984
FXSA20 KWBC 061850
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
150 PM EST THU FEB 06 2025
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 06 FEB 2025 AT 2000 UTC:
..SUMMARY
WET CONDITIONS ARE DEVELOPING IN EQUATORIAL SOUTH AMERICA DURING
THE NEXT 3 DAYS...WHERE A COMBINATION OF ENHANCED VENTILATION...
PRECIPITABLE WATER OF 50-60MM...ENHANCED LOW-LEVEL CONVERGENCE AND
AN INCREASINGLY UPPER DIVERGENT PATTERN IN THE LARGE SCALE WILL
FAVOR HEAVY RAIN PRODUCING THUNDERSTORMS ON A DAILY BASIS. THE
AREA OF INTEREST STRETCHES FROM THE AMAZON DELTA/AMAPA INTO
CENTRAL PORTIONS OF AMAZONIA.
..LARGE SCALE CONDITIONS
THE MJO CONTINUES PROPAGATING IN PHASE 6...WHICH GENERALLY
ASSOCIATES WITH ENHANCED UPPER CONVERGENCE/LESS DEEP CONVECTION
OVER THE TROPICAL AMERICAS. HOWEVER...THE LARGE SCALE UPPER FLOW
OVER SOUTH AMERICA IS BECOMING INCREASINGLY UPPER
DIVERGENT...WHICH WILL FAVOR A CONTINUED INCREASE IN THE COVERAGE
AND INTENSITY OF DEEP CONVECTION IN TROPICAL REGIONS THROUGH THE
WEEKEND.
..TROPICAL SOUTH AMERICA
EASTERN BRASIL: IN THE UPPER LEVELS THE DOMINANT FEATURE CONTINUES
TO BE THE VCAN/UPPER LOW...WHICH CENTERS OVER CENTRAL-EASTERN
BRASIL FAVORING GENERALIZED FAIR WEATHER. THE VCAN IS FORECAST TO
SLOWLY RETROGRESS INTO NORTHEAST MATO GROSSO DO SUL THROUGH SUNDAY
MORNING...TO LIMIT THE COVERAGE OF DIURNAL CONVECTION IN MOST OF
SOUTHEAST AND EASTERN BRASIL. YET..VERY ISOLATED STRONG
THUNDERSTORMS ARE POSSIBLE WITH SUCH DEFINED MID-UPPER LOW. A MUCH
WETTER PATTERN IS EXPECTED NORTH OF THE VCAN...WHERE ENHANCED
VENTILATION...COUPLED WITH HIGH VALUES OF PRECIPITABLE WATER WILL
FAVOR SCATTERED THUNDERSTORMS CAPABLE OF PRODUCING LOCALLY HEAVY
RAIN ALONG THE NORTH COAST OF BRASIL ON A DAILY BASIS. THROUGH
EARLY SUNDAY EXPECT GENERALLY DAILY MAXIMA OF 20 - 45MM FROM CEARA
INTO THE AMAZON DELTA/NORTHERN PARA. INCREASING PRECIPITABLE WATER
AND MOISTURE CONVERGENCE...HOWEVER...WILL FAVOR HIGHER AMOUNTS IN
THE AMAZON DELTA REGION/AMAPA FROM FRIDAY THROUGH SUNDAY...WHERE
EXPECT MAXIMA IN THE 25 - 70MM/DAY RANGE.
TROPICAL ANDES AND AMAZON: THE BOLIVIAN HIGH CONTINUES
DISORGANIZED... YET IT IS FORECAST TO REGAIN DEFINITION OVER NORTH
CHILE AS THE WEEKEND PROGRESSES. ALTHOUGH THIS GENERALLY LIMITS
VENTILATION IN THE AMAZON REGION...SPEED DIFFLUENCE WILL PROVIDE
VENTILATION IN MOST OF PERU/NORTH BOLIVIA AND THE WESTERN AMAZON
ON A DAILY BASIS TO SUPPORT DEEP CONVECTION. MOREOVER...INCREASING
UPPER DIFFLUENCE AND DIVERGENCE OVER THE CENTRAL AMAZON BASIN WILL
COUPLE WITH INCREASING VALUES OF PRECIPITABLE WATER TO SUSTAIN
HEAVY RAIN PRODUCING THUNDERSTORMS ON A DAILY BASIS IN NORTHWEST
BRASIL...WHERE EXPECT MAXIMA INCREASING FROM 25 - 50MM/DAY ON
THURSDAY TO 40 - 80MM/DAY BY SATURDAY. IN THE ANDES OF PERU AND
THE ALTIPLANO EXPECT SEASONAL CONVECTION ON A DAILY BASIS WITH
AMOUNTS PEAKING ALONG THE WEST MOUNTAIN RANGE.
PACIFIC BASINS OF ECUADOR/NORTHERN PERU: UPPER WESTERLIES WILL
CONTINUE TO FAVOR UPPER CONVERGENCE WHILE MID-LEVEL EASTERLIES
FAVOR WIND SHEAR IN THE MID-UPPER TROPOSPHERE...RESULTING IN
UNFAVORABLE UPPER FLOW FOR SIGNIFICANT PRECIPITATION.
NEVERTHELESS...LOW LEVEL FLOW AND MOIST PLUMES ALONG THE COAST
WILL BE FAVORABLE FOR MODERATE ACCUMULATIONS ON THURSDAY
EVENING...PRIMARILY IN WARM CONVECTION ALONG THE WESTERN SLOPES OF
THE ANDES AND INTERIOR PORTIONS OF THE COAST. THROUGH EARLY
THURSDAY EXPECT 15 - 20MM/DAY AND MAXIMA OF 25 - 50MM. THIS
DECREASES THEREAFTER WHILE THE REGION PRONE TO THE HEAVIEST
PRECIPITATION RELOCATES TO COLOMBIA.
..EXTRATROPICAL SOUTH AMERICA
SHORT WAVE PERTURBATIONS ARE FORECAST TO CROSS THE SOUTHERN CONE
TO PRODUCE CONSERVATIVE PRECIPITATION AMOUNTS. A FRONTAL WAVE
CROSSES EARLY ON FRIDAY TO FAVOR MAXIMA OF 15 - 30MM IN SOUTHERN
AYSEN/NORTHERN MAGALLANES FROM EARLY FRIDAY THROUGH EARLY
SATURDAY. THE NEXT SYSTEM ARRIVES LATE SATURDAY/EARLY SUNDAY TO
FAVOR LOCALIZED MAXIMA OF 15 - 20MM IN NORTHERN AYSEN FROM LATE
SATURDAY THROUGH SUNDAY MORNING. FURTHER NORTH...A FRONT IS
PROPAGATING NORTHWARD ACROSS RIO GRANDE DO SUL ON THURSDAY...WHICH
WILL STIMULATE THE DRYING TREND IN ARGENTINA/URUGUAY AND FAR
SOUTHERN BRASIL. ISOLATED MAXIMA OF 20 - 40MM IS EXPECTED IN
SOUTHERN PARANA-BRASIL ON FRIDAY IN ASSOCIATION WITH THIS FRONT.
GALVEZ...(WPC)
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page