Twin Pond
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Twin Pond clear sky chart from 2005-11-05 to 2017-09-22.

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
45%
15935
26%
46779
15%
15889
55%
15889
38%
26296

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
39%
900
27%
2495
12%
895
50%
895
40%
1405
January16th to endNight
40%
960
31%
2496
13%
960
51%
960
42%
1437
February1st to 15thNight
35%
766
20%
2178
8%
762
45%
762
30%
1379
February16th to endNight
36%
632
28%
1894
10%
632
51%
632
34%
1063
March1st to 15thNight
37%
654
26%
2094
15%
654
46%
654
33%
1152
March16th to endNight
33%
576
21%
2112
12%
576
47%
576
26%
1203
April1st to 15thNight
30%
539
20%
1825
12%
539
44%
539
27%
1060
April16th to endNight
34%
540
22%
1647
14%
540
46%
540
27%
1028
May1st to 15thNight
41%
540
19%
1620
14%
540
50%
540
30%
996
May16th to endNight
39%
562
18%
1685
10%
561
49%
561
29%
1032
June1st to 15thNight
44%
540
19%
1539
8%
540
52%
540
39%
879
June16th to endNight
57%
540
25%
1440
12%
540
63%
540
52%
769
July1st to 15thNight
63%
510
19%
1360
12%
510
66%
510
44%
781
July16th to endNight
70%
564
22%
1574
20%
531
73%
531
42%
854
August1st to 15thNight
67%
539
22%
1610
22%
536
71%
536
41%
889
August16th to endNight
65%
573
27%
1839
27%
573
72%
573
42%
946
September1st to 15thNight
54%
540
25%
1917
21%
540
65%
540
36%
996
September16th to endNight
55%
513
33%
1891
28%
513
66%
513
42%
870
October1st to 15thNight
47%
520
32%
1840
25%
520
57%
520
34%
944
October16th to endNight
49%
792
30%
2200
15%
792
57%
792
48%
1149
November1st to 15thNight
50%
875
35%
2275
15%
875
61%
875
54%
1179
November16th to endNight
46%
900
32%
2340
15%
900
56%
900
47%
1304
December1st to 15thNight
39%
900
24%
2340
11%
900
48%
900
38%
1408
December16th to endNight
42%
960
28%
2568
14%
960
52%
960
35%
1573

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
8%42442345%7%53%
48096
Night
7%42332345%7%54%
46963
Cloud CoverDay
8%42432345%7%53%
48094
Night
7%42332345%7%55%
46963
TransparencyDay
30%5%13%27%18%4
47783
Night
28%5%13%26%21%5%
46779
SeeingDay
11%5%28%33%17%2
5919
Night
9%7%32%38%11%
15940

By Month

Percentage Cloud Cover SW (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
5%6%1432335%6%56%
1438
16th to endDay
5%5%24423346%55%
1728
February1st to 15thDay
6%7%35%5%2445%7%46%
1696
16th to endDay
5%6%25%423447%54%
1580
March1st to 15thDay
6%5%24324446%54%
1864
16th to endDay
11%7%2342445%6%47%
2112
April1st to 15thDay
11%5%235%2335%6%50%
2120
16th to endDay
16%5%25%423347%42%
2313
May1st to 15thDay
9%5%24424447%49%
2331
16th to endDay
11%5%1332445%8%49%
2430
June1st to 15thDay
7%413314448%56%
2417
16th to endDay
2212315%45%9%61%
2520
July1st to 15thDay
5%213325%6%6%10%52%
2520
16th to endDay
5%31332346%9%55%
2484
August1st to 15thDay
7%425%5%335%6%10%45%
2340
16th to endDay
6%31342345%8%55%
2360
September1st to 15thDay
10%5%245%2325%6%51%
2041
16th to endDay
4313423347%58%
1881
October1st to 15thDay
15%313213235%56%
1779
16th to endDay
9%5%13212235%62%
1669
November1st to 15thDay
5%313323336%62%
1583
16th to endDay
7%422313336%61%
1620
December1st to 15thDay
8%7%44333446%50%
1620
16th to endDay
7%6%26%5%25%346%48%
1650
January1st to 15thNight
45%35%423346%56%
2495
16th to endNight
5%5%24313446%59%
2496
February1st to 15thNight
7%6%35%6%2445%6%46%
2168
16th to endNight
45%25%43435%6%54%
1894
March1st to 15thNight
7%6%3431435%7%52%
2094
16th to endNight
11%6%24323447%49%
2112
April1st to 15thNight
11%6%2432445%7%48%
1825
16th to endNight
15%5%2432435%7%46%
1647
May1st to 15thNight
9%5%234335%6%7%46%
1619
16th to endNight
10%413325%45%9%47%
1683
June1st to 15thNight
6%3123245%6%10%53%
1539
16th to endNight
32322346%10%60%
1440
July1st to 15thNight
42134245%6%10%52%
1440
16th to endNight
4313315%6%8%10%51%
1681
August1st to 15thNight
6%2133235%6%11%51%
1620
16th to endNight
331442345%7%59%
1839
September1st to 15thNight
7%313423449%55%
1917
16th to endNight
5%21332335%6%63%
1891
October1st to 15thNight
10%412313345%59%
1840
16th to endNight
8%312212236%64%
2200
November1st to 15thNight
5%222212246%67%
2275
16th to endNight
7%313223336%61%
2340
December1st to 15thNight
7%5%24313447%53%
2340
16th to endNight
9%6%24323446%51%
2568

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
6%5%2432335%6%56%
1438
16th to endDay
5%6%24423346%55%
1728
February1st to 15thDay
6%7%36%6%24447%46%
1696
16th to endDay
5%6%25%423447%54%
1580
March1st to 15thDay
6%5%24324446%53%
1864
16th to endDay
12%6%34414446%48%
2110
April1st to 15thDay
12%42442335%7%49%
2120
16th to endDay
17%5%35%424346%43%
2313
May1st to 15thDay
9%5%3442445%7%48%
2331
16th to endDay
12%42331345%8%48%
2430
June1st to 15thDay
7%413224348%56%
2417
16th to endDay
221232446%7%62%
2520
July1st to 15thDay
6%213325%5%7%9%52%
2520
16th to endDay
5%31332346%10%54%
2484
August1st to 15thDay
7%4244345%6%10%47%
2340
16th to endDay
7%31333246%7%56%
2360
September1st to 15thDay
10%5%2442335%5%52%
2041
16th to endDay
5%414423347%59%
1881
October1st to 15thDay
15%412212336%56%
1779
16th to endDay
9%5%1321323462%
1669
November1st to 15thDay
5%312323346%62%
1583
16th to endDay
7%5%22313236%61%
1620
December1st to 15thDay
8%7%35%334346%50%
1620
16th to endDay
8%6%36%424346%48%
1650
January1st to 15thNight
45%35%413347%56%
2495
16th to endNight
5%5%25%223345%59%
2496
February1st to 15thNight
7%6%45%6%24447%46%
2168
16th to endNight
5%5%25%42435%6%53%
1894
March1st to 15thNight
7%6%33413447%53%
2094
16th to endNight
11%6%24324347%49%
2112
April1st to 15thNight
11%6%25%32445%7%47%
1825
16th to endNight
15%5%14423448%45%
1647
May1st to 15thNight
10%5%243345%6%7%47%
1619
16th to endNight
11%41342445%9%47%
1683
June1st to 15thNight
7%2123245%6%10%53%
1539
16th to endNight
221322447%10%59%
1440
July1st to 15thNight
4213435%5%6%10%52%
1440
16th to endNight
43123246%9%9%51%
1681
August1st to 15thNight
6%2133245%6%10%51%
1620
16th to endNight
332432345%6%60%
1839
September1st to 15thNight
7%31342345%8%56%
1917
16th to endNight
5%212413347%63%
1891
October1st to 15thNight
10%412312345%59%
1840
16th to endNight
8%312312345%64%
2200
November1st to 15thNight
5%212212247%67%
2275
16th to endNight
7%312323336%62%
2340
December1st to 15thNight
7%6%2441335%7%53%
2340
16th to endNight
9%6%24323446%51%
2568

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
27%416%33%15%3
1439
16th to endDay
30%315%31%14%4
1728
February1st to 15thDay
36%6%17%25%10%3
1697
16th to endDay
30%416%22%21%5%
1580
March1st to 15thDay
30%412%27%20%5%
1864
16th to endDay
37%5%13%24%15%3
2112
April1st to 15thDay
34%5%13%27%16%2
2120
16th to endDay
41%412%25%13%1
2313
May1st to 15thDay
34%6%12%28%16%1
2331
16th to endDay
32%7%16%26%13%2
2434
June1st to 15thDay
25%6%16%29%15%5%
2417
16th to endDay
18%6%13%30%23%7%
2520
July1st to 15thDay
25%7%11%29%20%5%
2371
16th to endDay
23%5%14%32%20%3
2328
August1st to 15thDay
31%6%18%26%12%4
2326
16th to endDay
25%6%12%27%22%5%
2360
September1st to 15thDay
33%49%23%21%7%
2041
16th to endDay
26%311%30%24%3
1881
October1st to 15thDay
31%38%26%24%5%
1779
16th to endDay
26%39%29%26%5%
1669
November1st to 15thDay
24%310%26%28%5%
1583
16th to endDay
25%311%28%25%5%
1620
December1st to 15thDay
35%5%17%26%14%1
1620
16th to endDay
37%412%27%15%2
1650
January1st to 15thNight
28%313%30%21%2
2495
16th to endNight
27%314%29%21%4
2496
February1st to 15thNight
37%5%14%25%12%4
2178
16th to endNight
29%413%26%17%7%
1894
March1st to 15thNight
30%49%23%22%8%
2094
16th to endNight
35%413%23%18%3
2112
April1st to 15thNight
34%5%12%24%18%3
1825
16th to endNight
37%5%14%23%17%2
1647
May1st to 15thNight
33%7%14%20%19%3
1620
16th to endNight
33%8%16%23%15%2
1685
June1st to 15thNight
25%7%18%27%16%4
1539
16th to endNight
18%6%14%27%26%5%
1440
July1st to 15thNight
22%9%15%25%21%5%
1360
16th to endNight
23%7%17%27%18%5%
1574
August1st to 15thNight
24%7%18%30%13%5%
1610
16th to endNight
24%5%13%29%20%7%
1839
September1st to 15thNight
25%6%11%25%20%9%
1917
16th to endNight
21%410%26%30%6%
1891
October1st to 15thNight
27%5%10%23%26%7%
1840
16th to endNight
22%311%26%29%7%
2200
November1st to 15thNight
18%210%25%31%10%
2275
16th to endNight
24%310%27%25%8%
2340
December1st to 15thNight
30%5%14%30%17%1
2340
16th to endNight
33%415%24%19%2
2568

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
13%8%36%34%6%
90
16th to endDay
16%7%33%32%9%1
96
February1st to 15thDay
13%10%38%26%10%1
90
16th to endDay
118%48%16%13%2
81
March1st to 15thDay
8%13%40%31%5%1
90
16th to endDay
17%14%36%17%12%1
96
April1st to 15thDay
12%15%38%26%7%
239
16th to endDay
23%10%35%21%8%
423
May1st to 15thDay
12%8%31%30%15%1
468
16th to endDay
20%8%29%29%11%1
517
June1st to 15thDay
7%429%36%16%5%
495
16th to endDay
4229%40%22%1
495
July1st to 15thDay
7%323%37%23%4
475
16th to endDay
6%114%43%29%3
515
August1st to 15thDay
9%116%40%29%3
493
16th to endDay
9%224%38%22%3
400
September1st to 15thDay
7%329%39%17%3
196
16th to endDay
7%329%31%23%4
108
October1st to 15thDay
12%426%32%17%6%
90
16th to endDay
10%332%31%16%6%
96
November1st to 15thDay
11%320%46%12%6%
90
16th to endDay
22%10%34%23%10%
90
December1st to 15thDay
12%8%53%17%7%
90
16th to endDay
15%10%42%22%8%
96
January1st to 15thNight
8%7%38%38%6%1
900
16th to endNight
9%8%38%37%6%
960
February1st to 15thNight
11%6%40%34%7%
770
16th to endNight
8%11%38%35%5%
632
March1st to 15thNight
11%10%37%32%7%
654
16th to endNight
15%13%35%30%5%
576
April1st to 15thNight
14%12%40%28%3
539
16th to endNight
17%12%31%31%6%
540
May1st to 15thNight
11%8%33%38%8%
540
16th to endNight
12%9%34%32%9%
563
June1st to 15thNight
8%6%38%34%10%1
540
16th to endNight
3333%45%13%
540
July1st to 15thNight
4124%48%20%
510
16th to endNight
6%16%50%24%1
564
August1st to 15thNight
8%116%48%24%
539
16th to endNight
5%121%46%23%1
573
September1st to 15thNight
7%131%40%16%2
540
16th to endNight
7%5%27%39%18%1
513
October1st to 15thNight
12%7%29%36%13%
520
16th to endNight
10%6%30%37%13%
792
November1st to 15thNight
7%9%30%41%11%
875
16th to endNight
9%7%34%37%10%
900
December1st to 15thNight
11%8%36%36%6%
900
16th to endNight
13%8%31%38%8%
960
Page generated at 2017-09-23 05:43:47. Version ac04

Copyright 2017 A. Danko


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