[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 080002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE AUG 07 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.

...SPECIAL FEATURE...

HURRICANE ERNESTO IS CENTERED NEAR 18.7N 87.1W...AS OF 0000
UTC...OR ABOUT 55 NM E OF CHETUMAL MEXICO. ERNESTO IS MOVING
WNW AT 13 KT. MINIMUM CENTRAL PRESSURE IS 980 MB WITH MAXIMUM
SUSTAINED WINDS OF 75 KT WITH GUSTS TO 90 KT. PLEASE READ THE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC AND THE PUBLIC ADVISORY UNDER AWIPS/WMO
MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS. NUMEROUS STRONG
CONVECTION IS IMMEDIATELY W OF THE CENTER OF ERNESTO FROM
18N-20N BETWEEN 86W-87W. OUTER RAINBANDS WITH SCATTERED
MODERATE/ISOLATED STRONG CONVECTION SPAN FROM 15N-23N BETWEEN
81W-91W INCLUDING PORTIONS OF NRN CENTRAL AMERICA AND THE
YUCATAN PENINSULA. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ALSO EXTENDS SOUTHWARD INTO NICARAGUA AND COSTA RICA.

TROPICAL WAVE IS ALONG 18N30W TO A 1012 MB SURFACE LOW AT 12N31W
MOVING W AT 15-20 KT. LOW-LEVEL CYCLONIC FLOW IS AROUND THE LOW
CENTER AND SOUTHERN PORTION OF THE WAVE. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS MAINLY W OF THE AXIS FROM
10N-15N BETWEEN 31W-35W. WHILE THE LOW IS NOT WELL ORGANIZED AT
THIS TIME...UPPER LEVEL CONDITIONS COULD BECOME MORE CONDUCIVE
FOR FURTHER DEVELOPMENT OF THE SYSTEM OVER THE NEXT COUPLE OF
DAYS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 19N48W TO 13N49W MOVING W NEAR 20 KT. A
1011 MB SURFACE LOW IS ALONG THE WAVE AXIS AT 18N49W. THIS LOW
IS THE REMNANT LOW OF T.S. FLORENCE THAT WAS DOWNGRADED
YESTERDAY. THE WAVE/LOW COINCIDE WITH A LARGE SURGE OF DEEP
LAYER MOISTURE THAT IS BETWEEN 44W-56W...EVIDENT IN TOTAL
PRECIPITABLE WATER IMAGERY. A SMALL AREA OF SCATTERED MODERATE
CONVECTION IS FROM 17N-19N BETWEEN 50W-52W.

TROPICAL WAVE IS MOVING THROUGH THE EASTERN CARIBBEAN ALONG
17N64W TO 11N67W MOVING W AT 10 KT. THE WAVE COINCIDES WITH AN
AREA OF ENHANCED MOISTURE THAT COVERS THE EASTERN CARIBBEAN E OF
68W. THE WAVE ALSO LIES UNDERNEATH AN AREA OF DIFFLUENCE ALOFT
ON THE E SIDE OF AN UPPER TROUGH...WHICH IS ENHANCING
CONVECTION. CURRENTLY...SCATTERED MODERATE CONVECTION IS FROM
12N-18N BETWEEN 60W-66W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH IS ACROSS W AFRICA TO THE COAST OF MAURITANIA
AT 21N16W WHERE IT CONTINUES OVER WATER ALONG 15N23W 11N38W
PASSING THROUGH A SURFACE LOW ASSOCIATED WITH THE EASTERNMOST
TROPICAL WAVE. THERE IS CURRENTLY NO DEEP CONVECTION BESIDES
THAT ASSOCIATED WITH TROPICAL WAVES.

...DISCUSSION...

THE GULF OF MEXICO...

CYCLONIC FLOW COVERS THE SOUTHERN GULF OF MEXICO AROUND
HURRICANE ERNESTO IN THE NW CARIBBEAN. A FEW SHOWERS AND
THUNDERSTORMS ARE EMBEDDED IN THE FLOW FROM OUTER RAINBANDS. A
WEAK SURFACE TROUGH IS ACROSS THE NORTHERN GULF FROM 31N86W TO
29N80W...AS OF 2100 UTC. NO SHOWERS ARE NEAR THE
TROUGH...HOWEVER...SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS
PORTIONS OF THE FLORIDA PANHANDLE AND THE FLORIDA PENINSULA.
THIS IS LIKELY DUE TO DIFFLUENT FLOW ALOFT OVER THE NE GULF
BETWEEN AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS AND AN
UPPER LEVEL RIDGE OVER THE NW ATLC WATERS. A FEW
SHOWERS/THUNDERSTORMS ARE ALSO ALONG THE COAST OF LOUISIANA
ASSOCIATED WITH DIFFLUENCE FLOW ALOFT BETWEEN AN INVERTED UPPER
TROUGH OVER THE FAR WESTERN GULF AND AN UPPER LEVEL
RIDGE...OUTFLOW FROM ERNESTO...THAT COVERS THE MAJORITY OF THE
BASIN. EXPECT STRONGER WINDS ACROSS THE SOUTHERN GULF AS ERNESTO
TRACKS WESTWARD INTO THE YUCATAN PENINSULA AND EVENTUALLY THE
BAY OF CAMPECHE. SHOWERS/THUNDERSTORMS WILL BE VERY LIKELY
ACROSS THIS AREA. THE REMAINDER OF THE BASIN WILL BE UNDER WEAK
SURFACE RIDGING WITH SHOWERS/THUNDERSTORMS ACROSS THE NORTHERN
GULF COAST.

THE CARIBBEAN SEA...
HURRICANE ERNESTO IS IMPACTING THE NW CARIBBEAN TONIGHT BRINGING
STRONG WINDS AND HEAVY SHOWERS/THUNDERSTORMS TO MUCH OF CENTRAL
AMERICA AND THE YUCATAN PENINSULA. ERNESTO IS EXPECTED TO MAKE
LANDFALL IN THE YUCATAN PENINSULA WITHIN THE NEXT 6-12 HOURS.
SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. THE CENTRAL
CARIBBEAN IS MOSTLY CLEAR DUE TO DRY AIR ALOFT AROUND AN UPPER
LEVEL RIDGE OVER THE SW CARIBBEAN AND AN UPPER LEVEL LOW
CENTERED N OF HISPANIOLA. HOWEVER...DIFFLUENCE ALOFT AROUND THE
E SIDE OF THE UPPER LOW IS HELPING HELPING PRODUCE HEAVY
SHOWERS/THUNDERSTORMS OVER HISPANIOLA AND ACROSS THE EASTERN
CARIBBEAN NEAR A TROPICAL WAVE. SEE TROPICAL WAVE SECTION FOR
MORE DETAILS ON THE WAVE. EXPECT THE NW CARIBBEAN TO CONTINUE TO
SEE HEAVY WIND AND RAIN AS ERNESTO MOVES WESTWARD INTO THE
YUCATAN PENINSULA. MOISTURE ASSOCIATED WITH THE TROPICAL WAVE IN
THE EASTERN CARIBBEAN WILL BEGIN TO MOVE INTO THE CENTRAL
CARIBBEAN.

THE ATLANTIC OCEAN...
A WEAK PRESSURE GRADIENT IS ACROSS THE WESTERN ATLC WITH LIGHT
MOSTLY ANTI-CYCLONIC FLOW PRESENT. ALOFT...AN UPPER LEVEL RIDGE
COVERS THE AREA CENTERED NEAR 33N72W. A WEAK SURFACE TROUGH IS
ALONG 24N70W TO 21N70W COINCIDING WITH AN UPPER LEVEL LOW
CENTERED NEAR 22N70W. A FEW ISOLATED SHOWERS ARE NEAR THE
SURFACE TROUGH. A SECOND SURFACE TROUGH IS TO THE N ALONG 33N60W
TO 24N63W SUPPORTED BY AN UPPER LEVEL TROUGH ALONG 37N54W TO
26N64W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120
NM EITHER SIDE OF THE SURFACE TROUGH AXIS FROM 24N-28N. FARTHER
E...SURFACE RIDGING DOMINATES ANCHORED BY A 1024 MB HIGH
CENTERED NEAR 33N41W PROVIDING MOSTLY FAIR CONDITIONS. THE RIDGE
IS SUPPORTED BY A BROAD UPPER RIDGE COVERING MUCH OF THE
TROPICAL ATLC S OF 32N. VISIBLE SATELLITE IMAGERY INDICATES THAT
A BROAD AREA OF AFRICAN DUST EXTENDS ACROSS THE ATLC AROUND THE
TWO TROPICAL WAVES FURTHER SUPPORTING FAIR CONDITIONS.

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

$$
WALTON




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