Monday, November 10, 2008

Eric Horst - Winter Outlook '08 / '09

In addition to asking Paul Knight...WJAC-TV also wanted to know what Eric Horst...founder of the Campus Weather Service and director of the Weather Information Center at Millersville University...thought about the upcoming winter in terms of...

"More / Less snow than average
Warmer / colder than average
More / Less snow than last year
Warmer / colder than last year
Timing / type of the bigger storms
Etc.
…and some reasoning behind the forecast."
Eric has a decidedly different take regarding ENSO...

"Regarding the winter outlook…as you surely know, we do NOT have a signal from ENSO. Last winter’s rapid ramp up of a strong La Nina was a clear signal for a milder and less-snowy winter in PA…and that of course panned out nicely. With a neutral ENSO this winter, there’s no clear signal…and as I like to say it’s therefore more of an “anything goes kind of winter.” You can research past neutral ENSO winters and find both above and below temp seasons and above and below snowfall seasons, as well as many near-normal seasons.

"So which way will this winter tip? I feel that’s hard to say, because the winter will be guided by more subtle, short-lived factors such as NAO (which biases somewhat in accordance to changing SSTs in the north Atlantic) and the EPO which plays off mid-latitude pacific patterns. So, these are the signals I’ll be watching in the months to come. Unfortunately, there’s no reliable way to forecast either Index. The UKmet folks do try to model NAO…and they are forecasting a “near-neutral” NAO overall. Of course, on any given week there can be major swings negative or positive. So, I think we’d be wise to track NAO and EPO this winter to make medium-range (5 – 15 day) forecasts; big storms tend to develop when the index flips, as we saw the past few days.

"The bottom line: this winter will almost certainly be snowier and colder than last winter (which won’t be hard for most parts of PA), but I see NO strong signal to forecast a much below temp or much above snowfall winter. That can of course happen—it only takes one big storm to push snowfall much above normal…in fact, the Poconos will likely be above normal based on yesterday’s big storm padding the numbers already! Anyway, my sense is that PA will see a near- to slightly below normal temp winter and near- to somewhat above-normal snowfall winter."
WJAC-TV reports California University of Pennsylvania declined to participate in their survey.

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