[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 252333
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 25 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 2315 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 47W S OF 19N MOVING W NEAR 15 KT OVER
THE PAST 24 HOURS. THIS WAVE HAS BECOME BETTER ORGANIZED TODAY
WITH A LARGE ENVELOPE OF CYCLONIC TURNING EVIDENT IN THE LOW
AND MID LEVEL CLOUDS AND APPARENT IN SFC OBSERVATIONS. A 1011 MB
LOW IS ALONG THE WAVE NEAR 12N...HOWEVER THE LOW LEVEL
CIRCULATION IS NOT EASILY IDENTIFIABLE IN SATELLITE IMAGES.
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF
THE AXIS S OF 16N. THE WAVE IS CURRENTLY BENEATH AN UPPER
ANTICYCLONE WHICH LIKELY ALLOWED THIS FEATURE TO BECOME BETTER
ORGANIZED TODAY...HOWEVER SIGNIFICANT DEVELOPMENT IS NOT
EXPECTED.

A SFC TROUGH IS ANALYZED ALONG 13N55W 20N57W. SFC OBSERVATIONS
HELPED CONSIDERABLY IN DEFINING THIS AXIS. A 3 DAY SATELLITE
ANIMATION AND 850 MB RELATIVE VORTICITY ANALYSIS FROM UW-CIMSS
SUGGESTS THAT THIS FEATURE MAY BE A TROPICAL WAVE...HOWEVER
BECAUSE MUCH OF ITS ENERGY IS NOW MOVING NW AND DUE TO THE
FEATURE LOSING SOME IDENTITY IT REMAINS ANALYZED AS A TROF.
CONVECTION HAS BEEN ON THE DECREASE OVER THE LAST SEVERAL HOURS
AND CURRENTLY ISOLATED MODERATE WITHIN 240 NM EITHER SIDE OF
THE TROUGH AXIS.

A TROPICAL WAVE IS IN THE ERN CARIBBEAN ALONG 63W S OF 20N
MOVING W NEAR 10 KT. SLIGHT LOW AND MID LEVEL CYCLONIC TURNING
IS EVIDENT WITH A HINT OF A WEAK INVERTED V SIGNATURE. THE WAVE
IS EMBEDDED IN A DRY STABLE ENVIRONMENT. ONLY ISOLATED SHOWERS
ARE WITHIN 120 NM OF THE AXIS.

A LOW AMPLITUDE TROPICAL WAVE IS ALONG 76W S OF 16N DRIFTING W
AS IT REMAINS IN AN AREA OF WEAK STEERING. THIS WAVE WAS
RELOCATED EARLIER TODAY DUE TO SOME ROTATION IN THE
CLOUDS...WHICH BECAME MORE EVIDENT...ABOUT THE ANALYZED
AXIS. SHOWER ACTIVITY IS MINIMAL AND LIKELY ASSOCIATED WITH THE
ITCZ AND THE UPPER TROUGH TO ITS W.

 ...THE ITCZ...
ITCZ AXIS IS ALONG 8N14W 5N30W 12N46W 11N53W 14N60W. BESIDES FOR
THE CONVECTION OUTLINED IN THE TROPICAL WAVES SECTION...ISOLATED
MODERATE IS WITHIN 300 NM N AND 240 NM S OF THE AXIS BETWEEN
29W-41W.

...DISCUSSION...
THE GULF OF MEXICO...
FAIR WEATHER CONTINUES ACROSS THE MAJORITY OF THE GULF SUPPORTED
BY A SFC HIGH PRES RIDGE CENTERED ACROSS THE SE U.S. AND
MODERATELY DRY AIR ALOFT. SFC WINDS ARE FLOWING ANTICYCLONICALLY
AROUND THE RIDGE AND ARE GENERALLY FROM THE E IN THE ERN GULF
TURNING SE-S IN THE WRN GULF. SEVERAL BUOYS IN THE WRN GULF ARE
REPORTING WINDS NEAR 20 KT. THE ONLY AREA OF ANY ACTIVITY IS IN
THE SW GULF WHERE SCATTERED SHOWERS AND ISOLATED TSTMS ARE FROM
19N-24N BETWEEN 93W-96W. THIS IS ASSOCIATED WITH RETURN FLOW
MOISTURE AND A WEAK SFC TROUGH WHICH BROKE OFF FROM THE LARGE
FRONT IN THE ATLC AND CARIB. THE SFC RIDGE IS EXPECTED TO SLIDE
EASTWARD AS A COLD FRONT PUSHES OFF THE TEXAS COAST EARLY FRI.
GFS SUGGESTS THAT THIS FRONT WILL BE QUITE STRONG...BUT NOT AS
STRONG AS THE PREVIOUS ONE...POSSIBLY CLEARING THE ENTIRE AREA
LATE THIS WEEKEND...BRINGING AN INCREASE IN WINDS AND SEAS
BEHIND IT.

THE CARIBBEAN SEA...
THE TAIL END OF THE ATLC FRONTAL BOUNDARY EXTENDS FROM ERN CUBA
TO NRN BELIZE. SCATTERED SHOWERS AND TSTMS ARE WITHIN 90 NM
EITHER SIDE OF THE STATIONARY FRONT. SOME TROPICAL MOISTURE IS
BEING ADVECTED NWD BETWEEN 77W AND 82W BY S-SWLY FLOW BETWEEN
THE UPPER TROUGH MENTIONED AND A UPPER HIGH CENTERED NEAR
13N77W. SCATTERED MODERATE CONVECTION HAS BLOSSOMED THIS EVENING
ACROSS HISPANIOLA INFLUENCED BY THE MOIST SWLY FLOW AND SOME
LOW-LEVEL CONVERGENCE AHEAD OF THE COLD FRONT...AS WELL AS LOCAL
TOPOGRAPHIC LIFT. OTHERWISE...THE CENTRAL AND ERN CARIB IS QUIET
WITH PLENTY OF DRY STABLE AIR ALOFT GENERATED BY AN UPPER HIGH
OVER THE LEEWARD ISLANDS. A TROPICAL WAVE IS CURRENTLY EMBEDDED
IN THIS STABLE ENVIRONMENT SQUEEZING OUT A SMALL AREA OF
SCATTERED SHOWERS ACROSS THE NRN LESSER ANTILLES.

THE ATLANTIC OCEAN...
A STRONG COLD FRONT HAS PUSHED ACROSS MUCH OF THE WRN ATLC AND
IS NOW ANALYZED ALONG 32N53W 23N65W ACROSS THE SE BAHAMAS. COLD
AIR STRATOCUMULUS CLOUDS...STRONG WLY UPPER WINDS AND DRY AIR
ALOFT ARE WIDESPREAD ACROSS THE OCEAN BEHIND THE BOUNDARY.
SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM E OF THE FRONT. AN
AMPLIFIED RIDGING PATTERN EXISTS IN THE CENTRAL ATLC FROM AN
ANTICYCLONE IN THE TROPICAL ATLC NEAR 14N48W TO THE MAIN
SUBTROPICAL ANTICYCLONE NEAR 27N38W. THIS HIGH PRES IS ALSO
ANALYZED AT THE SFC WITH A 1020 MB HIGH NEAR 29N35W AND A 1019
MB HIGH NEAR 23N40W. NLY FLOW ON THE E SIDE OF THIS SFC RIDGE IS
PRESSING THE ITCZ FAR S IN THE E ATLC. A WEAK UPPER LOW...E OF
THE WRN ATLC TROUGH AND W OF THE SUBTROPICAL RIDGE IS ERODING
THE WRN EDGE OF THE AMPLIFIED RIDGE. SCATTERED SHOWERS AND TSTMS
ARE MAINLY S OF 18N BETWEEN 42W AND 60W ASSOCIATED WITH THE
TROPICAL WAVES. VERY DRY AIR IS ASSOCIATED WITH THE MAIN
ANTICYCLONE BETWEEN 30W-45W. THE LARGE STRONG TROUGH THAT HAS
BEEN IN THE E ATLC OVER THE PAST COUPLE OF DAYS IS PULLING E OF
THE AREA EXCEPT FOR AN UPPER LOW WHICH CUT OFF FROM THE TROUGH
AND IS MOVING W CENTERED NEAR 15N30W. MOISTURE ASSOCIATED WITH
THIS UPPER LOW IS MINIMAL. IN FACT...NEARLY ALL OF THE SHOWER
ACTIVITY IN THE E/CENTRAL ATLC IS CONFINED TO THE ITCZ AND
TROPICAL WAVES.

$$
CANGIALOSI




This weather bulletin was brought to you by:
www.nashvilleweather.net