>July 2009 will down down in the books as record cold and record hot. Seattle witnesses it’s first high topping 103 degree along with other Pacific Northwest areas never seeing hotter than Wednesday was. while out east across the Midwest, Chicago will end July the coolest in 118 years and the first time in 139 years it’s peak high was just 86. In recorded history, there has been no July where the temperature has failed to get above 86 degrees. Many areas from the Dakotas to New York will end this month as 3rd coldest including New York City’s Central Park where the high failed to rise above 90 degrees.
I made a statment back on July 17th on this blog, that New York would fail to make 90 for the month of July which ended up being correct, however I did not think that would also happen in Minneapolis and Chicago. It has been remrakbly chilly across much of the country “east of the Rockies”. West of the Rockies it has been hot, some 2-4 degrees above normal but the cold out weighs the warm and this month will likely end cooler than normal. A big dip in the jet stream has allowed pockets parcels of cool air to rotate down into the base of the persistent trough hanging deep into the eastern half of the country whilst the build up of heat south of the jet has been evident across the south, cooling off further east across the Deep South by mid month and graually cooling east to west through the progression of July. The ridge was continusously building across the Desert Southwest whilst the locked trough was deep and impossible to remove throughout the month. I do believe the reasoning behind why the Pacific Northwest got as hot as it did was simply because of the atmosphere set up across the country. Trough of low pressure over the east, ridge of high pressure over the west, jet stream in between, this piling up and heat west of the jet (across the eastern Rockies) forced compressional heating through the atmosphere over the West, with nowhere for the air to go, as pressures lowered to the east, pressures where forced to rocket up and over the Pacific Northwest, intensifying the high over the PNW, clockwise flow pulling hot air towards the coast, had to cross the Cascades and in doing so, downsloped and further heated an already sweltering air mass. The east, offshore flow dried out the atmosphere, oushed out of the marine influence and unlimited heating occured. But this was helped along by the squeezing of the cold air which was nudging up against the hot dome that became elongagated north to south up the western half of North America and pushing 90s into the Arctic Circle and forced thermometers to top 100 in Seattle and stopped at a remarkable and historic 103 degrees, setting a new benchmark. Portland fell short of it’s record of 107 by topping 106. Portland’s location within the Willmette valley means it can heat up easier, more land locked and effected by downsloping compressional heating, allows it to be hotter than Seattle which sits beside the cooling Puget Sound.
NEW YORK CITY TO NOT HIT 90 IN AUGUST EITHER!
I do believe it is possible and I am putting this out there now!!! New York’s Central Park may not hit 90 throughout August and may hit by September before a fast start to winter bgins in October.. Minneapolis and Chicago, though may have a better chance of seeing 90, may not either as the trough hangs more over the Midwest to central Plains.
LA NINA AND PAST TWO WINTERS TO BE BLAMED ON COLD SUMMER, COLD SUMMER TO BAME FOR SEATTLE’S 103..
Not being for a cold winter, caused in part by cold PDO, it’s reactive response being the La Nina of 08, we have seen near record cold May in Canada and holding on longer to Hudson Bay ice and upper air streering pattern as kept the refrigerator on non-stop over the eastern Canadian Arctic, keeping a massive cold pool across the eastern half of the continent. This cold pool, southerly jet stream has kept heat building in a more confined area of the souther tier states from Georgia to California, this heat had nowhere to go but up the western passage! West Coast of North America bringing warm, dry summer to Alaska, British Columbia and areas far north. The deepening of th interior cold pool and pumping of the western ridge, created squeezing, fiction and therefore enhanced heating of the air further north that normal. Bringing record heat from Phoenix to Barrow.

Thanks for reading.
-Mark