record-breaking rainfall and flooding associated with hurricane … · 2019-07-16 · outline 1....
TRANSCRIPT
![Page 1: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/1.jpg)
Record-Breaking Rainfall and Flooding Associated with Hurricane Florence: Is This the New Normal?
Chip KonradNOAA Carolina Integrated Science and Assessments
(CISA)NOAA Southeast Regional Climate Center
Department of GeographyUniversity of North Carolina at Chapel Hill
![Page 2: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/2.jpg)
Outline
1. Overview of Hurricane Florenceo History & evolutiono Heavy rainfall & flooding impacts
2. Historical trends in the character of hurricanes & controlling factorso Character: frequency, intensity & rate of developmento Controlling factors: Sea surface temperature, vertical wind shear,
atmospheric dust, El Nino & La Nina
3. Influences on Heavy Rainfall and Floodingo Hurricane translation speedo Lengthening of core of hurricane season & interactions with mid-
latitude circulation features
4. Future trends in hurricanes and heavy rainfall & flooding
![Page 3: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/3.jpg)
Hurricane Florence. September 2018
• Very slow moving and large
![Page 4: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/4.jpg)
CAT 4
CAT 2CAT 1
Florence track and intensity
Very slow moving
![Page 5: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/5.jpg)
Sea Surface Temperatures above normal
![Page 6: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/6.jpg)
From Tropical Tidbits
![Page 7: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/7.jpg)
Florence total precipitation
Multi-sensor rainfall estimates from Hurricane Florence produced by National Weather Service Eastern Region Headquarters.
![Page 8: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/8.jpg)
![Page 9: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/9.jpg)
Many areas experienced the 1000 year and longer heavy rain event over a 3 day period
![Page 10: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/10.jpg)
Road closures in the wake of Hurricane Florence
• Wilmington became a virtual island separated from the mainland
• Numerous rural areas isolated for a week or more
• Many rural people, especially the elderly, in poor health and had no access to health care.
![Page 11: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/11.jpg)
Historical trends in hurricane attributes and controlling factors
http://www.euroargo-edu.org/argoeu_4.php
Average SST temperatures in September SSTs are above normal much of time now
http://www.ospo.noaa.gov/Products/ocean/sst/anomaly/
A. Sea Surface Temperature
![Page 12: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/12.jpg)
Increases in Global Sea Surface Temperature (SST)
http://www.realclimate.org/index.php/archives/2011/07/revisiting-historical-ocean-surface-temperatures/
![Page 13: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/13.jpg)
Hurricanes driven by heat in ocean
1. Increasing wind speeds
3. Increasing water vapor flux4. More condensation
5. More sensible heating6. Accelerating Updraft
8. Decreasing surface pressure
9. Increasing surface pressure gradient 2. Increasing evaporation7. More air leaving surface than
coming in from periphery
B. Moist environment – no dry air
C. Low Wind Shear
A. Warm Sea Surface
Factors that control frequency of hurricanes and their strength
![Page 14: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/14.jpg)
• Increase in cases of rapid intensification
Both Michael and Florence intensified rapidly in 2019
![Page 15: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/15.jpg)
Atlantic Multi-decadal Oscillation (AMO)
Climate Variability
![Page 16: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/16.jpg)
From Blake et al. 2011
![Page 17: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/17.jpg)
El Nino – Westerly upper level winds over subtropical Atlantic
• More vertical wind shear, less hurricanes, & steering of hurricanes away from coast
La Nina – Easterly upper level winds over subtropical Atlantic
• Less vertical wind shear, more hurricanes, more steered towards U.S. coast
Climate variability continued
El Nino and La Nina events affect vertical wind shear and tropical cyclone tracking.
Recall that low wind shear (i.e. little change in large circulation through the atmospheric column) supports development of hurricanes
![Page 18: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/18.jpg)
El Nino events have increased in frequencyLa Nina events have decreased in frequency
La Nina
El Nino
Trends in Factors that control frequency and strength
![Page 19: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/19.jpg)
Decreases in Vertical Wind Shear
Vertical Wind Shear over Main Development Region of Atlantic
Garner et al (2009)
27% decrease
Recall that low wind shear (i.e. little change in large circulation through the atmospheric column) supports development of hurricanes
![Page 20: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/20.jpg)
Atmospheric dust
• Dust reflects incoming sunlight à cooler SSTs over periods of weeks/months
http://www.accuweather.com/en/weather-glossary/saharan-dust-how-does-it-devel-1/14307927
![Page 21: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/21.jpg)
Saharan dust concentrations affected by many factors
http://www.nature.com/nature/journal/v531/n7595/abs/nature17149.html
- No significant trend over time
![Page 22: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/22.jpg)
Influences on Heavy Rainfall and Flooding
• Warmer atmosphere can hold more water vapor1°C temperature increase = 7% increase in moisture atmosphere can hold
• Warmer Sea Surface Temperature à increased evaporation rate à more water vapor à higher rates of precipitation.
• Hurricanes and tropical storms can therefore produce higher rainfall rates
![Page 23: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/23.jpg)
-10.0% Globally-12.2% Northern Hemisphere-20.0% Land areas around Atlantic Basin
Decreases in Tropical Cyclone Translation Speed
Influences on Heavy Rainfall and Flooding
Kossin, James P Nature (2017)
More wetter & slower hurricanes à Heavier rainfall rates over a longer duration
![Page 24: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/24.jpg)
Extraordinary rainfall amounts when hurricanes stall out
Hurricane Harvey (2017)
5 Day Rainfall Total based on rivers and bayous (courtesy of the West Gulf River Forecast Center)
![Page 25: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/25.jpg)
L
Factors contributing to the heavy rainfallA. Nearly stationary upper level low with persistent lifting across SC
LB. Coastal front and low-level jet providing moisture
C. Additional moisture contribution from Hurricane Joaquin
D. Sea surface temperatures much above normal
Illustration developed by C.E. Konrad SERCC
Extreme Precipitation & Flooding Event across SC & SE NC in October 2015
Lengthening of core of hurricane season & interactions with mid-latitude circulation features
![Page 26: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/26.jpg)
Extreme Precipitation & Flooding Event in October 2015
From Carolinas Integrated Science & Assessment (CISA) reporthttp://www.cisa.sc.edu/PDFs/October%202015%20Flood%20Event%204%20Pager.pdf
![Page 27: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/27.jpg)
Hurricane Matthew in October 2016
![Page 28: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/28.jpg)
https://www.wpc.ncep.noaa.gov/tropical/rain/floyd1999.html
Hurricane Floyd (and Dennis)
https://www.weather.gov/mhx/Sep161999EventReview
• Hurricanes tend to be clustered in space & time
![Page 29: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/29.jpg)
-84 -82 -80 -78 -76 -74 -72 -70
28
30
32
34
36
38
40
42
L
Precipitable water 200 mb divergence Surface Pressure
Phasing of upper-level divergence (ahead of upper-level trough) with record-breaking levels of moisture
front
Interaction of mid-latitude dynamics and Hurricane Floyd (1999
![Page 30: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/30.jpg)
What about the Future?
Model projections
a. All models project increases in sea surface temperatures (SSTs): Hurricanes é
b. Many models project increases in wind shear: Hurricanes ê
c. Many models project decreases in Saharan dust: Hurricanes é
Various questions remain:
e.g. What about future frequencies of El Nino and La Nina events?
• No change to slight decrease in tropical cyclones and weak hurricanes
• Increase in strong hurricanes
![Page 31: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/31.jpg)
What about the future?
Stronger & wetter hurricanes coupled with sea level rise and coastal development & population growth à Big increase in extreme flooding.
6 of the 7 $10 billion+ hurricanes have occurred in the past 12 years, all impacting parts of the Southeast region
The costliest hurricanes to affect the United States (1900-2017)
![Page 32: Record-Breaking Rainfall and Flooding Associated with Hurricane … · 2019-07-16 · Outline 1. Overview of Hurricane Florence o History & evolution o Heavy rainfall & flooding impacts](https://reader035.vdocuments.net/reader035/viewer/2022070823/5f2a1d84afc593097f49f9b0/html5/thumbnails/32.jpg)
QUESTIONS?
Dr. Chip Konrad
NOAA Carolina Integrated Science and Assessments (CISA)
NOAA Southeast Regional Climate Center
E-mail: [email protected]