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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1958Z Dec 08, 2017)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 PM EST FRI DEC 08 2017

TROPICAL DISCUSSION FROM DEC 08/12 UTC: STRONG POLAR TROUGH
EXITING INTO THE GULF OF MEXICO HAS PRODUCED HISTORIC SNOWFALL IN
NORTHERN MEXICO. NOW...THE FOCUS FOR THE ACTIVITY IN ASSOCIATION
WITH THIS TROUGH WILL SWITCH TO AREAS IN THE SOUTHERN GULF OF
MEXICO AND IN THE NORTHWESTERN CARIBBEAN...INCLUDING CUBA AND THE
BAHAMAS. AS THE UPPER TROUGH MOVES ACROSS THE WESTERN GULF OF
MEXICO ON FRIDAY...IT WILL SUSTAIN CYCLOGENESIS. THIS WILL
CONTINUE DEVELOPING A STRONG COLD FRONT AND NORTES EVENT ACROSS
THE GULF. BY FRIDAY EVENING...THE FRONT WILL EXTEND ACROSS
TAMPA...MERIDA IN THE YUCATAN PENINSULA...AND EXTREME NORTHWESTERN
GUATEMALA. DURING THIS TIME...A PRE-FRONTAL TROUGH IS FORECAST TO
ORGANIZE ACROSS THE EASTERN YUCATAN PENINSULA INTO NORTH-CENTRAL
HONDURAS. BY SATURDAY EVENING...THE FRONT WILL CONTINUE ITS RAPID
PROGRESSION TO EXTEND ACROSS THE CENTRAL BAHAMAS...SOUTH EASTERN
CUBA...JUST EAST OF THE CAYMAN ISLANDS...EXTREME NORTHEASTERN
NICARAGUA. BY THIS TIME...A SHEAR LINE WILL ORGANIZE...TO EXTEND
ACROSS SAN ANDRES/NUEVA PROVIDENCIA IN THE WESTERN CARIBBEAN AND
INTO BOCAS DEL TORO IN PANAMA. BY SUNDAY EVENING...THE FRONT WILL
EXTEND ACROSS THE TURKS AND CAICOS...SOUTHEASTERN CUBA...WESTERN
JAMAICA...CENTRAL NICARAGUA. THE SHEAR LINE WILL EXTEND ACROSS
HAITI...INTO BOCAS DEL TORO IN PANAMA. BY MONDAY EVENING...THE
FRONT WILL STALL ACROSS THE TURKS AND CAICOS...ALMOST OVER MONTEGO
BAY...CENTRAL NICARAGUA. BY THIS PERIOD...THE SHEAR LINE WILL
START TO LOSE DEFINITION WHILE STILL ENHANCING LOW-LEVEL MOISTURE
CONVERGENCE...AS IT EXTENDS ACROSS HAITI...JUST TO THE EAST OF
JAMAICA...INTO BOCAS DEL TORO IN PANAMA.

BY FRIDAY-SATURDAY...EXPECTING AN INCREASE IN ACTIVITY IN SOUTHERN
BELIZE/NORTHWESTERN HONDURAS AND EASTERN GUATEMALA...WHERE
ENHANCED OROGRAPHIC UPLIFT AS THE NORTHERLIES ARRIVE...WILL LEAD
TO 15-20MM/DAY AND MAXIMA OF 25-50MM. OROGRAPHIC ENHANCEMENT IN
THE SOUTHERN GULF LF MEXICO WILL LEAD TO MAXIMA OF 20-35MM.
PRE-FRONTAL CONFLUENCE WILL ALSO ENHANCE ACCUMULATIONS IN WESTERN
CUBA...WHERE EXPECTING 15-30MM/DAY AND MAXIMA OF 40-80MM.
ELSEWHERE ACROSS THE YUCATAN PENINSULA/BELIZE EXPECTING MAXIMA OF
15MM. BY SATURDAY-SUNDAY...ENHANCED OROGRAPHIC UPLIFT ALONG THE
NORTHERN COAST OF HONDURAS WILL LEAD TO 75-100MM/DAY AND ISOLATED
MAXIMA OF 150-250MM. ALSO...FRONTAL AND SHEAR LINE CONVERGENCE
WILL INTERACT WITH MOISTURE POOL IN THE WESTERN CARIBBEAN...TO
SUSTAIN HEAVY RAIN FROM SAN ANDRES/NUEVA PROVIDENCIA NORTH INTO
THE CAYMAN ISLANDS/WESTERN JAMAICA AND CENTRAL CUBA. IN THESE
REGIONS...EXPECTING 15-20MM/DAY AND MAXIMA OF 35-70MM. ENHANCED
OROGRAPHIC UPLIFT IN EASTERN COSTA RICA/WESTERN PANAMA...AS SHEAR
LINE DEVELOPS AND LOW-LEVEL JET FROM THE NORTH ESTABLISHES...WILL
LEAD TO 75-100MM/DAY AND MAXIMA OF 150-250MM. BY
SUNDAY-MONDAY...LARGEST AMOUNTS ARE EXPECTED WITH THE LOW-LEVEL
JET FROM THE NORTH AND THE SHEAR LINE IN COSTA RICA...WHERE
ACCUMULATIONS WILL REACH 75-100MM/DAY AND ISOLATED MAXIMA OF
200-300MM. ENHANCED CONVECTION ALONG THE SHEAR LINE AND FRONT WILL
LEAD TO 15-20MM/DAY AND MAXIMA OF 25-50MM IN EASTERN CUBA AND
JAMAICA. AND 10-15MM/DAY AND MAXIMA OF 20-40MM ACROSS SAN ANDRES
AND NUEVA PROVIDENCIA...AND 10-15MM/DAY AND MAXIMA OF 20-35MM IN
THE TURKS AND CAICOS...AND SOUTHEASTERN BAHAMAS. BY
MONDAY-TUESDAY...LOCALLY HEAVY RAINFALL WILL CONTINUE ACROSS COSTA
RICA AND WESTERN PANAMA...YET A DECREASING TREND WILL BE IN PLACE.

OTHER SYSTEM OF INTEREST...IS WEAKENING A COLD FRONT MEANDERING
SOUTHWARD ACROSS THE EASTERN CARIBBEAN. BY FRIDAY EVENING...THE
REMNANTS OF THE FRONT WILL CROSS THE CENTRAL
ANTILLES/BARBADOS...TO PRODUCE RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM. BY SATURDAY SUNDAY...THE REMNANTS WILL REACH
NORTHERN SOUTH AMERICA...TO PRODUCE SCATTERED ACCUMULATIONS OF
05-10MM/DAY AND MAXIMA OF 15MM ACROSS NORTHERN VENEZUELA INTO
TRINIDAD AND TOBAGO. SIMILAR AMOUNTS ARE EXPECTED ON
SUNDAY-MONDAY...TO DECREASE ON MONDAY.

ELSEWHERE IN NORTHERN SOUTH AMERICA...MOST ACTIVE WILL CLUSTER IN
THE AMAZON BASIN...WHERE EXPECTING GENERALLY 10-15MM/DAY AND
MAXIMA OF 20-35MM. SIMILAR AMOUNTS ARE EXPECTED IN THE GUIANAS
EARLY IN THE CYCLE...YET A SLIGHT DECREASING TREND IS TO FOLLOW.
IN COLOMBIA...MOST ACTIVE WILL CLUSTER TO THE WEST OF THE
ANDES...WHERE EXPECTING 15-20MM/DAY AND ISOLATED MAXIMA OF
25-50MM. AS THE LLANOS DRY OUT UNDER THE INFLUENCE OF THE
LOW-LEVEL JET...EXPECTING A SEASONAL DECREASE IN ACCUMULATIONS IN
THE ANDES OF CENTRAL AND NORTHERN COLOMBIA...WHERE MAXIMA WILL BE
GENERALLY UNDER 15MM/DAY AND ISOLATED.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL  24   36   48   60   72   84   96     TYPE        SOF
37W     39W  41W  43W  46W   49W  52W  55W   TUTT INDCD   19N

A WAVE IS INITIALIZED AT 37W AND TO THE SOUTH OF 19N. THIS WAVE IS
BEING INDUCED BY A STRONG POLAR TROUGH IN THE MIDDLE OF THE NORTH
ATLANTIC. AS THE POLAR TROUGH PULLS...THE WAVE IS FORECAST TO
SLOWLY PROPAGATE WESTWARD AS AN EASTERLY WAVE. THIS SYSTEM WILL
REACH THE FORECAST AREA ONLY MONDAY...WHERE IT IS FORECAST TO
PRODUCE SLIGHT ENHANCEMENT IN CONVECTION OVER THE GUIANAS.

GORDON...NMS (BELIZE)
PECK...MS (JAMAICA)
RIVAS...SENAMHI (PERU)
DAVISON/GALVEZ...WPC (USA)