Storm Lorenzo: October 3/4 2019 **Technical Discussion Only**

Jpmarn

Starting a new thread on what is a tropical Hurricane Lorenzo which is in the middle of the Atlantic Ocean south of the Azores. More details can be found in the Hurricane season Thread. I am giving Lorenzo it's own thread because at present models are bringing the Storm towards Ireland. Models at present are keeping out to sea with only minimal impact on Ireland at the moment. The latest model run are bringing the storm a bit closer to the west coast. If the storm in it’s extra tropical state should have a direct hit on Ireland it could generate wind gusts of over 160 Kmh. The storm is due nearest us next Thursday or Friday.

---

Mod Note:This thread is going to get very busy over the coming days and we would ask posters to adhere to the forum charter. Most importantly keep it civil and friendly. There will be no time for messing and it is imperative that the thread is not dragged off topic.

Gaoth Laidir

The rapid intensification this morning happened just as it was passing into an area of very low wind shear (5 knots), as seen in this sequence of images from 00Z, 06Z and 12Z (far right, east of 40W, south of 20N). It's since been passing into that area of slightly higher shear, and the SHIPS model has it up to 20-25 knots late tomorrow.

The latest forecast track has storm intensity around 90 knots at 18Z on the 1st, about 300 NM southwest of the Azores. Looks like a direct hit for them a few days later but most likely in a much-weakened state by then.

M.T. Cranium

Even with the weakening it would still be in the cat-2 range possibly, or higher end cat-1 when passing through the Azores. Latest GFS has its centre coming no closer to Ireland than 22 deg W and I would estimate peak gusts on west coast around 60-70 km/hr if the current maps verified. But there would likely be some large swells and surfers might be getting excited by the prospects of this outcome. Still plenty of time for this to veer off the predicted track though.

Gaoth Laidir

Two recon aircraft are due to leave Barbados for Lorenzo in a few hours.

REMARK: THE NOAA 43 P-3 AND THE NOAA 49 G-IV WILL FLY 9- AND
8-HR RESEARCH MISSIONS, RESPECTIVELY, INTO AND AROUND HURRICANE
LORENZO TOMORROW. BOTH WILL DEPART TBPB AT 27/1200Z.

JanuarySnowstor

Icon gives a direct hit with Ireland. Ecm much closer to us also than gfs

JanuarySnowstor

Actually ECM IS A DIRECT HIT ALSO! !

Jpmarn

Just looking at the gfs on neweather.tv. As Lorenzo approach our part of the Atlantic Ocean it is going to break up partially during its extra tropical transformation. It's energy is going to spawn some secondary storm depressions giving a relatively high risk of stormy weather over the next 2 weeks or so.

Villain

The ECMWF track has been moving it further East, last 5 runs here.

Davaeo09

Been living on Sherkin for the summer and planning on moving back to Kilkenny this coming week.

Had planned on 2 trips up and back to get all my stuff across on the ferry.
If those latest models come through i will be rethinking my plans incase of ferry cancelation

Graces7

Davaeo09 wrote: »

Been living on Sherkin for the summer and planning on moving back to Kilkenny this coming week.

Had planned on 2 trips up and back to get all my stuff across on the ferry.
If those latest models come through i will be rethinking my plans incase of ferry cancelation

Wise idea anyways as equinoctial gales cause havoc. I am well stocked here so whatever happens, no worries. Just got more supplies in .

west mayo offshore island

FutureGuy

How does this compare to the last hurricane that came our way.

It's nuts that we are even using the words "hurricane", "Ireland" and "again" in same sentences.

pauldry

I think this storm will miss to our West but in the days after id be concerned that it may drag up further distubances of heavy rain and strong winds.

However with a washout of August, wet September and wet start of October we must be due a dry month soon.

On graphs on Met Eireann rainfall seems to equalize itself over the course of the year

Gaoth Laidir

Just the usual disclaimer that this will not be a hurricane at our latitude, but may have hurricane-force winds.

The ECMWF ensembles show that slight shift eastwards in the 00Z run versus yesterday's 12Z. The majority still offshore but some creaping eastwards and also to Iberia. Still no real change in net intensity at our latitude.





This morning's SHIPS LGEM has it at around 70 knots on reaching the Azores, with shear at 42 knots and increasing at that stage.

Jpmarn

Looking at Met.ie Atlantic charts and it shows Lorenzo affecting southern counties in the early hours of next Friday morning. But it looks a bit weaker and would generate no more than Status Yellow warning winds according to the present chart.

Gaoth Laidir

Thar he blows

Villain

A thing of beauty!

PokeHerKing

Absolute Unit!

Graces7

Villain wrote: »

A thing of beauty!

Gives me the creeps and the heebie jeebies and I am not easily scared. shudders

octsol

What are the chances this storm will hit the south west of ireland

JCX BXC

octsol wrote: »

What are the chances this storm will hit the south west of ireland

Unknown.

Gaoth Laidir

Latest tracks and intensity. Intensity is fairly tightly clustered around a Cat 1 at T +120 hrs, which is around the time it reaches the Azores, but there is a few hours timing difference between the models.





The 12Z SHIPS LGEM has it at 63 knots at that stage and weakening, with 48 knots of shear, moving at 25 knots over SSTs of 21 °C.

Meteorite58

From the Met Office :

Hurricane Lorenzo is the strongest hurricane on record to exist this far east in the Atlantic (Category 4, 145 mph). Whilst it is set to weaken to some extent before reaching the Azores, hurricane force winds and heavy rain are likely for these mid-Atlantic Portuguese islands.


https://twitter.com/StuOstro/status/1177613170900385793?s=20





Tropical Tidbits

Oneiric 3

This might look a bit trippy but a good comparison between the 12z runs of yesterday and the 0z runs of this morning regarding forecast track of this storm from both the GFS and the ECMWF:

GFS: 12z (yesterday) vs 00z:





ECMWF 12z (yesterday) vs 00z:




All over the gaff, not only between the two models, but between different runs of the same model.

Gaoth Laidir

Comparison of ICON output for both Lorenzo and Ophelia. At the moment Ophelia is the big sister.

Lorenzo



Ophelia 2017

Kermit.de.frog

#prayforireland

Meteorite58

ECM 12Z rolling out and quite similar to the last run if bringing the remnants of Lorenzo a bit closer to the South of Ireland. Still the strongest winds offshore on this run .

Note showing 850 hPa winds below ( roughly a height of 1.5 km's )

Gaoth Laidir

A huge difference between the various models' pressure and wind analyses of Lorenzo at 12Z today. These are not forecasts, they're the actual initial starting conditions for the 12Z runs. The GFS is different to all the rest, but it may be closer to reality, as the microwave scans showed no real deep convection in that southwestern quadrant. The latest scan at 6 pm shows that the eyewall has actually dismantled further (bottom image, deep red colour) but a second one may be replacing it (to the south).

pauldry

Will definitely be a windy few days at the end of next week.

Too far away to determine whether it will be fierce but its interesting

Meteorite58

NHC mentons that Lorenzo has being passing over a slightly cooler surface temperature and is forecast to reach warmer water in 12- 24 hrs. After that, it stays over sea surface temperatures near 28C through about 72 h.

Mentions will be going through various eye wall replacement cycles.

NHC 'After 72 h,the cyclone will become embedded in the mid-latitude westerlies and
move over much colder water. This, and the approach of the
aforementioned deep-layer trough, will lead to extratropical
transition that will be underway, but likely not complete, by 120 h.'

UKM0 12Z +144 more to the SW/ W of Ireland on the latest run, filling on its approach.

Meteorite58

I think with the remnants of Lorenzo entering the fray next week and bringing up so much energy with it that it has the possibility of interacting with other areas of LP's as shown in the GFS 12Z and could be seeing quite an unsettled period around next weekend.

GFS not far off the UKMO and closer now to the ECM track than other runs but showing it stronger than the other models with a center pressure of around 930 hPa which is very much at odds with the ECM and UKMO.

Gaoth Laidir

This microwave scan just in shows that eyewall replacement cycle well underway. We might see a slight weakened intensity in the 10 pm discussion.

Gaoth Laidir

It's down to 110 knots in the latest update. Extratropical transition should be finished by T+120 h (at 44 N).

Hurricane Lorenzo Discussion Number 21
NWS National Hurricane Center Miami FL AL132019
500 PM AST Fri Sep 27 2019

The satellite appearance of Lorenzo has degraded further since the
last advisory, with only a hint of an eye still apparent in visible
imagery and the cold cloud tops in the eyewall becoming very
asymmetric in infrared imagery. A recent SSMI/S overpass shows
that the southern portion of the eyewall has eroded, possibly due to
shear or dry air intrusion. The microwave imagery also suggests an
outer convective band is forming, but it is not yet well enough
defined to call it an outer eyewall. Satellite intensity estimates
have continued to decrease, and the initial intensity is lowered to
110 kt as a blend of the various estimates. The hurricane continues
to have excellent outflow in the northern semicircle.

The initial motion remains 330/12 kt. There is no change in the
track forecast philosophy or the forecast confidence, as Lorenzo
should turn northward and then northeastward during the next few
days as it moves around the western edge of a mid-level ridge
centered over the eastern Atlantic. Later in the forecast period,
the cyclone is expected to accelerate northeastward in the
mid-latitude westerlies ahead of a deep-layer trough approaching
from the west. The track guidance for this advisory, while it
remains tightly clustered in direction, is a little slower than the
previous guidance. Based on this, the new forecast track is just a
little slower than the previous forecast.

Lorenzo will be passing over sea surface temperatures of 27-28C for
the next 48-72 h. However, it will be in an environment of moderate
vertical shear due to an upper-level trough not far to the west.
The intensity guidance responds to this by showing gradual
weakening during this time, and the new intensity forecast follows
the trend of the guidance. There is a possibility of fluctuations
in intensity caused by eyewall replacement cycles superimposed on
this weakening trend. After 72 h, the hurricane should encounter
stronger mid-latitude westerlies, move over cooler sea surface
temperatures, and eventually merge with the above-mentioned
deep-layer trough. As this occurs, Lorenzo is forecast to undergo
extratropical transition, with this being complete by 120 h.
Current indications from the global models are that Lorenzo will
retain hurricane strength through the transition.


FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 20.3N 43.6W 110 KT 125 MPH
12H 28/0600Z 21.6N 44.1W 105 KT 120 MPH
24H 28/1800Z 23.3N 44.3W 100 KT 115 MPH
36H 29/0600Z 25.0N 44.0W 100 KT 115 MPH
48H 29/1800Z 26.6N 43.3W 100 KT 115 MPH
72H 30/1800Z 30.3N 41.1W 95 KT 110 MPH
96H 01/1800Z 35.5N 36.0W 90 KT 105 MPH
120H 02/1800Z 44.0N 26.5W 80 KT 90 MPH...POST-TROP/EXTRATROP

hatrickpatrick

NHC now show it becoming extratropical further south of Ireland than Ophelia did, but it'll be interesting nonetheless since they show it only weakening to just below Cat 2 strength by that time, so it could still potentially cross Ireland with stronger winds than Ophelia did depending on how it tracks. ECM shows it crossing the south of the country, while the UKMO cuts off just before showing that timeframe but seems to be following the ECM up until then. Going to be a very interesting few days, particularly to see how Met Eireann reports this after all the (completely bullsh!t in my view) criticism they got for "overhyping" the red weather alerts of 2017 and '18.

igCorcaigh

hatrickpatrick wrote: »

NHC now show it becoming extratropical further south of Ireland than Ophelia did, but it'll be interesting nonetheless since they show it only weakening to just below Cat 2 strength by that time, so it could still potentially cross Ireland with stronger winds than Ophelia did depending on how it tracks. ECM shows it crossing the south of the country, while the UKMO cuts off just before showing that timeframe but seems to be following the ECM up until then. Going to be a very interesting few days, particularly to see how Met Eireann reports this after all the (completely bullsh!t in my view) criticism they got for "overhyping" the red weather alerts of 2017 and '18.

Totally agree with that last comment.

Anyway, if this approaches anything Ophelia like, people need to be aware.

The fact that this system is the most powerful this far East makes it stand out anyway.

Interesting times!

Kermit.de.frog

One or two interesting evolutions starting to appear for us.




Johanna Donnelly will have her Ophelia face on in a few days I reckon. :P

Oneiric 3

That UKMO chart posted above looks scarily Debbyesque. Different times and different methods of course, but forecasters at the time predicted that the worst of that particular storm would stay off well to the the west of Ireland. (I posted the Irish Times chart and forecast for that fateful day years back, but wound't have a hope of finding it now)

Hooter23

"This is Happening" :pac:

SleetAndSnow

Navgem though, generally very unreliable if I remember correctly right? Regardless I’d trust the ecm most here with us possibly feeling 70kmph winds along the SW/W coasts vs a southerly direct hit

Harry Palmr

The jet stream is pretty volatile right now, it could push this wind away as much as it could steer it over us.

Kermit.de.frog

Yeah this needs watching

Gaoth Laidir

What happens Lorenzo after the Azores depends on how an upper trough coming off eastern Canada interacts with. The 12Z ECM has the trough not absorbing the low-level centre but giving it a shot in the arm as it continues towards us. By Thursday evening the low reaches the southwest coast with around 50-knot mean winds at 100 metres, around 40 knots on the surface, highest offshore.

Oneiric 3

This is what we are dealing with... and this is just one model run.. of many.

Gaoth Laidir

Oneiric 3 wrote: »

This is what we are dealing with... and this is just one model run.. of many.

Meteorite58

GFS 18Z has thrown in a direct hit on the latest run. My trees !

Still about 132 hrs out so very much in the unreliable timeframe but certainly starting to see charts showing it tracking close to our shores.

Has a pressure of 960 hPa this time, +30 hPa on the last run.

Oneiric 3

Slightly tidier looking. EPS mean (850 hPa ws > 50 knots for time in question)


for the second run in a row now, the ECMWF op has broken free from the general consensus. Either it is onto something (it is the highest res of all the runs afterall) or it is just being mischievous.

Kermit.de.frog

https://www.youtube.com/watch?v=rpFfXWr_gRo

sdanseo

Even a 960mb low with extratropical features and 40kt sustained wind is no joke.

Note: from here on, post is borderline hyperbole based on ONE run. But still worth talking about.

GFS on the other hand. Literally off the scale with >160km/h gusts over land. I've never seen this on a GFS chart before, it's stuff usually reserved for ICON, or NAVGEM when it's had a few pints.

Edit: Portions of coastal Kerry could see 130km/h +mean wind here. Well into sustained hurricane force. (2nd pic)

ICON comes into range tomorrow night, could make for some spectacular (if speculative) charts with quite a lot of black off-the-chart type windspeeds in them.

Gaoth Laidir

12Z ECM ensembles. Look similar to the previous couple of runs?

igCorcaigh

Well wouldn't that be something.
Hopefully not though, as much as I love a good storm.

pauldry

Remember all charts look fantastical at night runs but by morning watch for the "and now its gone" comments before it reappears as a yellow warning next weekend

uck51js9zml2yt

I read the first post and my first thought was would you "feck off" with your hurricanes

I'm in the south west on the side of a mountain facing the Atlantic.

I nice shower would do grand and a bit of a breeze

How come Harm what's his name didn't mention hurricanes in his report on rte radio at 6 this evening?