Major Hurricane Delta

[dan11295]

Intensity guidance (yeah I know it hasn't done particularly good with Delta) brings it to 100-105kt before it starts to weaken prior to ~90 kt landfall. I still think 85-95 kt will be final landfall intensity. regardless of how much it strengthens in the short term. Large wind field will be a surge problem and puts Lafayette a bit under the gun as far as wind, although they are inland a bit with a weakening storm to mitigate the effects some. Regardless, Louisiana is still dealing with effects of Laura and they certainly don't need another storm.

[hawkeye_wx]

973 mb per the latest dropsonde.

[Prospero]

10 minutes ago, Moderately Unstable said:

Sock puppet eh. What show do I star in? I can't wait for my reviews! Based on the last couple of days, RI may be relative. What was seen a couple of days ago was voracious and unusual. We should, based on the recent imagery coming in, expect I. The guidance says we should see more intensity, the microwave and IR imagery is improving, the above post referenced by Windspeed and JasonOH was in particular an "oh, well then", moment. I am taking the same approach as the NHC likely is about to right now, in not jumping the gun and rapidly changing their thinking. Hours back, folks were saying, it may be a 1! What a joke! etc. We can't swing 1-4-1-ts-4-5!. I still think a cat 3 peak is the most likely scenario. Big cat 3, maybe upper end cat 3, with extensive surge impact. But right now I go mid cat 3. Outflow does look a lot better, and historical context suggests good outflow is key in terms of sustaining and maintaining a clean core, which appears, again above, to be developing. To the two earlier posters who said the nice things welcomed me--thank you :). It is nice to have a place to discuss weather without being looked as though I have three heads. 

 

MU/CD

Beware the ghost of leroy!

A high-end experienced troll who may very well be paid a lot of money to add fire to this forum (and how knows how many more, and a possible professional troll)!

Not an idiot, which makes him more effective.

But a sh*t stirrer by trade, and good at it. LOL

Welcome to this forum!

[Windspeed]

Beware the ghost of leroy!

A high-end experienced troll who may very well be paid a lot of money to add fire to this forum (and how knows how many more, and a possible professional troll)!

Not an idiot, which makes him more effective.
But a sh*t stirrer by trade, and good at it. LOL
Welcome to this forum!

Really? That dude is salivating for GOM Cat 5 more than anyone here. The reality is it will just become a formidable major hurricane again. Not wishcasting, just based on environmental influences here. This is really just dumb. GOL is a good poster.

[Doc Jon]

who was it talking about a notch in the core overcast symmetry being a sign of RI back on the Laura thread?  I ask because one just showed up in the last few frames.

[Prospero]

3 minutes ago, Windspeed said:

11 minutes ago, Prospero said:

Beware the ghost of leroy!

A high-end experienced troll who may very well be paid a lot of money to add fire to this forum (and how knows how many more, and a possible professional troll)!

Not an idiot, which makes him more effective.
But a sh*t stirrer by trade, and good at it. LOL
Welcome to this forum!

Really? That dude is salivating for GOM Cat 5 more than anyone here. The reality is it will just become a formidable major hurricane again. Not wishcasting, just based on environmental influences here. This is really just dumb. GOL is a good poster.

I thought "ghost..." was trolling new poster Moderately Unstable who has good posts. He's better than me who is a poor poster yet with passion.
But me being new, this season I think (times so flies), "ghost of leroy" pops up a bit and I've been trolled.
 

Of course we all want Cat 5 storms every spin, but that is our nature but we cannot really say that. We really DO care about lives and costs.

But really, secretly in our minds we all want the biggest storm ever on every spin. Just who we are.

[hawkeye_wx]

Pressure is still 973 or 974 mb.  The eye is 30 nm wide.

[Windspeed]

Pressure is still 973 or 974 mb.  The eye is 30 nm wide.

I don't really see any rapid deepening until tomorrow afternoon when the large core is over the best heat content and best upper tropospheric dynamics.

[JasonOH]

From VDM:

F. CLOSED
G. C30

TLDR: Eye is closed. 30nm diameter

[the ghost of leroy]

3 minutes ago, JasonOH said:

From VDM:

F. CLOSED
G. C30

TLDR: Eye is closed. 30nm diameter

Nice. 

[hlcater]

 

Honestly has a better convective pattern than yesterday lol.

[Amped]

1 minute ago, hlcater said:

 

Honestly has a better convective pattern than yesterday lol.

More of an eye too.

[jojo762]

Tomorrow is probably gonna be a fun day, anticipate rapid re-intensification... Outflow and cloud/convective patterns have greatly improved with Delta today... Latest IR imagery is pretty telling that it’s about to take off as we have intense convection starting to wrap around the COC.

[Doc Jon]

got lightning popping off in the core.

[tiger_deF]

Raw ADT of 7.3

[olafminesaw]

Down to about 970/71 mb

[Moderately Unstable]

Combined, the latest vdm message and current sat imagery make a compelling case that the eye is clearing out, banding has increased, and the storm is looking healthier...all point towards steady--not rapid but not nothing--intensification and with hints of a clear eye now showing on the simulated visible satellite we will probably be back at Cat 2 on the 11pm update. It should be noted that the 00z intensity guidance has been released and almost all of the models show a cat 2 peak now, even the often bullish ships. I don't totally buy that because of the underlying ocean temps and overall setup, and the frank fact that this storm doesn't need all that much to get to cat 3 strength--organizationally speaking. But the earlier post I wrote coupled with the current imagery continues to lead me to a mid grade cat 3 solution. That's not exactly GOOD news for the areas to be affected by this thing, largely the same ones still recovering from Laura. This is like having a baseball hit you when you're already opened up for surgery. Ouch. 

 

I want to quickly note that in mature steady state, strong tropical systems, we don't see a ton of lightning around the eye. That indicates one of a few things. One is and EWRC. That ain't happening here. Two is very vigorous convection--which usually correlates with a strengthening cyclone but not always. We DO have that here and that is the cause of the lightning. The same way you get lightning in your garden tstorms (side bar, hurricanes are basically a conglomeration of garden variety tstorms that basically synergistically combine to create the pressure falls and structure that become a hurricane--"garden variety" tstorms form in barotropic environments), you get in tropical systems. That is--high cloud tops, vigorous updrafts, and charge separation of the resultant cloud droplets with height. But hurricanes are wind storms. Lightning tells us about the updraft strength, not how much energy is focusing into cyclostrophic balance in the RMI. They are correlated, they are not synonymous. What has me going "ah this is probably a cat 2 again" is the symmetry I'm seeing of the eye itself now, and the fact the hunters found a closed eye. That is important in creating inertial stability and reduces the impact of short temporal scale extrinsic storm influences. 

 

On the latest T#, it is not 7.3. That is the raw number, and as the system noted, it estimates a 10 km pinwheel eye. That is incongruent with aircraft in situ measurements stating a 30 nm closed eye. The adjusted T number given is 5.0, meaning a mid range cat 2 storm, using one particular computer algorithms estimating technique. A T 7.3 corresponds to cat 5 winds. This ain't that. I buy T 5.0.  

 

MU

[JasonOH]

It's back to open SW on latest VDM.

[BuffaloWeather]

Looks like its getting more organized tonight.

[Radtechwxman]

NHC hitting the weakening pretty hard prior to landfall. Based on it's organization tonight, I think it could overachieve current intensity forecasts

[yoda]

BULLETIN
Hurricane Delta Advisory Number  14...Corrected
NWS National Hurricane Center Miami FL       AL262020
1000 PM CDT Wed Oct 07 2020

Corrected to remove Mobile Bay from the Storm Surge Warning area

...STORM SURGE AND HURRICANE WARNINGS ISSUED FOR A PORTION OF THE
NORTHERN GULF COAST...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...22.5N 90.9W
ABOUT 525 MI...845 KM SSE OF CAMERON LOUISIANA
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...972 MB...28.71 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

A Storm Surge Warning has been issued from Sabine Pass to Ocean
Springs, Mississippi, including Calcasieu Lake, Vermilion Bay, Lake
Pontchartrain, Lake Maurepas, and Lake Borgne.

A Hurricane Warning has been issued for the northern Gulf of Mexico
coast from east of Sabine Pass to Morgan City, Louisiana.

A Tropical Storm Warning has also been issued for the northern Gulf
of Mexico coast from San Luis Pass, Texas to Sabine Pass, and east
of Morgan City, Louisiana to the mouth of the Pearl River,
including New Orleans, Lake Pontchartrain and Lake Maurepas.

The Storm Surge Watch has been discontinued from the
Mississippi/Alabama border to the Alabama/Florida border, including
Mobile Bay.

The government of Mexico has discontinued the Tropical Storm
Warning from Rio Lagartos to Dzilam, Mexico.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* Sabine Pass to Ocean Springs, Mississippi including Calcasieu
Lake, Vermilion Bay, Lake Pontchartrain, Lake Maurepas, and Lake 
Borgne

A Storm Surge Watch is in effect for...
* High Island, TX to Sabine Pass
* East of Ocean Springs, Mississippi to the Mississippi/Alabama
border

A Hurricane Warning is in effect for...
* East of Sabine Pass to Morgan City, Louisiana

A Tropical Storm Warning is in effect for...
* San Luis Pass, Texas to Sabine Pass
* East of Morgan City, Louisiana to the mouth of the Pearl River,
including New Orleans
* Lake Pontchartrain and Lake Maurepas

A Tropical Storm Watch is in effect for...
* East of the mouth of the Pearl River to Bay St. Louis Mississippi

[yoda]

Hurricane Delta Discussion Number  14
NWS National Hurricane Center Miami FL       AL262020
1000 PM CDT Wed Oct 07 2020

Observations from an Air Force Reserve Unit Hurricane Hunter
aircraft indicate that Delta is gradually strengthening while it
moves over the open waters of the south-central Gulf of Mexico.
Based on a blend of adjusted flight-level and SFMR wind
measurements from the plane, the current intensity is set at 80 kt.
The cloud pattern of the hurricane continues to become better
organized on satellite images, with a growing Central Dense
Overcast, and convective banding features becoming better defined,
particularly over the northern semicircle of the circulation.
Additional intensification is likely while Delta moves through a
favorable environment during the next day or so, and the official
forecast is fairly close to the corrected consensus guidance, HCCA.
When the system moves into the northern Gulf, a decrease in oceanic
heat content, drier mid-tropospheric air, and increased vertical
shear should cause at least slow weakening.  The NHC intensity
forecast is above the numerical guidance in 36-48 hours.  It should
be noted that 1-2 day tropical cyclone intensity forecasts are
subject to errors of around 1 Saffir-Simpson category.

The global models show a further increase in the size of the
hurricane while it moves into the northern Gulf.  The official wind
radii forecasts are based on a consensus of these model predictions.

The latest center fixes from the Hurricane Hunters show a
west-northwestward motion, at about 300/15 kt.  Delta should turn
toward the north-northwest and north over the next 36 hours or so
while moving around the western periphery of a subtropical high
pressure system centered over Florida.  When the hurricane moves
into the northern Gulf of Mexico on Friday, Delta should turn
toward the north-northeast on the southeastern side of a
mid-tropospheric shortwave over the southern United States.  The
official track forecast is close to both the simple and corrected
dynamical model consensus predictions, TVCA and HCCA, respectively.
These objective aids are in close agreement with one another.

Based on the official forecast, it is time to issue storm surge and
hurricane warnings for a portion of the northern Gulf of Mexico
coast.


Key Messages:

1. Delta is expected to grow in size as it approaches the northern
Gulf Coast, where life-threatening storm surge and dangerous
hurricane-force winds are likely beginning Friday, particularly for
portions of the Louisiana coast.  Storm Surge and Hurricane Warnings
are in effect, and residents in these areas should follow advice
given by local officials and rush preparedness actions to
completion.

2. Flash, urban, small stream and minor to isolated moderate river
flooding is likely Friday and Saturday from portions of the central
Gulf Coast into portions of the Lower to Middle Mississippi Valley.
As Delta moves farther inland, additional heavy rainfall is expected
in the Ohio Valley and Mid Atlantic this weekend.


FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 22.5N  90.9W   80 KT  90 MPH
 12H  08/1200Z 23.7N  92.2W   95 KT 110 MPH
 24H  09/0000Z 25.4N  93.4W  105 KT 120 MPH
 36H  09/1200Z 27.5N  93.5W  100 KT 115 MPH
 48H  10/0000Z 30.0N  92.7W   85 KT 100 MPH
 60H  10/1200Z 32.4N  91.5W   35 KT  40 MPH...INLAND
 72H  11/0000Z 34.2N  89.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  12/0000Z 37.5N  85.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  13/0000Z...DISSIPATED

[Moderately Unstable]

11 minutes ago, StormChaser4Life said:

NHC hitting the weakening pretty hard prior to landfall. Based on it's organization tonight, I think it could overachieve current intensity forecasts

As we have already seen, with this storm directly in fact, what happens tonight has very little to do with what happens in 2 days. The nhc weakens the storm near landfall for sound meteorological reasons: the water is cold near the coast, shear increases near the coast, and perhaps dry air tries to entrain the circulation near the coast. If ALL THREE of those things hit at maximal extent, it doesn't take a PhD to recognize significant weakening would occur. Storms can rapidly intensify, AND as we saw, rapidly weaken. Ergo, don't fall into the forecasting trap of seeing something happening now and assume that it must be true later too! *If the storm is stronger at landfall, it will be due to a high rate of forward speed and having limited time for these objectively bad for the storm things to impact it*. Cold water weakens hurricanes. So does shear. So does dry air. *There is no physical mechanism near the coast that is expected to be favorable for hurricane maintenance and strength*. The degree of unfavorability and landfall intensity will come down to shear and any dry air entrainment. We know the water is marginal. If no shear or light shear is present, it will exceed the forecast intensity at landfall. If shear is moderate, or the inner circulation entrains dry air, the storm will weaken about to the degree the nhc is noting.

Yesterday, we had warm ssts and modest shear and bam, cat 4 drops to cat 2 on a dime. That was in a supposedly pristine environment. Right now we are continuing to see steady strengthening. That's what we can say objectively. Not how that affects landfall. If the storm were 12 hours from landfall and strengthening, different story.

 

MU/CD

[Yeoman]

Any hot towers?

[nycwinter]

17 minutes ago, Moderately Unstable said:

As we have already seen, with this storm directly in fact, what happens tonight has very little to do with what happens in 2 days. The nhc weakens the storm near landfall for sound meteorological reasons: the water is cold near the coast, shear increases near the coast, and perhaps dry air tries to entrain the circulation near the coast. If ALL THREE of those things hit at maximal extent, it doesn't take a PhD to recognize significant weakening would occur. Storms can rapidly intensify, AND as we saw, rapidly weaken. Ergo, don't fall into the forecasting trap of seeing something happening now and assume that it must be true later too! *If the storm is stronger at landfall, it will be due to a high rate of forward speed and having limited time for these objectively bad for the storm things to impact it*. Cold water weakens hurricanes. So does shear. So does dry air. *There is no physical mechanism near the coast that is expected to be favorable for hurricane maintenance and strength*. The degree of unfavorability and landfall intensity will come down to shear and any dry air entrainment. We know the water is marginal. If no shear or light shear is present, it will exceed the forecast intensity at landfall. If shear is moderate, or the inner circulation entrains dry air, the storm will weaken about to the degree the nhc is noting.

Yesterday, we had warm ssts and modest shear and bam, cat 4 drops to cat 2 on a dime. That was in a supposedly pristine environment. Right now we are continuing to see steady strengthening. That's what we can say objectively. Not how that affects landfall. If the storm were 12 hours from landfall and strengthening, different story.

 

MU/CD

well the shear weakened the storm considerably so the environment was not pristine..

[Radtechwxman]

15 minutes ago, Moderately Unstable said:

As we have already seen, with this storm directly in fact, what happens tonight has very little to do with what happens in 2 days. The nhc weakens the storm near landfall for sound meteorological reasons: the water is cold near the coast, shear increases near the coast, and perhaps dry air tries to entrain the circulation near the coast. If ALL THREE of those things hit at maximal extent, it doesn't take a PhD to recognize significant weakening would occur. Storms can rapidly intensify, AND as we saw, rapidly weaken. Ergo, don't fall into the forecasting trap of seeing something happening now and assume that it must be true later too! *If the storm is stronger at landfall, it will be due to a high rate of forward speed and having limited time for these objectively bad for the storm things to impact it*. Cold water weakens hurricanes. So does shear. So does dry air. *There is no physical mechanism near the coast that is expected to be favorable for hurricane maintenance and strength*. The degree of unfavorability and landfall intensity will come down to shear and any dry air entrainment. We know the water is marginal. If no shear or light shear is present, it will exceed the forecast intensity at landfall. If shear is moderate, or the inner circulation entrains dry air, the storm will weaken about to the degree the nhc is noting.

Yesterday, we had warm ssts and modest shear and bam, cat 4 drops to cat 2 on a dime. That was in a supposedly pristine environment. Right now we are continuing to see steady strengthening. That's what we can say objectively. Not how that affects landfall. If the storm were 12 hours from landfall and strengthening, different story.

 

MU/CD

I have a degree in meteorology. I understand man. I'm talking about it getting stronger the next day or so in the more favorable conditions. If you end up with a stronger storm in the short term, you will likely have it landfall stronger. Yes it has plenty working against it as it nears landfall but a well formed core of a strong hurricane just won't instantly degrade. Yes there will be weakening but with a larger circulation developing as were already seeing. That won't break down as fast as Delta did prior to landfall in Yucatan when the circulation was much smaller. It all depends on what happens while the environment is ripe for intensification 

[StormchaserChuck!]

ERC.

[JasonOH]

6 minutes ago, StormchaserChuck! said:

ERC.

I don’t think it’s an ERC since the eyewall never really has been stable yet. I think it’s more due to the fact that there isn’t a super strong eyewall so the wind max isn’t as concentrated.

[StormchaserChuck!]

yes, what an impressive storm. 

Edit: I can't see below Cat 4 at land fall, not enough space. 

[Moderately Unstable]

9 minutes ago, StormChaser4Life said:

I have a degree in meteorology. I understand man. I'm talking about it getting stronger the next day or so in the more favorable conditions. If you end up with a stronger storm in the short term, you will likely have it landfall stronger. Yes it has plenty working against it as it nears landfall but a well formed core of a strong hurricane just won't instantly degrade. Yes there will be weakening but with a larger circulation developing as were already seeing. That won't break down as fast as Delta did prior to landfall in Yucatan when the circulation was much smaller. It all depends on what happens while the environment is ripe for intensification 

I do as well. I agree with your principle--you are right, all things equal, you have a stronger initial intensity, your final intensity for a given time B is higher. But all things are not equal. We had a well formed core of a strong hurricane wilt away under moderate shear when a quasi linear convective band dessicrated the pinhole eye. Working in favor of slower lowering of intensity is a projected increase in the diameter of the eye, and larger size of the storm, which should lend a degree of stability and buffer it against some of these deleterious things. I don't disagree with your supposition that the storm gets stronger in the next 24-36 hours. Everyone agrees there. This is more a question of, let's say we have a 130mph cat 4 (being very generous here)...that is still going to weaken substantially in the 8 hours it has to traverse the suboptimal conditions. 100-110 landfall is reasonable with a 130 mph storm, and again that would be stronger than it is projected to get. We have so many analogues and examples to go off of to further that point. It isn't like the conditions are going to deteriorate with 3 hours to go before landfall. We are talking 6-12 hours. That's a lot of time for change for a hurricane. 

12 minutes ago, nycwinter said:

well the shear weakened the storm considerably so the environment was not pristine..

You're right. I should have said forecasted to be pristine. But, that is somewhat the point I was getting at. Gangbusters ssts and moist air but some shear and goodbye organized eye.