Posted at 5:00 PM on April 5, 2010
by Paul Huttner
Filed under: Rainfall
The latest trends in our Midwest weather system indicate that the more consistent rain bands may be sliding a bit to the south. That could mean less beneficial rainfall for parts of central and southern Minnesota, including the Twin Cities metro area.
The first wave with this system is lighting up radar with scattered showers Monday night. There may be a break in the action before the second, stronger wave moves in Tuesday.
Morning and midday forecast model runs are stretching or "shearing" this incoming upper low from north to south over the central plains. This usually produces a more elongated area of rainfall, and prevents deep moisture from being thrown up over the Upper Midwest.
Also, severe weather with clusters of thunderstorms in Iowa, Illinois and Indiana are "sopping up" some of the moisture before it can get dragged further north by the system.
The combination of these two factors may limit the amount of available moisture to generate widespread lasting rains in southern Minnesota. It still looks like the I-90 corridor may see a good soaking of anywhere from .50" to 1"+ of rainfall that extends down into Iowa and southern Wisconsin with this system. Areas from the Twin Cities to Redwood Falls may see somewhat lighter amounts; it's looking more like .25" may be the average that far north of the system. The latest trends indicate St. Cloud may see even lighter amounts.
Forecast models rainfall projections show a trend over the past 24 hours. Notice how the NAM model dropped predicted rainfall from about 1" to .3" in just one model cycle.(click on image for bigger picture)
Stay tuned and we will keep an eye on radars to see how far north the precip is able to make it Tuesday!