Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 290249
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1049 PM AST MON JUL 28 2014

.UPDATE...A TUTT LOW NORTH OF THE REGION WILL INDUCE A WEAK LOW LEVEL
TROUGH WHICH WILL MOVE ACROSS THE NORTHEASTERN CARIBBEAN OVERNIGHT
THROUGH TUESDAY. LATEST SATELLITE IMAGERY SHOWED ONLY PATCHES OF SHALLOW
LOW LEVEL MOISTURE WITH THIS FEATURE. THEREFORE...EXPECT ONLY OCCASIONAL
PASSING CLOUDS AND A FEW TUTT ENHANCED SHOWERS MAINLY ACROSS THE OFFSHORE
ATLANTIC COASTAL WATERS DURING THE OVERNIGHT AND EARLY MORNING HOURS.
SURFACE HIGH PRESSURE CENTERED ACROSS THE NORTH CENTRAL ATLANTIC WILL
CONTINUE TO SLOWLY RETREAT FURTHER NORTH OF THE REGION THROUGH MIDDLE
OF THE WEEK WHILE RELAXING THE LOCAL PRESSURE GRADIENT. THIS IN TURN
WILL LEAD TO FAIRLY LIGHT EAST SOUTH EAST TRADE WINDS THROUGH AT LEAST
MID WEEK. LATEST TJSJ 29/00Z UPPER AIR SOUNDING SHOWED PWAT VALUES STILL
AROUND 1.70 INCHES ACROSS THE REGION...WITH MODEL GUIDANCE SUGGESTING
EVEN DRIER CONDITIONS DURING THE LATTER PART OF THE WORK WEEK. NO MAJOR
CHANGES MADE TO THE INHERITED SHORT TERM FORECAST PACKAGE AT THIS TIME.

LATEST UPDATE ON THE TROPICAL WAVE PREVIOUSLY MENTIONED AS PER NATIONAL
HURRICANE CENTER TROPICAL WEATHER OUTLOOK...THE SHOWERS AND THUNDERSTORM
ACTIVITY ASSOCIATED WITH THIS WAVE HAS BECOME A LITTLE BETTER ORGANIZED
DURING THE PAST FEW HOURS. ENVIRONMENTAL CONDITIONS ARE STILL EXPECTED
TO BE CONDUCIVE FOR GRADUAL DEVELOPMENT AND A TROPICAL DEPRESSION COULD
FORM DURING THE NEXT SEVERAL DAYS...A THIS FEATURE MOVES GENERALLY WESTWARD
OR WEST NORTHWEST AT 10 TO 15 MPH. THE LATEST TROPICAL WEATHER UPDATE
AT 8 PM AST NOW SUGGEST A MEDIUM CHANCE...50 PERCENT FOR FORMATION
THROUGH 48 HOURS. STAY TUNED FOR ADDITIONS UPDATES.

&&

.AVIATION UPDATE...VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES
THROUGH THE FCST PERIOD. HOWEVER...BETWEEN 29/16-21Z BRIEF MTN TOP
OBSCR AND MVFR CIGS ARE EXPECTED DUE SHRA/TSRA DEVELOPING ACROSS
THE CENTRAL INTERIOR AND NORTHWESTERN SECTION OF PR AFFECTING
MAINLY TJBQ AND TJMZ. E-SE WINDS 5-15 KTS BELOW 5 KFT.

&&

.MARINE UPDATE...NO SIGNIFICANT CHANGES TO THE PREVIOUS MARINE DISCUSSION.
LATEST OBS FROM SURROUNDING BUOYS AS WELL AS MODEL GUIDANCE...SUGGEST
FAIRLY TRANQUIL SEAS OF 4 FEET OR LESS AND WINDS OF 16 KNOTS OR LESS
OVERNIGHT.

&&

.PREV DISCUSSION... /ISSUED 252 PM AST MON JUL 28 2014/

SYNOPSIS...SURFACE HIGH PRESSURE ACROSS THE CENTRAL ATLANTIC WILL
REMAIN DOMINATING THE GENERAL WEATHER PATTERN FOR THE NEXT FEW
DAYS WITH EASTERLY WINDS AND LOWER THAN NORMAL PRECIPITABLE WATER
VALUES AS IT SLOWLY MOVES NORTH. TUTT TO THE NORTH OF THE LOCAL
ISLANDS WILL REMAIN IN PLACE TO THE NORTH OF THE ISLANDS FOR THE
NEXT FEW DAYS. STRONG TROPICAL WAVE LOCATED ACROSS THE TROPICAL
CENTRAL ATLANTIC WILL CONTINUE TO MOVE WEST AND WILL APPROACH THE
NORTHEAST CARIBBEAN BY THE WEEKEND.

DISCUSSION...SHOWERS WITH THUNDERSTORMS DEVELOPED THIS AFTERNOON
OVER SOUTH CENTRAL AND SOUTHWEST SECTION OF PUERTO RICO. THIS
ACTIVITY WAS ASSOCIATED DUE TO THE COMBINATION OF AVAILABLE
MOISTURE WITH LOCAL EFFECTS AND A UPPER LEVEL LOW NORTH OF THE
AREA. THIS TROUGH OF LOW PRESSURE WILL CONTINUE TO MEANDER ACROSS
THE REGION NEXT SEVERAL DAYS. THIS SAME TROUGH WILL PLAY AN
IMPORTANT ROLE ON THE FUTURE TRACK OF THE TROPICAL WAVE LOCATED
THIS AFTERNOON NEAR 10 NORTH LATITUDE AND 33 WEST LONGITUDE. PER
LATEST NATIONAL HURRICANE CENTER TROPICAL WEATHER OUTLOOK...
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR GRADUAL
DEVELOPMENT OF THIS DISTURBANCE OVER THE NEXT SEVERAL DAYS WHILE
IT MOVES GENERALLY WESTWARD AT 10 TO 15 MPH.

IT IS TOO EARLY TO PRECISE JUST HOW MUCH OR EVEN IF THIS WAVE WILL
AFFECT THE LOCAL AREA AS A WAVE OR TROPICAL CYCLONE...IF AT ALL.
THERE IS JUST TOO MUCH UNCERTAINTY AT THIS TIME AND THERE IS GREAT
DIFFERENCES BETWEEN GLOBAL MODELS. WE ARE OBSERVING THE TROPICAL
WAVE CLOSELY AND ITS EVOLUTION...BUT IT IS JUST TOO EARLY YET TO
PRECISE HOW OR EVEN IF THIS WILL AFFECT THE LOCAL AREA. STAY TUNED
FOR FURTHER INFORMATION.

AVIATION...VCTS NEAR TJPS AND TJMZ THROUGH AT LEAST 28/22Z.
ELSEWHERE...VFR CONDITIONS WILL CONTINUE TO PREVAIL THROUGH
TOMORROW MORNING.

MARINE...SURFACE PRESSURE GRADIENT ACROSS THE NORTHEAST CARIBBEAN
WILL CONTINUE TO RELAX AS THE SURFACE HIGH PRESSURE RIDGE...CENTERED
OVER THE NORTH-CENTRAL ATLANTIC...CONTINUES TO SLOWLY RETREAT
NORTH. AS A RESULT RESULT...SEAS WILL REMAIN BELOW 6 FEET THROUGH
AT LEAST FRIDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  76  88  77  89 /  20  30  20  20
STT  78  89  78  88 /  20  20  20  20

&&

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

$$

13/09




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