A long duration storm

Sun has broken out over western New England as the lead shortwave moves east of the region. Expect clouds to increase again this afternoon as the northern shortwave digs southeastward.

Water vapor imagery indicates an intense storm developing in the Gulf of Mexico. Rain and thunderstorms have overspread northern Florida in association with this system. The storm will move northeastward out into the open Atlantic this evening and strengthen slowly.

As the northern system digs, the two wave will phase, allowing for an upper low to develop and deepen just southwest of New England. The phased energy will trigger rapid strengthening of the surface low during the day Saturday. The upper level pattern will pull the surface storm system westward, back toward New England, as the surface pressure bottoms out, near 960mb in the Gulf of Maine.

The primary question is how far southwest will the surface low retrograde. The primary target for heavy snow is much of Maine, where the storm will be driving 50kt northeast winds transporting moisture in over the land. Back across western and central New England, winds will be more northerly, and not as moisture laden.

An inverted surface trough extending westward from the low will initiate enough lift to generate light to moderate snowfall across much of New England Friday Night through Sunday. Most of the region will pick up at least 4" from that alone. Further east, the wound up storm will deliver some heavier snows, where at least 6" is likely.

For the Keene area, expect 4" to 8" totals, spread out over 48 hours.

The winds may turn out to be the primary concern. A very tight pressure gradient will develop over New England, between a 960mb low, and a 1040mb high to the northwest. Gusts to 40mph are possible over western New England, with 60mph gusts possible further east.