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AXNT20 KNHC 271801
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED MAY 27 2015

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 1745 UTC.


...TROPICAL WAVES...

A TROPICAL WAVE IS ANALYZED JUST W OF THE ITCZ FROM THE EQUATOR TO 13N WITH AXIS ALONG 50W/51W...MOVING AT 13 KT. SSMI TPW IMAGERY SHOW THE WAVE CONTINUES TO BE EMBEDDED WITHIN ABUNDANT MOISTURE IN THE MIDDLE TO LOWER LEVELS. SATELLITE DERIVED WINDS AND MODEL GUIDANCE SHOW A DIFFLUENT ENVIRONMENT ALOFT THAT SUPPORT SCATTERED MODERATE CONVECTION WITHIN 180-240 NM W OF THE WAVE AXIS FROM 07N TO 10N. STRONG AT HIGH LEVELS OF THE ATMOSPHERE ARE PREVENTING THE CONVECTION FROM PERSISTING ONCE IT FORMS. THE WAVE IS FORECAST TO MOVE INLAND S AMERICA IN ABOUT 36-48 HRS.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS OFF THE AFRICAN COAST NEAR 07N13W...AND CONTINUES TO 05N20W. THE ITCZ BEGINS AT 05N20W... AND CONTINUES TO 05N30W AND TO JUST E OF THE TROPICAL WAVE ALONG 50W/51W. SCATTERED MODERATE CONVECTION IS WITHIN 60-120 NM S OF THE TROUGH BETWEEN 10W-20W. FOR CONVECTION ASSOCIATED WITH THE TROPICAL WAVE SEE THE SECTION ABOVE.


...DISCUSSION...

GULF OF MEXICO...

A SHARP UPPER TROUGH AXIS EXTENDS FROM WESTERN ALABAMA S TO 25N87W AND TO THE FAR NW CARIBBEAN SEA. AN ASSOCIATED UPPER LEVEL DISTURBANCE IS MOVING ACROSS SOUTHERN LOUISIANA AS VERY DEEP MOIST SOUTHERLY FLOW OF 15 KT AROUND THE SOUTHERN PERIPHERY OF A WESTERN ATLANTIC RIDGE THAT STRETCHES FROM THE WESTERN ATLANTIC SW TO THE NE GULF REMAINS IN PLACE. EARLIER DEEP CONVECTION OF SCATTERED MODERATE/ISOLATED STRONG TYPE INTENSITY THAT FIRED UP OVER EASTERN TEXAS EARLY THIS MORNING HAS PUSHED SEWD INTO THE FAR N CENTRAL WATERS S AND SW OF LOUISIANA. AS OF 15Z...IT IS ANALYZED AS A FAST MOVING SQUALL LINE THAT EXTENDS FROM S CENTRAL LOUISIANA SW TO 28N94W. THE CONVECTION EXTENDS WITHIN ABOUT 30 NM OF THIS LINE. BROAD UPPER RIDGING IS SLIDING EASTWARD BEHIND THE UPPER TROUGH. WATER VAPOR IMAGERY SHOWS MODERATE SUBSIDENCE WITH RATHER STABLE ATMOSPHERIC CONDITIONS S OF 27N AND W OF 90W. SCATTERED TO LOCALLY BROKEN LOW CLOUDS WITH ISOLATED SHOWERS MOVING QUICKLY WNW IN THE MOIST SE FLOW ARE SEEN S OF 26N E OF 88W...WHILE SCATTERED SHOWERS AND ISOLATED TSTMS ARE UNDERNEATH THE UPPER TROUGH AXIS FROM 23N-26N BETWEEN 88W-90W. THE TYPICAL NOCTURNAL TROUGH MOVED OFF THE YUCATAN PENINSULA THIS MORNING...AND IS OVER THE EASTERN PART OF THE SW GULF. IT HAS NO CONVECTION WITH IT AS IT IS UNDER THE DRY AND SUBSIDENT AIR ALOFT. HAZE APPEARS TO BE THINNING OUT OVER THE NW GULF. THE UPPER TROUGH WILL REACH THE EASTERN GULF THU...THEN WEAKEN ON FRI AS SURFACE RIDGING CHANGES LITTLE OVER THE NE AND CENTRAL GULF PORTIONS.

CARIBBEAN SEA...

BROAD UPPER TROUGHING EXTENDS FROM THE CENTRAL ATLANTIC SW TO THE SW CARIBBEAN. THE UPPER FLOW IS NW BEHIND THE TROUGH. MODERATE SUBSIDENCE ALOFT WITH STABLE ATMOSPHERIC CONDITIONS AND GENERALLY FAIR WEATHER CONDITIONS ARE SEEN OVER MUCH OF THE CARIBBEAN BASIN...WITH THE EXCEPTION OF THE FAR NW PORTION WHERE THE LOW-LEVEL ELY FLOW IS QUITE MOIST AND UNSTABLE AHEAD OF THE AFOREMENTIONED GULF OF MEXICO UPPER TROUGH. SCATTERED SHOWERS AND ISOLATED TSTMS ARE SEEN N OF 18N BETWEEN 79W-85W. A PATCH OF LOW-LEVEL MOISTURE WITH ISOLATED SHOWERS MOVING WESTWARD IS FROM 16N-19N BETWEEN SW HAITI TO JUST E OF JAMAICA. VERY SHALLOW MOISTURE OVER THE NE CARIBBEAN SUPPORTS ISOLATED SHOWERS N OF 15N E OF 68W. NWS DOPPLER RADAR FROM SAN JUAN AND SATELLITE IMAGERY ARE SHOWING SCATTERED SHOWERS AND TSTMS DEVELOPING OVER THE INTERIOR OF PUERTO RICO WITH DAYTIME HEATING...AND WITH THE APPROACH OF A WEAK LOW-LEVEL INSTABILITY BOUNDARY APPROACHING FROM THE N. A STRONG UPPER JET E OF THE UPPER TROUGH IS PRESENT ACROSS THE FAR SOUTHERN CARIBBEAN. IT IS ADVECTING THIN UPPER MOISTURE EASTWARD S OF 14N AND E OF NW COLOMBIA.

THE COMBINATION BETWEEN HIGH PRESSURE ACROSS THE ATLANTIC AND BROAD LOW PRESSURE OVER COLOMBIA AND THE SW CARIBBEAN IS RESULTING IN A TIGHT PRESSURE GRADIENT IN THE SW CARIBBEAN PRODUCING NE-E WINDS OF 20-25 KT FROM 11N-14N BETWEEN 72W-77W WITH SEAS THERE UP TO 9 FT. ELSEWHERE...TRADE WINDS OF 15-20 KT ARE PRESENT WITH SEAS LESS THAN 8 FT ARE PRESENT. OVERALL...NO SIGNIFICANT CHANGES ARE EXPECTED OVER THE NEXT COUPLE OF DAYS.


...HISPANIOLA...

STRONG SUBSIDENCE ALOFT IS BRINGING MOSTLY DEEP LAYER DRY AIR ACROSS JUST ABOUT THE ENTIRE ISLAND...EXCEPT OVER THE EXTREME SW PORTION WHERE SHALLOW LAYER MOISTURE...AND UPPER LEVEL TROUGHING IN THE VICINITY SUPPORTS PATCHES OF LOW-LEVEL MOISTURE WITH ISOLATED SHOWERS OVER THE SW PORTION...AND WSW FROM THERE TO JUST E OF JAMAICA. SCATTERED TO LOCALLY BROKEN LOW CLOUDS WITH ISOLATED SHOWERS AND TSTMS ARE JUST BEGINNING TO DEVELOP OVER THE MAINLY THE HIGHER TERRAIN AREAS. THIS ACTIVITY MAY REACH MORE OF THE SCATTERED LIMITS LATER IN THE AFTERNOON...AND AGAIN ON THU AS THE INFLUENCING SYNOPTIC PATTERN CHANGES LITTLE. PRECIPITABLE WATER GUIDANCE SUGGESTS THAT MOISTURE CONTENT INCREASES THU AND FRI FOR MUCH OF HISPANIOLA AND VICINITY WATERS.

ATLANTIC OCEAN...

A NEARLY STATIONARY MID/UPPER LEVEL LOW ANCHORED NEAR 26N61W CONTINUES TO SUPPORT A SURFACE TROUGH WITH AXIS EXTENDING FROM 32N62W TO 28N63W...AND TO 22N59W. SATELLITE IMAGERY DEPICTS NUMEROUS SHOWERS AND SCATTERED TSTMS FROM 24N-30N BETWEEN 51W- 58W. SCATTERED SHOWERS AND TSTMS ROTATING CYCLONICALLY ARE NOTED FROM 24N-30N BETWEEN 58W-63W. A TROPICAL WAVE IS W OF THE ITCZ AS DESCRIBED UNDER TROPICAL WAVES SECTION ABOVE. WATER VAPOR IMAGERY SHOWS MODERATE TO STRONG SUBSIDENCE PREVAILING W OF THE MID/UPPER LOW AND SURFACE KEEPING MOSTLY TRANQUIL WEATHER THERE...WITH THE EXCEPTION OF THE WATERS BETWEEN THE BAHAMA ISLAND CHAIN AND THE GREATER ANTILLES WHERE LOW-LEVEL MOISTURE LEFT OVER FROM A PREVIOUS INSTABILITY LINE IS ADVECTING WSW TOWARDS THOSE AREAS. THE SSMI TPW IMAGERY PICKS UP ON THIS LOW -LEVEL MOISTURE WHICH IS ATTENDANT BY WIDELY SCATTERED SHOWERS. ELSEWHERE SURFACE HIGH PRESSURE AND FAIR WEATHER PREVAILS. THE SURFACE TROUGH WILL CONTINUE TO DRIFT WESTWARD DURING THE NEXT 48 HOURS WITH POSSIBLE WEAK LOW PRESSURE ALONG IT. STRONG HIGH PRESSURE RIDGING IS OBSERVED E OF THE TROUGH ACROSS THE EASTERN PART OF THE DOMAIN.

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

$$ AGUIRRE

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