Prognostic Meteorological Discussion
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FXCA20 KWBC 161832
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
232 PM EDT WED AUG 16 2017

TROPICAL DISCUSSION FROM AUG 16/12 UTC: A TUTT OVER THE WESTERN
GULF OF MEXICO SPLITS THE SUBTROPICAL RIDGE IN TWO CELLS...ONE
OVER MEXICO/SOUTHWEST USA AND THE OTHER OVER THE SOUTHEAST
USA/EASTERN GULF. THE ONE TO THE WEST IS TO ANCHOR ON A CLOSED
HIGH OVER THE STATE OF CHIHUAHUA...WHILE THE ONE TO THE EAST IS TO
INITIALLY CENTER OVER NORTHERN FLORIDA. UNDER INFLUENCE OF THIS
RIDGES THE TUTT IS TO MEANDER INLAND ACROSS NORTHEAST MEXICO LATER
ON THURSDAY-FRIDAY. BUT AS IT IS TO REMAIN CUT OFF FROM THE
FLOW...THE TUTT IS EXPECTED TO WEAKEN/GRADUALLY FILL AS IT MOVES
ACROSS NORTHERN MEXICO DURING THE WEEKEND. MEANWHILE...OVER THE
NEXT DAY OR SO... THE TUTT IS TO ENHANCE DIURNAL CONVECTION ACROSS
THE CENTRAL-NORTHEAST STATES OF MEXICO...TO FAVOR RAINFALL AMOUNTS
OF 15-20MM/DAY AND MAXIMA OF 25-50MM. ON THURSDAY-FRIDAY THIS
DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-25MM WHILE BUILDING
NORTH ACROSS VERACRUZ TO TAMAULIPAS/COAHUILA IN NORTHEAST MEXICO.
ON THE SOUTHWEST STATES OF MEXICO THIS IS TO FAVOR RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THE RIDGE ALOFT IS
TO VENT DIURNAL CONVECTION ALONG THE SIERRA MADRE OCCIDENTAL IN
WESTERN MEXICO...TO FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 25-50MM/DAY. ON FRIDAY THIS DECREASES TO 10-15MM/DAY AND
MAXIMA OF 20-40MM.

THE UPPER LEVEL RIDGE OVER THE SOUTHEAST USA BRANCHES ACROSS CUBA
TO CENTRAL AMERICA. THIS IS STEERING A WANING TUTT ACROSS
NICARAGUA TO HONDURAS...WITH AXIS TO MOVE OVER GUATEMALA LATER ON
THURSDAY. SOME ENHANCEMENT OF DIURNAL CONVECTION IS POSSIBLE OVER
NORTHERN CENTRAL AMERICA...WHERE WE EXPECT RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM OVER THE NEXT FEW DAYS. THROUGH
THURSDAY EVENING CONVECTION IS TO EXPAND ACROSS GUATEMALA/BELIZE
TO THE SOUTHERN STATES OF MEXICO WHERE IT IS TO FAVOR SIMILAR
RAINFALL AMOUNTS.

ANOTHER TUTT LIES TO THE EAST OF THE UPPER LEVEL RIDGE...WITH AXIS
SOUTH FROM A CLOSED LOW NORTH OF THE DOMINICAN REPUBLIC TO THE
CENTRAL CARIBBEAN. BUILDING CELL OF THE SUBTROPICAL RIDGE IS TO
DISPLACE THIS TROUGH TO THE WEST...WITH LOW MOVING OVER THE
TURKS/SOUTHEAST BAHAMAS LATER TODAY. ON THURSDAY IT MEANDER ACROSS
EASTERN CUBA...AND TO WESTERN/CENTRAL PORTIONS OF THE ISLAND LATER
ON FRIDAY. ON ITS WAKE...THE SUBTROPICAL RIDGE IS TO THEN BUILD
ACROSS THE NORTHEAST CARIBBEAN ISLES. THIS IS TO STRENGTHEN THE
TRADE WINDS CAP...FAVORING RAPID EROSION OF AVAILABLE MOISTURE.
MEANWHILE...ENVIRONMENTAL CONDITIONS ARE TO REMAIN FAVORABLE FOR
GENERATION OF MESO SCALE CONVECTIVE SYSTEMS...TO INITIALLY AFFECT
THE LEEWARD-VIRGIN ISLES AND PUERTO RICO. THIS IS TO FAVOR
RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 40-80MM. ON THURSDAY
THE CONVECTION SPREADS ACROSS THE DOMINICAN REPUBLIC AND PORTIONS
OF HAITI WHERE IT IS TO SUSTAIN SIMILAR RAINFALL AMOUNT. ACROSS
EASTERN CUBA/JAMAICA INITIALLY EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM. THIS INCREASES TO 10-15MM/DAY AND
MAXIMA OF 20-40MM ON FRIDAY-SATURDAY. ACROSS THE BAHAMAS THIS IS
TO ALSO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-40MM ON FRIDAY TO SATURDAY...WHILE OVER THE CAYMAN ISLES
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM.

ALONG THE BASE OF THE TUTT...IN INTERACTION WITH THE ITCZ/NEAR
EQUATORIAL TROUGH...EXPECTING MODERATE CONVECTION TO AFFECT
CENTRAL/EASTERN PANAMA-NORTHERN COLOMBIA THROUGH THURSDAY
MORNING...WITH RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM. AS THE UPPER TROUGH MEANDERS WEST THIS DECREASES TO
05-10MM/DAY AND MAXIMA OF 15-30MM ON FRIDAY. ACROSS EASTERN
COLOMBIA-WESTERN/CENTRAL VENEZUELA...MEANWHILE...EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM...WHILE OVER
NORTHEAST VENEZUELA-GUIANA EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL   24    36    48    60    72    84    96  TYPE
36W      39W   42W   46W   50W   54W   58W   62W  TW
48W      50W   53W   56W   59W   63W   66W   69W  TW
60W      64W   68W   71W   75W   79W   82W   84W TUTT INDCD
75W      78W   81W   84W   87W   90W   DISSIPATES TW
83W      86W   89W   DISSIPATES       EW
101W    104W  107W  110W  112W  114W  116W  118W  TW

A TROPICAL WAVE ALONG 36W AND SOUTH OF 19N REACHES THE LESSER
ANTILLES LATER ON SATURDAY. THIS IS TO PHASE WITH A TUTT ALOFT TO
FAVOR ORGANIZED CONVECTION OVER THE FRENCH-LEEWARD ISLES DURING
THE WEEKEND.

A TROPICAL WAVE ALONG 48W AND SOUTH OF 19N MOVES NORTH OF THE
GUIANAS ON THURSDAY...TO TRIGGER SCATTERED CONVECTION ACROSS
NORTHERN GUYANA/NORTHEAST VENEZUELA WITH ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-20MM. STEERED BY BROAD CELL OF THE
SUBTROPICAL RIDGE TO THE NORTH THE WAVE IS TO THEN FOCUS ITS
ENERGY/MOISTURE ACROSS THE WINDWARD/FRENCH ISLES EARLY ON
FRIDAY...TO TRIGGER RAINFALL AMOUNTS OF 20-40MM/DAY AND MAXIMA OF
75-125MM. THIS IS TO THEN INDUCE THE NORTHWARD MODULATION OF THE
ITCZ OVER THE WINDWARD ISLES...WHERE IT IS TO FAVOR ADDITIONAL
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM.

RETROGRESSING TUTT NORTH OF THE DOMINICAN REPUBLIC SUSTAINS AN
INDUCED/INVERTED TROUGH IN THE EASTERLY TRADES...WITH AXIS NORTH
ALONG 60W TO 23N. THE WAVE IS ENHANCING MOISTURE
TRANSPORT/CONVERGENCE ACROSS THE EASTERN CARIBBEAN ISLES. MOST
ACTIVE CONVECTION IS EXPECTED OVER THE LEEWARD-VIRGIN ISLES-PUERTO
RICO...WHERE CONDITIONS ARE FAVORABLE FOR AN MCS TO FORM...TO
SUSTAIN RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 40-80MM.
LOCALLY HIGHER AMOUNTS ARE HIGHLY PROBABLE. THIS SPREADS ACROSS
HISPANIOLA ON THURSDAY WHERE IT IS TO FAVOR SIMILAR RAINFALL
AMOUNTS. ACROSS CUBA-JAMAICA AND THE BAHAMAS THIS IS TO THEN
TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM ON
FRIDAY-SATURDAY.

A TROPICAL WAVE ALONG 75W AND TO THE SOUTH OF 23N IS TO TRIGGER
SCATTERED CONVECTION ACROSS NORTHERN COLOMBIA-PANAMA EARLY IN THE
CYCLE...TO FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM. ACROSS JAMAICA AND CUBA THIS IS TO FAVOR RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15-25MM. ON THURSDAY IT WILL ENHANCE
ITCZ RELATED CONVECTION OVER COSTA RICA-SOUTHERN NICARAGUA TO
FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-40MM...WHILE OVER NORTHEAST NICARAGUA/VENEZUELA EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. OVER
NICARAGUA-GUATEMALA THIS IS TO THEN SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM ON FRIDAY-SATURDAY.

AN EASTERLY WAVE ALONG 83W AND SOUTH OF 18N IS FORECAST TO
DISSIPATE ON THURSDAY. MEANWHILE...AS IT PULLS ACROSS NICARAGUA TO
HONDURAS THIS IS TO TRIGGER RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM.

A TROPICAL WAVE ALONG 101W AND SOUTH OF 20N...IN INTERACTION WITH
THE RETROGRESSING TUTT OVER THE GULF...WILL SUSTAIN SCATTERED
CONVECTION ACROSS SOUTHWESTERN MEXICO TO TRIGGER RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-30MM.

GUY...NMS (BELIZE)
DAVISON/GALVEZ...WPC (USA)

$$





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