Computer Model Trends: Tuesday evening update

Fred CampagnaFebruary 5, 2013

This post will be updated as the computer model information arrives Tuesday evening into Wednesday morning.

So, have you heard it may snow on Friday?

A few things:

12Z run = 7 am EST initialization time
00Z run = 7 pm EST initialization time
QPF = Quantitative Precipitation Forecast (how much liquid precipitation falls – must convert for snow totals)

GFS, ECMWF, Canadian Ensemble Mean

The mean (average) of all the different ensemble members of the GFS, ECMWF and Canadian models all bring a significant storm to Southern New England. The GFS and the ECMWF take the intense storm over “The Benchmark” 70W/40N – a textbook track for big Nor’easters. The Canadian is a bit farther south.

Canadian Ensemble - a bit farther east than other models — Canadian Ensemble – a bit farther east than other models

GFS Ensemble - Major Nor'easter — GFS Ensemble – Major Nor’easter

ECMWF Ensemble - Historic Nor'easter — ECMWF Ensemble – Historic Nor’easter

Short Range Ensemble Forecast (SREF)

This forecast is based on about 25 different computer model simulations using slightly different parameters to try and come to a consensus as to what will happen in the future. Ensemble forecasting is much more widespread and useful than it was just a decade ago. One way to interpret the ensemble forecast is to come up with a probability of certain criteria, such as snow totals, being reached. The 03Z SREF shows a relatively high probability of at least a foot of snow in Southeastern New England. Notice how it is away from the immediate coast.

03Z SREF 12H snow probability 5pm Fri-5am Sat - 50% chance of 1 foot in some areas — 03Z SREF 12H snow probability 5pm Fri-5am Sat – 50% chance of 1 foot in some areas

SREF members snow totals - notice the WIDE range of solutions, from next to nothing to off the charts. — SREF members snow totals (inches) – notice the WIDE range of solutions, from next to nothing to off the charts.

European (ECMWF)

Whoa, nellie! If the GFS went beast mode at 00Z, I’ll have to find a new way to describe what the 00Z European looks like. The best way to put it is historic, and that’s kind of bothersome considering that it is less than 72 hours from the storm. It takes a 984mb storm to southeast of Nantucket and then slows it down for a bit, so the snow doesn’t end until Saturday afternoon. I need a calculator for the total QPF, which comes out to an astounding 2.94″ in the Providence area – and it’s mainly or all snow!

This isn’t the kind of computer model run that you hope happens, it’s the kind that you frame, put on the wall and hope doesn’t happen. It would be a widespread 18-30″ snowstorm, probably in the top 10 on record, for all of Southeastern New England except the Cape/Islands. I can’t overstate it enough, this is a straight analysis of a computer model, and not an official Right Weather forecast.

The wind would be strong and damaging on Cape Cod, the islands, and probably in RI, too. The height of the storm is from Friday evening through Saturday morning in this computer model run.

The European Ensemble run is also locked in on a major event.