[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 090002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON APR 08 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
2300 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF SIERRA LEONE NEAR
08N13W TO 02N23W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 02N23W TO THE EQUATOR ALONG 30N TO THE COAST OF
BRAZIL NEAR 03S39W. SCATTERED MODERATE CONVECTION PERSISTS
WITHIN 210 NM OF THE MONSOON TROUGH AXIS BETWEEN 13W AND 17W AND
WITHIN 120 NM N OF THE ITCZ BETWEEN 30W AND 35W.

...DISCUSSION...

GULF OF MEXICO...
A MID LEVEL SHORT WAVE TROUGH ROTATING AROUND
THE BASE OF THE MAIN TROUGH CENTERED OVER THE GREAT BASIN
THROUGH TEXAS IS SUPPORTING A BROAD AREA OF SHOWERS OVER THE FAR
NW GULF OF MEXICO THIS AFTERNOON. WIDESPREAD MULTI-LEVEL CLOUD
COVER IS NOTED N OF 25N W OF 90W. COASTAL RADAR RETURNS HINT
THIS SHOWER ACTIVITY IS MAINLY FROM SW LOUISIANA TO OFF THE
NORTH COAST OF THE MEXICAN STATE OF TAMAULIPAS. ELSEWHERE
GENERALLY STABLE CONDITIONS CONTINUE UNDER DOMINANCE OF HIGH
PRES OVER THE GULF. A SURFACE RIDGE EXTENDS FROM THE WESTERN
ATLC ACROSS THE NORTHERN GULF TO THE TEXAS COAST. BUOY...SHIP
AND OSCAT DATA INDICATE MODERATE TO FRESH SE FLOW S OF THE RIDGE
OVER MUCH OF THE SOUTHERN GULF MAINLY S OF 25N...AND LIGHT TO
MODERATE FLOW OVER THE NORTHERN GULF WATERS. LOOKING
AHEAD...SOUTHERLY WINDS OVER THE NW GULF WILL INCREASE THROUGH
MIDWEEK...AHEAD OF A COLD FRONT THAT WILL REACH THE NW GULF BY
LATE WED. THE FRONT IS EXPECTED TO MOVE SE AND STALL FROM FORT
MYERS FLORIDA TO THE W CENTRAL GULF ON SAT.

CARIBBEAN SEA...
A 1025 MB HIGH PRES AREA CENTERED W OF BERMUDA
NEAR 33N70W CONTINUES TO BE THE MAIN INFLUENCE ON THE WEATHER
OVER THE CARIBBEAN...MAINTAINING GENERALLY MODERATE TO FRESH
TRADE WIND FLOW OVER MUCH OF THE EASTERN CARIBBEAN BASIN...AND
LIGHT TO MODERATE E TO SE WINDS OVER THE WESTERN CARIBBEAN. AN
ASCAT PASS FROM AROUND 17 UTC SHOWED NE TO E WINDS NEAR 25 KT
OFF THE COAST OF COLOMBIA. BOUNDARY LAYER TURBULENCE ASSOCIATED
WITH THE FRESH TRADES IS SUPPORTING A FEW DOWNSTREAM SHOWERS
OVER THE WATERS JUST W OF THE LEEWARD AND WINDWARD ISLANDS...AND
W OF HISPANIOLA. AFTERNOON THUNDERSTORMS OVER THE HIGHER TERRAIN
OF HISPANIOLA AND EASTERN CUBA HAVE STARTED TO DIMINISH. MID AND
UPPER LEVELS REMAIN DRY WITH WESTERLY ZONAL FLOW...MAINTAINING
STABLE AND GENERALLY CLOUD FREE AREAS ELSEWHERE ACROSS THE
CARIBBEAN. RIDGING WILL REMAIN IN EFFECT THROUGH THE REMAINDER
OF THE WEEK...WITH LITTLE CHANGE EXPECTED IN PREVAILING
CONDITIONS.

ATLANTIC OCEAN S OF 32N... DEEP LAYER RIDGING CONTINUES TO COVER
THE ATLC WATERS W OF 50W. A MID/UPPER RIDGE IS BUILDING E AND
COMING INTO PHASE WITH A 1025 MB SURFACE HIGH CENTERED W OF
BERMUDA NEAR 33N70W. MODERATE E TRADES ARE NOTED IN BUOY AND
SCATTEROMETER DATA W OF 50W N OF 22N...WITH MODERATE TO FRESH
TRADES NOTED S OF 22N. HIGH MOISTURE VALUES OVER THE GULF STREAM
ARE CONTRIBUTING TO A FEW LOW TOPPED SHOWERS OFF THE COAST OF E
CENTRAL FLORIDA...ALTHOUGH THIS IS NOT MAKING IT INLAND. JUDGING
BY VISIBLE SATELLITE IMAGERY FROM THIS AFTERNOON...ADDITIONAL
SHOWERS MAY BE ACTIVE DUE TO TRADE WIND CONVERGENCE FROM 20N TO
25N BETWEEN 50W AND 70W. THE RIDGING IS FOLLOWING BEHIND A LOW
AMPLITUDE SHORT WAVE TROUGH OVER THE N CENTRAL ATLC...WHICH HAD
BEEN PROVIDING SUPPORT TO A COLD FRONT ANALYZED FROM 32N49W TO
25N57W THEN WESTWARD AS A STATIONARY FRONT TO EASTERN CUBA. THE
SUPPORTING MID/UPPER TROUGH ASSOCIATED WITH THE FRONT IS LIFTING
NE...WHICH WILL ALLOW THE FRONT TO GRADUALLY BECOME DIFFUSE
THROUGH THE NEXT 24 TO 36 HOURS. SCATTEROMETER DATA INDICATE
FRESH NW TO N FLOW BEHIND THE FRONT N OF 30N W OF THE FRONT TO
58W. NO SIGNIFICANT WEATHER APPEARS ACTIVE ALONG THE FRONT AT
THIS TIME. FARTHER EAST...BROAD RIDGING DOMINATES THE EASTERN N
ATLC S OF 32N...WITH A 1023 MB SURFACE HIGH CENTERED NEAR
30N35W. THIS HIGH IS EXPECTED TO PUSH RAPIDLY EAST THROUGH TUE
AHEAD OF THE APPROACHING WEAK SHORT WAVE...AND FOLLOWING ANOTHER
WEAK SHORT WAVE SHOWING UP IN WATER VAPOR IMAGERY AND SATELLITE
DERIVED WINDS FROM 25N23N TO 15N40W. ASIDE FROM UPPER CIRRUS
ASSOCIATED WITH THIS SHORT WAVE...AND WIDELY DISPERSED FIELDS OF
STRATO CUMULUS CLOUDS...DEEP LAYER MOISTURE REMAINS LIMITED AND
NO APPRECIABLE WEATHER IS NOTED E OF 35W. MODERATE TO FRESH
TRADE WIND PERSIST S OF 20N TO THE S OF THE RIDGE AXIS.

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

$$
CHRISTENSEN

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