Weather Talk: Closed Low impacts and major cold front
POSTED: Sunday, March 9, 2014 - 8:22pm
UPDATED: Sunday, March 9, 2014 - 8:31pm
(KETK) - Tyler, Tx — This weekend, you may have heard me mention a “closed” area of Low pressure in the Baja Mexico region. I would like to explain what a closed low is, how it will impact portions of East Texas. I will also talk about a strong cold front that will put an end to the warm weather we will see Monday & Tuesday.
A closed low is defined by the National Weather Service as “A low pressure area with a distinct center of cyclonic circulation which can be completely encircled by one or more isobars or height contour lines. The term usually is used to distinguish a low pressure area aloft from a low-pressure trough. Closed lows aloft typically are partially or completely detached from the main westerly current, and thus move relatively slowly.” In other words, it is an upper level area of low pressure that is not moving with the same speed as the circulation of the overall winds. These lows are a part of the main flow, but move at their own pace or until stronger winds downstream force it to move eastward.
Here is what the closed low looks like. This is the jet stream pattern currently. The closed low is incorporated within a trough—an area of lesser height values, and representing an area of low pressure at the surface.
This low will impact us as it returns to the main flow of the jet stream by providing a chance of showers and a thunderstorm for our Deep East Texas counties.
We have talked about positive vorticity—meaning upward vertical motion and lift in the atmosphere. This will aid in the rain chances Monday night into Tuesday morning for our southern areas.
That system quickly moves out, and temperatures on Tuesday rise into the middle and some upper 70s. Enjoy Tuesday, because Wednesday promises to be cooler, blustery, and very windy.
STRONG COLD FRONT
By Tuesday evening, the cold front will be entering the Central Texas area. It looks to arrive in Tyler between 10PM and 3AM. Here is the GFS & NAM for 7PM Tuesday Night, 1AM & 7AM Wednesday morning.
Much cooler air settles in for Wednesday. We will see plenty of sunshine, but highs will be in the upper 50s and low 60s with very north winds anywhere between 15-25 miles per hour and gusting to near 30-35 miles per hour at times.
The KETK Weather Team will be tracking the cold front carefully over the next few days, and we will keep you informed with the latest forecast.