072
FXCA62 TJSJ 020911
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
511 AM AST TUE DEC 2 2008
SYNOPSIS...AT UPPER LEVELS
HIGH PRESSURE JUST SOUTH OF THE
DOMINICAN REPUBLIC WILL SHIFT SOUTHEAST ON FRIDAY AND REMAIN OVER
THE SOUTHERN WINDWARD ISLANDS UNTIL A WEAK TROUGH PASSAGE TUESDAY
NIGHT OF NEXT WEEK.
AT MID LEVELS...HIGH PRESSURE NORTH OF PUERTO RICO WILL GRADUALLY
WEAKEN AND SHIFT INTO THE CARIBBEAN SEA BY FRIDAY WHERE IT WILL
REMAIN FOR MOST OF THE UPCOMING WEEK. CUT-OFF LOWS OF VARYING
STRENGTH WILL BE FOUND IN THE VICINITY OF 30 NORTH 40 WEST FOR
MOST OF THE SAME PERIOD. THE HIGH PRESSURE WILL KEEP THE MID
LEVELS DRY THROUGHOUT THE PERIOD.
AT LOWER LEVELS...A WEAK TROPICAL WAVE WILL BRUSH BY THE LOCAL
AREA TODAY TO THE SOUTH. AFTER WHICH...GENERALLY EAST NORTHEAST FLOW
WILL CAUSE PATCHES OF MOISTURE TO FORM IN THE VICINITY AND MOVE
WEST JUST SOUTH OF A SAGGING COLD FRONT THAT GETS ONLY AS FAR
SOUTH AS 23 NORTH BY FRIDAY. A SECOND FRONT WILL MOVE OUT OF THE
EASTERN UNITED STATES AND REACH 25 NORTH BY TUESDAY BEFORE
RETREATING AGAIN.
DISCUSSION
THE TOP OF THE MOIST LAYER REMAINS AT ABOUT 8
THOUSAND FEET. GOOD MOISTURE REMAINS BELOW THIS LEVEL AND VERY DRY
CONDITIONS ABOVE. THIS HAS LED TO SCATTERED SHOWERS NORTH OF
PUERTO RICO AND ALONG THE EAST COAST AND OVER THE CARIBBEAN. CELLS WERE
MOVING AT ABOUT 14 KNOTS. MIGRATORY HIGH PRESSURES CONTINUE MOVING
FROM WEST TO EAST ACROSS THE WESTERN ATLANTIC KEEPING FLOW HERE
GENERALLY EAST NORTHEAST. A WEAK TROPICAL WAVE IS PUSHING WEST TO
THE SOUTH OF THE AREA AND THE EARLY EVENING QUIKSCAT REVEALED
SOME HIGHER VELOCITY WINDS SOUTH OF PUERTO RICO AND STILL OVER THE
LESSER ANTILLES. THIS WILL SERVE TO KEEP WINDS A LITTLE STRONGER
TODAY OVER THE LOCAL AREA.
ANOTHER AREA OF GOOD MOISTURE MOVES IN ON WEDNESDAY AT LOWER LEVELS...AND
THIS MAY BE THE BEST MOISTURE TO BE SEEN UNTIL LATE AFTERNOON ON SUNDAY.
NEVERTHELESS CONDITIONS REMAIN UNFAVORABLE FOR DEEP CONVECTION AND
FRONTAL BOUNDARIES APPROACH FROM THE NORTH BUT DO NOT PASS THE
LOCAL AREA. A SLIGHT COOLING TREND OVER THE NEXT 10 DAYS MAY BE
OBSERVED...BUT THE OVERALL PATTERN CHANGES VERY LITTLE LOCALLY DURING
THIS PERIOD.
AVIATION
PREVAILING VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL
ISLANDS AND AT ALL LOCAL TAF SITES TODAY. HOWEVER...BRIEF MVFR
CONDITIONS ARE POSSIBLE ACROSS TISX...TIST...TNCM...AND TKPK EARLY
THIS MORNING IN PASSING SHRA. WINDS WILL BE MAINLY FROM THE EAST AT
10 TO 15 KNOTS EXCEPT FOR SEA BREEZE VARIATIONS AT COASTAL LOCATIONS.
MARINE
SEAS WILL INCREASE DUE TO INCREASING WINDS THROUGH THIS
MORNING...BUT THEN BEGIN TO TAPER OFF AS WINDS ALSO DECREASE. SEAS
ARE NOT EXPECTED TO BE GREATER THAN 8 FEET TODAY IN THE FORECAST
AREA. LONG PERIOD SWELL ARE NOT IN THE MODEL FORECAST FOR THE NEXT
8 DAYS AFTER A VERY WEAK EPISODE DECEMBER 4-6.
PRELIMINARY POINT TEMPS/POPS
SJU 84 72 84 73 / 20 30 30 20
STT 84 74 83 74 / 20 10 30 20
SJU WATCHES/WARNINGS/ADVISORIES
PR...SCA...AMZ710-712-715-722-725-732-741.
VI...SCA...AMZ710-715-722-725-732.
71/12/
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