[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 220554
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN OCT 22 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 46W S OF 22N MOVING W NEAR 10 KT. A
1012 MB LOW IS ALONG THE WAVE NEAR 14N. THIS WEAK SWIRL OF LOW
LEVEL CLOUDS APPEARS TO HAVE OPENED UP AND WILL LIKELY BE
REMOVED FROM THE MAP AT 06 Z. ASSOCIATED CONVECTION IS MINIMAL
AND MAINLY WITHIN 360 NM E OF THE WAVE AXIS. THE GLOBAL
MODELS...THAT HAVE THIS WAVE INITIALIZED...CONTINUE TO TRACK IT
WNW AS AN OPEN WAVE.

THE WEAK TROPICAL WAVE THAT WAS PREVIOUSLY ANALYZED NEAR THE
LESSER ANTILLES HAS BEEN REMOVED FROM THE SFC ANALYSIS BECAUSE
OF THE LACK EVIDENCE OF THIS FEATURE OVER THE PAST SEVERAL DAYS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N17W 6N30W 6N44W 7N58W. THE ERN
PORTION OF THE AXIS IS ACTIVE WITH SCATTERED MODERATE CONVECTION
E OF 17W FROM 6N-10N...WITHIN 240 NM N AND 120 NM S OF THE AXIS
BETWEEN 21W-31W AND WITHIN 360 NM N OF THE AXIS BETWEEN 37W-44W.

...DISCUSSION...
THE GULF OF MEXICO...
QUIET WEATHER EXISTS ACROSS MUCH OF THE GULF OF MEXICO THIS
EARLY MORNING THANKS TO DRY STABLE AIR ALOFT IN PLACE GENERATED
BY AN ELONGATED UPPER RIDGE STRETCHED ACROSS THE AREA
ORIGINATING FROM A HIGH CENTER IN THE SW GULF. A WEAK SFC
FRONTAL BOUNDARY IS STATIONARY FROM CENTRAL FLORIDA TO 28N85W
THEN LIFTING N AS A WARM FRONT TO THE MS/AL COASTLINE. SFC FLOW
IS GENERALLY LIGHT FROM THE SE TO S PRODUCING TYPICAL EARLY FALL
WARM AND HUMID CONDITIONS. HOWEVER A CHANGE IN AIRMASS IS IN
STORE FOR THE AREA AS A STRONG COLD FRONT IS CURRENTLY MOVING
OFF THE SE TEXAS COASTLINE. TEMPS HAVE FALLEN TO THE 40'S AND
50'S BEHIND THE BOUNDARY IN TEXAS WITH DEWPOINTS IN THE 30'S. A
LINE OF SHOWERS AND TSTMS HAVE FORMED ALONG A PRE-FRONTAL TROUGH
ANALYZED FROM THE SRN LOUISIANA TO 26N95W. THIS FRONTAL BOUNDARY
WILL LIKELY CLEAR THE ENTIRE AREA LATE MON BRINGING MODIFIED
COOLER AND MUCH DRIER AIR WITH IT. AN INCREASE IN NLY WINDS AND
SEAS WILL FOLLOW THE BOUNDARY AS HIGH PRES BUILDS IN BEHIND THE
FRONT.

THE CARIBBEAN SEA...
THE WEATHER IN THE CARIBBEAN HAS BECOME LESS ACTIVE THIS MORNING
COMPARED TO THE PAST COUPLE OF DAYS. ONLY ISOLATED SHOWERS AND
TSTMS ARE EMBEDDED IN A LARGE UPPER LEVEL MOISTURE PLUME E OF
72W. THIS MOISTURE IS MAINLY ASSOCIATED WITH DEBRIS TROPICAL
MOISTURE ROTATING AROUND AN ANTICYCLONE CENTERED OVER THE
LEEWARD ISLANDS. MORE IMPRESSIVE CONVECTION IS ON THE N SIDE OF
THE RIDGE ASSOCIATED WITH A SFC LOW LOCATED ABOUT 300 NM NNE OF
PUERTO RICO. THE CENTRAL AND WRN CARIBBEAN REMAIN QUIET WITH
ONLY WIDELY SCATTERED SHOWERS. HOWEVER THE ATMOSPHERE ALOFT IS
NOT AS STABLE AS IT WAS OVER THE PAST FEW DAYS DUE TO AN UPPER
LOW...WHICH IS MOISTENING THE AIR SLIGHTLY...TRACKING WWD NOW
CENTERED NEAR JAMAICA. A WEAK SFC TROUGH IS ANALYZED FROM HAITI
SW TO NEAR THE NICARAGUA COAST. SFC WINDS ARE LIGHT AND VARIABLE
NEAR THE TROUGH BUT APPEAR TO BE MORE TYPICAL EASTERLY
ELSEWHERE. THESE WINDS ARE EXPECTED TO BECOME MORE UNIFORM FROM
THE E AND INCREASE SLIGHTLY OVER THE NEXT DAY OR TWO.

THE ATLANTIC OCEAN...
IN THE WRN ATLC...AN UPPER HIGH IN THE SW GULF OF MEXICO HAS
RIDGING THAT EXTENDS NE ACROSS THE NRN BAHAMAS. ANOTHER UPPER
LEVEL RIDGE IS CENTERED OVER THE ERN CARIBBEAN AND CENTRAL ATLC
WITH TWO HIGH CENTERS ONE NEAR 29N50W...WHICH IS GETTING PUSHED
QUICKLY E...AND THE OTHER NEARLY STATIONARY OVER THE LEEWARD
ISLANDS. A SLIGHT WEAKNESS IN THE RIDGE EXISTS OVER THE SRN
BAHAMAS DUE TO THE UPPER LOW IN THE WRN CARIBBEAN. THIS PATTERN
HAS PRODUCED PLENTY OF VERY DRY STABLE AIR N OF 25N W OF 45W.

A THINNING MOISTURE PLUME EXISTS S OF 25N BETWEEN 55W AND 70W.
MOST OF THE MOISTURE IN THIS REGION IS NOT DEEP IN NATURE EXCEPT
FOR ONE CLUSTER OF CONVECTION THAT HAS BEEN INCREASING IN
INTENSITY AND COVERAGE OVER THE PAST FEW HOURS FROM 21N TO 25N
BETWEEN 61W AND 65W. CLOSER ANALYSIS IN THE REGION SUGGESTS THAT
A SFC LOW PRES SYSTEM HAS FORMED NEAR 24N65W WITH A TROUGH
EXTENDING FROM THIS LOW TO HAITI. THE SFC LOW IS EXPOSED LOCATED
ABOUT 40-60 NM W OF THE EDGE OF THE DEEP CONVECTION. WLY UPPER
LEVEL WINDS...ON THE N PERIPHERY OF THE ANTICYCLONE OVER THE
LEEWARD ISLANDS...IS PROVIDING UNFAVORABLE CONDITIONS FOR THE
CONVECTION TO WRAP AROUND THE SFC LOW. THE UPPER LEVEL
ENVIRONMENT MAY BECOME SLIGHTLY LESS HOSTILE OVER THE NEXT DAY
OR SO BEFORE BECOMING VERY UNFAVORABLE AS A LARGE TROUGH MOVES
OFF THE U.S. COAST.

THE TROPICAL ERN ATLC IS DOMINATED BY UPPER RIDGING WITH AN
ANTICYCLONE CENTERED A COUPLE HUNDRED NM SSW OF THE CAPE VERDE
ISLANDS. AN ELONGATED TROUGH STRETCHES FROM THE CANARY ISLANDS
WSW ALONG 27N29W TO A DEVELOPING CUT OFF NEAR 24N35W. THE E ATLC
SFC PATTERN IS DOMINATED BY E-W RIDGING IN THE SUBTROPICS
FROM A 1020 MB NEAR 27N53W TO A 1020 MB HIGH NEAR 25N32W TO A
1017 MB HIGH OVER MOROCCO. THIS RIDGE IS BLEMISHED BY A BENIGN
SFC TROUGH ALONG 32N40W 26N43W.

$$
CANGIALOSI




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