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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1827Z Oct 20, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
227 PM EDT MON OCT 20 2014

DISCUSSION FROM OCTOBER 20/00UTC: NORTH OF THE DOMAIN...POLAR
TROUGH OVER WESTERN ATLANTIC IS TO LIFT AS ANOTHER TROUGH DEEPENS
TO THE WEST INTO THE EASTERN USA. THE LATTER IS TO SLOWLY PULL
ACROSS THE EASTERN SEABOARD OF THE USA THROUGH MIDDAY ON
WEDNESDAY. AT LOW LEVELS...THIS IS TO SUSTAIN A POLAR TROUGH
ACROSS THE EASTERN USA THROUGH LATE EVENING HOURS ON
WEDNESDAY/EARLY MORNING ON THURSDAY...WHILE A POLAR RIDGE MEANDERS
ACROSS THE CENTRAL USA. SURFACE FRONT...MEANWHILE...IS TO EXTEND
ACROSS FLORIDA PENINSULA/NORTHERN GULF OF MEXICO TO TEXAS.

AS THE SURFACE FRONT MEANDERS OVER THE NORTHERN GULF...MODELS
AGREE ON A LOW PRESSURE SYSTEM TO DEVELOP OVER THE CAMPECHE SOUND.
THIS IS TO THEN MEANDER OVER THE SOUTHERN GULF OF MEXICO/YUCATAN
PENINSULA THROUGH LATE EVENING ON WEDNESDAY. THIS IS TO ENHANCE
MOISTURE TRANSPORT/CONVERGENCE ALONG THE GULF COAST OF
MEXICO...BETWEEN TAMAULIPAS AND NORTHERN CHIAPAS...WHERE IT IS TO
FAVOR RAINFALL AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-125MM
THROUGH TUESDAY MORNING. ON TUESDAY TO WEDNESDAY THIS INCREASES TO
50-75MM/DAY AND MAXIMA OF 150-250MM. ON WEDNESDAY TO THURSDAY
MORNING THE MOST ACTIVE IS EXPECTED ON THE SOUTHERN STATES OF
MEXICO TO THE YUCATAN PENINSULA...WHERE THE LOW PRESSURE CENTER IS
TO SUSTAIN ORGANIZED DEEP CONVECTION WITH RAINFALL AMOUNTS OF
35-70MM/DAY AND MAXIMA OF 100-150MM. NOTE THAT STRONG
TOPOGRAPHICAL FORCING ALONG THE GULF COAST OF MEXICO MIGHT RESULT
IN LOCALIZED MAXIMA IN EXCESS OF FORECAST GUIDANCE. DEEP MOISTURE
IS TO THEN BUILD EAST INTO WESTERN PORTIONS OF CUBA DURING THE
EARLY MORNING ON WEDNESDAY...WHERE IT IS TO FAVOR RAINFALL AMOUNTS
OF 15-30MM/DAY AND MAXIMA OF 40-80MM.

FURTHERMORE...UNDER INFLUENCE OF THE SURFACE LOW OVER THE SOUTHERN
GULF...A MOIST SOUTHWESTERLY FLOW IS TO PERSIST ACROSS
GUERRERO-SOUTHERN CHIAPAS MEXICO TO NORTHERN CENTRAL AMERICA.
THIS...IN-TURN...IS TO ANCHOR THE ITCZ ALONG THE PACIFIC COAST OF
CENTRAL AMERICA. AT UPPER LEVELS...A HIGH NEAR 12N 100W IS TO
EXTEND A RIDGE ACROSS SOUTHERN MEXICO/CENTRAL AMERICA TO THE
WESTERN CARIBBEAN. AS THE RIDGE HOLDS...THIS IS TO VENT DEEP
CONVECTION ALONG THE CONVERGENCE ZONE. ON THE SOUTHERN COAST OF
MEXICO EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM/DAY THROUGH WEDNESDAY MORNING...AND 05-10MM/DAY AND MAXIMA
OF 15-20MM ON WEDNESDAY TO THURSDAY. OVER SOUTHERN GUATEMALA-EL
SALVADOR/SOUTHERN HONDURAS EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-20MM.

FARTHER SOUTH...A LOW ALONG THE ITCZ CENTERS SOUTH-SOUTHWEST OF
COSTA RICA. THIS LOW FAVORS THE NORTHWARD MODULATION OF THE
EASTERN PACIFIC ITCZ ACROSS SOUTHERN NICARAGUA/NORTHERN COSTA RICA
TO THE SOUTHERN CARIBBEAN. THROUGH TUESDAY EVENING THE LOW IS
FORECAST TO WEAKEN TO AN OPEN TROUGH. AS IT WEAKENS...THE ITCZ IS
FORECAST TO MEANDER SOUTH TOWARDS COSTA RICA-PANAMA LATER ON
WEDNESDAY. MEANWHILE...AS THE CONVERGENCE ZONE MEANDERS ACROSS
SOUTHERN NICARAGUA THIS IS TO FAVOR RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM...WHILE ACROSS PANAMA-COSTA RICA
IN A DIURNAL PATTERN EXPECTING ACCUMULATION OF 05-10MM/DAY AND
MAXIMA OF 15-20MM.

EAST OF THE RIDGE...OVER THE CARIBBEAN...A TUTT EXTENDS ACROSS THE
WINDWARD PASSAGE/HAITI TO THE GULF OF URABA. ANOTHER TUTT LIES
OVER THE EASTERN CARIBBEAN AS IT ANCHORS ON A CLOSED LOW NORTH OF
PUERTO RICO. THE LATTER IS TO WEAKEN TO AN OPEN TROUGH DURING THE
DAY TODAY...THEN LIFT TO THE EAST-NORTHEAST. THE
FORMER...MEANWHILE...IS TO INITIALLY MEANDER ACROSS
HISPANIOLA-SOUTHERN CARIBBEAN. BUT LATER ON TUESDAY...AS RIDGE
BUILDS FROM THE WEST...THE TROUGH MOVES ACROSS PUERTO RICO WHILE
TRAILING TO NORTHERN COLOMBIA. LATER ON WEDNESDAY...THE TROUGH IS
TO THEN EXTEND ALONG 20N 50W... THE FRENCH ISLES TO NORTHERN
VENEZUELA. AS THE TUTT MEANDERS ACROSS THE SOUTHERN CARIBBEAN TO
NORTHERN VENEZUELA...THIS IS TO INTERACT WITH THE EASTERN PACIFIC
ITCZ/EQUATORIAL TROUGH IN SUPPORT OF DEEP CONVECTION ACROSS
WESTERN PLAINS/ANDEAN REGION-NORTHERN COLOMBIA TO NORTHWEST
VENEZUELA... WHERE IT IS TO RESULT IN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM. THROUGH WEDNESDAY EVENING THIS
DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS
HISPANIOLA...MEANWHILE...TROUGH ALOFT IS TO ENHANCE DIURNAL
CONVECTION THROUGH MONDAY EVENING...TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM. ACROSS PUERTO RICO...THE SHORT
WAVE TROUGH/WANING TUTT LOW IS TO ENHANCE DIURNAL CONVECTION ALONG
THE CORDILLERA CENTRAL IN PUERTO RICO EARLY IN THE CYCLE TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. AS THE UPPER
TROUGH RELOCATES ACROSS PUERTO RICO DURING THE DAY ON
TUESDAY...THIS IS TO INCREASE TO 05-10MM/DAY AND MAXIMA OF
15-25MM. BUT AS AN UPPER CONVERGENT PATTERN ESTABLISHES FOLLOWING
UPPER TROUGH PASSAGE...FAIR WEATHER CONDITIONS ARE TO THEN PREVAIL
ACROSS THE NORTHEAST CARIBBEAN ISLES. THE OPPOSITE IS EXPECTED
ACROSS THE WINDWARD/FRENCH ISLES AND NORTHEAST VENEZUELA...WHERE
TROUGH ALOFT IS TO INTERACT WITH THE ATLANTIC ITCZ. THROUGH
WEDNESDAY MORNING EXPECTING A SURGE IN ACTIVITY AS A TROPICAL WAVE
ENTERS THE EASTERN CARIBBEAN...TO RESULT IN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
46W      51W    54W    57W    59W    61W    64W    66W    TW

TROPICAL WAVE ALONG 46W AND SOUTH OF 19N MOVES ACROSS THE GUIANAS
THROUGH WEDNESDAY MORNING. BEST FORCING WITH THIS FEATURE IS
EXPECTED TO THE WEST OF THE TROUGH AXIS...WITH ORGANIZED DEEP
CONVECTION TO PRECEDE WAVE PASSAGE. ACROSS THE NORTHERN GUIANAS
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.
MOST INTENSE IS EXPECTED EARLY ON WEDNESDAY MORNING AS IT ENTERS
THE WINDWARD ISLANDS/ORINOCO DELTA...WHEN IN INTERACTION WITH A
TUTT ALOFT IT IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-45MM.

JN BAPTISTE...MS (SAINT LUCIA)
MEDINA...ONAMET (REPUBLICA DOMINICANA)
DAVISON...WPC (USA)