[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE JUL 15 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
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM BERTHA IS CENTERED NEAR 35.6N 62.7W AT 15/1500
UTC OR ABOUT 225 NM NORTH-NORTHEAST OF BERMUDA. THE MINIMUM
CENTRAL PRESSURE IS 995 MB. THE MAXIMUM SUSTAINED WIND SPEED IS
60 KT WITH GUSTS TO 75 KT. PLEASE SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE
DETAILS. BERTHA IS MAINTAINING STRONG TROPICAL STORM STRENGTH
AND IS FORECAST TO GRADUALLY INTENSIFY SLIGHTLY TO A HURRICANE
AGAIN. LARGE SWELLS AND HIGH SURF ARE AFFECTING BERMUDA AND ARE
EXPECTED TO GRADUALLY DECREASE DURING THE NEXT COUPLE OF DAYS AS
BERTHA TURNS EASTWARD AND MOVES FARTHER AWAY FROM BERMUDA.
DANGEROUS RIP CURRENTS ARE ALSO OCCURRING ALONG THE U.S. EAST
COAST FROM THE CAROLINAS THROUGH SOUTHERN NEW ENGLAND. THE
DEEPEST CONVECTION IS WITHIN 120 NM OF THE CENTER OVER THE
NORTHERN SEMICIRCLE WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS COVERING A BROAD AREA ELSEWHERE FROM 33N-38N
BETWEEN 58W-64W.

STRONG TROPICAL WAVE IS ALONG 48W S OF 18N MOVING W NEAR 15 KT
WITH A 1012 MB LOW ANALYZED ALONG THE AXIS NEAR 12N MOVING
ROUGHLY WNW NEAR 15 KT. SATELLITE IMAGERY SHOWS A LARGE WELL
DEFINED ENVELOPE OF CYCLONIC ROTATION...FOCUSED NEAR THE LOW
CENTER. SCATTERED MODERATE CONVECTION IS MAINLY WEST OF THE AXIS
FROM 11N-14N BETWEEN 47W-53W. THIS SYSTEM HAS GENERALLY BECOME
LESS ORGANIZED AND THE POSSIBILITY OF A TROPICAL DEPRESSION TO
FORM IS DECREASING.

...TROPICAL WAVES...

NEW TROPICAL WAVE IS INTRODUCED OFF THE COAST OF AFRICA ALONG
28W/29W S OF 18N. THE AREA OF CLOUDINESS ASSOCIATED WITH THE
WAVE HAS BEEN TRACKED FOR SEVERAL DAYS NOW AS IT MOVED WWD AND
NOW SHOWS SOME APPARENT CYCLONIC TURNING. SCATTERED MODERATE
CONVECTION IS MOSTLY W OF THE AXIS FROM 3N-9N BETWEEN 28W-35W.

TROPICAL WAVE EXTENDS FROM EASTERN DOMINICAN REPUBLIC TILTED
ALONG 70W MOVING W 15 KT. THIS FEATURE REMAINS WELL DEFINED WITH
IR SATELLITE IMAGERY SHOWING INVERTED-V CURVATURE ALONG THE AXIS
IN THE ERN CARIBBEAN. A LARGE AREA OF SCATTERED MODERATE AND
EMBEDDED ISOLATED STRONG CONVECTION IS FROM 13N-17N BETWEEN
67W-74W.

THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N16W 12N27W 8N39W 10N57W 9N83W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 5N-9N
BETWEEN 11W-16W. SCATTERED MODERATE CONVECTION IS FROM SIMILAR
CONVECTION IS FROM 8N-11N BETWEEN 79W-82W.

...DISCUSSION...

GULF OF MEXICO...
DEEP LAYERED TROUGH IS OVER THE ERN U.S. DIPPING S TO THE N GULF
COAST PROVIDING SUPPORT FOR A STATIONARY FRONTAL BOUNDARY AT THE
SURFACE ALONG THE N GULF COAST. A WEAK 1012 MB LOW IS LOCATED
NEAR TALLAHASSEE FLORIDA ANALYZED WITH A SURFACE TROUGH
EXTENDING WSW. THIS SURFACE LOW PRESSURE COUPLED WITH THE
DIFFLUENCE AHEAD OF THE UPPER TROUGH IS GENERATING SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ALONG THE N GULF. ACTIVITY
HAS DECREASED SINCE EARLIER THIS MORNING BUT IS STILL PRESENT
FROM 26N-29N BETWEEN 85W-87W AND FROM 26N-30N BETWEEN 88W-94W.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE ALSO ACROSS THE
SE GULF AND SRN FLORIDA. STRONG SUBSIDENCE AND DRY STABLE AIR
ARE NORTH OF THE STATIONARY BOUNDARY THAT EXTENDS ACROSS THE SE
CONUS. AN UPPER HIGH IS OVER CENTRAL TEXAS WITH THE RIDGE AXIS
EXTENDING SE TO THE CENTRAL GULF OF MEXICO. THIS UPPER LEVEL
DIFFLUENT PATTERN IS ENHANCING THE TSTM ACTIVITY OVER THE NRN
GULF AS WELL AS AIDING IN THE AFOREMENTIONED CLUSTERS OF
SCATTERED SHOWERS/THUNDERSTORMS OVER THE ERN GULF E OF 85W.

CARIBBEAN SEA...
AN UPPER TROUGH DOMINATES THE CENTRAL CARIBBEAN DRYING THE AIR
NEAR ITS AXIS CAUSING TRANQUIL WEATHER ON THE SURFACE.
HOWEVER...UPPER DIFFLUENCE  BETWEEN THE TROUGH AND THE UPPER
RIDGE THAT COVERS THE GULF OF MEXICO IS PROVIDING ABUNDANT UPPER
LEVEL MOISTURE ACROSS THE NW CARIBBEAN SEA. THE ITCZ CROSSES THE
SW CARIBBEAN FROM NRN COLOMBIA ACROSS PANAMA INTO THE E PACIFIC
REGION GENERATING SCATTERED SHOWERS AND TSTMS ALONG COASTAL
PANAMA AND COSTA RICA BETWEEN 78W-83W. THE ERN CARIBBEAN IS
DOMINATED BY AN UPPER HIGH ANCHORED OVER THE WINDWARD ISLANDS
WHICH IS ENHANCING THE CONVECTIVE ACTIVITY ASSOCIATED WITH THE
TROPICAL WAVE ALONG 70W.

ATLANTIC OCEAN...
TROPICAL STORM BERTHA IS PULLING N AWAY FROM BERMUDA...SEE
ABOVE. BROAD UPPER LEVEL TROUGHING IS ACROSS THE ERN U.S.
SEABOARD AND THE FAR W ATLC WATERS. THIS ALONG WITH A SMALL
UPPER RIDGE FROM 31N72W TO 28N80W IS PROVIDING AMPLE DIFFLUENCE
TO GENERATE SCATTERED SHOWERS AND TSTMS WITHIN 90 NM OF A LINE
FROM 30N75W ACROSS GRAND BAHAMA ISLAND TO NEAR THE STRAITS OF
FLORIDA. A BROAD DEEP LAYERED TROUGH IS OVER THE CENTRAL ATLC N
OF 18N BETWEEN 35W-55W WITH A DISSIPATING ASSOCIATED COLD FRONT
NORTH OF THE AREA AND SURFACE TROUGH ENTERING THE AREA NEAR
32N43W TO 28N49W. SCATTERED SHOWERS ARE WITHIN 120 NM EITHER
SIDE OF THE TROUGH. A LARGE UPPER LEVEL HIGH IS CENTERED OVER
THE SOUTH CENTRAL AND WEST TROPICAL ATLC NEAR 15N62W. A WEAKER
UPPER HIGH IS NEAR 16N41W. THE COMBINATION OF THESE TWO HIGHS IS
CAUSING DIFFLUENCE ALOFT WHICH SUPPORTS THE CONVECTION
ASSOCIATED WITH THE TROPICAL WAVE NEAR 48W. ANOTHER UPPER LEVEL
HIGH IS WEST OF THE CANARY ISLANDS NEAR 29N22W COVERING THE ERN
ATLC E OF 35W. A SURFACE RIDGE OF HIGH PRESSURE EXTENDS ACROSS
THE ERN ATLC ANCHORED ON A 1036 MB HIGH CENTERED WELL N OF THE
AZORES.

$$
WALTON/CANGIALOSI


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