wxgeek's weather-Upcoming storm Update Wed May 11

Update Wed May 11

Upper low currently over southwest CO and is forecast to slowly move into east central CO by Thu morning. This track will keep precip going all day today, tonight and into Thursday. Upper level flow currently southeast and will turn to a more easterly to northeasterly flow this afternoon and tonight, which is even more favorable for snow production. With already 3-6 inches of snow above 7000 ft, snow totals need to be incraesed for the storm. I would expect an additional 3-7 inches between 6 am this morning and 6 pm Thursday above 7000 ft. Snow level currently between 6000-7000 ft and will rise slightly during the day today to 6500-7500 ft, but lower again tonight to 6000-7000 ft with snow possible all the way down to Plains level overnight tonight. As system moves east on Thjursday, precip will move farther east as well with heaviest precip being out on the far eastern Plains after noon on Thursday, although some lingering flurries still possible through 6 pm Thursday for the foothills. Roads will likely remain slushy today and this evening above 7000-7500 ft, and become more snow packed overnight tonight, so Thursday morning commute likely to be slick and slow along 285. I expect the current Winter Weather Advisory that is in effect for the foothills until 6 pm Wednesday will be extended into Thursday.

Warmer and drier weather still on tap for Friday through Sunday.

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Update Tue May 10

Models continue to enhance our upcoming storm. Upper level low currently over northwest AZ will move into the 4 corners region this evening, and then slowly trek across southern CO Wed and near the CO/KS/NE border area by Thursday morning. The slower movement will help to enhance our precipitation totals from this system. Most of eastern CO from the foothills to the Plains should receive between 0.50 and 1.00 inches of liquid equivalent precipitation from this system, which will really help the ground to soak up some moisture.

Timing looks like this. Precipitation should begin between 9 pm and midnight tonight, with precip becoming heavy overnight. Precip will continue all day on Wednesday and into Wednesday night. Precip should end over the foothills by Thursday morning, but could persist east of I-25 into Thursday afternoon. Snow level will begin around 10,000 ft this evening, lowering to 8000-9000 ft by midnight, and down to 7000-8000 ft by Wednesday morning. Snow level will rise to 8000-9000 ft during the day on Wednesday. Accumulations: 1-2 inches below 8000 ft, 2-4 inches between 8000-9000 ft, and 3-6 inches above 9000 ft for this system. I still think much of the snow will melt on pavement below 9000 ft, but some roads could have slick spots Wednesday morning especially above 8000 ft. There will also be a fair amount on instability with this system, which could mean isolated thunderstorms, and thundersnow at times. Snowfall rates of 1-2 inches per hour are possible in these convective showers.

There will also be upslope flow up to about 14,000 ft starting tonight and persistsing trhough Wednesady night, so the foothills will be shrouded in clouds and fog along with the precipitation, which will reduce visbiility to very low levels at times, so the Wednesday commute will likely be a slow one along 285. Broad precip across the region will also slow traffic on Metro area roads with rain, which could be heavy at times.

Because this system will be slow to exit the region, warmer temps will be delayed until Friday, with Thursday still being fairly cool and showery, especially across the far eastern Plains. Friday through Sunday then looks warmer with near to slightly above seasonal norm temps, and a chance for afternoon and evening showers and thunderstorms.

Long Range models indicate more chances for precipitation later next week and into next weekend.

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Update Mon May 9

Another warm and breezy day today, so a difficult day for fire fighters once again. Southwest winds of 20-45 mph will continue into this evening. Some high level mosture is making it's way across the state, but low levels remain quite dry with RH values in the 5-15% range, hence the Red Flag Warning for today. Models remain in good agreement on our upcoming storm. The upper trough will split today, and after some precipitation in western CO today, conditions will become mostly dry and breezy on Tuesday across the state, although temps should be cooler and higher RH values, so not as bad for fire fighters. Models bring the southern branch of the trough into the 4 corners region Tuesday afternoon and close it off while it treks across southern CO on Wednesday. This will bring precipitation across most of central and eastern CO from Tuesday night into Wednesday evening. For the foothills, precip should begin Tuesday night around midnight and continue all day on Wednesday ending Wednesday evening. Upslope flow will develop and keep clouds and fog along with precip against the foothills from Tuesday night inot Wednesday evening. Model QPF (Quantitative Precipitation Forecast) amounts are in the half inch of water equivalent range for this event, so this system should provide a nice soaking for the foothills and adjacent Plains. Snow level will be in the 7500-8500 ft range Tuesday night into Wednesday morning, rising to the 8000-9000 ft range during the day on Wednesday. Snow amounts likely to be in the 1-2 inch range below 8000 ft, and 2-4 inches possible above 8000 ft. With recent warm temps, initial snow likely to melt on asphalt, and with temps not too far below freezing during the day on Wednesday, roads probably will remain just wet below 9000 ft, but some slush or snow may be possible, so be careful while driving from Tuesday night into Wednesday evening as slick spots could develop, especially on less traveled and dirt roads.This moisture is very welcome and will hopefully help our very slow "green up" this spring.

The remainder of the week from Thursday through Sunday looks warmer with near to slightly above seasonal norm temps, and chances for afternoon and evening showers and thunderstroms from Friday through Sunday, especially over higher terrain. After this week, snow becomes much less likely while afternoon showers and thunderstorms will become much more common. With the return of our thunderstorm season, lightning will become more frequent, so extra caution will be required when outside during thunderstroms, as well as the threat of lightning induced fires while our ground is still so dry.

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Tough couple of days for fire fighters. Warm temps coupled with very low hunidities and strong southwest winds will make fire fighting difficult today and Monday. Soutwest winds today will increase this afternoon into tonight with speeds in the 20-45 mph range. RH recovery overnight tonight will be fairly non-existent, so fire growth will continue overnight. Monday will be another diffuclt day with southwest winds of 20-40 mph and single digit RH.

A significant change to our current weather pattern will begin to occur on Tuesday. Upper trough currently in the Great Basin will move east and begin to affect CO late on Monday, with precip developing west of the Divide. Snow level will remain above 10,000 ft on Monday. Models indicate the upper trough will split into two pieces of energy, with a northern branch that will move into the Dakotas, and southern branch that will eventually affect CO. Cold front associated with the northern branch will move across CO Monday night which will bring cooler temps and higher RH values to the entire state on Tuesday. Southern branch of the trough will move across the 4 corners region on Tuesday and across southern CO on Wednesday. This will bring increased chances for precip across the foothills and Urban Corridor beginning Tuesday evening, and continue into Wednesday evening. Snow level could drop below 8000 ft Tuesday night into Wednesday morning, so some accumulating snow possible above 8000 ft, although amounts look to be on the light side, but any moisture is very appreciated at this point.

Long range models then indicate a return to a warm and dry regime from Thursday through next weekend, so a return to higher fire danger once again.

Bump for May 10 update

Bump for May 11 update