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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1820Z Jul 18, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
220 PM EDT FRI JUL 18 2014

DISCUSSION FROM JULY 18/00UTC: UPPER LEVEL RIDGE PATTERN IS TO
REMAIN WELL ENTRENCHED ACROSS MEXICO/SOUTHWEST USA DURING THE NEXT
FEW DAYS. AT 250 HPA IT IS NOW TO ANCHOR ON A CLOSED HIGH OVER
NORTHERN COAHUILA/EASTERN CHIHUAHUA. AS THE RIDGE HOLDS...A TUTT
OVER THE EASTERN PACIFIC IS TO LIFT ACROSS THE BAJA PENINSULA TO
SOUTHERN CALIFORNIA THROUGH SATURDAY EVENING. AS THE TROUGH
PRESSES AGAINST THE RIDGE...AND GRADIENT TIGHTENS...A SUBTROPICAL
JET MAXIMA IS TO DEVELOP OVER NORTHWEST MEXICO. THIS IS TO SUSTAIN
AREAS OF DIVERGENCE ALOFT WHILE LIFTING ACROSS SONORA MEXICO. THIS
WILL PROVIDE VENTILATION TO DIURNAL CONVECTION BUILDING ALONG THE
SIERRA MADRE OCCIDENTAL...TO SUSTAIN SCATTERED CONVECTION. ACROSS
SONORA INITIALLY EXPECTING ACCUMULATION OF 10-15MM/DAY AND MAXIMA
OF 20-35MM. THROUGH SATURDAY THIS IS TO INCREASE TO 15-20MM/DAY
AND MAXIMA OF 35-70MM. ACROSS SINALOA TO
COLIMA/NAYARIT...MEANWHILE...EXPECT ACCUMULATION OF 15-20MM/DAY
AND MAXIMA OF 25-50MM.

THE RIDGE ALOFT IS TO ALSO STEER A TUTT ACROSS CENTRAL
AMERICA/SOUTHERN MEXICO. EARLY IN THE PERIOD THE TUTT WILL EXTEND
FROM EL SALVADOR/HONDURAS TO SOUTHERN STATES OF MEXICO. UNDER
INFLUENCE OF THE RIDGE TO THE NORTH THIS WILL RETROGRESS INTO THE
EASTERN PACIFIC TO SOUTHERN MEXICO LATER ON SATURDAY...REACHING
SOUTHWEST MEXICO BY 72-84 HRS. EARLY IN THE CYCLE THIS IS TO
ENHANCE CONVECTIVE DEVELOPMENT ALONG THE CONTINENTAL DIVIDE OVER
EL SALVADOR/HONDURAS TO GUATEMALA...TO RESULT IN RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15-20MM.. ACROSS GUATEMALA TO
SOUTHERN-CENTRAL MEXICO THIS IS TO FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM.

FARTHER EAST...A TUTT LOW MEANDERS JUST EAST OF THE BAHAMAS. THIS
LOW/TROUGH REMAINS CUT OFF FROM THE FLOW...AND AS SUCH IT IS
EXPECTED TO GRADUALLY WEAKEN TO AN INVERTED TROUGH LATER ON
SUNDAY. BUT AS IT MEANDERS OVER THE BAHAMAS-CUBA THIS IS TO
ENHANCE CONVECTIVE INSTABILITY. AT LOW LEVELS...AN INVERTED TROUGH
IS TO EXTEND NORTH ACROSS CENTRAL CUBA-THE BAHAMAS TO THE WESTERN
ATLANTIC. THIS IS TO PERSIST DURING THE NEXT THREE
DAYS...WEAKENING LATER ON DAY 04 (MONDAY). ACROSS THE BAHAMAS AND
CUBA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-35MM. LOCALLY HIGHER AMOUNTS...HOWEVER...ARE POSSIBLE ON HIGHER
ELEVATIONS OVER CENTRAL CUBA.

BROAD MID/UPPER LEVEL TROUGH IS TO THEN ESTABLISH ACROSS THE
EASTERN USA TO THE NORTHERN GULF OF MEXICO. THIS...IN-TURN...WILL
INDUCE THE NORTHWARD AMPLIFICATION OF A RIDGE ACROSS THE WESTERN
ATLANTIC/EASTERN SEABOARD OF THE USA. RIDGE PATTERN IS TO
GRADUALLY BECOME BETTER ORGANIZED AS THE CYCLE PROGRESSES.
BUILDING RIDGE IS TO THEN FORCE A BROAD TUTT OVER THE CENTRAL
ATLANTIC TO RETROGRESS. THE TUTT IS TO CENTER ON A DEEP LOW NEAR
30N 50W...WITH AXIS SOUTHWEST TO JUST NORTH OF THE LESSER
ANTILLES. THROUGH SUNDAY AFTERNOON THE TUTT IS TO AMPLIFY TO JUST
NORTH OF THE DOMINICAN REPUBLIC. THIS IS A FAIRLY DEEP MID/UPPER
LEVEL FEATURE...AND AT LOW LEVELS IT IS TO SUSTAIN AN
INDUCED/INVERTED TROUGH IN THE EASTERLY TRADES. BEST MOISTURE
CONVERGENCE WITH THIS FEATURE...HOWEVER...IS EXPECTED FAR TO THE
NORTH AND AWAY FROM THE NORTHERN CARIBBEAN ISLANDS. SOME
CONVECTIVE ENHANCEMENT IS HOWEVER POSSIBLE ACROSS PORTIONS OF
HISPANIOLA LATER ON SATURDAY/SUNDAY...WHEN WE EXPECT RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM/DAY. AT MID LEVELS...A
SHORT WAVE RIDGE IS TO MEANDER OVER THE NORTHEAST CARIBBEAN ISLES.
THIS RIDGE IS TO SUSTAIN A TRADE WINDS CAP THAT IS TO INHIBIT
ORGANIZED DEEP CONVECTION. A BROAD CELL OF THE SUBTROPICAL
RIDGE...MEANWHILE...WILL DOMINATE FLOW ACROSS THE ATLANTIC
BASIN...ADVECTING SHALLOW MOISTURE ACROSS THE LESSER ANTILLES
WHILE ALSO TRIGGERING STREAMERS. THESE ARE TO SUSTAIN RAINFALL
AMOUNT OF 00-05MM/DAY AND WIDELY ISOLATED MAXIMA OF 10MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
45W     47W    49W    51W    54W    57W    60W    62W     TW
61W     64W    68W    71W    74W    77W    79W    82W     TW
84W     87W    90W    93W    96W    99W   101W   103W     EW

A TROPICAL WAVE IS INITIALIZED AT 45W. THIS WAVE WILL ENTER FRENCH
GUIANA ON SATURDAY MORNING...AND REACHES NORTHEAST
VENEZUELA/WINDWARD ISLES EARLY ON MONDAY MORNING. AT IS ENTERS THE
GUIANAS EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-25MM...WHILE OVER NORTHEAST VENEZUELA/ORINOCO DELTA-WINDWARD
ISLANDS IT IS TO RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM.

A TROPICAL WAVE ALONG 61W...IN INTERACTION WITH THE ITCZ...SUSTAIN
SCATTERED DEEP CONVECTION ACROSS THE WINDWARD ISLANDS. IN THIS
AREA EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM. OVER THE LEEWARD-VIRGIN ISLES TO EASTERN PUERTO IT IS TO
RESULT IN RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. AS
IT MOVES TO WESTERN VENEZUELA-EASTERN COLOMBIA EARLY ON SATURDAY
THIS IS TO SUSTAIN RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM... WHILE ACROSS THE ABC ISLES EXPECT ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15MM. AS IT PULLS ACROSS COLOMBIA ON
SUNDAY ALSO EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA
OF 25-50MM...WHILE OVER PANAMA IT IS TO THEN SUSTAIN RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM.

AN EASTERLY WAVE ALONG 84W IS INTERACTING WITH THE EASTERN PACIFIC
ITCZ AS IT MOVES ACROSS CENTRAL AMERICA. THROUGH SATURDAY MORNING
THIS IS TO TRIGGER A SURGE IN CONVECTION ALONG THE WEST COAST OF
NICARAGUA TO THE GULF OF FONSECA/EL SALVADOR...WHERE WE EXPECT
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. OVER
GUATEMALA-CHIAPAS IN SOUTHERN MEXICO IT IS TO THEN FAVOR RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40M...WHILE OVER
SOUTHERN-CENTRAL MEXICO IT IS TO FAVOR RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM AS IT INTERACTS WITH
RETROGRESSING TUTT OVER MEXICO/EASTERN PACIFIC.

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