[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 270002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU OCT 26 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 ADDED TO THE 18 Z ANALYSIS ALONG 35W/36W S OF
13N MOVING W 10 TO 15 KT. SOME LOW TO MID LEVEL CLOUD TURNING IS
APPARENT ON THE LAST FEW VIS IMAGES THIS EVENING EMBEDDED IN A
LARGE MASS OF MOISTURE...ASSOCIATED WITH THE ITCZ AND ENHANCED
BY AN UPPER LOW TO ITS N. DUE TO THE ABUNDANT HIGH LEVEL
MOISTURE IN THE REGION IT IS DIFFICULT TO FIND THE LOCATION OF
THE LOW-LEVEL WAVE AXIS. HOWEVER...THERE IS A FAIR AMOUNT OF
CONFIDENCE IN INTRODUCING THIS WAVE BASED ON A TRACKABLE FEATURE
IN THE MET-9 HOVMOLLER DIAGRAMS AND LOW-LEVEL VORTICITY
ANALYSIS.

A TROPICAL WAVE IS ALONG 52W/53W S OF 20N MOVING W 10 TO 15 KT.
A 1010 MB LOW IS ALONG THE WAVE NEAR 13N. THIS LOW PRES SYSTEM
HAS BECOME BETTER DEFINED WITH THE LOW-LEVEL CENTER NOW FAIRLY
EASY TO LOCATE ON SATELLITE IMAGES. DESPITE THE FAIR STRUCTURE
OF THIS SYSTEM...SHOWERS AND TSTMS REMAIN MINIMAL AND
DISORGANIZED FROM 11N-16N BETWEEN 50W-56W...THEREFORE FURTHER
DEVELOPMENT IS NOT ANTICIPATED AT THIS TIME.

A WEAK TROPICAL WAVE IS ALONG 68W S OF 19N MOVING W 10 TO 15 KT.
CYCLONIC WIND SHIFTS ARE EVIDENT IN THE LOW-LEVELS BASED UPON
SFC OBSERVATIONS...QSCAT AS WELL AS SAT IMAGES. THE WAVE IS
EMBEDDED IN A DRY ENVIRONMENT JUST SE OF THE STRONG ATLC FRONTAL
BOUNDARY...PRODUCING ONLY ISOLATED SHOWERS.

 ...THE ITCZ...
ITCZ AXIS IS ALONG 10N14W 7N26W 6N37W 12N50W. A LARGE AREA OF
ISOLATED MODERATE CONVECTION...PARTLY ASSOCIATED WITH THE
TROPICAL WAVE ALONG 35W/36W...IS FROM 1N-12N BETWEEN 30W-44W.
SCATTERED MODERATE IS WITHIN 90 NM N OF THE AXIS BETWEEN 20W-30W.

...DISCUSSION...
THE GULF OF MEXICO...
MOST OF THE AREA IS SLIGHTLY WARMER AND MORE HUMID TODAY THAN
THE PAST FEW DAYS AS RETURN FLOW HAS BECOME MORE UNIFORMLY
ESTABLISHED ACROSS THE GULF. S AND SE WINDS ARE IN THE 15-20 KT
RANGE ACROSS THE REGION. NEARLY THE ENTIRE GULF OF MEXICO IS
RAIN-FREE...DUE TO SFC HIGH PRES AND MODERATE AIR ALOFT IN
PLACE...EXCEPT FOR SCATTERED SHOWERS AND TSTMS MOVING NWD IN THE
YUCATAN CHANNEL AND NUMEROUS SHOWERS AND TSTMS ACROSS THE U.S.
GULF COAST AND COASTAL WATERS. THE LATTER IS ASSOCIATED WITH THE
NEXT FRONTAL SYSTEM THAT WILL ENTER THE NW PORTION OF THE REGION
LATE TONIGHT OR TOMORROW MORNING. THIS FRONT WILL BRING AN
INCREASE IN MOISTURE AHEAD OF IT AND COOLER/DRIER AIR BEHIND IT.
NLY WINDS WILL INCREASE WITH GUSTS TO GALE FORCE BUILDING HIGH
SEAS AS STRONG SFC RIDGING BUILDS IN BEHIND THE FRONT.

THE CARIBBEAN SEA...
THE TAIL END OF A STRONG ATLC FRONTAL BOUNDARY IS LOSING ITS
IDENTITY IN THE CARIBBEAN AND IS ANALYZED AS A TROUGH AT 21 Z
FROM HISPANIOLA TO THE NE PART OF THE YUCATAN PENINSULA. A
BROKEN LINE OF SCATTERED SHOWERS AND TSTMS ARE WITHIN 120 NM S
OF THE BOUNDARY E OF 78W AND WITHIN 120 NM EITHER SIDE W OF 78W.
THE WRN PORTION OF THIS BOUNDARY IS BEING DRIVEN NWD BY SFC
RETURN FLOW. SCATTERED SHOWERS AND TSTMS ARE ALSO OCCURRING
ACROSS A GOOD PORTION OF CENTRAL AMERICA AND THE SW CARIBBEAN S
OF 16N W OF 80W. THIS ACTIVITY IS ASSOCIATED WITH MOIST SLY
UPPER LEVEL FLOW BETWEEN A WEAKENING SMALL UPPER TROUGH IN THE
NW CARIB AND AN UPPER HIGH CENTERED NEAR 14N78W. THE ERN
CARIBBEAN IS MAINLY DRY WITH MODERATE DRY AIR ALOFT...BUT THE
AIR IS MOISTENED UP SLIGHTLY WITH NLY UPPER LEVEL FLOW SPREADING
SOME MOISTURE INTO THE REGION FROM THE DEEP LAYER TROUGH TO THE
N. SCATTERED SHOWERS EXISTS IN THE LESSER ANTILLES AND ISOLATED
SHOWERS ARE IN THE VICINITY OF THE WEAK TROPICAL WAVE ALONG 68W.
MOISTURE WILL LIKELY BE ON THE INCREASE IN THE ERN CARIB THIS
WEEKEND AS A TROPICAL WAVE AND WEAK AREA OF LOW PRES...CURRENTLY
450 NM E OF THE LESSER ANTILLES...MOVES INTO THE AREA.

THE ATLANTIC OCEAN...
A HIGHLY AMPLIFIED PATTERN IS ESTABLISHED ACROSS THE ATLC. HIGH
PRES RIDGING EXISTS ACROSS THE ERN U.S. AND A PORTION OF THE WRN
ATLC W OF 73W. A LARGE STRONG TROUGH LIES TO THE E OF THE RIDGE.
THE HIGHEST AMPLITUDE OF THE TROUGH IS ASSOCIATED WITH A POLAR
LOW BUT STILL 80-100 KT SW-WLY UPPER LEVEL JET...BASED ON CIMSS
DERIVED WINDS...EXTENDS ACROSS THE N PORTION OF THE DISCUSSION
AREA BETWEEN 45W-73W. AN ASSOCIATED COLD FRONT REMAINS WELL
DEFINED ALONG 32N47W 24N60W TO THE DOMINICAN REPUBLIC. SCATTERED
SHOWERS AND TSTMS ARE WITHIN 180 NM E OF THE FRONT. BEHIND THE
FRONT...A DRIER AND COOLER AIRMASS EXISTS. SEVERAL SHIPS ARE
REPORTING SEAS 8 TO 13 FT IN NLY SWELL. REFER TO MIAHSFAT2 AND
OFFNT3 FOR DETAILS. A LARGE STRONG MID/UPPER LEVEL RIDGE IS
LOCATED E OF THE TROUGH CENTERED IN THE SUBTROPICS NEAR 29N31W.
THIS RIDGE COVERS THE REMAINDER OF THE ATLC E OF 45W WITH DRY
STABLE AIR ALOFT WIDESPREAD IN THE REGION. SFC HIGH PRES IS ALSO
ANALYZED UNDERNEATH THE MID/UPPER RIDGE WITH A 1022 MB HIGH NEAR
32N29W AND A 1018 MB HIGH NEAR 24N40W. SWIFT NLY LOW LEVEL FLOW
ON THE E SIDE OF THE SFC RIDGE IS PRESSING THE ITCZ FAIRLY FAR S
IN THE E ATLC. AN UPPER LOW...WHICH CUT OFF FROM THE STRONG
TROUGH THAT WAS IN THE E ATLC EARLIER THIS WEEK...IS TRACKING W
CENTERED NEAR 16N35W. UPPER DIFFLUENCE ON THE SE SIDE OF THIS
LOW IS GENERATING A LARGE AREA OF HIGH LEVEL MOISTURE IN THE
ITCZ BETWEEN 30W-45W.

$$
CANGIALOSI






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