[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231027
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE OCT 23 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 61W/62W S OF 21N MOVING W 10-15 KT. THE N
END OF THE WAVE IS JUST TO THE E OF A DEVELOPING UPPER LOW WHILE
THE REMAINDER OF THE WAVE REMAINS BENEATH THE WESTERN EDGE OF A
BROAD UPPER RIDGE PARTIALLY MASKING THE SATELLITE SIGNATURE AND
DISPLACING THE DEEPEST CONVECTION TO THE E. SCATTERED MODERATE/
STRONG CONVECTION IS FROM 12N-18N BETWEEN 52W-59W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N12W 7N21W 9N45W 8N53W 10N61W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG TO SCATTERED
STRONG CONVECTION ARE FROM 3N-10N BETWEEN 12W-40W.

DISCUSSION...

GULF OF MEXICO...
STRONG COLD FRONT CONTINUES TO MOVE ACROSS THE GULF EXTENDING
FROM A 1005 MB LOW OVER N MISSISSIPPI ACROSS EXTREME SE
LOUISIANA INTO THE GULF NEAR 30N89W ALONG 24N92W INTO MEXICO
JUST S OF VERACRUZ TO THE E SLOPES OF THE SIERRA MADRE
MOUNTAINS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN
60 NM E OF THE FRONT N OF 26N AND WITHIN 90/120 NM W OF THE
FRONT S OF 26N. DEEP LAYERED EASTERLY FLOW ACROSS THE YUCATAN
AND E BAY OF CAMPECHE ARE GENERATING HEAVY SHOWERS AND STRONG
THUNDERSTORMS W OF A LINE TO THE FRONT FROM 26N90W TO OVER S
MEXICO NEAR 18N92W. THE EXCEPTION IS ALONG THE COAST OF TEXAS
WHERE RAPID CLEARING IS OCCURRING DUE TO THE DRY STABLE AIR
ASSOCIATED WITH THE DEEP LAYERED TROUGH THAT IS CURRENTLY OVER
THE CENTRAL PLAIN STATES TO ACROSS THE MISSISSIPPI VALLEY AND
INCLUDING THE W GULF. STORM FORCE NORTHERLY SURFACE WINDS ARE W
OF THE FRONT. AN UPPER HIGH IN THE W ATLC EXTENDS A RIDGE ACROSS
FLORIDA COVERING THE E GULF. LOW LEVEL SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS ARE MOVING ACROSS S FLORIDA AND
THROUGH THE FLORIDA STRAITS IN THE RETURN FLOW AROUND A SURFACE
HIGH IN THE W ATLC S OF 26N E OF 85W.

CARIBBEAN SEA...
AN UPPER LEVEL SHEAR AXIS BISECTS THE CARIBBEAN EXTENDING ACROSS
THE VIRGIN ISLANDS ALONG 16N70W OVER JAMAICA THEN SW TO AN UPPER
LOW OVER THE W COAST OF NICARAGUA IN THE E PACIFIC REGION. DRY
SOMEWHAT STABLE AIR IS N OF THE SHEAR AXIS WHILE VERY MOIST
TROPICAL AIR WITH S AND W UPPER FLOW IS TO THE S. AN AREA OF
CONVERGENCE BETWEEN THE SW UPPER FLOW AND LOW LEVEL EASTERLY
SURFACE FLOW IS GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 12N-18N BETWEEN 78W-85W INCLUDING THE COAST
OF N NICARAGUA/E HONDURAS. THE ITCZ AXIS CROSSES THE N PORTION
OF SOUTH AMERICA AND PANAMA INTO THE E PACIFIC REGION GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 13N BETWEEN THE
WINDWARD ISLANDS AND 80W. LIGHT/MODERATE EASTERLY TRADE WINDS
ACROSS THE CARIBBEAN ARE USHERING IN LOW LEVEL POPCORN TYPE
SHOWERS ESPECIALLY E OF 80W.

ATLANTIC OCEAN...
THE UPPER HIGH IS JUST OFF THE NE FLORIDA COAST NEAR 31N80W
GIVING THE W ATLC S TO SW UPPER FLOW W OF 65W. A SURFACE RIDGE
COVERS THE W AND MOST OF THE CENTRAL ATLC N OF 23N W OF 45W
ANCHORED BY A 1026 MB HIGH N OF BERMUDA NEAR 37N65W. AN UPPER
SHEAR AXIS EXTENDS INTO THE CARIBBEAN ACROSS THE VIRGIN ISLANDS
FROM A DEVELOPING UPPER LOW ROUGHLY LOCATED NEAR 20N63W. A
NARROW SWATH OF DRY STABLE AIR IS S OF 23N OVER THE GREATER
ANTILLES W OF 63W. AN UPPER RIDGE OVER THE W TROPICAL ATLC
EXTENDS ALONG 54W TO 23N ENHANCING ACTIVITY ASSOCIATED WITH THE
TROPICAL WAVE AND PROVIDING ENOUGH DIFFLUENCE TO GENERATE
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 125 NM OF A LINE
FROM 21N54W TO 26N66W. A LARGE CUT-OFF UPPER LOW IS IN THE
E/CENTRAL ATLC NEAR 27N35W WITH A 1009 MB SURFACE LOW CENTERED
NEAR 29N37W AND A SURFACE TROUGH EXTENDING S TO 20N40W. CLUSTERS
OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVERS A BROAD AREA
FROM 18N TO BEYOND 32N BETWEEN 29W-38W. WEAK UPPER HIGH IS ALONG
THE COAST OF WESTERN SAHARA/MAURITANIA BORDER COVERING THE
REMAINDER OF THE E ATLC. WEAK SURFACE RIDGE COVERS THE REMAINDER
OF THE E ATLC WITH DRY STABLE AIR.

$$
WALLACE



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