Fresh Snow in Cali. Mild Temps Next Week.

Last week’s installment touched upon the fight we usually see in March between lingering cold to the north and advancing spring warmth from the south.  The fight usually takes the form of storminess, where it only a matter of whether there is enough cold air in the mix to produce snow instead of that other stuff.  And yet here we are in the first week of March with something resembling a mini snow drought over the eastern half of the country.  There hasn’t been a significant widespread snowfall in a couple of weeks and aside from northern New York and northern New England, where there have been one or two light snowfalls across in recent days, surfaces have morphed into “machine groomed” or, when temps rise above freezing, “loose granular.”  Fear not, though.  I hoped that a storm late this week would turn the corner and hit the Northeast, but a cold northwesterly flow has suppressed that idea well to the south.  By no means has the East seen its last snowfall, but the next sizable one will come after a turn to milder weather during the week of the 8th.  Here is a forecast for the jet stream level on the 11th that illustrates the cause of the warm-up.

If you follow the lines around the burnt orange center in a clockwise fashion, you can see that the air mass that flows into locations east of the Mississippi originates over the Southwest, where temperatures are running above normal.  At the same time stamp, the following surface map shows a high pressure center off the coast of New England.

Following the lines clockwise around the blue “H” indicates a broad, low level mild southwesterly flow reaching the Great Lakes to New England.  So, look for a shift to softer, spring-like surfaces in these areas next week.

The flip side of these ridges at the surface and aloft are the upper troughs and surface low centers that will be moving through the West next week.  The air flow is around troughs is counter clockwise, and if you look at the first map and picture the western trough sliding down the coast from Washington to southern California, you can see that a broad onshore flow of moisture will immediately precede the arrival of the center of circulation, which is a great recipe for fresh snow in the Cascades and Sierra ranges.  The highest totals will come from central and southern Sierra resorts, where the core of the trough will pass overhead midweek. Farther north it will be offshore.  Later next week, the weakening trough will swing through the southern Rockies, where lighter snow will fall but refresh surfaces.

Back to the East.  The pattern is progressive, so the warming will be transient.  Here is a jet stream forecast for the 15th that shows a cold trough returning to the Midwest and East.

That setup will help preserve snow and produce fresh snow at times and there are signs that the colder pattern will dominate the second half of the month.  More on that next week.

REGIONAL HIGHLIGHTS:

Pac NW/B.C.:

After a heavy late week dump in B.C., lighter snows fall this weekend in the Cascades.  Periodic light snows during the week of the 8th.

Central and southern Sierra:

Fresh snow as well as wind this weekend for Tahoe.  Snowy much of the week of the 8th for all Cali resorts.

Rockies:

Turning colder next week with light to moderate snows across the north.  Weakening upper trough brings light midweek snows in southern Rockies.

Midwest:

Seasonably cold weekend and milder next week.  Best shot at snow later next week across far northern Minnesota and Michigan.

Northeast:

Cold weekend with temps moderating by midweek.  Transition back to colder pattern gets underway next weekend with potential messy storm.

Mid-Atlantic/Southeast:

Midwinter temps this weekend; spring skiing develops next week.  Colder air returns week of the 15th.

 

 

One Comment

  1. Avatar Dave Prince says:

    Hi Herb.. Cannon was icy Wednesday, much much better Thursday after a great grooming job. For better or worse, planning Sunday River next Wednesday with a helicopter buddy of mine. Care to join us? Take care. dp

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