8:19PM

As expected, the center of Irene is back over water, east of Virginia Beach, as of 8PM. I am going to continue to forecast the center spending most of its time over warm water just off the Delmarva/NJ coast tonight, making landfall late tomorrow morning in western Long Island before cutting across western CT and central MA into NH during the day.

Specifics…

Rain: Tropical downpours all areas tonight, heaviest steady rain west of the storm track, more showery east of it. Rainfall amounts 1-4 inches east of the track, 4-8 inches to the west, with locally heavier amounts. River flooding most likely in the heavy rain areas to the west. Flash flooding problems may occur anywhere when heavy rain occurs over a short period of time.

Wind: East of the storm track, winds mostly from the southeast to south, often tropical storm force, top gusts 40-60 MPH with locally stronger, except gusts around hurricane force likely along the South Coast and some of the higher elevations (Blue Hill, for example). The strongest winds should occur from shortly after dawn on Sunday until shortly after sunset Sunday evening, but strong gusts may continue as the wind shifts more to the west in areas that were east of the storm track well into the night and early Monday morning. West of the track, expect northeast to north winds 15-35 MPH with higher gusts, but strongest winds there will be northwest to west behind the storm, 25-40 MPH with stronger gusts, likely over 50 MPH for a period of time Sunday evening. Considerable tree damage is expected from this event, because it has been a while since such a storm, and the ground is saturated from heavy rain before the storm, making the soil softer around bases off trees.

Storm Surge: Same as previous, 4 to potentially 8 foot storm surge flooding at the times of high tide, especially south facing bay areas along the South Coast. Coastal flooding is likely elsewhere, but not as severe.

Tornadoes: Isolated tornadoes are possible in heavier rain bands especially Sunday morning and midday and especially over eastern and southeastern Massachusetts. These are usually very weak and short-lived, but still significant enough to add to wind damage. For more on the cause of these kinds of tornadoes, see previous entries.

Updated Boston Area Forecast…

TONIGHT: Cloudy. Episodes of tropical showers, heavy at times. Chance of thunderstorms. Areas of fog, possibly dense at times. Low 64-69. Wind SE to S 5-15 MPH increasing to 15-35 MPH with higher gusts around dawn from south to north.

SUNDAY: Mostly cloudy. Tropical showers most numerous in the morning, likely heavy at times with a chance of thunderstorms as well. Brief intervals of sunshine may pop out between the downpours over the Boston area and points to the south. Mild with tropical humidity. High 70-75. Wind SE to S 25-45 MPH with gusts 40-60 MPH and even slightly higher, favoring higher elevations and coastal areas. Winds shift more SW to W during the afternoon. Isolated brief tornadoes possible through mid afternoon.

SUNDAY NIGHT: Rain and showers ending from south to north with breaking clouds following. Still mild and very humid. Low 65-70. Wind W 15-35 MPH with gusts over 40 MPH, still may reach around 50 MPH over exposed higher elevations.

MONDAY: Mostly sunny. Warm and humid. High 80-85. Wind W 15-30 MPH early, diminishing slowly.

TUESDAY: Sunny. Low 58. High 79.

WEDNESDAY: Sunny. Low 56. High 78.

THURSDAY: Mostly sunny. Low 62. High 83.

FRIDAY: Partly sunny. Low 63. High 82.

12:31PM

The center of Hurricane Irene is over eastern North Carolina, which is weakening the system somewhat. It maintains Category 1 hurricane intensity, however. We have seen the storm move more to the north during the morning, but that northward movement has slowed, and that indicates it was more of a track wobble. Expect the center to shift briefly to the east then take a more north northeast track, and should be partly to mostly over water just east of Norfolk, Virginia, by this evening.

The changes I am making are more in timing than intensity. I think we should see a minimal category 1 hurricane making landfall on Long Island NY, but as I now expect a little faster acceleration, this landfall will take place Sunday afternoon. I’m going to hold the same track for now, despite the NHC track being shifted a bit west. There is a trough approaching from the west but enough southwesterly flow ahead of it, though causing the hurricane to become less organized, may also kick the center a little more east with time. Its faster acceleration washes out the decrease in wind due to weakening on the east side. Because of this I will continue with the same forecast regarding wind gusts and storm surge. We may see the 8 feet becoming less likely and closer to the 4 being more of a reality, but I’ll leave the range the same for now, in case.

So overall, no great changes to the forecast, other than just a little faster beginning and ending. And don’t forget that strong winds are still possible on the back side as the storm moves away.

Updated Boston Area Forecast…

THIS AFTERNOON: Mostly cloudy. Scattered showers, a few possibly heavy. Slight chance of thunderstorms. Mild and very humid. High 74-79. Wind S to SE 5-15 MPH.

TONIGHT: Cloudy. Episodes of tropical showers, heavy at times. Chance of thunderstorms. Areas of fog, possibly dense at times. Low 64-69. Wind SE to S 5-15 MPH.

SUNDAY: Mostly cloudy. Tropical showers most numerous in the morning, likely heavy at times with a chance of thunderstorms as well. Brief intervals of sunshine may pop out between the downpours over the Boston area and points to the south. Mild with tropical humidity. High 70-75. Wind SE to S 15-25 MPH increasing to 25-45 MPH with gusts 50 MPH or higher becoming quite common, shifting more to the W during the afternoon. Hurricane-force gusts are still possible over higher elevations and mainly south-facing coastal areas. Isolated tornadoes are possible especially from morning through mid afternoon.

SUNDAY NIGHT: Rain and showers ending from south to north with breaking clouds following. Still mild and very humid. Low 65-70. Wind W 15-35 MPH with gusts over 40 MPH.

MONDAY: Mostly sunny. Warm and humid. High 80-85. Wind W 15-30 MPH and gusty, diminishing slowly.

TUESDAY: Sunny. Low 58. High 79.

WEDNESDAY: Sunny. Low 56. High 78.

THURSDAY: Mostly sunny. Low 62. High 83.

FRIDAY: Partly sunny. Low 63. High 82.

3:30AM

As of 3AM, Hurricane Irene’s top winds are down slightly to 90 MPH as it moves NNE along the North Carolina Coast.

What is hurting Irene? She felt some southwesterly wind sheer from a trough of low pressure over the Gulf of Mexico during the past 24 hours, but has now gotten beyond that. The circulation being partly over land interrupts the even inflow to the storm. Some dry air has also worked into the western part of the circulation, making it look irregular.

What will aid Irene? The center of the hurricane should remain mostly over water as it moves away from NC later Saturday. The water temperatures are quite warm right up to Long Island NY.

When is storm for the Boston area? Although tropical showers are possible today, the heaviest tropical rain will occur tonight and Sunday morning, and the strongest wind will occur Sunday afternoon and evening.

Tornadoes? As noted in the previous blog post, tropical cyclones can and do produce tornadoes when they come over land. This takes place because friction encountered by the storm over land lowers the wind speed there, while the winds just above remain stronger. This results in wind sheer, which can be explained as differences in wind speed and direction as you go from the ground up. These differences create the rotation that becomes tornadoes. These are usually embedded in some of the rain bands on the right front quadrant of the storm, or in this case, to the northeast of where the center is. Hurricane-produced tornadoes are weaker than their severe thunderstorm cousins, but can cause significant damage. Do not be surprised if a tornado watch is issued for at least the eastern half of MA including RI and southern NH by the National Weather Service on Sunday.

Where is the center of Irene going? I believe Long Island landfall will take place slightly earlier than I said on the previous post, by 6PM Sunday at the latest. I’m edging my forecast track east very slightly, based on the fact that the hurricane had already turned to the north northeast as of late Friday night and is not expected to turn back to north, but continue north northeast. The center will probably cross central Connecticut and Massachusetts, passing over or just west of Worcester by 8PM. One change in my thinking from earlier is that the air mass will be very tropical and with water temperatures quite warm right up to long island, it may take a little longer for Irene to start losing tropical characteristics. Once it gets into northern New England later Sunday night, it will start to transition into a regular storm, at which time the winds around the storm, though weakening, may expand and cover a larger area. How rapidly this takes place will determine how much wind lingers over southern New England after the storm leaves. Keep in mind that strong and gusty winds may continue into Monday, even though the storm will be long gone by then.

Wind? East of the center, expect tropical storm-force winds (39-73 MPH)with the potential for hurricane-force gusts (74 MPH or higher), strongest near the coast and over higher elevations. Winds will blow mostly from the south southeast to south in the big wind regions. West of the center, winds will be mostly east to northeast as the storm approaches, shifting to north and northwest as it passes, and may be strong and gusty at times, with possibly the strongest winds coming as the storm is departing Sunday night.

Rain? Tropical showers and possible thunderstorms, with some heavy rain bands, will result in around 1 to as much as 3 inches of rain in eastern areas, east of the center. Amounts will be much heavier to the west of the center, with 4 to 7 inches of rain common. Amounts of over 7 inches may occur in some up-sloping wind regions in western Massachusetts and then up into portions of northern New England.

Coastal storm surge & flooding? East-facing coastal areas will see splashover and flooding especially at high tide, but should not be any worse than during powerful winter storms.  South-facing areas, especially the bays of the South Coast, will see storm surge flooding as high as 4 to 8 feet. Significant flooding is likely in these areas.

I hope this breakdown of the storm covers just about everything. If you have any questions, do not hesitate to post them in the comments section below.

Beyond Irene? Well it looks like a great stretch of weather follows this storm for the first half of next week!

Updated Boston Area Forecast…

TODAY: Mostly cloudy to partly sunny, warm, and very humid. Isolated showers in the morning. Scattered showers in the afternoon, a few of which may be heavy. High 73-78. Wind S to SE 5-15 MPH.

TONIGHT: Cloudy. Episodes of tropical showers, heavy at times. Chance of thunderstorms. Areas of fog, possibly dense at times. Low 64-69. Wind SE to S 5-15 MPH.

SUNDAY: Overcast. Fog possible in the morning. Tropical showers most numerous in the morning, likely heavy at times with a chance of thunderstorms as well. Showers may become less numerous for a time in the afternoon, but a core of heavier rain is expected later in the afternoon.  Mild with tropical humidity. High 70-75. Wind SE to S 15-25 MPH increasing to 25-45 MPH with gusts 50 MPH or higher becoming quite common, possibly up to 75 MPH or slightly higher over coastal and higher elevations by late in the day. Isolated tornadoes are possible, but not likely.

SUNDAY NIGHT: Rain and showers ending from south to north with breaking clouds following. Still mild and very humid. Low 65-70. Wind SW to W 15-35 MPH with gusts 45-55 MPH.

MONDAY: Mostly sunny. Warm and humid. High 80-85. Wind W 15-30 MPH and gusty, diminishing slowly.

TUESDAY: Sunny. Low 58. High 79.

WEDNESDAY: Sunny. Low 56. High 78.

THURSDAY: Mostly sunny. Low 62. High 83.

FRIDAY: Partly sunny. Low 63. High 82.

8:03AM

A trend back east with Irene’s track on some of the major computer models indicates they are correcting their too-far-westward shift of the day before, in my opinion, and we’ll be happy at this point we did not jump on the “westward-ho-go-the-models” band wagon. Don’t like to do it with winter storms, don’t like to do it with tropical cyclones. So all in all the same general idea applies on this morning’s forecast. Irene will skirt NC and move N to NNE just offshore the Delmarva & NJ during the next couple of days on its way to an eventual Long Island NY & South Coast of New England landfall late Sunday, and from there a path across MA, odds favoring central parts of the state, and on into NH and Maine, then long gone by the late night of Sunday when the stars may already be shining. And as we have been talking about in the discussions and comments, this should be a classic New England hurricane, losing tropical characteristics as it accelerates through, but maintaining enough strength to be significant, with the eastern side being the big wind side (along with the storm surge at the coast), and the western side being the big rain side.

Don’t forget that hurricanes and tropical storms can produce isolated tornadoes, especially on their eastern sides when moving northward. This is not meant to alarm anybody, but just to make you aware that they are possible.

This is by no means the final call on Irene’s path! There are still conditions that exist that can effect both the track and expected strength of this hurricane.

Look for updates during the course of the day in the comments section below, mostly from some of my readers, as I will be out of town most of the day (will check in via mobile).

Updated Boston Area Forecast…

TODAY: Mostly sunny, warm, and humid. High 81-86. Wind W up to 10 MPH shifting to S.

TONIGHT: Partly cloudy, mild, and muggy. Low 64-69. Wind S up to 10 MPH.

SATURDAY: Mostly cloudy, warm, and very humid. Isolated showers in the morning. Scattered showers in the afternoon, a few of which may be heavy. High 73-78. Wind S to SE 5-15 MPH.

SATURDAY NIGHT: Cloudy. Episodes of tropical showers, heavy at times. Chance of thunderstorms. Areas of fog, possibly dense at times. Low 64-69. Wind SE to S 5-15 MPH.

SUNDAY: Overcast. Fog possible in the morning. Tropical showers most numerous in the morning, likely heavy at times with a chance of thunderstorms as well. Showers may become less numerous for a time in the afternoon before a core of heavy rain approaches from the SSW as early as the end of the afternoon or early evening. Mild with tropical humidity. High 70-75. Wind varying from SE to S mostly 10-20 MPH during the day with higher gusts, increasing to 25-45 MPH and stronger with powerful gusts possible in the evening, greatest chance of strong tropical storm to hurricane force wind gusts will be at coastal and higher elevations. Isolated tornadoes are possible, but not likely.

SUNDAY NIGHT: Conditions the same as Sunday evening before improving as rain ends from south to north and clouds break during the night. Still mild and very humid. Low 65-70. Wind, dependent on the exact path, should shift from S to SW then W at least 25-45 MPH sustained, possibly stronger, with higher gusts (these directions could change if the center of the storm is closer, and we will detail that as things become more clear, closer to the event).

MONDAY: Mostly sunny. Warm and humid. High 80-85. Wind W 15-30 MPH and gusty, diminishing slowly.

TUESDAY: Sunny. Low 58. High 79.

WEDNESDAY: Sunny. Low 56. High 78.

THURSDAY: Mostly sunny. Low 62. High 83.

FRIDAY: Partly sunny. Low 63. High 82.

9:59PM

A line of showers and thunderstorms will march eastward across eastern MA between 10PM & shortly after midnight (a bit later southeast of Boston). The heaviest activity will likely occur along and south of the Mass Pike, but areas to the north could see some downpours, lightning, thunder, and gusty winds as well.

For more on the weather and Irene, see previous discussion. Update coming after midnight.

Boston Area Forecast Update…

TONIGHT: Showers and storms crossing the region through 1AM, then just a slight risk of a passing shower or storm overnight. Muggy. Low 63-68. Wind shifting to W 5-15 MPH. Strong, gusty winds are possible near storms.

FRIDAY: Partly to mostly sunny. Humid. High 82-87. Wind W 5-15 MPH shifting to S.

SATURDAY: Mostly cloudy. Chance of showers, some of which may be heavy especially at night. Low 66. High 80.

SUNDAY: Cloudy. Showery rains, heavy at times. Chance of thunder. Increasing wind, possibly damaging wind late day into nighttime hours, depending on exact path of Irene. Low 66. High 76.

MONDAY: Mostly sunny and windy. Low 61. High 82.

TUESDAY: Sunny. Low 58. High 79.

WEDNESDAY: Sunny. Low 58. High 79.

3:47PM

Short discussion now, longer one later.

Cold front moving into New England now, bumping into muggy air in place. This will set off showers and thunderstorms into tonight, a few of which may be strong to severe, so keep an eye out!

High pressure brings nicer weather Friday. Still looking for clouds and eventually showers on Saturday in advance of Irene as the old frontal boundary drifts back over the region. Regarding Irene, please check the latest advisories from the National Weather Service and read the comments section below as many of the readers provide great links, ideas, and commentary on what is going on. I am not going to drastically change my forecast track on it, however I am shifting it back west a bit, keeping the center a little closer to the Mid Atlantic Coast, and thinking it may cross Long Island’s western half before heading through CT and western or central MA. I am not convinced we don’t see a slight adjustment eastward by the models, as they adjusted westward during the past 24 hours – reminds me of winter storm model forecasts…ugh. So for now I buy a little of the westward shift, but not fully. (For my model-viewing readers, my track is similar to the 12z NAM at the moment.)

Boston Area Forecast…

REMAINDER OF AFTERNOON: Mostly cloudy with scattered showers and thunderstorms. Any storms may be strong with a slight risk of a severe storm. Muggy. Temperature near 80 but cooling through the 70s during any showers and storms. Wind S to SW 10-20 MPH with higher gusts.

TONIGHT: Showers and storms remain possible until 11PM then breaking clouds but patchy fog. Still muggy. Low 63-68. Wind shifting to W 5-15 MPH.

FRIDAY: Partly to mostly sunny. Humid. High 82-87. Wind W 5-15 MPH shifting to S.

SATURDAY: Mostly cloudy. Chance of showers, some of which may be heavy especially at night. Low 66. High 80.

SUNDAY: Cloudy. Showery rains, heavy at times. Chance of thunder. Increasing wind, possibly damaging wind late day into nighttime hours, depending on exact path of Irene. Low 66. High 76.

MONDAY: Mostly sunny and windy. Low 61. High 82.

TUESDAY: Sunny. Low 58. High 79.

WEDNESDAY: Sunny. Low 58. High 79.

3:35PM

High pressure has slipped offshore and a southerly flow behind it is bringing in increasing humidity with some clouds, though it has been and remains a generally nice day across southern New England. A cold front will amble its way into and across New England from west to east Thursday and Thursday night, bringing a risk of showers and thunderstorms. The main activity should occur just ahead of and along the front itself during the night. High pressure will build in on Friday bringing nice weather for a day, but the front from the night before will not be far offshore, and the boundary left behind by it will drift back toward the coast by Saturday, setting up a conveyor belt for tropical moisture in advance of Hurricane Irene. This means that showers may break out during Saturday, and by Saturday evening or night, some of them may be heavy. This will not be directly associated with Irene. We will feel the first rain bands from that during the day on Sunday. Irene’s closest pass is expected Sunday evening. There, of course, is still uncertainty on the final track. If you look at yesterday’s blog post I wrote a “for fun” scenario in the comments section, based on my actual thoughts. This still holds, and for the moment is similar to the track issued by the National Weather Service. This track brought Irene close to the Outer Banks of North Carolina on Saturday then accelerated it north northeast to the eastern tip of Long Island NY and then into the South Coast of New England near the border of Rhode Island and Connecticut by late Sunday afternoon or early Sunday night. Tropical cyclones that have turned to the north along or off the US East Coast often accelerate very rapidly and start to lose tropical characteristics, but history has shown they can still pack quite a punch. In this case, Irene is expected to behave like the majority of these systems. I expect it to reach southern New England as a strong Category 1 or weak Category 2 hurricane. If it were to scrape NC a little further inland than the outer banks or remain near the Delmarva Coast longer, it would weaken a little more due to its proximity to land (interaction with land weakens these storms – they like warm water). If the center remains offshore, it will maintain alot of its intensity, though weaken some, as the water is running warmer than normal at this time. So it all comes down to the details of the track. Anyone east of the track will see stronger winds, and bands of heavy rain, though not tremendous rainfall totals in most cases. Coastal areas east of the center, especially south-facing ones, face a storm surge of at least a few feet, which would lead to flooding. Wind damage is also most likely in these areas. Those who are west of the path will see much less wind but a heavier swath of rain. Wind damage is still possible here but would be much less widespread. However, the heavy rain could aid in bringing down some trees that were weakened by previous heavy rain, and even weakened by some of last winter’s storms.

I believe that Irene will be accelerating so quickly, that most if not all rain will be over by Sunday night at midnight, and the stars may even be visible through breaks in the clouds here in southern New England.

It should also be noted that landfalling tropical cyclones (tropical storms and hurricanes, and even depressions) can produce tornadoes. These are usually weaker than the type produced by severe thunderstorms, but are still capable of producing significant damage. These are most likely on the side of the storm that would be east of the center. Something to keep in mind if any part of southern New England is east of the center.

Check back here for further updates on Irene and please feel free to join in the discussion below, in the comments section!

In the mean time, here is my latest forecast for the Boston Area and nearby neighbors…

REMAINDER OF AFTERNOON: Mostly cloudy to partly sunny. Temperature settling from near 80 into the 70s. Wind S 10-20 MPH.

TONIGHT: Partly cloudy. Low 63-68. Wind S 10-20 MPH with higher gusts.

THURSDAY: Variably cloudy. Scattered showers and possible thunderstorms after 10AM. High 81-86. Wind S 10-20 MPH shifting to SW late in the day.

THURSDAY NIGHT: Mostly cloudy. Scattered showers early. A band of showers and locally heavier thunderstorms crossing the region from west to east about 10PM-2AM. Low 61-66. Wind SW 10-20 MPH shifting to W overnight.

FRIDAY: Partly cloudy to mostly sunny. High 82-87. Wind W 5-15 MPH.

SATURDAY: Mostly cloudy. Slight chance of showers in the morning. Increasing chance of showers in the afternoon. Chance of thunderstorms. Low 64. High 80.

SUNDAY: Cloudy. Tropical showers likely, some heavy. Possible thunder. Strong winds and heavy rain possible from late afternoon into evening depending on the exact track of Irene. Low 66. High 77.

MONDAY: Mostly sunny. Low 60. High 84.

TUESDAY: Partly sunny. Low 60. High 80.

WEDNESDAY: Partly cloudy. Low 55. High 78.

4:07PM

This post is just a quick updated forecast for the Boston area, and also to provide fresh space for anybody to discuss the weather, especially Irene, as well as today’s earthquakes (Virginia & Colorado). A full discussion with my latest thoughts on Irene will be posted this evening. For now, my quick summary of it is that the storm will be brushing the Carolinas before heading for New England. Where does it enter New England? Remains to be seen, but I’m very close to agreeing with one of my colleagues who has been calling for Ocracoke NC & Falmouth MA for a few days now. Time frame for Irene’s impact on the Boston Area is Sunday-early Monday. Saturday is no longer in the time frame.

Boston Area Forecast…

TONIGHT: Partly cloudy. Low 55-60. Wind W 5-10 MPH.

WEDNESDAY: Mostly sunny. High 80-85. Wind SW 10-20 MPH.

WEDNESDAY NIGHT: Partly cloudy. Low 60-65. Wind S 5-15 MPH.

THURSDAY: Partly sunny. PM showers/thunderstorms. Low 66. High 86.

FRIDAY: Partly cloudy. Low 62. High 82.

SATURDAY: Partly sunny. Low 64. High 84.

SUNDAY: Clouding up. PM showers. Rain/wind at night. Low 66. High 76.

MONDAY: Early rain, then clearing. Windy. Low 66. High 79.

3:12PM

Before I get to an updated forecast for eastern MA and nearby neighbors, I would like to thank the many of you that have voted for this blog on WBZ TV’s contest. Please continue to vote! I am overwhelmed by the support I’ve received!

What did happen?

Last night, many of you may have heard heavy rain falling around 2:30-3:30AM in Metro Boston. I had forecast thunderstorms to possibly enter the region around that time and bring heavy rain.  But the truth is, the heavy rain was not from the line I was expecting, but an area of heavy rain that developed and moved in from the south southwest. During this time, the line to the west weakened and slowed down. So this was a case of being right (the rain) for the wrong reason (not from what I expected).

What is happening?

Oh, what a great day today! After clouds to start, sunshine has taken over, and is shining brightly other than when a fair weather cloud passes in front of it. The humidity has dropped but along with that we have a gusty westerly breeze to deal with, maybe a little strong for playing a game of cards outside, but refreshing either way. Despite the beautiful day ongoing, we do have one more disturbance that has to pass by from the northwest later this afternoon and evening, so you may notice some increase in clouds and there is also the slightest risk of a passing shower in a few locations.

What is coming up the next few days?

Once this disturbance exits tonight, the dry air will be reinforced through Tuesday, which will be a bright but with a cool morning and pleasantly mild afternoon, with very low humidity. It will not be as breezy as today as the center of high pressure will be much closer. High clouds will move in later in the day and especially at night, when they may thicken for a while (showers may cross the northern mountains but it should remain dry in southern New England). This will be a warm front passing through the region. This front will be beyond us by Wednesday, which will turn out to be a mostly sunny and warmer day, with a slight but not-too-noticeable increase in humidity. That will occur later at night and especially Thursday ahead of a cold front, which will set off some showers and thunderstorms at some point Thursday or Thursday night. This front is expected to head offshore by Friday when high pressure moves in, bringing fair weather.

The weekend? Irene?

There is too much uncertainty regarding the path and strength of Hurricane Irene to determine just what it will do to this area and when that will occur. So instead of getting sucked into the hype vortex that you can find just about anywhere you look, I’ll just keep it real simple and say this. I am pretty certain we will hear from Irene at some point between Saturday and Monday. I do not know how strong it will be when it gets here and how much rain and/or wind we will see. We need to keep a very close eye on this storm, either way, because there is the potential for a significant impact from it.

Updated Boston Area Forecast…

REMAINDER OF DAYLIGHT: Becoming partly cloudy. A very slight chance of a shower early in the evening though most areas will remain dry. Temperature cooling through the 70s. Wind W 10-20 MPH with gusts as high as 25 MPH.

TONIGHT: Partly cloudy early, then clear. Low 52-57. Wind NW 5-15 MPH, diminishing.

TUESDAY: Sunshine, may becoming filtered by increasing high clouds by late afternoon. High 75-80. Wind NW 5-15 MPH.

TUESDAY NIGHT: Partly to mostly cloudy. Low 55-60. Wind variable under 10 MPH.

WEDNESDAY: Partly to mostly sunny. High 80-85. Wind SW 5-15 MPH.

THURSDAY: Scattered showers/thunderstorms. Low 64. High 86.

FRIDAY: Partly sunny. Low 66. High 83.

SATURDAY: Partly cloudy. Low 64. High 83.

SUNDAY: Clouding up. Chance of rain/wind. Low 66. High 76.

MONDAY: Chance of rain or showers then clearing. Low 66. High 79.

NOTE: The SATURDAY-MONDAY period is with low confidence in details and will depend on the track of Irene.

11:13PM

The “South Wind Storm Killer” has been at work tonight, keeping organized storms from reaching the coastal plain in eastern MA, RI, and the Seacoast region of NH. Often, a straight southerly wind will keep the atmosphere too stable to support strong storms, and only isolated heavy downpours pop up in the tropical air that is over us. A subtle shift in conditions over the next few hours may allow a line of storms currently entering east central NY State (as of 10:30PM) to make it most of if not all of the way across MA by 3:00AM.  Winds should shift to the southwest ahead of this line, and the sooner that happens the better the chance is that these storms survive the trip. If the winds remain more southerly, then this line will also weaken as it moves into the stabilized air in place. So don’t be totally surprised if you hear at least heavy rain falling and possibly some booming thunder sometime between 2:00AM & 4:00AM, earliest to the west, lastly in areas southeast of Boston. All of this activity should be pushing eastward offshore by dawn.

Looking ahead into the new week, we still have a little bit of an upper level trough to cross the region on Monday, and perhaps also one weak wave of low pressure rippling along the front that will have just passed by, so we cannot completely rule out a shower or thunderstorm through Monday evening, though widespread activity is not expected.

High pressure will dominate Tuesday and Wednesday with 2 splendid late summer days being the result.

By Thursday, we’ll be back into return flow on the back side of high pressure, and will see an increase in temperature and humidity, and also the chance of showers and thunderstorms, most likely later in the day or at night, as a cold front moves into the region. This front should push offshore Friday with a return to fair weather, which should last through Saturday as well. Things become tricky by Sunday as that could be when we’d be hearing from Irene, currently a tropical storm and expected to become a hurricane. I could outline multiple scenarios, based on computer model forecasts, but at this point I will just say that the storm will likely impact somewhere along the Southeast US Coast as a hurricane late in the week, and it should arrive in the Northeast via south to north steering currents by late in the weekend. What form Irene will be in when it gets here? It is simply too early to tell, and this will be something to follow during the week.

A peek a little further ahead into the last few days of August: Looks great behind Irene for the last couple days of the month, and there are even some early signs of a bout of late summer heat as we head toward the Labor Day Weekend. More in the days to come…

For now, the latest Boston Area Forecast…

OVERNIGHT: Mostly cloudy, mild, and muggy. Isolated to scattered showers and thunderstorms through 2AM, then a chance of a broken to solid line of showers and storms moving west to east across the region between 2AM & 4AM. A follow up shower or storm may visit areas especially along and east of Route 95 toward dawn. Low 64-69. Wind S 10-15 MPH with higher gusts, shifting to SW, then W toward dawn.

MONDAY: Mostly cloudy to partly sunny with a lingering shower possible in the morning. Mostly sunny to partly cloudy in the afternoon then variably cloudy late in the day with a risk of a passing shower or thunderstorm. High 80-85. Starting humid then slowly drying. Wind W 10-15 MPH with gusts around 20 MPH, shifting to NW.

MONDAY NIGHT: Partly cloudy. Cooler and drier. Low 60-65. Wind NW 5-15 MPH.

TUESDAY: Mostly sunny and comfortable. High 75-80. Wind NW 5-15 MPH.

WEDNESDAY: Mostly sunny. Low 60. High 81.

THURSDAY: Partly cloudy. PM thunderstorms. Low 66. High 88.

FRIDAY: Partly sunny. Low 64. High 82.

SATURDAY: Mostly sunny. Low 64. High 84.

SUNDAY: Clouding over. Rain/wind arriving (Irene)? Low 66. High 77.

10:38AM

This is the last update based on the last full discussion. The next blog post will feature an outlook for the week ahead including an extended look at the longer term trends as we head for the finish line of August.

Boston Area Forecast…

TODAY: Partly sunny. Scattered showers and thunderstorms possible in the afternoon. More organized lines of showers and storms should approach from the west by evening. Any storms after 3PM may be strong to locally severe. High 82-87. Wind S 10-20 MPH.

TONIGHT: Mostly cloudy. Episodes of showers and thunderstorms, some possibly severe, with the strongest activity most likely before 2AM. Low 63-68. Wind SW 5-15 MPH. However, strong and gusty winds are possible near any thunderstorms.

MONDAY: Variably cloudy. Lingering showers and thunderstorms possible early morning. Isolated showers and thunderstorms are possible in the afternoon through early evening. High 80-85. Wind W 5-15 MPH shifting to NW.

TUESDAY: Mostly sunny. Low 59. High 80.

WEDNESDAY: Partly cloudy. Low 62. High 84.

THURSDAY: Partly sunny. Showers and thunderstorms late. Low 66. High 88.

FRIDAY: Partly cloudy. Low 64. High 81.

*** NOTE *** Additional posts may appear regarding the severe weather threat, otherwise look for observations and updates in the comments section of this blog post below. Also feel free to post a comment with any questions or observations you have, not just today, but any time!

9:16AM

Boston Area Forecast…

TODAY: Partly cloudy. Slight chance of isolated showers and thunderstorms in the afternoon. High 83-88. Wind S up to 10 MPH.

TONIGHT: Partly cloudy. Low 63-68. Wind S up to 10 MPH.

SUNDAY: Partly sunny. Scattered showers and thunderstorms in the afternoon. High 83-88. Wind SW increasing to 10-20 MPH with higher gusts.

SUNDAY NIGHT: Mostly cloudy. Showers and thunderstorms likely, probably coming in 2 or 3 waves of activity. Storms may be strong to severe. Low 63-68. Wind SW 5-15 MPH with higher gusts, except possible strong winds associated with some thunderstorms.

MONDAY: Partly sunny. Chance of showers in the morning. High 80-85. Wind W to NW 5-15 MPH.

TUESDAY: Mostly sunny. Low 59. High 80.

WEDNESDAY: Mostly sunny. Low 60. High 82.

THURSDAY: PM thunderstorms. Low 66. High 88.

FRIDAY: AM showers. Low 66. High 82.

2:50PM

As of 2:45PM a cluster of showers and thunderstorms has formed south and southwest of Boston, and is moving north northeast. This area will cross the Boston Area during the 3:00PM hour and into the Merrimack Valley and southern NH a bit later. Heavy downpours, isolated strong wind gusts, hail, and frequent lightning may occur with any of these storms.

Forecast Update…

FRIDAY: Partly sunny. Scattered showers and thunderstorms, some locally heavy. High 83-88. Wind SW 5-15 MPH with gusts to 20 MPH.

FRIDAY NIGHT: Variably cloudy with isolated showers and thunderstorms early, especially north and west of Boston, then partly cloudy. Patchy fog after midnight. Humid. Low 64-69. Wind light SW.

SATURDAY: Partly cloudy. Slight chance of isolated showers and thunderstorms again mainly north and west of Boston during the afternoon. High 81-86. Wind SW to W 5-15 MPH.

SATURDAY NIGHT: Partly cloudy. Low 65-70. Wind W 5-10 MPH.

SUNDAY: Partly cloudy. Scattered showers and thunderstorms mostly late. High 80-85. Wind SW 5-15 MPH.

MONDAY: Partly sunny. Scattered showers and thunderstorms mostly early. Low 68. High 82.

TUESDAY: Partly cloudy. Low 65. High 80.

WEDNESDAY: Mostly cloudy. Scattered showers and thunderstorms. Low 66. High 81.

THURSDAY: Partly sunny. Low 66. High 83.

3:52PM

There is nothing unusual about the weather pattern we are in, nor will there be, in the next week or so. It’s August, there will be weak fronts trying to move through but having trouble. It will be warm and often humid. There will be spotty showers and thunderstorms from time to time. A little drying may take place for part of next week if we can get a northern jet stream trough deep enough and progressive enough to pull some cooler/drier air out of Canada.

As I hinted at on some recent posts, I thought that some of the medium range models were overdoing the cool/wet pattern, making the troughs in the jet stream too strong for too long, and that starting around mid month we’d see a western Atlantic ridge of high pressure a little stronger than the models were forecasting at that time. This is and will continue to be the case. We’re not talking about a giant ridge of high pressure and super hot/muggy weather for the East, but a ridge strong enough to prevent major pushes of cool/dry air from Canada, as fronts have trouble pushing through cleanly, and tend to weaken and fall apart nearby. This will mean that there will be some episodes of scattered showers and thunderstorms, which is typical of August.

The other concern with a pattern like this is the tropics. They have been tending to get more active lately, and recent medium range computer guidance has been showing a tropical system that may make an approach to the eastern USA by later next week. Now, realistically it is far too soon to really be concerned about any one particular place, but the consistency of a tropical showing up on many different computer models just tells us we should be on the alert in the days ahead. Once a system is formed and starts to move along, we can start the process of prognosticating where it will eventually end up…

In the mean time, the next few updates of this blog will focus on the weather for the Boston Area, eastern MA, nearby southern NH, and northern RI. Have a great day and a great week everybody!

Forecast Update…

FRIDAY: Partly sunny. Isolated to scattered showers and thunderstorms mainly during the afternoon, with the greatest chance being the further west and north of Boston you go. Humid. High 80-85. Wind SW 5-15 MPH with gusts to 20 MPH.

FRIDAY NIGHT: Variably cloudy with isolated showers and thunderstorms early, especially north and west of Boston, then partly cloudy. Patchy fog after midnight. Humid. Low 64-69. Wind light SW.

SATURDAY: Partly cloudy. Slight chance of isolated showers and thunderstorms again mainly north and west of Boston during the afternoon. High 81-86. Wind SW to W 5-15 MPH.

SATURDAY NIGHT: Partly cloudy. Low 65-70. Wind W 5-10 MPH.

SUNDAY: Partly cloudy. High 80-85. Wind variable 5-15 MPH.

MONDAY: Mostly cloudy. Scattered showers and thunderstorms. Low 68. High 82.

TUESDAY: Partly cloudy. Low 65. High 80.

WEDNESDAY: Mostly cloudy. Scattered showers and thunderstorms. Low 66. High 81.

THURSDAY: Partly sunny. Low 66. High 83.