Tropical Weather Discussion
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000
AXNT20 KNHC 011759
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT AUG 01 2015

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...

GALE-FORCE WINDS ARE BEING FORECAST ALONG THE COAST OF
COLOMBIA...STARTING AROUND 02/0600 UTC...FROM 11N TO 13N BETWEEN
74W AND 76W. THE GALE-FORCE WINDS ARE FORECAST TO LAST FOR ABOUT
12 HOURS OR SO. PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2/
FZNT02 KNHC...AND THE OFFSHORE FORECAST...MIAOFFNT3/FZNT23
KNHC...FOR MORE DETAILS.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 22W/23W FROM 17N
SOUTHWARD...MOVING WESTWARD 10 TO 15 KNOTS. CONVECTIVE
PRECIPITATION...ISOLATED TO WIDELY SCATTERED MODERATE FROM 13N
TO 16N BETWEEN 21W AND 25W. SCATTERED STRONG PRECIPITATION IS
WITH NEARBY MONSOON TROUGH CONVECTIVE PRECIPITATION...FROM 10N
TO 12N BETWEEN 22W AND 31W.

AN ATLANTIC OCEAN 1012 MB LOW PRESSURE CENTER IS NEAR 13N37W.
THIS LOW CENTER HAS BEEN CLASSIFIED VIA THE DVORAK
CLASSIFICATION SYSTEM SINCE 29 JULY AT 1800 UTC. THE SYSTEM HAS
BECOME PROGRESSIVELY WEAKER WITH TIME...AND IT IS BECOMING TOO
WEAK TO CLASSIFY. THE FORECAST IS FOR IT TO OPEN INTO A SURFACE
TROUGH AT THE END OF THE NEXT 24 HOURS. CONVECTIVE
PRECIPITATION...SCATTERED STRONG FROM 12.5N TO 13N BETWEEN 38W
AND 39W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 55W/56W FROM 22N
SOUTHWARD...MOVING WESTWARD 20 KNOTS. VISIBLE SATELLITE IMAGERY
SHOWS CLOUDINESS THAT IS ASSOCIATED WITH THE WAVE TO BE COVERING
THE ATLANTIC OCEAN FROM 10N TO 22N BETWEEN 53W AND 59W.
CONVECTIVE PRECIPITATION...ISOLATED MODERATE FROM 18N TO 22N
BETWEEN 56W AND 58W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 82W/83W FROM 17N
SOUTHWARD...MOVING WESTWARD 15 KNOTS. AN AREA OF MIDDLE LEVEL TO
UPPER LEVEL CYCLONIC WIND FLOW COVERS THE CARIBBEAN SEA...
CENTRAL AMERICA...THE YUCATAN PENINSULA...AND THE ISTHMUS OF
TEHUANTEPEC OF SOUTHERN MEXICO FROM 12N TO 22N BETWEEN 85W AND
96W. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO ISOLATED
STRONG FROM 11N TO 17N BETWEEN 82W AND 85W.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL SECTIONS OF SENEGAL
NEAR 14N17W...TO 12N24W...TO THE 1012 MB LOW PRESSURE CENTER
THAT IS NEAR 13N37W...TO 11N38W AND 07N51W. CONVECTIVE
PRECIPITATION...SCATTERED STRONG FROM 10N TO 12N BETWEEN 22W AND
31W. WIDELY SCATTERED TO SCATTERED MODERATE AND ISOLATED STRONG
FROM 7N TO 11N BETWEEN 37W AND 52W.

...DISCUSSION...

...THE GULF OF MEXICO...

A STATIONARY FRONT PASSES THROUGH FLORIDA ALONG 84W/85W TO A
1010 MB LOW PRESSURE CENTER THAT IS JUST OFF THE FLORIDA COAST
NEAR 29.5N85W TO 28N90W 27N95W...AND INLAND ALONG THE TEXAS GULF
COAST NEAR 27N97W. THE 24-HOUR FORECAST IS FOR THE LOW CENTER TO
DISSIPATE. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO
STRONG IS FROM 27N TO 29.5N BETWEEN 85W AND 88W. SCATTERED
MODERATE TO ISOLATED STRONG IS FROM 26.5N TO 29.5N BETWEEN 82W
IN FLORIDA AND 85W IN THE GULF OF MEXICO. WARMING CLOUD TOP
TEMPERATURES AND WEAKENING/DISSIPATING CONVECTIVE PRECIPITATION
COVERS THE GULF OF MEXICO FROM 24N TO 28N BETWEEN 92W AND THE
COASTS OF THE DEEP SOUTH OF TEXAS AND NORTHEASTERN MEXICO.

MIDDLE LEVEL TO UPPER LEVEL NORTHWESTERLY WIND FLOW COVERS MUCH
OF THE GULF OF MEXICO. AN AREA OF MIDDLE LEVEL TO UPPER LEVEL
CYCLONIC WIND FLOW COVERS THE GULF OF MEXICO...THE CARIBBEAN
SEA...CENTRAL AMERICA...THE YUCATAN PENINSULA...AND THE ISTHMUS
OF TEHUANTEPEC OF SOUTHERN MEXICO FROM 12N TO 22N BETWEEN 85W
AND 96W.

A SURFACE RIDGE PASSES THROUGH 23N81W ALONG THE COAST OF
CUBA...THROUGH THE SOUTHERN SECTIONS OF THE GULF OF MEXICO...TO
THE COAST OF MEXICO ALONG 23N98W.

...THE CARIBBEAN SEA...

PLEASE READ THE SECTION ABOUT TROPICAL WAVES FOR MORE DETAILS
ABOUT THE AREA OF MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND FLOW
THAT COVERS THE WESTERN CARIBBEAN SEA FROM 12N TO 22N BETWEEN
85W AND 96W...AND THE NEARBY TROPICAL WAVE.

A MIDDLE LEVEL TO UPPER LEVEL CIRCULATION CENTER IS NEAR 16N63W.
COMPARATIVELY DRIER AIR IN SUBSIDENCE IN WATER VAPOR SATELLITE
IMAGERY SURROUNDS THIS FEATURE.

UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE SOUTHERN SECTIONS
OF THE CARIBBEAN SEA FROM 15N SOUTHWARD BETWEEN VENEZUELA ALONG
65W AND PANAMA ALONG 80W.

THE MONSOON TROUGH IS ALONG 9N/10N BETWEEN 77W AND BEYOND 84W IN
COSTA RICA. NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS
DIRECTLY ASSOCIATED WITH THE MONSOON TROUGH.

...HISPANIOLA...

CONVECTIVE PRECIPITATION...ISOLATED MODERATE TO LOCALLY STRONG
FROM 17N IN THE CARIBBEAN SEA TO 19N IN THE DOMINICAN REPUBLIC
BETWEEN 71W AND 74W. THIS PRECIPITATION IS AT THE SOUTHERN END
OF THE CYCLONIC WIND FLOW THAT IS MOVING AROUND THE 24N74W
MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER. MIDDLE
LEVEL TO UPPER LEVEL NORTHWESTERLY WIND FLOW IS MOVING ACROSS
HISPANIOLA.

CURRENT OBSERVATIONS...FEW LOW LEVEL CLOUDS ARE BEING OBSERVED
IN PORT-AU-PRINCE IN HAITI. IN THE DOMINICAN REPUBLIC...
SCATTERED LOW LEVEL CLOUDS AND A HIGH LEVEL CEILING COVER
BARAHONA. SCATTERED LOW LEVEL CLOUDS ARE IN SANTO DOMINGO. FEW
LOW LEVEL CLOUDS ARE IN LA ROMANA AND PUNTA CANA. FEW
CUMULONIMBUS CLOUDS...SCATTERED LOW LEVEL AND SCATTERED HIGH
LEVEL CLOUDS ARE IN SANTIAGO. FEW LOW LEVEL CLOUDS AND SCATTERED
HIGH LEVEL CLOUDS ARE BEING REPORTED IN PUERTO PLATA.

THE GFS MODEL FORECAST FOR 250 MB SHOWS THAT NORTHWESTERLY WIND
FLOW WILL CROSS HISPANIOLA FOR THE NEXT 24 HOURS...THANKS TO THE
CURRENT 24N74W MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION
CENTER. A CYCLONIC CIRCULATION CENTER THAT IS FORECAST TO BE
ABOUT 75 NM TO THE SOUTHEAST OF PUERTO RICO IN 24 HOURS IS
FORECAST TO MOVE NORTHWESTWARD IN THE DIRECTION OF HISPANIOLA.
HISPANIOLA WILL FIND ITSELF IN THE MIDDLE OF TWO SEPARATE
CYCLONIC CIRCULATION CENTERS FOR THE SECOND 24-HOUR TIME
INTERVAL. THE GFS MODEL FOR 500 MB SHOWS THAT AN ANTICYCLONIC
CIRCULATION CENTER IS FORECAST TO BE ABOUT 100 NM TO THE
SOUTHWEST OF HISPANIOLA AT THE START OF THE 48-HOUR FORECAST
CYCLE. A SECOND AND COMPARATIVELY MUCH LARGER-SCALE ANTICYCLONIC
CIRCULATION CENTER IS FORECAST TO BE NEAR BERMUDA. HISPANIOLA
WILL FIND ITSELF WITH NORTHEASTERLY WIND FLOW IN THE EASTERN
HALF OF THE AREA AND SOUTHWESTERLY WIND FLOW IN THE WESTERN HALF
OF THE AREA FOR AT LEAST THE FIRST 24 HOURS OR SO. NORTHEASTERLY
WIND FLOW WILL COVER HISPANIOLA FOR THE NEXT 12 HOURS OR SO AS
AN INVERTED TROUGH APPROACHES THE AREA FROM THE EAST. THE
INVERTED TROUGH DISSIPATES...AND SOUTHERLY WIND FLOW WILL
CONTINUE UNTIL THE END OF THE 48-HOUR FORECAST PERIOD. THE GFS
MODEL FOR 700 MB SHOWS THAT THE WIND FLOW WILL CHANGE FROM
SOUTHEASTERLY AT THE START OF THE 48-HOUR FORECAST PERIOD...TO
EASTERLY...TO NORTHEASTERLY/EASTERLY...FOR THE FIRST 24 HOURS.
AN INVERTED TROUGH WILL MOVE WESTWARD ACROSS THE AREA FOR THE
SECOND ROUND OF 24 HOURS.

THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 24N74W...ABOUT 60 NM TO THE EAST OF THE BAHAMAS. CYCLONIC
WIND FLOW THAT IS MOVING AROUND THIS CENTER COVERS THE AREA FROM
20N TO 28N BETWEEN 68W AND 82W. THE CYCLONIC WIND FLOW COVERS
THE ATLANTIC OCEAN...FLORIDA...CUBA...AND THE BAHAMAS.
CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG
FROM 20N AND CUBA TO 28N BETWEEN 70W AND 80W. SCATTERED MODERATE
TO ISOLATED STRONG ALSO IS FROM 30N TO 32N BETWEEN 78W AND 80W
IN THE COASTAL WATERS OF GEORGIA AND SOUTH CAROLINA.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N31W TO
29N46W. A SHEAR AXIS CONTINUES FROM 29N46W TO 25N55W. A TROUGH
CONTINUES AGAIN FROM 25N55W TO 19N63W TO 16N63W IN THE CARIBBEAN
SEA. RAINSHOWERS ARE POSSIBLE FROM 20N TO 30N BETWEEN 58W AND
66W.

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
IS NEAR 23N33W. COMPARATIVELY DRIER AIR IN SUBSIDENCE SURROUNDS
THIS CIRCULATION CENTER.

A 1013 MB HIGH PRESSURE CENTER IS NEAR 30N50W. SURFACE ANTI-
CYCLONIC WIND FLOW COVERS THE AREA FROM 24N NORTHWARD BETWEEN
26W AND 70W. A SURFACE RIDGE EXTENDS FROM 30N26W...TO THE HIGH
CENTER...TO 28N68W...ACROSS THE BAHAMAS TO THE COAST OF CUBA
NEAR 23N81W AND THE STRAITS OF FLORIDA.

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

$$
MT



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