[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130521
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLANTIC WITH AXIS EXTENDING FROM
18N19W TO 05N21Z...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...THE SENEGAL RAWINDSONDES...AND THE
GFS-BASED 700 MB TROUGH DIAGNOSTICS. ISOLATED CONVECTION IS E OF
THE WAVE AXIS MAINLY S OF 09N AND E OF 20W.

A TROPICAL WAVE PREVAILS ACROSS THE CENTRAL ATLANTIC WITH AXIS
EXTENDING FROM 19N35W TO 06N34W...MOVING W AT 10 TO 15 KT. THIS
WAVE IS EASILY DISTINGUISHED IN VISIBLE/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 ALSO PRESENT AROUND
THIS WAVE...WHICH CONTINUES INHIBITING SIGNIFICANT CONVECTION
ALONG THIS WAVE AND MOST OF THE ATLANTIC.

A TROPICAL WAVE IS AT ABOUT 250 NM E OF THE WINDWARD ISLANDS
WITH AXIS EXTENDING FROM 19N56W TO 05N58W...MOVING W AT AROUND
20 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
21N78W TO 08N79W...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 WHILE ISOLATED
CONVECTION PREVAILS N OF 19N BETWEEN 79W-85W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N17W TO
07N30W...WHERE THE ITCZ BEGINS AND CONTINUES THROUGH 06N54W AT
THE SOUTH AMERICA COAST. SCATTERED MODERATE CONVECTION IS FROM
04N TO 10N BETWEEN 12W AND 28W. ISOLATED MODERATE CONVECTION IS
FROM 04N TO 08N BETWEEN 18W AND 25W.

...DISCUSSION...

GULF OF MEXICO...

A 1018 MB SURFACE HIGH IS CENTERED OVER THE NW GULF NEAR 27N92W.
WITH THIS...A LIGHT ANTICYCLONIC FLOW PREVAILS ACROSS THE BASIN.
ISOLATED CONVECTION IS OBSERVED ACROSS THE E GULF MAINLY E OF
86W AS THE UPPER-LEVEL LOW THAT IS CENTERED OVER SOUTHERN
BAHAMAS EXTENDS NW REACHING 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 WILL PREVAIL
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 22N74W 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 WITH A GREATER INFLUENCE OVER
PUERTO RICO AT THIS TIME. ANOTHER AREA OF SCATTERED CONVECTION
IS OBSERVED S OF 14N 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 WAS NOTICED ACROSS THE ISLAND TODAY.
EXPECT A SIMILAR PATTERN TO CONTINUE AS THE UPPER-LEVEL LOW WILL
DRIFT NE OVER THE NEXT 24 HOURS. MAY CONTINUE TO PROMOTE SOME
DEEP CONVECTION DURING THE NEXT DAY OR SO.

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 22N74W SUPPORTING
ISOLATED CONVECTION ACROSS THE W ATLANTIC MAINLY S OF 28N
BETWEEN 64W-80W. TO THE E...A 1025 MB SURFACE HIGH IS CENTERED
NEAR 31N40W 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.
A SIMILAR WEATHER PATTERN WILL PREVAIL FOR THE REMAINDER OF THE
BASIN.

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

$$

ERA
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