000 AXNT20 KNHC 061709 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST FRI MAR 06 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 1200 UTC SURFACE ANALYSIS...AND SATELLITE IMAGERY THROUGH 1645 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N8W 3N17W CROSSING THE EQUATOR NEAR 26W EXTENDING TO 2S34W INTO NE BRAZIL NEAR 3S45W. SCATTERED MODERATE CONVECTION IS FROM 3N-7N BETWEEN 9W-17W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE IS PRESENT ACROSS MUCH OF THE GULF REGION...WHERE STABLE ATMOSPHERIC CONDITIONS...DEEP LAYER DRY AIR...AND SUBSIDENCE ARE PRESENT. AS A RESULT...GENERALLY FAIR WEATHER CONDITIONS PERSIST ACROSS THE GULF REGION. THE SUBSIDENCE IS BEING SUPPORTED BY A SURFACE RIDGE THAT EXTENDS SOUTHWESTWARD FROM A SURFACE HIGH IN THE W ATLC NEAR 35N69W. THE FLOW AROUND THIS SURFACE RIDGE IS RESULTING IN E TO SE SURFACE WINDS ACROSS MUCH OF THE GULF. CARIBBEAN SEA... SUBSIDENCE RESULTING FROM CONFLUENCE IN WESTERLY FLOW ALOFT IS LIMITING DEEP CONVECTION ACROSS MUCH OF THE CARIBBEAN...WHERE GENERALLY FAIR WEATHER CONDITIONS ARE OCCURRING. DEEP LAYER DRY AIR IS PRESENT ACROSS MUCH OF THE W AND CENTRAL CARIBBEAN... WHILE UPPER LEVEL MOISTURE IS BEING DRAWN NORTHEASTWARD ACROSS THE E CARIBBEAN. ALSO...A DEEP LAYER TROUGH OVER THE W ATLC IS ASSOCIATED WITH A DISSIPATING SURFACE STATIONARY FRONT IN THE NE CARIBBEAN THAT EXTENDS FROM 17N66W TO E OF PUERTO RICO NEAR 18N65W INTO THE SW NORTH ATLC. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS ALONG AND WITHIN 60 NM EITHER SIDE OF THIS FRONT. ADDITIONALLY...PATCHES OF LOW LEVEL MOISTURE ARE BEING ADVECTED SOUTHWESTWARD ACROSS THE CARIBBEAN...WITH SCATTERED SHOWERS EMBEDDED WITHIN THESE PATCHES OF LOW LEVEL MOISTURE. THE GREATEST CONCENTRATION OF THESE SHOWERS IS FROM 15N-18N BETWEEN 73W-79W. ALSO...A GALE WARNING IS IN EFFECT FOR LOCATIONS WITHIN 90 NM OF THE COLOMBIAN COAST WITH THE INCREASED SURFACE WINDS RESULTING FROM THE INCREASED SURFACE PRESSURE GRADIENT ACROSS THE CARIBBEAN. ATLANTIC OCEAN... THE AFOREMENTIONED DEEP LAYER TROUGH OVER THE W ATLC IS ASSOCIATED WITH A SURFACE FRONT THAT EXTENDS FROM THE NE CARIBBEAN TO E OF PUERTO RICO NEAR 18N65W TO A 1014 MB SURFACE LOW NEAR 28N54W TO 32N50W TO NE OF THE DISCUSSION AREA. THIS SURFACE FRONT IS A DISSIPATING SURFACE STATIONARY FRONT S OF 21N...A SURFACE COLD FRONT FROM 21N TO THE SURFACE LOW...AND A SURFACE STATIONARY FRONT N OF THE SURFACE LOW. THIS SURFACE LOW IS ASSOCIATED WITH GALE FORCE WINDS. THE DEEP LAYER TROUGH IS ALSO ASSOCIATED WITH A SURFACE TROUGH THAT EXTENDS FROM 15N54W TO 24N52W TO 31N49W. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THE FRONT S OF 22N...AND NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 90 NM EITHER SIDE OF THE FRONT ALONG AND N OF 22N. ALSO...LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH. THIS ACTIVITY IS BEING SUPPORTED BY UPPER LEVEL DIVERGENCE ASSOCIATED WITH TWO UPPER LEVEL JET MAXIMA IN THE VICINITY OF THE SURFACE LOW. THE SURFACE LOW IS FORECAST TO MOVE NORTHEASTWARD DURING THE NEXT DAY AND BE LOCATED NEAR 30N51W AT 07/1200 UTC AS A 1010 MB SURFACE LOW. TO THE W OF THE FRONT...A RELATIVELY COOLER AND DRIER AIRMASS IS PRESENT...WHERE SUBSIDENCE AND ATMOSPHERIC STABILITY ARE SUPPORTING GENERALLY FAIR WEATHER CONDITIONS. THIS SUBSIDENCE IS BEING SUPPORTED BY A SURFACE RIDGE THAT EXTENDS SOUTHWESTWARD FROM A 1034 MB SURFACE HIGH OVER THE W ATLC NEAR 35N69W. THIS SURFACE HIGH IS FORECAST TO MOVE SOUTHWARD DURING THE NEXT DAY AND BE LOCATED NEAR 32N70W AS A 1030 MB SURFACE HIGH AT 07/1200 UTC. ACROSS THE E ATLC...AN UPPER LOW IS LOCATED NEAR 24N29W. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS UPPER LOW IS SUPPORTING SCATTERED SHOWERS FROM 27N-30N BETWEEN 21W-29W. HOWEVER...SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE IS INHIBITING DEEP CONVECTION ACROSS MUCH OF THE E ATLC. ACROSS THE TROPICAL ATLC...AN UPPER RIDGE IS S OF 8N E OF 54W WITH AN UPPER HIGH NEAR 3N33W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS UPPER HIGH AND UPPER RIDGE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ. $$ COHEN