TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
225 PM EDT THU JUL 02 2009
 
LAST NO AMENDS... NEXT BULLETIN JUL 06.

DISCUSSION FROM JUL 02/0000 UTC. NORTH OVER THE DOMAIN...A 250 HPA
RIDGE EXTENDS FROM NORTHERN MEXICO INTO THE WESTERN USA...WHILE A
TROUGH LIES TO THE EAST ACROSS THE EASTERN USA TO THE NORTHERN
GULF. DOWNSTREAM FROM THIS TROUGH...A RIDGE REMAINS OVER THE
WESTERN ATLANTIC AND NORTH OF THE GREATER ANTILLES. THE MODELS
FORECAST THE CONTINENTAL RIDGE TO BUILD/INTENSIFY DURING THE
CYCLE...TO EXPAND ACROSS THE MISSISSIPPI VALLEY TO THE EASTERN USA
BY 30-36 HRS. THE ATLANTIC RIDGE...MEANWHILE...WILL HOLD ITS
GROUND. AS A RESULT...THE TROUGH OVER THE EASTERN USA GRADUALLY
DAMPENS AS ENERGY SHEARS NORTHWARD AND SOUTHWESTWARD...WITH THE
TROUGH TO BECOME NARROW/ELONGATED AS IT STRETCHES ALONG THE
WESTERN ATLANTIC-NORTHERN FLORIDA-NORTHERN GULF TO NORTHEAST
MEXICO BY 48 HRS. THROUGH 72 HRS THE TROUGH WILL MEANDER EAST AND
SOUTH...TO EXTENDS ACROSS THE NORTHWEST BAHAMAS-SOUTHERN
FLORIDA-THE GULF TO NORTHEAST MEXICO. THE TROUGH/RIDGE PAIR ALOFT
IS VENTING DEEP CONVECTION ACROSS THE NORTHWEST BAHAMAS...A
PATTERN THAT PERSISTS THROUGH 72 HRS...AND IT IS TO MEANWHILE
ENHANCE DIURNAL CONVECTION WHILE FAVORING RAINFALL ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-25MM/DAY. MOST INTENSE...HOWEVER...IS
EXPECTED ON DAY 01 WITH MAXIMA OF 20-35MM.

THE INFLOW OF COLD/POLAR ENERGY ACROSS THE GULF WILL HELP SUSTAIN
A SERIES OF TUTTS OVER NORTHEAST MEXICO...THAT ARE TO EXTEND
ACROSS TAMAULIPAS/SAN LUIS POTOSI TO JALISCO/ CENTRAL MEXICO. THE
INFLOW OF COLD AIR ALOFT...IN COMBINATION WITH DIURNAL
HEATING...IS ENHANCING CONVECTIVE INSTABILITY ACROSS MEXICO. ON
THE NORTHERN STATES...WITH MOST INTENSE ON THE SIERRA MADRE...THE
RAINFALL AMOUNTS WILL RANGE BETWEEN 10-15MM/DAY AND THE MAXIMA
WILL PEAK AT 20-40MM/DAY. HIGHER AMOUNTS...HOWEVER...ARE EXPECTED
ACROSS VERACRUZ/TAMAULIPAS AND SAN LUIS POTOSI WHERE THE MAXIMA ON
DAY 01 PEAKS AT 30-60MM/DAY AS MOISTURE SURGES NORTH. ON THE
CENTRAL STATES OF MEXICO...FROM JALISCO/COLIMA TO OAXACA/MEXICO
DF...EXPECT RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 30-60MM.
ON THE SOUTHERN STATES OF MEXICO... THE MAXIMA WILL PEAK AT
35-70MM/DAY...WITH LOCALLY HIGHER AMOUNTS POSSIBLE OVER THE
MOUNTAINS ON DAY 01 TO PEAK AT 75-125MM. MOST INTENSE WILL
ASSOCIATE WITH TROPICAL WAVES.

UNDER INFLUENCE OF THE SUBTROPICAL RIDGE NORTH OF THE ISLANDS...A
TUTT LOW NEAR THE CAYMAN ISLANDS WILL RETROGRESS TO THE WESTERN
CARIBBEAN THROUGH 24 HRS...TO MEANDER ACROSS THE YUCATAN CHANNEL
TO THE GULF OF HONDURAS. THIS FEATURE IS CUT OFF FROM THE
FLOW...AND AS SUCH IT IS EXPECTED TO SLOWLY WEAKEN/DISSIPATE.
EARLY THIS PERIOD THIS FEATURE WILL ENHANCE CONVECTION ACROSS THE
CAYMAN ISLANDS...TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM. IT IS TO ALSO ENHANCE SEA BREEZE RELATED
CONVERGENCE ACROSS CENTRAL AND WESTERN CUBA TO RESULT IN RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 20-35MM/DAY. LOCALIZED MAXIMA
OF 25-50MM IS QUITE POSSIBLE. THE MOST INTENSE CONVECTION IS
EXPECTED OVER CENTRAL AMERICA...ALONG THE BASE OF THE TUTT...WHERE
IT IS INTERACTING WITH THE NEAR EQUATORIAL TROUGH/ITCZ. OVER COSTA
RICA AND PANAMA EXPECT ACCUMULATION OF 15-30MM/DAY AND MAXIMA OF
40-80MM ON DAY 01...WHILE ON DAYS 02-03 THE RAINFALL AMOUNTS WILL
RANGE BETWEEN 05-10MM/DAY AND MAXIMA OF 15-30MM. MAXIMA OF
30-60MM/DAY IS TO CONCENTRATE OVER EASTERN NICARAGUA/ NORTHEAST
HONDURAS THROUGH DAY 02...AND 20-40MM/DAY THEREAFTER. OVER
BELIZE/QUINTANA ROO IN THE YUCATAN AND PORTIONS OF GUATEMALA
EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM/DAY.

AT 250 HPA...A RIDGE REMAINS OVER THE WESTERN ATLANTIC AND NORTH
OF THE GREATER ANTILLES...CENTERING ON A MEANDERING HIGH AT 30N
60W THROUGH 36-42 HRS. BY 72 HRS THE HIGH WILL MOVE EAST TO 25N
53W. AT 500 HPA IT CENTERS ON A HIGH THAT MEANDERS NEAR 25N 65W
THROUGH 36-42 HRS...TO ALSO RELOCATE EAST TO 25N 58W BY 72 HRS.
THE MID LEVEL RIDGE PATTERN SUSTAINS A FAIRLY STRONG SUBSIDENCE
CAP OVER THE LEEWARD/ VIRGIN ISLANDS TO PUERTO RICO-DOMINICAN
REPUBLIC. THIS IS TO WANE THROUGH 60 HRS...WITH A CONVECTIVELY
UNSTABLE AIR MASS TO ESTABLISH BY 60-84 HRS. AT 850 HPA THE RIDGE
PATTERN DOMINATES FLOW BETWEEN 15N-35N...FAVORING A BRISK EASTERLY
FLOW ACROSS THE ISLAND CHAIN TO THE CENTRAL CARIBBEAN. THE
EASTERLIES ARE TO SURGE EARLY THIS PERIOD... AND THROUGH 36-48 HRS
THEY ARE TO RAPIDLY INTENSIFY. BOUNDARY LAYER WINDS WILL PEAK AT
25-40KT BY 54-60 HRS... WITH MOST INTENSE ALONG THE COAST OF
VENEZUELA/NORTHERN COLOMBIA TO THE ABC ISLANDS. 

FURTHERMORE...THE 250 HPA RIDGE WILL FAVOR FORMATION OF A TUTT
OVER THE EASTERN CARIBBEAN EARLY THIS CYCLE...WITH A LOW TO CUTOFF
NEAR 13N 63W BY 30-36 HRS. THIS LOW WILL RETROGRESS TO JUST NORTH
OF THE ABC ISLANDS/LA GUAJIRA PENINSULA BY 48-60 HRS...WHERE IT
WILL MEANDER THROUGH 72-84 HRS. AS THE TUTT INTERACTS WITH A
TROPICAL WAVE ENTERING THE ISLANDS BY MID CYCLE...MOISTURE IS TO
GRADUALLY SURGE ACROSS THE WINDWARD ISLES/NORTHERN VENEZUELA AND
THEN NORTHWARD TO PUERTO RICO/USVI-DOMINICAN REPUBLIC. POSITIVE
INTERACTION BETWEEN THESE FEATURES IS LIKELY TO FAVOR SQUALLY
WEATHER ACROSS THE ISLAND CHAIN BY 30-36 HRS...AND INTO THE
EASTERN CARIBBEAN THROUGH 48-72 HRS. OTHER ENHANCEMENT IS EXPECTED
ACROSS VENEZUELA ALONG THE NEAR EQUATORIAL TROUGH...WITH
POSSIBILITY OF MCS DEVELOPMENT IN LAKE MARACAIBO REGION IN
VENEZUELA/SANTANDERES IN COLOMBIA.

EASTERLY/TROPICAL WAVES (INITIALIZED AT 12Z TODAY)

INITIAL      F24   F36   F48   F60   F72   F84
28W (S/17N)  32W   39W   43W   47W   51W   54W
49W (S/16N)  53W   59W   64W   68W   74W   78W
66W (S/12N)  69W   72W   75W   77W   79W   82W
71W (S/16N)  75W   77W   80W   82W   85W   87W
87W(TUTT)    89W   91W   94W   97W   99W   101W
96W (S/21N)  98W   102W  106W  109W  112W  115W

THE WAVE ALONG 28W WILL REACH THE GUIANAS ON DAY 03... TO FAVOR
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20- 35MM.

THE WAVE ALONG 49W IS A PROGRESSIVE PERTURBATION. IT IS TO ENTER
THE ISLAND CHAIN BY 36-39 HRS. MODELS CONSISTENTLY SHOW BEST
DYNAMICS TO THE WEST OF THE TROUGH AXIS...WITH CONVECTION TO
LIKELY PRECEDE THIS FEATURE. ALTHOUGH SOMEWHAT SLOWER THAN
YESTERDAY...THE MODELS CONTINUE TO SUSTAIN A VERY PROGRESSIVE WAVE
PATTERN/WIND SURGE...AND FAVOR ACCELERATION OF THIS FEATURE AS IT
MOVES ACROSS THE EASTERN CARIBBEAN. THE GFS SHOWS 850 HPA WINDS OF
35-50KT BEHIND THIS WAVE AND OVER THE ISLAND CHAIN BY 36-42
HRS...TO RAPIDLY ENVELOP THE EASTERN-CENTRAL CARIBBEAN THROUGH
60-84 HRS. A DRY/STABLE AIR MASS IS TO FOLLOW THIS WAVE...WITH
SAHARA DUST TO RESTRICT VISIBILITY. THE RAPID NATURE OF THIS WAVE
WILL LIKELY FAVOR SQUALLY WEATHER OVER THE LESSER ANTILLES-VIRGIN
ISLES AND PUERTO RICO. SEVERE CONVECTION IS PROBABLE... HIGHEST
RISK ON DAY 02 WHEN THE WAVE IS EXPECTED TO ACCELERATE. OVER
NORTHERN GUYANA-NORTHEAST VENEZUELA AND THE WINDWARD ISLES IT WILL
FAVOR RAINFALL AMOUNTS OF 10-20MM/DAY AND MAXIMA OF 25-50MM BY
30-42 HRS. OVER THE LEEWARD-VIRGIN ISLANDS WE EXPECT ACCUMULATION
OF 05-10MM/DAY AND MAXIMA OF 20-35MM...WHILE OVER PUERTO RICO AND
THE DOMINICAN REPUBLIC IT WILL FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 30-60MM. OVER VENEZUELA...IN INTERACTION
WITH THE NEAR EQUATORIAL TROUGH...IT WILL FAVOR RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 30-65MM...WITH POSSIBILITY OF AN MCS
OVER LAKE MARACAIBO ON DAY 03. OVER SANTANDERES AND SIERRA DE
SANTA MARTA IN COLOMBIA THE MAXIMA IS LIKELY TO PEAK AT 40-80MM.

THE PERTURBATIONS ALONG 66W AND 71W CONTINUE TO INTERACT WITH THE
NEAR EQUATORIAL TROUGH AS THEY MOVE ACROSS VENEZUELA-COLOMBIA.
OVER CENTRAL/WESTERN VENEZUELA TO EASTERN AND NORTHERN COLOMBIA IT
WILL FAVOR RAINFALL ACCUMULATION OF 15-25MM/DAY AND MAXIMA OF
30-65MM/DAY. THE MOST INTENSE IS EXPECTED BETWEEN GULF OF
URABA/EJE CAFETERO BY MID CYCLE WITH MAXIMA OF 40-80MM...WHILE
ACROSS THE DARIEN TO CENTRAL PANAMA EXPECT ACCUMULATION OF
10-15MM/DAY AND MAXIMA OF 20-40MM/DAY.

THE TROUGH ALONG 87W IS A TUTT INDUCED PERTURBATION...IN
ASSOCIATION WITH UPPER TROUGH MEANDERING OVER THE CENTRAL
CARIBBEAN. THIS TROUGH IS TO ENHANCE CONVECTION ACROSS EASTERN
NICARAGUA/NORTHEAST HONDURAS...WHERE IT WILL FAVOR RAINFALL
AMOUNTS OF 10-20MM/DAY AND MAXIMA OF 30-60MM/DAY. OVER
BELIZE-QUINTANA ROO IN THE YUCATAN AND EL SALVADOR IT WILL FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM/DAY. OVER
GUATEMALA TO SOUTHERN MEXICO WE EXPECT ACCUMULATION OF 15-25MM/DAY
AND MAXIMA OF 30-60MM.

THE WAVE ALONG 96W WILL FAVOR ORGANIZED CONVECTION ALONG THE
EASTERN PACIFIC ITCZ AND THE SOUTHERN STATES OF MEXICO... FROM
OAXACA-GUERRERO TO MICHOACAN-COLIMA WHERE IT WILL FAVOR RAINFALL
AMOUNTS OF 10-20MM/DAY AND MAXIMA OF 30-70MM. MAXIMA ON THE SIERRA
MADRE DEL SUR WILL PEAK AT 75-125MM DUE TO STRONG TOPOGRAPHICAL
FORCING AND INTERACTION WITH THE TUTT ALOFT.

ALBERT...NWS (SAINT LUCIA)
ALVARADO...ETESA (PANAMA)
DAVISON...NCEP  (USA)