H - National Weather Service Southern Region Headquarters - NOAA

Erik Pytlak,
Science and Operations Officer
NOAA/NWS Tucson, AZ

�� Eastern Pacific TCs and monsoon interaction
Indirect TC Impacts on AZ
�� Direct TC hits on AZ
� Unique issues for the SW US
2

� Up‐Gulf p flow common during g
the monsoon, especially in July
� Averages 5‐10 m/s daily
� Cool water pool reinforced by
California Current
� Up‐Gulf oriented thermal and
pressure gradient
� Channeled flow
�� TC passage SW of the Gulf will
enhance the thermal and
pressure gradients
� Direct TC move into the
southern h Gulf lf will ll ddisrupt the h
surface high
L
5
H

Residual PBL
Modified
Gulf of CA PBL
6

� Once ever 2‐3 years (26 since 1965)
� Incoming E Pacific Trough interacts with
the TC
� Deep moisture advected N‐NE
� Mid level center(s) decouple(s) from TC
� Additi Additional l synoptic ti fforcing i mechanism(s) h i ( )
� Subtropical jet enhancement (TC outflow
jet?)
� Mid level warm fronotgenesis, similar to
ET transition
� W Waves of f h heavy rain i over 2‐5 ddays
� Serious Flash Flood threat
9

� Classic indirect impact scenario
� 5610m 500mb low off W Coast
� Pieces broke off parent
circulation
� Three separate waves of
convection
� S Sep 30, O Oct 1, O Oct 2
� $500M damage ($1B in 2008
dollars)
12

Source: HPC
13
Source: WRCC

� Eight g since 1965 9 5( (once every y
5‐6 years)
� Incoming Pacific trough
captures TC and interacts
�� Decaying TD or TS races NN‐
NE (>15kts)
� Beginning ET transition
� Occasional “eye: y (inner rain
band) reintensification
� Major wind damage threat
� Mountains extend above
2000m
� Weak building codes
� Somewhat reduced flash
flood threat
14

� Captured p by y strong, g, ppositively‐tilted y trough g
(BC‐S CA)
� ET transition
� Valley sustained winds 35‐50 mph
� MMountaintop t i t wind i d gusts t 60‐85 6 8 mph h
� 85mph at Ft. Huachuca (Cochise County) Mountain
mesonet Site
� 74mph at Carderoga RAWS (Graham County)
� KTUS: Fastest 2‐min wind: 27kts, 7 ,ppeak ggust 41kts 4
� Lowest pressure measured in AZ: 996.9mb
at Ft. Huachuca/Sierra Vista, AZ)
� Widespread 2‐5” rains SE AZ
16

�� Case of Chen and
Yau (2003)
eyewall
ddestruction, t ti
followed by inner
rain band
redevelopment
� Cloud top temps
cool to ‐72C 72C as PV
transfers from
eye to inner rain
band
Courtesy Scott Bachmeier, CIMSS

�� Simulated
restrengthening ~12hrs
after landfall!
� Pressure drop to 985mb
� Max wind ~80kts at sigma
.865 (~1500m AGL)
� Translates to 45kt
sustained/G60kts
� Chen and Yau 2003

� Captured by moderate, but
weaker‐than‐forecast E
Pacific trough
� Aborted ET transition
� Wid Widespread d 3‐7” ” rain i in i SE CA
� 12.04” at Harquahala Mtn, AZ.
� Highest wind in US: SW UT
(estimates 80‐100mph)
� Wind/ convective bursts on
right‐front quad
� NWP models and NHC called
for recurvature into SE AZ at
H+48‐72hrs
19

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

� Population:
�� 1990: 33.66 66 Million;
� 2008: 6.34 Million (170% increase)
� Rapid grown in both Phoenix/Tucson and mid
elevation cities
� Much larger media markets
� 1990: Phoenix: 17th; Tucson: 82th � 2008: Phoenix: 12th ; Tucson 68th � National AP office in Phoenix
� Electoral Power
�� 1990: 8 Electoral Votes
� 2008: 10 Electoral Votes
� 2012: 12 Electoral Votes?
22

� Western Region g Tropical p Cyclone y Plan
� WFO Tucson Tropical Cyclone Web Page
� WFP Tucson Tropical Cyclone Plan updated
� High g Wind Watch, , Warning, g, and Advisory y Playbook y (elevation ( splits) p )
� Flood/Flash Flood, Local, and CBRFC Collaboration Protocol
� WSR‐88D Tropical Cyclone Plan activated by increments
� PSH software on hot standby
� HPC precip data sharing
� NHC HLT and Media Pool support
� Raising awareness with collaboration partners
� Distant tropical systems can charge up our monsoon
� Indirect impacts/weak and shearing TCs CAN pose a significant flash flood threat
(and can lead to stabilization, warming aloft, and little activity)
� Main threat from a direct hit: flash flooding
� Increase awareness of higher elevation, damaging wind threat
23

WWUS75 KTWC 121533
NPWTWC
URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE TUCSON AZ
833 AM MST TUE SEP 12 2006
...RECENTLY DOWNGRADED TROPICAL STORM PAUL HEADING TOWARD SOUTHERN ARIZONA...
.AT 800 AM MST…TROPICAL STORM PAUL WAS CENTERED NEAR HERMOSILLO SONORA...OR ABOUT
210 MILES SOUTH OF TUCSON…MOVING NORTH AT 18 MPH. MAXIMUM SUSTAINED WINDS HAVE
DECREASED TO 60 MPH AND FURTHER WEAKENING IS EXPECTED. HE WILL CROSS THE
INTERNATIONAL BORDER NEAR NOGALES BY EVENING WITH MAXIMUM SUSTAINED WINDS NEAR
45 MPH MPH. PAUL IS THEN EXPECTED TO WEAKEN INTO A TROPICAL DEPRESSION LATE TONIGHT AS HE
TURNS NORTHEAST TOWARD THE SOUTHERN WHITE MOUNTAINS.
THE STRONGEST WINDS WITH AN INLAND TROPICAL STORM USUALLY CONCENTRATE IN HIGHER
ELEVATIONS. MOUNTAINTOP WINDS IN SANTA CRUZ AND SOUTHERN COCHISE COUNTY WERE
ALREADY NEAR 30 MPH THIS MORNING WITH A FEW GUSTS TO 45 MPH...AND WILL CONTINUE TO
INCREASE THIS AFTERNOON. THERE IS A 20 TO 30 PERCENT CHANCE OF SUSTAINED TROPICAL
STORM FORCE WINDS IN TUCSON THIS AFTERNOON AND TONIGHT.
AZZ019-029-030-032>035-122245-
/O.UPG.KTWC.HW.A.0001.060912T1800Z-060913T1000Z/
/O.NEW.KTWC.HW.W.0002.060912T1800Z-060913T1000Z/
/O.NEW.KTWC.WI.Y.0021.060912T1800Z-060913T1000Z/
NORTHERN GREENLEE COUNTY-SOUTHEAST COUNTY SOUTHEAST PINAL COUNTY COUNTY-
UPPER GILA RIVER VALLEY-TOHONO OODHAM NATION-
TUCSON METRO/MARANA/GREEN VALLEY-SANTA CRUZ COUNTY-COCHISE COUNTY-
833 AM MST TUE SEP 12 2006
...HIGH WIND WARNING IN EFFECT FROM 11 AM THIS MORNING TO 3 AM MST FRIDAY ABOVE 5000
FEET ...
...WIND ADVISORY IN EFFECT FROM 11 AM THIS MORNING TO 3 AM MST FRIDAY BELOW 5000 FEET...
THE NATIONAL WEATHER SERVICE IN TUCSON HAS ISSUED A HIGH WIND WARNING FOR TROPICAL
STORM FORCE WINDS ABOVE 5000 FEET...WHICH IS IN EFFECT FROM 11 AM THIS MORNING TO 3 AM
MST FRIDAY. A WIND ADVISORY HAS ALSO BEEN ISSUED. THIS WIND ADVISORY IS IN EFFECT FROM
11 AM THIS MORNING TO 3 AM MST FRIDAY BELOW 5000 FEET.
MOUNTAINTOP SUSTAINED WINDS WILL INCREASE TO 40 TO 45 MPH THIS AFTERNOON WITH A FEW
GUSTS NEAR 65 MPH. IN THE VALLEYS AND DESERTS...SUSTAINED WINDS WILL INCREASE TO 25 TO
35 MPH WITH A FEW GUSTS TO TROPICAL STORM FORCE. THESE WINDS WILL BE HAZARDOUS FOR...
…
$$