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Tropical Discussion
 
(Latest Discussion - Issued 1743Z Apr 03, 2020)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
143 PM EDT FRI APR 03 2020

TROPICAL DISCUSSION FROM APRIL 3/18 UTC: NORTH IN THE FORECAST
AREA AND AT MID-UPPER LEVELS...A SLOW TO PROGRESS PATTERN OF
RIDGES AND TROUGHS IS EXPECTED TO PERSIST THROUGH THE CYCLE. IN
THE MID-LEVELS...RIDGE PATTERN EXTENDS OVER CENTRAL MEXICO AND
INTO THE YUCATAN PENINSULA/GULF OF HONDURAS...WHILE A TROUGH
CENTERS NEAR/WEST OF CHIAPAS IN SOUTHERN MEXICO. MODELS AGREE ON
THE TROUGH FILLING THROUGH SATURDAY...WHILE THE RIDGE STRENGTHENS
AND BECOMES THE DOMINANT FEATURE. BY SUNDAY EVENING MODELS RESOLVE
A STRONGER RIDGE CENTERING OFF THE EASTERN COAST OF THE YUCATAN
PENINSULA...BUT EXTENDING INTO CENTRAL MEXICO AND MOST OF CENTRAL
AMERICA. UNDER THE INFLUENCE OF THE RIDGE PATTERN...DIURNAL
CONVECTION BETWEEN CENTRAL MEXICO AND SOUTHERN CENTRAL AMERICA
WILL BE ISOLATED AND PRODUCE CONSERVATIVE RAINFALL AMOUNTS. AREAS
PRONE FOR AFTERNOON CONVECTION ARE EASTERN PORTIONS OF THE EJE
VOLCANICO IN MEXICO...CHIAPAS AND GUATEMALA...AND SOUTHERN COSTA
RICA. ON FRIDAY...CONVECTION WILL SUSTAIN 05-10MM/DAY AND MAXIMA
OF 15MM IN THESE AREAS EXCEPT THE EJE VOLCANICO...WHERE MAXIMA
WILL REMAIN UNDER 10MM. AFTER FRIDAY...ALL AREAS SHOULD EXPECT
05-10MM/DAY AND MAXIMA OF 15MM ON BOTH SATURDAY AND SUNDAY. NOTE
THAT VERY ISOLATED LARGER AMOUNTS ARE POSSIBLE IN STRONGEST
THUNDERSTORMS.

TO THE NORTHWEST OF THE RIDGE...SOUTHWESTERLY FLOW AT UPPER LEVELS
WILL CONTINUE ACROSS NORTHWEST MEXICO INTO THE PLAINS OF THE
UNITED STATES. EMBEDDED IN THIS FLOW...SHORT WAVE PERTURBATIONS
WILL SUSTAIN PERIODS OF ISOLATED DEEP CONVECTION IN NORTHEAST
MEXICO. THROUGH EARLY SATURDAY...EXPECTING THUNDERSTORMS IN
EASTERN COAHUILA AND NORTHERN NUEVO LEON TO PRODUCE ACCUMULATIONS
OF 05-10MM/DAY AND MAXIMA OF 15MM ON FRIDAY...WITH A MODERATE RISK
FOR SEVERITY. ON SATURDAY...THE RISK FOR SEVERITY DECREASES...YET
ACCUMULATIONS INCREASE TO 05-10MM/DAY AND MAXIMA OF 15-25MM ACROSS
NUEVO LEON AND EASTERN COAHUILA. ON SUNDAY...THIS DECREASES TO
MAXIMA OF 15MM IN NUEVO LEON AND MAXIMA UNDER 10MM IN COAHUILA.
UNDER THE INFLUENCE OF ABUNDANT MID AND HIGH CLOUDS ASSOCIATED
WITH THE SUBTROPICAL UPPER JET...LIGHT PRECIPITATION IS ALSO
EXPECTED IN THE SIERRA MADRE OCCIDENTAL OF SONORA AND IN CENTRAL
CHIHUAHUA...ESPECIALLY ON SATURDAY AND SUNDAY. THIS WILL SUSTAIN
MAXIMA WELL UNDER 10MM/DAY.

TO THE EAST AND AT MID-LEVELS...A BROAD AND SLOW-MOVING TROUGH
PATTERN EXTENDS FROM THE FLORIDA PENINSULA EAST INTO 52W AND NORTH
OF THE GREATER ANTILLES. AT LOW-LEVELS...A SURFACE FRONT IS
SLOWING DOWN AS IT PROPAGATES ACROSS THE GREATER ANTILLES. BY
FRIDAY EVENING...THE FRONT WILL ADVANCE TO EXTEND ACROSS NORTHERN
HISPANIOLA...THE WINDWARD PASSAGE...AND ALONG THE SOUTHERN COAST
OF CUBA. BY SATURDAY EVENING...THE FRONT WILL EXTEND ACROSS PUERTO
RICO...CENTRAL HISPANIOLA...ALONG THE NORTH COAST OF CUBA. BY
SUNDAY EVENING...THE FRONTAL BOUNDARY WILL EXTEND ACROSS THE
VIRGIN ISLANDS AND PUERTO RICO...CENTRAL HISPANIOLA...INTO THE
FLORIDA STRAIT AND THE NORTHERN GULF OF MEXICO. THE SYSTEM IS
FORECAST TO DEVELOP A SHEAR LINE DURING THE DAY ON SATURDAY AS
WELL...TO EXTEND ACROSS THE VIRGINS ISLANDS INTO THE CENTRAL
CARIBBEAN BY SATURDAY EVENING...AND ACROSS THE LEEWARD ISLANDS
INTO THE CENTRAL CARIBBEAN BY SUNDAY EVENING. IN TERMS OF
PRECIPITATION...FRIDAY ACTIVITY WITH THE FRONT IS EXPECTED TO PEAK
IN EXTREME SOUTHEAST CUBA...IN NORTHERN HAITI AND IN THE NORTHERN
AND CENTRAL DOMINICAN REPUBLIC...WHERE IT WILL SUSTAIN SCATTERED
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. LIGHTER AMOUNTS ARE
EXPECTED IN SOUTHERN HAITI AND THE CAYMAN ISLANDS...WHERE
PREFRONTAL CONVECTION WILL SUSTAIN MAXIMA UNDER 10MM/DAY. THE
FRONT WILL ARRIVE INTO PUERTO RICO ON SATURDAY...TO SUSTAIN
AMOUNTS OF 05-10MM/DAY MAXIMA OF 15-20MM THROUGH EARLY MONDAY.
SIMILAR AMOUNTS ARE EXPECTED IN THE DOMINICAN REPUBLIC ON
SATURDAY...DECREASING TO 05-10MM/DAY AND MAXIMA OF 15MM BY SUNDAY.
IN THE LEEWARD ISLANDS MAXIMA WILL REMAIN UNDER 10MM/DAY THROUGH
THE CYCLE.

IN NORTHERN SOUTH AMERICA...THE UPPER SUBEQUATORIAL IS FORECAST TO
BUILD WESTWARD FROM WESTERN VENEZUELA ON FRIDAY TO PANAMA BY
SUNDAY EVENING. THIS WILL DECREASE THE DRYING IMPACT OF THE UPPER
SOUTHWESTERLIES...TO SUSTAIN AN INCREASING TREND IN PRECIPITATION
IN NORTHWEST COLOMBIA INTO SUNDAY. INITIALLY...STRONGEST
CONVECTION WILL CONCENTRATE ALONG SOUTHERN VENEZUELA/EASTERN
COLOMBIA INTO THE WESTERN VENEZUELAN ORINOQUIA. THIS WILL SUSTAIN
15-20MM/DAY AND MAXIMA OF 25-50MM ON FRIDAY. DURING THIS
PERIOD...DIURNAL CONVECTION WILL SUSTAIN 05-10MM/DAY AND MAXIMA OF
15-25MM IN MOST OF CENTRAL AND NORTHERN COLOMBIA...AND INTO THE
LAKE MARACAIBO REGION. BY SATURDAY...EXPECTING 10-15MM/DAY AND
MAXIMA OF 20-35MM TO STRETCH FROM THE NORTHERN VENEZUELAN AMAZON
BASIN INTO ALL OF WESTERN VENEZUELA AND MOST OF NORTHERN AND
CENTRAL COLOMBIA. BY SUNDAY...LARGEST ACCUMULATIONS ARE EXPECTED
IN NORTHWEST COLOMBIA INCLUDING THE DARIEN AND EASTERN
PANAMA...WHERE EXPECTING 15-20MM/DAY AND MAXIMA OF 25-50MM. IN THE
LAKE MARACAIBO REGION AND THE SANTANDERES IN COLOMBIA EXPECTING
05-10MM/DAY AND MAXIMA OF 15-25MM. ENHANCED LOW-LEVEL MOISTURE
CONVERGENCE WILL TRIGGER MODERATE PRECIPITATION ALONG THE EASTERN
SLOPES OF THE ANDES/WESTERN LLANOS IN COLOMBIA TO SUSTAIN
10-15MM/DAY AND MAXIMA OF 20-40MM MAINLY ACCUMULATED ON SUNDAY
EVENING.

IN THE GUIANAS...AS TRADE WIND SURGE/EASTERLY WAVE PHASING WITH A
TROPOSPHERIC KELVIN WAVE WILL SUSTAIN ACCUMULATIONS OF 15-20MM/DAY
AND MAXIMA OF 30-60MM IN THE SOUTHERN TIER OF THE GUIANAS ON
FRIDAY. THIS PEAKS ON SATURDAY WITH MAXIMA INCREASING TO
35-70MM/DAY. BY SUNDAY...THIS DECREASES TO ACCUMULATIONS OF
10-15MM/DAY AND MAXIMA OF 20-40MM. ALSO IN NORTHEAST SOUTH
AMERICA...AS NORTHEASTERLY TRADES INCREASE IN SPEED BY
SUNDAY...THIS WILL ENHANCE LIGHT COASTAL RAIN SHOWERS FROM THE
GUIANAS INTO NORTHEAST VENEZUELA TO SUSTAIN MAXIMA UNDER 10MM/DAY.

GALVEZ/DAVISON...WPC (USA)