Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 021615
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1115 AM CDT MON MAY 2 2016

                      VALID MAY 2 THROUGH MAY 7

...AN ACTIVE WEATHER PATTERN WILL CONTINUE ANOTHER DAY OR TWO BEFORE
A DRYING TREND BEGINS BY THE MIDDLE OF THE WEEK...

                  ...METEOROLOGICAL DISCUSSION...
Another storm system is affecting the WGRFC area this morning, but
its grip on the region will diminish by tonight. This storm is
currently bringing another round of showers and thunderstorms, and
earlier brought some periods of snowfall to the higher elevations
of New Mexico and Colorado.  ahead of this storm, showers and
thunderstorms developed Sunday along the upper Texas Gulf coast into
southern Louisiana along a cold front. These thunderstorms have
now moved offshore over the Gulf of Mexico.  Showers and
thunderstorms also formed from west Texas into northern and central
Texas the past 24 hours. The heaviest rain the past 24 hours occurred
over southwestern Louisiana where the Lake Charles LA area received
an additional 5.00 to 9.50 inches. In Texas, Woodville received 5.00
inches.  This latest low pressure system moved from Arizona eastward
to Oklahoma the past 24 hours. This low will continue to weaken as it
shifts quickly eastward today, and an upper level trough will move
across Texas.  As this occurs there will be some residual showers and
a few thunderstorms over the southeastern half of Texas and western
Louisiana today into late tonight before ending.

A final upper air disturbance is forecast to move southeastward
across Oklahoma Tuesday and across Texas Tuesday night and Wednesday
morning. Aside from some light showers over the western parts of
north Texas during the time of maximum heating Tuesday, little or no
precipitation will occur from this disturbance.

Drier conditions will finally return to the region Wednesday through
early Saturday morning as a ridge of high pressure develops over the
Rocky Mountains and moves eastward over Texas.

By Saturday morning a new low pressure system will be moving from
southern California to southwestern Utah.  Ahead of this low,
moisture is forecast to begin flowing northward.  This may result in
some precipitation over parts of far southwest Texas, New Mexico and
Colorado by Saturday morning.

                    ...PRECIPITATION FORECAST...
For Today into Tuesday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 of an inch or more are forecast over roughly the
southeast half of Texas and most of Louisiana.  The heaviest rain,
with MAP amounts of 1.50 inches, are forecast for the lower Sabine
River eastward into southern Louisiana.  MAP amounts of less than
0.25 of an inch are forecast over the southeast two thirds of Texas
and Louisiana, the northwest half of New Mexico and a good part of
Colorado.

For Tuesday into Wednesday morning, no significant MAP amounts are
forecast for the WGRFC area.  MAP amounts of less than 0.25 of an
inch are forecast over the western parts of north Texas westward into
the Texas panhandle, over a good part of New Mexico and southern
Colorado.

For Wednesday into Thursday morning, no significant MAP amounts are
forecast for the WGRFC area.

For Thursday into Saturday morning, no significant MAP amounts are
forecast for the WGRFC area.  MAP amounts of less than 0.25 of an
inch are forecast over the northeast third of New Mexico and most of
Colorado, and far southwestern Texas.

Soil moisture rebounded this past week as an active weather pattern
produced abundant rain.  Soils are now very moist across a good part
of the state, especially the eastern portions. Texas is now
categorized as being 13% abnormally dry, with 2% in the moderate
drought category. These dry areas are confined to the Texas panhandle
and the far western portions of the state, with the remainder of the
state free of drought.  Over New Mexico, almost the entire state
remains in the abnormally dry category, and 44% is in moderate
drought. The rainfall which is forecast over the next 5 days may
produce significant additional runoff into the rivers over extreme
southeastern Texas and western Louisiana, as those areas have
saturated soils.  Elsewhere, only minor amounts of runoff are
expected.

                     ...HYDROLOGIC DISCUSSION...
...San Jacinto Basin...
...Major Flooding...
Additional rains have caused the East Fork San Jacinto to experience
a sharp rise near New Caney (NCET2) and is expected to crest
slightly above major flood levels for a brief period.  Other sites
are in slow recession at this time.

...Trinity Basin...
...Major Flooding...
Heavy rain fell across portions of the Trinity River basin over the
past 3 days, which will cause moderate to major flooding for several
areas along the river.

Both Cedar Creek Reservoir and Lake Livingston are currently passing
inflow from upstream runoff.  These releases are generating moderate
flood levels on the mainstem Trinity River at Trinidad (TDDT2) and Long
Lake (LOLT2).  Downstream, the Trinity River at Liberty (LBYT2) is
forecast to rise into major flood levels by the
middle of the week.

For the upper Trinity, water supply reservoirs are passing inflows to
maintain their conservation pools.  Flood control reservoirs are also
evacuating their flood pools.  This is keeping the mainstem of the
Trinity and its tributaries well above normal.

...Sabine Basin...
...Major Flooding...
Water continues to make its way through the system from the upstream on
down.  The routed water will push Gladewater into major flood.
Multiple other sites will remain elevated and continue to rise into
moderate flood impacting local roadways and agriculture.  Toledo Bend
has already raised their releases today and it is still raining over
the lake so more releases may be required.  This will create minor
flooding currently downstream of the lake.

...Neches Basin...
...Moderate Flooding...
Recent rainfall in the upper half of the Neches River Basin has  pushed
numerous forecast points into minor and moderate flood stage.  Lakes
remain full with flood storage being slowly released as it can be from
Sam Rayburn Reservoir.

...Brazos Basin...
...Minor Flooding...
Higher than normal flows continue on the lower Brazos River due to
recent heavy rainfall,. Navasota River at Easterly (EAST2) and near
Normangee (NGET2) are the only sites in this basin that are forecast
to go into minor flood from the recent rainfall.

...San Bernard Basin...
...Higher Flow Non-Flood Forecasts...
Heavy rain has slowed the recession within action stage for Sweeny
(SWYT2) but should be below action stage over the next couple of days.

...Remainder of WGRFC Basins...
Soils remain wet over most of the WGRFC area, but a little break
from rainfall is expected after the last of this rain event leaves
the region. Next shot at significant rain will be next Monday.

For today`s remnant rain, location and amounts of rainfall will be
critical in determining  river response, but the heaviest rainfall is
expected to remain over southeastern portions of Texas.

              ...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/reservoirs/statewide

STORY

$$





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