[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 241749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON SEP 24 2012

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC. GOES-E IS CURRENTLY EXPERIENCING AN OUTAGE.
GOES-W IS IN FULL DISK MODE TO PROVIDE IMAGERY OVER THE CONUS
AND GULF OF MEXICO.

...SPECIAL FEATURES...

TROPICAL STORM NADINE WAS LOCATED NEAR 31.7N 27.8W AT 24/1500
UTC. THIS POSITION IS LOCATED ABOUT 380 NM S OF THE AZORES
ISLANDS. NADINE IS MOVING WNW NEAR 6 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 993 MB. MAXIMUM SUSTAINED WIND SPEED IS 45
KT WITH GUST TO 55 KT. PLEASE SEE LATEST NHC FORECAST/ ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
SCATTERED MODERATE CONVECTION IS FROM 33N-34N BETWEEN
26N-28N...AND FROM 31N-32N BETWEEN 28W-30W.

...TROPICAL WAVES...

TROPICAL WAVE IS E OF THE LESSER ANTILLES EXTENDING FROM 17N57W
TO 11N59W MOVING W AT 15 KT. THE WAVE HAS LOST A LOT OF ITS
ENERGY AS SOME OF THE ENERGY WAS SPREAD OUT HORIZONTALLY AHEAD
OF IT...WHICH IS EVIDENT IN THE HIGH MOISTURE VALUES ACROSS THE
SE CARIBBEAN. THERE IS ALSO A SMALL PATCH OF ENHANCED MOISTURE
EAST OF THE WAVE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. NO
DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF
MAURITANIA AT 19N16W AND CONTINUES ACROSS THE ATLC ALONG 13N22W
9N28W 8N32W. THE ITCZ BEGINS AT 8N32W ALONG 10N40W 11N46W.
SCATTERED MODERATE CONVECTION IS FROM 11N-13N BETWEEN 18W-20W.
SIMILAR ACTIVITY IS FROM 7N-10N BETWEEN 21W-36W.

...DISCUSSION...

GULF OF MEXICO...
SATELLITE IMAGERY IS LIMITED ACROSS THE GULF OF MEXICO DUE TO
THE GOES-E OUTAGE. MORE RELIANCE HAS BEEN PLACED ON BOTH SURFACE
OBSERVATIONS AND MODEL DATA. THE COLD FRONT THAT HAS BEEN MOVING
THROUGH THE BASIN HAS BECOME STATIONARY AS OF 1500 UTC. IT
EXTENDS FROM NEAR LAKE OKEECHOBEE FLORIDA AT 27N81W TO 24N86W
AND ENDING NEAR 25N92W. THE FRONT IS SUPPORTED BY A BROAD UPPER
LEVEL TROUGH MOVING OFF THE EASTERN UNITED STATES SEABOARD. A
SHORTWAVE UPPER TROUGH AXIS IS ALSO EXTENDING DOWN THE WESTERN
GULF ALONG 94W. FROM THE AVAILABLE WATER VAPOR IMAGERY...DRY AIR
ALOFT COVERS THE MAJORITY OF THE NORTHERN GULF WHERE CLEAR SKIES
AND FAIR WEATHER ARE NOTED. MOIST CONDITIONS COVER THE REMAINDER
OF THE BASIN NEAR THE FRONT AND NEAR A SURFACE TROUGH IN THE SW
GULF ALONG 22N95W TO 18N93W. IT APPEARS THAT SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 25N ACROSS THE BASIN
WITH RADAR IMAGERY INDICATING SIMILAR ACTIVITY THROUGH THE
FLORIDA STRAITS. MODEL GUIDANCE INDICATES THAT THE FRONT WILL
REMAIN STATIONARY AND EVENTUALLY DISSIPATE WITH THE MOISTURE
ASSOCIATED WITH IT RETREATING NORTHWARD IN THE MIDDLE OF THE
WEEK.

CARIBBEAN SEA...
THE CARIBBEAN IS HIT HARDEST WITH THE SATELLITE OUTAGE WITH ONLY
A PORTION OF THE NW CARIBBEAN BEGIN COVERED BY THE GOES-W FULL
DISK IMAGERY. SOME VERY LOW RESOLUTION DATA IS AVAILABLE ON THE
WESTERN EDGE OF METEOSAT-9 IMAGERY...WHICH COVERS THE FAR
EASTERN CARIBBEAN. THIS LEAVES THE CENTRAL CARIBBEAN MOSTLY IN
THE DARK BESIDES SURFACE OBSERVATIONS AND MODEL GUIDANCE.
LUCKILY...IT APPEARS THAT MOSTLY FAIR WEATHER PREVAILS ACROSS
THE MAJORITY OF THE BASIN. THE NW CARIBBEAN AND MUCH OF CENTRAL
AMERICA ARE UNDER MOSTLY CLEAR SKIES. THE MONSOON TROUGH EXTENDS
FROM COSTA RICA TO NORTHERN COLOMBIA. EVEN WITHOUT SATELLITE
IMAGERY...LIGHTNING DATA HELPS TO INDICATE THAT SCATTERED
SHOWERS/THUNDERSTORMS ARE ACROSS PORTIONS OF COSTA
RICA...PANAMA...AND NORTHERN COLOMBIA. TOTAL PRECIPITABLE WATER
IMAGERY ALSO INDICATES HIGHER MOISTURE VALUES ARE ACROSS THIS
AREA...AS WELL AS ACROSS THE SE CARIBBEAN. THE LOW RESOLUTION
DATA AVAILABLE FROM METEOSAT-9 INDICATES THAT SCATTERED
SHOWERS/THUNDERSTORMS ARE ACROSS THE SE CARIBBEAN S OF 15N
BETWEEN 62W-66W. ASCAT SCATTEROMETER DATA INDICATES THAT
TRADEWIND FLOW IS PRESENT ACROSS MUCH OF THE BASIN WITH SPEEDS
OF 15-20 KTS. ALOFT...AN UPPER LEVEL RIDGE EXTENDS FROM
GUATEMALA ACROSS CENTRAL CUBA INTO THE WEST ATLC. AN UPPER LEVEL
TROUGH EXTENDS FROM PUERTO RICO TO COLOMBIA COVERING THE CENTRAL
AND EASTERN CARIBBEAN. THIS IS BASED MAINLY ON MODEL GUIDANCE.
MUCH OF THE SOUTHERN HALF OF THE CARIBBEAN WILL REMAIN MOIST FOR
THE NEXT 24 HOURS. A TROPICAL WAVE EAST OF THE LESSER ANTILLES
WILL APPROACH THE EASTERN CARIBBEAN WITHIN THE NEXT 24 HOURS.

ATLANTIC OCEAN...
THE WESTERN ATLC IS UNDER LIMITED SATELLITE IMAGERY TODAY.
LUCKILY THE GOES-W FULL DISK IMAGERY DOES CAPTURE THE COLD FRONT
DRAPED ACROSS THE BASIN. IT ENTERS THE DISCUSSION AREA NEAR
32N71W CONTINUING ALONG 28N76W TO THE COAST OF FLORIDA AT
27N80W. A SURFACE TROUGH IS AHEAD OF THE FRONT ALONG 27N76W. THE
FRONT IS NEAR THE EDGE OF THE IMAGERY SO THE RESOLUTION IS NOT
VERY GOOD...BUT IT APPEARS THAT SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS EXTEND 200 NM SE OF THE AXIS. THE FRONT IS
SUPPORTED BY AN UPPER LEVEL TROUGH MOVING OFF THE EASTERN
SEABOARD. AN UPPER LEVEL RIDGE IS TO THE E EXTENDING FROM
CENTRAL CUBA TO NEAR 33N62W SUPPORTING SURFACE RIDGING ACROSS
THE REMAINDER OF THE W ATLC EXTENDING FROM A HIGH CENTER IN THE
N CENTRAL ATLC. NO SATELLITE IMAGERY IS AVAILABLE ACROSS THIS
AREA...BUT THERE IS LIKELY LITTLE ACTIVE WEATHER. METEOSAT-9
CAPTURES THE CENTRAL ATLC ON THE EDGE OF ITS IMAGERY PROVIDING
SOME INSIGHT OVER THIS AREA. AN UPPER LEVEL LOW IS SPINNING NEAR
27N58W AND IS SUPPORTING A FEW POSSIBLE SHOWERS N OF 25N BETWEEN
56W-58W. FARTHER E...A WEAK SURFACE TROUGH EXTENDS FROM 22N44W
TO 20N47W WITH POSSIBLE ISOLATED SHOWERS WITHIN 100 NM EITHER
SIDE OF ITS AXIS. THE REMAINDER OF THE E ATLC IS COVERED BY WEAK
SURFACE RIDGING AROUND A 1016 MB HIGH NEAR 21N28W. TROPICAL
STORM NADINE IS N OF THE HIGH CENTER. SEE SPECIAL FEATURES
ABOVE. ALOFT...AN UPPER LEVEL TROUGH EXTENDS FROM NEAR 28N34W TO
12N46W. UPPER LEVEL RIDGING COVERS THE REMAINDER OF THE EAST
ATLC CENTERED OVER NW AFRICA NEAR 22N12W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

WALTON




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