[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131106
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU AUG 13 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 28W/29W...FROM 18N
SOUTHWARD...MOVING WESTWARD 15 KNOTS. THE POSITION OF THE WAVE
AT 13/0600 UTC IS SLIGHTLY TO THE EAST OF THE POSITION FOR
13/0000 UTC...BASED ON SATELLITE IMAGERY...700 MB MODEL DATA...
AND TPW DATA. NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS
APPARENT IN SATELLITE IMAGERY.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 50W/51W FROM 15N
SOUTHWARD MOVING WESTWARD 10 KNOTS. THE POSITION OF THE WAVE AT
13/0600 UTC IS SLIGHTLY TO THE EAST OF THE POSITION FOR 13/0000
UTC...BASED ON SATELLITE IMAGERY...700 MB MODEL DATA...AND TPW
DATA. CONVECTIVE PRECIPITATION...ISOLATED MODERATE TO LOCALLY
STRONG WITHIN 60 NM ON EITHER SIDE OF 12N51W 10N54W 07N58W. FROM
10N TO 12N BETWEEN 50W AND 52W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 78W/79W FROM JUST TO THE
WEST OF THE WESTERN COAST OF JAMAICA TO PANAMA...MOVING WESTWARD
15 TO 20 KNOTS. THE WAVE COINCIDES WITH A 700 MB TROUGH. NO
SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS APPARENT IN
SATELLITE IMAGERY. THIS WAVE IS MOVING THROUGH AN AREA OF LARGE-
SCALE CYCLONIC WIND FLOW THAT SPANS THE CARIBBEAN SEA.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL BORDER SECTIONS OF
SENEGAL AND GAMBIA NEAR 13N16W...TO 11N24W AND 09N31W. THE ITCZ
CONTINUES FROM 09N31W TO 07N44W AND 06N50W. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE TO LOCALLY STRONG WITHIN 150
NM ON EITHER SIDE OF 12N16W 09N20W 07N25W 07N37W 08N45W 07N51W.

...DISCUSSION...

...THE GULF OF MEXICO...

LARGE-SCALE ANTICYCLONIC WIND FLOW IS SWEEPING ACROSS THE
NORTHERN HALF OF THE GULF OF MEXICO...FROM 24N NORTHWARD.

A COLD FRONT PASSES THROUGH 32N76W TO A 1013 MB SOUTHERN GEORGIA
LOW PRESSURE CENTER. A STATIONARY FRONT CONTINUES FROM THE
GEORGIA LOW PRESSURE CENTER...ALONG 30N...BEYOND SOUTHWESTERN
LOUISIANA. CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS
STRONG IS ALONG THE UPPER TEXAS GULF COAST. BROKEN TO OVERCAST
MULTILAYERED CLOUDS AND ISOLATED MODERATE CONVECTIVE
PRECIPITATION ELSEWHERE COVER THE AREA THAT IS FROM 25N TO 31N
BETWEEN FLORIDA AND TEXAS. WARMING CLOUD TOP TEMPERATURES AND
WEAKENING PRECIPITATION ARE IN THE SOUTHWESTERN CORNER OF THE
AREA FROM 22N SOUTHWARD.

A SURFACE RIDGE PASSES ACROSS ANDROS ISLAND...INTO THE SOUTH
CENTRAL GULF OF MEXICO...TO THE MEXICO GULF COAST NEAR 22N98W.

...THE CARIBBEAN SEA AND HISPANIOLA...

ONE MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 19N77W BETWEEN SOUTHEASTERN CUBA AND JAMAICA. A SECOND AND
COMPARATIVELY WEAKER MIDDLE LEVEL TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER IS TO THE SOUTH OF HAITI NEAR 17N72W. THESE
TWO INDIVIDUAL CYCLONIC CIRCULATION CENTERS ARE EMBEDDED IN THE
OVERALL LARGER-SCALE MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND
FLOW THAT SPANS THE CARIBBEAN SEA. A SURFACE TROUGH IS ALONG
70W/71W FROM 13N TO 17N. CONVECTIVE PRECIPITATION...SCATTERED
MODERATE TO ISOLATED STRONG ABOUT 60 NM TO THE SOUTH OF THE
SOUTHWESTERN PART OF THE COAST OF THE DOMINICAN REPUBLIC.
ISOLATED MODERATE FROM 14N TO PUERTO RICO AND HISPANIOLA FROM
65W WESTWARD...AND FROM 11N TO 14N BETWEEN 80W AND CENTRAL
AMERICA. RAINSHOWERS ARE POSSIBLE IN GENERAL ELSEWHERE TO THE
NORTHWEST AND NORTH OF THE LINE THAT RUNS FROM 18N65W TO 11N68W
TO 13N74W TO 09N80W.

SURFACE OBSERVATIONS FOR THE DOMINICAN REPUBLIC...SCATTERED LOW
LEVEL CLOUDS ARE BEING OBSERVED IN SANTO DOMINGO. FEW LOW LEVEL
CLOUDS ARE IN PUNTA CANA. A LOW LEVEL CLOUD CEILING IS BEING
REPORTED IN SANTIAGO.

THE GFS MODEL FORECAST FOR 250 MB SHOWS THAT THE CURRENT 17N72W
CYCLONIC CIRCULATION CENTER WILL MOVE NORTHWESTWARD TO 20N81W.
SOUTHERLY WIND FLOW WILL COVER HISPANIOLA FOR MOST OF THE FIRST
24 HOURS OF THE 48-HOUR FORECAST PERIOD THAT STARTS ON 13/0000
UTC. THE CYCLONIC CIRCULATION CENTER EVENTUALLY WILL MOVE TO
20N81W...AND THEN IT WILL DISSIPATE BY THE END OF THE 48-HOUR
FORECAST PERIOD. THE GFS MODEL FORECAST FOR 500 MB SHOWS THAT
INVERTED TROUGHS WILL MOVE ACROSS HISPANIOLA FOR THE FIRST 24
HOURS OF THE 48-HOUR FORECAST PERIOD. SOUTHEASTERLY WIND FLOW
EVENTUALLY COVERS THE ENTIRE AREA FOR DAY TWO. THE GFS MODEL
FORECAST FOR 700 MB SHOWS THAT INVERTED TROUGHS WILL MOVE
WESTWARD ACROSS HISPANIOLA FOR THE NEXT 48 HOURS. EXPECT
VARIATIONS IN THE WIND DIRECTION.

THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS IN THE COASTAL WATERS OF
THE SOUTH CAROLINA...GEORGIA...AND FLORIDA FROM 29N NORTHWARD.
COMPARATIVELY DRIER AIR IN SUBSIDENCE IS TO THE NORTH AND
NORTHWEST OF 29N81W BEYOND 32N78W. THE TROUGH SUPPORTS A COLD
FRONT THAT PASSES THROUGH 32N76W TO A 1013 MB SOUTHERN GEORGIA
LOW PRESSURE CENTER. A STATIONARY FRONT CONTINUES FROM THE
GEORGIA LOW PRESSURE CENTER...ALONG 30N...BEYOND SOUTHWESTERN
LOUISIANA. CONVECTIVE PRECIPITATION IN THE ATLANTIC OCEAN...
WIDELY SCATTERED TO SCATTERED MODERATE AND ISOLATED STRONG FROM
THE WATERS THAT ARE BETWEEN ANDROS ISLAND AND SOUTHEASTERN
FLORIDA...TO 28N78W...AND TO THE NORTHWEST OF 32N68W 29N72W
27N80W.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A 25N52W
CYCLONIC CIRCULATION CENTER...TO A 23N64W CYCLONIC CIRCULATION
CENTER. THE SURFACE TROUGH THAT WAS ALONG 31N31W 26N39W 29N47W
FOR THE 13/0000 UTC MAP ANALYSIS WEAKENED AND DISSIPATED.
CONVECTIVE PRECIPITATION...WIDELY SCATTERED MODERATE FROM 23N
NORTHWARD BETWEEN 47W AND 66W.

AN UPPER LEVEL TROUGH EXTENDS FROM A 31N24W CYCLONIC CIRCULATION
CENTER...TO 24N26W. COMPARATIVELY DRIER AIR IN SUBSIDENCE
SURROUNDS THE CYCLONIC CENTER AND TROUGH.

A SURFACE RIDGE PASSES THROUGH 32N58W TO 28N63W...TO ANDROS
ISLAND IN THE BAHAMAS...INTO THE SOUTH CENTRAL GULF OF
MEXICO...TO THE MEXICO GULF COAST NEAR 22N98W.

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

$$
MT
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