Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 080239
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1039 PM AST SUN FEB 7 2016

.UPDATE...
FAIR WEATHER CONDITIONS PREVAILED AS A DRY AIR MASS MOVED ACROSS
THE REGION...DURING THE AFTERNOON AND INTO THE EVENING. TRANQUIL
WEATHER CONDITIONS ARE EXPECTED TO CONTINUE WITH MINIMUM
TEMPERATURES IN THE MID MID 70S ALONG THE COASTAL SECTION AND IN
THE MID 60S IN THE MOUNTAINOUS AREAS. NO CHANGES WERE MADE TO THE
PREVIOUS DISCUSSION.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL DURING THE NEXT
24 HOURS ACROSS ALL TERMINALS. LATEST TJSJ SOUNDING INDICATED A
VARIABLE WIND FLOW AT 5 TO 9 KT BELOW 2KFT. THEREFORE...EXPECT SFC
WNDS OVERNIGHT LIGHT AND VARIABLE DUE TO LAND BREEZE.

&&

.MARINE....SMALL CRAFT OPERATORS SHOULD EXERCISE CAUTION ACROSS
THE ATLANTIC OFFSHORE WATERS AND MONA PASSAGE DUE TO SEAS UP TO 6
FT AND WINDS AROUND 18 KT. ELSEWHERE...MARINERS CAN EXPECT SEAS
BELOW 5 FT AND WINDS AT 10 TO 15 KT.

&&

.PREV DISCUSSION... /ISSUED /

SYNOPSIS...AT UPPER LEVELS...A WEAK RIDGE EXTENDS OVER THE LOCAL
AREA FROM THE SOUTHWEST. THIS RIDGE WILL DRIFT OVER THE LEEWARD
ISLANDS BY WEDNESDAY AND THE WINDWARD ISLANDS BY SATURDAY. A LONG
WAVE TROUGH WILL MOVE OVER THE AREA BY THE FOLLOWING MONDAY.

AT MID LEVELS...HIGH PRESSURE CONTINUES OVER THE CARIBBEAN AND
INTO THE CENTRAL ATLANTIC UNTIL NEXT WEEKEND WHEN A LONG WAVE
TROUGH DIGS INTO THE WESTERN ATLANTIC NORTH OF THE LOCAL AREA. MID
LEVELS DRY OUT SLOWLY DURING THE WEEK...BUT MOISTURE RETURNS NEXT
WEEKEND AND PEAKS THE FOLLOWING MONDAY.

AT LOWER LEVELS...LOW PRESSURE GROWS QUICKLY OVERNIGHT JUST
OUTSIDE THE NORTH CAROLINA COASTAL WATERS. HIGH PRESSURE WILL
CONTINUE IN THE EAST CENTRAL ATLANTIC BEYOND VALENTINES DAY. A
RIDGE OF HIGH PRESSURE WILL CONTINUE ACROSS THE ATLANTIC NORTH OF
THE AREA AND LOW PRESSURE WILL CONTINUE AND DEEPEN SOMEWHAT OVER
THE COLOMBIAN COAST. THIS WILL ALLOW A SURFACE TROUGH TO APPROACH
THE AREA DURING THE UPCOMING WORK WEEK AND KEEP TRADE WINDS OVER
THE AREA EAST SOUTHEASTERLY.

DISCUSSION...A BAND OF SHOWERS MOVED WEST NORTHWEST ACROSS THE
EASTERN HALF OF PUERTO RICO AND LEFT ONE QUARTER TO ONE HALF INCH
OR MORE IN MANY PLACES. DURING THE MORNING IT BROKE IN HALF WITH
THE NORTHERN HALF MOVING BAYAMON AND OUT INTO THE ATLANTIC AND THE
SOUTHERN HALF MOVING THROUGH PONCE AND DISSIPATING IN UTUADO. FEW
SHOWER WERE SEEN NORTHWEST OF THIS. SOME SHOWERS LINGERED OVER THE
EASTERN TIP OF PUERTO RICO AS A STREAMER FROM SAINT CROIX CROSSED
VIEQUES AND MOVED THROUGH FAJARDO.

ALTHOUGH DRIER AIR CONTINUES OVER THE WESTERN TROPICAL ATLANTIC
AND THE WATERS NORTH OF THE LEEWARD ISLANDS. MODELS SUGGEST THAT
AREAS OF MOISTURE DEVELOP TO OUR EAST AND KEEP PRECIPITABLE WATER
VALUES AROUND 1.4 INCHES UNTIL THURSDAY. THEN MOISTURE LEVELS DROP
TO 0.85 INCHES ON FRIDAY MORNING BEFORE INCREASING ABOVE 1.5
INCHES SATURDAY AFTERNOON WHEN THE APPROACH OF A FRONTAL SYSTEM
WILL BEGIN THE CHANCES OF BETTER RAINFALL OVER THE AREA. THIS
MODERATE LEVEL OF MOISTURE DURING THE WEEK WILL BRING ISOLATED TO
SCATTERED SHOWERS IN THE TYPICAL DIURNAL PATTER EACH DAY....WITH
SHOWERS ON THE WINDWARD SLOPES IN THE LATE NIGHTS AND EARLY
MORNINGS AND TO A LESSER EXTENT SOME SHOWERS IN WESTERN PUERTO
RICO DURING THE AFTERNOONS. NEVERTHELESS THOSE SHOWERS IN WESTERN
PUERTO RICO...ALTHOUGH FORECAST BY THE MODELS...HAVE MADE A SCANT
SHOWING DURING THE LAST SEVERAL DAYS OWING THE THE SEVERITY OF THE
DRYNESS OF THE MID LAYERS. THIS SHOULD END ON SATURDAY.

AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL DURING THE NEXT
24 HOURS ACROSS ALL TERMINALS. SFC WNDS OVERNIGHT LIGHT AND VARIABLE
DUE TO LAND BREEZE. HOWEVER...WINDS BLO FL150 WILL CONTINUE FROM
THE SE AT 10-15 KTS.

MARINE...SEAS WILL REMAIN AGITATED BUT BELOW SMALL CRAFT ADVISORY
LEVELS UNTIL EARLY TUESDAY MORNING. AT THAT TIME SWELL OF 6 TO 8
FEET ARE EXPECTED TO ENTER THE LOCAL AREA TUESDAY MORNING FROM
THE NORTHWEST HAVING BEEN GENERATED BY THE STORM NOW RAPIDLY
DEVELOPING IN THE ATLANTIC OFF THE NORTH CAROLINA COAST. SOME
RELIEF FROM THIS SHOULD BE EXPECTED BY THURSDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  74  88  74  88 /  10  20  10  20
STT  75  85  75  87 /  20  20  30  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
AM...NONE.
&&

$$

11/27


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