Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 231631
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1131 AM CDT SAT MAY 23 2015

                     VALID MAY 23 THROUGH MAY 28

...STORM SYSTEMS WILL CONTINUE TO BRING PARTS OF THE WGRFC AREA
LOCALLY HEAVY RAIN THROUGH EARLY TUESDAY...

                  ...METEOROLOGICAL DISCUSSION...
Little change in the overall weather pattern is expected into early
next week. The southwesterly upper air flow aloft will continue as
upper level storm systems continue to move out of the southwestern
U.S.  Deep moisture will persist over the region through the weekend
and early next week, with Precipitable Water (PW) values running 150
percent of normal and higher through the weekend.  With a favorable
pattern aloft and deep moisture in place, widespread showers and
thunderstorms are expected across much of the WGRFC area.  Most of
Texas and western Louisiana will see precipitation, with an additional
1 to 3 inches of rain expected.  Some locations will receive 5 to 7
inches (with locally higher amounts) in the more organized
thunderstorm complexes. Right now the most likely locations to receive
the heaviest amounts are centered on the DFW metroplex northward, and
over Houston, but this could change somewhat with time.

One upper level low pressure system was located west of the four
corners region this morning.  As this low pulls northeastward to
Wyoming by Monday morning it will help initiate widespread showers and
thunderstorms across the area.  Other sources of lift, including a
warm front which extends across north Texas, and residual outflow
boundaries from previous thunderstorms, could also help in the
development of thunderstorms across the region.  Where thunderstorm
activity becomes more organized, locally heavy rainfall can be
expected.  At this time, the most favorable timing for locally heavy
rainfall is later today and continuing into Sunday for most of Texas.
The heaviest rain should shift into east Texas and Louisiana on
Monday.

More showers and thunderstorms are forecast later Monday as the
next in a series of upper air disturbances moves across Texas.
However, this disturbance will move northeastward rather quickly and
should be out of the region by Tuesday morning. Thereafter, a weak
ridge of high pressure is forecast to move across Texas Tuesday and
Wednesday which may bring a 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 to southeast New Mexico and far
west Texas by Thursday morning.  This rain will move further east
into Texas during the Thursday/Friday time frame.

                    ...PRECIPITATION FORECAST...
For Today into Sunday morning, Mean Areal Precipitation (MAP) amounts
of 0.25 of an inch or more are forecast for much of Texas (except for
the far west and far east sections). The heaviest rain, with MAP
amounts of 3.00 inches, are forecast from just south of Gainesville
TX to the DFW metroplex. MAP amounts of 2.00 inches are forecast over
much of north Texas and parts of the Texas Hill Country.  Lighter
amounts of MAP are forecast for much of the remaining areas of the
WGRFC area of responsibility except for the southern two thirds of
New Mexico.

For Sunday into Monday morning, MAP amounts of 0.25 of an inch or
more are forecast for the eastern two thirds of Texas and most of
Louisiana. The heaviest rain, with MAP amounts of 3.00 inches, are
forecast over the Houston area.  MAP amounts of 1.00 inch are forecast
over most of the eastern half of Texas and western Louisiana.  Lighter
amounts of MAP are forecast for much of the remaining areas of the
WGRFC area of responsibility except for southern New Mexico and far
west Texas.

For Monday into Tuesday morning, MAP amounts of 0.25 of an inch or
more are forecast for the southeast two thirds of Texas and Louisiana.
The heaviest rain, with MAP amounts of 2.00 inches, are forecast over
much of east central Texas.  MAP amounts of 1.00 inch are forecast
over most of the southeastern half of Texas.  Lighter amounts of MAP
are forecast for much of the remaining areas of the WGRFC area of
responsibility except for southeastern New Mexico and far west Texas.

For Tuesday into Thursday morning, MAP amounts of 0.25 of an inch or
more are forecast for east Texas into Louisiana, as well as
over southeastern New Mexico and far west Texas. The heaviest rain,
with MAP amounts of 1.50 inches, are forecast over southwest
Louisiana near and north of Lake Charles. Lighter amounts of MAP are
forecast for much of the remaining areas of the WGRFC area of
responsibility except for the central and western parts of New
Mexico and the western parts of north Texas.

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 begun to rise due to
recent rainfall, and some lakes are full and are releasing water.  The
rainfall expected over the next five days over especially northern,
south central and southeast 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...
...Nueces Basin...
...Major Flooding...
A break in the rainfall allowed the Nueces to clear some of the water
down stream.  Asherton has fallen below major flood and continues to
recede. The water at Cotulla continues to rise well into major and is
approaching levels of the July 2002 storm, which looks to be the
benchmark for the rainfall that has already occurred over this area.
Downstream, Lake Corpus Christi has reduced their releases which will
alleviate some of the flooding downstream, at least temporarily.
Rainfall is expected to return to the area later today which could
alter the current status of the river.

...Trinity Basin...
...Major Flooding...
Ongoing widespread, 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.

...Guadalupe Basin...
...Moderate Flooding...
The flood wave on the Guadalupe River continues to move downstream.
The river has already crested at Victoria and is forecast to crest
later today downstream at Bloomington.  It should be noted that heavy
rainfall is forecast over the next couple days.  This could cause
additional flooding.

...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.  It should be noted
that heavy rainfall is forecast over the next couple days.  This could
cause additional flooding.

...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.

...Brazos Basin...
...Minor Flooding...
Higher than normal flow conditions are occurring on the lower Brazos
River system.   However, a couple of sites are still experiencing minor
flood conditions.  It should be noted that heavy rainfall is forecast
over the next couple days.  This could cause additional flooding.

...San Bernard Basin...
...Minor Flooding...
Higher than normal flows will continue across the lower San Bernard
river.  Additional rainfall over the next 2-3 days will produce
efficient runoff to cause higher rises; likely into minor flood levels
with moderate flooding possible.

...San Jacinto Basin...
...Higher Flow Non-Flood Forecasts...
Higher than normal flows will continue across most of the San Jacinto
River system through the weekend. Additional rainfall over the next
2-3 days will produce efficient runoff to cause higher rises; likely
into minor flood levels.

...Rio Grande Basin...
...Higher Flow Non-Flood Forecasts...
Reservoirs El Cuchillo and Marte Gomez along the lower Rio San Juan in
Mexico continue releasing, which are now bringing higher flows into the
mainstem Rio Grande near Rio Grande City (RGDT2).  These flows are
then diverted as regulated between US/Mexico at Anzalduas (MADT2).

...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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