Welcome to the weather blog - a regular Monday through Friday discussion of the weather! While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants. I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible. You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is [email protected]. This blog is for you, so I hope you enjoy it! -Matt Noyes
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Matt's Quick Weather Synopsis (New!): We're living life on the mild side across New England for the next couple of days! Southwest winds have ushered in plenty of mild air, so our steady snowmelt continues across the region today as patches of morning black ice melt off and a blend of sunshine and clouds helps to push temperatures into the 40's for most of New England - even nearing 50 in the City of Boston! With these mild temperatures and plenty of snow still lingering around our major metropolitan areas of Southern New England, some poor drainage areas of these big cities will see some large puddles today, so you may want to consider grabbing the waterproof boots if you know your office is in one of these puddle-prone areas! Far northern Maine is closer to bitter cold air locked in Canada, and will only top out around freezing today with periods of light snow accumulating up to an inch. Overnight Wednesday night, a bit of additional moisture moves into New England near the surface, and this is likely to result in scattered areas of fog and black ice. Thursday will be another mild and dry day for most of New England, though snow will develop Thursday afternoon and evening across Northern Maine, where snow will fall heavily at times into Friday. Elsewhere, clouds thicken Friday with downpours, possible thunder, and potentially damaging winds swinging through most of New England Friday afternoon and evening associated with a cold front. Behind this front, arctic air spills in for the weekend with frigid temperatures and a stinging wind. Our next possibility of widespread snow comes toward the middle of next week. -Matt
General Weather Summary: The amazing range in temperature straddling the Canadian border that we examined in yesterday's discussion continues to strengthen as it drops slowly southward for our Wednesday. Bitter arctic air was settling into the Northern Plains, and temperatures from St. Louis northward to the north shore of Lake Superior ranged from 47 degrees to -33 degrees, respectively - some 80 degrees difference! This kind of a tremendous difference in temperature often can serve as a breeding ground for strong storms, and one of these storms will crank up to our west over the next few days, eventually kicking up the winds across New England and yanking down the bitterly cold arctic air that sits north of the border.
In the meantime, however, New England is spending some time living on the "mild side" of life! Early morning patches of black ice continue to give way to growing puddles through the day Wednesday as our snowpack continues to shrivel in the mild temperatures. Those of you who work in the major metropolitan areas of Southern New England and usually find big puddles near your office building in poor drainage areas of the cities may want to bring the waterproof footwear today! Winds will be active from the southwest again Wednesday, though the mild nature of the air will not allow these winds to create much of a brisk feel - most of us will agree the day feels downright mild! With more moist air slowly moving in through the day Wednesday and into Wednesday night, use caution during the overnight period as areas of fog and more widespread black ice is likely to develop on our New England roadways.
Those of you who read regularly have been ready for this brief pattern change - really more of a weather pattern "reshuffling," whereby mild air returns for a few days before we jump right back into a cold and likely stormy pattern. This overall pattern reshuffling comes as the jet stream winds aloft - the fast river of air high in the sky that steers our storms and acts as a thermostat for the atmosphere, separating cold air to the north from warm air to the south - reconfigure briefly. These jet stream winds flow in a wave-pattern across the globe, with ridges (bumps) and troughs (dips). The Eastern U.S. has been in a trough of late, which means New England has fallen on the cold side of these atmospheric winds - and we've felt the results! As the jet stream shifts northward and rises directly over New England for the middle and end of the week, we shift to the milder side of life. With very few strong disturbances for the jet stream to steer our way, the weather will be fairly tranquil for midweek.
Thursday, a stronger storm system will begin taking shape along the clash between cold and warm air, and will move through the Central Rockies and Midwestern U.S. Ahead of this storm, a reinforcing shot of warmth and moisture will stream northward, at the same time cold air oozes southward from Eastern Canada. The result will be precipitation developing along the Canadian border again Thursday evening into Thursday night, and where enough cold air is in place across Aroostook County, ME, snow will pile up several inches Thursday night into Friday! There is still some question as to how far north warmth reaches early on Friday, and a brief change to sleet or rain is possible in these northern expanses of Maine, but most of what falls will be as snow, and we're likely to see amounts nearing a foot in Northern parts of the County.
By Friday, the approaching storm center will bring periods of rain for all of New England, especially during the afternoon, along with gusty winds and one last mild day before a cold front sweeps through. This front may bring a few Friday afternoon thunderstorms with it as it pushes through New England, and bitterly cold arctic air will come rushing in behind this front. The surge of new air may be so strong, that wind gusts exceed 60 mph, and this would mean a widespread damaging wind event for much of New England Friday late afternoon and evening...but we'll continue to monitor this threat and fine tune the forecast with regard to this threat as necessary. In addition to the possibility of rapid freezing of standing water Friday night (dependent upon how much rain falls on Friday), this surge of arctic air will set up a truly frigid weekend for the Northeast, with highs only in the teens for Southern New England Saturday and Sunday, and in the single digits across the north! Winds should be quite gusty on both days, but especially on Saturday, with wind chill values in the single digits south and around or below zero north!
Remember that the mild air this week is truly just a reshuffling of the atmospheric pattern, which means that this bitter blast of arctic air - in my estimation - is a return to reality, and a return to a cold, wintry and at times stormy pattern that will persist until the end of the month, when another brief turn toward mild weather may surface again. In the meantime, there will be a couple of chances for storm - strong indications have been persistent for a storm sometime around next Tuesday, though with a storm track to our south, a snowstorm looks to be in the cards for the Mid-Atlantic, while here in New England we'll be watching this storm carefully, as the northern shield of snow may bring accumulating snow our way, and in addition, the storm will strengthen and turn north parallel to the coast at some point, and how close it hugs the coast will be another factor we'll watch carefully. Chances for snow will continue later next week, as well, so there will be plenty to watch.
Have a great Wednesday!
Matt's Technical Meteorological Discussion: Updated Wednesday, February 15 at 1:30 PM
Short term remains fairly straight-forward. Both NAM and GFS were overdoing the inversion over CT southwest thru NJ significantly in the last couple of runs and I basically ignored this forecast of a strong low level inversion in my forecasts for today. Actual temperatures as of this writing are running about 15 degrees higher than operational model forecast, so thankfully this was the way to go today. Will it be the right correction to make tomorrow as well? A bit trickier given that increasing moisture overnight and slackening winds will allow fog and black ice to develop in many areas, and with an inversion in place (formed due to cold snowpack) it is certainly a concern that we may not mix out on Thursday, but at this point I think we have to remember that we're dealing with a sun angle that's now equivalent to October sunshine, and this shallow moisture should not even build up more than a couple thousand feet, so any low level cloud deck should burn off Thu AM. Thereafter, not much has changed from the technical details laid out here yesterday for vorticity lobe moving across Northern NewEng border and the lift that increases in advance of main shortwave, though there has been a definite northward trend in the baroclinic zone in response to warm advection ahead of the shortwave trough. So now the challenge for Aroostook County becomes just how long we can hold onto snow, and how much precip we crank out - with the NAM putting most of the precip into Canada and the GFS/GGEM holding the rain snow line through Central Aroostook County. At this point, I still would like to buy the colder scenario given the tremendous weight of such deep cold to the north, though I have to admit that with actual highs running above what was expected through most of NewEng today, that tells me to step very carefully for this Northern ME situation. Will stick with the colder scenario for now and re-evaluate Thu.
Elsewhere, Fri forecast has seen some subtle changes in how everything comes together, with the low deepening sooner than previously anticipated, which means the period of greatest intensification occurs farther west. This hasn't changed much from our perspective here in NewEng, except perhaps creating a bit less of a fall/rise couplet along the front when it swings thru. Nonetheless, strong subsidence is still progged immediately behind the frontal boundary and I winds are still progged to be between 60 and 90 knots 850-500 mb, so the threat for a damaging wind event continues later Fri. I still haven't opted to go too far off on this on-air or in the general weather summary above because I want to make sure there are no other trends or changing signals here before really putting folks on guard.
I've made no changes to the weekend temperature forecast for most spots to be in the teens both days, which still is quite clearly frigid. I think guidance is much too heavily weighted by climo and while there will be a downsloping component to the winds, this air is brutally cold and has produced a large area of daytime highs below zero as it's been building in Southern and Central Canada - now being evidenced in the International Falls, MN, areas. Next northern stream shortwave swings thru on Sat and carries a reinforcing arctic front with it, which will bring intense squalls to the mountains Sat afternoon, and a chance elsewhere Sat eve tho downslope flow will fight this potential. Regardless, this backs up yesterday's idea of colder temps on Sunday than on Sat.
Next Tuesday's storm continues to look promising for the Northern Mid-Atlantic and is looking ever more promising for New England to pick up accumulating snow. Ensemble trends show a clear northward drift in the precip probability fields, and more importantly, there's been a shift in some of the Ensemble members and occasional operational runs of varying models (depends on the cycle) to shift the omega block east of Greenland just slightly more westward. Additionally, signs are for a piece of Mexican warmth to break off late this week and travel east along the Gulf Coast this weekend, making its way off the Eastern Seaboard by Monday and Tuesday, which certainly would help pump up a shortwave ridge east of the coast, helping to steer this Tuesday storm farther north. Once again, as with our blizzard when we examined it several days in advance, we can make the argument that the flow aloft is too confluent across the Eastern half of the US, but really a closer inspection yields confluent flow until the East Coast, then a switch to diffluence over the immediate Eastern states. This, combined with the thermal structure and ridge placement near Greenland, have me still believing in the potential of a sizeable storm going from flat juicy wave to potential coastal storm capable of a big dumping for next Tue.
Time will tell, but you and I will be watching closely. That's all for today.