Good evening from Southern Connecticut Weather!

I know that SA mentioned our tracking of Hurricane Matthew yesterday, but a lot has changed down in the Caribbean. In an effort to give you the latest information and more importantly, attack the hype head on, I want to take a few minutes to update you on Matthew and what I'm thinking. 

The visible satellite loop of Matthew. Major hurricane Matthew continues to rapidly intensify, and is currently a powerful category four hurricane. It was a minimal hurricane yesterday at 5pm... 

Yesterday as SA was writing, Matthew was gradually strengthening in the Caribbean, in conditions that were favorable for development but not overwhelmingly so because of relatively strong wind shear. Overnight, Matthew developed an inner core, and as this forecaster watched live at 3am, began to undergo exceptional strengthening. 

That strengthening has continued all day, and currently Matthew is an incredibly dangerous storm with winds up to 150mph. In fact, Matthew continues to strengthen at this hour and has a real shot at getting close to category 5 strength. Interestingly, these winds are only confined to a small area of the storm--only the inner core, which is about 20 miles wide. 

If you like tropical development like me, this is a fascinating period. In the whole scheme of things however, this means relatively little for our region or sensible weather. Although Matthew is going bananas right now, there are checks on how strong these storms get--Matthew will probably undergo what is called an eyewall replacement cycle, a natural phenomenon with exceptionally strong hurricanes--these ERCs tend to blunt the strength of storms and I expect this to take place at some point. In fact, the National Hurricane Center (NHC) expects weakening due to changing conditions and eventual land interaction, though we'll have to watch. Intensity forecasts are inherently and infamously uncertain out in time.

A strong inner core is essential to rapid intensification, once Matthew developed a core last night it was bombs away...

The forecast: Track
​If anyone tells you that they know what Matthew will do after reaching after reaching the Bahamas, they're wrong. Here's what we know so far: I have relatively high confidence that Matthew will continue to move west to west-southwest, under the influence of high pressure. All of the guidance so far shows a turn to the north around the vicinity of Jamaica, as the storm feels a weakness in the ridge. Matthew, I expect, will be a potentially devastating storm to any land mass in the Caribbean, and by early Monday, the center will likely put Jamaica under the gun.

From there, Matthew is expected to continue on a generally northerly heading, most likely making landfall along the eastern Cuban coast later Monday into Tuesday, with the storm being weakened but off the coast of Cuba by Tuesday. From there, it is really anyone's guess of what happens. 

For us, the guidance has been all over the place. There are a couple of features that we're watching closely. I am posting a snapshot of a model run rather than my usual gif--just to highlight what we're watching. 

Ok--so what do we see above? This is a 500mb height and anomaly plot of the latest GFS about five days out. Much like winter, in order to know what's going on we have to look higher up into the atmosphere. The red shading and lines bending up are higher heights and ridging respectively. The blue shading and lines bending downward/closely represent lower heights and troughing. 

Forget about Matthew for a minute and follow the pieces on the board. First--look at the shading in the Atlantic due east of Matthew. This is the western Atlantic ridge. Broadly, the strength of this ridge will determine Matthew's path in the southeast. The second piece is over and north of our region. The strength and position of this piece will determine how quickly Matthew is kicked out to sea, if at all. The third piece is the blue shading, or troughing, in the midwest. The orientation and speed of this trough is one of the most important keys, as it may serve as the mechanism to kick Matthew out to sea well south of our region, or "capture" the system and draw it closer. 

It is impossible to know how these pieces will interact to impact Matthew's track right now.

8pm NHC forecast track. Note that the cone is not representative of uncertainty, it merely depicts the historical average of errors, which can be hundreds of miles the further out we are. At this point I favor an out to sea track despite any crazy models you see online, but this storm's long range track bears watching all along the coast. 

The Forecast: Intensity
I won't spend much time on this, but for our purposes, I will be focusing on how much Cuba disrupts the inner core of Matthew. Cuba has a number of high mountains, which could really disrupt a hurricane, but the guidance is almost unanimous in depicting a very intense storm once Matthew is in the Atlantic. This kind of consistency requires everyone along the east coast to take this storm seriously, even if it isn't at the ridiculous intensity it is at this hour. 

The Bottom line

• Major Hurricane Matthew is an exceptionally strong hurricane in the Caribbean, and additional strengthening is possible during this period of rapid intensification. 
• I expect there to be fluctuations in Matthew's strength once it reaches peak intensity, and weakening as it likely tracks over the mountainous area of Cuba.
• I expect a strong system to reach the Bahamas by early next week. 
• Any track forecast past the Bahamas at this point is highly uncertain, and it will be days until we better resolve the pieces that will determine what type of system will approach the US coast, if at all.
• As is normal during hurricane season, everyone should take the opportunity to check your preparedness plan, if you haven't already (and you should have!).
• This is a system to watch closely, but there is absolutely no reason to panic or lock in any type of impact on Connecticut. This system will have hype associated with it, but we are way too far out in time to do anything but watch.
  
  

Make no mistake, we're watching closely, but we are a long ways away from even taking the deterministic operational model runs seriously during the time period that would impact us. Don't get swept up in social media or the model runs. We'll be sure to provide you updates as we move forward. 

Please feel free to like, share, and spread the word to not believe any hype. The best way to follow a system like this...is one day at a time. You can follow us by clicking the buttons below and see our Facebook page or Twitter updates @SouthernCTWX. A note about tweets--I'll be retweeting a lot of information in the coming days. If you have questions, ask, but remember that even those tweets are snapshots in time. My information will be coming from reputable sources.

​-DB

​Good evening to you from Southern Connecticut Weather!
 
It’s been a decidedly fall-like week so far, with cool temperatures and cloudy weather the rule for most. The seasons have changed, and we are quickly moving towards the winter to come. We’re also finally getting some much needed rain, with more in the forecast for this weekend.  For the upcoming forecast period, generally normal to slightly below normal temperatures are expected, with rain and clouds being the prevailing conditions, before all eyes turn to Hurricane Matthew, currently tracking towards the Bahamas. For most of the forecast period, global guidance is in excellent agreement, so took a consensus blend for the daily forecasts.
 
Friday-Sunday
 
A cutoff low has been to our west for most of the week, bringing substantial rain to western NY, PA, and further south. That low will finally move east tomorrow into the weekend, bringing much needed rain to the area. I don’t expect a total washout over the weekend, rather, scattered to numerous showers look likely, with the highest chances for showers on Saturday. When you combine the showers with the low clouds, fog, and cool temperatures, it may be a wise idea to plan indoor activities for the weekend. If you’re itching to be outside, Sunday looks like the best day of the three, with breaks in the showers likely and maybe even some partial clearing in western areas. Temps will continue to run below normal, with highs around 60 expected all three days. Total rainfall will vary depending on location and shower placement, but generally, I expect between half an inch to an inch of rain across the state, with the best chance of an inch being in the eastern portions of the state.
 
Here’s total rainfall from the GFS, as well as simulated radar from the NAM for Saturday morning.

Monday-Tuesday
 
Some showers could linger into Monday, especially in eastern areas. Otherwise, expect cool and cloudy conditions to continue, with highs only reaching the low to mid 60s, warmest in the SW corner of the state. We could see some pockets of clearing on Tuesday, but they will likely be far and few between.
 
Wednesday
 
GFS and Euro differ here, with the former keeping us under the clouds while the latter lifts the deck out to our north and brings us some sunshine at last. For now, will split the difference and go for a partly cloudy forecast. Temps around normal in the mid 60s.
 
Late next week
 
It’s been another quiet hurricane season in the east, with very few storms of note so far. So, several days ago, when the GFS showed what is now Hurricane Matthew hitting the northeast late next week, weather enthusiasts everywhere took note. Over the past couple of days, we’ve seen a range of solutions on the guidance, ranging from a direct hit, to a glancing blow, to a complete miss out to sea. Several factors influence the eventual track of the storm. The first is when it turns to the north; right now the system is running almost due west and it is forecast to turn north over the weekend. If it can “thread the needle” between the Caribbean islands and travel through open water, the storm will remain stronger than if it travels over land. Secondly, the guidance has recently begun to key in on the development of a kicker in the northern stream, which would be arriving on the eastern seaboard around the same time as Matthew. The kicker would serve to “push” the storm further east, resulting in a track out to sea. And the third factor, perhaps the most important, is time.
 
We are still eight to nine days out(at the minimum, the Euro has the storm still well south of us at day 10, the end of its run) from a potential impact to the area, and as regular readers will know, that is an eternity in weather land. At this range, the only thing we can really take from the models is the idea that there will likely be a large storm somewhere on the eastern seaboard towards the end of next week; where it will end up and who it will impact will remain unclear until we move closer to the event and can get more accurate data. National Hurricane Center recon flights are going out tonight which will likely put more accurate data into the modeling, but for me to become more confident in some sort of impact, I’d want to see a uniform consensus of a hit last through the weekend on the guidance.
 
We’ll continue to keep a close eye on Matthew, and will have more information for you in our next discussion on Sunday. To illustrate the inconsistencies and swings in modeling at this range, here is a comparison of the 12z and 18z GFS for 8 AM next Friday. Notice that one has a large hurricane over the area, while one has it so far out to sea that the low center isn’t even visible in the image. ​The lesson to be learned from these images is that at this lead time, nailing down any sort of track is impossible, and the general theme of a storm somewhere in the area is all we can realistically look for.

Have a great weekend and thank you for reading SCW!
​-SA

Disc: One of the terms a forecaster hates to hear is "cutoff low".  A cutoff low is a low pressure system that is "cut off" from the main flow, and as such, doesn't move very much.  We'll have to deal with one of those this week- a little more on that later.

On the current weather map, a cold front has cleared the area, and now stretches from VA to near Nantucket.  We can already see the next players on the field, as the front is going stationary south of the Mason-Dixon line, and an upper level low is centered over Lake Superior.  These players will all play a role in the weather this week across the state.  Also noted on the upper air charts was a strong block over Southern Canada, which will also play a big role in our weather.

First of all, for tonight, fair weather.  Although clouds will be on the increase, not expecting any precipitation.  Temperatures will range from 50 to 60.

Tomorrow: As weak low pressure begins to organize along the stationary front, a stiff Northeasterly wind will develop.  This, combined with cloudy skies, will keep temperatures cooler than today.  Precipitation chances will be low, but not nil, as there could be a sprinkle at any time, especially from noon on.  I don't like the idea of coastal drizzle, since winds will be NE, but sprinkles will be a possibility.  High temperatures should be in the mid to upper 60s.

Tomorrow night and Thursday: Much of the forecast beyond tomorrow afternoon depends on how the cutoff low evolves.  Right now, most of the models keep the majority of the precipitation associated with this low further south and west than before, which would mean SW CT could see a decent soaking, while NE CT would not see a whole lot of rain, but would still be very cloudy, cool, windy, with periods of light rain.  However, I need to point this out, because it's important for the public to know, that forecasting cutoff type lows is never a certainty.  We have seen many times where models come to a consensus forecasting the axis of heaviest precipitation to be in a certain spot and then it turns out to be in a totally different area, even as close in as 12 hours out.  Recent examples of this include Hermine and "Juno" the Jan 25, 2015 fiasco.  A more distant example for some veteran forecasters is March, 2001.  So, as always, stay tuned for updates, and I will try to pinpoint the best possible forecast that I can.  It's just important to know that these are probably the single most difficult systems to forecast and many times, changes occur at the last minute.  Anyway, for tomorrow night, for now, not expecting much rain for most of the state, but there could be a rogue shower in the SW.  For Thursday, rain should arrive during the afternoon and propagate from SW to NE.  As for temperatures, expect chilly weather, with lows in the mid and upper 50s, and highs 60 to 65.

In the longer term, for Friday, expect periods of rain, with wind gusts of around 40 MPH and an all-around raw day.  It's hard to pinpoint when and where the heaviest rain will set up.  It may not rain in the entire state at every minute, but most of the day will be rainy.  High temperatures should be pretty uniform and chilly- 60 to 65 throughout the state.

For the weekend, questions only get larger, as one would expect, heading into the longer term.  The two main questions are how long this cutoff low hangs around and then whether this same system can spawn another coastal low, as well.  Chances of that happening are relatively low, but nothing can be ruled out.  For now, the best weekend outlook that I can come up with would be for Saturday would be relatively ugly and Sunday would be the best of the two days.  For Saturday, expect rain on and off much of the time.  Once again, as I said for Friday, there will be difficulty pinpointing when and where exactly the heaviest rains will fall.  But don't expect nice weather Saturday.  Temperatures should be in the upper 60s.  Sunday could see some sun, but there is still the chance of a shower, especially later in the day or evening, since the upper level low will still be hanging around.  Highs should again be in the upper 60s.

Looking further out, next week should see the chance for another more solid area of rain on Monday, as the upper level low finally swings through on its way out.  Then for Tuesday, the weather should finally clear out, at least for a while.  Expect highs near 70 Monday and in the upper 60s on Tuesday.

Thereafter, all eyes turn to the tropics.  A tropical wave, currently east of Barbados will soon be a named tropical cyclone and be moving west through the low latitudes.  Given the position of the Western Atlantic Ridge and the block over Canada (which will still be in place), there is the *POTENTIAL* for this storm to come up the coast.  Whether it moves up parallel to the coast, moves at  a latitude too far east for many effects, swings west like Sandy did, or even makes landfall in the Gulf of Mexico and tracks northward after that, west of the area, are all options right now, but looking at the positioning of various features in that time frame does signal the potential for an east coast tropical system.

Let's take a graphical look at some of the systems slated to affect the area, starting with this cutoff low.  Here's a map valid Friday morning.  (It's just a sample time I took that seems to be during the "core" of the storm- at least for now).  You can see at that moment there is a good slug of rain across SW CT and adjacent LI and upstate NY.

Now I want to do something a little different, and post an upper level long range map, but I want to show the blocking that will be in place for any potential tropical system at that time frame.  This map is the CPC average map, which is an average of all long range guidance.

​

You can see the very strong block centered over the Canadian Maritimes.  When a block like that esets up, usually some type of stormy weather results.  That's all for now! Enjoy the rest of your week (perhaps spent inside reading books or watching movies)!

-GP!

Happy fall from Southern Connecticut Weather!

GFS depiction of 850mb temperatures this morning. Are those below freezing 850 temps in northern New England! It's starting to feel like fall around here, with sunny skies and temperatures in the 50s across the state! A gorgeous day is on tap, with high pressure dominating and northernly flow. Temperatures will struggle to make it into the 60s in our colder spots, but most will see temperatures eventually climb into the mid to upper 60s. Get outside and enjoy it!

Visible satellite from this morning. Notice the fog developing and burning off this morning in the valleys out west!

When I was thinking of how my forecast would look the other day, I thought it would be another easy one, with only one rain event. However, things this morning look a little more complicated than before. I think this forecast has a little something for everyone—cool temps, sunny days, and rain chances. Let’s dive in. 

Monday
Tomorrow looks like a carbon copy of today—with a colder start. I expect the cold spots in Connecticut to get down into the mid to upper 30s. Urban areas will even get to the low 40s. With temperatures like that, folks should be prepared for frost in our cold spots. A Frost Advisory will be in effect overnight in Litchfield County. I anticipate a widespread frost there and patchy frost elsewhere. Be prepared to protect your plants and gardens. Monday is great day, with high pressure remaining in control through the daylight hours. By evening however, clouds start to overspread the state, in advance of a cold front. 

Tuesday
Tuesday is our high confidence rainy day. Now, the guidance has been wobbly on how significant a rain event this is, but I think we see a decent event, with the cold front/attendant low tapping into some Atlantic moisture. Tuesday is an umbrella day, and while it may not always rain on Tuesday, rain that falls could be heavy at times. Right now, I am expecting a solid half inch to inch of rain across the state. 

The guidance is a bit split on when the rain cuts off, but right now I lean toward a faster end, with showers exiting the region by late Tuesday night.

06z GFS depiction from early Tuesday morning into early Wednesday. 

The GFS shows a rainy Tuesday as the front pushes through, but the frontal passage goes far enough off shore to prevent lingering showers on Wednesday. 

Wednesday/Thursday
Assuming that my forecast is right and the front is well offshore, Wednesday looks great as sunny skies and seasonable temperatures return. I am less confident than usual, because the guidance is in decent agreement that a cut-off low will likely develop. These lows are generally slow moving systems that meander as they get left behind by the overall flow that moves systems in and out of our region. Typical in spring, these can bring cloudy, cool, and rainy days. Here, I’m looking to see how close the low gets to us. If it is closer, expect a cloudy and potentially wet Wednesday/Thursday. 
​
Right now, I think both days are ok. As I said before, Wednesday is probably great. Thursday looks a bit more cloudy with a greater potential for rain, but right now I think it’s mostly dry. Greg will have much more on this Tuesday. 

Friday/Saturday
Right now, I lean toward a wet Friday, as an offshore low gets close enough to bring precipitation. This is a low confidence forecast, unfortunately, and it lasts into early Saturday, as the low could linger a bit. The weekend does look nice, as any low moves away early Saturday, but this is something to keep an eye on.

That same 06z GFS run showing the possibility of an area of low pressure bringing showers Thursday through very early Saturday. Not quite biting on it yet, but it is something to watch. 

Foliage Update
How about a fall foliage update! Foliage is something I like tracking during autumn, and the season is off to a muted start due to the current drought. I’m not sure how good a season it will be, but at least we can track the color change. Thanks to The Foliage Network we can see the changes in color and leaf drop during the fall. Right now, there isn’t much change happening in Connecticut, but higher elevations in central/northern New England are already seeing some change. With warm days and cool nights this week, I expect a nice expansion of color change to happen by next week. 

Image courtesy of The Foliage Network. Follow them here!

The dailies
Today: As close to perfect as it gets. Sunny and seasonably cool with highs in the mid to upper 60s in much of the state. Low 60s in the hill towns. Lows in the mid 30s in cold spots to low 40s in urban areas. Widespread frost expected in Litchfield County. Patchy frost expected elsewhere.

Monday: Sunny and seasonably cool. Highs in the mid to upper 60s. Clouds developing late. 

Tuesday: Rainy and breezy. Highs in the upper 60s to low 70s. Chance of rain 90%. 

Wednesday: Slight chance of showers early, otherwise, sunny and dry. Highs in the upper 60s to low 70s. Chance of rain 10%.

Thursday: Partly to mostly cloudy with a chance of showers late. Highs in the upper 60s to low 70s. Chance of rain 20%. 

Friday: Mostly cloudy with a chance of rain. Highs in the mid to upper 60s. Chance of rain 40% 

Saturday: Mostly cloudy early with a slight chance of showers, sunny by afternoon. Highs in the upper 60s. Chance of rain 10%

Sunday: Sunny and dry. Highs in the mid to upper 60s. 
 
Thank you for reading. Enjoy the last week of September!

​-DB 

For those tired of heat and yearning for nice fall weather, you'll get your wish, but you have to make it through this work week first.

On the current weather map, the region lies in a squeeze play between two pressure systems.  It is not windy, however, as one might expect, given that both pressure systems are weak and the pressure gradient is only 9 MB.  Weak high pressure, which has the majority of control of our weather, was located over the Appalachians, while weak low pressure, associated with the remnants of Julia, was located over the Outer Banks of NC.  This was also located along a cold front, which is undergoing frontolysis, or the death of a front.  This front extended from the Outer Banks of NC, to the Delmarva, to Montauk Point to Cape Cod.  The mid and high clouds across the area today are from the remnants of Julia.

For tonight, with cloudy skies and a rather humid air mass in place, temperatures will not get very cold.  Expect lows to be from the upper 50s to the mid 60s.  

For tomorrow, METAR obs will likely report cloudy all day, but we'll still see good amounts of sun.  This is because clouds will tend to thin out as the day wears on, but there still will be a high cloud canopy.  But most people will not think of tomorrow as a cloudy day.  High temperatures should be mostly in the low 80s, but the NW hills could stay in the upper 70s.

For tomorrow night and Thursday, the last of the high clouds will depart tomorrow night from north to south.  Since the clouds will be slow to depart, low temperatures will show a very large range from north to south, since the north country will be able to radiate and much of the south coast will only have a few hours, toward dawn, to radiate. Low temperatures could get as low as near 50 in the north, but stay in the low 60s along the south coast.  On Thursday, although it is the first day of fall, temperatures will rise to levels more common in the summer.  High temperatures should be 80 to 85 across the state, with even a few upper 80s possible in the CT valley!

Longer Term: A strong cold front, a front which will usher in the first true autumn air mass, will move through on Friday.  Although this front does not have copious amounts of moisture to work with, I feel pretty confident that most locations should see a quick shower with the frontal passage.  There are a few reasons for this.  First, the front will be moving into a very warm air mass.  Secondly, temperatures will really crash with the frontal passage.  Finally, since cold air usually sinks from the top down, the upper levels will cool first.  This will create very high lapse rates.  The lapse rate is the rate at which the temperature cools as you rise.  Typically, the temperature will cool about 6 degrees for every 1,000 feet of height rise.  With a strong cold front like the one moving through Friday, these lapse rates will be higher than normal, as the upper levels cool faster than the lower levels.  The higher the lapse rate, the greater the instability.  Surface-based models often have a hard time picking up on this and underdo the amount of convection that can form in that type of setup.  Also keep in mind, the air does not have to be saturated to get convection to form in a situation like that.  We're not looking at flooding rains, just quick hitting cells.  If everything panned out just right, it wouldn't even surprise me to see small hail with stronger cells, since the freezing level will be lower  than normal, but I'll leave that out of the forecast for now.  As for temperatures on Friday, expect highs in the 75 to 80 degree range, with some lower 80s in the CT valley.

The first weekend of fall will feel like the first weekend of fall.  The rest of the extended period should be dry.  So instead of going into a long discussion about each day, let's just look at temperatures and brief weather conditions for the rest of the extended.

Saturday could start out with a few clouds in SE CT, so expect lows 50 to 60, with a few low 60s down there.  Highs should be 65 to 70, with some low 70s in the typically warmer CT Valley.

Sunday should see lows in the 40s, with a few 30s possible the NW Hills! Highs on Sunday should be only 60 to 65, with a few upper 60s in the CT valley.  Get the jackets ready!

Monday should see the same lows as Sunday, with highs 65 to 70, except a few low 60s in the NW Hills.

Tuesday should see lows in the low 40s to low 50s, with highs 65 to 70.

A reinforcing shot of cold air moves through late Monday night into early Tuesday morning.  There could be a few sprinkles associated with that.  Once again, moisture is lacking and timing is not great.

Looking out further, behind the secondary cold front Wednesday to Thursday could see an even stronger shot of cold air than the one for this weekend.  Beyond that, the pattern could moderate and we could see an extended period of temperatures averaging a bit above normal.  But climatological normals lower with time and slightly above normal heading into October will feel chilly compared to what we have been experiencing!

Here is a look at some of the weather that will be affecting the state this upcoming week.   Since we don't have many precipitation-making events to speak about, I'll post a map showing Friday's frontal passage, then we'll look at Sunday morning's lows.  Here's a look at the frontal passage for Friday afternoon: 

You can see the showers affecting W CT, and getting ready to move ESE into much of the rest of CT.  Also note the first true Arctic high of the season north of Lake Superior bringing cool air down!

Now, here's a look at the GFS' predicted low temperatures for Sunday morning.  Low temperatures are actually about 2 degrees cooler than what is shown on this map.  You can see the dark green (30s) covering W MA.  Another 2 degrees cooler (achieved an hour or two earlier) would bring some of those 30s into W CT.

That's all for now! Have a great rest of your week!
​-GP!