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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1911Z Feb 15, 2018)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
211 PM EST THU FEB 15 2018

TROPICAL DISCUSSION FROM FEB 15/12 UTC: TRANSIENT WET PATTERN IN
NORTHWESTERN MEXICO WILL PERSIST THROUGH THE FORECAST CYCLE UNDER
THE INFLUENCE OF AN UPPER TROUGH IN THE PACIFIC. THIS WILL PRODUCE
INTERMITTENT SHOWERS THROUGH SATURDAY IN THE NORTHERN SIERRA MADRE
OF SONORA...WHERE AMOUNTS WILL REACH 05-10MM/DAY AND MAXIMA OF
15-25MM. ELSEWHERE IN NORTHERN BAJA CALIFORNIA AND NORTHERN SONORA
EXPECTING MAXIMA UNDER 10MM/DAY.

IN THE MID-UPPER LEVELS...A ROBUST RIDGE HAS BUILT OVER THE GULF
OF MEXICO. THE RIDGE CENTERS ON HIGH THAT WILL MEANDER FROM THE
NORTHEASTERN GULF OF MEXICO TO THE BAHAMAS FROM THURSDAY TO
FRIDAY...TO REMAIN IN PLACE THROUGH SUNDAY. THE RIDGE IS EXTENSIVE
AND WILL CONTINUE EXERTING ITS INFLUENCE ACROSS MOST OF THE
NORTHWESTERN CARIBBEAN/CUBA/THE BAHAMAS/MEXICO...AND INTO THE
NORTHERN ANTILLES. TO THE SOUTH OF THE RIDGE...A TROUGH AXIS IS
FORECAST TO LINGER THROUGH THE CYCLE EXTENDING FROM THE TROPICAL
ATLANTIC INTO THE SOUTHEASTERN CARIBBEAN. MODELS CONTINUE SHOWING
AN UPPER TROUGH DIGGING FROM THE NORTH ATLANTIC BY
FRIDAY-SATURDAY. THIS WILL PUSH THE CURRENT TROUGH AXIS SOUTHWARD
INTO NORTHERN SOUTH AMERICA BY EARLY SATURDAY. THE TRADE WIND CAP
IS STRENGTHENING ACROSS THE CARIBBEAN...YET...THE MOST IMPORTANT
FACTOR LIMITING RAINFALL ACCUMULATIONS IS THE LARGE AMOUNT OF DRY
AIR ABOVE THE BOUNDARY LAYER. THIS WILL CONTINUE SUSTAINING MAXIMA
GENERALLY UNDER 10MM. EXCEPTIONS ARE PANAMA/COSTA RICA/SOUTH
EASTERN NICARAGUA. IN THESE REGIONS...MOISTURE POOL IS BUILDING.
ENHANCED TRADE WIND CONVERGENCE WILL INTERACT WITH THE MOISTURE
POOL TO SUSTAIN LOCALIZED ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA
OF 15-25MM THROUGH THE CYCLE. ALSO...CYCLONIC VORTICITY FROM THE
BASE OF THE TROUGH IN THE SOUTHERN CARIBBEAN WILL MEANDER
NORTHWESTWARD AID WITH THE ORGANIZATION OF A ZONALLY-ORIENTED
MID-LEVEL TROUGH ACROSS NORTHERN CENTRAL AMERICA BY SATURDAY. THIS
WILL BE SUFFICIENTLY WELL DEFINED TO INTERACT WITH THE LOW-LEVELS
AND AID WITH THE BUILDING OF A MOISTURE POOL AND A TROUGH IN THE
TRADES. THIS WILL LEAD TO AN ENHANCEMENT IN RAINFALL
AMOUNTS...AIDED BY TRADE WIND CONVERGENCE IN NORTHEASTERN HONDURAS
AND SOUTHERN BELIZE/CENTRAL GUATEMALA. AMOUNTS WILL INCREASE ON
SATURDAY-SUNDAY TO SUSTAIN 05-10MM/DAY AND MAXIMA OF 15-20MM. A
FURTHER INCREASE IS EXPECTED ON SUNDAY-MONDAY...AS THE TROUGH
MEANDERS INTO BELIZE/GUATEMALA.

IN SOUTH AMERICA...ELEVATED CAP CONTINUES EXTENDING ACROSS ECUADOR
AND COLOMBIA. MOISTURE POOL HAS BUILT SUFFICIENTLY TO SUSTAIN AN
INCREASE IN RAINFALL ACCUMULATIONS...AIDED BY WESTERLIES AT
LOW-LEVELS. ALTHOUGH VERY FEW STORM CELLS ARE ABLE TO BREAK THE
INVERSION...EXPECTING MODERATE RAINFALL AMOUNTS THROUGH THE CYCLE
TO CONTINUE. THROUGH EARLY FRIDAY EXPECTING 15-20MM/DAY AND MAXIMA
OF 25-50MM IN SOUTHWESTERN COLOMBIA/WESTERN ECUADOR. THIS
DECREASES SLIGHTLY ON FRIDAY TO INCREASE ONCE AGAIN BY
SATURDAY-SUNDAY...TO MAXIMA OF 20-40MM. IN THE EJE CAFETERO/VALLE
DEL CAUCA EXPECTING MAXIMA OF 15-30MM/DAY ON A DAILY BASIS. AN
INCREASE IS EXPECTED IN CENTRAL COLOMBIA/BOGOTA REGION BY
SUNDAY...WHERE EXPECTING 05-10MM/DAY AND ISOLATED MAXIMA OF
15-20MM IN THUNDERSTORMS. ALSO IN NORTHERN SOUTH
AMERICA...TRANSIENT ACTIVE PATTERN IN THE GUIANAS WILL LEAD TO
SCATTERED PRECIPITATION THROUGH THE FORECAST CYCLE.
INITIALLY...LARGEST AMOUNTS WILL BE EXPECTED IN COASTAL AREAS FROM
FRENCH GUIANA TO GUYANA/ORINOCO DELTA...TO SUSTAIN 10-15MM/DAY AND
MAXIMA OF 20-35MM. ENHANCED LOW-LEVEL SHEAR AND PLENTIFUL CLOUD
COVER WILL LIMIT ACCUMULATIONS INLAND ON THURSDAY...TO MAXIMA OF
15-20MM/DAY. WHILE UPPER VENTILATION CONTINUES UNDER TROUGH
PATTERN TO THE NORTH...CONVECTION IN THE AMAZON WILL DRIFT
NORTHWARD TO SUSTAIN AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM
BY FRIDAY-SATURDAY. BY SATURDAY-SUNDAY...AS THE UPPER TROUGH
PROPAGATES SOUTHEASTWARD AND THE CONVERGENT SIDE POSITIONS OVER
GUYANA/WESTERN SURINAME...EXPECTING A DECREASE TO 05-10MM/DAY AND
MAXIMA OF 15-20MM. ENHANCEMENT FROM THE UPPER TROUGH IN EASTERN
SURINAME/FRENCH GUIANA WILL LEAD TO 15-20MM/DAY AND MAXIMA OF
25-50MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL    24   36   48   60   72   84   96    TYPE         SOF
NONE                               

GORDON...NMS (BELIZE)
NIXON...BDM (THE BAHAMAS)
GALVEZ...WPC (USA)