Gulf Surges, the Diurnal Cycle, and Convective Outflows as Revealed by the NCAR ISSs in NAMERichard H. Johnson, Peter J. Rogers, Paul E. Ciesielski, Brian D. McNoldy, and Richard K. Taft

Colorado State University

Acknowledgments: NSF, NOAA, NCAR ATD staff, and numerous students who worked at ISS sites

NCAR Integrated Sounding System (ISS)• Vaisala GPS sounding system• Enhanced surface observing

station• 915 MHz Doppler clear-air wind

profiling radar• Radio Acoustic Sounding System

(RASS)

• 3 ISSs used in NAME

• 1 GLASS sounding system ISS Trailer, Los Mochis

NAME SOUNDING NETWORK

PUERTO PEÑASCO

BAHIA KINO

LOS MOCHIS

LORETO

3 ISSs 1 GLASS

N GULFS1

(IOP2)

S2 (IOP3)

2004

May June July Aug Sep

PRECIPITABLE WATER (105-115°W)

(NCEP Operational Analysis)

HU

RR

JA

VIER

HU

RR

HO

WA

RD

TS B

LAS

(IOP10)

TS A

GA

THA

HU

RR

CEL

IA

HU

RR

DA

RB

Y

HU

RR

FR

AN

KTS

GEO

RG

ETTE

HU

RR

ISIS

Moisture surges

and tropical waves,

cyclones

BLAS

DARBY

FRANK

GEORGETTE

HOWARD

ISIS

JAVIER

CEN

TRA

L G

ULF

700-hPa V WIND (15-25°N)

Easterly Waves During NAME EOP

May

Jun

Jul

Aug

Sep

2004

CELIA

L

TROPICAL STORM BLAS

YUMA

●`

●MAZATLAN

Heat Low

1004

TS BLAS

QuikSCAT Winds

HURR JAVIER

HURR HOWARD

TS GEORGETTE

N GULF

S GULF

13 JULY

HURR DARBY?

HURR FRANK

V

BLAS

13 July 20040024-0824Z

LOS MOCHIS

BAHIA KINO

PUERTO PEÑASCO

●LOS MOCHIS ISS

MIDNIGHT NOON

SURGE

GUST FRONT

4-hPa rise

00 UTC

05 10 15 20

GUST FRONT

SURGE PEAK

km

● BAHIA KINO ISS

7 hPa rise, but over longer period

SURGE

3-hPa rise

NOONMIDNIGHT

PUERTO PEÑASCO ISS●

SURGE

GUST FRONTS

3.5-hPa rise

NOONMIDNIGHT

km

surge

(RASS shut down at night due to noise

impact on local populace)

4-hPa additional rise

SURGE CONTINUES NEXT DAY, PEAKING AT NIGHT

NOONMIDNIGHT

NOONMIDNIGHT

PRESSURE MAXIMUM, 8 hPa INCREASE OVER 2 DAYS

Puerto Peñasco Bahia Kino Los Mochis

Pressure rise signature progresses up the Gulf (8-10 h from Los Mochis to Puerto Peñasco)

20-25 m s-1 propagation speed!

Pressure signature and speed characteristic of an internal bore or mixed Kelvin wave–bore (e.g., Ralph et al. 2000)

7-8 hPa rise

Altair12/20 – 13/04Z

Puerto Peñasco13/12 – 13/18Z

●

● ●

●●

PEAK WINDS NEAR THE SURFACE IN

THE NORTH

…PEAK WINDS ELEVATED IN THE SOUTH

GULF-// WINDS

●●

● ●●

COOLING ASSOCIATED

WITH SURGES…

• PRINCIPALLY CONFINED BELOW 700 hPa• LASTS FOR 3-4 DAYS• ELEVATED IN S FOR FIRST SURGE

T

Rain moved northward

along coastal

plain and into AZ with

surge

24-h totals, 12-14 July

UTC NOONMIDNIGHT

EOP-MEAN LOW-LEVEL

WIND DIURNAL CYCLE

(7 JUL – 14 AUG)

PP

BK

LM

Strong low-level jet at PP, much weaker at BK, absent at LM (Douglas 1995)

Sea breezes

Puerto Penasco

Bahia Kino

Los Mochis Weak land

breezes, nocturnal offshore convection near S-Pol

S-POL RADAR

3 Aug2004

1000-1330UTC

NOAA-ETL PROFILER

Summary and Conclusions• ISSs successfully documented many aspects of NAM along Gulf of California, including characteristics of surges

• July 13 surge associated with TS BLAS, preceded by downdraft outflows from SMO convection

• Peak surge winds on 13 July descend from 1.2 km AGL at LM and BK, to near 700 m at PP, maximum wind 20 m s-1 at Puerto Penasco; convective outflows are shallower (peak winds near 300 m)

• Pressure rises 3-4 hPa over 8-10 h period of surge, followed by additional 4 hPa rise over next 1-2 days (2-3°C surface temperature drop); initial P-rise signal moved rapidly up Gulf (20-25 m s-1) internal bore, mixed Kelvin wave-bore? (awaiting more data)

Summary and Conclusions (cont)

• Surge on 13 July led to increased TPW and rainfall over southwestern US

• Diurnal cycle of PBL winds varies from south to north; prominent nocturnal LLJ in north, absent in south; prominent afternoon sea breezes at BK and LM; weak land breezes at BK and LM, coastal offshore convection near S-Pol

• Results are preliminary; further analysis awaits additional surface, pibal, and sounding data

(Ralph et al. 2000)

(Ralph et al. 2000)(Nuss et al. 2000)