MUWIC Newsletter - August 2002

(Issued: August 2, 2002)

Millersville University Weather Information Center (MUWIC)

Eric J. Horst, Director

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LEAD STORY: "Drought Takes a Turn for the Worse"

Just a month ago, the local drought conditions had improved on the heels of two straight months of near-normal rainfall. Unfortunately, the drought has taken a turn for the worse due to the third warmest and fourth driest July on record. Temperatures for the month averaged 3.4 degrees above normal, while the total precipitation across the county averaged less than an inch.

According to the National Weather Service, Lancaster is the driest county in the Commonwealth over the last 180 days. While 14 counties remain in a drought emergency, Lancaster county is, in fact, ground zero. As of the end of July, the weekly Palmer Index of drought severity reveals the need for short-term rainfall in excess of eight inches in order to end the drought. I have little hope we'll see that kind of rainfall anytime soon.

Rainfall Statistics (MU Weather Center):

Normal Actual DFN

January 3.01 2.38 -0.63

February 2.47 0.27 -2.20

March 3.38 3.09 -0.29

April 3.47 1.79 -1.68

May 3.62 3.51 -0.11

June 3.88 3.63 -0.25

July 4.51 0.74 -3.77

Total 24.34 15.41 -8.93

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EVENT OF THE MONTH

On the evening of July 19th, a lone thunderstorm formed over a small area of southern Lancaster county. The storm remained nearly stationary for an hour, dropping between one and six inches of rain near Truce, Quarryville and the Buck.

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STAT OF THE MONTH

Temperatures reached or exceeded the 90-degree mark on 18 days in July. The long-term average number of 90-degree days in July is nine, while the monthly record is twenty-one days (1921 and 1955).

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JULY CLIMATOLOGY (MU Weather Station)

Average High Temp: 88.8 F

Average Low Temp: 67.5 F

Average Monthly Temp: 78.1 F

(Departure from Normal: +3.4 F)

Precipitation: 0.74 inches

(Departure from Normal: -3.77)

Annual Precipitation: 15.45 inches

(Departure from Normal: -8.93)

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AUGUST NORMALS, RECORDS & FACTS

Normal high/low temperatures decrease from 86/63 on August 1st to 83/59 by month's end. The record high for August is 107 degrees set on the 7th of 1918, while the record low is 35 F set on the 29th in 1982. Normal liquid precipitation for the month is 3.97 inches. The rainiest August on record (13.94 inches) occurred in 1933. The driest August was in 1957 when only 0.51 inches fell.

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AUGUST OUTLOOK

August is starting the way July ended--hot, humid and mainly dry! However, a significant break in the heat is on tap for the period of August 6 th to 8th. A strong cold front will usher in unseasonably chilly air for a few days and, in fact, the Canadian air mass will push our temperatures closer to setting a record low than a record high. Unfortunately, the comfortable conditions won't last.

The heat will rebuild into our region beginning August 9th and temperatures might return to the low 90s for a few days towards mid-month. Beyond that, the pattern is a tough call as a strengthening jet stream develops across southern Canada. It's possible a second cold front will drop into the Commonwealth around August 15th, or it might be held at bay by a Bermuda high pressure pumping up over the Southeast states. My sense is that the cold front will make it as far south as our region, but I'm uncertain how much cooling will result.

Overall, I suspect August will conclude a couple degrees above normal, though, the worst of this summer's heat is past us. The more important matter is precipitation, and I'm afraid I don't see significant improvement in the drought situation this month. Short of a tropical storm moving into the area with soaking rains, I only see more of the typical hit-or-miss showers this month. Therefore, I expect the drought emergency will continue into September.