Debris Flow in Puerto Rico, May 14, 2004

PUERTO RICO AND U.S. VIRGIN ISLANDS FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
923 PM AST THU MAY 13 2004

.UPDATE...THE 00Z SOUNDING REVEALED A WET AND UNSTABLE SOUNDING
THAT HAD 1.86 INCHES OF PRECIPITABLE WATER AND A LIFTED INDEX OF
-6.7. ALTHOUGH THERE WAS A 1 DECREE C INVERSION BETWEEN 6600 AND
8000 FEET...ONCE ON THEIR WAY...AIR PARCELS WOULD HAVE LITTLE
TROUBLE RISING THROUGH TO 200 MB...AND THIS IS HAPPENING WEST OF
CABO ROJO.

CONSIDERABLE SHOWER ACTIVITY WITH EMBEDDED THUNDERSTORMS CONTINUE TO
STREAM ACROSS THE CARIBBEAN SOUTH OF PUERTO RICO AND ALSO ALONG THE
EAST NORTHEAST FLOW FROM CABO ROJO. MODELS INDICATE THAT THE MOIST
AIRMASS THAT HAD BEEN PRODUCING THE HEAVY RAIN YESTERDAY DID NOT
STRAY FAR FROM THE AREA...AND WAS ONLY PUT OFF TODAY BY THE INVASION
OF A DRY PATCH OF AIR AT LOWER LEVELS. BETTER UPPER LEVEL DIVERGENCE
IN THE REGION OF THE RIGHT ENTRANCE OF THE JET SHOULD HELP
CONVECTION TOMORROW...AND SATURDAY...AND NEW MOISTURE WILL ARRIVE ON
THE SOUTHEAST COAST BEGINNING AT 18Z ON FRIDAY. DOES NOT LOOK LIKE
SURFACE FLOW WILL SHIFT SIGNIFICANTLY AWAY FROM EAST NORTHEAST
TOMORROW...ALTHOUGH THE 850 MB FLOW DOES TURN SLIGHTLY SOUTH OF
EAST. IT MAY BE DIFFICULT TO ARRIVE AT 86 DEGREES AT THE ASOS IN SAN
JUAN WITH A GOOD SEA BREEZE...BUT THERE SHOULD BE A LITTLE MORE SUN
SO WILL LEAVE THE TEMPERATURES ALONE TONIGHT. OTHER AREAS LOOK
REASONABLE AS WELL...AS WE ARE IN A PERIOD WITH VERY LITTLE
VARIATION IN MAXIMA AND NOT TOO MUCH DIURNAL DIFFERENCES EITHER.

THE WEEKEND CONTINUES TO LOOK WET...ESPECIALLY SATURDAY. WOULD
EXPECT THAT A NUMBER OF AREAS WILL SEE FLOODING THEN AS WINDS
CONTINUE TO FAVOR THE NORTHERN SIDE OF THE ISLAND AND THE EXTREME
SOUTHWEST. THE GFS SHOWS A BREAK IN THE HEAVY PRECIPITATION...BUT WE
SEEM TO RE-ENTER ANOTHER WET PERIOD ON THURSDAY OF NEXT WEEK. AT
THAT TIME THE SUB TROPICAL JET IS AGAIN POSITIONED JUST TO OUR NORTH
AND AN AREA OF FAVORABLE DIVERGENCE HOVERS JUST SOUTH OF US.  SNELL

&&

.PREV DISCUSSION...
OVERALL SHOWER ACTIVITY WAS MUCH LESS THAN EXPECTED THIS AFTERNOON.
LOOKING AT SOUNDING AND MODEL DATA...SHOWS NORTH TO NORTHEAST FLOW
AT LOW TO MID LEVELS PULLING IN DRIER AIR TO THE LOCAL AREA. HIGH
CLOUDS REMAIN IN ABUNDANCE SO OVERALL CLOUDY DAY WITH ISOLATED TO
SCATTERED SHOWERS AROUND.

WINDS SHIFT TONIGHT INTO TOMORROW TO MORE SOUTHEAST ONCE AGAIN
INCREASING MOISTURE ACROSS THE AREA. LOOKS LIKE WORST WEATHER WILL
OCCUR OVER SE COASTAL WATERS OVERNIGHT...BUT BEST POSSIBILITY FOR
SHOWERS AND FLOODING POTENTIAL FOR OVERNIGHT FRIDAY INTO
SATURDAY...ESPECIALLY ACROSS THE ST CROIX AREA.

GOOD TROUGHINESS AT MID LEVELS AS WELL AS ASSOCIATED VORT MAX
MOVING THROUGH THIS EVENING INTO TONIGHT WHICH SHOULD FUEL THE
INSTABILITY ACROSS THE AREA...BUT AT UPPER LEVELS...JET ENERGY WILL
DIMINISH AND OVERALL DYNAMICS WILL DIMINISH OVER THE NEXT FEW DAYS
BRINGING US BACK TO MORE NORMAL WEATHER BY MONDAY. RG

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN JUAN PR
610 AM AST FRI MAY 14 2004

PRZ001>013-AMZ710>750-151000-
610 AM AST FRI MAY 14 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO.

.TODAY...THE LOCAL AIRMASS STILL MOIST AND UNSTABLE. RAINFALL
AMOUNTS EVEN IN SMALL QUANTITIES MAY BE SIGNIFICANT SINCE SOILS ARE
VERY SATURATED ESPECIALLY OVER THE NORTH HALF. RIVERS AND STREAMS
LEVELS ARE VERY HIGH AND THESE WILL FLOOD WITH LESSER AMOUNTS OF
RAIN OVER THEIR BASINS. LANDSLIDES ARE LIKELY OVER STEEP TERRAIN.

MARINE CONDITIONS WILL CONTINUE ROUGH AND CHOPPY ALONG OFF SHORE
ATLANTIC WATERS. ELSEWHERE SMALL CRAFT SHOULD EXERCISE CAUTION
ELSEWHERE EXCEPT THE WEST WATERS.

.SPOTTER CALL TO ACTION STATEMENT...
SPOTTER ACTIVATION MAY BE REQUIRED.

.DAYS TWO THROUGH SEVEN...

ALTHOUGH THE POTENTIAL FOR HEAVY PRECIPITATION AND CHANCES FOR FLASH
FLOODING WILL REMAIN HIGH THROUGH THE WEEK SATURDAY COULD BE THE
MOST SIGNIFICANT DAY AND THE PRECIPITATION MAY BE EXTREME MAINLY
OVER VIEQUES...CULEBRA AND THE EAST HALF OF PUERTO RICO. WEATHER
THIS DAY WILL BE SEVERE. LANDSLIDES ARE LIKELY OVER STEEP TERRAIN.

A MODERATE TO FRESH WIND FLOW AND CHOPPY SEAS WILL PREVAIL ACROSS
THE LOCAL WATERS THROUGH NEXT WEEK.

VIZ001-002-AMZ710>730-151000-
610 AM AST FRI MAY 14 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE U.S. VIRGIN ISLANDS.

.TODAY...CONTINUOUS MODERATE TO HEAVY PASSING SHOWERS WILL LEAD TO
URBAN FLOODING AND POSSIBLE FLASH FLOODING.

.SPOTTER CALL TO ACTION STATEMENT...
SPOTTER ACTIVATION IS NOT ANTICIPATED.

.DAYS TWO THROUGH SEVEN...

CHANCES FOR PRECIPITATION WILL REMAIN HIGH BUT FROM EARLY SATURDAY
TO EVENING THE PRECIPITATION MAY BE VERY HEAVY PRODUCING HIGHER
CHANCES FOR FLASH FLOODING.

STAY TUNED TO NOAA WEATHER RADIO AND OTHER LOCAL MEDIA FOR FURTHER
DETAILS OR UPDATES.

FOR ADDITIONAL INFORMATION...VISIT THE NATIONAL WEATHER SERVICE WEB
SITE FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS AT (ALL LOWERCASE
LETTERS): HTTP://WWW.SRH.NOAA.GOV/SJU.

RIVERA