[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031203
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI JUL 03 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1000 UTC.

...TROPICAL WAVES...

A LARGE TROPICAL WAVE EXTENDS FROM 17N35W TO 4N36W MOVING W NEAR
20 KT. THIS WAVE COINCIDES WITH A HIGH AMPLITUDE DEEP LAYER
MOISTURE MAXIMUM OBSERVED ON TOTAL PRECIPITABLE WATER IMAGERY.
SATELLITE IMAGERY INDICATES BROAD LOW-LEVEL CYCLONIC FLOW IN THE
VICINITY OF THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS FROM
4N-7N BETWEEN 34W-38W.

A TROPICAL WAVE IS ALONG 55W S OF 16N MOVING W 15-20 KT. THIS
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED ON
TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION
IS W OF THE WAVE AXIS FROM 10N-13N BETWEEN 56W-60W. THIS
CONVECTION IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE AROUND AN
UPPER LEVEL LOW IN THE ERN CARIBBEAN.

A TROPICAL WAVE IS ALONG 76W S OF 16N MOVING W 15-20 KT.
POSITION IS BASED ON CONTINUITY. SCATTERED MODERATE/STRONG
CONVECTION IS W OF THE WAVE AXIS FROM 3N-11N BETWEEN 77W-81W.
HOWEVER...THIS ACTIVITY IS MOST LIKELY ASSOCIATED WITH UPPER
LEVEL DIFFLUENCE AND SURFACE CONVERGENCE DUE TO THE E PACIFIC
ITCZ.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N15W 10N24W 9N35W 5N46W AND TO
THE NE COAST OF S AMERICA NEAR 5N53W. SCATTERED MODERATE
CONVECTION IS JUST OFF THE COAST OF AFRICA FROM 9N-11N BETWEEN
15W-19W AND FROM 5N-8N BETWEEN 40W-43W.

...DISCUSSION...

GULF OF MEXICO...
ISOLATED SHOWERS/THUNDERSTORMS THAT WERE ACROSS THE N CENTRAL
AND ERN GULF OF MEXICO HAVE PRIMARILY DIED OUT BESIDES A SMALL
AREA IN THE CENTRAL GULF FROM 25N-27N BETWEEN 90W-92W. THE UPPER
LEVEL TROUGH EXTENDING DOWN THE ERN UNITED STATES HAS BEGUN TO
SHIFT EWD AS AN UPPER LEVEL RIDGE BUILDS OVER MEXICO AND TEXAS.
UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL RIDGE OVER MEXICO
AND AN UPPER LEVEL LOW OVER THE NWRN CARIBBEAN NEAR 19N84W IS
SUPPORTING A SCATTERED SHOWERS/THUNDERSTORMS
OVER THE YUCATAN PENINSULA AND THE BAY OF CAMPECHE S OF 23N
BETWEEN 90W-95W. THE REMAINDER OF THE NW GULF OF MEXICO IS UNDER
A WEAK RIDGE WITH GENERALLY FAIR WEATHER AND LIGHT WINDS. EXPECT
THE RIDGE TO PERSIST OVER THE NEXT FEW DAYS.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS OVER THE NW CARIBBEAN NEAR 19N84W.
ATMOSPHERIC INSTABILITY NEAR THE UPPER LOW IS SUPPORTING
SCATTERED SHOWERS/THUNDERSTORMS OVER CUBA FROM 20N-22N BETWEEN
77W-80W...AND OVER HAITI FROM 18N-19N BETWEEN 73W-75W. AN UPPER
LEVEL HIGH IS OVER THE SW CARIBBEAN NEAR 12N79W. UPPER LEVEL
DIFFLUENCE BETWEEN THE UPPER LEVEL HIGH AND THE UPPER LEVEL LOW
IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS OVER THE WRN
CARIBBEAN S OF 18N W OF 80W. SURFACE CONVERGENCE NEAR THE E
PACIFIC ITCZ ALONG WITH THE TROPICAL WAVE ALONG 76W ARE
SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS S OF 11N W OF 77W. AN
UPPER LEVEL RIDGE COVERS THE ERN CARIBBEAN BRINGING DEEP LAYER
DRY AIR AND SUBSIDENCE. DUE TO THIS...THE REMAINDER OF THE ERN
CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER. ELY TRADE
WINDS OF 20-30 KT COVER THE MAJORITY OF THE CARIBBEAN. EXPECT
ANOTHER TROPICAL WAVE E OF THE LESSER ANTILLES TO REACH THE FAR
ERN CARIBBEAN WITHIN THE NEXT 24 HRS.

ATLANTIC OCEAN...
AN UPPER LEVEL HIGH IS OVER THE WRN ATLC NEAR 29N60W SUPPORTING
A 1023 MB SURFACE HIGH NEAR 27N60W. A 1014 MB SURFACE LOW IS IN
THE CENTRAL ATLC AT THE EDGE OF THE DISCUSSION AREA NEAR 32N45W.
A SURFACE TROUGH EXTENDS FROM THE LOW TO 28N45W. SURFACE
CONVERGENCE NEAR THIS TROUGH AS WELL AS UPPER LEVEL DIFFLUENCE
TO THE E OF AN UPPER LEVEL SHORTWAVE TROUGH WITH AXIS ALONG 42W
ARE SUPPORTING SCATTERED SHOWERS N OF 27N BETWEEN 39W-43W. A
BROAD SURFACE RIDGE COVERS THE REMAINDER OF THE ATLC BRINGING
GENERALLY FAIR WEATHER. THE RIDGE IS ANCHORED BY THE
AFOREMENTIONED SURFACE HIGH NEAR 27N60W AND A 1025 MB HIGH NEAR
31N26W. A BROAD LOW/MID-LEVEL DRY SAHARAN AIR LAYER COVERS THE E
ATLC S OF 25N E OF 55W LIMITING DEEP CONVECTION IN THIS AREA.
OVER THE TROPICAL ATLC...AN UPPER LEVEL HIGH IS CENTERED NEAR
11N41W ENHANCING CONVECTION NEAR THE ITCZ.

$$
WALTON










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