Storm Recap And Tuesday Night/Wednesday Snow Threat

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RECAP OF TODAY: The storm today turned out to have a few surprises after all. In one of the largest failures of short-range HRRR/RAP guidance, banding was not properly forecast across much of Fairfield County, where actually some of the highest snowfall accumulations were seen which came as a surprise.  Snow also continued slightly longer than expected, with one moderate band even continuing into the evening as seen here.  The result was a very impressive snowfall gradient across the county, where anywhere from 2 to 5 inches of snow was observed just in that one county.  This was the exact range instead forecast for New Haven County, where this banding was shown being set up by the majority of mesoscale guidance.  The below snowfall accumulations are the latest as of 7:30 PM:

...FAIRFIELD COUNTY...
   3 NNE NEW FAIRFIELD    5.0   600 PM  2/08  TRAINED SPOTTER
   3 SSE BROOKFIELD       4.0   500 PM  2/08  TRAINED SPOTTER
   WESTPORT               4.0   600 PM  2/08  PUBLIC
   DANBURY                4.0   300 PM  2/08  SOCIAL MEDIA
   NEW CANAAN             3.8   500 PM  2/08  CT DOT
   BRIDGEPORT AIRPORT     3.5   700 PM  2/08  COOP
   FAIRFIELD              3.0   509 PM  2/08  PUBLIC
   WILTON                 3.0   500 PM  2/08  PUBLIC
   GREENWICH              3.0   215 PM  2/08  PUBLIC
   DARIEN                 2.0   300 PM  2/08  CT DOT

We see that New Fairfield and Brookfield actually topped off the Fairfield County accumulations, though there was a report of 6 inches at New Milford that we saw on social media.  The official Bridgeport accumulation was only 3.5 inches, which seems a little low compared to radar estimates but still was above our final 1-3 inch forecast; I should have stick with the 2-4 inch forecast I had most of yesterday before short-range guidance made it seem like that larger band would set up across New Haven County.  Fairfield County is where the forecast went most wrong, as schools ended up dismissing early despite a plethora of guidance indicating that regular closures would be better.  Across Greenwich/Stamford this still would have been the right call, but further north and east the snow continued longer, potentially making the early dismissal the correct call in a very marginal scenario.

What was more puzzling was that New Haven County did not see accumulations that were all that impressive and that there was a wide range of disagreement in these numbers.  The Fairfield County numbers should have instead gone here, as the Fairfield County band sapped the energy from the band that was supposed to form over New Haven County and enhance their snowfall accumulations.

...NEW HAVEN COUNTY...
   SOUTHBURY              2.5   500 PM  2/08  CT DOT
   MILFORD                2.3   500 PM  2/08  CT DOT
   WATERBURY              2.3   500 PM  2/08  CT DOT
   NEW HAVEN              2.0   500 PM  2/08  CT DOT
   BRANFORD               2.0   422 PM  2/08  SOCIAL MEDIA
   BEACON FALLS           1.8   500 PM  2/08  CT DOT
   MERIDEN                1.0   300 PM  2/08  CT DOT
   2 ENE MERIDEN          1.0   536 PM  2/08  TRAINED SPOTTER

The Meriden forecast of only an inch looks very suspect when looking at radar, as do a number of New Haven forecasts.  It was a significant surprise that Southbury saw the highest accumulations in the county, as almost every model was consistent with this region seeing the most snow.  In fact, the National Weather Service upgraded to the region to see 6+ inches of snow in a Winter Storm Warning.  I was not as confident with that and kept them in the 2-5 inch range, which generally looked to have worked out better, but still these lower numbers are a bit of a shock.  I expect the final numbers will still come in a bit higher regardless, but here the storm was really not that bad and some of the school closures may not have been necessary.

Finally, the Westchester County forecast worked out almost perfectly, as seen below.

...WESTCHESTER COUNTY...
   ARMONK                 2.7   145 PM  2/08  PUBLIC
   HARRISON               2.0   413 PM  2/08  SOCIAL MEDIA
   HASTINGS-ON-HUDSON     1.0   330 PM  2/08  PUBLIC

That band in Fairfield County didn’t quite get to this county, and so instead the forecast worked just as models and I had expected.  We generally saw 1-3 inches of snow, and most schools here did not dismiss early, instead opting to cancel after school activities as snow died down by 2 or 3 PM.  It was the enhanced banding over Fairfield County that increased snowfall amounts there and decreased them over New Haven County, but that did not impact the western extent of the snowfall in Westchester County where there were almost no surprises.

After a number of good performances from the HRRR model, this one was a relatively sizable failure, as was also the case with the RAP which was for awhile showing widespread amounts of 4-6 inches across New Haven County.  There was some banding shown across Fairfield County, but it was not shown being that impressive.  Instead, we ended up with some surprise snowfall.

TONIGHT: As was shown on the radar above, a moderate burst of snowfall is moving through the state now, and another half inch to maybe an inch of snowfall can be expected through about midnight tonight.  The HRRR here only shows about half an inch moving through 9 AM tomorrow, with most falling before midnight.  In fact, after midnight it is increasingly looking like we clear out and we could be relatively sunny come tomorrow morning.

TOMORROW NIGHT/WEDNESDAY: Later tomorrow into tomorrow night and Wednesday is when the next chance of snow arrives, and it may be the last substantial one for the week.  A weak low pressure center/Clipper will move to our south, and with it will be an accompanying enhance area of snow.  It will be a very small area of snow, but could pack a punch with snowfall rates up to an inch per hour.  Model guidance varies on exactly where we should expect this to track.   The 18z HD NAM shows that it may hit the region Wednesday morning, per this forecast radar image at 4 AM here.  The SREFs for the same time are much less convinced, as seen here, instead favoring the storm sliding to the south.  The 18z GFS similarly keeps all moderate snow over New Jersey and just gives us flurries overnight Tuesday night here.  And at 6 AM on Wednesday, the NMM shows a glancing blow while the ARW misses us entirely here.  The RGEM is a little more amplified, showing the potential for up to an inch of snow through 7 AM here.  A slight jog to the north on most of this guidance and we see a quick enough burst of snow to cause some impacts.

More on this Tuesday night/Wednesday snow threat will be available in the coming day, as well as a brief update on the weekend severe cold which could bring wind chills down below 0 across virtually all of the SWCT/NY region Saturday night.

 

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