WEATHERAmerica Newsletter, Saturday, July 25, 2015 (Longer Term Forecast)
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Larry Cosgrove
Jul 25, 2015, 10:12:01 PM7/25/15
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EXTENDED PERIOD FORECAST
(Between Day 11 And Day 15)
High Latitude Blocking Signals, Eastern U.S. Trough And Weakness Provide Period Of Cooler, Stormy Conditions Over Eastern North America
NRL
EUMETSAT
NOAA/NCEP
NOAA/TAO
EUMETSAT
NOAA/NCEP
NOAA/TAO
NOAA/CPC (2)
HPRCC/University Of Nebraska (2)
Environment Canada
Environment Canada
TropicalTidbits.Com (Levi Cowan) (5)
Despite the confusion amid the veritable ton of hyped and unsubstantiated media reports concerning the ongoing El Nino episode, some parts of the longer term forecast appear to be a fairly easy read. For instance, we know that the northern jet stream storm sequence is likely to continue well into August. Bolstered by the vigorous monsoonal flow from the Indian Ocean, which takes an eastern route over parts of the PRC and Japan, the series of impulses will ride over a ridge signature across the western half of the continent. That tendency for ridging in the -AO and +PNA positions may itself be aided by the very warm sea surface temperatures over the eastern third of the Pacific Ocean, which appear to be holding firm from the Gulf of Alaska to south and west of Baja California.
Now the main forecast question is this: will shortwaves which weaken going through the higher latitude ridge signals rebound and dig into the eastern half of North America. The European ensemble group says yes, but the American and Canadian series supply a more muted trough axis from Ontario and Quebec into the eastern Gulf of Mexico. If you blend the three packages, the result still yield s a hot. drier West and cool, sometimes stormy East as we go through the middle of August. The CFS series has been a disaster with its temperature predictions (always far colder than the verified result), but to its credit the 500MB outlook has been spot on.
The tropical cyclone threat will be in the slight-to-marginal realm for the western Atlantic Basin, since the best cases for Caribbean Sea development would likely be steered into Mexico or Central America. All of the computer models are very bullish on a prominent hurricane along or near the Mexican Pacific shoreline in the 11 - 15 day time fame. But systems of the Cape Verde variety (off of Eastern Africa) will have to deal with abundant Saharan heat and dust, so the minimal risk to the U.S. would have to be from the Gulf of Mexico system, Caribbean or Sargasso Seas.
Despite the confusion amid the veritable ton of hyped and unsubstantiated media reports concerning the ongoing El Nino episode, some parts of the longer term forecast appear to be a fairly easy read. For instance, we know that the northern jet stream storm sequence is likely to continue well into August. Bolstered by the vigorous monsoonal flow from the Indian Ocean, which takes an eastern route over parts of the PRC and Japan, the series of impulses will ride over a ridge signature across the western half of the continent. That tendency for ridging in the -AO and +PNA positions may itself be aided by the very warm sea surface temperatures over the eastern third of the Pacific Ocean, which appear to be holding firm from the Gulf of Alaska to south and west of Baja California.
Now the main forecast question is this: will shortwaves which weaken going through the higher latitude ridge signals rebound and dig into the eastern half of North America. The European ensemble group says yes, but the American and Canadian series supply a more muted trough axis from Ontario and Quebec into the eastern Gulf of Mexico. If you blend the three packages, the result still yield s a hot. drier West and cool, sometimes stormy East as we go through the middle of August. The CFS series has been a disaster with its temperature predictions (always far colder than the verified result), but to its credit the 500MB outlook has been spot on.
The tropical cyclone threat will be in the slight-to-marginal realm for the western Atlantic Basin, since the best cases for Caribbean Sea development would likely be steered into Mexico or Central America. All of the computer models are very bullish on a prominent hurricane along or near the Mexican Pacific shoreline in the 11 - 15 day time fame. But systems of the Cape Verde variety (off of Eastern Africa) will have to deal with abundant Saharan heat and dust, so the minimal risk to the U.S. would have to be from the Gulf of Mexico system, Caribbean or Sargasso Seas.
Prepared by Meteorologist LARRY COSGROVE on
Saturday, July 25, 2015 at 9:10 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 2015 by Larry Cosgrove
Saturday, July 25, 2015 at 9:10 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 2015 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.
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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