Pennsylvania Long Range Forecast:
Expected Temperature and Precipitation Departures for November and December 2004 by Climate Division
Precipitation over the summer of 2004 was much above normal. Across Pennsylvania's ten state climate divisions, there was on average 6.13" more rainfall than average over June, July and August. This abundance of precipitation made for the 5th wettest summer on record. Temperatures over the entire state were cooler than average, as this summer ranked 83rd warmest out of 106 years.
Here is a summary of Summer 2004 by Climate Division: (DFN=departure from normal)
| Division | Temp DFN | Temp Rank | Precip DFN | Precip Rank |
| 1 | -0.6 ° F | 72 of 106 | +8.44" |
2 of 106 |
| 2 | -0.4 ° F | 64 of 106 | +9.23" | 1 of 106 |
| 3 | -0.7 ° F | 75 of 106 | +7.97" | 1 of 106 |
| 4 | -1.3 ° F | 93 of 106 | +6.07" | 5 of 106 |
| 5 | -1.2 ° F | 80 of 106 | +3.75" | 7 of 106 |
| 6 | -1.1 ° F | 77 of 106 | +8.99" | 1 of 106 |
| 7 | -0.9 ° F | 75 of 106 | +5.42" | 4 of 106 |
| 8 | -3.0 ° F | 105 of 106 | +3.00" | 13 of 106 |
| 9 | -1.2 ° F | 84 of 106 | +4.86" | 5 of 106 |
| 10 | -2.6 ° F | 103 of 106 | +3.55" | 13 of 106 |
| AVERAGE | -1.3 ° F | 83 of 106 | +6.13" | 5 of 106 |
Using these anomalies as a basis, the PA Climate Office has produced a divisional forecast of expected departures from normal for temperature and precipitation in November and December. The following methodlogy was used in producing the divisonal outlook:
1) Identify and rank the wettest summers (prior to 2004) on record.
2) Starting from the summer of greatest precipitation, find the six years with the wettest summers that were also below normal in summer temperatures.
3) Obtain temperature and precipitation departures from normal in November and December for each of those years.
4) Calculate the average temperature departures from normal for all analog years.
5) Calculate the precipitation departures from normal for all analog years.
6) Results represent expected temperature and precipitation departures from normal for November and December.
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PREDICTIONS:
PRECIPITATION: Precipitation should average somewhat above normal for both November (average of +0.56" DFN) and December (average of +0.45" DFN) throughout the state.
TEMPERATURE: There is a strong correlation between cool, wet summers and cool November temperatures. Temperatures should be below normal in all areas of the state (average DFN of -2.3 ° F) during the eleventh month. December shows a wide range of possibilities for each climate division and thus provides no clear trend with this set of analog years. Overall, temperature departures round out to near normal (average DFN of +0.2 ° F).
SJG 9/04