MUWIC
Newsletter - June 2004
(Issued: June 2, 2004)
Millersville University Weather Information Center (MUWIC) Eric J. Horst, Director
************************************************************************ LEAD STORY: “Warmest May on Record”
“April showers bring record May warmth?” This certainly has a strange ring to it, but that’s just what Mother Nature delivered this Spring. After the wettest April in twelve years, May brought unprecedented warmth and a record aggregate temperature anomaly of +6.9 F. Ironically, the month ended with three consecutive below normal days as unseasonably chilly air arrived for the Memorial Day weekend. May’s persistent warmth resulted from a summer-like jet stream pattern that featured the classic Bermuda high pressure along the east coast for over two weeks. The seventeen-day stretch of May 9th to the 25th produced fourteen 80-degrees days and one 90-degree day. This compared to just a two 80-degree days during all of May 2003. Other than dodging occasional showers and thunderstorms, Pennsylvania’s agricultural interests reveled in the weather this Spring. Unusually warm overnight lows prevented any serious late-season frosts, while near-average rainfall has maintained soil moisture. Furthermore, the Climate Prediction Center’s Long-Term Drought Indicator shows our area as possessing plentiful water resources and, thus, it seems that drought conditions are unlikely anytime soon. Top 5 Warmest Mays (departure from normal)*
* - Based on 90-year Millersville/Lancaster database. ************************************************************************ EVENT OF THE MONTH
Mothers’ Day produced isolated flooding as up five inches of rain fell over a small portion of the Lower Susquehanna Valley. Tragically, a York county women and her child drowned while driving across a flooded road. The heaviest storms fortunately missed Lancaster county with less than an inch falling in most areas. ************************************************************************ STAT OF THE MONTH
The period of May 9th through the 15th featured consecutive high temperatures over 80 degrees. The last seven-day stretch of such sultry highs occurred from August 17 - 23, 2003. ************************************************************************ MAY CLIMATOLOGY (MU Weather Station)
Average High Temp: 78.3 F Average Low Temp: 59.5 F Average Monthly Temp: 68.9 F (Departure from Normal: +6.9 F)
Precipitation: 3.06 inches (Departure from Normal: -0.56) Annual Precipitation: 14.16 inches (Departure from Normal: -1.79) ************************************************************************ JUNE NORMALS, RECORDS & FACTS
Normal high/low temperatures range from 80/54 on June 1st to 85/61 by month’s end. The record high for June is 103 degrees set on the 20th of 1923 and 29th of 1934. The lowest temperature recorded in June is 33 F set on the 5th of 1921 and the 8th of 1932. Normal liquid precipitation for the month is 3.88 inches. The rainiest June on record (14.14 inches) occurred in 1972 when the remains of Hurricane Agnes moved through the region. The driest June was in 1966 when only 0.54 inches fell. Summer officially begins on June 20th at 8:57 p.m. ************************************************************************ JUNE OUTLOOK
After the warmest May on record in the Lancaster area, June looks to begin on a more seasonable note as the upper-level flow pattern evolves into a more zonal configuration. In fact, a broad trough will dominate the first week of June from the Upper Midwest to the Mid-Atlantic region. A series of jet stream disturbances will move through this weak trough position touching off isolated thunderstorms every few days. Between these disturbances, high pressure will bring unseasonably chilly air from Canada. As each high pressure exits, a one-day warm-up is possible ahead of the next approaching cold front. I expect one front to move through today (June 2nd), with another around Monday June 7th.
Beyond that, I see continued weakness in the upper-level pattern over the Northeast while the core of warmest air expands over the central states. Warm air may try to build into our region around June 10th, however, the magnitude of downstream blocking remains a major question as to how big of a warm-up will occur here. Should the jet stream blocking over the north Atlantic remain in place, we would likely remain in northwesterly flow with a continuation of normal to below normal conditions. When the block finally exits, a significant warm-up will occur with a return to high temps in the 80s for the second half of the month. Still, “low 80s” is normal for June, so the month may average out slightly below normal. Precipitation-wise, we’ll be looking at the passing fronts every few days as our primary source of rainfall. Given the current pattern—which lacks Gulf moisture influx—you might expect a bit less rainfall than normal. Of course, it only takes one good thunderstorm “hit” at a given location to produce near-normal monthly precipitation. Thus, in typical summer fashion, total rainfall could vary greatly from location to location. COPYRIGHT 2004 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 *** ********************************************************************** |