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:
The passage of a dying cold front has marked the leading edge to cooler weather - but we won't feel the immediate results in most New England communities on Tuesday. In fact, the temperature drop behind this front is lagging far behind, awaiting a push of north winds out of Canada to move southward, and leaving mild air with a northwest wind behind - a rare circumstance! The northwest wind also means that our mild airmass will progress no farther north than it already was early Tuesday morning - across Central and Southern New England - leaving more clouds than sun and a cooler day in the north, with a blend of sun and clouds and much milder temperatures Central and South. Eventually, cooler and drier air will envelope all of New England.
Tuesday's winds out of the northwest will provide a "downsloping" wind that slopes down off the mountainfaces and hillsides for a lot of lower elevation communities of New England. With mild air in place, very little cool air streaming in, and a steady downsloping wind that will push air into lower elevations, thereby allowing it to warm and dry upon descent, sunshine will break through the deck of low altitude clouds for most of Central and Southern New England from late morning onward. The combination of warming strong late-March sunshine with downsloping winds will push some Southern New England locales into the 70s Tuesday afternoon while Central New England rises into the 60s. Farther north, sunshine will come in the form of breaks between clouds as Northern New England straddles the boundary of warm and cool air, awaiting the arrival of new Canadian cold, and the limited sun will hold temperatures in the 50s. Though there will be little to focus showers or thunderstorms at the surface by Tuesday afternoon, there will be a warm airmass in place at the same time a moderate strength upper level energy center rides over Southern New England, and this may trigger a few Tuesday afternoon showers and thunderstorms in Southern New England.
The next big feature on the weather map will be a southward sagging cold front across Quebec, heading south toward New England. This front will represent the leading edge to a hearty shot of cool air in place across Central Canada, associated with a large and strong high pressure cell that will be expanding over Hudson Bay, Canada, and moving gradually southeast. As the high pressure cell grows, its reach of clockwise airflow - and therefore northerly winds on the east side of the cell - will increase, driving the next installment of cold air into New England from north to south overnight Tuesday night, bringing gradual and marked clearing for one and all. Though this air will have a better hold of New England on Wednesday, it will truly be a slow bleed southward, and therefore temperatures probably won't reach their coolest period until Thursday. This will leave a gorgeous day of sunshine for midweek thanks to the steady supply of dry air from Canada and a northerly wind, with temperatures certainly cooler than Tuesday but still running above normal for the date, which would be close to 50 degrees as a New England average. After a cool night Wednesday night, expect the coolest day of the week's end to come Thursday, as Canadian air will be squarely in place across the six-state region with winds picking up in speed from the northwest as a strong storm cranks up in extreme Eastern Canada while the nearby high pressure cell weakens, though still remains strong enough to exert its influence, especially when resulting in a big pressure difference from the Eastern Canada storm.
The expansive high pressure cell will lock dry and cool but pleasant conditions into New England through Friday, when a few high altitude clouds will increase late. All the while, the jet stream pattern aloft for the end of the week will feature one major upper level storm over Eastern Canada - associated with the aforementioned surface storm that will help to keep cool, dry air in and our winds cranking later in the week - and another slug of significant energy moving east out of the Eastern Pacific and across the Rocky Mountains into the Central United States. This type of a pattern, with two very strong disturbances over a relatively short distance (Rockies to Eastern Canada isn't far in the scope of the global atmospheric scale), is referred to as an "amplified pattern" because the dip in the jet stream with each disturbance is quite pronounced, creating large undulations in the jet stream winds that steer our storm systems and act as a thermostat for the atmosphere, leaving deep troughs of unsettled and cool weather very nearby to cresting ridges of warmer and fair weather. With such an amplified pattern by the end of the week, this will mean a rapid transition to a milder regime by Saturday, likely followed by at least some showers if not a more meaningful rain for the end of the weekend. This amplified pattern, however, will likely lead to its own demise, as cool air dragged down from Canada by each strong disturbance will beat down the ridging warmth, resulting in the development of a more stable, flatter pattern for the United States next week, though a pattern that's likely to bring cooler air to the northern tier of the country, and especially to the Northeast for part of the first week of April.
Looking forward to the warmth tomorrow afternoon - see you back here tomorrow!
Matt
Matt's Technical Meteorological Discussion: Updated Monday, March 26 at 1:15 PM
Clouds and precip come courtesy of isentropic lift coupled with leading vort max ahead of primary vort moving across Great Lakes. First vort max brought multiple CG lightning strikes even tho light rain for a time, then the boundary layer moistened. We're in a similar situation tho without the lightning for Nrn NewEng as I write, which makes sense given decreased llvl speed convergence and decreasing theta-e gradient. Still, as air becomes more saturated, elevated instability increases and Wrn NewEng may see thunder before the day is out. Farther south, slug of warm and moist advection has been less focused thus far but still will be sufficient to generate sct shra and then dynamic lift assoc with and ahead of main vort max this eve and tonight will be enuf to generate widespread shra, downpours and isolated tsra perhaps from Wrn MA to CT. Wind shift early Tue truly is a trof rather than a cold front at its leading edge, tho I suppose technically it's still a cold front, just with the temp gradient lagging far behind. The airmass change is lax in coming south because it must wait for the eastward movement of the high over Hudson Bay, which happens but not until later. This actually means the passage of the wind shift favors more warming than otherwise in Srn NewEng as winds turn from the northwest and downsloping kicks in, warming many locales of Srn NewEng into the 70s as this downsloping helps to break up deck enuf for sun. I know RH progs are very high, but that's similar to what we're seeing upstream in OH Valley today and tho clouds are numerous, sunshine is effective and temps have been soaring. We're likely to see the same result in Srn NewEng on Tue afternoon after morning fog and low clouds that will be stubborn, with deck hanging until late morning when wind shift kicks in a bit. Still, we're looking at a wind shift line/front that doesn't completely clear Srn NewEng, and a few extremely weak mesoscale waves of low pressure will develop along it. This slight lowering of pressure, along with the warming interior, is likely to favor a sea breeze for almost all Southern NewEng coastal locales, whereas BOS may not get over 56 or so degrees before the sea breeze initiates, while LWM hits 70. A bit trickier on the SCoast of CT where GON may go to 62 or so and then fall back, but stronger NW gradient flow in HVN argues for mid 70s! Weak vort max Tue afternoon/eve may spark a thunderstorm in CT with sfc based LIs approaching 0.
Wed thru Fri brings installment of fresh, clean, dry and cool Canadian air. High amplitude pattern flow suggests quick warming on Sat, and perhaps several degrees above normal, before rain event to end the weekend and cooler air to begin April.
Matt
