Area Forecast Discussion
Issued by NWS San Juan, PR

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 210333
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1133 PM AST WED AUG 20 2014

.UPDATE...SHOWERS AND THUNDERSTORM ACTIVITY ACROSS THE LOCAL
ISLANDS AND COASTAL WATERS MOVED OFFSHORE AND DIMINISHED DURING
THE EARLY EVENING...LEAVING PARTLY CLOUDY SKIES WITH ONLY A FEW
LIGHT SHOWERS BRUSHING PARTS OF THE NORTH AND EAST COASTAL SECTIONS
OF SOME OF THE ISLANDS. ISOLATED THUNDERSTORMS ENHANCED BY THE TUTT
LOW NOW ACROSS HISPANIOLA...CONTINUED OVER PARTS OF THE MONA PASSAGE
WHILE MOVING WESTWARD. DURING THE REST OF THE OVERNIGHT HOURS...
EXPECT PASSING EARLY MORNING SHOWERS TO AFFECT MAINLY PARTS OF
THE NORTH AND EAST COASTAL SECTIONS OF PUERTO RICO AND THE ADJACENT
ISLANDS. ON THURSDAY...EXPECT INCREASING TROPICAL MOISTURE ACROSS
THE REGION WITH RAPIDLY DETERIORATING WEATHER CONDITIONS BY
THURSDAY EVENING AND CONTINUING THROUGH FRIDAY...AS THE AREA OF
LOW PRESSURE AND ASSOCIATED TROPICAL WAVE ENTERS AND MOVES WEST
NORTHWEST ACROSS THE EASTERN CARIBBEAN. NO MAJOR CHANGES MADE TO
THE INHERITED LONG TERM FORECAST PACKAGE AT THIS TIME... HOWEVER
DID MODIFY AND ADJUST THE SHORT TERM BASED ON THE LATEST MODEL
GUIDANCE AND PRESENT WEATHER CONDITIONS.

AS FAR AS THE ELONGATED AREA OF LOW PRESSURE AND ASSOCIATED
TROPICAL WAVE EAST OF THE WINDWARD ISLANDS...RECENT SATELLITE
IMAGERY SHOWED INCREASED CONVECTIVE CLUSTERS FORMING JUST NORTH
AND EAST OF THIS FEATURE. BASED ON LATEST INFORMATION FROM THE
NATIONAL HURRICANE CENTER ADDITIONAL DEVELOPMENT REMAINS POSSIBLE
DURING THE NEXT DAY OR TWO. REGARDLESS OF WEATHER THIS FEATURE
BECOMES A TROPICAL CYCLONE OR NOT...ALL INDICATIONS AT THIS TIME
SUGGEST MEDIUM TO HIGH POTENTIAL FOR GUSTY WINDS...DANGEROUS SQUALLS
AS WELL AS HEAVY RAINFALL ACROSS THE LOCAL ISLANDS AND COASTAL WATERS
BEGINNING AS SOON AS THURSDAY NIGHT AND CONTINUING THROUGH FRIDAY.
ALL LOCAL INTEREST SHOULD CONTINUE TO CLOSELY MONITOR THE PROGRESS
OF THIS SYSTEM.

&&

.AVIATION...MOSTLY VFR CONDITIONS EXPECTED AT ALL TERMINALS DURING
THE OVERNIGHT. HOWEVER...AFTER 21/12Z VCTS EXPECTED THROUGH THE FCST
PERIOD AROUND TKPK/TNCM. THEN...AFTER 21/16Z TSRA/SHRA DEVELOPMENT
OVER THE INTERIOR/WESTERN PR WILL RESULT IN BRIEF MVFR CONDS WITH
MTN TOP OBSCURATIONS AT TJMZ AND TJPS. THE 21/00Z TJSJ SOUNDING
INDICATED EAST WINDS FM SFC TO AROUND 5 KFT AT 5-19 KTS...BCMG E-NE
AT 10-20 KTS AFTER 21/12Z.

&&

.MARINE UPDATE...NO SIGNIFICANT CHANGES TO PREVIOUS MARINE DISCUSSION
AT THIS TIME. WINDS AND SEAS WILL AT 5 FEET OR LESS AND 17 KNOTS
OR LESS RESPECTIVELY DURING THE OVERNIGHT HOURS. HOWEVER AS PREVIOUSLY
MENTIONED...GRADUALLY INCREASING WINDS AND SEAS ON THURSDAY WITH
DETERIORATING MARINE CONDITIONS EXPECTED BY THURSDAY EVENING AS
THE PREVIOUSLY MENTIONED AREA OF LOW PRESSURE AND ASSOCIATED TROPICAL
WAVE IS FORECAST TO MOVE ACROSS THE REGIONAL WATERS. PLEASE REFER
TO THE LATEST COASTAL WATERS FORECAST AND OTHER MARINE WEATHER
MESSAGES ISSUED BY WFO SAN JUAN PR FOR ADDITIONAL UPDATES.

&&

.PREV DISCUSSION... /ISSUED 323 PM AST WED AUG 20 2014/

DISCUSSION...
TUTT LOW TO THE NORTHWEST OF THE AREA WILL CONTINUE RETROGRADING
ACROSS HISPANIOLA THROUGH TONIGHT. AN UPPER HIGH PRESSURE RIDGE
WILL MOVE IN AS A WELL ORGANIZED TROPICAL WAVE APPROACHES THE
LEEWARD ISLANDS ON THURSDAY...THEN REACHING THE CARIBBEAN WATERS
LATE ON THURSDAY INTO FRIDAY. THIS SURFACE LOW AND ASSOCIATED WAVE
IS EXPECTED TO BRING NUMEROUS SHOWERS TO THE LOCAL AREA.

THE LOW PRESSURE EAST OF THE WINDWARD ISLANDS IS EXPECTED TO
GRADUALLY CONTINUE DEVELOPING THROUGH THE NEXT FEW DAYS. THIS LOW
PRESSURE IS FORECAST TO REACH THE CARIBBEAN WATERS LATE THURSDAY
AND CONTINUE ON THROUGH FRIDAY. HOWEVER THE DEEP TROPICAL MOISTURE
THAT THIS FEATURE WILL BRING WILL PROBABLY LINGER THROUGH THE
WEEKEND AND INTO EARLY MONDAY. GFS MODEL HAS PRECIPITABLE WATER
VALUES CLOSE TO 2 INCHES STARTING LATE THURSDAY...BUT INCREASING
EVEN MORE TO OVER 2.5 INCHES BY LATE FRIDAY. SOME HEAVY RAINFALL
AND STRONG GUSTY WINDS ARE POSSIBLE WITH THIS LOW PRESSURE.

THE NATIONAL HURRICANE CENTER GIVES THE LOW PRESSURE EAST OF THE
WINDWARD ISLANDS A 50 PERCENT CHANCE OF DEVELOPMENT INTO A
TROPICAL CYCLONE WITHIN THE NEXT 48 HOURS. PLEASE REFER TO THE
TROPICAL WEATHER OUTLOOKS FROM NATIONAL HURRICANE CENTER FOR THE
LATEST INFORMATION ABOUT THIS LOW PRESSURE SYSTEM.

AVIATION...
IFR TSRAS VCNTY JBQ/JMZ THRU 21/00Z...OTHERWISE PREVAILING VFR
CONDITIONS ALL TERMINALS THROUGH THE FCST PERIOD. ERLY SFC/LOW
LEVEL WINDS 10-20 KTS THRU 21/00Z...BCMG 5-10KTS AFT 21/00Z.

MARINE...
MODERATE TO FRESH TRADE WIND BREEZE THROUGH THU MORNING. WINDS
FRESHENING THU AFTERNOON AS A WELL ORGANIZED TROPICAL WAVE PUSHES
ACROSS THE NORTHEAST CARIBBEAN. WINDS 20-25 KT POSSIBLE AND SEAS
6-8 FT DURING THIS PERIOD THU THRU SAT AS THE WAVE PUSHES ACROSS
THE AREAS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  79  89  77  86 /  40  60  60  90
STT  79  90  79  89 /  40  50  60  90

&&

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

$$

13/09





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