Caribbean - Central America Weather

[cycloneye]

Good morning.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
453 AM AST THU OCT 4 2012

.SYNOPSIS...AT UPPER LEVELS...AN UPPER LEVEL LOW WILL MOVE TO WITHIN
430 MILES EAST NORTHEAST OF SAN JUAN BY FRIDAY AND THEN DRIFT
NORTHEAST 500 MILES BACK INTO THE ATLANTIC BY TUESDAY...EVENTUALLY
DISSIPATING IN THE SAME GENERAL AREA BY THE SATURDAY AFTER NEXT.
HIGH PRESSURE WILL DOMINATE THE LOCAL AREA SUNDAY THROUGH
THURSDAY.

AT MID LEVELS...HIGH PRESSURE IN THE WESTERN ATLANTIC WILL SHIFT
INTO THE GULF OF MEXICO BY WEDNESDAY WHILE A CUT-OFF LOW EAST
NORTHEAST OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS WILL FOLLOW
THE UPPER LEVEL LOW AND DISSIPATE INTO A WEAK TROUGH NEAR 61 WEST
THIS TIME NEXT WEEK.

AT LOWER LEVELS...HIGH PRESSURE WILL DRIFT INTO THE CAROLINAS AS A
VERY LARGE LOW PRESSURE MOVES INTO THE NORTHEAST ATLANTIC NOW
THROUGH SATURDAY. THIS LOW WILL ABSORB BOTH TROPICAL STORM NADINE
AND TROPICAL STORM OSCAR AND LEAVE A TROUGH ACROSS THE ATLANTIC
BETWEEN ITSELF AND A LOW IN THE SOUTHEASTERN CARIBBEAN. A MINOR LOBE
OF THE LARGE SURFACE LOW WILL BREAK OFF THIS FRIDAY AND MOVE
TOWARD HISPANIOLA ON SATURDAY AND CUBA ON MONDAY CAUSING A SHIFT
IN LOW LEVEL FLOW IN THE LOCAL AREA UNTIL TUESDAY. HIGH PRESSURE
AND TRADE WIND FLOW THEN ESTABLISHES ITSELF OVER THE ATLANTIC
DURING THE REST OF NEXT WEEK.

&&

.DISCUSSION...SHOWER ACTIVITY WAS LESS INTENSE THIS MORNING OVER
YESTERDAY MORNING...BUT MOST COASTAL LOCATIONS ON THE NORTH SIDE
OF PUERTO RICO RECEIVED ONE HUNDREDTH OF AN INCH OR MORE. A FEW
SHOWERS ALSO FELL IN THE WATERS JUST NORTH OF SAINT THOMAS AND
SAINT JOHN. SHOWERS WILL REDEVELOP IN SOUTHWEST PUERTO RICO IN THE
EAST NORTHEAST FLOW THIS AFTERNOON AND A FEW MAY BE QUITE HEAVY.
OVERALL THE PRECIPITATION PATTERN SHOULD BE SIMILAR TO WEDNESDAY.
ON FRIDAY THE ISLANDS BEGIN TO FEEL THE EFFECTS OF A LOBE LOW
PRESSURE THAT BREAKS OFF FROM A VERY LARGE LOW IN THE NORTHEAST
ATLANTIC AND MOVES TOWARD THE AREA. THE NAM AND THE GFS BOTH SHOW
THIS LOW...BUT THE NAM BRINGS IT SOUTH TO JUST NORTH OF PUERTO
RICO WHILE THE GFS MOVES IT TO JUST NORTH OF HISPANIOLA. THIS
BRINGS SIGNIFICANTLY DIFFERENT WIND AND RAIN PATTERNS TO THE AREA
SINCE THE NAM COVERS PUERTO RICO AND THE U.S. VIRGIN ISLANDS WITH
SOUTHWEST FLOW WHILE THE GFS BRINGS IN SOUTHEAST FLOW. THE
FORECAST WAS TAILORED TO BE CLOSER TO THE MORE MODERATE SOLUTION
OF THE GFS. THE SUBSEQUENT SOUTHEAST FLOW WILL THEN BRING IN
ADDITIONAL MOISTURE ON SUNDAY NIGHT THAT WILL AFFECT THE SOUTHEAST
COASTAL AREAS THE MOST. EXPECT THAT AFTERNOON RAINS WILL NOT SHIFT
TO THE NORTH SIDE OF THE ISLAND UNTIL AFTER FRIDAY EVEN IF THE NAM
SOLUTION VERIFIES. BEST MOISTURE WILL THEN BE ON MONDAY.
PRECIPITABLE WATER RUNS RELATIVELY HIGH...WITH BRIEF DRY SLOTS
PASSING ACROSS IN THE MOSTLY EASTERLY FLOW FOR THE REST OF THE
PERIOD. THIS WILL KEEP THE LOCAL AREA UNDER NEAR NORMAL RAINFALL...
ALTHOUGH SHOWERS IN THE U.S. VIRGIN ISLANDS WILL LIKELY NOT CARRY
MUCH IN THE WAY OF ACCUMULATIONS.

&&

.AVIATION...VFR CONDITIONS EXPECTED ACROSS THE LOCAL TERMINALS
THROUGH THE MORNING HOURS. SHRA/TSRA LIKELY ACROSS THE VICINITY OF
TJMZ AND TJPS AFTER 04/17Z...WHICH MAY CAUSE MVFR CONDITIONS AND
MOUNTAIN OBSCURATIONS ACROSS SOUTHERN AND WESTERN PUERTO RICO.
WINDS WILL INCREASE AFTER 04/12Z FROM AN EAST NORTHEASTERLY
DIRECTION WITH SEA BREEZE VARIATIONS AT 10 TO 15 KNOTS WITH HIGHER
GUSTS.

&&

.MARINE...WINDS AND SEAS WILL BEGIN TO DIMINISH AFTER TODAY AND
WILL NOT INCREASE AGAIN UNTIL LATER NEXT WEEK. SMALL CRAFT
ADVISORIES ARE NOT EXPECTED THIS WEEK OR NEXT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 87 77 / 30 40 40 50
STT 88 77 87 76 / 30 30 30 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
324 PM AST THU OCT 4 2012

.SYNOPSIS....TUTT LOW NEAR 22N58W THIS AFTERNOON WILL LINGER
NORTHEAST OF THE LOCAL REGION THROUGH THE NEXT 7 DAYS. THE TUTT LOW
WILL MOVE CLOSE TO PUERTO RICO/USVI LATE FRIDAY AND SATURDAY...INCREASING
THE RISK FOR CONVECTION. A SHORT-WAVE TROUGH WILL DIG INTO THE SW
NORTH ATLANTIC BY FRIDAY AND DEVELOP A WEAK SURFACE LOW NORTHEAST OF
PUERTO RICO BY LATE FRIDAY. A RESULTANT LOW PRESSURE WILL INDUCE A
SOUTHEASTERLY TRADE WIND FLOW ACROSS THE FORECAST AREA.

&&

.DISCUSSION...WATER VAPOR IMAGERY REVEALS A BROAD CYCLONIC CIRCULATION
ALOFT NORTHEAST OF PR/USVI ASSOCIATED WITH AN UPPER LOW/TUTT. A SHORT
WAVE TROUGH NEAR 32N61W ALSO VISIBLE IN THE WATER VAPOR IMAGERY...WILL
MOVE ALONG THE EASTERN PERIPHERY OF THE RIDGE ACROSS THE NORTHWEST
ATLANTIC INTO THE SOUTHWEST ATLANTIC. MODEL GUIDANCE SUGGESTS THAT
THIS TROUGH WILL FORM A WEAK SURFACE LOW NORTHEAST OF PUERTO RICO
BY SATURDAY. AS THE WEAK LOW DEVELOPS AND MOVES JUST NORTH OF THE
GREATER ANTILLES...SURFACE WIND FLOW WILL VEER TO THE SOUTHEAST
ON SATURDAY AND CONTINUE THROUGH THE EARLY NEXT WEEK. AS A RESULT...
DEEP MOISTURE IS EXPECTED TO POOL ACROSS THE ISLANDS FROM THE
SOUTHEAST BY THE WEEKEND. THIS HIGH MOISTURE CONTENT COMBINED WITH
GOOD VENTILATION ALOFT WILL SUSTAIN THE DEVELOPMENT OF ORGANIZED
CONVECTION ACROSS PUERTO RICO AND THE USVI...ESPECIALLY ON SUNDAY
AND MONDAY. MEANWHILE...DIURNAL PROCESSES WILL DOMINATE DURING THE
NEXT FEW OF DAYS...WITH SHOWERS AND THUNDERSTORMS DEVELOPING OVER
THE CENTRAL AND WEST SECTIONS OF PUERTO RICO IN THE AFTERNOON.

&&

.AVIATION...SCT SHRA/TSRA WILL DECR LATE AFT BUT ISOLD AND SHALLOW
CONVECTION WILL CONT INTO THE NIGHT ON NORTH AND EAST SIDE OF PR
INCLUDING USVI. PSBL MVFR WILL BE VERY BRIEF...MAINLY THIS AFTERNOON
AT TJMZ AND AN OUTSIDE CHC ELSEWHERE OVERNIGHT. LLVL WINDS TO
GENERALLY BE NE 5-15 KT THROUGH FRI.

&&

.MARINE...WINDS AND SEAS WILL GRADUALLY SUBSIDE DURING THE NEXT
DAY OR SO AND IS NOT EXPECTED TO INCREASE AGAIN UNTIL LATER NEXT
WEEK. SMALL CRAFT ADVISORIES ARE NOT EXPECTED IN THE NEXT 7 DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 87 77 88 / 30 30 30 50
STT 77 87 76 87 / 30 30 30 30

[Macrocane]

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
302 PM EDT THU OCT 04 2012

DISCUSSION FROM OCT 04/00 UTC: MEXICO CONTINUES UNDER INFLUENCE OF
STRONG MID/UPPER POLAR TROUGH. THE TROUGH IS FORECAST TO GRADUALLY
FLATTEN. AT MID LEVELS...RIDGE WILL ESTABLISH ACROSS NORTHERN
MEXICO...ENHANCING SUBSIDENCE INVERSION AND MAINTAINING CURRENT
DRY PATTERN ACROSS MOST OF THE COUNTRY. ONLY REGION WITH DEEP
MOISTURE IS THE GULF OF CAMPECHE/YUCATAN AND OAXACA/CHIAPAS.
ENHANCED LOW-LEVEL CONVERGENCE ACROSS EASTERN YUCATAN WILL
DECREASE GRADUALLY THROUGH THE CYCLE AND SO WILL THE AMOUNTS.
MOREOVER...UPPER DYNAMIC SUPPORT WILL ALSO DECREASE AS MID/UPPER
TROUGH TO THE NORTHWEST FLATTENS. ACROSS THE REGION...EXPECTING
ACCUMULATIONS OF 10-15MM/DAY AND MAXIMA OF 20-40MM/DAY THROUGH 36
HRS. ACROSS CHIAPAS/TABASCO/NORTHWEST GUATEMALA...EXPECTING
10-15MM/DAY AND MAXIMA OF 20-35MM/DAY BY 36-84 HRS. LIGHER AMOUNTS
ARE EXPECTED ACROSS YUCATAN.

ACROSS NORTHERN CENTRAL AMERICA...ACTIVE CONVECTION WILL PERSIST
ACROSS NORTHERN HONDURAS/BELIZE EARLY IN THE CYCLE ASSOCIATED WITH
EASTERLY WAVE ARRIVING INTO A REGION OF ALREADY DEEP MOISTURE.
EXPECTING ACCUMULATIONS OF 10-15MM/DAY AND MAXIMA OF 20-40MM/DAY.
LATER IN THE CYCLE...EXPECTING A DECREASE IN ACTIVITY STILL
ALLOWING DIURNAL CONVECTION TO PRODUCE ACCUMULATIONS OF
05-10MM/DAY AND MAXIMA OF 15-25MM/DAY...INCLUDING EL SALVADOR AND
MOST OF NICARAGUA BY 36-84 HRS. ACROSS WESTERN PANAMA COSTA
RICA/SOUTHERN NICARAGUA ACTIVE CONVECTION WILL DOMINATE.
DEVELOPING LOW OF PANAMA IN INTERACTION WITH WEAKENING TUTT TO THE
NORTH WILL CONTINUE FAVORING AN ACTIVE PATTERN.
INITIALLY...EXPECTING HEAVIEST ACCUMULATIONS ACROSS PANAMA
REACHING 15-20MM/DAY AND MAXIMA OF 30-60MM/DAY THROUGH 36 HRS.
LATER IN THE CYCLE...EXPECTING SIMILAR AMOUNTS EXTENDING INTO MOST
OF COSTA RICA. SIMILAR AMOUNTS ARE EXPECTED BY 60-84 HRS...WITH
MORE WIDESPREAD CONVECTION ACROSS PACIFIC REGIONS.

ACROSS THE GREATER ANTILLES...WEAK TUTT WILL PROGRESS EASTWARD
ACROSS CENTRAL CUBA INTO THE SOUTHEASTERN BAHAMAS THROUGH THE
CYCLE...WHILE A DEEP TUTT LOW APPROACHES THE LEEWARD ISLES FROM
THE NORTHEAST. ALTHOUGH TUTT WILL HELP TO VENT A FEW DIURNAL
THUNDERSTORMS...A VERY DRY AIR MASS IN PLACE AT MID-LEVELS WILL
LIMIT COVERAGE AND INTENSITY OF DIURNAL CONVECTION. MOST ACTIVE IS
EXPECTED ACROSS CUBA WITH ACCUMULATIONS OF 05-10MM/DAY AND
LOCALIZED MAXIMA OF 15-20MM/DAY. ACROSS HISPANIOLA...EXPECT AN
ACTIVATION BY 60-84 HRS AS UPPER TROUGH RETROGRESSES INTO THE
REGION IN THE PERIPHERY OF MID/UPPER RIDGE TO THE NORTH. THIS
SHORT WAVE TROUGH WILL BE ACCOMPANIED BY AN INDUCED WAVE AT
MID/LOW LEVELS AND WILL INCREASE ACCUMULATIONS TO 10-15MM/DAY AND
MAXIMA OF 20-35MM/DAY. EXPECTING ALSO AN INCREASE ACROSS THE
SOUTHEASTERN BAHAMAS TO SIMILAR AMOUNTS. PUERTO RICO WILL REMAIN
IN THE CONVERGENT SIDE OF TUTT TO THE NORTHEAST.
ACCORDINGLY...EXPECTING SHALLOW CONVECTION TO DOMINATE WITH A FEW
ISOLATED DIURNAL THUNDERSTORMS PRODUCING LIGHT AMOUNTS.

ACROSS THE WINDWARD ISLES...ACTIVE PATTERN WILL PERSIST UNDER
DESTABILIZING INFLUENCE/VENTILATION FROM TUTT-LOW TO THE NORTH.
FURTHERMORE...A TUTT-INDUCED WAVE AND POSTERIOR MOISTURE SURGE
WILL INTERACT WITH TUTT TO ENHANCE PRECIPITATION. EXPECTING
ACCUMULATIONS OF 10-15MM/DAY WITH MAXIMA OF 20-35MM/DAY THROUGH
THE CYCLE.

ACROSS COLOMBIA...ACTIVE PATTERN IS RAPIDLY ESTABLISHING AS LOW IN
GULF OF PANAMA STRENGTHENS. EXPECTING A SURGE IN CONVECTION TO
PRODUCE HEAVIEST ACCUMULATIONS ACROSS CHOCO WITH MAXIMA OF
40-80MM/DAY THROUGH 60 HRS. THESE ARE TO DECREASE TO MAXIMA OF
30-60MM/DAY LATER AS AREA OF STRONGEST FORCING PROGRESSES
NORTHWARD. ALONG THE CENTRAL/NORTHERN ANDES OF
COLOMBIA...EXPECTING AMOUNTS IN THE ORDER OF 10-15MM/DAY AND
MAXIMA OF 20-45MM/DAY...WITH HEAVIEST LIKELY BY 36-60 HRS. ACROSS
NORTHERN COLOMBIA/NORTHWESTERN VENEZUELA...EXPECTING A GRADUAL
INCREASE IN CONVECTION IN RESPONSE TO INCREASING BOUNDARY-LAYER
MOISTURE WITH ARRIVING WAVES. FURTHERMORE...INCREASED VENTILATION
FROM UPPER HIGH ESTABLISHING OVER ACTIVE COLOMBIA WILL ENHANCE
ACCUMULATIONS. EXPECTING ALSO AMOUNTS IN THE ORDER OF 10-15MM/DAY
WITH MAXIMA OF 20-45MM/DAY WITH HEAVIEST BY 36-60 HRS. ACROSS THE
SOUTHERN ANTILLES/NORTHERN COAST OF VENEZUELA...EXPECTING ACTIVE
PATTERN TO PRODUCE 05-10MM/DAY AND ISOLATED MAXIMA OF 15-20MM/DAY.

PERTURBATIONS IN THE EASTERLIES...INITIALIZED AT 12UTC...FORECAST
FROM 00UTC.

INITIAL 24 36 48 60 72 84 TYPE
57W 60W 63W 67W 69W 72W 74W TUTT INDCD
65W 68W 70W 73W 76W DSPT TW
74W DSPT TUTT INDCD
83W 86W 90W 93W DSPT EW
102W 106W 109W 111W 114W 117W 119W TUTT INDCD

A TUTT-INDUCED WAVE IS INITIALIZED AT 57W AND TO THE SOUTH OF 16N.
THIS WAVE WILL ENHANCE CONVECTION ACROSS THE LESSER ANTILLES TO
PRODUCE MAXIMUM ACUMULATIONS OF 20-35MM/DAY. THE WAVE WILL ENHANCE
THE MOISTURE TRANSPORT INTO THE SOUTHERN CARIBBEAN ENHANCING
CONVECTION. ACROSS NORTHWESTERN VENEZUELA...EXPECTING MAXIMA OF
20-45MM/DAY. ACROSS THE SOUTHERN ANTILLES EXPECTING MAXIMA OF
15-20MM/DAY.

TROPICAL WAVE INITIALIZED AT 65W AND TO THE SOUTH OF 16N WILL
ENHANCE MOISTURE TRANSPORT INTO NORTHERN COLOMBIA/NORTHWEST
VENEZUELA BEFORE DISSIPATING IN CIRCULATION ASSOCIATED WITH PANAMA
LOW. IT WILL LEAD TO MAXIMA OF 20-45MM/DAY.

THE TUTT-INDUCED WAVE ACROSS THE CENTRAL CARIBBEAN IS RAPIDLY
DISSIPATING AT 74W.

AN EASTERLY WAVE IS INITIALIZED AT 83W AND TO THE SOUTH OF 20N.
THIS WAVE WILL ENHANCE ACCUMULATIONS ACROSS NORTHERN
HONDURAS/BELIZE PRODUCING MAXIMA OF 20-40MM/DAY. ACROSS COSTA
RICA/WESTERN PANAMA...IT WILL PRODUCE MAXIMA OF 30-60MM/DAY.
ACROSS SOUTHERN GUATEMALA/EL SALVADOR/SOUTHERN HONDURAS EXPECTING
MAXIMA OF 15-25MM/DAY.

A TUTT-INDUCED WAVE IS INITIALIZED AT 102W AND TO THE SOUTH OF
15N. ALTHOUGH THIS WAVE IS ENHANCING THE NORTHWARD TRANSPORT OF
MOISTURE ACROSS THE PACIFIC COAST OF SOUTHERN MEXICO...MOIST POOL
IS FORECAST TO REMAIN OFFSHORE.

SOLANO...IMN (COSTA RICA)
ALVAREZ...ONAMET (REPUBLICA DOMINICANA)
GALVEZ...HPC (USA)

[cycloneye]

Good morning.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
525 AM AST FRI OCT 5 2012

.SYNOPSIS...TUTT LOW TO THE NORTHEAST OF THE LOCAL AREA EXPECTED
TO PREVAIL FOR THE NEXT SEVERAL DAYS. A WEAK SURFACE LOW WILL
DEVELOP LATE FRIDAY INTO SATURDAY JUST TO THE NORTHWEST OF THE
LOCAL AREA. THIS WILL MAKE THE GENERAL WIND FLOW TO SHIFT FROM THE
NORTHEAST FOR TODAY TO A LIGHT AND SOUTHEASTERLY WIND FLOW FOR
SATURDAY. THIS COMBINATION WILL INCREASE THE CHANCES OF CONVECTION
OVER PUERTO RICO ON SATURDAY...WHILE CONVECTION MAY BE MAINLY LIMITED
TO SOUTHWESTERN PUERTO RICO TODAY.

&&

.DISCUSSION...SURFACE HIGH PRESSURE TO THE NORTHWEST OF THE LOCAL
AREA IS GRADUALLY WEAKENING AND SO WILL THE NORTHEASTERLY WINDS
OVER THE LOCAL AREA TODAY. INDUCED SURFACE LOW WILL MOVE FROM THE
NORTH OF THE LOCAL AREA LATE TONIGHT TO THE NORTHWEST AND INTO
JUST NORTH OF HISPANIOLA BY LATE SATURDAY NIGHT. THIS WILL
DECREASE THE WIND SPEED OVER THE AREA SIGNIFICANTLY FOR SATURDAY
WHILE SHIFTING THE WINDS TO A SOUTHEASTERLY DIRECTION.
MEANWHILE...TUTT LOW WILL PERSIST TO THE EAST OF THE LOCAL ISLANDS.

FOR TODAY...MOISTURE WILL INCREASE WITH A NORTHEASTERLY
FLOW. PASSING SHOWERS ARE EXPECTED TO PREVAIL DURING THE MORNING
HOURS ACROSS THE LOCAL AREA. FOR THIS AFTERNOON...THUNDERSTORMS
ARE EXPECTED TO DEVELOP ACROSS THE SOUTHERN AND SOUTHWESTERN
SECTIONS OF PUERTO RICO.

FOR TOMORROW...THE COMBINATION OF AVAILABLE MOISTURE...TUTT LOW
NEAR THE AREA...SURFACE LOW NORTHWEST OF THE LOCAL AREA...AND
LOCAL EFFECTS...WILL CAUSE THE DEVELOPMENT OF SHOWERS AND
THUNDERSTORMS ACROSS CENTRAL PUERTO RICO IN THE AFTERNOON.
FORECAST SOUNDINGS INDICATE THAT THE 0-6KM STORM MOTION DECREASES
TO AS MUCH AS 1 KNOT AND THE 0-6KM AVERAGE WIND DECREASES TO 2
KNOTS FROM A WESTERLY DIRECTION FOR SATURDAY AT 18Z. THIS MAY CAUSE
PERSISTENT SHOWERS OVER ANY ONE POINT.

FOR SUNDAY INTO NEXT WEEK...AFTERNOON CONVECTION SEEMS LIKELY FOR
THE NEXT SEVERAL DAYS AS THE TUTT LOW PERSISTS CLOSE TO THE LOCAL
AREA AND THE MOISTURE REMAINS ABUNDANT. THEREFORE...PASSING
SHOWERS AFFECTING THE LOCAL ISLANDS AND WATERS ARE TO BE EXPECTED
AND AFTERNOON THUNDERSTORMS ARE LIKELY OVER PUERTO RICO.

&&

.AVIATION...VFR CONDITIONS EXPECTED ACROSS THE LOCAL TERMINALS
THROUGH THE FORECAST PERIOD. PASSING SHRA WILL BRIEFLY AFFECT
THE USVI/BVI AS WELL AS TJBQ AND TJSJ. AFTERNOON TSRA LIKELY
ACROSS SW PR...WHICH MAY AFFECT TJPS AND THE VICINITY OF TJMZ
AFTER 05/17Z...CAUSING POSSIBLE MVFR/IFR CONDITIONS. INCREASING
CLOUDINESS IN THE AFTERNOON WILL CAUSE MOUNTAIN OBSCURATIONS. WIND
WILL BE MAINLY FROM THE E-NE AT AROUND 10 KTS WITH HIGHER GUSTS
AND SEA BREEZE VARIATIONS.

&&

.MARINE...SEAS ARE CURRENTLY AROUND 5 FEET AS REPORTED
BY BUOY 41053 AND 41043. SEAS ARE EXPECTED TO GRADUALLY
DECREASE TO 3 TO 4 FEET BY LATE TONIGHT AND SATURDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 87 77 / 30 30 50 10
STT 90 75 89 76 / 30 30 30 20

[cycloneye]

Good afternoon.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
302 PM AST FRI OCT 5 2012

.SYNOPSIS...DEEP LAYERED TUTT LOW IS LOCATED JUST NORTHEAST OF THE
LEEWARD ISLANDS... WHILE BROAD/ELONGATED LONG WAVE RIDGE EXTENDS
ACROSS THE WEST AND CENTRAL ATLANTIC FROM THE NORTHWEST CARIBBEAN.
THIS PATTERN WILL PERSIST THROUGH SATURDAY...BEFORE THE UPPER LOW
BEGINS TO FILL AND PULL FURTHER NORTH OF REGION ON SUNDAY...AND
HIGH PRESSURE BUILDS OVERHEAD. IN THE LOW LEVELS...HIGH PRESSURE
RIDGE NORTH AND NORTHWEST OF THE AREA AND A DEVELOPING SURFACE LOW
NORTHEAST OF THE AREA...WILL HELP INDUCE A LIGHT TO MODERATE
NORTHEAST TRADE WIND FLOW ACROSS THE REGION THROUGH A LEAST
SATURDAY. LOCAL WINDS ARE THEN EXPECTED TO BECOME MORE SOUTHEASTERLY
BY SUNDAY AS THE DEVELOPING SURFACE LOW AND ASSOCIATED TROUGH LIFTS
WEST NORTHWEST ACROSS THE REGION.

&&

.DISCUSSION...LATEST SATELLITE IMAGERY AND UPPER AIR SOUNDINGS
ACROSS THE NORTHEAST CARIBBEAN DEPICTED SUFFICIENT LOW LEVEL MOISTURE
ADVECTION ACROSS THE REGION TO AID IN THE DEVELOPMENT OF LOCALIZED
AFTERNOON CONVECTION ACROSS PARTS OF THE ISLANDS. HOWEVER... MID
TO UPPER LEVEL PATTERN WILL PROVIDE SUBSIDENCE AND THEREFORE INHIBIT
ANY WIDESPREAD CONVECTION THROUGH SATURDAY. THE PRESENT LIGHT TO
MODERATE NORTHEAST WINDS FLOW WILL STEER MOST OF THE CONVECTION
TOWARDS PARTS OF THE SOUTHERN SLOPES AND SOUTHWEST SECTIONS OF
PUERTO RICO AND SOME OF THE VIRGIN ISLANDS WHERE AFTERNOON SHOWERS
WILL BE VERY LIMITED.

ON SATURDAY...SIMILAR CONDITIONS EXPECTED UNDER SLIGHTLY DRIER
CONDITIONS AND LIGHTER WINDS AS PREVIOUSLY MENTIONED A WEAK SURFACE
LOW LIFTS NORTHWEST ACROSS THE AREA. THE LIGHT WINDS ALONG WITH
LOCAL AND DIURNAL EFFECTS WILL AGAIN LEAD TO AFTERNOON CONVECTION
IN ISOLATED SPOTS. PERIODS OF LOCALLY HEAVY DOWNPOURS WITH MINOR
NUISANCE URBAN FLOODING WILL BE POSSIBLE IN SOME AREAS...BUT MOST
OF THE ACTIVITY WILL BE OF SHORT DURATION.

BY SUNDAY AND INTO THE EARLY PART OF NEXT WEEK...SURFACE WINDS BECOME
MORE SOUTHEASTERLY AND THE LOCAL PRESSURE GRADIENT GRADUALLY TIGHTENS.
LATEST GFS MODEL GUIDANCE SUGGESTS A SLIGHT INCREASE IN TROPICAL
MOISTURE AS AN INDUCED LOW LEVEL CONVERGENCE ZONE IS LIFTED NORTHWARDS
ACROSS THE REGION. OVERALL MOST OF THE WEEKEND SHOULD HAVE DECENT AMOUNTS
OF FAIR WEATHER CONDITIONS AS THE TUTT LOW IS NOT EXPECTED TO SHIFT
FURTHER WEST ACROSS THE REGION. THEREFORE THE AREA SHOULD REMAIN
ON THE SUBSIDENT SIDE OF THE UPPER TROUGH.

&&

.AVIATION...VFR CONDITIONS EXPECTED ACROSS ALL TAF SITES THROUGH THE
FORECAST PERIOD...EXCEPT IN TJPS WHERE SHRA/TSRA COULD PRODUCE MVFR
OR EVEN IFR CONDS THROUGH 05/22Z. NELY LLVL WINDS WILL CONTINUE THROUGH
SAT MORNING...VEERING TO THE SE LATE SAT THROUGH SUN. WIND SPEEDS WILL
BE LESS THAN 10 KTS MOST OF THE TIME.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 88 76 89 / 30 50 10 30
STT 76 88 77 88 / 30 30 20 20

[Macrocane]

Last HPC Caribbean discussion of the week:

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
215 PM EDT FRI OCT 05 2012

DISCUSSION FROM OCT 05/00 UTC: DRY AIR MASS ACROSS MOST OF MEXICO
WILL PERSIST THROUGH THE CYCLE. MID/UPPER POLAR TROUGH WILL
CONTINUE LIFTING...YET ANOTHER TROUGH IS FORECAST TO AMPLIFY TO
ITS WEST ACROSS CENTRAL MEXICO. LIMITED MOISTURE IN THIS AREA WILL
RESULT IN NO SIGNIFICANT CHANGE IN WEATHER CONDITIONS.
CONVERSELY...MOISTURE CONTINUES ENHANCED ACROSS SOUTHEASTERN
MEXICO AND WILL START RETURNING NORTHWARD ACROSS THE GULF COAST
THROUGH THE CYCLE. THIS WILL INCREASE THE CHANCES FOR
PRECIPITATION ACROSS VERACRUZ INITIALLY...AND LATER ACROSS
TAMAULIPAS. HEAVIER CELLS WILL REMAIN OFFSHORE...YET EXPECTING
SOME ACCUMULATIONS INLAND REACHING 05-10MM/DAY AND ISOLATED MAXIMA
OF 15-25MM/DAY ACROSS NORTHERN VERACRUZ/EASTERN TAMAULIPAS BY
60-84 HRS. BEST MOISTURE CONVERGENCE AND DYNAMIC FORCING WILL
CONTINUE ACROSS CHIAPAS/TABASCO/SOUTHEASTERN VERACRUZ INTO THE
GULF OF CAMPECHE. EXPECTING ACCUMULATIONS PEAKING AT 15-20MM/DAY
AND MAXIMA OF 35-70MM/DAY THROUGH 36 HRS. AMOUNTS WILL DECREASE TO
10-15MM/DAY AND LOCALIZED MAXIMA OF 20-40MM/DAY BY 36-60HRS...TI
1NCREASE AGAIN ACROSS CHIAPAS/TABASCO TO MAXIMA OF 35-70MM/DAY BY
60-84 HRS.

ACROSS NORTHERN CENTRAL AMERICA...UPPER RIDGE CENTERING OVER
BELIZE WILL GRADUALLY MEANDER SOUTHWARDS VENTILATING CONVECTION
WHERE LOW-LEVEL MOISTURE POOL REMAINS. DRIER AIR MASS IS
ESTABLISHING ACROSS THE CARIBBEAN COAST WHILE DEEPER MOISTURE POOL
IS ORGANIZING ACROSS THE PACIFIC COAST. THIS WILL LEAD TO A
DECREASE IN ACCUMULATIONS ACROSS BELIZE/CENTRAL AND EASTERN
HONDURAS/NORTHERN NICARAGUA THROUGH THE CYCLE...AND A SURGE ACROSS
EL SALVADOR/WESTERN NICARAGUA BY 36-60 HRS. BEST DYNAMIC FORCING
AND DIURNAL BREEZE CONVERGENCE WILL REMAIN ACROSS THE PACIFIC
COAST OF GUATEMALA SUSTAINING AN ACTIVE PATTERN OF
AFTERNOON/EVENING CONVECTION. INITIALLY...EXPECTING 15-20MM/DAY
WITH MAXIMA OF 35-70MM/DAY ACROSS SOUTHWESTERN GUATEMALA/SOUTHERN
CHIAPAS THROUGH 36 HRS. BY 36-60 HRS...EXPECTING 15-20MM/DAY AND
MAXIMA OF 30-60MM/DAY ACROSS THE MOUNTAINS AND PACIFIC REGION OF
GUATEMALA/EL SALVADOR/SOUTHERN HONDURAS...WITH AFTERNOON
CONVECTION OVER MOUNTAINS EVOLVING INTO COASTAL STORMS DURING THE
EVENING. ACROSS BELIZE/NORTHERN HONDURAS...EXPECTING 10-15MM/DAY
AND MAXIMA OF 20-35MM/DAY THROUGH 36 HRS DECREASING AFTERWARDS.

ACROSS SOUTHERN CENTRAL AMERICA...ACTIVE PATTERN WILL CONTINUE
ESTABLISHING IN RESPONSE TO ACTIVE LOW OF PANAMA/UPPER RIDGE
BUILDING. MODELS CONTINUE SHOWING LOW PERSISTING AND DEEP MOISTURE
POOL BUILDING UP THROUGH THE CYCLE...THE ITCZ IS ALSO FORECAST TO
SLOWLY MEANDER NORTHWARD. AT UPPER LEVELS...BUILDING RIDGE WILL
HELP VENTILATE CONVECTION. INITIALLY...EXPECTING HEAVIEST ACROSS
PANAMA/SOUTHERN COSTA RICA LEADING TO ACCUMULATIONS OF 15-20MM/DAY
AND MAXIMA OF 30-60MM/DAY THROUGH 60 HRS. HEAVY RAINFALL WILL
EXTEND INTO COSTA RICA/SOUTHERN NICARAGUA LATER LEADING TO
10-15MM/DAY AND MAXIMA OF 20-35MM/DAY BY 60-84 HRS.

ACROSS THE GREATER ANTILLES...RELATIVELY QUIET PATTERN WILL
PERSIST ACROSS JAMAICA/CUBA AS A DRY AIR MASS REMAINS IN PLACE.
EXPECTING A FEW SHOWERS AND ISOLATED STORMS TRIGGERED BY THE
DIURNAL CYCLE OF CONVECTION. TO THE EAST...A TROUGH HAS DEVELOPED
IN THE PERIPHERY OF AN UPPER RIDGE LOCATED JUST SOUTH OF BERMUDA.
THE TROUGH IS RETROGRESSING SOUTHWESTWARD AND IS INDUCING A TROUGH
AT LOW-LEVELS. SUBSIDENCE INVERSION EROSION IS ALLOWING FOR THE
DEVELOPMENT OF DEEP CONVECTION. MODELS CONTINUE SHOWING THIS
SYSTEM APPROACHING THE DOMINICAN REPUBLIC FROM THE NORTHEAST BY
36-48 HRS. STEERED BY RIDGE TO THE NORTH...THE SYSTEM WILL THEN
PROGRESS WESTWARD AND WEST-NORTHWESTWARD INTO THE SOUTHEASTERN
BAHAMAS. OVER THE DOMINICAN REPUBLIC/HAITI...EXPECTING
ACCUMULATIONS OF 10-15MM/DAY AND ISOLATED MAXIMA OF 25-50MM/DAY
THROUGH 36-84 HRS...AS BEST FORCING MIGRATES INTO HAITI BY LATE
CYCLE. ACROSS THE SOUTHEASTERN BAHAMAS/TURKS AND CAICOS EXPECTING
10-15MM/DAY AND MAXIMA OF 20-35MM/DAY DURING SAME PERIOD. ACROSS
PUERTO RICO/USVI...RATHER QUIET PATTERN WILL PERSIST THROUGH THE
CYCLE AS REGION PERSISTS IN THE CONVERGENT SECTION OF DEEP TUTT
LOW NORTHEAST OF THE LEEWARD ISLES. ALTHOUGH SUBSIDENCE INVERSION
IS WELL ESTABLISHED...EXPECTING A FEW ISOLATED CELLS IN DIURNAL
CONVECTION ACROSS THE CORDILLERA. AN INCREASE IS EXPECTED BY 60-84
HRS AHEAD OF SOUTHEASTERLY SURGE. AN INCREASE IN BOUNDARY-LAYER
MOISTURE WILL LEAD TO ACCUMULATIONS OF 10-15MM/DAY AND MAXIMA OF
15-25MM/DAY BY 60-84 HRS.

ACROSS THE LESSER ANTILLES...ACTIVE PATTERN WILL PERSIST UNDER
DESTABILIZING INFLUENCE/VENTILATION FROM DEEP TUTT-LOW TO THE
NORTH. THE TUTT HAS INDUCED A WAVE AT LOW-LEVELS THAT WILL ALSO
ENHANCE CONVECTION. MOREOVER...A BUILDING LOW-LEVEL ANTICYCLONE TO
THE EAST WILL LEAD TO A SOUTHEASTERLY SURGE IN THE TRADE WINDS
EARLY IN THE CYCLE. PLENTIFUL MOISTURE COUPLED WITH DYNAMIC
FORCING WILL LEAD TO SCATTERED CONVECTION AND A FEW THUNDERSTORMS.
EXPECTING AMOUNTS IN THE ORDER OF 10-15MM/DAY WITH MAXIMA OF
20-35MM/DAY THROUGH 60 HRS...INCREASING A MAXIMA OF 20-45MM/DAY BY
60-84 HRS...WHILE BEST FORCING SPLITS ACROSS THE LEEWARDS AND
SOUTHERN WINDWARDS.

ACROSS COLOMBIA/NORTHWEST VENEZUELA/ABC...ACTIVE PATTERN WILL
CONTINUE WITH SLIGHT DECREASE TOWARDS LATE CYCLE. AT UPPER
LEVELS...RIDGE IS BUILDING AND HELPING TO VENTILATE CONVECTION.
ACTIVE LOW OF PANAMA AND ITCZ ARE ALSO INTERACTING IN DEEP
MOISTURE POOL. BEST FORCING AND MOISTURE WILL MEANDER WESTWARD BY
LATE CYCLE SIGNIFYING A SLIGHT DECREASE BY LATE CYCLE.
INITIALLY...EXPECTING HEAVIEST ACCUMULATIONS ACROSS THE
CENTRAL/NORTHERN CHOCO AND THE NORTHERN COAST OF COLOMBIA REACHING
15-30MM/DAY AND LOCALIZED MAXIMA OF 40-80MM/DAY IN STRONGEST
CELLS. ACROSS NORTHWESTERN VENEZUELA AND THE ANDES OF COLOMBIA AND
VENEZUELA...EXPECTING 15-20MM/DAY WITH ISOLATED MAXIMA OF
25-50MM/DAY...FOLLOWING THE DIURNAL CYCLE OF CONVECTION. THIS
PATTERN WILL PERSIST THROUGH 60 HRS WHILE GRADUALLY DECREASING. BY
60-84 HRS...EXPECTING ACCUMULATIONS TO DECREASE TO 10-15MM/DAY AND
MAXIMA OF 20-35MM/DAY ACROSS MOST OF COLOMBIA WHILE SEASONABLY
ACTIVE CONVECTION PERSISTS ACROSS NORTHERN CHOCO INTO PANAMA TO
PRODUCE LOCALIZED MAXIMA OF 30-60MM/DAY.

PERTURBATIONS IN THE EASTERLIES...INITIALIZED AT 12UTC...FORECAST
FROM 00UTC.

INITIAL 24 36 48 60 72 84 TYPE
63W 65W 67W 70W 72W 74W 77W EW
69W 72W 75W DSPT TW
90W 92W DSPT EW
118W 111W 113W 115W EXITS DOMAIN TUTT INDCD/EW

THE SOUTHERN TIER OF A TUTT-INDUCED WAVE HAS BECOME IMMERSED IN
THE TRADE WINDS AND BECAME AN EASTERLY WAVE. IT IS INITIALIZED AT
63W AND TO THE SOUTH OF 14W. THIS WAVE WILL INCREASE CONVECTION
ACROSS THE NORTHERN COAST OF SOUTH AMERICA THROUGH THE CYCLE (SEE
ABOVE FOR ACCUMULATIONS). IT WILL ALSO TRANSPORT MOISTURE INTO
CENTRAL AMERICA EARLY NEXT WEEK LIKELY LEADING TO ANOTHER RAINY
SPELL EARLY NEXT WEEK.

TROPICAL WAVE INITIALIZED AT 69W AND TO THE SOUTH OF 15N IS
ENHANCING MOISTURE TRANSPORT ACROSS THE NORTHERN COAST OF SOUTH
AMERICA BUT WILL RAPIDLY WEAKEN EMBEDDED IN THE CIRCULATION
ASSOCIATED WITH PANAMA LOW. SEE ABOVE FOR ASSOCIATED ACCUMULATIONS.

AN EASTERLY WAVE AT 83W AND TO THE SOUTH OF 17N IS RAPIDLY
WEAKENING WHILE BECOMING EMBEDDED IN BROAD CIRCULATION ACROSS
EASTERN PACIFIC. THIS WAVE WILL ENHANCE ACCUMULATIONS ACROSS
BELIZE/EASTERN GUATEMALA/NORTHWESTERN HONDURAS TODAY...AS WELL AS
ACTIVATING WESTERN NICARAGUA/ EL SALVADOR AND SOUTHERN GUATEMALA
WHILE WEAKENING(SEE ABOVE FOR ACCUMULATIONS).

A TUTT-INDUCED WAVE IS INITIALIZED AT 108W AND IS EXITING THE
FORECAST DOMAIN.

SOLANO...IMN (COSTA RICA)
ALVAREZ...ONAMET (REPUBLICA DOMINICANA)
GALVEZ...HPC (USA)

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1003 PM AST FRI OCT 5 2012

.DISCUSSION...CONVECTION ONGOING WELL NORTH OF THE ISLANDS AN
INDICATOR THAT LOW LEVEL CONVERGENCE AND MAYBE A LOW IS FORMING IN
ITS VICINITY ABOUT 23N. MOST ACTIVITY IS TOO FAR FOR TJUA RADAR
BUT TOPS OF SOME THUNDERSTORMS OUT THERE SHOW UP AROUND 45 KFT OR
BETTER...BASICALLY AT TROPOPAUSE LEVEL. EXPECT BULK OF CONVECTION
TO STAY AWAY FROM THE ISLANDS EVEN THROUGH THE WEEKEND BUT SURGING
PRECIPITABLE WATER HAS REACHED 2 INCHES ON 00Z TJSJ AGAIN. THIS
WILL PROVIDE MINOR URBAN/SMALL STREAM FLOODING ON SAT PER PREVIOUS
DISCUSSION AS AFTERNOON HEAT MAXIMIZES. WINDS BECOMING VERY LIGHT
EVEN PAST 20 KFT SAT WILL PUT THE FOCUS OF THE THUNDERSTORMS OVER
THE INLAND MOUNTAINS RATHER THAN NEAR THE SOUTH COAST AS IT DID
TODAY. MIGHT NEED TO CONSIDER FLOODING MORE SINCE STORMS WILL NOT
BE PUSHED ALONG BY WINDS ALOFT. IN ANY CASE IT SHOULD NOT BE
WIDESPREAD.

[cycloneye]

Good morning.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
602 AM AST SAT OCT 6 2012

.SYNOPSIS...SURFACE LOW DEVELOPING JUST NORTH OF THE AREA WILL
MOVE TO THE SOUTHWEST TODAY AND TOMORROW. TUTT LOW TO THE
NORTHEAST OF THE LEEWARD ISLANDS IS EXPECTED TO REMAIN IN THAT
AREA THROUGH THE WEEKEND AS WELL. THIS WILL CAUSE VERY LIGHT WINDS
OVER THE LOCAL AREA. THE COMBINATION OF THIS WITH THE DIURNAL
HEATING AND SEA BREEZE CONVERGENCE WILL CAUSE SHOWERS AND
THUNDERSTORMS TO DEVELOP ACROSS THE INTERIOR AND NORTHERN SECTIONS
OF PUERTO RICO...WHILE THE LOCAL WATERS WILL OBSERVE A FEW SLOW
MOVING SHOWERS.

&&

.DISCUSSION...FORECAST SOUNDINGS INDICATE SEVERAL INTERESTING
THINGS...STARTING WITH THE FACT THAT STORM MOTION AND 0-6KM AVERAGE
WINDS WILL BE VERY LIGHT...AT AROUND 2 KNOTS FROM A WESTERLY DIRECTION
AT 06/18Z. THIS MEANS THAT ANY SHOWER THAT WERE TO DEVELOP WILL
MOVE VERY SLOWLY AND CAUSE PERSISTENT RAIN AT ANY ONE POINT.
PRECIPITABLE WATER VALUES ARE FORECAST BY THE GFS FORECAST
SOUNDINGS TO BE AROUND 1.8 INCHES...LIFTED INDEX OF -5.6 AND OTHER
INSTABILITY PARAMETERS FAVOR THUNDERSTORM POTENTIAL. IN
ADDITION...EVEN THOUGH THE WINDS ARE WEAK...THEY ARE VEERING WITH
HEIGHT...WHICH INDICATES WARM AIR ADVECTION AND PROMOTES LIFTING.
THEREFORE...IF THE MODEL GUIDANCE IS CORRECT...AND IT HAS BEEN
GOOD FOR THE PAST FEW DAYS...THUNDERSTORMS WILL LIKELY DEVELOP
ACROSS THE INTERIOR OF PUERTO RICO AND THEN SLOWLY MOVE TO THE
NORTH.

FOR TOMORROW...THE PREVAILING FLOW WILL LIKELY BE FROM THE
SOUTH...WHILE THE MOISTURE MAY INCREASE EVEN MORE...TO ABOUT 1.9
INCHES OF PRECIPITABLE WATER. WINDS WILL BE SLIGHTLY STRONGER AND
NOT VEERING WITH HEIGHT AS MUCH AS IS EXPECTED FOR TODAY. SO
SHOWERS AND THUNDERSTORMS ARE STILL EXPECTED TO DEVELOP TOMORROW
AFTERNOON...BUT MOSTLY ACROSS THE NORTHWESTERN SECTIONS OF PUERTO
RICO.

&&

.AVIATION...VFR CONDITIONS EXPECTED FOR THE LOCAL TAF SITES
TODAY. VCTS LIKELY FOR TJSJ AND POSSIBLE FOR TJPS IN THE AFTERNOON
HOURS DUE TO DEVELOPING SHRA/TSRA ACROSS THE INTERIOR OF PUERTO
RICO AND MOVING SLOWLY TO THE NORTH. WINDS WILL BE LIGHT BUT SEA
BREEZES ARE EXPECTED TO DEVELOP IN THE MORNING. SHRA/TSRA MAY
AFFECT TJSJ BUT LEFT OUT OF TAF DUE TO UNCERTAINTY.

&&

.MARINE...SEAS EXPECTED TO BE MOSTLY AT 2 TO 4 FEET TODAY WITH NO
REAL INCREASE IN SEA HEIGHT EXPECTED UNTIL TOMORROW AFTERNOON WHEN
SEAS MAY REACH 5 FEET. COASTAL WINDS ARE ALSO EXPECTED TO BE LIGHT
AND VARIABLE.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 89 78 / 40 20 30 20
STT 88 77 88 78 / 30 20 20 40

[cycloneye]

2 PM discussion of Tropical Wave in Eastern Atlantic.

TROPICAL WAVE EXTENDS FROM 09N24W TO 17N26W MOVING W AT 10-15
KT. THE WAVE IS EMBEDDED WITHIN A LOW-LEVEL MONSOON GYRE
CENTERED AT THE SOUTHERN EXTENT OF THE WAVE AXIS NEAR 09N24W AND
ALSO COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 20W-30W IN AN
AREA WEST OF THE CAPE VERDE ISLANDS. WHILE MOST DEEP CONVECTION
IS S OF 10N ASSOCIATED WITH THE MONSOON TROUGH...ISOLATED
MODERATE CONVECTION IS FROM 11N-14N BETWEEN 24W-28W.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
312 PM AST SAT OCT 6 2012

.SYNOPSIS...MID TO UPPER RIDGE NORTHWEST OF PR AND TUTT LOW JUST
NORTHEAST OF THE LESSER ANTILLES WILL LINGER NEAR THE FORECAST
THROUGH THE NEXT SEVERAL DAYS. A SURFACE LOW PRESSURE NORTH OF
BAHAMAS WILL CAUSE THE WINDS TO VEERING FROM THE SOUTHEAST ON
SUNDAY. DEEP MOISTURE WILL SURGE ACROSS THE LOCAL AREA FROM THE
SOUTHEAST SUNDAY AND MONDAY...INCREASING THE CLOUD AND SHOWER
COVERAGE ACROSS THE LOCAL ISLANDS.

&&

.DISCUSSION...A DEVELOPING SURFACE LOW ABOUT 400 MILES NORTHWEST OF
PUERTO RICO IS INDUCING A VERY LIGHT STEERING FLOW ACROSS THE NORTHEAST
CARIBBEAN ISLES. THIS LIGHT FLOW IN COMBINATION WITH AVAILABLE
MOISTURE...SEA BREEZE CONVERGENCE AND GOOD VENTILATION ALOFT WILL
CONTINUE TO PRODUCE INTENSE AND SLOW MOVING SHOWERS/THUNDERSTORMS
ACROSS INTERIOR AND EAST SECTIONS OF PR AS WELL AS PARTS OF ST.
CROIX THE REST OF THE AFTERNOON. AFTERNOON CONVECTION SHOULD TAPER
OFF BY EARLY THIS EVENING...LEAVING ONLY A FEW PASSING SHOWERS AND
MAINLY PARTLY CLOUDY SKIES FOR TONIGHT. FOR SUNDAY THROUGH EARLY
NEXT WEEK...MODELS SHOW THAT THE SURFACE LOW ACROSS THE BAHAMAS
WILL MOVE WNW OVER THE WESTERN ATLANTIC...CAUSING THE WIND DIRECTION
TO CHANGE FROM THE SOUTHEAST AND DEEPER MOISTURE TO SURGE ACROSS
THE NORTHEAST CARIBBEAN ISLANDS. OVERALL...LOOKS LIKE THE MOST
ACTIVE CONVECTION WILL OCCUR BETWEEN SUNDAY AND MONDAY...ESPECIALLY
IN THE AFTERNOON HOURS. THE NEXT TROPICAL WAVE IS FORECAST TO MOVE
ACROSS THE EASTERN CARIBBEAN FRIDAY NEXT WEEK.

&&

.AVIATION...MOSTLY VFR CONDS EXPECTED ACROSS ALL TAF SITES AND EN
ROUTE BTW ISLANDS THROUGH THE FORECAST PERIOD. HOWEVER...AT LEAST
TIL 06/23Z...ISOLD SHRA/TSRA WILL DEVELOP ACROSS THE CENTRAL MTN
RANGE OF PR. THIS MAY LEAD TO BRIEF PERIODS OF MVFR CONDS IN AND
AROUND TJSJ...TJNR...TJPS...TISX AND TIST. BRIEF MTN TOP OBSCR DUE
TO AFTN CONVECTION WILL ALSO REMAIN POSSIBLE TIL 06/23Z. LOW LEVEL
WINDS WILL REMAIN FAIRLY LIGHT AND VARIABLE BLO 200 FT.

&&

.MARINE...SEAS EXPECTED TO BE MOSTLY AT 2 TO 3 FEET TONIGHT AND
EARLY SUNDAY. MODERATE NORTHEAST SWELLS GENERATED BY A BROAD LOW
PRESSURE OVER THE CENTRAL NORTH ATLANTIC WILL INVADE THE ATLANTIC
WATERS AND CARIBBEAN PASSAGE ON SUNDAY. SWELLS WILL RANGE BETWEEN
3 TO 4 FEET WITH 12 TO 14 SECONDS. COASTAL WINDS WILL BE MAINLY LIGHT
AND VARIABLE.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 89 77 89 / 20 30 20 40
STT 76 88 78 89 / 20 20 40 40

[tropicana]

Waterspout off Choiseul, SW St Lucia at around 3:30pmET Sat Oct 6/12 ... this location is just WNW of the Hewannora International Airport in St Lucia... where winds have been light SE all day, as was much of the Eastern Caribbean, but in the hour of the reported waterspout, winds veered light westerly in association with the thunderstorm that produced this isolated spout.

[cycloneye]

The Soufriere Volcano in Montserrat has been throwing ash all day on this Saturday the 6th. You can dfollow what is going on with the Volcano at the Soufriere Volcano thread at the Geology forum.

viewtopic.php?f=67&t=107244&hilit=&p=2278952#p2278952

[cycloneye]

8 PM Discussion of Eastern Atlantic Wave.

TROPICAL WAVE EXTENDS FROM 17N28W TO 9N27W MOVING W AT 15 KT.
THE WAVE IS EMBEDDED WITHIN BROAD CYCLONIC FLOW AROUND THE
MONSOON TROUGH THAT IS CENTERED NEAR THE SOUTHERN EXTENT OF THE
WAVE WHERE A SPOT 1010 MB SURFACE LOW HAS BEEN ANALYZED. THE
WAVE LIES ON THE WESTERN SIDE OF A SURGE OF DEEP LAYER MOISTURE
PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. CONVECTION IS
CURRENTLY RESTRICTED TO THE MONSOON TROUGH REGION NEAR THE LOW
PRESSURE CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 3N-9N BETWEEN 24W-28W...AND FROM 7N-11N BETWEEN 28W-34W.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1030 PM AST SAT OCT 6 2012

.UPDATE...THE AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS CENTRAL
SECTIONS OF PUERTO RICO DISSIPATED RAPIDLY AFTER SUNSET LEAVING
PARTLY CLOUDY SKIES WITH ONLY ISOLATED SHOWERS MAINLY ACROSS THE
SURROUNDING COASTAL WATERS. THE AFTERNOON ACTIVITY WAS THE RESULT OF
DAYTIME HEATING...SEA BREEZE CONVERGENCE AND LOCAL OROGRAPHIC
EFFECTS. FOR THE OVERNIGHT HOURS ONLY ISOLATED SHOWERS ARE POSSIBLE
ACROSS EASTERN SECTIONS OF PUERTO RICO AND ACROSS THE SURROUNDING
COASTAL WATERS.

A SURFACE LOW...JUST NORTH OF HISPANIOLA WILL CONTINUE TO PRODUCE A
VERY LIGHT WIND PATTERN ACROSS THE LOCAL ISLANDS. AS THIS LOW
PRESSURE CENTER MOVES TO THE NORTHWEST...THE LOW LEVEL WIND ACROSS
THE REGION WILL CHANGE FROM THE SOUTHEAST ON SUNDAY AND MONDAY. THIS
CHANGE IN WIND DIRECTION WILL BRING DEEP TROPICAL MOISTURE ACROSS
THE REGION DURING THE NEXT FEW DAYS. THE DEEP TROPICAL MOISTURE WILL
COMBINE WITH THE STRONG DIURNAL HEATING...SEA BREEZE CONVERGENCE AND
LOCAL ISLANDS EFFECTS TO PRODUCE NEW ROUNDS OF SLOW MOVING
SHOWERS AND THUNDERSTORMS ACROSS WESTERN...INTERIOR AND NORTHWEST
SECTIONS OF PUERTO RICO DURING THE AFTERNOONS.

[cycloneye]

Good morning.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
535 AM AST SUN OCT 7 2012

.SYNOPSIS...UPPER LEVEL LOW EAST OF THE AREA...WILL MOVE AWAY FROM
THE REGION AND WEAKENING NEXT FEW DAYS. ANOTHER UPPER LEVEL
TROUGH WILL DEVELOP SOUTHWEST OF THE AREA MONDAY. AT THE
SURFACE...LOW PRESSURE SYSTEM WILL CONTINUE TO MOVE MAINLY WEST
NORTHWEST OF PUERTO RICO TODAY AND TONIGHT. A SOUTHEAST WIND FLOW
WILL PREVAIL THROUGH MONDAY NIGHT INTO TUESDAY.

&&

.DISCUSSION...SOME SHOWERS WERE OBSERVED OVER THE COASTAL
WATERS...MOVING NORTH OVERNIGHT. SOME OF THESE SHOWERS BRUSHED THE
SOUTH AND SOUTHWEST SECTIONS OF PUERTO RICO..BUT RAINFALL ACCUMULATION
WERE MINIMAL. A SOUTH TO SOUTHEAST WIND FLOW WILL CONTINUE THROUGH
AT LEAST MONDAY NIGHT INTO TUESDAY. THIS FLOW WILL CONTINUE TO
BRING DEEP TROPICAL MOISTURE AND WARM AIR ADVECTION TO OUR REGION.
IN FACT...LATEST GUIDANCE INDICATED THETA-E VALUES AT 700 MB WILL
INCREASE TO NEAR 336K BY MONDAY...WITH PW VALUES REACHING 2.0
INCHES. THIS WILL MAINTAIN ACTIVE AFTERNOONS OVER PUERTO
RICO...MAINLY ALONG THE CORDILLERA CENTRAL EACH DAY...WITH PLENTY
OF SUNSHINE DURING THE MORNING HOURS. AN UPPER LEVEL TROUGH IS
EXPECTED TO DEVELOP SOUTHWEST OF THE REGION BY TONIGHT...ENHANCING
THE DEVELOPMENT OF SHOWER AND THUNDERSTORM ACTIVITY OVER THE
REGION. WINDS ARE EXPECTED TO SHIFT MORE EASTERLY BY TUESDAY...AND
SURFACE HIGH PRESSURE RIDGE EXTENDS IN OUR AREA.

IN THE LONG RANGE...COMPUTER MODELS INDICATE A WET PATTERN WILL
ESTABLISH ACROSS THE REGION BEGINNING LATE NEXT WEEK...AS MOISTURE
FROM THE DEEP TROPICS ENCOMPASS THE REGION. IS TOO EARLY TO KNOW
IF THIS FORECAST WILL VERIFY. STAY TUNED FOR UPDATES ON THIS
WEATHER SCENARIO.

&&

.AVIATION...VFR XPTD THIS MORNING XCP SLGT CHC MVFR TJPS/TJMZ/
TIST/TISX AS SHRA MOVE ONSHORE. OTHW SCT SHRA/TSRA DVLPG IN
AFTERNOON WITH CHC MVFR CIG/VSBY. SOME MTN OBSC IN SLOWLY MOVG
CONVECTION. WINDS BLO FL200 VRBL THRU MON 10 KT OR LESS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 90 78 / 30 20 40 20
STT 88 78 89 79 / 20 40 40 30

[cycloneye]

8 AM discussion of Tropical Wave in Eastern Atlantic.

TROPICAL WAVE W OF THE CAPE VERDE ISLANDS EXTENDS FROM 17N29W
ALONG 13N30W TO A WEAK 1011 MB LOW NEAR 9N29W MOVING W NEAR 15
KT. WAVE IS EMBEDDED WITHIN A SLIGHT SURGE OF DEEP MOISTURE AS
DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 9N-11N
BETWEEN 29W-32W.

[cycloneye]

2 PM Discussion of Tropical Wave in Eastern Atlantic.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 30W/31W TO THE SOUTH
OF 17N. A 1012 MB LOW PRESSURE CENTER IS NEAR 9N ALONG THE WAVE.
THIS SURFACE CYCLONIC CIRCULATION CENTER SHOWED UP IN THE LATEST
SCATTEROMETER WIND DATA. NEARBY CONVECTIVE PRECIPITATION APPEARS
TO BE MORE RELATED TO THE MONSOON TROUGH THAN TO THE WAVE.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
350 PM AST SUN OCT 7 2012

.SYNOPSIS...TUTT/UPPER LOW NORTHEAST OF THE LESSER ANTILLES WILL
FILL AND MEANDER OVER THE TROPICAL ATLANTIC DURING THE NEXT
COUPLE OF DAYS. A SURFACE LOW PRESSURE NORTH OF BAHAMAS AND A
BUILDING RIDGE ACROSS THE NORTH CENTRAL ATLANTIC ARE INDUCING A
LONG FETCH SOUTHEASTERLY FLOW ACROSS THE EASTERN CARIBBEAN. DEEP
MOISTURE WILL CONTINUE TO SURGE ACROSS THE LOCAL AREA DURING THE
NEXT 24 HOURS...INCREASING THE CLOUD AND SHOWER COVERAGE ACROSS
THE LOCAL ISLANDS.

&&

.DISCUSSION...LATEST SURFACE ANALYSIS SHOWS A 1008 MB SURFACE LOW
CENTERED NORTH OF HISPANOLA. THIS WEAK LOW WILL LINGER ACROSS THE
SW NORTH ATLANTIC THROUGH AT LEAST WEDNESDAY. A WEAK TROUGH ALOFT
WILL FORM SOUTH OF MONA PASSAGE TONIGHT...ENHANCING THE DIVERGENCE
ALOFT ACROSS THE NORTHEAST CARIBBEAN TONIGHT AND MONDAY. SATELLITE
DERIVED BLENDED PWAT ANALYSIS INDICATES DEEP TROPICAL MOISTURE JUST
SOUTHEAST OF PUERTO RICO WITH PRECIPITABLE WATER VALUES ABOVE 2.1
INCHES. VERY MOIST SOUTHEAST FLOW COMBINED WITH AN UNSTABLE ENVIRONMENT
GENERATED BY THE PROXIMITY OF THE WEAK UPPER TROUGH WILL FUEL SHOWERS
AND THUNDERSTORMS ACROSS THE FORECAST AREA DURING THE NEXT 24 TO 36
HOURS. THE MOST ACTIVE PERIOD WILL BE MONDAY AFTERNOON.

MEDIUM AND LONG RANGE...LATEST FORECAST MODELS SUGGEST THAT THE WINDS
WILL BACK TO EAST-NORTHEAST AS THE HIGH PRESSURE RIDGE STRENGTHENS
AND SETTLES OVER THE CENTRAL NORTH ATLANTIC. AS A RESULT...TRADE WIND
WEATHER WILL RETURN TO THE LOCAL ISLANDS...WITH AFTERNOON SHOWERS FAVORING
THE WEST AND INTERIOR SECTIONS OF PUERTO RICO IN THE AFTERNOON.

&&

.AVIATION...VFR CONDS AT MOST TAF SITES WITH ISOLD-SCT SHRA/TSRA
AFTN CONVECTION ACROSS PARTS OF PR WITH BRIEF MVFR CIG/VSBY TIL AT
LEAST 07/22Z. SOME MTN TOP OBSCR IN SLOWLY MOV CONVECTION WHICH WILL
DEVELOP OVER THE CENTRAL MOUNTAIN RANGE OF PR AND STEER TOWARDS THE
NORTH AND NORTHWEST SECTIONS OF THE ISLAND. ISOLD PASSING SHRA VCTY
TIST...TISX...TNCM AND TKPK AND OVER COASTAL WATERS EN ROUTE BTW PR
AND NRN LEEWARDS. OVERALL LGT SLY WIND BLO FL200 OF 10 KTS OR LESS
AND VEERING W/HT.

&&

.MARINE...SEAS WILL GRADUALLY BUILD TONIGHT AND EARLY SUNDAY AS
PULSES OF NORTHEAST SWELLS REACH THE LOCAL ATLANTIC WATERS AND
CARIBBEAN PASSAGE. THE NORTHEAST SWELLS WILL RANGE BETWEEN 3 TO
4 FEET WITH 11 TO 13 SECONDS. PREVALING WINDS WILL BE MAINLY
SOUTHEAST AT AROUND 10 KNOTS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 89 78 88 / 20 30 30 30
STT 78 89 78 88 / 40 40 40 40

[Gustywind]

Impressive temperatures in Martinica today especially this afternoon. Meteo-France Martinica reported 35.1° Celsius at the Airport of Le Lamentin. Looks like it's a new... very hot record!

[Gustywind]

Guadeloupe is now under an orange alert for a risk of strong showers and tstorms 530 PM. I will keep your informed if i've more on that. Looks like the weak trades and the moist air produce fairly strong tstorms but at this time 'hopefully' localized in some areas of the island.