[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271119
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON NOV 27 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1100 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 5N30W 4N47W 3N53W. SCATTERED
MODERATE CONVECTION IS WITHIN 120 NM N AND 180 NM S OF THE AXIS
E OF 22W. THE REMAINDER OF THE AXIS IS RATHER QUIET WITH ONLY
ONE AREA OF SCATTERED MODERATE WITHIN 60 NM EITHER SIDE BETWEEN
32W-35W.

...DISCUSSION...
THE GULF OF MEXICO...
THE WEATHER ACROSS THE GULF REMAINS FAIRLY UNEVENTFUL AS SFC
HIGH PRES CONTINUES TO DOMINATE THE AREA. BREEZY 15-20 KT NE TO
E WINDS IN THE ERN AND CNTRL GULF IS ADVECTING SOME LOW-LEVEL
CLOUDS AND ISOLATED SHOWERS ACROSS CENTRAL AND SOUTH FLORIDA ON
THE BREEZE WITH SOME BROKEN CLOUDS PUSHING W ACROSS THE GULF
WATERS. HOWEVER...BECAUSE OF THE WIDESPREAD STRONG SUBSIDENCE
ABOVE THE LOW-LAYER OF MOISTURE THERE IS LIMITED DEPTH TO THE
CLOUDS. THE SFC FLOW IS A LITTLE LIGHTER AND IS MORE ESELY IN
THE WRN GULF FLOWING CLOCKWISE AROUND THE 1028 MB SFC HIGH
CENTERED IN NE GEORGIA. IN THE UPPER LEVELS...A PRONOUNCED RIDGE
CENTERED IN THE SW GULF HAS RIDGING THAT EXTENDS ACROSS THE
CENTRAL GULF AND INTO THE OHIO VALLEY. SLIGHT UPPER TROUGHING IS
LIFTING OUT BUT STILL LIES ABOVE SE FLORIDA. GFS SHOWS THE UPPER
AND SFC RIDGE BUILDING E. THIS WILL ALLOW TEMPS TO REMAIN
SLIGHTLY ABOVE NORMAL VALUES OVER THE NEXT FEW DAYS. THE NEXT
AIRMASS CHANGE IS ANTICIPATED TO AFFECT THE AREA LATE IN THE
WEEK AS A POTENTIAL STRONG COLD FRONT APPROACHES THE NW PORTION
ON THU. GALE CONDITIONS ARE FORECAST BEHIND THE FRONT AS STRONG
HIGH PRES BUILDS IN.

THE CARIBBEAN SEA...
THE UNSETTLED WEATHER THAT HAS BEEN IN THE SW CARIBBEAN OVER THE
PAST SEVERAL DAYS...ASSOCIATED WITH A NEARLY STATIONARY SFC LOW
PRES TROUGH ALONG 77W FROM 10N-16N...HAS DIMINISHED. THE FEATURE
IS STILL EVIDENT...BARELY...BUT IS NOW VERY SHALLOW WITH ONLY
LOW TO MID-LEVEL CLOUDS VEERING ABOUT THE AXIS. THE TAIL END OF
A SLOWLY WEAKENING STATIONARY FRONT EXTENDS ACROSS THE WINDWARD
PASSAGE TO JUST W OF JAMAICA NEAR 17N76W. DEEP MOISTURE IS VERY
LIMITED ALONG THE FRONT WITH ONLY ISOLATED SHOWERS WITHIN 120 NM
OF THE SFC BOUNDARY. S-SWLY UPPER LEVEL FLOW...ASSOCIATED WITH A
VERY BROAD FLAT RIDGE CENTERED OVER VENEZUELA...IS DRAWING SOME
MOISTURE FROM THE ITCZ AND SPREADING IT ABOVE THE SFC FRONT INTO
THE ATLC. HOWEVER...AS MENTIONED...THE MOISTURE PLUME IS
SIGNIFICANTLY THINNER THAN IT HAS BEEN WITH ONLY BROKEN MID-HIGH
LEVEL CLOUDINESS AND EMBEDDED ISOLATED SHOWERS NOTED BETWEEN
72W-83W. VERY DRY AIR/STRONG SUBSIDENCE LIES ABOVE THE ERN AND
THE EXTREME WRN CARIB SUPPRESSING ANY DEEP CLOUDINESS. TRADES
ARE MODERATE AND WILL LIKELY REMAIN THAT WAY OVER THE NEXT
COUPLE DAYS. LATER THIS WEEK...THESE WINDS WILL LIKELY INCREASE
AS THE FRONTAL BOUNDARY PULLS NE AND STRONG HIGH PRES DEVELOPS
TO THE N TIGHTENING THE PRES GRAD.

THE ATLANTIC OCEAN...
WEAK UPPER TROUGHING...VERY DRY AIR ALOFT AND PATCHES OF
LOW-LEVEL MOISTURE UNDERNEATH THE STRONG MID-LEVEL CAP COVERS
THE AREA W OF A PERSISTENT FRONTAL BOUNDARY IN THE CNTRL/WRN
ATLC. THE FRONT IS ASSOCIATED WITH AN OCCLUDED 1012 MB LOW NEAR
33N56W AND IS PROGRESSIVE...COLD FRONT...FROM A TRIPLE POINT NEAR
33N53 SOUTHWESTWARD TO 25N60W THEN STATIONARY TO THE WINDWARD
PASSAGE. MULTILAYERED CLOUDS WITH EMBEDDED SCATTERED SHOWERS ARE
ASSOCIATED WITH THE WEAK LOW/FRONTAL BOUNDARY AND EXTEND WITHIN
300 NM E OF THE FRONT N OF 27N AND WITHIN 150 NM EITHER SIDE S
OF 27N. A SHORTWAVE UPPER TROUGH STRETCHES FROM 32N26W 23N40W TO
AN UPPER LOW IN THE DEEP TROPICS NEAR 9N53W. ELONGATED RIDGING
LIES E OF THE SHORTWAVE AND COVERS THE REMAINDER OF THE E ATLC.
THIS UPPER LEVEL PATTERN IN THE E ATLC HAS SIGNIFICANTLY
FLATTENED TODAY AS THE NRN EXTENSION OF THE SHORTWAVE TROUGH HAS
HELPED TO BREAK DOWN THE ONCE AMPLIFIED UPPER LEVEL RIDGE. AN
UPPER LEVEL HIGH IS LOCATED IN THE TROPICAL ATLC E OF THE UPPER
LOW NEAR 7N37W. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LOW AND
HIGH IS GENERATING ISOLATED SHOWERS FROM 12N-16N BETWEEN
37W-43W...BUT THIS ACTIVITY IS MUCH WEAKER THAN IT HAS BEEN THE
PAST FEW DAYS DUE TO THE FLATTENING PATTERN. PLENTY OF DRY
STABLE AIR ALOFT IS LOCATED E OF 30W ENHANCED BY  UPPER LEVEL
CONFLUENT FLOW W OF AN UPPER TROUGH OVER AFRICA. SWLY UPPER
LEVEL FLOW IS ENHANCING CONVECTION IN THE ITCZ E OF 22W. AT THE
SFC...WEAK TO MODERATE HIGH PRES RIDGING IS THE RULE ACROSS THE
SUBTROPICAL ATLC SUPPORTED BY A 1022 MB HIGH NEAR 29N25W. THIS
RIDGING IS INTERRUPTED BY THE BOUNDARY/FRONTAL LOW MENTIONED IN
THE CNTRL ATLC.

$$
CANGIALOSI



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