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Tropical Discussion
 
(Latest Discussion - Issued 1830Z Sep 16, 2014)
 
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Abbreviations and acronyms used in this product


TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 PM EDT TUE SEP 16 2014

AT 15 UTC TS ODILE CENTERED NEAR 28.4N 113.2W...WITH MAXIMUM
SUSTAINED WINDS OF 50KT AND CENTRAL PRESSURE OF 994 HPA...MOVING
TO THE NORTHWEST AT 8KT.

AT 15 UTC TS POLO CENTERED NEAR 12.8N 99.4W...WITH MAXIMUM
SUSTAINED WINDS OF 35KT AND CENTRAL PRESSURE OF 1005 HPA...MOVING
TO THE NORTHWEST AT 10KT.

DISCUSSION FROM SEPTEMBER 16/00UTC: AT 250 HPA...A RIDGE EXTENDS
NORTH ACROSS MEXICO TO THE WESTERN USA...WHILE CENTERING ON A
CLOSED HIGH OVER NORTHWEST MEXICO. THE RIDGE IS FORECAST TO HOLD
NEARLY UNCHANGED DURING THE NEXT FEW DAYS. THIS RIDGE IS TO
PROVIDE THE VENTILATION ALOFT AND STEERING FLOW TO TROPICAL STORMS
ODILE AND POLO. TS ODILE IS TO MOVE TO THE NORTHERN SEA OF CORTEZ
EARLY ON WEDNESDAY MORNING...WEAKENING TO A DEPRESSION AS IT
ENTERS SONORA LATER IN THE DAY. ACROSS NORTHERN BAJA
PENINSULA-SONORA THIS IS TO FAVOR ORGANIZED CONVECTION WITH
RAINFALL AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-150MM THROUGH
WEDNESDAY MORNING...WHILE ON WEDNESDAY TO THURSDAY IT IS TO
SUSTAIN RAINFALL AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-100MM.

THE NHC THEN FORECASTS TS POLO TO STRENGTHEN TO A HURRICANE EARLY
ON THURSDAY AS IT MOVES CLOSER TO THE SOUTHWEST COAST OF MEXICO.
AS IT NEARS THE COAST...THIS IS TO ENHANCE MOISTURE
TRANSPORT/CONVERGENCE. BETWEEN  GUERRERO-NAYARIT/COLIMA THIS IS TO
FAVOR RAINFALL AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-150MM.
THROUGH FRIDAY...CONVECTION IS TO BUILD NORTHWARD ACROSS SINALOA.

ALSO AT UPPER LEVELS...A TUTT NOW CENTERS OVER CENTRAL MEXICO.
UNDER INFLUENCE OF THE RIDGE TO THE NORTH THIS IS TO MIGRATE TO
THE SOUTHWEST INTO THE EASTERN TROPICAL PACIFIC EARLY IN THE
CYCLE...WHERE IT IS TO THEN RAPIDLY WEAKEN. MEANWHILE...THIS IS TO
INTERACT WITH THE ITCZ AS THE LATTER MEANDERS NORTH OF ITS
CLIMATOLOGICAL POSITION. ACROSS CENTRAL MEXICO THIS IS TO FAVOR
RAINFALL AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-125MM. ON THE
SOUTHERN STATES OF MEXICO TO GUATEMALA-EL SALVADOR/HONDURAS THE
ITCZ IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-40MM. THROUGH FRIDAY MORNING THIS IS TO DECREASE TO 05-10MM/DAY
AND MAXIMA OF 15-20MM.

PERSISTENT RIDGE PATTERN OVER THE WESTERN USA/MEXICO WILL SUSTAIN
THE GRADUAL AMPLIFICATION OF A POLAR TROUGH ACROSS THE EASTERN
USA/WESTERN ATLANTIC. THE TROUGH IS TO REACH MAXIMUM AMPLITUDE
THROUGH THURSDAY EVENING. ALTHOUGH ASSOCIATED FRONT IS TO CONFINE
TO THE SOUTHEAST USA...THE DEEP POLAR TROUGH PATTERN TO THE NORTH
IS TO INDUCE A PREFRONTAL TROUGH ACROSS THE NORTHWEST BAHAMAS
EARLY ON THURSDAY MORNING. THIS IS TO ENHANCE MOISTURE CONVERGENCE
WHILE FAVORING DEEP LAYER CONVECTIVE INSTABILITY. AS A
RESULT...EXPECTING SCATTERED CONVECTION WITH ACCUMULATION OF
10-15MM/DAY AND MAXIMA OF 20-35MM. A SLIGHT INCREASE IS EXPECTED
THROUGH THURSDAY EVENING AS UPPER TROUGH DEEPENS.

DEEPENING POLAR TROUGH TO THE WEST IS TO INTERACT WITH A TUTT OVER
THE WESTERN ATLANTIC/NORTH OF THE ISLANDS. EARLY THIS MORNING THE
TUTT CENTERED ON A LOW NORTH OF THE TURKS AND CAICOS...WITH BROAD
TROUGH ENVELOPING THE NORTHERN CARIBBEAN. AS THE POLAR TROUGH
DEEPENS TO THE WEST...THE TUTT IS FORECAST TO SHEAR/SPLIT IN TWO
VORTICES. THE NORTHERNMOST PULLS ACROSS PUERTO RICO LATER ON
WEDNESDAY...NEARING 62W/63W LATER ON THURSDAY. AS IT PULLS ACROSS
HISPANIOLA TO PUERTO RICO THIS IS TO INTERACT WITH DIURNAL
HEATING/SEA BREEZE CONVERGENCE TO RESULT IN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM. THE SOUTHERNMOST
SEGMENT...MEANWHILE...MEANDERS ACROSS THE CAYMAN ISLES/JAMAICA TO
THE EAST COAST OF NICARAGUA...WHERE IT IS TO REMAIN THROUGH
THURSDAY AFTERNOON. BUT AS IT CUTS OFF FROM THE FLOW IT IS
FORECAST TO GRADUALLY WEAKEN AS THE CYCLE PROGRESSES. THIS IS
INTERACTING WITH THE EASTERN PACIFIC ITCZ...SUSTAINING A SURGE IN
CONVECTION ACROSS NICARAGUA TO COSTA RICA/PANAMA...WHERE WE EXPECT
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM.

THE SUBEQUATORIAL RIDGE TO THE SOUTH EXTENDS EAST-TO-WEST ACROSS
NORTHERN SOUTH AMERICA...WHILE ANCHORING ON A CLOSED HIGH NEAR
ISLA DE MARGARITA. THROUGH WEDNESDAY MORNING THE HIGH WILL
RELOCATE TOWARDS LA GUAJIRA PENINSULA IN NORTHERN COLOMBIA...BUT
RIDGE PATTERN IS TO HOLD OVER THE SOUTHERN CARIBBEAN/NORTHERN
SOUTH AMERICA. THE GUIANAS WILL FALL ON THE CONVERGENT SIDE OF
THIS RIDGE...WHICH WILL LIMIT CONVECTIVE DEVELOPMENT TO COASTAL
AREAS...WHERE WE EXPECT ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF
10MM. ACROSS CENTRAL VENEZUELA EXPECTING ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-20MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
31W     33W    36W    39W    42W    45W    48W    50W     TW
52W     55W    58W    60W    63W    65W    68W    71W     TW
96W     97W    98W    DISP                              TUTT INDCD.

TROPICAL WAVE ALONG 31W IS TO CONFINE TO THE ATLANTIC ITCZ OVER
THE NEXT FEW DAYS.

TROPICAL WAVE ALONG 52W REACHES THE LESSER ANTILLES LATER ON
WEDNESDAY... WHERE IT IS TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM. THROUGH MID MORNING ON THURSDAY
IT PULLS ACROSS THE VIRGIN ISLES TO PUERTO RICO. THIS IS TO THEN
FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM.
FOLLOWING WAVE PASSAGE...A LONG FETCH SOUTHEASTERLY FLOW IS TO
ESTABLISH...WITH ITCZ MOISTURE LIFTING ACROSS THE FRENCH ISLES TO
PUERTO RICO AND THE VIRGIN ISLES...TO SUSTAIN ADDITIONAL
CONVECTION ACROSS THE LEEWARD/FRENCH ISLES WITH RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-35MM. SIMILAR AMOUNTS ARE THEN
EXPECTED ACROSS THE DOMINICAN REPUBLIC ON FRIDAY TO SATURDAY.

TUTT OVER CENTRAL MEXICO SUSTAINS AN INDUCED PERTURBATION IN THE
LOW LEVEL EASTERLIES. THIS TENDS TO WEAKEN AS IT MOVES WEST.
MEANWHILE...EXPECTING SCATTERED CONVECTION TO DEVELOP AS THIS
INTERACTS WITH THE EASTERN PACIFIC ITCZ...TO RESULT IN RAINFALL
AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-125MM.

VALVERDE...IMN (COSTA RICA)
MEDINA...ONAMET (REPUBLICA DOMINICANA)
DAVISON...WPC (USA)