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982 AGUS74 KFWR 241656 HMDFWR HYDROMETEOROLOGICAL DISCUSSION NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX 1055 AM CST TUE NOV 24 2015 VALID NOVEMBER 24 THROUGH NOVEMBER 29 ...SIGNIFICANT RAINFALL IS EXPECTED LATE THURSDAY THROUGH SUNDAY.... ...METEOROLOGICAL DISCUSSION... An area of high pressure at the surface in the southeastern United States and dry westerly flow aloft will continue to dominate most of the region the next couple of days. As a result, cool and mostly dry conditions will persist through Thursday evening. Southerly flow at the surface in Texas is increasing low level surface moisture, which may result in light showers over Texas, particularly on Wednesday and Thursday. A strong upper level low has now developed off the Oregon coast. This is forecast to slowly move towards the southeast and reach Nevada and Utah early Thursday, and then remain over that general area through Monday of next week. Based on this pattern, abundant moisture flow will likely develop and persist over most of the WGRFC area for several days. By late Thursday, a strong cold front is expected enter North Texas and then move slowly across the state on Friday. This cold front, abundant surface moisture, and a favorable upper level pattern will lead to locally heavy rain beginning late Thursday and continuing through the weekend. In addition, the weather models are also forecasting a Pacific Tropical Disturbance moving up into Mexico on late Friday/early Saturday. This system could cause some additional moisture to interact with the upper level storm system and enhance the heavy rainfall threat over the weekend. In general, rainfall amounts of up to 5.00 inches are expected for areas along and north of I-20 over the late Thursday through Sunday period, with higher amounts closer to the Red River area. We will continue to monitor the model guidance for any changes, and will update accordingly. ...PRECIPITATION FORECAST... For Today into Wednesday morning, no significant Mean Areal Precipitation (MAP) amounts are forecast for the WGRFC area. For Wednesday into Thursday morning, no significant MAP amounts are forecast for the WGRFC area. For Thursday into Friday morning, MAP amounts of 1 to 3 inches are forecast for portions of north central and northeastern Texas. MAP amounts of 0.25 to 1 inch are forecast for portions of southern Colorado, eastern New Mexico, and for the rest of the northwestern half of Texas. For Friday into Sunday morning, MAP amounts of 2 to 4 inches are forecast for portions of central, north central, and northeastern Texas. MAP amounts of 1 to 3 inches are forecast for the rest of central and northern Texas, and for portions of southeastern Texas, northwestern Texas, and the Trans Pecos. MAP amounts of 0.25 to 1 inch are forecast for portions of southern Colorado, eastern New Mexico, and for the rest of Texas. Topsoil moisture has increased significantly with recent rainfall events which means it will require less rainfall for runoff to occur. That, along with the vegetation becoming more dormant as the growing season comes to an end, means runoff will be quicker. Over Texas only 10% of the state is abnormally dry, while over New Mexico, 26% of the state is abnormally dry. Heavy rainfall amounts of up to 5 inches over several days from late Thursday through the weekend could lead to some potentially significant runoff because of the wet soil moisture and cold season vegetation patterns. ...HYDROLOGIC DISCUSSION... ...Trinity Basin... ...Minor Flooding... River stages continue to fall across the lower Trinity River. Liberty (LBYT2) has now fallen below minor flood level. Minor flooding is still occurring downstream at Moss Bluff (MBFT2). Lake Livingston continues to decrease their releases allowing downstream river stages to recede. ...Neches Basin... ...Minor Flooding... Higher than normal flows with minor flooding continue at various locations across the Neches River basin. River stages have crested and are falling. ...Sabine Basin... ...Minor Flooding... Recent heavy rainfall throughout the Sabine River basin has generated higher bankfull and minor flood level flows. These flows levels are now receding. Toledo Bend Reservoir will continue generating power 24 hours per day, 7 days per week at one unit of power generation. ...Brazos Basin... ...Higher Flow Non-Flood Forecasts... Higher flows are occurring on the Navasota River and lower Brazos River. River stages have crested and are slowly receding. ...Remainder of WGRFC Basins... Soil moisture remains high across many river basins in the eastern half of Texas because of recent rainfall. Additional heavy rainfall is expected near the end of this week that could cause another round of flooding in the headwaters of the Sabine, Neches and portions of the Trinity. ...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 PHILPOTT $$