Archive for November, 2012

November 2012 in review
November 30, 2012

By Meteorologist Mike Skurko

This November was colder than normal, giving us our first “below average” month this year.  Our average high temperature at Bradley International was 49.1 degrees, which is 2.5 degrees below normal.  Our average overnight low was 30.8 degrees, which is also 2.4 degrees below normal.  Even more impressively, this was the first month since February 2011 that our monthly low temperature was below normal!

We only had 0.4 inches of precipitation this November, which would classify it as a very dry month.  However, that little bit of liquid water translated into 2.9 inches of snow this month.  That puts us much closer to normal … as the average amount of seasonal snowfall by November 30th is 2.0 inches.

“Active” 2012 hurricane season ends
November 29, 2012

By Meteorologist Mike Skurko

November 30 marks the end of the Atlantic hurricane season … the four-month period from June to November that is traditionally the most active in the tropics.  With the effects of Hurricane Sandy becoming the biggest headline in 2012, the hurricane season as a whole was more active than usual.

19 storms were named, 10 of which became hurricanes, and one achieving major hurricane status (Category 3 Hurricane Michael).  The average numbers for a hurricane season are 12 named storms, 6 hurricanes, and 3 major hurricanes.

This is the seventh consecutive year that no major hurricane (category 3 or higher) made landfall in the United States.  Hurricane Sandy was only a Category 1 hurricane when it made landfall in the Northeast.

Other notable records for Hurricane Sandy:

– At it’s strongest point, Sandy’s barometric pressure dropped to 940 mb, the lowest all-time for a storm north of the Carolinas.

– Sandy made landfall with a central pressure of 946 mb, the second strongest landfall all-time for a storm north of the Carolinas.  The most intense storm at landfall was the Great New England Hurricane of 1938, which had a central pressure of 941 mb at landfall.

– The area of gale force winds associated with Sandy reached a diameter of 945 miles, the largest such diameter recorded for a storm in the Atlantic basin.

– Damage estimates of more than $65 billion will make it the second-costliest Atlantic hurricane behind Katrina ($108B)

NOAA also classified the 2012 season as above-normal based on the overall number, strength, and duration of all tropical systems, and ranked it as the 11th busiest over the last 30 years.

Predictions at the beginning of the hurricane season called for a less-active hurricane season, based on global climate model forecasts for an El Nino this summer, which traditionally limits tropical activity.  El Nino never reached it’s anticipated strength, likely allowing for more storms to develop.  NOAA also notes that, with the exception of Hurricane Sandy, a persistent jet stream over the eastern U.S. helped keep most storms well out at sea and virtually unnoticed by the public.

Tuesday’s snowfall reports
November 28, 2012

By Meteorologist Mike Skurko

Western Massachusetts dealt with less than an inch of snow on Tuesday, with a couple of inches more staying off to our south.  Here is a map from the National Weather Service showcasing Tuesday’s snowfall reports across southern New England.

Tuesday’s snow accumulations dwindling
November 25, 2012

By Meteorologist Mike Skurko

A few days ago, the potential for a minor snowstorm was making weather headlines for western Massachusetts.  While previous forecasts have gone with a possibility of 3 inches of snow even in the Springfield area, that chance is looking less and less likely with the latest model runs.

Below are two computer models for mid-day Tuesday.  A trough digging into the northeast will provide the instability to generate some snow showers (it certainly will be cold enough here) for some light-to-moderate snow.  However, the track of this system keeps nudging the core of precipitation south.  The first model (NAM) shows us our best possibility of precipitation (shaded in green) stretching northward into western Massachusetts.  However, the last 24 hours have had more of a variety of computer models showing signs like the bottom picture (GFS) … where precipitation gives us a complete miss.

Finally, this computer image courtesy of the Penn State Meteorology Department shows the probability of at least one inch of snow, averaged out from all computer models … and you can see this map only places that chance at about 30-40 percent.  Therefore, tonight’s forecast is going to back off a little bit on the snowfall totals.  We’re starting to look lucky if Springfield sees just one inch.  It also appears that the timing of this system may be nudged forward a little bit … looking more like a mid-day Tuesday arrival rather than a Tuesday evening.

No matter what the scenario/accumulations, one thing still remains certain … snow accumulations will generally be more for areas south of the Mass Pike and taper off as you go further north.

Nor’easter brewing for mid-week (Sunday update)
November 4, 2012

By Meteorologist Mike Skurko

Some updates to the potential storm system for mid-week.  It still is looking like a mainly rain event for the Springfield area.  Below is this afternoon’s GFS model forecast for 10 a.m. Wednesday morning.  This is the same computer model, same time that was discussed in the Weather Blog entry yesterday.  This is just today’s updated simulation.

The parameters are virtually the same here…a 992-mb low pressure center that will move northward into the region for Wednesday and Thursday.  The 540-line (the southern-most blue dashed line, discussed yesterday) stay relatively in the same position, perhaps even shifts ever-so-slightly northward for this storm, which would continue to support a mainly rain forecast similar to yesterday’s computer model.  The only minor adjustment to be made would be the timing, as this low appears to be slowing down a little bit, which would bring precipitation into western Massachusetts starting Wednesday afternoon, not right at sunrise.

However, a new model is now picking up on this storm.  The NAM, which is the primary short-range model we use, issues forecasts for the next 84 hours out.  That takes us through Wednesday morning, so we can now see how it is handling this storm.  As you can see below, it has a different idea regarding this system.  The following image is also for 10 a.m. Wednesday morning:

It swings the low further east and out to sea…which would be good and bad for western Massachusetts.  The good – it would pull the heavier precipitation and stronger winds away from us.  The bad – this would introduce a better probability for it to be cold enough for more snow.  Notice how the 540-line hugs the coastline much more closely, cutting right through western Massachusetts.  This is typical for these types of low-pressure systems…the further it swings out to sea, the more cold air that can collapse down into western Massachusetts from Canada on the western side of the storm.

This does seem like an outlier scenario however.  The ensemble forecasts…which generally means an “average” of all the models…still greatly favor rain.  The ensemble model below (image courtesy Penn State Meteorology), which shows the probability of a rain event, still puts the Springfield area and much of the Pioneer Valley at a 75-85% chance of rain late Wednesday night (1 a.m.).  Meanwhile, the Berkshires drop off to more of a 50-50 split for the chance of rain at that time.

Nor’easter brewing for mid-week
November 3, 2012

By Meteorologist Mike Skurko

Rumors about a nor’easter ready to hit the Mid-Atlantic and New England coastlines again this upcoming week are correct.  Much like Sandy, this system will ride up the Atlantic coast, strengthen, and then deliver another unwanted round of rain and wind.  It is important to note that this will not be a repeat of Sandy, but conditions will be very dreary for Wednesday and Thursday.

Below is a raw computer model for 10 a.m. Wednesday morning.  A well-defined low pressure center continues to deepen to a surface pressure of about 990 millibars (Sandy dropped down to a record 940 millibars at its strongest point).  This is a decent, but not earth-shattering low pressure system.

The green, blue, and purple colors surrounding  the low represent precipitation.  Fortunately, this will mostly be in the form of a chilly rain.  However, you’ve also probably heard the rumors of potential snow with this system.  Those are true as well, but more likely for the higher elevations.  In western Massachusetts, the possibility exists for a couple inches of wet snow towards the Berkshires.  In the Springfield area, this will still stay mostly as rain, but there could be some non-accumulating snowflakes mixed in as temperatures generally stay in the upper-30s to mid-40s.

Temperatures are represented by the red and blue dashed lines running through the map.  These are atmospheric thicknesses…the warmer a column of air is, the higher the thickness number will be.  A thickness of 540 represents the 50/50 line, meaning it generally rains half the time and snows half the time that the thickness is at 540.  On these maps, the 540 line is the most southern blue-dashed line.

Below is the same computer model for 1 p.m. Thursday afternoon.  Notice how the 540 line gets close to western Massachusetts, but we still manage to stay just warm enough for the second day of this system.

Therefore, forecasts are still calling for a nor’easter to impact New England mid-week, but it will mostly be a wind-driven, cold rain.  As for wind speeds, this particular computer model (GFS) is printing out wind speeds in Springfield of about 25 mph early Wednesday evening when this low reaches its strongest point just before landfall.

So…snow is likely to mix into the Berkshires (perhaps a Winter Weather Advisory-caliber snow, but it still looks a little too warm to see any significant snow impacts for the rest of the Pioneer Valley at this point.  It will be a windy, raw two days for us.  Stay tuned!