038
FXCA20 KWBC 241232
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
731 AM EST TUE JAN 24 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN
24/12UTC: IN AN INCREASINGLY UPPER CONVERGENT MJO PATTERN...A
MID-LEVEL RIDGE CONTINUES STRONG COVERING MOST OF THE CARIBBEAN
BASIN. ON TUESDAY MORNING THE RIDGE CENTERS NEAR 23N 63W AND
EXTENDS INTO NORTHERN SOUTH AMERICA AND ACROSS THE WESTERN
ANTILLES INTO SOUTHERN MEXICO. THIS IS SUSTAINING A TRADE WIND CAP
THAT IS SITTING NEAR 850 HPA OVER PUERTO RICO AND THE VI. THE SAN
JUAN SOUNDING SHOWS AN IMPRESSIVE TRADE WIND CAP ACCOMPANIED BY
PLENTY OF DRY AIR ABOVE 850 HPA. SATELLITE IMAGERY CONFIRMS THE
PRESENCE OF A VERY STABLE LAYER BASED ON THE STRATIFORM STRUCTURES
IN TRADE WIND CONVECTION ACROSS THE NORTHEAST CARIBBEAN.
THE RIDGE IS FORECAST TO CONTINUE BEING THE DOMINANT FEATURE
THROUGH THE FORECAST CYCLE. IN THE LOWER LEVELS...THE TRADES ARE
FORECAST TO REMAIN FROM THE EAST EARLY IN THE CYCLE...AND BACK TO
EAST-NORTHEASTERLIES ON THURSDAY. A SHALLOW MOIST PLUME IS
EXPECTED TO CROSS THE ISLANDS ON WEDNESDAY. THIS WILL LEAD TO A
SLIGHT INCREASE IN DIURNAL CONVECTION BUT EXPECT VERY CONSERVATIVE
ACCUMULATIONS. ACCUMULATIONS ARE EXPECTED TO DECREASE ON THURSDAY
AGAIN. ON FRIDAY...A FRONTAL SHEAR LINE IS EXPECTED TO ARRIVE IN
THE ISLANDS FROM THE NORTHEAST ON FRIDAY...AND CROSS THEM ON
FRIDAY MORNING BEFORE 18UTC. THIS WILL FAVOR SCATTERED VERY LIGHT
PRECIPITATION PRIMARILY IN NORTHERN AND EASTERN PUERTO RICO.
EXPECT MAXIMA LIMITING TO 0.15-0.2 INCHES. EXPECT ALSO VERY LIGHT
ACCUMULATIONS DEVELOPING IN SOUTHWEST PUERTO RICO IN THE
AFTERNOON...PRODUCING LESSER AMOUNTS. ON SATURDAY...THE CONTINUED
COOL ADVECTIVE FLOW ASSOCIATED WITH THE NORTHEASTERLY TRADES WILL
CONTINUE TO STIMULATE LATE NIGHT/EARLY MORNING LIGHT RAIN SHOWERS
ALONG THE NORTH AND EAST COASTS OF THE ISLAND...TO PRODUCE SIMILAR
AMOUNTS. YET...THE STRENGTHENING OF THE CAP WILL LIMIT AFTERNOON
DEVELOPMENT ON SOUTHWEST PUERTO RICO.
GALVEZ/ACOSTA/ALAMO...WPC (USA)
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