Potentially Wild Week of Weather

March can be fun for meteorologists in Connecticut. There are two main things that I’m watching – the potential for gusty winds, small hail and thunderstorms on Thursday and a nearby nor’easter Sunday night and Monday.

Let’s start with the nor’easter. There is a fair amount of spread in current model solutions ranging from a major snowstorm to a whiff to the east (GFS). In between is the European model solution.

gfs_op_apcp_f132_ne

ecmwf_apcp_f144_ne (1)

While the GFS and to a lesser extent the Euro are tame solutions there are signs that we need to watch this very closely. First of all, the Euro Ensemble mean is tucked inside and west of the operational Euro. This tends to be a big caution flag.

mthk_f144_bg_US

While there are some out to sea solutions among the 51 ensemble members there is a rather notable clustering (in fact the tightest clustering) over the “benchmark” of 40N/70W which is significant. Does this make sense? It’s actually a decent pattern for a snowstorm with downstream ridging over Greenland and some semblance of a 50/50 low – that upper level low near Newfoundland.

500vty_f120_bg_NA

So…. we watch. Cold air and a favorable pattern for a storm are big signs to watch this closely. I think it’s fair to say there’s about a 50/50 shot at a decent nor’easter in Connecticut. Whether it’s rain, snow or both it’s just too early to say – but if the storm track is right this could be a significant winter storm in southern New England.

Now, backing up to Thursday. A pool of very cold temperatures in the mid levels of the atmosphere will lead to an impressive unstable airmass overhead. In fact, 500mb temperatures of -33C will lead to exceptionally steep lapse rates. What do I mean by that? There’s going to be an unusually large difference between temperatures between the ground and temperatures 20,000 feet up.

gfsNE_500_temp_048

What does this mean for sensible weather? Gusty winds – possibly up to 50 mph are a decent bet. In addition, IF we can muster up adequate moisture thunderstorms could produce small hail and damaging wind gusts. This is a possibility. Soundings from both the NAM and GFS show classic inverted-V profiles which is a classic sign for strong winds if thunderstorms can develop.

gfs nam

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