[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180543
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN SEP 18 2011

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF SENEGAL
NEAR 14N17W TO A 1009 MB LOW NEAR 12N23W TO A SECOND 1009 MB LOW
NEAR 12N33W TO A THIRD 1009 MB LOW NEAR 9N40W ENDING NEAR 9N43W
WHERE THE ITCZ CONTINUES TO 8N60W. ISOLATED MODERATE/STRONG
CONVECTION IS WITHIN 120 NM OF THE EASTWARD MOST SURFACE LOW.
SIMILAR ACTIVITY IS FROM 8N-11N BETWEEN 24W-28W. LARGE CLUSTERS
OF STRONG CONVECTION SURROUND THE OTHER TWO LOWS FROM 8N-11N
BETWEEN 34W-44W...AND FROM 12N-13N BETWEEN 34W-35W. ALL THREE
LOWS ARE EXPECTED TO MOVE WWD.

...DISCUSSION...

GULF OF MEXICO...
FAIR WEATHER IS ACROSS THE GULF OF MEXICO TONIGHT WITH
LIGHT ANTI-CYCLONIC SURFACE FLOW AROUND HIGH PRESSURE CENTERED
OVER THE GREAT LAKES AND NEW ENGLAND REGION. ALOFT...UPPER
RIDGING DOMINATES EXTENDING FROM CENTRAL MEXICO TO THE N CENTRAL
GULF COAST. DRY AND SUBSIDENT AIR ACCOMPANIES THE RIDGE WHICH IS
HELPING MAINTAIN THE PLEASANT CONDITIONS. HOWEVER...SOME
MOISTURE FROM THE E PACIFIC IS BEING WRAPPED AROUND THE WRN SIDE
OF THE UPPER RIDGE WHICH HAS MADE ITS WAY TO SRN TEXAS WHERE AN
AREA OF SHOWERS/THUNDERSTORMS HAS POPPED UP. DOPPLER RADAR ALSO
INDICATES SOME ISOLATED SHOWERS IN THE SE GULF OFF THE COAST OF
SW FLORIDA. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS BESIDES
A SLIGHT INCREASE IN THE CHANCE OF RAIN OVER THE SE GULF AS AN
AREA OF MOISTURE TO THE E ADVECTS WWD.

CARIBBEAN SEA...
DEEP LAYER MOISTURE CONTINUES TO IMPACT MUCH OF THE CARIBBEAN
WITH THE FIRST AREA SITTING OVER THE WRN HALF OF THE BASIN W OF
77W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 20N
BETWEEN 80W-86W...WITH A FEW CLUSTERS ALSO NEAR JAMAICA AND
CENTRAL CUBA. A SURFACE TROUGH EXTENDS JUST E OF BELIZE
CONTINUING ACROSS HONDURAS PRODUCING A FEW ISOLATED
SHOWERS/THUNDERSTORMS WITH SOME STRONGER ACTIVITY OVER SRN
GUATEMALA AND EL SALVADOR. STRONG SHOWERS/THUNDERSTORMS ARE ALSO
OVER NRN COLOMBIA AND COSTA RICA INFLUENCED BY THE MONSOON
TROUGH THAT EXTENDS ACROSS COSTA RICA TO NRN COLOMBIA. AN UPPER
LEVEL LOW IS DOMINATING THE ERN CARIBBEAN CENTERED S OF PUERTO
RICO. DRY AIR IS BEING WRAPPED AROUND THE WRN SIDE OF THE UPPER
LOW KEEPING THE CENTRAL CARIBBEAN UNDER MOSTLY FAIR CONDITIONS
EXCEPT FOR A CLUSTER OF SHOWERS/THUNDERSTORMS S OF HAITI.
CLUSTERS HAVE ALSO POPPED UP OVER NRN VENEZUELA AND IN THE ERN
CARIBBEAN FROM 14N-16N BETWEEN 63W-66W NEAR A SURFACE TROUGH
EXTENDING FROM THE VIRGIN ISLANDS TO NRN VENEZUELA NEAR 10N65W.
MOST OF THE REMAINING SHOWER/THUNDERSTORM ACTIVITY ASSOCIATED
WITH THE UPPER LOW IS N AND E OF THE ISLANDS. EXPECT MOIST
CONDITIONS TO REMAIN OVER THE WRN CARIBBEAN AND CENTRAL AMERICA.
MOISTURE IN THE ERN CARIBBEAN IS EXPECTED TO DRIFT WWD WHICH
SHOULD INCREASE THE SHOWER ACTIVITY OVER THAT PORTION OF THE
BASIN.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH OVER THE ERN SEABOARD IS SUPPORTING A
STATIONARY FRONT WHICH JUST CLIPS THE AREA AND EXTENDS TO NE
FLORIDA NEAR 30N81W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN
60 NM SE OF THE FRONT. A SURFACE TROUGH CONTINUES TO SIT OVER
THE CENTRAL BAHAMAS FROM 29N73W TO 20N76W. MOST OF THE SHOWER
ACTIVITY NEAR THE TROUGH HAS DIED OUT WITH ONLY POSSIBLE
ISOLATED SHOWERS BESIDES AN AREA NE OF THE TROUGH NEAR 29N71W.
AN UPPER LEVEL LOW SPINNING S OF PUERTO RICO IS SUPPORTING
CLUSTERS OF SHOWERS/THUNDERSTORMS S OF 27N BETWEEN 56W-70W.
SIMILAR ACTIVITY IS E OF THE LESSER ANTILLES FROM 11N-20N
BETWEEN 55W-61W IN THE AREA OF DIFFLUENCE ALOFT AROUND THE ERN
SIDE OF THE UPPER LOW/TROUGH. FARTHER E...BROAD SURFACE RIDGING
IS COVERING MOST OF THE ERN ATLC ANCHORED BY A 1032 MB HIGH N OF
THE AZORES ISLANDS SUPPORTED BY AN UPPER LEVEL RIDGE NEAR
45N25W. HOWEVER...AN UPPER LEVEL LOW SW OF THE AZORES ISLANDS
NEAR 32N39W IS SUPPORTING A SURFACE LOW PRESSURE SYSTEM N OF THE
DISCUSSION AREA WHICH HAS A SURFACE TROUGH EXTENDING ALONG
32N37W TO 26N45W. ISOLATED SHOWERS ARE WITHIN 400 NM SE OF THE
TROUGH AXIS. UPPER LEVEL RIDGING IS TO EITHER SIDE OF THE UPPER
LOW OVER THE TROPICAL ATLC.

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

$$
WALTON





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