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644 AGUS74 KFWR 211557 HMDFWR HYDROMETEOROLOGICAL DISCUSSION NATIONAL WEATHER SERVICE...WEST GULF RFC...FORT WORTH TX 1057 AM CDT MON APR 21 2014 VALID APRIL 21 THROUGH APRIL 26 ...A POSSIBLE LULL IN THE PRECIPITATION LATER THIS WEEK AS MORE BENEFICIAL RAINFALL IS POSSIBLE THIS WEEKEND... ...METEOROLOGICAL DISCUSSION... A weak upper level storm has been absorbed into a larger scale upper level trough of low pressure over the Mississippi Valley. Several leftover features should help increase the rain chances through Tuesday. A weak cold front/wind shift boundary over West Texas could help initiate thunderstorms. Daytime heating in areas where the cloud cover has cleared could also aid in the development of thunderstorms. Low level moisture is abundant. Precipitable Water (PW) values are running near, to slightly above normal for this time of year. Factor in the favorable upper level environment with previously mentioned upper level trough, and much of the eastern half of Texas should see needed precipitation. An upper level ridge will move over the WGRFC area by mid week. This should help keep a lid on widespread showers and thunderstorms. However, isolated activity is possible across the Texas coast. This pattern will be short lived. A quick moving Pacific storm will move into the Pacific Northwest Wednesday, crossing the Northern Plains by Thursday. This feature will drag a trough of low pressure over the area. This pattern on Thursday will look similar to the pattern over the last few days. Expected scattered showers and thunderstorms to form Thursday. Widespread heavy, significant rainfall is not expected. Even though it is beyond the scope of this forecast, there is the chance of widespread significant rainfall for the WGRFC area starting later this weekend. The more reliable meteorological models have consistently advertised a strong, well-organized Pacific storm moving across the California Coast and cross the Desert Southwest this weekend. These models have consistently showed a favorable environment for the development of heavy rainfall over the eastern 2/3 of the WGRFC area starting Sunday, and staying in the forecast through the end of their model runs. There are way too many variables in play to pinpoint where, or if, significant rainfall is likely to occur. However, if the models continue to advertise heavy rain in the same areas for the same time period, much like the last few days of model runs, the confidence for a heavy rain event will increase. We will continue to monitor this possible event and will update accordingly. ...PRECIPITATION FORECAST... For Today into Tuesday morning, Mean Areal Precipitation (MAP) amounts of 0.25 to 0.50 inch are forecast from Northeast Texas south and west into Central Texas. Lighter MAP amounts are forecast for Central New Mexico, Southern Colorado, and for most of the eastern half of Texas. For Tuesday into Wednesday morning, MAP amounts of 0.25 inch or less are forecast for Southeast Texas and for Southern Colorado. For Wednesday into Thursday morning, MAP amounts of 0.25 inch or less are foreast for the central third of Texas and for Southern Colorado. For Thursday into Saturday morning, MAP amounts of 0.25 inch or less are forecast for most of Texas and for Southern Colorado. The drought conditions have been deteriorating over the last several weeks over most of the region. Almost all of New Mexico and 82% of Texas remain in some level of drought category. In addition, 29% of Texas and 25% of New Mexico are in extreme drought. Statewide, in Texas, reservoirs are, on average, less than 65% full. This is below average for this time of year, with average being about 80% full. There is considerable variability across the state, with many of the reservoirs in the western half of the state below 50% full. Due to the dry soil moisture conditions, the rainfall which is forecast the next 5 days will not be heavy enough to produce significant runoff. Mainstem river flooding is not expected. ...HYDROLOGIC DISCUSSION... ...Rio Grande Basin... ...Higher Flow Non-Flood Forecasts... Amistad releases are elevating flows along the mainstem from Amistad downstream to Falcon Lake. No significant impacts are expected, although the river at Columbia Bridge (CBBT2) is fluctuating above an action level for pumps and livestock in the area. The duration of Amistad releases is unknown at this time. ...Remainder of WGRFC Basins... No significant flooding is expected from rainfall forecast in the next 5 days. ...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 WALLER $$