Chinook Posted May 23, 2015 Author Share Posted May 23, 2015 Tornado reported at La Junta. Link to comment Share on other sites More sharing options...
BlizzardWx Posted May 25, 2015 Share Posted May 25, 2015 Had a nice thunderstorm last night, still looking at more rain through Friday or so. I am looking forward to some warm ridging that will follow so I can finally go hiking again. Link to comment Share on other sites More sharing options...
Drz1111 Posted May 26, 2015 Share Posted May 26, 2015 I've often noticed how storms will follow the South Platte River valley and wonder if, over the long term, the rivers were shaped by a long-running weather pattern or the weather pattern is shaped by the geography. Interesting question, and an area of active research. In the case you mentioned above it's pretty clear that the weather pattern is shaped by the geography, but more broadly there is strong evidence that there is a positive feedback loop between elevation and storm development. Think of it this way - you get an initial area of uplift. The windward side of that uplift gets enhanced precipitation. That leads to enhanced erosion on the windward side of the range. That leads to enhanced isostatic uplift on that side of the range. But the erosion is not uniform - it's concentrated in deep gorges (in areas of significant uplift). So the higher peaks - which haven't yet meaningfully eroded - actually get higher. That enhances orographic precipitation in windward areas. That enhances erosion in the gorges, which unloads the deeper crust, leading to more isostatic uplift and even higher elevations, etc. Uplift in the western US is very complex, so the contribution of precip to uplift is not nearly this simple or obvious, but the above mechanism is generally thought to explain the highest elevations of the Himalayas (which otherwise wouldn't be meaningfully higher than the Tibetan plateau, which sit in their lee/ rain shadow during the monsoon) and probably also maintains the Appalachians, even though with hundreds of millions of years of erosion you might have expected them to have long since disappeared. It also clearly has some cool impacts on the topography of the west coast of South America which are, to my knowledge, still poorly understood. I.e., one of the reasons the Andes in Peru/Bolivia/Northern Chile manifests as rolling, ultra-high plateau as opposed to a jagged range is because the Pacific side sees so little precipitation that erosion rates are remarkably low for such large relief, and so the topographic expression doesn't really look like areas of significant crustal thickening anywhere else in the world (except for Tibet, which looks that way because the Himalayas are taking all the rain/erosion/isostatic effects and leaving a dry/flat/high plateau in their lee, per the above). Link to comment Share on other sites More sharing options...
BlizzardWx Posted May 27, 2015 Share Posted May 27, 2015 Up to 3.95" on the month with more to come at my house. Wettest month in my 5 years here I think. Link to comment Share on other sites More sharing options...
frontranger8 Posted May 28, 2015 Share Posted May 28, 2015 Over 6" on the month here. Wet but not close to Sep 2013 (14"), and not quite on the level of the 8.5" I saw in July 2011. However, the 24 of 27 days this month with rain beats anything I've seen. Link to comment Share on other sites More sharing options...
Chinook Posted May 28, 2015 Author Share Posted May 28, 2015 Over 6" on the month here. Wet but not close to Sep 2013 (14"), and not quite on the level of the 8.5" I saw in July 2011. However, the 24 of 27 days this month with rain beats anything I've seen. Fort Collins has close to 5.8" or 5.9" this month, which is close to the 6.09" the we got in September 2013 (the wettest month that I have lived here.) Link to comment Share on other sites More sharing options...
Chinook Posted May 29, 2015 Author Share Posted May 29, 2015 It has been 4 to 6 degrees F below normal here for the month. That is pretty impressive for a non-winter month. Link to comment Share on other sites More sharing options...
Chinook Posted June 2, 2015 Author Share Posted June 2, 2015 Fort Collins got 6.34" of precipitation in May (261% of normal.) I believe this is one of the wettest months that I have lived though in my lifetime. Today, finally the warm, dry layer is mixing away the surface moisture, and we are getting temperatures 84-91 in the area. Dew points have dropped to the lower 40's and upper 30's. (dew points fluctuating between 32-41 in town) Link to comment Share on other sites More sharing options...
mayjawintastawm Posted June 3, 2015 Share Posted June 3, 2015 Thought I'd take the severe discussion local, since we're inside of 12 hours and small scale things might have an impact. SPC has the Metro area and the northern half of the I-25 corridor under the biggest gun for this afternoon/evening with a 10% tornado risk, 30% large hail risk and >10% hail over 2 inches. But we have this stratus layer which looks (so far) to be as far south as Castle Rock and as far west as C-470. I imagine it might erode as it continues to push south, and the boundary might be the stage. So this goes more with a line from perhaps Golden to Castle Rock to Parker and north and east a little from there for an area of focus, and that would go with the typical "hail alley" along the northern edge of the Palmer Divide...not so much north and east as SPC seems to say. I'm not as familiar with the North Metro area as far as mesoscale stuff goes. BTW I parked all the cars inside and moved furniture under the patio roof. Thoughts from those who actually know things are welcome! Link to comment Share on other sites More sharing options...
SluggerWx Posted June 3, 2015 Share Posted June 3, 2015 Thought I'd take the severe discussion local, since we're inside of 12 hours and small scale things might have an impact. SPC has the Metro area and the northern half of the I-25 corridor under the biggest gun for this afternoon/evening with a 10% tornado risk, 30% large hail risk and >10% hail over 2 inches. But we have this stratus layer which looks (so far) to be as far south as Castle Rock and as far west as C-470. I imagine it might erode as it continues to push south, and the boundary might be the stage. So this goes more with a line from perhaps Golden to Castle Rock to Parker and north and east a little from there for an area of focus, and that would go with the typical "hail alley" along the northern edge of the Palmer Divide...not so much north and east as SPC seems to say. I'm not as familiar with the North Metro area as far as mesoscale stuff goes. BTW I parked all the cars inside and moved furniture under the patio roof. Thoughts from those who actually know things are welcome! Just posted this in the other thread, but sky is already clearing here in Centennial/Englewood. This could be quite an interesting day. Link to comment Share on other sites More sharing options...
SluggerWx Posted June 3, 2015 Share Posted June 3, 2015 Forecast discussion from about 2 hours ago is pretty interesting - they call out the clearing likely to happen by 12PM-ish:THE FORECAST IS STILL ON TRACK...ALTHOUGH THE LOW CLOUDS MAY LIFTBY NOON. MOIST UPSLOPE FLOW...LARGE CAPES...LOW LEVELSHEAR...HIGHER THAN AVERAGE HELICITIES...A JET ALOFT ALL POINT TOTHE LIKELY DEVELOPMENT OF SUPERCELLS...POSSIBLY MOVING ACROSSMETRO DENVER OR THE URBAN CORRIDOR BETWEEN 3 AND 6 PM. A SUPERCELLTORNADO WILL BE POSSIBLE...ALONG WITH GOLFBALL TO BASEBALLHAIL...RAINFALL RATES OF AN INCH AN HOUR. WITH STRONG WINDS ALOFTSTORMS MAY MOVE EAST AT 30 MPH. WHAT IS UNCLEAR IS WHETHERCONDITIONS WILL BE TOO STABLE ON THE PLAINS FOR SUPERCELLS TOMAINTAIN THIS EVENING....ALTHOUGH WILL KEEP FORECAST OFPRECIPITATION SPREADING EAST THIS EVENING. THE LOCATION OF THE JETALOFT WORKING WITH THE TERRAIN WILL LIKELY DICTATE THE LOCATION OFSUPERCELL DEVELOPMENT. Link to comment Share on other sites More sharing options...
frontranger8 Posted June 4, 2015 Share Posted June 4, 2015 Three simultaneous severe t-storm warnings going in the metro area right now. Furthest north one hit me on the way home with about the biggest hail I've ever seen in person, probably nickel-sized at times. I'll have to check my car for dents later. Link to comment Share on other sites More sharing options...
Chinook Posted June 4, 2015 Author Share Posted June 4, 2015 Big storm on the Palmer Divide; some rotation on this one, several hail reports Link to comment Share on other sites More sharing options...
SluggerWx Posted June 5, 2015 Share Posted June 5, 2015 It's been an interesting last hour to say the least here in Stapleton. Storms continue to seemingly generate out of nowhere to the SE of us. Went from calm/clear to ping pong hail about 45 minutes ago.Now it looks like we're about four miles from 2 inch hail. Link to comment Share on other sites More sharing options...
frontranger8 Posted June 5, 2015 Share Posted June 5, 2015 Insane storm this evening. I've never seen so much lightning in my life. Fortunately, the big hail has avoided here so far. Link to comment Share on other sites More sharing options...
Chinook Posted June 10, 2015 Author Share Posted June 10, 2015 Yesterday was our first 88 of the year (87.9 at Fort Collins, 90 at FNL airport). It was 85 at Denver. It felt so warm compared to the previous few weeks. We had sunshine all day. The KDNR soundings yesterday showed 0.59" and 0.82" of precipitable water. These values are fairly normal PW values for mid-summer, but there was little cloud development anywhere near here. Now. thanks to the SPC sounding climatology, I know that 0.71" is Denver's average P.W. for late July. Mid-June should average 0.6" of P.W.. Just think, last year we maxed out at 99 here. I suppose we can expect above-normal dew points this summer, with an almost daily chance of rain. I think our area will have above normal precip. this summer, just due to moisture feedback. I am not exactly sure how El Nino normally interacts with the summertime weather. When I lived in Ohio, ENSO wasn't a very good predictor for summertime. Edit: flash flood watch issued for our area, valid tomorrow. The 4km NAM shows areas of over 2" of rain near Denver in the next 36 hours. Based on yesterday's models, this is a bit of a surprise. The GFS shows PW values of 1.2" at Denver tomorrow night (200% of normal.) ...FLASH FLOOD WATCH IN EFFECT FROM THURSDAY MORNING THROUGHFRIDAY MORNING...THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A* FLASH FLOOD WATCH FOR PORTIONS OF CENTRAL COLORADO...EAST CENTRAL COLORADO... Link to comment Share on other sites More sharing options...
frontranger8 Posted June 11, 2015 Share Posted June 11, 2015 Yeah, the next 48 hours are looking very wet. Almost certainly will be more flooding with how saturated the ground still is. Pretty unusual to have not hit 90 yet at DEN or BOU. Probably will be another week at least. Link to comment Share on other sites More sharing options...
Chinook Posted June 11, 2015 Author Share Posted June 11, 2015 Heavy rain rates already affecting Loveland US34/I25 intersection MESOSCALE PRECIPITATION DISCUSSION 0193NWS WEATHER PREDICTION CENTER COLLEGE PARK MD219 PM EDT THU JUN 11 2015 AREAS AFFECTED...SECTIONS OF SOUTHEAST WY & EASTERN CO CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE VALID 111819Z - 120019Z SUMMARY...THUNDERSTORMS HAVE BEGUN TO DEVELOP ACROSS SOUTHEAST WYAND EASTERN CO. WITH THE POTENTIAL FOR HOURLY RAIN RATES UP TO1.25", FLASH FLOODING IS POSSIBLE.DISCUSSION...WEAK UPSLOPE FLOW BEHIND A COLD FRONT COMBINED WITHAN UPPER LOW TO THE WEST AND 500-1000 J/KG MLCAPES HAVE LED TOTHUNDERSTORM DEVELOPMENT ACROSS SOUTHEAST WY AND EASTERN CO. Link to comment Share on other sites More sharing options...
mayjawintastawm Posted June 11, 2015 Share Posted June 11, 2015 Have to say it's been an absolutely gorgeous day here in Aurora. There seems to have been a force field around the Denver Metro area with a radius of 25-30 miles. However, it appears that it is starting to break down; it is significantly less gorgeous with temps having dropped 10-15 degrees and E winds picking up to about 20 mph. Link to comment Share on other sites More sharing options...
Chinook Posted June 14, 2015 Author Share Posted June 14, 2015 A couple of pics from ordinary (non-sheared) storm development near here. I didn't see any rain yesterday, but I did see darker skies and some mammatus. Link to comment Share on other sites More sharing options...
Chinook Posted June 16, 2015 Author Share Posted June 16, 2015 This isn't exactly near here, but I may as well cover it. Heat wave at Needles, CA. Yesterday,June 15, Needles had a high temp of 46.1 C (115F) KEED 152356Z AUTO 20013G19KT 10SM CLR 45/M03 A2965 RMK AO2 SLP998 T04501028 10461 20411 56017 Link to comment Share on other sites More sharing options...
Chinook Posted June 16, 2015 Author Share Posted June 16, 2015 Severe watch for the northern tier of Colorado. I've never seen a narrow strip from NW edge of Colorado to the NE edge of Colorado in a severe watch. http://www.spc.noaa.gov/products/watch/ww0304.html tornado watch for the North Platte CWA type area. Considering the strong shear in Wyoming, maybe they should have gone with a tornado watch for Wyoming. Storm with a hook-shaped feature (not necessarly a supercell) oddly shaped cloud with a little rotation Link to comment Share on other sites More sharing options...
Chinook Posted June 17, 2015 Author Share Posted June 17, 2015 107 degree dew point depression Conditions at: KLAS observed 16 June 2015 21:56 UTC Temperature: 41.7°C (107°F) Dewpoint: -17.8°C (-0°F) [RH = 2%] Link to comment Share on other sites More sharing options...
Chinook Posted June 20, 2015 Author Share Posted June 20, 2015 Yesterday's high temps ranged from 93 to 97 around Fort Collins. Here is the FNL airport METAR with the high temp listed as 36.0 celsius (96.8F) Dew points in the morning were near 60, and then the moisture mixed considerably, so there was a dew point of 33 for a short while. KFNL 192355Z AUTO 14006KT 10SM CLR 35/08 RMK AO1 10360 20280 403600170 Greeley high temp: 37.0 celsius (human body temperature, i.e. 98.6F) KGXY 192355Z AUTO 13008KT CLR 34/04 A2986 RMK AO1 10370 20270 403700150 57017 Link to comment Share on other sites More sharing options...
mayjawintastawm Posted June 24, 2015 Share Posted June 24, 2015 Suddenly we're in the time of year where it is hot and dry and we get ready to go for a swim after dinner and I tell my wife "nothing on the radar, let's go" .... them 20 minutes later it's dark and rumbly and threatening hail. Sheesh. Link to comment Share on other sites More sharing options...
Chinook Posted June 24, 2015 Author Share Posted June 24, 2015 We may have some scattered severe storms on the Front Range corridor tomorrow. Link to comment Share on other sites More sharing options...
mayjawintastawm Posted June 25, 2015 Share Posted June 25, 2015 Today was Bike to Work day in metro Denver. I had a nice ride from Greenwood Village to Aurora. Then I left work at 4:30. There was a rotating shelf cloud a couple miles to my west. Nice also. Then it rotated more. Then it did not go north as I thought it would. No sirens, no warnings. Then I decided I needed to find some shelter anyway, and 30 seconds after I found some there was a warning on my phone and a siren at the same time. And the tops of trees started blowing off, but I was told there was no touchdown. Anyway, moral of the story is: I do NOT recommend storm chasing by bicycle. Link to comment Share on other sites More sharing options...
mayjawintastawm Posted June 25, 2015 Share Posted June 25, 2015 Update: possible F0 tornado 2 miles north of where I was. Too freaking close, and rain wrapped to boot. Link to comment Share on other sites More sharing options...
Chinook Posted June 25, 2015 Author Share Posted June 25, 2015 This storm popped up right over Denver and went to 60+ dBz with hail very quickly. I hope everybody was alright. I'm sure a few cars got dented around the areas of 1.5" hail. Link to comment Share on other sites More sharing options...
Chinook Posted June 25, 2015 Author Share Posted June 25, 2015 Severe thunderstorm watch includes Denver city/county -- THE NWS STORM PREDICTION CENTER HAS ISSUED A * SEVERE THUNDERSTORM WATCH FOR PORTIONS OF NORTHEAST COLORADO WESTERN NEBRASKA SOUTHEAST WYOMING Link to comment Share on other sites More sharing options...
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