[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 042320
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI NOV 4 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
2245 UTC.

...TROPICAL WAVES...

CENTRAL ATLANTIC TROPICAL WAVE ALONG 45W S OF 13N MOVING W 15
KT. A LARGE AREA OF CLOUDINESS AND EMBEDDED SHOWERS/TSTMS
EXTENDS ACROSS THE TROPICAL ATLC BETWEEN 30W-50W WHICH IS MAKING
DIFFERENTIATION OF THE TROPICAL WAVES QUITE DIFFICULT. A LARGE
UPPER LOW IS CENTERED NEAR 18N45W AND THE COMMON CONCEPTUAL
MODEL OF VERTICAL SHEAR WOULD INDICATE THAT THE DEEPEST
CONVECTION SHOULD BE LOCATED E OF THE WAVE AXIS. THEREFORE...THE
WAVE IS PLACED ALONG THE WRN EDGE OF THE CONVECTIVE CLUSTER.
WIDELY SCATTERED MODERATE CONVECTION LIES NEAR THE ITCZ FROM
6N-12N BETWEEN 36W-47W.

TROPICAL WAVE CROSSING THE WINDWARD ISLANDS ALONG 62W S OF 14N
MOVING W 15 KT. A LOW-AMPLITUDE AREA OF TSTMS HAS BEEN TRACKED
JUST N OF THE SOUTH AMERICAN COAST FOR THE PAST DAY OR SO AND IS
NOW MOVING ACROSS THE WINDWARD ISLANDS...PARTICULARLY
TRINIDAD...TOBAGO...AND NE VENEZUELA. WIDELY SCATTERED MODERATE
CONVECTION S OF 11N BETWEEN 60W-63W.

WEST CARIBBEAN TROPICAL WAVE ALONG 81W S OF 16N MOVING W 10 KT.
WEAK ROTATION IS NOTED IN THE CLOUD ENVELOPE OVER THE SW
CARIBBEAN AND DEEP CONVECTION HAS BEEN DEVELOPING ALONG A N/S
LINE ABOUT 150 NM E OF THE NICARAGUAN COAST. SCATTERED MODERATE
CONVECTION FROM 8N-18N BETWEEN 76W-85W. SSM/I AND TRMM IMAGERY
INDICATE RAIN RATES NEAR 0.25-0.50" PER HOUR WITH THIS ACTIVITY.

...ITCZ...

ITCZ AXIS IS ALONG 8N10W 6N25W 10N42W 11N60W. NUMEROUS
MODERATE/STRONG CONVECTION EXTENDING FROM LIBERIA THROUGH SIERRA
LEONE FROM 5N-10N BETWEEN 8W-14W. WIDELY SCATTERED MODERATE WITH
EMBEDDED ISOLATED STRONG FROM 3N-9N BETWEEN 21W-31W. SCATTERED
MODERATE FROM 7N-13N BETWEEN 33W-48W.

...DISCUSSION...

GULF OF MEXICO...
A FLAT UPPER TROUGH IS CURRENTLY SWINGING THROUGH THE WESTERN
U.S. AND IS PRIMARILY SUPPORTING ZONAL FLOW ACROSS THE GULF
REGION. THE EXCEPTION IS A REMNANT MID-LEVEL TROUGH EXTENDING
FROM THE FLORIDA PANHANDLE SW TO THE YUCATAN PENINSULA AND
INCREASING SUBSIDENCE OVER THE E GULF AND FLORIDA. A 300 NM WIDE
BAND OF HIGH CLOUDS EXTENDS FROM NE MEXICO NEWD INTO THE
TENNESSEE VALLEY AND WILL ONLY INCREASE CIRRUS COVERAGE ALONG
THE N GULF COAST TONIGHT. OTHERWISE...THE GULF IS ONLY COVERED
BY A FEW LOW/MID LEVEL CLOUDS MOVING FROM S TO N ON THE WRN EDGE
OF AN ATLC RIDGE. MOISTURE IS GRADUALLY ON THE INCREASE AND
SHOULD BECOME MOST CONCENTRATED NEAR THE MEXICAN COAST BY MON OR
TUE.

CARIBBEAN...
THE W HALF OF THE CARIBBEAN REMAINS CONVECTIVELY ACTIVE DUE TO A
TROPICAL WAVE N OF PANAMA AND A WEAKENING SURFACE TROUGH OVER
THE GULF OF HONDURAS. A WEAK UPPER HIGH IS CENTERED NEAR 12N78W
WITH A RIDGE EXTENDING NW TO THE YUCATAN CHANNEL. THIS SLIGHTLY
DIFFLUENT PATTERN IS FOSTERING SCATTERED MODERATE CONVECTION
FROM PANAMA/COSTA RICA NWD TO 17N BETWEEN RIOHACHA COLOMBIA AND
COASTAL AREA OF NICARAGUA AND HONDURAS. WIDELY SCATTERED
SHOWERS/TSTMS ALSO LIE OVER THE NW CARIBBEAN IN ASSOCIATION WITH
THE SFC TROUGH FROM THE CAYMAN ISLANDS WWD TO THE YUCATAN/BELIZE
COAST. FARTHER E...A STRONG UPPER HIGH JUST N OF PUERTO RICO IS
FORCING A MID-LEVEL SURGE OF DRY AIR ACROSS THE E HALF OF THE
CARIBBEAN WITH ONLY ISOLATED TRADE WIND SHOWERS MOVING ACROSS
THE ISLANDS. AN UPPER LEVEL CYCLONIC SHEAR AXIS EXTENDS FROM
15N76W SE ACROSS THE ABC ISLANDS AND NE VENEZUELA AND CONTINUES
TO ADVECT DEEPER MOISTURE ACROSS NRN PARTS OF SOUTH AMERICA...
AND SHIELDING THE AREA FROM THE DRIER AIR TO THE N. THE NRN
PORTION OF THE AREA WILL REMAIN DRY FOR THE NEXT FEW DAYS WITH
THE DEEPEST MOISTURE LYING S OF 13N.

ATLANTIC...
BROAD W/SWLY UPPER FLOW OVER THE W ATLC IS ADVECTING DRY AIR
FROM THE GULF OF MEXICO ACROSS FLORIDA AND THE NRN
BAHAMAS...BOUNDED BY A 65 KT SUBTROPICAL JET EXTENDING FROM
CNTRL CUBA NE TO BERMUDA. A WEAK SHORTWAVE ALONG 70W IS
INFLECTING THE JET AND PRODUCING AN AREA OF UPPER DIFFLUENCE N
OF 23N BETWEEN E OF 68W. THIS IS INTERACTING WITH A STATIONARY
FRONT ALONG 30N AND A SURFACE TROUGH OVER THE SRN BAHAMAS TO
PRODUCE WIDELY SCATTERED SHOWERS/TSTMS FROM 24N-32N BETWEEN
57W-70W. FARTHER E...A LARGE AREA OF DRY AIR LIES 750 NM E OF
THE LESSER ANTILLES JUST AHEAD OF AN UPPER LOW NEAR 18N45W.
BROAD DIFFLUENCE LIES E OF THE LOW AND IS MAINLY DRAWING HIGH
LEVEL CLOUDINESS NWD BETWEEN 30W-42W BUT THERE ARE AREAS OF
EMBEDDED WIDELY SCATTERED SHOWERS 700 NM N OF THE ITCZ BETWEEN
30W-48W. AN UPPER HIGH IS CENTERED JUST SW OF THE CAPE VERDE
ISLANDS AND IS CAUSING THE UPPER LEVEL MOISTURE TO MOVE EWD
TOWARDS THE AFRICAN COAST. A NARROW UPPER TROUGH EXTENDS FROM
SPAIN SW TO WRN SAHARA WITH NLY FLOW DIGGING SWD ACROSS THE
CANARY ISLANDS.

$$
BERG



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