842
FXCA62 TJSJ 180826
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
426 AM AST MON NOV 18 2024
SYNOPSIS
MARINE AND COASTAL CONDITIONS WILL REMAIN DETERIORATED TODAY AS A
NORTHERLY SWELL CONTINUES TO INVADE THE ATLANTIC WATERS. THIS
CONDITIONS SHOULD IMPROVE BY THIS EVENING OR TOMORROW. DRIER AND
COOLER AIR MOVED IN, BRINGING FAIR WEATHER THROUGH THE FIRST HALF
OF THE WORKWEEK. SHOWERS WILL INCREASE ONCE AGAIN AFTER THURSDAY.
SHORT TERM...TODAY THROUGH WEDNESDAY
CURRENT SATELLITE DERIVED PRECIPITABLE WATER (PWAT) VALUES CONFIRMS
NOTABLY DRIER AIR APPROACHING THE ISLANDS FROM THE NORTH, BEHIND THE
COLD FRONT THAT MOVED OVER THE REGION YESTERDAY. BY 400 AM, PWAT
VALUES OVER PUERTO RICO WERE AROUND 1.2 TO 1.45 IN. AT THE SAME
TIME, PWAT OVER VIEQUES, CULEBRA AND THE NORTHERN USVI WERE SOMEWHAT
HIGHER (1.6 TO 1.7 IN) WHILE OVER ST. CROIX IT WAS AROUND 1.85 IN.
SINCE MIDNIGHT, LINGERING LIGHT SHOWERS CONTINUED TO AFFECT THE
EASTERN THIRD OF PUERTO RICO, AND SECTORS OF THE LOCAL ISLANDS. THIS
ACTIVITY HAS BEEN GRADUALLY DECREASING IN COVERAGE THROUGHOUT THE
OVERNIGHT HOURS. THE FRONTAL BOUNDARY AND ASSOCIATED SHOWERS AND
THUNDERSTORMS ARE ALREADY SOUTH OF ST. CROIX. REPORTED OVERNIGHT
LOWS WERE IN THE LOW TO UPPER 60S OVER HIGHER ELEVATIONS OF PUERTO
RICO AND IN THE MID 70S TO AROUND 80 ACROSS LOWER ELEVATIONS OF THE
ISLANDS.
COOLER AND DRIER AIR WILL CONTINUE TO FILTER INTO THE ISLANDS UNDER
NORTHERLY FLOW THROUGH WEDNESDAY. CURRENT MODEL GUIDANCE HAS PWAT
VALUES OF 0.9 TO 1.3 INCHES, WELL BELOW TO BELOW NORMAL VALUES FOR
THIS TIME OF THE YEAR. MID TO UPPER LEVEL RIDGING WILL MOVE IN FROM
THE SOUTHEASTERN U.S. INTO THE WESTERN CARIBBEAN, MAINTAINING A
TRADE WIND CAP INVERSION AROUND 850 MB, WITH ALL THE LOW LEVEL
MOISTURE TRAPPED BELOW THIS LEVEL. LOW LEVEL MOISTURE AS WELL AS
925MB TEMPERATURES ARE FORECAST TO BE BELOW NORMAL DURING THE
PERIOD. GENERALLY LOW PROBABILITY OF PRECIPITATION (POP) WILL
REMAIN, EXCEPT DURING POSIBLE AFTERNOON CONVECTION AND ALSO JUST
SOUTHEAST OF SAINT CROIX, WHERE REMNANT MOISTURE FROM THE FRONT WILL
LINGER. 500 MB TEMPERATURES WILL ALSO WARM UP, FURTHER DIMINISHING
DEEP CONVECTION ACTIVITY POSSIBILITIES. SURFACE WINDS WILL BE
GENERALLY NORTHEASTERLY, WITH AN EASTERLY COMPONENT STARTING TO
FURTHER DOMINATE BY LATE WEDNESDAY, AS A SURFACE HIGH GRADUALLY
MOVES IN FROM OUR NORTHWEST. GENERALLY STABLE CONDITIONS WILL
PREVAIL DURING MOST OF THE PERIOD WITH TEMPERATURES COOLING DOWN TO
BELOW CLIMATOLOGICAL VALUES.
LONG TERM...THURSDAY THROUGH MONDAY
THE WEATHER PATTERN WILL SHIFT TO A WETTER ONE ONCE AGAIN. AS A
SURFACE TO MID-LEVEL HIGH BUILDS WEST OVER THE EASTERN ATLANTIC,
THE WIND FLOW WILL SHIFT WILL GAIN A MORE SOUTHERLY COMPONENT,
PULLING MOISTURE FROM THE CARIBBEAN INTO THE REGION. SO FAR, THE
GLOBAL GUIDANCE INDICATE THAT THE BULK OF THE MOISTURE WILL MOVE
CLOSER TO THE DOMINICAN REPUBLIC, BUT PRECIPITABLE WATER SHOULD
STILL GO ABOVE NORMAL FROM THURSDAY THROUGH SATURDAY. THIS WILL
BRING AN INCREASE IN SHOWERS AND THUNDERSTORMS FOR THE ISLANDS,
INCREASING THE RISK FOR FLOODING. ALSO, UNDER A DEEP-LAYERED
SOUTHERLY FLOW, TEMPERATURES WILL SOAR ONCE AGAIN, AND THE WARMER
THAN NORMAL HEAT WILL RETURN, EXCEPT ON AREAS WHERE THE CLOUD DECK
REMAINS THICK ENOUGH. FOR SUNDAY, A POCKET OF DRIER AIR WILL MOVE
IN, GIVING THE ISLANDS A BREAK FROM THE WET PATTERN, BUT IT LOOKS
LIKE ANOTHER SURGE OF MOISTURE WILL APPROACH FROM THE EAST EARLY
NEXT WEEK, WITH ANOTHER ROUND OF RAIN FOR THE EASTERN CARIBBEAN.
AVIATION
(06Z TAFS)
MAINLY VFR CONDITIONS ARE FORECAST TO PREVAIL ACROSS THE TERMINALS.
VCSH WILL LINGER DURING THE EARLY MORNING HOURS AND AT TIMES WILL BE
BROUGHT IN BY NORTHEASTERLY FLOW. AFTER 18Z, CONVECTIVE VCSH
POSSIBLY AFFECTING TJPS. LOW LEVEL NE WINDS WILL BE UP TO 12 KTS
WITH HIGHER GUSTS AND SEA BREEZE VARIATIONS.
MARINE
GENTLE TO MODERATE NORTHERLY WINDS WILL PREVAIL THROUGH LATE WEDNESDAY
WHEN EASTERLY WINDS RETURN. MARINE CONDITIONS WILL BE UNFAVORABLE FOR
SMALL CRAFT THROUGH TODAY DUE TO ADDITIONAL PULSES OF NORTHERLY
SWELLS. THE REMNANTS OF A COLD FRONT JUST SOUTH OF THE REGION WILL
BRING ADDITIONAL SHOWERS AND ISOLATED THUNDERSTORMS TO THE CARIBBEAN
WATERS.
BEACH FORECAST
THE LOCAL BUOYS STILL SHOW SEAS 6 TO 8 FEET ACROSS NORTHERN PUERTO
RICO, WITH A PERIOD OF 12 TO 13 SECONDS. THIS WILL RESULT IN
DANGEROUS HIGH SURF DUE TO BREAKING WAVES ABOVE 10 FEET. FOR
VIEQUES, CULEBRA, SAINT THOMAS AND SAINT JOHN, THE RIP CURRENT
RISK IS HIGH, AND MODERATE IS SAINT THOMAS.
MINOR COASTAL FLOODING AND BEACH EROSION IS ALSO POSSIBLE IN THE
MOST VULNERABLE BEACHES OF NORTHERN PUERTO RICO. THE HIGH TIDE
IN SAN JUAN WILL BE AT 11:13 AM AST, AT 2.06 FT.
CONDITIONS SHOULD IMPROVE BY THE EVENING OR TOMORROW, BUT STILL
WITH A MODERATE RIP CURRENT RISK IN EFFECT.
SJU WATCHES/WARNINGS/ADVISORIES
PR...COASTAL FLOOD ADVISORY UNTIL NOON AST TODAY FOR PRZ001-002-005-
008.
HIGH RIP CURRENT RISK THROUGH THIS AFTERNOON FOR PRZ001-002-005-
008-010-012-013.
HIGH SURF ADVISORY UNTIL 6 PM AST THIS EVENING FOR PRZ001-002-
005-008-012.
VI...HIGH RIP CURRENT RISK THROUGH THIS AFTERNOON FOR VIZ001.
HIGH SURF ADVISORY UNTIL 6 PM AST THIS EVENING FOR VIZ001.
AM...SMALL CRAFT ADVISORY UNTIL 6 PM AST THIS EVENING FOR AMZ711-712-
716-741-742.
SHORT TERM...MRR
LONG TERM....ERG
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