Caribbean - Central America Weather

[cycloneye]

Good morning to all the Caribbean and Centralamerican friends.A wet Christmas eve and Christmas day is instore for the NE Caribbean thanks to the low pressure that will move north of the islands by that time.

http://forecast.weather.gov/product.php ... glossary=1

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
541 AM AST TUE DEC 22 2009

.SYNOPSIS...LIGHT WINDS AND ONLY ISOLATED SHOWERS ARE EXPECTED ACROSS
PUERTO RICO AND THE U.S. VIRGIN ISLANDS TODAY AND WEDNESDAY. AN
INCREASE IN CLOUDS AND SHOWERS ARE EXPECTED BY CHRISTMAS EVE AS AN
AREA OF LOW PRESSURE PASSES BY TO THE NORTH OF THE LOCAL ISLANDS.

&&

.DISCUSSION...EXPECT CONTINUED LIGHT WINDS...AND MINIMAL
SHOWERS...TO PERSIST ACROSS THE LOCAL ISLANDS TODAY AND
TOMORROW...AS A WEAK PRESSURE GRADIENT...STRONG CAP AND LIMITED
AVAILABLE LOW LEVEL MOISTURE CONTINUE TO BE THE DOMINANT WEATHER
DRIVERS. WOULD NOT BE SHOCKED TO SEE AN ISOLATED SHOWER OR TWO
ACROSS NORTHWESTERN SECTIONS OF PUERTO RICO THIS AFTERNOON AS
LOCAL EFFECTS WILL FAVOR THIS AREA...BUT MODELS HAVE BEEN OVER
ESTIMATING SHOWER COVERAGE THE PAST FEW DAYS SO KEPT CHANCES
RELATIVELY LOW. OVERALL...NICE WEATHER CONDITIONS...UNDER MOSTLY
SUNNY TO ONLY PARTLY CLOUDY SKIES...ARE EXPECTED FOR THE MAJORITY
OF THE FORECAST AREA TODAY AND WEDNESDAY.

EXPECT AN OVERALL CHANGE IN THE WEATHER PATTERN BY CHRISTMAS
EVE...AS AN AREA OF LOW PRESSURE DEVELOPS ACROSS THE WESTERN
CARIBBEAN...AND TRACKS NORTH OF THE LOCAL ISLANDS ON THURSDAY.
WHILE THE LOW ITSELF WILL NOT DIRECTLY IMPACT THE LOCAL
ISLANDS...A SIGNIFICANT BAND OF MOISTURE WILL GET STEERED ACROSS
THE REGION ON THURSDAY AND FRIDAY AS IT PASSES BY. THIS SHOULD
BRING A NOTICEABLE CHANGE IN CLOUD COVER AND SHOWER ACTIVITY FOR BOTH
CHRISTMAS EVE AND CHRISTMAS DAY. A RETURN TO MORE TYPICAL EASTERLY
TRADE WINDS AND WINTERTIME WEATHER IS THEN EXPECTED FOR THE
UPCOMING WEEKEND.

IN THE MEANTIME...SEVERAL BATCHES OF NORTHERLY SWELL WILL RESULT
IN ROUGH SURF CONDITIONS AS WELL AS PRESENT THE POTENTIAL FOR
DANGEROUS RIP CURRENTS...ALONG THE NORTHERN EXPOSED COASTLINES OF
THE LOCAL ISLANDS THROUGH THURSDAY. WILL CONTINUE TO MONITOR THE
BUOYS TO OUR NORTH AS A HIGH SURF ADVISORY MAY BE NECESSARY FOR
WEDNESDAY AND THURSDAY...WHEN THESE SWELLS ARE EXPECTED TO PEAK.

&&

.AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS THE LOCAL
ISLANDS AND AT ALL LOCAL TAF SITES TODAY THROUGH TONIGHT. VOLCANIC
ASH FROM MONTSERRAT WILL CONTINUE TO IMPACT TKPK OR AT LEAST ITS
VICINITY THROUGH MOST OF TODAY AND COULD ALSO AFFECT TNCM AND
EVENTUALLY THE U.S. VIRGIN ISLANDS.

&&

.MARINE...NORTHWESTERLY SWELLS ARE RAPIDLY BUILDING ACROSS THE
LOCAL ATLANTIC WATERS THIS MORNING. WENT AHEAD AN SPED UP THE
TIMING OF SMALL CRAFT ADVISORIES WITH THESE SWELLS FOR TODAY...WITH A
SECOND BATCH OF MORE NORTHERLY...AND SLIGHTLY LARGER...SWELLS
EXPECTED TO INVADE THE LOCAL WATERS ON WEDNESDAY.

[Macrocane]

Temperatures and winds:

It's a chilly morning in El Salvador, actually is the coldest morning since the cold fronts season began in mid october, I'm even wearing gloves to warm my hands. The temperature this morning was 15 °C (59 °F) in San Salvador, other locations may have even lower temps, Los Andes (a village in the mountains) for example had 7 °C (45 °F), today will be the last day for northerly winds but the nights will remain a little cool on the next few days.

Rain:

Yesterday we had little or no rain and the chances for more rain are very low though this december has been one of the wettest. Yesterday a local news show reported wich decembers were the rainiest on the last 20 years and they mentioned 1990, 1997 (record), 2004 and 2009, as you can see most of them were El Niño years.

Maybe tomorrow or the day after I will post in the winter weather the observations of this cold event, I will tell you when ready. Enjoy your weather.

[Gustywind]

Tkanks Luis, very nice webcams for the pleasure of all the carib islanders

Thanks Gusty for the words.If you or anyone has more web cams,bring them to make that first post album of cams even larger.

No problem Luis i will try if... i could find others .

[cycloneye]

Here comes the low pressure that is located in the Westcentral Caribbean.That low will cause indirectly scattered showers in the NE Caribbean on the long Christmas weekend as it moves northeastward to the north of the islands.

[cycloneye]

Wet Christmas weekend for NE Caribbean

Here is the latest discussion from HPC about the low/trough.

http://www.hpc.ncep.noaa.gov/discussions/fxca20.html

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
208 PM EST TUE DEC 22 2009

A HIGH AMPLITUDE TROUGH EXTENDS ACROSS THE
EASTERN GULF/WESTERN CARIBBEAN-NORTHERN CENTRAL AMERICA TO THE
EASTERN PACIFIC. UNDER INFLUENCE OF A STRONG SUBTROPICAL/POLAR JET
TO THE EAST OF THIS TROUGH...THE SYSTEM IS FORECAST TO SUSTAIN A
GRADUAL EASTWARD PROGRESSION DURING THE NEXT FEW DAYS. THROUGH
42-48 HRS IT IS TO MOVE ACROSS THE SOUTHEAST BAHAMAS-HAITI TO
COSTA RICA/WESTERN PANAMA. BUT AT THAT TIME...MOST OF THE SHORT
WAVE ENERGY IS FORECAST TO RAPID LIFT TO THE NORTHEAST OVER THE
SUBTROPICAL RIDGE AS IT LIES TO THE EAST. THIS WILL LEAD TO THE
GRADUAL DAMPENING OF THE TROUGH AS IT MOVES ACROSS PUERTO
RICO/NORTHEAST CARIBBEAN ISLANDS THROUGH 78-84 HRS. AT 500 HPA THE
TROUGH IS TO EXTEND INTO THE NORTHWEST CARIBBEAN/HONDURAS BY 24
HRS...AND SLOWLY MOVE INTO THE CENTRAL CARIBBEAN ALONG 75W/77W BY
48 HRS. IN TANDEM WITH THE UPPER TROUGH...IT REACHES THE NORTHEAST
CARIBBEAN ISLANDS THROUGH 72 HRS. AT LOW LEVELS...THE UPPER TROUGH
PATTERN IN INTERACTION WITH AN ELONGATED FRONT OVER THE WESTERN
CARIBBEAN SUSTAINS A CYCLONE ALONG THE MEANDERING FRONT...WITH THE
LOW TO PULL ACROSS THE CAYMAN ISLANDS INTO EASTERN CUBA THROUGH 24
HRS. THE LOW IS TO THEN PULL ACROSS THE SOUTHEAST BAHAMAS THROUGH
36-42 HRS. A SECONDARY LOW IS TO FORM SOUTH OF JAMAICA BY 24
HRS...TO ALSO PULL TO THE NORTHEAST ACROSS EASTERN CUBA/HAITI
THROUGH 48-60 HRS. AS THE LOWS PULLS AWAY...THE BAROCLINIC
BOUNDARY WILL BECOME ILL DEFINED OVER THE WESTERN
CARIBBEAN/NORTHERN CENTRAL AMERICA...TO REDEVELOP NORTH OF THE
ISLANDS LATER IN THE CYCLE.

ON THE TAIL END OF THE FRONT...ACTIVITY OVER NORTHERN
HONDURAS-BELIZE WILL GRADUALLY WANE THROUGH 36 HRS...WITH
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM. AS THE WAVE
FORMS ALONG THE FRONT OVER THE CARIBBEAN...IT WILL SUSTAIN A SURGE
IN ACTIVITY ACROSS THE CAYMAN ISLANDS-JAMAICA-EASTERN
CUBA-HAITI...WITH RAINFALL ACCUMULATION OF 20-30MM/DAY AND MAXIMA
OF 40-80MM. THROUGH 48-60 HRS THIS WILL DECREASE TO 10-20MM/DAY
AND MAXIMA OF 30-60MM. A SURGE IN ACTIVITY IS EXPECTED ACROSS THE
SOUTHEAST BAHAMAS-TURKS BY 36 HRS...WITH RAINFALL AMOUNTS OF
10-20MM/DAY AND MAXIMA OF 30-60MM/DA...AND 40-80MM/DAY AT 36-60
HRS. UNDER INFLUENCE OF THE LOW LEVEL CYCLONE...AND FAVORABLE JET
DYNAMICS...CONDITIONS ARE RIPE FOR SEVERE CONVECTION TO DEVELOP
ACROSS HAITI-JAMAICA-EASTERN CUBA AND THE SOUTHEAST BAHAMAS/TURKS.
CONDITIONS ARE LIKELY TO FAVOR WATER SPOUTS AND STRONG GUSTY
WINDS. LOCALIZED MAXIMA IN EXCESS OF 125MM ARE POSSIBLE. OVER
EASTERN HISPANIOLA INTO PUERTO RICO... EXPECT ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 20-35MM/DAY LATER IN THE CYCLE.

[cycloneye]

The deficit of rainfall for December in San Juan continues to grow.Lets see if the rain expected for the next few days cuts into that.

http://www.weather.gov/climate/getclimate.php?wfo=sju

Code: Select all

WEATHER ITEM   OBSERVED TIME   RECORD YEAR NORMAL DEPARTURE LAST
                VALUE   (LST)  VALUE       VALUE  FROM      YEAR
                                                  NORMAL
..................................................................

PRECIPITATION (IN)
  TODAY            0.00          2.72 2001   0.13  -0.13     0.04
  MONTH TO DATE    1.66                      3.47  -1.81     2.39
  SINCE DEC 1      1.66                      3.47  -1.81     2.39
  SINCE JAN 1     64.69                     49.66  15.03    52.45


[cycloneye]

Updated discussion about what to expect in the next few days as the low/trough moves north of the islands creating good upper dynamics for rather rainy conditions.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
921 PM AST TUE DEC 22 2009

http://forecast.weather.gov/product.php ... glossary=1

.UPDATE...DEEP LAYER TROUGH WITH INTENSIFYING SURFACE FEATURE
TRACKING NORTHEASTWARD OVER THE CENTRAL CARIBBEAN WILL BE MAIN
PLAYER OVER THE NEXT FEW DAYS. SATELLITE IMAGERY SHOWS IMPRESSIVE
DEEP CONVECTION NEAR THE SURFACE CENTER CURRENTLY JUST SOUTHEAST
OF JAMAICA AND RAPIDLY LIFTING NORTHEAST. ACCOMPANYING U/L TROUGH
AND RIGHT REAR QUAD OF IMPRESSIVE 250 POLAR/SUBTROPICAL JET
PROVIDING STRONG SHEAR AND DYNAMICS MORE TYPICAL OF A PROGRESSIVE
MID LATITUDE PATTERN THAN THE AVERAGE TROPICAL SURFACE LOW. AS
THIS PATTERN PROGRESSES NORTHEASTWARD...IT WILL ENCOUNTER SOME
DEGREE OF WEAKENING AND NORTHWARD DEFLECTION AROUND THE PERIPHERY
OF THE RESIDENT LOW MID TO MID LAYER RIDGE OVER THE E CARIBBEAN.
THIS SEEMS TO BE THE NUMBER ONE FACTOR PREVENTING A MORE
WIDESPREAD CONVECTIVE EVENT.

HOWEVER...ALTHOUGH A WIDESPREAD CONVECTIVE EVENT WILL BE UNLIKELY
DUE TO MID LEVEL CLOUDINESS...THERE REMAINS A DECENT CHANCE THAT
THURSDAY COULD BE A HEAVY RAIN DAY ESPECIALLY OVER THE SAN JUAN
AREA. LOW LEVEL WINDS SHOULD TURN TO THE SOUTHWEST AS THE SURFACE
FEATURE MOVES NORTH OF THE MONA PASSAGE ON THURSDAY. MID LAYER
CLOUDS SHOULD ENCOMPASS MOST OF PUERTO RICO...RESULTING IN A
MOSTLY CLOUDY DAY NEARLY EVERYWHERE. HOWEVER...SEA BREEZE WILL BE
FAVORABLE FOR CONVERGENCE OVER THE NORTHEASTERN TO NORTH CENTRAL
PORTIONS OF THE ISLAND...WHICH IF CONVECTIVE CELLS CAN OVERCOME
THE CAP...MID TO UPPER CONDITIONS WILL BE HIGHLY FAVORABLE WITH
JET STREAK OVERHEAD AND IMPRESSIVE VEERING SHEAR PROFILE (FOR THE
TROPICS) FOR DEEP CONVECTION.

SO IN SHORT...INCREASING CLOUDINESS OVER WESTERN PUERTO RICO AND
THE MONA PASSAGE WEDNESDAY WILL LEAD TO SCATTERED SHOWERS AND
MOSTLY CLOUDY SKIES THURSDAY WITH THE POSSIBILITY OF A HEAVY
THUNDERSTORM OR TWO OVER THE METRO AREA.

[cycloneye]

Good morning to all.Here is the latest discussion about what to expect with this rain event for the next couple of days.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
558 AM AST WED DEC 23 2009

.SYNOPSIS...SURFACE LOW JUST SOUTH OF HAITI OVERNIGHT...TO MOVE
ACROSS PARTS OF HAITI AND HISPANIOLA TODAY AND EARLY THURSDAY AND
CONTINUING NORTHEASTWARD ACROSS THE SOUTHERN BAHAMAS FOR THE
REMAINDER OF THURSDAY.

AN OLD FRONTAL BOUNDARY THAT EXTENDS FROM THE TROPICAL ATLANTIC
SOUTHWESTWARD TO NORTH OF THE LOCAL AREA CONTINUING ACROSS
HISPANIOLA TO MOVE NORTHEASTWARD AS SURFACE LOW (ABOVE MENTIONED)
DEEPENS ACROSS THE CENTRAL CARIBBEAN.

DEEP UPPER LEVEL TROUGH ACROSS THE WESTERN CARIBBEAN TO LIFT
NORTHEASTWARD WITHIN THE NEXT 24 TO 36 HOURS...WHILE IT CREATES
UNSTABLE WEATHER CONDITIONS FOR THE LOCAL AREA.

&&

.DISCUSSION...LATEST GFS...ECMWF-HIRES AND ECMWF LOWRES AND
NAM12...HAVE A LOW PRESSURE SYSTEM (ABOVE MENTIONED) MOVING NORTH
OF THE MONA PASSAGE AROUND 18Z ON THURSDAY...NORTH OF THE ISLANDS
AT 00Z FRIDAY...BUT THEN...THE LOW DIGS SOUTHWARD ON FRIDAY. THE
MORE AGGRESSIVE MODEL GUIDANCE WITH THIS SYSTEM IS THE
GFS...CENTERING THE LOW PRESSURE OVER PUERTO RICO SATURDAY MORNING.

THIS SCENARIO WILL BE CHALLENGING TO PIN POINT AT THIS TIME.
WEATHER SYSTEMS LIKE THOSE COULD BRING WIDESPREAD SHOWERS
ACTIVITY AND FLOODING PROBLEMS TO THE LOCAL AREA. HOWEVER...LET`S
WAIT FOR FUTURE MODEL GUIDANCE SOLUTIONS FOR A BETTER
UNDERSTANDING OF WHAT THE WEATHER CONDITIONS ARE HOLDING IN
STORAGE FOR US DURING THE UPCOMING WEEKEND.

FOR NOW...LET`S US CONCENTRATE ON THE WEATHER CONDITIONS EXPECTED
FOR THURSDAYS AS ABUNDANT MOISTURE FROM THE WEST MOVES OVER THE
LOCAL AREA.

FIRST OF ALL...UPPER LEVEL DYNAMIC ARE FAVORABLE FOR MODERATE TO
STRONG ISOLATED CONVECTION ACROSS THE LOCAL AREA ON THURSDAY
AFTERNOON/EARLY EVENING AS SHORT WAVE/TROUGH AXIS PASSES ACROSS THE
LOCAL AREA. THIS IN COMBINATION WITH LOW LEVEL MOISTURE FROM THE
EASTERN CARIBBEAN UNDER THE INFLUENCE OF A SOUTHEAST TO SOUTH WIND
LOW...TO CONVERGE ALONG THE CENTRAL INTERIOR SECTION OF THE
ISLAND...WHICH WILL RESULT IN AN ACTIVE THURSDAY AFTERNOON FOR
THOSE MUNICIPALITIES ALONG THE NORTHERN SLOPES AND NORTHERN COASTAL.

WE NEED TO MONITOR THIS WEATHER PATTERN CLOSELY DURING THE NEXT
24-30 HOURS BEFORE THE SECOND WEATHER MAKER (IF THIS MATERIALIZE)
OCCURS FOR THIS UPCOMING WEEKEND. STAY TUNED.



&&

.AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS THE LOCAL
ISLANDS AND AT ALL LOCAL TAF SITES TODAY...WITH NO SIGNIFICANT
OPERATIONAL IMPACTS ANTICIPATED. HOWEVER...DEVELOPING BANDS OF
SHOWERS AND EMBEDDED THUNDERSTORMS WILL CONTINUE TO SPREAD SLOWLY
EAST NORTHEAST ACROSS THE MONA PASSAGE AND THE NORTHWEST ATLANTIC
COASTAL WATERS OF PUERTO RICO TODAY. IN ADDITION...LEFTOVER VOLCANIC
ASH AND GAS EMISSIONS FROM SOUFRIERE HILLS IN TRPG WILL CONTINUE TO
IMPACT TKPK AND NEARBY ISLANDS UNTIL AT LEAST 231330Z. NEW EMISSIONS
APPEAR THAT THEY WILL MOVE TOWARD THE WEST NORTHWEST OR NORTHWEST
ACROSS THE CARIBBEAN WATERS AND COULD EVENTUALLY THREATEN TISX OR
ITS VICINITY LATE TODAY OR TONIGHT.


&&

.MARINE...MODERATE TO LARGE NORTHERLY SWELLS TO AFFECT THE LOCAL
AREA WATERS INCLUDING THE CARIBBEAN PASSAGES TODAY AND THURSDAY
AND ONCE AGAIN DURING THE UPCOMING WEEKEND. FOR MORE
DETAILS...READ BOTH COASTAL WEATHER FORECAST AND THE MARINE
WEATHER MESSAGE PRODUCTS.

[cycloneye]

That low pressure looks wet for Hispanola today and later for me here as the forecast says.But shear is strong to not allow this to develop.Was the bad weather a big factor in the American Airlines accident in Kingston,Jamaica?

[msbee]

It might be a rainy Christmas for some of us, but I hope you all have a Christmas filled with warmth and good cheer, no matter how the weather is.
Best wishes for a happy healthy hurricane free 2010!
Barbara

[cycloneye]

That is beautiful Barbara.Happy holidays to you and to all our Caribbean and Centralamerican friends,hoping that you get many gifts and also have a better new year in 2010 without hurricanes!

[cycloneye]

High Surf and Small Craft Advisories are up

COASTAL HAZARD MESSAGE
NATIONAL WEATHER SERVICE SAN JUAN PR
830 AM AST WED DEC 23 2009

...LONG PERIOD SWELL WILL INCREASE TODAY...

PRZ001-002-005-008-012-013-VIZ001-240030-
/O.NEW.TJSJ.SU.Y.0014.091223T1400Z-091224T1800Z/
SAN JUAN AND VICINITY-NORTHEAST-NORTH CENTRAL-NORTHWEST-CULEBRA-
VIEQUES-ST. THOMAS/ST. JOHN/ADJACENT ISLANDS-
830 AM AST WED DEC 23 2009

...HIGH SURF ADVISORY IN EFFECT UNTIL 2 PM AST THURSDAY...

THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED A HIGH SURF
ADVISORY...WHICH IS IN EFFECT UNTIL 2 PM AST THURSDAY.

A STRONG LOW IN THE ATLANTIC HAS SENT LONG PERIOD SWELL OF GREATER
THAN 7 FEET INTO THE LOCAL AREA. SEAS AT BUOY 41043 IN THE
ATLANTIC 176 MILES NORTH OF SAINT THOMAS NOW EXCEED 10 FEET. THIS
WILL PRODUCE BREAKING WAVES OF 10 TO 12 FEET IN SOME AREAS WITH
NORTHERN EXPOSURE ALONG THE COASTS OF PUERTO RICO...
CULEBRA...VIEQUES...SAINT THOMAS AND SAINT JOHN AND SMALLER
ISLANDS IN THE VICINITY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FOR THE ATLANTIC WATERS ALONG THE NORTH COASTS

...A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL LOCAL ATLANTIC WATERS
AND ALL OPEN PASSAGES...

LONG PERIOD...NORTH SWELLS WILL BEGIN TO AFFECT THE LOCAL
ATLANTIC COASTAL WATERS NO LATER THAN 10 AM AST AND LIKELY
CONTINUE OVERNIGHT AND INTO THURSDAY MORNING.

THESE LONG PERIOD SWELLS WILL PRODUCE LARGE BREAKING WAVES OF
10 TO 12 FEET OR HIGHER ALONG THE LOCAL REEFS...BEACHES AND
SHOALS OF THE LOCAL ISLANDS. THEREFORE A HIGH SURF ADVISORY HAS
BEEN ISSUED.

THESE BREAKING WAVES WILL GENERATE STRONG AND DANGEROUS CURRENTS
WITHIN THE SURF ZONE...CALLED RIP CURRENTS. THESE NARROW OUTWARD
FLOWING CURRENTS CAN CARRY PEOPLE AND ANIMALS AWAY FROM THE COAST
LINE AND OUT TO SEA. IF YOU BECOME CAUGHT IN A RIP CURRENT...DO
NOT PANIC. CALMLY...REMAIN AFLOAT...GATHER YOUR BEARINGS RELATIVE
TO THE BEACH...AND SWIM PARALLEL TO THE BEACH. YOU WILL
EVENTUALLY LEAVE THE GRIP OF THIS NARROW CURRENT...AND BE ABLE
TO SAFELY SWIM TO SHORE.

LOCAL BEACH GOERS...AND INEXPERIENCED SURFERS AND SWIMMERS ARE
URGED TO STAY OUT OF THE WATER UNTIL THESE HAZARDOUS SURF CONDITIONS
SUBSIDE. PERSONS ON THE BEACH SHOULD BE VIGILANT FOR LARGE
BREAKING WAVES SURGING UPON THE SHORE...WHICH CAN CARRY PEOPLE OF
ALL SIZES INTO THE OCEAN. YOU SHOULD AVOID BEING NEAR THE SHORE
LINE AND STAY OFF OF ROCK FORMATIONS.

THESE SURGING WAVES WILL ALSO CREATE THE POTENTIAL FOR BEACH
EROSION DURING TIMES OF HIGH TIDE.

THE HEIGHTS AND TIMES OF THE HIGH TIDE FOR THE FOLLOWING
LOCATIONS ARE:

SAN JUAN HARBOR: 1.3 FT AT 1:23 PM TODAY AND 1.1 FEET AT 2:22 AM THURSDAY.
MAGENS BAY ST THOMAS: 1.0 FEET AT 12:57 PM AST TODAY AND 1:09 PM THURSDAY.

STAY TUNED FOR ANY ADDITIONAL STATEMENTS OR POSSIBLE WATCHES OR
WARNINGS FROM YOUR NATIONAL WEATHER SERVICE FORECAST OFFICE IN
SAN JUAN.

THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGICAL AND
CLIMATE INFORMATION...IS AVAILABLE ON THE WEB AT
HTTP://WWW.SRH.NOAA.GOV/SJU OR AT HTTP://WEATHER.GOV.

&&

$$

SNELL

[cycloneye]

To keep the Caribbean members informed about what is the latest about this low pressure and trough that will affect the NE Caribbean here is the latest midday summary.

WEATHER SUMMARY FOR PUERTO RICO
NATIONAL WEATHER SERVICE SAN JUAN PR
1050 AM AST WED DEC 23 2009

PARTLY CLOUDY SKIES PREVAILED ACROSS PUERTO RICO AND CULEBRA AND
VIEQUES DURING THE MORNING HOURS. SCATTERED SHOWERS AND A FEW
THUNDERSTORMS OCCURRED MAINLY ACROSS THE FAR NORTHWEST ATLANTIC AND
ACROSS THE CARIBBEAN COASTAL WATERS. HOWEVER...THERE WAS LITTLE OR
NO RAINFALL ACTIVITY OVER LAND AREAS SO FAR THIS MORNING. THE WINDS
WERE MOSTLY FROM THE SOUTHEAST AT AROUND 10 MPH AND THE COASTAL
TEMPERATURES LATE IN THE MORNING WERE MOSTLY IN THE UPPER 80S.

THERE WILL BE A MIXTURE OF SUNSHINE AND CLOUDINESS ACROSS THE LOCAL
ISLANDS THIS AFTERNOON. ISOLATED TO LOCALLY SCATTERED SHOWERS
ARE EXPECTED OVER LAND...BUT WITH SCATTERED TO NUMEROUS SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS THE NORTHWEST ATLANTIC COASTAL WATERS
OF PUERTO RICO. HIGH TEMPERATURES WILL GENERALLY RANGE FROM THE MID
70S TO THE LOWER 80S OVER THE MOUNTAINS TO THE LOWER 80S TO AROUND
90 DEGREES ELSEWHERE. THE WIND WILL BE MAINLY SOUTHEAST AT AROUND 15
MPH OR LESS...EXCEPT FOR LOCAL SEA BREEZE VARIATIONS AT SOME COASTAL
LOCATIONS.

EXPECT INCREASING LOW LEVEL MOISTURE AND A BETTER CHANCE FOR SHOWERS
AND ISOLATED THUNDERSTORMS THURSDAY INTO FRIDAY...AS AN OLD FRONTAL
BOUNDARY SAGS SOUTH ACROSS THE LOCAL AREA AND AN UPPER LEVEL TROUGH
LIFTS NORTHEAST ACROSS THE LOCAL REGION.

ACROSS THE REGIONAL WATERS...MARINERS SHOULD EXPECT WINDS OF 15
KNOTS OR LESS AND BUILDING SEAS UP TO 9 FEET THROUGH TONIGHT. LONG
PERIOD...NORTH NORTHWEST SWELLS WILL CONTINUE TO AFFECT THE ATLANTIC
WATERS AND THE CARIBBEAN PASSAGES THIS AFTERNOON...AND WILL CONTINUE
TO BE REINFORCED BY A SECOND SURGE OF LARGER...LONG PERIOD NORTH
SWELLS THROUGH TONIGHT. THESE SWELLS WILL CONTINUE TO RESULT IN
ROUGH AND HAZARDOUS MARINE AND SURF CONDITIONS...INCLUDING RIP
CURRENTS ALONG THE NORTHWEST THROUGH NORTHEAST COASTS OF THE LOCAL
ISLANDS. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR MOST OF THE
LOCAL ATLANTIC WATERS AND THE CARIBBEAN PASSAGES THROUGH AT LEAST
THURSDAY MORNING. IN ADDITION...A HIGH SURF ADVISORY IS ALSO IN
EFFECT UNTIL 2 PM AST THURSDAY...FOR THE EXPOSED ATLANTIC COASTS.

[cycloneye]

Latest HPC discussion of Low/Trough scenario for NE Caribbean

http://www.hpc.ncep.noaa.gov/discussions/fxca20.html

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
159 PM EST WED DEC 23 2009

OVER THE CARIBBEAN...A MID/UPPER LEVEL TROUGH LIES
SOUTH ACROSS CUBA/CAYMAN ISLANDS TO COSTA RICA/WESTERN PANAMA. A
STRONG SUBTROPICAL/POLAR JET BOUND THE EASTERN PERIPHERY OF THIS
TROUGH...WHICH WILL HELP THIS FEATURE LIFT AS IT ACCELERATES
ACROSS JAMAICA/HISPANIOLA EARLY IN THE CYCLE. THROUGH 18-24 HRS
THE TROUGH IS TO MOVE ACROSS THE SOUTHEAST BAHAMAS/EASTERN
CUBA-HAITI TO PANAMA/NORTHERN COLOMBIA. BY 30-36 HRS...AS IT PULLS
INTO THE EASTERN CARIBBEAN...THE TROUGH WILL BEGIN TO WEAKEN AS
ENERGY SHEARS AROUND THE SUBTROPICAL RIDGE TO THE EAST. THIS WILL
LEAD TO THE GRADUAL DAMPENING OF THE TROUGH AS IT MOVES ACROSS
PUERTO RICO/NORTHEAST CARIBBEAN ISLANDS AND THE EROSION OF THE MID
LEVEL RIDGE PATTERN. BY 72 HRS THE UPPER FLOW OVER THE
EASTERN/CENTRAL CARIBBEAN WILL BECOME NEAR ZONAL FROM THE WEST. AT
LOW LEVELS...A LOW/CYCLONE SOUTH OF THE CAYMAN ISLANDS WILL PULL
TO THE NORTHEAST ACROSS HAITI/WINDWARD PASSAGE OF CUBA THROUGH
30-36 HRS...THEN PROPAGATE TO THE EAST ALONG AN OLD BAROCLINIC
BOUNDARY. DURING THE LAST FEW CYCLES THE GFS HAS GONE TROUGH SOME
VARIATIONS ON HOW THIS CYCLONE WAS TO EVOLVE. THE 00 UTC RUN WAS
FORECASTING THE LOW TO RETROGRESS TO PUERTO RICO/ VIRGIN ISLANDS
BY 60-84 HRS...WHILE ON THE 06UTC CYCLE IT CORRECTED IN FAVOR OF A
WEAKER PERTURBATION. THE 12 UTC GFS NO LONGER SHOWS THE LOW AFTER
36-48 HRS...FORECASTING THE LOW TO RAPIDLY SHEAR ALONG THE OLD
FRONT. BUT...AS THE AFOREMENTIONED POLAR FRONT PUSHES ACROSS THE
ATLANTIC...IT WILL MERGE WITH THE OLD BOUNDARY THROUGH 48-60 HRS.
AS THEY COMBINE...THE NEW FRONT IS TO THEN MARCH SOUTH ACROSS
PUERTO RICO/VIRGIN ISLANDS-NORTHERN LEEWARDS BY 84-96 HRS.

UNDER INFLUENCE OF THE SURFACE LOW...HEAVY RAINS ARE EXPECTED
ACROSS HAITI-DOMINICAN REPUBLIC TO THE SOUTHEAST BAHAMAS...WITH
RAINFALL AMOUNTS OF 10-20MM/DAY AND MAXIMA OF 40-80MM THROUGH 36
HRS. FURTHERMORE...UNDER FAVORABLE JET DYNAMICS...RISK OF SEVERE
CONVECTION PERSISTS...WITH SYSTEM EXPECTED TO GENERATE STRONG
GUSTY WINDS AS WELL AS LOCALIZED DOWNPOURS IN EXCESS OF 125MM IN
FEW HOURS. BY 36-60 HRS THE CONVECTION WILL CONCENTRATE ACROSS
SOUTHERN/ EASTERN HISPANIOLA-PUERTO RICO AND THE VIRGIN ISLANDS...
WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-45MM. LOCALIZED
MAXIMA OF 50-75MM ARE POSSIBLE ACROSS THE MOUNTAINS IN PUERTO
RICO. AT 48-72 HRS...CONVECTION WILL SPREAD ACROSS THE VIRGIN
ISLANDS TO THE LEEWARDS... WHERE IT IS TO SUSTAIN ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15MM. OTHER CONVECTION IS EXPECTED ALONG
THE TAIL END OF THE FRONT TO AFFECT THE BAHAMAS...WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM.

[cycloneye]

Afternoon discussion by San Juan NWS of scenario for Christmas weekend

http://forecast.weather.gov/product.php ... glossary=1

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
313 PM AST WED DEC 23 2009

.SYNOPSIS...AT MID AND UPPER LEVELS...A WEAK SHORT WAVE TROUGH
WILL PASS NORTH OF THE AREA ON THURSDAY AND AGAIN ON FRIDAY NIGHT
BEFORE HIGH PRESSURE BUILDS BACK IN OVER THE CARIBBEAN.

AT LOWER LEVELS...THE RIDGE OF HIGH PRESSURE OVER THE WESTERN
ATLANTIC WILL BECOME ORIENTED MORE TO THE NORTH AND SOUTH AS IT
MIGRATES EAST INTO THE CENTRAL ATLANTIC NOW THROUGH MONDAY. A WEAK
RIDGE WILL BUILD OVER THE ATLANTIC FROM NORTH CAROLINA TO 21 NORTH
50 WEST BY MID WEEK.

&&

.DISCUSSION...THE SATELLITE PICTURE SHOWS THAT CONVECTIVE
ACTIVITY...NOW SOUTH OF HAITI...IS SHEARED FROM THE SOUTHWEST BUT
MOVING RELATIVELY STEADILY EAST NORTHEAST ON A TRACK THAT WOULD
INTERCEPT TNCM FRIDAY IN THE EVENING IF IT WERE TO CONTINUE. IT
SHOULD PASS SOUTH OF PUERTO RICO...SPREADING MOISTURE OVER THE
AREA BEGINNING AS EARLY AS THURSDAY MORNING IN THE SOUTHWEST
PORTION OF THE AREA WITH MOISTURE SPREADING NORTHEAST OVERNIGHT
THURSDAY. MOISTURE SPREADS OVER THE U.S. VIRGIN ISLANDS BEGINNING
THURSDAY AFTERNOON...AND IS EXPECTED TO YIELD THE MOST CHANCES OF
RAIN THERE THURSDAY EVENING. AMOUNTS SHOULD NOT BE HEAVY EITHER
IN THE U.S.VI OR PR. WINDS ARE FORECAST TO SHIFT IN BOTH THE GFS
AND THE NAM FROM PREDOMINANTLY SOUTHWEST TO MAINLY NORTHEAST
FRIDAY THROUGH FRIDAY NIGHT AT WHICH TIME THE FOCUS OF SHOWER
ACTIVITY WILL SHIFT FROM THE SOUTH COAST TO THE NORTH COAST. DO
NOT EXPECT MUCH IN THE WAY OF OPPOSITE CORNER EFFECT FOR SHOWERS
WITH THIS SYSTEM...MOST OF THE ACTIVITY SHOULD BE TRIGGERED BY
TERRAIN IN AN OROGRAPHIC EFFECT. THUS SAN JUAN WILL LIKELY BE
SHELTERED FROM RAIN ON THURSDAY...THOUGH HAVE BOOSTED POPS ON
THURSDAY NIGHT JUST DUE TO OVERALL SATURATION OF THE LOWER
LAYERS. SHOWERS MUCH MORE LIKELY FRIDAY AFTERNOON AND NIGHT
NORTHEAST PORTION OF PUERTO RICO. AS HIGH PRESSURE MOVES INTO THE
ATLANTIC SUNDAY...RAIN SHOULD CLEAR OUT...THOUGH MOISTURE RETURNS
FROM THE EAST TUESDAY NIGHT.


&&

.AVIATION...VFR WILL PREVAIL THIS EVENING. SOME VA EMISSIONS
FROM SOUFRIERE HILLS IN TRPG WILL CONTINUE TO AFFECT TJSJ...TJBQ...
TISX AND TKPK UNTIL AT LEAST 23/2300Z...BUT AT THIS TIME NO
SIGNIFICANT OPERATIONAL IMPACTS ARE ANTICIPATED. NEW EMISSIONS
WILL MOVE NORTHWESTERLY ACROSS THE CARIBBEAN WATERS AND COULD
EVENTUALLY PASS OVER SOME OF THE LOCAL TAF SITES OVERNIGHT.
DEVELOPING BANDS OF SHOWERS AND EMBEDDED THUNDERSTORMS WILL
CONTINUE TO SPREAD SLOWLY EAST NORTHEAST ACROSS THE MONA PASSAGE
AND THE NORTHWEST ATLANTIC COASTAL WATERS OF PUERTO RICO LATE
TONIGHT AND TOMORROW...BRINGING PERIODS OF MVFR OR EVEN IFR
CONDITIONS ACROSS THE LOCAL TAF SITES TOMORROW AFTERNOON ALONG
WITH MOUNTAIN OBSCURATIONS.

&&

.MARINE...SWELL OF 7 TO 8 FEET WILL CONTINUE IN THE LOCAL WATERS
OVERNIGHT AND THEN BEGIN TO SUBSIDE. A NEW SET OF SWELL WILL
EMERGE ON FRIDAY NIGHT AND HEIGHTS WILL BE SIMILAR. YET ANOTHER
SET OF SWELL WILL BEGIN ON MONDAY WITH GREATER HEIGHTS LIKELY.

[cycloneye]

The long range radar shows the approaching rain comming to Puerto Rico from the southwest.

[cycloneye]

Here is the latest discussion.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
859 PM AST WED DEC 23 2009

.UPDATE...UPDATED GRIDS TO EXTEND HIGH SURF ADVISORY UNTIL 6 PM
TOMORROW EVENING. BUOY 41403 SHOWING IMPRESSIVE SWELLS OF 9 FEET
AT AROUND 13 SECONDS...WHICH SHOULD BE HITTING THE NORTHERN
COASTLINES SOMETIME OVERNIGHT. BY TOMORROW MORNING BREAKING WAVES
MAY REACH UP TO 15 ALONG REEFS AND STEEP COASTAL FEATURES.

ATMOSPHERICALLY...THE SURFACE LOW SOUTH OF HISPANIOLA IS SHOWING
THE TYPICAL NIGHT TIME CONVECTIVE BURST...WITH CLOUD TOPS COOLING
AND DEEP CONVECTION NOW EVIDENT ON RADAR ALONG WESTERN HALF OF
CWA...MOSTLY OVER WATERS. THESE CELLS WILL COME CLOSE TO THE
SOUTHERN COAST...AND MAY IMPACT SOUTHERN COASTAL LOCATIONS SUCH AS
PONCE OVERNIGHT WITH HEAVY RAIN. BY MORNING...EXPECT CONVECTION TO
DIE DOWN...LEAVING LARGE MASS OF UPPER LEVEL OUTFLOW CLOUDS OVER
THE ENTIRE CWA. THIS WILL LIKELY LIMIT DIURNAL HEATING AND
STABILIZE AIR MASS FOR THE DAY THURSDAY. NOW SEEMS MOST LIKELY THAT
WE WILL EXPERIENCE MOSTLY CLOUDY TO FULLY OVERCAST SKIES AND A FEW
POCKETS OF DRIZZLE OR LIGHT SHOWERS OVER MAINLAND PR AND NOT MUCH
ELSEWHERE. AN ISOLATED THUNDERSTORM OR TWO CANT BE OVERRULED...BUT
NOT LOOKING VERY LIKELY AT THIS TIME. AFTERWARD...SITUATION
BECOMES MORE COMPLICATED WITH A LARGE DIVERGENCE OF MODEL
SOLUTIONS...SO HAVE LEFT MID TO LONGER TERM GRIDS AS THEY WERE
CONSIDERING THE HIGH DEGREE OF ERROR ON THE 18Z CYCLE.


&&

.AVIATION...PREVAILING VFR CONDS EXPECTED ACROSS THE LOCAL TAF SITES
OVERNIGHT TONIGHT...WITH NO SIGNIFICANT OPERATIONAL IMPACTS
ANTICIPATED AT THIS MOMENT. A FEW BANDS OF SHOWERS AND EMBEDDED
TSTMS WILL DRIFT NORTHWARDS ACROSS LOCAL CARIBBEAN WATERS AND PARTS
OF THE MONA PASSAGE OVERNIGHT THROUGH THURSDAY MORNING...THIS MAY
BRING QUICK PASSING SHRA IN AND AROUND TJPS BTW 24/01Z-24/06Z AS
WELL AS ALONG THE SOUTH COASTAL SECTIONS OF PR. OTHERWISE...NO OTHER
FLYING HAZARDS EXPECTED.

[Gustywind]

Good morning to all . Here is the first discussion of the day...

000
FXCA62 TJSJ 241015
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
615 AM AST THU DEC 24 2009

.SYNOPSIS...MOSTLY CLOUDY SKIES AND ISOLATED TO SCATTERED SHOWERS
ARE EXPECTED ACROSS THE REGION TODAY AS THE LOW PRESSURE SYSTEM
NORTH OF HISPANIOLA BEGINS TO TRACK EASTWARD. CONTINUED VARIABLY CLOUDY
SKIES...WITH OCCASIONAL SHOWERS...ARE EXPECTED FOR CHRISTMAS DAY
AND THE UPCOMING WEEKEND...AS THIS LOW PASSES JUST NORTH OF THE
LOCAL ISLANDS AND THE REMNANTS OF AN OLD FRONTAL BOUNDARY PUSH
SOUTHWARD ACROSS THE REGION.

&&

.DISCUSSION...A LARGE BAND OF MOISTURE...STRETCHING FROM SOUTH
AMERICA NORTHWARD ACROSS PUERTO RICO AND INTO A LOW PRESSURE
SYSTEM NORTH OF HISPANIOLA...WILL BRING MOSTLY CLOUDY SKIES AND
ISOLATED TO SCATTERED SHOWERS ACROSS THE REGION TODAY. WHILE THERE
HAVE BEEN SOME ISOLATED THUNDERSTORMS EMBEDDED OVERNIGHT...THIS
ACTIVITY IS EXPECTED TO CONTINUE TO DIMINISH THROUGH THE MORNING
HOURS...AS SEEN IN LATEST SATELLITE IMAGERY...LEAVING ONLY VARIABLY
CLOUDY SKIES AND ISOLATED TO SCATTERED SHOWERS ACROSS THE LOCAL
ISLAND TODAY.

AS THIS CENTER OF THIS AFOREMENTIONED LOW TRACKS NEAR PUERTO RICO
OVERNIGHT TONIGHT THROUGH CHRISTMAS MORNING...EXPECT ANOTHER
UPTICK IN SHOWER ACTIVITY ACROSS THE ISLANDS...ALONG WITH SOME
ISOLATED THUNDERSTORMS. BOTH LATEST NAM AN WRF ARE INDICATING THAT
WE COULD SEE SOME MEASURABLE PRECIP OVERNIGHT...ESPECIALLY ACROSS THE
SOUTHERN AND WESTERN SECTIONS OF PUERTO RICO...SO KEPT HIGHEST
CHANCES FOR PRECIP ACROSS THESE REGIONS.

ONCE THIS LOW THEN MOVES INTO THE CENTRAL ATLANTIC...IT IS
FORECAST TO BE ABSORBED BY A MUCH LARGE LOW PRESSURE SYSTEM
WHICH...IF IT DEVELOPS...WILL BRING VERY LARGE SWELLS ACROSS THE
REGIONAL WATERS EARLY NEXT WEEK. IN THE MEANTIME...THE LARGE
SWELLS CURRENTLY AFFECTING THE LOCAL WATERS ARE FORECAST TO PEAK
BEFORE NOON TODAY...AND SLOWLY SUBSIDE THROUGH THE LATE AFTERNOON AND
EVENING HOURS. DUE TO LARGE BREAKING WAVES AND DANGEROUS RIP
CURRENTS ASSOCIATED WITH THESE SWELLS...A HIGH SURF ADVISORY REMAINS IN
EFFECT FOR THE NORTHERN EXPOSED COASTLINES OF PUERTO RICO AND THE
NORTHERN U.S. VIRGIN ISLANDS THROUGH 6 PM AST THIS EVENING.

LATE SATURDAY OR EARLY SUNDAY...COULD SEE THE REMNANTS OF AN OLD
FRONTAL BOUNDARY TO OUR NORTH GET PUSHED ACROSS THE LOCAL
ISLANDS...BRINGING ANOTHER BRIEF SURGE IN SHOWER ACTIVITY...BUT
LIKELY WILL JUST REPRESENT A RETURN TO MORE A MORE TYPICAL
WINTER LIKE WEATHER PATTERN WITH MORE TYPICAL EASTERLY TRADE
WINDS AND BANDS OF MOISTURE BRINGING OCCASIONAL SHOWERS ACROSS THE
ISLANDS FROM TIME TO TIME.

&&

.AVIATION...PREVAILING VFR CONDS EXPECTED ACROSS THE LOCAL TAF SITES
EARLY THIS MORNING...WITH NO SIGNIFICANT OPERATIONAL IMPACTS ANTICIPATED AT
THIS MOMENT. A FEW BANDS OF SHOWERS AND EMBEDDED TSTMS WILL DRIFT
NORTHEASTWARDS ACROSS THE LOCAL CARIBBEAN WATERS AND PARTS OF THE
MONA PASSAGE...WHICH WILL BRING QUICK PASSING SHRA IN AND AROUND
TJBQ...TJMZ AND TJPS BTW 24/12Z-24/18Z. OTHERWISE...NO OTHER FLYING
HAZARDS ARE ANTICIPATED FOR THE NEXT SIX TO TWELVE HOURS.

&&

.MARINE...LONG PERIOD NORTHERLY SWELLS COMBINED WITH A MODERATE TO
FRESH SOUTHWESTERLY WIND FLOW WILL CREATE ROUGH AND HAZARDOUS
MARINE CONDITIONS ACROSS THE LOCAL WATERS TODAY. A BRIEF DECREASE
IN SEAS IS EXPECTED OVERNIGHT TONIGHT AND CHRISTMAS DAY...BEFORE A
SECOND BATCH OF LARGER NORTHEASTERLY SWELLS BRING A RETURN TO
ADVISORY CONDITIONS BY SATURDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 83 74 / 20 30 30 30
STT 82 75 84 74 / 20 50 50 40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...HIGH SURF ADVISORY UNTIL 6 PM AST THIS EVENING FOR CULEBRA-NORTH
CENTRAL-NORTHEAST-NORTHWEST-SAN JUAN AND VICINITY-VIEQUES.
SCA AMZ710-712-715-722-732-741-742.

VI...HIGH SURF ADVISORY UNTIL 6 PM AST THIS EVENING FOR ST.
THOMAS/ST. JOHN/ADJACENT ISLANDS.
SCA AMZ710-712-715-722-732-741-742.

&&

$$

17/04

[Gustywind]

[cycloneye]

It looks like a good Christmas eve for last minute shopping as its not warm as the past few days with some showers but we can live with that.