ATL: INVEST 92L - Discussion

[ozonepete]

I have to call it a night, but on my last look it looks like that little ULL in the central Gulf is winning the game. It's pulling a lot of the energy into itself from the northern part of this disturbance, which prevents anything from happening there. The southern end of the elongated disturbance (the part over central Yucatan) is not developing nor is it going anywhere; it simply doesn't have enough energy from the original disturbance to maintain itself: I don't see any MLC developing down there and most of the convection is moving due south and dissipating. In the end it looks like the models were right: the uncomplicated solution is that the energy would keep getting stretched out from north to south and that prevented either possibility, a north or south development, from getting going. There is a very small chance that the ULL could start firing convection and drift around for a while and then develop into something, but then I also have a bridge in Brooklyn to sell you if you're interested.

[CrazyC83]

One thing worth noting: if this had developed into a depression or weak storm approaching the Yucatan, the situation would be identical right now. This is a VERY complicated setup. I'm still leaning towards a system stalling out in the Bay of Campeche.

[Rgv20]

Latest 3z CIMSS 850MB Vorticity is looking rather strong in the NW Yucatan. Going to be interesting if 92L tries to develop tomorrow and it looks like the 0zGFS tries to split the 850MB Vorticity on Saturday Morning.



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[HurriGuy]

Curious to see what the morning holds and if the convection starts to fire up again. as of now this system looks nothing more than elongated wave.

[MGC]

Yep, that ULL is doing an good job of streaching that wave out. Kinda reminds me of that toy that my kids use to have that could streach. ULL looks to be slowly retrograding so maybe that will help the blob in the eastern GOM get going, kinda like Andrea this June....MGC

[southerngale]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT FRI AUG 16 2013

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM ERIN...LOCATED WEST OF THE SOUTHERNMOST CAPE VERDE ISLANDS.

A BROAD LOW PRESSURE SYSTEM...ACCOMPANIED BY A LARGE AREA OF
DISORGANIZED CLOUDINESS AND SHOWERS...IS LOCATED OVER THE NORTHERN
YUCATAN PENINSULA OF MEXICO. LITTLE OR NO DEVELOPMENT OF THE LOW IS
EXPECTED WHILE IT REMAINS OVER LAND. HOWEVER...THERE IS POTENTIAL
FOR DEVELOPMENT ONCE THE DISTURBANCE MOVES OVER THE GULF OF MEXICO
LATER TODAY. AFTER THAT TIME...THE LOW IS FORECAST TO MOVE TOWARD
THE CENTRAL GULF OF MEXICO WHERE UPPER-LEVEL WINDS WOULD ONLY FAVOR
SLOW DEVELOPMENT...IF ANY. THIS SYSTEM HAS A MEDIUM CHANCE...
50 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48
HOURS...AND A HIGH CHANCE...60 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS. AN AIR FORCE RESERVE RECONNAISSANCE
AIRCRAFT IS SCHEDULED TO INVESTIGATE THE DISTURBANCE LATER TODAY...
IF NECESSARY.

[EastCoastlow]

The storm and ULL will be interacting with a mid-latitude trough Potential vorticitiy trough interactions with storms are tough to anticipate regarding intensity. In addition the ULL will be interacting with the trough to further complicate things.

[GCANE]

This may pop once it gets back over the water

OHC will be very high for the system tomorrow and Sunday

http://rammb.cira.colostate.edu/product ... 150600.GIF


Warm core is surprising very well intact with a strong circulation from the boundary layer to mid troposphere

http://rammb.cira.colostate.edu/product ... 1308160314

http://rammb.cira.colostate.edu/product ... 4_VGRD.GIF


Two factors holding this back is the ULL and boundary layer inversion

CAPE is not too bad, especially off the NW shore of the Yucatan

http://www.twisterdata.com/data/models/ ... URFACE.png


It may come together pretty quickly once the inversion is eroded

Enhanced convection, by way of a couple strong hot towers, could then take out the ULL

http://www.atmos.washington.edu/~ovens/ ... nhanced+24


A good looking anti-cyclone is sitting very close by

http://tropic.ssec.wisc.edu/real-time/a ... wg8shr.GIF

[Dean4Storms]

Wow, woke up and see the ULL still dropping SSW, I thought it was expected to rapidly move off NNE over night?

Is it not true that an ULL SW of a surface low is one of the best positions for a nearby ULL to be in regards to helping vent a TC?

[caneman]

I think so Dean - the problem is we don't have a developed system and would appear to me the focal point would be the blob to its East. Just doesn't seem like it would have enough time to get going.

[Dean4Storms]

I'm sort of ignoring much of the guidance at this point. All the moisture and surge of this TW is now in the eastern Gulf, see WV imagery. I could easily see a system developing to the north, NE or even east of that ULL if convection there begins to ramp up today just like what went down with Andrea in early June.

[caneman]

You may be right. Either way, we're in store for a boat load of more rain it looks like.

[Dean4Storms]

That LL swirl seen last night near Merida is now off the NW corner of the Yucatan out over the upper BOC, with that ULL dropping that way it is toast and under dry air. I think the area to watch today is just north of the Yucatan Peninsula where convection is firing this morning.

[wxman57]

I had said SW winds at 50-60 kts, not shear, as the system moves north toward the coast. The map posted above is current shear, not shear in 48 hrs. Maps below indicate future winds and shear. 50kt winds off the LA coast and 50+ kts shear offshore. 30+ kts shear down to the central Gulf by Saturday. Anything in the central Gulf is toast.

So where are these SW winds at 50-60 knots? All 3 charts you posted here show shear in knots - they don't show any winds in knots at any level. You labeled the first chart 200mb winds but it's a shear chart. Also, why would high 200mb winds matter if there's no shear in the low to mid-levels? Also, the middle chart shows the GFS shear forecast from 12Z this morning for --- 12Z this morning. That's already come and gone. Shear has been dropping a lot since then and so have shear forecasts. The more recent forecasts have favorable shear of 5 to maybe 15 knots all the way to near the coast.

Just got back here. The charts showed shear from 850mb to 200mb, not 200mb. I posted the wrong links for the upper wind, but you can check them out at tropicaltidbits.com. GFS still has 850mb-200mb shear of 35-50 kts from the central gulf to the LA coast, and SW winds of 50 kts at 200mb. Very high shear north of 25N.

[cycloneye]

8 AM.

SATELLITE IMAGES INDICATE THAT AN AREA OF LOW PRESSURE HAS MOVED
OFFSHORE OF THE YUCATAN PENNISULA AND OVER THE SOUTHWESTERN GULF OF
MEXICO. ALTHOUGH THE SHOWER AND THUNDERSTORM ACTIVITY IS CURRENTLY
DISORGANIZED AND LOCATED WELL TO THE EAST AND NORTHEAST OF THE LOW
CENTER...ENVIRONMENTAL CONDITIONS COULD BECOME MORE FAVORABLE FOR
DEVELOPMENT IF THE LOW MOVES TOWARD THE WEST OR WEST-NORTHWEST OVER
THE NEXT COUPLE OF DAYS. INTERESTS IN THE CENTRAL AND WESTERN GULF
OF MEXICO SHOULD MONITOR THE PROGRESS OF THE SYSTEM THROUGH THE
WEEKEND. IF THE LOW TAKES A MORE NORTHWARD TRACK...HOWEVER...IT
WOULD MOVE INTO A LESS CONDUCIVE ENVIRONMENT FOR DEVELOPMENT. THIS
SYSTEM HAS A MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS...AND A HIGH CHANCE...60
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS.
THE AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT MISSION SCHEDULED FOR
TODAY HAS BEEN CANCELLED.

[Dean4Storms]

8 AM.

SATELLITE IMAGES INDICATE THAT AN AREA OF LOW PRESSURE HAS MOVED
OFFSHORE OF THE YUCATAN PENNISULA AND OVER THE SOUTHWESTERN GULF OF
MEXICO. ALTHOUGH THE SHOWER AND THUNDERSTORM ACTIVITY IS CURRENTLY
DISORGANIZED AND LOCATED WELL TO THE EAST AND NORTHEAST OF THE LOW
CENTER...ENVIRONMENTAL CONDITIONS COULD BECOME MORE FAVORABLE FOR
DEVELOPMENT IF THE LOW MOVES TOWARD THE WEST OR WEST-NORTHWEST OVER
THE NEXT COUPLE OF DAYS. INTERESTS IN THE CENTRAL AND WESTERN GULF
OF MEXICO SHOULD MONITOR THE PROGRESS OF THE SYSTEM THROUGH THE
WEEKEND. IF THE LOW TAKES A MORE NORTHWARD TRACK...HOWEVER...IT
WOULD MOVE INTO A LESS CONDUCIVE ENVIRONMENT FOR DEVELOPMENT. THIS
SYSTEM HAS A MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS...AND A HIGH CHANCE...60
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS.
THE AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT MISSION SCHEDULED FOR
TODAY HAS BEEN CANCELLED.

It was right where I said it was last nite in reference to Best Track's position when someone attempted to tell me otherwise. It was just east of Merida.

[Gustywind]

8 AM Discussion.

TROPICAL WAVE AND THE ASSOCIATED LOW HAS MOVED INTO THE GULF OF
MEXICO AT 16/0900 UTC EXTENDING FROM 14N90W THROUGH THE 1009 MB
LOW NEAR 21N91W OVER S MEXICO TO 15N91W. BROAD AREA OF SCATTERED
SHOWERS WITH EMBEDDED ISOLATED THUNDERSTORMS COVERS THE SE GULF
OF MEXICO S OF LINE FROM TAMPA FLORIDA TO THE TROPICAL WAVE NEAR
24N91W AND IN THE FAR W CARIBBEAN W OF 86W. ENVIRONMENTAL
CONDITIONS COULD BECOME MORE FAVORABLE FOR DEVELOPMENT IF THE
LOW MOVES TOWARD THE WEST OR WEST-NORTHWEST DURING THE NEXT
COUPLE OF DAYS. INTERESTS IN THE CENTRAL AND WESTERN GULF OF
MEXICO SHOULD MONITOR THE PROGRESS OF THE SYSTEM THROUGH THE
WEEKEND. IF THE LOW TAKES A MORE NORTHWARD TRACK...HOWEVER...IT
WOULD MOVE INTO A LESS CONDUCIVE ENVIRONMENT FOR DEVELOPMENT.
THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS...AND A HIGH CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT FIVE DAYS. THE AIR FORCE
RESERVE RECONNAISSANCE AIRCRAFT MISSION SCHEDULED FOR TODAY HAS
BEEN CANCELLED.

[wxman57]

The place to watch for development is north of the western Yucatan. Near about 22.5N/89.5W. That part of the disturbance isn't heading north into higher shear, it's heading WNW-NW where shear is much lighter - at least for 24-36 hrs. Then the GFS is indicating 40-50 kts wind shear from Tampico northward within 100 miles of the coast.

[jeff]

Agree with Wxman... Low level swirl is there WNW of the NW tip of the Yucatan...but currently void of any deep convection. That is what should be followed all the stuff north and east is just tropical moisture interacting with the upper level trough.

[cycloneye]

12z Best Track.

AL, 92, 2013081612, , BEST, 0, 214N, 913W, 25, 1009, LO