Summary: The surface low pressure system that was Sandy is now located somewhere over the eastern Great Lakes and is starting to lift to the north into Canada. It has weakened markedly as it has moved directly under the cold trough in the atmosphere that helped intensify it and bring it onshore. As long as the surface low was to the east of the trough it could draw on the jet stream energy being generated by the trough. Now it has lost both of its energy sources, the jet stream and the warm ocean water. However, as it continues to weaken and move north we will continue to be influenced by the very large circulation of clouds and diminishing shower activity associated with it. Temperatures have dropped as the sub-tropical air has departed and the cold trough has drifted eastward. Although it will be mostly cloudy for several more days, through at least Friday and probably into Saturday, we should remain relatively dry with only a few widely scattered and generally light showers and sprinkles. The best chance for a shower appears to be late Thursday afternoon into Thursday evening. Temperatures will be cold enough aloft Thursday night and Friday that there could be some snow flakes, particularly over the elevated terrain. However, any snow that falls will not stick to the ground or accumulate. It will be seasonably cool, even a few degrees below average (can you believe it!) for the foreseeable future. As the surface low finally make a serious move out and high pressure from Canada starts to build in on Saturday, the pressure gradient will increase and it may become fairly breezy (NOT as windy as Monday). Hopefully, the high pressure system will get close enough for us to have a SUNNY day on Sunday.

Wednesday Night

Mostly cloudy (75-99% cloud cover). There is only the slight chance of a light shower or sprinkle. Probability of precipitation 20%

Temperatures will not drop much with the cloud cover with lows in the upper 30s.

South-southwesterly winds at 5-10 mph.

Thursday

Mostly cloudy. There is the chance of scattered showers late afternoon. Probability of precipitation 30%. Any rain that falls should total less than 0.05 inches.

High temperatures in the upper 40s in most areas, near 50 in South County and only low to mid 40s over the elevated terrain and hilltowns, depending on elevation.

South-southwesterly winds at 5-10 mph, becoming westerly in the afternoon.

Thursday Night

Remaining mostly cloudy. There is the chance of scattered showers early. Probability of precipitation 30%. Any rain that falls should total less than 0.05 inches.

Low temperatures will be similar to Wednesday night…upper 30s in most locations with mid 30s in some elevated locations.

Light westerly winds.

Friday

Still mostly cloudy . There is still the slight chance of a shower. Probability of precipitation 20%.

It will remain seasonably cool but may even be a few degrees cooler than Thursday. High temperatures in the mid 40s in Pittsfield and North Adams, upper 40s in Great Barrington and low 40s in elevated terrain and the hilltowns.

Northwest winds at 8-12 mph.

For the weekend….

Saturday should be mostly cloudy, becoming very breezy and cool. High temperatures generally in the mid 40s. Winds will increase to 15-20 mph with some higher gusts in the afternoon. It should start to clear Saturday night, and Sunday will likely be mostly sunny and seasonably cool with temperatures generally in the upper 40s.

I apologize, my power has been out all day so I will not be making a forecast today. I will resume tomorrow. Student forecasts begin this Friday, November 2 and will be posted every Monday, Wednesday and Friday until the end of the term (Friday, December 14).

A few notes about Sandy. Many records were broken including the lowest barometric pressure ever recorded in the continental U.S. at Atlantic City – 948 mb (28.01 inches). The BCC weather station, hundreds of miles from the storm center, which made landfall near Atlantic City, recorded a barometric pressure of 981 mb (28.98 inches). The incredible pressure gradient was responsible for the incredible winds, which spread out over hundreds of miles. This is not typical of a tropical system and occurred because, as discussed previously, in addition to the localized dynamics associated with the tropical core of this system, the interaction with the jet stream was able to add to the overall energy of this storm and generate a much larger system. Wind gusts between 80 and 100 mph were recorded from the Delmarva Peninsula all the way to Boston, MA!! This truly was an unprecedented and historical cyclone. Associated with this large area of hurricane force winds there were record storm surges from the Long Island Sound to the southern New Jersey coast. The surge was particularly prominent in the NYC area due to the orientation of the coast relative to the wind direction and the fact that there were sources of water from the LI Sound and the Atlantic Ocean, all converging in that area. Locally, the BCC weather station recorded a maximum gust of 48 mph, the Pittsfield Airport recorded 58 mph, there was a gust at the Otis Reservoir of 61 mph and an unofficial gust in Hancock of 77 mph. Although there were power outages, we were definitely spared the worst because the trees had already lost their leaves. A few representative rainfall totals are BCC: 1.25 inches, Pittsfield airport: 1.28 inches, Great Barrington: 1.82 inches, and my house in Richmond: 1.52 inches. Rainfall totals of 5-10 inches were commonplace in parts of the Mid-Atlantic and there is flooding in many locations. Heavy wet snow has fallen, and is falling, in the mountains of western NC, VA and WV with up to 3 feet reported in WV.

Summary: I would like to say that I am surprised at all of the school closures, including BCC, for today, but I am not. I do understand why those responsible made this decision. However, as usual, the actual potential impacts for Berkshire County may have been lost in the tremendous amount of hype. Really, despite how dangerous this storm is for many areas, for us, it is just a very windy day. In fact, the really strong winds won’t occur until late this afternoon. Interestingly, to my eye, even the Weather Channel is doing a fairly responsible job of reporting the scientific facts surrounding this unusual and historic storm. However, the way the material is presented sometimes conveys a global sense of overwhelming catastrophe for the entire Northeast, even though the potential for real catastrophe is generally limited to the immediate coastal areas. For those coastal areas, anyone remaining behind is at risk of significant flooding impacts. Winds along the coast will also be MUCH higher than inland with widespread hurricane force gusts. In addition, 5-10 inches of rainfall in parts of PA, NJ, MD and DE will result in significant “rainfall” flooding away from the coast and heavy, wet snow is occurring, with 2 feet of snow expected in the mountains of West Virginia and western Virginia. Interestingly, what may get lost in the hype, and the usual perception by the population that this event was not as bad as predicted, is that lives will likely have been saved because we now have the technology to have predicted the track and intensity of this storm several days in advance. I think the sense that these storms are “over” predicted is somewhat a matter of perception due to the way the information is presented, not the actual facts that are presented. I think part of the problem is the level of excitement being conveyed by meteorologists (and I am probably guilty of this as well) because this storm is so unusual and interesting from a scientific standpoint. From a purely scientific standpoint, this storm has been incredibly well predicted by the computer models so far.

The latest advisory from the National Hurricane Center (NHC) has sustained winds at 90 mph and is moving northwest at 28 mph. The barometric pressure has fallen to 940 mb! Wind gusts in NYC have already reached 66 mph (JFK) with a barometric pressure of 28.84 inches (975 mb). This is an incredibly low pressure, particularly considering that the storm center is 100 miles southwest of NYC. Wind gusts of 80 mph have been recorded in Montauk, in eastern LI. Coastal flooding is already occurring. Storm surges are already over 5ft. in the NYC area and along the New Jersey coast. Conditions will continue to deteriorate until the storm makes landfall in about 4 hours.

Back to Berkshire County, really, this is just a very windy day for us. In particular, the strongest winds are not expected until late afternoon. That being said, the BCC weather station, as of 1:30 pm is recording wind gusts in the 30s. However, winds are stronger in the hilltowns to the east where power outages are already occurring (e.g. Savoy). Barometric pressure has already fallen to 29.24 inches (990 mb). The winds will be strongest from about 4-8pm when gusts will reach 50 mph in the lowest elevations to up to 75 mph in higher elevations. Rainfall will be heavy for a time late this afternoon into this evening but it still looks like we will only receive 1.50 to 2.00 inches by the time the significant rain ends by Tuesday around noon.

Monday Afternoon

Rain, heavy at times. Probability of precipitation 100%. Rainfall totals between 0.50 and 0.75 inches.

Temperatures steady in the mid 50s, with some upper 50s in South County and low 50s in the hilltowns.

Wind increasing to 25-40 mph with gusts from 50 mph to 70 mph (depending on elevation) late.

Monday Night

Rain, heavy at times in the evening. Rainfall will become more showery and lighter after midnight. Probability of precipitation 100%. Rainfall totals of 0.25 to 0.50 inches will fall, mostly before midnight.

Temperatures will hold steady or even rise a few degrees as somewhat tropical air moves in with the storm.

The high winds discussed for Monday afternoon will hold through the evening hours and then diminish to 20-30 mph by midnight. Winds will shift to the east after midnight and diminish to 15-25 mph by daybreak. Some stronger gusts of 40-50 mph are still likely in the late evening with gusts to 35 mph by daybreak.

Tuesday

Scattered rain showers likely in the morning. Showers will become isolated, and may even end during the afternoon. In fact, as mentioned yesterday, we could get into a wedge of drier air for a time and the sun may even poke through later in the afternoon. Probability of precipitation 80% in the morning, decreasing to 50% in the afternoon. Rainfall totals between 0.10 and 0.20 inches, mostly in the morning.

It will be mild, with high temperatures near 60 in Pittsfield and North Adams, low 60s in Great Barrington and high 50s in the elevated terrain and hilltowns.

Southeast winds at 15-25 mph in the morning diminishing to 10-20 mph later in the afternoon. There could be a few gusts in the 30s (mph) early.

Tuesday Night

Mostly cloudy with scattered rain showers likely, particularly after midnight. Probability of precipitation 70%. Rainfall totals 0.10 to 0.20 inches.

Low temperatures near 50 countywide.

Southeast winds shifting to south after midnight and diminishing to 5-15 mph.

Wednesday

A few showers are still likely but will be more scattered than previously. Probability of precipitation 50%. Rainfall totals generally less than 0.10 inches.

Temperatures will not rise much as the cooler air associated with the trough to our west starts to move in as the surface low begins lifting to the north out of our area. High temperatures will be in the low 50s in Pittsfield and North Adams, mid 50s in South County and near 50 in the elevated terrain and hilltowns.

South-southwesterly winds at 5-15 mph.

Summary: The forecast has not changed much since yesterday. It appears that Sandy will make landfall along the New Jersey coast near dinner time tomorrow. The models continue to generate a very low central pressure of around 950 mb. One note of concern that I have is that the models were only predicting a central pressure of around 960 mb for this afternoon but the latest National Hurricane Center (NHC) advisory indicates a central pressure of 951 mb! To reiterate, coastal regions are the major concern from this storm. In fact, evacuations of the NJ barrier islands and some low lying portions of Manhattan have begun. The storm surge models I have looked at have increased their estimates slightly, with a surge in the 9-12 foot range for portions of the NJ coast and near NYC. It still looks like the greatest surge will be near high tide so that water heights could be more than 12 feet above mean sea level. Fortunately, this is not something we need to worry about in Berkshire County.

Our forecast is similar to my discussion yesterday. The only change I would make is to increase wind speeds slightly given the recent strengthening of the storm. Flooding should not be a major concern with 1.50 to 2.00 inches of rainfall expected. However, there should be considerable wind damage with many limbs and even a few trees coming down. The damage will be limited somewhat because the trees have lost most of their leaves. Power outages are likely.

The worst of the wind should be during the late afternoon and evening on Monday. Winds will begin to diminish after midnight but will remain quite strong until Tuesday morning. Although still somewhat windy on Tuesday, the damaging winds will have ended. Most of the rainfall will occur Monday afternoon and night with only scattered showers after that.

Sunday Night

Overcast and becoming breezy. There is a good chance of a few scattered light rain showers towards daybreak. Probability of precipitation 50%. Any rainfall totals should be less than 0.05 inches.

Temperatures will not drop much and low temperatures will be in the upper 40s.

Northeast winds at 8-12 mph this evening, increasing to 10-20 mph after midnight and 15-25 mph by morning.

Monday

Scattered light rain showers likely in the morning. The rain will become steady and moderate at times during the early afternoon and heavy at times during the late afternoon. Probability of precipitation 60% early increasing to 100% during the afternoon. Rainfall totals between 0.50 and 1.00 inch.

High temperatures will be in the low to mid 50s countywide.

In the lower elevations, including most of the larger towns, northeast winds at 15-25 mph in the morning will increase to 20-30 mph sustained in the early afternoon and 30-40 mph sustained in the late afternoon. Gusts of 50-60 mph are possible in some locations. Wind speed will be highly dependent on elevation and whether location is along an east or west facing ridge. At higher elevations, wind speeds will likely be 35-45 mph with gusts to 70 mph during the late afternoon.

Monday Night

Rain, heavy at times in the evening. Rainfall will become more showery and lighter after midnight. Probability of precipitation 100%. Rainfall totals of 0.25 to 0.50 inches will fall mostly before midnight.

Temperatures will hold steady or even rise a few degrees as somewhat tropical air moves in with the storm.

The high winds discussed for Monday afternoon will hold through the evening hours and then diminish to 25-35 mph by midnight. Winds will shift to the east after midnight and diminish to 15-25 mph by daybreak. Some stronger gusts of 40-50 mph are still likely around midnight with gusts to 35 mph by daybreak.

Tuesday

Scattered showers, although we could get into a wedge of drier air for a time and the sun may even poke through. Probability of precipitation 80%. Rainfall totals of 0.10 to 0.25 inches.

It will be mild, with high temperatures near 60 in Pittsfield and North Adams, low 60s in Great Barrington and high 50s in the elevated terrain and hilltowns.

Southeast winds at 15-25 mph in the morning diminishing to 10-20 mph later in the afternoon. There could be a few gusts in the 30s (mph) early.

Things are coming into focus quite clearly in regard to the forecast for Sandy. The models are converging on a landfall somewhere along the New Jersey coast between late afternoon and evening on Monday (about 8 pm if you want to try to nail it down more specifically). The GFS model is still generating a very low pressure of around 950 mb when it makes landfall. As noted previously, the biggest impacts in regard to storm surge should be the New Jersey coast (particularly northern), NYC, Long Island and the southern New England coast. Storm surge models that I have looked at are generating about 5-10 foot storm surge for most locations. However, since landfall may occur near high tide on Monday evening, the actual water height may be as much as 12 feet above sea-level. One concern is the Delaware Bay. Fortunately, it is likely to be to the “left” of the storm track. However, the shape of the bay should funnel water in as it narrows toward the Delaware River. One model is predicting a 12-15 ft. storm surge there.

For Berkshire County, fortunately, storm surge is not a concern. In fact, there is some good news for us in the latest models. Most of the heaviest rainfall should occur to our south, with 5-10 inches occurring in some parts of NJ, PA, MD and DE. It looks like we will only receive about 1.00 – 1.50 inches from the initial bout of rain Monday night, with another 0.50 inches spread out over the next several days. Therefore, a repeat of the rainfall flooding New England saw with Irene does not appear likely at this time. Wind, however, is a different story, and that should be the biggest impact in our area. Our winds will not be as strong as along the coast (where there is little friction over water to slow the winds down). It needs to be noted that winds at 5000 ft are projected to be near 100 mph on Monday night so elevation will have a big impact on wind speeds. This is due to less surrounding land to exert friction at higher elevations. In the lower elevations of Berkshire County, including most of the large towns, sustained wind speeds of 25-35 mph with gusts to 50 mph are likely. However, at 2000 ft. elevation, 35-45 mph winds with gusts to 65 are possible. There may even be hurricane force (>75 mph) gusts in the highest elevations. The details are still uncertain, even though I am throwing numbers around like it was pizza dough, but the bottom line is that widespread power outages appear to be quite likely.

The timeline for Berkshire County looks like this right now: Showery rain beginning early Monday morning, likely before daybreak. The rainfall should remain relatively light to occasionally moderate through a good part of the day Monday. Rainfall will become heavy at times from late Monday afternoon through Monday evening. After midnight, the rain should diminish in intensity and become more showery, but will continue off and on into Wednesday. Showers are still likely on Wednesday and Thursday but will be much lighter. Total rainfall should be between 1.50 and 2.00 inches for most parts of Berkshire County, with about 1.00 to 1.25 inches of that occurring Monday afternoon and night. Wind speeds will increase throughout the day on Monday, reaching a peak on Monday evening. However, winds will fall of a bit after midnight but still remain strong throughout the night on Monday. Winds will diminish considerably on Tuesday as the storm begins to weaken dramatically after making landfall.

To reiterate, snowfall is not a concern for us with this storm. The only place snowfall is a concern is over the mountains of West Virginia and western Virginia and possibly in parts of Ohio. Our temperatures will be in the 50s from Monday through Tuesday and then fall into the 40s Tuesday night into Thursday. Temperatures may dip into the 30s Thursday night but the atmosphere will still not be cold enough to support snow. It is possible that it could be cold enough for a few flurries or snow showers on Friday or Friday night, but probably not.

The scenario from the European (ECMWF) model run from this morning is now very close to that of the GFS and NAM models with landfall of a very deep low, between 950 and 960 millibars, along the northern New Jersey coast in the early morning hours of Tuesday. It appears Berkshire County may be in for a bit of a rough ride Tuesday but not as dangerous as NYC, Long Island, and the southern and eastern New England coasts.

Summary: Results from the latest computer model run from the U.S. based Global Forecast System (GFS) form 12 UTC (8 am) are in and this model continues to generate a historically low central pressure in the surface low pressure system, of what is presently Hurricane Sandy, of near 950 mb. With each successive run that shows a similar outcome, it becomes more worrisome. Just to reiterate, this storm, which is presently a hurricane located over the Bahamas, continues to weaken as it encounters wind shear and cooler waters as it moves north. However, as mentioned in yesterdays post, the storm will begin to strengthen as it begins to draw energy from the jet stream and transitions to a midlatitude type storm. The reason that this storm is projected to become unusually strong is that it will retain much of the energy (latent heat) that it derived from the warm ocean as a tropical system while it draws additional energy (kinetic energy) from the jet stream as it transitions. It is, for the most part, irrelevant whether we call this storm a hurricane or a Nor’easter, or whatever. That only tells us about the structure of the storm and how it derives its energy. What we care about is how deep the low pressure at the center of the storm is, since the pressure “gradient” (how much the pressure changes over any given distance) determines how strong the wind will be, as well as how large the storm will be.  These two factors will combine to determine how large of a storm surge will be generated, and this is the most dangerous feature of any coastal storm. It still appears that the storm will have a very tight pressure gradient and will also be very large. As I discussed in the Introduction to Meteorology class this morning, the strongest winds and greatest surge are always to the right of the storm track. The GFS continues to bring the center of the storm onshore near eastern Long Island and the Connecticut Coast. If this were to hold true, then eastern LI, easter CT, RI, Cape Cod and the eastern Coast of New England would be in greatest danger.

The higher resolution North American Model (NAM), which only generates results out to 84 hours (due to its high resolution), now shows landfall at the end of its run. This model also shows landfall over Long Island but with central pressure of 960 mb (still very low) on Monday evening. The GFS has landfall early Tuesday morning. The results from the European model are not in yet and I will update this post when those results become available. In terms of possible impacts in Berkshire County, IF the storm does follow that track, we would likely have gale force winds with some gusts near or exceeding hurricane strength, with widespread power outages likely. Rainfall flooding would be a very big concern since we could receive 5 inches of rain, with locally heavier amounts. Fortunately, storm surge, the biggest fear in a coastal storm, is not an issue for us……

The weather timeline for Berkshire County for the following week is likely to progress as such: After the low level clouds “burn off” and it clears this afternoon, temperatures will warm into the 60s. However, with all of the low-level moisture (high dewpoints for this time of year) low clouds will likely develop again tonight. It will remain mild tomorrow but it will be very difficult to “burn off” the low clouds tomorrow as the sun becomes blocked by increasing high and mid-level clouds from the enormous cloud shield extending out from Sandy. It should be cloudy and cooler on Sunday but other than a few isolated sprinkles or light showers, we should remain rain free. Rain should begin to develop overnight Sunday or early Monday and become heavy at times Monday night into Wednesday. We will continue to have showers into Friday although the rainfall intensity will decrease markedly, starting on Wednesday as the storm stalls over the Northeast but weakens dramatically. Winds will begin to increase on Monday and will reach their peak on Tuesday but begin to die down considerably on Wednesday. Most of the rainfall, which at this point looks to be about 3-5 inches should have fallen by Wednesday morning. We will probably not see the sun again until sometime next weekend.

One note: I have been asked many times about snow with this system. Snow will not be an issue for us. There may be some snow over Ohio, western PA and West Virginia. It will become progressively cooler over the course of next week as the low becomes cut-off and the colder air from the trough mixes into the system. It will probably only be in the 40s later in the week for high temperatures.

Friday Night

Low clouds will build back in but it will remain mild.

Low temperatures will be near 50 countywide.

Southerly winds at 5-10 mph will shift to the southeast and become light after midnight.

Saturday

Mostly cloudy. Still unseasonably mild despite the cloud cover.

High temperatures near 60 in Pittsfield, Williamstown, Adams and North Adams, low 60s in South County and upper 50s over elevated terrain and the hilltowns.

Southeasterly winds at 5-10 mph.

Saturday Night

Remaining mostly cloudy and mild.

Low temperatures will again be near 50.

Easterly winds at 5-10 mph.

Sunday

Overcast and a bit cooler. It may even feel somewhat “raw” after the run of mild weather we have had. There is the chance of a few scattered sprinkles and light showers. Probability of precipitation 40%. Any precipitation totals should be under 0.05 inches.

High temperatures in the low to mid 50s in lower elevations of Central and Northern Berkshire, mid to upper 50s in South County and near 50 to low 50s over the elevated terrain, depending on elevation.

Northeasterly winds will increase to 10-20 mph in the afternoon with some gusts in the 20s.

Summary: The computer forecast models are beginning to converge somewhat on Hurricane Sandy. The exact track is still somewhat uncertain but most models now have landfall along the Northeast U.S. coast while Sandy is in the process of undergoing an “extratropical transition” from a tropical storm to a strong midlatitude cyclone (think Nor’easter). Landfall is most likely between the Delmarva Peninsula and the southern New England coast sometime late Monday into Tuesday. The European model (ECMWF), which has the best track record, has the storm making landfall along the southern New Jersey coast/Delmarva Peninsula region on Monday afternoon. This model has been very consistent with this track. This model generates a central pressure for the surface low in the 970-980 millibar (mb) range. This is quite deep and would be likely accompanied by gale force winds and coastal flooding and power outages. However, this scenario is unlikely to lead to a catastrophic outcome. The U.S. Global Forecast System (GFS) model generates a bit of a different scenario. It has the storm making landfall along the Long Island/southern Connecticut coast on Tuesday afternoon after it has undergone an “extratropical transition” and intensified profoundly due to its interaction with and extraction of energy from the jet stream. This model generates an enormous amount of divergence in the wind field at upper-levels of the troposphere (jet stream) above the storm on Monday and Tuesday while the storm is still out over the relatively warm waters of the Gulf Stream. Essentially, this divergence would create a vacuum at upper-levels that would suck air rapidly up and out of the atmospheric column above the surface storm causing a rapid drop in pressure. Since the storm would be over water where there is little friction so there would be little convergence at the bottom of the column to replace the air being evacuated from the top. The bottom line is that the GFS model generates a surface pressure between 940 and 950 mb. This is equivalent to the central pressure seen in a Category 3 hurricane and would create an enormous pressure gradient that could generate hurricane force winds and a very large storm surge. This scenario could, in fact, be catastrophic. However, before you think that I am engaging in hyperbole (just call me The Weather Channel), let me clarify by saying that I believe this “nightmare scenario” is not particularly likely. The situation does bear close monitoring over the next few days though. If the computer models begin to converge on this scenario than I think it would be wise to engage in enough hyperbole to get folks living along the coast, inland, and out of harms way. One scenario that does appear likely is that, as I noted yesterday, this storm should be very slow moving once it nears land and makes landfall. Therefore, there likely will be a prolonged period of rain, possibly through Thursday, and rainfall flooding would likely occur in the usual flooding prone river valleys. As of this point (4-7 days away), it appears that most areas could receive upwards of 2-3 inches of rain with upwards of 5 inches in some locations. More on all of this tomorrow……On a more boring note, our local weather is finally starting to improve with the sun poking out in most of the county this afternoon and temperatures reaching 60 in many locations. Sunshine should return with more vigor tomorrow as the warm front weakens and moves east and this will allow temperatures to reach 70 in many locations. It will remain mild on Saturday but begin to cloud up as the trough/cold front to our west inches eastward and then stalls to our west, awaiting the arrival of “Sandy”.

P.S. After writing this summary, the ECMWF run from this morning came in and the central pressure of the storm when it makes landfall is in the 950-960 mb range. Yikes! Me not liking this much. This model still has landfall near the Delmarva Peninsula sometime on Monday, even as early as Monday morning. More to come……

Thursday Night

Mostly cloudy and remaining mild.

Low temperatures will be near 50 countywide.

Winds light and variable.

Friday

Mostly cloudy early with increasing sunshine over the course of the morning. Becoming mostly sunny and unseasonably mild during the afternoon.

High temperatures in the upper 60s in Pittsfield, Williamstown, Adams and North Adams, low 70s in South County and mid 60s over elevated terrain and the hilltowns.

South-southwesterly winds at 5-10 mph.

Friday Night

Clear in the evening with an increase in clouds after midnight. Remaining unseasonably mild.

Low temperatures will again be near 50.

Calm winds.

Saturday

It will start out partly cloudy early in the morning. There will be an increase in clouds throughout the day. The cloud increase will involve high clouds at first, which will filter the sun, but these clouds will thicken and lower somewhat over the course of the afternoon. It should be mostly cloudy by late afternoon.

The cloud cover will likely keep it a few degrees cooler than Friday. High temperatures in the mid to upper 60s in lower elevations of Central and Northern Berkshire, near 70 in South County and low to mid 60s over the elevated terrain, depending on elevation.

Light north-northeasterly winds.

Summary: The warm front remains stalled just to our southwest and will remain so for the next 24-36 hours. Therefore, we will continue to “bask” under overcast skies and seasonably cool temperatures. We will not get to share in the sunshine and unseasonably warm temperatures that most of the eastern half of the country is enjoying. As the warm front finally “creeps” through Thursday night we will get only a taste of that subtropical airmass as skies become partly cloudy on Friday afternoon and temperatures climb well into the 60s. Unfortunately, although mild again on Saturday, it will begin to cloud up again as the cold front along the leading edge of the trough in the jet stream, which is presently causing snow over the Rockies, progresses slowly toward our region. However, the big upcoming weather story is likely to be Hurricane Sandy, presently hundreds of miles away, reeking havoc as it makes landfall on the island of Jamaica. It will continue its path of destruction over Cuba and the Bahamas, probably not strengthening much as it moves over multiple land masses. In fact, it is projected to decrease in intensity to a tropical storm as it moves over Cuba. It likely will strengthen to a minimal hurricane as it moves over the Bahamas and back into the Atlantic off the Southeast U.S. coast. It should then weaken again as it moves north over cooler water and begins to encounter more wind shear. It is unlikely to make landfall in the U.S. as a hurricane. However, it now appears to be a strong possibility that we will feel its impact starting late on Monday and possibly lasting for several days. Computer forecast model scenarios are still somewhat divergent, however, the most likely scenario is as follows: As Sandy tracks north to off the southeast U.S. coast it will weaken to a tropical storm. As the massive amount of latent heat being released into the atmosphere by this storm it will serve to build the warm ridge located over the eastern U.S.. This will amplify the entire wave pattern and cause the advancing trough from the western U.S. to dig further south. In fact, the trough will become what we call “negatively tilted” as it digs under the tropical storm. The resulting southeast flow along the eastern edge of this negatively tilted trough should redirect the tropical storm back towards the East Coast. During the day Monday and into Tuesday the tropical storm will begin to merge with the trough and come under the influence of the strong jet stream along its leading edge. The tropical storm should then undergo what is called an “extratropical transition” as it begins to derive its energy from the jet stream instead of the warm ocean waters. This should enable it to remain quite strong as it “backs up” over New England on Tuesday bringing heavy rains and strong winds well inland. It appears that the worst conditions may be on Tuesday. However, the jet stream wave pattern will likely become so amplified that the “negatively tilted” trough in the wave will “break” and become cut-off from the main jet stream. If this occurs, the cut-off low pressure system will become stacked vertically at all levels of the atmosphere. This will cause the surface storm to weaken but also stall over the northeastern U.S. giving us some rain and showers for several days, possibly even the majority of the week. However, much of this is conjecture, or, to be kind, an educated guess since all of this is almost a week away. So, as the TV guys always say, stay tuned for more updates………

Wednesday Night

Mostly cloudy, calm and mild for this time of year. There is a chance of nothing more than a few scattered sprinkles.

Temperatures will not drop much given the cloud cover and should bottom out in the mid 40s.

Calm winds.

Thursday

Mostly cloudy although the sun will start to peek through from time to time during the afternoon, particularly late.

It will be slightly milder than Wednesday with high temperatures near 60 in Pittsfield and North Adams, low 60s in Great Barrington and mid to upper 50s over elevated terrain and the hilltowns, depending on elevation.

Southeast winds in the morning shifting to south in the afternoon at 5-10 mph.

Thursday Night

Remaining mostly cloudy.

Temperatures again will not drop much with the cloud cover. In addition, dewpoints will begin to rise as the milder, moister air starts to move in with the passage of the warm front. Low temperatures should be near 50 in most areas.

Light southerly winds.

Friday

It will start out mostly cloudy in the morning but skies should begin to clear late morning, becoming partly cloudy in the afternoon.

It will be milder, with high temperatures well into the 60s. Highs should reach the mid to upper 60s in most areas but only low 60s in the elevated terrain. If we get enough sunshine it could hit 70 in some parts of South County.

Light south-southwest winds.

Summary: The change in the jet stream pattern which had been anticipated last week is presently taking place. Unfortunately, this change is stuck in transition directly over our region. A large southward plunge in the jet stream wave pattern (trough) over the Western U.S. has brought some rain to California and snow to the Rockies with much cooler temperatures. In response, the jet stream wave pattern has lifted to the north (ridge) over the Eastern U.S.. This is bringing much warmer temperatures to the Midwest and most of the East Coast. Temperatures have surged into the unseasonable 70s and 80s. Unfortunately, the trough which is lifting out of our region is taking its sweet time and, effectively, is blocking the northward surge of the ridge. So, we are caught between the trough and the ridge which is manifested as a surface warm front which is stalling just to the southwest of Berkshire County. The lighter warm air (80 degrees in Pittsburgh!!) is trying to advance north but is unable to budge the heavier cooler air over New England (temps in the 50s), so it is riding up over it, causing cloud formation and a band of rain and showers to develop today. As the front stalls, we will be stuck in the clouds, with relatively cool and moist air (temperatures still are slightly above normal for this time of year) for the next 48 hours or so. Hopefully, the front will finally push through to our northeast later on Thursday. This should allow at least some sunshine and warmer temperatures to move in for Friday and Saturday. In fact, temperatures could crack the 70 degree mark on both days before a strong cold front moves through late on Saturday. We may actually have below average temperatures early next week, but that is still a long way off.

Tuesday Night

Overcast with showers likely in the evening. Probability of precipitation 90% in South County, 80% in Central Berkshire but only 50% in North County as the northern edge of the precipitation shield associated with the warm front, while giving northern areas some showers this afternoon, will shift south in the evening and may not reach the Vermont border and may even stay south of Williamstown and North Adams during the nighttime hours. Precipitation totals will likely be between 0.10 and 0.25 inches with the heaviest totals to the south. The steadier rain should end near midnight with only a chance of scattered light showers after midnight.

Low temperatures in the low to mid 40s.

Light and variable winds becoming calm.

Wednesday

Overcast and seasonably cool. There may be a few scattered sprinkles and some drizzle but it will be mostly dry.

High temperatures in the mid 50s in Pittsfield and North Adams, upper 50s in Great Barrington and low 50s over elevated terrain and the hilltowns.

Light north-northeasterly winds.

Wednesday Night

Remaining cloudy with a few scattered areas of drizzle or sprinkles.

Low temperatures generally in the mid 40s.

Calm winds.

Thursday

Mostly cloudy. There may be a few peeks of sun later in the afternoon. There may be some lingering drizzle in the morning.

It will remain seasonably cool but will likely be a few degrees warmer than Wednesday with high temperatures in the upper 50s in Pittsfield and North Adams, near 60 in Sheffield and Great Barrington and mid 50s over the elevated terrain and hilltowns.

Southeasterly winds at 5-10 mph.