Wasatch Weather Weenies

Note : The title of this post has been updated to fix a horrific grammatical gaffe! Things played out last night pretty much as anticipated for the past few days with a decent round of frontal precipitation, but not much thereafter.  The upper Cottonwoods did the best with 4–7 inches.  I score this EC 1 GFS 0 . The possibility of snow showers at times will persist through the weekend, but accumulations in the mountains will be minimal.  The GFS was advertising a possible snow event for Sunday, but not surprisingly, it has now shifted to the drier EC solution.  It's too soon to say EC 2 GFS 0 , but that's looking likely. I am, however, getting enthused about what I am seeing for Sunday night and Monday, and this is probably the first time this season that I've said anything remotely like that.  The GFS is advertising a strong cold frontal passage Sunday night with a pretty good push of cold, moist, northwesterly flow in its wake. Unlike previous storms...

Source: Forbes Many of you have asked or commented about difference in the temperature trends from satellites or surface-based thermometers, as well as the adjustments that are made to these records. Marshall Shepherd has an outstanding piece in Forbes today fully summarizing the issues at play .  Marshall is the Director of the Atmospheric Sciences Program at the University of Georgia, host of the Weather Channel show Weather Geeks, and a NASA scientist.  He was also the 2013 President of the American Meteorological Society.  He's an outstanding scientist and an outstanding scientific communicator. It's clear that Marshall put a great deal of thought went into explaining the strengths and weaknesses of the two approaches.  Note that he emphasizes the importance of looking at the climate system holistically, including the use of oceanic heat content, rather than just surface temperatures.  This is something that we have discussed in previous posts (see G...

There's not much change in the weather forecast from yesterday.  A cold front will move across northern Utah late today and early this evening, ushering in a period of mountain snow.  Snow on the benches may begin as rain and turn to snow, with the transition happening a bit later on the valley floor.  I'm sticking with 4-8 inches for Alta-Collins.  Although mountain snowshowers are possible at times in the wake of the system through Saturday, as things look now, I'm not expecting any major accumulations in that period.  The US models are advertising mountain snow for Sunday associated with a warm-frontal passage, but the EC is a bit less enthusiastic.  Both models are encouraging for the cold-frontal passage on Sunday night.  Keep your expectations low and your hopes high. In other news, the Climate Prediction Center (CPC) issued their monthly El Nino/Southern Oscillation (ENSO) Diagnostic discussion and not surprisingly, El Nino remains quite stron...

Although there is quite a bit of spread amongst the various models concerning precipitation, they are in good agreement that we will see a frontal passage late Thursday.  The image below is the 1200 UTC GFS forecast valid for 5 PM MST tomorrow (Thursday) showing the front entering the Salt Lake Valley at that time.  The timing is a bit earlier in the 1200 UTC NAM and the 0000 UTC EC. Those of you still walking around in shorts on campus might want to think about wearing pants if you will be heading home late in the afternoon as it will probably be blustery in the post-frontal environment, although it's tough to say of snow levels will immediately drop to bench levels right after the frontal passage or if that will take a couple of hours longer. I'm seeing some odd precipitation numbers being generated by the various models for the frontal passage.  From 5 PM Thursday to 5 AM Friday, the 12-km NAM calls for .85" of water and about 13" of snow for Alta-Collins. ...

In yesterday's post, I asked the question, " should we buy in to the latests forecasts ?" Motivating that question was the very optimistic forecasts for snow being produced by the GFS and the NAEFS, as well as the less optimistic forecasts being produced by the ECMWF Integrated Forecast System (a.k.a., the ECMWF, EC, or Euro model and ensemble). Given the restricted nature of data provided by the ECMWF, I've struggled with how to show these differences, but someone pointed out to me that San Jose State University has a comparison between the EC and the GFS on their web site .  I love it when my job gets easier. So, here's the basic issue.  Yesterday mornings 1200 UTC GFS (green 500-mb height contours below) produced a much weaker and progressive trough than the EC (red contours) for later this week and weekend.  These result in dramatically different forecasts for precipitation in the central Wasatch, with the former being wetter and more favorable for orograp...

Snowfall has been scarce in the central Wasatch so far this season and since mid-November Alta has reported only 13" of snow.   Storms that have looked good in the GFS at Day 7 have consistently fallen apart.  The latest GFS forecast looks enticing, but at issue is whether or not to get excited. In the short-term, we have two brush-by systems that might bring a bit of snow to the mountains tonight and late Wednesday.  Emphasis is on a bit, but even an inch or two would help.  Then, the GFS is advertising a fairly significant pattern shift later in the week with a deep, digging trough pushing into the western U.S.  As currently advertised by the GFS, there's a healthy frontal passage late Thursday and then a series of weak troughs that give us some additional shots of precipitation in the post-frontal northwesterly flow. Although past events have sometimes featured NAEFS ensemble members that have been fairly dry, all the members are giving us something de...

There's some hope for snow in the latter half of the upcoming work week, but not much will happen between now and then other than the continued rotting of the snowpack.   Rather than being out in the field watching facets grow on Wednesday afternoon, those of you with an interest in snow science might want to attend a seminar that will be given at the U by Jordy Hendrikx.  Jordy is director of the Snow and Avalanche Laboratory at Montana State University and Chair of the Research Committee for the American Avalanche Association.   Photo Credit: Karl Birkeland Here are the details: Snow Science: Taking a Multi-Faceted Approach to Understand Avalanches Jordy Hendrikx, Montana State University Wednesday, December 9, 2015 INSCC 110 University of Utah Refreshments and Meet the Speaker at 3:00pm and Seminar at 3:15pm Map:  http://bit.ly/1ljehqL