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 linked to the daily forecast at the top of the page, a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow by mid-afternoon. My email is contact@mattnoyes.net. This blog is for you, so I hope you enjoy it! -Matt Noyes
General Weather Summary:
Though the air is certainly plenty cold across New England on Thursday, the core of brutal arctic air will arrive Thursday night and take up residence through Friday. This intense shot of Canada cold will be short-lived, leaving what should be a fantastic weekend for skiing across New England.
Our current weather pattern in the Northeast is defined by a jet stream trough - a dip in the jet stream winds aloft - over the Northeastern United States and Southeastern Canada. Keep in mind that the jet stream is the fast corridor of wind aloft that steers storm systems and acts as a thermostat, separating cold air to the north from warmer air to the south. With a dip in these winds, New England remains squarely on the cold side of the thermostat, and there we'll stay for awhile to come. The result of this deep trough has been to keep strong storms spinning east of New England, and with a powerful storm backing westward through the Canadian maritimes and toward this trough, the counter-clockwise flow of wind around the storm will mean New England sees an increasing north and northwest wind. As winds kick up from the north, cold air has been displaced from central and southern Canada, and has arrived to New England.
This air has brought a certain nip to the air on Thursday with temperatures not surpassing the lower 20s south and about 10 degrees north. Though some sunshine will continue at times after starting the day in many locales, the presence of so much cold air and energy aloft - caught in the jet stream trough over New England - will mean lots of clouds bubbling up through the day with bursts of locally heavy snow at times, with just about all communities equally vulnerable. Early morning squalls already brought slick conditions with numerous accidents on Interstate 95 in Southern Connecticut, and a similar situation will evolve through the day, taking on the look of a summertime thunderstorm day, when scattered activity hits some communities hard with quick accumulations and icing of roads, while others are spared. Though the arctic cold front that brought the initial surge of wind and cold will be pressing farther south away from New England, the westward moving storm from Newfoundland mentioned earlier in this discussion will kick winds up again Thursday night, further enhancing the supply of arctic cold from Canada. This cold air will combine with an increasing wind around the backside of the storm to send wind chill values plunging some 15 to 25 degrees below zero even in Southern New England, while Central and Northern New England will find wind chills as cold as 30 and 40 below zero, respectively - with actual temperatures 10 to 20 below zero north, 0 to 10 below central, and single digits south. This kind of cold is dangerous cold - homeless shelters should expect a busy night, and folks with pets or animals outside should take severe cold weather precautions. At the same time, energetic disturbances caught in the jet stream trough high above our heads will continue to promote snow showers and squalls scattered across New England Thursday night. It also now appears as though the strengthening storm south of Cape Cod Thursday into Thursday evening mentioned yesterday will indeed strengthen just late enough, and just far enough south, to preclude any significant snow at the South Coast other than the aforementioned squalls. A widespread frigid start Friday morning should help to kill any lingering weak car batteries before temperatures struggle to get out of the teens in our warmest locales and won't surpass zero in the north.
Somewhat milder air will gradually ride back into New England on Saturday and Sunday, but with an active flow of disturbances overhead as the jet stream winds aloft begin to move a bit quicker, each of these disturbances will interact with the increasing warmth and moisture to produce a few areas of light snow. One of these periods of light snow is likely to occur with the passage of the first disturbance during the first part of Saturday. The disturbance slated for Sunday looks to be a bit slower in latest guidance, so at this point I'm optimistic on daylight hours of Sunday bringing sunshine and milder temperatures, with thicker clouds and possible light snow more likely Sunday evening or night. Between the light snow Saturday, moderating temperatures and lighter winds, all factors add up well for a great weekend of skiing in both Northern and Southern New Enlgand!
Behind these disturbances, another shot of bitter cold will come early next week, and winter lovers should delight in the fact that we'll remain below to much below normal on average through the middle of February! By the first week of February, the pattern features a narrower corridor of cold slightly farther west from the coastline, which transitions our precipitation pattern from one of potential for blockbuster events, but low probability of them actually coming together over New England, to a pattern more conducive of Northern and Southern stream phasing, which would make storm frequency higher along the Eastern Seaboard. Will it verify? Only time will tell.
Enjoy your Thursday.
Technical Discussion: None today.
Matt
Matt's Technical Meteorological Discussion: Updated Wednesday, January 24 at 1:45 PM
Squalls today assoc with arctic front are delivering near zero visibility in stronger cells and dropping a quick couple of inches for some, which will continue to ice roads. Large part of this intensity coming from increased llvl convergence owing to orography and as arctic front procedes SE and out of higher terrain, squalls will become less intense and more scattered in nature. Even in Central and Southern New England, terrain will still play a role in where strongest cells are located, even if that means the difference between existent and non-existent. Winds gust ahead of and behind front, tho not impressively. Tho there is a strong wind event ahead, it's not a result of this front.
Instead, the upcoming wx will be strongly dominated by the interaction between the digging trof and the retrograding low from Newfoundland. Winds will diminish for a time tonight into early Thu, then pick up again as strong Ern Canada sfc low is drawn westward by southward sinking upper low. The cold pool aloft is quite impressive with this upper level feature - to the tune of -40 C and colder at 500 mb - and this will mean very favorable conditions for convective clusters of snow on Thu across nearly all of New Eng. Additionally, you'll remember the concerns for development of an arctic wave expressed earlier this week and centered on Thursday. Though I don't expect a major event, it does look as though weak wave development will take place along the arctic frontal boundary on the south side of the upper level cold pool, and this will bring a period of steady though most likely light snow to far Southern NewEng - specifically southern CT, RI and SE MA Thursday late morning thru afternoon. Accums should be light tho ratios will be very high, so any slight northward trend in the QPF field as already seen in 12Z runs would have major implications - even a tenth of an inch extra liquid could equate to 3 inches more snow in these areas. I also want to stress that I'm very uncomfortable with this scenario and concerned implications will be greater than what they appear for the South Coast, and especially the Cape and Islands. After issuing this techie discussion, I'll be beefing up the wording in the forecast and General Wx Summary because of the northward trend in guidance, but much more importantly, the delicate and critical setup synoptically. As for the RH and QPF fields, true that there isn't a whole lot to write home about in the operational guidance, but keep in mind that in an arctic airmass - and with an arctic wave - moisture doesn't need to be abundant to crank out accumulating fluffy high ratio snow. The WRF is putting out up to .25 melted on ACK, and this would - if the ratios there resemble what they were in the remainder of NewEng yesterday - equate to over half a foot of snow on the island! Though this is the most moist of the guidance, putting it into perspective with ratio certainly helps to drive home just how fine of a line we walk. As for the synoptic situation I referenced, the vort sliding northeast over the waters just S of NewEng Thu into Thu eve is elongated, but intense, and prompts widespread 500 mb UVM over Srn NewEng latter half of Thu. This puts me on guard for a bit farther N progression of precip that most guidance would suggest, and keeps me very cautious that WRF may be onto something. Additionally, this low should develop very quickly over the warm waters S and E of our South Coast, and probably will appear quite impressive. We saw a storm quickly develop a baroclinic leaf on the south boundary of an arctic airmass with the last outbreak but it was well offshore. This time, my concern is this happens closer to the Cape and Islands given the baroclinicity with warm ocean water and bitter cold air sfc and more importantly aloft, and while it probably still really takes off too late to nail anyone, even getting a northern fringe in its early ramp-up stage would bring a blanket of snow to far SE areas.
Farther north, I don't think we're out of the woods with conditions favorable for convective clusters, as mentioned above. Meanwhile, the pressure gradient will tighten in response to the retrograding storm closing in on Northeastern NewEng, and this will kick winds back up later Thu through Thu night, meaning wind chill becomes more of a factor. The continued cyclonic flow also dislodges the center of the cold air into NewEng - following its upper level polar vortex counterpart - and this will bring some of the coldest air available into Srn Quebec and Nrn NewEng, where high temps on Fri will end up below zero. Prior to that, however, Thu night winds and cold will combine to bring chill factors to 40 below for most of the far North Country, and 20 below in even Southern NewEng! Thu night also poses an interesting scenario weatherwise because it's the time during which the upper level low moves overhead, so I think it's wisest to keep squalls in the forecast in scattered form Thu ngt into Fri, which may affect the AM drive Fri, but given that we're working on uncertainties in the 24 hour window, would rather not get too fancy on this.
Weekend brings two vorts - one Sat AM that should be fairly light in nature for widespread light snow and departs by afternoon, then a more important one Sun AM that has more low level convergence to work with. The 500 mb pattern actually looks great for a progressive but quickly developing storm Sunday, so I'm not sure we should relax much on that wave, tho for now will not go hog wild on it given lack of good support from guidance. Cold shot follows early next week. More thoughts on the longer range tomorrow.
Matt
Tuesday's Discussion:
1:05 PM: No time today before appearance. Bottom line for techies is that we're tracking the meso low (impressive closed signature on sfc/buoy obs and gusts to 38 mph at PVC!) as it moves toward Central Maine coast late tonight and on Wednesday after brushing Cape with perhaps a few fluffy inches Wellfleet to P'town and less farther south, steered by 850 to sfc flow. As it combines with warm advection on Wed, this should really light the snow up around Penobscot Bay where synoptic scale isentropic lift enhances lift already present thanks to convergence and instability. Heaviest amounts of the event may result Wed in these areas. Elsewhere, another fluffy coating - probably less than last night, tho still probably an impressive ratio. Ratios with last event were on the order of 30+ to 1, snow to water.
Matt
Monday's Discussions:
1:50 PM: Update to the techie discussion (previous discussion below): Wow. Radar presentation of developing low off ME coast assoc with Norlun trof extremely impressive - feeder bands as of this writing are evident and sfc obs indicate a circulation that is trying to close. If it succeeds in doing this, and continues to maintain improving presentation, the center of this meso low would have the potential to bring heavy snow if/where it makes "landfall" into the coast of ME.
1:45 PM: Norlun trough event began earlier than I expected today across Srn ME coastline. Passage of morning vort brought widespread snow showers dampened by dry boundary layer but left behind active Norlun trof. Guidance has improved greatly on picking up on these events, but the concern is twofold today: 1) The amount of precipitation forecasted - expected to exceed .50" liquid equivalent, and 2) The location of these amounts, placed over the Gulf of Maine by operational guidance but verifying much farther inland in Northern York County thus far, and developing much sooner than anticipated. Spoke with Kennebunk Police - many thanks for the info - who report snow has been moving farther inland through the day with large flakes accumulating at a steady rate. This isn't surprising given that saturation has occurred in the dendritic crystal growth layer, which in concert with lingering arctic sfc airmass will create a quickly accumulating snow with a high ratio. This is reason for concern, certainly, but is an event that truly is a humbling one for meteorologists. Even though I saw the Norlun trough potential in advance, and see it developing a bit ahead of schedule now, the fact is that we're still largely at a loss as a field regarding where and when this band will drop its heaviest amounts. At this point, given the overwhelming agreement among operational and SUNYSB MM5 guidance that the max precip stays over the waters, I'm going to continue to believe that. Still, in today's noon show I issued an accumulation map with 3" amounts along the Maine coast from Nrn York County all the way to Knox County coast. My reasoning for this was based upon the belief that this band will remain stationary for several hours - perhaps weakening with NVA before strengthening again in response to PVA ahead of shortwave currently moving east across Eastern Great Lakes - owing to very light wind fields in the lower levels, including 850 mb. A west to southwest flow develops later Mon eve, and that's when I expect the band to shift east, though the area of enhanced snowfall rates is likely to expand thanks to increased dynamic lift, hence the reasoning for enhanced amounts all along the Maine coastline. Inland by 10-15 miles, amounts will probably drop to around an inch. Certainly there is some anxiety here, as a verification of heaviest amounts farther north would mean a tremendously higher amount of snow, while a due east shift of the Norlun trough would instead result in the higher amounts staying over water - eventually coming into line with guidance products - and hardly any more than a coating farther up the coastline. So, I've tried to strike a conservative balance to alert folks adequately, yet not overreact, and have tried to emphasize the uncertain nature of this phenomenon in my broadcasts and in the General Wx Summary. It does appear clear, however, that we'll be dealing with this Norlun trof in some way, shape and form through midweek!
Elsewhere, shortwave passage tonight will bring some weak interaction with moisture lifting north from main feed off Carolina coast. This will produce widespread area of light snow, though amounts should total under an inch in just about all spots. Again, some concern along outer Cape Ann and outer Cape Cod for enhancement due to Norlun trough, and have mentioned this in forecasts but not willing to bank on it yet given farther east development and slow eastward progression thus far. Indications are that weak low pressure will develop along the Norlun trof Mon Ngt, and this would mean perhaps some weak ocean enhancement with easterly component in Eastern MA, where not only may highest amounts be observed, but also snow showers may linger into Tue AM. Rest of Tue likely to bring some breaks of sun given midlvl drying, but high llvl RH combined with steadily cooling midlvl temps will create a pool of instability that will breed plenty of llvl clouds and snow showers, esp in orographically favored areas and where Norlun trof effects persist.
Warmest day of the week comes Wed in advance of powerful arctic front. Good llvl WAA to boost temps but also will feed isentropic lift along Norlun trof, and is likely to enhance Central ME coastal snow on Wed as a result. Arctic fropa occurs Wed afternoon and comes with decent llvl speed and directional convergence, which will bring favorable conditions for an active line of squalls in many areas. An event like this is always a bit more tenuous in Eastern Srn NewEng, so would like to see a few more guidance runs before biting too hard, but see enuf with fcstd convergence, PVA, lift, ambient RH and airmass displacement to warrant putting them in the forecast.
Impressive surge of arctic air comes with wild retrogression of Newfoundland storm - as mentioned in General Wx Summary above, this is the same storm that's assoc with Mid-Atlantic moisture today. Building ridge in Greenland forces storm to stall then retrograde as heights lower over Ern Canada behind it. This mean a dump of cold and shortwaves into the trof, which is progged to sit directly over NewEng. With so much energy, and such resultant baroclinicity sitting just S/SE of NewEng, I am so very hesitant to believe this will be a relatively quiet transition. In fact, I don't believe that at all - there should be plenty of active weather through the period, and perhaps the greater question is whether we get a consolidated storm on the base of the trof Thu, over the waters south of NewEng for a coastal storm. While operational models all suggest this will not be the case, a series of GFS Ensemble members do not want to let this potential go. I've kept snow in the forecast, because even if this situation does not produce an arctic wave - which is a real possibility - we should see convective squalls beneath the cold core on Thu, and yet another round of very strong wind and cold Thu that will last thru the end of the week.
Our next wave of low pressure would be likely Sat in response to a Nrn stream wave riding the thermal ribbon laid out across the Nrn Tier of the US.
Enjoy your day!
Matt
