Friday, May 29, 2015

Epic Rains, Disastrous Floods Plague Texas, Oklahoma - Moderate Drought Covering All of Massachusetts, Connecticut, and Rhode Island

Damage along River Road in Wimberley, Texas, from a devastating flash flood on Saturday night, May 23. (Photo Credit: Jerry Lara/The San Antonio Express-News, via AP) Click to Enlarge.
Water cascaded through the streets, creeks, and bayous of downtown Austin and Houston on Monday as an upper-level storm inched its way across the southern Great Plains.  Slow-moving thunderstorms dumped 6” to 8” across the western Houston metro area between 8:00 and 11:00 p.m., and heavy rains continued well past midnight across much of the south and west metro area, bringing some totals as high as 10+”.  Though the Houston flooding came well short of that in 2001’s catastrophic Tropical Storm Allison, countless roads and interstate highways were submerged, and hundreds of homes reportedly took water.  This was the latest salvo in a remarkable three-day stretch of torrential rain and destructive flooding across much of Oklahoma and Texas and parts of neighboring states.  As of Tuesday morning, the floods had taken at least 8 lives, with at least 12 people missing, and damaged or destroyed many hundreds of buildings.
Precipitation persistence: the story of 2015
One of the most intriguing questions in climate change research is whether blocking-type patterns might be fostered by rising global temperatures and the resulting effects on jet-stream behavior.  Over the last month, the same pattern favoring heavy rain across Texas and Oklahoma has kept rain away from the Northeast.  It was just three months ago that an unprecedented month-long stretch of heavy snowfall brought Boston and much of New England to its frosty knees.  A couple of individual snowstorms within that stretch were among Boston’s heaviest, but it was the relentlessness of the cold, snowy conditions that truly stood out and caused such misery.  Likewise, the unrelenting rainfall across the southern Plains this month has caused pile-on effects, as downpours flow off saturated soil and farmers struggle to get spring crops planted.  During the 30 days ending on May 25, Norman, OK, received an astounding 24.10”.  Oklahoma is now assured of its wettest month on record, according to the Oklahoma Climatological Survey.

Here are some individual locations that have already set records for their wettest May as of midnight Monday night, with nearly a week left to go in the month.  (Thanks to Nick Wiltgen at the Weather Channel for compiling these statistics.)
  • Oklahoma City, OK: 18.85” (previous May record 14.52” in 2013; previous all-time record 14.66” in June 1989)
  • Fort Smith, AR: 18.07” (previous May record 13.67” in 1943; previous all-time record 15.02” in June 1945)
  • Austin, TX (Camp Mabry): 16.72” (previous May record 14.10” in 1895; all-time record 20.78” in Sept. 1921)
  • Wichita Falls, TX: 14.15” (previous all-time record 13.22” in May 1982)
Meanwhile, back in the Northeast, the tables have turned in a way that might have seemed hard to fathom three months ago.  The most recent U.S. Drought Monitor shows moderate drought (D1) covering all of Massachusetts, Connecticut, and Rhode Island, as well as parts of New York, Maine, and Pennsylvania.  Even the enormous snowfalls of February didn’t contain especially large amounts of moisture compared to what can fall in a midwinter New England rainstorm, and the tap hasn’t been flowing much at all lately.  In the 30 days ending on May 26, less than an inch of rain fell across most of New Jersey, southeast New York, and southern New England, with some locations getting little more than sprinkles.  Further south, only a trace has fallen this month in Charlotte, North Carolina.  Reservoirs and water tables in New England are still in relatively good shape, but streamflows are quite low.  Potential records for driest or second-driest May at locations with more than a century of data include:
  • Concord, NH: 0.07” (record low 0.50”, 2008; records begin in 1903)
  • Providence, RI: 0.51” (record low 0.57”, 1939; records begin in 1904)
  • Hartford, CT: 0.60” (record low 0.73”, 1959; records begin in 1905)
  • Boston, MA: 0.31” (record low 0.25”, 1944; runner-up 0.32”, 1903; records begin in 1872)
  • Albany, NY: 0.31” (record low 0.15”, 1903; runner-up 0.73”, 1920; records begin in 1874)
  • New York, NY (Central Park): 0.32” (record low 0.30”, 1903; runner-up 0.34”, 1887; records begin in 1871).

Read more at Epic Rains, Disastrous Floods Plague Texas, Oklahoma

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