Post Tropical Cyclone Debby. Exiting E Over The Atlantic

[srainhoutx]

TROPICAL STORM DEBBY DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012
1000 AM CDT SUN JUN 24 2012

IT IS A VERY DIFFICULT AND HIGHLY UNCERTAIN FORECAST THIS MORNING.
DEBBY HAS BEEN MOVING VERY SLOWLY TOWARD THE NORTHEAST...040 AT 3
KNOTS...WHILE THE WIND RADII HAVE BEEN EXPANDING IN THE EASTERN
SEMICIRCLE. THIS HAS PROMPTED ADDITIONAL TROPICAL STORM WARNINGS
AND WATCHES FOR PORTIONS OF THE FLORIDA COAST.

DEBBY CONTINUES TO BE SHEARED WITH MOST OF THE THUNDERSTORM ACTIVITY
NORTH AND EAST OF THE CENTER. THIS SHEAR IS EXPECTED TO CONTINUE
FOR THE NEXT DAY OR SO...ALTHOUGH SOME DECREASE IN THE SHEAR IS
POSSIBLE AFTER THAT...PARTICULARLY IF THE ECMWF VERIFIES. THE
OFFICIAL FORECAST IS A LITTLE LESS AGGRESSIVE THAN THE PREVIOUS
FORECAST...BUT REMAINS ABOVE MOST OF THE EXPLICIT INTENSITY
GUIDANCE.

THE TRACK FORECAST IS EVEN MORE COMPLEX. THE GFS INSISTS ON A TRACK
TOWARD THE NORTHEAST AS DEBBY BECOMES EMBEDDED WITHIN A LARGE
MID-LATITUDE TROUGH. HOWEVER...THE ECMWF AND THE HWRF BUILD A RIDGE
TO THE NORTH OF DEBBY AND FORECAST A WESTWARD TRACK. GIVEN THE
WESTWARD TURN INHERITED FROM THE PREVIOUS FORECAST...AS WELL AS THE
HISTORICAL STRONG RECORD OF THE ECMWF...THE NEW OFFICIAL FORECAST
MOVES DEBBY INITIALLY A LITTLE BIT TO THE NORTHEAST TO REFLECT
CURRENT TRENDS BUT THEN TURNS THE CYCLONE BACK TOWARD THE WEST OR
WEST-NORTHWEST IN 24 TO 36 HOURS. A MAJORITY OF THE GFS ENSEMBLE
MEMBERS NOW ARE CONSISTENT WITH THE DETERMINISTIC RUN...WHICH WAS
NOT THE CASE YESTERDAY...MAKING A STRONGER CASE FOR THE EASTWARD
SOLUTION. WE MUST BE READY TO MAKE A CHANGE OF THE FORECAST TRACK
AT ANY TIME.


FORECAST POSITIONS AND MAX WINDS

INIT 24/1500Z 28.0N 86.2W 50 KT 60 MPH
12H 25/0000Z 28.5N 85.8W 50 KT 60 MPH
24H 25/1200Z 28.5N 85.8W 50 KT 60 MPH
36H 26/0000Z 28.5N 86.2W 55 KT 65 MPH
48H 26/1200Z 28.7N 87.0W 60 KT 70 MPH
72H 27/1200Z 29.0N 88.4W 65 KT 75 MPH
96H 28/1200Z 29.5N 90.5W 45 KT 50 MPH
120H 29/1200Z 30.0N 91.5W 30 KT 35 MPH

$$
FORECASTER AVILA

[weatherguy425]

You know, I'd almost be willing to trade power outages for a good rain. All I want is my typical southeast Texas summer back. Hoping even if we aren't affected by Debby, that she'll only further weaken the ridge and perhaps leave behind a south/southeasterly flow for at-least some seabreeze storms to fire for a few days.

[gocuse22]

IMO

Port O Connor to Mobile have the best chance for this system

[gocuse22]

If you are in Texas, DO NOT let your guard down. We are still in the cone, with a highly uncertain system like this it could easily swing back west.

[Scott747]

It has been 'decoupling' and taking it more towards the NE and that scenario for a Texas hit is running out of time.

Our best bet would for it to stall as the trough exits and then the rebuilding H sends it back to the W as a coastal runner with hints of a WSW movement. Plausible and would match up with some of the early modeling albeit off on timing.

What NE movement are you seeing because I have been seeing only north and now it has really slowed down/ gone stationary with convection building off to the west.

Latest disco confirmed it.

[gocuse22]

These 12z model runs will be VERY telling.

[weatherguy425]

Sigh, NAM keeps it towards Florida. Meanwhile we're back in a >100 degree oven.

[srainhoutx]

For what it's worth, the 12Z WRF/NMM (NAM) solution suggests a very slow motion through 84 hours. There are a couple of features upstream that will need to be monitored. Two short waves are diving SE along the E flank of the building Ridge. One is nearing the Tennessee Valley while the other in dropping SE near North Dakota. The upper low has brought in dry air and convection continues off to the E of the decoupled circulation. As Scott mentioned, the Coastal runner or a W to WSW movement had been suggested by some computer models. As the additional data continues to be ingested, things will become a bit clearer as the day progresses. As of now, it does appear SE Louisiana on E to the Tallahassee area is most favored for a land falling Debby. We will see.



RECON Schedule ahead:

WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT SUN JUN 24 2012
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 25/1100Z TO 26/1100Z JUN 2012
TCPOD NUMBER.....12-037

I. ATLANTIC REQUIREMENTS
1. TROPICAL STORM DEBBY
FLIGHT ONE -- TEAL 70 --
A. 26/0000Z, 0600Z
B. AFXXX 0504A DEBBY
C. 25/2245Z
D. 28.5N 86.2W
E. 25/2315Z TO 26/0600Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 71 --
A. 26/1200,1800Z
B. AFXXX 0604A DEBBY
C. 25/1045Z
D. 28.7N 87.0W
E. 26/1115Z TO 26/1800Z
F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY:
A. CONTINUE 6-HRLY FIXES.
B. A P-3 TAIL DOPPLER RADAR MISSION AT 26/2000Z

[David Paul]

That's a significant track change. Prolly see more changes over coming days. One thing that popped into my mind is.. on that track, a cat one hurricane... I wonder how those levees are doing in N.O. these days?

[gocuse22]

Sigh, NAM keeps it towards Florida. Meanwhile we're back in a >100 degree oven.

NAM might be the worst model to use for the tropics...

[gocuse22]

GFS runs in about 5 minutes.

[weatherguy425]

Sigh, NAM keeps it towards Florida. Meanwhile we're back in a >100 degree oven.

NAM might be the worst model to use for the tropics...

Definitely is, but a model none the less. (at least so far today) consensus appears to be favoring an Eastern GOM threat, guess we'll see.

[gocuse22]

Sigh, NAM keeps it towards Florida. Meanwhile we're back in a >100 degree oven.

NAM might be the worst model to use for the tropics...

Definitely is, but a model none the less. (at least so far today) consensus appears to be favoring an Eastern GOM threat, guess we'll see.

Main thing we have to watch for is if/when Debby makes its west turn

[gocuse22]

GFS isnt showing a pressure for Debby and drops it down to 995MB tomorrow when its already at 994 right now..

Well im off the the Indians-Astros game. By the time i get back im sure a lot will change..

[Scott747]

lol. I'm about to give up.

Almost looks like it's doing some type of pseudo reverse decoupling with the mlc and llc switching places.

[Portastorm]

GFS isnt showing a pressure for Debby and drops it down to 995MB tomorrow when its already at 994 right now..

Well im off the the Indians-Astros game. By the time i get back im sure a lot will change..

(off topic) Hope you have better luck than I did yesterday ... that is, if you're a Tribe fan like I am. I watched the Astros administer a butt-kicking to my team. Nevertheless, Minute Maid air conditioning/concessions/great Houston fans made it a fun day.

[Portastorm]

lol. I'm about to give up.

Almost looks like it's doing some type of pseudo reverse decoupling with the mlc and llc switching places.

Latest satellite view looked to me almost like the center was re-locating further west. Do you see that too?

[Scott747]

lol. I'm about to give up.

Almost looks like it's doing some type of pseudo reverse decoupling with the mlc and llc switching places.

Latest satellite view looked to me almost like the center was re-locating further west. Do you see that too?

For a spell it looked like there was a mlc trying to get going to the SW in the vicinity of the previous track.

It's a hot mess right now. I was joking on American that the NHC might issue a special advisory that landfall occurred six hours ago.

At the rate it's going it might be inland by late tonight.

[srainhoutx]

lol. I'm about to give up.

Almost looks like it's doing some type of pseudo reverse decoupling with the mlc and llc switching places.

Latest satellite view looked to me almost like the center was re-locating further west. Do you see that too?

There is a meso vort rotating NE around the elongated WSW-ENE broad low pressure via HiRes Imagery. I counted at least 4-6 of those meso vorts yesterday rotating around. No consolidation what so ever. The broad area of low pressure is drift in a W to WNW fashion. What I find interesting is that some of the computer models suggested this low level 850mb and upper level 500mb decoupling and it was dismissed as convective feed back when the GFS had everything heading NE while other guidance had everything heading W to WSW. Welcome to an early Gulf season sheared slopgyre...lol

[jasons2k]

It looks like a giant, disorganized mess to me. I think we need to be cautious with this one. It's not so clear cut this whole thing will sling NE and out to sea (though it could). It's quite possible the MLC splitting to the NE could die off, and we could get redevelopment to the SW. It's still a crapshoot on if it eventually gets pushed west at some point.