As one in the unsilent minority that finds snow unpleasant, VERY expensive
to deal with in my business and an aggregation, I ³enjoy² looking for signs
that the upcoming winter storm will take it relatively easy on me snow-wise.

I have been watching the two major models (the nam and gfs) and have noticed
that they have both trended warmer over the past few runs. In fact, if I
take the new nam (formally the ETA) as gospel, this will be mainly a rain
event for us here in Framingham/Ashland area and Boston as well at least
till mid tomorrow afternoon.

Specifics:

(1) This model outputs lots of water about 1.5², so if it were to be all
snow, we would get about 15² of very, hard to move snow. However, several
snow vs. rain parameters strongly suggest that we will not changeover around
here until mid Thursday PM. By then, lots of the 1.5² will have already
fallen.

(2) The 1000 - 500 mb thickness until mid PM is 5,400 meters+ and the 1000
- 850 mb thickness is 1,300+ until then at least mid PM.. The 1000 - 500 is
the thickness of the layer of the atmosphere from just above me to about
18,000 feet, while the 1000 - 850 is the thickness from just above me to a
little less that 5 K feet. As these layers warm, they expand, as they cool
they contract. Thus, thicknesses reflect the²average² temp of the layer in
question. The 5,400 meter threshold indicate that rain is just as likely as
snow, while above that figure, rain becomes more and more likely, while
below 1,300 meters, likelihood of snow increases dramatically. The 1,300
meter acts in like manner*.

(3) For frozen precip, we like to see the temperature at 850 mb (again a
little under 5,000 feet) to be below freezing (aka below 0C). This does not
happen until mid/late tomorrow PM according to nam model.

(4) These, and other parameters, taken individually do not assure rain vs
snow, but several taken together help seal the deal for rain.

I have found it troubling (or for me untroubling) that there is little/no
sign of cold high pressure to our north. Without this feature, storms are
not blocked and tend to move much closer to S. NE coast which translates to
warmer. Furthermore, lack of frigid high means lack of cold feed.
(Compare this to synoptic conditions at Blizzard 2005!)

By the time it could around here, only about .4 or .5² melted remain (light
precip over many hours) so we get 4+² around here?

Warnings-I am not a meteorologist and only attempt forecasts as a hobby.
This is only a semi confident stab at reality. It may well pan out, but
then again... I have not seem the newest gfs model so am basing the above
solely on the nam model. However, the gfsl as well has trended warmer and
warm. Also, remember that this is location specific. NW of 495 should be a
very different story!)

Jot in Ashland, MA

*Using, pressure thickness formula, the ³average temp² of 1,300 meter
1000-500 thickness layer is approximately 0C.


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