[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 100013
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUL 09 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING
INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER
OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURE...

HURRICANE DENNIS IS CENTERED NEAR 26.1N 84.9W AT 2300 UTC MOVING
NW 12 KT.  THIS POSITION IS ABOUT 285 MILES SOUTH OF PANAMA CITY
FLORIDA AND ABOUT 385 MILES SOUTHEAST OF BILOXI MISSISSIPPI.
MAXIMUM SUSTAINED WINDS ARE 90 KT GUSTING TO 110 KT WITH A
MINIMUM CENTRAL PRESSURE OF 947 MB.  SEE THE LATEST NHC PUBLIC
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC AND THE
FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS.  THE CENTRAL PRESSURE FOR DENNIS HAS PLUMMETED
IN THE PAST THREE HOURS.  REDEVELOPMENT LOOKS VERY IMPRESSIVE.
VERY LITTLE SHEAR IS OVER THE SYSTEM...SEA SURFACE TEMPERATURES
ARE WARM...AND CONVECTION IS OVER ALL QUADRANTS.  EYE DIAMETER
IS NOW 15 NM MILES.  A VERY DANGEROUS HURRICANE NOW LURKS IN THE
GULF OF MEXICO.  LEADING SQUALL LINES ARE ALREADY AFFECTING THE
SE UNITED STATES FROM SOUTH CAROLINA TO MISSISSIPPI AND ARE
INTERACTING WITH A STATIONARY FRONT.  MORE FEEDER BANDS ARE OVER
THE FLORIDA PANHANDLE WITH NUMEROUS LIGHTNING...GUSTY
WINDS...AND EMBEDDED TORNADOES.  PRESENTLY NUMEROUS STRONG
CONVECTION IS WITHIN 60 NM OF THE CENTER.  SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION EXTENDS FROM 20N-30N BETWEEN
81W-87W.

...TROPICAL WAVES...

A 1012 MB LOW IS LOCATED OFF THE COAST OF W AFRICA NEAR 11N24W
MOVING W 10-15 KT.  A SWIRL IS NOTED WITH VERY LITTLE DEEP
CONVECTION.

CENTRAL ATLC TROPICAL WAVE IS ALONG 38W S OF 17N MOVING W 10-15
KT WITH A 1012 MB LOW ON THE WAVE NEAR 10.5N.  THIS LOW HAS
BECOME A LITTLE BETTER-ORGANIZED THAN YESTERDAY WITH BANDING
FEATURES COMING ON THE N SIDE AND QUIKSCAT INDICATING A CLOSED
SURFACE CIRCULATION.  CONVECTION IS WIDELY SCATTERED FROM 9N-12N
BETWEEN 38W-41W BUT REMAINS MEAGER AS THE SYSTEM IS ENTANGLED
WITH A LOT OF MID/UPPER DRY AIR.

E CARIBBEAN TROPICAL WAVE IS ALONG 65W S OF 15N MOVING W 10-15
KT.  THE WAVE IS COMBINING WITH A MID/UPPER LEVEL TROUGH TO ITS
WEST TO PRODUCE SCATTERED MODERATE TO ISOLATED STRONG CONVECTION
FROM GUADELOUPE AND N-CENTRAL VENEZUELA BETWEEN 60W-66W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 11N15W 11N38W 7N50W 8N60W. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS ALONG THE COAST OF W
AFRICA FROM 6N-13N BETWEEN 12W-23W.  SCATTERED MODERATE
CONVECTION IS FROM 6N-9N BETWEEN 36W-41W.  WIDELY SCATTERED
MODERATE CONVECTION IS FROM 1N-3N BETWEEN 42W-45W...AND FROM
6N-8N BETWEEN 49W-52W.

...DISCUSSION...

GULF OF MEXICO...
HURRICANE DENNIS DOMINATES THE WEATHER STORY FOR THE EASTERN
GULF OF MEXICO WHILE THE WESTERN GULF HAS A MID/UPPER TROUGH
FROM SE TEXAS SOUTHWARD TO THE BAY OF CAMPECHE.  VERY DRY AIR
ALOFT IS W OF 90W.  ANTICYCLONIC FLOW COVERS THE E GULF AROUND
DENNIS WITH A FAVORABLE ENVIRONMENT FOR MORE INTENSIFICATION.
DENNIS SHOULD CONTINUE MOVING IN A GENERAL NW TO NNW DIRECTION
TOWARD THE CENTRAL GULF COAST BETWEEN THE TROUGH OVER THE W GULF
AND A MID/UPPER RIDGE OVER THE W ATLC.

CARIBBEAN SEA...
EFFECTS FROM DENNIS ARE WANING AS THE CYCLONE PULLS FARTHER AWAY
FROM THE AREA.  HOWEVER VERY HEAVY RAIN CONTINUES FOR W CUBA W
OF 80W CONTINUING SOUTHWARD THRU THE CAYMAN ISLANDS.  THE
HEAVIEST RAIN SHOULD SHIFT INTO EXTREME W CUBA OVERNIGHT THEN
LIFT NORTH BY SUN BRINGING MUCH DRIER CONDITIONS BY LATE IN THE
WEEKEND.  A TROPICAL WAVE IS INTRODUCING MOISTURE OVER THE E
CARIBBEAN E OF 67W MOVING W.  IN THE UPPER LEVELS...ANTICYCLONIC
FLOW ALOFT COVERS THE W AND CENTRAL CARIBBEAN WITH PLENTIFUL
HIGH CLOUDS W OF 70W DUE TO CIRRUS OUTFLOW FROM THE HURRICANE.
FARTHER E...AN ANTICYCLONIC CIRCULATION IS E OF THE WINDWARD
ISLANDS NEAR 12N56W...WHILE A CYCLONIC CIRCULATION IS NE OF THE
LEEWARD ISLANDS NEAR 22N60W.

ATLANTIC OCEAN...
A 1023 MB HIGH IS OVER THE W ATLANTIC NEAR 31N70W.  A WEAK
TROUGH IS OVER THE CENTRAL ATLANTIC ALONG 32N50W 27N57W
SCATTERED SHOWERS ARE WITHIN 60 NM OF THE TROUGH.  A 1026 MB
HIGH N OF THE AZORES IS NEAR 41N26W THAT DOMINATES THE ATLANTIC
N OF 20N AND E OF 45W.  PRESSURES ARE A LITTLE HIGHER THAN
AVERAGE IN THE DEEP TROPICAL ATLC THOUGH THEY ARE A BIT
LESS-THAN-AVERAGE IN THE SUBTROPICS... SUPPORTING A PRESSURE
GRADIENT WEAKER THAN AVERAGE AND ANOTHER DAY OF WEAK TRADE
WINDS.  IN THE UPPER LEVELS...LITTLE CHANGE FROM YESTERDAY WITH
MID/UPPER RIDGING EXTENDING FROM NE FLORIDA TO JUST NW OF
BERMUDA WITH A WEAK TROUGH BENEATH THE RIDGE FROM PUERTO RICO TO
26N71W. OUTFLOW FROM DENNIS COVERS THE BAHAMAS AND THE REST OF
THE SW ATLC SW OF A LINE FROM HISPANIOLA TO N GEORGIA.  A
CYCLONIC CIRCULATION IS CENTERED NEAR 22N60W AND EXTENDS A
TROUGH TO THE VIRGIN ISLANDS.  MODERATE/STRONG SUBSIDENCE COVERS
THE CENTRAL ATLC W OF 40W TO THE TROUGH AXIS BETWEEN 10N-30N.  A
BROAD TROUGH IS AT THE NORTHERN FRINGE OF THE CENTRAL ATLC FROM
25N45W TO 31N30W THOUGH NOT PRODUCING ANY SIGNIFICANT WEATHER.
THE TYPICAL AFRICAN ANTICYCLONE IS OVER WESTERN SAHARA NEAR
22N16W WITH RIDGE AXIS WSW TO 14N52W.  INVERTED TROUGH IS ALONG
40W S OF 18N CREATING A SMALL BREAK IN THE RIDGE.  ELY FLOW IS A
BIT DIFFLUENT S OF THE RIDGE.. SUPPORTING TSTMS NEAR THE
TROPICAL WAVE ALONG 38W AND THE FAR E ATLC ITCZ.

$$
FORMOSA




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