Take Your Pick: Waves of rain-sleet-ice-heavy snow & thunder next 48 hours

Something for Everyone?

I'm sure there are still a few Minnesotans who are joyful at the prospect one more major wintery blast of precipitation this week.

I just can't count myself in that group. I'm still looking for an escape hatch.

So I offer this brief diversion. Cherry blossoms at peak in Washington D.C this spring.

Image: National Cherry Blossom Festival

As I battle my own "winter denial" the professional part of my brain looking at the weather maps feels like a cold slap in the face.

It's going to snow (heavily) in April. It happens sometimes in Minnesota. Get over it.

If you're in the "more winter please" crowd there is something for everyone in the forecast.

The next 48 hours will bring rain, sleet, ice, snow and even some thundersnow to parts of Minnesota.

And let's be clear. This could be a record setting, even crippling April snowfall event for much of southern Minnesota.

High winds may snap snow and ice laden trees and power lines in southern Minnesota, and power outages are likely tonight through Thursday.

How much?

Details below in the blog... but let's put it this way. It's not out of the question as some modles suggest that the metro may end up with a top 5 (9.6")...or even a shot at the biggest April snowfall on record (13.6") by Thursday evening.

In other (more hopeful) news...it will gradually warm up this weekend, and we'll be slowly melting the snow that falls this week.

And spring will come...eventually.

Winter Storm Warnings include the metro

Ice Storm Warnings include Worthignton and southwest Minensota

Next Wave Overnight: Thunder south

Wave #1 Tuesday brought snow to southwest Minnesota and another .32" rainfall to MSP Airport.

Wave #2 of our multi-part fuel injected storm system blows through overnight with a mixed bag of rain/sleet/ice snow and yes...thundersnow in southern Minnesota.

The rain snow line should set up right in the metro overnight. That could produce a couple inches of heavy wet snow from the (especially the west) metro and points west by morning.

[image]

-Latest Twin Cities radar loop with precip type

Earlier severe thunderstorms rumbled through northern Iowa near Mason City Tuesday evening.

557 PM CDT TUE APR 9 2013

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHWESTERN WRIGHT...SOUTHWESTERN HANCOCK...NORTHEASTERN HUMBOLDT AND SOUTHEASTERN KOSSUTH COUNTIES UNTIL 630 PM CDT...

AT 554 PM CDT...A SEVERE THUNDERSTORM WAS LOCATED 8 MILES NORTHEAST OF DAKOTA CITY...AND MOVING NORTHEAST AT 45 MPH.

HAZARD...QUARTER SIZE HAIL.

SOURCE...TRAINED WEATHER SPOTTERS. QUARTER SIZED HAIL WAS REPORTED UST WEST OF HUMBOLDT.

IMPACT...DAMAGE TO VEHICLES AND CROPS IS EXPECTED.

Check out the 2km visible satellite shot from late Tuesday afternoon. You can see the broader snoother clouds with "stratiform snow" in South Dakota. You can alos see the lumpy "convective clusters" with thunderstorms in Nebraska and Iowa.

Image: College of DuPage

Preview of coming attractions?

The drought of 2012 afforded us a quiet severe weather season last year. With our more active "spring" weather pattern so far this year it's a safe bet...likely a no brainer that we'll likely see a more active severe weather season in 2013.

Severe weather is likely in the heart of Tornado Alley overnight into Wednesday.

Meteorology 101: Big temp contrast = Big Storm

Take a look at the incredible temperature contrast across the Upper Midwest Tuesday. I saw 80s in southeast Iowa....and 20s in northwest Iowa and teens in Nebraska.

This kind of wicked temperature contrast fuels big, wrapped up, super charged Midwest storms.

Break Down:

The late Tuesday models confirm previous thinking on the still incoming system.

Here's the best brief breakdown at this point.

Overnight & Wednesday:

The next wave of precip blossoms northward through southern Minnesota and the Twin Cities.

Temps a few degrees either side of the freezing mark in the metro and south will mean a mixed bag of rain, ice sleet & snow. There will be some accumulations on your lawn by morning...and some glaze ice on driveways trees & power lines.

In southwest Minnesota...a full blown ice storm with icy accumulations between .25" and .75" is likely. There could be some serious power outages by Wednesday afternoon.

Main Event: Wednesday Night & Thursday:

As the strong upper low approaches Wednesday evening, a powerful "vacuum effect" will produce serious "lift" in the atmosphere over southern Minnesota.

Mixed precip will become all snow, and strong "lift" will produce heavy snow bands...and possibly thundersnow. All indications are snowfall rates could reach 1" to 2" per hour in this "dynamic" environment.

The heaviest snow should fall between about 10pm Wednesday night and noon Thursday. If the 12+ hours of moderate to heavy snow materializes...we should have no problem reaching snowfall output of 6" to 12"+ for central and southern Minnesota...including the Twin Cities.

Many of the models suggest higher totals. I'm still being conservative at this point given the season, warm ground and the potential for compaction. A few inches of "what falls" will melt and comapct...that means what's in your yard may be a few inches less than what falls fromt he sky.

The Perfect Storm?

One scenario is still possible, if unpleasant to think about.

If everything comes together just right Wednesday night & Thursday...the more aggressive forecast models may be on to something with the suggestion of prolific snowfall totals.

The possibility of some 10" to 20" snowfall totals seems laughable in April, but so did the thought of 28" snowfall before the Halloween Mega Storm.

This is one powerful storm. It has all the ingredients to produce heavy snowfall totals with thundersnow that could cause "snow bursts" capable of 2" to even 3" per hour in some areas Wednesday night & Thursday.

It may sound "Snowpacolyptic"... but at this point I can't rule out the slim possibility that this storm slows down and intensifies enough to produce some 15" to 20" April snowfall totals in the southern half of Minnesota...and possibly the Twin Cities by Thursday night.

Full disclosure: Here are the NAM & GFS snowfall outputs for MSP Airport as of Tuesday PM.

NAM:

GFS:

Just thought I'd throw that out there.

Stay tuned.

PH