ATL: INVEST 92L - Discussion

[Stormcenter]

Looks stationary to me.

['CaneFreak]

Respectfully disagree with both of you. There is no low level vorticity in that area nor any concentrated mid level vorticity.

850 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=
700 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=
500 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

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.

Agree and convection appears to be working its way toward that area.

[cycloneye]

Here is this mornings discussion of 92L by Dr Jeff Masters:

Tropical wave 92L crossed over Mexico's Yucatan Peninsula overnight, and the center of the disturbance is now located in the Gulf of Mexico along the west coast of the Yucatan Peninsula. Satellite loops show that 92L has a well-developed surface circulation, but there are no heavy thunderstorms near the center. A moderate-sized region of heavy thunderstorms does lie to the northeast and east of the center, over Cancun, Cozumel, and southwards to Belize. Wind shear is a moderate 10 - 20 knots over the the wave, which should allow slow development today. The hurricane hunter flight scheduled for today has been cancelled.

Forecast for 92L

The 12Z Friday SHIPS model forecast predicts that 92L will remain in an area of low to moderate wind shear through Saturday, and ocean temperatures will be a favorable 29 - 30°C. The topography of the Southern Gulf of Mexico's Bay of Campeche can aid in getting a storm spinning more readily, as well. Given these favorable conditions for intensification, 92L should be able to become a tropical depression by Saturday, and a tropical storm by Sunday. A trough of low pressure over the northern Gulf of Mexico will dip down by Sunday over the Central Gulf of Mexico, increasing the wind shear to a high 20 - 30 knots just to the north of 92L. This trough may also be able to pull the storm northwestwards to a landfall in Texas on Monday or Tuesday, as the 00Z Friday runs of UKMET and NAVGEM model predict. If 92L does follow this more northwesterly path, intensification into a strong tropical storm would be difficult, due to the high wind shear. An alternate scenario is presented by our two top-performing models, the European and GFS. They predict that 92L will take a nearly due west track, resulting in a landfall south of Tampico, Mexico on Monday. The storm would have more of an opportunity to strengthen in this scenario, since wind shear would be lower. Either scenario is reasonable, and residents of the Mexican and Texas Gulf Coast should anticipate the possibility of a tropical storm hitting the coast as early as Sunday night. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 92L a 50% of developing by Sunday, and a 60% chance of developing by Wednesday. I put these odds higher, at 70% and 80%, respectively.

[Dean4Storms]

Respectfully disagree with both of you. There is no low level vorticity in that area nor any concentrated mid level vorticity.

850 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=
700 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=
500 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

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.

Agree and convection appears to be working its way toward that area.

Does not mean that vorticity can't develop in an area of increasing convection.

[Portastorm]

A weak tropical storm hitting South Texas and then moving north through the state? That would be a dream come true for many of us. Hope it happens.

[Bailey1777]

question if the nhc really thought this was going to be more than 1 entity would they classify it as 2 seperate invest.

[GCANE]

Very unusual, core is actually heating up despite the lack of convection. Now at 3C.

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

Still has a strong boundary layer inversion at 2C.

If that erodes, this could pop very quickly.

['CaneFreak]

I'm not saying it can't but the odds are stacked highly against anything forming that far to the north. The vorticity is already concentrating itself much farther to the south at this time. It is looking much more likely in my opinion that a weak to moderate TS makes landfall in central/northern Mexico on Sunday.

Does not mean that vorticity can't develop in an area of increasing convection.

[GCANE]

Going thru the 3hr steps on 200mb vorticity, its pretty clear the ULL is weakening.

http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

[Javlin]

Going thru the 3hr steps on 200mb vorticity, its pretty clear the ULL is weakening.

http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

Never thought of looking @ an ULL that way Now could that imply a transition of some sorts?could be interesting possibily.

also note the convection to the NNE is being pulled viva the ULL ATTM.

[GCANE]

Going thru the 3hr steps on 200mb vorticity, its pretty clear the ULL is weakening.

http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

Never thought of looking @ an ULL that way Now could that imply a transition of some sorts?could be interesting possibily.

also note the convection to the NNE is being pulled viva the ULL ATTM.

The convection is key in eroding the ULL. Once the black turns to white, the ULL will be gone.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

[Javlin]

Going thru the 3hr steps on 200mb vorticity, its pretty clear the ULL is weakening.

http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

Never thought of looking @ an ULL that way Now could that imply a transition of some sorts?could be interesting possibily.

also note the convection to the NNE is being pulled viva the ULL ATTM.

The convection is key in eroding the ULL. Once the black turns to white, the ULL will be gone.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

Thks again GC for the education.I was wondering the how the ULL that was off the EC dissolved so quickly while this one here perserveered for so long.And then a brief window of no hosilities.

[Stormcenter]

Looks better now than it ever has before. IMO

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

[wxman57]

Respectfully disagree with both of you. There is no low level vorticity in that area nor any concentrated mid level vorticity.

850 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=
700 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=
500 mb vorticity: http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

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.

Agree and convection appears to be working its way toward that area.

Those posts were from yesterday. There's a clear surface low now near 21.5N/91.5W. Convection is being displaced well to the NE and E by wind shear. If the wind shear lets off then we'll have TD 6 and/or Fernand within 24hrs.

[GCANE]

Thks again GC for the education.I was wondering the how the ULL that was off the EC dissolved so quickly while this one here perserveered for so long.And then a brief window of no hosilities.

Your welcome Javlin. I remember seeing a very similar situation a couple years ago a few miles farther north in the GOM.

[Rgv20]

Morning Discussion out of the NWS in Brownsville.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...CONSIDERABLE
UNCERTAINTY REMAINS WITH RESPECT TO THE DISTURBANCE OVER THE
YUCATAN PENINSULA AND ITS EVENTUAL TRACK AND EVOLUTION.
THEREFORE...HAVE MADE LITTLE CHANGES FOR THE LONG TERM AND HAVE
TAKEN THE PERSISTENCE APPROACH OVER ANY ONE MODEL SOLUTION.

Morning Discussion out of the NWS in Corpus Christi.

CONSIDERABLE UNCERTAINTY THEN DEVELOPS IN THE FORECAST MONDAY
THROUGH WEDNESDAY...IN PARTICULAR WITH THE DISTURBED WEATHER
CURRENTLY OVER THE YUCATAN AND ITS DEVELOPMENT...IF ANY...AND
MOVEMENT THROUGH THE GULF OF MEXICO. SEVERAL QUESTIONS STILL EXIST
INCLUDING HOW MUCH ENERGY IS PULLED NORTH INTO THE NORTHERN GULF
COAST BY THE TROUGH...AND WHETHER A PORTION OF THE ENERGY/DISTURBED
WEATHER CONTINUES WESTWARD AS AN INVERTED TROUGH. ALSO...WHETHER OR
NOT A WELL DEFINED CLOSED CENTER EVER DEVELOPS LEADS TO A GREATER
RANGE OF SCENARIOS. UNTIL THE EVOLUTION OF THIS SYSTEM BECOMES MORE
CLEARER IT IS TOO SOON TO HAVE A HIGH DEGREE OF CONFIDENCE IN THE
FORECAST BEYOND SUNDAY.

FOR NOW WILL CONTINUE WITH THE THOUGHT THAT AT LEAST A PORTION OF
THE INVERTED TROUGH AND DEEPER TROPICAL MOISTURE WILL MAKE IT INTO
MEXICO/TEXAS LATE MONDAY INTO TUESDAY...WITH SLIGHT CHANCE POPS FOR
NOW TUESDAY THROUGH THURSDAY GIVEN THE DEGREE OF UNCERTAINTY. HAVE
COORDINATED WITH TAFB AND SURROUNDING OFFICES ON WIND AND SEA
FORECAST OFFSHORE...WITH A NORTHEAST WIND AND SLIGHTLY HIGHER SEAS
SHOWN SUNDAY THROUGH MONDAY. SLIGHTLY COOLER HIGH TEMPS ARE FORECAST
TUESDAY THROUGH THURSDAY. FINALLY...IT SHOULD BE STRESSED THAT
"SPAGHETTI MODEL PLOTS" AVAILABLE OF THE INVEST LOW SHOULD BE USED
WITH ABUNDANT CAUTION AT THIS TIME DUE TO THE CURRENTLY DISORGANIZED
NATURE OF THE AREA OF DISTURBED WEATHER. PLEASE REFER TO THE
NATIONAL HURRICANE CENTER FOR THE LATEST OUTLOOK ON THIS SYSTEM.

[Alyono]

is becoming better organized now. No question about it.

Still, with the strong shear expected in the west Gulf in about 48 hours, this would only be a TD or a weak TS. The Canadian seems clueless as it is developing the system despite a very high shear environment

[hurricanekid416]

It has a llc but it's a naked swirl

['CaneFreak]

Nope. Time stamps on BOTH posts was 2-3 hours ago. However, thanks for the clarification.

Those posts were from yesterday. There's a clear surface low now near 21.5N/91.5W. Convection is being displaced well to the NE and E by wind shear. If the wind shear lets off then we'll have TD 6 and/or Fernand within 24hrs.

[Rgv20]

Those posts were from yesterday. There's a clear surface low now near 21.5N/91.5W. Convection is being displaced well to the NE and E by wind shear. If the wind shear lets off then we'll have TD 6 and/or Fernand within 24hrs.

Even if it gets going it looks like Wind Shear is going to be rather strong North of 24N by Mid day/Evening Saturday.

Question wxman57 how reliable are Wind Shear forecast (GFS,NAM,ECMWF) in the 0-72hour range?