Prognostic Meteorological Discussion
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FXCA20 KWBC 011811
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
211 PM EDT TUE SEP 01 2015

DISCUSSION FROM SEP 01/12 UTC: A MID/UPPER LEVEL RIDGE EXTENDS
SOUTH-TO-NORTH ACROSS WESTERN MEXICO TO THE SOUTHWEST USA...WITH
AXIS TO ANCHOR ON A 250 HPA HIGH OVER NORTHWEST MEXICO. A TROUGH
TO THE WEST PRESSES AGAINST THIS AXIS...FAVORING A LONG FETCH
SOUTHWESTERLY FLOW ACROSS BAJA PENINSULA-SONORA MEXICO TO THE
SOUTHWEST USA. SHORT WAVE VORTICES EMBED IN THIS FLOW. AS THEY
STREAM ACROSS NORTHWEST MEXICO THIS WILL COMBINE WITH DIURNAL
HEATING TO FAVOR DEEP LAYER CONVECTIVE INSTABILITY. ACROSS
SOUTHERN BAJA PENINSULA THIS IS TO FAVOR SCATTERED CONVECTION WITH
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. OVER SONORA
MEXICO...MEANWHILE...EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-45MM. THROUGH THURSDAY THIS DECREASES TO 10-15MM/DAY
AND MAXIMA OF 20-35MM.

ANOTHER TROUGH BOUNDS THE EASTERN FRINGES OF THE MID/UPPER LEVEL
RIDGE... WITH AXIS SOUTH-SOUTHWEST TO THE NORTHEAST STATES OF
MEXICO. THE RIDGE DISPLACES THIS AXIS EAST INTO THE WESTERN GULF
OF MEXICO LATER ON WEDNESDAY. THE TROUGH IS TO THEN GRADUALLY
WEAKEN AS ASSOCIATED SHORT WAVE ENERGY SHEARS TO THE
SOUTH-SOUTHWEST ACROSS THE CENTRAL/SOUTHERN STATES OF MEXICO.
EARLY IN THE CYCLE THE TROUGH WILL ENHANCE CONVECTION ACROSS
NORTHEAST MEXICO TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM. OVER CENTRAL-SOUTHWEST
MEXICO...MEANWHILE...EXPECT RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 30-60MM. ACROSS THE SOUTHERN STATES OF MEXICO/THE
YUCATAN EXPECT DIURNAL CONVECTION TO FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM.

ALSO AT 250 HPA...AN EAST-TO-WEST TROUGH OVER THE NORTHERN
CARIBBEAN SEPARATES THE SUBTROPICAL RIDGE OVER THE WESTERN
ATLANTIC FROM A CELL OF THE SUBEQUATORIAL RIDGE OVER THE EASTERN
CARIBBEAN. GENERAL TENDENCY IS FOR THE SUBTROPICAL RIDGE PATTERN
TO STRENGTHEN THROUGH WEDNESDAY...WITH MID/UPPER LEVEL AXIS
BUILDING SOUTH ACROSS THE GREATER ANTILLES TO THE NORTHERN
CARIBBEAN. THE OPPOSITE IS EXPECTED TO THE SOUTH...WITH THE
SUBEQUATORIAL RIDGE OVER THE CARIBBEAN TO NEARLY COLLAPSE EARLY ON
THURSDAY.

UNDER THE SHEAR DEFORMATION FROM THE BUILDING SUBTROPICAL
RIDGE...THE TUTT TO THE SOUTH IS TO SPLIT IN TWO DISTINCT
VORTICES. THE WESTERNMOST EVOLVES INTO A CUT OFF LOW NEAR THE
CAYMAN ISLES...WHERE IT IS TO REMAIN WHILE GRADUALLY WEAKENING
THROUGH FRIDAY. MEANWHILE...THIS IS TO SUSTAIN AN INVERTED MID
LEVEL TROUGH THAT PUSHES WEST INTO CENTRAL AMERICA. THIS IS LIKELY
TO FAVOR AN INCREASE IN DIURNAL CONVECTION ACROSS PORTIONS OF
HONDURAS-EL SALVADOR AND NICARAGUA. IN THIS AREA INITIALLY
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM.
THIS INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-30MM ON THURSDAY TO
FRIDAY. OVER PANAMA-COSTA RICA TO SOUTHERN NICARAGUA EXPECT
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM...WITH
HIGHER AMOUNTS IN ASSOCIATION WITH TROPICAL WAVES. ACROSS WESTERN
CUBA...UNDER INFLUENCE OF THE TUTT LOW...EXPECT RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-45MM.

THE OTHER TUTT LOW IS TO MEANDER OVER THE VIRGIN ISLES/NORTHERN
LEEWARD ISLES THROUGH WEDNESDAY MORNING...TO THEN SETTLE OVER THE
NORTHEAST CARIBBEAN WHILE EXTENDING A SHORT WAVE TROUGH TO
VENEZUELA. AS THE TROUGH MEANDERS TO THE EAST AND SOUTH A
MID/UPPER LEVEL CONVERGENT PATTERN IS TO ESTABLISH THROUGH MIDDAY
ON WEDNESDAY...LEADING TO RAPID EROSION OF AVAILABLE MOISTURE
ACROSS PUERTO RICO-HISPANIOLA. ALTHOUGH TUTT IS FORECAST TO EVOLVE
INTO A WELL DEFINED FEATURE OVER THE EASTERN CARIBBEAN...IT WILL
CONFINE TO ATMOSPHERE ABOVE 400 HPA...THUS HAVING LITTLE IMPACT ON
WEATHER CONDITIONS ACROSS THE FRENCH-LEEWARD ISLANDS. CONVECTIVE
ENHANCEMENT IS TO THEN LIMIT TO NORTHERN VENEZUELA WHERE IN
INTERACTION WITH THE NET IT IS TO FAVOR SCATTERED CONVECTION. IN
THIS AREA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-30MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
63W     67W    71W    75W    79W    82W    85W    88W        TW
76W     79W    81W    83W    86W    88W    90W    92W        TW
91W     93W    95W    98W   101W   103W   104W   105W        TW

TROPICAL WAVE ALONG 63W CONTINUES TO INTERACT WITH THE TUTT TO THE
NORTH AS IT PULLS ACROSS PUERTO RICO TO EASTERN HISPANIOLA. THIS
WILL ENHANCE DIURNAL CONVECTION TO RESULT IN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM/DAY IN POTENTIALLY SEVERE
CONVECTION. AS IT PULLS ACROSS HAITI... NEGATIVE INTERACTION WITH
BUILDING MID LEVEL RIDGE ALOFT WILL LEAD TO EROSION OF AVAILABLE
MOISTURE AND SHARP DECREASE IN CONVECTIVE DEVELOPMENT. MOST ACTIVE
IS EXPECTED TO THE SOUTH ALONG THE NEAR EQUATORIAL TROUGH OVER
VENEZUELA-COLOMBIA. ACROSS CENTRAL VENEZUELA EXPECT RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM...WHILE OVER
NORTHWEST VENEZUELA TO NORTHERN COLOMBIA IT IS TO TRIGGER RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM ON WEDNESDAY. AS IT
MOVES ACROSS PANAMA TO COSTA RICA THIS IS TO THEN INTERACT WITH
THE ITCZ IN SUPPORT OF RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA
OF 30-60MM. OVER EASTERN NICARAGUA IT IS TO THEN TRIGGER RAINFALL
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM.

TROPICAL WAVE ALONG 76W IS IN PHASE WITH THE CENTRAL CARIBBEAN
TUTT LOW. THIS IS TO ENHANCE CONVECTIVE DEVELOPMENT ACROSS CUBA TO
RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM.
ACROSS COLOMBIA TO EASTERN PANAMA EXPECT RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM WHILE ALSO INDUCING GRADUAL
INTENSIFICATION OF THE PANAMANIAN LOW. OVER WESTERN PANAMA-COSTA
RICA TO SOUTHERN NICARAGUA EXPECT RAINFALL AMOUNTS OF 15-20MM/DAY
AND MAXIMA OF 25-50MM...WHILE OVER EASTERN NICARAGUA/NORTHEAST
HONDURAS EXPECT RAINFALL ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
20-35MM. OVER EL SALVADOR-SOUTHERN HONDURAS EXPECT THIS TO TRIGGER
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM EARLY ON
THURSDAY MORNING...WHILE OVER GUATEMALA EXPECT RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM.

TROPICAL WAVE ALONG 91W IS TO ALSO INTERACT WITH MEANDERING
MID/UPPER LEVEL TROUGH OVER THE WESTERN GULF-CENTRAL MEXICO. AS
THE WAVE MOVES FROM SOUTHERN-CENTRAL MEXICO OVER THE NEXT COUPLE
OF DAYS IT IS TO FAVOR SCATTERED DEEP CONVECTION WITH RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM.


SALMON...MS (ANTIGUA AND BARBUDA)
CABRERA...ONAMET (THE DOMINICAN REPUBLIC)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)

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