[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 240624 AAA
TWDAT

TROPICAL WEATHER DISCUSSION...UPDATED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON NOV 24 2008

...UPDATED TO INCLUDE INFORMATION REGARDING A FORECAST GALE IN
THE ATLC...

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
0445 UTC.

...SPECIAL FEATURE...
IN THE SW CARIBBEAN...A 1007 MB SURFACE LOW IS CENTERED N OF
PANAMA NEAR 10N80W. LOW LEVEL CONVERGENCE IN THE VICINITY OF
THIS SURFACE LOW IS INTERACTING WITH DEEP LAYER MOISTURE OVER
THE W CARIBBEAN TO RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS
OVER THE CARIBBEAN S OF 15N W OF 77W...INCLUDING PORTIONS OF
COSTA RICA...PANAMA...AND E NICARAGUA. THIS SHOWER AND
THUNDERSTORM ACTIVITY HAS INCREASED AND BECOME BETTER ORGANIZED
OVER THE LAST DAY...AND SOME ADDITIONAL DEVELOPMENT OF THIS
SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS IT DRIFTS
SLOWLY WESTWARD. REGARDLESS OF WHETHER OR NOT A TROPICAL CYCLONE
FORMS...HEAVY RAINFALL AND LOCALIZED FLOODING WILL BE POSSIBLE
OVER PORTIONS OF PANAMA...COSTA RICA...AND NICARAGUA DURING THE
NEXT COUPLE OF DAYS.

...TROPICAL WAVES...
TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN ALONG 74W S OF 17N
MOVING W 10-15 KT. SATELLITE IMAGERY INDICATES CYCLONIC
CIRCULATION COINCIDING WITH THIS WAVE. A MAXIMUM IN DEEP LAYER
MOISTURE COINCIDES WITH THIS WAVE BASED ON TOTAL PRECIPITABLE
WATER PRODUCT FROM CIMSS. ALSO...UPPER AIR TIME-HEIGHT ANALYSIS
FOR CURACAO...LOCATED IN THE NETHERLANDS ANTILLES NEAR
12N69W...RECENTLY DEPICTS VEERING OF THE MEAN LOW/MID-LEVEL FLOW
FROM NE TO SE...SUGGESTING THAT THIS WAVE HAS LIKELY MOVED W OF
CURACAO. SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN
150 NM EITHER SIDE OF THE WAVE AXIS S OF 16N. THIS WAVE IS
BECOMING ABSORBED BY THE BROAD LOW LEVEL CYCLONIC CIRCULATION
ASSOCIATED WITH THE 1007 MB SURFACE LOW NEAR 10N80W...WHICH IS
DISCUSSED IN THE SPECIAL FEATURE SECTION ABOVE.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 9N12W 4N22W 6N33W 9N45W 6N58W.
SCATTERED MODERATE IS FROM 5N-7N BETWEEN 18W-23W. SCATTERED
MODERATE CONVECTION IS ALSO FROM 5N-8N BETWEEN 28W-31W. SIMILAR
CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN
40W-49W.

...DISCUSSION...

GULF OF MEXICO...
STRONG SOUTHWESTERLY AND WESTERLY UPPER LEVEL WINDS COVER THE
GULF REGION. AS A RESULT...UPPER LEVEL MOISTURE...ORIGINATING
FROM THE E PACIFIC REGION...IS STREAMING ACROSS THE N GULF. AT
THE SURFACE...A RELATIVELY COOL AND DRY AIRMASS IS IN PLACE
ACROSS THE GULF REGION...WITH TEMPERATURES GENERALLY BELOW
SEASONAL AVERAGES. THIS AIRMASS IS BEING SUPPORTED BY A 1032 MB
SURFACE HIGH OVER SOUTH CAROLINA NEAR 34N80W...WITH AN
ASSOCIATED SURFACE RIDGE EXTENDING ACROSS THE NE GULF.
SUBSIDENCE AND STABLE ATMOSPHERIC CONDITIONS ARE INHIBITING DEEP
CONVECTION ACROSS THE GULF REGION. FARTHER NORTH...A VIGOROUS
UPPER TROUGH IS OVER THE PLAINS OF THE CONUS...WITH AN
ASSOCIATED SURFACE FRONT EXTENDING FROM THE SOUTHERN PLAINS OF
THE CONUS TO THE ROCKY MOUNTAINS. AS THIS UPPER TROUGH
TRANSLATES SOUTHEASTWARD OVER THE NEXT DAY...THE FRONT WILL
APPROACH THE N GULF REGION. IN THE WAKE OF THIS FRONT...A
REINFORCING COOLER AND DRIER AIRMASS...CHARACTERIZED AS A
MODIFIED CONTINENTAL POLAR AIRMASS...IS PRESENT. ADDITIONALLY...
STRONG N TO NE SURFACE WINDS ARE BLOWING THROUGH THE ISTHMUS OF
TEHUANTEPEC RESULTING IN GALE FORCE WINDS IN THE E PACIFIC
REGION. THESE WINDS ARE FORECAST TO HAVE DIMINISHED BELOW GALE
FORCE AT 25/0600 UTC.

CARIBBEAN SEA...
IN THE SW CARIBBEAN...A 1007 MB SURFACE LOW NEAR 10N80W IS
SUPPORTING SHOWER AND THUNDERSTORM ACTIVITY...WHICH IS DISCUSSED
IN THE SPECIAL FEATURE SECTION ABOVE. THE INCREASED SURFACE
PRESSURE GRADIENT ASSOCIATED WITH THIS SURFACE LOW IS SUPPORTING
NE SURFACE WINDS OF 20 TO 30 KT FOR LOCATIONS FROM 12N-15N W OF
75W AND FOR LOCATIONS N OF 15N BETWEEN 69W-75W IN THE E
CARIBBEAN INCLUDING THE WINDWARD PASSAGE...WHICH ARE EXPECTED TO
CONTINUE THROUGH MONDAY NIGHT. THE SHOWER AND THUNDERSTORM
ACTIVITY ASSOCIATED WITH THE SURFACE LOW IS BEING ENHANCED BY
UPPER LEVEL DIFFLUENCE IN THE VICINITY OF AN UPPER RIDGE PRESENT
OVER THE W CARIBBEAN...WITH THE AXIS OF THIS UPPER RIDGE
EXTENDING FROM N COLOMBIA NEAR 11N72W TO 15N78W TO THE NW
CARIBBEAN NEAR 16N80W. A WEAKENING SURFACE STATIONARY FRONT IN
THE NW CARIBBEAN EXTENDS FROM 20N80W TO E CUBA NEAR
21N76W...WITH SCATTERED SHOWERS WITHIN 60 NM OF THIS FRONT. OVER
THE E AND CENTRAL CARIBBEAN...UPPER LEVEL DIFFLUENCE IS
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS S OF 16N BETWEEN
66W-71W. THIS ACTIVITY IS BEING ENHANCED BY LOW LEVEL
CONVERGENCE ASSOCIATED WITH THE TROPICAL WAVE ALONG 74W
DISCUSSED IN THE TROPICAL WAVES SECTION ABOVE.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH OVER THE W ATLC IS SUPPORTING A SURFACE
STATIONARY FRONT THAT EXTENDS FROM E CUBA NEAR 21N76W TO 25N60W
TO 32N53W TO NE OF THE DISCUSSION AREA. ISOLATED SHOWERS ARE
OCCURRING WITHIN 60 NM EITHER SIDE OF THIS FRONT. THIS FRONT IS
WEAKENING W OF 71W. TO THE W OF THIS STATIONARY FRONT...A
RELATIVELY COOLER AND DRIER AIRMASS IS IN PLACE...WITH
TEMPERATURES BELOW SEASONAL AVERAGES ACROSS FLORIDA. THIS
AIRMASS IS BEING SUPPORTED BY A 1032 MB SURFACE HIGH OVER SOUTH
CAROLINA NEAR 34N80W. ALSO...A 1003 MB SURFACE LOW IS FORECAST
TO FORM NEAR 32N53W OVER THE NEXT DAY...WITH GALE FORCE SURFACE
WINDS WITHIN 240 NM OF THE SW QUADRANT OF THE SURFACE LOW.
FARTHER TO THE E...A SURFACE TROUGH EXTENDS FROM 14N59W TO A
1011 MB SURFACE LOW NEAR 14N55W TO 13N50W. ISOLATED SHOWERS ARE
OCCURRING WITHIN 60 NM OF THIS SURFACE LOW AND SURFACE TROUGH.
TO THE E...AN UPPER TROUGH IS PRESENT OVER THE E ATLC N OF 20N E
OF 44W WITH AN UPPER LOW NEAR 30N33W. AN ASSOCIATED SURFACE
TROUGH EXTENDS FROM 28N35W TO A 1014 MB SURFACE LOW NEAR 22N35W
TO 17N41W. LOW LEVEL CONVERGENCE NEAR THE SURFACE TROUGH AND
SURFACE LOW IS SUPPORTING SCATTERED SHOWERS FROM 22N-29N BETWEEN
24W-35W. ALSO...UPPER LEVEL DIVERGENCE IN THE VICINITY OF A
MID/UPPER-LEVEL WIND SPEED MAXIMUM OVER THE E ATLC IS SUPPORTING
SCATTERED SHOWERS FROM 14N-19N BETWEEN 16W-27W.

$$
COHEN




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