Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2
000
FXCA20 KWBC 221846
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
246 PM EDT FRI JUL 22 2016

AT 15 UTC TROPICAL STORM FRANK CENTERED NEAR 17.3N 107.4W...WITH
MINIMAL CENTRAL PRESSURE OF 1002 HPA AND MAXIMUM SUSTAINED WINDS
OF 45KT. SEE NHC BULLETIN FOR DETAILS.

TROPICAL DISCUSSION FROM JULY 22/12UTC: BROAD CELL OF THE
SUBTROPICAL RIDGE DOMINATES THE MID/UPPER LEVEL FLOW ACROSS THE
USA. EAST OF THIS RIDGE...A TROUGH LIES OVER THE WESTERN
ATLANTIC...WITH AXIS TO THE SOUTHWEST ALONG THE COAST TO THE
BAHAMAS. THROUGH SATURDAY EVENING THIS IS NOW FORECAST TO EVOLVE
INTO A CLOSED LOW. THE LOW MEANDERS WEST ACROSS FLORIDA DURING THE
DAY ON SUNDAY. THE MID/UPPER LEVEL CIRCULATION WILL SUPPORT AN
INDUCED TROUGH ACROSS THE BAHAMAS THAT MERGES WITH AN APPROACHING
TROPICAL WAVE. AS THEY COMBINE...THESE ARE TO FAVOR SCATTERED
CONVECTION. MEANWHILE...ACROSS THE BAHAMAS EXPECTING RAINFALL
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-40MM. THROUGH SUNDAY
THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-20MM AS THE UPPER
LOW MOVES WEST. OTHER CONVECTION IS TO BUILD ACROSS CUBA AS THE
TROUGH ALOFT ENHANCES SEA BREEZE RELATED CONVERGENCE. MOST ACTIVE
IS EXPECTED ON WESTERN-CENTRAL PORTIONS OF THE ISLAND WITH
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-40MM.

THE MID/UPPER LEVEL RIDGE OVER THE CONTINENT IS TO ANCHOR AT 500
HPA ON A CLOSED HIGH OVER NEW MEXICO. SOUTH OF THIS AXIS...AN
INVERTED SHORT WAVE TROUGH EXTENDS ACROSS THE GULF OF CORTEZ.
UNDER INFLUENCE OF THE RIDGE ALOFT THE TROUGH IS TO SLOWLY PULL TO
THE WEST-SOUTHWEST ACROSS THE BAJA PENINSULA EARLY ON SATURDAY
MORNING. MEANWHILE...THIS TROUGH IS TO ENHANCE DIURNAL CONVECTION
ALONG THE SIERRA MADRE OCCIDENTAL IN WESTERN MEXICO AND THE SIERRA
MADRE DEL SUR TO THE SOUTHWEST. ON THE SIERRA MADRE OCCIDENTAL
THIS IS TO RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-40MM THROUGH SATURDAY. ON THE SIERRA MADRE DEL SUR EXPECTING
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 35-70MM. ON SATURDAY
TO SUNDAY IT DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-20MM. LATER
ON SATURDAY ANOTHER SHORT WAVE TROUGH IS TO PULL ACROSS LOUISIANA
TO TEXAS...CROSSING INTO NORTHEAST MEXICO EARLY ON SUNDAY MORNING.
THIS IS LIKELY TO FAVOR AN INCREASE IN CONVECTION ALONG THE RIO
BRAVO BETWEEN COAHUILA-TAMAULIPAS LATER DURING THE WEEKEND...WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM.

SOUTH OVER THE CARIBBEAN...A TUTT EXTENDS NORTH ACROSS EL
SALVADOR/HONDURAS TO THE WESTERN CARIBBEAN. THE TROUGH IS SHEARING
NORTH AND WEST...WITH SOME OF THE ENERGY PULLING ACROSS CUBA WHILE
THE MAIN BODY CONTINUES WEST ACROSS BELIZE/GUATEMALA TO THE
SOUTHERN STATES OF MEXICO. AS IT SHEARS...THE TROUGH IS FORECAST
TO NEARLY DISSIPATE THROUGH SUNDAY EVENING. MEANWHILE...THIS IS TO
ENHANCE DIURNAL CONVECTION ACROSS NORTHERN CENTRAL AMERICA...TO
RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM.
ON SATURDAY TO SUNDAY THIS DECREASES TO 00-05MM/DAY AND MAXIMA OF
10MM. ON THE SOUTHERN-CENTRAL STATES OF MEXICO THE RETROGRESSING
TROUGH IS TO THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-25MM.

WANING CELL OF THE BERMUDA RIDGE LIES NORTH OF THE ISLANDS...WITH
MID LEVEL AXIS EXPECTED TO COLLAPSE LATER TODAY/EARLY ON SATURDAY.
A SECONDARY CELL IS TO GRADUALLY BUILD FROM THE EAST...TO SPAN
ACROSS THE EASTERN-CENTRAL ATLANTIC BY MIDDAY ON SATURDAY. AS IT
BUILDS...THE RIDGE DISPLACES A TUTT TO THE NORTHEAST CARIBBEAN
LATER TODAY...AND ACROSS PUERTO RICO DURING THE DAY ON SATURDAY.
BUT AS IT IS TO REMAIN CUT OFF FROM THE FLOW...THE TROUGH IS TO
NEARLY FILL AS IT PULLS ACROSS THE DOMINICAN REPUBLIC ON SUNDAY.
PERSISTENT MID/UPPER LEVEL RIDGE PATTERN IS TO FAVOR A CAP
INVERSION ACROSS THE EASTERN CARIBBEAN. THIS RELAXES A LITTLE BIT
ON SATURDAY AS THE TUTT PULLS ACROSS THE ISLANDS. THIS WILL
COMBINE WITH BRISK EASTERLY TRADES TO FAVOR AN INCREASE IN
GENERATION OF STREAMERS AND SHALLOW CONVECTIVE CELLS THAT ARE TO
AFFECT THE LEEWARD-VIRGIN ISLES AND PUERTO RICO FROM TIME TO TIME
LATER DURING THE WEEKEND INTO EARLY NEXT WEEK.

NET RELATED CONVECTION ACROSS NORTHERN SOUTH AMERICA IS TO AFFECT
THE SOUTHERN GUIANAS-VENEZUELA AND PORTIONS OF COLOMBIA. ACROSS
THE GUIANAS IT IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM...WHILE ACROSS VENEZUELA TO COLOMBIA EXPECTING
RAINFALL ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM. MOST
ACTIVE IS EXPECTED TO THE SOUTH OF 06N. ON THE WESTERN PLAINS AND
ANDEAN REGION...UNDER INFLUENCE OF THE PANAMANIAN LOW...A MOIST
WESTERLY FLOW IS EXPECTED DURING THE NEXT FEW DAYS. THIS WILL
ENHANCE CONVECTION TO RESULT IN RAINFALL AMOUNTS OF 15-20MM/DAY
AND MAXIMA OF 25-50MM. THROUGH SATURDAY...HOWEVER...THIS WILL
DECREASE TO 10-15MM/DAY AND MAXIMA OF 20-35MM.

TROPICAL/EASTERLY WAVES INITIALED AT 12UTC.
INITIAL    24    36    48    60    72    84    96      TYPE
46W       48W   51W   54W   58W   61W   64W   67W      EW
53W       57W   60W   64W   67W   71W   75W   78W  TUTT INDUCED
78W       82W   85W   88W   90W   93W   96W  100W      TW
87W       89W   91W   93W   96W   DISSIPATES      TUTT INDUCED
100W     102W  104W  106W  DISSIPATES                  TW

AN EASTERLY WAVE IS INITIALIZED ALONG 46W. THIS REACHES THE
EASTERN CARIBBEAN ISLES LATER ON SUNDAY TO TRIGGER ISOLATED TO
SCATTERED SHOWERS...WITH RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM.

RETROGRESSING TUTT WILL INDUCE A PERTURBATION IN THE EASTERLY
TRADES THAT MOVES OVER THE LEEWARD ISLES EARLY ON SATURDAY
MORNING. THIS IS A WEAK PERTURBATION THAT IS TO ONLY FAVOR
ISOLATED CONVECTION...WITH RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM AS IT PULLS ACROSS THE LEEWARD TO THE VIRGIN ISLES.
THIS SPREADS WEST ACROSS THE VIRGIN ISLES TO PUERTO RICO EARLY ON
SUNDAY WHERE IT FAVORS SIMILAR AMOUNTS. ACROSS THE DOMINICAN
REPUBLIC THIS INCREASES TO 05-10MM/DAY AND MAXIMA OF 15MM LATER IN
THE DAY.

TROPICAL WAVE ALONG 78W IS TO TRIGGER SCATTERED CONVECTION ACROSS
CENTRAL/WESTERN CUBA THROUGH SATURDAY MORNING...WITH RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. IT IS TO ALSO
ENHANCE CONVECTION ACROSS THE BAHAMAS AS IT INTERACTS WITH THE
TUTT ALOFT...TO RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-40MM. OVER PANAMA-COSTA RICA AND SOUTHERN NICARAGUA
IT IS TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-40MM. OVER EL SALVADOR-SOUTHERN HONDURAS IT WILL SUSTAIN
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM...WHILE OVER
NORTHERN HONDURAS-BELIZE-GUATEMALA TO THE YUCATAN IT WILL SUSTAIN
RAINFALL OF 05-10MM/DAY AND MAXIMA OF 15-25MM. ON THE SOUTHERN
STATES OF MEXICO IT IS TO THEN TRIGGER RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM.

A WANING TUTT INDUCED PERTURBATION IN THE EASTERLY TRADES LIES
ALONG 87W. AS THE TUTT ALOFT WEAKENS THIS TROUGH IS TO ALSO
WEAKEN...AND IT IS LIKELY TO DISSIPATE AS IT PULLS ACROSS
SOUTHERN-CENTRAL MEXICO. OVER GUATEMALA-YUCATAN TO SOUTHERN MEXICO
IT IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-25MM THROUGH SATURDAY.

TROPICAL WAVE ALONG 100W IS FORECAST TO DISSIPATE LATER ON SUNDAY.
MEANWHILE...OVER SOUTHWEST MEXICO THIS IS TO FAVOR RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 35-70MM.

CABANERIT...INAMEH (VENEZUELA)
CONTRERAS...IMN (COSTA RICA)
CASTILLO...UCR (COSTA RICA)
DAVISON...WPC (USA)

$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.