My how time passes. The first third of 2016 has come and gone, and we are heading into May, the last month of meteorological spring. Pool openings, Memorial Day, and summer are right around the corner! 

Another season is arriving, however—Severe Weather Season. This post will give you the basics of thunderstorm development, severe weather climatology in Connecticut, and what we should expect this season. Sit back, grab some snacks, and enjoy the post! Share with friends and family and refer to this guide during severe season!

Overview
Do you remember the incredibly impressive severe weather outbreak on February 24th? Severe weather can happen at anytime if you have the necessary ingredients. Generally though, I consider May through September to be severe weather season. The peak of the season is usually June and July. 

Why is May the start of severe weather season in Connecticut? Let’s take a look at climatology to see why. 

May Climatology
Hartford (BDL)
Average May 1 High: 67
Average May 1 Low: 43

Average May 31 High: 75
Average May 31 Low: 52

Bridgeport (BDL)
Average May 1 High: 63
Average May 1 Low: 46

Average May 31 High: 72
Average May 31 Low: 56

​Usually, at some point in May we begin breaking toward more of a summer like regime. This provides early opportunities for the ingredients of thunderstorms to come together. With warmer temps, conditions become more favorable for the development of convection—the vertical transport of heat and moisture in the atmosphere, especially through updrafts and downdrafts in an unstable atmosphere. It is important to note that often, the terms "convection" and "thunderstorms" are used interchangeably, but thunderstorms are only one form of convection. The vertical transport of heat and moisture is critical to “boomer” formation.​

Have you ever seen a cumulus tower? Of course you have, even if you don't know it! CU towers are an example of convection at play and is often a precursor to a summertime rain shower or thunderstorm!

Ingredients for Thunderstorms and Severe Weather
Ok, so what do we need for thunderstorm formation? Essentially, you need three things: Moisture, Instability, and Lift. For severe weather, add a fourth, wind shear.

Moisture
Think of a hazy, hot, and humid summer day. If you asked people what they remember about the end of those days, many will answer that they remember the thunderstorms. Moisture is a key element in thunderstorm development. Without moisture, you’re not going to have precipitation!

What to watch for: if you want to know what kind of moisture we’re dealing with during this time of year, look at the dewpoint—which is a measure of atmospheric moisture. A dew point is the temperature to which air must be cooled (generally) in order to reach saturation. The higher the dewpoint, the more moisture in the air.

During the summer, dewpoint is directly related to how humid it is. On a 90 degree day, a 70 degree dewpoint is not something most people what to see.

If you like boomers however, you want a whole lot of heat and a whole lot of humidity. Having that much moisture and heating leads us to our next ingredient…

Instability
Instability is another critical element of thunderstorm production, and the more instability there is, the more potential you add to a developing storm. 

Instability—is the tendency for air parcels to accelerate when they are displaced from their original position, especially upward after being lifted. You don’t need a lot of instability for a garden variety boomer, but you need Instability and lots of it for for severe weather.

An unstable air mass is usually characterized by warm moist air near the surface and cold dry air aloft. This allows air that is forced upward to continue to rise on its own, which eventually will cool and develop the clouds and precip that make up a thunderstorm. High instability also contributes to prolific lightning events, which isn’t characterized as severe weather by the NWS but is deadly in its own right.

What to watch for: Convective Available Potential Energy, or CAPE—is a measure of the energy available for convection. CAPE is directly related to the maximum potential vertical speed within an updraft. 

As the National Weather Service notes, observed values in thunderstorm environments often exceed 1000 joules per kilogram (J/kg), and in extreme cases may exceed 5000 J/kg. Now, 5k CAPE around here is unheard of, but If we’re talking about a high CAPE day, your ears should perk up. 

There are various measures of CAPE out there, including surface based CAPE (SBCAPE), mixed layer or mean layer CAPE (MLCAPE), most unstable or maximum usable CAPE (MUCAPE), and normalized CAPE (NCAPE). SBCAPE is important in my book, and that is usually the first place I look before looking at other parameters.

Lift 
Lift is our third ingredient for thunderstorm development. You can have moisture and instability, but if you don’t have lift, not much is going to happen. Lift provides the air the nudge it needs to rise and form convection. It happens a number of ways around the country, but in this region, we’re usually looking one major mechanism. ​

The most common mechanism around here for thunderstorm initiation is the ole’ (cold) front. Fronts are the boundary between two air masses of different temperatures and air densities. When the cold front rolls through, the colder and more dense air behind the front lifts warmer and less dense air abruptly. When all the ingredients are together in the right quantities, you have showers and thunderstorms. 

A vertical diagram of how lift works along a front. 

The Fourth Ingredient: Shear
In order to get a severe weather day, we need some sort of shear. You can have a high CAPE/low shear or high shear/low CAPE day, but you need shear for severe weather. 

Shear—is the change in wind speed (speed shear) and/or direction (directional shear)  with height in the atmosphere. Shear usually refers to vertical wind shear.

Speed and directional shear is important in severe thunderstorm development. With speed shear, a significant increase of wind with height will tilt a storm’s updraft. This allows an updraft and downdraft to occur in separate regions of the storm and reduces the risk of water loading and thunderstorm collapse. 

Directional shear helps initiate the development of a rotating updraft. This is key in the formation of a supercell—the most mature and dangerous type of thunderstorm. Supercells are thunderstorms consisting of one quasi-steady to rotating updraft (I.E. storm with rotation). These are the storms most likely to produce large hail, strong winds, and tornadoes.

What to watch for: areas of low pressure, especially tropical systems upper level lows, can bring high shear days. 
​
The Great Wildcard: The Elevated Mixed Layer
Elevated Mixed Layers, or EMLs are relatively rare in New England. With the right ingredients however, EMLs can bring the biggest of New England severe weather outbreaks. ​

EMLs can travel long distances and provide a “cap” that allows for high to extreme instability to develop. By itself, like all the other ingredients for severe, an EML doesn’t create severe weather, but when an EML is in the mix, watch out.

Excellent diagram of how EMLs work. Although this is focused on the midwest, EMLs operate similarly in this region, especially with regard to creating high to extreme instability environments. Image courtesy of Missouri/S Illinois Weather Center.

How a Thunderstorm Develops
Ok, so we’ve gone over the big ingredients for thunderstorm development. Well, how in the world does all of that come together for the storms we see every summer?

Most thunderstorms develop and die in three stages. These stages are: the development stage—when you see the cumulus towers form; the mature stage—where the storm is fully formed and does its damage; and the dissipating stage—when storms weaken and die.

The circle of life for thunderstorms.

The Development Stage
It begins when warm and moist air is lifted upward. This is the updraft that often creates our cumulus clouds and towers. The moisture in the air condenses into water droplets as it rises into a cooler environment. The cloud will continue to grow in height as long as warm air from below continues to rise.
As mentioned before, there are several ways that an updraft of warm and moist air can form.  Fronts are typically the best mechanism, but often times, updrafts form without any guidance because warm air naturally tends to rise. Air near the ground heats up during the day as energy from the Sun heats the ground, which then heats the air. Because warm air has less density than cool air, the warmer air rises higher in the atmosphere.

The Mature Stage
As the cumulus cloud continues to grow, the water droplets within it grow larger as additional moisture from rising air is added to the droplets. The cloud will begin to look darker as more water is added to it. This process adds weight to the droplets, and raindrops will start to fall through the cloud when the rising air can no longer hold them up. For hail production, the updraft is so strong that the water droplets freeze in the higher column of the storm until the updraft cannot support the hailstone. At the same time, cool and dry air flows downward in the cloud, called a downdraft, pulling water downward as rain. With an updraft, downdraft, and rain, the cloud is now called a cumulonimbus cloud and the cycling of air up and down is called a thunderstorm cell. In this stage, the intense updraft and addition of shear can create a supercell, which is mesoscale cyclone (storm with rotation) that drops tornadoes, hail, and very strong winds.​

The moving air within the cloud builds up electric charges as it slides past other air. This allows lightning to form, similar to the classic example of creating a spark after moving your feet across a carpet. Thunder is the sound that happens when lightning strikes, and happens after you see the bolt of lightning because sound travels more slowly than light. Lightning can strike many miles away from an actual rain shaft or thunderstorm cloud. When thunder roars, head indoors. 

This image shows a cross section of a hail producing thunderstorm. 

The Dissipating Stage
When the downdrafts in the cloud become stronger than the updraft, the storm starts to weaken. Since warm moist air can no longer rise, cloud droplets can no longer form. The storm dies out with light rain as the cloud disappears from bottom to top. The whole process takes about one hour for an ordinary thunderstorm. Severe thunderstorms and squall lines are much larger, more powerful, and can last for several hours.

This incredible image taken from space is undoubtably of a supercell, complete with an anvil spreading clouds out over dozens of miles and an overshooting top!

Severe Weather in Connecticut

A NWS map of all severe weather reports in 2015. 

Allow me to be Captain Obvious for a second: Connecticut is not Oklahoma. The major threats we face here are not EF-5 tornadoes, but rather large hail and strong winds. Unlike synoptic or large scale events like snowstorms, severe weather is inherently local, with isolated areas getting legitimate severe weather and places just a few miles away a lot of sound but not much fury. For property owners this is a good thing, generally, if you are on the right side of a supercell. For forecasters though, this is a nightmare, as predicting mesoscale (small scale) details far in advance is next to impossible. 

Widespread severe weather outbreaks, especially in New England, are relatively rare. There are two reasons for this.

The first is the definition of a severe thunderstorm, which is a high standard to meet:
A Severe Thunderstorm is defined as a thunderstorm that produces wind gusts of at least 58 mph and/or hail 1 inch in diameter (quarter size) or larger. Any thunderstorm that produces a tornado (or waterspout) is a severe thunderstorm, but those are warned differently.
​
The second reason is location: 
New England is located in a more stable (generally) environment. The ingredients and mechanisms that produce severe thunderstorms do not align here very often, and when they do, the parameters that create big outbreaks (high CAPE/high shear) are often on the lower end of the severe scale than in the midwest. This results in generally weaker events, but that does not mean CT cannot see high end severe weather events. 

Connecticut is actually an interesting space when it comes to severe weather, in particular, tornado climatology. 

The above image is national climo for tornadoes per year. The bottom image is the history of CT tornadoes. Images courtesy of the NWS and Wikipedia (of all places). 

With complex mountainous and valley terrain and the presence of boundaries (think lift) that form commonly along Long Island Sound, CT seems to be in a location that is more vulnerable than most to tornadoes in New England. 

That said, wind and hail are the bigger severe producers around here. Wind is the most common severe weather report. Straight line winds can be as powerful as hurricane force winds!

Let’s take a look at how we define our watches and warnings.

-A Severe Thunderstorm Watch is issued by the Storm Prediction Center (SPC) in Norman, Oklahoma for large portions of the region when the potential exists for severe thunderstorms. 

-A Severe Thunderstorm Warning is issued by the local National Weather Service Forecast Office when severe thunderstorms are imminent based on radar or already occurring based on spotter observations.

-A Tornado Watch is issued by the Storm Prediction Center in Norman, Oklahoma for large portions of the region when the potential exists for tornadoes. 
​
-A Tornado Warning is issued by the local National Weather Service Forecast Office when a tornado is imminent/occurring based on radar or already occurring based on spotter observations.​

Finally, it is important to know what the SPC outlook is. This is an outlook that extends from day 1 into the longer range to give individuals a sense of what to expect in each region with regard to severe weather. 

What to Expect This Severe Season

SPC probabilities of any severe during the year. Note that the peak for our region is June and July--the height of summer, and that a sharp drop off traditionally happens during August and into September. 

The last severe season had a few notable events, but overall it was a quiet one. This year, I expect a more active season as we transition from El Nino to La Nina. I think we have a decent shot at a warmer than normal summer, and with it (and other factors), the chances of severe weather. 

Severe Season Preparedness
Finally, I want to spend some time on how to prepare for severe weather season. Much of this information comes straight from the National Weather Service. 

-If you don't have one already, a NOAA Weather Radio is a great investment for overnight hours. With warning alarm tones, a weather radio will alert you when severe weather headlines are issued, providing you time to bring in furniture and prepare if you are in a place that usually loses power. 

Lifeguards at beaches and pools have devices that can track thunderstorms and lightning. The same is true for athletic coaches, camp directors, and parks and recreation workers. Even without equipment, you can protect yourself by moving indoors to a place of safety at the first rumble of thunder. If you can hear the thunder, the storm is usually close enough for you to have the potential to be struck by lightning.

Lightning is an underrated killer. Lightning also leaves many victims with life-long serious injuries. Lightning can strike as far as 10 miles from the side of the thunderstorm cloud. In fact, many lightning victims are struck before the rain arrives or after the rain has ended and the storm is moving away. Most victims also report that at least a portion of the sky was blue when they were struck.

While inside a home or building
-Avoid any contact with corded phones.

-Avoid any contact with electrical or electronic equipment or cords that are plugged into the electrical system.

-Avoid any contact with the plumbing system. Do not wash your hands, do not wash the dishes, do not take a shower, or do not do laundry.

-Do not stand next to a concrete wall and do not lie on a concrete floor.

-Stay away from windows, outside doorways, and porches.

Tips while outdoors
-Watch for falling debris while driving.

-Plan outside activities so that you minimize the risk of being caught outside in a thunderstorm.

-If you hear thunder, move inside a safe shelter immediately. Generally, if you can hear the thunder, you're within striking distance of the storm. Golf courses, beaches, and pools are places where there are higher concentrations of injuries.

-If the sky looks threatening, move inside immediately. Don't wait for the first stroke of lightning. It could occur anywhere under or near the storm.

-Stay inside a safe shelter for at least 30 minutes after the last rumble of thunder was heard. Many lightning victims are struck after the worst part of the storm has passed.

-If you are caught outside in a thunderstorm and can't reach a safe shelter, you can only minimize your risk of being struck by lightning. If lightning strikes near you, it will most likely strike the tallest object in your immediate vicinity. Don't be the tallest object in the immediate vicinity and don't be near the tallest object. Second, get as low as possible to the ground, but minimize your contact with the ground. Do not lie on the ground.

This was a long post, but we're only touching the tip of the iceberg of what makes severe weather happen. Hopefully this will be something you can refer to during severe weather season. Rest assured, SCW will be here on Facebook and Twitter @SouthernCTWX to track storms and help you plan ahead. Please like, share, comment and ask questions. That's what we're here for!

-DB

Good afternoon and happy Saturday from Southern Connecticut Weather!

Today we’re providing you with a special double edition of SCW. This post will cover the week ahead, and the next post covers May climatology, the basics of severe weather, and severe weather in Connecticut. It will be a must read!

As a result, this will be a relatively quick post. After a period of very nice weather earlier this month, New England has reverted to cool, dark, and damp, as a trough battles for control over our region. This pattern looks to continue into the foreseeable future, with multiple rain and shower chances through the first week of May. 

Saturday
Today is the pick of the weekend. Partly cloudy skies will dominate as high pressure sits overhead, and temperatures will be nice and comfortable in the mid to upper 60s. Get out and enjoy it. This is probably the best day you’ll see weather wise the entire forecast period.

Current visible satellite loop of clouds over CT. Go enjoy while you can!

Sunday/Monday
Sunday is the first of the rainy days in this forecast period. Low pressure out west will send precipitation our way, and although it is unlikely we rain all day, it will be a raw, wet, and cold day with easterly winds that keep temperatures in the upper 40s to low 50s. Not a great day for activities. 
​
Latest data suggests that the morning hours should be fine for activities, but the afternoon and evening hours don’t look great.

GFS showing the period between Sunday 1am and Monday 1am. The afternoon looks wet for sure, but I don’t think it is a total washout.

Monday is another wet day, but should be more showery than rainy as a warm front makes its way north. As a result, we likely get back to warmer temperatures, but shower chances remain.

Tuesday/Wednesday
Tuesday looks like the dry day of the week with low pressure departing, but Wednesday at this time looks like another day with the chance of showers as another system passes to our north and the attendant front makes an approach. 

Thursday/Friday
The end of the weeks looks wet again as the dreaded cutoff low looks to setup somewhere in our vicinity. Neither day looks like a washout at this point, but there is potential. The european model in particular shows a strong coastal low making a run at the region Thursday night into Friday, but, like we said during the winter, one model run does not make a forecast. ​

Overall, we remain unsettled heading into the first week of May. With a trough developing over the region, a fast break toward more late spring weather and temperatures is off the table.

Euro ensembles showing a strong trough developing by the end of the week. Below is the EPS projection of 850mb temperatures. Expect cool and unsettled weather. 

The dailies
Saturday: Partly sunny and nice! Highs in the mid to upper 60s. 

Sunday: Mostly cloudy skies in the morning with rain beginning by noon. Rain off and on during the afternoon and evening. Seasonably cold. Highs in the upper 40s to low 50s. Chance of rain 90%

Monday: Chance of showers early, tapering off by noon. Otherwise, mostly cloudy. Highs in the mid to upper 50s. Chance of rain 70% early. 

Tuesday: Partly cloudy and warmer. Highs in the mid 60s. 

Wednesday: Partly cloudy with a slight chance of showers in the afternoon. Highs in the mid to upper 60s. Chance of rain 20%.

Thursday: Cloudy with a chance of showers. Highs in the mid 60s. Chance of rain 50%

​Friday: Cloudy with a chance of showers. Highs in the mid 60s. Chance of rain 50%

Thanks for reading SCW and don’t forget to read the second edition on severe weather!

​-DB

It was inevitable.  Spring in New England has the lion's share of gloomy, chilly weather.  This spring so far has not really had any of that.  Sure, we've had cool weather at times, but the cool weather has been sunny and dry, not rainy and gloomy.  The pattern we are about to enter will feature a lot of the gloomy. cool weather. (No it isn't going to rain every day).

Starting with tonight, skies should gradually clear, as cold high pressure over Southeastern Canada builds in- a position more typical with mid-winter.  Temperatures will be a bit tricky, because low-level clouds may hang around longer than forecast.  This would keep temperatures higher, but given the air mass about to enter, any areas that clear certainly have frost, and maybe even freeze concerns.  For now, I'll forecast low temperatures to range from near 30 in the cold spots to near 40 along the south coast.  For those who live in the colder areas, I'd recommend covering up or bringing inside any delicate plants.

For tomorrow, it will be sunny, but a bit chilly for the time of year.  High pressure will be in control, so we won't have to worry about any adverse weather conditions.  Even with the cool air mass in place, the sun is strong this time of year, so temperatures will approach, but probably come up a few degrees short of 60 in most places.  A sea breeze may develop, producing even cooler temperatures in the Southeast.

For tomorrow night and Thursday, the next system will have to be watched.  This is a coastal low.  Like most coastal lows in the winter, we're not sure on the exact track of it right now, and this will determine where the heavier precipitation is.  Temperatures will also be determined by who gets heavier precip.  Right now, it seems like the south coast has the best chance of getting into heavier precipitation.  Another fly in the ointment is timing.  If the rain waits until later to arrive, and some sun breaks through, temperatures on Thursday will be warmer than currently forecast.  For now, a good compromise would be to leave Thursday's temps very similar to those of Wednesday.  Working backwards for a second, Thursday morning's lows should range 30-35 in the colder locations to near 40 along the south coast.  As far as timing this event, the best chances for any rainfall would be from late in the afternoon on Thursday through Friday morning.  (There is still a distinct possibility that this low goes further south and no rain falls in the state at all, and if it tracks further west, rain could linger longer into Friday).

Looking into the longer term, Friday will once again be determined by the fate of the coastal low.  At this point, since the forecast is a brush, we'll assume that any rain pulls out by dawn, but this could definitely change in future shifts.  Even if this happens, Friday will be a chilly day, with cooler temperatures along the south coast, due to clouds from the coastal low, and warmer temperatures further north. Highs should range from the 50-55 degree range on the south coast, to closer to 60 further north.

Saturday we'll be in between systems.  Although we should see more clouds than sun, no rain should fall, and high temperatures should be close to 60.

The next system will then approach as we get into later in the weekend and early next week.  This system will be a bit more complex, and likely consist of a series of slow-moving lows passing to our south.  Most likely, the systems will be close enough to bring rain to the state, but south of the area, keeping the state in the cold sector.  As far as the sensible weather goes, here's what I'll forecast:

Sunday- Rain arrives in the southwest late in the day, but waits until nighttime in the northeast.  Temperatures should range 55-60.

Monday: There could be a period of steadier, heavier rain in the morning, and then light rain lasts all day.  High temperatures in the mid 50s, and could be even lower than that.

Tuesday: For now, we'll assume skies clear, and it's a fairly nice, but chilly day, with highs in the low 60s.

All of this is subject to change.

Longer Range: Some ensemble guidance breaks down the cool, rainy pattern around the 8th-10th time frame for several days and may offer a preview at summer.  However, I generally use guidance that far out with a grain of salt, since it can change patterns too fast.

Now, here are some graphical looks into today's forecast:

Here is a look at the coastal low for later Thursday:

​

As we can see on this image, this guidance keeps the coastal low far enough offshore to keep rain out of Connecticut.  However, it is not far away from being rainy.  Changes like that happen frequently.  Now, here is a look at the potential rain storm for Monday.

As we can see, this low is a lot closer, and a much better developed low, so rain overspreads Connecticut, but perhaps not quite as heavy in the Northwest hills! Anyway, that's all for now! Enjoy the rest of your week!
-GP

Good evening and happy weekend from Southern Connecticut Weather!

Well, it had to come to an end at some point. The omega block that brought us days and days of spring time temperatures and sunny skies has moved on, and in its wake we will return to our more normal pattern. 

I, for one, mourn this great loss, but take heart spring fans! We are not going back to the pattern we had earlier this month, which featured endless days of rain and cold. 

Tonight through Sunday

Friday afternoon/evening satellite loop of the northeast United States. Note the spin from low pressure out in Ohio/Kentucky. 

The clouds, storms, and rain have dominated the landscape today, as you can see from the above image. Storms passed to our north for the most part, but Connecticut gets in on the rain overnight and into tomorrow morning, as an area of low pressure along an attendant cold front passes through the area. 

In heaver downpours, folks could pick up meaningful rain, but overall, this system clears quickly. After some lingering showers and clouds tomorrow morning, we will find a nice Saturday as things clear out.   ​

Sunday is beautiful with everything cleared out and high pressure building in. Temperatures will be around normal, and it should be a great day to get outside and enjoy beautiful Connecticut!

Monday/Tuesday
Sadly, the great weather doesn’t last long, as another cold front meanders its way through the region early in the week. Most of Monday looks fine, though we will deal with increasing clouds and shower chances by the time we get to the evening hours.

​Much of Tuesday looks wet as the front pushes through. Having some rain would be nice after a dry period, even if it does mean a messy day.

NRCC map showing the precipitation departure for the region during the month of April. Dry, but not exceptionally so. 

Wednesday through Friday
After the front clears Tuesday night, Wednesday looks like a great day. Sadly, that too doesn’t last long, as high pressure scoots offshore and another potential system make a run at the region. Friday in particular looks like it could be wet, but given how far out we are, this is far from a lock. 
​
All in all, we head back to a seesaw regime, but nothing terribly exciting or out of the ordinary for this time of year. Just the way we (well, most of us) like it!

GFS Ensemble depiction of precipitation anomalies across the US over the next week. We're wetter than normal, but not overwhelmingly so. 

The dailies:
Saturday: Rain showers early diminishing during the morning hours. Mostly cloudy early with gradual clearing by noon. Highs in the mid to upper 60s. Chance of rain early 60%.

Sunday: Sunny. Highs in the low to mid 60s. 

Monday: Increasing clouds during the day and showers by late afternoon/evening. Highs in the mid to upper 60s. Chance of rain 50% late. 

Tuesday: Rain showers throughout the day. Highs in the upper 50s to low 60s. Chance of rain 70%. 

Wednesday: Sunny with highs in the low to mid 60s.  

Thursday: Chance of showers, otherwise mostly cloudy. Highs in the low to mid 60s. Chance of rain 30%.

Friday: Rain possible, otherwise mostly cloudy. Highs in the upper 60s. Chance of rain 50%
Thank you for reading SCW!

-DB

Today was one of the more beautiful days in recent memory across the area.  There will still be beautiful days in the upcoming pattern, but the overall pattern will become more active and changeable across the area.

Tonight: With low relative humidites and dry soil, as well as clear skies and diminishing winds, radiational cooling should be able to take hold and temperatures should be able to fall rapidly after dark.  Lows should range from the mid 30s to around 40, possibly warmer in the urbanized locations along the south coast.

Tomorrow: Although there will be abundant sunshine, temperatures will be quite a bit cooler than those of today, especially across the southern zones, where it was significantly warmer than the northern zones today.  The air mass aloft tomorrow is significantly cooler than that of today.  As a result, high temperatures will generally be in the lower 60s, though the Bridgeport and New Haven areas could see readings a few degrees warmer.

Tomorrow Night into Thursday: With calm winds tomorrow night, there will be a much larger difference in temperatures between areas that are known to radiate well and urban areas.  Temperatures will range from near freezing in the typical colder spots to the mid 40s in the warmer locales.  Thursday should be a beautiful day.  Clouds may increase ahead of the next system later in the day, especially in the Southwest, but other than that, it should be a sunny and pleasant day, with high temperatures generally ranging from the upper 60s to around 70.  With the flow becoming southerly, coastal locations will be cooler than inland areas.  In fact, areas along the immediate southeast coast could be stuck in the low 60s, while the Connecticut River Valley could be into the mid 70s.

Longer Term: The overall longer term pattern will become more active and changeable.  The first system in the long term will occur at the very beginning of the long term period.  On Friday, a complex storm system will approach the region.  Basically, this system will be comprised of a frontal system with various waves of low pressure moving along it.  Although this forecast is fairly low-confidence, because we have frontal waves, and a lot can depend on the timing and exact location of the waves.  But for now, the best consensus idea is for the first scattered showers to arrive in the Southwest well before dawn and around dawn in the Northeast.  Rain should become more organized during the day, and may end during the later afternoon hours as a round of thunderstorms.  In general, the end timing for now looks to be from mid-afternoon in the Southwest to around the end of rush hour in the Northeast.  Temperatures on Friday should be fairly uniform with the clouds and precipitation- generally in the upper 60s.

On Saturday, skies clear and dew points lower again behind the system.  A pleasant day, with high temperatures generally in the 60-65 degree range.  

On Sunday, sunny but rather crisp for the time of year.  Clouds may increase late in the day in the Southwestern zones ahead of the next system.  High temperatures will generally stay in the upper 50s.  Morning lows could again dip below freezing in the northern half of the state. 

The next system, an overrunning rain storm, as the state stays in the cold sector, begins to affect the state on Monday.  Current models are actually showing some rain rotating into the eastern areas first.  Either way, the first showers should move into the state during the morning hours.  This system will likely not move much, so rain could continue on and off all of the day on Tuesday, and perhaps (going beyond the long term) even into part of Wednesday.  Since the state will likely remain in the cold sector, it will also likely be a chilly rain.  High temperatures Monday and Tuesday will probably not reach 60 degrees.

Looking into the long range, as advertised above, the pattern will likely be active and changeable.  This area often gets caught in the crosshairs between the warm air masses that move up across the Mid-Atlantic states and the cool, maritime air masses from Eastern New England and Eastern Canada.  This is exactly what could be happening in the long range, as various frontal boundaries look to move around very near the state.  This means that more often than not, rain may be falling, and there may be wide temperature swings from day to day.

Now, here is a look at the two upcoming weather systems in graphical format.  First, let's take a look at the system slated to effect the state on Friday.

​

Here we can see that although the low pressure system is over Maine, the trailing cold front is stretching from Northwestern Connecticut down into Eastern Pennsylvania.  A fairly significant area of rain over New York State, behind the cold front, (an anafrontal setup), is headed toward the state, especially the northern half of the state.

Now, let's look at the system that will be affecting the state Monday and Tuesday.

​

This map, valid midday Tuesday, shows low pressure near Philadelphia.  The heaviest rain by then is to our north over Massachusetts.  However, some rain remains across the state.  Obviously, positions of individual features on day 7 is far from certain.  A further north placement of the low would result in less steady precipitation, scattered thunderstorms, and warmer temperatures.  A further south placement of the low would result in colder temperatures and steadier and heavier precipitation.  Stay tuned!

That's all for now! Enjoy the rest of this beautiful day!

​-GP!