Post by cycloneye on Apr 23, 2015 4:09:29 GMT -6
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
545 AM AST THU APR 23 2015
.SYNOPSIS...AT UPPER LEVELS...A WEAK TROUGH WILL CROSS THROUGH
THE AREA FROM THE NORTHWEST FOLLOWED BY ANTICYCLONIC NORTHWESTERLY
FLOW THROUGH THE END OF NEXT WEEK. THE FLOW REACHES UP TO 50 KNOTS
ON FRIDAY AFTERNOON THIS WEEK...BUT WEAKENS AS A STRONG HIGH
PRESSURE CENTER APPROACHES FROM THE SOUTHWEST NEXT WEEK.
AT MID LEVELS...HIGH PRESSURE OVER THE CARIBBEAN IS CENTERED OVER
THE YUCATAN PENINSULA. IT WILL SLOWLY DRIFT OVER THE LOCAL AREA
DURING THE WEEK NEXT WEEK. A WEAK TROUGH WILL MOVE THROUGH THE
AREA OVER THE WEEKEND. MID LEVELS REMAIN DRY EXCEPT FOR BRIEF
INTRUSIONS OF LOWER LEVEL MOISTURE DUE TO MOSTLY ISOLATED
CONVECTION FRIDAY THROUGH MONDAY.
AT LOWER LEVELS...THE AXIS OF HIGH PRESSURE IN THE EAST CENTRAL
ATLANTIC STRETCHES THROUGH THE SUBTROPICS TO FLORIDA. THE AXIS OF
THE RIDGE SLOWLY SINKS SOUTH OVER THE LOCAL AREA ON MONDAY AND
REMAINS OVER OR JUST NORTH OF THE AREA THROUGH THE END OF THE WEEK
GENERATING SOUTHERLY LOW LEVEL FLOW. LOWER LEVELS BECOME VERY DRY
EARLY NEXT WEEK EXCEPT FOR SOME LIMITED CONVECTION.
&&
.DISCUSSION...A FEW SHOWERS MOVED ACROSS THE CARIBBEAN WATERS WEST
OF SAINT CROIX AND AROUND VIEQUES. SOME VERY LIGHT RAIN...POSSIBLY
MEASURABLE...FELL OVER THE EASTERN FLANKS OF PUERTO RICO BUT MOST
AREAS WERE DRY. AN AREA OF MOISTURE IS VISIBLE IN SATELLITE INFRA
RED IMAGERY IN THOSE SAME AREAS AND EAST OF THE FORECAST AREA...ALTHOUGH
SUSPECT THAT MOST OF THIS IS MID LEVEL CLOUDS. SOME INCREASE IN
SHOWER ACTIVITY IS EXPECTED IN NORTHWEST PUERTO RICO THIS
AFTERNOON AND FRIDAY AND SATURDAY...BUT CONDITIONS ARE NOT
FAVORABLE FOR ANY WIDESPREAD HEAVY RAIN.
HIGH PRESSURE IS EXPECTED TO BUILD OVER THE AREA NEXT WEEK. MID
LEVELS REMAIN DRY AND LOWER LEVELS BECOME MUCH DRIER FROM TUESDAY
OF NEXT WEEK THROUGH THE FOLLOWING WEEKEND. THIS WILL GREATLY
LIMIT THE AMOUNT AND COVERAGE OF SHOWERS AND SOME DAYS LATE NEXT
WEEK MAY BE COMPLETELY DRY SHOULD CURRENT MODEL SOLUTIONS HOLD.
THIS ANALYSIS REPRESENTS VERY LITTLE CHANGE IN POPS FROM THE
PREVIOUS FORECAST AND TEMPERATURES NEXT WEEK IN THE MODEL OUTPUT
STATISTICS CONTINUE TO REMAIN AT OR NEAR RECORD LEVELS FOR THE
NORTH COAST OF PUERTO RICO. THE REMAINDER OF THE AREAS WILL BE
WARMER THAN NORMAL BUT ARE NOT EXPECTED TO BREAK ANY RECORDS.
&&
.AVIATION...
MAINLY VFR CONDITIONS EXPECTED ACROSS ALL TAF SITES FOR
THE NEXT 24 HOURS. FEW SHRA ACROSS THE LEEWARD ISLANDS FLYING AREA
DURING THE EARLY MORNING HOURS. BRIEF MVFR CONDS POSSIBLE AT TJBQ
AFTER 23/17Z DUE TO LOCALLY INDUCED AFTN CONVECTION. EAST TO
SOUTHEAST WINDS AT 5-10 KT...AFT 23/12Z BCMG SE TO S AROUND 12 KT
WITH HIGHER SEA BREEZE VARIATIONS.
&&
.MARINE...A LONG PERIOD SWELL WILL PEAK THIS EVENING AT BUOY
41043 AND MOVE INTO THE LOCAL WATERS OVERNIGHT...INCREASING SEAS
TO 6 FEET IN THE OUTER WATERS AND 5 FEET IN THE INNER WATERS. IT
IS EXPECTED THAT BREAKING WAVES WILL REMAIN UNDER 10 FEET FOR THIS
DISTANT SWELL.
&&
.FIRE WEATHER...DUE TO INCREASING MOISTURE TODAY RED FLAG
CONDITIONS ARE NOT EXPECTED. HOWEVER...EXCEPT FOR ISOLATED
SHOWERS FRIDAY THROUGH MONDAY...CONDITIONS WILL CONTINUE TO DRY
WITH ABOVE NORMAL TEMPERATURES. LATER NEXT WEEK RELATIVE
HUMIDITIES ARE EXPECTED TO BECOME UNUSUALLY LOW AND TEMPERATURES
ON THE NORTH COAST OF PUERTO RICO WILL BE MUCH ABOVE NORMAL. THIS
COULD REPRESENT THE MOST SIGNIFICANT INCREASE IN FIRE DANGER
ISLAND-WIDE THAT HAS BEEN SEEN IN THE LAST 5 YEARS. DRY CONDITIONS
WILL ALSO EXTEND TO THE U.S. VIRGIN ISLANDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 88 78 / 20 10 40 20
STT 86 77 84 77 / 10 10 20 20
NATIONAL WEATHER SERVICE SAN JUAN PR
545 AM AST THU APR 23 2015
.SYNOPSIS...AT UPPER LEVELS...A WEAK TROUGH WILL CROSS THROUGH
THE AREA FROM THE NORTHWEST FOLLOWED BY ANTICYCLONIC NORTHWESTERLY
FLOW THROUGH THE END OF NEXT WEEK. THE FLOW REACHES UP TO 50 KNOTS
ON FRIDAY AFTERNOON THIS WEEK...BUT WEAKENS AS A STRONG HIGH
PRESSURE CENTER APPROACHES FROM THE SOUTHWEST NEXT WEEK.
AT MID LEVELS...HIGH PRESSURE OVER THE CARIBBEAN IS CENTERED OVER
THE YUCATAN PENINSULA. IT WILL SLOWLY DRIFT OVER THE LOCAL AREA
DURING THE WEEK NEXT WEEK. A WEAK TROUGH WILL MOVE THROUGH THE
AREA OVER THE WEEKEND. MID LEVELS REMAIN DRY EXCEPT FOR BRIEF
INTRUSIONS OF LOWER LEVEL MOISTURE DUE TO MOSTLY ISOLATED
CONVECTION FRIDAY THROUGH MONDAY.
AT LOWER LEVELS...THE AXIS OF HIGH PRESSURE IN THE EAST CENTRAL
ATLANTIC STRETCHES THROUGH THE SUBTROPICS TO FLORIDA. THE AXIS OF
THE RIDGE SLOWLY SINKS SOUTH OVER THE LOCAL AREA ON MONDAY AND
REMAINS OVER OR JUST NORTH OF THE AREA THROUGH THE END OF THE WEEK
GENERATING SOUTHERLY LOW LEVEL FLOW. LOWER LEVELS BECOME VERY DRY
EARLY NEXT WEEK EXCEPT FOR SOME LIMITED CONVECTION.
&&
.DISCUSSION...A FEW SHOWERS MOVED ACROSS THE CARIBBEAN WATERS WEST
OF SAINT CROIX AND AROUND VIEQUES. SOME VERY LIGHT RAIN...POSSIBLY
MEASURABLE...FELL OVER THE EASTERN FLANKS OF PUERTO RICO BUT MOST
AREAS WERE DRY. AN AREA OF MOISTURE IS VISIBLE IN SATELLITE INFRA
RED IMAGERY IN THOSE SAME AREAS AND EAST OF THE FORECAST AREA...ALTHOUGH
SUSPECT THAT MOST OF THIS IS MID LEVEL CLOUDS. SOME INCREASE IN
SHOWER ACTIVITY IS EXPECTED IN NORTHWEST PUERTO RICO THIS
AFTERNOON AND FRIDAY AND SATURDAY...BUT CONDITIONS ARE NOT
FAVORABLE FOR ANY WIDESPREAD HEAVY RAIN.
HIGH PRESSURE IS EXPECTED TO BUILD OVER THE AREA NEXT WEEK. MID
LEVELS REMAIN DRY AND LOWER LEVELS BECOME MUCH DRIER FROM TUESDAY
OF NEXT WEEK THROUGH THE FOLLOWING WEEKEND. THIS WILL GREATLY
LIMIT THE AMOUNT AND COVERAGE OF SHOWERS AND SOME DAYS LATE NEXT
WEEK MAY BE COMPLETELY DRY SHOULD CURRENT MODEL SOLUTIONS HOLD.
THIS ANALYSIS REPRESENTS VERY LITTLE CHANGE IN POPS FROM THE
PREVIOUS FORECAST AND TEMPERATURES NEXT WEEK IN THE MODEL OUTPUT
STATISTICS CONTINUE TO REMAIN AT OR NEAR RECORD LEVELS FOR THE
NORTH COAST OF PUERTO RICO. THE REMAINDER OF THE AREAS WILL BE
WARMER THAN NORMAL BUT ARE NOT EXPECTED TO BREAK ANY RECORDS.
&&
.AVIATION...
MAINLY VFR CONDITIONS EXPECTED ACROSS ALL TAF SITES FOR
THE NEXT 24 HOURS. FEW SHRA ACROSS THE LEEWARD ISLANDS FLYING AREA
DURING THE EARLY MORNING HOURS. BRIEF MVFR CONDS POSSIBLE AT TJBQ
AFTER 23/17Z DUE TO LOCALLY INDUCED AFTN CONVECTION. EAST TO
SOUTHEAST WINDS AT 5-10 KT...AFT 23/12Z BCMG SE TO S AROUND 12 KT
WITH HIGHER SEA BREEZE VARIATIONS.
&&
.MARINE...A LONG PERIOD SWELL WILL PEAK THIS EVENING AT BUOY
41043 AND MOVE INTO THE LOCAL WATERS OVERNIGHT...INCREASING SEAS
TO 6 FEET IN THE OUTER WATERS AND 5 FEET IN THE INNER WATERS. IT
IS EXPECTED THAT BREAKING WAVES WILL REMAIN UNDER 10 FEET FOR THIS
DISTANT SWELL.
&&
.FIRE WEATHER...DUE TO INCREASING MOISTURE TODAY RED FLAG
CONDITIONS ARE NOT EXPECTED. HOWEVER...EXCEPT FOR ISOLATED
SHOWERS FRIDAY THROUGH MONDAY...CONDITIONS WILL CONTINUE TO DRY
WITH ABOVE NORMAL TEMPERATURES. LATER NEXT WEEK RELATIVE
HUMIDITIES ARE EXPECTED TO BECOME UNUSUALLY LOW AND TEMPERATURES
ON THE NORTH COAST OF PUERTO RICO WILL BE MUCH ABOVE NORMAL. THIS
COULD REPRESENT THE MOST SIGNIFICANT INCREASE IN FIRE DANGER
ISLAND-WIDE THAT HAS BEEN SEEN IN THE LAST 5 YEARS. DRY CONDITIONS
WILL ALSO EXTEND TO THE U.S. VIRGIN ISLANDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 88 78 / 20 10 40 20
STT 86 77 84 77 / 10 10 20 20
