[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291758
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED OCT 29 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...
TROPICAL WAVE IS ALONG 52W S OF 16N MOVING W 10-15 KT. CIMSS
WAVETRAK PRODUCT SHOWS THAT LOW LEVEL CYCLONIC CIRCULATION IS
MAXIMIZED ALONG WAVE AXIS. WAVE IS AT THE LEADING EDGE OF A
WESTWARD-MOVING SURGE IN DEEP LAYER MOISTURE BASED ON TOTAL
PRECIPITABLE WATER PRODUCT FROM CIMSS. ISOLATED MODERATE
CONVECTION IS FROM 10N-16N BETWEEN 48W-53W.

TROPICAL WAVE IS ALONG 64W/65W FROM 10N-19N MOVING W 10-15 KT.
VISIBLE SATELLITE IMAGERY DEPICTS A WELL-DEFINED INVERTED-V
SIGNATURE IN CLOUD PATTERN COINCIDING WITH THE WAVE AXIS...
WHICH ALSO COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE.
ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF WAVE AXIS N OF
12N.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 12N15W 9N28W 9N37W 9N49W 8N61W. A
SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ...AND THIS TROUGH
EXTENDS FROM 14N40W...TO A 1012 MB SURFACE LOW NEAR 11N40W...TO
8N40W. LOW LEVEL CONVERGENCE NEAR THESE FEATURES IS RESULTING IN
SCATTERED MODERATE CONVECTION FROM 10N-13N BETWEEN 37W-39W.
ADDITIONALLY...ISOLATED MODERATE CONVECTION IS WITHIN 210 NM
EITHER SIDE OF ITCZ AXIS BETWEEN 17W-32W. ISOLATED MODERATE
CONVECTION IS WITHIN 90 NM N OF ITCZ AXIS BETWEEN 45W-49W.
SIMILAR CONVECTION IS WITHIN 60 NM EITHER SIDE OF ITCZ AXIS
BETWEEN 57W-60W.

...DISCUSSION...

GULF OF MEXICO...
GENERALLY FAIR WEATHER AND DRY CONDITIONS PREVAIL ACROSS THE
GULF REGION...AS A MODIFIED CONTINENTAL POLAR AIRMASS
PERSISTS...WITH TEMPERATURES BELOW SEASONAL AVERAGES ACROSS THE
N GULF COAST. THIS RELATIVELY COOL AND DRY AIRMASS IS BEING
SUPPORTED BY A 1031 MB SURFACE HIGH IN THE SE CONUS. WEAK
LOW-LEVEL INSTABILITY RESULTING FROM THE COOLER AIR PERSISTING
OVER THE RELATIVELY WARMER GULF WATERS IS MAINTAINING THE
PRESENCE OF STRATOCUMULUS CLOUDS OVER MUCH OF THE GULF. ALSO...
STRONG SOUTHWESTERLY FLOW ALOFT IS BRINGING UPPER LEVEL MOISTURE
AND HIGH CLOUDS FROM THE E PACIFIC REGION INTO THE W GULF.
ADDITIONALLY...STRONG NE SURFACE WINDS ARE BLOWING THROUGH THE
ISTHMUS OF TEHUANTEPEC RESULTING IN GALE FORCE WINDS IN THE E
PACIFIC REGION.

CARIBBEAN SEA...
A COLD FRONT EXTENDS FROM W HAITI NEAR 20N72W TO 16N78W TO E
HONDURAS NEAR 15N85W. THIS FRONT IS INTERACTING WITH MOISTURE IN
DIFFLUENT SW FLOW ALOFT TO RESULT IN ENHANCED CLOUD BANDS AND
ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE COLD FRONT.
DEEP MOISTURE PRESENT OVER THE SW CARIBBEAN COMBINED WITH UPPER
LEVEL DIFFLUENCE IS RESULTING IN SCATTERED MODERATE CONVECTION
FROM 8N-12N BETWEEN 77W-82W...AFFECTING PORTIONS OF PANAMA AND
COSTA RICA. FARTHER TO THE E...AN UPPER RIDGE AXIS EXTENDS FROM
AN UPPER HIGH IN THE SW ATLC NEAR 23N62W TO THE NE CARIBBEAN
NEAR 17N69W. DEEP LAYER DRY AIR EMBEDDED WITHIN THIS RIDGE IS
RESULTING IN MAINLY FAIR WEATHER ACROSS THE E CARIBBEAN.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH IS OVER THE W ATLC...WITH MUCH OF THE ENERGY
ASSOCIATED WITH THE TROUGH NOW N OF THE DISCUSSION AREA. THIS
TROUGH CONTINUES TO SUPPORT A COLD FRONT THAT EXTENDS FROM
32N61W TO 25N66W TO W HAITI NEAR 20N72W. DEEP LAYER DRY AIR
EMBEDDED WITHIN THE TROUGH IS RESULTING IN GENERALLY FAIR
WEATHER IN THE WAKE OF THE FRONT...WHERE A RELATIVE DRY AND COOL
MODIFIED CONTINENTAL POLAR AIRMASS IS IN PLACE. HOWEVER...
ATMOSPHERIC LIFT IN MOIST SOUTHWESTERLY FLOW ALOFT IS SUPPORTING
ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE COLD FRONT.
FARTHER TO THE E...AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE SW
ATLC NEAR 19N66W TO AN UPPER HIGH ALSO OVER THE SW ATLC NEAR
23N62W TO 32N54W. A WEAK SURFACE TROUGH E OF THE UPPER RIDGE
AXIS EXTENDS FROM 31N52W TO 27N54W TO 24N57W...WITH ISOLATED
SHOWERS WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH S OF 29N.
FARTHER TO THE E...A DEEP LAYER TROUGH IS N OF 23N E OF 30W. DRY
AIR EMBEDDED WITHIN THE TROUGH IS INHIBITING DEEP CONVECTIVE
DEVELOPMENT NEAR THIS FEATURE. ADDITIONALLY...THIS TROUGH IS
SUPPORTING A COLD FRONT MIDWAY BETWEEN THE CANARY ISLANDS AND
THE CAPE VERDE ISLANDS. THIS FRONT EXTENDS FROM THE W COAST OF
AFRICA NEAR 24N16W TO 24N27W TO 30N36W...AND A BAND OF INCREASED
CLOUDINESS IS WITHIN 30 NM EITHER SIDE OF THE COLD FRONT. OVER
THE TROPICAL ATLC...AN EAST-TO-WEST UPPER RIDGE IS ALONG 12N
BETWEEN THE AFRICAN COAST AND 44W...AND A SURFACE TROUGH IS
EMBEDDED WITHIN THE ITCZ. THIS TROUGH EXTENDS FROM 14N40W...TO A
1012 MB SURFACE LOW NEAR 11N40W...TO 8N40W. LOW LEVEL
CONVERGENCE NEAR THESE FEATURES IS RESULTING IN SCATTERED
MODERATE CONVECTION FROM 10N-13N BETWEEN 37W-39W...WHICH IS
BEING ENHANCED BY UPPER LEVEL DIVERGENCE NEAR THE UPPER RIDGE
AXIS.

$$
COHEN



This weather bulletin was brought to you by:
www.nashvilleweather.net