March 5, 2003
While it will be tough to get snow to stick in places where
temps are in the 40's and pushing 50 today, it is apparent that there will
be a period of moderate to heavy snow after some rain for parts of the
Northeast. What was once looking like solely a Middle Atlantic event is now
knocking on the doorstep for parts of New England also. As I stated in a
discussion a few days ago, the storm last week (the miss) was a fluke in
that it went against the seasonal trend and was drier and farther South than
most guidance had progged. With that being said, it appears that the wave of
low pressure which will develop along the old frontal boundary tonight will
follow a similair pattern of most other systems that we have seen this
season in that each successive run of guidance is wetter and farther North
and West with QPF.
Take for instance the 5/12z MM5 at 30 hours:
12Z MM5
Redevelops low pressure near Hatteras in response to relatively strong
(1022mb) high pressure nosing into the Northeastern US. 540 line is crashing
Southeastward changing rain to snow throughout central and most of Eastern
PA. Even the -2C 850 line is South of PHL right along the Mason Dixon line.
The 5/12z NGM is almost an exact match:
12Z NGM
Moderate snow into NYC by noon on Thursday! Quite a change from 12-18 hours
ago. Again, places like PHL and especially DCA are still right on the line
and timing will be a big issue whether or not precip can hang in there until
the colder air infiltrates or vice-versa.
5/12z ETA is probably overdone, but it has done the same thing several times
this year and been correct:
12Z ETA
Moderate to heavy snow falling in central PA, northeastern PA, and into NYC
and lighter snows edging into Southern New England. All the while, -2C 850
line and 540 line still crashing South. Again, PHL and DCA will be a tough
go with temps near 50 today.
FWIW, the Canadian is in equal agreement, but lacks a 30hr panel, so I did
not use it to compare for this reason alone. While I don't think this will
be a major event, especially given mild temps today for many and a quick
moving system, areas into Central and Northeastern PA all the way to NYC and
perhaps S New England could be in for a surprise.
Another factor against big snows is the time of year is the time of day when
the majority of precip will be ocurring. The reason I am so intrigued by
this "event" though, is because back on Feb 5, 2001 we had a similair setup
in the Northeast where rain changed quickly to heavy snow and we received 8"
of snow which snarled PM commuters that weren't expecting the change. Should
be an interesting day for some on Thursday.
S.B.
