Getchell Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Getchell Mountain 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
23%
14815
15%
46855
6%
14780
33%
14780
16%
32530

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
16%
729
16%
2562
3%
725
31%
725
12%
1745
January16th to endNight
14%
768
15%
2658
2%
768
30%
768
12%
1842
February1st to 15thNight
14%
704
12%
2286
3%
701
25%
701
13%
1650
February16th to endNight
15%
631
14%
1921
3%
631
28%
631
13%
1403
March1st to 15thNight
16%
720
16%
2076
5%
720
28%
720
14%
1508
March16th to endNight
22%
768
18%
2112
6%
768
31%
768
19%
1490
April1st to 15thNight
17%
647
15%
1758
3%
647
26%
647
16%
1286
April16th to endNight
20%
540
15%
1620
5%
540
28%
540
16%
1146
May1st to 15thNight
21%
540
12%
1620
5%
540
30%
540
14%
1205
May16th to endNight
21%
462
11%
1452
5%
461
30%
461
13%
1096
June1st to 15thNight
23%
360
9%
1260
6%
360
29%
360
13%
939
June16th to endNight
32%
360
8%
1260
7%
360
36%
360
17%
869
July1st to 15thNight
36%
340
10%
1224
9%
340
43%
340
20%
798
July16th to endNight
39%
397
10%
1438
10%
374
45%
374
17%
965
August1st to 15thNight
40%
539
10%
1608
7%
535
44%
535
22%
1098
August16th to endNight
41%
573
21%
1719
12%
573
46%
573
28%
1059
September1st to 15thNight
33%
684
15%
1899
7%
684
40%
684
29%
1224
September16th to endNight
36%
685
26%
1891
13%
685
47%
685
33%
1134
October1st to 15thNight
28%
660
20%
1922
9%
660
38%
660
22%
1280
October16th to endNight
20%
704
15%
2225
4%
704
33%
704
16%
1552
November1st to 15thNight
23%
704
18%
2301
7%
704
37%
704
17%
1551
November16th to endNight
23%
750
17%
2520
6%
750
36%
750
14%
1721
December1st to 15thNight
14%
750
13%
2643
4%
750
26%
750
11%
1903
December16th to endNight
11%
800
14%
2880
3%
800
25%
800
9%
2066

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
19%8%36%5%34446%33%
48035
Night
18%8%36%5%34446%34%
47022
TransparencyDay
49%6%11%20%11%1
47720
Night
48%6%11%21%11%1
46855
SeeingDay
25%14%31%19%7%1
6594
Night
24%14%33%21%5%
14815

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
15%10%46%5%35%446%32%
1376
16th to endDay
16%10%36%6%24446%33%
1564
February1st to 15thDay
13%12%48%6%35%45%6%28%
1575
16th to endDay
14%12%48%7%25%446%28%
1551
March1st to 15thDay
21%11%35%425%345%31%
1873
16th to endDay
16%10%47%5%24346%34%
2112
April1st to 15thDay
20%11%36%5%23346%31%
2188
16th to endDay
23%8%35%423345%34%
2340
May1st to 15thDay
24%8%35%5%33446%29%
2332
16th to endDay
23%7%35%5%25%35%6%29%
2670
June1st to 15thDay
27%8%46%5%24446%26%
2700
16th to endDay
23%7%36%5%25%5%6%6%27%
2700
July1st to 15thDay
14%5%26%5%36%5%6%9%34%
2661
16th to endDay
16%7%36%6%45%46%8%31%
2621
August1st to 15thDay
16%7%26%6%35%46%7%33%
2340
16th to endDay
13%5%26%6%35%45%7%41%
2483
September1st to 15thDay
14%6%35%433336%45%
2058
16th to endDay
16%6%23323336%48%
1881
October1st to 15thDay
20%7%25%5%23246%38%
1708
16th to endDay
22%9%35%42335%5%33%
1645
November1st to 15thDay
22%7%25%324437%35%
1557
16th to endDay
21%9%25%5%13446%35%
1440
December1st to 15thDay
24%9%35%5%245%35%29%
1316
16th to endDay
22%13%46%5%3424427%
1344
January1st to 15thNight
15%9%36%5%2445%6%33%
2562
16th to endNight
13%9%46%6%36%5%5%6%31%
2658
February1st to 15thNight
13%10%37%7%46%5%6%7%27%
2285
16th to endNight
16%12%47%5%35%435%31%
1921
March1st to 15thNight
19%11%45%434345%32%
2064
16th to endNight
17%8%36%5%24345%36%
2112
April1st to 15thNight
20%9%46%5%24446%31%
1758
16th to endNight
23%7%345%34346%33%
1620
May1st to 15thNight
22%7%36%5%3446%5%28%
1620
16th to endNight
21%9%47%6%34445%28%
1450
June1st to 15thNight
24%8%37%5%34447%25%
1260
16th to endNight
20%6%26%6%3345%9%31%
1260
July1st to 15thNight
14%5%36%5%246%6%9%35%
1297
16th to endNight
18%6%26%43446%7%33%
1535
August1st to 15thNight
16%6%25%5%35%5%5%7%37%
1620
16th to endNight
12%5%15%33345%7%47%
1719
September1st to 15thNight
16%6%24324447%44%
1899
16th to endNight
13%413313347%52%
1891
October1st to 15thNight
19%6%15%42345%5%40%
1922
16th to endNight
22%7%35%5%23345%35%
2225
November1st to 15thNight
20%6%25%5%33436%37%
2301
16th to endNight
19%8%25%5%23446%35%
2520
December1st to 15thNight
24%8%35%5%34435%30%
2643
16th to endNight
24%9%35%6%33346%29%
2880

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
49%5%14%18%10%1
1377
16th to endDay
49%5%10%22%10%
1564
February1st to 15thDay
54%6%10%18%8%1
1578
16th to endDay
54%5%10%17%9%1
1551
March1st to 15thDay
53%410%16%12%1
1884
16th to endDay
49%410%18%13%2
2112
April1st to 15thDay
53%47%17%14%1
2188
16th to endDay
51%5%8%17%13%4
2340
May1st to 15thDay
54%5%8%18%10%2
2332
16th to endDay
52%7%11%20%7%
2674
June1st to 15thDay
57%6%10%15%8%1
2700
16th to endDay
53%7%10%16%10%
2700
July1st to 15thDay
43%8%13%21%11%
2505
16th to endDay
48%8%13%20%9%
2456
August1st to 15thDay
46%8%12%23%8%
2327
16th to endDay
39%7%13%25%13%
2483
September1st to 15thDay
38%5%10%27%15%1
2058
16th to endDay
36%48%30%19%1
1881
October1st to 15thDay
45%5%10%26%12%
1708
16th to endDay
51%6%11%22%8%
1645
November1st to 15thDay
48%6%14%16%13%
1557
16th to endDay
49%5%14%19%10%
1440
December1st to 15thDay
55%6%11%19%6%
1316
16th to endDay
58%5%8%17%9%
1344
January1st to 15thNight
48%6%11%21%10%1
2562
16th to endNight
49%7%10%22%9%
2658
February1st to 15thNight
53%6%12%18%8%
2286
16th to endNight
54%48%17%12%1
1921
March1st to 15thNight
53%48%19%12%1
2076
16th to endNight
47%5%9%21%14%1
2112
April1st to 15thNight
52%6%8%14%15%3
1758
16th to endNight
51%5%9%15%14%4
1620
May1st to 15thNight
54%6%8%15%12%1
1620
16th to endNight
55%8%9%17%8%
1452
June1st to 15thNight
57%6%11%18%5%1
1260
16th to endNight
49%6%13%19%10%
1260
July1st to 15thNight
43%8%15%21%11%
1224
16th to endNight
47%8%13%21%9%
1438
August1st to 15thNight
44%8%16%21%9%
1608
16th to endNight
35%7%14%29%12%
1719
September1st to 15thNight
38%5%12%27%14%
1899
16th to endNight
32%411%32%17%
1891
October1st to 15thNight
44%410%24%14%
1922
16th to endNight
48%6%11%22%10%
2225
November1st to 15thNight
46%6%13%21%11%
2301
16th to endNight
49%5%12%20%11%
2520
December1st to 15thNight
54%5%11%21%7%
2643
16th to endNight
55%5%10%18%9%
2880

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
36%6%41%13%1
60
16th to endDay
23%16%35%19%4
92
February1st to 15thDay
19%21%39%16%2
236
16th to endDay
22%18%34%19%4
234
March1st to 15thDay
31%20%32%12%3
270
16th to endDay
26%19%31%14%5%2
288
April1st to 15thDay
32%18%27%15%32
270
16th to endDay
31%18%30%14%41
270
May1st to 15thDay
34%16%29%14%31
288
16th to endDay
28%16%31%17%6%
462
June1st to 15thDay
32%12%28%20%6%
495
16th to endDay
28%8%32%20%8%1
495
July1st to 15thDay
20%9%32%23%11%2
439
16th to endDay
19%5%32%30%10%
326
August1st to 15thDay
18%8%30%30%10%1
313
16th to endDay
16%10%29%26%13%3
332
September1st to 15thDay
19%11%34%20%11%3
315
16th to endDay
16%12%34%15%15%6%
278
October1st to 15thDay
26%14%24%16%13%4
236
16th to endDay
31%17%28%16%41
240
November1st to 15thDay
26%16%29%18%6%2
235
16th to endDay
27%22%24%18%6%
240
December1st to 15thDay
32%21%28%12%5%
116
16th to endDay
42%20%32%4
64
January1st to 15thNight
24%18%33%20%2
729
16th to endNight
23%19%36%17%2
768
February1st to 15thNight
21%17%40%17%2
704
16th to endNight
25%20%33%17%2
631
March1st to 15thNight
27%17%35%17%2
720
16th to endNight
23%15%34%20%5%
768
April1st to 15thNight
27%17%33%16%4
647
16th to endNight
29%14%33%16%5%
540
May1st to 15thNight
27%13%31%22%4
540
16th to endNight
24%11%36%22%5%
462
June1st to 15thNight
27%6%36%23%6%
360
16th to endNight
23%5%33%30%7%
360
July1st to 15thNight
17%339%30%8%
340
16th to endNight
19%231%36%9%
397
August1st to 15thNight
19%5%27%35%12%
539
16th to endNight
15%5%31%33%12%1
573
September1st to 15thNight
20%8%33%28%9%
684
16th to endNight
17%9%33%26%12%1
685
October1st to 15thNight
22%11%31%22%9%1
660
16th to endNight
26%16%33%18%4
704
November1st to 15thNight
24%15%30%21%7%
704
16th to endNight
24%18%29%19%7%
750
December1st to 15thNight
31%16%31%16%3
750
16th to endNight
32%20%30%13%2
800
Page generated at 2017-09-23 06:43:42. Version ac04

Copyright 2017 A. Danko


Getchell Mountain Clear Sky Chart | Charts Home