[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 290542
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST WED NOV 29 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.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N14W 6N30W 5N44W 4N53W. THE AXIS IS
MORE ACTIVE TODAY THAN THE PAST COUPLE DAYS WITH SCATTERED
MODERATE CONVECTION WITHIN 240 NM N AND 150 NM S OF THE AXIS
BETWEEN 20W-48W. SOME OF THIS ACTIVITY MIGHT BE ASSOCIATED WITH
A TROPICAL WAVE ALONG 40W...THIS WILL BE EXAMINED CLOSER AND IF
NECESSARY WILL BE ADDED TO THE 0600 UTC MAP.

...DISCUSSION...
THE GULF OF MEXICO...
MAINLY FAIR WEATHER CONTINUES ACROSS THE GULF AS SFC HIGH PRES
REMAINS IN CONTROL. BREEZY 15-20 KT ELY WINDS IN THE ERN AND
CNTRL GULF IS ADVECTING PATCHES OF LOW-LEVEL CLOUDS AND EMBEDDED
ISOLATED SHOWERS ACROSS CENTRAL AND SOUTH FLORIDA ON THE BREEZE.
SOME OF THIS LOW-LEVEL MOISTURE IS BEING DRIVEN ACROSS THE GULF
AND TOWARDS THE GULF COAST BY SELY RETURN FLOW AROUND THE 1028
MB SFC HIGH WHICH IS SLIDING E OFFSHORE OF THE MID-ATLANTIC
STATES. IN THE UPPER LEVELS...A STRONG RIDGE IS ALSO SHIFTING E
OF THE AREA...NOW CENTERED OVER SOUTH FLORIDA...IN RESPONSE TO A
SHARP UPPER TROUGH OVER THE WRN U.S. WIDESPREAD STRONG
SUBSIDENCE EXISTS EVERYWHERE ABOVE THE GULF. THIS STRONG CAP IS
PREVENTING THE LOW-LAYER MOISTURE TO ACQUIRE MUCH DEPTH. GFS
SHOWS THE SFC AND UPPER RIDGE CONTINUING ITS EASTWARD MOVEMENT
AS THE UPPER TROUGH APPROACHES. TEMPS WILL REMAIN ABOVE NORMAL
OVER THE NEXT DAY OR TWO BEFORE A COLD FRONT ENTERS THE AREA ON
THU. GALE FORCE WINDS WILL ADVECT A MUCH COLDER AIRMASS INTO THE
WRN AND CNTRL GULF BEHIND THE FRONT. GFS STALLS THE FRONT ON FRI
ACROSS N FLORIDA AND EVENTUALLY A SHORTWAVE GIVES IT A PUSH
ALLOWING IT TO MOVE ACROSS CNTRL AND S FLORIDA LATE THIS
WEEKEND/EARLY NEXT WEEK.

THE CARIBBEAN SEA...
A WELL-DEFINED HIGHLY ELONGATED UPPER LEVEL TROUGH STRETCHES
ACROSS PUERTO RICO SOUTHWESTWARD TOWARDS THE SOUTH AMERICAN
COAST NEAR 15N76W. THE ASSOCIATED COLD FRONT HAS PULLED NE OF
THE AREA. MULTILAYERED CLOUDINESS AND ISOLATED SHOWERS ARE
LOCATED E OF THE UPPER TROUGH AXIS...MAINLY E OF 66W...WHICH
INCLUDES THE LESSER ANTILLES. LOW-LEVEL CLOUDS AND ISOLATED
SHOWERS EXIST ACROSS PUERTO RICO...AS DEPICTED ON SAN JUAN'S
88-D...AND LIKELY HISPANIOLA AND CUBA AS MODERATE NELY LOW-LEVEL
FLOW ACROSS THE ATLC WATERS STIRS UP ENOUGH INSTABILITY. HOWEVER
DUE TO THE VERY DRY STABLE UPPER LEVEL AIR ALOFT ACROSS MUCH OF
THE CARIBBEAN ...W OF THE TROUGH AXIS...THE ACTIVITY IS STAYING
SHALLOW. S-SWLY UPPER LEVEL FLOW IS DRAWING SOME MOISTURE FROM
THE ITCZ AND SPARKING SCATTERED SHOWERS AND TSTMS S OF 14N W OF
73W. TRADE WINDS HAVE INCREASED A LITTLE THIS MORNING BUT REMAIN
MODERATE. THESE WINDS WILL CONTINUE TO STRENGTHEN AS THE FRONTAL
BOUNDARY IN THE ATLC PULLS AWAY AND HIGH PRES STRENGTHENS
TIGHTENING THE PRES GRAD.

THE ATLANTIC OCEAN...
MODERATE TO STRONG HIGH PRES BOTH AT THE SFC AND ALOFT COVERS
THE WRN ATLC. VERY DRY AIR ALOFT IS WIDESPREAD W OF 60W
SUPPRESSING ANY DEEP CLOUDINESS. HOWEVER...BELOW THE SINKING
INVERSION MODERATE NE-ELY FLOW IS GENERATING SMALL PATCHES OF
LOW CLOUDS AND ISOLATED SHOWERS ACROSS THE SEA...SIMILAR TO THE
CONDITIONS IN THE GULF AND NW CARIB. THE ONLY LOW PRES FEATURE
IS IN THE CNTRL ATLC WHERE A COLD FRONT EXTENDS FROM AN OCCLUDED
994 MB LOW NEAR 38N37W ALONG 32N42W 24N48W 18N57W. SWLY UPPER
LEVEL FLOW...ON THE E SIDE OF A HIGHLY ELONGATED MID/UPPER LEVEL
TROUGH...AND LOW-LEVEL LIFT NEAR THE SFC BOUNDARY IS PRODUCING
MULTILAYERED CLOUDS WITH EMBEDDED SCATTERED SHOWERS WITHIN 300
NM EITHER SIDE OF THE FRONT. MODELS SHOW THE SFC LOW QUICKLY
RACING TO THE NE WHICH SHOULD HELP TO SLOWLY THIN THE MOISTURE
PLUME IN THIS AREA OVER THE NEXT DAY OR TWO. AN ELONGATED RATHER
HIGH AMPLITUDE MID/UPPER LEVEL RIDGE LIES E OF THE TROUGH AND
COVERS THE AREA E OF 40W N OF 20N. SLIGHT UPPER LEVEL TROUGHING
STILL EXISTS IN THE TROPICAL ATLC PROVIDING A FAVORABLE PATTERN
FOR CONVECTION IN THE ITCZ. DEEP MOISTURE IS VERY LIMITED
OUTSIDE OF THE ITCZ AND FRONTAL BOUNDARY/UPPER TROUGH. PLENTY OF
DRY STABLE AIR ALOFT IS LOCATED E OF 30W S OF 25N ENHANCED BY
UPPER LEVEL CONFLUENT FLOW W OF AN UPPER TROUGH OVER AFRICA. AT
THE SFC...WEAK TO MODERATE HIGH PRES RIDGING IS THE RULE ACROSS
THE ERN AND WRN SUBTROPICAL ATLC SUPPORTED BY A 1030 MB HIGH NE
OF THE AZORES NEAR 40N16W AND A 1028 MB HIGH OFFSHORE OF THE
MID-ATLANTIC U.S. A PRONOUNCED WEAKNESS IN THIS RIDGING LIES IN
THE CNTRL ATLC DUE TO THE SFC LOW AND FRONTAL BOUNDARY
MENTIONED.

$$
CANGIALOSI


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