June/July 2004 Experimental Forecast for Pennsylvania

At the beginning of each month, the Pennsylvania State Climate Office presents an experimental temperature forecast for the Commonwealth.  It will be routinely compared with actual observations for verification purposes.

To view the verification of the June/July 2004 forecast, visit the Verification Page.

The temperature and precipitation forecasts for June & July 2004 are compiled using an analog forecasting approach. This analog approach compares regional surface temperature and precipitation deviations from normal for May 2004 to years with similar regional deviations throughout the United States. The following years experienced Mays with anomalies resembling the temperature and precipitation anomalies described below: 1956, 1962, 1970, 1987 and 1996. These five years serve as the basis of the June/July analog forecast.

Temperature anomalies utilized for May 2004 included the following :
· Warm anomaly throughout the Northeast
· Warm anomaly on the northern California/Nevada border
· Cold anomaly throughout southern Texas and Southern Louisiana
· Cold anomaly throughout northern Montana, North Dakota, and Minnesota

The June 2004 temperature anomaly map indicates warm conditions in the northcentral region of the US, particularly in North Dakota where the departure from normal is around +1 standard deviation. The map predicts cold anomalies throughout Louisiana, Mississippi, Alabama and Georgia. The temperature outlook throughout Pennsylvania ranges from normal to slightly above normal.

Precipitation anomalies utilized for May 2004 included the following:
· Wet anomaly throughout the northern US spanning from Minnesota to New York
· Wet anomaly throughout southern Texas and Louisiana
· Dry anomaly throughout northern Texas and Oklahoma

The June 2004 precipitation anomaly map implies dry conditions for the northcentral region of the US and wetter than long term average conditions in the southernmost portions of Louisiana, Mississippi and Alabama. Precipitation indications for Pennsylvania varies by climate region and covers the departure spectrum. In general, predictions demonstrate drier than normal conditions for northeast PA while the remainder of the state demonstrates normal to above normal precipitation.

Pennsylvania Temperature Forecast

Using 15-day medium range forecast temperature guidance and the likely monthly departures based on analog years, the following is a daily temperature forecast for May and June 2004 for western, central and eastern Pennsylvania.  This forecast predicts the daily average temperature departure from the 30-year average temperature (dotted line) and the five day running mean of the temperature departure (solid line).