[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161803 RRA
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN AUG 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

A 1011 MB LOW IS CENTERED OVER THE EASTERN ATLC NEAR
10N27W...SEVERAL HUNDRED MILES SOUTHWEST OF THE CAPE VERDE
ISLANDS. CONVECTION ASSOCIATED WITH THIS LOW HAS REMAINED
PERSISTENT THROUGH MUCH OF THE DAY TODAY...WITH NUMEROUS
MODERATE CONVECTION FROM 06N TO 13N BETWEEN 24W AND 31W.
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR SOME
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT SEVERAL DAYS AS IT
CONTINUES W AT 10 TO 15 KT. THE CHANCES OF THIS LOW DEVELOPING
INTO A TROPICAL CYCLONE OVER THE NEXT 48 HOURS IS MEDIUM.  FOR
ADDITIONAL INFORMATION...PLEASE REFER TO THE ATLC TROPICAL
WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20 FOR MORE
DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLC WITH AN AXIS EXTENDING FROM
19N26W...THROUGH THE LOW DISCUSSED IN THE SPECIAL FEATURES
SECTION...TO 07N27W...MOVING W AT 10 TO 15 KT. SSMI TPW SHOWS
HIGH MOISTURE S OF 13N WITH A BROAD AREA OF MODERATE MOISTURE N
OF 13N. NUMEROUS MODERATE CONVECTION IS FROM 06N TO 13N BETWEEN
24W AND 31W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AN AXIS EXTENDING
FROM 14N44W TO 05N46W...MOVING W AT 10 TO 15 KT. A 850 MB
VORTICITY MAXIMUM IS NOTED ALONG THE WAVE AXIS NEAR 10N45W. A
POLEWARD SURGE OF HIGH MOISTURE TO 12N IS NOTED IN SSMI TPW
ALONG THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS FROM 06N
TO 13N BETWEEN 40W AND 49W.

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AN AXIS
EXTENDING FROM 20N70W TO 11N72W...MOVING W AT AROUND 15 KT OVER
THE PAST 24 HOURS. THE NORTHERN PORTION OF THIS WAVE HAS
TRANSITIONED TO A SURFACE TROUGH THAT EXTENDS INTO THE W ATLC
WITH CONVECTION. STRONG SW SHEAR AND DRIER AIR S OF HISPANIOLA
IS LIMITING DEEP CONVECTION ALONG THE WAVE AXIS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N17W TO
A 1011 MB LOW NEAR 10N27W TO 08N35W...WHERE THE ITCZ BEGINS AND
CONTINUES TO 08N44W...THEN RESUMES EAST OF A CENTRAL ATLC
TROPICAL WAVE NEAR 08N47W TO 07N58W. OTHER THAN CONVECTION
ASSOCIATED WITH THE 1011 MB LOW DISCUSSED IN THE SPECIAL
FEATURES SECTION...AND THE TROPICAL WAVES...SCATTERED MODERATE
CONVECTION IS FROM 07N TO 12N BETWEEN 15W AND 20W.

...DISCUSSION...

GULF OF MEXICO...

A SHARP MID TO UPPER LEVEL TROUGH EXTENDS FROM THE TN VALLEY SW
TO CENTRAL MEXICO. DYNAMIC LIFT DOWNSTREAM OF THE TROUGH AXIS
SUPPORTS A SURFACE TROUGH FROM 24N97W TO 30N88W. THE ASCENT
ASSOCIATED WITH THE UPPER TROUGH AND CONVERGENCE WITH THE
SURFACE TROUGH IS INTERACTING WITH A VERY MOIST ATMOSPHERE TO
SUPPORT NUMEROUS THUNDERSTORMS WITH SCATTERED MODERATE
CONVECTION OVER MOST OF THE NORTHERN GULF OF MEXICO FROM 22N TO
31N BETWEEN 85W AND THE TEXAS AND MEXICO COASTS.  SURFACE
RIDGING OVER THE ATLC IS PRODUCING SE WINDS OF 10 TO 15 KT OVER
THE SOUTHERN GULF...AND WITH DEEP TROPICAL MOISTURE IN PLACE
SUPPORTS ISOLATED THUNDERSTORMS OVER THE SE GULF. OVER THE NEXT
24 HOURS THE UPPER TROUGH WILL REMAIN OVER TEXAS AND WILL
CONTINUE TO SUPPORT CONVECTION OVER THE NW GULF W OF 88W.

CARIBBEAN SEA...

AN UPPER LEVEL ANTICYCLONE CENTERED OVER THE SW CARIBBEAN
DOMINATES THE BASIN. UPPER LEVEL DIFFLUENCE UNDER THE CENTER OF
THE RIDGE SUPPORTS CLUSTERS OF MODERATE TO STRONG CONVECTION S
OF 12N W OF 79W. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN.
PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. THE
REMAINDER OF THE CARIBBEAN IS FREE OF DEEP CONVECTION. GENTLE TO
MODERATE TRADE WINDS COVER THE MAJORITY OF THE CARIBBEAN BASIN
WITH THE STRONGEST WINDS OVER THE S CENTRAL CARIBBEAN. OVER THE
NEXT 24 HOURS EXPECT CONVECTION TO SPREAD E OVER THE GREATER
ANTILLES AS THE TROPICAL WAVE CONTINUES W.

...HISPANIOLA...

A TROPICAL WAVE MOVING ACROSS THE ISLAND IS BRINGING WITH IT AN
INCREASE IN MOISTURE AND CHANCES FOR SHOWERS AND THUNDERSTORMS
ACROSS THE ISLAND THIS AFTERNOON. THE BEST CHANCE FOR HEAVY
RAINFALL WILL BE TONIGHT...AS MOIST SE FLOW BEHIND THE DEPARTING
WAVE SPREADS WEST ACROSS THE ISLAND. LOCALLY HEAVY RAINFALL AND
MUDSLIDES WILL BE POSSIBLE TONIGHT THROUGH MONDAY ASSOCIATED
WITH PERSISTENT RAIN THAT MAY OCCUR.

ATLANTIC OCEAN...

WEAK UPPER LEVEL DIFFLUENCE OVER THE BAHAMAS AND SURROUNDING
WATERS FROM AN EXTENSION OF UPPER LEVEL RIDGING OVER THE
CARIBBEAN IS INTERACTING WITH A MOIST AIRMASS TO SUPPORT
SCATTERED SHOWERS THUNDERSTORMS FROM 25N TO 31N W OF
77W...INCLUDING THE NORTHERN BAHAMAS. A SURFACE TROUGH EXTENDS
FROM HISPANIOLA TO NEAR 23N69W AND IS ASSOCIATED WITH THE
NORTHERN PORTION OF A TROPICAL WAVE MOVING W ACROSS THE
CARIBBEAN. SW SHEAR IS DISPLACING CONVECTION TO THE NE OF THE
TROUGH AXIS. HOWEVER...THE DEEP MOISTURE IN PLACE SUPPORTS
CLUSTERS OF MODERATE AND ISOLATED STRONG CONVECTION FROM 18N TO
23N BETWEEN 63W AND 69W. THREE SURFACE TROUGHS ARE OVER THE
CENTRAL ATLC. THE WESTERNMOST TROUGH EXTENDS FROM 26N64W AND NE
OUT OF OUR AREA OF DISCUSSION. ISOLATED THUNDERSTORMS ARE FROM
25N TO 27N BETWEEN 61W AND 66W. THE NEXT SURFACE TROUGH EXTENDS
FROM 14N55W TO 24N49W. NO DEEP CONVECTION IS ASSOCIATED WITH THIS
TROUGH. THE EASTERNMOST TROUGH EXTENDS FROM 27N39W TO 31N35W
WITH NO DEEP CONVECTION BEING OBSERVED. TWO TROPICAL WAVES AND A
SPECIAL FEATURES 1011 MB LOW ARE OVER THE TROPICAL NORTHERN
ATLC. PLEASE REFER TO THE TROPICAL WAVES SECTION AND SPECIAL
FEATURES SECTION FOR MORE DETAILS. EXPECT CONVECTION ASSOCIATED
WITH THE SURFACE TROUGH NEAR HISPANIOLA TO CONTINUE TO SPREAD
WEST TO WEST-NORTHWEST ACROSS THE SE BAHAMAS THROUGH
MONDAY.

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

$$
LATTO
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