April 2016 Recap: Regional Flood/Severe Weather

[Texaspirate11]

CIMSS TPW loop shows the dry air the SPC spoke of

http://tropic.ssec.wisc.edu/real-time/m ... /main.html

http://tropic.ssec.wisc.edu/real-time/m ... t72hrs.gif

That's a bit of good news.....

[Katdaddy]

The current situation is handled well by everyone on the forum. "Turn around. Don't drown!!!" I so agree with Jeff. "Turn around. Don't drown!!!" Spread the word to friends, family, and co-workers. Needless loss of life that could be easily avoided. A dynamic visible satellite image this evening.

[mcheer23]

Hmm waiting for the cap to break..

[srainhoutx]

Updated Weather Prediction Center Excessive Rainfall Outlook. Still monitoring the boundary roughly from Matagorda Bay on NE toward the Lufkin area for development as some of that drier air mixes out. NWS Houston/Galveston continues to suggest this will be a wait and see situation. Highlighted the discussion important to SE Texas...

04292016 2244Z Excessive Rainfall 94ewbg.gif

...22Z UPDATE...

VERY LITTLE CHANGE TO THE SPATIAL LAYOUT OF THE DAY 1 RISK AREAS.
UPDATED TEXT TO REFRESH THE CURRENTLY OBSERVED STATE OF CONVECTION
AND TO DESCRIBE LATEST THINKING. A HIGH RISK OF EXCESSIVE RAINFALL
REMAINS IN PLACE OVER THE ARKLATEX...PARTS OF ADJACENT
OKLAHOMA...AND EXTENDING INTO CENTRAL ARKANSAS. THE MOST INTENSE
PERIOD OF RAINFALL HAD ENDED OVER THIS AREA...BUT WIDESPREAD
MODERATE TO OCCASIONALLY HEAVY RAIN WILL CONTINUE THROUGH THIS
EVENING...COMPOUNDING THE ONGOING PROBLEMS CAUSED BY EARLIER
INTENSE RAINFALL. ADDITIONAL AVERAGE RAINFALL OF 1 TO 2 INCHES IS
FORECAST THROUGHOUT THE HIGH RISK AREA OVERNIGHT...WITH POTENTIAL
FOR EMBEDDED AMOUNTS EXCEEDING 2.5 INCHES.

A MODERATE RISK EXTENDS SOUTHWARD...COVERING MUCH OF EASTERN TEXAS
AND AND NORTHWEST LOUISIANA. IN THE NEAR TERM...THROUGH
03-05Z...IT APPEARS THE GREATEST CONCENTRATION OF HEAVY RAIN WILL
OCCUR IN NORTHEAST TX AND ADJACENT PARTS OF THE ARKLATEX...ON THE
SOUTHERN PERIPHERY OF THE HIGH RISK AREA...WHERE THE MID LEVEL
LIFT AND LOW LEVEL INFLOW RESPONSE AHEAD OF A MIGRATING UPPER
TROUGH WILL OVERLAP WITH AN INSTABILITY GRADIENT / ENHANCED WARM
ADVECTION NORTH OF A WELL ESTABLISHED OUTFLOW BOUNDARY.

GRADUALLY THE FOCUS IS EXPECTED SHIFT SOUTHWARD...INTO THE PINEY
WOODS OVERNIGHT. THE SYNOPTIC SIGNAL PEAKS FROM LONGVIEW TO LUFKIN
TO NEAR HOUSTON...IN TERMS OF CONFLUENT LOW LEVEL FLOW...STRONG
MOISTURE TRANSPORT...AND PERSISTENT DEEP LAYER ASCENT. HENCE...THE
MODERATE RISK AREA IS FAIRLY WIDE FROM THE PINEY WOODS INTO
NORTHWEST LOUISIANA...BUT THEN NARROWS TOWARD HOUSTON...WITH A QPF
GRADIENT TOWARD LESSER VALUES BEING FORECAST WEST OF HOUSTON.
GIVEN ANTECEDENT CONDITIONS...THE FORECAST FOR SOUTHEAST TEXAS IS
PARTICULARLY SENSITIVE...AND ALSO PARTICULARLY DIFFICULT...AS
OUTLINED IN RECENT MESOSCALE PRECIPITATION DISCUSSION NUMBER 0151.
THERE IS SOME SIGNAL FROM THE NSSL WRF AND GEM REGIONAL...AND MOST
NOTABLY THE HRRR...FOR VERY HEAVY RAIN RATES TO OCCUR IN A FOCUSED
WAY...AT LEAST LOCALLY...ACROSS SOUTHEAST TEXAS. THE TIMING AND
PLACEMENT IN THE HRRR HAS BEEN MIGRATING...HOWEVER...FROM RUN TO
RUN. WITH SYNOPTIC LIFT MAXIMIZED FARTHER NORTH...ANY ANCHORED AND
WELL DEVELOPED EVENT OVER SOUTHEAST TEXAS MAY INITIATE FROM THE
STORM SCALE UP...WHICH AFFORDS LITTLE CONFIDENCE IN EXACTLY WHICH
AREA IS MORE LIKELY TO SEE HEAVY RAIN. IF CONVECTION DOES BECOME
ESTABLISHED...THOUGH...AND ANCHORED...THE RAINFALL EFFICIENCY WILL
BE AT THE HIGH END OF THE SPECTRUM...GIVEN STRONG CAPE AND
INCREASINGLY ANOMALOUS PRECIPITABLE WATER EXCEEDING 2.0 INCHES AND
2.0 STANDARD DEVIATIONS ABOVE THE MEAN.

THE WPC QPF FORECAST LEANS MORE TOWARD THE NSSL WRF AND
WRF-ARW...ALTHOUGH A SMALL SCALE INTENSE RAIN EVENT IN THE STYLE
OF THE HRRR COULD OCCUR SOMEWHERE OVER SOUTHEAST TEXAS.
BURKE

[unome]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
637 PM CDT FRI APR 29 2016

.AVIATION...
ELOW TO MODERATE CONFIDNCE FORECAST. MOISTURE AXIS FROM MATAGORDA
BAY TO KCLL TO MADISON COUNTY SHOULD SLOWLY MOVE EASTWARD THROUGH
THE NIGHT. SHOWERS AND THUNDERSTORMS WERE DEVELOPING WITHIN THE
MOIST AXIS. MODEL SOLUTIONS DIFFERED...HOWEVER THERE WAS ENOUGH
CONSENSUS BETWEEN THE GFS/NAM12/RAP13 TO TRY AND TIME THE EVENT
TONIGHT AND SATURDAY. TERMINALS WERE BASED ON THE NAM12 AND RAP13
AND THE PREVIOUS PACKAGE.

[unome]

MESOSCALE PRECIPITATION DISCUSSION 0152
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
802 PM EDT FRI APR 29 2016

AREAS AFFECTED...SE OKLAHOMA...SW ARKANSAS...NE TEXAS...EXT NW
LOUSIANA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 300002Z - 300502Z

SUMMARY...LARGE MCS WILL CONTINUE TO SUPPORT HEAVY RAINFALL
PRODUCTION ALONG EMBEDDED BOUNDARIES AND LIKELY OVER AREAS
AFFECTED THIS MORNING...LEADING TO LIKELY FLASH FLOODING ACROSS NE
TX/SW AR.

DISCUSSION...IR/VIS LOOP INDICATES LARGE MATURE MCS ACROSS THE
ARKLATX REGION BETWEEN THE BROAD SPLIT FLOW BETWEEN THE APEX OF
THE SUBTROPICAL JET SOUTH OF 30N AND THE 110-120 KT 3H POLAR JET
CYCLONICALLY CURVED ACRSS THE TX PANHANDLE. THE MCS IS ALSO AT
THE NOSE OF DEEP INCREASINGLY CONFLUENT LOW LEVEL FLOW WITH A
BROAD SWATH OF 1.5" TPWS FROM DFW-SAT AXIS TO HOU-SHV AS FAR N/NE
AS SW AR...WITH MAX VALUES OVER 2" OVER NE TX. MUDDLED SFC
BOUNDARIES DUE TO EARLY MORNING MCS AND OLD FRONTAL BOUNDARIES
CONTINUE TO FOCUS EMBEDDED DEEP CONVECTION WITH OVERSHOOTING TOPS
BREAKING OUT OVER THE TOP OF CIRRUS PARTICUALARLY AT THE BEST
CONVERGENCE AT THE SW EDGE IN NE TX NEAR KTYR/GGG. MUCAPE
INSTABILTY WITHIN THIS DEEP MOISTURE AXIS/CONFLUENT FLOW ARE
FORECAST TO BE MAINTAIN EVEN RISE TO 1500-2000 J/KG NE TX INTO SW
TO CENTRAL AR NEARLY COINSIDENT WITH AREA OF LOWEST FFG VALUES
FROM THIS MORNINGS ROUND OF FLASH FLOODING AND AS SUCH WILL KEEP
UPDAFTS AND RAINFALL EFFICIENCY HIGH WITH RATES UP TO 2"/HR WITH
DEEPEST CONVECTION...AND GIVEN ORIENTATION TO THE FLOW...SOME CELL
TRAINING IS POSSIBLE. HI-RES CAMS SUCH AS THE 18Z ESRL
HRRR...OPERATIONAL HRRR RUNS AND ARW CONTINUE TO PRODUCE A SWATH
OF 2-5" ACROSS NE TX/SW AR...MAKING FLASH FLOODING LIKELY.

GALLINA

...PLEASE SEE http://WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FWD...HGX...LZK...MEG...OUN...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...

[davidiowx]

Surely the flood risk is here tonight given how we don't need anymore rain... but it's certainly looking like a big time event up in the NE Texas, SE Arkansas and NW Louisiana area..

[srainhoutx]

Will need to watch recent development just West of San Antonio. That area appears to be attempting to back build to the S and the dryline is only creeping E further to the W of the Hill Country. Could see a MCS organizing across the Hill Country Lakes Region as well. Beginning to think the guidance was way too fast moving rain and storms into our area.

[Ptarmigan]

I notice many of these heavy rain happens at night, like the most recent one. I would not be surprised if we see heavy rain later tonight.

[jasons2k]

So far the cap is holding, but watching the area towards Port Aransas/Rockport/Victoria now.

[davidiowx]

Steve, just based off of your current atmospheric observations.. Do you see a squall line developing and moving through at a steady pace? Albeit maybe slowly, but moving... Or do you think it could move across our area and potentially slow down or maybe stall, and continue to back build as it sits here?

The HRRR is very concerning but also the outlier. If memory serves me right, I think the HRRR did pretty good (short term) on the Tax day storms. Or am I mistaking? It's been a long week.. :-/

I know it is almost impossible to say, especially since the event is unfolding and model watching is not a good reference point now, but I'm just curious as to what you think; given the winds picking up, the super humid/heavy air and the lift that appears to be available as the night progresses.

[srainhoutx]

The Tax Day flood event was well modeled by the Global guidance a good 5 days ahead of that event David. This has been a very tricky event to attempt to forecast accurately particularly when trying to be sensitive to all those suffering from the April 17-18 Regional Flood. Still believe the best we can do is watch the radar trends overnight into tomorrow. Still have little confidence with any computer model accurately sniffing out Mesoscale features beyond an hour or two ahead of where we see actual storm development.

[unome]

MESOSCALE DISCUSSION 0506
NWS STORM PREDICTION CENTER NORMAN OK
0807 PM CDT FRI APR 29 2016

AREAS AFFECTED...MUCH OF CENTRAL TEXAS

CONCERNING...TORNADO WATCH 124...

VALID 300107Z - 300230Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 124 CONTINUES.

SUMMARY...SEVERE STORM DEVELOPMENT IS EXPECTED TO PERSIST ACROSS
MUCH OF CENTRAL TEXAS THROUGH MUCH OF THE EVENING...ROUGHLY CENTERED
ON THE I-35 CORRIDOR BETWEEN SAN ANTONIO AND DALLAS/FORT WORTH. A
NEW SEVERE WEATHER WATCH MAY BE NEEDED SOUTH OF TORNADO WATCH 124
WITHIN THE NEXT HOUR OR SO.

DISCUSSION...DIFLUENT UPPER FLOW BETWEEN THE BASE OF NEGATIVELY
TILTED UPPER TROUGHING NOW SHIFTING INTO THE CENTRAL AND SOUTHERN
PLAINS...AND A ZONAL SUBTROPICAL JET AXIS ACROSS THE LOWER RIO
GRANDE VALLEY...LIKELY IS ENHANCING CONVECTIVE DEVELOPMENT AHEAD OF
THE DRYLINE TO THE SOUTH SOUTHWEST OF THE DALLAS/FORT WORTH
METROPLEX. SUSTAINED DISCRETE STORMS HAVE BEEN OCCURRING TO THE
WEST/AND NORTHWEST OF THE WACO/TEMPLE AREAS...AND STORMS ARE
INITIATING AS INHIBITION WEAKENS SOUTHWARD INTO THE HILL COUNTRY AND
ADJACENT PORTIONS OF THE EDWARDS PLATEAU.

IN THE PRESENCE OF LARGE CAPE ON THE ORDER OF 1500-3000+
J/KG...FURTHER CONVECTIVE DEVELOPMENT/INTENSIFICATION AND
ORGANIZATION APPEARS POSSIBLE THROUGH THE 02-04Z TIME...ACROSS AND
NORTH OF THE SAN ANTONIO AREA INTO AREAS SOUTH OF THE METROPLEX.
SOUTHERLY LOW-LEVEL FLOW APPEARS TO HAVE STRENGTHENED ACROSS THIS
REGION...ON THE WESTERN EDGE OF A 40-50 KT 850 MB JET. AN UPSCALE
GROWING MESOSCALE CONVECTIVE SYSTEM MAY NOT BE OUT OF THE QUESTION.
IF THIS OCCURS...DAMAGING WIND POTENTIAL PROBABLY WILL INCREASE. IN
THE MEANTIME...A TORNADO OR TWO IS POSSIBLE...IN ADDITION TO THE
CONTINUING RISK FOR SEVERE HAIL.

..KERR.. 04/30/2016

...PLEASE SEE http://WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...HGX...FWD...EWX...SJT...

[jasons2k]

Yessir. Patience, folks. LLJ is just starting to crank. Just keep a close watch out west on the radar and satellite.

[wxman57]

Steve, just based off of your current atmospheric observations.. Do you see a squall line developing and moving through at a steady pace? Albeit maybe slowly, but moving... Or do you think it could move across our area and potentially slow down or maybe stall, and continue to back build as it sits here?

The HRRR is very concerning but also the outlier. If memory serves me right, I think the HRRR did pretty good (short term) on the Tax day storms. Or am I mistaking? It's been a long week.. :-/

I know it is almost impossible to say, especially since the event is unfolding and model watching is not a good reference point now, but I'm just curious as to what you think; given the winds picking up, the super humid/heavy air and the lift that appears to be available as the night progresses.

I've found the HRRR often way too high with rainfall totals.

[davidiowx]

Thanks srain and wxman, it's always good to hear yalls input on the models as well as your personal opinions. Let's pray for the best! But prepare for the worst. It's better safe than sorry when events like this threaten our area. I love the interaction and knowledge on this forum. It's the best around.

[unome]

SEL7

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 127
NWS STORM PREDICTION CENTER NORMAN OK
820 PM CDT FRI APR 29 2016

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
CENTRAL TEXAS

* EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 820 PM
UNTIL 300 AM CDT.

* PRIMARY THREATS INCLUDE...
ISOLATED VERY LARGE HAIL EVENTS TO 2 INCHES IN DIAMETER POSSIBLE
ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

SUMMARY...ISOLATED TO SCATTERED INTENSE THUNDERSTORMS WILL CONTINUE
TO DEVELOP ACROSS PARTS OF CENTRAL TX THIS EVENING AND TONIGHT. THE
STRONGER CELLS WILL POSE A RISK OF LARGE HAIL AND DAMAGING WINDS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES EAST AND WEST OF A LINE FROM 70 MILES SOUTHWEST OF
HONDO TEXAS TO 50 MILES NORTH OF AUSTIN TEXAS. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 124...WW 125...WW 126...

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 24025.


...HART

[houstonia]

So, am I correct in thinking it looks like this system is heading toward our area at a slower progress than forecast? Since there's still a lot going on in central Texas?

[unome]

http://www.spc.noaa.gov/products/exper/enhtstm/

[srainhoutx]

So, am I correct in thinking it looks like this system is heading toward our area at a slower progress than forecast? Since there's still a lot going on in central Texas?

That appears to be correct houstonia.