Welcome to the weather blog! While the web address has changed, the blog will still be the same Monday through Friday discussion - with some improvements! Over the course of the next few weeks and months, you'll find me experimenting and adding new features. Maps, pictures, and other multimedia are enhancements I'm hoping to be able to make as I learn more about how to maximize the new site. Format will be similar to the old version - you'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net. This blog is for you, so I hope you enjoy it! -Matt Noyes
For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net
Matt's Weather Summary: I almost never offer my personal thoughts on anything in these posts, but I think it's necessary here regarding the Taunton Dam situation: The situation with the Whittenton Dam in Taunton should be monitored through NECN broadcasts or by monitoring the National Weather Service statements. For those of you with concerns and interests in the Taunton area, I can only tell you that if you've evacuated or know someone who has, you've done the right thing. I try to put myself in the shoes of residents who have been evacuated, and I'm sure for many of you this has been a confusing few days - and the confusion continues. Yesterday morning we received official government reports that dam failure seemed imminent, then we were told in a midday press conference that "imminent" was never the case. Yesterday afternoon we saw a dam engineer telling us the excessive vibration was very concerning, and today an engineer from the very same company told us there's been no excessive vibration and he doesn't know why that term was used. We saw one official this morning telling us the reason for the problem is that the rains causing this flooding caught us by surprise as evidenced by the flooding in New Hampshire and Rhode Island. Make no mistake about it - heavy rains were forecasted and no surprise. Flood watches were up for all of New England for several days, heavy rains were forecasted, media coverage was intense if not excessive leading up to the rain, and dam breaks were part of the concern from as much as one week in advance of the heavy rain. Overall, this was probably among the best-advertised flooding events we've ever had in New England history, and just because flooding occurs doesn't mean it was a surprise. But all of this said, the bottom line is we have to cut through the politics involved here and understand that there's great stress on both dams in Taunton right now, and we are in a wait-and-see mode. Regardless of their conflicting reports, I have no questions that the dam engineers are competent in their inspections, and officials will make the best decision possible. We must cut through the political speech - and it's my hope that I can assist you in this by assuring you that if you've followed evacuation orders, you've done the right thing. We should continue to follow these orders until engineers deem the dam safe - if the worst case scenario should occur, a 6 foot flood wave would make it from the dam to downtown in 60 seconds to two minutes and you would not have time to evacuate, so the need is to be safe and smart. This is costing a lot of us a lot of money in Taunton, but it's necessary at this point. The bottom line of why this happened is no surprise and has happened time and again in the past: the dam is old and not at maximum strength, the rains came down hard, and this is the result. But the bottom line is also that we have to trust that our officials would not put lives in danger, and follow their orders and suggestions as given.
For all folks concerned about obtaining flooding insurance: Please reference www.FloodSmart.gov. This is a government site that has existed for a few years with links to information on obtaining flood insurance.
NOW ONTO THE WEATHER...The next in our series of fast-moving and energetic disturbances moving across New England is racing into the six state region Wednesday morning. For Southern New England, the air is relatively dry and no showers are expected with this disturbance, though morning sunshine will play hide and seek by afternoon with increasing clouds, and breezes will increase from the southwest. As you can see in the forecast at left, the combination of a southwest wind and some limited sunshine will warm much of Southern New England back around or over 60 degrees. In Northern New England, we'll be closer to the energetic jet stream disturbance and its associated surface low pressure center, and this means we'll find showers and periods of rain developing Wednesday afternoon and lasting through Wednesday night with a breezy southwest wind turning to the northwest and draining cooler air into the region. While Southern New England stays dry through Wednesday night (except Berkshire County where a few afternoon and evening showers may pop up), Northern New England finds this cooler air changing rain showers over to snow showers early Thursday morning, and many of us in Northern VT, NH and ME will find snow showers Thursday morning. Now worries - no accumulation is expected except perhaps a brief coating on grassy surfaces.
During the day Thursday, winds will be gusty from the northwest as New England is squeezed between the departing area of low pressure and an incoming bubble of fair weather, or high pressure. These northwest winds will carry down drier air from Canada, and snow showers should dry up in Northern New England while Southern New England sees another day of dry and partly sunny weather.
Our protective bubble of high pressure keeps encroaching rains south and west of New England on Friday, as well. These incoming rains will be the product of the very same bundle of atmospheric energy that brought flooding rains and mudslides to Southern California and the Southwestern US the last few days. As this energetic upper level storm center moves slowly into the Ohio Valley, it will push increasing moisture toward New England, and high altitude clouds will increase Friday afternoon and evening.
By Saturday, as high pressure pulls away from New England, clouds will continue to thicken through the day with a push of warm and moist air pulsing northeast ahead of the aforementioned upper level storm. It appears as though rains will spread into New England by Saturday evening, with periodic rain Saturday evening and night. These rains should not be flooding rains - more likely a widespread light to at times moderate rain.
Sunday and Monday's weather are a bit trickier. Here's why: Hurricane Wilma, as of this writing, is moving slowly toward the west-northwest south of Cuba. She went through a period of rapid intensification last night, and went from a tropical storm to a major Category 5 hurricane over 24 hours. This happened thanks to the warm ocean waters she was sitting over, as well as winds aloft that were perfect for intensification. In fact, a hurricane hunter aircraft penetrated the storm's tiny 2 mile wide eye Wednesday morning, and measured a pressure of 882 millibars - making Wilma the strongest hurricane ever to exist in the Atlantic Basin since record-keeping began in the 1800's. It will be nearly impossible for Wilma to maintain this record intensity over her trek north and northeast the next few days, but she certainly may still be a major and damaging hurricane when she makes landfall. At this point, it appears as though the old California storm moving through the nation will turn the winds such that Wilma will blow into the Western Florida coastline - passing over or near Lake Okeechobee Saturday night. By later this weekend, the questions for our own forecast revolve around exactly how Wilma interacts with the upper level storm moving toward us from the west. There are strong signals that at least part if not all of Wilma will be drawn northwestward toward this upper level storm, and this would bring the possibility of another shot of flooding rain and perhaps strong winds to New England sometime late Sunday or more likely early next week. But at this point, it's a potential we have to acknowledge but we also have to understand this all will depend on the timing of each storm center. Time will be needed to see how the atmosphere evolves in this regard.
Technical Discussion: Out By Early Afternoon.
Have a great Hump Day.
Matt
Matt's Technical Meteorological Discussion: Updated Wednesday, October 19 at 2:00 PM
Pacific moisture tap really not linking up on the south side of this energetic vort cutting across NewEng today, so Srn NewEng should stay dry excepting upslope assisted lift of the Berkshires, while Nrn VT/NH/ME sees rain moving in from W to E. Amounts should be fairly light in most spots though duration of precip extends thru Wed Ngt and into Thu AM as winds shift NW and upslope flow sets in across far north. Mountainous terrain of Nrn VT/NH and NW ME should go from rain to snow showers late Wed Ngt and persist thru Thu AM as cold shot of Canadian air teams with upslope flow for adiabatic cooling. Precip amounts are very light but a coating isn't impossible on grassy surfaces.
Thursday as we squeeze between departing low and Canadian high building SE across Great Lakes, and as baroclinic zone tightens while pushing over and south of NewEng with low-level frontogenesis (not necessarily formation so much as strengthening of the low level thermal boundary) winds will gust over 20 mph from the northwest and air should be cooler than MOS even given downsloping flow. Low to mid 50's should cut it most areas, but obviously cooler in higher terrain and esp upslope areas of the north.
Bubble of high pressure building SE across Great Lakes protects NewEng Thu and Fri. Widespread lows in the 30's Thu night as high builds in. Cirrus clouds to increase later Fri as we find ourselves north of precip shield sliding S of New Eng and thru the Mid-Atl where tight baroclinic zone will be located and isentropic lift begins in warm advection ahead of former California upper low over the OH Valley. 12Z NAM has jumped all over precip into Southern NewEng during Saturday - to me it looks like it's too strong too fast given the forecasted tight baroclinic zone to our south and the strongest warm advection being southwest of NewEng to start the day. Additionally, the 500 mb prog doesn't support the seemingly too far east low level circulation. Probably ends up being a day of thickening clouds with rain developing from SW to NE late in the day and toward eve as warm advection and low level speed convergence nudge into NewEng. Not sold on high amounts for Sat as deep warm and moist advection should remain to our west. Saturday night should bring a decent shot of precip as the occlusion and possibly even a weak triple point from the primary low over the Great Lakes winds northeast and shifts the lift into NewEng. Difficult to say at this point how much we're talking about, but amounts of .5-1.0" are my thinking right now.
From Sunday morning through Monday, a tremendously difficult forecast pattern appears - not necessarily because there are a million different solutions (really there are a relatively low number of possible outcomes) but because of how high the stakes are. For instance...
Worst case scenario: After a stalling occluded front which serves as a pathway for Atlantic moisture and a convergence zone for lift in the low levels, a major storm strike on New England of a hurricane in the process of intense extratropical transition, being pulled westward in retrogression as it's pulled into the tremendous upper level low over the Great Lakes, discussed here in Monday's discussion. A storm such as this would be taking one of the worst trajectories possible into NewEng - coming in from the southeast as it wraps into the upper low - and would deliver a blow of tremendously heavy rain with deep Atlantic inflow and at least Cat 1 winds with likely gusts to Cat 2 as it accelerates and pulls in.
Best case scenario: Wilma goes out to our south, occlusion pivots through quickly and Saturday night's rain is heavier than what I mentioned a few paragraphs ago, but the occlusion goes north and heaviest rain falls along or north of the Canadian border while Wilma skirts out.
The forecasted synoptic situation for the period hasn't changed much from Monday's thinking, which isn't necessarily a good thing for NewEng - that is, the upper level low moving thru the Rockies/Central Plains currently will slow and begin to break apart as it enters the OH Valley, with pieces launching across the Mid-Atlantic coastline with a band of rain along the well defined low-level baroclinic zone. Part of the reason for the pieces left behind by this system meandering in the OH valley is that they become lodged under a building shortwave ridging structure that sets up in advance of a tremendous shot of Canadian energy dropping SSE directly from the Arctic circle. At the same time, we find evidence for the theory of holding rain off on Saturday in the strongly confluent flow at 500 mb that sets up over Eastern NY Friday night and Eastern Maine by Saturday night. As this confluent flow pulls away, the thermal zone to our south is allowed to lift northeast and puts us into a rain shield as already mentioned for Saturday night. Also on Saturday night, a lobe of vorticity pivoting around the belly of the old California upper low will be moving east thru the SE US with thunderstorms and Wilma concentrated rainband, while backing winds and helping to keep Wilma moving across Florida and off the SE US coast. It's then that the Canadian vort max and old upper low combine forces and really deepen the new upper low. In fact, from Saturday night to Sunday night, Ensemble means agree on deepening the negative height anomaly from a -200 gpm to a -300 gpm - not only a remarkable negative anomaly for this time of the year, but also a remarkable rate of deepening, which coincides with the anomalously high heights developing north of the upper low, in Canada, and thereby allowing warm advection into the system from the dynamically unstable ridge to the north. One should note, if for nothing else but posterity, that this dynamically unstable ridge was evident during formation of the Perfect Storm of late October 1991 in the merger of Hurricane Grace. The same disparity in static stability existed across the ridge/trof setup, but the obvious differences were two-fold: 1) The Perfect Storm obviously was much farther east, which plays with things like storm strength, etc., upon time of merger, and 2) The trajectory at which Grace was absorbed, resulting in a retrograding upper low that brought a long-duration blow to NewEng as the storm backed into the coastline. This merger would be occurring farther west and Wilma, should she be absorbed, is going to be riding through New England before being pulled into the upper low entirely. That means the potential for less duration, but higher intensity over a larger area. Otherwise, however, the 500 mb maps for an analysis of Oct. 29-31 '91 and the forecasted map of 500 mb heights for Sunday Night/Monday scenario looks eerily similar with regard to the unstable ridge that eventually completely bridges across the top of a rapidly deepening upper low. Synoptically, what this deepening low would act as an atmospheric sink, so to speak, pulling nearby disturbances toward the center. The question quite obviously with regard to this part of the scheme is whether it can effectively include Wilma in it's sink, or if Wilma can ride out just barely to the southeast of the periphery of the upper low. But of concern on a separate but equally important level is the strengthening of winds that will occur in the jet stream flow along the Eastern Seaboard as the meridional flow sets up. And, as anomalously high heights build across Canada, the easterly component to the upper flow that will establish to the east and north of the upper circulation. The reason for concern with these is obvious when one dwells for a moment - rapid meridional flow would mean rapid acceleration of Wilma, and a more easterly component introduces the potential for a north-northwest moving storm upon impact.
With regard to answering the question of whether Wilma becomes caught in the circulation of the upper level low or not, I truly believe - and followed this in my broadcasts - that the most responsible answer is we just don't know. It's quite interesting to see that even the models progging Wilma to keep trucking SE of NewEng have been doing two important things: 1) Wrapping additional weaker vorts ahead of her NW into the circulation, and 2) Trending farther west with Wilma with each run. These are both causes for concern, obviously. But equally important parameters are the 500 mb height field from the Ensembles - which paint confluent flow SE of Nova Scotia. The Atlantic ridge is forecasted to pulse a bit by Monday, but this may be in response to the influx of latent heat release on the east side of Wilma, so the synoptic pattern may favor taking Wilma SE of NewEng and toward the confluent flow. If this confluence shifts farther E in further runs, this will be a cause for concern. But even if the actual tropical center of Wilma should move SE of NewEng, a piece of Wilma saturated with tropical moisture would still be likely to ride west or northwest up the occluded front that will have moved into NewEng Sat Ngt and likely will stay in place under the weakness in the height field between our two interacting systems. But again...I stress that the only real answer on whether Wilma gets sucked it or spit out is "we have to wait and see."
And we will.
Later!
Matt