[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 280612
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT MAY 28 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

TROPICAL WAVE OVER THE FAR E ATLC IS ALONG 27W S OF 15N MOVING W
AT 15 KT.  THERE IS LITTLE OR NO SATELLITE SIGNATURE FOR THIS
WAVE AND THE CURRENT POSITION IS BASED PRIMARILY UPON
EXTRAPOLATION.  CONVECTION IS CONFINED TO THE ITCZ.

TROPICAL WAVE OVER THE CENTRAL ATLC IS ALONG 47W SOUTH OF 13N
MOVING W AT 15 KT. THIS WAVE IS ALSO POORLY DEFINED IN
SATELLITE IMAGERY WITH CURRENT POSITION BASED MAINLY UPON
EXTRAPOLATION AND PAST WAVE PROPAGATION SPEED.  LARGE AFRICAN
DUST SURGE IS SUPPRESSING CONVECTION WHICH IS CONFINED TO THE
ITCZ.

TROPICAL WAVE OVER THE E CARIBBEAN IS ALONG 68W S OF 18N MOVING
WEST AT 15 KT. THERE IS SOME CYCLONIC ROTATION NOTED WITHIN
THE LOW CLOUD FIELD NEAR THE WAVE.  SCATTERED MODERATE TO STRONG
CONVECTION IS NOTED INLAND OVER VENEZUELA FROM 6N-9N BETWEEN
64W-68W.

TROPICAL WAVE OVER THE W CARIBBEAN IS ALONG 83W S OF 16N MOVING
W AT 15 KT.  SATELLITE IMAGERY SHOWS SOME CURVATURE OVER THE SW
CARIBBEAN.  SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS
ALONG THE COAST OF COSTA RICA FROM 9N-12N BETWEEN 81W-83W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N10W 7N30W 9N40W 7N55W 8N60W.
CLUSTERS OF WIDELY SCATTERED MODERATE CONVECTION IS FROM 4N-9N
BETWEEN 12W-31W.  SCATTERED MODERATE CONVECTION IS FROM 4N-7N
BETWEEN 41W-44W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE RIDGING DOMINATES THE GULF OF MEXICO DUE TO A 1020 MB
HIGH OVER THE W ATLANTIC NEAR 30N69W.  WINDS ARE LIGHT FROM THE
E OR SE.  SCATTERED MODERATE TO STRONG CONVECTION IS MOSTLY
INLAND OVER S MEXICO FROM 16N-20N BETWEEN 89W-95W.  WIDELY
SCATTERED MODERATE CONVECTION IS ALSO INLAND ALONG THE FOOTHILLS
OF THE SIERRA MADRE ORIENTAL MOUNTAINS FROM 23N-30N BETWEEN
97W-101W.  IN THE UPPER LEVELS...A RIDGE EXTENDS FROM THE
YUCATAN PENINSULA TO LOUISIANA WITH AXIS ALONG 92W.  MOISTURE
AND HIGH CLOUDS ARE W OF THE RIDGE AXIS BETWEEN 92W-102W.
SUBSIDENCE COVERS THE REMAINDER OF THE GULF OF MEXICO.  EXPECT
A WEAK COLD FRONT CURRENTLY MOVING SWD OVER THE S UNITED STATES
WILL MOVE INTO N FLORIDA SAT AFTERNOON.  THE FRONT LOOKS TO BE
MOISTURE STARVED BUT MAY BE PRODUCE WIDELY SCATTERED SHOWERS/
THUNDERSTORMS ACROSS N FLORIDA.  THE REMAINDER OF THE GULF WILL
HAVE LIGHT SE TO S SURFACE FLOW.

CARIBBEAN SEA...
THE TWO TROPICAL WAVES ARE THE MAIN SURFACE FEATURE IN THE
CARIBBEAN.  SEE ABOVE.  AN AFRICAN DUST SURGE IS OVER THE E
CARIBBEAN BEHIND THE WAVE ALONG 68W MOVING WEST 15 KT.  THE
AIRMASS WILL CONTINUE TO SPREAD WESTWARD ACROSS THE AREA WITH
AREAS OF DUST...LOW LEVEL DRYING...AND DECREASED CHANCES OF
AFTERNOON SHOWERS/TSTMS IN ITS WAKE.  IN THE UPPER LEVELS...
A RIDGE PREVAILS OVER THE WESTERN CARIBBEAN W OF 80W WITH AXIS
FROM COSTA RICA TO THE YUCATAN PENINSULA.  UPPER LEVEL MOISTURE
IS NOTED OVER CENTRAL AMERICA.  THE BASE OF A TROUGH IS OVER THE
NORTHERN CARIBBEAN N OF 18N BETWEEN 60W-80W.  UPPER LEVEL
MOISTURE IS ALSO NOTED OVER THIS AREA TO INCLUDE JAMAICA...
HISPANIOLA...AND PUERTO RICO.  EXPECT THE TROPICAL WAVES TO
CONTINUE MOVING W IN THE NEXT 24 HOURS.

ATLANTIC OCEAN...
A 1020 MB HIGH IS OVER THE W ATLANTIC NEAR 30N69W.  A FRONTAL
TROUGH IS FURTHER E ALONG 32N57W 26N61W 22N70W.  BROKEN LOW
CLOUDS ARE WITHIN 120 NM OF THE TROUGH.  AN AREA OF SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS E OF THE TROUGH FROM
24N-28N BETWEEN 51W-56W.  A LARGE 1030 MB HIGH NEAR 37N35W
DOMINATES THE E ATLANTIC N OF 18N AND E OF 50W.  ELSEWHERE...
SATELLITE IMAGERY SHOWS AN EXPANSIVE AREA OF AFRICA DUST
COVERING THE ENTIRE AREA S OF 23N TO THE ITCZ E OF THE LESSER
ANTILLES.  IN THE UPPER LEVELS... A TROUGH-RIDGE- TROUGH PATTERN
PREVAILS IN THE UPPER LEVELS WITH A BROAD/FLAT TROUGH OVER THE W
ATLC W OF 60W...RIDGE OVER THE CENTRAL ATLC FROM THE LESSER
ANTILLES TO BEYOND 32N45W...AND TROUGH OVER THE E ATLC FROM THE
AZORES TO 10N40W.   EXPECT THE W EXTENT OF THE FRONTAL TROUGH TO
LIFT SLOWLY NWD AT THE SAME TIME A SHORTWAVE TROUGH IN THE UPPER
LEVELS MOVES ACROSS E CUBA AND THE BAHAMAS TOMORROW.  THIS
SHOULD PRODUCE INCREASING SHOWERS/TSTMS NE OF THE BAHAMAS SAT.
OVER THE E ATLC...SHARP UPPER LEVEL TROUGH DIPS WELL INTO THE
TROPICAL ATLC FROM THE AZORES THROUGH 25N30W TO 10N40W
CONTINUING AS A CYCLONIC SHEAR AXIS TO 10N60W.  DIFFLUENT FLOW S
AND E OF THE TROUGH AXIS IS FAVORING ITCZ ACTIVITY OVER THE
CENTRAL ATLC.  THE UPPER TROUGH IS EXPECTED TO CONTINUE
AMPLIFYING SEWD WITH MAIN ITCZ ACTIVITY SHIFTING EWD.

$$
FORMOSA


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