[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281156
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE AUG 28 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1115 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM ISAAC AT 28/1200 UTC IS NEAR 27.8N
88.2W. THIS POSITION IS ABOUT 105 MILES TO THE SOUTH-SOUTHEAST
OF THE MOUTH OF THE MISSISSIPPI RIVER...AND ABOUT 185 MILES TO
THE SOUTH-SOUTHEAST OF BILOXI MISSISSIPPI. ISAAC IS MOVING
NORTHWESTWARD AT AROUND 5 KNOTS. THE MINIMUM CENTRAL PRESSURE IS
976 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 60 KT WITH GUSTS
TO 75 KT. PLEASE READ THE FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY...
MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. CONVECTIVE PRECIPITATION
...NUMEROUS STRONG IS FROM 25N TO 28N BETWEEN 87W AND 91W.
CONVECTIVE DEBRIS CLOUDS WITH POSSIBLE RAINSHOWERS ARE IN THE
WATERS FROM CUBA TO 32N BETWEEN 76W AND 80W...IN AN AREA OF
MIDDLE LEVEL TO UPPER LEVEL DIFFLUENT WIND FLOW. BROKEN TO
OVERCAST MULTILAYERED CLOUDS COVER THE AREA FROM 19N IN THE
YUCATAN PENINSULA OF MEXICO TO 33N BETWEEN SOUTH CAROLINA AND
ALABAMA...INTO MISSISSIPPI...AND THE SOUTHEASTERN HALF OF
LOUISIANA. ALL RESIDENTS FROM FLORIDA TO LOUISIANA SHOULD STAY
TUNED TO ALL BULLETINS THAT ARE ISSUED BY THE NATIONAL HURRICANE
CENTER AND THE LOCAL NATIONAL WEATHER SERVICE OFFICES FOR
UPDATES ABOUT T.S. ISAAC.

AN ATLANTIC OCEAN 1012 MB LOW PRESSURE CENTER IS NEAR 22N43W.
NUMEROUS STRONG CONVECTIVE PRECIPITATION IS FROM 22N TO 25N
BETWEEN 40W AND 43W. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND
POSSIBLE PRECIPITATION ARE WITHIN 120 TO 210 NM ON EITHER SIDE
OF 29N27W 28N35W 25N40W 20N46W. MIDDLE LEVEL NORTHEASTERLY WIND
FLOW IS WITHIN 360 NM TO THE WEST OF MASS OF CONVECTIVE
PRECIPITATION. UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE
ATLANTIC OCEAN TO THE NORTH OF 20N BETWEEN 20W AND 40W.
ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY CONDUCIVE FOR
DEVELOPMENT DURING THE NEXT COUPLE OF DAYS. THIS SYSTEM HAS
A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT
48 HOURS AS THE LOW MOVES WEST-NORTHWESTWARD TO NORTHWESTWARD AT
9 TO 13 KNOTS.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 23N23W...ACROSS THE
WESTERN CAPE VERDE ISLANDS NEAR 17N25W...TO A 1011 MB LOW
PRESSURE CENTER THAT IS NEAR 12N25W. SCATTERED STRONG
CONVECTIVE PRECIPITATION IS FROM 12N TO 15N BETWEEN 21W AND 29W.

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

THE MONSOON TROUGH IS INDISTINCT AS IT HAS BEEN DISRUPTED BY
THE LARGE-SCALE WIND FLOW THAT IS MOVING AROUND THE 23N23W
12N25W TROPICAL WAVE...AND THE WIND FLOW THAT IS MOVING
AROUND THE 1012 MB LOW PRESSURE CENTER THAT IS NEAR 22N43W.
THE MONSOON TROUGH EVENTUALLY IS ALONG 14N42W 10N50W.
CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO ISOLATED
STRONG FROM 6N TO 11N BETWEEN AFRICA AND 20W...ELSEWHERE
FROM 8N TO 13N BETWEEN 24W AND 35W...ISOLATED MODERATE WITHIN
A 30 NM RADIUS 2N37W AND WEAKENING WITHIN A 30 NM RADIUS OF
10N45.5W...SCATTERED MODERATE TO STRONG FROM 12N TO 14N
BETWEEN 55W AND 60W NEAR BARBADOS.

...DISCUSSION...

THE GULF OF MEXICO...

TROPICAL STORM ISAAC IS MOVING THROUGH THE EASTERN HALF OF THE
AREA. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR DETAILS
ABOUT THIS CYCLONE.

THE NORTHERN YUCATAN PENINSULA MIDDLE LEVEL TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER OF 24 HOURS AGO HAS BECOME CAUGHT
UP IN AN ELONGATED NORTHWEST-TO-SOUTHEAST ORIENTED TROUGH.
A CYCLONIC CIRCULATION CENTER WAS NEAR 24N94W ABOUT SIX HOURS
AGO. THAT SAME CYCLONIC CIRCULATION IS NOW NEARLY DISSIPATED
NEAR 24N96W. THE LARGE-SCALE DEEP LAYER WIND FLOW OF ISAAC
DOMINATES AND PRACTICALLY HAS OVERRUN THE ELONGATED TROUGH
COMPLETELY. NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION
ACCOMPANIES THE TROUGH.

THE SURFACE PRESSURE PATTERN IN THE EASTERN GULF OF MEXICO
IS MADE UP OF THE CLOSED ISOBARS THAT SURROUND ISAAC.
THESE ISOBARS COVER THE AREA TO THE EAST OF 95W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT4...FOR MORE DETAILS ABOUT
TROPICAL STORM ISAAC.

FROM THE ATLANTIC OCEAN...INTO THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS ALONG 25N72W...TO
A CYCLONIC CIRCULATION CENTER THAT IS NEAR 19N73W IN WESTERN
HAITI...ACROSS THE CARIBBEAN SEA...TO THE COLOMBIA COAST NEAR
10N76W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE
PRECIPITATION IS IN THE DOMINICAN REPUBLIC TO THE EAST OF 70W.
BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE RAINSHOWERS
COVER THE AREAS TO THE SOUTH OF 24N BETWEEN 66W AND 80W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION
HAS BEEN OCCURRING IN AN AREA OF UPPER LEVEL DIFFLUENT WIND FLOW
IN THE CARIBBEAN SEA BETWEEN 80W AND 85W...MOVING FROM CUBA INTO
EASTERN HONDURAS AND NORTHEASTERN AND EASTERN NICARAGUA...AND TO
THE COASTAL WATERS AND POSSIBLY THE COASTAL PLAINS OF COSTA RICA
AND PANAMA.

THE REST OF THE CARIBBEAN SEA...

THE MONSOON TROUGH IS ALONG 9N73W IN COLOMBIA...THROUGH 9N80W
IN PANAMA...BEYOND NORTHWESTERN COSTA RICA. IT IS POSSIBLE THAT
THE SCATTERED STRONG CONVECTIVE PRECIPITATION...THAT IS IN THE
EASTERN PACIFIC OCEAN TO THE NORTH OF 6N BETWEEN 81W AND 85W
TO THE SOUTH OF PANAMA AND COSTA RICA...IS RELATED TO THE
MONSOON TROUGH.

BROAD UPPER LEVEL CYCLONIC WIND FLOW COVERS THE NORTHWESTERN
CORNER OF THE AREA...RESPONDING TO THE INFLUENCE OF THE WIND
FLOW THAT IS MOVING AROUND TROPICAL STORM ISAAC.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR MORE DETAILS ABOUT THE
20 TO 25 KNOT WINDS AND 8 TO 11 FOOT SEA HEIGHTS DURING THE
48 HOUR FORECAST PERIOD FROM 12N TO 18N BETWEEN 65W AND 79W.

THE REST OF THE ATLANTIC OCEAN...

BROAD MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS
THE ATLANTIC OCEAN TO THE SOUTH OF 30N BETWEEN 20W AND 60W.
COMPARATIVELY DRIER AIR IN SUBSIDENCE COVERS THE AREA...EXCEPT
FOR THE CONVECTIVE PRECIPITATION THAT ACCOMPANIES THE 1012 MB
LOW PRESSURE CENTER THAT IS NEAR 22N43W...AND THAT WHICH IS
RELATED TO THE MONSOON TROUGH/THE ITCZ NEAR BARBADOS.

A SURFACE RIDGE EXTENDS FROM A 1022 MB HIGH PRESSURE CENTER THAT
IS NEAR 31N23W...TO A 1021 MB HIGH PRESSURE CENTER THAT IS NEAR
32N54W...TO 24N61W...INTO THE CARIBBEAN SEA TO JAMAICA.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...FOR DETAILS
ABOUT 20 TO 25 KNOT WINDS AND 8 FOOT SEA HEIGHTS TO THE SOUTH
OF 26N TO THE WEST OF 78W FOR THE NEXT SIX HOURS. A SECOND
FEATURE OF INTEREST IS A 1011 MB LOW PRESSURE CENTER THAT STARTS
NEAR 22N43W...IS A POSSIBLE TROPICAL CYCLONE NEAR 23N45W IN
24 HOURS...AND A POSSIBLE TROPICAL CYCLONE NEAR 24N49W
IN 48 HOURS.

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

$$
MT




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