Clarence Fahnestock Memorial State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Clarence Fahnestock Memorial 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
30%
14947
19%
46792
9%
14916
42%
14916
22%
29930

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
20%
720
20%
2506
8%
716
36%
716
18%
1550
January16th to endNight
19%
768
21%
2619
6%
768
39%
768
18%
1628
February1st to 15thNight
15%
704
17%
2227
3%
701
31%
701
16%
1469
February16th to endNight
19%
631
24%
1893
8%
631
39%
631
20%
1197
March1st to 15thNight
19%
720
18%
2160
7%
720
33%
720
18%
1411
March16th to endNight
21%
768
24%
1992
7%
768
34%
768
22%
1318
April1st to 15thNight
22%
718
17%
1796
4%
718
29%
718
21%
1264
April16th to endNight
24%
687
18%
1767
4%
687
33%
687
24%
1210
May1st to 15thNight
25%
496
18%
1576
8%
496
35%
496
19%
1043
May16th to endNight
39%
374
15%
1497
12%
374
47%
374
19%
922
June1st to 15thNight
39%
360
13%
1440
10%
360
50%
360
18%
908
June16th to endNight
50%
360
14%
1440
15%
360
59%
360
26%
810
July1st to 15thNight
50%
340
13%
1360
16%
340
54%
340
22%
815
July16th to endNight
53%
376
15%
1418
18%
354
59%
354
23%
843
August1st to 15thNight
52%
525
18%
1596
12%
523
57%
523
30%
971
August16th to endNight
56%
764
18%
1910
10%
764
58%
764
32%
1290
September1st to 15thNight
44%
707
23%
1768
11%
707
49%
707
34%
1145
September16th to endNight
48%
657
26%
1812
18%
657
54%
657
34%
1109
October1st to 15thNight
35%
660
22%
1922
13%
660
45%
660
26%
1228
October16th to endNight
26%
704
18%
2214
7%
704
40%
704
22%
1439
November1st to 15thNight
31%
700
22%
2277
10%
700
47%
700
23%
1410
November16th to endNight
26%
720
20%
2394
11%
720
39%
720
18%
1533
December1st to 15thNight
24%
720
16%
2520
7%
720
36%
720
15%
1649
December16th to endNight
16%
768
18%
2688
4%
768
32%
768
15%
1768

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
16%6%25%42445%7%38%
47873
Night
16%6%25%42445%6%40%
46962
Cloud CoverDay
16%6%25%43445%7%38%
47882
Night
16%6%2442445%6%41%
46968
TransparencyDay
43%411%22%14%1
47561
Night
42%412%23%15%1
46792
SeeingDay
21%13%27%22%11%3
5749
Night
20%13%30%25%9%
14948

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
14%5%35%5%35%5%5%6%38%
1432
16th to endDay
13%8%26%43445%7%39%
1602
February1st to 15thDay
15%8%36%6%34448%35%
1633
16th to endDay
15%6%25%425%447%38%
1580
March1st to 15thDay
17%7%35%5%2445%7%34%
1790
16th to endDay
17%7%25%5%24445%40%
2230
April1st to 15thDay
20%6%35%423445%38%
2152
16th to endDay
17%6%24423446%43%
2193
May1st to 15thDay
21%7%35%42445%6%34%
2385
16th to endDay
16%6%35%5%245%5%7%36%
2618
June1st to 15thDay
22%425%325%5%6%7%33%
2520
16th to endDay
12%426%5%35%5%6%8%36%
2520
July1st to 15thDay
11%6%25%5%36%5%5%9%37%
2520
16th to endDay
12%425%6%36%6%6%9%36%
2654
August1st to 15thDay
13%6%245%36%5%6%8%38%
2339
16th to endDay
11%5%244345%5%8%43%
2292
September1st to 15thDay
13%5%244345%46%43%
2112
16th to endDay
13%425%424447%47%
1818
October1st to 15thDay
18%6%25%414336%42%
1705
16th to endDay
18%5%245%35%36%5%39%
1658
November1st to 15thDay
18%5%14423346%44%
1581
16th to endDay
18%6%33424436%42%
1563
December1st to 15thDay
17%7%46%434346%37%
1440
16th to endDay
20%8%344145%47%33%
1536
January1st to 15thNight
16%6%25%42445%6%40%
2506
16th to endNight
14%8%35%43435%6%39%
2619
February1st to 15thNight
14%8%36%5%3445%5%38%
2226
16th to endNight
15%6%25%435%45%6%41%
1893
March1st to 15thNight
19%6%2442346%6%38%
2147
16th to endNight
17%6%34323446%42%
1992
April1st to 15thNight
18%7%25%5%35%446%35%
1796
16th to endNight
17%6%25%423445%42%
1767
May1st to 15thNight
18%6%25%6%2445%6%35%
1576
16th to endNight
16%5%1343445%8%39%
1495
June1st to 15thNight
20%42442445%8%37%
1440
16th to endNight
10%425%42446%10%43%
1440
July1st to 15thNight
12%6%25%43447%7%40%
1440
16th to endNight
10%5%25%5%26%6%6%9%40%
1514
August1st to 15thNight
11%415%325%5%6%7%45%
1606
16th to endNight
13%415%43446%6%43%
1910
September1st to 15thNight
15%414424345%48%
1768
16th to endNight
13%5%23323336%51%
1812
October1st to 15thNight
16%7%34323435%45%
1922
16th to endNight
18%6%25%434346%39%
2214
November1st to 15thNight
16%8%24423346%43%
2277
16th to endNight
17%6%35%5%33446%39%
2394
December1st to 15thNight
20%7%25%5%24446%36%
2520
16th to endNight
19%8%25%4245%5%7%34%
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
14%6%35%5%45%45%6%39%
1432
16th to endDay
13%8%25%43446%7%39%
1602
February1st to 15thDay
15%7%36%6%3345%7%35%
1633
16th to endDay
16%7%25%435%447%40%
1580
March1st to 15thDay
18%7%35%5%245%5%8%34%
1800
16th to endDay
17%8%35%5%24436%40%
2229
April1st to 15thDay
20%7%34323445%39%
2152
16th to endDay
17%5%244235%46%43%
2193
May1st to 15thDay
22%6%25%5%24447%33%
2385
16th to endDay
17%6%26%4345%5%7%36%
2618
June1st to 15thDay
22%4344245%6%7%33%
2520
16th to endDay
12%5%25%6%35%6%5%8%36%
2520
July1st to 15thDay
12%5%25%5%36%5%6%8%37%
2520
16th to endDay
12%5%25%5%36%6%7%8%36%
2654
August1st to 15thDay
13%6%246%345%7%8%38%
2339
16th to endDay
12%5%25%435%45%8%42%
2292
September1st to 15thDay
14%5%15%5%3445%6%42%
2112
16th to endDay
13%4245%3335%6%46%
1818
October1st to 15thDay
19%6%24424435%42%
1705
16th to endDay
18%5%25%425%45%5%39%
1658
November1st to 15thDay
19%5%23323346%45%
1581
16th to endDay
18%6%23424346%42%
1563
December1st to 15thDay
17%7%35%435%345%38%
1440
16th to endDay
20%8%344245%5%6%34%
1536
January1st to 15thNight
17%6%2442345%6%41%
2506
16th to endNight
15%8%3433335%7%40%
2619
February1st to 15thNight
14%8%35%5%34446%38%
2219
16th to endNight
15%5%25%42445%5%42%
1893
March1st to 15thNight
20%5%2442435%7%39%
2160
16th to endNight
16%6%35%424346%43%
1992
April1st to 15thNight
18%7%245%3445%6%36%
1796
16th to endNight
18%6%25%323445%41%
1767
May1st to 15thNight
18%7%35%5%3335%7%36%
1576
16th to endNight
18%5%244345%5%8%38%
1495
June1st to 15thNight
20%5%234245%5%8%38%
1440
16th to endNight
9%5%25%4245%5%8%45%
1440
July1st to 15thNight
12%6%245%346%5%7%41%
1440
16th to endNight
10%5%36%425%6%6%8%40%
1514
August1st to 15thNight
11%5%24425%46%7%44%
1606
16th to endNight
14%4245%2445%8%43%
1910
September1st to 15thNight
15%41432435%5%48%
1768
16th to endNight
14%424313436%51%
1812
October1st to 15thNight
17%6%25%413335%45%
1922
16th to endNight
18%6%25%424446%40%
2214
November1st to 15thNight
16%7%34323445%44%
2277
16th to endNight
17%6%25%42435%6%40%
2394
December1st to 15thNight
20%7%35%42445%6%36%
2520
16th to endNight
20%8%244245%5%6%35%
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
42%5%13%24%11%3
1433
16th to endDay
42%313%25%13%1
1602
February1st to 15thDay
47%411%21%13%1
1636
16th to endDay
44%211%25%13%1
1580
March1st to 15thDay
48%214%22%10%1
1800
16th to endDay
45%39%19%18%3
2230
April1st to 15thDay
46%310%21%14%3
2152
16th to endDay
41%48%23%19%2
2193
May1st to 15thDay
49%5%8%20%13%2
2385
16th to endDay
45%7%13%19%12%1
2622
June1st to 15thDay
47%6%13%21%10%1
2520
16th to endDay
42%7%12%24%11%
2520
July1st to 15thDay
42%6%11%21%15%1
2371
16th to endDay
41%6%14%22%13%2
2487
August1st to 15thDay
41%6%14%22%15%
2325
16th to endDay
38%5%10%27%17%
2292
September1st to 15thDay
40%5%9%22%19%1
2112
16th to endDay
37%47%25%22%2
1818
October1st to 15thDay
43%410%22%16%2
1705
16th to endDay
44%311%25%13%1
1658
November1st to 15thDay
40%314%21%17%3
1581
16th to endDay
42%311%27%13%1
1563
December1st to 15thDay
47%316%19%11%
1440
16th to endDay
49%414%21%9%
1536
January1st to 15thNight
42%314%23%12%2
2506
16th to endNight
43%312%24%14%2
2619
February1st to 15thNight
46%414%21%12%2
2227
16th to endNight
41%210%24%17%2
1893
March1st to 15thNight
44%314%21%13%2
2160
16th to endNight
42%310%22%17%3
1992
April1st to 15thNight
47%310%21%14%2
1796
16th to endNight
43%48%21%19%2
1767
May1st to 15thNight
46%410%20%15%2
1576
16th to endNight
42%6%17%18%13%1
1497
June1st to 15thNight
43%6%14%20%12%1
1440
16th to endNight
34%6%15%28%13%1
1440
July1st to 15thNight
40%6%13%24%14%2
1360
16th to endNight
38%6%15%23%13%2
1418
August1st to 15thNight
35%6%14%27%15%1
1596
16th to endNight
38%6%11%23%19%1
1910
September1st to 15thNight
37%411%27%17%
1768
16th to endNight
34%47%23%28%1
1812
October1st to 15thNight
41%311%23%17%2
1922
16th to endNight
44%313%24%13%
2214
November1st to 15thNight
41%311%22%17%3
2277
16th to endNight
45%312%25%11%2
2394
December1st to 15thNight
47%414%21%11%
2520
16th to endNight
47%413%22%11%
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
21%31%25%16%5%
60
16th to endDay
18%25%37%17%1
75
February1st to 15thDay
22%30%28%18%
149
16th to endDay
21%23%31%20%2
239
March1st to 15thDay
26%21%30%17%4
270
16th to endDay
23%21%33%13%5%2
288
April1st to 15thDay
27%16%29%18%7%
270
16th to endDay
23%14%31%16%11%2
270
May1st to 15thDay
36%12%23%16%6%3
288
16th to endDay
21%9%26%26%13%1
331
June1st to 15thDay
25%9%26%23%13%1
315
16th to endDay
16%11%30%23%15%2
315
July1st to 15thDay
16%7%29%29%13%3
305
16th to endDay
15%5%21%33%20%3
326
August1st to 15thDay
17%5%19%32%18%6%
313
16th to endDay
14%420%28%21%11%
332
September1st to 15thDay
14%12%26%22%13%11%
299
16th to endDay
16%5%25%21%13%16%
254
October1st to 15thDay
23%7%21%26%15%4
255
16th to endDay
20%15%31%23%9%
253
November1st to 15thDay
22%10%27%24%12%2
235
16th to endDay
22%22%26%20%6%2
183
December1st to 15thDay
20%30%30%11%8%
60
16th to endDay
32%26%31%9%
64
January1st to 15thNight
20%19%34%22%4
720
16th to endNight
21%18%34%22%1
768
February1st to 15thNight
20%17%40%19%1
704
16th to endNight
20%20%35%19%2
631
March1st to 15thNight
24%21%31%20%2
720
16th to endNight
21%22%30%20%5%
768
April1st to 15thNight
23%17%34%20%3
718
16th to endNight
21%14%35%21%5%
687
May1st to 15thNight
23%13%34%23%6%
496
16th to endNight
21%6%26%33%10%1
375
June1st to 15thNight
21%6%26%33%11%
360
16th to endNight
11%229%42%13%
360
July1st to 15thNight
18%222%38%16%
340
16th to endNight
11%223%38%22%1
376
August1st to 15thNight
15%121%40%19%1
525
16th to endNight
16%315%35%25%2
764
September1st to 15thNight
17%5%26%34%14%2
707
16th to endNight
17%5%23%28%21%3
657
October1st to 15thNight
19%10%27%26%13%1
660
16th to endNight
24%11%33%23%6%
704
November1st to 15thNight
20%13%29%25%9%1
700
16th to endNight
21%17%28%21%9%
720
December1st to 15thNight
26%14%29%22%6%
720
16th to endNight
26%18%35%17%2
768
Page generated at 2017-09-13 07:39:26. Version ac04

Copyright 2017 A. Danko


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