[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 16 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 FEATURES...

ERIN HAS WEAKENED TO A TROPICAL DEPRESSION. THE CENTER OF
TROPICAL DEPRESSION ERIN IS NEAR 16.9N 32.1W AT 16/1500 UTC.
THIS POSITION IS ABOUT 870 KM/470 NM TO THE WEST OF THE CAPE
VERDE ISLANDS. ERIN IS MOVING TOWARD THE WEST-NORTHWEST 15
KNOTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. THE
MAXIMUM SUSTAINED WIND SPEEDS ARE 30 KNOTS WITH GUSTS TO 40
KNOTS. PLEASE READ THE LATEST NHC PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT5/WTNT35 AND THE FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.
CONVECTIVE PRECIPITATION...WIDELY SCATTERED TO SCATTERED
MODERATE AND ISOLATED STRONG FROM 15N TO 18N BETWEEN 29W AND 34W.

A GULF OF MEXICO/YUCATAN PENINSULA TROPICAL WAVE IS ALONG 91W TO
THE SOUTH OF 25N. IT HAS BEEN MOVING AWAY FROM LAND SINCE THE
LATE NIGHT/EARLY MORNING HOURS OF TODAY. A 1009 MB LOW PRESSURE
CENTER IS ALONG THE TROPICAL WAVE NEAR 21.5N. A MIDDLE LEVEL TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 22N90W.
COMPARATIVELY DRIER AIR IN WATER VAPOR IMAGERY COVERS THE GULF
OF MEXICO TO THE SOUTH OF 25N TO THE WEST OF 90W. CONVECTIVE
PRECIPITATION...SCATTERED STRONG FROM 18N TO 21N BETWEEN 86W AND
87W...AND FROM 21N TO 25N BETWEEN 87W AND 90W. THIS
PRECIPITATION IS ON THE EASTERN SIDE OF THE WAVE. IT IS POSSIBLE
THAT ENVIRONMENTAL CONDITIONS MAY BECOME MORE FAVORABLE FOR
DEVELOPMENT INTO A TROPICAL CYCLONE IF THE LOW MOVES TOWARD THE
WEST OR WEST-NORTHWEST DURING THE NEXT COUPLE OF DAYS. ANYBODY
WITH INTERESTS IN THE CENTRAL AND WESTERN GULF OF MEXICO SHOULD
MONITOR THE PROGRESS OF THE SYSTEM THROUGH THE WEEKEND. THE LOW
CENTER WOULD MOVE INTO A LESS CONDUCIVE ENVIRONMENT FOR
DEVELOPMENT IF IT WERE TO MOVE MORE NORTHWARD TRACK. 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.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 49W/50W TO THE SOUTH OF
22N MOVING WESTWARD 15 KNOTS. NO SIGNIFICANT DEEP CONVECTIVE
PRECIPITATION ACCOMPANIES THE WAVE.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 63W TO THE SOUTH OF 22N
MOVING WESTWARD 15 TO 20 KNOTS. CONVECTIVE PRECIPITATION...
ISOLATED MODERATE FROM 16N TO 22N BETWEEN 64W AND 69W. SCATTERED
STRONG IN THE ATLANTIC OCEAN FROM 18N TO 19N BETWEEN 58W AND
59W. RAINSHOWERS ARE POSSIBLE ELSEWHERE IN THE CARIBBEAN SEA TO
THE NORTH OF 14N BETWEEN 60W AND 70W.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL GUINEA-BISSAU NEAR
12N16W TO 11N19W AND 11N22W. THE MONSOON TROUGH IS BROKEN UP BY
THE CIRCULATION THAT ACCOMPANIES T.D. ERIN. THE MONSOON TROUGH
CONTINUES FROM 12N34W TO 10N38W AND 11N48W. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 6N TO
13N BETWEEN AFRICA AND 20W...AND FROM 5N TO 12N BETWEEN 35W AND
57W.

...DISCUSSION...

THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS DIGGING SOUTHWARD...
THROUGH THE CENTRAL U.S.A. IT REACHES SOUTH CENTRAL TEXAS. A
STATIONARY FRONT EXTENDS FROM THE SOUTHEASTERN CORNER OF
GEORGIA...THROUGH THE FLORIDA PANHANDLE...THROUGH SOUTHEASTERN
LOUISIANA...TO A 1014 MB LOW PRESSURE CENTER THAT IS ALONG THE
BORDER OF EAST TEXAS/SOUTHWESTERN LOUISIANA. A COLD FRONT
CONTINUES FROM THE LOW CENTER TO THE MIDDLE TEXAS GULF COAST...
AND WESTWARD INTO WEST TEXAS. CONVECTIVE PRECIPITATION...WIDELY
SCATTERED TO SCATTERED MODERATE TO ISOLATED STRONG IN THE GULF
WATERS TO THE NORTH OF 27N TO THE EAST OF 91W. RAINSHOWERS ARE
POSSIBLE ELSEWHERE IN THE WATERS THAT ARE TO THE NORTH OF 25N TO
THE WEST OF 91W.

A SURFACE RIDGE PASSES THROUGH THE ATLANTIC OCEAN NEAR 27N72W...
ACROSS THE BAHAMAS INCLUDING ANDROS ISLAND...INTO THE
SOUTHEASTERN GULF OF MEXICO NEAR 25N84W.

BROKEN TO OVERCAST MULTILAYERED CLOUDS COVER THE REST OF THE
GULF OF MEXICO TO THE EAST OF 90W. SCATTERED TO BROKEN LOW LEVEL
TO MIDDLE LEVEL CLOUDS COVER THE REST OF THE GULF OF MEXICO TO
THE NORTH OF 25N TO THE WEST OF 90W...AND THE REST OF THE AREA
THAT IS TO THE SOUTH OF 25N BETWEEN 90W AND 93W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT4...FOR MORE DETAILS ABOUT THE 1009
MB LOW PRESSURE CENTER THAT IS NEAR 21N91W. EXPECT 20 TO 25 KNOT
WINDS AND SEA HEIGHTS LOWER THAN 8 FEET WITHIN 60 NM OF THE
CENTER.

THE CARIBBEAN SEA...

A 63W TROPICAL WAVE IS JUST TO THE EAST OF HISPANIOLA. EXPECT
RAINSHOWERS WITH THE WAVE. A MIDDLE LEVEL TO UPPER LEVEL TROUGH
EXTENDS FROM THE ATLANTIC OCEAN NEAR 31N63W TO 25N67W...CROSSING
HISPANIOLA...ENTERING THE CARIBBEAN SEA...REACHING 16N75W...TO
11N80W IN THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA. ISOLATED
MODERATE RAINSHOWERS ARE TO THE NORTH OF PUERTO RICO FROM 19N TO
22N BETWEEN 64W AND 67W.

THE MONSOON TROUGH IS ALONG 9N/10N BETWEEN 74W IN COLOMBIA...
ALONG THE NORTHERN COAST OF PANAMA...BEYOND 86W IN COSTA
RICA...INTO THE EASTERN PACIFIC OCEAN. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG TO THE SOUTH OF 12N TO THE WEST
OF 74W IN THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA.
SCATTERED STRONG FROM 4N TO 9N TO THE EAST OF 91W IN THE EASTERN
PACIFIC OCEAN.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR MORE DETAILS ABOUT NORTHEAST
TO EAST WINDS 20 TO 25 KNOTS AND SEA HEIGHTS FROM 8 TO 11 FEET
FROM 11N TO 18N BETWEEN 72W AND 82W.

HISPANIOLA...

A 63W TROPICAL WAVE IS JUST TO THE EAST OF HISPANIOLA. EXPECT
RAINSHOWERS WITH THE WAVE. A MIDDLE LEVEL TO UPPER LEVEL TROUGH
EXTENDS FROM THE ATLANTIC OCEAN NEAR 31N63W TO 25N67W...CROSSING
HISPANIOLA...ENTERING THE CARIBBEAN SEA...REACHING 16N75W...TO
11N80W IN THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA. ISOLATED
MODERATE RAINSHOWERS ARE TO THE NORTH OF PUERTO RICO FROM 19N TO
22N BETWEEN 64W AND 67W.

THE 700 MB GFS FORECAST SHOWS THAT HISPANIOLA WILL BE IN BROAD
CYCLONIC WIND FLOW AS A WESTWARD-MOVING INVERTED TROUGH CROSSES
THE AREA. A RIDGE FOLLOWS THE TROUGH FOR THE LAST 12 TO 18
HOURS. THE 500 MB GFS FORECAST SHOWS THAT A RIDGE WILL COVER
HISPANIOLA FOR ABOUT THE FIRST ONE-THIRD OF THE 48 HOUR FORECAST
PERIOD. AN INVERTED TROUGH WILL BE ON TOP OF THE AREA DURING THE
SECOND ONE-THIRD OF THE TIME. A RIDGE WILL COVER THE AREA FOR
THE LAST ONE-THIRD OF THE 48 HOUR PERIOD. THE GFS FORECAST FOR
250 MB STARTS WITH A INVERTED TROUGH ACROSS THE AREA FOR ABOUT
THE FIRST 12 HOURS OR SO. ANTICYCLONIC WIND FLOW COVERS THE AREA
FOR THE REST OF THE 48 HOURS...WITH AN EAST-TO-WEST ORIENTED
RIDGE.

THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A 33N28W
CYCLONIC CIRCULATION CENTER...TO 29N30W. A SHEAR AXIS CONTINUES
FROM 29N30W TO 28N40W. A TROUGH CONTINUES FROM 28N40W TO A
SECOND MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
THAT IS NEAR 24N48W...TO 20N48W. CONVECTIVE PRECIPITATION...
SCATTERED MODERATE WITHIN A 30 NM RADIUS OF 30N44W. RAINSHOWERS
ARE POSSIBLE ELSEWHERE WITHIN 150 NM TO 210 NM ON EITHER SIDE OF
THE LINE THAT PASSES THROUGH 32N26W 31N35W 27N40W 26N51W...AND
FROM 20N TO 26N BETWEEN 40W AND 50W.

A SURFACE RIDGE EXTENDS FROM A 1027 MB HIGH PRESSURE CENTER THAT
IS NEAR 35N48W TO 30N60W TO 27N72W...ACROSS THE BAHAMAS
INCLUDING ANDROS ISLAND...INTO THE SOUTHEASTERN GULF OF MEXICO
NEAR 25N84W. BROAD SURFACE ANTICYCLONIC WIND FLOW COVERS THE
ATLANTIC OCEAN TO THE NORTH OF 25W BETWEEN 30W AND 80W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT TROPICAL DEPRESSION ERIN.

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

$$
MT


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