WEATHERAmerica Newsletter, Saturday, July 22, 2023; Longer Term Prediction

81 views
Skip to first unread message

Larry Cosgrove

unread,
Jul 23, 2023, 12:42:55 AM7/23/23
to weather...@googlegroups.com
EXTENDED PERIOD FORECAST
(Between Day 11 And Day 15)
 
The Analogs Are In: 1976, 1980, 2009, and 2011; Texas And Southwest Swamped By Heat, Great Lakes, Eastern Seaboard Relatively Cool With Thunderstorms
image.png
image.png
image.png
CIMSS (3)
image.png
image.png
image.png
TropicalTidbits.Com (Dr. Levi Cowan) (3)
image.png
NOAA/PMEL
image.png
NOAA/CPC
image.png
IRI/Columbia University
image.png
image.png
HPRCC/University Of Nebraska (2)
image.png
Environment Canada
image.png
image.png
image.png
ECMWF (3)
image.png
image.png
image.png
image.png
image.png
TropicalTidbits.Com (Dr. Levi Cowan) (5)
image.png
NOAA/CPC

In my career as a synoptic meteorologist, I have found that analog development, where the current temperature pattern, upper air and general character of weather is compared to previous years, can be a great help in predicting the outcome through the rest of the season and the start of the next period. As mentioned in the title, 1976 (500MB and precipitation array), as well as 1980, 2009, and 2011 (temperature scenario) provide significant clues for the ASO and NDJ terms. You may find some of the possibilities surprising.

The most significant feature is the huge heat ridge that has been shifting back and forth from California to Texas. Aside from occasional linkage with the Bermuda High, the CFS and ECMWF model series seem to keep that alignment going through Labor Day. The North American ensemble platforms, for what it is worth, have done the best job this summer so far in predicting the main features and surface weather. The main idea is that the ridge set-up will flatten out, slowly, as a split flow starts to set up in September and October. But some sort of +PNA ridging may remain in western Canada, which leads to the possibility of storms undercutting the potential blocking signature. This is an El Nino, after all, so a southern branch moisture expression is likely. And if you have high pressure in the Northwest Territories and Alberta, cooler values would be drawn southward as we advance into fall.

The tropical cyclone potential seems to be decreasing in the Atlantic Basin. For one thing, there are a lot of upper westerlies visible on water vapor imagery across the Atlantic Basin. If we are going to see any chance for a significant named storm or hurricane, the Saharan heat ridge must expand westward and develop gaps in its structure. That might stop the constant influx of hot, dry and dusty air that is seen now. You can have all the Invest speculation you want (and the ITCZ is very active across equatorial Africa), but if wind profiles aloft offer shearing and cTw values are inhaled into the impulses, you will not see further convective organization. You might have freak cases like Don in the middle of the ocean, or perhaps a diffuse frontal structure or rogue wave. But is that going to create the hyperactive season that you read about in broadcast and social media. Because surprises can occur, I will stick with the 13 named storms, 5 hurricanes and 1 major cyclone call for now. That said, a reduction in that prediction will be forthcoming if I do not see deep mean easterlies reach the Caribbean Sea and Greater Antilles by August 1.
 
Prepared by Meteorologist LARRY COSGROVE on 
Saturday, July 22, 2023 at 11:45 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.
Reply all
Reply to author
Forward
0 new messages