[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091809
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED AUG 09 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1700 UTC.

...SPECIAL FEATURE...

A STRONG TROPICAL WAVE LOCATED ABOUT 195 MILES EAST OF THE
WINDWARD ISLANDS IS MOVING WESTWARD AT 15 TO 20 KT. SHOWER AND
THUNDERSTORM ACTIVITY HAS BECOME MORE CONCENTRATED THIS
MORNING...AND AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL
REACH THE SYSTEM THIS AFTERNOON TO DETERMINE IF A TROPICAL
DEPRESSION OR STORM HAS FORMED.  REGARDLESS OF TROPICAL CYCLONE
DEVELOPMENT...THE SYSTEM WILL SPREAD SHOWERS AND THUNDERSTORMS
WITH GUSTY WINDS TO TROPICAL STORM FORCE IN SQUALLS OVER
PORTIONS OF THE LESSER ANTILLES LATER TODAY AND TONIGHT.
NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS APPROACHING THE
WINDWARD ISLANDS FROM 11N TO 16N BETWEEN 56W AND 61W. A SURFACE
LOW HAS BEEN REPLACED ON THE WAVE AXIS NEAR 13N55W DUE TO THIS
BURST ALONG WITH LOW CLOUD MOTIONS SPIRALING CYCLONICALLY INTO
THE SYSTEM.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 37W SOUTH OF 21N MOVING
WEST 15 KT. LOW CLOUD MOTIONS EXHIBIT CLEAR CYCLONIC CURVATURE
ABOUT THE AXIS WITH A NOTED INVERTED V PATTERN...ESPECIALLY N OF
11N BETWEEN 33W AND 42W. DEEP CONVECTION IN THE VICINITY OF THIS
WAVE HAS REMAINED AT A MINIMUM TODAY. ONLY ISOLATED SHOWERS AND
TSTMS EVIDENT WITHIN 250NM OF EITHER SIDE OF THE AXIS...AND
THOSE ARE MAINLY IN THE VICINITY OF THE ITCZ.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 84W SOUTH OF 24N
MOVING WEST 15 KT. SCATTERED MODERATE CONVECTION IS AFFECTING
CENTRAL AMERICA AND THE SW CARIBBEAN FROM 8N TO 15N BETWEEN 78W
AND 87W. THE NORTHERN PORTION OF THIS WAVE IS INTERACTING WITH
AN UPPER LOW PUSHING OFF THE W COAST OF FLORIDA...BUT CONVECTION
IN THIS VICINITY OF THE WAVE N OF 18N HAS DIMINISHED QUITE A BIT
SINCE YESTERDAY. ONLY ISOLATED SHOWERS AND THUNDERSTORMS ARE
NOTED IN THE NW CARIBBEAN AND SOUTHEAST/SOUTH CENTRAL GULF OF
MEXICO.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 13N16W 10N36W 10N39W 12N52W
11N57W TO INLAND OVER NE SOUTH AMERICA NEAR 8N66W. ISOLATED
MODERATE CONVECTION LIES JUST OFF THE W COAST OF AFRICA FROM 7N
TO 13N BETWEEN 13W AND 19W. ASIDE FROM THE SPECIAL
FEATURE...VERY LITTLE SIGNIFICANT CONVECTION IS NOTED ELSEWHERE
ALONG THE AXIS W OF 20W.

...DISCUSSION...
THE GULF OF MEXICO...
A MID TO UPPER LEVEL LOW IS SEEN SPINNING JUST OFF THE WEST
COAST OF FLORIDA IN THE ERN GULF THIS AFTERNOON. MID/UPPER LEVEL
ENE/E FLOW DOMINATES THE REST OF THE GULF AREA OUTSIDE OF THE
UPPER LOW...ON THE SOUTH SIDE OF UPPER ANTICYCLONES OVER N TEXAS
AND NE MISSISSIPPI. SCATTERED SHOWERS AND THUNDERSTORMS WITH
EMBEDDED ISOLATED MODERATE CONVECTION LIES IN THE SW GULF FROM
18N TO 25N BETWEEN 93W AND COASTAL MEXICO...AN AREA WHICH IS
UNDER THE INFLUENCE OF WEAK UPPER DIFFLUENCE. THERE ARE A FEW
ISOLATED SHOWERS IN THE CENTRAL GULF NEAR THE BASE OF THE UPPER
LOW OFF THE W COAST OF FLORIDA...BUT CLOUD TOPS REMAIN WARM AND
HEAVILY SHEARED. AT THE SURFACE...5 TO 15 KT E/SE FLOW
DOMINATES ON THE SW SIDE OF HIGH PRESSURE OVER N FLORIDA AND THE
WRN ATLC. THIS LOOKS TO CONTINUE OVER THE NEXT COUPLE OF
DAYS...WHILE THE UPPER LOW MOVES INTO THE WRN GULF.

THE CARIBBEAN SEA...
THE SOUTHERN PORTION OF THE UPPER LOW OFF OF W FLORIDA IS
EXTENDING INTO THE NW CARIBBEAN AND YUCATAN CHANNEL. A SMALL
CLUSTER OF MODERATE CONVECTION IS LOCATED NEAR CANCUN
MEXICO...LIKELY DUE TO THE INTERACTION OF THE UPPER LOW WITH THE
TROPICAL WAVE ALONG 84W. MID TO UPPER LEVEL ANTICYCLONIC MOTION
IS NOTED IN THE SW GULF OFF THE CENTRAL AMERICAN COAST. BROAD
UPPER NE/E FLOW IS DOMINATING MUCH OF THE CENTRAL AND ERN
CARIBBEAN. A LINE OF SCATTERED MODERATE CONVECTION IS EXTENDING
THROUGH THE MIDDLE CARIBBEAN WATERS FROM 13N TO 17N BETWEEN THE
WINDWARD ISLANDS AND 77W. THIS IS ASSOCIATED WITH LOW LEVEL
CONFLUENCE AND WEAK UPPER DIFFLUENCE. THE 09/12Z UW CIMMS
SAHARAN LAYER ANALYSIS SHOWS THIS CONVECTION IS ALSO ALONG A
DEMARCATION LINE ALONG THE EDGE OF THE LATEST SURGE OF AFRICAN
DUST. 15 TO 25KT TRADE FLOW CONTINUES TO DOMINATE MUCH OF THE
CARIBBEAN THIS AFTERNOON...WITH THE STRONGEST WINDS GENERALLY
BETWEEN THE COLOMBIAN COAST AND HISPANIOLA ...AS ATLC HIGH
PRESSURE TO THE NORTH INTERACTS WITH LOWER PRESSURE NEAR
COLOMBIA. SIMILAR CONDITIONS EXPECTED OVER THE NEXT COUPLE OF
DAYS...THOUGH SHOWERS AND TSTMS ASSOCIATED WITH THE SPECIAL
FEATURE NEARING THE WINDWARD ISLANDS WILL SPREAD THROUGH THE ERN
CARIBBEAN.

THE ATLANTIC OCEAN...
UPPER LEVEL N/NE FLOW DOMINATES MUCH OF THE SW ATLC BETWEEN THE
FLORIDA COAST AND 62W...BETWEEN THE UPPER HIGH OVER THE SE US
AND A WEAK UPPER LOW NEAR 21N60W...WHICH IS BEING CONSUMED BY
DRY AIR. A BROAD LAYER OF UPPER ANTICYCLONIC MOTION IS SEEN ON
WV IMAGERY AGAIN THIS AFTERNOON FROM 5N TO 30N BETWEEN THE
AFRICAN COAST AND 50W...WITH THE HIGH CENTER ESTIMATED TO BE
NEAR 19N30W. UPPER CYCLONIC MOTION IS EVIDENT IN THE ATLC WATERS
JUST SOUTH OF THE SPECIAL FEATURE...AS A MID TO UPPER LOW IS
NOTED OVER NE SOUTH AMERICA. SURFACE HIGH PRESSURE CONTINUES TO
DOMINATE MUCH OF THE ATLC WATERS FROM 15N TO 30N BETWEEN 20W AND
80W...WITH A 1020MB HIGH CENTER ANALYZED NEAR 29N73W AND A
1022MB CENTER NEAR 27N53W.


$$
WILLIS


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