Arctic Temperatures Plummeting

Temperatures in the upper Arctic are not only below normal, but are now dropping off a cliff into deep below normal territory.

The chart above shows three lines plotted: the freezing temperature of water (shown by the blue line), the average Arctic temperature in green, and the observed Arctic temperatures in red. It has been well established that the Arctic has been in cooler than normal weather over the summer, but it is only in the last week that temperatures have seriously dropped off.

A temperature analysis chart from August 14 shows a deep pocket of below normal temperatures in northern Greenland, and it appears this pocket is the culprit behind these very cold Arctic temperatures.

Continued below-normal temperatures in the Arctic would more than likely initiate an earlier fall, and possibly an earlier winter in the upper latitudes. Should the atmosphere cooperate, lower latitudes, like the US, could see an earlier fall in the form of colder weather as a product of these extraordinarily cold Arctic temperatures.

Andrew

Invest 92 Eyeing Mexico, Texas for Landfall

As I predicted would happen a few days ago, the tropical system over the Yucatan Peninsula is going to take a westward path and threaten Mexico/Texas in coming days.

The latest suite of model guidance agrees that Texas and Mexico are at risk of this storm making landfall in the next few days, although just how intense the cyclone ends up being is to be determined. Intensity forecasts for this tropical system indicate it has a chance to strengthen to tropical storm status prior to landfall. While warmer sea surface temperatures indicate this could happen, the general trend this year is for tropical systems to not strengthen when they are supposed to. Going with the trend, I anticipate a modest tropical system (meaning some rain, some wind, but NOT a tropical storm or hurricane) to impact either Texas or Mexico.

The HWRF model, a hurricane version of the WRF forecasting model, shows a strong tropical cyclone making landfall in northern Mexico, producing significant rain and wind. It is worth noting that the HWRF is consistently over-exaggerating the strength of any and all tropical cyclones, and thus this forecast is worth little. I put it here to show not only what appears to be the strongest forecast for this invest, but also just to show how weather models are not 100% reliable.

Andrew

New Developments Strengthen Argument for a Cold Winter Ahead

New and exciting data has been uncovered in recent days that not only has strengthened my analog set for the winter, but has also cut down on a good deal of uncertainty I had up until this point.

This image, put together by Accuweather Forum user Noreaster07, shows a total of five images. The top two images show temperature averages for the winter of 2012-2013 on the left, with the temperature average of the winters of 1982-1983, 1992-1993, and 2001-2002. Both images show a clear warm weather trend over the United States. Moving ahead to the second row of images, March-April temperature composites for this year (left) and the three aforementioned years (right) are shown. Oddly enough, there is another clear similarity between the images. On the bottom image is a composite of winter temperatures for 1983-1984, 1993-1994, and 2002-2003. If the similarity trend continues between these three years and the current year, this would only add to an increasing amount of evidence suggesting we could see a colder winter ahead.

But here's what really excites me: when compared, the winters of the fifth image on the portrait above are similar to my analog set in the mid-latitude atmospheric flow.

This image shows 500 millibar anomalies for the winters of 1951-1952 and 1962-1963 (left), which are my analogs for this winter, and the 500 millibar anomalies for the three winters shown in the last image on the picture at the top of this post. There are a few key things we see here:

1. Active East Asian Jet Stream 

You can see deep negative height anomalies in East Asia on both images in the above composite. This symbolizes the jet stream is under stress, thus increasing its strength in that area. From looking solely at the image above, it would appear pressure anomalies are below normal in East Asia, meaning more storms in that region. If you have been with this blog for a while now, you may recall the times I have brought up a correlation between storms in East Asia and storms in the East US 6-10 days later. If the tightening of the jet stream in E. Asia is due to a stormier pattern in that area, it is entirely possible we see a stormier East US. This stormier East US could also then lead to higher probabilities of Nor'easter's.

2. Ridging Pattern in Northern Pacific 

It is well established that the Bering Sea is a favorite place for the origination of sudden stratospheric warmings (SSW's), a phenomenon that involves rapid warming in the stratosphere that then allows unusually cold air to reach the surface and lower latitudes just a couple of weeks later. Last winter, we saw a magnificent SSW originate from the Bering Sea, and other warmings attempt to take place in that same vicinity. With positive height anomalies stationed over the Bering Sea, intrusions of warm air by these positive height anomalies into the Arctic are more easily accomplished, thus increasing the likelihood of SSW events. Both my analog set and the other three years are steadfast on strong Bering Sea high pressure, meaning the chances of stratospheric warming events are enhanced, thus leading to higher chances of cold weather.

4. Low Pressure in Eastern North America 

Both images show very strong low pressure anomalies across the Central and Eastern US. This comes as a result of the ridging in the Bering Sea/North Pacific and another significant high pressure anomaly in the Atlantic (for my analogs, it's over Greenland; for the other three years, it is in the north Atlantic). The most significant result of these negative height anomalies over the Central and East US is very cold temperatures, and these are seen in the last image on the picture at the top of this post, as well as in my analog set, shown below:

Andrew

Prospects of an Early Winter Quickly Rising

The prospects of an early winter arriving in the United States are rising, as model guidance and observed temperatures in the Arctic support a quick start to the season.

Model guidance is projecting snow cover to begin building over Canada in just several days, and intensifying towards the US/Canada border by the final days of September. Three of the four CFS ensemble members project snow cover extending across much of Canada by the end of September, but all four members are in agreement that snow cover will be building across Canada in just a week or two, and beginning its advance towards the United States by September

Aiding in prospects for an early winter is the continued observance of below normal temperatures in the high Arctic region. As the graph shows, observed temperatures have been strikingly below normal for several months now, and have recently dropped below the freezing level. If below freezing temperatures can be maintained, and the general below-normal temperature trend holds going through fall, I do not see why scenarios like an early snow pack building over Canada and Siberia are unfounded, and thus the idea of an early start to winter over the US is brought to light.

Just because this winter may start rather early does not mean the winter as a whole will be intense; recall the October snowstorm that hammered the Northeast just a couple of years ago, but then saw the rest of winter with below normal snow and above normal temperatures.

Andrew

Tropical Storm Likely to Hit United States; TX, MS, AL Threatened

It now appears that a tropical cyclone (most likely of tropical storm status) will make landfall on the United States. Among the threatened areas are Mississippi, Alabama, and Texas. Mexico is also bearing some threat of this cyclone making landfall in that country.

At this moment, it appears we will see development of this cyclone occur just north of the Yucatan Peninsula. All model guidance that is portraying TC formation does indicate it would begin in that region. From there, model guidance diverges into two clear paths: one takes the cyclone and hits Mexico or southern Texas, while the other path allows the cyclone to travel north and hit Mississippi/Alabama, and possibly a bit of Louisiana. I outlined the TX/MX landfall idea as the more likely one, mainly because of what happened recently over in Asia with Typhoon Utor. There is a theory that if a typhoon in the west Pacific does not curve away from land before landfall, a tropical cyclone in the Atlantic will also refrain from making a curve north, thus enhancing landfall potential. Since Utor did not make a curve north before hitting Asia, I anticipate we will not see a strong curve/shift north like the GFS is showing. Rather, the CMC may have the correct idea of a more west/WNW direction with this cyclone. It should be noted that model guidance is leaning towards the MS/AL landfall more than the TX/MX landfall idea, so please keep an open mind on both solutions; better to be safe than sorry.

Regardless of what happens, it is clear there is a substantial threat to life and property, as is with any tropical cyclone. I personally advise all those living along the coast of the Gulf of Mexico keep a sharp eye on this situation, but heed government notices first and foremost on this landfall threat if any are issued.

Andrew