Tulelake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tulelake clear sky chart from 2005-11-06 to 2024-11-02.

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 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	7% 7% 2 5% 4 3 3 3 4 6% 55%	101459
	Night	8% 8% 2 5% 4 4 4 3 5% 6% 52%	97707
Transparency	Day	29% 6% 9% 19% 21% 16%	101205
	Night	32% 7% 11% 21% 18% 11%	97550
Seeing	Day	11% 10% 20% 25% 22% 12%	14877
	Night	10% 6% 18% 38% 24% 3	23987

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	12% 17% 6% 9% 7% 6% 5% 4 5% 6% 24%	2539
	11th to 20th	Day	21% 21% 5% 8% 4 3 4 3 4 6% 22%	2576
	21st to end	Day	20% 13% 3 8% 4 4 4 3 4 7% 30%	3146
February	1st to 10th	Day	9% 10% 3 7% 5% 6% 5% 4 6% 8% 37%	1710
	11th to 20th	Day	9% 11% 4 7% 6% 6% 5% 4 5% 8% 37%	1703
	21st to end	Day	7% 13% 4 8% 6% 6% 6% 4 4 7% 34%	1570
March	1st to 10th	Day	10% 20% 5% 9% 5% 5% 4 4 5% 6% 28%	3224
	11th to 20th	Day	7% 9% 2 4 4 3 3 3 3 6% 55%	3490
	21st to end	Day	10% 15% 4 10% 6% 6% 5% 4 5% 7% 29%	3969
April	1st to 10th	Day	9% 10% 3 10% 6% 6% 6% 4 5% 5% 37%	2280
	11th to 20th	Day	12% 9% 3 6% 4 4 3 3 6% 7% 43%	2249
	21st to end	Day	7% 6% 2 7% 4 4 3 4 5% 9% 49%	2280
May	1st to 10th	Day	7% 7% 2 6% 3 3 3 3 4 6% 56%	4281
	11th to 20th	Day	5% 4 1 4 3 3 2 2 4 5% 68%	4377
	21st to end	Day	6% 5% 1 4 3 3 3 4 5% 7% 59%	4813
June	1st to 10th	Day	8% 5% 2 5% 4 4 5% 5% 7% 7% 49%	2660
	11th to 20th	Day	3 3 1 3 3 3 3 3 4 7% 66%	2660
	21st to end	Day	4 2 1 2 2 2 3 2 4 5% 74%	2660
July	1st to 10th	Day	1 1 1 1 1 1 2 2 3 86%	4420
	11th to 20th	Day	2 2 1 3 3 2 3 2 4 4 76%	4420
	21st to end	Day	1 1 1 1 1 2 2 2 4 3 82%	4706
August	1st to 10th	Day	3 2 1 3 2 2 3 3 5% 5% 70%	4091
	11th to 20th	Day	1 1 1 1 2 2 2 3 6% 79%	3937
	21st to end	Day	2 1 1 2 1 2 2 2 3 5% 80%	4180
September	1st to 10th	Day	1 1 2 2 2 2 2 4 4 81%	2280
	11th to 20th	Day	4 2 1 3 3 3 3 3 4 6% 68%	2280
	21st to end	Day	4 3 1 4 3 2 3 2 4 7% 67%	2033
October	1st to 10th	Day	7% 4 1 5% 3 2 3 3 3 6% 64%	1900
	11th to 20th	Day	8% 4 1 3 3 3 3 3 6% 8% 57%	1900
	21st to end	Day	9% 6% 1 6% 4 4 4 4 6% 7% 50%	2065
November	1st to 10th	Day	13% 9% 3 6% 4 5% 4 3 5% 8% 40%	1683
	11th to 20th	Day	12% 8% 3 7% 6% 4 5% 5% 8% 9% 33%	1615
	21st to end	Day	8% 10% 3 9% 5% 5% 5% 4 5% 8% 38%	1520
December	1st to 10th	Day	10% 11% 3 7% 4 5% 5% 4 6% 8% 37%	1520
	11th to 20th	Day	19% 11% 4 8% 6% 4 5% 4 7% 9% 23%	1928
	21st to end	Day	13% 12% 5% 12% 7% 6% 6% 4 6% 7% 23%	2794
January	1st to 10th	Night	10% 12% 5% 9% 7% 7% 6% 5% 6% 8% 25%	4406
	11th to 20th	Night	17% 17% 3 8% 5% 5% 5% 3 5% 6% 27%	4384
	21st to end	Night	19% 13% 4 8% 5% 5% 4 4 4 6% 28%	4521
February	1st to 10th	Night	9% 10% 3 6% 5% 6% 5% 4 5% 8% 41%	2470
	11th to 20th	Night	10% 11% 3 6% 4 4 4 4 5% 6% 42%	2364
	21st to end	Night	8% 9% 3 7% 5% 5% 5% 4 6% 7% 40%	1884
March	1st to 10th	Night	10% 18% 4 8% 5% 4 5% 4 5% 6% 31%	3648
	11th to 20th	Night	9% 9% 2 4 3 3 3 3 4 7% 52%	3490
	21st to end	Night	9% 12% 3 8% 6% 6% 6% 4 6% 8% 31%	3684
April	1st to 10th	Night	10% 10% 3 6% 5% 5% 4 3 6% 7% 41%	1900
	11th to 20th	Night	8% 10% 2 6% 4 4 3 3 4 6% 48%	1879
	21st to end	Night	9% 6% 2 6% 3 3 3 3 5% 8% 52%	1900
May	1st to 10th	Night	7% 5% 2 4 4 4 3 3 4 4 59%	2679
	11th to 20th	Night	5% 3 1 3 2 2 3 2 5% 5% 69%	2516
	21st to end	Night	5% 4 1 3 2 3 3 2 4 6% 68%	2762
June	1st to 10th	Night	9% 6% 2 5% 3 4 4 3 5% 8% 52%	1520
	11th to 20th	Night	5% 3 1 3 2 3 3 2 4 5% 69%	1520
	21st to end	Night	3 3 1 2 3 2 2 2 3 4 76%	1520
July	1st to 10th	Night	1 2 1 1 1 2 2 3 87%	2540
	11th to 20th	Night	1 2 1 3 2 2 2 2 3 3 78%	2540
	21st to end	Night	1 1 2 1 1 2 2 3 4 83%	2844
August	1st to 10th	Night	2 2 1 2 2 3 3 2 4 4 74%	2848
	11th to 20th	Night	1 1 1 1 2 2 2 3 4 82%	2903
	21st to end	Night	3 2 1 2 2 1 2 1 2 3 80%	3498
September	1st to 10th	Night	2 1 1 2 1 1 1 1 3 4 84%	1900
	11th to 20th	Night	5% 3 1 3 2 2 3 2 5% 5% 70%	1900
	21st to end	Night	4 3 1 3 3 2 2 2 3 6% 70%	2144
October	1st to 10th	Night	5% 4 1 4 2 2 3 2 3 4 69%	2280
	11th to 20th	Night	7% 4 1 4 3 3 3 2 5% 6% 63%	2280
	21st to end	Night	8% 5% 1 4 3 3 4 3 5% 8% 56%	2532
November	1st to 10th	Night	12% 8% 2 5% 5% 5% 4 4 5% 8% 42%	2430
	11th to 20th	Night	14% 7% 2 6% 4 5% 5% 4 6% 10% 37%	2563
	21st to end	Night	9% 9% 2 6% 4 5% 4 4 6% 8% 43%	2660
December	1st to 10th	Night	13% 9% 2 6% 4 5% 4 3 6% 8% 41%	2660
	11th to 20th	Night	17% 11% 3 7% 6% 5% 5% 4 6% 8% 27%	3276
	21st to end	Night	14% 11% 4 11% 7% 6% 6% 4 5% 6% 26%	4862

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	53% 13% 14% 15% 4 1	2539
	11th to 20th	Day	63% 7% 8% 12% 6% 3	2576
	21st to end	Day	51% 9% 14% 18% 6% 2	3146
February	1st to 10th	Day	42% 8% 17% 21% 11% 1	1710
	11th to 20th	Day	43% 7% 14% 23% 12% 2	1712
	21st to end	Day	46% 7% 16% 18% 10% 3	1570
March	1st to 10th	Day	51% 12% 9% 19% 8% 1	3224
	11th to 20th	Day	30% 6% 14% 26% 23%	3490
	21st to end	Day	50% 10% 13% 19% 7% 1	3969
April	1st to 10th	Day	47% 6% 13% 18% 13% 3	2280
	11th to 20th	Day	39% 5% 13% 24% 15% 4	2252
	21st to end	Day	32% 6% 16% 25% 18% 3	2280
May	1st to 10th	Day	28% 5% 9% 27% 25% 5%	4281
	11th to 20th	Day	21% 3 7% 20% 36% 13%	4380
	21st to end	Day	25% 5% 13% 31% 22% 4	4814
June	1st to 10th	Day	30% 7% 13% 26% 19% 4	2660
	11th to 20th	Day	19% 4 9% 27% 32% 9%	2660
	21st to end	Day	14% 3 5% 24% 32% 22%	2660
July	1st to 10th	Day	7% 2 3 11% 17% 61%	4351
	11th to 20th	Day	13% 3 3 11% 20% 51%	4345
	21st to end	Day	9% 2 3 12% 32% 42%	4557
August	1st to 10th	Day	15% 4 4 11% 24% 43%	4076
	11th to 20th	Day	8% 3 3 20% 39% 27%	3976
	21st to end	Day	10% 2 3 22% 35% 28%	4179
September	1st to 10th	Day	9% 3 4 14% 30% 41%	2280
	11th to 20th	Day	18% 4 8% 19% 31% 20%	2280
	21st to end	Day	18% 4 8% 22% 28% 20%	2033
October	1st to 10th	Day	24% 4 10% 19% 25% 19%	1900
	11th to 20th	Day	25% 4 10% 26% 26% 9%	1900
	21st to end	Day	32% 7% 11% 20% 21% 9%	2065
November	1st to 10th	Day	42% 7% 11% 22% 15% 4	1683
	11th to 20th	Day	44% 8% 17% 16% 14% 1	1615
	21st to end	Day	42% 7% 13% 19% 17% 3	1520
December	1st to 10th	Day	43% 10% 12% 19% 13% 3	1520
	11th to 20th	Day	54% 9% 16% 15% 6%	1928
	21st to end	Day	53% 15% 12% 15% 4 1	2794
January	1st to 10th	Night	48% 14% 18% 15% 4 1	4406
	11th to 20th	Night	53% 10% 10% 15% 8% 4	4384
	21st to end	Night	55% 9% 11% 16% 8% 2	4521
February	1st to 10th	Night	41% 8% 14% 23% 12% 2	2470
	11th to 20th	Night	40% 7% 15% 22% 13% 2	2366
	21st to end	Night	40% 8% 17% 20% 12% 3	1884
March	1st to 10th	Night	48% 11% 11% 20% 9% 1	3648
	11th to 20th	Night	30% 8% 11% 31% 20%	3490
	21st to end	Night	47% 11% 16% 18% 8% 1	3684
April	1st to 10th	Night	41% 7% 17% 22% 11% 2	1900
	11th to 20th	Night	37% 6% 16% 23% 14% 4	1879
	21st to end	Night	30% 7% 21% 27% 13% 3	1900
May	1st to 10th	Night	27% 6% 14% 29% 21% 4	2679
	11th to 20th	Night	19% 4 8% 26% 34% 8%	2516
	21st to end	Night	20% 7% 18% 38% 16% 1	2762
June	1st to 10th	Night	31% 6% 16% 32% 14% 2	1520
	11th to 20th	Night	19% 6% 10% 32% 27% 6%	1520
	21st to end	Night	13% 3 8% 29% 33% 15%	1520
July	1st to 10th	Night	6% 2 4 12% 20% 56%	2500
	11th to 20th	Night	13% 2 3 10% 23% 49%	2492
	21st to end	Night	7% 2 5% 13% 35% 38%	2755
August	1st to 10th	Night	14% 2 4 15% 26% 39%	2839
	11th to 20th	Night	7% 3 4 24% 39% 23%	2930
	21st to end	Night	11% 2 5% 28% 27% 26%	3498
September	1st to 10th	Night	7% 2 4 16% 29% 41%	1900
	11th to 20th	Night	16% 4 7% 22% 31% 19%	1900
	21st to end	Night	17% 4 7% 24% 25% 23%	2144
October	1st to 10th	Night	20% 4 9% 21% 27% 19%	2280
	11th to 20th	Night	21% 4 12% 26% 25% 11%	2280
	21st to end	Night	26% 6% 15% 23% 19% 11%	2532
November	1st to 10th	Night	39% 8% 12% 20% 17% 4	2430
	11th to 20th	Night	41% 9% 15% 18% 15% 1	2563
	21st to end	Night	37% 8% 16% 18% 17% 4	2660
December	1st to 10th	Night	38% 9% 13% 22% 16% 2	2660
	11th to 20th	Night	52% 9% 10% 19% 9% 1	3276
	21st to end	Night	51% 12% 11% 18% 6% 1	4862

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	24% 15% 25% 24% 8% 4	180
	11th to 20th	Day	23% 12% 21% 22% 11% 10%	203
	21st to end	Day	18% 11% 18% 24% 21% 8%	407
February	1st to 10th	Day	14% 14% 21% 24% 19% 6%	370
	11th to 20th	Day	16% 16% 22% 24% 16% 5%	383
	21st to end	Day	16% 13% 25% 30% 12% 4	382
March	1st to 10th	Day	22% 17% 28% 21% 11% 2	460
	11th to 20th	Day	17% 15% 25% 22% 18% 4	460
	21st to end	Day	21% 18% 23% 26% 12% 2	506
April	1st to 10th	Day	15% 17% 26% 24% 13% 5%	460
	11th to 20th	Day	19% 15% 22% 22% 14% 8%	452
	21st to end	Day	8% 17% 26% 22% 19% 8%	460
May	1st to 10th	Day	12% 14% 25% 27% 18% 4	463
	11th to 20th	Day	14% 11% 22% 23% 16% 13%	488
	21st to end	Day	11% 9% 18% 25% 22% 14%	529
June	1st to 10th	Day	8% 12% 20% 24% 22% 15%	490
	11th to 20th	Day	6% 16% 24% 21% 21% 11%	490
	21st to end	Day	2 7% 17% 28% 27% 19%	490
July	1st to 10th	Day	4 3 18% 31% 27% 16%	486
	11th to 20th	Day	1 2 20% 29% 28% 19%	484
	21st to end	Day	2 2 14% 28% 32% 22%	531
August	1st to 10th	Day	2 1 17% 26% 30% 23%	487
	11th to 20th	Day	2 5% 14% 25% 31% 23%	477
	21st to end	Day	3 4 16% 28% 29% 19%	539
September	1st to 10th	Day	1 4 19% 23% 36% 16%	490
	11th to 20th	Day	6% 7% 18% 28% 25% 16%	490
	21st to end	Day	6% 6% 20% 26% 30% 12%	490
October	1st to 10th	Day	8% 9% 17% 25% 23% 18%	490
	11th to 20th	Day	11% 10% 16% 23% 28% 13%	490
	21st to end	Day	13% 10% 18% 27% 19% 13%	514
November	1st to 10th	Day	18% 9% 16% 30% 18% 8%	273
	11th to 20th	Day	13% 7% 19% 25% 29% 8%	225
	21st to end	Day	12% 7% 17% 29% 27% 7%	180
December	1st to 10th	Day	17% 12% 19% 26% 17% 9%	180
	11th to 20th	Day	23% 11% 16% 25% 19% 6%	180
	21st to end	Day	13% 15% 23% 25% 23% 2	198
January	1st to 10th	Night	16% 8% 23% 33% 18% 3	760
	11th to 20th	Night	15% 9% 22% 31% 19% 3	760
	21st to end	Night	15% 5% 22% 36% 19% 4	836
February	1st to 10th	Night	11% 7% 24% 39% 18% 1	760
	11th to 20th	Night	15% 8% 22% 35% 18% 2	744
	21st to end	Night	11% 11% 23% 40% 14% 1	628
March	1st to 10th	Night	16% 13% 26% 30% 13% 2	760
	11th to 20th	Night	15% 8% 20% 35% 20% 2	760
	21st to end	Night	15% 11% 26% 33% 15%	836
April	1st to 10th	Night	13% 10% 24% 36% 17% 1	760
	11th to 20th	Night	11% 9% 27% 33% 17% 3	751
	21st to end	Night	10% 8% 23% 37% 20% 2	760
May	1st to 10th	Night	8% 6% 27% 39% 20% 1	467
	11th to 20th	Night	11% 4 20% 39% 25% 2	374
	21st to end	Night	10% 4 20% 40% 24% 1	411
June	1st to 10th	Night	10% 4 16% 43% 27% 1	380
	11th to 20th	Night	6% 6% 24% 45% 19% 1	380
	21st to end	Night	4 1 12% 52% 30%	380
July	1st to 10th	Night	2 1 11% 51% 36% 1	370
	11th to 20th	Night	2 1 10% 54% 33%	368
	21st to end	Night	1 5% 51% 40% 3	463
August	1st to 10th	Night	2 1 3 45% 47% 2	567
	11th to 20th	Night	2 1 6% 43% 43% 5%	616
	21st to end	Night	3 1 10% 42% 41% 3	836
September	1st to 10th	Night	1 3 11% 43% 40% 3	760
	11th to 20th	Night	6% 3 12% 35% 39% 6%	760
	21st to end	Night	5% 3 15% 37% 34% 5%	760
October	1st to 10th	Night	6% 2 17% 40% 32% 4	760
	11th to 20th	Night	8% 4 15% 38% 31% 5%	760
	21st to end	Night	9% 4 18% 38% 25% 6%	836
November	1st to 10th	Night	13% 6% 17% 41% 18% 5%	748
	11th to 20th	Night	15% 7% 21% 36% 20% 2	760
	21st to end	Night	12% 8% 17% 37% 23% 3	760
December	1st to 10th	Night	15% 6% 20% 34% 22% 3	760
	11th to 20th	Night	17% 10% 18% 34% 20% 2	760
	21st to end	Night	18% 11% 24% 36% 10% 1	836

Page generated at 2024-10-30 10:19:22. Version ac07

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