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...METEOROLOGICAL DISCUSSION...

ISSUED: 1125 AM CDT WED MAY 20 2015
VALID: MAY 20 THROUGH MAY 25
Day 1 Surface Map Jump To Hydro Section Jump To Hydro Section
Day 2 Surface Map

Day 3 Surface Map

...NO END IN SIGHT TO THE STORM SYSTEMS WHICH COULD BRING PARTS OF THE WGRFC AREA LOCALLY HEAVY RAIN THE NEXT FIVE DAYS...

Southwesterly flow aloft is expected to continue the rest of the week and through the weekend. Additional upper level disturbances are expected to move through this flow and keep showers and thunderstorms, with locally heavy rainfall, in the forecast for at least some parts of Texas, extreme eastern New Mexico and western Louisiana for the entire five day forecast period. In general, this additional rainfall (with total amounts in excess of 6.00 inches, particularly in northern and central Texas) will likely cause additional moderate or greater flooding across many of our river systems. The soils are moist over much of Texas now, so any new rainfall will quickly run off. We will continue to monitor the situation over the coming days and update accordingly.

A significant upper level low pressure system moved from eastern Nevada to South Dakota the past 24 hours. As this occurred, associated upper air disturbances moved across Texas. As one disturbance passed, a cluster of showers and thunderstorms developed over the Texas panhandle which moved east across southern Oklahoma and extreme north Texas. Locally heavy rainfall occurred over some locations, with 3.50 to 7.00 inches of rain noted from near Decatur TX to near Seymour TX and northward into Oklahoma. Showers and thunderstorms recently dissipated northwest of the DFW metroplex, but new thunderstorms are developing over extreme east Texas and western Louisiana.

The disturbance which brought last nights` rain will move out of our region this afternoon, and the rainfall will temporarily decrease. But later this evening and into Thursday more upper air disturbances are forecast to move out of Mexico into Texas as a new upper low moves close to California. One disturbance will produce showers and thunderstorms over much of southwestern Texas from tonight into early Thursday morning, then the rain will spread northward to cover eastern New Mexico and all of west Texas through Thursday evening. Then on Thursday night into Friday the upper disturbance will move eastward from west Texas and bring the chances for more showers and thunderstorms further east to much of Texas. This rain may move east of the region, or temporarily weaken, by Saturday morning.

The main upper level low pressure system is forecast to move over Utah on Saturday. The next upper air disturbance ahead of this low is forecast to produce showers and thunderstorms over west Texas later on Saturday, which will move toward central and north Texas on Sunday. The rainfall should shift eastward into east Texas and western Louisiana by Monday morning. Locally heavy rainfall is possible over much of northern and central Texas this weekend.



...PRECIPITATION FORECAST...

Day 1: 24-Hour Rainfall Total Day 2: 24-Hour Rainfall Total

For Today into Thursday morning, Mean Areal Precipitation (MAP) amounts of 0.25 of an inch or more are forecast from southwest and central Texas into northeast Texas and northwest Louisiana. The heaviest rain, with MAP amounts of 1.50 inches, are forecast from north of Tyler to Texarkana. MAP amounts of 1.00 inch are forecast just southwest of Del Rio TX over northern Mexico. Lighter amounts of MAP are forecast for much of the remaining areas of the WGRFC area of responsibility except for western New Mexico.

For Thursday into Friday morning, MAP amounts of 0.25 of an inch or more are forecast for the western two thirds of Texas, the northeastern two thirds of New Mexico and much of Colorado. The heaviest rain, with MAP amounts of 1.50 inches, are forecast just northwest of Midland TX. Lighter amounts of MAP are forecast for much of the remaining areas of the WGRFC area of responsibility except for southwestern New Mexico.

Day 3: 24-Hour Rainfall Total Day 4-5: 48-Hour Rainfall Total

For Friday into Saturday morning, MAP amounts of 0.25 of an inch or more are forecast for the northwestern two thirds of Texas (except for the far west) and eastern New Mexico. The heaviest rain, with MAP amounts of 0.50 inch, are forecast over much of northern and western Texas. Lighter amounts of MAP are forecast for much of the remaining areas of the WGRFC area of responsibility except for southwestern New Mexico.

For Saturday into Monday morning, MAP amounts of 0.25 of an inch or more are forecast for most of Texas, western Louisiana, extreme eastern New Mexico, extreme northern New Mexico and southern Colorado. The heaviest rain, with MAP amounts of 4.00 inches, are forecast just east of Gainesville TX. MAP amounts of 3.00 inches are forecast over north central Texas and near San Antonio TX. Lighter amounts of MAP are forecast for much of the remaining areas of the WGRFC area of responsibility except for southwestern New Mexico.

5 Day Total Rainfall Forecast

Drought conditions continue to improve across most of the WGRFC area. Recent precipitation events have brought drought relief to many parts of Texas. In Texas, only about one quarter of the state is experiencing moderate or worse drought (23%), and only about 2% has extreme to exceptional drought conditions. Further improvement is likely with the next issuance of the drought monitor later this week. In New Mexico, a little over half of the state is experiencing moderate or worse drought (55%), but they are free from extreme or exceptional drought conditions. Many of the lakes in the extreme drought areas of Texas have levels which have begun to rise due to recent rainfall, and the lakes not in a drought category have responded and are quite full. The rainfall expected over the next five days over especially northern and central Texas will be heavy enough to produce significant runoff, and minor runoff is expected over extreme eastern New Mexico and west Texas. Elsewhere over the WGRFC area no significant runoff is anticipated.





...HYDROLOGIC DISCUSSION...

Current - Hydrology Of The Day
Current - Status Map

...Nueces Basin...
...Major Flooding...
Major significant flooding continues to occur along the Nueces River. The Nueces River at Asherton has crested at 29 feet and will slowly begin to recede over the next day or so provided no further rainfall occurs. Cotulla downstream is expected to rise due to the routed flow from Asherton close to major flood stage in a few days. This water will not cause Tilden to rise much further, but will not flow below minor flood stage through the forecast period. Atascosa River is finally receding as it drops below moderate into minor flood stage. Three Rivers has crested at 38 feet and will slowly recede, and should drop below major category later today. Lake Corpus will keep Nueces river at Mathis above major flood stage for the forecast period. Nueces River at Bluntzer has been pushed into major flooding from the releases from Corpus Christi for the period as well. Calallen will follow suit to reach the moderate flood criteria later in the week.

...Guadalupe Basin...
...Moderate Flooding...
A Flood Wave continues to move downstream that crested on both Sandies creek and Gonzales, which should push Cuero further up into minor flood stage. This should move down to Victoria later this weekend in moderate flood, and continue to keep Bloomington in moderate throughout the forecast period.

...Lavaca-Navidad Basin...
...Moderate Flooding...
The Navidad River at Sublime (SBMT2) continues to fall and has now fallen below criteria levels. Minor flood levels are forecast at Speaks (SPAT2) and Morales (MRAT2) on the Navidad River. Downstream, the Navidad River at Strane Park near Edna (LSNT2) is forecast to rise to moderate flood levels.

...San Jacinto Basin...
...Moderate Flooding...
The West Fork San Jacinto near Porter (PTET2) is continues in moderate flood level and continues to fall.

...Trinity Basin...
...Moderate Flooding...
Ongoing widespread, heavy rainfall across the entire Trinity River drainage has caused widespread bankfull, minor, and moderate flood flow conditions. Heavy rainfall overnight has caused a quick rise on the West Fork Trinity River near Jacksboro (JAKT2) where levels have already risen 15 feet over the past 12 hours. The Elm Fork Trinity River at Gainesville (GLLT2) also rose 17 feet over the past 12 hours and is currently on the recession. The Clear creek near Sanger jumped up 16 feet overnight and is nearing its crest. With Lake Livingston full, inflows are being passed, which continue to increase flows downstream through Moss Bluff creating minor to moderate flood conditions. Most basin reservoirs are full; those without flood storage are passing inflows, while flood control reservoirs continue to store and evacuate water according to regulation plans based on downstream flow control values. Collectively, these releases will keep higher than normal flows within the system mainstem for several weeks to come.

...Neches Basin...
...Moderate Flooding...
The Neches River system remains in elevated flow levels with several locations currently in flood. The Neches River near Alto (ATOT2) is cresting at moderate levels. Multiple other sites will remain in their minor to action stages with the recent rainfalls adding to the already elevated flows. Many mainstem forecast points are expected to remain in minor flood levels for at least the next week.

...Brazos Basin...
...Minor Flooding...
Several sites along the lower Brazos remain in flood. Middle Yegua creek and the Navasota River are also in minor flood due to recent local rainfall, and as all that water flows downstream will cause slow slight rises at Richmond, Rosharon, and West Columbia.

...Sabine Basin...
...Minor Flooding...
Minor flooding continues to occur in the Sabine River basin. The Sabine River at Logansport (LPTL1) has crested above flood stage due to backwater from Toledo Bend Reservoir and continues to recede. The Sabine River near Bon Wier (BWRT2) and Deweyville (DWYT2) are on the rise due to releases from Toledo Bend. Both locations are expecting crests in minor flood levels.

...San Antonio Basin...
...Minor Flooding...
The water has mostly pushed out of the area as the downstream point of Goliad continues to recede but remains in minor flood for the next couple of days.

...San Bernard Basin...
...Minor Flooding...
The San Bernard near East Bernard (EBBT2) is expected to rise above flood stage later today.

...Colorado Basin...
...Higher Flow Non-Flood Forecasts...
Only two forecasts remain as water works its way downstream with the Colorado River at Wharton cresting now in action stage, and further downstream Bay City to crest in action stage late tonight.

...Remainder of WGRFC Basins...
Currently, most rivers are have ongoing flooding conditions and remain very sensitive to further rainfall. Soil conditions remain very saturated and any further rainfall will only exacerbate the ongoing flooding.

12z-24 Hour Rainfall Accumulation Total
Excessive Rainfall Forecast

5 Day River Flood Outlook Potential
Drought Monitor


Drought Outlook

Link To Tropical Weather Link To Tropical Weather

...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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