Rocky Gap State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rocky Gap State Park clear sky chart from 2005-11-05 to

2017-09-12
.

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
37%
15186
18%
46862
10%
15146
46%
15146
21%
30564

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
18%
717
16%
2368
6%
716
31%
716
11%
1637
January16th to endNight
16%
768
15%
2496
4%
768
31%
768
13%
1736
February1st to 15thNight
18%
704
15%
2287
5%
701
31%
701
14%
1505
February16th to endNight
19%
631
17%
1944
5%
631
33%
631
13%
1343
March1st to 15thNight
23%
720
18%
1980
8%
720
34%
720
19%
1355
March16th to endNight
25%
768
18%
2112
8%
768
34%
768
20%
1430
April1st to 15thNight
25%
718
15%
1814
5%
718
31%
718
21%
1284
April16th to endNight
39%
669
18%
1749
8%
669
44%
669
25%
1186
May1st to 15thNight
41%
540
17%
1620
10%
540
47%
540
20%
1106
May16th to endNight
51%
411
17%
1534
17%
411
57%
411
21%
942
June1st to 15thNight
54%
360
18%
1440
18%
360
62%
360
24%
830
June16th to endNight
56%
360
18%
1440
19%
360
63%
360
26%
815
July1st to 15thNight
61%
385
12%
1405
13%
385
63%
385
22%
877
July16th to endNight
66%
564
16%
1595
12%
531
70%
531
35%
919
August1st to 15thNight
65%
539
18%
1609
14%
536
66%
536
31%
1002
August16th to endNight
66%
696
22%
1842
16%
696
67%
696
37%
1144
September1st to 15thNight
55%
707
24%
1768
14%
707
59%
707
33%
1142
September16th to endNight
54%
657
21%
1840
17%
657
57%
657
29%
1178
October1st to 15thNight
46%
660
22%
1980
18%
660
54%
660
26%
1245
October16th to endNight
33%
704
25%
2112
12%
704
49%
704
25%
1293
November1st to 15thNight
40%
700
23%
2199
16%
700
50%
700
25%
1354
November16th to endNight
30%
720
17%
2520
9%
720
41%
720
15%
1657
December1st to 15thNight
25%
720
13%
2520
6%
720
35%
720
12%
1743
December16th to endNight
21%
768
14%
2688
5%
768
34%
768
12%
1841

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
13%6%36%5%35%5%5%7%36%
47780
Night
13%5%25%5%3445%7%40%
47049
Cloud CoverDay
13%6%36%5%35%5%5%7%37%
47790
Night
13%6%25%5%35%45%7%41%
47053
TransparencyDay
44%7%13%19%12%1
47485
Night
41%7%13%22%13%2
46862
SeeingDay
20%12%23%21%15%6%
5530
Night
18%13%24%28%13%1
15190

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
13%7%5%9%6%45%5%46%29%
1567
16th to endDay
13%11%5%7%7%25%45%5%30%
1728
February1st to 15thDay
12%10%48%7%45%436%32%
1575
16th to endDay
11%8%411%7%2435%6%33%
1527
March1st to 15thDay
14%10%36%5%34445%37%
1969
16th to endDay
15%7%46%6%3435%8%34%
2112
April1st to 15thDay
14%8%46%43445%6%36%
2134
16th to endDay
17%6%245%34448%39%
2220
May1st to 15thDay
19%7%25%5%26%5%6%6%32%
2331
16th to endDay
16%6%25%5%35%5%6%7%35%
2578
June1st to 15thDay
11%325%445%6%7%9%39%
2520
16th to endDay
10%5%25%6%36%5%7%10%36%
2520
July1st to 15thDay
10%425%6%46%7%6%8%36%
2467
16th to endDay
7%325%6%47%7%8%10%35%
2465
August1st to 15thDay
10%426%5%47%6%7%9%33%
2340
16th to endDay
11%4345%35%5%6%8%41%
2348
September1st to 15thDay
14%5%15%42445%6%44%
2112
16th to endDay
16%6%25%5%345%46%40%
1786
October1st to 15thDay
19%424334346%43%
1650
16th to endDay
14%6%35%5%25%5%46%40%
1760
November1st to 15thDay
9%6%26%33445%6%46%
1655
16th to endDay
17%9%345%35%346%36%
1440
December1st to 15thDay
17%7%47%6%35%5%5%6%29%
1440
16th to endDay
17%10%5%9%5%35%445%27%
1536
January1st to 15thNight
15%7%36%6%35%5%5%6%33%
2368
16th to endNight
13%9%37%6%35%45%6%33%
2496
February1st to 15thNight
12%7%35%5%35%45%7%37%
2285
16th to endNight
9%7%36%7%36%5%7%7%33%
1944
March1st to 15thNight
15%6%25%4335%5%8%39%
1968
16th to endNight
16%7%3442435%5%42%
2112
April1st to 15thNight
14%8%35%5%245%5%6%38%
1814
16th to endNight
15%5%24434448%42%
1749
May1st to 15thNight
19%5%35%425%45%7%36%
1620
16th to endNight
13%5%235%25%46%8%43%
1532
June1st to 15thNight
11%213425%6%5%9%46%
1440
16th to endNight
9%215%5%345%7%9%45%
1440
July1st to 15thNight
9%326%6%4446%9%42%
1489
16th to endNight
6%3235%25%5%8%11%46%
1703
August1st to 15thNight
7%325%5%35%6%6%8%45%
1620
16th to endNight
10%32442345%8%50%
1842
September1st to 15thNight
13%424434247%49%
1768
16th to endNight
15%5%23423446%46%
1840
October1st to 15thNight
16%42443335%5%45%
1980
16th to endNight
15%31442436%7%46%
2112
November1st to 15thNight
12%6%34333345%47%
2199
16th to endNight
16%5%35%5%36%5%5%6%37%
2520
December1st to 15thNight
15%7%46%5%35%5%5%6%32%
2520
16th to endNight
14%8%37%6%35%45%7%33%
2688

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%7%5%9%6%36%5%5%6%30%
1567
16th to endDay
14%11%5%7%6%35%445%30%
1728
February1st to 15thDay
13%10%38%6%36%446%32%
1575
16th to endDay
11%7%5%10%6%34445%35%
1527
March1st to 15thDay
15%9%45%5%3444438%
1980
16th to endDay
15%8%46%6%34447%35%
2111
April1st to 15thDay
14%8%46%5%34446%36%
2134
16th to endDay
17%6%24435%347%39%
2220
May1st to 15thDay
18%7%25%5%36%5%6%7%32%
2331
16th to endDay
15%6%25%5%35%6%5%7%35%
2578
June1st to 15thDay
11%3245%46%6%7%9%39%
2520
16th to endDay
9%5%25%6%36%5%7%10%36%
2520
July1st to 15thDay
10%5%25%6%36%7%6%9%36%
2467
16th to endDay
7%325%6%47%7%7%10%36%
2465
August1st to 15thDay
10%435%6%38%6%6%8%35%
2340
16th to endDay
11%4245%35%5%7%7%42%
2348
September1st to 15thDay
14%5%145%2345%7%43%
2112
16th to endDay
15%6%26%5%25%5%46%40%
1786
October1st to 15thDay
18%5%14324346%43%
1650
16th to endDay
13%6%35%5%245%5%6%41%
1760
November1st to 15thDay
10%5%35%425%35%6%47%
1655
16th to endDay
18%9%345%3445%5%36%
1440
December1st to 15thDay
17%6%5%7%6%35%5%6%5%30%
1440
16th to endDay
17%10%49%6%35%435%28%
1536
January1st to 15thNight
15%7%46%6%35%6%5%6%33%
2368
16th to endNight
14%10%36%5%36%45%5%34%
2496
February1st to 15thNight
12%7%346%35%45%7%38%
2278
16th to endNight
10%7%36%7%36%6%6%7%33%
1944
March1st to 15thNight
15%6%245%245%5%7%39%
1980
16th to endNight
16%7%3432445%6%42%
2112
April1st to 15thNight
15%7%26%5%2445%6%38%
1814
16th to endNight
16%423434447%43%
1749
May1st to 15thNight
17%6%35%325%45%7%36%
1619
16th to endNight
13%5%23435%45%8%43%
1532
June1st to 15thNight
11%213325%5%5%9%47%
1440
16th to endNight
8%3246%245%8%9%45%
1440
July1st to 15thNight
8%325%5%35%5%6%9%42%
1489
16th to endNight
5%3235%25%6%8%11%45%
1703
August1st to 15thNight
7%425%5%35%5%6%8%44%
1620
16th to endNight
10%41432445%7%50%
1842
September1st to 15thNight
13%424424346%49%
1768
16th to endNight
15%5%2332445%5%46%
1840
October1st to 15thNight
16%42442335%6%45%
1980
16th to endNight
15%31342445%7%47%
2112
November1st to 15thNight
12%7%34324346%47%
2199
16th to endNight
15%6%35%5%35%5%5%6%37%
2520
December1st to 15thNight
15%7%46%5%46%5%5%5%33%
2520
16th to endNight
14%7%46%6%35%45%7%33%
2688

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
52%6%12%19%8%1
1568
16th to endDay
54%6%13%17%7%1
1728
February1st to 15thDay
52%5%14%17%8%
1577
16th to endDay
50%416%18%9%
1527
March1st to 15thDay
48%5%13%21%10%1
1980
16th to endDay
48%6%13%19%11%1
2112
April1st to 15thDay
48%5%11%17%15%1
2134
16th to endDay
44%5%9%20%15%4
2220
May1st to 15thDay
49%8%12%17%11%
2331
16th to endDay
45%9%13%19%10%2
2582
June1st to 15thDay
37%11%13%21%14%1
2520
16th to endDay
39%11%16%19%11%1
2520
July1st to 15thDay
41%12%12%18%12%2
2322
16th to endDay
37%11%16%19%13%1
2310
August1st to 15thDay
42%10%15%19%11%
2327
16th to endDay
37%9%14%24%12%2
2348
September1st to 15thDay
38%7%11%20%18%2
2112
16th to endDay
44%6%9%20%17%1
1786
October1st to 15thDay
40%6%13%24%12%2
1650
16th to endDay
41%7%10%25%13%
1760
November1st to 15thDay
37%5%13%20%18%5%
1655
16th to endDay
47%6%13%19%12%
1440
December1st to 15thDay
52%8%13%16%8%
1440
16th to endDay
58%5%11%16%7%
1536
January1st to 15thNight
48%7%13%16%12%2
2368
16th to endNight
49%5%13%21%8%1
2496
February1st to 15thNight
44%7%15%20%11%
2287
16th to endNight
46%8%13%21%10%
1944
March1st to 15thNight
43%6%14%25%8%1
1980
16th to endNight
42%6%14%20%13%1
2112
April1st to 15thNight
44%6%11%20%14%2
1814
16th to endNight
40%7%11%20%15%5%
1749
May1st to 15thNight
45%7%11%20%12%2
1620
16th to endNight
38%8%15%21%14%1
1534
June1st to 15thNight
32%10%13%29%13%
1440
16th to endNight
32%8%16%25%14%1
1440
July1st to 15thNight
38%10%15%20%11%4
1405
16th to endNight
26%10%20%24%15%2
1595
August1st to 15thNight
34%8%15%23%17%1
1609
16th to endNight
30%7%12%28%18%2
1842
September1st to 15thNight
35%6%13%21%20%2
1768
16th to endNight
37%6%10%23%19%1
1840
October1st to 15thNight
38%6%12%24%16%1
1980
16th to endNight
34%6%11%29%16%
2112
November1st to 15thNight
38%5%10%21%17%6%
2199
16th to endNight
44%6%11%20%14%2
2520
December1st to 15thNight
49%7%13%19%9%
2520
16th to endNight
48%7%17%18%8%
2688

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
32%22%25%8%8%2
83
16th to endDay
41%18%22%13%3
96
February1st to 15thDay
33%33%27%5%
90
16th to endDay
26%24%31%15%2
153
March1st to 15thDay
24%21%24%24%3
270
16th to endDay
25%18%29%17%6%3
288
April1st to 15thDay
22%19%20%24%9%2
270
16th to endDay
21%15%23%16%15%7%
270
May1st to 15thDay
33%13%19%14%12%5%
288
16th to endDay
20%12%19%23%12%11%
331
June1st to 15thDay
15%9%27%23%18%5%
315
16th to endDay
13%12%30%22%15%5%
315
July1st to 15thDay
15%5%29%23%19%6%
305
16th to endDay
7%320%30%26%10%
326
August1st to 15thDay
15%319%22%25%12%
313
16th to endDay
12%316%25%22%20%
332
September1st to 15thDay
16%6%19%18%24%14%
299
16th to endDay
22%417%20%25%9%
254
October1st to 15thDay
23%5%19%22%23%4
255
16th to endDay
15%18%26%27%10%1
272
November1st to 15thDay
13%14%25%25%19%1
221
16th to endDay
30%18%25%15%10%1
60
December1st to 15thDay
36%21%16%13%10%1
60
16th to endDay
32%17%31%17%1
64
January1st to 15thNight
25%22%29%19%4
720
16th to endNight
23%22%32%20%
768
February1st to 15thNight
21%22%32%21%1
704
16th to endNight
21%23%32%20%2
631
March1st to 15thNight
24%17%30%23%4
720
16th to endNight
21%19%30%19%7%
768
April1st to 15thNight
21%18%32%22%5%
718
16th to endNight
21%11%23%30%12%
669
May1st to 15thNight
22%9%22%30%14%
540
16th to endNight
18%6%17%35%20%2
412
June1st to 15thNight
11%324%36%23%
360
16th to endNight
9%222%45%19%
360
July1st to 15thNight
11%215%41%28%1
385
16th to endNight
6%116%35%35%3
564
August1st to 15thNight
10%114%42%26%4
539
16th to endNight
13%111%35%34%3
696
September1st to 15thNight
14%5%17%29%29%3
707
16th to endNight
18%5%17%28%26%3
657
October1st to 15thNight
19%8%20%28%20%2
660
16th to endNight
19%16%26%27%9%
704
November1st to 15thNight
16%14%23%31%13%1
700
16th to endNight
23%18%22%25%8%
720
December1st to 15thNight
23%17%29%24%5%
720
16th to endNight
21%20%30%25%1
768
Page generated at 2017-09-13 07:39:11. Version ac04

Copyright 2017 A. Danko


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