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 190955 RRA
AFDSJU

AREA FORECAST DISCUSSION...DELAYED
NATIONAL WEATHER SERVICE SAN JUAN PR
555 AM AST FRI SEP 19 2014

.SYNOPSIS...A TROPICAL WAVE CROSSING THE EASTERN CARIBBEAN WITH AXIS
NOW ACROSS PUERTO RICO AND THE U.S.VIRGIN ISLANDS WILL CONTINUE WESTWARDS
AROUND 15 MPH. IN THE UPPER LEVELS AN ELONGATED TUTT LOW JUST NORTH
OF PUERTO RICO EXTENDS SOUTHWARDS ACROSS THE NORTHEASTERN CARIBBEAN.
THIS IS ALLOWING FOR GOOD VENTILATION AND DIVERGENCE ALOFT. ABUNDANT
AMOUNTS OF MOISTURE ACCOMPANYING THIS WAVE IS BEING ENHANCED BY THE
UPPER LOW AND PRODUCING MODERATE TO STRONG CONVECTION ACROSS THE
NORTHEASTERN CARIBBEAN...THE SURROUNDING COASTAL WATERS AS WELL AS
PARTS OF THE LOCAL ISLANDS.

&&

.DISCUSSION...HIGH PRESSURE RIDGE JUST NORTH OF THE AREA AND THE TROPICAL
WAVE MOVING ACROSS THE REGION WILL HELP TO MAINTAIN FAIRLY LOOSE PRESSURE
GRADIENT ACROSS THE REGION. THIS WILL RESULT IN LIGHT TO MODERATE EASTERLY
TRADE WINDS TODAY AND INTO THE WEEKEND. SIGNIFICANT AMOUNTS OF TROPICAL
MOISTURE CONVERGENCE IS ACCOMPANYING THE WAVE...WITH THE LATEST SATELLITE
DERIVED PRECIPITABLE WATER PRODUCT SUGGESTING A TONGUE OF HIGH PWAT
VALUES NEAR 2.5 INCHES NOW CROSSING THE REGION. THE PROXIMITY OF THE
UPPER LOW AND ASSOCIATED TROUGH ALONG WITH LOCAL AND DIURNAL EFFECTS...
WILL CONTINUE TO ENHANCE CONVECTION ACROSS THE REGION TODAY AND
POSSIBLE INTO EARLY SATURDAY. AS A RESULT EXPECTED ACTIVE AND VERY
UNSTABLE WEATHER CONDITIONS TO CONTINUE WITH PERIODS OF LOCALLY
HEAVY RAINFALL... AND HIGH POTENTIAL FOR THE DEVELOPMENT OF STRONG
THUNDERSTORMS...DANGEROUS CLOUD TO GROUND LIGHTNING...AND GUSTY
WINDS ACROSS PARTS OF THE ISLANDS DURING THE AFTERNOON HOURS. BY
LATE SATURDAY AND THROUGH MOST OF SUNDAY...EXPECT AN IMPROVEMENT
IN THE WEATHER CONDITIONS AS DRIER AIR MASS IS FORECAST TO QUICKLY
MOVE ACROSS THE REGION.

HOWEVER...BASED ON THE LATEST GFS MODEL GUIDANCE...ANOTHER TROPICAL
WAVE AND ASSOCIATED AREA OF LOW PRESSURE NOW NEAR 46 WEST WILL CONTINUE
WESTWARD...AND APPROACH THE LESSER ANTILLES LATE SATURDAY. IT IS TO
THEN FORECAST TO ENTER AND MOVE ACROSS THE EASTERN CARIBBEAN LATE SUNDAY
OR MONDAY AND BRING ANOTHER ROUND OF GOOD TROPICAL MOISTURE TO THE REGION.

&&

.AVIATION...SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE LOCAL
FLYING AREA TODAY AS A TROPICAL WAVE MOVES OVER THE REGION. SHRA/ISOLD
TSRA ASSOCIATED WITH THE WAVE WILL MOVE IN AND AROUND TJSJ AND TIST
AND TISX THIS MORNING. NEW SHWR/TSRA ACTIVITY IS EXPECTED FRIDAY AFT
OVER WESTERN SECTIONS OF PUERTO RICO. THEREFORE...MVFR/IFR CONDS AND
MOUNTAIN OBSCURATIONS CAN BE EXPECTED IN SHRA/TSRA IN MOST OF PR TERMINALS.
E TO SE WINDS OF 10-15 KT WILL PREVAIL BELOW FL150...WITH HIGHER GUSTS
AROUND 30 KT NEAR TSRA.

&&

.MARINE...OVERALL MARINE CONDITIONS WILL CONTINUE MAINLY 5 FEET
OR LESS WITH WINDS GENERALLY BELOW 18 KNOTS FOR THE NEXT FEW DAYS.
HOWEVER A TROPICAL WAVE MOVING ACROSS THE REGION TODAY WILL BRING
PERIODS OF ISOLATED TO SCATTERED THUNDERSTORM WITH AREAS OF LOCALLY
HEAVY RAINFALL AND STRONG GUSTY ACROSS PORTIONS OF THE COASTAL
WATERS. PLEASE REFER TO THE LATEST COASTAL WATERS FORECAST AND
MARINE WEATHER STATEMENTS ISSUED BY WFO SAN JUAN PUERTO RICO.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  88  78  88  79 /  70  10  20  20
STT  88  79  89  80 /  70  10  20  20

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...NONE.
&&

$$

72/09





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