MUWIC Newsletter - September 2004

(Issued: September 2, 2004)

 

Millersville University Weather Information Center (MUWIC)

Eric J. Horst, Director

 

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LEAD STORY: “Lack of Heat & Frequent Storms Make for a Memorable Summer ”

 

It was a memorable summer—let me count the ways. June through August featured the most summertime rainfall since 1996. Through the end of August we experienced only five 90-degree days; that’s just twenty-two percent of normal and the fewest since 1996. At least ten tornados touched down within a 75-mile radius of Lancaster, with three touching down within the county. Last but not least, a catastrophic hurricane (Charley) made landfall in Florida resulting in an estimated 7.5 billion dollars of damage. Whew, what a summer!

 

Locally, we can blame the jet stream for producing the frequent storms and lack of extreme heat. These upper-level “steering winds” normally retract into Canada during the summer months, yet this year the jet stream remained south across the Great Lakes and the Northeast. This pattern drove a parade of cold fronts through our area, many of which touched off heavy showers and gusty storms. What’s more, the ongoing jet stream trough in the East prevented the development of a bonafide Bermuda high pressure center as well as any enduring heat. While this will not go down as the coolest summer on record, it did feature one of the lowest numbers of 90-degree days.

 

 

 

90-Degree Days (MU Weather Center):

 

                        Normal             2002               2003                2004

April                     0.5                   3                      0                      0

May                     1.5                   0                      0                      1

June                     5                      6                      3                      1

July                      9                    18                      3                      1

August                  6                    16                      3                      2

September            2                      2                      0                      ?

 

Total                 24*                  45                      9                      5 (thru 8/31)

 

* Record fewest 90-degree days is 3 (1960)

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EVENT OF THE MONTH

 

Although he tracked well east of Lancaster, Hurricane Charley was the weather event of the month. Charley grew to Category 4 strength before making landfall along Charlotte Harbor on the southwest coast of Florida. Sporting winds in excess of 125 mph, Charley produced widespread catastrophic damage making it one of the costliest natural disasters in U.S. history.

 

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AUGUST CLIMATOLOGY (MU Weather Station)

 

Average High Temp: 82.5 F

Average Low Temp: 63.6 F                                                   

Average Monthly Temp: 73.1 F                                         

(Departure from Normal: +0.6 F)

                                       

Precipitation: 4.55 inches  

(Departure from Normal: +0.58)   

Annual Precipitation: 29.39 inches              

(Departure from Normal: +1.08)

 

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SEPTEMBER NORMALS, RECORDS & FACTS

 

Fall officially arrives at 12:30 p.m. on the 22nd (autumnal equinox). Normal rainfall for September is 3.62 inches, and normal high and low temperatures range from 82/59 (high/low) on the 1st to 71/47 on the 30th. On average, there are eight days with measurable precipitation (third lowest monthly average) and two days with a high temperature of 90F or above. The record high for September is 99F (9/3/53) and the record low is 27F (9/26/22).

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SEPTEMBER OUTLOOK

 

A significant pattern change occurred during the third week of August as the jet stream pattern flipped configuration. For most of the summer, troughiness dominated over the Northeast causing an unusual amount of clouds and storms along with a lack of sustained heat. Over the last two weeks, however, the mean trough has reformed over the west as a Bermuda high pressure center tries to take hold in the East. The upshot locally was two 90-degree days (since August 20th) and a decided drop-off in shower activity. Heading into September, the big question relates to whether or not this new pattern can hold on long-term.

 

Unfortunately, I can’t provide a definitive answer. I see the ridge hanging on in the East short term, yet I also see an active jet stream that could try to redevelop a trough in the East sometime later this month. Thus, I don’t have a strong signal to leverage in this monthly outlook—in the end, the month may be typified by a progressive pattern that shows us many facets of summer and fall-like weather. Temperature statistics may be a wash with an equal number of below- and above-normal days. It terms of rainfall, it may be a literal wash if the remnants of Hurricane Frances (or another tropic system) move into the area. Monthly rainfall could approach double of normal (3.62) should a tropical system track through the region, otherwise, September precipitation should be near or slightly below normal.

 

COPYRIGHT 2004 Millersville University

 

Published monthly by the Millersville University Weather Information Center.

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