[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071804
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUL 07 2011

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1530 UTC.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 12N45W TO 02N48W AND IS
MOVING W AT 10-15 KT. SCATTERED MODERATE CONVECTION IS PRIMARILY
NOTED TO THE W OF THE TROPICAL WAVE TO 56W AND N OF THE ITCZ.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 20N58W TO 13N64W AND IS
MOVING W-NW AT 10-15 KT. SCATTERED MODERATE WITH ISOLATED STRONG
CONVECTION COVERS THE CARIBBEAN SEA AND THE ATLANTIC OCEAN FROM
15N TO 19N BETWEEN THIS WAVE AND A SURFACE TROUGH THAT LIES
ALONG 70W S OF 16N AS WELL AS E OF THE WAVE TO 56W FROM 16N TO
20N.

A TROPICAL WAVE EXTENDS FROM 24N91W INTO SOUTHEASTERN MEXICO
NEAR 17N92W AND IS MOVING W AT 5-10 KT. DEEP CONVECTION HAS
DIMINISHED NEAR THIS WAVE.

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

A MONSOON TROUGH PASSES THROUGH THE PRIME MERIDIAN ALONG
22N...CURVING TO 12N16W 8N30W. THE ITCZ CONTINUES FROM 08N30W TO
08N44W...REACHING COASTAL BORDER OF BRAZIL AND FRENCH GUIANA
NEAR 04N54W. A MONSOON TROUGH ALSO LIES ALONG 11N BETWEEN 72W
AND NE COSTA RICA AND THEN EXTENDS NORTHWARD INTO EL SALVADOR.
SCATTERED MODERATE CONVECTION LIES WITHIN 90 NM N OF THE MONSOON
TROUGH BETWEEN 75W AND NORTHERN COSTA RICA.

...DISCUSSION...

THE GULF OF MEXICO...

A STRONG UPPER LEVEL LOW LIES NEAR 28N89W. CYCLONIC FLOW ALOFT
COVERS THE ENTIRE GULF OF MEXICO. WATER VAPOR IMAGERY INDICATES
DRY AIR ALOFT LIES OVER MUCH OF THE GULF W OF 86W WITH SOME HIGH
LEVEL MOISTURE BEGINNING TO ADVECT EASTWARD FROM THE NEWLY
FORMED TROPICAL DEPRESSION THREE-E IN THE EASTERN PACIFIC INTO
THE FAR SW GULF OF MEXICO. A TROPICAL WAVE EXTENDS FROM 24N91W
INTO SOUTHEASTERN MEXICO NEAR 17N92W. DEEP CONVECTION HAS
DIMINISHED NEAR THIS WAVE UNDER THE DRY AIR ALOFT AND STRONG
WESTERLY SHEAR. A SURFACE LOW LIES IN THE SE GULF NEAR 25N84W
AND EXTENDS A TROUGH NORTHEASTWARD INTO FLORIDA NEAR CAPE CORAL
TO DAYTONA BEACH. SCATTERED MODERATE WITH ISOLATED STRONG
CONVECTION ASSOCIATED WITH THIS SYSTEM LIES OVER MUCH OF THE
AREA FROM 24N TO 29N E OF 86W AS WELL AS SW OF THE SYSTEM INTO
THE YUCATAN CHANNEL. THIS LOW IS FORECAST TO SLOWLY MOVE NW
TOWARD THE NORTH CENTRAL GULF OVER THE NEXT TWO DAYS.
ALOFT...THE UPPER LOW WILL BE FORCED WESTWARD AS THE UPPER RIDGE
THAT CURRENTLY LIES JUST S OF THE GULF LIFTS NORTHEASTWARD AND
CUTS OFF AN ANTICYCLONE OVER FLORIDA.


THE CARIBBEAN SEA...

THE SOUTHERN END OF AN UPPER LEVEL TROUGH PASSES THROUGH THE
ATLANTIC OCEAN NEAR 32N50W AND REACHES WESTERN PUERTO RICO
BEFORE TURNING SOUTHWARD TO NEAR 12N70W. A TROPICAL WAVE LIES TO
THE E OF THE TROUGH FROM 20N58W TO 13N64W. THE CONVECTION NOTED
WITH THIS WAVE IS DESCRIBED ABOVE. IT PRIMARILY LIES BETWEEN THE
TROPICAL WAVE AND A SURFACE TROUGH ALONG 70W S OF 16N WITH MUCH
OF THE NE CARIBBEAN CURRENTLY RECEIVING MODERATE TO HEAVY RAIN.
THE TROPICAL WAVE WILL CONTINUE WESTWARD THROUGH THE GREATER
ANTILLES OVER THE NEXT FEW DAYS AND BRING CONTINUED RAINFALL
WITH IT. FRESH TO STRONG EASTERLY WINDS OVER MUCH OF THE CENTRAL
CARIBBEAN ARE BEING FORCED BY A STRONG PRES GRADIENT BETWEEN THE
SUBTROPICAL HIGH AND LOWER PRES OVER THE SW CARIBBEAN WHERE A
MONSOON TROUGH LIES OVER THE REGION ALONG 11N. SHOWERS AND
THUNDERSTORMS ARE CONTAINED TO WITHIN 90 NM N OF THE MONSOON
TROUGH AXIS. DRIER AIR ALOFT LIMITS DEEP CONVECTION OVER MUCH OF
THE REMAINDER OF THE CARIBBEAN S OF 17N AND W OF 73W. AN UPPER
RIDGE LIES OVER THE NW CARIBBEAN FROM THE EASTERN YUCATAN
PENINSULA TO CENTRAL CUBA. NORTHERLY WINDS ALOFT ARE
TRANSPORTING UPPER MOISTURE ASSOCIATED WITH THE LOW PRES SYSTEM
IN THE SE GULF OF MEXICO SOUTHWARD INTO THE NW CARIBBEAN TO 17N.
OVERCAST SKIES ARE FOUND OVER MUCH OF THIS AREA WITH SOME
SHOWERS AND THUNDERSTORMS NOTED IN THE YUCATAN CHANNEL AND
WESTERN CUBA. THE UPPER RIDGE IS FORECAST TO LIFT NORTHWARD AND
CARRY THE BEST CHANCE OF PRECIPITATION OUT OF THE REGION LATE
TONIGHT.

THE ATLANTIC OCEAN...

THE UPPER LEVEL RIDGE THAT PASSES THROUGH THE NW CARIBBEAN SEA
EMERGES INTO THE STRAITS OF FLORIDA AND EXTENDS NORTHEASTWARD TO
32N74W. THE DIFFLUENCE ALOFT INDUCED BY THIS RIDGE AXIS IS
ENHANCING CONVECTION PRIMARILY W OF 77W...INCLUDING THE WESTERN
BAHAMAS AND OVER THE SOUTHERN FLORIDA PENINSULA. THIS RIDGE IS
EXPECTED TO CUT OFF AN ANTICYCLONE THAT WILL PASS N THROUGH THE
FLORIDA PENINSULA OVER THE NEXT FEW DAYS. SHOWERS AND
THUNDERSTORMS WILL PERSIST OVER THE AREA AND EXPAND INTO
NORTHEAST FLORIDA AND THE OFFSHORE WATERS. AN UPPER LEVEL TROUGH
PASSES THROUGH 32N50W AND REACHES WESTERN PUERTO RICO WHILE A
SECOND RIDGE AXIS EXTENDS FROM AN ANTICYCLONE NEAR 28N35W TO
13N50W. 40-50 KT WEST-SOUTHWESTERLY WINDS ALOFT LIE BETWEEN THE
TROUGH AND RIDGE AXES N OF 20N. THE REAR RIGHT QUADRANT OF THIS
JET LIES NEAR THE NE CARIBBEAN AND THE ASSOCIATED UPPER LEVEL
DIFFLUENCE IS ENHANCING THE CONVECTION NOTED IN THE SECTION
ABOVE NEAR THE TROPICAL WAVE FROM 20N58W TO 13N64W. THE UPPER
TROUGH IS EXPECTED TO CUT OFF A LOW NEAR 30N50W TOMORROW WHILE
THE ANTICYCLONE WILL WEAKEN AND A NEW ONE WILL FORM OVER THE
LESSER ANTILLES. THE INCREASED DIFFLUENCE ALOFT ASSOCIATED WITH
THE NEW ANTICYCLONE WILL HELP ENHANCE CONVECTION WITH THE
TROPICAL WAVE CURRENTLY FROM 12N45W TO 02N48W AS IT MOVES
WESTWARD TOWARD THE ISLANDS.

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

$$
SCHAUER




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