Prognostic Meteorological Discussion
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FXCA20 KWBC 031825
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
225 PM EDT THU SEP 03 2015

AT 15 UTC TROPICAL STORM KEVIN CENTERED NEAR 17.9N 115.6W...WITH
MAXIMUM SUSTAINED WINDS OF 45KT AND CENTRAL PRESSURE OF 1000 HPA.
THE STORM IS MOVING TO THE NORTH OR 350 DEGREES AT 05KT. SEE NHC
BULLETING FOR OFFICIAL FORECAST.

DISCUSSION FROM SEP 03/12 UTC: MID/UPPER LEVEL RIDGE OVER WESTERN
PORTIONS OF THE DOMAIN DOMINATES THE FLOW ACROSS CENTRAL/NORTHERN
MEXICO TO THE WESTERN USA. AT 250 HPA A HIGH NEAR COLIMA/NAYARIT
IN SOUTHWEST MEXICO IS TO INITIALLY ANCHOR THIS AXIS. THROUGH
MIDDAY ON SATURDAY THIS LIFTS TO THE TEXAS PANHANDLE. THE RIDGE IS
TO VENT DIURNAL CONVECTION ALONG THE SIERRA MADRE OCCIDENTAL OVER
WESTERN MEXICO...WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-20MM. TS KEVIN MEANDERS TO THE SOUTH OF THIS
RIDGE...WITH THE NHC FORECASTING THIS STORM TO GRADUALLY WEAKEN TO
A DEPRESSION EARLY ON SUNDAY MORNING.

A WANING TUTT LOW OVER THE WESTERN GULF BOUNDS THE EASTERN FRINGES
OF THIS RIDGE. AS THE RIDGE HOLDS IT IS TO STEER THIS FEATURE TO
THE SOUTH-SOUTHWEST ACROSS MEXICO. THROUGH LATER TODAY THE WANING
LOW MOVES TO VERACRUZ/CENTRAL MEXICO...AND EARLY ON SATURDAY IT
PULLS ACROSS THE SOUTHWEST STATES TO THE EASTERN PACIFIC. AT LOW
LEVELS...HEAT TROUGH OVER MEXICO WILL ENHANCE MOISTURE TRANSPORT
INLAND. THIS WILL COMBINE WITH INFLOW OF MID/UPPER LEVEL VORTICITY
TO FAVOR AREAS OF MODERATE TO HEAVY CONVECTION ON THE CENTRAL
STATES OF VERACRUZ-PUEBLA-MEXICO/DF AND INTO THE SOUTHWEST STATES
OF COLIMA-NAYARIT-GUERRERO. THE COLD CORE UPPER TROUGH IS TO
ENHANCE CONVECTIVE INSTABILITY IN THIS AREA TO LIKELY FAVOR
GENERATION OF SEVERE THUNDERSTORMS DURING THE AFTERNOON HOURS. IN
THIS AREA EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
35-70MM THROUGH FRIDAY MORNING...AND MAXIMA OF 25-50MM ON FRIDAY
TO SATURDAY.

FARTHER EAST...THE SUBTROPICAL RIDGE SPANS FROM THE CENTRAL GULF
OF MEXICO TO THE NORTHERN CARIBBEAN ISLES. AT 500 HPA THIS IS TO
ANCHOR ON A CLOSED HIGH OVER SOUTH FLORIDA. AN AMPLIFYING POLAR
TROUGH OVER THE EASTERN USA/WESTERN ATLANTIC IS TO PRESS AGAINST
THIS RIDGE. THIS IS TO THEN INDUCE GRADUAL EROSION OF MID/UPPER
LEVEL RIDGE PATTERN THROUGH MIDDAY ON SATURDAY. EARLY IN THE CYCLE
THE BROAD RIDGE IS TO FAVOR A FAIRLY STRONG CAP INVERSION ACROSS
THE BAHAMAS...PORTIONS OF CUBA...HISPANIOLA TO PUERTO RICO/VIRGIN
ISLES. BUT AS THE RIDGE STARTS TO WEAKEN/ERODE THE INVERSION CAP
IS TO SLOWLY LIFT ABOVE 700 HPA. THIS WILL ALLOW FOR DEEPER LAYER
INSTABILITY TO ESTABLISH AND GRADUAL INTENSIFICATION OF THE SEA
BREEZE CONVERGENCE CYCLE ON FRIDAY TO SATURDAY.

A TUTT LOW TO THE SOUTH OF THIS RIDGE CENTERS OVER THE NORTHWEST
CARIBBEAN/ NORTHERN CENTRAL AMERICA. THE RIDGE TO THE NORTH IS TO
STEER THIS LOW WEST ACROSS BELIZE INTO THE YUCATAN LATER ON
FRIDAY. BUT AS THE RIDGE WEAKENS THE WANING TUTT IS TO STALL OVER
THE YUCATAN. EARLY IN THE CYCLE...AS IT MEANDERS OVER THE WESTERN
CARIBBEAN...THE LOW IS TO ENHANCE CONVECTION ACROSS THE CAYMAN
ISLES TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM.
OVER CUBA MOST ACTIVE IS EXPECTED ON THE WESTERN HALF OF THE
ISLAND WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM.
THIS IS TO ALSO ENHANCE CONVECTION ACROSS NORTHERN CENTRAL
AMERICA...WITH MOST ACTIVE OVER EL SALVADOR-SOUTHERN HONDURAS AND
SOUTHERN GUATEMALA TO SUSTAIN RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 25-50MM. ACROSS NORTHEAST NICARAGUA-NORTHERN HONDURAS TO
BELIZE/NORTHERN GUATEMALA EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM. AS THE LOW MEANDERS
WEST...FOCUS OF THE CONVECTION WILL SHIFT TO
BELIZE-GUATEMALA-YUCATAN AND NORTHWEST HONDURAS WITH RAINFALL
AMOUNTS OF 10-15XMM/DAY AND MAXIMA OF 20-30MM.

ANOTHER TUTT LOW TO THE EAST CENTERS NEAR THE VIRGIN ISLES. THIS
LOW EXTENDS A SHORT WAVE TROUGH SOUTH TO CENTRAL/EASTERN
VENEZUELA. BUILDING CELL OF THE SUBEQUATORIAL RIDGE OVER THE
TROPICAL ATLANTIC IS TO DISPLACE THIS LOW/TROUGH TO THE
WEST-NORTHWEST EARLY ON SATURDAY. EARLY TODAY THE MEANDERING LOW
WILL ENHANCE DIURNAL CONVECTION ACROSS THE NORTHERN LEEWARD ISLES
TO RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM. ON FRIDAY TO SATURDAY THIS IS TO BUILD WEST ACROSS THE
VIRGIN ISLES TO EASTERN PUERTO RICO WHERE WE EXPECT RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. OTHER ENHANCEMENT TO
THE SOUTH IS EXPECTED IN INTERACTION WITH THE NEAR EQUATORIAL
TROUGH OVER VENEZUELA. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM THROUGH EARLY SATURDAY.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
46W     48W    51W    54W    58W    61W    64W    66W        TW
77W     79W    81W    83W    86W    89W    91W    93W        TW
86W     88W    91W    94W    96W    98W   100W   102W        TW
100W   101W   102W   103W   104W   106W   108W   110W        TW

TROPICAL WAVE ALONG 46W IS FORECAST TO MOVE TO NORTHERN FRENCH
GUIANA EARLY ON FRIDAY MORNING...WHERE IT IS TO FAVOR COASTAL
CONVECTION WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM. OVER NORTHERN SURINAME-GUYANA THIS IS TO ALSO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM DURING THE DAY ON FRIDAY
TO SATURDAY MORNING. ACROSS THE ISLAND CHAIN IT IS TO THEN TRIGGER
TRACE RAINFALL AMOUNTS.

TROPICAL WAVE ALONG 77W IS TO FAVOR ISOLATED TO SCATTERED
CONVECTION ACROSS JAMAICA WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM. MOST ACTIVE IS EXPECTED TO THE SOUTH OVER SOUTHERN
CENTRAL AMERICA AND WESTERN COLOMBIA WHERE IT IS TO FAVOR RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM. OVER COSTA
RICA-NICARAGUA THIS IS TO THEN SUSTAIN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM ON FRIDAY...WHILE OVER EL
SALVADOR/HONDURAS EXPECT RAINFALL ACCUMULATION OF 15-20MM/DAY AND
MAXIMA OF 25-50MM ON SATURDAY.

TROPICAL WAVE ALONG 88W...IN INTERACTION WITH THE WESTERN
CARIBBEAN TUTT...WILL SUSTAIN SCATTERED CONVECTION ACROSS
HONDURAS/EL SALVADOR TO GUATEMALA...WITH RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM. OVER THE SOUTHERN STATES OF
MEXICO THE WAVE IS TO THEN TRIGGER RAINFALL AMOUNTS OF 15-20MM/DAY
AND MAXIMA OF 25-50MM.

TROPICAL WAVE ALONG 100W IS TO INTERACT WITH MEANDERING MID/UPPER
LEVEL TROUGH OVER THE WESTERN GULF-CENTRAL MEXICO. AS THE WAVE
MOVES ACROSS CENTRAL-SOUTHWEST MEXICO IT IS TO FAVOR SCATTERED
DEEP CONVECTION WITH RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
35-70MM.

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

$$





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