First call for Sunday-Tuesday storm

NAM and GFS are slowly trending colder in the east. 18z NAM shows some bomb potential near Cape Cod at 84hrs. It is looking better for mostly snow, sleet, and freezing rain, but still monitoring potential for a period of plain rain early Monday morning. At this point, main concern is how quickly and how far south the secondary low develops. An earlier (and therefore further south) development would yield nearly all snow and the potential for up to 12 inches here. However that does not look to be the case. GFS and NAM have trended slightly weaker with the initial low which would mean further south and earlier redevelopment. Most trends with these two models have been subtle with no significant jumps in the past 24 hours. Generally a consistent forecast being generated but still potential for slight shifts which could make big differences (to the tune of up to +/-6 inches here). Right now, I like a GFS and UKMET blend. UKMET has been consistent with this storm longer than the GFS. The track is slightly right of the GFS solution and slightly colder. NAM may be coming in good as well: waiting on tomorrows runs for confirmation there.

Precipitation should move into the Keene area by 3pm Sunday. Temperatures will be below the freezing mark (upper 20s dropping into the mid 20s by nightfall) with 850mb temps around -15C. Precipitation will be mainly light especially as it will need to overcome dry air at the surface (evaporational cooling will help us out there with precip type). Snowfall will be around an inch through 7pm. Heavier precipitation should move in by 9pm with mainly snow (possibly some sleet) through midnight. Could see a burst of 2 to 3 inches of snow during this period. After midnight, precipitation type will become more of an issue. Could see a change to freezing rain by 3am with snow and sleet mixing in at times. GFS soundings and DGEX precip maps keep Keene all snow through the storm, but I dont buy that yet. Will likely see a wet 1 to 2 inches of snow and sleet with a glaze of ice. Monday morning will continue heavy precip, but most likely freezing rain and sleet. NWS has rain, and while we could see brief periods of plain rain, it will be mainly ice. Icing up to .1" especially in the valleys. Once the secondary low develops and bombs off the coast, much colder air flows in cutting off WAA. Depending on how far south this develops, snowfall late Monday morning through Monday evening will range between an inch (low develops north), to up to 5 inches (low develops south).

With all possibilities considered snowfall could range from 3 to 15 inches and ice 0 to .5 inches. Going with wintry mix Monday morning and an inch or two of back end snow right now.

First forecast for snowfal 12z Sunday through 12z Tuesday: 4 to 8 inches
First forecast for ice accumulation 12z Sunday through 12z Tuesday: .1 inches