Wow What a Cold!

Winter is going to hit us hard this week. The image below will explain why:

The Red line that is extending its way into the Alabama and Mississippi is the 540 pressure line of the upper atmosphere. This line is equivalent to roughly 32 degrees at the surface. It is generally pretty impressive to have that line extend that far south, but what is more amazing is the 510 pressure line. This line is usually associated with extremely cold temperatures that can easily dip below freezing with wind chills in the negative double digits. That 510 line of air usually hangs around in northern Canada. If it ever rears its ugly head it would usually affect only the states of North Dakota, South Dakota, Minnesota, and Wisconsin. This extremely cold air looks like it will be sticking around for the next couple of days. The brunt of that air should exit the region by January 25th, which is when we may see our first shot of precipitation for much of the Midwest pending any lake effect snow that may happen.

I know it is the middle of winter and everyone is most certainly prepared but here are some essential items if you need to trek around campus or walk for your car to the office.

I hope everyone has a nice week. Stay warm out there the extreme cold will only last a matter of days!

Winter is on its way

One of the greatest times of the season is Thanksgiving. Between the Turkey, Football, and the fight for Black Friday deals a wave of Winter has decided to make its way into the Midwest and Northeast this holiday weekend. The upper Great Plains and Montana have already been battling winter's wrath with Blizzard and Winter Storm warnings punishing the region. Now I can honestly say that the winter season is here to stay for Midwestern and Northeastern families.

Our Thanksgiving Day in Indiana was beautiful. We experienced temperatures reaching upwards of 60 degrees with excess amounts of sun. It was perfect weather to go out and throw the football, eat food, drink beverages, and have a great time. During the late evening hours a low front bullied its way through the Midwest with rain and clouds, which led to a drastic temperature change for Friday. 

Friday was a brutal welcoming of Winter with snow flurries invading the region. Also, the first bouts of lake effect snow hit home in Ohio, Pennsylvania, and upstate New York. Is this just a precursor to the winter we will receive? Only time will tell.

We will be posting on weather related discussing later this week.

Thanks,

The Stratustatus Team

Cool Temps for the East: Teleconnection Influences

     Despite the official meteorological start of Autumn still being a few days away, the majority of the East Coast has already been feeling the cool temperatures this week. The passage of two strong cold fronts left overnight temperatures in the mid to upper 30s on Tuesday evening for much of the Great Lakes region. In Northern Minnesota, overnight temperatures dropped below 30 degrees, prompting freeze warnings for much of the area. It's quite an amazing flip from the unbearable heat we all experience this summer. Now you might be wondering what is causing this swift change in weather; the answer is lies within shifts in teleconnection patterns

     A teleconnection is a statistical linkage between climate anomalies over a large distance. These linkages interact with each other in various ways, shifting between positive and negative phases, and ultimately affecting weather and climate patterns for certain parts of the world. Phase shifts for most of these teleconnection patterns can be observed in changing sea surface temperatures for lengths of time. The two teleconnection patterns we will be focusing on with regards to the Eastern U.S. cool down will be the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO).


The North Atlantic Oscillation


     The NAO is a fluctuation in differences between the semi-permanent pressure features in the Atlantic known as Azores High and the Icelandic Low. In the positive phase of the NAO, the two pressures strengthen, increasing the strength of the jet stream. The strong jet stream prevents cold air from the Arctic intruding southward into lower latitudes, keeping the Eastern U.S. warm and wet. In the negative phase, the Azores High and Icelandic Low weaken, in turn weakening the jet stream and increasing the amplitude of troughs and ridges. The increased meridional flow can promote a blocking pattern, keeping a trough located over the eastern half of the country.

     We are currently in a negative phase of the NAO, resulting in the intrusion of Arctic air into the Great Lakes and Northeast regions of the United States. This negative phase has also resulted in a well-established a blocking pattern in the jet stream, keeping this cold air in the region. Below is a look at the current 500 millibar heights showing this pattern:

The Arctic Oscillation



     The AO is related to the pressure differences in the Arctic and midlatitudes. During the positive phase (pictured on the left in the above graphic), strong low pressure in the polar region strengthens the east-west flow of the jet stream, locking cold air in the Arctic regions. When the AO shifts into a negative phase, zonal flow of the jet stream weakens and allows for cold air to move into the midlatitude regions.

    Above is the current AO index. Currently, the AO is also in a negative phase, indicating strong polar air infiltration into the U.S. This, in combination with the negative NAO phase has resulted in the prolonged below normal temperatures for the Great Lakes, Upper Midwest, and Northeast. The blocking pattern appears to persist for the next week, bringing waves of Arctic air into these regions. Below is the five day temperature anomaly including this coming weekend.





However, forecast models are indicating a shift in these indices, leading to the return of slightly warmer air in the later half of the 0-16 forecast period. Below is showing the five day temperature anomaly two weeks out.



Graphics courtesy of WeatherBELL Models, the Climate Prediction Center, and NSIDC.

Living in the Midwest

During our daily look at the models we noticed a rather large event on the way.  A higher pressure system is sitting out over the western plains pushing a front eastward into the Midwest.

                                                 http://www.wunderground.com/maps/

Right now the storms are already stretched out long enough to cover a couple states.  As the storms push eastward into the evening models suggest they will strengthen.  At around 23z(7pm eastern) the storms are stretching from Oklahoma through Indiana.

                                              (high resolution rapid refresh from NOAA)

In the next 4 hours the storms strengthen quickly and pretty much cover the state of Indiana and also cover large portions of Illinois and Kentucky.

                                                                3z(11 pm eastern)

Through out The night it will weaken as it moves in a more north eastern direction.

The main issues associated with this storm are going to be wind and rain.  It will be happening overnight on a well known day of celebration(happy weekend to all)  as well which will complicate the situation.  Just remember to drive safe and smart.

Looking into tomorrow these storms look like they are going to push into the east coast bringing rain stretching from Maine all the way down to Georgia.

Ingredients for Hurricane Development

People can compare hurricane development to daily cooking instructions. A hurricane requires several ingredients to make the storm strong. If you take away or reduce some of the ingredients the hurricane will begin to weaken or lack the flavor of its true recipe.

The first and most possibly most important ingredient in hurricane development is water temperature. Hurricanes are considered warm-core systems, which means they require warm moisture to function and operate. The temperature threshold for tropical development is 80 F at the waters surface. The warm water increases the evaporation rate of the surface water. This in turn generates water vapor and cloud development.  Along with very warm surface temps there needs to be a deep layer of warm water to continuously feed the storm. In late summer, Water temperatures within the Gulf of Mexico and Caribbean reach these temps rather quickly due to the shallow ocean depth.

The next ingredient in hurricane development is the storm’s accessibility to moisture at all levels of the atmosphere. If the storm were to come into contact with a pocket of dry air the system will significantly begin to weaken in intensity.

A hurricane develops vertically as well as horizontally across a region of the Ocean. This can produce a system that covers large area. The high cloud development can be hindered if there is too much vertical shear at the hurricanes location. Shear is the change in direction of wind at different heights within the atmosphere. If there is too much shear the clouds at the top of the storm can blow away, which ultimately destroys the system.

The next thing to set a hurricane in motion is the creation of spin or rotation of the cloud and thunderstorms. The phenomena called Coriolis Effect is created by the spinning motion of the earth. The closer the storm is to the equator the weaker the rotation in the atmosphere, which can destroy the storm.

The last ingredient to the hurricane recipe is the collection of thunderstorms that flow off the coast of Africa into the Atlantic Ocean. These westward moving storms ,if strong enough, can be considered a tropical wave. As the thunderstorms and showers move across the ocean they can strengthen into stronger tropical disturbances but often times weaken and dissipate out at sea.

These required ingredients are needed to make or break a powerful Hurricane. Warm water, moisture, little shear, rotation, and tropical waves each play a important part in the storms cycle.