Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 201620
HMDFWR
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1120 AM CDT MON APR 20 2015

                   VALID APRIL 20 THROUGH APRIL 25

...SOME MORE RAINFALL IS EXPECTED OVER MOST OF THE WGRFC AREA THE NEXT
FIVE DAYS, BUT NONE OF IT IS EXPECTED TO BE EXCESSIVE...

                  ...METEOROLOGICAL DISCUSSION...
A large low pressure system moved from western Kansas eastward
through Missouri the past 24 hours.  With the passage of this low, a
cold front swept across Texas. Showers and thunderstorms developed
along and ahead of this front Sunday afternoon and evening over
southeast Texas and Louisiana.  Also, rain and high elevation snow was
reported over portions of southern Colorado and northern New Mexico.
The heaviest rainfall the past 24 hours was in the Houston area with
around 1.00 to 1.50 inches observed.

This morning a ridge of high pressure system has formed over western
Oregon. This has put the northern parts of the WGRFC area in a
northwesterly upper air flow. While no major storms are forecast to
move through this flow, a minor storm may produce light precipitation
over northern New Mexico and southern Colorado.  Over the south, an
upper air disturbance will move eastward from Mexico and will move
across south Texas today into Tuesday morning.  This disturbance is
interacting with the cold front to bring some rain to south Texas,
especially the lower Rio Grande valley. At this point, heavy rainfall
is not expected during this period. Elsewhere over the WGRFC area,
dry weather is expected into Tuesday morning.

On Tuesday a new low pressure system is forecast to develop off the
California coast, and by Wednesday the low will be over southern
California.  This will again put the WGRFC region in a southwesterly
upper air flow, which will increase the atmospheric moisture.  As the
moisture increases late Tuesday and Wednesday, some showers and
isolated thunderstorms are forecast to develop across a good part
of Texas. At this point extreme northern Texas and Oklahoma is the
most likely location for heavier rainfall.

On Thursday the California low will finally begin to move eastward.
As this occurs there will likely be a few periods of showers and
thunderstorms late Thursday into Friday over Texas.  Again, it does
not appear that heavy rainfall will fall. By Friday night the low
pressure system will be weaken as it moves over Kansas, with dry air
moving into Texas from the west.  This will cause the rainfall to
diminish Friday night and Saturday morning over most of the area
except for deep south Texas.

                    ...PRECIPITATION FORECAST...
For Today into Tuesday morning, Mean Areal Precipitation (MAP) amounts
of 0.25 to 0.50 inch are forecast for deep south Texas.  The heaviest
rain will be south of McAllen and Brownsville TX over northeast
Mexico. Lighter amounts of MAP are forecast for the southern quarter
of Texas, a good part of Colorado, the northeast quarter of New
Mexico, and the northern Texas panhandle.

For Tuesday into Wednesday morning, MAP amounts of 0.25 inch are
forecast for parts of north central Texas near and northwest of the
DFW metroplex.  MAP amounts of 0.25 of an inch are also forecast over
northeast Mexico.  Lighter amounts of MAP are forecast for much of the
WGRFC region...except for western Louisiana, far west Texas and the
southern two thirds of New Mexico.

For Wednesday into Thursday morning, MAP amounts of 0.25 inch or more
are forecast for a good part of northern and central Texas into
southern Oklahoma.  The heaviest rain, with MAP amounts of 1.00 inch,
are forecast north of the WGRFC area over southern Oklahoma.  Lighter
amounts of MAP are forecast for much of the WGRFC region...except for
far west Texas and the southern three quarters of New Mexico.

For Thursday into Saturday morning, MAP amounts of 0.25 inch or more
are forecast for roughly the eastern two thirds of Texas into most of
Louisiana. MAP amounts of 0.25 of an inch are also forecast across
southern Colorado. The heaviest rain, with MAP amounts of 1.00 inch,
are forecast northeast of the WGRFC area over southwest Arkansas and
northwest Louisiana.  Lighter amounts of MAP are forecast for much of
the WGRFC region...except for far west Texas and the northwest third
of New Mexico.

Moderate or worse drought conditions continue across parts of New
Mexico and Texas. In Texas, about a third of the state is experiencing
moderate or worse drought (35%), and about 15% has extreme to
exceptional drought conditions. In New Mexico, about two thirds of the
state is experiencing moderate or worse drought (62%). Lake levels in
the extreme drought areas of Texas are at or near historical lows for
this time of year. Recent precipitation events have brought drought
relief to parts of far west Texas, deep south Texas and roughly the
southeast third of the state. The rainfall expected over the next five
days over the WGRFC area could produce some minor runoff over north
Texas where the heaviest rainfall is forecast. However, no significant
runoff is expected over the majority of the WGRFC area.

                     ...HYDROLOGIC DISCUSSION...
...San Bernard Basin...
...Moderate Flooding...
It appears that the initial flood wave has crested at all sites along
the San Bernard and the recession has begun.  East Bernard is
receding a little faster than expected while Boling is seeing a
little more flow route through than forecast.  Sweeney has
appeared to have crested below major flood.  Moderate flooding
should continue for at least the next couple of days.

...Guadalupe Basin...
...Moderate Flooding...
The flooding along the Guadalupe is making its way downstream as
Sandies Creek at Westhoff has crested and dropped below moderate
flood criteria.  Victoria should have a minor bump before a full
recession and Bloomington will remain in moderate flood for the
next few days as the flood wave pushes through.

...Lavaca-Navidad Basin...
...Minor Flooding...
The Navidad River near Edna (EDNT2) has crested and will remain at
minor flood levels for a few more days but is in recession.  The
Navidad River at Strane Park near Edna (LSNT2) and the Tres Palacios
River near Midfield (MTPT2) reached moderate flood stage but have
both crested and are falling.

...Neches Basin...
...Minor Flooding...
The widespread minor flooding looks to be nearing crests at most of
the major initial flooding points and headwaters.  Routed water will
continue to be worked through causing crests to still occur at
Diboll and Lufkin.  The recessions will be long at almost all sites
so minor flooding to continue through the forecast period.

...Sabine Basin...
...Minor Flooding...
While it was not a completely dry day for the Sabine River basin,
none of the rainfall impacted any of the ongoing flooding or create
new areas of concern.  Mineola will make a brief return to flood
stage due to routed water from upper basins and Deweyville to remain
in flood but will drop in the forecast period below flood stage.

...San Jacinto Basin...
...Higher Flow Non-Flood Forecasts...
The West Fork at San  Jacinto  (HMMT2) will remain around action
stage as backwater effect from Lake Houston should keep the flow
near action stage for a few days.

...Brazos Basin...
...Higher Flow Non-Flood Forecasts...
Davidson Creek near Lyons (LYNT2) remains above bankfull.  Navasota
River near Normangee (NGET2) has crested but as runoff continues it
will remain above bankfull into next week.   The Brazos at Richmond
(RMOT2) has risen above bankfull and is expected to remain high for
a few days.

...San Antonio Basin...
...Higher Flow Non-Flood Forecasts...
The San Antonio River at Goliad (GLIT2) has crested above action
stage slightly below minor flood levels and is in recession now.

...Nueces Basin...
...Higher Flow Non-Flood Forecasts...
Local heavy rainfall near the Gulf Coast caused the Aransas River
near Skidmore (SKMT2) rose into moderate flood levels with a crest
near 14 feet and is now below bankfull levels. Runoff is also
causing the Mission River at Refugio (REFT2) to rise slightly above
action stage now but is near crest at 21.6 feet.

...Remainder of WGRFC Basins...
The rest of basins in the area are fairly dry, missing out on much
of the recent beneficial rainfall over the past week.  No
significant flooding is expected outside of the areas with ongoing
flooding.

              ...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

STORY

$$




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