jpeters3

Meteorologist
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Posts posted by jpeters3


  1. 2 minutes ago, OSUmetstud said:

    Its 10mb lower than the other plane though. Somethings wrong there. 

    It's just simple formula - doesn't mean there is "something wrong with the plane" 

    Also, planes are flying at different altitudes, which probably explains the different extrapolations. 

    • Like 1

  2. 1 minute ago, tiger_deF said:

    That plane has been having extrap issues all day so the sonde will be crucial

    I don't think it's the plane per se, it's probably that the traditional reduction formula isn't very accurate in this situation.

    • Like 1

  3. Just now, vortex95 said:

    I wasn't throwing in the towel and I was not being irresponsible.  Laura is a significant threat.  Just pointing caveats on its intensity potential.   And I did acknowledge there is a transition time by using the words "gradually" and "with time"

    "You want to see a smooth ring of convection gradually develop, and cool with time, and wrap around the center,
    and most importantly, persist for more than just a couple of hours."

    NHC points out the caveats in terms of dry air and shear well in the 4pm CDT discussion.  They say dry air could still be a factor but don't go with it explicitly for now.  Shear will be a factor 6-12 hr before landfall, so it is prudent to not go too aggressive in the intensity at this point.  They did not change their intensity forecast at landfall from 10am CDT.
     

    Got it.  Apologize for my critical post.

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  4. 12 minutes ago, vortex95 said:

    Rapid very cloud top convective development in a blob fashion in one quad isn't generally a good sign overall for significant intensification. You want to see a smooth ring of convection gradually develop, and cool with time, and wrap around the center, and most importantly, persist for more than just a couple of hours.   At that point, RI is much more likely.

    This logic is flawed.  You seem to state that you need good organization to get good organization.  But what you are failing to acknowledge is that there is a transitional time period between bad organization and good organization.

    Not saying that RI is imminent or even that it will definitively happen, but just that it is irresponsible to throw in the towel based on ill-concieved notions.


  5. 1 minute ago, HKY_WX said:

    I disagree w/ your premise that you cant have a Cat 3 or 4 with some mid-level dry air around. It's happened many times. Almost all major hurricanes that track north of 25 Latitude will likely face dry air problems. If we're talking about achieving  Cat 5/historical wind/pressures, sure I would agree the environment would need to be pristine.

    You're hard pressed to find large scale anticyclone with very high RH in the middle troposphere within it... And large scale anticyclones are favorable regions for TC intensification.

    • Like 1

  6. Just now, Dunkman said:

    I was going to ask about the comma shape. It seems when storm gain that shape on the east coast they're never able to revert back to a symmetrical look even when conditions greatly improve. I assume that isn't usually the case in the gulf?

    I suspect the comma shape was due to northerly shear.  It's possible that this will go away as the shear abates. 


  7. Just now, TradeWinds said:

    Honestly bombs away and RI are too overused. Not every tower firing means RI. Would be a good drinking game for sure on this board. 

    Every hot tower = RI, and every minor warming of the cloud tops or slight degradation of the satellite presentation = weakening.

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  8. Just now, vortex95 said:

    There are three key things that have to be ideal for an intense hurricane: 1) warm enough SSTs, 2) low shear, and 3) a moist column.  If any one of these three is not ideal, it is difficult to get anything higher than a strong Cat 2 IMHO.  Occasional dry air intrusions are going to likely be persistent issue up until landfall for Laura. And just the elongated structure N-S that has persisted, that isn't a overall good sign for significant intensification anytime soon.  Latest EIR loop show irregular strong bursts of very cold IR tops in the S quad of the circulation.  These irregular bursts have been an issue for days now.  Is there any real reason to expect they will stop since mid-level RH will remain a bit too low (60% or less)?
     

    We've discussed the RH issue a bit.  I don't think this will be a huge hinderance to strengthening so long as shear is low.  Dynamically, the pulse-like nature is more connected to shear than to RH.  Now, when shear is present, low RH probably has a more deleterious effect than high RH.  But it does look like the system is trying to get its act together, in a way that It hasn't throughout the entirety of its life up to this point.  For instance, the new pulses of convection are forming a concentric ring.


  9. 2 minutes ago, Hotair said:

    Given the lightning flashes on the SW side do we still think this is not a sign that the clearing in satellite imaging is due to beginning of eye formation and its just a dry air patch ?  When or how can we tell for certain? 

    Wait and see if it turns into an eye.  ;)


  10. 1 minute ago, jbenedet said:

    We are splitting hairs here honestly. Every loop I see shows a system that is organizing. And more recently the organization appears faster than earlier in the day....

    While we are splitting hairs, it looks like the northward outflow is becoming less restricted, with CDO starting to blow off in that direction.  So maybe the shear has wained. 

    • Like 3

  11. 6 minutes ago, jbenedet said:

    :facepalm:

     

    Didn’t we *just* go through this with Isaias ad nauseum? 

    He’s wrapping up and gaining symmetry. Let’s not overthink this....He’s a cat 1 for a reason. Cat 1’s are never aesthetically appealing...that’s why they’re cat 1’s...

    Also, shouldn't you be saying "she"??? :P

    • Haha 6

  12. 4 minutes ago, OSUmetstud said:

    Yeah I think thats an eye too. 

    Turns out the air is dry in the eye.  Who would have thought...

    There is a little bit too much obsession with dry air in here, IMO.  It really takes shear to get dry air into the core of TCs, so it all points back to shear being the main hinderance.  And I think there was clear evidence (at least earlier today) of some northerly shear.  If shear does indeed drop below 5 kts, and if there is a closed eyewall by that point, I doubt dry air will have much of an effect on intensification.  

    • Like 5
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  13. 4 minutes ago, StormChaser4Life said:

    Crazy how much dry air has plagued systems this year. NHC has been saying a very moist environment but there's definitely some drier air in the western Gulf. Curious if this will keep Laura in check. Some dry air definitely hindering convection on western side

    I think shear is the real culprit here.  It shows up in the analysis, and in the visible loop as cirrus anvils being blown southward of convective cores to the north of the CDO. 

    • Like 2

  14. 5 minutes ago, Superstorm93 said:

    Very interesting. What's the data source for those plots? Obviously the UWISC shear plots have <5 knots of shear...

    This is from Colorado state's / CIRA site.  Makes sense given the satellite appearance.

     

    https://rammb-data.cira.colostate.edu/tc_realtime/storm.asp?storm_identifier=al132020

    Here is the description of the product 

    AMSU Area-Averaged Wind Shears and Layer Means

    These products use the balanced 3-D wind field derived from the AMSU temperature retrievals to estimate the area averaged vertical wind shear and mass weighted deep-layer mean wind in two layers (200 to 850hPa and 500 to 850Hpa). For these calculations the area averaging is calculated in the area contained within 0 to 600km from the center of the cyclone. These are displayed for each AMSU retrieval time available. These may be useful for detecting rapid changes in the synoptic wind field. The reliability of the vertical wind shear estimates is documented in Zehr et al. (2008).

    • Thanks 1

  15. Just now, vwgrrc said:

    Did the track shift back East? I thought morning guidance show it's aiming Houston/Galveston area.

     

    4 minutes ago, bdgwx said:

    Even COAMPS, which had been stubbornly muted on intensification, is now predicting a 937mb cat 4 cyclone prior to landfall.

    lSWGtBv.gif

    Gotta love how COAMPS only gets brought up here when it shows a favorable solution ;-)

    • Like 1

  16. 18 minutes ago, the ghost of leroy said:

    Watch out, you’re going to get lectured about how there have been cat 5’s near 930 before

    I suppose I made the wrong point.  In the past, it seems like you need <920 hPa to get cat 5 winds in the gulf (though the sample size is pretty small).  But my point was the level of disorganization up to this point in the storm's life has absolutely no bearing on what pressure is needed to achieve cat 5 winds.

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  17. 1 minute ago, the ghost of leroy said:

     

    The thing that has been sloppy and loose its entire existence isn’t going to be a a cat 5 unless it makes it <910. 931 ain’t gonna cut it. 

    This doesn't really make sense.  There have been several cat5 storms with pressure in the vicinity of 930 hPa.  I don't get how "sloppy and loose" has anything to do with the pressure needed to achieve cat 5 winds.  Obviously if it approaches cat 5, it won't be "sloppy and loose" anymore.

    Not saying that I think cat5 is likely.  It is *possible,* but not the most probable outcome.

    • Like 5

  18. 2 minutes ago, brentrich said:

    Anyone thinks Laura has a chance to become Cat 5 hurricane before landfall? 

    You're probably best just rolling the dice on this one.  It is certainly *possible,* but probably not the most likely outcome. 

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