Texas Spring-2015

[Shoshana]

NWS Fort Worth is back up. Edit: and it's back down again.

It's region wide. NWS San Antonio /Austin has been down too

[Texas Snowman]

McCauley has mentioned on his Facebook page the role that outflow boundaries may play in potential tornadic storms tonight in/around DFW.

Passed through Jarrell over the weekend, reminded me of that terrible tornado and how an outflow boundary played a key role in the disaster that unfolded that day:

"The presence of an outflow boundary and its interaction with the cold front was an important mesoscale feature with significant implications."

http://www.aos.wisc.edu/uwaosjournal/Vo ... kowski.pdf

[TarrantWx]

Our OFB has formed. You can see it on the FWS reflectivity loop. It's laying across southern Wise, through Denton county, northern Collin county and up east of Sherman. The precipitation developing along and north of it might actually contaminate the environment though and decrease the available instability this afternoon.

http://radar.weather.gov/radar.php?rid=FWS&product=N0R&overlay=11101111&loop=yes

[dhweather]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
1054 AM CDT WED APR 22 2015

.UPDATE...
AN OUTFLOW BOUNDARY FROM MORNING CONVECTION IN OKLAHOMA WAS
ORIENTED NEAR A LINE FROM GRAHAM TO DENTON TO BONHAM AT 1045 AM.
THIS BOUNDARY WILL MOST LIKELY BECOME THE INITIATION POINT FOR
STORMS DUE TO CONTINUED LOW LEVEL MOISTURE CONVERGENCE. THE ONLY
LIMITING FACTORS FOR EARLY AFTERNOON CONVECTION WILL BE EXTENSIVE
CLOUD COVER ASSOCIATED WITH THE MORNING STORM COMPLEX IN OKLAHOMA
AND A LINGERING CAP. HOWEVER...THE CAP CONTINUES TO WEAKEN AND
SOME CLEARING IS MOVING SOUTHEAST FROM OKLAHOMA IN THE WAKE OF THE
OUTFLOW. WE WILL BE LAUNCHING AN 18Z SOUNDING TO ASSESS THE CAP
STRENGTH AND INSTABILITY. OUR BEST ESTIMATE IS THAT STORMS WILL
INTENSIFY BY MID AFTERNOON GENERALLY NORTH OF THE INTERSTATE 20
CORRIDOR ALONG THE OUTFLOW BOUNDARY. WILL ALSO BE MONITORING THE
SOUTHERN ZONES FOR ISOLATED CONVECTION WHERE SUN HAS BEEN MORE
ABUNDANT THIS MORNING AND THE CAP IS NEARLY GONE.

WILL MAKE NO MAJOR CHANGES TO THE CURRENT FORECAST PACKAGE OTHER
THAN TO UPDATE SHORT TERM CLOUD COVER...TEMP AND WIND TRENDS.

79

[Texas Snowman]

Sun is already shining again here in Denison after a 20 to 30-minute rainstorm an hour ago.

[TheProfessor]

still cloudy here in Southern Denton County, but Accurate weather is showing the clouds to be thin with gaps where the sun breaks through, it looks like the thick clouds from Oklahoma will mist most of the metroplex.

[Texas Snowman]

Hmmm.

From Larry Cosgrove, eight minutes ago on his Facebook page:

"After looking at the latest computer model forecasts, all that needs to be said is...

....prayers for North Texas, southern Arkansas, northern Louisiana, plus northern and central Mississippi. If you are into severe weather, start your engines."

Then he added, in response to someone's question about where and when, "This will be ugly, trust me..."

[TheProfessor]

McCauley has mentioned on his Facebook page the role that outflow boundaries may play in potential tornadic storms tonight in/around DFW.

Passed through Jarrell over the weekend, reminded me of that terrible tornado and how an outflow boundary played a key role in the disaster that unfolded that day:

"The presence of an outflow boundary and its interaction with the cold front was an important mesoscale feature with significant implications."

http://www.aos.wisc.edu/uwaosjournal/Vo ... kowski.pdf

Another thing about that Jarrell Tornado is that it is thought that the southwest movement of the storm may have aided the rapid intensification of the tornado because of the different direction of the winds.

[TheProfessor]

Hmmm.

From Larry Cosgrove, eight minutes ago on his Facebook page:

"After looking at the latest computer model forecasts, all that needs to be said is...

....prayers for North Texas, southern Arkansas, northern Louisiana, plus northern and central Mississippi. If you are into severe weather, start your engines."

Then he added, in response to someone's question about where and when, "This will be ugly, trust me..."

Hmm... is that for today or later this week, I'm hearing Friday could be pretty bad over a large area.

[Texas Snowman]

Both.

EDIT: Someone asked him if he was "buggin'" and he said no. Then he referenced models. Someone asked which ones. He responded: "All of them that I have seen so far. Try the NAM, GFS and RGEM for starters." Then posted a few maps in support.

[dhweather]

Hmmm.

From Larry Cosgrove, eight minutes ago on his Facebook page:

"After looking at the latest computer model forecasts, all that needs to be said is...

....prayers for North Texas, southern Arkansas, northern Louisiana, plus northern and central Mississippi. If you are into severe weather, start your engines."

Then he added, in response to someone's question about where and when, "This will be ugly, trust me..."

Seems a bit dramatic? I do not envision one PDS watch being issued today. Sure there will likely be severe weather, but that seems like he is adding hype in. Maybe its just me.

[Texas Snowman]

Cosgrove also adds something that Ntxw (I think) has alluded to, that this active pattern should continue for a while:

" the UVV, instability, and forward motion with the subtropical jet stream is really impressive. If the CFS is correct this carries on into middle or late May...."

[Texas Snowman]

Hmmm.

From Larry Cosgrove, eight minutes ago on his Facebook page:

"After looking at the latest computer model forecasts, all that needs to be said is...

....prayers for North Texas, southern Arkansas, northern Louisiana, plus northern and central Mississippi. If you are into severe weather, start your engines."

Then he added, in response to someone's question about where and when, "This will be ugly, trust me..."

Seems a bit dramatic? I do not envision one PDS watch being issued today. Sure there will likely be severe weather, but that seems like he is adding hype in. Maybe its just me.

I agree, that was my first thought. Don't see this as a PDS watch or high risk day unfolding.

But TarrantWx pointed out earlier "However, the slight days are usually the ones that overproduce whereas the moderate days normally bust, so we'll see."

I've noticed that too. In fact, the Jarrell tornado I referenced earlier this morning wasn't on a day when something of that magnitude was supposed to be in play. And yet that day produced the killer F5 in Jarrell and three other significant tornadoes that same day (the F3 north of Belton, the F3 in Cedar Park and the F4 in Lakeway).

[TarrantWx]

NWS Fort Worth ‏@NWSFortWorth 44s45 seconds ago
1126 AM: Unfortunately we were unable to get a special sounding due to equipment issues #txwx

[Texas Snowman]

With what's happened in Oklahoma two or three times since 1999 and the April 27, 2011 outbreak to our east, I think I've kind of been mentally conditioned to look for those "tornado swarm" kind of days.

If it's not that - a memorable swarm day - it's not that big of a deal. And I'm a weather geek.

And yet when I go back and look at the history of Texas and Oklahoma tornadoes (especially killer, or significant ones), those seem to often occur outside those kind of days. (Moore and El Reno being exceptions).

I'm not going to criticize the NWS' new system just yet because it may be spot on, but just looking at my Facebook page and gauging reaction from that, not too many people are mentioning the weather and its potential severity later in the day. That kind of has me concerned.

[dhweather]

Certainly psyche plays a role in all of this. Most people downplay "slight risk" as basically nothing. If I remember correctly, the 2012 Tornado outbreak, including the one in Forney, was on a "slight risk" day?

So I googled that event, April 3, 2012, this will get your attention:

The April 3, 2012 tornado outbreak was a small, albeit localized tornado outbreak that primarily affected the Dallas–Fort Worth metroplex.[2] During the morning of April 3, a large low-pressure area and associated frontal boundaries tracked across the Southern US Plains. Initially, environmental conditions did not favor the development of tornadoes. However, an outflow boundary from an area of storms in Oklahoma moved southwards before stalling over the Dallas–Fort Worth area. This allowed the formation of individual supercells, which would produce numerous tornadoes in the region. Many of these tornadoes occurred in the afternoon and evening hours of the day. One of these tornadoes was an EF3 tornado which struck areas of Forney, Texas, damaging homes and businesses; this tornado would be the strongest confirmed during the outbreak. However, the costliest tornado was of EF2 intensity, and struck the counties of Ellis and Dallas, causing roughly $400 million in damages. The same tornado also injured 10 people, but did not cause any damage. Throughout the duration of the outbreak, there were 22 confirmed tornadoes, though 17 of them were rated EF0 – the lowest rating on the Enhanced Fujita Scale.

A low pressure system and associated frontal boundaries tracked across the Southern Plains on April 3. The large-scale synoptics were marginal for tornadoes, hence only a slight risk of severe weather was issued by the Storm Prediction Center in Norman, Oklahoma, with large hail the primary threat and tornadoes and damaging winds secondary threats.[4] As a result of the initially perceived low risk, only a severe thunderstorm watch was initially issued for the region at 9:20 am CDT (1420 UTC


source: http://en.wikipedia.org/wiki/April_3,_2 ... o_outbreak

[iorange55]

Man, tracking winter storms is so much more fun. This is why I try to avoid the site during severe weather season. I mean, I do enjoy a nice storm, but not the ones carrying killer tornadoes.

Give me some lightning, 60mph winds, and I'll be just fine.

[TarrantWx]

Certainly psyche plays a role in all of this. Most people downplay "slight risk" as basically nothing. If I remember correctly, the 2012 Tornado outbreak, including the one in Forney, was on a "slight risk" day?

So I googled that event, April 3, 2012, this will get your attention:

The April 3, 2012 tornado outbreak was a small, albeit localized tornado outbreak that primarily affected the Dallas–Fort Worth metroplex.[2] During the morning of April 3, a large low-pressure area and associated frontal boundaries tracked across the Southern US Plains. Initially, environmental conditions did not favor the development of tornadoes. However, an outflow boundary from an area of storms in Oklahoma moved southwards before stalling over the Dallas–Fort Worth area. This allowed the formation of individual supercells, which would produce numerous tornadoes in the region. Many of these tornadoes occurred in the afternoon and evening hours of the day. One of these tornadoes was an EF3 tornado which struck areas of Forney, Texas, damaging homes and businesses; this tornado would be the strongest confirmed during the outbreak. However, the costliest tornado was of EF2 intensity, and struck the counties of Ellis and Dallas, causing roughly $400 million in damages. The same tornado also injured 10 people, but did not cause any damage. Throughout the duration of the outbreak, there were 22 confirmed tornadoes, though 17 of them were rated EF0 – the lowest rating on the Enhanced Fujita Scale.

A low pressure system and associated frontal boundaries tracked across the Southern Plains on April 3. The large-scale synoptics were marginal for tornadoes, hence only a slight risk of severe weather was issued by the Storm Prediction Center in Norman, Oklahoma, with large hail the primary threat and tornadoes and damaging winds secondary threats.[4] As a result of the initially perceived low risk, only a severe thunderstorm watch was initially issued for the region at 9:20 am CDT (1420 UTC


source: http://en.wikipedia.org/wiki/April_3,_2 ... o_outbreak

This has had me concerned all day. I initially thought to myself this feel somewhat like the 2012 day. The OFB is clearly defined on radar and visible satellite now. And if I'm not crazy it looks like there's another boundary on satellite in SW OK. Unfortunately there seems to be a high potential for OFB interaction today and that's never a good thing.

[gboudx]

IIRC that was also the tornado that tracked from Forney across Kaufman, into Rockwall county and hit parts of Royse City, Fate and Greenville. Days later we went for a ride along Hwy 276 and saw debris scattered all over the place.

[TarrantWx]

I'm also growing concerned about not only supercell/OFB interaction but a potential bow echo/derecho type MCS event overnight from upscale growth of supercells over SW OK and NW TX if the environment goes untapped.