[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 051800
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI SEP 05 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM HANNA IS CENTERED NEAR 29.8N 78.5W AT 05/1800 UTC
OR ABOUT 140 NM EAST-NORTHEAST OF DAYTONA BEACH FLORIDA AND
ABOUT 270 NM SOUTH OF WILMINGTON NORTH CAROLINA MOVING N AT 17
KT. THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY THE
HURRICANE HUNTER IS 981 MB. MAXIMUM SUSTAINED WIND SPEED IS 60
KT WITH GUSTS TO 75 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.
SOUTHERLY UPPER WINDS ARE PRODUCING SHEAR OVER HANNA AND COUPLED
WITH DRY AIR ARE LIMITING CONVECTION TO THE S OF THE CENTER.
HANNA IS NOT FORECAST TO BECOME A HURRICANE PRIOR TO LANDFALL
BUT IT WOULD ONLY TAKE A SMALL INCREASE IN WIND SPEED FOR HANNA
TO BECOME A HURRICANE. SCATTERED MODERATE/STRONG CONVECTION IS
FROM 28N-31N BETWEEN 78W-80W WITH SCATTERED SHOWERS/
THUNDERSTORMS COVERING THE REMAINDER OF THE AREA N OF 26N TO
BEYOND 32N W OF 77W TO INLAND OVER THE SE US FROM FLORIDA TO
NORTH CAROLINA.

HURRICANE IKE IS CENTERED NEAR 23.2N 62.7W AT 05/1500 UTC OR
ABOUT 370 NM NORTH OF THE LEEWARD ISLANDS AND ABOUT 480 NM
EAST-NORTHEAST OF GRAND TURK ISLAND MOVING W AT 14 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 954 MB. MAXIMUM SUSTAINED WIND SPEED
IS 105 KT WITH GUSTS TO 130 KT. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
IKE IS A DANGEROUS CATEGORY THREE HURRICANE ON THE SAFFIR-
SIMPSON HURRICANE SCALE. NORTHERLY UPPER WINDS HAVE PRODUCED
SHEAR OVER IKE THUS WEAKENING IT SLIGHTLY. THIS SHEAR IS
EXPECTED TO DECREASE IN ABOUT 24 HOURS AND IKE IS EXPECTED TO
STRENGTHEN AGAIN IN FOLLOWING COUPLE DAYS. SCATTERED MODERATE/
STRONG CONVECTION IS FROM 20N-24N BETWEEN 61W-65W WITH SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 17N-24N BETWEEN
60W-65W INCLUDING THE LEEWARD AND VIRGIN ISLANDS.

TROPICAL STORM JOSEPHINE IS CENTERED NEAR 15.8N 34.8W AT 05/1500
UTC OR ABOUT 600 NM WEST OF THE SOUTHERNMOST CAPE VERDE ISLANDS
MOVING WNW AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003
MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. STRONG SOUTHERLY UPPER
WINDS HAVE COMPLETELY EXPOSED THE LOW LEVEL CENTER OF JOSEPHINE
WITH NO REMAINING DEEP CONVECTION. THIS SHEAR IS EXPECTED OVER
THE AREA FOR THE NEXT COUPLE OF DAYS THEN WEAKEN. THEREFORE IF
THE LOW CENTER REMAINS INTACT...JOSEPHINE COULD RESTRENGTHEN AT
THAT TIME. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
ARE FROM 14N-19N BETWEEN 32W-38W.

...TROPICAL WAVES...

TROPICAL WAVE IS OVER THE CAPE VERDE ISLANDS ALONG 23W S OF 19N
MOVING W 10-15 KT. THIS WAVE IS JUST FAR ENOUGH E OF T.S.
JOSEPHINE TO NOT HAVE EFFECT ON THIS WAVE. WEAK INVERTED-V
CURVATURE IS OBSERVED ON SATELLITE IMAGERY WITH A SMALL AREA OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER THE NORTHERN
MOST CAPE VERDE ISLANDS FROM 16N-18N BETWEEN 23W-26W AND S OF
THE CAPE VERDE ISLANDS FROM 11N-12N BETWEEN 24W-26W.

TROPICAL WAVE IS ALONG 53W S OF 15N MOVING W NEAR 10-15 KT. WAVE
REMAINS LOW AMPLITUDE AND HAS SLOWED OVER THE PAST 24 HOURS.
WAVE IS EMBEDDED WITHIN AN ACTIVE PART OF THE ITCZ BUT DOES NOT
EXHIBIT THE TYPICAL INVERTED PATTERN.

...THE ITCZ...

THE ITCZ AXIS IS ANALYZED ALONG 17N16W 15N28W 12N44W 9N62W...
DISRUPTED BY THE TWO TROPICAL WAVE AND T.S. JOSEPHINE. CLUSTERS
OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 8N-13N
BETWEEN 43W-49W AND FROM 10N-14N BETWEEN 49W-57W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LONGWAVE TROUGH IS OVER THE US INTO THE NW GULF
WITH A STATIONARY FRONT ENTERING THE GULF ALONG THE CENTRAL
MISSISSIPPI COAST ACROSS THE MISSISSIPPI DELTA OF LOUISIANA
EXTENDING SW TO JUST S OF BROWNSVILLE TEXAS. THE FRONT W OF 94W
IS BEGINNING TO WEAKEN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
ARE WITHIN 120 NM SE OF THE FRONT. A WEAK INVERTED UPPER TROUGH
EXTENDS FROM THE COAST OF S MEXICO IN THE CENTRAL BAY OF
CAMPECHE NW ALONG THE COAST TO NEAR TAMPICO MEXICO. A SURFACE
TROUGH EXTENDS FROM 26N91W TO THE E BAY OF CAMPECHE NEAR 20N92W.
UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS/
THUNDERSTORMS WITHIN 120 NM ALONG THE COAST OF MEXICO FROM
VERACRUZ TO JUST N OF TAMPICO. AN MID/UPPER TROUGH IS IN THE SE
GULF FROM FLORIDA BAY TO A WEAK UPPER LOW JUST N OF THE YUCATAN
CHANNEL. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
ARE OVER THE FLORIDA PENINSULA AND COULD DRIFT INTO THE FAR E
GULF COMPLIMENTS OF T.S. HANNA. THE FRONT IS EXPECTED TO
DISSIPATE BY SAT WITH A WEAK HIGH PRESSURE BUILDING OVER THE N
GULF DURING THE FIRST OF THE WORK WEEK AS HANNA MOVES OUT OF THE
REGION TONIGHT/SAT MORNING.

CARIBBEAN SEA...
BROAD UPPER LEVEL RIDGE DOMINATES THE CARIBBEAN ANCHORED IN THE
CENTRAL ATLC E OF T.S. HANNA WITH THE UPPER TROUGH OVER THE SE
GULF OF MEXICO COVERING THE FAR NW CARIBBEAN. ISOLATED SHOWERS
AND POSSIBLE ISOLATED THUNDERSTORMS DOT THE W/CENTRAL CARIBBEAN
W OF A LINE FROM SW HAITI ALONG 12N78W TO THE COAST OF COSTA
RICA/NICARAGUA AND S OF A LINE FROM CENTRAL CUBA NEAR 21N79W
ACROSS THE CAYMAN ISLANDS TO THE YUCATAN PENINSULA JUST N OF
BELIZE. STRONG SUBSIDENCE AND DRY AIR ARE PUSHING ACROSS THE
CARIBBEAN E OF 74W CLEARING THE REMAINDER OF THE CARIBBEAN WITH
THE EXCEPTION OF THE LEEWARD/VIRGIN ISLANDS WHERE THERE IS
ACTIVITY ASSOCIATED WITH HURRICANE IKE.

ATLANTIC OCEAN...
TWO TROPICAL STORMS AND ONE HURRICANE ARE LOCATED IN THE
DISCUSSION AREA...SEE SPECIAL FEATURES ABOVE FOR DETAILS. A
BROAD UPPER RIDGE COVERS THE W ATLC ANCHORED E OF T.S. HANNA
NEAR 29N71W AND EXTENDING S OVER THE CARIBBEAN. UPPER DIFFLUENCE
TO THE E IS GENERATING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 60
NM OF 69W BETWEEN 28N-32W. A SHEAR AXIS EXTENDS FROM THE E ATLC
NEAR THE MADEIRA ISLANDS ALONG 32N29W THEN SW TO AN UPPER LOW
CENTERED NEAR 19N45W CONTINUING OVER THE TROPICS TO 15N47W.
UPPER DIFFLUENCE TO THE S IS ENHANCING THE CONVECTION ASSOCIATED
WITH THE ITCZ. THE TYPICAL E/W UPPER RIDGE EXTENDS FROM OFF
AFRICA ALONG 22N TO 40W AND S OF THE SHEAR AXIS. ADDITIONAL AT
THE SURFACE IS A BROAD SURFACE RIDGE COVERING THE AREA N OF 20N
E OF 55W AND N OF 30N E OF 70W ANCHORED N OF THE REGION. HANNA
IS EXPECTED TO MOVE OUT OF THE REGION TONIGHT/SAT MORNING WITH
IKE EFFECTING THE TURKS AND CAICOS BY SAT NIGHT/SUN.

$$
WALLACE


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