Saturday, March 11, 2017

You Didn't Really Think Winter Was Over, Did You?

When temperatures spiked to 73 in February, did anyone actually believe winter was over?  Oh, you did?  Ha!

A major winter storm will impact the region beginning Tuesday morning.  Confidence in a storm is high but the ultimate track is still being worked out.  There is a high probability of double-digit snow totals for everyone except South Coastal New England.  The final track will likely bring some mixed precipitation/rain to these areas.    They hit the jackpot yesterday as many locations near the South Coast and over to the Cape and Islands reported over 6" snow Friday.  A full list can be found here.
NWS Boston Observed Snow Totals 
Temperatures this morning bottomed out at 6 in Worcester, 10 in Boston and Hartford, and 14 in Providence.  These fall short of record territory but they will set the stage for potentially the lowest high temperature on record for the date.
Current forecasts do indeed break or tie the low max temperatures today.  Worcester will struggle to get back to 15-16 while Boston should get into the low 20's, but no higher than 22.
NWS Max temp forecast Saturday.  Potential record low max temps circled (image Weatherbell)

 One does not need to be a meteorologist to know that it is nasty outside today.  The winds are howling out of the Northwest making a mess of the snow that did fall yesterday.  Wind chills are forecast to remain below zero most of the day.  A *Wind Chill Advisory* has been posted for Northern Worcester County until 10 AM.  A wind advisory may go up this afternoon for wind gusts over 40 MPH.
NWS Saturday AM Headlines
Low temperatures tonight will fall into the single digits.  Worcester and Providence are currently forecast to break/tie their record low temps for the date.  The wind should lessen a little tonight but it will still be very cold.
NWS min temperature forecast Sunday.  Potential record low temps circled (image Weatherbell)
Now let's turn our focus to the real reason you are here for this blog.

Medium Range Forecast
Here is the forecast surface map tomorrow at 8 AM.  Notice the dome of high pressure in Central Canada, the storm coming through the Northern Rockies, and the mess along the Gulf Coast.
WPC Surface Fronts/Precipitation Sunday 8 AM
While high temperatures remain in the 20's in Southern New England tomorrow, the Southern and Northern branches of the jet stream will send energy on a journey that is destined to meet up near the East Coast.  At 8 PM tomorrow night the upper air chart does not look all that impressive.
00z ECMWF 500 mb height anomaly Sunday 8 PM (image Weatherbell)
You'll have to look closely, but there is a notch of upper atmosphere tracking through the Dakota's and another just to the east of Florida.  By Monday morning there will be snow across Illinois and Indiana spreading east into the Ohio Valley.
WPC Surface Fronts/Precipitation Monday 8 AM
By Tuesday AM the energy will combine off the Mid-Atlantic coast forming a large and powerful Nor'easter.  A new upper atmospheric low will close off in the Great Lakes, effectively capturing the new surface low that develops near the Delmarva.
00z ECMWF 500 mb height anomaly Tuesday 8 AM (image Weatherbell)
Here what this looks like at the surface (500 mb is about 18k ft).
WPC Surface Fronts Tuesday 8 AM
As we enter the middle of March, the sun angle plays a big role in accumulation.  This storm is strong enough to overcome the physical limitations that are naturally placed a Spring snowstorm.  That said temperatures in SE MA will be near freezing.  That means some sleet/rain can mix in for a time.  Temperatures look to be in the upper 20's once you get into Central/Western Southern New England.

I'm still working on snow totals, I'll have something out tomorrow.  But you can probably imagine what a major nor'easter that is pretty much all snow will deliver.  Tomorrow I may declare this a "Bread, Milk, and Alcohol" type snowstorm.  If you plow, get ready for a long shift.  If you teach. have a backup plan for Tuesday/Wednesday lesson plans.

So yeah, winter is not over.

- I don't think this is likey, but I can't ignore what some of the computer guidance is suggesting today.  A track over Southern New England would deliver something like this

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