Journal ArticleDOI
An Analysis of a Mesocyclone–Induced Tornado Occurrence in Northern California
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TLDR
In this paper, the parent thunderstorm had supercellular characteristics and the tornado was mesocyclone-induced, and a quasi-stationary leeside trough acted in concert with local channeling effects to promote the advection of relatively moist air to the northern portions of the Valley.Abstract:
One documented F2 tornado and several other unconfirmed tornadoes were reported in California's Sacramento Valley on 24 September 1986. The synoptic pattern which occurred that day was one long-recognized by California operational meteorologists as being associated with severe weather in the state. The present study documents this event and shows that the parent thunderstorm had supercellular characteristics and that the tornado was mesocyclone-induced. As is the case elsewhere when severe thunderstorms are observed, the mesoscale environment established a focus for late morning and early afternoon deep convection. A quasi-stationary leeside trough acted in concert with local channeling effects to promote the advection of relatively moist air to the northern portions of the Valley. This channeled flow contributed to low-level shear which was much stronger than that evident in the Oakland hodograph and one which was comparable to that found with supercell and mesocyclone development elsewhere in t...read more
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Journal ArticleDOI
Severe Local Storms Forecasting
TL;DR: In this paper, the authors present a review of the current knowledge of severe local storms as it relates to the development of new applications for forecasting of local storms. But, they focus on the physical understanding of processes taking place on the storm scale and thus allow forecasters to become less dependent on empirical relationships.
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Severe Local Storms Forecasting
TL;DR: Riebsame et al. as mentioned in this paper reported that local convective storm-induced severe weather and floods result in approximately 400 fatalities annually, with excessive heat and cold accounting for about 600 deaths and hurricanes for more than 30 fatalities each year.
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Shear Parameter Thresholds for Forecasting Tornadic Thunderstorms in Northern and Central California
TL;DR: A study of 39 nontornadic and 30 tornadic thunderstorms (composing 25 tornado events, as defined in the text) that occurred in northern and central California during the period 1990-94 shows that stratification of the stronger tornadic events (associated with F1 or greater tornadoes) on the basis of 0−1- and 0−6-km positive and bulk shear magnitudes is justified statistically as mentioned in this paper.
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Recent Trends in Four Common Stability Indices Derived from U.S. Radiosonde Observations
TL;DR: In this article, the authors extracted from 48 radiosonde stations in the contiguous United States to assemble a ∼50 yr record of four common stability indices: the Lifted Index, the K-Index, convective available potential energy (CAPE), and the Air Force Severe Weather Threat Index.
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Utilizing Normalized Anomalies to Assess Synoptic-Scale Weather Events in the Western United States
TL;DR: The top 20 most anomalous events were identified over the western United States, adjacent eastern Pacific Ocean, Mexico, and Canada as mentioned in this paper, and the events included the northern Intermountain West region heavy rainfall and Yellowstone tornado of mid-July 1987 (ranked 5th), the Montana floods of September 1986 (ranked 4th).