Area Forecast Discussion
Issued by NWS San Juan, PR

Home | 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 181938
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
338 PM AST SAT APR 18 2015

.DISCUSSION...UPPER LEVEL (250 MB SHORTWAVE WITH UPPER DIVERGENCE
OVER SAN JUAN (PERCEIVED BY GFS) IS APPARENTLY HAVING LITTLE
IMPACT IN ENHANCING CONVECTION OVER NORTHERN PR SO FAR. WATER
VAPOR LOOP IMPLIES THE WAVE IS MOVING AT A SLOWER PACE WITH THE
400 MB AXIS STILL OVER HISPANIOLA. SOMEWHAT LIMITED MOISTURE (1.45
INCHES PRECIPITABLE WATER) MAY BE A LIMITING FACTOR TOO.

GFS SOUNDINGS LOOK FAIRLY UNSTABLE ON SUNDAY AS PRECIPITABLE WATER
INCREASES TO 1.71 AT TJSJ WHILE CAPE AND LIFTED INDEX CLIMB TO
RESPECTABLE LEVELS. GFS SHOWS ANOTHER 250 MB SHORTWAVE LOOMING IN
VICINITY OF PR AGAIN WITH DIVERGENCE THAT LEVEL. INCREASED THE
PROBABILITY OF PRECIPITATION AND COVERAGE OF THUNDER FOR NORTHWEST
PR. BUT MOS GUIDANCE CONTINUES RATHER LOW FOR SURFACE DEW POINTS
AND REMAINED A LITTLE CONSERVATIVE.

&&

.AVIATION...VFR THRU SUNDAY XCP IN SCT SHRA/TSRA BOTH AFT WEST AND
NORTHWEST PR ALG WI SOME OBSCD MTNS. SCT SHRA TONITE FM SOUTH PR
TO USVI. WIND THRU SUNDAY BLO FL100 SE TO S 5-15 KT BCMG W AND
INCR ABV.

&&

.MARINE...BUOY 41043 CURRENTLY ALMOST 7 FT AND A LITTLE HIGHER
THAN MODELS INDICATE...WHICH DO HAVE HEIGHTS ALMOST THAT HIGH BUT
DECREASE THEM AS THEY PASS SOUTHEAST. WILL HAVE TO MONITOR THIS
AND SEE IF RAISING THEM IN FORECAST IS WARRANTED. OTHERWISE 3-5 FT
STILL LOOKS OK AS TRADES TO REMAIN WEAK TO MODERATE. HIGH PRESSURE
IN CENTRAL ATLANTIC TO CONTINUE MOVING AWAY WHILE RIDGE DIRECTLY
NORTH WILL STAY WEAK AT LEAST UNTIL MID-WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  89  76  89 /  30  20  30  30
STT  76  85  77  85 /  40  40  50  50

&&

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

$$

10/54



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