Prognostic Meteorological Discussion
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FXCA20 KWBC 231832
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
232 PM EDT TUE SEP 23 2014

DISCUSSION FROM SEPTEMBER 23/00UTC: AT 250 HPA...A HIGH OVER
SOUTHERN BAJA CALIFORNIA/SINALOA ANCHORS A RIDGE ACROSS MEXICO AND
THE SOUTHWEST USA. THE MODELS FORECAST UPPER RIDGE PATTERN TO
GRADUALLY CRUMBLE THROUGH THURSDAY EVENING AS A TROUGH DEEPENS
ACROSS TEXAS-ARIZONA TO THE NORTHERN MEXICO. EARLY IN THE
CYCLE...THE RIDGE ALOFT IS TO VENT DIURNAL CONVECTION ALONG THE
SIERRA MADRE OCCIDENTAL. IN THIS AREA INITIALLY EXPECTING RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON
WEDNESDAY...MAXIMA INCREASES TO 30-60MM...BUT THROUGH THURSDAY
EVENING THIS DECREASES TO 10-15MM/DAY AND MAXIMA OF 20-30MM. OVER
NORTHEAST MEXICO...MOST ACTIVE CONVECTION IS EXPECTED BETWEEN
SOUTHERN TAMAULIPAS/SAN LUIS POTOSI-VERACRUZ TO HIDALGO/PUEBLA
THROUGH WEDNESDAY MORNING...WITH ACCUMULATION OF 15-20MM/DAY AND
MAXIMA OF 25-50MM. AS MID/UPPER TROUGH DEEPENS ACROSS NORTHERN
MEXICO...THE MAXIMA INCREASES TO 30-60MM ON WEDNESDAY. ON
THURSDAY...HOWEVER...IT DECREASES TO 10-15MM/DAY AND MAXIMA OF
20-40MM. ON THE SIERRA MADRE DEL SUR AND CENTRAL STATES OF
MEXICO...A LOW ALONG THE ITCZ IS TO FAVOR A MOIST ADVECTIVE
PATTERN. NOTE THAT THE NHC IS MONITORING THIS FEATURE FOR POSSIBLE
TROPICAL CYCLONE FORMATION. MEANWHILE...THIS IS TO ENHANCE
MOISTURE TRANSPORT/COASTAL CONVERGENCE...WITH RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 30-60MM. THROUGH WEDNESDAY THIS
DECREASES TO 10-15MM/DAY AND MAXIMA OF 20-40MM.

EAST OF THE CONTINENTAL RIDGE...AT 250 HPA...A LONG WAVE TROUGH
EXTENDS ACROSS THE EASTERN USA TO THE YUCATAN PENINSULA/GUATEMALA.
BUT AS THE RIDGE WEAKENS TO THE WEST...THE TROUGH IS TO GRADUALLY
WEAKEN THROUGH THURSDAY MORNING. AT LOW LEVELS...THIS SUSTAINS A
TROUGH ACROSS THE EASTERN USA/WESTERN ATLANTIC...AND AN INDUCED
INVERTED TROUGH OVER THE EASTERN GULF OF MEXICO/FLORIDA PENINSULA.
THIS IS ENHANCING LOW LEVEL MOISTURE CONVERGENCE FROM WESTERN CUBA
TO THE NORTHWEST BAHAMAS. ACROSS THE NORTHWEST-CENTRAL BAHAMAS
EXPECTING SCATTERED CONVECTION TO SUSTAIN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM...WHILE OVER CUBA EXPECT
15-20MM/DAY AND MAXIMA OF 25-50MM. THE TROUGH ALOFT IS TO ENHANCE
SEA BREEZE CONVERGENCE ACROSS BELIZE-YUCATAN PENINSULA-GUATEMALA
AND CHIAPAS/TABASCO IN SOUTHERN MEXICO THROUGH TUESDAY
EVENING...WITH RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM.

FURTHERMORE...A WEAK TUTT EXTENDS ACROSS THE CAYMAN ISLES/WESTERN
CARIBBEAN. THIS TROUGH IS CUT OFF FROM THE FLOW...AND EXPECTED TO
GRADUALLY WEAKENING AS IT MEANDERS NORTH ACROSS CUBA EARLY ON
WEDNESDAY. OVER THE CAYMAN ISLES...MEANWHILE...THIS IS TO ENHANCE
CONVECTIVE INSTABILITY TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-30MM. ACROSS CENTRAL-EASTERN CUBA...AS IT
INTERACTS WITH A TROPICAL WAVE...EXPECTING RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM.

A BROAD CELL OF THE SUBTROPICAL RIDGE LIES NORTH OF THE GREATER
ANTILLES INTO THE WESTERN ATLANTIC...WHILE CENTERING ON A 250 HPA
HIGH NEAR 25N 66W. SOUTH OF THIS AXIS...OVER THE CENTRAL
CARIBBEAN...A CELL OF THE SUBEQUATORIAL RIDGE EXTENDS BETWEEN
CENTRAL AMERICA AND 70W...WHILE ANCHORING ON A CLOSED HIGH NEAR LA
GUAJIRA PENINSULA. AS TROUGH OVER THE EASTERN USA/GULF OF MEXICO
WEAKENS...THE SUBTROPICAL RIDGE IS TO MEANDER WEST INTO THE
BAHAMAS/OFF THE EAST COAST OF THE USA...WHILE THE SUBEQUATORIAL
RIDGE MOVES TO THE WESTERN CARIBBEAN/CENTRAL AMERICA. THIS IS TO
STRENGTHEN THE TRADE WINDS CAP ACROSS THE BAHAMAS-CUBA-JAMAICA-THE
CAYMAN ISLES...LEADING TO GRADUAL EROSION OF AVAILABLE MOISTURE.

AS THE UPPER LEVEL RIDGE RELOCATES TO THE WESTERN ATLANTIC...IT IS
TO ALLOW A TUTT OVER THE CENTRAL ATLANTIC TO RETROGRESS TO THE
EASTERN CARIBBEAN. THE TUTT ANCHORS ON A CLOSED LOW NEAR 24N 56W.
THIS LOW EXTENDS A SHORT WAVE TROUGH TO THE NORTHEAST CARIBBEAN.
MODELS MADE CORRECTIONS TO PREVIOUS RUN...NOW FORECASTING THE LOW
TO REMAIN TO THE NORTH-NORTHEAST OF THE LESSER ANTILLES. BUT AS
THE RIDGE TO THE WEST EVOLVES...IT WILL ALLOW BASE OF THE TROUGH
TO GRADUALLY DEEPEN ACROSS THE NORTHEAST/EASTERN CARIBBEAN TO
NORTHERN SOUTH AMERICA LATER ON THURSDAY. THE DEEP MID/UPPER LEVEL
TROUGH IS TO INTERACT WITH THE ATLANTIC ITCZ...TO SUSTAIN A MOIST
PLUME ACROSS THE FRENCH ISLES/NORTHEAST CARIBBEAN. EARLY IN THE
PERIOD PWAT IS TO PEAK AT 50-60MM. ALTHOUGH HIGH MOISTURE CONTENT
IS TO PERSIST ACROSS THE FRENCH ISLES...OVER PUERTO RICO/VIRGIN
ISLES-EASTERN HISPANIOLA IT DECREASES TO 40-45MM. THIS WILL BE
ENOUGH TO HELP SUSTAIN DEEP CONVECTION. ACROSS THE LEEWARD/FRENCH
ISLES EXPECTING ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF 25-50MM.
OVER PUERTO RICO AND THE DOMINICAN REPUBLIC EXPECTING RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM THROUGH WEDNESDAY
MORNING...AND 10-15MM/DAY AND MAXIMA OF 20-40MM THEREAFTER. OVER
NORTHERN SOUTH AMERICA...THE SUBEQUATORIAL RIDGE IS TO INITIALLY
VENT DEEP CONVECTION ALONG THE NEAR EQUATORIAL TROUGH BETWEEN
COLOMBIA AND NORTHWEST VENEZUELA...WITH RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM...DECREASING TO 10-15MM/DAY AND
MAXIMA OF 20-35MM. ACROSS PANAMA-COSTA RICA...ITCZ CONVECTION IS
TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
48W     50W    52W    53W    54W    55W    56W    56W    TUTT
INDCD.
69W     71W    72W    74W    76W    78W    79W    81W     TW
82W     83W    84W    85W    86W    88W    89W    90W     TW

TUTT INDUCED PERTURBATION ALONG 48W IS NOW FORECAST TO REMAIN
ALONG THE ATLANTIC ITCZ.

TROPICAL WAVE ALONG 69W CONTINUES TO INTERACT WITH THE TUTT OVER
THE NORTHEAST CARIBBEAN. AS THE WAVE MOVES ACROSS HISPANIOLA IT IS
TO FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM ON
TUESDAY-WEDNESDAY. AS IT ENTERS JAMAICA IT IS TO THEN FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. OVER
NORTHWEST VENEZUELA-NORTHERN COLOMBIA...IN INTERACTION WITH THE
NET...EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM. ACROSS PANAMA IT IS TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM.

TROPICAL WAVE ALONG 82W MOVES ACROSS COSTA RICA TO EASTERN
NICARAGUA/ NORTHEAST HONDURAS THROUGH WEDNESDAY MORNING...TO
SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM.
ACROSS THE CAYMAN ISLANDS IT IS TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM. OVER HONDURAS/EL SALVADOR IT IS
TO FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM...WHILE OVER GUATEMALA/BELIZE IT IS TO ALSO SUSTAIN
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM.

VALVERDE...IMN (COSTA RICA)
MEDINA...ONAMET (REPUBLICA DOMINICANA)
DAVISON...WPC (USA)
$$





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