Meridian (Key Field Airport)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Meridian (Key Field Airport) clear sky chart from 2005-11-05 to 2017-12-04.

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
50%
15436
25%
47679
18%
15393
58%
15393
31%
28442

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
28%
791
27%
2257
10%
787
43%
787
28%
1399
January16th to endNight
23%
768
26%
2304
9%
768
38%
768
23%
1509
February1st to 15thNight
31%
704
24%
2112
11%
701
44%
701
26%
1321
February16th to endNight
26%
631
26%
1893
9%
631
38%
631
26%
1184
March1st to 15thNight
31%
720
21%
2160
10%
720
40%
720
27%
1349
March16th to endNight
39%
576
25%
1986
18%
576
50%
576
28%
1122
April1st to 15thNight
39%
539
24%
1797
16%
539
51%
539
28%
1038
April16th to endNight
48%
540
28%
1800
22%
540
60%
540
36%
960
May1st to 15thNight
53%
539
21%
1791
16%
539
62%
539
33%
1021
May16th to endNight
66%
561
25%
1682
21%
561
70%
561
38%
963
June1st to 15thNight
71%
540
16%
1614
15%
540
72%
540
31%
1024
June16th to endNight
73%
540
21%
1440
18%
540
74%
540
38%
887
July1st to 15thNight
78%
510
17%
1404
16%
510
79%
510
36%
877
July16th to endNight
78%
564
14%
1772
17%
531
79%
531
29%
1070
August1st to 15thNight
81%
539
16%
1788
19%
536
81%
536
33%
1030
August16th to endNight
73%
573
19%
1910
23%
573
73%
573
25%
1219
September1st to 15thNight
67%
552
22%
1812
25%
552
69%
552
29%
1107
September16th to endNight
69%
717
29%
1980
25%
717
71%
717
39%
1154
October1st to 15thNight
60%
720
33%
2010
24%
720
66%
720
41%
1140
October16th to endNight
54%
768
36%
2304
29%
768
62%
768
40%
1242
November1st to 15thNight
52%
760
31%
2441
24%
760
63%
760
38%
1293
November16th to endNight
46%
780
32%
2535
24%
780
58%
780
33%
1394
December1st to 15thNight
37%
736
24%
2391
16%
736
48%
736
26%
1456
December16th to endNight
29%
768
20%
2496
13%
768
38%
768
19%
1683

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%5%25%5%35%5%5%7%41%
48756
Night
11%42442445%7%47%
47884
TransparencyDay
40%410%19%18%5%
48465
Night
34%411%19%20%8%
47681
SeeingDay
13%5%16%24%25%13%
5599
Night
13%6%22%28%23%5%
15439

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
18%7%24422335%44%
1646
16th to endDay
19%6%2332334446%
1920
February1st to 15thDay
15%6%35%424336%43%
1750
16th to endDay
16%7%26%423345%43%
1580
March1st to 15thDay
16%7%35%5%24336%41%
1809
16th to endDay
12%6%25%5%245%5%6%44%
2236
April1st to 15thDay
13%5%244345%5%7%43%
2151
16th to endDay
9%5%245%25%5%5%7%46%
2160
May1st to 15thDay
12%425%5%45%5%5%7%41%
2158
16th to endDay
8%426%6%45%5%6%8%40%
2431
June1st to 15thDay
7%425%8%47%6%6%9%35%
2340
16th to endDay
5%425%7%5%7%6%9%10%36%
2520
July1st to 15thDay
8%437%8%5%7%7%9%9%29%
2466
16th to endDay
8%436%8%5%9%7%8%10%28%
2276
August1st to 15thDay
6%426%7%5%8%7%8%10%32%
2160
16th to endDay
12%5%26%6%5%7%6%7%8%31%
2292
September1st to 15thDay
12%5%26%8%36%5%6%6%36%
2136
16th to endDay
12%4245%23446%49%
1980
October1st to 15thDay
8%5%24423345%55%
1947
16th to endDay
10%313322336%58%
1920
November1st to 15thDay
10%5%14423435%55%
1744
16th to endDay
13%5%1332234453%
1755
December1st to 15thDay
14%8%36%42445%6%39%
1651
16th to endDay
19%9%36%423345%37%
1728
January1st to 15thNight
15%6%2432333449%
2257
16th to endNight
19%7%345%1323444%
2304
February1st to 15thNight
15%5%3442435%446%
2103
16th to endNight
16%6%24423345%46%
1893
March1st to 15thNight
16%5%25%424347%44%
2160
16th to endNight
12%423423437%49%
1986
April1st to 15thNight
9%425%425%45%6%49%
1797
16th to endNight
8%32332346%8%52%
1800
May1st to 15thNight
8%5%2442445%9%48%
1790
16th to endNight
6%323425%6%6%9%49%
1682
June1st to 15thNight
4325%5%46%8%8%10%39%
1614
16th to endNight
5%3345%35%5%7%11%45%
1440
July1st to 15thNight
4325%6%35%7%8%12%42%
1487
16th to endNight
3225%6%37%7%10%11%38%
1892
August1st to 15thNight
4214445%6%8%14%41%
1800
16th to endNight
7%425%5%45%5%7%11%38%
1910
September1st to 15thNight
11%4245%2447%8%44%
1812
16th to endNight
7%4245%3346%7%51%
1980
October1st to 15thNight
8%413424447%55%
2010
16th to endNight
11%32321233460%
2304
November1st to 15thNight
9%413423346%57%
2441
16th to endNight
12%5%14323246%54%
2535
December1st to 15thNight
15%6%24424336%45%
2391
16th to endNight
17%10%36%5%23345%37%
2496

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
43%25%16%23%8%
1647
16th to endDay
42%25%17%24%8%
1920
February1st to 15thDay
42%25%21%20%7%
1752
16th to endDay
44%25%18%21%8%
1580
March1st to 15thDay
45%28%17%20%5%
1809
16th to endDay
39%48%20%22%4
2238
April1st to 15thDay
39%38%20%22%6%
2151
16th to endDay
35%48%23%23%3
2160
May1st to 15thDay
41%5%10%17%20%4
2158
16th to endDay
39%5%15%24%15%1
2435
June1st to 15thDay
41%6%13%23%13%1
2340
16th to endDay
37%8%14%23%13%2
2520
July1st to 15thDay
44%8%18%18%8%2
2321
16th to endDay
45%9%19%19%6%
2133
August1st to 15thDay
41%8%18%19%10%2
2148
16th to endDay
45%9%14%16%10%3
2292
September1st to 15thDay
45%6%12%18%12%5%
2136
16th to endDay
34%49%22%21%7%
1980
October1st to 15thDay
31%37%20%25%12%
1947
16th to endDay
28%2314%36%14%
1920
November1st to 15thDay
32%27%18%28%10%
1744
16th to endDay
33%27%16%26%13%
1755
December1st to 15thDay
44%39%19%16%7%
1651
16th to endDay
49%27%19%15%5%
1728
January1st to 15thNight
39%26%17%27%8%
2257
16th to endNight
45%2315%24%8%
2304
February1st to 15thNight
40%26%17%21%10%
2112
16th to endNight
40%35%17%22%10%
1893
March1st to 15thNight
40%29%17%22%7%
2160
16th to endNight
34%39%21%23%5%
1986
April1st to 15thNight
35%310%19%20%10%
1797
16th to endNight
28%49%24%25%7%
1800
May1st to 15thNight
31%5%12%22%19%7%
1791
16th to endNight
28%6%15%25%20%3
1684
June1st to 15thNight
34%8%15%24%14%1
1614
16th to endNight
29%7%19%22%16%3
1440
July1st to 15thNight
28%10%24%24%7%3
1404
16th to endNight
30%11%25%24%6%1
1772
August1st to 15thNight
28%10%25%21%11%3
1788
16th to endNight
37%9%20%16%11%3
1910
September1st to 15thNight
36%6%16%21%14%5%
1812
16th to endNight
29%5%11%22%22%8%
1980
October1st to 15thNight
28%5%8%19%22%16%
2010
16th to endNight
28%2314%30%20%
2304
November1st to 15thNight
28%37%18%28%13%
2441
16th to endNight
32%25%19%24%16%
2535
December1st to 15thNight
40%29%20%20%5%
2391
16th to endNight
49%36%15%18%5%
2496

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
23%17%27%22%5%3
90
16th to endDay
17%28%38%12%21
96
February1st to 15thDay
24%16%42%10%6%
90
16th to endDay
23%14%34%27%
81
March1st to 15thDay
25%24%34%14%1
90
16th to endDay
20%9%28%27%13%
222
April1st to 15thDay
21%11%22%26%14%3
270
16th to endDay
13%8%25%32%17%2
270
May1st to 15thDay
15%6%25%25%19%7%
288
16th to endDay
10%421%28%19%15%
331
June1st to 15thDay
10%111%27%31%17%
315
16th to endDay
6%38%32%33%16%
495
July1st to 15thDay
7%1424%40%20%
469
16th to endDay
9%314%38%34%
326
August1st to 15thDay
7%16%21%33%29%
313
16th to endDay
13%321%36%25%
332
September1st to 15thDay
11%39%26%30%18%
315
16th to endDay
10%28%27%36%14%
314
October1st to 15thDay
12%318%26%28%10%
282
16th to endDay
13%9%29%21%19%6%
144
November1st to 15thDay
17%7%37%25%10%1
135
16th to endDay
11%11%35%20%15%5%
135
December1st to 15thDay
22%14%37%16%9%2
100
16th to endDay
28%16%23%23%5%2
96
January1st to 15thNight
19%13%34%24%8%
791
16th to endNight
24%12%35%23%4
768
February1st to 15thNight
20%12%32%30%4
704
16th to endNight
19%15%35%25%3
631
March1st to 15thNight
19%12%34%27%7%
720
16th to endNight
13%10%33%27%14%
576
April1st to 15thNight
11%10%34%26%15%
539
16th to endNight
10%6%29%38%14%
540
May1st to 15thNight
10%324%37%21%1
540
16th to endNight
8%115%34%34%6%
563
June1st to 15thNight
6%19%34%40%7%
540
16th to endNight
5%18%26%41%15%
540
July1st to 15thNight
4329%46%15%
510
16th to endNight
31426%47%17%
564
August1st to 15thNight
6%220%50%18%
539
16th to endNight
9%5%22%44%17%
573
September1st to 15thNight
13%27%23%41%11%
552
16th to endNight
10%18%34%39%5%
717
October1st to 15thNight
10%221%26%34%5%
720
16th to endNight
13%6%21%30%24%3
768
November1st to 15thNight
11%5%26%32%19%4
760
16th to endNight
15%8%25%30%17%1
780
December1st to 15thNight
19%8%29%29%12%
736
16th to endNight
24%11%30%27%6%
768
Page generated at 2017-12-05 09:19:01. Version ac04

Copyright 2017 A. Danko


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