Area Forecast Discussion
Issued by NWS San Juan, PR

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000
FXCA62 TJSJ 280747
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
347 AM AST FRI NOV 28 2014

.SYNOPSIS...UPPER LEVEL RIDGE WILL BUILD OVR THE LOCAL AREA TODAY
THEN FLATTEN DURING THE WEEKEND. A SRN STREAM TROUGH WILL MOVE
ACROSS THE AREA SUN THEN SHORTWAVE RIDGE BUILDS MON AND TUE.

&&

.DISCUSSION...STRONG SUBSIDENCE INVERSION AND SPARSE LOW LEVEL
MOISTURE WILL INHIBIT CONVECTIVE DEVELOPMENT TODAY. INVERSION BEGINS TO
WEAKEN SAT AS UPPER RIDGE FLATTENS/WEAKENS STEEPENING LAPSE RATES
AND PROMOTING MOISTURE TRANSPORT WITH SCT RW/TSRA EXPECTED TO
DEVELOP OVR NCNTRL PR SAT AFTERNOON. AN UPPER LEVEL TROUGH MOVES
THROUGH THE AREA SUN BUT IT APPEARS AREA WILL REMAIN UNDER
UNFAVORABLE RIGHT EXIT REGION OF JET STREAK. STRENGTHENING TRADE
WINDS MAY ALSO LIMIT SEA BREEZE DEVELOPMENT. MODELS OVERALL LOOK
LESS ENTHUSIASTIC WITH PRECIP POTENTIAL SUN THAN ON SAT. SHORTWAVE
RIDGE BUILDS MON AND TUE AND TRADE WINDS STRENGTHEN TO 20 KT
INHIBITING SEA BREEZE DEVELOPMENT. DURING DECEMBER...DIURNAL
CONVECTION TAKES A SIG DOWNWARD TURN AND SHIFTS MORE TO EASTERN
PR. OVERALL...NOT EXPECTING MUCH WX MON AND TUE.

DURING THE REST OF NEXT WEEK...MODELS MAINTAIN AN ACTIVE SUBTROPICAL
JET STREAM NORTH OF THE AREA WITH WEAK HEIGHT FALLS AT 500 MB AND
PULSES OF SHORTWAVE ENERGY GRAZING THE FCST AREA. FLOW ALOFT
REMAINS TOO ZONAL WITH NOT MUCH AMPLIFICATION. DETERMINISTIC 00Z GFS
APPEARS WAY OVERDONE WITH SIG MOISTURE TRANSPORT INTO THE NE
CARIBBEAN AND WITH A LOW PRES FCST TO LIFT NORTH FROM THE SCNTRL
CARIBBEAN. GIVEN THE LACK OF AMPLIFICATION SEEN ON GEFS ENSEMBLE
MEMBERS WITH MID-UPPER LEVEL TROUGH OVR THE BAHAMAS AND WRN
CARIBBEAN...PREFER THE MORE SUPPRESSED AND DRYER SOLUTIONS OF THE
00Z GEFS AND 00Z ECMWF KEEPING LOW PRES SUPPRESSED AND DEEP
MOISTURE WELL SOUTH OF THE LOCAL AREA BUT DO EXPECT TO SEE
SIGNIFICANT AMOUNTS OF HIGH CLOUDS DUE TO PRESENCE OF ACTIVE
SUBTROPICAL JET.


&&

.AVIATION...VFR CONDS WILL PREVAIL FOR THE NEXT 24 HOURS AT ALL TAF
SITES. FEW PASSING -SHRA W/SCT CLD LYRS PSBL BTW FL020-FL050 OVR
THE ATL WATERS N OF PR AND BTW ERN PR AND NRN LEEWARDS TIL 28/12Z.
DURG REST OF THE DAY FM 28/12Z-28/22Z...MOSTLY FAIR WX SKIES/VFR
WITH SLIGHT CHC OF ISOLD -SHRA/SHRA MAINLY OVR WEST/CTRL INT SECTION
OF PR. NO SIG OPERATIONAL WX IMPACT ATTM. L/LVL WND MAINLY LGT FM
ENE LESS THAN 10 KNOTS BLO FL200. SFC WND MOSTLY TO CALM TIL 28/14Z
BCMG LGT/VRB DURG DAY WITH LCL SEA BREEZE VARIATIONS ALONG COASTAL
AND AT TAF SITES TIL 28/22Z.


&&

.MARINE...LIGHT TRADE WINDS TODAY THEN STRENGTHEN SAT THROUGH
MON WITH SPEEDS UP TO 20 KT. SEAS HAVE COME DOWN TO 2-4 FT BUT ARE
EXPECTED TO BUILD TO 5-7 FT BY MON IN MIXED NNW SWELLS AND NE WIND WAVES.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  85  76  85  79 /   0   0  20  20
STT  86  78  86  79 /  10  20  20  20

&&

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

$$

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