[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON 18 APR 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
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N0 10N09W 8N13W 5N20W 2N40W EQ50W.
SCATTERED MODERATE/STRONG CONVECTION HAS DEVELOPING S OF THE
AXIS OVER BURKINA FASO AND THE IVORY COAST FROM 5N-10N BETWEEN
0W-9W.  WIDELY SCATTERED MODERATE CONVECTION IS S OF THE AXIS
BETWEEN 29W-40W.

...DISCUSSION...

GULF OF MEXICO...
A 1027 MB HIGH IS CENTERED NEAR THE GEORGIA/FLORIDA BORDER AND
COVERS THE ENTIRE GULF OF MEXICO REGION AS WELL AS THE ERN THIRD
OF MEXICO. THE RIDGE IS PRODUCING MAINLY LIGHT/MODERATE E/SE
WINDS OVER THE AREA... INCREASING MOISTURE VALUES ACROSS NE
MEXICO AND MUCH OF TX. A CUT-OFF MID/UPPER LOW SPINNING IN THE
MID WESTERN UNITED STATES CONTINUES TO DRAG A TROF SW ACROSS
TEXAS AND NRN MEXICO INTO THE WESTERN GULF OF MEXICO.  THIS TROF
IS TAPPING INTO MOISTURE AND PRODUCING WIDELY SCATTERED SHOWERS/
TSTMS PRIMARILY N OF 23N INTO TX W OF 94W. SHOWERS/TSTMS WILL
CONTINUE TO DEVELOP OVER S/SE TX THRU TONIGHT AS THE SHORTWAVE
SWINGS TO THE E.  SHOWERS/TSTMS WILL BEGIN TO SHIFT EASTWARD
OVER THE E GULF AND FLORIDA WED AND THU AS THE SYSTEM SKIRTS OFF
THE E COAST.

CARIBBEAN...
AN OLD DISSIPATING FRONTAL TROF HAS BEGUN TO PUSH SLOWLY
WESTWARD AND IS NOW ALONG A LINE FROM HISPANIOLA SW TO JUST OFF
THE COAST OF JAMAICA NEAR 17N77W THEN TO THE COAST OF COSTA
RICA.  UPPER LEVEL WINDS CONTINUES TO BE SPLIT IN A CLASSIC
SHEAR AXIS OVER THE NW CARIBBEAN FROM JAMAICA TO NICARAGUA.
THIS IS PRODUCING ENOUGH LOW-LEVEL CONVERGENCE FOR WIDELY
SCATTERED SHOWERS/ISOLATED TSTMS TO DEVELOP UP TO 150 NM N OF
THE AXIS...SOME OF WHICH HAVE BEEN OCCASIONALLY AFFECTING PARTS
OF HISPANIOLA...JAMAICA...AND COASTAL NICARAGUA. THE UPPER
LEVELS ARE DOMINATED BY MOSTLY SWLY FLOW SE OF A LINE FROM THE
WINDWARD PASSAGE TO NICARAGUA.  SHOWERS WILL CONTINUE TO AFFECT
THE W CARIBBEAN AT LEAST FOR THE NEXT 24 HRS AS THE SFC BOUNDARY
SLOWLY DISSIPATES...BUT AREAS FARTHER NE FROM HISPANIOLA TO
PUERTO RICO COULD STILL SEE VERY SHOWERY WEATHER INTO THE
WEEKEND.

ATLANTIC...
SFC HIGH PRES CONTINUES TO BUILD FROM WEST TO EAST OFF THE
U.S. COAST. A BROAD UPPER LEVEL LONGWAVE TROF IS SLOWLY MOVING
OVER THE W ATLC WATERS...STRETCHING ALONG A LINE FROM 32N58W TO
THE S/CNTRL BAHAMAS...BUT A SHORTWAVE DISTURBANCE NEAR BERMUDA
IS TRANSFERRING SOME MOMENTUM TO THIS FEATURE AND CONTINUES TO
PUSHING IT TO THE E. A COLD FRONT EXTENDS INTO THE AREA ALONG
32N52W 25N60W TO THE N COAST OF THE DOMINICAN REPUBLIC...WITH
SCATTERED MODERATE CONVECTION WITHIN 100 NM OF THE BOUNDARY N OF
25N AND SCATTERED SHOWERS/TSTMS UP TO 75 NM N OF THE BOUNDARY S
OF 24N.  A STRONG 1026 MB SUBTROPICAL HIGH CENTERED NEAR 31N32W
DOMINATES THE REMAINDER OF THE ATLC. A RIDGE EXTENDS SW TO
19N55W...BUT THE WEATHER IN SOME PARTS OF THE E ATLC IS BEING
AFFECTED BY THE FEATURES IN THE MID/UPPER LEVELS. A STATIONARY
CUT-OFF MID/UPPER LOW IS LOCATED NEAR 22N33W WITH A TROF
EXTENDING SW TO 5N40W AND IS DRAWING A GOOD AMOUNT OF HIGH
CIRRUS NWD OFF THE COAST OF AFRICA BETWEEN 16W-30W. THE LOW WILL
DRIFT EWD TO THE COAST OF AFRICA THROUGH FRIDAY...AND SHOULD
THEN BEGIN TO BRING SOME OF THE HIGH CIRRUS INLAND OVER
SENEGAL...MAURITANIA...AND WESTERN SAHARA.

$$
JP/MF





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