Prognostic Meteorological Discussion
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FXCA20 KWBC 171113
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
612 AM EST TUE JAN 17 2017

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN 17/06
UTC: AT UPPER LEVELS...A LONG WAVE RIDGE EXTENDS NORTH ALONG 90W
FROM THE EASTERN TROPICAL PACIFIC TO THE CENTRAL USA. THE RIDGE IS
TO SLOWLY MEANDER ACROSS THE EASTERN USA EARLY ON WEDNESDAY
MORNING. AS IT RELOCATES...THE RIDGE WILL DISPLACE A TROUGH ACROSS
THE FORECAST AREA...WITH AXIS TO MOVE ACROSS THE LESSER ANTILLES
BY MIDDAY ON WEDNESDAY. ON ITS WAKE...A STRONG UPPER CONVERGENT
PATTERN IS TO ESTABLISH... WITH CAP INVERSION TO DROP TO 800/850
HPA LATER IN THE DAY/EARLY ON THURSDAY MORNING. THIS PATTERN WILL
THEN HOLD THROUGH THE END OF THE WEEK.

AT LOW LEVELS...BROAD RIDGE DOMINATES THE FLOW ACROSS THE WESTERN
ATLANTIC. AXIS...HOWEVER...IS EXPECTED TO GRADUALLY WEAKEN WHILE
MEANDERING EAST TOWARDS THE CENTRAL ATLANTIC. EARLY IN THE CYCLE
THIS IS TO FAVOR BRISK EAST-NORTHEAST WINDS THAT ARE TO PEAK AT
15-20KT. THROUGH WEDNESDAY AFTERNOON WINDS WILL DECREASE TO
05-10KT...A PATTERN THAT IS TO HOLD THROUGH FRIDAY MORNING. WINDS
WILL THEN BACK TO THE NORTH-NORTHWEST AS ANOTHER RIDGE ROLLS
ACROSS THE EASTERN USA TO THE WESTERN ATLANTIC DURING THE
WEEKEND...WITH BOUNDARY LAYER WINDS TO REMAIN BETWEEN 05-10KT. AS
THE LIGHTER TRADES SET IN...DIURNAL/DIURNAL PATTERN WILL THEN
DOMINATE.

IN THIS PATTERN...THE MOST ACTIVE CONVECTION IS EXPECTED DURING
THE DAY TODAY...WITH NORTHEASTERLY TRADES TO ENHANCE MOISTURE
CONVERGENCE ACROSS WESTERN INTERIOR/SOUTHWEST PORTIONS OF PUERTO
RICO...WHILE ALSO FAVORING PASSING SHOWERS ACROSS NORTHEAST
PORTIONS OF THE ISLAND AND THE NORTHERN VI. STRONG CAP INVERSION
AND LIGHTER TRADES WILL THEN FAVOR MOSTLY FAIR WEATHER CONDITIONS
FOR THE REST OF THE WORKWEEK. EARLY MORNING SHOWERS WILL LIMIT TO
EASTERN PUERTO RICO AS THE EASTERLY TRADES CONVERGE WITH THE
OUTFLOWING LAND BREEZE...WHILE AFTERNOON SHOWERS ARE TO GENERALLY
CONFINE TO THE CORDILLERA. BUT FOR THE MOST PART ONLY EXPECTING
LIGHT RAINFALL AMOUNTS.

TROPICAL DISCUSSION FROM JAN 17/12 UTC:

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:

INITIAL   24     36     48     60     72     84     96    TYPE
NONE

JIMENEZ...IMN (COSTA RICA)
MIRANDA...INAMEH (VENEZUELA)
DAVISON...WPC (USA)

$$




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