[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 011742
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN APR 1 2007

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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

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

...THE ITCZ...
AXIS IS CENTERED ALONG 6N10W 3N21W 1N31W EQ45W 1S51W. SCATTERED
MODERATE CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE AXIS
BETWEEN 18W-27W AND 34W-44W. SIMILAR ACTIVITY HAS DEVELOPED
WITHIN 60 NM OF AXIS BETWEEN 13W-16W. NUMEROUS
MODERATE/SCATTERED STRONG IS E OF 1W FROM THE EQ TO 8N.

...DISCUSSION...

GULF OF MEXICO...
SCATTERED SHOWERS AND TSTMS LIE IN THE W GULF AHEAD OF A
STALLED FRONTAL BOUNDARY WHICH EXTENDS FROM ERN TEXAS ACROSS
BROWNSVILLE INTO A SMALL PORTION OF NRN MEXICO. SFC OBS SUPPORT
A 1013 MB FRONTAL WAVE S OF CORPUS CHRISTI. LOW-LEVEL
CONVERGENCE ALONG AND AHEAD OF THE FRONT AS WELL AS EXTENSIVE
SWLY FLOW ALOFT AND DIFFLUENCE ARE THE TRIGGERING FACTORS FOR
THE SHOWERS AND STORMS LINED UP N OF 21N BETWEEN 91W-97W. THE
REMAINDER OF THE GULF IS RATHER QUIET...MOISTURE-WISE...UNDER
THE INFLUENCE OF A MID LEVEL HIGH IN THE SE GULF NEAR 23N86W.
THERE IS A BROKEN CIRRUS LAYER SPREADING ACROSS MUCH OF THE
REGION...BUT THIS IS ONLY FILTERING SUNSHINE. AT THE SFC...THE W
PERIPHERY OF A 1026 MB HIGH CENTERED IN THE SW ATLC STRETCHES
THRU THE MIDDLE GULF. THE RATHER TIGHT PRES GRADIENT SET UP
BETWEEN THIS HIGH AND LOWER PRES IN THE W GULF IS PRODUCING A
LARGE AREA OF 15-20 KT S-SE WINDS AS DEPICTED BY THIS MORNING
QSCAT PASS.

LOOKING AHEAD INTO THE BEGINNING OF THE WORK WEEK...SEVERAL NWP
MODELS SHOW THE ACTIVE FRONTAL BOUNDARY BACKING UP AND BECOMING
DIFFUSE THRU TOMORROW. THIS WILL ALLOW SFC HIGH PRES TO STRETCH
FURTHER W COVERING NEARLY THE ENTIRE AREA. AS THIS OCCURS...THE
SFC WINDS WILL COME DOWN SLIGHTLY AS THE PRES GRAD LOOSENS.
HOWEVER...A FAIR AMOUNT OF MOISTURE IS LIKELY TO REMAIN IN THE
WRN GULF AS THE REGION REMAINS IN THE VICINITY OF AN UPPER
DIFFLUENT ZONE.

CARIBBEAN SEA...
THE MODERATE TO STRONG TRADES...PRODUCED BY A HIGH PRES RIDGE
CENTERED BETWEEN BERMUDA AND THE SE U.S. COAST...IS THE
HIGHLIGHT ACROSS THE CARIB TODAY. THESE STIFF WINDS ARE
GENERATING AND DRIVING PATCHES OF LOW-MID LEVEL CLOUDS AND
EMBEDDED ISOLATED SHOWERS ACROSS THE SEA. THERE IS SOME POOLING
OF MOISTURE OVER ERN NICARAGUA AND HONDURAS WHERE ISOLATED TO
SCATTERED SHOWERS ARE LIKELY. ALOFT...AN EXTENSIVE RIDGE
CENTERED ABOVE THE TROPICAL ATLC IS PRODUCING S-SWLY UPPER FLOW
AND SCATTERED CLOUDINESS ACROSS THE CENTRAL AND ERN CARIB. THE
CLOUDS/SHOWERS ARE DEEPEST OVER THE LESSER ANTILLES WHERE THERE
APPEARS TO BE LOW-LEVEL SPEED CONVERGENCE NEAR THE TAIL END OF A
DISSIPATING FRONT. UPPER CONFLUENCE IS PROVIDING A VERY STABLE
ENVIRONMENT ABOVE THE MOIST LOW-LAYERS N OF 17N W OF 65W.

THE PRES GRADIENT IS EXPECTED TO REMAIN RATHER TIGHT OVER THE
NEXT DAY OR TWO KEEPING THE TRADE FLOW MODERATE TO STRONG AND
CAUSING SIMILAR WX CONDITIONS ACROSS THE REGION.

ATLANTIC OCEAN...
A VERTICALLY STACKED RIDGE/TROUGH/RIDGE PATTERN EXISTS ACROSS
THE ATLC DISCUSSION AREA. THE WRN-MOST ATLC IS COVERED BY A
LAYERED RIDGE WITH THE UPPER AXIS RUNNING FROM THE SE BAHAMAS TO
BEYOND THE MID-ATLANTIC STATES. THE FLOW ALOFT INCREASES AND
BECOMES RATHER ZONAL E OF THE RIDGE AXIS OUT TO ABOUT 40W IN
RESPONSE TO A STRONG TROUGH MOSTLY N OF THE AREA. THIS CONFLUENT
FLOW IS DRYING OUT THE ATMOSPHERE...ABOVE THE LOW-LEVEL
INVERSION BETWEEN 35W-75W. AT THE SFC...AN ASSOCIATED COLD FRONT
ENTERS THE AREA NEAR 32N37W AND EXTENDS SSW ALONG 26N39W 20N44W
THEN AS A DISSIPATING STATIONARY FRONT TO 15N57W. LOW-LEVEL
CONVERGENCE AND UPPER LEVEL DIFFLUENCE IS PRODUCING A SWATH OF
SCATTERED SHOWERS WITHIN 240 NM E OF THE BOUNDARY. TWO OTHER
REINFORCING FRONTS ARE LINED UP BEHIND THIS MAIN ONE. THE FIRST
REINFORCEMENT ENTERS THE AREA NEAR 32N47W TO JUST S OF BERMUDA.
THE OTHER IS STILL WELL N OF THE AREA. THESE REINFORCING
BOUNDARIES CARRY LIMITED MOISTURE AND MAINLY ACT AS A SURGE IN
THE WINDS ADVECTING COLDER AIR SWD...AS CLEARLY REPRESENTED BY
THE LARGE FIELD OF COLD AIR STRATO-CU CLOUDS. THE REMAINDER OF E
ATLC IS DOMINATED BY THE SRN PERIPHERY OF HIGH PRES WELL N OF
THE AREA. THIS IS PRODUCING ABUNDANT 10-20 KT E/NE WINDS AND
FAIR WEATHER E OF 30W.

$$
CANGIALOSI




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