Medium Range Discussion Spring 2012

[andyhb]

That would be an ugly season, to say the least, although with the currently forecasted telecommunications, I can't argue with it either.

[MDstorm]

2012 Atlantic Hurricane Season Thoughts...

Although an El Niño has not developed, I suspect that odds suggest that the development of an El Niño during the summer are probably somewhat more likely than not. ENSO Region 1+2 has been particularly warm in recent weeks and this may suggest that an El Niño is beginning to take hold even as the easterly Trade Winds have recently resumed. The development of an El Niño could suppress mid- and latter-tropical season activity.

In addition, the Tropical North Atlantic (TNA) Index, an index that measures the SSTAs in the region bounded by 5.5°N-23.5°N/15°W to 57.5°W, has been cool this spring. May is likely to see another cool TNA. Hence, the first third to perhaps half of the Atlantic hurricane season could also be fairly quiet. An abnormally early tropical cyclone cannot be ruled out, as some of the analog seasons had a late May or June tropical cyclone.

Although it is a little soon for me to have a great deal of confidence in the summer/fall pattern, odds seem to favor the highest risk for landfall somewhere along the Gulf Coast. Although the remnants of any such landfalling storm might bring rains to the East Coast, odds of a landfall along the East Coast will probably be below normal.

In terms of tropical cyclone activity, my guess for the 2012 Atlantic season is below:

Tropical Storms or Hurricanes: 8

Hurricanes: 3Y

Major Hurricanes: 1

ACE: 55-65

U.S. Tropical Cyclone Landfalls: 2

U.S. Major Hurricane Landfalls: 0

Leading analogs: 1965 and 2009

That would add to the stinker weather year along the east coast. I would never bet against you, given your track record. Feel free to continue that 2009 analog into the fall and winter season

MDstorm

[am19psu]

Don, I'm going to move that post to the Atlantic Thread, where it is more appropriate.

[donsutherland1]

May 24-31, 2012 Thoughts:

For the week centered around May 9, the ENSO Region 3.4 anomaly had risen to 0.0°C. That is the warmest ENSO Region 3.4 anomaly since the week centered around May 5, 2010. That recent warming despite a return of Easterly trade winds could hint at an El Niño event down the road. It also likely hints at a slower than usual Atlantic hurricane season.

More immediately, it appears May will end on a warmer than normal note across much of North America. The NAEFS are in good agreement with the picture painted by the teleconnection analogs.

The following charts are below:

Top: Teleconnection composite anomalies based on: ENSO Region 3.4 anomalies of -0.2°C to +0.5°C, a PNA of -0.50 to +0.50, and an AO of 0.00 to +1.00 for North America (1950-2011).

Bottom: 5/14/2012 GFS Ensemble 11-15-day 850 mb anomalies.

Taking into consideration the ensemble guidance, NAEFS, decadal trends, and teleconnection composite anomalies, I believe most of North America will experience warmer than normal temperatures for the May 24-31, 2012 timeframe. A portion of California and perhaps the north shore of Alaska could experience cooler than normal readings.

[cbmclean]

May 24-31, 2012 Thoughts:

For the week centered around May 9, the ENSO Region 3.4 anomaly had risen to 0.0°C. That is the warmest ENSO Region 3.4 anomaly since the week centered around May 5, 2010. That recent warming despite a return of Easterly trade winds could hint at an El Niño event down the road. It also likely hints at a slower than usual Atlantic hurricane season.

More immediately, it appears May will end on a warmer than normal note across much of North America. The NAEFS are in good agreement with the picture painted by the teleconnection analogs.

The following charts are below:

Top: Teleconnection composite anomalies based on: ENSO Region 3.4 anomalies of -0.2°C to +0.5°C, a PNA of -0.50 to +0.50, and an AO of 0.00 to +1.00 for North America (1950-2011).

Bottom: 5/14/2012 GFS Ensemble 11-15-day 850 mb anomalies.

Taking into consideration the ensemble guidance, NAEFS, decadal trends, and teleconnection composite anomalies, I believe most of North America will experience warmer than normal temperatures for the May 24-31, 2012 timeframe. A portion of California and perhaps the north shore of Alaska could experience cooler than normal readings.

Don, that is an interesting spatial pattern to the predicted 850 mb anomalies. A large extent of positive anomalies, but the magnitude of the anomalies seems lower than I would expect. Just based on the areal extent, I would expect some yellows oranges and reds to show up in the middle.

[donsutherland1]

Don, that is an interesting spatial pattern to the predicted 850 mb anomalies. A large extent of positive anomalies, but the magnitude of the anomalies seems lower than I would expect. Just based on the areal extent, I would expect some yellows oranges and reds to show up in the middle.

The teleconnection analogs are better at showing areas of warm and cold anomalies than at showing the magnitude of warmth or cold. Getting into greater detail, I suspect that the Midwest could see some much above normal readings especially during the middle and latter portion of the May 24-31 period and some of that heat might spread into the Middle Atlantic and New England states.

[WXheights]

I noticed in the 10 day range of the Midwestern build up of heat making a run toward the Mid-Atlantic, Northeast but it does seem to be underplayed just a bit after the slight cool off mid to late next week also shown by the slight -AO and -NAO but 00Z Euro operational hinting at some warmth getting into the higher latitudes with some sort of zonal break through around the start of June and maybe uptick in severe wx along the Can. border.

Good stuff Don great posts thanks.

[ptb127]

12z GFS goes BONKERS in the east with a massive heat ridge. Looks like first shot at a heat wave coming next weekend. DT on facebook callled for it last night too..

http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller?page=Image&prevPage=Paramℑ=..%2FGemPakTier%2FMagGemPakImages%2Fgfs%2F20120518%2F12%2Fgfs_namer_189_500_rh_ht.gif&fcast=189&imagesurls=&model=GFS&area=NAMER&storm=&areaDesc=North+America+-+US+Canada+and+northern+Mexico&cat=MODEL+GUIDANCE&rname=UPPER+AIR+PARMS&pname=500_rh_ht&cycle=05%2F18%2F2012+12UTC&imageSize=M&currKey=model&scrollx=0&scrolly=0&nextImage=yes

[donsutherland1]

12z GFS goes BONKERS in the east with a massive heat ridge. Looks like first shot at a heat wave coming next weekend. DT on facebook callled for it last night too..

http://mag.ncep.noaa...0&nextImage=yes

Should the much above normal readings prevail, it would be consistent with the majority of my top analogs for May, as noted in Message #204. My top analogs were 1965, 2001, 2002, and 2009. Three of those four cases saw the greatest warmth relative to normal occur after May 20.

[WxLover]

Should the much above normal readings prevail, it would be consistent with the majority of my top analogs for May, as noted in Message #204. My top analogs were 1965, 2001, 2002, and 2009. Three of those four cases saw the greatest warmth relative to normal occur after May 20.

And three of those following Winters had a major snowstorm along the East coast. 66,03,10

[donsutherland1]

And three of those following Winters had a major snowstorm along the East coast. 66,03,10

Hopefully, with the exception of 2001, those analogs will remain relevant into and through the winter.

[WxLover]

Hopefully, with the exception of 2001, those analogs will remain relevant into and through the winter.

I hope your right. Keep up these informative posts, I enjoy reading them.

[donsutherland1]

From Message #204:

...among my top analogs for May (1965, 2001, 2002, and 2009), 3/4 of those cases saw the greatest warmth relative to normal occur after May 20.

Highest readings:

Prior to May 20:

Boston: 80°, May 12 and May 13

New York City: 81°, May 13

Washington, DC: 84°, May 4 and May 19

After May 20:

Boston: 86°, May 26

New York City: 89°, May 28

Washington, DC: 90°, May 28

Greatest Warm Anomaly:

Prior to May 20:

Boston: +13°, May 4

New York City: +10°, May 13

Washington, DC: +13°, May 13

After May 20:

Boston: +15°, May 26

New York City: +14°, May 28

Washington, DC: +10°, May 25, 26, 27, and 28

[donsutherland1]

Verification:

My May 1-7, 2012 thoughts (#153) were as follows:

With the AO likely to be negative leading up to May and the PNA likely to be positive into much or perhaps all of the first week in May, one would typically expect to see cold anomalies in a large part of eastern North America. However, 2012 has not been an ordinary year so to speak. Warmth has consistently outdueled the cold. Even typically cool patterns have underperformed.

If one looks northward, one finds an expansive area of cool anomalies currently located over Canada. However, farther north in the Arctic, warmth predominates. As a result, the cold will likely modify in advance of May and even areas that would typically experience cool weather could wind up on the mild side of normal.

The charts below are as follows:

Top Left: ENSO Region 3.4 anomalies of -0.7°C to 0.0°C, a PNA of -0.25 to +0.50, and an AO of +0.25 to +1.50 for North America (1950-2011).

Top Right: 4/21/2012 12z GFS Ensembles 11-15-day forecast (May 2-6, 2012)

Bottom Left: Northern Hemisphere temperature anomalies for April 18, 2012

Bottom Right: Observed decadal change in temperatures for May

The close of March into the first 12 days of April saw a dramatic burst of westerly winds in the Pacific. In response, there was a fairly dramatic warming of the ENSO regions, with the 2011-12 La Niña coming to an end. However, the past 9 days have been characterized by a rebound in the easterly trade winds. As a result, some cooling of the ENSO regions has taken place and is likely to continue. Right now, it is too soon to know for sure whether an El Niño or Neutral ENSO conditions will be the rule for the summer and beyond. Interestingly enough, among the analogs showing up for the first week in May is 2001.

More immediately, the issue concerns the weather for the first week in May. Taking into consideration the warmth in the Arctic, GFS ensembles, CFSv2 forecast, and the observed decadal temperature change, I expect:

- An area of cool anomalies across Central, Western, and perhaps northern Canada

- Near normal readings in the Southeast

-Near normal to somewhat above normal readings across much of the rest of the U.S.

-Above to perhaps much above normal readings in the Southwest (areas currently experiencing excessive heat)[/i]

The May 1-7, 2012 anomalies were:

[donsutherland1]

Verification:

My May 8-15, 2012 thoughs (#189) were as follows:

...The teleconnection composite anomalies below is based on:

ENSO Region 3.4 anomalies of -0.5°C to +0.1°C, a PNA of 0.00 to +0.75, and an AO of -2.00 to -1.00 for North America (1950-2011).

The latest NAEFS for the May 6-12 timeframe has much of the Northeast, Ohio Valley, and Great Lakes region normal, with cool anomalies focused on the Great Lakes region.

At this time, taking into consideration the ensemble guidance, NAEFS, decadal trends, and teleconnection composite anomalies, I believe the East Coast will likely see readings near or somewhat above normal. An area covering the Central Plains, Northern Plains, Great Lakes area will likely see below normal to near normal readings. The Western third of the U.S. should see above normal readings, with the Desert Southwest and Rockies perhaps seeing the warmest anomalies. Much of Canada should be near normal. However, Central Canada could have below normal readings. Northern Canada could see above to much above normal readings develop.

The May 8-15, 2012 anomalies were as follows:

[donsutherland1]

Verification:

My May 16-23, 2012 thoughts (#208) were as follows:

Another week without excessive early-season heat appears to be on tap in eastern North America.

The teleconnection composite anomalies below is based on:

ENSO Region 3.4 anomalies of -0.3°C to +0.4°C, a PNA of 0.00 to +1.00, and an AO of -0.50 to +0.50 for North America (1950-2011).

The latest NAEFS are reasonably similar, except that they show mainly near normal readings in the areas shown above as cool, and warmth generally elsewhere.

At this time, I suspect that the eastern third of the United States will wind up generally cooler than normal with some areas having near normal readings. The western two-thirds of the U.S. will likely be warmer than normal and the Southwest could be much warmer than normal, though an area running from California into the Pacific Northwest could see somewhat below normal to near normal readings. Most of Canada will probably wind up warmer than normal.

The May 16-23, 2012 anomalies were as follows:

This outcome relative to what typically has occurred in similar patterns provides perhaps a warning that typically cool pattern in the summer, might well wind up on the warmer side of normal barring a cooling of the Arctic region. Already, June looks to be warm in much of the CONUS and a significant portion of Canada.

[cooling climate]

Teleconection composites are just a very rough guide. In reality a high or low

pressure five hundred miles further north, east, south or west will make a big

difference and it has nowt to do with this forums fixation on global warming

and a warming world that keeps getting churned up. To keep saying Enso is

this and the AO etc,etc is that therefore the weather should be X is bad enough

but to take it a step further and keep saying because of a warming world we will

see blah, blah, blah is just plain wrong in my opinion.

[am19psu]

Teleconection composites are just a very rough guide. In reality a high or low

pressure five hundred miles further north, east, south or west will make a big

difference and it has nowt to do with this forums fixation on global warming

and a warming world that keeps getting churned up. To keep saying Enso is

this and the AO etc,etc is that therefore the weather should be X is bad enough

but to take it a step further and keep saying because of a warming world we will

see blah, blah, blah is just plain wrong in my opinion.

lol

[donsutherland1]

Teleconection composites are just a very rough guide. In reality a high or low

pressure five hundred miles further north, east, south or west will make a big

difference and it has nowt to do with this forums fixation on global warming

and a warming world that keeps getting churned up. To keep saying Enso is

this and the AO etc,etc is that therefore the weather should be X is bad enough

but to take it a step further and keep saying because of a warming world we will

see blah, blah, blah is just plain wrong in my opinion.

Teleconnections give insight into the pattern. They are but one tool for trying to develop a medium-term forecast i.e., they supplement the growing range of guidance that is available. If one knew precisely where systems would set up 10, 15, even 20 days down the road, then one wouldn't need to look for such additional insights. But that isn't the case right now.

At the same time, if one wants to try to be reasonably--and the emphasis is on "reasonably" at such timeframes--accurate, one cannot ignore upstream conditions. The absence of cold air (relative to normal) in the Arctic region during December 2001 played a major role in that month's turning out as it did in North America despite impressive blocking. Now, if one wants to discuss reasons for the Arctic warmth, then one should discuss that matter in the climate change forum.

[Chinook]

I'm not sure if this was posted. It was the warmest March-May on record in the USA, breaking the previous record by 2.0 degrees. This is really crazy.

"The national temperature of 57.1 degrees F during spring was 5.2 degrees F above the long-term average, besting the previous warmest spring of 1910 by 2.0 degrees F."

http://www.ncdc.noaa.gov/sotc/service/national/Divisionaltrank/201203-201205.gif

http://www.ncdc.noaa.gov/sotc/service/national/Divisionalprank/201203-201205.gif

http://www.ncdc.noaa.gov/sotc/national/