AFD NWS San Juan discussion about what is going on in carib

[cycloneye]

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FXCA62 TJSJ 062022
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
415 PM AST MON JUN 6 2005

.SYNOPSIS...AT UPPER LEVELS...A WEAK LOW PRESSURE IS IN THE WINDWARD
PASSAGE...OTHERWISE HIGH PRESSURE OVER SOUTH AMERICA AND THE
WINDWARD ISLANDS BUILDS WESTWARD ON TO THE EASTERN COAST OF THE
UNITED STATES FROM A CENTER SOUTH OF CUBA ON WEDNESDAY. HIGH
PRESSURE THEN MOVES WESTWARD OVER THE YUCATAN WITH A RIDGE EXTENDING
THROUGH THE CARIBBEAN BY THE BEGINNING OF NEXT WEEK. A LOW PRESSURE
IMPINGES ON THIS RIDGE NEAR THE DOMINICAN REPUBLIC FROM NORTH OF
PUERTO RICO ON SATURDAY AND MOVES THROUGH PUERTO RICO AND THE U.S.
VIRGIN ISLANDS ON TUESDAY...WEAKENING AS IT PROGRESSES.

AT MID LEVELS...HIGH PRESSURE EXTENDS FROM THE WESTERN GULF OF
MEXICO TO THE ATLANTIC EAST OF THE WINDWARD ISLANDS. BROAD HIGH
PRESSURE CONTINUES OVER THE WESTERN ATLANTIC AND EASTERN CARIBBEAN
THROUGH FRIDAY. ON SATURDAY LOW PRESSURE DEVELOPS NORTH OF PUERTO
RICO...AND REMAINS NEAR THERE UNTIL IT DISSIPATES ON MONDAY. HIGH
PRESSURE THEN RIDGES IN FROM THE EAST OVER PUERTO RICO.

AT LOWER LEVELS... LOW PRESSURE EXTENDS FROM PANAMA TO THE NORTHERN
COAST OF COLOMBIA WITH A TROUGH THAT EXTENDS ALONG THE ENTIRE NORTH
COAST OF SOUTH AMERICA. THE LOW PRESSURE MIGRATES SLOWLY EAST AND
THEN REFORMS ON WEDNESDAY JUST SOUTH OF PUERTO RICO. WEAK TROUGHING
CONTINUES IN THIS AREA THROUGH THE WEEKEND WHEN MODELS FINALLY
DEVELOP A STRONGER LOW PRESSURE SYSTEM WHICH EJECTS NORTHEAST ON
SUNDAY AND TRAVELS INTO THE WEST CENTRAL ATLANTIC.

&&

.DISCUSSION...ACTIVITY FROM THE TROPICAL WAVE CONTINUED SOUTH OF THE
FORECAST AREA TODAY. BLOW OFF FROM THE TOPS OF THESE STRONG
THUNDERSTORMS WAS EXTENSIVE AND TENDED TO COVER MOST OF THE FORECAST
AREA. THIS KEPT SURFACE HEATING TO A MINIMUM AND HENCE CONVECTIVE
ACTIVITY SO FAR HAS BEEN LIMITED TO A FEW SHOWERS MOVING WEST OVER
THE NORTHERN COASTAL PLAINS OF PUERTO RICO...SOME SHOWERS IN THE
SOUTHWEST CORNER OF THE ISLANDS AND EARLIER SHOWERS OVER THE ISLAND
OF SAINT CROIX AND THE SOUTHEAST COAST OF PUERTO RICO. ACTIVITY WAS
ALSO LIMITED BY THE PRESENCE OF DRIER MID LEVEL AIR.

A LONG STRETCH OF CONVECTIVE ACTIVITY EXTENDS FROM THE DOMINICAN
REPUBLIC SOUTHEAST TO THE WINDWARD ISLANDS. MUCH OF THIS ACTIVITY IS
FEEDING OFF THE MOISTURE LEFT FROM THE TROPICAL WAVE WHICH HAS
PASSED. THE WESTERN HALF OF THIS ACTIVITY IS RECEIVING SUPPORT FROM
THE UPPER LEVEL LOW IN THE WINDWARD PASSAGE...WHILE THE EASTERN HALF
OF THE ACTIVITY...WHICH EXTENDS EAST OF THE WINDWARD ISLANDS...MAY
BE THE RESULT OF THE CONVERGENCE AROUND THE SURFACE LOW OR TROUGH IN
THE SOUTHERN CARIBBEAN.

AS MENTIONED IN YESTERDAYS DISCUSSION...THE GFS SOLUTION IS
UNSTABLE...BUT PERHAPS NO MORE SO THAN THE WEATHER IN THE AREA. THIS
MORNING A DEFINITE MID LEVEL VORTEX NEAR 15.7 N 65.3 W APPEARED IN
SATELLITE IMAGERY...BUT IS NO LONGER WELL DEFINED. THE LATEST RUN OF
THE GFS SHOWS THE TROUGH ACROSS THE CARIBBEAN...BUT DOES NOT DEVELOP
ANY CIRCULATIONS UNTIL TUESDAY NIGHT. THIS CIRCULATION FORMS NEAR 16
N 66 W AND MOVES WEST NORTHWEST TO A POSITION SOUTH OF HISPANIOLA ON
THURSDAY. THAT IS QUITE DIFFERENT FROM THE CIRCULATION THAT WAS
PLACED OVER PUERTO RICO AT JUST A FEW HOURS EARLIER.

THE ONE THING THAT THE MODEL CONTINUES FROM RUN-TO-RUN IS THE TROUGH
OUT OF PANAMA ACROSS THE SOUTHERN CARIBBEAN AND THE SOUTHERLY FLOW
OVER THE EASTERN CARIBBEAN THAT CONTINUES AT LEAST THROUGH THE
WEEKEND. SO BELIEVE THAT THE BEST FORECAST IS ONE OF MOIST SOUTHERLY
FLOW THAT BRINGS NUMEROUS RAIN AND THUNDERSHOWERS OVER THE AREA
MAINLY FROM TUESDAY NIGHT THROUGH THURSDAY...WITH LINGERING
MOIST...CLOUDY CONDITIONS THROUGH THE WEEKEND AND SOME IMPROVEMENT
LATE IN THE FOLLOWING WEEK. ADDITIONAL LOW DEVELOPMENT OR THE
REINVIGORATION OF THE ONE SEEN THIS MORNING IS LIKELY...BUT IT COULD
OCCUR MOST ANYWHERE NEAR THE FORECAST AREA AND WOULD BE FAIRLY WEAK.
AT THIS TIME IT IS NOT BELIEVED THAT THERE IS ANY RISK OF TROPICAL
STORM FORMATION FROM THIS SYSTEM.

&&

.MARINE...MODEL WAVE GUIDANCE HAS BEGUN TO RESPOND TO THE
DEVELOPMENT OF THE LOW PRESSURE SYSTEM WHICH IS NOT LIKELY TO BE AS
INTENSE AS FORECAST. THEREFORE THE 10 FOOT SEAS FORECAST FOR THE
ATLANTIC AROUND MIDNIGHT THE MORNING OF THE 9TH WILL BE IGNORED...AS
WILL BE THE 8 FOOT SEAS FORECAST THE PREVIOUS DAY FOR THE CARIBBEAN.
OUR CURRENT FORECAST HAS NO MORE THAN 6 FEET IN THE OUTER MOST
WATERS AND THIS SHOULD BE SUFFICIENT. SEAS WILL BE CHOPPY HOWEVER...
AND THE THUNDERSTORMS WILL HAVE VERY HEAVY RAIN...GUSTY WINDS AND
LIGHTNING WHICH WILL REPRESENT LIKELY HAZARDS TO
MARINERS...ESPECIALLY IN THE CARIBBEAN TUESDAY THROUGH THURSDAY...
AND PROBABLY THE ATLANTIC WEDNESDAY THROUGH FRIDAY. CONDITIONS WERE
VERY CLOSE TO BEING SMALL CRAFT IN ALL ZONES...BUT CURRENT GRIDS
SHOW ONLY THE SOUTHEASTERN ZONE... ZONE 730...AS BEING UNDER AN
ADVISORY AND WILL LET THIS RIDE...NEARBY THUNDERSTORMS COULD EASILY
CREATE VERY LOCAL SMALL CRAFT ADVISORY CONDITIONS ANYWHERE IN THE
CARIBBEAN.

&&

.AVIATION...NUMEROUS THUNDERSTORMS WILL CONTINUE IN THE CARIBBEAN
WATERS FOR NOW...WITH MULTIPLE CLOUD LAYERS THAT WILL HAMPER
AVIATION OPERATION THERE. CONDITIONS IN THE FORECAST AREA SHOULD
REMAIN NAVIGABLE THROUGH TUESDAY...BUT ADDITIONAL SHOWERS AND
THUNDERSTORMS MAY REQUIRE WIDE CIRCUMVENTION FROM WEDNESDAY THROUGH
FRIDAY AND HIGHER TERRAIN ON THOSE DAYS WILL LIKELY BE OBSCURED.

&&

.HYDROLOGY...CURRENT MODELS SUGGEST THAT THE HEAVIEST RAINS WILL NOT
COME BEFORE TUESDAY NIGHT OR WEDNESDAY MORNING...AND WIDESPREAD
FLOODING IS NOT LIKELY BEFORE THEN. AFTERWARD THE POTENTIAL EXISTS
FOR SUFFICIENT RAIN TO CAUSE RIVERS TO LEAVE THEIR BANKS AND CAUSE
URBAN AND SMALL STREAM FLOODING...BUT THIS WILL DEPEND A GREAT DEAL
ON HOW ORGANIZED THE CONVECTION BECOMES. LOCAL WIND PATTERNS WILL
DETERMINE THE LOCATION OF THE FLOODING. THIS WILL DEPEND ON WHERE
LOWS FORM WITH RESPECT TO PUERTO RICO...WHICH AT THIS TIME CANNOT BE
DETERMINED...BUT SHOULD BE BETTER KNOWN TOMORROW.



Long discussion about all the scenarios of the Eastern Caribbean area.As I said in another thread the 12z GFS backed down on the low developing more strong north of the Leewards.But the models change run after run so let's see what occurs in the next few days but regardless what happens we are watching something early in june and that alone is always interesting.