7Stormteam Weather Blog

First Tropical Depression Develops

The first tropical depression of the season develops just four days before the official start of the Atlantic hurricane season.

Tropical depression #1 is located at 37.3 N 71.0 W, about 250 miles east of the coast of North Carolina. Maximum winds are at 35 mph. This storm is moving away from land to the northeast at 17 mph and is not expected to affect any of the coastline. Conditions look fairly favorable for further development and it could become Tropical Storm Ana over the next two days. Even if that happens, the forecasted path shows the storm moving away from the coast.

 Early storms are not necessarily a sign that the season will be anymore active than when there are no early storms.

Stay tuned for the latest on TD #1.

Remember to pick up your KPLC 7 Stormteam hurricane tracking chart at any area Popeye's or right here at KPLC.

Memorial Day Weekend Guest; The Upper Level Low:

Well “weather” you like it or not, we’ll have a guest stopping by Louisiana for the weekend, and its left quite an impression on our friends in Florida.  Yes, it’s that pesky upper-level low we have been blabbering about all week long.  This system is providing the upper level support for rain and thunderstorms on its periphery, with best chances to the eastern side of the storm.  We also have need discussing that this upper level low is not “tropical” in nature, but since we only have a short amount of time to discuss that on the air, I figured it would be a good idea to try to explain in further detail what we mean by not “tropical” here on the weather blog.

There a few different ways for storm systems to form in our region.  First off, most storm systems start with two blobs of air known as air masses that begin to interact with one another.  Typically, a warmer & more humid air mass moves north while a colder & drier air mass moves south.  This temperature difference usually fires off a low pressure system with an associated cold front which is the leading edge of the advancing cold air and a warm front which is the leading edge of the advancing cold air.  This is commonly known as an extratropical cyclone.  Since this battle typically takes place across the middle to high latitude regions of the earth’s hemispheres, they give it the prefix “extra”, roughly meaning “outside” the tropics region.  These systems are usually guided and helped to strengthen by energy in the upper levels of the atmosphere.  Typically a trough or dip in the jet will help the low pressure at the surface.  From time to time, the jet stream pinches off a lobe of energy and spin.  This is known as an upper level low.  This upper level feature has a cold core and can sit and spin for days, meandering ever so slightly in any direction.  This destabilizes the air beneath it and allows for cooler, more cloudy and stormy days.  This upper level low is exactly what has formed over the Gulf of Mexico.  Notice below three things about the set-up of the upper level low:

1.  The heaviest rain and windiest conditions typically form away from the center of the low.
2. The surface low is tilted and offset from the upper level low.
3. The atmosphere in the upper level is cold and the winds are spinning in the same direction as at the surface: counterclockwise.

Since we’re dealing with a temperature driven system, we won’t be dealing with the development of a hurricane from it as we move through the weekend.  Hurricanes require a much different set-up in the upper levels of the atmosphere.  Although an upper level low would not aid in the maintenance of a tropical system, it can initiate a tropical storm system and quickly move away.  The conditions at the surface and the nature of this system are not favorable for our current set-up.

A tropical system forms in an area of relative minimal temperature changes; thus, it’s known as a tropical cyclone.  (Since it occurs in the tropical latitudes, we drop the “extra” prefix).  The ingredients needed are a pre-existing disturbance (such as a moving or dissipating upper low), very warm ocean water through a depth of roughly 100 feet, and very light winds aloft with some dryer air aloft.  The differences in the structure are as follows:

1. The heaviest rains and windiest conditions are right around the center of the storm.
2. The surface low is stacked directly under an upper level high pressure
3. The atmosphere in the upper level is warmer, relatively speaking.  Winds are spinning outward in a clockwise direction after exiting the hurricane at the top, with light winds otherwise aloft.

 

So the primary message here is the structure of this upper-level low will keep scattered rain and thunderstorms in the forecast for the weekend.  There is no threat for any tropical development, because on many levels, both literally and figuratively, we don’t have the structure in place at this time in our atmosphere.  Enjoy your holiday weekend indoors and outdoors, and stay tuned to KPLC for the latest weather information.

-Meteorologist Jeff Jumper

Tropical Weather???

For the latest on the upper level low pressure system currently near Florida go to the weather page of kplctv.com and click on the weather discussion in the video player. I have explained why I do not expect anything tropically to develop from thsi system as well as how it may impact your weekend plans. Her eis the direct link to the weather page: http://www.kplctv.com/Global/category.asp?C=4383&nav=menu66_3

Low over Florida

The low pressure system is over Florida and does not show any signs of tropical or subtropical characteristics this morning. The hurricane hunter mission scheduled for today has been canceled and the NHC gives the system less than 30% chance of becoming anything more than a rain event. The system still will be watched over the next couple of days and as it moves into the eastern gulf it will bring strong rain chances for the panhandle of Florida and gulf shores over the holiday weekend and over central and southern Florida over the next few days.

Stay tuned for updates.

Low Developing in the Gulf

Computer models are indicating that a mid to upper level low pressure system will form near the southeastern gulf over the next two days. In response to this upper level low, an area of surface low pressure is expected to form. Although models are differing in where the surface low forms, either in the southeastern gulf or over southern Florida, it look like the ending result is in close agreement. This area of low pressure will affect mostly Florida through the end of the week and then move inland near gulf shores bringing widespread rain. Now, here in SWLA we should feel minimal impacts but gulf shores will be a different story. Any plans that you have along the beaches this Memorial day weekend will likely be a wash-out.

Whether or not this system obtains subtropical characteristics will have to be nailed down in the next few days. It is unlikely that we will be dealing with a tropical storm, the environment is just not conducive for that yet.

It's not highly uncommon for subtropical storm to develop outside of hurricane season, especially this close to June 1. The last one was Subtropical Storm Andrea in May 2007.

Nevertheless, several inches of rain is expected in Florida and gulf shores over the weekend.

Stay tuned for the very latest this week.

Severe Weather Threat Over (posted 9:00pm 5-11-09)

The Severe Thunderstorm Watch which was issued earlier for all of our area was allowed to expire at 8:00 pm. The threat of further severe weather is over now and all the rain is over for the night too. Thankfully we really did not see much severe weather today; there were a few reports of small hail, all below severe criteria of ¾” diameter. An oil well was struck by lightning near DeQunicy as a strong thunderstorm moved through Beauregard Parish. For the latest on that story go to our homepage, www.kplctv.com.

Severe Thunderstorm Watch # 288 until 8:00 pm (posted 3:15pm 5-11-09)

The Storm Prediction Center in Norman, Oklahoma has issued a Severe Thunderstorm Watch which is in effect until 8:00 pm for the following parishes: Acadia, Allen, Beauregard, Calcasieu, Cameron, Jefferson Davis, Lafayette, Rapides, St. Landry, St. Martin, Vermilion, & Vernon. Thunderstorms have been rapidly developing in SE Texas and moving our way. Some of these will have the capability of producing strong damaging winds in excess of 60 mph and hail greater than ¾” in diameter. With any severe thunderstorm the possibility of tornadoes exists, but in this case that threat looks to be very low. Remember that a watch means conditions are favorable for the development of severe weather in or near the area that the watch covers. If a serious threat develops the National Weather Service will issue a warning; that will be your queue to take shelter. Stay tuned to KPLC for the latest information and further updates as they become necessary. Remember for the latest radar views you can logon to www.kplctv.com and click on the weather tab at the top. Once you are on the weather page you will see a link that says “parish by parish” radar views, this will give you the latest radar images by individual parish. You can also tune into the Southwest Louisiana Channel on digital TV 7.2 or Suddenlink cable channel 247.

5.3.09 Severe Weather Threat Dwindles

The severe weather threat has just about dwindled for this Sunday.  A few additional widely scattered thunderstorms continue to pop up across the area as the slow moving cold front creeps through the area.  Although the threat for severe storms is nearly over, the storms from earlier have dumped a great deal of rain and have caused some flooding problems which continue as of the five o’clock hour.  Just keep aware for any flooded areas and avoid them.  Keep with KPLC for the very latest updates.

-Meteorologist Jeff Jumper

Sunday 5.3.09 Severe Weather Update 11:15AM

The severe weather threat for southwest Louisiana and Acadiana continues this Sunday morning.  The SEVERE THUNDERSTORM WATCH set to expire at 11:00AM has been EXTENDED until 12:00PM CDT for Beauregard and Vernon parishes.  The SEVERE THUNDERSTORM WATCH for the remaining parishes is still in effect and scheduled to expire at 3:00PM.

The line of strong storms continues to push east, stretching along a line roughly from Huntsville, TX through DeRidder and Oakdale, east to the Mississippi-Louisiana border and farther east.  The early playmaker of this storm so to speak has been the damaging winds, which is a threat that still continues.  We’ve already seen numerous reports of downed trees through the morning hours in the northern part of our viewing area.  These storms are also dumping a large quantity of rain over Vernon, Beauregard, & Allen parishes, so Flash Flood Warnings have been issued for parts of the area.  Expect additional rain to continue to fall over these areas, so be very cautious of flooding along low lying areas and roadways.  The line of storms is now becoming more west to east, so rain will begin to pile up rapidly, with reinfocing storms running over the same area for the next few hours.  Expect flooding across Vernon, Beauregard, & Allen parishes in the next few hours.  If you do come across a flooded area, remember the motto: TURN AROUND, DOWN DROWN.

As a reminder, we want to hear from you after the storms pass.  If you have any damage reports or pictures, you could contact us in the following ways:
Multimedia & text: www.reportstorms.com****Preferred Method****
E-mail text: news@kplctv.com
Multimedia: viewernet@kplctv.com
Phone: 337-437-7568
Remember, YOUR SAFETY COMES FIRST!  Do not attempt to call or contact us during a storm; take the necessary safety precautions for you and your family.  Stay safe!

-Meteorologist Jeff Jumper

Severe Weather Details 5.3.09

The National Weather Service has issued a SEVERE THUNDERSTORM WATCH for parts of SWLA and Acadiana.  The WATCH is in effect this Sunday
UNTIL 11 AM: Beauregard & Vernon
UNTIL 3 PM:  Acadia, Allen, Calcasieu, Evangeline, Jefferson Davis, Lafayette, Rapides, and St. Landry.

A line of strong storms is pushing rapidly through our area from west to east.  These storms already have a history of producing damaging gusting winds in excess of 70mph.  A severe thunderstorm warning has already been issued for the line of storms as they move through Vernon parish.  Keep alert for changing weather conditions.

Here is a look at the watches:

Here is a look at radar at 8:40AM:

Severe thunderstorms are capable of producing large damaging hail of at least ¾” in diameter (penny size), strong damaging winds exceeding 58mph, or tornadoes.  All thunderstorms contain lightning, which could prove deadly.  Storms will produce heavy downpours which cause reduced visibility and could flood low lying areas and roadways.  If you approach a flooded roadway, TURN AROUND-DON’T DROWN.

AFTER the storms pass and you are well out of danger, we’d like to hear from you.  If you have any damage reports or pictures, you could contact us in the following ways:
Multimedia & text: www.reportstorms.com****Preferred Method****
E-mail text: news@kplctv.com
Multimedia: viewernet@kplctv.com
Phone: 337-437-7568
Remember, YOUR SAFETY COMES FIRST!  Do not attempt to call or contact us during a storm; take the necessary safety precautions for you and your family.  Stay safe!

-Meteorologist Jeff Jumper