Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center
 
Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1937Z Jan 20, 2015)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product


TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
237 PM EST TUE JAN 20 2015

DISCUSSION FROM JANUARY 20/00UTC: SEASONALLY DRY PATTERN TO
CONTINUE ACROSS MEXICO. CURRENT PATTERN IS CHARACTERIZED BY
WEST-NORTHWESTERLIES AND MID-LEVELS AND SHORT WAVE PERTURBATIONS
STREAMING JUST TO THE NORTH OF NORTHERN MEXICO AFFECTING MAINLY
THE UNITED STATES. THIS IS TO CHANGE AS POTENT UPPER TROUGH IN THE
SOUTHERN STREAM DEVELOPS AND ARRIVES FROM CALIFORNIA. THIS TROUGH
IS TO EXTEND ALONG THE FOUR CORNERS INTO THE ENSENADA/TIJUANA
REGION BY WEDNESDAY EVENING...AND ACROSS NEW MEXICO-BAJA
CALIFORNIA NORTE BY THURSDAY EVENING...COAHUILA/NORTHERN SINALOA
BY FRIDAY EVENING. AS TROUGH APPROACHES...IT WILL SUSTAIN THE
DEVELOPMENT OF A LOW-LEVEL TROUGH ALONG THE SIERRA MADRE ORIENTAL
BY WEDNESDAY EVENING. CYCLOGENESIS WILL THEN FOCUS OVER THE
NORTHERN GULF OF MEXICO. THIS WILL LEAD TO THE DEVELOPMENT OF A
SURFACE FRONT THAT WILL EXTEND ACROSS NORTHERN TAMAULIPAS-SOUTHERN
COAHUILA-CENTRAL CHIHUAHUA BY THURSDAY EVENING. A NORTES EVENT IS
TO RAPIDLY DEVELOP AFTERWARDS. THIS...IN CONJUNCTION WITH FRONTAL
MOISTURE CONVERGENCE WILL BRING WET PATTERN ACROSS SOUTHEASTERN
MEXICO DEVELOPING DURING FRIDAY INTO SATURDAY. ONSHORE FLOW
CONVERGENCE ACROSS THE SIERRA MADRE ORIENTAL WILL LEAD TO ISOLATED
MAXIMA OF 10MM/DAY BY WEDNESDAY INTO EARLY THURSDAY. BY THURSDAY
INTO EARLY FRIDAY EXPECTING SIMILAR AMOUNTS ACROSS THE SIERRA
MADRE ORIENTAL AND PARTS OF CENTRAL-NORTHERN MEXICO.

MID-LEVEL RIDGE IS TO CONTINUE SETTING FOOTHOLD OVER CENTRAL
AMERICA. ONLY REGION WITH THE POTENTIAL FOR ISOLATED THUNDERSTORM
DEVELOPMENT IS COSTA RICA AND EXTREME SOUTHERN NICARAGUA...DRIVEN
MAINLY BY LOCALLY ENHANCED INSTABILITY AND TRADE WIND CONVERGENCE
THROUGH EARLY WEDNESDAY. NEVERTHELESS...MODELS ARE CONFIDENT ABOUT
PANAMANIAN LOW INTENSIFYING AND DISPLACING NORTH OF ITS
CLIMATOLOGICAL POSITION. AS THIS HAPPENS...DEEP LAYER INSTABILITY
WILL LIKELY MOVE INTO PANAMA AND EXTREME SOUTHERN COSTA RICA
DURING THURSDAY INTO FRIDAY TO LEAD TO SCATTERED THUNDERSTORMS AND
MODERATE RAINFALL ACCUMULATIONS. THROUGH EARLY WEDNESDAY EXPECTING
MAXIMA OF 15-20MM/DAY ACROSS EASTERN COSTA RICA/SOUTHERN
NICARAGUA. TRADE WIND CONVERGENCE WILL PRODUCE SIMILAR AMOUNTS
ACROSS THE BOCAS DEL TORO REGION IN PANAMA. BY WEDNESDAY INTO
EARLY THURSDAY EXPECTING ACCUMULATIONS TO DECREASE TO MAXIMA OF
15MM. ACROSS EASTERN PANAMA...AMOUNTS ARE TO INCREASE TO MAXIMA OF
15-20MM/DAY AS INSTABILITY INCREASES. BY THURSDAY INTO EARLY
FRIDAY EXPECTING AN INCREASE IN THUNDERSTORM ACTIVITY ACROSS
PANAMA TO PRODUCE MAXIMA OF 15-20MM/DAY.

ACROSS NORTHWESTERN SOUTH AMERICA...UNSEASONALLY WET PATTERN
CONTINUES. ON ONE HAND...WELL ESTABLISHED PANAMANIAM-LOW TROUGH IS
ENHANCING AFTERNOON WESTERLY WIND BURSTS INTO THE FOOTHILLS OF
SOUTHWESTERN COLOMBIA/WESTERN ECUADOR ENHANCING OROGRAPHIC UPLIFT
AND THUNDERSTORM DEVELOPMENT. ON THE OTHER HAND...DEEP-LAYER
INSTABILITY REMAINS LARGE ACROSS THE SOUTHERN TIER OF COLOMBIA AND
EXTREME SOUTHERN VENEZUELA. THE LOW-LEVEL JET OF THE LLANOS IS
FORECAST TO CONTINUE HAVING ITS EXIT IN NORTHEASTERN COLOMBIA...TO
THE WELL TO THE NORTH OF ITS CLIMATOLOGICAL POSITION. THIS IS
ALLOWING FOR MOISTURE CONVERGENCE ACROSS MOST OF THE COLOMBIAN
LLANOS...WHICH IN TERM FAVORS MOISTURE ADVECTION INTO THE CENTRAL
AND SOUTHERN ANDES OF COLOMBIA BY MID-LEVEL EASTERLIES. EXPECTING
THUS A PATTERN OF SCATTERED DIURNAL CONVECTION TO CONTINUE THROUGH
THE CYCLE WITH LARGEST RAINFALL AMOUNTS ACROSS THE CHOCO/VALLE DEL
CAUCA REGION AND SOUTHERN ANTIOQUIA/EJE CAFETERO. THROUGH EARLY
WEDNESDAY...EXPECTING LARGEST AMOUNTS ACROSS THE CHOCO/VALLE DEL
CAUCA TO PRODUCE MAXIMA OF 25-50MM/DAY. ENHANCED OROGRAPHIC UPLIFT
ALONG THE EASTERN ANDEAN FOOTHILLS WILL LEAD TO MAXIMA OF
20-45MM/DAY. ACROSS INTERIOR VALLES OF COLOMBIA AND THE SOUTHERN
LLANOS/SOUTHERN VENEZUELA EXPECTING SCATTERED MAXIMA OF
15-20MM/DAY. BY WEDNESDAY INTO EARLY THURSDAY EXPECTING SCATTERED
MAXIMA OF 20-45MM/DAY ACROSS THE WESTERN THIRD OF COLOMBIA. ACROSS
THE AMAZON REGION EXPECTING MAXIMA OF 30-60MM. ACROSS THE NORTHERN
ANDES OF COLOMBIA/ANTIOQUIA EXPECTING MAXIMA OF 15-20MM/DAY. BY
THURSDAY INTO FRIDAY EXPECTING ACCUMULATIONS OF 20-30MM/DAY ACROSS
THE ANDES OF CENTRAL COLOMBIA/CHOCO AND MAXIMA OF 15-20MM/DAY
ACROSS THE NORTHERN ANTES INTO THE ANDES OF VENEZUELA.

ACROSS THE EASTERN CARIBBEAN/GUIANAS...MOST SIGNIFICANT ACTIVITY
IS TO CONFINE TO FRENCH GUIANA AND SOUTHERN/CENTRAL SURINAME AS
ITCZ CONVECTION CONTINUES LEADING TO SCATTERED DIURNAL
ACCUMULATIONS. MODELS ARE SHOWING ACTIVITY DECREASING AFTER
WEDNESDAY. ANOTHER SOURCE OF ACTIVITY WILL BE A TUTT-INDUCED WAVE
THAT IS PRESENT ACROSS THE TROPICAL ATLANTIC. THIS SYSTEM WILL
DETACH FROM THE TUTT AND PROPAGATE AS AN EASTERLY WAVE INTO THE
EASTERN CARIBBEAN/NORTHEASTERN SOUTH AMERICA. AS THE WAVE MOVES
INTO THE BASIN...EXPECTING A GRADUAL INCREASE IN ACTIVITY
ASSOCIATED WITH IT IN RESPONSE TO A WEAKENING OF THE MID-LEVEL
RIDGE PATTERN OVER THE EASTERN CARIBBEAN. THIS WILL CONCENTRATE
ENHANCED SHOWERS ACROSS THE LEEWARD ISLANDS ON WEDNESDAY INTO
THURSDAY...PUERTO RICO AND MOST OF THE LESSER ANTILLES INTO
THURSDAY-FRIDAY...AND NORTHEASTERN VENEZUELA/TRINIDAD/NORTHWESTERN
GUYANA INTO FRIDAY-SATURDAY. OTHER REGION OF INTEREST WILL BE THE
NORTHEASTERN COASTS OF HISPANIOLA AND CUBA EARLY IN THE CYCLE...AS
NORTHEASTERLY WINDS ENHANCE SHALLOW CONVECTIVE INSTABILITY AND
LEAD TO ENHANCED OROGRAPHIC UPLIFT/COASTAL CONVERGENCE. THROUGH
EARLY WEDNESDAY...EXPECTING MAXIMA OF 15-25MM/DAY ACROSS FRENCH
GUIANA/SURINAME/SOUTHERN GUIANA AS ENHANCED CONVECTION IN NORTHERN
TIER OF THE ITCZ AND SEA BREEZE FRONT INTERACT...ALLOWING FOR
SEVERAL ROUNDS OF SHOWERS. LIGHTER AMOUNTS ARE EXPECTED INTO
PUERTO RICO/DOMINICAN REPUBLIC WHERE TRADE WIND CONVERGENCE IN
NORTHEASTERN COASTS WILL LEAD TO GENERALIZED MAXIMA OF 10MM.
ISOLATED HIGHER AMOUNTS ARE EXPECTED IN THE CORDILLERAS IN
INTERACTION WITH OROGRAPHY. BY WEDNESDAY INTO EARLY THURSDAY
EXPECTING SIMILAR AMOUNTS ACROSS THE GUIANAS...WITH A SLOW
SOUTHWARD DISPLACEMENT OF MOST FREQUENT SHOWERS. A SLIGHT INCREASE
IN THE LEEWARD ISLANDS TO MAXIMA OF 15MM/DAY. BY THURSDAY INTO
EARLY FRIDAY...EXPECTING AN INCREASE TO MAXIMA OF 15MM ACROSS MOST
OF THE LEEWARD ISLANDS/PUERTO RICO AND THE USVI.

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

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