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...METEOROLOGICAL DISCUSSION...

ISSUED: 1115 AM CDT MON MAY 2 2016
VALID: MAY 2 THROUGH MAY 7
Day 1 Surface Map Jump To Hydro Section Jump To Hydro Section
Day 2 Surface Map

Day 3 Surface Map

...AN ACTIVE WEATHER PATTERN WILL CONTINUE ANOTHER DAY OR TWO BEFORE A DRYING TREND BEGINS BY THE MIDDLE OF THE WEEK...

Another storm system is affecting the WGRFC area this morning, but its grip on the region will diminish by tonight. This storm is currently bringing another round of showers and thunderstorms, and earlier brought some periods of snowfall to the higher elevations of New Mexico and Colorado. ahead of this storm, showers and thunderstorms developed Sunday along the upper Texas Gulf coast into southern Louisiana along a cold front. These thunderstorms have now moved offshore over the Gulf of Mexico. Showers and thunderstorms also formed from west Texas into northern and central Texas the past 24 hours. The heaviest rain the past 24 hours occurred over southwestern Louisiana where the Lake Charles LA area received an additional 5.00 to 9.50 inches. In Texas, Woodville received 5.00 inches. This latest low pressure system moved from Arizona eastward to Oklahoma the past 24 hours. This low will continue to weaken as it shifts quickly eastward today, and an upper level trough will move across Texas. As this occurs there will be some residual showers and a few thunderstorms over the southeastern half of Texas and western Louisiana today into late tonight before ending.

A final upper air disturbance is forecast to move southeastward across Oklahoma Tuesday and across Texas Tuesday night and Wednesday morning. Aside from some light showers over the western parts of north Texas during the time of maximum heating Tuesday, little or no precipitation will occur from this disturbance.

Drier conditions will finally return to the region Wednesday through early Saturday morning as a ridge of high pressure develops over the Rocky Mountains and moves eastward over Texas.

By Saturday morning a new low pressure system will be moving from southern California to southwestern Utah. Ahead of this low, moisture is forecast to begin flowing northward. This may result in some precipitation over parts of far southwest Texas, New Mexico and Colorado by Saturday morning.



...PRECIPITATION FORECAST...

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

For Today into Tuesday morning, Mean Areal Precipitation (MAP) amounts of 0.25 of an inch or more are forecast over roughly the southeast half of Texas and most of Louisiana. The heaviest rain, with MAP amounts of 1.50 inches, are forecast for the lower Sabine River eastward into southern Louisiana. MAP amounts of less than 0.25 of an inch are forecast over the southeast two thirds of Texas and Louisiana, the northwest half of New Mexico and a good part of Colorado.

For Tuesday into Wednesday morning, no significant MAP amounts are forecast for the WGRFC area. MAP amounts of less than 0.25 of an inch are forecast over the western parts of north Texas westward into the Texas panhandle, over a good part of New Mexico and southern Colorado.

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

For Wednesday into Thursday morning, no significant MAP amounts are forecast for the WGRFC area.

For Thursday into Saturday morning, no significant MAP amounts are forecast for the WGRFC area. MAP amounts of less than 0.25 of an inch are forecast over the northeast third of New Mexico and most of Colorado, and far southwestern Texas.

5 Day Total Rainfall Forecast

Soil moisture rebounded this past week as an active weather pattern produced abundant rain. Soils are now very moist across a good part of the state, especially the eastern portions. Texas is now categorized as being 13% abnormally dry, with 2% in the moderate drought category. These dry areas are confined to the Texas panhandle and the far western portions of the state, with the remainder of the state free of drought. Over New Mexico, almost the entire state remains in the abnormally dry category, and 44% is in moderate drought. The rainfall which is forecast over the next 5 days may produce significant additional runoff into the rivers over extreme southeastern Texas and western Louisiana, as those areas have saturated soils. Elsewhere, only minor amounts of runoff are expected.

...HYDROLOGIC DISCUSSION...

Current - Hydrology Of The Day
Current - Status Map

...San Jacinto Basin...
...Major Flooding...
Additional rains have caused the East Fork San Jacinto to experience a sharp rise near New Caney (NCET2) and is expected to crest slightly above major flood levels for a brief period. Other sites are in slow recession at this time.

...Trinity Basin...
...Major Flooding...
Heavy rain fell across portions of the Trinity River basin over the past 3 days, which will cause moderate to major flooding for several areas along the river.

Both Cedar creek Reservoir and Lake Livingston are currently passing inflow from upstream runoff. These releases are generating moderate flood levels on the mainstem Trinity River at Trinidad (TDDT2) and Long Lake (LOLT2). Downstream, the Trinity River at Liberty (LBYT2) is forecast to rise into major flood levels by the middle of the week.

For the upper Trinity, water supply reservoirs are passing inflows to maintain their conservation pools. Flood control reservoirs are also evacuating their flood pools. This is keeping the mainstem of the Trinity and its tributaries well above normal.

...Sabine Basin...
...Major Flooding...
Water continues to make its way through the system from the upstream on down. The routed water will push Gladewater into major flood. Multiple other sites will remain elevated and continue to rise into moderate flood impacting local roadways and agriculture. Toledo Bend has already raised their releases today and it is still raining over the lake so more releases may be required. This will create minor flooding currently downstream of the lake.

...Neches Basin...
...Moderate Flooding...
Recent rainfall in the upper half of the Neches River Basin has pushed numerous forecast points into minor and moderate flood stage. Lakes remain full with flood storage being slowly released as it can be from Sam Rayburn Reservoir.

...Brazos Basin...
...Minor Flooding...
Higher than normal flows continue on the lower Brazos River due to recent heavy rainfall,. Navasota River at Easterly (EAST2) and near Normangee (NGET2) are the only sites in this basin that are forecast to go into minor flood from the recent rainfall.

...San Bernard Basin...
...Higher Flow Non-Flood Forecasts...
Heavy rain has slowed the recession within action stage for Sweeny (SWYT2) but should be below action stage over the next couple of days.

...Remainder of WGRFC Basins...
Soils remain wet over most of the WGRFC area, but a little break from rainfall is expected after the last of this rain event leaves the region. Next shot at significant rain will be next Monday.

For today`s remnant rain, location and amounts of rainfall will be critical in determining river response, but the heaviest rainfall is expected to remain over southeastern portions of Texas.

12z-24 Hour Rainfall Accumulation Total
Excessive Rainfall Forecast

5 Day River Flood Outlook Potential
Drought Monitor


Drought Outlook


...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

STORY

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