[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT AUG 17 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...

THE CENTER OF TROPICAL STORM ERIN AT 17/1500 UTC IS NEAR 19.8N
35.7W...ALSO ABOUT 1310 KM/710 NM TO THE WEST-NORTHWEST OF THE
CAPE VERDE ISLANDS. ERIN IS MOVING NORTHWESTWARD 10 KNOTS. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 35 KNOTS WITH GUSTS TO 45 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 SURFACE TROUGH IS ALONG 29N89W 27N91W 23N92W
18N93W. A 1010 MB LOW PRESSURE CENTER IS ALONG THE TROUGH NEAR
21N. 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 WEST AND NORTHWEST OF THE LINE
THAT RUNS FROM THE COAST OF LOUISIANA NEAR 91W TO 26N94W AND TO
THE MEXICO COAST NEAR 25N98W. A STATIONARY FRONT EXTENDS FROM
A 1016 MB SOUTHWESTERN GEORGIA LOW PRESSURE CENTER...TO
A 1013 MB COASTAL MISSISSIPPI LOW PRESSURE CENTER THAT IS NEAR
30N89W. A COLD FRONT EXTENDS FROM THE 1013 MB LOW CENTER TO
MEXICO JUST TO THE SOUTH OF THE BORDER WITH DEEP SOUTH OF
TEXAS...CURVING NORTHWESTWARD BEYOND THE TEXAS BIG BEND.
CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS STRONG WITHIN
60 NM ON EITHER SIDE OF THE LINE FROM THE FLORIDA PANHANDLE
NEAR 31N86W TO 27N89W 22N92W...INTO THE SOUTHWESTERN CORNER
OF THE GULF OF MEXICO TO 18N94W ALONG THE MEXICO COAST.
SCATTERED MODERATE TO ISOLATED STRONG IS IN THE WESTERN
ATLANTIC OCEAN...ALONG THE U.S.A. EAST COAST...WITHIN 30 NM
ON EITHER SIDE OF 30N80W 34N77W. ISOLATED MODERATE IN THE
ATLANTIC OCEAN TO THE NORTH OF 25N TO THE WEST OF 76W. THE
LOW-LEVEL CIRCULATION HAS BECOME ELONGATED AND LESS DEFINED
DURING THE PAST FEW HOURS AND SURFACE PRESSURES REMAIN HIGH.
UPPER-LEVEL WINDS ARE EXPECTED TO REMAIN ONLY MARGINALLY
CONDUCIVE FOR DEVELOPMENT AS THIS SYSTEM BEGINS
TO MOVE NORTHWESTWARD TO WEST-NORTHWESTWARD DURING THE NEXT
COUPLE OF DAYS. DEVELOPMENT IS LESS LIKELY AFTER 48 HOURS DUE TO
INTERACTION WITH LAND. ANYONE WITH INTERESTS IN THE CENTRAL AND
WESTERN GULF OF MEXICO SHOULD MONITOR THE PROGRESS OF THE SYSTEM
THROUGH EARLY NEXT WEEK. THIS SYSTEM HAS A MEDIUM CHANCE OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS...AND A
MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT
FIVE DAYS. THE AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT MISSION
THAT WAS SCHEDULED FOR THIS AFTERNOON HAS BEEN CANCELLED.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 56W/57W TO THE SOUTH OF
22N MOVING WESTWARD 15 KNOTS. RAINSHOWERS ARE POSSIBLE FROM 10N
TO 20N BETWEEN 50W AND 60W.

AN ATLANTIC OCEAN-TO-CARIBBEAN SEA TROPICAL WAVE IS ALONG
70W/71W TO THE SOUTH OF 22N...MOVING WESTWARD 15 KNOTS. A MIDDLE
LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 24N72W IN THE
ATLANTIC OCEAN...TO EASTERN CUBA AND JAMAICA...TO THE
NORTHEASTERN CORNER OF NICARAGUA...AND SOUTHWARD. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 16N
TO 19N BETWEEN 75W AND 76W THAT INCLUDES SOUTHWESTERN HAITI...
SCATTERED STRONG FROM 20N TO 22N BETWEEN 68W AND 70W IN THE
ATLANTIC OCEAN...RAINSHOWERS ARE POSSIBLE ELSEWHERE FROM 20N TO
22N BETWEEN 68W AND 75W NEAR CUBA...FROM CUBA NORTHEASTWARD.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL GUINEA NEAR 10N14W TO
7N19W 10N34W 11N40W...TO A 1012 MB LOW PRESSURE CENTER THAT IS
NEAR 12N47W. THE ITCZ CONTINUES FROM 12N47W TO 10N54W AND 8N58W.
CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS STRONG IN
SIERRA LEONE AND GUINEA FROM 8N TO 10N BETWEEN 12W AND 14W
SCATTERED STRONG FROM 7N TO 9N BETWEEN 21W AND 23W...AND FROM 8N
TO 11N BETWEEN 52W AND 55W. SCATTERED MODERATE TO ISOLATED
STRONG FROM 5N TO 9N BETWEEN 16W AND 21W...AND FROM 6N TO 11N
BETWEEN 55W AND 61W. ISOLATED TO WIDELY SCATTERED MODERATE FROM
8N TO 13N BETWEEN 43W AND 52W.

...DISCUSSION...

THE REST OF THE GULF OF MEXICO...

SCATTERED TO BROKEN LOW CLOUDS ARE IN THE LOWER RIO GRANDE
VALLEY OF TEXAS. BROKEN MULTILAYERED CLOUDS COVER THE NEW
ORLEANS METROPOLITAN AREA INCLUDING IN SLIDELL...AND IN
SOUTHEASTERN LOUISIANA. LOW CLOUD CEILINGS AND RAIN COVER
COASTAL SECTIONS OF MISSISSIPPI AND ALABAMA...CONTINUING INTO
THE FLORIDA PANHANDLE TO THE WEST OF APALACHICOLA. BROKEN
MULTILAYERED CLOUDS ARE IN THE TAMPA METROPOLITAN AREA.

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

LOW CLOUD CEILINGS ARE BEING OBSERVED AND/OR HAVE BEEN OBSERVED
DURING THE LAST FEW HOURS AT THE FOLLOWING ICAO STATIONS...
KMZG...KVAF...KGBK...KEIR...KSPR...KMYT...KMDJ...AND KDLP.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT4...FOR MORE DETAILS ABOUT THE 1010
MB LOW PRESSURE CENTER THAT IS NEAR 21N93W. EXPECT WINDS 20
KNOTS OR LESS AND SEAS LOWER THAN 8 FEET.

THE CARIBBEAN SEA...

NUMEROUS STRONG CONVECTIVE PRECIPITATION HAS BEEN OCCURRING IN
THE ATLANTIC OCEAN FROM 18N TO 20N BETWEEN 60W AND 65W...JUST
OUTSIDE THE NORTHEASTERN CORNER OF THE CARIBBEAN SEA. THE CLOUD
TOP TEMPERATURES HAVE BEEN WARMING DURING THE LAST FEW HOURS. IT
IS POSSIBLE THAT PRECIPITATION REMAINS IN THIS AREA. MIDDLE
LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC
OCEAN AND THE CARIBBEAN SEA FROM FROM 11N TO 24N BETWEEN 54W AND
70W.

A SURFACE RIDGE PASSES THROUGH THE ATLANTIC OCEAN NEAR 28N74W...
CROSSING CUBA TO 21N80W IN THE NORTHWESTERN CORNER OF THE
CARIBBEAN SEA...TO THE BORDER OF NICARAGUA/COSTA RICA NEAR
11N85W.

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

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 TO 8 FEET FROM 11N
TO 14N BETWEEN 72W AND 75W. EXPECT ALSO NORTHEAST WINDS 20 TO 25
KNOTS AND SEA HEIGHTS LOWER THAN 8 FEET IN THE WINDWARD PASSAGE.

HISPANIOLA...

A 70W/71W TROPICAL WAVE IS MOVING THROUGH THE WESTERN HALF OF
THE DOMINICAN REPUBLIC. UPPER LEVEL MOISTURE COVERS HISPANIOLA.
UPPER LEVEL SOUTHERLY WIND FLOW CONTINUES TO PUSH MOISTURE
ACROSS THE ISLAND. HISPANIOLA FINDS ITSELF ON THE EASTERN SIDE
OF A MIDDLE LEVEL TO UPPER LEVEL TROUGH THAT PASSES THROUGH
24N72W IN THE ATLANTIC OCEAN...TO EASTERN CUBA AND JAMAICA...TO
THE NORTHEASTERN CORNER OF NICARAGUA...AND SOUTHWARD. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 16N
TO 19N BETWEEN 75W AND 76W THAT INCLUDES SOUTHWESTERN HAITI...
SCATTERED STRONG FROM 20N TO 22N BETWEEN 68W AND 70W...
RAINSHOWERS ARE POSSIBLE ELSEWHERE FROM 20N TO 22N BETWEEN 68W
AND 75W NEAR CUBA. ISOLATED MODERATE IN THE ATLANTIC OCEAN TO
THE NORTH OF 25N TO THE WEST OF 76W.

THE 700 MB AND THE 500 MB GFS FORECASTS SHOW THAT AN INVERTED
TROUGH WILL COVER HISPANIOLA FOR ABOUT THE FIRST ONE-THIRD OF
THE 48 HOUR FORECAST PERIOD. A RIDGE WILL COVER THE AREA FOR THE
SECOND ONE-THIRD OF THE TIME. A SECOND INVERTED TROUGH WILL BE
ON TOP OF THE AREA DURING THE THIRD ONE-THIRD OF THE TIME. THE
250 MB GFS FORECAST SHOWS THAT ANTICYCLONIC WIND FLOW WILL COVER
THE AREA 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 MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 23N49W. CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN FROM
18N TO 31N BETWEEN 40W AND 58W. CONVECTIVE PRECIPITATION...
SCATTERED MODERATE TO THE NORTH OF 27N BETWEEN 48W AND 56W.

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 27N65W. CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN FROM
24N TO 29N BETWEEN 63W AND 70W. CONVECTIVE PRECIPITATION...
ISOLATED TO WIDELY SCATTERED MODERATE FROM 26N TO 28N BETWEEN
66W AND 68W.

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 33N31W. CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN TO THE
NORTH OF 30N BETWEEN 23W AND 40W.

A SURFACE RIDGE EXTENDS FROM A 1027 MB HIGH PRESSURE CENTER THAT
IS NEAR 35N53W TO BERMUDA...TO 28N74W...CROSSING CUBA TO 21N80W
IN THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA...TO THE BORDER
OF NICARAGUA/COSTA RICA NEAR 11N85W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT TROPICAL STORM ERIN. EXPECT ALSO WINDS 20 KNOTS OR
LESS AND SEA HEIGHTS TO 8 FEET FROM 17N TO 22N BETWEEN 50W AND
65W.

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

$$
MT


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