wxgeek's weather-Weather Outlook thru labor day-Update 8/29

Update Thu Aug 29

Another hot and mostly dry day across the state today. Temps already approaching the century mark across the far eastern plains at the noon hour. Pretty limited moisture and instability today, so only expect very isolated showers and thunderstorms from the higher foothills to the mountains. Any precip will be sparse, but storms that do form will be very slow moving from the southwest.

Upper ridge that has dominated weather across the central U.S. this week is weakening slightly and beginning to move back to the west, so now located over OK. Models forecast that this ridge will continue to move back to the west near CO by Friday into the Labor Day weekend and remain anchored near CO through the end of next week. This will translate into continued hot temps across the state, with only isolated afternoon and evening showers and thunderstorms mostly over the higher terrain. Flow aloft becomes more westerly on Saturday, so slightly better precip chances Saturday and Sunday for the foothills as storms that form over the mountains will drift east into the foothills. Plains still expected to mostly hot and dry through next week.

Long range models keep the upper ridge over CO through next weekend, then move it farther west into the Great Basin the following week. This may allow slightly better precip chances for CO, but still isolated type storms. The overall pattern is for temps well above seasonal averages through the middle of September statewide, with lower than average precip. This will begin to bring fire danger levels back up to moderate to high levels by early to mid September, especially as grasses begin to die off and other ground fuel dries out. With the upper ridge position over the Great Basin, it may allow a few weak cold fronts to slide down the back side and impact CO, bringing some temporary relief of hot temps and better precip chances as fronts move through.

For the upcoming winter, ENSO neutral conditions are most likely to prevail, which is what we had last winter. This means there is no clear signal for either La Nina or El Nino conditions, which makes the season much harder to predict with any degree of accuracy. ENSO neutral winters can be a very mixed bag across CO. As we saw last year, we had a very warm and dry Fall and Winter, with a wet and cold Spring. There is no good way to predict how this coming winter snowfall might be. Using past history, ENSO neutral winters tend to have snowfall at or below average for the foothills and Metro Area as well as for the mountains. However, other factors can then outweigh the ENSO contribution, such as the Arctic Oscillation and more seasonal Madden-Julian Oscillations. I will provide a more in depth discussion of the upcoming winter at a later time for those interested.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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Update Tue Aug 27

Very large and strong upper ridge currently centered over southwest MO. This ridge is dominating the weather pattern across the entire U.S. Ridge position is allowing for decent monsoon flow across the Gulf of Mexico and northern Mexico and then northward into CO. However, air aloft is so warm it is limiting the ability for clouds to grow vertically, especially across eastern CO which is closer to the upper ridge. Thus, isolated storms will form over the mountains of CO with some drift east to the foothills and Urban Corridor. Not much activity east of I-25 expected this week. Storm motion will be from the southwest at 5-15 mph. Brief havy rain and small hail is possible with these storms.

Upper ridge is expected to gradually weaken and move slowly westward through Friday, which will move the center close to CO by the end of the week and into the weekend. Thus, above average temps will remain across CO through the weekend, and only isolated shower and thunderstorm activity will persist, with the majority of activity from the foothills west.

By the Labor Day weekend, upper ridge will be centered over CO, so continued above average temps and isolated thunderstorm activity, mostly from the foothills west, with some drift to the adjacent plains by this weekend. Nice weather for anyone wanting to explore the outdoors for the coming weekend and the last major camping weekend of the season. Upper ridge is expected to remain over the central/southern Rockies into the extended period, so expect temps to remain above average with only limited precip through early September. Majority of precip across CO will be from the foothills west, so conditions will begin to dry out quickly on the plains with grasses beginning to die and dry out, so expect increased fire danger from the lower foothills to the plains in September.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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Good monsoon flow remains in place today, and some additional moisture from tropical depression Ivo off the Baja coast will aid in storms developing across the mountains and moving into the foothills and adjacent plains this afternoon and evening. Western CO could see some significant precip today, and NWS has issued a flood watch for many areas west of the Divide. Some storms over the foothills could produce brief heavy rain and frequent lightning along with gusty outflow winds. Storm motion today will be from southwest to northeast at 10-20 mph.

On Monday, upper ridge will remain near the KS/MO border and provide a good monsoon flow across CO. However, moisture from TD Ivo will primarily impact southeast CA, eastern NV, western AZ and UT where serious flash flooding could cause problems on Monday. Some areas in this regions could receive 2-5 inches of rain. Only expect isolated storms west of the Divide across CO on Monday, so temps will be warm and well above seasonal averages for eastern CO.

For the remainder of this week, isolated afternoon and evening storms will be in the picture, forming over the mountains and drifting east across the foothills and adjacent plains. Dry lower levels east of I-25 should minimize precip chances for the plains. Looking towards the Labor Day weekend, models suggest an upper trough will move to our north, which would cool temps back to seasonal levels or slightly below, and increase precip chances over the coming weekend as a cold front will drag across the state. The following week, upper ridge is expected to rebuild over the Inter-Mountain West, which would create warm and mostly dry conditions for CO.

So far this month. I have recorded 2.25 inches of rain on Conifer Mountain, which is still below our average of 2.75 inches for the month. It is however, well above last year in August when we only received 1.75 inches of rain. The North American Monsoon is still in full swing, and looks to last into early September.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

Bump for 8/27 update

Bump for 8/29 update