[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 190553
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURE...

TROPICAL STORM GAMMA IS CENTERED NEAR 16.7N 86.1W...OR 135 NM
ESE OF BELIZE CITY BELIZE...AT 19/0600 UTC MOVING NW 4 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 PRODUCING A TIGHT CLUSTER OF NUMEROUS
MODERATE/STRONG CONVECTION OVER THE GULF OF HONDURAS FROM
16N-20N BETWEEN 84W-87W WHICH AT THE MOMENT IS ONLY AFFECTING
THE BAY ISLANDS OF HONDURAS AND OCCASIONALLY THE OFFSHORE CAYS
OF BELIZE AND MEXICO. THE SYSTEM IS EMBEDDED BENEATH A LARGE
SWATH OF SLY MID/UPPER LEVEL FLOW WITH THE SHEAR PULLING THE
CIRRUS OUTFLOW NEWD TOWARDS THE STRAITS OF FLORIDA. GAMMA IS
EXPECTED TO MOVE N/NE TOWARDS THE YUCATAN CHANNEL THEN
FLORIDA...LIKELY MERGING WITH A FRONTAL BOUNDARY WHICH WILL
SPREAD ACROSS THE GULF OF MEXICO SUN AND MON.

...ITCZ...

ITCZ IS CENTERED ALONG 10N14W 8N20W 9N60W. WIDELY SCATTERED
SHOWERS/TSTMS WITHIN 330 NM S OF THE AXIS BETWEEN 21W-38W.
WIDELY SCATTERED MODERATE WITHIN 300 NM OF THE AXIS BETWEEN
35W-55W. ISOLATED SHOWERS/TSTMS OVER SE NICARAGUA AND NRN COSTA
RICA.

...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. A 1028 MB HIGH IS IN CONTROL OVER NW
MISSISSIPPI WITH RIDGING EXTENDING TO THE BAY OF CAMPECHE AND
THE NELY FLOW IS PRODUCING OVERCAST LOW CLOUDS AND FOG UP TO 60
NM OFF THE MEXICAN COAST AND PENETRATING INLAND UP TO 220 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 16N75W 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 32N68W 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 26N53W WITH A
TROUGH EXTENDING SW TO BARBADOS AND HAS INDUCED A 1006 MB
SURFACE LOW NEAR 25N59W. IT APPEARS THAT ANOTHER LOW MAY BE
TRYING TO DEVELOP NEAR 30N52...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-51W...COVERING MOST OF
THE CNTRL ATLC WATERS. SURFACE HIGH PRES HAS BUILT OVER THE E
ATLC ALTHOUGH A WEAK COLD FRONT LIES ALONG 32N14W 29N20W
28N30W...APPROACHING THE CANARY ISLANDS. THIS FRONT IS BEING
FORCED BY A LARGE UPPER LOW NE OF THE AZORES WITH THE
CIRCULATION STRETCHING SWD TO 20N.

$$
BERG


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