Welcome to the weather blog - a regular Monday through Friday discussion of the weather! You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected]. While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants. This blog is for you, so I hope you enjoy it! -Matt Noyes
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Matt's Quick Weather Synopsis (New!): A cold area of Canadian high pressure will continue feeding chilly air into much of New England. Scattered showers of snow, rain, sleet and freezing rain will continue across Northern New England while the remainder of the area will be cool, gray and watching for patches of ice as temperatures hover around freezing. One to two inches of snow will fall in parts of New England - north of the MA State line - overnight Monday Night. A strong coastal storm winds up southeast of New England Tuesday, bringing coastal wind gusts over 35 mph, the threat for midday coastal flooding, and periodic rain and snow, with a band of accumulating snow through parts of interior New England totaling an additional 1"-3"...likely extending into Eastern New England late in the day where we watch the storm closely for additional accumulation potential Tuesday evening and night. More clouds than sun rule the extended forecast, with snow showers late Wednesday Night into Thursday Morning, and a larger storm of rain and snow Friday.
General Weather Summary: A Canadian area of high pressure is serving as a cold air source Monday Morning, feeding chilly northeast winds southward across Eastern New England and draining cold air into most of the six-state region. While western Vermont southward through Western Connecticut will feel the weakest effects of this cold air drainage, most locales will find temperatures holding steady through the afternoon under gray skies. With temperatures near the freezing mark from Central MA northward, please be cautious for icy patches. Additionally, dense fog will be slow to burn off.
The weather features on the map this Monday morning include a cold and strong area of high pressure north of New England - the source of low-level cold air that's been holding temperatures down in most of New England - and a cold frontal boundary with a developing area of low pressure moving into the Tennessee River Valley. It will be this area of low pressure that all eyes will be focused on tonight through Tuesday night, as it interacts with copious amounts of moisture spilling north out of the Gulf of Mexico and strong coastal storm development ensues.
The ingredients certainly are in place for storm development - the aforementioned moisture and developing storm center associated with a strong bundle of upper level energy moving toward the coastline, and a large difference in temperature producing a clash of airmasses, from highs in the teens across Northern Maine on Monday to high temperatures reaching into the 60's in Southeast Pennsylvania. Riding through this warm and moist air to our south, then directly over New England Monday night, will be a weak disturbance carrying a new shot of increased moisture. The result will be Monday night precipitation - falling as rain in most of Southern New England, but encountering the ample supply of low-altitude cold air from near the Massachusetts state line points north, where one to two inches of snow will fall overnight Monday Night, leaving a slick commute for folks in these areas Tuesday morning.
But remember, this slick and patchy snow-covered Tuesday morning commute for the northern three states of our region will only be the initial surge of moisture riding overhead. To the south of New England, deeper moisture will interact with the strong energetic disturbance for a rapidly strengthening coastal storm through the day on Tuesday. Always important in these situations are the storm track and the amount of available cold air. Both of these have been in question with this storm, and therefore, the challenges have been and continue to be considerable. One of the inherent problems with a forecast like this, is the difficulty our guidance has in seeing and accurately handling shallow cold air like what's moving in today. Often, this cold air is a major player in determining both storm track, and precipitation type, as the clash between incoming Gulf of Mexico moisture and warmth and this cold arctic air is critical in determining the final outcome. At this juncture, we as a meteorological community are still striving to find points of agreement among our guidance and with the real-time, real-world weather pattern that can give us insight to the way this storm will unfold. One fact that seems quite clear is that the storm center will pass southeast of New England, as it rides the boundary between cold and warm air. The other is that is will be strengthening quickly as it does so, feeding off contrasting airmasses to its north and south. The obvious result from this is wind, and a lot of it along the coastlines. This raises a concern for coastal flooding for all east and northeast facing shorelines from the Central coast of Maine southward all the way to Nantucket, where a stiff northeast wind at 20-35 mph with gusts over 40 mph will combine with some of the highest astronomical tides of the season to produce problems at the time of a midday high tide cycle.
In addition to wind, moisture wrapping around the northern periphery of the storm center is likely to spread into New England during the day on Tuesday. As this moisture clashes with cold and dry air still trying to build southward, a band of snow is likely to develop through interior New England - from Central and Western MA through Western and Southern ME (and including most of NH) either side of midday Tuesday. Though removed from the storm center by hundreds of miles, these areas may pick up a couple of inches of fresh snow on Tuesday under this developing snow band. Farther west, it's likely there will be less moisture to contend with and the influence of cold, dry Canadian air will limit amounts to below one inch, while farther east, enough warm air will be in place for precipitation to fall as rain until Tuesday afternoon. As the storm strengthens and gradually pulls east later Tuesday, however, expect colder air to come into play with a changeover to snow around mid-afternoon working southeast from the Interstate 495 belt of interior MA to the coastline through Boston, and by Tuesday evening, to Cape Cod. A quick burst of either side of 3" of snow would be possible after this changeover late Tuesday into Tuesday night. It's also important to note that a significantly larger amount of precipitation is forecasted to fall just offshore, so this storm needs to be watched very carefully, as a northward jog in the track would bring more moisture into New England.
Overnight Tuesday night, as the storm pulls slowly away from New England, winds will remain active from the northwest, and cold air will infiltrate all of New England, keeping ice and snowcover on the roads in many spots. Once this storm pulls east of Nova Scotia, faster flow in the atmosphere can take hold and a fast-moving, weak disturbance will race east into New England later Wednesday. The result will be an increase in clouds after limited morning sunshine, with a few flurries and periods of light snow possible Wednesday night into Thursday morning. Again, in this fast flow with the jet stream winds roaring well above our heads, expect partially clearing skies later Thursday.
By Friday, yet another disturbance will be racing eastward, but this time the jet stream winds aloft that steer our storm systems will begin to buckle southward, allowing the new storm to track southward as it crosses the Lower Mississippi River Valley early Friday. This storm will tap moisture from the Gulf of Mexico, though its final storm track has yet to be determined - the most likely scenario would be a snow north/rain south result to start the upcoming weekend, but with plenty of storms marching across the Pacific, there's a line of storms waiting to move into the Northeast later this weekend and again early next week.
As for the remainder of February, remember what we've reviewed together in these discussions in the past - the abnormal warmth of January and the end of December has resulted in a large amount of available atmospheric energy across the United States. And this warmth hasn't been confined only to New England - most of the nation has been abnormally warm, and therefore most of the nation houses a higher amount of available energy than would normally be present this time of the year. Strong indications are that by the second weekend of February, a significant pattern shift will have occurred across the nation, allowing much colder air that's been locked on the opposite side of the globe and near the North Pole to spill southward into the United States. In this transition, the available atmospheric energy will have to be expended, and large storms are likely to be the result. The question for these will of course be storm timing and track - though with warmth bubbling up from the southeastern U.S., this does favor a track that would put New England on the snowy northern side of storms over the next couple of weeks. Time periods that look to feature potential big bangs to usher in this new weather pattern include this coming Tuesday, then again approximately one week later, on the following Tuesday which may be a larger storm that really marks the change to a new cold and wintry pattern. There are no guarantees and the world of the atmosphere, of course, but certainly the atmospheric signs are that February may begin with a bang, before significant cold may move in for the middle of the month. Time will tell...
Overnight Monday Night Accumulation Map: 
Happy Monday!
Matt
Matt's Technical Meteorological Discussion: Updated Monday, January 30 at 2:05 PM
Lots of weather going on, obviously, and not much time to get all of my thoughts typed out, so bear with me as I try to pack as much in as possible and will write until I'm out of time for today.
Tremendous and classic shallow cold advection example underway in NewEng today with backdoor-type front around backside of departing low pressure center. Heart of cold air north of Maine means business in association with sfc pressure rises, but so does warmth boosting temps into 60's SW CT and NYC area. 20 degree difference in 18-20 miles along this front today. Icy patches remain a concern thru the day in the cool air as standing water from Sun Ngt rain froze early morning with cold air moving in. Inversion in place as a result of the shallow cold dome, tho in some cases multiple inversions existed such as Burlington, VT, who remained 1/4 mile visibility in fog for quite some time before breaking thru. CT River Valley another example.
Warning shot fired across the bow this afternoon at coastal communities. Minor splashover wasn't a big deal with regard to impact, but is when considered this comes with a NNE 8 knot wind, and tomorrow's wind will be closer to 30 kts with churned seas at high tide. NWS Coastal Flood Watch for moderate flood potential certainly warranted - and while the NWS are the ones with the extensive database and correllations regarding coastal flooding, remember that a "moderate" event can have significant impacts to low-lying coastal communities and first-floor/basement businesses and residences.
Initial impulse of moisture aloft comes with a deamplifying southern stream shortwave overnight Mon Ngt and this will result in precip breaking out across interior NewEng. Thermal profile at 850 mb begins quite diffuse and as a result, rain snow line somewhat difficult to pinpoint. That being said, surface and low level cold is impressive and I've been going with a southern weighted blend of the major model guidance, keeping a rain/snow line very close to the northern MA state border. North of this line, should be a uniform 1-2" for the most part - though NAM/GFS/WRF/GGEM all indicate highest amounts to be focused from Western ME to Southern ME/NH and I see no reason to argue with this, so that's where I've centered my 2" amounts. This enhanced precip takes shape along a midlevel 700 mb thermal gradient that will be establishing and will become important later in the forecast period. Farther south than the MA state line, a dusting is possible thru Northern, Central and Western MA as snow should be sloppier and likely to have some rain mixed in. Some freezing rain a distinct possibility, at least early in the precip overnight, as supercooled warm rain process takes hold - that is, subfreezing temperatures are present thru the vertical column, but no temps are cold enough in the saturated layer for active ice nuclei to form, and the result is supercooled water droplets in the lower levels resulting in freezing drizzle and light freezing rain.
Coastal creature to crank up steadily and handily on Tue from 995 mb center at 12Z Tue to 975 mb center at 06Z Wed. First and most obvious result of this will be a strengthening and expanding wind field. Winds sustained 30 knots likely coastline from the northeast and gusts to 50 kts are possible Outer Cape, 40 kt gusts more likely to be attainable other coastal locales of Southern NewEng. Astronomically high tide combines with these winds for coastal flood threat as mentioned above. Winds diminish away from the coastline.
At 850 mb, and to a larger extent at 700 mb, warm advection wrapped around the northern periphery of the storm circulation will collide with cold advection from cold high in Eastern Canada that will be strengthening into Tue. Result will be a frontogenic zone from I-91 corridor of Western MA then hooking NE across NH and into Western ME. Initially, this feature may not be a big player, but thru the day, as midlevel convergence and thermal gradient both increase, this is likely to result in a deformation band thru these areas. Given forecasted passage of storm well southeast of NewEng, total QPF amounts under this band would likely be held to .2"-.3" liquid equivalent, but after early rain, wind shift to north and north-northeast will allow enough cold air to move south so there locations go to all snow by early afternoon, so a couple of inches of snow a real possibility here with a fairly straight 10:1 ratio after the changeover. Thereafter, this frontogenic band will collapse quickly to the coastline Tuesday late afternoon and evening as the deepening storm strengthens ageostrophic flow into its center and thermal profiles cool thru all layers. I would expect this to carry a band of accumulating snow all the way to the coastline - with a changeover sooner than the ptype algorythms suggest - occurring by 00Z the latest at even BOS. With E and NE flow still ongoing at 500 mb, result would be to keep this wraparound band of snow going longer than models are anticipating, esp for the highly populated areas of BOS and Eastern MA, and the potential looks to be there for a solid 3"-4" quick late afternoon thru Tue Midnight snowfall as temperatures drop with northerly wind. That being said, this is largely based on instinct from looking at the synoptic potential for this wraparound quick-hitting, southeast diving band of precip whose back edge will lag behind the low level push of cold advection, and the closest model support I can find is the widespread .10" QPF fairly uniform for these areas of Eastern NH/MA and well agreed upon by the NAM and GFS.
All winds down Tuesday night and though one would think tons of cold air will be available to come rushing in behind the low, a large amount of the cold is in Eastern Canada, east of where low level trajectory will be blowing from. Instead, we'll tap the equally cold air across James Bay, but it has farther to travel and therefore by the time it arrives we're dawning Wednesday and the result is to bring the noticeable chill mainly into Northern/Western NewEng and the hills.
With fast flow, clouds are back in with next shortwave later Wed thru Wed Ngt when some light snow is possible, tho likely mostly confined to mountains given 850 mb ridge cresting over NewEng during the same time period. Thu brings back the sun and in this fast flow it may come back sooner than the afternoon timeframe currently depicted by the guidance, and given a low level SW flow, this would mean I'll have to raise my temps for Thu highs.
Next storm is Fri and right now I'm not optimistic on anything gargantuan with this, although I also can't say the jet stream pattern favors an all-rain scenario. Just flat enough and fast enough that mountains and Northern NewEng may be able to hold on for a snow event. Regardless, I think there's more to get excited about toward the beginning of next week, as discussed in last week's techie discussion.
That's all for today. Enjoy your Monday.
Matt
