The Impact of a Prominent Rain Shadow on Flooding in California's Santa Cruz Mountains: A CALJET Case Study

Abstract Data from the California Land-Falling Jets Experiment (CALJET) are used to explore the causes of variations in flood severity in adjacent coastal watersheds within the Santa Cruz Mountains on 2–3 February 1998. While Pescadero Creek (rural) experienced its flood of record, the adjacent San Lorenzo Creek (heavily populated), attained only its fourth-highest flow. This difference resulted from conditions present while the warm sector of the storm, with its associated low-level jet, high moisture content, and weak static stability, was overhead. Rainfall in the warm sector was dominated by orographic forcing. While the wind speed strongly modulated rain rates on windward slopes, the wind direction positioned the edge of a rain shadow cast by the Santa Lucia Mountains partially over the San Lorenzo basin, thus protecting the city of Santa Cruz from a more severe flood. Roughly 26% ± 9% of the streamflow at flood peak on Pescadero Creek resulted from the warm-sector rainfall. Without this rainfall, th...

[1]  F. Martin Ralph,et al.  Influence of ENSO on Flood Frequency along the California Coast , 2004 .

[2]  F. Martin Ralph,et al.  Coastal Orographic Rainfall Processes Observed by Radar during the California Land-Falling Jets Experiment , 2003 .

[3]  Jerome P. Charba,et al.  Comparative Verification of Recent Quantitative Precipitation Forecasts in the National Weather Service: A Simple Approach for Scoring Forecast Accuracy , 2003 .

[4]  P. Neiman,et al.  The statistical relationship between upslope flow and rainfall in California's coastal mountains: Observations during CALJET , 2002 .

[5]  W. Nuss,et al.  Mesoscale predictability under various synoptic regimes , 2001 .

[6]  Jeff S. Waldstreicher,et al.  Observations of Mountain Wave–Induced Precipitation Shadows over Northeast Pennsylvania , 2001 .

[7]  C. Mass,et al.  An Observational and Numerical Study of an Intense Landfalling Cold Front along the Northwest Coast of the United States during COAST IOP 2 , 2001 .

[8]  B. Smull,et al.  Airborne Doppler Observations of a Landfalling Cold Front Upstream of Steep Coastal Orography , 2000 .

[9]  Brian A. Colle,et al.  The Limitations of the WSR-88D Radar Network for Quantitative Precipitation Measurement over the Coastal Western United States , 1999 .

[10]  Daniel R. Cayan,et al.  ENSO and Hydrologic Extremes in the Western United States , 1999 .

[11]  Robert E. Livezey,et al.  NCEP Forecasts of the El Niño of 1997–98 and Its U.S. Impacts , 1999 .

[12]  Michael D. Dettinger,et al.  North–South Precipitation Patterns in Western North America on Interannual-to-Decadal Timescales , 1998 .

[13]  K. Wolter,et al.  Measuring the strength of ENSO events: How does 1997/98 rank? , 1998 .

[14]  Dong-Jun Seo,et al.  The WSR-88D rainfall algorithm , 1998 .

[15]  R. E. Livezey,et al.  Teleconnective response of the Pacific-North American region atmosphere to large central equatorial Pacific SST anomalies , 1997 .

[16]  J. Doyle.  The Influence of Mesoscale Orography on a Coastal Jet and Rainband , 1997 .

[17]  Steven J. Nieman,et al.  Fully automated cloud-drift winds in NESDIS operations , 1997 .

[18]  F. Wentz.  A well‐calibrated ocean algorithm for special sensor microwave / imager , 1997 .

[19]  Steven J. Nieman,et al.  Upper-Tropospheric Winds Derived from Geostationary Satellite Water Vapor Observations , 1997 .

[20]  D. Jorgensen,et al.  Multi-beam techniques for deriving wind fields from airborne doppler radars , 1996 .

[21]  N. Bond,et al.  Observations and Scale Analysis of Coastal Wind Jets , 1995 .

[22]  J. Dracup,et al.  The influences of Type 1 El Nino and La Nina events on streamflows in the Pacific Southwest of the United States , 1994 .

[23]  D. B. Wuertz,et al.  Quality Controls for Profiler Measurements of Winds and RASS Temperatures , 1993 .

[24]  David A. Imy,et al.  A Description of the Initial Set of Analysis Products Available from the NEXRAD WSR-88D System , 1993 .

[25]  Donald W. Burgess,et al.  Recording, Archiving, and Using WSR-88D Data , 1993 .

[26]  D. Parsons.  An Explanation for Intense Frontal Updrafts and Narrow Cold-Frontal Rainbands , 1992 .

[27]  Toby N. Carlson,et al.  Mid-Latitude Weather Systems , 1991 .

[28]  S. Nicholson,et al.  The Relationship between California Rainfall and ENSO Events , 1989 .

[29]  R. Rauber,et al.  The Characteristics and Evolution of Supercooled Water in Wintertime Storms over the Sierra Nevada: A Summary of Microwave Radiometric Measurements Taken during the Sierra Cooperative Pilot Project , 1988 .

[30]  Warner L. Ecklund,et al.  A UHF Wind Profiler for the Boundary Layer: Brief Description and Initial Results , 1988 .

[31]  Arunas P. Kuciauskas,et al.  Remote and In Situ Observations of Sierra Nevada Winter Mountain Clouds: Relationships between Mesoscale Structure, Precipitation and Liquid Water. , 1988 .

[32]  David F. Jorgensen.  Mesoscale and Convective-Scale Characteristics of Mature Hurricanes. Part I: General Observations by Research Aircraft , 1984 .

[33]  E. Rasmusson,et al.  Meteorological Aspects of the El Ni�o/Southern Oscillation , 1983, Science.

[34]  F. Hill.  The use of average annual rainfall to derive estimates of orographic enhancement of frontal rain over England and Wales for different wind directions , 1983 .

[35]  T. Parish.  Barrier Winds Along the Sierra Nevada Mountains , 1982 .

[36]  Robert M. Rabin,et al.  Subsynoptic-Scale Vertical Wind Revealed by Dual Doppler-Radar and VAD Analysis , 1980 .

[37]  K. Browning,et al.  Structure and mechanism of precipitation and the effect of orography in a wintertime warm sector , 1974 .

[38]  K. A. Browning,et al.  The Determination of Kinematic Properties of a Wind Field Using Doppler Radar , 1968 .

[39]  Brian A. Colle,et al.  The Limitations of the WSR-88 D Radar Network for Quantitative Precipitation Measurement over the Coastal Western United States , 1999 .

[40]  Clifford F. Mass,et al.  Local and remote effects of mountains on weather: Research needs and opportunities , 1997 .

[41]  Robert H. Webb,et al.  El Nino/Southern Oscillation and streamflow in the western United States , 1993 .

[42]  J. Marwitz.  Deep Orographic Storms over the Sierra Nevada. Part I: Thermodynamic and Kinematic Structure , 1987 .

[43]  E. Rasmusson,et al.  El Nio and Variations in Climate , 1985 .

[44]  K. Browning,et al.  Persistence and orographic modulation of mesoscale precipitation areas in a potentially unstable warm sector , 1979 .

[45]  Ronald B. Smith.  The Influence of Mountains on the Atmosphere , 1979 .

[46]  J. O. Rhea.  Orographic Precipitation Model for Hydrometeorological Use. , 1977 .