Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 061804
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
204 PM AST FRI MAY 6 2016

.SYNOPSIS...AT UPPER LEVELS...HIGH PRESSURE RIDGING BETWEEN
PUERTO RICO AND THE U.S. VIRGIN ISLANDS WILL BE SQUEEZED OVER TO
THE LEEWARD ISLANDS BY MONDAY...BUT AN APPROACHING TROUGH WILL
STALL OVER HISPANIOLA KEEPING SOUTHWEST WINDS AND LINES OF STRONG
DIVERGENCE OVER THE AREA THROUGH FRIDAY. HIGH PRESSURE RETURNS
OVER THE NEXT WEEKEND BUT AREAS OF DIVERGENCE WILL CONTINUE TO
MIGRATE THROUGH.

AT MID LEVELS...HIGH PRESSURE CONTINUES OVER THE CENTRAL ATLANTIC
NORTHEAST OF PUERTO RICO WHILE A PINCHED OFF LOW FROM A STRONG
LONG WAVE TROUGH ROTATES TO THE NORTHEAST AND DISSIPATES. WEAK
GRADIENTS OVER THE LOCAL AREA IN GENERALLY HIGH PRESSURE REMAIN
BEYOND THE FOLLOWING WEEK. MID LEVELS WILL BE CHARACTERIZED BY
MORE MOISTURE NEXT WEEK.

AT LOWER LEVELS...STRONG HIGH PRESSURE OVER THE CENTRAL ATLANTIC
WEAKENS CONSIDERABLY THROUGH THURSDAY AND THEN RECEDES TO THE
NORTHEAST TO RECHARGE. NEARLY SOUTHERLY WINDS BECOME MORE EAST
SOUTHEAST OR EAST EARLY IN THE WEEK ALLOWING SOME NORTH COAST
COOLING. MOISTURE INCREASES SLOWLY THROUGH TUESDAY AND THEN
BREATHES A LITTLE BEFORE INCREASING AGAIN THURSDAY AND FRIDAY OF
NEXT WEEK. A COLD FRONT WILL APPROACH THE AREA FROM THE
NORTHWEST...BUT IT APPEARS THAT ONLY THE PRE-FRONTAL BOUNDARY WILL
ACTUALLY AFFECT PUERTO RICO AND THE U.S. VIRGIN ISLANDS WITH
INCREASED SHOWERS AND THUNDERSTORMS.

&&

.DISCUSSION...15 TO 25 KNOT WINDS FROM THE SOUTH SOUTHEAST ONLY
MADE THEIR PRESENCE FELT MORE AS WARMING AND MIXING BROUGHT DOWN
GUSTY WINDS THAT FOUGHT OFF THE SEA BREEZE THE ENTIRE DAY. A CAP
BETWEEN 5 AND 6 KFT ALSO SLOWED ANY CONVECTION THAT WAS NOT
SHEARED OFF AS WINDS TURNED WESTERLY AT 18 KFT. ALTHOUGH TOMORROW
WILL HAVE A LITTLE MORE MOISTURE AND SHOWERS...THE CAP WILL
INCREASE SOMEWHAT AND LIMIT THE SHOWER ACTIVITY. ON SUNDAY WE SEE
EVEN BETTER MOISTURE AND INSTABILITY AS THE BOUNDARY APPROACHES.
FINALLY ON MONDAY A BIT OF A CRESCENDO AS THE BOUNDARY REACHES
ITS CLOSEST APPROACH. MOISTURE IMPROVES AGAIN ON
WEDNESDAY...HOWEVER...AND SHOWERS WILL ALSO INCREASE. HENCE WE
MAY RESUME A WET WEEK AND SEE MORE POTENTIAL FOR URBAN AND SMALL
STREAM FLOODING. PART OF THIS INCREASE WILL BE OWED TO THE
MULTIPLE AREAS OF DIVERGENCE THAT WILL TRANSIT THE AREA FROM THE
SOUTHWEST BEGINNING MONDAY. HIGH CLOUDS AND WEAKER STABILITY
SHOULD PRECLUDE ANY EPISODE OF SEVERE WEATHER HOWEVER.

&&

.AVIATION...VFR COND AT ALL TAF SITES THROUGH FCST PRD. ISOLD SHRA
EN ROUTE BTW ISLANDS BUT MOSTLY CLR OVR LAND AREAS FM 07/00Z-07/09Z.
L/LVL WNDS FM SE-S BLO FL150...BCM SW-W ABV AND INCR W/HT. SFC WND
LGT AND VRB OVR LAND. NO SIG OPS WX HAZARDS ATTM.


&&

.MARINE...SEAS PEAK ON THE 8TH AND THE 10TH OF MAY AT THE OUTER
BUOY...REACHING ALMOST 7 FEET...HOWEVER SEAS SHOULD REMAIN BELOW 7
FEET THE ENTIRE PERIOD IN THE LOCAL OUTER ATLANTIC WATERS. THE
CARIBBEAN WILL GENERALLY BE A FOOT OR SO MORE TRANQUIL THAN THE
ATLANTIC.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  79  91  78  89 /   0  50  40  50
STT  82  86  80  86 /  30  40  40  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
AM...NONE.
&&

$$

09/12


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