Baltimore Bend
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Baltimore Bend 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
43%
16202
22%
47862
14%
16155
50%
16155
30%
29445

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
31%
900
21%
2351
8%
895
41%
895
31%
1506
January16th to endNight
28%
960
22%
2496
8%
960
37%
960
29%
1652
February1st to 15thNight
25%
880
14%
2288
5%
876
30%
876
21%
1644
February16th to endNight
28%
681
22%
1943
7%
681
40%
681
28%
1227
March1st to 15thNight
35%
540
21%
1980
13%
540
44%
540
23%
1204
March16th to endNight
28%
576
14%
2112
9%
576
36%
576
16%
1438
April1st to 15thNight
35%
539
21%
1815
14%
539
48%
539
28%
1062
April16th to endNight
37%
540
21%
1763
16%
540
49%
540
23%
1140
May1st to 15thNight
43%
539
18%
1619
15%
539
49%
539
26%
1056
May16th to endNight
46%
563
20%
1549
13%
561
51%
561
30%
1013
June1st to 15thNight
61%
540
21%
1440
12%
540
65%
540
42%
838
June16th to endNight
62%
540
23%
1440
13%
540
67%
540
47%
812
July1st to 15thNight
70%
510
19%
1426
15%
510
71%
510
41%
828
July16th to endNight
76%
564
24%
1594
24%
531
79%
531
45%
837
August1st to 15thNight
76%
539
24%
1610
29%
536
78%
536
44%
857
August16th to endNight
74%
573
25%
1850
31%
573
76%
573
38%
996
September1st to 15thNight
66%
540
26%
1800
27%
540
69%
540
34%
1008
September16th to endNight
62%
567
28%
1997
24%
567
70%
567
34%
1058
October1st to 15thNight
46%
720
27%
2160
19%
720
51%
720
34%
1250
October16th to endNight
39%
768
29%
2304
16%
768
49%
768
34%
1318
November1st to 15thNight
40%
778
26%
2360
15%
778
51%
778
32%
1374
November16th to endNight
32%
975
24%
2730
10%
975
43%
975
30%
1713
December1st to 15thNight
30%
910
16%
2547
7%
910
37%
910
24%
1733
December16th to endNight
27%
960
19%
2688
6%
960
37%
960
21%
1881

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
12%6%35%42445%7%43%
48577
Night
12%5%24423446%48%
48053
TransparencyDay
40%6%13%24%13%1
48273
Night
36%5%12%25%17%2
47863
SeeingDay
13%5%24%29%21%5%
6150
Night
14%7%30%32%13%1
16203

By Month

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
12%6%46%5%33436%41%
1584
16th to endDay
15%8%47%5%34435%37%
1728
February1st to 15thDay
14%9%47%6%23347%35%
1575
16th to endDay
12%8%46%5%23346%39%
1537
March1st to 15thDay
12%10%46%6%34447%36%
1980
16th to endDay
21%9%46%5%24445%30%
2110
April1st to 15thDay
16%7%34425%345%41%
2133
16th to endDay
22%7%35%434447%32%
2196
May1st to 15thDay
17%7%36%5%35%445%35%
2331
16th to endDay
13%5%26%5%35%45%9%37%
2563
June1st to 15thDay
8%5%25%5%345%6%8%43%
2520
16th to endDay
6%3244345%6%10%47%
2520
July1st to 15thDay
8%423435%5%6%9%45%
2445
16th to endDay
6%3144345%6%9%49%
2466
August1st to 15thDay
7%4245%3446%8%48%
2340
16th to endDay
8%4244345%6%7%48%
2351
September1st to 15thDay
11%423423447%50%
2160
16th to endDay
9%42341445%8%51%
1949
October1st to 15thDay
15%423423346%50%
1800
16th to endDay
13%5%2432325%5%51%
1920
November1st to 15thDay
12%6%24313445%51%
1823
16th to endDay
17%7%33311235%47%
1560
December1st to 15thDay
14%10%5%7%423346%37%
1450
16th to endDay
14%9%5%7%433345%37%
1536
January1st to 15thNight
10%6%25%5%34345%47%
2351
16th to endNight
9%8%36%424446%44%
2496
February1st to 15thNight
13%8%46%5%345%45%37%
2278
16th to endNight
13%7%25%31335%6%47%
1943
March1st to 15thNight
15%6%25%324346%44%
1980
16th to endNight
20%6%35%5%3435%7%34%
2112
April1st to 15thNight
12%6%24323335%50%
1815
16th to endNight
19%5%25%333435%43%
1763
May1st to 15thNight
14%426%5%235%5%7%42%
1619
16th to endNight
13%325%42445%9%44%
1547
June1st to 15thNight
6%31342435%12%52%
1440
16th to endNight
42133245%6%8%56%
1440
July1st to 15thNight
8%3135%3345%9%52%
1511
16th to endNight
41133245%6%11%53%
1702
August1st to 15thNight
421432446%9%56%
1620
16th to endNight
7%312425%347%56%
1850
September1st to 15thNight
10%41431445%7%52%
1800
16th to endNight
7%41332445%7%54%
1997
October1st to 15thNight
14%413312335%54%
2160
16th to endNight
12%414312335%56%
2304
November1st to 15thNight
12%5%23323336%54%
2360
16th to endNight
15%6%23314345%49%
2730
December1st to 15thNight
16%7%35%424345%40%
2547
16th to endNight
18%9%47%413335%38%
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
44%5%11%22%15%1
1585
16th to endDay
48%416%20%8%1
1728
February1st to 15thDay
48%6%14%21%7%1
1576
16th to endDay
45%414%20%13%1
1537
March1st to 15thDay
48%6%11%23%8%1
1980
16th to endDay
55%6%11%18%6%
2112
April1st to 15thDay
44%6%11%24%12%
2133
16th to endDay
51%5%12%19%10%
2196
May1st to 15thDay
49%6%11%22%8%
2331
16th to endDay
42%8%14%21%10%1
2567
June1st to 15thDay
35%8%13%27%13%1
2520
16th to endDay
29%8%17%28%14%2
2520
July1st to 15thDay
32%8%16%26%12%3
2302
16th to endDay
28%8%15%31%15%
2311
August1st to 15thDay
32%7%15%27%15%1
2326
16th to endDay
32%7%12%23%18%5%
2351
September1st to 15thDay
33%5%11%24%19%5%
2160
16th to endDay
30%7%12%30%17%2
1949
October1st to 15thDay
35%410%25%20%4
1800
16th to endDay
35%410%25%20%4
1920
November1st to 15thDay
34%413%23%19%3
1823
16th to endDay
40%210%29%15%
1560
December1st to 15thDay
49%414%21%9%
1450
16th to endDay
49%413%20%9%1
1536
January1st to 15thNight
37%5%13%26%16%
2351
16th to endNight
39%5%15%24%14%1
2496
February1st to 15thNight
48%6%10%20%12%1
2288
16th to endNight
38%5%13%22%18%1
1943
March1st to 15thNight
40%5%10%24%15%2
1980
16th to endNight
49%5%12%21%9%1
2112
April1st to 15thNight
35%49%27%19%3
1815
16th to endNight
42%5%9%23%16%1
1763
May1st to 15thNight
40%7%14%21%14%1
1620
16th to endNight
38%7%13%24%14%1
1549
June1st to 15thNight
26%6%15%30%18%2
1440
16th to endNight
22%6%14%31%19%4
1440
July1st to 15thNight
28%5%11%34%17%2
1426
16th to endNight
22%6%15%36%17%1
1594
August1st to 15thNight
22%6%16%30%21%2
1610
16th to endNight
26%6%9%25%25%6%
1850
September1st to 15thNight
29%6%10%22%23%6%
1800
16th to endNight
28%5%11%30%20%2
1997
October1st to 15thNight
32%48%25%21%6%
2160
16th to endNight
32%39%26%23%5%
2304
November1st to 15thNight
32%411%22%21%6%
2360
16th to endNight
37%49%28%18%2
2730
December1st to 15thNight
45%415%22%12%
2547
16th to endNight
49%411%20%11%2
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
25%12%34%21%6%
90
16th to endDay
22%14%34%19%7%1
96
February1st to 15thDay
11%24%37%21%5%
90
16th to endDay
13%18%40%14%12%
81
March1st to 15thDay
21%17%43%13%4
90
16th to endDay
29%15%33%18%3
96
April1st to 15thDay
19%13%29%26%9%1
252
16th to endDay
25%8%28%25%11%1
306
May1st to 15thDay
17%8%34%26%11%1
468
16th to endDay
16%5%28%29%16%4
517
June1st to 15thDay
9%323%34%23%6%
495
16th to endDay
6%330%33%21%4
495
July1st to 15thDay
11%116%33%29%8%
475
16th to endDay
5%11%32%41%9%
515
August1st to 15thDay
7%110%35%35%9%
493
16th to endDay
8%113%32%32%9%
391
September1st to 15thDay
10%14%34%33%6%
315
16th to endDay
5%322%35%26%6%
146
October1st to 15thDay
11%6%34%28%14%4
135
16th to endDay
12%11%39%27%9%
144
November1st to 15thDay
18%5%25%28%14%8%
135
16th to endDay
31%13%25%20%8%
135
December1st to 15thDay
22%15%31%19%5%5%
94
16th to endDay
22%17%38%18%2
96
January1st to 15thNight
13%11%38%27%8%
900
16th to endNight
13%10%42%29%4
960
February1st to 15thNight
15%10%42%28%3
880
16th to endNight
17%10%40%26%4
681
March1st to 15thNight
18%9%34%31%5%
540
16th to endNight
23%9%35%24%7%
576
April1st to 15thNight
15%11%35%30%7%
539
16th to endNight
20%6%31%31%9%
540
May1st to 15thNight
16%6%27%37%10%1
540
16th to endNight
14%429%31%17%2
563
June1st to 15thNight
7%122%46%19%2
540
16th to endNight
4125%45%20%2
540
July1st to 15thNight
9%111%47%27%2
510
16th to endNight
5%10%40%41%1
564
August1st to 15thNight
48%43%40%2
539
16th to endNight
7%12%41%33%4
573
September1st to 15thNight
12%114%38%28%4
540
16th to endNight
9%220%35%26%5%
567
October1st to 15thNight
17%428%30%16%2
720
16th to endNight
15%7%34%30%11%
768
November1st to 15thNight
14%10%31%32%11%
778
16th to endNight
17%10%37%26%6%
975
December1st to 15thNight
19%9%36%27%5%
910
16th to endNight
22%8%34%28%4
960
Page generated at 2017-12-03 10:16:36. Version ac04

Copyright 2017 A. Danko


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