Post Storm Wrap

Snowfall Reports Courtesy NWS Taunton

Snowfall Reports Courtesy NWS Taunton

Overall, the forecast worked out fairly well for most of the region this time around. If you go to the NWS page that hosts the snowfall map to the left, you’ll find it is interactive. You can pan and zoom into different places and see more reports.

We had banding set up across extreme southeastern NY, southern CT, RI and southeastern MA for a while with this, and that resulted in a few amounts above the forecast range. This type of banding usually occurs in these storms, but it is difficult/impossible to locate where the band will set up in advance. Notice the significant difference in snow amounts between areas north of I-84 (and I-90 east of Sturbridge, MA) and south of these highways.

There is no way to forecast to the inch exactly how much snow will fall in each town ahead of time during these storms. The best we can do is to be right for more places than we are wrong. Heck, I am still amazed that it is even possible to know in advance that it is going to snow. Until very recent history people never knew when snow, tornadoes, hurricanes, etc were about to descend on them and millions died as a result. The fact that many people now expect us to be able to forecast snow amounts to the exact inch, town by town, ahead of time, shows me just how much advancement has taken place in this field in the past few decades. That advancement is directly related to the increasing computer processing speeds and development of sophisticated programs/models that run on these supercomputers. It’s much more populist to say that you can forecast the weather looking out the window, using signs of nature and/or folklore, but that simply can’t compare to the tools that are now available to us. (When’s the last time a woolly bear caterpillar gave you a snowfall range for the I-95 corridor 3 days out)?

Thanks for your comments during this past storm (even the snarky ones). Everything is helpful in fine tuning for the next storm. Now let’s think of some ways to stay warm during the rest of the week!

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Snowfall Forecast Update

Snowfall Forecast Through Wednesday

Snowfall Forecast Through Wednesday

Based on the latest model trends, I am decreasing (slightly) forecast snow amounts.  This change generally amounts to a half-inch to 2.0″ decrease for a number of cities (not all).  I have posted some specific city snow forecasts on my FB page. The rest of the forecast stays as is.

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The Snow’s a Go and the Cold’s Getting Old!

HRRR Snowfall Through 7 PM

HRRR Snowfall Through 7 PM

The models have come into pretty good agreement (including the RPM getting on board since early yesterday) on what we can expect from our latest bout with snow & cold.  Parts of southeastern NY/Long Island, CT, and RI may see some flurries or a little light snow prior to noon, however things mostly get underway during the afternoon hours.  By 7 PM tonight (see image to the left) snow amounts will range from as much as 3″-4″ in NY City and parts of western Long Island to 1″-3″ through much of CT and parts of RI, to less than an inch across parts of western MA.

A feature above the ground known as a “short wave” (see #1 on upper-left panel of image below) will aid the formation of an offshore low pressure area.  Although this low will be a little far away from our area compared to where big snowstorms usually track, one thing it

NAM Forecast 7 PM EST

NAM Forecast 7 PM EST

has going for it are snow to liquid ratios.  Typically around here the amount of snow we get is roughly 10 times the amount of liquid that falls (i.e. 1.0″ liquid=10.0″ snow).  In this case, the conditions in the atmosphere will likely produce ratios that are as high as 15-20 to 1 at times.  At other times during the event, the ratio will be lower than that and it may also be a bit above 20 to 1 for short periods in some locations.  The bottom line is that because of the “fluff factor”, we will get more snow from this that we otherwise would.   I expect to see total accumulations by Wednesday morning of 6″-10″ in areas south & east of a line drawn from the northern tip of NJ, northeast through Brookfield and Hartford, CT, up into northeastern MA.  Amounts will generally decrease as you move further north & west (further away from the storm track), until you get down to less than an inch north & west of Albany, NY.  I have posted an accumulation map and specific city forecast amounts at www.facebook.com/bobcoxweather

This means for most of us both this evening’s and Wednesday morning’s commute will be affected.  The other factor here is the arctic air that’s in play.  Temperatures tonight will be dropping into the single numbers & teens WITH WIND.  North winds will pick up to 15-25 mph, with gusts over 30 mph (especially near the coast).  This will push the Wind Chill Index into the 0 to -15 degree range tonight, along with blowing & drifting snow.  I don’t expect most of the region to see blizzard conditions during this, however there is a Blizzard Warning up for Cape Cod & the Islands, where the wind will be strongest tonight into Wednesday.  Highs will only be in the teens-low 20′s Wednesday, and it will still be windy.  Temperatures will stay cold for the remainder of the week. Lows will be in the single numbers above and below zero Wednesday night/Thursday morning.  The “mildest” day will be Saturday, with temps close to average highs in the 30′s (some 20′s Berkshires & central New England), but there will be snow showers and a gusty wind that day so don’t break out the Bermuda shorts just yet!

 

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What You Might Not Know About Tomorrow….

Yet another Arctic cold front will move across the region by late this afternoon/evening. Some places may even see some flurries or snow showers as it passes.  Moderate temperatures this afternoon will nosedive tonight, dropping into the teens (some single numbers in western MA and closer to 20 in NYC).  Highs Tuesday will be mostly in the teens-low 20′s.  An area of low pressure developing on the offshore front will attempt to throw some snow our way Tuesday afternoon into Tuesday night, tapering off Wednesday

NAM Forecasts 0.5" or more liquid from NYC to Boston and points south & east.  Snow to liquid ratios are likely to be 15-20 to 1 with this, but is the liquid forecast overdone here?

NAM Forecasts 0.5″ or more liquid from NYC to Boston and points south & east. Snow to liquid ratios are likely to be 15-20 to 1 with this, but is the liquid forecast overdone here?

morning.  Snow to liquid ratios are likely to be in the 15-20 to 1 range instead of the typical 10 to 1 ratio.  This means it won’t take a lot of precipitation to result in accumulating snow. The storm is going to be kind of far away from us to really hammer us with snow, and the highest amounts are most likely in the locations furthest south & east – closer to where the storm center will be, well offshore.  The latest indications are that snow amounts of 6″-7″ could occur from parts of Long Island and coastal CT, over into southeastern New England. The further northwest you go, the lower the final amounts Wednesday will tend to be.  So, for example, I’m thinking Boston and NY City get 5″-6″, Hartford sees 3.5″, and parts of northwestern CT and western MA get less than 2″.  Albany, NY and parts of southern VT probably see little or nothing (some of these areas might get more with the arctic front today) and Concord, NH might get an inch by Wednesday morning.

Having said that, there is a big caveat (no weatherman jokes here, please)  ;).  It is still possible that this whole thing ends up happening a little further to the south & east as the

RPM Snowfall Forecast Through Wednesday A.M.

RPM Snowfall Forecast Through Wednesday A.M.

RPM model suggests.  If that ends up being the case, everyone gets less snow, and non-coastal locations could end up with very little to nothing.  This is not totally out of the question at this point.  We’ll see if the RPM gives in later today or if the other models get educated.  Realize that as always, expected snow amounts may change between now and tomorrow.  What won’t change, and you can take to the bank is the fact that it’s going to be mighty cold again starting tonight.

Also, the north wind will pick up to about 15-25 mph later tomorrow into tomorrow night.  Temperatures in most places will be dropping through the teens during the snow (assuming it comes).  The wind chill factor will start out in the single numbers during the snow Tuesday afternoon and drop below zero Tuesday night.  Highs in most locations Wednesday will remain in the teens.  Thursday and Friday’s temperatures don’t look a whole lot better – highs in the teens/low 20′s, lows in the single numbers above and below zero.  NY City might be able to stay above 10 degrees Thursday-Friday.

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Not Too Shabby

NAM Forecast 1 PM EST Wednesday

NAM Forecast 1 PM EST Wednesday

Yesterday’s balmy temperatures felt great, despite the rain.  Stepping out early this morning felt awesome.  Sky was clear, temps were above 40 and the breeze hadn’t kicked in yet.  The air smelled great.  Nice & fresh after being cleansed by yesterday’s rain.

Today will be pretty nice by January standards.  A combination of clouds & some sun.  The breeze picks back up, though.  Highs will be in the 40′s, but tend to drop later this afternoon.  Tonight looks mostly clear with lows in the 20′s in CT & western MA/southern NH, 30′s in NYC, Boston & Providence.  Monday will be mostly sunny with highs in the 40′s to about 50 in some places.  There is the chance for some showers late Monday night/early Tuesday as a weak cold front/trough swings in.  It’s possible that there could be some wet snowflakes by early Tuesday – best chance would be well inland.

Some energy being ejected out of the base of a mid-level trough (circled in black on upper-left panel in image above) could try to initiate low pressure development Wednesday.  For now, we will just look for some rain or snow showers, but we’ll keep an eye on it.

Enjoy the moderate/above average temperature while we have them.  Arctic chill will return by next weekend.

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Polar Vortex Mania

GFS 500 millibar forecast 4 PM EST

GFS 500 millibar forecast 4 PM EST

Apparently the existence of the Polar Vortex is breaking news for many today.  The polar vortex is simply an upper-level low containing a cyclonic circulation of very cold air that is usually found in the vicinity of the north pole – thus the name. Actually, there are usually two vortices (centers of circulation).  One is typically found over northern Canada, and the other over Siberia.  There is also one over the Antarctic.

The displacement of the Polar Vortex down into the Great Lakes this week is the reason the weather has been so cold for so many around the county (and why our region is going back into the deep freeze tonight & Tuesday).  It is not that unusual for the Polar Vortex to be displaced in this manner.  It usually happens at least once or twice per Winter (haven’t checked the stats – that’s a rough guess).  It is not happening because of “Global Warming” or  ”Climate Change”, so don’t be fooled.  Extreme weather is the norm.  Every bit as normal as tepid/tranquil weather is.  ”Normal” temperatures are just an average of all the extremes over the years.

If you not a big fan of the Arctic air outbreaks (a very small fan club, indeed), hang in there.  The pattern is going to change later in the week, allowing temperatures to moderate, then rise above “normal again,  and the coming weeks look less extreme.

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A Blizzard With No Snow?

NAM 15Well, we are underway, and so far the forecast looks to be on track.  Occasional light snow, breezy & cold this afternoon with temps in the teens & 20′s.  The snow gets steadier for a while tonight, along with gusty northeast winds, gradually shifting to north, which will blow the dry, powdery snow around and lower visibility.  Wind speeds will increase to 15-25 mph tonight, with some gusts to 30+ mph and maybe 40+ near the coast.  Temperatures will drop into the single numbers and teens tonight with wind-chills dropping to -10 or colder at times.  The snow will taper to flurries by Friday morning and the flurries will be over by afternoon.  I still like 4″-8″ as a snowfall forecast for most of us.  There may be a few isolated 9″ amounts in CT, but I’m thinking most of the state sees less than that.  There’s a somewhat better chance for 9″ or 10″ on parts of Long Island and it still looks like you could be looking at a foot or more across parts of southeastern MA.

Although this won’t be the biggest snowstorm we’ve ever had, the combination of gusty winds and arctic air will make for nasty conditions tonight into Friday.  Wind chill factors will drop to -5 to -20 at times tonight and not improve much Friday.  Visibility will be reduced by blowing and falling snow.  I expect to see a lot of inaccurate measurements reported after the storm due to people having difficulty measuring the drifted snow properly.

The Winter Storm Warnings remain in effect, except on Long Island and Cape Cod where there is a blizzard warning.  A word about that:  Blizzard warnings have nothing to do with the amount of new snow falling.  A blizzard warning can be issued and blizzard conditions can occur even when total new snowfall is zero.  Blizzard conditions are based on wind & visibility only.  Wind sustained or frequently gusting to 35 mph or more and visibility of 1/4 mile or less due to falling or blowing snow for at least 3 consecutive hours equals blizzard conditions.

Friday night/Saturday morning will feature some of the coldest temperatures we’ve seen in some time.  Lows will drop below zero through most of the region, although some coastal areas and the largest cities like New York, Boston, and Providence have the best chance to stay near or above 0.  There will probably be some colder locations in interior southern New England that see -20 by sunrise Saturday.  Double digits below 0 will be fairly common across the northern half of New England and you’ll probably here about some ridiculously cold lows in some of the nook & crannies up there.

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Latest on the Snow & Cold

nanook-of-the-northI’m not going to make any significant changes to the forecast for Thursday & Friday.  Some spotty, light snow or flurries could start reaching the ground anytime tonight, but the chances increase toward & after midnight.  Looks like a coating to an inch or two will be on the ground by the morning commute.  Lows drop into the teens, with some low 20′s on the south coast & Long Island.  There will be light snow & flurries around at times Thursday and we’ll probably pick up another coating-2″ during the day, bring totals up to 1″-4″ by 7 PM.  I’m still not convinced that we will get into prolonged hours of really heavy snow Thursday night, so I am keeping forecast accumulations by the time the snow ends Friday at 4″-8″, with a couple exceptions.  I wouldn’t be surprised to see some 10″ amounts along the east slopes of the Berkshires and portions of southeastern MA could see a foot or more.  Although it will be unusually cold during the storm, I don’t think the snow-to-liquid ratios (which average around 10-to-1 in this part of the country) are going to be as high as you might think.  At times, they will probably only be 10 or 15-to-1.  The bulk of the moisture will not coincide with the best “snow growth region” above and the upward lift in this zone is not super impressive.  So, for now I am staying with the above accumulations.

The National Weather Service has issued a Winter Storm Warning for the entire region for Thursday into Friday morning.  The exception is Long Island, where a Blizzard Warning is in effect.  Blizzard conditions exist when the visibility is lowered to 1/4 mile or less due to falling or blowing snow and the wind is sustained at or frequently gusting to 35 mph or more.  There used to be a temperature requirement to (20 degrees for a blizzard and 10 degrees for a severe blizzard), but these are no longer used.

The combination of blowing and falling snow, gusty winds and cold temperatures and wind chills will make for a tough go of it Thursday night into Friday.  Lows drop into the single numbers & teens Thursday night, with wind chills falling to -10 to -20 into early Friday. Highs Friday will remain in the single numbers & teens for most of us, with subzero wind-chills.

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Snowfall Trending Down

ECMWF Forecast 1 AM EST Friday

ECMWF Forecast 1 AM EST Friday

Computer modeling of our end of the week event has been trending the system further south & east, and it stays somewhat disorganized for a while.  As a result, I think snowfall amounts between late Wednesday and Friday will be mostly in the 4″-8″ range (1″-2″ less than yesterday’s first guess), with the higher elevations more likely to see some 6″-8″ amounts and everyone else more likely to see 4″-6″ type amounts.  These amounts are still subject to change as further atmospheric changes are assimilated and modeled.  Friday will be windy, with Arctic cold.  Snow ends during the day and most places will not get out of the teens, while well inland (i.e. northern hills CT, western MA, southern VT/NH) highs remain in the single numbers in many cases.  Expect subzero wind-chills Friday.

Meanwhile, we can still expected some batches of flurries & light snow late this afternoon and evening, which may bring a dusting or coating to some towns.  Should be over by 8-9 PM in CT/western MA and shortly thereafter in BOS & PVD.

Happy New Year!

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Midnight Temperatures New Year’s

times_square_new_york_new_year_eve

Here’s what you can expect for temperatures when the ball drops tomorrow night.  Many places will have a 10-15 mph breeze, making it feel about 10 degrees colder, though.

 

New York City: 30

Hartford, CT      24

Boston:                25

Providence:        25

Springfield, VT   16

Worcester, MA   18

Pittsfield, MA      17

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