[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI AUG 16 2013

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2322 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION ERIN IS CENTERED NEAR 17.7N 33.3W AT 16/2100
UTC OR ABOUT 545 NM W-NW OF THE CAPE VERDE ISLANDS MOVING W-NW
AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB AND THE
MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUST TO 40 KT.
CONVECTIVE ACTIVITY HAS SIGNIFICANTLY REDUCED...SAHARAN DRY AIR
INTRUSION TO THE CORE OF THE SYSTEM SEEMS TO BE ONE OF THE
FACTORS ACTING TO REDUCE IT. SCATTERED MODERATE CONVECTION AND
ISOLATED TSTMS ARE N-NW OF THE TROPICAL DEPRESSION CENTER FROM 18N-20N BETWEEN
32W-34W. SEE LATEST FORECAST/ADVISORY UNDER AWIPS/ WMO HEADERS
MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.

A TROPICAL WAVE ASSOCIATED WITH A 1009 MB LOW PRESSURE IS OVER
THE BAY OF CAMPECHE WITH AXIS EXTENDING FROM 25N91W...TO THE LOW
NEAR 21N91W TO 15N91W INLAND GUATEMALA. THE SYSTEM HAS BEEN
MOVING W-NW NEAR 10 KT WITHIN THE LAST TWELVE HOURS. RAINSHOWER
AND THUNDERSTORM ACTIVITY HAS INCREASED A LITTLE OVER THE PAST
FEW HOURS...HOWEVER STILL REMAINS EAST AND NORTHEAST OF THE LOW
CENTER ASSISTED BY SOUTHWESTERLY DEEP LAYER ENVIRONMENTAL WIND
SHEAR. SCATTERED MODERATE CONVECTION AND TSTMS ARE FROM 16N-28N
BETWEEN 85W-91W BEING ENHANCED BY AN AREA OF DIFFLUENT FLOW IN
THE MIDDLE TO UPPER LEVELS. ENVIRONMENTAL CONDITIONS COULD
BECOME MORE FAVORABLE FOR TROPICAL CYCLONE DEVELOPMENT IF THE
LOW MOVES TOWARD THE WEST OR WEST-NORTHWEST OVER THE NEXT COUPLE
OF DAYS. HOWEVER...IF IT TAKES A MORE NORTHWARD TRACK...IT COULD
FIND ITSELF INTO A LESS CONDUCIVE ENVIRONMENT FOR DEVELOPMENT.
CURRENTLY...THIS SYSTEM HAS A MEDIUM CHANCE...40 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
RAINSHOWERS AND TSTMS ARE EXPECTED TO CONTINUE TO IMPACT THE
CENTRAL AND WESTERN GULF.

...TROPICAL WAVES...
A TROPICAL WAVE EXTENDS AN AXIS FROM 21N51W TO 10N52W AND MOVES
WESTWARD NEAR 15-20 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW
THE WAVE CONTINUE EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT
AT THE LOWER LEVELS. HOWEVER...METEOSAT SATELLITE IMAGERY SHOW
SAHARAN DUST AND DRY AIR SPREADING OVER THE WAVE ENVIRONMENT
WHICH IS SUPPRESSING CONVECTION.

A TROPICAL WAVE IS MOVING ACROSS THE EASTERN CARIBBEAN. ITS AXIS
IS JUST EAST OF FAJARDO PUERTO RICO AND EXTENDS FROM 22N65W TO
09N65W...MOVING WEST NEAR 10-15 KT. TOTAL PRECIPITABLE WATER
IMAGERY INDICATE THE WAVE IS EMBEDDED IN A MODERATE MOIST
ENVIRONMENT N OF 17N AND A DRY ONE SOUTH OF THAT LATITUDE.
ISOLATED SHOWERS ARE BETWEEN THE NORTHERN COAST OF PUERTO RICO
AND 20N WITHIN 100 NM W OF THE WAVE AXIS.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE WESTERN COAST OF AFRICA
NEAR 10N14W TO 09N19W. THE AXIS RESUMES SW OF NOW TROPICAL
DEPRESSION ERIN ALONG 12N35W TO A 1010 MB LOW NEAR 11N45W TO
10N53W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 10
N53W TO 07N58W. BESIDES THE CONVECTION ASSOCIATED WITH THE
TROPICAL DEPRESSION AND THE WAVE ALREADY DISCUSSED...SCATTERED
MODERATE CONVECTION IS FROM 05N-13N E OF 21W. SIMILAR CONVECTION
IS FROM 06N-12N BETWEEN 35W-49W.

...DISCUSSION...

THE GULF OF MEXICO...
A TROPICAL WAVE ASSOCIATED WITH A 1009 MB LOW PRESSURE IS OVER
THE BAY OF CAMPECHE WITH AXIS EXTENDING FROM 25N91W...TO THE LOW
NEAR 21N91W TO 15N91W INLAND GUATEMALA. SCATTERED MODERATE
CONVECTION AND TSTMS ARE FROM 16N-28N BETWEEN 85W-91W BEING
ENHANCED BY AN AREA OF DIFFLUENT FLOW IN THE MIDDLE TO UPPER
LEVELS. A BROAD TROUGH IN THE MIDDLE TO UPPER LEVELS CONTINUE TO
SUPPORT A FRONTAL SYSTEM THAT AS OF 2100 UTC IS BEING ANALYZED
AS A STATIONARY FRONT ALONG 30N85W TO 30N87W 29N89W 29N93W. A
PREFRONTAL TROUGH IS OVER THE NE GULF EXTENDING FROM THE FLORIDA
PANHANDLE TO 29N84W 28N87W 28N90W. SCATTERED RAINSHOWERS
ASSOCIATED TO THE FRONTAL BOUNDARY AND THE TROUGH ARE N OF 27N E
OF 88W. CURRENTLY DRY AIR SUBSIDENCE FROM THE MIDDLE LEVELS IS
ASSISTING TO SUPPRESS CONVECTION IN THE WESTERN GULF W OF 93W.

THERE IS A MEDIUM CHANCE...40 PERCENT...OF TROPICAL CYCLONE
DEVELOPMENT FOR THE DISTURBANCE OVER THE BAY OF CAMPECHE WITHIN
A PERIOD OF 48 HOURS. SEE THE SPECIAL FEATURES SECTION FOR MORE
INFORMATION ABOUT THIS SYSTEM.

CARIBBEAN SEA...
OVER THE NW CARIBBEAN SEA...RAINSHOWERS AND ISOLATED TSTMS
ASSOCIATED TO THE DISTURBANCE OVER THE BAY OF CAMPECHE EXTENDS
TO WESTERN CUBA AND ADJACENT WATERS AS WELL AS N OF HONDURAS W
OF 85W. A TROPICAL WAVE IS MOVING ACROSS THE EASTERN CARIBBEAN.
ITS AXIS IS JUST EAST OF FAJARDO PUERTO RICO AND EXTENDS FROM
22N65W TO 09N65W. TOTAL PRECIPITABLE WATER IMAGERY INDICATE THE
WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT N OF 17N AND A
DRY ONE SOUTH OF THAT LATITUDE WHICH IS SUPPRESSING CONVECTION
IN THE EASTERN BASIN. OVER THE SOUTHERN CARIBBEAN...SCATTERED
MODERATE CONVECTION AND ISOLATED TSTMS ASSOCIATED WITH THE
MONSOON TROUGH AXIS ARE S OF A LINE FROM 14N74W TO 12N83W. OVER
THE REMAINDER BASIN...VERY DRY AIR IN THE LOWER AND MIDDLE
LEVELS IS HINDERING CONVECTION THUS PROVING FAIR WEATHER.

THE TROPICAL WAVE WILL CONTINUE A WESTWARD TRACK WITHIN A
MODERATE MOIST ENVIRONMENT MOSTLY N OF 17 N WHICH MAY ENHANCE
RAINSHOWERS IN PUERTO RICO TONIGHT AND HISPANIOLA DURING THE DAY
TOMORROW.

HISPANIOLA...
A DRY AIRMASS IS MOVING ACROSS HISPANIOLA SUPPORTING FAIR
WEATHER CONDITIONS. HOWEVER LATER TONIGHT THERE WILL BE A
MOISTURE INCREASE ASSOCIATED WITH A TROPICAL WAVE CURRENTLY
MOVING WESTWARD ACROSS PUERTO RICO. THIS WAVE IS EXPECTED TO
ENTER THE DOMINICAN REPUBLIC VERY EARLY ON SATURDAY AND EXIT THE
ISLAND IN THE EVENING. DURING THAT PERIOD RAINSHOWERS AND
TSTMS ARE POSSIBLE.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE EXTENDING FROM NORTHERN FLORIDA TO 18N IN
THE NW CARIBBEAN SEA AND A BROAD TROUGH THAT SUPPORTS THE
STATIONARY FRONT ACROSS THE NORTHERN GULF PROVIDE UPPER LEVEL
DIFFLUENCE OVER THE SW N ATLC. THIS UPPER LEVEL DIFFLUENT FLOW
IS SUPPORTING SCATTERED SHOWERS AND TSTMS N OF 24N W OF 74W.
OTHERWISE...ASIDE FROM THE TROPICAL WAVES AND TROPICAL
DEPRESSION ALREADY DISCUSSED ABOVE...A SURFACE RIDGE ANCHORED BY
A 1027 MB HIGH CENTERED NEAR 35N49W DOMINATES THE REMAINDER
BASIN THAT ALONG WITH DRY AIR IN THE LOWER AND MIDDLE LEVELS
SUPPORT FAIR WEATHER.

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

$$
RAMOS


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