716  
FXCA20 KWBC 031829  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
229 PM EDT FRI NOV 03 2017  
 
TROPICAL DISCUSSION FROM NOV 03/12 UTC: WEST OVER THE DOMAIN...A  
500/250 HPA HIGH OVER MEXICO NEAR 21N 101W EXTENDS A RIDGE NORTH  
TO THE SOUTHWEST USA...AND EAST TO NORTHERN CENTRAL AMERICA. THIS  
RIDGE IS FORECAST TO BUILD ACROSS THE GULF OF MEXICO TO THE  
SOUTHERN USA LATER ON SATURDAY...WHERE IT IS TO HOLD THROUGH AT  
LEAST MONDAY MORNING. OVER MEXICO THIS IS TO SUSTAIN A CAP  
INVERSION THAT IS TO INHIBIT ORGANIZED DEEP CONVECTION.  
 
AS THE MID/UPPER LEVEL RIDGE TO THE WEST BUILDS ACROSS MEXICO/THE  
GULF...IT IS TO STEER A SHORT WAVE TROUGH ACROSS THE GULF OF  
MEXICO. LATER TODAY THE TROUGH IS TO EXTEND FROM NORTHERN FLORIDA  
TO THE YUCATAN PENINSULA. ON SATURDAY IT PHASES WITH A SHORT WAVE  
TROUGH STREAMING TO THE NORTH...WITH THE ENSUING UPPER LEVEL  
PERTURBATION TO EXTEND ALONG THE EAST COAST OF THE USA...ACROSS  
CUBA TO BELIZE/GULF OF HONDURAS. AT 500 HPA THIS WILL BE  
ACCOMPANIED BY A STRONG CYCLONIC MAXIMA THAT MOVES ACROSS FLORIDA  
TO CUBA LATER ON SATURDAY/EARLY SUNDAY MORNING. LATER ON SUNDAY IT  
MEANDERS OVER THE BAHAMAS-CUBA-NORTHWEST CARIBBEAN. AS IT  
AMPLIFIES ACROSS THE YUCATAN THE UPPER LEVEL TROUGH IS TO ENHANCE  
CONVECTIVE DEVELOPMENT. OVER BELIZE-GUATEMALA EXPECTING RAINFALL  
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM/DAY THROUGH SATURDAY.  
ON SATURDAY-SUNDAY THIS WILL THEN ENHANCE CONVECTION ACROSS  
NORTHERN HONDURAS TO NORTHEAST NICARAGUA...WHERE IT IS TO ALSO  
TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THE  
DEEPENING MID/UPPER LEVEL TROUGH IS TO ALSO ENHANCE CONVECTION  
ACROSS CUBA AND THE BAHAMAS. OVER THE BAHAMAS INITIALLY EXPECTING  
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. THROUGH  
SATURDAY THIS INCREASES TO 05-10MM/DAY AND MAXIMA OF 15-25MM.  
ACROSS CENTRAL-EASTERN CUBA TO JAMAICA INITIALLY EXPECTING  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ON SATURDAY  
TO SUNDAY THIS INCREASE TO 10-15MM/DAY AND MAXIMA OF  
20-30MM...WHILE ON SUNDAY THE MAXIMA PEAKS AT 20-45MM.  
 
THE MID LEVEL HIGH OVER CENTRAL MEXICO ALSO EXTENDS A RIDGE ACROSS  
THE NORTHWEST CARIBBEAN TO THE GREATER ANTILLES. AS THE RIDGE  
BUILDS TO THE WEST...IT IS TO STEER SHORT WAVE PERTURBATIONS  
ACROSS THE WESTERN ATLANTIC/NORTHERN CARIBBEAN ISLES.  
THIS...IN-TURN...IS TO SUSTAIN THE GRADUAL EROSION OF THE MID  
LEVEL RIDGE PATTERN AND ASSOCIATED TRADE WINDS INVERSION OVER THE  
EASTERN CARIBBEAN ISLES LATER ON SATURDAY. IN THIS PATTERN THE  
ENVIRONMENTAL CONDITIONS ARE TO THEN REMAIN FAVORABLE FOR DEEP  
CONVECTION TO DEVELOP THROUGH THE MIDDLE OF NEXT WEEK. WEAKENING  
OF THE TRADE WINDS CAP WILL COINCIDE WITH ARRIVAL OF AN  
ATMOSPHERIC KELVIN WAVE EARLY NEXT WEEK AS INDICATED BY THE CFS  
CLIMO MODEL. THUS FAVORING A HIGHER RISK OF ORGANIZED CONVECTION  
LATER DURING THE WEEKEND/EARLY NEXT WEEK. AS THE RIDGE OVER THE  
CARIBBEAN WEAKENS...A TUTT TO THE EAST IS TO THEN LIFT TO THE  
NORTH-NORTHEAST ON SATURDAY-SUNDAY. AT LOW LEVELS THIS SUSTAINS AN  
INDUCED INVERTED TROUGH ACROSS THE LESSER ANTILLES TO THE EASTERN  
CARIBBEAN. AS THE UPPER TROUGH WEAKENS THE LOW LEVEL PERTURBATION  
IS TO THEN MEANDER WEST ACROSS THE BASIN. UNDER INFLUENCE OF THIS  
FEATURE A LONG FETCH SOUTHEASTERLY FLOW WILL ESTABLISH ACROSS THE  
ISLAND CHAIN/EASTERN CARIBBEAN. THIS WILL THEN DRAW A PLUME OF  
DEEP TROPICAL MOISTURE ACROSS THE LESSER ANTILLES TO THE VIRGIN  
ISLES ON SATURDAY...AND ACROSS PUERTO RICO ON SUNDAY. THE PWAT  
CONTENT IS TO INITIALLY PEAK AT 35-40MM...INCREASING TO 50MM EARLY  
NEXT WEEK. AS THE PATTERN CHANGES...THE GLOBAL MODELS AGREE ON  
SCATTERED DEEP CONVECTION TO BUILD ACROSS THE LESSER ANTILLES TO  
PUERTO RICO-VIRGIN ISLES DURING THE WEEKEND. THE GFS AND UKMET  
SHOW CONSIDERABLY HIGHER AMOUNTS THAN WHAT THE ECMWF PROJECTS. BUT  
UNDER INFLUENCE OF ATMOSPHERIC KELVIN WAVE IT LOOKS LIKE THE  
GFS-UKMET SOLUTION MIGHT BE THE BEST. OVER THE WINDWARD ISLANDS  
THE PLUME OF MOISTURE IS TO SUSTAIN RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-30MM. ON SATURDAY THIS IS TO SPREAD  
ACROSS THE LEEWARD-VIRGIN ISLES TO SUSTAIN RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-30MM IN DEEP CONVECTION. OVER PUERTO  
RICO AND THE DOMINICAN REPUBLIC THIS IS TO THEN TRIGGER RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM ON SUNDAY TO  
MONDAY...WITH LOCALLY HIGHER AMOUNTS ACROSS WESTERN INTERIOR  
PORTIONS OF PUERTO RICO. ACTIVITY ACROSS PUERTO RICO IS TO BECOME  
MORE ACTIVE/BETTER ORGANIZED ON MONDAY-TUESDAY.  
 
SOUTH OVER THE DOMAIN...THE EASTERN PACIFIC ITCZ MEANDERS EAST  
ACROSS SOUTHERN CENTRAL AMERICA TO NORTHERN SOUTH AMERICA. OVER  
COSTA RICA-PANAMA TO NORTHERN COLOMBIA THIS IS TO FAVOR SCATTERED  
DEEP CONVECTION WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF  
15-20MM/DAY. ON SATURDAY THIS INCREASES TO 10-15MM/DAY AND MAXIMA  
OF 20-35MM. OVER COLOMBIA...IN A DEEP LAYER WESTERLY FLOW ACROSS  
THE EASTERN PACIFIC...MOISTURE IS TO CONVERGE ALONG THE WEST  
COAST/ANDEAN REGION. EARLY IN THE CYCLE THIS IS TO FAVOR RAINFALL  
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. THROUGH SATURDAY  
THIS INCREASES TO 15-20MM/DAY AND MAXIMA OF 30-60MM. ON SUNDAY  
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.  
OVER AMAZONIA IN COLOMBIA EXPECTING RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-40MM. THROUGH SATURDAY THE DAILY  
MAXIMA INCREASES TO 25-50MM. ACROSS VENEZUELA TO GUYANA/NORTHERN  
SURINAME EXPECTING RAINFALL AMOUNTS OF 05-10MMD/AY AND MAXIMA OF  
15-20MM/DAY.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
40W 43W 46W 49W 52W 55W 58W 62W TW 14N  
64W 66W 68W 69W 70W 71W 73W 75W TUTT INDCD 21N  
69W 71W 73W 75W 77W 79W 81W 82W TUTT INDCD 18N  
 
AT 700 HPA...A TROPICAL WAVE ALONG 40W AND SOUTH OF 12N REACHES  
FRENCH GUIANA EARLY ON SUNDAY MORNING. THIS IS TO TRIGGER  
SCATTERED DEEP CONVECTION ACROSS FRENCH GUIANA TO SURINAME...WITH  
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM.  
 
THE TUTT EAST OF THE ISLANDS SUSTAINS AN INDUCED TROUGH IN THE  
EASTERLY TRADES WITH AXIS NORTH ALONG 64W TO 21N. UNDER INFLUENCE  
OF THIS FEATURE THE LOW LEVEL WINDS ARE VEERING TO THE SOUTHEAST.  
THIS...IN-TURN...IS TO DRAW A PLUME OF DEEP TROPICAL MOISTURE  
ACROSS BARBADOS AND THE WINDWARD ISLES...TO RESULT IN RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-30MM. ON SATURDAY THIS  
SPREADS ACROSS THE VIRGIN ISLES TO EASTERN PUERTO RICO TO SUSTAIN  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. OVER  
HISPANIOLA THIS IS TO THEN TRIGGER RAINFALL AMOUNTS OF 05-10MM/DAY  
AND MAXIMA OF 15-25MM. ACROSS VENEZUELA...IN INTERACTION WITH THE  
NET...EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF  
15-25MM. OVER NORTHWEST VENEZUELA TO NORTHEAST COLOMBIA THIS  
INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-35MM ON SATURDAY  
EVENING/SUNDAY MORNING.  
 
ANOTHER TUTT INDUCED TROUGH ALONG 69W TO 18N WILL MEANDER  
WEST-SOUTHWEST ACROSS THE CENTRAL CARIBBEAN. EARLY IN THE CYCLE IT  
IS TO SUSTAIN SCATTERED CONVECTION ACROSS HAITI WITH ACCUMULATION  
OF 05-10MM/DAY AND MAXIMA OF 15MM. ON SATURDAY THIS IS TO ENHANCE  
CONVECTION ACROSS NORTHWEST VENEZUELA-NORTHERN COLOMBIA TO FAVOR  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  
 

 
 
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