000 FXCA20 KWBC 161835 PMDCA TROPICAL DISCUSSION - INTERNATIONAL DESKS NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 234 PM EDT WED MAY 16 2012 COR DTG DISCUSSION FROM MAY 16/00 UTC: AN UPPER LEVEL RIDGE IS INITIALIZED WITH AXIS EXTENDING FROM THE EASTERN PACIFIC/SOUTHERN MEXICO... ACROSS CENTRAL AMERICA TO THE CENTRAL CARIBBEAN/NORTHWEST SOUTH AMERICA. A POLAR TROUGH OVER THE EASTERN USA/NORTHERN GULF OF MEXICO IS PRESSING AGAINST THIS AXIS. THROUGH 36-48 HRS THE TROUGH IS TO PULL TO THE EAST-NORTHEAST ACROSS THE EASTERN USA...MEANWHILE FAVORING THE GRADUAL EROSION AND WEAKENING OF THE RIDGE AXIS OVER SOUTHERN MEXICO/NORTHERN CENTRAL AMERICA. ANOTHER PERTURBATION IS TO CLOSELY FOLLOW...WITH TROUGH ACROSS SOUTHWEST USA TO NORTHERN STATES OF MEXICO BY 48 HRS...INTO THE NORTHERN GULF BY 72 HRS. THIS WILL ADD TO GRADUAL EROSION OF THE RIDGE OVER THE SOUTHERN STATES OF MEXICO/YUCATAN PENINSULA. AT LOW LEVELS...A POLAR TROUGH EXTENDS ACROSS THE EASTERN USA TO THE EASTERN GULF OF MEXICO...WHILE A POLAR RIDGE TO THE WEST LIES OVER THE CENTRAL PLAINS TO TEXAS. THE TROUGH SUSTAINS A WEAK BAROCLINIC BOUNDARY INTO THE GULF OF MEXICO...BUT THIS IS FORECAST TO WEAKEN THROUGH 24 HRS. UNDER INFLUENCE OF THE RIDGE TO THE WEST...AND MEANDERING TROUGH OVER THE EASTERN USA/GULF...A LONG FETCH NORTHERLY FLOW IS TO PERSIST ACROSS THE WESTERN/CENTRAL GULF OF MEXICO TO THE SOUTHERN STATES OF MEXICO. THIS WILL ENHANCE MOISTURE CONVERGENCE ACROSS PORTIONS OF CAMPECHE-YUCATAN-TABASCO AND CHIAPAS IN SOUTHERN MEXICO. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM/DAY THROUGH 30 HRS...AND 00-05MM/DAY AND MAXIMA OF 10MM/DAY THEREAFTER. OTHER ACTIVITY IS TO AFFECT MEXICO DF-PUEBLA-COLIMA/MICHOACAN... WHERE DIURNAL CONVECTION WILL RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM/DAY. THROUGH DAY 03 THE MAXIMA WILL INCREASE TO 15-30MM/DAY. ALTHOUGH UPPER LEVEL RIDGE TENDS TO ERODE OVER SOUTHERN MEXICO... OVER THE CARIBBEAN/CENTRAL AMERICA IT WILL BE MORE RESILIENT. DURING THE NEXT COUPLE OF DAYS IT WILL CENTER ON A HIGH OVER GULF OF FONSECA...WITH AXIS TO MEANDER EAST ACROSS HONDURAS TO THE CENTRAL CARIBBEAN BY 72-96 HRS. THE PERSISTENT RIDGE PATTERN WILL STEER SHORT WAVE PERTURBATIONS ACROSS CUBA AND THE BAHAMAS. THESE ARE TO INTERACT WITH SEA BREEZE CONVERGENCE TO ENHANCE CONVECTIVE DEVELOPMENT OVER THESE ISLANDS. OVER THE CENTRAL/NORTHWEST BAHAMAS EXPECTING ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM THROUGH 36-48 HRS...AND AGAIN BY 72-84 HRS. FURTHERMORE...AS AN UPPER LEVEL RIDGE PERSISTS OVER CENTRAL AMERICA...IT WILL VENT DEEP CONVECTION IN ASSOCIATION WITH AN INDUCED/INVERTED TROUGH OVER THE WESTERN CARIBBEAN. THE TROUGH EXTENDS NORTH FROM GULF OF HONDURAS TO THE YUCATAN CHANNEL/EASTERN GULF OF MEXICO. THIS TROUGH IS TO PERSIST DURING THE NEXT 84-96 HRS...WITH SOME OF THE MODELS SHOWING POSSIBLE STRENGTHENING OF THIS AXIS LATER IN THE CYCLE. HOWEVER...IN A HIGH SHEAR ENVIRONMENT...IT IS MORE LIKELY TO PERSIST AS AN OPEN TROUGH. ALONG THE BASE OF THE TROUGH EXPECTING CONVECTIVE ENHANCEMENT ACROSS WESTERN CUBA-BELIZE/QUINTANA ROO IN THE YUCATAN...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 50-100MM/DAY. THROUGH 72-96 HRS THIS IS FORECAST TO DECREASE TO 10-15MM/DAY AND MAXIMA OF 20-40MM/DAY. AS A TROUGH PERSISTS OVER NORTHERN CENTRAL AMERICA...THE BEST MOISTURE CONVERGENCE IS EXPECTED ACROSS THE SOUTHERN STATES OF MEXICO TO GUATEMALA-EL SALVADOR/HONDURAS AND PORTIONS OF NICARAGUA. OVER SOUTHERN MEXICO TO GUATEMALA EXPECTING RAINFALL AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-125MM/DAY THROUGH 36 HRS. THIS DECREASES TO 15-20MM/DAY AND MAXIMA OF 25-50MM THROUGH 84-96 HRS...WHILE OVER EL SALVADOR-HONDURAS AND NICARAGUA EXPECTING ACCUMULATION OF 25-50MM/DAY AND MAXIMA OF 75-125MM/DAY...FORECAST TO DECREASE THROUGH 84-96 HRS. BY 72-96 HRS MOST ACTIVE IS EXPECTED ALONG THE NORTH COAST WITH MAXIMA OF 40-80MM/DAY. MID LEVEL HIGH IS INITIALIZED OVER THE WINDWARD PASSAGE OF CUBA...ANCHORING A RIDGE OVER THE CENTRAL CARIBBEAN. UNDER PRESSURE FROM AFOREMENTIONED MID/UPPER LEVEL PERTURBATIONS...THIS RIDGE IS ALSO FORECAST TO WEAKEN THROUGH 48 HRS...TO BECOME NARROW AND ELONGATED LATER IN THE CYCLE. THIS SUSTAINS A MID LEVEL CAP ACROSS HISPANIOLA-PUERTO RICO/NORTHERN LEEWARD ISLANDS. THIS WILL BE STRONG ENOUGH TO DELAY ONSET OF DIURNAL CONVECTION...BUT NOT STRONG TO SUPPRESS IT. THE CAP WILL GRADUALLY WEAKEN THROUGH 42-48 HRS... ALLOWING FOR DEEPER MOISTURE TO POOL ACROSS THESE ISLANDS. THE GFS IS RESPONDING TO CHANGE IN ENVIRONMENTAL CONDITIONS BY SHOWING PWAT INCREASING FROM 35-40MM TO NEARLY 50MM BY 42-48 HRS...WITH K INDEX ALSO INCREASING TO THE LOW 30S IN RESPONSE TO THE DEEPER LAYER INSTABILITY IN THE AREA. INITIALLY...DIURNAL CONVECTION OVER THESE ISLANDS WILL RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM/DAY. THROUGH 48-72 HRS THIS WILL INCREASE TO 10-15MM/DAY AND MAXIMA OF 20-30MM/DAY. DOWNSTREAM FROM THE CARIBBEAN RIDGE...AN UPPER LEVEL TROUGH EXTENDS SOUTH ACROSS THE ISLAND CHAIN TO NORTHEAST VENEZUELA. THE TROUGH IS TO MEANDER OVER THE EASTERN CARIBBEAN ISLANDS THROUGH 36-42 HRS... THEN MOVE EAST OF THE ISLAND CHAIN BY 60-72 HRS...WHILE TRAILING SOUTH TO GUYANA/EASTERN VENEZUELA. SHORT WAVE PERTURBATIONS ROUNDING THE BASE OF THE TROUGH WILL ENHANCE CONVECTION ACROSS THE SOUTHERN WINDWARD ISLANDS/NORTHEAST VENEZUELA. AT LOW LEVELS...THE ATLANTIC ITCZ MEANDERS ALONG THE NORTHERN GUIANAS INTO VENEZUELA. THE TROUGH ALOFT IS TO INTERACT WITH THE CONVERGENCE ZONE TO ENHANCE ACTIVITY ACROSS THE GUIANAS TO NORTHEAST VENEZUELA...WHERE WE EXPECT RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM/DAY. PERTURBATIONS IN THE EASTERLIES...INITIALIZED AT 12UTC INITIAL 24 36 48 60 72 84 TYPE 61W/62W 64W 67W 70W 73W 75W 78W TW 71W 74W 76W 78W 80W 82W 84W EW TROPICAL WAVE ALONG 61W/62W AND SOUTH OF 12N IS INTERACTING WITH THE ITCZ NORTH OF GUYANA AND MID/UPPER TROUGH OVER THE EASTERN CARIBBEAN...FAVORING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM/DAY AS IT ENTERS NORTHEAST VENEZUELA/SOUTHERN WINDWARD ISLANDS. OVER CENTRAL-WESTERN VENEZUELA IT IS TO THEN FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM/DAY. MOST INTENSE TO AFFECT LAKE MARACAIBO REGION IN NORTHWEST VENEZUELA-SANTANDERES IN COLOMBIA/SIERRA NEVADA DE SANTA MARTA WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM/DAY. OVER EJE CAFETERO IN COLOMBIA TO THE DARIEN IN PANAMA IT WILL RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM. AN EASTERLY WAVE ALONG 71W AND SOUTH OF 16N IS TO TRIGGER SCATTERED CONVECTION ACROSS NORTHERN COLOMBIA WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM/DAY...SIMILARLY ACROSS EJE CAFETERO TO THE DARIEN IN PANAMA. OVER WESTERN PANAMA/COSTA RICA EXPECT ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF 35-70MM/DAY. ALSO AT 850 HPA...A BUILDING CELL OF THE SUBTROPICAL RIDGE IS TO THEN TIGHTEN THE PRESSURE GRADIENT ACROSS THE CENTRAL/WESTERN ATLANTIC TO THE EASTERN CARIBBEAN ISLANDS. IN THIS PATTERN WINDS WILL GRADUALLY VEER TO THE SOUTHEAST WHILE INTENSITY INCREASES FROM 10-15KT TO 20-25KT. MARINERO...DGOA/MARN (EL SALVADOR) SOLORZANO...SMN (HONDURAS) GALVEZ...HPC (USA) $$