[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122350
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN NOV 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...TROPICAL WAVES...
A LOW AMPLITUDE TROPICAL WAVE IS ALONG 61W S OF 14N MOVING W
NEAR 10 KT. THE WAVE APPEARS TO HAVE SLOWED DOWN A BIT AND
REMAINS LESS OBVIOUS THAN IT WAS A FEW DAYS AGO...THOUGH SOME
CYCLONIC TURNING OF THE LOW TO MID CLOUD FIELD STILL EVIDENT
FROM 10N-14N WITHIN 200NM OF THE AXIS. THE CLUSTERS OF SCATTERED
MODERATE CONVECTION THAT DEVELOPED BETWEEN BARBADOS AND TRINIDAD
EARLIER TODAY HAVE DIMINISHED IN BOTH COVERAGE AND INTENSITY
OVER THE LAST SEVERAL HOURS...WITH STRONG WSW SHEAR CONTINUING
OVER THE WAVE.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 5N30W 7N50W 10N60W. SCATTERED
MODERATE CONVECTION IS FROM 4N-11N BETWEEN 20W-36W. SIMILAR
CONVECTION IS FROM 10N-14N BETWEEN 45W-50W...THOUGH THIS MAY BE
MORE ASSOCIATED WITH UPPER DIFFLUENCE.

...DISCUSSION...
GULF OF MEXICO...
NEARLY ZONAL FLOW DOMINATES MOST OF THE GULF N OF AN UPPER HIGH
CENTERED OVER BELIZE. AN UPPER TROUGH EXTENDS S OFF THE SE U.S.
COAST FROM AN UPPER LOW SPINNING OVER DUCK NORTH CAROLINA. AS OF
2100 UTC...THE ASSOCIATED COLD FRONT EXTENDS FROM S CENTRAL FL
TO THE CENTRAL GULF NEAR 25N87W...THEN CONTINUES AS A STATIONARY
FRONT AS IT DRAPES S TO THE ISTHMUS OF TEHUANTEPEC.
HOWEVER...CONFIDENCE ON THE EXACT PLACEMENT OF THIS FRONTAL
BOUNDARY IS LOW WITH ABUNDANT UPPER MOISTURE OVER THE AREA
OBSCURING THE SFC FEATURES...AND THE FRONT BEGINNING TO WASH
OUT. THERE IS A MARKED DEWPOINT GRADIENT THROUGH FLORIDA
THOUGH...WITH VALUES IN THE 40S IN NORTH/CENTRAL FLORIDA AND 60S
IN SE FL. VERY LITTLE DEEP CONVECTION NOTED WITHIN SEVERAL
HUNDRED MILES OF THE FRONT...WITH MUCH OF THE UPPER MOISTURE
OVER THE GULF ATTRIBUTED TO DEBRIS DOWNSTREAM OF THE EPAC
TROUGH/REMNANTS OF ROSA AND T.D. 20-E. SFC HIGH PRESSURE N OF
THE AREA IS TAKING OVER THE GULF AS THE FRONT WASHES OUT. THE
HIGH WILL MOVE SLOWLY E INTO EARLY WEEK WITH GRADUALLY
DECREASING WINDS AND SEAS EXPECTED.

CARIBBEAN...
A BROAD UPPER RIDGE COVERS THE WEST-CENTRAL CARIBBEAN AND
CENTRAL AMERICA FROM AN UPPER HIGH CENTERED OVER BELIZE. AN
UPPER TROUGH OVER THE CENTRAL ATLC DIPS INTO THE E
CARIBBEAN...ENTERING THE REGION JUST SE OF PUERTO RICO TO THE
ABC ISLANDS. ABUNDANT DRY/STABLE AIR ALOFT...RESULTING IN
MODERATE TO STRONG SUBSIDENCE AND FAIR WEATHER...CONTINUES TO
DOMINATE MOST OF THE AREA N OF 12N. UPPER LEVEL MOISTURE IS
SPREADING ACROSS THE NW CORNER OF THE BASIN WHERE THERE IS A
SMALL AREA OF SHOWERS. THIS IS LIKELY ASSOCIATED WITH UPPER
DIFFLUENCE ALONG WITH WEAK LOW LEVEL CONFLUENCE. A 1008 MB
SURFACE LOW LOCATED NEAR 10N81W...ALONG WITH THE ITCZ...IS
GENERATING SCATTERED SHOWERS OVER THE SW CARIBBEAN. 10-20 KT
TRADE WINDS ARE BLOWING ACROSS THE REGION AND WILL PERSIST INTO
EARLY WEEK.

ATLANTIC OCEAN...
SFC COLD FRONT ENTERS THE SW NORTH ATLC ALONG 32N75W AND EXTENDS
SW TO SOUTH CENTRAL FLORIDA. FRONT IS ASSOCIATED WITH PRONOUNCED
UPPER LOW OVER DUCK NORTH CAROLINA...THAT HAS AN UPPER TROUGH
EXTENDING S INTO THE REGION. VERY LITTLE DEEP CONVECTION
ASSOCIATED WITH THE BOUNDARY THOUGH...WITH JUST ISOLATED SHOWERS
EXPECTED WITHIN 150 NM OF THE FRONT. STRONG OFFSHORE FLOW OFF
THE SE US COAST VEERS N ALONG THE FL COAST AND DECREASES FURTHER
S AS THE GRADIENT WEAKENS...SEE MIAOFFNT3 FOR DETAILS. AN UPPER
RIDGE STRETCHES NEWD FROM THE WRN CARIBBEAN ACROSS CUBA AND THE
BAHAMAS TOWARDS BERMUDA. A PAIR OF MID/UPPER CUT-OFF LOWS ARE
ARE AFFECTING THE CENTRAL/ERN ATLC FROM 26N-40N BETWEEN
20W-60W...COVERING THE CENTRAL AND EASTERN ATLC. THE WRN MOST OF
THESE HAS A REFLECTION AT THE SFC AS A 1009MB LOW NEAR
30N51W...WITH A WEAKENING COLD FRONT EXTENDING SW FROM THE LOW
TO NEAR THE VIRGIN ISLANDS. THIS BOUNDARY MARKED BY A LINE OF
LOW TO MID CLOUDS WITH NO DEEP CONVECTION. THE CLOUD PATTERN OF
THIS SYSTEM IS STARTING TO RESEMBLE AN OCCLUSION...THOUGH WITH
VERY LITTLE TEMP GRADIENT IN THE AREA A TROF MAY BE THE
PREFERRED SOLUTION IN FUTURE MAPS. THE LOW IS EXPECTED TO MOVE
LITTLE THROUGH EARLY TO MID WEEK. SUBSTANTIAL ZONAL WLY FLOW
ALOFT DOMINATES MUCH OF THE AREA S OF THESE CUT OFF LOWS...FROM
10N-30N BETWEEN 20W-50W.

$$
MW/GR




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