[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 082349
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU MAR 08 2012

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS SW FROM THE AFRICAN COAST AT 08N13W
TO 03N16W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ
WHICH CONTINUES WESTWARD ALONG 02N TO 40W THEN TURNS SW TO THE
EQUATOR AT THE COAST OF S AMERICA. LOCALLY BROKEN LOW AND MID
LEVEL CLOUDS...WITH EMBEDDED SHOWERS...ARE OBSERVED WITHIN 120
NM EITHER SIDE OF A LINE FROM 02N24W TO 06N48W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER ANTICYCLONE IS QUASI STATIONARY OVER THE E PACIFIC NEAR
13N97W...WITH AN UPPER RIDGE EXTENDING NE ACROSS CENTRAL MEXICO
AND THE BAY OF CAMPECHE TO THE WESTERN FLORIDA PANHANDLE...AND
CONTINUING NE ALONG THE EASTERN SEABOARD OF THE CONUS. LOOKING
UPSTREAM...A DEEP LAYERED SHORTWAVE TROUGH DISSECTS THE CENTRAL
CONUS ENHANCING CONSIDERABLE CONVECTION WITH SOME OF THE
RESULTANT UPPER DEBRIS MOISTURE...MOSTLY FROM PREVIOUS
CONVECTION OVER CENTRAL TEXAS...NOW SPILLING E ACROSS THE UPPER
RIDGE OVER THE NW GULF OF MEXICO. THIN BROKEN CIRRIFORM CLOUDS
ARE RACING NE ACROSS CENTRAL OLD MEXICO AND ACROSS THE WESTERN
BAY OF CAMPECHE. OTHERWISE...THE UPPER LEVELS APPEAR DRY ACROSS
THE GULF OF MEXICO. AT THE LOW LEVELS A STATIONARY RIDGE
DISSECTS THE GULF FROM NW FLORIDA TO THE BAY OF CAMPECHE.
SCATTERED LOW LEVEL CLOUDS...WITH ONLY A FEW SHOWERS...CONTINUE
TO MOVE N OVER THE E CENTRAL GULF WATERS. A SHRINKING AREA OF
LOCALLY OVERCAST LOW LEVEL CLOUDS...AND PATCHY FOG REDUCING
VISIBILITIES BELOW 3 SM...IS MOVING N IN THE 15 TO 20 KT LOW
LEVEL SOUTHERLY FLOW OVER THE NW GULF...EXTENDING INLAND OVER
THE NE TEXAS AND SW LOUISIANA COASTAL PLAINS. THE SURFACE RIDGE
IS EXPECTED TO SHIFT EASTWARD TONIGHT ALLOWING A COLD FRONT TO
MOVE INTO THE NW WATERS ON FRI ACCOMPANIED BRIEFLY BY NORTHERLY
WINDS TO 30 KT. THE FRONT STALLS LATE FRI NIGHT INTO SAT WITH
THE NORTHERLY WINDS DIMINISHING TO 20 KT.

THE CARIBBEAN SEA...
AN UPPER TROUGH CONTINUES OVER THE CENTRAL CARIBBEAN WITH ITS
MEAN AXIS EXTENDING FROM THE WINDWARD PASSAGE TO THE NW COAST OF
COLOMBIA...AND IS ACCOMPANIED BY VERY DRY AIR ALOFT. LOCALLY
BROKEN LOW LEVEL CLOUDS...WITH BRIEF SHOWERS...ARE RACING
WESTWARD OVER THE CARIBBEAN TO THE N OF 15N AND DOWNSTREAM OF
THE LARGER WINDWARD ISLANDS. THE EASTERLY TRADES ARE ENHANCED
ALONG THE NW COAST OF COLOMBIA WITH A 30 TO 35 KT GALE WARNING
IN EFFECT FROM 11N TO 15N BETWEEN 73W AND 79W THIS AFTERNOON...
BUT THE EFFECTED AREA IS FORECAST TO SHRINK FROM 11N TO 13N
BETWEEN 73W AND 77W ON FRI THEN DIMINISH BELOW GALE FRIDAY
EVENING. THE ASSOCIATED SEAS TO 18 FT TONIGHT WILL SUBSIDE TO
ABOUT A 16 FT MAXIMUM ON FRI...AND FURTHER SUBSIDE TO 14 FT ON
FRI NIGHT.

THE ATLANTIC OCEAN...
AN UPPER RIDGE IS ORIENTATED SW TO NE ALONG THE EASTERN SEABOARD
OF THE CONUS WITH DENSE UPPER MOISTURE OBSERVED W OF THE RIDGE
AXIS...AND WILL LIKELY SHIFT E OVER THE COASTAL WATERS OF
GEORGIA AND FLORIDA TONIGHT. THE NORTHERN SEGMENT OF A DEEP
LAYERED TROUGH MOVING INTO THE N CENTRAL ATLANTIC IS MERGING
WITH THE REMNANTS OF AN UPPER CYCLONE THAT PREVIOUSLY CUT OFF
OVER THE N CENTRAL PORTION OF THE DISCUSSION AREA. THE SOUTHERN
SEGMENT OF THE UPPER TROUGH EXTENDS FROM NEAR BERMUDA TO THE
WINDWARD PASSAGE. UPPER DIFFLUENCE IS ENHANCING CONVECTION ALONG
A DISSIPATING LOW LEVEL SHEAR AXIS THAT EXTENDS FROM 31N35W TO
24N60W TO THE CENTRAL BAHAMAS...WITH SOME EVIDENCE OF THE SHEAR
AXIS CONTINUING NW ACROSS SOUTHERN FLORIDA WHERE CONVECTION HAS
PERSISTED FOR NEARLY 24 HOURS. UPPER MOISTURE IS SWINGING
CYCLONICALLY THROUGH THE TROUGH NEAR 24N70W. A DEEP TROPICAL
UPPER ANTICYCLONE IS NEAR 04N27W WITH A RIDGE EXTENDING N TO A
CREST AT 32N60W. A LARGE AREA OF OVERCAST MULTILAYERED CLOUDS IS
OBSERVED UNDER THE RIDGE CREST WITHIN 120 NM OF 28N60W WITH
LIGHTNING DATA DETECTING EMBEDDED TSTMS NEAR 26N58W. UPPER
DEBRIS MOISTURE FROM THIS CLOUDINESS AND CONVECTION IS ADVECTED
E IN A 200 NM WIDE BAND FROM 27N50W TO 28N38W TO WELL BEYOND
32N32N.

AN UPPER TROUGH IS DIGGING S OVER NW AFRICA WITH ITS MEAN AXIS
EXTENDING FROM 31N07W TO A BASE NEAR 19N01E AT THE MOMENT. A
SECOND RIDGE EXTENDS NE FROM THE DEEP TROPICAL ANTICYCLONE AT
04N27W TO A CREST AT 28N20W. A VERY DENSE MOISTURE PLUME...
ORIGINATING OVER S AMERICA...IS STREAMING E ACROSS THE
DISCUSSION AREA S OF 15N BETWEEN 35W AND 60W...FANNING OUT UNDER
THE UPPER RIDGE OVER THE AREA FROM 10N TO 27N BETWEEN 30W AND
10W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
NELSON





This weather bulletin was brought to you by:
www.nashvilleweather.net