559
FXCA62 TJSJ 161825
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
225 PM AST WED OCT 16 2013
.SYNOPSIS...UPPER LONG WAVE TROUGH WILL CONTINUE TO AMPLIFY AND DIG
FURTHER SOUTH ACROSS THE REGION THROUGH THE END OF THE WORK WEEK...
A TUTT LOW IS EXPECTED TO FORM JUST NORTH OF THE AREA BY SATURDAY
THEN LINGER THROUGH THE EARLY PART OF NEXT WEEK. THIS WILL
KEEP THE LOCAL AREA IN A FAIRLY UNSTABLE UPPER LEVEL ENVIRONMENT...
AND FAVORABLE FOR ENHANCEMENT OF CONVECTIVE ACTIVITY FOR THE NEXT
SEVERAL DAYS. HIGH PRESSURE RIDGE NORTHEAST OF THE REGION WILL
CONTINUE TO RETREAT FURTHER NORTHEAST AS A SURFACE TROUGH WEST OF
THE AREA BECOMES AMPLIFIED AND SPREADS NORTHWARD INTO THE WESTERN
ATLANTIC. THIS WILL RESULT IN A WEAK PRESSURE GRADIENT AND FAIRLY
LIGHT EAST TO SOUTHEAST WIND THROUGH AT LEAST FRIDAY. THEREAFTER
WINDS ARE TO BECOME MORE EASTERLY OVER THE WEEKEND AS HIGH PRESSURE
REESTABLISHES ITSELF NORTH OF THE AREA ONCE AGAIN.
ANOTHER LOW LEVEL TROUGH/EASTERLY WAVE LIES JUST EAST OF THE LESSER
ANTILLES. THIS FEATURE WILL SLOWLY WEAKEN AS IT CONTINUES WESTWARD
AND ENTERS THE EASTERN CARIBBEAN OVER THE NEXT 24 HOURS. AT THE MOMENT...
NOT MUCH MOISTURE/CONVECTION WITH THIS FEATURE AS MUCH OF IT WAS BEING
SHEARED BY A TUTT ALOFT.
&&
.DISCUSSION...LATEST SATELLITE IMAGERY AND DOPPLER WEATHER RADAR AS
WELL AS MODEL GUIDANCE ALL SUGGEST SLOT OF DRY AIR NOW OVER THE
REGION AND THUS LIMITING THE CONVECTIVE DEVELOPMENT. THE PROXIMITY
OF THE UPPER LEVEL TROUGH HOWEVER WILL STILL KEEP CONDITIONS
FAVORABLE FOR ENHANCEMENT OF AFTERNOON CONVECTION WHEN SHOWERS DO
FORM ESPECIALLY OVER THE PARTS OF THE INTERIOR AND WEST SECTIONS
OF PUERTO RICO THIS AFTERNOON.
A QUICK SURGE OF ADDITIONAL LOW TO MID LEVEL MOISTURE IS HOWEVER EXPECTED
TO ARRIVE BY THURSDAY AFTERNOON ACCOMPANYING THE AFOREMENTIONED WEAKENING
SURFACE TROUGH EAST OF THE AREA. THIS WILL AGAIN INCREASE THE CHANCES
FOR SHOWER DEVELOPMENT AND CONVECTIVE ENHANCEMENT ACROSS THE ISLANDS
AND SURROUNDING WATERS THROUGH AT LEAST FRIDAY. THE AMPLIFYING UPPER
TROUGH ALONG WITH LIGHT SURFACE WINDS AND AMPLE MOISTURE WILL PROVIDE
FAVORABLE CONDITIONS FOR POSSIBLE DEVELOPMENT OF STRONG AFTERNOON
THUNDERSTORMS IN ISOLATED AREAS ACROSS PARTS OF PUERTO RICO ON THURSDAY
AND POSSIBLY ON FRIDAY. THE LIMITATION HOWEVER IS HOW MUCH MOISTURE
WILL BE ADVECTED ACROSS THE REGION ACCOMPANYING THIS LOW LEVEL TROUGHINESS
WHICH AT THE MOMENT DOES NOT SHOW OR SUGGEST SIGNIFICANT AMOUNTS
OF LOW LEVEL MOISTURE ADVECTION.
&&
.AVIATION...VFR CONDS ACROSS ALL SITES. EXCEPT ACROSS TJMZ AND TJBQ
DUE TO POSSIBLE SHRA/ISOLD TSRA UNTIL 16/21Z. MOUNTAIN OBSCURATIONS
ALSO POSSIBLE DURG THAT TIME. LIGHT SOUTHEAST TO EAST WINDS AT LESS
THAN 10 KT ARE EXPECTED BLO FL020 BCMG EASTERLY AT 10-15 KTS UP TO
FL150. NO OPERATIONAL WEATHER IMPACTS OR FLYING HAZARDS ANTICIPATED
AT THE MOMENT.
&&
.MARINE...SEAS UP TO 4 FEET AND WINDS UP TO 16 KNOTS ARE EXPECTED
OVER THE COASTAL WATERS OVERNIGHT. FAIRLY TRANQUIL SEAS FOR THE
NEXT FEW DAYS...EXCEPT FOR SOME ISOLATED THUNDERSTORMS ACROSS PARTS
OF THE COASTAL WATERS EACH DAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 77 88 76 89 / 30 50 20 40
STT 77 88 78 87 / 40 40 40 40
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...NONE.
&&
$$
02/09