Saturday, August 15, 2020

Very Dry Week Expected Ahead

After a cold frontal passage brought a line of showers to the Stateline on Saturday, the upcoming week will likely fall short on the rain that this month has been lacking.

Through Saturday, the month of August had brought rainfall to Rockford only six of fifteen days; rainfall was measurable only two of the six days. All but 1/100 of an inch of this month’s 0.52 inches of rainfall fell during Monday’s derecho event. This puts Rockford 1.76 inches short of the normal month-to-date rainfall total. This upcoming week will not be much help in catching us up either.

On Saturday, a cold front moved through the Stateline bringing scattered showers and even a few thunderstorms to parts of the Stateline through the first half of the day. Rockford in particular only received a trace of rainfall through the day. As the front moved off to the east, a high pressure system situated out to our west quickly advected plenty of dry air into the Stateline dropping our dewpoint by 10° in five hours.

In the northwest U.S., a very large upper level ridge will hold strong through the upcoming week. Sitting underneath the lee side of this ridge, several strong surface high pressure systems will develop over and move through the Midwest. This will keep most of the atmosphere over the Stateline relatively dry, especially down near the surface with 20+ degree surface dewpoint depressions forecast through Friday. High Pressure over the area will also keep the dynamics necessary for rainfall away keeping the rain chances through most of the week very low. The next good chance for rain doesn’t arrive until late Friday into Saturday as the axis of a negatively tilted midlevel trough moves over the Stateline and brings strong pockets of vorticity to the area after low and midlevel moisture will have recovered quite a bit. This will bring us a good chance for some scattered showers and possibly a few thunderstorms to kick off this next weekend.

 

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