Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 291627
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1126 AM CDT FRI APR 29 2016

                    VALID APRIL 29 THROUGH MAY 4

...AN ACTIVE WEATHER PATTERN WILL CONTINUE INTO EARLY NEXT WEEK
BEFORE A DRYING TREND BEGINS BY THE MIDDLE OF THE WEEK...

                  ...METEOROLOGICAL DISCUSSION...
A series of weather producers will continue to affect the WGRFC area
through the weekend into the first part of next week. This will
result in a couple rounds of showers and thunderstorms, as well as
some periods of snowfall in the higher elevations of New Mexico and
Colorado.

The first system is located near the Four Corners region this
morning. This low is bringing precipitation to New Mexico and
Colorado which will eventually spread eastward.  Further east, a
minor upper air disturbance ahead of this low is bringing showers and
thunderstorms across extreme north Texas and Oklahoma.  The low near
the Four Corners will move across southern Colorado today, and as
this occurs the dryline will become active across central Texas.
Numerous showers and thunderstorms will develop across west Texas
this morning and will increase this afternoon over east Texas,
including the DFW metroplex. The upper level low will lift northeast
into Kansas by Saturday morning and most of the showers and
thunderstorms will move east of our region.

On Saturday, a cold front and dryline are forecast to move into
southeast Texas and will stall.  This will result in additional
periods of scattered showers and thunderstorms with intermittent
heavy rainfall from roughly Houston and Lake Charles into southern
and central Louisiana.  This system may hang around through Sunday
which would bring additional rainfall to the upper Texas Gulf coast
region.  Meanwhile, a new low pressure system will be digging over
Arizona on Sunday morning.  This low will spread additional
precipitation over New Mexico and Colorado, with showers and
thunderstorms spreading into west Texas Sunday afternoon into
Monday.

The main system will begin to weaken and will shift east by Monday,
with some residual rainfall expected for the southeastern half of
Texas and western Louisiana Monday into Tuesday morning.  Drier
conditions will finally return to the region later Tuesday into
Wednesday as a ridge of high pressure develops over the Rocky
Mountains.

                    ...PRECIPITATION FORECAST...
For Today into Saturday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 of an inch or more are forecast over central and
east Texas into western Louisiana, portions of southern Colorado,
and extreme northeast New Mexico.  The heaviest rain, with MAP
amounts of 3.00 inches, are forecast for extreme east Texas and
along the LA-TX-AR borders.  MAP amounts of less than 0.25 of an
inch are forecast over the northeast two thirds of Texas, the
northern half of New Mexico and Colorado.

For Saturday into Sunday morning, MAP amounts of 0.25 of an inch or
more are forecast over the southeast third of Texas into Louisiana,
much of southern Colorado, and northern New Mexico. The heaviest
rain, with MAP amounts of 2.00 inches, are forecast for extreme
southeast Texas into southwest Louisiana.  MAP amounts of less than
0.25 of an inch are forecast over the southeast half of Texas, the
northwestern half of New Mexico and most of Colorado.

For Sunday into Monday morning, MAP amounts of 0.25 of an inch or
more are forecast along and near the middle and upper Texas Gulf
coast, as well as over the western quarter of Texas into much of
southern Colorado and the northeastern half of New Mexico. The
heaviest rain, with MAP amounts of 1.50 inches, are forecast for
southwestern Texas northwest of Del Rio.  MAP amounts of less than
0.25 of an inch are forecast over most of Texas and Louisiana, the
northeastern three quarters of New Mexico and Colorado.

For Monday into Wednesday morning, MAP amounts of 0.25 of an inch or
more are forecast over the southeast half of Texas, Louisiana, as
well as over a few spots over southern Colorado and northeastern New
Mexico. The heaviest rain, with MAP amounts of 2.00 inches, are
forecast for the upper Texas Gulf coastline.  MAP amounts of 1.00
inch are forecast over southeast Texas into southern Louisiana.  MAP
amounts of less than 0.25 of an inch are forecast over most of the
remaining portions of the WGRFC area.

Soil moisture has rebounded this week as an active weather pattern
continues to produce abundant rain. Soils have moistened across a
good part of the state. 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 is remains in the
abnormally dry category, and 44% is in moderate drought. The rainfall
which is forecast over the next 5 days will produce additional runoff
into the rivers over the eastern half of Texas and western Louisiana.
Significant runoff should be expected over those areas with saturated
soils.  Elsewhere, only minor amounts of runoff are expected.

                     ...HYDROLOGIC DISCUSSION...
...Trinity Basin...
...Moderate Flooding...
A regular pattern of rainfall across the Trinity River system continues
to generate higher flows and slow recessions throughout the basin.
Several locations are still above minor and moderate flood levels
(TDDT2), (LOLT2). The uppermost portion of the river, above Fort Worth,
is still flowing well above normal with all the water supply lakes
passing inflows to maintain
their conservation pools.   That water is keeping the mainstem of the
West Fork of the Trinity well above normal all the way to Dallas, which
controls the release plans for most of the flood control projects
within the DFW metroplex.  Until the water from upstream decreases, the
DFW lakes are limited on flood pool evacuations, but are releasing as
much as possible given the next rain heavy rain event expected to begin
this afternoon overnight into early Saturday morning.  With the
forecast rainfall, minor flood conditions are possible across the upper
Trinity down to Rosser and moderate flooding possible downstream along
the mainstem through Liberty.

...Neches Basin...
...Minor Flooding...
The latest round of forecasts for the Neches include a 24-hour QPF
forcing. The most significant QPF from the 24-hour period influence
falls on the middle to upper section of the basin, where up to 2 inches
of QPF may materialize during the 4/30 6z period. This precipitation
will produce minor rises on several of the rivers, which have not
recovered from the previous weeks flooding. The precipitation is not
expected to push the Neches system out of the minor category level
through the weekend.

...Brazos Basin...
...Minor Flooding...
Higher than normal flows continue on the lower Brazos River due to
last weeks heavy rainfall. Another round of rainfall is expected
today and tonight in the middle and lower Brazos River basin, which
will likely cause renewed flooding on tributaries in the area.

...Sabine Basin...
...Minor Flooding...
Lakes are still trying to evacuate their flood pools as more rain is
set to arrive today into tonight.  Rainfall will be highly localized
for the heavier amounts but widespread could see 1 to 3 inches of
rainfall.  The rainfall is not expecting to generate significant
flooding but an isolated area could see a higher amount with these
convective systems.  Multiple sites in the upper basin will reach
minor flood which Toledo Bend will pass downstream keeping flows
elevated down through Deweyville.

...San Jacinto Basin...
...Higher Flow Non-Flood Forecasts...
Based on 24 hr qpf, 3 points within the San Jacinto basin are expected
to climb into action stage.

...San Bernard Basin...
...Higher Flow Non-Flood Forecasts...
Based on 24 hr qpf, EBBT2 is expected to climb back into action stage
by tomorrow, and the recession within action stage for SWYT2 will be
slowed compared to previous forecasts.

...Guadalupe Basin...
All points along the Guadalupe River have fallen below criteria.

...Remainder of WGRFC Basins...
Unsettled weather is in the forecast for the next 5 days and beyond.
Location and amounts of rainfall will be critical in determining
flood potential. Heaviest rainfall is expected Friday and into next
week.

              ...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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