Tropical Storm GABRIELLE (ATL): Global & BAM Models

[cycloneye]

Initialized Sep 05 00Z

Good loop Sandy.That is the 00z run.When you get the 6z intensity loop post it rapidly.

[Thunder44]

It seems like every run the GFDL and GFS keep shifting there tracks west or east. While the ECMWF remains relatively consistent with landfall in the Carolinas. I think the ECMWF has had so far this season, better handle on the subtropical ridge in the Atlantic, building back west, and it will come out on top again.

[PhillyWX]

It seems like every run the GFDL and GFS keep shifting there tracks west or east. While the ECMWF remains relatively consistent with landfall in the Carolinas. I think the ECMWF has had so far this season, better handle on the subtropical ridge in the Atlantic, building back west, and it will come out on top again.

It will be interesting to watch the models over the next couple of days. The EURO's track was very Gaston-like, curving it through the Carolinas and out to sea over VA and Delmarva. Some variations in timing for landfall, how fast the trough moves in from the west, and the axis of the trough can change many different features of this storm's future path and destination.

[Thunder44]

6z GFDL shows a Cat 2 or 3 into SC on Sunday AM:

http://moe.met.fsu.edu/cgi-bin/gfdltc2. ... =Animation

[weatherwoman]

jb is leaning towards nc hes going with the euro model between wilm and the cape i agree with him and say we better start getting ready

[HURAKAN]

It should be noted that even though many are calling Ophelia and Gaston as possible references, none of these systems traveled as far east as 99L has done.

Gustav formed exactly where 99L is located.

[brunota2003]

Seriously though, if this thing ever gets going and actually hits land, we'll have a kick-butt 10-meter wind tower with a live web cam on it set up as close to the strongest wind area as possible. You will be able to watch it update every 60 seconds- free of charge. We will also have a digital data log of the data collected for future reference.

Yes Mark, I'll be able to watch it free of charge alright, as it comes right over my head

[Meso]

http://moe.met.fsu.edu/cgi-bin/hwrftc2. ... =Animation

The 06z HWRF

[ronjon]

This mornings early discussion from HPC indicates that the Atlantic Ridge may be a little stronger than predicted yesterday so as a result we've seen westward shifts of the models into either GA or SC. This will be an interesting situation over the next few days as to just how strong that ridge gets - the trend this year is for these ridges to amplify once these storms deepen rapidly. Don't know if that's going to be the case with this one but its going to be nail-biting time from GA to Hatteras on this one.

From HPC preliminary disc:

00Z ECMWF AND NOGAPS ALL TRACK THE DEVELOPING CYCLONE OVER
THE ATLANTIC TO THE LEFT OF THE OPERATIONAL GFS...MAKING LANDFALL
ANYWHERE FROM THE GEORGIA COAST TO THE LOWER NORTH CAROLINA COAST.

[Bane]

:uarrow: Look how slow GFDL moves this,before it makes landfall in South Carolina.

that would be beneficial to help our 17 inch rainfall deficit, but all of it at once would be bad. we would experience the same type of flooding that we did when floyd hit in 1999.

[cycloneye]

197
WHXX01 KWBC 051237
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1237 UTC WED SEP 5 2007

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL992007) 20070905 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
070905 1200 070906 0000 070906 1200 070907 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 29.1N 71.5W 29.1N 71.1W 28.9N 71.6W 28.6N 72.8W
BAMD 29.1N 71.5W 30.0N 69.8W 30.9N 68.8W 31.7N 69.2W
BAMM 29.1N 71.5W 29.3N 70.6W 29.4N 70.5W 29.7N 71.4W
LBAR 29.1N 71.5W 29.5N 70.0W 30.3N 68.5W 30.9N 66.9W
SHIP 25KTS 30KTS 36KTS 43KTS
DSHP 25KTS 30KTS 36KTS 43KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
070907 1200 070908 1200 070909 1200 070910 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 28.6N 74.2W 30.3N 75.0W 33.7N 74.9W 36.7N 73.1W
BAMD 32.4N 70.3W 35.1N 73.8W 38.8N 74.2W 41.6N 67.1W
BAMM 30.2N 72.8W 32.4N 75.6W 35.3N 77.0W 38.0N 74.9W
LBAR 32.0N 64.5W 34.1N 60.0W 34.6N 55.2W 33.3N 48.5W
SHIP 51KTS 62KTS 62KTS 55KTS
DSHP 51KTS 62KTS 49KTS 32KTS

...INITIAL CONDITIONS...
LATCUR = 29.1N LONCUR = 71.5W DIRCUR = 95DEG SPDCUR = 8KT
LATM12 = 29.4N LONM12 = 73.6W DIRM12 = 93DEG SPDM12 = 8KT
LATM24 = 29.3N LONM24 = 75.3W
WNDCUR = 25KT RMAXWD = 50NM WNDM12 = 25KT
CENPRS = 1008MB OUTPRS = 1013MB OUTRAD = 210NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

Pressure down one millibar.

[Lowpressure]

http://moe.met.fsu.edu/cgi-bin/hwrftc2.cgi?time=2007090506-invest99l&field=Sea+Level+Pressure&hour=Animation

The 06z HWRF

That run looks to be considerably weaker with the system.

[weatherman21]

After observing the latest models run of the GFS and the WRF, both agree upon an upper-layer trough that will be interacting with the system which will also aid in pushing the storm further east over the next 24 hours or so. Once the low pressure area reaches about 72W longitude early tomorrow morning, the GFS and WRF both stall the system. After the trough exists to the east and the high pressure ridge developes to the north of the area of low pressure, both models forecast a wnw track back towards the Carolina coastline. Though the WRF only goes out 3 1/2 days, there appears to be some agreement among the GFS and the WRF until that time. By the end of the WRF model run which is Saturday afternoon, the model indicates the storm will be closing in on the North Carolina coast, approaching from the SE. In regards to the forecast therafter, The GFS has been trending back and forth with each run, taking the storm offshore in one run and bringing the storm inland in another run. I guess it all depends on the timing of when the high pressure ridge developes behind the upper-layer trough and begins to steer the system back towards the wnw.
Whether the models are correct is highly uncertian and given the trend of the recent model runs, I consider these solutions for no more than a possibility. Although, since I live in eastern North Carolina, I will be watching this storm very closely. I have posted below, a few screen captures of the 6Z WRF model run showing the low pressure area. In the following images I have MSL Pressure, Precipitable Water, and 700MB Winds.

WRF Forecast for 15Z tomorrow morning; the model has the system stalled near 28N, 72W.


WRF Forecast for 15Z on Friday; the model takes the low pressure area towards the wnw.


WRF Forecast for 18Z Saturday:

[LarryWx]

0z ECMWF, takes it further back west toward the SC coast by the weekend again:

http://www.meteo.psu.edu/~gadomski/ECMW ... floop.html

0z NOGAPS, takes it back toward Georgia:

http://www.meteo.psu.edu/~gadomski/NOGA ... sloop.html

The big problem with the credibility of both of these two model runs is that they have the low too far west! The 0Z Euro never gets the low any further east than ~73W and the 0Z NOGAPS ~74W! The low is already near 71.5W. I don't see how these runs can be all that
useful.

What these three model runs do imho is to way overdo the threat to GA and lower SC.

Any other opinions on this issue? I haven't seen anyone mention this yet.

[LarryWx]

803
WHXX04 KWBC 051121
CHGQLM
ATTENTION...NATIONAL HURRICANE CENTER

NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR

TROPICAL DEPRESSION INVEST 99L

INITIAL TIME 6Z SEP 5

DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT
REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD
NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC
OFFICIAL FORECAST.


FORECAST STORM POSITION

HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)

0 29.4 72.9 85./ 8.0
6 29.4 72.4 84./ 3.9
12 29.3 71.8 103./ 5.2
18 29.3 71.5 90./ 3.2
24 29.4 71.4 18./ .6
30 29.4 71.8 271./ 3.6
36 29.2 72.4 258./ 4.6
42 29.2 73.1 269./ 6.0
48 29.5 74.1 285./ 9.7
54 29.8 75.1 287./ 8.7
60 30.2 76.1 290./ 9.8
66 30.3 77.1 276./ 8.7
72 30.6 77.9 290./ 7.8
78 30.8 78.5 288./ 5.6
84 31.2 78.9 317./ 5.0
90 31.8 79.2 331./ 6.3
96 32.3 79.8 311./ 7.0
102 32.7 80.3 308./ 5.5
108 33.0 80.6 319./ 4.8
114 33.2 80.8 315./ 2.2
120 33.4 80.8 349./ 2.1
126 33.8 80.7 22./ 4.2

This model is also too far west in its early stages. Note that it has the low at 72.4 west at 12Z today. Well, as of 12Z today, it is already near 71.5 W. So, here is still another model that imho is moving the storm further west than would otherwise be the case. Therefore, this model is also overdoing the threat to the lower SC coast.

[ronjon]

Latest model plots.

[ronjon]

Larrywx, I agree with you that initial position plays a role in where this system may end up but the other factor is the strength of the Atlantic Ridge - you'll notice that the NOGAPs run above obviously has the strongest ridge as it pushes the storm west over 10 deg longitude compared with the GFS. Still some doubt in my mind as to how strong this ridge will become and does a rapidly deepening storm also "pump up" the ridge like it appears to have done with Dean and Felix. I'm not saying this system will reach CAT 4 or 5 status, but I could see a major hurricane CAT 3 out of it.

[Tampa Bay Hurricane]

Larrywx, I agree with you that initial position plays a role in where this system may end up but the other factor is the strength of the Atlantic Ridge - you'll notice that the NOGAPs run above obviously has the strongest ridge as it pushes the storm west over 10 deg longitude compared with the GFS. Still some doubt in my mind as to how strong this ridge will become and does a rapidly deepening storm also "pump up" the ridge like it appears to have done with Dean and Felix. I'm not saying this system will reach CAT 4 or 5 status, but I could see a major hurricane CAT 3 out of it.

Agreed. The models have underestimated the ridge with dean/felix, I could see 99L sweeping the coast from GA to
SC to NC possibly, which would bring heavy impacts to 3 states: GA, SC, as well as NC.

In any case, NC folks should be preparing, as that looks to
get some heavy rain/wind regardless of exact landfall point.

[flwxwatcher]

I read that discussion by the HPC also. It will be interesting to see the Model trends once they fly a Gulfstream Mission and that data is ingested into the Models.

[jdray]

This is a threat to Daytona Beach north to Cape Hatteras still.


Most models have under estimated the ridge the past few storms.