wxgeek's weather-Wet/ Cooler Weather Wednesday through Friday-Update 10/8

Update Thu Oct 9

Soggy day ahead for most of CO. Precip associated with upper level trough that contains moisture from former tropical storm Simon is spreading into CO this morning. Upper level circulation is currently near the 4 Corners region and is forecast to slowly move east across CO today into Friday morning. This feature will create upslope flow over eastern CO today into Friday that will enhance precip. Rain is expected to become heavy at times this afternoon into tonight before tapering off early Friday. Embedded thunderstorms will be possible this afternoon and evening as well. Models still suggesting precip amounts in the foothills will be in the 0.5 to 1.5 inch range, with some amounts from 2-3 inches possible. Highest precip amounts still anticipated south of I-70 and east of the Divide, especially over the southern foothills and Palmer Divide. NWS has issued a Winter Weather Advisory for the southwest and central mountains extending into the Front Range mountains for 3-7 inches of snow above 10,000 ft. Flash Flood Watch is also in effect for Palmer Divide and south along the I-25 corridor. Winter Storm Warning is in effect for Sangre de Cristo mountains above 10,000 ft for 8-14 inches of snow.

In essence, lots of rain and snow at higher elevations today into Friday morning. Snow level expected to remain at or above 10,000 ft, but could see some snow down to 9000 ft tonight, although accumulations not expected below 10,000 ft. Small stream flooding and debris flows will be possible in areas that receive heaviest rainfall, especially in former burn scars. Upslope flow will also create foggy conditions in the foothills today into Friday, so slower driving speeds will be likely, along with standing water on many roads today into Friday. Travel across higher mountain passes will encounter winter driving conditions.

Conditions will improve through the day on Friday, although foggy conditions in the foothills may persist, as well as showers through Friday afternoon. Temps will remain well below seasonal norms today and Friday.

By Saturday, system will move east and a return to dry and warmer conditions will exist. Temps back to seasonal norms under mostly sunny skies statewide on Saturday. Sunday will start out nice, but a fast moving system from the northwest will bring increasing clouds and a chance for precip by Sunday afternoon. System will be a colder system so temps back below seasonal norms by Sunday afternoon. Precip moves into the northern mountains first and spreads east into the foothills and plains by afternoon and evening. Precip amounts expected to be on the light side with heaviest amounts north of I-70. Snow level will begin at 8000-9000 ft Sunday afternoon lowering to 6500-7500 ft by Sunday evening and night. For the foothills, not much more than a dusting expected, but it is possible some areas could see 1-2 inches of snow by Sunday night.

Next week still looking dry and mild statewide with temps above seasonal norms.

_________________
"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 Wed Oct 8

Another beautiful day across the state today, but change is on the way. Upper level trough that contains moisture from former tropical storm Simon is located along the CA/AZ border currently. Precip is mostly confined to AZ and NM today, with some heavy rain across portions of AZ. Models generally in good agreement, but as usual have their differences. Models bring precip into southwest CO tonight and slowly spread precip east into eastern CO during the day on Thursday. Upper level trough will be near the 4 Corners region Thursday morning, and High pressure from the Plains will create upslope flow at the surface and aloft over eastern CO during the day on Thursday into Thursday night. This will enhance precip, especially along the foothills and Palmer Divide. Models suggest heaviest precip will be south of I-70 and east of the Divide. Precip amounts currently range from 0.25 to 0.50 inches for most areas east of the Divide with up to 2-3 inches in some areas. Embedded thunderstorms will be present into Thursday evening as well. Heaviest precip for the foothills looks to be from Thursday afternoon into Friday morning. Precip is expected to taper off Friday turning to isolated showers by Friday afternoon. With upslope flow, fog and low visibilities will be likely in the foothills from Thursday afternoon into Friday morning. Heavy rain could also create localized flash flooding and debris flows in areas with heaviest rain. Rain will also likely slow the Thursday evening and Friday morning commutes. Snow level is expected to remain above 10,000 ft, so snow should not impact most foothill areas, just higher mountain terrain. Temps will remain below seasonal norms Thursday and Friday due to upslope flow and cloud cover.

By Saturday, conditions dry out and temps warm back to or above seasonal norms. GFS has now come into agreement with ECMWF model for Sunday, which means cooler temps and a chance for afternoon showers as upper trough moves across CO from the northwest. Snow level expected to be 8000-9000 ft during the afternoon on Sunday, but could drop to 7000 ft Sunday night. Any accumulation expected to be light for the foothills, maybe 1-2 inches in the mountains.

Next week continues to look dry and mild from Monday through Saturday, with temps above seasonal norms. Next chance for precip across CO would be next Sunday/Monday as an upper trough passes through. Beyond that, CO still looking mostly dry and mild into late October.

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

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

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Models are coming into good agreement on a wetter pattern for CO from Wednesday through Friday. Moisture from remnants of tropical storm Simon is bringing precip into SoCal, southern NV and western AZ today. Combined with this, a weak and slow moving upper level trough currently over CA is forecast to pick up the moisture from Simon and move slowly east the next 48-72 hours. Models now bring precip into eastern UT and western CO Wednesday, then move precip into eastern CO Wednesday night into Friday afternoon. Rain, which could be heavy at times with embedded thunderstorms, will move into western CO Wednesday, then spread east Wednesday night into the foothills and Urban Corridor. Heaviest precip for eastern CO looks to be Thursday into Thursday night where foothills and eastern plains could receive abundant precip Thursday afternoon into Thursday night, with showers persisting into Friday afternoon. Rainfall amounts could be quite high for October in CO with general amounts of 0.25 to 0.50 inches across much of CO, while some areas could see 0.75 to 1.50 inches of rain from Wednesday into Friday afternoon. This could cause some flash flooding and stream rises in areas with heavier amounts. Snow level looks to remain above 10,000 ft, so only higher mountain passes will be impacted by snow from this event. Temps will be closer to seasonal norms during the Wednesday to Friday period.

Upper trough moves east of CO by Friday night, so drier and warmer weather is on tap for the weekend, with temps warming back above seasonal norms.

For next week, GFS and ECMWF are not in good agreement. GFS keeps CO dry and mild for all of next week, while the Euro model would be much cooler Monday and Tuesday with a chance for some light precip. Both models agree mid to late next week will be dry and mild statewide. Longer range models keep a mostly dry and mild pattern over CO through at least mid October and possibly into late October as upper ridge remains over the inter-mountain region. No major winter storms on the horizon at this point. Next ENSO advisory is scheduled for October 9, so will have more information on the progress of our building El Nino after that.

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

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

Bump for 10/8 Update

Bump for 10/9 Update