Prognostic Meteorological Discussion
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FXCA20 KWBC 021610
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1209 PM EDT THU JUL 02 2015

LAST NO AMENDS...NEXT BULLETIN ON MONDAY JULY 06.

DISCUSSION FROM JUL 02/12 UTC: SEASONAL ACTIVE PATTERN IS WELL
ESTABLISHED ALONG THE SIERRA MADRE OCCIDENTAL/WESTERN MEXICO WHERE
MODELS ARE SHOWING LARGEST CONVECTIVE INSTABILITY TO LINGER
THROUGH THE CYCLE...WITH GDI VALUES EXCEEDING 45/50 FROM
GUERRERO/MICHOACAN NORTHWEST INTO THE US BORDER ON A DAILY BASIS.
AT UPPER LEVELS A RIDGE HAS ESTABLISHED OVER NEW MEXICO WHILE
COVERING TEXAS AND NORTHERN MEXICO...SUSTAINED BY THE LATENT HEAT
RELEASE FROM ACTIVE DEEP CONVECTION. RIDGE IS FORECAST TO CONTINUE
DOMINATING THIS REGIONS THROUGH THE CYCLE TO CENTER OVER NEW
MEXICO/CHIHUAHUA AND SPREAD INTO CENTRAL MEXICO BY 72-96
HRS...VENTILATING DIURNAL CONVECTION ESPECIALLY ALONG ITS
PERIPHERY. A WEAK TUTT TO THE SOUTHEAST OF THE RIDGE IS
RETROGRESSING ACROSS SOUTHWESTERN MEXICO...AND IS FORECAST TO
INTENSIFY DEVELOPING A CLOSED CIRCULATION LATE ON THURSDAY WHILE
MOVING TO THE SOUTH-SOUTHWEST INTO THE TROPICAL EASTERN PACIFIC.
THIS SYSTEM WILL ENHANCE INSTABILITY AND VENTILATION IN
SOUTHWESTERN MEXICO TO SUSTAIN AN ACTIVE PATTERN OF DIURNAL
CONVECTION.

THROUGH EARLY FRIDAY EXPECTING STRONGEST ACTIVITY TO CLUSTER ALONG
SOUTHWESTERN MEXICO WITH ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA
OF 25-50MM. ACROSS NORTHWESTERN MEXICO EXPECTING MAXIMA OF
20-30MM/DAY. BY FRIDAY INTO EARLY SATURDAY LARGEST ACCUMULATIONS
ARE TO SPREAD INTO CENTRAL MEXICO WITH SIMILAR AMOUNTS. A SURGE IN
ACTIVITY IS EXPECTED ALONG VERACRUZ WITH MAXIMA INCREASING TO
20-40MM/DAY. BY SATURDAY INTO EARLY SUNDAY EXPECTING TWO REGIONS
WITH ENHANCED ACTIVITY...CENTRAL/SOUTHERN MEXICO WHERE EXPECTING
MAXIMA OF 25-50MM/DAY IN DIURNAL CONVECTION...AND SONORA/WESTERN
CHIHUAHUA WHERE EXPECTING MAXIMA OF 20-40MM/DAY WITH THE RISK FOR
NOCTURNAL MCS FORMATION. ALSO EXPECTING MAXIMA OF 20-40MM/DAY
ALONG THE SIERRA MADRE ORIENTAL. BY SUNDAY INTO MONDAY EXPECTING
ACTIVE DIURNAL CONVECTION ACTIVATING ACROSS THE ENTIRE SIERRA
MADRE OCCIDENTAL ONCE AGAIN...CONTINUING AS WELL OVER
CENTRAL/SOUTHERN MEXICO.

TO THE EAST A BROAD TUTT CENTERS OVER WESTERN CUBA WHILE
DOMINATING MOST OF THE EASTERN GULF OF MEXICO AND NORTHWESTERN
CARIBBEAN. TUTT IS FORECAST TO DRIFT SLOWLY NORTHWARD INTO THE
EASTERN GULF OF MEXICO TO PERSIST IN THIS REGION INTO EARLY NEXT
WEEK. TUTT WILL VENTILATE DIURNAL CONVECTION OVER CUBA/SOUTHERN
YUCATAN/SOUTHEASTERN MEXICO THROUGH THE WEEKEND...INITIALLY IN
ASSOCIATION WITH THE NORTHERN TIER OF A WEAK TROPICAL WAVE AND
THEN IN ASSOCIATION WITH TRADE WIND CONVERGENCE AS 20-30KT TRADES
INTERACT WITH THE NORTHEASTERN SLOPES OF SOUTHERN
MEXICO/GUATEMALA. ACROSS BELIZE/NORTHERN GUATEMALA EXPECTING
MAXIMA IN THE ORDER OF 15-20MM/DAY THROUGH THE CYCLE. ACROSS CUBA
EXPECTING MAXIMA OF 15-20MM/DAY THROUGH EARLY FRIDAY DECREASING TO
MAXIMA OF 15MM AFTER.

CENTRAL AMERICA WILL EXPERIENCE A SEASONALLY QUIET PATTERN OVER
AND NORTH OF NICARAGUA UNDER THE INFLUENCE OF PERSISTENT BRISK
TRADES...WHICH ARE REACHING SPEEDS OF 30-40KT OVER THE WESTERN
CARIBBEAN. THIS WILL CONTINUE SUSTAINING PATTERN OF ISOLATED TO
SCATTERED DIURNAL CONVECTION EAST OF THE CONTINENTAL DIVIDE AND
DRY CONDITIONS ACROSS THE PACIFIC BASIN. TO THE SOUTH OF NICARAGUA
HOWEVER EXPECTING A SIGNIFICANT ACTIVATION DURING SATURDAY AND
ESPECIALLY SUNDAY IN ASSOCIATION WITH AN INTENSIFICATION OF THE
PANAMANIAN LOW AS TROPICAL WAVE ARRIVES FROM COLOMBIA (SEE BELOW).
EXPECTING ACCUMULATIONS TO INCREASE TO MAXIMA OF 15-30MM/DAY
ACROSS COSTA RICA/WESTERN PANAMA...WITH A FURTHER INCREASE AFTER.

A WELL DEFINED TUTT CENTERS TO THE NORTHEAST OF THE TURKS AND
CAICOS. THIS SYSTEM IS HAVING LIMITED EFFECTS ON CONVECTION AS THE
STRONG RIDGE PATTERN DOMINATES THE MID-LEVELS OVER THE
NORTHEASTERN CARIBBEAN. TUTT IS FORECAST TO MEANDER NORTH INTO
25N-27N AND 70W BY THE END OF THE WEEKEND. AS IT DOES SO...IT WILL
STILL SUSTAIN A SOUTHWESTERLY JET IN ITS EASTERN PERIPHERY. UNDER
THIS PATTERN EXPECTING LOCAL ENHANCEMENT OF CONVECTION OVER
HISPANIOLA ESPECIALLY ON SATURDAY. AFTER THIS PERIOD A DRY AND
STABLE AIR MASS ARRIVES FROM THE EAST TO PRODUCE A DECREASE OF
ACTIVITY INTO SUNDAY. EXPECTING MAXIMA ON SATURDAY INTO EARLY
SUNDAY TO PEAK AT 15-20MM/DAY.

DRY PATTERN IS TO CONTINUE DURING THE NEXT SEVERAL DAYS OVER THE
EASTERN CARIBBEAN. CONVECTION WILL BE MOSTLY ISOLATED AND CONFINED
TO WAVES IN THE TRADES (SEE BELOW). A SLIGHT ENHANCEMENT OF
CONVECTIVE INSTABILITY IS EXPECTED ON FRIDAY IN ASSOCIATION WITH
TROPICAL WAVE. THIS WILL LEAD TO AN ENHANCEMENT IN SHOWER ACTIVITY
THAT IS TO RAPIDLY WANE DURING FRIDAY EVENING. THIS WILL LEAD TO
MAXIMA IN THE ORDER OF 10MM/DAY BETWEEN PUERTO RICO/LEEWARD
ISLANDS SOUTH INTO ST. LUCIA...AND MAXIMA OF 15MM/DAY TO THE
SOUTH. THE NEXT ROUND IF ACTIVITY IS EXPECTED ON SUNDAY WITH NEXT
TROPICAL WAVE. THIS TIME...DEEP-LAYER CONVECTIVE INSTABILITY AND
PRECIPITABLE WATER WILL SPREAD NORTH INTO
GRENADA/GRENADINES...THUS EXPECTING THUNDERSTORMS AND MODERATE
RAINFALL AMOUNTS BETWEEN THESE LOCATIONS AND NORTHEASTERN SOUTH
AMERICA. EXPECTING MAXIMA OF 15-25MM/DAY SOUTH OF THE GRENADINES
INTO TRINIDAD AND TOBAGO/NORTHEASTERN SOUTH AMERICA. A TUTT WILL
BE DRIFTING NORTHWESTWARD JUST TO THE EAST OF THE LESSER ANTILLES
INTO EARLY NEXT WEEK. THIS WILL UNDULATE A WAVE ALONG THE ITCZ
THAT WILL LEAD TO A TRANSIENT WETTER PATTERN ACROSS THE EASTERN
CARIBBEAN DURING EARLY NEXT WEEK...LIKELY ON THE MONDAY-TUESDAY
TIMEFRAME.

ACROSS NORTHERN SOUTH AMERICA CONVECTION WILL ORGANIZE ALONG THE
ITCZ/NET ESPECIALLY ACROSS CENTRAL VENEZUELA...AND WAVES IN THE
TRADES. A WAVE IS ENTERING GUYANA ON THURSDAY BUT PRECIPITABLE
WATER IS LIMITED AHEAD OF THE WAVE AXIS WHICH WILL LEAD TO
ISOLATED ACTIVITY (SEE BELOW FOR ACCUMULATIONS).

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
34W      39W    43W    48W    53W    57W    61W    66W       TW
53W      57W    61W    64W    68W    72W    76W    80W       TW
79W      DISSIPATES                                          TUTT
INDUCED
89W      91W    94W    97W    99W    102W   105W   108W      TW

TROPICAL WAVE ALONG 34W REACHES FRENCH GUIANA ON SATURDAY MORNING.
THIS WAVE IS ARRIVING WITH HIGHER PRECIPITABLE WATER VALUES THAN
THE PREVIOUS WAVES...AND THUS WILL ENHANCE ACTIVITY ESPECIALLY
ALONG THE ITCZ IN NORTHERN GUYANA/NORTHEASTERN VENEZUELA/TRINIDAD
AND TOBAGO DURING SATURDAY INTO SUNDAY. LARGEST AMOUNTS ARE
EXPECTED ACROSS NORTHERN GUYANA WITH MAXIMA OF 20-35MM/DAY FROM
SATURDAY INTO EARLY SUNDAY.

A TROPICAL WAVE ALONG 53W IS ARRIVING WITH LITTLE PRECIPITABLE
WATER INTO THE BASIN. THE WAVE WILL ENHANCE SHALLOW CONVECTION
ACROSS THE LESSER ANTILLES LATE ON THURSDAY AND DURING FRIDAY TO
PRODUCE SCATTERED ACCUMULATIONS BELOW 10-15MM/DAY. HIGHER AMOUNTS
ARE EXPECTED IN CENTRAL VENEZUELA DURING FRIDAY WITH MAXIMA OF
15-25MM/DAY...AND NORTHERN COLOMBIA/WESTERN VENEZUELA DURING
SATURDAY WITH MAXIMA OF 15-20MM/DAY...TO THEN ENHANCE ACTIVITY
OVER PANAMA AND COSTA RICA ON SUNDAY. ACROSS NORTHWESTERN
COLOMBIA...EXPECTING ACTIVITY PEAKING ON SATURDAY INTO SUNDAY WITH
MAXIMA OF 20-40MM/DAY.

WANING TUTT-INDUCED WAVE EXTENDS AT 79W AND WILL RAPIDLY LOOSE
DEFINITION.

TROPICAL WAVE ALONG 89W WILL ENHANCE ACCUMULATIONS IN NORTHERN
GUATEMALA/EXTREME SOUTHEASTERN MEXICO THROUGH EARLY
FRIDAY...SOUTHWESTERN AND CENTRAL MEXICO DURING FRIDAY INTO EARLY
SATURDAY TO THEN EXIT INTO THE PACIFIC WITH LITTLE EFFECTS ON THE
CONTINENT.

SALMON...MS (ANTIGUA AND BARBUDA)
SAMUEL...MDS (SURINAME)
GALVEZ...WPC (USA)
$$




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