ATL: IRMA - Models

[nascarfan999]

Looking closely at the Euro its is nearly out to see because a 500mb plus low deveops over virginia just as IRMA approaches NC and shoves it nne.. looks like a transient feature. next run likely will be back west again.\

I was going to ask about that because without that magic low popping up I sure thought Irma was heading for the Carolinas. I wouldn't want to hang recurve hopes on that low popping up.

[meriland29]

So what are you guys implying, the Irma seems only likely to hit the states if she is at the right speed? That she is most likely going to not hit the states?

[wzrgirl1]

just no Aric.

Why not Alyono? So far we've seen during the short term forecasts that it's a bit slower and further WSW, anything after 5 days is a toss-up. I feel that everyone along the eastern seaboard from SE FL to Maine are at equal chances of some sort of effect.

models are trending FASTER not slower. Storm is moving at a good clip. The idea of the storm moving slow enough so that the ridge forces it into Florida are about gone now. Only chance is for this to move at 18 kts and get to Florida before it encounters the trough

How fast is Irma going now?

[forecasterjack]

Looking closely at the Euro its is nearly out to see because a 500mb plus low deveops over virginia just as IRMA approaches NC and shoves it nne.. looks like a transient feature. next run likely will be back west again.

If that low gets absolutely any stronger, it'll suck Irma right in. Such a volatile setup

that low also keeps the weakness after the trough lifts out which is why it does not make it as far west.. definitely looks transient as its not on any other model run as is small and weak but enough to keep the weakness

There are two ULL's here. The first is lifting out as Irma approaches. That's located in NE Canada when Irma's in the Bahamas. However, it leaves behind a weakness as you said. On the S end of that weakness/vorticity chain/boundary, another ULL forms. If that new ULL is even a little stronger than depicted on the 12Z ECMWF, Irma hooks left into it. Can see the whole thing evolve: https://weather.us/model-charts/euro/79 ... 1800z.html

[birddogsc]

When will we get better synoptic information? I know balloon launches are daily, but when might they trigger a G-IV flight?

[northjaxpro]

Why not Alyono? So far we've seen during the short term forecasts that it's a bit slower and further WSW, anything after 5 days is a toss-up. I feel that everyone along the eastern seaboard from SE FL to Maine are at equal chances of some sort of effect.

models are trending FASTER not slower. Storm is moving at a good clip. The idea of the storm moving slow enough so that the ridge forces it into Florida are about gone now. Only chance is for this to move at 18 kts and get to Florida before it encounters the trough

How fast is Irma going now?

11 a.m. advisory had it moving at 15 mph

[forecasterjack]

When will we get better synoptic information? I know balloon launches are daily, but when might they trigger a G-IV flight?

000
NOUS42 KNHC 021445
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT SAT 02 SEPTEMBER 2017
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 03/1100Z TO 04/1100Z SEPTEMBER 2017
TCPOD NUMBER.....17-093

I. ATLANTIC REQUIREMENTS
1. HURRICANE IRMA

FLIGHT ONE -- NOAA 42 FLIGHT TWO -- NOAA 42
A. 03/2100Z A. 04/0900Z
B. NOAA2 0111A IRMA B. NOAA2 0211A IRMA
C. 03/1900Z C. 04/0700Z
D. 17.5N 49.0W D. 17.2N 51.0W
E. 03/2030Z TO 04/0030Z E. 04/0830Z TO 04/1230Z
F. SFC TO 10,000 FT F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK:
A. BEGIN 6 HRLY FIX MISSIONS ON HURRICANE IRMA AT 04/1800Z
NEAR 17.2N 52.5W.
B. A G-IV SYNOPTIC SURVEILLANCE MISSION AROUND IRMA
WITH TAKEOFF OF 04/1730Z.

II. PACIFIC REQUIREMENTS.
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.


$$
WJM

[Aric Dunn]

When will we get better synoptic information? I know balloon launches are daily, but when might they trigger a G-IV flight?

G IV flights will start in a few days im assuming. but that will help with the ridging over the atlantic. we have plenty of data over the mainland.

[otowntiger]

just no Aric.

Why not Alyono? So far we've seen during the short term forecasts that it's a bit slower and further WSW, anything after 5 days is a toss-up. I feel that everyone along the eastern seaboard from SE FL to Maine are at equal chances of some sort of effect.

.

models are trending FASTER not slower. Storm is moving at a good clip. The idea of the storm moving slow enough so that the ridge forces it into Florida are about gone now. Only chance is for this to move at 18 kts and get to Florida before it encounters the trough

But isn't the speed of the trough setting up also a factor at play? I would think it's speed isn't set in stone. It's not all about the forward speed of the hurricane is it?

[Alyono]

ECMWF ensembles. Uncertainty abounds.

That looks further east to me. Am I wrong? Where is the 0z EPS?

0Z

looks like more 12Z EC ensembles have a hit than 0Z

[forecasterjack]

That looks further east to me. Am I wrong? Where is the 0z EPS?

0Z

looks like more 12Z EC ensembles have a hit than 0Z

If you want you can flip through each member individually and count 'em up: https://weather.us/model-charts/euro/79 ... 1800z.html just use menu to left of image to select different members and compare. Someone on here put together a GIF of all the EPS solutions a couple days ago, that was cool to watch. Not enough time to put it together myself, but maybe someone else does

[LarryWx]

I had been thinking of raising the chance in my mind at a CONUS landfall from 25%, but the 12Z Euro/ and 2 most recent EPS are telling me to hold on for now.

Another thing to keep in mind is the recent bias of too strong of an eastern N.A. ridge and the opposite in the west for the GEFS...perhaps this means higher chance for recurve than what GEFS has been showing??

http://www.cpc.noaa.gov/products/fcst_e ... _bias.html

[Cunxi Huang]

12z. CMC (plum) control (orange), UKMO (white), HWRF (voilet), CTCX (green), HMON (yellow), Mean (navy), FNMOC (orange) control (orange), GEFS (red) control (green), FEO (blue)

[Blown Away]

Based on 12z Euro I would think the 5 day track will need to be adjusted S... Maybe closer to NE Caribbean...

[jlauderdal]

Happy hour gfs will come west and we will be back where we started when the euro ran..

[GeneratorPower]

Happy hour gfs will come west and we will be back where we started when the euro ran..

With such a complex pattern I really hope we get clarity. Not good for anyone to have uncertainty.

[hohnywx]

Happy hour gfs will come west and we will be back where we started when the euro ran..

With such a complex pattern I really hope we get clarity. Not good for anyone to have uncertainty.

We are 7+ days out from a possible CONUS landfall. There will not be any clarity gained. Just another possible solution.

[birddogsc]

G IV flights will start in a few days im assuming. but that will help with the ridging over the atlantic. we have plenty of data over the mainland.

That's my thought... Better data about the ridge should help determine the path/timing of the trough.

2. SUCCEEDING DAY OUTLOOK:
A. BEGIN 6 HRLY FIX MISSIONS ON HURRICANE IRMA AT 04/1800Z
NEAR 17.2N 52.5W.
B. A G-IV SYNOPTIC SURVEILLANCE MISSION AROUND IRMA
WITH TAKEOFF OF 04/1730Z.

So two days to get this data...

[Cunxi Huang]

The environment in which Irma is embedded continues to show mixed
signals during the forecast period, and the intensity guidance
responds to this by ranging between little and slow intensification.
The hurricane is currently suffering some impact of sea surface
temperatures of about 27C and mid-level dry air entrainment. Later
in the period, Irma should encounter warmer water and increasing
moisture at a time when the vertical wind shear may be increasing.
Given the uncertainty on when all of the ingredients may come
together, the new intensity forecast is the same as the previous
forecast and calls for gradual intensification through the next
5 days. An alternative forecast scenario is that Irma gets
significantly stronger than forecast near the end of the forecast
period if the shear is less than currently expected.

[GCANE]

Forecast track of the three best performing models so far for Irma: TVCN, NVGM, ECMO