April 2016 North American storm complex

Apr 27, 2026 - 05:00
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April 2016 North American storm complex

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== Meteorological history ==
== Meteorological history ==
[[File:April 20, 2016 7-Day Observed Precipitation near Houston, Texas.png|thumb|left|Map of accumulated precipitation in and around Houston, Texas, from April 13 to 20.]]
[[File:April 20, 2016 7-Day Observed Precipitation near Houston, Texas.png|thumb|left|Map of accumulated precipitation in and around Houston, Texas, from April 13 to 20.]]
In mid-April 2016, a large, slow-moving [[upper-level low]] emerged from the [[Four Corners]] region in [[Rocky Mountains]] over the [[Central United States]].{{cite news|author=Angela Friz|newspaper=The Washington Post|date=April 14, 2016|access-date=April 20, 2016|title='Omega block' will create warmth and sun for some, feet of snow for others|url=https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/04/14/omega-block-will-create-warmth-and-sun-for-some-feet-of-snow-for-others/}} Simultaneously, a [[ridge (meteorology)|ridge]] became anchored over the [[Eastern United States]] with another low to the east, creating an [[omega block]]—a stagnant weather pattern. The low near the Rockies pulled large quantities of moisture north from the [[Gulf of Mexico]], leading to both heavy snow in the mountains and widespread heavy rain to the plains.{{cite report|author=Allison Ann Santorelli|publisher=Weather Prediction Center|date=April 17, 2016|access-date=April 20, 2016|title=Storm Summary Number 01 for Central and Southern Plains Heavy Rainfall|url=http://www.wpc.ncep.noaa.gov/winter_storm_summaries/storm12/stormsum_1.html|location=College Park, Maryland}} During the overnight hours of April 15–18, a nearly stationary [[mesoscale convective system]] developed over the [[Houston Metropolitan Area]]. Southeasterly flow from a [[low level jet]] fueled the system with ample moisture, leading to widespread rainfall rates of {{convert|2|in|mm|abbr=on}} per hour.{{cite report|author=Gregory M. Gallina|publisher=Weather Prediction Center|date=April 17, 2016|access-date=April 20, 2016|title=Mesoscale Precipitation Discussion 0127|url=http://www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=0127&yr=2016|location=College Park, Maryland}} Rainfall intensified throughout the night into the morning of April 18 with rainfall rates reaching {{convert|4|in|mm|abbr=on}} per hour, leading to a life-threatening situation.{{cite report|author=Gregory M. Gallina|publisher=Weather Prediction Center|date=April 18, 2016|access-date=April 20, 2016|title=Mesoscale Precipitation Discussion 0128|url=http://www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=0128&yr=2016|location=College Park, Maryland}} At 4:39 a.m. [[Central Daylight Time|CDT]], a [[flash flood emergency]] was declared for parts of [[Colorado County, Texas|Colorado]], [[Waller County, Texas|Waller]], [[Grimes County, Texas|Grimes]], [[Montgomery County, Texas|Montgomery]], [[Harris County, Texas|Harris]], and [[Austin County, Texas|Austin]] counties,{{cite web|work=National Weather Service in Houston/Galveston, Texas|publisher=National Oceanic and Atmospheric Administration|date=April 18, 2016|access-date=April 20, 2016|title=Severe Weather Statement: Flash Flood Warning|url=http://mesonet.agron.iastate.edu/vtec/#2016-O-NEW-KHGX-FF-W-0014/USCOMP-N0Q-201604180940}} later expanding to [[Fort Bend County, Texas|Fort Bend]].{{cite web|work=National Weather Service in Houston/Galveston, Texas|publisher=National Oceanic and Atmospheric Administration|date=April 18, 2016|access-date=April 20, 2016|title=Severe Weather Statement: Flash Flood Warning|url=http://mesonet.agron.iastate.edu/vtec/#2016-O-NEW-KHGX-FF-W-0016/USCOMP-N0Q-201604181100}}
In mid-April 2016, a large, slow-moving [[upper-level low]] emerged from the [[Four Corners]] region in [[Rocky Mountains]] over the [[Central United States]].{{cite news|author=Angela Friz|newspaper=The Washington Post|date=April 14, 2016|access-date=April 20, 2016|title='Omega block' will create warmth and sun for some, feet of snow for others|url=https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/04/14/omega-block-will-create-warmth-and-sun-for-some-feet-of-snow-for-others/}} Simultaneously, a [[ridge (meteorology)|ridge]] became anchored over the [[Eastern United States]] with another low to the east, creating an [[omega block]]—a stagnant weather pattern. The low near the Rockies pulled large quantities of moisture north from the [[Gulf of Mexico]], leading to both heavy snow in the mountains and widespread heavy rain to the plains.{{cite report|author=Allison Ann Santorelli|publisher=Weather Prediction Center|date=April 17, 2016|access-date=April 20, 2016|title=Storm Summary Number 01 for Central and Southern Plains Heavy Rainfall|url=http://www.wpc.ncep.noaa.gov/winter_storm_summaries/storm12/stormsum_1.html|location=College Park, Maryland}} During the overnight hours of April 15–18, a nearly stationary [[mesoscale convective system]] developed over the [[Houston Metropolitan Area]]. Southeasterly flow from a [[low level jet]] fueled the system with ample moisture, leading to widespread rainfall rates of {{convert|2|in|mm|abbr=on}} per hour.{{cite report|author=Gregory M. Gallina|publisher=Weather Prediction Center|date=April 17, 2016|access-date=April 20, 2016|title=Mesoscale Precipitation Discussion 0127|url=http://www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=0127&yr=2016|location=College Park, Maryland}} Rainfall intensified throughout the night into the morning of April 18 with rainfall rates reaching {{convert|4|in|mm|abbr=on}} per hour, leading to a life-threatening situation.{{cite report|author=Gregory M. Gallina|publisher=Weather Prediction Center|date=April 18, 2016|access-date=April 20, 2016|title=Mesoscale Precipitation Discussion 0128|url=http://www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=0128&yr=2016|location=College Park, Maryland}} At 4:39 a.m. [[Central Daylight Time|CDT]], a [[flash flood emergency]] was declared for parts of [[Colorado County, Texas|Colorado]], [[Waller County, Texas|Waller]], [[Grimes County, Texas|Grimes]], [[Montgomery County, Texas|Montgomery]], [[Harris County, Texas|Harris]], and [[Austin County, Texas|Austin]] counties,{{cite web|work=National Weather Service in Houston/Galveston, Texas|publisher=National Oceanic and Atmospheric Administration|date=April 18, 2016|access-date=April 20, 2016|title=Severe Weather Statement: Flash Flood Warning|url=http://mesonet.agron.iastate.edu/vtec/#2016-O-NEW-KHGX-FF-W-0014/USCOMP-N0Q-201604180940}} later expanding to [[Fort Bend County, Texas|Fort Bend]].{{cite web|work=National Weather Service in Houston/Galveston, Texas|publisher=National Oceanic and Atmospheric Administration|date=April 18, 2016|access-date=April 20, 2016|title=Severe Weather Statement: Flash Flood Warning|url=http://mesonet.agron.iastate.edu/vtec/#2016-O-NEW-KHGX-FF-W-0016/USCOMP-N0Q-201604181100}} In 12 hours from April 17 to 18, {{convert|12|in|mm|abbr=on}} to {{convert|16|in|mm|abbr=on}} of rainfall fell in Houston, causing flash flooding.{{Cite web |last=Barker |first=Aaron |date=2019-04-16 |title=Look back at Houston’s 2016 ‘Tax Day Flood’ |url=https://www.click2houston.com/weather/2019/04/16/look-back-at-houstons-2016-tax-day-flood/ |access-date=2026-04-26 |website=KPRC |language=en}} Known as the Tax Day flood, the flooding caused at least five deaths and damaged over 10,000 homes in the Houston area.{{Cite web |last=Alfonso III |first=Fernando |date=2018-04-13 |title=A look back at the devastation caused in Houston by the tax day flood of 2016 |url=https://www.chron.com/news/houston-texas/houston/article/tax-day-flood-houston-2016-photos-looking-back-12832654.php |access-date=2026-04-26 |website=Chron |language=en}}{{Cite web |last=Smith |first=Elyse |date=2026-04-22 |title=2016 Tax Day flood study highlights expansive flood threat for Houston, Harris County |url=https://abc13.com/post/2016-tax-day-flood-study-highlights-expansive-threat-houston-harris-county/18943582/ |access-date=2026-04-26 |website=ABC13 Houston |language=en}}


Accumulations peaked at {{convert|17.6|in|mm|abbr=on}} along Little Mound Creek at Mathis Road to the northwest of Houston. Other significant totals include {{convert|16.48|in|mm|abbr=on}} along Cypress Creek at Sharp Road, {{convert|16.32|in|mm|abbr=on}} along Langham Creek at Longenbaugh, and {{convert|16.22|in|mm|abbr=on}} in [[Monaville, Texas|Monaville]]. [[George Bush Intercontinental Airport]] saw {{convert|9.92|in|mm|abbr=on}},{{cite report|author=Jason A. Krekeler |publisher=Weather Prediction Center |date=April 20, 2016 |access-date=April 20, 2016 |title=Storm Summary Number 11 for Central and Southern Plains Heavy Rainfall |url=http://www.wpc.ncep.noaa.gov/winter_storm_summaries/storm12/stormsum_11.html |location=College Park, Maryland |archive-date=May 3, 2016 |archive-url=https://web.archive.org/web/20160503095526/http://www.wpc.ncep.noaa.gov/winter_storm_summaries/storm12/stormsum_11.html |url-status=dead }} bringing the monthly rainfall total to {{convert|11.38|in|mm|abbr=on}}. This marked the wettest April on record for Houston.{{cite web|work=National Weather Service Office in Houston/Galveston, Texas|publisher=National Oceanic and Atmospheric Administration|date=April 20, 2016|access-date=April 20, 2016|title=...Houston's April Top 10 List...|url=http://www.srh.noaa.gov/hgx/?n=climate_iah_top10_apr}}
Accumulations peaked at {{convert|17.6|in|mm|abbr=on}} along Little Mound Creek at Mathis Road to the northwest of Houston. Other significant totals include {{convert|16.48|in|mm|abbr=on}} along Cypress Creek at Sharp Road, {{convert|16.32|in|mm|abbr=on}} along Langham Creek at Longenbaugh, and {{convert|16.22|in|mm|abbr=on}} in [[Monaville, Texas|Monaville]]. [[George Bush Intercontinental Airport]] saw {{convert|9.92|in|mm|abbr=on}},{{cite report|author=Jason A. Krekeler |publisher=Weather Prediction Center |date=April 20, 2016 |access-date=April 20, 2016 |title=Storm Summary Number 11 for Central and Southern Plains Heavy Rainfall |url=http://www.wpc.ncep.noaa.gov/winter_storm_summaries/storm12/stormsum_11.html |location=College Park, Maryland |archive-date=May 3, 2016 |archive-url=https://web.archive.org/web/20160503095526/http://www.wpc.ncep.noaa.gov/winter_storm_summaries/storm12/stormsum_11.html |url-status=dead }} bringing the monthly rainfall total to {{convert|11.38|in|mm|abbr=on}}. This marked the wettest April on record for Houston.{{cite web|work=National Weather Service Office in Houston/Galveston, Texas|publisher=National Oceanic and Atmospheric Administration|date=April 20, 2016|access-date=April 20, 2016|title=...Houston's April Top 10 List...|url=http://www.srh.noaa.gov/hgx/?n=climate_iah_top10_apr}}


At the same time, the upper low produced a major [[snowstorm]] in the [[Rocky Mountains]] and [[High Plains (United States)|High Plains]] from April 16–17. Due to the omega block, snowfall remained concentrated around the [[Denver metropolitan area]]s. Because of this, some snowfall totals ranged up to {{convert|3–4|ft|in}} in some areas. This definitely led to areas coming close to breaking their top-snowiest days in April. A climate study analyzing the 2015 flood in Texas and Oklahoma{{cite journal|last=Simon Wang|first=S.-Y.|first2=W.-R.|last2=Huang|first3=H.-H.|last3=Hsu|first4=R. R.|last4=Gillies|date=16 October 2015|title=Role of the strengthened El Niño teleconnection in the May 2015 floods over the southern Great Plains|journal=Geophysical Research Letters|volume=42|issue=19|pages=8140–8146|doi=10.1002/2015GL065211|bibcode=2015GeoRL..42.8140S|url=https://digitalcommons.usu.edu/psc_facpub/749|doi-access=free}}. has found an intensified El Niño effect on the climatologically wet season of spring, and the [http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015GL065211/full intensification] has a trace of anthropogenic climate warming.
At the same time, the upper low produced a major [[snowstorm]] in the [[Rocky Mountains]] and [[High Plains (United States)|High Plains]] from April 16–17. Due to the omega block, snowfall remained concentrated around the [[Denver metropolitan area]]s. Because of this, some snowfall totals ranged up to {{convert|3–4|ft|in}} in some areas. This definitely led to areas coming close to breaking their top-snowiest days in April. A climate study analyzing the 2015 flood in Texas and Oklahoma{{cite journal|last=Simon Wang|first=S.-Y.|first2=W.-R.|last2=Huang|first3=H.-H.|last3=Hsu|first4=R. R.|last4=Gillies|date=16 October 2015|title=Role of the strengthened El Niño teleconnection in the May 2015 floods over the southern Great Plains|journal=Geophysical Research Letters|volume=42|issue=19|pages=8140–8146|doi=10.1002/2015GL065211|bibcode=2015GeoRL..42.8140S|url=https://digitalcommons.usu.edu/psc_facpub/749|doi-access=free}}. has found an intensified El Niño effect on the climatologically wet season of spring, and the [http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015GL065211/full intensification] has a trace of anthropogenic climate warming.


The upper low began to move eastward on April 19, as the omega block began to break down. It was expected to reach the [[East Coast of the United States|East Coast]] by April 22, with much less rainfall totals as it began to accelerate.
The upper low began to move eastward on April 19, as the omega block began to break down. It was expected to reach the [[East Coast of the United States|East Coast]] by April 22, with much less rainfall totals as it began to accelerate.
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