[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131748
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUL 13 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
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 1715 UTC.

...SPECIAL FEATURE...
THE CENTER OF TROPICAL STORM EMILY IN THE ATLANTIC OCEAN WAS
NEAR 11.2N 58.1W AT 13/1500 UTC...MOVING WEST 17 KT. THE
ESTIMATED MINIMUM CENTRAL PRESSURE WAS 1003 MB. THE MAXIMUM
SUSTAINED WIND SPEED WAS 50 KT WITH GUSTS TO 60 KT. PLEASE
REFER TO THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. TROPICAL STORM AND
HURRICANE WATCHES AND WARNINGS HAVE BEEN ISSUED BY THE
GOVERNMENTS OF THE DIFFERENT COUNTRIES FROM VENEZUELA TO
MARTINIQUE. ONE BAND OF STRONG SHOWERS AND THUNDERSTORMS ALREADY
IS REACHING THE CARIBBEAN ISLANDS FROM JUST WEST OF GRENADA TO
THE SOUTHERN WATERS OF GUADELOUPE. THE PRECIPITATION IN THIS
BAND IS WITHIN 20 TO 30 NM ON EITHER SIDE OF THE CURVED LINE
16N58W 16N62W 14N62W 12N62W. OTHER STRONG SHOWERS AND
THUNDERSTORMS ALSO ARE FOUND FROM 10N TO 12N BETWEEN 60W AND 63W
AT THE SOUTHERN END OF THIS BAND. THE STORM CENTER STILL IS A
FEW HUNDRED KILOMETERS EAST OF THE SOUTHEASTERN CORNER OF THE
CARIBBEAN SEA. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ALSO
ARE IMMEDIATELY AROUND EMILY NOW...FROM 9.5N TO 12N BETWEEN 57W
AND 60W. STILL ANOTHER BAND OF LIGHTER SHOWERS AND THUNDERSTORMS
IS 100 TO 150 NM TO THE EAST OF THE CENTER.

...TROPICAL WAVES...

AN EASTERN ATLANTIC TROPICAL WAVE SHOWS UP CLEARLY ON VISIBLE
SATELLITE IMAGERY...ALONG 34W/35W SOUTH OF 17N MOVING WEST 10
TO 15 KT. THE SURFACE LOW PRESSURE CENTER FROM SIX HOURS AGO IS
NOT APPARENT ANY MORE. THE 13/0900 UTC QUIKSCAT DATA SHOWED NO
CLOSED CENTER ANY MORE IN THE WIND FIELD. SCATTERED MODERATE TO
STRONG SHOWERS AND THUNDERSTORMS FROM 16N TO 17N BETWEEN 34.5W
AND 36W. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS/POSSIBLE
THUNDERSTORMS...PARTLY IN THE ITCZ...FROM 8N TO 14N BETWEEN 30W
AND 40W.

A NOT-S0-EASY-TO-FIND TROPICAL WAVE CONTINUES TO THE WEST OF
THE 34W/35W WAVE ALONG 41W SOUTH OF 16N MOVING WEST 10 TO 15 KT.
WIDELY SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND
THUNDERSTORMS FROM 8N TO 10N BETWEEN 40W AND 45W...ALSO IN
THE ITCZ.

WESTERN CARIBBEAN SEA TROPICAL WAVE ALONG 86W SOUTH OF 18N
MOVING WEST 10 TO 15 KT. THIS WAVE IS MOVING THROUGH THE AREA
OF A MIDDLE TO UPPER LEVEL TROUGH...WHICH STARTS OUT IN THE
ATLANTIC OCEAN AND WHOSE BASE REACHES THE NORTHWESTERN CARIBBEAN
SEA. THIS TROUGH HAS BECOME MORE AND MORE STRETCHED OUT...
POSSIBLY BECOMING A SHEAR AXIS IN SOME AREAS ALONG IT. THIS
TROUGH IS THE SAME ONE WHICH HAS BEEN ASSOCIATED WITH THE DEEP
LAYER FEATURE OF THE LAST FEW DAYS...FROM NORTH OF 32N
EVENTUALLY MOVING MORE AND MORE SOUTHWARD...NOW REACHING THE
NORTHWESTERN CARIBBEAN SEA. THE STRONG SHOWERS AND THUNDERSTORMS
IN A FEW DIFFERENT CLUSTERS...WHICH ARE SOUTH OF 14N BETWEEN 77W
AND THE COASTS OF CENTRAL AMERICA FROM PANAMA TO NICARAGUA...ALSO
MAY BE RELATED TO SOME AMOUNT OF UPPER LEVEL DIFFLUENT FLOW IN
THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA. THE ISOLATED
MODERATE SHOWERS AND THUNDERSTORMS FROM 15N TO 17N BETWEEN 78W
AND 85W ARE DIRECTLY SOUTH OF THIS TROUGH/SHEAR AXIS.

...THE ITCZ...

THE ITCZ GOES FROM 11N14W TO 11N21W TO 13N29W...10N36W TO
9N40W...7N43W TO 10N51W...10N60W 10N65W. EARLIER SHOWERS AND
THUNDERSTORMS...SEEMINGLY ASSOCIATED WITH THE NEXT TROPICAL WAVE
YET TO LEAVE COMPLETELY FROM AFRICA...WERE IN THE AREA FROM 8N
TO 14N BETWEEN AFRICA AND 22W. THE CLOUD TOP TEMPERATURES IN
THIS AREA HAVE BEEN WARMING DURING THE LAST FEW  HOURS. ISOLATED
MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS FROM 1N TO 6N
BETWEEN 45W AND 52W...JUST REACHING SECTIONS OF NORTHEASTERN
SOUTH AMERICA.

...DISCUSSION...

THE GULF OF MEXICO...
BROAD UPPER LEVEL ANTICYCLONIC FLOW IS EVERYWHERE IN THE GULF OF
MEXICO. MIDDLE TO UPPER LEVEL DRY AIR IS IN MOST AREAS. ISOLATED
MODERATE SHOWERS HAVE DEVELOPED IN ONSHORE FLOW FROM THE LOWER
TEXAS COAST TO SOUTHERN MISSISSIPPI. WARMING CLOUD TOP
TEMPERATURES AND SOME REMAINING SHOWERS ARE FOUND FROM 20N TO
23N BETWEEN 97W AND 100W IN COASTAL MEXICO. THIS AREA APPEARS
TO BE MOVING WITH THE SURFACE WIND FLOW. A FLAT SURFACE ISOBARIC
PATTERN...LITTLE GRADIENT...EXISTS ACROSS THE OPEN GULF WATERS.
A MIDDLE TO UPPER LEVEL TROUGH...WHICH IS BEING STRETCHED AND
MAY BE A SHEAR AXIS ALONG SOME PARTS OF IT...EXTENDS FROM AN
ATLANTIC OCEAN/SOUTHERN BAHAMAS CYCLONIC CIRCULATION CENTER...
TO EASTERN CUBA...INTO THE NORTHWESTERN CARIBBEAN SEA...ACROSS
THE YUCATAN PENINSULA...TO A WEAKENING CYCLONIC CIRCULATION
CENTER THAT IS MOVING ACROSS MEXICO...JUST WEST OF THE ISTHMUS
OF TEHUANTEPEC.

THE CARIBBEAN SEA...
TROPICAL STORM EMILY IS STILL IN THE ATLANTIC OCEAN...SET TO
ENTER THE SOUTHEASTERN CORNER OF THE CARIBBEAN SEA. IT IS
FORECAST TO MOVE THROUGH THE SOUTHEASTERN CORNER OF THE AREA
AND BECOME A HURRICANE DURING THE NEXT 24 HOURS. AN 86W TROPICAL
WAVE IS MOVING THROUGH THE AREA OF A MIDDLE TO UPPER LEVEL
TROUGH/SHEAR AXIS...NOW FROM THE NORTHWESTERN CORNER OF THE AREA
THROUGH HONDURAS AND NICARAGUA INTO THE EASTERN PACIFIC OCEAN.
SHOWERS AND THUNDERSTORMS IN THE SOUTHWESTERN CORNER OF THE AREA
ALSO MAY BE RELATED TO SOME AMOUNT OF UPPER LEVEL DIFFLUENT FLOW.
READ MORE ABOUT THESE MAIN FEATURES IN THE SECTIONS ABOUT THE
TROPICAL STORM...AND IN THE TROPICAL WAVES SECTION. A BROAD AND
NOT-WELL-DEFINED MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION
CENTER IS NEAR 14N67W. CYCLONIC FLOW IS WITHIN 100 TO 120 NM
RADIUS OF THE CENTER.

THE ATLANTIC OCEAN...
UPPER LEVEL ANTICYCLONIC WIND FLOW SPILLS FROM THE GULF OF
MEXICO AND FLORIDA INTO THE WESTERN ATLANTIC OCEAN...BOWING OUT
TO 30N70W AND THEN CURVING SOUTHWESTWARD TO THE NORTHERN AND
CENTRAL BAHAMAS AROUND THE SOUTHERN BAHAMAS CYCLONIC CIRCULATION
CENTER. A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE ATLANTIC
OCEAN THROUGH 32N64W TO A SOUTHERN BAHAMAS CYCLONIC CIRCULATION
CENTER NEAR 21N73W...ENTERING THE CARIBBEAN SEA THROUGH THE
WINDWARD PASSAGE. ISOLATED MODERATE SHOWERS AND THUNDERSTORMS
FROM 21N TO 28N BETWEEN 63W AND 72W...AND FROM 30N TO 33N
BETWEEN 55W AND 63W...TO THE EAST OF THE TROUGH. A MIDDLE TO
UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CIRCULATION CENTER
NEAR 31N46W TO 18N49W. MIDDLE TO UPPER LEVEL DRY AIR IS AROUND
THIS TROUGH SOUTH OF 25N...AND IN GENERAL IS WITHIN 600 TO
700 NM NORTH AND NORTHWEST OF 24N24W 19N38W 12N45W. BROAD UPPER
LEVEL ANTICYCLONIC FLOW IS NORTH OF 20N EAST OF 40W. SURFACE
ANTICYCLONIC FLOW IS NORTH OF 20N BETWEEN AFRICA AND 80W.

$$
MT


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