Sunday, February 24, 2013

Short Range Forecast, Long Range Discussion

Looking back on this storm I made several mistakes.  First of all I am jumping on the long range a bit too quickly.  To be fair there was considerable agreement 3-4 days out, then it backed away as it became apparent the main storm would be weaker.  I also knew Central New England was going to get pounded but compromised with 6-10.  Many locations are already exceeding that with additional snow to come.
NWS Gray radar return 1254 PM
Here in Southern New England rain is changing to snow
NWS Boston radar return 1257 PM
The bright colors in SE MA is a good approximation as to where the rain/snow line is.  Here is the surface analysis 
HPC 10 am Surface Analysis
Notice the primary low south of the Cape.  That system was largely responsible for the snow/rain yesterday.  Today we seeing an interaction between an Upper level system with a weak surface low (remnants of the Plains snowstorm earlier in the week) and the coastal storm.  
NOAA GOES_E Water Vapor 1245 PM
Cyclonic (counter clockwise) flow around both is leading to a convergence zone in Maine/NH as well as SE MA.  Temperatures are crashing, so most places will go to all snow for the rest of the day.  Winds have shifted in Eastern MA
12 Noon 2 m Temps (image weatherbell)
Notice winds are off the land, not water.  North wind is the snow wind
10 m winds
As I type snow is building back west of Worcester.  The latest RAP model (very short range) is has this for additional snow accumulations 
17z RAP total snowfall through 1 am (image weatherbell)
So all in all we didn't get the coastal storm that was originally anticipated, but we will end up with a small-moderate event.

Monday
Storm clears overnight and Monday will be nice. High pressure takes control and most of the region is in the mid to upper 30's.  CT looks to approach 40.
NAM Hires 2 m T 1 PM Monday (image weatherbell)
Tuesday
Another nice day under the influence of high pressure.  Similar to Monday in all regards.

Wednesday-Saturday
Ah yes.  Here is what I am seeing- a strong winter storm will impact the Southern Plains beginning today (Sunday).  It will track to the NE towards the Great Lakes.  It will run into a block, slow its momentum and develop a new low pressure center off the Mid Atlantic coast by Wednesday morning.  A powerful high pressure area will begin to develop in Canada- looking at possibly a 1050 high!  This is very complex; in fact I don't have many details for you as of this morning.  The models will struggle and so will forecasters.   My take is that the EURO will have the best forecast so I will likely lean heavily on that model and its output.

So that puts snow down Wednesday Morning before a switch to rain, then back to snow.  My best advice is  look out for snow/rain/wind  for the second half of the week.  Plenty of time to fine tune the details but my sense is something big is lurking.  I won't post until tomorrow afternoon as I have a post to do for Tornado Titans.  Look for the weekly snowfall outlook on that site! 











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