Bentsen-Rio Grande Valley State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bentsen-Rio Grande Valley State Park clear sky chart from 2005-11-05 to 2017-09-20.

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
0%
5818000
85%
15101

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
0%
453000
73%
889
January16th to endNight
0%
366000
80%
768
February1st to 15thNight
0%
394000
80%
700
February16th to endNight
0%
404000
80%
629
March1st to 15thNight
0%
316000
79%
540
March16th to endNight
0%
376000
84%
576
April1st to 15thNight
0%
334000
86%
539
April16th to endNight
0%
326000
82%
540
May1st to 15thNight
0%
344000
85%
540
May16th to endNight
0%
251000
90%
561
June1st to 15thNight
0%
82000
97%
540
June16th to endNight
0%
100000
93%
540
July1st to 15thNight
0%
95000
91%
510
July16th to endNight
0%
49000
95%
531
August1st to 15thNight
0%
24000
99%
536
August16th to endNight
0%
64000
93%
573
September1st to 15thNight
0%
76000
89%
540
September16th to endNight
0%
79000
88%
507
October1st to 15thNight
0%
69000
95%
495
October16th to endNight
0%
174000
90%
665
November1st to 15thNight
0%
235000
86%
700
November16th to endNight
0%
307000
85%
822
December1st to 15thNight
0%
411000
78%
900
December16th to endNight
0%
489000
72%
960

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
TransparencyDay
100%
47473
Night
100%
47055
SeeingDay
9%218%38%23%8%
5035
Night
11%224%40%19%1
15148

By Month

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
100%
1627
16th to endDay
100%
1920
February1st to 15thDay
100%
1751
16th to endDay
100%
1580
March1st to 15thDay
100%
1980
16th to endDay
100%
2112
April1st to 15thDay
100%
1971
16th to endDay
100%
2033
May1st to 15thDay
100%
2331
16th to endDay
100%
2434
June1st to 15thDay
100%
2340
16th to endDay
100%
2340
July1st to 15thDay
100%
2201
16th to endDay
100%
2271
August1st to 15thDay
100%
2147
16th to endDay
100%
2193
September1st to 15thDay
100%
1980
16th to endDay
100%
1859
October1st to 15thDay
100%
1815
16th to endDay
100%
1787
November1st to 15thDay
100%
1758
16th to endDay
100%
1695
December1st to 15thDay
100%
1620
16th to endDay
100%
1728
January1st to 15thNight
100%
2321
16th to endNight
100%
2304
February1st to 15thNight
100%
2112
16th to endNight
100%
1891
March1st to 15thNight
100%
1980
16th to endNight
100%
2112
April1st to 15thNight
100%
1977
16th to endNight
100%
1920
May1st to 15thNight
100%
1620
16th to endNight
100%
1685
June1st to 15thNight
100%
1620
16th to endNight
100%
1620
July1st to 15thNight
100%
1530
16th to endNight
100%
1630
August1st to 15thNight
100%
1789
16th to endNight
100%
2008
September1st to 15thNight
100%
1980
16th to endNight
100%
1870
October1st to 15thNight
100%
1815
16th to endNight
100%
2073
November1st to 15thNight
100%
2100
16th to endNight
100%
2262
December1st to 15thNight
100%
2340
16th to endNight
100%
2496

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%325%31%11%3
90
16th to endDay
12%436%32%11%3
96
February1st to 15thDay
4238%27%23%3
90
16th to endDay
11%339%33%11%1
81
March1st to 15thDay
27%5%20%33%13%
90
16th to endDay
10%437%41%6%
96
April1st to 15thDay
7%336%36%14%1
90
16th to endDay
9%9%26%38%13%2
143
May1st to 15thDay
12%444%31%7%
468
16th to endDay
6%338%37%11%1
517
June1st to 15thDay
210%47%31%6%
495
16th to endDay
7%110%44%27%10%
495
July1st to 15thDay
8%10%41%32%5%
475
16th to endDay
4343%40%8%
472
August1st to 15thDay
1255%27%11%
315
16th to endDay
6%7%42%23%19%
233
September1st to 15thDay
11%1325%42%16%
135
16th to endDay
6%14%39%38%
102
October1st to 15thDay
5%1214%36%40%
90
16th to endDay
16%16%28%34%13%
96
November1st to 15thDay
30%5%13%31%16%3
90
16th to endDay
22%5%21%26%13%11%
90
December1st to 15thDay
27%123%14%22%11%
90
16th to endDay
25%6%25%28%9%6%
96
January1st to 15thNight
22%324%35%13%
894
16th to endNight
15%328%42%8%
768
February1st to 15thNight
15%435%35%7%
704
16th to endNight
15%345%29%6%
629
March1st to 15thNight
15%5%37%35%5%
540
16th to endNight
10%5%49%30%3
576
April1st to 15thNight
9%448%33%4
539
16th to endNight
12%443%35%4
540
May1st to 15thNight
9%5%49%32%3
540
16th to endNight
5%335%46%8%
563
June1st to 15thNight
212%59%24%
540
16th to endNight
5%112%54%25%2
540
July1st to 15thNight
7%10%54%26%
510
16th to endNight
3455%33%2
564
August1st to 15thNight
352%40%2
539
16th to endNight
6%439%43%5%
573
September1st to 15thNight
10%331%47%7%
540
16th to endNight
10%431%44%8%
507
October1st to 15thNight
49%40%41%4
495
16th to endNight
7%216%42%29%1
665
November1st to 15thNight
11%219%41%23%1
700
16th to endNight
12%222%39%20%2
822
December1st to 15thNight
18%324%36%16%1
900
16th to endNight
22%5%23%33%15%
960
Page generated at 2017-09-21 06:18:12. Version ac04

Copyright 2017 A. Danko


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