[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 191157
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SAT NOV 19 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND 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.

...SPECIAL FEATURE...

TROPICAL STORM GAMMA IS CENTERED NEAR 17.1N 86.3W...OR 115 NM
ESE OF BELIZE CITY BELIZE...AT 19/1200 UTC MOVING NNW 5 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED
WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE LATEST NHC
FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
AND THE PUBLIC ADVISORY UNDER HEADERS MIATCPAT2/WTNT32 KNHC FOR
MORE DETAILS. GAMMA IS UNDER THE INFLUENCE OF MODERATE SOUTHERLY
SHEAR WHICH IS DISPLACING MOST OF THE DEEP CONVECTION N OF THE
LOW-LEVEL CENTER. COLD CLOUD TOPS ARE EXPANDING TO THE N AND
NE...BUT MOST OF THIS IS UPPER LEVEL CIRRUS WITH THE STRONGEST
CONVECTION CLOSE TO THE CENTER. SCATTERED MODERATE CONVECTION IS
FROM 16N-21N BETWEEN 83W-87W...MAINLY OVER OPEN WATERS OF THE NW
CARIBBEAN...BUT ISOLATED SHOWERS ARE STILL OCCASIONALLY
AFFECTING THE BAY ISLANDS OF HONDURAS AND THE OFFSHORE CAYS OF
BELIZE AND MEXICO. DEEP TROPICAL MOISTURE WILL SPREAD NEWD
ACROSS W CUBA AND S/CNTRL FLORIDA AHEAD OF A COLD FRONT WHICH IS
EXPECTED TO SPREAD ACROSS THE GULF OF MEXICO SUN AND MON.

...ITCZ...

ITCZ IS CENTERED ALONG 10N10W 4N25W 10N44W 9N53W 11N62W 9N68W.
SCATTERED MODERATE CONVECTION WITHIN 150 NM OF THE AXIS BETWEEN
20W-27W. WIDELY SCATTERED SHOWERS/TSTMS WITHIN 150 NM S OF THE
AXIS BETWEEN 25W-39W. SCATTERED MODERATE WITHIN 200 NM N OF THE
AXIS BETWEEN 37W-47W. WIDELY SCATTERED MODERATE WITHIN 60 NM OF
THE COAST OF GUYANA AND EXTREME NE VENEZUELA. ISOLATED
SHOWERS/TSTMS OVER PANAMA AND WITHIN 75 NM OF THE COAST OF
COLOMBIA.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL TROUGH COVERS MUCH OF THE CONTINENTAL U.S.
AND MEXICO E OF THE ROCKIES WITH THE MAIN AXIS ROUGHLY ALONG
100W. THIS PATTERN IS PRODUCING SWLY FLOW ALOFT OVER THE GULF
REGION...AND IS HELPING TO PULL SOME OF THE UPPER MOISTURE FROM
T.S. GAMMA NEWD ACROSS THE SE GULF TO FLORIDA. ISOLATED SHOWERS
ARE EMBEDDED WITHIN THIS PLUME...LYING WITHIN 90 NM OF A
STATIONARY FRONT EXTENDING FROM THE YUCATAN CHANNEL TO THE NRN
BAHAMAS. OTHERWISE...THE REST OF THE AREA IS UNDER FAIRLY WEAK
TO MODERATE SUBSIDENCE WITH A FEW PATCHES OF UPPER MOISTURE
SNEAKING EWD ACROSS MEXICO. THE HIGH OVER THE MISSISSIPPI VALLEY
HAS SHIFTED QUICKLY NE TO CNTRL NORTH CAROLINA BUT RIDGING STILL
EXTENDS SWD TO THE BAY OF CAMPECHE AND NELY FLOW IS PRODUCING
OVERCAST LOW CLOUDS AND FOG UP TO 70 NM OFF THE MEXICAN COAST
AND PENETRATING INLAND UP TO 230 NM ONTO THE MEXICAN PLATEAU.
BROKEN STRATUS AND STRATOCUMULUS EXTEND ACROSS THE REST OF THE
GULF WATERS DUE TO POST-FRONTAL COOL AIR DESTABILIZING OVER
WATER TEMPS NEAR 80F. A SECOND COLD FRONT IS EXPECTED TO MOVE
OFF THE TEXAS COAST SUN MORNING AND WILL PULL INCREASED TROPICAL
MOISTURE OVER THE E GULF AND FLORIDA...JUST AHEAD OF T.S. GAMMA.

CARIBBEAN...
A LARGE MID/UPPER LEVEL HIGH IS CENTERED OVER THE CNTRL
CARIBBEAN NEAR 15N75W AND ITS CIRCULATION EXTENDS FROM CNTRL
AMERICA EWD PAST THE LESSER ANTILLES INTO THE ATLC. A PLUME OF
TROPICAL MOISTURE LIES ON THE WRN PERIPHERY OF THE HIGH...
EXTENDING FROM PANAMA/COSTA RICA INTO THE NW CARIBBEAN THEN NEWD
ACROSS CUBA. T.S. GAMMA LIES BENEATH THIS PLUME AND IS PRODUCING
STRONG CONVECTION OVER THE GULF OF HONDURAS. SEE SPECIAL
FEATURES FOR FURTHER DISCUSSION. ELSEWHERE...THE MID/UPPER HIGH
IS PRODUCING STRONG SUBSIDENCE E OF 80W WITH VERY QUIET WEATHER
IN CONTROL FROM JAMAICA EWD TO THE LESSER ANTILLES. A FEW PATCHY
SHOWERS ARE LOCATED NEAR THE N COAST OF THE DOMINICAN REPUBLIC
AND PASSING BY THE ABC ISLANDS BUT THIS IS MORE AN EXCEPTION
THAN THE RULE.

ATLANTIC...
A 90 KT UPPER LEVEL JET EXTENDS FROM THE OUTFLOW OF T.S. GAMMA
NEWD ACROSS S/CNTRL FLORIDA THEN TO NEAR BERMUDA...PARTIALLY
MERGING WITH THE POLAR JET OFF THE U.S. EAST COAST. A STATIONARY
FRONT EXTENDS FROM NEAR HAVANA CUBA NEWD ACROSS THE NRN BAHAMAS
TO 32N66W AND IS PRODUCING ISOLATED SHOWERS WITHIN 150 NM OF THE
BOUNDARY...INCLUDING SPREADING OVER THE N/CNTRL BAHAMAS. FARTHER
E...A COMPLEX UPPER LEVEL LOW IS CENTERED NEAR 27N52W WITH A
TROUGH EXTENDING SW TO BARBADOS AND HAS INDUCED A 1008 MB
SURFACE LOW NEAR 25N59W. IT APPEARS THAT ANOTHER LOW MAY BE
TRYING TO DEVELOP NEAR 31N53W...WHICH THE GFS FORECASTS TO
HAPPEN WITHIN THE NEXT 12-18 HRS. BROAD DIFFLUENCE LIES E OF THE
UPPER TROUGH AXIS AND IS PRODUCING A LARGE AREA OF WIDELY
SCATTERED MODERATE CONVECTION N OF 10N BETWEEN
40W-50W...COVERING MOST OF THE CNTRL ATLC WATERS. SURFACE HIGH
PRES HAS BUILT OVER THE E ATLC ALTHOUGH A WEAK COLD FRONT LIES
ALONG 32N12W 29N20W 28N26W...APPROACHING THE CANARY ISLANDS.
THIS FRONT IS BEING FORCED BY A LARGE DEEP-LAYERED LOW NE OF THE
AZORES WITH THE CIRCULATION STRETCHING SWD TO 20N.

$$
BERG



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