Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 291733
1133 AM CST SUN NOV 29 2015



                  ...METEOROLOGICAL DISCUSSION...
A major storm system continues to be present to the northwest of the
WGRFC area. At the surface, deep Gulf moisture exists over most of
Texas, and aloft, high level moisture is also present from the
eastern Pacific Ocean.  As upper disturbances in the southwest flow
moved across the region the past 48 to 72 hours, widespread rain and
embedded thunderstorms developed over most of Texas, as well as over
the southeast half of New Mexico.  Higher elevation snows also
occurred over the mountains of southern Colorado, but the snow has
let up the past 24 hours.  However, some additional snow can be
expected over the mountains of northern New Mexico and Colorado
the next day or two. The heaviest rain the past 24 hours was over
west Texas, with around 2.00 inches noted around Abilene, Sweetwater
and Sterling City.

The rainfall that has been so persistent over most of Texas will
start to decrease by tonight. The strong upper level low pressure
system which was over Nevada will be redeveloping over Wyoming by
tonight.  As this transformation occurs drier air will begin to
move eastward over Texas. This will cause the rainfall over Texas to
get shoved eastward into Louisiana and will gradually diminish by
Monday morning.

In general, additional rainfall amounts of up to 1.00 inch are
expected for areas east of I-35 and north of I-20 through tonight,
with the highest amounts actually being over southwest Arkansas.  We
will continue to monitor the model guidance for any changes, and will
update accordingly.  Some parts of north Texas between Dallas and
Sherman has exceeded 10 inches of rain for this event.

On Monday the upper low will shift eastward, and by Tuesday morning
the low will be over extreme southern Minnesota.  Drier air should
cover a good part of the WGRFC area, but some residual rainfall
development can be expected from deep south into southeast Texas
and Louisiana from later Monday through Wednesday as the dry air
undercuts the lingering moisture.

On Wednesday an upper air disturbance will develop and approach
Texas from the northwest.  As this upper disturbance crosses
Texas rainfall should linger along and near the Texas Gulf coast.
After this disturbance moves east of the WGRFC area on Thursday all
the precipitation should push east of our region.  Dry weather is
then forecast Thursday through Friday morning.

                    ...PRECIPITATION FORECAST...
For Today into Monday morning, Mean Areal Precipitation (MAP) amounts
of 0.25 inch or more are forecast for central and northeast Texas
into northern Louisiana. The heaviest rain, with MAP amounts of 1.00
inch, are forecast over extreme northeast Texas.  MAP amounts of
0.25 of an inch or less are forecast for most of the rest of Texas,
western Louisiana, northern New Mexico and southern Colorado.

For Monday into Tuesday morning, no significant MAP amounts are
forecast for the WGRFC area.  MAP amounts of less than 0.25 inch are
forecast for the southeast third of Texas and Louisiana, as well as a
small part of northern New Mexico into southern Colorado.

For Tuesday into Wednesday morning, MAP amounts of 0.25 inch are
forecast over the middle and upper Texas Gulf coast into southern
Louisiana. MAP amounts of less than 0.25 inch are forecast for the
southeast third of Texas and Louisiana.

For Wednesday into Friday morning, MAP amounts of 0.25 inch are
forecast over deep south Texas, as well as for the Gulf coast of
Texas into southwest Louisiana. MAP amounts of less than 0.25 inch
are forecast for the southern third of Texas and the
southern half of Louisiana.

Topsoil moisture is very high due to recent rainfall events, which
means it will require less rainfall for runoff to occur. That, along
with the vegetation being dormant now that the growing season has
ended, means runoff will be quicker. Over Texas only 7% of the state
is abnormally dry, while over New Mexico, 26% of the state is
abnormally dry. Heavy rainfall amounts of up to 1 inch, on top of
what rain has already fallen, are forecast through tonight.  This
will lead to some additional runoff because of the wet soil moisture
conditions and the cold season vegetation patterns.

                     ...HYDROLOGIC DISCUSSION...
...Trinity Basin...
...Major Flooding...
Continued rains have pushed several sites into flood levels. Many of
the Trinity tributaries are experiencing minor to moderate flooding
with the additional rains.  The Trinity mainstem at Dallas  (DALT2)
crested above major flood levels at 41 feet yesterday.  It is
expected to remain at moderate flood levels for a couple of days
during a slow recession.  Points downstream from Trinidad (TDDT2)
through  Long Lake (LOLT2) have risen or forecast to rise slightly
into major flood levels for a few days.

It has been reported that a levee has been breached about a mile
upstream of Rosser and is affecting the area around Highway 34 and
other local roads.  These roads will be barricaded while river
levels remain high.

...Brazos Basin...
...Moderate Flooding...
Significant rainfall has generated rises on the Brazos River basin.
At this time, minor to moderate river flooding is occurring around
the De Leon basins of the Sabana and Leon Rivers.  Minor river
flooding is also occurring between Possum Kingdom and Granbury
Reservoirs.   Continued higher flows are expected as the threat for
rainfall continue into next week.

...Sabine Basin...
...Moderate Flooding...
Continued rainfall in the upper Sabine will push Greenville (GNVT2)
and Quinlan (QLAT2) into minor flood levels.  Routed water and local
runoff are pushing Mineola (MLAT2) and Gladewater (GDWT2) into
moderate flood levels and expected to remain high for a few days.

...Rio Grande Basin...
...Minor Flooding...
The Rio Grande above the confluence with the Rio Conchos (PIOT2) has
responded to local rains and is fluctuating around minor flood
levels.  The river should crest slightly below minor flood levels
today and then recede.

...Neches Basin...
...Minor Flooding...
Minor flooding is expected on the Neches River from Lake Palestine to
Alto.  Continued rainfall may prolong the higher river levels.

...Remainder of WGRFC Basins...
Additional rainfall is expected tonight through Monday but is not
expected to cause another round of flooding

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:

The Flood Potential Outlook can be viewed on our webpage at:

The West Gulf River Forecast Center is now on Facebook:

National Precipitation Analysis:

The forecast rainfall amounts (QPF) can be viewed on our webpage at:

The US Drought Assessment:

The latest on Reservoir Information for Texas:



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