Tropical Weather Discussion
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000
AXNT20 KNHC 281721
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE JUL 28 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...

A STRONG PRESSURE GRADIENT PREVAILS ACROSS THE CENTRAL CARIBBEAN
SUPPORTING GALE FORCE WINDS FROM 11N-13N BETWEEN 74W-78W. THESE
CONDITIONS ARE VERIFIED BY SCATTEROMETER DATA. EXPECT WINDS TO
DIMINISH BY THIS AFTERNOON. PLEASE REFER TO 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 TROPICAL ATLANTIC WITH AXIS
EXTENDING FROM 19N29W TO 13N34W...MOVING W AT 15 KT. THE WAVE
COINCIDES WITH BROAD AND VERY SUBTLE 700 MB TROUGHING BETWEEN
26W-32W WITH 700 MB RELATIVE VORTICITY FOCUSED NEAR THE SOUTHERN
EXTENT OF THE WAVE AXIS. NO CONVECTION IS RELATED TO THE WAVE AT
THIS TIME.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS EXTENDING
FROM 18N48W TO 09N50W...MOVING W AT 15 KT. THE WAVE COINCIDES
WITH BROAD 700 MB TROUGHING BETWEEN 48W-55W. NO SIGNIFICANT
CONVECTION IS OBSERVED AT THIS TIME DUE TO A BROAD AREA OF
SAHARAN DUST PREVAILING IN THE ENVIRONMENT OF THE WAVE.

A TROPICAL WAVE IS MOVING OVER THE CENTRAL CARIBBEAN WITH AXIS
EXTENDING FROM 18N71W TO 08N74W...MOVING W AT 15-20 KT. THIS
WAVE COINCIDES WITH 700 MB TROUGHING BETWEEN 70W-80W WITH NO
SIGNIFICANT CONVECTION AT THIS TIME DUE TO SAHARAN DUST
PREVAILING IN THE ENVIRONMENT OF THE WAVE.

A TROPICAL WAVE IS MOVING OVER CENTRAL AMERICA WITH AXIS
EXTENDING FROM 20N85W INTO THE EPAC NEAR 10N87W. THIS WAVE IS
MOVING W AT 15-20 KT. A BROAD 700 MB TROUGHING IS OBSERVED
BETWEEN 80W-88W. ISOLATED MODERATE CONVECTION PREVAILS S OF
18N AND W OF 85W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
16N17W TO 11N28W THEN RESUMES W OF A TROPICAL WAVE NEAR 11N31W
TO 10N41W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
THAT POINT TO 10N49 THEN RESUMES W OF A TROPICAL WAVE NEAR
09N51W TO 07N53W. SCATTERED MODERATE CONVECTION IS FROM 08N-14N
AND W 28W.

...DISCUSSION...

GULF OF MEXICO...

THE PERIPHERY OF AN UPPER-LEVEL HIGH CENTERED OVER NE TEXAS
EXTENDS ACROSS THE BASIN. AT THE SURFACE...THE RIDGE THAT
PREVAILS ACROSS THE ATLANTIC EXTENDS W REACHING THE E GULF
ANCHORED BY A 1018 MB SURFACE HIGH CENTERED NEAR 24N83W. TO THE
N...A 1013 MB SURFACE LOW PREVAILS ACROSS THE NE GULF WATERS
CENTERED NEAR 29N83W. A SURFACE TROUGH EXTENDS FROM THE LOW
CENTER TO 27N83W. SCATTERED MODERATE CONVECTION IS OBSERVED IN
THE VICINITY OF THE LOW/TROUGH MAINLY N OF 25N AND E OF 88W.
FAIR WEATHER PREVAILS ACROSS THE REMAINDER OF THE BASIN.
SCATTEROMETER DATA DEPICTS A LIGHT ANTICYCLONIC FLOW ACROSS THE
BASIN BECOMING VARIABLE NEAR THE CONVECTION OVER THE NE PORTION.
OVER THE NEXT 24 HOURS...EXPECT FOR THE LOW OVER THE NE GULF TO
MOVE ACROSS NORTHERN FLORIDA THEN INTO THE W ATLANTIC WITH
CONVECTION. SURFACE RIDGE WILL PREVAIL ACROSS THE BASIN.

CARIBBEAN SEA...

FAIR WEATHER PREVAILS ACROSS MOST OF THE BASIN A SAHARAN AIRMASS
PREVAILS AND STRONG DEEP-LAYER WIND SHEAR DOMINATES THE AREA.
ASIDE FROM THE ISOLATED CONVECTION OBSERVED OVER THE FAR W
CARIBBEAN RELATED TO A TROPICAL WAVE...A SMALL AREA WITH A FEW
SHOWERS IS OBSERVED NEAR THE LEEWARD ISLANDS AND PUERTO RICO
SUPPORTED BY AN UPPER-LEVEL LOW CENTERED NEAR 20N64W. A GALE
WARNING IS IN EFFECT FROM THE S CENTRAL CARIBBEAN MAINLY N OF
COLOMBIA. FOR MORE DETAILS...PLEASE REFER TO THE SPECIAL
FEATURES SECTION ABOVE. NO SIGNIFICANT CHANGES ARE EXPECTED OVER
THE NEXT 24 HOURS.

...HISPANIOLA...

MOSTLY CLEAR SKIES AND FAIR WEATHER PREVAIL ACROSS THE ISLAND.
THESE CONDITIONS WILL CONTINUE OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...

AN UPPER-LEVEL TROUGH EXTENDS ACROSS THE W ATLANTIC SUPPORTING A
STATIONARY FRONT CURRENTLY LOCATED FROM 33N67W TO 31N80W. WITH
THIS...A BROAD AREA OF SCATTERED MODERATE CONVECTION PREVAILS IN
THE VICINITY OF THIS FRONT MAINLY N OF 28N BETWEEN 68W-79W.
ISOLATED CONVECTION IS ALSO SPREADING ACROSS THE NORTHERN
BAHAMAS FROM 25N-27N BETWEEN 77W-80W. TO THE E...A SURFACE RIDGE
PREVAILS ACROSS THE REMAINDER OF THE BASIN ANCHORED BY A PAIR OF
SURFACE HIGHS...ONE NEAR 26N60W AND THE OTHER NEAR 35N30W. NO
SIGNIFICANT CONVECTION IS OBSERVED ACROSS THIS AREA.

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

$$

ERA



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