[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT 30 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED JUST E OF BARBADOS ALONG 59W S OF 20N
MOVING W NEAR 10 KT WITH A WEAK 1012 MB LOW NEAR 18N. THE WAVE
CONTINUES TO DECELERATE AS IT MOVES INTO A BROAD AREA OF LOW
PRESSURE ASSOCIATED WITH A DEEP LAYERED TROUGH AND ASSOCIATED
STATIONARY FRONT OVER THE CENTRAL ATLC.  GOOD UPPER LEVEL
DYNAMICS ASSOCIATED WITH THE UPPER TROUGH PRODUCED AN IMPRESSIVE
BURST OF DEEP CONVECTION NEAR THE WAVE OVERNIGHT BUT THIS
ACTIVITY HAS SINCE MOVED EWD WITH THE UPPER TROUGH.  THE
TROPICAL WAVE IS NOW NEAR THE BASE OF THE UPPER TROUGH RESULTING
IN STRONG SHEAR AND LIMITED CONVECTION.

TROPICAL WAVE LOCATED OVER THE W CARIBBEAN NEAR 80W/81W S OF 19N
MOVING W NEAR 10 KT. THE WAVE IS LOCATED IN BETWEEN A WEAKENING
MIDDLE TO UPPER LEVEL TROUGH FROM THE WINDWARD PASSAGE TO
HONDURAS AND A ANTICYCLONE OVER THE SW CARIBBEAN.  THIS PATTERN
IS PRODUCING A BROAD AREA OF DIFFLUENT UPPER LEVEL FLOW AND
SUPPORTING A LARGE AREA OF WIDELY SCATTERED MODERATE CONVECTION
FROM 9N-19N BETWEEN 77W-82W.  HOWEVER...THIS ACTIVITY IS POORLY
ORGANIZED WITH NO SIGNS OF DEVELOPMENT.

...ITCZ...

ITCZ AXIS IS ALONG 13N10W 6N20W 6N40W 9N55W 7N70W 10M80W.
WIDELY SCATTERED MODERATE CONVECTION FROM FROM 3N-8N BETWEEN
10W-20W.  SCATTERED MODERATE CONVECTION FROM 2N-10N BETWEEN
30W-37W.  SCATTERED MODERATE CONVECTION FROM 7N-10N BETWEEN
44W-56W.

...DISCUSSION...

GULF OF MEXICO...
DRY/TRANQUIL WEATHER CONTINUES OVER GLFMEX AND FLORIDA WITH DEEP
LAYERED RIDGING MAINTAINING CONTROL.  THE RIDGE IS ANCHORED BY A
MIDDLE TO UPPER LEVEL ANTICYCLONE OVER THE CENTRAL GLFMEX WITH
AXIS EXTENDING NEWD OVER THE E UNITED STATES.  THIS PATTERN IS
KEEPING UPSTREAM DISTURBANCES CONFINED OVER THE CONUS AND
PRODUCING STRONG SUBSIDENCE OVER THE ENTIRE AREA.  AT THE
SFC...BROAD RIDGE EXTENDS FROM THE W ATLC ACROSS N FLORIDA INTO
THE N GULF ALONG 30N. RETURN FLOW OVER THE W GLFMEX HAS BEGUN TO
INCREASE AHEAD OF A STATIONARY FRONT OVER CNTRL TEXAS.  THE
FRONTAL BOUNDARY WILL STAY JUST N OF THE AREA THROUGH EARLY
MONDAY THEN MOVE OFF THE TEXAS COAST LATE MON INTO TUESDAY.
CONDITIONS ACROSS THE GLFMEX WILL REMAIN DRY THROUGH SUNDAY WITH
CLOUDINESS AND SHOWERS/THUNDERSTORMS DEVELOPING ALONG THE SE
TEXAS COAST SUNDAY NIGHT AND MONDAY AHEAD OF THE APPROACHING
COLD FRONT.

CARIBBEAN...
THE PERSISTENT DEEP LAYERED TROUGHING PATTERN OVER THE CARIBBEAN
THIS PAST WEEK CONTINUES TO SLOWLY BREAK DOWN AS RIDGING BUILDS
NWD FROM SOUTH AMERICA. IN FACT...NUMERICAL GUIDANCE INDICATES
STRONG MIDDLE TO UPPER LEVEL RIDGING DEVELOPING OVER THE W
TWO-THIRDS OF THE CARIBBEAN BY MONDAY. THE FRACTURED MIDDLE TO
UPPER LEVEL TROUGH WHICH BROKE OFF OF A LARGER SCALE
MID-LATITUDE TROUGH CURRENTLY OVER THE CENTRAL ATLC CONTINUES TO
DRIFT WESTWARD AND WEAKEN FROM THE WINDWARD PASSAGE TO HONDURAS.
THIS FEATURE IS PRODUCING BROAD UPPER LEVEL DIVERGENCE OVER THE
CENTRAL AND E CARIBBEAN SEA. AT THE SAME TIME...TWO TROPICAL
WAVES...ONE NEAR 81W AND A SECOND JUST E OF THE LESSER ANTILLES
IS PRODUCING ABUNDANT TROPICAL MOISTURE.  THIS PATTERN IS
SUPPORTING A LARGE AREA OF UNSETTLED WEATHER WITH CLOUDINESS AND
SCATTERED SHOWERS/THUNDERSTORMS COVERING A GOOD CHUNK OF THE
AREA S OF 17N E OF 83W.  THE UNSETTLED PATTERN WILL CONTINUE FOR
THE NEXT 24 HOURS OVER THE E CARIBBEAN AS A TROPICAL WAVE MOVES
INTO THE AREA TONIGHT.  THE NW CARIBBEAN WILL ALSO BECOME
INCREASING STORMY SUNDAY INTO MONDAY AS THE TROPICAL WAVE NEAR
81W ADVECTS INCREASING MOISTURE WESTWARD.

ATLANTIC WEST OF 45W...
LARGE MID/UPPER LEVEL TROUGH NOW COVERS THE ENTIRE W ATLC WATERS
WITH STRONG SUBSIDENCE AND VERY DRY AIR PREVAILING TO THE SE
UNITED STATES COAST. A BROAD SWATH OF DEEP LAYERED MOISTURE
ACCOMPANIES A SUBTROPICAL JET EXTENDING FROM 20N60W NEWD TO
BEYOND 31N45W.  GOOD UPPER LEVEL DYNAMICS NEAR THE ENTRANCE
REGION OF THE JET IS PRODUCING AN AREA OF NUMEROUS MODERATE
CONVECTION FROM 16N-20N BETWEEN 47W-54W. SCATTERED MODERATE
CONVECTION IS OBSERVED ELSEWHERE WITHIN 250 NM AHEAD OF A COLD
FRONT FROM 32N44W 22N56W.  THE SUBTROPICAL JET IS EXPECTED TO
LIFT QUICKLY NEWD TAKING THE BULK OF THE SUPPORTING DYNAMICS AND
ASSOCIATED WEATHER N OF 25N TONIGHT.  HOWEVER...A SHORTWAVE
TROUGH CURRENTLY DROPPING SEWD OVER THE W ATLC AND BAHAMAS WILL
PRODUCE ANOTHER ROUND OF SHOWERS/THUNDERSTORMS S OF 25N BETWEEN
50W-65W SUNDAY.

ATLANTIC EAST OF 45W...
DEEP LAYERED RIDGING CONTINUES TO DOMINATE THE E ATLC WITH AXIS
ALIGNED N/S ALONG 30W.  SEVERAL CUTOFF UPPER LEVEL LOWS TRAPPED
BENEATH THE RIDGE ARE NOTED IN WATER VAPOR IMAGERY BUT REMAIN
MOISTURE STARVED AND UNABLE TO PRODUCE SIGNIFICANT WEATHER.
FARTHER E...A DIGGING LONGWAVE TROUGH EXTENDS FROM SPAIN SW INTO
NW AFRICA WITH ASSOCIATED COLD FRONT TRAILING FROM THE W
SAHARA/MOROCCO BORDER WESTWARD ACROSS THE CANARY ISLANDS.
PATCHES OF LOW CLOUDS AND SCATTERED LIGHT SHOWERS WITHIN 120 NM
AHEAD OF THE FRONT. OVER THE TROPICAL ATLC...THE ENTIRE ITCZ IS
ACTIVE WITH CONVECTION BUT THE MIDDLE TO UPPER LEVEL ENVIRONMENT
REMAINS UNFAVORABLE FOR TROPICAL DEVELOPMENT.

$$
RHOME




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