Hydrometeorological Discussion
Issued by NWS West Gulf RFC

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AGUS74 KFWR 231613
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HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX
1112 AM CDT SUN JUL 23 2017

                    VALID JULY 23 THROUGH JULY 28

...SLIGHTLY BETTER CHANCE FOR RAINFALL OVER TEXAS FOR A FEW DAYS,
BUT MOST WIDESPREAD RAIN WILL BE WITH MONSOONAL ACTIVITY OUT WEST...

                   ...METEOROLOGICAL DISCUSSION...
After several days with high pressure in control of the Texas
weather, a minor change has occurred in the pattern.  The ridge of
high pressure which was over north Texas and Oklahoma has temporarily
weakened.  This will result in an increased chance for rainfall over
northern and eastern Texas and western Louisiana into Monday.  It
also means there will continue to be fairly widespread rainfall over
the western portions of the WGRFC area.

Monsoonal activity in our western and southwestern forecast areas
will dominate the weather through the current forecast period.
Moisture has been abundant from northern Mexico and far southwest
Texas into New Mexico and southern Colorado the past several days.
Most of New Mexico and southern Colorado has observed afternoon
and evening showers and thunderstorms the past day or two, with even
heavier rainfall over portions of Mexico.  The thunderstorms should
continue through this week, with the areas near the mountains of New
Mexico into southern Colorado being the most favored locations.  A
ridge of high pressure is forecast to redevelop over the four corners
region by Monday, so the areal coverage and intensity of the rain may
decrease for a couple days. But overall this pattern will remain
favorable for continued monsoonal, diurnal thunderstorm activity
through the week.

Further south, rain chances will continue over the Rio Grande valley
between El Paso and the Texas Big Bend area.  Diurnal thunderstorms
are forecast to develop over northern Mexico and far southwest Texas
each afternoon due primarily to upslope flow.

Over southeast Texas, data indicates an above normal amount of
moisture is in place, and already this morning showers and
thunderstorms have developed along the Louisiana Gulf coast. This
moisture, combined with the sea breeze front and an easterly wave of
low pressure, will enhance the potential for showers and
thunderstorms this afternoon and evening over east Texas, especially
near the upper Texas Gulf coast. Some of the stronger storms could
produce locally heavy downpours. The moisture may spread northward
into Monday so the rain is forecast to continue over much of east
Texas and Louisiana.  But by Tuesday the ridge over New Mexico is
forecast to strengthen, so the areal coverage of the showers and
storms will decrease by mid-week. Nevertheless, the pattern of
scattered showers and thunderstorms along and near the Texas Gulf
coast will likely repeat itself each one of the next five days.

By Tuesday and through the week, the ridge of high pressure will
broaden out eastward into northwest Texas.  This will lead to a
decreasing chance for rain in northern and western Texas.

Rainfall amounts the past 24 hours were heaviest over the west, with
the area around Midland TX receiving 1.75 to 2.00 inches and the
region southwest of Dora NM received 1.60 inches. Over the Gulf
coast, the area west of Vinton LA also got 1.60 inches of rain.

                    ...PRECIPITATION FORECAST...
For Today into Monday morning, Mean Areal Precipitation (MAP)
amounts of 0.25 to 0.50 inch are forecast over the northern and
western portions of New Mexico and southern Colorado.  MAP amounts of
0.25 to 0.50 inch are also forecast for east Texas and western
Louisiana.  The heaviest rain, with MAP amounts of 1.00 inch, are
forecast over extreme southern Louisiana.  MAP amounts of less than
0.25 of an inch are forecast over the northern two thirds of Texas
into Louisiana, as well as over west Texas and northern Mexico into
New Mexico and southern Colorado.

For Monday into Tuesday morning, MAP amounts of 0.25 to 0.50 inch
are forecast for much of the western two thirds of New Mexico,
southwestern Colorado and the Texas panhandle.  MAP amounts of less
than 0.25 of an inch are forecast over the northeast quarter of Texas
into Louisiana, as well as over northern Mexico and far west Texas
into most of New Mexico and Colorado.

For Tuesday into Wednesday morning, MAP amounts of 0.25 to 0.50 inch
are forecast for northwestern New Mexico and southwestern Colorado.
MAP amounts of less than 0.25 of an inch are forecast over most of
New Mexico, Colorado, parts of far west Texas, and along and near the
lower Texas Gulf coast.

For Wednesday into Friday morning, MAP amounts of 0.25 to 0.50 inch
are forecast for a good part of New Mexico and southern Colorado.
The heaviest rain, with MAP amounts of 1.50 inches, are forecast over
extreme northern New Mexico into southern Colorado.  MAP amounts of
less than 0.25 of an inch are forecast over most of the remainder of
the WGRFC area except for northern and western Texas.

The latest U.S. Drought Monitor for Texas shows the area considered
to be abnormally dry is around 26%, and roughly 8% of Texas is
experiencing moderate (or worse) drought conditions. In New Mexico,
27% of the state is experiencing abnormally dry conditions, with
about 7% of the state in the moderate drought category.  Due to the
dry soil moisture conditions, the rainfall forecast will not produce
significant runoff the next five days.

                     ...HYDROLOGIC DISCUSSION...
...Rio Grande Basin...
...Higher Flow Non-Flood Forecasts...
Another round of heavy rain in Mexico near Presidio has generated a
minor flood wave that has moved past Presidio and is moving toward and
into the Big Bend National Park. No flooding is expected in the park,
but higher than normal flows can be expected. Another round of much
higher than normal flows can be expected over the next few days as
afternoon thunderstorms continue in the region.

...Remainder of WGRFC Basins...
No widespread river flooding is expected over the WGRFC area 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.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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