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Atlantic Tropical Weather Discussion (Text)

000
AXNT20 KNHC 201755
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON MAY 20 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 34W TO 07N33W MOVING 
W AT 10-15 KT. EXAMINING GLOBAL MODEL POTENTIAL VORTICITY 
ANALYSES AT THE 315K LEVEL...A MAXIMUM IS NOTED IN THE VICINITY 
OF THE WAVE AXIS. IN ADDITION...A MAXIMUM IN TOTAL PRECIPITABLE 
WATER IS OBSERVED IN IMAGERY FROM THE EQUATOR TO 07N BETWEEN 32W-
39W. ISOLATED MODERATE CONVECTION IS FROM 01N-06N BETWEEN 30W-
40W.

TROPICAL WAVE EXTENDS FROM 07N63W TO 14N60W MOVING W AT 10-15 
KT. THE WAVE COINCIDES WITH AN AMPLIFIED NORTHWARD MAXIMUM OF 
TOTAL PRECIPITABLE WATER THAT CONTINUES TO IMPACT THE WINDWARD 
ISLANDS AND AREAS TO THE EAST FROM 08N-17N BETWEEN 56W-62W. 
ISOLATED MODERATE CONVECTION IS FROM 09N-14N BETWEEN 57W-63W. 
THIS CONVECTION IS LIKELY ENHANCED BY DIFFLUENT FLOW ALOFT DUE 
TO MIDDLE TO UPPER LEVEL SOUTHWESTERIES LOCATED OVER THE SE 
CARIBBEAN.

...ITCZ/MONSOON TROUGH...                                     
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 08N13W TO 
06N15W TO 04N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS 
EXTENDS FROM 04N20W TO 02N34W TO THE EQUATOR NEAR 37W. WIDELY 
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF A 
LINE FROM THE PRIME MERIDIAN AND 04N TO 06N15W TO 06N19W. 
SCATTERED MODERATE CONVECTION IS FROM 01N-08N BETWEEN 20W-29W.

...DISCUSSION...

GULF OF MEXICO...                                               
MIDDLE TO UPPER LEVEL NORTHWESTERLY FLOW ALOFT IS NOTED ON WATER 
VAPOR IMAGERY ACROSS MUCH OF THE GULF W OF 85W THAT CONTINUES TO 
SUPPORT A SURFACE RIDGE REMAINING ANCHORED IN THE WESTERN ATLC. 
ACROSS THE EASTERN GULF AND FLORIDA PENINSULA HOWEVER...THE 
INFLUENCE OF THE SURFACE RIDGE IS LESSENED BY A WEAK MIDDLE TO 
UPPER LEVEL SHORTWAVE TROUGH WITH FOCUS CENTERED OVER NORTHERN 
FLORIDA NEAR 30N83W. THIS FEATURE IS RESULTING IN WIDELY 
SCATTERED SHOWERS AND TSTMS E OF 82W ACROSS THE FLORIDA STRAITS 
AND INLAND AREAS OF THE SOUTHERN FLORIDA PENINSULA. OTHERWISE... 
THE NEXT FEW DAYS WILL BE DOMINATED BY THE SURFACE RIDGING 
PROVIDING SE WINDS IN THE RANGE OF 10 TO 20 KT.

CARIBBEAN SEA...                                           
MIDDLE TO UPPER LEVEL NORTHWEST FLOW ALOFT IS NOTED ON WATER 
VAPOR IMAGERY W OF 72W ON THE NORTHEASTERN PERIPHERY OF AN 
ANTICYCLONIC CIRCULATION CENTERED OVER THE EASTERN PACIFIC 
REGION NEAR 14N93W. 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 ACROSS THE SW 
CARIBBEAN S OF 12N AS THE MONSOON TROUGH IS ANALYZED ALONG 09N 
ACROSS PANAMA AND COSTA RICA. EAST OF 72W...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 61W IMPACTING THE WINDWARD ISLANDS. 
OTHERWISE...EASTERLY TRADES ARE EXPECTED TO CONTINUE THROUGH 
MUCH OF THE WEEK WITH LITTLE CHANGE ON THE SYNOPTIC SCALE.

HISPANIOLA...                                           
CURRENTLY NORTHWESTERLY FLOW ALOFT IS OVER HISPANIOLA WITH WATER 
VAPOR IMAGERY INDICATING A MODERATELY DRY AIRMASS IN PLACE AND 
MOISTURE ASSOCIATED WITH THE INFLUENCE OF A SHORTWAVE TROUGH 
MOVING ACROSS THE FLORIDA PENINSULA REMAINING MOSTLY N OF 20N. 
THE OVERALL SYNOPTIC PATTERN REMAINS THE SAME AS THE PAST FEW 
DAYS WITH E-SE TRADES PREVAILING AND THE HIGHEST PRECIPITATION 
CHANCES OCCURING IN THE AFTERNOON THROUGH LATE EVENING HOURS 
WITH PEAK DAYTIME HEATING AND INSTABILITY. ISOLATED SHOWERS ARE 
BEGINNING TO INITIATE OVER INLAND AREAS OF THE DOMINICAN 
REPUBLIC AND A FEW ISOLATE SHOWERS ARE NOTED OVER THE ADJACENT 
COASTAL WATERS N OF 17N BETWEEN 69W-72W. AS PREVIOUSLY MENTIONED 
IN THE CARIBBEAN SEA SECTION...LITTLE CHANGE IS EXPECTED OVER 
THE NEXT FEW DAYS SYNOPTICALLY...RESULTING IN HIGHER PROBABILITY 
OF PRECIPITATION DURING THE AFTERNOON AND EVENING HOURS.

ATLANTIC OCEAN...                                                
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS LOCATED OVER 
NORTHERN FLORIDA AND CONTINUES TO MOVE E-NE INTO THE SW NORTH 
ATLC REGION BRINGING WITH IT INCREASED CLOUDINESS AND 
PRECIPITATION THIS AFTERNOON. CURRENTLY WIDELY SCATTERED SHOWERS 
AND TSTMS ARE OCCURRING W OF A LINE FROM THE CENTRAL BAHAMAS 
NEAR 23N75W TO THE SOUTH CAROLINA COAST NEAR 32N80W. THIS 
ACTIVITY IS OCCURRING ABOVE SURFACE RIDGING ANCHORED BY A 1028 
MB HIGH CENTERED NORTH OF BERMUDA NEAR 37N64W. FARTHER EAST...A 
NORTHWEST NORTH ATLC UPEPR LEVEL TROUGH IS CENTERED NORTH OF THE 
AREA NEAR 41N53W THAT LEADS TO BROAD UPPER LEVEL TROUGHING 
ACROSS THE CENTRAL ATLC BETWEEN 45W-70W AND SUPPORTS A COLD 
FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N51W. THE COLD 
FRONT EXTENDS SW TO 28N62W AND ALSO EXHIBITS A PRE-FRONTAL 
SURFACE TROUGH EXTENDING FROM THE COLD FRONT NEAR 29N55W TO 
24N64W. ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE 
OF THE COLD FRONT AND WITHIN 45 NM EITHER SIDE OF THE SURFACE 
TROUGH. IN ADDITION...TO THE EAST OF THE SURFACE TROUGH...A WEAK 
1019 MB LOW IS CENTERED NEAR 27N48W WITH ISOLATED SHOWERS 
OCCURRING WITHIN 180 NM OF THE NORTHERN SEMICIRCLES AND WITHIN 
60 NM EITHER SIDE OF A LINE FROM 23N44W TO 27N45W. THE REMAINDER 
OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE 
ANCHORED BY A 1034 MB HIGH CENTERED NORTH OF THE AZORES NEAR 
43N29W.

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

$$
HUFFMAN