[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 061744
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU APR 06 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1615 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N10W 3N24W 2N40W...THE EQUATOR AT
45W 1S52W. SCATTERED MODERATE TO STRONG CONVECTION FROM 1N TO 7N
BETWEEN 8W AND 14W.  SCATTERED SHOWERS AND TSTMS ELSEWHERE
WITHIN 90 EITHER SIDE OF THE ITCZ AXIS.

...DISCUSSION...

GULF OF MEXICO...
HIGH AMPLITUDE MIDDLE TO UPPER LEVEL RIDGE DOMINATES THE PATTERN
ALOFT OVER THE GULF EXTENDING FROM A ANTICYCLONE OVER THE BAY OF
CAMPECHE NWD OVER THE MISSISSIPPI VALLEY OF THE UNITED STATES.
AN UPSTREAM TROUGH IS OBSERVED ADVANCING EWD OVER THE WESTERN TO
CENTRAL UNITED STATES BUT NEARLY ALL OF THE ASSOCIATED
DYNAMICS/LIFT ARE CONFINED N OF THE AREA.  ATTENDANT COLD FRONT
IS PUSHING SWD DOWN THE E SLOPES OF THE ROCKIES AND SIERRA MADRE
MOUNTAINS AND IS EXPECTED TO MOVE INTO THE NW GULF FRI NIGHT
INTO EARLY SAT.  STILL...THE FRONT WILL INITIALLY LACK
APPRECIABLE MOISTURE AND SHOWER/TSTMS ACTIVITY IS EXPECTED TO BE
LIMITED OVER THE W GULF.  SOME LOW LEVEL MOISTURE POOLING ALONG
THE BOUNDARY AS IT REACHES THE EXTREME E GULF AND FLORIDA MAY
PRODUCE SOME SHOWERS/TSTMS LATE SAT OR SUN. ELSEWHERE AT THE
SURFACE...STRONG LOW PRES OVER THE CENTRAL U.S. IS PRODUCING
MODERATE RETURN FLOW OVER THE W GULF WITH LIGHT AND VARIABLE
WINDS OVER THE E GULF WATERS.

CARIBBEAN SEA...
MIDDLE TO UPPER LEVEL TROUGH OVER THE W ATLC TRAILS SWD OVER
CUBA INTO THE W CARIBBEAN. CONFLUENT FLOW INTO THE BASE OF THE
TROUGH IS PRODUCING STRONG SUBSIDENCE AND VERY DRY/STABLE
CONDITIONS ALOFT GENERALLY W OF A LINE FROM COSTA RICA TO
HISPANIOLA. E OF THE SAME LINE...A 60-110 KT SUBTROPICAL JET
EXTENDS FROM JUST S OF HISPANIOLA NEWD OVER THE LEEWARD ISLANDS
AND INTO THE CENTRAL ATLC.  DIFFLUENCE ALONG THE JET AXIS IS
PRODUCING A CANOPY OF HIGH CLOUDINESS ACROSS MUCH OF THE E
CARIBBEAN AND LESSER ANTILLES.  AT THE LOWER LEVELS...THE
REMNANTS OF AN OLD FRONTAL BOUNDARY EXTENDING FROM THE NE
CARIBBEAN INTO THE CENTRAL ATLC IS PRODUCING SCATTERED SHOWERS
AND A FEW TSTMS N OF 15N E OF 65W INCLUDING THE LEEWARD ISLANDS
N OF DOMINICA...THE VIRGIN ISLANDS...AND PUERTO RICO.  THE
TROUGH AND ASSOCIATED MOISTURE IS EXPECTED TO REMAIN
QUASI-STATIONARY OVER THE NEXT DAY OR TWO WHILE THE UPPER TROUGH
ADVANCES SLOWLY EWD.  THIS COMBINATION WILL KEEP UNSETTLED
CONDITIONS ACROSS THE NE CARIBBEAN WITH SCATTERED SHOWERS/TSTMS
EXPECTED TO CONTINUE THROUGH FRI.  AT THE SURFACE...THE ATLANTIC
SUBTROPICAL RIDGE REMAINS QUITE WEAK WITH TRADES RUNNING BELOW
NORMAL THROUGHOUT THE CARIBBEAN. THE SUBTROPICAL RIDGE WILL
REBUILD OVER THE ATLC LATE FRI AND SAT WITH GRADUALLY INCREASING
TRADES.

ATLANTIC...
AN UPPER LEVEL TROUGH-RIDGE-TROUGH PATTERN PREVAILS OVER THE
ATLANTIC WITH A TROUGH OVER THE W ATLC FROM THE CANADIAN
MARITIMES SWD TO CUBA....RIDGE OVER THE CENTRAL ATLC ROUGHLY
ALONG 50W...AND A TROUGH OVER THE E ATLC FROM THE AZORES SWD TO
JUST NW OF THE CAPE VERDE ISLANDS. THE BULK OF THE ACTIVE
WEATHER REMAINS FOCUSED OVER THE CENTRAL ATLC WHERE DIFFLUENT
FLOW ALOFT E OF THE W ATLC TROUGH IS SPARKING A LINE OF
SCATTERED SHOWERS/TSTMS ALONG A WEAKENING COLD FRONT FROM 32N60W
28N63W.  ACTIVITY BECOMES MORE ISOLATED ALONG THE REMAINDER OF
THE WEAKENING FRONTAL BOUNDARY TO 27N72W.  A SECOND AREA OF
SCATTERED SHOWERS/TSTMS IS LOCATED FURTHER S ALONG AN OLD
REMNANT FRONTAL TROUGH EXTENDING FROM THE NE CARIBBEAN TO 22N45W
IN THE ATLANTIC. THE STRONGEST AND MOST NUMEROUS OF THIS
ACTIVITY IS LOCATED 150-450 NM N OF PUERTO RICO FROM 21N-24N
BETWEEN 62W-65W.  THE OVERALL PATTERN WILL ADVANCE EWD DURING
THE NEXT 24 HOUR WITH THE BEST CHANCE OF SHOWERS/TSTMS BEING N
OF 18N BETWEEN 45W AND 55W BY FRI EVENING.  ELSEWHERE OVER THE
ATLANTIC WATERS...CONFLUENT FLOW AND SUBSIDENCE IS OBSERVED IN
WATER VAPOR IMAGERY OVER THE W ATLC W OF A LINE FROM HISPANIOLA
TO BERMUDA AND E ATLANTIC E OF A 45W. A WEAK FRONTAL BOUNDARY
DROPPING SWD INTO THE E ATLC LATER TODAY AND TONIGHT MAY PRODUCE
A FEW ISOLATED SHOWERS.  OTHERWISE...GENERALLY TRANQUIL
CONDITIONS ARE EXPECTED TO CONTINUE.  FINALLY...VISIBLE
SATELLITE IMAGERY SHOWS A LOW-LEVEL TROUGH MOVING WESTWARD ALONG
45W GENERALLY S OF 15N. HOWEVER...THE FEATURE IS EMBEDDED WITHIN
A LARGE AREA OF DRY/STABLE AIR AND DUST ASSOCIATED WITH A SAL.
AS SUCH...IT IS ONLY ABLE TO PRODUCE CONVECTION WITHIN THE
ITCZ.

$$
RHOME


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