A Multiscale Analysis of a Heavy Rainfall Event over Lake Michigan

A MULTISCALE ANALYSISOF A HEAVY RAINFALL EVENT

OVER LAKE MICHIGAN

Jason M. CordeiraDEPARTMENT OF ATMOSPHERIC AND ENVIRONMENTAL SCIENCES

UNIVERSITY AT ALBANY, STATE UNIVERSITY OF NEW YORK

NROW XIIIWednesday 2 November 2011

Nicholas D. MetzDEPARTMENT OF GEOSCIENCE

HOBART AND WILLIAM SMITH COLLEGES

OBJECTIVES

• To investigate far-upstream precursors to heavy rainfall events (HREs) in the Great Lakes region

• To investigate the possible role of Lake Michigan (LM) on difficult to predict HREs in the Great Lakes region

OUTLINE

• Motivation

• Radar overview

• Far-upstream precursors

• Synoptic-scale and mesoscale analysis

• WRF simulation

OUTLINE

• Motivation

• Radar Overview



• WRF simulation

MOTIVATION – PRECIPITATION TOTALS

• 48-h precipitation totals >150 mm (>6 in) over LM

• 48-h precipitation totals ~100 mm (~4 in) over northern Indiana

image source: http://nmq.ou.edu

48-h precipitation totals ending 0000 UTC 2 July 2011

• Valparaiso, IN– 91.7 mm precipitation on 1 July 2011– 100.8 mm precipitation in 24-h period ending 0000 UTC 2 July 2011– 30-d precipitation ending 0000 UTC 1 July 2011: 87.4 mm– 30-d precipitation ending 0000 UTC 2 July 2011: 188.2 mm– 1-in-5-yr event (http://hdsc.nws.noaa.gov/hdsc/pfds/)

image source: http://nmq.ou.edu



MOTIVATION – PRECIPITATION TOTALS

• Severe weather confined to Chicago region overnight 30 June to 1 July 2011

• Subsequent severe weather event over MN, WI, IA, SD late on 1 July 2011

image source: http://www.spc.noaa.gov

30 June 2011 Storm Reports 1 July 2011 Storm Reports

MOTIVATION – SEVERE WEATHER

image courtesy ABC-7 Chicago

MOTIVATION – NAM (WRF-NMM) QPFArea-averaged accumulated precipitation (28 June forecasts)

Area-averaged domain:

NC

EP

4-k

m s

tage

IV

NAM (WRF-NMM)


NC

EP

4-k

m s

tage

IVN

AM

(W

RF

-NM

M)



NC

EP

4-k

m s

tage

IVN

AM

(W

RF

-NM

M)


Forecasts largely miss 1800 UTC 30 June to 0600 UTC 1 July precipitation

OUTLINE

• Motivation

• Radar overview– 1800 UTC 30 June – 0600 UTC 1 July 2011



• WRF simulation

RADAR OVERVIEW – 30 JUNE–1 JULY 2011

1200 UTC 30 June

image source: http://locust.mmm.ucar.edu/



1300 UTC 30 June



1400 UTC 30 June



1500 UTC 30 June



1600 UTC 30 June



1700 UTC 30 June



1800 UTC 30 June



1900 UTC 30 June



2000 UTC 30 June



2100 UTC 30 June



2200 UTC 30 June



2300 UTC 30 June



0000 UTC 1 July



0100 UTC 1 July



0200 UTC 1 July



0300 UTC 1 July



0400 UTC 1 July



0500 UTC 1 July



0600 UTC 1 July

RADAR SUMMARY – 30 JUNE–1 JULY 2011System 1

×××××

System 2 System 3 System 417

18

19

20

21

22

23

00

01

0201

02

03

000102

03

04

03

0405

Convection features four quasi-linear systems:

• System 1: 1700 UTC 30 June to 2100 UTC 30 June 2011

• System 2: 2200 UTC 30 June to 0300 UTC 1 July 2011 – evolves into two right-moving supercells (×)

• System 3: 0000 UTC 1 July to 0400 UTC 1 July 2011

• System 4: 0300 UTC 1 July to 0500 UTC 1 July 2011

OUTLINE

• Motivation

• Radar overview



• WRF simulation

FAR-UPSTREAM PRECURSORS

• The evolution of the large-scale flow over North America is often influenced by variability in the large-scale flow over North Pacific

• Variability in the large-scale flow over North Pacific is often influenced by tropical cyclones


Tropical Storm Haima (18–25 June 2011) Tropical Storm Meari (22–27 June 2011)

image source: http://agora.ex.nii.ac.jp/digital-typhoon/index.html.en

• The evolution of the large-scale flow over North America is often influenced by variability in the large-scale flow over North Pacific

• Variability in the large-scale flow over North Pacific is often influenced by tropical cyclones

• What is the influence of tropical storms Haima and Meari on the evolution of the large-scale flow over North America?

Meari Haima

0000 UTC 22 June 2011Precipitable water (mm; shade), 850-hPa rel. vor. (10−4 s−1; white), DT wind speed (m s−1; black), and 700-hPa wind (knots; barbs)


H

M

source: 0.5° NCEP–GFS



H M


0000 UTC 24 June 2011Precipitable water (mm; shade), 850-hPa rel. vor. (10−4 s−1; white), DT wind speed (m s−1; black), 300–200-hPa PV (PVU; thin black), and 250-hPa irrotational wind (m s−1; vectors)


H M


10 m s−1



M


0000 UTC 26 June 2011DT potential temperature (K; shade), DT wind speed (m s−1; black), DT wind (knots; barbs), and 850-hPa rel. vor. (10−4 s−1; white)


M




Shifted domain


0000 UTC 30 June 2011700–500-hPa lapse rate (K km−1; shade), 700–500-hPa wind (knots; barbs), and 200-hPa geo. height (dam; black)


DTθsource: 0.5° NCEP–GFS


40°–50°N

20 June–10 July 2011700–500-hPa lapse rate (K km−1; shade), 250-hPa meridional wind anomaly (every 10 m s−1; red/blue contours), and 250-hPa zonal wind speed (every 5 m s−1 starting at 30; dash)


20 June–10 July 2011700–500-hPa lapse rate (K km−1; shade), 250-hPa meridional wind anomaly (every 10 m s−1; red/blue contours), and 250-hPa zonal wind speed (every 5 m s−1 starting at 30; dash)


40°–50°N

“PRE”

OUTLINE

• Motivation

• Radar overview



• WRF simulation

SYNOPTIC-SCALE AND MESOSCALE ANALYSIS

1800 UTC 30 June 2011250-hPa geo. height (dam; solid) and wind speed (m s−1; shade), and 850-hPa wind (knots; barbs)

source: RUC 20-km

Low-level

jet


1800 UTC 30 June 20111000–500-hPa thick (dam; dash), SLP (hPa; solid), 925-hPa mixing ratio (g kg−1; shade), and 10-m wind (knots; barbs)

source: RUC 20-km


1800 UTC 30 June 2011Most-unstable CAPE (J kg−1; shade) and 0-to-6-km shear (knots; barbs)

source: RUC 20-km


1800 UTC 30 June 2011Manual surface analysis: temperature (°C; red), mixing ratio (g kg−1; green), and SLP (hPa; black)Base reflectivity (dBZ; shaded)

warm

front


1800 UTC 30 June 2011Manual surface analysis: temperature (°C; red), mixing ratio (g kg−1; green), and SLP (hPa; black)Base reflectivity (dBZ; shaded)

W E


1800 UTC 30 June 2011Cross sectional potential temperature (K; gray), mixing ratio (g kg−1; shaded), wind (knots), and horizontal temperature advection (K d−1; dashed every 10 K d−1)

W ELMWIMN MI

6 9 12 15 18 g kg−1

source: RUC 20-km

Pres

sure

(hP

a)


0000 UTC 1 July 20111000–500-hPa thick (dam; dash), SLP (hPa; solid), 925-hPa mixing ratio (g kg−1; shade), and 10-m wind (knots; barbs)

source: RUC 20-km


0000 UTC 1 July 2011Most-unstable CAPE (J kg−1; shade) and 0-to-6-km shear (knots; barbs)

source: RUC 20-km


0000 UTC 1 July 2011University of Wyoming Sounding


0000 UTC 1 July 2011Manual surface analysis: temperature (°C; red), mixing ratio (g kg−1; green), and SLP (hPa; black)Base reflectivity (dBZ; shaded)

warm front


0000 UTC 1 July 2011Manual surface analysis: temperature (°C; red), mixing ratio (g kg−1; green), and SLP (hPa; black)Base reflectivity (dBZ; shaded)

W E


0000 UTC 1 July 2011Cross sectional potential temperature (K; gray), mixing ratio (g kg−1; shaded), wind (knots), and horizontal temperature advection (K d−1; dashed every 10 K d−1)

W ELMWIMN MI

6 9 12 15 18 g kg−1

source: RUC 20-km

Pres

sure

(hP

a)


Pres

sure

(hP

a)

Temperature (°C)

1800 UTC 30 June 2011 0000 UTC 1 July 2011

source: RUC 20-kmRUC soundings


Pres

sure

(hP

a)1800 UTC 30 June 2011

0000 UTC 1 July 2011MAUL?

• Moist-Absolutely Unstable Layer (MAUL) criterion satisfied in RUC sounding at 0000 UTC 1 July 2011 (dewpoint depression <1°C and Δθe/Δz<0)

• MAULs are maintained in regions of strong mesoscale dynamic ascent in the presence of weak convective instability (Bryan and Fritsch 2000)

OUTLINE

• Motivation

• Radar Overview



• WRF simulation

WRF SIMULATION

4-km WRF-ARW simulation initialized at 1200 UTC 30 June 2011

• 4-km WRF-ARW simulation for 1200 UTC 30 Jun–1200 UTC 1 Jul 2011

• Initialized with and without LM (LM and No-LM, respectively)

• Physics: WSM-6; Cumulus: explicit; Surface: thermal diffusion

Initialized with LM Initialized without LM

LM grid points replaced with sub-surface and surface characteristics of Wisconsin grid point

LM (control) No-LM

WRF SIMULATION AND COMPARISON

12-h forecast verifying 0000 UTC 1 July 2011Simulated reflectivity (dBZ; shaded), 2-m pot. temp. (K; contours); and 10-m wind (knots; barbs)

LM (control) No-LM

Observed: NAM 12-h simulated reflectivity: HRRR 12-h simulated reflectivity:

• 30 June–1 July 2011 convective event associated with 24-h precipitation totals >100 mm over western Great Lakes region

• Rossby wave train amplification and dispersion associated with western North Pacific tropical cyclones Meari and Haima produced favorable environmental conditions for convection and heavy precipitation over the western Great Lakes region

• Elevated convection developed along a north-south oriented surface baroclinic zone (warm front) at the nose the low-level jet and in the presence of strong WAA, deep-tropospheric moisture, enhanced midtropospheric static instability, and moist absolute instability

SUMMARY 1

• Convection developed along the shorelines of LM where the LM “cold dome” and strong horizontal temperature gradients may have favored enhanced local ascent and organized convection, respectively

• Influence of LM on convective development was likely secondary to the synoptic and mesoscale environment

• WRF initialized with and without LM at 1200 UTC 30 June 2011 failed to produce the elevated convective event between 1800 UTC and 0600 UTC 1 July 2011

SUMMARY 2

HRES

Annual frequency of warm season 24-h precipitation events >25 mmData source: Unified Precipitation Dataset (UPD) May–October 1984–2003

A Multiscale Analysis of a Heavy Rainfall Event over Lake Michigan

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