[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111049
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT JUL 11 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
1045 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 18N33W TO 10N36W TO 6N36W MOVING W
15-20 KT. THIS WAVE COINCIDES WITH A WELL-DEFINED MAXIMUM IN
DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER
PRODUCT FROM CIMSS. SATELLITE IMAGERY INDICATES THAT THIS WAVE
COINCIDES WITHIN A BROAD AREA OF LOW/MID-LEVEL CYCLONIC
TURNING...WITH SATELLITE-DERIVED WINDS INDICATING CYCLONIC
CURVATURE IN THE FLOW WITHIN THE 600-800 MB LAYER. DEEP
CONVECTION IS ABSENT NEAR THE WAVE SUPPRESSED BY LOW/MID-LEVEL
DRY SAHARAN AIR.

A TROPICAL WAVE EXTENDS FROM 20N67W TO 14N70W TO 9N70W MOVING W
20-25 KT. A LOW-LEVEL EASTERLY JET...DRIVEN BY THE STRONG HEIGHT
GRADIENT SW OF A RIDGE OVER THE CENTRAL NORTH ATLC...HAS FORCED
THE THIS WAVE TO ACCELERATE QUICKLY ENOUGH WESTWARD TO BECOME
DISCONNECTED FROM A LAGGING VORTICITY MAXIMUM FARTHER TO THE
NORTH. THIS IS GIVING THE WAVE...WHICH WAS PREVIOUSLY MORE
AMPLIFIED...A FRACTURED-LIKE APPEARANCE. THE NORTHERN VORTICITY
MAXIMUM IS BEING ANALYZED AS A SURFACE TROUGH EXTENDING FROM
24N62W TO 21N64W. ACROSS THE ABC ISLANDS...NE WINDS ARE NOTED
AHEAD OF THE WAVE...WITH SE WINDS BEHIND THE WAVE. SCATTERED
MODERATE CONVECTION IS FROM 16N-18N BETWEEN 67W-71W INCLUDING S
PORTIONS OF HISPANIOLA. THIS CONVECTION IS BEING ENHANCED BY A
MAXIMUM DEEP LAYER MOISTURE JUXTAPOSED WITH DIFFLUENT SOUTHERLY
FLOW ALOFT.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 9N25W 10N34W 6N46W 6N59W.
SCATTERED MODERATE CONVECTION IS FROM 6N-11N E OF 22W.

...DISCUSSION...

GULF OF MEXICO...
A LARGE UPPER HIGH OVER THE S CENTRAL PLAINS IS PROVIDING NLY
FLOW AND ADVECTING DRY AIR SOUTHWARD...HELPING TO SUSTAIN A
SURFACE RIDGE ALONG 28N. THE SOUTHERN END OF AN UPPER TROUGH
HAS BEEN PINCHED OFF...YIELDING AN UPPER LOW OVER W CUBA NEAR
22N85W. INSTABILITY NEAR AND E OF THE UPPER LOW IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS S OF 25N E OF 85W...AS
REVEALED BY DOPPLER RADAR AND LIGHTNING DATA. SCATTERED SHOWERS
AND TSTMS ARE ALSO OCCURRING OVER THE SW BAY OF CAMPECHE
ASSOCIATED WITH UPPER DIFFLUENCE AND LOW-LEVEL CONVERGENCE ALONG
THE COAST OF MEXICO. SFC RIDGING IS EXPECTED TO SHIFT NWD TODAY
AND SUN CAUSING LIGHT AND VARIABLE FLOW OVER THE N WATERS AND
MODERATE ELY WINDS OVER THE S WATERS.

CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE
SUBTROPICAL RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER
NORTHERN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST
OF COLOMBIA. AN EARLIER QUIKSCAT PASS CONFIRMED THE STRONG WINDS
NEAR THE COAST OF COLOMBIA AND ENHANCED NE FLOW IN THE WINDWARD
PASSAGE. THESE WINDS WILL REMAIN STRONG OVER THE NEXT SEVERAL
DAYS AS THE SUBTROPICAL RIDGE STRENGTHENS. ALOFT...AN UPPER
LEVEL TROUGH IS OVER THE W CARIBBEAN AND IS ASSOCIATED WITH AN
UPPER LEVEL LOW OVER W CUBA NEAR 22N85W. ATMOSPHERIC INSTABILITY
ASSOCIATED WITH THE UPPER LOW AND UPPER TROUGH IS RESULTING IN
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE NW
CARIBBEAN N OF 19N W OF 80W. UPPER LEVEL DIFFLUENCE S OF THE
TROUGH IS INTERACTING WITH DEEP LAYER MOISTURE OVER THE SW
CARIBBEAN TO RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS S OF
15N W OF 78W...INCLUDING ADJACENT AREAS OF CENTRAL AMERICA.

ATLANTIC OCEAN...
THE ATLANTIC DISCUSSION ZONE REMAINS RATHER QUIET WITH ONLY A
FEW AREAS OF UNSETTLED WEATHER TO MENTION. AN UPPER LEVEL TROUGH
OVER THE SW NORTH ATLC IS ASSOCIATED WITH A DISSIPATING COLD
FRONT EXTENDING FROM 28N75W TO 31N71W...WITH SCATTERED SHOWERS
AND THUNDERSTORMS FROM 23N-26N W OF 76W. FARTHER E...AN UPPER
LOW NEAR 29N57W AND A W-NW MOVING SFC TROUGH FROM 27N68W TO
21N75W ARE PRODUCING SCATTERED SHOWERS AND TSTMS WITHIN 120 NM
OF THE SFC TROUGH AXIS. THE REMAINDER OF THE BASIN IS RELATIVELY
INACTIVE SUPPRESSED BY DEEP LAYER RIDGING AND ASSOCIATED STABLE
AIR. THE SUBTROPICAL RIDGE IS EXPECTED TO STRENGTHEN SLIGHTLY
OVER THE NEXT FEW DAYS INCREASING TRADES OVER THE TROPICS.

$$
COHEN/CANGIALOSI


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