Hydrometeorological Discussion
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AGUS74 KFWR 231647
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1147 AM CDT WED AUG 23 2017

                  VALID AUGUST 23 THROUGH AUGUST 28

...RAINFALL ANTICIPATED WITH THE PASSAGE OF COLD FRONT NEXT TWO
DAYS, TROPICAL SYSTEM HARVEY LOOMS FOR THIS WEEKEND...

                   ...METEOROLOGICAL DISCUSSION...
A ridge of high pressure is re-developing over southwest New Mexico
this morning.  This ridge brought hot and mostly dry conditions to a
fair amount of the WGRFC region the past few days. Along the western
edge of the ridge, rainfall has been observed across parts of New
Mexico, southern Colorado and far southwest Texas. With the
retrogression of the ridge, a cold front has moved out of Oklahoma
into north Texas.  Showers and thunderstorms have occurred with the
passage of this front the past 24 hours.  The heaviest rainfall the
past 24 hours was along the Red River where the area near Gordonville
received over 3 inches, while over northwest Texas near Muleshoe they
got over 2.50 inches. The rainfall is ongoing in northern Texas and
portions of west Texas, and this is expected to continue and move
slowly southward as the front moves through a moist atmosphere
across central Texas.  This rain area should diminish over central
Texas on Thursday.  Meanwhile, southeastern Texas, especially near
the coast, should be active again today and the next two days with
scattered showers and thunderstorms due to the sea breeze front.
Widespread heavy amounts are not expected.  Also, the west should
remain in an active monsoon pattern during the week, but the threat
for heavy rainfall should be reduced due to the proximity of the
ridge.

The remnants of tropical storm Harvey have once again formed into
a tropical depression this morning over the southern Gulf of Mexico.
This system is forecast to move to the northwest.  There is a high
likelihood this storm will reach tropical storm strength later today
or Thursday as it moves into the northwestern Gulf.  This storm is
forecast to then move northward, with current models bringing the
storm to the middle Texas Gulf coast later Friday.  What happens
to Harvey thereafter is problematic.  Many of the models keep the
storm moving slowly north, then stall it out due to weak steering
currents.  Then the storm is forecast to meander around south central
and southeast Texas by Monday morning and beyond. There is still
uncertainty concerning the track, speed and intensity of Harvey.
But there will be the potential of substantial rain of 10 to 15
inches with isolated amounts of over 20 inches from south central
into east central and southeast Texas and western Louisiana from this
storm.

                    ...PRECIPITATION FORECAST...
For Today into Thursday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 to 0.50 of an inch are forecast for north Texas from
roughly Midland east through Waco and Longview and into northern
Louisiana.  MAP amounts of 0.25 to 0.50 inch are also forecast for
eastern and southern New Mexico and far southwest Texas.  MAP amounts
of less than 0.25 of an inch are forecast across most of New Mexico
and Colorado, the northern half of Texas, southeast Texas and
Louisiana.

For Thursday into Friday morning, MAP amounts of 0.25 to 0.50 inch
are forecast across the eastern half of New Mexico, southern
Colorado, central into northwestern Texas, along the Texas Gulf coast
and southern Louisiana.  MAP amounts of less than 0.25 of an inch are
forecast over the remainder of the WGRFC area.

For Friday into Saturday morning, MAP amounts of 0.25 inch or more
are forecast for west Texas and the panhandle into western Oklahoma,
as well as over the southeast third of Texas and southern Louisiana.
The heaviest amounts of 7 inches are noted in southeast Texas along
the middle Texas Gulf coast near and just east of Port O`Connor. MAP
amounts of less than 0.25 of an inch are forecast across eastern New
Mexico, most of Texas and Louisiana.

For Saturday into Monday morning, MAP amounts of 0.25 inch or more
are forecast for southern and northeast New Mexico, south central
Colorado, the northeast half of Texas, and Louisiana.  The heaviest
amounts of 6 inches are noted in southeast Texas from east of Austin
through Houston to north of Beaumont TX.  MAP amounts of less than
0.25 of an inch are forecast across most of New Mexico, Colorado,
and Texas.

The latest U.S. Drought Monitor for Texas shows the area considered
to be abnormally dry is around 10%, and only 1% of Texas is
experiencing moderate drought conditions.  In New Mexico, only 1% of
the state is experiencing abnormally dry conditions, and that is in
the southwest portion. The rainfall forecast the next five days will
produce significant runoff across the southeast third of Texas and
southwest Louisiana.  Otherwise, there may be some minor runoff by
the weekend just about anywhere across Texas and perhaps across
southern New Mexico as well.

                     ...HYDROLOGIC DISCUSSION...
...Rio Grande Basin...
...Minor Flooding...
Luis Leon reservoir in Mexico is releasing water which will keep the
Rio Grande higher than normal through the Presidio and Big Bend
regions.  Current release is near 8300 cfs pushing the International
Bridge at Presidio (PRST2) into minor flood levels.  Other locations
from Candelaria downstream through Boquillas are experiencing higher
flows above action stage.

...Remainder of WGRFC Basins...
All other mainstem sites and tributaries are at seasonal flow levels
with no additional flooding expected for the next few days.  Tropical
cyclone Harvey will be closely watched by the WGRFC staff for
potential impacts along the Gulf Coast and points inland.  While no
particular area aside from the Rio Grande is sensitive, heavy
tropical rainfall can produce significant flooding where it develops.
WGRFC will be closely monitoring this situation over the next week
to determine the flooding potential from this storm.

              ...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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