[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131018
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON JUL 13 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
1015 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLANTIC WITH AXIS EXTENDING FROM
18N21W TO 06N22Z...MOVING W AT 10 TO 15 KT. THE WAVE HAS A WEAK
CONVECTIVE AND SURFACE SIGNATURE...BUT IS EVIDENT IN THE TOTAL
PRECIPITABLE WATER IMAGERY AND THE GFS-BASED 700 MB TROUGH
DIAGNOSTICS. ISOLATED CONVECTION IS E OF THE WAVE AXIS MAINLY S
OF 10N AND E OF 23W.

A TROPICAL WAVE PREVAILS ACROSS THE CENTRAL ATLANTIC WITH AXIS
EXTENDING FROM 19N37W TO 07N37W...MOVING W AT 15 TO 20 KT. THIS
WAVE IS EASILY DISTINGUISHED IN IR SATELLITE IMAGERY FROM THE
SWIRL OF LOW-LEVEL CLOUDS...A MAXIMUM OF TPW IN THE ENVIRONMENT
OF THIS FEATURE...AND IN THE 700 MB TROUGH DIAGNOSTICS. A LARGE
AREA OF SAHARAN DUST IS SURROUNDING THIS WAVE...WHICH CONTINUES
INHIBITING SIGNIFICANT CONVECTION ALONG THIS WAVE AND MOST OF
THE ATLANTIC.

A TROPICAL WAVE IS AT ABOUT 50 NM E OF THE WINDWARD ISLANDS WITH
AXIS EXTENDING FROM 19N59W TO 07N61W...MOVING W AT AROUND 20 TO
25 KT. THIS WAVE COINCIDES WITH A RELATIVELY BROAD 700 MB TROUGH
DEPICTED BY THE GFS MODEL BUT NO CLEAR EVIDENCE AT THE SURFACE.
A RELATIVELY DRY AIR PREVAILS IN THE ENVIRONMENT OF THIS WAVE
WITH SAHARAN DUST MAINLY N OF 10N HENCE NO SIGNIFICANT
CONVECTION IS OBSERVED.

A TROPICAL WAVE EXTENDS ACROSS THE W CARIBBEAN WITH AXIS FROM
22N79W TO 09N81W...MOVING W AT 15 TO 20 KT. THIS WAVE IS A
LITTLE DIFFICULT TO DEPICT AS THE AREA IS BEING INFLUENCED BY AN
UPPER-LEVEL LOW CURRENTLY CENTERED OVER THE SOUTHERN BAHAMAS AND
EXTENDING S ACROSS THE W CARIBBEAN. SCATTERED MODERATE
CONVECTION IS OBSERVED S OF 16N BETWEEN 72W-84W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 09N13W TO
10N21W...THEN W OF A TROPICAL WAVE NEAR 09N24W TO 09N35W. THE
ITCZ BEGINS NEAR 07N39W TO 09N60W. SCATTERED MODERATE CONVECTION
PREVAILS BETWEEN 04N-10N AND E OF 21W. ISOLATED CONVECTION IS
DEVELOPING AT AROUND 100 NM N OF THE ITCZ AXIS MAINLY W OF 51W.

...DISCUSSION...

GULF OF MEXICO...

A 1019 MB SURFACE HIGH IS CENTERED OVER THE NW GULF NEAR 25N94W.
WITH THIS...A LIGHT ANTICYCLONIC FLOW PREVAILS ACROSS THE BASIN.
ISOLATED CONVECTION IS OBSERVED ACROSS THE E GULF MAINLY E OF
87W AS THE UPPER-LEVEL LOW THAT IS CENTERED OVER SOUTHERN
BAHAMAS EXTENDS NW AFFECTING THIS PORTION OF THE BASIN. OVER THE
NEXT 24 HOURS...EXPECT FOR THE SURFACE HIGH TO BECOME WEAK AND
DISSIPATE. ISOLATED TO SCATTERED CONVECTION IS EXPECTED ONCE
AGAIN ACROSS THE E GULF AS THE UPPER-LEVEL LOW PREVAILS ACROSS
THE SW ATLANTIC.

CARIBBEAN SEA...

A TROPICAL WAVE IS MOVING ACROSS THE W CARIBBEAN. FOR MORE
INFORMATION PLEASE REFER TO THE SECTION ABOVE. AN UPPER-LEVEL
LOW IS CENTERED OVER THE SOUTHERN BAHAMAS NEAR 24N74W AND
EXTENDING ITS TROUGH SW ACROSS THE W CARIBBEAN. UPPER-LEVEL
DIFFLUENCE PREVAILS E OF THIS FEATURE SUPPORTING SCATTERED LIGHT
TO MODERATE CONVECTION ACROSS THE NORTHERN CARIBBEAN WATERS
AFFECTING THE GREATER ANTILLES. ANOTHER AREA OF SCATTERED
MODERATE CONVECTION IS OBSERVED S OF 16N AFFECTING THE SOUTHERN
CARIBBEAN WATERS...CENTRAL AMERICA...AND PORTIONS OF NORTHERN
COLOMBIA. SCATTEROMETER DATA DEPICTS LIGHT TO GENTLE TRADES
ACROSS THE BASIN EXCEPT BETWEEN 66W-73W WHERE MODERATE WINDS
WERE REPORTED. OVER THE NEXT 24 HOURS...LITTLE CHANGE IS
EXPECTED TO THE TRADEWINDS. THE UPPER-LEVEL LOW IS EXPECTED TO
MOVE SLIGHTLY TO THE NE WHILE THE TROPICAL WAVE CONTINUES MOVING
W. THIS LIKELY WILL SHIFT CHANCES FOR DEEP CONVECTION TO THE
WESTERN CARIBBEAN.

...HISPANIOLA...

A BROAD UPPER-LEVEL LOW IS OVER THE SOUTHERN BAHAMAS AND
EXTENDING ACROSS THE W CARIBBEAN. WITH THIS...AN INCREASE IN
CLOUDINESS AND CONVECTION IS EXPECTED ONCE AGAIN TODAY. A
SIMILAR WEATHER PATTERN WILL PREVAIL AS THE UPPER-LEVEL LOW WILL
DRIFT NE OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...

THREE TROPICAL WAVES ARE OVER THE TROPICAL ATLANTIC. PLEASE
REFER TO THE SECTION ABOVE FOR MORE INFORMATION. AN UPPER-LEVEL
LOW IS CENTERED OVER THE SOUTHERN BAHAMAS NEAR 24N74W SUPPORTING
ISOLATED CONVECTION ACROSS THE W ATLANTIC MAINLY S OF 27N
BETWEEN 63W-77W. TO THE E...A 1025 MB SURFACE HIGH IS CENTERED
NEAR 32N39W AND EXTENDING ACROSS THE CENTRAL AND E ATLANTIC WITH
FAIR WEATHER. OVER THE NEXT 24 HOURS...EXPECT FOR THE UPPER-
LEVEL LOW OVER THE W ATLANTIC TO DRIFT NW ENHANCING CONVECTION.
NO CHANGE IS EXPECTED OVER THE REMAINDER OF THE BASIN.

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

$$

ERA
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