d. A period of prolonged (>24 hr) deepening; while the Halloween Storm 

 did not meet the explosive deepening criterion (18mb/24hr at 

 latitude 40°) of Sanders and Gyakum (1980), it did deepen at a rate 

 equivalent to 15mb/24hr for 48 hr. 



In addition to the above conclusions, it also may be inferred that there has 

 been a significant decline in the number of retrograde storms in the 1980-1989 

 decade as compared with the two previous decades (21 versus 36 average). 

 However, this may not be a statistically valid conclusion given the relatively 

 short history we have assembled. 



Conclusions concerning determination of occurrence frequency for small, 

 rapidly intensifying storms such as the 4-5 January 1992 event will be difficult 

 to draw because of the inability of the synoptic weather products to adequately 

 depict these events. This makes the parent population of these storms difficult 

 to identify. 



Recommendations include developing a method to compensate for the 

 apparent bias toward higher central pressures, smaller size, and shorter duration 

 derived from operational analysis depictions. In addition, vorticity fields, in 

 addition to the height and temperature fields, may provide additional support to 

 the tentative conclusions drawn and additional insight to the event development 

 process. 



46 



Chapter 8 Summary and Conclusions 



