February 25-26, 2006 Snowfall: Initial Estimates

[donsutherland1]

A clipper-type system will likely track east to east-southeast from central New York State across southern Connecticut and then to near southeast Massachusetts or Nantucket during the February 25-26 period. This trajectory is a little to the south of that provided by the 2/24 0z and 6z runs of the GFS.

Several factors lead me to make this adjustment:

∙ The block continues to build:
2/22: -0.115
2/23: -0.493
2/24: -0.771

Moreover, the NCEP 500 mb height anomalies now show the above normal anomalies across northern Greenland peaking at 4 to 4.5 standard deviations. Hence, there is at least a hint that the block might be a little stronger than earlier suggested.
∙ Recent runs of the GFS ensembles are showing somewhat of an increased likelihood of an east-southeast trajectory for the system. The NCEP ensemble mean 500 mb height anomalies have consistently depicted a system that would dive to the east-southeast. The growing trend among individual ensemble members for such motion may well reflect the growing downstream block.
∙ The NAM has grown a little wetter (2/24 12z vs. 0z).
∙ The 6z ensemble mean brings 0.10” qpf across northern New Jersey, southeast New York (including New York City) and Long Island. A few ensemble members even bring 0.25” to that region.

In a worst-case scenario, this clipper could well dive just south of Long Island before slowing regaining a somewhat north of east trajectory. That’s a fairly low probability, in my view. Still with the recent trend in the ensembles, it’s one that will need to be watched.

Initial Estimates (2/25-26 Totals):
Albany: 2”-5”
Boston: 3”-6”
Burlington: 2”-5”
Concord: 2”-5”
Hartford: 2”-4”
New York City: 1” or less
Newark: 1” or less
Philadelphia: 1” or less
Pittsburgh: 1” or less
Portland: 1”-3”
Providence: 2”-5”
Worcester: 2”-5”

[weathermom]

1" or less.......it's a very sad thing.

[donsutherland1]

Weathermom,

Worse, for your area and mine (NYC suburbs), the lowest end will probably have a greater chance at verifying than the 1" figure. Still, the potential for possibly a moderate to maybe significant event for the first week in March still exists.

[donsutherland1]

Verification:

The area of snowfall was farther north than I had anticipated. Hence, in such cities as Hartford and Providence, I overestimated the snowfall and underestimated it in Concord.

From 2/24/2006 10 am:
Albany: 2”-5”; Actual: 1.9"; Error: 0.1"
Boston: 3”-6”; Actual: 2.5"; Error: 0.5"
Burlington: 2”-5”; Actual: 2.8"; Within range
Concord: 2”-5”; Actual 6.4"; Error: 1.4"
Hartford: 2”-4”; Actual: 0.3"; Error: 1.7"
New York City: 1” or less; Actual: None; Within range
Newark: 1” or less; Actual: None; Within range
Philadelphia: 1” or less; Actual: None; Within range
Pittsburgh: 1” or less; Actual: 0.8"; Within range
Portland: 1”-3”; Actual: 3.0"; Within range
Providence: 2”-5”; Actual: 0.4"; Error: 1.6"
Worcester: 2”-5”; Actual: 2.0"; Within range