Metr 595



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Introduction Evaluation Sheet










Author(s)  _________________________

Date _________________














1.  Has an opening sentence that is a legitimate topic sentence (provides transition

from title to paper)

















2.  Provides context for the study in several sentences that follow the opening sentence/paragraph.













3.  Provides purpose for the study
















4.  For a case study, provides historical,climatological, statistical or other evidence that

justifies the research

















5.  Has a brief summary of methodology and/or of the previous work (in the and/or of

the previous work (in the referreed literature) that supports the main approach













6.  Has a sentence(s) near the end of the section that summarizes the scope of the study

("…in this study, we will show…etc…" or something like that "...the unusual nature

of this case will be documented in this manuscript..."














7.  Has a series of sentences that summarize the organizational structure of the study (for

long papers--for shorter contributions like "Notes" or "Picture of the Month", not necessary)













8.  Has a consistent verb tense throughout*















9.  If the Introduction is multiple paragraphs, apart from (7) and (8) above, each

paragraph has a topic sentence, series of sentences that relate, and a sum-up sentence. In

infrequent instances, two sentence paragraphs are allowed, but never one sentence paragraphs.













10.  is of an appropriate length, or, if not, has too much background information that

should be placed in a separate section, or deleted (discuss which)


























Score out of 10 points:

















*  Separate out the verb tense used when referring to what the reader WILL do

 from what the author(s) DID in completing the study.




Introduction Example: Picture of the Month, MWR

First WSR-88D Documentation of an Anticyclonic Supercell with Anticyclonic Tornadoes: The Sunnyvale–Los Altos, California, Tornadoes of 4 May 1998

1. Introduction

On 4 May 1998, a pair of tornadoes occurred in the San Francisco Bay Area in the cities of Sunnyvale (F2) (2331 UTC) and Los Altos (F1) (2355 UTC) (see Fig. 1 for locations). There was an additional unverified report of a third funnel or possible tornado near the city of East Palo Alto. This represents the first instance of a tornadic thunderstorm in the San Francisco Bay region to be within close range (∼30 km) of the Monterey (KMUX) Weather Surveillance Radar-1988 Doppler (WSR-88D) site in the Santa Cruz Mountains.

The Sunnyvale tornado was well documented with both video and still images. An analysis of videotape imagery (Fig. 2 ) shows that this tornado was anticyclonic. Remarkable still images (e.g., Fig. 3 ) also reveal that it both was anticyclonic and had entrained considerable debris during its 12-min life cycle. Witness reports suggest that the tornado was multiple vortex and damage surveys determined that its pathlength was about 2 km. Video and radar evidence of the Los Altos tornado show that this was the second anticyclonic tornado produced by the same parent thunderstorm. This tornado had a pathlength of around 1 km and produced an injury as it moved through the campus of Los Altos High School.

The National Severe Storms Laboratory's (NSSL) Mesocyclone Detection Algorithm (MDA; Stumpf et al. 1998) detected mesoanticyclones several times during the life cycle of the parent storm (hereafter referred to as the Sunnyvale storm) that had formed on the left flank of an earlier thunderstorm. The motion of the Sunnyvale storm to the left of the hodograph brought it into a shear environment favorable for the development of an anticyclonically rotating updraft.

The radar evidence suggests that the Sunnyvale F2 tornado did not originate from the traditional “supercell cascade”1 process (as outlined in Wicker and Wilhelmson 1993). We speculate that the first tornado was nonsupercellular and related to the interaction of the thunderstorm with a surface boundary [see Markowski et al. (1998) for a discussion of tornadogenesis in supercells intercepting surface boundaries during the Verification of Rotation in Tornadoes Experiment]. However, the evolution of the radar signatures associated with the Los Altos tornado suggests that it may have been supercellular.

In previous studies, California supercell tornadoes have been documented with the more typical right-moving cyclonically rotating storms (e.g., Monteverdi and Quadros 1994; Braun and Monteverdi 1991) although nonsupercell tornadoes are probably the most common in the state (Blier and Batten 1994). Although radar signatures have been documented for California storms (see, e.g., Carbone 1983; Monteverdi and Johnson 1996), the hooks seen thus far were cyclonic.

There are published cases of both anticyclonic tornadoes and anticyclonic supercells in the refereed literature. Fujita (1977) provided the first documentation of anticyclonic tornadoes but did not postulate a relation of the tornadoes to the storm-scale rotation. Fujita and Grandoso (1968) first hypothesized that leftward-propagating, anticyclonic thunderstorms occur as part of storm splitting. This was verified in modeling studies by Wilhelmson and Klemp (1978) and Weisman and Klemp (1982), who showed that storms propagating to the left of the hodograph rotate anticyclonically. However, no case study of an anticyclonic tornado in association with an anticyclonic supercell has yet appeared in the reviewed literature.

The purpose of the present manuscript is to document what was a remarkable event. This is the first study that provides Doppler radar documentation of the rare combination of an anticyclonic tornado associated with an anticyclonic supercell. The fact that this unusual tornadic storm was photographed and also occurred in a region in which tornadoes and supercells are themselves relatively infrequent further establishes the uniqueness of this case.