991
FXCA62 TJSJ 020815
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
415 AM AST MON JUN 2 2025
KEY MESSAGES
* A DENSE SAHARAN AIR LAYER WILL CONTINUE TO CAUSE HAZY SKIES.
DRY AND STABLE CONDITIONS WILL PERSIST EARLY IN THE WEEK.
* HOT TEMPERATURES ARE ANTICIPATED ONCE AGAIN TODAY. THIS LEVEL OF
HEAT AFFECTS MOST INDIVIDUALS SENSITIVE TO HEAT, ESPECIALLY
THOSE WITHOUT EFFECTIVE COOLING OR ADEQUATE HYDRATION.
SHORT TERM...TODAY THROUGH WEDNESDAY
DURING THE OVERNIGHT HOURS, A VERY STABLE WEATHER PATTERN PREVAILED
ACROSS THE REGION, WITH MOSTLY CLEAR AND HAZY SKIES DUE TO THE
ONGOING PRESENCE OF SAHARAN DUST. MINIMAL CLOUD DEVELOPMENT WAS
OBSERVED, AND NO SIGNIFICANT SHOWER ACTIVITY OCCURRED. TEMPERATURES
REMAINED SLIGHTLY ABOVE CLIMATOLOGICAL NORMALS, WITH COASTAL AREAS
GENERALLY IN THE LOW 80S, WHILE CONDITIONS WERE NOTICEABLY COOLER IN
THE HIGHER ELEVATIONS OF THE INTERIOR MOUNTAINS.
A STABLE AND DRY WEATHER PATTERN WILL CONTINUE THROUGH TUESDAY,
SUPPORTED BY A MID-LEVEL RIDGE AND THE PRESENCE OF SAHARAN DUST OVER
THE REGION. A BROAD SURFACE HIGH OVER THE CENTRAL ATLANTIC WILL
PROMOTE SOUTHEASTERLY WINDS, RESULTING IN HAZY SKIES, ABOVE-NORMAL
TEMPERATURES, AND LIMITED RAINFALL. FOR TODAY, A HEAT ADVISORY
REMAINS IN EFFECT FROM 10 AM THROUGH THE AFTERNOON AT 4 PM AST FOR
NORTHERN, WESTERN, AND SOUTHERN COASTAL AREAS OF PUERTO RICO DUE TO
WARM LOW-LEVEL TEMPERATURES AND PERSISTENT SOUTHEASTERLY WINDS.
ATMOSPHERIC MOISTURE IS RUNNING BELOW NORMAL, AND MID-LEVEL HUMIDITY
IS LIMITED, WHICH WILL INHIBIT VERTICAL CLOUD DEVELOPMENT. WHILE
OVERALL CHANCES FOR RAINFALL REMAIN LOW, BRIEF AFTERNOON SHOWERS
DRIVEN BY LOCAL EFFECTS MAY STILL OCCUR ACROSS NORTHWESTERN
SECTIONS. ON TUESDAY, THE HEAT WILL BE SLIGHTLY LESS INTENSE AS
WINDS SHIFT MORE FROM THE EAST AND AN EVEN DRIER AIR MASS MOVES IN,
WITH MOISTURE LEVELS FALLING WELL BELOW NORMAL. THIS WILL REINFORCE
STABLE CONDITIONS, RESULTING IN MINIMAL SHOWER ACTIVITY.
BY EARLY WEDNESDAY, PATCHES OF FRAGMENTED MOISTURE ARE FORECAST TO
MOVE INTO THE REGION, BRINGING A SLIGHT INCREASE IN QUICK-MOVING,
LIGHT TO MODERATE SHOWERS DURING THE MORNING HOURS. WITH SAHARAN
DUST CONCENTRATIONS DECREASING AND MOISTURE VALUES TRENDING BACK
TOWARD SEASONAL LEVELS, INSTABILITY IS EXPECTED TO IMPROVE SLIGHTLY.
THIS MAY ALLOW FOR MORE WIDESPREAD AND STRONGER AFTERNOON CONVECTION
ON WEDNESDAY, PARTICULARLY ACROSS INTERIOR AND WESTERN PUERTO RICO,
UNDER MORE FAVORABLE THERMODYNAMIC CONDITIONS COMPARED TO EARLIER IN
THE WEEK.
LONG TERM...THURSDAY THROUGH MONDAY
A MID TO UPPER LEVEL HIGH WILL MAINTAIN STABLE CONDITIONS ALOFT
THROUGH THE END OF THE WEEK. AT THE SURFACE, HIGH PRESSURE
CENTERED OVER THE EASTERN ATLANTIC WILL KEEP THE TRADE WIND
STRONG, AROUND 15 TO 20 KNOTS, OUT OF THE EAST OR SOUTHEAST.
ON THURSDAY, A WEAK TROUGH WILL SNEAK IN, THOUGH, MOSTLY WORKING
TO ENHANCE THE SHOWER ACTIVITY IN THE AFTERNOON ACROSS WESTERN
PUERTO RICO. LATER ON FRIDAY AND THE WEEKEND, THE TRADE WIND CAP
INVERSION DEVELOPS AGAIN, TRAPPING ALL THE MOISTURE TO THE LOWEST
LEVELS OF THE ATMOSPHERE. CHANCES OF SHOWERS WILL BE LIMITED TO
AFTERNOON CONVECTION ACROSS THE WEST, AND A FEW SHOWERS STREAMING
INTO THE VIRGIN ISLANDS OR EASTERN PUERTO RICO. SOME SAHARAN DUST
WILL FILTER IN TOO, ESPECIALLY BY THE END OF THE WEEK.
CONCENTRATIONS ARE NOT EXPECTED TO BE HIGH, HOWEVER. THEN, ON
MONDAY, THERE IS GOING TO BE AN INCREASE IN MOISTURE AS A TROPICAL
WAVE APPROACHES. THROUGH THE FORECAST PERIOD, TEMPERATURES WILL BE
SEASONABLY WARM, WITH HIGHS IN THE UPPER 80S AND LOW 90S, AND HEAT
INDICES JUST ABOVE 100 DEGREES FOR MOST OF THE COASTAL AND URBAN
AREAS OF THE LOCAL ISLANDS.
AVIATION
(06Z)
VFR CONDITIONS WILL PERSIST ACROSS ALL TAF SITES
DURING THE PERIOD. SAHARAN DUST PARTICLES WILL INDUCE A REDUCTION IN
VIS AND LOWER FLIGHT-LEVEL CEILINGS IN SOME AREAS. IN GENERAL, WINDS
WILL REMAIN VRB, INCREASING BY 02/15Z, BECOMING FROM THE E-SE AT 15
KNOTS WITH GUSTY WINDS. SHOWERS ARE NOT FORECAST ACROSS OR NEAR TAF
SITES.
MARINE
A SURFACE HIGH PRESSURE OVER THE ATLANTIC BASIN WILL CONTINUE TO
PROMOTE MODERATE TO LOCALLY FRESH TRADE WINDS OVER THE NEXT FEW DAYS.
SOUTHEAST WINDS WILL PREVAIL THROUGH MONDAY, BECOMING MORE EASTERLY
THROUGH THE REST OF THE WEEK. SMALL CRAFT SHOULD EXERCISE CAUTION
ACROSS PORTIONS OF THE OFFSHORE WATERS AND LOCAL CARIBBEAN PASSAGES.
HAZY SKIES AND REDUCED VISIBILITIES ARE EXPECTED TO CONTINUE THROUGH
AT LEAST TUESDAY DUE TO HIGH CONCENTRATIONS OF SAHARAN DUST OVER THE
REGION.
BEACH FORECAST
BREEZY WINDS FROM THE SOUTHEAST WILL MAINTAIN A MODERATE RIP
CURRENT RISK FOR THE SOUTHERN BEACHES OF PUERTO RICO, VIEQUES,
CULEBRA, AND SAINT CROIX THROUGH TUESDAY. THEN, THE MODERATE RIP
CURRENT RISK WILL SPREAD ALONG THE NORTH AND EASTERN BEACHES OF
PUERTO RICO AS WELL.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HEAT ADVISORY FROM 10 AM THIS MORNING TO 4 PM AST THIS AFTERNOON
FOR PRZ001-003-005-007-008-010-011.
VI...NONE.
AM...NONE.
SHORT TERM...LIS
LONG TERM....ERG
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