The Inversion is Gone, but Heavy Snows in Tap

      As you can see from the picture below most of the smog and junk from the last 2 weeks is out of here, as if we have not  payed the price with this inversion already we are going to add insult to injury and bring in a potent snowstorm today.

   

 As you can see the NWS has winter weather advisories and warnings in place.

Here is UDOT'S take on the approaching storm

So lets get down to business with snow amounts, today-tonight's storm keeps trending snowier in all models, and slows the front down across N. Utah that is why the nws has upgraded the nothern wasatch mountians and valleys to a warning, click here to visit the nws page current thinking for the valleys is that Farmignton north will get the goods prob. anywhere from 5-8"+, but if the front stalls a little bit further south then places like Bountiful and Possibly SLC will receive more, for the rest of the Wasatch Front my guess would say 3-6 inches, but as i said the last 2 models have generated quite a bit more, so don't be surprised to see 8+. 

A bit of a break Monday afteernoon and night then the 2nd storm moves in, this will be a diffrent type of storm which will be a warm advection, which is when there is no front associated with it, just lifting of the low levels of the atmosphere, these events are hard to predict amounts but current thinking is 3-6"+ in the valleys, with a another light snow event on Wednesday. Enjoy

As for the Wasatch Mountains, looks like a good 8-14" with this 1st storm, them a 5-10" with the 2nd storm on Tuesday which adds up to 1-2' feet of snow, great skiing days on Monday-Thursday!

Powder Days Ahead

Who is ready for some more POW

     Tonight-Saturday the Wasatch mountains should receive 6-12" of snow and the valleys might squeeze out 2" while the benches might receive 4".

      Sunday -Sunday night was once a pretty good looking storm according to models a few days back, now most likely a warm advection type storm, which means no front crossing the area, so looks like the Wasatch will receive another 4"-8" of snow and the valleys maybe another 2"-3" and benches 3"-5" Poss. more will have to watch this one.

Tuesday-Wednesday still looks like a very potent storm for the area, a strong cold front blasts thru around the evening commute tuesday, might have to watch this one as temps will fall in the 20's behind the front so accumulating  road snow and ice will be a good bet, right now i am thinking 1'-2' + for the Wasatch mountains with valleys 6"+ and benches 12"+.  Plus there is a chance of DLE (dreaded lake effect ) Wednesday morning.

If you have not tuned up the Snow blower now is the time!




 


Stay tuned will update tomorrow! 

Old Man Winter Will Be Busting Down The Door

For the last 5 days or so models have been showing the front entering Northern Utah late Thursday evening and moving the SLC area around midnight. Now both the NAM and GFS are showing a delay in the onset of precipitation until late morning Friday. Not a ton of moisture with the initial front but could see a brief period of moderate to heavy snow in the mountains and lighter snow in the valley during the day Friday. There may be a break after the front on Friday evening before the instability and moisture associated with the cold pool move into the area. Friday night and Saturday we’ll see the best dynamics and the best orographics for widespread moderate to heavy snowfall. There will be a good chance for lake enhancement or a lake effect band downwind of the lake. Best guess right now would be east-southeast of the lake. Over southern Davis County and Northern Salt lake County toward Park City. We’ll have to monitor the lake effect situation as we get closer as it is notoriously difficult to forecast.

When we look at the two aspects of this system, the front and instability behind the front, we can split the system into two separate parts to make our snowfall predictions. The initial front on Friday looks like it will put down 4-8″ for the mountains and only a couple inches in the valleys. Then the cold pool on Saturday has potential to drop up to 6″ in the valleys with more than that possible under lake effect band if one sets up. The mountains will likely see over a foot of snow on Friday night-Saturday night time frame. There isn’t incredible moisture associated with the system. But the direction of the flow aloft will allow for good orographics and the cold air will create very high snow:water ratios so just 1 inch of liquid qpf will likely yield 18 inches of snow.

With all that in mind, by midday Sunday, we expect the following totals:
1-2 feet above 7,000 ft. (with possibly more in orographically favored areas or under lake effect band)
6-12 inches in mountain valleys / high benches of Wasatch Front
Up to 6″ on valley floors

Next week is still a little unclear but it’s looking like we may be clipped by another system mid-week however it looks weaker/warmer. We’ll keep our focus on the storm at hand for now.

Wet Week Ahead

Everything is set and ready to go.  Models continue to be in very good agreement for the most part through Thursday. Utah is primed for its first winter like pattern.

           Looking at all the charts this morning I’m feeling comfortable with the forecast which went back and forth on the strength of these systems all last week but settled in on a solution on Friday and for the most part has stayed on that solution since Friday.
       Today we’ll have the first of the stronger waves of precipitation approach the area.  All models now don’t show the bulk of the precip arriving until tonight, but showers will still be possible all day with warm, moist flow over the area.  Tuesday morning, snow levels will start to finally lower below 8,000 feet, possibly falling as low as benches and even valley floors by Tuesday evening.  Snow will start accumulating in the mountains on Tuesday and it should snow off and on through Thursday as reinforcing shots of energy rotate into the region.

       Wednesday will be colder as the cold pool of the parent Low works its way into the Wasatch.  We should see snow levels fall all the way to valley floors according to the 12z run of the NAM (computer model).  Grassy surfaces may see light accumulations but warm pavement temps should keep road accumulations minimal.
By Thursday night, we’ll start to dry out as a ridge builds in for next weekend, though temps should remain cool.

Accumulations:
      Right now we’re still thinking 8-16″ total above 8,000 ft for Monday-Thursday.  Mountain valleys will probably see 4-8″.  Benches of Wasatch could see a couple inches later in the event.

 

Old Man Winter is knocking on the door . . .

            Everything is starting to look a little clearer through at least Wednesday of the upcoming week.  The Wasatch and adjacent Wasatch Front will see its first real winter pattern this week with one large Low sending in reinforcing impulses every 24 hours starting today.Click here for latest western satellite.     Today’s impulse will do little more than bring in some clouds, winds, and slightly cooler temps.  Tomorrow’s will be a little stronger with a slight chance for showers.  The first real threat for accumulating snowfall will start on Monday in the mountains with rain showers in the valleys below 6,000 ft.  At this time it looks like rain and snow will increase in intensity on Monday into Monday night before clearing out Tuesday morning a bit before a reinforcing wave of energy picks things up a bit on Tuesday evening through Wednesday.  This latter impulse could be strong and cold enough to bring snow levels down to SLC valley floors, or at the very least, to the bench locations.

 Also of note is that the GSL temp is very warm which might bring us a lake effect storm! Here is the latest info for the lake:

WRF-NMM LAKE TEMPERATURE CALCULATION
LAST UPDATE: 05:45 UTC 10/20/2012
WEEKLY AVERAGED AVHRR-DERIVED TEMPERATURES       
7-DAY MEAN ENDING 10/15/2012
NORTH ARM
16.28 C
SOUTH ARM
15.77 C

CLIMATOLOGICAL LAKE TEMPERATURE                 
13.5 C
LAKE TEMPERATURE USED IN WRF
14.7 C

TLAKE EDITED IN WRF-NMM AT: 05:45:06 UTC 10/20/2012

As you can see the Avg water temp this time of year is 13.5 c (56.3 F) but with the HOT summer we had it is sitting at a mean of 16.0 (60.8). if we drop to -1c (30.1 F) we will be cold enough for lake enhanced or lake effect squalls, but there is a few more ingredients needed to make this happen as described below.

 

 Lake-effect and lake-enhanced snow is more complicated than just cold air within northwest flow moving over the warmer Great Salt Lake. The necessary ingredients include sufficient over-lake temperature differential (i.e. greater than 17C from the surface to 10,000 ft MSL or 700 mb), sufficient distance of air flowing across the lake (northwest or north flow provides this across the longer portion of the Great Salt Lake ), minimal change of wind speed or direction in the boundary layer, deeply unstable boundary layer (top layer above 600 mb level preferred for sufficient convective growth), adequate steering flow to develop banding, and over-water surface convergence which is often driven by a land breeze circulation under radiational cooling at night (air flowing toward the warmer water from the colder surrounding land). The lake bands can be further enhanced when they are sufficiently deep and extend well inland resulting in upslope flow of the moist air along the west slope of the Wasatch Range. For a given event the ingredients for lake-effect and lake-enhanced precipitation varies with respect to the potential for generating snow. This will determine if a lake band or lake enhanced area of precipitation will develop and how long and intense the snowfall will be.

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Fall is on the Way!

Well above average temperatures have been the main story for the last few days.  That is expected to change on Wednesday and beyond as a cold system will drop out of Canada into the interior sections of the United States.  Most of the energy will stay to our east and we’ll see little more than clouds, but temperatures will take a serious dive, dropping 10-15 degrees over Northern Utah.  After the front moves through, the intermountain west well be under a long-wave trough that will allow disturbances to periodically move through the area.  These are likely not to be precip producers, but will rather bring with them a few clouds and reinforcing shots of cooler temperatures through next weekend.  So enjoy the warmth for the next couple days before Autumn makes it’s return on Wednesday.  At this time, there is nothing in the future that screams, “snow”, but this time of year models have a difficult time dealing with global pattern changes as we transition seasons, and sometimes storms can pop up when we don’t expect them.  Until then, enjoy the beautiful Fall weather.