[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201800
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED OCT 20 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
1745 UTC.

...SPECIAL FEATURES...
A BROAD AREA OF LOW PRESSURE WITH ACCOMPANYING SHOWERS AND
THUNDERSTORMS ARE OVER THE W CARIBBEAN SEA ABOUT 60 MILES
SOUTHWEST OF GRAND CAYMAN. AT 20/1800 UTC A PARTIALLY EXPOSED
1007 MB LOW IS CENTERED NEAR 17N82W. SCATTERED HEAVY SHOWERS AND
ISOLATED THUNDERSTORMS ARE ENE OF THE LOW CENTER FROM 16N-22N
BETWEEN 76W-82W INCLUDING THE WESTERN TIP OF JAMAICA. ALTHOUGH
ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY CONDUCIVE FOR
DEVELOPMENT...CONDITIONS ARE EXPECTED TO BECOME SOMEWHAT MORE
FAVORABLE FOR A TROPICAL DEPRESSION TO FORM DURING THE NEXT DAY
OR SO. THERE IS A HIGH CHANCE OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT DRIFTS TO THE SOUTH OR
SOUTHEAST. INTERESTS IN THE NORTHWESTERN CARIBBEAN SEA SHOULD
CONTINUE TO MONITOR THE PROGRESS OF THIS DISTURBANCE. REGARDLESS
OF DEVELOPMENT...HEAVY RAINFALL IS POSSIBLE OVER THE CAYMAN
ISLANDS AND JAMAICA DURING THE NEXT COUPLE OF DAYS.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 7N18W 6N27W 10N36W...RESUMING NEAR
8N42W 6N52W 10N62W. A SURFACE TROUGH IS N OF THE ITCZ EXTENDING
FROM 18N35W THROUGH A 1012 MB LOW NEAR 13N39W TO 10N40W WITH
CLUSTERS OF SCATTERED MODERATE CONVECTION WITHIN 110 NM ON
EITHER SIDE OF THE THROUGH AXIS. CLUSTERS OF SCATTERED WEAK TO
MODERATE CONVECTION ARE FROM 3N-15N E OF 23W INCLUDING THE W
COAST OF AFRICA AND THE PRIME MERIDIAN. CLUSTERS OF SCATTERED
WEAK CONVECTION ARE WITHIN 60 NM ON EITHER SIDE OF THE ITCZ AXIS
BETWEEN 23W AND 31W. SIMILAR CONVECTION IS W OF 56W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD MID-UPPER RIDGE CENTERED INLAND OVER CENTRAL MEXICO IS
DOMINATING MOST OF THE AREA OF DISCUSSION GIVING MOSTLY CLEAR
SKIES AND WITH FEW AREAS OF SCATTER LOW LEVEL STRATOCUMULUS
CLOUDS EMBEDDED IN THE LIGHT ANTICYCLONIC SFC FLOW. A WEAK
SURFACE RIDGE REMAINS OVER THE NW GULF ANCHORED BY A 1018 MB
HIGH NEAR 27N93W. THE ONLY AREA OF ACTIVE WEATHER IS OCCURRING
OVER THE FAR SW COASTAL WATERS OF THE FLORIDA PENINSULA AND THE
FLORIDA STRAITS...E OF 83W S OF 26N...DUE TO DIFFLUENCE ALOFT
COUPLED WITH LOW LEVEL MOISTURE IN THE FAR SE BASIN. STRONG
SUBSIDENCE AND DRY AIR ALOFT COVERS THE REMAINDER OF THE AREA.

CARIBBEAN SEA...
A LOW PRESSURE SYSTEM IS OVER THE WESTERN CARIBBEAN NEAR 17N82W.
SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. ELSEWHERE OUTSIDE
THE CONVECTION ASSOCIATED TO THE SPECIAL FEATURE...DRY AND
STABLE AIR ALOFT COVERS MOST OF THE AREA OF DISCUSSION PROVIDING
RELATIVELY FAIR WEATHER CONDITIONS WITH A FEW AREAS OF SCATTERED
SHOWERS EMBEDDED IN THE TRADE WINDS. WITHIN THIS BROAD REGION OF
DRYNESS...AN ELONGATED N/S UPPER LOW REMAINS OVER THE FAR EAST
BASIN STILL NOT PRODUCING ANY SIGNIFICANT WEATHER.

ATLANTIC OCEAN...
A BROAD MID-UPPER LEVEL TROUGH COVERS THE THE EASTERN CONUS. A
BROAD UPPER RIDGE ANCHORED IS IN THE CENTRAL ATLC BY A 1024 MB
HIGH NEAR 33N53W. THIS WEATHER SCENARIO IS GENERATING AN AREA OF
SURFACE CONVERGENCE FROM 23N-30N BETWEEN 66W-71W. SCATTERED WEAK
TO ISOLATED MODERATE CONVECTION IS OBSERVED IN THIS AREA. A WEAK
UPPER LEVEL TROUGH OVER THE EASTERN ATLC SUPPORTS A COLD FRONT
THAT ENTERS THE DISCUSSION AREA NEAR 32N23W...EXTENDING SW TO
29N28W. FROM THAT POINT...A SURFACE TROUGH CONTINUES TO NEAR
26N39W...BECOMING A SHEAR/REMNANT CLOUD LINE TO NEAR 22N49W.
SCATTERED WEAK CONVECTION IS WITHIN 80 NM EAST OF THE COLD
FRONT. SCATTERED WEAK CONVECTION IS WITHIN 40 NM ON EITHER SIDE
OF THE SURFACE TROUGH. POSSIBLE ISOLATED CONVECTION IS WITHIN 30
NM ON EITHER SIDE OF THE SHEAR LINE. THE REST OF THE AREA OF
DISCUSSION REMAINS UNDER FAIR WEATHER CONDITIONS SUPPORTED BY A
DRY UPPER ATMOSPHERE SEEN ON WATER VAPOR IMAGERY.

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

$$

GARCIA




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