Will Cold Air Return After the Late February Warmth?

The stubborn southeast ridge threw a wrench in our winter temperature and snow outlook for Cleveland and the Ohio Valley (more on that next week). We anticipated it to stay further east It has remained very strong throughout winter driving many panhandle low type storms along with temperatures recently to levels only reached a few times since record keeping began in 1871.

The stretch of warmth in Cleveland will more than likely end up being the warmest 11 day winter stretch ever!  This February stretch is similar to a warm February stretch back in 1976 and 2000. Notice the widespread nature of the warmth back in those years.

Looks similar to this stretch...

Yet California keeps getting pounded with heavy rain/snow as the very strong Pacific jet stream continues. Reanalysis of vector wind anomalies at 300 mB since December 1st (3 day running average). Pacific jet is through the roof strong. No sign of the ominous western ridge which was dominant over the last several winters.

The MJO strength increased significantly since early February to very high amplitudes into Phase 6,7 and 8 territory.

Phase 7 and phase 8 in February with high amplitudes tend to favor warmth east. Yet look at Phase 8. It tends to favor cooler temperatures east (middle chart below). So even with a very strong MJO the temperatures can be highly variable. What I find interesting is that the Phase 1 temperature composite (far right map below) looks very similar to the overall pattern since this current warm up began.

The chances of this February finishing out as the warmest ever in Cleveland is climbing fast.

Will colder air return?  If so, how strong?

To answer this we look at the Pacific teleconnections to start March. I reference my quick cheat sheet so that I can visualize the pressure regions in question.

PNA is heading sharply negative
EPO is heading positive/neutral
WPO is heading negative (strongly negative)

Strongly negative WPO during the first week of March

What do these teleconnection levels mean for our sensible weather?  Historic temperature composites for each of these indices (PNA,WPO,EPO) in March mean below normal temperatures across the northern states centered over the Corn Belt and High Plains. The Computer models are also depicting colder air (see graphic below, lower left) centered across the upper midwest/west to start March with above normal temperatures across the eastern US and deep south.

While we should anticipate short-lived cool intrusions across the Great Lakes, temperatures overall will average out near the 30 year average (see lower right graphic) for the first week of March.  For Cleveland, daytime average high temperatures for March are in the lower 40s. 

Long range teleconnections for the middle of March show some colder signs centered central US and west. Something to watch over the next week.

The South Oscillation Index (SOI)--changes in the pressure patterns in the tropical Pacific Ocean (click here for more on the SOI and here)--shows rising pressure in the central US March 10-13th after the central US trough slides east March 7-9th.

Will the weak trough be a more permanent feature over the Great Lakes or will a warmer ridge develop by the 3rd week of March?  The answer will be apparent in both the SOI changes. The teleconnections will reflect the changes by the end of next week.

Outlook For The Rest Of Winter? Written January 19th/Updated Feb 9th

Yes. It's a catchy title that probably evokes many suspect responses.  Let me explain my self:

Big cool down late this month/first week of February followed by a warm up by mid month February per the Bering Sea Rule which dictates ridge over the Bering Sea correlates well to eastern US ridge roughly 16-18 days in the future.





The GFS shows this ridge evolution quite well.

February 9th Update:

BSR verification (forecast left panel with actual heights right) for the period above looks pretty good.

This warm up may be the final nail in the coffin shutting down arctic cold for good this winter. Why? Check this out...how much snowfall did we get from 3rd week of February to start of spring in 10 historically cold winters in Cleveland? Not much...

Winter Pattern Unrelenting: More Arctic Cold

Our winter weather outlook back in late October featured a below normal temperature (much colder winter) with above average snowfall.  Given the weak central based El Nino, cool pool in the northern Pacific, warmer west coast and warmer east coast, a stronger southern jet stream phasing in with the polar jet to the north driving big snowfalls from nor'easter type storms in New England shouldn't be surprising.

The areas of the ocean that went into our winter outlook are circled in red. All pointed to colder than normal temperatures in the east.

This is different from last winter when the warm west coast cool of ocean was located in the north central Pacific near the Gulf of Alaska. The central based El Nino (Modoki) hadn't developed yet.

I want to emphasize that these warm and cool pools aren't and weren't the only drivers of our last two winters. But they are significant. Here was our initial best match as we formulated out winter weather outlook (December through February temperatures) back before Halloween.

The overall pattern remains very cold. More cold this weekend--Polar Vortex type cold!

Well below zero across much of the northeast Friday and especially Sunday morning. Even Florida will see lows in the 20s Sunday morning (February 16th) from Jacksonville to Pensacola. The orange crop might take a hit!

Below zero wind chills will reach northern Georgia and the Carolinas with -20 to -30 chills across the Great Lakes.

Here we are in mid February when the cold usually starts to retreat as the first pushes of spring emerge across the deep south. Will the cold air break sooner or later?

The often overlooked Canadian model shows the trough east/cold east continuing through the end of the month. The other models show this too.  However, the trough is retrograding back west a bit. This would shift the cold into the Great Plains by the end of February.

Cold Pattern thru end of February

In droughts, extremely hot conditions will feed off of the extremely dry air above the dry ground. This creates more evaporation which feeds the heat. This chain reaction is very hard to break. In perpetually cold patterns like this, the drivers are very strong and very difficult to break. The cold air can feed the upper air pattern reinforcing the trough in the east and cold/ridge and warmth in the west. In essence, the overall pattern remains stuck.

Good news is that heading into March even during the coldest Marches in Cleveland, 60+ degree warmth shows up by the middle of the month.

That said, the southern branch of the jet becomes very active in March. This could lead to a few more panhandle type storms in March which always have potential for reach Ohio.  Stay tuned.

Digging Deeper For Signs Of The Next El Nino

After reading several posts which posed the question of whether a "Super El Nino" will develop this summer, I wanted to find more data to shed light on what to look for in the upcoming weeks. These articles have sited sea surface temperature comparisons to 1997 both on the surface and below, ocean heat content, the building Kelvin Wave and subsequent changes in atmospheric winds.  All seem very valid. Let's review:

Comparing the sea surface temperatures on March 24th of this year to 1982, 1997 and 2002 (a weak El Nino year), each shows some warming in different locations at least on the surface. I circled the area in question in red. This is why we can't use a two dimensional sea surface temperature map as the only El Nino indicator.

 

Ocean Temperatures have been climbing in the western Pacific over the last 30 days. Notice the bubble of warmth between 100 and 200 meters.

Sub surface heat continues to build since the beginning of the year (see above). It compares very well to the onset El Nino of 1997. The Australian Bureau of Meteorology shows this very well.

HUGE spike in near surface ocean heat last 4 weeks

2002 was a weak El Nino year. The subsurface heating was nowhere as warm.

Comparing the sea surface temperatures on March 24th of this year to 1982, 1997 and 2002 (a weak El Nino year), each shows some warming in different locations at least on the surface. I circled the area in question in red. This is why we can't use a two dimensional sea surface temperature map as the only El Nino indicator.

The Southern Oscillation Index (Pressure index comparing sea level pressure at Darwin, Australia to Tahiti--30 day monthly moving mean) suddenly dropped into heavy El Nino territory.

Yet one index that blends together BOTH the changing ocean characteristics and the atmospheric conditions above it hasn't caught onto the idea...at least yet. Interestingly I haven't found much mention of this. This is called the Multivariate ENSO Index. The index includes several elements into its index: Sea surface temperatures, wind speed and direction, sea level pressure and temperature along with total cloud cover/fraction of the sky. Details are here on ESRL SITE.  Similar to the ONI Index, the MEI Index is calculated using overlapping 2 month periods. Since it takes into account many other atmospheric variables, the El Nino or La Nina signature may lag a bit compared to the others But in my opinion, it gives a better overall representation of the ENSO state even though it might be late to the party.

So far, the MEI is far ahead of 1982 and 1997, yet no positive numbers have shown up. Remember that The MEI is an overlapping bi-monthly indicator. So when the April update comes out (probably the first week of April), it will illustrate the conditions (ocean and atmospheric) for the FEBRUARY-MARCH overlap. If a  significant El Nino is truly developing, a SIGNIFICANT JUMP in the MEI would indicate it THIS SPRING as it did in 1982 and 1997. Check out the chart below for the past trend.

Be careful, the 1986 and 2002 MEI trends were SIMILAR to this year. Those years were weaker El Nino years.

Notice the MEI trends in 1986 and 2002.  Where will the MEI end up this summer?

So what's going to happen? Will the MEI match up with the MEI indices of the past El Ninos circled in black above. Will it mirror 2002 or 1986?

How will this effect out summer weather? 

The next 6 weeks will tell us a great deal.