Meh "Winter Weather" Event Saturday, March 9th, 2019 into Sunday, March 10th, 2019

After quite a pleasant Saturday with ample sunshine and temperatures soaring into the 40's (an indication that spring isn't far away :D) we do have a bit of winter weather to deal with moving into Sunday morning, however, this will not be a big deal as temperatures will quickly go above freezing.

A rather potent low pressure system moving northeast into the upper-Midwest producing significant snow across the upper-Midwest and severe weather across parts of the south will push a warm front towards our area. High pressure to our north will try to lock in some colder air in the lower-levels of the atmosphere which is why we'll start out as some wintry precipitation:

Forecast models do show some decent lift moving into the area towards Sunday morning with 15 units of omega within the snow growth zone. Unfortunately, the temperature profile looks more supportive of sleet with a marginal thermal profile with temperatures several thousand feet up not much above-freezing. Surface temperatures tonight will also struggle to get below-freezing across many spots.

Coldest temperatures will be confined to the extreme northern part of the state and some of these areas may yield a coating of sleet before everything transitions over to rain through Sunday morning. All in all...no big deal.

Don't forget to set those clocks ahead before bed tonight!

Updated CT snowfall Forecast: Sunday, March 3rd, 2019

It has been an extremely rough (downright embarrassing) past 48-hours in terms of my snowfall forecasts. I've taken some time to really explore what I had done wrong and the good news is (with help from some fellow meteorologists) I have figured out what I did (perhaps I will throw together a separate post for this).

Anyways...computer forecast models continue to become rather impressive for tonight into Monday morning suggesting some very heavy snowfall in a short-period of time. Snowfall rates of 2-3'' per hour are becoming increasingly likely.

The Hi-Resolution Rapid Refresh (HRRR) forecast model continues to really ramp up the snow totals for tonight and this is due to some very strong upward vertical motion penetrating the snow growth zone. Below is a snap shot of the HRRR for Windsor Locks, CT showing 30 units of omega within the snow growth zone (the purple and yellow contours). This is indicative of very intense upward vertical motion and with sufficient moisture this will yield extremely heavy snow (potentially 2-3'' per hour. As a note, other forecast guidance is along the same lines of thinking:

The latest run of the NAM forecast model shows very intense 700mb frontogenesis traversing CT with very intense 850mb frontogenesis just south of the state. Frontogenesis is a term which defines rapid changes in the horizontal temperature gradient over time. The greater the gradient, the more intense the upward vertical motion and the heavier the precipitation (so long sufficient moisture is present):

Forecast sounding from a location in CT shows incredibly lift with a sounding indicative of heavy snowfall:

Based on the latest trends within the forecast models, current radar, and mesoanalysis data it's time to take em up. There may even be some localized amounts up to 14'' if the trends continue.

Heaviest snow falls in the 11:00 PM to 5:00 AM window.

Sunday, March 3, 2019 CT Snow

Unfortunately I was not able to write a blog for the snow event of Friday, March 1, 2019, however, my forecast totally busted...it was way off. My forecast was just way too high. After looking back at everything I realized I should have not gone that high. There were numerous red flags for totals to reach those heights and I overlooked them. With that said...I will not let the same thing happen this time, even though the potential does exist for higher totals. Why won't I be aggressive this time?

The 500mb pattern is awful looking. This level (about 18,000 feet off the ground) is what sort of drives the weather...this is where the main jet stream is located, this is where energy moves through the atmosphere and it is this energy which helps create weather systems. When we look at 500mb vorticity and winds the flow is pretty flat and fast and there are numerous pieces of vorticity instead of a nice consolidated piece and we have a rather elongated piece of vorticity to our northwest:

There are no closed lows at 700mb (about 10,000 feet off the ground) and while we do see a closed low at 850mb this will help generate a band of heavy snow and the question is how far north this gets. You can tell the closed off look by that really tiny circle within the black circled area on the graphic on the right:

The Friday night system, tracking as far south and east as it did also likely set up a baroclinic zone in which this system would most likely follow along.

Water vapor imagery shows our system is currently over the CO area. Going back to the initial image of the 500mb jet stream and vorticity, with the flow nearly zonal (west-to-east(ish) it's tough to see this really gaining latitude. This will likely indicate a track far enough south and east to keep heavy banding to extreme SE CT (and perhaps even farther south and east than this):

What to expect:

• Snow breaks out 5:00 - 8:00 PM west to east across the state.
• Heaviest happens during the overnight.
• May see some initial mixing across SE CT, however, any mixing will transition to all snow.
• Snow is out by 8:00 AM Monday morning.
• Delays likely for the Monday morning commute (especially SE CT)