Monthly Archives: September 2014

Very warm; cooler/wetter by Monday

10:00 AM Friday, September 26, 2014.

Hello All:

Today’s record high in Boulder is 88 and in Denver it’s 90.  We will get close but most likely stay below records. Above average temperatures and dry weather are likely in the Denver-Boulder-Fort Collins area into early afternoon Sunday.

A large, wet, and slow-moving storm system will be moving from southern Nevada to southern Wyoming in the Saturday to Tuesday time frame. That track would keep the heaviest precipitation to the west and north of the Front Range corridor. But the second half of the weekend is likely to be wet in Utah and western Colorado. I wouldn’t be surprised to see some news stories by late Monday regarding local flooding in the mountains of Utah and/or Wyoming.

For the Front Range the is a small chance for showers or thunderstorms late Sunday and a little better chance on Monday & Monday night with cooler temperatures, but not cold. If the storm track shifts a bit to the south, Monday could be quite wet in the Denver-Boulder area, but that appears unlikely at this time. Snow levels should be high, mainly above treeline.

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Weekend: Mild, some clouds and rain around

Friday, September 19, 2014, 1:15 PM MDT.

It looks like we will have a mild & occasionally wet early autumn weekend. Actually, autumn doesn’t officially begin until 8:29 PM MDT Monday. But Sep-Oct-Nov are considered meteorological autumn, the transition months between the hottest three months and the coldest three months.

The 80+ degree temperatures that we have seen in the low elevations will cool by about 10 degrees Saturday and possibly even a little cooler on Sunday.  The chance for some intermittent showers or thundershowers comes back too for the afternoons and evenings. Sunday looks like it will have a better chance for rain than Saturday.

The current pattern will not result in any exceptionally wet, dry, cold, or hot weather through early next week. So it may be a good weekend for aspen peeping and elk watching as long as you prepare for some spells of clouds and rain.

update: Mainly wet tonight, with some chance for snow

4:15 PM, Thursday, September 11, 2014

It still looks like a drizzly period through Friday morning punctuated by some areas of rain this evening, and rain or snow after midnight.

In addition to the low stratus clouds that have been over eastern Colorado all day, there are now east-west bands of taller clouds and precipitation developing in southern Wyoming and northern Colorado. The result for the eastern Colorado foothills and plains should be drizzle this evening with occasional rain, mixing with or changing to occasional snow in the foothills. After midnight, drizzle with occasional rain or snow in all areas.  Most areas below 6000 feet will probably have no accumulation. But I think about 1/3 of the area will see up to an inch on grassy surfaces and cars. In the foothills we will probably see 0-3 inches with most areas getting at least a small coating of snow. Roads should be fine.

Temperatures in the low elevations are likely to be around or a little above freezing. Temperatures may also fall into the 30s Friday night with the possibility of patchy frosts, especially in cold spots like river valleys.

Cold, rain & drizzle; then first snow?

6AM, Thursday, September 11, 2014

A very shallow surge of cool air moved through eastern Colorado before sunrise and will likely be strong enough to keep clouds and patchy drizzle in the area today.  Later in the day there should be a colder push of air that deepens the upslope flow into the Front Range.  Moderate intensity snow is falling across northern Wyoming behind that second push.  We should see an increasing coverage of drizzle and some areas of rain by late afternoon.

Snow? The airmass is cold enough to support snow. The question is whether we will have only shallow stratus clouds that tend to produce drizzle and/or freezing drizzle even in cold air. If the clouds develop more vertically then snow is more likely because heavier precipitation helps to cool the atmosphere and ice crystals in tall clouds support snow. Both the current observations and model guidance suggest some east-west bands of deep clouds are likely this evening that will result in rain initially and snow later. In the heavier bands that changeover might occur before midnight. In other areas it could be later in the night, if at all. Although many areas will likely see some snow flakes, accumulations below 6000 feet are likely to range from zero in some areas to about an inch (grassy surfaces) where some of those bands form. Higher elevations may see 1-3 inches.

Temperatures. Friday morning is likely to see temperatures below freezing in the high elevations and around or just above freezing in the lower foothills and plains. After a slow clearing process on Friday, mostly clear skies Friday night should allow more variable low temperatures by Saturday morning in the Denver-Boulder-Fort Collins corridor ranging from the low 30s to the upper 30s. Be prepared for frost.

After the chilly start to Saturday, the weekend is likely to be mainly dry and warmer.

Showery today, much colder late in week

It looks like two cold fronts are headed our way. One today will make things a bit cooler, and one late Thursday will be followed by much colder weather.

 

Expect a mostly cloudy and showery day today and into tonight, maybe even a thunderstorm. The moisture content of the atmosphere is high, so there could be a few local areas that receive some brief heavy rain. By late in the day the winds may be turning mostly to the north behind the first cool front.

 

Wednesday and Thursday should be cooler, but not exceptionally cool (probably highs  of 60s in lower elevations), and a bit drier but still with some clouds and a small chance of afternoon showers. The most interesting weather event of the week should be late Thursday into Friday morning when a strong cold front arrives. Expect low clouds and some rain or drizzle. At this point it looks like the biggest push of precipitation will be through before the coldest part of the air mass arrives. So I don’t expect the first snowflakes or frosts in the lower foothills or plains, but I also cannot rule it out 100%. Temperatures in the lower elevations are most likely to bottom out in the 35-40 range Friday and/or Saturday morning, but I will update later in the week. The upper foothills and mountains have a better chance of some snow and freezing temperatures Thursday night and Friday morning.

 

 

Hot today, then cooler

7:30 AM, Monday, September 3, 2014

 

Today’s record high temperature for Denver is 95, and for Boulder it’s 94.  We will get close to those records, and there is a small chance that we will reach a record.

 

But don’t get used to it. A cold front Thursday morning should keep temperatures on Thursday and Friday about 20 degrees cooler. Dry weather today will give way to a small chance for afternoon thunderstorms Thursday and Friday, especially in the mountains. Overall, not too bad for this time of year. The earliest observed snow in Boulder and Denver occurred on this date in 1961.