Hydrometeorological Discussion
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AGUS74 KFWR 261648
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1148 AM CDT TUE MAY 26 2015

                     VALID MAY 26 THROUGH MAY 31

...A STORM SYSTEM WILL BRING PARTS OF THE WGRFC AREA LOCALLY HEAVY
RAIN AGAIN AT THE END OF THE WEEK...

                  ...METEOROLOGICAL DISCUSSION...
A strong upper level disturbance moved from southwest to northeast
across Texas the past 24 hours. Showers and thunderstorms formed
over southwest Texas Monday morning which spread over the remainder
of the state from Monday afternoon into Tuesday morning.  The
heaviest showers and thunderstorms fell over central and southeastern
Texas.  Rainfall amounts of 10 to 12 inches fell near Houston,
particularly around Richmond TX. This rain created moderate to major
flooding.  And over central Texas around 8 inches fell just east of
Austin which created new flooding as well.  This upper disturbance
moved northeastward rather quickly and is now out of the region.
Therefore the majority of the rain moved east, and the lingering
rainfall which was over southeast Texas has dissipated.

One additional minor upper air disturbance is forecast to cross north
Texas this afternoon and evening. This trough, combined with the
dryline, will produce scattered showers and thunderstorms over western
and northern Texas this afternoon and tonight. Heavy rainfall is not
expected.  Then a weak ridge of high pressure is forecast to move
across Texas Wednesday which should bring a temporary break to the
widespread rainfall.

By Thursday morning a new upper air disturbance is forecast to
approach our region from the west.  This is forecast to produce a new
area of showers and thunderstorms over eastern New Mexico and far
west Texas by Thursday morning.  This rain will then move further
northeast and cover the northwest half of Texas during the day
Thursday into Friday.  Some locally heavy rainfall is forecast over
northwest Texas.  The first disturbance is forecast to move northeast
of our region by Friday night. Thereafter, minor upper air
disturbances are forecast to cross north Texas Saturday into Sunday.
Additional rainfall is forecast, especially over the western parts
of north Texas, and the WGRFC will continue to monitor this storm and
update as needed.

                    ...PRECIPITATION FORECAST...
For Today into Wednesday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 of an inch are forecast for portions of northern,
eastern and southern Texas into much of Louisiana. The heaviest
rain, with MAP amounts of 0.50 inch, are forecast from southwest
Louisiana eastward across southern Louisiana.  Lighter amounts of MAP
are forecast for the eastern two thirds of Texas, extreme northern New
Mexico and Colorado.

For Wednesday into Thursday morning, MAP amounts of 0.25 of an inch
are forecast for the northeast third of Texas and northern Louisiana.
Lighter amounts of MAP are forecast for much of the remaining areas of
the WGRFC area of responsibility except for western New Mexico and
over deep south Texas.

For Thursday into Friday morning, MAP amounts of 0.25 of an inch or
more are forecast for eastern New Mexico and the northwest half of
Texas.  The heaviest rain, with MAP amounts of 1.00 inch, are forecast
over west Texas northwest of Abilene.  Lighter amounts of MAP are
forecast for much of the remaining areas of the WGRFC area of
responsibility except for western New Mexico and over deep south
Texas.

For Friday into Sunday morning, MAP amounts of 0.25 of an inch or
more are forecast for northeastern New Mexico and the northwestern
two thirds of Texas and northern Louisiana.  The heaviest rain, with
MAP amounts of 1.00 inch, are forecast over northwest and north
central Texas from north of San Angelo to Wichita Falls and the DFW
metroplex to Sherman and Denison TX.  Lighter amounts of MAP are
forecast for much of the remaining areas of the WGRFC area of
responsibility except for extreme southwestern New Mexico.

Drought conditions continue to improve across most of the WGRFC area.
Recent precipitation events have brought drought relief to many parts
of Texas.  In Texas, only about 15% of the state is experiencing
moderate or worse drought, and extreme to exceptional drought
conditions are no longer being observed.  In New Mexico, a little over
a third of the state is experiencing moderate or worse drought (37%),
and they also are free from extreme or exceptional drought conditions.
Many of the lakes in Texas have levels which have risen due to
recent rainfall, and some lakes are full and are releasing water.  The
rainfall expected over the next five days over especially the
northern half of Texas will be heavy enough to produce significant
runoff, and minor runoff is expected over the remainder of Texas.
Elsewhere over the WGRFC area no significant runoff is anticipated.

                     ...HYDROLOGIC DISCUSSION...
...Guadalupe Basin...
...Major Flooding...
Another round of very heavy, localized rainfall (4 to 6 inches) over
the Luling area produced efficient runoff along the Plum, Peach, and
Sandies Creek, as well as the San Marcos River.  This caused
significant flood levels into major within these watersheds and another
quick rise within major flood at Luling on the San Marcos (LLGT2).
Further downstream on the mainstem Guadalupe at Gonzales (GNLT2), this
flood wave will follow on the heels of the Wimberley flood wave that
passed yesterday, bringing another rise with major flood level likely.
Downstream at Cuero (CUET2), the high flows from Peach and Sandies
Creeks join which will add to duration and possibly the crest height.
Further along the mainstem

Both these flood waves have caused major damage along it`s path of the
Blanco and San Marcos River mainstem, and now moving along the
Guadalupe mainstem.  These combined waves are expected to cause major
flooding as it moves downstream along the mainstem through Cuero
(CUET2), Victoria (VICT2), and Bloomington (DUPT2) to the coastal
outlet.  This event comes in the wake of an earlier flood wave still
moving  further downstream; now cresting through Bloomington (DUPT2).

...Nueces Basin...
...Major Flooding...
Inflows into Choke Canyon Reservoir are on the increase. The Frio River
near Derby (DBYT2) is nearing a crest within moderate flood stage. This
will cause a rise downstream at Tilden (TIDT2) in to minor flood late
in the week. San Miguel Creek (TNLT2) is also on the increase, but is
expected to remain below flood stage. Choke Canyon is well below the
top of the conservation pool at this time and is increasing only
slowly. On the Nueces River, upstream points at Asherton (ASRT2) and
Cotulla (COTT2) have crested and will remain near steady to slowly
falling. Water is now moving downstream to Tilden (TILT2), which will
be rising into major flood over the next few days. Three Rivers (THET2)
will be rising into moderate flood late in the week. Inflows into Lake
Corpus Christi will once again be on the increase this week due to
these rises. Releases are down to 3900 cfs, which will cause further
decreases at Bluntzer (CBVT2) and Calallen (CAAT2). Depending on how
much inflow comes into the reservoir, renewed increases in release are
possible at some point later in the week.

...San Jacinto Basin...
...Major Flooding...
Excessive rainfall amounts ranging from 3 to 10 inches were observed in
Harris County overnight. This caused widespread moderate to major
flooding on the Bayous near the city of Houston. Most of these
locations have crested and are falling. Greens Bayou at Ley Road
(GBLT2) is still experiencing a rise and will crest around 2 feet above
major flood stage today. Further north, the West Fork San Jacinto River
near Humble (HMMT2) is increasing within moderate flood levels. The
West Fork San Jacinto near Porter (PTET2) will approach major flood
stage today. Other tributaries of the San Jacinto have reached action
stage or minor flood stage. As a result, Lake Houston is on the rise.
With levels currently approaching 44 feet, outflow to the San Jacinto
River near Sheldon (SHLT2) is on the increase. This location is
expected to approach minor flood stage on Wednesday.

...Trinity Basin...
...Major Flooding...
Heavy rainfall across the entire Trinity River drainage has caused
widespread bankfull, minor, and moderate flood flow conditions.  Flood
control reservoirs continue to store flood waters minimizing
downstream flood conditions.

...Colorado Basin...
...Major Flooding...
Heavy rain has fallen over the last 24 hours mainly over the middle and
lower Colorado River Basin.  River stages upstream of Austin have
already crested and fallen below criteria.  Downstream, the rivers
continue to rise along the mainstem Colorado and its tributaries.  Some
of these locations are forecast to crest at major flood levels.  For
the upper Colorado River basin, Colorado City is the only location
forecast to rise into higher than normal flow levels.

...Brazos Basin...
...Major Flooding...
Heavy, localized rainfall (4 to 6 inches) across the Little River
watersheds and mainstem Brazos around Hempstead and Richmond; more
widespread lesser rainfall across most of the lower Brazos river
system.  This has caused significant flooding into major levels along
the Little River system into the mainstem Brazos, as well as, the
Navasota River system through Lake Limestone into the mainstem Brazos
further downstream near Hempstead.  Minor and moderate flooding
occurring or expected throughout the lower mainstem.

...Lavaca-Navidad Basin...
...Moderate Flooding...
Heavy rain has fallen over the last 24 hours over the upper and middle
Lavaca and Navidad rivers.  Several locations are forecast to crest at
either minor or moderate flood levels.

...Neches Basin...
...Moderate Flooding...
The Neches River system remains in elevated flow levels with several
locations currently in flood.  The Neches River near Alto (ATOT2) is
at moderate levels.  Multiple other sites will remain in their minor
to action stage levels with the recent rainfalls adding to the already
elevated flows.  Many mainstem forecast points are expected to remain
in minor flood levels for at least the next week.  Lake Steinhagen is
expected to increase releases as inflows increase from upstream routed
flows and forecast rainfall runoff.

...Sabine Basin...
...Moderate Flooding...
Moderate flooding continues on the lower Sabine River Basin through Bon
Wier (BWRT2) and Deweyville (DWYT2) as Toledo Bend Reservoir continues
to pass large inflows.  Minor flooding continues on upstream
tributaries such as the Cowleech Fork (GNVT2), South Fork (QLAT2) and
Lake Fork (QTMT2).

...San Antonio Basin...
...Moderate Flooding...
Cibolo Creek near Falls City (FCTT2) appears to have crested just below
major flood levels early this morning.  The San Antonio River at Goliad
(GLIT2) is on the rise and expected to crest in moderate flood levels
later this week.

...San Bernard Basin...
...Moderate Flooding...
Heavy rainfall skirted across the San Bernard River basin overnight
causing quick rises on the river.  At Boling (BOLT2) the river has
already risen 13 feet in the past 12 hours, into moderate flood levels.
 Downstream at Sweeny (SWYT2) the river is expected to rise to moderate
levels over the next couple of days.

...Rio Grande Basin...
...Higher Flow Non-Flood Forecasts...
Releases out of Marte Gomez Reservoir in Mexico are driving a rise on
the Rio Grande near San Benito and Ramirez (SBNT2). At this time the
river is expected to rise an additional 4 feet.

...Remainder of WGRFC Basins...
Currently, most rivers are have ongoing flooding conditions and
remain very sensitive to further rainfall.  Soil conditions remain
very saturated and any further rainfall will only exacerbate the
ongoing flooding.

              ...SUPPLEMENTARY GRAPHICAL INFORMATION...
The following URLs (all lower case) provide additional graphical
information on current and forecast hydrologic conditions, past and
future precipitation, and drought and climate forecasts.  This
information is provided by a variety of National Weather Service,
NOAA, and private sector entities.

For specific information on river conditions, refer to the AHPS
pages from the local NWS offices at:
http://water.weather.gov/ahps/

The Flood Potential Outlook can be viewed on our webpage at:
http://www.srh.noaa.gov/wgrfc/?n=wgrfcfop

The West Gulf River Forecast Center is now on Facebook:
http://www.facebook.com/US.NationalWeatherService.WGRFC.gov

National Precipitation Analysis:
http://water.weather.gov/precip/

The forecast rainfall amounts (QPF) can be viewed on our webpage at:
http://www.srh.noaa.gov/wgrfc/?n=wgrfcqpfpage

The US Drought Assessment:
http://www.cpc.ncep.noaa.gov/products/Drought

The latest on Reservoir Information for Texas:
http://www.waterdatafortexas.org

STORY

$$




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