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Rain Chances Looking Up!

Rain totals through 6 PM Monday, February 11

Rain totals through 6 PM Monday, February 11

This graphic comes from the Hydrometeorological Prediction Center and shows the expected rainfall totals for the next 7 days. As you can see by all the greens, blues, and purples, the chance of rain is going up! Like it has been for months now, the highest rainfall totals look to be along and east of Interstate 35. However, current data does show that rain will also likely occur west of Interstate 35 as well.

These rain chances are due to a series of storm systems that will move across Texas over the next few days. One of these systems will pass over on Wednesday and Thursday with a stronger storm system expected by the weekend. The weekend storm system could even bring stronger thunderstorms with it. We’re way too far out to worry about that possibility though.

nam_48hr_precip_tx_27Our Wednesday storm system will bring the highest chances of rain to areas near and south of Interstate 10 from San Antonio into Louisiana. Rainfall amounts will average half to three-quarters of an inch with isolated higher amounts possible. The rain chances will spread northward by Wednesday night into Thursday with accumulation amounts between a tenth of an inch and half an inch further north. Severe weather isn’t expected to be a big issue, but we will have to watch the Rio Grande Valley for a chance of stronger storms.

gfs_z500_uv_vort_west_45A stronger storm system looks to affect Texas by the weekend with the possibility of several days of rain and storm chances. We’re still quite a ways out so model guidance is still showing all sorts of different solutions. This system could bring beneficial rainfall and a chance of strong storms. We’ll have more on this system once we get past our Wednesday/Thursday storm.

 

 

New Outlook: Severe Risk for Today Expanded

National Severe Weather Outlook

National Severe Weather Outlook

The Storm Prediction Center just released their brand new severe weather outlook for today. The standard risk of severe weather has been expanded further south and west. This risk now includes the Houston and Austin metro areas, in addition to areas of Central and Southeast Texas that were not in it yesterday. The elevated risk of severe weather, where we expect more widespread severe weather, has been expanded to the west and now includes the eastern half of the D/FW Metropelex and all of Northeast and East Texas. Extreme Northeast Texas has been added to the significant risk of severe weather, which is not a good place to be. The significant risk of severe weather is where we have the most concern above very damaging straight-line winds and a higher tornado threat.

For an easy to read review of the threat in the risk areas. Please don’t nitpick on your exact area. Thunderstorms don’t care about graphics and outlooks. If you’re in or close to a risk area, keep up with the weather later on this morning into the afternoon.

Standard Severe Weather Risk

  • Nickel to Quarter size hail
  • 60+ MPH straight-line winds

Elevated Severe Weather Risk

  • Nickel to Quarter size hail
  • 70+ MPH straight-line winds
  • Isolated tornado threat (secondary threat)

Significant Severe Weather Risk

  • Nickel to Quarter size hail
  • 75-80+ MPH straight-line winds
  • Strong, Long-Track Tornadoes
Texas Severe Weather Outlook

Texas Severe Weather Outlook

How Tornado Damage is Rated

After a tornado hits, storm damage survey teams are deployed by the local National Weather Service office to survey and document the types of damage found.  Only after careful analysis and application of the EF Scale assessment process is a rating given to the damage caused by the tornado.  It’s the amount of damage that determines the rating and also provides an estimate of wind speeds.

Below is an outline of the EF Scale damage assessment process provided by the Storm Prediction Center.  The 28 Damage Indicators can be viewed by clicking on the blue text.

When using the EF-Scale to determine the tornado’s EF-rating, begin with the 28 Damage Indicators. Each one of these indicators have a description of the typical construction for that category of indicator. Then, the next step is to find the Degree of Damage (DOD). Each DOD in each category is given and expected estimate of wind speed, a lower bound of wind speed and an upper bound of wind speed.

Let’s take the earlier example, a tornado moves through a neighborhood and walls are knocked down of an area of homes. Here the Damage indicator would be #2, One or Two Family Residences (FR12). The typical construction for this fits being a brick veneer siding home. The DOD would be a 8, most walls collapsed in bottom floor. Thus, the estimated winds would be 127 – 178 mph with the expected wind speed of 152 mph. Now, taking this number to the EF-Scale, the damage would be rated EF-3 with winds between 136 – 165 mph.

Enhanced Fujita Scale

Enhanced Fujita Scale

At the following link, you can find some interesting pictures as an example of each degree of damage.  Just click the underlined hyperlinks in the “Typical Damage” column.  http://www.spc.noaa.gov/faq/tornado/f-scale.html

 

 

Possible Christmas Snow Storm – Friday Evening Update

Highlights

  • Confidence in a Cold Air Outbreak in Texas by Christmas Afternoon is high
  • Confidence in light snow occurring in Texas is moderate.
  • Confidence WHERE in Texas snow will fall is low.
  • Confidence in accumulating snowfall in Texas is low.
  • We will begin to get better weather model consistency on Saturday, at least that is the hope.

Discussion

We’ve been talking about it since last weekend, but even now we still have a great deal of uncertainty about the possible Christmas winter storm. We are confident that there will be another cold air outbreak that will make temperatures quite chilly by Christmas evening (sooner in northern parts of Texas) with some rain possible on Christmas Eve along and east of Interstate 35. By Christmas morning, cooler air will be filtering into Texas. That will allow rain to change over to snow in portions of the Texas Panhandle, Northwest Texas, North Texas, and Northeast Texas. Exactly where the rain/snow line sets up is debatable, but certainly not exactly predictable. Remember, we’re still over 84 hours out from this potential event. This storm has not yet made it into the United States Upper Air Network nor has the system entered the range of our high-resolution weather models. Everything you see below will change at least once over the weekend, so be sure to check back for updates. I plan to release my own personal thoughts on the Christmas Event once we get into Saturday and we receive more data about the system. For now, I’m going to post the forecast graphics from several of the National Weather Service offices in the affected regions.

Graphics

NWS Amarillo

NWS Amarillo

NWS Norman/Oklahoma City

NWS Norman/Oklahoma City

NWS Fort Worth

NWS Fort Worth

NWS Tulsa

NWS Tulsa

NWS Shreveport

NWS Shreveport

Spring-like Temperatures for Today

Temperatures are cooler this morning than they have been the past few days, but are near their seasonal averages. That means a coat would be a good item to have as you head out. Don’t let the cool morning deceive you, temperatures across the state will quickly warm into the 60s and 70s by noon. Temperatures will be warmest in the Valley and South Texas with highs topping above 80 degrees. Further north, temperatures will range from 68 to 75 degrees. The Texas Panhandle will be a bit cooler with high temperatures topping out in the upper 50s.

Winds will be calmer today state-wide, especially in West Texas where they had issues with dust on Monday. The respite will be short-lived as winds pick up again overnight tonight and especially on Wednesday. A rather high-impact wind event is possible in West Texas on Wednesday with widespread blowing dust. No rain is expected anywhere in Texas today.

We’ll have more on Wednesday’s issues with our afternoon discussion along with more on next week’s potential Christmas storm. I’ll leave you with the temperature forecast for your specific area. Have a good Tuesday!

7 AM Temperatures

7 AM Temperatures

12 PM Temperatures

12 PM Temperatures

4 PM & High Temperatures

4 PM & High Temperatures

9 PM Temperatures

9 PM Temperatures

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