Finger Lakes Regional Airport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Finger Lakes Regional Airport clear sky chart from 2005-11-05 to 2017-12-02.

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
31%
15161
12%
47822
8%
15130
35%
15130
15%
35404

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
13%
719
5%
2506
3%
716
15%
716
5%
2155
January16th to endNight
13%
768
7%
2544
3%
768
19%
768
6%
2153
February1st to 15thNight
12%
703
6%
2287
2%
701
18%
701
6%
1923
February16th to endNight
16%
631
9%
1950
5%
631
22%
631
9%
1572
March1st to 15thNight
20%
720
11%
2049
6%
720
25%
720
12%
1636
March16th to endNight
27%
768
15%
2064
8%
768
32%
768
17%
1547
April1st to 15thNight
26%
718
12%
1796
4%
718
29%
718
17%
1390
April16th to endNight
34%
690
18%
1770
8%
690
37%
690
26%
1226
May1st to 15thNight
41%
405
17%
1485
14%
405
48%
405
17%
1008
May16th to endNight
48%
374
16%
1497
17%
374
54%
374
21%
906
June1st to 15thNight
45%
360
12%
1440
15%
360
51%
360
18%
929
June16th to endNight
52%
360
12%
1440
16%
360
57%
360
23%
878
July1st to 15thNight
59%
340
14%
1360
19%
340
63%
340
25%
776
July16th to endNight
59%
391
15%
1432
18%
368
62%
368
25%
836
August1st to 15thNight
56%
539
14%
1609
10%
536
59%
536
30%
1009
August16th to endNight
61%
714
21%
1860
13%
714
62%
714
34%
1196
September1st to 15thNight
50%
720
18%
1800
9%
720
52%
720
28%
1245
September16th to endNight
52%
717
23%
1970
18%
717
54%
717
30%
1275
October1st to 15thNight
35%
720
14%
2160
12%
720
40%
720
19%
1540
October16th to endNight
20%
768
10%
2334
5%
768
27%
768
12%
1838
November1st to 15thNight
25%
760
13%
2505
10%
760
30%
760
14%
1827
November16th to endNight
20%
780
12%
2730
8%
780
26%
780
10%
2067
December1st to 15thNight
14%
728
5%
2546
2%
728
18%
728
6%
2116
December16th to endNight
10%
768
4%
2688
1%
768
13%
768
4%
2356

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
15%9%47%6%35%5%5%7%30%
48629
Night
17%10%47%6%34446%30%
47994
Cloud CoverDay
16%9%47%6%35%45%6%30%
48639
Night
17%10%47%6%34446%30%
47999
TransparencyDay
53%7%11%17%9%
48319
Night
55%6%11%16%9%
47822
SeeingDay
22%11%26%21%12%5%
5774
Night
23%13%26%25%10%1
15164

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
16%14%6%14%9%36%6%4413%
1432
16th to endDay
13%14%6%13%10%5%7%5%4413%
1679
February1st to 15thDay
15%13%9%15%9%45%5%4412%
1575
16th to endDay
18%12%5%11%9%46%5%4416%
1521
March1st to 15thDay
16%14%6%10%7%45%44420%
1897
16th to endDay
18%10%47%6%35%447%28%
2159
April1st to 15thDay
20%10%46%5%35%436%31%
2152
16th to endDay
16%9%25%5%23347%37%
2201
May1st to 15thDay
15%7%37%6%3435%7%35%
2463
16th to endDay
14%6%25%435%5%5%8%37%
2618
June1st to 15thDay
19%7%35%43445%7%33%
2520
16th to endDay
12%5%25%5%36%46%9%37%
2520
July1st to 15thDay
10%4246%35%6%6%8%40%
2520
16th to endDay
11%5%35%5%47%6%7%9%34%
2638
August1st to 15thDay
12%5%26%6%447%7%8%34%
2340
16th to endDay
12%5%25%5%46%6%7%8%35%
2330
September1st to 15thDay
15%7%35%42445%6%39%
2160
16th to endDay
14%5%26%5%35%447%41%
1987
October1st to 15thDay
17%9%35%5%25%35%6%34%
1800
16th to endDay
23%11%46%5%34446%23%
1890
November1st to 15thDay
15%10%46%7%45%45%6%29%
1680
16th to endDay
18%12%48%6%345%5%7%23%
1560
December1st to 15thDay
18%17%5%10%7%34336%18%
1451
16th to endDay
20%19%7%10%8%4434411%
1536
January1st to 15thNight
18%17%6%12%8%45%43315%
2506
16th to endNight
15%16%7%10%9%45%445%15%
2544
February1st to 15thNight
15%14%8%13%8%45%43416%
2285
16th to endNight
16%12%6%11%7%45%5%4420%
1950
March1st to 15thNight
20%11%5%8%8%24435%25%
2037
16th to endNight
18%11%47%43445%5%31%
2064
April1st to 15thNight
21%8%36%5%35%445%29%
1796
16th to endNight
17%7%25%5%2335%6%41%
1770
May1st to 15thNight
17%6%35%5%345%46%36%
1485
16th to endNight
11%5%25%5%3446%8%40%
1495
June1st to 15thNight
17%6%35%43446%7%36%
1440
16th to endNight
11%5%245%35%5%5%8%42%
1440
July1st to 15thNight
6%325%5%36%5%6%9%44%
1440
16th to endNight
11%415%5%35%5%6%8%44%
1529
August1st to 15thNight
9%415%5%245%6%8%44%
1620
16th to endNight
10%42443445%6%48%
1860
September1st to 15thNight
15%5%25%424447%41%
1800
16th to endNight
13%6%24425%45%7%44%
1970
October1st to 15thNight
20%8%35%5%23446%34%
2160
16th to endNight
25%9%48%5%33345%24%
2334
November1st to 15thNight
17%12%46%6%34346%30%
2505
16th to endNight
18%14%47%5%34446%26%
2730
December1st to 15thNight
21%15%6%8%7%35%44417%
2546
16th to endNight
22%18%6%10%7%35%43412%
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
17%14%7%13%9%36%5%3313%
1432
16th to endDay
13%14%7%12%11%5%7%445%12%
1679
February1st to 15thDay
15%14%9%14%10%35%44412%
1575
16th to endDay
18%12%6%11%9%46%5%3417%
1521
March1st to 15thDay
17%14%6%9%7%35%44419%
1908
16th to endDay
18%10%46%7%25%347%28%
2158
April1st to 15thDay
20%10%46%434445%31%
2152
16th to endDay
18%8%24423346%38%
2201
May1st to 15thDay
16%6%36%7%3445%7%35%
2463
16th to endDay
15%5%244345%5%8%38%
2618
June1st to 15thDay
20%7%345%2445%7%33%
2520
16th to endDay
14%425%5%36%46%9%37%
2520
July1st to 15thDay
10%4245%45%5%5%8%41%
2520
16th to endDay
12%435%5%46%6%7%9%35%
2638
August1st to 15thDay
14%425%5%45%6%8%8%35%
2340
16th to endDay
13%425%5%46%6%6%8%36%
2330
September1st to 15thDay
17%6%35%334446%40%
2160
16th to endDay
14%5%35%5%34447%41%
1987
October1st to 15thDay
18%9%26%5%34347%35%
1800
16th to endDay
25%11%36%5%34446%23%
1890
November1st to 15thDay
15%11%36%6%35%5%5%6%29%
1680
16th to endDay
19%12%47%6%35%5%5%6%23%
1560
December1st to 15thDay
18%18%6%9%7%34235%18%
1451
16th to endDay
21%18%8%10%8%3434412%
1536
January1st to 15thNight
19%17%6%12%8%35%43315%
2506
16th to endNight
15%16%7%11%9%45%445%14%
2544
February1st to 15thNight
15%15%7%13%7%45%43416%
2278
16th to endNight
16%13%5%11%7%36%44420%
1950
March1st to 15thNight
21%11%5%8%7%24435%24%
2049
16th to endNight
18%11%5%6%434445%31%
2064
April1st to 15thNight
22%8%46%5%34446%29%
1796
16th to endNight
18%7%25%5%2335%5%41%
1770
May1st to 15thNight
19%7%35%4345%45%36%
1485
16th to endNight
12%5%25%5%345%6%9%40%
1495
June1st to 15thNight
17%5%35%43445%8%36%
1440
16th to endNight
12%4245%35%46%8%41%
1440
July1st to 15thNight
7%3245%45%5%6%9%44%
1440
16th to endNight
11%3245%345%6%7%45%
1529
August1st to 15thNight
9%425%5%346%6%8%44%
1620
16th to endNight
11%4144245%47%48%
1860
September1st to 15thNight
15%6%25%424447%42%
1800
16th to endNight
14%6%143245%5%6%44%
1970
October1st to 15thNight
21%7%26%423446%34%
2160
16th to endNight
26%10%37%5%33335%24%
2334
November1st to 15thNight
17%11%47%5%24347%30%
2505
16th to endNight
18%14%47%5%34346%26%
2730
December1st to 15thNight
21%16%5%9%6%35%44417%
2546
16th to endNight
23%19%6%10%7%35%43412%
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
73%6%7%7%4
1433
16th to endDay
73%7%10%6%3
1679
February1st to 15thDay
75%6%7%8%2
1577
16th to endDay
70%6%7%10%4
1521
March1st to 15thDay
66%6%10%11%4
1908
16th to endDay
56%5%10%17%9%
2159
April1st to 15thDay
55%411%17%9%1
2152
16th to endDay
46%5%7%20%17%2
2201
May1st to 15thDay
48%7%11%19%11%1
2463
16th to endDay
43%7%14%20%12%1
2622
June1st to 15thDay
48%7%11%20%10%
2520
16th to endDay
41%10%13%22%11%
2520
July1st to 15thDay
38%9%11%25%12%1
2371
16th to endDay
42%11%15%20%9%
2472
August1st to 15thDay
42%10%14%20%10%1
2327
16th to endDay
42%10%12%23%10%
2330
September1st to 15thDay
43%7%10%23%13%1
2160
16th to endDay
43%6%10%24%14%1
1987
October1st to 15thDay
49%7%12%18%11%
1800
16th to endDay
60%7%13%13%4
1890
November1st to 15thDay
53%7%13%15%8%1
1680
16th to endDay
58%9%13%14%3
1560
December1st to 15thDay
69%5%13%9%2
1451
16th to endDay
76%6%8%6%2
1536
January1st to 15thNight
73%6%6%7%4
2506
16th to endNight
71%6%8%10%3
2544
February1st to 15thNight
70%6%7%10%4
2287
16th to endNight
65%5%10%12%5%
1950
March1st to 15thNight
63%5%10%16%4
2049
16th to endNight
55%5%9%15%12%1
2064
April1st to 15thNight
55%6%9%16%10%1
1796
16th to endNight
44%5%10%20%17%2
1770
May1st to 15thNight
47%7%9%18%14%2
1485
16th to endNight
39%7%13%22%13%2
1497
June1st to 15thNight
45%7%12%22%11%
1440
16th to endNight
39%7%13%21%16%1
1440
July1st to 15thNight
33%8%14%23%17%2
1360
16th to endNight
35%8%13%26%13%3
1432
August1st to 15thNight
33%9%16%28%10%
1609
16th to endNight
34%7%13%29%14%1
1860
September1st to 15thNight
41%7%11%22%14%2
1800
16th to endNight
37%6%11%26%16%1
1970
October1st to 15thNight
50%6%10%18%13%
2160
16th to endNight
61%5%13%13%4
2334
November1st to 15thNight
55%6%12%15%8%2
2505
16th to endNight
60%5%12%15%5%
2730
December1st to 15thNight
69%6%11%9%2
2546
16th to endNight
76%6%8%7%1
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
23%21%36%8%10%
60
16th to endDay
31%21%35%10%1
88
February1st to 15thDay
26%32%33%7%
90
16th to endDay
27%18%39%11%2
180
March1st to 15thDay
28%18%25%21%5%
270
16th to endDay
26%18%29%17%7%1
288
April1st to 15thDay
30%15%27%15%10%1
270
16th to endDay
21%15%23%20%13%5%
270
May1st to 15thDay
27%12%21%22%11%3
288
16th to endDay
17%10%32%21%13%3
331
June1st to 15thDay
25%7%27%22%14%1
315
16th to endDay
16%8%34%25%12%2
315
July1st to 15thDay
11%7%22%34%17%6%
305
16th to endDay
13%5%26%27%22%5%
326
August1st to 15thDay
17%5%23%24%18%10%
313
16th to endDay
14%222%23%19%16%
332
September1st to 15thDay
18%10%14%23%20%13%
315
16th to endDay
15%9%19%21%19%14%
314
October1st to 15thDay
25%7%24%20%15%5%
315
16th to endDay
30%14%29%18%6%
328
November1st to 15thDay
27%10%27%24%9%1
244
16th to endDay
26%27%30%14%1
90
December1st to 15thDay
28%19%31%12%6%1
63
16th to endDay
37%21%32%7%
64
January1st to 15thNight
29%22%29%14%3
720
16th to endNight
24%20%34%17%3
768
February1st to 15thNight
23%20%35%16%3
704
16th to endNight
24%19%33%18%3
631
March1st to 15thNight
27%19%26%21%4
720
16th to endNight
24%15%28%23%8%
768
April1st to 15thNight
28%13%27%26%3
718
16th to endNight
22%11%28%27%10%
690
May1st to 15thNight
26%5%19%36%10%1
405
16th to endNight
12%6%26%36%17%
375
June1st to 15thNight
19%7%20%35%18%
360
16th to endNight
15%322%44%12%
360
July1st to 15thNight
10%220%43%21%1
340
16th to endNight
10%321%42%20%1
391
August1st to 15thNight
11%223%36%22%3
539
16th to endNight
13%316%36%26%2
714
September1st to 15thNight
19%5%19%30%21%3
720
16th to endNight
16%6%20%24%25%6%
717
October1st to 15thNight
26%8%25%20%17%1
720
16th to endNight
32%13%28%21%4
768
November1st to 15thNight
27%13%29%21%7%1
760
16th to endNight
26%20%26%18%7%1
780
December1st to 15thNight
32%20%27%17%2
728
16th to endNight
32%20%29%14%2
768
Page generated at 2017-12-03 11:16:49. Version ac04

Copyright 2017 A. Danko


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