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997 AGUS74 KFWR 271732 HMDFWR HYDROMETEOROLOGICAL DISCUSSION NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX 1132 AM CST FRI NOV 27 2015 VALID NOVEMBER 27 THROUGH DECEMBER 2 ...RAINFALL, SOME OF WHICH WILL BE SIGNIFICANT, IS EXPECTED OVER A GOOD PART OF THE REGION THROUGH SUNDAY.... ...METEOROLOGICAL DISCUSSION... A major storm system continues to be present to the west of the WGRFC area. At the surface, a moist southerly flow of Gulf moisture is occurring, and aloft high level moisture is also present from the eastern Pacific Ocean. As upper disturbances in the southwest flow increased the past 24 hours, widespread rain and embedded thunderstorms developed over most of Texas, as well as over a good part of New Mexico and Colorado. Higher elevation snow occurred over the western mountains, and more snow can be expected today over the mountains of northern New Mexico and Colorado, and this snow should continue the next few days. A mixture of wintry precipitation is possible at lower elevations from eastern New Mexico through the Texas panhandle into western Oklahoma the next few days. The heaviest rain the past 24 hours was north of Dallas, with 6.50 to 7.00 inches noted near Anna and McKinney. More significant rainfall will persist over most of Texas through Sunday night. The strong upper level low pressure system is located over western Utah this morning. This low is forecast to shift westward through Saturday before moving northeastward to Wyoming by Sunday night. Southwesterly flow aloft will continue over the WGRFC area of responsibility through the weekend. Due to the persistence of this flow, additional precipitation is expected. At the surface, a strong cold front moved through north Texas early this morning and is over central Texas now. The front will move slowly the rest of today. The cold front and upper level pattern will combine to produce conditions favorable for locally heavy rainfall over much of the WGRFC area, especially over north and central Texas, along an behind the front through Monday morning. In addition, the weather models are also forecasting that eastern Pacific Hurricane Sandra will move over southwestern Mexico as a Tropical Storm early on Saturday before dissipating over land as it moves northeastward on Sunday. This system could cause some additional moisture to interact with the upper level storm system and cold front to enhance the heavy rainfall threat in Texas and western Louisiana through Sunday. In general, rainfall amounts of up to 6.00 inches are expected for areas east of I-35 and north of I-30 from today through Sunday, with the highest amounts near the Red River. Amounts of over 4.00 inches will be widespread across central and north Texas. We will continue to monitor the model guidance for any changes, and will update accordingly. Drier air from the west should shut down the prospects of significant rainfall on Monday as the upper low shifts eastward over Nebraska and Iowa. But on Tuesday a new, but weaker, upper air disturbance will approach Texas from the west. There may be some residual rainfall development from central into east Texas and Louisiana from later Tuesday into Wednesday morning as this upper disturbance crosses the WGRFC area. ...PRECIPITATION FORECAST... For Today into Saturday morning, Mean Areal Precipitation (MAP) amounts of 0.25 inch or more are forecast for southern Colorado into northern New Mexico, and from the southeastern quarter of New Mexico into most of Texas. The heaviest rain, with MAP amounts of 2 to 4 inches, are forecast from central into north central and northeastern Texas and eastern Oklahoma. MAP amounts of less than 0.25 inch are forecast for most of the rest of the WGRFC area. For Saturday into Sunday morning, MAP amounts of 0.25 inch or more are forecast for extreme southeast New Mexico into a good portion of Texas into southwest Arkansas. The heaviest rain, with MAP amounts of 2.00 inches, are forecast for most from central into northeastern Texas. MAP amounts of less than 0.25 inch are forecast for most of the rest of the WGRFC area. For Sunday into Monday morning, MAP amounts of 0.25 to 0.50 inch are forecast for central and northeast Texas into northern Louisiana. MAP amounts of less than 0.25 inch are forecast for most of the rest of Texas, western Louisiana, northeast New Mexico and southern Colorado. For Monday into Wednesday morning, MAP amounts of 0.25 inch are forecast for central and east Texas into most of Louisiana. MAP amounts of less than 0.25 inch are forecast for most of the rest of Texas and Louisiana. Topsoil moisture is very high due to recent rainfall events which means it will require less rainfall for runoff to occur. That, along with the vegetation being dormant now that the growing season has come to an end, means runoff will be quicker. Over Texas only 7% of the state is abnormally dry, while over New Mexico, 26% of the state is abnormally dry. Heavy rainfall amounts of up to 6 inches, on top of what rain has already fallen, are forecast over the next couple days through the weekend. This will lead to some new or additional significant runoff because of the wet soil moisture and cold season vegetation patterns. ...HYDROLOGIC DISCUSSION... ...Trinity Basin... ...Moderate Flooding... Overnight rains has pushed several sites back into flood levels while others are forecast to go above flood levels. The West Fork Trinity River at Grand Prairie (GPRT2) is expected to crest slightly above moderate flood levels by early Saturday. The Elm Fork Trinity River near Carrollton (CART2) is near a crest of 11 feet this morning and should fall quickly over the next 24 hours. Further downstream at Dallas (DALT2), the Trinity river is expected to crest near 40 feet late tomorrow night. Another round of heavy rains in the next 24 hours could push the Dallas reach into major flood levels. Sister Grove creek near Blue Ridge (BVWT2) is expected to crest slightly above moderate flood levels this afternoon. ...Sabine Basin... ...Moderate Flooding... Localized heavy rainfall in the upper Sabine will push Greenville and Quinlan into moderate and minor flood respectively. More rainfall is expected which could push these smaller creeks even higher over the next few days. ...Brazos Basin... ...Minor Flooding... Locally heavy rainfall has generated some rises on the Brazos River System. At this time, minor river flooding is expected around the De Leon basins of the Sabana and Leon Rivers. Higher flows should be expected as the threat for rainfall continue into next week. ...Remainder of WGRFC Basins... Heavy rainfall occurred overnight in portions of the Brazos, Trinity and the upper Sabine. Additional rainfall is expected tonight through Sunday that could cause another round of significant flooding in the headwaters of the Sabine, Neches and portions of the Trinity and Brazos over the weekend. ...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.