Chinook Posted October 5, 2017 Author Share Posted October 5, 2017 My best fall colors pic before it snows? Only time will tell Link to comment Share on other sites More sharing options...
raindancewx Posted October 6, 2017 Share Posted October 6, 2017 For anyone who saw the Accuweather winter outlook, it had a decent winter for much of the West, excluding maybe S. NM and S. AZ. Their long range forecaster apparently used a blend of 1960, 1979, 1981, 1983, 1996, 2013, 2014, and 2016, with 1981, 1996, and 2013 each double weighted. I'm not a fan of that blend, 1979 & 2014 were both borderline El Ninos, and most of those years are a lot colder in the Atlantic, and they tend to have high solar activity. More generally, 1983 & 2016 were both after super El Ninos, which tend to have lingering impacts. The PDO is super positive overall in those years too (largely from 2014, 1983, and 2016) which I don't buy for this year. http://www.city-data.com/forum/weather/2822099-winter-thread-2017-18-northern-hemisphere-10.html Link to comment Share on other sites More sharing options...
ValpoVike Posted October 6, 2017 Share Posted October 6, 2017 Currently it is 60 degrees at my home, and we just had a 5 minute snow shower. WTH? I guess the warm air is very shallow at this elevation... Link to comment Share on other sites More sharing options...
raindancewx Posted October 6, 2017 Share Posted October 6, 2017 4 hours ago, ValpoVike said: Currently it is 60 degrees at my home, and we just had a 5 minute snow shower. WTH? I guess the warm air is very shallow at this elevation... Its rare, but even down here we occasionally get accumulating snow into the upper 30s and 40s. It routinely snows / sticks (on cold surfaces) when over freezing and snowing in Oct/Nov, Mar-May. The record here is supposedly like 47F with snow because it was dry and in the low 30s even 500 feet off the ground. Link to comment Share on other sites More sharing options...
Chinook Posted October 6, 2017 Author Share Posted October 6, 2017 It might have been graupel, which could develop above the freezing level and survive the trip to the surface, like hail. There are about 25-30mph wind gusts here Link to comment Share on other sites More sharing options...
Chinook Posted October 7, 2017 Author Share Posted October 7, 2017 Regarding Monday: the 18z GFS has about 0.4" to 0.9" for Larimer County (me and ValpoVike), and about 0.34" for Denver. Some snow and some rain will fall at lower elevations. Have fun with this one, Valpovike. For me, it's too early for snow. Hopefully it's not too heavy for the trees and hopefully the tree colors won't be impacted too much by freezing temps. The cold temps of 15-20F at *exactly* this time of year (Oct 9) in 2009 really killed the tree colors later in that month. Link to comment Share on other sites More sharing options...
Chinook Posted October 7, 2017 Author Share Posted October 7, 2017 NWS Boulder discussion Quote Each of the medium range models have nearly similar timing with the arrival of the upper trough Sunday night. Cold temperatuers and snowfall are expected to continue through Monday as upslope low level flow continues with the upper trough also remaining over the state. Snow amounts along the I-25 corridor could be in the 3 to 6 inch range by Monday evening. The combination of gusty winds, falling snow and local vegetation still nearly in full leaf will make some highlight necessary. Link to comment Share on other sites More sharing options...
Chinook Posted October 8, 2017 Author Share Posted October 8, 2017 Pic from yesterday: here's some fall colors and a nice park and a cloud deck with a little waviness. And here's the GOES-16 satellite picture of the same cloud deck. Link to comment Share on other sites More sharing options...
Chinook Posted October 8, 2017 Author Share Posted October 8, 2017 first winter storm warning for me Quote * WHAT...Heavy snow expected. Some secondary roads and bridges and overpasses may become snow or slush covered. Plan on slow and hazardous travel conditions, including during the morning commute on Monday. Total snow accumulations of 4 to 7 inches are expected, heaviest amounts near the foothills. Link to comment Share on other sites More sharing options...
Chinook Posted October 8, 2017 Author Share Posted October 8, 2017 This looks like a January forecast Link to comment Share on other sites More sharing options...
raindancewx Posted October 9, 2017 Share Posted October 9, 2017 We're in a freeze watch down here. Don't think the city gets to 32F on Tuesday morning, but nice to see - we didn't drop below 44F at all last October. Our first frost is usually right around Halloween. Didn't happen til November 18th last year. Historical range here for first frost is 10/31, +/- 3 weeks, so it was definitely very late last year. These nights in the mid 40s have been nice for the Balloon Fiesta, since we still warm into the 70s during the day. Link to comment Share on other sites More sharing options...
Chinook Posted October 9, 2017 Author Share Posted October 9, 2017 We have light rain, 0.15" and cooling down. Cheyenne has had snow for 1 hr. It was a beautiful day with temps of 60 earlier. Link to comment Share on other sites More sharing options...
mayjawintastawm Posted October 9, 2017 Share Posted October 9, 2017 about 3" (deepest I could find, so I think given no significant wind it's valid) and a big branch just broke on one of our backyard trees which is still fully leafed out and green. Fortunately it didn't fall on anything of value. Grrr. Link to comment Share on other sites More sharing options...
Chinook Posted October 9, 2017 Author Share Posted October 9, 2017 The snow packed down a lot with temps of about 34. Maybe we had 2.5" with 0.30" or 0.40" liquid equivalent. The snow rate was pretty respectable, in the sense that a lot of decent sized snowflakes were falling. Fort Collins has gotten about 0.67" combination of rain and snow. There was definitely at least 0.17" of rain. Link to comment Share on other sites More sharing options...
raindancewx Posted October 9, 2017 Share Posted October 9, 2017 Given the lag between Nino 3.4 and the ENSO state, seems like we'll be in a Neutral pattern through December, with the weeklies rising now for three weeks in a row. Neutrals are good for CO snow early... La Ninas are good in the core of winter and El Ninos are good in Spring. So if we switch to more of a La Nina base in Dec-Feb, could be a pretty good Oct-Feb for snow in CO. Link to comment Share on other sites More sharing options...
ValpoVike Posted October 10, 2017 Share Posted October 10, 2017 We only received 7 inches up here, and the roads stayed relatively clear. I was down in FoCo much of today for meetings and it seemed to melt as fast as it was coming down, which is great news for the trees given the apparent high water content. Edit: I checked my weather station rain gauge and it shows .99 inches, which would be 7:1 and is very close to Chinook's estimates. This puts me at 18.05 inches for the year and a realistic shot of closing over 20, which would be in excess of 20% over what limited climatological data I can find. Link to comment Share on other sites More sharing options...
Chinook Posted October 10, 2017 Author Share Posted October 10, 2017 Total liquid equivalent here should be over 1". I will check CoCoRAHS web site tomorrow. The trees did not have a lot of problems, as the snow did not form large accumulations on tree leaves. Link to comment Share on other sites More sharing options...
mayjawintastawm Posted October 10, 2017 Share Posted October 10, 2017 Looks like closest COCORAHS to us wound up with 0.9" WE. Snow total at our house was 4.5", with a few spots over 4 feet though that was contaminated by wood and leaves. Our next door neighbors had a big silver maple branch fall on their garage roof, fortunately damage was minor. Link to comment Share on other sites More sharing options...
beavis1729 Posted October 10, 2017 Share Posted October 10, 2017 Laramie WY dropped to -2 this morning, shattering the old record of 7 set in 2009. Records go back to 1948. This has to be Laramie's earliest sub-zero temp on record...or close to it. Link to comment Share on other sites More sharing options...
raindancewx Posted October 12, 2017 Share Posted October 12, 2017 On 10/10/2017 at 2:15 PM, beavis1729 said: Laramie WY dropped to -2 this morning, shattering the old record of 7 set in 2009. Records go back to 1948. This has to be Laramie's earliest sub-zero temp on record...or close to it. A lot of years with 0F or lower readings by Oct 31 were used in my winter forecast - nice to see! I was considering using 1985-86 but the Atlantic was frigid that winter. 1970-71 came up as a 'Summer Conditions' analog. Used 1996 as a main analog. 2002, believe it or not came up as a similar Summer analog too. Link to comment Share on other sites More sharing options...
Chinook Posted October 12, 2017 Author Share Posted October 12, 2017 snow and some bright tree leaves Link to comment Share on other sites More sharing options...
Chinook Posted October 13, 2017 Author Share Posted October 13, 2017 Coming up in 36-60 hrs. This low pressure in the northern Plains should have some near-freezing temps east of central Wyoming. Maybe a few areas of snow east of Wyoming, if lucky (unlucky?) Link to comment Share on other sites More sharing options...
Chinook Posted October 15, 2017 Author Share Posted October 15, 2017 I guess Rapid City, snow-wise, is kind of a mix between the very snowy northern Black Hills (north wind blizzards,) and normally dry western Dakotas. And when I say normally dry, I mean the western half of the Dakotas, (Black Hills excluded) have relatively low amounts of snow and rain, although the snow could last a long time. Link to comment Share on other sites More sharing options...
raindancewx Posted October 16, 2017 Share Posted October 16, 2017 Just a bit of amplification in the pattern this month. The look so far is actually not super far off from what I put out what for winter, but I think it relaxes/reverses at times, and its further south as the cold air builds. We shall see. Pretty sure Nov is going to be quite warm for much of the West though. Link to comment Share on other sites More sharing options...
Chinook Posted October 16, 2017 Author Share Posted October 16, 2017 We'll start the winter thread whenever my point&click forecast doesn't say 70 degrees, which should be within the next 7 days. Link to comment Share on other sites More sharing options...
ValpoVike Posted October 16, 2017 Share Posted October 16, 2017 1 hour ago, Chinook said: We'll start the winter thread whenever my point&click forecast doesn't say 70 degrees, which should be within the next 7 days. Obviously a long ways out, but the GFS is sniffing around a broad cold air intrusion for the 26th and 27th. Link to comment Share on other sites More sharing options...
Chinook Posted October 16, 2017 Author Share Posted October 16, 2017 Yep, the 26th-28th could be a turning point to wintry weather, say, for example, high temp of 45, chance of snow (for 5000-5200 ft). Let's see if the GFS ensembles and ECMWF ensembles trend this way in the next couple of forecasts. Link to comment Share on other sites More sharing options...
Chinook Posted October 17, 2017 Author Share Posted October 17, 2017 This probably made some neat lenticular clouds near Denver. I got a pic of some thin lenticular clouds about 1 hr after this (satellite image is from 18:02z) Link to comment Share on other sites More sharing options...
raindancewx Posted October 17, 2017 Share Posted October 17, 2017 Last year, the La Nina was starting to peak about this time. With cold Neutral conditions for the moment, Nino 3.4 is way warmer than last year. The changes y/y resemble a Modoki El Nino, although the tropical Pacific is cold overall in absolute sense. Atlantic is colder near the US - always a good sign for wetness/moisture out here. Link to comment Share on other sites More sharing options...
Chinook Posted October 19, 2017 Author Share Posted October 19, 2017 Moderate to strong La Nina years: (see list of years.) If you composite these temperatures vs. the 1981-2010 normal temperatures, you find below normal to normal temps from Los Angeles to Denver. That does not mean that all these Southwestern areas have above normal precip; they do not. North Central and West Colorado climate divisions average above normal precip, but most of the Southwest is below normal. The upcoming winter is not necessarily a strong La Nina-- it hasn't even formed into a La Nina yet. Link to comment Share on other sites More sharing options...
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