Prognostic Meteorological Discussion
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FXCA20 KWBC 301828
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
227 PM EDT FRI SEP 30 2016

AT 15 UTC HURRICANE MATTHEW CENTERED NEAR 13.7N 70.8W...WITH
MAXIMUM SUSTAINED WINDS OF 100KT AND MINIMAL CENTRAL PRESSURE OF
968 HPA. THE STORM IS MOVING WEST-SOUTHWEST AT 10KT...SEE NHC
DISCUSSION FOR DETAILS AND OFFICIAL FORECAST.

TROPICAL DISCUSSION FROM SEPTEMBER 29/12UTC: AT 500 HPA THE
SUBTROPICAL RIDGE EXTENDS ACROSS MEXICO/CENTRAL USA-THE
GULF-NORTHERN CENTRAL AMERICA. THE RIDGE IS TO ANCHOR ON A CLOSED
HIGH THAT MEANDERS SOUTH OF THE BAJA PENINSULA LATER ON SATURDAY.
THE RIDGE ALOFT IS TO VENT DIURNAL CONVECTION ACROSS MEXICO. OVER
THE WESTERN STATES OF SONORA-SINALOA EXPECTING RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM. THROUGH SUNDAY IT WILL DECREASE
TO 05-10MM/DAY AND MAXIMA OF 15-25MM. ON THE SOUTHWEST-CENTRAL
STATES...MEANWHILE...EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-35MM. THROUGH SUNDAY IT WILL DECREASE TO 05-10MM/DAY
AND MAXIMA OF 15-25MM. ON THE SOUTHERN STATES OF MEXICO EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH
SUNDAY IT DECREASE TO 00-05MM/DAY AND MAXIMA OF 10MM.

DOWNSTREAM FROM THE CONTINENTAL RIDGE...A LONG WAVE TROUGH EXTENDS
SOUTH ACROSS THE EASTERN USA/EASTERN GULF TO THE NORTHWEST
CARIBBEAN/NORTHERN CENTRAL AMERICA. AT 250 HPA THE TROUGH REACHES
MAXIMUM AMPLITUDE LATER TODAY...AND THIS PATTERN IS TO HOLD DURING
THE NEXT TWO DAYS. LATER ON SUNDAY IT IS FORECAST TO RETROGRESS
ACROSS THE YUCATAN TO THE CAMPECHE SOUND/SOUTHERN STATES OF MEXICO
AS THE SUBEQUATORIAL RIDGE BUILDS TO THE EAST OVER THE CARIBBEAN.
MEANWHILE...THE LONG WAVE TROUGH WILL ENHANCE CONVECTION ACROSS
WESTERN/CENTRAL CUBA AND THE BAHAMAS...TO FAVOR RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH SUNDAY THIS WILL
DECREASE TO 00-05MM/DAY AND MAXIMA OF 10MM. ACROSS NORTHERN
HONDURAS-BELIZE AND GUATEMALA THE DEEP UPPER TROUGH IS TO VENT
CONVECTION TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-30MM/DAY. AS IT MEANDERS WEST ACROSS THE YUCATAN TO SOUTHERN
MEXICO THIS WILL DECREASE TO 05-10MM/DAY AND MAXIMA OF 15MM.

AT LOW LEVELS...THE CONTINENTAL TROUGH SUSTAINS AN ELONGATED FRONT
ACROSS THE SOUTHERN USA TO THE NORTHERN GULF OF MEXICO TO SOUTH
TEXAS/NORTHEAST MEXICO. OVER NORTHEAST MEXICO THIS WILL TRIGGER
SCATTERED CONVECTION. ON FRIDAY TO SATURDAY THE FOCUS OF THE
ACTIVITY WILL BE BETWEEN TAMAULIPAS AND VERACRUZ WHERE IT WILL
FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.
THROUGH SATURDAY THIS WILL DECREASE TO 05-10MM/DAY AND MAXIMA OF
15MM...WITH THE FRONT EXPECTED TO FRONTOLIZE ON SUNDAY.

BROAD CELL OF THE SUBEQUATORIAL RIDGE LIES OVER THE CARIBBEAN
BASIN AND INTO NORTHERN SOUTH AMERICA/SOUTHERN CENTRAL AMERICA.
THE RIDGE ALOFT IS VENTING CONVECTION IN ASSOCIATION WITH
HURRICANE MATTHEW. THE NHC FORECAST THE HURRICANE TO MEANDER OFF
THE NORTH COAST OF COLOMBIA THROUGH SUNDAY MORNING. OUTER BAND
CONVECTION ACROSS LA GUAJIRA-ABC ISLES AND FALCON IN NORTHERN
VENEZUELA WILL RESULT IN ACCUMULATION OF 50-100MM. THROUGH THE
EARLY MORNING HOURS ON MONDAY IT IS EXPECTED TO LIFT TOWARDS
EASTERN JAMAICA. AS IT NEARS JAMAICA IT WILL TRIGGER RAINFALL
AMOUNTS OF 75-125MM AND MAXIMA OF 150-250MM...WITH POTENTIAL FOR
HIGHER AMOUNTS DEPENDING ON THE TRAJECTORY. HIGHER AMOUNTS ARE
EXPECTED TO THE EAST ACROSS HISPANIOLA BETWEEN THE HAITIAN
PENINSULA AND PENINSULA DE BARAHONA...WHERE WE EXPECT ACCUMULATION
OF 125-250MM AND MAXIMA OF 350-500MM. OVER WESTERN PORTIONS OF THE
HAITIAN PENINSULA STORM TOTAL AMOUNTS ARE LIKELY TO EXCEED 500MM.


THE SUBEQUATORIAL RIDGE...AS IT MEANDERS OVER NORTHERN SOUTH
AMERICA...IS TO VENT DIURNAL CONVECTION. ACROSS COLOMBIA...THE
HURRICANE TO THE NORTH IS TO ENHANCE ONSHORE FLOW ACROSS THE
WESTERN PLAINS TO THE ANDEAN REGION...TO RESULT IN RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. BUT AS THE HURRICANE
LIFTS AWAY LATER ON SUNDAY THIS WILL DECREASE TO 05-10MM/DAY AND
MAXIMA OF 15-25MM. HIGHER AMOUNTS ARE EXPECTED BETWEEN NORTHERN
PERU-EASTERN COLOMBIA AND NORTHWEST VENEZUELA THROUGH MONDAY
MORNING...WHERE UNDER INFLUENCE OF THE TROPICAL CYCLONE EXPECTING
RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 40-80MM. OTHER
CONVECTION TO THE EAST OVER VENEZUELA AND NORTH WILL RESULT IN
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:

INITIAL  24      36      48      60      72      84      96
TYPE
49W      52W     55W    57W     59W     60W     61W     62W  TUTT
INDUCED
92W      94W     96W    98W    100W    102W     DISSIPATES
EW

BROAD TUTT OVER THE CENTRAL ATLANTIC SUSTAINS AN INDUCED/INVERTED
TROUGH IN THE EASTERLY TRADES...WITH AXIS NORTH ALONG 49W. THIS
REACHES THE ISLAND CHAIN LATE ON SUNDAY. AS IT ENTERS THE ISLANDS
THIS WILL INTERACT WITH THE ATLANTIC ITCZ TO TRIGGER LIGHT TO
MODERATE CONVECTION ACROSS THE NORTHERN WINDWARD AND FRENCH
ISLES...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM LATER ON SUNDAY.

EASTERLY WAVE ALONG 92W MOVES ACROSS THE SOUTHERN STATES OF MEXICO
LATER TODAY. MEANWHILE...IN INTERACTION WITH THE ITCZ IT IS TO
SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.
LATER ON SATURDAY TO EARLY SUNDAY MORNING IT REACHES THE
CENTRAL-SOUTHWEST STATES OF MEXICO...TRIGGERING RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-35MM. LATER ON SUNDAY IT WILL
FAVOR SCATTERED CONVECTION ACROSS THE WESTERN MEXICO WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM.

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





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