Friday, January 23, 2015

Short Range Outlook (Made January 23, 2015)

This is the latest Short Range Outlook post, where the pattern for the next 0-7 days is addressed. This forecast is valid for January 23rd to January 30th.


500mb geopotential height anomalies (right panel) and means (left panel) over the last 7 days show a general ridging pattern across the western portion of North America, extending a bit into the Central US and southern Canada. This pattern resulted in generally mild conditions for much of the nation, particularly in the Plains region. This warmth was not as enthusiastic in the New England region.

Satellite analysis of the Northeast Pacific shows abundant moisture making its way onshore in the Pacific Northwest from as far west as Hawaii. This will lead to rainy weather in that region for the foreseeable future, while drier conditions should persist in the Southwest. Some of this moisture is associated with a system that will be moving into the Midwest and Ohio Valley over the next few days, dropping accumulating snow as it does so.
Instant Weather Maps

Model guidance sees the aforementioned piece of energy sliding southeast-ward as a weak snow-producing system. From the most recent NAM model, the heaviest snow would appear to fall in northern Indiana, central Ohio, and into the mid-Atlantic, with scattered snow also showing up in Wisconsin, Minnesota, Iowa, Illinois, and points east, all falling this Sunday through Tuesday. A different storm system looks to drop plowable snow in the Northeast in the same timeframe.

After this weak system moves eastward, model guidance sees another small storm system dropping into the Midwest, likely laying down some low-accumulation snows. Latest model guidance indicates this would be another 1-3" snow event.

To summarize:

- Heavy snow looks to impact the Northeast in the next four days.
- A weak storm system will drop from Canada and produce accumulating snow in the Midwest and Ohio Valley in the next four days.
- Following that storm, a weak clipper may lay down another 1-3" of snow in similar regions.