1/27-28: Possible Significant Accumulations in N. MA & N

[Stephanie]

Thanks again Don, SF, KOW and FLguy for your insight to these storms.

Generally, when the secondary low does form off of the DE/NJ coast, we tend to get screwed in this area because it is just forming and most of the moisture seems to be to the north already. If it's off of the Carolina coasts, we'll be in better shape.

[donsutherland1]

David,

I believe the precipitation will likely end as some snow in Pittsburgh. Unfortunately, I don't believe a significant accumulation is likely Tuesday night or Wednesday. Tonight should see an appreciable 2"-4" locally 6" snowfall.

Edited for P.S.

I just saw that FLguy answered your post. I believe he may have a better feel for Pittsburgh (not to mention his expertise), so I would place far greater weight on his ideas for Pittsburgh.

[FLguy]

THanks flguy! Does significant mean more than 4". What do you think of the first guess map from wxrisk. It has pittsburgh in the ice storm zone

DT does an excellent job. as the initial low runs into the lakes, strong warm advection will kick in and warm the column significantly, thus the icing threat. now once the energy transfer takes place, the cold air will be drawn in rapidly behind the deepening coastal low resulting in the re-cooling of the column and a period of heavy snow perhaps.

[Chris the Weather Man]

STORM DESCRIPTION FEB 5th 2001 http://www.njfreeways.com/weather/05-Feb-01.html
An intensifying low pressure that helped generate its own cold air produced heavy snow over most of northern New Jersey and accumulating snow as far south as southwestern New Jersey.

Synoptic Discussion
The low pressure developed along a stationary front just east of Florida on the 4th. By the morning of the 5th, it moved northeast to near Elizabeth City, North Carolina. It then intensified rapidly (25 millibars in 24 hours) as it moved northeast, reaching Long Island on the evening of the 5th and Nova Scotia on the morning of the 6th.

Local Discussion
Precipitation moved into New Jersey around 2am EST on the 5th. Temperatures were cold enough in Sussex, Warren, Morris and northern Passaic counties so that precipitation started as snow, while across the rest of the state it began as rain. As the morning progressed, the intense precipitation caused temperatures to cool as snow aloft melted into rain, which absorbed atmospheric heat in the melting process. This caused the rain/snow line to progress slowly but steadily southeastwards through the morning and afternoon hours. Precipitation had changed to snow by 10am EST on the 5th in Somerset, Hunterdon, western Union, western Essex, southern Passaic, and northern Bergen counties, by 11am EST on the 5th in southern Bergen, Hudson, eastern Essex, eastern Union, Middlesex, and Mercer counties, and by 1pm EST on the 5th in Monmouth, northwestern Burlington, Camden, and Gloucester counties. The heaviest snow fell between 1pm EST and 5pm EST on the 5th in northern sections and more briefly around 3 pm EST on the 5th in southern sections. Accumulations were 16 to 20 inches in Warren and Sussex counties, 10 to 18 inches in Huterdon, Morris, and northern Passaic counties, 6 to 12 inches in Bergen, southern Passaic, Essex, western Union, and Somerset counties, 3 to 6 inches in Hudson, eastern Union, Middlesex and Mercer counties, and 1 to 4 inches in Monmouth, northwestern Burlington, Camden, and Gloucester counties.
From Ray Winter Storm Archive.

[jdt]

2-4" Southern half of coastal NJ (east of GSP)
4-8" SE PA, Southern NJ South of 195
6-12" NYC metro, LI, NE NJ, Central NJ north of 195, Extreme SE interior NY and Coastal SW CT
12"...+? NE PA, NW NJ, Interior SE NY, Interior SW CT

Precip types:
2-4" area is rain to mixed precip 1st half of event then snow.
4-8" area: Eastern half is mixed precip 1st third of event then snow.
4-8" area: Western half brief mixing early then snow
6-12" area: South & East portion 1st quater is mixed precip then snow
6-12" area: North & West portion brief mixing then mainly snow
12"...+? area: All snow

[donsutherland1]

Just a quick note...

The 0Z ETA, GFS, and GGEM are all very encouraging with respect to the possible significant snowfall.

[donsutherland1]

Per the 12Z runs of the GFS and ETA, things continue to look good. I'm somewhat concerned that Philadelphia and southern NJ could have dry slot problems if the secondary intensifies to the extent being shown on the ETA. Totals across northern NJ (EWR and northward) and southeastern NYC might need to be pushed up somewhat. Later guidance will be helpful.

[Guest]

Don, my neck of the woods, Central PA (dead center of the state), is an intriguing forecast problem. I think 4-8, what's your thoughts?

By the way, great post as always.

[nystate]

What about Central/Northern NY? NWS is saying 6-12 for us is possible, but no watches out yet..

[donsutherland1]

Jamie,

I believe 4"-8" out your way sounds reasonable.

[donsutherland1]

Nystate,

It depends on where you're located. For example, I'm thinking 4"-8" for Albany and 8"-14" in Poughkeepsie.

[donsutherland1]

After an exciting day of model runs, including the 12Z ETA's massive snowstorm to its 18Z stinginess, it appears that a loose consensus of models is evolving.

Basically, it appears that some of the initial ideas drawn against the backdrop of earlier model guidance coupled with a look at some historic synoptic patterns have stood up well to the shifting sands of today's model forecasts.

Some refinements are in order given a slightly more east of north orientation than I had assumed, but those are not all too significant. At this time, I believe likely snowfall amounts for the January 27-28 storm will come out around:

Boston: 8"-14"
New York City: 6"-10"
Newark: 4"-8"
Philadelphia: 2"-4"
Providence: 6"-12"
White Plains: 6"-12"
Worcester: 8"-14"

All said, I believe the 1/27 0Z run of the GFS and the 1/26 12Z run of the ECMWF offer a reasonable range of solutions on which one can base the forecast. At the end of the day, no big surprises were in order.

[VortexMax]

Nystate,

It depends on where you're located. For example, I'm thinking 4"-8" for Albany and 8"-14" in Poughkeepsie.

Agreed.

[donsutherland1]

Per the 12Z ETA and also radar, the ideas expressed last night (refined from a day earlier) are still looking good.

With regard to the start of the event, somewhat milder air has been working its way up the Coast overnight and early this morning courtesy of the primary storm.

Therefore, at least some sleet is likely in NYC at the onset and a mixed bag is likely in Philadelphia.

Select 13Z sounding results:

New York City:
700 mb -6C
780 mb -4C
850 mb -2C
920 mb -7C

Philadelphia:
700 mb -4C
780 mb -2C
850 mb -2C
920 mb -4C

These readings are somewhat higher than they were 12 hours ago and some further increases are likely into this evening before the thicknesses crash after around 8 pm in NYC and maybe 10-11 pm in Philadelphia.

All said, northern New Jersey, southeastern and central New York, Connecticut, Rhode Island, and eastern Massachusetts (including Boston, Cape Cod, and Nantucket) still appear to be in for a significant snowfall of 6" or more. A foot is likely in some spots.

[donsutherland1]

Based on the position of the secondary storm's development (somewhat farther south and east of what I had anticipated), I now believe that the heaviest snows will probably fall across southern New England, southern New York (including Long Island), and northern New Jersey.

I have adjusted my expected accumulations to reflect this development:

Boston: 4"-8"
New York City: 6"-10"
Newark: 6"-10"
Philadelphia: 2"-4"
Providence: 4"-8"
White Plains: 6"-12"
Worcester: 3"-6"

For most of this area, soundings continue to support some sleet with the snow but no serious freezing rain problems.

[Chris the Weather Man]

I am still going with 12-16 inches, West of NYC.. 20 miles west....

[RU848789]

Wiith everyone else now saying 5-10" or so for the NYC metro region (including 20 miles west), what prompts you to go with 12-16"?

[Chris the Weather Man]

Wiith everyone else now saying 5-10" or so for the NYC metro region (including 20 miles west), what prompts you to go with 12-16"?

Well, Remember, they are being conservative, and, DT Final Call, NYC, is in the 10 inches, 18-25 miles west, is in the 12+ range.......

[donsutherland1]

Verification of my final forecast on the 1/27-28 storm:

<b>Final Forecast:</b>
Boston: 4"-8"
New York City: 6"-10"
Newark: 6"-10"
Philadelphia: 2"-4"
Providence: 4"-8"
White Plains: 6"-12"
Worcester: 3"-6"

<b>Final Totals:</b>
Boston: 1.5" (Bust: 2.5" below the range)
New York City: 10.3" (Bust: 0.3" above the range)
Newark: 7.0"
Philadelphia: 3.1"
Providence: 3.9" (Bust: 0.1" below the range)
White Plains: 9.5"
Worcester: 4.6"

The New England busts were worst of all given the dramatic reductions from the initial idea that were made.

[Stormsfury]

Verification of my final forecast on the 1/27-28 storm:

<b>Final Forecast:</b>
Boston: 4"-8"
New York City: 6"-10"
Newark: 6"-10"
Philadelphia: 2"-4"
Providence: 4"-8"
White Plains: 6"-12"
Worcester: 3"-6"

<b>Final Totals:</b>
Boston: 1.5" (Bust: 2.5" below the range)
New York City: 10.3" (Bust: 0.3" above the range)
Newark: 7.0"
Philadelphia: 3.1"
Providence: 3.9" (Bust: 0.1" below the range)
White Plains: 9.5"
Worcester: 4.6"

The New England busts were worst of all given the dramatic reductions from the initial idea that were made.

Actually, Don, only Boston was the one you missed on the low side and I don't call a 0.3" and a 0.1" difference, a bust, by any means ... Excellent numbers vs. verification, and excellent job ...

SF