Tropical depression 6.

[skids]

http://skeetobiteweather.com/

THE AREA OF LOW PRESSURE MIDWAY BETWEEN AFRICA AND THE LESSER
ANTILLES HAS A BROAD CLOSED CIRCULATION AND ENOUGH CONVECTIVE
ORGANIZATION TO GARNER DVORAK CLASSIFICATION OF T2.0 FROM TAFB AND
SAB. CONSEQUENTLY...ADVISORIES ARE INITIATED ON A TROPICAL
DEPRESSION. BUOY 41026 REPORTED 32 KT WINDS LATE THIS
MORNING...ALTHOUGH THEY HAVE SINCE DECREASED...AND THIS IS THE
BASIS FOR THE ADVISORY INTENSITY OF 30 KT.

THE CENTER OF CIRCULATION IS DIFFICULT TO SEE...AND THERE MAY BE
MULTIPLE SWIRLS ROTATING AROUND A COMMON CENTER. THE INITIAL
MOTION IS THEREFORE UNCERTAIN BUT ESTIMATED TO BE 305/12. A STRONG
MID-LATITUDE TROUGH IS NORTHWEST OF THE DEPRESSION...AND THIS
WEAKNESS SHOULD ALLOW THE PRESENT MOTION TO CONTINUE...WITH SOME
DECREASE IN FORWARD SPEED...FOR THE NEXT DAY OR TWO. AFTER
THAT...GLOBAL MODELS FORECAST THAT THE TROUGH WILL LIFT OUT...WITH
HIGH PRESSURE BUILDING EASTWARD TO THE NORTH OF THE CYCLONE. THIS
PATTERN IS EXPECTED TO BEND THE TRACK BACK TO THE LEFT TOWARDS THE
END OF THE FORECAST PERIOD. TRACK GUIDANCE MODELS ARE IN GENERAL
AGREEMENT ON THIS SCENARIO...ALTHOUGH WITH GREAT DIFFERENCES IN
FORWARD SPEED. THE OFFICIAL FORECAST LEANS TOWARD THE FASTER
MOTION OF THE GFDL AND BAM MODELS...WITH THE UKMET AND ECMWF BEING
CONSIDERABLY SLOWER. WITH CONVECTION OVER A BROAD AREA AND THE
PRESENCE OF MULTIPLE SWIRLS...IT IS NOT CLEAR EXACTLY WHERE THE
CENTER WILL CONSOLIDATE. THERE IS SOME CHANCE THE CENTER COULD
CONSOLIDATE TO THE NORTH OF THE CURRENT TRACK AND BE MORE
INFLUENCED BY THE CENTRAL ATLANTIC TROUGH.

THERE IS SOME SOUTHWESTERLY SHEAR TO THE NORTHWEST OF THE
CYCLONE...AND THIS COULD LIMIT DEVELOPMENT OVER THE NEXT COUPLE OF
DAYS. AFTER THE TROUGH LIFTS OUT...THE ENVIRONMENT SHOULD BECOME
MORE FAVORABLE FOR DEVELOPMENT AND BOTH THE SHIPS AND GFDL GUIDANCE
BRING THE DEPRESSION TO HURRICANE STRENGTH. THE OFFICIAL FORECAST
IS A BLEND OF THE NUMBERS FROM THESE TWO MODELS.

http://www.nhc.noaa.gov/text/refresh/MIATCDAT1+shtml/032030.shtml

[jpak]

1. go away

:mad:

[skids]

2. Update. Check out the gulf stream and ITCZ.

They say their models are having a rough time of it dealing with this huge "trough." Right now the gulf stream water vapor trail seems to be crossing the eastern US, being sucked up north to 40-45N by a really strong fully coupled system that is apparently causing tornados west of the great lakes, and then dropping southwards to 20N or so, then cruising back up and taking practically all of the water vapor from the ITCZ with it up to Europe... a complete U-turn -- stuff coming off West Africa is getting sucked up like a vacuum cleaner.



Insane windshear. One could hope it kills TD6. It probably won't kill the so-far unnumbered system right to the east of TD6. It would be nice if this was dumping snowfall on the ice caps, but I wouldn't bet on it. In any case that's some weird stuff going on, in my totally not an expert by any stretch opinion.

WHILE THERE HAS BEEN SOME INCREASE IN CONVECTION OVERNIGHT...THE
OVERALL ORGANIZATION REMAINS POOR. THE DEPRESSION CONSISTS OF A
LARGE CIRCULATION WITH CONVECTION PRIMARILY FOCUSED NEAR THE OUTER
PERIPHERY. ACCORDINGLY...THE INITIAL INTENSITY WILL REMAIN AT 30
KT. THE DEPRESSION IS STILL FIGHTING SOUTHWESTERLY SHEAR ASSOCIATED
WITH AN UNUSUALLY HIGH-AMPLITUDE TROUGH OVER THE CENTRAL ATLANTIC.
GLOBAL MODELS INDICATE THAT THE TROUGH...AND ASSOCIATED VERTICAL
SHEAR...WILL PERSIST FOR ANOTHER 2 DAYS. GIVEN THIS AND THE
PRESENT LACK OF ORGANIZATION...SIGNIFICANT STRENGTHENING IS NOT
ANTICIPATED IN THE SHORT-TERM. BEYOND 48 HOURS...GLOBAL MODELS
FORECAST THE UPPER-TROPOSPHERIC TROUGH TO FRACTURE FORMING AN UPPER
LOW TO THE WEST OF THE CYCLONE. THIS PATTERN...IF VERIFIED...WOULD
RESULT IN A MORE FAVORABLE ENVIRONMENT FOR STRENGTHENING.
HOWEVER...THE DEPRESSION HAS A TOUGH ROAD IN THE INTERIM...AND WILL
NEED TO SURVIVE THE NEXT COUPLE OF DAYS TO REACH THIS IMPROVED
ENVIRONMENT. THIS COMPLEX EVOLUTION MEANS GREATER THAN USUAL
UNCERTAINTY...AND THE OFFICIAL FORECAST IS AT THE LOWER END OF THE
AVAILABLE GUIDANCE.

LOCATING THE CENTER OF THE DEPRESSION IS A DIFFICULT TASK. SATELLITE
IMAGERY SUGGEST THAT THERE ARE SEVERAL SMALLER SCALE TRANSIENT
CENTERS EMBEDDED WITHIN A LARGER CIRCULATION. THE ADVISORY POSITION
IS BASED ON THE MEAN CENTER OF THE LARGE CIRCULATION YIELDING AN
INITIAL MOTION OF 300/11. THIS GENERAL MOTION IS EXPECTED TO
CONTINUE OVER THE NEXT 24-36 HOURS AS THE CYCLONE MOVES INTO A
WEAKNESS IN THE MID-LEVEL SUBTROPICAL RIDGE. THEREAFTER...A
MID-LEVEL ANTICYCLONE OVER THE WESTERN ATLANTIC IS FORECAST TO
SHIFT EASTWARD TO THE NORTH OF THE CYCLONE RESULTING IN SOME
INCREASE IN FORWARD SPEED. BY THE END OF THE FORECAST...THE
CYCLONE IS EXPECTED TO TURN TOWARDS THE NORTHWEST AS IT REACHES THE
WESTERN ANTICYCLONE. THE OFFICIAL FORECAST IS
CLOSE TO THE DYNAMICAL MODEL CONSENSUS...AND THE PREVIOUS ADVISORY.

http://www.nhc.noaa.gov/text/refresh/MIATCDAT1+shtml/050827.shtml

[phantom power]

3. What does ITCZ stand for?

[jpak]

4. Inter-Tropical Convergence Zone

It's a broad area of low pressure where the trade winds converge (at the solar Equator) that forms the ascending limb of the Hadley cell.