Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 261739
1139 AM CST THU NOV 26 2015



                  ...METEOROLOGICAL DISCUSSION...
A major storm system has formed to the west of the WGRFC area.  At
the surface, a moist southerly flow of Gulf moisture is occurring,
with high level moisture also present from the eastern Pacific
Ocean.  As this moisture increased the past 24 hours, light showers
developed over central and south Texas, as well as over parts of
New Mexico and Colorado.  Higher elevation snow can be expected
today over the mountains of northern New Mexico and Colorado, and
this snow should continue the next few days. A mixture of wintry
precipitation is possible at lower elevations from eastern New
Mexico through the Texas panhandle into western Oklahoma the next
few days.

More significant rainfall begins later today over most of Texas.  A
strong upper level low pressure system is located over northwestern
Utah this morning. This low is forecast to remain steady or even
shift westward through Saturday before moving northeastward to
Wyoming on Monday of next week. Southwesterly flow has developed
aloft over the WGRFC area of responsibility and will persist through
the weekend. Due to the persistence of this flow a prolonged
precipitation event is about to begin.   At the surface, a strong
cold front is expected to enter the western parts of North Texas
today and then move slowly across the state on Friday. The cold
front and upper level pattern will combine to produce conditions
favorable for locally heavy rainfall over much of the WGRFC area,
especially over north Texas, along an behind the front through Monday

In addition, the weather models are also forecasting that eastern
Pacific Hurricane Sandra will move over southwestern Mexico as a
tropical storm on Saturday before dissipating over land as it moves
northeastward on Sunday. This system could cause some additional
moisture to interact with the upper level storm system and cold front
to enhance the heavy rainfall threat in Texas and western Louisiana
through Sunday.

In general, rainfall amounts of up to 8.00 inches are expected for
areas along and north of I-20 from late today through Sunday, with
the highest amounts near the Red River. Amounts of over 4.00 inches
will be widespread across central and north Texas. We will continue
to monitor the model guidance for any changes, and will update

Drier air from the west should shut down the prospects of
significant rainfall on Monday into Tuesday morning as the upper low
shifts eastward over Nebraska and Iowa.

                    ...PRECIPITATION FORECAST...
For Today into Friday morning, Mean Areal Precipitation (MAP) amounts
of 0.25 to 1 inch are forecast for portions of southern Colorado,
eastern and southern New Mexico, and the northwestern two thirds of
Texas. The heaviest rain, with MAP amounts of 2 to 4 inches, are
forecast for portions of North Texas especially along the Red River.
MAP amounts of less than 0.25 inch are forecast for most of the rest
of Texas and New Mexico.

For Friday into Saturday morning, MAP amounts of 0.25 to 1 inch are
forecast for most of southern Colorado into northern New Mexico, and
from the southeastern third of New Mexico into most of the rest of
Texas.  The heaviest rain, with MAP amounts of 2 to 4 inches, are
forecast from north central and northeastern Texas into eastern
Oklahoma.  MAP amounts of less than 0.25 inch are forecast for the
rest of the WGRFC area.

For Saturday into Sunday morning, MAP amounts of 0.25 to 0.50 inch
are forecast for a good portion of Texas from the Big Bend through
the Hill Country to northeast Texas.  The heaviest rain, with MAP
amounts of 1.50 to 2.00 inches, are forecast for most from central
into northeastern Texas.  MAP amounts of less than 0.25 inch are
forecast for most of the rest of the WGRFC area.

For Sunday into Tuesday morning, MAP amounts of 0.25 to 0.50 inch are
forecast for central and east Texas into most of Louisiana.   MAP
amounts of less than 0.25 inch are forecast for most of the rest of
Texas, northeast New Mexico and southern Colorado.

Topsoil moisture has increased significantly with 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 come to an end, 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 8 inches are forecast over several days from late today
through the weekend. This likely will lead to some potentially
significant runoff because of the wet soil moisture and cold season
vegetation patterns.

                     ...HYDROLOGIC DISCUSSION...
...Trinity Basin...
...Minor Flooding...
River stages continue to fall across the lower Trinity River. Minor
flooding is still occurring downstream at Moss Bluff (MBFT2).

...Neches Basin...
...Minor Flooding...
Minor flooding continues at various locations across the Neches
River basin.  River stages are falling.  However, heavy rainfall is
anticipated Friday through Saturday which may cause higher levels of
flooding in the headwater basins.

...Sabine Basin...
...Minor Flooding...
Toledo Bend Reservoir will continue  generating power 24 hours per
day until further notice at one unit of power generation.
Additional heavy rainfall is expected Friday through Saturday which
could cause significant flooding in the upper Sabine.

...Brazos Basin...
...Higher Flow Non-Flood Forecasts...
Higher flows are occurring on the Navasota River and lower Brazos
River.  River stages have crested and continue receding.

...Remainder of WGRFC Basins...
Additional heavy rainfall  is expected Friday through Sunday that
could cause another round of flooding in the headwaters of the
Sabine, Neches and portions of the Trinity and Brazos.

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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