Issued by NWS West Gulf RFC
AGUS74 KFWR 201714
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1114 AM CST FRI DEC 20 2013
VALID DECEMBER 20 THROUGH DECEMBER 25
...SIGNIFICANT PRECIPITATION LIKELY THE NEXT TWO DAYS, THEN DRY
WEATHER IS EXPECTED UP TO CHRISTMAS MORNING...
A large low pressure system is located over the Baja of California
this morning. This low is moving eastward, causing low level
moisture to surge into the area as southerly surface winds are
tapping into the Gulf of Mexico. Aloft, a more southwesterly flow
is also tapping into deep tropical moisture from the Pacific. This
pattern of Pacific moisture transport, sometimes called the
Pineapple Express, is setting up a favorable environment for
precipitation for the WGRFC area. Rainfall is already beginning to
form over southern New Mexico into western and northern Texas.
All of this moisture is waiting for a southward moving cold front to
arrive, which happens to be moving into north Texas now. As the
upper low moves into southern New Mexico Saturday morning, the front
will temporarily stall across central and northeast Texas. This
will help provide the focus for the development of showers and
thunderstorms. All of these factors are pointing to a large
area of the WGRFC area receiving precipitation, with some of the rain
being locally heavy over northern and eastern Texas. This rain
activity will be widespread Friday night, then shift east Saturday
ahead of the upper level storm system. Soils remains somewhat
saturated from recent events as cooler temperatures and dormant
vegetation are helping to keep the evapotranspiration low. At this
time, this rainfall event is expected to generate river responses
over the eastern half of Texas. We will continue to monitor and
will update accordingly.
By Sunday the upper low will be moving away from the WGRFC area over
Illinois. A secondary trough of low pressure will cross Texas, but
most of the moisture will have been swept eastward so no additional
precipitation is expected.
On Monday a large ridge of high pressure is forecast to move across
the western US toward Texas. This will bring cool, dry air into the
WGRFC area, with dry conditions expected Monday through Wednesday
For Today into Saturday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 of an inch or more are forecast over the northwest
half of Texas and southern New Mexico. The heaviest rain, with MAP
amounts of 1.50 inches, are forecast near the Midland/Odessa area as
well as over southeast Oklahoma. MAP amounts of 1.00 inch are
forecast for much of northern and western Texas. Lighter MAP
amounts are forecast for most of the remainder of the WGRFC area.
For Saturday into Sunday morning, MAP amounts of 0.25 inch or more
are forecast over the Texas panhandle, as well as over the eastern
third of Texas and Louisiana. The heaviest rain, with MAP amounts
of 1 to 2 inches, are forecast for northeast Texas into Arkansas.
Lighter MAP amounts are expected for most of the remainder of the
For Sunday into Monday morning, no significant MAP amounts are
forecast for the WGRFC area. MAP amounts of 0.25 inch or less are
forecast for northeast New Mexico into southern Colorado.
For Monday into Wednesday morning, no significant MAP amounts are
forecast for the WGRFC area.
The drought situation in Texas has shown some improvement in recent
months, with less than 7% of the state now in extreme drought. New
Mexico has improved as well with only 4% of that state in extreme
drought. However, all of New Mexico and 74% of Texas still remain in
some level of drought category. The forecast rainfall could help the
drought conditions across southeast New Mexico into western and
northern Texas. Reservoir data in Texas indicates a significant
improvement during the past few months in some areas of Texas,
particularly in eastern Texas and on the Nueces and Guadalupe Rivers
in southern and central Texas. However, reservoirs on the Frio
River, Medina River, Colorado River (especially the highland lakes
and upstream), Brazos River, and upper Trinity River are typically
below levels one year ago at this time and comparable to levels in
December 2011. Some reservoirs in these areas are lower than in
2011. Minor to moderate runoff can be expected where the rain is
heaviest and the soils are the wettest, especially over northeast
Texas, the next 5 days.
All WGRFC area rivers are below bank full. Rainfall is expected
today and tomorrow across a large area of Texas with the heavier
amounts located over north and east Texas. Rainfall amounts could
cause isolated flood conditions mainly in the headwaters of the
upper Trinity, upper Sabine, and upper Neches river basins. Soil
conditions remain fairly saturated in these basins due to recent
precipitation. This along with less vegetation during the winter
months will increase the likelihood of surface runoff. However,
widespread flooding with significant mainstem rises are not expected
at this time.
...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:
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: