[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271034
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED 27 OCT 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED ABOUT 925 NM E OF THE LESSER ANTILLES
ALONG 45W S OF 17N MOVING W NEAR 15 KT. A SHARP AND WELL-DEFINED
LOW-LEVEL CIRCULATION IS IDENTIFIED ALONG THE WAVE AXIS BUT MOST
OF THE ASSOCIATED SHOWERS/CLOUDINESS IS EAST AND SOUTH OF THE
STRONGEST ROTATION. SCATTERED MODERATE CONVECTION FROM 7N-13N
BETWEEN 41W-47W.

TROPICAL WAVE MOVING ACROSS THE ABC ISLANDS ALONG 68W/69W S OF
16N MOVING W 10-15 KT. THE WAVE HAS A GENERALLY LOW AMPLITUDE
WITH A NARROW LINE OF SHOWERS EXTENDING E/W ACROSS THE E
CARIBBEAN WATERS. THIS LINE IS PARTIALLY DUE TO A DISSIPATING
FRONTAL BOUNDARY THAT EXTENDS ACROSS THE LEEWARD ISLANDS INTO
THE CNTRL ATLC. SHOWERS/TSTMS ARE BECOMING MORE SCATTERED FROM
14N-17N BETWEEN 65W-71W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 14N10W 9N20W 8N30W 6N47W 9N70W
7N80W. A LARGE AREA OF SCATTERED MODERATE CONVECTION...LEFTOVER
FROM A WEST AFRICAN SQUALL LINE...HAS MOVED OFF THE COAST FROM
3N-7N BETWEEN 9W-16W. WIDELY SCATTERED TO SCATTERED MODERATE
WITHIN 120 NM OF THE AXIS BETWEEN 19W-32W. SCATTERED MODERATE
EXTENDING FROM LAKE MARACAIBO TO NW COLOMBIA. WIDELY SCATTERED
MODERATE N OF THE AXIS PRIMARILY ALONG THE CARIBBEAN COAST OF
PANAMA AND COSTA RICA.

...DISCUSSION...

GULF OF MEXICO...
AN ELONGATED SFC RIDGE EXTENDS DOWN THE EASTERN SEABOARD OF THE
UNITED STATES NUDGING SWD ACROSS FLORIDA AND THE E GULF OF
MEXICO. A WEAK 1023 MB HIGH IS CENTERED OVER E/CNTRL GEORGIA
WITH GENERALLY LIGHT E/SE FLOW CIRCULATING THROUGH THE GULF. AN
EXPANSIVE UPPER LEVEL HIGH IS CENTERED OVER THE CNTRL GULF NEAR
26N89W AND MODERATE/STRONG SUBSIDENCE WITHIN 300/400 NM IS
PRODUCING LIMITED CLOUDINESS AND FAIR WEATHER. A SMALL MID/UPPER
LOW IS CENTERED IN THE VICINITY OF MEXICO CITY BUT MOST OF THE
SHOWERS/TSTMS ACROSS SRN PARTS OF MEXICO HAVE DISSIPATED DURING
THE OVERNIGHT HOURS.

CARIBBEAN...
THE SOUTHERN PERIPHERY OF A BROAD SFC RIDGE OVER THE GULF OF
MEXICO BARELY POKES INTO THE NW PART OF THE CARIBBEAN BASIN
WHILE TROUGHING EXTENDS TO THE E OF HISPANIOLA. IN THE UPPER
LEVELS...A TROF IS SINKING INTO THE AREA FROM THE DOMINICAN
REPUBLIC SWWD TO 13N80W THEN AS A SHEAR LINE ACROSS NICARAGUA.
BROAD N FLOW BEHIND THIS TROF IS USHERING IN DRY MID/UPPER LEVEL
AIR OVER THE W/CNTRL CARIBBEAN AND KEEPING THE AREA SHOWER-FREE
DOWN TO ABOUT 12N. FARTHER E...MOISTURE IS BEING PULLED NWD
AHEAD OF THE TROF AND STREAMS ACROSS MOST OF THE E CARIBBEAN
WATERS AND LESSER ANTILLES. SHOWERS/TSTMS ARE BECOMING MORE
SCATTERED OVER THE E CARIBBEAN NEAR A TROPICAL WAVE AND REMNANT
SFC TROUGH WHICH EXTENDS ALONG 15N67W 22N54W...WITH OTHER
CONVECTIVE ACTIVITY EXTENDING FROM ABOUT GUADELOUPE NEWD OVER
THE ATLC WATERS.

ATLANTIC WEST OF 50W...
THE SAME UPPER TROF WHICH IS DRAPED ACROSS THE CARIBBEAN IS
STATIONED OVER THE W ATLC ALONG 32N60W 20N70W WITH DRY AND
STABLE AIR FEEDING SWD JUST TO THE E OF THE BAHAMAS. THE AIR IS
COOL AND MOIST ENOUGH IN THE LOWER LEVELS TO PRODUCE A LAYER OF
STRATOCUMULUS EXTENDING S OF THE GULF STREAM BETWEEN 67W-78W TO
THE N BAHAMAS. FARTHER E...A COMPLEX MULTI-LOW SYSTEM IS
CENTERED NE OF BERMUDA WITH A REMNANT SFC TROF DRAGGING
SWD INTO THE SUBTROPICAL WATERS. THE TROF DEMARCATES A LINE
ALONG 30N54W 24N60W 23N69W WITH TWO WEAK 1005 MB LOWS NEAR
30N56W AND 29.5N61W. ISOLATED SHOWERS ARE WITHIN 60 NM OF THE
TROF N OF 29N AND INTERMITTENT SHOWERS HAVE DEVELOPED NEAR THE
WESTERNMOST LOW. A SECOND TROF...OR MORE OF A CONVERGENCE
LINE...EXTENDS NE OF GUADELOUPE ALONG 16N62W 22N54W WITH
SCATTERED MODERATE CONVECTION E OF THE NRN LEEWARD ISLANDS FROM
15N-20N BETWEEN 58W-62W.

ATLANTIC EAST OF 50W...
EXTENSIVE SFC HIGH PRES EXTENDS ACROSS THE SUBTROPICAL/TROPICAL
ATLC BETWEEN AFRICA AND 50W WITH A 1020 MB HIGH CENTERED NEAR
25N33W. IN ADDITION...AN ELONGATED UPPER RIDGE IS LOCATED E/NE
OF THE LESSER ANTILLES ALONG 12N57W 30N32W. FARTHER E...A POTENT
MID/UPPER LOW IS TUMBLING WWD OVER THE TROPICAL ATLC NEAR
14N39.5W AND IS UNDERCUTTING THE RIDGE...AND A TROF/SHEAR AXIS
EXTENDS NEWD TO 22N30W 25N20W 23N10W. MODERATE/STRONG SUBSIDENCE
EXTENDS UP TO 400 NM W OF THE LOW/TROF AND HAS PRODUCED FAIR
WEATHER JUST TO THE E OF THE ISLANDS. AMPLIFYING RIDGING TO THE
E OF THE LOW IS ENHANCING UPPER DIFFLUENCE TO THE SW OF THE CAPE
VERDE ISLANDS WITH A LARGE AREA OF SCATTERED MODERATE CONVECTION
FROM 8N-16N BETWEEN 29W-36W. ELSEWHERE...MOSTLY DRY WEATHER
COVERS THE E ATLC EXCEPT FOR AN AREA OF WIDELY SCATTERED
MODERATE CONVECTION TO THE N OF THE SUBTROPICAL RIDGE FROM
28N-31N BETWEEN 29W-39W.

$$
BERG








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