Watching the Skies » Flash Flood Warning

West Dallas tornado rated eF-2, six other tornadoes around north Texas

Sean Toner — Thu, 09 Sep 2010 22:59:39 +0000

Tornado damage consistent with an eF-2 tornado was found in West Dallas during a storm survey conducted by the National Weather Service today. The tornado’s path was one half mile in length, causing significant damage to numerous structures in that area. A preliminary track map shows it crossing the Trinity River and its levees, which should debunk any myths people may of had about tornadoes and river crossings… (source: http://www.srh.noaa.gov/fwd/?n=prelimtrackmap) I have included a tornado damage summary provided by the National Weather Service below.

Six other tornadoes were documented around the area, including another which caused moderate damage in southeast Dallas county, to the city of Seagoville. Below is radar snaps of the storm as it looked while producing the tornado in West Dallas. The storm is not overly impressive, when compared to supercells during our spring time severe weather season, but still displays the traditional hook echo and velocity couplet associated with tornadic supercells.

A similar feature is observed with the northeast Ellis/southeast Dallas counties tornado. A noteworthy hook echo and velocity couplet are observed by radar.

Thankfully the next 7 days don’t appear to show any significant tornado threats. Forecast models show marginal chances of thunderstorms Friday night, but I wouldn’t bet on it. Additionally a weak front may move through the area Saturday, then lay stationary across the Metroplex Sunday into Monday. This front has the potential to kick off organized severe development along and to the south of the front, but coverage of storms may be limited. Regardless I would consider storms a possibility Saturday and Sunday. Straight line winds and hail would be possible with stronger storms over the weekend, but the tornado threat will be minimal as environmental wind shearing will be very low. Temps the next 7 days will remain above normal and with high dew points due to the obvious abundance of moisture, our heat indexes will be around 100 to 105.

It would seem summer has not quite left us yet.

Tornado damage survey report by the NWS:

…PRELIMINARY DAMAGE REPORT…

A TOTAL OF SIX TORNADOES OCCURRED ON WEDNESDAY SEPTEMBER 8TH. FOUR
TORNADOES WERE RATED EF0 ON THE ENHANCED FUJITA SCALE. ONE TORNADO
WAS RATED EF1…AND ONE TORNADO WAS PRELIMINARILY RATED EF2. ONLY
TWO MINOR INJURIES HAVE BEEN REPORTED FROM ALL OF THESE STORMS.

THE EF2 TORNADO DAMAGE WAS LOCATED IN THE CITY OF DALLAS NEAR THE
INTERSECTION OF MOCKINGBIRD LANE AND IRVING BOULEVARD. THIS
TORNADO CAUSED MINOR ROOF DAMAGE TO SEVERAL BUILDINGS AND CAUSED
MORE EXTENSIVE DAMAGE TO A WAREHOUSE. AN EXTERIOR NON LOAD BEARING
WALL COLLAPSED…LEADING TO A PARTIAL COLLAPSE OF THE ROOF. THIS
DAMAGE WAS RATED EF2 ON THE ENHANCED FUJITA SCALE WITH WIND SPEEDS
OF APPROXIMATELY 115 MPH. THE LAST TIME THE CITY OF DALLAS HAD A
TORNADO RATED AT F2/EF2 OR HIGHER WAS F2 TORNADO DAMAGE ON APRIL
11 1974. THE LANCASTER TORNADO OF APRIL 25 1994 PRODUCED F4 DAMAGE
IN THE CITY OF LANCASTER BEFORE DISSIPATING WITHIN THE CITY LIMITS
OF DALLAS.

THE EF1 TORNADO DAMAGE WAS LOCATED IN THE CITY OF SEAGOVILLE JUST
EAST OF HIGHWAY 175. AT LEAST THREE APARTMENT BUILDINGS SUFFERED
SIGNIFICANT ROOF DAMAGE. WIND SPEEDS IN THIS TORNADO ARE ESTIMATED
TO BE NEAR 90 MPH.

THE REMAINING TORNADO DAMAGE WAS GIVEN A PRELIMINARY RATING OF
EF0. THESE TORNADOES OCCURRED NEAR LINDSAY IN COOKE COUNTY…NEAR
FERRIS IN ELLIS COUNTY…IN HEATH IN ROCKWALL COUNTY…AND NEAR
BLOSSOM IN LAMAR COUNTY.

THE ENHANCED FUJITA SCALE RATES TORNADO DAMAGE.

ENHANCED FUJITA SCALE APPROXIMATE WIND SPEED RANGE

EF0 65-85 MPH
EF1 86-110 MPH
EF2 111-135 MPH
EF3 136-165 MPH
EF4 166-200 MPH
EF5 200 MPH OR GREATER

Tropical Storm Hermine & it’s effects

Sean Toner — Thu, 09 Sep 2010 02:08:59 +0000

Tropical Storm Hermine, a remarkably impactful storm for the DFW Metroplex which sits 550 miles north of the storm’s initial landfall. The storm has brought severe flooding to a 300 mile stretch of central and north Texas, along the I-35 corridor. The worst flood effects are being felt in San Antonio through Austin. Flash flooding has even occurred in the Metroplex, the most notable being numerous homes and trailers flooded in the cities of Lewisville, Arlington, and Fort Worth. The heavy rains brought over 12 inches of rain near Austin as of 8am today (9/8/10) and 4 to 6 inches of rain in the Metroplex. (source: CoCoRaHS) My CoCoRaHS gauge captured 4.01 inches of rain in the 24hr period from 8am 9/7/10 to 8am 9/8/10. Another several inches have been observed since that time, with even more rain on the way. Below is radar estimated total rainfall from the FWS dopplar radar. An even more accurate and complete picture region wide view is available from the National Weather Service at http://www.srh.noaa.gov/ridge2/RFC_Precip/.

As if the flooding rainfalls weren’t enough, Hermine brought the risk of tornadoes to the region with several damage reports in Dallas, Highland Park, Seagoville, Ferris and Trumbull. Tornadoes embedded within the outer rain bands of tropical systems aren’t uncommon to coastal regions in the Gulf, but it is fairly unusual to get those type of tornadic storms this far away from the Gulf. Tornadoes in this type of environment tend to develop without warning and are difficult to detect with current radar technology, but are very brief and usually weak. The Dallas Morning News reported ripped up roofs in Cockrell Hill, Oak Cliff, West Dallas, and the Love Field areas. (source: Dallas Morning News) A Tornado Warning was also issued for a storm 4 miles south of Hebron at 5:37pm. The warned area included Frisco, Plano, and The Colony. The storm showed rotation on radar, and storm spotters observed a rotating wall cloud within the storm. Thankfully no tornado damage has been reported with this storm. Its center of circulation traveled north along the Denton/Collin county line, passing over Highway 121 and Plano Parkway, then dissipating. I got the pleasure of evacuating to our work’s ‘shelter’ area which amasses to little more than an open hallway, without access to my computer with accurate radar data.

A Tornado Watch still remains in effect for the entire DFW Metroplex, southeastern Oklahoma and western Arkansas until 1am. Another rain band is approaching from the west, with an approximate ETA of around 11pm to midnight tonight to Frisco/Plano/The Colony. Rain chances will continue Thursday, however nowhere near the levels observed the past two days. Hot and humid conditions should be expected the remainder of the week and weekend as the sun comes out and starts evaporating the abundance of water on the ground.

Lastly ill end with a quote from the local weather forecast office regarding the heavy rains the last two days…

DFW AND WACO HAVE BOTH SET CALENDAR-DAY PRECIPITATION RECORDS TODAY (SEPT 8). FOR BOTH SITES…THE 24-HR TOTALS (SEPT 7-8) WILL RANK AMONG THE TOP 10 ALL-TIME. PRECISE NUMBERS WILL BE AVAILABLE THURSDAY MORNING.

AT THE PRESENT TIME…THIS MONTH WILL RANK AS THE 4TH WETTEST SEPTEMBER ON RECORD FOR BOTH DALLAS/FORT WORTH AND WACO.

Flash Flooding around the entire DFW Metroplex

Sean Toner — Wed, 08 Sep 2010 14:08:07 +0000

Hey group… its been awhile but the weather conditions today merit an email… By now we are all aware of the heavy rainfall affecting the region, but may not be immediately aware of the flash flooding occurring around the region. Right now, several flash flood reports have come in from the area, including Plano, Dallas, Fort Worth and Saginaw. Major intersections in Plano near the George Bush Turnpike are submerged, low water crossings in Dallas are under several feet of water, and intersections around Fort Worth are impassible due to water. All stations in the area show at least 3 inches of rain with some showing 6 to 7 inches in the last 24 hours, which easily surpasses the criteria needed for flash flooding conditions. Below is radar estimated total rainfall. You can see Fort Worth is showing a large swath of 7 to 8 inch estimates so far. Stay safe everyone, and do not attempt to drive into submerged intersections!

Flash Flooding across the Metroplex

Sean Toner — Thu, 22 Oct 2009 03:20:20 +0000

Several Flash Flood Warnings are issued for Tarrant, Denton, Collin, Grayson, Cooke and other counties around the area. A band of very heavy rainfall has fallen creating flooding conditions most notably around Fort Worth where several high water rescues have been taking place after motorists get stranded in high waters. Additionally the Trinity river at Dallas is surpassing flood stage at this time, and is forecast to exceed flood stage by 4 feet. At 34 feet several low water crossings will flood. This heavy rainfall will continue for a few more hours at least until the cold front passes through Thursday before sunrise. The rain will likely come to an end sometime around 3am to 5am I am thinking. Until then, plan for continuous heavy rain and flash flooding potential.

Here is the storm total rainfall amounts so far, this is since 1:21am Wednesday morning. Blue areas are reaching up to 5.8 inches of rainfall. The green polygons indicate current Flash Flood Warnings, the green and blue FFL icons indicate reports of Flash Flooding including road closures and high water rescues.

Flash Flooding around North Texas!

Sean Toner — Tue, 13 Oct 2009 15:15:26 +0000

A band of moderate to heavy rainfall is sitting stationary just south and east of the DFW Metroplex, prompting Flash Flood Warnings and even a high water rescue in the city of Terrell. Rain totals in these areas since 6 pm Monday are around 2.25 inches estimated, showing that the soil is so heavily saturated and unable to absorb any more rainfall.

Below is radar estimated rainfall since 6pm Monday, you can easily see the areas where rainfall is most concentrated… the Green FFL icons indicate reports of Flash Flooding, the green polygons show current Flash Flood Warnings.

Saturday’s severe weather summary

Sean Toner — Sun, 03 May 2009 06:20:01 +0000

Wow, well today was one of the more wild weather day’s Ive experienced! I counted a total of 4 Severe Thunderstorm Warnings and 2 Flash Flood Warnings for both Collin and Denton counties. Then there was the one Tornado Warning for extreme south east Collin county which set off the sirens here which was pretty stupid (youll see why below). Numerous storm reports came in of all types, very high winds up to 70mph, hail up to 1.75 inches, flooding into houses, covering streets under 2 feet of water, and even one tornado report in Greenville 35 miles east of Frisco. One of the more notable damage reports that I am sure most have heard of is the collapse of the training building the Dallas Cowboys were using. According to myfoxdfw.com , 12 people were injured during the collapse though none of them are life threatening. The NWS has performed a damage survey already and determined this was due to a microburst and not a tornado. Details below:

…RESULTS OF VALLEY RANCH DAMAGE SURVEY…

BASED ON A SURVEY OF THE ON-SITE DAMAGE…RADAR IMAGERY…AND
EYEWITNESS REPORTS…THE NATIONAL WEATHER SERVICE DETERMINED THAT
A MICROBURST IMPACTED THE VALLEY RANCH AREA OF FAR NORTH IRVING.
MAXIMUM WINDS NEAR THE GROUND WERE ESTIMATED NEAR 70 MPH.

RESEARCH HAS INDICATED THAT WIND SPEEDS IN HIGH WIND EVENTS OFTEN
INCREASE CONSIDERABLY IN THE LOWEST FEW HUNDRED FEET ABOVE THE
GROUND. THEREFORE…IT IS QUITE POSSIBLE THAT WINDS GREATER THAN
70 MPH AFFECTED THE UPPER PORTIONS OF THE DAMAGED STRUCTURES.

A MICROBURST IS A SMALL…INTENSE DOWNDRAFT WHICH RESULTS IN A
LOCALIZED AREA OF STRONG THUNDERSTORM WINDS. IN EXTREME CASES…
MICROBURSTS CAN HAVE WINDS WHICH EXCEED 100 MPH.

Today, a total of 1 tornado report in Greenville, 22 hail reports including 3 reports of golfball size (1.75 inch), 18 high wind reports including damage, and 14 flood reports in the Fort Worth forecast area, most of these are in the immediate metroplex. This totals 55 severe weather reports for this area alone!

Additionally, the metroplex has received a substantial ammount of rain in the past 7 days. Today a very healthy part of Dallas and Fort Worth received 3.5 inches or higher, including Frisco. Just 9 miles NW of Frisco, or 3 miles NW of Little Elm, radar estimates a total of 9 inches of rainfall fell today! Below is the radar estimated rainfall.

Here is a screenshot of the locations of all the storm reports that came in. Green FFL and FLD mean Flash Flood/Flood. Green icons with 3 blue circles mean hail. Yellow icons mean wind or wind damage. The red icon is a funnel cloud icon.

Now, allow me to show you a fantastic example of why tornado sirens should not be your primary source of tornado notification. So I am sure most of us heard the sirens sound today. Well, in the screenshot below, you can see where the tornado warning is actually issued for. Its a whole 25 miles to our ESE and the storm is not moving twards us. This is exactly why you cannot trust tornado sirens. Yes, the weather radios did go off for us too, those are limited to county by county notification, so technically since Collin was within the warning box, the radios went off for us. However, the warning text did say south east Collin county, which is definately not where Frisco is.

Guess I have sent out a total of 17 e-mails today, including this one… So umm.. If you dont like the spam then sorry, let me know lol. Today was pretty wild though!

Flash Flood Warning for Denton County TX

Sean Toner — Sun, 03 May 2009 00:27:16 +0000

Denton county got jelous of Collin county’s Flash Flood Warning, so it joined in too… see previous flash flood email for the radar estimated total. This mainly concerns areas around Denton, but the entire county is warned currently.

The National Weather Service in Fort Worth has issued a
* Flash Flood Warning for… Denton County in north central Texas
* until 1030 PM CDT
* at 723 PM CDT…National Weather Service meteorologists detected thunderstorms with heavy rain along a line extending from Hackberry to 3 miles west of Justin…moving northeast at 20 mph. Radar indicates that 1 to 2 inches of rain has already fallen. Another 1 to 2 inches will be possible through 1030 PM CDT.

* Locations that will continue to be affected by heavy rain include…Little Elm…Corinth…Shady Shores…Krum…Denton… Cross Roads…Sanger…Krugerville…Aubrey…ray Roberts Park Isle Du Bois and Pilot Point.

Precautionary/preparedness actions…

Do not drive your vehicle into areas where water covers the Road to unknown depths. It only takes two feet of rushing water to carry awaymost sport utility vehicles and pickups. Take a different Route toreach your destination or wait until the water recedes. Remember…most flood related deaths occur in automobiles.

Flash Flood Warning for Collin County TX

Sean Toner — Sun, 03 May 2009 00:07:15 +0000

OK so now its official, our county has had every type of severe weather warning possible today. Weve had a few severe thunderstorm warnings including one ongoing now, a tornado warning in extreme south east Collin county, and now we have a Flash Flood Warning.

A majority of Frisco has received a radar estimated 1.25 to 1.75 inches of rain, with a speck of 2.25 inches near our area. The highest rainfall areas are in Denton, and Dallas, both of which are sitting around 3.5 inches of rain so far today.

BULLETIN – EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE FORT WORTH TX
658 PM CDT SAT MAY 2 2009

THE NATIONAL WEATHER SERVICE IN FORT WORTH HAS ISSUED A

* FLASH FLOOD WARNING FOR…
COLLIN COUNTY IN NORTH CENTRAL TEXAS
HUNT COUNTY IN NORTH CENTRAL TEXAS
KAUFMAN COUNTY IN NORTH CENTRAL TEXAS
ROCKWALL COUNTY IN NORTH CENTRAL TEXAS

* UNTIL 1100 PM CDT

* AT 656 PM CDT…NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED
A LARGE AREA OF VERY HEAVY RAIN MOVING INTO THE WARNED AREA.
THE HEAVIEST RAINS EXTENDED FROM NEAR MCKINNEY TO NEAR
CRANDALL… MOVING NORTHEAST AT 40 MPH. RADAR INDICATES THAT 1 TO
2 INCHES OF RAIN HAS ALREADY FALLEN FROM EARLIER THUNDERSTORMS.
ANOTHER 1 TO 2 INCHES WILL BE POSSIBLE THROUGH 1100 PM CDT.

* LOCATIONS THAT WILL CONTINUE TO BE AFFECTED BY HEAVY RAIN
INCLUDE…KEMP…CELINA…FAIRVIEW…FORNEY…MABANK…KAUFMAN…
HEATH…LUCAS…WYLIE…ROCKWALL…LOWRY CROSSING…PRINCETON…
TERRELL…FATE…ANNA…ROYSE CITY…FARMERSVILLE…CADDO MILLS…
QUINLAN…WEST TAWAKONI…CELESTE…GREENVILLE…WOLFE CITY…
CAMPBELL AND COMMERCE.

PRECAUTIONARY/PREPAREDNESS ACTIONS…

EXCESSIVE RUNOFF WILL CAUSE FLASH FLOODING OF SMALL CREEKS AND
STREAMS…HIGHWAYS AND UNDERPASSES. ADDITIONALLY…COUNTRY ROADS AND
FARMLAND ALONG THE BANKS OF CREEKS AND STREAMS AND OTHER LOW LYING
AREAS ARE SUBJECT TO FLASH FLOODING.