000 AXNT20 KNHC 281121 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST SAT FEB 28 2009 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N5W 2N11W CROSSING THE EQUATOR NEAR 17W EXTENDING TO 2S31W INTO NE BRAZIL NEAR 3S47W. SCATTERED MODERATE CONVECTION IS FROM 1N-3N BETWEEN 8W-13W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF 2N BETWEEN 15W-24W. ...DISCUSSION... GULF OF MEXICO... GENERALLY FAIR WEATHER IS PRESENT ACROSS MUCH OF THE GULF REGION...WHERE NORTHWESTERLY FLOW ALOFT IS SUPPORTING ATMOSPHERIC SUBSIDENCE AND STABLE ATMOSPHERIC CONDITIONS. THE SUBSIDENCE IS ALSO BEING SUPPORTED BY A SURFACE RIDGE OVER THE GULF. DEEP LAYER DRY AIR IS ALSO PRESENT ACROSS MUCH OF THE GULF REGION. HOWEVER...UPPER LEVEL MOISTURE IS STREAMING SOUTHEASTWARD ACROSS PORTIONS OF THE N AND CENTRAL GULF. ACROSS THE CENTRAL AND SOUTHERN PLAINS OF THE CONUS...A DEEP LAYER TROUGH IS PRESENT. THIS DEEP LAYER TROUGH IS ASSOCIATED WITH A SURFACE FRONT OVER S TEXAS. THE SURFACE FRONT IS EXPECTED TO MOVE SOUTHWARD OFF THE TEXAS COAST THIS MORNING AND IS EXPECTED TO HAVE MOVED E OF THE GULF SUNDAY NIGHT. IN THE WAKE OF THE COLD FRONT...INCREASED NORTHERLY WINDS ARE FORECAST TO OCCUR OVER THE GULF...WITH A GALE WARNING IN EFFECT FOR PORTIONS OF THE SW GULF FOR TONIGHT AND SUNDAY. ALSO...RELATIVELY COOLER AND DRIER CONDITIONS ARE PRESENT TO THE N OF THE FRONT. CARIBBEAN SEA... GENERALLY FAIR WEATHER CONDITIONS ARE OCCURRING ACROSS MUCH OF THE CARIBBEAN REGION...WHERE SUBSIDENCE IS BEING SUPPORTED BY CONFLUENCE IN WESTERLY FLOW ALOFT. PATCHES OF LOW LEVEL MOISTURE CONTINUE TO BE ADVECTED WESTWARD ACROSS THE CARIBBEAN...WITH SCATTERED SHOWERS EMBEDDED WITHIN THESE PATCHES OF LOW LEVEL MOISTURE. THE GREATEST CONCENTRATION OF THESE SHOWERS IS FROM 12N-16N E OF 65W. ALSO...INCREASED UPPER LEVEL MOISTURE IS STREAMING NORTHEASTWARD ACROSS PORTIONS OF THE E CARIBBEAN. ATLANTIC OCEAN... A DEEP LAYER TROUGH OVER THE CENTRAL ATLC IS ASSOCIATED WITH A SURFACE STATIONARY FRONT OVER THE CENTRAL ATLC THAT EXTENDS FROM 24N65W TO 28N57W TO 31N46W AND A SURFACE COLD FRONT ALSO OVER THE CENTRAL ATLC THAT EXTENDS FROM 31N46W TO 32N41W TO NE OF THE DISCUSSION AREA. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 120 NM EITHER SIDE OF THESE FRONTS. THIS ACTIVITY IS BEING ENHANCED BY ATMOSPHERIC LIFT ASSOCIATED WITH UPPER LEVEL DIVERGENCE IN THE SW QUADRANT OF A 110-120 KT UPPER LEVEL JET MAXIMUM OVER THE CENTRAL ATLC. COMPUTER MODEL GUIDANCE SUGGESTS THAT THIS AREA OF ATMOSPHERIC LIFT IS EXPECTED TO INTERACT WITH THE SURFACE FRONTS OVER THE CENTRAL ATLC TO RESULT IN THE DEVELOPMENT OF A SURFACE LOW OVER THE CENTRAL ATLC DURING THE NEXT DAY...WHICH IS EXPECTED TO BE A 1016 MB SURFACE LOW NEAR 32N48W AT 01/0600 UTC. TO THE W OF THE FRONTS...FAIR WEATHER CONDITIONS ARE OCCURRING...WHERE SUBSIDENCE AND STABLE ATMOSPHERIC CONDITIONS ARE PRESENT IN THE VICINITY OF A SURFACE RIDGE. ALSO...ACROSS LOCATIONS IN THE CENTRAL AND E ATLC THAT ARE SE OF THE FRONTS...SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE IS SUPPORTING FAIR WEATHER CONDITIONS. THIS SURFACE RIDGE EXTENDS SOUTHWARD FROM A 1023 MB SURFACE HIGH NEAR 30N35W. THE SURFACE HIGH IS FORECAST TO MOVE SOUTHEASTWARD DURING THE NEXT DAY AND BE LOCATED NEAR 27N31W AS A 1021 MB SURFACE HIGH AT 01/0600 UTC. FARTHER TO THE E...A DEEP LAYER TROUGH IS PRESENT OVER THE E ATLC N OF 18N E OF 20W. THE DEEP LAYER TROUGH IS ASSOCIATED WITH A 1015 MB SURFACE LOW NEAR 24N18W. THIS SURFACE LOW IS FORECAST TO HAVE DISSIPATED BY 01/0600 UTC. LOW LEVEL CONVERGENCE AND ATMOSPHERIC INSTABILITY IN THE VICINITY OF THE SURFACE LOW ARE SUPPORTING SCATTERED SHOWERS FROM 22N-26N BETWEEN 17W-20W. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS S OF 12N E OF 58W WITH AN UPPER LEVEL HIGH NEAR 3N23W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS UPPER LEVEL RIDGE AND UPPER LEVEL HIGH IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ. THIS UPPER LEVEL DIVERGENCE IS ALSO SUPPORTING SCATTERED SHOWERS FROM 3N-7N BETWEEN 47W-53W. $$ COHEN