Tropical Weather Discussion
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000
AXNT20 KNHC 010604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT AUG 01 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
0545 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS IN THE E TROPICAL ATLC WITH AXIS JUST E OF
THE CAPE VERDE ISLANDS NEAR 22W...MOVING W AT 10-15 KT OVER THE
PAST 18 HOURS. METEOSAT ENHANCED IMAGERY SHOW SAHARAN DRY AIR
AND DUST IN THE NORTHERN WAVE ENVIRONMENT WHERE NO CONVECTION IS
OBSERVED. HOWEVER...SOUTH OF THE MONSOON TROUGH...ABUNDANT
MOISTURE AND A DIFFLUENT WIND ENVIRONMENT ALOFT SUPPORT A
CLUSTER OF MODERATE/ISOLATED STRONG CONVECTION FROM 11N TO 14N
BETWEEN 18W AND 25W.

A TROPICAL WAVE IS IN THE W TROPICAL ATLC WITH AXIS NEAR
52W...MOVING W AT 20 KT. THE TOTAL PRECIPITABLE WATER IMAGERY
SHOW SHALLOW MOISTURE BEHIND THE WAVE AXIS AND DRY AIR AHEAD OF
IT. THE WAVE IS DEVOID OF CONVECTION AS SAHARAN DRY AIR AND DUST
COVER THE ENTIRE WAVE ENVIRONMENT.

A TROPICAL WAVE IS IN THE W CARIBBEAN WITH AXIS NEAR 80W...
MOVING W AT 15 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE
WATER IMAGERY SHOWS THE WAVE IS ASSOCIATED WITH A SURGE OF DEEP
MOISTURE. HOWEVER...STRONG DEEP LAYER WIND SHEAR OVER THE SW
CARIBBEAN IS LIMITING THE CONVECTION TO ISOLATED SHOWERS AND
TSTMS AHEAD OF THE WAVE AXIS S OF 17N.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E
TROPICAL ATLC NEAR 20N16W TO E OF THE EASTERN MOST TROPICAL WAVE
NEAR 15N20W TO A 1009 MB LOW NEAR 12N35W SW TO 08N49W. THE ITCZ
BEGINS NEAR 08N50W AND CONTINUES TO COASTAL GUYANA NEAR 07N57W.
ASIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE NEAR
THE CAPE VERDE ISLANDS...SCATTERED MODERATE CONVECTION IS FROM
07N-14N BETWEEN 32W-39W AND FROM 06N-10N BETWEEN 41W-53W.

...DISCUSSION...

GULF OF MEXICO...

DEEP MOISTURE ASSOCIATED WITH A LOW PRESSURE SYSTEM OVER THE SE
CONUS EXTENDS ACROSS THE NORTHERN GULF WHERE A 1012 MB LOW IS
ANALYZED NEAR 29N86W ALONG WITH A STATIONARY FRONT EXTENDING
FROM 31N86W TO THE LOW TO 28N90W TO 29N95W. A DIFFLUENT WIND
ENVIRONMENT ALOFT OVER THE NORTH-CENTRAL AND NE BASIN BEING
GENERATED BY THE SE PERIPHERY OF AN UPPER RIDGE SUPPORT
SCATTERED MODERATE CONVECTION AND TSTMS N OF 26N E OF 93W. OVER
THE NW BASIN...A 1015 MB HIGH PREVAILS. A MIDDLE-LEVEL LOW OVER
THE SAME REGION ALONG WITH THE MOISTURE REFERENCED ABOVE SUPPORT
SCATTERED MODERATE CONVECTION FROM 25N-27N W OF 95W.
OTHERWISE...SURFACE RIDGING DOMINATES THE SE GULF WHERE
SCATTERED SHOWERS AND TSTMS ARE OBSERVED. WINDS ARE VARIABLE AND
LIGHT OVER THE ENTIRE BASIN...EXCEPT THE NE GULF WHERE WINDS ARE
FROM THE SW RANGING FROM 15 KT TO 20 KT. FRONT WILL MEANDER OVER
THE N GULF THROUGH THE WEEKEND. THE SURFACE RIDGE WILL CONTINUE
TO BUILD BACK ACROSS THE GULF THROUGH MON.

CARIBBEAN SEA...

AN UPPER-LOW IS OVER THE NW CARIBBEAN...WHICH ALONG WITH SHALLOW
MOISTURE SUPPORT ISOLATED SHOWERS AND TSTMS N OF 18N BETWEEN 80W
AND 85W. AN UPPER RIDGE DOMINATES ACROSS THE REMAINDER BASIN. A
TROPICAL WAVE IS BEING ANALYZED OVER THE SW CARIBBEAN WITH AXIS
NEAR 80W...WHICH IS ENHANCING ISOLATED SHOWERS AND TSTMS AHEAD
OF ITS AXIS. SEE TROPICAL WAVES SECTION FOR FURTHER DETAILS. EVEN
THAT MODERATE MOISTURE IS OBSERVED IN SSMI TPW IMAGERY ACROSS
THE CENTRAL AND SE CARIBBEAN...STRONG DEEP LAYER WIND SHEAR
ACROSS THE REGION SUPPORT STABLE CONDITIONS. NE TO E WINDS OF 20
TO 25 KT ARE FROM 11N TO 14N BETWEEN 69W AND 77W WITH SEAS TO 8
FT. TRADES OF 15 KT ARE W OF 77W. THE TROPICAL WAVE WILL MOVE
INLAND CENTRAL AMERICA SAT NIGHT. THE NEXT TROPICAL WAVE WILL
ENTER THE CARIBBEAN SUN.

...HISPANIOLA...

SHALLOW MOISTURE ASSOCIATED WITH THE PASSAGE OF A TROPICAL WAVE IS
ACROSS THE ISLAND SUPPORTING CLOUDINESS. HOWEVER...NO CONVECTION
IS OBSERVED AT THIS TIME. MOISTURE IS EXPECTED TO DECREASE SAT
MORNING AS SAHARAN DRY AIR AND DUST START TO MOVE ACROSS THE
ISLAND AHEAD OF THE NEXT TROPICAL WAVE TO ENTER THE CARIBBEAN
SUNDAY NIGHT.

ATLANTIC OCEAN...

A MIDDLE TO UPPER LEVEL LOW IS OVER THE SW N ATLC ALONG WITH
SHALLOW MOISTURE AHEAD OF A FRONTAL SYSTEM OVER THE SE CONUS.
LOW LEVEL MOISTURE CONVERGENCE IN THIS REGION AND A DIFFLUENT
WIND ENVIRONMENT ALOFT BEING GENERATED BY UPPER RIDGING ACROSS
THE GULF OF MEXICO SUPPORT SCATTERED MODERATE CONVECTION AND
TSTMS N OF 23N W OF 75W. SURFACE RIDGING DOMINATES ACROSS THE
REMAINDER BASIN...THUS FAVORING FAIR WEATHER. FOR TROPICAL WAVES
INFORMATION SEE SECTION ABOVE.

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

$$
NR


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