Messy Midwest Thurs/Fri
December 19, 2012 1 Comment
Storm arriving onshore tonight will strengthen over the Plains Wednesday before slamming the Midwest with heavy snows.
Clues of our storm can be found on the west coast of the US. Note how the lime green height lines dip and form a sort of ‘U’ or ‘V’ shape. This forms our trough. Typically the center of low pressure will form a little south and east of the bottom of the trough, but this depends on what level of the atmosphere you are observing the trough in. Typically trough features are most recognizable in upper air maps (500-300mb), while the low is noted on surface maps lower in the atmosphere. Anyway, this trough will propagate east through the coming hours and our surface low will begin to take shape.
NWS has great confidence in where the heaviest snows will occur. Think they are on to something as models have been fairly consistent with the storm track. Typically for heavy snows, you want to be in that northwestern portion of the low circulation. This is where cold air is in place and moisture is fed up the warm conveyor belt into it. Here is a map showing current watches/warnings.
This coincides well with the modeled snow accumulations through the period. Below, the GFS’s latest shot at snowfall.
Winds will be nothing to sneeze at for this storm. This will likely be the main threat for southern Michigan. Warm southerly winds will be in place come Thursday morning before shifting as the low passes. Once the low has passed, winds will pick up and shift from the north. These winds will be cold and will coincide with wrap around moisture leading us to our chances at snow. Gusts to 45mph are not out of the question for Friday morning.
While lower Michigan is missing out on the brunt of this storm, should still be aware for the mentioned wind and any slick spots during the rain/snow transition. Rain will be the main precip type for many locations south of Grand Rapids and Saginaw.