the science of drought and flood prediction

ANTHONY R. LUPODEPARTMENT OF SOIL , ENVIRONMENTAL,

AND ATMOSPHERIC SCIENCE

The Science of Drought and Flood Prediction

Introduction

The summer of 2012 in Missouri was very dry and hot. The mean summer season temperature ranked only about sixth warmest across our region. (26.9o C or 80.3o F in Mid-MO). (behind 1934, 1936, 1980, 1954, 1901).

Precipitation – ranked as only the 10th driest summer thanks to a last second reprieve from Isaac with 145.3 mm (5.72”) (June 1 – August 31).

http://www.nhc.noaa.gov/HAW2/english/history.shtml

Introduction

How last minute? SKY/WX TMP DP RH WIND PRES REMARKS1255 AM FAIR 79 60 52 SE5 30.00S 6HR MIN TEMP: 79; 6HR MAX TEMP: 93; 155 AM CLEAR 78 64 61 SE5 30.00S 255 AM CLEAR 77 65 66 E6 30.00S 355 AM PTCLDY 76 66 71 E6 29.99F 455 AM MOCLDY 77 67 71 E7 29.98F 555 AM CLOUDY 77 67 71 E9 29.98S 655 AM CLOUDY 77 67 71 E9 29.98S 6HR MIN TEMP: 76; 6HR MAX TEMP: 79; 6HR PCP: TRACE; 755 AM RAIN 74 69 85 E10 29.99R 855 AM HVY RAIN 73 70 90 E15G21 29.99S FOG 955 AM HVY RAIN 73 71 93 E14G22 29.99S FOG 1055 AM HVY RAIN 74 72 93 NE17G26 29.96F FOG 1155 AM RAIN 74 72 93 E20G29 29.93F FOG 1255 PM LGT RAIN 74 32 21 E16G24 29.93S 6HR MIN TEMP: 73; 6HR MAX TEMP: 74; 6HR PCP: 1.76; 155 PM LGT RAIN 75 73 93 E17G28 29.89F 255 PM CLOUDY 76 74 93 E14G23 29.87F 355 PM CLOUDY 79 75 89 E20G26 29.83F 455 PM RAIN 76 74 93 E16G23 29.82F FOG 555 PM LGT RAIN 75 73 93 SE12G21 29.82F 655 PM LGT RAIN 75 73 93 E13G21 29.82S 6HR MIN TEMP: 74; 6HR MAX TEMP: 78; 6HR PCP: 0.18; 755 PM CLOUDY 73 73 100 E10 29.82S 855 PM RAIN 73 73 100 E12G20 29.82S FOG 955 PM LGT RAIN 74 73 97 E10 29.83S FOG 1055 PM RAIN 74 73 97 SE12 29.82F FOG 1155 PM CLOUDY 75 73 93 E9 29.81S

Introduction

If we combine temperature and precipitation rankings EVEN WITH Isaac, 2012 is the 4th worst summer behind 1936, 1980, and 1901. (Remove Isaac and 2012 surpasses 1901).

Nation-wide, the drought had severe impacts all across the economy.

Introduction

From the US drought monitor: (Aug 28th, 2012) (http://droughtmonitor.unl.edu)

Introduction

From the US drought monitor: (February 19th, 2013) (http://droughtmonitor.unl.edu)

Introduction

Drought, or flooding such as experienced in 1993 or 1995, generally do not happen quickly. These take months to build up to and months to dissipate (2012 – go back to summer 2011).

“Flash drought” can happen quickly and be quite severe. (e.g., Russia 2010). We’ll deal with this later.

Definition

Drought - Basic drought equation: precipitation minus evaporation

If evaporation exceeds precipitation for a period of time, the result is a drought.

Meteorological drought compares P-E to climatology

Definitions

Different types of drought

Meteorological precipitation versus normal

Agricultural stress on plants

Hydrological level of the rivers and lakes

Meteorological Situation

500 hPa ridge amplified over the central USA (1 June – 31 Aug, 2012)

Meteorological Situation

Summer 500 hPa and 850 hPa maps (from Lupo et al. (2012))

1970 (dry – 9.63) 2001 (normal) 1976 (driest)

EN -> LA Neu -> Neu LN -> weak EL

Drought in the Midwest

The impact of El Nino.

El Nino, what is it?

El Niño –means literally “the child”, in this case, THE Child as El Niño typically sets in around Christmas on the coast of South America!

http://www.diopitt.org/creche_holyfamilylarge.gif


El Niño (or ENSO – El Niño and Southern Oscillation) is the generic term referring to the see-saw of warm (El Niño) and cold (La Niña) sea surface temperature patterns in the eastern Tropical Pacific

This occurs every 2 – 7 years!


El Nino:


Currently: (ENSO-neutral) (Source: Climate Prediction Center)


Forecasts persist in projecting neutral conditions for the rest of the year and range from weak La Nina to weak El Nino conditions.


Ratley (Ratley, Baxter, Lupo) et al. 2002 discussed the onset of the summer regime in the mid-west and it’s relation to ENSO.

They noticed that before the summer regime becomes “established”, significant rains (widespread and more than 0.25 inches) fall on average every 7 days.

This becomes every 12 days after the onset of the summer pattern.


They then found that in summers involving the transition into a (future) El Nino situation, the mean precipitation frequency in spring and summer is 6 days and 10 days, respectively. (e.g., summer 1993, summer 2004)

For the transition into a La Nina situation, the corresponding numbers are 8 days, and 19 days, respectively. (e.g., summer 1983, 1988, 1999, 2005, 2012 and historically, the severe dry spell of the 1950’s)


Thus, they found that in the Missouri region, there is not a significant difference region-wide in precipitation amounts year-to-year, but the frequency of heavy precipitation is markedly different. (exceptional years it may be less or more as well).

It is well-known in the agricultural community that lighter, more frequent (regular) precipitation events are much better for crops.


The results of Ratley et al. (2002) are based on 30 years worth of data. Results from this extended work (Birk and Lupo (2010) paper) support the results given here.

Currently working on a similar analysis for Western Russia. Results demonstrate that ENSO transition is correlated with drought there as well (Lupo et al., 2012, conference paper).


What is the role of climate and climate change on drought?

Let’s look at the decadal record for the USA. We had drought years in this part of the country during the 1910’s 1930s, 1950’s, 1980, 1983, 1988, 1999, 2003, 2005, 2012 (but wet years in 1993 and 1995).


Borrowed from Karl and Knight (1998), BAMS

Borrowed from Hu et al. (1998), BAMS


Climate change may impact the temporal and/or spatial distribution and severity of drought, however, drought and pluvials (wet spells) will still occur.

Let’s look at a couple centuries…….


year

1930 1940 1950 1960 1970 1980 1990 2000

Pal

mer

Dro

ught

Sev

erity

Inde

x (P

DS

I)

-8

-6

-4

-2

0

2

4

6

8

• Borrowed from the Missouri Tree-Ring Laboratory

• Stambaugh, M.C. and R.P. Guyette. 1000 years of tree-ring reconstructed drought in the Central United States.

Paleoecological understanding

16th Century Megadrought

Little Ice Age

Maunder Minimum

1816, Year without summer

Medieval Warm Period

Dust Bowl

Stambaugh, M.C. and R.P. Guyette. (in prep). 1000 years of tree-ring reconstructed drought in the Central United States.


Borrowed from Fye et al. (2003), BAMS


Precipitation in the Northern Plains (Borrowed from Woodhouse and Overpeck, (1998), BAMS


Studies have shown that the US climate has been getting wetter.

What does the future hold? Model studies have shown our region may be drier (e.g., IPCC), and some studies have shown it may be wetter (e.g. Semenov et al., 2003, Climate Dynamics).


Many regions of the country give similar mixed results, but since drought and wet spells are seasonal in nature (and driven by SST and atmospheric variations) they will continue to occur regardless of what the climate does!

Forecast 2013

What’s in store for 2013?

Forecast 2012

Our group predicted a relatively dry and warmer than normal summer 2012 regionally based on a few factors.

1) For 6 of the past 12 months before there had precipitation amounts below to well-below normal (4), while four months have been very wet. Winter and spring temps were well above normal though.

Forecast 2012

2) During the late winter, early spring, weak La Nina conditions persisted in the eastern tropical Pacific. At the time, this was expected to persist through the spring and summer.

3) we’d also projected a drier spring, which did occur. The late spring/early summer (June) were in-line with our predictions.

Winter 2012 - 2013 (Mid MO)

Predictions were for a warmer than normal winter, and drier than normal with precipitation and less snow than normal. http://weather.missouri.edu/gcc/

For December, we’re warmer than normal, a bit dry with less snow than normal. A decent forecast (so far….) on our part!

http://weather.missouri.edu/gcc/

Spring 2013

Spring Temps – March April May

Spring 2013

Spring Precipitation: March April May

Summer 2013

CPC Summer temps - JJA

Summer 2013

CPC Summer Precipitation

Summer 2013

CPC forecast is for a warm summer, with the inference that the later summer will be cooler. This may reflect the ENSO neutral conditions?

No precipitation forecast. They always punt!

Famous “double header” dry summers: 1916 – 1917, 1953 – 1954, 1971-1972.

the science of drought and flood prediction

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