Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 191712
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1111 AM CST SUN FEB 19 2017

                VALID FEBRUARY 19 THROUGH FEBRUARY 24

...LARGE STORM SYSTEM TO BRING WIDESPREAD RAIN TO MUCH OF THE WGRFC
AREA THE NEXT FEW DAYS...

                   ...METEOROLOGICAL DISCUSSION...

A ridge of high pressure extends along the Texas/Louisiana border
this morning.  As this ridge moved across Texas the past 24 hours
it temporarily brought warm and dry conditions to the WGRFC area.

A significant rainfall event is shaping up for the next couple days.
The most favored area for locally heavy rains appears to be across
southeast Texas and southern Louisiana.  A large elongated trough of
low pressure is over the southwestern U.S. now, centered on central
Arizona. This storm will be moving eastward and should be centered
over far west Texas and northern Mexico by Monday morning.
Thereafter, this long trough will be moving slowly eastward across
the WGRFC area, and by Tuesday morning it will extend across eastern
Texas to a closed low pressure system along the Texas Gulf coast.
Precipitation is expected to develop this afternoon mainly along and
west of the I-35 corridor.  Precipitation is then expected to become
heavier and more widespread as the area moves eastward into the
overnight hours tonight into Monday.  The heaviest rain should focus
along a surface boundary where the atmospheric moisture will be
deepest over southeast Texas and southern Louisiana, but isolated
heavier amounts will be possible anywhere over the eastern half of
Texas. The upper low will continue to move slowly over the
northwestern Gulf of Mexico Tuesday, just far enough eastward to
produce the heaviest rainfall over Louisiana on Tuesday. This
low should eventually move far enough east so that all of the
rainfall ends over the WGRFC area by Wednesday morning.  At this
time, maximum rainfall amounts of 3 to 5.00 inches are possible
for areas across east Texas. Widespread amounts of 2 to 3 inches
can be expected for primarily the eastern half of Texas and Louisiana
during this event. We will continue to monitor any changes in the
movement of this storm and adjust the expected impacts accordingly.

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
and continuing through Thursday into Friday morning.  There will be a
weak storm system which will move quickly across northern New Mexico
and southern Colorado Thursday.  This disturbance may begin to
spread some light rain and snow into the higher elevations of
northern New Mexico and southwest Colorado late Wednesday night into
Thursday, but is not forecast to impact the remainder of the WGRFC
area.

                    ...PRECIPITATION FORECAST...
For Today into Monday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 inch or more are forecast for most of the eastern two
thirds of Texas, as well as over northern New Mexico into southwest
Colorado.  The heaviest rain, with MAP amounts of up to 3.00 inches,
are forecast north of Corpus Christi southeast of San Antonio TX.
MAP amounts of less than 0.25 of an inch are forecast over most of
the WGRFC area of responsibility.

For Monday into Tuesday morning, MAP amounts of 0.25 inch or more
are forecast for the eastern half 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
Orange TX.  MAP amounts of less than 0.25 of an inch are forecast
over the southeastern two thirds 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 eastern quarter of Texas, Louisiana,
as well as over northwestern New Mexico into western Colorado.

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

In spite of recent rainfall, the latest U.S. Drought Monitor for
Texas continues to show the area considered to be abnormally dry is
at 12%.  Also, 4% of Texas is experiencing moderate drought
conditions and 1% is 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 the next 5 days will likely result in runoff.  Significant
runoff will occur over those basins in east and southeast Texas
where heavy rain falls in short durations, which will likely result
in minor to perhaps moderate mainstem river flooding.

                     ...HYDROLOGIC DISCUSSION...
...WGRFC Basins...
Rivers are near baseflow, but the soils do remain saturated along the
Gulf Coast.  More rainfall in the forecast over these basins could
generate flooding early this week.  Similar amounts over the same
area will have higher responses than last week due to the current
soil conditions.   Other areas in Central and Eastern Texas could see
minor flooding impacts as this system moves through into Tuesday.

              ...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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