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Hurricane Isaac, Part 3 - Analysis and Forecasting Thread


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Just my opinion but this is just about the worst isaac has looked all day just doesn't look to healthy now at all actually surprised it's still has 70mph winds on the 2am adv.......

Recon just found flight level winds as well as SFMR surface wind estimates which both clearly support 60kt/70mph. The pressure is also now at the lowest it has been at any point.

Anyways, new vortex, 978mb on the drop, eye down from 40nm to 30nm since the last pass, but still open.

000

URNT12 KNHC 280614

VORTEX DATA MESSAGE AL092012

A. 28/05:37:50Z

B. 27 deg 17 min N

087 deg 44 min W

C. 850 mb 1249 m

D. 47 kt

E. 175 deg 71 nm

F. 266 deg 36 kt

G. 174 deg 61 nm

H. 978 mb

I. 17 C / 1541 m

J. 22 C / 1524 m

K. 22 C / NA

L. OPEN SE-SW

M. C30

N. 12345 / 08

O. 0.02 / 1 nm

P. AF309 2909A ISAAC OB 14

MAX OUTBOUND AND MAX FL WIND 76 KT N QUAD 05:48:00Z

MAX OUTBOUND SFMR SURFACE WIND 60 KT N QUAD 05:46:00Z

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Wow...00z Euro is a carbon copy of the what some labeled "Strange stall/drift west into NE Texas scenario the GFS has been showing for like 10 runs now. Guess its finally picking up on that trough staying to the NE.

ecmmslpuv850gulftropica.png

usahgt500mb048y.gif

ecmmslpuv850gulftropica.png

Yes, the ECMWF is now showing the GFS solution - now that the GFS has given up on it and is showing the NW to N track that the ECMWF was showing. Man, this has been a fun storm for the models. Looks like the UKMET is in between the two solutions. If the ECMWF is right this still has a day and half to two days over water.

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Yes, the ECMWF is now showing the GFS solution - now that the GFS has given up on it and is showing the NW to N track that the ECMWF was showing. Man, this has been a fun storm for the models. Looks like the UKMET is in between the two solutions. If the ECMWF is right this still has a day and half to two days over water.

Yep. Landfall wouldn't be until Wednesday morning if the EURO has it's way.

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Really hesitating to gain latitude, moving due Westward along 27.3N based on recon fixes, recon looks to have it now to 27.3N 88.1W. Extrap down to 977.4mb

Yeah, you can see that in satellite. Moving slowly due west.

Just my opinion but this is just about the worst isaac has looked all day just doesn't look to healthy now at all actually surprised it's still has 70mph winds on the 2am adv.......

Not meaning to argue, but trust me the convective organization looks better now than it did this evening. There is much more in the way of cold convection surrounding the center than 6-9 hours ago when the northern half of the storm was devoid of convection. I am not saying it looks wonderful, but it definitely looks better.

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977mb on the drop, 1kt wind at surface

Looks like we are getting better and better winds. Pretty substantial band now of 60-75 kt FL winds east of the center outbound with a number of 50-55 kt SFMR values.

Will be interesting to see what NHC makes of this westward wobble along with the shift of the EC track. It does look like the EC is the only model that goes that far west, although the UK certainly did shift somewhat west as well 00Z GFS/GFDL/HWRF continue on a similar track to SE LA or MS coast.

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New vortex.

000

URNT12 KNHC 280757

VORTEX DATA MESSAGE AL092012

A. 28/07:26:10Z

B. 27 deg 19 min N

087 deg 59 min W

C. 850 mb 1234 m

D. 52 kt

E. 262 deg 12 nm

F. 003 deg 57 kt

G. 265 deg 22 nm

H. 977 mb

I. 16 C / 1528 m

J. 22 C / 1526 m

K. 19 C / NA

L. OPEN SW-NE

M. C26

N. 12345 / 08

O. 0.02 / 1 nm

P. AF309 2909A ISAAC OB 18

MAX OUTBOUND AND MAX FL WIND 78 KT E QUAD 07:52:00Z

MAX OUTBOUND SFMR SURFACE WIND 54 KT E QUAD 07:44:30Z

Also worth noting that there is a rather large region of 70kt+ flight level winds in the East quad.

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New vortex.

000

URNT12 KNHC 280757

VORTEX DATA MESSAGE AL092012

A. 28/07:26:10Z

B. 27 deg 19 min N

087 deg 59 min W

C. 850 mb 1234 m

D. 52 kt

E. 262 deg 12 nm

F. 003 deg 57 kt

G. 265 deg 22 nm

H. 977 mb

I. 16 C / 1528 m

J. 22 C / 1526 m

K. 19 C / NA

L. OPEN SW-NE

M. C26

N. 12345 / 08

O. 0.02 / 1 nm

P. AF309 2909A ISAAC OB 18

MAX OUTBOUND AND MAX FL WIND 78 KT E QUAD 07:52:00Z

MAX OUTBOUND SFMR SURFACE WIND 54 KT E QUAD 07:44:30Z

Also worth noting that there is a rather large region of 70kt+ flight level winds in the East quad.

Contracting eye and a widening temp gradient too.
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Haha... I saw this conversation happening sooner or later. I start posting about the HRRR and everyone follows suit. Here is my take on it.

The HRRR is still an experimental model being developed by ESRL. At chris87 mentioned, its huge advantage is that it uses no cumulus parameterization, because the resolution of the model is so fine, it is able to properly resolve convection. That means no parameterization (or added unknown) that can be a large source of error (Especially in the tropics where convection is highly prevalent). In order to not use a cumulus parameterization, you need to get down to 3-4 km which is where the HRRR is. Another big advantage (that I didn't see mentioned here) its its data assimilation. Instead of the GFDL and HWRF that use vortex bogusing (I think) to artificially create TCs that they then integrate forward in time, we have actual data that creates the initial conditions, taken both from radar reflectivity and olr from the RAP model. Its not perfect, and the model having to downscale from 13 km to 3 km creates a lot of error, but its superior to the vortex bogusing techniques in my opinion, and perfectly fine for short range forecasts. They folks that work on the HRRR are working to get it down to 3 km for data assimilation, which should improve these forecasts further, but thats still down the road. Notice when you animate the radar and outgoing longwave radiation that you see the model quickly adjust from the 13 km initial conditions to its native resolution... thats the downscaling effect that takes place as the model integrates forward in time. Not all models that have this high resolution are created equal... the power of HRRR is that its an already good model coupled with an ever improving data assimilation scheme.

Those that complained that it does poor with severe weather forecasting are not using it for its correct purpose. Of course if you are expecting the HRRR to nail the location and time of individual supercells or even ordinary thunderstorms you are going to constantly be burned. The model is not perfect. What it does become more useful is in forecasting different convective regiemes, and different convective modes. It won't tell you exactly where a storm is going to develop, but it can usually do a good job telling you what the storm mode for a particular day will be (linear, supercellular, multicell ect.)

For forecasting TCs, it has mainly been unproven (since its still relatively new and its domain only covers where it has access to the RAP, which is mainly over land). However, given how god awful the GFDL and HWRF are with their TC initializations, the HRRR in many ways is likely superior to these models for the time range that it forecasts. The HWRF in particular is what I like to call out, since its pretty much the perfect example of a model that doesn't belong in the tropics, since its model physics were based off the NAM. If they wanted to create a high resolution model for TCs, they should have based it off code other than the NAM which is specifically tuned to work well ONLY in the mid-latitudes.

The most useful tool I think HRRR should be used for is its ability to create dprog/dt output... which lets you pick up on short term trends. Since it does read in real data hourly, it can catch new reflectivity data that shows a system moving off course from a given forecast. For example, it seems to be capturing the short term slowdown of Isaac pretty well, when it slowed down the forward progression of the eye-like feature on the reflectivity animation I showed earlier.

I don't claim to be very knowledgeable on the nuts and bolts of HRRR, but from what I've seen so far (with its performance with Alberto [the ONLY model to pick up on its genesis] and Beryl) I'm lead to believe it has decent utility in the tropics.

For more information go here: http://ruc.noaa.gov/hrrr/

Bingo. The best way to use it imo. Never really used it operationally as far as TCs are concerned, so it will be interesting.

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Pretty much what I expected the IR to look for now. He's trying, but still a little ragged looking. Perhaps today he begins to get a little more organized. Interesting euro run to say the least.

This thing looks like sh*t...warming cloud tops (especially east side), discombobulated convective blobs, dry air. I wouldn't be surprised to see it make LF with 65-70knot winds giving it benefit of the doubt. Best 4 performing models avg. peak intensity of 64 knots. Here are 3 below.

post-3697-0-22094600-1346144547_thumb.pn

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This thing looks like sh*t...warming cloud tops (especially west side), discombobulated convective blobs, dry air. I wouldn't be surprised to see it make LF with 65-70knot winds giving it benefit of the doubt. Best 4 performing models avg. peak intensity of 64 knots. Here are 3 below.

post-3697-0-22094600-1346144547_thumb.pn

I didn't believe it would get super organized overnight, so about what I thought it would do so far...although I did think it would be at least 65kts in this package before I went to bed last night. Still got some work to do.

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I didn't believe it would get super organized overnight, so about what I thought it would do so far...although I did think it would be at least 65kts in this package before I went to bed last night. Still got some work to do.

Thanks for bringing some sense in to the thread last night. Was with with you in spirit, LOL. Just didn't want to p*ss in anyone's cheerios. I posted my thoughts on the intensity back on sat. and they seem to been panning out.

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This thing looks like sh*t...warming cloud tops (especially east side), discombobulated convective blobs, dry air. I wouldn't be surprised to see it make LF with 65-70knot winds giving it benefit of the doubt. Best 4 performing models avg. peak intensity of 64 knots. Here are 3 below.

I will have to give you kudos QVectorman... those models you showed like a day or two ago, the best performing ones up to that point which were not showing much intensification... those ended up being right.

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Product: Air Force Vortex Message (URNT12 KNHC)

Transmitted: 28th day of the month at 09:25Z

Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)

Storm Number & Year: 09L in 2012

Storm Name: Isaac (flight in the North Atlantic basin)

Mission Number: 29 seeall.png

Observation Number: 22

A. Time of Center Fix: 28th day of the month at 8:43:20Z

B. Center Fix Coordinates: 27°26'N 87°58'W (27.4333N 87.9667W) viewmap.png

B. Center Fix Location: 213 miles (342 km) to the SSW (192°) from Pensacola, FL, USA.

C. Minimum Height at Standard Level: 1,239m (4,065ft) at 850mb

D. Estimated (by SFMR or visually) Maximum Surface Wind: 50kts (~ 57.5mph)

E. Location of the Estimated Maximum Surface Wind: 78 nautical miles (90 statute miles) to the NE (45°) of center fix

F. Maximum Flight Level Wind Inbound: From 143° at 71kts (From the SE at ~ 81.7mph)

G. Location of Maximum Flight Level Wind Inbound: 83 nautical miles (96 statute miles) to the NE (46°) of center fix

H. Minimum Sea Level Pressure: 977mb (28.85 inHg)

I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,526m (5,007ft)

J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 21°C (70°F) at a pressure alt. of 1,525m (5,003ft)

K. Dewpoint Temp (collected at same location as temp inside eye): 21°C (70°F)

K. Sea Surface Temp (collected at same location as temp inside eye): Not Available

L. Eye Character: Open in the southwest

M. Eye Shape & Diameter: Circular with a diameter of 32 nautical miles (37 statute miles)

N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature

N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 850mb

O. Navigation Fix Accuracy: 0.02 nautical miles

O. Meteorological Accuracy: 2 nautical miles

Remarks Section:

Maximum Flight Level Wind: 78kts (~ 89.8mph) in the east quadrant at 7:52:00Z

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