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017 AGUS74 KFWR 251647 HMDFWR HYDROMETEOROLOGICAL DISCUSSION NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX 1146 AM CDT MON MAY 25 2015 VALID MAY 25 THROUGH MAY 30 ...STORM SYSTEMS WILL CONTINUE TO BRING PARTS OF THE WGRFC AREA LOCALLY HEAVY RAIN TODAY AND AGAIN AT THE END OF THE WEEK... ...METEOROLOGICAL DISCUSSION... One upper level low pressure system was located over western Minnesota this morning. As this low pulled northeastward widespread showers and thunderstorms moved across east Texas and western Louisiana, with a secondary area of thundershowers following the first from south of the DFW metroplex across east Texas. Rainfall amounts the past 24 hours were heaviest over extreme northeast Texas where over 2.00 inches were noted. The focus for new rain has shifted to southwest Texas this morning, with showers and thunderstorms forecast to spread over the remainder of Texas this afternoon and tonight. Deep moisture persists over the region, with Precipitable Water (PW) values running 150 percent of normal and higher. With a second upper air disturbance moving in and deep moisture in place, widespread showers and thunderstorms have developed over west and southwest Texas. Northern and southeastern Texas as well as southwestern Louisiana will see the heaviest precipitation now through Tuesday, with an additional 2 to 3 inches of rain expected. This upper disturbance will move northeastward rather quickly and should be out of the region by Tuesday morning. A weak ridge of high pressure is forecast to move across Texas Tuesday and Wednesday which should bring a break to the widespread heavy rainfall. By Thursday morning a new upper air disturbance is forecast to approach our region from the west. This is forecast to produce a new area of showers and thunderstorms over southeast New Mexico and far west Texas by Thursday morning. This rain will then move further northeast and cover the northwest half of Texas during the day Thursday into Friday. Some locally heavy rainfall is forecast. The first disturbance is forecast to move northeast of our region by Friday evening. Thereafter, minor upper air disturbances are forecast to cross north Texas Friday night into Saturday. Additional excessive rainfall is not forecast, but the WGRFC will continue to monitor this storm and update as needed. ...PRECIPITATION FORECAST... For Today into Tuesday morning, Mean Areal Precipitation (MAP) amounts of 0.25 of an inch or more are forecast for roughly the southeast three quarters of Texas and Louisiana. The heaviest rain, with MAP amounts of 2.00 inches, are forecast over two locations. One is over parts of north central and northeast Texas. The second area is over southeast Texas from east of San Antonio through Houston to just north of Lake Charles LA. MAP amounts of 1.00 inch are forecast over a good part of the eastern half of Texas and western Louisiana. Lighter amounts of MAP are forecast for much of the remaining areas of the WGRFC area of responsibility except for eastern and southern New Mexico and far west Texas. For Tuesday into Wednesday morning, no significant MAP amounts are forecast for the WGRFC area. Light amounts of MAP are forecast for southwest Texas near Del Rio, roughly the eastern quarter of Texas, western Louisiana, extreme northern New Mexico and Colorado. For Wednesday into Thursday morning, no significant MAP amounts are forecast for the WGRFC area. Light amounts of MAP are forecast for much of the WGRFC area of responsibility except for the central and western parts of New Mexico and deep south Texas. For Thursday into Saturday morning, MAP amounts of 0.25 of an inch or more are forecast for eastern New Mexico and the northwest half of Texas. The heaviest rain, with MAP amounts of 1.50 inches, are forecast over west Texas between Midland, Childress and Abilene. Lighter amounts of MAP are forecast for much of the remaining areas of the WGRFC area of responsibility except for southwestern New Mexico. 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 15% of the state is experiencing moderate or worse drought, and extreme to exceptional drought conditions are no longer being observed. In New Mexico, a little over a third of the state is experiencing moderate or worse drought (37%), and they also are free from extreme or exceptional drought conditions. Many of the lakes in Texas have levels which have begun to rise due to recent rainfall, and some lakes are full and are releasing water. The rainfall expected over the next five days over especially the northeastern half of Texas will be heavy enough to produce significant runoff, and minor runoff is expected over the remainder of Texas. Elsewhere over the WGRFC area no significant runoff is anticipated. ...HYDROLOGIC DISCUSSION... ...Guadalupe Basin... ...Moderate Flooding... Very heavy, short duration rainfall (6 to 12 inches) Saturday and Sunday across the headwaters caused flood" onClick="return popup(this, 'notes')">flash flooding and major river flooding through Wimberly (WMBT2) and Kyle (KYET2) along the Blanco River and Luling on the San Marcos (LLGT2). This Flood Wave has caused major damage along it`s path of the Blanco and San Marcos River mainstem. Furthermore, the remnants of it is expected to cause major flooding as it moves downstream along the San Marcos into the mainstem through Gonzales (GNLT2), Cuero (CUET2), Victoria (VICT2), and Bloomington (DUPT2) to the coastal outlet. This event comes in the wake of an earlier Flood Wave still moving further downstream; now cresting through Bloomington (DUPT2). ...Nueces Basin... ...Major Flooding... The Frio River for the most part has receded except downstream near Derby which is in moderate flood now and continues to rise. San Miguel creek in the upper portion of the basin through received 4 to 5 inches of rainfall but has still yet to begin to push the wave downstream. This leads that the wave is being attenuated greatly and could only push the forecast into minor. Will wait to see what this water does over the next day or so. On the Nueces, the forecasts continue to recede in the upper portion as Cottula has crested and the Flood Wave is forecast to arrive in about 3 days in Tilden pushing it into major flood. Lake Corpus Christi has reduced the flow again alleviating the flood even more downstream at both Bluntzer and Calallen. ...Trinity Basin... ...Major Flooding... Heavy rainfall across the entire Trinity River drainage has caused widespread bankfull, minor, and moderate flood flow conditions. Flood control reservoirs continue to store flood waters minimizing downstream flood conditions. ...San Antonio Basin... ...Minor Flooding... Moderate to Major flooding is forecast in the lower San Antonio River basin. ...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 at moderate levels. Multiple other sites will remain in their minor to action stage levels 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. It should be noted that heavy rainfall is forecast over the next 24-36 hours. This will likely cause additional flooding. Lake Steinhagen is expected to increase releases as inflows increase from upstream routed flows and forecast rainfall runoff over the next few days to keep lake levels from exceeding conservation pool. ...Sabine Basin... ...Moderate Flooding... Moderate flooding continues on the lower Sabine River Basin through Bon Wier (BWRT2) and Deweyville (DWYT2) as Toledo Bend Reservoir continues to pass large inflows. Toledo Bend reduced inflows again this morning, but is expected to increase again with expected inflow increases due to forecast rainfall runoff. ...Brazos Basin... ...Minor Flooding... Minor to moderate flow conditions are occurring on the Brazos River system. It should be noted that heavy rainfall is forecast over the next couple days. This could cause additional flooding. ...Lavaca-Navidad Basin... ...Higher Flow Non-Flood Forecasts... Higher than normal flows will continue across the Lavaca River basin. ...Colorado Basin... ...Higher Flow Non-Flood Forecasts... Higher than normal flows continue down the Colorado River below Austin. ...San Bernard Basin... ...Higher Flow Non-Flood Forecasts... Higher than normal flows will continue across the lower San Bernard river. ...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. ...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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