[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212333
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON APR 21 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL
ANALYSIS...WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 3N5W 3N21W 4N40W 3N52W. A SECOND
ITCZ AXIS IS SOUTH OF THE EQUATOR WITH THE MOST CONVECTIVE
ACTIVITY. SCATTERED MODERATE/STRONG CONVECTION IS INLAND OVER W
AFRICA MOVING OFF THE COAST OF LIBERIA AND SIERRA LEONE.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM THE ITCZ AXIS TO THE EQUATOR BETWEEN 25W-31W AND WITHIN 90
NM OF THE ITCZ AXIS BETWEEN 34W-45W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LOW IS OVER E NORTH CAROLINA WITH A NARROW UPPER TROUGH
EXTENDING OVER THE FAR E GULF AND THE FLORIDA PENINSULA. A
SURFACE LOW IS OFF THE CAROLINA COAST WITH A SURFACE TROUGH
EXTENDING THROUGH THE W ATLC INTO THE GULF OVER THE FLORIDA KEYS
ALONG 25N86W TO 28N91W. SCATTERED SHOWERS AND CLUSTERS OF
ISOLATED THUNDERSTORMS ARE WITHIN 60 NM OF THE SURFACE TROUGH.
OTHERWISE A BROAD UPPER RIDGE DOMINATES THE GULF ANCHORED IN THE
E PACIFIC REGION EXTENDING AN AXIS THROUGH THE BAY OF CAMPECHE
TO THE COAST NEAR THE LOUISIANA/TEXAS BORDER. A WEAK 1017 MB
HIGH REMAINS N OF THE SURFACE TROUGH NEAR 28N87W. SOUTHERLY
SURFACE FLOW OVER THE W GULF IS BANKING SOME LOW LEVEL CLOUDS
ALONG THE COAST OF W LOUISIANA AND TEXAS. OTHERWISE THE
REMAINDER OF THE GULF IS QUIET THIS AFTERNOON.

CARIBBEAN SEA...
A BROAD UPPER TROUGH IN THE CENTRAL ATLC DIPS S OVER THE NE
CARIBBEAN FROM HISPANIOLA TO OVER THE LEEWARD ISLANDS WHILE THE
REMAINDER OF THE CARIBBEAN IS DOMINATED BY UPPER WESTERLY FLOW
GENERATED BY THE E/W UPPER RIDGE FROM THE TROPICS. MODERATE
EASTERLY TRADE WINDS COVER THE AREA RESULTING FROM THE WEAK
PRESSURE GRADIENT OVER THE ATLC WATERS. AFTERNOON SHOWERS/
THUNDERSTORMS HAVE GENERATED OVER JAMAICA AND PORTIONS OF
HISPANIOLA AND ARE DRIFTING OVER THE IMMEDIATE COASTAL WATERS.
HOWEVER WITH THE STRONG SUBSIDENCE AND DRY AIR THAT DOMINATES
THE CARIBBEAN...THIS ACTIVITY WILL DIMINISH LATER THIS EVENING.

ATLANTIC OCEAN...
A NARROW UPPER TROUGH COVERS THE FAR W ATLC TO OVER FLORIDA WITH
THE UPPER LOW OVER E NORTH CAROLINA AND A 1010 MB LOW OFF THE
CAROLINA COAST AND A SURFACE TROUGH EXTENDING INTO THE REGION
NEAR 32N75W S OVER THE N BAHAMA ISLANDS NEAR 26N78W THEN INTO
THE GULF OF MEXICO ACROSS THE FLORIDA KEYS. A SECOND SURFACE
TROUGH EXTENDS FROM THE SURFACE LOW ALONG 30N78W TO A DEVELOPING
SURFACE LOW ALONG THE COAST OF FLORIDA NEAR DAYTONA BEACH.
SECOND UPPER TROUGH IS OVER THE CENTRAL ATLC EXTENDING S TO 17N
BETWEEN 53W-68W INCLUDING THE NE CARIBBEAN. A SURFACE TROUGH
ASSOCIATED WITH THIS FEATURE EXTENDS FROM 31N52W ALONG 26N56W TO
22N62W. A LARGE UPPER RIDGE IS TO THE E GENERATING ENOUGH UPPER
DIFFLUENCE TO ENHANCE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
COVERING THE AREA N OF 22N FROM 51W-58W. JUST TO THE W OF THIS
UPPER TROUGH IS A MID LEVEL LOW NEAR 26N61W AND SURFACE
REFLECTION IN THE FORM OF A SURFACE TROUGH EXTENDING FROM 28N62W
26N63W TO 24N62W. ISOLATED SHOWERS/THUNDERSTORMS FROM 26N-28N
BETWEEN 60W-63W. AN UPPER RIDGE IS OVER THE E/CENTRAL ATLC WITH
THE AXIS ALONG 42W WITH A WEAK UPPER TROUGH OVER THE FAR E ATLC
EXTENDING FROM THE CANARY ISLANDS THROUGH 25N18W TO 20N26W. A
LARGE SURFACE RIDGE DOMINATES THE E ATLC N OF 18N E OF 50W
ANCHORED BY A 1024 MB HIGH NEAR 30N30W...THUS FAIR WEATHER SKIES
OVER THE AREA E OF 50W. THE TYPICAL E/W UPPER RIDGE AXIS EXTENDS
ACROSS THE TROPICS AND INTO THE CARIBBEAN.

$$
WALLACE


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