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AXNT20 KNHC 041731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT JUL 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1730 UTC.


...SPECIAL FEATURES...


...GALE IN THE CARIBBEAN...

A GALE WARNING CONTINUES IN EFFECT FOR THE SW CARIBBEAN FROM 11N- 13N BETWEEN 73W-78W THROUGH SUNDAY MORNING. THESE WINDS ARE GENERATED BY A TIGHT PRESSURE GRADIENT BETWEEN THE STRONG SURFACE RIDGE THAT PREVAILS OVER THE ATLANTIC AND THE LOWER PRESSURES OVER SOUTH AMERICA. SEE THE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS.


...TROPICAL WAVES...

A TROPICAL WAVE IS IN THE E TROPICAL ATLANTIC WITH AXIS EXTENDING FROM 16N33W TO 06N35W. THIS WAVE HAS BEEN MOVING W AT ABOUT 20-25 KT OVER THE PAST 24 HOURS. CURRENT METEOSAT SAL IMAGERY DEPICTS A BROAD AREA OF SAHARAN DUST SURROUNDING THIS WAVE WHICH IS INHIBITING SIGNIFICANT CONVECTION.

A TROPICAL WAVE IS IN THE CENTRAL TROPICAL ATLANTIC WITH AXIS EXTENDING FROM 13N45W TO 04N47W EXTENDS ALONG 43W FROM 5N-12N
...MOVING AT 15-20 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE EMBEDDED WITHIN LOW AMPLITUDE SURGE OF DEEP MOISTURE. ISOLATED CONVECTION IS ALONG 09N BETWEEN 45W-49W.

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN WITH AXIS EXTENDING FROM 18N74W TO 10N76W. THIS WAVE HAS MOVED W AT 20-25 KT OVER THE PAST 24 HOURS. CURRENT METEOSAT SAL IMAGERY DEPICTS A BROAD AREA OF SAHARAN DUST PREVAILING ACROSS THE CARIBBEAN AND IN THE ENVIRONMENT OF THIS WAVE...THUS INHIBITING CONVECTION.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLANTIC NEAR 14N17W TO 10N21W WHERE THE ITCZ BEGINS AND CONTINUES TO NEAR 09N34W THEN RESUMES W OF THE WAVE NEAR 08N37W TO 07N45W THEN AGAIN W OF A TROPICAL WAVE NEAR 07N49W TO 06N57W. ISOLATED CONVECTION PREVAILS IN THE PROXIMITY OF THE ITCZ AXIS BETWEEN 21W-23W AND 48W-54W.


...DISCUSSION...

GULF OF MEXICO...

AN UPPER-LEVEL LOW IS CENTERED OVER THE SOUTHERN GULF NEAR 22N89W AND EXTENDING ACROSS THE WHOLE BASIN. AN AREA OF UPPER- LEVEL DIFFLUENCE IS SUPPORTING SCATTERED MODERATE CONVECTION ALONG THE MEXICO COAST BETWEEN 20N-25N AND W OF 97W. AT THE SURFACE...A BROAD SURFACE HIGH CENTERED OVER THE ATLANTIC EXTENDING ITS RIDGE ACROSS W REACHING THE NORTHERN GULF WATERS. A 1021 MB SURFACE HIGH IS CENTERED OVER THE FLORIDA PENINSULA NEAR 28N81W. A LIGHT TO GENTLE ANTICYCLONIC FLOW PREVAILS ACROSS THE BASIN. OVER THE NEXT 24 HOURS...EXPECT FOR THE SURFACE RIDGE TO PERSIST.

CARIBBEAN SEA...

THE BASIN IS UNDER THE INFLUENCE OF A LARGE SAHARAN AIRMASS WHICH CONTINUES TO INHIBIT ANY SIGNIFICANT CONVECTION. A TROPICAL WAVE EXTENDS ACROSS THE CENTRAL CARIBBEAN...FOR MORE DETAILS PLEASE REFER TO THE SECTION ABOVE. AT THE SURFACE...THE HIGH PRESSURE THAT PREVAILS ACROSS THE ATLANTIC EXTENDS SW REACHING THE CARIBBEAN. THE PRESSURE GRADIENT BETWEEN THIS HIGH AND LOWER PRESSURES ACROSS SOUTH AMERICA IS GENERATING GALE FORCE WINDS ACROSS THE SOUTHERN CARIBBEAN. FOR MORE INFORMATION REFER TO THE SPECIAL FEATURES SECTION ABOVE. SCATTEROMETER DATA DEPICTS GENTLE TO MODERATE TRADES ACROSS THE REMAINDER OF THE AREA EXCEPT S OF 18N BETWEEN 71W-79W WHERE FRESH TO STRONG WINDS WERE ESTIMATED. OVER THE NEXT 24 HOURS...EXPECT A SIMILAR WEATHER PATTERN TO PREVAIL.


...HISPANIOLA...

FAIR WEATHER PREVAILS ACROSS THE ISLAND AS SAHARAN DUST CONTINUES INHIBITING ANY SIGNIFICANT CONVECTION. A TROPICAL WAVE IS S OF THE ISLAND NEAR THE WINDWARD PASSAGE. THIS WAVE WILL BRING A SLIGHT INCREASE IN MOISTURE ACROSS THE ISLAND WHICH COULD HELP IN THE DEVELOPMENT OF ISOLATED CONVECTION IN THE AFTERNOON. EXPECT A SIMILAR WEATHER PATTERN TO PREVAIL OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...

A SMALL UPPER-LEVEL RIDGE IS DEVELOPING ALONG 78W AND COMBINED WITH AN UPPER-LEVEL LOW CENTERED NEAR 26N70W...A DIFFLUENT FLOW IS SUPPORTING ISOLATED MODERATE CONVECTION ACROSS THE W ATLANTIC WATERS N OF 26N AND W OF 76W. AN AREA OF ISOLATED SHOWERS IS FROM 20N-28N BETWEEN 60W-70W. THE REMAINDER OF THE ATLANTIC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH N OF THE AREA NEAR 34N43W AND EXTENDING A RIDGE AXIS THROUGH 32N56W TO ACROSS CENTRAL FLORIDA AND INTO THE GULF OF MEXICO. NOAA/NESDIS AEROSOL PRODUCT AND VISIBLE SATELLITE IMAGERY INDICATES THAT A LARGE AND DENSE PLUMB OF SAHARAN DUST COVERS THE TROPICAL ATLANTIC N OF 11N. WITH THIS...NO SIGNIFICANT CONVECTION IS EXPECTED. OVER THE NEXT 24 HOURS...THE SURFACE RIDGE AND SAHARAN AIRMASS WILL PERSIST.

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

$$

ERA

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