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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1900Z Nov 20, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST THU NOV 20 2014

DISCUSSION FROM NOVEMBER 20/00UTC: DEEP POLAR TROUGH OVER NORTH
AMERICA IS TO LIFT TO THE NORTH-NORTHEAST EARLY IN THE
CYCLE...WITH ASSOCIATED FRONT FORECAST TO THEN STALL ACROSS THE
NORTHWEST BAHAMAS-SOUTH FLORIDA/KEYS INTO THE GULF OF MEXICO EARLY
IN THE CYCLE. BOUNDARY IS TO THEN REMAIN NEARLY STATIONARY THROUGH
FRIDAY EVENING...THEN START TO MEANDER NORTH AND AWAY FROM
FORECAST AREA. THE FRONT SUSTAINS A SHEAR LINE ACROSS THE CENTRAL
BAHAMAS-CENTRAL CUBA-GULF OF HONDURAS. BUT AS THE FRONT STALLS TO
THE NORTH THE SHEAR LINE WILL BECOME ILL DEFINED EARLY ON FRIDAY
MORNING. LATER IN THE DAY...AS A POLAR HIGH RELOCATES ACROSS THE
CENTRAL USA TO THE WESTERN ATLANTIC...A NEW SHEAR LINE IS TO FORM
FARTHER TO THE EAST...WITH AXIS ACROSS THE TURKS AND
CAICOS-WINDWARD PASSAGE/EASTERN CUBA. THIS MOVES TO NORTHERN
HISPANIOLA LATER ON SATURDAY...WHERE IT REMAINS WHILE GRADUALLY
WEAKENING. AS THE FRONT MEANDERS OVER THE NORTHWEST BAHAMAS IT IS
TO FAVOR MODERATE CONVECTION WITH RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-20MM. MOST ACTIVE IS EXPECTED WITH THE SHEAR LINE
TO THE SOUTH...WITH CONVECTION ACROSS NORTHWEST HONDURAS-NORTHEAST
GUATEMALA TO SUSTAIN RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
35-70MM. ACROSS BELIZE THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM. AS THE SHEAR LINE FORMS AGAIN
OVER THE TURKS IT IS TO RESULT IN RAINFALL AMOUNTS OF 00-05MM/DAY
AND MAXIMA OF 10MM. AS IT MOVES TO NORTHERN HISPANIOLA ON SATURDAY
IT IS TO THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM.

AT 250 HPA...A HIGH NEAR JAMAICA ANCHORS A RIDGE OVER THE
CENTRAL-WESTERN CARIBBEAN-CENTRAL AMERICA. A TUTT LIES TO THE
EAST...WITH AXIS SOUTH-SOUTHWEST ACROSS THE FRENCH ISLES/EASTERN
CARIBBEAN-VENEZUELA TO EASTERN COLOMBIA. UPPER LEVEL RIDGE IS TO
CONTINUE BLOCKING THE TUTT TO THE EAST... MEANWHILE FORCING THIS
AXIS TO GRADUALLY WEAKEN WHILE SLOWLY SHEARING SHORT WAVE ENERGY
TO THE SOUTH-SOUTHWEST. THE NORTHEAST CARIBBEAN ISLES ARE TO
REMAIN ON THE CONVERGENT SIDE OF THE UPPER LEVEL RIDGE...WITH
LARGE SCALE SUBSIDENCE LIKELY TO PERSIST OVER THE NEXT FEW DAYS.
BUT WHILE THE TROUGH ALOFT WEAKENS...IT IS TO MEANWHILE TRIGGER
SHALLOW CONVECTION ACROSS THE NORTHEAST CARIBBEAN ISLES...TO
ADVECT WEST ACROSS THE VIRGIN ISLES AND PUERTO RICO. ACROSS THE
LEEWARD-VIRGIN ISLES TO EASTERN PUERTO RICO THIS IS TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM THROUGH
SATURDAY MORNING. ON THE FRENCH ISLES...TUTT ALOFT IS TO INITIALLY
FAVOR SCATTERED DEEP CONVECTION WITH ACCUMULATION OF 10-15MM/DAY
AND MAXIMA OF 20-35MM THROUGH FRIDAY MORNING...DECREASING TO
05-10MM/DAY AND MAXIMA OF 15MM ON FRIDAY TO SATURDAY. THE MOST
ACTIVE CONVECTION IS TO THE SOUTH...WHERE IN INTERACTION WITH THE
ATLANTIC ITCZ THE TROUGH ALOFT IS TO FAVOR ORGANIZED CONVECTION
ACROSS THE GRENADINES-TRINIDAD/TOBAGO-NORTHEAST VENEZUELA TO
NORTHERN GUYANA...WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
20-40MM. BUT AS THE TROUGH ALOFT WEAKENS...THIS IS TO DECREASE TO
05-10MM/DAY AND MAXIMA OF 15-20MM LATER ON SATURDAY. THE FOCUS OF
THE ITCZ RELATED CONVECTION THEN SHIFTS SOUTH ACROSS GUYANA TO
SURINAME...WHERE WE EXPECT RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-40MM. NOTE THAT IN THIS AREA THE GLOBAL MODELS
CONSISTENTLY SHOW RISK OF HEAVY RAINFALL AMOUNTS LATER ON DAY
04-05. ALSO...AS THE UPPER TROUGH TRAILS ACROSS VENEZUELA TO
COLOMBIA...THIS IS TO ENHANCE CONVECTIVE DEVELOPMENT ALONG THE
NEAR EQUATORIAL TROUGH. OVER NORTHERN COLOMBIA IT IS TO FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. THROUGH
SATURDAY IT DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-20MM. ON THE
ANDEAN REGION WESTERN PLAINS OF COLOMBIA EXPECT RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-30MM.

ITCZ RELATED CONVERGENCE OVER SOUTHERN CENTRAL AMERICA IS TO
CONTINUE FAVORING SCATTERED CONVECTION ACROSS PANAMA AND COSTA
RICA. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM....DECREASING TO 00-05MM/DAY AND MAXIMA OF 10MM
LATER ON SATURDAY.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
58W     61W    64W    66W    69W     DISSIPATES           TUTT
INDCD

THE EASTERN CARIBBEAN TUTT SUSTAINS AN INDUCED/INVERTED TROUGH IN
THE EASTERLY TRADES. THIS MOVES ACROSS THE WINDWARD
ISLES/NORTHEAST VENEZUELA LATER TODAY...TO FAVOR RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-40MM. ACROSS VENEZUELA THIS IS TO
THEN INTERACT WITH THE NEAR EQUATORIAL TROUGH IN SUPPORT OF
SCATTERED CONVECTION WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA
OF 20-35MM. THIS IS TO THEN DISSIPATE AS IT MOVES INTO COLOMBIA
LATER ON SATURDAY. RESIDUAL MOISTURE IS TO THEN ADVECT ACROSS THE
CENTRAL CARIBBEAN TO NICARAGUA LATER ON DAY 04...TO RESULT IN
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.

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