Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 301621
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1120 AM CDT TUE AUG 30 2016

                 VALID AUGUST 30 THROUGH SEPTEMBER 4

...PRECIPITATION WILL CONTINUE ALONG THE SOUTHEAST TEXAS COAST AND
OVER NEW MEXICO, BUT WILL DECREASE BY THE WEEKEND...

                  ...METEOROLOGICAL DISCUSSION...

An area of low pressure has been moving very slowly southwest just
off the southeast Texas coast the past 24 hours.  Showers and
thunderstorms occurred north and east of this low over much of Texas.
The heaviest rainfall amount of nearly 6 inches occurred near Port
Aransas.  The thundershowers are expected to continue along and near
the middle and lower Texas coast today.  As the low shifts southwest
Wednesday the heavier showers will shift to deep south Texas. Since
the heaviest rains have been focused along the immediate shoreline
and over the coastal waters the last day or so, this activity has not
caused any significant mainstem river flood issues, although the
flash flood potential continues at this time.  Rainfall amounts of
3-5 inches are possible along the middle Texas Gulf coastal areas
mainly today.

Meanwhile, over the western portions of the WGRFC area, a persistent
upper level low pressure system is located over southeast New
Mexico.  Showers and thunderstorms have been occurring near and
just east of this low and has produced some locally heavy rainfall
from southeast New Mexico into west Texas.  The area in and around
Denver City TX has had 3.50 to over 4.00 inches of rain the past 24
hours.  This upper low is forecast to decrease Wednesday across
southern New Mexico, thus the potential for heavier rainfall will
begin to subside.  Some rainfall will persist over southern New
Mexico, however, until at least Thursday.

Rain chances will remain in the forecast for most of the WGRFC region
through the rest of this week as an upper level system pushes a "back
door" cold front into north Texas later Thursday.  This may produce
some showers and thunderstorms, with the heaviest rain forecast along
the Red River, into Friday.  Thereafter, a ridge of high pressure
is forecast to build back over the region and will deliver drier
conditions to most of the WGRFC area this weekend.

...Tropical updates...
Tropical Depression #9 continues over the southeast Gulf of Mexico.
Some additional strengthening is possible as it continues to move
over the Gulf of Mexico the next few days and eventually towards the
northern Florida coast about Thursday or Friday.  At this time, this
system has a low chance of impacting any portion of Texas.  We will
continue to monitor the forecast models the rest of the week and
update accordingly.

                    ...PRECIPITATION FORECAST...
For Today into Wednesday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 of an inch or more are forecast over the northwest
quarter of Texas into eastern New Mexico and southern Colorado, as
well as over the southern third of Texas.  The heaviest rain, with
MAP amounts of 1.50 inches, are forecast over extreme southeast New
Mexico.  MAP amounts of 1.00 inch are also forecast for the middle
Texas Gulf coast from Corpus Christi to Port O`Connor.  MAP amounts
of less than 0.25 of an inch are forecast over the southwest two
thirds of Texas and most of New Mexico and Colorado.

For Wednesday into Thursday morning, MAP amounts of 0.25 to 0.50 inch
are forecast for portions of southern and eastern New Mexico into
northwest Texas and the panhandle.  MAP amounts of 0.25 to 0.50 inch
are also forecast for deep south Texas.  MAP amounts of less than
0.25 of an inch are forecast over the western two thirds of Texas and
most of New Mexico and Colorado.

For Thursday into Friday morning, MAP amounts of 0.25 to 0.50 inch
are forecast for the southern half of New Mexico into west Texas, the
Texas Panhandle and extreme north Texas.  MAP amounts of less than
0.25 of an inch are forecast over the northwestern two thirds of
Texas, northwest Louisiana, and most of New Mexico and Colorado.

For Friday into Sunday morning, MAP amounts of 0.25 inch are forecast
for extreme New Mexico and portions of central Texas.  MAP amounts of
less than 0.25 of an inch are forecast over most of Texas, and most
of New Mexico and Colorado.

After the widespread rain the past week or two over parts of New
Mexico and Texas, drought conditions have eased somewhat. The U.S.
Drought Monitor has categorized Texas as 29% abnormally dry, with
less than 1% in severe drought. Over New Mexico, 88% of the state is
abnormally dry, and 24% remains in the moderate drought category.
The showers and thunderstorms forecast the rest of this week into
the weekend will keep more serious drought conditions from developing
over the WGRFC region, while many sections continue drought-free.
Since topsoil has become moister, some runoff is possible where the
heaviest rain is forecast. However, since the heaviest rain is
forecast where soils are drier most of the runoff that results will
be insignificant across the majority of the WGRFC area.

                     ...HYDROLOGIC DISCUSSION...
...Rio Grande Basin...
...Minor Flooding...
Locally heavy rainfall occurred over the last 24 hours along the Rio
Grande River Basin near Presidio, Texas and Ojinaga, Mexico.  Minor
rises occurred along the Rio Grande and Rio Conchos Rivers in this
vicinity.  Upstream, minor flooding is occurring near Candelaria due
to recent rainfall.  River levels at all of these locations have
crested and are now falling.

...Nueces Basin...
...Higher Flow Non-Flood Forecasts...
Runoff from rain that fell last week continues to flow down the
mainstem of the Nueces River. No flooding is expected at this time,
but higher than normal flow will continue through the area over the
next few days.

...Remainder of WGRFC Basins...
All other rivers are recovering from recent rainfall.  Many locations
are still well above normal flow for this time of year.  With
additional rainfall expected over the next few days, new minor
rises are expected in many of our river systems, especially the Big
Bend region of the Rio Grande.

              ...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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