It looks as if I’m going to be working from home tomorrow: the first serious snowstorm of the year is headed our way. As usual, the geek in me prefers to get this forecast in metereologist-speak, straight from the NWS Taunton Forecast Discussion (my emphasis):
THIS WILL NOT BE A VERY DEEP LOW WITH SFC PRESSURE JUST BELOW 1000 MB BUT COUPLED WITH HIGH PRES TO THE N WILL RESULT IN VERY STRONG ENE GRADIENT WITH IMPRESSIVE ATLANTIC INFLOW. IT WILL ALSO BE A SLOW MOVER AS IT GETS CAPTURED BY UPPER LOW RESULTING IN LONG DURATION OF PRECIP AND HIGH WINDS ALONG THE COAST TUE/TUE NIGHT.
NAM/GFS AND EVEN REGIONAL GEM ARE SIMILAR WITH QPF TUE/TUE NIGHT OF 1-1.5" SE NEW ENG...0.5"-1" VCNTY I-90...BUT SHARP CUTOFF N OF PIKE DECREASING TO LESS THAN 0.1" ACRS S NH. ...
Note that QPF denotes the precipitation measured as liquid water. The challenge with a storm like this is to translate QPF into snowfall:
SHARP QPF GRADIENT AND PTYPE ISSUES WILL MAKE FOR VERY DIFFICULT SNOW FCST FOR TUE. PARTIAL THICKNESS PROFILES SUGGEST PRECIP CHANGING TO MOSTLY SNOW ON TUE IN THE INTERIOR NW OF I-95 INCLUDING BOS AREA BUT THIS IS NOT A SLAM DUNK NEAR I-95 AS THERE IS A HINT OF WARM AIR ALOFT WHICH COULD AFFECT SNOW ACCUM IN THIS REGION. ... CROSS SECTIONS SHOW BEST SNOW GROWTH NEAR MASS PIKE FROM BAF-ORH-BOS ALONG WITH STRONG BANDING SIGNAL IN DEFORMATION AXIS. ...
GFS SNOW AMT TOOL INDICATING OVER 12" IJD-ORH-BOS AND EVEN 10" PVD BUT DUE TO UNCERTAIN THERMAL PROFILE AND QPF GRADIENT DECIDED TO TONE THIS DOWN AND GO WITH 4-10" IN THE WATCH AREA WITH HIGHEST AMOUNTS NEAR OR JUST S OF MASS PIKE. ...
WINDS WILL BE A CONCERN WITH THIS STORM AS 50-60 KT NE LLJ REACHES S COAST TUE MORNING PERSISTING INTO TUE NIGHT.
So although the official forecast says “New snow accumulation of 6 to 10 inches possible”, we see that this is the result of interpreting the output from a tool that’s predicting over 12 inches! We’ll see…. And the forecast of high winds suggests that power outages are likely; time to check batteries in flashlights. (I also tend to bump up the thermostat program before a storm like this, so as to keep the house a few degrees warmer than usual.)
UPDATE 5:48pm: Well, the forecast seems to be changing rapidly. Latest prediction is for just 2 to 4 inches of snow, with more ice and sleet. The heaviest snowfall is now predicted to hit Smithfield in northern Rhode Island – 8-12 inches. I wonder how it will actually come out…..