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Tropical Discussion
 
(Latest Discussion - Issued 1831Z Jul 24, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EDT THU JUL 24 2014

DISCUSSION FROM JULY 24/00UTC: AT 250 HPA...A BROAD CELL OF THE
SUBTROPICAL RIDGE MAINTAINS ITS FOOTHOLD ACROSS THE SOUTHWEST USA
INTO THE NORTHERN STATES OF MEXICO. THIS IS TO ANCHOR ON A CLOSED
HIGH THAT IS TO MEANDER BETWEEN ARIZONA/NEW MEXICO. THE RIDGE
PATTERN IS TO PERSIST OVER THE NEXT FEW DAYS. A TUTT LOW LIES TO
THE SOUTH OF THIS RIDGE...WITH CLOSED CIRCULATION OVER SOUTHWEST
MEXICO. UNDER INFLUENCE OF THE RIDGE TO THE NORTH THE LOW
RETROGRESSES TO THE EASTERN PACIFIC EARLY THIS CYCLE. IT IS TO
THEN SLOWLY LIFT ACROSS THE BAJA PENINSULA THROUGH FRIDAY
EVENING/EARLY SATURDAY MORNING. MEANWHILE...THE LOW/TROUGH ALOFT
IS TO ENHANCE DIURNAL CONVECTION ACROSS COLIMA-NAYARIT-SINALOA
MEXICO AND SOUTHERN BAJA CALIFORNIA...WITH RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM. ACTIVITY THEN SPREADS NORTH
INTO SINALOA THROUGH FRIDAY EVENING. THE RIDGE ALOFT...AS IT
MEANDERS OVER NORTHERN MEXICO...IS TO VENT DIURNAL CONVECTION
ALONG THE SIERRA MADRE OCCIDENTAL OF MEXICO...TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THROUGH FRIDAY
EVENING THIS INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-40MM AS THE
TUTT LOW LIFTS ALONG THE COAST.

ANOTHER CELL OF THE SUBTROPICAL RIDGE EXTENDS ACROSS THE WESTERN
ATLANTIC/NORTH OF THE GREATER ANTILLES. AT 250 HPA THIS IS TO
ANCHOR ON A MEANDERING HIGH NEAR 29N 72W. THIS IS TO REMAIN NEARLY
STATIONARY THROUGH THURSDAY AFTERNOON...THEN STARTS TO ERODE LATER
ON FRIDAY AS A POLAR TROUGH AMPLIFIES ACROSS THE EASTERN USA.
HOWEVER...A WEAK CELL OF THIS RIDGE IS TO PERSIST OVER THE WESTERN
ATLANTIC THROUGH SATURDAY EVENING/SUNDAY MORNING. A TUTT LIES TO
THE SOUTHWEST OF THIS RIDGE...ORIGINATING ON A CLOSED LOW OVER
WESTERN CUBA WITH AXIS SOUTH TO BELIZE/THE YUCATAN PENINSULA. THE
RIDGE TO THE NORTH WILL STEER THIS LOW NORTH ACROSS WESTERN CUBA
TO THE EASTERN GULF OF MEXICO LATER ON THURSDAY/EARLY FRIDAY
MORNING. THIS THEN EVOLVES INTO A BROAD CYCLONIC CIRCULATION
ACROSS THE GULF OF MEXICO LATER ON SATURDAY. ACROSS THE NORTHERN
YUCATAN THIS IS TO ENHANCE SEA BREEZE CONVERGENCE TO RESULT IN
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM THROUGH FRIDAY
AFTERNOON. ACROSS WESTERN CUBA IT IS TO FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM. THROUGH FRIDAY AFTERNOON THIS
DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-20MM.

A THIRD TUTT LIES NORTH OF THE LESSER ANTILLES...WHILE CENTERING
ON A CLOSED LOW NEAR 28N 62W. TUTT PATTERN ALOFT IS EXPECTED TO
PERSIST THROUGH THE WEEKEND/EARLY NEXT WEEK...WITH CLOSED LOW TO
GENERALLY MEANDER TO THE NORTH OF 24N/25N. ALTHOUGH IT MAINTAINS A
WELL DEFINED CIRCULATION...SYSTEM IS NOT DEEP/STRONG ENOUGH TO PUT
A DENT ON TRADE WINDS CAP ACROSS THE NORTHEAST CARIBBEAN ISLES.
ANY ENHANCEMENT WITH THIS FEATURE IS TO GENERALLY LIMIT TO WESTERN
INTERIOR PORTIONS OF PUERTO RICO AS IT INTERACTS WITH A TROPICAL
WAVE EARLY IN THE CYCLE (SEE BELOW). OTHERWISE...IT IS NOT
FORECAST TO SUSTAIN ORGANIZED CONVECTION.

AT LOW LEVELS...BROAD RIDGE DOMINATES THE FLOW ACROSS THE ATLANTIC
BASIN INTO THE CARIBBEAN. THIS RIDGE FAVORS A TIGHT GRADIENT AND
STRONG EASTERLY WINDS ACROSS THE CARIBBEAN...WITH 850-800 HPA
WINDS PEAKING BETWEEN 35-45KT OVER THE SOUTHERN CARIBBEAN INTO
CENTRAL AMERICA. UNDER INFLUENCE OF THE RIDGE A TRADE WINDS CAP
PERSISTS ACROSS THE ISLAND CHAIN INTO THE EASTERN
CARIBBEAN...INHIBITING ORGANIZED DEEP CONVECTION.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
45W     50W    55W    59W    65W    70W    75W    79W     TW
64W     68W    71W    75W    78W    81W    84W    88W     TW
74W     77W    80W    83W    85W    88W    91W    94W     TW
96W     98W   101W   104W   107W   110W   112W   114W     TW

TROPICAL WAVE IS INITIALIZED ALONG 45W. THIS ENTERS FRENCH
GUIANA/AMAPA IN BRASIL-SURINAME LATER THIS EVENING...TO SUSTAIN
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. OVER
NORTHERN GUYANA/ORINOCO DELTA-SOUTHERN WINDWARD ISLANDS EXPECTING
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25XMM LATER ON
FRIDAY. ACROSS VENEZUELA MOST ACTIVE IS EXPECTED ACROSS AMAZONAS
TO LAKE MARACAIBO REGION DURING THE DAY ON SATURDAY...WITH
ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF 25-50MM...WHILE OVER THE
ABC ISLANDS EXPECTING RAINFALL AMOUNTS OF 05-10MM AND MAXIMA OF
15-25MM.

TROPICAL WAVE ALONG 64W SUSTAINS THE NORTHWARD MODULATION OF THE
ITCZ ACROSS THE FRENCH ISLANDS...WHERE WE EXPECT ADDITIONAL
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM THROUGH
FRIDAY MORNING. SOME INTERACTION IS POSSIBLE BETWEEN THIS WAVE AND
THE TUTT NORTH OF THE ISLANDS...TO ENHANCE CONVECTION ACROSS
PUERTO RICO/EASTERN HISPANIOLA...TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM OVER PUERTO RICO AND 10-15MM/DAY
AND MAXIMA OF 20-35MM ACROSS HISPANIOLA. ACROSS CENTRAL/WESTERN
VENEZUELA THE GLOBAL MODEL GUIDANCE CONSISTENTLY SHOW SCATTERED
CONVECTION WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM.
OVER JAMAICA-EASTERN CUBA IT IS TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM LATER ON FRIDAY. ACROSS COLOMBIA
TO THE DARIEN IN PANAMA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-40MM.

A WEAK TROPICAL WAVE IS INITIALIZED ALONG 74W. AS IT MOVES ACROSS
COLOMBIA IT IS TO SUSTAIN SCATTERED CONVECTION WITH ACCUMULATION
OF 10-15MM/DAY AND MAXIMA OF 20-35MM THROUGH THURSDAY EVENING.
ACROSS PANAMA TO COSTA RICA/SOUTHERN NICARAGUA IT IS TO INTERACT
WITH THE EASTERN PACIFIC ITCZ IN SUPPORT OF SCATTERED CONVECTION
WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-40MM. OVER EL
SALVADOR IT IS TO THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM.

TROPICAL WAVE ALONG 96W IS TO INTERACT WITH TUTT LOW OVER
SOUTHWEST MEXICO...TO TRIGGER SCATTERED CONVECTION ACROSS
OAXACA-GUERRERO WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
20-40MM THROUGH FRIDAY MORNING. ACROSS COLIMA-MICHOACAN/NAYARIT TO
CENTRAL MEXICO IT IS TO THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-25MM.

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