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FXCA20 KWBC 131238
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
838 AM EDT THU JUL 13 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JUL
12/12UTC: THE TROPICAL WAVE THAT AFFECTED PR/USVI YESTERDAY IS NOW
OVER HISPANIOLA...AND SAHARAN DUST AND DRIER AIR IS NOW MAKING ITS
WAY TO THE LOCAL ISLANDS. THEREFORE...A DRYING TREND IS EXPECTED
TODAY...WHICH WILL CONTINUE THROUGH THE WEEKEND. THERE IS A
TROPICAL WAVE THAT WILL MOVE INTO THE SOUTHERN CARIBBEAN LATE
SATURDAY INTO SUNDAY...WELL TO THE SOUTH OF THE LOCAL
ISLANDS...WHILE PR/USVI REMAINS WITH BELOW NORMAL MOISTURE. THE
AVAILABLE MOISTURE WILL INCREASE ON MONDAY AS ANOTHER TROPICAL
WAVE...CURRENTLY ALONG 30W APPROACHES THE LOCAL ISLANDS. THE
DRYING TREND STARTING TODAY WILL BE ACCOMPANIED BY A STRONG TRADE
WIND INVERSION THROUGH FRIDAY AT AROUND 850HPA...WHICH WILL HELP
LIMIT CONVECTION OVER PR. THE INVERSION WILL BE WEAKER ON SATURDAY
AND SUNDAY...BUT MOISTURE IS FORECAST TO BE MUCH BELOW NORMAL ON
SUNDAY. THE CHANCES OF RAIN INCREASE ON MONDAY INTO TUESDAY WITH
THE APPROACHING TROPICAL WAVE. DURING THE 5-DAY PERIOD...MONDAY IS
EXPECTED TO BE THE RAINIEST DAY...FRIDAY IS EXPECTED TO BE THE
DRIEST DAY.
A SFC HIGH PRESSURE ACROSS THE WESTERN ATLANTIC WILL KEEP E-ESE
WINDS DURING THE NEXT SEVERAL DAYS. A WEAK MID LEVEL HIGH PRESSURE
IS STILL FORECAST TO MEANDER ACROSS THE ATLANTIC FOR THE NEXT
SEVERAL DAYS. IN THE UPPER LEVELS...A LOW PRESSURE IN THE WESTERN
CARIBBEAN WILL CONTINUE MOVING WEST...CAUSING SOUTHERLY WINDS IN
THE UPPER LEVELS ACROSS PR/USVI. A SHORTWAVE UPPER-LEVEL TROUGH
COULD MOVE THROUGH THE LOCAL ISLANDS THIS WEEKEND...BUT PR/USVI
WILL BE IN THE SUBSIDENT SIDE OF THE TROUGH...ESPECIALLY ON
SUNDAY. HOWEVER...ON MONDAY...THE MODEL GUIDANCE SUGGESTS THAT
THERE MAY BE SOME DIVERGENCE ALOFT...COINCIDING WITH THE
APPROACHING TROPICAL WAVE.
FOR TODAY...THE PRECIPITABLE WATER VALUES ARE EXPECTED TO DECREASE
SIGNIFICANTLY...AS SAHARAN DUST MOVES IN. THE PRECIPITABLE WATER
IS EXPECTED TO DECREASE FROM OVER 2 INCHES LAST NIGHT TO AROUND
1.6 INCHES THIS EVENING. PRECIPITABLE WATER WILL BE NEAR NORMAL
FOR THE NEXT FEW DAYS...RANGING BETWEEN 1.6 AND 1.9 INCHES THROUGH
SATURDAY. PRECIPITABLE WATER IS FORECAST TO DECREASE TO AROUND 1.3
INCHES BY SUNDAY AFTERNOON...WHICH IS ROUGHLY 2 STANDARD
DEVIATIONS BELOW NORMAL...BUT MOISTURE AND PRECIPITABLE WATER WILL
INCREASE AGAIN ON MONDAY WITH THE EXPECTED TROPICAL WAVE.
THE 5-DAY RAINFALL TOTALS ARE FORECAST TO BE AT AROUND 1.50 TO
JUST OVER 1.75 INCHES ACROSS EASTERN AND NORTHEASTERN PR...NEAR
0.5 INCHES ACROSS CENTRAL PR...AND AROUND 1 INCH ACROSS WESTERN
PR. FOR THE USVI...BETWEEN 0.25 AND 0.50 INCHES ARE FORECAST.
ALAMO/GALVEZ...WPC (USA)
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