2/22-23/2007 Snowfall Estimates

[donsutherland1]

Over the next 36 hours, an energetic system will race from southern Manitoba to a position just south of Cape Cod. Afterward, it will track east-northeastward from there. As it does so, it will be deepening and will likely gain some Atlantic moisture so as to provide 0.25” to 0.50” precipitation across the southern half of New England, with the highest figures occurring in southeastern New England. Northern New England will likely see little if any snow given the storm’s track.

If the system were to bring all snow, it would provide a moderate snowfall to the affected region. However, warmer air at 900 mb to the surface will need to be worked out before the precipitation falls as snow. Hence, a cold rain is likely for at least part of the event. Nonetheless, snow-starved southern New England should see some accumulations before the developing system departs.

At this time, taking into consideration that the developing system’s dynamics could help accelerate the change to snow e.g., at Providence, my initial estimates for the 1/22-23 timeframe are as follows:

Albany: 1”-3”
Boston: 1”-3”
Hartford: 2” or less
New York City: 1” or less
Providence: 1”-3”
Syracuse: 2”-4”
Toronto: 1”-3” (2.5 cm to 7.5 cm)
White Plains: 1” or less
Worcester: 1”-3”

There remains the possibility that a small area running from about New London to Worcester to Boston and down to Providence could see more snowfall than what I’m thinking in my initial estimates.

[tropicana]

woohoo..thanks for including Toronto!



-justin-

[donsutherland1]

After examining the 2/21 18z and 2/22 0z guidance, I believe most of my figures remain on track. As such, the only change I'm making is to reduce Boston to 2" or less from the initial idea of 1"-3". It appears that the heavier precipitation will pass to the south of Boston. Boundary layer issues remain real and therefore snowfall amounts around the NYC Metro area will likely be very low (1" or less).

My estimates for the 2/22-23 timeframe are as follows:

Albany: 1”-3”
Boston: 2” or less
Hartford: 2” or less
New York City: 1” or less
Providence: 1”-3”
Syracuse: 2”-4”
Toronto: 1”-3” (2.5 cm to 7.5 cm)
White Plains: 1” or less
Worcester: 1”-3”

It remains possible that a few places might see somewhat heavier snowfall. If changes are required, I'll make them after the 12z guidance.

[donsutherland1]

The clipper remains on course to bring a period of accumulating snow to parts of Pennsylvania, New York State and New England. However, it still appears that the warm boundary layer will ensure that the New York City Metropolitan area will see little in the way of accumulations.

Some 12z temperatures at 925 mb to 975 mb:

Hartford:
975 mb +0.5°C
950 mb +1.3°C
925 mb +0.7°C

New York City:
975 mb +4.0°C
950 mb +3.3°C
925 mb +1.5°C

White Plains:
975 mb +3.1°C
950 mb +2.7°C
925 mb +1.6°C

Given the current soundings across the region, I believe a little more in the way of snow will likely fall in Hartford. Increased qpf also suggests a greater snowfall for the Albany area. In Hartford, snow:liquid ratios likely won't be impressive.

My final estimates for the 2/22-23 event are:

Albany: 2”-5”
Boston: 2” or less
Hartford: 1"-3"
New York City: 1” or less
Providence: 1”-3”
Syracuse: 2”-4”
Toronto: 1”-3” (2.5 cm to 7.5 cm)
White Plains: 1” or less
Worcester: 1”-3”

[tropicana]

As the Clipper came through Toronto this morning, visibilities dropped to near zero, and snow was quite heavy, arriving in Toronto just in time for the morning commute to work and school. Very large wet flakes, and accompanied by lightning and thunder. Apparantly caused sporadic power outages with the weight of the heavy snow on transformers.

Quick accumalations of 3-5 cm in the space of between 90mins- 2 hour period. Noontime temperatures rose up to 40F 4C and that has helped in melting a lot of the snow from this morning, but temperatures are expected to plunge later on today.

[donsutherland1]

Verification:

From 2/21 2:00 pm

Albany: 1”-3”; Actual: 2.6"; Within range
Boston: 1”-3”; Actual: 0.5"; Error: 0.5"
Hartford: 2” or less; Actual: 1.6"; Within range
New York City: 1” or less; Actual: None; Within range
Providence: 1”-3”; Actual: 0.1"; Error: 0.9"
Syracuse: 2”-4”; Actual: 0.8"; Error: 1.2"
Toronto: 1”-3” (2.5 cm to 7.5 cm); Actual: 1.4" (3.6 cm); Within range
White Plains: 1” or less; Actual: Trace; Within range
Worcester: 1”-3”; Actual: 3.9"; Error: 0.9"

From 2/22 12:30 am

Albany: 1”-3”; Actual: 2.6"; Within range
Boston: 2” or less; Actual: 0.5"; Within range
Hartford: 2” or less; Actual: 1.6"; Within range
New York City: 1” or less; Actual: None; Within range
Providence: 1”-3”; Actual: 0.1"; Error: 0.9"
Syracuse: 2”-4”; Actual: 0.8"; Error: 1.2"
Toronto: 1”-3” (2.5 cm to 7.5 cm); Actual: 1.4" (3.6 cm); Within range
White Plains: 1” or less; Actual: Trace; Within range
Worcester: 1”-3”; Actual: 3.9"; Error: 0.9"

From 2/22 10:30 am:

Albany: 2”-5”; Actual: 2.6"; Within range
Boston: 2” or less; Actual: 0.5"; Within range
Hartford: 1"-3"; Actual: 1.6"; Within range
New York City: 1” or less; Actual: None; Within range
Providence: 1”-3”; Actual: 0.1"; Error: 0.9"
Syracuse: 2”-4”; Actual: 0.8"; Error: 1.2"
Toronto: 1”-3” (2.5 cm to 7.5 cm); Actual: 1.4" (3.6 cm); Within range
White Plains: 1” or less; Actual: Trace; Within range
Worcester: 1”-3”; Actual: 3.9"; Error: 0.9"