Thursday, October22, 2020
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Marine Weather and Tides
Castle Pines, CO

Version 3.4
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8/26/2020 The 7 day forecast is taking about 5 seconds to load but it will eventually load. NOAA is still working on it.
8/18/2020 NOAA continues to have trouble. Wind guest will occasionally be left off graphs. I am working with NOAA to resolve the issue.
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 7:16AMSunset 6:11PM Thursday October 22, 2020 5:17 PM MDT (23:17 UTC) Moonrise 1:54PMMoonset 11:21PM Illumination 36% Phase: Waxing Crescent; Moon at 6 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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7 Day Forecast for Marine Location Near Castle Pines, CO
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location: 39.45, -104.89     debug


Area Discussion for - Denver/Boulder, CO
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FXUS65 KBOU 222150 AFDBOU

Area Forecast Discussion National Weather Service Denver/Boulder CO 350 PM MDT Thu Oct 22 2020

SHORT TERM. (This evening through Friday) Issued at 350 PM MDT Thu Oct 22 2020

An upper trough axis is passing across the area, however conditions on either side of the Continental Divide are drastically different. On the east side over the plains and up to about 9500 feet up the lee of the Front Range mountains and foothills, a cold front has brought cold temperatures, a sharp increase in humidity and areas of drizzle and fog. West of the divide and into the high mountain valleys, warmer than average temperatures combining with very low humidity and wind gusts to 45 mph creating terrible fire weather conditions. Luckily on this side of the divide, this moist upslope conditions should stick around all night and into the morning. However it will create areas of freezing drizzle then likely switch over to light snow flurries after midnight when temperatures through the saturated column get cold enough. Not a lot of moisture with it, not expecting more than half an inch, with it mostly concentrated over the foothills. Commuters will need to be careful however, especially over bridges and overpasses where the roads may be a bit slick in the morning.

West of the divide tonight, winds will begin to decouple near sunset, and speeds should be decrease especially in the valleys, lessening the fire weather concerns. It may take Grand County near the fire a bit longer to decouple with the fire being about to mix some of the stronger winds aloft down. Cold temperatures overnight with lows in the teens to mid- 20s over entire forecast area, and good humidity recovery should help keep fire activity down overnight.

The northwesterly flow on the backside of the exiting trough will switch more westerly Friday, keeping warm and dry weather over west of the divide, however wind speeds will be slightly weaker. Look for mostly clear skies and temperatures about 10 degrees cooler than today. East of the divide, high pressure over the Great Plains will keep in the cool weather with easterly to southeasterly surface winds. Temperatures will only top out into the upper 30s to low 40s.

LONG TERM. (Friday night through Thursday) Issued at 350 PM MDT Thu Oct 22 2020

. STRONG, GUSTY WINDS SATURDAY OVER THE MOUNTAINS AND HIGHER FOOTHILLS . THEN MUCH NEEDED SNOW AND COLDER TEMPERATURES LATE THIS WEEKEND INTO EARLY NEXT WEEK .

Cross mountain flow will increase to 40 to 50 knots Friday night and Saturday in response to the tightening mid level gradients ahead of an approaching storm system. This will bring strong, gusty winds to the mountains overnight, and then spreading to lower elevations including the high mountain valleys and a good chunk of the foothills Saturday. Peak wind gusts over 60 mph expected on the higher mountain slopes, with gusts around 40 mph expected in the mountain valleys and foothills. Fire danger and potential for rapid fire spread will increase with this bout of wind.

Then, a significant change in the weather is still expected to much needed snow and cold. This will arrive Saturday evening as a strong cold front arrives. The precipitation may lag the front by several hours, depending on how fast the upper level support and deeper moisture arrives. Right now, we think snow will get going over the northern half of the area (mainly north of I-70) Saturday night, and then spread south across the entire forecast area Sunday. Snow is then expected to decrease Sunday and probably come to an end in most areas Monday.

There is still considerable uncertainty with regard to accumulations. The reason is for a few few factors. This is a splitting trough and we now have increasing confidence that the main piece of energy will sink south/southwest into the Great Basin and Desert Southwest. However, we do have an opportunity to get into the right rear entrance region of the upper jet. There would also be a nice band of deep frontogenesis along the mid level thermal gradient. If these two features can drop across the area and hold in place long enough, we could see a few bands of heavier snowfall. If they don't then we'd only see occasional light snowfall and much lighter accumulations. Right now, our forecast is leaning toward the middle range of ensemble output counting on national guidance and a little banding, giving potential for 3-6" across the plains and several inches to locally a foot or more in some of the mountains. Again, if the event falls apart, as many have during this drought, then we'd bee seeing lighter amounts.

Temperatures will be very cold, and have pushed the guidance colder than national blend and toward the colder side given growing confidence and clustering of model data. High temperatures will likely only be in the lower 20s, which means we'll be close to breaking the all time record low max for Sunday the 25th (21F), and almost assured of breaking that on Monday the 26th (31F).

Slow moderation in temperatures are then expected through the end of next week.

AVIATION. (For the 18Z TAFS through 18Z Friday afternoon) Issued at 350 PM MDT Thu Oct 22 2020

The second surge is currently pushing in, bring gusts 25 to 35 knots. Northeasterly winds and low clouds are expected to persist through the night and into Friday morning. Some areas of freezing drizzle will occur tonight, with some flurries mixing in after midnight and into the morning. Winds will remain northeasterly all night, then begin to swing out of the southeast by Friday noon. Ceilings will be improving after 15-17Z timeframe.

FIRE WEATHER. Issued at 350 PM MDT Thu Oct 22 2020

Dry and breezy conditions continue west of the divide this afternoon, with gusts to 45 mph and humidity in the teens. Luckily east of the divide, the cold front push has made it all the way up to about 9500 feet, bringing refreshing humidity in the 70-80 percent range. The drier part of the cold front is charging down North Park now, with northerly gusts to 40 mph along with humidity jumping from the teens to the 40 percent range. This front should spread south into Grand County, then as the evening progresses, the winds should decouple and most mountain locations should have good recoveries. Cooler temperatures tomorrow however still looking for near critical humidity. Winds will be slightly lighter and will take longer to mix in, but still expecting winds to approach criteria. Not confident we'll hit criteria, but the impact is enough to issue a Fire Weather Watch. East of the Divide, the westerly winds will start eroding the weakening cold frontal airmass, so some of the drier and breezy conditions may start backing down the lee of the Front Range mountains.

Westerly flow aloft will increase Friday night and Saturday. This will bring another round of strong, gusty winds to the mountains overnight Friday night, and then spreading to lower elevations including the high mountain valleys and a good chunk of the foothills Saturday. Peak wind gusts over 60 mph expected on the higher mountain slopes, with gusts around 40 mph expected in the mountain valleys and foothills. Fire danger and potential for rapid fire spread will increase with this bout of wind. One good thing is humidity levels will improve from those readings seen in the high country the last several days. Humidity recovery of 50-65% expected Friday night, and the minimum humidity of 25-35% Saturday. This is clearly above Red Flag criteria, but given strength of winds in heavy fuels we want to message the potential conditions through the use of a Fire Weather Watch at this time.

BOU WATCHES/WARNINGS/ADVISORIES. Red Flag Warning until 7 PM MDT this evening for COZ212>214.

Fire Weather Watch from Friday afternoon through Saturday evening for COZ211>214-217-218.

Fire Weather Watch from late Friday night through Saturday evening for COZ215.



SHORT TERM . Kriederman LONG TERM . Barjenbruch AVIATION . Kriederman FIRE WEATHER . Kriederman


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Denver - Centennial Airport, CO8 mi25 minNNE 98.00 miOvercast38°F28°F68%1017.6 hPa
Buckley Air Force Base Airport, CO21 mi20 minNNE 1310.00 miOvercast38°F28°F71%1018.3 hPa
Elbert Mountain - Monument Pass, CO21 mi43 minN 13 G 1710.00 miOvercast32°F28°F87%1018.3 hPa

Link to 5 minute data for KAPA

Wind History from APA (wind in knots)
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Last 24hrW8N10S5S4E8SE6SW10S10S8SW3W7N5NW8NE3N8N8N7N8N10N10N9N11N8NE9
1 day agoE7NE8E4E3SE5S5S11S13S16
G26
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3S3SE7SE5N4N4Calm4N7N11N5
2 days agoN7CalmSE3SW3CalmS6S5S7S6E9SE4SE4NW4E3SW5SW8E5NE4NE7NE9NE8E12
G19
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Tide / Current Tables for
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Weather Map
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NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Ground Weather Radar Station Denver/Boulder, CO
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The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerous of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.