[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 052338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU JUL 05 2012

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 22N36W TO 12N33W MOVING W NEAR 20 KT. THE
WAVE LIES ON THE WRN SIDE OF A SURGE OF DEEP LAYER MOISTURE. THE
WAVE ALSO LIES ON THE LEADING EDGE OF A LARGE AREA OF SAHARAN
DUST THAT EXTENDS EWD TO THE AFRICAN COAST. THE DRY DUST E OF
THE WAVE IS LIMITING CONVECTION NEAR THE WAVE. CURRENTLY NO DEEP
CONVECTION IS ASSOCIATED WITH THE AXIS.

ACTIVE TROPICAL WAVE IS MOVING INTO CENTRAL CARIBBEAN ALONG
22N70W TO 15N75W MOVING W NEAR 20 KT. TOTAL PRECIPITABLE WATER
IMAGERY INDICATES THAT THE WAVE LIES ON THE WRN SIDE OF A LARGE
SURGE OF DEEP LAYER MOISTURE COVERING THE ERN CARIBBEAN AND
AREAS TO THE N IN THE ATLC. SATELLITE IMAGERY ALSO SHOWS
LOW-LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 19N-25N BETWEEN
61W-68W. SIMILAR ACTIVITY IS FROM 17N-24N BETWEEN
68W-74W...INCLUDING MUCH OF HISPANIOLA...AND FROM 16N-19N
BETWEEN 74W-79W...INCLUDING JAMAICA.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
GUINEA-BISSAU AT 12N16W CONTINUING ACROSS ATLC WATERS TO 8N37W.
THE ITCZ BEGINS AT 8N37W TO 8N62W. SCATTERED MODERATE CONVECTION
IS OFF THE W COAST OF AFRICA FROM 7N-11N E OF 18W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING REMAINS ACROSS THE GULF OF MEXICO TODAY
CENTERED AROUND A 1017 MB HIGH S OF LOUISIANA NEAR 28N91W...AS
OF 2100 UTC. THE RIDGE IS SUPPORTED BY A BROAD UPPER LEVEL RIDGE
COVERING THE NRN GULF. WEAK UPPER TROUGHING IS OVER BOTH THE SE
GULF...AND SW GULF...WITH WEAK RIDGING OVER THE S CENTRAL GULF.
MOSTLY DRY AIR ALOFT IS EMBEDDED WITHIN THE UPPER LEVEL
PATTERN...WHICH IS HELPING MAINTAIN FAIR CONDITIONS ACROSS THE
MAJORITY OF THE BASIN. A FEW ISOLATED SHOWERS ARE ACROSS THE SE
GULF EMBEDDED WITHIN THE LIGHT ANTI-CYCLONIC SURFACE FLOW AROUND
THE RIDGE. ISOLATED SHOWERS/THUNDERSTORMS ALSO DOT MUCH OF THE
GULF COAST STATES LIKELY DUE TO DAYTIME HEATING AND INSTABILITY.
SIMILAR ACTIVITY IS ACROSS THE YUCATAN PENINSULA AND MEXICO.
EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
WHILE THE NW CARIBBEAN IS UNDER MOSTLY FAIR CONDITIONS DUE TO
DRY AIR ALOFT...THE SW CARIBBEAN IS COVERED IN MOIST CONDITIONS.
SHOWERS/THUNDERSTORMS COVER THE AREA S OF 15N BETWEEN
82W-86W...AND S OF 12N BETWEEN 77W-82W...INCLUDING MUCH OF
NICARAGUA...COSTA RICA...AND PANAMA. SOME OF THIS ACTIVITY IS
INFLUENCED BY THE MONSOON TROUGH EXTENDING THROUGH PANAMA TO NRN
COLOMBIA. THIS AREA ALSO LIES UNDERNEATH AN UPPER OF DIFFLUENCE
ALOFT AROUND THE BASE OF A BROAD UPPER LEVEL TROUGH COVERING THE
NW CARIBBEAN...CUBA...AND THE BAHAMAS. THE UPPER TROUGH IS ALSO
ENHANCING CONVECTION NEAR A TROPICAL WAVE IN THE CENTRAL
CARIBBEAN. SEE TROPICAL WAVE SECTION ABOVE. THE COMBINATION OF
THE WAVE AND THE UPPER TROUGH IS SUPPORTING
SHOWERS/THUNDERSTORMS ACROSS MUCH OF HISPANIOLA AND JAMAICA. DRY
AIR ALOFT IS BEGINNING TO MAKE ITS WAY ACROSS THE FAR ERN
CARIBBEAN BEHIND THE SURGE OF MOISTURE ASSOCIATED WITH THE WAVE
PROVIDING FAIR CONDITIONS ACROSS THE LESSER ANTILLES. EXPECT THE
WAVE TO CONTINUE TO PUSH WWD DRAWING MOISTURE INTO THE CENTRAL
AND WRN CARIBBEAN.

ATLANTIC OCEAN...
DRY AIR ALOFT OVER THE SW NORTH ATLC IS PROVIDING MOSTLY FAIR
CONDITIONS ACROSS THE CENTRAL AND WRN BAHAMAS. A TROPICAL WAVE
MOVING THROUGH THE CENTRAL CARIBBEAN IS DRAWING MOISTURE ACROSS
THE ERN BAHAMAS WITH SHOWERS/THUNDERSTORMS S OF 25N BETWEEN 73W.
SEE TROPICAL WAVE SECTION FOR MORE DETAILS. THE WAVE ALSO LIES
UNDERNEATH THE DIFFLUENT SIDE OF AN UPPER LEVEL TROUGH COVERING
THE NW CARIBBEAN AND THE BAHAMAS...WHICH IS HELPING ENHANCE THE
LARGE AREA OF ACTIVITY. A NARROW UPPER LEVEL TROUGH ALONG 56W
CONTINUES TO SUPPORT A WEAK SURFACE TROUGH ALONG 28N49W TO
25N50W. THE REMAINDER OF THE CENTRAL AND ERN ATLC IS DOMINATED
BY SURFACE RIDGING AROUND A 1033 MB AZORES HIGH. THE RIDGE IS
SUPPORTED BY AN UPPER LEVEL RIDGE OVER THE FAR NRN ATLC...AS
WELL AS AN UPPER LEVEL RIDGE ACROSS THE TROPICAL ATLC CENTERED
NEAR 20N38W. A BROAD UPPER LOW IS CENTERED BETWEEN THE TWO
RIDGES NEAR 43N39W...BUT IS NOT CAUSING ANY SIGNIFICANT WEATHER.
THE LAST VISIBLE SATELLITE IMAGES OF THE DAY INDICATE ANOTHER
LARGE AREA OF DUST EXTENDS E OF THE TROPICAL WAVE IN THE
TROPICAL ATLC. DUST IS ALSO PRESENT W OF THE WAVE TO THE ERN
CARIBBEAN.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON





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