Carranza Field
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carranza Field clear sky chart from 2005-11-06 to 2024-03-18.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	15% 6% 3 5% 5% 3 4 5% 5% 7% 41%	78612
	Night	16% 6% 3 5% 5% 3 4 4 5% 7% 43%	81152
Transparency	Day	42% 5% 12% 24% 16% 3	78318
	Night	42% 4 11% 23% 17% 3	80980
Seeing	Day	19% 14% 29% 23% 11% 4	14154
	Night	19% 11% 31% 29% 10% 1	23549

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	16% 8% 3 4 4 2 4 4 4 5% 47%	2517
	11th to 20th	Day	15% 8% 3 7% 6% 3 3 4 5% 5% 40%	2534
	21st to end	Day	23% 10% 3 6% 4 3 3 3 4 5% 36%	3124
February	1st to 10th	Day	15% 8% 3 5% 4 3 4 4 5% 7% 40%	1712
	11th to 20th	Day	18% 6% 3 5% 4 3 3 5% 5% 6% 42%	1848
	21st to end	Day	18% 8% 4 6% 5% 3 4 3 4 6% 40%	1570
March	1st to 10th	Day	15% 6% 2 5% 5% 3 4 4 4 6% 47%	1897
	11th to 20th	Day	15% 6% 2 6% 5% 3 4 4 6% 7% 42%	2015
	21st to end	Day	20% 5% 3 5% 5% 3 4 4 4 5% 40%	2330
April	1st to 10th	Day	17% 6% 2 5% 5% 3 5% 4 4 7% 42%	2160
	11th to 20th	Day	15% 4 3 4 4 2 4 4 6% 9% 43%	2134
	21st to end	Day	18% 6% 3 5% 5% 2 5% 5% 6% 8% 39%	2160
May	1st to 10th	Day	20% 7% 2 5% 5% 3 4 4 5% 7% 37%	2299
	11th to 20th	Day	19% 5% 3 5% 5% 3 4 4 6% 7% 38%	2453
	21st to end	Day	15% 6% 2 4 5% 3 4 4 6% 9% 42%	2725
June	1st to 10th	Day	13% 6% 2 6% 6% 3 5% 6% 6% 9% 39%	2520
	11th to 20th	Day	13% 5% 3 6% 5% 4 5% 5% 6% 8% 39%	2520
	21st to end	Day	10% 5% 3 6% 5% 4 6% 6% 6% 8% 41%	2520
July	1st to 10th	Day	10% 6% 3 5% 7% 4 7% 5% 6% 9% 38%	2520
	11th to 20th	Day	7% 4 3 4 6% 3 6% 7% 8% 11% 40%	2520
	21st to end	Day	10% 6% 3 6% 6% 4 7% 7% 7% 9% 35%	2738
August	1st to 10th	Day	10% 6% 3 7% 7% 3 5% 6% 7% 8% 38%	2288
	11th to 20th	Day	12% 5% 2 5% 6% 3 6% 5% 7% 9% 39%	2126
	21st to end	Day	13% 6% 3 5% 6% 3 5% 6% 7% 9% 38%	2376
September	1st to 10th	Day	14% 6% 2 4 6% 4 4 5% 6% 7% 43%	2160
	11th to 20th	Day	13% 6% 2 5% 5% 2 4 4 4 8% 49%	2104
	21st to end	Day	18% 6% 3 6% 5% 2 4 4 5% 7% 40%	1980
October	1st to 10th	Day	20% 7% 2 5% 4 2 3 4 4 6% 43%	1850
	11th to 20th	Day	17% 6% 2 4 4 2 3 4 3 7% 49%	1800
	21st to end	Day	18% 6% 3 4 4 3 4 3 3 7% 46%	1889
November	1st to 10th	Day	14% 4 2 4 5% 3 3 3 3 6% 52%	1671
	11th to 20th	Day	16% 5% 3 4 4 3 3 3 5% 6% 48%	1710
	21st to end	Day	15% 5% 2 5% 3 4 4 4 4 7% 47%	1644
December	1st to 10th	Day	20% 6% 3 5% 4 3 4 4 4 7% 40%	1520
	11th to 20th	Day	20% 7% 3 4 4 2 3 4 4 5% 45%	1906
	21st to end	Day	17% 6% 3 5% 5% 3 5% 5% 6% 8% 39%	2772
January	1st to 10th	Night	18% 6% 2 4 3 3 3 4 5% 6% 47%	4429
	11th to 20th	Night	19% 8% 3 5% 5% 2 3 3 4 5% 44%	4409
	21st to end	Night	22% 9% 3 5% 5% 3 4 4 3 5% 37%	4532
February	1st to 10th	Night	17% 8% 3 5% 4 2 4 4 5% 6% 42%	2466
	11th to 20th	Night	18% 8% 2 5% 4 3 4 4 4 6% 42%	2218
	21st to end	Night	19% 6% 2 4 5% 2 4 4 4 6% 43%	1884
March	1st to 10th	Night	16% 5% 2 6% 4 2 3 4 4 7% 46%	2270
	11th to 20th	Night	17% 7% 3 5% 4 2 4 4 4 5% 45%	2107
	21st to end	Night	18% 7% 3 5% 4 2 4 4 4 5% 43%	2026
April	1st to 10th	Night	17% 7% 3 6% 4 3 4 4 5% 6% 42%	1800
	11th to 20th	Night	14% 7% 3 6% 5% 3 4 3 4 7% 44%	1775
	21st to end	Night	19% 6% 2 4 4 3 4 4 5% 8% 42%	1800
May	1st to 10th	Night	18% 7% 3 6% 5% 4 4 4 5% 8% 35%	1661
	11th to 20th	Night	19% 7% 2 4 5% 3 4 5% 6% 7% 38%	1454
	21st to end	Night	16% 7% 4 6% 5% 3 5% 4 3 8% 39%	1550
June	1st to 10th	Night	14% 5% 2 6% 5% 2 5% 5% 5% 9% 41%	1440
	11th to 20th	Night	10% 6% 3 7% 6% 4 6% 5% 6% 8% 40%	1440
	21st to end	Night	9% 5% 3 3 5% 3 6% 5% 7% 11% 43%	1440
July	1st to 10th	Night	9% 7% 2 7% 6% 4 5% 5% 7% 9% 38%	1440
	11th to 20th	Night	7% 6% 2 4 5% 3 5% 7% 6% 10% 43%	1440
	21st to end	Night	8% 4 3 5% 6% 4 5% 5% 7% 10% 43%	1577
August	1st to 10th	Night	8% 6% 3 5% 6% 4 6% 6% 6% 9% 42%	1633
	11th to 20th	Night	10% 7% 3 6% 5% 4 4 6% 6% 9% 41%	1774
	21st to end	Night	12% 6% 2 5% 5% 3 5% 5% 6% 8% 43%	1980
September	1st to 10th	Night	14% 7% 2 5% 6% 3 4 4 4 7% 44%	1800
	11th to 20th	Night	11% 5% 2 4 4 3 3 4 4 8% 53%	1855
	21st to end	Night	18% 7% 2 5% 4 3 4 4 5% 7% 43%	1980
October	1st to 10th	Night	19% 6% 2 4 4 3 4 4 4 6% 44%	2106
	11th to 20th	Night	17% 5% 2 3 4 2 4 3 4 6% 50%	2160
	21st to end	Night	17% 6% 3 4 4 2 3 4 4 5% 47%	2466
November	1st to 10th	Night	12% 5% 2 5% 3 2 3 4 5% 6% 52%	2407
	11th to 20th	Night	16% 6% 2 5% 4 2 3 4 4 6% 47%	2470
	21st to end	Night	13% 6% 2 4 5% 3 4 5% 6% 6% 47%	2531
December	1st to 10th	Night	20% 6% 3 5% 4 2 4 4 5% 6% 40%	2660
	11th to 20th	Night	17% 5% 3 5% 5% 3 4 4 5% 7% 42%	3288
	21st to end	Night	17% 7% 3 5% 5% 3 5% 4 5% 6% 39%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	40% 3 10% 26% 17% 4	2518
	11th to 20th	Day	46% 3 10% 23% 14% 4	2534
	21st to end	Day	53% 2 9% 22% 11% 2	3124
February	1st to 10th	Day	43% 4 12% 26% 14% 2	1712
	11th to 20th	Day	43% 4 8% 25% 16% 4	1857
	21st to end	Day	48% 4 8% 21% 14% 5%	1570
March	1st to 10th	Day	41% 3 11% 27% 15% 3	1900
	11th to 20th	Day	41% 4 10% 25% 16% 4	2015
	21st to end	Day	46% 4 7% 22% 17% 4	2330
April	1st to 10th	Day	43% 4 10% 21% 17% 6%	2160
	11th to 20th	Day	38% 4 13% 24% 17% 4	2134
	21st to end	Day	42% 5% 10% 20% 18% 5%	2160
May	1st to 10th	Day	46% 4 10% 22% 15% 3	2299
	11th to 20th	Day	45% 5% 12% 23% 14% 2	2457
	21st to end	Day	39% 6% 15% 25% 13% 2	2725
June	1st to 10th	Day	41% 7% 14% 22% 15% 2	2520
	11th to 20th	Day	41% 7% 13% 24% 13% 3	2520
	21st to end	Day	39% 7% 13% 23% 17% 2	2520
July	1st to 10th	Day	41% 6% 14% 22% 14% 2	2450
	11th to 20th	Day	34% 6% 16% 28% 14% 2	2445
	21st to end	Day	41% 8% 11% 23% 14% 2	2585
August	1st to 10th	Day	40% 7% 15% 24% 14% 1	2275
	11th to 20th	Day	40% 6% 16% 21% 15% 2	2126
	21st to end	Day	39% 6% 13% 22% 16% 3	2376
September	1st to 10th	Day	39% 5% 14% 19% 20% 3	2160
	11th to 20th	Day	35% 3 8% 25% 24% 4	2104
	21st to end	Day	45% 4 8% 19% 21% 3	1980
October	1st to 10th	Day	43% 4 11% 22% 19% 2	1850
	11th to 20th	Day	36% 3 8% 26% 23% 3	1800
	21st to end	Day	41% 3 9% 24% 20% 3	1889
November	1st to 10th	Day	35% 3 11% 28% 19% 4	1671
	11th to 20th	Day	38% 3 10% 23% 24% 3	1710
	21st to end	Day	38% 3 10% 31% 14% 3	1644
December	1st to 10th	Day	44% 4 14% 23% 14% 1	1520
	11th to 20th	Day	42% 3 11% 28% 13% 3	1906
	21st to end	Day	44% 3 14% 24% 14% 1	2772
January	1st to 10th	Night	40% 2 9% 30% 14% 4	4429
	11th to 20th	Night	45% 3 9% 25% 15% 3	4409
	21st to end	Night	50% 3 7% 24% 14% 2	4532
February	1st to 10th	Night	43% 3 14% 24% 14% 2	2466
	11th to 20th	Night	44% 4 8% 20% 18% 6%	2220
	21st to end	Night	43% 2 9% 23% 17% 6%	1884
March	1st to 10th	Night	39% 3 11% 25% 18% 4	2280
	11th to 20th	Night	42% 4 9% 22% 18% 4	2108
	21st to end	Night	45% 3 8% 19% 18% 6%	2026
April	1st to 10th	Night	44% 3 9% 20% 19% 5%	1800
	11th to 20th	Night	42% 3 9% 21% 20% 4	1775
	21st to end	Night	42% 5% 9% 19% 20% 5%	1800
May	1st to 10th	Night	49% 5% 8% 20% 16% 2	1661
	11th to 20th	Night	45% 5% 12% 17% 17% 3	1455
	21st to end	Night	46% 6% 15% 18% 13% 2	1551
June	1st to 10th	Night	40% 7% 11% 22% 18% 2	1440
	11th to 20th	Night	41% 6% 13% 24% 14% 2	1440
	21st to end	Night	35% 6% 17% 25% 16% 2	1440
July	1st to 10th	Night	43% 6% 17% 20% 12% 3	1400
	11th to 20th	Night	35% 7% 16% 26% 15% 2	1392
	21st to end	Night	35% 7% 14% 28% 15% 2	1489
August	1st to 10th	Night	38% 6% 17% 23% 15% 1	1622
	11th to 20th	Night	40% 6% 16% 22% 15% 2	1774
	21st to end	Night	38% 5% 16% 20% 18% 3	1980
September	1st to 10th	Night	40% 4 13% 20% 19% 4	1800
	11th to 20th	Night	31% 4 11% 25% 25% 4	1855
	21st to end	Night	42% 5% 7% 23% 20% 3	1980
October	1st to 10th	Night	43% 4 11% 22% 18% 3	2106
	11th to 20th	Night	36% 4 11% 28% 19% 3	2160
	21st to end	Night	40% 3 9% 25% 21% 3	2466
November	1st to 10th	Night	33% 4 11% 26% 20% 6%	2407
	11th to 20th	Night	40% 4 8% 21% 21% 5%	2470
	21st to end	Night	37% 3 12% 27% 19% 2	2531
December	1st to 10th	Night	46% 3 11% 24% 15% 2	2660
	11th to 20th	Night	42% 3 12% 21% 18% 4	3288
	21st to end	Night	45% 4 13% 25% 12% 1	4884

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	22% 22% 36% 14% 4 1	180
	11th to 20th	Day	26% 32% 26% 14% 2	186
	21st to end	Day	25% 25% 29% 14% 5% 1	297
February	1st to 10th	Day	24% 25% 36% 11% 4	272
	11th to 20th	Day	27% 24% 34% 13% 2	456
	21st to end	Day	27% 23% 32% 14% 3	382
March	1st to 10th	Day	22% 25% 29% 20% 3	460
	11th to 20th	Day	20% 27% 33% 13% 5% 2	449
	21st to end	Day	25% 20% 32% 17% 6%	462
April	1st to 10th	Day	23% 24% 30% 16% 6% 1	420
	11th to 20th	Day	18% 18% 36% 18% 8% 1	412
	21st to end	Day	26% 17% 35% 14% 5% 1	420
May	1st to 10th	Day	27% 17% 32% 16% 6% 2	423
	11th to 20th	Day	22% 14% 33% 21% 7% 2	447
	21st to end	Day	20% 8% 21% 30% 18% 4	485
June	1st to 10th	Day	15% 11% 29% 28% 15% 3	450
	11th to 20th	Day	15% 10% 32% 27% 12% 4	450
	21st to end	Day	11% 7% 29% 33% 16% 4	450
July	1st to 10th	Day	13% 4 23% 30% 23% 7%	445
	11th to 20th	Day	7% 2 25% 36% 24% 7%	444
	21st to end	Day	11% 5% 27% 34% 17% 6%	488
August	1st to 10th	Day	10% 4 27% 31% 21% 7%	446
	11th to 20th	Day	14% 1 23% 33% 22% 7%	439
	21st to end	Day	13% 6% 23% 29% 19% 10%	495
September	1st to 10th	Day	18% 7% 25% 23% 17% 10%	450
	11th to 20th	Day	15% 6% 23% 30% 16% 10%	450
	21st to end	Day	22% 10% 27% 25% 11% 5%	450
October	1st to 10th	Day	25% 7% 25% 25% 13% 6%	450
	11th to 20th	Day	18% 15% 26% 25% 14% 2	450
	21st to end	Day	20% 14% 33% 20% 12% 1	449
November	1st to 10th	Day	17% 11% 34% 24% 12% 3	365
	11th to 20th	Day	19% 21% 31% 22% 7%	370
	21st to end	Day	17% 17% 34% 22% 8% 2	304
December	1st to 10th	Day	25% 22% 37% 10% 6% 1	180
	11th to 20th	Day	29% 18% 34% 15% 3 1	180
	21st to end	Day	26% 16% 31% 19% 7% 2	198
January	1st to 10th	Night	20% 18% 37% 21% 3 1	760
	11th to 20th	Night	23% 18% 33% 23% 4	760
	21st to end	Night	19% 16% 39% 24% 2	836
February	1st to 10th	Night	21% 16% 38% 23% 2	760
	11th to 20th	Night	24% 22% 38% 15% 1	743
	21st to end	Night	23% 20% 33% 20% 3	628
March	1st to 10th	Night	21% 17% 36% 22% 4	760
	11th to 20th	Night	22% 17% 34% 21% 5% 1	752
	21st to end	Night	22% 11% 41% 20% 6%	792
April	1st to 10th	Night	21% 19% 36% 18% 5%	720
	11th to 20th	Night	17% 13% 39% 26% 5%	711
	21st to end	Night	21% 11% 36% 27% 4	720
May	1st to 10th	Night	21% 10% 37% 24% 7%	581
	11th to 20th	Night	22% 9% 35% 28% 5%	393
	21st to end	Night	21% 2 21% 41% 13% 2	389
June	1st to 10th	Night	18% 4 27% 39% 12% 1	360
	11th to 20th	Night	12% 3 28% 42% 15%	360
	21st to end	Night	10% 2 28% 46% 14%	360
July	1st to 10th	Night	12% 2 21% 46% 17% 2	350
	11th to 20th	Night	9% 3 17% 49% 20% 2	348
	21st to end	Night	9% 3 22% 48% 17% 1	397
August	1st to 10th	Night	10% 1 18% 46% 23% 2	559
	11th to 20th	Night	12% 4 18% 41% 24% 2	710
	21st to end	Night	13% 1 18% 41% 23% 3	792
September	1st to 10th	Night	18% 3 21% 38% 18% 3	720
	11th to 20th	Night	13% 3 20% 37% 22% 4	720
	21st to end	Night	23% 4 23% 32% 17% 1	720
October	1st to 10th	Night	21% 6% 25% 28% 16% 3	720
	11th to 20th	Night	19% 9% 26% 33% 13% 1	720
	21st to end	Night	20% 10% 35% 26% 9% 1	792
November	1st to 10th	Night	16% 9% 34% 29% 12% 1	740
	11th to 20th	Night	19% 13% 31% 28% 8% 1	760
	21st to end	Night	16% 14% 35% 26% 8% 1	760
December	1st to 10th	Night	24% 14% 34% 21% 7% 1	760
	11th to 20th	Night	19% 14% 37% 24% 6%	760
	21st to end	Night	21% 12% 37% 27% 2	836

Page generated at 2024-03-15 14:01:44. Version ac07

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