000
AXNT20 KNHC 190005
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT FEB 18 2012

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 
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF 
SIERRA LEONE NEAR 8N13W TO 4N18W. THE ITCZ CONTINUES FROM 4N18W 
TO BRAZIL NEAR 1S47W. SCATTERED MODERATE CONVECTION IS WITHIN 
120 NM OF THE ITCZ BETWEEN 18W AND 32W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...A 1006 MB LOW IS LOCATED OFF OF THE COAST NEAR 
THE BORDER OF LOUISIANA AND TEXAS NEAR 29N94W. A COLD FRONT 
EXTENDS SOUTH-SOUTHWESTWARD FROM THE LOW TO THE MEXICAN COAST 
NEAR 21N97W.  A STATIONARY FRONTAL BOUNDARY ALSO EXTENDS 
EASTWARD FROM THE LOW TO AN 1004 MB LOW OVER THE MISSISSIPPI 
GULF COAST.  FROM THAT LOW...A WARM FRONT EXTENDS EASTWARD OVER 
THE FLORIDA PANHANDLE TO A THIRD LOW OF 1012 MB JUST EAST OF 
THE FLORIDA-GEORGIA BORDER IN THE ATLANTIC NEAR 31N80W. 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 45 NM 
OF THE STATIONARY AND WARM FRONTS. THE LIGHTNING DETECTION 
SYSTEM SHOWS SUBSTANTIAL AMOUNTS OF LIGHTNING ALONG THE 
STATIONARY AND WARM FRONTS BETWEEN CENTRAL LOUISIANA TO THE 
FLORIDA PANHANDLE.  15-25 KT SOUTHWESTERLY WINDS ARE S OF THE 
STATIONARY FRONT OVER THE CENTRAL GULF OF MEXICO. 20 KT 
NORTHWESTERLY WINDS ARE N OF THE COLD FRONT. IN THE UPPER 
LEVELS...SW FLOW LINGERS OVER THE GULF WITH SIGNIFICANT UPPER 
LEVEL MOISTURE.  EXPECT OVER THE NEXT 24 HOURS FOR A MERGER OF 
THE LOWS TO MOVE NE TO GEORGIA-SOUTH CAROLINA. A COLD FRONT WILL 
EXTEND SW FROM THE LOW TO THE BAY OF CAMPECHE WITH CONVECTION.  
EXPECT SOME COLD AIR ADVECTION OVER THE N AND CENTRAL GULF N OF 
THE FRONT.  NO GALES ARE ANTICIPATED.   

CARIBBEAN SEA...
10-2 KT EASTERLY TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH 
STRONGEST WINDS ALONG THE COAST OF N COLOMBIA AND WEAKEST WINDS 
OVER THE W CARIBBEAN W OF 80W. SCATTERED SHOWERS DEVELOPED THIS 
AFTERNOON OVER PUERTO RICO AND HISPANIOLA.  MOSTLY FAIR WEATHER 
DOMINATES ELSEWHERE. IN THE UPPER LEVELS...AN UPPER LEVEL HIGH 
IS CENTERED OVER NICARAGUA. STRONG SUBSIDENCE COVERS THE ENTIRE 
CARIBBEAN AND CENTRAL AMERICA. EXPECT PREFRONTAL RAIN AND 
SHOWERS OVER THE YUCATAN PENINSULA AND THE NW CARIBBEAN WITHIN 
THE NEXT 24 HOURS. EXPECT LITTLE CHANGE ELSEWHERE.  NO GALES ARE 
ANTICIPATED.  

ATLANTIC OCEAN...
A FRONTAL BOUNDARY EXTENDS FROM A LOW JUST EAST OF THE 
FLORIDA-GEORGIA BORDER NEAR 31N80W EASTWARD TO 31N63W...WITH THE 
WESTERN THIRD BEING A WARM FRONT...THE MIDDLE A STATIONARY 
FRONT...AND THE EASTERN THIRD A COLD FRONT. SCATTERED SHOWERS 
ARE WITHIN 30 NM OF THE FRONT. A SURFACE TROUGH IS OVER THE 
CENTRAL ATLANTIC FROM 31N44W TO 18N48W TO 12N47W. SCATTERED 
SHOWERS AND ISOLATED MODERATE CONVECTION ARE OCCURRING WITHIN 
180 NM EAST OF THE TROUGH NORTH OF 25N.  A 1030 MB HIGH IS OVER 
THE E ATLANTIC NEAR THE AZORES AT 40N22W. A SURFACE RIDGE AXIS 
EXTENDS SW FROM THE HIGH TO 18N40W. IN THE UPPER LEVELS...AN 
UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLANTIC N OF 10N BETWEEN 
40W-55W PRODUCING WIDELY SCATTERED MODERATE CONVECTION IS N OF 
20N BETWEEN 40W-45W IN ASSOCIATION WITH THE SURFACE TROUGH. 
EXPECT OVER THE NEXT 24 HOURS FOR RAIN AND SHOWERS TO BE OVER 
THE W ATLANTIC N OF 27N AND W OF 62W. ALSO EXPECT ADDITIONAL 
CONVECTION OVER THE CENTRAL ATLANTIC DUE TO THE UPPER LEVEL 
TROUGH.  NO GALES ARE ANTICIPATED.    

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

$$
LANDSEA/FORMOSA