Now THIS is living! Fantastic, dry, Canadian air has taken hold of all six states, and those who enjoyed the pleasantly perfect weather on Monday will get a repeat Tuesday, and another beauty on Wednesday, with temperatures nudging up ever so gradually through the period. Though warmth and humidity will build briefly later this week, another push of dry and pleasant air from our neighbors to the north will set the stage for a fantastic start - and perhaps a good finish, too - to the extended Labor Day Weekend.
Clear skies and nearly calm wind Monday night allowed for ground fog to develop, and as expected, this fog was dense early Tuesday in some spots. With high pressure (fair weather) cresting overhead, winds are extremely light through several thousand feet of the atmosphere, including right here at ground level. The result is an exceptionally slow process of burning off near-surface moisture, meaning it takes an extended period of time for areas of valley fog to lift into a layer of low clouds, then evaporate slowly from the outside edges inward. Nonetheless, by midday all areas will be bathed in sunshine, and the dry nature of the air will allow for at least some vertical mixing of the atmosphere - a stirring of the lowest few thousand feet caused by "thermals," or rising pockets of warm air due to heating of the land by the sun - and that will aid sunshine in quickly raising temperatures into the 80s from Canadian border to South Coast by Tuesday afternoon, even with a generally light wind. In fact, the light prevailing wind and lack of any dominant weather feature other than our large high pressure system will mean the development of sea breezes Tuesday, keeping coastlines about 6-10 degrees cooler than inland communities. While thermals may provide pcokets of rising air in the lowest few thousand feet of the atmosphere, above these thermals the air is sinking - the trademark of a high pressure system and the opposite of the deep rising motion needed for the development of clouds and precipitation. This will help to lock sunshine across New England Tuesday afternoon, and provide another clear and cool night Tuesday night, with temperatures perhaps just a bit milder than Monday night owing to warming temperatures aloft and a gradually increasing southerly wind.
Though Wednesday morning may not be quite as cool as its predecessor, areas of valley fog and patches of low altitude clouds are possible once again during the early morning, before dry air again wins out for a mostly sunny day. There will, however, be a few differences in the atmosphere - both at the surface where winds will blow from the southwest around the backside of the departing high pressure system, in its clockwise flow of air around its center, and aloft where warmer air will continue spreading into New England. All the while, there will be a series of upper level disturbances
traversing the Great Lakes, propelled by the jet stream winds aloft on
Wednesday, and the result of these disturbances will be rounds of
thunderstorms over the Eastern Great Lakes, Ontario and perhaps Western New York State,
sending a few high altitude clouds east across New England with only a slight chance of late Wednesday afternoon or evening
thunder in Northern Maine, closest to the parade
of energetic disturbances.
Of course, each disturbance that spins north of New England will
provide a bit greater tug on cooler Canadian air aloft, and that
southward seeping of cool air will also be reflected at the surface.
The leading edge to this new airmass - a cold front, by definition -
will settle southward into New England Wednesday night into Thursday,
taking its sweet time to cross Central and Southern New England later
Thursday and Thursday night, allowing most of these communities to jump
well into the 80s and perhaps some spots even around or over 90 before
the cooler air - evident with noticeably cooler temperatures in
Northern New England in the 70s Thursday afternoon beneath thicker clouds - settles south Thursday night accompanied by a
few continuing rain showers and thunderstorms. Yesterday I discussed some of the uncertainty associated with the Thursday forecast, focused upon cloud cover and corresponding
temperatures. Latest information continues to indicate I should stay the course with the going forecast of sun and clouds
with increasing heat and humidity and potentially strong afternoon and
evening thunder in Southern and Central New England, and cooler, cloudier conditions in
the North Country. That said, the speed of this front is still going to be an achilles heel in the forecast, as the next step is determining how quickly the front can clear Southern New England on Friday. With this slowing front, it's entirely possible that showers or thunder will still end up in the forecast for Southern New England - especially far Southern New England - on Friday, while drier air muscles in with clearing skies from north to south. In all likelihood, the best chance of any new scattered showers popping up on Friday would be along the South Coast, while the remainder of New England should end up with a day that becomes less humid and fairly pleasant.
Behind the cold front, cooler and drier, very pleasant air will
return for the start of the Labor Day holiday weekend. In
fact, for those of you trying to make some early plans for the rest of
the holiday weekend, it appears to me as though this shot of drier air moving into place on Friday will only gain further footing in New England for
Saturday, for a dry, pleasant and sunny day. By Sunday, we'll see only an extremely gradual return of deeper warmth and moisture to the Northeastern United States, and while a few clouds may stream overhead, it's unlikely that showers would get any closer than Western New York State. By Labor Day Monday, a better chance of showers and
thunder return to the forecast, but these may end up being only
scattered afternoon storms, primarily in Northern and Western New England in warm and increasingly humid air ahead of
an approaching cold front. That's something I'll work to fine tune in
the coming days.
Enjoy your Tuesday!
Technical Discussion: With such quiet and straight-forward weather, technical discussion probably not needed today. Enjoy the day!
Matt
The 2006 calendar year, according to the National Oceanic and
Atmospheric Administration (NOAA), was the second warmest year since
record keeping began in 1895, ranking only behind 1998, which was a
mere .08 degrees Farenheit warmer. At issue since that reading has
been whether El Nino played a major role in the warm temperatures, as
the presence of El Nino certainly had a major effect on Atlantic
Tropical activity. Though there was some speculation that the presence
of El Nino may have been a significant contributor to the warm
temperature anomaly, most in the meteorological community were aware
that El Nino has never, in the past, made such a significant
contribution to national temperature, adn though warmer average
temperatures can be observed during El Nino periods, the amount of
warming is usually a fraction of what was observed in 2006. After
completing a recent study, a group of scientists at NOAA have done an
in-depth analysis of the heat of 2006, and determined that not only was
El Nino a small contributor, but that a combination of natural cycles
and greenhouse gases played a major role - with greenhouse gases likely
accounting for more than half of the widespread warmth across the Lower
48 states. Click here to access the press release from NOAA. A summary of the report by the Associated Press can be found on the CNN website, by clicking here. -Matt
