000 AXNT20 KNHC 292359 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU MAY 29 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. ...SPECIAL FEATURE... TROPICAL STORM ALMA MADE LANDFALL ALONG THE PACIFIC COAST OF NICARAGUA THIS AFTERNOON AND IS NOW LOCATED NEAR 12.9N 87.1W... OR NEAR THE HONDURAS/NICARAGUA BORDER ABOUT 115 NM S OF TEGUCIGALPA...AT 30/0000 UTC MOVING N 8 KT. MAXIMUM SUSTAINED WIND SPEED HAS DIMINISHED TO 45 KT WITH GUSTS TO 55 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB. ALMA IS EXPECTED TO CONTINUE MOVING INLAND ACROSS NORTHERN SECTIONS OF CENTRAL AMERICA WITH SQUALLY WEATHER SPREADING ACROSS THE FAR WESTERN CARIBBEAN OVER THE NEXT 24-36 HRS. ALTHOUGH THE WINDS WILL WEAKEN DUE TO ITS INTERACTION WITH LAND...HEAVY RAINFALL WILL CONTINUE OVER PORTIONS OF COSTA RICA...NICARAGUA...HONDURAS...EL SALVADOR...GUATEMALA...AND BELIZE AS A STEADY STREAM OF TROPICAL MOISTURE LIFTS N FROM THE PACIFIC. TOTAL RAINFALL ACCUMULATIONS OF 10-15" ARE POSSIBLE WITH ISOLATED AMOUNTS UP TO 20"... ESPECIALLY OVER THE HIGHER TERRAIN...INCREASING THE LIKELIHOOD OF DEVASTATING FLASH FLOODS. SOME REPORTED 48 HOUR RAINFALL TOTALS INCLUDE PANAMA CITY PANAMA 1.97" SANTIAGO PANAMA 5.55" DAVID PANAMA 5.75" SAN JOSE COSTA RICA 3.07" SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPEP1/WTPZ31 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE HAS MOVED PAST THE CAPE VERDE ISLANDS ALONG 31W S OF 15N MOVING W 15 KT. TPW PRODUCTS CONTINUE TO SHOW A WELL-DEFINED DEEP-LAYERED MOISTURE SURGE EXTENDING FROM THE TROPICS NWD TO ABOUT 21N EVEN THOUGH THERE IS VERY LITTLE SIGNATURE IN CONVECTIONAL SATELLITE IMAGERY. A SMALL INFLECTION IS NOTED WITHIN THE ITCZ AND ALL ASSOCIATED CONVECTION IS CONCENTRATED ALONG THE ITCZ AXIS ITSELF. LOW-LATITUDE TROPICAL WAVE ALONG 44W/45W S OF 8N...ABOUT 450 NM E OF FRENCH GUIANA...MOVING W 15 KT. THIS WAVE HAS CONTINUED TO BECOME MORE WELL-DEFINED OVER THE PAST SEVERAL DAYS...SPECIFICALLY ASSOCIATED WITH THE MOISTURE FIELD. IT IS EXPECTED TO REACH THE COAST OF SOUTH AMERICA BY THIS TIME TOMORROW AND WILL LIKELY INCREASE TSTM COVERAGE OVER THE GUIANAS OVER THE NEXT 2-3 DAYS. ALL ASSOCIATED CONVECTION IS CURRENTLY WITHIN THE ITCZ. TROPICAL WAVE LOCATED OVER THE CENTRAL CARIBBEAN NEAR 73W S OF 21N MOVING W 15-20 KT. ODDLY ENOUGH...THIS WAVE HAS MARKED THE LEADING EDGE OF A DRY SURGE ACROSS THE EASTERN CARIBBEAN AS IT RUNS INTO THE EXTREMELY MOIST ENVIRONMENT OVER THE WESTERN CARIBBEAN. THE AXIS HAS BECOME DIFFICULT TO LOCATED NOW THAT IT IS MOVING INTO A LARGE-SCALE CYCLONIC GYRE YET MIMIC-TPW PLACES IT NICELY NEAR THE GUAJIRA PENINSULA OF COLOMBIA. SCATTERED MODERATE CONVECTION EXTENDS FROM 15N-22N BETWEEN 67W-78W ALTHOUGH THIS IS LIKELY ALSO ASSOCIATED WITH A BROAD SURFACE TROUGH EXTENDING NE OF CENTRAL AMERICA. SCATTERED MODERATE/ISOLATED STRONG IS ALSO OVER NW VENEZUELA AND NORTHERN COLOMBIA. TROPICAL WAVE OVER THE GULF OF HONDURAS ALONG 85W S OF 20N MOVING W 10 KT. THE WAVE HAS BECOME WRAPPED INTO THE CIRCULATION OF T.S. ALMA OVER WESTERN NICARAGUA AND IS BECOMING INCREASINGLY INDISTINGUISHABLE FROM THE LARGE-SCALE PATTERN. IN FACT...A MORE WELL-DEFINED SURFACE TROUGH EXTENDS FROM HONDURAS TO NEAR JAMAICA WITH AN E/W LINE OF SCATTERED MODERATE CONVECTION LIFTING NWD FROM 15N-21N W OF 78W. THE WAVE AXIS WILL BE DROPPED FROM THE 30/0000 UTC ANALYSIS IN FAVOR OF THE TROUGH. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 12N10W 5N20W 6N31W 1N55W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION OFF THE COAST OF AFRICA S OF 10N BETWEEN 8W-15W. SCATTERED MODERATE/STRONG FROM 00N-5N BETWEEN 20W-30W. ISOLATED MODERATE WITHIN 120 NM OF AXIS W OF 31W INTO SOUTH AMERICA...WHERE COVERAGE BECOMES MORE NUMEROUS. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL HIGH REMAINS CENTERED ALONG THE PACIFIC COAST OF MEXICO NEAR MAZATLAN BUT THE RIDGE AXIS HAS SHIFTED W SINCE YESTERDAY...NOW EXTENDING NE ACROSS TEXAS. A SHARP UPPER TROUGH AXIS NOW STRETCHES ACROSS THE GULF FROM N FLORIDA TO 26N90W THEN TO THE ISTHMUS OF TEHUANTEPEC. MODERATE/STRONG SUBSIDENCE LIES W OF THE TROUGH AXIS WHILE DEEPER MOISTURE IS INCREASING TO THE E...CREEPING N FROM THE NW CARIBBEAN. A FEW PATCHES OF SHOWER ACTIVITY ARE MOVING W ACROSS THE CENTRAL GULF AND SW GULF BUT OTHERWISE MUCH OF THE AREA IS EXPERIENCING FAIR WEATHER. HOWEVER...TSTMS WHICH HAVE FORMED ACROSS THE YUCATAN PENINSULA AND CUBA COULD MOVE OFFSHORE WITHIN THE NEXT FEW HRS DUE TO THE SOUTHEASTERLY STEERING FLOW. CARIBBEAN... T.S. ALMA HAS MADE LANDFALL OVER WESTERN NICARAGUA AND IS ADVECTING DEEP TROPICAL MOISTURE FROM THE FAR EASTERN PACIFIC NWD ACROSS MUCH OF THE WESTERN CARIBBEAN W OF 75W. UPPER LEVEL OUTFLOW IS SPREADING AWAY FROM ALMA WITH AN UPPER HIGH CENTERED NEAR 17N81W...AND THE CIRRUS FLOWING E/SE TOWARDS THE EASTERN CARIBBEAN. ASIDE FROM CONVECTION DESCRIBED WITH THE TROPICAL WAVES...NUMEROUS MODERATE/STRONG CONVECTION HAS ALSO FLARED OVER EASTERN HONDURAS...NICARAGUA...AND THE ADJACENT WATERS FROM 10N-18N BETWEEN 82W-86W. THE CLEAREST SKIES EXTEND OVER THE SE CARIBBEAN ACROSS THE ABC ISLANDS...THE COAST OF VENEZUELA...AND THE WINDWARD ISLANDS DUE TO A DRYING ATMOSPHERE. ATLANTIC... THE SUBTROPICAL RIDGE REMAINS BROKEN OVER THE W ATLANTIC WITH SEVERAL SURFACE TROUGHS STILL STRUNG THROUGH THE AREA. ONE TROUGH OVER THE BAHAMAS IS PRODUCING SCATTERED SHOWERS/TSTMS OVER THE BAHAMAS FROM 23N-28N BETWEEN 73W-78W AND THE ASSOCIATED MOISTURE IS EXPECTED TO MOVE W ACROSS S FLORIDA BY FRI EVENING. ANOTHER SURFACE TROUGH EXTENDS FROM 31N58W TO 24N63W IS PRODUCING ISOLATED SHOWERS/TSTMS WITHIN 120 NM OF THE AXIS...ESPECIALLY IN THE VICINITY OF AN UPPER LOW NEAR 23N63W. FARTHER E...A SPRAWLING 1026 MB HIGH IS CENTERED NEAR 32N39W WITH LITTLE ACTIVE WEATHER ACROSS THE EASTERN/CENTRAL ATLANTIC. A LONGWAVE TROUGH AXIS EXTENDS FROM MADEIRA ISLAND SW TO 25N43W WITH 70-75 KT WESTERLY FLOW STRETCHING ACROSS THE CANARY ISLANDS INTO NW AFRICA. AN UPPER HIGH IS LOCATED FARTHER S NEAR THE CAPE VERDE ISLANDS AND IS PULLING SOME UPPER LEVEL MOISTURE FROM THE TROPICS BACK TOWARDS AFRICA. HOWEVER...DEEP MOISTURE REMAINS SCANT E OF 60W AND THUS ALL DEEP CONVECTION IS LIMITED TO THE ITCZ. $$ BERG