Prognostic Meteorological Discussion
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
657 AM EST TUE FEB 21 2017

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM FEB 21/06
UTC: STRONG AND DEEP POLAR TROUGH IS CROSSING THE ISLANDS WHILE
CENTERING ON A LOW AT 20N 63W AND EXTENDING AN AXIS TO THE
WEST-SOUTHWEST. THE TROUGH IS MOVING TO THE SOUTHEAST. THE TROUGH
HAS A STRONG REFLECTION IN MOST OF THE TROPOSPHERE...AND AS
SUCH...IT IS LARGELY MODULATING SURFACE WINDS. THESE ARE RAPIDLY
CHANGING FROM WESTERLIES TO NORTHERLIES. THE LOW-LEVEL WINDS ARE
FORECAST TO REMAIN FROM THIS DIRECTION DURING THE REST OF TUESDAY.
THEY WILL THEN GRADUALLY VEER TO NORTH EASTERLIES DURING
WEDNESDAY...TO RETURN BACK TO EASTERLIES ON THURSDAY. THE TRADE
WIND INVERSION HAS LIFTED WITH RESPECT TO THE WEEKEND AND NOW SITS
NEAR 800 HPA...WHERE IT IS FORECAST TO REMAIN DURING MOST OF THE
WEEK. UNDER THE INFLUENCE OF BRISK NORTHERLY WINDS ON
TUESDAY...EXPECTING A SCATTERED FAST MOVING LIGHT RAIN SHOWERS
ALONG THE NORTHERN COAST OF PUERTO RICO AND THE USVI. ALL MODELS
AGREE IN THIS SOLUTION AND ALSO ON LIGHT ACCUMULATIONS. EXPECTING
MAXIMA UNDER 10MM/DAY...PEAKING IN NORTHERN SLOPES OF THE
CORDILLERA. A SIMILAR PATTERN OF ACTIVITY IS EXPECTED ON WEDNESDAY
WITH GRADUAL DECREASE IN THE FREQUENCY OF SHOWERS ALONG THE
NORTHERN COAST AND A SLIGHT INCREASE IN AFTERNOON CONVECTION ALONG
THE CORDILLERA AND ITS SOUTHERN FLANKS. AFTER THURSDAY WINDS TRADE
WINDS ARE TO BECOME FROM THE SOUTHEAST THROUGH THE WEEKEND AS
ANOTHER POLAR TROUGH APPROACHES. THIS WILL SET UP A DRIER AND
WARMER PATTERN ONCE AGAIN.

JIMENEZ...IMN (COSTA RICA)
SUBRATH-ALI...TTMS (TRINIDAD AND TOBAGO)
GALVEZ...WPC (USA)

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