[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 190554
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SAT 19 FEB 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ...
ITCZ AXIS ALONG 5N10W 2N20W 1N40W EQ50W.  SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 1N-3N BETWEEN 17W-19W...FROM
EQ-2N BETWEEN 21N-26W...AND FROM 2S-5N BETWEEN 36W-47W.
SCATTERED MODERATE CONVECTION IS FROM 2N-4N BETWEEN 25W-29W.

...DISCUSSION...
GULF OF MEXICO...
UPPER LEVELS...VERY BROAD RIDGING...ALMOST ZONAL FLOW...
DOMINATES FORECAST AREA FROM MEXICO ACROSS GULF. ABUNDANT
TROPICAL MOISTURE PLUME ADVECTED BY STRONG JETSTREAM OF OVER 100
KT ACROSS NW MEXICO INTO W TEXAS AND HENCE EWD INTO N GULF
STATES N OF 28N.  STRONG SUBSIDENCE COVERS GULF OF MEXICO S OF
29N EXCEPT SWATH FROM 23N TO 25N WHERE DISSIPATING COLD FRONT
LIES.

AT THE SURFACE...1027 MB HIGH PRES OVER N LOUISIANA/ALABAMA AT
32N91W.  WEAK COLD FRONT ACROSS CENTRAL GULF OF MEXICO FROM
STRAITS OF FLORIDA TO E MEXICO NEAR TAMPICO DRIFTING S WHILE
DISSIPATING.  GRADIENT N OF FRONT SLACKING AS HIGH PRES WEAKENS
FOR LACK OF UPPER SUPPORT AND QUASI-ZONAL FLOW OVER RIDGE.
BROKEN LOW CLOUDS AND WIDELY SCATTERED SHOWERS ALONG FRONT
DECREASING AS SUBSIDENCE ALOFT MAKES ITS WAY TO THE SURFACE.
AREA OF LOW LEVEL CLOUDS AND SCATTERED SHOWERS OVER SW BAY OF
CAMPECHE RESULT FROM DAMMING OF LOW LEVEL MOISTURE ALONG FRONT.
CLOUDS ALONG E EDGE OF SIERRA MADRE FROM 18N-23N W OF 95W SHOULD
DECREASE NEXT 24 HOURS AS FRONTAL BOUNDARY DISSIPATES AND
SUBSIDENCE TAKES OVER.

CARIBBEAN...
WELL ANCHORED MID/UPPER LEVEL RIDGE REMAINS IN PLACE ALONG N
COAST OF S AMERICA TO YUCATAN PENINSULA.  STRONG SUBSIDENCE
UNDER RIDGE COVER ENTIRE CARIBBEAN BASIN WITH LITTLE VERTICAL
DEVELOPMENT OF CLOUDS MAINLY OVER SW CORNER WHERE STRONG SURFACE
WINDS CONVERGE ON MOUNTAINS OVER COSTA RICA.  HIGH PRES RIDGE
BUILDING SWD FROM GULF OF MEXICO TIGHTENED GRADIENT OVER
CARIBBEAN WITH INCREASING E TRADES.  LOW LEVEL MOISTURE AND
SHOWERS TO REMAIN SPARSE THROUGH WEEKEND PRIOR TO ARRIVAL SUN
NIGHT OF DIFFUSE FRONTAL BOUNDARY NOW OVER NE CARIBBEAN.

ATLANTIC...
PREDOMINATELY ZONAL FLOW OVER SW N ATLANTIC N OF 20N AND W OF
50W.  COLD FRONT ENTERS W ATLANTIC E OF OF BERMUDA ALONG 32N56W
AND EXTENDS SW TO 26N70W AND TO STRAITS OF FLORIDA AT 23N80W.
LACK OF UPPER SUPPORT DUE TO ZONAL FLOW ALOFT WEAKENS FRONT
WITHIN NEXT 36 HRS.  NARROW CLOUD LINE WITH ISOLATED SHOWERS
ALONG LEADING EDGE OF FRONT.  OVER CENTRAL ATLC...MIDDLE TO
UPPER LEVEL SHORTWAVE TROUGH ALONG 39W PRODUCING CLOUDINESS AND
SCATTERED SHOWERS/THUNDERSTORMS N OF 18N FROM 20W-40W.  ACTIVITY
SHOULD DECREASE NEXT 24 HOURS AS SHORTWAVE IS FORCED NE OUT OF
AREA BY LARGER STRONGER LONGWAVE TROUGH.  OVER E ATLANTIC AND W
AFRICA...MID/UPPER LEVEL TROUGH N OF 20N E OF 25W.  ON THE
SURFACE...1040 MB HIGH PRES AT 48N24W CAUSING OVERCAST COLD AIR
STRATOCUMULUS CLOUDS AND SCATTERED AREAS OF RAIN OFF COAST OF W
AFRICA N OF 26N E OF 36W.  FURTHER S...LARGE BUBBLE OF AFRICAN
DUST S AND E OF CAPE VERDE ISLANDS EXTEND TO ITCZ.

$$
WALLY BARNES

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