1990-91 exhibiting incredible similarities to upcoming winter

The more I look at the winter of 1990-91, the better it looks as an analog for this upcoming winter. First thing to note is that it matches very well with our current QBO state. It is one of two years(the other one being 85-86) within 3.50 of our current 30mb QBO anomaly that also has a neutral ENSO state.

2013 30mb QBO numbers from Feb to Sept: -4.13 -0.23 3.12 8.36 14.25 17.89 21.01 21.36
1990 for the same time period: -6.78 -5.74 1.21 5.68 13.06 17.40 19.26 19.32


The Dec-Feb SST pattern also matches up very well with forecast SST setup from the ECMWF/CFSv2. Note the warmest ENSO anomalies are in nino 3 and 4 with very warm water east of japan. Cool water is positioned off the west coast which is where we are trending this year given expected troughiness.

1990-91 SST setup:

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Euro DEC forecast looks fairly similar with the exception of a warmer north atlantic setup. Would expect more blocking and higher heights near the canadian maritimes with this years setup. Wave breaking also favourd south of iceland.

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500mb heights that winter have more of a positive NAO look with a SE ridge and a -WPO/strong aleutians ridge.

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Another interesting note about that winter is the spike positive in the PDO in late summer and early fall only to see the index drop considerably during winter.
Jul to feb PDO: 0.27 0.11 0.38 -0.69 -1.69 -2.23 -2.02 -1.19 

Cold First Week of October Likely, Despite warm euro weeklies

The weather world has been buzzing lately about a very warm start to the month of october. Most people have been banking on the latest run of  the european weekly model, forecasting balmy conditions in the great lakes/northeast part of the u.s. I don't believe this will be the case, and will explain my reasoning in this post. 

A major -AAM pulse is currently underway which is helping boost equatorial easterlies and an alaskan ridge.

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We are seeing the EPO index respond to this in the short range with a major dive into -1 to -2 territory. This promotes warmer then normal temps across alaska/western canada with arctic air intrusions downstream, especially if this coincides with a -AO event.

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The GWO may be key to determining the weather pattern for the first week of october. Based on lowering AAM in first week of the month, a mean trough over the east looks more favourable despite a warm look to the euro weeklies. Heres the GFS forecast with a major drop in AAM by week 2. If this can coincide with a -AO/NAO, look out! Again, this type of evolution would help transport heat from the tropics towards the gulf of alaska therefore driving the -EPO and downstream pattern.

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GFS ensembles are picking up on this  pattern in 1st week of october with several members showing a pretty robust ridge in the west with troughiness downstream. So the message I am trying to send across is that we may see the potential for an indian summer in the west with another major cold shot for the great lakes and east. between october 1st and 8th. Get your winter gear out and get ready for the fall temperature roller coaster!

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QBO Invesigation

Staying on the topic of the QBO, I decided to look back at all years since 1979 that had a September 30mb QBO number within 5.00 of our monthly anomaly this september (21.36). These years also had to fall within 2 months of the westerly QBO peak. Keep in mind that all these years were in the westerly shear phase going into winter, which is where we are headed currently. Here is the corresponding 500mb pattern for the following Dec-Feb periods. 

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OLR anomalies have the MJO mainly in phases 5-8 for the DEC-FEB period.

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Precipitation

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North Pacific Pattern is Key

Couple important things we may want to keep an eye on over the next few months:

1. A batch of much warmer then normal SST's east of Japan favours stronger jet streaks over the north pacific. This sets up a +WPO pattern with zonal flow across Central/Eastern north america and a trough over Alaska/Pacific NW.
250mb Wind Speed and GPH forecast illustrate this pattern

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We need to see the GOA remain warmer then normal with cooling taking place across the bering sea and NW pacific. The ECMWF monthlies support this although the west coast cools some with the GOA warm pool shifting west.

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If we look at past torchy winters in the east we notice similar trends with a Ring of cold in the GOA and warm SST anomalies east of japan.
Sept 2011:

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The good news is, with the MJO currently over the W PAC, the tropics are responding over there with more recurving TC's helping to cool off the GOA/waters East of Japan. Obviously not the only factor to consider but something to keep an eye on...

A quick note on the QBO... we are quickly headed towards the +QBO peak and are expected to head into the westerly shear phase by winter which favours phases 7, 8 and 1 of the MJO.  This bodes well for winter weather lovers as it favours cold and snowy conditions over the eastern two thirds of north america.

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Winter Ramblings

Couple Interesting developments with regard to the GWO phase spacing over the last few months. Notice the gradual but significant shift to positive phases since june/july. The GEFS forecast continues this trend with propagation into phases 5-8 by late sept/early oct. 

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Definitely goes to show the significant recovery from what looked to be at least a weak la nina for a time in early to mid summer. 

The latest weekly SST departures valid sept 16th:
Niño 4 0.0ºC 
Niño 3.4 0.0ºC
Niño 3 -0.2ºC
Niño 1+2 -0.4ºC

With a neutral ENSO signal we will have to turn to other factors...starting with the atlantic. Here is the ideal SST setup for a -NAO in DEC-FEB.

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If we look at our current SST setup we notice a southerly displaced warm belt, positioned off the coast of NL and NS. Cooler SST's are evident south of greenland and iceland. This doesn't bode well for a consistently negative NAO and leans more towards a +NAO pattern in the cold season with a SE ridge.

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H5 anomalies from the past month illustrate this well. Will be interesting to see where we head in the fall.

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In terms of the pacific, +QBO la nada's or la nina's favour a stronger and northerly displaces bering sea ridge. With the GOA expected to cool off, this type of pattern keeps height falls east of the west coast with a SE ridge in place and wave breaking events/troughiness across E CAN, New England and the maritimes. This would keep the mean storm track across the great lakes with above normal precip in the west as well. The Mid ATL/SE would stay warm and dry in this setup. This is how I see the mean pattern setting up for the first half of winter. We should see more enhanced blocking in JAN-FEB and may even see a SSW event with the low solar regime in place. 2001-02 is a good example of how this can happen, despite a +QBO event. 

El Nino Looking More Likely... Implications On Winter Pattern

Starting to notice subsurface anomalies really warming up now with yet another push of warmer then normal anomalies towards nino regions 1,2 and 3 below the surface. 

Surge of warmth was caused by a Kelvin wave that passed through the west pacific in the first few days of september allowing SOI values to drop significantly.

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Euro and NMME suite staying in the el nino or at least warm biased neutral camp and have been pretty consistent for several runs now. With this type of SST profile, positioning will be critical as a basin wide or east based warm event does not produce the goods in the east.

Euro SST profile not ideal with core of warmth near 120W.

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In coldest el nino years we notice the core of warmth west of 130w. For example, 1963 in december was very cold in the east and had that type of setup.

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In 2002 and 1957 we have a basin wide nino in december and a very warm month across much of NA with the exception of the SE in 2002.

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Positioning of warm sea surface temperatures will be key... but could bear fruit if we see a favourable setup.

May Verification and June Forecast

May Temperature Forecast Verification:

Here was my may forecast:

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Actual temperature departures for may:

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For my June temperature forecast I am going with a cold eastern/central part of the u.s. Their are several reasons why I am so aggressive on the cold when CPC has equal chances for june. 

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1. Over the past few weeks we have been seeing wetter than normal conditions over the american midwest and western great lakes region. This means that when warm shots come racing out of the plains they will pack less of a punch then if the ground was already dry.

2. The MJO is headed into phase 2-4 over the next two weeks which favours a trough over the central and eastern part of the u.s. This will make it very difficult for temps to recover later on.

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3. Euro weeklies are strongly supporting a colder than normal june with the first 25 days of the month looking much cooler then normal in the midwest, great lakes and east with wet conditions along the gulf coast.

4. ENSO anomalies have turned much cooler in eastern ENSO regions relative to western ENSO regions. This will keep the core of the heat confined to the SW U.S and western rockies. I think B.C stays transient as systems move through and heights fall later in the month. Temps may end up slightly above normal.


It does look like we will see some very warm days in june across Ontario/quebec it just means that we will see more cloud cover and precipitation holding back departures in southern ontario. In eastern canada, northern ontario and the prairies temps look to average near to above average. This month should also feature above normal severe weather in the great lakes region with more clashes between warm and cool air masses.