[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211052
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT OCT 21 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 1045 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 43W S OF 21N MOVING W 10 TO 15 KT. A
1010 MB LOW IS ALONG THE WAVE NEAR 14N. THIS LOW PRES AREA
REMAINS A LOW LEVEL CLOUD SWIRL WELL REMOVED FROM THE ASSOCIATED
CONVECTION WHICH IS A FEW HUNDRED NM TO ITS E. A CLUSTER OF
SCATTERED MODERATE CONVECTION HAS INCREASED IN INTENSITY AND
COVERAGE THIS MORNING FROM 14N-18N BETWEEN 36W-39W. HOWEVER...
THIS CONVECTION IS HAVING A TOUGH TIME ROTATING AROUND THE SFC
LOW AS STRONG W-SW WINDS KEEPING SHEARING IT OFF. ISOLATED
MODERATE CONVECTION ALSO EXISTS ELSEWHERE WITHIN 300 NM
EITHER SIDE OF THE WAVE AXIS.

A WEAK TROPICAL WAVE IS ALONG 56W S OF 16N MOVING W 10 TO 15 KT.
THIS WAVE DOES NOT EXHIBIT ANY SIGNATURE ON SATELLITE IMAGERY OR
IN AVAILABLE SFC DATA...THEREFORE THE PSN IS BASED ON
CONTINUITY. THIS FEATURE WILL LIKELY BECOME ABSORBED INTO THE
BROAD TROUGH IN THE CARIBBEAN.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 7N25W 9N35W 11N45W 12N60W.
THE ERN PORTION OF THE AXIS HAS BECOME A LITTLE MORE ACTIVE...
SCATTERED MODERATE CONVECTION IS WITHIN 300 NM S AND WITHIN 180
NM N OF THE AXIS E OF 25W. SIMILAR CONVECTION IS FROM 7N-12N
BETWEEN 33W-37W. CLUSTERS OF SCATTERED MODERATE IS ACROSS N
VENEZUELA AND INTO THE S CARIBBEAN FROM 7N-15N BETWEEN 62W-66W.

...DISCUSSION...
THE GULF OF MEXICO...
A WEAKENING SHORTWAVE TROUGH ACROSS THE NRN PORTION OF THE AREA
HAS FLATTENED WITH UPPER LEVEL FLOW BECOMING MORE ZONAL ACROSS
THE SRN U.S. AND NRN GULF. THIS HAS MADE THE ASSOCIATED FRONTAL
BOUNDARY STATIONARY WITH THE WRN END LIFTING BACK N AS A WARM
FRONT. AS OF 09 UTC...THE FRONT WAS ANALYZED AS STATIONARY FROM
NEAR DAYTONA BEACH TO 27N88W THEN AS A WARM FRONT TO THE SRN
TEXAS COAST. A LINGERING STATIONARY FRONT REMAINS ALONG THE E
SLOPES OF THE SIERRA MADRE MOUNTAINS IN MEXICO. ONLY ISOLATED
SHOWERS ARE FOUND WITHIN 150 NM N OF THE BOUNDARY. TRANQUIL
WEATHER CONTINUES ACROSS THE SRN PORTION OF THE GULF...THANKS TO
DRY STABLE AIR ALOFT IN PLACE GENERATED BY A HIGHLY NE-SW
ELONGATED MID/UPPER RIDGE. THE SFC FRONT IS EXPECTED TO CONTINUE
TO LIFT NWD THROUGHOUT THE DAY BEFORE THE NEXT COLD
FRONT...CURRENTLY DRAPED ACROSS THE CNTRL U.S....PUSHES OFF THE
GULF COAST EARLY SUN. GFS ANTICIPATES THIS SECOND FRONT TO DIG
MUCH FURTHER S POSSIBLY CLEARING THE ENTIRE AREA BY LATE
MON...BRINGING COOLER/DRIER AIR AND AN INCREASE IN NLY WINDS AND
SEAS BEHIND IT.

THE CARIBBEAN SEA...
SOME UNSETTLED WEATHER IS STILL OCCURRING IN THE ERN CARIBBEAN
DUE TO A SLOW MOVING PERSISTENT DEEP LAYER TROUGH. THE BROAD
AREA OF LOW PRES THAT WE HAVE BEEN ANALYZING APPEARS TO HAVE
DISSIPATED AS THERE IS NO EVIDENCE OF ANY CLOSED SFC
CIRCULATION. A SFC TROUGH EXTENDS FROM HAITI SOUTHWESTWARD ALONG
16N73W 12N75W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN
150 NM EITHER SIDE OF THE TROUGH AXIS. MORE IMPRESSIVE RAINFALL
IS OCCURRING FARTHER E ASSOCIATED WITH THE MOIST SWLY FLOW ON
THE E SIDE OF THE MID/UPPER TROUGH DRAWING DEEP TROPICAL
MOISTURE NWD. SCATTERED TO NUMEROUS MODERATE CONVECTION IS
MOVING NWD OFF THE NRN S AMERICA COAST S OF 15N BETWEEN 63W-68W.
GFS SHOWS THIS MOISTURE SLOWLY THINNING OUT AND DRIFTING W OVER
THE NEXT FEW DAYS AS THE UPPER TROUGH MOVES W AND A WEAK UPPER
RIDGE BUILDS OVER THE AREA. THE WRN CARIBBEAN REMAINS MAINLY
QUIET WITH VERY DRY AIR ALOFT BEING ADVECTED IN THE REGION FROM
AN ELONGATED UPPER RIDGE TO THE N. THE ATMOSPHERE WILL BE
MOISTENING UP AS THE TROUGH SLIDES W. SFC WINDS ARE LIGHT AND
VARIABLE ACROSS THE CARIBBEAN DUE TO THE PRESENCE OF THE SFC
TROUGH. EASTERLY TRADES WILL LIKELY RESUME LATE SAT/EARLY
SUN.

THE ATLANTIC OCEAN...
A FAIRLY COMPLEX MID/UPPER LEVEL PATTERN EXISTS ACROSS THE ATLC.
IN THE WRN ATLC...AN UPPER HIGH IN THE GULF OF MEXICO HAS
RIDGING THAT EXTENDS NE ACROSS THE NRN BAHAMAS. ANOTHER UPPER
HIGH IS CENTERED E OF BERMUDA NEAR 31N58W. VERY DRY STABLE AIR
IS NOTED N OF 25N GENERATED BY THESE ANTICYCLONES. DEEP LAYER
TROUGHING EXISTS BETWEEN THESE UPPER RIDGES WITH THE SFC
BOUNDARY EXTENDING ALONG 24N63W 21N70W TO HAITI. A LARGE AREA OF
MOISTURE WITH EMBEDDED AREAS OF DEEP CONVECTION EXISTS S OF THE
LARGE ANTICYCLONE NEAR BERMUDA AND E OF THE DEEP LAYER TROUGH IN
THE CNTRL CARIBBEAN...NAMELY S OF 25N BETWEEN 50W AND 70W. THE
DEEPEST BLOB OF CONVECTION IS NE OF PUERTO RICO FROM 20N TO 23N
BETWEEN 61W AND 65W. DEBRIS UPPER LEVEL MOISTURE IS THEN
ADVECTED EASTWARD BY A WLY JET N OF AN UPPER HIGH IN THE
TROPICAL N ATLC...AS WELL AS ANOTHER FARTHER E NEAR 16N46W...AND
S OF AN UPPER LOW NEAR 26N41W. THIS JET HAS CORE WINDS NEAR 80
KT BASED ON UW-CIMSS SATELLITE DERIVED WINDS. THE TROPICAL ERN
ATLC IS DOMINATED BY UPPER RIDGING WITH AN ANTICYCLONE CENTERED
OVER THE CAPE VERDE ISLANDS. THE E ATLC SFC PATTERN IS DOMINATED
BY WEAK E-W RIDGING IN THE SUBTROPICS FROM A 1018 MB NEAR 30N56W
TO A 1019 MB HIGH NEAR 27N31W TO A 1017 MB HIGH OVER THE CANARY
. THIS RIDGE IS BLEMISHED A SFC TROUGH EXTENDING FROM A 1010 MB
ALONG 32N48W 26N54W AND POSSIBLY ANOTHER TROUGH ASSOCIATED WITH
THE UPPER LEVEL LOW NEAR 26N41W.

$$
CANGIALOSI





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