An update on Texas drought conditions from Jeff Lindner of the Harris County Flood Control District. ------------------------------------------------------------------------------------- Drought conditions worsen across the state! A prolonged period of dry weather has resulted in worsening drought conditions after some slight improvement in March. The current dryness continues the multi-year drought that has gripped Texas since late 2008. The January 1 to April 30th statewide average rainfall was only 2.17 inches which is 2.50 inches below normal and the start of 2014 is the 6th driest statewide rainfall recorded since 1895. San Angelo, TX has recorded only .50 of an inch of rainfall in 2014! Drought Monitor: The drought monitor as of April 29th, indicates severe to exception drought conditions across nearly all of central into NW TX and most of the panhandle. D4 conditions, or exceptional drought, has risen from 13% of the state to 18% of the state in the last week. Currently 90% of the state is in some form of drought up from 86% last week and 80% three months ago. Across SE TX moderate drought conditions are found from Lake Livingston south and westward to The Woodlands and also across southern Fort Bend, Brazoria, Wharton, and Matagorda Counties. Severe drought conditions are found over Jackson and Victoria Counties. The region roughly along I-10 from Sealy to Houston to Liberty is abnormally dry. Rainfall: Rainfall has been running below normal since late November 2013 and April 2014 was extremely dry across the region and much of the state. The coastal counties have experience rainfall of 25% of normal for the last 5 months with much of the area seeing rainfall of 30-50% of normal. To put it into perspective on how dry it has been, the current dry period is compared to the horrible drought year of (2010-2011) below for the coastal climate sites. The following compares the December 2013-April 2014 period with that of December 2010-April 2011. Galveston: 5.48 in (driest period ever recorded) 9.48 inches in 2010-2011, 11th driest on record. Note records go back to 1871 for Galveston. Freeport: 5.43 in (driest period ever recorded) 7.61 inches in 2010-2011, 7th driest on record Palacios: 3.90 in (driest period ever recorded) 6.68 inches in 2010-2011, 10th driest on record. Palacios recorded .01 of an inch of rainfall in April Houston Hobby: 7.33 in (second driest period ever recorded) 11.06 inches in 2010-2011, 11th driest on record. Hobby Airport recorded a “trace” of rainfall in April The following rainfall departures across the area from December 1, 2013 to April 30, 2014: Anahuac: -6.46 Angleton: -12.78 (total rainfall is 4.38 inches) Bay City: -9.61 Baytown: -6.58 Bellville: -6.26 Cleveland: -9.90 College Station: -9.37 Columbus: -5.95 Edna: -8.26 El Campo: -8.47 Freeport: -10.86 Galveston: -10.88 BUSH IAH: -8.02 Houston Hobby: -10.23 Huntsville: -7.39 Liberty: -7.98 Livingston: -10.66 Palacios: -10.20 Sugar Land: -8.82 Victoria: -5.77 (Jan 1 to April 30) since 10-1-13: -10.27 Only three first or second order climate locations have recorded 10.0 or greater inches of rainfall in the last 5 months and none have recorded 15.0 inches. Across North TX: Waco has recorded its 2nd driest Jan 1 to April 30 period ever with a total rainfall of only 3.39 inches. The driest Jan 1-April 30 period was in 1943 with 3.37 inches of rainfall…so the record driest still stands by only .02 of an inch. Note records go back to 1902. Dallas has recorded its 3rd driest Jan 1 to April 30 period ever with 3.93 inches of rainfall. The driest Jan 1 to April 30 was in 1909 with 2.27 inches of rainfall. Note records go back to 1899. Wildfire Conditions: KBDI values which range on a scale from 0 (saturated) to 800 (no moisture to 8 inches deep) are averaging 300-400 across much of the region. Jackson County is showing values of 500-600 with a few locations showing 600-700 in the northwest part of Jackson County. Portions of western Brazoria County and southern Montgomery County are also showing higher values than the rest of the region. Up until the last few weeks wildfire activity had been slow as enough rainfall had fallen to keep fine fuels green and moist. However recent very dry air masses and overall lack of rainfall combined with warming temperatures have resulted in a significant decline in fine fuels in the last two weeks making wildfire ignition much easier compared to previous weeks. Large fuels and canopy fuels remain in good condition, but ladder fuels are starting to show signs of drying and without significant rainfall soon ladder fuels will become increasingly dry increasing the potential for larger and hot wildland fires. 100hr fuels across much of the region are classified at critically dry while 10hr fuels are running with as little as 2%-5% moisture. Conditions are even worse across central and west TX where the potential for fast moving wind driven wildfires is extreme. Lack of rainfall in this areas has resulted in little to no spring green-up. Currently 86 TX counties have burn bans in place…all are west of I-35. In the last 7 days 67 fires have burned over 16,000 acres across TX. Water Supply and Lake Levels: The colder than average winter and spring helped to mitigate the consequences of the dryness, but that is changing now that temperatures are warming and evaporation rates increasing. Lake levels across SE TX are doing well, but are below average for the time of year. It is not good going into the warm season with lakes below conservation levels. Conditions are central, west, and north TX are much more dire. In fact several lakes in north TX fell to record low levels in April which tends to be the wetter time of year for this part of the state. The multi-year drought conditions continue to have significant impacts on lake levels and water supply. The current total state storage is 24,538,797 acre feet or 64% of normal. This is down .7% in the last month and 2% lower than this same time in 2013 which is about 473,000 acre feet lower than 2013. Lake levels east of I-35 are averaging in the 80-100% of capacity level while lakes across west TX are generally averaging 0-10% of capacity. The combined storage for rivers and storage reservoirs that drain into SE TX are listed below: Lower Brazos River Basin: 76% Upper Brazos River Basin: 47% Upper Colorado River Basin: 11% Lower Colorado River Basin: 41% Lavaca River Basin: 85% Guadalupe River Basin: 81% Upper Trinity River Basin: 67% Lower Trinity River Basin: 100% San Jacinto River Basin: 98% Nueces River Basin: 47% Lake Level Departures and (Percent of Capacity): Lake Buchanan: -30.03 (38%) Lake Conroe: -.62 (97%) Lake Houston: 0.00 (100%) EV Spence: -72.58 (2.3%) Falcon: -27.72 (33%) Lake Livingston: +.14 (100%) OC Fisher: -59.12 (0.6%) Sam Rayburn: -1.97 (92%) Lake Somerville: -2.73 (81%) Lake Texana: -3.86 (78%) Lake Travis: -55.37 (34%) Toledo Bend: -1.45 (94%) Choke Canyon: -24.41 (31%) North Texas Record Low Lake Levels: Lake Granbury: set a new record low of 682.48 on April 20. Previous record was 685.28 in Aug 1978 Lake Nocona: set a new record low of 815.62 on April 20. Previous record was 816.95 in Oct 2000. Lake Ray Hubbard: set a new record low of 427.90 on April 3. Previous record was 429.72 in Oct 2000 Highland Lakes: Inflow into the Highland Lakes (Travis and Buchanan) in March was 8,102 acre feet or only 9% of normal. Inflows from Jan 1 to March 30 were lower than in 2011 (51,275 acre feet in 2011 vs. 29,860 acre feet in 2014). The current combined storage of both Lakes Travis and Buchanan is 36%. Without significant rainfall the forecast is for a continued decline in the storage levels reaching (622-618 ft) by July 1 and (617-611 ft) by October 1 for Lake Travis. The historical low for Lake Travis is 614.18 ft established on 8-14-1951. The combined storage record low is 31% established on 9-9-1952 and based on current projections this level could be reached by the middle of this summer. Groundwater: There are 17 key groundwater aquifer locations across the state. Eight locations saw an increase in ground water in March and 9 locations saw a decrease including the Edwards Aquifer (J-17) well. The level of the Edwards Aquifer is currently .79 of a foot above stage 3 critical management level in that segment of the system. The current level is .51 of a foot lower than last month and 6.8 ft lower than this time last year. Water Restrictions: A total of 30 municipalities across the state have less than 90 days of remaining water supply and 7 have less than 45 days. The City of Wichita Falls, TX has only 25% of its conservation volume. The reservoirs that supply San Angelo, TX with water have only 8% capacity remaining. The City of Dallas current water storage is at 68% down 12% from one year ago. The City of Fort Worth water storage is at 70% down 7.8% from last year. Flows on the Guadalupe River at Victoria have been falling dangerously close to the 4.2 ft (150cfs) for the city to be able to withdrawal water. Flows have fallen to 4.6 ft (296 cfs) in the last few weeks. A total of 768 jurisdictions have mandatory water restrictions in place with an additional 389 with voluntary restrictions in place. A total of 1,157 systems are currently affect out of 4, 639 systems statewide or about 1/4th of the state’s systems are currently impacted. Agriculture: Moist has been severely lacking from S TX into the coastal bend, along the coastal plains, and into much of western and central/north TX. Spring crops had just enough moisture to germinate, but have since been hit with the very dry April. Crops are showing signs of wilting and is some locations are only about ½ of expect heights for this time of year. Stock ponds and grazing grasses are in fair to poor shape and without rainfall soon, water supplies will be depleted in June in many cattle ponds. Without widespread rainfall soon, significant crop losses will be likely. Soil moisture losses have been the greatest in and around Victoria where deficits are averaging between -80mm and -100mm Short Term Outlook: Strong upper level storm system appears to still be on track to affect the state starting as early as Thursday and lasting into the weekend. Rain chances continue to look fairly decent with this system, but the morning GFS run has backed down on amounts compared to yesterday. This looks like the best opportunity for rainfall for SE TX and much of the state in the last 2-3 months. Summer Outlook: Besides some sort of tropical system there appears little to break the expanding drought or offer significant rainfall. May and June tend to be some of the wettest months across the state as slow moving or stalled fronts interact with increasing Gulf of Mexico moisture. Temperatures are only going to warm increasing the evaporation rates and helping to dry the ground which in turn warm the air temperature even more. This cycle is very hard to break once it is established and typically in the summer months when weather patterns are weak only a tropical system is capable of interrupting such strong feedback. Far Range Outlook: There is “hope” on the horizon! A significant warming is underway across the central Pacific Ocean with deep water warm anomalies showing as much as 2-5 degrees of above average warmth in the central Pacific. It appears that ENSO warm phase (El Nino) is becoming increasing possible by the middle of this summer. While ENSO warm indices have stopped increasing in the past few weeks, the passage of a well defined Kelvin wave should help to resume the increases. Other factors such as the strongly slope thermocline under the sea surface also support continued warm of the sea surface/sub sea-surface. While this will be of little help through the summer of 2014, El Nino events tend to support a wet and cold fall/winter/spring in TX. With the onset of El Nino conditions in mid summer and possibly peaking in the fall of 2014 a transition to a wetter pattern is possible in TX post summer 2014. While El Nino usually supports above average rainfall in the state during the cold season, back ground global patterns remain in place that favor a drier than average southern plains, but this is the most promising large scale change that could affect TX since the El Nino of 2009-2010. Sources: NWS (Houston, Fort Worth, Corpus Christi), LCRA, TWDB, TFS.
Posted on: Mon, 05 May 2014 18:49:34 +0000
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