Friday, June 10, 2016

Challenging Saturday Forecast

A warm front will lift through Southern New England on Saturday followed by a cold front Saturday night.  At the same time a complex of thunderstorms currently in the Great Lakes may survive the trip across NY/PA and enter Southern New England tomorrow afternoon.  High resolution computer guidance suggests this moves across MA/RI/CT but climatology suggests it stays south.  Let's break it down.

Current Conditions
Here is the current surface chart.  The warm front is in red across MI, PA and VA.  The current severe weather complex is associated with the low pressure across MN and WI
WPC Surface Analysis 5 PM
This evening is fine- maybe a bit cool for June 10 but very comfortable.  Meanwhile here is the Great Lakes regional radar
NWS Great Lakes regional radar
This complex of storm will strengthen and sustain itself overnight.   By noon time guidance suggests it is ready to enter Southern New England.
18z NAM hires Simulated Radar 12 PM (image College of Dupage NeXLaB)
The surface analysis an hour later shows the warm front ready to advance through New England
WPC surface analysis 1 PM Saturday
I do believe this complex stays alive- but will it get into Southern New England?  I think so but I cannot say where this tracks until tomorrow.  The timing will be roughly 12-4 PM and the complex will feature heavy rain, gusty winds and lightning.   The Storm Prediction Center has Central/Western MA, RI and CT in a risk of severe thunderstorms
SPC Saturday Severe Thunderstorm Outlook
Next we have to consider the trailing cold front Saturday night.  There is the chance for strong storms as the cold front moves through Saturday night.  It is early in the season for nocturnal New England thunderstorms so I will evaluate this tomorrow.  I apologize that this "forecast" is a lot of "I believe" and "chance" but until 12 hours ago it looked like the weekend would be OK save for Saturday night storms.  Perhaps as a forecaster we have been spoiled by technology and this is one of the times that I have to actually forecast so here goes.

Saturday 12-4 PM - Rain with embedded thunderstorms.

Saturday 4-9 PM - Isolated showers/thunderstorms.  Thunderstorms more likely in CT/RI.

Saturday 9 PM - Sunday 5 AM - 50% chance of thunderstorms- will have to refine this later.  Please be aware of the possibility.

-Zack Green

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