Jeffrey Lindner Texas Drought update 11-2-2011


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Recent rains during October have helped in some recovery across parts of the state, but even with the rainfall most areas have ended October with below average rainfall for yet another month.

The most significant development in the month of October was the falling of the PDSI to its lowest level ever for the state of Texas during the month of September surpassing the 1950’s PDSI values. In 1 year the PDSI has fallen a staggering 10 points from nearly no drought to one of the worst droughts ever in this state.

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Jeffrey Lindner Texas Drought update 11-2-2011

  1. 1. From: Lindner, Jeffrey (Flood Control)Sent: Wednesday, November 02, 2011 10:27 AMSubject: 2011 Drought UpdateHistoric drought continues…Recent rains during October have helped in some recovery across parts of the state, but even with therainfall most areas have ended October with below average rainfall for yet another month.The most significant development in the month of October was the falling of the PDSI to its lowest levelever for the state of Texas during the month of September surpassing the 1950’s PDSI values. In 1 yearthe PDSI has fallen a staggering 10 points from nearly no drought to one of the worst droughts ever inthis state.-7.97 Sept 2011-7.80 Sept 1956-7.09 Aug 1918-6.10 Jul 1925-5.51 Sept 2000Based on the above information we have effectively accomplished a similar magnitude drought in 13months that took 7 years in the 1950’s. Based on the PDSI the current drought now surpasses thedrought of the 1950’s, but is much shorter in duration. Official word on the historical magnitude of thecurrent drought will be released from the Office of the State Climatologist at Texas A&M indetermination if this is in fact going to be declared the drought of record for Texas.The current drought Monitor indicates 69.6% of the state of Texas is in D4 conditions or the worsecategory on the scale with 90% of the state in either D3 or D4 conditions. Improvements were notedacross north Texas during October where rainfall was plentiful early in the month…but it should beunderstood that a few rainfall events will not end a drought of this magnitude. It is interesting to notethat on 12-28-2010 none of the state of Texas was in D4 drought conditions and only 9.5% was in D3conditions. In the past 11 to 12 months severe to historic drought has developed in nearly every part ofthis state.To place the current drought into some perspective in Harris County. Pasadena had received 9.62 inchesof rainfall from Jan 1 to Oct 8 of this year which is just over the amount of rainfall El Paso, TX wouldreceive of 8.44 inches for this time period. Until the October 9th rainfall event much of this area wassuffering through conditions more similar to west TX than SE TX. 1
  2. 2. A review of the October 9th Rainfall Event and its comparison to 2011 rainfall totals:Location Rainfall: 1-1-11 to Rainfall 10-9- New Yearly % 2011 Yearly 10-8-11 11 Total Total on 10-9940: Lt Vince Bayou at 9.24 6.92 16.16 43%Jackson920: Vince Bayou at W 10.52 6.88 17.40 40%Ellaine320: Berry Bayou at 11.44 6.36 17.80 36%Forest Oaks310: Berry Bayou at 11.56 5.84 17.40 34%Nevada240: Armand Bayou at 9.52 5.00 14.52 34%Beltway 8610: Taylor Bayou at 12.16 5.80 17.96 32%Shoreacres620: Lt Cedar Bayou at 8th 12.0 5.64 17.64 32%St640: HCFCD F101 at Sens 10.8 4.52 15.32 30%Rd230: Big Island at 13.0 4.28 17.28 25%Fairmont270: Willow/Springs at 11.72 4.64 16.36 28%Fairmont125: Chigger Creek at 11.32 4.88 16.20 30%Windsong1070: Spring Creek at SH 10.84 3.20 14.04 23%249550: White Oak at 11.32 4.44 15.76 28%Lakeview2210: Buffalo at Turning 13.0 5.68 18.68 30%BasinAs noted by the table above sites 940 and 920 in Pasadena picked up 43% and 40% of their total rainfallthis year on the 9th in less than 12 hours. The 6.92 inches at Lt Vince Bayou in Pasadena on the 9th wasgreater than the rainfall from Feb 1-Oct 8 which totaled only 5.16 inches (so more rainfall fell in a fewhours on the 9th than the entire 8 month period prior…WOW!Rainfall departures now for the past 13 months are at or above 30 inches for most locations in SE TX andapproaching 40 inches at Tomball. 2
  3. 3. Rainfall Departures from October 1, 2010 to October 24, 2011 are:Bellville: -29.09Brenham: -29.70College Station: -27.10Columbus: -29.05Conroe: -33.00Crockett: -24.40Danevang: -24.97Galveston: -22.36Freeport: -33.00Hobby: -29.89BUSH IAH: -30.94Huntsville: -33.59Katy: -27.44Livingston: -34.88Madisonville: -31.39Matagorda: -29.93Tomball: -38.43Victoria: -26.73Corpus Christi: -18.94With 2011 over 80% complete, it is increasingly likely that both Houston Hobby and BUSH IAH will beending 2011 as either their driest or second driest years on record. For IAH the past driest year onrecord was 1917 with a yearly rainfall total of 17.66 inches. Through November 1, 2011, BUSH IAH hasrecorded 15.58 inches of rainfall which means 2.08 inches of rainfall will be required in the remaining 2months to move 2011 out of the first place ranking over 1917. Despite 5.11 inches of rainfall at HobbyAirport on the 9th, Hobby is still recording its driest Jan 1-Nov 1 period on record.The lengthy rainfall record between 1 inch rainfall events ended on October 9th for the City of Houston.BUSH IAH recorded 3.02 inches of rainfall that day. The city went an astounding 257 days between 1inch rainfall events (the previous record was only 192 days in 1917-1918). The 3.02 inches of rainfall onthe 9th was the single greatest amount of rainfall for Houston since the landfall of Hurricane Alex inMexico on July 2, 2010.Fire Weather:Conditions of fine fuels have experienced enough wetting rainfall to prevent the rapid spread ofwildfires for much of October. The new 2011-2012 fire season will begin shortly for the new time periodof reporting standards. Year to date totals indicate almost 3.9 million acres have burned or nearly thesize of the state of Connecticut. A total of 4,956 structures have been lost and 47,891 structuresthreatened but saved. Fire weather concerns will be increasing over the next several weeks as the firstkilling freezes of 2011 affect the area resulting in a heavier fuel loading of the finer fuels which havebeen helped by the recent rainfall. The larger ladder and canopy fuels remain extremely dry and it willbe easier for fire starts once the finer fuels are cured for the winter season.The threat for wind driven wildfires is expected to be significant this fire weather season across all ofTexas with critical days coming behind cold fronts. 3
  4. 4. Current KBDI Values:While current values have shown some recovery with the recent rainfall, much of the area remainsseverely dry with vegetation suffering. A KBDI value of 800 indicates the top 8 inches of soil iscompletely void of moisture.Austin: 684Bastrop: 643Brazoria: 665Brazos: 684Burleson: 721Calhoun: 648Chambers: 695Colorado: 700Fort Bend: 672Galveston: 616Grimes: 652Harris: 567Houston: 718Jackson: 707Liberty: 655Limestone: 725Madison: 706Matagorda: 643Montgomery: 608San Jacinto: 620Trinity: 675Victoria: 653Walker: 685Waller: 569Wharton: 689Washington: 690Economic Impacts:So far 5.2 billion in losses have occurred due to the drought mainly in the agriculture arena. The 5.2billion in losses surpasses the 4.1 billion record in 2006. However as lake levels continue to fall tourismand real estate are also being impacted as boat ramps close, water front property devalues, and riversrun dry. The TX Pecan harvest this year was down 20 million pounds compared to the typical crop. Amassive red tide bloom affecting much of the Texas coast has closed the Oyster harvesting seasoneffective 10-31-11 this is due in part to the lack of fresh water run-off from inland rivers reaching thebays. In fact many of the Texas bays systems continue to experience hyper-saline water conditions dueto the lack of freshwater run-off.Wheat yields were down about 800,000 acres of harvest, corn suffered heavily yield down 40% andnearly 80% of the crop failed. Sorghum yield was down about 50%. A staggering 52% of the cotton cropwas abandoned in 2011 adding up to about 1.8 billion dollars in loss.Across Texas grass has long since died during the hot summer months and cattle and wildlife continue tosuffer. Truck loads of hay are being brought to Texas to supplement the declining supplies of feed and itis estimated that 10,000 head of cattle have been relocated to other areas of the country that can 4
  5. 5. sustain their needs. A combination of severely reduced feed and lowering water supplies has had a largeeffect on the ability of cattle to survive in the current conditions.Vegetation:Trees continue to suffer across the entire state as rainfall remains generally below average. Droughtstress has led to the invasion of harmful disease and pest that can attack and kill weakened trees. Manytrees went dormant in late summer due to lack of water shedding their leaves and it will be determinednext spring as to which and how many will survive. Pines and Water Oaks have taken the hardest hit andit is estimated that at least 2-3 million trees have died in Harris and the immediate surrounding countiesand that an additional 66-80 million will die in the next 2 years….a staggering loss of the area treecanopy. Even native trees such as Cedar and Juniper and showing signs of drought stress and Cedartrees in the Waco/Temple corridor have begun to die from lack of water.Water Supply:Recent rains have helped slow the tremendous losses of late summer, but declines continue on mostwater supply lakes. There was some recovery on the lakes across N TX with the recent rainfall, but onlyon the order of 2-3 feet. The current total storage for the state of Texas is 31,831,330 acre feet or58.95% full. At the start of October the state storage was 60.14% full, so even with the recent rainfallthe overall storage continues to decline mainly due to the lack of inflow from dry rivers and streams.In middle October the City of Houston increased its water withdrawal from Lake Conroe to 165 milliongallons per day and this will remain in effect through the end of 2011 unless significant rain falls. LakeThis drawdown is currently resulting in about ½ of an inch of loss to the conservation pool per day oraround 17 inches per month. With no additional rainfall Lake Conroe will continue to decline at 1-1.5feet per month through the end of 2011. At the start of 2011 the City of Houston can once again call ontheir water rights to Lake Conroe and request releases. Conroe is currently at 193.53 ft or 2.47 ft belowits record low pool elevation. Normal conservation pool is 201 ft.Current forecast projections for the Highland Lakes chain on the Colorado River indicate that withoutsignificant rainfall the combined storage could drop to between 680,000-640,000 acre feet by the startof 2012 nearing the 600,000 acre foot mark of their drought of record in the 1940’s-1950’s. To give anidea of just how severe the drought has been over central Texas, in a typical year the average inflow intothe Highland Lakes from Jan-Sept is around 991,848 acre feet, in 2011 through the end of Septemberthe inflow has been 74,719 acre feet an astounding lack of water in flow into these lakes. Lake Travis iscurrently down almost 54.0 ft.Lake Somerville lost another 4% of its storage conservation pool in the last month dropping from 42% to38% with rainfall. 5
  6. 6. Lake levels below conservation pool and current capacity on Nov 2:Lake Conroe: -5.47 (69%)Lake Houston: -5.68 (77%)Lake Buchanan: -30.83 (38%)Lake Travis: -53.96 (35%)Toledo Bend: -12.15 (58%)Lake Livingston: -3.88 (82%)Lake Somerville: -10.22 (38%)Lake Georgetown: -24.84 (35%)Sam Rayburn: -13.52 (55%)Lake Texana: -11.99 (43%)Forecast:For the first time in many months the CPC maps show a chance of above average rainfall over the next6-14 days over mainly the eastern part of Texas. This is in response to a large trough over the westernUS allowing a long fetch of Gulf moisture to interact with a noisy and somewhat moist upper level SWflow aloft. While the models are showing this pattern change with the chances of widespread rainfall,time and time again we have seen the drought outperform the model guidance, but at least there is ahopeful pattern for some rainfall over the next week.The longer term trend is not as favorable for the state as La Nina conditions have redeveloped in thecentral Pacific which is common coming off such a strong La Nina last winter. This increases the odds ofa drier than average winter and spring for much of Texas. While is will certainly rain from time to timeand even a couple of months could have near normal or above normal rainfall, the overall trend is forbelow average rainfall through the winter into the spring of 2012. While winter rains tend to be morewidespread than the summer isolated rains they also tend to be lighter. As stated earlier a fewwidespread rain events will not end this drought, a continued patterned amount of rainfall is needed torecover soil moisture and return streams to base flow conditions which would help inflow into areawater supply systems. Until this happens water levels will continue to decline and the outlook for belowaverage rainfall into 2012 does not bode well for a lessening of the current drought. 6