[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 010558
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT OCT 1 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 UTC (0315 FOR GOES 12).

...SPECIAL FEATURES...

TROPICAL DEPRESSION NINETEEN IS NEAR 12.3N 32.9W...OR 660 MILES
WSW OF THE CAPE VERDE ISLANDS...AT 01/0300 UTC MOVING NW 2 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS.  A HUGE BURST OF TSTMS IS EXPLODING RELATIVELY
CLOSE TO THE APPARENT CENTER AND THE DEPRESSION APPEARS TO BE
CLOSE TO STORM STATUS.  SCATTERED MODERATE TO STRONG CONVECTION
FROM 10N-13N BETWEEN 31W-35W WITH MORE ISOLATED ACTIVITY
ELSEWHERE WITHIN 180 NM OF THE CENTER IN THE NE QUADRANT.

1006 MB LOW IS LOCATED OVER THE NW CARIBBEAN NEAR 19N85W MOVING
WNW ABOUT 5 KT.  PRESSURES HAVE BEEN SLOWLY FALLING NEAR THE LOW
AND A BURST OF CONVECTION IS WITHIN 75 NM OF THE CENTER.  THE
LOW HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE WITHIN 36
HOURS OR SO BEFORE IT MOVES OVER YUCATAN.  AN UPPER LOW IS NW OF
THE SURFACE LOW... SOMEWHAT HINDERING ITS DEVELOPMENT BUT ALL
MODELS SUGGEST THIS UPPER FEATURE WILL FADE WITH TIME.

...TROPICAL WAVES...

E ATLC WAVE ADDED ALONG 19W S OF 20N MOVING W 10 KT.  LONG-TERM
SATELLITE LOOPS SHOW THE WAVE LEAVING W AFRICA YESTERDAY AND
ONLY SLOWLY MOVING WESTWARD.  ISOLATED MODERATE CONVECTION IS
WITHIN 120 NM BEHIND THE WAVE AXIS FROM 11N-15N.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 72W S OF 23N MOVING W
15-20 KT. THE WAVE IS NEXT TO IMPOSSIBLE TO FIND AT NIGHT WITH
CIRRUS MASKING ANY LOW-LEVEL WAVE SIGNATURE.  THERE IS NO CLEAR
TSTM PATTERN EITHER AS ISOLATED MODERATE CONVECTION IS SPECKLED
ACROSS THE REGION FROM 15N-18N BETWEEN 69W-76W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 11N14W 6N21W 9N29W 8N35W 10N42W
11N49W INTO A WEAK 1011 MB LOW NEAR 15N56W.  SCATTERED MODERATE
CONVECTION IS WITHIN 75 NM OF THE AXIS BETWEEN 41W-50W.
ISOLATED MODERATE FROM 3N-15N BETWEEN 25W-30W AND WITHIN 75 NM
OF 4N20W.  A LINE OF TSTMS IS WITHIN 45 NM OF 11N15W 12N18W.
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF 17N56W.

...DISCUSSION...

GULF OF MEXICO...
DRY AIR ALOFT CONTINUES OVER ALMOST THE ENTIRE GULF REGION AND
THE CLOSEST DEEP-LAYERED MOISTURE IS BEING KEPT AT BAY OVER THE
YUCATAN CHANNEL.  A FEW TSTMS FORMED ON THE AFTERNOON SEABREEZE
ON THE W COAST OF FLORIDA.. LEADING TO SOME ISOLATED ACTIVITY
NEAR 26.5N82.5W.  OTHERWISE A WEAK UPPER LOW SITS JUST N OF THE
YUCATAN CHANNEL NEAR 22N87W DRIFTING SLOWLY W AND HAS ALLOWED
SOME OF THIS CARIBBEAN MOISTURE TO BE TAPPED...BRINGING IT JUST
OVER CUBA TOWARDS THE STRAITS OF FLORIDA AND ENHANCING A FEW
SHOWERS NEAR THE FLORIDA KEYS. ELSEWHERE...THE STATIONARY FRONT
HAS DISSIPATED OVER NORTHERN GULF WATERS WITH A FEW CLOUDS N OF
THE REGION IN THE REMNANTS OF THE BOUNDARY.   A SMALL 1010 MB
LOW IS MOVING SW 10-15 KT OVER THE W GULF WATERS NEAR 25N94W
WITH ISOLATED SHOWERS AND A TSTMS OR TWO WITHIN 90 NM OF THE
CENTER.  ISOLATED SHOWERS ARE IN THE BAY OF CAMPECHE ABOUT 250
NM SW OF THE LOW MOST LIKELY DUE TO AN UPPER TROUGH WHICH IS
SITTING ALONG THE MEXICAN COAST.  THE GFS SUGGESTS THAT A SLUG
OF MOISTURE FROM S FLORIDA WILL MOVE WESTWARD RAPIDLY ACROSS THE
GULF.. AFFECTING S TEXAS BY EARLY MON.

CARIBBEAN...
AN UPPER LEVEL HIGH CENTERED NEAR THE CAYMAN ISLANDS AND AN
UPPER LOW NE OF THE LEEWARD ISLANDS ARE PRODUCING STRONG NLY
SHEAR OVER A GOOD CHUNK OF THE AREA.  EARLIER TSTMS HAVE MOSTLY
DISSIPATED BUT A FEW REMAIN FROM THE YUCATAN PENINSULA EWD TO
HISPANIOLA AND PUERTO RICO WITH CIRRUS OUTFLOW BLOWN SWD TOWARDS
SOUTH AMERICA. A 1006 MB LOW...AS DESCRIBED IN SPECIAL
FEATURES...IS NEAR 19N85W AND HAS A BURST OF CONVECTION OVER IT
THIS MORNING.  THE SYSTEM IS IN BETWEEN THE LOWEST SHEAR AREA TO
THE SOUTH AND THE UPPER LOW TO THE NW.  THE E CARIBBEAN AND
LESSER ANTILLES...E OF ABOUT 67W...ARE UNDER THE SUBSIDENT
REGIME OF THE UPPER LOW NE OF THE AREA AND ITS TRAILING TROUGH
AXIS THAT EXTENDS TO ISLA MARGARITA...SO SKIES ARE MAINLY CLEAR
AND WINDS ARE GENERALLY LIGHT.  WETTER-THAN-AVERAGE CONDITIONS
ARE LIKELY IN THE W CARIBBEAN FOR THE NEXT COUPLE DAYS WHILE
MOSTLY DRY WEATHER CONTINUES IN THE E CARIBBEAN.

ATLANTIC WEST OF 50W...
AN UPPER LEVEL TROUGH AXIS IS LOCATED OVER THE W ATLC WATERS
FROM 31N76W TO 29N81W AND IS ASSISTING SHOWERS N OF 29N W OF
70W.  OTHERWISE AN AREA OF UPPER DIFFLUENCE TO THE SE HAS BEEN
PRODUCING SCATTERED SHOWERS/TSTMS E OF THE BAHAMAS FROM 21N-26N
BETWEEN 66W-71W. PLENTIFUL MOISTURE IS ALSO ACROSS THE BAHAMAS
WITH WIDELY SCATTERED SHOWERS/TSTMS THROUGHOUT THE BAHAMAS. W
ATLC UPPER LOW IS LOCATED NEAR 21N61W AND IS KICKING OFF
ISOLATED TSTMS FROM 18N-26N BETWEEN 55W-62W. THE UPPER
LOW/TROUGH HAS CREATED LIGHT WINDS E OF THE LESSER ANTILLES AND
AN EXTREMELY DIFFUSE ITCZ.

ATLANTIC EAST OF 50W...
A STRONG UPPER HIGH IS IN THE MIDDLE OF THE ATLC NEAR 16N45W AND
CONNECTS TO A RIDGE EXTENDING TO T.D. NINETEEN THEN EWD TO THE
COAST OF AFRICA NEAR GUINEA. UPPER DIFFLUENCE JUST S OF THE
RIDGE AXIS IS ALLOWING A LINEAR AREA OF CONVECTION TO DEVELOP
ALONG THE ITCZ...AND SIGNIFICANT OUTFLOW TO THE S OF THE T.D.
NINETEEN. A VIGOROUS UPPER LOW IS CENTERED WSW OF THE CANARY
ISLANDS NEAR 25N28W AND HAS PRODUCED A 1014 MB LOW AT THE
SURFACE NEAR 23N28W. WIDELY SCATTERED MODERATE CONVECTION HAS
FORMED NEAR THE SFC LOW FROM 23.5N-27N BETWEEN 25W-29W ALTHOUGH
ISOLATED SHOWERS ARE ALSO EMBEDDED WITHIN THE CIRCULATION OF THE
UPPER LOW WITHIN 300 NM. FARTHER E...A SHARP UPPER RIDGE AXIS
LIES ACROSS NW AFRICA AND UPPER DIFFLUENCE IS PRODUCING ISOLATED
TSTMS OVER AND WITHIN 60 NM S OF THE CANARY ISLANDS FROM A DEEP
POOL OF MOISTURE. THIS ACTIVITY MAY PERSIST FOR ANOTHER 24 HRS
OR SO BEFORE A MORE TYPICAL NE FLOW DEVELOPS AND DRIES OUT THE
ATMOSPHERE.

$$
BLAKE

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