000
AXNT20 KNHC 182347
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT MAY 18 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 
2315 UTC.

...TROPICAL WAVES...                                     
TROPICAL WAVE EXTENDS FROM 10N53W TO 5N56W MOVING W AT 15 KT. 
THE WAVE REMAINS LOW-AMPLITUDE AND HAS BROKEN AWAY FROM THE 
INFLUENCE OF THE ITCZ AXIS WHICH IS LOCATED TO THE SE. THE WAVE 
COINCIDES WITH A MAXIMUM IN TOTAL PRECIPITABLE WATER IMAGERY 
THAT EXTENDS NORTHWARD TO NEAR 13N. ISOLATED MODERATE CONVECTION 
IS BOTH EAST AND WEST OF THE WAVE FROM 5N-11N BETWEEN 47W-
55W...AND FROM 7N-11N BETWEEN 55W-59W. THIS CONVECTION IS LIKELY 
ENHANCED DUE TO UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE 
WESTERN PERIPHERY OF AN UPPER LEVEL RIDGE OVER THE TROPICAL ATLC.

...ITCZ/MONSOON TROUGH...                                     
THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA NEAR 10N13W 
TO 5N18W. THE ITCZ BEGINS AT 5N18W AND CONTINUES ALONG 3N28W 
1N36W EQ46W 1S49W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION 
IS FROM 3N-5N BETWEEN 18W020W...AND FROM 2N-5N BETWEEN 27W-33W. 

...DISCUSSION...

GULF OF MEXICO...                                            
FAIR WEATHER CONTINUES TO BE PRESENT THROUGHOUT THE GULF OF 
MEXICO THIS EVENING. SURFACE RIDGING EXTENDS FROM THE WEST ATLC 
WITH AXIS FROM THE NE GULF TO SW GULF. THIS PATTERN SUPPORTS 
EAST TO SOUTHEAST WINDS RANGING FROM 5-10 KT IN THE EASTERN GULF 
TO 15-20 KT IN THE WESTERN GULF ESPECIALLY NEAR THE COAST OF 
TEXAS. THE RIDGE IS SUPPORTED ALOFT BY AN UPPER LEVEL RIDGE 
ALONG 93W. WATER VAPOR IMAGERY INDICATES DRY AIR COVERS MUCH OF 
THE BASIN EXCEPT FOR THE NW CORNER WHERE HIGH CLOUDS ARE ALSO 
PRESENT. VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW AN AREA OF 
SMOKE ACROSS THE SW GULF DUE TO FIRES OVER SOUTHERN MEXICO. A 
FEW CLUSTERS OF THUNDERSTORMS HAVE ALSO POPPED UP DOWN THE 
FLORIDA PENINSULA MOSTLY IN SOUTH FLORIDA AND THE NE CORNER OF 
THE STATE. LITTLE CHANGE IS EXPECTED OVER THE NEXT COUPLE OF 
DAYS. 

CARIBBEAN SEA...                                              
DRY AND STABLE AIR COVERS THE MAJORITY OF THE CARIBBEAN IN 
WESTERLY FLOW ALOFT. THE DRY AIR IS HELPING MAINTAIN GENERALLY 
FAIR WEATHER ACROSS THE BASIN. HOWEVER...AFTERNOON SHOWERS AND 
THUNDERSTORMS HAVE POPPED UP ACROSS MANY OF THE NORTHERN 
CARIBBEAN ISLANDS INCLUDING CUBA...JAMAICA...AND HISPANIOLA. A 
FEW ISOLATED SHOWERS ARE ALSO MOVING THROUGH THE NW CORNER OF 
THE BASIN INTO THE YUCATAN CHANNEL. SCATTERED 
SHOWERS/THUNDERSTORMS ARE ALSO IN THE FAR SW CORNER AND OVER 
COSTA RICA AND PANAMA ASSOCIATED WITH THE MONSOON TROUGH THAT 
EXTENDS FROM THE E PACIFIC THROUGH BOTH CONTINUE AND INTO 
COLOMBIA. TRADEWIND FLOW OF 15-20 KT DOMINATES THROUGHOUT. 
LITTLE CHANGE IS EXPECTED EXCEPT FOR AN INCREASE IN MOISTURE 
ACROSS THE WINDWARD ISLANDS AS A TROPICAL WAVE APPROACHED FROM 
THE EAST. 

HISPANIOLA...                                           
CURRENTLY AFTERNOON SHOWERS AND THUNDERSTORMS ARE BEGINNING TO 
DIE DOWN AFTER PEAKING AROUND 2100 UTC. SCATTERED 
SHOWERS/THUNDERSTORMS ARE STILL PRESENT THROUGHOUT THE ISLANDS 
MAINLY CENTERED IN THE CENTRAL PORTIONS. THIS ACTIVITY WILL 
LIKELY CONTINUE TO DIE DOWN OVER THE NEXT COUPLE OF HOURS. MODEL 
GUIDANCE INDICATES A SIMILAR PATTERN WILL PERSIST OVER THE NEXT 
COUPLE OF DAYS WITH THE MOST LIKELY PRECIPITATION TO BE DURING 
THE AFTERNOON AND EARLY EVENING HOURS ACROSS THE ISLAND WHEN 
PEAK DAYTIME HEATING AND INSTABILITY OCCUR. ANY AREAS THAT 
RECEIVE MEASURABLE AMOUNTS OF RAINFALL WILL LIKELY BE PRONE TO 
LOCALIZED FLOODING.

ATLANTIC OCEAN...                                            
UPPER LEVEL RIDGING ACROSS THE GULF OF MEXICO CONTINUES INTO THE 
WEST ATLC WHERE SURFACE RIDGING IS PRESENT AROUND A 1023 MB HIGH 
NEAR 30N70W. TO THE EAST...A SHORTWAVE UPPER TROUGH EXTENDS FROM 
33N58W TO 27N68W SUPPORTING A STATIONARY FRONTAL BOUNDARY ALONG 
32N56W 22N67W. ISOLATED SHOWERS ARE WITHIN 30 NM EITHER SIDE OF 
THE AXIS. A WEAK SURFACE TROUGH IS TO THE EAST ALONG 30N52W 
27N47W WITH NO NOTABLE PRECIPITATION. THE REMAINDER OF THE 
CENTRAL AND EASTERN ATLC IS DOMINATED BY BROAD SURFACE RIDGING 
AROUND A 1033 MB HIGH NEAR 42N30W. ALOFT...BROAD UPPER RIDGING 
COVERS THE TROPICAL ATLC WITH AN UPPER LEVEL LOW TO THE NORTH 
NEAR 31N39W. 

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

$$
WALTON