Rain Changes to Snow in Salt Lake City on Tuesday

A warm southwest flow will remain over Utah on Monday, bringing high elevation snow and low elevation rain to the Wasatch region.  However, changes will arrive on Tuesday as the next organized low pressure system moves across Utah, spreading much colder air into the state with rain changing to snow in Salt Lake City.

Several inches of accumulation will be possible across the Salt Lake City area from Tuesday afternoon through Wednesday, while flash freezing of previously wet roads will be of concern Tuesday evening.

The image below shows this morning’s upper level pattern – we can see a trough of low pressure center just off the Pacific Northwest Coast in Washington (image source: College of DuPage).

 

 

This low pressure system is moving from north to south down the West Coast and transporting cold air southward along with it.  This pattern is actually producing snow across the Seattle area this morning.

This low pressure system and colder air will eventually swing eastward into the Great Basin and into Utah on Tuesday.  Temperatures will remain warm enough overnight tonight for precipitation to remain as mostly rain across the Salt Lake City area, before a cold front arrives Tuesday morning with high temperatures peaking early in the day.

By Tuesday afternoon, we can see the low pressure system is located over the Great Basin and moving into Utah (image source: Colorado Avalanche Information Center).

 

 

Look for a rain/snow mix Tuesday morning for Salt Lake City, before transitioning to all-snow by around noon or shortly after.  Good melting is expected initially with snow that falls Tuesday afternoon, but by late afternoon or early evening, snow will begin to accumulate on all surfaces as temperatures fall below freezing.

In addition, roadways will likely become icy Tuesday evening and overnight as previously wet roadways freeze up.  Temperatures overnight will fall into the low/mid 20s across the Salt Lake City area.

Snow will continue to fall at times (mostly at light to moderate rates) overnight Tuesday and continue well into the day Wednesday, before tapering off Wednesday evening.  Temperatures will likely remain in the 20s for Salt Lake City during the day Wednesday with snow accumulating on roadways.  The Wednesday morning commute will be impacted the most, especially with icy conditions expected under new snowfall from previously wet roads freezing over.

Models are somewhat variable on snowfall amounts with the NAM model coming on a little bit lower, but this seems to be an outlier while the European and American GFS Models are coming in a little higher.  While this is a low resolution model, the GFS image pictured below (image source: pivotalweather.com) is generally in line with our thinking.

 

 

Overall, we expect snowfall totals will most likely end up in the 3-6″ range for Salt Lake City down to Provo, with higher amounts for the benches near the Wasatch Foothills, and lower amounts farther north from Ogden to Brigham City (although Logan is probably closer to what SLC receives).

Following this storm, a chilly airmass well settle into the region on Thursday and Friday before the next system approaches this weekend.

 

Colorado High Country Snow

NWS has issued a Winter Weather Advisory for the Central/Northern Rockies above 8,000ft until 6:00PM February 3, 2019

NWS has issued a Winter Storm Warning for the San Juan region above 8,000ft until 6:00PM February 3, 2019

A strong system is making its way into western Colorado today bringing snow all along the Colorado High Country.  Most areas will see snow, with the San Juan range getting the most out of this system.  Areas to the north should see amounts between 3-6″ with 6-12″ possible at higher elevations.  Areas south should see anywhere from 4-8″ with higher elevations receiving over a foot of snow!  

These are great conditions for skiing as there will be fresh powder throughout the Colorado High Country today, but travel conditions could be hazardous at times especially on mountain passes where heavy snow and gusty winds could cause white out conditions at times.  Remember to have any necessary equipment, such as snow tires, chains, or all wheel drive when traveling in these types of conditions in Colorado’s High Country since failure to do so can result in being ticketed!

A look at total snow expected per NWS Forecast:

Complex pattern with several days of snow ahead for Northern Rockies

Following a dry week across the Northern Rockies, the pattern will turn much more active over the weekend and into the first half of next week as a series of Pacific troughs move into the Western U.S.  This pattern will actually be rather complex with a variety of impacts across the region as warm Pacific air from the southwest battles with cold arctic air pushing southward into Montana.

The approaching trough of low pressure is still located well off the coast of California this morning, but significant moisture ahead of this trough can be seen streaming across the western states from south to north in this morning’s water vapor satellite image (source: NOAA).

 

 

The southerly source of this Pacific moisture will result in wet/dense snowfall at the start of this storm cycle, along with mixed precipitation or rain in many of the valleys.  Moisture will arrive for most areas west of the Continental Divide during the day on Saturday, with the heaviest precipitation expected across Idaho and Western Wyoming Saturday night.  Warm air in place will keep this a rain/snow mix for areas such as Jackson Hole and Ketchum/Sun Valley with significant travel impacts likely limited to mountain passes and areas above the valley floors.

The next image shows the approaching trough of low pressure by 5pm Saturday, as projected by the GFS Model (image source: tropicaltidbits.com).

 

 

More snow is expected region-wide from Sunday through Wednesday as a second trough of low pressure moves across the area early next week.  Also, an arctic cold front will push into Western Montana on Sunday morning, before stalling along the Continental Divide.  This will result in much colder temperatures and higher road impacts due to snow across the Bozeman area on Sunday.

A variety of impacts can be expected over the next several days as follows, and are subject to change given the complexity of this pattern.

Missoula:  Cold air will push in from the north/northeast on Sunday morning, combining with Pacific moisture to result in the potential for respectable snowfall amounts and travel impacts.  This area is in a tough spot, however, as arctic air sometimes doesn’t push as far west as the models show, in which case snowfall could be less than forecasted.  However, the prime times for travel impacts (assuming meaningful snow does occur) will be Sunday morning and Sunday night/Monday morning.

Bozeman:  Snow will arrive Sunday morning and continue off and on for the next few days with arctic air in place, clashing with Pacific moisture.  Temperatures will fall well below freezing behind the arctic front Sunday morning, and therefore roads will quickly become snowpacked on Sunday with continued travel impacts expected through Wednesday.  Snowfall amounts Sunday-Monday will likely be in the 3-6″ range, with additional accumulations likely on Tuesday and Wednesday.

Jackson Hole:   Borderline temperatures will result in a rain/snow mix Saturday and Saturday night.  Colder air aloft should allow for mostly snow in the valley on Sunday, but temperatures will still be warm enough that travel impacts should be limited in the valley (unless heavy snowfall rates overcome borderline temps Sunday morning). 

We should gradually see colder temperatures filter in Sunday night and Monday, with better snow accumulation potential in the valley along with travel impacts.  The cooling trend will continue as periods of snow persist on Tuesday and into Wednesday, with each day seeing progressively higher travel impacts.  Travel conditions over Teton Pass will be very difficult throughout the period as significant snowfall is expected from Saturday through Wednesday.

Ketchum/Hailey:  Similar to Jackson Hole, warm temperatures will keep travel impacts limited across the valley areas on Saturday and into the first part of the day Sunday, before gradually colder temperatures filter in by Sunday evening with heavy snowfall and more significant travel impacts likely.  Monday and Tuesday will see continued periods of lighter snowfall, but with colder air arriving travel conditions will remain difficult.

Idaho Falls/Pocatello:  This will be mostly a rain event over the weekend due to warm temperatures, but we could see some light snow impact the area by Tuesday-Wednesday next week as the last trough passes through the area along with colder temperatures.

Snow returns to Chicago tonight with impacts for the Monday morning commute

A low pressure system approaching from the northwest will bring the next round of winter weather to the Chicago metro area from late tonight through Monday morning.  Looking at this afternoon’s water vapor satellite image, we can see moisture from this approaching system currently pushing into Minnesota and Iowa (image source: College of DuPage).

 

 

This will be a fast-moving but potent system with about 6-8 hours of heavy snowfall expected overnight.  The heaviest period of snowfall will be from about midnight through sunrise with snowfall rates of 1″/hour or higher expected at times.  The next image from the HRRR model shows the projected radar reflectivity at midnight tonight, with widespread snow filling in across the Chicago area (image source: College of DuPage).

 

 

Snow that falls will easily accumulate on all surfaces given the cold temperatures in place.  However, it should be noted that a significant warming trend will occur overnight as warm air pushes in from the south.  Temperatures will rise from the low teens at around midnight tonight into the low 30s by mid-morning Monday. 

Toward the back edge of the main area of precipitation Monday morning, we could even see precipitation briefly change to light freezing rain, before a cold front arrives and temperatures quickly drop again.  Lingering scattered snow showers will continue through the day Monday, but most of the accumulation will occur overnight.

Total snowfall amounts across the greater Chicago area overnight are likely to range from 4-7″ for most areas, with significant road impacts expected during the Monday morning commute.  Heavier precipitation and colder air with higher snow to liquid ratios will exist farther north, so across the northern suburbs to the Wisconsin border, snowfall amounts look to be more in the 5-10″ range.

In addition to snowfall, winds will be gusty from the south at 15-25mph with gusts to 30mph overnight through Monday morning, becoming northwesterly with similar speeds Monday afternoon.  As a result, areas of blowing and drifting snow can be expected.

Following this storm, a well advertised blast of arctic air will arrive with record cold temperatures expected for the middle part of the week, including dangerous wind chills.

Colorado Snow Pack Improving!

Heavy mountain snow over the last month has really helped out Colorado’s snow pack, especially in the southwest area along the San Juan mountain range.  Previously SWE (Snow Water Equivalent), what is used to monitor Colorado’s drought, totals were around 70% for the San Juan mountain range indicating drought like conditions since there has been very little snow that has fallen early this season in and around that area.  Fortunately that has changed recently and the southwest region is close to 100% of average for snow pack from a multitude of strong storm systems that have dumped beneficial snow over the region.  This has raised Colorado to 109% statewide and is the first time Colorado has been over 100% total SWE this season! 

For reference, here is the snow pack from earlier this month with statewide SWE at 95%:

Current as of 1/25/2019 statewide SWE at 109%:

 

 

Heavy snow for Madison and Milwaukee on Sunday night

A potent Alberta clipper system will drop southeast out of Canada on Sunday night, bringing a round of heavy snowfall to the Madison and Milwaukee metro areas during the overnight hours.  The timing of the snowfall will result in significant travel impacts during the Monday morning commute.

This fast-moving system is located way up in the Canadian Rockies as of early Saturday evening, but will quickly moves south into the Northern Midwest during the day on Sunday.  By Sunday night, we see the surface Low approaching from the west, at which point some of the heaviest snow will be falling (image source: pivotalweather.com).

 

 

Look for snow to reach the Madison and Milwaukee areas by early evening Sunday, before really picking up later Sunday night with the heaviest snow expected between about midnight Sunday night and sunrise Monday morning.  The next image shows the NAM Model projected radar reflectivity, with snow filling in across the area Sunday evening (image source: College of DuPage). 

 

 

Southerly flow ahead of the low pressure center will transport warm air aloft into south central and southeast Wisconsin during the overnight hours – or what meteorologists refer to as “warm air advection”.  This will act to enhance precipitation rates, with 1-2″/hour snowfall rates expected at times during the overnight hours across Southern Wisconsin.

The advancing warm air aloft will also have impacts on surface temperatures, with a significant rise in temperatures during the overnight period.  In Madison, temperatures are expected to rise from the upper single digits Sunday evening into the mid to upper 20s by Monday morning.  In Milwaukee, temperatures are expected to rise even higher into the low 30s by Monday morning, with perhaps a brief period of time with sleet and/or freezing rain mixing in.

The advancing warm air will make snow-liquid ratios a tricky forecast, and any mixed precipitation could potentially cut into snowfall totals across the Milwaukee area.  Regardless, this will still be a high impact even through Monday morning with difficult travel conditions. 

Most models are in general agreement with precipitation amounts with this system.  Overall, snowfall totals are likely to range from 6-10″ from Madison to Milwaukee.  The image below is one model’s projected snowfall totals through Monday afternoon (image source: pivotalweather.com).  Notice this particular model projects even heavier amounts up toward Appleton, Sheboygan, and Green Bay.  This likely is a result of potential lake enhanced snow due to southeast winds, as well as colder air farther north leading to higher snow-to-liquid ratios.

 

 

Light to moderate snow showers will continue through much of the day Monday, with temperatures quickly falling again after Monday morning’s brief warm-up, as a cold front moves through around mid to late morning.  Gusty NW winds behind the cold front during the day Monday will add to the travel problems by result in blowing and drifting snow.  In addition, if any melting occurs around Milwaukee on pavement Monday when temperatures briefly warm up, it will quickly turn to ice again by later Monday as temperatures drop.

Following this potent storm system, the bottom will really drop out this week as a powerful surge of arctic air arrives, plunging temperatures to near record levels through the middle of the week.  High temperatures on Wednesday are likely to remain well below zero region-wide.

Significant snow for Twin Cities Sunday night, followed by brutal cold

A strengthening Alberta clipper system will track from NW to SE out of Canada and into Central Minnesota on Sunday, which should result in the biggest snow event of the season so far for the Twin Cities.  All of the ingredients are coming together with this storm, including abundant moisture, favorable upper level dynamics, and very cold air aloft to result in high snow-liquid ratios.

The image below shows the NAM-model projected upper level pattern for Sunday evening, which clearly shows the trough of low pressure moving into southern/central Minnesota (image source: pivotalweather.com).  This is a favorable storm track for Minneapolis snow.

 

 

 

Snow will begin to move into the Minneapolis-St. Paul area by mid-afternoon Sunday as the surface low pressure center nears the Canada/North Dakota border, as projected by the NAM Model (image source: College of DuPage).

 

 

Look for snowfall to quickly pick up during the evening and overnight hours, falling heavily at times.  The heaviest snowfall rates are generally expected between about sunset Sunday evening and 3am Monday.  Temperatures will be very cold with this system, which will result in a variety of impacts.  With surface temperatures in the single digits, snow will easily accumulate on roadways throughout the event.

In addition, the cold layer of air aloft will result in very efficient snowfall production, meaning high snow to liquid ratios.  In other words, it will not take as much liquid precipitation to produce a given amount of snowfall as usual.  During a wetter snowfall event, snow to liquid ratios are usually near 10:1 (meaning 1″ of liquid = 10″ of snow), but for this event we are likely to see snow to liquid ratios approaching 20:1.

Bottom line, it looks like we will see widespread snowfall amounts in excess of 6″ across the Twin Cities, with most areas likely ending up in the 6-10″ range.  Given the high snow to liquid ratios, this will also be a very dry, powdery snowfall.  The image below shows projected snowfall amounts from the NAM Model across the Northern Plains (image source: College of DuPage), which are generally in line with our thinking.  Models are actually in strong agreement with this system, which adds a degree of confidence to the forecast.

 

 

Snowfall rates should be decreasing by sunrise on Monday, but given the significant amount of overnight snowfall, significant travel impacts can be expected for the Monday morning commute.  Winds will not be excessive with this event, but moderate breezes from the SE at 10-15mph Sunday night, and NW at 10-15mph on Monday could result in some areas of blowing snow, given the powdery nature of the snowfall.

Lingering light snow showers will remain possible into early Monday afternoon, before an extreme blast of arctic air arrives behind this system.  Some models are projecting temperatures in Minneapolis-St. Paul to fall to 30 below or colder by Wednesday morning, which would tie or break a record low for the day.  In addition, gusty winds Tuesday night/Wednesday morning are expected, which will result in excessively low wind chill values. 

While snowfall Sunday night will result in plenty of work on Monday morning as far as snow removal goes, school districts and other organizations should prepare for the growing likelihood of dangerously cold temperatures and wind chills for the middle part of the week.

 

 

Extended cold snap for Minneapolis through the end of January

It’s been a mild winter so far across the Twin Cities, but we’ve already started to see changes over the past several days with the first subzero temperatures of the season occurring on the 18th and 19th.  The pattern is now setting up with high pressure over the far Western U.S. and a deep trough of low pressure over the Central/Eastern U.S., which will allow for cold arctic air to pour into the northern plains.

The next strong arctic cold front will be arriving Thursday morning across the Twin Cities.  By 9pm this evening, we can see the arctic cold front (along with subzero temperatures) pushing into North Dakota and advancing toward Minnesota (image source: College of DuPage).  The lines that are close together are called isobars (lines of equal surface pressure), and the leading edge of these tightly wound isobars indicate the approximate position of the cold front.

 

 

Looking at the same model, we see the cold front has pushed through the Twin Cities by 9am Thursday with temperatures falling below zero (image source: College of DuPage).

 

 

The cold weather looks to stick around for a while.  The next image from the GFS model shows projected temperature anomalies over the next 5 days (image source: tropicaltidbits.com).  High temperatures for Minneapolis-St. Paul are only expected to be in the single digits most days during this time frame.

 

 

As far as snow chances go, the pattern will remain mostly dry through the end of the week.  However, the next chance of meaningful snow is currently projected to arrive Sunday night as a potent upper level disturbance arrives from the northwest.  While the exact track remains uncertain, the potential exists for meaningful snowfall across the Twin Cities.  The image below from the GFS model shows the upper level heights and wind pattern for Sunday night, and we can see the location of the disturbance clearly over the Dakotas and Minnesota (image source: pivotalweather.com).

 

 

For now, it would be a good idea to start thinking about Sunday night and Monday morning as possible high impact times for road travel, and of course staying tuned as the forecast evolves.

Following Sunday night’s potential storm, more cold air will arrive – possibly even colder than what will be experienced late this week.  The next image from the GFS shows projected temperature anomalies for the 6-10 day timeframe (image source: tropicaltidbits.com).

Northwest flow system to bring snow to Northern Rockies

A potent upper level disturbance arriving from the northwest will bring moderate to heavy snow to portions of the Northern Rockies from late tonight through Wednesday, favoring Western Montana, NW Wyoming, and Eastern Idaho.  Areas to see high impacts from this event include Missoula, Bozeman, and Jackson Hole.

This evening’s water vapor satellite image shows moisture from the advancing disturbance over the Pacific Northwest (image source: NOAA).

 

 

 

Snow will begin to fill into the region tonight with up to a few inches of snow expected across the valleys of Western Montana and Western Wyoming through daybreak tomorrow.  Cold air is in place ahead of this system, especially from Bozeman south to Jackson, and this will result in snowpacked roads for the morning commute on Wednesday.

The heaviest snow with this system is expected during the daytime hours Wednesday as the core of the disturbance and best upper level dynamics move across the area.  The RAP-model projected upper level heights and winds pattern illustrates this disturbance well as it moves across the Idaho/Montana/Wyoming region around midday Wednesday (image source: pivotalweather.com).

 

The next image shows the RAP Model’s projected snowfall (using the Kuchera method, which estimates snow-liquid ratios) from tonight through 5am Thursday.  While a single model’s snowfall projection can never be taken verbatim, it does give a general idea of snowfall amounts and distributions region-wide (image source: College of DuPage). 

We can see here that some of the highest snowfall totals with this storm are expected across the Bitterroot Range along the ID/MT border, the Gallatin and Madison Ranges in SW Montana, and the Teton Range in Wyoming.  This makes sense given the northwesterly storm track.

Here are some of the impacts expected across the area:

Missoula:  Most of the snow will fall between midnight tonight and mid-afternoon Wednesday with the heaviest snowfall rates between about sunrise and noon.  Snowfall will impact the morning commute with snow accumulating on roadways, while some melting is likely Wednesday afternoon as temperatures rise above freezing.  Snowfall amounts for Missoula are expected to be in the 3-6″ range, while in the surrounding mountain ranges totals in excess of one foot are possible.

Bozeman:  This pattern is favorable for significant snowfall amounts in the Bozeman area, with light snow filling in overnight and impacting the morning commute with cold temperatures in place.  However, the heaviest snow is expected from about mid-morning through early evening with road impacts expected throughout the day, including a challenging evening commute.  Total snowfall amounts are expected to be in the 4-8″ range for Bozeman, with amounts in excess of one foot across the surrounding mountain ranges.  Significant travel impacts are expected over the mountain passes, especially Wednesday evening.

Jackson Hole:  Steady snowfall will develop after midnight tonight and continue through about midnight Wednesday night.  Cold air will be locked in place across this region, yielding higher snow-liquid ratios and resulting in high impacts on the roads, both for the Wednesday morning commute and especially for Wednesday evening travel.  Total snowfall amounts will likely range from 3-6″ in the Jackson valley, with isolated higher amounts possible in the northern valley and near the base of the Tetons.  Snowfall amounts in the Teton Range could exceed one foot in some areas, with significant travel impacts expected over Teton Pass, especially Wednesday evening.  Gusty winds from the west could also create blowing/drifting snow, especially over mountain passes and across the open valleys of Eastern Idaho.

Idaho Falls/Pocatello:  Only light snowfall amounts are expected across this region, generally in the 1-2″ range.  However, strong winds can be expected Wednesday afternoon and evening, resulting in areas of blowing snow and poor road conditions. 

Heavy snow for parts of Iowa and Wisconsin today

A fast-moving storm system located over Eastern Colorado this morning will quickly move across the Central U.S., bringing a round of winter weather to the upper plains with locally heavy snowfall amounts expected across Northeast Iowa and Southern Wisconsin.  Precipitation will also start as light freezing rain across Central Iowa this morning, before transitioning to snow this afternoon, which will make for very difficult travel conditions.

This morning’s weather analysis shows the upper level low pressure system near the Colorado/Kansas border this morning (image source: College of DuPage).  

 

By this evening, we can see this trough of low pressure has moved northeast into Iowa per RAP model projections, with strong upper level dynamics acting to enhance precipitation across Iowa and Wisconsin (image source: pivotalweather.com).

 

Shallow moisture in place across Central Iowa will result in some light freezing rain or drizzle this morning, with temperatures in the teens/low 20s.  This will make for treacherous travel conditions initially.  By this afternoon, we’ll see moisture spreading into the area with snow developing across Iowa and Southern Wisconsin (including areas that were previously freezing drizzle).  The next image shows the HRRR-projected precipitation type radar for 2pm central time this afternoon (image source: pivotalweather.com).

 

 

Notice the sharp precipitation type transitions the farther south you go.  Chicago will actually start out as freezing rain this afternoon, but warmer air arriving from the south will result in a transition to all-rain this evening for the Windy City.

The heaviest snow with this system will fall from Northeast Iowa across Southern Wisconsin, including Des Moines, Cedar Rapids, Madison, and Milwaukee.  Many areas in this corridor could see snowfall totals of 6″ or more from Tuesday afternoon through Wednesday morning, with isolated higher end totals of 10″+ possible.  Farther north, the Minneapolis-St. Paul area will be a bit too far north to see significant snowfall, with only minor snowfall totals expected here during the daytime hours Tuesday.

The next image shows one model’s projected snowfall totals across this region (image source: pivotalweather.com).  While this shouldn’t be taken verbatim, it should give a good general idea of where and how much snow will fall across the area.

 

 

The highest snowfall rates across Iowa/Wisconsin are likely during the evening/overnight hours as the strongest upper level dynamics move across the area.  Temperatures will be in the low 20s/upper teens throughout this event in the aforementioned areas, so snow will easily accumulate on road surfaces.  The Tuesday evening commute and Wednesday morning commute will be significantly impacted across larger metro areas such as Des Moines, Madison, and Milwaukee.

In addition, gusty north/northwest winds will develop overnight and into Wednesday morning (strongest across Iowa), which will result in areas of blowing and drifting snow.