Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 7

[bubba hotep]

It looks like a lot hinges on how far east the line of storms pushes tonight. Models seem to often under do the of eastward propagation of N. Texas MCSs, so that may allow for heavier rain to get to or east of I35 late tonight.

 

[bubba hotep]

12z GFS & Euro are like 4"+ for everyone with pockets of 7" and other crazy totals.

And the 12z GFS is another run dropping nearly a foot of rain at DFW over the next two weeks.

[bubba hotep]

As expected, flood watch expanded to cover a large portion of Texas

 

[jm1220]

Already getting some mod-heavy showers where I am. 

[Quixotic1]

It's going to be interesting to see how this unfolds. We could stay pretty wet if the +PDO/ -AMO can take hold. Also, much like El Nino, there isn't really a standard La Nina with temps and precipitation being all over the place when you break out the individual years, esp during winter.

Yeah it's no gimme. However in recent years La Niña conditions have meant drought. The strong ones in particular tend to be dry. Secretly I think the cold air problem is solved.

[bubba hotep]

Yeah it's no gimme. However in recent years La Niña conditions have meant drought. The strong ones in particular tend to be dry. Secretly I think the cold air problem is solved.

 

It looks like the winters of '67-68, '83-84 and '00-01 were on the colder side for Texas with '67-68 and '00-01 being wetter than normal. Also, when I was looking into McFarland signatures, they almost exclusively occur during La Nina winters. I'll have to go back and look at that post and pull the data so that I can post it again in the thread next winter. 

[NTXYankee]

The lines at the grocery store by my house you'd think a snowstorm was coming.

[Quixotic1]

It looks like the winters of '67-68, '83-84 and '00-01 were on the colder side for Texas with '67-68 and '00-01 being wetter than normal. Also, when I was looking into McFarland signatures, they almost exclusively occur during La Nina winters. I'll have to go back and look at that post and pull the data so that I can post it again in the thread next winter.

I have to look up 67-68 but 83-84 was like the mother of all McFarland signatures - particularly December. 00-01 was spectacular from the end of November through the middle of January. The key takeaway being if it doesn't happen early, it ain't gonna happen. Anywho, ninas have a tendency towards better severe seasons as well. Change is good. Once the whip (jet stream) is cracked (strong Nino) all sorts of cool things are possible.

[bubba hotep]

HRRR continues to come in a bit faster with each run and the last run is kind of "bowish" looking as it moves the line towards DFW. 

[Roy]

HRRR continues to come in a bit faster with each run and the last run is kind of "bowish" looking as it moves the line towards DFW. 

 

Would that speed up the complex, reducing rainfall? It sure looks like a good rain event no matter what, just hopefully not too much of a good thing.

[jhamps10]

Severe storm watch out overnight for areas just west of i35 out towards Abilene..

[bubba hotep]

Looks like models are really backing off on the big rain event and are more like a couple of inches with a few areas of higher amounts around the DFW area. The hangup right now would be that the HRRR and 4k NAM have the current line dying off by now and then a second round of convection forming farther west and pushing into the area. Typically, ongoing convection SE of DFW eventually shuts things down for us. However, the orientation of the line is starting to change, so maybe it is losing the eastward push. That might allow for training cells to develop and that would certainly raise totals, pretty complex setup this morning.

 

ETA: Based on current SPC mesoanalysis, not seeing a lot of support for the line continuing its eastward push at current strength. So we may see it continue to fade and/or become stationary   

[jm1220]

East of here towards Bastrop getting nailed currently by training echos. 

 

This area in general looks to get its most sustained, heavy rain later today when more storms fire along the outflow boundaries generated yesterday, and the boundaries in general move south. Then the wild card is what happens late tomorrow and Tuesday. If that fires mostly to our east, this should be a manageable 2 or 3" rain event for this area. If we get nailed again tomorrow night and Tuesday, that's when we can get the 6"+ totals forecast for places east of here like College Station. 

[bubba hotep]

East of here towards Bastrop getting nailed currently by training echos. 

 

This area in general looks to get its most sustained, heavy rain later today when more storms fire along the outflow boundaries generated yesterday, and the boundaries in general move south. Then the wild card is what happens late tomorrow and Tuesday. If that fires mostly to our east, this should be a manageable 2 or 3" rain event for this area. If we get nailed again tomorrow night and Tuesday, that's when we can get the 6"+ totals forecast for places east of here like College Station. 

 

Yea, the 12z GFS points to a couple more rounds of heavy rain for areas of Texas. Looks like the jackpot on this run moved from areas SW of Houston to areas to the NW of Houston. 

 

ETA: 12z Euro is back to hammering DFW overnight and has many areas with another 4-6" of rain

[bubba hotep]

MESOSCALE PRECIPITATION DISCUSSION 0123
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
120 PM EDT SUN APR 17 2016

AREAS AFFECTED...PORTIONS OF CENTRAL AND EASTERN TX

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 171715Z - 172315Z

SUMMARY...SLOW-MOVING HEAVY SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO CONTINUE THIS AFTERNOON WITH REPEATING CELLS AND CELL-MERGERS
LIKELY. CONCERNS FOR FLASH FLOODING WILL INCREASE THROUGH THE
AFTERNOON.

DISCUSSION...MOIST AND RELATIVELY UNSTABLE LOW LEVEL FLOW
CONTINUES TO CONVERGE NORTH ACROSS CENTRAL AND SOUTHEAST TX AND
TOWARD WHAT HAS BEEN A PERSISTENT AXIS OF HEAVY SHOWERS AND
THUNDERSTORMS. THE COLDER CONVECTIVE TOPS OVER THE LAST HOUR HAVE
BEEN GENERALLY SOUTH OF DALLAS DOWN TOWARD THE WACO AND GATESVILLE
AREA. ADDITIONAL CELLS ARE ALSO DEVELOPING JUST SOUTHEAST OF
AUSTIN WHICH IS INDICATIVE OF ADDED BOUNDARY LAYER DESTABILIZATION
WITHIN THE BROAD AND DEEPER LAYER SOUTH TO SOUTHEAST FLOW ACROSS
SOUTHEAST TX.

OVER THE NEXT FEW HOURS THERE WILL BE STRONG CONCERNS FOR SOME
VERY HEAVY RAINFALL TOTALS AS INCREASED DIABATIC HEATING/SOLAR
INSOLATION AHEAD OF THE CONVECTION HELPS DESTABILIZE THE BOUNDARY
LAYER FURTHER. THIS IS SUGGESTED IN THE LATEST VIS SATELLITE
IMAGERY WHICH SHOWS AN EXPANSIVE CU/TCU FIELD SURGING NORTH TO
NORTHWEST ACROSS SOUTH TEXAS ALONG WITH A NUMBER OF CLOUD STREETS.
THIS WILL ALLOW CONVECTION TO CONTINUE TO FOCUS ALONG A
CONVECTIVELY ENHANCED OUTFLOW BOUNDARY...AND ALSO IN A SOMEWHAT
ELEVATED FASHION OVER A WELL-DEFINED COLD POOL OVER CENTRAL TX.

THE HIRES GUIDANCE HAS BEEN TERRIBLE IN ACCURATELY DEPICTING THE
CONVECTIVE EVOLUTION TODAY ACROSS THE REGION...BUT RECENT RUNS OF
THE HRRR/HRRX ARE SUGGESTING SOME IMPRESSIVE CONVECTIVE RAINS
DEVELOPING NEAR THE CURRENT OUTFLOW BOUNDARY THROUGH THE AFTERNOON
HOURS. THE 15Z HRRR-TLE INDICATES HIGH PROBABILITIES OF OVER 6
INCHES IN 6 HOURS GENERALLY WITHIN A LINE FROM WACO TO AUSTIN TO
LLANO.

PWATS ARE GENERALLY CLOSE TO 1.5 INCHES NOW ACROSS THIS
REGION...AND WITH RATHER STRONG SBCAPE VALUES SETTING UP SOUTH F
AUSTIN...CONVECTION SHOULD TEND TO INTENSIFY WITH HEAVIER RAINFALL
RATES THROUGH THE AFTERNOON. CURRENT RADAR TRENDS INDICATE A
LIKELIHOOD OF CELL-MERGERS...AND THIS WILL ENHANCE THE RATES
FURTHER.

EXPECT RAINFALL AMOUNTS OVER THE NEXT 6 HOURS TO BE AS MUCH AS 3
TO 6 INCHES WITH LOCALLY HEAVIER AMOUNTS PERHAPS APPROACHING 8
INCHES WHERE CELL-MERGERS AND REPEATING CELLS OCCUR. THE MEAN FLOW
IS NOT VERY KEEN ON A STRONG SOUTHEAST PUSH THIS AFTERNOON...SO
EXPECT NUMEROUS REPEATING CELLS TO FOSTER HEAVY RAINFALL TOTALS
WITH AN ENHANCED FLASH FLOOD THREAT.

ORRISON

[jm1220]

HRRR absolutely nails western Travis/Hays/Williamson/Bell Counties through the end of its run. Some spots in this area get 10" of rain-these are the source areas for the creeks that flow through Austin and this would cause severe flooding, so for our sake I hope that's off. Radar is really lighting up now along the various boundaries across this area. 

[NTXYankee]

Yea, the 12z GFS points to a couple more rounds of heavy rain for areas of Texas. Looks like the jackpot on this run moved from areas SW of Houston to areas to the NW of Houston. 

 

ETA: 12z Euro is back to hammering DFW overnight and has many areas with another 4-6" of rain

I don't know, honestly I don't see the Euro materializing around here, I think this heavy rain event might be over up this way by a day and a half early thanks to another outflow blowing through here.

[1900hurricane]

Almost all of the high-resolution guidance is showing >10" maxes somewhere in central Texas over the next 48 hours. Someone is going to get slammed.

[bubba hotep]

HRRR absolutely nails western Travis/Hays/Williamson/Bell Counties through the end of its run. Some spots in this area get 10" of rain-these are the source areas for the creeks that flow through Austin and this would cause severe flooding, so for our sake I hope that's off. Radar is really lighting up now along the various boundaries across this area. 

 

The HRRR has been a clown show so far today... just sad. Hopefully, it isn't finally getting it's act together because 10" in less that 15 hrs would be big trouble for those areas. Looking at the latest radar loops, it looks like the eastward propagation has ended and things are taking on more of a northward training pattern. 

[jm1220]

Very heavy rain training just to the west of here where terrain starts getting hilly, over toward Lake Travis. Looks like the terrain is aiding the lift, in addition to some of the boundaries setting up in a favorable place. Again, what's concerning is that this is the source area for several of Austin's creeks, and this is where the worst of the Memorial Day rains fell, causing a flash flood emergency to be declared for the city. So hopefully this starts to move soon. If not we could be in trouble. 

[Jebman]

I am absolutely elated over the forecasts. I am in Buda Texas until Tuesday morning at noon.

I hope we all get severely waterboarded for 2-3 days by severe rain rates.

 

That ground is saturated right now, all of the new rain is running off straight into Onion Creek. I am going to get to watch the water levels rise!!!!!! WOW! I got to see last October's rains too!

 

Thunder is starting! THIS MEANS THE CAP IS ERODING!!!

 

 

 

WOOOOOOOO-----HOOOOOOOO!!!!!!!

[cheese007]

Jesus why are you like this? People die in floods what is wrong with you?

[Jebman]

Jesus why are you like this? People die in floods what is wrong with you?

I sincerely hope that no one loses their life during or after this storm. Texans are some of the smartest people around. Everyone will be safe.

[bubba hotep]

[jm1220]

Loud thunder where I am but I'm just east of the torrential rain. Radar starting to estimate 2.5" under that band.

[bubba hotep]

Latest run of the HRRR gives someone 21" of rain in the next 15 hrs.... 

[jm1220]

Latest run of the HRRR gives someone 21" of rain in the next 15 hrs.... 

Yup. The rain now is a very early appetizer-the boundary overall spawning it is still pushing west with the strong SE flow here. The front will slowly sag south during the day and the real heavy rain looks to be tonight over a more widespread area, and the HRRR has focused on this area for several runs now. It's a bad location for places like Wimberley, Kyle, San Marcos and north/east from there. 

[bubba hotep]

MESOSCALE DISCUSSION 0406
NWS STORM PREDICTION CENTER NORMAN OK
0247 PM CDT SUN APR 17 2016

AREAS AFFECTED...SOUTH CENTRAL TEXAS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 171947Z - 172115Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...SCATTERED THUNDERSTORMS WILL CONCENTRATE ACROSS SOUTH
CENTRAL TEXAS OVER THE NEXT FEW HOURS. ISOLATED LARGE HAIL AND
PERHAPS A BRIEF TORNADO CAN BE EXPECTED.

DISCUSSION...NWWD-MOVING OUTFLOW WITH A BAND OF CONVECTION IS
PROPAGATING INTO THE I-35 CORRIDOR BETWEEN AUS AND SAT ATTM.
FARTHER NORTH...LARGER PRECIP SHIELD OVER CENTRAL TX IS GENERATING
SWD-MOVING WIND SHIFT THAT SHOULD INTERACT WITH THIS ACTIVITY AND
COULD ENHANCE CONVECTIVE POTENTIAL INVOF THE BALCONES ESCARPMENT.
LATEST MRMS DATA SUGGESTS MARGINALLY SEVERE HAIL HAS ACCOMPANIED
STORM THAT LIFTED ACROSS UVALDE INTO BANDERA COUNTY. SHEAR PROFILES
FAVOR DEEP ROTATING UPDRAFTS AND VARIOUS OUTFLOW
BOUNDARIES/INTERACTIONS COULD LOCALLY AID BRIEF TORNADO ACTIVITY.
WILL CONTINUE TO MONITOR THIS CONVECTION FOR POSSIBLE WW.

..DARROW/HART.. 04/17/2016

[bubba hotep]

The cell west of Bandera will be moving into an area possibly more conducive for a tornado as it moves towards Fredericksburg. 

[bubba hotep]

And another HRRR running spitting out 21" of rain