[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131105
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE MAR 13 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0900 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA INTO THE E TROPICAL
ATLC NEAR 8N13W TO 5N16W WHERE THE ITCZ AXIS CONTINUES ALONG
2N23W THEN S OF THE EQUATOR NEAR 29W INTO SOUTH AMERICA NEAR
3S44W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ARE FROM 1N-5N BETWEEN 5W-22W AND FROM 5N TO S OF THE EQUATOR
BETWEEN 22W-45W.

...DISCUSSION...

GULF OF MEXICO...
THE STRONG UPPER LOW HAS MOVED ACROSS THE GREAT LAKES INTO
CANADA WITH A SHORTWAVE UPPER TROUGH ACROSS THE LOWER
MISSISSIPPI VALLEY TO THE N GULF COAST GENERATING SCATTERED
SHOWERS INLAND AND ALONG THE IMMEDIATE GULF COAST OF ALABAMA AND
THE FLORIDA PANHANDLE. A SURFACE TROUGH REMAINS OVER THE BAY OF
CAMPECHE AT 13/0900 UTC EXTENDING FROM 23N91W ALONG 20N93W TO
INLAND OVER S MEXICO NEAR 18N93W WITH ISOLATED SHOWERS WITHIN
120 NM EITHER SIDE OF THE TROUGH AXIS. THE GULF IS DOMINATED BY
NEAR ZONAL WESTERLY FLOW ALOFT. A SURFACE RIDGE EXTENDS FROM THE
W ATLC AND A 1031 MB HIGH N OF BERMUDA TO ALONG THE N GULF COAST
COVERING THE GULF OF MEXICO. S TO SE RETURN COVERS THE GULF N OF
25N WITH MORE EASTERLY FLOW S OF 25N. THIS SURFACE FLOW
CONVERGING WITH THE FLOW ALOFT IS PRODUCING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS OVER THE SE GULF S OF 25N E OF 88W
LEAVING THE REMAINDER OF THE GULF UNDER MOSTLY CLEAR SKIES THIS
MORNING. SURFACE RIDGE WILL PREVAIL THROUGH SAT.

CARIBBEAN SEA...
WEAK UPPER TROUGH EXTENDS FROM THE W ATLC THROUGH THE WINDWARD
PASSAGE TO OVER JAMAICA AMPLIFYING AN UPPER RIDGE AXIS THAT
EXTENDS FROM NEAR THE CAYMAN ISLANDS ACROSS CENTRAL CUBA INTO
THE W ATLC. A BROAD UPPER RIDGE OVER THE TROPICAL ATLC DOMINATES
THE REMAINDER OF THE CARIBBEAN. MODERATE/STRONG SUBSIDENCE AND
DRY STABLE AIR PREVAIL ACROSS THE CARIBBEAN WITH THE EXCEPTION
OF THE FAR SE CARIBBEAN. REMNANT LOW LEVEL ISOLATED SHOWERS DOT
THE AREA FROM 16N-20N BETWEEN 72W-82W INCLUDING PORTIONS OF
HAITI AND JAMAICA. THE BROAD UPPER RIDGE IS DRAWING MOISTURE
ALOFT AND IS GENERATING SOME ISOLATED SHOWERS OVER THE WINDWARD
ISLANDS. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN UNDER
MOSTLY CLEAR SKIES THIS MORNING. THE TIGHT PRESSURE GRADIENT IS
PRODUCING FRESH TO STRONG NE TO E TRADE WINDS ACROSS THE BASIN.
LITTLE CHANGE IS EXPECTED THROUGH SAT.

ATLANTIC OCEAN...
AN UPPER RIDGE EXTENDS FROM THE CARIBBEAN ACROSS CENTRAL CUBA TO
BEYOND 32N71W IN THE W ATLC. A SURFACE RIDGE COVERS THE W INTO
THE CENTRAL ATLC W OF 50W ANCHORED BY A 1031 MB HIGH JUST N OF
BERMUDA. A BROAD UPPER TROUGH COVERS THE REMAINDER OF THE W ATLC
INTO THE CENTRAL ATLC THROUGH WITH THE MEAN AXIS THROUGH 32N56W
ALONG 24N66W NARROWING AS IT ENTERS THE CARIBBEAN OVER CENTRAL
CUBA SUPPORTING A COLD FRONT THAT ENTERS THE CENTRAL ATLC NEAR
32N43W ALONG 28N45W TO 25N48W. SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS ARE WITHIN 120 NM E OF THE FRONT. BROAD
UPPER RIDGE COVERS THE TROPICAL ATLC S OF 25N E OF 60W WITH A
NARROW RIDGE AXIS EXTENDING FROM 25N31W TO BEYOND 32N27W. A
SURFACE RIDGE DOMINATES THE E ATLC ANCHORED BY A 1027 MB HIGH
JUST S OF THE AZORES. THE FIRST VISIBLE SATELLITE IMAGES SHOW
THE AREA OF AFRICAN DUST COVERING THE E TROPICAL ATLC FROM THE
ITCZ TO 27N E OF 42W AND IS BECOMING DIFFUSED. W ATLC SURFACE
RIDGE WILL REMAIN THROUGH WED. THE TAIL END OF WEAK COLD FRONT
EXTENDS JUST TO THE N PERIPHERY OF THE W ATLC THU AND NEW BUT
WEAKER SURFACE RIDGE BUILDS ALONG 31N THROUGH SAT.

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

$$
PAW




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