Southeast Long-Range Spring 2012 Thread

[Met1985]

Looking at the NAO and the AO and PNA there looks to maybe be a trough in the East the first week in which could cause an outbreak in severe weather. Something to watch going down the road at least.

[Carvers Gap]

If you haven't subscribed to WxSouth.com yet, you should. Robert has a great article about the upcoming pattern in May.

[nchighcountrywx]

If you haven't subscribed to WxSouth.com yet, you should. Robert has a great article about the upcoming pattern in May.

Very informative write up on early summer pattern

Everyone should subscribe to Robert's valuable insight.

[Carvers Gap]

Looking like a cooler/more normal climo pattern is getting ready to hit and hold. The NAO is tanked, the AO as well, and the PNA is going strongly positive. If it were only winter...Anyway, looks like summer may not be a beast like last year. The atmsophere may be finally "recognizing" the Nina is over.

[Marion_NC_WX]

For the last day's worth of runs the GFS has been hinting at early season tropical development around the 20th in the Western Caribbean generally moving towards Western Cuba and eventually between South Florida and the Bahamas...will be interesting to see if this continues over the next couple days.

[LithiaWx]

Looking like a cooler/more normal climo pattern is getting ready to hit and hold. The NAO is tanked, the AO as well, and the PNA is going strongly positive. If it were only winter...Anyway, looks like summer may not be a beast like last year. The atmsophere may be finally "recognizing" the Nina is over.

How about some summertime thunderstorms for a change.

[Carvers Gap]

How about some summertime thunderstorms for a change.

I second that. Been a while since we've seen that "normal" pattern. Last summer was so hot and dry, I've lost all memory of what a normal summer should be...

[Met1985]

Looks like the NAO and the AO will pretty much stay negative for a time. This should help with much need rains and hopefully hold of the heat a little longer.

[buckeyefan1]

I second that. Been a while since we've seen that "normal" pattern. Last summer was so hot and dry, I've lost all memory of what a normal summer should be...

Me too

[metalicwx366]

http://moe.met.fsu.edu/cgi-bin/ecmwf-opertc2.cgi?time=2012051300&field=Sea+Level+Pressure&hour=Animation

[WilkesboroDude]

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

811 AM EDT SUN MAY 13 2012

VALID 12Z THU MAY 17 2012 - 12Z SUN MAY 20 2012

...COASTAL LOW/NOR'EASTER POSSIBLE NEAR THE CAROLINAS NEXT

WEEKEND...

OUTSIDE THE 00Z CANADIAN GUIDANCE BEYOND FRIDAY MORNING...THE

AVAILABLE DETERMINISTIC AND ENSEMBLE MEAN GUIDANCE IS IN VERY GOOD

AGREEMENT CONCERNING THE EXPECTED FLOW PATTERN. TROUGHING BECOMES

ESTABLISHED ACROSS THE INTERMOUNTAIN WEST WHILE RIDGING EXISTS

ACROSS THE PLAINS/MIDWEST AND A DEEP CYCLONE MOVES OFFSHORE THE

SOUTHEAST COAST. SINCE THERE WAS SUCH GOOD AGREEMENT...USED A

40/30/30 BLEND OF THE 00Z UKMET/00Z GFS/00Z ECMWF THROUGH FRIDAY

BEFORE SWITCHING TO A 50/50 BLEND/COMPROMISE OF THE 00Z GFS AND

00Z ECMWF SOLUTIONS. THIS PREFERENCE LED TO GOOD CONTINUITY.

THE DEEP CYCLONE/NOR'EASTER FORECAST OFFSHORE THE SOUTHEAST COAST

THIS WEEKEND HAS A CHANCE TO BECOME A HYBRID SYSTEM AS IT HOVERS

NEAR THE WARM GULF STREAM WATERS FROM FRIDAY INTO EARLY THE

FOLLOWING WEEK. EVEN IF IT REMAINS COLD CORE...THE SYSTEM SHOULD

LEAD TO LOWERED PRESSURES/DISTURBED WEATHER ACROSS THE WESTERN

CARIBBEAN LATE IN THE PERIOD NEAR THE BASE OF ITS UPPER

TROUGH/COLD FRONT...NORMALLY A PROBLEM WHEN A DEEP LAYERED CYCLONE

FORMS BETWEEN THE SOUTHEAST AND BERMUDA. HEAVY COMMA HEAD

RAINS/WINDY CONDITIONS ARE POSSIBLE NEAR THE

CAROLINA/GEORGIA/NORTHEAST FLORIDA COAST IF THE SYSTEM TAKES A

MORE COASTAL ROUTE AS SEEN IN THE 00Z ECMWF. IF IT DEVELOPS AND

STAYS FARTHER OFFSHORE...IT COULD EVOLVE INTO A WILDFIRE CONCERN

FOR SOUTH CAROLINA/GEORGIA/NORTHERN FLORIDA WHICH ARE WITHIN THEIR

ANNUAL SPRING DROUGHT...SIMILAR TO THE SITUATION SEEN DURING

SUBTROPICAL STORM ANDREAS DEVELOPMENT DURING EARLY MAY 2007. THE

POTENTIAL DEVELOPMENT AS SEEN BY ECMWF OVER THE PAST SEVERAL RUNS

IS DIFFERENT THAN THAT OF 2007 EVOLUTION OF ANDREAS...BUT THE

FINAL DEVELOPMENT OF ANDREAS INTO ITS SUBTROPICAL FORM IS SIMILAR

IN THE MID LEVEL H500 FLOW OF THIS EVENT.

VELOCITY POTENTIAL ANOMALIES OF GFS/ECMWF/CMC CONTINUE TO INDICATE

A FAVORABLE ENVIRONMENT FOR TROPICAL DEVELOPMENT IN THE EASTERN

PACIFIC/WESTERN CARRIBEAN AND OFF THE U.S. SOUTHEASTERN SEABOARD.

THE EASTERN PACIFIC ALREADY HAS A SYSTEM READY TO GO AND WILL

LIKELY BE AT LEAST A TROPICAL DEPRESSION IN THE NEXT DAY OR SO.

SEE NHC DISCUSSIONS. THE ATLANTIC SIDE OFF THE SOUTHEASTERN

SEABOARD ALSO HAS FAVROABLE CONDITIONS AS MENTIONED ABOVE WITH A

LARGE NUMBER OF ECMWF ENSEMBLE MEMBERS SUPPORTING THE OPERATIONAL

RUN WITH THE SYSTEM LATE NEXT WEEK AND WEEKEND. BEYOND THIS TIME

FRAME LONGER TERM RUNS OF GFS HAVE BEEN PRODUCING TROPICAL SYSTEMS

IN THE WESTERN CARRIBEAN WITH AN EXIT NORTH AND NORTHEASTWARD.

THIS IS ANOTHER INDICATION THAT THE MODELS RECOGNIZE FUTURE

FAVORABLE DEVELOPMENT CONDITIONS OR CYCLOGENESIS.

UPDATED MORNING PRELIMS REMAIN SIMILAR TO THE OVERNIGHT PACKAGE

WITH AN ADJUSTMENT OF THE SOUTHEASTERN SEABOARD LOW SOUTHWARD OF

THE EARLY PRELIMS OFF THE SC COAST AS A BETTER FIT TO LAGGED

AVERAGE FORECASTS OF ECMWF AND GFS.

ROTH/ROSENSTEIN

[Marion_NC_WX]

This afternoon's GFS hints at Yucatan development Day 7-8 and a possible Florida threat. I'm sure there's plenty of people in lower Georgia and Costal Carolinas would like to see some rainfall.

[Carvers Gap]

Considering that it is almost summer, this really comes as no surprise. The Euro is hinting at a pretty big heat wave during the coming days and most probably weeks. Hopefully it will be in moderation compared to last summer.

[Met1985]

Considering that it is almost summer, this really comes as no surprise. The Euro is hinting at a pretty big heat wave during the coming days and most probably weeks. Hopefully it will be in moderation compared to last summer.

Ya no suprise really. We have been enjoying some great weather as of late. Seems we might be due some sort of heat wave in the near future. Like you said hopefully this in moderation compared to last summer.

[POWERSTROKE]

Very informative write up on early summer pattern

Everyone should subscribe to Robert's valuable insight.

he has been dead on this year. I like his site. he continues to add to it. I talked to him the other day an he said he hopes to have it the way he wants it by winter

[Marion_NC_WX]

The southeast better get ready because the heat is coming late next week...the usual suspects away from the Southern Appalachians will be getting that Heat Index near or above 100 degrees.

[metalicwx366]

Yep 94 by Thursday.

[griteater]

Latest ENSO forecast from dynamical and statistical models...

[mackerel_sky]

So this chart is good,if we want a better,colder snowier winter?

[GaWx]

So this chart is good,if we want a better,colder snowier winter?

IF the average of the dynamic models were to come close to verifying, we'd have a weak El Nino, which would give about the best chances for a good SE US winter. If we could get that along with a -NAO, -AO, and +PDO, our prospects would be about as good as can be.

Here is why I say this (based on Atlanta winters):

2/23/12: 11 Coldest (back to 1879-80) KATL Winters’ ENSO/PDO/NAO/AO

Winter……DJF Temp Anom…ENSO……..PDO*………NAO**….…AO***

1) 1976-7……….…..-7.6…………WEN…....+1.5………..-1.7………..-1.8

2) 1977-8…………...-6.2…………WEN…….+0.7……….-1.1………..-0.5

3) 1904-5……………-5.8………...WEN…….+1.3……….+0.8……….+0.8

4) 1962-3……………-5.8…………WLN……..+0.0……….-1.6………..-0.7

5) 1935-6……………-5.7………….NP………+1.5………-2.0………..-2.4

6) 1963-4……………-5.7…………WEN…….+0.4………-1.6………..-0.7

7) 1939-40………….-5.5…………WEN……..+1.7……...-1.9………..-1.9

8) 1901-2…………...-5.4………….NN………+1.5………-0.7………..-0.5

9) 2009-10………….-4.4…………SEN……..+0.1……..-2.9…………-2.6

10) 1885-6………….-4.3…………WEN……..+0.8……..-0.6…………N/A

11) 1969-70…….…..-4.1………….WEN……..+1.2…….-1.1…………-1.8

Findings:

A very impressive 7 of the 11 coldest (of the 133 winters) and 3 of the 4 coldest were weak Nino’s. Only about 1 in 8 winters is a weak Nino. So, only about 1-2 of the 11 coldest would be the “expected value” if there were no bias of weak Nino’s toward either warm or cold.

The PDO was positive for all 11 (1962-3 was barely above zero).

The NAO was -0.6 or more negative for all but one, 1904-5.

The AO was -0.5 or more negative for all but one, 1904-5. (I couldn’t find the AO for 1885-6.)

Based on the above stats, I’m fully aware that one can make the argument that it was the +PDO/-NAO/-AO combo that was a big reason for the cold for all but 1904-5. However, one could make the argument that the weak Nino phase, itself, also had a major influence. I’ll now explain:

I looked at all winters back to 1879-80 and found 26 that had the +PDO/-NAO/-AO combo, including the 9 noted above from the 11 coldest. A total of 6 of those 26 were weak Nino’s. An impressive 5 of those 6 weak Nino’s (83%) were within the 11 coldest. OTOH, 20 of those 26 +PDO/-NAO/-AO winters were NOT weak Nino’s. Only 4 of those 20 that were +PDO/-NAO/-AO and that weren’t weak Nino’s (20%) were within the 11 coldest. Furthermore, 10 of the 26 were moderate to strong Nino’s. Of those 10 mod. to strong Nino’s with +PDO/-NAO/-AO, only one of the 10 (10%) (2009-10) was within the 11 coldest.

So, to summarize regarding +PDO/-NAO/-AO winters since 1879-80:

- A whopping 83% of the weak Nino’s were in the 11 coldest

- Only 10% of the mod. to strong Nino’s were in the 11 coldest

- Only 20% of all winters that weren’t weak Nino’s were in the 11 coldest

- 40% of weak Nino’s and 47% of moderate to strong Nino’s since 1899-1900 were +PDO/-NAO/-AO….i.e., fairly similar %’s. Yet, weak Nino’s were much colder on average than moderate to strong Nino’s as a whole.

- Conclusion:

The weak Nino phase, itself, has a strong cold tendency for Atlanta independent of the cold tendency resulting from +PDO/-NAO/-AO. The moderate to strong Nino phase lacks this independent strong cold tendency.

---------------------------------------------------------------------------------------------------------------------------------------------------------

*PDO is DJF. 2/2010 was estimated based on this site:

http://jisao.washing.../pdo/PDO.latest

**NAO is DJF. I used a different data source for 1885-6

***AO is DJFM for all since that’s all I could find for pre-1950 and wanted all to be from same source

Datasources:

1) ENSO:

1950+ http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears_1971-2000_climo.shtml

Prior to 1950 http://www.cgd.ucar....limind/TNI_N34/

2) DJF PDO:

ftp://ftp.ncdc.noaa.....1854.latest.ts

3) DJF NAO:

All but 1885-6: https://climatedatag.../nao_pc_djf.txt

1885-6:

http://www.cru.uea.a...ata/nao/nao.dat

4) DJFM AO: https://climatedatag...nam_pc_djfm.txt

[dsaur]

Thanks for this! It is comforting knowing you are sitting on the beach, compiling climatological data, sipping lemonaide, and plotting us a stella winter!

Larry, please find a massive shift in the rain patterns over parts of Ga.! T

[GaWx]

Thanks for this! It is comforting knowing you are sitting on the beach, compiling climatological data, sipping lemonaide, and plotting us a stella winter!

Larry, please find a massive shift in the rain patterns over parts of Ga.! T

Tony,

You're welcome! I try my best.

[jburns]

Thanks for this! It is comforting knowing you are sitting on the beach, compiling climatological data, sipping lemonaide, and plotting us a stella winter!

Larry, please find a massive shift in the rain patterns over parts of Ga.! T

I remember the winter I spent with Stella. What a gal.

[dsaur]

I remember the winter I spent with Stella. What a gal.

Vivian Leigh was hot! T

[GaWx]

It appears that the 5/2012 SOI will be ~-1 to 0. Keeping that in mind, here are the May SOI's for previous first year El Nino's back to 1950 along with the respective Nino strengths using the 1971-2000 climo. for ONI based Nino classification that I've used for a number of years (W = weak; M = moderate; S = strong):

1951: -11.5 W

1957: -11.5 S

1963: +2.5 W

1965: -0.4 S

1968: +14.3 W

1972: -24.0 S

1976: +2.5 W

1982: -7.1 S

1986: -5.6 M

1991: -17.9 S

1994: -11.6 M

1997: -19.0 S

2002: -13.8 M

2004: +13.0 W

2006: -7.7 M

2009: -5.0 S

Going from most +SOI to most -SOI for May, here were the following Nino peaks: W, W, W, W, S, S, M, S, M, W, S, M, M, S, S, S

Note that the three most -SOI May's, -24.0, -19.0, and -17.9, all preceded a strong Nino. Also, note that the four +SOI May's all preceded a weak Nino.

5 W avg. preceding May SOI +4.2 (range: +14.3 to -11.5)

4 M avg. preceding May SOI -9.7 (range: -5.6 to -13.8)

7 S avg. preceding May SOI -12.1 (range: -0.4 to -24.0)

So, only one of the 11 moderate to strong Nino's, 1965-6, had a preceding May SOI near the 5/12 SOI.

My point is that there is some predictive power from the May SOI, which is favoring a weak Nino peak over moderate or strong if there will be a Nino.

Keep in mind that when looking back at recorded history, weak Nino's on average have been the coldest ENSO phase for the SE.

For KATL, specifically, regarding the 16 Weak El Nino’s at KATL ending 2004-5: avg. 41.9F or ~2.7 F below normal DJF; avg. 2.8” S/IP per NDJFMA vs. ~2” longterm avg.; major ZR frequency 1 in 4 WEN winters vs. ~1 in 5 overall avg.; 5 major ZR's in 16 WEN winters vs. ~1 every 4.4 winters; 6 sig. ZR events in 16 WEN winters…so, all ZR stats a bit above avg. So, cold temp.'s, above average major S/IP chances at KATL, and slightly above avg. ZR chances at KATL are all characteristic of weak El Nino's.

Big keys to help get a really cold weak El Nino winter in the SE are a +PDO and -NAO for DJF averaged. So, if we can get a weak El Nino, the hope would then be for a +PDO and -NAO for DJF. By the way, the PDO can be solidly negative prior to winter and still turnaround to a +PDO for DJF.

------------------------------------------------------------------------------------

I used the following link's table for ONI based Nino classification:

http://www.cpc.ncep....000_climo.shtml

I used the following link's table for monthly SOI's:

http://www.longpaddo...87-1989Base.txt

[FallsLake]

This is 10 days out but hopefully there is a trough in the east; which would provide us a cool start to June:

Not sure whats up with the below graph, but this would indicate -NAO into June:

[FallsLake]

GFS still showing a possible cool down (relative for this time of year). 12z GFS at 168 hours:

[andyhb]

The 12z GFS at 156 hrs would probably be a severe weather event across the Carolinas, impressive QPF signal from the model and some significant severe weather parameters showing up, H85 jet of 40-60+ kts, mid level flow in excess of 50 kts leading to 0-6 km bulk shear of 40-60 kts (plenty for supercells), significantly backed sfc flow and CAPE in the 1500-2500 J/kg range.

Remember this is 156 hrs out, but it actually looks quite impressive, given this verbatim...keep an eye on this should trends continue.

That said, the Euro is much different and probably wouldn't result in much of anything...

[Met1985]

Ya Andy the end of the week looks like it is ramping up to be pretty active. Maybe severe weather on one side and then a big cool down on the other side. Looks like the Euro is catching on to this low dipping pretty far south now.

[FoothillsNC]

If you haven't subscribed to WxSouth.com yet, you should. Robert has a great article about the upcoming pattern in May.

he has been dead on this year. I like his site. he continues to add to it. I talked to him the other day an he said he hopes to have it the way he wants it by winter

Thanks for the plug guys!

The 12z GFS at 156 hrs would probably be a severe weather event across the Carolinas, impressive QPF signal from the model and some significant severe weather parameters showing up, H85 jet of 40-60+ kts, mid level flow in excess of 50 kts leading to 0-6 km bulk shear of 40-60 kts (plenty for supercells), significantly backed sfc flow and CAPE in the 1500-2500 J/kg range.

Remember this is 156 hrs out, but it actually looks quite impressive, given this verbatim...keep an eye on this should trends continue.

That said, the Euro is much different and probably wouldn't result in much of anything...

And now the Euro joins it nearly identical. Back in late April I went with a very active pattern in most of the Southeast thanks to signs of neg. NAO and probably troughing in the Southeast for May. A couple of times ECMWF went with big ridging over the Southeast in its long range but GFS more accurately showed some signs of high lat blocking, which ended up being correct. We did (are) still having a pretty impressive heat dome now, but its brief. The overall flow is very unusual, and double blocking is showing up pretty quickly. This makes about 3 times recently it worked out, each time there was very notable weather, which surely beats the previous few years when most of the Southeast gets under too much ridging and not enough rain. Look how much rain has fallen in May. I know what central to northeast GA is going through, usually that dryness extends more northeast through Upstate SC to my area, but I think Beryl will help out some in the next few days plus the incoming front Tuesday will help with decent convergence, so parts of central and esp. South GA will rack up on rain totals soon.

Next few days both major globals show double blocking strongly, which will force a good southerly track to a very impressive storm. It looks like it will develop as it travels through the Southeast, very nice system for early Summer, we don't see this often. I can't remember anything like this recently in this time of year for the Southeast.

Hopefully this repetition of high latitude blocking off and on will keep repeating (or show up again) next Winter when we really can use it. I put a full update at my site, in the free section/Public , so if you haven't registered , please do. Occasionally I put in the free section so more can see what I'm doing.