Saturday, January23, 2021
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Marine Weather and Tides
Denver, 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 7:12AMSunset 5:10PM Saturday January 23, 2021 1:46 AM MST (08:46 UTC) Moonrise 1:53PMMoonset 3:50AM Illumination 75% Phase: Waxing Gibbous; Moon at 10 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 Denver, CO
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location: 39.76, -104.88     debug


Area Discussion for - Denver/Boulder, CO
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FXUS65 KBOU 230431 AFDBOU

Area Forecast Discussion National Weather Service Denver/Boulder CO 931 PM MST Fri Jan 22 2021

UPDATE. Issued at 915 PM MST Fri Jan 22 2021

The main adjustment to the forecast was to blend in short term models into the PoP forecast across the mountains through the next 18-24 hours. This mainly lowered the PoPs in most areas except for the Park Range and RMNP area. Satellite and model data both indicate that there will be periods of dry weather between heavier bands of snow in the mountains. The snow amount forecast was left unchanged as the Park Range mountains are expected to see the heaviest amounts. The first batch of radar returns are showing up on the Grand Junction radar which are expected to reach the Park Range shortly.

The only other thing worth noting is that there is some potential for freezing drizzle right at the base of the foothills late Saturday night and into Sunday morning. The moisture does not look deep enough for widespread freezing drizzle but there may be just enough moisture to create slick roads at the base of the foothills.

SHORT TERM. (This evening through Saturday) Issued at 230 PM MST Fri Jan 22 2021

Snowfall will increase slightly in intensity and areal coverage this evening and overnight as WNW flow aloft shifts more W then WSW ahead of the incoming trough, but should remain confined to the mountains and some parts of the northern foothills. Mild subsidence aloft will also be replaced by weak ascent ahead of the trough, though models are in good consensus about the best forcing missing northeast Colorado. The forecast area will be under the left exit region of a roughly 100 kt jet streak on Saturday night, which should also provide a dynamic boost by increasing mid level divergence and orographic flow. We have kept a Winter Weather Advisory in effect for the the Park Range and part of the Gore Range in Grand County from 5 PM this afternoon through 11 PM Saturday, expecting the greatest snow accumulations of 4 to 10 inches with gusts up to 35 mph in this area. Continue to expect less accumulations of 1 to 5 inches elsewhere above 10 kft. Expect lows tonight between 1 and 5 degrees warmer than last night across most of the area, putting much of the plains in the low to mid 20s F, foothills mid to upper 20s F, and mountains mid teens.

Light snowfall will continue Saturday morning and probably through the day, intermittent except in the highest terrain. A weak front is expected in the early evening across the plains, which will likely not impact temperatures much being after the high but should bring some moderately gusty northwesterly winds. Highs Saturday are forecast to be similar to highs today though a few degrees warmer across much of the plains, reaching the low 50s F in much of the area adjacent to the Palmer Divide. Behind the front there is a chance of some light snowfall during the afternoon/evening hours spreading east from the foothills over the urban corridor to about I-25, north of I-70, and across the plains of northern Weld County as well, but looks to be only flurries at this time.

LONG TERM. (Saturday night through Friday) Issued at 230 PM MST Fri Jan 22 2021

The short wave cutoff trough is across SoCal late Saturday into Sunday. On Sunday the low becomes vertically stacked and then absorbed into the westerly flow as a weak open wave overnight into Monday. Besides being vertically stacked, it begins to get absorbed into a broader upstream trough as a stronger west coast trough digs southeast across Oregon and California. What that means is synoptic forcing and moisture advection across our area with the first tough will be weak. There will continue to be snow showers in the mountains into Sunday morning given SW flow and really good lapse rates, but without another source of lift the amounts will remain on the light side and only minor travel impacts are expected. There will be a lull in snow across most of the area during the day on Sunday until the weakening trough gets kicked east/absorbed and the first trough axis moves across Colorado late Sunday into early Monday. Snow showers should arrive mainly along and south of I-70 overnight into Monday morning, but again amounts will be very light, T-2" or so. The plains should remain dry other than maybe the Palmer Divide and some flurries for the eastern foothills and west/south suburbs of Denver late Sunday into early Monday.

On Monday the stronger trough digs south across CA and builds a progressive ridge that moves across Colorado throughout the day. Thus, our area should remain dry on Monday during the daylight hours. Despite SW flow aloft afternoon, cold advection will occur and will keep temperatures in check. Across the plains highs should be in the 30s, but in and around Denver metro may top 40 degrees. The mountains will be in the 20s. Winds will be on the light side across the area with the ridge moving overhead.

On Tuesday models in general are still having trouble agreeing on the evolution of the trough. The EC is more progressive and brings it ENE across southern Colorado, while the GFS is slower bringing it across central Colorado. The GFS solution would be a wetter solution for us with slower movement and better lift across our area. Neither solution would favor deep east/northeast upslope component, and QG lift is meager. Even the jet would be too far south as a source of lift. Orographics will be the primary mechanism for lift across the area with shallow upslope across the plains and WSW flow across the mountains. Looking at the ensemble output, the GEFS would favor snow across the plains, but the ensemble mean liquid equivalent is about 0.1-0.3" depending on location relative to terrain. The faster EC is about half that for the plains and I- 25 urban corridor. Both ensembles have little spread indicating confidence (for now) of light snow across the plains. In the mountains, relying again on just orographics and lapse rates means light snow as well.

Models agree that Wednesday will be dry across the area with yet another west coast trough building a ridge that moves across Colorado throughout the day. 700 mb temps warm 10 degC by early Thursday but not soon enough for Wednesday's high temperatures. It looks to remain a little below normal across our area for late January. Highs across the plains should be in the low 40s, 30s in the eastern foothills, and 20s in the mountain valleys. Thursday also looks dry as another storm system digs south across California and generates increasing southwest flow aloft. Should be enough warm advection in the flow to result in highs above normal.

AVIATION. (For the 06Z TAFS through 06Z Saturday night) Issued at 915 PM MST Fri Jan 22 2021

VFR expected through the day on Saturday. Drainage winds will become light and variable for much of the morning tomorrow. By the afternoon, there may be a brief period of gusty northwesterly winds but they are not expected to last very long. By the evening, a cold front will push across the area with northeasterly winds behind it. Low clouds with ceilings likely in the MVFR range are expected to develop behind this front and last well into the morning Sunday. There is a slight concern for fog to develop overnight Saturday night but the moisture does not look deep enough at this time.

BOU WATCHES/WARNINGS/ADVISORIES. Winter Weather Advisory until 11 PM MST Saturday for COZ031.



UPDATE . Danielson SHORT TERM . Direnzo LONG TERM . Schlatter AVIATION . Danielson


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Denver, Denver International Airport, CO13 mi54 minNNE 310.00 miA Few Clouds28°F18°F66%1006.9 hPa
Denver - Centennial Airport, CO14 mi54 minN 010.00 miA Few Clouds27°F17°F66%1007 hPa
Broomfield / Jeffco, CO16 mi52 minNW 310.00 miFair30°F19°F64%1007.4 hPa
Erie Municipal Airport, CO19 mi52 minN 010.00 miFair19°F16°F88%1007.8 hPa

Link to 5 minute data for KBKF

Wind History from BKF (wind in knots)
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Last 24hrS5SE3NE4NE5E4CalmSW4S6SW3S11S10S12S13S17S13SW14SW9SW8CalmE3CalmE3NE3W16
G21
1 day agoCalmN3N4N6N3NE6N8NE7NE9N4CalmE4E3CalmS4S3S5S5S3S5S4CalmS3S6
2 days agoN5W6NW15NW8W7W11NW14
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E10NE5CalmNW4N5N9N12NE8NE8NE6

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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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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.