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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