[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 080000
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU JUL 07 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 19.0N 76.6W OR ABOUT 90 MILES
SE OF CABO CRUZ CUBA...AND 125 MILES SW OF GUANTANAMO CUBA...
MOVING NW 13 KT. MAXIMUM SUSTAINED WIND IS 100 KT GUSTS TO 120
KT...MAKING DENNIS A STRONG CATEGORY 3 HURRICANE ON THE
SAFFIR-SIMPSON SCALE. ESTIMATED MINIMUM CENTRAL PRESSURE
REPORTED BY AN AIR FORCE HURRICANE HUNTER IS 957 MB. SEE 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. DENNIS HAS A SMALL 9 NM
DIAMETER EYE.  ENVIRONMENTAL CONDITIONS REMAIN QUITE FAVORABLE
FOR STRENGTHENING AND THE OFFICIAL FORECAST SHOWS A BORDERLINE
CATEGORY 4 HURRICANE IN 12 HOURS.  DENNIS IS EXPECTED TO WEAKEN
SOMEWHAT OVER CUBA...BUT IT SHOULD REGAIN STRENGTH WHEN IT
EMERGES OVER THE SOUTHEASTERN GULF OF MEXICO.  PRESENTLY
NUMEROUS STRONG CONVECTION IS IN THE VICINITY OF THE EYE FROM
17N-20N BETWEEN 75W-79W TO INCLUDE JAMAICA.  SCATTERED MODERATE
CONVECTION IS SPIRAL BANDS EXTEND FROM 15N-21N BETWEEN 70W-80W
TO INCLUDE WESTERN HISPANIOLA...AND E CUBA WHERE LOCALIZED
FLOODING IS OCCURRING ESPECIALLY OVER HIGHER TERRAIN.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE IS ALONG 37W MOVING W 10-15 KT.
SATELLITE IMAGERY INDICATES A FAINT NOTCH IN THE STRATOCUMULUS
FIELD N IF 15N.  THERE IS ALSO A NWD SURGE OF SAHARAN DUST TO
THE E OF THE AXIS. THIS POSITION MATCHES WELL WITH THE GFS 700
MB WIND/VORTICITY FIELD. WIDELY SCATTERED MODERATE CONVECTION IS
ALONG THE ITCZ FROM 7N-12N BETWEEN 31W-36W.

CENTRAL ATLANTIC TROPICAL WAVE IS ALONG 56W S OF 20N MOVING W
10-15 KT. THE CAYENNE UPPER AIR SOUNDING SHOWED A WELL-DEFINED
WAVE PASSAGE LAST NIGHT...SO IT SEEMS WE FINALLY HAVE A BETTER
HANDLE ON ITS POSITION.  ISOLATED MODERATE CONVECTION IS ALONG
THE ITCZ FROM 8N-12N BETWEEN 52W-60W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N17W 10N25W 10N37W 5N45W 5N55W.
IN ADDITION TO CONVECTION MENTIONED WITH TROPICAL WAVES...
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 10N-13N BETWEEN
25W-29W.  ISOLATED MODERATE CONVECTION IS FURTHER S FROM 6N-10N
BETWEEN 22W-29W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE TROUGH IS OVER THE CENTRAL GULF OF MEXICO ALONG
28N86W 25N93W.  ISOLATED SHOWERS ARE WITHIN 30 NM OF THE
TROUGH.  SCATTERED MODERATE CONVECTION IS OVER W CUBA FROM
21N-23N BETWEEN 81W-85W MOVING W.  THE REMAINDER OF THE GULF HAS
MOSTLY FAIR SKIES.  IN THE UPPER LEVELS...AN ANTICYCLONIC
CIRCULATION IS CENTERED OVER N FLORIDA NEAR 29N80W.  A CYCLONIC
CIRCULATION IS CENTERED OVER THE YUCATAN PENINSULA NEAR 21N90W.
BOTH UPPER LEVEL SYSTEMS HAVE MODERATE TO STRONG SUBSIDENCE
ENHANCING THE FAIR WEATHER IN THE GULF.  CONDITIONS WILL BEGIN
TO DETERIORATE OVER THE SE GULF ON FRI AS WINDS INCREASE TO
TROPICAL STORM STRENGTH DURING THE AFTERNOON WITH NUMEROUS
SHOWERS/TSTMS SPIRALING FROM E TO W IN THE OUTER SQUALLS OF
HURRICANE DENNIS. HURRICANE CONDITIONS ARE EXPECTED TO SPREAD
ACROSS THE E/CNTRL GULF WATERS FRI EVENING THROUGH SUN...WITH A
POTENTIAL LANDFALL ALONG THE NE/CNTRL GULF COAST.

CARIBBEAN...
SEE SPECIAL FEATURES FOR DISCUSSION ON HURRICANE DENNIS. AN
UPPER LEVEL RIDGE HAS BUILT TO THE E OF DENNIS OVER THE E
CARIBBEAN AS HIGH LEVEL CIRRUS SPREADS FROM NW TO SE OVER THE
NRN LEEWARD ISLANDS. MOISTURE IS RELATIVELY SCARCE E OF ABOUT
70W AS DRY SAHARAN AIR HAS SPREAD W OF THE LESSER ANTILLES IN
THE WAKE OF DENNIS. CURRENTLY SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS OVER N COLOMBIA WITHIN 30 NM OF 11N73W.
SCATTERED MODERATE TO STRONG CONVECTION IS INLAND OVER EL
SALVADOR AND S GUATEMALA FROM 13N-16N BETWEEN 88W-94W.  MORE
SCATTERED CONVECTION WILL BEGIN TO SPREAD OVER THE WINDWARD
ISLANDS TONIGHT WITH THE APPROACH OF A TROPICAL WAVE.

ATLANTIC...
A 1016 MB LOW IS OVER THE CENTRAL ATLANTIC NEAR 32N54W.  A COLD
FRONT EXTENDS SW TO 28N57W 28N62W.  SCATTERED SHOWERS ARE WITHIN
30 NM OF THE FRONT.  A STRONG 1029 MB HIGH IS LOCATED N OF THE
AZORES ISLANDS NEAR 43N27W.  HIGH PRESSURE DOMINATES THE
ATLANTIC N OF 20N AND E OF 50W.  IN THE UPPER
LEVELS...ANTICYCLONIC CIRCULATION IS N OF22N AND W OF 74W OVER
THE W ATLANTIC.  A CYCLONIC CIRCULATION IS CENTERED FURTHER E AT
27N69W.  ANOTHER CYCLONIC CIRCULATION IS NE OF THE LEEWARD
ISLANDS NEAR 22N56W.  A VERY LARGE RIDGE IS OVER W AFRICA AND
THE E ATLANTIC FROM 5N-30N E OF 50W.  E/W RIDGE AXIS IS ALONG
18N.

$$
FORMOSA





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