[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031147
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON DEC 03 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1115 UTC

...THE ITCZ...
ITCZ IS CENTERED ALONG 7N12W 6N23W 7N35W 5N42W 3N51W. AXIS IS
ACTIVE THIS MORNING WITH SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVERING A LARGE AREA FROM 4N-8N BETWEEN 17W-31W.
SIMILAR CONVECTION IS WITHIN 150 NM OF THE AXIS E OF 14W AND
BETWEEN 31W-34W. A SFC TROUGH ALONG 43W/44W IS ENHANCING
SCATTERED MODERATE/ISOLATED STRONG FROM 4N-9N BETWEEN 38W-47W.

DISCUSSION...

THE GULF OF MEXICO...
A DIGGING MID TO UPPER SHORTWAVE OVER THE NW GULF IS SUPPORTING A
COLD FRONT...WHICH AS OF 09Z EXTENDED FROM THE WRN FL PANHANDLE
TO JUST S OF BROWNSVILLE TEXAS NEAR 25N98W. LOW-LEVEL
CONVERGENCE NEAR THE BOUNDARY IS GENERATING A NARROW LINE OF
SCATTERED SHOWERS AND TSTMS WITHIN 60 NM AS NOTED IN MOSAIC
DOPPLER RADAR. NW GULF BUOYS SHOW NLY WINDS SIGNIFICANTLY
INCREASING UP TO 30 KT WITH HIGHER GUSTS BEHIND THE FRONT. THIS
STRONG FLOW IS ADVECTING A COOLER AND MUCH DRIER AIRMASS INTO
THE NW WATERS. DEWPOINTS HAVE FALLEN INTO THE 20'S F ACROSS MUCH
OF TEXAS AND A ONE HOUR 17 DEG F DEWPOINT DROP WAS REPORTED IN
BROWNSVILLE. THE REMAINDER OF THE GULF IS VERY TRANQUIL AT THE
MOMENT WITH LIGHT AND VARIABLE WINDS AND ONLY A FEW PATCHY
CLOUDS SUPPRESSED BY WIDESPREAD STABLE AIR ALOFT. THE FRONT IS
EXPECTED TO CONTINUE ITS SE PROGRESS ALLOWING THE AIRMASS
CHANGE...ALBEIT MODIFYING ...TO SPREAD ACROSS MOST OF THE AREA
WITHIN THE NEXT 24-36 HOURS.

THE CARIBBEAN SEA...
BRISK LOW-LEVEL NE WINDS TO THE W OF A LOW PRES SYSTEM IN THE
CENTRAL ATLC IS DRIVING STREAMS OF LOW-LEVEL CLOUDS AND SHOWERS
ACROSS THE LEEWARD ISLANDS AND INTO THE CENTRAL CARIB ROUGHLY
FROM 14N-17N E OF 78W. THIS CLOUDINESS IS DEEPEST ROUGHLY MIDWAY
BETWEEN SOUTH AMERICA AND HISPANIOLA LIKELY DUE TO WIND SPEED
CONVERGENCE WHICH WAS CLEARLY EVIDENT IN EARLIER ASCAT DATA.
HIGHLY ELONGATED MID TO UPPER TROUGHING AND VERY DRY AIR ALOFT
COVERS MUCH OF THE CENTRAL AND E CARIB. THIS IS HELPING TO KEEP
MOST OF THE MENTIONED SHOWER ACTIVITY FAIRLY SHALLOW. THE WRN
CARIB IS EXPERIENCING FAIR WEATHER UNDER THE INFLUENCE OF MID TO
UPPER RIDGING AND ABUNDANT SUBSIDENCE. NELY TRADE WIND FLOW IS
STRONGEST...20-25 KT...IN THE N CENTRAL CARIB THIS MORNING.
THESE WINDS ARE EXPECTED TO SLACKEN BELOW 20 KT BASIN WIDE
AROUND THIS TIME TOMORROW.

THE ATLANTIC OCEAN...
VERTICALLY STACKED RIDGING IS THE THEME ACROSS THE W ATLC. WATER
VAPOR IMAGERY SHOWS AN EXTENSIVE AREA OF DRY AIR S OF 22N W OF
55W BUT THIS IS SOMEWHAT DECEIVING AS SCATTERED TO BROKEN
PATCHES OF CLOUDINESS/SHOWERS LIE UNDERNEATH THIS INVERSION.
THE SFC HIGH CENTER IS ANALYZED 1023 MB VERY NEAR BERMUDA
ALLOWING ELY WINDS TO BE LIGHT N OF 27N AND MODERATE TO FRESH S
OF THERE. IN THE CENTRAL ATLC...A SLOWLY WEAKENING FRONTAL
BOUNDARY IS ANALYZED FROM 32N43W TO 25N55W THEN DISSIPATING TO
23N69W. THIS FRONT APPEARS AS IF IS ABOUT TO MERGE WITH A
QUASI-STATIONARY 1010 MB LOW NEAR 23N52W. SHIP BATFR13 JUST W OF
THE LOW CENTER HAS BEEN VERY HELPFUL IN ANALYZING THE MIN PRES.
CONVECTION HAS BEEN ON A STEADY DECREASE OVERNIGHT WITH ONLY
ISOLATED MODERATE REMAINING FROM 21N-24N BETWEEN 48W-51W.  A
LARGER AREA OF CLOUDINESS AND EMBEDDED SCATTERED SHOWERS IS
LOCATED TO THE E OF THE SFC LOW IN AN UPPER DIFFLUENT ZONE
BETWEEN 37W-45W N OF 18N. ANOTHER QUASI-STATIONARY SFC TROUGH IS
ALONG 55W/56W FROM 9N-16N. NIGHT CHANNEL VIS IMAGES AND ASCAT
DATA SUGGESTS THAT AN ILL STRUCTURED 1010 MB LOW HAS FORMED
ALONG THE TROUGH AXIS NEAR 13N. SCATTERED SHOWERS AND TSTMS ARE
LOCATED TO THE E OF THE TROUGH/LOW... SHEARED BY UPPER SWLY
FLOW...FROM 13N-15N BETWEEN 52W-54W.

THE ERN ATLC IS DOMINATED BY SFC RIDGING EXTENDING SWD FROM A
1028 MB HIGH MIDWAY BETWEEN THE AZORES AND THE IBERIAN
PENINSULA. NE TO ELY TRADES ARE STRONGEST FROM 14N-25N E OF THE
CAPE VERDE ISLANDS AS SUGGESTED BY RECENT SCATTEROMETER PASSES.
THE MID AND UPPER FLOW IS MAINLY W TO NW ACROSS THIS REGION
BETWEEN RIDGING STRETCHING NWD FROM THE EQUATOR...AND A HIGHLY
ELONGATED UPPER TROUGH EXTENDING SW FROM EUROPE THRU THE CANARY
ISLANDS. STRONG FLOW BETWEEN THESE SYSTEMS IS ADVECTING HIGH
LEVEL CLOUDINESS MAINLY S OF 22N. A WEAK UPPER LOW CENTERED NEAR
29N24W IS PRODUCING SIMILAR CLOUDINESS WITHIN 90 NM OF THE
CENTER.

$$
CANGIALOSI


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