[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071109
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI AUG 07 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 CENTRAL ATLC TROPICAL WAVE EXTENDS FROM 16N44W TO 09N41W
MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. THE WAVE
COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 37W AND 47W. DEEP
MOISTURE IS CONFINED S OF 12N ALONG THE ENVIRONMENT OF THE WAVE.
ISOLATED MODERATE CONVECTION IS FROM 08N TO 10N BETWEEN 39W AND
43W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
18N16W THROUGH A 1011 MB LOW NEAR 11N32W TO 08N46W...WHERE THE
ITCZ BEGINS AND CONTINUES TO THE S AMERICA COAST NEAR 09N61W.
ISOLATED MODERATE CONVECTION IS WITHIN 100 NM OF THE MONSOON
TROUGH AND ITCZ W OF 36W.

...DISCUSSION...

GULF OF MEXICO...

A SHORTWAVE TROUGH OVER THE EASTERN US HAS AN AXIS THAT EXTENDS
SW OVER THE NE GULF THIS MORNING. THE ENHANCED LIFT ASSOCIATED
WITH THE TROUGH IS SUPPORTING SCATTERED SHOWERS FROM 29N TO THE
N GULF COAST BETWEEN 83W AND 88W. THE SHORTWAVE WILL SHARPEN
ALONG THE EASTERN US TODAY AS A FRONTAL SYSTEM NEARS THE NE
GULF. THE APPROACH OF THIS FRONT WILL HELP TO SUPPORT CONVECTION
OVER THIS PORTION OF THE BASIN TODAY AND TONIGHT.
ELSEWHERE...GENERALLY FAIR WEATHER COVERS THE GULF BASIN THIS
MORNING. A SURFACE RIDGE AXIS EXTENDS FROM THE W ATLC TO S FL TO
NE MEXICO ALONG THE W GULF COAST. A CONVECTION FREE DIURNAL
SURFACE TROUGH EXTENDS FROM 23N92W TO 18N94W OVER THE SW GULF.
MAINLY GENTLE TO MODERATE ANTICYCLONIC SURFACE WINDS COVER THE
GULF OF MEXICO...WITH THE STRONGER WINDS OVER THE WESTERN GULF.

CARIBBEAN SEA...

AN UPPER LEVEL ANTICYCLONE CENTERED OVER THE SW CARIBBEAN
DOMINATES MUCH OF THE CARIBBEAN. DRY AIR AND SUBSIDENCE COVERS
THE BASIN E OF 80W S OF 16N AS NOTED IN THE LATEST WATER VAPOR
IMAGERY. ALSO NOTED IN WATER VAPOR IMAGERY IS AN AREA OF DYNAMIC
LIFT WITH ENHANCED MID LEVEL MOISTURE BETWEEN THE UPPER LEVEL
ANTICYCLONE OVER THE CARIBBEAN...AND AN UPPER LEVEL LOW OVER THE
CENTRAL ATLC. THE ENHANCED LIFT AND MOISTURE SUPPORTS ISOLATED
MODERATE CONVECTION FROM 18N TO 21N BETWEEN 74W AND 81W. THE
REMAINDER OF THE CARIBBEAN IS FREE OF DEEP CONVECTION. THE
PRESSURE GRADIENT BETWEEN W ATLC SURFACE RIDGING AND LOW
PRESSURE OVER COLOMBIA SUPPORTS FRESH TO STRONG TRADE WINDS OVER
THE S CENTRAL CARIBBEAN S OF 16N BETWEEN 69W AND 77W. GENTLE TO
MODERATE TRADE WINDS COVER THE REMAINDER OF THE BASIN. OVER THE
NEXT 24 HOURS CONVECTION WILL REMAIN POSSIBLE OVER THE NW
CARIBBEAN...WHERE BETTER MOISTURE AND LIFT WILL REMAIN. SHOWERS
AND CHANCES FOR CONVECTION WILL ALSO INCREASE TODAY OVER THE
NORTHERN LESSER ANTILLES AND VIRGIN ISLANDS AS A WEAK LOW AND
ACCOMPANYING SURFACE TROUGH MOVES NW FROM THE CENTRAL ATLC OVER
THE ISLANDS.

...HISPANIOLA...

MODERATE MOISTURE COMBINED WITH A BAND OF DYNAMIC LIFT BETWEEN
AN UPPER LOW OVER THE CENTRAL ATLC AND UPPER LEVEL RIDGING OVER
THE SW CARIBBEAN SUPPORTS ISOLATED MODERATE CONVECTION OVER SW
HAITI THIS MORNING. ADDITIONAL THUNDERSTORMS ARE FORECAST TO
DEVELOP THIS AFTERNOON ACROSS THE ISLAND WITH THE DAYTIME
HEATING. A SURFACE TROUGH MOVING ACROSS THE LESSER ANTILLES
TODAY MAY AFFECT HISPANIOLA BY SATURDAY WITH ENHANCED SHOWER AND
THUNDERSTORM ACTIVITY.

ATLANTIC OCEAN...

A MID TO UPPER LEVEL SHORTWAVE TROUGH ABOUT TO EMERGE OFF THE
EASTERN US COAST IS SUPPORTING SCATTERED THUNDERSTORMS N OF 28N
BETWEEN 74W AND 80W. A SURFACE RIDGE DOMINATES THE MAJORITY OF
THE SUBTROPICAL N ATLC ANCHORED BY A 1026 MB HIGH CENTERED NEAR
39N38W. THE RIDGE AXIS EXTENDS SW ACROSS THE W ATLC THROUGH A
1017 MB HIGH CENTERED NEAR 28N72W...AND CONTINUES W TO S FL. AN
UPPER LOW CENTERED NEAR 26N61W SUPPORTS A WEAKNESS IN THE
SURFACE RIDGE WITH A 1015 MB LOW CENTERED NEAR 27N60W. A SURFACE
TROUGH EXTENDS FROM 31N60W THROUGH THE LOW CENTER TO 22N60W. A
BROAD AREA OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
EXTENDS FROM 24N TO 31N BETWEEN 54W AND 69W...WITH A HIGHER
CONCENTRATION OF THUNDERSTORM COVERAGE BETWEEN 54W AND 58W.
FARTHER S...A 1012 MB LOW IS CENTERED NEAR 15N59W WITH A SURFACE
TROUGH EXTENDING FROM 17N59W THROUGH THE LOW CENTER TO 13N60W.
ISOLATED MODERATE CONVECTION IS FROM 15N TO 18N BETWEEN 57W AND
61W. OVER THE NEXT 24 HOURS CONVECTION WILL CONTINUE OVER THE W
ATLC N OF 28 W OF 70W...AND NEAR THE UPPER LOW.

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

$$
LATTO
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