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Tropical Discussion
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
215 PM EST THU JAN 22 2015

DISCUSSION FROM JANUARY 22/00UTC: DEEP POLAR TROUGH PULLS ACROSS
THE SOUTHWEST TO THE CENTRAL USA THROUGH FRIDAY MORNING...AND
CONTINUES EAST ACROSS THE MISSISSIPPI VALLEY LATER ON FRIDAY.
THROUGH SATURDAY EVENING IT IS TO LIFT ACROSS THE EASTERN USA TO
THE WESTERN ATLANTIC. AS IT SURGES ACROSS NORTH AMERICA...THE
TROUGH ALOFT IS TO INTERACT WITH A SURFACE FRONT OVER THE NORTHERN
GULF. LATER TODAY IT IS TO TRIGGER CYCLOGENESIS OVER THE NORTHWEST
GULF. THIS LOW IS THEN FORECAST TO DEEPEN/INTENSIFY AT A FAIRLY
FAST PACE...SUSTAINING A NORTHERLY WIND SURGE OF 25-35KT ACROSS
THE WESTERN GULF TO THE SOUTHERN STATES OF MEXICO. THE ASSOCIATED
FRONT SURGES ACROSS TAMAULIPAS TO NORTHERN VERACRUZ EARLY ON
FRIDAY...MOVING TO SOUTHERN  VERACRUZ LATER IN THE DAY. ON
SATURDAY MORNING THE FRONT IS TO EXTEND ACROSS SOUTH FLORIDA-THE
YUCATAN TO SOUTHERN VERACRUZ...AND SATURDAY EVENING IT MOVES TO
THE NORTHWEST BAHAMAS-WESTERN CUBA-BELIZE TO SOUTHERN MEXICO.
EARLY ON SUNDAY MORNING THE FRONT CONTINUES INTO THE CENTRAL
BAHAMAS-CENTRAL CUBA TO THE GULF OF HONDURAS/BELIZE...AND BY THE
EVENING HOURS IT IS TO MOVE ACROSS THE SOUTHEAST BAHAMAS-EASTERN
CUBA TO BELIZE/NORTHWEST CARIBBEAN. ACROSS NORTHEAST MEXICO
PREFRONTAL CONVECTION IS TO RESULT IN RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM. AS IT SURGES ACROSS VERACRUZ ON
FRIDAY IT WILL SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM. MOST INTENSE IS EXPECTED ACROSS SOUTHERN
VERACRUZ-CHIAPAS-TABASCO...WHERE THE FRONT AND STRONG FRONTAL
NORTHERLIES ARE TO RESULT IN RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 35-70MM. THROUGH SUNDAY MORNING CONVECTION BUILDS EAST
ACROSS GUATEMALA TO NORTHWEST HONDURAS...WHERE WE EXPECT RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM. AS IT ENTERS THE
NORTHWEST BAHAMAS EXPECTING RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM...WHILE OVER WESTERN-CENTRAL CUBA EXPECTING
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM.

A PREFRONTAL SHEAR LINE IS TO THEN DEVELOP AHEAD OF THE SURFACE
FRONT...TO EXTEND ACROSS THE CAYMAN ISLES TO NORTHEAST NICARAGUA
LATER ON SATURDAY. THROUGH SUNDAY MORNING IT IS TO MOVE ACROSS
EASTERN CUBA/JAMAICA TO SOUTHERN NICARAGUA. ALONG THIS AXIS
EXPECTING SCATTERED SHOWERS TO DEVELOP...WITH RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM. MOST ACTIVE IS EXPECTED ACROSS
JAMAICA AND NORTHEAST HONDURAS/NICARAGUA.

BROAD MID/UPPER LEVEL RIDGE DOMINATES THE CARIBBEAN BASIN-CENTRAL
AMERICA AND THE NORTHERN PORTIONS OF SOUTH AMERICA. AT 500 HPA THE
RIDGE IS TO EXTEND WEST-TO-EAST ACROSS THE BASIN WHILE ANCHORING
ON A CLOSED HIGH OVER THE NORTHWEST CARIBBEAN. THIS PATTERN IS TO
HOLD NEARLY UNCHANGED THROUGH SATURDAY EVENING...WITH
AFOREMENTIONED POLAR TROUGH TO LIFT OVER THIS AXIS AS IT STREAMS
ACROSS NORTH AMERICA. BUT EARLY ON SUNDAY IT WILL START TO CRUMBLE
AS A DEEPER POLAR TROUGH MOVES ACROSS THE CENTRAL-EASTERN USA.
PERSISTENT RIDGE PATTERN...MEANWHILE...IS TO HELP SUSTAIN TRADE
WINDS CAP INVERSION ACROSS MOST OF THE CARIBBEAN. AT LOW
LEVELS...WANING CELL OF THE SUBTROPICAL RIDGE EXTENDS ACROSS THE
GULF OF MEXICO TO THE WESTERN ATLANTIC/NORTH OF THE ISLANDS WHILE
ANCHORING ON A CLOSED HIGH OVER EASTERN FLORIDA. UNDER PRESSURE
FROM POLAR FRONT...THIS IS TO WEAKEN/NEARLY COLLAPSE THROUGH
SATURDAY EVENING. WEAK RIDGE PATTERN TO THE NORTH TRANSLATES TO
LIGHT EASTERLY TRADES ACROSS THE BASIN. THESE WINDS ARE TO
CONVERGE OVER EASTERN NICARAGUA/NORTHEAST HONDURAS AND QUINTANA
ROO IN THE YUCATAN...WHERE THEY ARE TO FAVOR LIGHT CONVECTION WITH
ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM.

SOUTH OF THIS RIDGE...THE EASTERN PACIFIC ITCZ EXTENDS EAST ALONG
06N/07N TO NORTHWEST COLOMBIA. WEAK EASTERLY TRADES ACROSS THE
BASIN FAVOR A SOMEWHAT STRONGER THAN NORMAL PANAMANIAN LOW TO THE
WEST. THIS IS ENHANCING MOISTURE CONVERGENCE ON THE OFFSHORE
WATERS OF COLOMBIA-SOUTHERN PANAMA. ACROSS PANAMA EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM THROUGH
FRIDAY EVENING...AND 00-05MM/DAY AND MAXIMA OF 10MM THEREAFTER.
OVER WESTERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-30MM ON THE ANDEAN REGION/WESTERN PLAINS. THROUGH
FRIDAY EVENING THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF
15-20MM. OVER NORTHERN COLOMBIA AND NORTHEAST VENEZUELA EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THROUGH
SUNDAY THE MAXIMA DECREASES TO 15MM/DAY.

OVER THE TROPICAL ATLANTIC...MEANWHILE...THE ITCZ ENTERS THE
CONTINENT OVER AMAPA IN BRASIL. IT THEN LIES JUST SOUTH OF THE
EQUATOR INTO NORTHERN BRASIL. BOUNDARY IS TO REMAIN NEARLY
STATIONARY OVER THE NEXT FEW DAYS. MOST ACTIVE CONVECTION IS
EXPECTED ACROSS FRENCH GUIANA TO SURINAME...WHERE DIURNAL
CONVECTION IS TO TRIGGER RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM. THROUGH SUNDAY DAILY MAXIMA DECREASES TO 15MM.
ACROSS GUYANA AND THE SOUTHERN WINDWARD ISLANDS EXPECTING LESSER
AMOUNTS DUE TO TRADE WIND SHOWERS/SEA BREEZE CONVERGENCE...WITH
ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM. ALONG THE NEAR
EQUATORIAL TROUGH TO THE WEST...DAILY MAXIMA OVER SOUTHERN
VENEZUELA-AMAZONIA IN COLOMBIA IS TO PEAK AT 20-45MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
65W      68W    71W    74W    77W    79W    81W    DISS    EW

AN INVERTED TROUGH IN THE EASTERLY TRADES IS INITIALIZED ALONG
65W. THIS IS ENHANCING MOISTURE CONVERGENCE ACROSS THE NORTHERN VI
TO PUERTO RICO...WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-25MM. MOST INTENSE IS EXPECTED ACROSS PUERTO
RICO. ACROSS HISPANIOLA THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM...WHILE OVER NORTHWEST
VENEZUELA/NORTHERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM. LATER IN THE CYCLE IT IS TO
NEAR JAMAICA WHERE WE EXPECT RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM.

JN BAPTISTE...MS (SAINT LUCIA)
NANDA...MDS (SURINAME)
DAVISON...WPC (USA)