Prognostic Meteorological Discussion
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000
FXCA20 KWBC 291044
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
644 AM EDT THU SEP 29 2016

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM SEPTEMBER
29/06 UTC: BROAD CELL OF THE SUBTROPICAL RIDGE REMAINS DOMINANT
MID LEVEL FEATURE ACROSS THE WESTERN ATLANTIC TO THE NORTHERN
CARIBBEAN ISLES. THE RIDGE...AS IT HOLDS...WILL ANCHOR AT 500 HPA
ON A CLOSED HIGH NEAR BERMUDA. THE RIDGE IS PROVIDING THE STEERING
FLOW TO TROPICAL STORM MATTHEW...WITH NHC FORECASTING A WESTERLY
MOTION WHILE REMAINING TO THE SOUTH OF 15N. ALTHOUGH THE STORM IS
TO REMAIN FAR TO THE SOUTH...OUTER BAND CONVECTION IS TO STREAM
ACROSS SAINT CROIX AND THE CARIBBEAN COASTAL WATERS OF PUERTO RICO
DURING THE NEXT 12-18 HRS. MOST ACTIVE...HOWEVER...IS LIKELY TO
LIMIT TO SAINT CROIX...WHERE WE EXPECT DAILY MAXIMA TO PEAK AT 1-2
INCHES. IN A TIGHT GRADIENT...THE STORM IS TO ALSO FAVOR EASTERLY
TRADES OF 25-30KT THROUGH FRIDAY MORNING. BRISK EASTERLY WINDS OF
15-20KT ARE TO THEN PERSIST THROUGHOUT THE WEEKEND. THIS IS TO
FAVOR GENERATION OF STREAMERS ACROSS THE NORTHERN LEEWARD/VIRGIN
ISLES THAT ARE TO AFFECT EASTERN-NORTHEASTERN PUERTO RICO FROM
TIME TO TIME...WITH RAINFALL MAXIMA OF LESS THAN AN INCH TO
GENERALLY LIMIT TO EL YUNQUE RAINFOREST.

LATER DURING THE WEEKEND/EARLY NEXT WEEK...THE NHC FORECASTS THE
STORM TO LIFT NORTH BETWEEN HAITI AND JAMAICA. IN RESPONSE THE LOW
LEVEL WINDS WILL START TO VEER TO THE SOUTH-SOUTHEAST...ENHANCING
ITCZ MOISTURE ADVECTION ACROSS THE EASTERN CARIBBEAN INTO THE
FORECAST AREA. BOTH THE GFS AND ECMWF SHOW PWAT PEAKING AROUND TWO
INCHES AS THE MOIST ADVECTIVE PATTERN BECOMES WELL ESTABLISHED
EARLY NEXT WEEK. IF THE MID LEVEL RIDGE WEAKENS AS SOME OF THE
MODELS SUGGEST...THIS COULD RESULT IN SOME MODERATE TO HEAVY
RAINFALL AMOUNTS ACROSS THE ENTIRE FORECAST AREA.

AGRAMONTE...ONAMET (DOMINICAN REPUBLIC)
CASTILLO...UCR (COSTA RICA)
CONTRERAS...IMN (COSTA RICA)
DAVISON/GALVEZ...WPC (USA)
$$




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