[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230555
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI OCT 23 2009

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS TILTED FROM 12N38W TO 19N34W MOVING NW NEAR 10
KT. THE WAVE IS EMBEDDED WITHIN A MAXIMUM IN DEEP LAYER MOISTURE
AS DEPICTED BY TOTAL PRECIPITABLE WATER IMAGERY N OF 10N BETWEEN
27W-40W. CIMSS WAVETRAK MODEL GUIDANCE ALSO INDICATES AN AREA OF
850 MB RELATIVE VORTICITY IN THE VICINITY OF THE WAVE AXIS N OF
10N. SCATTERED MODERATE CONVECTION IS OCCURRING FROM 12N-22N
BETWEEN 26W-37W PRIMARILY EAST OF THE WAVE AXIS. THIS ACTIVITY
IS BEING ENHANCED BY AN AREA OF UPPER LEVEL DIFFLUENCE LOCATED E
OF AN UPPER LEVEL SHORTWAVE TROUGH WITH AXIS DIPPING SOUTH TO
18N ALONG 35W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 8N33W 6N57W. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE FROM 3N-11N BETWEEN 20W-38W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 0300 UTC...A COLD FRONT ENTERS THE GULF NEAR ATCHAFALAYA
BAY AND EXTENDS SW ALONG 25N94W INTO EASTERN MEXICO NEAR 23N98W
TURNING STATIONARY ALONG THE EASTERN SLOPES OF THE SIERRA MADRE
ORIENTAL MOUNTAINS. A PRE-FRONTAL SURFACE TROUGH EXTENDS FROM
26N92W TO 22N94W. LOW-LEVEL CONVERGENCE NEAR BOTH OF THESE
SURFACE BOUNDARIES IS GENERATING NUMEROUS SHOWERS AND SCATTERED
TSTMS WITHIN 120 NM OF A LINE FROM 23N93W TO INLAND OVER
SOUTHERN ALABAMA NEAR MOBILE BAY. THE FRONT IS SUPPORTED BY A
BROAD UPPER TROUGH ACROSS THE CENTRAL CONUS WITH THE UPPER LOW
CENTERED OVER WESTERN IOWA. A DRY AND STABLE AIRMASS FOLLOWS
BEHIND THE FRONT WITH NW WINDS UP TO 20 KT. AN UPPER LEVEL RIDGE
ANCHORED OVER THE BAY OF CAMPECHE NEAR 19N93W EXTENDS A RIDGE
AXIS NE OVER THE NE GULF AND FLORIDA PANHANDLE THUS ENHANCING
THE CONVECTION ASSOCIATED WITH THE COLD FRONT.

CARIBBEAN SEA...
A 1007 MB LOW REMAINS IN THE SW CARIBBEAN OFF THE COAST OF
NICARAGUA NEAR 13N82W. MOSTLY SCATTERED SHOWERS ACCOMPANY THIS
LOW ACROSS THE SW CARIBBEAN S OF 15N W OF 78W AS MOST CONVECTION
IS BEING INHIBITED BY HIGH SHEAR VALUES NEAR THE BASE OF A
HIGHLY AMPLIFIED UPPER LEVEL TROUGH THAT EXTENDS FROM THE SW
NORTH ATLC ACROSS EASTERN CUBA TO NICARAGUA AND HONDURAS. THIS
TROUGH IS LOCATED BETWEEN A BROAD UPPER LEVEL RIDGE OVER THE
GULF OF MEXICO AND A SECOND UPPER LEVEL RIDGE ANCHORED OVER
VENEZUELA THAT EXTENDS A RIDGE AXIS ACROSS THE EASTERN CARIBBEAN
ALONG 67W. THIS UPPER LEVEL PATTERN IS PROVIDING THE NW AND FAR
EASTERN CARIBBEAN WITH STRONG SUBSIDENCE AND A DRY AIRMASS IN
PLACE WITH ONLY A FEW ISOLATED SHOWERS OBSERVED ON SATELLITE
IMAGERY MOVING ACROSS THE LEEWARD ISLANDS AND PUERTO RICO. A
SWATH OF MOISTURE IS ACROSS THE CENTRAL CARIBBEAN WITH SCATTERED
SHOWERS FROM 10N-20N BETWEEN 71W-78W. AN AREA OF SCATTERED TSTMS
IS OCCURRING NORTH OF THE GUAJIRA PENINSULA FROM 11N-13N BETWEEN
72W-75W. THE ITCZ AXIS EXTENDS FROM NW COLOMBIA ACROSS THE SW
CARIBBEAN ALONG 10N AND INTO THE E PACIFIC REGION  GENERATING
SCATTERED SHOWERS S OF 11N W OF 79W.

ATLANTIC OCEAN...
A NARROW AMPLIFIED UPPER LEVEL TROUGH AXIS EXTENDS SW FROM
30N70W THROUGH THE CENTRAL BAHAMAS AND EASTERN CUBA DIPPING S
INTO THE WESTERN CARIBBEAN SEA. THIS UPPER LEVEL TROUGH IS
PROVIDING STRONG SUBSIDENCE AND DRY STABLE AIR W OF 76W AND ALSO
SUPPORTS A SURFACE TROUGH ANALYZED FROM 27N71W TO THE WINDWARD
PASSAGE NEAR 20N74W. LOW-LEVEL CONVERGENCE NEAR THE SURFACE
TROUGH COUPLED WITH UPPER LEVEL DIFFLUENCE E OF THE UPPER LEVEL
TROUGH AXIS IS GENERATING SCATTERED SHOWERS FROM 20N-27N BETWEEN
66W-76W. A BROAD UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLC N
OF 28N AND SUPPORTS A COLD FRONT N OF THE REGION TO NEAR 31N42W.
LINGERING WEAK LOW-LEVEL CONVERGENCE TRAILS TO THE WEST ALONG
26N BETWEEN 52W-65W AND CONTINUES TO PRODUCE ISOLATED LOW-LEVEL
SHOWERS FROM 23N-27N BETWEEN 53W-65W. EAST OF THE COLD FRONT
ACROSS THE CENTRAL ATLC...A PRE-FRONTAL SURFACE TROUGH IS
ANALYZED FROM 24N46W TO BEYOND 32N36W WITH SCATTERED SHOWERS AND
ISOLATED TSTMS OCCURRING WITHIN 200 NM E OF THE SURFACE TROUGH.
EAST OF THE SURFACE TROUGH ACROSS THE EASTERN ATLC...A SURFACE
RIDGE IS PRESENT ANCHORED BY A 1022 MB HIGH CENTERED OVER THE
MADEIRA ISLANDS. IN THE TROPICAL ATLC...A 1011 MB LOW IS N OF
THE ITCZ AXIS WITH ISOLATED SHOWERS WITHIN 200 NM RADIUS OF THE
LOW CENTER.

$$
HUFFMAN



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