Wednesday, August 31, 2016

Gradual Cool Down Thankfully Coming

Fall can't come soon enough.  Yesterday's high at the Salt Lake City airport reached 98ºF and was followed by a minimum last night (through 6 AM MDT) of only 74ºF.  Mother Nature really teased us last night as temperatures dropped quickly after 7 PM, but hopes of cool air pouring through the windows were quickly dashed as temperatures flatlined near 80ºF for much of the night.

Source: MesoWest
Today and tonight will probably be near repeats with a high near 98ºF and a low tonight in the mid 70s.  There is hope in the possibility of an isolated thunderstorm.  If you one of the chosen ones to receive rain and evaporatively cooled air, consider yourself fortunate.

The good news is that a gradual cool down is coming.  The GFS 700-mb temperature and wind analysis and forecast loop below shows the slow movement of cooler air associated with the upper-level trough presently over the Pacific Northwest into northern Utah later this week into Saturday morning.


Emphasis, however, on gradual.  Temperatures will be a bit cooler than today on Thursday and Friday, but highs will still likely be in the 90s.  Labor Day Weekend, however, looks quite pleasant.  If you will be in Salt Lake and environs, I think you will like it.

Tuesday, August 30, 2016

Hawaii in the Gunsights

Picturesque Hawaiian waterfalls could be roaring soon
Two powerful hurricanes have developed over the tropical eastern Pacific and are headed westward toward Hawaii.  Hurricane Madeline is currently (1200 UTC 30 Aug) a category 4 hurricane and will be the first to approach the islands on Wednesday and Thursday.  It is the westernmost hurricane in the image below.  Hurricane Lester is farther upstream (east) and a potential player for the Labor Day Weekend.


Based on analyses from the National Weather Service Central Pacific Hurricane Center, about 22 tropical storms and hurricanes have passed within 200 miles of Hawaii since 1950 and 10 have passed within 75 miles.

Source: NWS/CPHC
Model guidance presently shows a wide range of tracks for Madeline as she approaches Hawaii.  The GFS ensemble has a few bringing it directly over the Big Island, but others push her further south.  

Source: NCAR/RAL
A look at a multi model suite shows a couple of tracks that pass between the Big Island and Maui, but others going to the south.  


The official track cone, which represents the area that is likely to include the probable track of the tropical cyclone center, extends from the center of the Big Island southward.


Madeline is expected to weaken some as it approaches Hawaii, but will still be a dangerous storm with hurricane-force winds possible on the Big Island on Wednesday (depending on track and intensity), heavy rain on the Big Island and possibly other Hawaiian Islands Wednesday through Friday, and dangerous surf.  Official graphics and forecasts are available here.

As a mountain meteorologist, I'm interested in seeing how precipitation is affected by the interaction of the system with the topography of the Big Island.  I plan to keep an eye on this over the next couple of days.

Monday, August 29, 2016

Summer 2016 Destined for "First Loser"


It has been a hot, miserable summer, but it is now apparent that despite all the misery, 2016 is destined to only be the 2nd hottest summer on record in Salt Lake City.  In other words...

First Loser!

With 3 days left in meteorological summer (including today), the average temperature is 80.2ºF, a full degree ahead of 3rd place 2012, but 0.5ºF behind 2013.

Source: NOAA Regional Climate Centers
A half degree doesn't sound like much, but that's a difference in averages over about 90 days and even Ricky Bobby chasing Jean Girard can't make up ground like that.  

But don't be depressed.  If soccer can add extra time, we can add more laps.  We may be 2nd for summer, but we still have a shot at the hottest year on record.  For the year to date, we are only 0.1ºF behind 2015 for hottest on record, so we could go for the annual record.  

Source: NOAA Regional Climate Centers
Of course, breaking that record would probably require a warm November and December.  Let's not go there...

Sunday, August 28, 2016

Northwest Utah on Wrong Side of Tracks Again

Did you know that the high yesterday in St. George was 85ºF.  Cedar City reached only 71ºF!  Oh to experience a day like that.  Then there was that tornado in Panguich on Friday.  What gives?

Not much really.  Northwest Utah has simply been just to the north of the monsoon moisture and the weak disturbances that have helped to initiate thunderstorm activity for most of the summer.  Indeed that was the case yesterday.  As the analysis for 1200 UTC (0600 MDT) yesterday morning shows, a weak trough was centered right over St. George with clouds over most of the southern half of the state.  Once again, we were left high and dry.


I would give anything for grey overcast with steady rain all day.  Until that day comes, I'm resigned to listening to Natalie Merchant and dreaming.

Friday, August 26, 2016

Downscaled Forecasts from the Short-Range Ensemble Forecast (SREF) System

Alex Weech, an extremely capable undergraduate who has been working with me this summer, recently added downscaled precipitation forecasts from the National Centers for Environmental Prediction (NCEP) Short-Range Ensemble Forecast (SREF) system to the suite of products we have available at weather.utah.edu.

The SREF is a 26 member ensemble that includes forecast from two different modeling systems, the NCEP Eulerian non-hydrostatic multi-scale model (NMMB) and the Advanced Research version of the Weather Research and Forecasting Model (WRF-ARW).  Yes, I know these are terrible acronyms.  They don't call NOAA the National Organization for the Advancement of Acronyms for nothing (technically the WRF-ARW is not a NOAA product, but that doesn't make it any easier).

The SREF is initialized at 03, 09, 15, and 21 UTC and produces 87 hour forecasts at 16-km grid spacing.  We then downscale those to 800-m grid spacing using climatological precipitation analyses.  For now, we are generating plots showing precipitation forecasts for the entire 87-hour period.  An example from this morning's 15 UTC run is below.

We are also generating plume diagrams.  Since the weather in northern Utah is pretty uninteresting, here's the plume for Wolf Creek Pass, Colorado.

You will notice in that plume diagram that there is a strong clustering of forecasts by model, with the ARW being wetter and the NMMB being drier.  That's a fairly common characteristic of the SREF and one that we will have to examine to see if it skews the probability statistics for the forecasts.  And, with that being said, I really don't know how good these forecasts will be.  We'll start taking a look and perhaps by ski season we'll know whether or not to continue looking or just come up with a large sum of money to buy the ECMWF ensemble forecasts...

Wednesday, August 24, 2016

Japow Dreaming

With Dave Hanscomb, Hakuba Valley, Japan, February 1998
For much of my life I have been studying lake-effect and orographic (i.e., mountain) snowfall in some way shape or form.  This includes scientific investigations as well as personal adventures involving face shots, chin ticklers, and bottomless powder.

I was first introduced to the incredible snow climate of Japan in 1998 when I visited the Hakuba Valley during the Nagano Winter Olympics.  I was there for only four days, however, and much of my time was spent conversing with meteorologists involved in weather support for the Games.  I had time for only a brief taste of Japanese powder skiing when the Men's Super-G was cancelled, allowing for a couple of hours of storm skiing at Happo Ono resort.  

Storm skiing, Happo Ono, February 1998.  Just me and a few security guards near the top of the Men's Super-G.
This winter I will finally be traveling back to Japan and hopefully getting another taste of Japow.  I plan to travel to Nagaoka to begin a collaboration with scientists at the Snow and Ice Research Center of Japan's National Research Institute for Earth Science and Disaster Prevention to better understand orographic enhancement of lake-effect precipitation through study of storms across a wide range of geographic and topographic environments.  

I am hoping to tack on a few days of skiing in the Hakuba, Myoko, and/or Tenjin areas.  If you can share any beta on tours or guides, add a comment or send me an e-mail directly (jim.steenburgh at gmail.com).