114 
AXNT20 KNHC 181753
TWDAT 

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

...TROPICAL WAVES...                                     
TROPICAL WAVE EXTENDS FROM 05N56W TO 11N52W 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 GLOBAL MODEL INDICATED AREA OF MAXIMUM 
POTENTIAL VORTICITY AT 315K WHICH HAS BEEN TRACKING WESTWARD 
OVER THE PAST FEW DAYS. TOTAL PRECIPITATABLE WATER AND SATELLITE 
IMAGERY ALSO INDICATE A MAXIMUM IN LOW-LEVEL MOISTURE 
CONVERGENCE AND CLOUDINESS IN THE VICINITY OF THE WAVE AXIS. 
ISOLATED MODERATE CONVECTION IS FROM 06N-11N BETWEEN 46W-60W. 
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 AFRICAN COAST NEAR 10N14W TO 
05N22W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
05N22W TO THE EQUATOR NEAR 4947W. SCATTERED MODERATE CONVECTION 
IS FROM 01N-03N BETWEEN THE PRIME MERIDIAN AND 02W. WIDELY 
SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 07N 
BETWEEN 08W-19W...AND FROM 01N-05N BETWEEN 26W-41W.

...DISCUSSION...

GULF OF MEXICO...                                         
VISIBLE SATELLITE IMAGERY SHOWS THE GULF BASIN REMAINS UNDER 
FAIRLY TRANQUIL CONDITIONS THIS AFTERNOON. WATER VAPOR IMAGERY 
INDICATES UPPER LEVEL WEST-NORTHWESTERLY FLOW WITH MID-LEVEL 
RIDGING PROVIDING FOR OVERALL STABLE CONDITIONS. AT THE 
SURFACE...A RIDGE AXIS EXTENDS FROM THE SW NORTH ATLC REGION 
NEAR 31N73W TO 22N98W AND IS PROVIDING SE WINDS GENERALLY IN THE 
RANGE OF 5 TO 10 KT EAST OF 90W AND 10 TO 20 KT WEST OF 90W. THE 
RIDGING IS EXPECTED TO REMAIN NEARLY STATIONARY THROUGH THE 
REMAINDER OF THE WEEKEND INTO THE MIDDLE OF NEXT WEEK WITH 
LITTLE CHANGE REGARDING WIND SPEEDS AND DIRECTION AS NOTED 
ABOVE. FINALLY...OF NOTE...VISIBLE SATELLITE IMAGERY INDICATES 
MODERATELY DENSE SMOKE MOVING NORTH-NORTHWESTWARD OFF THE 
SOUTHERN MEXICO COAST THAT COVERS A PORTION OF THE SW GULF S OF 
23N BETWEEN 91W-97W. THE SMOKE IS DUE TO SEVERAL AGRICULTURAL 
FIRES ACROSS SOUTHERN MEXICO AND NORTHERN CENTRAL AMERICA.

CARIBBEAN SEA...                                              
DRY AND STABLE WEST-NORTHWESTERLY MIDDLE TO UPPER LEVEL FLOW IS 
NOTED ON WATER VAPOR IMAGERY ACROSS THE NW CARIBBEAN WITH UPPER 
LEVEL WINDS SHIFTING SLIGHTLY MORE WEST-SOUTHWEST OVER THE 
CENTRAL AND EASTERN CARIBBEAN E OF 78W. MODERATELY DRY AIR 
PREVAILS ALOFT E OF 78W...HOWEVER VISIBLE SATELLITE IMAGERY 
SHOWS A FEW PASSING CIRRUS CLOUDS OVER THIS AREA. SCATTERED 
SHOWERS AND TSTMS ARE OCCURRING S OF 12N BETWEEN 77W-84W AND 
LIKELY WILL PERSIST DUE TO LOW-LEVEL MOISTURE CONVERGENCE AND 
THE CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS ACROSS PANAMA AND 
SOUTHERN COSTA RICA. OTHERWISE...TRADES CONTINUE IN THE RANGE OF 
10 TO 20 KT WITH SLIGHTLY HIGHER WIND SPEEDS EXPECTED S OF 14N 
BETWEEN 69W-76W IN THE VICINITY OF THE COLOMBIA AND NW VENEZUELA 
COAST. A FEW AREAS OF ISOLATED SHOWERS ARE OCCURRING IN THE NW 
CARIBBEAN N OF 18N BETWEEN 78W-86W...AND REMAIN PRIMARILY WITHIN 
THE ADJACENT COASTAL WATERS SOUTH OF CUBA AND EAST OF THE 
YUCATAN PENINSULA. EASTERLY TRADES ARE EXPECTED TO PERSIST 
THROUGH THE WEEK AHEAD AS A SURFACE RIDGE REMAINS ANCHORED 
ACROSS THE SW NORTH ATLC TO THE NORTH OF THE BASIN.

HISPANIOLA...                                           
CURRENTLY WESTERLY WINDS ALOFT ARE CONTINUING TO PROVIDE AN 
OVERALL STABLE ENVIRONMENT OVER THE ISLAND THIS AFTERNOON.  
WHILE THE TRADE WIND FLOW REGIME WILL REMAIN PERSISTENT THROUGH 
THE REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK...AND GIVEN A 
MODERATELY DRY UPPER LEVEL FLOW PATTERN IN PLACE...THE MOST 
LIKELY PRECIPITATION WILL CONTINUE TO BE ISOLATED SHOWERS AND 
TSTMS DURING THE AFTERNOON AND EARLY EVENING HOURS ACROSS THE 
ISLAND WHEN PEAK DAYTIME HEATING AND INSTABILITY OCCUR. ANY 
AREAS THAT RECEIVE MEASUREABLE AMOUNTS OF RAINFALL WILL LIKELY 
BE PRONE TO LOCALIZED FLOODING.

ATLANTIC OCEAN...                                            
WEST-NORTHWESTERLY FLOW ALOFT IS NOTED ON WATER VAPOR IMAGERY 
OVER MUCH OF THE SW NORTH ATLC. THIS RATHER STABLE REGIME ALOFT 
IS SUPPORTIVE OF A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH 
CENTERED NEAR 31N73W AND IS PROVIDING FOR OVERALL FAIR 
CONDITIONS. ON THE SOUTHERN AND WESTERN PERIPHERY OF THE RIDGE 
HOWEVER...A FEW ISOLATED SHOWERS AND TSTMS ARE POSSIBLE AS NOTED 
ON SATELLITE IMAGERY AND MOSAIC DOPPLER RADAR IMAGERY OFF THE 
COAST OF THE FLORIDA PENINSULA. FARTHER EAST...A WEAK MID-LEVEL 
SHORTWAVE TROUGH AXIS EXTENDS FROM 33N60W TO 29N69W AND IS 
SUPPORTING A STATIONARY ANALYZED FROM 32N56W TO 21N67W. ISOLATED 
SHOWERS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF THE BOUNDARY 
N OF 23N. IN ADDITION ACROSS THE CENTRAL ATLC...A WEAK SURFACE 
TROUGH IS ANALYZED FROM 26N44W TO 30N52W. OTHERWISE...THE 
REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE 
OF A SURFACE RIDGE ANCHORED BY A 1033 MB HIGH CENTERED N-NW OF 
THE AZORES NEAR 41N30W.

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

$$
HUFFMAN