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 061422
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1022 AM AST WED MAY 6 2015

.UPDATE...DOPPLER WEATHER RADAR DETECTED ONLY A COUPLE OF VERY LIGHT
SHOWERS ACROSS THE CARIBBEAN WATERS THIS MORNING. NOT PRECIPITATION
WAS DETECTED OVER LAND AREAS AND ELSEWHERE ACROSS THE FORECAST AREA
SO FAR THIS MORNING. A GENERALLY FAIR...MAINLY STABLE AND HAZY
WEATHER PATTERN WILL CONTINUE TO PREVAIL ACROSS THE REGION FOR THE
NEXT SEVERAL DAYS. HOWEVER...THE LIMITED AVAILABLE LOW LEVEL
MOISTURE ACROSS THE REGION WILL COMBINE WITH DAYTIME HEATING AND
LOCAL EFFECT TO PRODUCE SOME AFTERNOON CONVECTION ACROSS PORTIONS
OF WESTERN PUERTO RICO. THIS ACTIVITY IS EXPECTED TO LINGER INTO
THE EARLY EVENING HOURS WITH SOME SHOWERS EXPECTED TO BECOME MODERATE
TO LOCALLY HEAVY AT TIMES. BY THE EARLY EVENING...MOST OF THE
SHOWERS ARE EXPECTED TO DISSIPATE. HAZY SKIES WILL CONTINUE
ACROSS THE LOCAL ISLANDS FOR THE NEXT SEVERAL DAYS AS AN AREA OF
SAHARAN DUST CONTINUES OVER THE REGION. LOOKING AHEAD...COMPUTER
MODELS INDICATED THAT AN UPPER LEVEL TROUGH IS EXPECTED TO
APPROACH TO THE REGION BY THE END OF THE WEEK... INCREASING THE
MOISTURE TRANSPORT ACROSS THE REGION LATE IN THE UPCOMING WEEKEND
AND EARLY NEXT WEEK.

&&

.AVIATION...MOSTLY VFR CONDITIONS EXPECTED AT ALL TAF SITES THE
NEXT 24 HOURS WITH ONLY ISOLATED TO SCATTERED SHOWERS POSSIBLE
AFTER 06/18Z IN THE VICINITY OF TJBQ AND TJMZ. A SAHARAN AIR MASS
WILL REMAIN ACROSS THE LOCAL FLYING AREA...PRODUCING HAZY SKIES
FOR THE NEXT 24 HOURS. EAST SOUTHEAST WINDS OF 15 TO 20 KT ARE
EXPECTED THIS AFTERNOON WITH GUSTS UP TO 25 KT.

&&

.MARINE...WINDS UP TO 20 KNOTS AND SEAS UP TO 6 FEET ARE EXPECTED
ACROSS THE LOCAL COASTAL WATERS FOR THE NEXT FEW DAYS. SMALL CRAFT
ARE URGED TO EXERCISE CAUTION ACROSS MOST OF THE LOCAL WATERS.

&&

.FIRE WEATHER...HIGH FIRE WEATHER POTENTIAL IS EXPECTED TODAY
FOR SOUTHERN PR...VIEQUES AND ST CROIX. A RED FLAG WARNING IS
IN EFFECT FOR THOSE AREAS UNTIL 5 PM. FOR THE NEXT FEW DAYS WE
NEED TO MONITOR TRENDS AND DECIDE WHETHER A RED FLAG WARNING IS
WARRANTED.

&&

.PREV DISCUSSION... /ISSUED 419 AM AST WED MAY 6 2015/

SYNOPSIS...UPPER LEVEL RIDGE WILL WEAKEN RAPIDLY AFTER TODAY AS
CUTOFF LOW DEVELOPS OVER THE SOUTHEAST US. SAL WILL DOMINATE
THROUGH THE WEEKEND.

DISCUSSION...SAHARAN AIR LAYER WILL DOMINATE THROUGH THE WEEKEND
AND MAINTAIN MUCH DRYER THAN NORMAL CONDITIONS. AS UPPER LEVEL
CUTOFF LOW DEVELOPS OVER THE SOUTHEAST US...THE UPPER LEVEL RIDGE
WILL WEAKEN RAPIDLY AFTER TODAY THROUGH MID NEXT WEEK. HOWEVER...THE
MID LEVEL RIDGE WILL BE MUCH SLOWER TO WEAKEN BUT EVENTUALLY COLLAPSE
BY THE MIDDLE OF NEXT WEEK AS MID-UPPER LEVEL TROUGH OVER THE
BAHAMAS MOVES EWD. THE END RESULT IS A TREND TOWARD COOLER TEMPERATURES
AND BETTER MOISTURE FOR EARLY TO MID NEXT WEEK AS SUBSIDENCE INVERSION
WEAKENS AND ALLOWS FOR BETTER MOISTURE AND INSTABILITY. WHILE
CONDITIONS WILL BECOME MORE FVRBL FOR DEEP CONVECTION EARLY TO MID
WEEK...THE MODELS HOLD ON TO SOME MID-LEVEL DRY AIR AND FOCUS MUCH
OF THE ASSOCIATED RAINFALL NORTH OF 20N. EXPECT MAINLY SCT
AFTERNOON DEEP CONVECTION TO DEVELOP OVR NCNTRL/NW PR AS STEERING
WINDS REMAIN FROM THE SOUTHEAST. SO NO DROUGHT BUSTING RAINS ARE
EXPECTED BUT SOME RAIN IS BETTER THAN NO RAIN.

AVIATION...MAINLY VFR CONDITIONS EXPECTED ACROSS THE LOCAL FLYING
AREA FOR THE NEXT 24 HOURS. HZ DUE SAHARAN DUST BUT VSBY WILL REMAIN
P6SM. EASTERLY WINDS EXPECTED AT 15 TO 20 KT WITH GUSTS UP TO 25
KT.

MARINE...WINDS 20KT AND SEAS 4-6 FT INTO EARLY NEXT WEEK.

FIRE WEATHER...VERY NEAR RED FLAG YESTERDAY AT CAMP SANTIAGO AND
RED FLAG AT VIEQUES. CONDITIONS WILL BE SIMILAR TODAY WITH
PROBABLY LOWER RH`S BUT UNCERTAINTY LINGERS WITH RESPECT TO
WINDS. 06/00Z JSJ RAOB SHOWED A DIMINISHING TREND IN 925 MB WINDS
FROM 12Z AND WEAKER THAN FCST BY GFS. WILL CONTINUE TO MONITOR
TRENDS AND DECIDE WHETHER A RED FLAG WARNING IS WARRANTED. SIMILAR
AGAIN ON THU WITH INCREASING HIGH CLOUDS FRI AND THROUGH THE
WEEKEND MITIGATING THE FIRE DANGER SOMEWHAT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  90  79  91  79 /   0   0  10  10
STT  88  79  87  79 /   0   0   0  10

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...RED FLAG WARNING UNTIL 5 PM AST THIS AFTERNOON FOR CULEBRA-SOUTH
     COASTAL PLAINS AND MONA ISLAND.

VI...RED FLAG WARNING UNTIL 5 PM AST THIS AFTERNOON FOR ST CROIX.

AM...     SMALL CRAFT ADVISORY UNTIL 8 PM AST THIS EVENING FOR MONA
     PASSAGE SOUTHWARD TO 17N.

&&

$$

72/54


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