2014-02-13Sfcst

UPDATE 3:
— Winter Storm Warning in Effect from 7 AM Today to 7 AM Tomorrow–
 
Shrewsbury Area Weather for Today, 2/13/2014 (see disclaimer at bottom)…

1800 2/13 fcst 

Total Precip:  ~9.94″ to ~12.01″ Snow, Sleet, Freezing Rain
 
Measured 9.8″ snow at 5 PM, with the start of mixed precip (IP and ZR)
Details:
The forecast is holding…  We are actually 0.47″ ahead of where my super-dooper Excel-based model predicted (below). 
 
I also want to mention that this storm is not over yet.  The back side of the storm will move through overnight and it is likely that we will get another inch or two of snow by morning…
 
I’ll send a final update tomorrow, and I’ll also tell you about the potential snow storm for Saturday…  😉
 
Steve
UPDATE 2:
— Winter Storm Warning in Effect from 7 AM Today to 7 AM Tomorrow–
 
Shrewsbury Area Weather for Today, 2/13/2014 (see disclaimer at bottom)…

0700 2/13 fcst 

Total Precip:  ~9.94″ to ~12.01″ Snow, Sleet, Freezing Rain
Details:
The storm is “on schedule” so to speak…  Flurries started ~5 AM followed by light snow…  We have ~0.3″ of snow at 7 AM…  Dynamics all look unchanged from yesterday evening, so we are on track for another good snow storm.  Banding to the west of this storm means Berkshires into SW NH could see 18″ plus, while south coastal zones (SE CT/RI/SE MA) will see ~2″ to ~4″ of slushy snow…

It looks clear that the middle of this 24-hour storm will be mixed precip, for our area and I am now wondering about possible mixing of some rain…  I have lowered the low-end of the snow totals, but that is a nod towards compression once the snow is on the ground.  The amount of precip that will fall from the sky won’t change very much from what I forecast yesterday, but snow will compress under its own weight and from the weight of the ice pellets and freezing rain.  Below is one of the models showing the transition from snow to mixed precip and back again to snow:
Inline image 1
The evening commute will be difficult, and tomorrow morning’s commute could also be a bit slick.  Plenty of cancellations and closings have been posted for today, including non-emergency state employees for most (but not all) of the state.  You should not venture out today unless necessary.
Continue to monitor weather reports, especially if you have to travel today.  Give yourself plenty of extra time for tomorrow morning’s commute…
I’ll send updates as the storm progresses…

Steve

UPDATE 1:
— Winter Storm Warning in Effect from 7 AM Tomorrow to 7 AM Friday–
 
Shrewsbury Area Weather for Thursday, 2/13/2014 (see disclaimer at bottom)…

1800 2/12 fcst 

Total Precip:  ~11.10″ to ~12.42″ Snow, Sleet, Freezing Rain
 
Details:
This storm is a mid-latitude cyclone (my personal favorite – nice comma-shaped storm as viewed from satellite) whose central Low will be well inside the 40/70 benchmark. In fact, the center of the storm will run over SE MA and allow plenty of warm air to push into the belly of the storm.   Consequently, this is not an easy storm to forecast, let me tell you!

In general, this looks to be a bigger storm than the last, with accumulations of up to ~24″ of snow for isolated spots in the Berkshires, up to ~18″ for the Worcester Hills, and then it gets tricky for our area (of course)…
My models are showing Shrewsbury will see a transition to mixed precip – mostly freezing rain with some sleet – during the middle segment of the storm, with very heavy snow at the start and finish.  In addition to heavy, wet snow, this mixing means we have a potential for ~0.25″ to ~0.33″ of icing, and potential power outages…
The main axis of precip is actually over the Cape, but this will be mostly mixed precip and rain…
Timing:
Snow looks to start ~6:30 AM with steady accumulation starting ~7:30 AM.  We will see significant snowfall rates of ~1″ to 2″ per hour from ~10:30 AM until ~3:00 PM with potential for ~8″ of snow by early afternoon.  At this point in time, my models say mixed precip (snow, freezing rain, ice pellets) and a slight chance for plain old rain until ~midnight.  We then finish with another big slug of snow that looks to impact the Friday AM commute.
This is what my summary model shows:
Inline image 1
The only issue I have with the above is whether we have a complete changeover to rain tomorrow PM.  If so, snow totals will be lower than what I have forecast.  But, travel in these shifting conditions can actually be worse than all snow because of the associated freezing rain and sleet…
Tomorrow’s early morning morning commute will not be directly impacted, but conditions will deteriorate rapidly towards the end of the AM commute, and driving will get worse as the morning progresses.  The evening commute will be difficult at best, and Friday morning’s commute could also be difficult.  Travel is not advised from 9 AM Thursday through 8 AM Friday.  You should anticipate widespread cancellations and closings tomorrow.
Continue to monitor weather reports tonight, especially if you are contemplating travel late tonight or anytime tomorrow (avoid travel unless you have no choice).  Tune your NOAA All Hazards Wx Radio to Channel 7 for the greater Worcester area…  If you have a scanner or a scanner/radio App for your smart phone, tune to 146.970 MHz for NWS SKYWARN reports and communications covering central MA.
I will send an update tomorrow morning…
Steve
— Winter Storm Watch in Effect Thursday AM to Friday AM —
 
Shrewsbury Area Weather for Thursday, 2/13/2014 (see disclaimer at bottom)…

1800 2/11 fcst 

Tomorrow
Dew Point ~9°F, High T ~26°F, Low T ~17°F, Winds NW – SSE @ 4 – 8 MPH
Precip: None

Thursday
Dew Point ~31°F, High T ~35°F, Low T ~20°F, Winds NE – N @ 5 – 18 MPH
Precip: Snow, mixed precip (IP, ZR)

Friday
Dew Point ~28°F, High T ~37°F, Low T ~30°F, Winds NW – SW @ 8 – 15 MPH
Precip: Snow Showers Early

Total Precip:  ~9.16″ to ~10.99″ snow (maybe…)

Details:
OK, another winter storm and it could be as big or bigger than the last one, maybe…

It is too soon to forecast with high confidence because it looks like the storm track will be well inside the 40/70 benchmark. In fact, it looks like the central Low will pass over SE MA (Plymouth area).  This means a storm start of snow, then a definite mix of Snow/IP/ZR and possibly rain, then finishing again as snow for our area.  I am looking at a 540mb line/32°F line running from Hartford CT to Worcester MA to Portsmouth NH (basically I-84/I-90/I-290/I-495/I-93), meaning everything east and south will be mixed precip with increasing amounts of rain approaching the SE coast…
If the High sitting over northern New England stayed put, all precip would be snow and we could be easily looking at ~1 foot of snow (one of my Excel-based models came up with a max of ~16.44″ of snow).  Because the High is moving out into the Gulf of Maine allowing warm air to move into our area, we will have a warmer solution with mixed precip, etc., and accumulations closer to 6″ to 9″.  The question is how far north will the warm-air intrusion move? For now, I’m staying on the conservative side and going with ~9″ to ~11″ of snow, but I will adjust that forecast (up or down) later tomorrow as we get inside the 36-hour window…
Until then, prepare for a winter storm that will start ~7 AM and last all day Thursday into Friday AM (that’s 3 commutes).  Be prepared for multiple closings and cancellations for Thursday…
Disclaimer:
My forecasts should not be used for anything other than general information.
You should not send my forecasts to others without this disclaimer attached
so that there is no chance of misinterpretation by others.  Thanks!Steve
_________________________________________________________________
– Civilization exists by geological consent, subject to change without notice. –