Below-Normal Temperature Pattern Continues: Coldest Early October High Temperature Since 1915October 7th, 2012 at 8:49 pm by Chad Evans under Chad's WLFI Weather Blog
COLDEST PRE-OCTOBER 10TH DAY SINCE OCTOBER 8, 1915…….
We still have not really broke out of the below-normal temperature regime that gave us the cooler-than-normal September. This early October cold is pretty unprecedented. It reached just 46.4 degrees at WLFI today (after 80 Thursday)…………that’s it. Purdue crawled to 47. There have been some other years so unusually cold in early October before the 10th. This was record-breaking cool day for the date. It just isn’t cold here, it is record cold over much of the central U.S. (after a record hot, dry summer).
Early October 1935 was chilly with 3 freezing nights of 30-31 before October 8 & highs of 52 on October 4 & 50s October 3-7.
1987 was chilly early with upper 40s before the 10th, but 1915 was even cooler. The high temperature October 8, 1915 was 44 & 45 on October 6, 1873 at West Lafayette/Lafayette.
Record low temperatures were broken all over the Plains this morning with 15 at Sioux City, Iowa beating the old record of 23 degrees by an astounding 8 degrees!
Purdue University Airport 47
Indianapolis Executive Airport 48
Grissom Air Reserve Base 49
Indianapolis International Airport 51
WHAT IS GOING ON WITH THIS CHILL? WHERE’S THE WARMTH?
So what is going on? Why did this happen & where’s the 80s?
It was warm everywhere but here in late, late September-early October, but now nearly everyone is chilly (other than the western 1/4 of the U.S.). The heat has been west in September & now way to the west.
It has been incredibly active with typhoons in the western Pacific & several of these have hit Alaska as intense storm systems (extratropical storm systems). 3 of these strong systems produced a profound deepening of the upper jet very early in the fall. This very impressive buckling, combined with weakened polar vortex has allowed the cold to drop south. Also, recently very extreme upper ridging has moved northward into Siberia & Alaska, further enhancing the southward movement of cold.
WHY SO COLD EARLY…………..CHANGES TO LONG-RANGE FORECAST?
So, why so cold early? Why NOAA 180 to now colder-than-normal projection for most of U.S. in October after warmer than normal for most of U.S.? Well, I really think the blame lies in 3 typhoons & now Siberian/Alaska upper ridging. Also, am I going to change my fall outlook, too? No. Early October is definitely wrong in the outlook & I certainly did not see cold wave of this magnitude to impact early October. I saw cooler-than-normal September, but not October.
The winter forecast is done is there is no going back. I keep it status quo. Analog data really had a strong correlation to pretty warm, dry weather in October & normal winter snowfall (21″) with bit above normal temperatures, so prefer to stick with that.