For the mountains, dry and sunny Thursday, Friday, and Saturday. For the foothills and plains east of the mountains, much colder air will move in Thursday night so expect snow (light accumulations) and below freezing temperatures for the foothills with near freezing temperatures for the plains. Bring in sensitive plants!
It'll be a tale of two halves on Thursday and Friday as the mountains west of the divide will see sunny and gorgeous weather while the foothills and plains east of the divide will see very cold air, clouds, and likely some snow.
The cold air and snow is being reported in eastern Wyoming as of Thursday morning, and this will move south into Colorado by Thursday late afternoon and evening.
Current weather conditions as of 8am Thursday morning. Red numbers show the temperature while asterisks show snowfall. The map is centered on Wyoming with Colorado at the bottom-right of the image. Source: NCAR/NOAA
Right now as of Thursday morning, clouds are already covering parts of Colorado east of the mountains and north of Denver, and this will likely hang on throughout the day.
By Thursday late afternoon, the cold front will blast south along the front range, hitting Ft. Collins, Denver, and then pushing through Colorado Springs and the southeastern plains by evening. As the front moves through, look for gusty winds from the northeast, a few rain showers, and potentially a few thunderstorms east and south of Colorado Springs.
By the time the sun goes down around 715pm, temperatures will likely be cool enough for snow in the foothills north of Denver and above about 7,000ft. Elsewhere, there could be a few rain showers as temperatures continue to cool through the evening.
By about midnight Thursday night, temperatures should be cool enough over most of Colorado, including the lower plains, to support snow falling from the sky. The best chance for snow will last until about 4am and then most precipitation should end.
Any accumulations should be pretty light (dusting), with two exceptions. First, the foothills and palmer divide above about 6,000ft have the best chance of being cold enough to support accumulating snow. Second, there could be a few bands of heavier snow that stretch from west-to-east across the foothills out to the plains, generally north of Denver. Any locations under these bands could see a quick inch or two of accumulating snow.
Snow forecast for Thursday and Friday shows light accumulations in eastern Wyoming and Colorado. Source: NWS
Zoom of the same snow forecast above. Source: NWS
On Friday, the mountains will wake up chilly but under sunny skies while areas east of the mountains will see chilly temperatures and low clouds for at least Friday morning, perhaps lasting through most of the afternoon.
On Saturday, the entire state should be sunny and dry, so enjoy!
For Sunday through next week, most days should be partly to mostly sunny with just a low chance of a quick afternoon shower over the mountains. On Friday there could be a few more showers and another batch of cool air for areas east of the mountains, but that's a long way off and very uncertain.
I hope you're loving the approaching cold front and the chance to see flakes on Thursday night, and are then looking forward to a glorious weekend!
Mountain weather will be mostly dry and tranquil Wednesday through the weekend. Along and east of the divide, expect showers on Wednesday morning, a strong cold front and snowflakes on Thursday night, then a chilly day on Friday with warmer temperatures for the weekend.
As the rain showers moved across the state on Tuesday night, temperatures cooled enough to produce snow down to about 11,000ft, mostly in the mountains along and north of I-70. Here are a few webcams that showed the snow as as of about 8am Wednesday morning.
Snow fell on many mountains over 11,000ft last night. "RMNP" means "Rocky Mountain National Park". Most of these webcams are positioned around 11,500ft. Source: Mountain Cams / OpenSnow.com
The last of the rain showers are now moving through eastern Colorado on Wednesday morning, while sun breaks out over the western mountains.
Wednesday morning radar. Source: Weathertap.com
In total, this storm dropped anywhere from 0.50 inches up to 3.0 inches. The map below is mostly derived from radar, and since radar doesn't do well in the mountain because the radar beam is sometimes blocked, I have a feeling that some mountain areas picked up more than what the map shows.
Estimated rainfall from the storm. Source: NWS
Wednesday and Thursday will be nice days over the mountains while the plains east of the mountains deal with low clouds on Wednesday and then a nice day on Thursday.
The next big weather story is a strong cold front that will move through Colorado on Thursday evening.
Most mountain locations won't see much of an effect from this front as temperatures will cool a few degrees Thursday night with frost possible in the north, and that's about it.
However, the foothills and plains east of the divide will see temperatures plummet on Thursday evening and a chance for snow and freezing temperatures on Thursday night. Elevations over 6,000ft have the best chance to see accumulating snow and temperatures at or below 32F on Thursday night. For the bigger cities (Denver, Boulder, Ft Collins, etc), expect some snow flakes mixed with rain drops on Thursday night with temperatures hovering around freezing, but likely just above. For a few hours on Thursday night the jet stream will be overhead, and this could produce a few bands of heavier precipitation. This heavier precipitation could cool the air enough to drive snow down to the lower elevations, so watch out (hope!) for this to happen. Overall, this cold front and possible snow shouldn't affect driving around the cities, but the foothills should turn white with at least a dusting!
Forecast low temperatures on Friday morning. It'll be close to freezing over the eastern plains, so bring in your sensitive plants just in case! Source: Weatherbell.com
Saturday and Sunday will be dry for all of Colorado with average-ish temperatures. Most of next week looks dry as well, with just a low chance of an afternoon shower over the mountains around mid week. Overall, after the cold front on Thursday night, it looks like we're in for at least one week of calm, beautiful September weather. Get out to enjoy it!
One more day of cloudy and rainy weather on Tuesday for the mountains, then Wednesday and Thursday will be much drier. Look for a strong cold front to bring near or below freezing temperatures and a bit of snow to northern and eastern Colorado on Thursday night. Then Friday through the weekend will be sunny with warming temperatures.
Rain moved through most mountain areas on Monday afternoon and Monday night, and more will cover the area on Tuesday. The whole day won't be a washout, but with lots of clouds and showers around, it won't be a glorious day (unless you like hiking in the rain, in which case, get out there!).
Tuesday morning radar showing plenty of rain over and heading into Colorado. Source: Weathertap.com
The last part of the storm will push through the state late Tuesday night into Wednesday morning, and this will be the most likely time that the highest peaks over 12,000ft could see a few inches of snow. If a few heavier showers move through during this time, snow flakes could even get down to 11,000ft for areas along and north of I-70.
On Wednesday, most of the state will return to drier and sunnier weather, with the exception of low clouds hugging the continental divide as well as the foothills and plains east of the divide.
For Thursday, look for a very nice day, with a massive change coming during the evening hours. A strong cold front will hit the Wyoming border by late afternoon and then push south through the evening. The brunt of the cold air will stay along and east of the mountains, though some of this air will filter through northern Colorado, perhaps getting toward I-70. On Thursday night, bring in any plants that you want to live as temperatures will flirt with freezing for many of the lower elevations and will definitely get below freezing in the higher valleys and mountains. There could also be some light drizzle, freezing drizzle, or snow flakes in the eastern foothills and the plains up against the eastern foothills, so keep an eye to the clouds on Thursday night.
Forecast low temperatures on Friday morning. Source: Weatherbell.com
Friday will be chilly and cloudy east of the divide but sunny and glorious elsewhere. Temperatures will warm on Saturday and Sunday with likely no chance of rain either day, so enjoy the perfect fall weather.
Looking ahead to next week, I don't see much weather action except for perhaps a few showers and a bit cooler air near the middle or end of the week.
On Monday and Tuesday, clouds and frequent rain showers will cover the mountains, then a cold front will hit the front range on Thursday with very chilly temperatures for Friday morning. Snow will accumulate on some peaks on Tuesday night, and flakes could also fall in the eastern foothills on Thursday night.
The moisture surge is working its way into Colorado this morning with rain showers showing up on radar over our mountains and extending back to Utah, Nevada, California, and especially Arizona.
Monday morning radar. Source: Weathertap.com
The most likely time for heavier and steadier rain in the mountains will be from Monday night through Wednesday morning when we could measure about 1-3 inches of rain. There might be a few flakes of high-elevation snow (above 13,000ft) on Monday and Tuesday, but the best chance of mountain snow will be on Tuesday night above about 11,000ft. Wednesday will be a much drier day, but clouds could hug the peaks of the central and northern mountains with some leftover showers.
The American GFS model is predicting a few inches of rain for most mountain areas. Don't focus on the points of heavier rain -- this isn't necessarily accurate and is a reflection of the model's lower resolution. Source: Weatherbell.com
For Thursday and Friday, the weather in the mountains will be rather tranquil while the action shifts to the east of the mountains. A strong cold front will push in from the north on Thursday which will drop temperatures into the 30s on Thursday night through Friday morning.
It is possible that the foothills east of the divide and some higher-elevations of the plains could see some snow flakes on Thursday night. It's also possible that some locations on the plains drop to close to freezing on Thursday night, with a good chance of this happening above about 6,000ft. This forecast is colder than previous forecasts as the models have been trending a bit chillier, and they also tend to underestimate the strength of the cold air.
Temperature difference from average on Friday morning. The average low temperature in Denver is about 50 degrees, and actual readings could be closer to 35 degrees. Source: Weatherbell.com
By midday Friday, clouds will clear east of the mountains and the whole state should see a dry and sunny day. Saturday should also be dry and sunny for the entire state. Then mountain showers could return for Sunday and Monday, but I have low confidence in the forecast after Saturday.
A few scattered showers on Sunday, then steady rain and thunderstorms will hit most Colorado mountains from Monday afternoon through Wednesday morning with significant rain. Wednesday afternoon through Saturday will then be dry over the mountains with chilly air and some clouds / drizzle over the eastern plains and front range cities.
Sunday will be much like Saturday with midday and afternoon showers and a quick thunderstorm. Nothing too interesting.
The fun, or perhaps flooding, will start on Monday and last through Wednesday morning. A ton of tropical moisture from the southwest will cover Colorado during this time, with some of the moisture coming from Hurricane Norbet which will slowly dissipate off the Baja coast.
From Monday afternoon through Wednesday morning, look for 1-3 inches of rain for most of the mountain areas of Colorado, with less than that east of the mountains. The rain will come in a few waves of steady precipitation and thunderstorms, and it will fall both during the day and during the nights. Some areas could see flooding, while most should just see beneficial rains.
Total rainfall forecast from the storm. Areas of Nevada, Arizona, and Utah may get double the amount of rainfall received in Colorado. Source: NOAA
Most of the moisture and rainfall will be over by Wednesday morning or midday, though the mountains along the divide and mostly along and north of I-70 could see showers persist on Wednesday afternoon and Wednesday evening.
Then after the storm, the big story for Thursday, Friday, and Saturday will be cold air covering the plains east of the mountains. A cold front should move through on Thursday morning-ish, and low temperatures on Friday morning east of the mountains will likely be in the upper 30s and low 40s, with perhaps below-freezing temperatures in the foothills above 7,000ft or so. Also, expect some low clouds / fog / drizzle east of the mountains on Thursday afternoon perhaps into Friday morning. In contrast, the mountains west of the divide will not see this cold air and will record normal September-like temperatures.
In terms of snowfall, there might be a bit on the highest peaks on Monday and Tuesday, with the best chance of a mountain dusting coming on Tuesday night into Wednesday morning for the northern half of Colorado (roughly from Crested Butte north to Wyoming).
Have a great Sunday and go Broncos!