INVEST 93L Comments Thread #2

[Stratosphere747]

Well I'm sure that AFM is most likely gone for the evening, unless he is working a overnight shift.

After reading his input, if anything were to come out of 93, not sure if we should look for a split from the current convection, or something building by itself behind it.

[Matt-hurricanewatcher]

I would watch for convection to start forming on the wave its self, as it is starting to move back over water. See what happens as the wave/cyclone pushs back out is it forces the air/moisture upwards into convection. I would watch that...Forget the MCC.

[Air Force Met]

Ok, thanks for the response, AFM. I kinda understand what you're saying.

*grabs her Meteorology for Dummies book*

Mesoscale...meaning something on a smaller scale...50 to a couple hundred miles or so. They con be complexes of thunderstorms...squall lines...etc...but are not systems that are stacked and encompassing different levels of the atmosphere (even though they may extend into them). Synoptic scale is larger and encompasses several hundred miles and can be thought of as a system that interacts with all levels of the environment...like a sfc low with a cold front or a hurricane.

[Air Force Met]

I would watch for convection to start forming on the wave its self, as it is starting to move back over water. See what happens as the wave/cyclone pushs back out is it forces the air/moisture upwards into convection. I would watch that...Forget the MCC.

I concur with that. The current convection is actually a negative because it is pulling energy out of the system.

FWIW...you can really see the "LINE" of convection now along the outflow boundry on the GHCC loop...especially on the 0501Z image. NOw all the tops are beginning to warm except on the southern edge of the line...which is along the coast.

[Matt-hurricanewatcher]

I agree air force met. I see...The wave by the nhc/two is at around 88 or 89 west moving westward. Should take another 24 hours. We see hundreds of these like events over this area every year that flare up then down. The wave is where we need to watch.

http://www.nhc.noaa.gov/tafb/ATSA_18Z.gif

[southerngale]

Ok, thanks for the response, AFM. I kinda understand what you're saying.

*grabs her Meteorology for Dummies book*

Mesoscale...meaning something on a smaller scale...50 to a couple hundred miles or so. They con be complexes of thunderstorms...squall lines...etc...but are not systems that are stacked and encompassing different levels of the atmosphere (even though they may extend into them). Synoptic scale is larger and encompasses several hundred miles and can be thought of as a system that interacts with all levels of the environment...like a sfc low with a cold front or a hurricane.

Ok, I got it now. Thanks AFM...I really appreciate you explaining it to me.

[Stratosphere747]

I would watch for convection to start forming on the wave its self, as it is starting to move back over water. See what happens as the wave/cyclone pushs back out is it forces the air/moisture upwards into convection. I would watch that...Forget the MCC.

I concur with that. The current convection is actually a negative because it is pulling energy out of the system.

FWIW...you can really see the "LINE" of convection now along the outflow boundry on the GHCC loop...especially on the 0501Z image. NOw all the tops are beginning to warm except on the southern edge of the line...which is along the coast.

This was a reason for my earlier question. If any development were to occur, are we looking for a split from the latest blow up, or something building behind it?

[Air Force Met]

Ok, thanks for the response, AFM. I kinda understand what you're saying.

*grabs her Meteorology for Dummies book*

Mesoscale...meaning something on a smaller scale...50 to a couple hundred miles or so. They con be complexes of thunderstorms...squall lines...etc...but are not systems that are stacked and encompassing different levels of the atmosphere (even though they may extend into them). Synoptic scale is larger and encompasses several hundred miles and can be thought of as a system that interacts with all levels of the environment...like a sfc low with a cold front or a hurricane.

Ok, I got it now. Thanks AFM...I really appreciate you explaining it to me.

N/P.

OK...night night. Gotta rest for tmorrow's rain

[Air Force Met]

This was a reason for my earlier question. If any development were to occur, are we looking for a split from the latest blow up, or something building behind it?

MOre behind it along the actual wave itself. The current blow up should die off by morning....if not sooner.

[Stratosphere747]

This was a reason for my earlier question. If any development were to occur, are we looking for a split from the latest blow up, or something building behind it?

MOre behind it along the actual wave itself. The current blow up should die off by morning....if not sooner.

LOL...Thanks for the quick reply...

Get your butt in bed now..

[Matt-hurricanewatcher]

I would watch for convection to start forming on the wave its self, as it is starting to move back over water. See what happens as the wave/cyclone pushs back out is it forces the air/moisture upwards into convection. I would watch that...Forget the MCC.

I concur with that. The current convection is actually a negative because it is pulling energy out of the system.

FWIW...you can really see the "LINE" of convection now along the outflow boundry on the GHCC loop...especially on the 0501Z image. NOw all the tops are beginning to warm except on the southern edge of the line...which is along the coast.

This was a reason for my earlier question. If any development were to occur, are we looking for a split from the latest blow up, or something building behind it?

I would watch by tomarrow night when the wave starts moving into the BOC. At first the western side will start poping with convection as the air flow's over up the wave(Like a air mass like front)then watch if the convection can hold on=work a cirulation down to the surface. See the tropical wave is a broad/enlongated area of low pressure so thats the area you have to watch for development.

[SouthFloridawx]

Your 100 percent right Air forcemet. People its a outflow boundry and maybe day time heating which makes the air mass unstable causing air to rise...In which causes convection/thunderstorms to blow up on land durning the day. Then move over water at night when the water is warmer then the land. Don't expect development from this system intill the wave moves back into the BOC by 24 hours/Monday afternoon. Then theres a slight chance but this year is proven to be very unfaverable to tropical cyclones unlike last year.

Airforcemet you knowledge is amazing.

I wasn't expecting any development from any certain blob. We were merely watching this wave as it moves closer to the BOC. Experience creates knowledge and thus watching it's every movement can be hum-drum and boring to some people but, to others it is interesting because they learn something along the way. I am not calling for anything to develope.

[Noah]

Man, Sarasota getting clobbered with rain and thunderstorms all day.. what invest is offecting us.. rained all last night too..thundering all night keeping me up

That invest would be the northern-most part of Ex-93L or the
northern part of the blob that was once 93L...the rest of
Ex-93L, it's central and southern parts are over the
Yucatan and exiting it into the Bay Of Campeche.
A tropical wave, the northern part of Ex-93L crossed
Florida today, and that helped fuel our thunderstorms
today. There were several reports of tropical storm force
wind gusts over 40 mph in the Tampa Bay area and likely
similar conditions occurred with those thunderstorms
near Sarasota.

Yeah seemed like some TS force winds came through, lights were flickering. The sky looked so angry, it was creepier than your typical florida afternoon storm.

[Aquawind]

Thanks ~93L! We appreciate the enhanced precip here.. Were nearly normal now! Bye Bye ~93L!

[Stratusxpeye]

Thank you northern 93L. We had about an inch of slow falling rain yesterday, not much of a downpour. Was good for the trees and grass. I'll take any rain I can get. Our ponds and retention ponds are starting to look a little more normal. Still drier than normal but were catching up

[SouthFloridawx]

AirForceMet,

I have a couple of questions for you regarding what happend last night with the area of convection over the Yuck and the BOC.

What I'm trying to understand possibly in more simple terms or for people such as myself who don't have as much experience/training in meteology.

I noticed that you called for the thunderstorm activity to die out and quickly head over to the mexican coastline. What did you notice there that others had not seen that caused this situation to happen? Why did you think that the convection was not caused by the tropical wave as opposed to other more normal features over the yuck/boc.

Also a second question regarding the tropical wave thread in the atlantic just east of the antillies.

you have to remember, a lot of times the reason there is convection is because of the interaction with the wave axis and the westerly winds.

Do the westerlies provide a good environment for ventilating the storms or just the interaction with the wave cause increased instability and thus increased convection asociated with the wave?

[Air Force Met]

AirForceMet,

I have a couple of questions for you regarding what happend last night with the area of convection over the Yuck and the BOC.

What I'm trying to understand possibly in more simple terms or for people such as myself who don't have as much experience/training in meteology.

I noticed that you called for the thunderstorm activity to die out and quickly head over to the mexican coastline. What did you notice there that others had not seen that caused this situation to happen? Why did you think that the convection was not caused by the tropical wave as opposed to other more normal features over the yuck/boc.

Also a second question regarding the tropical wave thread in the atlantic just east of the antillies.

you have to remember, a lot of times the reason there is convection is because of the interaction with the wave axis and the westerly winds.

Do the westerlies provide a good environment for ventilating the storms or just the interaction with the wave cause increased instability and thus increased convection asociated with the wave?

Sorry I didn't see your question sooner...and we were gone yesterday...

I can answer your questions with a situation from my past. The mets on the boards are great...but most haven't SPENT a lot of time forecasting IN the tropics...they have spent a lot of time forecasting for them...but not for them...IN them. That makes a big difference...when you are IN the tropics (and I'm talking about sitting in a jungle...at 10N in Panama...or sitting in the middle of the rainforest in Belize...or the high desert in Guatemale (Salama)).

I've spent a lot of time IN them...because I am in the military....and I did it at a time in my career when you did not have access to the internet (there wasn't one) and there wasn't a whole bunch of models....and you felt like you won the lotto if you got a 6 hour old satellite image that was b&w and grainy. So...I learned to have to rely on three things...a low level streamline chart and an upper level streamline chart (200-300mbs) and climo. If I had those...I was good to go and could make a really good forecast.

So...those westerly winds act as shear and enhance outflow...and because a tropical wave creates sfc convergence...and with outflow aloft...you get convection. If you have some divergence associated with your westerly winds...now you have TWO means of divergence aloft...directional (because the flow is going east at 200mb and the wave is moving west) and divergent...which acts to create lift.

So...to answer your other question...what I was seeing was 1) Climo. Tstms happen on the Yuc. Penn alot in the PM. It occurs all the time. 2) The introduction of a wave increases sfc convergence...this adds to the instability. 3) You had divergence aloft as seen in WV imagery and IR sat. 4) The convection (the BIG blow up after sunset) was moving TOO fast to be associated with the wave...and formed at the same time as the collapse of two other convective complexes. That was a sign to me that is was NOT associated with the wave alone...there HAD to be something else.

The first big blow-up over the Yucatan was something I would normally expect to happen in the tropics. Strong convergence at the sfc with the heating over land...combined with good divergence aloft willalways lead to a initiation of convection...but it will cease after sunset. Colliding outflow boundries often create propogating tstms in the tropics...especially under divergent upper level winds....but forecasting those is difficult.

Had I been on a remote in the Yucatan with the military 10 years ago...and had nothing but a streamline of the 925mb chart and the 250mb...and had seen the same setup as the 2nd...I would have called for a blow-up of convection...and would have forecasted a dissipation shortly after sunset....you never know when an outflow boundry will set up...you can mention it...but whether or not it will happen is up to a roll of the dice.

Hope this helps.

[SouthFloridawx]

Thanks....