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:
A few notes before today's discussion:
First, the following item just crossed the news wires as breaking news from the Associated Press, and I'm sure will make headlines in many forums, if it's accompanied with action:
URGENT Bush calls on 15 countries to set global emission goal by 2008 Eds: Moving on general news and financial services. WASHINGTON (AP) - President Bush on Thursday urged 15 major nations to agree on a global emissions goal for greenhouse gases and to reach a consensus by next year. With the United States often accused of dragging its feet on combatting climate change, Bush called for a meeting this fall of 15 countries identified as major emitters of greenhouse gases. This list would include the United States, China, India and major European countries. (Copyright 2007 by The Associated Press. All Rights
Reserved.)
Also, have you seen the new feature on Google Earth? Amazing stuff, as you can now actually see the view from locations in certain cities, right down to the street level! You click on an address and can get the "street view" and pan across the horizon, seeing buildings and other features at that location. Though no New England cities are featured cities yet, cities like Denver and The Big Apple are, so click here to check it out...and when the map loads, just click the "StreetView" tab on the upper right side of the map to see available cities!
OK, enough extraneous stuff for today - time to focus on the weather, which brings a big difference between communities from western to eastern New England today. The anticipated "backdoor cold front" moved through most of New England Wednesday night and Thursday morning. Remember that we call this type of front "backdoor" because, unlike most cold fronts that push into New England from the north or west, these come in from the northeast or east. The reason for this is usually when an area of high pressure moves across Quebec, carrying cool Canadian air and ushering that air southward in the clockwise flow of wind that pushes a northeast or east wind into New England. This phenomenon played out down the Maine coastline and into Eastern Massachusetts Wednesday night, and the wind shift continued to move west Thursday morning. To the north and east of this front, the cool Canadian air will hold high temperatures in the 60s to around 70 degrees, with a band of clouds along and just on the cool side of the frontal boundary that will persist through most of Thursday, dropping scattered showers as energetic disturbances ride through the atmosphere aloft. Those who are far enough north, especially in Northern Maine, will be so far into the cool and dry Canadian air that sunshine will actually warm these spots more than those farther south who are under mostly cloudy skies. Far enough south and west, through Connecticut and Western Massachusetts, enough warm air will linger for temperatures to rise into the 80s, at least from Western Connecticut through the Berkshires where the wind is unlikely to swing around to the northeast. From the Pioneer Valley through the Connecticut River Valley, temperatures will depend largely on wind direction, which right now is blowing from the northeast and won't allow for such warm temperatures unless it shifts by the end of the day. You can, of course, monitor surface observations through the links at left, and radar imagery through the links at right.
With New England straddling the boundary between cool Canadian air and deeper summer warmth streaming up the Eastern Seaboard, the fast corridor of winds aloft, known as the jet stream, that steer our storms and flow swiftly along the border of cool and warm air will be positioned overhead. Carried by this corridor of jet stream winds, one of these disturbances brought rain to Northern Maine yesterday, and another brought showers and downpours from Vermont southeast across New Hampshire, Southern Maine and Northern and Eastern Massachusetts early Thursday. The next in line will drop southeast out of Ontario Thursday afternoon, interacting with the warm air just south of our stalled front to create scattered showers and thunderstorms in the warm summer air of New York State into Western Connecticut and Western Massachusetts, and a few of these storms may pack some damaging wind bursts.
One persistent feature on the weather map is another area of high pressure to our south, positioned off the Carolina coastline. The clockwise flow of air around this center of high pressure favors a southwest wind into New England, contrasted to the northerly flow of the Canadian fair weather cell that's been exerting its influence on us Thursday. As the Canadian high pressure center weakens and retreats northward, a south and southwest wind will return through New England as soon as Thursday night, carrying increasing warmth and moisture northeast. This increase in moisture will result in thickening fog along the Maine coastline, which could be quite dense by Friday morning, and will serve to hold temperatures in the 50s for the remainder of New England with scattered showers amidst a northeast migrating band of clouds that will mark the return of summer warmth.
Clouds and areas of fog will begin our Friday, but the establishment of warm air to New England will also bring a return of sunshine to most areas by mid-morning, with the most glaring exception to be found in Central and Eastern Maine, where the cool Canadian air will be quite stubborn and the result will be a steady rain for most of the morning and early afternoon as temperatures hover around 60. Farther south and west, though, the effects of sunshine and a southwest wind in concert with the return of summer air will boost temperatures into the 80s Friday afternoon, with dewpoint temperatures - the amount of moisture in the air - climbing into the 60s and resulting in a sticky, humid feel for most of New England. The warm and sticky air will help to fire thunderstorms Friday afternoon as the active jet stream thousands of feet aloft send another disturbance careening overhead.
After perhaps a few additional showers overnight Friday night in especially Central and Northern New England with a stronger surge of warm air, deeper warmth should continue its return on Saturday with a blend of sun and clouds before another moderate strength upper level disturbance would regenerate showers, thunder and pockets of rain late Saturday through Saturday night. Feeding off the clash of northern cool and southern warmth, and with a bit of increasing moisture pumping northward from the Gulf of Mexico, rains may fall quite heavily during any of these downpours. This disturbance and its associated moisture should be transient enough to allow morning rains early Sunday to give way to breaks of sun before scattered showers and thunder crop up in the afternoon and evening. Once again, the Sunday weather scene may be muddied a bit by the same phenomenon observed on Thursday - a backdoor cool front seeping cool air into New England, though perhaps less pervasive than its predecessor, carrying coolest air across Maine and New Hampshire where Sunday highs may be in the 60s, but keeping remaining areas in the 70s under at least some increase in cloud cover. Overall, therefore, I'm not expecting a washout of a weekend, and I'm actually quite hopeful that, provided folks plan around the raindrops, a decent amount of fun and work can both be accomplished outside this weekend. By early next week, a steady supply of moisture would still be available to New England out of the Gulf of Mexico, and the atmospheric pattern is conducive for soaking rains, but a determining factor will be exactly where that abundant moisture is directed, and whether it's focused over us early next week.
Part of the uncertainty in that scenario is that the moisture will be largely a product of a tropical wave located just west of the western tip of Cuba as of this writing. That wave has been generating pulsing thunderstorms the past few days, and this moisture has begun organizing, streaming north into the Eastern Gulf of Mexico and soon to take aim on the Eastern Gulf Coast. Though it remains to be seen whether this tropical wave can organize quickly enough to be classified as a tropical system, it does bear watching, and should produce gusty winds for the Eastern Gulf Coast, regardless, as it interacts with the large high pressure cell off the Carolinas, and the difference in barometric pressure allows a corridor of strong wind to develop over Florida. The copious amount of moisture may be too much of what the doctor ordered for the extreme Southeastern United States, as the severe drought conditions and raging wildfires require rainfall, but several inches in 24 hours would be too much, too fast, and flooding is a potential. That same moisture is what I'll be watching for right here at home early next week, to see how it will play out as it becomes caught in the deep southerly wind flow pointing up the Eastern Seaboard.
Here's to a great Thursday.
Matt
Matt's Technical Meteorological Discussion: Updated Friday, May 15 at 2:25 PM
It's been awhile since I've pounded out a techie discussion - thanks for checking back in. Lots of public appearances the last few weeks, which is always very flattering (and a good thing, for sure!) but limits the amount of time I have for these technical discussions, which are usually composed after my last show of the day.
The frontal boundary over New England will continue to bring headaches for the next few days, and today is no exception. At issue here is just how deep the layer of surface cool air is that's been carried southwest across New England - clearly we've had a cool day for most of Northern and Eastern MA points northeast, but winds have been coming back around to south and south-southeast in Connecticut and this trend is working up the CT River Valley twd the Pioneer valley. Tds are low but sfc backing of the wind means we're looking at a situation that will favor localized high wind bursts in convection that fires with the interaction of vort max aloft and sfc frontal boundary. Meanwhile, gorgeous dry air making for splendidly pleasant sunshine in Central/Nrn ME. Those areas enjoying the taste of invigorating spring air, however, will see the gloomiest conditions over the coming days.
The shift toward southerly winds thru CT is just a precursor of what's to come for the remainder of New England overnight Thu Ngt, as the influence of the Ern Canada high breaks down. Warm and moist sfc advection will breed fog and low clouds thru most of ME, with pockets of fog farther south, and showers with gradual but consistent upglide over isentropes in especially Central NewEng. Tho many areas will be mostly cloudy thru the night, Southern NewEng will make the quickest transition to warmth and therefore may see enuf breaks to enjoy the "not so blue" moon (see link at top of General Weather Summary for that), tho the remainder of NewEng will likely remain shrouded in clouds until some mixing can break them up Fri AM. Thereafter, most areas are likely to break into sun and this means a quick transition back into the summer airmass, tho cool air will hold on in Ern ME where pressures are slow to fall and therefore clouds and periods of rain will be likely for most of the day in these areas with shortwaves traversing in the jet stream flow aloft. Expecting climbing temps and dewpoints into the 60s to breed over 1000 J/Kg of CAPE, and with another of several weak vorts progged to move thru later Fri, expect convective initiation. Heavy rain will be likely with most of the storms, tho ambient wind flow will be fast enuf to preclude flash flooding, tho the combination of H85 to H5 winds of 25-35 kts and a decent dry punch of air from H7 up, along with a wind profile that will veer with height, will favor damaging winds in convection, and this threat will be present for almost all of NewEng, but especially for Central NewEng, where wind fields are most impressive.
Convection will wane Fri Ngt, but will take awhile to do so nearest to the H85 theta-e gradient over Wrn ME, where storms will get a bit of extra feed from the positive theta-e advection. Next vort max on Sat should also result in scattered convection, and tho wind fields will be lighter in Srn NewEng, still a decent 35+ kt midlvl jet over Central and Nrn NewEng, where severe threat would be highest. With deep moisture, expecting heavy downpours most areas with the storms.
Though I believe Sunday will bring a backdoor front into NewEng, there are a few reasons why I don't expect it to be as significant as the one we've experienced today - first, the bubble high over Eastern Quebec is 1018 as compared to 1023 mb. Second, the low to our west will be 1003 instead of 1006 mb. Each of those factors favors a weaker backdoor. Additionally, there's a large trough, not a protruding ridge, over the Great Lakes, and this won't favor such strong NW flow aloft over NewEng, meaning less cold air penetration. Therefore, I expect cooling thru ME and perhaps Ern NH, but still mild conditions elsewhere.
Finally, attention will turn to the Eastern Gulf. I've explained the setup in the General Wx Summary, but here are a few more thoughts on the area of disturbed weather I've been watching off the Western tip of Cuba for the last few days: A broad circulation has been visible for a few days on satellite imagery and continues to be evident just east of the Yucatan. QuikScat imagery does not indicate a closed surface circulation tho pressures are lowering, so while the majority of the circulation is probably still midlvl, a sfc center is bound to develop imminently. This circulation is over water that is 27 C (81 F) and therefore just warm enough for TC generation. The question over the coming days regarding tropical or non-tropical status will probably revolve not around whether the system is warm core (it's most likely to be) but exactly what the impetus for wind will be. That is, model indications are for strongest wind on the east and northeast side of the circulation, and initial indications were that this is partly or perhaps mostly in response to pressure gradient forcing on the SE side of the sfc ridge centered off the Carolina coastline. Latest NMM, however, tries to develop the low as its own entity, so this is one to keep watching, but the results of gusty wind and copious rainfall will be the same for the far Eastern Gulf coast this weekend. The problem is too much of a good thing on the parched, scorched landscape, that may see all of its beneficial rain in 24 hours - a bit too much, too fast, and flooding may result. Nonetheless, I'm sure it will help those dry areas. Here, we'll need to watch that moisture, as while I think we may get some fringe input as soon as Sat eve and night (enhancing our convective rainfall rates) the slug of moisture would arrive early next week, and I have doubts about the GFS shooting this southeast of us given the developing meridional flow and the opportunity for northern stream interaction and perhaps inches of rain early next week if the interaction lines up right.
Enjoy!
Matt
