2013-2014 City-by-City Winter Forecasts: Springfield (MO), Williamsport, Detroit, Wichita, Baltimore

Springfield, Missouri

Temperature: Slightly Below Average
Precipitation: Above Average
Snowfall: Slightly Above Average
Confidence: Average

Williamsport, Pennsylvania

Temperature: Slightly Below Average
Precipitation: Average
Snowfall: Slightly Above Average
Confidence: Average

Detroit, MI

Temperature: Below Average
Precipitation: Average
Snowfall: Above Average
Confidence: Slightly Above Average

Wichita, KS

Temperature: Average
Precipitation: Slightly Above Average
Snowfall: Average
Confidence: Below Average

Baltimore, Maryland

Temperature: Below Average
Precipitation: Slightly Above Average
Snowfall: Slightly Above Average
Confidence: Slightly Below Average

Long Range Lookout: Rex Block in West Means Warmth for East

This is the first Long Range Lookout for the 2013-2014 fall, winter and early spring season. These posts will be issued each Wednesday afternoon, and if information arises that has a substantial effect on the long range, a special edition of the Long Range Lookout may be issued on the same day.

Long range ensembles are in agreement of a Rex Block setting up over the west coast of North America. The European ensemble set, shown above, projects negative height anomalies being positioned over the Pacific Northwest and southwestern Canada regions, with a corresponding positive height anomaly arising in northwest Canada and southeast Alaska. This is a classic example of a Rex Block, where negative height anomalies (low pressure) set up south of positive height anomalies (high pressure). To the east of this Rex Block, a few things can happen. If the low pressure system is angled correctly, negative height anomalies may stretch diagonally from the northeast of the low pressure system that is in the Rex Block. Another option is a zonal flow pattern, which means the jet stream is not wavy (in turn creating few opportunities for large-scale temperature anomaly patterns, negative or positive). The option we will most likely see in this situation is where the low pressure system in the Rex Block forces high pressure to set up downstream of the blocking pattern. In this case, the high pressure system would set up across south central Canada and the Great Lakes, as the ensemble set predicts above.

I expect this ridging pattern across south Canada and the Great Lakes to end roughly 3-5 days after it starts- this should not be a long-term event. The reasoning comes from an expected rising Pacific-North American index (PNA), which would allow for the departure of low pressure from the West, possibly shifting to the East. Remember that the negative PNA involves low pressure in the West and high pressure in the East, with the opposite true in a positive PNA. I have little doubt in my mind that the negative PNA we see in the projected teleconnection chart above is due to the negative height anomalies shown on the European ensembles image at the top of this post. On the right side of this image is the projected North Atlantic Oscillation over the next couple of weeks. The positive NAO pattern will be weakening to a neutral NAO, and could go to a negative NAO by the three week timeframe from today. The negative NAO encourages cooler conditions over the Central and East US, and the positive NAO we will be seeing in the next several days is a reason of why above normal temperatures are expected. The Rex Block pattern will not help matters.

Andrew

Who Could See an Early Snowfall?

Light Blue: 25-50%
Dark Blue: 50% <

I believe the Upper Midwest, Central and Eastern Great Lakes will encounter an early snowfall for the upcoming fall and winter seasons.

As the chart above shows, I have highlighted much of the Northern Plains, Midwest, Ohio Valley and Northeast for the risk of an early snowfall event. I have put these areas in a 25-50% chance for an early snowfall. The states of Minnesota, Wisconsin, Michigan, northern Ohio, northwest Pennsylvania, New York and portions of the far Northeast will have above a 50% chance for an earlier than normal snowfall event. This comes as a result of what could be a favorable pattern for colder weather to hit the nation as we head into fall. Should a storm system come along in the midst of this cold air, it is very possible that a snow event could come about.

Long range forecasts for the Arctic Oscillation show a definite negative trend for the index as we head through fall and even into early December. The graphic above shows this long range forecast by today's four CFS ensemble member's forecasts for the AO, as well as the forecasts from yesterday's four CFS ensemble members. These eight forecasts average out to a decisively negative phase throughout the fall and into winter. I have little doubt that this forecast will not verify as is shown above, but it is possible we see enhanced chances for a prolonged negative AO pattern. If such a situation were to arise, the risk of an earlier than normal snowfall would rise.

Andrew

Another Model Joins the Cold Winter Prediction

Another weather model has joined the ranks of those predicting a colder than normal winter across a rather large portion of the country in coming months.

This is the Constructed Analog, or CA model from the Climate Prediction Center. It projects positive temperature anomalies to develop across the Bering Sea and Greenland areas, which may indicate positive height anomalies (high pressure) in those regions. For all intents and purposes, let's assume high pressure anomalies do exist in these two regions of positive temperature anomalies. This then leads to colder than normal temperatures flowing southeast from western Canada, spreading across the Plains, Midwest and even towards the Gulf Coast. This is actually not that far off from other forecasts made by other models, and this strengthens the argument for a colder than normal winter.

500 millibar height forecasts for the December-January-February period basically confirm the assumptions we made earlier in this post with the temperature anomalies. We see persistent positive height anomalies across the northern Pacific and Bering Sea. This is a very good sign for the chances of stratospheric warming events, which, if the atmospheric pattern is right, can allow for frigid air to move into North America. Multiple forecasts have been indicative of this positive height anomaly presence in the North Pacific, and the CA model's projection of this factor only aids in its credibility. We also see an elongated positive height anomaly swath across eastern Canada, Greenland and into northwest Europe. This is supportive of the negative North Atlantic Oscillation phenomenon, which permits a flow of cold air and enhanced coastal storm potential mainly in the Northeast, but the cold weather can spread across a wide portion of land east of the Mississippi.

So what does all of this mean? The long range models seem to be coming together, suggesting that a cold winter may really be on the way. I've been seeing more and more evidence that such a winter may be unfolding in just a few months, and this new model projection only increases my confidence.

Andrew

Medium Range Forecasts Show Snowy Siberia

The latest snow cover projection over the next 192 hours has been raised to an increase 1.35%, as the fall season takes hold over the Arctic Circle and Siberia.

For days and days on end now, the GFS model has been projecting substantial increases in snow cover over a 192 hour period for the Northern Hemisphere. In the last few days, it has been showing increases over 1.00%, and the last several GFS model runs have seen increases above 1.10%. These snowy forecasts for the Arctic could bode well for the historically-accurate October Siberia Snow Cover/ Winter AO correlation, introduced by Judah Cohen.

If we do see snow cover continue to rise substantially beyond September and through October, we may be able to break through into positive snow cover anomaly territory. If we can do that in October, it means we may see colder weather for the United States. If you're a warm weather fan, you want to pray October sees well below average snow cover in the Northern Hemisphere. For you winter weather fans, you want to see this snowy trend continue for another two months or so.

Andrew