668
FXCA20 KWBC 171309
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
809 AM EST TUE JAN 17 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN
17/12UTC: IN THE UPPER LEVELS...A BROAD POLAR TROUGH EXTENDS OVER
THE NORTH ATLANTIC AND IS SUSTAINING A SURFACE FRONT ACROSS THE
CARIBBEAN. ON TUESDAY MORNING...THE FRONT EXTENDS ACROSS THE
LEEWARD ISLANDS INTO THE CENTRAL CARIBBEAN AND INTO SOUTHERN
CENTRAL AMERICA. THIS IS FAVORING SCATTERED SHOWERS OVER THE
LEEWARD ISLANDS...WHILE MORE STABLE CONDITIONS ARE SET OVER THE VI
AND PUERTO RICO IN ASSOCIATION WITH THE POST FRONTAL INVERSION.
SATELLITE IMAGERY SHOWS STRATUS AND STRATOCUMULUS DECKS
DISSIPATING ACROSS THE VI...AND LIGHT SHALLOW CONVECTION ALONG THE
NORTHERN COAST OF PUERTO RICO...STIMULATED BY THE
NORTH-NORTHEASTERLY TRADES.
IN THE MID-LEVELS...A RIDGE LOCATED IN THE SOUTHEAST GULF OF
MEXICO ON TUESDAY IS FORECAST TO EXPAND WESTWARD AND FORM AN
ELONGATED AXIS FROM THE YUCATAN PENINSULA INTO 25N 65W ON THURSDAY
AND FRIDAY...TO THEN ROLL EASTWARD AND CENTER OVER THE SOUTHEAST
BAHAMAS BY THE WEEKEND WHILE STRENGTHENING. ON TUESDAY...PUERTO
RICO AND THE VI WILL BE UNDER THE INFLUENCE OF THE LOW-LYING
POST-FRONTAL INVERSION...BUT AS THIS WEAKENS ON WEDNESDAY...THE
EFFECTS OF THE MID-LEVEL RIDGE ARE FORECAST TO SET IN...TO LIMIT
PRECIPITATION AMOUNTS BY MAINTAINING A TRADE WIND CAP AND
ESPECIALLY DRY MID-LEVELS ABOVE THE MARINE LAYER. THE SURFACE
FRONT IS FORECAST TO GRADUALLY WEAKEN ON TUESDAY. AS THE POLAR
HIGH ASSOCIATED WITH THE SYSTEM WEAKENS ON WEDNESDAY...THE
EASTERLY COMPONENT OF THE TRADES IS EXPECTED TO GRADUALLY
REESTABLISH...BRINGING THE MOIST PLUME ASSOCIATED WITH THE FRONT
BACK WEST INTO THE ISLANDS. THIS WILL FAVOR A PEAK IN
PRECIPITATION ON WEDNESDAY...WHEN EXPECT AMOUNTS OF 0.2-0.4 INCHES
PRIMARILY IN NORTHEAST PUERTO RICO.
ON THURSDAY AND ON...EXPECT MORE SEASONAL CONDITIONS UNDER THE
INFLUENCE OF THE MID-LEVEL RIDGE CENTERED TO THE NORTHWEST. SOME
VARIABILITY WILL BE PRESENT IN WEAK PERTURBATIONS EMBEDDED IN THE
EASTERLY TRADES THAT PROPAGATE ACROSS THE ISLANDS. ALTHOUGH THERE
IS NO SIGNIFICANT WEATHER SYSTEM ON THE LOOK...MODEL CONFIDENCE IN
RESOLVING THE STRUCTURE AND TIMING OF THE WEAK PERTURBATIONS IS
VERY LOW. GENERALLY...EXPECT LIGHT ISOLATED RAIN SHOWERS IN
EASTERN PUERTO RICO IN MORNING HOURS AND ISOLATED AFTERNOON
CONVECTION IN THE CENTRAL AND WESTERN CORDILLERA ON A DAILY BASIS.
THE LATTER WILL ACCUMULATE MAXIMA GENERALLY LIMITED TO 0.2-0.4
INCHES ON A DAILY BASIS.
GALVEZ/ACOSTA...WPC (USA)
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