Significant Weather Observer Program

 WEEKLY WEATHER DISCUSSION

written: 8/21/14 

Here is the latest U.S. Hazards Outlook issued by the Climate Prediction Center (CPC): http://www.cpc.ncep.noaa.gov/products/predictions/threats/hazards_d3_7_contours.png

A pronounced shift in the upper-air pattern is currently underway across North America.  After a spring and summer dominated by deep troughing over eastern Canada and the Great Lakes, a strong ridge of high pressure is building across the Deep South northward into the Midwest.  This is going to allow the hottest weather of the entire summer to arrive over the upcoming weekend, with high temperatures reaching the lower to middle 90s from Friday, August 22nd through Monday, August 25th.  With dewpoint temperatures hovering in the lower to middle 70s, heat index values will routinely rise to between 100 and 105 degrees during the period.  Meanwhile, several rounds of convection are expected along the northern periphery of the upper ridge, primarily impacting locations from northern Iowa eastward into the southern Great Lakes.  One cluster of showers and thunderstorms may skirt across north-central Illinois along and north of I-74 tonight (August 21st), while another may occur in basically the same area during the night of Friday, August 22nd.  After that, storm chances will be slim to none through early next week before the ridge gradually breaks down and a cold front arrives from the northwest.  At this time, it appears the best chance for widespread rain will hold off until next Wednesday and Thursday, followed by a return to cooler conditions by next weekend.       

NOTE: This weather discussion will be updated weekly (usually on Wednesday or Thursday) 

 


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