10 AM MST, Sunday, November 10, 2019
A strong cold front is approaching Casper, WY from the north at this hour. It will likely move through the Cheyenne area in the late afternoon and sweep southward through the Denver-Boulder area between 6 and 8PM.
Following the cold front we should see an increase in low clouds and a chance for freezing drizzle toward the midnight hour. After midnight as some higher level ice crystal clouds move over the area, the freezing drizzle is expected to transition to intermittent snow (mainly light). The snow will likely taper off within a few hours of daybreak. Accumulation are likely to vary from a dusting to about 2 inches for the morning commute.
The cloud cover will probably be slow to thin on Monday, and daytime temperatures may fail to get above freezing in the urban corridor. Milder weather should return Tuesday afternoon.
Noon, Friday, November 8, 2019
It looks like we may get an unseasonably warm weekend ahead of the next strong cold front late Sunday. On Saturday, temperatures in the Colorado Springs-Denver-Boulder-Fort Collins corridor may get near 70, and possible back to at least 60 on Sunday. The cold front will probably move through Cheyenne Sunday afternoon, and then move south in the evening through the Colorado Front Range urban corridor.
Like the last cold spell, the cold air mass will be shallow, so the thickest cloud cover and best chance for precipitation will be in the lower foothills and plains. West Slope areas will have only minor changes.
Freezing drizzle is likely Sunday night in and along the lower foothills (mainly below Estes park and Nederland). Some areas of snow may develop by Monday morning causing some light accumulation (around an inch). Although the clouds may thin a bit Monday, it will likely be a mainly cloud day with temperatures only rising to around freezing. Tuesday is expected to bring a return to milder weather.
5:45 AM MST, Tuesday, November 5, 2019
Over the next 5-7 days we are in for at least two cycles where we get a day or two of mainly sunny and mild weather, then a period of mainly cloudy and cold. The mild periods should be today through Wednesday morning, and again Friday and Saturday. The cold spells should be Wednesday afternoon into Thursday morning, and again Saturday evening through Monday. (The next cold period could start by Wednesday morning in Cheyenne.)
Precipitation? There are no organized storm systems, so no major snowfalls are expected. There is a small chance for some light snow or flurries during the cold periods. It is more likely that there will be some low clouds and areas of freezing drizzle in the lower foothills and plains Wednesday evening-Thursday morning, and again on Sunday.
The cold air masses over the next week are shallow and coming from the north and not the west. That means that the changes in weather for the lower foothills and plains will be less noticeable in the high mountains and West Slope. It’s possible that even Nederland and Estes Park will be above the low stratus clouds.
12:45 PM MDT, Monday, October 28, 2019
After a short lull in activity, and maybe some breaks in the overcast this afternoon and tonight, snow is likely to redevelop Tuesday morning from north to south behind another cold front. It may be midday before snow develops south of metro Denver. Snow will likely continue into Wednesday morning and then end from north to south.
This next storm is stronger and better organized than the one we just had, but it is working with less moisture. So although the potential exists for a greater snowfall, the limited moisture may result in a similar amount to what we just had, but no freezing drizzle this time. It does appear that mountain areas (which did not get as much as expected in this last storm) might get a little more with this next one. It also appears that significant snow will spread more onto the high plains of eastern Colorado this time around. Although the winds won’t be as strong as we get in our bigger blizzards, there is likely to be enough wind for some blowing snow and dangerous wind chills, especially east of I-25.
Most likely snow accumulation Tuesday-Wednesday morning
7-12″ Rocky Mountain Park, Nederland, Evergreen, Eisenhower Tunnel
5-10″ Denver-Boulder metro and Cheyenne
3-6″ Fort Collins, Longmont, Colorado Springs
Because it may be cloudy on Wednesday morning, the reduces the chance for a record low (7 in Denver from 1991, 6 in Boulder from 1993). On Thursday morning there is a better chance for clear skies that could allow record lows (10 in Denver from 1991, 5 in Boulder from 1991). The high temperatures in Boulder on Tuesday and Wednesday could be the coldest highs for those dates (record low highs are 26 and 23 both set in 1991). The record low high temperatures in Denver are 25 (Tuesday) and 18 (Wednesday).
The snowfall and record cold should be well over by Halloween evening. But expect snow and the ground and temperatures quickly dropping well below freezing at sunset.
Noon MDT, Saturday, October 26, 2019
We are still looking at a cold wave tonight through Thursday morning with possible record low temperatures and two periods of wintry precipitation, one late tonight through early Monday morning, and the other Tuesday into Wednesday morning.
Snow and freezing drizzle, Saturday night- Monday morning
The one real change since my blog yesterday is that it looks like the potential for a period of heavy snow will probably hold off until Sunday afternoon or night. But that doesn’t mean it will be pleasant before then. After the cold front Saturday night, low clouds and some areas of freezing drizzle and light snow are likely late Saturday night through Sunday morning, with light accumulations possible. Expect icy road conditions, especially Sunday evening and Monday morning.
Most likely accumulation through Monday morning (with most occurring Sunday afternoon or night):
8-12″ mountains & foothills (including Rocky Mountain Park, Nederland, Evergreen, and the approach to Eisenhower Tunnel).
6-10″ in Cheyenne, Boulder, Broomfield, and the Denver area west of I-25 and south of I-70.
3-6″ Colorado Springs, northeast Denver, Longmont, Fort Collins
1-3″ Weld County
Snow, round 2
And even colder air mass and another storm system is forecast to move into the region on Tuesday. Expect snow during the day Tuesday continuing into Tuesday night or Wednesday morning. With this round the heavier accumulations may spread out over the high plains with time. Expect a general 4-8 inches more.
Temperatures are likely to remain below freezing even in the lower elevations Sunday through Wednesday, and maybe Thursday too. The best chance for record low minimum temperatures in Denver and Boulder appear to be Wednesday morning and Thursday morning. The records in Denver for Wednesday and Thursday mornings are 7 and 10, both set in 1991. The record in Boulder on Wednesday morning is 6 (1993) and on Thursday it’s 5 (1991). Record low maximum temperatures are possible in the Monday through Wednesday period as well.
12:15 PM MDT, Friday, October 25, 2019
Enjoy the mild autumn weather today and Saturday. A cold front Saturday evening (maybe afternoon in Cheyenne) is expected to begin a 4 or 5-day period with much below average temperatures. Significant snow is likely Saturday night through Monday morning, with perhaps another period of snow on Tuesday as an even colder air mass arrives.
The first period of snow is likely to spread north-to-south from Cheyenne to Colorado Springs Saturday evening and night, and continue until late Sunday night or Monday morning. It appears that there can be periods of moderate or heavy snow alternating with periods of lull in the action. Most likely accumulations through Monday morning:
8-14 inches in the mountains from Rocky Mountain Park south through the Pikes Peak region, and in the Palmer Divide region.
6-10 inches: Denver (south and west sides), Broomfield, Boulder, Cheyenne
2-5 inches: DIA, Longmont, Fort Collins, Colorado Springs
I will update these numbers tomorrow if necessary. Additional snow is possible on Tuesday.
Sunday and Monday in Denver-Boulder are likely to stay below freezing during the day with teens on Monday morning (assuming cloud cover does not let it get colder). An even colder air mass on Tuesday should result in temperatures barely making to 20s, and falling to the single digits at night. The record low on Tuesday for both Denver and Boulder is -2 (the October record) and that will likely stand. On Wednesday we have a shot at a record if skies clear out Tuesday night. The record for Wednesday in Denver is +7 (1991) and for Boulder it is +6 (1993).
There is some disagreement in weather models about how quickly this very cold air mass will release its grip. Some have milder weather starting to return on Halloween while others keep it quite cold until then.
6:00 AM MDT, Wednesday, October 23, 2019
Today will turn colder after a mild morning with clouds and snow this evening. The best chance for significant snow is south and west of Denver. The northeastern plains north of Denver may see little or no snow. The snow should end Thursday morning.
Most likely accumulations:
6-10 inches: mountains, foothills, and Palmer Divide region of Douglas, Jefferson, and Gilpin Counties.
3-6 inches: Nederland, Rocky Mountain Park, Castle Rock, Colorado Springs, southwest suburbs of Denver.
2-4 inches: Boulder, Broomfield, Denver
around an inch: DIA, Longmont, Cheyenne
less than 1 inch: Fort Collins, Weld County
Next Chance Sunday
After a couple mild days Friday and Saturday, a multi-day period of colder than average temperature will likely begin on Sunday. Snow during that period is a little uncertain now, but it appears that there may be some on Sunday. More on that later.