April 2016 Recap: Regional Flood/Severe Weather

[Ounce]

To this layman, on the Water Vapor loop, does it look like the northern and southern jets rub against each other before splitting around San Antonio?

[tireman4]

This will be a long day and night. Please be careful all. Stay alert. This is an ever changing situation. Stay tuned here or your local media/weather outlets. Have your phones charged and your weather radio batteries fresh ( if you still have one of them..LOL) The mets here (Srain, Wxman 57, Jeff, David, Brooks and Andrew) will alert and advise. Also the many fine folks that contribute to this forum will help as well. We could not do it without all of you.

[jeff]

Several meso models really blast the area overnight with a W to E training line. Tremendous rainfall rates of 2-4 inches per hr on top of wet grounds equals a dangerous flash flood setup.

I stress....Turn Around Don't Drown. We must make a strong effort to prevent flood fatalities in vehicles.

[srainhoutx]

Several meso models really blast the area overnight with a W to E training line. Tremendous rainfall rates of 2-4 inches per hr on top of wet grounds equals a dangerous flash flood setup.

I stress....Turn Around Don't Drown. We must make a strong effort to prevent flood fatalities in vehicles.

Jeff, I know you and the NWS folks are monitoring the HRRR/NAM solutions rather carefully. I also cannot stress enough that folks need to plan on being off the roads tonight into tomorrow morning. I have seen some solutions particularly from the HRRR that suggest isolated totals possibly nearing the 7 to 10 inch amount. While know one knows where this East to West boundary may become established, we really need to monitor the radar trends and stay very weather aware. Let those that may not be so weather wise know that there are weather worry possibilities for our Region.

[mcheer23]

Jeff, do you have a link to that?

[Ounce]

Two cells crossing the border at Del Rio. One headed NE, the other headed SSE.

[DoctorMu]

ADDITIONAL SUPPORT FOR WARM CLOUD/RAINFALL EFFICIENT IS
DRIVEN BY HIGH DENSITY OF SMOKE METEORS FROM YUCATAN/TABASCO
AGRICULTURAL FIRES AND WILL ACT AS CONDENSATION NUCLEI FOR MORE
NUMEROUS RAINDROP PRODUCTION... ALL CONSIDERED RATES OF 2-3"/HR
ARE PROBABLE.[/quote][/quote]
Just a little Tabasco sauce is all we want.[/quote]

Lol.. All we need is a little more heat.. No thank you![/quote]

Where there's smoke, there's fire.

[srainhoutx]

Jeff, do you have a link to that?

This should help with your question...

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

.DISCUSSION...
...FLASH FLOOD WATCH EXPANDED IN AREA TO INCLUDE LIBERTY/CHAMBERS
GALVESTON/BRAZORIA COUNTIES. SEVERE THREAT SLIGHT TO ENHANCED
ACROSS THE REGION THIS AFTERNOON AND TONIGHT...

INGREDIENTS ALL IN PLACE NOW ACROSS THE REGION. PW 1.25-1.5 AND
CLIMBING. TEMPERATURES HAVE SOARED TO 85-88 DEGREES ACROSS THE
NORTH AND WINDS HAVE BEGUN TO INCREASE AND GET GUSTY. SETX IS
GOING TO BE UNDER THE GUN TONIGHT FOR SEVERE AND VERY HEAVY
RAINFALL.

SEVERE POTENTIAL SHOULD START OUT AS TORNADO/HAIL THREAT IN THE
WEST AND THEN SHIFT EASTWARD THROUGHOUT THE EVENING. AS WE GET
INTO THE EVENING THE THREAT SHOULD ALSO INCLUDE DAMAGING WINDS
ACROSS THE REGION...WET GROUND WILL ALLOW FOR TREE FALL AT LOWER
WIND SPEEDS THAN NORMAL.

FLOODING THREAT FOR MANY RUNS OF THE HRRR/NAM POINT TO AN EAST
WEST BOUNDARY ACROSS SETX...LOCATION MAY BE WELL NORTH OF THE
HOUSTON METRO AREA OR FURTHER SOUTH INTO THE METRO AREA. THIS
COULD BE A VERY DANGEROUS SITUATION IF THIS SETS UP ALONG THE
SPRING CREEK TO I-10 CORRIDOR. RAINFALL RATES OF 2-4 INCHES WILL
BE EASY TO ACHIEVE IN THIS PRECIPITATION EFFICIENT ENVIRONMENT
GIVEN THE VERY STRONG LL INFLOW AND LL SATURATION. EVENTUALLY
THIS STORM COMPLEX SLIDES EAST AND SHOULD BE MOVING OUT OF THE
AREA AROUND NOON SATURDAY OR PERHAPS EARLIER IF THE COLD POOL CAN
GET MORE DOMINANT BUT THROUGH 3 AM THIS SEEMS UNLIKELY THAT IT
COULD SURGE EAST OUT OF THE REGION. THE COLD FRONT PUSHES DOWN
ACROSS THE AREA LATE SATURDAY AND BRINGS IN DRYING AT LEAST OVER
THE NW 2/3RDS OF THE AREA.

BEYOND SATURDAY THE STATIONARY BOUNDARY REMAINS IN PLAY ACROSS
THE SOUTHERN PORTIONS OF THE AREA OR NEARSHORE WATERS AND THEN AS
NEXT TROUGH DROPS IN OVER THE WESTERN U.S. THE FRONT ACTIVATES
AGAIN SUNDAY AND PROBABLY MORE LIKELY MONDAY AND TUESDAY AS NEXT
UPPER LOW EJECTS OUT OF THE MEAN UPPER TROUGH. THE 'GOOD' NEWS IS
THAT STRONG LL INFLOW IS NOT NEARLY AS STRONG WITH THE SUNDAY-
TUESDAY TIMEFRAME SO STORMS WILL PROBABLY MORE SCATTERED AND NOT
AS FOCUSED.

PERSONS ACROSS SETX LATE THIS AFTERNOON AND OVERNIGHT SHOULD BE
PREPARED FOR A VERY ROUGH NIGHT OF WEATHER.

[wxman57]

The HRRR model seems overly-enthusiastic about rainfall across Houston. It has widespread 14-18" across the southern half of Harris County tonight. Euro and GFS are in the 2-4" range. I'm not seeing anything to suggest we'll see enough rain to make Brays and/or Buffalo Bayou overflow their banks this time. Street flooding may be the main issue. Watch out for those underpasses...

[Andrew]

Large tornado likely on the ground in Oklahoma

[Andrew]

Texas A&M Special sounding this afternoon

[jasons2k]

Well this is interesting. One of our respected pro-mets is playing it up with an abundance of caution, and another saying just a street flooding issue.

You just never know with these systems. With the tax day storm, we got a lot rain as forecasted, but how the event was modeled vs. what actually happened were two different things. The dumping we got was almost a day earlier than expected.

Moral of the story, whether you are a novice or a pro-met, nobody knows exactly how this will unfold. Just keep a close watch out, pay attention to warnings, and turn around - don't drown!

[Andrew]

Well this is interesting. One of our respected pro-mets is playing it up with an abundance of caution, and another saying just a street flooding issue.

You just never know with these systems. With the tax day storm, we got a lot rain as forecasted, but how the event was modeled vs. what actually happened were two different things. The dumping we got was almost a day earlier than expected.

Moral of the story, whether you are a novice or a pro-met, nobody knows exactly how this will unfold. Just keep a close watch out, pay attention to warnings, and turn around - don't drown!

Idk if Jeff is exactly playing it up and just more siding with caution due to the already oversaturated grounds and full reservoirs/ rivers. But that is just my two cents. You are correct though in saying how difficult it is to forecast these systems.

[mcheer23]

I saw the HRRR model has Harris, Fort Bend, Brazoria counties getting HAMMERED.

Although I saw another model barley has rain for the area...

[Ounce]

The clouds associated with that stationary cell south of Del Rio stretch to San Antonio, now.

[unome]

nothing like ground truth - pay close attn to radar - those storms in north/central tx blew up incredibly quick - I'll be sleeping really light tonight...

and it may be cliche, but prepare for the worst & hope for the best !

[unome]

http://www.wpc.ncep.noaa.gov/metwatch/m ... 51&yr=2016



MESOSCALE PRECIPITATION DISCUSSION 0151
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
620 PM EDT FRI APR 29 2016

AREAS AFFECTED...SE TEXAS

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

VALID 292220Z - 300130Z

SUMMARY...HIGHLY EFFICIENT CONVECTIVE EVENT WITH REPEAT
DEVELOPMENT AND TRAINING IS POSSIBLE. STILL MUCH UNCERTAINTY AS
TO WHEN AND WHERE OR EVEN IF A FOCUSED EVENT WOULD SETUP.

DISCUSSION...DEPICTING A WORST CASE SCENARIO ON A LOCAL
SCALE...RAPID REFRESH HI-RES CAMS SUCH AS THE HRRR AND RAP
CONTINUE TO SUGGEST THE EVOLUTION OF A LINE OF CONVECTION ACROSS
SE TX. A SURGE OF HIGH MOISTURE IS ANALYZED IN MULTIPLE REMOTE
SENSING PRODUCTS WITH BLENDED TPWS VALUES IN THE 2-2.25"
RANGE...SUPPORTED BY 50 KT LLJ. ADDITIONALLY ALOFT...SUBTLE
SHORTWAVE NEAR KLRD WOULD PROVIDE MILD DPVA AND WITH INCREASED
DIFFLUENCE ALOFT BETWEEN A SPLIT JET SETUP...THE POTENTIAL FOR
REDEVELOPMENT/BACKBUILDING TO OCCUR. AS THE POSSIBLE COMPLEX
DEVELOPS A WEAK COLD POOL AND SHIFTING NE OF SHORTWAVE ENERGY
WOULD LEAVE AN EFFECTIVE OUTFLOW BOUNDARY ORIENTED FAVORABLY TO
THE CONTINUED STRONG ONSHORE MOISTURE TRANSPORT FOR CONTINUED
STRONG CONVERGENCE AND FLUX TO MAINTAIN RAINFALL EFFICIENCIES IN
THE 3-4"/HR RANGE.
ALONG WITH THE RECENT HRRR/RAP RUNS THE 18Z GEM-REGIONAL IS ALSO
SUPPORTIVE OF THIS SETUP WITH TOTALS THROUGH 04-05Z IN THE 4-5"
RANGE.

HOWEVER...EARLIER THIS AFTERNOON A SURGE OF DRY AIR IN THE RETURN
FLOW FROM THE NORTH AND CENTRAL GULF HAS KEPT CINH RELATIVELY HIGH
IN THE 25-75 J/KG RANGE. THIS IS HELPING TO KEEP CONVECTIVE
DEVELOPMENT SEEN IN SRSO VIS/IR FROM GOES-14 FURTHER WEST; FROM
MATAGORDA BAY NORTH TOWARD THE MATURING MCS ACROSS N TX...IN LINE
WITH SOME OF THE DRIER CAMS OVER SE TX SUCH AS THE WRF-ARW AND THE
HI-RES MEANS: HREF AND SSEO.

OBSERVATIONALLY...THE HIGHLY DEFINED CU FIELDS OVER THE WESTERN
GULF ARE WASHING OUT WITH SURGES IN THE MARINE LAYER SEEN MOVING
NORTH BETWEEN 94-96W THROUGH BREAKS IN THE SUBTROPICAL JET CIRRUS
SUGGESTING THE BULGE OF HIGHER TPWS SEEN IN EARLY MORNING POLAR
PASSES IS MAKING ITS WAY NORTH IN LINE WITH THE RAP ANALYSIS
FIELDS. THIS BREEDS INCREASING CONFIDENCE TOWARD THE RAPID
REFRESHING CAMS TREND WITH THE POTENTIAL FOR LOCALLY HEAVY
RAINFALL LATER THIS EVENING BUT WITH A LARGE AMOUNT OF REMAINING
UNCERTAINTY AS TO WHERE THE EVENT WILL FOCUS. WILL UPDATE MPD BY
0130Z.

GALLINA/BURKE

ATTN...WFO...EWX...FWD...HGX...LCH...SHV...

ATTN...RFC...WGRFC...

[tireman4]

From the HGX AFD...read the last sentence.....

000
FXUS64 KHGX 292041
AFDHGX

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

.DISCUSSION...
...FLASH FLOOD WATCH EXPANDED IN AREA TO INCLUDE LIBERTY/CHAMBERS
GALVESTON/BRAZORIA COUNTIES. SEVERE THREAT SLIGHT TO ENHANCED
ACROSS THE REGION THIS AFTERNOON AND TONIGHT...

INGREDIENTS ALL IN PLACE NOW ACROSS THE REGION. PW 1.25-1.5 AND
CLIMBING. TEMPERATURES HAVE SOARED TO 85-88 DEGREES ACROSS THE
NORTH AND WINDS HAVE BEGUN TO INCREASE AND GET GUSTY. SETX IS
GOING TO BE UNDER THE GUN TONIGHT FOR SEVERE AND VERY HEAVY
RAINFALL.

SEVERE POTENTIAL SHOULD START OUT AS TORNADO/HAIL THREAT IN THE
WEST AND THEN SHIFT EASTWARD THROUGHOUT THE EVENING. AS WE GET
INTO THE EVENING THE THREAT SHOULD ALSO INCLUDE DAMAGING WINDS
ACROSS THE REGION...WET GROUND WILL ALLOW FOR TREE FALL AT LOWER
WIND SPEEDS THAN NORMAL.

FLOODING THREAT FOR MANY RUNS OF THE HRRR/NAM POINT TO AN EAST
WEST BOUNDARY ACROSS SETX...LOCATION MAY BE WELL NORTH OF THE
HOUSTON METRO AREA OR FURTHER SOUTH INTO THE METRO AREA. THIS
COULD BE A VERY DANGEROUS SITUATION IF THIS SETS UP ALONG THE
SPRING CREEK TO I-10 CORRIDOR. RAINFALL RATES OF 2-4 INCHES WILL
BE EASY TO ACHIEVE IN THIS PRECIPITATION EFFICIENT ENVIRONMENT
GIVEN THE VERY STRONG LL INFLOW AND LL SATURATION. EVENTUALLY
THIS STORM COMPLEX SLIDES EAST AND SHOULD BE MOVING OUT OF THE
AREA AROUND NOON SATURDAY OR PERHAPS EARLIER IF THE COLD POOL CAN
GET MORE DOMINANT BUT THROUGH 3 AM THIS SEEMS UNLIKELY THAT IT
COULD SURGE EAST OUT OF THE REGION. THE COLD FRONT PUSHES DOWN
ACROSS THE AREA LATE SATURDAY AND BRINGS IN DRYING AT LEAST OVER
THE NW 2/3RDS OF THE AREA.

BEYOND SATURDAY THE STATIONARY BOUNDARY REMAINS IN PLAY ACROSS
THE SOUTHERN PORTIONS OF THE AREA OR NEARSHORE WATERS AND THEN AS
NEXT TROUGH DROPS IN OVER THE WESTERN U.S. THE FRONT ACTIVATES
AGAIN SUNDAY AND PROBABLY MORE LIKELY MONDAY AND TUESDAY AS NEXT
UPPER LOW EJECTS OUT OF THE MEAN UPPER TROUGH. THE `GOOD` NEWS IS
THAT STRONG LL INFLOW IS NOT NEARLY AS STRONG WITH THE SUNDAY-
TUESDAY TIMEFRAME SO STORMS WILL PROBABLY MORE SCATTERED AND NOT
AS FOCUSED.

PERSONS ACROSS SETX LATE THIS AFTERNOON AND OVERNIGHT SHOULD BE
PREPARED FOR A VERY ROUGH NIGHT OF WEATHER.

[unome]

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

[tireman4]

And as I post this, the winds have really picked up in Humble. This will be a long night. Please all be weather wary.