April 2016 Recap: Regional Flood/Severe Weather

[wxman57]

Not to distract from task at hand, but in the long-range forecast, anyone seeing this NEXT big upper low diving down, farther south than the current one-- per the EURO, for late next week?

Could be problematic for SE Texas if it doesn't lift out/accelerate to the NE but moves slowly eastward. Early indications favor the former.

[srainhoutx]

Afternoon updated quantitative precipitation forecast for the next 3,days from the Weather Prediction Center.

[srainhoutx]

Next shortwave rounding the base of the upper trough can be seen over the Sierra Madre Mountains in Mexico near Monterrey heading generally ENE along the upper flow. Will need to monitor this feature particularly during the early morning hours for any storms that fire and begin to line up to our SW and W. Moisture levels have really increased further this afternoon as the low level jet has increased off the Gulf with the seabreeze.

[Katdaddy]

Flash Flood Watch continues for SE TX through this evening. MCS moving across NTX this morning is approaching N portions of SE TX with mesoscale models indicating a weakening trend while additional development development occurs along the outflow boundary later today. Models shows most areas with less than 2" totals with a few isolated higher totals of 3-4" possible. A cold front tomorrow will bring another round of showers and thunderstorms with two day average totals from 1-3" across SE TX. Much lower rainfall totals are very good news after the previous deluge but could still have some additional impacts on basins, creeks, bayous, and rivers. The SPC also has a marginal risk of severe thunderstorms across SE TX. Friday afternoon and Saturday still looking like nice days before moisture begins to return from the GOM.

[srainhoutx]

Morning briefing from Jeff:

As expected line of thunderstorms approaching from the NW this morning with additional heavy rainfall expected across much of the region with this line.

Air mass has recovered nicely from Monday with good low level moisture advection in place and dewpoints back into the 60’s and 70’s supporting plenty of energy for this line of storms to continue SE into the region. Seeing a general decreasing trend with the radar coverage along with line, but the portion east of Austin remains fairly strong. Well defined cold pool should keep the complex moving on through the region.

Upstream radar estimates showing 1-2 inches of rainfall with this line and this seems reasonable as it moves across the area. Based on radar trends probably favoring the lower end of this range, but given the super sensitivity of the area to additional rainfall at this point will need to watch trends closely.

Should see onset by 800am NW Harris and off the coast by 1000am

Watershed Flooding:

Cypress Creek (entire length, creek has crested and falling, but remains well overbanks)

Little Cypress Creek: creek is back within banks

Willow Creek: creek is back within banks

Spring Creek: creek is overbanks from Kuykendahl downstream to San Jacinto River with significant flooding along the Montgomery County side of the creek

South Mayde Creek: Creek remains overbanks on the upper and lower ends

Cypress Creek Overflow: Overflow of Cypress Creek into Addicks continues across western Harris County, but is lessening. Still large areas are still inundated from the Waller County line to east of Katy Hockley Rd

Addicks: pool is now 100.6 and rising. Forecast to reach 102.3. HWY 6 is under 2-3 ft of water and forecast pool may put water into streets in the Bear Creek Village subdivision. HWY 6 will remain closed for many days

Barker: pool is now 93.2 ft and rising. Forecast to reach 96.7 ft which is flooding streets in Fort Bend County. Strerts will likely be flooded in Harris County also.

[unome]

SPC Day 7 = 15%

DAY 7. THE MODELS
SUGGEST A DRYLINE ORGANIZES ACROSS THE SRN PLAINS DURING THE DAY ON
TUESDAY WITH THUNDERSTORMS DEVELOPING ALONG AND EAST OF THE DRYLINE
LATE TUESDAY AFTERNOON. THE ECMWF SOLUTION ALSO SHOWS THE EXIT
REGION OF A MID-LEVEL JET OVERSPREADING THE SRN PLAINS ON TUESDAY.
THE MODELS ARE IN GENERAL AGREEMENT AND HAVE SHOWN ENOUGH RUN TO RUN
CONSISTENCY TO ADD A 15 PERCENT CONTOUR FOR PARTS OF CNTRL AND NORTH
TX...OK...SRN KS...NW AR AND FAR SW MO FOR TUESDAY AND TUESDAY
NIGHT. A SEVERE WEATHER EVENT WITH TORNADOES...LARGE HAIL AND WIND
DAMAGE WILL BE POSSIBLE.

[nuby3]

what time zone does jeff live in?

[tireman4]

Jeff lives in the Houston area. Central Time Zone.

[tireman4]

Not to distract from task at hand, but in the long-range forecast, anyone seeing this NEXT big upper low diving down, farther south than the current one-- per the EURO, for late next week?

Could be problematic for SE Texas if it doesn't lift out/accelerate to the NE but moves slowly eastward. Early indications favor the former.

Even more reason to stay vigilant.

[davidiowx]

That line approaching us is moving so FAST

[srainhoutx]

That line approaching us is moving so FAST

Yes it is. the stronger cells are capable of dropping about 1.25 inches per hour, but generally 1/2 inch amounts are expected. Hopefully this line will keep chugging along and get off the Coast in short order.

[djmike]

It is moving fast. My only concern is I have seen a few runs slowing this line or even stalling before moving off the coast. Hopefully it will make it offshore! At this point, no more rain is needed.

[nuby3]

It is moving fast. My only concern is I have seen a few runs slowing this line or even stalling before moving off the coast. Hopefully it will make it offshore! At this point, no more rain is needed.

I've been wondering if all of the water on the ground would help it strengthen at all. interesting to watch, looks to be centering the activity over waller somewhat. hopefully it does chug on out of here. makes me nervous for a lot of my friends and family watching that cell approach

[srainhoutx]

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
846 AM CDT WED APR 20 2016

COLORADO TX-WASHINGTON TX-SAN JACINTO TX-WALLER TX-GRIMES TX-
MONTGOMERY TX-POLK TX-HARRIS TX-AUSTIN TX-FORT BEND TX-
846 AM CDT WED APR 20 2016

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS EXTENDED THE

* FLOOD WARNING FOR...
NORTHERN COLORADO COUNTY IN SOUTHEASTERN TEXAS...
SOUTHEASTERN WASHINGTON COUNTY IN SOUTHEASTERN TEXAS...
SOUTHERN SAN JACINTO COUNTY IN SOUTHEASTERN TEXAS...
WALLER COUNTY IN SOUTHEASTERN TEXAS...
SOUTHEASTERN GRIMES COUNTY IN SOUTHEASTERN TEXAS...
SOUTHERN MONTGOMERY COUNTY IN SOUTHEASTERN TEXAS...
SOUTHWESTERN POLK COUNTY IN SOUTHEASTERN TEXAS...
WESTERN HARRIS COUNTY IN SOUTHEASTERN TEXAS...
AUSTIN COUNTY IN SOUTHEASTERN TEXAS...
NORTHERN FORT BEND COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 615 PM CDT WEDNESDAY

* AT 842 AM CDT...HEAVY RAINFALL FROM PREVIOUS DAYS HAS LED TO
WIDESPREAD AREAL FLOODING AS WELL AS FLOODING ALONG THE
STREAMS...BAYOUS...AND RIVERS. WATER LEVELS AT SOME SITES WERE
ALREADY RECEDING. AT OTHER SITES...THE PEAK OF THE FLOODING IS
EXPECTED TODAY. ADDITIONAL RAINFALL FROM RAIN AND THUNDERSTORMS IS
POSSIBLE TODAY.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
SUGAR LAND...NORTHWESTERN MISSOURI CITY...SOUTHERN CONROE...EASTERN
ROSENBERG...STAFFORD...BELLAIRE...BRENHAM...WEST UNIVERSITY PLACE...
KATY...RICHMOND...TOMBALL...JERSEY VILLAGE...SEALY...HEMPSTEAD...PRAIRIE
VIEW...BROOKSHIRE...HUNTERS CREEK VILLAGE...BELLVILLE...COLUMBUS AND
BUNKER HILL VILLAGE.

ADDITIONAL RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE POSSIBLE IN THE
WARNED AREA.

[Texashawk]

If they say the 'trend is your friend', then I don't like the trend of this line in general. Seems to be slowing down and pulling in a lot of moisture ahead of it.

[djmike]

Ha. Just as I posted 30 min ago. System beginning to stall. Will begin pulling in multiple amounts of moisture as it now begins tapping into the gulf.

[djmike]

Heavy cell now over NW Harris county. EXACTLY where we don't need it. Growing a little concerned as this line has slowed substantially in the last 20min.

[srainhoutx]

So far about .60 of inch with the line as it moved through in NW Harris County. Still getting some light with embedded moderate rain showers behind the line, but it is moving SE about 20-25 MPH.

[srainhoutx]

Regarding the sensible weather forecast for the next 24 to 36 hours. Some of the 12Z meso models do indicate another round of showers and thunderstorms organizing tonight over NW, N Central Texas and pushing SE tomorrow morning. Still not seeing anything that suggests more than an inch or two of rainfall with the overnight storms developing tonight. Then we appear to dry out over the weekend before attention turns to the next storm system dropping SE out of the Gulf of Alaska early to mid next week.

[srainhoutx]

MESOSCALE PRECIPITATION DISCUSSION 0132
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1111 AM EDT WED APR 20 2016

AREAS AFFECTED...WESTERN GULF COAST/LOWER MS VALLEY

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

VALID 201515Z - 202115Z

SUMMARY...AN APPROACHING OUTFLOW BOUNDARY, INCREASING MOISTURE,
AND INCREASING INSTABILITY SHOULD ALLOW FOR INCREASING
THUNDERSTORMS COVERAGE. CONVECTIVE MERGERS AND SHORT PERIODS OF
CELL TRAINING ARE POSSIBLE THIS AFTERNOON, WHICH COULD LEAD TO
FLASH FLOODING.

DISCUSSION...THE REMAINS OF A SQUALL LINE ARE LIMPING THROUGH
WESTERN AR, NORTHWEST LA, AND EASTERN TX AT THE PRESENT TIME.
THIS OUTFLOW BOUNDARY IS LURING A DEW POINT GRADIENT/WEAK WARM
FRONT INTO SOUTHWEST LA. PRECIPITABLE WATER VALUES OF ~1.5" LIE
WITHIN THE WARM SECTOR ALONG WITH MLCAPES OF 1000+ J/KG. A PAIR
OF SHORTWAVES, ONE CONVECTIVE AND ONE WITHIN THE MAIN BELT OF THE
WESTERLIES, ARE APPROACHING THE REGION FROM THE WEST, ACTING TO
ENHANCE DIVERGENCE ALOFT. INFLOW AT 850 HPA REMAINS NEAR 25 KTS.

THE CAM GUIDANCE SHOWS A SIGNAL FOR LOCAL 2-4" AMOUNTS WITHIN AN
AREA THAT SHOWS FAIRLY PERSISTENT 850 HPA CONVERGENCE. WITH THE
LOW CLOUD DECK ACROSS PORTIONS OF LA TRYING TO MIX OUT/CONVECT PER
RECENT SATELLITE IMAGERY, INSTABILITY SHOULD BUILD NORTHEAST
TOWARDS WESTERN MS AND SOUTHEAST AR WITH TIME, WHICH IS ADVERTISED
BY THE RAP GUIDANCE. LOW-LEVEL INFLOW COULD INCREASE SLIGHTLY
THIS AFTERNOON AS THE PAIR OF SHORTWAVES APPROACH. FAIRLY
UNIDIRECTIONAL SOUTHWEST FLOW IMPLIES CELL TRAINING POSSIBILITIES,
WHILE DIFFERING VECTORS FOR THUNDERSTORM MOTION (NORTHEAST AT ~20
KTS FOR PULSE ACTIVITY AND EAST-SOUTHEAST AT ~10-15 KTS FOR
ORGANIZED CLUSTERS) HINT AT THE POSSIBILITY OF CELL MERGERS WITH
TIME, PARTICULARLY NEAR THE END OF THIS MPD'S WINDOW. HOURLY RAIN
RATES UP TO 1.75" ARE POSSIBLE WHERE CELLS MERGE AND/OR TRAIN.
WITH FLASH FLOOD GUIDANCE VALUES DEPRESSED FROM RECENT RAINFALL
WHICH HAS SATURATED AREA SOILS TO SOME DEGREE, FLASH FLOODING IS
CONSIDERED POSSIBLE.

ROTH

ATTN...WFO...HGX...JAN...LCH...LIX...LZK...MEG...SHV...