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Old 10-05-2016, 10:58 AM
 
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Will the PDO go negative during the winter (thanks to La Nina)?


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Old 11-09-2016, 08:54 AM
 
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Old 11-15-2016, 02:06 PM
 
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Blob taking a beating


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Old 12-12-2017, 08:59 PM
 
Location: Near the Coast SWCT
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That damn Pacific... I thought Novembers PDO would be negative. Site not updated but he's saying its positive.

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Old 10-15-2018, 09:59 AM
 
Location: Lizard Lick, NC
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Default AMO Negative Phase Now

The AMO is transitioning into its negative phase. What does that mean for the east coast? Biggest thing is less hurricanes.


Once the anomalously warm waters off the east coast dissipate the AMO index will become firmly negative instead of marginally.


Quote:
Conclusions
The AMO index is a convenient measure of the decadal and longer timescale variability in the Atlantic. However, it is a simple proxy built on the large-scale Atlantic SST anomalies and should be used with caution when trying to understand physical processes in the Atlantic or overlying atmosphere. In particular, in the recent few years, the AMO index has become negative, associated with the strong cold anomaly in the subpolar North Atlantic. This cold anomaly is strikingly cold, and reaches deep into the oceans (as seen in ocean heat content), but the magnitude of the AMO index does not reflect the stark cooling that occurred in the past few years. Instead, a warm subtropical anomaly has partially compensated for the cool subpolar regions, resulting in a marginally negative AMO. The direct influence of the oceanic SSTs on the atmosphere will likely differ between the recent cool anomaly and that in the 1980s and 90 s, when the Atlantic had a cool anomaly over much of its expanse (Fig. 2). This is because the atmosphere responds differently to a cool SST anomaly than to an enhanced meridional SST gradient, the latter of which can increase atmospheric baroclinicity and storminess22.
While the AMO index is only marginally negative, we use spatial information about the distribution of temperature anomalies (both surface and subsurface) to predict that it will persist. Subpolar OHC variations were driven by anomalous air-sea fluxes14, 15 forcing deep convection across the subpolar gyre16, 36. Subpolar OHC variations are typically driven by such irreversible processes, which contributes to the persistent nature of OHC variations, as captured by a statistical forecast (Fig. 4). We show that subpolar OHC anomalies in particular are correlated with the AMO, suggesting that the negative AMO will persist. Subtropical changes are typically adiabatic, and reverse with a reversal of the wind-driven heave. Our findings suggest that the negative AMO index will persist and, if the subtropical anomaly reverses, will intensify.






https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5593924/
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Old 10-15-2018, 11:37 AM
Status: "Will global warming make indianapolis the new death valley?" (set 15 days ago)
 
Location: 46060, Hardiness zone 5b/6a
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You are sure doing a good job dashing all hopes of the Midwest having even an “Normal” winter when it comes to temperatures, thanks alot
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Old 10-15-2018, 09:03 PM
 
Location: Lizard Lick, NC
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Quote:
Originally Posted by Isleofpalms85 View Post
You are sure doing a good job dashing all hopes of the Midwest having even an “Normal” winter when it comes to temperatures, thanks alot
I didn't even mention temperatures lol. Though cold is favored
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Old 10-16-2018, 05:41 AM
 
Location: Near the Coast SWCT
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Great thread... Love the AMO/PDO talk... Maybe can merge into this one?


Pacific PDO & Atlantic AMO Phases
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Old 10-16-2018, 12:08 PM
 
Location: Lizard Lick, NC
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Thanks mods! Can’t believe it’s been almost one year since we talked about two major indexes! We used to speculate ourselves the long range forecast on here using them every year! Lets get back to it !
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Old 10-16-2018, 01:35 PM
 
Location: Near the Coast SWCT
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Q & A regarding the AMO.


What is the AMO?
The AMO is an ongoing series of long-duration changes in the sea surface temperature of the North Atlantic Ocean, with cool and warm phases that may last for 20-40 years at a time and a difference of about 1°F between extremes. These changes are natural and have been occurring for at least the last 1,000 years.

How much of the Atlantic are we talking about?
Most of the Atlantic between the equator and Greenland changes in unison. Some area of the North Pacific also seem to be affected.

What phase are we in right now?
Since the mid-1990s we have been in a warm phase.

What are the impacts of the AMO?
The AMO has affected air temperatures and rainfall over much of the Northern Hemisphere, in particular, North America and Europe. It is associated with changes in the frequency of North American droughts and is reflected in the frequency of severe Atlantic hurricanes. It alternately obscures and exaggerates the global increase in temperatures due to human-induced global warming.

How important is the AMO when it comes to hurricanes - in other words - is it one of the biggest drivers? Or Just a minor player?
During warm phases of the AMO, the numbers of tropical storms that mature into severe hurricanes is much greater than during cool phases, at least twice as many. Since the AMO switched to its warm phase around 1995, severe hurricanes have become much more frequent and this has led to a crisis in the insurance industry.

If the AMO (in part) affects hurricanes - what drives the AMO?
Models of the ocean and atmosphere that interact with each other indicate that the AMO cycle involves changes in the south-to-north circulation and overturning of water and heat in the Atlantic Ocean. This is the same circulation that we think weakens during ice ages, but in the case of the AMO the changes in circulation are much more subtle than those of the ice ages. The warm Gulf Stream current off the east coast of the United States is part of the Atlantic overturning circulation. When the overturning circulation decreases, the North Atlantic temperatures become cooler.
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