Puerto Rico Weather

Good morning. Scattered showers will dominate the weather today in PR as a wave moves thru.

AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
506 AM AST WED JUN 19 2013

.SYNOPSIS...MID TO UPPER LEVEL TROUGH OVER PUERTO RICO THIS MORNING
WILL RELOCATE WEST OF THE FORECAST AREA TONIGHT. SHOWERS AND
THUNDERSTORMS ASSOCIATED WITH A FAST MOVING TROPICAL WAVE WILL
CONTINUE TO SPREAD ACROSS THE LOCAL ISLANDS TODAY. THE TROUGH
ALOFT WILL ENHANCE THE CONVECTIVE INSTABILITY ACROSS THE REGION...
RESULTING IN MORE INTENSE SHOWERS AND THUNDERSTORMS. CONDITIONS
WILL IMPROVE ON THURSDAY AS A DRIER AIR MASS WITH SAHARAN DUST
MOVES OVER THE ISLANDS.

&&

.DISCUSSION...DOPPLER RADAR SHOWED NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS BETWEEN THE ANEGADA PASSAGE...U.S. VIRGIN ISLANDS
AND EASTERN PUERTO RICO THIS MORNING. MOST OF THE SHOWERS AND
THUNDERSTORMS ARE MOVING QUICKLY WESTWARD AT 20 KT. GUSTY WINDS
NEAR 37 KT WERE OBSERVED WITH THIS ACTIVITY...SPECIFICALLY AT BUOY
41052 JUST SOUTH OF ST JOHN. MOISTURE ASSOCIATED WITH THE WAVE
WILL QUICKLY SURGE ACROSS THE LOCAL AREA TODAY...REACHING A
MAXIMUM OF AROUND 2.25 INCHES BY 19/18Z. THIS TROPICAL WAVE WILL
BRING AN ACTIVE WEATHER PATTERN AS WELL AS SQUALLY WEATHER ACROSS
THE ISLANDS AND SURROUNDING WATERS THROUGH AT LEAST TONIGHT. THE
TROUGH ALOFT WILL COMBINE WITH THE DEEP MOISTURE AND INSTABILITY
OF THE WAVE TO ENHANCE THE CONVECTIVE DEVELOPMENT ACROSS THE FORECAST
AREA...INCREASING THE POTENTIAL FOR HEAVY RAINFALL...STRONG GUSTY
WINDS AND LOCALIZED FLOODING. OVERALL...EXPECT AN ACTIVE WEATHER
DAY WITH SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS AFFECTING THE
LOCAL ISLANDS THROUGH TONIGHT. WEATHER CONDITIONS WILL IMPROVE ON
THURSDAY AS DRIER AIR WITH A DECENT AMOUNT OF SAHARAN DUST WILL
MOVE OVER THE FORECAST AREA.

&&

.AVIATION...PERIODS OF MVFR CONDITIONS PSBL ACROSS TNCM...TKPK...
TIST AND TISX IN SHRA/TSRA ASSOCIATED WITH THE TROPICAL WAVE.
SHRA/TSRA WILL INCREASE ACROSS THE LOCAL TAF SITES BY 19/12Z AS
THE TROPICAL WAVE MOISTURE MOVES OVER THE REGION. TJSJ 19/00Z
SOUNDING INDICATED AN EASTERLY WIND FLOW OF 10-25 KNOTS ALL THE
WAY FROM THE SURFACE TO 15K FEET...BECOMING WESTERLY ALOFT.

&&

.MARINE...A SMALL CRAFT ADVISORY...SCA...IS IN EFFECT THROUGH
THURSDAY EVENING FOR FRESH TRADE WINDS AND ROUGH SEAS ASSOCIATED
WITH THE PASSAGE OF THE TROPICAL WAVE. WINDS WILL SUBSIDE THURSDAY
NIGHT...PROBABLY ENOUGH TO ALLOW US TO DROP THE SCA.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 88 78 / 50 50 40 0
STT 87 78 88 80 / 60 40 20 10

Things will improve starting on Thursday as dry air comes into the area.




AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
309 PM AST WED JUN 19 2013

.DISCUSSION...UPPER TROPOSPHERIC TROUGH IS RAPIDLY DRAWING
MOISTURE NORTHWARD AND...SO FAR...MOST OF THE THUNDERSTORMS ARE
GOING TOO. A LARGE BAND OF THUNDERSTORMS REMAINS IN THE CARIBBEAN
SOUTH OF USVI AT 15N TO 17N AND IT IS WRAPPING INTO ST. CROIX AND
TO CULEBRA. BUT NONE OF THESE ARE LIKELY TO MOVE TOWARDS PR SOON
SO AM NOT SURE ABOUT CARRYING VERY MANY SHOWERS INTO EVE. ONSHORE
FLOW MAY REGENERATE SOME SHOWERS ESPECIALLY ON THE SOUTHEAST PR
SLOPES IN NEXT FEW HOURS...AND IT CURRENTLY SHOWS A LITTLE
POTENTIAL FOR THAT.

THE SOUTHERN END OF THE THUNDERSTORMS NEAR 15N/65.5W IS HANDLED BY
THE GFS AS A WEAK REMNANT OF THE TROPICAL WAVE WHICH MOVES
NORTHWEST. GFS GOES A LITTLE NUTS OVER IT AS IT ENCOUNTERS GOOD
250 MB DIVERGENCE TONIGHT. THE RESULTING COVERGENCE AT 700 MB AND
DIVERGENCE AT 250 MB...ESPECIALLY AT THU/12Z SOUTH OF PR AT 16.6N
LOOKS LIKE CONVECTIVE FEEDBACK AND WILL NOT BITE. SO AM DISMISSING
THIS AS GFS SHOWS IT MOVING OVER THE ISLAND ON THU. CONVECTIVE
POTENTIAL ESPECIALLY DOES NOT LOOK SIGNIFICANT SINCE STRONG DRY
ADVECTION WILL OCCUR AS THE MOIST PLUME CONTINUES MOVING WEST AT
25 KNOTS...HAVING REACHED ANTILLES ATTM.

&&

.AVIATION...SHRA/TSRA GRDLLY DECR BUT THREAT OF MVFR/IFR STILL
POSBL. MOISTURE TO DROP OFF DURING THU DAYTIME. WIND BLO FL100
MAINLY SOUTHEAST 15-25 KT.

&&

.MARINE...SMALL CRAFT ADVISORY CONDITIONS TO CONTINUE INTO THU BUT
GRADUALLY DIMINISH.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 86 77 88 / 70 20 0 10
STT 77 86 78 88 / 90 20 10 10

Almost an inch before 5 PM but after that time more rain has fallen so more will be added.


WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST
VALUE (LST) VALUE VALUE FROM YEAR
NORMAL
..................................................................
TEMPERATURE (F)
TODAY
MAXIMUM 87 1139 AM 94 1981 89 -2 93
MINIMUM 74 459 PM 66 1909 78 -4 78
AVERAGE 81 83 -2 86

PRECIPITATION (IN)
TODAY 0.98 1.79 2010 0.14 0.84 0.01
MONTH TO DATE 6.55 2.92 3.63 0.03
SINCE JUN 1 6.55 2.92 3.63 0.03
SINCE JAN 1 31.08 21.60 9.48 25.58


Good morning. Moisture left behind by the Tropical Wave will combine with the Upper Trough to bring scattered showers today for PR and adjacent islands but better weather is expected starting on Friday and lasting thru the weekend.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
530 AM AST THU JUN 20 2013

.SYNOPSIS...TROPICAL UPPER TROPOSPHERIC TROUGH...TUTT...EXTENDS
FROM HISPANOLA INTO THE SW NORTH ATLANTIC THIS MORNING. THIS
TROUGH ALOFT WILL REMAIN WEST OF THE FORECAST AREA THROUGH AT
LEAST SATURDAY WHILE SLOWLY WEAKENS. LARGE AMOUNT OF MOISTURE LEFT
BEHIND BY THE TROPICAL WAVE WILL CONTINUE TO INTERACT WITH THE
TUTT TODAY. THEREFORE...AN UNSTABLE ATMOSPHERE COMBINED WITH HIGH
MOISTURE CONTENT WILL RESULT IN SCATTERED SHOWERS ACROSS PORTIONS
OF THE ISLANDS TODAY. MOISTURE WILL DECREASE ON FRIDAY...RESULTING
IN LESS CLOUD AND SHOWER COVERAGE ACROSS THE LOCAL AREA.

&&

.DISCUSSION...WATER VAPOR LOOP SHOWS A CYCLONIC CIRCULATION ASSOCIATED
WITH AFOREMENTIONED TUTT OVER HISPANOLA/SW NORTH ATLANTIC THIS MORNING.
IN ADDITION...IR SATELLITE IMAGERY SHOWED A LARGE AREA OF CLOUDS
AND SHOWERS THAT LIES ALONG AND BENEATH THE EASTERN FLANK OF TUTT.
DOPPLER WEATHER RADAR DETECTED SCATTERED TO NUMEROUS SHOWERS ACROSS
THE LOCAL WATERS AND THE U.S. VIRGIN ISLANDS DURING OVERNIGHT HOURS.
THIS PERSISTENT LIGHT TO MODERATE RAINFALL LEFT LESS THAN A QUARTER
OF AN INCH SINCE MIDNIGHT OVER THE U.S. VIRGIN ISLANDS. HOWEVER...
LITTLE RAINFALL WAS OBSERVED ACROSS PUERTO RICO OVERNIGHT.

SATELLITE DERIVED PWAT ANALYSIS SHOWS DEEP MOISTURE ACROSS THE
EASTERN CARIBBEAN THIS MORNING. THIS HIGH MOISTURE CONTENT
COMBINED WITH FAVORABLE UPPER DYNAMICS WILL BE ENOUGH TO FUEL
SCATTERED CONVECTION ACROSS PUERTO RICO AND THE USVI DURING THE
NEXT 12-18 HRS. UNDER A LLVL SOUTHERLY FLOW...SHOWERS WILL BE MORE
LIKELY ACROSS THE USVI..CULEBRA...VIEQUES AND EAST AND SOUTH
PORTIONS OF PUERTO RICO THE REST OF THE MORNING...FOLLOWED BY
SHOWERS AND A FEW THUNDERSTORMS DEVELOPING ACROSS THE INTERIOR...
WEST AND NORTHWEST SECTIONS OF PUERTO RICO IN THE AFTERNOON.

LATEST FORECAST CHARTS INDICATE SOME UPPER LEVEL RIDGING AND DRIER
AIR MASS OVER THE EASTERN CARIBBEAN ISLANDS FRIDAY THROUGH THE
UPCOMING WEEKEND. THIS WILL RESULT IN A GENERALLY STABLE AIR MASS
RETURNING TO THE FORECAST AREA.

&&

.AVIATION...PERIODS OF MVFR CONDITIONS WILL REMAIN POSSIBLE ACROSS
LOCAL TAF SITES AS LINGERING MOISTURE ASSOCIATED TO THE TROPICAL
WAVE CONTINUES TO INTERACT WITH UPPER LEVEL TROUGH TO THE NORTH OF
LOCAL ISLANDS. WIND BLO FL100 MAINLY SOUTHEAST 15-25 KT.

&&

.MARINE...WINDS AND SEAS SUBSIDED BELOW THE ADVISORY CRITERIA
ACROSS THE COASTAL WATERS OF PUERTO RICO AND THE USVI. AS A
RESULT...SCA FOR THESE MARINE ZONES WERE CANCELLED. IN CONTRAST...
CHOPPY CONDITIONS REMAIN ACROSS THE OFFSHORE WATERS...THEREFORE
SCA CONTINUE IN EFFECT FOR AMZ710-732-741 THROUGH LATE TONIGHT.
WINDS AND SEAS WILL SLOWLY SUBSIDED AFTER MIDNIGHT TONIGHT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 88 77 / 50 20 20 20
STT 88 78 88 78 / 40 20 20 20

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1014 PM AST THU JUN 20 2013

.UPDATE...THE DOPPLER WEATHER RADAR DETECTED ONLY FEW ISOLATED
SHOWERS ACROSS THE SURROUNDING WATERS...BUT NOT PRECIPITATION WAS
DETECTED OVER LAND AREAS SO FAR THIS EVENING. A GENERALLY
DRY...STABLE AND HAZY AIR MASS ENCOMPASSED RAPIDLY THE LOCAL ISLANDS
TODAY BEHIND THE TROPICAL WAVE...JUST ACROSS HISPANIOLA THIS
EVENING. HOWEVER...LATEST SATELLITE IMAGES THIS EVENING DEPICTED
ABUNDANT RAIN FREE MID TO HIGH LEVEL CLOUDINESS STREAMING ACROSS THE
REGION FROM THE SOUTH SOUTHEAST IN ASSOCIATION WITH THE BROAD
CIRCULATION OF A TUTT LOW JUST NORTH OF HISPANIOLA TONIGHT. AS THE
TROPICAL WAVE MOVES WESTWARD WELL AWAY FROM THE FORECAST AREA...A
GENERALLY DRY...STABLE AND HAZY AIR MASS IS EXPECTED TO REMAIN OVER
THE REGION FOR THE UPCOMING WEEKEND. HOWEVER...THE LIMITED AVAILABLE
MOISTURE WILL COMBINE EACH DAY WITH DAYTIME HEATING AND LOCAL
OROGRAPHIC EFFECTS TO INDUCE THE DEVELOPMENT OF SHOWERS AND A FEW
THUNDERSTORMS ACROSS WESTERN AND INTERIOR PUERTO RICO EACH
AFTERNOON. A TROPICAL WAVE EMERGING FROM THE AFRICAN COAST TODAY
WILL CONTINUE TO MOVE WESTWARD DURING THE NEXT SEVERAL DAYS...AND
ACCORDINGLY TO THE GFS MODEL GUIDANCE...IS EXPECTED TO REACH THE
LOCAL REGION BY NEXT WEDNESDAY.

Good afternoon. Wave will move thru on Monday bringing some scattered showers but the stronger wave on Wednesday promises a little more rainfall.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
304 PM AST FRI JUN 21 2013

.SYNOPSIS...AT UPPER LEVELS...A WEAK CUT OFF LOW JUST NORTHWEST OF
THE LOCAL AREA WILL RETREAT TO THE NORTH VERY SLOWLY WHILE HIGH
PRESSURE FROM THE TROPICAL ATLANTIC BUILDS OVER THE EASTERN AND
CENTRAL CARIBBEAN THROUGH THE WEEKEND. THE TROUGH WILL STRENGTHEN
SLIGHTLY AND MOVE INTO THE AREA AGAIN BEGINNING ON WEDNESDAY.
WINDS BECOME NORTHWESTERLY THURSDAY THROUGH SUNDAY.

AT MID LEVELS...RIDGING CONTINUES OVER THE EASTERN CARIBBEAN FOR
MUCH OF THE UPCOMING WEEK. PATCHES OF MOISTURE ARE FORECAST FOR
SATURDAY NIGHT AND THE TWO TROPICAL WAVES MONDAY AND LATE
WEDNESDAY INTO THURSDAY.

AT LOWER LEVELS...HIGH PRESSURE CONTINUES ACROSS THE ATLANTIC FROM
NORTH OF 30 DEGREES NORTH...BUT MAINTAINS LOCAL TRADE WINDS AT
MODERATE TO FRESH FORCE THROUGH THE NEXT 10 DAYS. SOME SAHARAN
DUST IS ALSO BEING CARRIED. MOISTURE IS GENERALLY LIMITED ABOVE 7
KFT EXCEPT SATURDAY NIGHT AND EARLY SUNDAY MORNING AND AGAIN LATE
WEDNESDAY. THE WAVE PASSAGE ON MONDAY APPEARS WEAK IN THE MOST
RECENT MODELS.

&&

.DISCUSSION...ONLY A FEW SMALL SHOWERS HAVE APPEARED SO FAR THIS
AFTERNOON. SOME AS A STREAMER OFF OF VIEQUES AND ONE OR TWO OVER
WESTERN PUERTO RICO. ACCUMULATIONS HAVE BEEN INSIGNIFICANT. HIGH
PRESSURE AT MID LEVELS AND DRIER SAHARAN AIR ABOVE 7 KFT HAVE
CAPPED MOST ACTIVITY. THIS SITUATION WILL CONTINUE THROUGH
TONIGHT. MOISTURE INCREASES SHARPLY SATURDAY NIGHT...DROPS ON
SUNDAY NIGHT AND RISES AGAIN ON MONDAY. THEN ANOTHER TROPICAL WAVE
MOVES INTO THE AREA LATE ON WEDNESDAY WITH PRECIPITABLE WATER
RISING TO ABOVE 2 INCHES. THE GFS SHOWS MOISTURE DIMINISHING AGAIN
ON THURSDAY AND REMAINING MODEST THROUGH THE FOLLOWING SUNDAY
NIGHT. WITH LITTLE CHANGE IN THE SURFACE FLOW AND WITH MID LEVELS
DOMINATED WITH HIGH PRESSURE. ONLY THE UPPER LEVEL TROUGHS AND THE
LOWER LEVEL MOISTURE FLUCTUATIONS WILL BE SIGNIFICANT IN
VARIATIONS OF SHOWER ACTIVITY. AT PRESENT THE BEST MOISTURE
APPEARS TO ARRIVE WITH THE SECOND TROPICAL WAVE ON WEDNESDAY...BUT
WIDESPREAD FLOODING IS STILL NOT EXPECTED IN PART DUE TO THE GOOD
TRADE WINDS AND THE PRESENCE OF SAHARAN AIR ABOVE THE MARINE
LAYER.

&&

.AVIATION...
VFR CONDITIONS EXPECTED TO PREVAIL AT ALL SITES FOR THE NEXT 24
HOURS. VCSH ARE POSSIBLE FOR TJPS AND TJMZ THIS AFTERNOON AND OVR
INTERIOR/SW PR WITH MTN OBSC. WINDS FROM SFC TO 2K FT WILL REMAIN
FROM ENE AT 5 TO 15 KTS AT LEAST UNTIL TONIGHT. LAND BREEZES ARE
EXPECTED AFT 21/22Z.

&&

.MARINE...MODERATE TO FRESH TRADE WINDS ARE MAINTAINING SEAS OF 4
TO 6 FEET ACROSS MOST EXPOSED WATERS. THIS SITUATION IS EXPECTED
TO CONTINUE THROUGH THE NEXT 7 DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 88 77 88 / 30 20 40 40
STT 78 88 78 89 / 30 30 40 40