Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 281535
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1034 AM CDT WED SEP 28 2016

                VALID SEPTEMBER 28 THROUGH OCTOBER 3

...EXCEPT FOR THE FAR WESTERN PORTIONS OF THE WGRFC AREA, DRY
WEATHER CAN BE EXPECTED THE REST OF THE WEEK AND THE WEEKEND...

                  ...METEOROLOGICAL DISCUSSION...

A trough of low pressure lies along the lower Texas Gulf coast into
northeast Mexico this morning, and this trough has produced heavy
rain just offshore from South Padre Island. Some of this rain did
move onshore over Deep South Texas the past 24 hours, with maximum
amounts of nearly 2.50 inches observed near Laguna Vista TX.  This
rain is expected to work its way southwest out of Texas within the
next 24 hours, and it is doubtful the rain will get far enough inland
to have an adverse affect on the Rio Grande.

The upper level low pressure system that brought the region
widespread rainfall earlier this week has weakened and has moved
north over southern California this morning. Because of this the
low will no longer have much influence on the weather over the WGRFC
area.

Meanwhile, a strong low pressure system is located over Lake Michigan
east of Milwaukee.  This low pushed a cold front across Texas the
past two days. This front has ushered in some cooler, drier air into
much of the WGRFC region.  This much drier and noticeably cooler
weather is expected for the rest of the week. The low pressure system
over the Great Lakes is forecast to drop southward to Kentucky and
will deepen on Thursday.  This will cause a ridge of high pressure to
build over west Texas. The low over the Ohio valley will remain
nearly stationary through Saturday morning, and so will the ridge.
Because of the location of the ridge, any showers and thunderstorms
that develop today or beyond will be confined to far west Texas,
northern Mexico, western New Mexico and southwest Colorado. Dry
weather is forecast over the remainder of Texas and Louisiana through
Saturday.

By Sunday morning the low pressure system will move northeast into
the eastern Great Lakes region.  This will bring a more zonal flow of
air late this weekend into early next week.  Even with this change,
the next major storm system will not be approaching the WGRFC area
until Monday and Tuesday of next week, so mostly dry weather
conditions will persist until then.

                    ...PRECIPITATION FORECAST...
For Today into Thursday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 to 0.50 inch are forecast for portions of the lower
Texas Gulf coast of Deep South Texas.  MAP amounts of less than 0.25
of an inch are forecast for Deep South Texas, parts of northern
Mexico, western New Mexico and extreme southwest Colorado.

For Thursday into Friday morning, MAP amounts of 0.25 to 0.50 inch
are forecast for portions of extreme western New Mexico and southwest
Colorado.  MAP amounts of less than 0.25 of an inch are forecast for
the Mexican Gulf coast, northern Mexico, the western third of New
Mexico and western Colorado.

For Friday 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 for far west Texas, the western two thirds of New
Mexico and western Colorado.

For Saturday into Monday morning, no significant MAP amounts are
forecast for the WGRFC area.  MAP amounts of less than 0.25 of an
inch are forecast for much of Colorado.

Because of the widespread rain over the past few weeks over parts
of New Mexico and Texas, drought conditions are minimal. The U.S.
Drought Monitor categorizes Texas as 4.5% abnormally dry, with
almost 1% in severe drought. New Mexico remains unchanged this
week with 47% of the state abnormally dry and 4% in the moderate
drought category. The rainfall forecast over Deep South Texas
today will be too close to the coast to create runoff in the Rio
Grande.  Elsewhere, no significant runoff is expected the next 5
days.

                     ...HYDROLOGIC DISCUSSION...
...Nueces Basin...
...Major Flooding...
Large flood waves moved through the West Fork of the Nueces, Frio
River, and the mainstem Nueces on Monday. This water will take
a route downstream through the escarpment and out into the coastal
plains.  While the Frio River water will end up in Choke Canyon
Reservoir which is well below conservation pool, the mainstem wave
will take several weeks to route to Three Rivers and eventually Lake
Corpus Christi. The water at Asherton appears to be attenuating more
than originally expected but still may reach major flood.

...San Antonio Basin...
...Minor Flooding...
Today the flood crest has moved passed Floresville and continues
downstream towards Falls City.  This wave will continue to move down
the river this week causing nothing more than minor flooding as it
progresses.  No further rainfall is expected to impact this flood wave.

...Remainder of WGRFC Basins...
All other rivers, while wetter than normal for most of the area, are
mostly inside their banks.  Rainfall forecast has diminished for the
next few days allowing some of these flood waters to work their way
into the Gulf.  No additional significant flooding 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:
http://water.weather.gov/ahps/

The Flood Potential Outlook can be viewed on our webpage at:
http://www.srh.noaa.gov/wgrfc/?n=wgrfcfop

The West Gulf River Forecast Center is now on Facebook:
http://www.facebook.com/US.NationalWeatherService.WGRFC.gov

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

The forecast rainfall amounts (QPF) can be viewed on our webpage at:
http://www.srh.noaa.gov/wgrfc/?n=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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