Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 201704
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1103 AM CST MON FEB 20 2017

                VALID FEBRUARY 20 THROUGH FEBRUARY 25

...THE LARGE STORM SYSTEM WHICH BROUGHT WIDESPREAD RAIN TO MUCH
OF TEXAS WILL END FOLLOWED BY DRY CONDITIONS THE NEXT FEW DAYS...

                   ...METEOROLOGICAL DISCUSSION...

A large elongated trough of low pressure is centered over far west
Texas and northern Mexico this morning.  Precipitation developed
Sunday afternoon in Texas west of the I-35 corridor.  The showers
and thunderstorms became heavier and more widespread as the area
moved eastward Sunday night and this morning.  The heaviest rain
fell along the leading edge of the Texas Hill Country where the
atmospheric moisture was deepest.  Rainfall amounts of over 4.00
inches were noted on the west side of San Antonio.  Widespread
amounts of 2 to 3 inches occurred over the western parts of north
Texas, as well as over south central, southeast and deep south Texas.

This long trough will be moving slowly eastward across Texas today,
and by Tuesday morning it will extend across eastern Texas where a
closed low pressure system is forecast to form west of Shreveport LA.
The widespread rain over east Texas now will move east tonight.  The
upper low will continue to move east over Louisiana Tuesday and may
produce some residual rainfall over east Texas and western Louisiana.
Any rain that does form will move east of our region by late
Tuesday.

A ridge of high pressure is forecast to build over Texas which will
bring dry weather conditions to most of the WGRFC area by Wednesday
morning.  The ridge will continue to bring dry weather into Thursday.

A weak storm system will be moving quickly out of Utah Thursday and
across northern New Mexico and southern Colorado Thursday night.
This disturbance may spread some light rain and snow into the higher
elevations of northwestern New Mexico and southwest Colorado late
Wednesday night into Thursday, but is not forecast to impact the
remainder of the WGRFC area. In fact, on Friday a strong zonal flow
of air is forecast to develop across the WGRFC area.  This zonal
flow is very dry, thus no rainfall is forecast from Friday into
Saturday.

                    ...PRECIPITATION FORECAST...
For Today into Tuesday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 inch or more are forecast for the eastern third of
Texas into Louisiana.  The heaviest rain, with MAP amounts of up to
3.00 inches, are forecast over portions of extreme southeast Texas
around Houston and near Winnie TX.  MAP amounts of less than 0.25 of
an inch are forecast over the eastern half of Texas.

For Tuesday into Wednesday morning, no significant MAP amounts are
forecast for the WGRFC area.  MAP amounts of less than 0.25 of an
inch are forecast over the southeastern quarter of Texas, Louisiana,
as well as over extreme northern New Mexico into southwestern
Colorado.

For Wednesday into Thursday morning, no significant MAP amounts are
forecast for the WGRFC area.  MAP amounts of less than 0.25 of an
inch are forecast over northwestern New Mexico into western Colorado.

For Thursday into Saturday morning, no significant MAP amounts are
forecast for the WGRFC area.  MAP amounts of less than 0.25 of an
inch are forecast over extreme northern New Mexico into southwestern
Colorado.

Rainfall from the past 24 hours and from last week has no doubt
improved the soil moisture conditions across much of Texas. The
last U.S. Drought Monitor for Texas showed the area considered to be
abnormally dry was at 12%.  Also, 4% of Texas was experiencing
moderate drought conditions and 1% was in severe drought. In New
Mexico the drought monitor shows around 12% of the state experiencing
abnormally dry conditions, with 2% remaining in moderate drought. The
rainfall forecast today will likely result in significant runoff over
southeast Texas.  No new or additional runoff is expected elsewhere.
After today, no runoff is expected over the WGRFC area.

                     ...HYDROLOGIC DISCUSSION...
...San Antonio Basin...
...Moderate Flooding...
Widespread light rain with locally heavy amounts occurred over parts of
the San Antonio River Basin.  The San Antonio River at Elmendorf
(ELMT2) is forecast to reach moderate flood levels.  The San Antonio
River near Floresville (FLVT2) and Runge (SRRT2) are forecast to reach
minor flood levels.  The remainder of the San Antonio River system will
remain at higher than normal flow levels.

...Guadalupe Basin...
...Minor Flooding...
Widespread light rain with locally heavy amounts occurred over parts of
the Guadalupe River Basin.  The lower Guadalupe River at DuPont
(DUPT2) is forecast to crest around flood stage.  The remainder of
the Guadalupe is expected to remain below flood criteria.

...Neches Basin...
...Minor Flooding...
Heavy rainfall occurred earlier this morning in portions of the Neches
River basin. Rainfall will be spreading across the entire
Neches basin over the course of the day. Minor flooding can be expected
at a few locations over the next couple of days.

...Sabine Basin...
...Minor Flooding...
Rainfall is entering the Sabine River basin this morning.  Minor
flooding is possible on smaller rivers and streams.

...Brazos Basin...
...Minor Flooding...
Widespread light rain with locally heavy amounts occurred over parts of
the Brazos River Basin.  This is causing higher than normal flows at
various locations.  Middle Yegua Creek at Dime Box (DMYT2) is forecast
to crest around flood stage.  The remainder of the Brazos is expected
to remain below flood criteria.

...San Jacinto Basin...
...Higher Flow Non-Flood Forecasts...
Local rainfall of around 2 inches did cause some responses, but no
flooding is expected.

...San Bernard Basin...
...Higher Flow Non-Flood Forecasts...
San Bernard did respond to the local runoff, but the amounts were not
high enough to generate any major rises.  East Bernard may reach minor
but all points should stay below minor flood.

...Lavaca-Navidad Basin...
...Higher Flow Non-Flood Forecasts...
Many of the sites did respond to the rainfall, but amounts stayed too
light to generate any significant flooding.  Expect out of bank flow
but no impacts for the area.

...Trinity Basin...
...Higher Flow Non-Flood Forecasts...
Crests near or above criteria can be expected on some smaller rivers
and streams during the next 24 hours throughout the Trinity River
basin.

Increasing inflows into Lake Livingston are likely as well, which will
lead to elevated flows on the mainstem Trinity below Lake
Livingston over the coming week. The river may reach criteria late week
at Liberty and Moss Bluff.

...Remainder of WGRFC Basins...
Majority of the rainfall from this event has moved through causing some
action and minor stage forecasts, but no significant flooding is
expected.  Most of Texas saw some beneficial rain which will keep soils
saturated for a bit, but with no heavy rain in the forecast no flooding
is expected in the forecast period.

              ...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.weather.gov/wgrfc/wgrfcfop

The West Gulf River Forecast Center is now on Facebook:
http://www.facebook.com/NWSWestGulf

National Precipitation Analysis:
http://water.weather.gov/precip/

The forecast rainfall amounts (QPF) can be viewed on our webpage at:
http://www.weather.gov/wgrfc/wgrfcqpfpage

The US Drought Assessment:
http://www.cpc.ncep.noaa.gov/products/Drought

The latest on Reservoir Information for Texas:
http://www.waterdatafortexas.org/reservoirs/statewide

STORY

$$




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