TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON OCT 29 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 1045 UTC.

…SPECIAL FEATURES…

THE CENTER OF HURRICANE SANDY AT 29/1200 UTC IS NEAR 36.8N
71.1W. SANDY IS ABOUT 230 NM TO THE SOUTHEAST OF ATLANTIC CITY
NEW JERSEY…AND ABOUT 270 NM TO THE SOUTH-SOUTHEAST OF NEW YORK
CITY. SANDY IS MOVING NORTH-NORTHWEST 11 KT. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 946 MB. THE MAXIMUM SUSTAINED WIND
SPEEDS ARE 75 KNOTS WITH GUSTS TO 90 KNOTS. PLEASE READ THE
FORECAST/ADVISORY UNDER THE AWIPS/WMO HEADERS MIATCMAT3/WTNT23
KNHC…AND THE PUBLIC ADVISORY UNDER MIATCPAT3/WTNT33 KNHC FOR
MORE DETAILS. CONVECTIVE PRECIPITATION…SCATTERED MODERATE TO
STRONG FROM 35N TO 40N BETWEEN 67W AND 76W. THE SURFACE PRESSURE
PATTERN OF LOW PRESSURE COVERS THE ATLANTIC OCEAN FROM 26N TO
42N BETWEEN 57W AND 81W IN SOUTH CAROLINA…IN A CLOSED 1004 MB
ISOBAR.

…THE ITCZ/THE MONSOON TROUGH…

THE MONSOON TROUGH PASSES THROUGH THE COASTAL GUINEA-BISSAU
NEAR 12N16W 8N19W 8N24W. THE ITCZ CONTINUES FROM 8N24W TO 8N33W
7N40W TO 7N56W. CONVECTIVE PRECIPITATION…SCATTERED STRONG
WITHIN A 30 NM RADIUS OF 9N38.5W AND FROM 7N TO 9N BETWEEN 41W
AND 44W. ISOLATED MODERATE TO LOCALLY STRONG ELSEWHERE TO THE
SOUTH OF 10N TO THE EAST OF 56W. A SURFACE TROUGH IS ALONG
41W/42W TO THE SOUTH OF 13N…BREAKING UP THE ITCZ. ISOLATED
MODERATE CONVECTIVE PRECIPITATION IS FROM 10N TO 15N BETWEEN 40W
AND 50W.

…DISCUSSION…

THE GULF OF MEXICO…

BROAD MIDDLE LEVEL TO UPPER LEVEL NORTHWESTERLY-TO-WESTERLY WIND
FLOW COVERS THE AREA. THIS PATTERN IS TO THE WEST OF THE DEEP
LAYER TROUGH THAT SURROUNDS HURRICANE SANDY…IN THE WESTERN
ATLANTIC OCEAN. UPPER LEVEL MOISTURE HAS BEEN MOVING FROM MEXICO
INTO THE GULF OF MEXICO…MIXING WITH THE EARLIER COMPARATIVELY
DRIER AIR IN SUBSIDENCE THAT HAS BEEN SPANNING THE AREA FOR
AT LEAST THE LAST 48 HOURS OR SO.

THE DEEP LAYER TROUGH THAT ENGULFS HURRICANE SANDY AT THE MOMENT
SUPPORTS A SLOWLY-MOVING DISSIPATING COLD FRONT THAT PASSES
THROUGH THE ATLANTIC OCEAN NEAR 32N76W…ACROSS ABACO ISLAND AND
ANDROS ISLAND IN THE BAHAMAS…ACROSS CUBA NEAR 22N80W…TO THE
SOUTHEASTERN YUCATAN PENINSULA…TO THE ISTHMUS OF TEHUANTEPEC
OF MEXICO NEAR 17N92W. A DEFINITE BREAK EXISTS IN THE FRONTAL
BOUNDARY IN THE ISTHMUS OF TEHUANTEPEC. THE STATIONARY FRONT
STARTS NEAR 18N98W AND IT CURVES NORTHWESTWARD TO 24N100W.
WIDELY SCATTERED TO SCATTERED MODERATE CONVECTIVE PRECIPITATION
IS TO THE SOUTH OF 22N TO THE WEST OF 91W IN THE SOUTHWESTERN
CORNER OF THE AREA.

A SURFACE RIDGE PASSES THROUGH THE DEEP SOUTH OF TEXAS TO
20N96W IN COASTAL MEXICO…THROUGH NORTHERN GUATEMALA…
TO 16N81W IN THE WESTERN CARIBBEAN SEA.

PLEASE READ THE HIGH SEAS FORECAST…MIAHSFAT2…AND THE
OFFSHORE FORECAST…MIAOFFNT4…FOR DETAILS ABOUT THE
20 TO 30 KNOT WINDS AND 8 TO 10 FOOT SEA HEIGHTS TO THE
NORTH OF 23N TO THE EAST OF 90W.

THE CARIBBEAN SEA…

THE MIDDLE LEVEL TO UPPER LEVEL TROUGH THAT ENGULFS HURRICANE
SANDY PASSES THROUGH 32N72W IN THE ATLANTIC OCEAN…TO THE
CENTRAL BAHAMAS…ACROSS JAMAICA…TO 15N79W IN THE CARIBBEAN
SEA. COMPARATIVELY DRIER AIR IN SUBSIDENCE IS TO THE WEST
OF THE LINE THAT PASSES THROUGH 20N70W TO 16N76W TO 10N80W
AT THE PANAMA COAST.

BROAD MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW
COVERS THE REST OF THE CARIBBEAN SEA…TO THE EAST OF THE LINE
OF COMPARATIVELY DRIER AIR…20N70W 10N80W.

SCATTERED MODERATE TO STRONG CONVECTIVE PRECIPITATION IS WITHIN
60 TO 120 NM ON EITHER SIDE OF 14N70W 9N76W 4N81W. THE
PRECIPITATION IS OCCURRING IN THE AREA OF A MIDDLE LEVEL TO
UPPER LEVEL INVERTED TROUGH…THAT IS ALONG 13N73W 7N77W 3N79W.
THE TROUGH SPANS THE AREA FROM THE COASTAL WATERS OF
COLOMBIA…INTO COLOMBIA…TO THE EASTERN PACIFIC OCEAN TO THE
WEST OF COLOMBIA.

PLEASE READ THE HIGH SEAS FORECAST…MIAHSFAT2…AND THE
OFFSHORE FORECAST…MIAOFFNT3…FOR DETAILS ABOUT 20 TO 25 KNOT
WINDS AND 8 TO 9 FOOT SEA HEIGHTS TO THE NORTH OF 20N TO THE
WEST OF 84W…INCLUDING YUCATAN CHANNEL…FOR THE NEXT 24 HOURS
OR SO.

THE ATLANTIC OCEAN…

A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A 35N39W
CYCLONIC CIRCULATION CENTER TO 26N40W. NORTHWESTERLY-TO-WESTERLY
WIND FLOW COVERS THE ATLANTIC OCEAN TO THE NORTH OF 25N BETWEEN
AND 50W. THE TROUGH SUPPORTS A COLD FRONT THAT PASSES THROUGH
32N34W TO 25N39W. CONVECTIVE PRECIPITATION…SCATTERED MODERATE
TO STRONG TO THE NORTH OF 22N BETWEEN 25W AND 34W. BROKEN TO
OVERCAST MULTILAYERED CLOUDS ISOLATED MODERATE TO LOCALLY STRONG
CONVECTIVE PRECIPITATION ARE ELSEWHERE TO THE NORTH OF 17N
BETWEEN 20W AND 50W.

ISOLATED MODERATE TO LOCALLY STRONG CONVECTIVE PRECIPITATION
COVERS THE AREA FROM 19N TO 24N BETWEEN 53W AND 65W. THIS
PRECIPITATION IS OCCURRING ON THE EASTERN SIDE OF THE DEEP
LAYER TROUGH THAT SURROUNDS HURRICANE SANDY…AND UNDER THE
AREA OF A MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC CIRCULATION
CENTER THAT IS NEAR 20N54W.

A 1016 MB HIGH PRESSURE CENTER IS NEAR 22N24W. SURFACE
ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN FROM
11N TO 28N BETWEEN AFRICA AND 31W.

PLEASE READ THE HIGH SEAS FORECAST…MIAHSFAT2…FOR DETAILS
ABOUT HURRICANE SANDY. A SECOND AREA OF INTEREST HAS TO DO WITH
A 986 MB LOW PRESSURE CENTER THAT IS NEAR 35N40W AT THE START OF
THE FORECAST…MOVING TO 990 MB NEAR 35N35W AT 24 HOURS…AND
MOVING TO 993 MB NEAR 35N32W AT 48 HOURS. EXPECT 20 TO 30 KNOT
WINDS AND SEA HEIGHTS REACHING 15 FEET IN AREAS AROUND THE LOW
PRESSURE CENTER.