tag:blogger.com,1999:blog-6168620747792092240.post4160731096945825677..comments2024-03-27T15:09:59.039-06:00Comments on Wasatch Weather Weenies: Upcoming Intermountain Cyclogenesis EventJim Shttp://www.blogger.com/profile/15799757451626876963noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-6168620747792092240.post-18437630421407156912011-02-26T12:21:37.872-07:002011-02-26T12:21:37.872-07:00It seems like the SST minimum is part of it. I thi...It seems like the SST minimum is part of it. I think most of the NH reaches this minimum around the first of March, while the CA coast SST obs seem to suggest that April is the coldest there (some of the buoy sites on http://www.ndbc.noaa.gov/ have monthly average SST plots). There also seems to be much more of a tendency for deep trough development over the southwestern U.S. (including California) in the spring. This may have a strong relationship to the severe weather maximum in the plains states in the spring also, which they really don't see in the fall to anywhere near the same extent.Davidhttps://www.blogger.com/profile/02814313368731066590noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-13719476668438749392011-02-26T10:03:20.581-07:002011-02-26T10:03:20.581-07:00It seems that most of the strong frontal systems o...It seems that most of the strong frontal systems occurring in the Great Basin during the spring are driven by the deep, mid-tropospheric closed lows Jim mentioned - possibly many of the same systems that bring California some of its higher snow/rain ratio precipitation events. If experience serves me right (not always!), it seems that the typical path for these closed lows to take into this area is southward near the U.S. west coast...<br /><br />Is it possible that the minimum in regional SST over the EPAC during this time of year lends itself to a much smaller amount of heat release into the closed lows moving overhead? This might result in less airmass modification, increasing the snow/rain ratio, and aiding in driving strong cold fronts once these upper-level systems come ashore.JonRhttps://www.blogger.com/profile/17486257474365885398noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-45311860908319537662011-02-25T23:35:46.917-07:002011-02-25T23:35:46.917-07:00I suspect it may have a lot to do with storm track...I suspect it may have a lot to do with storm track, and the Bell paper does show a strong maximum in closed low activity near California in the spring. However, I also looked at some buoy data, and SST's near CA appear to reach a minimum around April. This late SST minimum did not seem to be the rule further north (WA/OR). In any case, I think that the apparent spring temperature minimum of these west coast (or at least California) storm events may be a significant factor in the intensity of intermountain frontal systems in the spring.Davidhttps://www.blogger.com/profile/02814313368731066590noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-47121530411290448532011-02-25T17:54:40.977-07:002011-02-25T17:54:40.977-07:00I'm not familiar enough with the Pacific SST c...I'm not familiar enough with the Pacific SST climatology to comment on that portion of your hypothesis. I suspect, however, that the frequency of deep mid-tropospheric closed lows may be highest along the California coast in the spring. See Bell and Bosart (1989, MWR). I can't access this from where I'm sitting, so I'll leave it to you as a research exercise :-).Jim Shttps://www.blogger.com/profile/15799757451626876963noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-72845649674075019002011-02-24T22:35:50.662-07:002011-02-24T22:35:50.662-07:00I read your 2008 paper and found it very interesti...I read your 2008 paper and found it very interesting. I have noticed one factor (perhaps this was mentioned somewhere) that may contribute to this increase in cold front intensity. Working with some weather-related projects in California over the last several years, I have observed that many of their coldest storm events tend to take place in early spring. In fact, analysis of the snow:rain (or snow:total monthly precip) ratio shows that this ratio tends to peak in March at many sites. A good example with a long-term climatology is Blue Canyon, where this ratio is highest in March and second highest in April (http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca0897). A spring storm temperature minimum, if this is indeed the case, might be due primarily to the sea surface temperature minimum near early spring, or perhaps more to seasonal changes in storm track and jet stream patterns. What is your impression of this?Davidhttps://www.blogger.com/profile/02814313368731066590noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-29506293428777370812011-02-24T07:09:22.209-07:002011-02-24T07:09:22.209-07:00Does it follow that DRE events increase in frequen...Does it follow that DRE events increase in frequency and "severity" during spring as well? I suppose it gets hard to define, count, and catagorize DRE events to begin with ....tcruickshttps://www.blogger.com/profile/06730530603038741779noreply@blogger.com