ATL HANNA: Extratropical - Discussion

[AtlanticWind]

Hanna on the NRL site

[robbielyn]

nhc not concerned d/t proximity of land

[expat2carib]

I expected it to be red at eleven and now NHC changed it to yellow. WHY? WHAT?

[Praxus]

expatcarib - the yellow system is the campeche one, not TD8 / Hanna

Thread is here

viewtopic.php?f=31&t=102776

[HURAKAN]

Please, this thread is about TD #8 / "Hanna," stop talking about the disturbance in the BOC.

[AtlanticWind]

Gustav has a baby sister

[mascpa]

Not sure but I believe he was referring to the system in the Bay of Campeche as having been given a yellow designation.

[expat2carib]

Please, this thread is about TD #8 / "Hanna," stop talking about the disturbance in the BOC.

Sorry! My amateur mistake.

[O Town]

Please, this thread is about TD #8 / "Hanna," stop talking about the disturbance in the BOC.

BOC thread.....
viewtopic.php?f=31&t=102776

[Just Joshing You]

NHC say the HWRF and GFDL take this to be an intense cane. Am I correct in saying that the HWRF and GFDL are the 'good' models? I.E The ones they use most frequently in forecasting?

[umguy]

Wow what a morning! And hello campeche system...

I know the NHC weren't really mentioning the Campeche system, but it looks good.

\

I thought the same thing

[Ground_Zero_92]

I'm not sure about the HWRF, but the GFDL is one of the preferred models the the NHC uses. With that said, these models are historically better with track and not intensity. Verifiable intensity forecasting is still an area that is lacking with all models.

NHC say the HWRF and GFDL take this to be an intense cane. Am I correct in saying that the HWRF and GFDL are the 'good' models? I.E The ones they use most frequently in forecasting?

[THead]

Jeez, in that IR shot Hanna already looks like a hurricane to my amatuer eyes!


She looks to already have some heavy bands at the ready to feed the beast!

[RL3AO]

Jeez, in that IR shot Hanna already looks like a hurricane to my amatuer eyes!


She looks to already have some heavy bands at the ready to feed the beast!

But when you look at visibles...

[CrazyC83]

Looks to be about 45-50 kt from my view.

[seaswing]

So what would be the chances of TD8 or Hanna and Gustauv each hitting the CONUS at the same time or within a 24 hour period of each other?

[bob rulz]

So what would be the chances of TD8 or Hanna and Gustauv each hitting the CONUS at the same time or within a 24 hour period of each other?

Hanna would have to go at unrealistic speeds or Gustav would have to essentially stop moving for a couple of days for that to happen.

[Vortex]

Hanna has all the makings of becoming a strong cyclone in 3-5 days. Currently, the LLC is somewhat exposed but over the next day or so the westerly shear will relax and Hanna is poised to become a hurricane. My concern is when she reaches 24-26N and around 70W ridging to the north will build in and she will turn w or even wsw. At that point she will have very favorable upper-air conditions to continue to strengthen..

[Bocadude85]

I do think this is going to dive to the wsw at some point but I am not sold on this making it all the way to the coast just yet

[gatorcane]

its officially Hanna:

000
WTNT33 KNHC 281441
TCPAT3
BULLETIN
TROPICAL STORM HANNA ADVISORY NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082008
1100 AM AST THU AUG 28 2008

...HANNA BECOMES EIGHTH TROPICAL STORM OF THE SEASON...

AT 1100 AM AST...1500Z...THE CENTER OF TROPICAL STORM HANNA WAS
LOCATED NEAR LATITUDE 20.5 NORTH...LONGITUDE 59.2 WEST OR ABOUT 305
MILES...490 KM...NORTHEAST OF THE NORTHERN LEEWARD ISLANDS.

HANNA IS MOVING TOWARD THE WEST-NORTHWEST NEAR 12 MPH...19 KM/HR.
A TURN TOWARD THE NORTHWEST IS EXPECTED LATER TODAY. ON THE
FORECAST TRACK...HANNA WILL MOVE AWAY FROM THE NORTHERN LEEWARD
ISLANDS AND BE CENTERED WELL TO THE NORTHEAST OF THE BAHAMAS DURING
THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS ARE NEAR 40 MPH...65 KM/HR...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 50 MILES...85 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB...29.59 INCHES.

HANNA COULD PRODUCE RAINFALL ACCUMULATIONS OF 1 TO 2 INCHES...WITH
POSSIBLE MAXIMUM AMOUNTS OF 4 INCHES ACROSS PORTIONS OF THE LEEWARD
ISLANDS.

REPEATING THE 1100 AM AST POSITION...20.5 N...59.2 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 12 MPH. MAXIMUM SUSTAINED WINDS...40
MPH. MINIMUM CENTRAL PRESSURE...1002 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 PM AST.

$$
FORECASTER RHOME



000
WTNT43 KNHC 281442
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082008
1100 AM EDT THU AUG 28 2008

SATELLITE IMAGERY INDICATES THAT THE CLOUD PATTERN ASSOCIATED WITH
THE CYCLONE HAS IMPROVED DURING THE LAST 6 HOURS AND LATEST DVORAK
INTENSITY ESTIMATES INDICATE WINDS ARE NOW NEAR 35 KT. BASED ON
THIS INFORMATION...THE DEPRESSION IS UPGRADED TO TROPICAL STORM
HANNA. VISIBLE IMAGERY SHOWS THAT HANNA'S LOW LEVEL CIRCULATION IS
PARTIALLY EXPOSED ON THE WESTERN EDGE OF THE DEEP CONVECTION
INDICATING WESTERLY SHEAR...ASSOCIATED WITH AN UPPER-LEVEL LOW TO
THE WEST IS IMPACTING THE SYSTEM. SINCE THE OCEAN IS PLENTY
WARM...THE INTENSITY FORECAST IS PRIMARILY A FUNCTION OF HOW HANNA
INTERACTS WITH THE UPPER-LEVEL LOW. GLOBAL MODELS FORECAST THE
UPPER-LEVEL LOW TO MOVE WEST-SOUTHWEST OVER THE NEXT SEVERAL DAYS
PLACING HANNA IN A LOW VERTICAL SHEAR ENVIRONMENT WITH AMPLE
DIVERGENT FLOW ALOFT. SUCH AN ENVIRONMENT WOULD FAVOR
INTENSIFICATION SHOULD IT MATERIALIZE. HOWEVER...AS IS OFTEN THE
CASE...THERE IS A FINE LINE BETWEEN A FAVORABLE AND UNFAVORABLE
ENVIRONMENT FOR STRENGTHENING. THE OFFICIAL FORECAST ASSUMES THERE
WILL BE SUFFICIENT SPACING BETWEEN THE UPPER-LEVEL LOW AND HANNA TO
PROMOTE STRENGTHENING. BY DAY 5...UPPER-LEVEL OUTFLOW FROM GUSTAV
COULD IMPART NORTHERLY SHEAR OVER HANNA POSSIBLY AFFECTING THE
INTENSITY.

HANNA HAS BEEN MOVING TOWARD THE WEST-NORTHWEST...OR 300/10...DURING
THE LAST 6 HOURS. HOWEVER...A MOTION TOWARD THE NORTHWEST IS
EXPECTED OVER THE NEXT 2-3 DAYS AS HANNA MOVES AROUND THE
SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE. THEREAFTER...THE
TRACK BECOMES MUCH LESS CERTAIN AS IT REMAINS TO BE SEEN HOW HANNA
WILL INTERACT WITH A MID-LATITUDE TROUGH FORECAST TO MOVE
OFF THE U.S. EAST COAST. MOST OF THE DYNAMICAL MODELS SHOW HANNA
BEING LEFT BEHIND IN AN AREA OF WEAK STEERING. HOWEVER...THE
TRADITIONALLY GOOD PERFORMING GFS FORECASTS HANNA TO TURN
NORTHEASTWARD AT DAYS 4 AND 5. THE OFFICIAL FORECAST ASSUMES THE
FORMER OF THOSE SCENARIOS AND SHOWS A SLOW WESTWARD TRACK.

FORECAST POSITIONS AND MAX WINDS

INITIAL 28/1500Z 20.5N 59.2W 35 KT
12HR VT 29/0000Z 21.4N 60.4W 40 KT
24HR VT 29/1200Z 22.8N 61.9W 45 KT
36HR VT 30/0000Z 24.4N 63.7W 55 KT
48HR VT 30/1200Z 25.7N 65.6W 60 KT
72HR VT 31/1200Z 27.0N 68.5W 70 KT
96HR VT 01/1200Z 27.5N 70.0W 75 KT
120HR VT 02/1200Z 27.5N 71.5W 70 KT

$$
FORECASTER RHOME