[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161035
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU JUL 16 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1030 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS
APPROXIMATELY ALONG 36W FROM 08N TO 19N MOVING W AT 20-25 KT.
TPW IMAGERY INDICATES THE WAVE IS EMBEDDED IN A DEEP MOIST
ENVIRONMENT MAINLY E OF THE WAVE AXIS. METEOSAT SAL IMAGERY SHOW
SAHARAN DRY AIR ALSO IN THE ENVIRONMENT OF THIS WAVE ALONG THE
NORTHERN HALF OF IT WHICH REMAINS CONVECTION-FREE. SCATTERED
MODERATE CONVECTION IS S OF 13N BETWEEN 30W-40W SUPPORTED BY
UPPER-LEVEL DIVERGENCE AND THE PROXIMITY OF THE ITCZ AT THE
SURFACE.

A TROPICAL WAVE IS MOVING OVER THE E CARIBBEAN WITH AXIS
APPROXIMATELY ALONG 64W BETWEEN 06N AND 20N...MOVING AT 20 KT.
SSMI TPW AND METEOSAT IMAGERY DEPICT A MODERATELY MOIST
ENVIRONMENT SURROUNDING THIS WAVE BUT A STRONG DEEP-LAYER WIND
SHEAR AND SAHARAN DUST ARE KEEPING THIS AREA WITHOUT ANY
SIGNIFICANT CONVECTION...ONLY ISOLATED SHOWERS FROM 15N-17N
BETWEEN 65W-69W.

A TROPICAL WAVE IS OVER THE W CARIBBEAN WITH AXIS ALONG 82W
BETWEEN 10N AND 19N...MOVING W AT 15 KT. SSMI TPW IMAGERY
INDICATE THE WAVE IS EMBEDDED IN A MODERATELY MOIST ENVIRONMENT.
SCATTERED CONVECTION PREVAILS IN THE ENVIRONMENT OF THIS WAVE
MAINLY W OF 81W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH ENTERS THE ATLANTIC OCEAN THROUGH GUINEA
BISSAU NEAR 14N17W CONTINUING TO 12N21W. THE ITCZ EXTENDS FROM
THAT POINT TO 11N34W THEN RESUMES W OF A TROPICAL WAVE NEAR
10N38W TO 08N59W. ASIDE FROM THE CONVECTION ASSOCIATED WITH THE
TROPICAL WAVES...ISOLATED MODERATE CONVECTION IS OBSERVED S OF
THE ITCZ AXIS MAINLY W OF 56W AFFECTING PORTIONS OF GUYANA.

...DISCUSSION...

GULF OF MEXICO...

A BROAD SURFACE RIDGE COVERS A LARGE PORTION OF THE ATLANTIC
BASIN AND EXTENDS WESTWARD ACROSS SOUTH FLORIDA AND THE STRAITS
OF FLORIDA REACHING THE GULF OF MEXICO. A WEAK 1017 MB SURFACE
HIGH IS CENTERED NEAR 25N84W. A SURFACE TROUGH IS OVER THE BAY
OF CAMPECHE EXTENDING FROM 23N96W TO 20N96W. ALOFT...AN
ELONGATED UPPER-LEVEL LOW IS CENTERED OVER THE ISTHMUS OF
TEHUANTEPEC AND EXTENDS INTO THE BAY OF CAMPECHE SUPPORTING
SCATTERED CONVECTION S OF 20N BETWEEN 93W-96W. A MID TO UPPER-
LEVEL ANTICYCLONE OVER E TEXAS WITH RIDGE AXIS EXTENDS SE ACROSS
THE GULF TO NORTHERN FLORIDA. DEEP LAYERED SUBSIDENCE PREVAILS
OVER THE NW GULF SUPPORTING FAIR WEATHER. SCATTEROMETER DATA
DEPICTS A LIGHT ANTICYCLONIC FLOW PREVAILING ACROSS THE BASIN.
SURFACE RIDGING AND LIGHT FLOW WILL BE THE DOMINANT FEATURE
DURING THE NEXT FEW DAYS.

CARIBBEAN SEA...

A TROPICAL WAVE IS OVER THE W CARIBBEAN. PLEASE REFER TO THE
SECTION ABOVE FOR MORE DETAILS. STRONG DEEP LAYER WIND SHEAR
INHIBITS CONVECTION ACROSS THE MAJORITY OF THE BASIN. UPPER
LEVEL DIFFLUENCE PREVAILS ACROSS CENTRAL AMERICA WHICH SUPPORTS
SCATTERED MODERATE CONVECTION THAT IS CURRENTLY REACHING THE W
CARIBBEAN W OF 83W. OVER THE S-CENTRAL CARIBBEAN...THE PRESENCE
OF THE MONSOON TROUGH N OF PANAMA SUPPORTS ISOLATED MODERATE
CONVECTION S OF 11N. A SAHARAN AIRMASS ENGULFING THE NEXT
TROPICAL WAVE TO ENTER THE BASIN COVERS THE E CARIBBEAN E OF
70W...THUS INHIBITING SIGNIFICANT CONVECTION. SCATTEROMETER DATA
DEPICTS LIGHT TO GENTLE TRADES ACROSS THE W CARIBBEAN W OF 80W.
A PRESSURE GRADIENT BETWEEN THE RIDGE OF HIGH PRESSURE OVER THE
ATLANTIC EXTENDING ACROSS THE NORTHERN BASIN AND LOWER PRESSURE
OVER SOUTH AMERICA SUPPORTS FRESH TO STRONG TRADE WINDS ACROSS
THE CENTRAL CARIBBEAN MAINLY S OF 16N BETWEEN 70W-79W. MODERATE
TO FRESH TRADES PREVAIL ACROSS THE REMAINDER OF THE BASIN MAINLY
E OF 80W. THE NEXT TROPICAL WAVE WILL ENTER THE E CARIBBEAN
TONIGHT INCREASING MOISTURE AND ENHANCING SHOWERS OVER THE
LESSER ANTILLES AND PUERTO RICO.

HISPANIOLA...

FAIR WEATHER PREVAILS ACROSS THE ISLAND AT THIS TIME. TPW
IMAGERY DEPICTS A PATCH OF DRIER AIR OVER W PUERTO RICO AND THE
DOMINICAN REPUBLIC. UPPER-LEVEL SUBSIDENCE ALSO PREVAILS OVER
THIS AREA INHIBITING CONVECTION. THIS PATTERN WILL CONTINUE OVER
THE NEXT 24 HOURS.

ATLANTIC OCEAN...

TWO TROPICAL WAVES ARE OVER THE TROPICAL ATLANTIC ALONG 36W AND
64W. PLEASE SEE THE TROPICAL WAVES SECTION ABOVE FOR MORE
DETAILS. AN UPPER-LEVEL TROUGH ALONG THE E US COAST AND THE
PRESENCE OF AN UPPER-LEVEL LOW OVER THE BAHAMAS ARE GENERATING A
DIFFLUENT FLOW ACROSS THE W ATLANTIC W OF 70W. WITH
THIS...CLOUDINESS AND ISOLATED CONVECTION PREVAIL ACROSS W OF
70W. THE BERMUDA AZORES HIGH EXTENDS A RIDGE ACROSS THE CENTRAL
AND E TROPICAL ATLANTIC SUPPORTING FAIR WEATHER. A SURFACE
TROUGH EXTENDS OVER THE N-CENTRAL ATLANTIC FROM 27N54W TO 34N42W
WITH ISOLATED CONVECTION ALONG IT.

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

$$

ERA


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