ATL: ERNESTO - Post-Tropical

[gatorcane]

I believe that little swirl racing westward ahead of the convection is what's left of Ernesto's center. Certainly don't see any circulation south of 15N where the models initialized. I'm not so sure Ernesto will recover. Could move into Honduras/Nicaragua tomorrow afternoon/evening and be gone. No north turn into the Gulf.

and that is what the GFS model was calling for days ago for this....and nobody could understand why it wasn't strengthening the system and why it was burying it in Central America. So far the GFS is performing very well this year (Debby is another example that comes to mind). I think the general rule is if the GFS and ECMWF are both in reasonable agreement on both track and intensity, chances are pretty high that is what the outcome is going to be no matter what all of the other models are doing. In fact I would argue that those two models alone can be used for forecasting these systems for both track and intensity.

[tolakram]

[Sanibel]

There is very little shear near Ernesto's LLC right now.

This is a good example of what I call "synoptic shear". If you look at the loop the convection is definitely displaced to the east. The naked spiral tells you shear is pushing the convection off of it. This displacement isn't being caused by wind it's being caused by a different, drier synoptic airmass. Case in point.

[cheezyWXguy]

If the shear has displaced the convection to the east and dry air exists to the west then the shear is coming from the dry air direction and therefore has to be partly responsible.

There is very little shear near Ernesto's LLC right now.

In roughly the same vicinity, Hurricane Gustov went from 45 to 145 in eighteen hours despite 30kts of southwesterly shear in the mid-levels.

Difference? Gustov had a clear pipe to 200mb.

Out in the Atlantic, Florence is dumb-belling around dealing with the nearby SAL (which is way dryer than anything lurking in the Caribbean) and hanging on. It too has no cap problem.

Ernesto has been in close proximity to South America and a large amount of dry air to its west during its entire trip through the carib so far, meaning its inflow channel has more than likely been pulling dry air into the circulation periodically. Its also probably not the only factor, as Ernesto has also been moving unfavorably fast, inhibiting its ability to develop a very tight core and that has probably been responsible for the repeated structural fluctuations as well. You seem to like to try and prove your points by alluding to anomalous events, but thats what they are. Anomolies. Gustav and Joan did not behave in a 'normal' or 'average' fashion and that makes them not very useful in making accurate predictions.

[wjs3]

Yeah, around the spot where the first pressure minimum was (1007) there was a windshift, but around the 1006 spot, no shift.

Looking more and more like a wave!

[Ntxw]

Yep, looks like CA is coming into play now. Not looking good either for Ernesto with his continuing quick pace movement. Remember some calling for RI the next 24 hours yesterday and that has not materialized and gone opposite. Just to show how rare a feat that is to do, especially with no support from the two important models agreeing with each other.

[artist]

000
URNT15 KNHC 051419
AF302 0605A ERNESTO HDOB 31 20120805
141030 1556N 07726W 9067 00952 0111 +196 +170 068029 030 024 001 00
141100 1557N 07728W 9138 00879 0111 +197 +171 068028 030 030 002 00
141130 1558N 07729W 9214 00809 0111 +203 +172 068029 030 030 001 00
141200 1559N 07730W 9293 00737 0112 +208 +174 066031 031 022 000 00
141230 1600N 07731W 9370 00666 0113 +211 +176 066032 033 024 001 00
141300 1602N 07733W 9447 00594 0113 +213 +179 064031 033 024 000 03
141330 1602N 07734W 9507 00537 0110 +218 +183 063030 031 /// /// 03
141400 1601N 07735W 9528 00517 0108 +222 +187 059029 030 023 002 00
141430 1559N 07735W 9569 00481 0108 +225 +191 058027 029 024 000 00
141500 1557N 07736W 9596 00455 0107 +226 +193 055026 027 023 001 00
141530 1556N 07736W 9597 00452 0105 +225 +194 055028 029 019 000 00
141600 1554N 07736W 9594 00455 0105 +230 +195 057028 029 020 000 00
141630 1552N 07736W 9590 00458 0104 +226 +196 054027 028 020 001 00
141700 1551N 07736W 9594 00452 0103 +228 +196 056028 029 020 001 00
141730 1549N 07737W 9593 00455 0102 +226 +197 055026 027 019 001 00
141800 1547N 07737W 9596 00451 0102 +227 +197 055025 027 020 000 00
141830 1546N 07737W 9594 00451 0101 +225 +198 053025 027 019 001 00
141900 1544N 07737W 9594 00449 0099 +225 +198 051027 028 014 001 00
141930 1542N 07737W 9594 00447 0097 +228 +197 053027 028 012 001 03
142000 1540N 07738W 9591 00450 0096 +230 +197 053027 028 017 001 00
$$

[SFLcane]

Another view of ernesto's stripped llc...

[Sanibel]

The unseen factor is 'relative shear' caused by Ernesto's fast forward speed while travelling into a drier airmass.

[Ntxw]

Even the whacky NAM is going in central america. That camp is growing significantly and becoming the growing consensus.

[Portastorm]

Well, OK... May I ask: is it ever possible to disagree with a pro-met (however obliquely and without mentioning any particular name) here?

Answer: Sure it is and Storm2K members do it all the time in a polite and respectful manner. In nearly every case, the reasonings and explanations from our pro mets prove out and the member, an amateur, learns something. And yes our pro mets are humans and sometimes they do err. But I've been around here a long time and I haven't seen that often. Why? Because our pro mets know of what they speak and they carefully evaluate their posts before hitting that "submit" button.

It's one thing to respectfully disagree. It's another to tell a pro met or the NHC or NOAA that they're figuratively on crack and way wrong.

[tolakram]

The unseen factor is 'relative shear' caused by Ernesto's fast forward speed while travelling into a drier airmass.

I was thinking that as well. I'm not 100% certain how shear is measured but I assume from the basis of a still object. With the LLC moving west at 20kts this, in my mind, introduced 20kts of shear.

[jinftl]

We had the model divergence...and let's face it, any model that goes against a system growing intense and heading into the Gulf, will be scoffed at for as long as it is possible on the board. Plus add the fact that as a whole, we do tend to intensify storms before recon or the NHC has confirmed this, so it almost feels like we went from a major hurricane to barely as tropical system...in reality, he never made it past 60 mph officially. All these reasons are why i keep coming back here for each storm - never dull!!!

I believe that little swirl racing westward ahead of the convection is what's left of Ernesto's center. Certainly don't see any circulation south of 15N where the models initialized. I'm not so sure Ernesto will recover. Could move into Honduras/Nicaragua tomorrow afternoon/evening and be gone. No north turn into the Gulf.

and that is what the GFS model was calling for days ago for this....and nobody could understand why it wasn't strengthening the system and why it was burying it in Central America. So far the GFS is performing very well this year (Debby is another example that comes to mind). I think the general rule is if the GFS and ECMWF are both in reasonable agreement on both track and intensity, chances are pretty high that is what the outcome is going to be no matter what all of the other models are doing. In fact I would argue that those two models alone can be used for forecasting these systems for both track and intensity.

[artist]

000
URNT15 KNHC 051429
AF302 0605A ERNESTO HDOB 32 20120805
142030 1539N 07738W 9594 00447 0097 +230 +197 053023 026 019 001 00
142100 1537N 07739W 9594 00447 0095 +228 +198 055024 024 020 002 00
142130 1536N 07740W 9594 00445 0095 +223 +199 057026 026 022 000 03
142200 1534N 07740W 9596 00445 0096 +225 +199 047024 025 024 000 00
142230 1532N 07741W 9594 00446 0096 +225 +199 044024 025 022 002 00
142300 1531N 07741W 9592 00446 0094 +223 +199 044022 025 017 001 00
142330 1529N 07741W 9595 00444 0093 +227 +199 049023 025 019 000 00
142400 1527N 07742W 9594 00442 0091 +234 +198 052027 027 016 001 00
142430 1525N 07742W 9594 00442 0091 +235 +198 051028 029 010 002 00
142500 1524N 07742W 9594 00444 0090 +235 +199 052027 028 014 001 00
142530 1522N 07742W 9596 00440 0089 +235 +199 050026 027 018 000 00
142600 1520N 07742W 9594 00441 0088 +235 +200 047026 027 017 000 03
142630 1519N 07742W 9589 00445 0087 +233 +201 049027 027 008 003 03
142700 1519N 07740W 9597 00436 0086 +232 +203 055027 028 013 001 00
142730 1518N 07739W 9595 00436 0084 +229 +204 055026 028 012 001 00
142800 1518N 07737W 9594 00438 0085 +229 +205 054025 026 014 000 00
142830 1518N 07736W 9594 00439 0086 +229 +205 054023 025 015 000 00
142900 1518N 07735W 9593 00439 0086 +231 +204 052022 023 014 001 00
142930 1518N 07733W 9596 00438 0085 +232 +204 049023 024 011 002 03
143000 1518N 07732W 9594 00439 0086 +230 +203 046023 023 014 001 00
$$
;

[amawea]

I believe that little swirl racing westward ahead of the convection is what's left of Ernesto's center. Certainly don't see any circulation south of 15N where the models initialized. I'm not so sure Ernesto will recover. Could move into Honduras/Nicaragua tomorrow afternoon/evening and be gone. No north turn into the Gulf.

and that is what the GFS model was calling for days ago for this....and nobody could understand why it wasn't strengthening the system and why it was burying it in Central America. So far the GFS is performing very well this year (Debby is another example that comes to mind). I think the general rule is if the GFS and ECMWF are both in reasonable agreement on both track and intensity, chances are pretty high that is what the outcome is going to be no matter what all of the other models are doing. In fact I would argue that those two models alone can be used for forecasting these systems for both track and intensity.

This! You are 100% correct gatorcane. The GFS nailed this, and I believe it is probably the best model from 4 or 5 days out right now.

[Sanibel]

I was thinking that as well. I'm not 100% certain how shear is measured but I assume from the basis of a still object. With the LLC moving west at 20kts this, in my mind, introduced 20kts of shear.

I don't want to go over my head, but shear is simply the measured wind at that level. So even in no shear the forward speed into this Potential Vorticity cap is enough to replicate kinetic shear. That's why it is 'synoptic shear' instead of straight wind shear. So the cap theory is probably at least partly responsible and therefore right. As usual with these disagreements both sides are right, but with cyclones there's so many variables that someone else will always have a counter argument.

[Portastorm]

Well this may raise a few eyebrows around here ...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1000 AM EDT SUN AUG 05 2012

VALID 12Z THU AUG 09 2012 - 12Z SUN AUG 12 2012

...ERNESTO EXPECTED TO MOVE THROUGH THE SOUTHERN AND WESTERN GULF
OF MEXICO THIS PERIOD...

LOCATED IN THE CENTRAL CARIBBEAN...ERNESTO IS STRUGGLING TO
ORGANIZE AS IT MOVES AT A RAPID CLIP TO THE WEST. CONDITIONS ARE
EXPECTED TO BECOME MORE FAVORABLE FOR INTENSIFICATION AS IT SLOWS
DOWN ACROSS THE NORTHWEST CARIBBEAN SEA IN 2-3 DAYS. THE NATIONAL
HURRICANE CENTER HAS ERNESTO WAVERING NEAR MINIMAL HURRICANE
STRENGTH FROM TUESDAY NIGHT THROUGH THURSDAY NIGHT...AND THE
PRESSURE MAPS BEYOND THEN MAINTAIN THAT IDEA UNTIL ITS FINAL
LANDFALL IN NORTHEAST MEXICO FRIDAY NIGHT. CURRENT 00Z GLOBAL
ENSEMBLE GUIDANCE HAD NARROWED SINCE FRIDAY...SHOWING A LANDFALL
ACROSS MEXICO NORTH OF VERA CRUZ STATE. CONFIDENCE IN THIS TRACK
IS NEAR AVERAGE OR ABOVE AVERAGE. IT IS WORTH
NOTING...HOWEVER...THAT A MINORITY OF ENSEMBLE
MEMBERS...PARTICULARLY FROM THE ECMWF ENSEMBLE...STEER ERNESTO
FARTHER NORTH. UNCERTAINTY DOES INCREASE BY EARLY NEXT
WEEKEND...AND A NORTHWARD SHIFT IN THE TRACK IS AT LEAST PLAUSIBLE
IF ERNESTO BECOMES INFLUENCED BY A MID LEVEL HEIGHT
WEAKNESS/TROUGH THAT TAKES SHAPE ALONG THE GULF COAST OF THE U.S.
THEREFORE... PEOPLE WITH INTERESTS ALONG THE GULF
COAST...PARTICULARLY IN SOUTH TEXAS...SHOULD CONTINUE TO MONITOR
THE OFFICIAL FORECASTS FROM THE NATIONAL HURRICANE CENTER.
...NORTH AMERICAN SYNOPSIS...

WITH TIME...THE PERSISTENT TROUGH IN THE EAST PACIFIC IS FORECAST
TO DAMPEN...WITH ZONAL FLOW INCREASING ALONG THE WESTERN HALF OF
THE U.S./CANADIAN BORDER ATOP A STOUT UPPER RIDGE IN THE WEST. A
RELATIVELY VIGOROUS SHORTWAVE TROUGH DROPS SOUTHWARD INTO THE
GREAT LAKES EARLY IN THE MEDIUM RANGE PERIOD...AND THE COMBINES
WITH SHORT WAVES RIDING THE PERIPHERY OF THE RIDGE...TO CARVE OUT
A DEEP TROUGH IN THE EAST...RELATIVE TO THE SEASON. ACROSS THE
NORTHWEST...SYSTEMS MOVING OVER THE TOP OF THE WARM CORE RIDGE
ATTEMPT TO BRING WEAK FRONTAL INCURSIONS INTO THE REGION EVERY 2-3
DAYS...ONLY TO RETURN NORTHWARD INTO THE HIGH PLAINS AS THE RIDGE
REBOUNDS.

...MODEL CHOICE...

THE 00Z GFS AND GEFS MEAN BEST FIT OUR CONCEPTUAL MODEL FOR TIMING
OF THE TROUGH DIGGING IN THE EAST...AND FOR MAINTAINING THE
IDENTITY OF SHORT WAVE TROUGHS TOPPING THE RIDGE AND DROPPING INTO
THE PLAINS ON DY 3/4 AND AGAIN 6/7. THE 00Z ECMWF CONTINUES AS A
SLOW OUTLIER WITH THE EASTERN TROUGH INITIALLY...BUT COMES BETTER
INTO PHASE WITH TIME. THE 00Z CANADIAN WAS ALSO IN LINE WITH THE
GFS.
THE 00Z UKMET WAS THE OUTLIER THIS PERIOD IN MOVING THE TROUGHING
ACROSS THE GREAT LAKES QUICKER TO THE EAST.

BURKE/ROTH

[tailgater]

We had the model divergence...and let's face it, any model that goes against a system growing intense and heading into the Gulf, will be scoffed at for as long as it is possible on the board. Plus add the fact that as a whole, we do tend to intensify storms before recon or the NHC has confirmed this, so it almost feels like we went from a major hurricane to barely as tropical system...in reality, he never made it past 60 mph officially. All these reasons are why i keep coming back here for each storm - never dull!!!

SOOO true.

I learn a little more with each storm like this. Great past time till football season starts. We had the model divergence...and let's face it, any model that goes against a system growing intense and heading into the Gulf, will be scoffed at for as long as it is possible on the board. Plus add the fact that as a whole, we do tend to intensify storms before recon or the NHC has confirmed this, so it almost feels like we went from a major hurricane to barely as tropical system...in reality, he never made it past 60 mph officially. All these reasons are why i keep coming back here for each storm - never dull!!!

SOOO true.

I learn a little more with each storm like this. Great past time till football season starts.

[artist]

URNT15 KNHC 051439
AF302 0605A ERNESTO HDOB 33 20120805
143030 1519N 07730W 9618 00417 0087 +230 +204 042022 023 014 002 00
143100 1519N 07730W 9618 00417 0086 +230 +204 043022 023 015 001 00
143130 1519N 07730W 9618 00417 0086 +230 +204 043022 023 015 001 00
143200 1519N 07730W 9618 00417 0086 +230 +204 043022 023 015 001 00
143230 1519N 07724W 9630 00414 0091 +230 +205 036024 026 015 001 03
143300 1519N 07723W 9628 00415 0094 +230 +205 034026 028 /// /// 03
143330 1519N 07721W 9635 00406 0093 +230 +205 032031 031 /// /// 03
143400 1519N 07720W 9624 00402 0079 +230 +205 030030 032 /// /// 03
143430 1519N 07718W 9630 00396 0074 +228 +205 030030 032 /// /// 03
143500 1519N 07717W 9630 00394 0072 +226 +205 033029 030 /// /// 03
143530 1519N 07715W 9628 00394 0072 +225 +205 030029 030 /// /// 03
143600 1519N 07714W 9634 00390 0073 +225 +205 028032 033 /// /// 03
143630 1519N 07713W 9629 00397 0076 +224 +205 027031 034 /// /// 03
143700 1519N 07711W 9634 00393 0077 +224 +205 029029 029 /// /// 03
143730 1519N 07710W 9630 00397 0076 +225 +204 034027 029 /// /// 03
143800 1519N 07708W 9628 00399 0075 +225 +204 031027 027 /// /// 03
143830 1519N 07707W 9632 00393 0074 +227 +204 031027 027 /// /// 03
143900 1519N 07705W 9630 00391 0071 +228 +205 029026 027 /// /// 03
143930 1519N 07704W 9630 00390 0068 +230 +205 030024 026 /// /// 03
144000 1519N 07702W 9630 00389 0067 +230 +205 034021 023 /// /// 03
$$
;

[jinftl]

11am Discussion pretty much lowers that eyebrow:

ALTHOUGH THE
GFDL AND U.K. MET MODEL FORECASTS SHOW A MOTION TOWARD THE
NORTHWEST GULF COAST IN THE LATTER PART OF THE FORECAST
PERIOD...THE TROUGH IS NOT EXPECTED TO WEAKEN THE RIDGE ENOUGH TO
CAUSE A SIGNIFICANT NORTHWARD TURN. THIS IS CONFIRMED BY THE GFS
AND ECMWF RUNS...AND IN FACT THE LATEST GFS FORECAST BARELY BRINGS
THE TROPICAL CYCLONE INTO THE GULF. THE OFFICIAL FORECAST IS A
LITTLE SOUTH OF THE PREVIOUS ONE...AND CLOSE TO THE ECMWF TRACK.

Well this may raise a few eyebrows around here ...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1000 AM EDT SUN AUG 05 2012

VALID 12Z THU AUG 09 2012 - 12Z SUN AUG 12 2012

...ERNESTO EXPECTED TO MOVE THROUGH THE SOUTHERN AND WESTERN GULF
OF MEXICO THIS PERIOD...

LOCATED IN THE CENTRAL CARIBBEAN...ERNESTO IS STRUGGLING TO
ORGANIZE AS IT MOVES AT A RAPID CLIP TO THE WEST. CONDITIONS ARE
EXPECTED TO BECOME MORE FAVORABLE FOR INTENSIFICATION AS IT SLOWS
DOWN ACROSS THE NORTHWEST CARIBBEAN SEA IN 2-3 DAYS. THE NATIONAL
HURRICANE CENTER HAS ERNESTO WAVERING NEAR MINIMAL HURRICANE
STRENGTH FROM TUESDAY NIGHT THROUGH THURSDAY NIGHT...AND THE
PRESSURE MAPS BEYOND THEN MAINTAIN THAT IDEA UNTIL ITS FINAL
LANDFALL IN NORTHEAST MEXICO FRIDAY NIGHT. CURRENT 00Z GLOBAL
ENSEMBLE GUIDANCE HAD NARROWED SINCE FRIDAY...SHOWING A LANDFALL
ACROSS MEXICO NORTH OF VERA CRUZ STATE. CONFIDENCE IN THIS TRACK
IS NEAR AVERAGE OR ABOVE AVERAGE. IT IS WORTH
NOTING...HOWEVER...THAT A MINORITY OF ENSEMBLE
MEMBERS...PARTICULARLY FROM THE ECMWF ENSEMBLE...STEER ERNESTO
FARTHER NORTH. UNCERTAINTY DOES INCREASE BY EARLY NEXT
WEEKEND...AND A NORTHWARD SHIFT IN THE TRACK IS AT LEAST PLAUSIBLE
IF ERNESTO BECOMES INFLUENCED BY A MID LEVEL HEIGHT
WEAKNESS/TROUGH THAT TAKES SHAPE ALONG THE GULF COAST OF THE U.S.
THEREFORE... PEOPLE WITH INTERESTS ALONG THE GULF
COAST...PARTICULARLY IN SOUTH TEXAS...SHOULD CONTINUE TO MONITOR
THE OFFICIAL FORECASTS FROM THE NATIONAL HURRICANE CENTER.
...NORTH AMERICAN SYNOPSIS...

WITH TIME...THE PERSISTENT TROUGH IN THE EAST PACIFIC IS FORECAST
TO DAMPEN...WITH ZONAL FLOW INCREASING ALONG THE WESTERN HALF OF
THE U.S./CANADIAN BORDER ATOP A STOUT UPPER RIDGE IN THE WEST. A
RELATIVELY VIGOROUS SHORTWAVE TROUGH DROPS SOUTHWARD INTO THE
GREAT LAKES EARLY IN THE MEDIUM RANGE PERIOD...AND THE COMBINES
WITH SHORT WAVES RIDING THE PERIPHERY OF THE RIDGE...TO CARVE OUT
A DEEP TROUGH IN THE EAST...RELATIVE TO THE SEASON. ACROSS THE
NORTHWEST...SYSTEMS MOVING OVER THE TOP OF THE WARM CORE RIDGE
ATTEMPT TO BRING WEAK FRONTAL INCURSIONS INTO THE REGION EVERY 2-3
DAYS...ONLY TO RETURN NORTHWARD INTO THE HIGH PLAINS AS THE RIDGE
REBOUNDS.

...MODEL CHOICE...

THE 00Z GFS AND GEFS MEAN BEST FIT OUR CONCEPTUAL MODEL FOR TIMING
OF THE TROUGH DIGGING IN THE EAST...AND FOR MAINTAINING THE
IDENTITY OF SHORT WAVE TROUGHS TOPPING THE RIDGE AND DROPPING INTO
THE PLAINS ON DY 3/4 AND AGAIN 6/7. THE 00Z ECMWF CONTINUES AS A
SLOW OUTLIER WITH THE EASTERN TROUGH INITIALLY...BUT COMES BETTER
INTO PHASE WITH TIME. THE 00Z CANADIAN WAS ALSO IN LINE WITH THE
GFS.
THE 00Z UKMET WAS THE OUTLIER THIS PERIOD IN MOVING THE TROUGHING
ACROSS THE GREAT LAKES QUICKER TO THE EAST.

BURKE/ROTH