149
FXCA62 TJSJ 272024
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
424 PM AST THU FEB 27 2025
SYNOPSIS
LITTLE TO NO RAIN ACTIVITY WILL PREVAIL TONIGHT AS A DRIER AIR
MASS WITH TRACES OF SAHARAN DUST PARTICLES FILTER FROM THE EAST.
MOISTURE EMBEDDED IN THE EASTERLIES WILL BRING CLOUDS AND SHOWERS
TOMORROW, MAINLY ACROSS THE WINDWARD SECTIONS IN THE US VIRGIN
ISLANDS AND PUERTO RICO. WINDS WILL PREVAIL MAINLY FROM THE EAST
TO EAST-SOUTHEAST TOMORROW, INCREASING BY THE WEEKEND. A SIMILAR
WEATHER PATTERN WILL HOLD ON SATURDAY, WITH A SOMEWHAT DRIER AIR
MASS ON SUNDAY. A MID TO UPPER-LEVEL TROUGH WILL SWING BY THE
NORTHEAST CARIBBEAN EARLY NEXT WEEK, FOLLOWED BY A SURFACE FRONTAL
BOUNDARY BY THE END OF THE NEXT-WORKWEEK.
SHORT TERM...TONIGHT THROUGH SATURDAY
VARIABLE WEATHER CONDITIONS PREVAILED THIS MORNING ACROSS THE REGION
WITH PERSISTENT SHOWER ACTIVITY AFFECTING MOSTLY THE EASTERN
MUNICIPALITIES OF PUERTO RICO AND THE NORTHERN U.S. VIRGIN ISLANDS.
DOPPLER RADAR ESTIMATED RAINFALL ACCUMULATIONS OF ABOUT 0.50 INCHES
ACROSS THE THIS REGION. AROUND MIDDAY, THE RAINFALL ACTIVITY STARTED
TO DEVELOP ALONG THE CENTRAL INTERIOR AND WESTERN PORTIONS OF PUERTO
RICO DUE TO THE COMBINATION OF DIURNAL HEATING AND LOW-LEVEL
CONVERGENCE. MAXIMUM TEMPERATURES WERE SEEN IN THE MID TO UPPER 80S
FOR MOST COASTAL AND URBAN AREAS, AND FROM THE MID TO UPPER 70S
ACROSS THE MOUNTAINS. HEAT INDICES WERE OBSERVED FROM THE UPPER 90S
TO LOW 100S, PARTICULARLY OVER THE NORTHWESTERN AND NORTHCENTRAL
PORTIONS OF PUERTO RICO.
A DRIER AIR MASS ACCOMPANIED WITH PARTICLES OF SAHARAN DUST HAS
STARTED TO FILTERED INTO THE AREA. UNDER THIS PATTERN, HAZY SKIES
AND LIMITED SHOWER ACTIVITY ARE ANTICIPATED THROUGH AT LEAST FRIDAY.
THE PRECIPITABLE WATER CONTENT (PWAT) VALUES WILL REMAIN BETWEEN
1.00 TO 1.30 INCHES THROUGH FRIDAY AFTERNOON, THEN INCREASING TO
1.70 THROUGH SATURDAY MORNING. BY FRIDAY AFTERNOON INTO SATURDAY,
WINDS WILL SHIFT FROM THE SOUTHEAST AS A FRONTAL BOUNDARY CONTINUES
TO MOVES TOWARD THE CENTRAL ATLANTIC AND A PRE-FRONTAL TROUGH STALL
OVER THE WESTERN CARIBBEAN. UNDER THIS PATTERN, PATCHES OF MOISTURE
TRAPPED IN THE LOW-TO-MID LEVELS WILL CONTINUE TO MOVE OVER THE
REGION PROMOTING SHOWERY WEATHER ACROSS THE ISLANDS. BY SATURDAY,
ANOTHER DRIER AIRMASS WITH SAHARAN DUST PARTICLES WILL FILTER INTO
THE REGION PROMOTING HAZY SKIES, STABLE CONDITIONS AND LIMITED
RAINFALL ACTIVITY THROUGH AT LEAST EARLY NEXT WEEK.
THE 925 MB TEMPERATURES WILL REMAIN ABOVE-THAN-NORMAL FOR THE NEXT FEW
DAYS. HIGHS ARE EXPECTED TO BE IN THE MID TO UPPER 80S AND LOW 90S
ALONG THE COASTAL AND URBAN AREAS, AND IN THE UPPER 70S TO LOW 80S
IN THE MOUNTAINS AND HIGHER TERRAINS.
LONG TERM...SUNDAY THROUGH THURSDAY
PREV DISCUSSION
/ISSUED 509 AM AST THU FEB 27 2025/
FOR THE NEXT WEEK, A VARIABLE WEATHER PATTERN IS FORECAST. CURRENT
MODEL GUIDANCE SUGGESTS THAT BOTH POCKETS OF MORE HUMID AND
POCKETS OF DRIER AIR WILL REACH THE REGION SUNDAY THROUGH MONDAY.
LOW SAHARAN DUST CONCENTRATIONS WILL ALSO MOVE INTO THE REGION
LATE SUNDAY INTO MONDAY, RESULTING IN HAZY SKIES. IN THE MID TO
UPPER LEVELS, A RIDGE WILL DOMINATE THROUGHOUT THE FIRST FEW DAYS,
BEFORE AN UPPER LEVEL TROUGH APPROACHES THE ISLANDS FROM THE
NORTH WEDNESDAY AND INTO THURSDAY, INCREASING INSTABILITY. A
SERIES OF SURFACE HIGHS AND FRONTAL LOWS WILL MOVE INTO THE
WESTERN TO CENTRAL ATLANTIC DURING THE PERIOD, RESULTING IN EAST-
SOUTHEAST FLOW OVER THE ISLANDS, WITH MODEL GUIDANCE SUGGESTING
MORE SOUTH-SOUTHEAST FLOW WEDNESDAY INTO THURSDAY. EAST-SOUTHEAST
FLOW WILL STEER MORE FREQUENT PATCHES OF MOISTURE INTO OUR AREA BY
TUESDAY ONWARDS. PRECIPITABLE WATER (PWAT) VALUES WILL BE ABOVE
1.5 INCHES (ABOVE NORMAL) WITH THESE MOIST PATCHES. WITH THE MORE
SOUTHERLY FLOW WEDNESDAY AND THURSDAY, CURRENT MODEL GUIDANCE
SUGGESTS PWAT VALUES INCREASING TOWARDS NEAR 2 INCHES. AVAILABLE
MOISTURE SHOULD BE CONFINED TO BELOW 700 MB, SUNDAY AND MONDAY,
GRADUALLY MOVING ABOVE IT TO AROUND 500 MB AFTERWARDS. THE
VARIABLE WEATHER PATTERN WILL INCLUDE OVERNIGHT AND EARLY MORNING
SHOWERS STEERED TOWARDS ALONG EASTERN AND SOUTHERN COASTAL
SECTIONS OF THE ISLANDS WITH AFTERNOON CONVECTION EXPECTED FOCUSED
ACROSS THE CENTRAL INTERIOR AND NORTH/NORTHWEST SECTORS OF PUERTO
RICO. WITH THE APPROACH OF AN UPPER-TROUGH AND INCREASING
MOISTURE, A BOOST IN THIS PATTERN IS FORECAST BY MIDWEEK. 925 MB
TEMPERATURES WILL BE UP TO ABOVE NORMAL VALUES DURING THE PERIOD.
AVIATION
(18Z TAFS)
VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS ALL TAF SITES THROUGH
THE FCST PERIOD. SHRA WILL CONTINUE THRU EARLY THIS EVENING OVER
WESTERN PR. BRIEF PERIODS OF REDUCED VIS AND LOW CEILINGS CAN STILL
BE ANTICIPATED, ESPECIALLY FOR TJBQ THRU 27/23Z. WINDS ARE FROM THE
E AT 12-16 KTS, WITH STRONGER GUSTS. WINDS WILL BECOME LIGHT
AND VARIABLE BELOW 10 KTS AFT 23Z.
MARINE
A PRE-FRONTAL TROUGH FROM A FRONTAL BOUNDARY NORTH OF THE REGION,
INTERACTING WITH A BROAD SURFACE HIGH PRESSURE OVER THE ATLANTIC,
WILL PROMOTE LIGHT TO MODERATE EAST TO EAST-SOUTHEAST WINDS. AS THE
SURFACE HIGH PRESSURE BUILDS ACROSS THE CENTRAL ATLANTIC THE LOCAL
PRESSURE GRADIENT WILL TIGHTEN, PROMOTING A MODERATE TO LOCALLY
FRESH EAST-SOUTHEAST WIND FLOW THROUGHOUT THE WEEKEND.
BEACH FORECAST
OCCASIONAL RIP CURRENTS WILL DEVELOP ALONG THE NORTH AND EAST
COAST OF PR, CULEBRA AND THE US VIRGIN ISLANDS, WHERE WE EXPECT A
MODERATE RISK OF RIP CURRENTS. THE INCREASING WINDS EXPECTED FOR
THE WEEKEND, WILL MAINTAIN THE MODERATE RISK OF LIFE-THREATENING
RIP CURRENTS FOR THE ISLANDS.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT TERM/AVIATION...CVB
SYNOPSIS/LONG TERM/BEACH FORECAST....CAM
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