313
FXSA20 KWBC 031959
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 PM EST MON MAR 03 2025
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICA FORECAST BULLETIN 3 MAR 2025 AT 2000UTC:
IN MID - LATITUDE SOUTH AMERICA â€
IN CENTRAL ARGENTINA, AN UPPER TROUGH, LOCATED ACROSS THE CENTRAL
CHILEAN ANDES ON MONDAY AFTERNOON, WILL BEGIN TO TRAVERSE CENTRAL
ARGENTINA BY MONDAY EVENING THROUGH TUESDAY MORNING. DURING THIS
PERIOD, EXPECT AN INCREASE IN UPPER DIVERGENCE ACROSS THIS REGION.
THEREAFTER, A SERIES OF SHORTWAVE UPPER AND MID LEVEL TROUGHS WILL
MOVE ACROSS THE REGION AND SUSTAIN UPPER DIVERGENCE AND VORTICITY
ADVECTION, RESPECTIVELY, DURING THEIR PASSAGE. THIS DYNAMIC UPPER
LEVEL REGIME WILL SUPPORT MEANDERING SURFACE TROUGHS. ANOTHER
FEATURE OF INTEREST IS A VERTICALLY STACKED HIGH PRESSURE SYSTEM,
WHICH WILL CONTINUE TO ENHANCE NORTHERLY WINDS INTO CENTRAL
ARGENTINA, WHERE MOISTURE CONVERGENCE IS EXPECTED ALONG AND AHEAD
OF A MEANDERING SURFACE TROUGH. NOTE, PRECIPITABLE WATER IS ABOVE
AVERAGE AND WILL HELP FAVOR HIGHER PRECIPITATION CHANCES FOR THE
NEXT THREE DAYS. THE PERIOD OF GREATEST PRECIPITATION IMPACT IS
MONDAY MORNING THROUGH TUESDAY MORNING, WHERE EXPECT A TOTAL
PRECIPITATION MAXIMA OF 30 - 60MM TO BE ACCOMPANIED BY A SLIGHT
RISK FOR SEVERE WEATHER.
IN CHILE, STARTING TUESDAY EVENING, AN UPPER JET STREAK WILL BEGIN
TO ENTER INTO AUSTRAL CHILE, INCREASING UPPER DIVERGENCE ACROSS
THE REGION THROUGH TUESDAY EVENING. DURING THIS SAME PERIOD, IN
THE LOW LEVELS, A STRONG OCCLUDED LOW PRESSURE SYSTEM WILL ALSO
HELP SUSTAIN STRONG 850 HPA WIND SPEEDS THAT ARE ACCOMPANIED BY A
LONG FETCH MOISTURE PLUME. THESE CONDITIONS WILL FAVOR MOISTURE
CONVERGENCE AND OROGRAPHIC EFFECTS ACROSS THIS REGION. THIS
MOISTURE PLUME WILL QUICKLY MOVE NORTHWARD, AND EXPECT A
SIGNIFICANT DECREASE IN 850 HPA WIND SPEEDS BY TUESDAY AFTERNOON.
THUS, THE PERIOD OF GREATEST PRECIPITATION IMPACT WILL BE MONDAY
MORNING THROUGH TUESDAY MORNING, WHERE A TOTAL PRECIPITATION
MAXIMA OF 20 - 35MM IS POSSIBLE IN SOUTH AUSTRAL CHILE.
THEREAFTER, ANOTHER LONG FETCH MOISTURE PLUME WILL BEGIN TO IMPACT
CENTRAL CHILE STARTING WEDNESDAY MORNING THROUGH THURSDAY MORNING,
FAVORING A TOTAL PRECIPITATION MAXIMA OF 15 - 20MM ACROSS CENTRAL
CHILE.
IN TROPICAL SOUTH AMERICAâ€
AN UPPER LEVEL TROUGH, WITH AN AXIS AT 19S 57W ON MONDAY
AFTERNOON, WILL BEGIN TO LOSE DEFINITION STARTING TUESDAY
AFTERNOON. ANOTHER FEATURE OF INTEREST IS A BROAD UPPER RIDGE
EXTENDING ACROSS WEST BOLIVIA AND SOUTH PERU. THESE TWO FEATURES
WILL CONTINUE TO FAVOR UPPER DIFFLUENCE AND SPEED DIVERGENCE
ACROSS CENTRAL BOLIVIA. IN THE NORTHERN PERIPHERY OF THE UPPER
RIDGE, EASTERLY WINDS WILL CONTINUE TO DOMINATE THROUGH THE
FORECAST CYCLE, FAVORING UPPER DIFFLUENCE AND DIVERGENCE IN
ECUADOR AND NORTH PERU. IN THIS REGION, IN THE LOWER LEVELS, THE
WIND FLOW DIRECTION WILL BECOME MORE WESTERLY AFTER TUESDAY
AFTERNOON, YIELDING TO AN INCREASE IN MOISTURE CONVERGENCE AND
OROGRAPHIC EFFECTS. EXPECT THE GREATEST PRECIPITATION IMPACT TO BE
FROM WEDNESDAY MORNING THROUGH THURSDAY MORNINGWHERE A A TOTAL
PRECIPITATION MAXIMA OF 30 - 60MM IS LIKELY.
ANOTHER REGION OF INTEREST IS NORTH - CENTRAL BOLIVIA, WHERE THE
UPPER LEVEL REGIME WILL FAVOR DIVERGENCE THROUGH THE FORECAST
CYCLE. IN THE LOWER LEVELS, PERSISTENT MOISTURE ADVECTION WILL
FAVOR AN INCREASE IN MOISTURE CONVERGENCE AND OROGRAPHIC EFFECTS
ACROSS THIS REGION, WHERE EXPECT A DAILY TOTAL PRECIPITATION
MAXIMA OF 20 - 35MM FOR THE NEXT THREE DAYS.
ELSEWHERE IN TROPICAL SOUTH AMERICA, THE ITCZ AND NET WILL
CONTINUE TO FAVOR DIURNAL CONVECTION. NOTE, THE ITCZ HAS BECOME
DISORGANIZED ACROSS THE PACIFIC BASIN. ELSEWHERE, A SERIES OF LOW
LEVEL TROUGHS WILL PROPAGATE ACROSS THE REGION AND WILL BE
ACCOMPANIED BY MOISTURE CONVERGENCE, HELPING YIELD TO HIGHER TOTAL
PRECIPITATION MAXIMA ACROSS THE AMAZON BASIN. IN NORTHEAST BRASIL,
THE ITCZ AND LOW LEVEL TROUGHS WILL CONTINUE TO FAVOR HIGHER TOTAL
PRECIPITATION TOTALS FOR THE FORECAST CYCLE.
MORALES...(WPC)
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