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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1159Z Aug 01, 2022)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
759 AM EDT MON AUG 01 2022

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM AUG
01/12UTC: A STRONG TUTT EXTENDS ALONG 26N 50W TO 20N 60W. THIS
ASSOCIATES WITH WESTERLY FLOW IN THE UPPER TROPOSPHERE OVER THE
NORTHEAST CARIBBEAN. IN THE LOW-LEVELS...A STRONG TRADE WIND
INVERSION IS PRESENT AT 850 HPA...WHICH REFLECTS IN THE SRATIFORM
STRUCTURES OBSERVED IN TRADE WIND CONVECTION. THE MADDEN-JULIAN
OSCILLATION CONTINUES UPPER CONVERGENT OVER THE CARIBBEAN...WHICH
IS REINFORCING DRY CONDITIONS ASSOCIATED WITH THE LOW-LYING AND
STRONG CAP. THE TRADES HAVE A SLIGHT NORTHEASTERLY
COMPONENT...WHICH WILL FOCUS ISOLATED AFTERNOON CONVECTION ON
SOUTHWEST PUERTO RICO ON MONDAY. GIVEN LIMITED AMOUNTS OF
AVAILABLE MOISTURE AND THE INFLUENCE OF THE TRADE WIND
CAP...EXPECT MAXIMA GENERALLY LIMITING TO 0.5 INCHES.

THE TUTT IS FORECAST TO RETROGRADE...TO SET ITS BASE OVER THE
ISLANDS ON TUESDAY...TO EXIT INTO THE MONA PASSAGE DURING
WEDNESDAY MORNING. THIS WILL FAVOR A PEAK IN THE STRENGTH OF
AFTERNOON CONVECTION ON TUESDAY. A TUTT-INDUCED PERTURBATION IN
THE TRADES IS ALSO FORECAST TO CROSS THE ISLANDS DURING THE DAY ON
TUESDAY TO PROVIDE ADDITIONAL ENHANCEMENT. AS NORTHEASTERLY TRADES
PERSIST INTO THE EARLY AFTERNOON...EXPECT DIURNAL INSTABILITY AND
MOISTURE FLUX CONVERGENCE TO FOCUS ON SOUTHWEST PUERTO RICO.
EXPECT MAXIMA OG 1-1.5 INCHES IN THE CORDILLERA AND LESSER AMOUNTS
ON LOW-LYING AREAS. ON WEDNESDAY...A WEAKER TRADE WIND CAP WILL
FAVOR AN EARLIER ONSET OF DIURNAL CONVECTION. ENHANCED LOW-LEVEL
WIND SHEAR AND FASTER TRADES WILL HOWEVER LIMIT MAXIMA TO 0.25-0.5
INCHES IN STREAMER/WAKE CLOUD CONVECTION DOWNSTREAM FROM EL YUNQUE
AND IN WESTERN PUERTO RICO. EXPECT LESSER AMOUNTS ON THURSDAY AS
STABILITY INCREASES IN THE LOWER TROPOSPHERE AND ACCELERATED
EASTERLY TRADES MAINTAIN ENHANCED LOW-LEVEL WIND SHEAR OVER THE
ISLANDS.

A TROPOSPHERIC KELVIN WAVE IS FORECAST TO CROSS THE CARIBBEAN
DURING THE WEEKEND INTO EARLY NEXT WEEK. THE CURRENT GUIDANCE
SUGGESTS ENHANCEMENT TO CLUSTER MAINLY IN SOUTH AMERICA.
FURTHERMORE...NO SIGNIFICANT RAIN-PRODUCING SYNOPTIC FEATURES
APPEAR ON MODEL GUIDANCE IN THE TROPICAL ATLANTIC...WHICH IS
CONSISTENT WITH THE CURRENT UPPER CONVERGENT PATTERN. BASED ON
THESE FACTORS...WE DO NOT SEE ANY SIGNIFICANT RAINFALL THREAT OVER
THE REGION WITH THE WET KELVIN WAVE AT THIS TIME.

GALVEZ...WPC (USA)