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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1905Z Jan 29, 2015)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
205 PM EST THU JAN 29 2015

DISCUSSION FROM JANUARY 29/00UTC: DEEP MID LEVEL TROUGH ON THE
SOUTHERN STREAM EXTENDS ACROSS THE BAJA PENINSULA TO THE TROPICAL
PACIFIC. THIS TROUGH IS TO PRESS AGAINST A RIDGE TO THE EAST...AND
IN THIS PROCESS IT IS TO THEN SHEAR SHORT WAVE ENERGY ACROSS BAJA
PENINSULA-SONORA/CHIHUAHUA IN NORTHWEST MEXICO. THE HIGH AMPLITUDE
TROUGH IS TO INTERACT WITH THE ITCZ TO THE SOUTH...DRAWING DEEP
MOISTURE ACROSS THE BAJA PENINSULA/NORTHWEST STATES OF MEXICO.
STRONG CYCLONIC VORTICITY ADVECTION WILL COMBINE WITH THE HIGH
TERRAIN OF THE SIERRA MADRE TO RESULT IN AREAS OF ORGANIZED HEAVY
CONVECTION. ACROSS NORTHWEST MEXICO EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM THROUGH FRIDAY MORNING...AND
15-20MM/DAY AND MAXIMA OF 25-50MM ON FRIDAY TO SATURDAY. EARLY ON
SATURDAY FOCUS OF THE CONVECTION SHIFTS TO SONORA MEXICO...WHERE
WE ALSO EXPECT RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM. OTHER CONVECTION IS TO THEN BUILD EAST ACROSS THE
NORTH-CENTRAL TO NORTHEASTERN STATES OF MEXICO...WITH ACCUMULATION
OF 00-05MM/DAY AND MAXIMA OF 10MM.

MID/UPPER LEVEL RIDGE PATTERN IS TO INITIALLY CONFINE TO
MEXICO-NORTHERN CENTRAL AMERICA...WHILE ANCHORING ON A CLOSED HIGH
OVER COLIMA/NAYARIT TO THE SOUTHWEST OF MEXICO. THROUGH SATURDAY
MORNING THE RIDGE RELOCATES TO THE CENTRAL CARIBBEAN AS IT YIELDS
TO THE DEEP SOUTHERN STREAM TROUGH. THIS IS TO THEN BECOME THE
DOMINANT FEATURE ACROSS THE CARIBBEAN BASIN LATER DURING THE
WEEKEND. AS THE RIDGE MOVES TO THE EAST...CAP INVERSION OVER
MEXICO IS TO WEAKEN. HOWEVER...OPPOSITE IS TRUE ACROSS THE
CARIBBEAN BASIN...WITH RIDGE TO STRENGTHEN CAP INVERSION AS THE
CYCLE PROGRESSES.

DOWNSTREAM FROM THE MID LEVEL RIDGE...OVER THE WESTERN
ATLANTIC...A BROAD POLAR TROUGH EXTENDS SOUTH TO THE NORTHERN
CARIBBEAN ISLES. THE TROUGH IS LIFTING AS IT MEANDERS TO THE
EAST-NORTHEAST...AND EARLY ON FRIDAY IT IS FORECAST TO PULL.
ASSOCIATED FRONT...MEANWHILE...IS TO EXTEND ACROSS NORTHERN
HISPANIOLA TO THE NORTHWEST CARIBBEAN. THROUGH FRIDAY MORNING IT
MEANDERS NORTH TO THE SOUTHEAST BAHAMAS/TURKS-CUBA...AND THROUGH
SATURDAY MORNING IT IS EXPECTED TO FRONTOLIZE. MEANWHILE...THIS IS
TO ENHANCE MOISTURE CONVERGENCE ACROSS NORTHERN HISPANIOLA TO
FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM.
ACROSS THE SOUTHEAST BAHAMAS/EASTERN CUBA IT IS TO THEN FAVOR
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.

ANOTHER TROUGH IS TO CLEAR THE EASTERN SEABOARD OF THE USA BY
MIDAFTERNOON ON FRIDAY...TO MEANDER EAST ACROSS 60W LATER ON
SATURDAY. AS RIDGE BUILDS TO THE SOUTH ACROSS THE BASIN...THE
TROUGH IS FORECAST TO BOTTOM OUT FAR TO THE NORTH. ASSOCIATED
FRONT MOVES TO THE WESTERN ATLANTIC EARLY ON FRIDAY...AND LATER IN
THE DAY IT IS TO EXTEND ACROSS CENTRAL FLORIDA TO THE NORTHERN
GULF OF MEXICO. EARLY ON SATURDAY MORNING IT IS TO ENTER THE
NORTHWEST BAHAMAS...AND DURING THE EVENING HOURS THE FRONT MOVES
TO THE CENTRAL BAHAMAS-STRAITS OF FLORIDA TO THE NORTHERN
GULF/SOUTHERN USA. BUT LACKING UPPER LEVEL SUPPORT...EARLY ON
SUNDAY MORNING THE FRONT IS TO STALL ALONG 21N/22N. BUILDING POLAR
RIDGE ACROSS THE GULF OF MEXICO IS TO THEN TRIGGER A PREFRONTAL
SHEAR LINE ACROSS THE BASIN. THIS IS TO FORM LATER ON FRIDAY/EARLY
SATURDAY MORNING...WITH AXIS ACROSS HISPANIOLA TO THE CENTRAL
CARIBBEAN/COSTA RICA-SOUTHERN NICARAGUA. WINDS OF 20-25KT ARE TO
ACCOMPANY THIS FEATURE AS IT PULLS ACROSS THE BASIN. LATER ON
SATURDAY IT MOVES ACROSS PUERTO RICO-VIRGIN ISLES WHILE TRAILING
TO THE CENTRAL CARIBBEAN. AS THE FRONT MOVES OVER THE BAHAMAS IT
IS TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.
ACROSS NORTHERN HISPANIOLA...THE SHEAR LINE IS TO SUSTAIN RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM DURING THE DAY ON
FRIDAY TO EARLY SATURDAY...WHILE ACROSS PUERTO RICO EXPECTING
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM. AS IT TRAILS TO
COSTA RICA/SOUTHERN NICARAGUA IT IS TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY...WITH MAXIMA OF 15-20MM LATER ON SATURDAY AS IT MOVES
TOWARDS WESTERN PANAMA.

BUILDING LOW LEVEL RIDGE ACROSS THE GULF-CARIBBEAN IS TO
STRENGTHEN THE TRADE WIND EASTERLIES ACROSS THE CENTRAL/WESTERN
CARIBBEAN AND OVER CENTRAL AMERICA. AT 850 HPA THE WINDS ACROSS
NICARAGUA ARE EXPECTED TO PEAK AT 30-35KT...WITH LOCALLY STRONGER
WINDS LIKELY OVER WESTERN NICARAGUA. THESE WINDS ARE TO CONVERGE
ON THE CARIBBEAN PLAINS OF COSTA RICA-BOCAS DEL TORO IN WESTERN
PANAMA AND SOUTHERN NICARAGUA...TO SUSTAIN RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM. OVER COLOMBIA...COLD WATER
UPWELLING ALONG THE WEST COAST HAS RESULTED IN A PWAT MINIMA AND
WELL BELOW NORMAL RAINFALL AMOUNTS. STRONG WINDS ARE LIKELY TO
PERSIST OVER THE NEXT FEW DAYS...WITH MOSTLY FAVORABLE WEATHER
CONDITIONS EXPECTED TO PREVAIL THROUGH SATURDAY MORNING.
HOWEVER...MOISTURE STARTS TO SURGE DURING THE DAY...WITH DIURNAL
CONVECTION ALONG THE ANDES AND COASTAL PLAINS TO RESULT IN
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. MOST ACTIVE
CONVECTION IS EXPECTED TO THE SOUTH ALONG THE BORDER WITH
ECUADOR....WHERE ITCZ CONVERGENCE IS TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM. INLAND OVER AMAZONIA IN
COLOMBIA...A SURGE IN ACTIVITY IS EXPECTED ON FRIDAY-SUNDAY
MORNING...WITH DAILY RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
30-60MM.

OVER THE GUIANAS...MEANWHILE...A SOUTHERN HEMISPHERE TUTT LOW NEAR
10S 41W EXTENDS A TROUGH TO THE NORTHWEST ACROSS THE GUIANAS. THIS
TROUGH IS TO SLOWLY WEAKEN THROUGH SATURDAY EVENING.
MEANWHILE...IT IS TO ENHANCE CONVECTIVE DEVELOPMENT ACROSS THE
GUIANAS. OVER SURINAME TO FRENCH GUIANA EXPECTING RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-35MM. THIS IS EXPECTED TO DECREASE
TO 05-10MM/DAY AND MAXIMA OF 15MM LATER IN THE CYCLE. ACROSS
GUYANA EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF
15-20MM. THROUGH SATURDAY EVENING THIS DECREASES TO 05-10MM/DAY
AND MAXIMA OF 15MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
NONE

JN BAPTISTE...MS (SAINT LUCIA)
NANDA...MDS (SURINAME)
DAVISON...WPC (USA)