Hydrometeorological Discussion
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AGUS74 KFWR 181659
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1158 AM CDT THU SEP 18 2014

               VALID SEPTEMBER 18 THROUGH SEPTEMBER 23

...WIDESPREAD RAIN EXPECTED THE NEXT FIVE DAYS, WITH SIGNIFICANT
RAINFALL FORECAST OVER PORTIONS OF NEW MEXICO AND WEST TEXAS...

                   ...METEOROLOGICAL DISCUSSION...

Weak upper air disturbances, combined with an old frontal boundary,
have kept scattered to numerous showers ongoing across most of the
WGRFC area the past three days. In general, the upper level pattern is
conducive for precipitation to continue through the remainder of the
five-day forecast period. In east Texas, the best chances for rain
will be during the next 24 hours over central into southeast Texas.
Some significant flooding is possible at this time, but most locations
will only see minor flood stages.  Very heavy rainfall fell early
Thursday morning over central Texas where 6 to 7 inches of rain fell
from Dripping Springs through Austin to near Georgetown TX.  Locally
heavy rainfall is occurring over the Houston area now.

The other focus for rainfall continues to be on the remnants of
Hurricane Odile which are west northwest of El Paso this morning.
Locally heavy rain of over 3 inches fell over the Texas panhandle
near Olton TX the past 24 hours ahead of this storm, and nearly 3
inches of rain fell southeast of El Paso. Over the next several days,
the remnants of Odile are expected to move over east central New
Mexico tonight into Friday morning, then will slowly move across the
Texas panhandle.  Abundant moisture is in place over the area, and
the widespread rain will continue over southern and eastern New Mexico
and will continue over west Texas and the Texas panhandle as well.
These remnants will interact with the moisture through the weekend to
allow rainfall to impact the western parts of the WGRFC area as the
storm slows.  Flash flooding will continue to remain the greatest
concern.  The possibility of some minor and perhaps moderate flooding
during the next two days exists.  Rainfall is also expected into early
next week, especially over west central and northwest Texas, depending
upon the future track of Odile`s remnants. Outside of west Texas,
light to moderate rain is expected over a good part of Texas as
moisture is drawn northward from the Gulf of Mexico.  We will continue
to monitor the progress of this storm.

By Monday a weak cold front is forecast to move into north Texas.  At
this point significant rainfall is not expected with the frontal
boundary as the remnants of Odile eventually dissipate.

                    ...PRECIPITATION FORECAST...
For Today into Friday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 inch or more are forecast for much of New Mexico into
western, central and southeastern Texas and into southwestern
Louisiana. The heaviest rain, with MAP amounts of 3.00 inches, are
forecast over a small part of eastern New Mexico.  MAP amounts of
2.00 inches are forecast over southeast Texas in and around Houston.
Lighter amounts of MAP are forecast over most of Texas, most of New
Mexico and Louisiana.

For Friday into Saturday morning, MAP amounts of 0.25 inch or more are
forecast for the northeast third of New Mexico into western and
southern Texas.  The heaviest rain, with MAP amounts of 1.50 inches,
are forecast over northeast New Mexico into the Texas panhandle.
Lighter amounts of MAP are forecast over most of Texas, most of New
Mexico, and southwestern Louisiana.

For Saturday into Sunday morning, MAP amounts of 0.25 inch or more are
forecast for eastern New Mexico into western, central and southern
Texas.  The heaviest rain, with MAP amounts of 1.00 inch, are forecast
from eastern New Mexico into the Texas panhandle.  Lighter amounts of
MAP are forecast over much of the remaining sections of the WGRFC
area.

For Sunday into Tuesday morning, MAP amounts of 0.25 inch or more are
forecast for most of New Mexico, the northwest two thirds of Texas,
and Colorado.  The heaviest rain, with MAP amounts of 2.00 inches,
are forecast over the Texas panhandle.  Lighter amounts of MAP
are forecast over the remaining sections of the WGRFC area.

Drought persists but is slowly improving over Texas and New Mexico.
Statewide, New Mexico has no areas of exceptional drought, while less
than 2% of Texas remains in exceptional drought. Severe drought
conditions are impacting less than 40% of New Mexico and 35% of
Texas.  No doubt the rainfall forecast the next 5 days will
further alleviate some of the ongoing drought. Runoff is expected
across southeast and central Texas, as well as over eastern New
Mexico for the next 5 days.  Runoff leading to significant mainstem
river flooding may occur on the upper Rio Grande and Pecos Rivers to
go along with flash flooding in New Mexico.  The runoff in south
and southeast Texas may lead to additional river flooding.  No
significant runoff is expected over north central and northeast Texas.

                     ...HYDROLOGIC DISCUSSION...
...Colorado Basin...
...Moderate Flooding...
The primary rise was the heavy rainfall occurring near Austin causing
Onion Creek (ATIT2) to race up to moderate flood stage.  This is a
rapid rise and fall situation as the flood wave should push through
shortly after noon.  In addition, LCRA is releasing 11,000 cfs from
Tom Miller Dam which will push several sites downstream into action
stage. With these elevated flows, any additional rainfall over
these watersheds could cause more significant flooding over the
next couple of days.

...San Bernard Basin...
...Higher Flow Non-Flood Forecasts...
Widespread 1 - 1.5 inches of rain have fallen across the upper San
Bernard River basin (EBBT2) and extreme lower end around Sweeney
(SWYT2).  While rainfall continues and expected to continue through
the day and overnight, minor flood conditions are not expected to
result at this time.

...Guadalupe Basin...
...Higher Flow Non-Flood Forecasts...
Significant rainfall that impacted the lower Colorado River also
impacted parts of the Guadalupe basin, specifically Plum Creek near
Luling receiving around 4 inches in 6 hours.  The water is still
working its way to the gage but should push the creek into Action
stage.  Will continue to monitor as this water makes its way towards
the gage.

...Rio Grande Basin...
...Higher Flow Non-Flood Forecasts...
From Caballo Reservoir through El Paso, widespread 1-1.5 inches of
rain has generated higher, non-flood flows along the Rio Grande.
Further downstream at the confluence with the Rio Conchos, due to
releases from Luis Leon Reservoir, Presidio (PRST2) and other
downstream locations will see higher, non-flood flows.  Expected
duration and release changes are not known at this time.
Additionally, the higher flows routed along the mainstem from El Paso
will arrive early next week to continue river rises along the Big
Bend locations, but at this time, not expected to reach minor flood
levels.

...Remainder of WGRFC Basins...
Rainfall occurring across many parts of WGRFC with soil states
nearing saturation for the Gulf Coast area including the Neches
and San Jacinto.  San Jacinto in particular could see rises in
the near future that would produce forecasts and is being monitored
closely.  Elsewhere, the Pecos River is also seeing soil states
rise towards saturation from the remnants of Odile and could see
out of bank flow in the near future, but currently rises are
forecasted to stay within banks.  The rest of the WGRFC will see
precipitation in some form of intensity, but the current forecast
displays no rises past criteria.


              ...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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