[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 111711
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUL 10 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...SPECIAL FEATURE....

THE CENTER OF HURRICANE BERTHA AT 11/1500 UTC IS NEAR 28.5N
62.0W...OR ABOUT 310 MILES SOUTH-SOUTHEAST OF BERMUDA. BERTHA IS
MOVING SLOWLY NORTHWESTWARD OR 320 DEGREES AT 5 KT. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 980 MB. BERTHA REMAINS A
CATEGORY 1 HURRICANE ON THE SAFFIR-SIMPSON SCALE WITH MAXIMUM
SUSTAINED WIND SPEEDS OF 75 KT WITH GUSTS TO 90 KT. LARGE SWELLS
AND HIGH SURF CONTINUE TO AFFECT BERMUDA AND ARE EXPECTED TO
PERSIST FOR THE NEXT FEW DAYS. SATELLITE IMAGERY DISPLAYS LITTLE
CHANGE IN THE OVERALL CLOUD PATTERN SURROUNDING BERTHA. THIS
DATA COMBINED WITH LOW WIND SHEAR SUGGEST THAT THE INTENSITY
WILL NOT CHANGE GREATLY OVER THE NEXT FEW DAYS. AFTER 48
HOURS...BERTHA IS EXPECTED TO ENCOUNTER INCREASED SHEAR AND
COOLER WATERS... RESULTING IN GRADUAL WEAKENING. THE FIRST
RECONNAISSANCE MISSION IS SCHEDULED FOR LATER TODAY. AT 1500 UTC
THE BERMUDA WEATHER SERVICE HAS ISSUED A TROPICAL STORM WATCH
FOR BERMUDA. INTERESTS IN THE ISLAND SHOULD CLOSELY MONITOR THE
PROGRESS OF BERTHA DURING THE NEXT SEVERAL DAYS. PLEASE REFER TO
THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A WELL-DEFINED TROPICAL WAVE ALONG 40W/41W SOUTH OF 15N IS
MOVING WEST AROUND 15 KT. AN INVERTED-V PATTERN AS WELL AS BROAD
CYCLONIC TURNING ARE CLEARLY OBSERVED ON VISIBLE SAT.
UPPER-LEVEL EASTERLY WINDS HAVE DISPLACED ASSOCIATED DEEP
CONVECTION TO THE WEST OF THE AXIS...EMBEDDED WITHIN THE ITCZ.
WIND DATA FROM THE THE LATEST QUIKSCAT PASS SUPPORT THE POSITION
OF THE AXIS.

A TROPICAL WAVE IS ALONG 67W SOUTH OF 17N MOVING WEST AT 15 KT.
MODERATE SUBSIDENCE OVER THE CENTRAL CARIBBEAN IS INHIBITING
DEEP CONVECTION WITH THIS WAVE...HOWEVER CLUSTERS OF MODERATE TO
STRONG CONVECTION ARE ALONG THE SOUTHERN EXTENT OF THE AXIS
INLAND OVER VENEZUELA.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N13W 6N25W 11N40W AND INTO SOUTH
AMERICA NEAR 8N59W. SCATTERED MODERATE CONVECTION IS FROM 6N TO
11N BETWEEN 16W AND 20W. SIMILAR CONVECTION IS WITHIN 90 NM OF
THE AXIS BETWEEN 22W-25W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 4N TO 9N BETWEEN 26W-34W. SCATTERED MODERATE
TO STRONG CONVECTION IS WITHIN 120 NM OF THE AXIS FROM 42W TO
56W.

...DISCUSSION...

THE GULF OF MEXICO...
THE GULF IS FAIRLY TRANQUIL THIS AFTERNOON. EASTERLY FLOW AROUND
THE SOUTHERN PERIPHERY OF AN E/W ELONGATED UPPER RIDGE BLANKETS
THE REGION. UPPER LEVEL DIVERGENCE IS PROVIDING THE ONLY SOURCE
OF CONVECTIVE ACTIVITY...ALLOWING A CLUSTER OF SCATTERED
SHOWERS AND THUNDERSTORMS TO EMERGE IN THE SW BAY OF CAMPECHE
BETWEEN VERACRUZ AND TAMPICO MEXICO. THE RIDGE IS TRANSPORTING
UPPER LEVEL MOISTURE OVER THE EASTERN GULF E OF 88W. THE
REMAINDER OF THE GULF IS MOSTLY CLEAR UNDER A DRY AND STABLE AIR
MASS. AT THE SFC...A HIGH PRESSURE RIDGE EXTENDS FROM THE W ATLC
ACROSS FLORIDA TO MEXICO...PROVIDING RETURN FLOW OF 10-15 KT
ACROSS THE REGION. EXPECT A WEAK COLD FRONT TO ENTER N FLORIDA
LATE SAT...BRINGING A CHANCE OF SCATTERED SHOWERS AND
THUNDERSTORMS TO THE NE GULF.

THE CARIBBEAN SEA...
A MID-UPPER LEVEL TROUGH EXTENDS FROM THE W ATLC OVER CUBA AND
THE NW CARIBBEAN N OF 17N. AN UPPER RIDGE ANCHORED ON AN UPPER
HIGH OVER THE SW CARIBBEAN IS S OF THE TROUGH. DIFFLUENT FLOW
ASSOCIATED WITH THESE FEATURES IS ENHANCING SCATTERED MODERATE
CONVECTION IN THE WESTERN CARIBBEAN BETWEEN 81W-86W S OF 20N.
ONSHORE FLOW IS ALSO FUELING SCATTERED SHOWERS AND THUNDERSTORMS
ALONG THE COAST OF NICARAGUA. ADDITIONAL CLUSTERS OF SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED IN RESPONSE TO LOW-LEVEL WIND
SPEED CONVERGENCE IN THE SW CARIBBEAN S OF 12N. THE CENTRAL AND
EASTERN CARIBBEAN REMAIN MOSTLY CLEAR DUE TO MODERATE SUBSIDENCE
ALOFT. A TIGHT PRESSURE GRADIENT CONTINUES TO PRODUCE MODERATE
TO STRONG TRADE WINDS ACROSS THE BASIN...WITH THE STRONGEST...UP
TO 30 KT...ALONG THE COLOMBIAN COAST.

THE ATLANTIC OCEAN...
A STATIONARY MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
NEAR 26N73W EXTENDS A TROUGH ACROSS THE W ATLC OVER CUBA AND
INTO THE CARIBBEAN. A DEEP-LAYERED TROUGH N OF THE DISCUSSION
AREA IS SUPPORTING A COLD FRONT AND AN ASSOCIATED BAND OF
SHOWERS AND THUNDERSTORMS N OF 30N. WITH THE EXCEPTION OF
HURRICANE BERTHA...A SURFACE RIDGE DOMINATES THE REMAINDER OF
THE ATLC DISCUSSION AREA WITH A 1027 MB HIGH CENTERED NEAR
32N33W. THIS SFC HIGH PAIRED WITH LOWER PRES OVER WESTERN AFRICA
IS PRODUCING A SWATH OF MODERATE TO STRONG NE WINDS N OF 20N AND
E OF 20W. FAIR-WEATHER CUMULUS CLOUDS FLOW AROUND THE RIDGE WITH
NO SIGNIFICANT CONVECTION TO SPEAK OF.

$$
WADDINGTON


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