The MJO and Annual Rainfall in California

Several hydro-climate indices are used to characterize the strength and cycle of ENSO, to measure activity of the Madden-Julian Oscillation (MJO), which is the largest element of intra-seasonal (30 – 90 days) variability in the tropics, and to characterize several additional hydro-climate indices that reflect changes in pressure and height anomalies, circulation anomalies, and SSTs throughout the globe. Several of these indices, those related to ENSO and the MJO in particular, have been linked to variability in precipitation within the … Read More

Stage 1: Thunderhead

The first stage of a thunderstorm begins with instability, which creates potential energy, and a mechanism to release the instability or create lift.  Instability is created when the warm air inside a cloud is warmer than the surrounding environment.  Lift can be created by a front, such as a cold or warm front, an area of low pressure (low pressure trough), or air rising up a slope.  As the air rises, some of this air condenses to form the water droplets … Read More

Shelf Cloud

The shelf cloud is one of the most misidentified clouds types; they are often mistaken for wall clouds.  There are many stark differences between a shelf cloud and a wall cloud that makes either of them easy to identify.  A shelf cloud can be found at the leading edge of a storm while the wall cloud, if it is present, will be located on the back side and along the base of the storm just behind the rain.  A shelf … Read More

Formation of Lightning

This video shows the process by which lightning strikes the ground using extremely slow motion recording technology.  You can see how several tendrils drop from the sky, and as they approach objects on the ground, tendrils from these objects extend up toward them.  Lightning occurs when one tendril from above connects with one tendril from an object on the ground, thus draining the charge to the ground.

Inside a Tornado

If you have ever wondered what it would be like to be inside a tornado, watch this video before attempting anything that is potentially life threatening.  These are supposedly professional storm chasers using a heavily armed vehicle, which is not shown in the video, so do not try this on your own.

Introduction to Hydro-FIT

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Hydro-FIT is a statistical tool developed by HydroMetriks, LLC, that facilitates the frequency analysis of various types of hydrological and meteorological data.  Hydro-FIT uses the method of L-moments to calculate descriptive statistics (L-moments) for a dataset. These L-moments are used to fit any of 13 different standard distributions, which are used to estimate the growth curve of the data.  Hydro-FIT also has the ability to estimate the impacts of climate variability on event frequency and intensity.  The objective has been to … Read More

“Regional Frequency Analysis” by Hosking & Wallis

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The book titled “Regional Frequency Analysis: An Approach Based on L-Moments” is the current authority on using L-Moments in any type of frequency analysis.  Every step of the process is described in detail and examples are given along the way to make the method clear.  The code that was developed into the current version of Hydro-FIT was inspired by and mimics the steps described in this book.  Obtaining and reading a copy of “Regional Frequency Analysis” is highly recommended.  This … Read More

“Data Screening” Window

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The “Data Screening” window is the initial window following the “Title Screen” from which you may load and screen the data that you would like to analyze.  This window is divided into three panels titled ‘Load Data’, ‘Data Screening’, and ‘Index Analysis’.  After the data input file is selected, you can choose the resolution of the data, the analysis and data types, the beginning year (in the case of extreme value analysis or beginning month (if a specific period of the year is … Read More

Index Analysis Plot

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Hydro-FIT has the ability to calculate the correlation between 39 different global climate indices and the input data using a lag time that is supplied by the user.  By clicking the ‘Graph’ button on the “Data Screening” window and using the specified lag time, Hydro-FIT will display plots of the global climate indices vs. the input data for the five climate indices with the highest correlations along with their respective values of R2.  The relationship between any of these indices and … Read More

“Site Analysis” Window

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The screen that appears after clicking the ‘Site Analysis’ button within the ‘Data Screening’ window is called the ‘Site Analysis’ window.  The ‘Site Analysis’ window is organized into four parts that allow the user to select a valid site (determined during data screening) and view pertinent statistics associated with that site, to display any of a variety of plots pertaining to the selected site or to all sites as a whole, to select one or more standard distributions to display … Read More

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