000 AXNT20 KNHC 131046 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU APR 13 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 7N10W 1N20W EQ30W 1S40W 2S45W. SMALL CLUSTERS OF MODERATE CONVECTION ARE WITHIN 250 NM ON EITHER SIDE OF THE AXIS W OF 15W. A SFC TROUGH IS LOCATED TO THE N OF THE AXIS ALONG 34W FROM 3N-9N ENHANCING SMALL-SCALE SHOWERS AND TSTMS. ...DISCUSSION... THE GULF OF MEXICO... MID-UPPER LEVEL RIDGING EXTENDS FROM AN UPPER HIGH IN THE EPAC AND STRETCHES ACROSS MEXICO...THE CENTRAL U.S. AND MUCH OF THE GULF OF MEXICO. MID-UPPER CLOUDINESS IS FAIRLY WIDESPREAD ACROSS MUCH OF THE AREA EXCEPT FOR THE SE CORNER WHERE STRONG SUBSIDENCE IS HOLDING ON. THIS UPPER LEVEL MOISTURE IS ADVECTED FROM THE EPAC ACROSS MEXICO AND THEN SSWARD ON THE E SIDE OF THE RIDGE IN THE GULF. A FEW SHOWERS MAY BE EMBEDDED IN THIS MOISTURE ESPECIALLY FROM 25N-28N. DRIER AIR IS ENTERING THE N U.S. GULF COAST AT THIS TIME BEHIND THE PATCH OF MOISTURE. A FEW SHOWERS ARE STREAMING WWD ACROSS THE FL KEYS AND THE STRAITS ASSOCIATED WITH AN UPPER TROUGH IN THE NW CARIBBEAN. AT THE SURFACE...A 1026 MB DOMINATES THE AREA PRODUCING GENERALLY FAIR WEATHER. SURFACE HIGH PRESSURE IS EXPECTED TO REMAIN IN CONTROL ACROSS THE AREA THRU FRI. THEREAFTER...THE HIGH PRES SYSTEMS WILL MOVE TO THE EAST OF THE REGION ALLOWING S/SW RETURN FLOW TO DEVELOP POSSIBLE ENHANCING SOME SHOWER ACTIVITY IN THE N GULF OVER THE WEEKEND. THE CARIBBEAN SEA AND THE ATLANTIC OCEAN W OF 60W... AN UPPER TROUGH TO THE E OF THE GULF RIDGE HAS BEEN STUCK IN THE NW CARIBBEAN MUCH OF THE WEEK. THIS TROUGH APPEARS TO HAVE BECOME SOME-WHAT CUT-OFF IN THE AREA. A 1010 MB SFC LOW IS LOCATED IN THE E BAHAMAS NEAR 21N72W AND SITS ON A STATIONARY FRONT WHICH EXTENDS NEWD FROM THE LOW TO BEYOND 32N56W. AN UPPER LOW IS CENTERED TO THE W OF THE SFC LOW IN THE CENTRAL BAHAMAS. UPPER LEVEL DIVERGENCE AND SFC FORCING IS PRODUCING A SHIELD OF OVERCAST SKIES...SCATTERED SHOWERS AND POSSIBLE TSTMS FROM 21N-32N BETWEEN 58W-73W. THE MOST ORGANIZED SHOWER ACTIVITY IS WITHIN 200 NM OF THE STATIONARY FRONT AND THE NEAR THE UPPER LOW N OF CUBA. THE UPPER LOW APPEARS TO DRIFTING TO THE SW. A SFC TROUGH IS DRAPED FROM THE LOW SWD OVER HISPANIOLA. SAN JUAN DOPPLER RADAR INDICATES A BATCH OF SOLID MODERATE RAIN WITH EMBEDDED TSTMS TO THE W OF THE ISLAND. CONSIDERABLE MOISTURE IS DRAWN NWD FROM THE EPAC AND S AMERICA ON THE E SIDE OF THE TROUGH AXIS AND IS RACING NEWARD MOVING INTO THE DEEP MOISTURE NEAR PUERTO RICO AND HISPANIOLA. VERY DRY/STABLE AIR IS TO THE W OF THE TROUGH AXIS ACROSS THE NW CARIBBEAN KEEPING SKIES MOSTLY CLEAR FROM CUBA TO NICARAGUA. GFS SUGGESTS THAT THE SFC LOW WILL BEGIN TO PULL NEWARD TOMORROW AS THE UPPER TROUGH BEGINS TO FLATTEN. THE UNSETTLED WEATHER WILL CONTINUE TO SHIFT SLIGHTLY EWD TOMORROW BEFORE BECOME SOMEWHAT DIFFUSE BY THE WEEKEND. THE DEEPEST MOISTURE WILL CONTINUE NEAR PUERTO RICO AND HISPANIOLA NEWD TO THE CENTRAL ATLC TODAY. THE REST OF THE ATLANTIC OCEAN... A RIDGE/TROUGH/RIDGE UPPER LEVEL PATTERN DOMINATES THE REMAINDER OF THE ATLANTIC OCEAN. A RATHER BROAD FLATTENING RIDGE STRETCHES FROM S AMERICA TO BEYOND 32N46W. SCATTERED STRATOCUMULUS CLOUDS ARE FAIRLY WIDESPREAD UNDER THE RIDGE. A DEEP-LAYER TROUGH COVERS A GOOD PORTION OF THE CENTRAL AND EASTERN ATLC WATERS...NAMELY FROM 20W-40W N OF 20N. THE ONLY SFC FEATURE TO MENTION IN THE AREA IS A 1013 MB LOW UNDERNEATH THE UPPER TROUGH. THERE ARE SOME SCATTERED SHOWERS SPIRALING AROUND THE LOW MOSTLY WITHIN 200 NM OF THE CENTER. GFS/NOGAPS SUGGEST THAT THE SFC LOW WILL DISSIPATE WITHIN THE NEXT 36 HOURS. A 80-100KT SWLY JET ORIGINATES ON THE S SIDE OF THE UPPER LOW AND STRETCHES TO PORTUGAL NEAR 37N9W. UPPER LEVEL DIFFLUENCE IS PRODUCING AN AREA OF SHOWERS AND TSTMS TO THE RIGHT OF THE AXIS FROM 25-33N BETWEEN 10W-23W. THIS UPPER LOW IS EXPECTED TO RACE NEWARD LEAVING A NEAR ZONAL WESTERLY UPPER LEVEL PATTERN ACROSS THE CENTRAL AND E ATLC BY SAT. A RATHER LARGE UPPER HIGH IS LOCATED TO THE S OF THE DEEP-LAYER TROUGH OVER W AFRICA WITH PLENTY OF DRY AIR ALOFT OVER THE W PART OF THE CONTINENT BETWEEN 7N-18N. BROAD WEAK RIDGING EXISTS IN THE TROPICAL ATLC LIMITING LARGE CLUSTERS OF CONVECTION IN THE ITCZ. A WEAK SFC TROUGH HAS FORMED ALONG 34W FROM 3N-9N ENHANCING SHOWERS WITHIN A FEW HUNDRED MILES NEAR THE TROUGH AXIS. GFS CARRIES THIS TROUGH WWD ENHANCING CONVECTION NEAR IT. $$ CANGIALOSI