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 contact@mattnoyes.net. This blog is for you, so I hope you enjoy it! -Matt Noyes
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Matt's Quick Weather Synopsis: Clouds and periods of rain will linger across most of New England Wednesday, as the same ocean storm that's been sending moisture our way for the last 36 hours continues to pivot Atlantic moisture off the ocean and ring it out as showers and periodic downpours. Though the heaviest rainfall will set up across the Connecticut and Pioneer Valleys today, all of us will contend with periods of rain through the day, along with morning fog in Eastern areas. Far Northern and Eastern Maine will fair the best and brightest, with some sunshine likely to appear Wednesday afternoon, boosting temperatures into the 60s. Elsewhere, clouds will linger and fog will redevelop Wednesday night before winds shift to the south and southwest and help to break up the cloud deck on Thursday. It will be a slow process - leaving plenty of clouds mixed in with the sunshine - but any sun we see will be very helpful in warming the atmosphere. A weak cold front will bring a few showers Thursday night, but drier air will team with sunshine to boost temperatures on Friday. The weekend still features some uncertainty in the forecast, but with a strong upper level disturbance rotating through, chances are good that morning sunshine gives way to developing showers or rain - especially later - on Saturday, with a breezy and brisk day on Sunday with a few lingering showers in Northern and Western New England. -Matt
General Weather Summary:
Midday Update for Tsunami Warning for Fiji and New Zealand: An earthquake of roughly magnitude 8, a major quake, has struck in the Tongan Islands, in the Western Pacific. The fact that this earthquake occurred beneath ocean waters means a tsunami is possible, though not certain. Because of this potential, the Pacific Tsunami Warning Center has issued a Tsunami Warning for Fiji and New Zealand through 5:55 PM Eastern Daylight Time. Because this blog is not a real-time, worldwide natural disaster site, I won't be providing continued updates, but those of you with interests overseas in these locations can access the NECN website for updates at www.necn.com. Additionally, you can find the full tsunami warning text here: http://www.prh.noaa.gov/ptwc/wmsg -Matt
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Our stagnant weather pattern rolls on, with the ocean storm that's been sitting off the New England coastline continuing to pivot moisture inland across New England from the Atlantic. To the west of New England lay splendid spring weather, and slowly but surely we will finally get a taste of this fine air to end the workweek.
In the meantime, bands of rain will continue moving from east to west across eastern and central New England, merging with an ongoing band of rain that has persisted through the Connecticut River Valley and the Pioneer Valley. Under this band of rain, over half an inch of rain will fall today, while the remainder of New England should see under half an inch with the conveyor belt of moisture that's been streaming in off of the Atlantic finally weakening as the storm center southeast of New England gradually weakens and shifts farther east. Nonetheless, bands of showers and rain will continue to pivot through New England through most of the day, diminishing in intensity noticeably after lunchtime Wednesday, however. Other weather factors will be diminishing as well - winds will blow out of the north and northeast but only at 5-15 mph, for example. The diminished winds will help to calm the seas a bit, but only a bit as persistent onshore flow from the past several days has really churned the waters and 6'-12' seas will continue. Morning areas of fog in Eastern New England and on the coastal waters will continue to lift, though restricted visibility in showers and fog will continue through the day.
With plenty of moisture lingering and winds subsiding Wednesday night, expect fog to redevelop, and some areas of drizzle will be possible, as well, though showers should end by midnight. The trend for Thursday will be for some drying as winds gradually shift out of the south and southwest, helping to break up the low-altitude deck of clouds that will linger early in the morning. While this wind shift occurs well in advance of an approaching cold front, and not only helps to clear out the lower levels of the atmosphere but also pumps warmer air into New England, plenty of energy and moisture will still linger aloft. What this means is that most of New England - especially Central and Eastern New England - are likely to find plenty of clouds in the middle and upper levels of the atmosphere mixing in thorughout the day. This would limit just how warm our temperatures will be able to climb, though given that this airmass has a history of producing highs in the 70s to our west the last few days, even limited sunshine should boost most areas to near 70 degrees. With a relatively light wind flow, it's probable that coastlines will stay cooler as a sea breeze circulation develops.
Two cold fronts will take aim on New England for the end of the week - both will be reflections of upper level energy centers moving eastward in the jet stream winds aloft. The first disturbance will cross New England Thursday evening and night, and will be relatively weak, as will the surface cold front associated with it. This front is likely to bring a few showers to New England as it moves through, and though the air behind it technically is cooler, we're unlikely to feel the results of this cooler air on Friday. Part of the offsetting factor will be a westerly wind that establishes behind the front, and for most of New England, a west wind is a drying and warming "downsloping" wind as the air slopes down off the hills and mountains of Northern and Western New England. The combination of plentiful sunshine and a downsloping wind will help to push many areas into the seventies, though cooler temperatures will be found in the hilly and mountainous terrain.
The next cool front will swing through New England Friday night into Saturday morning. Following this front will be an extremely strong disturbance dropping southeast out of Canada in the jet stream winds aloft. Given that this front will be nearby, and the strength of the incoming disturbance, I have to believe that the forecast I've had going of showers and rain developing later Saturday is still the most likely scenario. As mentioned earlier this week, there has been plenty of uncertainty with this weekend forecast, largely due to the strength of the incoming disturbance, and its effects depending heavily on the speed it moves east, and how it interacts with the passing cold front. Still, it appears to me as though a *dry start* to our Saturday will likely give way to *developing showers* as a storm center strengthens just off of our coastline in response to the incoming energy center. There is enough energy available for this storm to really strengthen Saturday evening over the Gulf of Maine, and this would wrap around bands of heavy rain into especially Northern New England Saturday night, though we'd all be vulnerable to rain bands later Saturday into Saturday night. This also means the seas would kick up once again after finally calming down a bit at the end of this week. By Sunday, the surface center of low pressure would wrap underneath the primary disturbance aloft, settling over Northeastern New England, and keeping Sunday showers in the forecast for Northern New England, with building puffy cumulus clouds but a breezy and mostly dry day farther south. I'll continue to watch this for you, and if it looks more optimistic I'll be sure to keep you posted, but for now...no change to the outlook from earlier this week.
Have a wonderful Wednesday.
Matt
Matt's Technical Meteorological Discussion: Updated Wednesday, May 3 at 11:45 AM
Yesterday's sideways T-shaped pattern of rainfall was indicative of moist conveyor belt feeding into low-level front and this same trough remains in place - though farther west - today, as evidenced by heavier band of rain in zone of enhanced isentropic lift from Central CT coastline up Interstate 91. This will continue to be the area of heaviest precip until it begins to deteriorate this afternoon as a result of negative Theta-E advection at 700 mb. Still, in this band of rain over .50" QPF expected while remainder of area will find lesser amounts. Some impressive QPF values from last 30 hours with amounts of 3.87" Portland, ME, 3.65" from wx observer Peter Dawson in Portsmouth, NH, 2.27" from Don Towle in Manchester, MA, but as of this writing, still only .01" storm total in Danbury, CT!
With plenty of low-level moisture and weak upward vertical motion in the boundary layer, lighter showers should continue thru midnight with drizzle filling in as well as fog, as surface airmass advecting southward out of North Country will actually be slightly warmer and more moist than lingering cool pool in Southern New England, and this will favor maintaining a moist environment. As wind direction shifts gradually, atmosphere will gradually dry out, first as isentropic lift decreases and showers taper after midnight, then as mixing gradually begins on Thursday. Still, I have concerns about just how much sunshine we actually can see on Thursday, as wind flow through 700 mb is 10 knots or less! This will make the aforementioned mixing a VERY gradual process, and with lots of moisture still lingering through about 600 mb, it's going to be difficult to get the clouds out of here. This means the low-level deck will have a difficult time burning off, and once it does, a mid-level deck will still linger which is likely to allow some sunshine given dry air above 600 mb, but plenty of Cu and Ac are likely to remain, and this will cut back on max temp potential. Additionally, with light wind flow most coastal locales should set up sea breeze circulation. Still, this airmass is a mild one that will warm handily with just a little sunshine, which is why I'm still pushing average temps to near 70 many areas.
First cold front that comes thru NewEng Thu eve and night likely to bring some showers with it given strength of vort max dropping ESE with 20+ units of vorticity providing moderate vorticity advection and associated height falls. Behind this front, mid and low level airmass is noteably cooler but this shouldn't matter much with regard to Friday's temps, which are likely to exceed Thursday's prefrontal maxes for a few reasons. The obvious one is that there will be no sea breeze with westerly wind taking hold. Combination of downsloping and mild airmass of 925 temps 12C or better with 850 temps around +6C would produce highs in the lower to middle 70s with full mixing, though decent lapse rate will keep mountains and hills cooler.
From this point onward the forecast turns quite tricky, though my thoughts remain the same as they were earlier this week for the upcoming weekend. That is, I acknowledge that the forecast is one of low confidence given the speed of the jet flow coming over NewEng, and as a result the timing of the incoming vort max. But I still think the same synoptic scale thinking is important here, which is that a second cold front crosses NewEng Fri night. This front just barely clears NewEng Sat AM but this happens at the same time the strong upper vort digs SE across NY State. The question becomes whether this vort continues digging and can prompt surface cyclogenesis, or if the flow is too broad to allow the vort to dig and keeps a relatively flat progression thru NewEng. The American guidance - as of this writing the GFS and even the incoming 12Z NAM - both support the flatter solution which would deliver a nice weekend for one and all. But in the GGEM, the Canadian Ensembles, the ECMWF, the ECMWF Ensembles, and the GFS Ensembles I still find a strong vort forecasted to prompt cyclogenesis along the NewEng coastline during the day Sat with a strengthening low pulling north into the Gulf of ME later Sat and into ME on Sunday. This fits the solution you and I played out in this discussion earlier in the week, wrapping the surface low under the upper low over Northeastern NewEng on Sunday, leaving lingering showers in the North Country and likely bringing downsloping flow to limit building Cu to a mainly dry but breezy and cool mixed sky with perhaps some sprinkles or light rain showers at diurnal max heating with instability aloft.
After this weekend there are still a few periods of significant uncertainty, though also a few things we can hang our hat on. One overall theme for the coming week and a half after this weekend is for an above normal temperature pattern aloft, even at 850 mb. Good agreement on this in the Ensembles, and with rising heights and a developing southwest flow in the the mid and upper levels, there will be plenty of warm air aloft. I think the real question here is what we can do at the surface - after a dry Monday another strong vort dives across NewEng into the mean trof position just off the coastline, and surface low development looks like a possibility south of NewEng by Tuesday, though it's not yet clear how far south. Nonetheless, this may keep the deep warmth from coming into NewEng, especially given that a surface boundary is evident on MSLP plots of both GFS and ECMWF Ensemble members, and also means another rain event if development is close enough in. By the end of next week, however, broadly diffluent flow is from the WSW which would mean above normal temps with plenty of embedded vorts - some tapping southern moisture - in a diffluent flow that would favor rounds of showers or thunder sliding thru periodically. Mild weather should reign until next strong vort middle of third week of May drags attendant strong cold front thru followed by cooler than normal and dry airmass heading into third weekend of May.
Enjoy your day!
Matt
