[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 120547
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI JUL 12 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...
A SURFACE TROUGH...THE REMNANTS OF CHANTAL...IS ANALYZED FROM
CENTRAL CUBA NEAR 22N80W TO 26N79W. SUPPORTED ALOFT BY AN UPPER
LEVEL LOW CENTERED OVER THE FLORIDA STRAITS NEAR 23N80W...THE
ENTIRE SYNOPTIC SYSTEM IS GENERATING SCATTERED MODERATE
CONVECTION ACROSS THE SW NORTH ATLC S OF 27N W OF 72W...
INCLUDING PORTIONS OF INLAND CUBA. WHILE THE AREAL COVERAGE OF
CONVECTION REMAINS RELATIVELY LARGE DUE TO MAXIMUM UPPER LEVEL
DIFFLUENCE COVERING THE REGION...ORGANIZATION LACKS DUE TO AN
INCREASED AMOUNT OF UPPER LEVEL WIND SHEAR. THE SURFACE TROUGH
IS FORECAST TO DRIFT NORTHWARD OVER THE NEXT 36 TO 48 HOURS WITH
A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 10N33W TO 18N33W MOVING W AT 10-15
KT. THE WAVE REMAINS EMBEDDED WITHIN THE ITCZ AXIS AND COINCIDES
WITH A GLOBAL MODEL INDICATED 700 MB TROUGH AND ASSOCIATED
VORTICITY MAXIMUM IN THE VICINITY OF 15N34W. TOTAL PRECIPITABLE
WATER IMAGERY SHOWS A RELATIVE MOISTURE MAXIMUM FROM 10N-19N
BETWEEN 27W-36W. ISOLATED MODERATE CONVECTION IS FROM 06N-13N
BETWEEN 31W-37W.

TROPICAL WAVE EXTENDS FROM 12N80W TO 21N80W MOVING W AT 10-15
KT. THE WAVE...THE SOUTHERN EXTENT OF ENERGY ASSOCIATED WITH THE
REMNANTS OF CHANTAL...CONTINUES WESTWARD WHILE PARTIAL ENERGY
HAS FRACTURED TO THE NORTH AS A SURFACE TROUGH AND NO DEFINED
LOW-LEVEL CIRCULATION CENTER. PLENTY OF LOW-LEVEL MOISTURE
CONVERGENCE AND MID-LEVEL VORTICITY ARE AIDING IN GENERATING
WIDELY SCATTERED MODERATE CONVECTION FROM 16N-27N BETWEEN 73W-
83W...INCLUDING CUBA...THE BAHAMAS...JAMAICA...AND THE CAYMAN
ISLANDS. THE WAVE IS EXPECTED TO TRACK ACROSS THE WESTERN
CARIBBEAN SEA AND PORTIONS OF CENTRAL AMERICA OVER THE WEEKEND.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
10N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
10N38W TO 06N54W. SCATTERED MODERATE CONVECTION IS FROM 08N-10N
BETWEEN 17W-21W. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM
EITHER SIDE OF THE ITCZ AXIS BETWEEN 38W-51W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES EAST-NORTHEASTERLY UPPER LEVEL
FLOW NORTH OF A BROAD TROUGH AXIS EXTENDING FROM AN UPPER LEVEL
LOW CENTERED OVER THE FLORIDA STRAITS NEAR 23N80W TO OVER EAST-
CENTRAL MEXICO NEAR 22N100W. MOSTLY DRY AND STABLE AIR ALOFT IS
NOTED OVER THE NORTHERN GULF WATERS THIS EVENING WHILE A SURFACE
RIDGE ANCHORED BY A 1016 MB HIGH CENTERED NEAR 25N89W LIES
BENEATH PROVIDING FOR OVERALL TRANQUIL CONDITIONS FROM 22N-28N.
THE SURFACE RIDGING HAS WEAKENED INFLUENCE OVER THE NORTHERN
GULF COAST WITH ISOLATED SHOWERS AND TSTMS OCCURRING N OF 28N
THIS EVENING. ANOTHER WEAKNESS IN THE SURFACE RIDGE IS NOTED
ACROSS THE FLORIDA STRAITS AS THE SPECIAL FEATURE...REMNANTS OF
CHANTAL...BEGIN TO IMPACT THE SOUTHERN FLORIDA PENINSULA AND
ADJACENT COASTAL WATERS SURROUNDING THE FLORIDA KEYS THROUGH THE
OVERNIGHT HOURS. ACROSS PORTIONS OF THE SW GULF...WITHIN MOSTLY
WESTERLY FLOW ALOFT ON THE SOUTHERN PERIPHERY OF THE UPPER LEVEL
TROUGHING...MIDDLE TO UPPER LEVEL MOISTURE INCREASES WITH
ISOLATED SHOWERS OCCURRING S OF 23W. LOOKING AHEAD...SURFACE
RIDGING IS EXPECTED TO REMAIN IN PLACE ACROSS THE BASIN THROUGH
EARLY NEXT WEEK WITH GENERALLY E-SE WINDS PERSISTING.

CARIBBEAN SEA...
THE PRIMARY FOCUS FOR THE CARIBBEAN REMAINS ON THE SOUTHERN
EXTENT OF ENERGY...REMNANT ENERGY OF CHANTAL...MOVING WESTWARD
AS A TROPICAL WAVE ALONG 80W IN THE WESTERN CARIBBEAN. THE
TROPICAL WAVE CONTINUES GENERATING WIDELY SCATTERED SHOWERS AND
TSTMS FROM 15N-22N BETWEEN 76W-83W...INCLUDING MUCH OF CUBA...
JAMAICA...AND THE CAYMAN ISLANDS THIS EVENING. THE WAVE IS
EXPECTED TO DRIFT WESTWARD OVER THE WEEKEND BRINGING INCREASED
CHANCES OF PRECIPITATION TO THE NW CARIBBEAN AND PORTIONS OF
CENTRAL AMERICA. OTHERWISE...THE MONSOON TROUGH AXIS EXTENDS
ALONG 11N IN THE SW CARIBBEAN AND IS ONLY GENERATING A FEW
ISOLATED SHOWERS AND TSTMS S OF 13N W OF 80W. THE REMAINDER OF
THE CENTRAL AND EASTERN CARIBBEAN HAS RESUMED AN OVERALL QUIET
PATTERN WITH WATER VAPOR IMAGERY INDICATING DRY AIR AND
SUBSIDENCE ALOFT...ALONG WITH LIGHT NORTHEAST TO EAST TRADES.
THE TRADES ARE FORECAST TO INCREASE GRADUALLY BETWEEN 65W-80W BY
EARLY TUESDAY DUE TO AN INCREASE PRESSURE GRADIENT BETWEEN A
CENTRAL ATLC RIDGE AND LOWER PRESSURE ACROSS THE SW CARIBBEAN
AND NORTHERN SOUTH AMERICA.

HISPANIOLA...
CURRENTLY...MOST OF THE REMNANTS OF CHANTAL HAVE SHIFTING NW OF
THE ISLAND WITH ONLY A FEW ISOLATED SHOWERS OCCURRING OVER NW
PORTIONS OF THE ISLAND THIS EVENING. SURFACE RIDGING TO THE
NORTH AND EAST WILL CONTINUE TO BUILD WESTWARD OVER THE NEXT 24
TO 36 HOURS AS CONDITIONS ACROSS HISPANIOLA ARE EXPECTED TO
IMPROVE LATE FRIDAY INTO EARLY SATURDAY. THEREAFTER...TRADES
WILL RESUME ACROSS THE REGION WITH THE MORE TYPICAL AFTERNOON
SCATTERED SHOWERS AND TSTMS OCCURRING ACROSS THE ISLAND DURING
THE WEEKEND INTO EARLY NEXT WEEK.

ATLANTIC OCEAN...
AN UPPER LEVEL LOW IS CENTERED OVER THE FLORIDA STRAITS NEAR
24N80W THAT IS PROVIDING SUPPORT FOR THE CONVECTION ASSOCIATED
WITH THE SPECIAL FEATURES SURFACE TROUGH...THE REMNANTS OF
CHANTAL THIS EVENING ACROSS THE EASTERN FLORIDA STRAITS AND
BAHAMAS. SCATTERED SHOWERS AND TSTMS ARE OCCURRING S OF 27N W OF
72W. THIS FEATURE IS EXPECTED TO SLIP NORTHWARD OVER THE NEXT 24
TO 36 HOURS AROUND THE WESTERN PERIPHERY OF SURFACE RIDGING
ACROSS THE REMAINDER OF THE SW NORTH ATLC. THE RIDGE IS ANCHORED
BY A 1022 MB HIGH CENTERED NE OF BERMUDA NEAR 33N63W. FARTHER
EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 29N59W THAT REMAINS
AT THE SOUTHWESTERN EXTENT OF A STATIONARY FRONT ANALYZED FROM
32N43W TO 31N50W TO 28N56W. MOISTURE ASSOCIATED WITH THE UPPER
LEVEL LOW AND A WEAK SURFACE TROUGH ANALYZED FROM 22N55W TO
27N54W ARE GENERATING ISOLATED SHOWERS AND TSTMS FROM 25N-32N
BETWEEN 53W-63W. GLOBAL MODELS INDICATE THIS UPPER LEVEL FEATURE
WILL DRIFT WESTWARD ACROSS THE SW NORTH ATLC OVER THE COMING
DAYS. FINALLY...THE EASTERN ATLC IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 31N37W. A
SAHARAN AIR LAYERS CONTINUES TO BE THE OVERALL DOMINATE FEATURE
PROVIDING FAIRLY STABLE CONDITIONS N OF 18N E OF 50W.

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

$$
HUFFMAN


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