Abstract Title

Variability of the North American Monsoon

Faculty Mentor Name

Mark Sinclair

Format Preference

Poster

Abstract

Each summer, the North American Monsoon (NAM) causes a marked increase in thunderstorms and rainfall over the Southwestern United States. Monsoon precipitation occurs when there is a transition from westerlies to southwesterlies, and typically occurs when the high-pressure system moves north from its winter location and stalls near the Four Corners region. The Desert Southwest receives up to half of their annual precipitation from monsoon thunderstorms. These short lived, powerful storms can bring heavy rain, hail, flash flooding and frequent lightning. It is most predominant between the months of July and September. The NAM is not continuous, as its considerable variation relies on many factors, including the amount of moisture being advected into the region and the position of the high pressure/anticyclonic flow. If the high-pressure system is not in a favorable position to bring moisture into the Southwest region, a break in thunderstorm activity may occur. Understanding the variability of the NAM can help with regional flash flood and drought forecasting. This study will identify some of the sources of the variability in summer precipitation experienced over the last 65 years by analyzing El Nino’s influence on the onset of summer precipitation, along with smaller scale influences such as local topography, movement of the high-pressure system and sea surface temperatures in the northern Gulf of California.

Location

AC1-ATRIUM

Start Date

3-31-2017 11:00 AM

End Date

3-31-2017 3:00 PM

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Mar 31st, 11:00 AM Mar 31st, 3:00 PM

Variability of the North American Monsoon

AC1-ATRIUM

Each summer, the North American Monsoon (NAM) causes a marked increase in thunderstorms and rainfall over the Southwestern United States. Monsoon precipitation occurs when there is a transition from westerlies to southwesterlies, and typically occurs when the high-pressure system moves north from its winter location and stalls near the Four Corners region. The Desert Southwest receives up to half of their annual precipitation from monsoon thunderstorms. These short lived, powerful storms can bring heavy rain, hail, flash flooding and frequent lightning. It is most predominant between the months of July and September. The NAM is not continuous, as its considerable variation relies on many factors, including the amount of moisture being advected into the region and the position of the high pressure/anticyclonic flow. If the high-pressure system is not in a favorable position to bring moisture into the Southwest region, a break in thunderstorm activity may occur. Understanding the variability of the NAM can help with regional flash flood and drought forecasting. This study will identify some of the sources of the variability in summer precipitation experienced over the last 65 years by analyzing El Nino’s influence on the onset of summer precipitation, along with smaller scale influences such as local topography, movement of the high-pressure system and sea surface temperatures in the northern Gulf of California.