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Hydro-Meteorological Discussion

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649 AGUS74 KFWR 291627 HMDFWR HYDROMETEOROLOGICAL DISCUSSION NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX 1126 AM CDT FRI APR 29 2016 VALID APRIL 29 THROUGH MAY 4 ...AN ACTIVE WEATHER PATTERN WILL CONTINUE INTO EARLY NEXT WEEK BEFORE A DRYING TREND BEGINS BY THE MIDDLE OF THE WEEK... ...METEOROLOGICAL DISCUSSION... A series of weather producers will continue to affect the WGRFC area through the weekend into the first part of next week. This will result in a couple rounds of showers and thunderstorms, as well as some periods of snowfall in the higher elevations of New Mexico and Colorado. The first system is located near the Four Corners region this morning. This low is bringing precipitation to New Mexico and Colorado which will eventually spread eastward. Further east, a minor upper air disturbance ahead of this low is bringing showers and thunderstorms across extreme north Texas and Oklahoma. The low near the Four Corners will move across southern Colorado today, and as this occurs the dryline will become active across central Texas. Numerous showers and thunderstorms will develop across west Texas this morning and will increase this afternoon over east Texas, including the DFW metroplex. The upper level low will lift northeast into Kansas by Saturday morning and most of the showers and thunderstorms will move east of our region. On Saturday, a cold front and dryline are forecast to move into southeast Texas and will stall. This will result in additional periods of scattered showers and thunderstorms with intermittent heavy rainfall from roughly Houston and Lake Charles into southern and central Louisiana. This system may hang around through Sunday which would bring additional rainfall to the upper Texas Gulf coast region. Meanwhile, a new low pressure system will be digging over Arizona on Sunday morning. This low will spread additional precipitation over New Mexico and Colorado, with showers and thunderstorms spreading into west Texas Sunday afternoon into Monday. The main system will begin to weaken and will shift east by Monday, with some residual rainfall expected for the southeastern half of Texas and western Louisiana Monday into Tuesday morning. Drier conditions will finally return to the region later Tuesday into Wednesday as a ridge of high pressure develops over the Rocky Mountains. ...PRECIPITATION FORECAST... For Today into Saturday morning, Mean Areal Precipitation (MAP) amounts of 0.25 of an inch or more are forecast over central and east Texas into western Louisiana, portions of southern Colorado, and extreme northeast New Mexico. The heaviest rain, with MAP amounts of 3.00 inches, are forecast for extreme east Texas and along the LA-TX-AR borders. MAP amounts of less than 0.25 of an inch are forecast over the northeast two thirds of Texas, the northern half of New Mexico and Colorado. For Saturday into Sunday morning, MAP amounts of 0.25 of an inch or more are forecast over the southeast third of Texas into Louisiana, much of southern Colorado, and northern New Mexico. The heaviest rain, with MAP amounts of 2.00 inches, are forecast for extreme southeast Texas into southwest Louisiana. MAP amounts of less than 0.25 of an inch are forecast over the southeast half of Texas, the northwestern half of New Mexico and most of Colorado. For Sunday into Monday morning, MAP amounts of 0.25 of an inch or more are forecast along and near the middle and upper Texas Gulf coast, as well as over the western quarter of Texas into much of southern Colorado and the northeastern half of New Mexico. The heaviest rain, with MAP amounts of 1.50 inches, are forecast for southwestern Texas northwest of Del Rio. MAP amounts of less than 0.25 of an inch are forecast over most of Texas and Louisiana, the northeastern three quarters of New Mexico and Colorado. For Monday into Wednesday morning, MAP amounts of 0.25 of an inch or more are forecast over the southeast half of Texas, Louisiana, as well as over a few spots over southern Colorado and northeastern New Mexico. The heaviest rain, with MAP amounts of 2.00 inches, are forecast for the upper Texas Gulf coastline. MAP amounts of 1.00 inch are forecast over southeast Texas into southern Louisiana. MAP amounts of less than 0.25 of an inch are forecast over most of the remaining portions of the WGRFC area. Soil moisture has rebounded this week as an active weather pattern continues to produce abundant rain. Soils have moistened across a good part of the state. 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 is remains in the abnormally dry category, and 44% is in moderate drought. The rainfall which is forecast over the next 5 days will produce additional runoff into the rivers over the eastern half of Texas and western Louisiana. Significant runoff should be expected over those areas with saturated soils. Elsewhere, only minor amounts of runoff are expected. ...HYDROLOGIC DISCUSSION... ...Trinity Basin... ...Moderate Flooding... A regular pattern of rainfall across the Trinity River system continues to generate higher flows and slow recessions throughout the basin. Several locations are still above minor and moderate flood levels (TDDT2), (LOLT2). The uppermost portion of the river, above Fort Worth, is still flowing well above normal with all the water supply lakes passing inflows to maintain their conservation pools. That water is keeping the mainstem of the West Fork of the Trinity well above normal all the way to Dallas, which controls the release plans for most of the flood control projects within the DFW metroplex. Until the water from upstream decreases, the DFW lakes are limited on flood pool evacuations, but are releasing as much as possible given the next rain heavy rain event expected to begin this afternoon overnight into early Saturday morning. With the forecast rainfall, minor flood conditions are possible across the upper Trinity down to Rosser and moderate flooding possible downstream along the mainstem through Liberty. ...Neches Basin... ...Minor Flooding... The latest round of forecasts for the Neches include a 24-hour QPF forcing. The most significant QPF from the 24-hour period influence falls on the middle to upper section of the basin, where up to 2 inches of QPF may materialize during the 4/30 6z period. This precipitation will produce minor rises on several of the rivers, which have not recovered from the previous weeks flooding. The precipitation is not expected to push the Neches system out of the minor category level through the weekend. ...Brazos Basin... ...Minor Flooding... Higher than normal flows continue on the lower Brazos River due to last weeks heavy rainfall. Another round of rainfall is expected today and tonight in the middle and lower Brazos River basin, which will likely cause renewed flooding on tributaries in the area. ...Sabine Basin... ...Minor Flooding... Lakes are still trying to evacuate their flood pools as more rain is set to arrive today into tonight. Rainfall will be highly localized for the heavier amounts but widespread could see 1 to 3 inches of rainfall. The rainfall is not expecting to generate significant flooding but an isolated area could see a higher amount with these convective systems. Multiple sites in the upper basin will reach minor flood which Toledo Bend will pass downstream keeping flows elevated down through Deweyville. ...San Jacinto Basin... ...Higher Flow Non-Flood Forecasts... Based on 24 hr qpf, 3 points within the San Jacinto basin are expected to climb into action stage. ...San Bernard Basin... ...Higher Flow Non-Flood Forecasts... Based on 24 hr qpf, EBBT2 is expected to climb back into action stage by tomorrow, and the recession within action stage for SWYT2 will be slowed compared to previous forecasts. ...Guadalupe Basin... All points along the Guadalupe River have fallen below criteria. ...Remainder of WGRFC Basins... Unsettled weather is in the forecast for the next 5 days and beyond. Location and amounts of rainfall will be critical in determining flood potential. Heaviest rainfall is expected Friday and into next week. ...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: The Flood Potential Outlook can be viewed on our webpage at: The West Gulf River Forecast Center is now on Facebook: National Precipitation Analysis: The forecast rainfall amounts (QPF) can be viewed on our webpage at: The US Drought Assessment: The latest on Reservoir Information for Texas: STORY $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.