Prognostic Meteorological Discussion
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FXCA20 KWBC 241826
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
226 PM EDT MON JUL 24 2017

AT 15 UTC HURRICANE HILLARY CENTERED NEAR 14.1N 104.2W...WITH
MINIMAL CENTRAL PRESSURE OF 989 HPA AND MAXIMUM SUSTAINED WINDS OF
70KT. THE HURRICANE IS MOVING WEST-NORTHWEST AT 07KT. SEE NHC
DISCUSSION FOR OFFICIAL FORECAST.

TROPICAL DISCUSSION FROM JUL 24/12 UTC: A 250 HPA HIGH OVER NEW
MEXICO ANCHORS A RIDGE OVER THE WESTERN USA-NORTHERN STATES OF
MEXICO. A BROAD TROUGH LIES TO THE EAST...WITH AXIS ENVELOPING THE
CENTRAL-EASTERN USA-NORTHERN GULF OF MEXICO. THE UPPER LEVEL
TROUGH IS INTERACTING WITH A TUTT TO THE SOUTH. THE TUTT EXTENDS
FROM A CLOSED LOW OVER THE EASTERN GULF TO CENTRAL MEXICO. THE
TUTT LOW IS TO REMAIN CUT OFF FROM THE FLOW...WITH AXIS TO MEANDER
INLAND ACROSS TAMAULIPAS/NORTHERN VERACRUZ LATER ON WEDNESDAY. THE
TUTT HAS A MID LEVEL REFLECTION...WITH AN INDUCED/INVERTED TROUGH
TO MEANDER INLAND INTO NORTHEAST MEXICO LATER ON TUESDAY/EARLY
WEDNESDAY MORNING. AS IT MEANDERS OVER THE GULF...THE UPPER LEVEL
TROUGH IS TO VENT DEEP CONVECTION ACROSS VERACRUZ/CENTRAL
MEXICO...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-35MM. THROUGH TUESDAY EVENING THIS IS TO BUILD NORTH
ACROSS TAMAULIPAS/NORTHEAST MEXICO WHERE IT IS TO FAVOR SIMILAR
RAINFALL AMOUNTS.

OTHER CONVECTION IS TO AFFECT THE SOUTHWEST STATES OF MEXICO UNDER
INFLUENCE OF HURRICANE HILLARY TO THE SOUTH. OUTER BAND CONVECTION
FROM THE STORM IS TO ENHANCE LATE AFTERNOON CONVECTION ACROSS
SOUTHERN SINALOA-NAYARIT/COLIMA-GUERRERO...TO FAVOR RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON TUESDAY THIS
INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-45MM WHILE BUILDING
NORTH ACROSS SINALOA. ON WEDNESDAY THIS INCREASES TO 15-20MM/DAY
AND MAXIMA OF 25-50MM. OTHER CONVECTION IS TO CLUSTER ACROSS
SONORA-WESTERN CHIHUAHUA...TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM.

A BROAD CELL OF THE SUBTROPICAL RIDGE LIES TO THE EAST...WITH AXIS
AT 500/250 HPA DOMINATING THE FLOW OVER THE WESTERN ATLANTIC-NORTH
OF THE ISLANDS WHILE CENTERING ON A CLOSED HIGH TO THE
EAST-SOUTHEAST OF BERMUDA. AS THE RIDGE HOLDS TO THE NORTH...IT IS
TO STEER A FEW TUTTS ACROSS THE CENTRAL ATLANTIC AND THE
CARIBBEAN. ONE LIES OVER THE CENTRAL CARIBBEAN...AND UNDER
INFLUENCE OF THE RIDGE IT IS TO LIFT TO THE NORTHWEST CARIBBEAN
LATER ON WEDNESDAY. THIS IS TO THEN INTERACT WITH MEANDERING
TROUGH OVER THE BAHAMAS/CUBA. THE TROUGH ALOFT IS TO ENHANCE
CONVECTIVE INSTABILITY ACROSS CUBA...TO VENT AFTERNOON CONVECTION
ACROSS THE ISLAND. MOST ACTIVE IS EXPECTED ON THE WESTERN
HALF...WHERE THE DAILY MAXIMA IS TO PEAK AT 15-20MM EARLY IN THE
CYCLE...AND THEN SETTLE AT 10-15MM/DAY...WHILE TO THE EAST
EXPECTING MAXIMA OF 10-15MM/DAY. EARLY IN THE CYCLE...THE TUTT IS
TO ALSO INTERACT WITH THE NEAR EQUATORIAL TROUGH OVER
COLOMBIA...TO INITIALLY FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM. ON TUESDAY-WEDNESDAY THIS INCREASES TO
10-15MM/DAY AND MAXIMA OF 20-30MM. HIGHER AMOUNTS ARE EXPECTED
OVER CENTRAL VENEZUELA...WHERE THE DAILY MAXIMA IS TO PEAK AT
20-45MM.

ANOTHER TUTT TO THE EAST EXTENDS FROM A CLOSED LOW AT 23N 49W TO
THE EASTERN CARIBBEAN ISLES. THROUGH WEDNESDAY EVENING...UNDER
INFLUENCE OF THE RIDGE TO THE WEST AND NORTH...THE TUTT WILL
RETROGRESS TO 60W. THIS FEATURE HAS A FAIRLY STRONG MID LEVEL
REFLECTION...WITH MODELS SHOWING A CLOSED LOW MEANDERING TO THE
NORTHEAST OF THE ISLAND CHAIN ON TUESDAY-WEDNESDAY. THE DEEP MID
LEVEL TROUGH PATTERN IS TO ALSO INDUCED LOW/MID LEVEL
PERTURBATIONS IN THE EASTERLY TRADES. SEE BELOW FOR DETAILS.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL   24     36     48     60     72     84     96     TYPE
40W      44W    48W    51W    55W    58W    61W    64W  TUTT INDCD
51W      53W    56W    58W    61W    64W    67W    70W  TUTT INDCD
60W      63W    67W    71W    74W    78W    81W    83W  TUTT INDCD
72W      77W    81W    84W    88W    91W    95W    98W     TW
87W      90W    93W    96W    99W   102W   105W   108W     EW

A TUTT INDUCED TROUGH ALONG 40W NEARS THE LEEWARD ISLES EARLY ON
THURSDAY MORNING...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM.

A TUTT INDUCED TROUGH ALONG 51W REACHES THE LEEWARD/FRENCH ISLES
EARLY ON WEDNESDAY MORNING. AS IT ENTERS THE ISLANDS THIS IS TO
SUSTAIN RAINFALL AMOUNT OF 05-10MM/DAY AND MAXIMA OF 15MM. ACROSS
THE NORTHERN LEEWARD-VIRGIN ISLES-PUERTO RICO THIS IS TO THEN
FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM
THROUGH WEDNESDAY MORNING. ACROSS HISPANIOLA THIS IS TO THEN FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM ON WEDNESDAY
TO THURSDAY.

A TUTT INDUCED PERTURBATION...ANALYZED AT 700 HPA...SUSTAINS THE
NORTHWARD MODULATION OF THE ITCZ ACROSS BARBADOS TO THE WINDWARD
ISLANDS...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIM OF 20-30MM. ACROSS THE LEEWARD ISLES THIS IS TO ONLY FAVOR
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. OVER THE
VIRGIN ISLES-PUERTO RICO THIS IS TO ONLY FAVOR LIGHT CONVECTION
EARLY ON TUESDAY. OVER HISPANIOLA IT IS TO BECOME SOMEWHAT MORE
ACTIVE LATER ON TUESDAY...TO TRIGGER RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM...WHILE OVER THE TURKS/SOUTHEAST
BAHAMAS IT IS TO ONLY TRIGGER WIDELY ISOLATED CONVECTION. OVER
EASTERN CUBA THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-20MM.

TROPICAL WAVE ALONG 72W IS TO SUSTAIN SCATTERED CONVECTION ACROSS
NORTHERN COLOMBIA-EASTERN PANAMA AS IT INTERACTS WITH THE
ITCZ/NEAR EQUATORIAL TROUGH...TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM. OVER EASTERN CUBA THIS IS TO
TRIGGER RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM...WHILE
OVER JAMAICA MOST ACTIVE IS EXPECTED NEAR MONTEGO BAY/NORTHWEST
PORTIONS OF THE ISLAND. OVER WESTERN PANAMA-COSTA RICA THIS IS TO
SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY ND MAXIMA OF
20-30MM...WHILE OVER NORTHEAST NICARAGUA/HONDURAS IT WILL FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. OVER WESTERN
CUBA THIS WILL SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15MM. ON WEDNESDAY...ACROSS BELIZE-GUATEMALA-CHIAPAS IN
SOUTHERN MEXICO THIS IS TO THEN TRIGGER RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM.

AN EASTERLY WAVE IS INITIALIZED ALONG 87W. THIS MOVES ACROSS
GUATEMALA TO SOUTHERN MEXICO EARLY IN THE CYCLE...TO TRIGGER
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. AS IT
SPREADS ACROSS VERACRUZ ON TUESDAY IT IS TO TRIGGER RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM...WHILE OVER OAXACA
TO GUERRERO THE MAXIMA WILL PEAK AT 20-45MM. ON WEDNESDAY ACTIVITY
SPREADS ACROSS SOUTHWEST STATES OF MEXICO WHERE IT WILL SUSTAIN
MAXIMA OF 25-50MM.

GAJADHAR...SLMS (SAINT LUCIA)
DAVISON...WPC (USA)
$$




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