[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151756
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU AUG 15 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...
TROPICAL STORM ERIN IS CENTERED NEAR 14.4N 26.5W AT 15/1500 UTC
OR ABOUT 100 NM WSW OF BRAVA IN THE CAPE VERDE ISLANDS MOVING W-
NW AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB.
MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUST TO 45 KT.
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 12N-
15N BETWEEN 25W-28W. SEE LATEST FORECAST/ADVISORY UNDER AWIPS/
WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.

TROPICAL WAVE EXTENDS FROM 18N88W TO 25N86W MOVING W-NW AT 10
KT. A 1010 MB LOW IS CENTERED ALONG THE YUCATAN PENINSULA COAST
NEAR 19N88W AND THE SYSTEM REMAINS ON THE WESTERN PERIPHERY OF
AN UPPER LEVEL ANTCYCLONIC CIRCULATION CENTERED OVER WESTERN
CUBA. LOW-LEVEL MOISTURE CONVERGENCE EAST OF THE TROPICAL WAVE
AXIS AND A FAVORABLE UPPER LEVEL DIFFLUENT ENVIRONMENT OVER THE
NW CARIBBEAN IS GENERATING SCATTERED MODERATE CONVECTION FROM
16N-26N BETWEEN 84W-89W. AS THE WAVE TRACKS GENERALLY WESTWARD
INTO THE WESTERN GULF OF MEXICO THROUGH THE WEEKEND...NUMEROUS
SHOWERS AND TSTMS ARE EXPECTED TO IMPACT THE YUCATAN PENINSULA
AND SW GULF OVER THE NEXT 24 TO 48 HOURS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 12N44W TO 19N44W MOVING W AT 10-15
KT. THE WAVE REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AND IS
LARGELY CONVECTION FREE DUE TO THE SAHARAN AIR LAYER ACROSS THE
CENTRAL ATLC.

TROPICAL WAVE EXTENDS FROM 12N57W TO 20N57W MOVING W AT 10-15
KT. THE WAVE IS LIKELY ENERGY THAT EMERGED OFF THE AFRICAN COAST
DAYS AGO AND MERGED WITH MID-LATITUDE ENERGY DIVING
SOUTHWESTWARD ACROSS THE CENTRAL ATLC BETWEEN 35W-55W IN THE
PAST 24 TO 48 HOURS. WHILE THE WAVE IS MOVING WITHIN A STRONG
SAHARAN AIR LAYER...NO SIGNIFICANT DEEP CONVECTION IS NOTED IN
THE VICINITY OF THE WAVE AXIS HOWEVER ISOLATED LOW-TOPPED
SHOWERS ARE POSSIBLE FROM 13N-22N BETWEEN 53W-61W. THIS ACTIVITY
WILL BE MOVING ACROSS THE LESSER ANTILLES AND EASTERN CARIBBEAN
THROUGH THE WEEKEND.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 12N28W TO 11N31W TO 13N42W TO
09N52W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
09N52W TO 07N59W. SCATTERED MODERATE CONVECTION IS FROM 07N-12N
BETWEEN 23W-47W. ISOLATED MODERATE CONVECTION IS WITHIN 75 NM
EITHER SIDE OF A LINE FROM 12N48W TO 09N57W.

...DISCUSSION...

GULF OF MEXICO...
A NARROW MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 24N87W OVER
THE CENTRAL GULF AND REMAINS IN BETWEEN TWO UPPER LEVEL
ANTICYCLONIC CIRCULATION CENTERS...ONE OVER THE NW GULF NEAR
27N94W...AND THE OTHER CENTERED OVER THE NW CARIBBEAN SEA NEAR
20N84W. WATER VAPOR IMAGERY INDICATES PLENTY OF MIDDLE TO UPPER
LEVEL DIFFLUENCE ON THE EASTERN PERIPHERY OF THE TROUGHING AND
THIS DIFFLUENCE ALONG WITH LOW-LEVEL MOISTURE CONVERGENCE
ASSOCIATED WITH A TROPICAL WAVE ALONG 87W IS GENERATING
SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS S OF 27N BETWEEN
80W-88W...INCLUDING THE SOUTHERN FLORIDA PENINSULA...AND FLORIDA
STRAITS. TO THE NORTH...WATER VAPOR IMAGERY ALSO INDICATES
BROADER MIDDLE TO UPPER LEVEL LONGWAVE TROUGHING THAT SUPPORTS A
WEAK STATIONARY FRONT ANALYZED FROM SOUTHERN GEORGIA NEAR 32N83W
W-SW TO THE TEXAS GULF COAST NEAR 28N97W. A PRE-FRONTAL SURFACE
TROUGH IS ALSO NOTED FROM THE MISSISSIPPI RIVER DELTA NEAR
29N89W TO 28N94W. BOTH BOUNDARIES ARE PROVIDING FOCUS FOR WIDELY
SCATTERED SHOWERS AND ISOLATED TSTMS N OF 27N W OF 84W. THE
REMAINDER OF THE GULF BASIN IS UNDER THE INFLUENCE OF A VERY
WEAK SURFACE RIDGE EXTENDING FROM A 1015 MB HIGH CENTERED NEAR
27N94W TO A 1017 MB HIGH CENTERED INLAND OVER EAST-CENTRAL
MEXICO NEAR 20N98W. THE TROPICAL WAVE AND ASSOCIATED LOW
PRESSURE AREA IS EXPECTED TO MOVE W-NW THROUGH THE WEEKEND WITH
GENERAL SURFACE TROUGHING EXTENDING FROM THE COASTAL GULF PLAINS
TO THE SW GULF.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE NW
CARIBBEAN NEAR 19N84W THAT IS PROVIDING AN OVERALL DIFFLUENT
ENVIRONMENT IN THE VICINITY OF A TROPICAL WAVE AND ASSOCIATED
SURFACE LOW LOCATED ALONG THE YUCATAN PENINSULA COAST NEAR
19N88W. LOW-LEVEL MOISTURE CONVERGENCE EAST OF THE TROPICAL WAVE
AND THE FAVORABLE UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED
SHOWERS AND TSTMS GENERALLY N OF 16N W OF 79W. THE STRONGEST OF
THIS ACTIVITY IS LOCATED WITHIN 180 NM OF THE NE QUADRANT OF THE
SURFACE LOW. THE 1010 MB LOW IS EXPECTED TO CONTINUE MOVING W-NW
ACROSS INLAND PORTIONS OF THE YUCATAN PENINSULA OVER THE NEXT 12
TO 24 HOURS AND EMERGE INTO THE WATERS OF THE SW GULF OF MEXICO.
FARTHER SE...WATER VAPOR IMAGERY INDICATES NORTHEASTERLY FLOW
ALOFT WEST OF A LINE FROM 18N69W TO 09N76W THAT IS PROVIDING AN
OVERALL DRY AND SUBSIDENT ATMOSPHERE FOR THE CENTRAL CARIBBEAN.
SKIES CURRENTLY ARE CLEAR WITH ONLY A FEW PASSING LOW-LEVEL
CUMULUS OR HIGH-LEVEL CIRRUS CLOUDS. EAST OF THE AFOREMENTIONED
LINE...FLOW ALOFT SHIFTS MORE SOUTHERLY AND IS DRY ALOFT. THE
EASTERN CARIBBEAN AND LESSER ANTILLES LIE WITHIN AN AREA OF E-NE
WINDS ON THE WESTERN PERIPHERY OF AN APPROACHING TROPICAL WAVE
ALONG 57W. LOW-LEVEL MOISTURE WILL BE ON THE INCREASE FOR THE
ISLANDS AND EASTERN CARIBBEAN OVER THE NEXT 24 TO 36 HOURS...
HOWEVER WILL BE GENERALLY LIMITED TO LOW-TOPPED SHOWERS AS ANY
SIGNIFICANT DEEP CONVECTION WILL LIKELY BE SUPPRESSED DUE TO THE
PRESENCE OF A SAHARAN AIR LAYER.

HISPANIOLA...
CURRENTLY SKIES REMAIN CLEAR WITH FAIR CONDITIONS THIS AFTERNOON
AS DRIER AIR AND SUBSIDENCE ALOFT CONTINUES TO MOVE IN FROM THE
EAST AS NOTED ON WATER VAPOR IMAGERY. THE DRY AIR ALOFT
STRETCHES WELL INTO THE CENTRAL ATLC...HOWEVER...THE APPROACH OF
A TROPICAL WAVE ALONG 57W WILL INCREASE MOISTURE AND CLOUDINESS
ACROSS THE REGION OVER THE UPCOMING WEEKEND WITH THE A HIGHER
POSSIBILITY OF SHOWER AND THUNDERSTORM ACTIVITY.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE IS NOTED ON WATER VAPOR IMAGERY GENERALLY S
OF 30N W OF 73W AND IS PROVIDING AN UPPER LEVEL DIFFLUENT
ENVIRONMENT OVER THE SW NORTH ATLC THIS AFTERNOON. LOW-LEVEL
MOISTURE CONTINUES TO ADVECT NORTHEASTWARD AWAY FROM THE
TROPICAL WAVE IMPACTING THE YUCATAN PENINUSLA AND ALONG WITH THE
DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 23N-
28N BETWEEN 74W TO BEYOND 81W AND INTO THE SE GULF OF MEXICO. TO
THE NORTH OF THIS AREA...A STATIONARY FRONT IS ANALYZED ALONG
32N-33N AND IS PROVIDING FOR ISOLATED SHOWERS AND TSTMS OFFSHORE
OF THE CAROLINAS N OF 31N BETWEEN 74W-81W. OVER THE REMAINDER OF
THE SW NORTH ATLC...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR
30N65W AND SUPPORTS A SURFACE TROUGH ANALYZED FROM 34N66W TO
28N69W. LOW-LEVEL CONVERGENCE IN THE VICINITY OF THE SURFACE
TROUGH ALONG WITH UPPER LEVEL LIFT PROVIDING BY THE UPPER LEVEL
LOW IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 23N-33N
BETWEEN 60W-72W. FINALLY...THE CENTRAL AND EASTERN CARIBBEAN ARE
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1026 MB
HIGH CENTERED NORTH OF THE DISCUSSION AREA NEAR 35N45W.

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

$$
HUFFMAN


This weather bulletin was brought to you by:
www.nashvilleweather.net