wxgeek's weather-Weather Outlook May 13-26-Update 5/25

Update Sun May 25

I would like to fist take this opportunity to thank everyone who has served or is serving in our armed forces. Your sacrifice is greatly appreciated by all of us that enjoy the freedoms in our wonderful country.

Upper low has now moved in southwest CO this morning, creating a southeast to easterly flow aloft over eastern CO today. This has created some surface upslope flow as well, so low clouds have pushed into foothill areas. More chances today for showers and thunderstorms, especially along and west of I-25. Foothills could see some heavy showers as upslope flow aids in mositure and lift for storms. Mountains will also see widespread activity. Precip could again presist into evening and nighttime hours. Localized flooding also possible in areas of heavy showers and thunderstorms. Snow will be possible mostly above 12,000 ft but could lower to 10,000 ft in heavier showers.

Upper low is forecast to move slowly across southern CO and be located in southeast CO Monday. This will decrease precip chances for much of CO on Monday, except across southeast CO where precip chances will remain high. Afternoon and evening showers and thunderstorms still possible Monday from the Divide east, but coverage and amounts expected to be less than past several days.

Things finally begin to dry out and warm up Tuesday into Thursday. Models then suggest better precip chances will be possible across the state Friday into Sunday.

_________________
"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 Sat May 24

Another round of afternoon and evening showers and thunderstorms wili occur across most of CO yet again today. NWS has issued a Flash Flood Watch for much of the Urban Corridor and foothills from 1 pm through 8 pm today as ground is saturated most areas, so any additional precip will now run off. Most areas will see from, 0.25 to 1.0 inches of rain today, but localized amounts of 2-3 inches possible in heavy storms. Storms will once again move from south to north at 5-15 mph today. With slower movement comes flood potential along with small hail. Some areas of CO have received up to 4 inches of rain since Tuesday, so any additional precip becomes a problem. Heaviest precip today will be from I-25 west back into the mountains, where NWS has issued a Winter Storm Watch. I believe this was only issued because of the holiday weekend to alert travelers into the back country of snow potential. Snow level looks to remain around 12,000 ft today, but could lower to 10,000 ft in heavy showers. Storms will persist into the evening and nighttime hours.

Our slow moving upper low today is centered in central AZ, and is expected to move into the 4 Corners region Sunday, then southeast CO Monday. Each day should see slightly less coverage and precip amounts, except in the mountains where higher amounts expected today and Sunday. Monday looks to be the driest day in the past 6, but isolated afternoon and evening storms still will be posisble, as there is a lot of low level moisture across the state, so will not take much to fire new storms. Streams and rivers already on the rise, so any additional precip could push levels to near or above flood stages next 2 days, so residents in prone areas should remain alert.

We finally get some relief next week, with warmer temps and only isolated afternoon and evening showers and thunderstorms. Next surge of moisture looks to be late next week into the weekend.

_________________
"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 Fri May 23

Yet another round of showers and thunderstorms on tap today. Upper low currently spinning over southwest AZ and will only move to northeast AZ by Saturday. Flow aloft remains southerly, so storm motion today from south to north, maybe slightly east at 5-15 mph. Denver sounding shows precipitable water as high as on Wednesday, but atmosphere is not as unstable, so expect mostly heavy rain and some small hail today in heavier thunderstorms. More clouds today, so temps will not be as warm as Thursday. Focus of heavy rain today will likely be in the foothills, but Urban Corridor and plains will see heavy showers as well. Mountains begin to get precip this evening, and then focus of heavy precip shifts west into the mountains for the weekend.

Upper low forecast to move slower now, so will hang around through Memorial Day across northeast NM, hence afternoon and evening shower and thunderstorm activity will persist into Memorial Day. Models indicate less moisture overall for the weekend, but mountains will squeeze out all possible moisture, while we should see slightly less precip in the foothills and plains over the weekend. Still cannot rule out localized flooding in heavy storms for all areas of COI through Memorial Day. Mountain areas will see significant stream and river rises this weekend, so anyone spending time in the High Country should be aware of stream and rivers flows.

Despite the weather, hope everyone is able to enjoy the first holiday weekend of the year. The good news is fire danger is way down across the state, which is nice to see this time of year. Much different across parts of the West and Southwest.

Time to go chase a little white ball around. I always find the legend of golf fascinating, making it 18 holes as that was the number of holes it took to finish off a fifth of Scotch.

_________________
"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 Thu May 22

Round 3 of severe weather on tap for today. Pretty wild weather day yesterday, with tornadoes, large hail and damaging winds causing significant damage from the foothills to the plains. Latest data suggests severe weather chances will not be as high as Wednesday, but will still be present. Threat today will be mostly large hail, strong winds and heavy rainfall, tornado chances are lower than Wednesday, but weak tornadoes not out of the question. Flow aloft is south southwest today and weaker, so storm motion more from south to north, and at 10-15 mph. Slower storm motion provides greater flood potential and higher precip amounts. Storms expected to develop along the foothills early afternoon and move into the Urban Corridor and plains later in the afternoon and evening. Models showing high precip potential across south central and southeast CO today, as well as good precip potential for foothills and Urban Corridor. Storms could persist into nighttime hours once again, especially on the plains. Hail to 1.5 inches possible, and winds to 60 mph also possible.

Upper level low currently over southern CA today, and still expected to move slowly into AZ Friday, near the 4 Corners Saturday and over southern CO Sunday. Friday still looks to be the wettest day across the state overall, especially foothills and Urban Corridor, but severe threat very low, just small hail and heavy rain possible. Storms may start early Friday as plume of moisture moves up from Mexico and NM, and then persist late into the night. As upper low moves closer to CO this weekend, precip focus shifts to the mountains. Foothills and plains still likely to see precip, but highest amounts expected along and west of the Divide this weekend. Snow level remains above 12,000 ft, so heavy runoff expected in streams and rivers across much of CO. Conditions expected to dry out some on Monday east of the Divide. This pattern will persist into next week with warmer temps and only isolated afternoon and evening showers and thunderstorms expected.

_________________
"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 May 21

Get ready for round 2 of severe weather across eastern CO today. Moist and unstable airmass in place over eastern CO today, although stratus related to outlfow from yesterdays convection may delay the onset of storms a bit today. Convective temp from Denver sounding is 66 deg F today, so that is the surface temp needed to initiate convection, and should be reached around Noon today. Storms will develop initially over the foothills and mountains east of the Divide, then spread northeast into the Urban Corridor and eventually the plains. Good vertical shear profile again today to support rotating supercells that will likely spawn tornadoes. Best chance for severe thunderstorms will be east of I-25, but some could form in the foothills as well. Hail up to 2 inches in diameter, winds to 60 mph, heavy rain and tornadoes all possible today across much of eastern CO. Residents should remain aware of possible severe weather conditions and be prepared to take appropriate actions as needed. Today's storms will move in a northeasterly direction, although once storms become severe, they typically take more of a right turn motion, so could head due east. Storm motions of 20-30 mph likely, so fairly fast moving storms which will limit flood potential, although localized flooding in heavy storms definitely possible today. Storms will move onto the plains this evening and may persist into overnight hours.

Expect another repeat on Thursday as the upper level pattern remains nearly stationary with upper level low moving into the lower Colorado River Basin over the CA/AZ border region. Severe weather threat will again be present across much of eastern CO, and heavy rain possible. Storm motion remains northeasterly Thursday although slightly slower, so greater flood potential and precip begins to move into the mountains as well.

By Friday, upper low expected to move into AZ, so a more southerly flow aloft over CO. Models suggest Friday to have the greatest flood potential for foothills and Urban Corridor with very heavy rain possible across much of the state. Storms will move in a northerly direction, but slower, at 5-15 mph. Severe weather threat lower on Friday, but flood potential becomes higher as up to 2 inches of rain possible in some areas over 24 hour period. Storms could persist into overnight hours, especially over mountains and plains.

By the weekend, upper low expected to move into NM on Saturday, and southeast CO Sunday. Showers and thunderstorms likely to develop each day, and more heavy rainfall is possible. The focus will shift westward into the mountains for heaviest rain, but foothills and Urban Corridor could still see isolated heavy rainfall. Flood potential will also shift to the mountains, although runoff into streams and rivers east of the Divide could become an issue over the weekend as snow melt and runoff combine.

Memorial Day we should begin to see some drying, with only isolated afternoon and evening showers and thunderstorms as upper low finally moves east of CO. Streams and rivers may remain very high into Monday from weekend runoff. Overall, a pretty soggy period leading into Memorial Day. Not the best weather to kick off the camping season, but great weather to keep fire danger low. Some areas of CO could see 3-5 inches of rain from today into Monday, with most areas seeing 0.5 to 2.0 inches of rain. Certainly enough to create localized flooding concerns.

Most of next week looks warm, with afternoon and evening shower and thunderstorm chances. Pretty typical summer type weather pattern across CO as upper ridge builds over CO and upper trough settles along the West Coast. Temps likely to be above seasonal norms next week.

_________________
"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 May 20

Felt a lot like summer this morning, warm temps and relatively high RH values with dew points in the 45-55 deg F range along the Front Range and plains. Upper level low currently centered over central CA. This upper low will move very slowly over the next 5 days, into southern NV Wednesday, southeast CA Thursday, southwest AZ Friday, the AZ/NM border Saturday, southeast CO Sunday and finally the OK panhandle Memorial Day. For much of the next 5 days, we will see plenty of low level moisture, a fairly unstable atmosphere, and warm temps. This is a fine combination to fuel afternoon and evening showers and thunderstorms. We will also have a decent vertical shear profile today and Wednesday, which will lead to good chances for severe thunderstorms across much of eastern CO. The focus today looks to be north of I-70 and east of I-25. Larger potential area on Wednesday, with pretty much all areas east of I-25. Potential for damaging winds, hail up to 2 inches in diameter, heavy rainfall and isolated tornadoes. Storm motion today and Wednesday will be from the southwest to northeast at 20-30 mph, so fairly fast moving storms, which will limit flooding potential, but favors rotating supercell development with southeast surface winds and southwest winds aloft.

So, for the day to day forecast, today showers and thunderstorms possible from the Divide east, with severe thunderstorm potential across northeast CO (I-70 north and I-25 east). Storms may linger through midnight over the plains. For Wednesday, better chances from the Divide east for showers and thunderstorms, with increased chances for severe thunderstorms and tornadoes east of I-25. Storms will die down after midnight. For Thursday, chances statewide for afternoon and evening showers and thunderstorms. Flow aloft becomes more southerly, so severe potential decreases, but storm motions slows, so flood potential increases. Friday looks to be the day with the highest precip chances statewide and highest rainfall potential. Storms could start late morning in the mountains and foothills, move east and persist into late evening and nighttime hours. Severe potential pretty low, but flood potential increases Friday. Snow level remains above 12,000 ft during this period, so rain may melt a fair amount of snow below 12,000 ft to create some high runoff potential. Saturday and Sunday both look to have good potential for afternoon and evening showers and thunderstorms statewide, and this trend looks to continue into Memorial Day. Things could become pretty soggy by Memorial Day. Models generally outputting 0.75 to 2.0 inches of rain for eastern CO, with up to 3 inches possible in mountain areas between today and Monday. I do not think this is enough to cause widespread flooding like we saw last September, but we could certainly see localized flooding where storms drop a lot of rain in a short period of time. We will also likely see small streams and rivers rise significantly during this time due to snow melt and local runoff. Residents in flood prone areas should remain alert through Memorial Day for possible evacuations. The good news is that fire danger should remain pretty low through Memorial Day with the rainfall and higher RH values in the foothills. Some areas of southern CO may continue to see high fire danger.

For those asking whether events like this and last September are becoming more common, my initial reaction is yes, they are. The Balkans just saw record flooding last week, and areas of Italy and the UK earlier this year. All these events have a common thread, a very slow moving upper level lows. We refer to these usually as cutoff upper lows, meaning they are cut off from the main atmospheric flow. An interesting research paper recently was written that these slow moving upper lows are becoming more common as the atmosphere warms. As there is less contrast between a cold polar region and tropical region, the flow aloft becomes less organized, meaning slower jetstream speeds and more cutoff lows. My observations would tend to support this theory recently. The paper also claims more stubborn upper ridges will be present, which we have also seen, like over CA and the Desert Southwest the past 2-5 years. I am not laying claim as to why the atmosphere is warming, there are likely many reasons for that, just presenting some effects associated with a warming planet. My personal belief is we will continue to see more extreme weather as our planet warms, so more intense flooding, more extreme droughts, more severe tropical storms etc... More heat means more energy and water vapor for the atmosphere to work with. This will likely continue until something triggers a cooling event on our planet. As we are still currently in an ice age (Quaternary Ice Age) that began about 2.5 million years ago, we will eventually go back into a glacial period. We are currently in an inter-glacial warming period of the current ice age. So a nice time to be on this planet. Not sure how the current human race would do during another glacial period. The last glacial period about 10,000 years ago saw an ice sheet 3000-5000 ft thick creep down into the northern U.S. Hard to imagine life as we know it today continuing in that climate. Yet, I am pretty certain our planet will experience that many more times in years to come. I am just thankful to have lived during a very nice climate on this planet.

_________________
"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 Sun May 18

Warm temps across CO today, along with some mid and high clouds and gusty winds. Winds mostly southwest from western CO to the foothills, then southerly along the Urban Corridor and plains. Winds speeds in the 15-35 mph range, and should remain gusty tonight into Monday evening. This has prompted NWS to issue a Red Flag Warning today and Monday across southeast CO. A few showers have popped up across northeast CO, mostly north of I-70 and east of I-25.

Expect a repeat of today for Monday and Tuesday with temps well above seasonal norms and gusty west to south winds. No precip expected either day.

Upper level low will move down the CA coast Monday into Tuesday, then settle into the Great Basin Wednesday before moving into the Desert Southwest Thursday through Saturday, then into NM Sunday and Monday. This slow movement will import moisture into CO Wednesday through Memorial Day. Latest models however, do not produce the high precip amounts earlier models had. As events get closer, this now looks more reasonable, bringing isolated showers and thunderstorms to the eastern plains Wednesday, then bring more widespread showers to much of CO Thursday into Memorial Day. Some storms could become severe, and produce 0.5 to 1.0 inches of precip, but it currently does not look like any widespread flooding will occur. This could change, but right now just looks like isolated to scattered showers and thunderstorms late this week into the Memorial Day weekend. Snow level should remain above 12,000 ft. Temps also look to remain at or slightly above seasonal norms through Memorial Day. Afternoon cloud cover will keep temps from getting too warm most days.

Longer range models keep temps warm and chances for afternoon and evening showers and thunderstorms into next week. With thunderstorms will come lightning, and the potential for fire starts. Green up has occurred in most areas, but forest ground remains relatively dry with needle and dead leaf buildup, so any fire starts could move quickly. Hopefully the opening of camping season this week will see campers remain responsible with camp fires.

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

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

---

Update Fri May 16

Showers and a few isolated thunderstorms moving across CO this afternoon, and will likely persist into the evening and possibly overnight in some areas. Long fetch of moisture present in northwest flow back to ID that will move across CO. Snow level above 10,000 ft today. Warmer temps and more afternoon and evening showers and isolated thunderstorms on tap for Saturday, with snow level above 12,000 ft.

By Sunday, flow aloft turns to southwesterly, which will increase temps and dry things out, so no precip expected statewide on Sunday with temps 10-15 degrees above seasonal norms. Same situation for Monday and Tuesday, dry and warm. Some gusty southwesterly winds may develop Sunday night into Monday night, especially across the foothills. this would normally create high fire danger, but with recent snow fire danger should remain low to moderate in the foothills, higher over southeast CO.

Models remain consistent in dropping an upper level low from the Pacific Northwest into the Great Basin by early next week. This will begin to impact CO weather starting Wednesday. Upper trough is expected to linger over the Desert Southwest and central Rockies through Memorial Day, which means increased precip chances from Wednesday through Memorial Day. Models suggest heaviest precip would be towards the end of next week into early next weekend. Situation will also be conducive to thunderstorms and possibly severe thunderstorms east of I-25 next week. Still too ealry to pinpoint precip amounts for specific areas, but looks like a good bet portions of CO will receive abundant precip next week. Models then suggest warmer and drier conditions after Memorial Day.

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

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

---

Update Wed May 14

After a mostly sunny start to the day, clouds now increasing and showers beginning to develop mostly along and east of the Divide. Relatively moist and unstable northerly flow aloft over CO today, so expect showers to increase this afternoon into this evening, then dissipate after sunset. Snow level today looks to be 7000-8000 ft, so another dusting to an inch or so of snow possible in the foothills and mountains.

Northwest flow aloft remains over CO Thursday and Friday as upper ridge builds towards CO from the west. Result will be warmer temps each day, but better chances for showers and isolated thunderstorms each day as well. Best chances will be from the Divide to the Urban Corridor. Snow level looks to rise to 9000-10,000 ft Thursday, then above 10,000 ft Friday. Friday will have the highest precip amount potential with some areas receiving up to 0.50 inches in heavier showers.

For the weekend, temps will be above seasonal norms, with Sunday being the warmer day. Only a slight chance for showers Saturday afternoon/evening, focused mainly over higher terrain. Sunday looks dry statewide and warm, with temps 5-15 degrees above seasonal norms as flow aloft turns southwesterly as upper trough moves into the Pacific Northwest.

For next week, Monday and Tuesday look dry and warm as well. Upper trough moves into the Great Basin early next week, and will begin to impact CO weather mid to late next week. By Wednesday next week, upper trough becomes nearly stationary over the Great Basin, keeping flow aloft over CO from the south southwest. With upper ridge over the Gulf of Mexico, we begin to see a very early version of our Monsoon flow. I am beginning to become a little worried about flood potential for next week. Models indicate that up to 3 inches of precip may fall over portions of CO from Wednesday into next Saturday as upper trough remains nearly stationary, which is similar to the September pattern we had last year. Not as much moisture available this time of year, but CO could still see some pretty heavy rainfall, which combined with abundant snowpack could cause streams and rivers to rise rapidly next week, mostly east of the Divide. Snow level looks to be between 10,000 and 12,000 ft next week, so melting of significant snowpack may not be an issue, but residents in flood prone areas should stay tuned to future forecasts for next week.

Latest models indicate conditions may clear up some next Sunday and Monday for Memorial Day weekend, but longer range models bring another upper trough into the Great basin later that week, for more precip chances.

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

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

---

Gradual warming and clearing trend today across the state, although temps will remain some 20 degrees below seasonal norms today. Isolated showers will be possible today, mostly over the High Country, but foothills and plains could see a stray shower or two. Snow level today around 6000-7000 ft, but little to no accumulation expected. The warming trend will continue into this weekend as upper ridge currently along the West Coast moves slowly towards the Rocky Mountains. Northerly flow aloft will remain into Friday, then switch to southwesterly flow aloft this weekend as upper ridge moves east and an upper trough moves into the Great Basin. Afternoon and evening showers will be possible each day this week, but probabilities remain low today and Wednesday. Chances increase Thursday into Saturday, as temps warm, more heating available to aid in development. Snow level Wednesday rises to around 8000 ft, then to around 10,000 ft Thursday, and will remain above 10,000 ft Friday and Saturday. Best chances for precip in the foothills looks to be Friday. Isolated thunderstorms will also be possible Friday and Saturday. Temps should be back to seasonal norms by Friday, then above seasonal norms Saturday and Sunday.

Sunday looks warm and dry, and Monday should be very similar. By Tuesday, impacts from upper trough in the Great Basin will begin to be felt in CO. Shower chances return mostly along and west of the Divide Tuesday, then much better chances for precip statewide next Wednesday into Memorial Day as upper trough lingers over the Rockies. It could be a rather soggy Memorial Day weekend, but snow level looks to remain above 10,000 ft. Models are not very good at details this far out, so just using the pattern to suggest precip chances increase late next week into next weekend. Specific details of where and how much are yet to be revealed.

The good news from my perspective is that May has been, and looks to continue to be a rather wet month. Many areas of Co will have received over 2 inches of liquid precipitation, which has greatly helped in keeping fire danger at low levels. Now we move into June, which is historically the worst month of the year for wildfires in CO. Hopefully Mother Nature can continue the wet trend into June.

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

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

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