Prognostic Meteorological Discussion
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FXCA20 KWBC 291823
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
222 PM EDT TUE JUL 29 2014

DISCUSSION FROM JULY 29/00UTC: THE MID/UPPER LEVEL RIDGE
DOMINATING THE WESTERN USA/NORTHERN MEXICO IS FORECAST TO PERSIST
OVER THE NEXT FEW DAYS. THE RIDGE IS FORECAST TO ANCHOR AT 250 HPA
ON A CLOSED HIGH OVER NEW MEXICO/NORTHERN CHIHUAHUA.
FURTHERMORE...THE MID/UPPER LEVEL RIDGE IS TO ALSO EXTEND EAST
ACROSS THE NORTHERN GULF OF MEXICO-FLORIDA PENINSULA TO THE
BAHAMAS. BUT UNDER PRESSURE FROM AMPLIFYING TROUGH OVER THE USA
THIS IS TO GRADUALLY SPLIT IN TWO CELLS AS THE CYCLE PROGRESSES. A
TUTT LOW LIES TO THE SOUTH OF THIS RIDGE...CENTERING OFF THE
SOUTHWEST COAST OF MEXICO. UNDER INFLUENCE OF THE RIDGE...THE
LOW/TROUGH IS TO LIFT ACROSS THE BAJA PENINSULA THROUGH WEDNESDAY
EVENING-THURSDAY MORNING. EARLY THIS CYCLE THIS IS TO ENHANCE
CONVECTION ACROSS CENTRAL STATES OF MEXICO TO SUSTAIN RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. ACROSS BAJA
PENINSULA SUR IT IS TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-30MM LATER ON TUESDAY TO EARLY WEDNESDAY...WHILE
ACROSS SINALOA-SONORA IT IS TO FAVOR RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 35-70MM ON TUESDAY TO THURSDAY EVENING.

THE POLAR TROUGH OVER NORTH AMERICA EXTENDS SOUTH BETWEEN 90W-70W
TO 20N. THIS IS TO REACH MAXIMUM AMPLITUDE EARLY IN THE FORECAST
CYCLE. THROUGH WEDNESDAY EVENING THE TROUGH WILL START TO LIFT AS
ANOTHER AMPLIFIES ACROSS THE CENTRAL USA LATER ON THURSDAY/EARLY
ON FRIDAY MORNING. AT LOW LEVELS IT SUSTAINS A DEEP TROUGH ALONG
THE EASTERN SEABOARD OF THE USA...WITH ASSOCIATED FRONT TRAILING
ACROSS THE NORTHERN GULF. THIS BOUNDARY WEAKENS THROUGH WEDNESDAY
EVENING. ACROSS THE NORTHWEST BAHAMAS...MEANWHILE...THIS IS TO
SUSTAIN A PREFRONTAL TROUGH...FORECAST TO ENHANCE MOISTURE
CONVERGENCE. THIS IS TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-25MM.

FARTHER EAST...MID/UPPER LEVEL ANALYSIS SHOWS A TUTT LOW NEAR 24N
65W. THIS LOW EXTENDS A SHORT WAVE TROUGH SOUTH TO THE NORTHEAST
CARIBBEAN...AND WEST ACROSS HISPANIOLA TO A LOW NEAR JAMAICA.
UNDER INFLUENCE OF THE RIDGE TO THE WEST...THE TUTT IS TO STRETCH
FARTHER WEST INTO THE WESTERN CARIBBEAN/ NORTHERN CENTRAL
AMERICA...WITH AXIS TO THEN GRADUALLY SPLIT IN TWO THROUGH
THURSDAY MORNING. THE NORTHERN HALF OF THIS AXIS IS TO MEANDER
NORTH OF PUERTO RICO/HISPANIOLA THROUGH EARLY THURSDAY MORNING.
BUT IT THEN STARTS TO RETROGRESS AS A RIDGE BUILDS FROM THE EAST.
THE SOUTHERN HALF...MEANWHILE... IS TO MEANDER SOUTH OF JAMAICA
AND THE CAYMAN ISLES THROUGH WEDNESDAY AFTERNOON. IT THEN WEAKENS
TO AN INVERTED TROUGH AS IT RETROGRESSES ACROSS CENTRAL AMERICA
LATER ON THURSDAY. THE TUTT ALOFT IS TO ENHANCE SEA BREEZE RELATED
CONVECTION ACROSS JAMAICA-HISPANIOLA AND PUERTO RICO. ACROSS
JAMAICA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM...WITH MOST ACTIVE EXPECTED OVER THE NEXT COUPLE OF DAYS.
ACROSS HISPANIOLA THE MOST ACTIVE IS EXPECTED ACROSS CENTRAL
PORTIONS OF THE ISLAND...WITH ACCUMULATION OF 05-10MM/DAY AND
MAXIMA OF 15MM. OVER PUERTO RICO EXPECTING SIMILAR AMOUNTS...WITH
MOST ACTIVE ON THE CORDILLERA CENTRAL AND WESTERN INTERIOR
PORTIONS OF THE ISLAND. AS THE TROUGH RETROGRESSES ACROSS CENTRAL
AMERICA IT IS TO INITIALLY FAVOR AN UPPER CONVERGENT/SUBSIDENT
PATTERN. BUT AS THE UPPER TROUGH RETROGRESSES ACROSS HONDURAS/EL
SALVADOR DIVERGENCE ALOFT WILL BRIEFLY ESTABLISH. AS A
RESULT...EXPECTING AN INCREASE IN ACTIVITY THROUGH MIDDAY ON
THURSDAY...WHEN THIS IS LIKELY TO ENHANCE DIURNAL CONVECTION TO
SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM.
OTHER CONVECTIVE ENHANCEMENT IS EXPECTED ALONG THE BASE OF THE
TROUGH ACROSS COSTA RICA/NICARAGUA...WHERE IN INTERACTION WITH THE
ITCZ IT IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-45MM. THE TROUGH ALOFT SUSTAINS A COUPLE OF INDUCED
PERTURBATION IN THE EASTERLY TRADES...PLEASE SEE BELOW FOR
DETAILS/FORECAST.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
39W     41W    44W    46W    49W    51W    54W    57W     TW
59W     61W    63W    65W    66W    67W    69W    71W     TUTT
INDUCED
68W     70W    73W    75W    76W    77W    80W    83W     TUTT
INDUCED
91W     93W    96W   100W   104W   107W   109W   112W     TW

THE TROPICAL WAVE ALONG 39W SUSTAINS AN AREA OF ORGANIZED
CONVECTION ALONG THE ATLANTIC ITCZ. THE NHC CONTINUES TO MONITOR
THIS SYSTEM FOR POSSIBLE TROPICAL CYCLONE FORMATION DURING THE
NEXT TWO DAYS.

A TUTT INDUCED PERTURBATION ON THE EASTERLY TRADES EXTENDS ALONG
59W. THIS MOVES ACROSS THE LESSER ANTILLES LATER TODAY...MEANWHILE
DRAWING ITCZ MOISTURE NORTHWARD ACROSS THE ISLAND CHAIN. A MOIST
PLUME IS TO THEN PULL ACROSS THE FRENCH/LEEWARD ISLES THROUGH
WEDNESDAY MORNING...REACHING THE USVI/PUERTO RICO LATER ON
THURSDAY. OVER THE FRENCH/LEEWARD-VIRGIN ISLES IT IS TO FAVOR
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. OVER PUERTO
RICO AND THE DOMINICAN REPUBLIC EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM IN SCATTERED CONVECTION LATER ON
WEDNESDAY TO THURSDAY. OVER EASTERN-CENTRAL VENEZUELA... IN
INTERACTION WITH THE NEAR EQUATORIAL TROUGH...IT IS TO THEN FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM...WHILE OVER
NORTHWEST VENEZUELA EXPECTING ACCUMULATION OF 05-10MM/DAY AND
MAXIMA OF 15-25MM.

ANOTHER TUTT INDUCED PERTURBATION IS INITIALIZED ALONG 68W. THIS
MOVES ACROSS EASTERN HISPANIOLA EARLY THIS CYCLE TO SUSTAIN
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. ACROSS
JAMAICA/EASTERN CUBA IT IS TO THEN FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM ON WEDNESDAY/EARLY THURSDAY
MORNING...WHILE OVER THE CAYMAN ISLES EXPECT ACCUMULATION OF
00-05MM/DAY AND MAXIMA OF 10MM.

TROPICAL WAVE ALONG 91W IS TO SUSTAIN ORGANIZED CONVECTION ACROSS
CHIAPAS IN SOUTHERN MEXICO...WITH RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-40MM. ON THE CENTRAL-SOUTHWEST STATES OF
MEXICO...IN INTERACTION WITH A TUTT TO THE WEST IT IS TO TRIGGER
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 35-70MM ON DAYS 02
AND 03.

FIGUEROA...MARN (EL SALVADOR)
VALVERDE...IMN (COSTA RICA)
DAVISON...WPC (USA)
$$




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