• Adams, J. L., , and D. J. Stensrud, 2007: Impact of tropical easterly waves on the North American monsoon. J. Climate, 20 , 12191238.

  • Berry, G., , and C. Thorncroft, 2005: Case study of an intense African easterly wave. Mon. Wea. Rev., 133 , 752766.

  • Berry, G., , C. Thorncroft, , and T. Hewson, 2007: African easterly waves during 2004—Analysis using objective techniques. Mon. Wea. Rev., 135 , 12511267.

    • Search Google Scholar
    • Export Citation
  • Bordoni, S., , and B. Stevens, 2006: Principal component analysis of the summertime winds over the Gulf of California: A gulf surge index. Mon. Wea. Rev., 134 , 33953414.

    • Search Google Scholar
    • Export Citation
  • Bordoni, S., , P. E. Ciesielski, , R. H. Johnson, , B. D. McNoldy, , and B. Stevens, 2004: The low-level circulation of the North American monsoon as revealed by QuikSCAT. Geophys. Res. Lett., 31 , L10109. doi:10.1029/2004GL020009.

    • Search Google Scholar
    • Export Citation
  • Brenner, I. S., 1974: A surge of maritime tropical air—Gulf of California to the southwestern United States. Mon. Wea. Rev., 102 , 375389.

    • Search Google Scholar
    • Export Citation
  • Burpee, R. W., 1972: The origin and structure of easterly waves in the lower troposphere of North Africa. J. Atmos. Sci., 29 , 7790.

  • Burpee, R. W., 1974: Characteristics of North African easterly waves during the summers of 1968 and 1969. J. Atmos. Sci., 31 , 15561570.

    • Search Google Scholar
    • Export Citation
  • Charba, J. P., , A. W. Harrell III, , and A. C. Lackner III, 1992: A monthly precipitation amount climatology derived from published atlas maps: Development of a digital database. TDL Office Note 92-7, 20 pp. [Available from TDL Office, NOAA, U.S. Department of Commerce, 1325 East–West Highway, Silver Spring, MD 20910.].

    • Search Google Scholar
    • Export Citation
  • Chen, T. C., 2006: Characteristics of African easterly waves depicted by ECMWF reanalyses for 1991–2000. Mon. Wea. Rev., 134 , 35393566.

    • Search Google Scholar
    • Export Citation
  • Chen, W. Y., 1982: Fluctuations in Northern Hemisphere 700 mb height field associated with the Southern Oscillation. Mon. Wea. Rev., 110 , 808823.

    • Search Google Scholar
    • Export Citation
  • Cressman, G. P., 1959: An operational objective analysis system. Mon. Wea. Rev., 87 , 367374.

  • Douglas, A. V., , and P. J. Englehart, 2007: A climatological perspective of transient synoptic features during NAME 2004. J. Climate, 20 , 19471954.

    • Search Google Scholar
    • Export Citation
  • Douglas, M. W., 1995: The summertime low-level jet over the Gulf of California. Mon. Wea. Rev., 123 , 23342347.

  • Douglas, M. W., , and J. C. Leal, 2003: Summertime surges over the Gulf of California: Aspects of their climatology, mean structure, and evolution from radiosonde, NCEP reanalysis, and rainfall data. Wea. Forecasting, 18 , 5574.

    • Search Google Scholar
    • Export Citation
  • Douglas, M. W., , R. A. Maddox, , K. Howard, , and S. Reyes, 1993: The Mexican monsoon. J. Climate, 6 , 16651677.

  • Douglas, M. W., , A. Valdez-Manzanilla, , and R. Garcia Cueto, 1998: Diurnal variation and horizontal extent of the low-level jet over the northern Gulf of California. Mon. Wea. Rev., 126 , 20172025.

    • Search Google Scholar
    • Export Citation
  • Farfan, L. M., , and J. A. Zehnder, 2001: An analysis of the landfall of hurricane Nora (1997). Mon. Wea. Rev., 129 , 20732088.

  • Fink, A. H., , D. G. Vincent, , P. M. Reiner, , and P. Speth, 2004: Mean state and wave disturbances during phase I, II, and III of GATE based on ERA-40. Mon. Wea. Rev., 132 , 16611683.

    • Search Google Scholar
    • Export Citation
  • Fuller, R. D., , and D. J. Stensrud, 2000: The relationship between tropical easterly waves and surges over the Gulf of California during the North American monsoon. Mon. Wea. Rev., 128 , 29832989.

    • Search Google Scholar
    • Export Citation
  • Fyfe, J. C., 1999: Climate simulations of African easterly waves. J. Climate, 12 , 17471769.

  • Glahn, H. R., , T. L. Chambers, , W. S. Richardson, , and H. P. Perrotti, 1985: Objective map analysis for the local AFOS MOS Program. NOAA Tech. Memo. NWS TDL 75, 34 pp. [Available from TDL Office, NOAA, U.S. Department of Commerce, 1325 East–West Highway, Silver Spring, MD 20910.].

    • Search Google Scholar
    • Export Citation
  • Gutzler, D. S., 2004: An index of interannual precipitation variability in the core of the North American monsoon region. J. Climate, 17 , 44734480.

    • Search Google Scholar
    • Export Citation
  • Hales, J. E., 1972: Surges of maritime tropical air northward over the Gulf of California. Mon. Wea. Rev., 100 , 298306.

  • Hales, J. E., 1974: Southwestern United States summer monsoon source—Gulf of Mexico or Pacific Ocean? J. Appl. Meteor., 13 , 331342.

    • Search Google Scholar
    • Export Citation
  • Higgins, R. W., , and W. Shi, 2000: Dominant factors responsible for interannual variability of the summer monsoon in the southwestern United States. J. Climate, 13 , 759776.

    • Search Google Scholar
    • Export Citation
  • Higgins, R. W., , and W. Shi, 2005: Relationships between Gulf of California moisture surges and tropical cyclones in the eastern Pacific basin. J. Climate, 18 , 46014620.

    • Search Google Scholar
    • Export Citation
  • Higgins, R. W., , Y. Yao, , and X. L. Wang, 1997: Influence of the North American monsoon system on the U.S. summer precipitation regime. J. Climate, 10 , 26002622.

    • Search Google Scholar
    • Export Citation
  • Higgins, R. W., , K. C. Mo, , and Y. Yao, 1998: Interannual variability of the U.S. summer precipitation regime with emphasis on the southwestern monsoon. J. Climate, 11 , 25822606.

    • Search Google Scholar
    • Export Citation
  • Higgins, R. W., , Y. Chen, , and A. V. Douglas, 1999: Interannual variability of the North American warm season precipitation regime. J. Climate, 12 , 653680.

    • Search Google Scholar
    • Export Citation
  • Higgins, R. W., , W. Shi, , and C. Hain, 2004: Relationships between Gulf of California moisture surges and precipitation in the southwestern United States. J. Climate, 17 , 29832997.

    • Search Google Scholar
    • Export Citation
  • Hu, Q., , and S. Feng, 2002: Interannual rainfall variations in the North American summer monsoon region: 1900–98. J. Climate, 15 , 11891202.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Livezey, R. E., , and W. Chen, 1983: Statistical field significance and its determination by Monte Carlo techniques. Mon. Wea. Rev., 111 , 4659.

    • Search Google Scholar
    • Export Citation
  • McCollum, D. M., , R. A. Maddox, , and K. W. Howard, 1995: Case study of a severe mesoscale convective system in central Arizona. Wea. Forecasting, 10 , 643665.

    • Search Google Scholar
    • Export Citation
  • Mo, K. C., , and E. H. Berbery, 2004: Low-level jets and the summer precipitation regimes over North America. J. Geophys. Res., 109 , D06117. doi:10.1029/2003JD004106.

    • Search Google Scholar
    • Export Citation
  • Mo, K. C., , J. N. Paegle, , and R. W. Higgins, 1997: Atmospheric processes associated with summer floods and droughts in the central United States. J. Climate, 10 , 30283046.

    • Search Google Scholar
    • Export Citation
  • Mock, C. J., 1996: Climatic controls and spatial variations of precipitation in the western United States. J. Climate, 9 , 11111125.

  • Pasch, R. J., , L. A. Avila, , and J. G. Jiing, 1998: Atlantic tropical systems of 1994 and 1995: A comparison of a quiet season to a near-record-breaking one. Mon. Wea. Rev., 126 , 11061123.

    • Search Google Scholar
    • Export Citation
  • Pytharoulis, I., , and C. Thorncroft, 1999: The low-level structure of African easterly waves in 1995. Mon. Wea. Rev., 127 , 22662280.

  • Reed, R. J., , D. C. Norquist, , and E. E. Recker, 1977: The structure and properties of African wave disturbances as observed during phase III of GATE. Mon. Wea. Rev., 105 , 317333.

    • Search Google Scholar
    • Export Citation
  • Rogers, P. J., , and R. H. Johnson, 2007: Analysis of the 13–14 July gulf surge event during the 2004 North American Monsoon Experiment. Mon. Wea. Rev., 135 , 30983117.

    • Search Google Scholar
    • Export Citation
  • Stensrud, D. J., , R. L. Gall, , S. L. Mullen, , and K. W. Howard, 1995: Model climatology of the Mexican monsoon. J. Climate, 8 , 17751794.

    • Search Google Scholar
    • Export Citation
  • Stensrud, D. J., , R. L. Gall, , and M. K. Nordquist, 1997: Surges over the Gulf of California during the Mexican monsoon. Mon. Wea. Rev., 125 , 417437.

    • Search Google Scholar
    • Export Citation
  • Tang, M., , and E. R. Reiter, 1984: Plateau monsoons of the Northern Hemisphere: A comparison between North America and Tibet. Mon. Wea. Rev., 112 , 617637.

    • Search Google Scholar
    • Export Citation
  • Thorncroft, C., , and K. Hodges, 2001: African easterly wave variability and its relationship to Atlantic tropical cyclone activity. J. Climate, 14 , 11661179.

    • Search Google Scholar
    • Export Citation
  • Wilks, D. S., 1995: Statistical Methods in the Atmospheric Sciences: An Introduction. Vol. 59, International Geophysics Series, Academic Press, 467 pp.

    • Search Google Scholar
    • Export Citation
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Relationship between Tropical Easterly Waves and Precipitation during the North American Monsoon

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  • 1 Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, and NOAA/National Severe Storms Laboratory, Norman, Oklahoma
  • | 2 NOAA/National Severe Storms Laboratory, Norman, Oklahoma
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Abstract

Relationships between tropical easterly waves (TEWs) and precipitation over Mexico and the United States are examined during the North American monsoon (NAM). The National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis data are used to identify 137 TEWs that cross Mexico north of 20°N after monsoon onset over a 31-yr period from 1975 to 2005. Mean precipitation anomalies over two-day periods both before and after TEW passage are determined using Climate Prediction Center daily precipitation analyses. Results indicate that positive precipitation anomalies occur along the west coast of Mexico and extending into the west-central United States in association with TEW passage. Negative precipitation anomalies are found in the south-central United States. These precipitation anomaly patterns share many similarities to precipitation anomaly patterns previously defined in association with gulf surge events. On longer time scales, correlations between the total number of these northern TEWs crossing Mexico and 90-day monsoon period precipitation anomalies are also examined. An out-of-phase relationship is found between monsoon period precipitation anomalies in the southwestern and south-central United States, suggesting that increasing the number of northern TEWs crossing Mexico leads to enhanced monsoon period rainfall in Arizona and New Mexico and reduced monsoon period rainfall in Texas and Oklahoma. Thus, these northern TEWs likely play an important role in producing the distribution of precipitation throughout the NAM region and the south-central United States during the monsoon season, and extended-range predictions of northern TEW frequency may lead to improved seasonal rainfall anomaly forecasts in these regions.

Corresponding author address: Dr. David J. Stensrud, National Severe Storms Laboratory, National Weather Center, 120 David L. Boren Blvd., Norman, OK 73072. Email: david.stensrud@noaa.gov

Abstract

Relationships between tropical easterly waves (TEWs) and precipitation over Mexico and the United States are examined during the North American monsoon (NAM). The National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis data are used to identify 137 TEWs that cross Mexico north of 20°N after monsoon onset over a 31-yr period from 1975 to 2005. Mean precipitation anomalies over two-day periods both before and after TEW passage are determined using Climate Prediction Center daily precipitation analyses. Results indicate that positive precipitation anomalies occur along the west coast of Mexico and extending into the west-central United States in association with TEW passage. Negative precipitation anomalies are found in the south-central United States. These precipitation anomaly patterns share many similarities to precipitation anomaly patterns previously defined in association with gulf surge events. On longer time scales, correlations between the total number of these northern TEWs crossing Mexico and 90-day monsoon period precipitation anomalies are also examined. An out-of-phase relationship is found between monsoon period precipitation anomalies in the southwestern and south-central United States, suggesting that increasing the number of northern TEWs crossing Mexico leads to enhanced monsoon period rainfall in Arizona and New Mexico and reduced monsoon period rainfall in Texas and Oklahoma. Thus, these northern TEWs likely play an important role in producing the distribution of precipitation throughout the NAM region and the south-central United States during the monsoon season, and extended-range predictions of northern TEW frequency may lead to improved seasonal rainfall anomaly forecasts in these regions.

Corresponding author address: Dr. David J. Stensrud, National Severe Storms Laboratory, National Weather Center, 120 David L. Boren Blvd., Norman, OK 73072. Email: david.stensrud@noaa.gov

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