Area Forecast Discussion
Issued by NWS San Juan, PR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXCA62 TJSJ 060024
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
824 PM AST THU MAY 5 2016

.UPDATE...THE AFTERNOON SHOWERS ACROSS NORTHWEST PUERTO RICO
DISSIPATED RAPIDLY AFTER SUNSET LEAVING PARTLY CLOUDY SKIES WITH
ONLY ISOLATED SHOWERS ACROSS EASTERN AND SOUTHERN SECTIONS OF
PUERTO RICO. THE UPPER LEVEL TROUGH THAT AFFECTED THE REGION
DURING THE PAST SEVERAL DAYS HAD FINALLY MOVED WELL TO THE EAST OF
THE REGION. AN UPPER LEVEL RIDGE WILL CONTINUE TO BUILD OVER THE
REGION UNTIL SATURDAY. THIS FEATURE WILL LIMIT THE SHOWERS AND
THUNDERSTORMS DEVELOPMENT ACROSS THE LOCAL ISLANDS AND SURROUNDING
WATERS FOR THE NEXT COUPLE OF DAYS. HOWEVER...THE LINGERING LOW
LEVEL MOISTURE WILL BE ENOUGH TO CREATE SOME SHOWERS ACROSS THE
U.S. VIRGIN ISLANDS...VIEQUES...CULEBRA...EASTERN AND SOUTH PUERTO
RICO DURING THE NIGHT AND SOME AFTERNOON CONVECTION ACROSS
INTERIOR AND NORTHWEST PUERTO RICO EACH AFTERNOON.

AN UPPER TROUGH AND A FRONTAL BOUNDARY ACROSS EASTERN CUBA...
HAITI AND LAS BAHAMAS IS EXPECTED TO INCREASE THE INSTABILITY
ACROSS THE REGION SUNDAY AND MONDAY. THESE FEATURES WILL INCREASE
AGAIN THE CHANCES OF SHOWERS AND THUNDERSTORMS ACROSS THE
NORTHEAST CARIBBEAN.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH
06/16Z. PERIODS OF MVFR CONDITIONS WITH MOUNTAIN OBSCURATIONS ARE
EXPECTED OVER TJMZ AND TJBQ BTW 06/16 AND 06/22Z. LOW LEVEL WINDS
WILL BE MAINLY SOUTHEAST AT AROUND 10 KNOTS OVERNIGHT...INCREASING
TO 10 TO 15 KTS AFTER 06/14Z.

&&

.MARINE...SEAS UP TO 5 FEET AND WINDS UP TO 20 KNOTS ARE EXPECTED
ACROSS THE REGION TONIGHT AND FOR THE UPCOMING WEEKEND.

&&

.PREV DISCUSSION... /ISSUED /

SYNOPSIS...BROAD UPPER TROUGH WILL AMPLIFY SLOWLY ACROSS THE
WESTERN ATLANTIC INTO THE CARIBBEAN DURING THE NEXT FEW DAYS. MID
TO UPPER RIDGE WILL BUILD QUICKLY OVER THE AREA THROUGH SATURDAY.
SURFACE HIGH PRESSURE WILL CONTINUE ACROSS THE CENTRAL ATLANTIC
WHILE SURFACE LOW AND ASSOCIATED FRONT OVER THE WESTERN ATLANTIC
CONTINUES TO MOVE FARTHER NORTH INDUCING A DEEP LAYER SOUTHERLY
WIND FLOW ACROSS THE FORECAST AREA.

DISCUSSION...LOCALLY INDUCED AFTERNOON SHOWERS FORMED OVER THE NW
QUADRANT OF THE ISLAND EARLY IN THE AFTERNOON. SO FAR...RAINFALL
ACCUMULATIONS ARE LESS THAN ONE INCH AS ESTIMATED BY THE DOPPLER
RADAR. A FEW SHOWERS WERE ALSO NOTED ACROSS EL YUNQUE AREA AND
SOME MOVING OVER THE CARIBBEAN WATERS THAT WILL EVENTUALLY REACH
THE SOUTHEASTERN SECTIONS OF PR DURING THE REST OF THE AFTERNOON
HOURS.

MID TO UPPER RIDGE OVER THE CARIBBEAN BASIN WILL PROMOTE SOMEWHAT
DRIER AIR AND UNFAVORABLE DYNAMICS ACROSS THE FORECAST AREA
THROUGH AT LEAST SATURDAY. HOWEVER...THE AVAILABLE LOW LEVEL MOISTURE
WILL BE ENOUGH TO CREATE TRADE WIND SHOWER ACTIVITY UNDER
SOUTHERLY WIND FLOW ACROSS THE USVI/SOUTHEASTERN SECTIONS OF PR
EACH NIGHT AND DURING THE EARLY MORNING HOURS...FOLLOWED BY
LOCALLY INDUCED AFTERNOON SHOWERS NORTH OF THE CORDILLERA.

FOR LATE SUNDAY INTO EARLY NEXT WEEK...THE DEEP LAYERED TROUGH AND
ASSOCIATED FRONTAL BOUNDARY WILL MOVE OVER FROM THE
WEST...INCREASING FAVORABLE UPPER LEVEL DYNAMICS AND LOW LEVEL
CONVERGENCE ACROSS THE MONA PASSAGE AND THE ATLANTIC WATERS. THIS
IN TURN WILL FAVOR ENHANCED AFTERNOON CONVECTION OVER THE MOUNTAIN
RANGED AND THE NORTHERN AREAS OF PR. AS WINDS CONTINUE FROM THE
SOUTH...SLIGHTLY ABOVE WARMER THAN NORMAL TEMPERATURES ARE
EXPECTED THROUGH AT LEAST SATURDAY AFTERNOON. AS UPPER TROUGH
APPROACHES ON SUNDAY...HIGH CIRRUS CLOUDS WILL MOVE OVER THE
ISLANDS AND THIS IN TURN CAN KEEP TEMPS AT NORMAL LEVELS...AND
ALSO OFFSET THE TIME OF THE DIURNALLY INDUCED AFTERNOON SHOWERS.

AVIATION...MOSTLY VFR CONDS WILL CONTINUE ACROSS THE TAF SITES
DURG PRD. SCT OCNL BKN CLD LYR FL025...050. AT LEAST UNTIL 05/23Z
VCSH/PSBL ISOLD MAY DEVELOP OVER THE INTERIOR SECTIONS OF PR AND
STEER NORTHWEST IN THE VCNTY OF/OR ACROSS TJBQ...TJSJ...TJMZ.  SHRA
VCTY OF TISX...TIST...TNCM TIL 05/23Z.  SFC WINDS WILL BE MAINLY SE
EXCEPT FOR SEA BREEZE VARIATIONS ALONG THE COASTAL AREAS...AROUND 5-
15 KTS TIL 05/23Z.

MARINE...SEAS SHOULD CONTINUE BELOW 5 FEET THROUGH THE WEEKEND.
WINDS WILL BE FROM THE SOUTHEAST GENERALLY BETWEEN 10-15
KNOTS...WITH OCCASIONAL HIGHER GUSTS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  91  78  91 /  20  40  10  50
STT  79  86  79  86 /  30  30  10  40

&&

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

$$

23/72


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.