Tropical Weather Discussion
Issued by NWS

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000
AXNT20 KNHC 052349
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN JUL 05 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
2345 UTC.

...SPECIAL FEATURES...

...GALE IN THE CARIBBEAN...

A GALE WARNING IS IN EFFECT FOR THE SW CARIBBEAN FROM 11N TO
13.5N BETWEEN 73W AND 78W THROUGH MONDAY MORNING. THESE WINDS
ARE GENERATED BY A TIGHT PRESSURE GRADIENT BETWEEN THE STRONG
SURFACE RIDGE OVER THE ATLANTIC AND LOWER PRESSURES OVER SOUTH
AMERICA. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO
HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE CENTRAL TROPICAL ATLANTIC WITH AXIS
EXTENDING FROM 14N47W TO 06N48W. THIS WAVE HAS MOVED W AT AROUND
25 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE WATER
IMAGERY SHOWS THE WAVE IS EMBEDDED WITHIN AN SURGE OF MODERATE
MOISTURE S OF 10N. ENHANCED METEOSAT IMAGERY SHOWS SAHARAN DUST
ACROSS THE NORTHERN PORTION OF THE WAVE MAINLY N OF 10N WHICH IS
INHIBITING CONVECTION. SCATTERED MODERATE CONVECTION PREVAILS S
OF 10N BETWEEN 46W-52W. THIS CONVECTION IS PARTIALLY ASSOCIATED
ALSO WITH THE PROXIMITY OF THE ITCZ.

A TROPICAL WAVE IS AT ABOUT 200 NM E OF THE LESSER ANTILLES WITH
AXIS EXTENDING FROM 17N56W TO 08N58W. THIS WAVE IS MOVING W NEAR
20 KT. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS
EMBEDDED WITHIN DEEP HIGH MOISTURE MAINLY S OF 11N. A DRY
SAHARAN AIRMASS PREVAILS N OF 12N INHIBITING CONVECTION.
SCATTERED LIGHT TO MODERATE CONVECTION IS S OF 10N BETWEEN 54W-
62W. LIKE THE PREVIOUS WAVE DISCUSSED...THIS CONVECTION IS
PARTIALLY ASSOCIATED WITH THE PROXIMITY OF THE ITCZ.

A TROPICAL WAVE IS CURRENTLY OVER CENTRAL AMERICA WITH AXIS
EXTENDING FROM 18N84W TO 11N84W. THIS WAVE IS MOVING W AT AROUND
20 KT. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS
EMBEDDED WITHIN A SURGE OF MODERATE MOISTURE. ISOLATED
CONVECTION IS ALONG 15N BETWEEN 82W-86W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA REACHING THE TROPICAL
ATLANTIC NEAR 18N16W TO 10N23W TO 08N26W WHERE THE ITCZ BEGINS
AND CONTINUES TO 07N46W...THEN RESUMES W OF A TROPICAL WAVE NEAR
07N49W TO 07N57W. SCATTERED MODERATE CONVECTION IS WITHIN 50 NM
N OF THE ITCZ AXIS BETWEEN 42W-56W.

...DISCUSSION...

GULF OF MEXICO...

AN UPPER-LEVEL LOW IS CENTERED OVER THE SOUTHERN GULF NEAR
23N88W AND EXTENDING ACROSS THE BASIN. WITH THIS...UPPER-LEVEL
DIFFLUENCE PREVAILS ACROSS THE E GULF SUPPORTING SCATTERED
MODERATE CONVECTION MAINLY E OF 88W. ANOTHER AREA OF UPPER-LEVEL
DIFFLUENCE IS SUPPORTING SCATTERED MODERATE CONVECTION ACROSS
THE GULF COAST STATES E OF TEXAS AND THE N GULF WATERS N OF 29N.
AT THE SURFACE...THE RIDGE THAT PREVAILS ACROSS THE ATLANTIC
EXTENDS W ACROSS THE NORTHERN GULF WATERS. AN ANTICYCLONIC LIGHT
TO GENTLE FLOW PREVAILS ACROSS THE BASIN. OVER THE NEXT 24
HOURS...EXPECT CONVECTION TO DECREASE OVER THE NE GULF TONIGHT
WITH MAINLY ISOLATED TO SCATTERED WEAK CONVECTION OVER THE
EASTERN GULF ON MONDAY.

CARIBBEAN SEA...

THE UPPER-LEVEL DIFFLUENCE THAT PREVAILS ACROSS THE E GULF ALSO
EXTENDS ACROSS THE W CARIBBEAN AND W CUBA SUPPORTING ISOLATED
CONVECTION MAINLY W OF 80W. A TROPICAL WAVE IS OVER THE SW
CARIBBEAN...PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE
DETAILS. ENHANCED METEOSAT IMAGERY DEPICTS A SAHARAN AIRMASS
DOMINATING THE CENTRAL AND E CARIBBEAN INHIBITING SIGNIFICANT
CONVECTION. A STRONG PRESSURE GRADIENT BETWEEN THE HIGH PRESSURE
OVER THE SUBTROPICAL NORTHERN ATLANTIC AND LOWER PRESSURES OVER
S AMERICA SUPPORTS MODERATE TO FRESH WINDS S OF 18N BETWEEN 70W-
80W WITH GALE FORCE WINDS OVER A PORTION OF THE SW CARIBBEAN.
PLEASE SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS. THE
PRESSURE GRADIENT IS EXPECTED TO WEAKEN SLIGHTLY ON MONDAY AS
THE HIGH PRESSURE OVER THE ATLANTIC ERODES FROM THE W WITH THE
APPROACH OF AN UPPER-LEVEL TROUGH. THIS WILL BE SUFFICIENT TO
BRING WINDS BELOW GALE FORCE OVER THE SW CARIBBEAN BY LATE
MONDAY MORNING. A TROPICAL WAVE WILL MOVE OVER THE LEEWARD
ISLANDS OVER THE NEXT 24 HOURS.

...HISPANIOLA...

DRY AIR AND SAHARAN DUST PREVAIL OVER THE ISLAND AND THE
CARIBBEAN BASIN. EXPECT THIS CONDITIONS TO CONTINUE OVER THE
NEXT 24 HOURS. A TROPICAL WAVE CURRENTLY APPROACHING THE
WINDWARD/LEEWARD ISLANDS MAY BRING AN INCREASE IN MOISTURE
ACROSS THE AREA SUPPORTING SHOWER AND THUNDERSTORM ACTIVITY BY
LATE MONDAY.

ATLANTIC OCEAN...

AN UPPER-LEVEL LOW IS CENTERED NEAR 27N69W. THIS FEATURE...
COMBINED WITH THE UPPER-LEVEL LOW OVER THE SOUTHERN GULF OF
MEXICO...IS SUPPORTING A DIFFLUENT FLOW BETWEEN THESE CENTERS
WHICH IS GENERATING SCATTERED CONVECTION ACROSS THE FLORIDA
PENINSULA AND W ATLANTIC MAINLY W OF 75W. AT THE SURFACE...A
BROAD AREA OF HIGH PRESSURE EXTENDS ACROSS THE WHOLE BASIN
CENTERED NEAR 34N42W. A SAHARAN AIRMASS ALSO EXTENDS ACROSS THE
BASIN INHIBITING ANY SIGNIFICANT CONVECTION...WITH HIGHER
CONCENTRATION E OF 50W. TWO TROPICAL WAVES ARE OVER THE TROPICAL
NORTHERN ATLANTIC. PLEASE SEE THE TROPICAL WAVES SECTION FOR
MORE DETAILS.

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

$$

ERA



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