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Hey George look... cant be.. the upper level pattern West of us has say in the pattern in the U.S. No way. Cant be. Lol. Cant believe anyone would think theres no major influence
(Btw, CAPS!)
Quote:
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1139 AM EDT TUE MAY 17 2016
VALID 12Z FRI MAY 20 2016 - 12Z TUE MAY 24 2016
PATTERN OVERVIEW...
THE REX-BLOCK ACROSS WESTERN NORTH AMERICA ALTHOUGH WEAK AND
TRANSIENT IN NATURE WILL REMAIN A LARGE INFLUENCE ON THE WEATHER
ACROSS THE CONUS THROUGH THE MEDIUM RANGE PERIOD...WITH CLOSED
LOWS ALONG THE WEST COAST FRIDAY AND SATURDAY AND ALONG THE EAST
COAST SUNDAY THROUGH TUESDAY PRODUCING EXTENDED PERIODS OF COOL
AND WET WEATHER.
MODEL CHOICES/SPREAD/CONFIDENCE...
THE DEVELOPING LARGE CLOSED LOW ALONG THE WEST COAST EARLY IN THE
PERIOD CONTRIBUTES TO REDUCED MODEL SPREAD AND ABOVE AVERAGE
CONFIDENCE EARLY ON...WHILE FROM THE MS VALLEY EASTWARD BELOW
AVERAGE CONFIDENCE EXISTS AS THE EXISTING LOW ACROSS THE ROCKIES
EJECTS EASTWARD WITH POTENTIAL INTERACTION FROM THE NORTHERN
STREAM AND MESOSCALE UNCERTAINTIES DUE TO CONVECTION BOTH
COMPLICATING THE FORECAST. THERE IS ENOUGH ROOM WITHIN THE
SOLUTION ENVELOP ACROSS THE EAST TO ALLOW RAINFALL CHANCES AND
AMOUNTS TO EXPAND FARTHER NORTH INTO NEW ENGLAND ALTHOUGH HIGHER
PROBABILITIES EXISTS THAT THEY WILL NOT
Hey George look... cant be.. the upper level pattern West of us has say in the pattern in the U.S. No way. Cant be. Lol. Cant believe anyone would think theres no major influence
Yes, I agree of course the upper level air pattern west of us, has a dominant influence. Rex blocks aren't dependent on +PDO or -PDO... Of course the SST's at the equator, and the MJO influence us too through El Nino/La Nina. I'm not arguing against this at all. I'm saying that North Pacific SST's (PDO) oscillations do not influence my region as much as other factors. That study said the AMO is more important to our region then the PDO, while the PDO is more important for the west coast obviously. I'm sure a combination of both ocean oscillations.
Also, PNA/NAO/AO would dominate on shorter time scales.
Yes, I agree of course the upper level air pattern west of us, has a dominant influence. Rex blocks aren't dependent on +PDO or -PDO... Of course the SST's at the equator, and the MJO influence us too through El Nino/La Nina. I'm not arguing against this at all. I'm saying that North Pacific SST's (PDO) oscillations do not influence my region as much as other factors. That study said the AMO is more important to our region then the PDO, while the PDO is more important for the west coast obviously. I'm sure a combination of both ocean oscillations.
Also, PNA/NAO/AO would dominate on shorter time scales.
But the PNA is heavily influenced by the SST in the NE Pacific.
It is important to note that the PNA has been found to be strongly influenced by the El Niño-Southern Oscillation (ENSO) phenomenon. The positive phase of the PNA pattern tends to be associated with Pacific warm episodes (El Niño), and the negative phase tends to be associated with Pacific cold episodes (La Niña).
Climate scientist Judith Curry discusses the impact of the AMO on the Southeastern US
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Consider the southeast U.S. (my home territory), which is one of the globe’s cool spots (i.e. it has not been warming). Nevertheless, regional planners find it important to account for the impacts of climate change in their plans out to 2050. Something like 5+ years ago, I was invited by the Atlanta Regional Commission to give a presentation on the latest climate model simulations; they felt they couldn’t act on regional water policy until the climate model results were clarified (the AR4 simulations were all over the place for the southeast U.S.). Because of the dominance of the AMO in this region, planners would be much better off accounting for the multidecadal variability of the AMO rather than AGW
Interesting, with the analogs used, a negative AMO looked to cool the eastern US, however this study is saying that a positive AMO causes cold winters in the US and Europe?
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When the AMO is in its positive phase and the sea surface temperatures are warmer, the study has shown that the main effect in winter is to promote the negative phase of the NAO which leads to "blocking" episodes over the North Atlantic sector, allowing cold weather systems to exist over the eastern US and Europe.
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As the AMO has been in a positive phase since the early 1990s, it may have contributed to the extreme winters that both the US and Europe have experienced in recent years.
The researchers warn, however, that the future evolution of the AMO remains uncertain, with many factors potentially affecting how it interacts with atmospheric circulation patterns, such as Arctic sea ice loss, changes in solar radiation, volcanic eruptions and concentrations of greenhouse gases in the atmosphere.
The AMO also shows strong variability from one year to the next in addition to the changes seen every 60 - 70 years, which makes it difficult to attribute specific extreme winters to the AMO's effects.
Climate scientist Judith Curry discusses the impact of the AMO on the Southeastern US
Regarding this statement. Absolute Ludacris to not mention the Pacific.
"When the AMO is in its positive phase and the sea surface temperatures are warmer, the study has shown that the main effect in winter is to promote the negative phase of the NAO which leads to "blocking" episodes over the North Atlantic sector, allowing cold weather systems to exist over the eastern US and Europe."
What do you think happens when the PNA is negative and a trough is in the Western U.S? No cold air is coming into Eastern U.S no matter if there is blocking in the north Atlantic. Eastern U.S would either be zonal, progressive, or have a ridge. (warm/seasonable)
It starts in the west, Of course the Atlantic matters. EVERYTHING on the map does. If just using PDO and AMO I would say Pacific 60% important, and the Atlantic 40%
Regarding this statement. Absolute Ludacris to not mention the Pacific.
"When the AMO is in its positive phase and the sea surface temperatures are warmer, the study has shown that the main effect in winter is to promote the negative phase of the NAO which leads to "blocking" episodes over the North Atlantic sector, allowing cold weather systems to exist over the eastern US and Europe."
What do you think happens when the PNA is negative and a trough is in the Western U.S? No cold air is coming into Eastern U.S no matter if there is blocking in the north Atlantic. Eastern U.S would either be zonal, progressive, or have a ridge. (warm/seasonable)
Agreed, but does the PNA depend on either -PDO/+PDO? I don't know if it does. Apparently a +AMO promotes more -NAO's and high lat blocking so that for sure would impact the eastern US at least during the winter.
Quote:
It starts in the west, Of course the Atlantic matters. EVERYTHING on the map does. If just using PDO and AMO I would say Pacific 60% important, and the Atlantic 40%
I think it's the opposite. Atlantic 60% and the Pacific 40% over CONUS. Anything west of say the Rockies or at the very least the Great Plains will be more influenced by the AMO phase than the PDO
Look at the 500mb heights in box "E". A warm PDO with a La Nina? Cold winter for eastern US? Am I reading that correctly?
This study is showing that the PDO in either phase does not have a major impact on my region's temps (bv looking at the graphic) but maybe in precipitation.
Agreed, but does the PNA depend on either -PDO/+PDO? I don't know if it does.
PDO is more a lagging effect and an "overall/Average" of the pattern.
PNA is more influenced by other factors. I was simply pointing out that when the PNA is negative, it doesn't matter if there is blocking in the Atlantic, Eastern U.S wont be cold
Quote:
Originally Posted by chicagogeorge
Apparently a +AMO promotes more -NAO's and high lat blocking so that for sure would impact the eastern US at least during the winter.
Yes, it does and so do Tropical systems moving north of Latitude 40N
Quote:
Originally Posted by chicagogeorge
I think it's the opposite. Atlantic 60% and the Pacific 40% over CONUS. Anything west of say the Rockies or at the very least the Great Plains will be more influenced by the AMO phase than the PDO
I wont be the one to convince you but you'll find out one day. Like I said.. play the 500mb loops every single day and watch it. Watch the influence the Pacific has on the pattern in entire U.S. I'm kinda surprised you said that because you know your stuff. But I noticed you don't post discussions from NWS or WPC and probably why you haven't seen more talk of it?
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1139 AM EDT SAT MAY 21 2016
VALID 12Z TUE MAY 24 2016 - 12Z SAT MAY 28 2016...
A SIGNIFICANT CHANGE TO THE OVERALL PATTERN WILL SEE THE EASTERN TROUGH FINALLY LIFTING NORTHEASTWARD AS RIDGING BRINGS WARMER TEMPERATURES TO MUCH OF THE EASTERN STATES BY WEDNESDAY.
SEVERAL UPPER TROUGHS WILL DOMINATE THE FLOW ACROSS THE WESTERN UNITED STATES STATES THROUGH THE PERIOD.
Heat Ridge in East all because of the Jet digging in the West. Very little to do with the Atlantic. More to do with the current Typhoon than the AMO
I wont be the one to convince you but you'll find out one day. Like I said.. play the 500mb loops every single day and watch it. Watch the influence the Pacific has on the pattern in entire U.S. I'm kinda surprised you said that because you know your stuff. But I noticed you don't post discussions from NWS or WPC and probably why you haven't seen
I'm just regurgitating what I've been reading in the studies done on the AMO/PDO. The more research I do, the more I'm convinced that the AMO is a bigger driver than the PDO for the eastern US. Of course they work together to produce varying effects on climate.
I haven't seen a study more detailed than this on how the AMO/PDO effect the different regions of the US.
Quote:
Atmospheric temperature time series for the nine climate regions of the contiguous U.S. are accurately reproduced by the superposition of oscillatory modes, representing the Atlantic multidecadal oscillation (AMO) and the Pacific decadal oscillation (PDO), on a monotonic mode representing, at least in part, the effect of radiant forcing due to increasing atmospheric CO2. The relative importance of the different modes varies among the nine climate regions, grouping them into three mega-regions: Southeastern comprising the South, Southeast and Ohio Valley; Central comprising the Southwest, Upper Midwest, and Northeast; and Northwestern comprising the West, Northwest, and Northern Rockies & Plains. The defining characteristics of the mega-regions are: Southeastern – dominated by the AMO, no PDO influence; Central – influenced by the AMO, no PDO influence, Northwestern – influenced by both the AMO and PDO. Temperature vs. time curves calculated by combining the separate monotonic and oscillatory modes agree well with the measured temperature time series, indicating that the 1938-1974 small decrease in contiguous U.S. temperature was caused by the superposition of the downward-trending oscillatory mode on the upward-trending monotonic mode while the 1980-2000 large increase in temperature was caused by the superposition of the upward-trending oscillatory mode on the upward-trending monotonic mode. The oscillatory mode, mostly representing the AMO, was responsible for about 72% of the entire contiguous U.S. temperature increase over that time span with the contribution varying from 86 to 42% for individual climate regions.
Also think "Younger Dryas". When the Atlantic cooled as a result of the AMOC shutting down 12000 years ago, North America and especially Europe plunged into near ice age conditions for over 1000 years.
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Europe
As the Northern Hemisphere was recovering from the last ice age about 15,000 years ago, the climate warmed dramatically and trees started to colonize the landscape. Evidence of the warming was first found in Scandinavia by geologists who noticed tree fossils in organic sediment. They named the warming interval the Allerød for the locale where it was first observed. Overlying the Allerød layer were leaves and fruits of Dryas octopetala, an arctic-alpine herb, in sandy or silty (minerogenic) layers above the peaty tree remains; this suggested that the climate had reverted several times to very cold conditions. Two such reversals to frigid conditions were named the Older and Younger Dryas (Jansen, 1938). Considerable evidence of this sequence in hundreds of pollen diagrams throughout Europe (Iversen, l954; Watts, l980) brought attention to the strongest effects of the event, which occurred in coastal Europe. During the Younger Dryas, pollen of tundra plants, such as Artemisia (wormwood) and Chenopodiaceae, abruptly replaced birch and even conifer pollen (e.g., Lowe et al., 1995; Walker, 1995; Renssen and Isarin, 1998; Birks and Ammann, 2000). In Norway, mean July temperature was about 7-9°C lower than today and about 2-4°C lower than the preceding warm Allerød interval (Birks and Ammann, 2000). It is now apparent that regional climate changes were also large in southern Europe (Lowe and Watson, l993; Beaulieu et
Quote:
North America
For many years, the Younger Dryas was thought to be a solely European event (Mercer, l969; Davis et al., 1983). It was the high-resolution reexamination of pollen stratigraphy, the identification of plant macrofossils, and the new technique of accelerator mass spectrometry 14C dating of these macrofossils that enabled documentation of the event in the southern New England region of the United States (Peteet et al., l990, 1993) and in the eastern maritime provinces of Canada (Mott, 1994; Mayle et al., l993). The climate signal in southern New England was a 3-4°C July cooling; in eastern Canada, a cooling of 6-7°C is estimated (from pollen). Midge fly fossils in lake sediments from the White Mountains of New Hampshire indicate about 5°C Younger Dryas cooling of maximum summertime lake temperatures, a somewhat smaller change than suggested for a coastal transect from Maine to New Brunswick (Cwynar and Spear, 2001). In the central Appalachians, a warm, wet interval coincident with the Younger Dryas event suggests a sharp climatic gradient that might have forced the northward movement of storm-track moisture (Kneller and Peteet, l999). Later North American studies have identified the Younger Dryas event in other regions, such as the US Midwest (Shane and Anderson, l993), coastal British Columbia (Mathewes, l993) and coastal Alaska (Peteet and Mann, l994). The documentation of the Younger Dryas event over much of North America demonstrated that it was not limited to the circum-Atlantic region (Peteet et al., l997).
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