Last Minute Critical Storm Trends - March 5th Snowstorm

A stretched out frontal system from the east coast all the way to Texas is set to move into our area around Midnight and bring moderate to heavy snow accumulations. Once the mid-level trough containing the H5 s/w energy tracks to the Great Lakes Thursday morning, it will help strengthen dynamics in the mid to upper atmosphere to produce impressive snow rates generated by frontogenesis. The upward motion in our atmosphere is what will help spread precipitation as far north as southern New England. 

Check out these latest developments:

6z GFS H5 vorticity map valid 1pm Thursday

18z GFS H5 vorticity map valid 1pm Thursday

The difference between these 2 images is quite remarkable considering the event will begin around Midnight. In the morning GFS run, H5 trough over the Ohio Valley is faster (progressive), shows strung out energy, which results in lower heights over the east coast. 

On the afternoon run of the GFS, the mid-level trough is slower, steeper, more consolidated which allows heights to rise along the east coast. This is huge because any waves of energy that develop along the draped front along the east coast will ride further north into NYC Metro and southern New England instead of tracking to the south. 

What happens as a result with the upper level jet streak?

6z GFS valid 4pm Thursday:

18z GFS valid 4pm Thursday:

Wow! The 6z GFS basically weakened the jet streak and had it placed over the area, while the 18z GFS is much more impressive with it and has it positioned much more favorably to our N&W so the best dynamics get into our area. 

Speaking of dynamics...

What happens as a result with the H7 frontogenic forcing?

6z GFS valid 7am Thursday:

18z GFS valid 7am Thursday:

There is now lift getting into EPA, NNJ, NYC, southern NY, and CT. 

What does all this mean? 

A new snow map will be released at 10pm to account for these last minute changes in the atmosphere. I noticed with the 12z runs there were subtle changes but I did not expect that to continue into the evening runs. The GFS also has support from the reliable RGEM, as well as, the SREFS, CMC & EURO models. Areas in NEPA, NNJ, southern NY into CT can expect higher snow amounts as a result. 

Stay tuned on the forums for the latest!! 

-Francesco Paparatto

P.S. latest HRRR has rain changing to snow from west to east between Midnight and 2am. By 7am, heavy snow is falling over the area.

Links:

www.njstrongweatherforum.com

www.usa-wx.com