[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED SEP 04 2013

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...

A CARIBBEAN SEA 1009 MB LOW PRESSURE CENTER IS NEAR
16N65W...ABOUT 140 NM TO THE SOUTH-SOUTHEAST OF PUERTO RICO.
CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 15N TO 19N
BETWEEN 65W AND 67W. THIS PRECIPITATION COVERS PARTS OF PUERTO
RICO AND THE VIRGIN ISLANDS AND THE WATERS THAT ARE TO THE SOUTH
OF THIS AREA. THE 24-HOUR RAINFALL TOTALS IN INCHES FOR THE
PERIOD ENDING AT 04/1200 UTC...ACCORDING TO THE PAN AMERICAN
TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN...ARE 1.04 IN
GUADELOUPE...0.28 IN SAN JUAN PUERTO RICO...AND 0.18 IN
TRINIDAD. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS...AND A HIGH CHANCE OF BECOMING
A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. LOCALLY HEAVY
RAINFALL AND GUSTY WINDS ARE EXPECTED TO SPREAD OVER PARTS OF
THE LEEWARD ISLANDS...THE VIRGIN ISLANDS...PUERTO RICO...AND
HISPANIOLA DURING THE NEXT DAY OR TWO. A RECONNAISSANCE PLANE IS
INVESTIGATING THIS SYSTEM CURRENTLY.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 25W/26W TO THE SOUTH OF
18N...MOVING WESTWARD 20 KNOTS. A 1012 MB LOW PRESSURE CENTER IS
ALONG THE WAVE NEAR 12N.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 24N46W 17N45W 11N44W...
MOVING WESTWARD 15 KNOTS. CONVECTIVE PRECIPITATION...RAINSHOWERS
ARE POSSIBLE FROM 23N TO 27N BETWEEN 40W AND 44W...AND FROM 11N
TO 17N BETWEEN 40W AND 50W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 22N60W 11N59W MOVING
WESTWARD 10 TO 15 KNOTS. CONVECTIVE PRECIPITATION...NUMEROUS
STRONG FROM 10N TO 11N BETWEEN 56W AND 57W...FROM 14N TO 20N
BETWEEN 56W AND 61W...AND FROM 21N TO 22N BETWEEN 56W AND 58W.
IT IS EASILY POSSIBLE THAT SOME OF THE ISLANDS OF THE EASTERN
CARIBBEAN SEA MAY EXPERIENCE SOME OF THIS PRECIPITATION DURING
THE NEXT 12 TO 24 HOURS IF THE PRECIPITATION PATTERN REMAINS
INTACT DURING THE WESTWARD MOTION OF THE TROPICAL WAVE.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 21N74W NEAR THE SOUTHERN
BAHAMAS...THROUGH THE WINDWARD PASSAGE...TO 16N75W AND 10N76W...
MOVING WESTWARD 15 KNOTS.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL SENEGAL NEAR 14N17W TO
12N23W 12N26W 9N30W AND 6N39W. THE ITCZ CONTINUES FROM 6N39W TO
5N47W. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO STRONG
FROM 16N TO 18N BETWEEN 20W AND 24W. SCATTERED STRONG FROM 15N
TO 16N BETWEEN 26W AND 27W. SCATTERED MODERATE TO ISOLATED
STRONG FROM 8N TO 14N BETWEEN 26W AND 30W.

...DISCUSSION...

THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N77W IN
THE ATLANTIC OCEAN...ACROSS NORTH FLORIDA...TO 28N84W IN THE
GULF OF MEXICO...TO 28N91W...TO A 26N92W CYCLONIC CIRCULATION
CENTER. A SECOND MIDDLE LEVEL TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER IS NEAR 24N101W IN MEXICO. THIS CYCLONIC
CENTER HAS MOVED SOUTHWESTWARD FROM THE UPPER TEXAS GULF COAST
TO ITS PRESENT POSITION SINCE 01/2315 UTC. CONVECTIVE
PRECIPITATION...SCATTERED TO NUMEROUS STRONG FROM 24N TO 26N
BETWEEN SOUTH FLORIDA AND 90W. WIDELY SCATTERED TO SCATTERED
MODERATE TO ISOLATED STRONG COVERS THE REST OF THE AREA THAT IS
TO THE WEST OF 90W. ISOLATED MODERATE COVERS THE REST OF THE
AREA THAT IS TO THE EAST OF 90W. A SURFACE TROUGH IS ALONG
26N91W TO A 1011 MB LOW PRESSURE CENTER THAT IS NEAR 19N91W IN
THE WESTERN YUCATAN PENINSULA OF MEXICO.

 THIS SYSTEM HAS A LOW CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS...AND A LOW CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS.

A SURFACE RIDGE EXTENDS FROM A 1026 MB HIGH PRESSURE CENTER THAT
IS NEAR 33N52W TO 31N66W...ACROSS FLORIDA FROM 29N TO 30N...INTO
SOUTHEASTERN LOUISIANA.

FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE TO THE NORTH OF 27N
TO THE WEST OF 88W...

VISIBILITIES OF ONE MILE OR LESS AND HAZE ARE BEING OBSERVED AT
THE ICAO STATION KEMK. FAIR SKIES/CLEAR SKIES AT OR LOWER THAN
12000 FEET ARE BEING REPORTED ELSEWHERE ACROSS THE AREA.

FROM THE EASTERN ATLANTIC OCEAN...ACROSS THE CENTRAL ATLANTIC
OCEAN...THROUGH THE WINDWARD PASSAGE...INTO THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH/SHEAR AXIS IN SOME
LOCATIONS...PASSES THROUGH 32N18W TO 28N21W AND 28N38W...TO A
24N44W CYCLONIC CIRCULATION CENTER...TO A SECOND CYCLONIC CENTER
THAT IS NEAR 26N61W...TO 23N68W...CURVING TO 23N75W...THROUGH
THE WINDWARD PASSAGE...TO A 17N78W CYCLONIC CIRCULATION CENTER
IN THE CARIBBEAN SEA...BEYOND THE COASTAL BORDERS OF
SOUTHEASTERN NICARAGUA AND NORTHEASTERN COSTA RICA. CONVECTIVE
PRECIPITATION IN THE ATLANTIC OCEAN...RAINSHOWERS ARE POSSIBLE
FROM 23N TO 27N BETWEEN 40W AND 44W...AND TO THE NORTH OF 22N
BETWEEN 54W AND 61W. CONVECTIVE PRECIPITATION IN THE CARIBBEAN
SEA...ISOLATED TO WIDELY SCATTERED MODERATE BETWEEN 70W AND THE
LINE THAT RUNS FROM THE WINDWARD PASSAGE AND SOUTHEASTERN
NICARAGUA/NORTHEASTERN COSTA RICA. THE 24-HOUR RAINFALL TOTAL IN
INCHES FOR THE PERIOD ENDING AT 04/1200 UTC...ACCORDING TO THE
PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...
MIATPTPAN...IS 0.42 IN MONTEGO BAY IN JAMAICA...AND 0.34 IN
CURACAO.

THE REST OF THE CARIBBEAN SEA...

MIDDLE LEVEL TO UPPER LEVEL RIDGE ANTICYCLONIC WIND FLOW COVERS
THE WESTERN/NORTHWESTERN CORNER OF THE AREA...BETWEEN THE
CYCLONIC WIND FLOW THAT IS MOVING AROUND THE 17N76W CYCLONIC
CIRCULATION CENTER AND ASSOCIATED TROUGH... AND THE WIND FLOW
THAT IS MOVING AROUND THE 24N101W MEXICO CYCLONIC CENTER. BROAD
SURFACE LOW PRESSURE COVERS THE SOUTHWESTERN CORNER OF THE GULF
OF MEXICO. CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS
STRONG IS ALONG THE EASTERN COASTAL PLAINS/IN THE COASTAL WATERS
OF THE YUCATAN PENINSULA FROM NORTHERN BELIZE NORTHWARD.

BROAD MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS
THE CARIBBEAN SEA THAT IS TO THE EAST OF THE WINDWARD PASSAGE-TO-
SOUTHWESTERN CARIBBEAN SEA TROUGH.

THE MONSOON TROUGH IS ALONG 9N73W IN COLOMBIA TO 9N80W IN
PANAMA...BEYOND 10N85W IN COSTA RICA. CONVECTIVE
PRECIPITATION...WIDELY SCATTERED MODERATE TO ISOLATED STRONG TO
THE SOUTH OF 11N TO THE WEST OF 76W IN THE SOUTHWESTERN CORNER
OF THE CARIBBEAN SEA.

PLEASE READ THE HIGHS SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR MORE DETAILS ABOUT THE 1009
MB LOW PRESSURE CENTER THAT STARTS NEAR 16.5N 65W. EXPECT WINDS
20 TO 25 KNOTS AND SEA HEIGHTS LOWER THAN 8 FEET WITHIN 90 NM IN
THE NORTHERN SEMICIRCLE OF THE LOW CENTER. EXPECT ALSO SCATTERED
STRONG THUNDERSTORMS WITHIN 120 NM IN THE EASTERN SEMICIRCLE OF
THE LOW CENTER.

HISPANIOLA...

THE NUMEROUS STRONG CONVECTIVE PRECIPITATION THAT ACCOMPANIES
THE 1009 MB LOW PRESSURE THAT IS NEAR 16N65W MAY REACH
HISPANIOLA...AS IT IS NOW...DURING THE NEXT 24 HOURS OR SO. THIS
AMOUNT AND INTENSITY MAY RESULT IN SIGNIFICANT AMOUNTS OF
RAINFALL...AND IT MAY LEAD TO FLOODING IN SOME AREAS.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 23N75W IN
THE BAHAMAS...ACROSS SOUTHEASTERN CUBA AND JAMAICA...TO A 17N78W
CYCLONIC CIRCULATION CENTER THAT IS IN THE CARIBBEAN SEA...
BEYOND THE COASTAL BORDERS OF SOUTHEASTERN NICARAGUA AND
NORTHEASTERN COSTA RICA. CONVECTIVE PRECIPITATION IN THE
CARIBBEAN SEA...ISOLATED TO WIDELY SCATTERED MODERATE BETWEEN
70W AND THE LINE THAT RUNS FROM THE WINDWARD PASSAGE AND
SOUTHEASTERN NICARAGUA/NORTHEASTERN COSTA RICA.

THE GFS FORECAST FOR 700 MB SHOWS THAT EASTERLY WIND FLOW...THAT
IS ON THE NORTHWESTERN SIDE OF AN INVERTED TROUGH...WILL COVER
THE AREA FOR THE FIRST HALF OF THE FIRST 24 HOURS OF THE
FORECAST PERIOD. AN INVERTED TROUGH WILL MOVE ACROSS THE AREA
AND REMAIN THERE UNTIL THE END OF 48-HOUR FORECAST PERIOD. THE
GFS FORECAST FOR 500 MB SHOWS THAT A RIDGE WILL COVER THE AREA
FOR THE FIRST 24 HOURS OF THE FORECAST...WHILE AN INVERTED
TROUGH APPROACHES HISPANIOLA FROM THE EAST. THE INVERTED TROUGH
WILL COVER THE AREA FOR THE REST OF THE 48 HOUR FORECAST PERIOD.
THE GFS FORECAST FOR 250 MB SHOWS THAT AN EAST-TO-WEST ORIENTED
RIDGE WILL COVER THE AREA FOR THE ENTIRE TIME.

THE REST OF THE ATLANTIC OCEAN...

AN UPPER LEVEL INVERTED TROUGH IS ALONG 40W FROM 10N TO 18N.
NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS APPARENT.

BROAD SURFACE ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN
TO THE NORTH OF 20N TO THE EAST OF 42W. A 1025 MB HIGH PRESSURE
CENTER IS NEAR 33N33W.

A SURFACE RIDGE EXTENDS FROM A 1026 MB HIGH PRESSURE CENTER THAT
IS NEAR 33N52W TO 31N66W...ACROSS FLORIDA FROM 29N TO 30N...INTO
SOUTHEASTERN LOUISIANA.

THROUGH 32N34W TO 30N49W TO 28N61W...TO ANDROS ISLAND IN THE
BAHAMAS...SOUTHWESTWARD BEYOND WESTERN CUBA.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT THE SURFACE TROUGH FROM 24N61W TO A CARIBBEAN SEA
1009 MB LOW PRESSURE CENTER THAT IS NEAR 16.5N 65W. EXPECT
NORTHEAST TO EAST WINDS 20 TO 25 KNOTS AND SEA HEIGHTS TO 9 FEET
FROM 18N TO 23N TO THE WEST OF THE TROUGH TO 65W. EXPECT EAST TO
SOUTHEAST WINDS 20 TO 25 KNOTS EXCEPT 25 TO 30 KNOTS FROM 18N TO
21N. SEA HEIGHTS WILL RANGE FROM 8 TO 11 FEET FROM 17N TO 24N TO
THE EAST OF THE TROUGH TO 55W. EXPECT ALSO EAST TO SOUTHEAST
WINDS 20 TO 25 KNOTS AND SEA HEIGHTS TO 8 FEET FROM 13N TO 17N
BETWEEN 52W AND 56W. EXPECT SCATTERED STRONG THUNDERSTORMS FROM
15N TO 19N BETWEEN 57W AND 60W. THE ATLANTIC OCEAN 12-HOUR
FORECAST INCLUDES WINDS 20 KNOTS OR LESS AND SEA HEIGHTS TO 8
FEET.

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

$$
MT


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