What have we learned What have we learned from NAME?from NAME?

Erik PytlakNOAA/NWS Tucson, AZ

NORTH AMERICAN MONSOON EXPERIMENT (NAME)NORTH AMERICAN MONSOON EXPERIMENT (NAME)

YEAR (2000+) 00 01 02 03 04 05 06 07 08

Planning --------------|

Preparations ---------------|

Data Collection - - - - - - --------|

Principal Research ---------------------------------|

Data Management -----------------------------------------|

HYPOTHESIS:HYPOTHESIS:The NAMS provides a physical basis for determining the degreeof predictability of warm seasonprecipitation over the region.

OBJECTIVES:OBJECTIVES:Better understanding andsimulation of:

• warm season convective processes in complex terrain (TIER I);

• intraseasonal variability of the monsoon (TIER II);

• response to oceanic and continental boundary conditions (TIER III);

• monsoon evolution and variability (TIER I, II, III).

Low-level (925 mb) winds and observed precipitation

WHAT WAS THE NAME 2004 WHAT WAS THE NAME 2004 FIELD CAMPAIGN?FIELD CAMPAIGN?

The NAME 2004 Field Campaign was an unprecedented opportunity to gather extensive atmospheric, oceanic, and land-surface observations in the core region of the North American Monsoon over NW Mexico, SW United States, and adjacent oceanic areas.

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What What reallyreally is The Monsoon? is The Monsoon?

• A A seasonalseasonal change in upper level change in upper level winds from the polar westerlies to winds from the polar westerlies to tropical easterliestropical easterlies

• Change from very dry west winds Change from very dry west winds aloft to moist winds aloft from the aloft to moist winds aloft from the east or southeasteast or southeast

• North American Monsoon is just North American Monsoon is just one of severalone of several

– Indian MonsoonIndian Monsoon

– Asian MonsoonAsian Monsoon

– Australian MonsoonAustralian Monsoon

– African MonsoonAfrican Monsoon

– South American MonsoonSouth American Monsoon

• An individual thunderstorm is An individual thunderstorm is NOT a “monsoon”NOT a “monsoon”

• The monsoon IS a large scale The monsoon IS a large scale flow patternflow pattern

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The North American MonsoonThe North American Monsoon

• 500 mb mean flow 500 mb mean flow

Notice the positioning of the subtropical (cT) upper level high.

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Four Different MonsoonsFour Different Monsoons

• Mean subtropical (cT) high position generally reveals what the monsoon Mean subtropical (cT) high position generally reveals what the monsoon looked like in any given summerlooked like in any given summer

2004 2006

2008 2009

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Positioning of the high determines Positioning of the high determines general severe weather patterngeneral severe weather pattern

The hotly? debated patternThe hotly? debated pattern

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Monsoon Moisture SourcesMonsoon Moisture Sources

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Sierra Madres…Sierra Madres…

Subtropical Seasonal Rain Forest =Subtropical Seasonal Rain Forest =Lots of Moisture!!!Lots of Moisture!!!

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Gulf of California LLJGulf of California LLJ

• Up-Gulf flow common Up-Gulf flow common during the monsoon, during the monsoon, especially in Julyespecially in July

– Averages 5-10 m/s dailyAverages 5-10 m/s daily

– Cool water pool Cool water pool reinforced by California reinforced by California CurrentCurrent

– Up-Gulf oriented thermal Up-Gulf oriented thermal and pressure gradientand pressure gradient

– Channeled flowChanneled flow

• TC passage SW of the Gulf TC passage SW of the Gulf will enhance the thermal will enhance the thermal and pressure gradientsand pressure gradients

• Direct TC move into the Direct TC move into the southern Gulf will disrupt southern Gulf will disrupt the surface highthe surface high

H

L

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Gulf Surge during NAME 2004Gulf Surge during NAME 2004

Dewpoint = 55F

Dewpoint = 75-82F!!!

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Shallow/Strong Gulf Surge Shallow/Strong Gulf Surge Impact at KTUSImpact at KTUS

Residual PBL

ModifiedGulf of CA PBL

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TC-initiated surges during TC-initiated surges during NAMENAME

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““The Dewpoint Rule”The Dewpoint Rule”No Longer UsedNo Longer Used

• Ancient monsoon monitoring toolAncient monsoon monitoring tool

– Started in Phoenix in the 1950sStarted in Phoenix in the 1950s

– Done when weather radar (in AZ, Done when weather radar (in AZ, anyway) and weather satellites didn’t anyway) and weather satellites didn’t existexist

– PHX dewpoint was used for the entire PHX dewpoint was used for the entire statestate

– Adopted for Tucson (due to our higher Adopted for Tucson (due to our higher elevation in 1997)elevation in 1997)

• Tucson dewpoint had to average 54 Tucson dewpoint had to average 54 degrees each day for three consecutive degrees each day for three consecutive daysdays

• Easy to trackEasy to track

• VERY misleadingVERY misleading

• NWS now uses a fixed monsoon NWS now uses a fixed monsoon season : June 15-September 30season : June 15-September 30

http://www.wrh.noaa.gov/twc/monsoon/dewpoint_tracker.php

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Upper Tropospheric LowsUpper Tropospheric Lows

• 12-20 of them a year affect 12-20 of them a year affect North American MonsoonNorth American Monsoon

– More (less) of them during La More (less) of them during La Niña (El Niño) summers Niña (El Niño) summers

• Subtropical systemsSubtropical systems

• Mid June - early SeptemberMid June - early September

• Move east-to-westMove east-to-west

• Relatively cold/sinking Relatively cold/sinking centerscenters

• Can cause widespread Can cause widespread severe weather and flash severe weather and flash floodingflooding

• Difficult to track at timesDifficult to track at times

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Original Conceptual ModelsOriginal Conceptual Models

Kelley and Mock 1982 Moore, Gall and Adang 1989

Whitfield and Lyons 1992

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NAME Cross SectionNAME Cross Section7/13/047/13/04

1°x1° res. Courtesy Paul Cieleski, Colorado State University

C

Conceptual Model: Upper Tropospheric

Lows

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……especially when there’s several of themespecially when there’s several of them

Ongoing Research: PV AnomaliesOngoing Research: PV Anomalies

PV Trough PV Tail PV Fracture

=350 K

Lower

=350 KLo

wer

=350 K

Lower

2 x Width > Length 2 x Width < Length Circular or Linear

SUNY Albany: Bosart, Matusiak, Sikup, Melino

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Tropical Cyclones and the MonsoonTropical Cyclones and the Monsoon

• Modulate monsoon-related Modulate monsoon-related convectionconvection

– Gulf SurgesGulf Surges

– Moisture injection into the SMOMoisture injection into the SMO

– Do not have to recurve Do not have to recurve

• Those that do follow a general Those that do follow a general recurvature patternrecurvature pattern

– Interaction with the East Pacific Interaction with the East Pacific trough is criticaltrough is critical

• ENSO conditions:ENSO conditions:

– Warmer SSTs = more TCsWarmer SSTs = more TCs

– Cooler SSTs = stronger E Pac Cooler SSTs = stronger E Pac trough/higher recurvature trough/higher recurvature chancechance

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Direct Hit and Indirect Impact Direct Hit and Indirect Impact Track DensityTrack Density

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Octave: Sep 28-Oct 2, 1983Octave: Sep 28-Oct 2, 1983

• Classic indirect impact Classic indirect impact scenarioscenario

• Pieces broke off parent Pieces broke off parent circulationcirculation

• Three separate waves Three separate waves of convectionof convection

– Sep 30, Oct 1, Oct 2Sep 30, Oct 1, Oct 2

• $500M damage ($1B in $500M damage ($1B in 2008 dollars)2008 dollars)

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AZ Tropical CyclonesAZ Tropical CyclonesDirect HitsDirect Hits

• Eight since 1965 (once every 5-8 Eight since 1965 (once every 5-8 years)years)

• Incoming Pacific trough captures Incoming Pacific trough captures TC and interactsTC and interacts

• Decaying TD or TS races N-NEDecaying TD or TS races N-NE

• Unusually large TC, or enlarging Unusually large TC, or enlarging TCTC

• Begin ET transitionBegin ET transition

• Major wind damage threatMajor wind damage threat

– Mountains extend above 2000mMountains extend above 2000m

– Weak building codesWeak building codes

• Somewhat reduced flash flood Somewhat reduced flash flood threatthreat

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Lester: Aug 23-24, 1992Lester: Aug 23-24, 1992

• Captured by strong, positively-tilted Captured by strong, positively-tilted trough (BC-S CA)trough (BC-S CA)

• ET transitionET transition

• Valley sustained winds 35-50 mphValley sustained winds 35-50 mph

• Mountaintop wind gusts 60-85 mph Mountaintop wind gusts 60-85 mph

– 85mph at Ft. Huachuca (Cochise County) 85mph at Ft. Huachuca (Cochise County) Mountain mesonet SiteMountain mesonet Site

– 74mph at Carderoga RAWS (Graham County)74mph at Carderoga RAWS (Graham County)

– KTUS: Fastest 2-min wind: 27kts, peak gust 41ktsKTUS: Fastest 2-min wind: 27kts, peak gust 41kts

• Lowest pressure measured in AZ: Lowest pressure measured in AZ: 996.9mb at Ft. Huachuca/Sierra Vista, 996.9mb at Ft. Huachuca/Sierra Vista, AZ)AZ)

• Widespread 2-5” rains SE AZWidespread 2-5” rains SE AZ

Lester ET TransitionLester ET Transition

• Case of Chen Case of Chen and Yau (2003) and Yau (2003) eyewall eyewall destruction, destruction, followed by followed by inner rain band inner rain band redevelopmentredevelopment

• Cloud top temps Cloud top temps cool to -72°C as cool to -72°C as PV transfers PV transfers from eye to from eye to inner rain bandinner rain band

Courtesy Scott Bachmeier, CIMSS

Lester: MM5 SimulationLester: MM5 Simulation

• Simulated Simulated restrengthening ~12hrs restrengthening ~12hrs after landfall!after landfall!

– Pressure drop to 985mbPressure drop to 985mb

– Max wind ~80kts at Max wind ~80kts at sigma .865 (~1500m AGL)sigma .865 (~1500m AGL)

• Translates to 45kt Translates to 45kt sustained/G60ktssustained/G60kts

– Chen and Yau 2003Chen and Yau 2003

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Nora, Sep 25-26, 1997Nora, Sep 25-26, 1997

• Captured by moderate, but Captured by moderate, but weaker-than-forecast E Pacific weaker-than-forecast E Pacific troughtrough

• Aborted ET transitionAborted ET transition

– Widespread 3-7” rain in SE CAWidespread 3-7” rain in SE CA

– 12.04” at Harquahala Mtn, AZ.12.04” at Harquahala Mtn, AZ.

– Highest wind in US: SW UT Highest wind in US: SW UT (estimates 80-100mph))(estimates 80-100mph))

– Wind/ convective bursts on Wind/ convective bursts on right-front quadright-front quad

• NWP models and NHC called NWP models and NHC called for recurvature into SE AZ at for recurvature into SE AZ at H+48-72hrsH+48-72hrs

Nora, Sep 25-26, 1997Nora, Sep 25-26, 1997

92kts at 5000 ft(reduces to ~50G65kt)

Educating the Public:Educating the Public:Monsoon Tracking PageMonsoon Tracking Page

• Dew point graphsDew point graphs

• Winds for 700, 500 and 300 mbWinds for 700, 500 and 300 mb

• Heights for 500 mbHeights for 500 mb

• Satellite-derived vegetation indexSatellite-derived vegetation index

• Satellite water vapor imagerySatellite water vapor imagery

• Radar precipitation estimates for 1, 3, 6, 12 Radar precipitation estimates for 1, 3, 6, 12 and 24 hoursand 24 hours

• Upper air plotsUpper air plots

• Links to Maricopa and Pima county rainfall Links to Maricopa and Pima county rainfall datadata

• Extensive safety informationExtensive safety information

• Extensive reference listExtensive reference list

• Yes, you can still track dewpointYes, you can still track dewpoint

• Companion Tropical Cyclone pageCompanion Tropical Cyclone page

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Parting thoughts:Parting thoughts:

http://www.eol.ucar.edu/projects/namehttp://www.wrh.noaa.gov/twc/monsoon/monsoon_tracker.php