Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 271613
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1112 AM CDT SAT AUG 27 2016

                 VALID AUGUST 27 THROUGH SEPTEMBER 1

...HEAVY RAINS EXPECTED ALONG THE TEXAS COAST THIS WEEKEND...

                  ...METEOROLOGICAL DISCUSSION...
Showers and thunderstorms will continue to impact the
upper Texas and Louisiana coast this weekend, as an area of low
pressure slowly moves across the Gulf of Mexico. Some scattered
showers were noted on radar this morning over Southern Louisiana,
however the main activity is offshore for now. One thing to note,
there is a considerable amount of moisture flowing in from the
Gulf of Mexico, and this should continue for the next few days.
Therefore, the threat is high for very heavy rainfall, flash
flooding and minor flooding to occur over the coastal areas
this weekend. Rainfall amounts of 4-6 inches (isolated amounts
up to 8 inches) are possible along the coastal areas of Texas
and Louisiana, mainly today through Monday.

Elsewhere, the activity over the Rio Grande has temporarily
decreased, however precipitation chances are expected to
increase through the weekend. Rainfall amounts of 1-2 inches
are possible, which may result in higher than normal flows
and/or minor flooding.

By early next week, a ridge of high pressure will build back
westward once again and deliver mostly dry conditions to most
of Texas...excluding the Texas coast. Although a ridge of high
pressure is forecast to dominate the area next week, there is
still a lot of uncertainty on the development (if any) of an
area of low pressure over the Gulf of Mexico and a tropical
wave moving through the Caribbean Sea. We will continue to
monitor the forecast models over the weekend and update
accordingly.

                    ...PRECIPITATION FORECAST...
For Today into Sunday morning, Mean Areal Precipitation (MAP)
amounts of up to 1.00 inch are forecast for portions of the
upper Texas and Louisiana coasts. Lesser amounts are forecast
for portions of southern new Mexico and West Texas.

For Sunday into Monday morning, MAP amounts of up to 1.00 inch
are forecast for portions of the upper Texas and Louisiana coasts.
Lesser amounts are forecast for portions of southern new Mexico
and West Texas.

For Monday into Tuesday morning, MAP amounts of up to 1.00 inch
are forecast for portions of the upper Texas and Louisiana coasts.
Lesser amounts are forecast for portions of southern new Mexico
and West Texas.

For Tuesday into Thursday morning, MAP amounts of 0.25 to 0.50
inch are forecast for portions of the southeast Texas coast,
Deep South Texas and New Mexico.

After the widespread rain the past seven days 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 this week 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, as the weather dries out some this week most of
the runoff will be insignificant across the majority of the WGRFC
area.

                     ...HYDROLOGIC DISCUSSION...
...Guadalupe Basin...
...Moderate Flooding...
Lower end of the Guadalupe River continues to move flood waters
to the Gulf. The last point along the river with a forecast is at
Bloomington (DUPT2) which has crested but will remain above
moderate flood stage for a few more hours and above flood stage
for several more days.

...Rio Grande Basin...
...Higher Flow Non-Flood Forecasts...
Heavy localized rains earlier this week have generated several
waves of water causing a few locations to rise above criteria
levels. The first wave from the Rio Conchos has arrived in Castalon
which is cresting near flood stage today. Another wave from
Terlingua Creek has arrived at Boquillas Ranger station where the
river has crested and is falling below criteria levels this morning.
Reservoirs on the Mexican side of the river continue to slowly fill
from all the recent rainfall activity.

...Nueces Basin...
...Higher Flow Non-Flood Forecasts...
Runoff from rain that fell a few days ago continues to flow down
the mainstem of the Nueces River and the Frio River. No flooding
is expected at this time, but higher than normal flow will continue
through the area over the next few days. Additional rises likely
with precipitation returning to the region over the next few days.

...Remainder of WGRFC Basins...
Soils are back to being fairly saturated over large areas of the
WGRFC region. All other rivers are recovering from the last rain
event and many locations are still well above normal flow for this
tim eof year. With additional rainfall expected over the weekend,
new rises are expected in many of our river systems during 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.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

MCCANTS


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