[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111127
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SAT NOV 11 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
1115 UTC.

...TROPICAL WAVES...
TROPICAL WAVE HAS BEEN RELOCATED TO THE E ALONG 55W S OF 14N
MOVING W NEAR 15 KT. THE AXIS WAS ADJUSTED BASED ON A WEAK
INVERTED V-SIGNATURE SEEN IN THE LOW-LEVEL CLOUDS. THIS WAVE HAS
SIGNIFICANTLY WEAKENED OVER THE LAST DAY OR TWO AS MODERATE TO
STRONG SW-WLY WINDS IN COMBINATION WITH STRONG SUBSIDENCE HAS
TAKEN ITS TOLL ON THIS ONCE ACTIVE TROPICAL WAVE. NO DEEP
CONVECTION OR ORGANIZED CLOUDINESS IS ASSOCIATED WITH THIS
FEATURE.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N12W 6N34W 8N50W 10N57W 9N63W. THE
ITCZ AXIS APPEARS UNUSUALLY QUIET WITH ONLY ISOLATED SHOWERS AND
TSTMS WITHIN 240 NM N OF THE AXIS BETWEEN 26W-49W.

...DISCUSSION...
GULF OF MEXICO...
SOUTHWESTERLY UPPER LEVEL FLOW HAS BECOME MORE UNIFORM ACROSS
THE GULF AS THE UPPER RIDGE HAS SHIFTED E...NOW CENTERED ABOVE
THE BAHAMAS AND THE ERN SEABOARD...AND A SHORTWAVE TROUGH
CONTINUES TO DIG IN THE NW GULF. THE ASSOCIATED SFC FRONT HAS
NOW MOVED OFF THE GULF COAST AND AS OF 09Z EXTENDS FROM CENTRAL
LOUISIANA TO EXTREME SRN TEXAS. THIS FRONT IS ACCOMPANIED BY A
NARROW LINE OF SCATTERED SHOWERS AND TSTMS. BUOYS IN THE NW GULF
HAVE MADE SHARP WIND SHIFTS FROM LIGHT SLY TO NLY AND HAVE
INCREASED TO 20-25 KT OVER THE PAST FEW HOURS AS STRONG HIGH
PRES BUILDS SWD OVER THE CNTRL U.S. THE BROAD SWLY UPPER LEVEL
FLOW IS ADVECTING DEBRIS MOISTURE FROM A FEW TROPICAL LOWS IN
THE EPAC...ONE OF WHICH IS THE NEWLY FORMED T.D. 20-E...ACROSS
S/CNTRL MEXICO AND THE GULF MAINLY S OF 27N. THIS MOISTURE IS
NOT A BIG WEATHER FACTOR AS IT IS MAINLY UPPER LEVEL WITH THE
88-D'S ONLY SHOWING A FEW SHOWERS OFF THE COAST OF SW FLORIDA
AND SOME ENHANCED SHOWER ACTIVITY S OF THE COLD FRONT IN NRN
MEXICO. THE SFC HIGH HAS ALSO SHIFTED NE OF THE AREA BUT
CONTINUES TO KEEP LIGHT SE/S WINDS ACROSS THE E AND MID GULF.
THIS FLOW TURNS SWLY IN THE N CNTRL GULF JUST AHEAD OF THE
APPROACHING FRONT. THE FRONT WILL CONTINUE TO MOVE SE THRU THE
DAY TODAY BEFORE SLOWLY BECOMING DIFFUSE AND STATIONARY ON SUN.
NLY WINDS WILL INCREASE BEHIND THE WEAK/MODERATE FRONT...BUT ARE
FORECAST TO STAY WELL BELOW GALE CRITERIA.

CARIBBEAN...
THE CARIB REMAINS QUIET THIS MORNING WITH PLENTY OF DRY/STABLE
SINKING AIR ALOFT IN PLACE. THE MID-UPPER LEVEL PATTERN
PRODUCING THIS STABLE ENVIRONMENT CONSISTS OF AN UPPER RIDGE
CENTERED IN THE NW CARIB NEAR 18N84W AND ANOTHER STRONG UPPER
HIGH LOCATED E OF THE AREA. A WEAKNESS LIES ABOVE THE CNTRL
CARIB INDUCED BY AN UPPER TROUGH TO THE N/NE. THE WEAK LOW PRES
SYSTEM THAT HAS BEEN N OF PANAMA FOR THE PAST 36-48 HOURS HAS
DISSIPATING...HOWEVER THERE ARE STILL SOME LEFT OVER SCATTERED
SHOWERS MOVING ACROSS NICARAGUA. BROKEN PATCHES OF UPPER LEVEL
MOISTURE IS IMPINGING ON THE SRN WINDWARD ISLANDS ASSOCIATED
WITH A TROPICAL JET AND THE REMNANT MOISTURE OF A TROPICAL WAVE.
HOWEVER...THE UPPER ATMOSPHERE IS SO DRY THAT MOST OF THIS IS
QUICKLY BREAKING UP. LITTLE CHANGE IS EXPECTED THRU THE WEEKEND
AS DRY AIR REMAINS ESTABLISHED ACROSS THE AREA. TRADE WINDS ARE
MODERATE AND WILL LIKELY REMAIN THAT WAY OVER THE NEXT COUPLE
DAYS.

ATLANTIC OCEAN...
A SHORT WAVELENGTH RIDGE/TROUGH/RIDGE/TROUGH/RIDGE MID-UPPER
LEVEL PATTERN IS ESTABLISHED ACROSS THE SUBTROPICAL ATLC. VERY
DRY AND STABLE AIR ASSOCIATED WITH THE FIRST OF THESE RIDGES IS
OVER THE SW NORTH ATLC...INCLUDING THE BAHAMAS. A NARROW UPPER
TROUGH EXTENDING S ALONG 53W HAS AN ASSOCIATED SFC COLD FRONT
ALONG 32N53W 23N62W TO NEAR THE N COAST OF THE DOMINICAN
REPUBLIC. A PRE-FRONTAL TROUGH LIES ABOUT 120 NM AHEAD OF THE
FRONT N OF 24N. ONLY LOW AND MID LEVEL CLOUDS AND ISOLATED
SHOWERS ARE ALONG THE FRONT AND TROUGH IN THE DISCUSSION AREA.
MORE CONCENTRATED SHOWER ACTIVITY IS ALONG THE BOUNDARY N OF
32N. THE UPPER TROUGH IS SHOWING SINGS OF CUTTING OFF...AS
SUGGESTED BY GFS...WHICH WILL LIKELY LEAD TO A WEAKENING OF THE
SFC FRONT. A HIGH AMPLITUDE NARROW DEEP-LAYER RIDGE LIES ACROSS
THE CNTRL ATLC BETWEEN 40W-50W. E OF THE RIDGE...THE PATTERN IS
DOMINATED BY A LARGE CUT OFF UPPER LOW CENTERED NEAR 31N30W.
THIS UPPER FEATURE HAS A RELATED SFC LOW WHICH IS ANALYZED AT
1006 MB JUST E OF THE UPPER-LEVEL CENTER. MOST OF THE WEATHER IS
E OF THE SFC LOW...WHERE SCATTERED MODERATE CONVECTION EXISTS N
OF 28N BETWEEN 23W-26W...LINED ALONG A SFC TROUGH. MODELS SHOW
THIS LARGE E OF THIS LARGE LOW...LIES A WEAK RIDGE ALONG 16W. IN
THE DEEP TROPICS...THE MAIN FEATURE IS A WELL-DEFINED UPPER
LEVEL JET STREAM WHICH ORIGINATES NEAR VENEZUELA AND RACES ENE
ALONG 15N56W 16N32W THEN NORTHEASTWARD ALL THE WAY TO THE COAST
OF N AFRICA NEAR 21N17W. HIGHLY SHEARED SCATTERED SHOWERS AND
TSTMS ARE WITHIN 240 NM S OF THE JET AXIS. UPPER CONFLUENCE W OF
THE AXIS IS ENHANCING STRONG SUBSIDENCE.

$$
CANGIALOSI



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