Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 041546
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1045 AM CDT MON MAY 4 2015

                      VALID MAY 4 THROUGH MAY 9

   ...RAIN CHANCES REMAIN IN THE FORECAST THROUGH THE WEEKEND...

                  ...METEOROLOGICAL DISCUSSION...
The large scale pattern will change little over the next 5 days.  A
series of broad upper level Pacific storms will keep the WGRFC area
under a southwesterly flow aloft through the weekend.  Upper level
disturbances embedded in this southwesterly pattern will help
initiate the development of showers and thunderstorms over the WGRFC
area.  With deep moisture in place, locally heavy rainfall is
possible in the more organized thunderstorm complexes.

Precipitable Water (PW) values are running 150% to 200% of normal for
the western half of the WGRFC area.  Locally heavy rainfall is
expected across Southeast New Mexico and the Texas Rolling
Plains through Tuesday.  As the week progresses, the focus for heavy
rain will shift east toward North Central and Northeast Texas.
However, there are no large scale systems expected to "clear out" the
area.  Even if the focus for heavy rain shifts east, scattered
showers and thunderstorms remain in the forecast for all of the WGRFC
area through the weekend.

At this time, areas of Texas west of Interstate 35 are still
experiencing various stages of drought.  Same goes for most of New
Mexico and Southern Colorado.  Rainfall across these areas will
be most beneficial and should help with the ongoing drought.

For areas of Texas east of Interstate 35, soils remain fairly
saturated.  Forecast rainfall will likely produce runoff, and new
mainstem river flooding is a possibility, especially for the
Trinity, Neches, and Sabine Basins of North and East Texas.  Locally
heavy rainfall with any organized thunderstorms could potentially
produce significant river flooding on the smaller basins.

We will need to monitor this situation for possible flooding later
this week.

                    ...PRECIPITATION FORECAST...
For Today into Tuesday morning, Mean Areal Precipitation (MAP)
amounts of 2 to 3 inches are forecast for portions of West Texas
between Midland and Lubbock.  MAP amounts of 1 to 2 inches are
forecast from the Texas Panhandle to the Permian Basin, westward into
Eastern New Mexico.  MAP amounts of 0.25 to 0.50 inch are forecast
for the remainder of Texas west of the Heartland and for the
remainder of New Mexico.

For Tuesday into Wednesday morning, MAP amounts of 1 to 1.50 inches
are forecast for North Central Texas and for the Texas Panhandle.
MAP amounts of 0.25 to 0.50 inch are forecast for the remainder of
the WGRFC area.

For Wednesday into Thursday morning, MAP amounts of 0.25 to 0.50 inch
are forecast for North Central Texas.  Lighter MAP amounts are
forecast for the remainder of the WGRFC area.

For Thursday into Saturday morning, MAP amounts of 1 to 1.50 inches
are forecast for North Central and Central Texas.  MAP amounts of
0.25 to 0.50 inch are forecast for the remainder of the WGRFC area.

Moderate or worse drought conditions continue across parts of New
Mexico and Texas. Recent precipitation events have brought drought
relief to parts of Texas.  In Texas, about a third of the state is
experiencing moderate or worse drought (31%), and about 6% has
extreme to exceptional drought conditions. In New Mexico, a little
over half of the state is experiencing moderate or worse drought
(56%). Lake levels in the extreme drought areas of Texas have
responded some, but many are at or near historical lows for this time
of year.  The rainfall expected over the next five days over the WGRFC
area will likely be heavy enough to produce significant runoff over
roughly the eastern half of the WGRFC area.

                     ...HYDROLOGIC DISCUSSION...
...Neches Basin...
...Minor Flooding...
Minor flooding continues along the mainstem of the Neches and Angelina
River system. The tributaries have recovered from the last flood event,
but the water is still slowly working its way downstream.  Area lakes
remain full and flood control reservoirs continue their releases. The
stage on the Neches River near Town Bluff (TBFT2) is being driven by
releases out of B.A. Steinhagen lake.

...Sabine Basin...
...Minor Flooding...
Toledo Bend will continue full 2-unit continuous power generation
producing approx 15,000 cfs outflow; therefore, Deweyville (DWYT2) will
remain above minor flood levels through the week. The river system
remains saturated and the short break from rainfall will not be long
enough to fully recover before the next round of flooding will begin
late Tuesday and Wednesday.

...Trinity Basin...
...Higher Flow Non-Flood Forecasts...
Lake Livingston continues to remain full and is passing any extra water
from upstream through it`s flood gates. Points downstream will remain
well above base flow until further notice.

...Brazos Basin...
...Higher Flow Non-Flood Forecasts...
The Navasota River tributary is still recovering from last weeks
rainfall, but the river is no longer in flood. That will not last long,
though, as additional rises are expected to develop in the upper
portions of the Normangee River system later this week.

...Remainder of WGRFC Basins...
Minor flooding continues in the Neches and lower Sabine River basins.
No significant rainfall sufficient to cause additional  flooding is
expected until Tuesday/Wednesday when the next upper level system
starts developing several rounds of precipitation as it slowly moves
eastward. The favored areas for now would be the Trinity  River basin
in and around Dallas and the uppermost section of the Sabine and Neches
Rivers, though beneficial rains are expected in the upper Brazos and
upper Colorado basins as well.

              ...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

WALLER


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