[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 160003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUL 15 2009

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 26W S OF 15N MOVING W NEAR 15 KT.
SATELLITE IMAGERY SHOWS SOME MID-LEVEL CYCLONIC FLOW IN THE
VICINITY OF THIS WAVE. THIS WAVE ALSO COINCIDES WITH A LOW
AMPLITUDE DEEP LAYER MOISTURE MAXIMUM OBSERVED ON TOTAL
PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION IS
FROM 6N-12N BETWEEN 24W-29W.

A TROPICAL WAVE IS ALONG 42W/43W S OF 16N MOVING W NEAR 15 KT.
THIS WAVE COINCIDES WITH A LOW AMPLITUDE DEEP LAYER MOISTURE
MAXIMUM OBSERVED ON TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP
CONVECTION IS CURRENTLY ASSOCIATED WITH THIS WAVE.

A HIGHLY-AMPLIFIED TROPICAL WAVE IS OVER THE SW NORTH ATLC AND E
CARIBBEAN EXTENDING FROM 24N69W TO 16N71W TO 8N70W MOVING W NEAR
20 KT. SATELLITE IMAGERY SHOWS A WELL-DEFINED AND HIGHLY
AMPLIFIED INVERTED-V PATTERN IN THE LOW-LEVEL CLOUDS NEAR THE
WAVE. THE WAVE ALSO COINCIDES WITH A HIGH AMPLITUDE MOISTURE
MAXIMUM IN TOTAL PRECIPITABLE WATER. THE WAVE IS AT THE LEADING
EDGE OF AN ABUNDANT DRY LOW/MID-LEVEL SAHARAN AIR LAYER. THE DRY
AIR...ALONG WITH STABLE ATMOSPHERIC CONDITIONS BENEATH AN UPPER
LEVEL HIGH OVER THE E CARIBBEAN...ARE LIMITING DEEP CONVECTION
NEAR THE WAVE. HOWEVER...SCATTERED SHOWERS ARE WITHIN 100 NM OF
THE WAVE AXIS FROM 18N-21N.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 11N26W 9N35W 11N43W 9N50W
9N61W. BESIDES THE CONVECTION MENTIONED IN THE TROPICAL WAVE
ABOVE...SCATTERED MODERATE CONVECTION IS ALONG THE COAST OF WEST
AFRICA FROM 8N-12N E OF 16W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH IS OVER THE NORTH CENTRAL GULF OF MEXICO ALONG
30N89W 27N92W 26N95W. WIDELY SCATTERED MODERATE CONVECTION IS
ALONG THE COAST OF LOUISIANA FROM 27N-32N BETWEEN 90W-94W. HIGH
PRESSURE RIDGING EXTENDS FROM THE ATLANTIC TO THE E GULF OF
MEXICO. PATCHES OF WIDELY SCATTERED MODERATE CONVECTION IS OVER
FLORIDA. SIMILAR CONVECTION IS OVER THE YUCATAN PENINSULA FROM
16N-21N BETWEEN 88W-91W. IN THE UPPER LEVELS...AN UPPER LEVEL
HIGH IS CENTERED OVER ALABAMA PRODUCING MOSTLY NE UPPER LEVEL
FLOW OVER THE GULF OF MEXICO. AREAS OF UPPER LEVEL MOISTURE ARE
NOTED OVER THE E GULF E OF 93W. STRONG SUBSIDENCE IS OVER THE W
GULF AND TEXAS. EXPECT MORE CONVECTION OVER THE N GULF N OF 25N
...AND OVER THE BAY OF CAMPECHE OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
FRESH TO STRONG TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH THE
STRONGEST FLOW NEAR THE COAST OF COLOMBIA WHERE GALE CONDITIONS
ARE FORECAST TO BEGIN TONIGHT. A TROPICAL WAVE IS ALSO
TRAVERSING THE CARIBBEAN. DRY AIR AND SAHARAN DUST IS E OF THE
TROPICAL WAVE SUPPRESSING THUNDERSTORMS AND SHOWERS. SEE ABOVE.
NE SURFACE AND UPPER LEVEL WINDS ARE PRODUCING SCATTERED
MODERATE CONVECTION OVER W CUBA W OF 80W. IN THE UPPER
LEVELS...AN UPPER LEVEL HIGH IS CENTERED OVER THE SW CARIBBEAN
NEAR 12N80W. THE SOUTHERN EXTENT OF AN UPPER LEVEL TROUGH IS
OVER THE LEEWARD ISLANDS. UPPER LEVEL MOISTURE IS OVER CENTRAL
AMERICA AND THE W CARIBBEAN W OF 80W. STRONG SUBSIDENCE IS OVER
THE REMAINDER OF THE CARIBBEAN. EXPECT...THE DRY AIR BEHIND THE
TROPICAL WAVE TO CONTINUE TO SUPPRESS CONVECTION OVER THE NEXT
24 HOURS. THE SW CARIBBEAN MAY HAVE SOME CONVECTION HOWEVER.

ATLANTIC OCEAN...
SCATTERED MODERATE CONVECTION IS OVER THE THE N BAHAMAS FROM
23N-26N BETWEEN 78W-79W. FURTHER E...A SURFACE TROUGH IS OVER
THE W ATLANTIC ALONG 27N67W 24N72W. SCATTERED SHOWERS ARE WITHIN
30 NM OH THE TROUGH. SURFACE RIDGING COVERS THE W ATLANTIC WITH
AXIS ALONG 28N W OF 55W. IN THE UPPER LEVELS...AN UPPER LEVEL
LOW IS CENTERED NEAR 30N50W PRODUCING SCATTERED MODERATE
CONVECTION FROM 28N-31N BETWEEN 60W-62W. AN UPPER LEVEL TROUGH
IS OVER THE E ATLANTIC N OF 20N AND E OF 35W. OVER THE TROPICS A
RIDGE AN UPPER LEVEL RIDGE EXTENDS FROM W AFRICA TO THE LEEWARD
ISLAND ALONG 15N.

$$
FORMOSA





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