%33%17%
1747
16th to endDay
25%35%18%29%16%
1872
February1st to 15thDay
26%16%18%26%21%
1833
16th to endDay
27%3417%28%17%
1709
March1st to 15thDay
22%2215%35%20%
2072
16th to endDay
21%3417%35%17%
2112
April1st to 15thDay
20%2418%33%20%
1970
16th to endDay
15%2315%34%28%
2315
May1st to 15thDay
17%2416%31%27%
2331
16th to endDay
16%2411%34%30%
2432
June1st to 15thDay
11%127%26%51%
2340
16th to endDay
10%126%19%60%
2340
July1st to 15thDay
26%7%8%14%16%26%
2201
16th to endDay
38%10%15%14%15%5%
2312
August1st to 15thDay
30%6%9%16%18%18%
2325
16th to endDay
29%6%9%16%24%13%
2343
September1st to 15thDay
27%5%10%15%22%18%
1980
16th to endDay
14%2311%33%34%
1980
October1st to 15thDay
15%2314%28%35%
1914
16th to endDay
14%2411%34%32%
1920
November1st to 15thDay
17%2419%31%24%
1811
16th to endDay
18%1318%29%28%
1755
December1st to 15thDay
25%27%21%25%17%
1755
16th to endDay
29%27%20%27%11%
1872
January1st to 15thNight
23%26%16%32%17%
2522
16th to endNight
26%2417%30%19%
2704
February1st to 15thNight
20%27%18%29%22%
2357
16th to endNight
24%35%18%29%18%
2051
March1st to 15thNight
19%2414%35%23%
2123
16th to endNight
17%27%18%33%19%
2112
April1st to 15thNight
20%25%14%35%21%
1978
16th to endNight
9%15%13%35%33%
1642
May1st to 15thNight
14%2415%30%32%
1620
16th to endNight
11%1211%39%33%
1685
June1st to 15thNight
12%116%23%55%
1620
16th to endNight
10%11415%65%
1620
July1st to 15thNight
20%6%11%14%18%28%
1530
16th to endNight
26%9%17%21%18%7%
1593
August1st to 15thNight
18%6%12%19%21%21%
1611
16th to endNight
22%6%9%20%24%15%
1855
September1st to 15thNight
21%5%11%18%21%22%
1980
16th to endNight
9%1210%36%38%
1980
October1st to 15thNight
14%2415%26%36%
2046
16th to endNight
13%25%11%27%40%
2304
November1st to 15thNight
17%2416%35%23%
2374
16th to endNight
17%1316%30%31%
2535
December1st to 15thNight
22%36%19%26%21%
2535
16th to endNight
28%36%20%27%12%
2704

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
11%5%22%33%21%6%
135
16th to endDay
311%20%26%27%11%
144
February1st to 15thDay
5%14%26%28%16%9%
258
16th to endDay
11%22%30%22%11%2
290
March1st to 15thDay
7%16%26%29%15%5%
312
16th to endDay
5%23%29%24%14%3
288
April1st to 15thDay
7%19%30%25%8%7%
269
16th to endDay
425%36%21%8%4
270
May1st to 15thDay
5%17%32%27%11%5%
288
16th to endDay
411%30%32%17%4
330
June1st to 15thDay
29%34%31%14%6%
315
16th to endDay
119%44%20%13%
315
July1st to 15thDay
2115%42%29%8%
305
16th to endDay
416%34%33%18%
327
August1st to 15thDay
6%8%33%36%13%
315
16th to endDay
5%17%34%34%15%
332
September1st to 15thDay
4216%40%27%7%
315
16th to endDay
48%21%36%22%6%
315
October1st to 15thDay
38%29%32%21%5%
249
16th to endDay
1218%29%32%15%
144
November1st to 15thDay
16%20%30%32%8%
135
16th to endDay
5%9%28%24%23%8%
135
December1st to 15thDay
27%17%37%30%5%
135
16th to endDay
49%15%33%30%7%
144
January1st to 15thNight
4415%39%25%10%
780
16th to endNight
7%418%38%27%5%
832
February1st to 15thNight
4417%40%27%5%
764
16th to endNight
5%5%23%41%19%3
684
March1st to 15thNight
5%6%19%36%28%3
764
16th to endNight
45%19%37%28%4
768
April1st to 15thNight
46%24%35%25%3
719
16th to endNight
8%28%34%23%5%
543
May1st to 15thNight
25%16%41%29%4
540
16th to endNight
2316%39%32%4
563
June1st to 15thNight
1114%43%32%5%
540
16th to endNight
18%34%47%7%
540
July1st to 15thNight
2224%59%10%
510
16th to endNight
1216%60%18%
564
August1st to 15thNight
3116%60%18%
539
16th to endNight
2215%55%23%
664
September1st to 15thNight
21424%52%15%
720
16th to endNight
2112%30%42%10%
716
October1st to 15thNight
2315%36%35%6%
720
16th to endNight
1210%33%38%14%
768
November1st to 15thNight
3115%38%33%8%
760
16th to endNight
4316%33%32%9%
780
December1st to 15thNight
6%215%40%30%4
780
16th to endNight
7%6%14%39%25%6%
832
Page generated at 2018-03-12 10:28:12. Version ac04

Copyright 2018 A. Danko


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