Monthly Archives: January 2012

Photo of Libby / Courtesy: Jeremy Keckler

An impressive mesoscale banding featured developed in southern Connecticut that sat and sat and sat over the same area. These things can produce some exceptional totals in a relatively short total and this was no exception. This produced the big totals thanks to a growing and relatively stagnant area of low/mid level frontogenesis that worked in tandem with synoptic scale lift from the right entrance region of a jet streak in central New England.

Here are the totals from my awesome weather watchers:

• East Haddam – 10.5″
• Salem – 10.5″
• North Guilford – 10.0″
• Woodbridge – 10.0″
• Montville – 10.0″
• Haddam – 9.8″
• Newtown 9.5″
• Higganum – 9.0″
• Branford – 8.3″
• Ansonia – 8.2″
• Wallingford – 8.0″
• Old Saybrook – 8.0″
• New Haven – 8.0″
• East Hampton – 8.0″
• Franklin – 7.0″
• Ledyard – 7.0″
• Naugatuck – 7.0″
• Oxford – 7.0″
• Groton – 6.5″
• Colchester – 6.5″
• Wolcott – 6.5″
• Bridgeport (BDR/Official) – 6.2″
• Southington – 5.5″
• Vernon – 5.0″
• Tolland – 3.9″
• West Hartford – 3.8″
• Litchfield – 3.0″
• Avon – 2.8″
• Stafford Springs – 2.6″
• Windsor Locks – 2.4″
• East Granby – 2.0″

Thanks for the reports! Enjoy the snow

If you don’t want to geek out and read all this… the bottom line is I expect most of us to 4″-6″ of snow in Connecticut and most of southern New England.

Finally some real snow in the forecast! Here’s the 12z NAM valid at 15z (10 a.m.) Saturday with 850mb temperatures (0c solid black) and 3-hour QPF shaded. As usual the NAM is the most robust of all our models in terms of precipitation.

A weak disturbance is ejecting east toward southern New England. Though the shortwave isn’t strong we’ll get a burst of QG forcing (lift) thanks to warm advection and a 60+ m/s jet streak to our north leaving us in the favorable right entrance region.

NAM dynamic tropopause forecast for 15z Saturday. Isotachs shown - note the 60m/s jet streak northeast of Connecticut on the DT.

12z NAM forecast of sea level pressure and 1000-500mb thickness valid 18z Saturday

In the NAM SLP/Thickness map you can see the relatively tight thickness gradient over NY and New England which will help maximize low level warm advection even with a relatively weak low level jet. In addition synoptic scale lift will be present through the column in right entrance region of jet streak to the north.

The bottom line is that snow will overspread the state shortly before daybreak Saturday with 4″-6″ of snow likely across all of Connecticut. I expect snow even down to the shoreline (including the Groton/Stonington snow hole). Snow to liquid ratios will be better than 10:1 with relatively cold soundings and some lift and saturation into the favorable dendritic growth zone. This isn’t a classic setup for good snow growth so I expect 15:1 snow:liquid ratios.

On a side note I couldn’t help but notice this National Weather Service map this morning. I generally don’t look at their forecasts or discussions but this really jumped out at me.

How the hell is this supposed to make any sense to anyone? A winter storm watch for Fairfield County and a winter weather advisory for the remainder of southern Connecticut. Nothing to the north? Why? Will Bridgeport get more snow than New Haven?  Snow should begin around the same time so why do we have watches, advisories, and nothing in effect when the storm appears ready to deliver similar impacts regionwide.

To be honest I don’t even know what the criteria is for each advisory or warning for each county because the definitions seems to change every couple years and they vary from county-to-county and state-to-state.

The NWS does a great job (most of the time) with severe thunderstorm and tornado warnings but maps like this do everyone a disservice. It makes no sense.

It’s taken long enough but this evening we have two weather events on our radar. Ironically, the pattern is still a mild one, with well above normal temperatures on the way for much of next week.

Still, well timed (or poorly timed, based on your perspective) disturbances will produce snow across Connecticut tonight and again on Saturday.

Tonight’s system is moisture starved and not terribly dynamic so I wouldn’t expect much. That said, 1″-2″ of snow is possible in some areas with a moist onshore flow keeping southern New England a bit more primed for snow than inland areas to our north and west. A touch of frontogenesis appears to be enough along with QG forcing/ascent to produce some locally heavy bands of snow this evening.

As for Saturday, most years this storm wouldn’t be much of a story, this year it is. A slightly more juicy and dynamic shortwave is ejecting from the Pacific northwest (the one that produced the snowstorm and ice storm near Seattle) will produce some strong lift and a more widespread batch of snow. A bit of mid level warmth gets introduced which may mean some sleet or freezing rain particularly for areas south of Hartford. Details to be determined but at this point I feel pretty good about 2″-4″ of snow on Saturday with the potential for 6″ somewhere though most of us will see less.

Here’s the 15z SREF snow probabilities which aren’t overly impressive though they should bump up in coming runs.

Don’t fret if you don’t like snow. It looks like the torch returns by Monday with a warm pattern setting up. Here’s the 12z GFS MOS for next week:

In the grand scheme of things this winter still is a bit of a downer but I do see some signs of larger storm threats beyond day 10. -NAO????? Stay tuned….