[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171751
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN OCT 17 2010

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.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N22W 7N29W 10N36W 7N45W 8N51W.
A SURFACE TROUGH IS ANALYZED JUST OFFSHORE OF W AFRICA ALONG
17N19W TO 9N20W. AN ASCAT SCATTEROMETER PASS INDICATES SHARP
LOW-LEVEL CYCLONIC FLOW ABOUT THE AXIS. NUMEROUS STRONG
CONVECTION IS E OF THE AXIS FROM 13N-17N BETWEEN 14W-17W.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-19N BETWEEN
14W-21W. A SECOND EMBEDDED SURFACE TROUGH IS FROM 10N27W TO
14N26W WITH SCATTERED MODERATE CONVECTION FROM 10N-14N BETWEEN
23W-28W. SIMILAR ACTIVITY IS ALSO FROM 3N-8N BETWEEN 23W-30W. A
SURFACE TROUGH IS ALSO IN THE CENTRAL TROPICAL ATLC ALONG 16N35W
TO 7N39W WITH A SURFACE LOW ALONG THE TROUGH NEAR 11N38W.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 4N-10N BETWEEN
31W-42W. ALL THREE OF THESE SURFACE TROUGHS ARE EMBEDDED IN A
LARGE SCALE CYCLONIC GYRE WHICH IS CONTRIBUTING TO THE SMALLER
PERTURBATIONS OF EACH TROUGH. THE PRESENCE OF AN UPPER LEVEL
TROUGH TO THE N IS ALSO CONTRIBUTING TO THE LARGE AREA OF
CONVECTION.

...DISCUSSION...

GULF OF MEXICO...
A LARGE SCALE UPPER LEVEL RIDGE COVERS THE GULF OF MEXICO WITH
AXIS FROM THE NW CARIBBEAN TO THE MIDDLE CENTRAL CONUS PROVIDING
DRY SWLY FLOW ALOFT. THE RIDGE SUPPORTS SURFACE RIDGING ACROSS
THE SE CONUS AND THE GULF ANCHORED BY A 1022 MB HIGH S OF
LOUISIANA NEAR 29N91W. LIGHT ANTI-CYCLONIC SURFACE WINDS ARE
AROUND THE RIDGE ALONG WITH MOSTLY CLEAR SKIES BESIDES A FEW
PATCHY FAIR WEATHER CUMULUS CLOUDS. SOME OF THESE CLOUDS MAY BE
PRODUCING ISOLATED SHOWERS N OF THE YUCATAN PENINSULA AND IN THE
WRN BAY OF CAMPECHE. EXPECT FAIR CONDITIONS TO CONTINUE ACROSS
THE BASIN AS HIGH PRESSURE LINGERS OVER THE AREA.

CARIBBEAN SEA...
SHOWERS/THUNDERSTORMS CONTINUE ACROSS THE SW CARIBBEAN POSING A
THREAT FOR FLOODING ACROSS PORTIONS OF CENTRAL AMERICA. A
SURFACE TROUGH IS ANALYZED FROM NEAR 17N76W TO A 1009 MB SURFACE
LOW OFF THE COAST OF PANAMA NEAR 11N78W WITH THE TROUGH
CONTINUING SSW ACROSS COSTA RICA TO NEAR 9N86W. THIS TROUGH IS
EMBEDDED WITHIN A LARGE CYCLONIC GYRE THAT HAS BEEN SITUATED
ACROSS THIS PORTION OF THE BASIN FOR SEVERAL DAYS. SURFACE
CONVERGENCE ALONG WITH DIFFLUENCE ALOFT BETWEEN UPPER RIDGING
COVERING THE WRN AND CENTRAL CARIBBEAN AND CYCLONIC FLOW ALOFT
ACROSS THE ERN PACIFIC ARE PRODUCING SCATTERED
SHOWERS/THUNDERSTORMS FROM N OF PANAMA TO 16N BETWEEN 74W-85W
IMPACTING PORTIONS OF PANAMA...COSTA RICA...AND NICARAGUA. TOTAL
PRECIPITABLE WATER IMAGERY INDICATES AN AREA OF HIGH MOISTURE
LEVELS ACROSS THIS AREA. A FEW ISOLATED SHOWERS/THUNDERSTORMS
EXTEND INTO THE NW CARIBBEAN FROM 16N-21N BETWEEN 80W-85W. THE
REMAINDER OF THE ERN HALF OF THE BASIN IS EXPERIENCING MOSTLY
FAIR WEATHER UNDER THE INFLUENCE OF DRY AIR ALOFT AROUND THE
AFOREMENTIONED UPPER LEVEL RIDGE THAT IS ACROSS THE WRN AND
CENTRAL CARIBBEAN. UPPER LEVEL CYCLONE IS SITTING OVER THE
LESSER ANTILLES...BUT IS CAUSING NO SIGNIFICANT WEATHER. EXPECT
CONTINUED SHOWER ACTIVITY ACROSS THE SW CARIBBEAN AS THE LOW
PRESSURE SYSTEM MOVES NW INCREASING THE PROBABILITY FOR
SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF NRN CENTRAL AMERICA.

ATLANTIC OCEAN...
AN UPPER LEVEL CYCLONE NEAR NOVA SCOTIA WITH TROUGH AXIS
EXTENDING TO THE SW SUPPORTS A COLD FRONT THAT ENTERS THE
DISCUSSION AREA NEAR 32N50W CONTINUING ALONG 26N58W 24N70W
BECOMING STATIONARY TO NE CUBA NEAR 21N75W. SCATTERED
SHOWERS/THUNDERSTORMS ARE WITHIN 90 NM OF THE FRONT BETWEEN CUBA
AND THE BAHAMAS...AND WITHIN 90 NM AHEAD OF THE FRONT BETWEEN
66W-73W. ISOLATED SHOWERS ARE WITHIN 90 NM AHEAD OF THE FRONT
ELSEWHERE. A DRY STABLE AIR MASS IS LEFT IN THE WAKE OF THE
FRONT PROVIDING FAIR CONDITIONS ACROSS THE SW N ATLC. AHEAD OF
THE FRONT...A WEAK 1014 MB HIGH IS NEAR 26N48W SUPPORTED BY AN
UPPER LEVEL RIDGE EXTENDING FROM AN ANTI-CYCLONIC CENTER NEAR
10N50W WITH AXIS TO NEAR 41N41W. FARTHER E...A SURFACE TROUGH
EXTENDS ALONG 32N24W 27N28W 21N45W SUPPORTED BY AN UPPER LEVEL
TROUGH EXTENDING FROM THE AZORES ISLANDS TO W OF THE CAPE VERDE
ISLANDS. POSSIBLE ISOLATED SHOWERS ARE ALONG THE SURFACE TROUGH
AXIS. THE UPPER TROUGH IS HELPING ENHANCE CONVECTION ALONG THE
ITCZ. WEAK SURFACE RIDING IS ACROSS THE FAR E ATLC SUPPORTED BY
A 1018 MB HIGH NEAR 31N19W.

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

$$
WALTON





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