Weather Talk: Cooler and drier Friday
POSTED: Thursday, April 3, 2014 - 9:06pm
UPDATED: Friday, April 4, 2014 - 9:09am
(KETK) - Tyler, Tx — 1:45AM Update:
We are now tracking the cold front moving through East Texas. As of 1:45AM, it was moving through Wood county. Behind this front, much cooler and drier air will be filtering in.
Showers and storms remain likely through the next couple of hours as the cold front picks up steam and moves through East Texas quickly. Most areas are under a Tornado Watch until 4AM, but the tornado threat looks to be very slim to none. The severe potential has weakened considerably due to the upper forcing has moved to the Northeast where the strongest part of this entire storm system is.
When we wake up on Friday morning, expect much cooler temperatures--some 10-20 degrees different than in previous days. Highs tomorrow will be in the upper 60s and lower 70s. Sunny skies and breezy conditions at times..
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New outline of the Tornado Watch. This is in effect until 4AM Friday Morning. It will be an active evening and overnight. Our KETK Weather Team will be keeping you safe. The Tornado warning for Northern Hopkins county is in effect until 9:15PM.
Counties included: Camp, Cass, Cherokee, Franklin, Gregg, Harrison, Henderson, Hopkins, Marion, Morris, Rains, Rusk, Smith, Titus, Upshur, Van Zandt, and Wood. This watch is in effect until 4AM Friday Morning.
Our first tornado warning for East Texas is for Northern Hopkins county until 9:15PM. This does not include Sulphur Springs.
We're checking with the NWS to see if the Tornado Watch will expire at 9PM or if the watch will be extended in time. We'll keep you updated.
Here in East Texas, we remain quiet. Storms are severe back to the West. We are still expecting them to move in by the mid-evening (between 8-10pm). There have been some tornado warnings earlier this afternoon and early evening. We are still under a Tornado Watch until 9PM.
This is something we'll be monitoring throughout the evening. As the sun sets tonight, our severe potential will weaken a little, but there will still be a tornado threat.
Keep you posted.
A Tornado Watch has been issued for most East Texas counties. Counties included: Anderson, Camp, Cass, Cherokee, Franklin, Gregg, Harrison, Henderson, Hopkins, Marion, Morris, Rains, Rusk, Smith, Titus, Upshur, Van Zandt, and Wood. This watch is in effect until 9PM tonight.
The latest timing on the storms moving through our area will be late this afternoon and into the evening hours.
Thursday Afternoon Update:
We are noticing that the dryline is a slow mover this morning toward Central Texas. However, by this afternoon and evening, we will be expecting showers and storms to intensify.
Here is the latest information:
The dryline was focused between Abilene and Lubbock. For our area, we remain in a very moist and warm environment.
Here in East Texas, we are under a mostly cloudy sky. We will see those clouds break by this afternoon and that will lead to showers and storms by the afternoon and evening.
Temperatures remaining very warm it has been windy. There is plenty of moisture and wind for storms to develop and get going this afternoon.
Storms won't initiate until the dryline moves closer to the Metroplex. When that happens, storms will become more likely. The High Resolution Rapid Refresh model is showing convection beginning by the mid-afternoon and continuing into the evening hours.
Again, we have been talking about a CAP aloft. A CAP means that there is a layer of warmer air closing off storms from initiating higher up into the atmosphere. This is a good thing to have a CAP, it keeps storms from developing. But, forcing will remove this CAP. Our forcing mechanisms are the dryline, upper level spin in the atmosphere, and the surface cold front. These are the factors that we will be monitoring over the next several hours.
Here are the severe weather threats for the afternoon and evening. Note that a tornado threat is present do to very strong winds at the surface and above our heads.
We'll be keeping you posted throughout the afternoon.
Wednesday Afternoon Update
Today, we have had area showers across East Texas. Most of the severe weather activity will be focused to the north and west of our area this evening and tonight.
Tomorrow, the entire KETK viewing area is under a risk of seeing some severe weather during the afternoon and evening as a cold front approaches us.
In this post, I’ll explain the setup, the timing of storms based off latest model data, and our severe weather threats for tomorrow.
This system has more upper level dynamics than our severe weather last week; and that means that our risk of severe weather increases. More widespread severe weather will be focused in Arkansas, extreme portions of Louisiana, and Missouri.
There will be an upper level trough at 500 millibars (or 18,000 feet) that will be moving through our area. On Thursday morning, it will be neutrally tilted (meaning straight up and down).
But as Thursday afternoon approaches, the trough becomes negatively tilted. What this means is that the wind speeds are increasing, causing height falls and increasing the severe weather potential. Where the upper level winds increase in speed (north of East Texas), that is where the severe weather will be more likely (increased risk of tornadoes). For East Texas, we will have strong winds at the surface and at 5,000 feet—still giving us a risk of some isolated tornadoes as well.
For our area, we’ll still have a chance of some supercell storms develop over our area. Our driving mechanism for storms on Thursday will be the dryline that will be to the West of DFW tomorrow morning. It is possible to have some morning showers across the area, but the best time will be in the afternoon and early evening hours as the dryline moves toward our area. Remember, a dryline is a separation of two airmasses—hot & dry (west) and warm & moist (east). Here is the NAM guidance of the dewpoints through the day; note the high dewpoints for our area (upper 60s to near 70)—it will be very moist here tomorrow.
As this dryline moves East tomorrow, it is possible to receive some daytime heating of the sun and this will break the CAP in the atmosphere, allowing for storms to develop. The NAM model at 1PM has the CAP breaking with CAPE values increasing by the afternoon and evening. Our RPM model shows the same.
The final parameter we will look at is the forcing for this event—also known as the vorticity. Vorticity is simply spin in the atmosphere. The main vorticity line will be staying to our north. However, out ahead of the main line, there will be some vorticity moving over our area, which will aid in the thunderstorm development over East Texas by Thursday afternoon. If the vorticity were to be closer to us, we would be dealing with a greater risk of tornadoes for tomorrow.
For this evening and tonight, you can expect muggy and humid conditions. A mostly cloudy sky for us means that this evening will remain in the 70s for the entire area. There could be a few isolated showers or a storm this evening, but the chance is about 20%. Tonight will also remain breezy for East Texas. Winds will be between 10-20 miles per hour with some gusts at times near 25 miles per hour. By tomorrow morning, we’ll wake up to morning lows in the upper 60s and low 70s. Here is the NAM at 10PM tonight, and 7AM tomorrow morning.
Similar to previous mornings, there will be some areas of fog. That fog will burn off by late morning. I believe that we will see some breaks in the clouds, which will aid in storm development. Temperatures by 1PM will be in the upper 70s and even some low 80s are quite possible. Tomorrow will be a windy afternoon too.
Storms will begin to fire up by the afternoon and into the evening. I will show you the GFS, NAM, and RPM models.
The GFS shows scattered convection increasing through the afternoon and evening.
The NAM model indicated storms in our area by the early afternoon and continuing through the late afternoon/early evening.
The RPM model depicts a quiet early afternoon with storms developing by the late afternoon and to the early evening.
The biggest factor will be the forcing of the surface dryline surging toward East Texas and the upper level trough. As these move for us, storms will likely fire up more than the computer models are indicating. This will mean storms will have the potential for very strong damaging winds, large hail, and isolated tornadoes.
Because the dynamical strength of this system, I think ALL East Texans need to be weather aware and ready for tomorrow. Review your plans of safety and be ready to act once a warning is issued. Timing will be from early Thursday afternoon and through Thursday evening—once the cold front will begin to push into the region.
The GFS and NAM are in agreement that the cold front won’t approach East Texas until late Thursday night and early Friday morning.
By daybreak Friday, the cold front will be through all of East Texas and it will be a much cooler and breezy day with sunny skies.
This forecast of severe weather will likely be changing. As we get new model data, we will have a better understanding of the timing of the severe storms. The biggest concern will be if the CAP will break, allowing the warmer air to not rise higher into the atmosphere. Our KETK Weather Team will be keeping you informed with the latest forecast on-air, right here at KETKnbc.com, via Social Media, and through our KETK Mobile App. For the latest forecast, visit the Weather page.