[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171143
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON DEC 17 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.

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

THE MONSOON TROUGH PASSES THROUGH NORTHWESTERN COASTAL SENEGAL
NEAR 7N11W TO 6N14W. THE ITCZ CONTINUES FROM 6N14W TO 3N24W
2N34W...CROSSING THE EQUATOR ALONG 39W...TO 1S40W...JUST OFF
THE COAST OF NORTHEASTERN BRAZIL. CONVECTIVE PRECIPITATION...
SCATTERED TO NUMEROUS STRONG FROM 1N TO 6N BETWEEN 9W AND 39W...
AND FROM 7N TO 8N BETWEEN 42W AND 44W.

...DISCUSSION...

THE GULF OF MEXICO...

BROAD AND GENTLE MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC
WIND FLOW COVERS THE AREA.

A DEEP LAYER TROUGH IS DIGGING THROUGH TEXAS FROM THE NORTH
CENTRAL SECTIONS TO THE TEXAS BIG BEND. THE TROUGH SUPPORTS
A SURFACE TROUGH THAT PASSES THROUGH WEST CENTRAL LOUISIANA...
TO THE UPPER TEXAS GULF COAST...TO THE LOWER RIO GRANDE VALLEY.
BROKEN TO OVERCAST MULTILAYERED CLOUDS COVER THE GULF WATERS
TO THE NORTHWEST OF 30N90W 25N97W. SCATTERED HIGH LEVEL CLOUDS
COVER THE REST OF THE GULF OF MEXICO TO THE NORTH OF 22N.
THESE CLOUDS ARE ON TOP OF SURFACE SOUTHERLY WIND FLOW.

A SURFACE RIDGE ORIGINATES IN THE ATLANTIC OCEAN...FROM 32N60W
TO 28N64W...PASSING OVER ANDROS ISLAND IN THE BAHAMAS...THROUGH
THE GULF OF HONDURAS...TO COASTAL GUATEMALA/COASTAL EL SALVADOR.

THE CARIBBEAN SEA...

MIDDLE LEVEL TO UPPER LEVEL SOUTHWESTERLY WIND FLOW COVERS THE
SOUTHEASTERN CORNER OF THE AREA...TO THE SOUTHEAST OF THE LINE
THAT PASSES THROUGH 16N62W TO 12N70W.

MIDDLE LEVEL NORTHEASTERLY WIND FLOW COVERS THE AREA TO THE
SOUTH OF 20N...TO THE NORTHWEST OF THE 16N62W 12N70W LINE.
SOME OF THE NORTHEASTERLY WIND FLOW IS RESIDUAL FLOW THAT
IS RELATED TO THE ATLANTIC OCEAN MIDDLE LEVEL TO UPPER LEVEL
TROUGH. SOME OF THE NORTHEASTERLY WIND FLOW ALSO IS RELATED
MORE TO RESIDUAL WIND FLOW THAT IS TO THE SOUTH OF THE BROAD
AND GENTLE MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW
THAT COVERS THE GULF OF MEXICO.

A SURFACE TROUGH IS ALONG 79W/80W FROM 13N TO 19N...WITH THE
NORTHERN PART OF THE TROUGH JUST TO THE WEST OF JAMAICA. THE
TROUGH IS DRIFTING WESTWARD. BROKEN LOW LEVEL TO MIDDLE LEVEL
CLOUDS AND POSSIBLE PRECIPITATION ARE FROM 13N TO 20N BETWEEN
77W AND 82W.

THE MONSOON TROUGH IS ALONG 6N75W IN NORTHWESTERN COLOMBIA...
TO 6N82W 9N85W AND BEYOND 8N90W IN THE EASTERN PACIFIC OCEAN.
BROKEN TO OVERCAST LOW CLOUDS AND POSSIBLE PRECIPITATION ARE
TO THE SOUTH OF 13N TO THE WEST OF 80W. THE CLOUDS AND POSSIBLE
PRECIPITATION ARE REACHING AND/OR HAVE BEEN REACHING PARTS OF
SOUTHEASTERN NICARAGUA AND PANAMA FOR THE LAST 6 TO 8 HOURS.

THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N48W IN
THE CENTRAL ATLANTIC OCEAN...TO 25N52W TO 15N58W. THIS TROUGH
SUPPORTS A FIRST SURFACE TROUGH THAT IS ALONG 32N43W TO 27N53W
25N61W 22N62W 21N70W. BROKEN LOW CLOUDS AND POSSIBLE
PRECIPITATION ARE WITHIN 120 NM ON EITHER SIDE OF 26N70W 26N60W
25N50W...AND WITHIN 60 NM ON EITHER SIDE OF 25N50W BEYOND 32N44W.
A SECOND SURFACE TROUGH IS ALONG 32N38W TO 27N43W 23N48W...
TO 18N50W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE
PRECIPITATION ARE WITHIN 180 NM ON EITHER SIDE OF 32N36W 25N43W.

A SURFACE TROUGH IS ALONG 16N49W 12N54W TO 6N56W IN COASTAL
SURINAME. SCATTERED MODERATE CONVECTIVE PRECIPITATION IS WITHIN
60 NM ON EITHER SIDE OF 23N41W 18N46W. BROKEN TO OVERCAST
MULTILAYERED CLOUDS AND POSSIBLE PRECIPITATION ARE FROM 10N TO
18N BETWEEN 44W AND 60W. SCATTERED MODERATE TO STRONG CONVECTIVE
PRECIPITATION IS FROM COASTAL GUYANA TO 12N BETWEEN 56W AND 61W
NEAR TRINIDAD/TOBAGO AND VENEZUELA.

A SURFACE RIDGE ORIGINATES IN THE ATLANTIC OCEAN...FROM 32N60W
TO 28N64W...PASSING OVER ANDROS ISLAND IN BAHAMAS...THROUGH THE
GULF OF HONDURAS...TO COASTAL GUATEMALA/COASTAL EL SALVADOR.

AN UPPER LEVEL TROUGH PASSES THROUGH 20N7W IN EASTERN MAURITANIA
TO 15N17W IN COASTAL SENEGAL...TO 7N26W. NO SIGNIFICANT
CONVECTIVE PRECIPITATION BASED SOLELY ON SATELLITE IMAGERY.

A SURFACE RIDGE EXTENDS FROM A 1027 MB HIGH PRESSURE CENTER
THAT IS NEAR 32N18W JUST TO THE WEST-SOUTHWEST OF THE MADEIRA
ARCHIPELAGO...TO 30N20W 25N28W 20N36W AND 9N48W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT...20 TO 25 KNOT WINDS AND 11 FOOT SEA HEIGHTS
TO THE NORTH OF 25N TO THE EAST OF THE 31N38W 18N52W SURFACE
TROUGH...ELSEWHERE TO THE NORTH OF 15N TO THE EAST OF 40W
AND TO THE NORTH OF 20N BETWEEN 40W AND 50W EXPECT TO REACH
20 KNOTS OR LESS AND SEA HEIGHTS TO 10 FEET. THE FORECAST FOR
18 HOURS INTO THE FORECAST PERIOD SHOWS THAT A COLD FRONT WILL
BE TO THE EAST OF THE AREA AT THAT MOMENT...WITH 20 TO 25 KNOT
WINDS AND SEA HEIGHTS REACHING 8 FEET TO THE NORTH OF 28N
TO THE WEST OF 75W.

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

$$
MT





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