Thursday, January 23, 2014

Deep Winter Cold and Snow threats Roll on

An energetic disturbance from central Canada rotating around James Bay upper level low will dive into the northern US and form a strong broad low pressure center over the Great Lakes early Saturday morning. A strong cold front trailing from low pressure will bring with it periods of light snow and snow squalls into Southern New England midday to late afternoon and evening from west to east during Saturday. Behind the front is a renewal of arctic air along with gusty northwest winds. Ahead of the front a south/southwest flow will develop and bring potential for wind gusts over 30 mph to perhaps as high as 45 mph for east and southeast shores. This will temporarily bring some *milder* air into extreme southeast SNE and would mean a mix of rain and perhaps wet flakes at the tail end late Saturday. 

 There are good signals that many areas in SNE could pick up a coating to 1" of snow from these snow showers/squalls with the potential of 1-4" over northwest Mass, the Berkshires and northwest CT. Not a huge amount of snow but will become a bit hazardous for travelers caught out in it in combination with the wind. This will create low visibility at times. Keep this in mind if you have traveling plans Saturday. Temperatures are certainly looking a bit milder during the day Saturday than it has been in recent days with highs in the upper 20's to low 30's but crashing quickly with the projected frontal passage approaching.  Weak high pressure builds in Sunday with the cold front offshore and high temperatures back into the teens for many ! Winds will still be a bit gusty on Sunday but this time from the west in the wake of the frontage passage. Wind chills will be below zero for much of the region. Yet another disturbance will dive southeast out of central Canada early Sunday rounding the upper level low that will shift close to Hudson Bay at that time. This disturbance has a shot to bring some more snow showers and gusty winds into the region very late Sunday into Monday morning, but confidence a bit lower with this shortwave feature. Beyond this, the deep arctic winter cold chugs on with temperatures remaining well below normal and we make make a run at some record cold as well mid to late next week. There will be the potential to watch for a close brush with a large ocean storm late Tuesday into Wednesday but at this time I feel as though this is a near miss. The upper level pattern seems to not dig enough and go negative in time to take building southeast moisture up the coast, therefore appears to take the bulk out to sea. Its certainly is something keep an eye on at least though.   ~Anthony 
Below is a snow map for Saturday. Click on the image for a larger view

Wednesday, January 8, 2014

Temperatures Moderate Ahead of a Wet & Windy Period Sat-Sun

   After what appears to be the coldest start to January for much of Southern New England since 1996, the jetstream is now retreating off to the north and temperatures are slowing moderating at both the surface and aloft as we approach the weekend. Much needed relief from the cold for many for many reasons.
   The next weather system will approach us from the Ohio River Valley. It is a weak clipper like disturbance and moisture starved but with cold enough air in place at the surface and aloft briefly, we could see a period of wintry precipitation early on Friday which is more and more looking like some light snow which could coat the ground for a few locations at best. Not a huge deal. After that temperatures will continue rise both aloft and at that surface ahead of our next weather system which will be a developing storm low pressure system over the Great Lakes. Ahead of that storm off to our northwest the jet stream winds (fast flowing river of air about 30,000 ft above our heads) will be screaming from the south/southwest. With the absence of a cold high pressure t the north this will bring in a surge of moist and mild air up into SNE and boost temperatures into the 40's to near 55° for many Saturday .
Showers will be on the increase Saturday morning from WSW-NNE across the area with heavier showers & downpours arriving during the afternoon and especially the evening.
   The other issue is the potential for damaging wind gusts Saturday evening and overnight into Sunday. Upon its approach and ahead of the storm system, winds about 5,000 ft above our heads (850mb) will increase to between 60-80 kts. Its is not always the case that these strong winds aloft are brought to the surface without sufficient mixing like sunshine, but this go around looks to coincide with convective like showers and possibly even some thunder Saturday evening. This would pull some very health wind gusts to the surface and that becomes a problem as of course we have the Patriots at home for their Playoff Game Saturday eve and also brings the potential for scattered tree & power line damage especially east of the Worcester area up and down SNE and favored higher elevations and Cape Cod and The Islands. Given all these factors its safe to say wind gusts could be 40-50 mph with isolated gusts to 55 mph.  We will surely have to keep close tabs on this as we approach. As far as rainfall goes, anonymously high precipitable water values will lead to heavy downpours at times into Sunday morning and it appears as though we are looking at a widespread 1-2" rainfall from this event. With frozen rivers from the recent cold this may bring some flooding issues.  One other concern is large swells building along south shorelines Saturday eve to 10-15 feet and looks to last right through all of Sunday too. Will have to watch for a bit of splash over, minor coastal flooding at times of high tide for those south facing shorelines of Southern New England . Colder air comes rushing in here for Sunday, then things become a bit complex as to whether we stay mild through next week or the jetstream dips back south again. This should become much clearer after Saturday. Thank you for taking the time to read this, I appreciate it !   ~Anthony