wxgeek's weather-Weather Outlook August 17-24-Update 8/20

Update Wed Aug 20

Slight break in precip activity today across the state. Water Vapor imagery shows a drier airmass in place west of the foothills today, so heaviest precip will likely be along and east of the Urban Corridor this afternoon and evening, with still some isolated storms over the mountains and foothills. Storm motion today from the southwest at 10-20 mph. Upper level trough currently over SoCal today with upper ridge centered over the eastern Gulf of Mexico. This pattern allows for a monsoon flow, but best moisture is east of CO today.

Better precip chances will occur across CO on Thursday and Friday, as moisture associated with tropical storm Lowell west of Baja is advected into CO with monsoon flow. In addition, weak upper level disturbance will move across CO aiding in storm development with better instability. Friday looks to be the wetter day at this point, with some areas of heavy rain possible.

By the weekend, a rather vigorous upper trough for August moves into the northern Rockies. This will usher in some cooler temps to CO for the weekend, along with somewhat drier conditions. Some precip will be possible each day, but majority of activity expected to be confined to the mountains.

By early next week, another deep upper trough for August will move into the Great Basin and then the northern and central Rockies. This will bring better precip chances to CO on Monday and Tuesday next week, with snow level possibly lowering to near 12,000 - 13,000 ft Monday night. By Wednesday, upper ridge then builds back into the Great Basin bringing warmer and drier conditions back into CO through next weekend and likely into Labor Day.

Dynamic models suggest the possibility of a tropical wave currently in the Atlantic moving towards Florida or the Gulf of Mexico by mid to late next week. Still too early to tell with any confidence what will transpire, but anyone planning travel to this region should keep an eye on this for next week. More tropical system likely to form off Mexico in the eastern Pacific, as some very warm water exists in this region.

_________________
"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 Mon Aug 18

Upper level ridge currently centered over the 4 Corners area, so flow aloft over CO will be from the west northwest today. There should be enough moisture and instability for storms to pop up over the mountains this afternoon, and then move east into the foothills and plains. Activity will be of the isolated variety, and precip amounts expected to be on the light side for most areas. Some stronger activity will be possible across the far northeast plains this evening.

On Tuesday, upper level ridge is forecast to move into western TX while an upper trough is forecast to move into central CA. This pattern will provide a better monsoon flow from the southwest over CO. In Addition, a tropical depression southwest of the Baja peninsula will provide additional moisture for a good surge of monsoon moisture. Some very heavy rain will be possible Tuesday across portions of AZ and UT as well as western CO. Activity is forecast to spread into the foothills and plains of CO by Tuesday afternoon and evening, so pretty good precip chances for most of the state on Tuesday, with the potential for heavy rain in some areas. Storm motion will be from the southwest on Tuesday at 10-20 mph, so flooding potential will be limited by fairly quick movement.

On Wednesday, upper ridge moves into the lower Mississippi Valley while upper trough moves to near Las Vegas, NV. This will keep a good monsoon flow across CO with good precip potential for most areas of the state. Storm motion once again from the southwest at 10-20 mph. By Thursday, upper trough will move across CO which will enhance precip potential as cooler air aloft creates greater instability, and monsoon moisture will still be present. Thus, some areas of CO could see some very heavy rainfall on Thursday with increased flood potential.

Friday looks to be drier and cooler in the wake of upper trough which will be east of CO, so only looking for isolated showers and thunderstorms mostly along and west of the Divide on Friday. Saturday looks to be very similar to Friday, just isolated storms mostly in the mountains with temps slightly below seasonal norms. By Sunday, an upper trough will approach from the northwest, while upper ridge remains centered over AR, so combination of good monsoon flow with an upper trough approaching will enhance precip activity statewide on Sunday afternoon and evening. This pattern will be present on Monday as well, so expect more widespread precip.

By the middle of next week, looks like monsoon pattern will continue as another tropical system is expected to move up the Baja peninsula. As El Nino has significantly warmed the waters of the eastern Pacific off Mexico, enhanced tropical activity is likely to persist into September, and keep tropical activity to a minimum in the Atlantic basin.

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

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

Bump for 8/21 update