15.11. Cyclone Tracks

The track of a cyclone is very important as the exact track can make or break a forecast of precipitation. For example, a very powerful mid-latitude cyclone moved up the East coast of the U.S. in March of 1993. Three different weather models had three different tracks and the forecasters had to pick one to determine their forecast. They chose the path that went along the coast, and the storm followed that track. This storm is now known as the Storm of the Century. Had the storm tracked more inland or went further out into the Atlantic Ocean; the storm would not have had the same impact across the U.S., placing the precipitation either more inland or further out to sea.

There are three to four primary tracks of mid-latitude cyclones across the continental U.S. This is not to say that all mid-latitude cyclones will follow only these tracks, but that most cyclones originate and travel well-defined corridors across the country. The three primary tracks are: Alberta cyclones, Denver (Hooker) Cyclones, and East Coast Cyclones (Fig. 15.7).

Fig. 15.7 Dominant cyclone tracks across the continental U.S. for typical winter patterns.

So, what’s in a track?

The track that a cyclone takes is the first opportunity you have to determine what type of weather a particular area will have as a cyclone moves through. If the track of the center of the storm is going to the north of your location, then at some point that location will be in the warm sector of the storm. This will obviously affect any temperature forecast for the area, but it will likely also play in your precipitation forecast.

Snowstorms

For a location to experience a strong snowstorm, the track of the surface low must be to the south (but not too far south). For the Valparaiso area, the storm track most likely to allow for a substantial synoptic snowfall would be the Denver cyclone track. This track will typically ingest a lot of moisture from the Gulf of Mexico region, transport it northward and if the cyclone tracks to our south, then we are in the prime territory for snowfall. However, if the track goes through Chicago, then Valparaiso will get into the warm sector and have rainfall as our primary precipitation. Our only hope for snow would be after the cold front passes and the area is under any wrap around precipitation.

Alberta Cyclone

Alberta cyclones are generally harbingers of cold to extremely cold air for the upper-Midwest. They can bring snow, although snowfall totals are generally small due to a lack of sufficient moisture and very cold temperatures associated with the cyclone. These storms can produce very strong pressure gradients and thus very strong winds.

Denver Cyclone

This is our most likely heavy snow-producing storm. Although the track will tell the tale, if a given location is 100–200 km north of the cyclone track, then it will be in position to receive snowfall. If a location falls to the south of the forecast cyclone track, then any snowfall will likely be minimal.

East Coast or Gulf Coast Cyclones

If these cyclones track directly along the coast, they will have an ample supply of moisture that will feed into the storm. Depending on the time of year and exact temperature structure, there may or may not be substantial snow associated with this cyclone. Strongest precipitation is often along the cold front or within 100–200 km of the track of the cyclone (on the poleward side). Gulf coast and East coast cyclones generally do not give any precipitation to the upper-Midwest region; however, cold air will usually come into the region with a strong cyclone following these tracks.