Tropical Weather Discussion
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000
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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