Category Archives: PHL Climate Forecasts

WEATHER OUTLOOK -COLD THANKSGIVING

A dip in the jet stream is predicted for the coming week, with  the coldest temperatures forecast for Wednesday night through Thursday night.

amplified jet
GFS Model Forecast for Thursday, (Thanksgiving) afternoon.

The extended range GFS and NBM (National Blend of Models) shows a high of about 32 for Philadelphia on Thursday!   Actually, that’s an improvement; the forecast dip was even more amplified just a few days ago.

A warm up and rain is expected next Sunday or Monday, then a return to colder conditions sometime during the following week.

I continue to feel we will have a colder than average winter due to the nadir in the sunspot cycle and a stormier winter as well, with plenty of moisture available in the southern jet stream from a developing El Niño in the Pacific.

I first made this preliminary climate prediction a few weeks ago.  Past information about the sunspot cycle’s influence on temperatures can be found here.

EARLY WINTER CLIMATE OUTLOOK

I received an email from a follower of this blog asking for my thoughts regarding the upcoming winter.   Here’s what I replied:

Thanks for the confidence you expressed in my forecasts. Winter weather seasonal forecasts are more about climate than weather.  Even the National Center for Climate Prediction doesn’t do too well with these very long range forecasts.

That said, I usually take a stab at the Winter Weather Seasonal Forecast towards the end of November.  By that time, any pattern that may become established will have revealed itself.

But if you want an early sense of things, the nadir in the sunspot cycle suggests plenty of cold air.  The current dips in the jet stream suggest a stormy winter.   And an expected appearance of El Niño in the Pacific suggests plenty of moisture.

So expect a cold winter with plenty of storms and plenty of snow.   That’s my best bet right now.  But things could change if the jet stream dips change over to the western side of the US.

Winter Climate Outlook for Philadelphia

It doesn’t take much climate science background to identify that this years’s current weather pattern is very different than the last two years.

While past winters were possibly affected by the diminished solar cycle peak and the random blocking patterns that set up for unknown reasons, one recognized climate influencer is the El Ninio Pacific Ocean  temperature cycle.  With current Paciific Ocean water temperatures at an extreme peak, the El Ninio will over-ride any other recognized patterns or climate “oscillations” that otherwise affect our climate.

The official NOAA Climate Center has predicted a warmer and wetter winter for our area this winter, based on the El Ninio, and that sounds righ to to to me.  Expect periods of very warm weather (the upcoming weekend a good example), but there will still be periods of cold.   (Hey, it’s winter.).    Expect mostly big rain storms, but a big snow storm could still be possible.

Right now, it appears that the warm pattern stays with us through the middle of December.  Current models suggest that the more recognizable winter weather cold temperatures arrive here about December 17th.

Madden-Julian Oscillation

Last year, the meteorological term that was in vogue was “polar vortex”, something that always exists but like a spinning top, can sometimes spin eccentrically off the main polar axis giving us bitterly cold weather.  As I noted in a previous climate forecast, this year looks very different.    The vogue climate phrase I expect to see this year will be the Madden-Julian Oscillation (MJO)

For the coming week, the large scale weather phenomenon that is causing all that rain on the west coast will give us warmer than normal temperatures.  This large scale climate phenomenon is associated with a certain phase of the Madden Julian Oscillation– warm moist tropical convection (thunderstorms) in the Indian Ocean and Pacific  that slowly migrates eastward and affects the US.   Most noticeable during lulls in the El Nino cycle.

This usually brings heavy rains to the west coast and can result in deep storms in the Eastern US as a result of a natural “wavelength” to the jet  stream.    This is what is speculated to be what’s happening with the heavy rains in California and the deep low that just affected us.  These phases last 30-60 days, so a wet and milder pattern will likely be with us for much of the remainder of this month.  The next “phase” of the MJO isn’t expected until late December or early January, so cold weather may return.  This phase of the MJO is simply a bias towards wet and warm and the East coast effects are less deterministic.