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December 29, 2012 Snowstorm info

 

A northern stream and a southern stream which ended up enteracting. A low off the coast which ended up bombing out with a positive NAO. A storm which eventually ended up a sub 980mb.  A low over Ohio Valley which ended up  transfering to the coastal low of the Virginia coast. A storm which slowed down just enough and a storm which came in 25 miles closer than once projected by models. A path over Atlantic waters running around 47 degrees which is higher than the 42 degree normal. A storm which was supposed to have 1/4 – 1/2″ ended up producing up to 1″ liquid in spots. And cold air which hung around more led to a 6-12″ snowstorm rather than a 2-4″ snow event.

Luckily for the short term models such as SREF, HRRR, RAP & RUC we were able to see these changes 6-10hrs before hand. But before that there were no indications that anywhere was getting 10-12″ of snow especially in Connecticut.

So lets go through some stuff..

Pressure1

 Here’s the Pressure map from NOAA. Saturday 8am December 29, 2012. Low over PA about to transfer energy to the coastal low coming up the coast.. Was snowing in PA and western NY at this time.

 

 

 

Pressure2 

 

 

Here’s Saturday 1pm, the transfer was made off the Virginia coast and the storm was a 996mb low. At this point it was snowing across the region except for south of central NJ and Long Island. Even parts of coastal CT had a mix and/or rain happening at this point.

 

 

Pressure3

 

 Here’s the storm at a 984mb low just inside the benchmark southeast of eastern LongIsland. At this point it pretty much ended for PA, NJ, NY and western half of CT but the heavy snows were coming into Eastern half of CT, Rhode Island and southeastern MA. Mixing and rain along the capes prevented big accumulations there but Rhode Island and Boston metro got 3-8″ around there and the highlight of this storm came in the Eastern half of CT where snow accumulations ranged from 7-12″ which local parts of MA did as well.

Map138

 

This was the radar, temps, SLP & winds at 5000 feet at 3:40pm You can see the surface temps around Atlantic City were upper 30s and low 40s in Delaware. Even though winds were from the west the 850mb temps also didnt support snow in those locations. I was impressed that even with a south flow above, the cold air hung on at the CT coast. There really wasnt a lot of warm air being “pushed” up with this storm but those who were warm at the surface had trouble cooling down.

 

 

 

 

 

Map3

 

 

 This was the radar, temps and SLP at 7pm. The pinks are 35-45dbz band. It was a wall of white heading into the shoreline of CT and parts of MA. 984mb low sitting southeast of Long Island

 

 

Map4

 

 

 Saturday 11pm Hurricane force winds at 5000 feet East of the center of the storm. SPC puts out a Heavy Snow Meso discussion for southern Maine. Storm moves towards Nova Scotia.

 

 

 

 

Map2

 

 

 

 Sunday morning a 970mb low near Nova Scotia. Cold and Windy conditions for the entire NorthEast. 

 

snowtotal 

From Eastern Region Headquarters a countour look at the snowtotals across the NorthEast.

 

 

 

 

 

snowTotals 

 

A closer look with the reports listed.

 

 

 

 

HPC12/29/12 

 

 

Here’s a look at HPC’s track day of.

 

 

 

 

Pressure4

  This is a look at the levels of the atmosphere. Bascially all levels were lined up except the 500mb but as soon as the 850mb transfered to the coast the storm began to bomb out and temps began to drop at the shoreline as the 850 layer dragged in the cooler air. This was the 4pm timeframe. For NYC southward we want to see the 850mb level transfer much south then it did here which was at the Pennsylvania/New Jersey Latitude. Had it happened around Delaware or Virgina there would be more snow reports from Baltimore/Philly metro.

 

 

SnowCover

 

 

 

According to NOAA.  99.3% of the NorthEast has snowcover. The outer capes of MA didnt get accumulations..

 

 

 

RECORDS FOR DECEMBER 29 SNOWSTORM:

 A RECORD SNOWFALL OF 4.4 INCHES WAS SET AT PITTSBURGH PA TODAY.   
THIS BREAKS THE OLD RECORD OF 2.1 SET IN 1935.

A RECORD SNOWFALL OF 4.8 INCHES WAS SET AT BRIDGEPORT CT YESTERDAY.   
THIS BREAKS THE OLD RECORD OF 3.1 SET IN 1959.  

A RECORD SNOWFALL OF 0.9 INCHES WAS SET AT WASHINGTON DULLES DC YESTERDAY.   
THIS BREAKS THE OLD RECORD OF 0.3 SET IN 1993.  
  

Highest Snow Reports:

Connecticut:

East Hamton: 12″
North Stonington: 12″
Clinton: 12″

Massachusettes:

Worcester County: 13.2″
Providence County: 13″

So its been an interesting and busy month across the U.S. While the temp departure from normal isnt impressive in fact warm, here’s a look back at the snow events across the lower 48 excluding out west or small lake effect snows for time saving purposes.

December 9th-11th – Upper MidWest Snows, snows to northern Texas. Snows to Maine

December 16-17-18 – Maine and Eastern NH up to a foot of snow in spots and 30 inches for mountains.

December 20-21 – Sub 990mb Low Major Winter storm with over a foot of snow in Wisconsin, Iowa and Michigan. Blizzard conditions.  Over half foot in NV, UT, AZ, NM, CO, KS, NE, IA, IL, WI, MI.

December 24th – Southern Slider clips PA, Central and Northern NJ, southern NY, CT and RI with snow. Light coating. Small System

December 27th – Another system sliding south of Long Island. Generally a light 2-4″ spread out event across NYC metro, PA and CT

December 29th – Sub 980mb low off Nantucket. 8-12″ from Central CT shoreline and areas in the entire half of Eastern CT. 2-6″ from PA, NY, NJ, MA, NH. Some areas of VT got another 6-9″ as well. The adirondaks have over a foot at the base and over 2′ at the summits confirmed by calling the adk lodge.

 

Radar Loop Friday 7pm Dec.28 to Saturday 6pm Dec. 29

 

Radar Loop Friday 7pm Dec 28 to Saturday 6pm Dec. 29, 2012

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