[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171755
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON NOV 17 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
A LOW AMPLITUDE TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN
ALONG 65W/66W SOUTH OF 17N MOVING SLOWLY WWD. WE HAVE BEEN
FOLLOWING THIS WAVE/TROUGH FOR THE LAST SEVERAL DAYS. AT LEAST
SINCE NOVEMBER THE 13TH...THE HOVMOLLER DIAGRAM HAS BEEN SHOWING
THIS FEATURE TO BE PROPAGATING WWD. THIS WAVE IS ALSO WELL
DEPICTED IN THE MOISTURE PRODUCT AND SFC OBSERVATIONS. THIS
SYSTEM IS GENERATING SCATTERED MODERATE CONVECTION OVER THE SE
CARIBBEAN PARTICULARLY SOUTH OF 15N AND EAST OF 67W. THE SHOWER
ACTIVITY EXTENDS EWD ACROSS THE WINDWARD ISLANDS AND INTO THE
TROPICAL N ATLC. BARBADOS REPORTED A TOTAL OF 2.10 INCHES OF
RAIN FOR THE PAST 24 HOURS.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N13W 6N30W 7N40W 7N50W INTO THE
GUYANAS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
4N-9N BETWEEN 20W-29W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE HIGH PRES WITH A COUPLE OF 1029 MB CENTERS OVER THE
UPPER TEXAS COAST AND NE MEXICO DOMINATES THE ENTIRE REGION AND
THE NORTHERN GULF STATES. THIS FEATURE IS PRODUCING A SUNNY AND
DRY DAY OVER THE SE CONUS INCLUDING THE STATE OF FLORIDA.
NORTHERLY WINDS OF 15 TO 20 KT ARE BLOWING ACROSS THE GULF WITH
THE STRONGEST WINDS OVER THE BAY OF CAMPECHE AND THE SE GULF
INCLUDING THE STRAITS OF FLORIDA. ADDITIONALLY...STRONG N SFC
WINDS ARE ALSO BLOWING THROUGH THE ISTHMUS OF TEHUANTEPEC
RESULTING IN STORM FORCE WINDS IN THE E PACIFIC REGION. BROKEN
TO OVERCAST COLD AIR STRATOCUMULUS CLOUDS ARE NOTED OVER THE
GULF SOUTH OF 27N. THESE CLOUDS ARE MOVING SOUTH REACHING THE
YUCATAN PENINSULA. LOW-LEVEL CLOUDS POOLED AGAINST THE SIERRA
MADRE MOUNTAINS COVER SE MEXICO MAINLY THE STATES OF VERACRUZ
AND TABASCO. SURFACE COLD AIR ADVECTION WILL CONTINUE TO AFFECT
THE AREA AS A REINFORCING COLD FRONT MOVES INTO THE N GULF
WATERS TONIGHT AND TUE FOLLOWED BY AN AREA OF STRONG HIGH PRES.
AS A RESULT...WIND SPEEDS ARE EXPECTED TO INCREASE ACROSS THE
GULF REGION ON TUE BUT MAINLY ACROSS THE EASTERN HALF DUE TO A
TIGHT PRES GRADIENT BETWEEN THIS SFC HIGH PRES AND EXTRATROPICAL
LOW OVER THE W ATLC.

CARIBBEAN SEA...
A STATIONARY FRONT IS OVER THE CARIBBEAN SEA EXTENDING FROM
EASTERN CUBA TO NEAR CABO GRACIAS A DIOS NICARAGUA. THE FRONT IS
GENERATING SCATTERED MODERATE CONVECTION JUST SOUTH OF THE
CAYMAN ISLANDS. THIS SYSTEM IS FORECAST TO REMAIN IN PLACE
THROUGH TUE NIGHT. LOOKING AHEAD...A FAST MOVING COLD FRONT WILL
SWEEP THROUGH THE GULF OF MEXICO AND MERGE WITH THE STATIONARY
FRONT REACHING FROM THE DOMINICAN REPUBLIC TO FAR SW CARIBBEAN
BY WED MORNING. INCREASING NLY WINDS WILL FOLLOW THE REINFORCING
COLD FRONT AS HIGH PRES BUILDS OVER THE NW CARIBBEAN. THE GFS
MODEL SUGGESTS NLY WINDS OF 20 TO 30 KT TUE THROUGH WED. COLD
AIR STRATOCUMULUS CLOUDS FROM THE GULF OF MEXICO ARE INVADING
WESTERN CUBA AND THE NW CARIBBEAN UNDER A NLY WIND FLOW. THESE
WINDS ARE ADVECTING LOW-LEVEL CLOUDS WITH EMBEDDED LIGHT SHOWERS
ACROSS THE GULF OF HONDURAS INTO HONDURAS. A TROPICAL WAVE IS
OVER THE EASTERN CARIBBEAN. SEE TROPICAL WAVE SECTION. A WEAK
1010 MB LOW HAS DEVELOPED OVER THE SW CARIBBEAN NEAR 10.5N80.5W.
VIS SATELLITE IMAGERY REVEALS SOME CYCLONIC TURNING IN THE CLOUD
PATTERN SINCE THIS MORNING. PATCHES OF MOISTURE WITH EMBEDDED
LIGHT SHOWERS ARE MOVING ACROSS PUERTO RICO...THE VIRGIN ISLANDS
AND REGIONAL WATERS. ALOFT...A RIDGE ANCHORED ON A HIGH JUST W
OF JAMAICA IS HELPING TO INDUCE CONVECTION ALONG THE FRONTAL
BOUNDARY AND OVER THE SW CARIBBEAN. AN UPPER-LEVEL TROUGH
EXTENDS FROM HISPANIOLA TO JUST OFFSHORE THE COLOMBIAN COAST
NEAR 12N76W. THE COMBINATION OF THIS TROUGH AND A RIDGE OVER N
SOUTH AMERICA IS PRODUCING UPPER DIFFLUENCE OVER THE SE
CARIBBEAN AND THE WINDWARD ISLANDS ENHANCING CONVECTION DOWN
THERE.

ATLANTIC OCEAN...
A DEEP LAYERED TROUGH OVER THE EASTERN U.S. SUPPORTS A COLD
FRONT THAT CROSSES JUST E OF BERMUDA ENTERING THE FORECAST AREA
NEAR 31N64W. THE FRONT CONTINUES SW ACROSS THE SE BAHAMAS AND
INTO EASTERN CUBA WHERE IT BECOMES STATIONARY. A BAND OF LOW TO
MID CLOUDS WITH SCATTERED SHOWERS IS RELATED TO THE FRONT OVER
THE ATLC OCEAN. A SURFACE RIDGE CENTERED ON A 1022 MB HIGH NEAR
34N54W COVERS THE CENTRAL ATLANTIC. FARTHER EAST...THERE IS A
SFC TROUGH EXTENDING ALONG 31N30W 25N32W 19N40W. SCATTERED
SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS AND N OF
25N. THE REMAINDER OF THE AREA IS UNDER THE INFLUENCE OF A SFC
RIDGE. IN THE UPPER LEVELS...A TROUGH/RIDGE/TROUGH/RIDGE PATTERN
DOMINATES THE DISCUSSION AREA. A DEEP LAYERED TROUGH IS OVER THE
EASTER U.S. AND THE W ATLC. A RIDGE IS OVER THE W-CENTRAL
ATLANTIC BETWEEN 50W-65W. AN UPPER-LEVEL TROUGH EXTENDS FROM AN
UPPER-LEVEL LOW LOCATED 32N40W TO 15N50W. A JET-STREAM BRANCH
WITH CORE WINDS OF 110-130 KT IS ON THE WESTERN SIDE OF THE LOW.
ANOTHER MAXIMUM WINDS OF 90 KT IS SE OF THE UPPER LOW PASSING
NEAR 21N30W. A RIDGE DOMINATES THE E ATLC AND WEST AFRICA.

$$
GR




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