Thursday, March 21, 2013

No Warmth in Site, but Sunny Weekend

An interaction in the atmosphere will lead to the formation of a snow band this afternoon and evening.  The amounts will be light but inside of 495 can expect 2-4 inches.  Southern Worcester County, RI, and Eastern CT can also expect a dusting to an inch.  After this I do not see any snow threats (fingers crossed) but I also see no spring like temperatures.  I guess I'll take it, since there is nothing I can do about it!

Current Observations/Long Range Discussion
What is the primary cause of the below normal temperatures?  The easiest way to show this is through the Jet Stream which (for lack of a better way) separates the cold from the warm.  Last winter it pretty much stayed in Canada (positive AO, NAO).  Here it is this morning
06z NAM initialized 250 wind 
I've drawn in the general flow in red.  Here are the current national temperatures.
National Temperature Analysis 5 am (image weatherbell)
Here is March to date in the US
NCEP temp anomaly March (image weatherbell)
Here is the end of March forecast
CPC 8-14 day forecast
How does precipitation look? Well over the next 7 days I expect only light precipitation in Southern New England (all of New England for that matter).
WPC 7 day precipitation forecast
I like to see the precipitation in the Plains, but I do wish Texas would get more rain.  These cold PDO/warm AMO are bad for the Lone Star State.  Here is the drought outlook
US drought Monitor 
I'm showing this because it impacts our lives in New England.  This is where most of our food is grown; drought sends prices up.  

Short Term Forecast
Low pressure will pass offshore today, but will interact with an upper atmosphere feature and drop potentially significant snowfall in SE MA today.  Here is the surface
WPC surface analysis 330 am EST
Here is what the upper levels looks like tonight at 8 PM, off the 06z NAM regular
06z NAM 500 mb vorticity 
How much snow? Here lies my issue.  The NAM is very bullish and is more apt to handle a small scale feature like this.  The EURO isn't as bullish but is trending that way.  I actually trust the NAM hires at this moment over other guidance.  So without further ado 

SNE snow forecast tonight
Temperatures today are in the upper 30's.  Tomorrow, Saturday, and Sunday will moderate slightly so temps may hit 40 by the weekend.  Fingers crossed, this looks like the only precipitation for the next 5-7 days.  Have a good day.











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