048  
FXCA20 KWBC 081931  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
231 PM EST WED NOV 08 2017  
 
TROPICAL DISCUSSION FROM NOV 08/12 UTC: A POLAR TROUGH MOVES  
ACROSS THE CENTRAL USA TO TEXAS EARLY IN THE CYCLE...AND THROUGH  
THURSDAY AFTERNOON IT IS TO MIGRATE ACROSS THE EASTERN USA TO THE  
WESTERN ATLANTIC...WHERE IT IS FORECAST TO LIFT OVER A RIDGE TO  
THE EAST. THIS SUSTAINS A SURFACE FRONT ACROSS TEXAS. THE FRONT  
MOVES TO NORTHEAST MEXICO LATER TODAY/EARLY THURSDAY MORNING. ON  
THURSDAY-FRIDAY THE FRONT IS TO MEANDER ACROSS THE SOUTHEAST USA  
TO NORTHERN FLORIDA/NORTHERN GULF...WHILE TRAILING END REMAINS  
OVER NORTHEAST MEXICO/SOUTH TEXAS. ON FRIDAY...REINFORCED BY AN  
ARTIC BOUNDARY TO THE NORTH...THE FRONT SURGES ACROSS FLORIDA  
WHILE TRIGGERING A PREFRONTAL SHEAR LINE ACROSS THE BAHAMAS-CUBA  
TO THE NORTHWEST CARIBBEAN/NORTHERN HONDURAS. ACROSS THE BAHAMAS  
AND ALONG THE NORTH COAST OF CUBA...IN A COOL ADVECTIVE  
PATTERN...THIS IS TO FAVOR SCATTERED SHOWERS ON THURSDAY TO  
FRIDAY...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF  
15-20MM. ON FRIDAY CONVECTION ACROSS THE NORTHWEST BAHAMAS  
DECREASES TO 05-10MM/DAY AND MAXIMA OF 15MM...WHILE OVER CENTRAL  
AND EASTERN CUBA EXPECTING RAINFALL AMOUNTS OF 05-10MM AND MAXIMA  
OF 15-20MM. OVER VERACRUZ MEXICO...BRISK NORTHERLIES ACROSS THE  
GULF ON THURSDAY AND FRIDAY WILL SUSTAIN RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15MM. ON FRIDAY THIS INCREASES TO  
10-15MM/DAY AND MAXIMA OF 20-30MM. HIGHER AMOUNTS ARE EXPECTED  
ACROSS NORTHERN HONDURAS ON THURSDAY AND FRIDAY. ON  
THURSDAY...UNDER INFLUENCE OF THE PREFRONTAL SHEAR LINE AND BRISK  
NORTHEASTERLY WINDS EXPECTING RAINFALL AMOUNTS OF 20-30MM/DAY AND  
MAXIMA OF 50-100MM. ON FRIDAY EXPECTING ACCUMULATION OF  
15-20MM/DAY AND MAXIMA OF 35-70MMM...WHILE ON SATURDAY THE MAXIMA  
PEAKS AT 25-50MM.  
 
AS THE POLAR TROUGH AMPLIFIES ACROSS THE USA IT IS TO PRESS  
AGAINST A BROAD CELL OF THE SUBTROPICAL RIDGE TO THE SOUTH. AT 250  
HPA THE RIDGE EXTENDS EAST FROM A CLOSED HIGH OVER CENTRAL  
MEXICO...ACROSS THE GULF-FLORIDA PENINSULA TO THE WESTERN  
ATLANTIC. UNDER PRESSURE FROM THE POLAR TROUGH THE RIDGE IS TO  
GRADUALLY COLLAPSE OVER THE GULF OF MEXICO/WESTERN ATLANTIC. BY  
THE END OF THE WEEK A SHORT WAVE RIDGE WILL CONFINE TO NORTHERN  
MEXICO. EARLY IN THE CYCLE THIS IS TO SUSTAIN A TRADE WINDS CAP  
ACROSS MEXICO-NORTHERN CENTRAL AMERICA. BUT AS THE RIDGE WEAKENS  
ON THURSDAY-FRIDAY...DEEPER MOISTURE IS TO THEN POOL ALONG THE  
COAST OF VERACRUZ/SOUTHERN MEXICO AND THE WESTERN  
CARIBBEAN/NORTHERN CENTRAL AMERICA. THIS IS TO THEN FEED THE  
AFOREMENTIONED PREFRONTAL CONVECTION.  
 
EAST OF THE SUBTROPICAL RIDGE...A TUTT EXTENDS TO THE  
SOUTH-SOUTHWEST ACROSS THE SOUTHEAST BAHAMAS-EASTERN CUBA TO THE  
CENTRAL CARIBBEAN. A CELL OF THE SUBEQUATORIAL RIDGE LIES TO THE  
EAST OF THIS TROUGH...ENVELOPING NORTHERN SOUTH AMERICA/EASTERN  
CARIBBEAN. THE NORTHWEST/CENTRAL BAHAMAS-CUBA-JAMAICA AND THE  
CAYMAN ISLES REMAIN ON THE CONVERGENT SIDE OF THE UPPER LEVEL  
TROUGH. THE SOUTHEAST BAHAMAS/TURKS AND CAICOS-HISPANIOLA-PUERTO  
RICO AND THE LESSER ANTILLES ARE ON THE DIVERGENT SIDE OF THE  
UPPER LEVEL RIDGE/TROUGH. AS THE SUBTROPICAL RIDGE TO THE WEST  
WEAKENS ON THURSDAY-FRIDAY...AND THE POLAR TROUGH DEEPENS ACROSS  
THE GULF...THE TUTT ALOFT IS TO GRADUALLY FILL WHILE SHEARING  
SHORT WAVE ENERGY TO THE NORTHEAST. ALTHOUGH THE UPPER LEVEL  
TROUGH IS TO FILL...THE CORRESPONDING MID LEVEL AXIS EVOLVES INTO  
A CLOSED LOW THAT IS TO MEANDER OVER JAMAICA DURING THE NEXT FEW  
DAYS. AT LOW LEVELS THE TROUGH ALOFT SUSTAINS AN INDUCED TROUGH  
ACROSS THE CENTRAL CARIBBEAN...WITH MODELS FORECASTING AN 850 HPA  
LOW TO CLOSE OVER THE CENTRAL CARIBBEAN JUST SOUTH OF JAMAICA  
EARLY IN THE PERIOD. THE TROUGH/LOW SUSTAINS A MOIST SOUTHEASTERLY  
FLOW ACROSS THE EASTERN CARIBBEAN...WITH DEEP MOISTURE POOLING  
ACROSS HISPANIOLA-PUERTO RICO/VIRGIN ISLES AND THE TURKS AND  
CAICOS/SOUTHEAST BAHAMAS. IN THIS AREA THE PWAT CONTENT PEAKS  
AROUND 50MM. THE LOW SOUTH OF JAMAICA IS TO THEN DRAW A PLUME OF  
MOISTURE ACROSS HAITI TO JAMAICA BY MIDDAY ON THURSDAY. OVER THE  
LEEWARD ISLES...THE WANING TROUGH/RIDGE PATTERN ALOFT WILL FAVOR  
ISOLATED CONVECTION EARLY IN THE CYCLE WITH ACCUMULATION OF  
00-05MM/DAY AND MAXIMA OF 10MM. ACROSS PUERTO RICO AND THE VIRGIN  
ISLES INITIALLY EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND  
MAXIMA OF 30-60MM AS ENHANCED BY A TROPICAL WAVE TO THE SOUTH. ON  
THURSDAY THIS DECREASES TO 10-15MM/DAY AND MAXIMA OF  
20-30MM...WHILE ON FRIDAY THE MAXIMA INCREASES TO 20-40MM. OVER  
THE DOMINICAN REPUBLIC EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY  
AND MAXIMA OF 20-35MM... INCREASING TO 15-20MM/DAY AND MAXIMA OF  
25-50MM ON THURSDAY. THE MOISTURE PLUME ACROSS SOUTHERN HAITI IS  
TO THEN FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF  
20-45MM. OVER JAMAICA THE TUTT INDUCED TROUGH WILL SUSTAIN  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM ON  
THURSDAY...WHILE ON FRIDAY EXPECTING ACCUMULATION OF 15-20MM/DAY  
AND MAXIMA OF 30-60MM.  
 
FURTHERMORE...THE MID/UPPER LEVEL TROUGH OVER THE CENTRAL  
CARIBBEAN IS TO INTERACT WITH THE ITCZ OVER PANAMA/COSTA RICA AND  
THE NEAR EQUATORIAL TROUGH OVER NORTHERN COLOMBIA. ACROSS  
PANAMA-COSTA RICA INITIALLY EXPECTING RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-25MM. ON THURSDAY...IN INTERACTION  
WITH THE TUTT LOW TO THE NORTH...THIS INCREASES TO 10-15MM/DAY AND  
MAXIMA OF 20-35MM. ACROSS COLOMBIA...THE CLOSED LOW OVER THE  
CENTRAL CARIBBEAN IS TO SUSTAIN A MOIST WESTERLY FLOW ACROSS THE  
EASTERN PACIFIC. THIS IS TO CONVERGE ON THE WESTERN PLAINS/ANDEAN  
REGION TO FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF  
35-70MM. ON THURSDAY THIS DECREASES TO 15-20MM/DAY AND MAXIMA OF  
25-50MM...WHILE ON FRIDAY EXPECTING RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-30MM.  
 
MEANDERING UPPER LEVEL THE CELL OF THE SUBEQUATORIAL RIDGE OVER  
THE EASTERN CARIBBEAN/NORTHERN SOUTH AMERICA IS TO VENT NEAR  
EQUATORIAL TROUGH RELATED CONVERGENCE ACROSS VENEZUELA AND ITCZ  
RELATED CONVECTION ACROSS THE GUIANAS. ACROSS VENEZUELA EXPECTING  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ACROSS THE  
GUIANAS INITIALLY EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND  
MAXIMA OF 20-35MM. ON THURSDAY-FRIDAY THIS DECREASES TO  
05-10MM/DAY AND MAXIMA OF 15-20MM.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
44W 45W 46W 47W 48W 49W 49W 50W TUTT INDCD 20N  
51W 53W 55W 57W 60W 63W 65W 66W EW 22N  
64W 67W 69W 71W 72W 73W 74W 75W TW 19N  
74W 75W 75W 76W 77W 78W 78W 79W TUTT INDCD 21N  
 
OVER THE ATLANTIC...A TUTT ALONG 45W SUSTAINS AN INDUCED TROUGH IN  
THE LOW LEVEL EASTERLIES ALONG 44W TO 20N. THIS IS TO MEANDER WEST  
INTO NORTHERN FRENCH GUIANA LATER DURING THE WEEKEND...WHERE IN  
INTEARCTION WITH THE ITCZ THIS IS TO TRIGGER RAINFALL AMOUNTS OF  
05-10MMD/AY AND MAXIMA OF 15-20MM.  
 
AN EASTERLY WAVE IS INITIALIZED ALONG 51W AND TO THE SOUTH OF 22N.  
ACROSS THE NORTHERN GUIANAS THIS IS TO INTERACT WITH THE ITCZ TO  
FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THIS  
SPREAD ACROSS GUYANA TO EASTERN VENEZUELA EARLY ON FRIDAY. OVER  
THE WINDWARD ISLANDS THIS IS TO ONLY TRIGGER WIDELY ISOLATED  
CONVECTION...WHILE OVER THE LEEWARD ISLES IT IS TO SUSTAIN  
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. ACROSS PUERTO  
RICO-VIRGIN ISLES THIS IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY  
AND MAXIMA OF 20-40MM.  
 
TROPICAL WAVE ALONG 64W AND SOUTH OF 19N IS TO ENHANCE CONVECTION  
ACROSS PUERTO RICO EARLY IN THE CYCLE TO FAVOR RAINFALL AMOUNTS OF  
15-20MM/DAY AND MAXIMA OF 30-60MM. OVER CENTRAL VENEZUELA  
EXPECTING ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM ON  
WEDNESDAY...WITH SIMILAR AMOUNTS ACROSS WESTERN VENEZUELA/EASTERN  
COLOMBIA ON THURSDAY. ACROSS HISPANIOLA THIS IS TO THEN FAVOR  
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. ACROSS  
HAITI THIS INCREASES TO MAXIMA OF 40-80MM ON FRIDAY-SATURDAY. OVER  
EASTERN COLOMBIA/NORTHWEST VENEZUELA THIS IS TO THEN FAVOR  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.  
 
THE TUTT OVER THE CENTRAL CARIBBEAN SUSTAINS A PERTURBATION IN THE  
EASTERLY TRADES WITH AXIS NORTH ALONG 74W TO 21N. AS IT MEANDERS  
OVER THE CENTRAL CARIBBEAN THIS WILL SUSTAIN ORGANIZED CONVECTION  
ACROSS HISPANIOLA WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF  
20-45MM. OVER THE SOUTHEAST BAHAMAS AND THE TURKS THIS IS TO  
TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.  
ACROSS JAMAICA THIS IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY  
AND MAXIMA OF 20-40MM ON THURSDAY-FRIDAY. ON FRIDAY-SATURDAY  
MAXIMA INCREASES TO 30-60MM.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  
 

 
 
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