000 AXNT20 KNHC 282344 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED MAY 28 2008 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE MOVING ACROSS THE CAPE VERDE ISLANDS ALONG 24W/25W S OF 18N MOVING W 15-20 KT. THE TPW PRODUCT INDICATES A SIGNIFICANT DEEP-LAYERED MOISTURE SURGE EXTENDING OFF THE AFRICAN COAST TO NEAR 30W. SCATTERED SHOWERS/ISOLATED MODERATE CONVECTION IS CONCENTRATED S OF THE ISLANDS NEAR THE ITCZ FROM 3N-8N BETWEEN 23W-33W. TROPICAL WAVE ALONG 39W S OF 9N...OR 800 NM E OF FRENCH GUIANA...MOVING W 15 KT. ALTHOUGH THIS WAVE HAS BEEN DIFFICULT TO LOCATE FOR SEVERAL DAYS...THE CIMSS MIMIC-TPW PRODUCT CURRENTLY SHOWS A SMALL INFLECTION OF DEEP MOISTURE NEAR THE ANALYZED AXIS...PROBABLY AS A RESULT OF THE WAVE TO THE E AMPLIFYING THE PATTERN A BIT. NO SIGNIFICANT CONVECTION. TROPICAL WAVE MOVING ACROSS PUERTO RICO AND VENEZUELA ALONG 65W/66W S OF 21N MOVING W 15-20 KT. THE WAVE AXIS HAS BECOME STRETCHED N/S AND BECOME SOMEWHAT LESS DEFINED OVER THE PAST 24 HRS. SURFACE OBSERVATIONS AND SCATTEROMETER DATA INDICATE A 15-20 KT SURGE IN THE TRADES OCCURRING E OF THE AXIS PAST THE LESSER ANTILLES BACK INTO THE ATLANTIC. NUMEROUS SHOWERS/SCATTERED TSTMS EXTEND ACROSS PUERTO RICO AND THE VIRGIN ISLANDS FROM 17N-22N BETWEEN 62W-68W. SCATTERED MODERATE/STRONG CONVECTION IS ALSO MOVING W ACROSS MUCH OF VENEZUELA FROM THE GUIANA HIGHLANDS NW TO LAKE MARACAIBO. TROPICAL WAVE LIES ACROSS PANAMA AND THE WESTERN CARIBBEAN ALONG 81W S OF 19N MOVING W 15 KT. THE WAVE IS NOW INTERACTING WITH THE LARGE AREA OF LOW PRES EXTENDING FROM THE FAR EASTERN PACIFIC NE ACROSS COSTA RICA AND NICARAGUA...MAKING IT DIFFICULT TO ISOLATE A WELL-DEFINED AXIS. HOWEVER...THE WAVE'S INFLUENCE HAS BEGUN TO DRAW ABUNDANT MOISTURE/SCATTERED SHOWERS AND TSTMS NWD FROM COLOMBIA ACROSS THE W/CENTRAL CARIBBEAN...AND BEGINNING TO OVERSPREAD HISPANIOLA AND JAMAICA. SCATTERED MODERATE CONVECTION S OF 19N BETWEEN 70W-85W. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N10W 5N17W 6N24W 4N52W. NUMEROUS MODERATE/STRONG CONVECTION MOVING OFF THE AFRICAN COAST S OF 12N BETWEEN 7W-18W. ISOLATED MODERATE WITHIN 120 NM OF AXIS BETWEEN 23W-33W AND W OF 45W INTO THE GUIANAS. ...DISCUSSION... GULF OF MEXICO... A LARGE BLOCKING UPPER LEVEL HIGH IS CENTERED ALONG THE W COAST OF MEXICO WITH A RIDGE AXIS CONTINUING NE ACROSS THE NORTHERN COAST OF THE GULF OF MEXICO. ANOTHER WEAKER UPPER HIGH IS CENTERED NEAR SOUTH FLORIDA...AND IS SEPARATED BY THE FIRST RIDGE BY A CYCLONIC SHEAR AXIS WHICH EXTENDS FROM THE FLORIDA PANHANDLE TO THE BAY OF CAMPECHE. ALL TOLD...MAINLY MODERATE SUBSIDENCE COVERS THE ENTIRE REGION WITH ONLY PASSING PATCHES OF LOW/MID LEVEL CLOUDINESS AND EMBEDDED SHOWERS MOVING FROM E TO W. A WEAK SURFACE RIDGE AXIS ALSO LIES ALONG THE N GULF COAST WITH LIGHT/MODERATE WINDS OVER THE OFFSHORE WATERS...BUT THIS FEATURE IS BEING WEAKENED BY A COLD FRONT WHICH IS CURRENTLY MOVING ACROSS THE DEEP SOUTH TO TEXAS. DEEPER MOISTURE HAS RETURNED TO THE SE AND S/CENTRAL PART OF THE GULF WITH SCATTERED SHOWERS/TSTMS S OF 26N E OF 85W AND NEAR THE YUCATAN COAST. CARIBBEAN... THE UPPER LEVEL PATTERN OVER THE CARIBBEAN IS DOMINATED BY AN UPPER HIGH OVER NORTHERN COLOMBIA WITH SW/W FLOW ALOFT SPREADING FROM CENTRAL AMERICA EWD TO THE LESSER ANTILLES. A STRONG AREA OF LOW PRES OVER THE FAR EASTERN PACIFIC...WHICH HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO...IS CENTERED JUST W OF THE NICOYA PENINSULA OF COSTA RICA AND IS DRAWING COPIOUS DEEP-LAYERED MOISTURE NWD ACROSS PANAMA...COSTA RICA...NICARAGUA...AND MUCH OF THE WESTERN CARIBBEAN WATERS. HEAVY RAIN HAS BEEN FALLING OVER THESE AREAS AND IS EXPECTED TO CONTINUE FOR THE NEXT DAY OR SO THEN LIFT N TO OTHER PORTIONS OF CENTRAL AMERICA...POSING A THREAT OF FLASH FLOODING AND MUDSLIDES. OVER THE PAST 24 HRS...PANAMA CITY PANAMA HAS OBSERVED 1.73" AND SAN JOSE COSTA RICA HAS REPORTED 0.79". ALSO...SOME OF THE CONVECTIVE ACTIVITY OVER THE W/CENTRAL CARIBBEAN WILL LIFT N AND BEGIN TO PRODUCE WIDESPREAD SHOWERS/TSTMS OVER JAMAICA...THE CAYMAN ISLANDS...AND PARTS OF CUBA OVER THE NEXT 48 HRS. FARTHER E...A DRIER AIR MASS HAS BEGUN TO FILTER IN ACROSS THE EASTERN CARIBBEAN AND LESSER ANTILLES BEHIND THE TROPICAL WAVE ALONG 65W/66W. THIS AIR MASS WILL SLOWLY CREEP W AND REACH TO NEAR 72W BY FRI EVENING. WEST ATLANTIC... FAST UPPER LEVEL FLOW EXTENDS ACROSS MUCH OF THE CONTINENTAL U.S. INTO THE NW ATLANTIC...WITH AN EMBEDDED SHORTWAVE TROUGH JUST E/SE OF BERMUDA FROM 32N62W TO 25N63W. THIS TROUGH CAUSED THE NORTHERN EXTENSION OF THE EASTERN CARIBBEAN TROPICAL WAVE TO BREAK OFF...AND LEAVE A SEGMENT FROM 29N59W TO 23N64W. NUMEROUS MODERATE CONVECTION HAS DEVELOPED NEAR THIS TROUGH FROM 23N-28N BETWEEN 59W-65W AS WELL AS WITHIN 270 NM NE OF PUERTO RICO. FARTHER W...A WEAK UPPER LOW IS CENTERED OVER THE CENTRAL BAHAMAS AND HAS BEEN PRODUCING ISOLATED SHOWERS/TSTMS MAINLY NE OF THE ISLAND CHAIN FROM 22N-25N BETWEEN 70W-76W. OTHERWISE A STRONG UPPER HIGH NEAR 27N72W IS PRODUCING MODERATE/STRONG SUBSIDENCE N OF 24N W OF 70W WITH FAIR WIND/SKY CONDITIONS. EAST/CENTRAL ATLANTIC... A MID/UPPER LOW IS LOCATED S OF THE AZORES NEAR 31N30W WITH A TROUGH EXTENDING SW TO 20N40W THEN PARTIALLY CUT-OFF TO 15N50W. A 70-95 KT JET LIES ON THE SE SIDE OF THE TROUGH FROM 26N30W NE TO 30N20W THEN TURNS E ACROSS THE CANARY ISLANDS AND MOROCCO. THERE IS VERY LITTLE AVAILABLE MOISTURE OVER THE E ATLANTIC E OF 55W SO THE REGION IS PRACTICALLY VOID OF DEEP CONVECTION. AN UPPER HIGH IS CENTERED OVER THE CAPE VERDE ISLANDS...AND COUPLED WITH THE UPPER TROUGH...IS PULLING ONLY HIGH LEVEL MOISTURE FROM THE DEEP TROPICS TO THE CANARY ISLANDS. $$ BERG