Upper Level Low Vs. Hurricane

UPPER LEVEL LOW VS HURRICANE...

Over the past few days we have been tracking an upper level low that developed over the southwest US and has slowly been moving thru the southern Plains.  I have a had a few say to me this looks like a hurricane because it is so circular and symmetrical.  I thought I would briefly explain the structure of upper level lows and hurricanes.  So you can see the difference in the way they look.

First here is a look at the Satellite and Radar view from 9pm on Thursday.  Notice how the center is over NE Oklahoma with the clear circular nature around the low.  I had one twitter follower say to me it looks like a ciniman roll.  Ummm doesn't that sound good!

UPPER LEVEL LOW

This system is an upper level low that developed in the mid-lattitudes.  This is where the battle zone is between the warm air in the tropics and the colder air in the Arctic.  The US resides in the mid-lattitudes and the reason why we get active weather is because the Earth is always trying to balance out the temperature.  The Earth wants to bring warmer air northward and colder air southward.  The Earth wants to even out the temperature, but that is impossible because of unequal heating from the sun.  Upper level lows form as a result of the Earth trying to balance the temperature.

An upper level low is a cold core system.  That means that the column of air above the ground features cold air.  The structure of the system has an area of Low pressure at the surface and an area of low pressure in the upper levels of the atmosphere.  As air warms at the surface it rises freely into the cooler air and will form showers and thunderstorms.  This is what we have seen the past couple of days.

Here is what a cold core low looks like.

HURRICANES

A hurricane is a warm-core system.  A hurricane forms in the tropics and is fueled by air quickly evacuating the upper levels of the atmosphere.  What this means is that air in the upper part of the atmosphere is moving away from a location, air at the surface then rises to fill the void of the air that moved away.  This gets the ball rolling for a tropical system to develop.

Here is the structure of a hurricane or tropical storm.  There is low pressure at the surface and high pressure in the upper levels of the atmosphere.  The High pressure ventilates the air and the low pressure forms as air rises to fill that ventilated air.  A hurricane is also warm core.  The air is warm throughout the column.  This is also one of the reasons why you don't see a lot of lightning in hurricanes.  The air temperature throughout the atmosphere is not conducive for ice formation.  You need ice (hail) in the clouds to generate electricity which generates lightning.

Here is the structure of a hurricane...