Marine Weather and Tides
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.
6/2/2019. Many thanks to a user for reporting an error on one of the Edit pages. The switch to PHP 7.2 caused many pages that previously worked to quit working. I fixed many but I still depend on users to report ones I missed. Please report errors HERE or send an email to me at L-36.com. Allen
|Sunrise 7:03AM||Sunset 4:38PM||Monday December 9, 2019 10:41 AM MST (17:41 UTC)||Moonrise 4:12PM||Moonset 5:16AM||Illumination 95%|
7 Day Forecast for Marine Location Near Calhan, COHourly EDIT Help
Area Discussion for - Denver/Boulder, CO  (on/off)  Help NOTE: mouseover dotted underlined text for definition
FXUS65 KBOU 091248 AFDBOU
Area Forecast Discussion National Weather Service Denver/Boulder CO 548 AM MST Mon Dec 9 2019
UPDATE. Issued at 547 AM MST Mon Dec 9 2019
A few snowbands stretching out over the northern and western suburbs as well as the northern plains this morning is likely being induced by a little jet max as well as surface convergence. This has disrupted the stratus over the Denver area and against the Palmer Divide and foothills, making it dissipate earlier than expected. Though still expect it to reform and persist through the morning as winds should be weak upslope.
SHORT TERM. (Today and tonight) Issued at 355 AM MST Mon Dec 9 2019
An upper trough will drop southeast across the state this morning, with moisture levels decreasing. The northwest flow aloft is favored in our mountains, so having an expiration of the Winter Weather Advisory in the late morning remains good. Snow will continue in the high country, with another 1 to 4 inches possible through the day. Wind gusts up to 40 mph will continue to cause areas of blowing snow. A cold frontal passage last night pushed in low stratus up against the foothills and Palmer Divide, covering parts of the metro area. The northwesterly surface winds over the plains will continue to make a clockwise turn into the foothills, keeping these low clouds in until late morning at least, with some hints of it lasting into the early afternoon in the foothills of Boulder and Larimer counties. Some isolated snow showers will be found over the northern plains early this morning, but these should drift east and dissipate by sunrise. The rest of the plains should remain dry, though the areas under the stratus could end up producing some flurries or light snow showers. A bit of low level instability looks to form over the Palmer Divide later this afternoon as surface winds converge over the area, have added a slight chance of snow showers.
Another jet will push south from the Northern Rockies tonight to create some lift, just enough to squeeze out any remaining moisture in the orographic flow. Have added some light snow showers over the northern mountains to account for this. Expecting less than 2 inches over the 12 hours, however winds will increase with gusts up to 55 mph to cause more blowing snow.
LONG TERM. (Tuesday through Sunday) Issued at 355 AM MST Mon Dec 9 2019
Models are in pretty good agreement with the pattern change that will take place in the latter part of this week, which could lead to significant snow and wind in the Colorado mountains Friday into next weekend.
For Tuesday, we'll see some moderation in temperatures with westerly flow and warm advection just off the deck. There will likely be some mountain wave clouds to contend with, and lee troughing will be weak. Therefore, valley areas will struggle to break out of the colder temperatures, while Denver and the mountains will see highs rebounding closer to normal. Gusty winds to around 50 mph can be expected over the mountains and wind prone areas of the foothills, as cross sections shows a mountain top stable layer and cross mountain component of 30-40 knots.
Wednesday should feature continued moderation with mid level warm advection. However, a backdoor cold front could slip across the northeast plains keeping temperatures cooler there. Thursday should see similar conditions. Dry weather will persist Tuesday through Thursday.
The weather pattern for us will change by Thursday night and Friday as a powerful 140+ knot jet moves off the Pacific. Ensembles continue to point toward a plume of high integrated vapor transport (2-3 standardized anomalies) reaching Colorado. This, in combination with strong orographics, relatively high 700-500 mb specific humidity levels of 2+ g/kg, and proximity of the upper level jet should result in a period of significant mountain snow/blowing snow. There is potential for more periods of significant snow/blowing snow into Sunday depending on the evolution of the Pacific jet stream and location/depth of embedded short waves. The vast majority of the models/ensembles are now trying to point to another wave late Saturday or Sunday. This one would bring a better chance of accumulating snow onto the plains as well, given the expected forcing and return to upslope flow behind a frontal passage. Until then, we could very likely see bouts of gusty downslope winds along the Front Range and adjacent plains. Temperatures will turn colder and drop below normal for much of next weekend behind the frontal passage.
AVIATION. (For the 12Z TAFS through 12Z Tuesday morning) Issued at 547 AM MST Mon Dec 9 2019
Post frontal northerly winds have veered around to the east- southeast, forming the low stratus affecting the terminals early this morning. A snowband over the northern plains and northern and western suburbs have disrupted the strength of the stratus deck though and dissipated it, clearing it out of the terminals faster than thought. Though there's a chance it could reform, most likely near APA and BJC. If it does, ceilings will be around 1000 feet through about 16z, with the clouds beginning to scatter out by 18Z. Clouds should clear out, with only high clouds after 00z, with winds returning to drainage tonight.
BOU WATCHES/WARNINGS/ADVISORIES. Winter Weather Advisory until 11 AM MST this morning for COZ031- 033-034.
UPDATE . Kriederman SHORT TERM . Kriederman LONG TERM . Barjenbruch AVIATION . Kriederman
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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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Wind Forecast for Denver/Boulder, CO (12,3,4,5)(on/off)  Help
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