Hydrometeorological Discussion
Issued by NWS West Gulf RFC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6
274
AGUS74 KFWR 211645
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1144 AM CDT THU MAY 21 2015

                     VALID MAY 21 THROUGH MAY 26

...NO END IN SIGHT TO THE STORM SYSTEMS WHICH COULD BRING PARTS OF THE
WGRFC AREA LOCALLY HEAVY RAIN THE NEXT FIVE DAYS...

                  ...METEOROLOGICAL DISCUSSION...
Southwesterly flow aloft is expected to continue the rest of the week
and through the weekend. Additional upper level disturbances are
expected to move through this flow and keep showers and thunderstorms,
with locally heavy rainfall, in the forecast for at least some parts
of Texas, extreme eastern New Mexico and western Louisiana for the
entire five day forecast period. In general, this additional rainfall
(with total amounts in excess of 8.00 inches, particularly in northern
and south central Texas) will likely cause additional moderate or
greater flooding across many of our river systems. The soils are moist
over much of Texas now, so any new rainfall will quickly run off. We
will continue to monitor the situation over the coming days and update
accordingly.

One upper air disturbance has been moving out of Mexico into Texas
the past 24 hours ahead of a new upper low that is moving close to
California. The disturbance produced showers and thunderstorms over
much of southwestern Texas into the Hill Country Wednesday evening,
while additional showers and thunderstorms formed behind a cold front
across north Texas.  Then early this morning a complex of
thunderstorms moved out of Mexico to the lower Rio Grande valley near
Laredo early Thursday morning.  Locally heavy rainfall occurred over
some locations, with around 4.00 inches of rain noted near Georgetown
TX and 3.75 inches southwest of Llano TX. Showers and thunderstorms
are shifting into east Texas this morning to go along with the
thunderstorms over deep south Texas.

The next upper air disturbance is forecast to move over eastern
New Mexico and southwest Texas this evening. More rain will develop
and will spread northeastward to cover eastern New Mexico and all of
west Texas tonight.  Then on Friday the upper disturbance will move
eastward and bring the chances for more showers and thunderstorms
further east to much of Texas. This rain will move into east Texas by
Saturday morning.

The main upper level low pressure system is forecast to move over
Colorado on Saturday. The next upper air disturbance ahead of this
low is forecast to produce showers and thunderstorms over west Texas
later on Saturday, which will move toward central and north Texas on
Sunday and over east Texas on Sunday night.  The rainfall should be
confined to east Texas and western Louisiana by Monday morning.
Locally heavy rainfall is possible over much of northern and
south central Texas this weekend into Monday.

Yet another upper air disturbance is forecast to move to the
Texas/New Mexico border region by Tuesday morning which may bring
more rain to parts of Texas.

                    ...PRECIPITATION FORECAST...
For Today into Friday morning, Mean Areal Precipitation (MAP) amounts
of 0.25 of an inch or more are forecast for most of Texas, most of
Louisiana, the northeastern two thirds of New Mexico and much of
Colorado. The heaviest rain, with MAP amounts of 2.00 inches, are
forecast from Laredo TX and around Falcon Reservoir to near Corpus
Christi.  Lighter amounts of MAP are forecast for much of the
remaining areas of the WGRFC area of responsibility except for
southwestern New Mexico.

For Friday into Saturday morning, MAP amounts of 0.25 of an inch or
more are forecast for the northwestern two thirds of Texas (except
for the far west) and eastern New Mexico.  The heaviest rain, with
MAP amounts of 1.00 inch, are forecast over west Texas to the
southwest of Lubbock.  Lighter amounts of MAP are forecast for much of
the remaining areas of the WGRFC area of responsibility except for
western New Mexico.

For Saturday into Sunday morning, MAP amounts of 0.25 of an inch or
more are forecast for central and west Texas (except for the far
west), western Louisiana and extreme northeastern New Mexico.  The
heaviest rain, with MAP amounts of 4.00 inches, are forecast just
west of Gainesville TX.  MAP amounts of 2.00 inches are forecast over
north central and extreme northwest Texas.  Lighter amounts of MAP are
forecast for much of the remaining areas of the WGRFC area of
responsibility except for the southwestern half of New Mexico.

For Sunday into Tuesday morning, MAP amounts of 0.25 of an inch or
more are forecast for most of Texas, Louisiana, extreme northern New
Mexico and southern Colorado. The heaviest rain, with MAP amounts of
3.00 inches, are forecast over southeast Oklahoma.  MAP amounts of
2.00 inches are forecast over north central into central and southeast
Texas.  Lighter amounts of MAP are forecast for much of the remaining
areas of the WGRFC area of responsibility except for southern 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 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 and
south central Texas will be heavy enough to produce significant
runoff, and minor runoff is expected over extreme eastern New Mexico
and the remainder of Texas.  Elsewhere over the WGRFC area no
significant runoff is anticipated.

                     ...HYDROLOGIC DISCUSSION...
...Nueces Basin...
...Major Flooding...
2 to 4 inches fell across the Asherton basin which will exacerbate the
major flooding conditions for the basin, however it is not expected to
crest at a higher level than previously forecast.  Should remain near
major flood for an extended period before falling off near the end of
the forecast period.  This water will move downstream but will
attenuate as it spreads causing a reduction in flow as it arrives
downstream at Cottula.  Cottula will rise a tad higher into major
flood, but not a significant change.  It will take some time for the
water to reach Tilden, but Tilden should remain around the moderate
flood stage for some time.  Three Rivers has dropped below major and
will continue to fall over the next few days. Lake Corpus Christi has
raised its releases to 12,100 which pushes Mathis, Bluntzer, and
Calallen even further into their current conditions.

...Guadalupe Basin...
...Moderate Flooding...
A flood wave continues to move downstream that crested on both Sandies
Creek and Gonzales, which should push Cuero further up into minor flood
stage.  This should move down to Victoria later this weekend in
moderate flood, and continue to keep Bloomington in moderate throughout
the forecast period.

...San Jacinto Basin...
...Moderate Flooding...
The West Fork San Jacinto near Porter (PTET2) is continues in moderate
flood level and continues to fall.

...Trinity Basin...
...Moderate 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.

...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
cresting 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.

...Sabine Basin...
...Moderate Flooding...
Minor flooding continues in the Sabine River Basin with moderate
flooding forecast near Bon Weir as Toledo Bend Reservoir continues to
pass large inflows.

...Lavaca-Navidad Basin...
...Minor Flooding...
Minor flooding continues in the Lavaca River Basin.

...Colorado Basin...
...Minor Flooding...
Locally heavy rains caused Llano River near Junction (JNCT2) to crest
above minor flood levels and has now fallen below bankfull this
morning.  The Llano River near Mason (MLRT2) has not responded yet to
the heavy rains but is expected rise slightly above action stage today.
 Sandy Creek near Kingsland (KNLT2) has risen slightly above action
stage and should fall below action sometime this morning.  The Colorado
River downstream at Wharton (WHAT2) and Bay City (BAYT2) are expected

...Brazos Basin...
...Minor Flooding...
Several sites along the lower Brazos remain in flood.  Middle Yegua
Creek and the Navasota River are also in minor flood due to recent
local rainfall.

...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

$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.