UNUSUALLY STRONG LATE SEASON WARMTH FORECAST TO DEVELOP OVER THE CENTRAL U.S. PUSHING CHICAGO TEMPS TO NEAR 90 THIS COMING SUNDAY, MONDAY AND TUESDAY—INTERESTINGLY, A PACIFIC TROPICAL STORM/TYPHOON AND ITS REMNANTS HEADING TOWARD ALASKA MAY PLAY A ROLE IN DEVELOPING THE MIDWEST NEAR RECORD WARM AIR DOME ALOFT. 

Our planet’s weather is inextricably linked. What happens at distant locations in the northern hemisphere can have fairly immediate effects here. THE STRONG WARMING predicted in the coming week–with the potential of near 90-deg temps Sunday, Monday and Tuesday–is a perfect example.

A northbound Pacific Tropical Storm–“MERBOK”—is to sweep toward the Aleutians and western Alaska in coming days. Tropical systems like that are giant heat machines and they bring warmth north with them. As warmth sweeps north into the Gulf of Alaska, a ridge in the jet stream (i.e. a “northward buckle” in the upper wind field) is to develop aloft–and if our computer model forecasts prove accurate, a deep trough (i.e. southward dip in the jet stream) will develop in response over the Western U.S.–good news for that area which has suffered through record heat and serious drought. The development of a trough aloft there could signal much cooler and unsettled weather which may bring rains–even high elevation snows. BUT THE APPEARANCE OF A TROUGH IN THE WEST is to pump up a near record late season warm dome over the Midwest. In that predicted warm air dome plus a well-developed southwest flow into the Midwest from the Gulf of Mexico which is to lead to unseasonably warm temps.

Record highs already on the books from Sunday, Monday and Tuesday are in the low 90s. We could get close to those and will watch with interest how this pattern change ends up developing. But I’ve included a set of high temp forecasts and also a 5-day temperature departure forecast map which lays out the area expecting above normal temps. The fact is, daily average temps in Chicago are likely to fall in the 8 to 16-deg ABOVE NORMAL range from Thursday of this week through Wednesday of next week. A downturn in temps follows later next week—but at the moment, the expectation is temps will STILL COME IN ABOVE NORMAL later next week–just NOT AS MUCH ABOVE NORMAL.

The graphics I’m posting illustrate where Tropical Storm “Merbok” is now (in the center of the Pacific) and where it’s predicted to go. I’ve even included a satellite image of Merbok off Japan’s Himawari weather satellite. Also included are forecasts of the potential track of Merbok, including a spaghetti plot of the tracks predicted for Merbok and two other typhoons headed toward the east Asian coast.