[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 280605
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0545 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 40W/41W S OF 13N MOVING W NEAR 10 KT.
THIS WAVE REMAINS RATHER LOW AMPLITUDE AND HAS BECOME LESS
DEFINED THAN IT WAS...WITH LITTLE CURVATURE NOTED IN SAT IMAGES
AND AVAILABLE SFC DATA. HOWEVER...ANALYSIS OF A HOVMOLLER
DIAGRAM STILL SHOWS THE FEATURE TRACKING SLOWLY TO THE W. A
CLUSTER OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
9N-11N BETWEEN 38W-41W...WITH ISOLATED SHOWERS/TSTMS NOTED
ELSEWHERE WITHIN 150NM OF THE AXIS.

A TROPICAL WAVE IS ALONG 59W/60W S OF 21N MOVING W 10 TO 15 KT.
A 1009 MB LOW IS ALONG THE WAVE NEAR 14N. THE AXIS IS CURRENTLY
BETWEEN BARBADOS AND THE MAIN WINDWARD ISLAND CHAIN...AND IS
WELL REPRESENTED WITH THE AVAILABLE SURFACE OBSERVATIONS ALONG
WITH PRONOUNCED CYCLONIC CURVATURE SEEN IN SATELLITE IMAGERY.
SCATTERED MODERATE CONVECTION STILL NOTED FROM 9N-15N BETWEEN
58W-64W. ALTHOUGH SHOWER AND THUNDERSTORM ACTIVITY HAS CHANGED
LITTLE THIS EVENING...UPPER-LEVEL WINDS ARE EXPECTED TO BECOME
SOMEWHAT MORE FAVORABLE FOR SOME ADDITIONAL DEVELOPMENT DURING
THE NEXT DAY OR SO.  THIS SYSTEM COULD PRODUCE LOCALLY HEAVY
RAINS AND GUSTY WINDS AS IT MOVES ACROSS MUCH OF THE LESSER
ANTILLES AND ADJACENT WATERS TONIGHT AND SATURDAY.

A WEAK TROPICAL WAVE IS EXTENDING S FROM HAITI ALONG 72W/73W 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 ZONES TO ITS
N AND NW. DEEP CONVECTION REMAINS MINIMAL WITHIN 200NM OF THE
EITHER SIDE OF THE AXIS.

 ...THE ITCZ...
ITCZ AXIS IS ALONG 10N14W 7N25W 6N44W 12N58W. BESIDES FOR THE
CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED
MODERATE IS WITHIN 200 NM N AND 140 NM S OF THE AXIS BETWEEN
22W-38W. SIMILAR ACTIVITY IS WITHIN 150 NM EITHER SIDE BETWEEN
45W-55W.

...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 28/2100 UTC...THE FRONT WAS
ANALYZED FROM THE SW TIP OF GEORGIA TO THE CENTRAL GULF NEAR
23N90W...TO NEAR THE ISTHMUS OF TEHUANTEPEC NEAR 18N95W THEN NWD
ALONG THE E SLOPES OF THE SIERRA MADRE MOUNTAINS NEAR 24N99W.
SCATTERED MODERATE CONVECTION ASSOCIATED WITH THE FRONT IS NOTED
IN THE CENTRAL BAY OF CAMPECHE...BUT MORE CONVECTIVE WEATHER
LIES FURTHER E IN THE WARM SECTOR MOVING ACROSS NE FLORIDA AND
THE APALACHEE BAY WHERE A SQUALL LINE IS ANALYZED. A PREFRONTAL
TROUGH IS ALSO SPARKING NUMEROUS MODERATE/ISOLATED STRONG
CONVECTION FROM THE YUCATAN CHANNEL NNE TO NEAR TAMPA. STRONG
NW/N WINDS BETWEEN 20 AND 30 KT ARE COMMON BEHIND THE FRONT AND
SIMILAR MAGNITUDE SWLY WINDS AHEAD OF THE FRONT AS STRONG SFC
HIGH PRES BUILD IN. FOR MORE DETAILS IN WINDS AND WAVES
ASSOCIATED WITH THIS FRONTAL SYSTEM REFER TO MIAOFFNT4 AND
MIAHSFAT2. THIS FAST MOVING FRONT WILL LIKELY CLEAR THE ENTIRE
GULF BY EARLY THIS AFTERNOON.

THE CARIBBEAN SEA...
A PREFRONTAL TROUGH ASSOCIATED WITH THE STRONG COLD FRONT MOVING
THROUGH THE GULF CLIPS THE CARIBBEAN WATERS THROUGH THE YUCATAN
CHANNEL...PRODUCING CLUSTERS OF MODERATE CONVECTION IN THE AREA.
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 21N77W THAT HAS RIDGING EXTENDING
E TO 60W ALONG 20N. MOST OF THE SHOWERS/TSTMS NOTED FROM 13N-20N
BETWEEN 75W-82W...WHICH IS AN UPPER DIFFLUENT REGION BETWEEN THE
UPPER HIGH OVER CUBA AND A WEAK UPPER LOW IN THE NW CARIBBEAN
NEAR 17N81W. SIMILAR SHOWERS NOTED JUST S OF THE DOMINICAN
REPUBLIC TO 15N...ANOTHER UPPER DIFFLUENT ZONE. MUCH OF THE SRN
CARIBBEAN 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. 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. HEAVY
SHOWERS WITH EMBEDDED TSTMS ALSO MOVING OFF THE COAST OF FLORIDA
AND SE COAST OF FLORIDA IN THE WARM SECTOR OF THE FRONTAL
SYSTEM. SEE MIAOFFNT3 FOR DETAILS SURROUNDING THE WINDS/SEAS
ASSOCIATED WITH THIS FRONT. THE OLDER COLD FRONT BOUNDARY
LINGERS IN THE CENTRAL ATLC WATERS ALONG 32N44W 25N55W AND THEN
EXTENDS WSW AS A TROUGH TO THE TIP OF ERN CUBA. ISOLATED
SHOWERS/TSTMS NOTED WITHIN 100NM OF THIS BOUNDARY. VERTICALLY
STACKED HIGH PRESSURE CONTINUES TO DOMINATED MUCH OF THE ERN
ATLC WITH THE UPPER HIGH CENTERED NEAR 26N32W AND A 1024 MB SFC
HIGH CENTERED NEAR 34N27W. THIS AREA ALSO DOMINATED BY DRY
STABLE AIR AND SCATTERED TO BROKEN STRATOCUMULUS. 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/CANGIALOSI




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