You know me; I don't exactly shy away from aggressive and confident calls (arrogant/confident same difference). A Nor'easter 5 days out? #Lockitin. Superstorm Sandy? Left hand hook for the win. But NORLUN troughs, well, they scare me a bit...they are SO fickle in their placement yet so powerful. (Consider them the pit of snakes to my Indiana Jones)
But hey, I'm going to take a shot at nailing this thing down anyhow. First let's talk about the rest of today.
Today: Mostly sunny skies will see increasing clouds from southwest to northeast by late in the afternoon. Otherwise the big story is the cold, coastal locations are in the low 20s but most of Maine is stuck in the teens and single digits with wind chills feeling well below zero in many spots.
Tonight: The focus is on the development of the NORLUN trough and the exact placement of it. (One more time- A NORLUN trough is basically a narrow band of heavy snow that develops in a weakness between a storm out to sea and an upper level disturbance to our west) I think snow starts breaking out over coastal NH and coastal York County by 9-10 PM this evening. At first it will fight off dry air at the surface so the snow will be light, however it will eventually saturate the column of air and moderate snow will commence after midnight. Several inches of snow should accumulate from Hampton, NH to Wells, ME and about 40 miles inland from both of those locations by the morning (probably 2-4"). The snow will be much lighter just outside this "Strike Zone" which will extend northward through Portland to about Bath. (1"-2" by morning) North of this I don't expect very much in the way of snow overnight. For the rest of the state...not much going on actually, mostly cloudy and cold with lows in the single digits.
Tuesday: The NORLUN lifts a bit to the north and intensifies so look for moderate to heavy snow from Portsmouth, NH to Biddeford with lighter snow in Portland and north to Wiscasset. This snow setup continues through the early afternoon before the trough breaks down and pulls out to sea. Final accumulations should be in the 5-10" range in a narrow coastal area from Portsmouth to Kennebunk, 3-6" from Kennebunk to Freeport and then 1-2" through the southern Midcoast. (Since it will be so cold at all levels of the atmosphere look for VERY fluffy snow) Now I realize this doesn't currently match the map on our website but, due to a scheduling error, I'm writing this from home right now and can't change the graphic until I get into the office. Disclaimer alert: If this trough sets up even 20 miles further north Portland could get crushed...that's what's scary. Once again if you are outside the strike zone for the NORLUN, it will be mostly cloudy, cold and quiet.
Back to sunshine but brutally cold temperatures for Wednesday and Thursday. Wednesday looks like the coldest day with highs not hitting 15 even along the coastline and staying in the single digits for most. Overnight lows will be dangerously cold with -20 F possible in the mountains and foothills and below zero readings the rule rather than the exception on both evenings.
A more statewide snow event looks pretty likely on Friday night into Saturday. There's still a chance it stay a bit too far to our south, but otherwise it looks like a healthy 4-8" type event for us.
Ok I'm out of here. I'll keep you update on the NORLUN and the Friday storm on here and via Twitter (@KeithCarsonWCSH).