[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210534
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUN 21 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 29W/30W S OF 11N MOVING W NEAR 20 KT.
BROAD MID LEVEL INVERTED-V CURVATURE IS SHOWN ON SATELLITE
IMAGERY AND THE MIMIC-TPW ANIMATION DEPICTS A MOISTURE SURGE
BETWEEN 27W-32W. THE UPPER LEVEL FLOW IS KEEPING ANY CONVECTION
TO THE W OF THE WAVE AXIS.

TROPICAL WAVE IS IN THE E CARIBBEAN ALONG 68W/69W S OF 20N
MOVING W NEAR 20 KT. SATELLITE IMAGERY SHOWS A BROAD LOW LEVEL
INVERTED-V CURVATURE WITH THE MIMIC-TPW ANIMATION DEPICTS A
MOISTURE SURGE 72W TO THE LESSER ANTILLES. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 14N-18N BETWEEN 67W-73W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N10W 7N25W 5N34W 2N52W. THE ITCZ IS
ACTIVE THIS EVENING W OF THE TROPICAL WAVE WHILE E OF THE WAVE
IS RATHER TRANQUIL. CLUSTERS OF SCATTERED MODERATE/STRONG
CONVECTION ARE FROM THE EQUATOR TO WITHIN 180 NM N OF THE AXIS
BETWEEN 29W-40W AND CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM THE EQUATOR TO WITHIN 180 NM N OF THE
ITCZ BETWEEN 40W-50W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE REMAINS ANCHORED OVER NW MEXICO COVERING THE
FAR W GULF WITH AN UPPER LEVEL SHORTWAVE TROUGH EXTENDING FROM
THE LOWER MISSISSIPPI VALLEY TO THE BAY OF CAMPECHE. AN UPPER
RIDGE ANCHORED IN THE W CARIBBEAN EXTENDS N OVER THE E GULF.
MODERATE SUBSIDENCE ALONG THE MOST OF THE UPPER TROUGH AXIS
MAINTAINING MOSTLY CLEAR CONDITIONS IN THE W GULF. UPPER LEVEL
DIVERGENCE BETWEEN THIS TROUGH AND A RIDGE TO THE SOUTH IS
GENERATING AN AREA OF SCATTERED SHOWERS/THUNDERSTORMS IN MAINLY
IN THE E BAY OF CAMPECHE S OF 21N E OF 93W AND WITHIN 90 NM
ALONG THE NW COAST OF CUBA BETWEEN 81W-85W. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS DOT THE NE GULF BETWEEN 26N29N BETWEEN
83W-89W. A WEAK PRESSURE PATTERN IS PROVIDING LIGHT WINDS ACROSS
THE REGION.

CARIBBEAN...
AN UPPER RIDGE COVERS THE W CARIBBEAN ANCHORED BY AN UPPER HIGH
INLAND OVER HONDURAS AND EXTENDS N INTO THE GULF OF MEXICO. AN
UPPER TROUGH FROM THE W/CENTRAL ATLC EXTENDS ACROSS THE GREATER
ANTILLES NEAR THE MONA PASSAGE TO JUST OFF THE COLOMBIAN COAST.
MODERATE/STRONG SUBSIDENCE BETWEEN THE UPPER TROUGH AND RIDGE IS
KEEPING THE CENTRAL CARIBBEAN RELATIVELY CLOUD FREE. THE TIGHTER
PRESSURE GRADIENT BETWEEN THE SURFACE RIDGE OVER THE ATLC AND
THE LOWER PRESSURE OVER SOUTH AMERICA IS PRODUCING MODERATE/
STRONG EASTERLY TRADE WINDS ACROSS THE BASIN WITH THE STRONGEST
WINDS UP TO 30 KT JUST OFF THE COLOMBIAN COAST.

ATLANTIC...
THE BROAD UPPER TROUGH IS OVER THE E US JUST CLIPPING THE NW
PORTION OF THE REGION WITH THE ASSOCIATED FRONTAL BOUNDARY NOT
ENTERING THE REGION. AN UPPER LEVEL TROUGH EXTENDS FROM THE
CENTRAL ATLC NEAR 32N36W SW TO A WEAK UPPER LOW NW OF LEEWARD
ISLANDS THROUGH THE MONA PASSAGE INTO THE CARIBBEAN. THE
RESULTING WEAK UPPER RIDGE BETWEEN THESE UPPER TROUGHS IS
PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE CLUSTERS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVERING A BROAD AREA
FROM WITHIN 120/150 NM OF LINE FROM 22N55W 26N63W TO 27N68W. THE
ONLY LIMITING FACTOR IS THE RELATIVE DRY STABLE UPPER AIR ACROSS
THE CENTRAL ATLC BETWEEN 30W-65W. AN UPPER HIGH IN THE E
TROPICAL ATLC NEAR 10N27W IS KEEPING ANY CONVECTION THAT MIGHT
BE ASSOCIATED WITH THE TROPICAL WAVE W OF THE WAVE AXIS. THE
ATLC IS DOMINATED BY A SURFACE RIDGE THAT COVERS THE ENTIRE
BASIN INTO THE E GULF OF MEXICO AND ANCHORED BY A SERIES OF
HIGHS N OF THE REGION.

$$
WALLACE




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