WEATHERAmerica Newsletter, Saturday, July 1, 2023 at 11:15 P.M. CT; Longer Term Outlook

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Larry Cosgrove

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Jul 2, 2023, 12:28:37 AM7/2/23
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EXTENDED PERIOD FORECAST
(Between Day 11 And Day 15)
 
The Elongated Heat Ridge Will Dominate The Month Of July In North America And Eurasia
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CIMSS (2)
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TropicalTidbits.Com (Dr. Levi Cowan) (3)
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NOAA/PMEL
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NOAA/CPC
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HPRCC/University Of Nebraska (2)
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Environment Canada
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TropicalTidbits.Com (Dr. Levi Cowan) (5)
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ECMWF (3)
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NOAA/CPC

It is all about that heat ridge....

Even though a weakness has developed in the vast ridge complex stretching from the eastern Atlantic Ocean into Pakistan, all of the numerical models strengthen the elongated subtropical high and extend the westward edge of the ridging into California and Nevada within eight days from now. This set-up is important for any number of reasons. One is that at a time when upper westerlies are relaxing, a huge injection of hot, dry and dusty air from the Sahara Desert will follow the ITCZ impulses coming out of central Africa. That eliminates chances for tropical cyclone development. That same, arid cTw fetch will reach the southern half of the lower 48 states, bringing temperatures up, eliminating potential for diurnal convection, and capping the atmosphere in such a way that moderately high surface dewpoints will be accompanied by haze, smoke, and pollutants for major urban areas below the Interstate 70 corridor. And this type of pattern will last a while, too. CFS and ECMWF outlines have something similar showing up at 500MB into mid-August. Texas is going to get the lion's share of the heat waves through the rest of the summer.

Of course on the north side of this mega-ridge, there are shortwaves which originate in the broad upper disturbance over the Aleutian Islands and swing through an arc along or just below the border with Canada. Thunderstorms will form in groups across the northern Intermountain Region, dig somewhat through the Upper Midwest, Great Lakes/Corn Belt before exiting the USA over New England and the Mid-Atlantic. This is a situation somewhat analogous to the summer of 1992, and may eliminate the near-drought episode that is starting to break down over the Midwest and Northeast. While there may be occasional insertions of hot air, roughly the northern half of the nation will likely see near-to-below temperatures. The convection associated with each impulse and surface front will prove a deterrent to intense heat.

The El Nino signature across the, but Pacific Basin is well-defined, but showing signs of weakening in its western sectors. We will not know how the sea surface temperature array will play out for the cold months until after Labor Day. Often with this type of scenario, very hot and dry weather from California to Georgia and Florida will flip to a cooler, wetter arrangement with a stronger southern branch jet stream and the familiar "smile" lateral Rex ridging across southern Canada. I can warn you now that the dryness from Alberta to Quebec will likely accelerate this fall. So the fire and smoke hazards we have seen will need some form of winter cold to relax the incendiary concerns above the International Border.
 
Prepared by Meteorologist LARRY COSGROVE on 
Saturday, July 1, 2023, at 11:15 P.M. CT

Disclaimer: 
The previous statements are my opinions only, and should not be construed as definitive fact. Links provided on this newsletter are not affiliated with WEATHERAmerica and the publisher is not responsible for content posted or associated with those sites.

Copyright 2023 by Larry Cosgrove
All rights reserved.
This publication may not be reproduced or redistributed in whole or in part without the expressed written consent of the author.
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