214  
FXCA62 TJSJ 030752  
AFDSJU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JUAN PR  
352 AM AST FRI JAN 3 2025  
   
SYNOPSIS
 
 
THE CITIZENS AND VISITORS OF PUERTO RICO AND THE U.S. VIRGIN  
ISLANDS SHOULD EXPERIENCE MOSTLY CALM WEATHER CONDITIONS TODAY AS  
A DRIER AIRMASS FILTERS ACROSS THE ISLANDS. EXPECT A CHANGE IN  
WEATHER CONDITIONS ON SATURDAY, WHEN A COLD FRONT AND THE INDUCED  
PRE FRONTAL TROUGH BRINGS AN INCREASE IN MOISTURE THROUGH AT  
LEAST LATE SUNDAY.  
 

 
   
SHORT TERM...TODAY THROUGH SUNDAY
 
 
THE MAJORITY OF THE ISLANDS OBSERVED MOSTLY CLEAR SKIES, WITH SOME  
CLOUDS MOVING OVERNIGHT. NIGHTTIME COOLING PROMOTED LOW TEMPERATURES  
IN THE LOW 70S ALONG THE COAST TO THE LOW 60S OR EVEN THE 50S ACROSS  
THE MOUNTAINS AND VALLEYS. UNDER A NORTHEASTERLY WIND FLOW, A FEW  
SHOWERS ARRIVED OVER THE WINDWARD SECTIONS OF PR, THE VIRGIN  
ISLANDS, AND THE REGIONAL WATERS.  
 
A DRY AIR MASS WITH A RIDGE ALOFT WILL PROMOTE A STABLE WEATHER  
PATTERN WITH LITTLE OR NO RAIN ACTIVITY. THE SURFACE HIGH PRESSURE  
ACROSS THE CENTRAL ATLANTIC WILL PROMOTE A NORTHEAST WIND FLOW,  
CONTINUING THE PLEASANT TEMPERATURES. THEREFORE, EXPECT A MIX OF  
SUNSHINE AND CLOUDS WITH ONE OR TWO QUICK SHOWERS, MAINLY ACROSS THE  
WINDWARD SECTIONS IN PR AND THE US VIRGIN ISLANDS.  
 
THE INTERACTION BETWEEN A COLD FRONT APPROACHING FROM THE WEST AND  
THE SURFACE HIGH PRESSURE ACROSS THE CENTRAL ATLANTIC WILL RESULT IN  
SHOWER ACTIVITY ACROSS THE LOCAL WATERS AND WINDWARD SECTIONS OF PR  
AND THE USVI LATE TONIGHT INTO EARLY SATURDAY MORNING. AS THE FRONT  
APPROACHES THE REGION, IT WILL INDUCE A PRE-FRONTAL TROUGH POOLING  
NEAR TO ABOVE NORMAL MOISTURE OVER THE ISLANDS ON SATURDAY  
AFTERNOONS AND SUNDAYS. THIS WEATHER PATTERN WILL RESULT IN AN  
UNSETTLED WEATHER PATTERN WITH SCATTERED TO NUMEROUS SHOWERS AND A  
SLIGHT TO MODERATE CHANCE OF OBSERVING ISOLATED TO SCATTERED  
THUNDERSTORMS. THEREFORE, EXPECT A SLIGHT TO MODERATE RISK OF  
FLOODING RAINS DURING THAT TIME. FROM SUNDAY EVENING ONWARD,  
CONDITIONS WILL IMPROVE WITH THE ARRIVAL OF A DRIER AIR MASS AND THE  
ESTABLISHMENT OF A RIDGE ALOFT.  
 

 
   
LONG TERM...MONDAY THROUGH FRIDAY
 
 
THE LATEST WEATHER FORECASTS SUGGEST THAT PRECIPITABLE WATER VALUES  
WILL GRADUALLY DECREASE FROM ABOVE-NORMAL LEVELS TO AROUND NORMAL BY  
MONDAY. WE EXPECT THAT THE AVAILABLE MOISTURE WILL REMAIN CONFINED  
BELOW 700MB, MEANING ANY RAINFALL THAT DEVELOPS IS UNLIKELY TO GROW  
SIGNIFICANTLY IN VERTICAL DEPTH. THIS REDUCES THE LIKELIHOOD OF  
HEAVY RAINFALL OR INTENSE THUNDERSTORMS.  
 
AS THREE KINGS DAY APPROACHES, IT IS WORTH NOTING THAT IT IS  
UNLIKELY THE DEVELOPMENT OF SIGNIFICANT DISRUPTIVE WEATHER EVENTS  
DURING THE CELEBRATIONS. ON THE MORNING OF JANUARY 6TH, BOTH  
RESIDENTS AND VISITORS IN PUERTO RICO AND THE U.S. VIRGIN ISLANDS  
CAN EXPECT SOME PASSING SHOWERS, PRIMARILY DRIVEN BY RESIDUAL  
MOISTURE FROM A RECENT COLD FRONT AND THE ASSOCIATED PRE-FRONTAL  
TROUGH THAT PASSED CLOSE TO THE REGION. COOLER TEMPERATURES ARE ALSO  
EXPECTED AS A RESULT OF THE COLD FRONT'S PASSAGE. HOWEVER,  
CONDITIONS ARE ANTICIPATED TO IMPROVE GRADUALLY THROUGHOUT THE DAY.  
LIGHT, INTERMITTENT SHOWERS MAY STILL OCCUR, CONSISTENT WITH THE  
TYPICAL TROPICAL WINTER WEATHER PATTERN AND THE AVAILABLE MOISTURE  
ACROSS THE AREA.  
 
OVERALL, WE EXPECT THIS WEATHER PATTERN, CHARACTERIZED BY SPORADIC  
SHOWERS AND SLIGHTLY COOLER TEMPERATURES, TO PERSIST ACROSS THE  
ISLANDS DURING THE LONG TERM. THE FORECAST SUGGESTS THAT PUERTO RICO  
AND THE U.S. VIRGIN ISLANDS WILL CONTINUE TO EXPERIENCE RELATIVELY  
CALM CONDITIONS WITH BRIEF EPISODES OF LIGHT PRECIPITATION, WHICH IS  
TYPICAL DURING WINTER IN THIS TROPICAL CLIMATE.  
 

 
   
AVIATION
 
 
(06Z TAFS)  
 
VFR CONDITIONS WILL PREVAIL TODAY UNDER A NORTHEAST WIND FLOW.  
EXPECT CALM TO LIGHT AND VRB WINDS THROUGH 02/13Z, THEN WINDS WILL  
RANGE BETWEEN 10 AND 15 KT WITH HIGHER GUSTS AND SEA BREEZES. LOCAL  
EFFECTS WILL PROMOTE CLOUD DEVELOPMENT AND SHRA/-SHRA ACROSS THE  
INTERIOR AND WESTERN SECTIONS AROUND 03/16-22Z.  
 

 
   
MARINE
 
 
MODERATE EAST TO NORTHEASTERLY WINDS WILL CONTINUE TO PREVAIL THIS  
WEEK UNDER THE INFLUENCE OF A SURFACE HIGH PRESSURE MOVING INTO THE  
CENTRAL ATLANTIC AND SURFACE LOW OVER THE EASTERN ATLANTIC. A COLD  
FRONT WILL APPROACH THE NORTHEAST CARIBBEAN DURING THE WEEKEND. A  
LONG PERIOD NORTHEAST SWELL WILL SPREAD ACROSS THE ATLANTIC WATERS  
AND PASSAGES FROM TODAY ONWARDS. A LARGER NORTHWEST SWELL WILL  
ARRIVE LATER ON SUNDAY AND LINGER THROUGH EARLY NEXT WEEK. HAZARDOUS  
SEAS ARE EXPECTED FROM SATURDAY THROUGH TUESDAY.  
 

 
   
BEACH FORECAST
 
 
A LONG-PERIOD NORTHEASTERLY SWELL WILL GRADUALLY SPREAD ACROSS  
THE LOCAL WATERS ON TODAY. THIS SWELL WILL INCREASE THE RISK OF  
LIFE-THREATENING RIP CURRENTS FOR THE NORTHERN AND EASTERN EXPOSED  
BEACHES OF PUERTO RICO, CULEBRA AND ST. CROIX. IN ADDITION,  
ANOTHER LONG- PERIOD NORTHWESTERLY SWELL WILL ARRIVE LATE SUNDAY  
INTO EARLY NEXT WEEK.  
 

 
   
SJU WATCHES/WARNINGS/ADVISORIES
 
 
PR...HIGH RIP CURRENT RISK THROUGH LATE SUNDAY NIGHT FOR PRZ001-002-  
005-008-012.  
 
VI...HIGH RIP CURRENT RISK THROUGH LATE SUNDAY NIGHT FOR VIZ002.  
 
AM...NONE.  

 
 

 
 
SHORT TERM/AVIATION...CAM  
LONG TERM/MARINE/BEACH FORECAST...MMC  
 
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