[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181159
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT AUG 18 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC.

...SPECIAL FEATURE...
THE CENTER OF HURRICANE DEAN PASS WELL SOUTH OF PUERTO RICO. AT
18/1200 UTC...THE CENTER OF HURRICANE DEAN WAS LOCATED NEAR
LATITUDE 15.4 NORTH... LONGITUDE 67.9 WEST OR ABOUT 615 MILES...
990 KM...EAST-SOUTHEAST OF KINGSTON JAMAICA AND ABOUT 250
MILES...400 KM...SOUTH-SOUTHEAST OF SANTO DOMINGO IN THE
DOMINICAN REPUBLIC. DEAN IS MOVING WEST 15 KT WITH MAXIMUM
SUSTAINED WIND SPEEDS NEAR 150 KT WITH HIGHER GUSTS. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 930 MB. EYE DIAMETER IS 15
NM. DEAN IS A CATEGORY FOUR MAJOR HURRICANE. PLEASE SEE THE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC OR THE LATEST PUBLIC ADVISORY UNDER
MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS INCLUDING THE MOST RECENT
WATCH AND WARNING INFORMATION. FOR STORM INFORMATION SPECIFIC TO
YOUR AREA...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...
PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL WEATHER OFFICE. ALL
INTERESTS IN THE CARIBBEAN SEA AND THE GULF OF MEXICO SHOULD
CLOSELY MONITOR THE PROGRESS OF DEAN.  NUMEROUS MODERATE TO
STRONG CONVECTION IS OVER THE ERN CARIBBEAN FROM 14N-16N BETWEEN
66W-66W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS
FROM 13N-18N BETWEEN 65W-70W.  A SRN FEEDER BAND HAS SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION FROM 10N-15N BETWEEN
61W-64W.

...TROPICAL WAVES...
A TROPICAL WAVE IS MOVING THROUGH THE E ATLC ALONG 35W MOVING W
NEAR 20 KT.  THIS WAVE CONTINUES TO EXHIBIT A BROAD ENVELOPE OF
CYCLONIC TURNING IN THE SURROUNDING LOW TO MID CLOUD
FIELD...ESPECIALLY FROM 12N-19N BETWEEN 30W-40W.  HOWEVER...DEEP
CONVECTION REMAINS MINIMAL NEAR THIS CIRCULATION WITH ONLY ONE
SMALL CLUSTER OF MODERATE CONVECTION NOTED NEAR 17N35W. A MORE
CONCENTRATED AREA OF SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS NEAR THE SRN PORTION OF THE AXIS FROM 4N-11N
BETWEEN 31W-38W...WHICH MAY BE MORE ASSOCIATED WITH SPEED
CONVERGENCE S OF THE ITCZ.

AN ATLC OCEAN TROPICAL WAVE IS ALONG 47W SOUTH OF 20N. THIS
WAVE IS GENERALLY MOVING W NEAR 15-20 KT...BUT THE MAIN AREA OF
CYCLONIC TURNING HAS HAD A SW COMPONENT OVER THE LAST COUPLE OF
DAYS. THE WAVE...AND THIS SW MOTION...SHOWS UP WELL IN THE 48 HR
ANIMATION OF THE UW-CIMSS SSMI/AMSRE TOTAL PRECIPITABLE WATER
PRODUCT.  WIDELY SCATTERED MODERATE CONVECTION IS FROM 10N-12N
BETWEEN 46W-51W.

A WRN CARIBBEAN SEA TROPICAL WAVE IS ALONG 83W SOUTH OF 19N
MOVING WEST 20-25 KT.  AN INVERTED V PATTERN REMAINS EVIDENT
WITH THIS WAVE.  SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS ALONG THE COAST OF HONDURAS FROM 16N-18N BETWEEN
84W-86W.  ISOLATED SHOWERS AND TSTMS ARE ELSEWHERE WITHIN 120 NM
OF THE AXIS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N16W 14N35W 9N50W 7N60W.  OUTSIDE
OF THE CONVECTION ALREADY DESCRIBED WITH THE TROPICAL WAVES AND
HURRICANE DEAN...DEEP CONVECTION IS MINIMAL NEAR THE ITCZ.
SCATTERED MODERATE ACTIVITY IS INLAND OVER AFRICA FROM 8N-11N
BETWEEN 12W-15W...WHICH SEEMS ASSOCIATED WITH THE NEXT TROPICAL
WAVE.

DISCUSSION...

THE GULF OF MEXICO...
A SURFACE RIDGE IS STARTING TO NUDGE OVER THE NE GULF OF
MEXICO.  A LINE OF THUNDERSTORMS ARE OVER S ALABAMA ...AND S
MISSISSIPPI MOVING W.  SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS FROM 30N-33N BETWEEN 87W-89W.  FURTHER W...T.D.
ERIN CONTINUES TO MOVE FURTHER INLAND OVER TEXAS.  SCATTERED
MODERATE CONVECTION IS FROM 29N-34N BETWEEN 98W-102W.  SURFACE
WINDS OVER MOST OF THE GULF OF MEXICO ARE FROM THE E TO SE AT 15
KT WITH MOSTLY FAIR WEATHER.  IN THE UPPER LEVELS... AN UPPER
LEVEL HIGH IS OVER CENTRAL TEXAS NEAR 32N99W.  UPPER LEVEL
MOISTURE IS OVER THE N GULF N OF 24N.  A SMALL UPPER LEVEL LOW
IS CENTERED OVER S FLORIDA NEAR 25N80W MOVING W .  CYCLONIC FLOW
IS E OF 90W.  EXPECT HURRICANE AND TROPICAL STORM CONDITIONS TO
SPREAD ACROSS THE SOUTHERN AND WESTERN GULF OF MEXICO TUE
THROUGH THU AS HURRICANE DEAN MOVES FROM THE NW CARIBBEAN TO WRN
GULF OF MEXICO.

THE CARIBBEAN SEA...
POWERFUL CATEGORY FOUR HURRICANE DEAN IS OVER THE ERN CARIBBEAN
AS DESCRIBED ABOVE.  DEAN WILL CONTINUE TO HAVE SIGNIFICANT
IMPACTS ON THE CARIBBEAN OVER THE NEXT SEVERAL DAYS.  A TROPICAL
WAVE IS ALSO OVER THE WRN CARIBBEAN SEA.  SEE ABOVE.  AN AREA OF
ISOLATED MODERATE CONVECTION IS ALONG THE COAST OF N COLOMBIA
FROM 10N-13N BETWEEN 75W-78W.  SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS OVER SRN GUATEMALA FROM 12N-15N BETWEEN
90W-93W.  IN THE UPPER LEVELS ...A TROUGH IS OVER THE NW
CARIBBEAN SEA N OF 15N AND W OF 80W.  AN UPPER LEVEL HIGH IS
OVER THE SW CARIBBEAN SEA NEAR 12N78W. IMPRESSIVE UPPER LEVEL
OUTFLOW IS NOTED WITH HURRICANE DEAN E OF 70W.  EXPECT...
HURRICANE DEAN TO MOVE W OVER THE CARIBBEAN THROUGH TUE.

THE ATLANTIC OCEAN...
A LARGE SCALE RIDGE DOMINATES THE ATLANTIC OCEAN...ANCHORED BY A
1031 MB HIGH OVER THE AZORES AT 39N30W PRODUCING WIDESPREAD FAIR
WEATHER AND MODERATE TRADES E OF 60W.  E/NE WINDS ARE A LITTLE
STRONGER AS DENOTED BY A RECENT QUIKSCAT PASS FROM 18N-30N
BETWEEN 25W-40W. THIS IS IN RESPONSE TO THE INTERACTION BETWEEN
THE HIGH TO THE N WITH THE LARGE TROPICAL WAVE TO ITS S ALONG
35W. IN THE UPPER LEVELS...AN UPPER LOW IS SPINNING NEAR S
FLORIDA.  LIFT AHEAD OF THIS FEATURE IS SUPPORTING SCATTERED
SHOWERS AND TSTMS OVER THE BAHAMAS AND ADJACENT WATERS S OF 28N
W OF 72W.  THE UPPER LOW WILL MOVE W INTO THE ERN GULF BY
TOMORROW EVENING.  UPPER RIDGING IS TO THE E OF THE UPPER LOW
WHICH IS STEERING DEAN WWD.  ANOTHER UPPER LOW IS NEAR 27N52W
MOVING W.  LIGHTNING DATA HAS BEEN DEPICTING A FEW ISOLATED
TSTMS ASSOCIATED WITH THIS FEATURE FROM 30N-32N BETWEEN
47W-55W.   UPPER RIDGING EXTENDING W FROM AFRICA GENERALLY
DOMINATES THE ERN ATLC.

$$
FORMOSA



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