Atlantic Tropical Action 2013 - Part 2

[wxsmwhrms]

95L appears to be under some northwesterly shear.. Looks like mid-level circulation may be over water now with all the convection still over the Yucatan. Tough to be sure though... anyone else see a structure moving southeastward through all the convection up to the northeast of 95L?  Can't tell if this is an arc cloud/gravity wavy/frontal boundary? Its not moving too fast.

 

 

 

Mike, I do see the structure you're seeing, but as you say, not sure what it is.  Not moving very quickly.  The shear vector over the system is currently N/NW which is likely why the system is currently lopsided more to the E.  However, the models show it becoming more northeast and eventually easterly over the next 12-36 hours.  If that does indeed happen, one would expect a more favorable setup for convection to wrap around the west side of the circ.  It is already a pretty robust circulation with MSLP already down in the 1005 mb range.  I'm guessing the center on sat imagery to be somewhere in the general area of 21.2/91.2?

[phil882]

Radar is showing some cells firing closer to the center along the coast of the Yucatan.

 

[wxmeddler]

Radar is showing some cells firing closer to the center along the coast of the Yucatan.

 

I was just looking at this, came to post it on here and you already ninja'd it.

[tmagan]

Obviously, we don't have any observed soundings in the area, but the dry air currently on the NW side of the system must be in relatively limited layers in the mid/upper levels, given that the sounder retrievals show that PW values are 2-2.5".  That may allow what dry air does exist to mix out.  Given that the shear vector is supposed to turn more easterly, eventually convection could start to wrap more around the west side.  We'll see.

Here is the closest sounding in the area for 12Z 18 September for Merida, MX.

[wxmx]

Naked swirl around 21.1N 91.3W

[Ed Lizard]

SHIPS now using double probabtion secret official track, keeps it offshore through 5 days, slows it down to 3-5 knots the last couple of days.  LGE gets a Cat 1, (D)SHIPS, not quite.

 

 

*   ATLANTIC SHIPS INTENSITY FORECAST       *
                    * GOES AVAILABLE,       OHC PROXY USED      *
                    *      INVEST  AL952013  09/18/13  12 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    25    26    28    30    32    35    38    43    48    53    57    58    60
V (KT) LAND       25    29    31    33    34    37    40    46    51    55    59    61    63
V (KT) LGE mod    25    28    29    31    32    36    40    45    52    60    67    74    78
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)        20    14    12    14    14    11    15     6     8     3     4     5     7
SHEAR ADJ (KT)    -4     0    -3     0     1     0    -1     1     0    -2     1    -2     1
SHEAR DIR        359     5   343   339   348    16    11   355    16   271   318   246   359
SST ©         28.9  29.0  28.9  28.9  28.9  29.0  29.0  29.0  28.9  29.0  29.0  29.1  29.0
POT. INT. (KT)   150   151   150   150   150   151   149   147   146   148   148   150   149
 

[Tom]

looking for some information not a forecast, is the euro taking this system up the eastern seaboard mid to late next week?  I have a tuna trip off the NJ coast to canyons and hoping for decent weather. (next Friday)

[Ed Lizard]

Naked swirl around 21N

 

Over a degree North of the official 7 am CDT position.

[wxmx]

12z Euro inits around 21N...but then moves it just S of due W (24h) and WNW(48h) to a near landfall close to Tampico before cold front  shoves it SE

[Ed Lizard]

looking for some information not a forecast, is the euro taking this system up the eastern seaboard mid to late next week?  I have a tuna trip off the NJ coast to canyons and hoping for decent weather. (next Friday)

 

Now sure whether some part of 95L involved (I think some of it is, actually)  but a decent coastal storm per 0Z Euro.  new Euro less than 30 minutes away

[wxsmwhrms]

The more I look at the differing model solutions, and how 95L is evolving today, the more complex and low confidence this looks.  The models are in semi-decent agreement that the system will generally move WNW from where it is now in the general direction of Tampico the next couple of days, and overall conditions look decent for development especially given how low the pressures are.  However, where exactly the best LLC will set up given the lack of convection close to the center now, and the uncertainty in the location of best low level vorticity makes even this evolution quite uncertain.

 

Beyond that, there is almost no model agreement either between the models or within their own run to run consisency on how the upper trough will evolve - with the GFS being weakest/fastest and UK slowest/deepest.  The 12Z Euro looks to have actually trended toward the UK aloft - but because of subtle differences in where the best low level vorticity with 95L ends up in a few days you have the difference between a baroclinically enhanced 95L making a robust landfall near MOB on the UK versus a strung out mess on the EC with the 95L vort max back along the tail end and drifting E in the central Gulf days 6-7. 

[Ginx snewx]

Now sure whether some part of 95L involved (I think some of it is, actually) but a decent coastal storm per 0Z Euro. new Euro less than 30 minutes away

Dr No

[Ed Lizard]

Dr No

I can see text data from the Euro, I know Austin gets 3 1/2" of rain with no help at all from the tropics, other than a mT airmass ahead of the front, HOU gets about 1 1/2", but I can't get even free graphics until 2 pm CDT, and enhanced AccuWx PPV graphics until almost 3 pm CDT.

 

Just a quick glance, what appears to be the exposed center is moving pretty quickly,  Weak and West might be the way to go.

 

Euro leaves something behind at Day 10, rather weak,  sort of in center of the re-established sub-tropical ridge and probably in no hurry to move in any particular direction

 

[GaWx]

I can see text data from the Euro, I know Austin gets 3 1/2" of rain with no help at all from the tropics, other than a mT airmass ahead of the front, HOU gets about 1 1/2", but I can't get even free graphics until 2 pm CDT, and enhanced AccuWx PPV graphics until almost 3 pm CDT.

 

Just a quick glance, what appears to be the exposed center is moving pretty quickly,  Weak and West might be the way to go.

 

Euro leaves something behind at Day 10, rather weak,  sort of in center of the re-established sub-tropical ridge and probably in no hurry to move in any particular direction

 

 

 12Z Euro moves 95-L due westward along 20N til tomorrow evening. Then it sort of stalls and drifts NW just offshore and gets down to 1003 mb. Then, on Sunday, it moves NEward as a hybrid to the FL panhandle on Monday and to offshore SC, where it very sluggishly moves ESEward Tue-Fri due to high pressure to the north/NW of it as an upper trough barely gets it. I do wonder if it would actually stall in that situation.

[wxsmwhrms]

BTW, the 12Z HWRF takes a cat 2 into AQQ in 5 days after having a TS approach TAM.  FWIW (which is probably not much).

[GaWx]

Fwiw, geneses have been near average for Sep. since 1995 during MJO phase 4 (where it is now), but it has been much quieter on average during phase 5 though Humberto of 2007 originated during phase 5 fwiw.

 

Edit: Actually, it probably now is already in phase 5.

[icebreaker5221]

Obviously, we don't have any observed soundings in the area, but the dry air currently on the NW side of the system must be in relatively limited layers in the mid/upper levels, given that the sounder retrievals show that PW values are 2-2.5".  That may allow what dry air does exist to mix out.  Given that the shear vector is supposed to turn more easterly, eventually convection could start to wrap more around the west side.  We'll see.

 

Good point about the drastic differences between the WV and the PW retrievals.  No doubt that dry air is having a significant impact on 95L so far given the naked swirl / numerous outflow boundaries appearance, but at least a thin layer of dry air has better chances of mixing out faster. 

 

 

The more I look at the differing model solutions, and how 95L is evolving today, the more complex and low confidence this looks.  The models are in semi-decent agreement that the system will generally move WNW from where it is now in the general direction of Tampico the next couple of days, and overall conditions look decent for development especially given how low the pressures are.  However, where exactly the best LLC will set up given the lack of convection close to the center now, and the uncertainty in the location of best low level vorticity makes even this evolution quite uncertain.

 

Beyond that, there is almost no model agreement either between the models or within their own run to run consisency on how the upper trough will evolve - with the GFS being weakest/fastest and UK slowest/deepest.  The 12Z Euro looks to have actually trended toward the UK aloft - but because of subtle differences in where the best low level vorticity with 95L ends up in a few days you have the difference between a baroclinically enhanced 95L making a robust landfall near MOB on the UK versus a strung out mess on the EC with the 95L vort max back along the tail end and drifting E in the central Gulf days 6-7. 

 

 

A strung out mess sounds about right this season.

[wxsmwhrms]

The naked swirl looks to be diminishing, convection expanding/concentrating near where the low level sat winds would indicate the best turning is, centered near 20N, 91.5W.

[Ed Lizard]

Throwing out the Canadian and the NAM for a potential system in the Gulf always seems like a good idea.

 

 

DEEP SOUTH/GULF COAST
TROPICAL DISTURBANCE INTERACTING WITH UPPER TROUGH
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  NON-NAM COMPROMISE BY DEFAULT
CONFIDENCE:  BELOW AVERAGE

THE NATIONAL HURRICANE CENTER -- NHC -- GIVES THIS SYSTEM AN 80%
CHANCE OF BECOMING A TROPICAL CYCLONE OVER THE NEXT SEVERAL DAYS
AS IT DRIFTS ACROSS THE GULF OF MEXICO.  THE GUIDANCE DISTRIBUTION
CHANGED MARKEDLY AT 12Z, WITH CANADIAN/UKMET RADICALLY SLOWING
DOWN THEIR PROGRESSION TO THE NORTH.  CONSIDERING THE SLOWLY
AMPLIFYING RIDGE UPSTREAM, A SHARPER DOWNSTREAM TROUGH MAKES
SENSE, WHICH TOSSES THE WEAKER 12Z NAM FROM CONSIDERATION.

THE 00Z GLOBAL ENSEMBLE MEMBERS RESEMBLE THE 00Z GUIDANCE SPREAD,
WITH THE CANADIAN MEMBERS RACING OFF AHEAD OF THE GEFS/ECMWF
MEMBERS, WITH OVER HALF OF THE ENSEMBLE MEMBERS TAKING THE SYSTEM
BY THE MOUTH OF THE MISSISSIPPI SUNDAY MORNING.  HOWEVER,
ONE-SIXTH OF THE ENSEMBLE GUIDANCE HAS A MUCH SLOWER MOVING
SYSTEM, SIMILAR TO THE 12Z GUIDANCE.  ALL THINGS CONSIDERED, A
NON-CANADIAN COMPROMISE OVER THE LANDMASS NEAR MISSISSIPPI IS
PREFERRED -- MOST SIMILAR TO A 12Z GFS/12Z ECMWF COMPROMISE --
WHILE OUT IN THE GULF OF MEXICO A GENERAL MODEL COMPROMISE IS
CLOSE TO THE LATEST MEDIUM RANGE COORDINATION WITH NHC.
CONFIDENCE IS BELOW AVERAGE DUE TO THE LACK OF CONFIDENCE IN THE
00Z ENSEMBLE GUIDANCE DUE TO CHANGES IN THE 12Z CANADIAN SOLUTION
-- WHICH COULD BE REFLECTED IN THE 12Z CANADIAN ENSEMBLE GUIDANCE.
SEE NHC OUTLOOKS FOR MORE ON THIS SYSTEM'S STATUS AND EVOLUTION.


PAIR OF SYSTEMS MOVING THROUGH THE NORTHERN US
WEAK SHORTWAVE PASSING BY NEW ENGLAND LATE THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  GENERAL MODEL COMPROMISE
CONFIDENCE:  AVERAGE

THE GUIDANCE IS IN VERY GOOD AGREEMENT WITH THE THREE SYSTEMS
SWEEPING THROUGH THE NORTHERN TIER OF THE COUNTRY.  AS SUCH, A
GENERAL MODEL COMPROMISE IS ADVISED WITH AVERAGE CONFIDENCE
CONSIDERING THEIR PROGRESSIVE NATURE.

ROTH

 

 

[wxmx]

The naked swirl looks to be diminishing, convection expanding/concentrating near where the low level sat winds would indicate the best turning is, centered near 20N, 91.5W.

Yes, you can see the process in detail using high def visible imagery loop. The naked swirl is opening to the SE and relocating under the strong convection. Shear is weaker there.

[Amped]

So does the entire basin through the end of the month. Best we can hope for is the Caribbean or BOC in October.The will be very close to 1994 for lowest ACE in modern times.

[wxmx]

95L is probably a TD now.... Convection probably just needs to persist a bit more over the LLC.

[wxmx]

It actually looks pretty good. Excellent outflow in almost all quads...it's fair in the SW quad. Convection blowup and LLC are currently under ~10kts of shear

[wxsmwhrms]

It actually looks pretty good. Excellent outflow in almost all quads...it's fair in the SW quad. Convection blowup and LLC are currently under ~10kts of shear

 

I agree.  It's small, and the convective canopy is not yet large or particularly cold.  But not surprisingly given the low pressures and organized vorticity it looks well organized in visible with good banding, and as you say, the outflow is rapidly expanding.

[Srain]

I agree.  It's small, and the convective canopy is not yet large or particularly cold.  But not surprisingly given the low pressures and organized vorticity it looks well organized in visible with good banding, and as you say, the outflow is rapidly expanding.

[DopplerWx]

outflow looks great and dmax should bump this to a td tonight, storms already firing directly over the center and it just came offshore.

[DopplerWx]

meh. early intensity takes it to ts status by 36 hrs.

 

[wxsmwhrms]

95L is a tropical depression except for one minor problem - it doesn't have any thunderstorms over water.

[wxmeddler]

The LLC and MLC are still sheared with the LLC being NE of the MLC (which has the thunderstorms coming off the coast now).

[wxmeddler]

Microwave don't lie: