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

M.T. Cranium

Looking at the satellite loop for past six hours, there was some sign of an eastward wobble in the past two hours, so might look for any sign of that trend on 18z run guidance. Would imply a closer trajectory to Connacht and possible elimination of the Donegal landfall option.

Without data of course it's not easy to assess small-scale changes. The ocean buoy that used to report from 49N 16W (PAP) seems to be out of service too.

M6 buoy will give us valuable data after midnight. Steady SSE wind around 35-40 km/hr there all afternoon and evening so far.

mickger844posts

Mod Note: Lets keep the chat to its own thread and keep this "Technical" please.

m17

The azores 02/10/19

m17

The azores 02/10/19

Gaoth Laidir

DOCARCH wrote: »

Total ramper!!! His reports today have pi**ed me off.

Arguably we have never had a hurricane come in over us and it's not happening tomorrow or Friday either!

Both he and that guy who presents Six One (Ray something) are clueless. Today he said that Lorenzo had washed a turtle up.om a beach...and it still about 1500 km away at the time. Yesterday he said we'd be getting a tropical storm. Clueless.

Anyway, this was the windfield at 18Z. And zoomed in.





85 GHz microwave. No structure left.

pad199207

Some convection building again. Definitely an eye wall forming ;-)

typhoony

a small downgrade on GFS 18z

m17

Meteorite58

GFS 18Z showing it windy on the coasts but nothing exceptional, current charts has it barely reaching gusts of a 100km/h on the coast and perhaps 70 or 80 km/h gust inland but not penetrating far inland.

Mount Vesuvius

Latest Fax from UKMO
Serious storm surge and driving towards the west coast, high tides will be a menace. Get ready west coast.

Meteorite58

ICON has been taking a much further Northern track and filling off the N , hence no strong winds of note in over Ireland apart from being windy along coasts and a bit stronger on W/ NW coasts.

Meteorite58

ARPEGE 18Z rolling out and aligning more towards the ECM / EURO 4 / Hirlam . The center , after tracking up along the Western coast turns in towards Donegal Bay much quicker and more South than earlier runs. After turning inland tracks in a SE'ly direction, moving quickly overland.

Still a tad off the ECM and Euro 4' s max wind speeds but close .

Getting more in line with the forecasts.

pad199207

Could be some very strong winds affecting rush hour in Greater Dublin first thing Friday morning

m17

A big thanks to everyone for all the updates and charts let's keep it going and let's all stay safe out there

Meteorite58

pad199207 wrote: »

Could be some very strong winds affecting rush hour in Greater Dublin first thing Friday morning

Yes and with any system of this size and nature would need to expect the unexpected. The models can only predict so much. Still could track a bit closer to land and move in a bit quicker which would increase it's wind speeds I would imagine.

Galway looks like getting the brunt of it all right, people will need to assess the situation in the morning if safe to go out early, should have eased off considerably there by mid morning. Could be a fair few trees and lines down.

c.p.w.g.w

What time is landfall estimated for?

sdanseo

c.p.w.g.w wrote: »

What time is landfall estimated for?

Overnight Thursday to Friday - but the way the forecasts are going you might do well to notice unless you're on an exposed western coast.

Graces7

Already a strong wind out here. Out briefly and buffeted. West Mayo offshore island

octsol

Same here north Kerry.

M.T. Cranium

Sharp pressure fall in past hour at M6, wind only increased slightly (has been SE 50 km/hr gusting to about 80-85 past three hours).

https://www.met.ie/forecasts/marine-inland-lakes/buoys

Checked into the status of PAP buoy which would be quite close to current location of Lorenzo, unfortunately it has been down for some time.

Further east the K1 buoy has been reporting sustained SSE winds over 30 knots at quite a distance from the low and K2 (southwest of M3) has sustained 37 knots from southeast. Last available position of low (0430z) was near 52N 18W and around 966 mbs.

00z models seem to be converging on a rather slow turn to a Donegal Bay landfall around 03z Friday. Winds are likely to peak mid-afternoon on the west coast then back off, perhaps returning somewhat as the ever-weakening core of the decaying cyclone drifts to shore. Unless this fools the models and makes a faster right turn, it may turn into a general minor to non-event outside of coastal sea state impacts, possibly some locally heavy rains in west Ulster and north Connacht. Some local stream flooding in Donegal might occur with 30-40 mm amounts shown for Thursday night and Friday.

But the possibility of that faster right turn has to be respected. That is basically what happened with the Charley that hit Florida in 2004 (not the one that earlier hit Ireland in 1986). Within twelve hours of predicted landfall it veered a little to the right and hit just about outside the warning area. It was forecast to make a landfall near Tampa Bay and came in a hundred miles south at Port Charlotte (the deviation was less than a hundred miles but that was the outcome due to the convergence of track and coastline). This can happen when the upper level steering breaks down or shifts a bit faster than progged. The large scale picture is clear, the storm will make a right turn, weaken and become absorbed into a frontal zone now across central Europe. It will go from a storm force low to basically a frontal wave in 24 hours. The question being, what 24 hours and where. The slower the right turn, the more of the energy will be dissipated over marine areas leading to a weaker outcome on land.

Model spread is fairly small at this point, looks to me like the GEM has the earliest turn and therefore the earliest and more southerly landfall prediction, possibly around Belmullet to Newport. Some are still taking it almost to Malin Head for a landfall. GFS seems to be holding firm with a Donegal Bay track.

73bc61lyohr0mu

Cork removed from the orange warning.

Graces7

Planning a brief exploration when there is enough light.. Black as the proverbial pitch out there. west mayo offshore island

Graces7

Cristian Unimportant Starch wrote: »

Cork removed from the orange warning.

The wording on the orange warning has also slightly changed Refers to " 120 kph and higher" now.

leahyl

Not surprised about Cork, didn’t look like it was gonna be bad at all down here, just your average windy day, if even that

Gaoth Laidir

00Z analysis and 24-hr forecast. Low centre in Donegal Bay and filled more than previously forecast.

The 05Z water vapour shows up that cold front nicely..

Joe Don Dante

It's starting to spit now. Looks like a heavy shower.

adocholiday

Met Eireann have downgraded the average wind speed for my area (South Wicklow so never going to be too bad) by up to 15km at times today. At least that's according to the website.

Gaoth Laidir

ASCAT scan at 22.43Z showed a wide swathe of 40-45 knots on the eastern flank, with just one 50-knot vector (ignore black as it's rain-contaminated and unreliable). As the system weakens the low bias of this method should reduce so I would imagine that the actual winds at that time were fairly close to that. I think we might see the 06Z models downgrade max winds a little further based on this trend.

Meteorite58

ECM 0Z tracking a bit further off the coast and a bit further N and making it's turn later than previous runs.

Oneiric 3

Nice layer/s of Altostratus here now:



Bit of breeze picking up, but with temps at only 8.0c, this must be one of the coldest ex-hurricanes in history.