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Atlantic Tropical Weather Discussion (Text)

000
AXNT20 KNHC 211754
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE MAY 21 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 THE EQUATOR NEAR 40W TO 05N39W MOVING 
W AT 10 KT. EXAMINING GLOBAL MODEL POTENTIAL VORTICITY ANALYSES 
AT THE 315K LEVEL...A MAXIMUM IS NOTED IN THE VICINITY OF THE 
WAVE AXIS BETWEEN 37W-42W. IN ADDITION...A MAXIMUM IN TOTAL 
PRECIPITABLE WATER IS OBSERVED IN IMAGERY FROM THE EQUATOR TO 
06N BETWEEN 36W-43W. A WEAK 1012 MB SURFACE LOW IS ANALYZED WEST 
OF THE WAVE NEAR 04N37W. AT THIS TIME ENERGY ASSOCIATED WITH THE 
WAVE AND THE WEAK LOW MAY BE CONSOLIDATING AND RESULT IN A RE-
POSITIONING OR ADJUSTMENT OF THE WAVE AXIS AT 21/1800 UTC IF 
NECESSARY. ISOLATED MODERATE CONVECTION IS OCCURRING IN THE 
VICINITY OF THE WAVE AND LOW CENTER FROM 01N-05N BETWEEN 36W-40W.

TROPICAL WAVE EXTENDS FROM 09N68W TO 16N66W MOVING W AT 10-15 
KT. THE WAVE COINCIDES WITH A BROAD AREA OF MAXIMIZED TOTAL 
PRECIPITABLE WATER THAT CONTINUES TO PRODUCE ISOLATED SHOWERS 
OVER THE NE CARIBBEAN N OF 15N E OF 68W...INCLUDING PUERTO RICO 
AND THE LEEWARD ISLANDS. THIS CONVECTION IS LIKELY ENHANCED BY 
WEAK DIFFLUENT FLOW ALOFT DUE TO UPPER LEVEL WEST-SOUTHWESTERIES 
OVER THE FAR EASTERN CARIBBEAN.

...ITCZ/MONSOON TROUGH...                                     
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO 
08N16W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
08N16W TO 04N20W TO 03N26W. WIDELY SCATTERED MODERATE CONVECTION 
IS FROM 03N-06N BETWEEN 09W-18W...AND FROM 03N-06N BETWEEN 21W-
25W...AND WITHIN 120 NM EITHER SIDE OF A LINE FROM THE EQUATOR 
NEAR 28W TO 04N30W TO 06N34W.

...DISCUSSION...

GULF OF MEXICO...                                               
RELATIVELY DRY AIR WITHIN MIDDLE TO UPPER LEVEL NORTHWESTERLY 
FLOW ALOFT IS NOTED ON WATER VAPOR IMAGERY ACROSS MUCH OF THE 
GULF THIS AFTERNON. THIS PATTERN CONTINUES TO SUPPORT SURFACE 
RIDGING THAT REMAINS ANCHORED IN THE SW NORTH ATLC WHICH RESULTS 
IN PERSISTENT E-SE WINDS IN THE RANGE OF 10 TO 20 KT ACROSS THE 
BASIN. LOOKING AHEAD...OVERALL LITTLE CHANGE IS EXPECTED THROUGH 
LATE THURSDAY WHEN A WEAK FRONTAL BOUNDARY WILL SKIRT THE SE 
CONUS AND PORTIONS OF THE COASTAL NE GULF WATERS. LASTLY...OF 
NOTE...VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW A LARGE 
DISPERSED AREA OF SMOKE OVER THE WESTERN GULF W OF A LINE FROM 
GALVESTON TEXAS TO THE NE CORNER OF THE YUCATAN PENINSULA NEAR 
21N90W. THE SMOKE AND HAZY CONDITIONS ARE LARGELY DUE TO 
NUMEROUS AGRICULTURAL AND WILD FIRES OCCURRING OVER PORTIONS OF 
SOUTHERN MEXICO AND NORTHERN CENTRAL AMERICA.

CARIBBEAN SEA...                                           
MIDDLE TO UPPER LEVEL NORTHWEST FLOW ALOFT IS NOTED ON WATER 
VAPOR IMAGERY W OF 72W ON THE EASTERN PERIPHERY OF AN 
ANTICYCLONIC CIRCULATION CENTERED OVER THE EASTERN PACIFIC 
REGION NEAR 13N91W. VISIBLE SATELLITE IMAGERY INDICATES MOSTLY 
CLEAR SKIES UNDER THIS UPPER LEVEL REGIME WITH E-SE TRADE WINDS 
PERSISTING IN THE RANGE OF 10 TO 20 KT WITH POTENTIALLY HIGHER 
WIND SPEEDS IN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. THE 
ONLY EXCEPTION IS SCATTERED SHOWERS AND TSTMS ARE OCCURRING 
ACROSS THE SW CARIBBEAN S OF 13N AS THE MONSOON TROUGH IS 
ANALYZED ALONG 10N NORTH OF PANAMA AND ACROSS CENTRAL COSTA 
RICA. EAST OF 72W...WEST-SOUTHWESTERLY MIDDLE TO UPPER LEVEL 
WINDS DOMINATE AND CONTINUE TO PROVIDE AN OVERALL DIFFLUENT 
ENVIRONMENT THAT SUPPORTS THE CONVECTION ASSOCIATED WITH THE 
TROPICAL WAVE ALONG 68W IMPACTING THE EASTERN CARIBBEAN. 
OTHERWISE...EASTERLY TRADES ARE EXPECTED TO CONTINUE THROUGH 
MUCH OF THE WEEK WITH LITTLE CHANGE ON THE SYNOPTIC SCALE.

HISPANIOLA...                                           
CURRENTLY WEST-NORTHWESTERLY FLOW ALOFT IS OVER HISPANIOLA WITH 
WATER VAPOR IMAGERY INDICATING MORE MIDDLE TO UPPER LEVEL 
MOISTURE THAN IN THE LAST FEW PREVIOUS DAYS. THIS MOISTURE STEMS 
FROM A SHORTWAVE TROUGH CENTERED OVER NORTHERN FLORIDA THAT IS 
PROVIDING HISPANIOLA AND THE SURROUNDING REGION WITH MORE 
OVERALL MOISTURE TO WORK WITH TODAY. WHILE THE OVERALL SYNOPTIC 
PATTERN REMAINS THE SAME AS THE PAST FEW DAYS WITH E-SE TRADES 
PREVAILING...THE HIGHEST PRECIPITATION CHANCES ARE EXPECTED TO 
OCCUR DURING THE AFTERNOON THROUGH LATE EVENING HOURS WITH PEAK 
DAYTIME HEATING AND INSTABILITY. WIDELY SCATTERED SHOWERS ARE 
EXPECTED TO INITIATE OVER INLAND AREAS THIS AFTERNOON. AS 
PREVIOUSLY MENTIONED IN THE CARIBBEAN SEA SECTION...LITTLE 
CHANGE IS EXPECTED OVER THE NEXT FEW DAYS SYNOPTICALLY... 
HOWEVER...A TROPICAL WAVE WILL PASS TO THE SOUTH OVER THE 
SOUTHERN HALF OF THE CARIBBEAN RESULTING IN INCREASED LOW-LEVEL 
MOISTURE AND HIGHER PROBABILITY OF PRECIPITATION DURING THE 
AFTERNOON AND EVENING HOURS.

ATLANTIC OCEAN...                                                
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS LOCATED OVER 
NORTHERN FLORIDA CENTERED NEAR 29N82W AND CONTINUES TO BE SLOW 
TO MOVE INTO THE SW NORTH ATLC REGION BRINGING WITH IT INCREASED 
CLOUDINESS AND PRECIPITATION THIS AFTERNOON. CURRENTLY WIDELY 
SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 22N BETWEEN 73W-
81W...INCLUDING PORTIONS OF THE FLORIDA PENINSULA. THIS ACTIVITY 
IS OCCURRING ON THE WESTERN PERIPHERY OF A SURFACE RIDGE 
ANCHORED BY A 1025 MB HIGH CENTERED EAST OF BERMUDA NEAR 32N59W. 
FARTHER EAST...A NORTHWEST NORTH ATLC UPPER LEVEL TROUGH IS 
CENTERED NORTH OF THE AREA NEAR 45N49W THAT LEADS TO BROAD UPPER 
LEVEL TROUGHING ACROSS THE CENTRAL ATLC BETWEEN 38W-60W AND 
SUPPORTS A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 
32N45W. THE COLD FRONT EXTENDS SW TO 27N54W TO 27N61W AND ALSO 
EXHIBITS A PRE-FRONTAL SURFACE TROUGH EXTENDING FROM THE COLD 
FRONT NEAR 31N46W TO 24N49W. ISOLATED SHOWERS ARE OCCURRING 
WITHIN 90 NM EITHER SIDE OF THE COLD FRONT AND WITHIN 45 NM 
EITHER SIDE OF THE SURFACE TROUGH. THE REMAINDER OF THE EASTERN 
ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 
1035 MB HIGH CENTERED NORTH OF THE AZORES NEAR 48N27W.

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

$$
HUFFMAN