[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 290510
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON JUN 29 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0445 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 45W S OF 17N MOVING W 10-15 KT AND IS
AFFECTING PORTIONS OF THE TROPICAL ATLC. THIS WAVE COINCIDES
WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL
PRECIPITABLE WATER PRODUCT FROM CIMSS. SATELLITE IMAGERY
INDICATES THAT THE WAVE COINCIDES WITH AN INVERTED-V PATTERN IN
THE COVERAGE OF LOW LEVEL CLOUDS. SATELLITE-DERIVED WINDS ALSO
INDICATE CYCLONIC CURVATURE IN THE LOW LEVEL FLOW NEAR THIS
WAVE. STABLE ATMOSPHERIC CONDITIONS BENEATH AN UPPER LEVEL RIDGE
AND DEEP LAYER DRY AIR ARE INHIBITING DEEP CONVECTION NEAR THIS
WAVE. HOWEVER...SCATTERED SHOWERS ARE OCCURRING FROM 9N-12N
BETWEEN 40W-43W.

A TROPICAL WAVE IS ALONG 81W S OF 20N MOVING W NEAR 15 KT AND IS
AFFECTING PORTIONS OF THE W CARIBBEAN. THIS WAVE IS NOT
PARTICULARLY WELL-DEFINED. HOWEVER...THE CIMSS WAVETRAK PRODUCT
INDICATES THAT THE WAVE COINCIDES WITH WEAK LOW LEVEL CYCLONIC
CIRCULATION. SCATTERED MODERATE TO STRONG CONVECTION IS FROM
10N-14N BETWEEN 79W-83W. SCATTERED MODERATE CONVECTION IS FROM
15N-17N BETWEEN 82W-85W.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 9N13W 5N27W 5N38W 6N48W 5N55W.
SCATTERED MODERATE CONVECTION IS FROM 5N-12N BETWEEN 17W-25W.
SCATTERED MODERATE CONVECTION IS ALSO FROM 5N-7N BETWEEN
30W-34W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH OVER THE SE GULF EXTENDS FROM 26N86W TO THE
COAST OF THE YUCATAN PENINSULA NEAR 21N90W TO 17N91W. LOW LEVEL
CONVERGENCE IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS
WITHIN 90 NM EITHER SIDE OF THIS SURFACE TROUGH S OF 22N
INCLUDING PORTIONS OF THE YUCATAN PENINSULA AND GUATEMALA. THIS
ACTIVITY IS ALSO BEING SUPPORTED BY UPPER LEVEL DIVERGENCE
ASSOCIATED WITH AN UPPER LEVEL RIDGE OVER THE YUCATAN PENINSULA
AND W CARIBBEAN SEA. ADDITIONALLY...ATMOSPHERIC INSTABILITY
ASSOCIATED WITH AN UPPER LEVEL LOW CENTERED OVER N MEXICO NEAR
25N100W IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS FROM
19N-24N W OF 96W INCLUDING ADJACENT AREAS OF E MEXICO. ELSEWHERE
ACROSS THE N GULF...SUBSIDENCE IN CONFLUENT SOUTHEASTERLY FLOW
ALOFT IS OCCURRING BETWEEN THE AFOREMENTIONED UPPER LEVEL LOW
OVER N MEXICO AND AN UPPER LEVEL HIGH OVER E TEXAS. THE
SUBSIDENCE IS SUPPORTING A 1012 MB SURFACE HIGH NEAR 27N93W.
HOWEVER... ATMOSPHERIC INSTABILITY IS INTERACTING WITH UPPER
LEVEL MOISTURE STREAMING SOUTHWARD OVER THE E GULF TO SUPPORT
SCATTERED SHOWERS AND THUNDERSTORMS N OF 27N E OF 86W.

CARIBBEAN SEA...
A TROPICAL WAVE IS ASSOCIATED WITH CONVECTION ACROSS THE W
CARIBBEAN AND IS DISCUSSED IN THE TROPICAL WAVES SECTION ABOVE.
THIS CONVECTION IS BEING SUPPORTED BY UPPER LEVEL DIFFLUENCE
BETWEEN AN UPPER LEVEL RIDGE OVER THE YUCATAN PENINSULA AND W
CARIBBEAN SEA AND AN UPPER LEVEL TROUGH OVER THE CENTRAL
CARIBBEAN...AS WELL AS THE PRESENCE OF DEEP LAYER MOISTURE.
ALSO...UPPER LEVEL DIFFLUENCE IS SUPPORTING SCATTERED SHOWERS N
OF 18N BETWEEN 74W-78W. ACROSS THE E CARIBBEAN...SUBSIDENCE IN
CONFLUENT WESTERLY FLOW ALOFT AND DEEP LAYER DRY AIR...INCLUDING
LOW/MID-LEVEL DRY SAHARAN AIR...ARE RESULTING IN GENERALLY FAIR
WEATHER. ADDITIONALLY...E TO SE WINDS OF 20 TO 25 KT ARE
OCCURRING ACROSS PORTIONS OF THE CENTRAL AND E CARIBBEAN.

ATLANTIC OCEAN...
ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER LEVEL TROUGH
OVER THE SW NORTH ATLC IS SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS N OF 28N BETWEEN 60W-68W. ALSO...DIFFLUENCE IN
NORTHWESTERLY FLOW ALOFT IS INTERACTING WITH DEEP LAYER MOISTURE
W OF THE UPPER LEVEL TROUGH TO SUPPORT SCATTERED SHOWERS AND
THUNDERSTORMS N OF 28N BETWEEN 74W-79W. FARTHER TO THE E...
GENERALLY FAIR WEATHER IS PRESENT ACROSS MUCH OF THE CENTRAL AND
E ATLC...WHERE SUBSIDENCE IS OCCURRING NEAR A BROAD SURFACE
RIDGE. THIS SURFACE RIDGE IS ASSOCIATED WITH A 1020 MB SURFACE
HIGH NEAR 29N43W. HOWEVER...AN UPPER LEVEL TROUGH N OF 17N E OF
24W IS SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 24N33W TO
26N24W TO 31N16W AND A STATIONARY FRONT THAT EXTENDS FROM 31N16W
TO 32N13W TO NE OF THE DISCUSSION AREA. LOW LEVEL CONVERGENCE IS
SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THE
SURFACE TROUGH AND STATIONARY FRONT. ALSO...ATMOSPHERIC
INSTABILITY ASSOCIATED WITH AN UPPER LEVEL LOW NEAR 27N50W IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM
26N-31N BETWEEN 46W-52W. ACROSS THE TROPICAL ATLC...MOIST
EASTERLY FLOW ALOFT IS PRESENT...WITH UPPER LEVEL DIFFLUENCE
SUPPORTING CONVECTION ASSOCIATED WITH THE ITCZ AND THE TROPICAL
WAVE ALONG 45W S OF 17N.

$$
COHEN


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