MUWIC Newsletter - July 2002

(Issued: July 1, 2002)

 

Millersville University Weather Information Center (MUWIC)

Eric J. Horst, Director

 

************************************************************************

 

LEAD STORY: "Drought: Down, But Not Out”

 

A significant late-April change in the jet stream pattern initiated a dramatic two-month turnaround in the severity of the drought conditions. Since April 20th, normal to above-normal rainfall has fallen across the Commonwealth and six of the 20 counties in a Drought Emergency (since 2/12/02) have recently been downgraded to a Drought Warning. However, Lancaster and other southeastern Pennsylvania counties remain in a Drought Emergency with mandatory water-use restrictions in effect.

 

So, when will the Drought Emergency be lifted in our area? As of the end of June, we remain below normal on year-to-date rainfall and, according to the National Weather Service’s Palmer Index, we need about three inches of rain to end the drought. However, evaporation rates are now at their highest levels (as we head into the hottest month of the year) and it seems unlikely that we will receive the three inches needed to end the drought, in addition to the rainfall required to offset day-to-day evaporation. Thus, it’s quite possible the drought designation will continue into August or even the Fall months.

 

Rainfall Statistics (MU Weather Center):

 

                        Normal Actual              DFN

January 3.01                 2.38                 -0.63

February          2.47                 0.27                 -2.20

March              3.09                 3.38                 -0.29

April                 3.47                 1.79                 -1.68

May                 3.62                 3.51                 -0.11

June                 3.88                 3.63                 -0.20

 

Total                19.83               14.71               -5.12               

 

************************************************************************

 

EVENT OF THE MONTH

 

A strong cold front passed through on the evening of June 6th triggering a round of heavy thunderstorms that produced heavy downpours and wind gusts up to 78 mph. Isolated areas of tornado-like wind damaged occurred in parts of Lancaster—this damage was likely the result of straight line winds that accompanied the briefly torrential downpours.

 

************************************************************************

 

MAY CLIMATOLOGY (MU Weather Center)

 

Average High Temp: 83.2 F

Average Low Temp: 62.1 F                                                   

Average Monthly Temp: 72.6 F                                         

(Departure from Normal: + 2.3 F)

                                       

Precipitation: 3.63 inches  

(Departure from Normal: -0.25)   

Annual Precipitation: 14.71 inches              

(Departure from Normal: -5.12)

 

************************************************************************

 

JULY NORMALS, RECORDS & FACTS

 

Climatologically the warmest month of the year, daily average temperatures peak on July

18th and 19th with a normal high/low of 87/65. The record high for July is 104 degrees set on three different occasions (July 3, 1966, July 10, 1936, and July 21, 1930) and the

record low is 42 set on Independence Day in 1918. Normal precipitation for the month is

4.51 inches. The rainiest July on record occurred in 1941 when 9.48 inches fell. The

driest July was in 1955 when only 0.60 inches fell.

 

************************************************************************

 

JULY OUTLOOK

 

I see no big changes in the overall pattern from what we experienced during most of June. That is, the mean jet stream ridge will be positioned just east of the Rockies with the warmest conditions in the plains and a weak jet stream trough will, at times, amplify into the Northeastern US. In June, the end result (locally) was a couple of short heat waves punctuated by cold frontal passages and a couple rounds of heavy storms.

 

Though temperatures will be warmer in July compared to June (which is normal), I expect the monthly “departure from normal” to be similar to the +2.3F we experienced in June. Precipitation is the wild card in this monthly outlook, since higher frequency of showers this month could hold temperatures down and, possibly, bring an end to our Drought Emergency. However, I expect the hit-or-miss nature of the storms may not provide the widespread rain we would need to end the drought…so I’m not optimistic that the next 30 days will bring us above normal rainfall.

 

COPYRIGHT 2002 Millersville University

 

Published monthly by the Millersville University Weather Information Center.

Subscribe on our homepage at www.atmos.millersville.edu/~wic

 

************************************************************************

             *** Bookmark our web site at: www.atmos.millersville.edu/~wic ***

************************************************************************