McKinney
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the McKinney clear sky chart from 2005-11-05 to 2018-02-14.

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%
16264
30%
48779
21%
16220
60%
16220
40%
26657

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
40%
972
31%
2522
13%
970
51%
970
40%
1476
January16th to endNight
39%
1040
34%
2704
13%
1040
51%
1040
43%
1548
February1st to 15thNight
34%
841
27%
2361
10%
837
45%
837
35%
1381
February16th to endNight
27%
609
31%
1871
11%
609
43%
609
34%
1036
March1st to 15thNight
33%
540
28%
1980
16%
540
48%
540
27%
1101
March16th to endNight
39%
576
24%
2112
18%
576
51%
576
29%
1160
April1st to 15thNight
35%
539
25%
1962
14%
539
52%
539
31%
1030
April16th to endNight
39%
540
26%
1719
19%
540
53%
540
35%
949
May1st to 15thNight
39%
540
24%
1620
14%
540
53%
540
34%
947
May16th to endNight
55%
563
27%
1684
23%
561
64%
561
40%
930
June1st to 15thNight
71%
540
24%
1620
25%
540
76%
540
52%
803
June16th to endNight
76%
540
26%
1620
29%
540
79%
540
49%
830
July1st to 15thNight
82%
510
23%
1530
27%
510
83%
510
46%
799
July16th to endNight
89%
564
32%
1594
39%
531
90%
531
58%
742
August1st to 15thNight
90%
539
37%
1610
44%
536
90%
536
61%
728
August16th to endNight
79%
573
30%
1869
35%
573
80%
573
39%
1006
September1st to 15thNight
71%
540
24%
1980
28%
540
73%
540
35%
1023
September16th to endNight
74%
537
35%
1980
38%
537
78%
537
41%
957
October1st to 15thNight
64%
630
33%
2070
28%
630
68%
630
43%
1051
October16th to endNight
52%
768
38%
2304
22%
768
63%
768
49%
1148
November1st to 15thNight
52%
773
31%
2293
19%
773
60%
773
41%
1242
November16th to endNight
44%
975
35%
2535
17%
975
54%
975
41%
1472
December1st to 15thNight
39%
975
30%
2535
14%
975
49%
975
35%
1576
December16th to endNight
34%
1040
27%
2704
11%
1040
44%
1040
34%
1722

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
10%424424446%51%
49295
Night
9%313323347%56%
48975
TransparencyDay
32%410%24%22%6%
48995
Night
28%39%23%24%10%
48780
SeeingDay
10%318%27%28%10%
6055
Night
11%5%26%34%19%2
16267

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%13212235%56%
1746
16th to endDay
13%312323335%56%
1872
February1st to 15thDay
15%5%2442233451%
1811
16th to endDay
16%5%23311335%53%
1601
March1st to 15thDay
18%5%24323246%45%
1980
16th to endDay
15%5%35%42333448%
2110
April1st to 15thDay
12%5%13324347%50%
1986
16th to endDay
13%414323446%48%
2238
May1st to 15thDay
14%5%35%5%3435%6%43%
2331
16th to endDay
10%5%25%5%36%5%6%7%40%
2430
June1st to 15thDay
5%3145%25%5%5%9%51%
2340
16th to endDay
5%323425%46%8%52%
2340
July1st to 15thDay
6%323436%6%7%8%45%
2340
16th to endDay
42135%35%5%7%10%51%
2466
August1st to 15thDay
3212325%5%6%8%58%
2340
16th to endDay
6%315%6%47%6%7%9%42%
2330
September1st to 15thDay
11%41442345%8%49%
1980
16th to endDay
7%4233145%5%7%54%
1980
October1st to 15thDay
10%313322335%58%
1878
16th to endDay
8%31221223466%
1920
November1st to 15thDay
9%424325%34456%
1894
16th to endDay
12%413212225%60%
1755
December1st to 15thDay
16%6%14312335%50%
1755
16th to endDay
18%5%24313345%47%
1872
January1st to 15thNight
11%313422345%57%
2522
16th to endNight
11%413222345%60%
2704
February1st to 15thNight
12%42431333455%
2351
16th to endNight
14%41322233457%
1871
March1st to 15thNight
15%42431345%5%49%
1980
16th to endNight
12%424323445%53%
2112
April1st to 15thNight
9%42332345%6%54%
1962
16th to endNight
11%423323445%54%
1719
May1st to 15thNight
9%5%24424447%51%
1619
16th to endNight
6%41332346%11%51%
1683
June1st to 15thNight
3213313449%62%
1620
16th to endNight
321332345%10%59%
1620
July1st to 15thNight
42133235%7%12%52%
1620
16th to endNight
21221345%10%63%
1702
August1st to 15thNight
21121335%8%67%
1620
16th to endNight
4413325%5%6%12%50%
1869
September1st to 15thNight
10%42332235%7%53%
1980
16th to endNight
6%314323347%59%
1980
October1st to 15thNight
9%312313346%60%
2070
16th to endNight
8%21221132368%
2304
November1st to 15thNight
7%314322335%61%
2293
16th to endNight
11%31421334459%
2535
December1st to 15thNight
13%5%23313236%52%
2535
16th to endNight
15%7%24312336%48%
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
31%28%21%29%6%
1747
16th to endDay
30%26%21%28%9%
1872
February1st to 15thDay
37%25%24%22%6%
1812
16th to endDay
35%26%23%21%11%
1601
March1st to 15thDay
41%36%19%20%9%
1980
16th to endDay
39%310%18%21%6%
2112
April1st to 15thDay
34%310%22%18%10%
1986
16th to endDay
35%49%20%23%6%
2238
May1st to 15thDay
41%38%18%19%7%
2331
16th to endDay
39%5%11%23%17%2
2434
June1st to 15thDay
28%5%13%28%20%2
2340
16th to endDay
27%5%12%28%21%4
2340
July1st to 15thDay
28%6%14%33%15%1
2201
16th to endDay
23%6%19%32%16%1
2311
August1st to 15thDay
19%6%14%32%24%3
2326
16th to endDay
33%6%14%29%13%2
2330
September1st to 15thDay
31%410%25%18%7%
1980
16th to endDay
27%48%24%26%8%
1980
October1st to 15thDay
28%310%22%20%14%
1878
16th to endDay
22%26%19%30%17%
1920
November1st to 15thDay
31%28%24%24%8%
1894
16th to endDay
29%2419%32%11%
1755
December1st to 15thDay
38%26%19%26%6%
1755
16th to endDay
39%26%23%21%6%
1872
January1st to 15thNight
29%26%19%30%10%
2522
16th to endNight
28%25%20%30%13%
2704
February1st to 15thNight
33%27%21%23%12%
2361
16th to endNight
31%27%22%21%13%
1871
March1st to 15thNight
36%28%18%22%11%
1980
16th to endNight
33%410%21%24%5%
2112
April1st to 15thNight
29%410%22%18%14%
1962
16th to endNight
31%310%20%23%9%
1719
May1st to 15thNight
33%412%18%22%9%
1620
16th to endNight
27%5%17%27%19%3
1685
June1st to 15thNight
18%5%13%34%23%5%
1620
16th to endNight
20%5%12%29%25%6%
1620
July1st to 15thNight
22%5%13%36%18%3
1530
16th to endNight
14%417%36%23%2
1594
August1st to 15thNight
14%212%33%29%6%
1610
16th to endNight
26%5%11%33%17%4
1869
September1st to 15thNight
29%310%22%22%10%
1980
16th to endNight
24%38%25%26%11%
1980
October1st to 15thNight
25%39%23%20%16%
2070
16th to endNight
22%1417%31%22%
2304
November1st to 15thNight
27%27%25%23%12%
2293
16th to endNight
29%25%16%33%12%
2535
December1st to 15thNight
35%37%20%23%9%
2535
16th to endNight
38%27%21%21%8%
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%10%31%32%12%
135
16th to endDay
11%6%43%22%13%3
144
February1st to 15thDay
12%6%42%26%11%
130
16th to endDay
13%448%25%7%
81
March1st to 15thDay
23%10%35%24%5%1
90
16th to endDay
7%5%41%28%13%4
96
April1st to 15thDay
12%10%27%34%15%
105
16th to endDay
18%8%34%25%11%2
348
May1st to 15thDay
17%7%33%27%10%3
468
16th to endDay
14%328%30%19%3
517
June1st to 15thDay
6%210%38%32%10%
495
16th to endDay
7%210%31%33%15%
495
July1st to 15thDay
5%15%33%40%13%
475
16th to endDay
2315%51%26%
515
August1st to 15thDay
4223%49%19%
493
16th to endDay
11%428%39%16%
370
September1st to 15thDay
2112%45%37%
135
16th to endDay
7%220%43%25%
135
October1st to 15thDay
114%25%42%14%
135
16th to endDay
11%215%31%32%6%
144
November1st to 15thDay
22%122%28%17%7%
135
16th to endDay
20%8%28%25%14%2
135
December1st to 15thDay
21%5%26%31%12%2
135
16th to endDay
20%9%39%25%5%
144
January1st to 15thNight
12%10%32%36%8%
975
16th to endNight
13%8%37%33%6%
1040
February1st to 15thNight
15%8%37%31%6%
841
16th to endNight
15%10%44%25%3
609
March1st to 15thNight
17%9%35%31%6%
540
16th to endNight
13%8%36%31%9%
576
April1st to 15thNight
10%7%43%31%6%
539
16th to endNight
12%7%37%30%11%
540
May1st to 15thNight
10%6%37%33%9%2
540
16th to endNight
7%228%37%20%1
563
June1st to 15thNight
3115%45%30%3
540
16th to endNight
3111%45%34%4
540
July1st to 15thNight
5%5%42%41%4
510
16th to endNight
21132%53%8%
564
August1st to 15thNight
2234%52%7%
539
16th to endNight
6%435%47%5%
573
September1st to 15thNight
12%6%33%42%3
540
16th to endNight
7%8%40%37%5%
537
October1st to 15thNight
10%119%38%25%4
630
16th to endNight
10%5%28%35%17%2
768
November1st to 15thNight
8%5%29%37%18%1
773
16th to endNight
13%8%32%32%12%1
975
December1st to 15thNight
16%7%32%34%8%
975
16th to endNight
19%7%35%30%6%
1040
Page generated at 2018-02-15 09:58:47. Version ac04

Copyright 2018 A. Danko


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