[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281042
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT OCT 28 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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 1045 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 41W/42W S OF 13N MOVING W 10 TO 15 KT.
THIS WAVE REMAINS RATHER LOW AMPLITUDE AND IS LESS DEFINED THAN
IT WAS A COUPLE DAYS AGO...WITH LITTLE CURVATURE NOTED IN SAT
IMAGES AND AVAILABLE SFC DATA. HOWEVER...ANALYSIS OF A HOVMOLLER
DIAGRAM STILL SHOWS THE FEATURE TRACKING TO THE W. ISOLATED
MODERATE CONVECTION NOTED WITHIN 150 NM OF EITHER SIDE OF THE
AXIS.

A TROPICAL WAVE IS MOVING THROUGH THE WINDWARD ISLANDS...ALONG
60W S OF 21N MOVING W 10 TO 15 KT. A 1010 MB LOW IS ALONG THE
WAVE NEAR 13N. CLUSTERS OF SCATTERED MODERATE CONVECTION SEEN
FROM 10N-17N BETWEEN 55W-65W. SOME SLOW DEVELOPMENT IS POSSIBLE
WITH THIS SYSTEM DURING THE NEXT DAY OR SO. LOCALLY HEAVY RAINS
AND GUSTY WINDS WILL ALSO BE POSSIBLE AS THE SYSTEM MOVES ACROSS
MUCH OF THE LESSER ANTILLES AND ADJACENT EASTERN CARIBBEAN
WATERS TODAY AND TONIGHT.

A WEAK TROPICAL WAVE IS EXTENDING S FROM WRN HAITI ALONG 74W S
OF 18N MOVING W 10 TO 15 KT. THE POSITION IS BASED ON CONTINUITY
AS THE WAVE LACKS A CLEAR CUT SIGNATURE...AND MAY NEED TO BE
DROPPED EVENTUALLY AS IT INTERACTS WITH THE FRONTAL ZONE ABOUT
TO MOVE INTO THE NW CARIBBEAN. DEEP CONVECTION REMAINS MINIMAL
WITHIN 200NM OF THE EITHER SIDE OF THE AXIS.

 ...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N13W 8N38W 8N50W 12N58W. BESIDES
FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...SCATTERED MODERATE/ISOLATED STRONG IS WITHIN 175 NM N OF
THE AXIS BETWEEN 18W-38W. ISOLATED MODERATE CONVECTION NOTED IN
THE SAME AREA EXCEPT WITHIN 200NM S OF THE AXIS. SCATTERED
MODERATE/ISOLATED STRONG PATCHES NOTED FROM 6N-11N BETWEEN
44W-56W.

...DISCUSSION...
THE GULF OF MEXICO...
A STRONG COLD FRONT...ASSOCIATED WITH A SHARP UPPER TROUGH
EXTENDING SSW FROM THE GREAT LAKES...CONTINUES TO MOVE QUICKLY
SOUTHEASTWARD IN THE GULF. AS OF 28/0900 UTC...THE FRONT WAS
ANALYZED FROM THE FLORIDA BIG BEND TO NEAR COASTAL YUCATAN NEAR
21N90W...TO NEAR THE ISTHMUS OF TEHUANTEPEC NEAR 17N95W. A
CLUSTER OF MODERATE TO STRONG CONVECTION ASSOCIATED WITH THE
FRONT IS NOTED IN THE SOUTHERN BAY OF CAMPECHE AND SE
MEXICO...WITH MORE CONVECTIVE WEATHER FURTHER E IN THE WARM
SECTOR MOVING ACROSS THE SE GULF AND SE FLORIDA. THIS AREA AHEAD
OF THE FRONT WAS PREVIOUSLY ANALYZED AS A PREFRONTAL
TROUGH...BUT IT APPEARS THE MAIN COLD FRONT HAS CAUGHT UP AND
THUS THE TROF WAS LEFT OFF THE 0900 UTC MAP. STRONG NW/N WINDS
BETWEEN 20 AND 30 KT ARE COMMON BEHIND THE FRONT AS STRONG HIGH
PRESSURE BUILDS FROM THE NW...AND SHOULD DOMINATE THE ENTIRE
GULF BY THIS AFTERNOON. ASSOCIATED STEEP NW/N WIND WAVES WILL
RAPIDLY REPLACE THE PREFRONTAL WIND WAVES FROM THE SOUTH. FOR
MORE DETAILS IN WINDS AND WAVES ASSOCIATED WITH THIS FRONTAL
SYSTEM REFER TO MIAOFFNT4 AND MIAHSFAT2.

THE CARIBBEAN SEA...
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ASSOCIATED WITH A
RAPIDLY APPROACHING COLD FRONT FROM THE SE GULF IS AFFECTING THE
YUCATAN CHANNEL AND ADJACENT CARIBBEAN WATERS. THE TAIL END OF
AN OLD ATLC FRONTAL BOUNDARY/TROUGH CONTINUES TO LOOSE ITS
IDENTITY OVER THE N CARIBBEAN AND NRN HISPANIOLA. THERE ARE
STILL ISOLATED SHOWERS/TSTMS OVER THE WATERS SURROUNDING
CUBA...JAMAICA...AND HISPANIOLA ASSOCIATED WITH THIS OLD FRONTAL
SYSTEM. THIS ACTIVITY ALSO BEING SUPPORTED BY THE UPPER HIGH
OVER ERN CUBA NEAR 21N76W THAT HAS RIDGING EXTENDING E TO 60W
ALONG 20N. THE ISOLATED SHOWERS/TSTMS NOTED FROM 13N-20N BETWEEN
74W-85W ALSO BEING SUPPORTED BY UPPER DIFFLUENCE BETWEEN
THE UPPER HIGH OVER CUBA AND A WEAK UPPER LOW IN THE NW
CARIBBEAN NEAR 17N80W. SIMILAR SHOWERS NOTED JUST S OF THE
DOMINICAN REPUBLIC TO 15N...ANOTHER UPPER DIFFLUENT ZONE. MUCH
OF THE SRN CARIBBEAN S OF 15N BETWEEN 67W-83W IS EXPERIENCING
FAIR WEATHER WITH DRY MID TO UPPER AIR IN PLACE. THE TROPICAL
WAVE/LOW MOVING THROUGH THE WINDWARD ISLANDS IS BEGINNING TO
AFFECT THE ERN CARIBBEAN AND WILL SPREAD MOISTURE THROUGH THE
REGION OVER THE NEXT COUPLE OF DAYS. MEANWHILE...THE FRONT IN
THE GULF WILL MOVE INTO THE NW CARIBBEAN AND SLOW DOWN. SEE
MIAOFFNT3 FOR MORE INFO.

THE ATLANTIC OCEAN...
FROM W TO E...A HIGHLY AMPLIFIED RIDGE/TROUGH/RIDGE PATTERN
REMAINS ESTABLISHED ACROSS THE ATLC. SURFACE HIGH PRESSURE THAT
HAS PUSHED OFF THE EAST COAST IS INTERACTING WITH THE NEXT
STRONG FRONTAL SYSTEM TO PRODUCE WIDESPREAD 20-30 KT S WINDS IN
THE SW NORTH ATLC OFF THE COAST OF FLORIDA/BAHAMAS. THESE WINDS
WILL SHIFT W TO NW AT A SIMILAR MAGNITUDE BEHIND THE FRONT.
HEAVY SHOWERS WITH EMBEDDED TSTMS ALSO MOVING OFF THE COAST OF
FLORIDA AND THE SOUTHEAST STATES IN THE WARM SECTOR OF THE
FRONTAL SYSTEM. SEE MIAOFFNT3 FOR DETAILS SURROUNDING THE
WINDS/SEAS ASSOCIATED WITH THIS FRONT. OUR OLDER COLD FRONT
BOUNDARY LINGERS IN THE CENTRAL ATLC WATERS ALONG 32N43W 23N57W
AND THEN EXTENDS WSW AS A TROUGH TO THE TIP OF ERN CUBA.
ISOLATED SHOWERS/TSTMS NOTED WITHIN 100NM OF THIS BOUNDARY...BUT
OVERALL THE BOUNDARY SEEMS TO BE LOSING ITS IDENTITY. VERTICALLY
STACKED HIGH PRESSURE CONTINUES TO DOMINATED MUCH OF THE ERN
ATLC WITH THE UPPER HIGH CENTERED NEAR 27N34W AND A 1024 MB SFC
HIGH CENTERED NEAR 31N30W. THIS AREA ALSO DOMINATED BY DRY
STABLE AIR AND SCATTERED TO BROKEN STRATOCUMULUS. A WEAK 1012MB
LOW NOTED N OF THE CANARY ISLANDS NEAR 30N15W BUT LITTLE
CONVECTION IS ASSOCIATED WITH IT. IN THE DEEP TROPICS...UPPER
HIGH PRESSURE NOTED JUST E OF THE WINDWARD ISLANDS. UPPER
DIFFLUENCE BETWEEN THIS FEATURE AND A TROUGH EXTENDING NW FROM
NE SOUTH AMERICA IS HELPING SUPPORT THE CONVECTION WITH THE WAVE
ALONG 60W. AN UPPER LOW IS NOTED NEAR 16N40W WITH MINIMAL SHOWER
ACTIVITY NOTED NEAR THIS FEATURE.


$$
WILLIS




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