Caribbean - Central America Weather

[Gustywind]

[cycloneye]

Good morning Gustywind and the rest.To make it more easy to find and to have all the latest information about what is going on with the Soufriere Volcano,I have created a thread at the Geology sub-forum at Global weather forum for the members to post all about the Soufriere Volcano there and leave this big tent thread only to discuss about all things Weatherwise.

Link to Soufriere Volcano thread at Geology sub-forum.

viewtopic.php?f=67&t=107244&p=1952610#p1952610

[msbee]

good morning Luis
thanks for making the separate thread about the volcano.
I have just posted something there as currently St. Maarten is experiencing hazy skies which I believe is from the volcano.


Barbara

[cycloneye]

Yes,is ash over St Maarten as the web cam shows.

By the way,the members can make a mini tour of the Caribbean and Centralamerica by going to the first post of this thread and see the many radars and web cams there.

[msbee]

that web cam shot really does show the haze..
and it is a lot of fun to check out all the Caribbean and SA web cams you have listed.
thanks
Barbara

[cycloneye]

Macrocane,there is ample moisture with the front and trough combined in a good chunk of Centralamerica and it feeds from the Pacific.

[cycloneye]

This is one of the most detailed discussions from the San Juan NWS that I have seen and it looks like a rather wet Christmas day for the NE Caribbean as the cold front moves thru.

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

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
307 PM AST SUN DEC 20 2009

.SYNOPSIS...AT UPPER LEVELS...HIGH PRESSURE REMAINS OVER SOUTH AMERICA
DURING THE PERIOD. A SHORT WAVE TROUGH TO THE WEST MOVES PAST THE
AREA AND PULLS A MODEST JET OVER PUERTO RICO AND THE U.S. VIRGIN
ISLANDS ON THURSDAY. A WEAK JET WILL REMAIN OVER THE AREA UNTIL
SATURDAY. HIGH PRESSURE WILL THEN KEEP MIGRATING TROUGHS AT MID
LATITUDES NORTH OF THE LOCAL AREA.

AT MID LEVELS...HIGH PRESSURE OVER THE NORTHERN LEEWARD ISLANDS
WILL DRIFT EAST INTO THE TROPICAL ATLANTIC NOW THROUGH
THURSDAY...BUT THE RIDGE OVER THE SOUTHERN CARIBBEAN WILL BE
STRONG ENOUGH TO KEEP THE SHORT WAVE TROUGHS NORTH OF THE AREA
THROUGH 29 DEC.

AT LOWER LEVELS...LOW PRESSURE MOVING NORTHEAST OFF THE
NORTHEASTERN UNITED STATES WILL KEEP A WEAK TROUGHINESS AND LIGHT
GRADIENTS OVER THE AREA FOR THE NEXT SEVERAL DAYS. LOW PRESSURE
WILL DEVELOP IN THE CARIBBEAN SOUTH OF CUBA AND DRIFT NORTHEAST
TUESDAY THROUGH THURSDAY. THIS WILL ALLOW A FRONTAL BOUNDARY TO
DEVELOP BETWEEN THE AIR MOVING OUT OF THE WESTERN ATLANTIC AND
THE MORE MOIST AIR IN THE CARIBBEAN. THIS LOW WILL PULL NORTHEAST
OF THE AREA ON THURSDAY AND ALLOW THE FRONT TO STALL NORTH OF OR
OVER PUERTO RICO AND THE U.S. VIRGIN ISLANDS. THE BOUNDARY IS
EXPECTED TO RETURN THROUGH THE AREA ON FRIDAY NIGHT BRINGING
ANOTHER CHANCE FOR SHOWERS. AFTER WHICH THE WEATHER RETURNS TO
INTERMITTENT PERIODS OF LIGHT SHOWERS IN EAST OR NORTHEAST FLOW.

&&

.DISCUSSION...SOUTHEAST FLOW BROUGHT A FEW SHOWERS TO THE SOUTHEAST
COAST...BUT NONE WERE NOTED ELSEWHERE IN PUERTO RICO. SOME MORE
VIGOROUS SHOWERS DEVELOPED NORTH OF SAINT CROIX AND MOVED TOWARD
SAINT THOMAS DURING THE MID AFTERNOON. THE AIR MASS HAS BEEN
RELATIVELY DRY WITH PRECIPITABLE WATER VALUES BELOW 1.5 INCHES.
BOTH THE GFS AND THE NAM SHOW THE FRONTAL BOUNDARY TO THE
NORTHWEST. THEY BRING IT CLOSE...BUT SOUTHERLY FLOW PREVAILS AND
KEEPS THE FRONT NORTH OF THE AREA NOW THROUGH WEDNESDAY NIGHT. ON
WEDNESDAY NIGHT THE CONVERGENCE OVER THE AREA DUE TO THE
APPROACHING FRONTAL BAND BEGINS TO CREATE ENOUGH DYNAMICS TO
INCREASE THE SHOWER CHANCES AND SOUTHERLY FLOW KEEPS RAIN OVER THE
SOUTHEAST COAST AND THE CENTRAL AREA RECEIVES SHOWERS DURING THE
DAYTIME HOURS THURSDAY. CURRENTLY MODELS SHOW WINDS SWITCHING FROM
A SOUTHERLY COMPONENT TO A NORTHERLY COMPONENT AND THE RAIN SHIFTS
FROM FAVORING THE SOUTHERLY COAST TO FAVORING THE NORTHERN COAST.
THIS IS OPPOSITE FROM THE PATTERN NORMALLY EXPECTED DURING THE
SUMMERTIME WHEN SHOWERS FORM DUE TO CONVERGENCE ON THE OPPOSITE
SIDE OF THE ISLAND. EXPECT TO SEE MORE OROGRAPHIC LIFTING AND LESS
INFLUENCE FROM THE CONVERGENCE DURING THESE FRONTAL PASSAGES. ON
FRIDAY THE FRONT WILL PASS FROM THE NORTHEAST..IF THE FLOW FROM
THE NORTHEAST IS STRONG ENOUGH AS MODELS INDICATE. SHOWERS BECOME
MORE PROBABLY AT THIS TIME THROUGH FRIDAY NIGHT. POPS DIMINISH TO
A DRIER LEVEL CONSISTENT WITH THE CURRENT DECEMBER TREND THIS YEAR
FOR THE REST OF THE YEAR AS MOISTURE COMES IN BANDS AND FLOW IS
MOSTLY EASTERLY OR NORTHEASTERLY.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED ACROSS ALL TAF SITES
THROUGH 21/22Z. WINDS WILL REMAIN SOUTHERLY DURING THIS TIME. AN
APPROACHING FRONT SHOULD KEEP THE AREA UNDER GENERAL SUBSIDENCE
AND KEEP MOST CONVECTION SUPPRESSED TONIGHT AND MONDAY.


&&

.MARINE...SEAS ARE COMING DOWN AND WILL REMAIN BELOW SMALL CRAFT
ADVISORY CONDITIONS UNTIL TUESDAY NIGHT WHEN ANOTHER SET OF SWELLS
COME IN.

[Macrocane]

Sorry, I was out the whole day, I went to Ataco a village in the mountains in the west, it was very cold, cloudy and rainy in there. Here in San Salvador wind are not as strong a expected but it is raining and it feels cooler than the last few days. As cycloneye said there is plenty of moisture moving from the Pacific, and when it interacts with the cooler airmass behind the front we have this unnusual december rain combined with the usual northerly winds. Here is today's advisory:

Precipitaciones y vientos nortes

Translation:

Description
An upper level trough will allow the entry of moisture from the Pacific ocean generating moderate to strong showers, the high pressure system has weakened and will produce weak to moderate northerly winds.

Forecast
Sunday december 20: the skies will be cloudy to partly cloudy with scattered showers and thunderstorms (occasionally strong). The precipitations will be in diurnal and nocturnal hours especially in the mountainous and volcanic areas. The winds will come from the north with an intensity of 10-20 km/h and occasionally 30 km/h.

Monday december 21: partly cloudy to cloudy skies with scattered showers and moderate to strong thunderstorms with emphasis in the higher areas of the country the wind will come from the north and northeast, the velocities will be 10 to 30 km/h with 35-40 km/h gusts. The temperatures will be diminished on sunday and monday nights.

[cycloneye]

The rainfall deficit for December in San Juan,Puerto Rico continues to grow in negative or below normal.However,for the entire year the rainfall has been above average.Below is the latest data including December 20th.Lets see if the rain that is expected to occur by Christmas day cuts the deficit.

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          1.89 1987   0.14  -0.14     0.03
  MONTH TO DATE    1.66                      3.21  -1.55     2.27
  SINCE DEC 1      1.66                      3.21  -1.55     2.27
  SINCE JAN 1     64.69                     49.40  15.29    52.33


[Gustywind]

Good morning to you Cycloneye and the rest .

000
FXCA62 TJSJ 210848
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
448 AM AST MON DEC 21 2009

.SYNOPSIS...LIGHT WINDS AND MINIMAL SHOWER ACTIVITY ARE EXPECTED
ACROSS PUERTO RICO AND THE U.S. VIRGIN ISLANDS THROUGH THE MIDDLE
OF THE WEEK.

&&

.DISCUSSION...LATEST PROFILER DATA IS INDICATING TPW IS NEARING
ONE INCH IN SAN JUAN...AND CONTINUING TO DECLINE. WITH RIDGING ALOFT
AND A RELATIVELY DRY AIR MASS IN PLACE ACROSS THE LOWEST LAYERS
OF THE ATMOSPHERE...DO NOT EXPECT MUCH...IF ANY...SHOWER ACTIVITY
ACROSS THE LOCAL ISLANDS TODAY. HOWEVER...DUE TO THE VERY LIGHT
SYNOPTIC SCALE WIND FLOW...CANNOT RULE OUT AN ISOLATED SHOWER OR
TWO DEVELOPING OVER THE INTERIOR AND NORTHERN SECTIONS OF PUERTO
RICO THIS AFTERNOON...WITH ONLY THE SLIGHTEST CHANCE OF A SHOWER
ELSEWHERE. DO NOT EXPECT MUCH CHANGE IN THIS GENERALLY DRY WEATHER
PATTERN THROUGH THE MIDDLE OF THE WEEK...WHEN A MORE SIGNIFICANT
SURGE IN LOW LEVEL MOISTURE...ASSOCIATED WITH THE DEVELOPMENT OF A
SURFACE LOW NEAR CUBA...REACHES THE AREA. THIS SHOULD RESULT IN A FEW
MORE SHOWERS...ALBEIT NOT WIDESPREAD SHOWER ACTIVITY...ON
CHRISTMAS EVE AND CHRISTMAS DAY.

&&

.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 THROUGH MOST OF
TODAY AND TNCM THROUGH AT LEAST 211330. IN ADDITION...SOME ASH COULD
EVENTUALLY ENCROACH ON THE U.S. VIRGIN ISLANDS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 87 76 / 10 10 10 20
STT 84 76 84 76 / 10 10 10 20

&&

.SJU WATCHES/WARNINGS/ADVISORIES...

PR...NONE.
VI...NONE.

&&

$$

06/04

[Gustywind]

[Macrocane]

It's such a nice day in here! It's partly cloudy, it's windy and cold (well cold for us) I have no doubt that this december will end up being one of the wettest december in El Salvador's history it began to rain yesterday at midday and sttopped raining today at 6:00 am or so. The winds are stronger today than yesterday and with the humidity and the 17 °C (63 °F) it feels chilly. The temperrature dropped 2 °C compared to yesterday's morning and 3 °C when compared to saturday's morning. Here is today's forecast http://www.snet.gob.sv/ver/meteorologia/pronostico/24+horas/

Translation

The wind will blow from the north and northeast between 12 and 25 km/h (7.5-16 mph) with 30-40 km/h (19-25 mph) gusts, the sky will be cludy to partly cloudy with the possibility of moderate to strong scattered showers and thunderstorms with emphasis in the higher areas of the country, the day will be warm and the night cool

Extended forecast: the precipitations in the territory are caused by mid-level and upper-level patterns, they will occur today but the conditions will return to normal during tuesday

Comments about dominant systems: A weak ridge is observed in Centralamerica related to a 1024 mb high pressure over Florida producing northerly winds in the country while upper level patterns are inducing a cyclonic circulation over Guatemala and El Salvador displacing humidity from the Pacific ocean with showers and thunderstorm activity, it will feel a little warm in diurnal hours and cool in nocturnal hours.

[cycloneye]

Two new web cams are added to the growing first post of the thread radars and webcams album.One is from Virgin Gorda in the British Virgin Islands and the red phone one is from ST John in the U.S. Virgin Islands.

[Gustywind]

Two new web cams are added to the growing first post of the thread radars and webcams album.One is from Virgin Gorda in the British Virgin Islands and the red phone one is from ST John in the U.S. Virgin Islands.

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

[cycloneye]

It's such a nice day in here! It's partly cloudy, it's windy and cold (well cold for us) I have no doubt that this december will end up being one of the wettest december in El Salvador's history it began to rain yesterday at midday and sttopped raining today at 6:00 am or so. The winds are stronger today than yesterday and with the humidity and the 17 °C (63 °F) it feels chilly. The temperrature dropped 2 °C compared to yesterday's morning and 3 °C when compared to saturday's morning. Here is today's forecast http://www.snet.gob.sv/ver/meteorologia/pronostico/24+horas/

Translation

The wind will blow from the north and northeast between 12 and 25 km/h (7.5-16 mph) with 30-40 km/h (19-25 mph) gusts, the sky will be cludy to partly cloudy with the possibility of moderate to strong scattered showers and thunderstorms with emphasis in the higher areas of the country, the day will be warm and the night cool

Extended forecast: the precipitations in the territory are caused by mid-level and upper-level patterns, they will occur today but the conditions will return to normal during tuesday

Comments about dominant systems: A weak ridge is observed in Centralamerica related to a 1024 mb high pressure over Florida producing northerly winds in the country while upper level patterns are inducing a cyclonic circulation over Guatemala and El Salvador displacing humidity from the Pacific ocean with showers and thunderstorm activity, it will feel a little warm in diurnal hours and cool in nocturnal hours.

Macrocane,that is very cool for that part of the world.Do you know the lowest temperature on record in the country? In Puerto Rico,the lowest temperature was 43F in 1957 at the center of the island.

[Macrocane]

Macrocane,that is very cool for that part of the world.Do you know the lowest temperature on record in the country? In Puerto Rico,the lowest temperature was 43F in 1957 at the center of the island.

It was 3.0 °C (37 °F) in Los Naranjos a village in western El Salvador I'm not sure about the date, but on January this year the temperature in that area dropped to 3.4 °C very close to that record. Also on january 2008 a local newspaper send some reporters to El Pital (the highest mountain of the country) and they recorded 2.7 °C though it was not an official measurment.

By the way, here is the rainfall accumulations between 7:00 am yesterday and 7:00 am today: http://www.snet.gob.sv/ver/meteorologia/monitoreo/lluvia+registrada/

As you can see it rained a LOT in some places the highest amount was 98.1 mm (3.86 inches) well above the 9 mm average for the month, it's interesting to see that Puerto Rico has had below average rainfall and we have had above average. It's also interesting to note that every month of the rainy season (May-Oct) this year had below average rainfall in El Salvador but November and December (the first months of the dry seasaon) have had above average.

[cycloneye]

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.

[cycloneye]

Interesting discussion about what is expected in the long Christmas holiday weekend.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
253 PM AST MON DEC 21 2009

.SYNOPSIS...AT UPPER LEVELS...HIGH PRESSURE DOMINATES THE
CARIBBEAN. A WEAK JET MOVES OVER PUERTO RICO AND THE U.S. VIRGIN
ISLANDS ON THURSDAY FOLLOWED BY A WEAK SHORT WAVE TROUGH ON
SATURDAY.

AT MID LEVELS...HIGH PRESSURE OVER THE CARIBBEAN MOVES EAST INTO
THE TROPICAL ATLANTIC BETWEEN NOW AND THURSDAY. A WEAK SHORT WAVE
TROUGH PASSES EAST TO THE NORTH OF THE AREA THURSDAY NIGHT AND
FRIDAY. HIGH PRESSURE RE-BUILDS OVER THE CARIBBEAN ON THE WEEKEND
AND REMAINS THROUGH THE REST OF THE WEEK. MID LAYERS REMAIN DRY
EXCEPT WEDNESDAY NIGHT THROUGH THURSDAY.

AT LOWER LEVELS...A COLD FRONT LEANS OVER TOWARD THE LOCAL
AREA...BUT DOES NOT CROSS THROUGH UNTIL PERHAPS SATURDAY. LOW PRESSURE
DEVELOPS SOUTHWEST OF CUBA ON TUESDAY AND MOVES TO A POSITION
NORTH OF PUERTO RICO ON THURSDAY. THE TROUGH TRAILING THIS LOW
PASSES THROUGH PUERTO RICO AND THE U.S. VIRGIN ISLANDS THURSDAY OR
THURSDAY NIGHT. HIGH PRESSURE BUILDS OVER THE AREA FROM THE NORTH
OVER THE WEEKEND...BUT SHIFTS INTO THE CENTRAL ATLANTIC QUICKLY
WHILE WEAKENING...LEAVING MODERATE TRADE WIND FLOW IN PLACE
THROUGH THE MIDDLE OF NEXT WEEK.


&&

.DISCUSSION...FEW SHOWERS WERE SEEN TODAY AND NONE WERE SEEN OVER
LAND AS OF 3 PM AST. PRECIPITABLE WATER APPEARS TO BE BOTTOMING
OUT AND THE DRY AIR MASS SHOULD REMAIN IN FORCE AT LEAST THROUGH
WEDNESDAY. THE FRONT BEGINS TO BECOME MORE EAST-WEST NORTH OF THE
AREA AND THIS APPEARS TO REINFORCE THE SUBSIDENCE AHEAD OF THE
BOUNDARY THAT HAS YIELDED THE MOSTLY SUNNY WEATHER. ALTHOUGH THE
FRONT NEVER QUITE MAKES IT IN ON THIS ROUND...A LOW PRESSURE
DEVELOPING SOUTHWEST OF JAMAICA WILL MOVE NORTHEAST AND NORTH OF
THE AREA ON THURSDAY...COINCIDENT WITH A WEAK JET STREAK IN THE
UPPER ATMOSPHERE THAT WILL HELP DYNAMICS. THIS SHOULD YIELD SOME
SHOWERS...BUT THE ATMOSPHERIC MOISTURE IS STILL RELATIVELY SHALLOW
SO VERY HEAVY RAINS FOR ANY EXTENDED PERIOD ARE NOT EXPECTED. THE
TROUGH FROM THE LOW PASSES AND THEN THE FRONT...UNDER THE
INFLUENCE FROM ANOTHER ATLANTIC HIGH RETURNS TO THE AREA FROM THE
NORTHEAST AND WILL LIKELY PASS THROUGH ON SATURDAY. THIS MAY
BRING A FEW MORE SHOWERS FOLLOWED BY SLIGHTLY COOLER AND DRIER
WEATHER. NEVERTHELESS...THE CENTRAL ATLANTIC AIR MASS IS BY NO
MEANS DRY...SO SOME SCATTERED SHOWERS ON THE WINDWARD COASTS ARE
PROBABLE NOW THROUGH THE END OF THE FORECAST PERIOD.

&&

.AVIATION...
EXPECT PREVAILING VFR CONDITIONS ACROSS THE LOCAL
ISLANDS AND AT ALL LOCAL TAF SITES TONIGHT THROUGH TUESDAY MORNING.
VOLCANIC ASH FROM MONTSERRAT WILL CONTINUE TO IMPACT TKPK THROUGH
MOST OF TONIGHT. IN ADDITION...SOME ASH COULD EVENTUALLY ENCROACH ON
THE U.S. VIRGIN ISLANDS BEFORE TUESDAY AFTERNOON.


&&

.MARINE...THE POWERFUL STORM THAT BROUGHT BLIZZARD CONDITIONS TO
THE EAST AND NORTHEAST COASTS OF THE UNITED STATES IS NOW
AFFECTING THE NORTHERN COASTS OF PUERTO RICO AND THE U.S. VIRGIN
ISLANDS WITH SWELL THAT WILL PUSH SEA HEIGHTS TO 7 TO 9 FEET ON
THE ATLANTIC SIDE AND THE PASSAGES. SEAS IN THE CARIBBEAN ARE
RELATIVELY TRANQUIL BUT WILL BEGIN TO COME UP AFTER WINDS FROM THE
SOUTHEAST INCREASE TUESDAY AND WEDNESDAY. ANOTHER SET OF SWELL
SHOULD ARRIVE IN THE AREA ON FRIDAY NIGHT.

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

[srainhoutx]

Hope your enjoying the weather Caribbean Neighbors. Luis, you folks may want to take a peek at the HPC Extended just posted. The models have been suggesting a vigorous low pressure system for your part of the world.

[cycloneye]

Hope your enjoying the weather Caribbean Neighbors. Luis, you folks may want to take a peek at the HPC Extended just posted. The models have been suggesting a vigorous low pressure system for your part of the world.

Welcome Steve to our paradise of sort here if you go to the first post. Yes,the San Juan NWS discussions has been mentioning that low (Will pass north of the islands) indirectly will bring some rain to the NE Caribbean on the long Christmas weekend.