The temperature and precipitation forecasts for July & August 2004 are compiled using an analog forecasting approach. This analog approach compares regional surface temperature and precipitation deviations from normal for June 2004 to years with similar regional deviations throughout the United States. The following years experienced Junes with anomalies resembling the temperature and precipitation anomalies described below: 1949, 1957, 1992 and 2000. These four years serve as the basis of the July/August analog forecast.
Temperature anomalies utilized for June 2004 included the following:
· Warm anomaly on the northern California/Nevada border
· Cold anomaly throughout the Northeast
· Cold anomaly throughout northern Montana, North Dakota, and Minnesota
The July 2004 temperature anomaly map predicts warm conditions in the southernmost tier of the US, particularly in the Florida panhandle where the departure from normal is around +1 standard deviation. The map predicts cold anomalies throughout the Northeast, Northwest, northern California, and Michigan. The temperature outlook throughout Pennsylvania ranges from normal to slightly below normal.
Precipitation anomalies utilized for June 2004 included the following:
· Wet anomaly throughout eastern Texas, Oklahoma, Kansas, Colorado, southern Arkansas, Louisiana, Mississippi, Alabama and Florida
· Dry anomaly throughout the Northeast
· Dry anomaly throughout eastern Montana, North Dakota and northern Minnesota
· Dry anomaly throughout California and Nevada, as well as parts of Utah and Arizona
The July 2004 precipitation anomaly map predicts dry conditions for most of
the southern US, Nevada and Idaho. Wetter than long term average conditions
are predicted for the central and Midwest US, as well as parts of Pennsylvania
and New York. Precipitation predictions for Pennsylvania vary by climate region.
In general, predictions demonstrate drier than normal conditions for southeast
Pennsylvania, while the remainder of the state demonstrates normal to slightly
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).
