ATL: INVEST 92L - Discussion

[Nikki]

"An upper level ANTI-cyclone is forming over the western GOM now" could someone please explain what this will do for 92L?? Thank you....please be gentle I am a novice at this stuff...

[ozonepete]

Agreed. An upper level ANTI-cyclone is forming over the western GOM now and I would think that if this ends up missing the trough and heads west, it will have a whole lot better environment to work with and we could get a decent system out of this current mess. Do you think this misses the trough?

That's really difficult to answer right now. Due to the western anti-cyclone over Mexico and Texas and weak shortwave trough digging into the central GOM there's strong northward flow from low to mid-levels in the eastern Gulf and weak west to southwestward flow in the western Gulf. The weak shortwave trough has extended as far south into the Gulf as it's going to get and so it may not have much influence going forward. That could mean steering winds become too light to move this very much but I would lean towards the idea that there'll still be enough north to northeast flow left in the central Gulf to pick this up and bring it to the central Gulf coast. That's why the models are having trouble with this (like we all are, lol). Should it form an LLC tonight north of the Yucatan and deepen more quickly than forecast it's an easy track - straight to southeast Louisiana.

[Hurricane_Luis]

"An upper level ANTI-cyclone is forming over the western GOM now" could someone please explain what this will do for 92L?? Thank you....please be gentle I am a novice at this stuff...

I think an anticyclone will protect 92L from shear...As we saw yesterday when it was organising fast an anticyclone was right over 92L (Pro mets correct me if I'm wrong)

[Rgv20]

Afternoon discussion out of the NWS in Corpus Christi.

.LONG TERM (SATURDAY THROUGH THURSDAY)...GFS/ECMWF DETERMINISTIC
OUTPUT PROG A TRANSITION FROM AN UPPER RIDGE OVER THE WRN CONUS/
TROUGH OVER THE ERN CONUS...TO A PATTERN CHARACTERIZED BY THE UPPER
RIDGE WITH AN APPROXIMATELY E-W AXIS ACRS THE CNTRL CONUS. (THIS
PATTERN WL CONTRIBUTE TO SUBSIDENCE OVER THE CWA/MSA SATURDAY AND WL
NOT INTRODUCE PCPN SATURDAY FOR THE CWA/MSA DESPITE THE PROXIMITY OF
A WEAK FRONTAL BOUNDARY.) A DISTURBANCE IS LOCATED OVER THE
YUCATAN. THE MOST RECENT CYCLES OF THE ECMWF/GFS ARE GENERALLY
CONSISTENT WITH MOVG THE ASSOCIATED SFC LOW INTO THE CNTRL GULF BY
SATURDAY WITH THE ECMWF FURTHER SOUTH. THERE IS SIGNIFICANT
UNCERTAINTY REGARDING THE PSN OF THIS SYSTEM AFTERWARD. WL DEFER TO
THE ENSEMBLE MEAN WHICH KEEPS THE SFC FEATURE OVER THE SRN GULF/BAY
OF CAMPECHE. THIS SOLN SUGGEST THAT THE COPIOUS MSTR CURRENTLY OVER
THE ERN GULF/WRN CARIBBEAN (SPORT CIRA LAYERED PW TOTAL) WL ADVECT
WESTWARD AND ENTER THE WRN GULF BY LATE MONDAY THEN ACRS THE CWA. WL
MAINTAIN THE FCST OF ISOLD CONVECTION FOR THE CWA/MSA TUESDAY
THROUGH THURSDAY. HOT TEMPS EXPECTED SUNDAY/MONDAY FOLLOWED BY LOWER
MAX TEMPS OWING TO INCREASING MSTR/TROPICAL CONTINENTAL AIRMASS MOVG
NORTH OF THE CWA/MSA. MAX HEAT INDEX VALUES 105-109F ANTICIPATED FOR
SATURDAY YET MAX VALUES 100F OR LESS MONDAY-WEDNESDAY.

[rockyman]

There does appear to be a low-level spin forming on the northern coast of the Yucatan. Let's see if it persists.

[ozonepete]

"An upper level ANTI-cyclone is forming over the western GOM now" could someone please explain what this will do for 92L?? Thank you....please be gentle I am a novice at this stuff...

I think an anticyclone will protect 92L from shear...As we saw yesterday when it was organising fast an anticyclone was right over 92L (Pro mets correct me if I'm wrong)

Ok, let me clear it up a little bit with some annotated water vapor satellite images. On the first image you can see roughly what we have now; the second image has what we expect over the next couple of days (if most forecasts turn out right.) The anti-cyclone in the west is simply a HIGH pressure system that has clockwise winds around, that's why they are the opposite (anti) of cyclones or lows. Lows have counter-clockwise winds around them. So if this disturbance moves more westward soon (tonight and tomorrow) the flow around the anti-cyclone could pick it up and take it to southern Texas or northern Mexico. If the system forms north of the Yucatan and keeps moving slowly tonight and tomorrow, the second image scenario will be in place in a day or so: the anticyclone will move a little westward and the upper low will dissipate and the stronger steering flow towards Louisiana will prevail.

Current flow


Flow in 24-48 hours

[CYCLONE MIKE]

Nice detailed posts there ozonepete. Now what if this stays status quo and never develops, which is what I am thinking. Will moisture still get streamed up to us in se la or just get shoved into MX in a couple days.

[northjaxpro]

Excellent analysis Ozonepete

[ozonepete]

Btw, I threw in some basics for you, Nikki, because you asked.

And I should have added that of course any point in between northern Mexico and the LA/MS (even the FL panhandle) is possible depending on what the anti-cclone and trough do over the next few days. This is tough stuff. It's when even the models get confused.

[hurricanekid416]

What are the chances it becomes a tropical storm

[ozonepete]

Nice detailed posts there ozonepete. Now what if this stays status quo and never develops, which is what I am thinking. Will moisture still get streamed up to us in se la or just get shoved into MX in a couple days.

Thanks, Mike. Most of the models stream most of the moisture into LA even if this doesn't develop. That makes sense so far.

[ozonepete]

:uarrow:Excellent analysis Ozonepete

Thanx Jax.

[Nikki]

Btw, I threw in some basics for you, Nikki, because you asked.

And I should have added that of course any point in between northern Mexico and the LA/MS (even the FL panhandle) is possible depending on what the anti-cclone and trough do over the next few days. This is tough stuff. It's when even the models get confused.

Thank you I appreciate it!! I could literally sit for hours and ask questions about hurricanes...I really became interested in them after Katrina and Ike...

I just don't want to come across as a troll or a wish caster...I know first hand the devastation a hurricane can cause, I would never wishcast a hurricane anywhere, now rain is a different story

[ozonepete]

What are the chances it becomes a tropical storm

The NHC seems reasonable at 60% or "likely" that it becomes a TD or TS in the next few days. I have been on the fence, but I'm getting pretty sure that it makes it to TS by Saturday, mainly because the shear is really dropping.

[chrisnnavarre]

There does appear to be a low-level spin forming on the northern coast of the Yucatan. Let's see if it persists.

Yep, see that too....21.5N 88W something looks like it may be spinning up...lets see if it continues north and keeps spinning.

[Ntxw]

As wxman57 mentioned this morning two options are still fairly clear. If it heads north it's going to get ripped apart by roaring shear (deep trough over the eastern conus with 50+kts of shear) as it gets near the northern gulf. Staying in the BOC is the best chance of survival and maybe some development (questionable though) before hitting land likely MX.

[N2FSU]

Pretty impressive blowup of convection this evening NE of the Yucatan, near the western tip of Cuba.

[CYCLONE MIKE]

There does appear to be a low-level spin forming on the northern coast of the Yucatan. Let's see if it persists.

Yep, see that too....21.5N 88W something looks like it may be spinning up...lets see if it continues north and keeps spinning.

Very broad, nothing close to consolidating IMO

[ozonepete]

As wxman57 mentioned this morning two options are still fairly clear. If it heads north it's going to get ripped apart by roaring shear (deep trough over the eastern conus with 50+kts of shear) as it gets near the northern gulf. Staying in the BOC is the best chance of survival and maybe some development (questionable though) before hitting land likely MX.

We need clarification from wxman since I don't know where that post was, but the shear between this disturbance and the Gulf coast is dropping rapidly and will stay low to moderate until this comes ashore if it does go north. There is nothing anywhere near 50 knots of shear there now and nothing like that is expected there over the next few days. The max I see on shear forecast charts is 15 to 20 knots of moderate shear from the southwest but not until it is almost onshore, and each model run shows that dropping.

[Ntxw]

This was his post this morning.

I think 50% is quite generous. Thinking 20-30% at most. Just way too much shear now. Upper low to NW, upper high to SE. Not in a good position to develop. If it tracks north it runs into 50-60kt SW winds off the LA coast in 24-36 hrs. I think part of the moisture goes north, part west. Have to watch the part that goes west more, as it may be the only chance of development.

...having to hold Bones back from the mic now.

I checked the models including short term guidance and indeed he is correct. For the next 36 hours the trough is still digging and there is a wall of winds right along the coast. If it stays down there long enough, you could be right and shear backs off but until then there is plenty of it up there. BOC is much more favorable. If we were talking about a well developed system and created it's own environment, could be a different story but it's currently not.