Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4
838
FXCA20 KWBC 271827
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
227 PM EDT MON MAR 27 2017

TROPICAL DISCUSSION FROM MARCH 27/12 UTC: A DEEP MID/UPPER LEVEL
TROUGH MOVES ACROSS CALIFORNIA TO THE WESTERN USA LATER
TODAY/EARLY TUESDAY MORNING. AS IT MOVES INLAND THE TROUGH WILL
PRESS AGAINST A RIDGE TO THE EAST...THAT IS TO EXTEND NORTH FROM
MEXICO TO THE CENTRAL USA. THROUGH WEDNESDAY EVENING THE TROUGH IS
TO MEANDER FARTHER EAST INTO THE CENTRAL USA/MISSISSIPPI VALLEY.
AT LOW LEVELS...THE ASSOCIATED FRONT IS TO GENERALLY CONFINE TO
THE SOUTHWEST USA/MEXICO BORDER...WITH BEST MOISTURE CONVERGENCE
TO TAKE PLACE ALONG THE FRONT TO THE NORTH. ACROSS MEXICO
CONVECTION WILL LIMIT TO THE SOUTHWEST STATES OF
COLIMA-NAYARIT-GUERRERO...WHERE UNDER INFLUENCE OF A MOIST ONSHORE
FLOW...SCATTERED DIURNAL CONVECTION IS TO CLUSTER ALONG THE SIERRA
MADRE DEL SUR...TO SUSTAIN RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM.

OVER THE WESTERN ATLANTIC...A TROUGH EXTENDS BETWEEN 80W-60W AND
TO THE NORTH OF 20N...WHILE ANCHORING ON A CLOSED LOW SOUTH OF
BERMUDA. SHORT WAVE TROUGH EXITING THE EASTERN USA EARLY ON
TUESDAY IS TO MERGE WITH THE REMNANTS OF THIS TROUGH EARLY ON
WEDNESDAY MORNING. AS THEY COMBINE...THEY WILL EVOLVE INTO A BROAD
TROUGH OVER THE CENTRAL ATLANTIC WHILE ANCHORING ON A CLOSED LOW
AT 32N 57W. AS THE LOW/TROUGH DEEPENS ON TUESDAY TO WEDNESDAY...A
250 HPA JET MAXIMA ROUNDING THE TROUGH IS TO INTENSIFY WHILE
MEANDERING NORTH OF PUERTO RICO/HISPANIOLA. ON ITS RIGHT ENTRANCE
REGION...THIS WILL FAVOR AN UPPER DIVERGENT PATTERN THAT IS TO
VENT DIURNAL CONVECTION. ON WEDNESDAY...AS THE TROUGH PULLS
AWAY...A RIDGE WILL SLOWLY BUILD FROM THE WEST ACROSS THE GREATER
ANTILLES TO THE NORTHERN CARIBBEAN ISLES. THE BUILDING RIDGE IS TO
THEN STRENGTHEN THE TRADE WINDS CAP WHILE SUSTAINING EROSION OF
AVAILABLE WATER LATER IN THE WEEK. AT LOW LEVELS...UNDER THE
INFLUENCE OF THE MID LEVEL COLD CORE LOW...A WARM CORE CYCLONE
FORMED NORTH OF HISPANIOLA/EAST OF THE TURKS AND CAICOS ISLES.
THIS IS TO REMAIN NEARLY STATIONARY OVER THE NEXT TWO DAYS...THEN
STARTS TO PULL TO THE EAST-NORTHEAST ON WEDNESDAY. THE DEEP TROUGH
NORTH OF THE ISLANDS FAVORS AN INDUCED/INVERTED TROUGH ACROSS THE
CARIBBEAN BETWEEN WESTERN VENEZUELA AND HISPANIOLA. THE TROUGH
SUSTAINS A MOIST SOUTHEASTERLY FLOW ACROSS THE ISLAND CHAIN TO
PUERTO RICO AND THE VIRGIN ISLES. THE MOIST ADVECTIVE PATTERN WILL
PERSIST DURING THE NEXT TWO DAYS. ON WEDNESDAY...AS THE LOW
MEANDERS AWAY...PREVAILING EASTERLY TRADES RETURN TO THE ISLAND
CHAIN/EASTERN CARIBBEAN... CUTTING THE INFLOW OF MOIST TROPICAL
AIR. MEANWHILE...THIS IS TO FEED CONVECTIVE DEVELOPMENT. ACROSS
THE DOMINICAN REPUBLIC EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-20MM THROUGH TUESDAY MORNING...AND 00-05MM/DAY
AND MAXIMA OF 10MM THEREAFTER. ACROSS PUERTO RICO EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM...WITH
LOCALLY HIGHER AMOUNTS POSSIBLE ON TUESDAY AS THE JET ALOFT
INTENSIFIES AS IT APPROACHES THE NORTHEAST CARIBBEAN ISLES. ON
WEDNESDAY THIS DECREASES TO 00-05MM/DAY AND MAXIMA OF 10MM. OVER
THE VIRGIN ISLES EXPECTING RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM. OVER THE ISLAND CHAIN INITIALLY EXPECTING RAINFALL
ACCUMULATION OF 00-05MM/DAY AND WIDELY ISOLATED MAXIMA OF 10MM. ON
TUESDAY IT WILL INCREASE TO 05-10MM/DAY AND MAXIMA OF
15-20MM...WHILE ON WEDNESDAY THE MAXIMA PEAKS AT 15MM.

AT 250 HPA...A CELL OF THE SUBEQUATORIAL RIDGE DOMINATES THE FLOW
ACROSS THE TROPICAL ATLANTIC-NORTHERN SOUTH AMERICA-EASTERN
PACIFIC/SOUTHERN CENTRAL AMERICA. RIDGE PATTERN ALOFT IS TO
PERSIST NEARLY UNCHANGED OVER THE NEXT THREE DAYS. ACROSS THE
GUIANAS DIURNAL CONVECTION IS TO FAVOR RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM. OVER SOUTHERN-CENTRAL VENEZUELA
AND AMAZONIA OVER COLOMBIA... MEANWHILE...EXPECTING RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM. THROUGH TUESDAY THIS
WILL DECREASE TO 10-15MM/DAY AND MAXIMA OF 20-35MM. ON THE ANDEAN
REGION AND WESTERN PLAINS OF COLOMBIA EXPECTING RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ON THE SIERRA NEVADA TO THE
NORTH AND NORTHWEST VENEZUELA INITIALLY EXPECTING RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH WEDNESDAY THIS WILL
INCREASE TO MAXIMA OF 20-40MM. THE RIDGE ALOFT IS TO ALSO VENT
DIURNAL CONVECTION ACROSS SOUTHERN CENTRAL AMERICA...WITH MOST
ACTIVE EXPECTED OVER COSTA RICA AND WESTERN PANAMA...WITH RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. THROUGH WEDNESDAY THE
MAXIMA INCREASES TO 15-20MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL   24     36     48     60     72     84     96       TYPE
39W      42W    44W    47W    49W    52W    54W    56W       TW

A TROPICAL WAVE IS INITIALIZED ALONG 39W AND SOUTH OF 14N. THIS
ENTERS FRENCH GUIANA EARLY ON WEDNESDAY MORNING...TO FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM. THROUGH
THURSDAY CONVECTION WILL SPREAD ACROSS SURINAME TO GUYANA...TO
TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM.

JIMENEZ...IMN (COSTA RICA)
SUBRATH-ALI...TTMS (TRINIDAD AND TOBAGO)
DAVISON/GALVEZ...WPC (USA)
$$





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