[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301725
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN APR 30 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...
RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N12W 4N20W 3N30W 1N40W EQ50W.
NUMEROUS CLUSTERS OF MODERATE/STRONG CONVECTION EXISTS FROM THE
EQUATOR TO 8N E OF 20W. THE STRONGEST CONVECTION IS OFF THE
COAST OF W AFRICA E OF 5W. SCATTERED SHOWERS AND TSTMS ARE
WITHIN 150 NM OF THE AXIS BETWEEN 20W-37W. ORGANIZING CLUSTERS
OF MODERATE CONVECTION IS ALONG AND S OF THE AXIS W OF 37W TO
INLAND OVER BRAZIL. SWLY UPPER LEVEL FLOW IS SHEARING SOME OF
THE TSTMS TO THE NE W OF 45W.

...DISCUSSION...
THE GULF OF MEXICO...
MID-UPPER LEVEL CLOUDINESS COVERS MUCH OF THE REGION WITH THE
DEEPEST MOISTURE ACROSS THE W/CENTRAL GULF. A SWLY UPPER LEVEL
JET RUNS FROM NEAR TAMPICO MEXICO TO MORGAN CITY LOUISIANA. AT
THE SFC...A COLD FRONT EXTENDS FROM E LOUISIANA TO 26N94W THEN
BECOMES A DISSIPATING STATIONARY FRONT TO 21N98W. SFC FORCING
AND UPPER LEVEL DIFFLUENCE IS PRODUCING A SHIELD OF SHOWERS AND
STORMS FROM 22N TO BEYOND 32N BETWEEN 86W-97W. EAST OF THE
BOUNDARY...SFC RIDGING FROM A 1025 MB HIGH OVER S CANADA IS
SQUEEZING INTO THE AREA BETWEEN LOW PRES SYSTEMS TO THE E OVER
THE W ATLC AND TO THE W OVER THE CENTRAL U.S. THE TIGHT PRES
GRAD IS GENERATING STIFF E/SELY FLOW NEAR 20-30 KT. EVEN
STRONGER WINDS...NEAR 30-35 KT...ARE OBSERVED S OF THE U.S. GULF
COAST E OF THE FRONT ESPECIALLY IN AREAS OF PRE-FRONTAL
CONVECTION. AS OF 1500 UTC...A SQUALL LINE LIES AHEAD OF THE
FRONT FROM 27N91W TO 29N88W. THIS LINE OF TSTMS IS BEGINNING TO
FALL APART WITH NEW CONVECTION FIRING FURTHER TO THE S ALONG THE
FRONT. WEST OF THE SUB-TROPICAL JET AXIS...UPPER LEVEL CONFLUENT
FLOW IS ENHANCING DRY/STABLE AIR ALOFT ACROSS THE EXTREME NW
GULF...N MEXICO AND THE S CENTRAL U.S. COMPUTER MODELS
ANTICIPATE THE NORTHERN PART OF THE FRONT IN THE AREA TO PRESS
SEWD AND WEAKEN. REMNANT MOISTURE FROM THE TAIL END OF THE FRONT
AND WEAKENING SWLY JET WILL REMAIN IN THE CENTRAL/SW GULF THRU
TUE. THEREAFTER...WEAK SFC HIGH PRES WILL DEVELOP OVER THE E
GULF.

THE CARIBBEAN SEA...
AN UPPER HIGH IS CENTERED IN THE W CARIBBEAN NEAR 15N81W
GENERATING MODERATE TO STRONG SUBSIDENCE ACROSS MUCH OF THE
AREA. THE DRIEST AIR ALOFT IS E OF 74W S OF 17N WHERE UPPER
LEVEL CONFLUENCE IS THE STRONGEST. CLUSTERS OF MODERATE TO
STRONG CONVECTION IS OVER COLUMBIA AND OFF THE W COAST OF COSTA
RICA. THE TAIL END OF A STRONG W ATLC COLD FRONT EXTENDS THRU
THE MONA PASSAGE. SAN JUAN DOPPLER RADAR INDICATES A LINE OF
SHOWERS AND TSTMS ALONG THE FRONT IN THE PASSAGE MOVING ACROSS
THE NW CORNER OF PUERTO RICO WITH SOME SCATTERED PRE-FRONTAL
SHOWERS ACROSS THE REST OF THE ISLAND AND THE VIRGIN ISLANDS.
N/NE SFC WINDS FROM 15-20 KT IS COMMON ACROSS THE THE NW
CARIBBEAN. THIS FLOW IS UPSLOPING THE TOPOGRAPHY IN
HISPANIOLA...E CUBA AND JAMAICA GENERATING SCATTERED SHOWERS AND
POSSIBLE TSTMS. TRADE WINDS ARE FAIRLY LIGHT ACROSS THE S
CARIBBEAN E OF 80W...WINDS SHOULD REMAIN LIGHT TO MODERATE THRU
THE EARLY PART OF THE WEEK AS LOW PRES TO THE N OF THE REGION
PULLS NWD. THE TAIL END OF THE COLD FRONT WILL LIKELY BECOME
STATIONARY OR QUASI-STATIONARY KEEPING MOISTURE ACROSS THE E
CARIBBEAN THRU MID-WEEK.

THE ATLANTIC OCEAN...
HIGH PRES OVER S CANADA IS CAUSING FAIR WEATHER ACROSS THE
EXTREME W ATLC W OF 75W. A LARGE AREA OF CYCLONIC SPIN WITH TWO
EMBEDDED LOW CENTERS...1005 MB LOW NEAR 31N67W AND 1007 MB LOW
NEAR 30N68W...IS PRODUCING STORM FORCE WINDS. A SFC TROUGH WRAPS
AROUND TO THE S SEMI-CIRCLE OF THE 1007 MB LOW. A COLD FRONT
EXTENDS FROM THE 1005 MB LOW ALONG 28N63W 21N65W TO THE MONA
PASSAGE. A WIDE BAND OF RAIN IS WITHIN 300 NM AHEAD OF THE FRONT
N OF 21N WITH MOISTURE MORE DIFFUSE NEAR THE GREATER ANTILLES.
THIS RATHER LARGE SYSTEM HAS BEEN SLOW TO MOVE AND WILL LIKELY
CONTINUE TO MEANDER FOR THE NEXT 24-36 HOURS. FARTHER EAST...SFC
RIDGING FROM A 1032 MB HIGH WELL N OF THE AREA IS PRODUCING FAIR
WEATHER ACROSS MUCH OF THE CENTRAL AND EASTERN ATLC.
HOWEVER...CONTAMINATING THE RIDGE IS A 1012 MB LOW NEAR 29N30W.
THIS AREA OF LOW PRES APPEARS TO BE NEARLY STATIONARY AND IS
GENERATING SOME SHOWER ACTIVITY WITHIN 300 NM OF THE CENTER OF
CIRCULATION. GLOBAL MODELS DO NOT INITIALIZE THIS FEATURE AT THE
SFC. UPPER LEVEL SWLY FLOW IS ENHANCING BANDS OF CLOUDS WITH
EMBEDDED SHOWERS AND ISOLATED TSTMS BETWEEN 30W-60W S OF 21N.
MUCH OF THE ATLC APPEARS TO BE A IN A BLOCKING PATTERN WITH
FEATURES QUASI-STATIONARY. THIS IS LIKELY TO HOLD FOR THE NEXT
DAY COUPLE OF DAYS BEFORE A MORE ZONAL UPPER LEVEL PATTERN
DEVELOPS BY MID-WEEK.

$$
CANGIALOSI




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