A Multiscale Analysis of the Inland Reintensification of Tropical Cyclone Danny (1997) within an Equatorward

Jet-Entrance Region

Matthew S. Potter, Lance F. Bosart, and Daniel KeyserDepartment of Earth and Atmospheric Sciences

University at Albany, SUNY, Albany, NY

Support Provided By UCAR/NCEP Grant S1071092

NROW-XIIIThursday 3 November 2011

Overview

• Motivation and Objectives • Data and Methodology

• TC Danny (1997) Case Study

• TC Camille (1969) Case Study

• Concluding Remarks

Motivation

• Documentation of inland reintensifying tropical cyclones (TCs) is scarce:

–Bosart and Lackmann (1995): TC David (1979)

–Bassil and Morgan (2006): TC Danny (1997)

– Evans et al. (2011): TC Erin (2007)

Objectives

• Identify inland reintensifying TCs during a 61-yr time period (1950–2010)

• Investigate the physical mechanisms that enable a TC to reintensify inland

Data and Methodology

• Inland Reintensifying TCs (1950–2010)

– TCs which may have reintensified inland (“candidate cases”) were selected subjectively based on information gathered from • NHC best-track data• Archived surface charts from NCDC on microfilm• 2.5° NCEP–NCAR Reanalysis datasets

– Subjective criteria were employed to identify inland reintensifying TCs

– Subjective criteria used to create a list of inland reintensifying TCs

• Minimum central MSLP decreased by 2 hPa and/or maximum sustained wind speed increased by 5 kt in a 6-h time period

• Central circulation (i.e., eye) of the TC remained inland throughout reintensification

• 500-hPa wind speed was less than or equal to 30 kt

• Vertically stacked, warm-core was maintained or enhanced during reintensification

Data and Methodology

• TC Danny Case Study– Used 0.5° Climate Forecast System Reanalysis (CFSR)

datasets to produce maps and cross sections– Employed a potential vorticity perspective to help

elucidate the TC-jet interaction– Used WSR-88D radar data and satellite imagery

from Unidata–Wisconsin data stream to identify changes in precipitation structure

• TC Camille Case Study– Used 2.5° ECMWF 40-yr Reanalysis (ERA-40)

datasets to produce maps and cross sections

Data and Methodology

Inland Reintensifying TCs (1950–2010)

Cindy (1959) Danny (1997)

Cleo (1964) Helene (2000)

Agnes (1972) Allison (2001)

David (1979) Gaston (2004)

Diana (1984) Erin (2007)

• Every TC had an interaction with a upper-level jet except Erin (2007)

•TC Danny had the largest pressure fall (12 hPa) and wind speed increase (10 m s-1) inland compared to other TCs in the climatology

Overview of TC Danny

0000 UTC Locations

1800 UTC 24 July1000 hPa 40 kt

0000 UTC 19 July984 hPa 70 kt

0000 UTC 24 July1012 hPa 20 kt

960 mm of rain fell over Dauphin Island

Track where TC Danny reintensified inland

Overview of TC Danny250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Danny250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Danny250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Danny250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Danny250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Danny250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Danny250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Danny250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Relatively Low Shear Environment Under Anticyclone

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Cross Section and Dynamic Tropopause MapPV (shaded every 1 PVU), θ (solid black, every 5 K), and the wind component normal to the cross section (dotted green every 5 m s-1)

Potential temperature (shaded every 5 K), winds (barbs in kt), and 925–850-hPa layer-averaged relative vorticity (solid black every 0.5 × 10-4 s-1)

Radar and Satellite Imagery

KBMX Base Reflectivity 1813 UTC 22 July

GOES-8 Visible Image 1815 UTC 22 July

KBMX Base Reflectivity 0013 UTC 23 July

GOES-8 Visible Image 2315 UTC 22 July

Radar and Satellite Imagery

KFFC Base Reflectivity 0611 UTC 23 July

GOES-8 Infrared Image 0615 UTC 23 July

Radar and Satellite Imagery

KFFC Base Reflectivity 1218 UTC 23 July

GOES-8 Visible Image 1215 UTC 23 July

Radar and Satellite Imagery

KGSP Base Reflectivity 1823 UTC 23 July

GOES-8 Visible Image 1815 UTC 23 July

Radar and Satellite Imagery

KGSP Base Reflectivity 0015 UTC 24 July

GOES-8 Visible Image 2315 UTC 23 July

Radar and Satellite Imagery

KCAE Base Reflectivity 0617 UTC 24 July

GOES-8 Infrared Image 0615 UTC 24 July

Radar and Satellite Imagery

KAKQ Base Reflectivity 1318 UTC 24 July

GOES-8 Visible Image 1313 UTC 24 July

Radar and Satellite Imagery

KAKQ Base Reflectivity 1814 UTC 24 July

GOES-8 Visible Image 1815 UTC 24 July

Radar and Satellite Imagery

Diabatic Outflow at 1800 UTC 24 July250-hPa wind speed (color shading in kt), 250-hPa potential vorticity (solid gray every 1 PVU), 250-hPa relative humidity (gray shading in %), 600–400-hPa layer-averaged ω (red every 4 × 10-3 hPa s-1, negative values only), 300–200 hPa layer-averaged irrotational wind (arrows, m s-1)

Diabatic outflow from convection around TC Danny strengthens jet

Ageostrophic Circulation and FrontogenesisFrontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

5 cm/s

Ageostrophic Circulation and Frontogenesis

5 cm/s

Frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

Ageostrophic Circulation and Frontogenesis

5 cm/s

Frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

Ageostrophic Circulation and Frontogenesis

5 cm/s

Frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

Ageostrophic Circulation and Frontogenesis

5 cm/s

Frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

Ageostrophic Circulation and Frontogenesis

5 cm/s

Frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

Ageostrophic Circulation and Frontogenesis

5 cm/s

Frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

Frontogenesis

Ageostrophic Circulation and Frontogenesis

5 cm/s

Frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

Frontogenesis

Ageostrophic Circulation and Frontogenesis

5 cm/s

Frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every --5 × 10-3 hPa s-1), wind component normal to the cross section (solid brown, m s-1), and the ageostrophic wind component tangential to the cross section (arrows, m s-1)

Danny Remarks• Danny Case Study– The inland reintensification of TC Danny can be

attributed to:(1) Frontogenesis along the lower-tropospheric baroclinic

zone and the associated tropospheric-deep ascent beneath the equatorward entrance region of the upper-level jet

(2) Deep convection that provided a source of diabatic heating and reinforced the ascent near the storm center

(3) Upper-tropospheric PV reduction north of the storm center that strengthened the meridional PV gradient and the associated jet

(4) Lower-tropospheric vorticity growth in an environment that favored enhanced ascent near the storm center

Overview of TC Camille

0000 UTC Locations

0000 UTC 18 August909 hPa 165 kt

0000 UTC 20 August1005 hPa 25 kt

Severe Inland Flooding (153 fatalities)

690 mm of rain fell over West Nelson County

Overview of TC Camille250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Camille250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Overview of TC Camille250-hPa wind speed (shaded, m s-1), 1000–500-hPa thickness (dashed red, dam), and MSLP (solid black, hPa)

Frontogenesis and Moisture 925-hPa frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 1 K), mixing ratio (solid red every 1 g kg-1), and winds (barbs, m s-1)

Frontogenesis and Moisture 925-hPa frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 1 K), mixing ratio (solid red every 1 g kg-1), and winds (barbs, m s-1)

Frontogenesis and Moisture

Region of worst flooding

925-hPa frontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 1 K), mixing ratio (solid red every 1 g kg-1), and winds (barbs ,m s-1)

Ageostrophic Circulation and FrontogenesisFrontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every 0.5 × 10-3 hPa s-1, negative values only), and the ageostrophic wind component tangential to the cross section (m s-1)

5 cm/s

Ageostrophic Circulation and FrontogenesisFrontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every 0.5 × 10-3 hPa s-1, negative values only), and the ageostrophic wind component tangential to the cross section (m s-1)

5 cm/s

Frontogenesis

Ageostrophic Circulation and FrontogenesisFrontogenesis (shaded in K (100 km)-1 (3 h)-1), θ (solid black every 5 K), ω (dotted red every 0.5 × 10-3 hPa s-1, negative values only), and the ageostrophic wind component tangential to the cross section (m s-1)

5 cm/s

Frontogenesis

Camille Remarks

• Camille Case Study– The inland flooding associated with TC

Camille can be attributed to:(1) Moist, southerly flow that focused moisture

along a lower-tropospheric frontogenetical baroclinic zone over an area of complex terrain

(2) Tropospheric-deep ascent beneath the equatorward entrance region of an upper-level jet

Concluding Remarks• Differences between TC Camille and TC Danny– Inland reintensification only occurred with TC Danny– Inland flooding associated with TC Camille occurred in a

more favorable environment

• Similarities between TC Camille and TC Danny– Interaction with an equatorward entrance region of an

upper-level jet– Frontogenesis along a lower-tropospheric baroclinic zone