[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON AUG 15 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1732 UTC.

...SPECIAL FEATURE...

HURRICANE IRENE CENTERED NEAR 36.5N 67.2W...OR 515 NM SSW OF
HALIFAX NOVA SCOTIA...AT 15/1500 UTC MOVING NE 10 KT. MAXIMUM
SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE 985 MB. SEE THE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE
DETAILS. IRENE APPEARS TO BE GOING THROUGH A SLIGHT
INTENSIFICATION PHASE WITH VISIBLE SATELLITE IMAGERY SHOWING A
DIMPLE FEATURE FORMING IN THE CENTRAL DENSE OVERCAST...POSSIBLY
THE PRECURSOR TO AN EYE. HOWEVER...THE CONVECTIVE STRUCTURE HAS
NOT NECESSARILY BECOME ANY BETTER ORGANIZED WITH A RAGGED
APPEARANCE ON ITS SRN PERIPHERY. NUMEROUS MODERATE CONVECTION
EXTENDS WITHIN 75 NM OF THE CENTER...EXCEPT 90 NM TO THE E WHERE
A FEW SPIRAL BANDS EXTEND FARTHER OUT.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE TILTED ALONG 9N31W 15N34W 23N36W
MOVING W 10-15 KT. STRONG NELY FLOW ASSOCIATED WITH THE
SUBTROPICAL HIGH IS PUSHING A SURGE OF DRY AIR ACROSS THE NRN
EXTENT OF THE WAVE...WHICH IS CAUSING IT TO TILT SE/NW. THE LOW
WHICH WAS ALONG THE WAVE HAS CONSEQUENTLY SHEARED OUT...POSSIBLY
LOCATED NEAR 13N34W. THERE IS NO DEEP CONVECTION ASSOCIATED WITH
THIS WAVE.

1009 MB LOW...PREVIOUSLY TROPICAL DEPRESSION TEN...IS CENTERED
NEAR 14.7N 49.2W MOVING WNW 5-10 KT. THE LOW-LEVEL CENTER HAS
BEEN EXPOSED ALL MORNING WITH OCCASIONAL BURSTS OF CONVECTION
OCCURRING TO THE N AND E. THE SYSTEM IS ENTERING INTO THE
TERRITORY OF A DEEP UPPER TROF OVER THE LESSER ANTILLES AND SO
IS UNDER STRONG S/SWLY SHEAR. REDEVELOPMENT IS NOT LIKELY UNTIL
THE SYSTEM ESCAPES THE UPPER LOW...WHICH IS EXPECTED TO MEANDER
OVER THE E CARIBBEAN FOR SEVERAL DAYS. WIDELY SCATTERED
SHOWERS/TSTMS FROM 15N-20N BETWEEN 46W-50W AND ALONG THE ITCZ.

CENTRAL CARIBBEAN TROPICAL WAVE IS HELD BACK A COUPLE OF DEGREES
TO ALONG 75W/76W...TILTING BACK INTO THE SRN BAHAMAS...MOVING W
15-20 KT. UPPER AIR DATA FROM SAN JUAN PUERTO RICO SHOWS THAT
THE WAVE PASSED BETWEEN 00Z AND 12Z ON THE 14TH WHICH PLACES IT
NEAR THE WINDWARD PASSAGE BASED ON EXTRAPOLATION. THIS POSITION
MATCHES WELL WITH A CIRCULATION NOTED NEAR THE SRN BAHAMAS AND
THE DEVELOPMENT OF SHOWERS/TSTMS S OF E CUBA AND JAMAICA.
SCATTERED MODERATE CONVECTION FROM 15N-20N BETWEEN 75W-82W.
WIDELY SCATTERED MODERATE BETWEEN E CUBA AND THE CNTRL
BAHAMAS...AND FROM 14N-17N BETWEEN 68W-72W.

TROPICAL WAVE MOVING ACROSS CENTRAL AMERICA ALONG 87W S OF 20N
MOVING W 10-15 KT. SATELLITE IMAGERY SHOWS A LARGE MID-LEVEL
GYRE EXTENDING FROM THE GULF OF HONDURAS TO S OF NICARAGUA.
UPPER AIR DATA FROM SAN JOSE COSTA RICA SHOWS THE WAVE AXIS
PASSING THIS MORNING BETWEEN 00Z AND 12Z...SO THE WAVE'S
POSITION IS HELD BACK A BIT TO ACCOUNT FOR THIS. NUMEROUS
MODERATE CONVECTION EXTENDS FROM THE NW CARIBBEAN SWD TO THE
COAST OF COSTA RICA FROM 10N-20N BETWEEN 81W-87W. ISOLATED TSTMS
ARE ALSO MOVING ONSHORE FROM CHETUMAL TO SRN BELIZE.

...ITCZ...

ITCZ AXIS IS ALONG 12N15W 8N21W 10N31W 8N37W 16N47W...THEN ALONG
12N52W 10N63W. SCATTERED MODERATE CONVECTION MOVING DEVELOPING
OFF THE COASTS OF GUINEA-BISSAU AND SENEGAL FROM 10N-14N BETWEEN
15W-19W. WIDELY SCATTERED SHOWERS/TSTMS WITHIN 120 NM OF THE
AXIS BETWEEN 18W-30W. WIDELY SCATTERED MODERATE WITHIN 200 NM S
OF THE AXIS BETWEEN 37W-48W. SCATTERED MODERATE WITHIN 75 NM OF
THE AXIS BETWEEN 57W-61W.

...DISCUSSION...

GULF OF MEXICO...
THE TWO MID/UPPER LEVEL LOWS OVER THE GULF APPEAR TO HAVE MERGED
AND BECOME ONE ELONGATED CYCLONIC CIRCULATION WHICH EXTENDS FROM
THE BAY OF CAMPECHE NEWD TO NEAR TAMPA BAY FLORIDA. A 50 KT NLY
JET IS BEGINNING TO PLUNGE DOWN THE W SIDE OF THE CIRCULATION
ALONG THE TEXAS/MEXICO COAST AND SHOULD SERVE TO REINFORCE THE
DEPTH OF THE TROF FOR THE NEXT COUPLE OF DAYS. A WEAK RIDGE IS
IN PLACE IN THE LOW LEVELS STRETCHING APPROXIMATELY ACROSS N
FLORIDA INTO SE LOUISIANA. ISOLATED TSTMS ARE EMBEDDED WITHIN
THE BROAD UPPER LEVEL CIRCULATION AND EXTEND WITHIN 180 NM OF
THE N GULF COAST...WITH THE MOST CONCENTRATED CLUSTER HAVING
RECENTLY MOVED OFF THE FL COAST BETWEEN PANAMA CITY AND
PENSACOLA. OTHER ISOLATED SHOWERS/TSTMS EXTEND FROM THE FL KEYS
SW INTO THE BAY OF CAMPECHE WITH ONE PARTICULAR CLUSTER FOCUSED
90 NM ENE OF VERACRUZ MEXICO. CONDITIONS SHOULD DRY OUT A BIT
OVER THE N GULF AS DRY AIR MOVES IN FROM THE E...BUT SHOWERS/
TSTMS WILL BECOME MORE SCATTERED OVER THE BAY OF CAMPECHE
THROUGH THU AS MOISTURE IS ADVECTED IN BY A TROPICAL WAVE OVER
THE NW CARIBBEAN.

CARIBBEAN...
A BROAD UPPER LEVEL HIGH IS CENTERED OVER THE SW GULF OF
HONDURAS NEAR 17N87W AND IS PROVIDING A DIFFLUENT ENVIRONMENT
FOR SCATTERED TSTMS TO DEVELOP WITH THE TRPCL WAVES NEAR 76W AND
87W. IN FACT...THE ENTIRE W CARIBBEAN IS BEGINNING TO FILL IN
WITH CONVECTION AS THE TSTMS ASSOCIATED WITH THE CNTRL CARIB
WAVE BEGIN TO MERGE WITH THE CNTRL AMERICAN CONVECTION. FARTHER
E...AN E/W TROF IS ALIGNED FROM THE DOMINICAN REPUBLIC EWD PAST
THE NRN LEEWARD ISLANDS ALONG 18N WITH MODERATE W/NW UPPER FLOW
HAVING SPREAD ACROSS THE E AND CNTRL CARIBBEAN. ALTHOUGH THE
TROF IS PROVIDING STRONG WLY SHEAR TO THE AREA...IT IS NOT
PULLING IN DRIER AIR FROM THE N AND IS INSTEAD PULLING MOISTURE
EWD FROM THE CONVECTION LOCATED OVER CNTRL AMERICA. MOISTURE IS
EXPECTED TO LINGER OVER THE W CARIBBEAN FOR THE NEXT SEVERAL
DAYS...CONTINUING THE THREAT FOR SHOWERS/TSTMS...WHILE THE E
CARIBBEAN WILL REMAIN UNDER THE DOMAIN OF PREDOMINANTLY DRY
LOW-LEVEL EASTERLY FLOW.

ATLANTIC...
A LARGE UPPER HIGH IS CENTERED OVER THE W ATLC NEAR 30N73W AND
IS PUSHING MAINLY DRY AIR WWD OVER THE BULK OF THE AREA. THE NRN
END OF A TRPCL WAVE WHICH IS MOVING ACROSS THE CNTRL CARIBBEAN
IS BRUSHING THE SRN BAHAMAS AND TRIGGERING SCATTERED TSTMS OVER
THE BAHAMA BANKS. OTHERWISE...THE REMAINDER OF THE AREA W OF 63W
IS UNDER CLEAR SKIES. FARTHER E...AN UPPER LOW IS CENTERED NEAR
33N44W WITH A 1017 MB SFC LOW TO THE W OF THAT NEAR 31N52W. A
TROF EXTENDS SW OF THE SFC LOW TO NEAR 24N58W AND IS PRODUCING
WIDELY SCATTERED SHOWERS/TSTMS FROM 21N-25N BETWEEN 57W-61W. THE
UPPER LOW IS ALSO PRODUCING SCATTERED SHOWERS/TSTMS FROM 26N-33N
BETWEEN 44W-48W. ANOTHER UPPER TROF EXTENDS FROM THE NRN LEEWARD
ISLANDS NE TO NEAR 20N50W AND IS PRODUCING S/SWLY SHEAR ON TOP
FORMER T.D. 10...WHILE ALSO PULLING ITCZ CONVECTION NWD OFF THE
COAST OF GUYANA. THE E ATLC IS DOMINATED BY A LARGE UPPER HIGH
NEAR 24N28W WITH MODERATE SUBSIDENCE CAPPING A SURGE OF AFRICAN
DUST E OF A LINE FROM 11N26W 20N37W 28N37W. A NEW TRPCL WAVE IS
APPROACHING THE AFRICAN COAST FROM THE E AND IS EXPECTED TO MOVE
OFF LATER TONIGHT OR TOMORROW. SHOWERS/TSTMS MAY BEGIN TO SPREAD
OVER THE CAPE VERDE ISLANDS WED NIGHT AND THU.

$$
BERG


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