000 FXCA20 KWBC 061851 PMDCA TROPICAL DISCUSSION - INTERNATIONAL DESKS NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 151 PM EST FRI NOV 06 2009 AT 15UTC...TD IDA CENTERED NEAR 15.0N 84.0W...WITH MINIMAL CENTRAL PRESSURE OF 1007 HPA AND MAXIMUM SUSTAINED WINDS OF 40KT. SEE TPC BULLETIN FOR UPDATES. DISCUSSION FROM NOV 06/0000 UTC. AT MID/UPPER LEVELS...A SOUTHERN STREAM SHORT WAVE TROUGH WILL ENTER THE NORTHWEST STATES OF MEXICO THROUGH 42-48 HRS...WITH CLOSED CIRCULATION ALONG THE BORDER BETWEEN ARIZONA-SONORA MEXICO. THROUGH 72 HRS THE LOW WILL LIFT TO THE NORTHWEST... DRAGGING THE TROUGH ACROSS NORTHEAST MEXICO. ALTHOUGH MODELS SHOW STRONG ROTATION IN ASSOCIATION WITH THIS SYSTEM...AVAILABLE MOISTURE IS LACKING. THE REGIONAL NAM IS THE ONLY MODEL THAT SHOWS SIGNIFICANT RAINFALL AMOUNTS ON THE NORTHERN STATES OF CHIHUAHUA-COAHUILA...WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM. THE GFS...IN CONTRAST...ONLY SHOWS TRACE RAINFALL AMOUNTS... AND IN OUR FORECAST WE ARE GOING WITH THE LESSER AMOUNTS. AS THE 500 HPA TROUGH ENTERS MEXICO...IT WILL INTERACT WITH A MEANDERING SHORT WAVE TROUGH OVER THE WESTERN GULF/ SOUTHERN MEXICO. EARLY IN THE PERIOD THE TROUGH WILL REMAIN NEARLY STATIONARY ALONG 96W/97W TO 10N. BY 42-48 HRS... HOWEVER...IT WILL START TO PULL EAST AND NORTH ALONG 92W/93W...AND BY 72 HRS IT IS TO RAPIDLY DAMPEN WHILE SHEARING TO THE NORTHEAST. AT LOW LEVELS...IT SUPPORTS AN INDUCED/INVERTED TROUGH ALONG 90W/92W. CONSISTENT WITH THE PREVIOUS FORECASTS...THIS FEATURE IS FORECAST TO WEAKEN THROUGH 36-48 HRS WHILE GRADUALLY TILTING FROM SOUTHEAST TO NORTHWEST ACROSS THE GULF. AN ILL ORGANIZED LOW/TROUGH WILL THEN REMAIN TO THE EAST OF VERACRUZ MEXICO. AS THE TROUGH WEAKENS/TILTS...THE FLOW ACROSS SOUTHERN MEXICO WILL SHIFT AND BECOME NEARLY PARALLEL TO THE GULF COAST. THE WINDS ARE TO ALSO DECREASE IN INTENSITY. THIS WILL LEAD TO A DECREASE IN OROGRAPHICALLY INDUCED CONVECTION ACROSS SOUTHERN MEXICO. ACROSS TABASCO-CENTRAL/NORTHERN CHIAPAS-NORTHERN OAXACA AND SOUTHERN VERACRUZ EXPECT RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM/DAY THROUGH 36-42 HRS. AFTERWARDS...MOST INTENSE CONVECTION IS EXPECTED OFF THE COAST. FURTHERMORE...AS THE MID/UPPER TROUGH DEEPENS ACROSS THE SOUTHWEST USA/NORTHWEST MEXICO...IT WILL SUSTAIN THE NORTHWARD AMPLIFICATION OF A RIDGE ACROSS THE SOUTHEAST/ EASTERN USA TO THE WESTERN ATLANTIC. THE MID/UPPER LEVEL RIDGE WILL REACH MAXIMUM AMPLITUDE BETWEEN 48-72 HRS. A POLAR TROUGH LIES TO THE EAST...AND AS THE RIDGE OVER THE CONTINENT AMPLIFIES...THE TROUGH IS THEN FORECAST TO DEEPEN. AT 24 HRS THE TROUGH WILL EXTEND BETWEEN 55W-85W AND TO THE NORTH OF 26N. AT 60-72 HRS...THE TROUGH IS TO THEN AMPLIFY ALONG 35N 50W...25N 60W TO NORTH OF HISPANIOLA. AT 96-108 HRS A CLOSED LOW WILL FORM ALONG THE BASE OF THE TROUGH NEAR 23N 60W...WITH AXIS TO SIMULTANEOUSLY DEEPEN INTO THE EASTERN CARIBBEAN/OFF THE COAST OF VENEZUELA. THIS WILL BRING COLD AIR ADVECTION ALOFT TO THE NORTHEAST CARIBBEAN ISLANDS...MOST SIGNIFICANT ACROSS THE DOMINICAN REPUBLIC-PUERTO RICO...WHERE IT IS LIKELY TO SUSTAIN AN INCREASE IN CONVECTION. AT LOW LEVELS AN ELONGATED FRONT TRAILS ACROSS THE NORTHWEST BAHAMAS-FLORIDA KEYS TO THE GULF OF MEXICO. THROUGH 30-36 HRS IT WILL MOVE TO THE NORTHWEST/CENTRAL BAHAMAS...ALONG THE NORTHWEST COAST OF CUBA/STRAITS OF FLORIDA TO THE WESTERN GULF OF MEXICO. BY 36-48 HRS IT WILL MEANDER ACROSS THE CENTRAL BAHAMAS...THEN WEST ALONG 22N THROUGH CUBA TO THE GULF. AT 48-60 HRS IT WILL LIE ACROSS THE TURKS/SOUTHEAST BAHAMAS-MEANDERING WEST ACROSS CUBA ALONG 22N INTO THE GULF OF MEXICO. BY 72-84 HRS THE FRONT WILL START BOWING TOWARDS NORTHERN HISPANIOLA...WHILE PIVOTING OVER THE TURKS/ SOUTHEAST BAHAMAS-CENTRAL/WESTERN CUBA TO THE GULF OF MEXICO. OVER THE NORTHWEST-CENTRAL BAHAMAS IT IS TO INITIALLY FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM/DAY IN ISOLATED TO SCATTERED CONVECTION. ACROSS THE CENTRAL/SOUTHEAST BAHAMAS THIS WILL INCREASE TO 20-35MM/DAY...WITH LOCALIZED MAXIMA IN EXCESS OF 50MM QUITE POSSIBLE BY 60-72 HRS. FURTHERMORE...THE GFS SHOWS A FRONTAL SHEARLINE DEVELOPING AHEAD OF THIS FRONT...WITH BOUNDARY AT 1000 HPA FORECAST TO MOVE FROM THE SOUTHEAST BAHAMAS/HAITI EARLY IN THE CYCLE TO PUERTO RICO/EASTERN HISPANIOLA BY 24-36 HRS. IT IS TO THEN MEANDER BETWEEN EASTERN HISPANIOLA/WESTERN PUERTO RICO THROUGH 48-60 HRS...AND BY 72-84 HRS IT WILL SHIFT ACROSS THE VIRGIN ISLANDS-EASTERN PUERTO RICO. IN ADDITION TO SUSTAINING A SLIGHT INCREASE IN LOW LEVEL CONVERGENCE... THIS WILL SUSTAIN A SYNOPTIC SCALE NORTHEASTERLY FLOW ACROSS THE NORTHEAST CARIBBEAN ISLANDS. ACROSS THE DOMINICAN REPUBLIC-PUERTO RICO AND THE VIRGIN ISLANDS WE EXPECT A SLIGHT INCREASE IN CONVECTION...WITH RAINFALL AMOUNTS OF 05-10MM/DAY. MAXIMA OF 15-25MM WILL CONCENTRATE OVER THE DOMINICAN REPUBLIC AND PUERTO RICO ON DAY 02...TO INCREASE TO 20-35MM/DAY ON DAY 03. AN UPPER LEVEL RIDGE IS INITIALIZED OVER NORTHERN SOUTH AMERICA/CENTRAL-EASTERN CARIBBEAN...WITH AXIS CENTERING ON A CLOSED 250 HPA HIGH NORTH OF LA GUAJIRA PENINSULA. THE RIDGE PATTERN WILL PERSIST THROUGH 72 HRS...BUT IT TENDS TO WEAKEN NORTH OF THE ISLANDS AS THE AFOREMENTIONED TROUGH AMPLIFIES TO THE SOUTH. AT 500 HPA IT REFLECTS AS A SHORT WAVE RIDGE OVER THE EASTERN/CENTRAL CARIBBEAN. THIS SUSTAINS A WEAK SUBSIDENCE CAP ACROSS THE EASTERN CARIBBEAN ISLANDS...WITH LOCAL RADIOSONDE OBSERVATIONS SHOWING INVERSION HEIGHT AROUND 700-650 HPA. THE GFS IS FORECASTING THIS PATTERN TO PERSIST DURING THE NEXT 60-72 HRS...WITH WEAKENING BY 72-96 HRS AS THE TROUGH INTRUDES THE NORTHEAST CARIBBEAN. TD IDA...OVER NORTHEAST HONDURAS/NICARAGUA...WILL MOVE TO THE WESTERN CARIBBEAN EARLY THIS PERIOD. AS INDICATED BY THE TPC...THE SYSTEM IS EXPECTED TO GRADUALLY STRENGTHEN WHILE MOVING TO THE NORTHWEST TOWARDS THE YUCATAN CHANNEL DURING THE NEXT THREE DAYS. SOME RESIDUAL CONVECTION IS EXPECTED ACROSS NORTHEAST NICARAGUA TO RESULT IN ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM/DAY. OVER NORTHEAST HONDURAS...TO CONCENTRATE BETWEEN ROATAN/LA CEIBA-PUERTO LEMPIRA...EXPECT ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-40MM/DAY. AS THE SYSTEM EMERGES OVER THE WESTERN CARIBBEAN...CONVECTION IS EXPECTED TO INCREASE ACROSS THE CAYMAN ISLANDS AND THE YUCATAN PENINSULA. OVER THE CAYMAN ISLANDS EXPECT ACCUMULATION OF 15-25MM/DAY AND MAXIMA OF 40-70MM...WHILE OVER THE YUCATAN/NORTHERN BELIZE INITIALLY EXPECT ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON DAY 03 THIS WILL INCREASE TO 15-25MM/DAY AND MAXIMA OF 40-70MM/DAY WHILE CONCENTRATING ACROSS QUINTANA ROO/NORTHERN BELIZE TO EASTERN YUCATAN. OTHER ACTIVITY IS EXPECTED ACROSS WESTERN CUBA...WITH MOST INTENSE EXPECTED BETWEEN CIUDAD HABANA-PINAR DEL RIO AND ISLA DE LA JUVENTUD...WITH ACCUMULATION OF 75-150MM/DAY AND MAXIMA OF 250-350MM/DAY. IN THIS AREA CONSIDER POSSIBILITY OF STRONG MECHANICAL FORCING AS THE TROPICAL CYCLONE STARTS TO INTERACT WITH THE AFOREMENTIONED SURFACE FRONT OVER THE ISLAND. ALTHOUGH SOME OF THE MODELS FORECAST THE FRONT TO RETROGRESS UNDER INFLUENCE OF THE STORM...ENOUGH MECHANICAL FORCING MIGHT REMAIN TO RESULT IN EXCESSIVE RAINFALL AMOUNTS. IN NEARLY IDEAL CONDITIONS...AND AS A WORST CASE SCENARIO...THE MAXIMA IN THIS AREA COULD PEAK AT 500-750MM. FARTHER SOUTH...OVER THE EASTERN PACIFIC...A LOW ALONG THE ITCZ NEAR 12N 92W CONTINUES TO FAVOR MOISTURE ADVECTION INTO SOUTHERN GUATEMALA-EL SALVADOR/SOUTHERN HONDURAS AND WESTERN NICARAGUA. MODELS ARE HAVING A HARD TIME DEALING WITH THIS LOW...AND THEY FAIL TO MAINTAIN CONTINUITY WITH PREVIOUS FORECASTS. WE...HOWEVER...STILL BELIEVE THAT AS TD IDA STRENGTHENS OVER THE WESTERN CARIBBEAN...IT IS GOING TO DRAW THE EASTERN PACIFIC LOW TO THE NORTHEAST ACROSS EL SALVADOR/SOUTHERN HONDURAS BY 36-48 HRS. INITIALLY EXPECT RAINFALL AMOUNTS OF 10-20MM/DAY AND MAXIMA OF 40-60MM. THROUGH 48 HRS THIS WILL INCREASE TO 15-25MM/DAY AND MAXIMA OF 40-70MM. THE MOST INTENSE IS TO CONCENTRATE OVER GULF OF FONSECA REGION/TEGUCIGALPA...WITH MAXIMA TO PEAK AROUND 100MM. AS THE TROPICAL CYCLONES MODULATE THE EASTERN PACIFIC ITCZ...CONVECTION ACROSS SOUTHERN CENTRAL AMERICA IS TO REMAIN GENERALLY SPARSE WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM. ACROSS THE ABC ISLANDS...LA GUAJIRA PENINSULA/NORTHWEST VENEZUELA-NORTHERN COLOMBIA/EJE CAFETERO/THE DARIEN IN EASTERN PANAMA...EXPECT ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM IN A DIURNAL PATTERN. LOCALLY HIGHER AMOUNTS ARE EXPECTED ACROSS EJE CAFETERO/ SANTANDERES COLOMBIA-LAKE MARACAIBO REGION...WHERE THE DAILY MAXIMA COULD PEAK AT 25-50MM/DAY. OTHER LOCALIZED MAXIMUM ARE EXPECTED ALONG THE PACIFIC COAST OF COLOMBIA BETWEEN CHOCO AND VALLE DEL CAUCA. A TUTT TO THE EAST OF THE ISLANDS AND NORTH OF THE GUIANAS IS TO PERSIST DURING THE NEXT 48 HRS...THEN START TO WEAKEN BY 60-72 HRS AS THE POLAR TROUGH PATTERN NORTH OF THE ISLANDS INTENSIFIES. BY THE END OF THE CYCLE THE TUTT WILL SHEAR TO THE EAST-NORTHEAST. MOST ACTIVE CONVECTION WITH THIS FEATURE IS DEVELOPING TO THE EAST OF 45W AS IT ENHANCES ITCZ RELATED CONVECTION OVER THE TROPICAL ATLANTIC. OVER THE SOUTHERN WINDWARD ISLANDS/ORINOCO DELTA REGION ITCZ RELATED CONVECTION WILL RANGE BETWEEN 05-10MM/DAY...WITH WIDELY ISOLATED MAXIMA OF 15-25MM/DAY. PUERTO RICO AND THE USVI: AS A SUBSIDENCE PATTERN ESTABLISHES AT UPPER LEVELS...WE EXPECT A RELATIVELY DRY AND STABLE PATTERN TO ESTABLISH INTO THE WEEKEND. A SLIGHT INCREASE IN ACTIVITY IS POSSIBLE UNDER INFLUENCE OF THE FRONTAL SHEAR LINE...BUT MOST ACTIVE IS GOING TO BE ACROSS THE WESTERN/INTERIOR PORTIONS OF THE ISLAND. ON SUNDAY TO MONDAY...AS THE SURFACE FRONT APPROACHES...AND THE MID/UPPER TROUGH DEEPENS...CONDITIONS WILL BECOME MORE FAVORABLE FOR ORGANIZED CONVECTION TO DEVELOP...SO THE GENERAL TREND IS FOR HIGHER RAINFALL AMOUNTS. INVERTED TROUGHS IN THE EASTERLIES (INITIALIZED AT 12Z) INITIAL F24 F36 F48 F60 F72 F84 NONE CANALES...SMN (HONDURAS) DAVISON...NCEP (USA) $$