Tropical Weather Discussion
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000
AXNT20 KNHC 042343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE AUG 04 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2330 UTC.

...SPECIAL FEATURES...

A STRONG PRESSURE GRADIENT WILL DEVELOP ONCE AGAIN THIS EVENING
BETWEEN THE SURFACE RIDGING ANCHORED ACROSS THE SW ATLANTIC AND
LOWER PRESSURES ANALYZED ACROSS NORTHERN COLOMBIA AND EASTERN
PANAMA. WITH THESE...GALE FORCE WINDS ARE EXPECTED TO DEVELOP BY
05/00 UTC FROM 11N-14N BETWEEN 72W-76W. SEE THE LATEST NWS HIGH
SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR
MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLANTIC WITH AXIS EXTENDING FROM
17N24W TO 10N20W...MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH
700 MB TROUGHING BETWEEN 13W-26W... FOCUSED ON A MID-LEVEL
MONSOONAL GYRE CENTERED ON A 1010 MB LOW CENTERED NEAR 10N17W.
THE WAVE IS EXPECTED TO CONTINUE PROPAGATING WESTWARD AND COME
INTO PHASE WITH A MID-LATITUDE 700 MB TROUGH CURRENTLY NEAR 28W-
32W. SCATTERED MODERATE CONVECTION IS FROM 06N-13N BETWEEN 15W-
29W.

A LOW AMPLITUDE TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH
AXIS EXTENDING FROM 18N39W TO 12N39W...MOVING W AT 10-15 KT. THE
WAVE COINCIDES WITH A 700 MB TROUGHING BETWEEN 36W-42W. GLOBAL
MODEL GUIDANCE ALSO INDICATED AN AREA OF MAXIMUM 850 MB RELATIVE
VORTICITY ALONG THE WAVE AXIS NEAR 15N. NO SIGNIFICANT
CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME AS AN AREA OF
SAHARAN DUST SURROUNDS THIS WAVE INHIBITING ANY SIGNIFICANT
ACTIVITY.

A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES WITH AXIS
EXTENDING FROM 17N51W TO 10N54W...MOVING W AT 15 KT. THE WAVE
COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 50W-60W. NO
SIGNIFICANT CONVECTION IS OBSERVED AT THIS TIME AS SAHARAN DUST
IS ALSO IN THE ENVIRONMENT OF THE WAVE.

A TROPICAL WAVE IS OVER THE W CARIBBEAN AND ENTERING CENTRAL
AMERICA WITH AXIS EXTENDING FROM 20N84W TO 10N84W...MOVING W AT
15 KT. THIS WAVE COINCIDES WITH WEAK AND SUBTLE 700 MB TROUGHING
BETWEEN 80W-88W. THE SCATTERED MODERATE CONVECTION CURRENTLY
SURROUNDING THIS WAVE IS MOSTLY RELATED TO AN UPPER-LEVEL LOW
ANCHORED OVER NICARAGUA AND EXTENDING ACROSS THE W CARIBBEAN.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM A 1010 MB LOW NEAR 10N16W TO
13N35W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
THAT POINT TO A 1012 MB LOW NEAR 11N45W TO 09N60W. ASIDE FROM
CONVECTION OCCURRING ACROSS THE LOW ALONG 17W...ISOLATED
MODERATE CONVECTION IS OBSERVED FROM 06N-13N BETWEEN 42W-52W.

...DISCUSSION...

GULF OF MEXICO...

AN UPPER-LEVEL HIGH ANCHORED OVER E TEXAS EXTENDS ACROSS WHOLE
THE BASIN. AT THE SURFACE...THE ATLANTIC RIDGE EXTENDS W
REACHING THE GULF WATERS AND ANCHORED BY A 1018 MB HIGH CENTERED
NEAR 27N84W. A SURFACE TROUGH EXTENDS ACROSS THE COAST OF
LOUISIANA SUPPORTING ISOLATED MODERATE CONVECTION N OF 29N
BETWEEN 89W-91W.ANOTHER CLUSTER OF CONVECTION PREVAILS ACROSS
PORTIONS OF NORTHERN FLORIDA AFFECTING THE NE GULF E OF 87W. AN
UPPER LEVEL LOW IS CURRENTLY CENTERED OVER NICARAGUA AND
EXTENDING ACROSS THE W CARIBBEAN AND FAR SOUTH GULF SUPPORTING
ISOLATED CONVECTION S OF 24N AND E OF 91W. SCATTEROMETER DATA
DEPICTS A LIGHT TO GENTLE ANTICYCLONIC FLOW PREVAILING ACROSS
THE BASIN. EXPECT SIMILAR WEATHER CONDITION TO PREVAIL OVER THE
NEXT 24 HOURS.

CARIBBEAN SEA...

AN ELONGATED UPPER-LEVEL LOW IS CENTERED OVER NICARAGUA AND
EXTENDING ACROSS THE W CARIBBEAN IS SUPPORTING ISOLATED MODERATE
CONVECTION ACROSS CUBA AND THE CARIBBEAN WATERS MAINLY W OF 77W.
TO THE E...AN UPPER-LEVEL ANTICYCLONE CENTERED NEAR GUADELOUPE
EXTENDS ACROSS THE E CARIBBEAN SUPPORTING SUBSIDENCE. WITH
THIS...FAIR WEATHER PREVAILS ACROSS THIS AREA. SCATTEROMETER
DATA DEPICTS GENTLE TO MODERATE TRADES ACROSS THE BASIN EXCEPT
MODERATE TO FRESH WINDS BETWEEN 68W-78W. DURING THE NEXT 24 HOURS
...THE PRIMARILY MARINE IMPACT WILL CONTINUE TO BE AN AREA OF
FRESH TO STRONG TRADES WITH THE EMBEDDED AREA OF GALE FORCE
WINDS N OF COLOMBIA. PLEASE REFER TOT HE SPECIAL FEATURES
SECTION FOR MORE DETAILS.

...HISPANIOLA...

DRY AIR AND STABLE CONDITIONS ALOFT CONTINUE TO SPREAD OVER THE
ISLAND FROM THE EAST DUE TO AN UPPER-LEVEL ANTICYCLONIC
CIRCULATION OVER GUADELOUPE AND EXTENDING ACROSS THE E
CARIBBEAN. SIMILAR WEATHER PATTERN IS EXPECTED OVER THE NEXT 24
HOURS.

ATLANTIC OCEAN...

A 1013 MB SURFACE LOW IS CENTERED NEAR 34N79W WITH A SURFACE
TROUGH EXTENDING FROM THE LOW CENTER ACROSS THE W ATLANTIC AND
INTO NE FLORIDA NEAR 30N81W. AN AREA OF UPPER-LEVEL DIFFLUENCE
PREVAILS ACROSS THE W ATLANTIC BETWEEN 71W-80W SUPPORTING
ISOLATED MODERATE CONVECTION MAINLY W OF 73W. A SURFACE TROUGH
WAS ANALYZED ACROSS THE NORTHERN BAHAMAS FROM 25N79W TO 28N76W.
ISOLATED CONVECTION IS OBSERVED ALONG THIS BOUNDARY BETWEEN 76W-
78W. TO THE E...A BROAD AREA OF HIGH PRESSURE EXTENDS ACROSS THE
REMAINDER OF THE BASIN CENTERED NEAR 36N50W. FAIR WEATHER
PREVAILS ACROSS THIS AREA. A PORTION OF THE ENERGY OF THE
TROPICAL WAVE CURRENTLY ALONG 53W FRACTURED N AND WAS ANALYZED
AS A SURFACE TROUGH WHICH EXTENDS FROM 19N49W TO 23N44W. NO
CONVECTION IS CURRENTLY RELATED TO THIS FEATURE. EXPECT SIMILAR
WEATHER CONDITIONS TO PREVAIL OVER THE NEXT 24 HOURS.

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

$$

ERA



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