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 new and comfortable air has taken hold of New England and will remain with us through at least the first half of the upcoming weekend - as a large area of high pressure brings wonderful weather to the Northeastern quarter of the nation!
The transition was a bit of a bumpy one Thursday with the areas of rain, but that feed of tropical moisture has been shunted south and east across the Atlantic Ocean, and while a patch of clouds lingered in Northern New England early Friday morning, it was breaking up as it moved south, and mostly sunny skies will prevail through our Friday. This sunshine comes courtesy of dry air found both aloft and at the surface, where dewpoint temperatures - the measure of the amount of moisture in the air - have dropped into the comfortable range of 50-60 degrees, as an expansive areas of high pressure extends from the Midwestern United States all the way to the Eastern Seaboard! This large area of high pressure and fair weather will eventually break down and allow for moisture to return, but that process will be a gradual one which means we can bank on another wonderful day for Saturday - continued sunshine and a continued very pleasant feel to the air. With all of the sunshine, though, the ultraviolet index will be very high to extreme in many areas, so you may want to consider the sunscreen and shades!
By Sunday, the expansive fair weather cell starts to diminish, while an upper level storm sits over the Mid-Atlantic states and the counter-clockwise "cyclonic" flow around the storm will turn winds aloft from the south. This southerly steering flow will help to nudge tropical moisture back northward again, and the first installment of deeper moisture arrives early Sunday. The battle between our dry air still in place, and the new incoming humid air, is likely to produce a burst of showers in most of New England Sunday morning. A wave of low pressure is likely to develop with the leading edge of this new installment of tropical air, and that will add a few tricky caveats to the forecast. For example, winds on the east side of that wave of low pressure will be confined to the outer South Coastal waters, but may reach 45 knots in gusts, so mariners are likely to find churned seas southeast of New England Saturday night through Sunday. Another caveat is that the wind ahead of this wave of low pressure will turn northeast Saturday night into early Sunday, and while most areas will swing to a southerly wind as the low passes, thereby breaking out some sun and bringing warm and humid air back into New England with a chance of showers and thunder bubbling up during the afternoon, Cape Cod will be much more sluggish to see the wind shift and the influx of new air. The result may very well be a prolonged period of clouds, fog and perhaps a few lingering showers on Cape Cod into Sunday. Farther north, the clash between the old Canadian air and new tropical air is likely to spell plenty of clouds for most of Maine and the far North Country.
Though tropical air will continue streaming back into New England into Monday, a stronger cold front will move east out of the Great Lakes and this will mean numerous thunderstorms for New England on Monday by the way things are looking now, though behind the front would come a more enjoyable Tuesday.
Looking farther out into the future, a flow from south to north - tapping the tropics - is likely to re-establish later in the week. The problem we'll need to watch very carefully is that a tropical wave currently over the Central Atlantic will be steadily moving west, and if this should develop into a depression or storm, the pathway to New England may remain open toward the end of next week. Needless to say, I'll be keeping a close eye on this potential.
Have a wonderful weekend.
Matt
Matt's Technical Meteorological Discussion: Updated Friday, July 6 at 1:20 PM
Straight-foreward fcst thru Sat - some valley fog tonight as few spots will decouple with clear skies, light wind, dry air. Will use this opportunity to expand on tricky forecast issues, and in the short range the biggest fcst challenge is certainly the Sunday forecast. Terrible run-to-run consistency among not only the two primary American products of the NMM/GFS, but also problems in the foreign guidance. The Canadian Ensembles have come much farther north - by several hundred miles - in the northern edge of precip shield for Sun. Most consistent thus far has been the ECMWF, which has shown two consecutive runs - sad that it's our most consistent!
So, let's look beyond the run-to-run and model-to-model problems and view the bigger picture, which puts the steady tropical feed well southeast of NewEng for the next 48 hours. Of course, the problem for us as meteorologists and weather-enthusiasts is the upper level low that dips over the Southern Mid-Atlantic Sat and exerts its counter-clockwise flow to usher the tropical feed northward later in the weekend. The problem here is that the upper level and lower levels flows aren't matching up with a surface anticyclone doing its best to hold dry air in NewEng while tropical air re-orients aloft. There are a few tidbits that can be garnered from the guidance, even if the details are muddled, and one of these tidbits can actually be seen in a field I generally hate to look at - the QPF field! I mention that I hate to look at this...in reality I should say I look at it last, as the synoptics drive precip and are most important, but certainly trends can be monitored in QPF forecasts, and the field can serve as guidance. In this case, there is great agreement that the main band of precip stays southeast of NewEng, under the primary tropical feed.
This isn't the end of the story, though, as the developing southerly flow will carry the tropical wave currently located along the Eastern Florida coastline northward. This wave is progged to develop a strong 45-55 kt 850 mb wind on the east side of the circulation, and this will churn seas up on the outer southeastern coastal waters of NewEng Sat Ngt and Sun. But, while this wave is coming out of tropical air, it's different from the wave of last week that brought tropical storm force gusts all the way up the coast - this one keeps its wind on the east side of the circulation, largely as a result of gradient flow between the high pressure center and the surface wave of low pressure, and given that the low-level support shears out as the system outruns the tropical zone and overruns the baroclinic zone, we're unlikely to find a strong core of wind holding together with this system as it moves into NewEng - at least by the way I see things right now. Nonetheless, a rather substantial shot of positive Theta-E advection will occur from 850 mb upward through 700 and 500 mb, and this is indicative of a non-surface based packet of moisture riding north of what essentially becomes a tropical warm front, as strengthening southerly flow is likely to develop behind the wave, which takes on a similar structure to a glorified wave on a warm front. This should bring a shot of showers or rain early Sun AM to most of NewEng as it collides with the drier airmass, tho from that point forward the forecasting gets tricky. The surface low track is still somewhat in question, but it does appear as though a northeast flow at the surface will precede the low center for most of Eastern NewEng Sat Ngt, then the east and northeast flow will persist north and northeast of the wave center - namely across much of Maine. It's going to be tough to get warm air into most of Maine except perhaps far Southern Maine if this is the scenario that plays out, and in fact, most of the far North Country will stay under the battle zone of southerly flow transporting warm and humid air, and the old Canadian air slow to move out given rather high surface pressures. This is likely to mean lingering Sunday clouds in the Northern Mountains of VT, NH and, as mentioned, most of ME. Farther south into the remainder of NewEng, moisture transport will bring 60s dewpoints back into the region with breaks of sun assoc with mid-level dry slot boosting temps into the 80s and allowing tstorms to bubble up. Somewhat of a wild card in all of this is Cape Cod, as the northerly flow may be slow to abate, and once it does we're warm and moist advecting into a lingering cool airmass and ocean flow which means the Cape is at high risk to be stuck under low clouds and fog.
Farther out...strong front progged for Monday is likely to bring plenty of storms for most of NewEng as the prefrontal trough ahead of it intersects with increased moisture in the lower and middle levels. Actual fropa probable to occur Mon Ngt or early Tue and much drier air spills in behind it.
For the middle and end of next week, we turn our attention to the tropics. Not just to a tropical flow this time, but to the Tropical Atlantic, and we'll see what's brewing by early next week. At this point, however, the Ensemble members have been giving signs since Monday of the tropical wave over the Central Atlantic (currently at 30 W, 7 N as of this writing) having the potential to organize as it passes the Leeward Islands. This wave certainly was intense as it emerged off the western coast of Africa, and has maintained some organization though convection has been sparse. The GFS is taking this system into Florida around the middle of next week which seems unlikely given the persistent weakness in the 500 mb ridge that will still be present along the Eastern Seaboard. I should note that while the Ensembles have been consistent with this since the beginning of the week, the operational models have been slower to catch on, but all except the UKMET have now grasped onto this wave and its likely organization (albeit slow) over the next 72-84 hours. Given the forecasted 500 mb flow, and the strong ridge over the Western Atlantic, the most likely path for this disturbance would be similar to the 12Z GFS (for reference) through early in the week, but then recurving somewhere around or just east of the East Coast of Florida. This certainly puts New England and the remainder of the Eastern Seaboard on guard, though at this early juncture it would appear as though upper level flow is too westerly to allow this system as far north as New England. Still, the northern stream will be rather fast and therefore timing of shortwaves cannot be relied upon that far out, so a change in the timing of the shortwave would certainly raise the risk for NewEng, so this will be one worth paying close attention to for the next several days.
Enjoy your weekend - let's keep an eye out for Beryl over the next 4 days!
Matt
