FXCA62 TJSJ 201433
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1033 AM AST TUE JAN 20 2009
.DISCUSSION...
MOSTLY CLOUDY SKIES ALONG WITH WIDELY SCT SHRA COVER THE ERN HALF
OF PR AND THE USVI LATE THIS MORNING AS SEEN ON LATEST VISIBLE
AND RADAR IMAGERY. ALSO...PWAT ESTIMATES FROM POES INDICATE VALUES
NEAR 2.0 INCHES OVR THE USVI AND JUST WEST OF THE LEEWARD ISLANDS.
THIS WILL CONTINUE TO BE ADVECTED WWD TOWARD PR LATER TODAY UNDER
EASTERLY FLOW. SO IN GENERAL A BIT MORE SHOWER ACTIVITY EXPECTED
THIS AFTERNOON WHEN COMPARED TO THE LAST COUPLE OF DAYS BUT
NOTHING SIGNIFICANT.
&&
.AVIATION...VFR CONDITIONS NEXT 24 HRS. BRIEF MVFR CONDITIONS
POSSIBLE WRN PR TAF SITES WITH ANY SHOWER. 
&&
.PREV DISCUSSION... /ISSUED 529 AM AST TUE JAN 20 2009/ 
SYNOPSIS...AT UPPER LEVELS...HIGH PRESSURE WILL SHIFT FROM THE
EASTERN CARIBBEAN INTO THE CENTRAL CARIBBEAN LATE IN THE WEEK AS A
MID LATITUDE TROUGH PUSHES EAST OUT OF THE EASTERN UNITED STATES.
AT MID LEVELS...WEAK MOISTURE PUSHES OUT OF THE SOUTHEAST OVER THE
LOCAL AREA TONIGHT AND EARLY WEDNESDAY. THIS MOISTURE GIVES WAY TO
VERY DRY AIR THROUGH FRIDAY. DURING THIS TIME HIGH PRESSURE
MAINTAINS CONTROL OF THE CENTRAL ATLANTIC JUST NORTH OF THE
TROPICS FROM WHICH RIDGING EXTENDS SOUTHWEST ACROSS THE CARIBBEAN.
WEAK GRADIENTS OVER THE LOCAL AREA PREVAIL AFTER THE WEEKEND.
AT LOWER LEVELS...HIGH PRESSURE IN THE EAST CENTRAL ATLANTIC IS
BRINGING A BAND OF MOISTURE IN FROM THE SOUTHEAST THIS MORNING
WHILE A FRONTAL BAND HOVERS OVER HISPANIOLA AND STRETCHES
NORTHEAST. THE FRONT DISSIPATES PRETTY MUCH IN PLACE FRIDAY AND
OVER THE WEEKEND WHILE WEAK BANDS OF MOISTURE AND PATCHES OF DRIER
AIR MOVE THROUGH THE TRADE WIND FLOW OVER THE LOCAL AREA.
DISCUSSION... A PLUME OF MOISTURE FROM THE SOUTHEAST HAS ENTERED
THE EASTERN CARIBBEAN AND IS WORKING ITS WAY OVER SAINT THOMAS AND
CULEBRA. SHOWERS OVER LAND HAVE BEEN MINOR...BUT HEAVY SHOWERS
FORMED NORTH OF SAINT THOMAS AND ARE MOVING OUT OF THE FORECAST
AREA. AFTER DAWN SOME OF THIS MOISTURE WILL REACH EASTERN PUERTO
RICO WHERE CLOUDS AND SHOWERS WILL INCREASE. BY AFTERNOON...THIS
PLUME WILL HAVE REACHED WESTERN PUERTO RICO AND WILL BRING
SCATTERED SHOWERS TO THE NORTHWEST PORTION OF THE ISLAND. SOME
MOISTURE LINGERS IN THE FLOW UNTIL LATE WEDNESDAY NIGHT IN BOTH
THE GFS AND NAM MODELS. THE PROGNOSIS IS FOR SOMEWHAT DRIER AIR ON
THURSDAY AWAITING ANOTHER BAND OF MOISTURE DUE ON FRIDAY NIGHT.
THEN...IF THE GFS IS TO BE BELIEVED MOISTURE DIMINISHES OVER THE
WEEKEND. THERE IS LITTLE SIGNIFICANT CHANGE TO THE ATMOSPHERIC
PATTERN DURING THE NEXT 10 DAYS.
AVIATION...MAINLY VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF
SITES THROUGH 20/16Z. A LINE OF SHOWERS WAS AFFECTING TISX...AND TIST
FROM 09-12Z...PRODUCING BRIEF PERIODS OF MVFR CONDITIONS. DURING
THE AFTERNOON...MVFR CONDITIONS AND SOME MOUNTAIN OBSCURATIONS ARE
POSSIBLE ACROSS TJMZ AND TJBQ AS SCATTERED SHOWERS DEVELOP ACROSS
THESE AIRPORTS. WINDS WILL BE MAINLY EAST SOUTHEAST TODAY...EXCEPT
FOR SEA BREEZE VARIATIONS IN THE COASTAL AREAS.
MARINE...MINOR CHANGES ONLY IN THE SEA HEIGHTS OF THE ATLANTIC
AND CARIBBEAN WATERS ARE EXPECTED IN THE NEXT SEVEN DAYS. CARIBBEAN
WATERS WILL PEAK FROM 4 TO 5 FEET ON WEDNESDAY AND MODEL SEES NO
HIGHER SEAS THEREAFTER. ATLANTIC WATERS WILL BE BORDERLINE SMALL
CRAFT ADVISORY CONDITIONS THURSDAY AND THURSDAY NIGHT.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU  82  74  86  74 /  40  10  20  20 
STT  79  75  82  75 /  40  30  30  10 
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
&&
$$
64/12/