Noah Bergren Aspiring broadcast meteorologist

Icy Mix to Impact Tuesday Morning Commute

Our first winter storm of the season arrives tonight into the day Tuesday. Warm air in the mid-levels of the atmosphere will prevent this storm from being a snow event, and most areas across Connecticut will not see much if any in the way of snowfall.

Precipitation starts around midnight as snow statewide. There can be a quick coating of snow across the state, up to an inch in the hill towns - before a quick changeover to a mix.

The wintry mix of sleet and freezing rain falls from 2am until around 9am. A light accretion of ice is likely across inland Connecticut. This will make driving hazardous, especially on untreated areas.

The frozen mixture changes to plain rain along the shoreline first, then gradually from south to north as temperatures moderate above freezing. By 10AM most areas will be rising above freezing and changing to plain rain. However, some of the hill towns and deep valleys in northern Connecticut may see ice until the noon hour. The evening commute is good across the entire state with rain tapering off.

The image below is a forecasted atmospheric sounding for Hartford, CT at 8am Tuesday morning. The warm layer around 800mb indicates rain falling into a sub-freezing environment at the surface.


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Forecast discussion: Heading into Father's Day Weekend

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NAM model - simulated radar reflectivity valid 5PM local time Tuesday evening.

Temperatures were held in the 60’s across Connecticut on Monday, and with the rain falling, it certainly didn’t feel like mid June outside. Monday’s rain has since moved out, and Tuesday will be a notch better than Monday was.

As a cold front approaches from the west, this will trigger some scattered showers and thunderstorms to form across NY State and Eastern Pennsylvania. These storms will move through Connecticut during the afternoon hours, gradually weakening as they move east. Don’t be surprised to hear some rumbles of thunder and lightning, and possibly some gusty winds as any storms move through.

Wednesday features sensational weather, with no humidity and mainly sunny skies. Temperatures will be a few degrees on either side of the 80 degree mark.

An area of disturbed weather swings through on Thursday. Mixed sunshine and cumulus clouds appears likely, with the chance of some scattered showers and thunderstorms during the afternoon hours. By no means is Thursday a washout.

Improving weather settles in for Friday into the first half of the weekend, with lots of sunshine and pleasant temperatures in the lower 80’s. The humidity won’t be too bad, either.

However, clouds seem to increase on Father’s day, as well as the humidity. Oppressive levels of humidity, with dew points near 70 are possible by Sunday evening.

The remnants of some Gulf of Mexico moisture, in association with what may be Tropical Storm Bill, will approach the area. The exact timing of this rain will be fine tuned over the coming days. Meanwhile, Saturday definitely looks like the best golf day, beach day, BBQ day, and outdoor day of the weekend.

Enjoy the rest of your week!

Noah

Forecast discussion: Heading into May

Fast approaching the final days of April, May is right around the corner. Snowflakes, skiing, and bitter cold will soon be a thing of the past, and those winter jackets will be replaced for bathing suits soon enough. Looking at the weather currently across the eastern half of the United States, we can observe that areas east of the Mississippi River, and along the east coast are dry currently. Looking on the doppler radar image from late Sunday afternoon, we can see that there is some unsettled weather across Texas, and on up along portions of the plains states and into Colorado.

Screen Shot 2015-04-26 at 4.42.11 PM

Note that there are currently no major storm systems in the contiguous United States. This will change as we head throughout this week, especially by Friday. In the short term, an offshore storm system will help form some widely scattered rain showers across New England Monday and Tuesday. By no means will these days be a washout or totally cloudy, but some sprinkles are likely from time to time. By midweek, skies will clear from Pennsylvania to Connecticut, leaving the area with pleasant springtime weather. Temperatures in the 60’s, and fair skies can be expected Wednesday into most of Thursday. Now as we head into Friday, there are growing signals for a pattern-changing coastal storm to impact the Northeast. Seen below is the 126hour frame of the Sunday afternoon run of the GFS model, valid for midday Friday.

gfs_namer_126_1000_500_thick

I’m not sold on the idea as of yet, but it’s becoming increasingly likely to come to fruition. If you happened to read my local forecasts for Connecticut and Pennsylvania for the week, you will notice that I have not yet included this chance of rain by Friday this week. For now I’ll keep just clouds in the picture for then. This storm has the potential to bring a chilly rain to most of the New England area during the day Friday, as portrayed by the GFS shown above.

Looking ahead beyond this weekend, there are strong signals pointing towards a significant pattern change. Currently this week across the United States, a large trough is entrenched over the east coast, all the while a potent ridge is strung out over the west coast. As we head into the first week of May, this pattern is forecasted to do a 180, placing a ridge in the eastern states. This would allow warmer air to surge north across the eastern third of the United States. Reading over some other numerical model data, we may finally return to temperatures in the 70’s come May 4th or 5th. Good news for just about everyone that has had enough of the cool, cloudy weather. At this point, that is probably most of the people living in the Northeast, especially after the winter we had.

What you need to know:
Summing it all up, the weather outlook for this week is for times of clouds, and sunshine, with a few rain showers possible during Monday in Pennsylvania, and Tuesday in New England. Clearing skies, with seasonable temperatures near 60 midweek, before we have to watch the possibility of a coastal storm to impact the region late week- which likely will set the stage for a significant pattern change to much warmer weather as we head into May.

Thanks for reading.
I hope you have a great day.

Send me your weather questions via email, or on Twitter!

The Blizzard of 2015

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After quite the quiet winter season thus far, ole’ man winter is set to make an illustrious return to New England. A Clipper System made the trek from Southern Canada all the way to the Carolina coast this afternoon. What’s happening now is this clipper system is exploding into an intensifying area of low pressure off of Cape Hatteras, NC. You can see this below in the Water Vapor Imagery Loop. The moisture for this storm is coming all the way from the Caribbean and Atlantic Ocean.

wv-animated

Mixing will not be an issue throughout this storm, as we have cold air firmly entrenched throughout the atmosphere- thanks in part to a high pressure area over Eastern Canada, which is supplying a healthy supply of cold air into this storm. The storm will continue to rapidly strengthen, or “bomb-out” so to say in meteorology, meaning the storm will rapidly enlarge in diameter and intensity. The storm will track NE to just south of New England Tuesday Morning. Here are the storm specifics with everything you could possibly want to know about the storm.

-The storm will peak from 12am to 12PM Tuesday. Travel will be nearly impossible.
-Whiteout conditions Tuesday Morning from the New Jersey coast, all the way to Maine.
-A Blizzard Warning is in effect for all of CT, and Winter Storm Warnings are in effect for portions of inland Massachusetts, Vermont, New Hampshire, and New York.
-The snow will taper off and end Tuesday afternoon.
-Wind gusts during the height of the storm will be in excess of 40 to 50mph inland, and in excess of 60mph along ocean facing coastlines.
-Scattered power outages are likely, especially along the coast.
-Significant blowing and drifting of snow; some drifts over 5 feet tall are possible.
-Most of CT will end up with near 15” to 18” of snow.
-Depending upon where a heavier band of snow sets up, anyone under this narrow (<30miles wide) band could see upwards of 30”+ of snow.
-Do not go out traveling during the storm.

Here are my snowfall thoughts in a graphical representation:

GOOD

Stay safe throughout the storm. Enjoy the snow from inside!
Please send me any storm photos to photos@nbergweather.com, and I may feature them on my website.

My 2014-2015 Winter Forecast

OVERVIEW14-15

Welcome

Welcome to my website, and thanks for visiting. The calendar has now flipped to November, meaning we are that much closer to another winter season in Connecticut, and across the region. It’s that time of year where I publish my thoughts regarding the upcoming winter. In this detailed discussion, I will go over how, and why I believe this winter will be either cold and snowy or warm and rainy. Or maybe somewhere in between? I will go over some of the most important scientific concepts behind my thinking, as well as some historical facts, and of course my actual winter forecast. Keep reading to find out. Without further ado, let’s get into it.

Weather Forecasting in General

Allow me to talk about a few quick things regarding weather forecasting, specifically long-range forecasts. In the short range, forecasting within a couple of days, Meteorologists use a wide variety of tools, knowledge, and equipment to forecast the weather. One of the best tools used are the suite of computer models available to scientists. Computer models get ingested with all sorts of weather information, from weather balloons, to real time reports, satellite data, and other various weather readings. These models then compute complex sets of mathematical equations, such as partial differential equations, for example. This process takes a few hours to complete, and then the result is a computer generated forecast of the state of the atmosphere at a given point in time, based off of the initial conditions. As the time frame gets further and further away from the initial data set, the amount of error increases, leading to variability across different computer models. This is why computer models are only pretty accurate out to a couple of days, and then beyond that, not so much. Even with slight initial errors in the data, these small errors become exponential over time. The rough sketch graph below expresses this.

Screen Shot 2014-10-31 at 11.11.17 PM

This is why long range weather forecasts are challenging, difficult, and volatile. However, there is a slew of other trends, amongst other indicators in the atmosphere, to try to predict general trends over long periods of time. Before I get into the science behind my forecast, remember to take long range forecasts with a grain of salt. While I’m not a huge fan of long range weather forecasting, it’s always nice to look ahead. When market analysts, stock brokers, and financial advisors try to predict the future of the stock market, they issue long term forecasts. This is the same thing. Remember, that Meteorology is far from a perfect science. Scientists and researches across the globe are continually studying the weather, formulating the future of better weather forecasting. Now lets delve into some of the meteorological topics behind this upcoming winter.

The Science behind Long-Range Forecasting

When Meteorologists try to forecast the weather several weeks and months in advance, they look at things with a more global perspective. In order to predict the weather locally, we have to look at how the rest of the worlds’ weather is. There are several teleconnections Meteorologists use to forecast the weather far out in the future. Here are a couple of both the most important, and useful weather teleconnections, and how I think they may pan out over the 2014-2015 Winter Season. I will first describe what these teleconnections are, and then go into how they may impact this winter later on.

ENSO

ENSO, short for El Niño Southern Oscillation, has to deal with the temperature of the ocean waters in the equatorial (South-Central) Pacific Ocean. ENSO has a very large role in our weather, especially over extended periods of time. There are three phases, or states within ENSO - La Niña, ENSO Neutral, and El Niño. When the ocean waters of this region in the South-Central Pacific Ocean are warmer than average, this is called El Niño. Likewise, when these sea surface temperatures are cooler than average, this is called La Niña. Finally, when these temperatures are near normal, that is ENSO Neutral. El Niño is formed from lessening Trade Winds over the Central Pacific Ocean. This allows warmer ocean water to flow east into the Eastern Pacific Ocean.

As you can see in the graphic above, the Equatorial Pacific is currently slightly warmer than average. This is denoted by the light orange shading, representing about a 1 degree temperature departure from normal. This indicates a Weak El Niño is present. Over the next couple of months, as you can see in the image below, a weak El Niño is forecast through this winter. Look closely at the first couple of months, and observe how the mean forecast of the line is around 0.5 - 1. These values are what indicates the weak El Niño.



This all may sound arbitrary, but believe me that ENSO has a direct relationship with our weather in the United States. El Niño has a positive correlation with winter weather here in New England. Generally, a weak El Niño in the Equatorial Pacific equates to a relatively cold and snowy winter here in the East. A strong El Niño typically equates to mild and dry conditions in the Northeast. La Niña, on the other hand, features a warm and dry theme from the Plains states into the Southeast, and a wet and cool feel in the Northwest region. Below are some examples of the most common effects of an El Niño, La Niña, and weak El Niño winters on the United States.

Typical-El-Nino-Winter77777
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Three images above are from AccuWeather, Inc.

So to sum things up, the signs point towards a weak to moderate El Niño to persist through the winer months of this season - potentially leading to a relatively colder and snowier winter.

North Atlantic Oscillation (NAO)

As I stated earlier, there are many different oscillations and indices in the science of meteorology. Two of the most important are the North Atlantic Oscillation (NAO), and the Arctic Oscillation (AO). I will talk about the AO in the next section. So what is the NAO, and how does it impact our weather locally in the Northeast. A lot of the NAO has to deal with a term called “blocking” - there is a lot more to this, but a good portion of it relates to this. I want you to think of the Jet Stream and the atmosphere as a flow of water through a hose. Remember, wind currents thousands of feet above our head are what control the movement and patterns in weather. Often times, a Negative -NAO induces a blocking pattern. For instance, try to imagine weaving a hose from one end of your hose to the other. You would have to weave around corners, obstacles, etc. Going around the corner of a hall, for instance, causes a kink in the hose, and slows down the flow of water through the hose. This is basically what a -NAO does in our atmosphere, and why we get many of our big snowstorms during a -NAO phase. How it works is that a high pressure area aloft forms over Greenland. This causes the Jet Stream to dig south across the Eastern half of the United States, allowing for colder air to filter down from Canada. This -NAO also promotes slower storm progression, especially off the East Coast. A +NAO is the exact opposite, with a low pressure area over Greenland, and a more progressive, warmer airmass over the Northeast.



Arctic Oscillation

Another meteorological indicator atmospheric scientists use to forecast the weather is called the AO, or Arctic Oscillation. The Arctic Oscillation is a climate pattern described by winds circulating counterclockwise around the Arctic circle, at roughly 55°N latitude. The AO represents the state of atmospheric circulation over the Arctic. When the AO is in a positive phase, the ring of very strong winds around the Arctic tends to confine cold, arctic air masses to the polar regions. When the AO is negative, the ring of winds around the Arctic becomes weaker, along winds to be more distorted and scattered. Think of it this way, the AO acts as a dam, and when it's in a negative phase, it leaks and lets very cold air spill out and funnel its way south, into the mid-latitudes of the Northern Hemisphere. This can result in cold, stormy weather in New England. If you look below, you can see that the AO is forecast to turn sharply negative over the month of November. Just as a side note, it is interesting to find that we have seen many of our major storms in Connecticut over the past few years, during a negative AO phase.



There is currently no way to forecast which phase the Arctic Oscillation will be in three months from now, so we just have to keep an eye on it over the coming weeks. However, based upon history, we know that certain AO phases occur during certain ENSO states, etc. Hence, I wouldn’t be surprised to see the AO remain mostly negative for at least part of this winter season.

Pacific North American Index (PNA)

One of the less common, but still very important meteorological tools, the Pacific North American Index is a very complex index meteorologists refer to when making long range forecasts. Without getting too technical, there are two phases of the PNA. A positive, and negative phase. The main causes for these, and there effects on the United States don’t come from around here. The PNA is greatly impacted by atmospheric patterns in the Pacific Ocean. A +PNA, which usually comes with cold and snowy weather in the Eastern States, is caused by a large ridge forming over the West Coast. This causes, in coordination with other teleconnections, a trough to form in the Jet Stream east of the Mississippi River. This promotes colder air to make its way into the East. A positive phase of the PNA is the exact opposite, commonly found with warmer spells and less snow here in the Northeast. Again, while there is no way to forecast any of these three teleconnections months in advance, we can get a handle of their trends over the next month or so. Over the coming weeks, it looks like the PNA will remain in a slightly positive phase, supporting the idea of colder weather here in the East. Below is a chart showing the computer model forecasts of the PNA over the coming weeks. As you can see in the first box, the red lines indicate the future state of the PNA.



Below is a graphic summing up three of the major teleconnections within Meteorology. The North Atlantic Oscillation, Arctic Oscillation, and the Pacific North American pattern. While there are many things that must come together for us to see cold and snowy weather, generally, we experience our coldest and snowiest periods during a -NAO, -AO, and +PNA phase.

naooapna

Pacific Decadal Oscillation (PDO)

As you can see in the graphic below, the temperature and state of our weather has large fluctuations. However, if you look closer, you will see that over the past few decades, the Pacific Decadal Oscillation generally rides about a 25 year pattern of progressively colder winters, followed by a 20-25 year period of warmer and wetter seasons. This is why during the time of the 1960’s and 1970’s, snowstorms were very common across our region, as some of you may remember. Then during the 1980’s, 1990’s, and early 2000’s, a positive phase of the PDO was accompanied by generally warmer and wetter [winter] seasons. Now in present day, it appears as if we are entering another naturally occurring cycle of progressively colder and snowier winters. This supports my idea of this winter being cold and snowy in New England.

PDO.svg
Image from http://commons.wikimedia.org/wiki/User:Giorgiogp2

Here is an example of the +PNA phase, showing the warmer SST in the Eastern Pacific Ocean, contrasted with the Cooler waters of the Western Pacific. The graph above represents values of the PDO, which as I explained, usually has been known to flip over the course of 20 or so years.

PNA-16
Image from http://commons.wikimedia.org/wiki/User:Giorgiogp2

My Winter Forecast

I realize that either I have bored you to death, or you were hopefully interested in some of the things I already talked about. Now its time for my actual winter forecast. Let me get right to the point that you all are probably waiting for- I think it is going to be a very cold, and somewhat snowy winter in Connecticut / Southern New England.

Here are my forecasted numbers for the 2014-2015 winter season.

~ In Connecticut and Southern New England, temperatures may end up -1 to -3 degrees below normal on the season.
~ Southern New England may also see a surplus of anywhere between 25% and 40% of the normal amount of snowfall.
~ In Hartford, CT, the average amount of snowfall each winter season (based on several decades of weather records), is around 40”. I expected the Hartford area to be between 50” and 60” of snow this season. For the sake of giving a more definite number, I’ll guess 55” as that number.

The biggest thing I think this winter will be known for is its early start. I strongly feel that winter will get off to an early start, as soon as the end of November. Based on the current Meteorological teleconnections, the AO will be turning sharply negative during the middle and end of November. The NAO will also be slightly negative. The combination of both the NAO and AO will provide a lot of blocking in the atmosphere, likely promoting the formation of coastal storms off the East Coast. I think that late November, and especially December will feature times of cold and snow. January may feature some swings in temperature, maybe even some thaws, before later in February into early March we may see another shot of cold and snowy weather, before warming back up again during the end of March.

I realize the long length of this blog, but I wanted to create a very detailed post about what’s going on. There are many other Meteorological factors that I did not mention, such as the Eurasian Snow, Solar Activity, Volcanic relationships, and weather records and analogs. Many of these support my thinking of a cold and snowy winter here in Southern New England.

Here is a graphical summary of what I expect across the United States this winter:

Temperature Forecast

TEMP14-15

I expect the areas shaded in light blue, to finish the winter season around -1 to -3 degrees below normal. Areas of the Mid-Atlantic region, and the Southeast may end up -2 t0 -4 degrees below normal. I think the Southeast will be in for a cold winter. Meanwhile the West Coast, and especially the Pacific Northwest should continue to stay generally mild, ending up about +1 to +3 degrees above normal for this upcoming winter.

Precipitation Forecast

PRECIP14-15

In terms of precipitation, most of the big I-95 corridor will end the season with above average snowfall. This includes Connecticut and most of Southern New England, and down along the East Coast (shaded in light blue). The Mid-Atlantic will have well above average snowfall, (dark blue shading) by the end of the winter. In terms of the ongoing drought in the Southwest, some rain may help the drought, especially in the second half of the winter months. Conversely, the Pacific Northwest should expect dry conditions with below average rainfall on the season.

Highlights

OVERVIEW14-15

Summing things up, I think that the Northwest region will generally be warm and dry throughout the winter. This winter may be known for being very chilly, especially in the Southeast region. There certainly are some chances for an Ice Storm or two in this area. The main thing that I think this winter will be remembered for in the Northeast is how early the snow and cold come. As I said earlier, I strongly feel that the end of November, and especially December will feature periods of cold and snowy conditions. However, the pattern may break down temporarily around January, leading to possibly wide temperature swings and a good thaw or two. This is before the cold should re-establish itself in the East as we head into February and early March, leading to a few more snow threats.

Unlike last winter, this winter may not feature frequent snow storms here in Southern New England. I think there will be less frequent snowstorms this year compared to last season, with the chance of a few big coastal storms as well.

Conclusions

Time for some meteorological “legal-copy” - just kidding. There is really no way to definitely forecast the weather months and months in advance. We can really only see trends that look like they may develop in the long range. Remember that Meteorology is an imperfect science. That is why when Meteorologists issue predictions, the word forecast is present within the actual forecast. Each and every day, scientists around the world are studying the atmosphere to better comprehend how the weather works. Just a mere 30 years ago, weather forecasting was nothing like it is today. With continued research and devotion, Meteorologists will someday be able to forecast the weather well in advance. The next time you watch a Meteorologist give a forecast on the TV, really listen to what’s being said, as opposed to searching for what you want to hear. Just like any other type of forecaster, whether it be in the stock market, or private industry, forecasts are not meant to be 100% accurate. There is a lot more that goes into developing that vintage “7-Day Forecast” graphic that we all see than just looking at the sky.

Thanks for reading!

I will continue to have my updates and forecasts throughout this winter season, on my website, as well as on social media, on Twitter @NbergWX, and Facebook at facebook.com/nbergweather. If you ever have a question, or comment about the weather, send me an email at nbergweather@psu.edu, and I will do my absolute best to try to help.

Have a wonderful rest of your day.