[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180013 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...CORRECTED CARIBBEAN SECTION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI AUG 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2330 UTC.

...SPECIAL FEATURE...
THE CENTER OF HURRICANE DEAN AT 18/0000 UTC WAS NEAR 14.9N 65.1W
OR ABOUT 695 NM/1290 KM EAST-SOUTHEAST OF KINGSTON JAMAICA...AND
ABOUT 220 NM/410 KM SOUTH-SOUTHEAST OF SAN JUAN PUERTO RICO.
DEAN IS MOVING WEST 19 KT WITH MAXIMUM SUSTAINED WIND SPEEDS
NEAR 115 KT WITH HIGHER GUSTS. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 946 MB. DEAN IS NOW 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. NUMEROUS MODERATE TO STRONG
CONVECTION IS OVER THE ERN CARIBBEAN FROM 12N-18N BETWEEN
61W-68W. THE EYE OF DEAN IS NOW APPARENT VIA THE SAN JUAN RADAR.
ALL INTERESTS IN THE CARIBBEAN SEA AND THE GULF OF MEXICO SHOULD
CLOSELY MONITOR THE PROGRESS OF DEAN.

...TROPICAL WAVES...
A TROPICAL WAVE IS MOVING THROUGH THE E ATLC ALONG 32W 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 28W-37W. HOWEVER...DEEP
CONVECTION REMAINS MINIMAL NEAR THIS CIRCULATION WITH ONLY ONE
SMALL CLUSTER OF MODERATE CONVECTION NOTED NEAR 16N32W. A MORE
CONCENTRATED AREA OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS NEAR THE SRN PORTION OF THE AXIS FROM 6N-10N
BETWEEN 24W-34W...WHICH MAY BE MORE ASSOCIATED WITH SPEED
CONVERGENCE S OF THE ITCZ.

AN ATLC OCEAN TROPICAL WAVE IS ALONG 44W 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. REGARDLESS...DEEP CONVECTION REMAINS MINIMAL NEAR THE
WAVE.

A WRN CARIBBEAN SEA TROPICAL WAVE IS ALONG 80W SOUTH OF 19N
MOVING WEST 20-25 KT. AN INVERTED V PATTERN REMAINS EVIDENT WITH
THIS WAVE. SCATTERED MODERATE CONVECTION IS OVER THE SW
CARIBBEAN S OF 11N. ISOLATED SHOWERS AND TSTMS ARE ELSEWHERE
WITHIN 120 NM OF THE AXIS. CLOUD TOPS OVER THIS ACTIVITY ARE
BEING SHEARED TO THE NE WITH UPPER SW FLOW AHEAD OF AN UPPER
TROUGH.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 16N16W 15N23W 16N30W 12N35W 11N42W
7N47W 15N59W. OUTSIDE OF THE CONVECTION ALREADY DESCRIBED WITH
THE TROPICAL WAVES AND HURRICANE DEAN...DEEP CONVECTION IS
MINIMAL NEAR THE ITCZ TONIGHT. SCATTERED MODERATE/ISOLATED
STRONG ACTIVITY IS INLAND OVER AFRICA THOUGH...FROM 8N-15N
BETWEEN 6W-12W...WHICH SEEMS ASSOCIATED WITH THE NEXT TROPICAL
WAVE.

DISCUSSION...

THE GULF OF MEXICO...
THE GULF IS MUCH QUIETER THIS EVENING AS T.D. ERIN CONTINUES TO
MOVE FURTHER INLAND OVER TEXAS. LIGHTNING DATA STILL SUPPORTS A
FEW ISOLATED TSTMS MAINLY NEAR THE NRN GULF COAST N OF 25N
BETWEEN 85W-95W. THIS MOISTURE EXPECTED TO CONTINUE MOVING
FURTHER INLAND WITH ERIN OVER THE NEXT DAY OR SO. FAIRLY UNIFORM
UPPER NE FLOW IS OVER THE GULF TONIGHT BETWEEN THE UPPER HIGH
OVER ERN TEXAS AND THE UPPER LOW NEARING FLORIDA FROM THE WRN
ATLC. SFC RIDGING HAS BUILT OVER THE N GULF AND WILL SLIDE N
THROUGH THE WEEKEND. HOWEVER...HURRICANE AND TROPICAL STORM
CONDITIONS ARE EXPECTED TO SPREAD ACROSS THE SOUTHERN AND
WESTERN GULF MON THROUGH WED AS HURRICANE DEAN MOVES ACROSS THE
NW CARIBBEAN AND ENTERS THE SW GULF TUE AND WED.

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 FEW DAYS. AN UPPER TROUGH
EXTENDS THROUGH THE NW CARIB BETWEEN CENTRAL CUBA AND ERN
HONDURAS. THIS IS EXPECTED TO PUSH W INTO THE GULF AND WEAKEN
OVER THE NEXT FEW DAYS WITH RIDGING STAYING N OF DEAN...KEEPING
IT ON A WWD TRACK. UPPER CONFLUENCE BETWEEN THIS UPPER TROUGH
AND OUTFLOW FROM DEAN IS PRODUCING A SWATH OF DRY UPPER AIR S OF
HISPANIOLA AT THE MOMENT...BUT THIS WILL ALSO SHIFT W. THE
TROPICAL WAVE CURRENTLY ALONG 80W WILL PUSH OUT OF THE CARIBBEAN
AND THROUGH CENTRAL AMERICA OVER THE NEXT COUPLE OF DAYS.

THE ATLANTIC OCEAN...
THE DOMINANT FEATURE OVER THE WRN ATLC CONTINUES TO BE THE UPPER
LOW SPINNING NEAR THE NW BAHAMAS. 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 27N50W. LIGHTNING DATA HAS BEEN DEPICTING A FEW ISOLATED
TSTMS ASSOCIATED WITH THIS FEATURE FROM 27N-32N BETWEEN 47W-52W.
UPPER RIDGING EXTENDING W FROM AFRICA GENERALLY DOMINATES THE
ERN ATLC. AT THE SFC A LARGE SCALE RIDGE DOMINATES...ANCHORED BY
A 1031 MB HIGH JUST N OF THE AZORES AT 40N27W. THIS IS 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-27N BETWEEN 25W-41W. THIS IS IN RESPONSE TO THE INTERACTION
BETWEEN THE HIGH TO THE N WITH THE LARGE TROPICAL WAVE TO ITS S
ALONG 32W.

$$
WILLIS


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