[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 272352
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU OCT 27 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...

TROPICAL STORM BETA CENTERED NEAR 11.9N 81.4W...OR 45 NM SSE OF
SAN ANDRES ISLAND AND 140 NM E OF BLUEFIELDS NICARAGUA...AT
28/0000 UTC MOVING N 3 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
997 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 50
KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC AND THE PUBLIC ADVISORY UNDER HEADERS
MIATCPAT1/WTNT31 FOR MORE DETAILS. AFTER A BRIEF WARMING OF
CLOUD TOPS SINCE ABOUT 2000 UTC...DEEP CONVECTION HAS ONCE AGAIN
BEGUN TO BURST NEAR THE CENTER WITH CLOUD TOP TEMPERATURES TO
-90C. THE CONVECTIVE PATTERN SUGGESTS A CENTRAL DENSE OVERCAST
WITH ONE PRIMARY SPIRAL BAND EXTENDING NW AND N OFF THE
NICARAGUAN COAST. AN IMPRESSIVE OUTFLOW JET EXTENDS N OF BETA
INTO THE SWLY FLOW AHEAD OF THE MID-LATITUDE TROUGH OVER THE
GULF OF MEXICO...AND FAIR OUTFLOW EXTENDS SW ACROSS PANAMA AND
COSTA RICA. SCATTERED MODERATE/STRONG CONVECTION FROM 10N-14N
BETWEEN 80W AND THE COAST OF NICARAGUA. SCATTERED MODERATE ALSO
FROM 14N-17N BETWEEN 76W-82W. BETA IS EXPECTED TO MOVE SLOWLY N
AND W OVER THE NEXT FEW DAYS...POSSIBLY COMING MOVING ONSHORE
INTO NICARAGUA DURING THE WEEKEND. TEN TO FIFTEEN INCHES OF RAIN
ARE EXPECTED IN PARTS OF COSTA RICA...HONDURAS...NICARAGUA...AND
THE ISLANDS OF SAN ANDRES AND PROVIDENCIA DUE TO THE SLOW
MOVEMENT OF BETA.

...TROPICAL WAVES...

CENTRAL ATLANTIC TROPICAL WAVE ALONG 40W S OF 16N MOVING W 10-15
KT. A 1008 MB LOW IS ANALYZED ALONG THE WAVE AXIS NEAR 8N40W. A
WEAK CIRCULATION IS NOTED IN SATELLITE IMAGERY BUT ADJACENT
CONVECTION IS MEAGER AND DISORGANIZED. ISOLATED SHOWERS/TSTMS
FROM 7N-14N BETWEEN 38W-44W.

TROPICAL WAVE CROSSING THE LEEWARD AND WINDWARD ISLANDS ALONG
62W S OF 19N MOVING W 10-15 KT. AS OF 8 AM EDT...UPPER AIR DATA
FROM BARBADOS AND GUADELOUPE INDICATED THAT THE WAVE WAS BETWEEN
THOSE TWO ISLANDS...SO IT IS MOVED TO 62W BY EXTRAPOLATION. THE
WAVE WAS ALSO BEING TRACKED ALONG A CLUSTER OF SHOWERS/TSTMS
OVER THE FAR SW CARIBBEAN BUT MUCH OF THIS ACTIVITY HAS SINCE
WEAKENED. WIDELY SCATTERED MODERATE CONVECTION IS FROM 11N-17N
BETWEEN 60W-68W...EXTENDING ACROSS THE WINDWARD ISLANDS AND
TOWARDS THE OFFSHORE VENEZUELAN ISLANDS.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 74W S OF 18N MOVING W 10
KT. THE WAVE HAS DECELERATED ITS FORWARD MOVEMENT AS IT
APPROACHES THE CIRCULATION OF T.S. BETA OFF OF NICARAGUA.
SCATTERED MODERATE CONVECTION HAS DEVELOPED NEAR THE AXIS FROM
10N-17N BETWEEN 71W-75W...AFFECTING THE GUAJIRA PENINSULA OF
COLOMBIA.

...ITCZ...

ITCZ AXIS IS ALONG 5N10W 5N27W 14N39W...THEN ALONG 6N42W
15N60W...THEN FROM 10N78W SW ACROSS PANAMA. SCATTERED MODERATE
CONVECTION MOVING OFF THE AFRICAN COAST FROM 1N-12N BETWEEN
9W-15W. ISOLATED SHOWERS/TSTMS FROM 6N-12N BETWEEN 26W-36W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP POSITIVELY-TILTED MID-LATITUDE TROUGH RESTS OVER THE
EASTERN HALF OF THE UNITED STATES AND REACHES WELL INTO THE GULF
OF MEXICO TO 20N. A SHORTWAVE IS DROPPING DOWN INTO THE BASE OF
THE TROUGH FROM WRN TENNESSEE INTO N TEXAS AND IS INTERACTING
WITH LOW-LEVEL MOISTURE FURTHER S TO TRIGGER SCATTERED SHOWERS/
TSTMS N OF 22N BETWEEN 95W-100W FROM CNTRL TEXAS TO NEAR TAMPICO
MEXICO. THE ATMOSPHERE IS MORE SUBSIDENT E OF 90W AND IS
RESTRICTING TSTM DEVELOPMENT OVER THE E GULF AND FLORIDA. WEAK
HIGH PRES HAS SETTLED IN ACROSS THE AREA BUT THERE ARE A FEW
WEAK SURFACE TROUGHS EMBEDDED WITHIN THE FLOW. A 1017 MB LOW IS
S OF PENSACOLA FLORIDA NEAR 27N86W WITH A TROUGH EXTENDING SW TO
24N87W AND IS PRODUCING PATCHY CLOUDS FROM 23N-30N BETWEEN
84W-88W. MOST OF THE GULF WILL REMAIN DRY OVER THE COMING DAYS
EXCEPT OVER S TEXAS AND NE MEXICO WHERE MOISTURE WILL CONTINUE
TO BE POOLED AGAINST THE E SLOPES OF THE SIERRA MADRES. THIS
WILL PRODUCE ISOLATED SHOWERS/TSTMS MAINLY NEAR THE COAST.

CARIBBEAN...
SEE SPECIAL FEATURES FOR DISCUSSION ON T.S. BETA. DEEP MOISTURE
LIES ACROSS MOST OF THE CARIBBEAN BASIN EXCEPT FOR A BIT OF
DRIER AIR WHICH HAS MADE ITS WAY ACROSS THE FAR NW CARIBBEAN BY
WAY OF THE GULF OF MEXICO UPPER TROUGH. THE SUBTROPICAL JET
LYING E OF THE TROUGH IS DRAWING UPPER LEVEL MOISTURE OUT OF THE
AREA NEWD ACROSS CUBA AND THE BAHAMAS. AN UPPER HIGH IS CENTERED
S OF HISPANIOLA NEAR 15N71W WITH DEEP EASTERLY FLOW TO ITS SE
BRINGING MORE MOISTURE WWD ACROSS THE LESSER ANTILLES. ASIDE
FROM CONVECTION ASSOCIATED WITH BETA AND THE TWO TROPICAL
WAVES...THE TAIL END OF A FRONTAL BOUNDARY EXTENDS ACROSS E CUBA
TO NEAR JAMAICA AND IS HELPING TO TRIGGER SCATTERED MODERATE
CONVECTION FROM 16N-21N BETWEEN 74W-82W...EXTENDING FROM HAITI
TO THE CAYMAN ISLANDS.

WEST ATLANTIC...
THE SUBTROPICAL JET EXTENDS FROM W/CNTRL CUBA AND ANDROS ISLAND
NEWD TO 32N71W AND LIES PARALLEL TO A SURFACE STATIONARY FRONT
EXTENDING FROM E CUBA NEWD TO 26N70W 32N57W. ISOLATED
SHOWERS/TSTMS LIE WITHIN 325 NM NW OF THE FRONT...WITHIN THE
BAND OF HIGH LEVEL MOISTURE...AND THE SRN END OF THE BOUNDARY
HAS BEGUN TO SLOWLY LIFT BACK TO THE NW ACROSS THE BAHAMAS. A
WEAK 1016 MB LOW IS LOCATED JUST OFF THE GEORGIA COAST WITH A
SURFACE TROUGH EXTENDING SWD OFF THE FLORIDA COAST TO THE UPPER
KEYS. HOWEVER...THE SUBSIDENCE ASSOCIATED WITH THE GULF OF
MEXICO UPPER TROUGH IS PREVENTING SHOWER/TSTM DEVELOPMENT ALONG
THIS BOUNDARY.

EAST/CENTRAL ATLANTIC...
A MASSIVE UPPER LEVEL HIGH IS CENTERED OVER THE CNTRL ATLC NEAR
27N43W WITH ITS CIRCULATION SPANNING N OF 16N INTO THE N ATLC
AND BETWEEN 20W-64W. AN UPPER LEVEL LOW IS MOVING WWD S OF THE
HIGH NEAR 8N54W AND IS ASSOCIATED WITH A SMALL AREA OF DRIER AIR
WHICH IS MOVING INLAND ACROSS NRN SURINAME AND GUYANA...AND IS
HEADING W TOWARDS THE WINDWARD ISLANDS AND NE VENEZUELA.
CONVERSELY...DIFFLUENCE S AND E OF THE LOW IS PRODUCING
SCATTERED MODERATE CONVECTION OVER FRENCH GUIANA AND ERN
SURINAME...AND MORE ISOLATED SHOWER ACTIVITY NEAR THE ITCZ
BETWEEN 40W-53W. FARTHER E...A SHARP UPPER TROUGH EXTENDS FROM
32N14W TO 20N23W WITH AN ASSOCIATED COLD FRONT FROM 32N15W
23N25W 20N39W. MAINLY HIGH/MID LEVEL CLOUDS EXTEND 400 NM SE OF
THE FRONT N OF 20N BUT THERE COULD BE EMBEDDED AREAS OF ISOLATED
SHOWERS OR DRIZZLE INCLUDING NEAR THE CANARY ISLANDS AND
MOROCCO. A SECOND NEARLY STATIONARY UPPER TROUGH EXTENDS FROM
THE COAST OF MAURITANIA NEAR 18N16W SW TO 12N30W WITH A PLUME OF
TROPICAL MOISTURE EXTENDING UP TO 400 NM S OF THE AXIS.

$$
BERG


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