ATL GUSTAV: Tropical Depression - Discussion

[CrazyC83]

MESOSCALE DISCUSSION 2193
NWS STORM PREDICTION CENTER NORMAN OK
0747 PM CDT SUN AUG 31 2008

AREAS AFFECTED...N-CNTRL GULF OF MEXICO COAST

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 010047Z - 010215Z

TORNADIC THREAT IS EXPECTED TO INCREASE OVERNIGHT AS A MORE
FAVORABLE KINEMATIC/THERMODYNAMIC ENVIRONMENT ASSOCIATED WITH
HURRICANE GUSTAV SHIFTS NWWD TOWARDS THE N-CNTRL GULF OF MEXICO
COAST. A TORNADO WATCH WILL LIKELY BE REQUIRED BY AROUND 03Z.

NUMEROUS MESOCYCLONIC CIRCULATIONS HAVE PERSISTED OVER THE PAST
SEVERAL HOURS OFF THE CNTRL FLORIDA WEST COAST IN THE OUTER
CONVECTIVE BANDS OF HURRICANE GUSTAV. HERE THE NEAR-SHORE
ENVIRONMENT HAS BEEN CHARACTERIZED BY SURFACE DEW POINTS IN THE
MID/UPPER 70S /PER BUOY 42036 AND COASTAL OBSERVATIONS/...ALONG WITH
LARGE LOW-LEVEL HODOGRAPHS /AS SAMPLED BY 00Z TBW RAOB/. FARTHER
N/NW...STRATIFORM RAIN BANDS...LOWER MEAN MIXING RATIOS...AND MORE
MODERATE LOW-LEVEL HODOGRAPHS /PER 00Z LIX AND TLH RAOBS/ SHOULD
MITIGATE OVERALL TORNADIC THREAT IN THE NEAR-TERM.
HOWEVER...EXPECTED NWWD TRACK OF HURRICANE GUSTAV /PER LATEST NHC
GUIDANCE/ WOULD SUGGEST EXTRAPOLATION OF THE MORE FAVORABLE
KINEMATIC PROFILE AND RICHER BOUNDARY LAYER MOISTURE WILL
CORRESPONDINGLY SHIFT NWWD DURING THE NEXT SEVERAL HOURS. AS
SUCH...TORNADO POTENTIAL WILL INCREASE DURING THE LATE EVENING INTO
EARLY MON.

..GRAMS.. 09/01/2008


ATTN...WFO...TAE...MOB...LIX...

29979059 30598985 30968876 31068734 30848572 30268470
29528440 29268532 29338693 28898886 28579022 29079071

[KWT]

Yep Sabanic, must be pretty close by now I reckon looking at the radar, maybe within the next 30 mins the rains will start.

The good thing is with its foward speed it should clear out pretty quickly the main danger zone but there does seem to be a good chance this slows right down, flooding may well be an issue E.Texas.

[ConvergenceZone]

Latest pass didnt find lower pressures. Excellent news.

I'm not really surprised to be honest as the eyewall has become a little open on the eastern side yet again, think its back to holding steady again thanks to the big convective bursting.

If that is the case, strengthening probably won't happen from here on out, BUT I don't think it will get much weaker either, because it's running out of time as fast as it's moving towards land...

[Steve Cosby]

In reality, what is interesting about shear in TC's versus Supercells is that in TC's, it inhibits development while, in Supercells, it is the exact opposite. That is, in fact, what causes my confusion.

[HarlequinBoy]

Is the velocity out of the New Orleans radar different?

[HURAKAN]

31/2345 UTC 26.9N 87.6W T5.5/5.5 GUSTAV -- Atlantic Ocean

Dvorak also agrees, 102 knots.

[jaxfladude]

...... Non-Stop Prayer Activated......

[Enzo Aquarius]

I have to agree with what has been said, with these tornado warnings and the strength of this band in the N.O. area, shouldn't a Tornado Watch be issued?

[ekal]

The eye is becoming apparent on IR. Although the NE Quad looks a bit weak in this shot, one more convective burst will fill it in. Very worrisome trend.

[Brent]

Dry air is going bye-bye. Continues to look better.

[cheezyWXguy]

The eye is becoming apparent on IR. Although the NE Quad looks a bit weak in this shot, one more convective burst will fill it in. Very worrisome trend.

Indeed. Everyone please note that the eye is not the blue spot in the ne part of the cdo, but is actually the yellow in the very middle.

[RainWind]

Thanks for the prayers, they are going to be needed. Time to begin hunkering down in the hall. RW

[KWT]

Ne eyewall looks pretty weak again and the eyewall is clearly open once again. Still it looks a little less so then about 30 minutes ago so it may well be closing itself back up and forming a tighter eye feature, needs to be watched.

CZ, I don't think we will see much change from now on, odds on this comes in as a cat-3, its just exactly where about in the category, low end, middle or top?

[PhillyWX]

Ed Rappaport was on WDSU in NoLa and did not rule out a low end Cat 4 at landfall...but said a Cat 3 is probably what ends up resulting.

[stormy1970al]

You can see lightening from the South of where I live and a light drizzle. I think we are in for a rough night. And prayers for the people of LA.

[PhillyWX]

http://philadelphiaweather.blogspot.com ... ns-tv.html

Updated imagery from the 8 ET hour from Fox 8 and WDSU in New Orleans.

[Enzo Aquarius]

CZ, I don't think we will see much change from now on, odds on this comes in as a cat-3, its just exactly where about in the category, low end, middle or top?

NHC predicts top, but we shall see.

[soonertwister]

I guess it might be mentioned now that the strongest forecast landfall for Gustav was when he was cat-5 south of Cuba.

That's only 15 kts above where he is now.

And now Fox suggests that Gustav may hit near Lake Charles, or even on the Texas coast. I think that's a ridiculous assertion to make based upon one particular new model run.

[Downdraft]

I'm afraid I have to call out the SPC here on the gross lack of a tornado watch.

Should there be anyone there to worry about it?

[Wx_Warrior]

Sanibel, when you say OFFICIAL, you better post a link or say IMHO...I havent seen, heard or read anything of that nature where someone says LAFAYETTE will be the OFFICIAL landfall.

And I'm not talking about what some dude off Fox or CNN says.....