Monday, November 04, 2013

Tropical Influence On Plains Midwest Winter Storm

Tropical Storm Sonia made landfall last night in Mexico, providing soaking rains to the Mexican Pacific coastline and the Baja as it churned northeast for a final landfall.  Its moisture will be one part of the ingredients in a developing storm system that will organize in the Rockies later today.

The other piece of energy for the storm moved onshore yesterday to California and is now working through Nevada. Between it and Sonia's remnants, the two pieces will come together in Colorado to fuse an early season winter storm for the Plains and Upper Midwest.

Tropical Storm Sonia (bottom, left) will provide a moisture source on a developing winter storm in the Plains and Upper Midwest. The other source of energy is a disturbance in Nevada (far left, above).

Winter Weather Advisories and Winter Storm Watches are out in Nebraska and Minnesota for this storm system. While an early season winter storm is not unusual, the direct connection from a decaying tropical system isn't something you usually get with winter storms but it does happen on occasion.  Unlike Sandy's deposit of snow in the Appalachians last year, Sonia will be little more than a moisture source for this Plains storm by the time the moisture gets pulled north into the US thanks to the amount of real estate the tropical system will traverse and weaken across and not the primary "cog" in the snow making engine. A few hurricanes on the Atlantic side have produced snow in New England and Upstate New York after transitioning to nontropical after landfalls, including storms in 1804 and 1963.

By Tuesday night, snow will spread across Minnesota and Wisconsin from a developing storm system that will have some tropical moisture ingested into it.

All that said, the developing storm system will gradually work its way east. We will not see snow from it as the low pressure center tracks through Southeast Canada, but it will provide the next shot of rain on Thursday in the region.