Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 201642
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1142 AM CDT FRI OCT 20 2017

                 VALID OCTOBER 20 THROUGH OCTOBER 25

...SHOWERS AND THUNDERSTORMS EXPECTED ACROSS NORTH AND EAST TEXAS
THIS WEEKEND BEFORE IT TURNS DRY NEXT WEEK...

                   ...METEOROLOGICAL DISCUSSION...
An upper level ridge of high pressure has dominated our weather the
past several days and brought the region dry weather.  This morning
this upper ridge is moving across the Southeastern US. With this
ridge moving eastward, it has allowed storm systems to our west to
approach the WGRFC area.  In fact the next precipitation episode has
begun.  An upper level disturbance has moved from the Texas Big Bend
into central Texas. This has created showers and thunderstorms in two
areas. One area was across southern New Mexico into west Texas.  The
other area was from the upper Texas Gulf coast into much of east
Texas.  In fact, locally heavy rain fell in the area around Houston
around sunrise this morning. As this disturbance passes across Texas
today showers and isolated thunderstorms will continue across the
eastern potions of the state.  The rain so far today was not heavy
enough to cause any river issues. Over the past 24 hours the largest
rainfall totals were noted south of Houston where the region from
Friendswood to League City received 4.50 to 5.50 inches. And out
west, the area south of Cloudcroft NM received 1.00 to 1.25 inches.

A stronger upper level storm system will approach the WGRFC area
Saturday.  This storm will move quickly through Texas and western
Louisiana Saturday night and Sunday.  This disturbance will push a
strong cold front across the region Saturday night through Sunday
morning and showers and strong thunderstorms are expected along and
ahead of this front.  Although the front will be very progressive,
rainfall amounts of up to 2.00 inches are possible across north
central and northeast Texas late Saturday night into Sunday morning.
Some flash flooding is possible across low lying areas where the rain
rates are highest, and river rises are possible. However, no
significant river flooding is expected at this time.  This storm
should move east of the WGRFC area by Sunday evening and the rainfall
will end.

A ridge of high pressure will be forming west of the WGRFC area later
Sunday. Since this ridge will move little through the next week, no
rainfall is expected.  A secondary cold front is expected to move
across Texas later Tuesday, but no precipitation is expected with its
passage.

                    ...PRECIPITATION FORECAST...
For Today into Saturday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 to 0.50 inch are forecast for portions of east and
southeast Texas.  The heaviest rain, with MAP amounts of 1.00 inch,
are forecast over the upper Texas Gulf coast.  MAP amounts of less
than 0.25 of an inch are forecast over the eastern half of Texas into
western Louisiana, as well as over portions of west Texas.

For Saturday into Sunday morning, MAP amounts of 0.25 of an inch or
more are forecast over the eastern two thirds of Texas into
northwest Louisiana.  The heaviest rain, with MAP amounts of up to
2.00 inches, are forecast for areas over and northeast of the DFW
metroplex.  MAP amounts of less than 0.25 of an inch are forecast
over the southeastern two thirds of Texas into Louisiana, as well as
over portions of extreme northern New Mexico into southern Colorado.

For Sunday into Monday morning, MAP amounts of 0.25 to 0.50 inch are
forecast for portions of east Texas and Louisiana.  MAP amounts of
less than 0.25 of an inch are forecast over the southeastern half of
Texas into Louisiana.

For Monday into Wednesday morning, no significant MAP amounts are
forecast for the WGRFC area.

The latest U.S. Drought Monitor for Texas shows the area considered
to be abnormally dry is around 19%, and only 4% of Texas is
experiencing moderate drought conditions (mainly over extreme
northeast Texas). In New Mexico, 8% of the state is experiencing
abnormally dry conditions. The rainfall which is forecast over
the next 5 days may create runoff over portions of north Texas and
along and near the upper Texas Gulf coast.  If rain rates are fast
enough some river rises to criteria may occur.  Elsewhere, no
significant runoff is expected.

                     ...HYDROLOGIC DISCUSSION...
...Rio Grande Basin...
...Minor Flooding...
The Rio Grande above the Rio Conchos confluence (PIOT2) is slowly
falling and should fall below flood stage by this afternoon.

...Nueces Basin...
Lake Corpus Christi is releasing around 400 cfs, which has brought
all downstream points below criteria. The lake is holding steady
around its conservation pool of 94 feet.

...Remainder of WGRFC Basins...
The remainder of the rivers across the WGRFC area are currently below
criteria levels. Locally heavy rain today in southeastern Texas
should not cause any significant rises at river forecast points.
Smaller streams near the coast may see significant rises.  Rain this
weekend may cause some rises above criteria, most likely in northern
and northeastern Texas, but significant river flooding is not
forecast over the next 5 days.

              ...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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