The temperature and precipitation forecasts for September & October 2004 are compiled using an analog forecasting approach. This analog approach compares regional surface temperature and precipitation deviations from normal for August 2004 to years with similar regional deviations throughout the United States. The following years experienced Augusts with anomalies resembling the temperature and precipitation anomalies of this past August: 1950, 1966, 1967, 1986, 1992 and 1997. These five years serve as the basis of the August/September analog forecast.
Anticipated temperature anomalies for September 2004 include:
· Warm anomaly throughout the North Central and Northwestern US
· Warm anomaly in Southern Texas, Southeast New Mexico, South Florida,
and the West coast
· Extremely cold anomaly throughout the Eastern seaboard, as well as
areas in the Mid-South and Great Plains region.
· Cold anomaly in southern California, south Nevada, Southern Utah and
North Arizona
The September 2004 temperature anomaly map predicts warm conditions for most of the North and Northwestern US, mostly in the Northern states west of the Mississippi bordering Canada. The map shows a strong tendency for Eastern and Central areas of the US to see anomalously cooler than normal temperatures, the temperature outlook for Pennsylvania being well below normal.
Anticipated precipitation anomalies for September 2004 include:
· Dry anomaly along the Eastern seaboard down through
South Florida, and in areas boarding the Gulf of Mexico.
· Dry anomaly in North Minnesota, North Wisconsin, and Northern North
Dakota
· Wet anomaly in the Rockies, along the West Coast, South Dakota, Nevada,
and in regions of Texas.
· Wet anomaly in north Michigan, Illinois, West New York, and West Virginia.
The September 2004 precipitation anomaly map predicts dry conditions for areas
along the Atlantic coast and down and around the Florida panhandle through states
bordering the Gulf of Mexico. Above normal precipitation is predicted for states
in the Rocky Mountain range and along the Western Seaboard. Regions of wetter
than normal returns of note also include South Dakota, North Michigan, and the
Southwestern US. Precipitation predictions for Pennsylvania have only a slight
return, with wetter than normal conditions in the central and northwest regions,
and dry conditions in the East.
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).
