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:
First and foremost, the National Oceanic and Atmospheric Administration (NOAA) has issued their 2007 Hurricane Forecast for the Atlantic tropical season. The forecast, like its predecessor out of Colorado State University, issued by Dr. William Gray earlier this spring, predicts above normal tropical storm activity this year. Of course, that was the forecast last year as well, but those of you who were reading this discussion last year might remember the investigation into sea surface temperatures in the Pacific in the early stages of an El Nino event that ended up strong enough to have a significant impact on tropical development. Will this year's forecast be closer to reality? Chances are good with either a neutral or La Nina pattern, and favorable upper level winds, that this year's activity will indeed rank above normal when contrasted to the historical average. Next week, after Memorial Day, I'll bring you early season preparation tips with a different theme each day here in the blog. In the meantime, you can click here to open a new window with the National Weather Service hurricane forecast.
Of course, the weather right here at home has been quiet and will continue to be tranquil and pleasant through just about the entirety of the week, with the biggest change in sight a substantial warm-up slated for Thursday and Friday.
There was no sign of impending warmth early Tuesday morning, when some of the colder locales in New England dropped to the upper 20s, and frost was reported in many sheltered locales of interior Central and Northern New England. One of my weather observers, Bob Conway, even reported temperatures in the 20s in the cranberry bogs of Carver, Massachusetts! In some communities, especially Southwest New Hampshire, North Central Massachusetts, and Southeastern Massachusetts to the Islands, it was a foggy start, with near zero visibility on Vineyard Sound early Tuesday, but abundant dry air ensured this fog was quickly evaporated. Thereafter, temperatures began responding rapidly to sunshine, and that will continue to be the case through Tuesday afternoon. With a very dry Canadian airmass building overhead, the atmosphere will be well "mixed," implying that air from several thousand feet above the ground will descend to the surface, and vice-versa. A pattern like this supports quickly warming temperatures, with the notable exception being along New England coastlines. As the center of high pressure and fair weather drifts directly over New England, winds are quite light near the center, and therefore the difference in temperature between warm land and cool ocean can easily establish a sea breeze circulation, keeping coastal communities in the 60s while the interior climbs to around 70. The good news is that fire danger remains low in most spots to moderate in a few, largely because of the combination of weekend rain with new, moist vegetation that's been blooming in the past several days. Of course, this also means the pollen count will continue to rise, and allergy sufferers will have it rough as the week progresses.
Though Tuesday night will be cool with only a few high altitude clouds and light wind, temperatures will not bottom out quite as chilly as they did Monday night, largely owing to a milder start to the night, and some milder air blowing in at about five thousand feet in elevation. Still, valleys of Northern and Central New England may see a scattered frost, keeping in mind what I discussed here yesterday, that air temperatures DO NOT need to drop below freezing for frost to form. This is a bit of a confusing concept for some, but the bottom line is this: the air warms and cools in response to the ground. That is, when the sun comes up at the beginning of the day, its rays don't warm the air directly, but instead warm the ground, which in turn warms the land. At night, the same phenomenon occurs in reverse...that is, the ground cools quickly with the loss of sunshine, while the air remains a bit warmer. The coldest part of the atmosphere, therefore, comes immediately adjacent to the ground, in a thin layer only a few millimeters thick, known as the "laminar layer." This ultra-thin layer of air is found around all objects, including our own bodies, and cools much quicker than the rest of the air, because it's closest to the rapidly cooling ground. The result can be for temperatures in this laminar layer to fall below freezing, even though measured air temperatures can still be in the middle and even upper 30s, resulting in frost though our thermometer reads warmer than 32 degrees.
Wednesday will be quite similar to Tuesday, with the center of high pressure and fair weather only slowly building southeast of New England, feeding air off the ocean into Eastern New England, keeping communities within about 30-40 miles of the coastline a bit cooler than we'd otherwise be as a result of the ocean-cooled air. Farther inland through Central and Western New England, though, temperatures will rise into the middle 70s as winds swing around to blow lightly from the south, indicating the beginning phase of an airmass change that will mark the onset of warmth that's been building across the Ohio Valley points south and west.
By Thursday and Friday, as high pressure continues to drift southeast and the clockwise flow of wind around it brings a deepening and strengthening west and southwest flow of air, the warmth to our west will be carried from the nation's midsection into the Northeast. The result will be yet another dry but much warmer Thursday across New England, before a strong jet stream disturbance carrying a cold front at the surface makes its way into New England late Friday, after temperatures near 90 in some spots, touching off late day and evening thunderstorms, some of which may be strong. I expect this cold front to bring in a dry and pleasant airmass on Saturday, though summer air won't be beaten down very far to our south. In fact, the rebound of warmth and moisture on Sunday may bring showers back to the forecast. Timing of this return of warmth will be critical not only to the timing and intensity of any showers Sunday, but also as to whether New England can burst back into warm and summery air on Memorial Day itself, with increased humidity and scattered showers and thunder. Though this is the way I see it playing out for now, there's plenty of time for things to change, and that timing will be especially important. But I can tell you that consistent signals have favored strong Northeast U.S. thunderstorms Friday, and a decent Saturday for quite some time.
Technical Discussion: None expected today. Will likely put one out Wednesday.
Have a wonderful Tuesday!
Matt
