Chaos Theory in Action

What a mess. Over the last week to 10 days, there's been very little, if any agreement among and between our computer models regarding the outcome of the upcoming week to two weeks. This has wreaked havoc with the forecast and made being a meteorologist somewhat painful. That being said, let's try and bring some clarity to everything.

Nationally, we have one storm entering California, bringing some rain and mountain snows to the region (generally light). A larger storm is moving across the center of the country bringing heavy rain and t'storms to parts of the south-central states, with heavier snow across Kansas, Missouri, Southern Iowa and Illinois. This heavier snow is going to move into S Michigan and parts of Ontario.

That storm will weaken. A secondary storm is going to spin up off the Southeast coast. Out ahead of this, some light to moderate rain should swing through the Mid-Atlantic on Tuesday morning. As it lifts north into the mountains of Northwest NJ and the Poconos, it may fall as some snow initially for a few hours. For New York City and Long Island, it may briefly start as snow as well, before transitioning to rain.

Beyond this point, all mayhem breaks loose. Let me give you a blow by blow account of the models through Wednesday evening...which are actually in somewhat decent agreement on the outcome, though they differ with the details:

NAM Model: Transitions the low offshore a little furthe and swings back heavy precipitation into Connecticut, Rhode Island and the Hudson Valley. A process known as "dynamic cooling" seems to occur and transitions a mix of rain and sleet over the Hudson Valley and CT over to mostly snow. Heavy snow lifts through Albany and into the Adirondacks as most of Connecticut changes back over to rain. Lake enhanced snow develops in Central New York and heavy snow lifts into the Berkshires and Green Mountains. Heavy snow continues in the Upper Hudson Valley and parts of Vermont/NH through Wednesday evening as the center of the storm pivots away and no real cold air pile drives in. I tend to think this solution is a bit too warm, so I wouldn't buy into it right now entirely. That said, total snowfall through Wednesday evening would be > 12" in the hills west of Albany and the eastern Adirondacks, Berkshires, Greens and S Whites in NH. Amounts greater than 6" would fall east of I-81, north of I-84 and W of I-495 in the Boston Metro. Unfortunately, this model only goes out 84 hours, so what happens beyond Wednesday evening is a mystery. But again, I don't have much faith in this model for this sort of intricate setup.

The NAM is a higher resolution, focused model. There are a number of global models that forecast for, obviously, larger areas and are thus lower resoluton. Let's examine a couple of them.

The GFS: Starting Tuesday afternoon as that low slips away, moderate snow is being shipped back into the Hudson Valley and New England. The rain/snow line goes roughly from Hazleton, PA-Danbury, CT and holding steady as the low deepens, but no true cold air ramps in. Through Tuesday evening, snowfall of > 6" falls in the eastern Adirondacks and Berkshires, with 3-6" north of I-84, east of NY SR-12 (Binghamton-Utica) and west of I-91 up to southern Vermont. Through Wednesday morning, light snows continue in the Poconos, far north NJ and the Catskills, north through the Adirondacks and Green/White Mountains. The rain/snow line is roughly from Boston-Hartford. Generally light snow continues all day Wednesday, with heavier precipitation approaching the coast by Wednesday evening, as the storm sits about 300-400 miles off the Massachusetts coast. Snowfall by Wednesday evening is > 12" for the eastern Adirondacks, parts of the Catskills and southern Green/White Mountains. Snowfall greater than 6" is similar to the NAM... east of I-81, N of I-84 and W of I-495 in the Boston Metro.

The European Model: This model's data is tough to interpret at times, as there is limited amounts available. But it keeps the general idea of the other models, with heavier precipitation closer to Boston and slightly lighter amounts in NY, VT, and SW NH. Heavier snows (~8") fall in a stripe from Oswego-Monticello, NY. Total snowfall in the Adirondacks and Hudson Valley would be about 2-4" less than the other models. The biggest difference is that it has a tightly wound up storm sitting just offshore of Boston, whereas the GFS strings it out and keeps it offshore by 300 miles.

So by Wednesday evening we have a very intriguing weather map. Both the GFS and European models, while differing on specifics in New England, are in agreement on an area of moisture in South Florida, in response to that storm currently moving ashore in California. Some good upper level energy is swinging across the Gulf, with a strong upper level storm centered over Northern Indiana. Let's examine what the GFS and Euro do from Wednesday evening through Friday evening:

GFS: This model takes the Gulf energy, rides it up the East coast and phases it into the upper level storm sliding out of the Midwest. This develops another coastal storm off the Southeast, which sends a generally light band of snow from DC through NYC and then power-bombs the storm off of New England and slides it back inland, sending heavy snow into Western New England and eventually overspreading most areas north of the Mason-Dixon line. The storms do what we call a "Fujiwhara," where they basically rotate around each other before phasing and bombing out. The storm finally exits on Saturday afternoon. Total snowfall Friday morning is over 12-18" for most areas west of I-495 in MA, N of I-84, east of NY SR-12, and southwest of Maine. An additional 4-8" is possible during the day Friday and Friday night. A major storm for the Adirondacks, Catskills, Berkshires, Greens and Whites, with the bullseye somewhere likely in the Adirondacks or east of Albany.

Euro: The European actually slides the storm over Boston back over Upstate New York, while the energy from the Gulf slides up the East Coast, further offshore than the GFS. The new coastal storm spins up well offshore, does a Fujiwhara with the system over New England and then phases Thursday night, but about 300 miles further northeast than the GFS. The storm backpedals toward the coast before zipping back out to sea Saturday evening. This still dumps heavy snow in the interior, but considerably less than the GFS does. While the GFS suggests a widespread 12-24", the Euro spreads things out a bit and suggests a widespread 6-12"+ in Western NY, 12-18" in Central and Eastern New York, and 12-24" in the Berkshire, Green and White Mountains through Maine.

So the summary: This actually isn't terrible agreement, all things considered. But the devil is in the details. So the outlook right now is for heavy snow for the mountains of New England, with lesser amounts in low elevations and only minor amounts from Boston-DC. A couple notes: This is a good setup for shadowing. With a persistent easterly flow, east facing mountain slopes will end up getting hammered, while the valleys on the western side end up getting shadowed. This poses trouble especially in the Hudson Valley from Kingston through Albany. It's possible that the Taconics, as well as the higher elevations east of Albany end up with 18-24", while Albany itself "only" ends up with 12". This can also shaft the Binghamton area and areas of Otsego County, downwind of the Catskills. However, the persistent northerly wind can mean bonus lake enhanced snow for places like Rochester through Syracuse. So stay tuned.

A little longer out...

A potentially major storm will crash into California this coming weekend. This morning, the models want to agree that Southern California will take the brunt. As this storm slides east, it should develop into a potentially major, major storm for parts of the East around March 3rd. Stay tuned.